title:
Electroweak Precision Measurements and the Minimal Supersymmetric
  Standard Model

abstract:
  We discuss supersymmetric contributions to the electroweak precision
measurements in the Minimal Supersymmetric Standard Model for two cases: the
quark-lepton universality violation $\delta_{q\ell}$ in charged currents and
the ratio $R_b=\Gamma(Z\rightarrow b\bar{b})/\Gamma(Z\rightarrow \rm hadrons)$.
The recent experimental data suggest deviations from the Standard Model for
these observables, at the 1-$\sigma$ level for the former and at more than
3-$\sigma$ level for the latter. We analyze the non-oblique corrections from
the SUSY particles to explain these discrepancies. The observed non-zero
$\delta_{q\ell}$ may be explained by relatively light sleptons, charginos and
neutralinos. Although the observed excess of $R_b$ can be explained by very
light scalar top and chargino for low $\tan\beta$, this interpretation is
severely constrained by the opening of exotic decay modes for the top quark.


title:
Algebraic Content of Chiral Symmetry and the Strong Transitions of Heavy
  Mesons

abstract:
  The algebraic content of chiral symmetry constrains the strong interactions
of mesons containing a single heavy quark. We show that the S-wave single-pion
transition amplitudes of all heavy meson states are determined as a consequence
of the participation of these states in reducible multiplets of unbroken
$SU(2)_L\times SU(2)_R$. We find this representation content by making use of
phenomenologically inspired Lie-algebraic sum rules, together with QCD
constraints on the heavy meson spectrum in the heavy quark limit. For example,
the transition amplitude for the process $P^*\rightarrow P\pi$, where $P$ is a
$D$ or a $B$ meson, is predicted to vanish. We also consider the Kaon system in
light of our general conclusions for $I=\oneh$ states.


title:
Updated: Higgs Mass Bounds Separate Models of Electroweak Symmetry
  Breaking

abstract:
  Vacuum stability and metastability imply lower limits on the mass of the
higgs boson in the Standard Model (SM). In contrast, we present an improved
calculation of an upper limit on the lightest higgs mass in supersymmetric
(susy) models, by summing to all orders in perturbation theory the leading and
next--to--leading logarithms with a renormalization group equation technique,
and by including finite two-loop QCD corrections.The improvement lowers the
Minimal Susy Standard Model (MSSM) upper limit by about 10 GeV. The main
uncertainty in each limit is the value of the top mass, which is now
constrained by the Fermilab results. We study the possibility that these bounds
do not overlap, and find that (i) a mass gap emerges between the SM and the
MSSM at $m_t\sim 175$ GeV for $\alpha_s(M_Z^2)=0.118$ and at $m_t \sim 180$ GeV
for more generous values $\sim (0.130)$ of $\alpha_s$; and between the SM and
the Minimal plus Singlet Susy Model [(M+1)SSM] if the independent scalar
self--coupling of the latter is perturbatively small or if the $\tan\beta$
parameter is large; these gaps widen with increasing $m_t$; (ii) the mass gap
emerges with $m_t$ 10 GeV lighter if only vacuum stability and not
metastability is imposed; (iii) there is no overlap between the SM and the MSSM
bounds at even smaller values of $m_t$ for the $\tan\beta$ value ($\sim 1$--2)
preferred in Supersymmetric Grand Unified Theories. Thus, a measurement of the
first higgs mass will serve to exclude either the MSSM/(M+1)SSM higgs sectors
or the SM higgs sector. Finally, we comment on the discovery potential for the
lightest higgses in these models.


title:
Searching for Invisible and Almost Invisible Particles at e^+e^-
  Colliders

abstract:
  We explore the techniques, cross sections and expected signal significance
for detecting invisible and almost invisible particles at LEP2 and the NLC by
means of a hard photon tag. Examples from supersymmetry include the lightest
chargino and second lightest neutralino when their masses are nearly the same
as that of the lightest neutralino (the LSP), and invisibly decaying
sneutrinos. The importance of particular features of the detectors is
discussed, instrumentation for vetoing a fast e^+ or e^- in the beam hole being
especially crucial.


title: Strong and Electromagnetic Interactions of Heavy Baryons

abstract:
  It is possible to express all the strong and electromagnetic interactions of
ground state hadrons in terms of a single coupling constant and the constituent
quark masses, using spin-flavour relativistic supermultiplet theory. Results
are generally accurate to within 10%.


title: Tests of the Standard Model

abstract:
  In this conference report a summary is given on the recent theoretical work
that has contributed to improve the theoretical predictions for testing the
standard model in present and future experiments. Precision calculations for
the $Z$ resonance are reviewed and the status of the standard model is
discussed in the light of the recent top discovery and of the results from
precision experiments. Furthermore, theoretical progress for the Higgs search,
for $W$ physics at LEP II, and for the anomalous magnetic moment of the muon is
summarized. New Physics beyond the minimal model is briefly discussed, in
particular the mimimal supersymmetric standard model in view of the recent
electroweak precision data.


title: The Pion-Nucleon Sigma Term and the Goldberger-Treiman Discrepancy

abstract:
  The pion-nucleon sigma term is shown to be equal to the Goldberger-Treiman
discrepancy at tree level. Its value estimated this way is very sensitive to
the pion-nucleon coupling constant g_{pi NN}. This relation, when combined with
the pion-nucleon S-wave scattering lengths, yields a new determination of g_{pi
NN} at tree level. The results of a one-loop analysis are also summarized
determining an allowed range for the induced pseudoscalar coupling constant
g_P.


title: Chiral symmetry and the reaction $\gamma p \to \pi^0 p$

abstract:
  We analyze the new threshold data for neutral pion photoproduction off
protons in the framework of heavy baryon chiral perturbation theory. We show
that large loop corrections are needed to understand the S--wave multipole
$E_{0+}$ and that all pertinent low--energy constants can be understood within
the framework of resonance exchange saturation. Previous inconsistencies in the
description of this reaction in the threshold region are resolved.


title: Some Aspects of Spin Physics at RHIC

abstract:
  We discuss some of the issues to be accounted under conducting spin physics
program at RHIC.


title: Intermittency for coherent and incoherent current ensemble model

abstract:
  We investigate the origin of intermittency for multiparticle distribution in
momentum space, following the idea that there is a kind of power law
distribution of the space-time region of hadron emission. Using the formalism
of current ensamble model to describe boson sources we discuss intermittency
exponents for the coherent and incoherent ( chaotic) particle production
scheme.


title:
On the SUSY Accompanied Neutrino Exchange Mechanism of Neutrinoless
  Double Beta Decay

abstract:
  The neutrinoless double beta decay ($\znbb$) induced by light Majorana
neutrino exchange between decaying nucleons, accompanied by the squark exchange
inside one nucleon, recently discussed by Babu and Mohapatra, is carefully
analyzed both from the particle and nuclear physics sides. New nuclear matrix
elements relevant to this mechanism are calculated. We extend the analysis to
include mixing of light neutrinos with heavy and "sterile" neutrinos. It
introduces another supersymmetric (SUSY) contribution to $\znbb$. We discuss
constraints on the \rp MSSM parameters imposed by the current experimental
limit on $\znbb$ decay half-life of $^{76}$Ge.


title: Some aspects of transversity

abstract:
  The specificities of transverse polarization with respect to helicity of
ultrarelativistic fermions are pointed out. For massless fermions, a covariant
transversity four-vector is defined, up to a kind of gauge transformation. The
tranversity distribution of quarks in a nucleon is defined. Its possible
connection to the magnetic or electric dipole moment of the baryon is
conjectured. Consequences of the approximate chiral invariance on transverse
spin asymmetries in hard processes are enumerated. The "sheared jet effect"
introduced by Collins for measuring the transverse polarization of a final
quark is presented.


title: $R_b$ -- $R_c$ Crisis and New Physics

abstract:
  The experimental values of $R_b$ and $R_c$ are the only data which do not
seem to agree with Standard Model predictions. Although it is still premature
to draw any definite conclusions, it is timely to look for new physics which
could explain the excess in $R_b$ and deficit in $R_c$. We investigate this
problem in a simple extension of the Standard Model, where a charge $+2/3$
isosinglet quark is added to the standard spectrum. Upon the further
introduction of an extra scalar doublet, one finds a solution with interesting
consequences.


title: Photon Contribution to the ``Super-hard" Pomeron

abstract:
  It is shown that direct photons provide a leading twist mechanism for
diffractive jet production in which the jets carry away all of the momentum
lost by the proton. Two-photon processes are thus expected to asymptotically
dominate "super-hard" pomeron events in $ep$ collisions. We report the expected
rates from these events for the recent ZEUS and H1 data cuts. We also estimate
the direct photon contribution to the "super-hard" pomeron events observed by
the CERN UA8 group for $p\bar p$ collisions.


title: Inflation at Low Scales: General Analysis and a Detailed Model

abstract:
  Models of inflationary cosmology based on spontaneous symmetry breaking
typically suffer from the shortcoming that the symmetry breaking scale is
driven to nearly the Planck scale by observational constraints. In this paper
we investigate inflationary potentials in a general context, and show that this
difficulty is characteristic only of potentials $V(\phi)$ dominated near their
maxima by terms of order $\phi^2$. We find that potentials dominated by terms
of order $\phi^m$ with \hbox{$m > 2$} can satisfy observational constraints at
an arbitrary symmetry breaking scale. Of particular interest, the spectral
index of density fluctuations is shown to depend only on the order of the
lowest non-vanishing derivative of $V(\phi)$ near the maximum. This result is
illustrated in the context of a specific model, with a broken ${\rm SO(3)}$
symmetry, in which the potential is generated by gauge boson loops.


title: Sum Rules for Radiative and Strong Decays of Heavy Mesons

abstract:
  We derive two model-independent sum rules relating the transition matrix
elements for radiative and strong decays of excited heavy mesons to properties
of the lowest-lying heavy mesons. The sum rule for the radiative decays is an
analog of the Cabibbo-Radicati sum rule and expresses the sum of the radiative
widths in terms of the isovector charge radius of the ground state heavy meson.
Using model-dependent estimates and heavy hadron chiral perturbation theory
calculations, we show that this sum rule is close to saturation with states of
excitation energies less than 1 GeV. An analog of the Adler-Weisberger sum rule
gives an useful sum rule for the pionic widths of heavy excited mesons, which
is used to set a model-independent upper bound on the coupling of the P-wave
heavy mesons.


title:
Self Consistent $1/N_c$ Expansion In The Presence Of Electroweak
  Interactions

abstract:
  In the conventional approach to the $1/N_c$ expansion, electroweak
interactions are switched off and large $N_c$ QCD is treated in isolation. We
study the self-consistency of taking the large $N_c$ limit in the presence of
electroweak interaction. If the electroweak coupling constants are held
constant, the large $N_c$ counting rules are violated by processes involving
internal photon or weak boson lines. Anomaly cancellations, however, fix the
ratio of electric charges of different fermions. This allows a self-consistent
way to scale down the electronic charge $e$ in the large $N_c$ limit and hence
restoring the validity of the large $N_c$ counting rules.


title: Nuclear dependence of Q^2 evolution in the structure function F_2

abstract:
  $Q^2$ evolution of the structure functions $F_2$ in tin and carbon nuclei is
investigated in order to understand recent NMC measurements. $F_2$ is evolved
by using leading-order DGLAP, next-to-leading-order DGLAP, and
parton-recombination equations. NMC experimental result $\partial
[F_2^{Sn}/F_2^C]/ \partial [\ln Q^2]\ne 0$ could be essentially understood by
the difference of parton distributions in the tin and carbon nuclei. However,
we find an interesting indication that large higher-twist effects on the $Q^2$
evolution could be ruled out. Nuclear dependence of the $Q^2$ evolution could
be interesting for further detailed studies. 1. Introduction 2. Q^2 evolution
of F_2 in tin and carbon nuclei 3. Conclusions


title: Axionic Extensions of the Standard Model

abstract:
  After a brief review of the axion solution of the strong CP problem, its
supersymmetric extension and the superstring axion are discussed. I also
present one interesting cosmological scenario, the axino-gravitino cosmology,
for the large scale structure of the universe.


title: Large-$p_\perp$ Heavy-Quark Production in Two-Photon Collisions

abstract:
  The next-to-leading-order (NLO) cross section for the production of heavy
quarks at large transverse momenta ($p_\perp$) in $\gamma\gamma$ collisions is
calculated with perturbative fragmentation functions (PFF's). This approach
allows for a resummation of terms $\propto\alpha_s\ln(p_\perp^2/m^2)$ which
arise in NLO from collinear emission of gluons by heavy quarks at large
$p_\perp$ or from almost collinear branching of photons or gluons into
heavy-quark pairs. We present single-inclusive distributions in $p_\perp$ and
rapidity including direct and resolved photons for $\gamma\gamma$ production of
heavy quarks at $e^+e^-$ colliders and at high-energy $\gamma\gamma$ colliders.
The results are compared with the fixed-order calculation for $m$ finite
including QCD radiative corrections. The two approaches differ in the
definitions and relative contributions of the direct and resolved terms, but
essentially agree in their sum. The resummation of the $\alpha_s
\ln(p_\perp^2/m^2)$ terms in the PFF approach leads to a softer $p_\perp$
distribution and to a reduced sensitivity to the choice of the renormalization
and factorization scales.


title: Application of Current Algebra or chiral symmetry to Tau hadronic decays

abstract:
  $\tau\to\pi\pi\nu$, $\tau\to\pi K\nu$, $\tau\to K\eta\nu$, $\tau\to 3\pi\nu$
and $\tau\to \pi\pi K\nu$ have been investigated using chiral symmetry with
dispersion relation in agreement with the unitarity condition.


title: Colorless States in Perturbative QCD: Charmonium and Rapidity Gaps

abstract:
  We point out that an unorthodox way to describe the production of rapidity
gaps in deep inelastic scattering, recently proposed by Buchm\"uller and
Hebecker, suggests a description of the production of heavy quark bound states
which is in agreement with data. The approach questions the conventional
treatment of the color quantum number in perturbative QCD.


title:
Hyperfine Splittings in Heavy Quarkonia From a New Improved Spin
  Dependent Potential

abstract:
  A formula for an improved spin--dependent potential between a heavy quark and
a heavy antiquark was developed using Heavy Quark Effective Theory techniques.
The leading logarithmic quark mass terms emerging from loop contributions were
explicitly extracted and summed up. There is no renormalization scale
dependence in this new formula and it includes both the Eichten--Feinberg
formula as well as the one--loop QCD result as special cases. The hyperfine
splittings were calculated using the spin--spin part of this improved formula.
For charmonium the $J/\psi$-$\eta_c$ $S$-wave splitting agrees well with the
data while the energy difference $\Delta M_P$ between the center of gravity of
the $1^3P_{0,1,2}$ states and the $1^1P_1$ state has the correct sign but is
somewhat larger than the experimental value; however, there are also several
other contributions to $\Delta M_P$ of comparable magnitude ($\sim 1$ MeV),
which we discuss. The corresponding mass differences for the $b\bar{b}$ and
$b\bar{c}$ mesons are also predicted.


title: What We Can Learn About Nucleon Spin Structure From Recent Data

abstract:
  We have used recent polarized deep-inelastic scattering data from CERN and
SLAC to extract information about nucleon spin structure. We find that the SMC
proton data, the E142 neutron data and the deuteron data from SMC and E143 give
different results for fractions of the spin carried by each of the
constituents. These appear to lead to two different and incompatible models for
the polarized strange sea. The polarized gluon distribution occuring in the
gluon anomaly does not have to be large in order to be consistent with either
set of experimental data. However, it appears that the discrepancies in the
implications of these data cannot be resolved with any simple theoretical
arguments. We conclude that more experiments must be performed in order to
adequately determine the fraction of spin carried by each of the nucleon
constituents.


title: The Effects of a Vector-like Doublet as the Fourth Generation to $R_b$

abstract:
  We study the effects of a vector-like SU(2) doublet quarks as the fourth
generation on $R_b$ and $R_c$. By considering the constraint from the
experimental data of forward-backward asymmetry, $A_{FB}^b$ and $A_{FB}^c$,as
well as FCNC among light quarks, we show that there is an allowed region of
parameters for $R_b$ but not for $R_c$.


title: Bremsstrahlung corrections to the decay $b \to s \gamma$

abstract:
  We calculate the O($\alpha_s$) gluon Bremsstrahlung corrections to the
inclusive decay $b \rightarrow s \gamma$, involving the full operator basis
$\hat O_1$ -- $\hat O_8$. Confirming and extending earlier calculations of Ali
and Greub, we give formulas for the total decay width as well as the
perturbative photon spectrum, regarding the former as a necessary part of the
forthcoming complete NLO analysis. We explore in detail the renormalization
scale dependence of our results and find it considerably increased.


title: HQET and Form Factor Effects in $B\to K^{(*)}\ell^+\ell^-$

abstract:
  We examine the rates for the exclusive decays $B\to K^{(*)}\ell^+\ell^-$. We
use the scaling predictions of the heavy quark effective theory to extract the
necessary form factors from fits to various combinations of data. These data
include the $D\to K^{(*)}\ell\nu$ semileptonic decays, as well as the
nonleptonic decays $B\to K^{(*)}\psi^{(\prime)}$ and the rare decay $B\to
K^*\gamma$. We use different parametrizations of form factors, and find that
integrated decay rates are not very sensitive to the forms chosen. However, the
decay spectra and the forward-backward asymmetry in $B\to K^*\ell^+\ell^-$ are
sensitive to the forms chosen for the form factors, while the lepton
polarization asymmetry in $\bar B^0\to \bar K^0\mu^+\mu^-$ is largely
independent of the choice of form factors. Contributions from charmonium
resonances dominate the spectra and integrated rates. In our `best' scenario,
we find $Br(\bar B^0\to \bar K^0\mu^+\mu^-)=2.0\pm 0.3\times 10^{-6}$ and
$Br(\bar B^0\to \bar K^{*0}\mu^+\mu^-)=8.1\pm 2.0\times 10^{-6}$. We also make
predictions for other polarization observables in these decays.


title: CP-Violating Observables in Tagged $D^0$--$\bar{D}^0$ Decays

abstract:
  We perform a systematic study of CP-violating observables in \ddbar\ decays.
We show that given a final state, which may be a CP eigenstate or not, all the
observables can in principle be measured if decay-time information is available
and if, for CP non-eigenstates, both decay rates into $f$ and $\bar f$ are
considered. As an illustration of our analysis we discuss an effective
superweak scenario.


title:
Photon and Z induced heavy charged lepton pair production at a hadron
  supercollider

abstract:
  We investigate the pair production of charged heavy leptons via
photon-induced processes at the proposed CERN Large Hadron Collider (LHC).
Using effective photon and Z approximations, rates are given for $L^+L^-$
production due to $\gamma \gamma$ fusion and $Z \gamma$ fusion for the cases of
inelastic, elastic and semi-elastic $pp$ collisions. These are compared with
the corresponding rates for production via the gluon fusion and Drell-Yan
mechanisms. Various $\gamma \gamma$ and $Z \gamma$ differential luminosities
for $pp$ collisions are also presented.


title: Dynamical P-parity Breaking in Effective Quark Model

abstract:
  Fermion models with selfinteraction including derivatives of fields are
investigated in the strong coupling regime. The existence of three phases is
established in the two channel model near tricritical point. The special phase
of dynamical P-parity breaking is found.


title:
On the Masses of the Physical Mesons: Solving the Effective
  QCD--Hamiltonian by DLCQ

abstract:
  The effective QCD-interaction as obtained from the front form Hamiltonian by
DLCQ is Fourier transformed on the Retarded Schr\"odinger Equation for to
describe the constituents of physical mesons. The crucial point is the use of a
running coupling constant $\alpha_s(Q^2)$, in a manner similar but not equal to
the one of Richardson in the equal usual-time quantization. Fixing the running
coupling constant at the Z mass, the only parameters are the flavor masses.
Without the top quark one needs thus 5 parameters to calculate the physical
masses of 30 pseudoscalar and vector mesons, consistently within the same
model. Applying variational methods to a caricature of the model, the biggest
technical challenge is the solution of a cubic algebraic equation. -- In view
of an oversimplified model and a very simple technology, the agreement with the
empirical data is much too good.


title: Gauge-Yukawa Unification in $SO(10)$ SUSY GUTs

abstract:
  We study supersymmetric unified models with three fermion generations based
on the gauge group $SO(10)$ and require Gauge-Yukawa Unification, i.e., a
renormalization group invariant functional relationship among the gauge and
Yukawa couplings of the third generation in the symmetric phase. In the case of
the minimal model, we find that the predicted values for the top and bottom
quark masses are in agreement with the present experimental data for a wide
range of supersymmetry breaking scales. We also find that an experimental
accuracy of less than $1 \%$ for the top quark mass could test the
corresponding prediction of the Gauge-Yukawa unified model.


title: Determination of the pion-nucleon coupling constant from QCD sum rules

abstract:
  We evaluate the $\pi N$ coupling constant using a QCD sum rule based on the
pion-to-vacuum matrix element of the correlator of two interpolating nucleon
fields. The part of the correlator with Dirac structure $k\llap/\gamma_5$ is
used, keeping all terms up to dimension 5 in the OPE and including continuum
contributions on the phenomenological side. The ratio of this sum rule to the
nucleon sum rule involving condensates of odd dimension yields stable results
with values of $g_{\pi N}$ in the range $12\pm 5$. The sources of uncertainty
are discussed.


title: Precision Measurements at a Muon Collider

abstract:
  We discuss the potential for making precision measurements of $M_W$ and $M_T$
at a muon collider and the motivations for each measurement. A comparison is
made with the precision measurements expected at other facilities. The
measurement of the top quark decay width is also discussed.


title: On the Flavor Dependence of the Mixed Quark-Gluon Condensate

abstract:
  The flavour dependence of the mixed quark-gluon condensate is studied through
the analysis of correlators of the hybrid current $a_{\mu}=g\bar
s\gamma_{\rho}\gamma_5 G_{\rho\mu}d$. The flavour symmetry breaking for this
type of condensates is found to be less than that for the quark condensates.
For the ratio of strange to nonstrange condensates we obtain \mbox{$R=0.95\pm
0.15$}. For the kaon coupling to the current $a_\mu$ we find
$\delta'^2=(0.020\pm0.005)GeV^2$, which is an order of magnitude smaller than
analogous chirally unsuppressed coupling.


title: Nuclear Dependence in Direct Photon Production

abstract:
  We calculate the nuclear dependence of direct photon production in
hadron-nucleus collisions. In terms of a multiple scattering picture, we
factorize the cross section for direct photon production into calculable
short-distance partonic parts times multiparton correlation functions in
nuclei. We present the hadron-nucleus cross section as $A^{\alpha}$ times the
hadron-nucleon cross section. Using information on the multiparton correlation
functions extracted from photon-nucleus experiments, we compute the value of
$\alpha$ as a function of transverse momentum of the direct photon. We also
compare our results with recent data from Fermilab experiment E706.


title:
From Quantum Field Theory to Hydrodynamics: Transport Coefficients and
  Effective Kinetic Theory

abstract:
  The evaluation of hydrodynamic transport coefficients in relativistic field
theory, and the emergence of an effective kinetic theory description, is
examined. Even in a weakly-coupled scalar field theory, interesting subtleties
arise at high temperatures where thermal renormalization effects are important.
In this domain, a kinetic theory description in terms of the fundamental
particles ceases to be valid, but one may derive an effective kinetic theory
describing excitations with temperature dependent properties. While the shear
viscosity depends on the elastic scattering of typical excitations whose
kinetic energies are comparable to the temperature, the bulk viscosity is
sensitive to particle non-conserving processes at small energies. As a result,
the shear and the bulk viscosities have very different dependence on the
interaction strength and temperature, with the bulk viscosity providing an
especially sensitive test of the validity of an effective kinetic theory
description.


title:
Angular Correlations in Top Quark Pair Production and Decay at Hadron
  Colliders

abstract:
  We show how to observe sizable angular correlations between the decay
products of the top quark and those of the anti-top quark in top quark pair
production and decay at hadron colliders. These correlations result from the
large asymmetry in the rate for producing like-spin versus unlike-spin top
quark pairs provided the appropriate spin axes are used. The effects of new
physics at production or decay on these correlations are briefly discussed.


title: The Electroweak Phase Transition: A Status Report

abstract:
  A talk presented at "String Gravity and Physics at the Planck Energy Scale",
Erice, September 1995, summarizing the current understanding of the electroweak
phase transition.


title: Nucleon Decay in Non-Minimal Supersymmetric SO(10)

abstract:
  Evaluation of nucleon decay modes and branching ratios in a non-minimal
supersymmetric SO(10) grand unified theory is presented. The non-minimal GUT
considered is the supersymmetrised version of the `realistic' SO(10) model
originally proposed by Harvey, Reiss, and Ramond, which is realistic in that it
gives acceptable charged fermion and neutrino masses within the context of a
phenomenological fit to the low energy standard model inputs. Despite a
complicated Higgs sector, the SO(10) $\underline{10}$ Higgs superfield mass
insertion is found to be the sole contribution to the tree level F-term
governing nucleon decay. The resulting dimension 5 operators that mediate
nucleon decay give branching ratio predictions parameterised by a single
parameter, the ratio of the Yukawa couplings of the $\underline{10}$ to the
fermion generations. For parameter values corresponding to a lack of dominance
of the third family self coupling, the dominant nucleon decay modes are $p
\rightarrow K^{+} + \bar{\nu}_{\mu}$ and $n \rightarrow K^{0} +
\bar{\nu}_{\mu}$, as expected. Further, the charged muon decay modes are
enhanced by two orders of magnitude over the standard minimal SUSY SU(5)
predictions, thus predicting a distinct spectrum of `visible' modes. These
charged muon decay modes, along with $p \rightarrow \pi^{+} + \bar{\nu}_{\mu}$
and $n \rightarrow \pi^{0} + \bar{\nu}_{\mu}$, which are moderately enhanced
over the SUSY SU(5) prediction, suggest a distinguishing fingerprint of this
particular GUT model, and if nucleon decay is observed at Super-KAMIOKANDE the
predicted branching ratio spectrum can be used to determine the validity of
this `realistic' SO(10) SUSY GUT model.


title: Sea Quark or Anomalous Gluon Interpretation for $g_1^p(x)$ ?

abstract:
  Contrary to what has been often claimed in the literature, we clarify that
the hard photon-gluon cross section $\gg_{\rm hard}(x)$ in polarized deep
inelastic scattering calculated in the gauge-invariant factorization scheme
does {\it not} involve any soft contributions and hence it is genuinely {\it
hard}. We show that the polarized proton structure function $g_1^p(x)$ up to
the next-to-leading order of $\alpha_s$ is independent of the factorization
convention, e.g., the gauge-invariant or chiral-invariant scheme, chosen in
defining $\gg_{\rm hard}(x)$ and the quark spin density. Thereby, it is not
pertinent to keep disputing which factorization prescription is correct or
superior. The hard-gluonic contribution to $\Gamma_1^p$, the first moment of
$g_1^p(x)$, is purely factorization dependent. Nevertheless, we stress that
even though hard gluons do not contribute to $\Gamma_1^p$ in the
gauge-invariant scheme, the gluon spin component in a proton, which is
factorization independent, should be large enough to perturbatively generate a
negative sea polarization via the axial anomaly. We briefly comment on how to
study the $Q^2$ evolution of parton spin distributions to the next-to-leading
order of QCD in the chiral-invariant factorization scheme.


title: Gravitational GUT Breaking and the GUT-Planck Hierarchy

abstract:
  It is shown that non-renormalizable gravitational interactions in the Higgs
sector of supersymmetric grand unified theories (GUT's) can produce the
breaking of the unifying gauge group $G$ at the GUT scale $M_{\rm GUT} \sim
10^{16}$~GeV. Such a breaking offers an attractive alternative to the
traditional method where the superheavy GUT scale mass parameters are added ad
hoc into the theory. The mechanism also offers a natural explanation for the
closeness of the GUT breaking scale to the Planck scale. A study of the minimal
SU(5) model endowed with this mechanism is presented and shown to be
phenomenologically viable. A second model is examined where the Higgs doublets
are kept naturally light as Goldstone modes. This latter model also achieves
breaking of $G$ at $M_{\rm GUT}$ but cannot easily satisfy the current
experimental proton decay bound.


title: High-order behaviour and summation methods in perturbative QCD

abstract:
  After reviewing basic facts about large-order behaviour of perturbation
expansions in various fields of physics, I consider several alternatives to the
Borel summation method and discuss their relevance to different physical
situations. Then I convey news about the singularities in the Borel plane, and
discuss the topical subject of the resummation of renormalon chains and its
application in various QCD processes.


title:
The Gegenbauer Polynomial Technique: the evaluation of a class of
  Feynman diagrams

abstract:
  We extend Gegenbauer Polynomials technique to evaluate a class of complicated
Feynman diagrams. New results in the form of $_3F_2$-hypergeometrical series of
unit argument, are presented. As a by-product, we present a new transformation
rule for $_3F_2$-hypergeometric series with argument $-1$.


title: CP Violation in Heavy Neutrino Mediated $e^- e^- \to W^- W^-$

abstract:
  We consider the reaction $e^- e^- \rightarrow W^- W^-$ mediated by possible
heavy neutrino exchange at future LINAC energies of $\sqrt{s}>> 2 m_W$. This
reaction is sensitive to CP phases of the neutrino mixing matrices, even at the
level of Born amplitudes. Certain integrated cross-sections are shown to have
the power to resolve the CP phases when the experimental configurations are
varied. Asymmetries sensitive to CP violation (involving initial QED phases)
for $e^- e^-$ and $e^+ e^+$ reactions are constructed and their consequences
considered.


title: On the Theoretical Status of Deep Inelastic Scattering

abstract:
  The theoretical status of perturbative QED and QCD corrections to deep
inelastic scattering is reviewed.


title:
Solutions to the Schwinger-Dyson equation for the gluon and their
  implications for confinement

abstract:
  Using the Schwinger-Dyson equations the possible infrared behaviour of the
gluon propagator is studied. Previous work performed in axial gauges is
reviewed, the approximations needed detailed and the difficulties of their
justification discussed. We then turn to the Landau gauge and investigate the
possibility of a gluon propagator less singular than $1/p^{2}$ when $p^{2}
\rightarrow 0$. We find that this infrared softened behaviour of the gluon
propagator is inconsistent; only an infrared enhanced gluon, as singular as
$1/p^{4}$ when $p^{2} \rightarrow 0$ is consistent with the truncated
Schwinger-Dyson equation. The implications for confinement and for the
modelling of the Pomeron are discussed.


title: The puzzle of the quark model: Weak radiative hyperon decays

abstract:
  Weak radiative hyperon decays present us with a long-standing puzzle, namely
the question of validity of a hadron-level theorem proved by Hara. We briefly
discuss the conflict between expectations based on Hara's theorem and
experiment as well as the way in which the quark model evades the theorem.
Violation of Hara's theorem in the quark model is traced back to the issue of
hadron compositeness and the nonequivalence of standard ways of imposing
gauge-invariance condition at quark and hadron levels. This suggests that our
understanding of nonlocal composite nature of hadrons may require some
important change.


title: Large-$N_c$ and Chiral Limits of QCD and Models of the Baryon

abstract:
  Two ideas have greatly contributed to our understanding of baryon structure
in the framework of Quantum Chromodynamics (QCD). The first, chiral symmetry,
received its fundamental justification from QCD and has been developed into the
powerful technique of chiral perturbation theory. The other notion is the
large-$N_c$ limit, namely the behavior of QCD in the limit where there are a
large number of colors. Like chiral symmetry, the large-$N_c$ limit predicts
many relations between baryon matrix elements. These so-called
``model-independent'' predictions should agree with each other, but
paradoxically that is not always the case. The paradox is resolved by
recognizing that the two limiting processes (large-$N_c$ and the chiral limit)
do not commute. This noncommutivity can be traced to the special role played by
the $\Delta$ resonance in large-$N_c$ QCD. This gives rise to a new parameter
in the effective theory of baryons.


title: Top Quark Physics -- a Popular Review

abstract:
  The top quark has been discovered at FERMILAB last year. The following
features of top quark physics will be discussed in this article: the top quark
in the standard model production and decay of the top quark in proton
collisions (direct evidence for top) virtual effects of top quarks in
electroweak observables (indirect evidence for top)


title: Searching $R$-parity-violating supersymmetry in semileptonic $B$-decays

abstract:
  If $R$-parity is broken and the photino, although unstable, does not decay
within the detector, then in new semileptonic $B$-decay modes a light ($\sim$
2--3 GeV) photino can be produced carrying missing energy. However, the
photino, being massive, arranges a different kinematical configuration for the
visible decay products as compared to a standard semileptonic event where the
neutrino carries the missing energy. We study the above kinematic distributions
in an attempt to explore the above scenario.


title:
Phenomenological Constraints on the Higgs as Pseudo-Goldstone Boson
  Mechanism in Supersymmetric GUT Theories

abstract:
  There are few robust solutions to the doublet-triplet splitting problem in
supersymmetric GUT theories. One of the more promising solutions is the Higgs
as pseudo-Goldstone boson mechanism. In its minimal implementation, such a
solution places an additional restriction on the parameter space of the minimal
supersymmetric standard model. A testable consequence of this constraint is an
equation for $\tan \beta$. We present this restriction and study its solutions
in order to constrain the allowed parameter space. Thus the assumptions on the
GUT scale Higgs sector should yield testable predictions for weak scale
physics. If the SUSY parameters are measured then it should be possible to
check the predictions, yielding insight into GUT scale physics.


title:
Coulomb Final State Interaction in Pion Interferometry for the Processes
  of High Multiplicity

abstract:
  The corrections for two pion correlations due to electromagnetic final state
interactions at high secondary multiplicities are investigated. It is shown
that these result in a noticeable deviation from the standard Gamov factor.
This conclusion changes drastically in a model of the pion system with
expansion. The critical parameter which determines the size of these effects is
found to be the ratio of the relative velocity of detected pions to the
velocity of the pair center-of-mass (in the fireball rest frame). In
particular, when this parameter is much less than unity the pion pair escapes
the initial high density region promptly and the distortion of the mutual
Coulomb potential is weak.


title: Hadronic Rare $B$ Decays via Exchange or Annihilation Diagrams

abstract:
  The two-body mesonic $B$ decays induced only via a single $W$-exchange or
annihilation quark diagram, such as $B^-_u\rightarrow D^{(*)-}_sK^{(*)0}$ and
$\bar{B}^0_d\rightarrow D^{(*)+}_sK^{(*)-}$, are analyzed in the factorization
approximation. We estimate the branching ratios for those transitions into two
pseudoscalar mesons, and find them to be negligibly small. The significant
effect of final-state rescattering is illustrated by taking $B^-_u\rightarrow
D^-\bar{K}^0$ for example.


title:
Breakdown of Conventional Factorization for Isolated Photon Cross
  Sections

abstract:
  Using $e^+e^-\rightarrow\gamma + X$ as an example, we show that the
conventional factorization theorem in perturbative quantum chromodynamics
breaks down for isolated photon cross sections in a well defined part of phase
space. Implications and physical consequences are discussed.


title: Fermion number violation in heavy fermion decay

abstract:
  The presence of a heavy fermion doublet of fourth generation in the standard
model would lead to a anomalous decay with fermion number non-conservation. The
anomalous decay path in the background of the electroweak instanton is
demonstrated by numerical calculation. If the mass of fermion exceeds the
critical value $m_f^{\rm cr}$=9.2 TeV (for $M_H=M_W$), it is shown that there
exists the rapid anomalous decay of the heavy fermion in semi-classical
approximation. The dependence of the critical fermion mass on the Higgs mass is
also presented.


title:
Gauge-fixing parameter dependence of two-point gauge variant correlation
  functions

abstract:
  The gauge-fixing parameter $\xi$ dependence of two-point gauge variant
correlation functions is studied for QED and QCD. We show that, in three
Euclidean dimensions, or for four-dimensional thermal gauge theories, the usual
procedure of getting a general covariant gauge-fixing term by averaging over a
class of covariant gauge-fixing conditions leads to a nontrivial gauge-fixing
parameter dependence in gauge variant two-point correlation functions (e.g.
fermion propagators). This nontrivial gauge-fixing parameter dependence
modifies the large distance behavior of the two-point correlation functions by
introducing additional exponentially decaying factors. These factors are the
origin of the gauge dependence encountered in some perturbative evaluations of
the damping rates and the static chromoelectric screening length in a general
covariant gauge. To avoid this modification of the long distance behavior
introduced by performing the average over a class of covariant gauge-fixing
conditions, one can either choose a vanishing gauge-fixing parameter or apply
an unphysical infrared cutoff.


title: Production of $J/\psi$-pairs at HERA-$\vec{{\rm N}}$

abstract:
  The production of $J/\psi$-pairs as a possible measure of the polarized gluon
distribution $\Delta G(x)$ is studied for proton--nucleon collisions at
$\sqrt{s} =40\;\mbox{GeV}^2$ (HERA-$\vec{{\rm N}}$). Possibilities of
reconstructing the helicity state of at least one of the $J/\psi$'s are
critically reviewed. The observation of production asymmetries in the single
polarized mode of HERA-$\vec{{\rm N}}$ is found to be not feasible.


title: Solar Neutrinos: Where We Are, Where We Are Going

abstract:
  This talk answers a series of questions. Why study solar neutrinos? What does
the combined standard model (solar plus electroweak) predict for solar
neutrinos? Why are the calculations of neutrino fluxes robust? What are the
three solar neutrino problems? What have we learned in the first thirty years
of solar neutrino research? For the next decade, what are the most important
solvable problems in the physics of solar neutrinos? What are the most
important problems in the astrophysics of solar neutrinos?


title:
Reconciliation of effective potential calculations of the lower bound
  for the Higgs boson mass

abstract:
  We comment on different results from three recent effective potential
calculations of the Higgs mass lower bound.


title: Gravity and Effective Field Theory: A Talk for Phenomenologists

abstract:
  I briefly summarized some recent work which uses the techniques of effective
field theory to make quantum predictions in general relativity. In contrast to
conventional expectations, these are in fact well behaved. The leading quantum
correction to the interaction of two heavy masses is used as a specific
example.


title: Supersymmetry and R_b in the light of LEP 1.5

abstract:
  We re-examine the possible magnitude of the supersymmetric contribution to
$R_b\equiv\Gamma(Z^0\to\bar b b)/\Gamma(Z^0\to{\rm all})$ in the light of the
constraints imposed by the absence of light charginos at LEP~1.5, implementing
also other available phenomenological constraints. We find the supersymmetric
contribution to be $R^{\rm susy}_b < 0.0017$, and discuss the extent to which
this upper bound could be strengthened by future constraints on the chargino
and top-squark masses. Such values of $R^{\rm susy}_b$ tend to disfavor a
supersymmetry explanation of the apparent $R_b$ discrepancy.


title: Left-Right Asymetry From Supersymmetry in Polarized M{\o}ller Scattering

abstract:
  We calculate the leading contribution to the left-right asymmetry in
polarized M{\o}ller scattering from the superpartners in the Minimal
Supersymmetric Standard Model (MSSM), using an effective lagrangian approach.
We determine the maximum asymmetry that can result from the superpartners in
the MSSM under different scenarios, and discuss the feasibility of a
high-precision, low-energy ($\sqrt{s}\approx 200~{\rm MeV}$) M{\o}ller
scattering experiment to see supersymmetry.


title: Bubble Collisions and Defect Formation in a Damping Environment

abstract:
  Within the context of a first-order phase transition in the early Universe,
we study the collision process for vacuum bubbles expanding in a plasma. The
effects of the plasma are simulated by introducing a damping term in the
equations of motion for a $U(1)$ global field. We find that Lorentz-contracted
spherically symmetric domain walls adequately describe the overdamped motion of
the bubbles in the thin wall approximation, and study the process of collision
and phase equilibration both numerically and analytically. With an analytical
model for the phase propagation in 1+1 dimensions, we prove that the phase
waves generated in the bubble merging are reflected by the walls of the true
vacuum cavity, giving rise to a long-lived oscillating state that delays the
phase equilibration. The existence of such a state in the 3+1 dimensional model
is then confirmed by numerical simulations, and the consequences for the
formation of vortices in three-bubble collisions are considered.


title:
Renormalized diffractive cross sections at HERA and the structure of the
  pomeron

abstract:
  A phenomenological renormalization scheme for hadronic diffraction is
proposed, which achieves unitarization without the need for "screening
corrections". Predictions for diffractive photoproduction cross sections at
HERA are presented and compared with experimental results. A new interpretation
of hard and deep inelastic diffractive data emerges, in which the momentum sum
rule is obeyed by the constituents of a pomeron described as a mixture of quark
and gluon color singlets in a ratio dictated by asymptopia.


title: Spin Correlation in Top-Quark Production at Hadron Colliders

abstract:
  We propose techniques to observe the correlation of the spins of top quarks
and antiquarks at the Tevatron and the LHC. Observation of the spin correlation
would confirm that the top quark decays before its spin flips, and would place
a lower bound on the top-quark width and V_tb. The spin correlation may also be
a useful tool to study the weak decay amplitude of the top quark.


title:
Different Nuclear Dependence of $J/\psi$ and $\psi^{\prime}$ Production
  in p-A and A-p Collisions

abstract:
  While presently available p-A data observe that the nuclear dependence of
$J/\psi$ and $\psi^{\prime}$ production is the same within errors, we show that
different nuclear dependence of $J/\psi$ and $\psi^{\prime}$ production in the
kinematic region uncovered by the present p-A data can be predicted based on
two different nuclear absorption scenarios. It is found that the predicted
production ratio $\sigma (\psi^{\prime})/\sigma (J/\psi)$ at positive $x_F$ in
A-p collisions is mainly determined by nuclear absorption, and hence allows
direct experimental test of nuclear absorption scenarios.


title: Heavy Quark Solitons in the Nambu--Jona-Lasinio Model

abstract:
  The Nambu--Jona-Lasinio model (NJL) is extended to incorporate heavy quark
spin-symmetry. In this model baryons containing one heavy quark are analyzed as
bound-states of light baryons, represented as chiral solitons, and mesons
containing one heavy quark. From related studies in Skyrme type models, the
ground-state heavy baryon is known to arise for the heavy meson in a P--wave
configuration. In the limit of an infinitely large quark mass the heavy meson
wave-function is sharply peaked at the center of the chiral soliton. Therefore
the bound state equation reduces to an eigenvalue problem for the coefficients
of the operators contained in the most general P-wave {\it ansatz} for the
heavy meson. Within the NJL model a novel feature arises from the coupling of
the heavy meson to the various light quark states. In this respect conceptual
differences to Skyrme model calculations are discovered: The strongest bound
state is given by a heavy meson configuration which is completely decoupled
from the grand spin zero channel of the light quarks.


title: Probability and Measurement Uncertainty in Physics - a Bayesian Primer

abstract:
  Bayesian statistics is based on the subjective definition of probability as
{\it ``degree of belief''} and on Bayes' theorem, the basic tool for assigning
probabilities to hypotheses combining {\it a priori} judgements and
experimental information. This was the original point of view of Bayes,
Bernoulli, Gauss, Laplace, etc. and contrasts with later ``conventional''
(pseudo-)definitions of probabilities, which implicitly presuppose the concept
of probability. These notes show that the Bayesian approach is the natural one
for data analysis in the most general sense, and for assigning uncertainties to
the results of physical measurements - while at the same time resolving
philosophical aspects of the problems. The approach, although little known and
usually misunderstood among the High Energy Physics community, has become the
standard way of reasoning in several fields of research and has recently been
adopted by the international metrology organizations in their recommendations
for assessing measurement uncertainty.
  These notes describe a general model for treating uncertainties originating
from random and systematic errors in a consistent way and include examples of
applications of the model in High Energy Physics, e.g. ``confidence intervals''
in different contexts, upper/lower limits, treatment of ``systematic errors'',
hypothesis tests and unfolding.

categories: hep-ph astro-ph bayes-an cond-mat physics.data-an


title:
$\gamma \gamma \to \pi \pi \pi$ to One Loop in Chiral Perturbation
  Theory

abstract:
  The $\gamma\gamma \to \pi^0 \pi^0 \pi^0$ and $\gamma\gamma \to \pi^+ \pi^-
\pi^0$ amplitudes are discussed in the general context of Chiral Perturbation
Theory (ChPT) to $O(p^6)$. Chiral loops are found to play a major role. This
makes these processes a good test of ChPT, mainly in its anomalous sector. We
correct earlier numerical results at tree level and determine the one-loop
results as well.


title:
$F_2/xG(x,Q^2)$ Ratio at Small $x$ and the Role of the Contribution from
  Infrared Region

abstract:
  We consider the light quark electroproduction cross section and show that the
contribution coming from the infrared ($q_T<300\, MeV$) region is not
negligible. It changes the $F_2(x,Q^2)/xG(x,Q^2)$ ratio by 20-30\% (or even
more) for small $x$ and $Q^2\sim 4\, GeV^2$.


title: Are Four-Fermion Operators Relevant for the Fermion Mass Problem?

abstract:
  Four-fermion operators may have large anomalous scaling and become relevant
operators in some strongly interacting gauge theories. We present a detailed
model which illustrates some of the implications of such operators for the
generation of quark and lepton masses. Such operators would originate at high
scales where quarks and leptons experience a new strong interaction, but no
unbroken technicolor interaction is required. The breakdown of both the new
gauge symmetry and electroweak gauge symmetry is associated with a dynamical
TeV mass for fourth family quarks. Among the new physics signatures are
anomalous (chromo)magnetic moments and their flavor-changing counterparts.


title: Forward-Backward Asymmetries in Hadronically Produced Lepton Pairs

abstract:
  It has now become possible to observe appreciable numbers of hadronically
produced lepton pairs in mass ranges where the contributions of the photon and
$Z^0$ are comparable. Consequently, in the reaction $p \bar p \to \ell^- \ell^+
+ \ldots$, substantial forward-backward asymmetries can be seen. These
asymmetries provide a test of the electroweak theory in a new regime of
energies, and can serve as diagnostics for any new neutral vector bosons
coupling both to quarks and to charged lepton pairs.


title: Charmed Hadron Asymmetries in the Intrinsic Charm Coalescence Model

abstract:
  Fermilab experiment E791, measuring charmed hadron production in $\pi^- A$
interactions at 500 GeV with high statistics, has observed a strong asymmetry
between the hadroproduction cross sections for leading $D$ mesons which contain
projectile valence quarks and the nonleading charmed mesons without projectile
valence quarks. Such correlations of the charge of the $D$ meson with the
quantum numbers of the beam hadron explicitly contradict the factorization
theorem in perturbative QCD which predicts that heavy quarks hadronize through
a jet fragmentation function that is independent of the initial state. The E791
experiment also measures $\Lambda_c/ \bar \Lambda_c$ and $D_s/\bar{D_s}$
production asymmetries as well as asymmetries in $D \bar D$ pair production. We
examine these asymmetries and the fractional longitudinal momentum, $x_F$,
distributions for single and pairs of charmed hadrons within a two-component
model combining leading-twist $g g$ and $q \bar q$ fusion subprocesses with
charm production from intrinsic heavy quark Fock states. A key feature of this
analysis is intrinsic charm coalescence, the process by which a charmed quark
in the projectile's Fock state wavefunction forms charmed hadrons by combining
with valence quarks of similar rapidities.


title:
Initial State Radiative Corrections to $Z^0$\ Pair Production in $e^+
  e^-$\ Annihilation -- The Semi-Analytical Approach

abstract:
  A total and differential cross-section calculation for the Electroweak
Standard Model reaction $e^+ e^- \rightarrow (Z^0 Z^0) \rightarrow
f_1\bar{f_1}f_2\bar{f_2}(\gamma)$\ including the effects of the finite $Z^0$\
width and, for the first time, all QED initial state radiative corrections
(ISR) is presented. A semi-analytical technique is used: All angular phase
space integrations, five for the tree level process, seven if ISR is included,
are carried out analytically. The remaining phase space variables are the
invariant masses of the two decaying $Z^0$\ bosons for tree level plus the
reduced center of mass energy squared in the ISR case. Invariant masses are
submitted to high precision numerical integration. Semi-analytical and
numerical results for $e^+ e^-$\ center of mass energies between
$\sqrt{s}=130$GeV and $1$TeV are reported. It is shown that the radiatively
corrected cross-section splits into a universal, leading logarithm part with
the tree level cross-section factorizing on one hand and a non-universal
contribution on the other hand. A generalization to the case of Standard Model
neutral boson pair production, $e^+ e^- \rightarrow (Z^0 Z^0, Z^0 \gamma,
\gamma\gamma) \rightarrow f_1\bar{f_1} f_2\bar{f_2}(\gamma)$, is worked out in
detail. The relevance of the presented calculation for the phenomenology of
$e^+ e^-$\ collider physics is discussed, especially for $W$ and Higgs physics
both of which will be important topics in the near future. All significant
technical details of the calculation are explained.


title: A New Supersymmetric Framework for Fermion Masses

abstract:
  Supersymmetric theories involving a spontaneously broken flavor symmetry can
solve the flavor-changing problem while having quark and lepton masses derived
from both $F$ and $D$ terms. As an example, a theory of leptons is constructed
in which holomorphy constrains the electron to be massless at tree level. The
electron flavor symmetries are broken by D terms, leading to flavor mixing in
the slepton mass matrices, which allows a radiative electron mass to be
generated by the gauge interactions of supersymmetric QED. Such a radiative
origin for the electron mass can be probed by searches for $\tau \rightarrow e
\gamma$, and could be verified or eliminated by measurements of slepton pair
production.


title:
The Extraction of $V_{ub}$ from Inclusive B Decays and the Resummation
  of End Point Logs

abstract:
  In this paper we discuss the theoretical difficulties in extracting $V_{ub}$
using the data from inclusive B decays. Specifically, we address the issue of
the end point singularities. We perform the resummation of both the leading and
next to leading end point logs and include the leading corrections to the hard
scattering amplitude. We find that the resummation is a $20\%-50\%$ effect in
the end point region where the resummation is valid. Furthermore, the resummed
sub-leading logs dominate the resummed double logs. The consequences of this
result for a model independent extraction of the mixing angle $V_{ub}$ are
explored.


title:
Quantum Decoherence of Subcritical Bubble in Electroweak Phase
  Transition

abstract:
  In a weakly first order phase transition the typical scale of a subcritical
bubble calculated in our previous papers turned out to be too small. At this
scale quantum fluctuations may dominate and our previous classical result may
be altered. So we examine the critical size of a subcritical bubble where
quantum-to-classical transition occurs through quantum decoherence. We show
that this critical size is almost equal to the typical scale which we
previously obtained.


title:
Off-shell pion structure function and flavor asymmetry in the nucleon
  sea

abstract:
  We study off-shell effects of the pion cloud on the sea quark distribution in
the nucleon. The structure function of the off-mass-shell pion is obtained
within the Nambu and Jona-Lasinio model, where the shape of the distribution
function depends on the pion momentum. By using the momentum dependent pion
structure function, the SU(2) flavor asymmetry in the nucleon see is reexamined
within the pionic model, in which the sea quark distribution of the nucleon is
given as a convolution of the off-shell pion structure function. We calculate
experimentally observed quantities related to the SU(2) asymmetry of the
nucleon sea such as the Gottfried sum and the Drell-Yan cross section ratios,
and find these quantities are insensitive to the off-shell effects of the pions
structure function. However, the $x$ dependence of $\bar{u}-\bar{d}$ calculated
with the off-shell structure function shows a clear deviation from the result
with the on-shell one. We evaluate also the cross section of semi-inclusive
lepton-nucleon process with a slow nucleon production to demonstrate the
off-shell effect to be checked experimentally.


title: New Signatures of Squarks

abstract:
  When the gluino is light and long lived, missing energy is a poor signature
for both squarks and gluinos. Instead, $S_q S_q^*$ production in $e^+ e^-$ and
$p \bar{p}$ collisions characteristically results in events with $\ge 4$ jets.
Methods are proposed for deciding whether an observed excess of 4-jet events is
due to $S_q S_q^*$ production. The recent report by ALEPH of observation of 14
4-jet events when 7 were expected is discussed.


title:
Probing the heavy Higgs mass by the measurement of the Higgs decay
  branching ratios in the minimal supersymmetric standard model

abstract:
  We examine whether the parameters in the Higgs sector of the minimal
supersymmetric standard model can be determined by detailed study of production
cross section and decay branching ratios of the Higgs particle. Assuming that
the lightest CP-even Higgs boson ($h$) is observed at a future $e^+ e^-$ linear
collider with $\sqrt{s}=300\sim500$GeV, we show that the value of CP-odd scalar
mass is determined from the ratio of the two branching ratios, $Br(h\to
b\bar{b})$ and $Br(h\to c\bar{c})+Br(h\to gg)$, almost independently of the
stop mass scale.


title: Weak Radiative Decays of Hyperons and of Charm and Beauty Baryons

abstract:
  A review is presented of the weak radiative decays of baryons.It includes an
anlysis of the possible contributions of electromagnetic penguins to these
decays,a survey of the difficulties still encountered in the sector of hyperon
decays and a short account on some new developments on this topic. The
theoretical treatments on charm and beauty baryon decays are summarized,with a
good outlook for their detection.


title: Small$-x$ Resummation Effects in Electroweak Processes

abstract:
  We investigate small$-x$ resummation effects in QCD coefficient functions for
$Z_0g$ and $Wg$ fusion processes, and we compare them with the known ones of
$\gamma g$ type. We find a strong process dependence, that we argue to be due
to the possible presence of collinear singularities for either small or large
$\k$ of the exchanged gluon. For top quark production, we find that the $gg\ra
t\bar{t}$ and $Z_0g\ra t\bar{t}$ channels have larger resummation enhancements
than the $Wg\ra t\bar{t}$ one.


title:
A new possibility to monitor collisions of relativistic heavy ions at
  LHC and RHIC

abstract:
  We consider the radiation of particles of one bunch in the collective field
of the oncoming bunch, called coherent bremsstrahlung (CBS). The main
characteristics of CBS for LHC (in the Pb-Pb mode) and for RHIC are calculated.
At LHC about $3.9 10^8 dE_\gamma/E_\gamma$ photons per second are expected for
photon energies $E_\gamma \stackrel{<} {\sim} E_c= 93 $ eV. It seems that CBS
can be a potential tool for optimizing collisions and for measuring beam
parameters. The bunch length can be found from the critical energy of the CBS
spectrum; the transverse bunch size is related to the photon rate. A specific
dependence of photon rate on the impact parameter between the beams allows for
a fast control over the beam displacement.


title: Extended Gauge Models at e+e- Colliders

abstract:
  We summarize the potential of high--energy $\ee$ linear colliders for
discovering, and in case of discovery, for studying the signals of extended
gauge models. We will mainly focus on the virtual signals of new neutral gauge
bosons and on the production of new heavy leptons. [Invited talk given at the
Workshop on Physics and Experiments with Linear Colliders, Morioka-Appi, Japan,
September 8-12 1995.]


title: Heavy Higgs Bosons at TeV e+e- Colliders

abstract:
  We summarize the work done by the European working group on Higgs Particles
for the Workshop ``Physics with e$^+$e$^-$ Linear Colliders", Annecy--Gran
Sasso--Hamburg, Feb.--Sept. 1995. The main focus will be on the physics
possibilities at a second phase e$^+$e$^-$ linear collider with a center of
mass energy of $\sim 1.5$ TeV.


title: Implications of a Higgs Discovery at LEP

abstract:
  If the Higgs boson has a mass below 130 GeV, then the standard model vacuum
is unstable; if it has a mass below 90 GeV (i.e. within reach of LEP within the
next two years), then the instability will occur at a scale between 800 GeV and
10 TeV. We show that precise determinations of the Higgs and top quark masses
as well as more detailed effective potentialcalculations will enable one to pin
down the location of the instability to an accuracy of about 25 percent. It is
often said that ``the standard model must break down'' or ``new physics must
enter'' by that scale. However, by considering a toy model for the new physics,
we show that the lightest new particle (or resonance) could have a mass as much
as an order of magnitude greater than the location of the instability, and
still restabilize the vacuum.


title: Initial-conditions problem for a Chiral Gross-Neveu system

abstract:
  A time-dependent projection technique is used to treat the initial-value
problem for self-interacting fermionic fields. On the basis of the general
dynamics of the fields, we derive formal equations of kinetic type for the set
of one-body dynamical variables. A nonperturbative mean-field expansion can be
written for these equations. We treat this expansion in lowest order, which
corresponds to the Gaussian mean-field approximation, for a uniform system
described by the Chiral Gross-Neveu Hamiltonian. Standard stationary features
of the model, such as dynamical mass generation due to chiral symmetry breaking
and a phenomenon analogous to dimensional transmutation, are reobtained in this
context. The mean-field time evolution of non-equilibrium initial states is
discussed.


title:
Strange--Beauty Meson Production by Fragmentation in Proton--Antiproton
  Collisions

abstract:
  The cross sections for the production of $B_s$ and $B_s^*$ mesons through the
fragmentation process in $\bar{p}p$ collisions were calculated. The input
parameters were determined from the measured $B_s$ and $B_s^*$ production rates
in $e^+e^-$ annihilation. The transverse momentum distributions
$d\sigma/dp_{T}$ are given for $\sqrt{s}=1.8$ TeV, the Fermilab Tevatron
energy.


title: A Screened BFKL Interpretation of $F_2$ in the Exceedingly Small x Limit

abstract:
  In this letter we show that the behaviour of $F_{2}$, at very small $x_B$,
agrees with the behaviour expected from the BFKL evolution equation, when
screening corrections are included. We obtain a description which is consistent
with the data, however, we require the screening corrections to be relatively
large (about a quarter of the total DIS cross section). The relation between
the screening corrections and the diffractive DIS cross section is discussed.


title: Fourth-Generation Leptons at LEP2

abstract:
  From non-observation at LEP1, a lower mass limit of 45 GeV has been
established on any additional sequential fermion beyond the three generations.
Precision measurements have further constrained the number of such additional
generations, either degenerate or nearly so, to be at most one. LEP2, an
energy-upgraded version of LEP1, would provide greater mass-reach in the search
for such particles. We study the pair-production of fourth-generation leptons
for various LEP2 energy options. We find that in most cases such particles
could be discovered/ruled out up to the kinematic limit.


title: Calculating the $Q\bar{Q}$ Potential in 2+1 Dimensional Light-Front QCD

abstract:
  Pure glue QCD is formulated on a 2+1 dimensional transverse lattice, using
discrete light-front quantization. The transverse component of the gauge fields
is taken to be compact, but in a linearized approximation with an effective
potential. The (rest-frame) $Q\bar{Q}$ potential is evaluated numerically using
Lanzcos matrix diagonalization. We first discuss the strong coupling limit
analytically and then present numerical results beyond the strong coupling
limit. The physical origin of confinement on a transverse lattice depends on
the orientation of the external charges: For longitudinally separated charges,
confinement arises from the instantaneous Coulomb interaction and for
transversely separated quarks a string of link-fields forms. In the general
case one obtains a superposition of both effects. Despite the asymetry in the
microscopic mechanism, already a very simple ansatz for the effective
link-field potential provides an almost rotationally invariant $Q\bar{Q}$
potential. The momentum carried by the glue depends strongly on the orientation
of the external charges, which might have observable consequences.


title: QCD Equalities for Baryon Current Matrix Elements

abstract:
  An examination of the symmetries manifest in the QCD path integral for
current matrix elements reveals various equalities among the quark sector
contributions. QCD equalities among octet baryon magnetic moments lead to a
determination of the disconnected sea-quark contribution to nucleon magnetic
moments, which is the most reliable determination in the literature. Matching
QCD equalities to recent calculations of decuplet baryon magnetic moments in
chiral perturbation theory (ChiPT) reveals an equivalence between ChiPT to
order $p^2$ and the simple quark model with an explicit disconnected sea-quark
contribution. New insights into SU(3)-flavor symmetry breaking, sea
contributions and constituent quark composition are obtained. The strangeness
contribution to nucleon magnetic moments is found to be large at $G_M^s(0) =
-0.75 \pm 0.30\ \mu_N$. The QCD equalities must be followed by any model which
hopes to capture the essence of nonperturbative QCD. Not all models are in
accord with these symmetries.


title:
Hadronic $\psi$ production calculated in the NRQCD factorization
  formalism

abstract:
  The NRQCD factorization formalism of Bodwin, Braaten, and Lepage prescribes
how to write quarkonium production rates as a sum of products of short-distance
coefficients times non-perturbative long-distance NRQCD matrix elements. We
present, in the true spirit of the factorization formalism, a detailed
calculation of the inclusive cross section for hadronic $\psi$ production. We
find that in addition to the well known {\it color-singlet} production
mechanisms, there are equally important mechanisms in which the $c\bar{c}$ pair
that forms the $\psi$ is initially produced in a {\it color-octet} state, in
either a ${}^3S_1$, ${}^1S_0$, ${}^3P_0$ or ${}^3P_2$ angular-momentum
configuration. In our presentation, we emphasize the ``matching'' procedure,
which %is the method that allows us to determine the short-distance
coefficients appearing in the factorization formula. We also point out how one
may systematically include relativistic corrections in these calculations.


title: Nucleosynthesis Limits on the Mass of Long Lived Tau and Muon Neutrinos

abstract:
  We compute the nucleosynthesis bounds on the masses of stable Dirac and
Majorana neutrinos by solving an evolution equation network comprising of all
neutrino species which in the Dirac case includes different helicity states as
separate species. We will not commit ourselves to any particular value of the
nucleosynthesis bound on effective number of light neutrino degrees of freedom
$N_\nu$, but present all our mass bounds as {\em functions} of $\dNu$. For
example, we find that the excluded region in the mass of a Majorana $\mu$- or
$\tau$- neutrino, $0.31$ MeV $< m_{\nu}^M < 52$ MeV corresponding to a bound
$\dNu < 0.3$ gets relaxed to $0.93$ MeV $< m_{\nu}^M < 31$ MeV if $\dNu < 1.0$
is used instead. For the Dirac neutrinos this latter constraint gives the upper
limits (for $T_{\rm QCD} = 100$ MeV): $\mnm < 0.31$ MeV and $\mnt < 0.37$ MeV.
Also, the constraint $\dNu <1$ {\it allows} a stable Dirac neutrino with
$m^D_{\nu_\tau} > 22$ MeV.


title: Lambda_b-Polarization from its Inclusive Semileptonic Decay

abstract:
  We discuss the Lambda_b-polarization of the bottom baryon Lambda_b in its
production and in its decay. Standard Model predictions for b-quark
polarization on the Z-peak are reviewed, including beam-quark orientation
effects and O(as) radiative corrections to the polarization. The b-quark
polarization is expected to be handed over to the Lambda_b into which it
fragments with a high degree of efficiency. We present several spin-momentum
correlation measures of the spin of the \Lambda_b with the momenta of its decay
products in its inclusive semileptonic decay. We estimate the strengths of the
spin-momentum correlations in the Free Quark Decay (FQD) model and find that
some of the measures provide good or very good analyzing power for measuring
the polarization of the Lambda_b.


title: $Z_3$ Twisted Chiral Condensates in QCD at Finite Temperatures

abstract:
  It was recently observed in a lattice QCD measurement that the chiral
condensate in the quenched approximation shows dramatically different behavior
in the three $Z_3$-equivalent de-confined phases. We argue that this phenomenon
can be understood qualitatively as an effect of $Z_3$ twists on fermionic
fields. Quarks under these $Z_3$-twists become global anyons and hence display
different thermodynamic properties. We further show that the lattice data can
be roughly modeled by a Nambu-Jona-Lasinio type Lagrangian with a minimal
coupling to a constant gauge field $A_0=2\pi nT/3$ (with $n=0$, $\pm1$), which
arises naturally from the non-trivial phase of the Polyakov line.


title:
Photoproduction of neutral pion pairs in the Coulomb field of the
  nucleus

abstract:
  The total cross section for Coulomb photoproduction of neutral pion pairs in
the reaction gamma A --> pi0 pi0 A is estimated within the effective chiral
lagrangian approach.
  The amplitude of gamma gamma* --> pi0 pi0 with one off-shell photon is
calculated at O(p^6) in the momentum expansion; in addition, nuclear absorption
is taken into account.
  Besides its experimental feasibility, the results of the calculation
demonstrate that the reaction gamma A --> pi0 pi0 A is a powerful source of
information on the process gamma gamma --> pi0 pi0 close to threshold.


title: Thresholds in $\alpha_s$ evolution and the $p_T$ dependence of jets

abstract:
  We point out that high-mass thresholds in the evolution of the
strong-interaction coupling parameter $\alpha_s$, due to gluinos, squarks and
possible new heavy quarks, could introduce appreciable corrections to the
transverse momentum dependence of jet production at the Tevatron. If the new
thresholds were near scale $\mu = 200$~GeV, then within the limits of
asymptotic freedom they could introduce up to $11\%$ increase in
$\alpha_s(\mu)$ (and hence $23\%$ increase in jet production) at scale
$\mu=500$ GeV, compared to Standard Model extrapolations.


title: Strangeness in the Nucleon: The Strange Vector Form Factors

abstract:
  We discuss two descriptions of the nucleon's strange vector form factors in
the framework of vector meson dominance. The first, an updated and extended
version of Jaffe's dispersion analysis, approximates the spectral functions of
the form factors as a sum of vector meson poles, whereas the second combines
vector meson dominance in the $\omega$ and $\phi$ meson sector with an
intrinsic strangeness distribution from a kaon cloud. (Plenary talk given at
the International School for Nuclear Physics, 17th Course: Quarks and Hadrons
in Nuclei, Erice, Sicily, Sept 19-27, 1995.)


title:
Radiative Corrections to the Muonium Hyperfine Structure. I. The
  $\alpha^2 (Z\alpha)$ Correction

abstract:
  This is the first of a series of papers on a systematic application of the
NRQED bound state theory of Caswell and Lepage to higher-order radiative
corrections to the hyperfine structure of the muonium ground state. This paper
describes the calculation of the $\alpha^2 (Z\alpha)$ radiative correction. Our
result for the complete $\alpha^2 (Z\alpha)$ correction is 0.424(4) kHz, which
reduces the theoretical uncertainty significantly. The remaining uncertainty is
dominated by that of the numerical evaluation of the nonlogarithmic part of the
$\alpha (Z\alpha )^2$ term and logarithmic terms of order $\alpha^4$.


title: Three-jet cross sections to next-to-leading order

abstract:
  One- and two-jet inclusive quantities in hadron collisions have already been
calculated to next-to-leading order accuracy, using both the subtraction and
the cone method. Since the one-loop corrections have recently been obtained for
all five-parton amplitudes, three-jet inclusive quantities can also be
predicted to next-to-leading order. The subtraction method presented in the
literature is based on a systematic use of boost-invariant kinematical
variables, and therefore its application to three-jet production is quite
cumbersome. In this paper we re-analyze the subtraction method and point out
the advantage of using angle and energy variables. This leads to simpler
results and it has complete generality, extending its validity to $n$-jet
production. The formalism is also applicable to $n$-jet production in $e^+e^-$
annihilation and in photon-hadron collisions. All the analytical results
necessary to construct an efficient numerical program for next-to-leading order
three-jet inclusive quantities in hadroproduction are given explicitly. As new
analytical result, we also report the collinear limits of all the two-to-four
processes.


title: Semiclassical Approach to Structure Functions at Small x

abstract:
  Inclusive and diffractive structure functions for electron-proton scattering
are calculated in a semiclassical approach at large momentum transfer $Q^2$ and
small values of the scaling variable $x$. The basic process is the production
of a quark-antiquark pair in the colour field of the proton. The structure
functions are expressed in terms of Wilson lines along the classical
trajectories of quark and antiquark passing through the colour field, and their
covariant derivatives. Based on some rather general assumptions on properties
of the colour field, inclusive and diffractive structure functions are
evaluated in terms of four field dependent constants.


title: Improved variables for measuring the $Lambda_b$ polarization

abstract:
  We discuss a few possible strategies for measuring the polarization of the
$\Lambda_{\mathrm{b}}$ baryons produced in $e^+e^-$-annihilation at the
$\mathrm{Z}$ resonance through their inclusive semileptonic decays. After
reviewing the existing methods, a new method is proposed, based on the ratio of
the averages of the squared electron and neutrino energy, including both
perturbative and nonperturbative corrections. This variable minimizes the
statistical error on the $\Lambda_{\mathrm{b}}$ polarization, while keeping the
systematic theoretical errors at the level of 1-2%. A number of other
polarization-sensitive variables are also discussed, such as averages of ratios
of the electron and neutrino energy and the distribution in the difference of
the electron and neutrino rapidities.


title: Top Quark Pair Production in the Threshold Region

abstract:
  Recent results on production and decays of polarized top quarks are reviewed.
Top quark pair production in $e^+e^-$ annihilation is considered near energy
threshold. For longitudinally polarized electrons the produced top quarks and
antiquarks are highly polarized. Dynamical effects originating from strong
interactions and Higgs boson exchange in the $t-\bar t$ system can be
calculated using the Green function method. Energy-angular distributions of
leptons in semileptonic decays are sensitive to the polarization of the
decaying top quark and to the Lorentz structure of the weak charged current.


title:
Neutron electric dipole moment in a supersymmetric model with singlet
  quarks

abstract:
  The neutron electric dipole moment is investigated in a supersymmetric
electroweak model admitting $ {\rm SU(2)}_W $ singlet and $ Q = -1/3 $, say $ D
$-type, quarks. Significant $ CP $ violating phases appear in the coupling
between the singlet $ D $-type quarks and the ordinary $ d $-type quarks. Then,
through the $ d $-$ D $ mixing effects on the squark mass terms the gluino
one-loop diagrams provide naturally the contributions $ \sim 10^{-26} e~{\rm
cm} $ comparable to the current experimental bound on the neutron electric
dipole moment. The $ CP $ violation in the $ d $-$ D $ coupling would also be
relevant for the electroweak baryogenesis.


title: Goldstone modes and the Higgs condensation beyond one loop

abstract:
  We study the Higgs condensation $H={\bar t}t$ mechanism in the Top-mode
Standard Model at the next-to-leading order in 1/Nc. The calculation includes
the effects of the Goldstone fields, but not the effects of the transverse
components of the electroweak gauge bosons. The resulting effective theory is
parametrized by means of a finite energy cut-off $\L$ at which the condensation
is supposed to take place. Demanding that the next-to-leading order
contributions not dominate over the leading order ones, we get a rather low
bound for the cut-off: $\L = O(1 TeV)$. QCD effects can change the results
somewhat, but the basic conclusions remain unchanged. The inclusion of the
Goldstone degrees of freedom tends to decrease the bound on $\L$.


title: On the $b-$ Quark Kinetic Energy in the $\Lambda_b$

abstract:
  We consider the problem of determining the matrix element of the heavy quark
kinetic energy operator between $\Lambda_b$ baryonic states by three point
function QCD sum rules in the Heavy Quark Effective Theory. We discuss the main
features and the uncertainties associated to such an approach. Numerically, we
find the result: ${\langle{\cal K}\rangle}_{\Lambda_b} = - (0.6 \pm 0.1) \;
GeV^2$. Within the uncertainty of the method, such result indicates a value of
the heavy quark kinetic energy in the baryon similar in size to that in the
meson.


title: Supersymmetry and Grand Unification

abstract:
  Supersymmetry and Grand Unification are the two most promising directions for
physics beyond the Standard Model. They receive indirect experimental support
from the apparent lightness of the Higgs boson, the values of the gauge
couplings measured at LEP and elsewhere, and the persistent solar neutrino
deficit. Phenomenological constraints and theoretical models constrain
predictions in interesting ways. All these ideas may be embedded in string
theory, which is shown by newly-discovered dualities to possess
previously-unsuspected richness and simplicity.


title: Dispersive Approach to Power-Behaved Contributions in QCD Hard Processes

abstract:
  We consider power-behaved contributions to hard processes in QCD arising from
non-perturbative effects at low scales which can be described by introducing
the notion of an infrared-finite effective coupling. Our method is based on a
dispersive treatment which embodies running coupling effects in all orders. The
resulting power behaviour is consistent with expectations based on the operator
product expansion, but our approach is more widely applicable. The
dispersively-generated power contributions to different observables are given
by (log-)moment integrals of a universal low-scale effective coupling, with
process-dependent powers and coefficients. We analyse a wide variety of
quark-dominated processes and observables, and show how the power contributions
are specified in lowest order by the behaviour of one-loop Feynman diagrams
containing a gluon of small virtual mass. We discuss both collinear safe
observables (such as the e+e- total cross section and \tau hadronic width, DIS
sum rules, e+e- event shape variables and the Drell-Yan K-factor) and collinear
divergent quantities (such as DIS structure functions, e+e- fragmentation
functions and the Drell-Yan cross section).


title: Mass Degeneracy of the Higgsinos

abstract:
  The search for charginos and neutralinos at LEP2 can become problematic if
these particles are almost mass degenerate with the lightest neutralino.
Unfortunately this is the case in the region where these particles are
higgsino-like. We show that, in this region, radiative corrections to the
higgsino mass splittings can be as large as the tree-level values, if the
mixing between the two stop states is large. We also show that the degree of
degeneracy of the higgsinos substantially increases if a large phase is present
in the higgsino mass term $\mu$.


title: Chiral Anomaly and $\gamma 3\pi$

abstract:
  Measurement of the $\gamma 3\pi$ process has revealed a possible conflict
with what should be a solid prediction generated by the chiral anomaly. We show
that inclusion of appropirate energy-momentum dependence in the matrix element
reduces the discrepancy.


title: Is the standard Higgs scalar elementary?

abstract:
  In the standard electroweak model, the measured top quark mass requires a
sizeable Yukawa coupling to the fundamental scalar. This large coupling alone
might induce a dynamical breaking of the electroweak symmetry as well as
non-perturbative effects. If such is the case, even a standard Higgs scalar as
light as 80 GeV should have a non-negligible $t \bar{t}$ component induced by
the top condensate.


title: Perturbative Contributions to the Electroweak Interface Tension

abstract:
  The main perturbative contribution to the free energy of an electroweak
interface is due to the effective potential and the tree level kinetic term.
The derivative corrections are investigated with one-loop perturbation theory.
The action is treated in derivative, in heat kernel, and in a multi local
expansion. The massive contributions turn out to be well described by the
Z-factor. The massless mode, plagued by infrared problems, is numerically less
important. Its perturbatively reliable part can by calculated in derivative
expansion as well. A self consistent way to include the Z-factor in the formula
for the interface tension is presented.


title:
Extraction of $\alpha$ From the CP Asymmetry in B^0/\bar B^0 --> pi+ pi-
  Decays

abstract:
  The influence of strong and electroweak penguin amplitudes in $B/ \bar B
\rightarrow \pi^+\pi^-$ is investigated in connection with the determination of
the unitarity triangle angle $\alpha$ of the CKM matrix. A relation between the
observable asymmetry, the angle $\alpha$, and the penguin amplitude is
established. A model calculation of the penguin amplitude shows that the CP
asymmetry in $B^{0}\rightarrow \pi^{+}\pi^{-}$ decays is only mildly influenced
by the penguin amplitudes. Experimental limits on pure penguin and penguin
dominated processes are consistent with the model. This information also
suggests in a rather model independent way that penguin amplitudes will not be
a serious complicating factor in the determination of $\alpha$ from the
$\pi^{+}\pi^{-}$ time dependent asymmetry.


title:
Singular Classical Solutions and Tree Multiparticle Cross Sections in
  Scalar Theories

abstract:
  We consider the features of multiparticle tree cross sections in scalar
theories in the framework of a semiclassical approach. These cross sections at
large multiplicities have exponential form, and the properties of the exponent
in different regimes are discussed.


title:
Analytic Calculation of Prompt Photon plus Associated Heavy Flavor at
  Next-to-Leading Order in QCD

abstract:
  Contributions through second order, $O(\alpha ^2_s)$, in perturbative quantum
chromodynamics are calculated analytically for inclusive associated production
of a prompt photon and a charm quark at large values of transverse momentum in
high energy hadron-hadron collisions. Seven partonic subprocesses contribute at
order $\alpha^2_s$. We find important corrections to the lowest order,
$O(\alpha_s)$, subprocess $c g \rightarrow \gamma c$. We demonstrate to what
extent data from $p +\bar{p}\rightarrow \gamma + c + X$ may serve to measure
the charm quark density in the nucleon.


title: Small-Angle Electron-Positron Scattering with a Per Mille Accuracy

abstract:
  The elastic and inelastic high--energy small--angle electron--positron
scattering is considered. All radiative corrections to the cross--section with
the relative accuracy $\delta\sigma/ \sigma = 0.1 \% $ are explicitly taken
into account. According to the generalized eikonal representation for the
elastic amplitude, in higher orders only diagrams with one exchanged photon may
be considered. Single photon emission with radiative corrections and
next--to--leading two--photon and pair production diagrams are evaluated,
together with leading three--loop corrections. All contributions have been
calculated analytically. We integrate the calculated distributions over typical
for LEP~1 experiments intervals of angles and energies. To the leading
approximation, the results are shown to be described in terms of kernels of
electron structure functions. Some numerical results are presented.
  PACS numbers 12.15.Lk, 12.20.--m, 12.20.Ds, 13.40.--f


title: Radiative Electroweak Breaking with Pseudogoldstone Higgs Doublets

abstract:
  We consider a realistic example of supersymmetric grand unification based on
$SU(3)_c \times SU(3)_L \times SU(3)_R$ in which the electroweak (EW) higgs
doublets are `light' as a consequence of the `pseudogoldstone' mechanism. We
discuss radiative EW breaking in this model, exploring in particular the
`small' (order unity) and `large' $(\approx m_t/m_b)$ $\tan \beta$ regions by
studying the variations of $r (\equiv \sqrt{\mu^2_{1,2}/\mu^2_3})$, where
$\mu^2_{1,2,3}$ are the well known MSSM parameters evaluated at the GUT scale.
For $r$ sufficiently close to unity the quantity $\tan \beta$ can be of order
unity, but the converse is not always true.


title: Z' Reservation at LEP2

abstract:
  We consider the possibility that one extra $Z\equiv Z'$ exists with arbitrary
mass and fermion couplings that do not violate (charged) lepton universality.
We show that, in such a situation, a functional relationship is generated
between the \underline{deviations} from the SM values of three leptonic
observables of two-fermion production at future $e^+e^-$ colliders that is
completely independent of the values of the $Z'$ mass and couplings. This
selects a certain region in the 3-d space of the deviations that is
\underline{characteristic} of the model ($Z'$ "reservation"). As a specific and
relevant example, we show the picture that would emerge at LEP2 under realistic
experimental conditions.


title: Correlation between Instantons and QCD-monopoles in the Abelian Gauge

abstract:
  The correlation between instantons and QCD-monopoles is studied both in the
lattice gauge theory and in the continuum theory. From a simple topological
consideration, instantons are expected to live only around the QCD-monopole
trajectory in the abelian gauge. First, the instanton solution is analytically
studied in the Polyakov-like gauge, where $A_4(x)$ is diagonalized. The world
line of the QCD-monopole is found to be penetrate the center of each instanton
inevitably. For the single-instanton solution, the QCD-monopole trajectory
becomes a simple straight line. On the other hand, in the multi-instanton
system, the QCD-monopole trajectory often has complicated topology including a
loop or a folded structure, and is unstable against a small fluctuation of the
location and the size of instantons. We also study the thermal instanton system
in the Polyakov-like gauge. At the high-temperature limit, the monopole
trajectory becomes straight lines in the temporal direction. The topology of
the QCD-monopole trajectory is drastically changed at a high temperature.
Second, the correlation between instantons and QCD-monopoles is studied in the
maximally abelian (MA) gauge and/or the Polyakov gauge using the SU(2) lattice
with $16^4$. The abelian link variable $u_\mu (s)$ is decomposed into the
singular (monopole-dominating) part $u_\mu ^{Ds}(s)$ and the regular
(photon-dominating) part $u_\mu ^{Ph}(s)$. The instanton numbers, $Q({\rm Ds})$
and $Q({\rm Ph})$, are measured using the SU(2) variables, $U_\mu ^{Ds}(s)$ and
$U_\mu ^{Ph}(s)$, which are reconstructed by multiplying the off-diagonal
matter factor to $u_\mu ^{Ds}(s)$ and $u_\mu ^{Ph}(s)$, respectively. A strong
correlation is found between $Q({\rm Ds})$ in the singular part and the
ordinary topological charge $Q({\rm SU(2)})$ even after the Cabibbo-Marinari


title:
Heavy quarkonia mass-splittings in QCD: test of the $1/m$-expansion and
  estimates of $<\alpha_s G^2>$ and $\alpha_s$

abstract:
  New double ratios of exponential moments of different two-point functions,
which are less sensitive to the heavy quark mass and to the continuum effects
than the commonly used ratio of moments, are presented for a more refined
analysis of the mass-splittings between the different heavy quarkonia states.
We show that at the $c$ and $b$ quark mass scales the $1/m$-expansion does not
converge for these quarkonia channels, while a connection of our mass and width
formulae, with the potential model ones is done. Using the present value of the
QCD coupling $\alpha_s$, we deduce the value: $<\alpha_s G^2> = (7.5\pm
2.5)\times 10^{-2}$ GeV$^4$ of the gluon condensate from $M_\psi - M_{\eta_c}$
and $M_{\chi_b} - M_\Upsilon$, which we compare with the ones from different
fits of the heavy and light quark channels. We also find that
$M_{\chi_c(P^1_1)} - M_{\chi_c(P^3_1)}$ is gouverned by the radiative
corrections and gives $\alpha_s$(1.3 GeV) = 0.64$^{+0.36}_{-0.18}$ for 4
flavours, implying $\alpha_s(M_Z) = 0.127\pm 0.011$. Our predictions for the
splittings of different heavy quarkonia states are summarized in Table 2,
where, in particular, we find $M_{\Upsilon}-M_{\eta_b}\approx 63^{-29}_{+51}$
MeV implying the possible observation of the $\eta_b$ in the
$\Upsilon$-radiative decay.


title: Possible tests for sterile neutrinos

abstract:
  It is shown that the future SNO and Super-Kamiokande experiments, in which
high energy $^8\mathrm{B}$ neutrinos will be detected through the observation
of CC, NC and $\nu$--$e$ elastic scattering processes, could allow to reveal in
a model independent way the presence of sterile neutrinos in the flux of solar
neutrinos on the earth.


title:
Electromagnetic Properties of the SU(3) Octet Baryons in the
  semibosonized Nambu--Jona-Lasinio Model

abstract:
  The electromagnetic properties of the SU(3) octet baryons are investigated in
the semibosonized SU(3) Nambu--Jona-Lasinio model.The rotational $1/N_c$ and
strange quark mass corrections in linear order are taken into account. It turns
out that the model is in good agreement with the experimental data.


title: Nucleon Tensor Charges in the Chiral Quark--Soliton Model

abstract:
  We investigate the singlet $g_T^{(0)}$ and isovector $g_T^{(3)}$ tensor
charges of the nucleon, which are deeply related to the first moment of the
leading twist transversity quark distribution $h_1(x)$, in the chiral
quark-soliton model. With rotational $O(1/N_c) $ corrections taken into
account, we obtain $g_T^{(0)}=0.69$ and $g_T^{(3)}=1.45$ at a low normalization
poin of several hundreds MeV.
  Within the same approximation and parameters the model yields
$g_A^{(0)}=0.36$, $g_A^{(3)}=1.21$ for axial charges and correct
octet--decuplet mass splitting. We show how the chiral quark-soliton model
interpolates between the nonrelativistic quark model and the Skyrme model.


title: Bound states of massless fermions as a source for new physics

abstract:
  The contribution of interactions at short and large distances to particle
masses is discussed in the framework of the standard model.


title: Neutrino oscillations with three-generation mixings and mass hierarchy

abstract:
  We have analyzed the results of reactor and accelerator neutrino oscillation
experiments in a model with mixing of three neutrino fields and a neutrino mass
hierarchy. It is shown that $ \nu_\mu \leftrightarrows \nu_e $ oscillations
with $ 0.6 \le \Delta m^2 \le 100 \, \mathrm{eV}^2 $ and amplitude larger than
$ 2 \times 10^{-3} $ are not compatible with the existing limits on neutrino
oscillations if the non-diagonal elements of the mixing matrix are small. Thus,
if the excess of positron events recently observed in the LSND experiment is
due to $ \bar\nu_\mu \to \bar\nu_e $ oscillations, the mixing in the lepton
sector is basically different from the CKM mixing of quarks.


title: Disoriented Sleptons

abstract:
  We discuss some fundamental concerns regarding the recent proposal of
Dimopoulos and Giudice for dynamically aligning the soft masses of the
sfermions in the minimal supersymmetric standard model (MSSM) with the
corresponding fermion masses to suppress flavor changing neutral currents. We
show that the phenomenologically-favored presence of right-handed neutrinos in
the theory, even if only at very high scales, generically disaligns the slepton
mass matrices. Further suppression is then needed to meet the current upper
bound on the rate for $\mu \to e\gamma$. Planned improvements in the search for
$\mu \to e\gamma$ should easily detect this rare mode. (With improved
sensitivity $\mu\to 3e$ may also be seen.) By measuring the helicity of the
amplitude for $\mu \to e\gamma$ such experiments could distinguish between
unified and non-unified models at very high energies; by inserting the various
MSSM parameters as they become available, the mixing in the leptonic Yukawa
couplings can be extracted; and by combining the results with those of various
neutrino experiments some information about the right-handed neutrino Majorana
matrices can also be gained.


title: Higgs-strahlung and $WW$ fusion in $e^+e^-$ collisions

abstract:
  Higgs-strahlung $e^+e^-\to ZH$ and $WW$ fusion $e^+e^-\to\bar\nu_e\nu_e H$
are the most important mechanisms for the production of Higgs bosons in
$e^+e^-$ collisions at LEP2 and future $e^+e^-$ linear colliders. We have
calculated the cross sections and energy/angular distributions of the Higgs
boson for these production mechanisms. When the $Z$ boson decays into
(electron-)neutrinos, the two production amplitudes interfere. In the
cross-over region between the two mechanisms the interference term is positive
and of the same size as the individual cross sections, thus enhancing the
production rate.


title: A New Estimate of $\varepsilon '/\varepsilon$

abstract:
  We discuss direct $CP$ violation in the standard model by giving a new
estimate of $\varepsilon'/\varepsilon$ in kaon decays. Our analysis is based on
the evaluation of the hadronic matrix elements of the \mbox{$\Delta S =1$}
effective quark lagrangian by means of the chiral quark model, with the
inclusion of meson one-loop renormalization and NLO Wilson coefficients. Our
estimate is fully consistent with the $\Delta I =1/2$ selection rule in $K\to
\pi\pi$ decays which is well reproduced within the same framework. By varying
all parameters in the allowed ranges and, in particular, taking the quark
condensate---which is the major source of uncertainty---between $(-200\ {\rm
MeV})^3$ and $(-280\ {\rm MeV})^3$ we find $$ -5.0 \times 10^{-3}\
<\varepsilon'/\varepsilon <\ 1.4 \times 10^{-3}\ .$$ Assuming for the quark
condensate the improved PCAC result \mbox{$\vev{\bar qq} = -(221\: \pm 17\ {\rm
MeV})^3$} and fixing $\Lambda_{\rm QCD}^{(4)}$ to its central value, we find
the more restrictive prediction $$\varepsilon '/\varepsilon = ( 4 \pm 5 )
\,\times \,10^{-4}\ , $$ where the central value is defined as the average over
the allowed values of Im $\lambda_t$ in the first and second quadrants. In
these estimates the relevant mixing parameter Im $\lambda_t$ is
self-consistently obtained from $\varepsilon$ and we take $m_t^{\rm pole} = 180
\pm 12$ GeV. Our result is, to a very good approximation, renormalization-scale
and $\gamma_5$-scheme independent.


title: Nonfactorization in B and D decays

abstract:
  We discuss the role of nonfactorized contributions in $B \rightarrow \psi +
{K}^{*} $ and charmed meson decays. We demonstrate, using $ {D}^{+}_{S}
\rightarrow \phi \pi$ as a model, how nonfactorization, annihilation and final
state interactions can be built into effective and unitarized $ {a}_{1} $ and $
{a}_{2} $.


title: Strong WW scattering in unitary gauge

abstract:
  A method to embed models of strong $WW$ scattering in unitary gauge
amplitudes is presented that eliminates the need for the effective $W$
approximation (EWA) in the computation of cross sections at high energy
colliders.The cross sections obtained from the U-gauge amplitudes include the
distributions of the final state fermions in $ff \rightarrow ffWW$, which
cannot be obtained from the EWA. Since the U-gauge method preserves the
interference of the signal and the gauge sector background amplitudes, which is
neglected in the EWA, it is more accurate, especially if the latter is
comparable to or bigger than the signal, as occurs for instance at small angles
because of Coulomb singularities. The method is illustrated for on-shell
$W^+W^+ \rightarrow W^+W^+$ scattering and for $qq \rightarrow qqW^+W^+$.