title:
Transverse Momentum and Sudakov Effects in Exclusive QCD Processes:
  gamma* gamma pi0 Form Factor

abstract:
  We analyze effects due to transverse degrees of freedom in QCD calculations
of the fundamental hard exclusive amplitude of $\gamma^*\gamma \to \pi^0$
transition. A detailed discussion is given of the relation between the modified
factorization approach (MFA) of Sterman et al. and standard factorization
(SFA). Working in Feynman gauge, we construct basic building blocks of MFA from
the one-loop coefficient function of the SFA, demonstrating that Sudakov
effects are distinctly different from higher-twist corrections. We show also
that the handbag-type diagram, contrary to naive expectations, does not contain
an infinite chain of $(M^2/Q^2)^n$ corrections: they come only from diagrams
with transverse gluons emitted from the hard propagator. A simpler picture
emerges within the QCD sum rule approach: the sum over soft $\bar q G ... G q$
Fock components is dual to $\bar qq$ states generated by the local axial
current. We combine the results based on QCD sum rules with pQCD radiative
corrections and observe that the gap between our curves for the asymptotic and
CZ distribution amplitudes is sufficiently large for an experimental
discrimination between them.


title: Quark condensate in a magnetic field

abstract:
  We study the dependence of quark condensate $\Sigma$ on an external magnetic
field. For weak fields, it rises linearly with the field. Pion mass and residue
are also shifted so that the Gell-Mann - Oakes - Renner relation is satisfied.
In the strong field region, $\Sigma(H) \propto (eH)^{3/2}$.


title: The Thomas-Fermi approximation for gauge theories

abstract:
  An effective field approximation, similar to the atomic Thomas-Fermi
approach, is proposed for studying non-Abelian gauge theories which includes
finite-volume effects. As applications of the formalism the equation of state
for an SU(2) gauge theory with massless fermions is obtained. The extensions to
realistic situations are briefly discussed.


title: Higgs Physics at a Muon Collider

abstract:
  A brief review of muon-collider $s$-channel Higgs physics in the Standard
Model and its minimal supersymmetric extension is presented.


title: Physics at LHC

abstract:
  We review the physics to be investigated at LHC. We also describe the main
parameters of CMS and ATLAS detectors.


title: Strange dibaryons in the Skyrme model

abstract:
  The phenomenological consequences of the existence of different local minima
in SU(3) configuration space of B=2 skyrmions are discussed.


title:
Custodial Symmetry, Flavor Physics, and the Triviality Bound on the
  Higgs Mass

abstract:
  The triviality of the scalar sector of the standard one-doublet Higgs model
implies that this model is only an effective low-energy theory valid below some
cut-off scale Lambda. We show that the experimental constraint on the amount of
custodial symmetry violation implies that the scale Lambda must be greater than
of order 7.5 TeV. The underlying high-energy theory must also include flavor
dynamics at a scale of order Lambda or greater in order to give rise to the
different Yukawa couplings of the Higgs to ordinary fermions. This flavor
dynamics will generically produce flavor-changing neutral currents. We show
that the experimental constraints on the neutral D-meson mass difference imply
that Lambda must be greater than of order 21 TeV. For theories defined about
the infrared-stable Gaussian fixed-point, we estimate that this lower bound on
Lambda yields an upper bound of approximately 460 GeV on the Higgs boson's
mass, independent of the regulator chosen to define the theory. We also show
that some regulator schemes, such as higher-derivative regulators, used to
define the theory about a different fixed-point are particularly dangerous
because an infinite number of custodial-isospin-violating operators become
relevant.


title:
Predictions for Spectral Distortions, Event Rates and D-N Asymmetries
  for the Super - Kamiokande Detector

abstract:
  Day - Night asymmetries and electronic spectra distortions for the Super -
Kamiokande detector are computed for the transition nu_e -> nu_mu(tau) and for
a set of neutrino parameters. The results show the possibility to enhance up to
a factor six the Day - Night asymmetry selecting neutrino events induced by
neutrinos which cross the Earth core. This should increase the sensitivity of
the Super - Kamiokande detector to the Day - Night effect for sin^2(2 theta_v)
< 0.01 and 5 x 10^-6 eV^2 < Delta m^2 < 10^-5 eV^2.


title:
New high order relations between physical observables in perturbative
  QCD

abstract:
  We exploit the fact that within massless perturbative QCD the same Green's
function determines the hadronic contribution to the $\tau$ decay width and the
moments of the $e^+e^-$ cross section. This allows one to obtain relations
between physical observables in the two processes up to an unprecedented high
order of perturbative QCD. A precision measurement of the $\tau$ decay width
allows one then to predict the first few moments of the spectral density in
$e^+e^-$ annihilations integrated up to $s\sim m_\tau^2$ with high accuracy.
The proposed tests are in reach of present experimental capabilities.


title: Hybrid Inflation in Supergravity

abstract:
  We propose a simple realization of hybrid inflation in supergravity, which
does not require any unnaturally small parameters. Inflation in this scenario
is relatively short, and inflationary density perturbations fall down on large
scales, which corresponds to a blue spectrum with n > 1. Superheavy strings
which are formed after inflation in this scenario produce density perturbations
of comparable magnitude. In this mixed perturbation (MP) model one may have
microwave anisotropy produced by strings and galaxy formation due to
inflationary perturbations.


title: Photon-neutrino interactions

abstract:
  The cross sections for the processes \gamma \nu --> \gamma\gamma \nu,
\gamma\gamma -->\gamma\nu\bar{\nu} and \nu\bar{\nu} -->\gamma\gamma\gamma are
calculated with the aid of an effective Lagrangian derived from the Standard
model. These cross sections are shown to be much larger than the elastic cross
section \sigma(\gamma\nu --> \gamma\nu) for photon energies $\omega > 1$ keV.
Possible astrophysical implications are discussed.


title:
Signals for gauge-mediated supersymmetry breaking models at the CERN
  LEP2 collider

abstract:
  We consider a general class of models with gauge-mediated supersymmetry
breaking in which the gravitino is the lightest supersymmetric particle.
Several qualitatively different scenarios arise for the phenomenology of such
models, depending on which superpartner(s) decay dominantly to the gravitino.
At LEP2, neutralino pair production and slepton pair production can lead to a
variety of promising discovery signals, which we systematically study. We
investigate the impact of backgrounds for these signals and show how they can
be reduced, and outline the effects of model parameter variations on the
discovery potential.


title: The baryogenesis window in the MSSM

abstract:
  Thermal two-loop QCD corrections associated with light stops have a dramatic
effect on the strength of the MSSM electroweak phase transition, making it more
strongly first order as required for the viability of electroweak baryogenesis.
We perform a perturbative analysis of the transition strength in this model,
including these important contributions, extending previous work to arbitrary
values of the pseudoscalar Higgs boson mass, m_A. We find a strong enough
transition in a region with 2< tan beta < 4 and m_A > 120 GeV, a light Higgs
boson with nearly standard couplings, and mass below 85 GeV within the reach of
LEP II, and one stop not much heavier than the top quark. In addition, we give
a qualitative discussion of the parameter space dependence of the transition
strength and comment on the possibility that the transition turns to a
crossover for sufficiently large Higgs masses.


title:
Model independent results for $B\to D_1(2420)\ell\bar\nu$ and $B\to
  D_2^*(2460)\ell\bar\nu$ at order $\Lambda_{QCD}/m_{c,b}$

abstract:
  Exclusive semileptonic B decays into $D_1$ and $D_2^*$ mesons are
investigated including order $\Lambda_{QCD}/m_{c,b}$ corrections using the
heavy quark effective theory. At zero recoil, the $\Lambda_{QCD}/m_{c,b}$
corrections can be written in terms of the leading Isgur-Wise function for
these transitions, $\tau$, and known meson mass splittings. We obtain an almost
model independent prediction for the shape of the spectrum near zero recoil,
including order $\Lambda_{QCD}/m_{c,b}$ corrections. We determine $\tau(1)$
from the measured $B\to D_1\ell\bar\nu$ branching ratio. Implications for B
decay sum rules are discussed.


title: Neutrinos with Magnetic Moment: Depolarization Rate in Plasma

abstract:
  Neutrinos with a magnetic moment $\mu$ change their helicity when interacting
with an electromagnetic field. Various aspects of this effect have been
described as spin precession, spin-flip scattering, and magnetic Cherenkov
radiation. These perspectives are unified in an expression for the
$\nu_L\to\nu_R$ transition rate which involves the correlators of the
electromagnetic field distribution. Our general formula corrects a previous
result and generalizes it to the case where the fields cannot be viewed as
classical and where the momentum transfers need not be small. We evaluate our
result explicitly for a relativistic QED plasma and determine the
depolarization rate to leading order in the fine structure constant. Assuming
that big-bang nucleosynthesis constraints do not allow a right-handed neutrino
in equilibrium we derive the limit $\mu<6.2\EE{-11}\mu_B$ on the neutrino
magnetic moment. Bounds on $\mu$ from a possible large scale magnetic fields
are found to be more stringent even for very weak fields


title: Heavy neutrino mixing and single production at Linear Collider

abstract:
  We study the single production of heavy neutrinos via the processes $e^-e^+
\to \nu N$ and $e^-\gamma \to W^- N$ at future linear colliders. As a base of
our considerations we take a wide class of models, both with vanishing and
non-vanishing left-handed Majorana neutrino mass matrix $m_L$. We perform a
model independent analyses of the existing experimental data and find
connections between the characteristic of heavy neutrinos (masses, mixings, CP
eigenvalues) and the $m_L$ parameters. We show that with the present
experimental constraints heavy neutrino masses almost up to the collision
energy can be tested in the future experiments.


title: CP Violation in radiative Z Decays

abstract:
  We propose to test the CP symmetry in the reactions Z -> mu+ mu- gamma and Z
-> tau+ tau- gamma. The experimental analysis of angular correlations allows to
determine a set of effective couplings: the electric and weak dipole moments of
the muon and the tau lepton, and in particular chirality conserving 4-particle
couplings, all of which can be induced by CP--violation in renormalizable
theories of electroweak interactions beyond the Standard Model. We update an
indirect bound on the weak dipole moment of the muon.


title: A Second Look at Masses and Mixings of Quarks and Leptons

abstract:
  The masses of quarks and leptons in units of $m_t$ are expressed in powers of
$\sigma=\sqrt{m_c/m_t}$. The regularities found suggest specific mass matrices.
They reproduce all masses and mixings in striking agreement with observation. A
90 degree relative phase angle between the off-diagonal elements of up and down
quark matrices leads to a maximum magnitude for CP-violation and, for the phase
angle $\gamma$ of the unitary triangle, to $\gamma\simeq 90^o$.


title:
The reaction $\pi N \to \pi \pi N$ above threshold in chiral
  perturbation theory

abstract:
  Single pion production off nucleons is studied in the framework of
relativistic baryon chiral perturbation theory at tree level with the inclusion
of the terms from the dimension two effective pion-nucleon Lagrangian. The five
appearing low-energy constants are fixed from pion-nucleon scattering data.
Despite the simplicity of the approach, most of the existing data for total and
differential cross sections as well as for the angular correlation functions
for incoming pion kinetic energies up to 400 MeV can be satisfactorily
described.


title: Solitons Bound to Heavy Mesons

abstract:
  We improve the bound state approach of the Skyrme model applied to the heavy
baryons by adopting a static heavy meson picture where the soliton moves around
the fixed heavy meson. This allows to take into account the center of mass
corrections in a more consistent way. The bound state masses so obtained are
comparable to the experimentally observed $\Lambda_c$ and $\Lambda_c^*$ masses.
A loosely bound state of a soliton with an antiflavored heavy meson is found,
which leaves a possibility of the nonstrange pentaquark baryon(s).


title:
Improved Determination of the Hadronic Contribution to the Muon (g-2)
  and to alpha(M_Z**2) Using new Data from Hadronic Tau Decays

abstract:
  We have reevaluated the hadronic contribution to the anomalous magnetic
moment of the muon (g-2) and to the running of the QED fine structure constant
alpha(s) at s=M_Z**2. We incorporated new data from hadronic tau decays,
recently published by the ALEPH Collaboration. In addition, compared to
previous analyses, we use more extensive e+e- annihilation data sets. The
integration over the total hadronic cross section is performed using
experimental data up to 40 GeV and results from perturbative QCD above 40 GeV.
The improvement from tau data concerns mainly the pion form factor, where the
uncertainty in the corresponding integral could be reduced by more than a
factor of two. We obtain for the lowest order hadronic vacuum polarization
graph a_mu(had) = (695.0 +/- 15.0) x 10^{-10} and delta(alpha(M_Z**2))(had) =
(280.9 +/- 6.3) x 10^{-4} using e+e- data only. The corresponding results for
combined e+e- and tau data are a_mu(had) = (701.1 +/- 9.4) x 10^{-10} and
delta(alpha(M_Z**2))(had) = (281.7 +/- 6.2) x 10^{-4}, where the latter is
calculated using the contribution from the five lightest quarks.


title:
Probing the Flavor-Changing tc vertex via Tree-Level Processes: e+e- ->
  t bar-c nu_e bar-nu_e, t bar-c e+ e- and t -> c W+ W-

abstract:
  The reactions e+e- -> t bar-c nu_e bar-nu_e, t bar-c e+ e- are very sensitive
probes of the flavor-changing-scalar couplings which can occur in a model with
one extra Higgs doublet. At the Next Linear Collider, with a center of mass
energy of sqrt{s}=0.5--2 TeV, several hundreds and up to thousands of such
events may be produced if the mass of the light neutral Higgs is a few hundred
GeV. We also briefly comment on the decays t -> c W+ W-, t -> c Z Z. All of
these reactions are severely suppressed in the Standard Model


title: No Strings Attached: Potential vs. Interaction Energy In QCD

abstract:
  In infrared-stable fixed-point field theories, the interaction energy of a
test particle is proportional to the non-relativistic (heavy source)
coordinate-space potential derived from the field strength produced by that
source. This is no longer true in ultraviolet-stable fixed-point field theories
(UVSFPFT) as they may not have a finite infrared fixed point. This leads to the
possibility that UVSFPFTs may have quite conventional field strength
distributions despite the unusual spatial dependence expected for the
interaction energy.


title: Heavy Flavor Weak Decays

abstract:
  Weak decays of heavy flavor hadrons play a special role in our understanding
of physics of the Standard Model and beyond. The measured quantities, however,
result from a complicated interplay of weak and strong interactions. Weak
leptonic and semileptonic decays are reasonably well understood, whereas weak
hadronic decays present challenges to theory. In this talk, we review the
present status of exclusive weak decays of charm and bottom hadrons.


title:
Effects of QCD Resummation on $W^+h$ and $t\bar b$ Production at the
  Tevatron

abstract:
  The resummation of multiple soft gluon emission affects the production rate
and kinematic distributions of $W^+h$ (where h is a Higgs boson) and $t \bar b$
pairs at the Tevatron with $\sqrt{s}=2$ TeV. Using the Collins-Soper-Sterman
resummation formalism, the production rate is enhanced over the
next-to-leading-order (NLO) prediction by 2-3% for the $W^+h$ process, for
Higgs boson masses between 80-120 GeV, and over 3% for the $t\bar b$ process
for $m_t=175$ GeV. After resummation, the $t\bar b$ rate changes by 12-13% when
$m_t$ is varied by $\pm 5$ GeV. Various kinematic distributions are presented
for the individual final state particles and for the pair. The explicit
radiation of hard gluons in NLO QCD is included also for the $t\bar b$ final
state.


title: Diffusion and the BFKL Pomeron

abstract:
  We study the high energy behaviour of elastic scattering amplitudes within
the leading logarithm approximation. In particular, we cast the amplitude in a
form which allows us to study the internal dynamics of the BFKL Pomeron for
general momentum transfer. We demonstrate that the momentum transfer acts as an
effective infrared cut-off which ensures that the dominant contribution arises
from short distance physics.


title:
Estimations of Order alpha_s^3 and alpha_s^4 Corrections to
  Mass-Dependent Observables

abstract:
  A simple procedure to estimate O(alpha_s^3) and O(alpha_s^4) corrections to
mass-dependent observables is conjectured. The method is tested in a number of
cases where the O(alpha_s^3) contribution is exactly known, and reasonable
agreement is found.


title:
Implementation of Bose - Einstein interference effects in Monte Carlo
  generators

abstract:
  A practical method of calculating weights implementing the Bose - Einstein
interference effects is presented. The usefulness of the method is demonstrated
for the events generated by the JETSET/PYTHIA code to describe the UA1
proton-antiproton data at 630GeV. A good description of data is achieved with a
reasonable value of the Gaussian width of a two-particle weight factor, which
is the only free parameter in our calculations.


title:
Phenomenology of Forward Hadrons in DIS: Fracture Functions and its
  $Q^2$ Evolution

abstract:
  We analyse recent data on the production of forward neutrons in deep
inelastic scattering at HERA in the framework of a perturbative QCD description
for semi-inclusive processes, which includes fracture functions. Using a model
estimate for the non-perturbative piece of the fragmentation process, in fairly
good agreement with the available data, we analyse the $Q^2$ dependence of the
resulting fracture functions, which is driven by non-homogeneous evolution
equations. We also propose a measurement of the pion production cross section
in the target fragmentation region as a new test of perturbative QCD, which in
this case predicts also a different $Q^2$ evolution with respect to the one
given by the usual Altarelli-Parisi equations.


title: Spontaneous Chiral Symmetry Breaking Beyond BCS

abstract:
  At the BCS level of chiral symmetry breaking, the mass gap equation for
quark-antiquark condensation only uses the kernel of the Bethe-Salpeter
equation. We introduce coupled channels with ladder mesons in the mass gap
equation. Consistency is insured by the Ward Identity for axial currents, and
the $\pi$ remains a Goldstone boson in the chiral limit. We find that bare
mesons with confined quarks do not contribute to the mass gap equation, and
estimate that the contribution of full mesons may be large.


title: SUSY Higgs Boson Decays

abstract:
  I discuss the decay modes of the neutral and charged Higgs bosons in the
minimal supersymmetric extension of the Standard Model. Special emphasis will
be put on the the QCD corrections to the hadronic decay modes, the below
threshold -three body- decays and the decays into supersymmetric particles,
charginos, neutralinos and sfermions. A Fortran code calculating the various
Higgs decay branching ratios is then briefly presented. [Talk given at the
Ringberg Workshop The Higgs Puzzle, Ringberg Castle, Tegernsee, Germany,
December 8-13 1996; to appear in the proceedings.]


title: Radiative corrections in the MSSM Higgs sector

abstract:
  1-loop diagrammatic calculations of cross sections and decay widths of
neutral Higgs bosons in the minimal supersymmetric standard model are reviewed
and compared with compact expressions in the effective potential approximation.


title: Flattening the Inflaton's Potential with Quantum Corrections II

abstract:
  In a previous paper I showed that a classical scalar potential with $V''/V
\sim 1$ can be sufficiently flattened by quantum corrections to give rise to
slow-roll inflation. In this paper I give a hybrid inflation implementation of
that idea which can naturally produce a spectral index in the observationally
viable range even for $V^{1/4} \sim 10^{10}$ to $10^{11}$ GeV. Although any
observationally viable spectral index can be obtained, the model does predict a
distinctive spectral shape.


title:
Progress on Symmetry Breaking and Generational Mixing in
  Topcolor-Assisted Technicolor

abstract:
  Topcolor-assisted technicolor provides a dynamical explanation for
electroweak and flavor symmetry breaking and for the large mass of the top
quark without unnatural fine tuning. I briefly review the basics of
topcolor-assisted technicolor, including major constraints and a general
approach to satisfying them. The main challenge to topcolor-assisted
technicolor is to generate the observed mixing between heavy and light
generations while breaking the strong topcolor interactions near 1 TeV. I argue
that these phenomena, as well as electroweak symmetry breaking, are intimately
connected and I present a scenario for them based on nontrivial patterns of
technifermion condensation. I also exhibit a class of models realizing this
scenario.


title: Hyperfine Splitting of Low-Lying Heavy Baryons

abstract:
  We calculate the next-to-leading order contribution to the masses of the
heavy baryons in the bound state approach for baryons containing a heavy quark.
These $1/N_C$ corrections arise when states of good spin and isospin are
generated from the background soliton of the light meson fields. Our study is
motivated by the previously established result that light vector meson fields
are required for this soliton in order to reasonably describe the spectrum of
both the light and the heavy baryons. We note that the inclusion of light
vector mesons significantly improves the agreement of the predicted hyperfine
splitting with experiment. A number of aspects of this somewhat complicated
calculation are discussed in detail.


title:
Meeting the Constraint of Neutrino-Higgsino Mixing in Gravity Unified
  Theories

abstract:
  In Gravity Unified Theories all operators that are consistent with the local
gauge and discrete symmetries are expected to arise in the effective low-energy
theory. Given the absence of multiplets like 126 of SO(10) in string models,
and assuming that B-L is violated spontaneously to generate light neutrino
masses via a seesaw mechanism, it is observed that string theory solutions
generically face the problem of producing an excessive $\nu_L-{\tilde H}$
mixing mass at the GUT scale, which is some nineteen orders of magnitude larger
than the experimental bound of 1 MeV. The suppression of $\nu_L-{\tilde H}$
mixing, like proton longevity, thus provides one of the most severe constraints
on the validity of any string theory solution. We examine this problem in a
class of superstring derived models. We find a family of solutions within this
class for which the symmetries of the models and an allowed pattern of VEVs,
surprisingly, succeed in adequately suppressing the neutrino-Higgsino mixing
terms. At the same time they produce the terms required to generate small
neutrino masses via a seesaw mechanism.


title:
Semi-inclusive Lambda_c^+ Leptoproductions and Polarized Gluon
  Distributions

abstract:
  In order to extract the behavior and magnitude of the spin-dependent gluon
distribution, we propose a semi-inclusive $\Lambda_c^+$ production using
unpolarized lepton beams and polarized proton targets. The correlation between
the target proton spin and the spin of $\Lambda_c^+$ produced in the target
fragmentation region might be very effective for testing various models of
polarized gluons.


title: Ferromagnetism of Axion Domain Wall

abstract:
  We show that axion domain wall is ferromagnetic in the universe with
nonvanishing baryon number or lepton number. It is caused by protons and
electrons bounded to the domain wall with their spins aligned. These bound
states arise due to attractive potentials generated through pseudo-vector
couplings between the fermions and the axion. Using a model of hadronic axions
we predict existence of a primordial magnetic field with strength $10^{-13}$
Gauss at recombination.


title: Conformal Invariance and the exact solution of BFKL equations

abstract:
  The conformal invariance properties of the QCD Pomeron in the transverse
plane allow us to give an explicit analytical expression for the solution of
the BFKL equations both in the transverse coordinate and momentum spaces. This
result is obtained from the solution of the conformal eigenvectors in the mixed
representation in terms of two conformal blocks, each block being the product
of an holomorphic times an antiholomorphic function. This property is used to
give an exact expression for the QCD dipole multiplicities and dipole-dipole
cross-sections in the whole parameter space, proving the equivalence between
the BFKL and dipole representations of the QCD Pomeron.


title: Phenomenological implications of moduli-dominant SUSY breaking

abstract:
  We study moduli-dominated SUSY breaking within the framework of string
models. This type of SUSY breaking in general leads to non-universal soft
masses, i.e. soft scalar masses and gaugino masses. Further gauginos are
lighter than sfermions. This non-universality has phenomenologically important
implications. We investigate radiative electroweak symmetry breaking in the
mass spectrum derived from moduli-dominated SUSY breaking, where the lightest
chargino and neutralino are almost gauginos. Moreover, constraints from the
branching ratio of $b \to s \gamma$ and the relic abundance of the LSP are also
considered. The mass spectrum of moduli-dominated SUSY breaking is favorable to
the experimental bound of the $b \to s \gamma$ decay decreasing its branching
ratio. We obtain an upper bound for the gravitino mass from the cosmological
constraint.


title: Cosmic Ray and Neutrino Tests of Special Relativity

abstract:
  Searches for anisotropies due to Earth's motion relative to a preferred frame
-- modern versions of the Michelson-Morley experiment -- provide precise
verifications of special relativity. We describe other tests, independent of
this motion, that are or can become even more sensitive. The existence of
high-energy cosmic rays places strong constraints on Lorentz non-invariance.
Furthermore, if the maximum attainable speed of a particle depends on its
identity, then neutrinos, even if massless, may exhibit flavor oscillations.
Velocity differences far smaller than any previously probed can produce
characteristic effects at accelerators and solar neutrino experiments.


title: Do muons oscillate ?

abstract:
  We develop a theory of the EPR-like effects due to neutrino oscillations in
the $\pi \to \mu\nu$ decays. Its experimental implications are space-time
correlations of neutrino and muon when they are both detected, while the pion
decay point is not fixed. However, the more radical possibility of muon
oscillations in experiments where only muons are detected (as it has been
suggested in hep-ph/9509261), is ruled out. We start by discussing decays of
monochromatic pions, and point out a few ``paradoxes''. Then we consider pion
wave packets, solve the ``paradoxes'', and show that the formulas for $\mu nu$
correlations can be transformed into the usual expressions, describing neutrino
oscillations, as soon as the pion decay point is fixed.


title: The Symmetry and the Problem of Mass Generation

abstract:
  The mass problem in particle physics and its impact for other fields is
discussed. While the problem of the nuclear masses has been resolved within the
QCD framework, many parameters of the ``Standard Model'' are related to the
fermion sector. The origin of the fermion masses remains unresolved. We discuss
attempts to explain the observed hierarchical features of the mass spectrum by
a symmetry, relating the mass eigenvalues to the flavor mixing angles.


title:
A simple approach to describe hadron production rates in inelastic pp
  and p$\bar{p}$ collisions

abstract:
  We show that the production rates of light-flavoured mesons and baryons in
inelastic pp and p$\bar{p}$ collisions can be described by a simple approach
used to describe data obtained in $e^{+}e^{-}$ annihilation. Based on the idea
of string fragmentation, the approach describes the production rates of
light-flavoured mesons and baryons originating from fragmentation in terms of
the spin, the binding energy of the particle, and a strangeness suppression
factor. Apart from a normalization factor and the additional sea quark
contribution in inelastic pp and p$\bar{p}$ collisions, pp, p$\bar{p}$ and
$e^{+}e^{-}$ data at various centre-of-mass energies are described
simultaneously.


title: Twist-2 Light-Cone Pion Wave Function

abstract:
  We present an analysis of the existing constraints for the twist-2 light-cone
pion wave function. We find that existing information on the pion wave function
does not exclude the possibility that the pion wave function attains its
asymptotic form. New bounds on the parameters of the pion wave function are
presented.


title: Diffraction at HERA

abstract:
  Recent results on diffraction at HERA, as measured by the H1 and ZEUS
collaborations, are reviewed. Results on the photon-proton total hadronic cross
section, on vector meson production both at small and large photon virtuality
and on photon diffraction are presented. The experimental signature of
diffraction at HERA, as well as the selection methods used by the two
collaborations are explained.


title: Some Remarks On Gauge-Mediated Supersymmetry Breaking

abstract:
  We investigate the communication of supersymmetry breaking to the Standard
Model in theories of gauge mediated supersymmetry breaking with general weakly
coupled messenger sectors. We calculate the one loop gaugino and two loop soft
scalar masses for nonvanishing Str M^2 of the messenger sector. The soft scalar
masses are sensitive to physics at scales higher than the messenger scale, in
contrast to models with vanishing messenger supertrace. We discuss the
implications of this ultraviolet sensitivity in theories with renormalizable
and nonrenormalizable supersymmetry breaking sectors. We note that the standard
relation, in minimal gauge mediation, between soft scalar and gaugino masses is
altered in models with nonvanishing messenger supertrace.


title:
Rigorous pion-pion scattering lengths from threshold pi N --> pi pi N
  data

abstract:
  A new evaluation of the universal $\pi\pi$ scattering length relation is used
to extract the $\pi\pi$ $s$-wave scattering lengths from threshold pion
production data. Previous work has shown that the chiral perturbation series
relating threshold pion production to $\pi\pi$ scattering lengths appears to
converge well only for the isospin-2 case, giving $a_2 = -0.031\pm 0.007
m_\pi^{-1}$. A model-independent and data-insensitive universal curve then
implies $a_0 = 0.235\pm 0.03 m_\pi^{-1}$ for the isospin-0 scattering length.


title: Extracting the rho-omega mixing amplitude from the pion form-factor

abstract:
  We re-examine and extend a recent analysis which showed that the rho-omega
mixing amplitude cannot be unambiguously extracted from the pion
electromagnetic form-factor in a model independent way. In particular, we focus
on the argument that the extraction is sensitive to the presence of any
intrinsic omega_I -> 2pi coupling. Our extended analysis confirms the original
conclusion, with only minor, quantitative differences. The extracted mixing
amplitude is shown to be sensitive to both the intrinsic coupling omega_I ->
2pi and to the value assumed for the mass of the neutral rho meson.


title: The top quark mass and flavor mixing in a Seesaw model of Quark Masses

abstract:
  The top quark mass and the flavor mixing are studied in the context of a
Seesaw model of Quark Masses based on the gauge group $SU(2)_L \times SU(2)_R
\times U(1)$. Six isosinglet quarks are introduced to give rise to the mass
hierarchy of ordinary quarks. In this scheme, we reexamine a mechanism for the
generation of the top quark mass. It is shown that, in order to prevent the
Seesaw mechanism to act for the top quark, the mass parameter of its isosinglet
partner must be much smaller than the breaking scale of $SU(2)_R$. As a result
the fourth lightest up quark must have a mass of the order of the breaking
scale of $SU(2)_R$, and a large mixing between the right-handed top quark and
its singlet partner occurs. We also show that this mechanism is compatible with
the mass spectrum of light quarks and their flavor mixing.


title: Supersymmetry Breaking Without A Messenger Sector

abstract:
  We propose a simple gauge-mediated supersymmetry breaking model in which
suitable soft breaking masses are dynamically generated without relying on a
messenger sector. This model is constructed as an extention of the 3-2 model
and needs no fine-tuning of parameters. The dynamical supersymmetry breaking
sector contains non-renormalizable interactions and vector-like fields.
Non-renormalizable terms are characterized by the couplings of O(1) in units of
the Planck scale. The vacuum of this model conserves the color and electro-weak
symmetry.


title: Possibility of Chargino Search at LEP II

abstract:
  We study the potential of the LEP200 collider for chargino production and the
possibility of the determination of some fundamental SUSY parameters through
the relation with this study. Total cross sections for two basic signatures of
pair chargino production and for main backgrounds are calculated. The set of
kinematic cuts is proposed for the effective background suppression and
extraction of the signal. Calculations and the MC simulation performed give the
limits on chargino and neutralino masses that could be obtained at LEP200 with
$\sqrt s =$ 200 GeV.


title: Exclusive J/Psi and Psi'decays into baryon-antibaryon pairs

abstract:
  Within a perturbative approach we investigate decays of charmonium states
into baryon-antibaryon pairs. Using a recently proposed wave function for the
nucleon and suitable generalizations of it to the hyperons and decouplet
baryons, we obtain the decay widths for the baryon-antibaryon channels in
reasonable agreement with data. An important difference to previous work is the
use of the c-quark mass in the perturbative calculation instead of the
charmonium mass. As a consequence of this feature our approach possesses, the
J/Psi and the Psi' decay widths do not scale with a high power of the ratio of
their masses.


title: Partial-Wave Amplitudes and Resonances in pbar + p -> pi + pi

abstract:
  Partial wave amplitudes have been extracted from accurate data on pbar + p ->
pi + pi by a method which incorporates the theoretical constraints of
analyticity and crossing symmetry. The resulting solution gives a good fit to
the annihilation data and is also consistent with the wealth of information in
the crossed channel pi + N -> pi + N. The partial wave amplitudes show evidence
for resonances in all partial waves with J < 6, at least one of which, a J = 0+
state, (and possibly another with J = 1-) is unlikely to have a simple
quark-antiquark structure.


title: The Drell-Hearn-Gerasimov Sum-Rule in QCD

abstract:
  Photoproduction spin sum-rules offer a new window on the spin structure of
the nucleon that complements the information we can learn from polarised deep
inelastic scattering experiments. We review the theory and present status of
the Drell-Hearn-Gerasimov sum-rule in QCD, emphasising the possible relation
between the present ``discrepancy'' in this sum-rule and the nucleon's
strangeness magnetic moment. In the case of an elementary electron or photon
target (say at the NLC) the Drell-Hearn-Gerasimov sum-rule provides a test for
physics beyond the minimal Standard Model.


title: Rapidity Gap of Weakly Coupled Leptoquark Production in ep Collider

abstract:
  We show that the current bounds on the leptoquark couplings imply that if
leptoquarks are produced in e p collisions, a significant fraction of them
could form a leptoquark-quark bound state. The decay of the bound state has a
distinct event shape with rapidity gap. A possible application of this
observation in the leptoquark search at HERA is discussed.


title: False Vacuum Decay Induced by Particle Collisions

abstract:
  The semiclassical formalism for numerical calculation of the rate of
tunneling transitions induced by N particles with total energy E of order or
higher than the height of the barrier is developed. The formalism is applied to
the induced false vacuum decay in the massive four-dimensional $-\lambda\phi^4$
model. The decay rate, as a function of E and N, is calculated numerically in
the range $0.4\lsim E/E_{sph}\lsim 3.5$ and $0.25 \lsim N/N_{sph}\lsim 1.0$,
where $E_{sph}$ and $N_{sph}$ are the energy and the number of particles in the
analog of the sphaleron configuration. The results imply that the
``two-particle'' cross section of the false vacuum decay is exponentially
suppressed at least up to energies of order $10 E_{sph}$. At $E\sim E_{sph}$,
this exponential suppression is estimated as about 80% of the zero energy
suppression.


title: Unquenching the scalar glueball

abstract:
  Computations in the quenched approximation on the lattice predict the
lightest glueball to be a scalar in the 1.5-1.8 GeV region. Here we calculate
the dynamical effect the coupling to two pseudoscalars has on the mass, width
and decay pattern of such a scalar glueball. These hadronic interactions allow
mixing with the $q \overline q$ scalar nonet, which is largely fixed by the
well-established K_0^*(1430). This non-perturbative mixing means that, if the
pure gluestate has a width to two pseudoscalar channels of ~100 MeV as
predicted on the lattice, the resulting hadron has a width to these channels of
only ~30 MeV with a large eta-eta component. Experimental results need to be
reanalyzed in the light of these predictions to decide if either the f_0(1500)
or an f_0(1710) coincides with this dressed glueball.


title: Disorienting the Chiral Condensate at the QCD Phase Transition

abstract:
  I sketch how long wavelength modes of the pion field can be amplified during
the QCD phase transition. If nature had been kinder, and had made the pion mass
significantly less than the critical temperature for the transition, then this
phenomenon would have characterized the transition in thermal equilibrium.
Instead, these long wavelength oscillations of the orientation of the chiral
condensate can only arise out of equilibrium. There is a simple non-equilibrium
mechanism, plausibly operational during heavy ion collisions, which naturally
amplifies these oscillations. The characteristic signature of this phenomenon
is large fluctuations in the ratio of the number of neutral pions to the total
number of pions in regions of momentum space, that is in phase space in a
detector. Detection in a heavy ion collision would imply an out of equilbrium
chiral transition.


title: Can The Supersymmetric Flavor Problem Decouple?

abstract:
  It has been argued that the squarks and sleptons of the first and second
generations can be relatively heavy without destabilizing the weak scale,
thereby improving the situation with too-large flavor-changing neutral current
(FCNC) and CP violating processes. In theories where the soft supersymmetry
breaking parameters are generated at a high scale (such as the Planck scale),
we show that such a mass spectrum tends to drive the scalar top mass squared
$m_{\tilde{Q}_3}^2$ negative from two-loop renormalization group evolution.
Even ignoring CP violation and allowing $O(\lambda) \sim .22$ alignment, the
first two generation scalars must be heavier than 22 TeV to suppress FCNC. This
in turn requires the boundary condition on $m_{\tilde{Q}_3} > 4 TeV$ to avoid
negative $m_{\tilde{Q}_3}^2$ at the weak scale. Some of the models in the
literature employing the anomalous U(1) in string theory are excluded by our
analysis.


title: Recent Developments in Dark Matter Physics

abstract:
  After a short review of the arguments for the existence of Particle Dark
Matter in the Universe, I list the most plausible candidates provided by
particle physics, i.e. neutrinos, axions, and WIMPs. In each case I briefly
describe how to estimate the relic density, and discuss attempts at detecting
these particles. At the end I discuss my personal favorite, the lightest
supersymmetric particle, in a little more detail.


title: Are Isocurvature Fluctuations of the M-theory Axion Observable?

abstract:
  Banks and Dine have recently shown that the M theory naturally accommodates
the Peccei-Quinn axion. Since the decay constant $F_a$ of the axion is large as
$F_a \simeq 10^{15}-10^{16}$GeV, the halo axion is hardly detected in coming
axion-search experiments. However, we show that isocurvature fluctuations of
the M-theory axion produced at the inflationary epoch are most likely
detectable in future satellite experiments on anisotropies of the cosmic
microwave background radiation.


title: Gluons as Goldstone Bosons when Flavor Symmetry is Broken Spontaneously

abstract:
  The mechanism where flavor symmetry is broken spontaneously is discussed
within a scalar QCD model with effective three-meson couplings. For
sufficiently large coupling the model is unstable with respect to quantum loops
from mesonic vacuum polarization. It is argued that color and gluons naturally
can account for the Goldstone degrees of freedom expected when flavor symmetry
is spontaneously broken.


title: Remark on Z' limits at hadron colliders

abstract:
  Simple estimates for Z' exclusion limits and Z' model measurements in pp (p
bar p) collisions are derived. Due to properties of the structure functions,
the Z' exclusion limits depend only logarithmically on the Z' couplings to
fermions and on the integrated luminosity. The predicted scaling of Z'
exclusion limits and errors of Z' measurements with the c.m. energy and
luminosity allows an easy extrapolation of existing analyses to other
colliders.


title: Two-loop heavy top effects on precision observables and the Higgs mass

abstract:
  The electroweak corrections induced by a heavy top on the main precision
observables are now available up to O(g^4 mt^2/mw^2). The new results
significantly reduce the theoretical uncertainty and have a sizable impact on
the determination of sin^2theta_eff. We give precise predictions for mw and the
effective sine in different renormalization schemes, estimate their accuracy,
and discuss the implications for the indirect determination of M_H. From the
present data for sin^2theta_eff we obtain M_H = 127 +143 -71 GeV (or M_H < 430
GeV at 95% C.L.).


title: Neutrino Flavor Conversion in Random Magnetic Fields

abstract:
  If massive neutrinos possess magnetic moments, a magnetic field can cause a
spin flip. In the case of Dirac neutrinos the spin flip converts an active
neutrino into a sterile one and vice versa. By contrast, if neutrinos are
Majorana particles, a spin flip converts them to a neutrino of a different
flavor. We examine the behavior of neutrinos in a random magnetic field as it
occurs, for instance, in certain astronomical objects, such as an active
galactic nucleus. Both Dirac and Majorana neutrinos behave ergodically:
independently of their initial density matrix, they tend towards an
equipartition of the helicity states. As a result, about half of the Dirac
neutrinos produced becomes sterile. For Majorana neutrinos, there will be an
approximate equipartition of flavors, independently of the production
mechanism.


title: Lattice Chern-Simons Number Without Ultraviolet Problems

abstract:
  We develop a topological method of measuring Chern-Simons number change in
the real time evolution of classical lattice SU(2) and SU(2) Higgs theory. We
find that the Chern-Simons number diffusion rate per physical 4-volume is very
heavily suppressed in the broken phase, and that it decreases with lattice
spacing in pure Yang-Mills theory, although not as quickly as predicted by
Arnold, Son, and Yaffe.


title: FCNC Solutions to the Solar Neutrino Problem

abstract:
  We present the status of FCNC solutions to the solar neutrino problem. Our
analysis shows that the FCNC solutions with massless neutrinos provide a good
fit to the latest solar neutrino data. Predictions for future experiments are
formulated which will permit further tests of these solutions.


title:
Resummation analysis of the $\tau$ decay width using the four-loop
  $\beta$-function

abstract:
  We extract the strong coupling constant $\alpha_s(m_\tau^2)$ from the
semileptonic $\tau$ decay width taking into account resummation effects from
the running of the strong coupling constant. In the $\overline{\rm MS}$ scheme
the result reads $\alpha_s=0.375\pm 0.007$ to third order and
$\alpha_s=0.378\pm 0.007$ to fourth order in the $\beta$-function,
respectively, where we use the recently computed four-loop coefficient
$\beta_3$. These values for the coupling constant have to be compared with the
value $\alpha_s=0.354\pm 0.005$ derived from a third order analysis of $\tau$
decays. We determine the exact value of the convergence radius of the
perturbation series by analyzing the singularity structure of the complex
coupling constant plane.


title: Connections Between Inclusive and Exclusive Semileptonic B Decay

abstract:
  B decay sum rules relate exclusive B semileptonic decay matrix elements to
forward B-meson matrix elements of operators in HQET. At leading order the
operators that occur are the b-quark kinetic energy $\lambda_1$ and
chromomagnetic energy $\lambda_2$. The latter is determined by the measured
$B^*-B$ mass splitting. The derivation of these sum rules is reviewed and
perturbative QCD corrections are discussed. A determination of $\lambda_1$ and
the energy of the light degrees of freedom in a B-meson, $\bar\Lambda$, from
semileptonic B decay data is presented. Future prospects for improving these
sum rules are discussed.


title:
The UA(1) problem and the role of correlated q qbar exchange in
  effective theories of QCD

abstract:
  The combined absence of physical realizations of the UA(1) symmetry possessed
by the classical QCD action in the chiral limit, and of an isoscalar Goldstone
boson associated with its spontaneous breakdown, has been dubbed the UA(1)
problem. A formal resolution of this problem proposed by 't Hooft relies on
instantons to provide a mass to the would-be Goldstone boson (eta '). An
alternate scheme for the generation of an eta ' mass proposed by Kogut and
Susskind derives from quark annihilation into gluons and a strong infrared
singularity in the gluon propagator associated with confinement. We demonstrate
here how such diagrams are generated in quark based effective theories by
including a certain class of diagrams which arise from correlated q qbar
exchange and are of higher order 1/N_c. A low energy energy expansion of this
corrections is of the form discussed by Witten, di Vecchia and Veneziano.


title: Towards resolution of the enigmas of P-wave meson spectroscopy

abstract:
  The mass spectrum of P-wave mesons is considered in a nonrelativistic
constituent quark model. The results show the common mass degeneracy of the
isovector and isodoublet states of the scalar and tensor meson nonets, and do
not exclude the possibility of a similar degeneracy of the same states of the
axial-vector and pseudovector nonets. Current experimental hadronic and \tau
-decay data suggest, however, a different scenario leading to the a_1 meson
mass \simeq 1190 MeV and the K_{1A}-K_{1B} mixing angle \simeq (37\pm 3)^o.
Possible s\bar{s} states of the four nonets are also discussed.


title: On D-wave meson spectroscopy and the $K^* (1410) - K^* (1680)$ problem

abstract:
  The mass spectrum of D-wave mesons is considered in a nonrelativistic
constituent quark model. The results show a common mass degeneracy of the
isovector and isodoublet states of the 1 $^3D_1$ and 1 $^3D_3$ nonets, and
suggest therefore that the $K^\ast (1680)$ cannot be the I=1/2 member of the 1
$^3D_1$ nonet. They also suggest that the $\eta _2(1870),$ presently omitted
form the Meson Summary Table, should be interpreted as the I=0 $s\bar{s}$ state
of the 1 $^1D_2$ nonet.


title: Towards resolution of the scalar meson nonet enigma

abstract:
  By the application of a linear mass spectrum to a composite system of both
the pseudoscalar and scalar meson nonets, we find three mass relations for the
masses of the scalar states which suggest the $q\bar{q}$ assignment for the
scalar meson nonet: $a_0(1320),$ $K_0^\ast (1430),$ $f_0(1500),$ $f_0'(980).$


title:
Constraint on axial-vector meson mixing angle from nonrelativistic
  constituent quark model

abstract:
  In a nonrelativistic constituent quark model we find a constraint on the
mixing angle of the strange axial-vector mesons, $35^o\stackrel{<}{\sim }
\theta _K\stackrel{<}{\sim }55^o,$ determined solely by two parameters: the
mass difference of the $a_1$ and $b_1$ mesons and the ratio of the constituent
quark masses.


title: Pair production of charged Higgs bosons in gluon-gluon collisions

abstract:
  We studied the pair production rate of charged Higgs bosons via gluon-gluon
collisions in the general two-Higgs-doublet model. The analysis of its
production are made with possible parameter values of Higgs sectors in this
model. We find that the production cross sections may be 4 to 41 fermi-bar in
the future LHC pp collider with these parameters. The calculation also shows
that this pair production process is not sensitive to the neutral Higgs masses,
therefore its measurment could not give more imformations about the neutral
Higgs bosons.


title: Pursuing interpretations of the HERA large-Q2 data

abstract:
  We explore interpretations of the anomaly observed by H1 and ZEUS at HERA in
deep-inelastic e^+ p scattering at very large Q^2. We discuss the possibilities
of new effective interactions and the production of a narrow state of mass 200
GeV with leptoquark couplings. We compare these models with the measured Q^2
distributions: for the contact terms, constraints from LEP2 and the Tevatron
allow only a few choices of helicity and flavour structure that could roughly
fit the HERA data. The data are instead quite consistent with the Q^2
distribution expected from a leptoquark state. We study the production cross
sections of such a particle at the Tevatron and at HERA. The absence of a
signal at the Tevatron disfavours the likelihood that any such leptoquark
decays only into e^+ q. We then focus on the possibility that the leptoquark is
a squark with R-violating couplings. In view of the present experimental limits
on such couplings, the most likely production channels are e^+d -> scharm_L or
perhaps e^+d->stop, with e^+s->stop a more marginal possibility. Possible tests
of our preferred model include the absence both of analogous events in e^- p
collisions and of charged current events, and the presence of detectable
cascade decays whose kinematical signatures we discuss. We also discuss the
possible implications for K->pi nu nubar, neutrinoless double-beta decay, the
Tevatron and for e^+ e^- ->q qbar and neutralinos at LEP2.


title:
Two-loop QCD Corrections to $b \to c$ Transitions at Zero Recoil:
  Analytical Results

abstract:
  We present analytical results for the $O(\alpha _s ^2)$ contributions to the
functions $\eta _A$ and $\eta _V$ which parameterize QCD corrections to
semileptonic $b \to c$ transitions at zero recoil. Previously obtained
approximate results are confirmed. The methods of computing the relevant
two-loop diagrams with two mass scales are discussed in some detail.


title: Quark Mass Anomalous Dimension to alpha_s**4

abstract:
  We present the results of analytic calculation of the quark mass anomalous
dimension to alpha_s**4.


title: High Q2-Anomaly at HERA and Supersymmetry

abstract:
  We discuss the recently observed excess of high Q2 neutral current deep
inelastic scattering events at HERA in the light of supersymmetry with broken
R-parity. We find more than one possible solution. We consider the
possibilities for testing these hypotheses at HERA, the TEVATRON and at LEP.
One lepton-number violating operator can account for both the HERA data and the
four-jet anomaly seen by ALEPH at LEP.


title:
Color-Octet Contributions to J/psi Photoproduction via Fragmentation at
  HERA

abstract:
  We study J/psi photoproduction via fragmentation at next-to-leading order in
the QCD-improved parton model, using the nonrelativistic factorization
formalism proposed by Bodwin, Braaten, and Lepage. We consider direct and
resolved photoproduction of prompt J/psi mesons and chi_{cJ} mesons radiatively
decaying to J/psi+gamma, taking into account the formation of both
color-singlet and color-octet c anti-c states. Adopting the values of the
long-distance color-octet matrix elements extracted from fits to prompt-J/psi
data recently taken at the Fermilab Tevatron, we predict that measurements of
J/psi photoproduction at DESY HERA should show a distinctive excess over the
expectation based on the color-singlet model at small values of the
inelasticity variable z. This is complementary to the expected enhancement at z
close to 1 due to the color-octet contribution to photon-gluon fusion.


title:
Using e-e+ to b b(bar) to test properties of new interactions at LEP2
  and higher energies

abstract:
  We show that in e-e+ colliders at energies above the Z-peak, the process e-e+
to b b(bar) becomes very sensitive to the presence of residual New Physics (NP)
effects described by the dim=6 SU(3)*SU(2)*U(1) gauge invariant operators
O(qW), O(qB) and O(bB). This observation should be combined with the already
known great sensitivity of the light fermion production through e-e+
annihilation above the Z-peak, to the bosonic operators O(DW) and O(DB). It is
important to emphasize that the effects of all these operators are largely
hidden at the Z-peak; while they are enhanced above it through the use the
"Z-peak subtracted representation". The observability limits for detecting
these operators at LEP2 and NLC, through such light fermion production
processes, are also established.


title: Dynamical Properties of Flux Tubes in the Friedberg-Lee Model

abstract:
  A dynamical model of confinement based on a microscopic transport description
of the Friedberg-Lee model is extended to explicit color degrees of freedom.
The string tension is reproduced by an adiabatic string formation from the
nucleon ground state. As a particular application, we address the question of
how a charmonium state might be dissociated by the strong color electric fields
when moving through a color electric flux tube and speculate on the importance
of such an effect with respect to the issue of $J/\psi $--suppression observed
in ultrarelativistic heavy ion collisions. Furthermore, we show the dynamical
breakup of flux tubes via $q-\bar{q}$-particle production and the
disintegration into mesons. There we encounter some problems within the
Vlasov-type realization of describing the motion of the quarks which can be
resolved by a molecular dynamical approach.


title: Non-factorizable Contributions to the Large Rapidity Gap at HERA

abstract:
  The large rapidity gap events from HERA are analyzed within a model
containing a pomeron and an $f$-reggeon contribution. The choice for the
pomeron contribution is based on the Donnachie-Landshoff model. The dependence
of the "effective intercept" of the pomeron on the momentum fraction $\beta$
and on its Bjorken variable $\xi$ is calculated.


title: The 4-loop quark mass anomalous dimension and the invariant quark mass

abstract:
  We present the analytical calculation of the four-loop quark mass anomalous
dimension in Quantum Chromodynamics within the minimal subtraction scheme. On
the basis of this result we find that the so-called invariant quark mass is a
very good reference mass for the accurate evolution of the running MS-bar quark
mass in phenomenological applications. We also obtain for the first time a
complete 4-th order perturbative QCD expression for a physical quantity, the
total Higgs boson decay rate into hadrons, and analyze the infrared fixed point
for this case.


title: What Can We Learn About Leptoquarks At LEP200?

abstract:
  We investigate the discovery potential for first generation leptoquarks at
the LEP200 $e^+e^-$ collider. We consider direct leptoquark searches using
single leptoquark production via resolved photon contributions which offers a
much higher kinematic limit than the more commonly considered leptoquark pair
production process. Depending on the coupling strength of the leptoquark,
search limits can be obtained to within a few GeV of $\sqrt{s}$. We also
consider LQ limits that can be obtained from t-channel interferences effects in
$e^+e^- \to hadrons$.


title:
Aspects of spontaneously broken N = 1 global supersymmetry in the
  presence of gauge interactions

abstract:
  We discuss models where N=1 global supersymmetry is spontaneously broken, at
the classical level, in the presence of non-anomalous gauge interactions. We
take such models as effective theories, valid up to some suitable scale and
arising from supergravity models with a light gravitino, and therefore we allow
them to contain non-renormalizable interactions. First, we examine the case
where the goldstino is a gauge singlet. We elucidate the model-independent
relations between supersymmetry-breaking masses and some associated
interactions, with special attention to the behaviour of some four-particle
scattering amplitudes in the high- and low-energy limits. The former gives
constraints from tree-level unitarity, the latter affects the phenomenological
lower bounds on the gravitino mass. In particular, we give new results for the
annihilation of photons into gravitinos, and discuss their implications. We
then examine the case with no neutral chiral superfields, so that the goldstino
is charged, and the gauge symmetry is also broken. In this context, we discuss
the singularity structure and the associated unitarity constraints, relating
the scales of supersymmetry and gauge symmetry breaking. We conclude by
commenting on possible realistic examples, where the broken gauge symmetry is
associated with grand or electroweak unification.


title: On the Expectations for Leptoquarks in the Mass Range of O(200 GeV)

abstract:
  A summary is given on the experimental bounds for the couplings and masses of
scalar and vector leptoquarks associated to the first fermion generation. We
investigate to which extent an interpretation of the recently reported excess
of events in the large $x$ and $Q^2$ range at HERA in terms of single
leptoquark production is compatible with other experimental results.


title:
Leptoquark/Squark Interpretation of HERA Events: Virtual Effects in e+e-
  Annihilation to Hadrons

abstract:
  In reference to the recently observed high Q^2, large x events in
deep-inelastic positron-proton scattering at HERA, various leptoquark and
supersymmetric scenarios are discussed. We study the impact of virtual
leptoquark or R-parity breaking squark exchange as well as generic contact
interaction on the production of quark-antiquark pairs in $e^+e^-$
annihilation, in particular at LEP2.


title: Unification Beyond GUTs: Gauge-Yukawa Unification

abstract:
  Gauge-Yukawa Unification (GYU) is a renormalization group invariant
functional relation among gauge and Yukawa couplings which holds beyond the
unification point in Grand Unified Theories (GUTs). We present here various
models where GYU is obtained by requiring the principles of finiteness and
reduction of couplings. We examine the consequences of these requirements for
the low energy parameters, especially for the top quark mass. The predictions
are such that they clearly distinguish already GYU from ordinary GUTs. It is
expected that it will be possible to discriminate among the various GYUs when
more accurate measurements of the top quark mass are available.


title: Aspects Of Heavy Quark Theory

abstract:
  Recent achievements in the heavy quark theory are critically reviewed. The
emphasis is put on those aspects which either did not attract enough attention
or cause heated debates in the current literature. Among other topics we
discuss (i) basic parameters of the heavy quark theory; (ii) a class of exact
QCD inequalities; (iii) new heavy quark sum rules; (iv) virial theorem; (v)
applications (|V_cb| from the total semileptonic width and from the B->D*
transition at zero recoil). In some instances new derivations of the previously
known results are given, or new aspects addressed. In particular, we dwell on
the exact QCD inequalities. Furthermore, a toy model is considered that may
shed light on the controversy regarding the value of the kinetic energy of
heavy quarks obtained by different methods.


title: Two-loop QCD corrections to semileptonic b decays at maximal recoil

abstract:
  We present a complete $O(\alpha_s^2)$ correction to the differential width of
the inclusive semileptonic decay $b\to cl\nu_l$ at the kinematical point of
vanishing invariant mass of the leptons, $q^2=0$. Together with the recently
computed $O(\alpha_s^2)$ correction at the upper boundary of the lepton
invariant mass spectrum, this new information permits an estimate of the
$O(\alpha_s^2)$ effect in the total inclusive semileptonic decay width $b\to
cl\nu_l$. We argue that the non-BLM part of the $O(\alpha_s^2)$ correction
gives at most 1% correction to the inclusive semileptonic decay width $b\to
cl\nu_l$. This significantly improves the credibility of extracting $|V_{cb}|$
from the inclusive semileptonic decays of the b-hadrons.


title: Quark mixings as a test of a new symmetry of quark Yukawa couplings

abstract:
  Based on the hierarchy exhibited by quarks masses at low energies, we assume
that Yukawa couplings of up and down quarks are related by $Y_u\propto Y_d^2$
at grand unification scales. This ansatz gives rise to a symmetrical CKM matrix
at the grand unification (GU) scale. Using three specific models as
illustrative examples for the evolution down to low energies, we obtain the
entries and asymmetries of the CKM matrix which are in very good agreement with
their measured values. This indicates that the small asymmetry of the CKM
matrix at low energies may be the effect of the renormalization group evolution
only.


title: String Unification, Spaghetti Diagrams and Infra-Red Fixed Points

abstract:
  The minimal supersymmetric standard model (MSSM), is perhaps the leading
candidate for new physics beyond the standard model, but it encounters
difficulties with string gauge unification and in addition does not shed any
light on the question of fermion masses. We consider a scenario in which the
MSSM is valid up to an energy scale of 10^16 GeV, but that above this scale the
theory is supplemented by extra vector-like representations of the gauge group,
plus a gauged U(1)_X family symmetry. In our approach the extra heavy matter
above the scale 10^16 GeV is used in two different ways: (1) to allow
(two-loop) gauge coupling unification at the string scale; (2) to mix with
quarks, leptons and Higgs fields via spaghetti diagrams and so lead to
phenomenologically acceptable Yukawa textures. We determine the most economical
models in which the extra matter can satisfy both constraints simultaneously.
We then give a general discussion of the infra-red fixed points of such models,
pointing out the conditions for infra-red stability, then discuss two
semi-realistic examples: a Higgs mixing model, and a quark mixing model.


title: Comment on Recent Argument That Neutrinos Are Not Majorana Particles

abstract:
  Existing data on neutrino-electron scattering do not imply that neutrinos are
not Majorana particles. The question of whether neutrinos are of Majorana or of
Dirac character remains completely open.


title: The Future of K Physics

abstract:
  We discuss the opportunities for experiments at the frontier of physics using
K-meson beams after the current round of precision experiments looking for CP
violation in the K meson decay amplitude and for flavor-changing neutral
currents are completed and the B-factories at KEK and SLAC are running. We
emphasize those experiments that will give complementary information on the
parameters of the Standard Model, especially the Cabibbo-Kobayashi-Maskawa
matrix elements, and on possible physics beyond the Standard Model.


title: High Energy Hadronic Total Cross-Sections

abstract:
  High energy hadronic total cross-section data are found to agree with the
predictions of a QCD-string picture.


title: T-Duality Considerations for Hadronic Strings

abstract:
  We show that a simple account of hadronic high energy total cross-sections
and of the observed masses and flavor-gauge-like couplings of the familiar
vector mesons is obtained in a hadronic string model suggested by QCD in the
limit of a large number of colors. Our picture involves a Minkowski space which
in addition to the well established continuous one time and three space
dimensions is endowed with an extra discrete space dimension involving a
minimal 2-point lattice with spacing of order 10^{-14} cm in one of the two
T-dual pictures. New mesonic states with characteristic decay modes are
expected in such a picture.


title: Effective Field Theory and Matching in Non-Relativistic Gauge Theories

abstract:
  The effective Lagrangian and power counting rules for non-relativistic gauge
theories are derived via an expansion in $1/c$. It is shown that the $1/c$
expansion leads to an effective field theory which incorporates a multipole
expansion. Failure to use this expansion in the low energy theory leads to a
loss of predictive power as the matching procedure becomes intractable. It is
emphasized that there is not a one-to-one correspondence between operators in
the modified low energy theory and those in the heavy quark effective theory.We
also discuss the Lamb shift as a pedagogical example of the power counting
scheme.


title: Comments on the high-$Q^2$ HERA anomaly

abstract:
  Taking the reported high-Q^2 anomaly at HERA as a signal of new physics, we
show that several independent considerations point towards s-channel leptoquark
production as the most attractive interpretation. We argue that even this
option is highly constrained by flavor-changing processes: the couplings must
be accurately diagonal in the quark and lepton mass eigenstate basis and should
preserve individual quark and lepton family numbers. We propose a dynamical
mechanism that might produce this pattern; it has distinctive experimental
consequences.


title:
Is there Anomalous J/psi Suppression in Present-day Heavy-ion
  Collisions?

abstract:
  We re-analyse the data on J/psi cross sections for proton-nucleus and
nucleus-nucleus collisions obtained by the CERN experiments NA38, NA51 and
NA50. Our systematic analysis of error propagation shows that the no anomalous
suppression of J/psi in Pb-Pb collisions can be substantiated at 95% confidence
limit. The significance of the NA50 result would be enhanced by more precise
p-A data on J/psi cross sections.


title:
Measuring the two-photon decay width of Intermediate-mass Higgs at a
  photon-photon collider

abstract:
  Feasibility of a measurement of the partial decay width of the
intermediate-mass Higgs boson into two photons at a photon-photon collider is
studied by a simulation. The QCD radiative correction for quark pair background
processes is taken into account for the realistic background estimation. It is
found that the two-photon decay width can be measured with the statistical
error of 7.6 % with about one year of experiment. The impact of the measurement
of the two-photon decay width to look for the new physics beyond is
demonstrated.


title:
Inclusive Jet Production with Virtual Photons in Next-to-Leading Order
  QCD

abstract:
  We present a next-to-leading order calculation for the virtual
photoproduction of one and two jets in $ep$ collisions. Soft and collinear
singularities are extracted using the phase space slicing method. The collinear
photon initial state singularity depends logarithmically on the mass of the
virtual photon and is absorbed into the virtual photon structure function. An
$\overline{MS}$ factorization scheme is defined similarly to the real photon
case. Numerical results are presented for HERA conditions using the Snowmass
jet definition for inclusive single jet and dijet cross sections. We study the
dependence of these cross sections on the transverse energies and rapidities of
the jets. Finally, we compare the ratio of the experimentally defined resolved
and direct cross sections with recent ZEUS data as a function of the photon
virtuality $P^2$.


title: Single-Spin Asymmetries in $p^\uparrow p \to \pi X$ and Chiral Symmetry

abstract:
  We study a possible origin of single spin asymmetries in the large $p_T$
inclusive production of hadrons in the scattering of unpolarized protons or
leptons on transversely polarized nucleons. Such asymmetry is related to the
single-spin asymmetry for the process $\p^\uparrow \to q+X$ or, equivalently,
to the off-diagonal matrix element of the quark density operator $\bar \psi
\gamma^+ \psi$; this quantity need not be zero if transverse momentum and
spin-isospin interactions are taken into account. The different signs for the
large single spin asymmetries observed in $\p^\uparrow p \to \pi^+ X$ and
$\p^\uparrow p \to \pi^- X$ can be explained as a consequence of chiral
symmetry. Crucial tests of the model are suggested.


title: Corrections to the Pagels-Stokar Formula for f_\pi

abstract:
  Within the composite operator formalism we derive a formula for the pion
decay constant $f_{\pi}$, as defined directly from the residue at the pion pole
of the meson propagator, rather than from the matrix element of the axial
current. The calculation is performed under some simplifying assumptions, and
we verify the complete consistency with soft-pion results, in particular with
the Adler-Dashen relation. The formula one obtains for (the pole-defined)
$f_{\pi}^2$ differs from the previous Pagels-Stokar expression by an additive
term, and it still provides $f_{\pi}^2$ in terms of the quark self-energy. We
make some numerical estimates leading to $(30 \div 40)%$ deviation for
$f_{\pi}^2$ with respect to the Pagels-Stokar formula.


title:
Next-to-Leading Order QCD Corrections to Three-Jet Cross Sections with
  Massive Quarks

abstract:
  We calculate the cross section for $e^+ e^-$ annihilation into three jets for
massive quarks at next-to-leading order in perturbative QCD, both on and off
the $Z$ resonance. Our computation allows the implementation of any jet
clustering algorithm. We give results for the three-jet cross section involving
$b$ quarks for the JADE and Durham algorithm at c.m. energies $\sqrt s = m_Z$.
We also discuss a three-jet observable that is sensitive to the mass of the $b$
quark.


title: Is the Cabibbo-Kobayashi-Maskawa Matrix Symmetric at the GUT Scale?

abstract:
  By use of the one-loop renormalization group equations and current
experimental data, we study the off-diagonal asymmetries of the
Cabibbo-Kobayashi-Maskawa (CKM) matrix at the GUT scale in the framework of the
standard model as well as its two Higgs and supersymmetric extensions. It is
concluded that the possibility of a symmetric CKM matrix at the GUT scale has
almost been ruled out.


title:
Structure of spin-dependent scattering amplitude and spin effects at
  small angles at RHIC energies

abstract:
  Spin-dependent pomeron effects are analyzed for elastic $pp$ scattering and
calculations for spin-dependent differential cross sections, analyzing power
and double-spin correlation parameters are carried out for the energy range of
the Relativistic Heavy Ion Collider (RHIC) at BNL. In this energy range, $50
\leq \sqrt{s} \leq 500 \gev$, the structure of pomeron-proton coupling can be
measured at RHIC with colliding polarized proton beams.


title: The First Moment of delta g(x) -- a Comparative Study

abstract:
  The sensititivity of various future polarization experiments to the first
moment Delta g of the polarized gluon density is elucidated in detail. It is
shown to what extent the first moment can be extracted from the future data as
compared to the higher moments. We concentrate on two processes which in the
near future will become an important source of information on the polarized
gluon density, namely the photoproduction of open charm to be studied at CERN
(COMPASS) and SLAC and the production of direct photons at RHIC.


title: Background thermal depolarization of electrons in storage rings

abstract:
  We discuss the influence of the background thermal bath on the depolarization
of electrons in high-energy storage rings, and on the photon emission
associated with the spin flip. We focus, in particular, on electrons at LEP. We
show that in a certain interval of solid angles the photon emission is enhanced
several orders of magnitude because of the presence of the thermal bath.
Notwithstanding, the overall depolarization induced by the background thermal
bath at LEP conditions is much smaller than the one induced by plain
acceleration at zero-temperature and can be neglected in practical situations.
Eventually we discuss in what conditions the background thermal bath can
enhance the overall depolarization by several orders of magnitude.


title: Relativity and the Minimum Slope of the Isgur-Wise Function

abstract:
  Sum rules based upon heavy quark effective theory indicate that the
Isgur-Wise function $\xi(w)$ has a minimum slope as w approaches 1, which is
zero for light degrees of freedom with zero spin and 1/4 for light spin 1/2.
Quark-model studies reveal sources for a minimum slope from a variety of
relativistic effects. In this paper the origins of the minimum slope in the
sum-rule and quark-model approaches are compared by considering hadrons with
arbitrary light spin. In both approaches the minimum slope increases with the
light spin, but there appears to be no detailed correspondence between the
quark-model and sum-rule approaches.


title: Contact Interactions and high-Q2 events in e^+ p collisions at HERA

abstract:
  We consider $e e q q$ contact interactions as a possible origin of an excess
of events above Standard Model predictions in $e^+ p \to e^+ jet$ at high $Q^2$
observed by the H1 and ZEUS collaborations at HERA. The HERA data prefer
chirality RL or LR contact terms and atomic physics parity violation
measurements severely limit parity-odd contact terms. With equal left-right and
right-left chirality interactions at an effective scale of order 3 TeV we are
able to reproduce the main features of the HERA data and still be consistent
with Drell-Yan pair production at the Tevatron and hadron production at LEP 2
and TRISTAN.


title: Gauge-Mediated Supersymmetry Breaking without Fundamental Singlets

abstract:
  The messenger sector of existing models of gauge-mediated supersymmetry
breaking may be simplified by using a non-renormalizable superpotential term to
couple the vector-like quark and lepton messenger fields to a chiral
gauge-invariant of the supersymmetry-breaking sector. This eliminates the need
for a fundamental singlet and for an additional gauge sector needed to generate
appropriate expectation values for the singlet component fields. This scenario
is more natural if the supersymmetry-breaking sector itself involves a
non-renormalizable superpotential. Several examples are constructed based on
non-renormalizable $SU(n)\times SU(n-1)$ supersymmetry-breaking theories.


title:
Mixing of eta-eta' Mesons in J/psi Decays into a Vector and a
  Pseudoscalar Meson

abstract:
  The octet-singlet mixing angle $\theta_P$ in the pseudoscalar meson nonet is
deduced from the rich set of accurate data on $J/\psi$ decays into a vector and
a pseudoscalar meson. Corrections due to non-ideal $\omega$-$\phi$ mixing have
been included for the first time and turn out to be crucial to find $\theta_P =
-16.9 \pm 1.7$ degrees, which is appreciably less negative than previous
results coming from similar analyses.


title: Charm as a Key to Diffractive Processes

abstract:
  The diffractive production of open charm in deep-inelastic scattering is
studied in the semiclassical approach which has been proposed recently. In this
approach, the leading order process contains a charm quark pair and an
additional gluon in the diffractive final state. The $p_{\perp}$-spectrum and
the diffractive mass distribution are evaluated and compared with predictions
based on perturbative two-gluon exchange calculations for charm quark pair
production. It is shown that the $p_{\perp}$-spectrum provides a clear test of
the underlying partonic process whereas the diffractive mass distribution
reflects the non-perturbative mechanism of colour neutralization.


title:
Nonequilibrium Corrections to the Spectra of Massless Neutrinos in the
  Early Universe

abstract:
  Distortion of the equilibrium spectra of cosmic neutrinos due to interaction
with hotter electrons and positrons in the primeval cosmic plasma is
considered. The set of integro-differential kinetic equations for neutrinos is
accurately numerically solved. The relative corrections to neutrino energy
densities are approximately 0.9% for $\nu_e$ and 0.4% for $\nu_\mu$ and
$\nu_\tau$. This effect results in $1.4 \cdot 10^{-4}$ increase in the
primordial $^4 He$ abundance.


title: Removing flavor changing neutral interactions from leptoquark exchange

abstract:
  We look for a mechanism that removes without numerical fine tuning the strong
constraint imposed by the flavor changing neutral current interaction of
leptoquark exchange. If n x n degenerate leptoquarks couple universally to n
generations of quarks and leptons in the weak basis, not only can the neutral
current interactions be flavor diagonal, but also the charge current
interaction takes exactly the same form as W exchange at low energies. Atomic
parity violation still imposes tight constraints. Electroweak doublets with
some left-right symmetry have the best chance to be the lightest leptoquarks.


title:
Electroweak Breaking and the mu problem in Supergravity Models with an
  Additional U(1)

abstract:
  We consider electroweak symmetry breaking in supersymmetric models with an
extra non-anomalous U(1)' gauge symmetry and an extra standard-model singlet
scalar S. For appropriate charges the U(1)' forbids an elementary mu term, but
an effective mu is generated by the VEV of S, leading to a natural solution to
the mu problem. There are a variety of scenarios leading to acceptably small
Z-Z' mixing and other phenomenological consequences, all of which involve some
but not excessive fine tuning. One class, driven by a large trilinear soft
supersymmetry breaking term, implies small mixing, a light Z' (e.g., 200 GeV),
and an electroweak phase transition that may be first order at tree level. In
another class, with m_S^2 < 0 (radiative breaking), the typical scale of
dimensional parameters, including M_{Z'} and the effective mu, is O(1 TeV), but
the electroweak scale is smaller due to cancellations. We relate the soft
supersymmetry breaking parameters at the electroweak scale to those at the
string scale, choosing Yukawa couplings as determined within a class of string
models. We find that one does not obtain either scenario for universal soft
supersymmetry breaking mass parameters at the string scale and no exotic
multiplets contributing to the renormalization group equations. However, either
scenario is possible when the assumption of universal soft breaking is relaxed.
Radiative breaking can also be generated by exotics, which are expected in most
string models.


title: Scaling Violation through Squark and Light Gluino Production

abstract:
  In the light gluino scenario, squarks in the 100 GeV mass region can be
copiously produced at the Tevatron without a second heavy particle. Their
subsequent dijet decay into quark plus gluino leads to non-scaling structure in
the inclusive jet X_T distribution. The expected behavior is similar to recent
observations.


title:
Generalized Recurrence Relations for Two-loop Propagator Integrals with
  Arbitrary Masses

abstract:
  An algorithm for calculating two-loop propagator type Feynman diagrams with
arbitrary masses and external momentum is proposed. Recurrence relations
allowing to express any scalar integral in terms of basic integrals are given.
A minimal set consisting of 15 essentially two-loop and 15 products of one-loop
basic integrals is found. Tensor integrals and integrals with irreducible
numerators are represented as a combination of scalar ones with a higher
space-time dimension which are reduced to the basic set by using the
generalized recurrence relations proposed in Ref.[1] (Phys.Rev.D54 (1996)
6479).


title:
Soft Scalar-Mass Sum Rule in Gauge-Yukawa Unified Models and Its
  Superstring Interpretation

abstract:
  It is shown that a certain sum rule for soft supersymmetry-breaking scalar
masses, which has been recently found in a certain class of superstring models,
is universal for gauge-Yukawa unified models. To explain this coincidence, we
argue that the low-energy remnant of the target-space duality invariance in the
effective supergravity of compactified superstrings can be identified with the
(broken) scale invariance in gauge-Yukawa unified models, and that gauge-Yukawa
unification which is indispensable for the sum rule to be satisfied follows
from the matching of anomalies.


title: Infra-Red Fixed Points in an Asymptotically Non-Free Theory

abstract:
  We investigate the infrared fixed point structure in asymptotically free and
asymptotically non-free theory. We find that the ratios of couplings converge
strongly to their infrared fixed points in the asymptotically non-free theory.


title: Comment on "Remark on the external-field method in QCD sum rules"

abstract:
  It is proved, that suggested by Jin modified formalism in the external-field
method in QCD sum rules exactly coincides with the formalism used before.
Therefore, unlike the claims of ref.1, this formalism cannot improve the
predictability and reliability of external-field sum rule calculations in
comparison with those, done by the standard approach.
  PACS number(s): 12.38.Lg, 11.55.Hx


title: Inclusion of Chemical Potential for Scalar Fields

abstract:
  There are two possible methods for the inclusion of the chemical potential in
a relativistic bosonic field theory. The most popular method has recently been
criticised by some authors, so much so as to require a re-analysis of the
entire problem. I here present a new approach to the inclusion of the chemical
potential that uses the second method and zeta-function regularisation
techniques. I first apply it to the non-interacting field, obtaining an
expression for the effective potential which is formally coincident with the
well-known one from the first method. My approach, however, seems here
mathematically more rigorous since it excludes the presence of the
multiplicative anomaly. I then obtain a new expression for the one loop
effective potential for the interacting field. This is regularised, presents
less cryptic excitation energies, shows Goldstone excitations, and in the
non-interacting limit gives the expected expression. The high-temperature
expansion is calculated easily and with clarity, and confirms the results of
the first method for the critical temperature.


title:
Bag Model Prediction for the Nucleon's Chiral-odd Twist-3 Distribution
  h_L(x,Q^2) at High Q^2

abstract:
  We study the Q^2 evolution of the nucleon's chiral-odd twist-3 distribution
h_L(x,Q^2) starting from the MIT bag model calculation. A simple GLAP equation
for h_L(x,Q^2) obtained at large N_c is used for the Q^2 evolution. The
correction due to the finite value of N_c is O(1/N_c^2)\sim 10% level. It turns
out that the twist-3 contribution to h_L(x,Q^2) is significantly reduced at
Q^2=10 GeV^2 in contrast to the g_2(x,Q^2) case. This is due to the fact that
the corresponding anomalous dimension for h_L is larger than that for g_2 at
small n (spin).


title:
Short Distance QCD Contribution to the Electroweak Mass Difference of
  Pions

abstract:
  It is known that the short distance QCD contribution to the mass difference
of pions is quadratic on the quark masses, and irrelevant with respect to the
long distance part. It is also considered in the literature that its
calculation contain infinities, which should be absorbed by the quark mass
renormalization. Following a prescription by Craigie, Narison and Riazuddin, of
a renormalization group improved perturbation theory to deal with the
electromagnetic mass shift problem in QCD, we show that the short distance QCD
contribution to the electroweak pion mass difference (with $m_u=m_d\neq0$) is
finite and, of course, its value is negligible compared to other contributions.


title: Electroweak phase transition and baryogenesis in the MSSM

abstract:
  We have analyzed baryogenesis in the MSSM for the light stop scenario, where
the phase transition is strong enough first order. We have found that enough
baryon asymmetry can be generated provided that the phase of $\mu$ be $\simgt$
0.01. Constraints from the electric dipole moment of the neutron enforce the
first and second generation squarks to have masses O(few) TeV


title: Scalar Field Dynamics in Friedman Robertson Walker Spacetimes

abstract:
  We study the non-linear dynamics of quantum fields in matter and radiation
dominated universes, using the non-equilibrium field theory approach combined
with the non-perturbative Hartree and the large N approximations. We examine
the phenomenon of explosive particle production due to spinodal instabilities
and parametric amplification in expanding universes with and without symmetry
breaking. For a variety of initial conditions, we compute the evolution of the
inflaton, its quantum fluctuations, and the equation of state. We find
explosive growth of quantum fluctuations, although particle production is
somewhat sensitive to the expansion of the universe. In the large N limit for
symmetry breaking scenarios, we determine generic late time solutions for any
flat Friedman-Robertson-Walker cosmology. We also present a complete and
numerically implementable renormalization scheme for the equation of motion and
the energy momentum tensor in flat FRW cosmologies. In this scheme the
renormalization constants are independent of time and of the initial
conditions.


title: The resummation approach to evolution equations

abstract:
  We derive the evolution equations of parton distribution functions
appropriate in different kinematic regions in a unified and simple way using
the resummation technique. They include the Gribov-Lipatov-Altarelli-Parisi
equation for large momentum transfer $Q$, the Balitskii-Fadin-Kuraev-Lipatov
equation for a small Bjorken variable $x$, and the
Ciafaloni-Catani-Fiorani-Marchesini equation which unifies the above two
equations. We propose a modified Balitskii-Fadin-Kuraev-Lipatov equation from
the view point of the resummation. This modified version possesses an intrinsic
$Q$ dependence and its predictions for the structure function $F_2(x,Q^2)$ are
consistent with the HERA data.


title: Z polarization in the Higgs boson signal at the LHC

abstract:
  We examine a method of studying the Z polarization in $H\to ZZ \to \ell^+
\ell^- \nu \bar{\nu}$ in proton-proton collisions at the Large Hadron Collider
(LHC). Included are the dominant contributions: gluon fusion production of the
Higgs boson, continuum production of Z pairs, and the Z+missing jet QCD
background. The polarization signal is distinguishable from the background for
Higgs masses less than or equal to $\sim 700$ GeV, for an integrated luminosity
of 10^5 pb^{-1}.


title: Higgs Boson Discovery and Properties

abstract:
  We outline issues examined and progress made by the Light Higgs Snowmass 1996
working group regarding discovering Higgs bosons and measuring their detailed
properties. We focused primarily on what could be learned at LEP2, the Tevatron
(after upgrade), the LHC, a next linear $\epem$ collider and a $\mupmum$
collider.


title: Hadroproduction of Charm and Beauty

abstract:
  Recent results on the hadroproduction of charm and beauty are discussed in
the context of the current theoretical and experimental status. The areas
covered include production of open charm and beauty particles and charm and
beauty quarkonia. Experimental results from both fixed target and colliding
beam experiments are presented and compared to theoretical predictions.
Predictions based on QCD perturbation theory are generally successful in
explaining the shapes of differential cross sections but underestimate the
scale of the cross section by factors of 2-3. An exception is production of the
vector meson quarkonia which cannot be satisfactorily explained by perturbative
processes alone.


title: Are the H1 and ZEUS "High Q^2 Anomalies" Compatible with Each Other?

abstract:
  Both ZEUS and H1 have recently reported an excess of events at high $Q^2$ and
high Bjorken--$x$. However, the $x$ distributions differ considerably;
moreover, H1 sees more events with lower luminosity. Taken separately, the $x$
distributions and the number of observed events are consistent between the two
experiments at the few percent level. However, when combined it becomes clear
that the results of H1 and ZEUS are as (in)compatible with each other as each
is with the Standard Model.


title: Extending Sensitivity for Low-Mass Neutral Heavy Lepton Searches

abstract:
  We point out the importance of two-body final states of weak isosinglet
neutral heavy leptons predicted in several models of new physics beyond the
standard model. We concentrate on muon-type neutral heavy leptons $L_\mu^0$
with mass $M<2$ GeV which can be searched for with increased sensitivity at a
new round of neutrino experiments at CERN and Fermilab. Providing explicit
decay rate formulae for the $e e \nu$, $e\mu \nu$, $\mu \mu \nu$, $\pi \mu$,
$\rho \mu$, and $a_1\mu$ final states, we use general scaling features to
estimate sensitivity of $L_\mu^0$ searches in current and future experiments,
emphasizing the importance of the $\pi \mu$ decay mode.


title: Spin-Flavour Oscillations and Neutrinos from SN1987A

abstract:
  The neutrino signal from SN1987A is analysed with respect to spin-flavour
oscillations between electron antineutrinos, $\bar{\nu}_{e}$, and muon
neutrinos, $\nu_{\mu}$, by means of a maximum likelihood analysis.
  Following Jegerlehner et al. best fit values for the total energy released in
neutrinos, $E_t$, and the temperature of the electron antineutrino,
$T_{\bar{\nu}_{e}}$, for a range of mixing parameters and progenitor models are
calculated. In particular the dependence of the inferred quantities on the
metallicity of the supernova is investigated and the uncertainties involved in
using the neutrino signal to determine the neutrino magnetic moment are pointed
out.


title: On dipenguin contribution to D^0 - \bar D^0 mixing

abstract:
  We study the impact of the four-quark dipenguin operator to the D^0 - \bar
D^0 mixing. It is shown to contribute to the short distance piece at the same
order of magnitude as the box diagram.


title: Lepton CP Asymmetries in B Decays

abstract:
  In the decay of Upsilon(4S, the decay time distribution of Upsilon(4S) -> f +
X, where f is a final state that B^0 or B^0bar can decay to, is the sum of the
decay time distributions of B^0 -> f and B^0bar -> f. Using this general rule,
we estimate the sensitivity of single lepton CP violation measurements with
respect to that of traditional di-lepton measurements. We find that the
sensitivity of the single lepton method is comparable to or better than that of
the di-lepton method. The two data samples are largely statistically
independent, so that they can be combined to improve sensitivity. The advantage
of the single lepton measurement increases for large mixings, which suggests
that the single lepton method holds promise for B_s. We also discuss lepton
asymmetry measurements on the Z^0 peak and in hadron colliders. The achievable
sensitivity with the currently available data is already in the range relevant
to standard model predictions. PACS numbers: 11.30.Er, 13.20.Gd, 13.20.He,
03.65.Bx


title: Much Ado About Leptoquarks: A Comprehensive Analysis

abstract:
  We examine the phenomenological implications of a 200 GeV leptoquark in light
of the recent excess of events at HERA. Given the relative predictions of
events rates in e^+p versus e^-p, we demonstrate that classes of leptoquarks
may be excluded, including those contained in E_6 GUT models. It is shown that
future studies with polarized beams at HERA could reveal the chirality of the
leptoquark fermionic coupling and that given sufficient luminosity in each
e^\pm_{L,R} channel the leptoquark quantum numbers could be determined. The
implications of 200-220 GeV leptoquarks at the Tevatron are examined. While
present Tevatron data most likely excludes vector leptoquarks and leptogluons
in this mass region, it does allow for scalar leptoquarks. We find that while
leptoquarks have little influence on Drell-Yan production, further studies at
the Main Injector are possible in the single production channel. We investigate
precision electroweak measurements as well as the process e^+e^-\to q\bar q at
LEP II and find they provide no further restrictions on these leptoquark
models. We then ascertain that cross section and polarization asymmetry
measurements at the NLC provide the only direct mechanism to determine the
leptoquark's electroweak quantum numbers. The single production of leptoquarks
in \gamma e collisions by both the backscattered laser and Weisacker-Williams
techniques at the NLC is also discussed. Finally, we demonstrate that we can
obtain successful coupling constant unification in models with leptoquarks,
both with or without supersymmetry. The supersymmetric case requires the GUT
group to be larger than SU(5) such as flipped SU(5)\times U(1)_X.


title:
Constraints on Leptoquark Masses and Couplings from Rare Processes and
  Unification

abstract:
  Motivated by the recent experimental data at HERA and ZEUS, which have
reported evidence for leptoqark production at Sqrt{s}=314 GeV with a mass at
M_D=200 GeV we consider its implications in unified supersymmetric theories. We
also present calculations for leptoquark production incorporating the existing
limits from other exotic reactions on its couplings and other relevant
parameters.


title: Complete spin structure of the pion-nucleon-loop delta self-energy

abstract:
  The complete spin structure of the pion-nucleon-loop contribution to the
delta self-energy and dressed propagator is calculated in vacuum, with the most
general form of the pion-nucleon-delta vertex. The imaginary parts of the ten
Lorentz-scalar coefficients are calculated in closed form, while the real parts
are obtained numerically from a dispersion relation. The effect of the
pion-nucleon-delta coupling constants and form-factor on the pion-nucleon
phase-shift in the spin-3/2 isospin-3/2 channel is studied.


title:
Elementary derivation of a recently proposed integral representation for
  permanents

abstract:
  A recently proposed integral representation for permanents is rederived using
only elementary combinatorics. For this proof the assumption that the matrix,
for which the permanent is calculated, has an inverse is not necessary.


title: $B_c$ Meson at LHC

abstract:
  In the framework of perturbative QCD and potential models of heavy
quarkonium, total cross-sections and differential characteristics of hadronic
production for different spin states of the $B_c$-meson family are calculated
at energies of LHC. Theoretical predictions for masses and branching ratios of
$B_c$ decays are given, which allows one to make estimates for an expected
number of reconstructed events with $B_c$.


title: A New State Of Hadronic Matter At High Density

abstract:
  We propose in this article that if the chemical potential exceeds a critical
value in dense hadronic medium, a first-order phase transition to a new state
of matter with Lorentz symmetry spontaneously broken (in addition to the
explicit breaking) takes place. As a consequence, light vector mesons get
excited as ``almost'' Goldstone bosons. Since the light vector mesons
dominantly couple to photons, the presence of these new vector mesons could
lead to an enhancement in the dilepton production from dense medium at an
invariant mass lower than the free-space vector-meson mass. We provide a
low-energy quark model which demonstrates that the above scenario is a generic
case for quark theories with a strong interaction in the vector channel. We
discuss possible relevance of this phase to the phenomenon of the enhanced
dilepton production at low invariant masses in relativistic heavy-ion
collisions.


title: On the QCD Evolution of the Transversity Distribution

abstract:
  The QCD evolution of the transversity distributions is investigated and
compared to that of the helicity distributions. It is shown that they differ
largely in the small-$x$ region. It is also proved that the evolution preserves
Soffer's inequality among the three leading-twist distribution functions.


title:
Inclusive Semileptonic Decays of Polarized $\Lambda_b$ Baryons into
  Polarized $\tau$-Leptons

abstract:
  We employ OPE techniques within HQET to calculate the inclusive semileptonic
decays of polarized $\Lambda_b$ baryons. Lepton mass effects are included which
enables us to also discuss rates into polarized $\tau$-leptons. We present
explicit results for the longitudinal polarization of the $\tau$ in the
$\Lambda_b$ rest frame as well as in the $(\tau ^-, \bar \nu_\tau)$ c.m. frame.
In both cases we make use of novel calculational techniques which considerably
simplify the calculations. The transverse polarization components of the $\tau$
are calculated in the $(\tau^-,\bar\nu_\tau)$ c.m. frame. We delineate how to
measure the full set of 14 polarized and unpolarized structure functions of the
decay process by angular correlation measurements. A set of observables are
identified that allow one to isolate the contributions of the two $O(1/m_b^2)$
nonperturbative matrix elements $K_b$ and $\epsilon_b$.