title: The Highest Energy Cosmic Rays and Particle Physics

abstract:
  It has been argued that the observations of cosmic particles with energies in
excess of $10^8$ TeV represent a puzzle. Its solution requires new astrophysics
or new particle physics. We show that the latter is unlikely given that the
scale associated with a new particle physics threshold must be of order 1 GeV,
not TeV and above, in order to resolve the problem. In most cases such new
physics should have been revealed by accelerator experiments. We examine the
possibility that the highest energy cosmic rays are initiated by non-standard
interactions of neutrinos in the atmosphere. We show that proposals in this
direction either violate s-wave unitarity or fall short of producing a sizeable
effect by several orders of magnitude.


title: Color-singlet and color-octet J/psi production in top quark rare decays

abstract:
  J/psi production in top quark rare decays is investigated under the framework
of NRQCD factorization formalism. Various production channels are studied, and
we find that the contributions from the color-singlet quark fragmentation and
the color-octet gluon fragmentation are both over 3 orders larger than that
from the leading order color-singlet process. The numerical results show that
the branching ratio B(t -> c + J/psi + X) is about 10^{-14} in the SM, and
10^{-10} in the MSSM.


title: Real-time contour propagator for high temperature dimensional reduction

abstract:
  We discuss the extension of dimensional reduction in thermal field theory at
high temperature to real-time correlation functions. It is shown that the
perturbative corrections to the leading classical behavior of a scalar bosonic
field theory are determined by an effective contour propagator. On the
real-time-branch of the time-path contour the effective propagator is obtained
by subtracting the classical propagator from the contour propagator of thermal
field theory, whereas on the Euclidean branch it reduces to the non-static
Matsubara propagator of standard dimensional reduction.


title: Status of three flavor baryon chiral perturbation theory

abstract:
  I review the present status of three flavor baryon chiral perturbation theory
in the heavy fermion formalism. It is argued that precise calculations have to
include all terms quadratic in the quark masses. As examples, I consider the
chiral expansion of the octet baryon masses, the baryon magnetic moments and
kaon photoproduction off nucleons.


title: Identification of Virtual New Physics Effects at a Linear Collider

abstract:
  It is shown that, at a 500 GeV LC, a number of different theoretical models
would be unambigously identified by their virtual effects. Negative limits in
case of no signal identification are also derived.


title:
Tests for the asymptotic behaviour of the gamma^* --> gamma pi^0 form
  factor

abstract:
  The gamma^* --> gamma pi^0 transition measured at different photon
virtualities already provides us with a clean test for the behaviour of the
pi^0 gamma^* gamma off-shell axial anomaly at large time-like squared momenta.
It also allows reliable predictions for the branching ratio of heavy quarkonium
decays into omega pi^0.


title: How Small Can the Light Quark Masses Be?

abstract:
  We derive rigorous lower bounds for the combinations of light quark masses
(m_s+m_u) and (m_d+m_u).


title: Probing the quark condensate by means of pi-pi scattering

abstract:
  The available experimental information is consistent with the Weinberg
predictions for the threshold parameters of pi-pi-scattering. The data,
however, only test those relations that are insensitive to the quark masses m_u
and m_d. Recent theoretical progress leads to remarkably sharp predictions for
the behaviour of the S- and P-wave phase shifts in the elastic region -- one of
the very few low energy phenomena in QCD, where theory is ahead of experiment
and where new precision data would subject the theory to a crucial test (Talk
given at the DAFCE workshop, Frascati, November 1996).


title: The most promising ways to measure V_ub

abstract:
  I review currently discussed methods to determine the CKM mixing matrix
element $|V_{ub}|$ from experimental data. Although the theory of inclusive
decays and their spectra has entered a model-independent stage, its predictions
are still sensitive to various input parameters, in particular the poorly known
$b$ quark mass. At present, determinations from exclusive channels, notably
$B\to\pi e \nu$, seem slightly more accurate and allow determination of
$|V_{ub}|$ from the spectrum in the momentum transfer to the leptons with a
theoretical uncertainty of $\sim 10%$.


title: On the 1/N expansion in chiral perturbation theory

abstract:
  Talk given at QCD 97, Montpellier, July 1997. In the first part of the talk,
I presented a review of the results for the light quark masses obtained on the
basis of chiral perturbation theory. As this material is described elsewhere,
the following notes only concern the second part, which dealt with the
behaviour of the effective theory in the large N_c limit.


title: Do experiments suggest a hierarchy problem?

abstract:
  The hierarchy problem of the scalar sector of the standard model is
reformulated, emphasizing the role of experimental facts that may suggest the
existence of a new physics large mass scale, for instance indications of the
instability of the matter, or indications in favor of massive neutrinos. In the
see-saw model for the neutrino masses a hierarchy problem arises if the mass of
the right-handed neutrinos is larger than approximatively $10^7$ GeV: this
problem, and its possible solutions, are discussed.


title: Solution of gauge theories induced by fundamental representation scalars

abstract:
  Gauge theories induced by scalars in the fundamental representation of the
$U(N_c)_{gauge}\times U(N_f)_{global}$ group are investigated in the large
$N_c$ and $N_f$ limit. A master field is defined from bilinears of the scalar
field following an Eguchi-Kawai type reduction of spacetime. The density
function for the master field satisfies an integral equation that can be solved
exactly in two dimensions (D=2) and in a convergent series of approximations at
$D>2$. While at D=2 the system is in the same phase at all $\epsilon=N_c/N_f$,
it undergoes a phase transition at a critical value, $\epsilon_c(D)$, for
$D>2$.


title: Third Generation Familons, B Factories, and Neutrino Cosmology

abstract:
  We study the physics of spontaneously broken family symmetries acting on the
third generation. Massless familons (or Majorons) $f$ associated with such
broken symmetries are motivated especially by cosmological scenarios with
decaying tau neutrinos. We first note that, in marked contrast with the case
for the first two generations, constraints on third generation familon
couplings are poor, and are, in fact, non-existent at present in the hadronic
sector. We derive new bounds from $B^0$--$\bar{B}^0$ mixing, $B^0 \to l^+
l'^-$, $b\to s\nu\bar{\nu}$, and astrophysics. The resulting constraints on
familon decay constants are still much weaker than those for the first and
second generation. We then discuss the promising prospects for significant
improvements from searches for $\tau\to l f$, $B\to (\pi, K) f$, and $b\to
(d,s) f$ with the current CLEO, ARGUS, and LEP data. Finally, we note that
future constraints from CLEO III and the $B$ factories will probe decay
constants beyond 10^8 GeV, well within regions of parameter space favored by
proposed scenarios in neutrino cosmology.


title: A Covariant Light-Front Model of Heavy Mesons within HQET

abstract:
  In this paper we construct a covariant light-front model of heavy mesons
within the framework of heavy quark effective theory (HQET). The covariant
model consists of the light-front heavy meson bound states constructed in the
heavy quark limit with heavy quark symmetry and heavy quark effective theory as
its basis. Within this model, the Isgur-Wise function and decay constants in
the infinite quark mass limit can be evaluated in a very simple and the most
general way. The results are ensured to be consistent with heavy quark
symmetry. From the heavy-quark-limit bound states, we can further develop a
systematic approach to calculate $1/m_Q$ corrections from the $1/m_Q$ expansion
of QCD. This covariant model can serve as a quasi-first-principles description
of heavy meson dynamics, namely, a phenomenological covariant bound state in
the heavy quark limit which is consistent with heavy quark symmetry, plus a
reliable first-principles computation of the $1/m_Q$ corrections in HQET in
terms of the $1/m_Q$ expansion of the fundamental QCD theory.


title:
Report of the working group on the measurement of triple gauge boson
  couplings

abstract:
  The working group discussed several aspects of triple gauge coupling analysis
viewed in the light of experiences with the first high energy data recorded at
energies above the W pair threshold. Some analysis methods were reviewed
briefly, and consideration given to better ways of characterising the data. The
measurement of CP violating parameters was discussed. Results were prepared to
further quantify the precision attainable on anaomalous couplings in the
four-quark channel using jet-charge methods, and finally the trade off between
maximum LEP energy-vs-luminosity was quantified.


title: Studying Lepton Family Violation in Lepton-Lepton Collisions

abstract:
  In the context of the future high energy - high luminosity electron and muon
colliders, all the relevant four-lepton processes with the lepton family
violation (LFV) are systematically classified. The most general LFV effective
lagrangians are found, and the helicity differential cross sections for the LFV
processes are calculated. The six- and eight-lepton Standard Model (SM)
backgrounds are discussed, and the LFV processes clean of the six-lepton
background are picked out. The possibility to suppress the six-lepton SM
background, when present, by the unnatural initial beam polarizations is
investigated. It is shown that the four-lepton LFV processes are amenable to
experimental study in the lepton-lepton collisions in the most favourable cases
up to the underlying scale of order 100 TeV. Studying these processes should
provide an essential part of the physics program for the next generation lepton
colliders to unravel the outstanding flavour/family problem.


title: Effective Lagrangians and low energy photon-photon scattering

abstract:
  We use the behavior of the photon-photon scattering for photon energies
$\omega$ less than the electron mass, $m_e$, to examine the implications of
treating the Euler-Heisenberg Lagrangian as an effective field theory.
Specifically, we determine the $\omega^2/m_e^2$ behavior of the scattering
amplitude predicted by including one-loop corrections to the Euler-Heisenberg
effective Lagrangian together with the counterterms required by
renomalizability. This behavior is compared with the energy dependence obtained
by expanding the exact QED photon-photon scattering amplitude. If the
introduction of counterterms in the effective field theory is restricted to
those determined by renormalizability, the $\omega^2/m_e^2$ dependences of the
two expansions differ.


title: SO(10) Unified Theories and Cosmology

abstract:
  We review the status of a class of gauge unified models based on SO(10)
group. After a pedagogical introduction to SO(10) gauge theories, we discuss
the main phenomenological implications of these models. The upper limit on
proton lifetime are obtained and the prediction for neutrino masses are
compared with the astrophysical and cosmological constraints coming from solar
neutrino data and dark matter problem. Possible scenarios for the production of
the baryon asymmetry of the universe required by primordial nucleosynthesis are
also discussed.


title: Geometric Reheating after Inflation

abstract:
  Inflationary reheating via resonant production of non-minimally coupled
scalar particles with only gravitational coupling is shown to be extremely
strong, exhibiting a negative coupling instability for $\xi < 0$ and a wide
resonance decay for $\xi \gg 1$. Since non-minimal fields are generic after
renormalisation in curved spacetime, this offers a new paradigm in reheating -
one which naturally allows for efficient production of the massive bosons
needed for GUT baryogenesis. We also show that both vector and tensor fields
are produced resonantly during reheating, extending the previously known
correspondences between bosonic fields of different spins during preheating.


title:
The 3d Effective Field Theory for Finite Temperature Scalar
  Electrodynamics

abstract:
  The effective field theory approach to high temperature field theory can be
used to study the phase transition in theories with spontaneously broken
symmetry. I construct a sequence of two effective three--dimensional field
theories which are valid on successively longer distance scales for a specific
model: $N$ charged scalars coupled to a U(1) gauge field. The resulting
effective Lagrangian can be used to investigate the phase transition, in
particular the order of the phase transition as a function of $N$, using
lattice simulations.


title: QCD field strength correlator at the next-to-leading order

abstract:
  The gauge invariant two-point correlation function of the gauge field
strength tensor is calculated in perturbation theory at the next-to-leading
order. Besides a direct calculation in perturbative QCD we also present a
derivation of the correlation function in the heavy quark effective theory. Our
results are briefly compared with recent determinations of the field strength
correlator on the lattice.


title: Photon-neutrino interactions in magnetic fields

abstract:
  The low-energy two neutrino-two photon interactions in the presence of
homogeneous magnetic field are studied. The cross sections in external magnetic
field are shown to be larger than in vacuum by factor $\sim (m_W /m_e)
^4(B/B_c) ^2$. The energy-loss rate due to the process $\gamma \gamma \to \nu
\bar{\nu}$ in magnetic field is obtained.


title: Much ado about nothing: vacuum and renormalization on the light-front

abstract:
  In the first part of my lectures, I will use the example of deep-inelastic
scattering to explain why light-front coordinates play a distinguished role in
many high energy scattering experiments. After a brief introduction into the
concept of light-front quantization, I will show that the vacuum for any
light-front Hamiltonian is trivial, i.e. the same as for non-interacting
fields. In the rest of my lectures, I will discuss several toy models in 1+1
and 3+1 dimensions and discuss how effective light-front Hamiltonians resolve
the apparent paradox that results from having a trivial light-front vacuum.


title: Diffractive Mass Spectra at DESY-HERA in the Interacting Gluon Model

abstract:
  We have applied the Interacting Gluon Model (IGM) to calculate diffractive
mass spectra measured recently in e-p collisions at HERA. We show that it is
possible to treat them in terms of gluon-gluon collisions in the same way as
was done before for hadronic collisions. Analysis of available data is
performed.


title: Feynman Diagrams and Cutting Rules

abstract:
  We show how Feynman diagrams may be evaluated to take advantage of recent
developments in the application of Cutkosky rules to the calculation of
one-loop amplitudes. A sample calculation of gg->gH, previously calculated by
Ellis et al., is presented illustrating this equivalence. This example
demonstrates the use of cutting rules for massive amplitudes.


title: The Linked Dipole Chain Monte Carlo

abstract:
  We present an implementation of the Linked Dipole Chain model for deeply
inelastic ep scattering into the framework of the Ariadne event generator.
Using this implementation we obtain results both for the inclusive structure
function as well as for exclusive properties of the hadronic final state. (The
original publication was based on results from an implementation containing an
error. In this revised version this error has been corrected, some of the
beyond leading-log assumptions have been revised and so have some of the
results.)


title: Resolved Photons and BFKL-type Signatures in Deep Inelastic Scattering

abstract:
  The concept of resolved virtual photons in addition to direct deep inelastic
$ep$ scattering is used to simulate the 2+1 jet - rate and the forward jet
cross section, which cannot be described by direct LO/NLO processes. With
standard DGLAP evolution of the parton densities of the virtual photon and the
proton the HERA data can be described, provided a sufficiently large scale for
the hard scattering matrix element is used.


title: Electromagnetic processes and the diquark model

abstract:
  The present status of the diquark model for exclusive reactions at moderately
large momentum transfer is reviewed. That model is a variant of the
Brodsky-Lepage approach in which diquarks are considered as quasi-elementary
constituents of baryons. Recent applications of the diquark model, relevant to
high energy physics with electromagnetic probes, are discussed: electromagnetic
form factors of baryons in both the space-like and the time-like region,
two-photon annihilations into proton-antiproton pairs as well as real and
virtual Compton scattering.


title: Heavy quark production: recent developments

abstract:
  I discuss some aspects of the comparison between QCD predictions and
experimental data in charm and bottom production.


title: $\Delta S = 1$ Hadronic Weak Decays of Hyperons in a Soliton Model

abstract:
  We study the parity violating hyperon non-leptonic weak decays in the three
flavor Skyrme model. We follow the approach in which the symmetry breaking
terms in the action are diagonalized exactly within the collective coordinate
approximation. We show that although this method introduces some configuration
mixing, the $\Delta I =1/2$ rule is numerically well satisfied. In addition,
and in contrast to previous calculations, we show that not only the relative
amplitudes are in good agreement with the empirical values but also their
absolute values. The issue of whether the strong interaction enhancement
factors should be included in soliton calculations is also addressed.


title: Alpha_s: from DIS to LEP

abstract:
  The strong coupling alpha_s is a fundamental parameter of the Standard Model.
In comparison to parameters like alpha_em and M_Z it is relatively poorly
known. However the precision of alpha_s measurements has improved dramatically
in recent years. More than twenty different types of process, from lattice QCD
studies to the highest energy colliders, can be used to measure alpha_s
accurately. The most precise determinations now quote uncertainties in
alpha_s(M_Z) of less than 5%. There is also a remarkable consistency between
the various measurements. The present review provides an update on alpha_s
measurements from the past year.


title: Light Quark Masses in QCD

abstract:
  Invited talk given at the conference QCD97, Montpellier, France. I report on
rec ent work done in collaboration with Laurent Lellouch and Josep Taron
concerning the derivation of rigorous lower bounds for the combination of light
quark massese s m_s + m_u and m_d + m_u.


title:
Gauge-Mediated Supersymmetry Breaking Signals in an Electron-Photon
  Collider

abstract:
  We show the usefulness of an $e^-\gamma$ collider with backscattered laser
photons in unveiling the signatures of Gauge-Mediated Supersymmetry Breaking
models, with a right selectron as the next LSP. We also show how the signal can
be distinguished from the Standard Model background as well as from signals of
minimal supersymmetry.


title:
The Wilson renormalization group for low x physics: Gluon evolution at
  finite parton density

abstract:
  We derive the complete Wilson renormalization group equation which governs
the evolution of the gluon distribution and other gluonic observables at low
$x$ and arbitrary density.


title:
A BFKL Pomeron Manifestation in Inclusive Single Jet Production at
  High-Energy Hadron Collisions

abstract:
  A discrepancy between new data on inclusive single jet production at the
Fermilab Tevatron and perturbative QCD is discussed. It is shown that the
discrepancy may be accounted for by the BFKL Pomeron.


title: Thermodynamic Equations of State for Dirac and Majorana Fermions

abstract:
  The thermodynamic equations of state for Majorana and Dirac fermions are
quite different even in the limit of zero mass. The corresponding equations are
derived from general principles, and then applied to neutrinos. The nature of
the approach to equilibrium is explored, along with the subtleties of low or
zero mass neutrinos interacting via purely left-handed currents. Possible
applications to cosmology, supernovae, and supersymmetry are discussed.


title: Single-top production at future ep colliders

abstract:
  The production of top quarks in single mode at future ep colliders is
studied, the attention being mainly focused to the case of the proposed LEPXLHC
collider. We are motivated to reanalyse such a process following the discovery
of the top quark at Fermilab. Thanks to the measurement of its mass one is now
able to establish more accurately the relevance of single top production for
itself and for many other processes to which it may act as a background. In
addition, the recent improvement of our knowledge of the quark and gluon
dynamics inside the proton now allows one to pin down the dependence of single
top production on the partonic structure functions. Both the leptonic and
hadronic decay channels of the top quark are studied and compared to the yield
of the corresponding irreducible background in presence of b-tagging


title:
Nucleon structure functions from the instanton vacuum: Leading and
  non-leading twists

abstract:
  We review the description of nucleon structure functions in the instanton
vacuum. This includes the calculation of the twist-2 parton distributions at a
low normalization point as well as higher-twist matrix elements. The instanton
vacuum with its inherent small parameter, the packing fraction of the instanton
medium, $\bar\rho / R$, provides a consistent picture of the non-perturbative
gluon degrees of freedom at the scale $\bar\rho^{-1} \simeq 600 MeV$. The
twist-2 quark and antiquark distributions are of order unity, while the twist-2
gluon distribution is of order $(\bar\rho / R)^4$. Twist-4 matrix elements
determining power corrections to the Bjorken, Ellis-Jaffe and
Gross-Llewellyn-Smith sum rules are found to be of order $(\bar\rho / R)^0$. We
present numerical estimates for the parametrically large quantities.


title:
Effective Lagrangian Models for Gauge Theories of Fundamental
  Interactions

abstract:
  In this thesis we show that the effective Lagrangian models, encoding the
relevant symmetries of the underlying fundamental gauge theory for strong
interactions (QCD), provide a reasonable understanding of the interactions
among Light Mesons at intermediate energies as well as of the properties of
Heavy Baryons.


title: Up-Down Asymmetry: A Diagnostic for Neutrino Oscillations

abstract:
  We propose a simple test of underground neutrino data to discriminate amongst
neutrino oscillation models. It uses the asymmetry between downward-going
events and upward-going events, for electron and muon events separately.
Because of the symmetry of typical underground detectors, an asymmetry can be
compared with calculations with little need for the intermediary of a
simulation program. Furthermore, we show that the various oscillation scenarios
give rise to dramatically differing trajectories of asymmetry versus energy for
muons and electrons. This permits a clean distinction to be drawn between
models.


title:
Atmospheric neutrino oscillations with three neutrinos and a mass
  hierarchy

abstract:
  A comprehensive formalism for the description of neutrino oscillations in the
Earth in a general scheme with three massive neutrinos and the mass hierarchy
m_1<<m_2<<m_3 is presented. Using this formalism, which is valid both in vacuum
and in a medium, the matter effect on the oscillations of low-energy neutrinos
is discussed, pointing out the existence of very long oscillations which are
independent of the neutrino masses and the neutrino energy, and are very
sensitive to the matter density along the neutrino trajectory. As an example of
application of the formulation, a fit of the Kamiokande atmospheric neutrino
data with the matter effect taken into account for neutrinos propagating in the
Earth is presented. The results of the fit indicate that 4*10^{-3} eV^2 < m_3^2
< 4*10^{-2} eV^2 and the oscillation amplitudes in all channels (nu_mu<->nu_e,
nu_mu<->nu_tau, nu_e<->nu_tau) could be large. Hence, long-baseline experiments
with reactor (CHOOZ and Palo Verde) and accelerator (K2K, MINOS and ICARUS)
neutrinos could observe neutrino oscillations in all channels with a relatively
large statistics.


title: Charm in Deep Inelastic Scattering

abstract:
  We outline the existing descriptions of the charm component of the deep
inelastic proton structure function F2. We discuss recent approaches to include
charm mass effects in the parton evolution equations and the coefficient
functions.


title: Weak Decays, Quark Mixing and CP Violation: Theory Overview

abstract:
  A brief overview of flavour-changing phenomena is presented. The main topics
discussed are the universality and Lorentz structure of the leptonic
charged-current couplings, our present knowledge of the quark-mixing matrix and
the future prospects for CP--violation studies.


title:
An Ordered Analysis of Heavy Flavour Production in Deep Inelastic
  Scattering

abstract:
  At low Q^2, charm production in deep-inelastic scattering is adequately
described by assuming generation in electroweak boson-light parton scattering
(dominantly boson-gluon fusion) which naturally incorporates the correct
threshold behaviour. At high Q^2 this description is inadequate, since it does
not sum logs in Q^2/m_c^2, and is replaced by the treatment of the charm quark
as a light parton. We show how the problem of going from one description to the
other can be solved in a satisfactory manner to all orders. The key ingredient
is the constraint of matching the evolution of the physical structure function
F_2 order by order in alpha_s(Q^2) in addition to the matching of the value of
F_2 itself. This leads to new expressions for the coefficient functions
associated with the charm parton which are unique in incorporating both the
correct threshold and asymptotic behaviours at each order in perturbation
theory. The use of these improved coefficients lead to an improvement in global
fits and an excellent description of the observed F_2,charm.


title: Inflationary Reheating Classes via Spectral Methods

abstract:
  Inflationary reheating is almost completely controlled by the Floquet
indices, $\mu_k$. Using spectral theory we demonstrate that the stability bands
(where $\mu_k = 0$) of the Mathieu and Lam\'e equations are destroyed even in
Minkowski spacetime, leaving a fractal Cantor set or a measure zero set of
stable modes in the cases where the inflaton evolves in an almost-periodic or
stochastic manner respectively. These two types of potential model the expected
multi-field and quantum backreaction effects during reheating.


title: A Perturbative Gluon Condensate

abstract:
  There is considerable freedom in setting boundary conditions to perturbation
theory at $t=\pm\infty$. The standard PQED and PQCD expansions are based on the
(empty) perturbative vacuum. Since the true QCD ground state is expected to
have a condensate of low momentum gluons, I propose studying expansions around
states containing free particles. A specific boundary condition (the
`Perturbative Gluon Condensate'), which implies a freezing of low momentum
gluons, could be a candidate for describing confinement physics. The modified
perturbative series has a number of new features, although it is formally
equivalent to the standard one and a priori equally justified.


title: Neutralino Decay Rates with Explicit R-parity Violation

abstract:
  We compute the neutralino decay rate in the minimal supersymmetric standard
model with the addition of explicit R-parity violation. We include the complete
squark and slepton mixing matrices, previously neglected, and we improve and
correct published formulas. These decays are relevant to accelerator and
non-accelerator searches for R-parity violation, and are especially interesting
in light of the reported high Q^2 anomaly at HERA.


title:
The Sum Rules for Structure Functions of Polarized $e(\mu)N$ Scattering:
  Theory vs. Experiment

abstract:
  The determination of twist-4 corrections to the structure functions of
polarized $e(\mu)N$ scattering by QCD sum rules is reviewed and critically
analyzed. It is found that in the case of the Bjorken sum rule the twist-4
correction is small at $Q^2 > 5 GeV^2$. However, the accuracy of the today
experimental data is insufficient to reliably determine $\alpha_s$ from the
Bjorken sum rule. For the singlet sum rule -- $p+n$ -- the QCD sum rule gives
only the order of magnitude of twist-4 correction. At low and intermediate
$Q^2$ the model is presented which realizes a smooth connection of the
Gerasimov-Drell-Hearn sum rules at $Q^2 = 0$ with the sum rules for
$\Gamma_{p,n}(Q^2)$ at high $Q^2$. The model is in a good agreement with the
experiment.


title: T Violating Muon Polarization in $K^+\to \mu^+\nu\gamma$

abstract:
  We study the T violating transverse muon polarization in the decay of $K^+\to
\mu^+\nu\gamma$ due to CP violation in theories beyond the standard model. We
find that the polarization asymmetry could be large in some CP violation models
and it may be detectable at the ongoing KEK experiment of E246 as well as the
proposed BNL experiment.


title: Beautiful CP Violation

abstract:
  CP violation is observed to date only in K^0 decays and is parameterizable by
a single quantity epsilon. Because it is one of the least understood phenomena
in the Standard Model and holds a clue to baryogenesis, it must be investigated
further. Highly specialized searches in K^0 decays are possible. Effects in B
decays are much larger. In addition to the traditional B_d -> J/\psi K_S,
pi^+pi^- asymmetries, CP violation could be searched for in already existing
inclusive B data samples. The rapid B_s - B_s.bar oscillations cancel in
untagged B_s data samples, which therefore allow feasibility studies for the
observation of CP violation and the extraction of CKM elements with present
vertex detectors. The favored method for the extraction of the CKM angle gamma
is shown to be unfeasible and a solution is presented involving striking direct
CP violation in charged B decays. Novel methods for determining the B_s mixing
parameter Delta m are described without the traditional requirement of
flavor-specific final states.


title: Effective theories for real-time correlations in hot plasmas

abstract:
  We discuss the sequence of effective theories needed to understand the
qualitative, and quantitative, behavior of real-time correlators < A(t) A(0) >
in ultra-relativistic plasmas. We analyze in detail the case where A is a
gauge-invariant conserved current. This case is of interest because it includes
a correlation recently measured in lattice simulations of classical, hot,
SU(2)-Higgs gauge theory. We find that simple perturbation theory, free kinetic
theory, linearized kinetic theory, and hydrodynamics are all needed to
understand the correlation for different ranges of time. We emphasize how
correlations generically have power-law decays at very large times due to
non-linear couplings to long-lived hydrodynamic modes.


title: The Status of the Minimal Supersymmetric Standard Model and Beyond

abstract:
  The minimal supersymmetric extension of the Standard Model (MSSM) is
reviewed. In the most general framework with minimal field content and R-parity
conservation, the MSSM is a 124-parameter model (henceforth called MSSM-124).
An acceptable phenomenology occurs only at exceptional points (and small
perturbations around these points) of MSSM-124 parameter space. Among the
topics addressed in this review are: gauge coupling unification, precision
electroweak data, phenomenology of the MSSM Higgs sector, and supersymmetry
searches at present and future colliders. The implications of approaches beyond
the MSSM are briefly addressed.


title: Coherent Neutrino Propagation in a Dense Medium

abstract:
  Motivated by the effect of matter on neutrino oscillations (the MSW effect)
we have studied the propagation of neutrinos in a dense medium. The dispersion
relation for massive neutrinos in a medium is known to have a minimum at
nonzero momentum $p\sim G_F\rho/\sqrt{2}$. We have studied in detail the origin
and consequences of this dispersion relation for both Dirac and Majorana
neutrinos both in a toy model with only neutral currents and a single neutrino
flavour and in a realistic ``Standard Model'' with two neutrino flavours. For a
range of neutrino momenta near the minimum of the dispersion relation, Dirac
neutrinos are trapped by their coherent interactions with the medium. This
effect does not lead to the trapping of Majorana neutrinos.


title: Fracture functions from cut vertices

abstract:
  Using a generalized cut vertex expansion we introduce the concept of an
extended fracture function for the description of semi-inclusive deep inelastic
processes in the target fragmentation region. Extended fracture functions are
shown to obey a standard homogeneous DGLAP-type equation which, upon
integration over t, becomes the usual inhomogeneous evolution equation for
ordinary fracture functions.


title: Isospin violation in pion-nucleon scattering

abstract:
  We construct the complete effective chiral pion-nucleon Lagrangian in the
presence of virtual photons to one loop. As an application, we consider strong
and electromagnetic isospin violation for scattering of neutral pions off
nucleons. We show that for the scattering lengths these isospin violating terms
are of the same size as the purely hadronic ones. We also analyze
isospin-violating effects for the $\sigma$--term. These can be as large as 10%
for the absolute value but are negligible for the shift to the Cheng-Dashen
point.


title:
QCD corrections to charged current processes at the Next Linear
  Collider: CC10, CC11 and CC20 at O(alpha_s)

abstract:
  One-loop QCD corrections to the full gauge invariant set of electroweak
diagrams describing the charged current processes $e^+ e^- \to u \bar d \mu
\bar\nu_\mu$ (CC10), $e^+ e^- \to u \bar d e^- \bar\nu_e$ (CC20) and $e^+ e^-
\to u \bar d s \bar c$ (CC11) are computed. We compare the exact calculation
with a ``naive''approach to strong radiative corrections which has been widely
used in the literature and discuss the phenomenological relevance of QCD
corrections for NLC physics.


title: Deuteron Spin Structure Functions at Small Bjorken-x

abstract:
  We investigate polarized deuteron structure functions at small values of the
Bjorken variable, x < 0.1. In this region contributions from the coherent
interaction of diffractively excited hadronic states with both nucleons become
important. A proper treatment of this process requires an extension of the
Glauber-Gribov multiple scattering theory to include spin degrees of freedom.
In the kinematic domain of current fixed target experiments we observe that
shadowing effects in g_1d are approximately twice as large as for the
unpolarized structure function F_2d. Furthermore at x < 0.1 the tensor
structure function b_1 is found to receive significant contributions from
coherent double scattering.


title: Generalized polarizabilities and the chiral structure of the nucleon

abstract:
  We discuss the virtual Compton scattering reaction $e^-p\to e^-p\gamma$ at
low energies. We present results for the generalized polarizabilities of the
nucleon obtained in heavy baryon chiral perturbation theory at $O(p^3)$.


title: Calculation of the semileptonic decay width of the $\Lambda_b$ baryon

abstract:
  We extend the approach based on the light-cone expansion and the heavy quark
effective theory to the inclusive semileptonic decay of an unpolarized
$b$-flavored hadron. It is applied to calculate the semileptonic decay width of
the $\Lambda_b$ baryon and its ratio to that of the B meson. We obtain
$\Gamma_{SL}(\Lambda_b)= 51\pm 9 |V_{cb}|^2{ps}^{-1}$ and
$\Gamma_{SL}(\Lambda_b)/\Gamma_{SL}(B)= 1.052\pm 0.006$. From the latter, the
semileptonic branching fraction for $\Lambda_b$ is predicted to be $(8.7\pm
0.7)%$.


title:
Charged Higgs scalar production in single-top mode (and other) at future
  $ep$ colliders in the Minimal Supersymmetric Standard Model

abstract:
  We study charged Higgs boson production at future electron-proton colliders
in the framework of the Minimal Supersymmetric Standard Model. We focus our
attention to the case of single-top production and decay through the channel
$t\to bH^\pm$ and of vector-scalar fusion via $W^{\pm*} \Phi^*\to H^\pm$ (where
$\Phi=H,h$ and $A$). We consider the signature $H^\pm\to \tau\nu_\tau$ and
compare it to the irreducible background from Standard Model interactions. For
$M_{H^\pm}<m_t$, the $H^\pm$ signal is accessible through lepton universality
breaking if $M_A<100-120$ GeV at both low and large values of $\tan\beta$.
Furthermore, although the bulk of the production cross section comes from
single-top events, a sizable contribution due to vector-scalar-scalar
interactions should be observable at large $\tan\beta$, this possibly offering
some insights into the structure of the scalar sector of the theory. The
possibility of the CERN collider running in the LEPXLHC mode is considered in
detail


title:
Radiative and non radiative muon capture on the proton in heavy baryon
  chiral perturbation theory

abstract:
  We have evaluated the amplitude for muon capture by a proton, mu + p --> n +
nu, to O(p^3) within the context of heavy baryon chiral perturbation theory
(HBChPT) using the new O(p^3) Lagrangian of Ecker and Mojzis (E&M). We obtain
expressions for the standard muon capture form factors and determine three of
the coefficients of the E&M Lagrangian, namely, b_7, b_{19}, and b_{23}. We
describe progress on the next step, a calculation of the radiative muon capture
process, mu + p --> n + nu + gamma.


title: Lattice Calculations of Decay Constants

abstract:
  Lattice attempts to compute the leptonic decay constants of heavy-light
pseudoscalar mesons are described. I give a short historical overview of such
attempts and then discuss some current calculations. I focus on three of the
most important sources of systematic error: the extrapolation to the continuum,
the chiral extrapolation in light quark mass, and the effects of quenching. I
briefly discuss the ``bag parameters'' $B_B$ and $B_{B_s}$, and then conclude
with my expectations of the precision in decay constants and bag parameters
that will be possible in the next few years.


title: Schwinger's nonet mass formula revisited

abstract:
  We prove the validity of Schwinger's quartic nonet mass formula for a general
nonet structure with the isoscalar singlet mass being shifted from its
``ideal'' value. We apply this formula to the problem of the correct q\bar{q}
assignment for the scalar meson nonet. The results favor scalar isoscalar
singlet and isoscalar octet masses in the vicinity of 1 GeV and 1.45 GeV,
respectively. We explain the failure of Schwinger's formula for the
pseudoscalar meson nonet, and suggest a new version of this formula, modified
by the inclusion of the pseudoscalar decay constants, which holds with improved
accuracy for this nonet. We also rederive the new Gell-Mann-Okubo mass formula
3M^2(n\bar{n},I=1)+2M^2(s\bar{s})=4M^2(s\bar{n})+M^2(n\bar{n},I=0) (n=u,d),
suggested in our previous publications.


title: Magnetic Defects Signal Failure of Abelian Projection Gauges in QCD

abstract:
  Magnetically charged Abelian defects are shown to arise on most compact base
manifolds and in most Abelian projection gauges. They obey the Dirac
quantisation condition and give rise to homogeneous magnetic background fields.
The reasons for their occurrence are global failures of the procedure with
which gauge covariant operators are diagonalised or their eigenphases
extracted. Defects related to the former case are string-like; for the latter
case they resemble domain walls. Either configuration forms the generic case
and indicates a failure of gauge fixing as continuity and periodicity
properties of the functional space are changed. These results are first
obtained in canonically quantised QCD_{3+1} and path integral QCD_{2+1} on the
torus for the modified axial gauge which keeps only the eigenphases as
dynamical variables of the Wilson line in the x_3-direction. In the end, they
are extended to other gauges, dimensions and standard manifolds.


title:
Light-Front Hamiltonian Approach to the Bound-State Problem in Quantum
  Electrodynamics

abstract:
  This dissertation presents the first theoretical investigation of the Lamb
shift in a light-front hamiltonian approach: the dominant part of the splitting
between the 2S(1/2) and 2P(1/2) energy levels in hydrogen is calculated. Also
presented for the first time is an analytic calculation in a light-front
hamiltonian approach of the singlet-triplet spin splitting in the ground state
of positronium through fourth order in the fine-structure constant.


title: Quantum Chromodynamics and the Z-width

abstract:
  We show by explicit construction of an alternative theory for the strong
interactions that it cannot be distinguished from QCD by any of the usual
precision tests except on extending these theories to the full electroweak
theory, by the Z- particle width.


title: Finiteness of Soft Terms in Finite N=1 SUSY Gauge Theories

abstract:
  Recently proposed relations between the renormalization group functions of
the soft supersymmetry breaking terms and those of a rigid theory allow one to
consider a possibility of constructing a totally all loop finite N=1 SUSY gauge
theory, including the soft SUSY breaking terms. The requirement of finiteness,
which can be satisfied in previously constructed finite SUSY GUTs, imposes some
constraints on the SUSY breaking parameters which, in the leading order,
coincide with those originating from the supergravity and superstring-inspired
models. Explicit relations between the soft terms, which lead to a completely
finite theory in any loop order, are given.


title:
Leptonic Generation Mixing, Noncommutative Geometry and Solar Neutrino
  Fluxes

abstract:
  Triangular mass matrices for neutrinos and their charged partners contain
full information on neutrino mixing in a most concise form. Although the scheme
is general and model independent, triangular matrices are typical for reducible
but indecomposable representations of graded Lie algebras which, in turn, are
characteristic for the standard model in noncommutative geometry. The mixing
matrix responsible for neutrino oscillations is worked out analytically for two
and three lepton families. The example of two families fixes the mixing angle
to just about what is required by the Mikheyev-Smirnov-Wolfenstein resonance
oscillation of solar neutrinos. In the case of three families we classify all
physically plausible choices for the neutrino mass matrix and derive
interesting bounds on some of the moduli of the mixing matrix.


title:
Influence of $SU(2) \otimes U(1)$ singlet scalars on Higgs boson signal
  at LHC

abstract:
  We investigate a model of $SU(2) \otimes U(1)$ singlet scalars coupled to
Standard Model. We point out that for the case of maximal mixing between
singlet scalars and standard Higgs boson the Higgs boson production cross
section is smaller than the standard Higgs boson production by factor
$\frac{1}{N+1}$, where N is the number of singlet scalar scalars. For the case
of big mixing Higgs boson could be nonobservable at LHC. However, there is also
a possibility for the observation of scalar singlets at LHC. As a
quasirealistic example we discuss a supersymmetric $SU(2) \otimes U(1)$
electroweak model with an additional gauge singlet chiral superfield.


title: Decuplet Baryon Magnetic Moments in the Chiral Quark Model

abstract:
  We present calculations of the decuplet baryon magnetic moments in the chiral
quark model. As input we use parameters obtained in qualitatively accurate fits
to the octet baryon magnetic moments studied previously. The values found for
the magnetic moments of $\Delta^{++}$ and $\Omega^{-}$ are in good agreement
with experiments. We finally calculate the total quark spin polarizations of
the decuplet baryons and find that they are considerably smaller than what is
expected from the non-relativistic quark model.


title:
Heavy flavour contributions to the spin structure function g_1(x,Q^2)
  and the Bjorken sum rule

abstract:
  We discuss the order alpha_s^2 corrections to the longitudinal spin structure
function g_1(x,Q^2,m^2) which are due to heavy flavour contributions. Here Q
denotes the virtuality of the photon and m stands for the heavy flavour mass.
Since the exact heavy quark coefficient functions are not known yet we have
used the asymptotic forms which are strictly speaking only valid in the region
Q^2 >> m^2. However an analysis of the exact and asymptotic expressions for
F_2^{NLO}(x,Q^2,m^2) and g_1^{LO}(x,Q^2,m^2) reveals that the asymptotic forms
can be also used at smaller Q^2. It appears that for the region 0.01 < x < 0.1
the NLO charm quark component can become twice as large as in LO. However it is
still much smaller than g_1(x,Q^2) due to light parton contributions. This is
in contrast to the observations made for F_2(x,Q^2) at small x. Also the charm
quark contribution to the Bjorken sum rule turns out to be very small.


title: Sigma Signal for Hybrid Baryon Decay

abstract:
  We develop an ansatze of the sigma enhancement of the I=0, L=0 $\pi$-$\pi$
scattering amplitude as arising from a low-energy glueball pole. Using this
picture we estimate the $\pi^0\pi^0$ to $\pi^0$ branching ratio for the decays
of the Roper resonance, which we previously found to be a hybrid in our QCD sum
rule calculation. We find that the sigma decay might be a good signal for
gluonic components of hadrons.


title:
Reggeons in diffractive interactions in deep inelastic scattering at
  HERA

abstract:
  The "triple-Regge" analysis of subleading Reggeon contributions to the
diffractive structure function in DIS at HERA is presented. The recently
published data allow to estimate the only free parameter of the analysis
related to the ratio of the RRP and PPP couplings. The large value of this
ratio is prefered which is in agreement with analyses of soft hadronic
interactions. The role of the subleading Reggeons as well as pions for the fast
forward neutron production in diffractive processes is estimated. The forward
piN state production is also discussed.


title: The Scattering Theory of CP Violation

abstract:
  The mixing effects and the $CP(T)$--violating formalism for Kaon, B--mesons
and similar unstable oscillating systems, are recovered by means of a method
based on the properties of the complex singularities in the $S$--matrix theory
with unstable intermediate states. General $q^2$--dependent relations for
CP--asymmetries are then introduced.


title:
The solar neutrino problem after three hundred days of data at
  SuperKamiokande

abstract:
  We present an updated analysis of the solar neutrino problem in terms of both
Mikheyev-Smirnov-Wolfenstein (MSW) and vacuum neutrino oscillations, with the
inclusion of the preliminary data collected by the SuperKamiokande experiment
during 306.3 days of operation. In particular, the observed energy spectrum of
the recoil electrons from 8B neutrino scattering is discussed in detail and is
used to constrain the mass-mixing parameter space. It is shown that: 1) the
small mixing MSW solution is preferred over the large mixing one; 2) the vacuum
oscillation solutions are strongly constrained by the energy spectrum
measurement; and 3) the detection of a possible semiannual modulation of the 8B
\nu flux due to vacuum oscillations should require at least one more year of
operation of SuperKamiokande.


title: Gauged B-3L_tau and Radiative Neutrino Masses

abstract:
  If the minimal standard model of quarks and leptons is extended to include
just a righthanded partner to nu_tau, then the quantum number B-3L_tau can be
added as a gauge symmetry without the appearance of anomalies. A suitable
extension of the scalar sector allows one neutrino to have a seesaw mass, and
the other two to have radiative masses, with acceptable phenomenological values
for neutrino oscillations. The B-3L_tau gauge boson may be light and be
observable through its decay into tau^+ tau^-.


title: Two Higgs Doublet Model From Quasilocal Quark Interactions

abstract:
  Quark models with four-fermion interaction including derivatives of fields in
the strong coupling regime are used to implement composite-Higgs extensions of
the Standard Model. In this approach the dynamical breaking of chiral symmetry
occurs in two (or more) channels (near polycritical values for coupling
constants), giving rise to two (or more) composite Higgs doublets. Two types of
models are built for which Flavour Changing Neutral Currents (FCNC) are
naturally suppressed. In the first Model I the second Higgs doublet is regarded
as a radial excitation of the first one. In the second Model II the quasilocal
Yukawa interaction with Higgs doublets reduces at low energies to a
conventional local one where each Higgs doublet couples to a definite charge
current and its v.e.v. brings the mass either to up- or to down-components of
fermion doublets. For the special configuration of four-fermion coupling
constants the dynamical CP-violation in the Higgs sector appears as a result of
complexity of v.e.v. for Higgs doublets.


title:
Transverse Spin Dependent Drell Yan in QCD to $O(\alpha_s^2)$ at Large
  $p_T$ (I). Virtual Corrections and Methods for the Real Emissions

abstract:
  We investigate the role of the transverse spin dependence in Drell Yan lepton
pair production to NLO in QCD at parton level. In our analysis we deal with the
large $p_T$ distributions. We give very compact expressions for the virtual
$O(\alpha_s^2)$ corrections to the cross section and show that the
singularities factorize. The study is performed in the $\bar{MS}$ scheme in
Dimensional Regularization, and with the t'Hooft-Veltman prescription for
$\gamma_5$. A discussion of the structure of the real emissions is included,
and detailed methods for the study of these contributions are formulated.


title: Dark matter axions and caustic rings

abstract:
  Contents:
  1. The strong CP problem
  2. Dark matter axions
  3. The cavity detector of galactic halo axions
  4. Caustic rings in the density distribution of cold dark matter halos


title: The Anomalous Chromomagnetic Dipole Moment of the Top Quark

abstract:
  We calculate the one loop corrections to the chromomagnetic dipole moment of
the top quark in the framework of the Standard Model, the two Higgs doublet
model and the Minimal Supersymmetric Standard Model. In the Standard Model we
consider the QCD and the electroweak corrections generated by gluon and Higgs
boson exchanges, respectively. In the Minimal Supersymmetric Standard Model, we
calculate the SUSY- QCD corrections, including the mixing effects between the
stop coming from the left- and right-handed sectors. We obtain that the
Standard Model contribution is of the order of -0.004< delta kappa_g^t <
-0.001, and the values for diferents scenarios are of the order of -0.001 <
\delta \kappa_g^t < -0.01.


title: Effects of Massive Gluons on Quarkonia in Light-Front QCD

abstract:
  A constituent parton picture of hadrons with logarithmic confinement arises
naturally in light-front QCD when the hamiltonian is computed using a
perturbative renormalization group; however, rotational symmetry is not
manifest as a simple kinematic symmetry. Relevant operators must typically be
fine-tuned when a perturbative renormalization group is used, and in
light-front field theory such operators contain functions of longitudinal
momenta. We explore the possibility that a gluon mass operator with simple
longitudinal momentum dependence may improve approximate kinematic rotational
symmetry, as revealed by the potential between heavy quarks.


title:
Semi-Inclusive DIS: an explicit calculation in the Target Fragmentation
  Region

abstract:
  I present a calculation of the one particle deep inelastic cross section in
the target fragmentation region in (\phi^3)_6. The renormalized cross section
gets a large logarithmic correction whose coefficient is precisely the scalar
DGLAP kernel. The result is found to be consistent with an extended
factorization hypothesis and with infrared power counting.


title: The gluon contribution to the polarized structure function $g_2$

abstract:
  We compute the structure function $g_2$ for a gluon target in perturbative
QCD at order $\as$. We show that its first moment vanishes, as predicted by the
Burkhardt-Cottingham sum rule.


title:
A Heavy Higgs Can Give Strong First Order Electroweak Phase Transition
  in the Standard Model

abstract:
  The role of Higgs sector of the standard model in first order phase
transition is reexamined.It is found that a solution to the mass gap equations
exist which can be used in higher orders. This possible solution leads to a
transition which is found to be strongly first order and the ratio of the
critical scaler field and the critical temperature is about 1.2 for a Higgs of
mass around 400 GeV.This can explain baryogenesis.


title:
Testing maximal electron and muon neutrino oscillations with sub-GeV
  SuperKamiokande atmospheric neutrino data

abstract:
  Motivated by the Exact Parity Model and other theories, the hypothesis that
each of the known neutrinos oscillates maximally with a sterile partner has
been put forward as an explanation of the atmospheric and solar neutrino
anomalies. We provide detailed predictions for muon and electron flux ratios
induced in the Kamiokande and SuperKamiokande detectors by sub-GeV atmospheric
neutrinos. Several different, carefully chosen cuts on momentum and zenith
angle are proposed, emphasizing the role of up-down flux asymmetries.


title: The strange quark mass from scalar sum rules updated

abstract:
  The talk discusses preliminary results of an updated analysis of the strange
quark mass from the scalar current QCD sum rules [1]. In particular the role of
the scalar form factor which is a main ingredient in the analysis is especially
emphasised. The sources of the uncertainties in the sum rule determination are
briefly reviewed.


title: Ultra-high energy LSP

abstract:
  We argue that the lightest supersymmetric particles (LSP) can be produced
with extremely high energies $E\gsim 10^{10}$ GeV in the Universe at the
present epoch. Their most probable sources are decaying superheavy particles
produced by topological defects or as relic Big Bang particle. We discuss the
mechanisms of production of LSP at ultra-high energies (UHE) and the
interaction of the UHE LSP with matter. The most attention is given to the
neutralino as LSP, although the gluino is also considered as a phenomenological
possibility.


title: The Optical Analogue of CP Violation

abstract:
  The peculiar features of the mixing in the neutral pseudoscalar mesons
K0--antiK0 can be introduced by the analogy to the optical polarization. The
time-reversed not-invariant processes and the related phenomenon of
CP-nonconservation can be then joined to the dissipative effects which yield a
not vanishing imaginary part in the relevant propagation of electromagnetic
radiation in a medium. Thus, the propagation of the two transverse polarization
states can reproduce the peculiar asymmetries which are so common in the realm
of high energy particle physics.


title: Direct photons in Pb+Pb at CERN-SPS from microscopic transport theory

abstract:
  Direct photon production in central Pb+Pb collisions at CERN-SPS energy is
calculated within the relativistic microscopic transport model UrQMD, and
within distinctly different versions of relativistic hydrodynamics. We find
that in UrQMD the local momentum distributions of the secondaries are strongly
elongated along the beam axis initially. Therefore, the pre-equilibrium
contribution dominates the photon spectrum at transverse momenta above $\approx
1.5$ GeV. The hydrodynamics prediction of a strong correlation between the
temperature and radial expansion velocities on the one hand and the slope of
the transverse momentum distribution of direct photons on the other hand thus
is not recovered in UrQMD. The rapidity distribution of direct photons in UrQMD
reveals that the initial conditions for the longitudinal expansion of the
photon source (the meson ``fluid'') resemble rather boostinvariance than
Landau-like flow.


title: UV renormalons in QCD and their phenomenological implications

abstract:
  I report on some recent work done in collaboration with E. de Rafael on the
connection between ultraviolet renormalons in QCD and Nambu-Jona-Lasinio-like
Lagrangians as its effective description at low energies.


title: Power counting in exclusive quarkonium decays

abstract:
  Recent progress in the factorization of exclusive decays of heavy quarkonia
into long-distance and short-distance contributions is presented. The role of
higher Fock states and colour-octet contributions is outlined.


title: Massive Two-Loop Integrals and Higgs Physics

abstract:
  We describe in some detail the present features of an automatic loop
calculation program as well as the integration techniques that go into it. The
program, called XLOOPS 1.0, allows one to calculate massive one- and two-loop
Feynman diagrams in the Standard Model including their tensor structure. UV
divergences in UV divergent integrals are explicitly computed in dimensional
regularization. One-loop integrals are calculated analytically in d \neq 4
dimensions whereas two-loop integrals are reduced to two-fold integral
representations which the program evaluates numerically. We discuss Higgs decay
at the two-loop level as a first application of the novel integration
techniques that are incorporated into XLOOPS.


title: Getting at the CP Angles

abstract:
  In anticipation for intensive experimental effort on B physics, theorists
have introduced many ingenious ways to measure properties of the unitarity
triangle. We review some of these methods. We will be critical in the hope
that, if there is any defect in them, it can be remedied either theoretically
or experimentally.


title: Supersymmetric Q-balls as dark matter

abstract:
  Supersymmetric extensions of the standard model generically contain stable
non-topological solitons, Q-balls, which carry baryon or lepton number. We show
that large Q-balls can be copiously produced in the early universe, can survive
until the present time, and can contribute to dark matter.


title:
New Interactions in Top Quark Production and Decay at the Tevatron
  Upgrade

abstract:
  New interactions in top-quark production and decay are studied under the
conditions of the Tevatron upgrade. Studying the process q qbar --> t tbar -->
b mu nu tbar, it is shown how the lepton rapidity and transverse energy
distribution are modified by nonstandard modifications of the g-t-tbar and the
t-b-W vertex.


title: When do neutrinos cease to oscillate?

abstract:
  In order to investigate when neutrinos cease to oscillate in the framework of
quantum field theory, we have reexamined the wave packet treatment of neutrino
oscillations by taking different sizes of the wave packets of the particles
involved in the production and detection processes. The treatment is shown to
be considerably simplified by using the Grimus-Stockinger theorem which enables
us to carry out the integration over the momentum of the propagating neutrino.
Our new results confirm the recent observation by Kiers, Nussinov and Weiss
that a precise measurement of the energies of the particles involved in the
detection process would increase the coherence length. We also present a
precise definition of the coherence length beyond which neutrinos cease to
oscillate.


title: Determination of $M_b$ and $\alpha_s$ from the Upsilon System

abstract:
  The mass of the bottom quark (both the pole mass $M_b$ and the $\MSb$ mass
$m_b$) and the strong coupling constant $\alpha_s$ have been determined from
QCD moment sum rules for the $\Upsilon$ system. In the pole-mass scheme large
perturbative corrections resulting from coulombic contributions have been
resummed. The results of this analysis are: $M_b=4.60 \pm 0.02 \gev$,
$m_b(m_b)=4.13 \pm 0.06 \gev$ and $\alpha_s(M_Z)=0.119 \pm 0.008$.


title:
Rapidity Correlations and $\Delta G $ from Prompt Photon plus Jet
  Production in Polarized $pp$ Collisions

abstract:
  A study of prompt photon plus associated jet production is performed at
next-to-leading order (O($\alpha\alpha_s^2$)) in QCD at $\sqrt{S}=200-500$ GeV,
appropriate for the RHIC polarized $\vec{p}\vec{p}$ collider experiment.
Momentum correlations between the jet and photon are examined and the utility
of the process as a method for constraining the size and shape of the polarized
gluon density of the proton $\Delta G$ is examined.


title: Power Corrections and the Gaussian Form of the Meson Wave Function

abstract:
  The wave function of a light pseudoscalar meson is considered and
nonperturbative corrections as signaled by perturbation theory are calculated.
Two schemes are used, the massive gluon and the running coupling scheme. Both
indicate the presence of leading power corrections of ${\cal O}(b^2)$, whose
exponentiation leads to a Gaussian dependence of the wave function on the
impact parameter $b$. The dependence of this correction on the light cone
energy fractions of the quark and the antiquark is discussed and compared with
other models for the meson.


title: "Lattice-Free" Simulations of Topological Defect Formation

abstract:
  We examine simulations of the formation of domain walls, cosmic strings, and
monopoles on a cubic lattice, in which the topological defects are assumed to
lie at the zeros of a piecewise constant 1, 2, or 3 component Gaussian random
field, respectively. We derive analytic expressions for the corresponding
topological defect densities in the continuum limit and show that they fail to
agree with simulation results, even when the fields are smoothed on small
scales to eliminate lattice effects. We demonstrate that this discrepancy,
which is related to a classic geometric fallacy, is due to the anisotropy of
the cubic lattice, which cannot be eliminated by smoothing. This problem can be
resolved by linearly interpolating the field values on the lattice, which gives
results in good agreement with the continuum predictions. We use this procedure
to obtain a lattice-free estimate (for Gaussian smoothing) of the fraction of
the total length of string in the form of infinite strings: $f_\infty = 0.716
\pm 0.015$.


title: Proof of Factorization for Diffractive Hard Scattering

abstract:
  A proof is given that hard-scattering factorization is valid for
deep-inelastic processes which are diffractive or which have some other
condition imposed on the final state in the target fragmentation region.


title: THE Goals and Techniques of BTeV and LHC-B

abstract:
  BTeV and LHC-B are experiments being proposed to study $b$ and $c$ quark
decays in hadron-hadron collisions with the aims to look for new phenomena
beyond the Standard Model and to measure Standard Model parameters including
CKM elements and decay constants. The physics goals, required detection
techniques and simulations will be discussed.


title: Higgs Bosons Production with Photons at Lepton-Antilepton Colliders

abstract:
  By model independent way scalar and pseudoscalar neutral Higgs boson
production with photon in the tree process $\mu^+\mu^- \to H^0 \gamma$ are
considered.For the Standard Model and Minimal Supersymmetric Standard Model
cases numerical estimates are obtained.The model independent flavour changing
Higgs bosons production in the tree processes $e^+e^-,\mu^+e^- \to H^0_{fc}
\gamma$ is also considered.


title: A Next-to-Minimal Supersymmetric Model of Hybrid Inflation

abstract:
  We propose a model of inflation based on a simple variant of the NMSSM,
called $\phi$NMSSM, where the additional singlet $\phi$ plays the role of the
inflaton in hybrid (or inverted hybrid) type models. As in the original NMSSM,
the $\phi$NMSSM solves the $\mu$ problem of the MSSM via the VEV of a gauge
singlet $N$, but unlike the NMSSM does not suffer from domain wall problems
since the offending $Z_3$ symmetry is replaced by an approximate Peccei-Quinn
symmetry which also solves the strong CP problem, and leads to an invisible
axion with interesting cosmological consequences. The PQ symmetry may arise
from a superstring model with an exact discrete $Z_3 \times Z_5$ symmetry after
compactification. The model predicts a spectral index $n=1$ to one part in
$10^{12}$.


title: Soft-Gluon Resummation: a Short Review

abstract:
  I briefly summarize some general features of soft-gluon contribution to
inclusive cross-sections. The discussion includes the issue of soft-gluon
singularities in infrared- and collinear-safe observables. All-order
resummation and the ensuing varieties of QCD predictions are illustrated.


title:
Moriond '97 - Electroweak Interactions and Unified Theories - Conference
  Summary

abstract:
  A brief summary of the experimental results presented at the conference is
given.


title: Supersymmetric particle searches at LEP

abstract:
  Searches for supersymmetric particles performed at LEP 1 and LEP 2 are
reviewed. Using the MSSM with R-parity conservation as a reference model, the
various analyses are briefly described, and the results are presented in terms
of mass and coupling limits. Further implications of these results are
discussed, including lower limits on the mass of a neutralino LSP, assuming the
MSSM with GUT relations. Less conventional scenarii, among which those
involving R-parity violation, are also investigated.


title:
Searching for a heavy Higgs boson via the H --> l nu jj decay mode at
  the CERN LHC

abstract:
  The discovery of a heavy Higgs boson with mass up to m_H = 1 TeV at the CERN
LHC is possible in the H--> W^+W^- --> l nu jj decay mode. The weak boson
scattering signal and backgrounds from t\bar tjj and from W+jets production are
analyzed with parton level Monte Carlo programs which are built on full tree
level amplitudes for all subprocesses. The use of double jet tagging and the
reconstruction of the W invariant mass reduce the combined backgrounds to the
same level as the Higgs signal. A central mini-jet veto, which distinguishes
the different gluon radiation patterns of the hard processes, further improves
the signal to background ratio to about 2.5:1, with a signal cross section of 1
fb. The jet energy asymmetry of the W --> jj decay will give a clear signature
of the longitudinal polarization of the W's in the final event sample.


title: Theory of Rare B Decays

abstract:
  We discuss some selected topics in rare B decays in the context of the
standard model and compare theoretical estimates with available data. Salient
features of the perturbative-QCD and power corrections in the decay rate for $B
\to X_s + \gamma$ are reviewed and this framework is used to determine the
Cabibbo-Kobayashi-Maskawa (CKM) matrix element $| V_{ts} |$. We review
estimates of the ratio $R_{K^*} \equiv \Gamma(B \to K^* + \gamma)/\Gamma(B \to
X_s + \gamma)$ in a number of theoretical models, which give a consistent
account of this quantity. Issues bearing on the photon energy spectrum in $B
\to X_s + \gamma$ are also discussed. The CKM-suppressed decays $B \to X_d +
\gamma$, $B^\pm \to \rho^\pm + \gamma$, and $B^{0} \to (\rho^{0}, \omega) +
\gamma$ are reviewed with particular emphasis on the long-distance
contributions in the exclusive decays. The impending interest in these decays
in determining the parameters of the CKM matrix is emphasized. Finally, the
semileptonic decays $B \to X_s \ell^+ \ell^-$ are also discussed in the context
of the SM.


title: Inelastic Rescattering and CP Asymmetries in D -> pi+ pi-, pi0 pi0

abstract:
  We study the direct CP violation induced by inelastic final state interaction
(FSI) rescattering in $D\to\pi\pi$ modes, and find that the resultant CP
asymmetry is about $10^{-4}$ which is larger than $\epsilon'$ in the K-system.
Our estimation is based on well-established theories and experiment measured
data, so there are almost no free parameters except the weak phase
$\delta_{13}$ in the CKM matrix.


title:
The QCD analysis of the revised CCFR data for xF_3 structure function:
  the next-to-next-to-leading order and Pad\'e approximants

abstract:
  The next-to-next-to-leading order (NNLO) QCD analysis of the revised
experimental data of the CCFR collaboration for the $xF_3$ structure function
of the deep-inelastic scattering of neutrinos and antinuetrinos on the nucleons
is made by means of the Jacobi polynomial expansion technique. The NNLO values
of the QCD coupling constant are determined both without and with twist--4
contributions taken into account. Theoretical ambiguities of $\alpha_s$ are
fixed using the methods of the Pad\'e approximants. We observe that the [0/2]
Pad\'e approximant is more appropriate for this purpose than the [1/1] one.


title: Modular Weights, U(1)'s and Mass Matrices

abstract:
  We derive the scalar mass matrices in effective supergravity models augmented
by a $U(1)_F$ family symmetry. Simple relations between $U(1)_F$ charges and
modular weights of the superfields are derived and used to express the matrices
with a minimum number of parameters. The model predicts a branching ratio for
the $\mu\to e\gamma$ process close to the present experimental limits.


title: An Unusual Signal for Supersymmetry at the Tevatron

abstract:
  We propose a new scenario in which the dominant signal for supersymmetry at
the Tevatron are the events having two or three $\tau$ leptons with high $p_T$
accompanied by large missing transverse energy. This signal is very different
from the multijet or multileptons (involving $e$ and/or $\mu$ only) or the
photonic signals that have been extensively investigated both theoretically and
experimentally. A large region of the GMSB parameter space with the lighter
stau as the NLSP allow this possibility. Such a signal may be present in the
past Tevatron data to be analyzed.


title:
Spontaneous Discrete Symmetry Breaking During Inflation and the NMSSM
  Domain Wall Problem

abstract:
  The Next to Minimal Supersymmetric Standard Model (NMSSM), proposed as a
solution of the mu problem of the Minimal Supersymmetric Standard Model, has a
discrete Z_{3} symmetry which is spontaneously broken at the electroweak phase
transition, resulting in a cosmological domain wall problem. In most cases this
domain wall problem cannot be solved by explicit Z_{3} breaking without
introducing supergravity tadpole corrections which destabilize the weak scale
hierarchy. Here we consider the possibility of solving the domain wall problem
of the NMSSM via spontaneous discrete symmetry breaking occuring during
inflation. For the case where the discrete symmetry breaking field has
renormalizible couplings to the NMSSM fields, we find that the couplings must
be less than 10^{-5} if the reheating temperature is larger than 10^{7}GeV, but
can be up to 10^{-3} for reheating temperatures of the order of the electroweak
phase transition temperature. For the case of non-renormalizible couplings, we
present a model which can solve the domain wall problem for large reheating
temperatures without requiring any very small coupling constants.
  In this model the domain walls are eliminated by a pressure coming from their
interaction with a coherently oscillating scalar field whose phase is fixed
during inflation.
  This oscillating scalar field typically decays after the electroweak phase
transition but before nucleosynthesis, leaving no additional
  Z_{3} symmetry breaking in the zero-temperature theory.


title: ``Electromagnetic'' Contributrion to the Nucleon Spin

abstract:
  A possible resolution to the question of where the nucleon gets some portion
of its internal angular momentum, not carried by the valence quarks, is given
in terms of the electromagnetic field angular momentum of the nucleon. This
field angular momentum is similiar in origin to that of the Thomson dipole (an
electric charge and a magnetic monopole), but arises from the interaction of
the quark electric charges and magnetic dipoles. Rough, order of magnitude
calculations show that such a field angular momentum could provide some of the
nucleon's spin. Under certain assumptions QCD should also exhibit a similiar
field angular momentum coming from the interaction of color charges with color
magnetic dipoles.


title: Gamma-beam propagation in the anisotropic medium

abstract:
  Propagation of gamma-beam in the anisotropic medium is considered. The
simpliest example of such a medium of the general type is a combination of the
two linearly polarized monochromatic laser waves with different frequencies
(dichromatic wave). The optical properties of this combination are described
with the use of the permittivity tensor. The refractive indices and
polarization characteristics of normal electromagnetic waves propagating in the
anisotropic medium are found. The relations, describing variations of
gamma-beam intensity and Stokes parameters as functions of propagation length
are obtained. The influence of laser wave intensity on the propagation process
are calculated.
  The gamma-beam intensity losses in the dichromatic wave depend on the initial
circular polarization of gamma-quanta. This effect is also applied to the
single crystals, which are oriented in some regions of coherent pair
production. In principle, the single crystal sensitivity to a circular
polarization can be used for determination of polarization of high energy (in
tens GeV and more) gamma-quanta and electrons.


title: Soft photons and hard thermal loops

abstract:
  We calculate within the Hard Thermal Loop expansion the production rate of
soft photons and lepton pairs by a hot quark-gluon plasma at thermal
equilibrium, up to the 2-loop order. Strong collinear divergences appear to mix
the orders of the perturbative expansion so that the 2-loop order is in fact
dominant compared to the 1-loop order. More precisely, angular integrals that
would otherwise be of order 1 are found to behave as powers of $1/g$ when the
produced photon is massless, therefore breaking the standard HTL power counting
rules.


title:
Millimetre-Range Forces in Superstring Theories with Weak-Scale
  Compactification

abstract:
  We show that theories in which supersymmetry is broken via Scherk-Schwarz
compactification at the weak scale, possess at least one scalar particle with
Compton wavelength in the millimetre range, which mediates a force with
strength 1/3 of gravity. Such forces are going to be explored in upcoming
experiments using micro-electromechanical systems or cantilever technology. We
also present a simple way of understanding some decoupling aspects of these
theories by analogy with finite-temperature field theory.


title: Target Fragmentation and Fracture Functions

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.


title: eta and eta' in a coupled Schwinger-Dyson and Bethe-Salpeter approach

abstract:
  Extending our earlier treatments of pi0, eta_c and eta_b, we study the
eta-eta' system and its gamma-gamma decays using a model which is a leading
version of the consistently coupled Schwinger-Dyson (SD) and Bethe-Salpeter
(BS) approach. The electromagnetic interactions are incorporated through a
(generalized) impulse approximation consistent with this bound-state approach,
so that the Ward-Takahashi identities of QED are preserved when quarks are
dynamically dressed. To overcome some of the limitations due to the ladder
approximation, we introduce a minimal extension to the bound--state approach
employed, so that the U_A(1) problem is avoided. Pointing out which of our
predictions hold in the coupled SD-BS approach in general, and which are the
consequences of the specific, chosen model, we present the results for the
axial-current decay constants of eta_8, eta_0, and of their physical
combinations eta and eta', the results for the gamma-gamma decay constants of
eta_0 and eta_8, for the two-photon decay widths of eta and eta', and for the
mixing-independent R-ratio constructed from them.


title:
Pulsar Velocity with Three-Neutrino Oscillations in Non-adiabatic
  Processes

abstract:
  We have studied the position dependence of neutrino energy on the
Kusenko-Segr\`{e} mechanism as an explanation of the proper motion of pulsars.
The mechanism is also examined in three-generation mixing of neutrinos and in a
non-adiabatic case. The position dependence of neutrino energy requires the
higher value of magnetic field such as $B\sim 3\times 10^{15}$ Gauss in order
to explain the observed proper motion of pulsars. It is shown that possible
non-adiabatic processes decrease the neutrino momentum asymmetry, whereas an
excess of electron neutrino flux over other flavor neutrino fluxes increases
the neutrino momentum asymmetry. It is also shown that a general treatment with
all three neutrinos does not modify the result of the two generation treatment
if the standard neutrino mass hierarchy is assumed.


title: Hard Thermal Loops and Chiral Lagrangians

abstract:
  Chiral symmetry is used as the guiding principle to derive hard thermal loop
effects in chiral perturbation theory. This is done by using a chiral invariant
background field method for the non-linear sigma model and the
Wess-Zumino-Witten lagrangian, with and without external vector and axial
vector sources. It is then shown that the n-point hard thermal loop is the
leading thermal correction for the Green function of n point vector soft quark
currents.


title:
Bounds on long-baseline nu_e->nu_e and nu_mu->nu_e transition
  probabilities

abstract:
  We discuss long-baseline neutrino oscillations in the framework of the two
4-neutrino schemes which can accommodate all existing neutrino oscillation
data. Negative results of short-baseline reactor and accelerator experiments
allow to obtain rather strong bounds on the long-baseline nu_e->nu_e and
nu_mu->nu_e transition probabilities. We consider in detail matter effects and
show that the vacuum bounds are not substantially modified. We also comment on
corresponding bounds in 3-neutrino scenarios.


title: The physics potential of the LHC

abstract:
  This talk is a short overview of the physics potential of the LHC with
emphasis on Higgs search and SUSY search. First I review why LHC with the ATLAS
and CMS detectors is expected to give a decisive test of the electroweak
symmetry breaking mechanism of the Standard Model. Then I consider the Higgs
sector of the Standard Model (SM). Finally the search for supersymmetry is
discussed within the framework of various implementation of the Minimal
Supersymmetric Standard Model (MSSM).


title: Hard Diffractive Scattering

abstract:
  I discuss hard diffractive scattering in the framework of perturbative QCD
and Regge-parametrization.


title: Light Quark Mass Determinations from the Lattice

abstract:
  This paper is a review of recent lattice determinations of the light quark
masses. It describes the method employed to calculate quark masses in the
lattice formulation, and the extrapolations required to reach the physical
regime. This review is designed to be accessible to a general audience, not
specifically lattice theorists.


title: Antenna Factorization of Gauge-Theory Amplitudes

abstract:
  I derive a single factorization formula which summarizes all soft and
collinear divergences of a tree-level gauge theory amplitude. The singular
factor squared is in a certain sense the generalization of the Catani-Seymour
dipole factorization formula.


title:
Two-loop Analysis of Axialvector Current Propagators in Chiral
  Perturbation Theory

abstract:
  We perform a calculation of the isospin and hypercharge axialvector current
propagators to two loops in SU(3)xSU(3) chiral perturbation theory. A large
number of order p^6 divergent counterterms are fixed, and complete two-loop
renormalized expressions for the pion and eta masses and decay constants are
given. The calculated isospin and hypercharge axialvector polarization
functions are used as input in new chiral sum rules, valid to second order in
the light quark masses. Some phenomenological implications of these sum rules
are considered.


title:
Model independent analysis of the trilinear gauge boson couplings at LC:
  role of polarized cross sections

abstract:
  By means of a model-independent analysis, we discuss the constraints on
anomalous trilinear gauge-boson couplings that can be obtained from the study
of electron-positron annihilation into $W$ pairs at LC with \sqrt{s}=0.5 TeV
and 1 TeV. We consider the general CP conserving anomalous effective
Lagrangian, as well as some specific models with reduced number of independent
couplings. The analysis is based on combinations of observables with initial
and final state polarizations, that allow to separately constrain the different
couplings and to improve the corresponding numerical bounds.


title:
Measurement of the form-factor ratios for D^+ -> \overline
  K^{*0}e^+\nu_e

abstract:
  We present a measurement of the form-factor ratios r_V=V(0)/A_1(0) and
r_2=A_2(0)/A_1(0) for the decay D^+ -> \overline K^{*0} e^+ \nu_e. The
measurement is based on a signal of approximately 3000 $D^+ -> \overline K^{*0}
e^+ \nu_e, \overline K^{*0} -> K^-\pi^+$ decays reconstructed in data from
charm hadroproduction experiment E791 at Fermilab. The results are r_V = 1.84
+- 0.11 +- 0.08 and r_2 = 0.71 +- 0.08 +- 0.09.


title:
Three-body decays of selectrons and smuons in low-energy supersymmetry
  breaking models

abstract:
  In models with low-energy supersymmetry breaking, it is well-known that
charged sleptons can be significantly lighter than the lightest neutralino,
with the gravitino and lighter stau being the lightest and next-to-lightest
supersymmetric particles respectively. We give analytical formulas for the
three-body decays of right-handed selectrons and smuons into final states
involving a tau, a stau, and an electron or muon, which are relevant in this
scenario. We find that the three-body decays dominate over much of the
parameter space, but the two-body decays into a lepton and a gravitino can
compete if the three-body phase space is small and the supersymmetry-breaking
scale (governing the two-body channel) is fairly low. We study this situation
quantitatively for typical gauge-mediated supersymmetry breaking model
parameters. The three-body decay lengths are possibly macroscopic, leading to
new unusual signals. We also analyze the final-state energy distributions, and
briefly assess the prospects for detecting these decays at CERN LEP2 and other
colliders.


title: R-Invariant Unification with Dynamical Higgs Multiplets

abstract:
  We construct R-invariant grand unification models with composite Higgs
multiplets. Higgs doublets are massless due to the R symmetry, which is not
spontaneously broken at the unification scale, while Higgs triplets get large
masses from a dynamically generated superpotential, which is allowed by an R
anomaly.


title:
Neutrino transitions nu -> nu gamma, nu -> nu e+ e- in a strong magnetic
  field as a possible origin of cosmological gamma-burst

abstract:
  The high energy neutrino transitions with the photon and electron-positron
pair creation in a strong magnetic field in the framework of the Standard Model
are investigated. The process probabilities and the mean values of the neutrino
energy and momentum loss are presented. The asymmetry of outgoing neutrinos, as
a possible source of sufficient recoil ``kick'' velocity of a remnant and the
emission of e+ e- pairs and gamma-quanta in a ``polar cap'' region of a
remnant, as a possible origin of cosmological gamma-burst are discussed.


title: CP-odd Anomalous W-boson Couplings from Supersymmety

abstract:
  The supersymmetric standard model contains a new CP-violating phase in the
mass matrices for charginos and neutralinos, which could induce CP-odd
anomalous couplings for the WWZ and WW\gamma vertices at the one-loop level. We
study these couplings, paying attention to the model-parameter and q^2
dependencies. It is shown that the CP-odd form factors could have values of
order 10^{-3}-10^{-4}, which are much larger than those predicted by the
standard model. We also discuss the possibility of examining these form factors
in experiments.


title:
Deviations from Low-energy Theorem for $V_L V_L$ Scattering due to
  Pseudo-Goldstone Bosons

abstract:
  Possible deviations from a low-energy theorem for the scattering of strongly
interacting longitudinally polarized $W$ and $Z$ bosons are discussed within a
particular scheme of electroweak symmetry breaking. The scheme (suggested
earlier by other authors in a slightly different context) is based on
spontaneous breakdown of a SU(4) symmetry to custodial SU(2) subgroup. The
physical spectrum of such a model contains a set of relatively light
pseudo-Goldstone bosons whose interactions with vector bosons modify the
low-energy theorem proven for a ``minimal'' symmetry-breaking sector. The
Goldstone-boson manifold $SU(4)/SU(2)$ is not a symmetric space. In this
context it is observed that, on the other hand, there is a large class of
models of electroweak symmetry breaking, involving groups $G$ and $H$ such that
the $G/H$ is a symmetric space and the corresponding rich multiplets of
pseudo-Goldstone bosons do not influence the canonical low-energy theorem. For
the scheme considered here, the relevant interactions are described in terms of
an effective chiral Lagrangian and tree-level contributions of the
pseudo-Goldstone boson exchanges to the vector boson scattering are computed
explicitly. A comparison with the Standard Model is made.


title: Towards Automatic Analytic Evaluation of Diagrams with Masses

abstract:
  A method to calculate two-loop self-energy diagrams of the Standard Model is
demonstrated. A direct physical application is the calculation of the two-loop
electroweak contribution to the anomalous magnetic moment of the muon
${{1/2}(g-2)}_{\mu}$. Presently, we confine ourselves to a ``toy'' model with
only $\mu$, $\gamma$ and a heavy neutral scalar particle (Higgs). The algorithm
is implemented as a FORM-based program package. For generating and
automatically evaluating any number of two-loop self-energy diagrams, a special
C-program has been written. This program creates the initial FORM-expression
for every diagram generated by QGRAF, executes the corresponding subroutines
and sums up the final results.


title:
Single spin asymmetries from a gluonic background in the Drell-Yan
  process

abstract:
  We discuss the effects of so-called gluonic poles in twist-three hadronic
matrix elements, as first considered by Qiu and Sterman, in the Drell-Yan
process. These effects cannot be distinguished from those of time-reversal odd
distribution functions, although time-reversal invariance is not broken by the
presence of gluonic poles. Both gluonic poles and time-reversal odd
distribution functions can lead to the same single spin asymmetries. We
explicitly show the connection between gluonic poles and large distance gluon
fields, identify the possible single spin asymmetries in the Drell-Yan process
and discuss the role of intrinsic transverse momentum of the partons.


title: The $Q^2$ evolution of Soffer inequality

abstract:
  DGLAP evolution equations may be presented in a form completely analogous to
the Boltzmann equation. This provides a natural proof of the positivity of the
spin-dependent parton distributions, provided the initial distributions at
$Q^2_0$ are also positive. In addition, the evolution to $Q^2 < Q^2_0$ may
violate positivity, providing therefore a 'time arrow'. The positivity
condition is just $|\Delta P_{ij} (z)| \leq P_{ij} (z) $ for $z < 1$ for all
types of partons, while the $'+'$prescription and terms containing
$\delta(1-z)$ do not affect positivity. This method allows one to complete
immediately the existing proof of Soffer inequality at leading and
next-to-leading order.


title: On the top-quark polarization and how to measure it

abstract:
  The top quark is expected to decay as a free particle with definite momentum
and polarization. Here we consider the possibilities to obtain information
about its polarization through the energy and angular distributions of the
b-quarks from the decay of the top-quarks produced in $e^+e^-$ annihilation.
Analytic expressions and numerical estimates for different beam polarizations
are derived.


title: Ward-Takahashi Identidy on the Ligth-Front

abstract:
  The Ward-Takahashi identity, reflecting local gauge invariance, is
perturbatively verified for a boson model in light front field theory. A
careful integration over the light front energy, corresponding to exactly
taking into account pair terms, which are the contributions of the zero
longitudinal momentum mode, is crucial to obtain this result. Furthermore, the
one-loop boson form factors are calculated for arbitrary off-shell momenta.


title: $\chi_{c J}$ production in $e^+e^-$ annihilation

abstract:
  Inclusive production of $\chi_{c J}$ in $e^+e^-$ annihilation is an excellent
probe of the role of higher Fock states in the production of heavy quarkonia.
Within the non-relativistic QCD approach, contributions from the short-distance
production of colour-octet $c\bar{c}$ pairs are significantly larger than those
from colour-singlet production. At the same time, $\chi_{c J}$ production rates
are significantly smaller than expected in the colour evaporation approach.
Measurements of $\chi_{\c J}$ production at CLEO and future B-factories will
thus constitute a major test of theoretical approaches to the production of
heavy quarkonia.


title: Pion Eletromagnetic Current in the Ligth-Cone Formalism

abstract:
  The electromagnetic form factor of the pion is calculated in a pseudoscalar
field theoretical model which constituent quarks. We extract the form factor
using the "+" component of the electromagnetic current in the light-cone
formalism. For comparison, we also compute the form factor in the covariant
framework and we obtain perfect agreement. It is shown that the pair terms do
not contribute in this pseudoscalar model. This explains why a naive light-cone
calculation, i.e., omitting pair terms from the onset, also yields the same
results.


title: Z' Investigations at Future Lepton Colliders

abstract:
  In this talk I summarize the capability of future lepton colliders to
indirectly discover a new $Z'$ and to determine its couplings to the fermions
of the Standard Model. The physics associated with sitting on the $Z'$-pole is
also briefly discussed. This analysis is based on the results presented in the
Snowmass 1996 New Gauge Boson Working Group report.


title: Domain wall solution for vector like model

abstract:
  Domain wall solution for $N_{c}=N_{f}$ supersymmetric QCD is constructed.
Astrophysical implications of the domain wall configuration is also discussed.


title:
Correlation between Confinement and Chiral-Symmetry Breaking in the Dual
  Higgs Theory

abstract:
  We study the correlation between confinement and dynamical chiral-symmetry
breaking (D$\chi$SB) in the dual Ginzburg-Landau (DGL) theory using the
effective potential formalism. The DGL theory is an infrared effective theory
based on the dual Higgs mechanism, and provides the nonperturbative gluon
propagator, which leads to the linear quark potential. The screening effect for
the confining potential can be obtained by introducing the infrared cutoff
corresponding to the hadron size. We formulate the effective potential for
D$\chi$SB in the DGL theory, and find the vacuum instability against quark
condensation. To extract confinement effect, we separate the effective
potential into the confinement part and others by dividing the confinement term
from other terms in the gluon propagator in the DGL theory. The confinement
part provides the dominant contribution to D$\chi$SB, which is regarded as
monopole dominance for D$\chi$SB. The relevant energy for D$\chi$SB is found to
be the infrared region below 1GeV. Monopole dominance for the DGL propagator is
also found in the intermediate region, 0.2fm $\simle r \simle$ 1fm.


title: 1-loop corrections to the SU(3) symmetric chiral soliton

abstract:
  Masses of the SU(3) chiral soliton in tree approximation turn out at much too
high energies typically around 2 GeV. It is shown that 1-loop corrections
reduce this value drastically with results in the region of the empirical
nucleon mass.


title: Charged Higgs Sector with and without R--Parity

abstract:
  The simplest way of studying systematically R-parity violating phenomena is
by introducing a bilinear term in the superpotential of the type $\epsilon\hat
L\hat H_2$, which violates R-parity and lepton number but keep barion number
conserved. In its simplest version, this ``$\epsilon$--model'' is a two
parameter extension of the MSSM and a one parameter extension of the
MSSM--SUGRA. Here we study the charged Higgs sector of the model, which mixes
with the stau sector, and compare it with the charged Higgs sector of the MSSM.
We demonstrate that $m_{H^{\pm}}$ can be lower than $m_W$ already at tree
level, and calculate the production cross section of pairs of charged Higgs and
staus. In this model it is possible the mixed production of a charged Higgs and
a stau and its production cross section can be sizable. We finally comment
about the new R-parity violating decay modes of the charged scalars.


title: Primordial Hypermagnetic Fields and Triangle Anomaly

abstract:
  The high-temperature plasma above the electroweak scale $\sim 100$ GeV may
have contained a primordial hypercharge magnetic field whose anomalous coupling
to the fermions induces a transformation of the hypermagnetic energy density
into fermionic number. In order to describe this process, we generalize the
ordinary magnetohydrodynamical equations to the anomalous case. We show that a
not completely homogeneous hypermagnetic background induces fermion number
fluctuations, which can be expressed in terms of a generic hypermagnetic field
configuration. We argue that, depending upon the various particle physics
parameters involved in our estimate (electron Yukawa coupling, strength of the
electroweak phase transition) and upon the hypermagnetic energy spectrum,
sizeable matter-antimatter fluctuations can be generated in the plasma. These
fluctuations may modify the predictions of the standard Big Bang
nucleosynthesis (BBN). We derive constraints on the magnetic fields from the
requirement that the homogeneous BBN is not changed. We analyse the influence
of primordial magnetic fields on the electroweak phase transition and show that
some specific configurations of the magnetic field may be converted into net
baryon number at the electroweak scale.


title: Nuclear shadowing and rho photoproduction

abstract:
  Rho photoproduction on complex nuclei is re-examined using a generalised
vector dominance model which succesfully predicts the observed nuclear
shadowing in real photoabsorption and deep inelastic scattering. This model is
shown to give a good fit to rho photoproduction data on both nucleons and
complex nuclei, in which the well-known disagreement between the measured
gamma-rho coupling and the gamma-rho coupling required by the simple vector
dominance model is eliminated. The rho N total cross-sections required are
similar to those predicted by the additive quark model; and the magnitude of
the correction to simple vector dominance is consistent with that inferred from
the analysis of real photoabsorption and deep inelastic scattering.


title:
How Devious are Deviations From Quantum Mechanics: The Case of the B^0
  \bar B^0 System

abstract:
  Considering semileptonic decays of the entangled B^0 \bar B^0 state which is
generated in the decay of Upsilon(4S), we simply multiply the
quantum-mechanical interference term by a factor (1-\zeta) and use the
``decoherence parameter'' \zeta as a measure for deviations from quantum
mechanics. We investigate several consequences of this modification of
semileptonic B^0 \bar B^0 decays. In particular, we show that when confronted
with the experimental values of the ratio R=(# like-sign dilepton events)/(#
opposite-sign dilepton events) and of the B_H--B_L mass difference, the ensuing
one standard deviation range of the decoherence parameter depends strongly on
the basis in the B^0--\bar B^0 space used to build the entangled B^0 \bar B^0
state. On the other hand, in quantum mechanics physical quantities are, of
course, independent of such arbitrary basis choices.


title:
Enhancement of Loop Induced $H^\pm W^\mp Z^0$ Vertex in Two
  Higgs-doublet Model

abstract:
  The non-decoupling effects of heavy Higgs bosons as well as fermions on the
loop-induced $H^\pm W^\mp Z^0$ vertex are discussed in the general two Higgs
doublet model. The decay width of the process $H^+ \to W^+ Z^0$ is calculated
at one-loop level and the possibility of its enhancement is explored both
analytically and numerically. We find that the novel enhancement of the decay
width can be realized by the Higgs non-decoupling effects with large
mass-splitting between the charged Higgs boson and the CP-odd one. This is due
to the large breakdown of the custodial $SU(2)_V$ invariance in the Higgs
sector. The branching ratio can amount to $10^{-2} \sim 10^{-1}$ for $m_{H^\pm}
= 300$ GeV within the constraint from the present experimental data. Hence this
mode may be detectable at LHC or future $e^+e^-$ linear colliders.