title:
Can $\gamma \gamma \rightarrow Z_L Z_L$ serve as a probe of the
  electroweak symmetry breaking sector ?

abstract:
  We investigate the feasibility of distinguishing among different models of
electroweak symmetry breaking by studying the process $\gamma \gamma
\rightarrow Z_L Z_L$ at photon colliders. For models with a low mass Higgs-like
scalar resonance, the $s$-channel contribution provides a distinct resonance
structure and large cross sections. However, the absence of a resonance
structure in the cross section for the above process does not discriminate in
principle between the existence of either a heavy Higgs boson or a vector
resonance of a non-linearly realized symmetry.


title: Testing Unified Supersymmetric Models

abstract:
  I define the Standard Supersymmetric Model (SSM) as the minimal
supersymmetric extension ofthe Standard Model with gauge coupling unification
and universal soft supersymmetry breaking at the unification scale. This
well-defined model has a five-dimensional space of unknown parameters ($m_t,
\tan\beta, m_{1/2}, m_0, A$). I outline the top-down and bottom-up methods of
solving this model. Thresholds may be treated either by dropping heavy
particles from the RGE's or by considering loop corrections to the vacuum
energy. Substantial regions of the parameter space are consistent with all
experimental constraints. I consider the relation of the SSM to more realistic
models such as supersymmetric $SU(5)$, Flipped $SU(5)\times U(1)$, the
String-Inspired Standard Model, and string-derived models. I briefly discuss
sparticle spectroscopy and flavor changing neutral currents (FCNC's) as sample
methods for determining the unknown parameters of the SSM, and discriminating
between the SSM and more realistic models.


title: Hadron Multiplicities in the Presence of Light Gluinos

abstract:
  We consider the effect of a massless gluino on the evolution of a parton
shower. The hadron multiplicity distribution is predicted to evolve as a
function of the collider energy in the same way as in the absence of gluinos,
except for a slower running of $\alpha_s$. A comparison of the predicted
average hadron multiplicity with experimental data is presented as a fit
constraining the values of the strong coupling constant at the $Z^0$ peak
$\alpha_s(m_Z)$ and the scale of the onset of hadronization $m_0$. It appears
that \lgl s are unlikely to be detected this way with less than 500 GeV of \cm\
energy.


title: Beauty and the Beast: What Lattice QCD Can Do for $B$ Physics

abstract:
  The role lattice QCD can play in $B$ physics is surveyed. We include results
for the decay constant, and discuss upcoming calculations of semileptonic form
factors and neutral-meson mixing. Together with experimental measurements,
these calculations can determine the unitarity triangle. Plenary talk presented
at the Workshop on $B$ Physics at Hadron Accelerators, Snowmass, Colo., 21
June--2 July, 1993.


title: Strongly interacting $W$ bosons and supersymmetry

abstract:
  We present arguments in favor of the idea that supersymmetric sigma models
with compact symmetric K\"ahler spaces as target manifolds have a second-order
phase transition in four dimensions. When applied to electroweak symmetry
breaking, these models then do not require a light Higgs boson or
techni-resonances but predict fermionic superpartners of longitudinal W's and Z
with masses at or below TeV scale. Presence of the phase transition leads to a
fractional-power energy dependence of fixed-angle scattering amplitude of
longitudinal W's and Z's at high energies.


title: Vacuum Misalignment in High Energy Collisions

abstract:
  We study a recent proposal to observe the disoriented chiral condensate in
high energy collisions. In order to produce a large fluctuation in pion
probability distribution, a large size of the correlated region is essential.
We study the role of the intrinsic symmetry breaking and suggest that a
negative (mass)^2 of mesons arising from a misaligned vacuum may be a candidate
for such a mechanism. We further point out a possibility to observe
unsuppressed strong $CP$ violation in the disoriented vacuum phase.


title:
Heavy Charged Lepton Pair Production Through Photon Fusion at Hadron
  Supercolliders

abstract:
  The pair production of charged heavy leptons via two photon fusion is
considered for hadron collisions at SSC and LHC energies. Rates for the
inelastic process $pp \rightarrow \gamma \gamma X \rightarrow L^+L^-X$ and the
elastic process $pp \rightarrow \gamma \gamma pp \rightarrow L^+L^- pp$ are
given in a Weizs\"{a}cker-Williams approximation and compared with production
via the gluon fusion and Drell-Yan mechanisms


title: {\it T}--odd Asymmetry in Chargino Pair Production Processes

abstract:
  $T$--violating asymmetry in chargino pair production processes is studied in
the Minimal Supersymmetric Standard Model. The asymmetry emerges at the tree
level in the production of two different charginos,and could be as large as of
order $10^{-2}$ in unpolarized electron beam experiments and $10^{-1}$ in
polarized electron beam experiments. In the pair production of the same
charginos, the asymmetry emerges through the electric and the weak "electric"
dipole moments of the charginos at the loop level. Its magnitude is of order
$10^{-4}$. The consistency with the electric dipole moments of the neutron and
the electron is also discussed.


title: On Deusons or Deuteronlike Meson-Meson Bound States

abstract:
  The systematics of deuteronlike two-meson bound states, {\it deusons}, is
discussed. Previous arguments that many of the present non-$q\bar q$ states are
such states are elaborated including, in particular, the tensor potential. For
pseudoscalar states the important observation is made that the centrifugal
barrier from the P-wave can be overcome by the $1/r^2$ and $1/r^3$ terms of the
tensor potential. In the heavy meson sector one-pion exchange alone is strong
enough to form at least deuteron-like $B\bar B^*$ and $B^*\bar B^*$ composites
bound by approximately 50 MeV, while $D\bar D^*$ and $D^*\bar D^*$ states are
expected near the threshold.


title: Aspects of Neutrino Cosmology

abstract:
  Primordial nucleosynthesis constrains the properties of light, stable
neutrinos. Apart from the well--known limit on the number of neutrino species,
there are also bounds on neutrino masses and magnetic moments. I discuss also
sterile neutrinos and neutrino propagation in a primordial magnetic field, such
as could be the origin of the observed galactic magnetic fields.


title: Octet-Baryon Form Factors in the Diquark Model

abstract:
  We present an alternative parameterization of the quark-diquark model of
baryons which particularly takes care of the most recent proton electric
form-factor data from the E136 experiment at SLAC. In addition to
electromagnetic form factors of the nucleon, for which good agreement with data
is achieved, we discuss the weak axial vector form factor of the nucleon as
well as electromagnetic form factors of $\Lambda$ and $\Sigma$ hyperons.
Technical advance in calculating the pertinent analytic expressions within
perturbative quantum chromodynamics is gained by formulating the wave function
of the quark-diquark system in a covariant way. Finally, we also comment on the
influence of Sudakov corrections within the scope of the diquark model.


title: How to Make Large Domains of Disoriented Chiral Condensate

abstract:
  Rajagopal and Wilczek have proposed that relativistic nuclear collisions can
generate domains in which the chiral condensate is disoriented. If sufficiently
large ({\it i.e.} nucleus sized), such domains can yield measurable
fluctuations in the number of neutral and charged pions. However, by numerical
simulation of the zero-temperature two-flavor linear sigma model, we find that
domains are essentially {\it pion} sized. Nevertheless, we show that large
domains can occur if the effective mesons masses are much lighter.


title:
Flavour Singlet ${\cal O}(\alpha_s^2 m_b^2/m_t^2)$ Corrections to the
  Partial Decay Rate $\Gamma(Z\rightarrow b\bar{b})$

abstract:
  We analytically compute the flavour singlet ${\cal O}(\alpha_s^2
m_b^2/m_t^2)$ radiative corrections to the partial decay rate
$\Gamma(Z\rightarrow b\bar{b})$. These corrections arise from anomalous
``double traingle'' diagrams containing a single $\gamma_5$ matrix inside each
of two closed fermion loops. They represent the next-to-leading term of the
asymptotic expansion in the inverse large top mass. As a byproduct of the
calculcation we confirm the results of B.Kniehl and J.H.K\"uhn for the flavour
singlet massless corrections \cite{KniKue90} as well as our previous ${\cal
O}(\alpha_s^2 m_b^2/M_Z^2)$ result \cite{CheKwi93}.


title: Radiatively induced electron and electron-neutrino masses

abstract:
  We consider, in the context of a 331 model with a single neutral right-handed
singlet, the generation of lepton masses. At zeroth order two neutrinos and one
charged lepton are massless, while the other leptons, two neutrinos and two
charged leptons, are massive. However the charged ones are still mass
degenerate. The massless fields get a mass through radiative corrections which
also break the degeneracy in the charged leptons.


title: Stability Analysis of Sum Rules for Compton Scattering

abstract:
  We perform a stability analysis of a recently proposed sum rule for pion
Compton scattering at fixed angle and moderate Mandelstam invariants. The sum
rule is found to be sensitive to the parameter $\lambda^2$, the contour radius
of a generalized Borel transform. A modified phenomenological model for the
continuum contribution is proposed to remove this dependence. It is shown that
the best value of the quark-hadron duality interval $s_0=0.6$ GeV$^2$ is close
to that in the form factor case ($s_0=0.7$ GeV$^2$). The application of this
new model to the pion form factor is examined. A comparison of our predictions
with those derived from a modified perturbative calculation including Sudakov
suppression is also briefly considered.


title:
The Fine-Tuning Problem of the Electroweak Symmetry Breaking Mechanism
  in Minimal SUSY Models

abstract:
  We calculate the region of the MSSM parameter space (i.e. $M_{1/2}$, $m_{0}$,
$\mu$, \ldots) compatible with a correct electroweak breaking and a realistic
top-quark mass. To do so we have included {\em all} the one-loop corrections to
the effective potential $V_{1}$ and checked their importance in order to obtain
consistent results. We also consider the fine-tuning problem due to the
enormous dependence of $M_{Z}$ on $h_{t}$ (the top Yukawa coupling), which is
substantially reduced when the one-loop effects are taken into account. We also
explore the reliability of the so-called "standard" criterion to estimate the
degree of fine-tuning. As a consequence, we obtain a new set of upper bounds on
the MSSM parameters or, equivalently, on the supersymmetric masses perfectly
consistent with the present experimental bounds.


title: Top Quark Production Cross Section

abstract:
  The production rate for top quarks at the Fermilab Tevatron is presented
using the exact order $\alpha_s^3$ corrected cross section and the resummation
of the leading soft gluon corrections in all orders of perturbation theory.


title:
On the Parton Interpretation of Quark Fragmentation into Hadrons with
  Different Spins

abstract:
  We calculate the spin density matrix of the hadron $h$ created via quark
fragmentation in the process $e^-e^+ \to q\bar q \to h + X$. In the case of
$h=\Lambda$ the experimental data could possibly elucidate the problem of
$s$-quark contribution to the spin of the $\Lambda$-hyperon, to be compared
with the case of the proton (``spin crisis''). Generally we find that for
hadrons with spin 1/2 the parton description, using only probabilities, works
much better than for vector particles, since in the former case the non
diagonal matrix elements of the hadron spin density matrix are suppressed by a
small factor $p_T/(z\sqrt s)$, where $p_T$ is the hadron transverse momentum
inside the jet.


title: An Asymptotically Free Phi4 Theory

abstract:
  The Phi4 theory in 4-epsilon dimensions has two fixed points, which coincide
in the limit epsilon->0. One is a Gaussian UV fixed point, and the other a
non-trivial IR fixed point. They lead to two different continuum field
theories. The commonly adopted IR theory is ``trivial,'' behaves like
perturbation theory, and suggests an upper bound on the Higgs boson mass. The
UV theory is asymptotically free, and does not impose a bound on the Higgs
mass. The UV continuum limit can also be reached in 4 dimensions with momentum
or lattice cutoff.


title:
Rigourous QCD Evaluation of Spectrum and Ground State Properties of
  Heavy Quarkonium Systems; with a Precision Determination of the bottom quark
  mass and of the eta-b mass

abstract:
  We present an evaluation of heavy quarkonium states (bottomium and
charmonium) from first principles. We use tree-level QCD (including
relativistic corrections) and the full one-loop potential; nonperturbative
effects are taken into account at the leading order through the contribution of
the gluon condensate <alpha_strong G^2>. We use the values Lambda_QCD= 200
(+80/-60) MeV and <alpha_s G^2> = 0.042 +/- 0.020 GeV^4, but we trade the value
of the quark mass by the masses of J/psi, Upsilon as input. We get good
agreement in what is essentially a zero parameter evaluation for the masses of
the 1S, 2S, 2P states of bottomium, the 1S state for charmonium, and the decay
Upsilon --> e^+ e^-. As outstanding result we obtain the precise determination
of the bottom quark mass (m_b) as well as an estimate of the hyperfine
splitting M(Upsilon)-M(eta_b): m_b(m_b^2) = 4387 (+7/-2) (-3/+4)
(+16/-32)(systematic) MeV, M(Upsilon)-M(eta_b) = 36 (+13/-7)(+3/-6)
(+11/-5)(syst.) MeV, the first error due to that in Lambda_QCD, the second to
that in <alpha_s G^2> (varied independently). For the c quark, we find
m_c(m_c^2)= 1306 (+21/-34)(-6/+6) MeV (up to systematic errors).


title: Three Successful Tests of Color Transparency and Nuclear Filtering

abstract:
  We review the theoretical formalism for hard exclusive processes in a nuclear
medium. Theory suggests that these processes will show the very interesting
phenomena of color transparency and nuclear filtering. The survival probability
in nuclear media has also been predicted to show a scaling behavior at large
momentum and large nuclear number. We show that all of these effects may have
already been seen experimentally.


title: The Light-flavor structure of the nucleon

abstract:
  Recent data on the Gottfried sum and less recent ones on the pion-nucleon
sigma term seem to disagree with naive parton-based expectations on the light
(i.e., up, down and strange) quark content of the nucleon. We show that these
discrepancies are resolved if nonperturbative contributions are included in the
analysis of the data. These appear both in the computation of matrix elements
of operators, and in their QCD scale dependence, and depend strongly on the
quantum numbers of the given state.


title: Initial State Radiation in Resolved Photon Interactions

abstract:
  After a brief review of recent data that confirm qualitative and quantitative
predictions for resolved photon processes, a possible problem with the
implementation of initial state showering in existing Monte Carlo event
generators is pointed out. It is argued that this is responsible for the rather
poor description of the jet rapidity distribution measured by the H1
collaboration at HERA.


title:
Instanton-Like Transitions at High Energies in (1+1) Dimensional Scalar
  Models

abstract:
  Instanton-like transitions (``shadow processes'') are considered in (1+1)
dimensional models with one scalar field whose potential is a quadratic well
with a cliff. The corresponding classical boundary value problem is solved, and
the semiclassical transition probabilities are found in a rather wide range of
energies and the numbers of initial particles.


title: Weak Hyperon Decays: Quark Sea and SU(3) Symmetry Breaking

abstract:
  An explanation of the difference in the values of the apparent $f/d$ ratios
for the S- and P- wave amplitudes of nonleptonic hyperon decays is proposed.
The argument is formulated in the framework of the standard pole model with
$(56,0^{+})$ ground-state and $(70,1^{-})$ excited baryons as intermediate
states for the P- and S- waves respectively. Under the assumption that the
dominant part of the deviation of $(f/d)_{P-wave}$ from $-1$ is due to large
quark sea effects, $SU(3)$ symmetry breaking in energy denominators is shown to
lead to a prediction for $(f/d)_{S-wave}$ which is in excellent agreement with
experiment. This corroborates our previous unitarity calculations which
indicated that the matrix elements $<B|H^{p.c.}_{weak}|B'>$ of the parity
conserving weak Hamiltonian between the ground-state baryons are characterized
by $f_{0}/d_{0} \approx -1.6$ or more. A brief discussion of the problem of the
relative size of S- and P- wave amplitudes is given. Finally, implications for
weak radiative hyperon decays are also discussed.


title: On Colour Rearrangement in Hadronic W$^+$W$^-$ Events

abstract:
  We discuss the possibility of colour rearrangement in $\ee \to \W^+ \W^- \to
\q_1 \qbar_2 \q_3 \qbar_4$ events, i.e.\ that the original colour singlets
$\q_1 \qbar_2$ and $\q_3 \qbar_4$ may be transmuted, for instance, into new
singlets $\q_1 \qbar_4$ and $\q_3 \qbar_2$. The effects on event properties
could be quite large if such a rearrangement would occur instantaneously, so
that gluon emission would be restricted to each of the new singlets separately.
We argue that such a scenario is unlikely for two reasons. Firstly, the $\W^+$
and $\W^-$ usually decay at separate times after the $\W^+\W^-$ production,
which leads to large relative phases for energetic radiation off the two
constituents of a rearranged system, and a corresponding dampening of the QCD
cascades. Secondly, within the perturbative scenario the colour transmutation
appears only in order $\alpha_s^2$ and is colour-suppressed. Colour
reconnection at longer time scales is quite feasible, however, and may affect
the fragmentation phase. If so, the nature of non-perturbative QCD can be
probed in a new way. We formulate several alternative toy models and use these
to estimate the colour reconnection probability as a function of the event
kinematics. Possible consequences for LEP~2 events are illustrated, with
special attention to systematic errors in $\W$ mass determinations.


title: CP Violation in Fermion Pair Decays of Neutral Boson Particles

abstract:
  We study CP violation in fermion pair decays of neutral boson particles with
spin 0 or 1. We study a new asymmetry to measure CP violation in $\eta, K_L
\rightarrow \mu^+\mu^-$ decays and discuss the possibility of measuring it
experimentally. For the spin-1 particles case, we study CP violation in the
decays of $J/\psi$ to $SU(3)$ octet baryon pairs. We show that these decays can
be used to put stringent constraints on the electric dipole moments of
$\Lambda$, $\Sigma$ and $\Xi$.


title: Higgs Boson Interference in $\gamma \gamma \rightarrow W^+W^-$

abstract:
  We study interference effects between resonant and nonresonant amplitudes for
the $\gamma \gamma \rightarrow W^+ W^-$ process at a backscattered
photon-photon collider. We show that a Higgs boson with $M_H$ > 200 GeV is
manifest as a resonant dip in the $W^+W^-$ invariant mass spectrum and we
investigate its statistical significance.


title: Squeezed Quantum State of Disoriented Chiral Condensate

abstract:
  We consider the quantum state describing the Disoriented Chiral Condensate
(DCC) which may be produced in high energy collisions. Using the approach
suggested by Rajagopal and Wilczek to describe the amplification of the long
wavelength classical pion modes, we consider the quantum-mechanical evolution
of the initial vacuum state into the final squeezed state describing the DCC.
The obtained wave function has some interesting properties which are discussed.


title:
Determining the Gluon Distributions in the Proton and Photon from
  Two-Jet Production at HERA

abstract:
  Two-jet production from the direct photon contribution at HERA is a sensitive
measure of the small-$x$ gluon in the proton. We propose measurements of ratios
of the jet cross-sections which will clearly distinguish between gluons with or
without singular behaviour at small $x$. Furthermore, we show that analogous
ratio measurements for the resolved photon contribution provide a sensitive way
of determining the gluon distribution in the photon.


title:
From the Deuteron to Deusons, an Analysis of Deuteronlike Meson-Meson
  Bound States

abstract:
  A systematic study of possible deuteronlike two-meson bound states, {\it
deusons}, is presented. Previous arguments that many such bound states may
exist are elaborated with detailed arguments and numerical calculations
including, in particular, the tensor potential. In the heavy meson sector
one-pion exchange alone is strong enough to form at least deuteron-like $B\bar
B^*$ and $B^*\bar B^*$ composites bound by approximately 50 MeV. Composites of
$D\bar D^*$ and $D^*\bar D^*$ states bound by pion exchange alone are expected
near the thresholds, while in the light meson sector one generally needs some
additional short range attraction to form bound states. The quantum numbers of
these states are I=0, In $B\bar B^*$ one predictss the states: $\eta_b(\approx
10545),\ \chi_{b1}(\approx 10562)$, and in $B^*\bar B^*$ one finds the states:
$\eta_b(\approx 10590),\ \chi_{b0}(\approx 10582),\ h_b(\approx 10608),\
\chi_{b2}(\approx 10602)$. Near the $D\bar D^*$ threshold the states:
$\eta_c(\approx 3870),\ \chi_{c0}(\approx 3870)$ are predicted, and near the
$D^*\bar D^*$ threshold one finds the states: $\chi_{b0}(\approx 4015),\
\eta_{c}(\approx 4015),\ h_c(\approx 4015),\ \chi_{c2}(\approx 4015)$. Within
the light meson sector pion exchange gives strong attraction for $P\bar V$ and
$V\bar V$ systems with quantum numbers where the best non-$q\bar q$ candidates
exist, although pion exchange alone is not strong enough to support such bound
states.


title: Unstable particle mixing and CP violation in weak decays

abstract:
  We discuss unstable particle mixing in CP-violating weak decays. It is shown
that for a completely degenerate system unstable particle mixing does not
introduce a CP-violating partial rate difference, and that when the mixings are
small only the off-diagonal mixings are relevant. Also, in the absence of
mixing, unstable particle wave function renormalization does not introduce any
additional effect. An illustrative example is given to heavy scalar decays with
arbitrary mixing.


title: Plasmon Decay: From QED to QCD

abstract:
  Upon using the same theoretical framework, I describe two interesting decay
processes: the electromagnetic plasmon decay into neutrinos, which can be the
dominant cooling mechanism for red giants and white dwarfs, and the gluonic
plasmon decay into quarks, which can be measured in ultra-relativistic
heavy-ion collisions.


title: Strong Decays of $Q \bar Q$ Mesons

abstract:
  We present a detailed study of the two-body strong decays of light mesons.
Both the space part and the spin-flavor-color part of the wave functions are
generated algebraically and closed forms are obtained for all decays.
Experimental deviations from our systematics are seen to be suggestive of both
missing mesons and exotic QCD configurations.


title: QCD Calculation of Heavy Meson Semileptonic Transitions

abstract:
  I review the QCD sum rules calculations of the form factors governing the
semileptonic decays of charmed and beauty mesons. In particular, I discuss the
predicted dependence of the various form factors on $q^2$ and how it can be
obtained for the form factors of vector and axial currents. In some cases the
$q^2$ dependence, computed by QCD sum rules, is different from the outcome of
lattice QCD. A Tau-Charm factory could be an efficient tool to study this
aspect of the charmed meson transitions.


title: Radiative corrections to quark-quark-reggeon vertex in QCD

abstract:
  One loop corrections to the coupling of the reggeized gluon to quarks are
calculated in QCD. Combining this result with the known corrections to the
gluon-gluon-reggeon vertex, we check the self-consistency of the representation
of the amplitudes with gluon quantum numbers and negative signature in the
$t$-channel in terms of Regge pole contribution.


title: Which chiral symmetry is restored in hot QCD?

abstract:
  We review the current status of the problem of chiral symmetry restoration,
discussing an open question of whether at the $SU(N_f)_A$ restoration point
$T=T_c$ the $U(1)_A$ chiral symmetry is or is not (approximately) restored. New
lattice and instanton-based studies are considered, and some new calculations
are suggested to clarify the issue. We also speculate on possible experimental
manifestations of two possible scenarios.


title: Energy Distribution of the Leptons in Top Decay to Charged Higgs

abstract:
  We analyze the energy distribution of the leptons coming from the top decay
$t\ra b\hc,\ bW^+\ra bl^+\nu$. The correlation between the lepton energy
distribution and the top spin may be useful for distinguishing the $\hc$
signature from the $W$ background. Such a correlation can also be useful for
disentangling the two different $\hc \bar tb$ couplings and determining the
experimental value of $\tan\beta$.


title: Electroweak Discussion Section Summary

abstract:
  I summarize our work of electroweak discussion section held at the 14th
International Workshop on Weak Interactions and Neutrinos. We discussed about a
few physics topics related to electroweak interactions, including $B$ and $K$
physics and weak flavor physics.


title:
Some consequences in weak processes of three generations mixing in the
  leptonic sector

abstract:
  We investigate the sensitivity of some weak processes to a
Cabibbo--Kobayashi--Maskawa mixing in the leptonic sector. Values for mixing
angles and masses compatible with several experimental accelerator data were
found. We discuss in this context neutrino oscillations, cosmological and
astrophysical consequences as well.


title:
Diffractive Dissociation and Eikonalization in High Energy pp and p $
  {\bar p} $ Collisions

abstract:
  We show that eikonal corrections imposed on diffraction dissociation
processes calculated in the triple Regge limit, produce a radical change in the
energy dependence of the predicted cross section. The induced correction is
shown to be in general agreement with the new experimental data measured at the
Tevatron.


title: Void Analysis and Hierarchical Structure for Single Jets

abstract:
  After a brief review of the theoretical basis of void scaling function
properties of hierarchical structure, we analyze the phenomenological
consequences at single jet level in Monte Carlo e+e- annihilation events. We
find an interesting alternative approach for characterizing quark and gluon
jets.


title: Factorization in graviton interactions

abstract:
  The study of factorization in the linearized gravity is extended to the
graviton scattering processes with a massive scalar particle, with a massless
vector boson and also with a graviton. Every transition amplitude is shown to
be completely factorized and the physical implications of their common factors
are discussed.


title: Planck Scale Effects and Axions in Supersymmetry

abstract:
  The effects of possible explicit violation of the Peccei-Quinn symmetry
responsible for the solution of the strong CP problem are studied in
supersymmetric models. It is shown that automatic models with an abelian $U(1)$
gauge symmetry are easy to construct both in the context of fundamental and
composite models of axions. It is argued that it is preferable to use abelian
rather than nonabelian gauge groups in order to obtains automatic symmetries. A
composite model with no exact $R$ symmetry is studied and it is found that,
unlike common belief, supersymmetry is broken.


title:
Properties of the BFKL equation and structure function predictions for
  HERA

abstract:
  The general properties of the Lipatov or BFKL equation are reviewed.
Modifications to the infrared region are proposed. Numerical predictions for
the deep-inelastic electron-proton structure functions at small $x$ are
presented and confronted with recent HERA measurements.


title: SO(10) Cosmic Strings and SU(3) Color Cheshire Charge

abstract:
  Certain cosmic strings that occur in GUT models such as $SO(10)$ can carry a
magnetic flux which acts nontrivially on objects carrying $SU(3)_{color}$
quantum numbers. We show that such strings are non-Abelian Alice strings
carrying nonlocalizable colored ``Cheshire" charge. We examine claims made in
the literature that $SO(10)$ strings can have a long-range, topological
Aharonov-Bohm interaction that turns quarks into leptons, and observe that such
a process is impossible. We also discuss flux-flux scattering using a
multi-sheeted formalism.


title:
On the Determination of the $b \rightarrow c$ Handedness Using
  Nonleptonic $\Lambda_c$-Decays

abstract:
  We consider possibilities to determine the handedness of $b \ra c$ current
transitions using semileptonic baryonic $\Lambda_{b} \rightarrow \Lambda_{c}$
transitions. We propose to analyze the longitudinal polarization of the
daughter baryon $\Lambda_c$ by using momentum-spin correlation measurements in
the form of forward-backward (FB) asymmetry measures involving its nonleptonic
decay products. We use an explicit form factor model to determine the
longitudinal polarization of the $\Lambda_c$ in the semileptonic decay
$\Lambda_b \ra \Lambda_c + l^- + \bar \nu_l$. The mean longitudinal
polarization of the $\Lambda_c$ is negative (positive) for left-chiral
(right-chiral) $b \ra c$ current transitions. The frame dependent longitudinal
polarization of the $\Lambda_c$ is large ($\cong 80\%$) in the $\Lambda_b$ rest
frame and somewhat smaller (30\% - 40\%) in the lab frame when the
$\Lambda_b$'s are produced on the $Z_0$ peak. We suggest to use nonleptonic
decay modes of the $\Lambda_c$ to analyze its polarization and thereby to
determine the chirality of the $b \ra c$ transition. Since the $\Lambda_b$'s
produced on the $Z_0$ are expected to be polarized we discuss issues of the
polarization transfer in $\Lambda_b \ra \Lambda_c$ transitions. We also
investigate the $p_\perp$- and $p$-cut sensitivity of our predictions for the
polarization of the $\Lambda_c$.


title: On the Asymptotics of Nielsen-Olesen Vortices

abstract:
  We investigate analytically and numerically the asymptotic behavior of the
Nielsen-Olesen vortex solutions and show that they approach their asymptotic
values exponentially but with exponents that differ from the ones quoted in the
literature. In particular, it is shown that for values of the Higgs
self-coupling that are larger than a critical value, both the Higgs field and
the gauge field approach exponentially their asymptotic values with {\it equal}
exponents that are {\it independent} of the Higgs self-coupling.


title:
Minimal SO(10) Grand Unification: Predictions for Proton Decay and
  Neutrino Masses and Mixings:

abstract:
  Prospects for SO(10) as a minimal grand unification group have recently been
heightened by several considerations such as the MSW resolution of the solar
neutrino puzzle, baryogenesis, possibility for understanding fermion masses
etc. I review the present status of the minimal SO(10) models with special
emphasis on the predictions for proton lifetime and predictions for neutrino
masses for the non-supersymmetric case and discuss some preliminary results for
the supersymmetric case. It was generally believed that minimal SO(10) models
predict wrong mass relations between the charged fermions of the first and
second generations; furthermore, while the smallness of the neutrino masses in
these models arises from the see-saw mechanism, it used to be thought that
detailed predictions for neutrino masses and mixings require further adhoc
assumptions. In this talk, I report some recent work with K.S.Babu, where we
discovered that the minimal SO(10) model, both with and without SUSY, has in it
a built-in mechanism that not only corrects the bad mass relations between the
charged fermions but at the same time allows a complete prediction for the
masses and mixings in the neutrino sector. We define our minimal model as the
one that consists of the smallest set of Higgs multiplets that are needed for
gauge symmetry breaking. Our result is based on the hypothesis that the complex
{\bf 10} of Higgs bosons has only a single coupling to the fermions. This
hypothesis is guaranteed in supersymmetric models and in non-SUSY models that
obey a softly broken Peccei-Quinn symmetry.


title: Diquark Corrleations in the nucleon structure function

abstract:
  The nucleon structure functions are studied with a special emphasis on
diquark correlations inside the nucleon. Assuming a phenomenological
diquark-quark model of the nucleon at the low energy hadronic scale, we
calculate the leading twist contributions to the nucleon structure functions.
We take the Nambu and Jona-Lasinio model for the calculation of the quark
distributions in the diquarks, and use the convolution method for the diquark
scattering process. The resulting quark distributions are evolved to the
experimental momentum scale using the perturbative QCD. We discuss the flavor
dependence of the nucleon structure functions and the importance of the
quark-quark correlations for the understanding of the nucleon structure.


title:
The Effective Potential of Electroweak Theory with Two Massless Higgs
  Doublets at Finite Temperature

abstract:
  The effective potential of electroweak theory with two massless Higgs
doublets at finite temperature is studied. We investigate phase structure and
critical temperature in this model by numerical analysis without
high-temperature expansion. The phase transition is found to be of first order.
The critical temperature is shown to be relatively low for typical scalar
masses. The free energy of the critical bubble is calculated with some
approximations and we find that the bubble nucleation can occur at a
temperature a little below the critical temperature. We also discuss the
possibility of the electroweak baryogenesis.


title:
Cosmological Baryon Asymmetry in Supersymmetric Standard Models and
  Heavy Particle Effects

abstract:
  Cosmological baryon asymmetry B is studied in supersymmetric standard models,
assuming the electroweak reprocessing of B and L. Only when the soft
supersymmetry breaking is taken into account, B is proportional to the
primordial B-L in the supersymmetric standard models. The ratio $B/(B-L)$ is
found to be about one percent less than the nonsupersymmetric case. Even if the
primordial B-L vanishes, scalar-leptons can be more efficient than leptons to
generate B provided that mixing angles $\th$ among scalar leptons satisfy
$|\th| < 10^{-8} (T/{GeV})^{1/2}$.


title:
Comment on ``Neutrino masses and mixing angles in a predictive theory of
  fermion masses''

abstract:
  In the extension of the Dimopoulos--Hall--Raby model of the fermion mass
matrices to the neutrino sector, there is an entry in the up-quark and neutrino
Dirac mass matrices which can be assumed to arise from the Yukawa coupling of a
{\bf 120}, instead of a {\bf 10} or a {\bf 126}, of SO(10). Although this
assumption leads to an extra undetermined complex parameter in the model, the
resulting lepton mixing matrix exhibits the remarkable feature that the $
\nu_{\tau} $ does not mix with the other two neutrinos. Making a reasonable
assumption about the extra parameter, we are able to fit the large-mixing-angle
MSW solution of the solar-neutrino problem, and we obtain $ m_{\nu_{\tau}} \sim
10 $ eV, the right mass range to close the Universe. Other possibilities for
explaining the solar-neutrino deficit are also discussed.


title:
Pseudoscalar Mass Effects in Decays of Taus with Three Pseudoscalar
  Mesons

abstract:
  We study the effects of non-vanishing pseudoscalar masses in $\tau$ decays
into three mesons. The hadronic matrix elements are obtained by using the
generalized structure of the chiral currents with nonvanishing pseudoscalar
masses and implementing the low-lying resonances in the different channels. We
demonstrate that suitable angular distributions are sensitive to the mass
effects in the chiral Langrangian. Numerical results for the rele\-% vant
structure functions are given for the decay modes $\tau\rightarrow
\nu\pi^-\pi^-\pi^+$, $\nu K^-\pi^-\pi^+$ and $\nu K^-\pi^-K^+$.


title: Hyperon-Nucleon Interaction in a Quark Model

abstract:
  A lecture given at the International School Seminar on {\sl Hadrons and
Nuclei from QCD}, Tsuruga-Vladivostok-Sapporo, August-September, 1993.
  A realistic hyperon ($Y$)-nucleon ($N$) interaction based on the quark model
and the one-boson-exchange potential is constructed. The Nijmegen potential
model D with the SU(3) flavor symmetry is modified with a quark exchange
interaction at the short-distance, which replaces the short-range repulsive
core in the original model. The flavor-spin dependences of the short-range
repulsion are qualitatively different from the original hard-core potential. We
also study a two-body weak decay, $\Lambda N \to NN$, in the quark model. An
effective weak interaction, where one-loop QCD corrections are explicitly taken
into account, is employed. Differences from the conventional meson-exchange
processes are discussed.


title: Spin Structure Functions

abstract:
  We review the theory and phenomenology of deep inelastic polarized
lepton-nucleon scattering in the light of recent data with a deuteron target
from the SMC at CERN and a Helium 3 target from the E142 experiment at SLAC.
After including higher-order perturbative QCD corrections, mass corrections and
updated estimates of higher-twist effects, we find good agreement with the
basic Bjorken sum rule, and extract a consistent set of values for the quark
contributions to the proton spin: $$\Delta\Sigma \equiv \Delta u + \Delta d +
\Delta s = 0.27 \pm 0.11 $$ $$\Delta u = 0.82 \pm 0.04, \Delta d = -0.44 \pm
0.04,\Delta s = -0.11 \pm 0.04 $$ which are consistent with chiral soliton
models and indications from lattice estimates. We also mention the prospects
for future experiments on the spin structure of the nucleon.


title: Effects of $e^- e^+ \nu_e$ Decays of Tau Neutrinos Near A Supernova

abstract:
  We revisit the constraints implied by SN 1987 A observations on the decay
rate of a multi-MeV $\nu_\tau$ decaying into the visible channel $\nu_\tau
\rightarrow e^+ e^- \nu_e$, if its lifetime is more than 10 {\it sec.}. We
discuss its implication for the minimal left-right symmetric model with see-saw
mechanism for neutrino masses. We also speculate on the possible formation of a
``giant Capacitor" in intergalactic space due to the decay of "neutronization"
$\nu_\tau$'s and spin allignment possibility in the supernova.


title:
Spontaneous CP Violation and Natural Flavor Conservation In the
  $SU(2)_{L}\times U(1)_{Y}$ Gauge Theory with Two Higgs Doublets

abstract:
  The two principles of spontaneous CP violation and natural flavor
conservation can be realized in the $SU(2)_{L}\times U(1)_{Y}$ model with two
Higgs doublets. In particular, this model provides a consistent application to
the CP violating parameters $\epsilon$ and $\epsilon'/\epsilon$ in kaon decay
and the neutron electric dipole moment. The masses of the exotic scalars are
unconstrained in this model and probing these exotic scalars must be valuable
at the present energy scales. Large CP violations may also occur in the heavy
quark and lepton sectors.


title: A W--dressed Electroweak String

abstract:
  We give plausibility arguments for the existence of a $W$--dressed
electroweak string for the \ws ~model with $\th_W = 0$. This string is a
$Z$--string which in the core has a finite energy contribution from
$W$--condensation induced by the anomalous magnetic moment in the \ym field.
The solution which has minimum energy at $r=0$ interpolates between the
unbroken $(r=0)$ and the broken $(r \ra \infty) \ SU(2) \times U_y(1)$ phase.


title: Does the W Mass Reconstruction Survive QCD Effects?

abstract:
  In the hadronic decay mode of a pair of W bosons, $\text{e}~+\text{e}~- \to
\text{W}~+ \text{W}~- \to \text{q}_1 \overline{\text{q}}_2 \text{q}_3
\overline{\text{q}}_4$, QCD interference effects can mix up the two colour
singlets $\text{q}_1 \overline{\text{q}}_2$ and $\text{q}_3
\overline{\text{q}}_4$, i.e. produce hadrons that cannot be uniquely assigned
to either of W$~+$ and W$~-$. We show that interference is negligible for
energetic perturbative gluon emission, and develop models to help us to
estimate the non-perturbative effects. The total contribution to the systematic
error on the W mass reconstruction may be as large as 40 MeV.


title: Discovering Supersymmetry with Electron and Photon Beams

abstract:
  Linear collider designs are optimized for \ep\ collisions. However, from the
physics point of view, \lc s may also be advantageously operated in an \ee,
\eg\ or \pp\ mode. These options, which have not been available up to now, will
provide unique tests of the \sm\ and of physics beyond it. As an example, we
review the prospects for discovering and studying \susy\ at linear colliders in
\ee, \eg\ and \pp\ collisions. In particular, we argue that \ee\ scattering is
much better suited than \ep\ annihilation for discovering \sel s or \co s.


title: Effective Lagrangian with vector mesons : Linear response theory

abstract:
  The soliton breathing mode is investigated in the framework of linear
response theory within a Skyrme model vector meson stabilized. The effective
Lagrangian considered includes the $\rho$ (introduced following the standard
prescription of nonlinear chiral symmetry) and the $\omega$ mesons. The
monopole response function is found to have a pronounced peak which is
identified to the $P11$ (Roper) resonance. The results are compared to those
obtained within the local approximation.


title: Color Exchange in Near-forward Hard Elastic Ecattering

abstract:
  We study the large-$t$ small angle behavior of quark-quark elastic
scattering. We employ a factorization procedure previously developed for fixed
angle scattering, which depends on the color structure of the factorized hard
subprocess. We find an evolution in $t$ that (in leading logarithmic
approximation) becomes diagonal in a singlet-octet basis in the $t$-channel as
$s\rightarrow \infty$. Octet exhange in the hard scattering is associated with
the familiar `reggeized', $s^{\alpha_g(t)}$ behavior, which arises from
$s$-dependence in Sudakov suppression. In contrast, Sudakov suppression for
$t$-channel singlet exchange in the hard scattering is $s$-independent. In
general, these contributions are mixed by soft corrections, which, however,
cancel in many experimental amplitudes and cross sections.


title: The Tau Neutrino as the Lightest Supersymmetric Particle

abstract:
  Given the conservation of baryon number as well as electron and muon numbers,
all present data can be explained without the need of a conserved quantum
number for the tau lepton and its neutrino. A supersymmetric extension of the
standard model naturally allows for such a scenario. One consequence is that
the tau neutrino becomes the lightest supersymmetric particle.


title:
QCD Corrections to Higgs Boson Production: Non- Leading Terms in the
  Heavy Quark Limit

abstract:
  We compute analytic results for the QCD corrections to Higgs boson production
via gluon fusion in hadronic collisions in the limit in which the top quark is
much heavier than the Higgs boson. The first non-leading corrections of
$\O(\alpha_s^3 \mh^2/m_t^2)$ are given and numerical results presented for both
LHC and SSC energies. We confirm earlier numerical results showing that the
dominant corrections have the same mass dependence as the Born cross section.


title: Poking at the Correspondence Principle with Derivative Couplings

abstract:
  It is shown that quantum mechanical systems obtained from a heuristic path
integral quantization of lagrangians of the form $ L= \sum_{n} \frac{1}{n!}
f_n(q) \dot{q}^n $ violate in general the correspondence principle, unless $L$
is not more than quadratic in $\dot{q}$. The field theoretic counterpart of
this result and its consequence on models of interacting scalar and vector
fields and particularly the electroweak interactions, are briefly discussed.


title: The Greening of Quantum Field Theory: George and I

abstract: This is a lecture given July 14, 1993, at Nottingham.


title: Influence of the Landau-Pomeranchuk Effect on Lepton-Pair Production

abstract:
  An estimate is made of the Landau-Pomeranchuk effect on the production of
dileptons in a hadronic gas and in a quark-gluon plasma. For low mass dilepton
pairs this effect reduces the production rate for bremsstrahlung by an order of
magnitude. For high invariant masses its influence is negligible. This
behaviour is of importance for the theoretical analysis of low mass dilepton
pairs produced in relativistic heavy ion collisions.


title: Weak Annihilation and the Endpoint Spectrum in Semileptonic B Decays

abstract:
  A general relationship is formulated between the contributions of `Weak
Annihilation' (WA) to inclusive semileptonic decays of heavy flavour hadrons
and the matrix elements of four fermion operators. We argue that
nonperturbative contributions from low energy hadronic final states provide the
dominant impact of WA on the semileptonic $b\ra u$ width of $B^-$ mesons. In
that case WA affects the lepton spectrum mainly in its endpoint region -- i.e.
beyond the kinematical boundary for $b\ra c$ transitions -- and we expect
thelater to look quite different in $B^-$ than in $B_d$ decays. At present we
are unable to make a truly quantitative prediction; yet a detailled
experimental comparison of the $B^-$ and the $B_d$ lepton spectra will enable
one to determine the size of the relevant matrix elements and to check directly
to what extent the factorization approximation works here. Using universal
analyticity properties of the decay amplitude we analyze WA in the perturbative
regime and rederive our earlier results about the absence of a power
enhancement due to gluon emission in a more general way. We address also the
problem of the invariant mass of hadrons in the final state in semileptonic $B$
decays and identify nontrivial cancellations in $\aver{M^2\ind{hadr}}$.


title: The Decay Rate Asymmetry of the Top Quark

abstract:
  The asymmetries ${\cal A}_k \equiv [\Gamma(\twddec) -\Gamma(\tbwddec)]
/[\Gamma(\twddec) + \Gamma(\tbwddec)]$ in the partial widths of the top quark
decays are discussed within the Standard Model (SM), the Two-Higgs-Doublet
Model (2HDM) and supersymmetric extensions of the SM (SSM). The leading
contributions to these asymmetries in the SM and in the 2HDM are induced by the
up-type quark self-energy diagrams and are found to be very small. However, in
the SSM, the asymmetry ${\cal A}_b$ can be substantial, ${\cal
O}(\alpha_{QCD})$, provided the CP-violating phase of gluino-top-stop couplings
is not suppressed. Within the SSM ${\cal A}_b$ is generated by the vertex
corrections.


title: Signatures for Hybrids

abstract:
  In this review talk I summarize theoretical expectations for properties of
hybrid mesons and baryons, and discuss the prospects for identifying these
states experimentally. This is an expanded version of an Invited Contribution
to the Conference on Exclusive Reactions at High Momentum Transfers, Marciana
Marina, Elba, Italy, 24-26 June 1993.


title:
Astrophysical Bounds on Milli-Charged Particles in Models with a
  Paraphoton

abstract:
  The upper bound on the number of relativistic species present at
nucleosynthesis has been used to constrain particles with electric charge
$\epsilon e$ ($10^{-8} < \epsilon <1$). We correct the bound previously
calculated for milli-charged particles that interact with a shadow photon. We
also discuss the additional constraints from the properties of red giants and
of Supernova 1987A.


title: The Search for a Light `Intermediate Mass' Higgs Boson

abstract:
  We review recent progress in techniques for searching for the Standard Model
light `Intermediate Mass' Higgs Boson ($80 \GeV \lsim M_H \lsim 140\GeV$). We
pay particular attention to associated production at the SSC and LHC where we
search for the Higgs produced in association with either a $W$ boson or a $t$
quark. This production mode can be detected cleanly when the Higgs decays into
two isolated photons, and the associated heavy particle decays
semi-leptonically. We discuss the possibility that radiative corrections may
significantly enhance the $W \gamma\gamma$ background, decreasing the
significance of the $WH$ signal. Based upon a Plenary talk given at the SSC
Symposium, Madison, March 1993.


title: Detecting Technibaryon Dark Matter

abstract:
  The technibaryon constitutes a possible dark matter candidate. Such a
particle with electroweak quantum numbers is already nearly ruled out as the
dominant component of the galactic dark matter by nuclear recoil experiments.
Here, the scattering of singlet technibaryons, without electroweak quantum
numbers, is considered. For scalar technibaryons the most important interaction
is the charge radius. The scattering rates are typically of order $10^{-4}$ (kg
keV day)$^{-1}$ for a technicolor scale of 1 TeV. For fermionic technibaryons
the most important interaction is the magnetic dipole moment. The scattering
rates in this case are considerably larger, typically between $10^{-1}$ and 1
(kg keV day)$^{-1}$, depending on the detector material. Rates this large may
be detectable in the next generation of nuclear recoil experiments. Such
experiments will also be sensitive to quite small technibaryon electric dipole
moments.


title:
Like Sign Dilepton Signature for Gluino Production at LHC with or
  without R Conservation

abstract:
  The isolated like sign dilepton signature for gluino production is
investigated at the LHC energy for the $R$ conserving as well as the $L$ and
$B$ violating SUSY models over a wide range of the parameter space. One gets
viable signals for gluino masses of 300 and 600 GeV for both $R$ conserving and
$L$ violating models, while it is less promising for the $B$ violating case.
For a 1000 GeV gluino, the $L$ violating signal should still be viable; but the
$R$ conserving signal becomes too small at least for the low luminosity option
of LHC.


title: Precision Data Parameters and Grand Unification Predictions

abstract:
  When realizing the Minimal Supersymmetric Standard Model (MSSM) within a
(simple) Grand Unified Theory (GUT), the predicted ranges for the strong
coupling and the ratio of two Higgs doublet expectation values are strongly
correlated with the weak angle and the $t$-quark mass. (The latter are
extracted from precision data.) We spell out those relations and point out the
implication for the mass of the light MSSM (CP even) Higgs boson.


title: The Proton Spin Structure in Skyrme Type Models

abstract:
  It is demonstrated how in the soliton approach to baryons a small but
non-vanishing matrix element of the axial singlet current is obtained.
Furthermore it is shown that these models also provide a mechanism to
disentangle the ``matter" and ``glue" contributions to this matrix element.
Numerical results indeed exhibit a cancellation between these two components.
However, the magnitudes of both turn out to be significantly smaller than
unity.


title: B Decays in the Standard Model and Beyond

abstract:
  B decays in and beyond the standard model are reviewed. I specifically
discuss right-handed B decays, rare B decays, B_c decays, B_s-B_s(bar) mixing,
and T violation. (Plenary talk given at the `Workshop on B Physics at Hadron
Accelerators', Snowmass, Colorado, June 21-July 2, 1993.)


title: Signatures of left-right symmetry at high energies

abstract:
  We discuss various experimental tests of the left-right symmetric model
possible to perform in the next generation linear colliders. We consider
processes which provide sensitive probes of the basic ingredients of the model:
right-handed gauge bosons, right-handed Majorana neutrinos, lepton number
violating interactions and triplet Higgs scalars. A supersymmetric version of
the left-right model is also studied and some distinctive experimental tests
for it is proposed. One of the main messages of this talk is to emphasize the
usefulness of the collision modes $e^-e^-$, $e^-\gamma$ and $\gamma\gamma$ for
the tests of the left-right symmetric model.


title: Chemical Relaxation Times in a Hadron Gas at Finite Temperature

abstract:
  The relaxation times of particle numbers in hot hadronic matter with
vanishing baryon number are estimated using the ideal gas approximation and
taking into account resonance decays and annihilation processes as the only
sources of particle number fluctuations. Near the QCD critical temperature the
longest relaxation times turn out to be of the order of 10 fm and grow roughly
exponentially to become of the order of $10^{3}$ fm at temperatures around 100
MeV. As a consequence of such long relaxation times, a clear departure from
chemical equilibrium must be observed in the momentum distribution of secondary
particles produced in high energy nuclear collisions.


title: Leptogenesis in Supersymmetric Standard Model with Right-handed Neutrino

abstract:
  We show that the leptogenesis is automatic within the supersymmetric standard
model if there exist right-handed neutrinos with mass less than $H_{\it inf}$,
the expansion rate during the inflation. Its scalar component grows during the
inflation due to the quantum fluctuation, oscillates coherently after the
inflation, and its decay generates lepton asymmetry. The scenario is naturally
embedded into $SO(10)$ GUT without any modifications. We also discuss the case
with heavier right-handed neutrino.


title:
A Consistent Next-to-Leading-Order QCD Calculation of Hadronic
  Diffractive Scattering

abstract:
  We calculate the order alpha_s^2 and order alpha_s^3 QCD contributions to
colour-singlet exchange in the leading log s approximation. We implement the
resulting amplitude at the hadronic level and thus construct the QCD pomeron
and odderon to this order of perturbation theory. We show that the structure of
the hadronic form factors provides a natural mechanism through which the
odderon gets suppressed at t=0 whereas it dominates the elastic cross section
at large t. We also demonstrate that the inclusion of nonperturbative effects
through a modification of the gluon propagator accelerates greatly the
convergence of the log s expansion, although not enough to provide agreement
with the data.


title: Light Quark Masses from Exclusive Tau Decays: An Experimental Proposal

abstract:
  A method of indirect measurement of the light quark running mass $\hat{m} =
(m_d + m_u)/2$ is elaborated in detail. It is based on measuring 1\%-level
azimuthal angular asymmetries in the decay $\tau \rightarrow \nu_\tau + 3\pi$.
The latter are then used in QCD sum rules to obtain experimental lower bounds
for $\hat{m}$. For a sample of $2.5 \times 10^5$ $\tau \rightarrow \nu_\tau +
3\pi$ decays free of background, the resulting statistical error in the bound
for $\hat{m}$ is estimated to be 1 MeV, i.e., comparable to the systematic
error due to the use of QCD sum rules. Contribution to the Third Workshop on
the $\tau$ Charm Factory 1-6 June 1993, Marbella, Spain.


title: Cheshire Cat Hadrons

abstract:
  This article is based on a series of lectures given at ELAF 93 on the
description of low-energy hadronic systems {\it in and out} of hadronic medium.
The focus is put on identifying, with the help of a Cheshire Cat philosophy,
the effective degrees of freedom relevant for the strong interactions from a
certain number of generic symmetry properties of QCD. The matters treated are
the ground-state and excited-state properties of light- and heavy-quark baryons
and applications to nuclei and nuclear matter under normal as well as extreme
conditions.


title: Dimensional Reduction in Non-Supersymmetric Theories

abstract:
  It is shown that regularisation by dimensional reduction is a viable
alternative to dimensional regularisation in non-supersymmetric theories.


title:
One-loop Effective Lagrangian for a Standard Model with a Heavy Charged
  Scalar Singlet

abstract:
  We study several problems related to the construction and the use of
effective Lagrangians by considering an extension of the standard model that
includes a heavy scalar singlet coupled to the leptonic doublet. Starting from
the full renormalizable model, we build an effective field theory by
integrating out the heavy scalar. A local effective Lagrangian (up to operators
of dimension six) is obtained by expanding the one-loop effective action in
inverse powers of the heavy mass. This is done by matching some Green functions
calculated with both the full and the effective theories.
  Using this simple example we study the renormalization of effective
Lagrangians in general and discuss how they can be used to bound new physics.
We also discuss the effective Lagrangian after spontaneous symmetry breaking,
and the use of the standard model classical equations of motion to rewrite it
in different forms. The final effective Lagrangian in the physical basis is
well suited to the study of the phenomenology of the model, which we comment on
briefly. Finally, as an example of the use of our effective field theory, we
consider the leptonic flavour-changing decay of the $Z$ boson in the effective
theory and compare the results obtained with the full model calculation.


title:
The Non-Trivial Phase of $\phi ^{4}$-Theory in an External Magnetic
  Field and at Finite Temperature

abstract:
  The effective potential for the order parameter $\phi ^{\dagger } \phi$ is
investigated in massless $\phi ^{4}$-theory in the presence of magnetic fields
at finite temperature. It is found that the first order nature of the phase
transition from the non-trivial to the perturbative ground state at a critical
temperature is unchanged by the presence of magnetic fields, though they do
increase the critical temperature and weaken the barrier separating the
perturbative from the non-trivial phase. The results might be relevant for the
electro-weak phase transition as well as for inflationary models of the early
universe.


title: Axion Emission from Red Giants and White Dwarfs

abstract:
  Using thermal field theory methods, we recalculate axion emission from dense
plasmas. We study in particular the Primakoff and the bremsstrahlung processes.
The Primakoff rate is significantly suppressed at high densities, when the
electrons become relativistic. However, the bound on the axion-photon coupling,
$G<10^{-10}$ GeV, is unaffected, as it is constrained by the evolution of HB
stars, which have low densities. In contradistinction, the same relativistic
effects enhance the bremsstrahlung processes. From the red giants and white
dwarfs evolution, we obtain a conservative bound on the axion-electron
coupling, $g_{ae} < 2\times 10^{-13}$.


title: Long-Lived Charged Heavy Leptons

abstract:
  Very little is known about the mass spectrum of fermions in the standard
model. In this talk, I point out that in the simplest extension of the standard
model, in which all right-handed fields are singlets, it is quite possible that
a fourth-generation neutrino will be heavier that its charged counterpart. The
latter will then be very long-lived. Three plausible values of the mixing angle
give very different phenomenology; the charged lepton will either decay at the
vertex (albeit into a massless neutrino), away from the vertex but within the
detector, or will pass completely through the detector. In the latter case,
then if the detectors at the LHC and SSC have the ability to determine the
velocity of these particles, they will look just like muons and be missed. In
the extreme case in which the mixing angle is only generated by Planck scale
effects (it can't be zero for cosmological reasons), not only is detection
possible, but collection for further study may be possible. Finally, in an
alternative model in which the fourth generation leptons form an isodoublet,
the possible decay of the charged lepton into $\tau Z$ offers a promising,
nearly background free, method of detection.


title: The Spin Structure of the Nucleon

abstract:
  We provide an introduction to the ideas of spin-dependent deep-inelastic
scattering. Recent experimental results are summarised and possible
explanations related to the axial anomaly presented. Further experiments that
could greatly clarify the situation are also described.


title: General Determination of Phases in Quark Mass Matrices

abstract:
  We construct new invariants and give several theorems which determine in
general (i) the number of physically meaningful phases in quark mass matrices
and (ii) which elements of these matrices can be rendered real by rephasings.
We illustrate our results with simple models.


title:
Progress in Evaluating Some Complicated Types of Feynman Diagrams with
  Two (and More) Loops

abstract:
  Problems occurring in physically important non-trivial examples of loop
calculations are discussed.
  A procedure of deriving expansions of two-loop self-energy diagrams with
different masses is constructed. The cases of small and large external momentum
are considered. The coefficients of the expansions are calculated analytically.
Comparison with numerical results shows good agreement below the first
threshold and above the last threshold of the diagram.
  An approach to evaluating three- and four-point ladder diagrams with massless
internal particles and off-shell external momenta is presented. Exact results
for an arbitrary number of loops are obtained. Evaluating non-planar diagrams
is also discussed.


title:
Hyperons in the Bound State Approach to the Nambu--Jona-Lasinio Chiral
  Soliton

abstract:
  For the Nambu--Jona--Lasinio (NJL) model in the proper time regularization
scheme the chiral soliton is investigated for the case of three flavors within
the framework of the bound state approach to strangeness. For this purpose
meson fluctuations off the non--strange soliton are considered. For the kaon
P--wave channel the emerging Bethe--Salpeter equation is solved yielding the
bound state energy and wave--function. This kaon bound state also induces a
strange valence quark wave--function. Collective coordinates are introduced for
the SU(2) isorotations and the coupling of the bound state to these rotations
is determined. The total spin is decomposed into parts carried by the soliton
and the bound state. The absolute value of the former is identical to the total
isospin while the latter is demonstrated to be identical to the expectation
value of the grand spin, the sum of spin and isospin. The functional trace
involves quark states with various grand spins which get polarized by the kaon
bound state. This polarization results in a normalization of the coupling
between the collective rotation and the bound state different from the Skyrme
model. Nevertheless after quantization the expression for the baryon masses can
be cast into the form found by Callan and Klebanov for the Skyrme model.
Numerical results for the baryon spectrum are compared to those obtained in the
same model using the collective approach of Yabu and Ando. It is found that for
$\frac{1}{2}^+$ baryons the bound state treatment reproduces the experimental
data better than the collective approach while there are only small differences
between the two approaches for the $\frac{3}{2}^+$ baryons. Both treatments
underestimate the mass splittings for baryons with different strangeness. This
short-coming is conjectured to be inherited from the meson sector of the NJL
model where too small a ratio of the kaon and pion decay constants is
predicted.


title:
Effects of Possible $\Delta B =- \Delta Q$ Transitions in Neutral $B$
  Meson Decays}

abstract:
  We explore the possibility that the existing data on like-sign dileptons at
the $\Upsilon (4S)$ resonance consist of events arising from $B_{d}^0 -\bar
B_{d}^0$ mixing and also from $\Delta B = - \Delta Q$ transitions. The
consequences of these nonstandard transitions for certain time-asymmetries
which are likely to be measured at the $B$ factories are studied.


title:
Enhancement of the $K_L$ -- $K_S$ Mass Difference by Short Distance QCD
  Corrections Beyond Leading Logarithms

abstract:
  We calculate the next-to-leading order short distance QCD corrections to the
coefficient $\eta_1$ of the effective $\Delta S = 2$ hamiltonian in the
standard model. This part dominates the short distance contribution $(\Delta
m_K)^{\rm SD}$ to the $K_L$ -- $K_S$ mass difference. The next-to-leading order
result enhances $\eta_1$ and $(\Delta m_K)^{\rm SD}$ by 20\% compared to the
leading order estimate. Taking $0.200 \gev \le \laMSb \le 0.350 \gev$ and $1.35
\gev \le m_c(m_c) \le 1.45 \gev$ we obtain $0.922 \le \eta_1^{\rm NLO} \le
1.419$ compared to $0.834 \le \eta_1^{\rm LO} \le 1.138$. For $B_K = 0.7$ this
corresponds to 48 -- 75 \% of the experimentally observed mass difference. The
inclusion of next-to- leading order corrections to $\eta_1$ reduces
considerably the theoretical uncertainty related to the choice of
renormalization scales.


title:
Weak dipole moment of $\tau$ in $e^+e^-$ collisions with longitudinally
  polarized electrons

abstract:
  It is pointed out that certain CP-odd momentum correlations in the production
and subsequent decay of tau pairs in $e^+e^-$ collisions get enhanced when the
$e^-$ is longitudinally polarized. Analytic expressions for these correlations
are obtained for the single-pion decay mode of $\tau$ when $\tau^+\tau^-$ have
a ``weak" dipole form factor (WDFF) coupling to $Z$ . For $e^+e^-$ collisions
at the $Z$ peak, a sensitivity of about 1-5$\times 10^{-17}$\mbox{$e$ cm} for
the $\tau$ WDFF can be reached using a {\em single} $\tau^+\tau^-$ decay
channel, with $10^6\, Z$'s likely to be available at the SLC at Stanford with
$e^-$ polarization of 62\%-75\%.


title: Principal Value Resummation

abstract:
  We present a new resummation formula for the Drell-Yan cross section. The
formal resummation of threshold corrections in Drell-Yan hard-scattering
functions produces an exponent with singularities from the infrared pole of the
QCD running coupling. Our reformulation treats such `infrared renormalons' by a
principal value prescription, analogous to a modified Borel transform. The
resulting expression includes all large threshold corrections to the hard
scattering function as an asymptotic series in $\alpha_s$, but is a finite
function of $Q^2$. We find that the ambiguities of the resummed perturbation
theory imply the presence of higher twist corrections to quark-antiquark
hard-scattering functions that begin at $\Lambda_{QCD}/Q$. This suggests an
important role for higher twist in the phenomonolgy of hadron-hadron inclusive
cross sections. We also discuss the numerical evaluation of the exponent and
its asymptotic perturbation series for representative values of $Q^2$.


title: Sterile Neutrinos and Future Solar Neutrino Experiments

abstract:
  It is shown that future solar neutrino experiments (SNO, Super-Kamiokande and
others), in which high energy neutrinos will be detected (mostly from 8B
decay), may allow to answer in a model independent way the question whether
there are transitions of solar $\nu_e$'s into sterile states. No assumptions
about the initial flux of 8B neutrinos are done. Lower bounds for the
probability of transition of solar $\nu_e$'s into all possible sterile states
are derived and expressed through measurable quantities.


title: The Theory Of Ideal Yang-Mills Fluids In Symmetric Hyperbolic Form

abstract:
  The theory of ideal Yang-Mills fluids (IYMF; a Yang-Mills field coupled to a
fluid in the limit of infinite conductivity) is embedded in symmetric
hyperbolic form. This yields both causality and well-posedness of initial value
problems in this theory. The embedding is based on a covariant, constraint-free
divergence formulation of IYMF, developped by the author previously for
magneto-hydrodynamics. Expressions for the small amplitude wave structure are
also derived, showing that in general Alfven waves do not persist in the
presence of colored magnetic fields.


title:
ERRATUM TO: Power corrections $1/Q^2$ to parton sum rules for deep
  inelastic scattering from polarized targets

abstract:
  We clarify conflicting results in the literature on coefficient functions in
front of higher twist operators contributing to the parton sum rules for deep
inelastic scattering from polarized targets. The necessary corrections do not
affect our calculations of matrix elements, published in
Phys.Lett.B242(1990)245, but change final estimates of the $\sim 1/Q^2$
contributions to Bjorken and Ellis--Jaffe sum rules.


title: A Symmetry Approach to CP Violation

abstract:
  One of the greatest challenges for particle physics in the 1990's is
understanding the broken symmetry of CP violation. It is now almost 30 years
since the discovery in 1964 of the $K_{L} \rightarrow 2\pi$ decay. What has
happened since? Why has there been no significant new experimental input in
this long period? The original $K_{L} \rightarrow 2\pi$ decay experiment is
described by two parameters $\epsilon$ and $\epsilon'$. Today $\epsilon \approx
$ its 1964 value while $\epsilon'$ still consistent with zero, and there is no
new evidence for CP violation outside the kaon system. Why is it so hard to
find CP violation? How can B Physics Help? We present a symmetry approach to
these questions.


title: Ideas on charm and beauty decays

abstract:
  The parton model, a zero-order approximation in many treatments, is shown to
be a ``semiclassical" model whose results for certain averages also hold
(correspondence principle) in quantum mechanics. Algebraic techniques developed
for the M\"ossbauer effect exploit simple features of commutators to obtain sum
rules showing the validity of the parton model for $b \rightarrow c$
semileptonic decays in the classical limit, $\hbar \rightarrow 0$, where all
commutators vanish, and in general, even when binding effects are included, for
the lowest moments of the lepton energy spectrum at fixed 3-momentum transfer.
Interference between the $u \bar u$ and $d \bar d$ components of the $\rho^o$
and $\omega$ wave functions can be used as clues to contributions from small
weak amplitudes and CP violation in decays to final states including these
vector mesons.


title: Non-Equilibrium Evolution of Scalar Fields in FRW Cosmologies I

abstract:
  We derive the effective equations for the out of equilibrium time evolution
of the order parameter and the fluctuations of a scalar field theory in
spatially flat FRW cosmologies.The calculation is performed both to one-loop
and in a non-perturbative, self-consistent Hartree approximation.The method
consists of evolving an initial functional thermal density matrix in time and
is suitable for studying phase transitions out of equilibrium. The
renormalization aspects are studied in detail and we find that the counterterms
depend on the initial state. We investigate the high temperature expansion and
show that it breaks down at long times. We also obtain the time evolution of
the initial Boltzmann distribution functions, and argue that to one-loop order
or in the Hartree approximation, the time evolved state is a ``squeezed''
state. We illustrate the departure from thermal equilibrium by numerically
studying the case of a free massive scalar field in de Sitter and radiation
dominated cosmologies. It is found that a suitably defined non-equilibrium
entropy per mode increases linearly with comoving time in a de Sitter
cosmology, whereas it is {\it not} a monotonically increasing function in the
radiation dominated case.


title: Mass Matrix Models: The Sequel

abstract:
  The smallness of the quark sector parameters and the hierarchy between them
could be the result of a horizontal symmetry broken by a small parameter. Such
an explicitly broken symmetry can arise from an exact symmetry which is
spontaneously broken. Constraints on the scales of new physics arise {}from new
flavor changing interactions and {}from Landau poles, but do not exclude the
possibility of observable signatures at the TeV scale. Such a horizontal
symmetry could also lead to many interesting results: (i) quark -- squark
alignment that would suppress, without squark degeneracy, flavor changing
neutral currents induced by supersymmetric particles, (ii) exact relations
between mass ratios and mixing angles, (iii) a solution of the $\mu$-problem
and (iv) a natural mechanism for obtaining hierarchy among various symmetry
breaking scales.


title:
Shadowing in deuterium and the small--$x$ limit of $F_2^n/F_2^p$ and
  $F_2^p - F_2^n$

abstract:
  We discuss the updated NMC determination of $F_2^n/F_2^p$ and $F_2^p -
F_2^n$. Shadowing effects in deuterium make the structure functions determined
by the NMC sensibly different from the true ones in the low--$x$ region. We
show that the departure of $F_2^n/F_2^p$ and $F_2^p-F_2^n$ from the Regge
expectations at small $x$ observed by the NMC likely disappears if one takes
into account the shadowing corrections.


title: $\Pi$ in the Sky ? Microwave Anisotropies from Cosmic Defects

abstract:
  High resolution maps of the anisotropy of the microwave sky will yield
invaluable clues as to the mechanisms involved in cosmic structure formation.
One fundamental question they should answer is whether the fluctuations were
Gaussian random noise, as predicted in inflationary models, or were nonGaussian
as in theories based on symmetry breaking and cosmic defects. In the latter
case there is the prospect of obtaining information regarding symmetry breaking
at high energy scales, specifically the homotopy classes $\Pi_n$ of the vacuum
manifold. In this paper we report on detailed calculations of the degree scale
anisotropies predicted in the cosmic string, monopole texture and
nontopological texture theories of structure formation, emphasising their
distinct character from those predicted by inflation, and the bright prospects
for experimental tests.


title:
Proposals for measuring transversity distributions in deep inelastic
  electron scattering and a model for E-704 asymmetries

abstract:
  We present the principles of the measurement of the quark transversity
distributions in semi-inclusive deep inelastic electron scattering, which form
the basis of HELP and one of the ELFE proposals. A string model for
Collins-type asymmetry in polarized quark fragmentation function is proposed. A
possible role of the Collins effect in the single spin asymmetries observed by
experiment E 704 at Fermilab is suggested.


title:
K_S\rightarrow \gamma\gamma , K_L\rightarrow\pi^0\gamma\gamma$ and
  Unitarity

abstract:
  Agreement between the experimental value $\Gamma (K_S\rightarrow
\gamma\gamma)$ and the number predicted via a one-loop chiral perturbation
theory calculation has been cited as a success for the latter. On the other
hand the one-loop prediction for the closely related process $K_L\rightarrow
\pi^0\gamma\gamma$ has been found to be a factor three below the experimental
value. Using the inputs of unitarity and dispersion relations, we demonstrate
the importance of higher order loop effects to both of these processes.


title: Near Future Perpectives of QCD Spin Studies

abstract:
  We consider the physics motivations and perspectives for the study of spin
phenomena at the future high energies accelerators. The possibilities to use
the already operating machines are also discussed. It is emphasized that the
present status of QCD spin studies necessarily requires a wide range of spin
measurements


title:
Penguin contributions to rates and CP asymmetries in non-leptonic
  B-decays. Possible experimental procedures and estimates

abstract:
  We present a study of non-leptonic B-meson decays, partial widths and CP
asymmetries, and discuss the possibilities of determining the penguin
contributions through less model-dependent phenomenological analyses. In the
last section we employ a specific model to give more definite numerical
predictions.


title: Light Gluinos at LEP

abstract:
  We study the production and decay of \lgl s in \ep\ collisions. We suggest a
signature which suffers little from backgrounds and argue that the \lgl\ window
can already be closed with the existing LEP data, provided the gluino lifetime
is such that it decays within the detectors.


title: Parton Interaction Rates and Limits on Perturbative QCD

abstract:
  The relevance of parton interaction rates for observables of a quark- gluon
plasma and for testing field theoretical methods is exhibited. Using the
Braaten-Pisarski method the interaction rate as well as the transport rate
beyond the leading logarithm approximation are estimated. Limts on the validity
of perturbative QCD for relativistic heavy ion collisions are discussed.


title: Threshold Pion Electroproduction in Chiral Perturbation Theory

abstract:
  Electroproduction of pions on the nucleon near the threshold is analyzed
within the framework of baryon chiral perturbation theory. We give a thorough
discussion of the low--energy theorems related to charged and neutral
electropionproduction. It is shown how the axial radius of the nucleon can be
related to the S--wave multipoles $E_{0+}^{(-)}$ and $L_{0+}^{(-)}$. The chiral
perturbation theory calculations of the $\gamma^\star p \to \pi^0 p$ reaction
are found to be in good agreement with the recent near threshold data. We also
discuss the influence of some isospin--breaking effects in this channel. For
future experimental tests of the underlying chiral dynamics, extensive
predictions of differential cross sections and multipole amplitudes are
presented.


title:
Spontaneous symmetry breaking of (1+1)-dimensional $\phi^4$ theory in
  light-front field theory (II)

abstract:
  We discuss spontaneous symmetry breaking of (1+1)-dimensional $\phi^4$ theory
in light-front field theory using a Tamm-Dancoff truncation. We show that, even
though light-front field theory has a simple vacuum state which is an
eigenstate of the full Hamiltonian, the field can develop a nonzero vacuum
expectation value. This occurs because the zero mode of the field must satisfy
an operator valued constraint equation. In the context of (1+1)-dimensional
$\phi^4$ theory we present solutions to the constraint equation using a
Tamm-Dancoff truncation to a finite number of particles and modes. We study the
behavior of the zero mode as a function of coupling and Fock space truncation.
The zero mode introduces new interactions into the Hamiltonian which breaks the
$Z_2$ symmetry of the theory when the coupling is stronger than the critical
coupling.


title: Fritzsch Texture in SUSY-SO(10) with Large Neutrino Mixing

abstract:
  Fritzsch's texture is imposed on {\em all} mass matrices in a SUSY-SO(10) via
a family $U(1)_{PQ}$ symmetry. The observed charged fermion parameters fix the
$\nu$-masses and mixing, while the later are evolved from the GUT scale to low
energies using the RG. Large $\sin^2 2{\theta}_{12}$ results. As in a SUSY-GUT
no intermediate scale is allowed, the RH-neutrino scale is the unification one
and this gives in our model $\Delta m_{12}^2 \approx {10}^{-10} eV^2$, in
accordance with the vacuum oscillation solution to the solar-$\nu$ puzzle.


title:
$b \to s \gamma$ Decay in $SU(2)_L \times SU(2)_R \times U(1)$
  Extensions of the Standard Model

abstract:
  The rare radiative decay $b \to s \gamma$ is studied in $SU(2)_L \times
SU(2)_R \times U(1)$ extensions of the Standard Model. Matching conditions for
coefficients of operators appearing in the low energy effective Hamiltonian for
this process are derived, and QCD corrections to these coefficients are
analyzed. The $b \to s \gamma$ decay rate is then calculated and compared with
the corresponding Standard Model result. We find that observable deviations
from Standard Model predictions can occur in $SU(2)_L \times SU(2)_R \times
U(1)$ theories for a reasonable range of parameter values.


title: Progress in SSC Physics: Report of the Higgs Working Group

abstract:
  I review new developments in Higgs physics and electroweak symmetry breaking
that have resulted from the Madison--Argonne workshops on SSC physics.


title: Non Leptonic Two Body Decays of B Mesons

abstract:
  Within the framework of the factorization approximation, two body
non-leptonic decays of $B$ mesons are related to semileptonic matrix elements
and form factors, evaluated with an effective lagrangian incorporating both
chiral and heavy quark symmetries. Using semileptonic $D$-decay data, estimates
for nonleptonic processes are obtained.


title: Natural Slow-Roll Inflation

abstract:
  It is shown that the non-perturbative dynamics of a phase change to the
non-trivial phase of $\lambda\varphi^4$-theory in the early universe can give
rise to slow-rollover inflation without recourse to unnaturally small
couplings.


title: On the Wess-Zumino-Witten anomalous functional at finite temperature

abstract:
  We discuss the finite temperature extension of the anomalous Wess-Zumino
-Witten lagrangian. The finite temperature S^1\times S^3 compactification makes
a structure in disconnected sectors, corresponding to different baryon numbers
appear naturally. The consistency of the anomalous functional is proved for
arbitrary baryon number configurations. The anomalous behavior of the
functional is shown to be consistent with the absence of finite temperature
corrections to chiral anomalies in
  QCD, for each baryon number sector.


title: A Bound on $m_\eta/m_{\eta'}$ for Large $N_C$

abstract:
  If the number of colors is large, the ratio $m_\eta/m_{\eta'}$ is bounded
from above. The bound is not satisfied by the observed $\eta$ and $\eta'$
masses.


title:
The Non-Trivial Effective Potential of the `Trivial' lambda Phi^4
  Theory: A Lattice Test

abstract:
  The strong evidence for the `triviality' of (lambda Phi^4)_4 theory is not
incompatible with spontaneous symmetry breaking. Indeed, for a `trivial' theory
the effective potential should be given exactly by the classical potential plus
the free-field zero-point energy of the shifted field; i.e., by the one-loop
effective potential. When this is renormalized in a simple, but nonperturbative
way, one finds, self-consistently, that the shifted field does become
non-interacting in the continuum limit. For a classically scale-invariant (CSI)
lambda Phi^4 theory one finds m_h^2 = 8 pi^2 v^2, predicting a 2.2 TeV Higgs
boson. Here we extend our earlier work in three ways: (i) we discuss the
analogy with the hard-sphere Bose gas; (ii) we extend the analysis from the CSI
case to the general case; and (iii) we propose a test of the predicted shape of
the effective potential that could be tested in a lattice simulation.


title: A New Time Contour for Thermal Field Theories

abstract:
  A new time contour is used to derive real-time thermal field theory. Unlike
previous path integral approaches, no contributions to the generating
functional are dropped.


title:
Possibility of Studying Electroweak Symmetry Breaking at \gamma \gamma
  Colliders

abstract:
  The studies of the electroweak symmetry breaking sector (EWSBS) at
$\gamma\gamma$ colliders were considered previously in the loop processes of
$\gamma\gamma \to w_Lw_L,\,z_Lz_L$, but they are suffered from the huge $W_T
W_T$ and $Z_TZ_T$ backgrounds. Here we present another possible process that
involves spectator $W$'s and $W_L$'s, the latter of which are scattered
strongly by the interactions of the EWSBS. We also show that this process
should be safe from the transverse backgrounds and it can probe the structure
of the EWSBS.


title: Transverse Momentum Distributions for Heavy Quark Pairs

abstract:
  We study the transverse momentum distribution for a $pair$ of heavy quarks
produced in hadron-hadron interactions. Predictions for the large transverse
momentum region are based on exact order $\alpha_s^3$ QCD perturbation theory.
For the small transverse momentum region, we use techniques for all orders
resummation of leading logarithmic contributions associated with initial state
soft gluon radiation. The combination provides the transverse momentum
distribution of heavy quark pairs for all transverse momenta. Explicit results
are presented for $b\bar b$ pair production at the Fermilab Tevatron collider
and for $c\bar c$ pair production at fixed target energies.


abstract:
  Magnetic quadrupole moment of $W$-boson in Kobayashi-Maskawa model, I.B.
Khriplovich and M.E. Pospelov, BUDKERINP 93--88 Due to CP-invariance violation
a vector particle can acquire T- and P-odd electromagnetic moment, magnetic
quadrupole one. The W-boson magnetic quadrupole moment is calculated in the
Kobayashi-Maskawa model. This is the only known CP-odd moment arising in this
model in two-loop approximation.


title: Rydberg Wave Packets are Squeezed States

abstract:
  We point out that Rydberg wave packets (and similar ``coherent" molecular
packets) are, in general, squeezed states, rather than the more elementary
coherent states. This observation allows a more intuitive understanding of
their properties; e.g., their revivals.


title: Perturbative QCD Forbidden Charmonium Decays and Gluonia

abstract:
  We address the problem of observed charmonium decays which should be
forbidden in perturbative QCD. We examine the model in which these decays
proceed through a gluonic component of the $J/\Psi$ and the $\eta_c$, arising
from a mixing of $(c\bar c)$ and glueball states. We give some bounds on the
values of the mixing angles and propose the study of the $p \bar{p} \to \phi
\phi$ reaction, at $\sqrt{s} \simeq 3$ GeV, as an independent test of the
model.


title: Hadron Production Ratios as Probes of Confinement and Freeze-Out

abstract:
  Particle production in central S-A collisions at 200 GeV/A energy is analysed
within a thermal model. Present data imply that the strange particles freeze
out at a higher temperature than the non-strange particles and that the
strangeness saturation is incomplete.


title: Aspects of Heavy Quark Production in Polarized Proton-Proton Collisions

abstract:
  We examine the spin-dependence of b-quark production at large transverse
momentum in polarized proton-proton collisions. The leading-order (LO) 2 -> 2
subprocesses, g + g -> Q + Q-bar and q+ q-bar -> Q + Q-bar have a large
`analyzing power', as measured by the average spin-spin asymmetry <a-hat_{LL}>,
at large p_T, approaching -100%. The contributions from next-to-leading order
(NLO) 2 -> 3 processes are also discussed and found to be dominated at large
transverse momentum by subprocesses with a large and positive partonic level
spin asymmetry leading to strong cancellations with the LO predictions. The
results suggest that b-quark production might constitute an interesting test of
the spin-dependence of NLO QCD but they also point up the importance of a full
calculation of the complete O(\alpha_S^3) spin-dependent corrections for a
successful extraction of the polarized gluon distribution. Similarities to
gluino pair production are also briefly discussed.


title: Finite-Element Quantum Electrodynamics

abstract:
  We apply the finite-element lattice equations of motion for quantum
electrodynamics to an examination of anomalies in the current operators. By
taking explicit lattice divergences of the vector and axial-vector currents we
compute the vector and axial-vector anomalies in two and four dimensions. We
examine anomalous commutators of the currents to compute divergent and finite
Schwinger terms. And, using free lattice propagators, we compute the vacuum
polarization in two dimensions and hence the anomaly in the Schwinger model.
(To appear in the Proceedings of the International Europhysics Conference on
High Energy Physics, Marseille, July 22-28, 1993.)


title: Supersymmetric top decays

abstract:
  The supersymmetric decays of the top quark into charged Higgs plus bottom,
$\thb$, and into the supersymmetric partner of the top (${\wti u}_1$) plus the
lightest neutralino (${\wti \chi}_1^0$), $\tstopneu$, are discussed within the
framework of the Minimal Supersymmetric Standard Model with radiatively induced
breaking of the gauge group $SU(2)\times U(1)$. The possibility of detecting
these decays at present, i.e. given the available bounds on supersymmetric
parameters, is compared with the situation a Next $e^+e^-$ Linear Collider
would face if supersymmetric particles were still undiscovered at LEP~II. The
indirect implications for $\thb$ and $\tstopneu$ of a measurement of the bottom
quark decay $\bsgamma$ at the Standard Model level are taken into account. }}


title: Closing the Windows on Mev Tau Neutrinos

abstract:
  In this note, we analyze various constraints on the ``visible'' decay modes
of a massive $\tau $ neutrino, $\nu_\tau\rightarrow\nu^\prime\,\gamma $ and
$\nu_\tau\rightarrow\nu^\prime\, e^+ e^-$, where $\nu^\prime$ is a light
neutrino. The BEBC beam dump experiment provides model-independent constraints
on these modes. The lifetime for the $\nu^\prime\, e^+e^-$ mode is constrained
to be $\tau_{\nu^\prime\, e^+e^-} \ge 0.18~(m_{\nu_\tau}/MeV)~sec.$ We point
out that the same experiment implies a similar constraint on the
$\nu^\prime\,\gamma$ mode. This results in a new upper limit on the transition
magnetic moment of $\nu_\tau$, $\mu_{\rm tran} \le 1.1 \times 10^{-9}
(MeV/m_{\nu_\tau})^2 \mu_B $. Furthermore, a limit on the electric charge of
$\nu_\tau$ may be obtained, $Q_{\nu_\tau} \le 4 \times 10^{-4}e$. Combining
these constraints with those arising from supernova observations and primordial
nucleosynthesis calculations, we show that these ``visible'' decays cannot be
the dominant decay modes of the $\tau$ neutrino.


title:
Improving the Weizs\"acker-Williams Approximation in Electron-Proton
  Collisions

abstract:
  We critically examine the validity of the Weizs\"acker-Williams approximation
in electron-hadron collisions. We show that in its commonly used form it can
lead to large errors, and we show how to improve it in order to get accurate
results. In particular, we present an improved form that is valid beyond the
leading logarithmic approximation in the case when a small-angle cut is applied
to the scattered electron. Furthermore we include comparisons of the
approximate expressions with the exact electroproduction calculation in the
case of heavy-quark production.


title:
Measuring the Gluon Helicity Difference Distribution Function of the
  Proton using Photoproduction Processes

abstract:
  Little information is known about the polarization of gluons inside a
longitudinally polarized proton. I report on the sensitivity of photoproduction
experiments to it. Both jet and heavy quark production are considered.


title: Neutrino Mixing and Future Solar Neutrino Experiments

abstract:
  Possibilities of a model independent treatment of the data from future
real-time solar neutrino experiments (SNO, Super-Kamiokande and others) are
discussed. It is shown that in the general case of transitions of the initial
solar $\nu_e$'s into $\nu_\mu$ and/or $\nu_\tau$ the total flux of initial 8B
neutrinos and the $\nu_e$ survival probability can be determined directly from
the experimental data. Lower bounds for the probability of transition of solar
$\nu_e$'s into all possible sterile states are derived and expressed through
measurable quantities.


title: The reactions \gwl\ and \gzl\ in $SU(N)$ strongly interacting theories

abstract:
  Building on recent phenomenology of \gpi, we discuss the expectation for two
photon production of longitudinal gauge boson pairs in $SU(N)$ technicolor
theories. The treatment involves a matching of dispersive techniques with the
methodology of chiral perturbation theory.


title: Collective Fields for QCD

abstract:
  A gauge-symmetric approach to effective Lagrangians is described with special
emphasis on derivations of effective low-energy Lagrangians from QCD. The
examples we discuss are based on exact rewritings of cut-off QCD in terms of
new collective degrees of freedom. These cut-off Lagrangians are thus
``effective'' in the sense that they explicitly contain some of the physical
long-distance degrees of freedom from the outset.(Talk presented by P.H.
Damgaard at the workshop on ``Quantum Field Theoretical Methods in High Energy
Physics'', Kyffhauser, Germany, Sept. 1993. To appear in those proceedings).


title: Anomalies, VMD and the Enjl Model

abstract:
  We show how the effective action of the Extended Nambu--Jona-Lasinio model
(ENJL) can be defined in the presence of anomalies in a way that reproduces the
flavour anomaly. This necessarily breaks Vector Meson Dominance (VMD) in the
usual sense. The same method can be used to construct other chiral effective
theories involving constituent quarks and spin-1 mesons that give the correct
flavour anomaly. We also comment on how standard VMD is the root of this
problem and those observed by previous authors in implementing VMD in the
anomalous sector.


title: The Determination of $|\Vcb|$ and QCD Sum Rules in Hqet

abstract:
  I review recent developments in Heavy Quark Effective Theory (HQET) that lead
to an almost model--independent determination of the $|\Vcb|$ element of the
Cabibbo--Kobayashi--Maskawa matrix from exclusive semileptonic $B\ra D^{(*)}$
decays. In particular, I compare the theoretical uncertainties in the $B\ra
D^*\ell\,\bar\nu$ and the $B\ra D\,\ell\,\bar\nu$ decay modes. I discuss the
applications of QCD sum rules within HQET to semileptonic heavy meson decays
and give predictions for the form factors measurable in $B\ra
D^{(*)}\ell\,\bar\nu$ decays.


title: Deep Inelastic Scattering Beyond Perturbation Theory

abstract:
  I discuss possibilities to observe the instanton-induced contributions to
deep inelastic scattering which correspond to nonperturbative exponential
corrections to the coefficient functions in front of parton distributions of
the leading twist.


title: Reduction of general two-loop self-energies to standard scalar integrals

abstract:
  We present a method for reducing general two-loop self-energies to standard
scalar integrals in massive gauge theories with special emphasis on the
electroweak Standard Model. It includes the tensor integral reduction for all
two-loop integrals appearing in self-energy calculations. The results are valid
for arbitrary values of the invariant momentum $p^2$, all particle masses, the
space-time dimension $D$ and the gauge parameters $\xi _i \; (i = \gamma , Z,
W)$. The algebraic structure of the results clearly displays the gauge
dependence of the considered quantities and allows to perform very stringent
checks. We explicitly verify Slavnov-Taylor identities by calculating several
thousand Feynman-diagrams and adding them up algebraically. As an application
we calculate the light fermion contributions to the two-loop gauge boson
self-energies of the electroweak SM. We study their gauge dependence and
discuss the occurring standard integrals.


title:
$\chi_{c2} \to \rho\rho$ Decay and the $\rho$ Polarization in Inclusive
  Processes: A Test of Mass Effects

abstract:
  We compute the helicity density matrix of $\rho$ vector mesons produced in
the two-body decays of $\chi_{c2}$'s in the framework of perturbative QCD,
allowing for mass corrections. The $\chi_{c2}$'s are inclusively produced in
hadronic interactions via gluon fusion and are shown to be strongly polarized.
Both the case in which the light quarks inside the final mesons are treated as
massless current quarks and the case in which they are seen as constituent
massive ones are considered. Our results show significant differences between
the two cases; the measurement of the $\rho$ helicity density matrix should
allow a test of the importance of these mass effects.


title: Recent Developments in the Theory of Heavy Quarks

abstract:
  Recent developments in the theory of heavy quarks are reviewed. In the area
of heavy quark fragmentation, there has been progress in the study of both
pertubative and nonperturbative processes, including the identification of new
observable nonperturbative fragmentation parameters. There has also been
considerable theoretical activity in the study of inclusive rare and
semileptonic decays of bottom hadrons.


title: Vector Leptoquark Production at Hadron Colliders

abstract:
  We explore the production of vector leptoquarks ($V$) at the Tevatron, LHC,
and SSC through both quark-antiquark and gluon fusion: $q \bar q, gg \to VV$.
The cross sections are found to be somewhat larger than for scalar leptoquarks
of the same mass implying enhanced search capabilities. Contributed to the
Workshop on Physics at Current Accelerators and the Supercollider, Argonne
National Lab, June 1993.


title: Light-Quark, Heavy-Quark Systems: An Update

abstract:
  We review many of the recently developed applications of Heavy Quark
Effective Theory techniques. After a brief update on Luke's theorem, we
describe striking relations between heavy baryon form factors, and how to use
them to estimate the accuracy of the extraction of $|V_{cb}|$. We discuss
factorization and compare with experiment. An elementary presentation, with
sample applications, of reparametrization invariance comes next. The final and
most extensive chapter in this review deals with phenomenological lagrangians
that incorporate heavy-quark spin-flavor as well as light quark chiral
symmetries. We compile many interesting results and discuss the validity of the
calculations.


title: Constraints on Three-Neutrino Mixing from Atmospheric and Reactor Data

abstract:
  Observations of atmospheric neutrinos are usually analyzed using the
simplifying approximation that either \(\nu_\mu \leftrightarrow \nu_\tau\) or
\(\nu_e \leftrightarrow \nu_\mu\) two-flavor mixing is relevant. Here we
instead consider the data using the simplifying approximation that only one
neutrino mass scale is relevant. This approximation is the minimal three-flavor
notation that includes the two relevant two-flavor approximations. The
constraints in the parameter space orthogonal to the usual, two-flavor analyses
are studied.


title: Nonperturbative Matching for Field Theories with Heavy Fermions

abstract:
  We examine a paradox, suggested by Banks and Dabholkar, concerning
nonperturbative effects in an effective field theory which is obtained by
integrating out a generation of heavy fermions, where the heavy fermion masses
arise from Yukawa couplings. They argue that light fermions in the effective
theory appear to decay via instanton processes, whereas their decay is
forbidden in the full theory. We resolve this paradox by showing that such
processes in fact do not occur in the effective theory, due to matching
corrections which cause the relevant light field configurations to have
infinite action.