title:
Supersymmetric SU(3) X U(1) Gauge Model: Higgs Structure at the
  Electroweak Scale

abstract:
  We consider a supersymmetric version of the recently proposed SU(3) X U(1)
extended gauge model. We show that it is possible to have only two Higgs
doublets at the SU(2) X U(1) energy scale but they are not those of the minimal
supersymmetric standard model. In particular, the upper bound on the lightest
scalar boson of this model is $4 M_Z \sin \theta_W$ at tree level and goes up
to 189 GeV after radiative corrections.


title:
The Implications of Naturalness in Effective Field Theory on the Masses
  of Resonances

abstract:
  Many years ago Weinberg formulated a definition of ``naturalness'' for
effective theories: if an effective theory is to make sense, coefficients must
not change too much when the cutoff scale is changed by a factor of order 1. As
an example, we consider simple field theories in which an $O(N)$ symmetry
spontaneously breaks to $O(N-1)$. We show that in these theories Weinberg's
criterion for a natural effective theory may be applied directly to the
$S$-matrix; it implies that the scale of new physics, beyond the Goldstone
bosons, may not be too large: there is always a particle or a cut of mass below
or about $4 \pi f / \sqrt{N}$. We discuss the range of convergence of the
expansion of the chiral Lagrangian. It appears to be impossible to construct an
underlying theory of the type considered here that fails to satisfy Weinberg's
criterion.


title:
First Corrections to Hyperfine Splitting and Lamb Shift Induced by
  Diagrams with Two External Photons and Second Order Radiative Insertions in
  the Electron Line

abstract:
  Contributions to HFS and to the Lamb shift intervals of order
$\alpha^2(Z\alpha)^5$ induced by graphs with two radiative photons inserted in
the electron line are considered. It is demonstrated that this last gauge
invariant set of diagrams which are capable of producing corrections of
considered order consists of nineteen topologically different diagrams.
Contributions both to HFS and Lamb shift induced by graphs containing one-loop
electron self-energy as a subgraph and also by the graph containing two
one-loop vertices are obtained.


title: Beyond S, T and U

abstract:
  The contribution to precision electroweak measurements due to TeV physics
which couples primarily to the $W^\pm$ and $Z$ bosons may be parameterized in
terms of the three `oblique correction' parameters, S, T and U. We extend this
parameterization to physics at much lower energies, $\ge 100$ GeV, and show
that in this more general case three more parameters are required (which we
call V, W and X). Only two of these appear in neutral-current experiments,
while the third new parameter enters into the $W^\pm$ width.


title: The Weinberg Angle Without Grand Unification

abstract:
  We assume that strong and electroweak interactions become strong at very high
energies. With this assumption, we compute the low-energy gauge coupling
constants $\alpha_i (m_Z)$ as a function of the cutoff scale, taking the
supersymmetric standard model with $3+2n$ families of quark and lepton
multiplets. We find that only the five family case $(n=1)$ is consistent with
the experimental values of the gauge coupling constants. This suggests the
presence of a pair of families at $\sim 1$~TeV.


title: Non-perturbative unification in the light of LEP results

abstract:
  We consider an alternative to conventional GUTs originally proposed by
Maiani, Parisi and Petronzio, where owing to the existence of extra fermion
generations at some intermediate scale, the gauge couplings become large at
high energies. We first comment on how the non- supersymmetric version of this
scenario is ruled out; we then consider the two-loop evolution of the couplings
in the supersymmetric extension of this scenario, and check whether such a
scenario is feasible in the light of the precies values of couplings now
available from LEP.


title: Higgs Bosons: Intermediate Mass Range at e+e- Colliders

abstract:
  We elaborate on the production of the Standard Model Higgs particle at
high-energy $e^+e^-$ colliders through the reaction $e^+e^- \rightarrow ZH$.
Particular emphasis is put on the intermediate mass range. In addition to the
signal we discuss in detail the background processes. Angular distributions
which are sensitive to the spin and parity of the Higgs particle are analyzed.


title:
Using $b$-Tagging to Detect $t\anti t$~Higgs Production with Higgs$\rta
  b\anti b$

abstract:
  We demonstrate that expected efficiencies and purities for $b$-tagging at
SSC/LHC detectors may allow detection of the Standard Model Higgs in $t\anti t
\hsm$ production, with $\hsm\rta b\anti b$ decay, for $80\lsim\mhsm\lsim
130\gev$, provided $\mt\gsim 130\gev$.


title: Nonequilibrium Quantum Field Kinetics

abstract:
  Using the general framework of nonequilibrium statistical mechanics for
relativistic quantum field systems we derive the basic equations of quantum
field kinetics. The main aim of the approach is calculation of observables
associated with quark-gluon plasma which is out of thermal and chemical
equilibrium. We show that in the regime of high rate of the phase and
statistical mixing the perturbation theory for many-body quantum field system
should have the form which much differs from the standard expansion in powers
of coupling constant. ( Figures can be obtained from the author )


title: Heavy dileptons from nonequilibrium QGP

abstract:
  The rate of emission of heavy dileptons from QGP is found without an
assumption of its complete thermal equilibrium. We base on the real-time
quantum field kinetic approach [1] and use the expansion up to the second order
with respect to strong coupling constant $g$. The final answer is not free from
the collinear singularities and we show that this is the actual issue. As a
result the main contribution to the rate of the heavy dileptons production at
$M/T \sim 10$ comes from the process $q\bar{q}g\rightarrow \gamma^{*}$.
  ( Figures can be obtained from the author )


title: Real photons from nonequilibrium QGP

abstract:
  We calculate the rate of the emission of the photons from the QGP. We base on
the real-time kinetic approach [1] without an explicit assumption about a
complete thermal equilibrium in the emitting system.
  ( Figures can be obtained from the author )


title: Thermal Pions

abstract:
  I discuss the absorption and dispersion of pions in hot matter. A two-loop
calculation in the framework of chiral perturbation theory is presented and its
result is compactly written in terms of the two- and three-particle forward
$\pi \pi$ scattering amplitudes. At modest temperatures, $T \le 100$ MeV, the
change in the pion mass is small and its dispersion law closely resembles the
free space one. At these temperatures, all quantities of interest are given to
a good degree of accuracy by the first term in the virial expansion which is
linear in the density. (BUTP-93/16, uses espcrc1.sty from North-Holland
Publishing)


title: Inverse Neutrinoless Double $\beta$-Decay at the NLC?

abstract:
  The NLC may allow us to search for the `inverse' process to neutrinoless
double-$\beta$ decay, $e^-e^-\to W^-W^-$, which probes the existence of
Majorana masses for neutrinos. Expectations for the observation of this process
in both the Standard Model and its extension, the Left-Right Symmetric Model,
are examined. (Talk given at the {\it {Workshop on Physics and Experiments at
Linear $e^+e^-$ Colliders}}, Waikoloa, Hawaii.)


title: Combining Chiral and Heavy Quark Symmetries

abstract:
  The chiral and heavy quark symmetries of QCD are reviewed. These symmetries
are used to predict some low-momentum properties of hadrons containing a single
heavy quark. (Lectures given at the CCAST Symposium on Particle Physics at the
Fermi Scale May27-June4,1993)


title:
Matter Induced Neutrino Decay: New Candidate for the Solution to the
  Solar Neutrino Problrm

abstract:
  Effects of the dense matter can induce the neutrino decay even if neutrinos
are stable in vacuum. This is due to coherent interactions with matter which
lead to energy level-splitting between the neutrino and antineutrino states and
thereby provide available phase space for the majoron emission. We show that
the matter induced decay can be a plausible candidate for the explanation of
solar neutrino deficit, provided that there exist new flavour-changing weak
range interactions of neutrino with matter constituents, and constant of
$\tau$-neutrino coupling to the majoron is sufficiently large. This mechanism
naturally implies the hierarchy between the ratios Z=(measured signal)/(SSM
expectation) for Ga-Ge, nu_e-e scattering and Cl-Ar experiments -
Z_{GA}>Z_{K}>Z_{Cl}. The important feature of the matter induced decay is the
prediction of solar antineutrino flux with substantially degraded energy
spectrum compared to solar neutrinos. This scenario can be unambiguously tested
by future solar neutrino detectors BOREXINO/BOREX and SNO.


title: Supersymmetry Phenomenology

abstract:
  We review some recent results and future prospects in the phenomenology of
Supersymmmetry. We discuss the searches for superpartner states, the searches
for Higgs bosons in the minimal SUSY model, and additional parameter
constraints arising in SUSY-GUT models.


title: Collider Jets in Perturbation Theory

abstract:
  Recent progress in the perturbative analysis of hadronic jets, especially in
the context of hadron colliders, is discussed. The characteristic feature of
this work is the emergence of a level of precision in the study of the strong
interactions far beyond that previously possible. Inclusive cross sections for
high energy jets at the Tevatron are now perturbatively calculable with a
reliability on the order of 10%. At present this theoretical precision is
comparable to the quoted experimental errors. Progress has also been made
towards understanding both the internal structure of jets and the influence of
the details of the jet-defining algorithm.


title: The Phenomenological Viability of Top Condensation

abstract:
  We discuss how the full dynamics of top condensation models can modify the
relations between the physical top mass, the amount of custodial $SU(2)$
violation and the weak gauge boson masses. It is emphasized that it is possible
to get phenomenologically acceptable relations between $\Delta\rho$, $m_t$ and
$M_W$ and that in addition the scale of new physics can be chosen to be ${\cal
O}(TeV)$ such that a fine--tuning problem is avoided.


title:
Chooz and Perry: New Experiments for Long Baseline Reactor Neutrino
  Oscillations

abstract:
  We discuss the Chooz experiment, a long baseline search for neutrino vacuum
oscillations, which will utilize a large gadolinium-loaded liquid scintillation
detector one km from a large nuclear power station in France. The 300-meter
(water equivalent) underground site of the detector reduces cosmic ray muons,
the main source of background in this type of experiment, by a factor of 300,
thereby allowing clean detection of antineutrinos from the reactor. The
experimental goal is to probe \Delta m^2 values down to 1E-3 eV^2 for large
values of sin^2 2\theta and mixing angles to 0.08 for favorable regions of
\Delta m^2. A subsequent experiment which will have a 13 km baseline at the
former IMB site in Ohio and which can reach \Delta m^2 = 8E-5 eV^2 is also
briefly described.


title: Massive Neutrinos as Probe of Higher Unification

abstract:
  There are strong indications for neutrino masses and mixings in the data on
solar neutrinos as well as in the observed deficit of muon neutrinos from the
atmosphere. The COBE data and other analysis of the large scale structure in
the Universe also seems to require a hot component in the universe's dark
matter, which can be interpreted as a massive neutrino with mass in the few eV
range. Non-zero neutrino mass is a strong indication of a new local $B-L$
symmetry of electro-weak interactions . In particular, it is noted that the
simplest picture based on the left-right symmetric unification with a high
scale for the $B-L$ symmetry (as well as the scale of the right-handed gauge
boson $W_R$) as required by the constraints of grandunification and present LEP
data in a minimal $SO(10)$ model, can accomodate the solar neutrino data and a
weak hot dark matter neutrino but not the atmospheric neutrino puzzle. A model
with low scale $W_R$ ( in the TeV range) where the Dirac mass of the neutrino
arises at the one loop level can also do the same job. The low $W_R$ picture
can be tested in many rare decay experiments.


title: Level-Crossing in the Instanton-Anti-Instanton Valley

abstract:
  We study the level crossing of the fermion system described by the euclidean
Dirac Hamiltonian in the valley background.
  One chiral fermion level is shown to cross twice the zero value in the case
of well-separated instanton-anti-instanton background.
  Below a critical separation, however, level crossings are absent. The
phenomenon can be interpreted as the transition to a gauge field configuration
of purely perturbative nature, below a critical instanton-anti-instanton
separation. In the context of high-energy electroweak interactions, our
findings seem to definitely invalidate some optimistic argument concerning the
observability of baryon number violation based on the use of the optical
theorem in conjunction with the valley fields.


title:
The Coupling of the Pion to Two Gauge Fields and to Leptons in a
  Dynamically Broken Gauge Theory

abstract:
  We show how a spontaneously broken gauge theory of fermions endowed with a
composite scalar multiplet becomes naturally anomaly-free, and yet describes
the correct couplings of the pion to two gauge fields and to leptons: the first
coupling is the same as computed from the chiral anomaly, and the second
identical with that obtained from the `Partially Conserved Axial Current'
hypothesis. For the sake of simplicity, we only study here the abelian case.


title: SUSY Soft Breaking Terms from String Scenarios

abstract:
  The general SUSY soft breaking terms for a large class of phenomenologically
relevant string scenarios (symmetric orbifolds) are given. They show a certain
lack of universality, but not dangerous for flavor changing neutral currents.
To get more quantitative results a specific SUSY breaking mechanism has to be
considered, namely gaugino condensation in the hidden sector. Then, it turns
out that squark and slepton masses tend to be much larger than scalar masses
($m_{\phi} > 10 M_a$), which probably is a quite general fact. Experimental
bounds and the requirement of a successful electroweak breaking without fine
tuning impose further restrictions on the soft breaking terms. As a consequence
the gluino and chargino masses should be quite close to their present
experimental limits, whereas squark and slepton masses should be much higher (>
1 TeV).


title: Direct vs. resolved photon: an exercise in factorization

abstract:
  Direct and resolved photon interactions are shown to be intimately related
through the factorization mechanism. It is argued that in theoretically
consistent analysis of jet production in $\gamma$p and ep collisions the LO
resolved $\gamma$ contribution must be considered together with the NLO direct
$\gamma$ component. Recent data from HERA therefore do not provide a direct
evidence for the former component, but should rather be interpreted as a
manifestation of the $O(\alpha\alpha_s^2)$ term in $\gamma$p and, via the
Weizs\"acker-Williams approximation, in ep interactions.


title: The Nucleon Spin Crisis Bible

abstract:
  When the new data on polarised lepton nucleon scattering are compared at the
same value of $Q^2$ and with a common set of assumptions, a consistent picture
of the spin content of the nucleon begins to emerge. Higher order effects in
$0(\alpha_s)$, higher twist effects, modern data on unpolarised structure
functions and an updated value for F/D are all important in analysing the data.
The detailed x dependences of the polarisation asymmetry in the valence quark
region are shown to confirm 20 year old predictions of the quark model and I
argue that these are an important ingredient in decoding the nucleon spin
puzzle.


title: Consistent Analysis of the Spin Content of the Nucleon

abstract:
  The recent measurements of lepton nucleon scattering with polarised neutron
and deuteron targets are analysed together with the previous polarised proton
data in a mutually consistent way. The detailed $x$-dependence of the
polarisation asymmetry in the valence region is shown to be in agreement with
historical predictions based on quark models. The Bjorken sum rule is shown to
be confirmed at the $1\sigma$ level and estimates of the spin content of the
nucleon $\Delta q$ are extracted. While the average value of $\Delta q$ from
the three experiments comes out to be $0.41\pm0.05$ (to be compared with the
naive quark model theoretical expectation of 0.58) this experimental average
value is more than one standard deviation from the value obtained from any
individual experiment.This inconsistency can be overcome by allowing arbitrary
higher twist contributions but the resulting precision is poor, $\Delta q =
0.38\pm 0.48$.


title: No Parity Violation without R Parity Violation

abstract:
  In a class of supersymmetric left-right models (SUSYLR) of weak interactions
where R-parity is automatically conserved, we show that spontaneous breakdown
of parity CANNOT occur without spontaneous breakdown of R-parity. This
intriguing result connects two physically different scales in supersymmetric
models.


title: Electroweak corrections to decays involving a charged Higgs boson

abstract:
  We present complete one-loop radiative corrections to the decay rate of a top
quark into a charged Higgs boson and a bottom quark, and for the decay of a
charged Higgs boson into leptons. The results are discussed in the framework of
the two Higgs boson extension of the Standard Model suggested by supersymmetry.
The effect of electroweak corrections after exclusion of universal corrections
$\Delta r$ is found to decrease the partial width of the top quark typically by
5%.


title:
Implications of $b\rightarrow s\gamma$ for CP Violation in Charged
  Scalar Exchange

abstract:
  In models of three or more scalar doublets, new CP violating phases appear in
charged scalar exchange. These phases affect CP asymmetries in neutral $B$
decays, even if Natural Flavor Conservation holds. The recent upper bound on
the decay $b\rightarrow s\gamma$ constrains the effect to be at most of order a
few percent. Modifications of constraints on the CKM parameters open an
interesting new region in the $\sin2\alpha-\sin2\beta$ plane even in the
absence of new phases.


title: Dilution of Cosmological Densities by Saxino Decay

abstract:
  Saxino decay can generate significant cosmological entropy, and hence dilute
theoretical estimates of the present mass density of a given particle species.
The dilution factor depends on the saxino and axion masses, and is constrained
by the requirement that saxino decay should not affect nucleosynthesis, as well
as by the usual requirement that the axion density be less than the critical
density. The latter constraint is evaluated carefully, under both the
Harari-Sikivie and Davis proposals about the emission spectrum from axionic
strings. Uncertainties are carefully evaluated, points of principle are
addressed, and with an eye to future numerical simulation the spacing and
typical oscillation wavelength of the strings are represented by parameters
varying in the range 1 to 3. Within the constraints, the entropy dilution
varies from 1 to $10^{-4}$. Only saxinos originating from thermal equilibrium
are considered, so that more dilution might arise from non-thermal saxinos.


title: Soft Collective Excitations in Hot Gauge Theories

abstract:
  THE PREVIOUS LATEX STRUCTURE WAS MODIFIED IN ORDER TO ALLOW FOR A DIRECT
IMPRESSION OF THE PAPER, WITHOUT SUPPLEMENTARY SPLITTING. THERE IS NO TEXT
MODIFICATION.


title: Construction of a New Electroweak Sphaleron

abstract:
  We present a self-consistent ansatz for a new sphaleron in the electroweak
standard model. The resulting field equations are solved numerically. This
sphaleron sets the height of the energy barrier for the global SU(2) anomaly.


title:
On Non-Perturbative Effects at the High-Temperature Electroweak Phase
  Transition

abstract:
  It is argued that confining effects in 3-dimensional non-Abelian gauge
theories (high-temperature limit of 4-dimensional ones) imply the existence of
the condensates of the gauge and Higgs fields in 3-d vacuum. This
non-perturbative effect can decrease the energy of the phase with unbroken
symmetry and may result in the creation of a barrier separating the broken and
unbroken phases. Thus the high-temperature phase transitions in gauge theories
can be stronger first order than is expected from perturbation theory. The
applications of these results to electroweak baryogenesis are briefly
discussed.


title: Predicting the neutrino spectrum in minimal SO(10) Grand Unification

abstract:
  Analysis of the model of Babu and Mohapatra for the mass matrices in SO(10),
with survey of the different types of neutrino spectra possible in that model


title: Gluon Plasma Frequency -- the Next-to-Leading Order Term

abstract:
  The longitudinal-electric oscillations of the hot gluon system are studied
beyond the well known leading order term at high temperature $T$ and small
coupling $g$. The coefficient $\eta$ in $\omega^2 = m^2 \, (1+ \eta \, g \wu N
\, )$ is calculated, where \hbox{$\omega \equiv \omega (\vc q =0)$} is the
long-wavelength limit of the frequency spectrum, $N$ the number of colours and
$m^2=g^2 N T^2/9$. In the course of this, for the real part of the gluon
self-energy, the Braaten-Pisarski resummation programme is found to work well
in all details. The coefficient $\eta$ is explicitly seen to be gauge
independent within the class of covariant gauges. Infrared singularities cancel
as well as collinear singularities in the two-loop diagrams with both inner
momenta hard. However, as it turns out, none of these two-loop contributions
reaches the relative order $O(g)$ under study. The minus sign in our numerical
result $\; \eta = -.18 \; $ is in accord with the intuitive picture that the
studied mode might soften with increasing coupling (lower temperature) until a
phase transition is reached at zero-frequency. The minus sign thus exhibits the
'glue' effect for the first time in a dynamical quantity of hot QCD.


title:
Origin of Difference between $\overline{d}$ and $\overline{u}$ Partons
  in the Nucleon

abstract:
  Using the Euclidean path-integral formulation for the hadronic tensor, we
show that the violation of the Gottfried sum rule does not come from the
disconnected quark-loop insertion. Rather, it comes from the connected (quark
line) insertion involving quarks propagating in the backward time direction. We
demonstrate this by studying sum rules in terms of the scalar and axial- vector
matrix elements in lattice gauge calculations. The effects of eliminating
backward time propagation are presented.


title: Electroweak symmetry breaking through supersymmetry breaking

abstract:
  The connection between the scales of $ {\rm SU} (2)\times {\rm U} (1) $ gauge
symmetry breaking and supersymmetry breaking is didactically displayed in the
framework of a T.O.Y. (Theory Overestimating Yukawas) model, a version of the $
(M+1)SSM $ (supersymmetric extension of the standard model with a gauge
singlet) in which the relevant parameters are determined in the fixed point
regime. Some conspicuous features of supersymmetric particle physics are
reviewed in the light of this simplified model. An alternative theory
corresponding to lim $ (M+1)SSM \longrightarrow MSSM, $ leads to interesting
inequalities among the supersymmetric breaking parameters of the $ MSSM. $


title: On semi-classical pion production in heavy ion collisions

abstract:
  In high energy heavy ion collisions the pion multiplicity is large, and one
might expect that pions are radiated semi-classically. The axial symmetry of
the collision and approximately zero isotopic spin of the colliding nuclei
result then in peculiar isotopic spin -- azimuth correlations of the produced
pions. These correlations are easy to test -- and should be tested.


title: Hadronic $W$ production and the Gottfried Sum Rule

abstract:
  The difference in production rate between $W^+$ and $W^-$ at hadron colliders
is very sensitive to the the difference between up- and down-quark
distributions in the proton. This sensitivity allows for a variety of useful
measurements. We consider the difference $d_s(x,Q^2) - u_s(x,Q^2)$ in the sea
distributions and the difference $\Delta u(x,Q^2) - \Delta d(x,Q^2)$ in the
polarized parton distribution functions. In both cases we construct an
asymmetry to reduce systematic uncertainties. Although we discuss measurements
at the Tevatron and future hadron colliders, we find that the Brookhaven
Relativistic Heavy Ion Collider (RHIC) is the most appropriate hadron collider
for these measurements.


title: Valley Singularities and Baryon Number Violation

abstract:
  We consider the valley--method computation of the inclusive cross section of
baryon number violating processes in the Standard Model. We show that any
physically correct model of the valley action should present a singularity in
the saddle point valley parameters as functions of the energy of the process.
This singularity prevents the saddle point configuration from collapsing into
the perturbative vacuum.


title: A Partial Unification Model in Non-commutative Geometry

abstract:
  We consider the construction of $SU(2)_{L}\otimes SU(2)_{R}\otimes SU(4)$
partial unification models as an example of phenomenologically acceptable
unification models in the absence of supersymmetry in non-commutative geometry.
We exploit the Chamseddine, Felder and Fr\"ohlich generalization of the Connes
and Lott model building prescription. By introducing a bi-module structure and
appropriate permutation symmetries we construct a model with triplet Higgs
fields in the $SU(2)$ sectors and spontaneous breaking of $SU(4)$.


title: The Nambu-Jona-Lasinio Chiral Soliton with Constrained Baryon Number

abstract:
  A regularization for the baryon number consistent with the energy in the
Nambu-Jona-Lasinio model is introduced. The soliton solution is constructed
with the regularized baryon number constrained to unity. It is furthermore
demonstrated that this constraint prevents the soliton from collapsing when
scalar fields are allowed to be space dependent. In this scheme the scalar
fields actually vanish at the origin reflecting a partial restoration of chiral
symmetry. Also the influence of this constraint on some static properties of
baryons is discussed.


title: Quartic Anomalous Couplings in $e\gamma$ Colliders

abstract:
  We study the production of gauge boson pairs at the next generation of linear
$e^+e^-$ colliders operating in the $e\gamma$ mode. The processes $e\gamma
\rightarrow VV^\prime F$ ($V,V^\prime =W$, $Z$, or $\gamma$ and $F=e$ or $\nu$)
can give valuable information on possible deviations of the quartic vector
boson couplings from the Standard Model predictions. We establish the range of
the new couplings that can be explored in these colliders based on a $3\sigma$
effect in the total cross section. We also present several kinematical
distributions of the final state particles that could manifest the underlying
new dynamics. Our results show that an $e\gamma$ collider can extend
considerably the bounds on anomalous interactions coming from oblique radiative
corrections and from direct searches in $e^+e^-$ colliders.


title: Quantum Corrections to the Electroweak Sphaleron Transition

abstract:
  We have performed a new exact evaluation of the fluctuation determinant
$\kappa$ of the electroweak sphaleron with $\Theta _W =0$. The results differ
significantly from a previous calculation of this quantity by Carson et. al. .
We find that $\kappa$ is of order 1 in units $(gv)^6$ while the previous
results indicated a strong suppression of the sphaleron transition by this
factor.


title: Standard Model Higgs Boson at Linear Photon Colliders

abstract:
  We will summarize some aspects of the standard model Higgs boson at high
energy $\gamma\gamma$ colliders, where the photon beams are realized by the
laser backscattering method, including the direct Higgs boson production via
$\gamma\gamma\rightarrow H$, and the measurement of the Yukawa coupling via the
channel $\gamma\gamma\rightarrow t\bar tH$.


title: The Top Quark Mass in Supersymmetric SO(10) Unification

abstract:
  The successful prediction of $\sin^2\theta_W$ suggests that the effective
theory beneath the GUT scale is the two-Higgs MSSM. If we further assume that
the unified gauge group contains SO(10), that the two light Higgs doublets lie
mostly in a single irreducible SO(10) representation, and that the $t$, $b$ and
$\tau$ masses originate in renormalizable Yukawa interactions of the form $16_3
O 16_3$, then also the top quark mass can be predicted in terms of the MSSM
parameters. To compute $m_t$ we present a precise analytic approximation to the
solution of the 2-loop renormalization group equations, and study
supersymmetric and GUT threshold corrections and the input value of the $b$
quark mass. The large ratio of top to bottom quark masses derives from a large
ratio, $\tan\beta$, of Higgs vacuum expectation values. We point out that when
$\tan\beta$ is large, so are certain corrections to the $b$ quark mass
prediction, unless a particular hierarchy exists in the parameters of the
model. With such a hierarchy, which may result from approximate symmetries, the
top mass prediction depends only weakly on the spectrum. Our results may be
applied to any supersymmetric SO(10)-like model as long as $\lambda_t\simeq
\lambda_b\simeq\lambda_\tau$ at the GUT scale and there are no intermediate
mass scales in the desert.


title: $\bar B\to\bar K\e^+\e^-$ in Chiral Perturbation Theory

abstract:
  The combined use of chiral $SU(3)$ and heavy quark symmetries allows one to
relate the hadronic form factors for the decay $\bar B\to \bar K\e^+\e^-$ to
those for $\bar B\to\pi\e^-\bar\nu$. We investigate departures from the
symmetry limit which arise from chiral symmetry breaking. The analysis uses
chiral perturbation theory and the heavy quark limit to compute the relevant
hadronic matrix elements. We estimate the size of $SU(3)$ corrections by
computing, at one loop order, the leading nonanalytic dependence on the light
quark masses. The calculation is trustworthy only in the portion of the Dalitz
plot in which the momentum of the kaon or pion is small. We find the
corrections to be~$\sim40\%$.


title:
Renormalization Group Study of the Minimal Supersymmetric Standard Model
  : No Scale Models

abstract:
  We present partial numerical results in the Minimal Supersymmetric Standard
Model with soft breaking of supersymmetry, and radiative breaking of the
electroweak symmetry. We impose the additional relation, bottom mass = tau mass
at the GUT scale. For the special case of the strict no-scale model, in which
global supersymmetry breaking arises solely from soft gaugino masses, we find
that the top mass is expected to be lighter than about 128 GeV. A higher upper
bound for the top mass of about 138 GeV is predicted, if the mass of the bottom
is at the lower end of its experimental uncertainty.


title: Extraction of $Z'$ Coupling Data From $Z' \to jj$ at the LHC and SSC

abstract:
  A recent analysis has shown that it may be possible at the SSC to extract
information about $Z'$ couplings via the decay $Z' \to jj$. This technique was
found to be useful for some extended electroweak models provided the $Z'$ is
relatively light. In the present paper, we generalize this procedure to the LHC
and to $Z'$'s which are more massive than 1 TeV. (Contributed to the {\it
Proceedings of the Workshop on Physics at Current Accelerators and the
Supercollider}, Argonne National Laboratory, June 2-5, 1993.)


title: Quark-gluon vertex and structure of mesons and diquarks

abstract:
  *REVISED VERSION* Two quark propagators with different analytic structure are
employed in on and off mass-shell Bethe-Salpeter type equations for the pion
and scalar diquark form-factors. One of the quark propagators has been
calculated with the inclusion of a trivial quark-gluon vertex and, as a
consequence, contains a complex conjugate pair of logarithmic branch points.
The other quark propagator includes a non-trivial vertex ansatz and is entire,
with an essential singularity at infinity. The different quark propagators lead
to qualitatively different diquark form-factors.


title: Sparticle Spectrum Constraints

abstract:
  The supersymmetric standard model with supergravity-inspired soft breaking
terms predicts a rich pectrum of sparticles to be discovered at the SSC, LHC
and NLC. Because there are more supersymmetric particles than unknown
parameters, one can write down sum rules relating their masses. We discuss the
pectrum of sparticles from this point of view. Some of the sum rules do not
depend on the input parameters and can be used to test the consistency of the
model, while others are useful in determining the input parameters of the
theory. If supersymmetry is discovered but the sum rules turn out to be
violated, it will be evidence of new physics beyond the minimal supersymmetric
standard model with universal soft supersymmetry-breaking terms.


title: Theoretical Predictions for W-Pair Production

abstract:
  We review the status of theoretical predictions for W-pair production at high
energies. We discuss a systematic scenario towards a Monte-Carlo generator for
e^+e^- --> 4f(\gamma), which meets the experimental requirements. In particular
we summarize the recent developments in this field.


title:
Supergravity Grand Unification, Proton Decay and Cosmological
  Constraints

abstract:
  Properties and experimental predictions of a broad class of supergravity
grand unified models possessing an $SU(5)$-type proton decay and $R$ parity are
described. Models of this type can be described in terms of four parameters at
the Gut scale in addition to those of the Standard Model i.e. $m_o$ (universal
scalar mass), $m_{1/2}$ (universal gaugino mass), $A_o$ (cubic soft breaking
parameter) and $\tan\beta=<H_2>/<H_1>$. Thus the 32 SUSY masses can be
expressed in terms of $m_o, m_{1/2}, A_o \tan\beta$ and the as yet unknown
t-quark mass $m_t$. Gut thresholds are examined and a simple model leads to
grand unification consistent with $p$-decay data when $0.114<\alpha_3
(M_z)<0.135$, in agreement with current values of $\alpha_3 (M_Z)$.Proton decay
is examined for the superheavy Higgs triplet mass $M_{H_3}<10M_G(M_G\simeq 1.5
\times10^{16}$~GeV) and squarks and gluinos lighter than 1 TeV. Throughout most
of the parameter space chargino-neutralino scaling relations are predicted to
hold: $2m_{\tilde{Z}_1}\cong m_{\tilde{W}_1}\cong m_{\tilde{Z}_2},
m_{\tilde{W}_1}\simeq(1/4)m_{\tilde{g}}$ (for $\mu>0$) or $m_{\tilde{W}_1}
\simeq(1/3)m_{\tilde{g}}$ (for $\mu<0$), while $m_{\tilde{W}_2}\cong
m_{\tilde{Z}_3}\cong m_{\tilde{Z}_4}>>m_{\tilde{Z}_1}$. Future proton decay
experiments combined with LEP2 lead to further predictions, e.g. for the entire
parameter space either proton decay should be seen at these or the$\tilde{W}_1$
seen at LEP2. Relic density constraints on the $\tilde{Z}_1$ further constrain
the parameter space e.g. so that $m_t<165$~GeV, $m_h<105$~GeV, $m_{\tilde{W}_1}
<100$~GeV and $m_{\tilde{Z}_1}<50$~GeV when $M_{H_3}/M_G < 6$. (Invited talk at
Les Rencontres de Physique de la Vallee D'Aoste}


title: Low-mass dileptons from nonequilibrium QGP

abstract:
  The rate of the emission of the high energy low-mass dileptons from the QGP
is found in the first nonvanishing order with respect to strong coupling. We
base on the real-time kinetic approach [2] without an explicit assumption about
a complete thermal equilibrium in the emitting system. For the class of the
partons distributions which may simulate that of the "hot glue scenario"[1] the
rate of emission is found analytically .
  ( Figures can be obtained from the author )


title:
Natural CP Violation Criteria for the Minimal Supersymmetric Standard
  Model

abstract:
  $CP$ violating effects in the Minimal Supersymmetric Standard Model (MSSM)
can lead to excessively large contributions to the neutron EDM (\dn). We write
criteria which ensure that the low energy supergravity (SUGRA) parametrization
of the MSSM does not require fine-tunings or large mass scales to evade the
constraint from \dn, and consider the implications on SUGRA theories. In
particular, we show that in the Polonyi model, two of the mass scales are in
general complex, meaning that model does not naturally avoid a large \dn\ as is
sometimes claimed.


title:
Guaranteed Detection of a Minimal Supersymmetric Model Higgs Boson at
  Hadron Supercolliders

abstract:
  We demonstrate that expected efficiencies and purities for $b$-tagging at
SSC/LHC detectors should allow detection of at least one of the Higgs bosons of
the Minimal Supersymmetric Model in $t\anti t$~Higgs production, with
Higgs$\rta b\anti b$ decay, over a substantial range of supersymmetric
parameter space. In particular, with the addition of this mode to those
previously considered, there is no region of supersymmetric parameter space for
which {\it none} of the Higgs bosons of the model can be seen at the SSC/LHC.


title: Heavy Quark Symmetry

abstract:
  We review the current status of heavy quark symmetry and its applications to
weak decays of hadrons containing a single heavy quark. After an introduction
to the underlying physical ideas, we discuss in detail the formalism of the
heavy quark effective theory, including a comprehensive treatment of symmetry
breaking corrections. We then illustrate some nonperturbative approaches, which
aim at a dynamical, QCD-based calculation of the universal form factors of the
effective theory. The main focus is on results obtained using QCD sum rules.
Finally, we perform an essentially model-independent analysis of semileptonic
$B$ meson decays in the context of the heavy quark effective theory.


title: Effective Lagrangians with Higher Order Derivatives

abstract:
  The problems that are connected with Lagrangians which depend on higher order
derivatives (namely additional degrees of freedom, unbound energy from below,
etc.) are absent if effective Lagrangians are considered because the equations
of motion may be used to eliminate all higher order time derivatives from the
effective interaction term. The application of the equations of motion can be
realized by performing field transformations that involve derivatives of the
fields. Using the Hamiltonian formalism for higher order Lagrangians
(Ostrogradsky formalism), Lagrangians that are related by such transformations
are shown to be physically equivalent (at the classical and at the quantum
level). The equivalence of Hamiltonian and Lagrangian path integral
quantization (Matthews's theorem) is proven for effective higher order
Lagrangians. Effective interactions of massive vector fields involving higher
order derivatives are examined within gauge noninvariant models as well as
within (linearly or nonlinearly realized) spontaneously broken gauge theories.
The Stueckelberg formalism, which relates gauge noninvariant to gauge invariant
Lagrangians, becomes reformulated within the Ostrogradsky formalism.


title: SUSY-Induced CP Violation in $t$ Decays at $e^-e^+$ Colliders

abstract:
  CP violation in the decays $t \to \ell^+\nu b$ and $\bar t \to \ell^-\bar\nu
\bar b$ from the production process $e^-e^+ \to \ttbar$ is discussed. Since the
asymmetry proposed as a measure of CP violation vanishes even at the one-loop
level in the Standard Model (SM), it may be a useful tool to search for sources
of CP violation outside of the SM. As an illustration the asymmetry has been
computed within supersymmetric extensions of the SM. Prospects for its
measurement at future high-energy linear colliders are discussed.


title: Low--Energy Behavior of Two--Point Functions of Quark Currents

abstract:
  We discuss vector, axial-vector, scalar and pseudoscalar two-point functions
at low and intermediate energies. We first review what is known from chiral
perturbation theory, as well as from a heat kernel expansion within the context
of the extended Nambu-Jona-Lasinio (ENJL) model of ref. \cite{12}. In this work
we derive then these two-point functions to all orders in the momenta and to
leading order in $1/N_c$. We find an improved high-energy behaviour and a
general way of parametrizing them that shows relations between some of the
two-point functions, which are also valid in the presence of gluonic
interactions. The similarity between the shape of the experimentally known
spectral functions and the ones we derive, is greatly improved with respect to
those predicted by the usual constituent quark like models. We also obtain the
scalar mass $M_S = 2 M_Q$ independent of the regularization scheme. In the end,
we calculate fully an example of a nonleptonic matrix element in the
ENJL--model, the $\pi^+-\pi^0$ electromagnetic mass difference and find good
agreement with the measured value.


title:
The Analytical Contribution of Some Eighth-Order Graphs Containing
  Vacuum Polarization Insertions to the Muon (G-2) in QED

abstract:
  The contributions to the $g-2$ of the muon from some eighth-order (four-loop)
graphs containing one-loop and two-loop vacuum polarization insertions have
been evaluated analytically in QED perturbation theory, expanding the results
in the ratio of the electron to muon mass ${(m_e / m_\mu)}$. The results agree
with the numerical evaluations and the asymptotic analytical results already
existing in the literature.


title: Neutralino Annihilation to Gluons

abstract:
  We present a complete calculation of the cross section for neutralino
annihilation into the two-gluon final state. This channel can be quite
important for the phenomenology of neutralino annihilation due to the
well-known helicity suppression of neutralino annihilation into light quarks
and leptons. In addition, we calculate the cross section for annihilation of
neutralinos into a gluon and quark-antiquark pair, and discuss QCD corrections
to the tree-level cross sections for neutralino annihilation into quarks. If
the neutralino is lighter than the top quark, the effect of these results on
high-energy neutrino signals from neutralino annihilation in the Sun and in the
Earth can be significant, especially if the neutralino is primarily gaugino. On
the other hand, our results should have little effect on calculations of the
cosmological abundance of neutralinos. We also briefly discuss implications for
cosmic-ray antiprotons from neutralino annihilation in the galactic halo.


title: Cosmological Bound on the Decay $\pi^0\rightarrow\gamma X$

abstract:
  Using the upper bound on the effective number of light neutrino species
during primordial nucleosynthesis and the cosmological pion-pole mechanism
$\gamma\gamma\rightarrow \pi^0\rightarrow \gamma X$, we obtain an upper limit
on the branching ratio for the decay BR$(\pi^0\rightarrow \gamma X)<3\times
10^{-13}$, where $X$ is any long-lived weakly interacting neutral vector
particle with mass smaller than the neutral pion mass.


title: SU(5)xU(1): a string paradigm of a TOE and its experimental consequences

abstract:
  We present a string-inspired/derived supergravity model based on the flipped
$SU(5)\times U(1)$ structure supplemented by a minimal set of additional matter
representations such that unification occurs at the string scale
($\sim10^{18}\GeV$). This model is complemented by two string supersymmetry
breaking scenaria: the $SU(N,1)$ no-scale supergravity model and a
dilaton-induced supersymmetry breaking scenario. Both imply universal soft
supersymmetry breaking parameters: $m_0=0, A=0$ and
$m_0=\coeff{1}{\sqrt{3}}m_{1/2}, A=-m_{1/2}$ respectively. In either case the
models depend on only three parameters: $m_t$, $\tan\beta$, and $m_{\tilde g}$.
We present a comparative study of the sparticle and Higgs spectra of both
models and conclude that even though both can be partially probed at the
Tevatron, LEPII, and HERA, a larger fraction of the parameter space of the
no-scale model is actually accessible. In both cases there is a more
constrained version which allows to determine $\tan\beta$ in terms of
$m_t,m_{\tilde g}$. In the strict no-scale case we find that the value of $m_t$
determines the sign of $\mu$ ($\mu>0:\,m_t\lsim135\GeV$,
$\mu<0:\,m_t\gsim140\GeV$) and whether the lightest Higgs boson mass is above
or below $100\GeV$. In the more constrained version of the dilaton scenario,
$\tan\beta\approx1.4-1.6$ and $m_t\lsim155\GeV$, $61\GeV\lsim m_h\lsim91\GeV$
follow. Thus, continuing Tevatron top-quark searches and LEPI,II Higgs searches
could probe this restricted scenario completely.


title: Some Questions of Flavor in Supersymmetry

abstract:
  We consider certain naturalness questions in supersymmetric theories. Various
suggestions which give rise to squark degeneracies are reviewed. A stringy
scenario, discussed by Kaplunovsky and Louis, is the only one which leads to
complete degeneracy of squarks and sleptons at the high scale. Alternatives
include the possible existence of a gauged non-Abelian horizontal symmetry,
broken at some scale, and theories in which the ``messengers" of supersymmetry
breaking are gauge interactions. A model of the latter type is described, in
which supersymmetry is {\it dynamically} broken at TeV energies. Models of this
type can solve many of the naturalness problems of supersymmetric theories, and
predict a rich phenomenology at SSC energies.


title: Strong $W_L W_L$ Scattering at Hadronic Supercolliders

abstract:
  We will summarize some aspects of the scenario of a strongly interacting
symmetry breaking sector via which the longitudinal vector boson scattering
becomes strong. We will examine the feasibility of observing such strong $W_L
W_L$ signal at the future hadronic supercolliders.


title:
Enhancing the Higgs signal in $pp\rightarrow ZZ\rightarrow
  \ell^+\ell^-\nu\bar{\nu}$

abstract:
  One of the possible modes suggested for detecting the Higgs particle is
$pp\rightarrow ZZ\rightarrow\ell^+\ell^-\nu\bar{\nu}$, where the Higgs appears
as a resonance on a Jacobian background. Unfortunately there are QCD background
processes which mimic the final state and we are obliged to impose stringent
kinematic cuts to remove them. However, in doing so we also remove a
significant fraction of the signal. In this report we suggest a method, based
on examining the distribution of the final state charged leptons, which could
allow us to relax our cuts and thus salvage the signal.


title: On Quark Confinement

abstract:
  A sufficient condition for the confinement of quarks is presented. Quarks are
shown to be unobservable. Colour singlets are however, observables. The results
of deep inelastic scattering are discussed. We argue that QCD does not exhibit
a deconfining transition.


title: Supersymmetric Unification without Proton Decay

abstract:
  We present a supersymmetric grand unification scheme based on the gauge group
SU(3)_c X SU(3)_L X SU(3)_R in which the proton and the lightest supersymmetric
particle are stable, neutrinos are necessarily massive, and the observed baryon
asymmetry originates in the lepton sector. Such models are also consistent with
the measured value of sin^2\Theta_W as well as unification of the gauge
couplings.


title: Renormalization Group Equations for Seesaw Neutrino Masses

abstract:
  RGEs for coefficients of dim-5 operators giving rise to neutrino masses in
the seesaw mechanism are written down in the SM, 2HDM and MSSM, and solved
numerically. RG evolution of these coefficients modifies tree-level seesaw
predictions for neutrino masses and mixing angles in SO(10)-type GUT models as
strongly as quark Yukawa coupling evolution.


title:
Analysis of Weak-Interaction Effects in High Energy Hadron-Hadron
  Collisions

abstract:
  Parity-violating (pv) effects in inclusive hadron and jet productions in high
energy hadron-hadron collisions are analyzed. Such effects arise from the
interference between strong and weak amplitudes. This interference gives rise
to a nonzero value of the pv parameters $A_L$ and $P_L$, where $A_L$ measures
the difference in the inclusive cross sections of, for example, $p+p\ri {\rm
jet}+X$ ($X$=anything), with one of incident proton beams in a state of $\pm$
helicity, and $P_L$ denotes the longitudinal polarization of a high-energy
baryon (e.g., $\Lambda$) produced in $p+p\ri\Lambda+X$ with the initial proton
beams unpolarized. In the present paper, the single helicity asymmetry $A_L$ in
one-jet, two-jet and two-jet plus photon productions as well as in the
Drell-Yan process $p+p\ri\ell^+\ell^-+{\rm jet}+X$ is probed, and the
longitudinal polarization $P_L$ of the $\Lambda$ produced in unpolarized $pp$
collisions is studied. We conclude that the pv effects in high energy
proton-proton collisions are in general only sensitive to the spin dependent
valence quark distributions.


title:
Deducing L_{fermion} at M_{GUT} using Low Energy Data or Towards a
  Theory of Fermion Masses

abstract:
  In the last 20 years we have accumulated an enormous amount of data on
elementary particles and their interactions. This data serves two purposes: to
fix the phenomenological parameters of the Standard Model [SM] and to verify
that the SM is an excellent description of nature. It is our goal to understand
the origin of these many arbitrary parameters. In this talk we consider a
supersymmetric [SUSY] SO(10) grand unified theory [GUT]. We present a
straightforward procedure, incorporating a general operator analysis, which
allows us to use low energy data to determine the fermionic sector of the
theory at the GUT scale.


title:
Baryogenesis through Collapsing String Loops in Gauged Baryon and Lepton
  Models

abstract:
  A scenario for the generation of the baryon asymmetry in the early Universe
is proposed in which cosmic string loops, predicted by theories where the
baryon and/or lepton numbers are gauged symmetries, collapse during the
friction dominated period of string evolution. This provides a mechanism for
the departure from thermal equilibrium necessary to have a nonvanishing baryon
asymmetry. Examples of models are given where this idea can be implemented. In
particular, the model with the gauge symmetry $SU(3)_{c}\otimes
SU(2)_{L}\otimes U(1)_{Y}\otimes U(1)_{B} \otimes U(1)_{L}$ has the interesting
feature where sphaleron processes do not violate the baryon and lepton numbers
so that no wash out of any initial baryon asymmetry occurs at the electroweak
scale.


title: Heavy Quark Correlations in Photon-Hadron Collisions

abstract:
  We describe a next-to-leading-order calculation of the fully exclusive parton
cross section for the photoproduction of heavy quarks. We use our result to
compute quantities of interest for current fixed-target experiments. We discuss
heavy-quark total cross sections, distributions and correlations.


title:
The Renormalization-Group Improved Higgs Sector of the Minimal
  Supersymmetric Model

abstract:
  In the minimal supersymmetric model (MSSM) all Higgs self-coupling parameters
are related to gauge couplings at tree-level. Leading-logarithmic radiative
corrections to these quantities can be summed using renormalization group
techniques. By this procedure we obtain complete leading-log radiative
corrections to the Higgs masses, the CP-even Higgs mixing angle, and trilinear
Higgs couplings. Additional corrections due to squark mixing can be explicitly
incorporated into this formalism. These results incorporate nearly all
potentially large corrections. Mass shifts to the neutral CP-even Higgs bosons
grow with the fourth power of the top-quark mass and can be significant. The
phenomenological consequences of these results are examined.


title: Toponium as Nonabelian Positronium ?

abstract:
  The expected large mass $m_t$ of the top quark provides for the first time a
chance to discuss the bound-states of the corresponding quantum system as the
nonabelian generalization of positronium, using the full power of relativistic
quantum field theoretic methods which are available for weakly bound systems.
Thus our approach differs in principle from the one used in the vast
phenomenological literature on quarkonium potentials. We emphasize especially
the corrections of energy levels which are of order $\a^4 m_t$ or numerically
comparable to that order, and which have no counterpart in the 'relativistic'
corrections of QED. In contrast to previous computations we give analytic
expressions for all contributions considered in our present work, hopefully
preparing the ground for further similar calculations.


title: Formation of Topological Defects at First Order Phase Transitions

abstract:
  We analyze the evolution of scalar and gauge fields during first order phase
transitions and show how the Kibble mechanism for the formation of topological
defects emerges from the underlying dynamics, paying particular attention to
problems posed by gauge invariance when a local symmetry is spontaneously
broken. We discuss also the application of the mechanism to semilocal defects
and electroweak strings.


title: Technidilaton Phenomenology and Prospects for Production

abstract:
  An effective Lagrangian for the technidilaton and its interactions with
matter is constructed. Properties of the technidilaton are compared with those
of the Higgs boson. Technidilaton decays and production channels are
investigated. Main technidilaton decays are suppressed compared to the Higgs
boson and the most important production mechanism is due to gluon fusion.
Prospects for technidilaton production and detection at $e^+e^-$ colliders and
the SSC are examined. LEP 1, LEP 2 and SSC can find or rule out a technidilaton
with a mass up to $10~GeV$, $40~GeV$ and $230~GeV$ respectively.


title: The Origin of the Sphaleron Dipole Moment

abstract:
  By providing a suitable definition of the electromagnetic field off the Higgs
vacuum, we show that within the sphaleron there is a monopole-antimonopole pair
with quantized charges, and a loop of electromagnetic current. On integration
of the relevant charges and currents over the interior in the limit of small
$\Theta_W$, we recover the standard formula for the sphaleron dipole moment.


title: Searching for Supersymmetry in High-Energy Photon-Proton Scattering

abstract:
  We investigate the possibility to search for supersymmetry in the scattering
of protons and Compton back-scattered laser light. We evaluate the cross
sections for inelastic and elastic production of wino pairs for different
electron-proton c.m.s. energies. For $\sqrt{s}=1\ TeV$ the cross section
exceeds $1\ fb$ for $m_w<190\ GeV$.


title: An Estimate of Jet Activity in $t\bar t$ Events

abstract:
  We present a calculation of jet activity associated with pair production of
top quarks at hadron colliders and supercolliders. Our approach is based upon a
merger of $2\rightarrow 3$ matrix elements with initial and final state parton
showers. We tabulate expected multi-jet rates in $t\bar t$ events, and compare
with ${\cal O}(\alpha_s^3 )$ matrix element results and parton showers based
upon $2\rightarrow 2$ subprocesses. The merged calculation includes the correct
matrix element for the first leg of the parton shower, but also includes the
effects of approximate all-orders quark and gluon emission. We also evaluate
expected jet activity in top pair events at hadron supercolliders; in
particular, a comparison of the jet activity in the far forward region is made.
It is found that the merged calculation yields more jet activity in the forward
region than pure matrix element estimates, but also more jet activity in the
central region. This can be important for background calculations to
$H\rightarrow WW$ and strong $WW$ scattering processes.


title: Neutralino-Nucleon Scattering Revisited

abstract:
  We present a detailed discussion of the elastic scattering of a
supersymmetric neutralino off a nucleon or nucleus, with emphasis on the
spin--independent interaction. We carefully treat QCD effects on the squark
exchange contribution. In particular, we identify a class of terms that survive
even in the absence of mixing in both the neutralino and squark sectors; the
corresponding quark and gluon operators also appear in analyses of
deep--inelastic lepton--nucleon scattering (``twist--2 operators''), so their
hadronic matrix elements are well known. We also re--emphasize the importance
of mixing between the superpartners of left-- and right--handed quarks, and of
the contribution from the heavier scalar Higgs boson. We use our refined
calculation of the scattering amplitude to update predictions of signal rates
for cosmic relic neutralino searches with Germanium detectors. In general the
counting rate varies strongly with the values (even the signs) of model
parameters; typical results lie between a few times $10^{-4}$ and a few times
$10^{-1}$ events/(kg$\cdot$day).


title:
Constraints on the Higss and Top Quark Masses From Effective Potential
  and Non-Commutative Geometry

abstract:
  We consider the standard model in the formulationo of non-commutative
geometry, for a Euclidean space-time consisting of two copies. The electroweak
scale is set by the vacuum expectation value of a scalar field and is
undetermined at the classical level. By adding the Coleman-Weinberg effective
potential, that scale turns out to be fixed. Provided that the renormalized
form of the Lagrangian maintains the vanishing of the cosmological constant, we
show that the only solutions for the minimization equations of the total
potential occur in the narrow band $146.2 \le m_t \le 147.4 $ Gev for the top
quark mass, with the corresponding Higgs mass $117.3 \le m_H\le 142.6$ Gev.


title: Thermalization of the Higgs Field at the Electroweak Phase Transition

abstract:
  The thermalization rate for long wavelength fluctuations in the Higgs field
is calculated from the imaginary part of the finite temperature effective
action in the unbroken phase of the Standard Model. We use improved propagators
including a resummation of hard thermal loops. The thermalization rate is
computed at one loop level, but an estimate of the two--loop contribution
appears to give an indication that they are comparable to the one--loop result
for small thermal higgs mass. We show also that the Higgs field fluctuations
are likely to thermalize very fast compared with the electroweak phase
transition time.


title:
The SuperWorlds of SU(5) and SU(5)xU(1): A Critical Assessment and
  Overview

abstract:
  We present an overview of the simplest supergravity models which enforce
radiative breaking of the electroweak symmetry, namely the minimal $SU(5)$
supergravity model and the class of string-inspired/derived supergravity models
based on the flipped $SU(5)\times U(1)$ structure supplemented by a minimal set
of additional matter representations such that unification occurs at the string
scale ($\sim10^{18}\GeV$). These models can be fully parametrized in terms of
the top-quark mass, the ratio $\tan\beta=v_2/v_1$, and three supersymmetry
breaking parameters ($m_{1/2},m_0,A$). The latter are chosen in the minimal
$SU(5)$ model such that the stringent constraints from proton decay and
cosmology are satisfied. In the flipped $SU(5)$ case we consider two
string-inspired supersymmetry breaking scenaria: $SU(N,1)$ no-scale
supergravity and a dilaton-induced supersymmetry breaking scenario. Both imply
universal soft supersymmetry breaking parameters: $m_0=A=0$ and
$m_0=\coeff{1}{\sqrt{3}}m_{1/2}, A=-m_{1/2}$ respectively. We present a
comparative study of the sparticle and Higgs spectra of both flipped $SU(5)$
models and the minimal $SU(5)$ model and conclude that all can be partially
probed at the Tevatron and LEPII (and the flipped models at HERA too). In both
flipped $SU(5)$ cases there is a more constrained version which allows to
determine $\tan\beta$ in terms of $m_t,m_{\tilde g}$ and which leads to much
sharper and readily accessible experimental predictions. We also discuss the
prospects for indirect experimental detection: a non-trivial fraction of the
parameter space of the flipped $SU(5)$ models is in conflict with the present
experimental allowed range for the $b\to s\gamma$ rare decay mode, and the
one-loop electroweak radiative corrections imply the 90\% CL upper bound


title: Spontaneous Baryogenesis with Observable CP Violation

abstract:
  Using a left-right symmetric model with Spontaneous CP Violation and the
hypothesis of a weakly first order electroweak phase transition we derive a
relation between the produced baryon asymmetry and the observed parameter
$\varepsilon$, describing CP violation in the $K$ system.


title:
Tree amplitudes at multiparticle threshold in a model with softly broken
  $O(2)$ symmetry

abstract:
  Tree amplitudes of the production of two kinds of scalar particles at
threshold from one virtual particle are calculated in a model of two scalar
fields with $O(2)$ symmetric quartic interaction and unequal masses. These
amplitudes exhibit interesting factorial and exponential behaviour at large
multiplicities. As a by-product we observe that the kinematically allowed decay
of one real particle into $n$ real particles of another kind, all at rest, has
zero tree amplitude in this model for $n>2$.


title: The Strong CP Problem, String Theory and the Nelson-Barr Mechanism

abstract:
  We review recent work on the strong CP problem in the context of realistic
string-inspired models. We discuss the various solutions, review the conjecture
that CP is generally a gauged discrete symmetry in string theory and then
consider models of the Nelson-Barr type. We note that squark non-degeneracy
spoils the Nelson-Barr structure at the one loop level. We stress that string
theory expectations, as well as naturalness arguments, make it very difficult
to avoid the constraints on non-degeneracy.


title: CP and CPT Violation: Status and Prospects

abstract:
  I review the status of CP violating phenomena and CPT tests in the neutral
Kaon system. Comparisons of present data with the expectations of the Cabibbo
Kobayashi Maskawa model are presented, with particular emphasis being focused
on the role of the theoretical uncertainties in this comparison. In addition,
novel tests of CPT at DAFNE and Fermilab are briefly discussed.


title: Heavy Hadron Weak Decay Form Factors to Next-to-Leading Order in 1/m

abstract:
  Based on the short-distance expansion of currents in the heavy quark
effective theory, we derive the exact expressions for the heavy-to-heavy meson
and baryon weak decay form factors to order $1/m_Q$ in the heavy quark
expansion, and to all orders in perturbation theory. We emphasize that the
Wilson coefficients in this expansion depend on a kinematic variable $\bar w$
that is different from the velocity transfer $w=v\cdot v'$ of the hadrons. Our
results generalize existing ones obtained in the leading-logarithmic
approximation. Some phenomenological applications are briefly discussed.


title: Two-loop renormalization of gaugino mass in supersymmetric gauge model

abstract:
  We study the two-loop renormalization group equation for the running gaugino
mass in the supersymmetric gauge theory. We find that both in the \msbar and
\drbar renormalization schemes, the well-known proportionality of the runnings
of the gaugino mass and the gauge coupling constant is violated at the two-loop
order, even in models with vector supermultiplets only. Scheme dependence of
the running gaugino mass is clarified.


title:
Effect of Hairpin Diagram on Two-body Nonleptonic B Decays and CP
  Violation

abstract:
  A careful quark-diagram analysis shows that a number of two-body nonleptonic
$B$ decays can occur through the so-called hairpin diagram, a QCD loop-induced
graph different from penguin in final-state hadronization of valence quarks.
Using the two-loop renormalization-group-improved effective Hamiltonian and the
naive factorization approximation, we demonstrate the effect of the hairpin
diagram on decay rates and $CP$ asymmetries for a few interesting channels such
as $B^{0}_{d},\bar{B}^{0}_{d} \rightarrow \psi K_{S}$ and
$B^{\pm}_{u}\rightarrow \phi K^{\pm}$. Branching ratios of some pure hairpin
decay modes, e.g., $B^{-}_{u}\rightarrow \phi \pi^{-},\phi \rho^{-}$ and
$\bar{B}^{0}_{d}\rightarrow \phi \pi^{0},\phi \rho^{0}, \phi \omega, \phi
\eta,$ etc., are estimated to be on the order of $10^{-7}$.


title: Majorana Neutrino Masses Can Save One Family Technicolour

abstract:
  We make non perturbative estimates of the electroweak radiative correction
parameter $S$ in dynamical symmetry breaking models with Majorana neutrino
masses. The Majorana masses are treated as perturbations to a Non Local Chiral
Model of the strong interactions. We argue that parameter ranges exist that
would allow realistic values of $S$ and $T$ in one family Technicolour models.


title:
A New Gauge for Computing Effective Potentials in Spontaneously Broken
  Gauge Theories

abstract:
  A new class of renormalizable gauges is introduced that is particularly well
suited to compute effective potentials in spontaneously broken gauge theories.
It allows one to keep free gauge parameters when computing the effective
potential from vacuum graphs or tadpoles without encountering mixed propagators
of would-be-Goldstone bosons and longitudinal modes of the gauge field. As an
illustrative example several quantities are computed within the Abelian Higgs
model, which is renormalized at the two-loop level. The zero temperature
effective potential in the new gauge is compared to that in $R_\xi$ gauge at
the one-loop level and found to be not only easier to compute but also to have
a more convenient analytical structure. To demonstrate renormalizability of the
gauge for the non-Abelian case, the renormalization of an SU(2)-Higgs model
with completely broken gauge group and of an SO(3)-Higgs model with an unbroken
SO(2) subgroup is outlined and renormalization constants are given at the
one-loop level.


title: q\bar q$ bound states in the Bethe-Salpeter formalism

abstract:
  We solve the Bethe-Salpeter equation in order to calculate the spectrum of
pseudoscalar, vector and scalar meson bound states for light as well as heavy
quarks, extending our previous calculation of pseudoscalar mesons. The fermion
propagators appearing in the equation are obtained by solving the
Schwinger-Dyson equation consistently with the Bethe-Salpeter equation, a
procedure necessary for demonstrating the Goldstone nature of the pion in the
chiral limit.
  We probe in our calculations a model for the gluon propagator which leads to
the expected three dimensional potential in configuration space, while
maintaining its known ultraviolet behavior. Our procedure provides a unified
description of both the light and heavy mesons and obeys known relations
derived on the basis of current algebra for light quarks and nonrelativistic
analysis for heavy quarks. The results are in good agreement with experiment
for the mass spectrum and for the pseudoscalar mesons' decay constants. We also
calculate electromagnetic and isospin mass splittings for these mesons.


title: $B_c$ Mesons Production at Hadron Colliders by Heavy Quark Fragmentation

abstract:
  We present a reliable estimate on the production rate of $B_c$ mesons in $1S$
and $2S$ states in the large transverse momentum region at hadronic colliders
using heavy quark fragmentation functions derived within the framework of
perturbative QCD. We also present the transverse momentum distribution for the
$B_c$ mesons. The production rate is large enough for the $B_c$ mesons to be
identified at the Tevatron. At the SSC/LHC the rate is so large that their
properties can be studied in details.


title: Bounding Anomalous Gauge-Boson Couplings

abstract:
  In this version we have corrected some minor errors in the tables, corrected
typos, and added a reference. We have also updated our comparison with earlier
workers. Figures are now included as uuencoded compressed tar files.


title:
Bounds from Stability and Symmetry Breaking on Parameters in the
  Two-Higgs-Doublet Potential

abstract:
  The most general $SU(2)\times U(1)_Y$-symmetric quartic potential with two
Higgs doublets, subject to an only softly broken discrete symmetry
$(\phi_1,\phi_2)\to(-\phi_1,\phi_2)$, is considered. At tree-level, analytic
bounds on the parameters are derived that ensure a stable vacuum, breaking
$SU(2)\times U(1)_Y$ down to $U(1)_{em}$.


title:
Higgs Production in Association with a Vector Boson Pair at Future e+ e-
  Colliders

abstract:
  We study Higgs boson production in association with a pair of electroweak
vector bosons ($WW,ZZ,Z\gamma$) at future $\epem$ colliders in the framework of
the Standard Model. Total cross sections and distributions for the
intermediate-mass Higgs are presented, with special emphasis on the Next Linear
Collider (NLC) case operating at a centre-of-mass energy $\sqrt{s} \simeq 500$
GeV, where the cross sections turn out to be more favourable than in
larger-$\sqrt{s}$ collisions. We find that with an integrated luminosity of 20
fb$^{-1}$ there is a sizeable event rate for the $HWW$ and $HZ\gamma$ (with a
high $p_T^{\gamma}$) channels, while a larger integrated luminosity is needed
to study the $HZZ$ production. We take into account various backgrounds,
notably top-pair and triple vector-boson production, and show ways to
significantly reduce their effects.


title: Conditions on supersymmetry soft-breaking terms from GUTs

abstract:
  We study the effect of integrating out the heavy fields in a supersymmetric
GUT which does not contain small mass parameters in the limit of exact
supersymmetry. The trilinear ($A$) and bilinear ($B$) coefficients of the
supersymmetry soft-breaking terms of the low-energy effective theory are
related in a simple and model-independent way to those of the underlying
theory. {}From these relations, we obtain the bound $|B|\ge 2$, which, together
with the requirements of stability of the potential and electroweak symmetry
breaking, imposes severe constraints on the space of allowed supersymmetric
parameters. In models based on supergravity with a flat K\"ahler metric, we
obtain $B=2$, instead of the relation $B=A-1$ usually used in phenomenological
applications. The low-energy theory contains also a supersymmetric mass term
$\mu$ for the two Higgs doublets, which is of the order of the
supersymmetry-breaking scale.


title:
Measurement of the Strange Quark Distribution Function in W + Charm
  Quark Events

abstract:
  We investigate the prospects of measuring the strange quark distribution
function at the Tevatron, using $W$ plus charm quark events. The $W$ plus charm
quark signal produced by strange quark--gluon fusion, $sg\rightarrow W^-c$ and
$\bar sg\rightarrow W^+\bar c$, is approximately 5\% of the inclusive $W+1$ jet
cross section for jets with a transverse momentum $p_T(j)>10$~GeV. We study the
sensitivity of the $W$ plus charm quark cross section to the parametrization of
the strange quark distribution function, and evaluate the various background
processes. Strategies to identify charm quarks in CDF and D$0\llap/$ are
briefly described.


title:
Nuclear Shell Model Calculations of Neutralino-Nucleus Cross Sections
  for Silicon 29 and Germanium 73

abstract:
  We present the results of detailed nuclear shell model calculations of the
spin-dependent elastic cross section for neutralinos scattering from \si29 and
\ge73. The calculations were performed in large model spaces which adequately
describe the configuration mixing in these two nuclei. As tests of the computed
nuclear wave functions, we have calculated several nuclear observables and
compared them with the measured values and found good agreement. In the limit
of zero momentum transfer, we find scattering matrix elements in agreement with
previous estimates for \si29 but significantly different than previous work for
\ge73. A modest quenching, in accord with shell model studies of other heavy
nuclei, has been included to bring agreement between the measured and
calculated values of the magnetic moment for \ge73. Even with this quenching,
the calculated scattering rate is roughly a factor of 2 higher than the best
previous estimates; without quenching, the rate is a factor of 4 higher. This
implies a higher sensitivity for germanium dark matter detectors. We also
investigate the role of finite momentum transfer upon the scattering response
for both nuclei and find that this can significantly change the expected rates.
We close with a brief discussion of the effects of some of the non-nuclear
uncertainties upon the matrix elements.


title: Real time thermal propagtors for massive gauge bosons

abstract:
  We derive Feynman rules for gauge theories exhibiting spontaneous symmetry
breaking using the real-time formalism of finite temperature field theory. We
also derive the thermal propagators where only the physical degrees of freedom
are given thermal boundary conditions. We analyse the abelian Higgs model and
find that these new propagators simplify the calculation of the thermal
contribution to the self energy.


title: Heavy Quark Effective Theory at Large Orders in $1/m$

abstract:
  The existing derivations of a heavy quark effective theory (HQET) are
analyzed beyond the next-to-leading order in $1/m$. With one exception they are
found to be incorrect. The problem is a wrong normalization of the heavy quark
field in the effective theory. We argue that the correct effective theory
should be given by a Foldy--Wouthuysen type field transformation to all orders
in $1/m$. The renormalization of the resulting Lagrangian to order $1/m^2$ is
performed allowing for inclusion of effects arising through vacuum
polarization. Our results for the anomalous dimensions disagree with the
existing ones. Some applications are considered.


title:
Cosmological Constraint on the Scale of the Supersymmetric Singlet
  Majoron

abstract:
  In a SUSY theory with a spontaneously broken global symmetry, G, if the scale
of SUSY breaking, $M_s$ is smaller than the scale $M_G$ of the global symmetry,
the Nambu-Goldstone boson, $\chi$ is accompanied by two massive superpartners (
a fermionic, $\Psi_\chi$ and a scalar $\sigma_\chi$) with mass of order $M_s$.
Cosmological considerations imply stringent constraints on the couplings of
$\Psi_\chi$ and $\sigma_\chi$. Application of these considerations to the
supersymmetric singlet Majoron model leads to an upper limit on the scale
$V_{BL}$ of global $U(1)_{B-L}$ symmetry to be less than $10^4 GeV$, for
resonable values of parameters in the theory.


title: CP Violating Observables in $e^-e^+ \to W^-W^+$

abstract:
  We consider various integrated lepton charge-energy asymmetries and azimuthal
asymmetries as tests of CP violation in the process $e^-e^+ \to W^-W^+$. These
asymmetries are sensitive to different linear combinations of the CP violating
form factors in the three gauge boson $W^-W^+$ production vertex, and can
distinguish dispersive and absorptive parts of the form factors. It makes use
of purely hadronic and purely leptonic modes of $W$'s decays as well as the
mixed modes. The techniques of using the kinematics of jets or missing momentum
to construct CP--odd observables are also employed. These CP violating
observables are illustrated in the generalized Left-Right Model and the Charged
Higgs Model.


title:
Does $J/\psi \rightarrow \pi^{+} \pi^{-}$ fix the Electromagnetic Form
  Factor $F_{\pi}(t)$ at $t=M_{J/\psi}^2$?

abstract:
  We show that the $J/\psi \rightarrow \pi^{+} \pi^{-}$ decay is a reliable
source of information for the electromagnetic form factor of the pion at
$t=M_{J/\psi}^2=9.6 {\rm GeV}^2$ by using general arguments to estimate, or
rather, put upper bounds on, the background processes that could spoil this
extraction. We briefly comment on the significance of the resulting
$F_{\pi}(M_{J/\psi}^2)$.


title: Chiral-Symmetry and Strange Four-Quark Matrix Elements

abstract:
  We consider the matrix elements of the left-handed flavor-conserving
four-quark operators in the nucleon and pion states. Using chiral symmetry, we
derive relationships among these matrix elements. We argue that the $\Delta I =
1/2$ rule of hyperon and kaon non-leptonic weak decay implies possible large
strange-quark content in the nucleon and pion.


title:
Chiral-Odd and Spin-Dependent Quark Fragmentation Functions and their
  Applications

abstract:
  We define a number of quark fragmentation functions for spin-0, -1/2 and -1
hadrons, and classify them according to their twist, spin and chirality. As an
example of their applications, we use them to analyze semi-inclusive
deep-inelastic scattering on a transversely polarized nucleon.


title: A Simple Test for Non-Gaussianity in CMBR Measurements

abstract:
  We propose a set of statistics $S_q$ for detecting non-gaussianity in CMBR
anisotropy data sets. These statistics are both simple and, according to
calculations over a space of linear combinations of three-point functions,
nearly optimal at detecting certain types of non-gaussian features. We apply
$S_3$ to the UCSB SP91 experiment and find that the mean of the four frequency
channels is by this criterion strongly non-gaussian. Such an observation would
be highly unlikely in a gaussian theory with a small coherence angle, such as
standard ($n=1$, $\Omega_b = .05$, $h = .5$) inflation. We cannot conclude that
the non-gaussianity is cosmological in origin, but if we assume it due instead
to foreground contamination or instrumental effects, and remove the points
which are clearly responsible for the non-gaussian behavior, the rms of the
remaining fluctuations is too small for consistency with standard inflation.
Further data are needed before definitive conclusions may be drawn. Finally, we
generalize the ideas behind this statistic to other types of non-gaussian
behavior that might be detected in other experimental schemes.


title: Blois V: Summary Talk

abstract:
  Although we have a theory of strong interactions, its implications for the
physics of average hadron collisions, which is the focus of this series of
conferences, are far from obvious. QCD has nevertheless been a very powerful
guide and I will argue that a consensus description of ``soft" hadronic physics
is emerging at least at the phenomenological level, even though the message is
hidden by a myriad of competing models such as the Lipatov Pomeron, the jet
model, dual topological unitarization, etc. Understanding this physics is a
high priority not only because it is intrinsically interesting (e.g.\ the
search for chiral condensates or for point-like structure of the Pomeron), but
because it dictates the structure of the backgrounds and underlying events in
any hadron collider experiment. In the not so distant future most of particle
physics will rely on such machines and I will therefore emphasize issues
associated with the physics exploitation of future colliders (e.g.\ rapidity
gaps). This is also the first Blois meeting after HERA and the experiments have
already contributed significant novel information on the physics discussed at
this meeting.


title:
Measuring the Longitudinally Polarized Proton Gluon Distribution using
  Photoproduction Processes

abstract:
  Little information is known about the polarization of gluons inside a
longitudinally polarized proton. We investigate the sensitivity of
photoproduction experiments with both beam and target longitudinally polarized
to the polarization of the gluon distribution in the proton. We study the
photoproduction of jets and heavy quarks and conclude that they are both
sensitive to the gluon polarization.


title: W, Z and Higgs Scattering at SSC Energies

abstract:
  The scattering of $W$, $Z$ and Higgs bosons in the Standard Model is
investigated in the region $s,m_H^2\gg m_W^2$ with no restrictions on relative
sizes of $s$ and $m_H^2$, so that our results are applicable at energies below
as well as above $2m_H$. We have calculated, with the inclusion of the full
one-loop corrections, the scattering matrix between the states $W_L^+W_L^-$,
$Z_LZ_L$ and $HH$, and computed the S-wave amplitudes as functions of the
center-of-mass energy $\sqrt{s}$ for $m_H=$500~GeV and 1000~GeV. The apparent
violation of unitarity is avoided by unitarizing the amplitudes by the K-matrix
and the Pad\'e methods. For the detection of the Higgs boson through gauge
boson scattering in $pp$ collisions, we have used the unitarized amplitudes to
obtain the invariant-mass distributions for the final $W_L^+W_L^-$ and $Z_LZ_L$
pairs at the SSC energy of $\sqrt{s}=$40~TeV by means of the effective-W
approximation.


title: High Energy Neutrino Telescopes Detect Supernovae

abstract:
  We have simulated the response of a high energy neutrino telescope to the
stream of low energy neutrinos produced by a supernova. The nominal threshold
of such detectors is in the GeV energy range. The passage of a large flux of
MeV neutrinos during a period of seconds will nevertheless be detected as an
excess of single counting rates in all individual optical modules. Detectors
under construction, which consist of roughly 200 modules, will be able to
detect a galactic supernova at or above the 5 $\sigma$ level. The rate of fake
signals is, however, too large for the telescope to serve as a neutrino watch.
Such capability requires detectors with roughly 3 times the number of optical
modules, thus within easy reach of the next generation detectors.


title: Baryon-Pion Couplings from Large-N QCD

abstract:
  We derive a set of consistency conditions for the pion-baryon coupling
constants in the large-N limit of QCD. The consistency conditions have a unique
solution which are precisely the values for the pion-baryon coupling constants
in the Skyrme model. We also prove that non-relativistic $SU(2N_f)$ spin-flavor
symmetry (where $N_f$ is the number of light flavors) is a symmetry of the
baryon-pion couplings in the large-N limit of QCD. The symmetry breaking
corrections to the pion-baryon couplings vanish to first order in $1/N$.
Consistency conditions for other couplings, such as the magnetic moments are
also derived.


title: 1/N Corrections to the Baryon Axial Currents in QCD

abstract:
  We prove that the 1/N corrections to the baryon axial current matrix elements
are proportional to their lowest order values. This implies that the first
correction to axial current coupling constant ratios vanishes, and that the
$SU(2N_f)$ spin-flavor symmetry relations are only violated at second order in
1/N.


title:
Light Quark Spin-Flavor Symmetry for Baryons Containing a Heavy Quark in
  Large N QCD

abstract:
  The couplings and interactions of baryons containing a heavy quark are
related by light quark spin-flavor symmetry in the large $N$ limit. The single
pion coupling constant which determines all heavy quark baryon-pion couplings
is equal to the pion coupling constant for light quark baryons. Light quark
symmetry relations amongst the baryon couplings are violated at order $1/N^2$.
Heavy quark spin-flavor symmetry is used in conjunction with large $N$ light
quark spin-flavor symmetry to determine the couplings of the degenerate
doublets of heavy quark baryons.


title: Baryon Hyperfine Mass Splittings in Large N QCD

abstract:
  The hyperfine mass splittings of baryons in large $N$ QCD are proved to be
proportional to ${\bf J}^2$. Hyperfine mass splittings are first allowed at
order $1/N$ in the $1/N$ expansion.


title:
Hyperfine Mass Splittings of Baryons Containing a Heavy Quark in Large N
  QCD

abstract:
  The hyperfine mass splittings of baryons containing a heavy quark are derived
at leading order in large $N$ QCD. Hyperfine splittings either preserve or
violate heavy quark spin symmetry. Previous work proves that the splittings
which preserve heavy quark spin symmetry are proportional to ${\bf J}^2$ at
order $1/N$, where $J$ is the angular momentum of the light degrees of freedom
of the baryon. This work proves that the splittings which violate heavy quark
spin symmetry are proportional to ${\bf J} \cdot {\bf S_Q}$ at order $1/(N
m_Q)$ in the $1/N$ and $1/m_Q$ expansions.


title: Vacuum QCD and new information on nucleon structure functions

abstract:
  It is shown, that specific chirality and flavor properties of the
instanton-induced interaction allow us to explain the observed violation
Ellis-Jaffe and Gottfried sum rules. A large value of these violations
originates from the anomalous growth of the instanton-induced interaction
between quarks at high energy. The new sum rule which connect the values of
violations of Ellis-Jaffe and Gottfried sum rules have been obtained.


title:
Differential Distributions in Semileptonic Decays of the Heavy Flavors
  in QCD

abstract: Several references added, typos corrected.


title: Unitarization of Structure Functions at Large ${\bf 1/x}$

abstract:
  We discuss the effects of the $s$-channel unitarization on the $x$ and
$Q^{2}$ dependence of structure functions. The unitarization is implemented at
the level of photoabsorption cross sections by resorting to the light--cone
wave functions of virtual photons and to the diagonalization property of the
scattering matrix in a basis of Fock states of the photon with fixed transverse
size. Triple pomeron effects are also explicitly taken into account. We find
large unitarity corrections to the structure functions at $x < 10^{-2}$. The
results are in very good agreement with the existing NMC and the preliminary
HERA data.


title: Light Stop and the $b\rightarrow s\gamma$ Process

abstract:
  A constraint from $b\rightarrow s\gamma$ process to the minimal
supersymmetric standard model is derived in the light stop region where the
coupling between the lighter stop and the $Z^0$ boson vanishes due to the
left-right mixing of the stop states. It is pointed out that although some
region in the parameter space is excluded from this process there remains a
large parameter space where the amplitude of the $b\rightarrow s\gamma$ is
suppressed due to partial cancellation between different diagrams. Stop as
light as 20 GeV is still viable from the $b\rightarrow s\gamma$ constraint.


title: Beyond the black disk limit

abstract:
  We consider consequences of violation of the black disk limit possibly
revealed by the new CDF measurements of the total, elastic and diffractive
cross--sections.


title: Hadrons and Glue at a Tau-Charm Factory

abstract:
  I discuss the special opportunities that a Tau-Charm Factory offers for
identifying gluonic excitations, hybrid charmonium and other exotic hadronic
states. (Invited talk at TCF Workshop, Marbella, 1-6June)


title: Searching for Exotic Tau Decays

abstract:
  We discuss the potential of $\tau$-charm and B factories for the search of
new physics through the study of rare $\tau$ decays. We consider decays that
involve the violation of lepton flavour conservation. Such decays bear a close
relationship to the physics of neutrino mass and the properties of the lepton
sector of the electroweak theory.


title: Thermal Fluctuations at Second Order Phase Transitions

abstract:
  We construct a new coarse-grained effective potential which enables us to
estimate the probabilities of thermal fluctuations above an arbitrary threshold
at different length scales.


title: Three lepton decay modes of the proton

abstract:
  We consider the three lepton decay modes of the proton within the proton
decay interpretation of the atmospheric neutrino anomaly. We construct higher
dimensional operators in the framework of the standard model. The operators
which allow the particularly interesting decay mode are of dimension 10
involving $SU(2)_L$ non-singlet higgs. We show how these operators can be
comparable to the dimension 9 operators. We then present a simple left-right
symmetric model which can give rise to the desired proton decay modes of the
right order of magnitude.


title: Probing the Scalar Sector in $e^+ e^- \to Z \phi$

abstract:
  We study possible deviations from the Standard Model in the reaction $e^+e^-
\to Z\phi$, where $\phi$ denotes a spinless neutral boson. We show how the $Z$
decay angular correlation can be used to extract detailed information on the
$\phi$ couplings, such as the parity of $\phi$, radiatively induced form factor
effects and possible CP violation in the scalar sector.


title: Single $W$-Boson Production in $e\gamma$ Collisions

abstract:
  We studied single $W$ boson production in high energy $e\gamma$ collisions
and the sensitivity of various observables to the $WW\gamma$ vertex. We
included gauge boson decay to final state fermions and all contributions to the
same final state. The contributions of the non-resonant diagrams and their
interference with the resonant gauge boson production diagrams give significant
contributions which should not be neglected. We present results for $W$
production at a 500 GeV $e^+e^-$ collider with the photon spectra obtained from
a backscattered laser.


title:
Polarization Effects in Scalar Lepton Production at High Energy
  $\gamma\gamma$ Colliders

abstract:
  We investigate the charged scalar lepton production processes
$\gamma\gamma\to{\widetilde{\ell}}^{+}{\widetilde{\ell}}^{-}$ at high energy
$\gamma\gamma$ colliders in the framework of the minimal supersymmetric
standard model (MSSM). Here the high energy $\gamma$ beams are obtained by the
backward Compton scattering of the laser flush by the electron in the basic
linear TeV $ee$ colliders. We consider the polarization of the laser photons as
well as the electron beams. Appropriate beam polarization could be effective to
enhance the cross section and to extract the signal from the dominant
background $\gamma\gamma\to W^{+}W^{-}$.


title: Casimir Effect of Strongly Interacting Scalar Fields

abstract:
  Non-trivial $\phi ^{4}$-theory is studied in a renormalisation group
invariant approach inside a box consisting of rectangular plates and where the
scalar modes satisfy periodic boundary conditions at the plates. It is found
that the Casimir energy exponentially approaches the infinite volume limit, the
decay rate given by the scalar condensate. It therefore essentially differs
from the power law of a free theory. This might provide experimental access to
properties of the non-trivial vacuum. At small interplate distances the system
can no longer tolerate a scalar condensate, and a first order phase transition
to the perturbative phase occurs. The dependence of the vacuum energy density
and the scalar condensate on the box dimensions are presented.


title: The $W$ Boson Loop Background to H -> ZZ at Photon-photon Colliders

abstract:
  We have performed a complete one-loop calculation of $\gamma \gamma
\rightarrow ZZ$ in the Standard Model, including both gauge bosons and fermions
in the loop. We confirm the large irreducible continuum background from the
$W$-boson loop found by Jikia. We have included the photon-photon luminosity,
and find that the continuum background of transverse $Z$ boson pairs prohibits
finding a heavy Higgs with mass $\gtap 350$ GeV in this decay mode.


title: Quark Model Form Factors for Heavy Quark Effective Theory

abstract:
  We show how both the spectroscopy of heavy-light hadrons and the slope of the
Isgur-Wise function can be simultaneously fitted when Heavy Quark Effective
Theory is matched onto dynamical quark models, including careful treatment of
wigner rotations. Working consistently to order $\vec{v}^2$ and using the
parameters from hadron spectroscopy as input, we determine the slope parameter
$\rho$ for s-wave transitions to be $1.19 \pm 0.02$. This agrees with the
emperical value for $b \rightarrow c$ transitions.


title: Unquenching the Rho Meson

abstract:
  Two-pion induced self-energy contributions to the $\rho$-meson mass are
examined in relation to the quenched approximation of QCD, where the physics
associated with two-pion intermediate states has been excluded from
vector-isovector correlation functions. Corrections to quenched QCD
calculations of the $\rho$-meson mass are estimated to be small at the order of
a few percent of the $\rho$-meson mass. The two-pion contributions display
nonanalytic behavior as a function of the pion mass as the two-pion cut is
encountered. The implications of this nonanalytic behavior in extrapolations of
full QCD calculations are also discussed. We note that for full QCD, the error
made in making a linear extrapolation of the $\rho$ mass, neglecting
nonanalytic behavior, increases as one approaches the two-pion cut.


title: Chiral Sum Rules and Their Phenomenology

abstract:
  We present an analysis of four sum rules, each based on chiral symmetry and
containing the difference $\rho_{\rm V}(s) - \rho_{\rm A}(s)$ of isovector
vector and axialvector spectral functions. Experimental data from tau lepton
decay and electron-positron scattering identify the spectral functions over a
limited kinematic domain. We summarize the status of the existing database.
However, a successful determination of the sum rules requires additional
content, in the form of theoretical input. We show how chiral symmetry and the
operator product expansion can be used to constrain the spectral functions in
the low energy and the high energy limits and proceed to perform a
phenomenological test of the sum rules.


title: Anatomy of a Weak Matrix Element

abstract:
  Although the weak nonleptonic amplitudes of the Standard Model are
notoriously difficult to calculate, we have produced a modified weak matrix
element which can be analyzed using reliable methods. This hypothetical
nonleptonic matrix element is expressible in terms of the isovector vector and
axialvector spectral functions $\rho_{\rm V}(s)$ and $\rho_{\rm A}(s)$, which
can be determined in terms of data from tau lepton decay and $e^+ e^-$
annihilation. Chiral symmetry and the operator product expansion are used to
constrain the spectral functions respectively in the low energy and the high
energy limits. The magnitude of the matrix element thus determined is compared
with its `vacuum saturation' estimate, and in the future may be accessible with
lattice calculations.


title: Isospin Multiplet Structure in Ultra--Heavy Fermion Bound States

abstract:
  The coupled Bethe--Salpeter bound state equations for a $Q\bar Q$ system,
where $Q=(U,D)$ is a degenerate, fourth generation, super--heavy quark doublet,
are solved in several ladder approximation models. The exchanges of gluon,
Higgs and Goldstone modes in the standard model are calculated in the
ultra--heavy quark limit where weak $\gamma, W^\pm$ and $Z^0$ contributions are
negligible. A natural $I=0$ and $I=1$ multiplet pattern is found, with large
splittings occuring between the different weak iso--spin states when $M_Q$, the
quark masses, are larger than values in the range $0.4 TeV<M_Q<0.8 TeV$,
depending on which model is used. Consideration of ultra--heavy quark lifetime
constraints and $U-D$ mass splitting constraints are reviewed to establish the
plausibility of lifetime and mass degeneracy requirements assumed for this
paper.


title: Flavor changing neutral currents in $SU(3)\otimes U(1)$ models

abstract:
  We consider flavor changing neutral current effects coming from the $Z'$
exchange in 3-3-1 models. We show that the mass of this extra neutral vector
boson may be less than 2 TeV and discuss the problem of quark family
discrimination.


title:
Optimization of R(e+e-) and "Freezing" of the QCD Couplant at Low
  Energies

abstract:
  The new result for the third-order QCD corrections to R_{e^+e^-}, unlike the
old, incorrect result, is nicely compatible with the
principle-of-minimal-sensitivity optimization method. Moreover, it leads to
infrared fixed-point behaviour: the optimized couplant, alpha_s/pi, for R(e+e-)
does not diverge at low energies, but "freezes" to a value 0.26 below about 300
MeV. This provides some direct theoretical evidence, purely from perturbation
theory, for the "freezing" of the couplant -- an idea that has long been a
popular and successful phenomenological hypothesis. We use the "smearing"
method of Poggio, Quinn, and Weinberg to compare the resulting theoretical
prediction for R(e+e-) with experimental data down to the lowest energies, and
find excellent agreement.


title: Review of constraints on fermion mixing

abstract:
  The constraints on the mixing angles of the standard fermions with new heavy
particles that can appear in many extensions of the electroweak theory are
reviewed. Some emphasis is put in distinguishing the effects of a mixing with
new states which transform in a non-canonical way with respect to $SU(2)\times
U(1)$ (left-handed singlets or right-handed doublets), from the effects of a
mixing with new states with standard quantum number assignments. Constraints
from flavor changing neutral current processes, as well as from flavor diagonal
and charged current experimental data are considered. New limits for lepton
flavor violating mixings are presented. By using the most recent results on the
$\tau$ mass, lifetime and branching ratios, updated limits on the mixing
parameters of the $\tau$ neutrino are derived. These limits are improved up to
a factor of 3, and no signals of deviation from the standard model predictions
are found. Limits on the mass of a $Z_1$ gauge boson from E$_6$, from the
absence of muon number violating processes are briefly discussed as well.


title:
Finite Temperature Effective Potential for the Abelian Higgs Model to
  the Order $e^4,\lambda^2$

abstract:
  A complete calculation of the finite temperature effective potential for the
abelian Higgs model to the order $e^4,\lambda^2$ is presented and the result is
expressed in terms of physical parameters defined at zero temperature. The
absence of a linear term is verified explicitly to the given order and proven
to survive to all orders. The first order phase transition has weakened in
comparison with lower order calculation, which shows up in a considerable
decrease of the surface tension. The only difference from the original version
is the splitting of some overlong lines causing problems with certain mailers.


title: Tau Kinematics from Impact Parameters

abstract:
  The momenta of $\tau$ decay products in the reaction $e^+e^-\to\tau^+\tau^-$
do not constrain the $\tau$ direction unambiguously. It is shown how the
measurement of tracks of hadrons from semileptonic $\tau$ decays, in particular
their relative impact parameters, allows to resolve this ambiguity.


title: Topics in Top Quark Physics

abstract:
  The status of top quark searches will be briefly reviewed. Theoretical
predictions for the top quark decay rate are presented including QCD and
electroweak radiative corrections. The possibilities for quarkonium searches at
an hadron collider will be discussed. The perspectives for top production at an
electron positron collider will be described in detail with emphasis on the
behavior of the cross section and decay distribution in the threshold region.