title:
Quantum Fluctuations and Particle Production of Coherently Oscillating
  Inflaton

abstract:
  We study a massive inflaton minimally coupled to the FRW Universe using the
semiclassical gravity derived from canonical quantum gravity. It is found that
the semiclassical quantum gravity leads to the power-law expansion $t^{2/3}$ in
an oscillatory phase of the inflaton. The particle production of the inflaton
in the expanding Universe restricts the duration of stable coherent
oscillations and parametric resonance. The semiclassical gravity shows a
significant difference that the Hubble constant does not oscillate in contrast
with the oscillatory behavior in classical gravity.


title:
Nucleus-nucleus collisions: what we have learned from the heavy ion
  program at CERN

abstract:
  In the first part, I give a brief description of the quark-gluon plasma
search at CERN and of some experimental results. In the second part, I review a
dynamical model of nucleus-nucleus interactions and propose a physical
interpretation of those results.


title: Introduction to XLOOPS

abstract:
  The program package XLOOPS calculates massive one- and two-loop Feynman
diagrams. It consists of five parts:
  i) a graphical user interface
  ii) routines for generating diagrams from particle input
  iii) procedures for calculating one-loop integrals both analytically and
numerically
  iv) routines for massive two-loop integrals
  v) programs for numerical integration of two-loop diagrams. The package
relies on the application of parallel space techniques. The treatment of tensor
structure and the separation of UV and IR divergences in analytic expressions
is described in this scheme. All analytic calculations are performed with
MAPLE. Two-loop examples taken from Standard Model calculations are presented.
The method has recently been extended to all two-loop vertex topologies,
including the crossed topology, graphs with divergent subloops and IR divergent
diagrams. This will be included in the XLOOPS package in the near future.


title: Photoproduction Off Nuclei, Part II: Particle and Jet Production

abstract:
  High energy multiparticle photoproduction off nuclear targets is studied. The
photon is assumed to interact in direct scattering processes or as a resolved
$q\bar{q}$-state according to the Generalized Vector Dominance Model. In the
description of resolved interactions multiple soft and hard processes in each
$q\bar{q}$--nucleon interaction are taken into consideration. The model,
formulated within the framework of the two-component Dual Parton Model, is
shown to agree with hadron production data from real and weakly virtual
photon-nucleus interactions. Differences between multiparticle production in
photon-nucleus and hadron-nucleus interactions and features of jet production
in photon-nucleus collisions at HERA-energies are discussed.


title: Vector Condensate Model of Electroweak Interactions

abstract:
  Motivated by the fact that the Higgs is not seen, we have proposed a version
of the standard model where the scalar doublet is replaced by a vector doublet
and its neutral member forms a nonvanishing condensate. Gauge fields are
coupled to the new vector fields B in a gauge invariant way leading to mass
terms for the gauge fields by condensation. B-particles become massive because
of their self interactions. Fermion and gauge field couplings are standard. Low
energy charged current phenomenology fixes the condensate. Fermion masses are
coming from the condensation and B-particle-fermion couplings. The
Kobayashi-Maskawa description is unchanged. The model has a low mementum scale
of about 2 TeV. For instance, from tree-graph unitarity at a scale of 1 TeV the
minimum mass of a charged B-particle is 369 GeV. Such B-particles are shown to
copiously produced at high-energy linear $e^+e^-$ colliders. The model survives
the test of oblique radiative corrections. To each momentum scale there exists
a range of B masses where the S, T parameters are compatible with the
experiment. For instance, at a scale of 1 TeV from the S parameter the minimum
mass of a charged (neutral) B is 200-350 GeV (400-550 GeV).


title: What have we learned from antiproton proton scattering?

abstract:
  From recent charge exchange measurements in the extreme forward direction, an
independent and precise determination of the pion nucleon coupling constant is
possible. This determination has reopened the debate on the value of this
fundamental coupling constant of nuclear physics. Precise measurements of
charge exchange observables at forward angles below 900 MeV/c would also give a
better understanding of the long range part of the two-pion exchange potential.
For example, the confirmation of the coherence of the tensor forces from the
pion exchange and the isovector two-pion exchange would be very valuable. With
the present data first attempts at an $\NbarN$ partial wave analysis have been
made where, as in nucleon nucleon scattering, the antinucleon nucleon high J
partial waves are mainly given by one-pion exchange. Finally a recent $\pbarp$
atomic cascade calculation and the fraction of P-state annihilation in gas
targets is commented on.


title: Theoretical uncertainties for weak decays: higher dimension operators

abstract:
  A brief review of recent results on computing contributions of higher
dimension operators to weak effective $\Delta S=1,2$ hamiltonians for light
quarks is presented.


title:
Can we distinguish Majorana and Dirac neutrinos in solar neutrino
  experiments ?

abstract:
  If neutrino conversions within the Sun result in partial polarization of
initial solar neutrino fluxes then a new opportunity to distinguish Majorana
and Dirac neutrinos by measuring the differential $\nu_ee$-scattering cross
section in solar neutrino detectors arises. The experiment like HELLAZ would be
preferable in testing of recoil electron spectra differences initiated by
Majorana and Dirac neutrinos since low energy recoil electrons ($T\geq 100
keV$) can be detected and electron energy and direction can be determined with
good precision.


title: Hybrid mesons: old prejudices and new spectroscopy

abstract:
  The models for hybrid mesons are discussed, in which the gluonic excitations
manifest themselves as the vibrations of the quark- antiquark QCD string. The
predictions for the spectra, decays and mixing with hadronic channels are
presented.


title: Virtual Photon Structure from Jet Production at HERA

abstract:
  The feasibility of measuring parton distribution functions of of virtual
photons via the jet production at HERA is investigated.


title: Discovering New Particles at Colliders

abstract:
  We summarize the activities of the New Particles Subgroup at the 1996
Snowmass Workshop. We present the expectations for discovery or exclusion of
leptoquarks at hadron and lepton colliders in the pair production and single
production modes. The indirect detection of a scalar lepton quark at polarized
$e^+e^-$ and $\mu^+\mu^-$ colliders is discussed. The discovery prospects for
particles with two units of lepton number is discussed. We summarize the
analysis of the single production of neutral heavy leptons at lepton colliders.


title: Compositeness and Supersymmetry Breaking in the Observable Sector

abstract:
  We consider models for physics beyond the standard model in which
supersymmetry is broken spontaneously near the weak scale by fields that are
charged under electroweak symmetry. We show that this is possible if some or
all of the light quarks and leptons are composite near the weak scale.
Flavor-changing neutral currents can be naturally suppressed by a GIM mechanism
or by approximate flavor symmetries. CP and B violation may be suppressed by
accidental symmetries. We give a general effective field theory analysis of
such models, and argue that they can be phenomenologically acceptable and lead
to interesting observable signals in future experiments. We then construct
explicit models based on non-perturbative effects discovered by Seiberg.


title: Next-to-leading nonperturbative calculation in heavy quarkonium

abstract:
  The next-to-leading nonperturbative contributions to heavy quarkonium systems
are calculated. The applicability of the Voloshin-Leutwyler approach to heavy
quarkonia systems for the physical cases of Bottomonium and Charmonium is
investigated. We study whether the background gluon field correlation time can
be considered to be infinity or not, by calculating the leading correction to
this assumption and checking whether the expansion is under control. A
phenomenological analysis of our results is also performed. The results make us
feel optimistic about the $\Upsilon(1S)$ and to a lesser extent about the
$J/\psi$ but do not about higher levels. We also briefly discuss the connection
with different models where a finite gluon correlation time is introduced.


title:
Proton Decay and the Dimopoulos-Wilczek Mechanism in Minimal SO(10)
  Models

abstract:
  Proton decay is examined within the framework of certain SO(10) models which
have low dimension representations compatible with the recently found
constraints coming from string theory, and which use the Dimopoulos-Wilczek
mechanism to solve the doublet-triplet splitting problem. It is found that the
mass parameter that controls proton decay rate is intimately related to the low
energy data via the coupling unification condition, and that a suppression of
proton decay is achieved at the cost of large threshold effects. Furthermore,
in cases where there are states with intermediate masses, the threshold effects
further enhance proton decay. The experimental bound then severely constrains
the parameter space of these models. Some possible solutions are suggested.


title:
Chiral Symmetry Breaking in Axial Gauge QCD from the Dyson Schwinger
  Equations

abstract:
  We investigate the nonperturbative behaviour of the quark propagator in axial
gauge using a truncation of the Dyson-Schwinger equations which respects the
Ward-Takahashi identity and multiplicative renormalisability. We demonstrate
that above a critical coupling $\alpha_c$, which depends on the form of the
gluon propagator, one can obtain massive solutions for both explicit and
dynamically generated quark masses. The stability of these is discussed in the
context of the Cornwall-Jackiw-Tomboulis effective action.


title:
Isolated Photons at Hadron Colliders at O($\alpha alpha_s^2$) (I): Spin
  Averaged Case

abstract:
  The cross sections for isolated and non-isolated prompt photon production
with unpolarized hadron beams are studied at order $\alpha\alpha_s^2$. Two
methods of performing the calculations are compared. One uses purely analytic
techniques and the second uses a combination of analytic and Monte Carlo
techniques to perform the phase-space integrations. The results of the analytic
and Monte Carlo methods are compared both before and after isolation cuts are
placed on the photon. Fragmentation contributions are included at
next-to-leading order in the analytic case, and the question of the infrared
sensitivity of this contribution once isolation is implemented is addressed.
Numerical results are presented and compared with the latest CDF data for
$p\bar{p} \to \gamma+X$ using the latest parton densities for the proton.


title: Chiral Symmetry in algebraic and analytic approaches

abstract:
  We compare among themselves two different methods for the derivation of
results following from the requirement of polynomial boundedness of tree-level
chiral amplitudes. It is shown that the results of the algebraic approach are
valid also in the framework of the analytical one. This means that the system
of Sum Rules and Bootstrap equations previously obtained with the help of the
latter approach can be analyzed in terms of reducible representations of the
unbroken Chiral group with the known structure of the mass matrix.


title: B_q -> l^+ l^- gamma decays in light cone QCD

abstract:
  The radiative dileptonic decays B_s(B_d) -> l^+ l^- gamma (l = e, mu) are
investigated within the Standard Model . The transition formfactors are
calculated in the framework of the light cone QCD sum rules method and it is
found that the branching ratios are B(B_s -> e^+ e^- gamma) =2.35 x 10^(-9),
B(B_s -> mu^+ mu^- gamma) =1.9 x 10^(-9), B(B_d -> e^+ e^- gamma) = 1.5 x
10^(-10) and B(B_d -> \mu^+ \mu^- gamma) = 1.2 x 10^(-10). A comparison of our
results with the constituent quark model predictions on the branching ratios is
presented.


title: The Constrained MSSM Revisited

abstract:
  Within the Constrained Minimal Supersymmetric Model (CMSSM) it is possible to
predict the low energy gauge couplings and masses of the 3 generation particles
from a few supergravity inspired parameters at the GUT scale. Moreover, the
CMSSM predicts electroweak symmetry breaking due to large radiative corrections
from the Yukawa couplings, thus relating the $Z^0$ boson mass to the top quark
mass via the renormalization group equations (RGE). In addition, the
cosmological constraints on the lifetime of the universe are considered in the
fits. The new precise measurements of the strong coupling constant and the top
mass as well as higher order calculations of the $b \to s\gamma$ rate exclude
perfect fits in the CMSSM, although the discrepancies from the best fit
parameters are below the $2\sigma$ level.


title: Global Fits of the SM and MSSM to Electroweak Precision Data

abstract:
  A program including all radiative corrections to the MSSM at the same level
as the radiative corrections to the SM has been developed and used to perform
global fits to all electroweak data from LEP, SLC and the Tevatron and the
radiative b->sgamma decay from CLEO. Values of the strong coupling constant at
the M_Z scale and $\sin^2\theta_{\overline{MS}}$ are derived, both in the SM
and MSSM. Recent updates on ectroweak data, which have been presented at the
Warsaw Conference in summer 1996, reduce the R_b anomaly from a 3.2 \sigma to a
1.8 \sigma effect. In addition, the $b\rightarrow s\gamma$ decay is 30% below
the SM prediction. In the MSSM light stops and light charginos increase R_b and
decrease the $b\rightarrow s\gamma$ rate, so both observations can be brought
into agreement with the MSSM for the same region of parameter space. However,
the resulting $\chi^2$ value for the MSSM fits is only marginally lower and in
addition, the splitting in the stop sector has to be unnaturally high.


title: Conformal blocks in the QCD Pomeron formalism

abstract:
  The conformal invariance properties of the QCD Pomeron in the transverse
plane allow us to give an explicit analytical expression for the conformal
eigenvectors in the mixed representation in terms of two conformal blocks, each
block being the product of an holomorphic times an antiholomorphic function.
This property is used to give an exact expression for various functions of
interest, the Pomeron amplitude in both momentum and impact-parameter
variables, the QCD dipole multiplicities and dipole-dipole cross-sections in
the whole parameter space, and we recover the expression of the four-point
gluon Green function given recently by Lipatov


title:
Higgs Production at the LHC: an Update on Cross Sections and Branching
  Ratios

abstract:
  New theoretical and experimental information motivates a re-examination of
the Standard Model Higgs production rates at the LHC pp collider. We present
calculations of the relevant cross sections and branching ratios, including
recently calculated QCD next-to-leading order corrections, new parton
distributions fitted to recent HERA structure function data, and new values for
electroweak input parameters, in particular for the top quark mass. Cross
sections are calculated at two collider energies, $\sqrt{s} = 10$ TeV and 14
TeV.


title: The U.V. Price for Symmetry Non-Restoration

abstract:
  We study the non restoration of symmetries with a local order parameter in
field theory at finite temperature. After giving an interpretation of the
phenomenon, we show that hierarchy problems are a necessary condition for its
realization in renormalizable theories. We then use a large N treatment, and
find that high temperature symmetry can stay broken in this limit (in
opposition with a previous result), and further that the running of couplings
reinforces the effect in the simplest model with two scalars.


title:
Recoil Corrections of Order $(Z\alpha)^6(m/M)m$ to the Hydrogen Energy
  Levels Revisited

abstract:
  The recoil correction of order $(Z\alpha)^6(m/M)m$ to the hydrogen energy
levels is recalculated and a discrepancy existing in the literature on this
correction for the 1S energy level, is resolved. An analytic expression for the
correction to the S-levels with arbitrary principal quantum number is obtained.


title:
Non-equilibrium QCD: Interplay of hard and soft dynamics in high-energy
  multi-gluon beams

abstract:
  A quantum-kinetic formulation of the dynamical evolution of a high-energy
non-equilibrium gluon system at finite density is developed, to study the
interplay between quantum fluctuations of high-momentum (hard) gluons and the
low-momentum (soft) mean color-field that is induced by the collective motion
of the hard particles. From the exact field-equations of motion of QCD, a
self-consistent set of approximate quantum-kinetic equations are derived by
separating hard and soft dynamics and choosing a convenient axial-type gauge.
This set of master equations describes the momentum space evolution of the
individual hard quanta, the space-time development of the ensemble of hard
gluons, and the generation of the soft mean-field by the current of the hard
particles. The quantum-kinetic equations are approximately solved to order g^2
(1+gA) for a specific example, namely the scenario of a high-energy gluon beam
along the lightcone, demonstrating the practical applicability of the approach.


title:
Direct photon production in polarized hadron collisions at collider and
  fixed target energies

abstract:
  Recently determined next-to-leading order sets of polarized parton
distributions are used to study large-p_T $\vec{p}\vec{p}\rightarrow \gamma+X$
at $\sqrt{s}=38, 100 and 500 GeV$. Certain conversion terms, necessary to use
the above sets, are determined. It is concluded that, to distinguish between
the above sets, planned RHIC experiments should be successful, in particular at
c.m. photon pseudorapidity $\simeq 1$, and that a proposed HERA-$\vec{N}$ fixed
target experiment should have rather large accuracy at relatively large $x_T
(=2p_T/\sqrt{s})$.


title: A Little Large N Group Theory

abstract:
  We discuss the group theory relevant to the ground-state baryons in large N_c
QCD. For very large representation, the group generators become classical
variables. We find the form of the classical generators for the completely
symmetric N index representation of $SU(m)$ as $N\rightarrow\infty$ and derive
an integral formula for the matrix elements of an arbitrary polynomial in the
group generators between low-spin baryon states in the large N limit.


title: Issues of Spin Physics at RHIC

abstract:
  Some novel aspects of spin studies at RHIC are summarized along with the
persistent problems. Among them are those which emphasize the role of angular
orbital momentum in the spin structure of the constituent quarks.


title: Baryons in chiral constituent quark model

abstract:
  Beyond the spontaneous chiral symmetry breaking scale light and strange
baryons should be considered as systems of three constituent quarks with an
effective confining interaction and a flavor-spin chiral interaction that is
mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the
constituent quarks. One cannot exclude, however, the possibility that this
flavor-spin interaction has an appreciable vector- and higher meson exchange
component.


title: Texture of fermion mass matrices in partially unified theories

abstract:
  We investigate the texture of fermion mass matrices in theories with partial
unification (for example $ SU(2)_L\times SU(2)_R\times SU(4)_c$) at a scale
$\sim 10^{12}$ GeV. Starting with the low energy values of the masses and the
mixing angles, we find only two viable textures with atmost four texture zeros.
One of these corresponds to a somewhat modified Fritzsch textures. A
theoretical derivataion of these textures leads to new interesting relations
among the masses and the mixing angles.


title:
1/m_b^2 correction to the left-right lepton polarization asymmetry in
  the decay B -> X_s mu^+ mu^-

abstract:
  Using a known result by Falk et al. for the 1/m_b^2 correction to the
dilepton invariant mass spectrum in the decay B \rightarrow X_s \mu^+ \mu^-, we
calculate the 1/m_b^2 correction to the left-right muon polarization asymmetry
in this decay. Employing an up-to-date range of values for the non-perturbative
parameter \lambda_1, we find that the correction is much smaller than it should
have been expected from the previous work by Falk et al.


title: Derivative Corrections To The Sphaleron Energy

abstract:
  We investigate the effects of inhomogeneous scalar field configurations on
effective action at finite temperature. Recently, Walliser et al. have
calculated the leading perturbative corrections to the wave function correction
term $Z(\phi,T)$, for the standard model at finite temperature. Here we follow
their results and apply them to calculate the effective energy of the sphaleron
solution, including derivative correction term $Z(\phi,T)$. The dominant
contribution to $Z(\phi,T)$ comes from vector boson loops. We also study the
possible effects of corrected sphaleron energy on the baryon number violation
rate in the standard model.


title: Clan concept in multiparticle dynamics and the NB ``enigma''

abstract:
  A summary of main results on NB (Negative Binomial) regularity and related
clan concept since their first appearance in multiparticle dynamics is
presented.


title: An Introduction to Supersymmetry

abstract:
  A fairly elementary introduction to supersymmetric field theories in general
and the minimal supersymmetric Standard Model (MSSM) in particular is given.
Topics covered include the cancellation of quadratic divergencies, the
construction of the supersymmetric Lagrangian using superfields, the field
content of the MSSM, electroweak symmetry breaking in the MSSM, mixing between
different superparticles (current eigenstates) to produce mass eigenstates, and
the embedding of the MSSM in so--called minimal supergravity.


title: Analysis of Substructures in Charm Decays

abstract:
  Recent results on Dalitz analysis of three-pseudoscalar decays are discussed
in the context of probing charm hadronic-decay mechanisms: the role of FSI
effects, which create phase shifts between the interfering resonant channels,
can be studied in the different decay modes and the annihilation contribution
measured in the charm sector through the $D^+_s \to \pi^+\pi^-\pi^+$ decay.


title: Review of Heavy Quark Effective Theory

abstract:
  A short review of a few selected topics in Heavy Quark Effective Theory is
given. Applications to exclusive decays are discussed.


title:
Dynamical mass generation in 2+1-dimensional electrodynamics in an
  external magnetic field

abstract:
  The influence of a magnetic field on the mass generation in 2+1 dimensional
QED is considered.It is shown that the magnetic field is a catalyst of the
generation of a fermion dynamical mass. The mass arises in the system with
arbitrary number of fermions, not only with $N\leq 4$, as it is in the system
without the magnetic field. The polarization tensor is calculated for a
constant magnetic field.


title:
What can the final state particles in diffractive lepton-nucleon
  scattering tell us?

abstract:
  The colorless objects(s) in diffractive lepton-nucleon scattering in the
small-$x_B$ region can be probed by examing the final state particles in such
processes: (A) Perform multiplicity and/or energy factorial moment analyses,
and check especially the $x_B$- and $Q^2$-dependence of the
intermittency-indices. (B) Examine the diffractive structure function
$F_2^{D(3)}(\beta,Q^2;x_P)$ as function of $x_P$ for different $\beta$ and
$Q^2$. It is shown that such analyses and measurements can yield useful
information on the hadronization process and on the intrinsic properties of the
colorless objects. In particular, the observation of power-law distributions of
$F_2^{D(3)}(\beta,Q^2;x_P)$ with respect to $x_P$ and with respect to $x_B$ ---
independent of $\beta$ and $Q^2$-values may be considered as strong indication
for the existence of self-organized criticality in gluon-cluster formation
processes.


title: Sum rules for asymptotic form factors in $e^+ e^- -> W^+ W^-$ scattering

abstract:
  At very large energies and in $SU(2)_L\otimes U(1)_Y$ gauge theories, the
trilinear gauge boson vertices relevant for $e^+e^- \to W^+W^-$ scattering are
related in a simple way to the gauge boson self-energies. We derive these
relations, both from the requirement of perturbative unitarity and from the
Ward Identities of the theory. Our discussion shows that, in general, it is
never possible to neglect vector boson self-energies when computing the form
factors which parametrize the $e^+ e^- \to W^+ W^-$ helicity amplitudes. The
exclusion of the self-energy contributions would lead to estimates of the
effects wrong by orders of magnitudes. We propose a simple way of including the
self-energy contributions in an appropriate definition of the form factors.


title:
Damping rates of hard momentum particles in a cold ultrarelativistic
  plasma

abstract:
  We compute the damping rates of one-particle excitations in a cold
ultrarelativistic plasma to leading order in the coupling constant e for three
types of interaction: Yukawa coupling to a massless scalar boson, QED and QCD.
Damping rates of charged particles in QED and QCD are of order e^3 mu, while
damping rates of other particles are of order e^4 mu or e^4 mu log(1/e). We
find that the damping rate of an electron or of a quark is constant far from
the Fermi surface, and decreases linearly with the excitation energy close to
the Fermi surface. This unusual behavior is attributed to the long-range
magnetic interactions.


title: Fermions and Condensates on the Light-Front

abstract:
  Light-Front quantization is one of the most promising and physical tools
towards studying deep inelastic scattering on the basis of quark gluon degrees
of freedom. The simplified vacuum structure (nontrivial vacuum effects can only
appear in zero-mode degrees of freedom) and the physical basis allows for a
description of hadrons that stays close to intuition. I am reviewing recent
progress in understanding the deep connection between renormalization of
light-front Hamiltonians, effective light-front Hamiltonians and nontrivial
vacuum condensates.


title:
Compatibility of a model for the QCD-Pomeron and chiral-symmetry
  breaking phenomenologies

abstract:
  The phenomenology of a QCD-Pomeron model based on the exchange of a pair of
non-perturbative gluons, i.e. gluon fields with a finite correlation length in
the vacuum, is studied in comparison with the phenomenology of QCD chiral
symmetry breaking, based on non-perturbative solutions of Schwinger-Dyson
equations for the quark propagator including these non-perturbative gluon
effects. We show that these models are incompatible, and point out some
possibles origins of this problem.


title: Asymptotic Limits and Structure of the Pion Form Factor

abstract:
  We use dispersive techniques to address the behavior of the pion form factor
as $Q^2 \to \infty$ and $Q^2 \to 0$. We perform the matching with the
constraints of perturbative QCD and chiral perturbation theory in the high
energy and low energy limits, leading to four sum rules. We present a version
of the dispersive input which is consistent with the data and with all
theoretical constraints. The results indicate that the asymptotic perturbative
QCD limit is approached relatively slowly, and give a model independent
determination of low energy chiral parameters.


title: Non-perturbative Methods in Kaon Physics: Aside from the Lattice

abstract:
  I discuss the progress in the use of analytic techniques for low energy QCD,
in particular as applied to kaon physics. These methods are becoming
increasingly powerful and we have gained a good deal of control over the
difficult hadronic interactions. There are continuing developments, and I
speculate on the ways that these techniques may become yet more sophisticated
in the future.


title:
Endpoint Structure in Beta Decay from Coherent Weak-Interaction of the
  Neutrino

abstract:
  Recent tritium beta decay experiments yield unphysical negative best-fit
values for the square of the neutrino mass. An unidentified bump-like excess of
counts few eV below the endpoint in the electron energy spectrum has been
tentatively recognized as the source of this anomaly. It is shown that the
repulsive potential acting on the emitted antineutrino and originating in its
coherent weak-interaction with the daughter atom may effectively account for
this excess.


title: QCD: Questions, Challenges, and Dilemmas

abstract:
  An introduction to some outstanding issues in QCD is presented, with emphasis
on work by Diakonov and co-workers on the influence of the instanton vacuum on
low-energy QCD observables. This includes the calculation of input
valence-parton distributions for deep-inelastic scattering.


title:
FCNC in left-right symmetric theories and constraints on the
  right-handed scale

abstract:
  We revise the limits on the FCNC higgses in manifestly left-right symmetric
theories. It is shown that the combination of the Kobayashi-Maskawa
CP-violation with the tree level $\Delta S=2$ higgs exchange gives very large
contribution to the CP-violating $\epsilon$ parameter. It leads to the new
strong constraint on the FCNC higgs mass, M>50- 100 TeV, enhanced by factor of
the order $\sqrt{m_t/m_c}$. Being addressed to the supersymmetric left-right
models, FCNC problem requires both right-handed scale and supersymmetric mass
parameters be heavier than 50 TeV for $tan\beta\sim 1$. The most relaxed case
corresponds to $tan\beta\sim 20- 30$ where right-handed scale can be of the
order of few TeV.


title: Three Neutrino Flavors are Enough

abstract:
  It is shown that it is possible to account for all three experimental
indications for neutrino oscillations with just three neutrino flavors. In
particular, we suggest that the solar and atmospheric neutrino anomalies are to
be explained by the same mass difference and mixing. Possible implications and
future tests of the resulting mass-mixing pattern are given.


title: Nucleon form factors: From the space-like to the time-like region

abstract:
  I discuss how dispersion relations can be used to analyse the nucleon
electromagnetic form factors, with particular emphasis on the constraints from
unitarity and pQCD. Results for nucleon radii, vector-meson couplings, the
onset of pQCD and bounds on the strangeness form factors are presented. The em
form factors in the time-like region reveal some interesting physics which is
not yet understood in full detail. The need for a better data basis at low,
intermediate and large momentum transfer and also in the time-like region is
stressed.


title: Baryogenesis from mixed particle decays

abstract:
  We consider the $CP$ violating asymmetries produced in the decay of heavy
particles, studying the effects of heavy particle mixing for arbitrary mass
splittings. A considerable enhancement of the asymmetries is achieved when the
masses of the mixed states are comparable, and the enhancement is maximal for
mass splittings of the order of the widths of the decaying particles. We apply
the results to the particular case of heavy scalar neutrino decays relevant for
leptogenesis scenarios.


title: QED and Electroweak Corrections to Deep Inelastic Scattering

abstract:
  We describe the state of the art in the field of radiative corrections for
deep inelastic scattering. Different methods of calculation of radiative
corrections are reviewed. Some new results for QED radiative corrections for
polarized deep inelastic scattering at HERA are presented. A comparison of
results obtained by the codes POLRAD and HECTOR is given for the kinematic
regime of the HERMES experiment. Recent results on radiative corrections to
deep inelastic scattering with tagged photons are briefly discussed.


title: Charmed decays of the B-meson in the quark model

abstract:
  Exclusive and inclusive, semileptonic and non-leptonic, charmed decays of the
B-meson are investigated in the context of a phenomenological quark model.
Bound-state effects are taken care of by adopting a single (model-dependent)
non-perturbative wave function, describing the motion of the light spectator
quark in the B-meson. A nice reproduction of both exclusive and inclusive
semileptonic data is obtained. Our predictions for the electron spectrum are
presented and compared with those of the Isgur-Scora-Grinstein-Wise quark
model. Finally, our approach is applied to the calculation of inclusive
non-leptonic widths, obtaining a remarkable agreement with experimental
findings.


title: Diquark model of exotic mesons

abstract:
  This is a conference mostly devoted to diquarks. Although an exotic meson can
in principle be composed of a diquark and an antidiquark, such an exotic is
unlikely to be experimentally observable in the near future. The reason,
according to the model, is that diquark-antidiquark exotics have masses well
above the threshold for decay into two mesons, and are likely to have widths
too large to make them observable. A possible exception is a $ u d \bar b \bar
b$ exotic, but it will be a long time before such a state can be observed even
if it is stable against strong decay.


title: Diquark model of dibaryons

abstract:
  A diquark model previously formulated to describe exotic mesons is extended
to dibaryons. In the model, dibaryons containing only light quarks are unbound.
The $H$ dibaryon, consisting of $uuddss$ quarks, is unstable by about 90 MeV or
more, and should decay strongly into two $\Lambda$ baryons. A charmed dibaryon
$H_c$, composed of $uuddsc$, is unstable by about 60 MeV or more and should
decay strongly into $\Lambda + \Lambda_c$. On the other hand, we find that a
bottom dibaryon $H_b$, made of $uuddsb$, may be just bound by about 10 MeV with
respect to $\Lambda + \Lambda_b$. If so, it should decay weakly into various
final states with a charmed hadron. A possible two-body decay would be into
$\Lambda + \Lambda_c$.


title: CP violating couplings in Z -> 3 jet decays revisited

abstract:
  Possible CP violating effects in $Z\rightarrow$ 3 jet decays are
investigated. The analysis assumes the presence of CP violating $Zq\bar qG$
couplings. The contribution of these couplings to the $Z\rightarrow q\bar qG$
decay width is calculated for different cut algorithms, including nonzero quark
masses. Various CP--odd observables are discussed and it is shown that their
sensitivity can change significantly if one uses normalized or unnormalized
momentum vectors for their construction. Optimal observables are proposed which
allow to measure the new couplings simultaneously.


title: Electromagnetic properties of neutral and charged spin 1 particles

abstract:
  The structure of the electromagnetic vertex of spin-1 particles are studied
in a general way, for the diagonal as well as the off-diagonal couplings. In
each case, we consider in detail the consequences of gauge invariance and the
space-time discrete symmetries, paying particular attention to the implications
for the couplings of the photon to neutral gauge bosons, which arise in higher
orders. Several general results concerning the static electromagnetic
properties of neutral bosons are derived, analogous to the results that are
well known in the case of neutral spin-1/2 particles.


title:
W+4jet irreducible background events from QCD in top and Higgs searches
  at the Next Linear Collider

abstract:
  Irreducible background effects due to $e^+e^-\to W^\pm + bbjj$ and $e^+e^-\to
W^\pm + jjjj$ events produced via QCD in top-antitop production and heavy Higgs
searches in the bremsstrahlung channel are studied at the Next Linear Collider.
Various distributions relevant to phenomenological analyses are given and
compared to those expected from top and Higgs signals in the decay channel
$b\bar bW^+W^-\to b\bar b W^\pm jj$. This analysis follows similar ones
previously carried out for the case of the irreducible background proceeding
via electroweak interactions


title: Factorization for hard exclusive electroproduction of mesons in QCD

abstract:
  We formulate and prove a QCD factorization theorem for hard exclusive
electroproduction of mesons in QCD. The proof is valid for the leading power in
Q and all logarithms. This generalizes previous work on vector meson production
in the diffractive region of small x. The amplitude is expressed in terms of
off-diagonal generalizations of the usual parton densities. The full theorem
applies to all kinds of meson and not just to vector mesons. The parton
densities used include not only the ordinary parton density, but also the
helicity density (g_1 or $\Delta q$) and the transversity density ($h_1$ or
$\delta q$), and these can be probed by measuring the polarization of the
produced mesons with unpolarized protons.


title: Behaviour of the Absorptive Part of the W Electromagnetic Vertex

abstract:
  The absorptive part of the $WW\gamma$ vertex induced by massive fermion loops
is considered for different kinematical configurations. We show that the axial
part of this vertex is different from zero not only when massive fermions are
involved but also for massless fermion loops, if one of the W bosons is
space-like and the other is time-like. We also discuss in what sense Low's soft
photon theorem is satisfied.


title: Solar neutrino spectroscopy (before and after SuperKamiokande)

abstract:
  Results of solar neutrino spectroscopy based on data from four experiments
are presented. Perspectives related to forthcoming experiments are discussed.
Implications of the results for neutrino properties are considered.


title: Physics Opportunities at ELFE

abstract:
  I review some central physics opportunities at the 15 ... 30 GeV continuous
beam electron accelerator ELFE, proposed to be built in conjunction with the
DESY linear collider. Our present detailed knowledge of single parton
distributions in hadrons and nuclei needs to be supplemented by measurements of
compact valence quark configurations, accessible through hard exclusive
scattering, and of compact multiparton subsystems which contribute to
semi-inclusive processes. Cumulative (x>1, x_F>1) processes in nuclei measure
short-range correlations between partons belonging to different nucleons in the
same nucleus. The same configurations may give rise to subthreshold production
of light hadrons and charm.


title:
Single-photon signals at LEP in supersymmetric models with a light
  gravitino

abstract:
  We study the single-photon signals expected at LEP in models with a very
light gravitino. The dominant process is neutralino-gravitino production (e+e-
-> chi+ G) with subsequent neutralino decay via chi->gamma+G, giving a
gamma+E_miss signal. We first calculate the cross section at arbitrary
center-of-mass energies and provide new analytic expressions for the
differential cross section valid for general neutralino compositions. We then
consider the constraints on the gravitino mass from LEP 1 and LEP161
single-photon searches, and possible such searches at the Tevatron. We show
that it is possible to evade the stringent LEP 1 limits and still obtain an
observable rate at LEP 2, in particular in the region of parameter space that
may explain the CDF e+e+gamma+gamma+E_T,miss event. As diphoton events from
neutralino pair-production would not be kinematically accessible in this
scenario, the observation of whichever photonic signal will discriminate among
the various light-gravitino scenarios in the literature. We also perform a
Monte Carlo simulation of the expected energy and angular distributions of the
emitted photon, and of the missing invariant mass expected in the events.
Finally we specialize the results to the case of a recently proposed
one-parameter no-scale supergravity model.


title:
Analytic perturbation theory in QCD and Schwinger's connection between
  the beta-function and the spectral density

abstract:
  We argue that a technique called analytic perturbation theory leads to a
well-defined method for analytically continuing the running coupling constant
from the spacelike to the timelike region, which allows us to give a
self-consistent definition of the running coupling constant for timelike
momentum. The corresponding $\beta$-function is proportional to the spectral
density, which confirms a hypothesis due to Schwinger.


title: Cosmic Strings in Theories With Dynamical Symmetry Breaking

abstract:
  We study the classical cosmic string solution in a theory with dynamical
$U(1)$ symmetry breaking. We calculate the energy per unit length of the string
and compare it to that obtained in a model with a fundamental Higgs. We find
that the predictions of the standard Abelian Higgs model are quite stable
towards the addition of higher dimension operators expected in the effective
Lagrangian for the order parameter in a model with dynamical symmetry breaking,
at least for small coupling constant $\lambda$.


title: Baryogenesis from baryon number violating scalar interactions

abstract:
  In the following work we consider the possibility of explaining the observed
baryon number asymmetry in the universe from simple baryon number violating
modifications, involving massive scalar bosons, to the Standard Model. In these
cases baryon number violation is mediated through a combination of Yukawa and
scalar self-coupling interactions. Starting with a previously compiled
catalogue of baryon-number violating extensions of the Standard Model, we
identify the minimal subsets which can induce a $B-L$ asymmetry and thus be
immune to sphaleron washout. For each of these models, we identify the region
of parameter space that leads to the production of a baryon number asymmetry of
the correct order of magnitude.


title:
Critical coupling for dynamical chiral-symmetry breaking with an
  infrared finite gluon propagator

abstract:
  We compute the critical coupling constant for the dynamical chiral-symmetry
breaking in a model of quantum chromodynamics, solving numerically the quark
self-energy using infrared finite gluon propagators found as solutions of the
Schwinger-Dyson equation for the gluon, and one gluon propagator determined in
numerical lattice simulations. The gluon mass scale screens the force
responsible for the chiral breaking, and the transition occurs only for a
larger critical coupling constant than the one obtained with the perturbative
propagator. The critical coupling shows a great sensibility to the gluon mass
scale variation, as well as to the functional form of the gluon propagator.


title:
Model independent analysis of the simultaneous mixing of gauge bosons
  and mixing of fermions

abstract:
  We discuss the case of simultaneous mixing of gauge bosons and mixing of
fermions in a model independent way and for a variety of extra-fermion
representations.
  In this context we analyze a class of lepton family violating processes,
namely Z --> e tau, Z --> mu tau, Z --> e mu, mu --> e e e, tau --> e e e, tau
--> mu mu mu, tau --> e mu mu and tau --> mu e e in the presence of one extra
neutral gauge boson, Z', with universal, non-universal or family changing
couplings.
  We derive bounds on the combined effect of Z-Z' mixing and ordinary--exotic
lepton mixing.


title:
Constraints from $b \to s \gamma$ on gauge-mediated supersymmetry
  breaking models

abstract:
  We consider the branching ratio of $b \to s\gamma$ in gauge mediated
supersymmetry breaking theories. Useful bounds on the parameter space of these
models are derived from the experimental bounds on $b \to s\gamma$. Constraints
on masses of NLSP are presented as a function of $tan\beta$ and $M/\Lambda$ for
$\mu<0$ and $\mu>0$.


title: Pomerons and Jet Events at HERA

abstract:
  We study two and three jet events with a large rapidity gap at HERA. Unlike
in the Ingelman-Schlein approach we do not adscribe a structure to the Pomeron.
Instead, the coupling of the Pomeron to quarks or gluons is taken pointlike,
which makes the model easy to test: the only degrees of freedom are the
coupling constants of the Pomeron to the quarks or the gluons and a cutoff
procedure to keep the Pomeron-gluon coupling well behaved.


title:
Calculation of two-loop top-quark and Higgs-boson corrections in the
  electroweak Standard Model

abstract:
  A combination of algebraical and numerical techniques for calculating
two-loop top-quark and Higgs-boson corrections to electroweak precision
observables like $\Delta r$ or the $\rho$-parameter is presented. The
renormalization is performed within the on-shell scheme. The results of the
calculations are valid for arbitrary values of $m_t$, $M_H$ and of the
gauge-boson masses. An example is treated where the full result is compared to
the result obtained via an expansion up to next-to-leading order in $m_t$. As
an application, results for the Higgs-mass dependent top-contributions to
$\Delta r$ are given.


title:
Orbiting valence quarks and their influence on the structure functions
  of the nucleon

abstract:
  It is shown that intrinsic orbital motion of the valence quarks has large
influences on the spin-dependent as well as the spin-averaged nucleon structure
functions. Its connection with the observed ``very small contribution of quark
spin to nucleon spin'' and the observed violation of Gottfried sum rule is
discussed.


title:
Testing the mechanisms proposed in different models for single-spin
  asymmetries

abstract:
  It is shown that the origin of the striking left-right asymmetries observed
in single-spin inclusive hadron production processes in high energy
hadron-hadron collisions can be traced by performing suitable experiments.
Several new experiments are proposed. The possible outcomes are summarized
together with those of other relevant experiments which have already been
suggested. It is pointed out that the results of such a set of experiments will
not only be able to differentiate between existing theoretical models, but also
be helpful in locating the source(s) of the observed asymmetries.


title: Standard Model and Electroweak Interaction: Phenomenology

abstract:
  The status of the LEP 1 results, the LEP 2 perspectives and some recent
developments in the high energy behavior of electron-positron annihilation are
briefly discussed.


title:
Explicit solutions of the multi-loop integral recurrence relations and
  its application

abstract:
  The approach to the constructing explicit solutions of the recurrence
relations for multi-loop integrals are suggested. The resulting formulas
demonstrate a high efficiency, at least for 3-loop vacuum integrals case. They
also produce a new type of recurrence relations over the space-time dimension.


title:
Inclusive Two-Jet Production at HERA: Direct and Resolved Cross Sections
  in Next-to-Leading Order QCD

abstract:
  We have calculated inclusive two-jet cross sections in next-to-leading order
QCD for low Q^2 ep collisions superimposing direct and resolved contributions.
Infrared and collinear singularities in the virtual and real contributions are
cancelled with the phase space slicing method. Various inclusive two-jet
distributions have been computed. The results are compared with recent data
from the ZEUS collaboration at HERA.


title: Electroweak interactions -- theory

abstract:
  In the first part of this talk there is given a very brief review of the
status of the Standard Model (SM). In the second part I discuss electroweak
interactions and physics beyond the SM.


title: The evolution of the nonsinglet twist-3 parton distribution function

abstract:
  The twist three contributions to the $Q^2$-evolution of the spin-dependent
structure function $g_2(x_{Bj},Q^2)$ are considered in the non-local operator
product approach. Defining appropriate twist three distribution function we
derive their evolution equation for the nonsinglet case in leading order
approximation. In the limit $x_{Bj} \rightarrow 1$ as well as in the large
$N_c$ limit we confirm the result that the evolution of the nonsinglet part of
$g_2$ is governed by a Gribov-Lipatov-Altarelli-Parisi equation.


title:
Why Pad\'e Approximants reduce the Renormalization-Scale dependence in
  QFT?

abstract:
  We prove that in the limit where the beta function is dominated by the 1-loop
contribution (``large beta_0 limit'') diagonal Pad\'e Approximants (PA's) of
perturbative series become exactly renormalization scale (RS) independent. This
symmetry suggest that diagonal PA's are resumming correctly contributions from
higher order diagrams that are responsible for the renormalization of the
coupling-constant. Non-diagonal PA's are not exactly invariant, but generally
reduce the RS dependence as compared to partial-sums. In physical cases,
higher-order corrections in the beta function break the symmetry softly,
introducing a small scale and scheme dependence. We also compare the Pad\'e
resummation with the BLM method. We find that in the large-N_f limit using the
BLM scale is identical to resumming the series by a $x[0/n]$ non-diagonal PA.


title: Anomalous Gauge Boson Couplings

abstract:
  The measurement of anomalous gauge boson self couplings is reviewed for a
variety of present and planned accelerators. Sensitivities are compared for
these accelerators using models based on the effective Lagrangian approach. The
sensitivities described here are for measurement of generic parameters kappa_v,
lambda_v, etc., defined in the text. Pre-LHC measurements will not probe these
couplings to precision better than O(1/10). The LHC should be sensitive to
better than O(1/100), while a future NLC should achieve sensitivity of
O(1/1000) to O(1/10000) for center of mass energies ranging from 0.5 to 1.5
TeV.


title:
Supersymmetric Electroweak Corrections to Single Top Quark Production at
  the Fermilab Tevatron

abstract:
  We have calculated the $O(\alpha_{ew} M_t^2/M_W^2)$ supersymmetric
electroweak corrections to single top quark production via $q\bar q' \to t\bar
b$ at the Fermilab Tevatron in the minimal supersymmetric model. The
supersymmetric electroweak corrections to the cross section are a few percent
for $tan \beta> 1$, and can exceed 10% for $tan\beta<1$. The combined effects
of SUSY electroweak corrections and the Yukawa corrections can exceed 10% for
favorable parameter values, which might be observable at a high-luminosity
Tevatron.


title: Diffractive Dissociation In The Interacting Gluon Model

abstract:
  We have extended the Interacting Gluon Model (IGM) to calculate diffractive
mass spectra generated in hadronic collisions. We show that it is possible to
treat both diffractive and non-diffractive events on the same footing, in terms
of gluon-gluon collisions. A systematic analysis of available data is
performed. The energy dependence of diffractive mass spectra is addressed. They
show a moderate narrowing at increasing energies. Predictions for LHC energies
are presented.


title: Searches for SUSY Particles at HERA

abstract:
  Searches at the e-p collider HERA for supersymmetric partners of the Standard
Model fermions are presented. Assuming R-parity conservation, selectrons and
squarks of the Minimal Supersymmetric Standard Model are excluded for masses up
to 65 GeV in a new region of the standard parameter space. Admitting in
addition a R-parity violating Yukawa coupling $\lambda'$, squarks are sought
through direct e-q fusion in a yet unexplored mass-coupling domain, taking into
account all possible squark decays. Squark masses up to 240 GeV are excluded
for $\lambda' \gtrsim \sqrt{4 \pi \alpha_{em}}$, depending only weakly on the
free model parameters.


title: Nonperturbative SUSY Gauge Theories with Soft Masses

abstract:
  After briefly reviewing the nonperturbative dynamics of N=1 supersymmetric
field theories, soft SUSY breaking mass terms are introduced into the SUSY
gauge theories and their effects on gauge symmetry breaking pattern are
studied. For $N_f<N_c$, we include the dynamics of the non-perturbative
superpotential and use the original (s)quark and gauge fields. For $N_f>N_c+1$,
we formulate the dynamics in terms of dual (s)quarks and a dual gauge group
SU(N_f-N_c). The mass squared of squarks can be negative triggering the
spontaneous breakdown of flavor and color symmetry. The general condition for
the stability of the vacuum is derived. We determine the breaking pattern,
derive the spectrum, and argue that the masses vary smoothly as one crosses
from the Higgs phase into the confining phase exhibiting the complmentarity.


title:
Resonant scattering of ultrahigh-energy neutrinos in the SU(3)_C X
  SU(3)_L X U(1)_N model

abstract:
  The lepton family-number changing \Delta L = 2 neutrino reactions in the
framework of the SU(3)_C X SU(3)_L X U(1)_N model with right-handed neutrinos
are presented. These processes have a much-enhanced cross section as a result
of s-channnel resonant bilepton Y production and they should be added to
ultrahigh-energy neutrino interactions.


title: Nonvanishing tensor polarization of sea quarks in polarized deuterons

abstract:
  We propose two new sources of a substantial tensor polarization of sea
partons in the deuteron: the diffractive nuclear shadowing which depends on the
alignment of nucleons in the polarized deuteron and the nuclear excess of pions
in the deuteron which is sensitive to the spin state of the deuteron. The
corresponding tensor structure function $b_{2}(x,Q^{2})$ rises towards small x
and we predict an about one per cent tensor asymmetry
$A_{2}(x,Q^{2})=b_{2}(x,Q^{2})/ F_{2d}(x,Q^{2})$ which by almost two orders in
magnitude exceeds the effect evaluated earlier in the impulse approximation.
The both mechanisms for tensor structure function break the sum rule $\int dx
b_{1}(x,Q^{2})=0$ suggested by Close and Kumano. We comment on the impact of
tensor polarization on the determination of the vector spin structure function
$g_{1d}(x,Q^{2})$ for the deuteron.


title:
Comparison of Renormalization-Group and Lattice Studies of the
  Electroweak Phase Transition

abstract:
  We compare the results of renormalization-group and lattice studies for the
properties of the electroweak phase transition. This comparison reveals the
mechanisms that underlie the phenomenology of the phase transition.


title: Electroweak Phase Transition in the Early Universe ?

abstract:
  Existence and properties of the electroweak phase transition in the early
universe depend strongly on the mass of the Higgs scalar M_H. There is
presumably no true symmetry restoration at high temperature. Nevertheless, a
first order phase transition occurs in the standard model for M_H smaller than
about 70 GeV. For a realistic scalar mass M_H larger than about 70 GeV the
transition to the high temperature regime is described by a crossover, due to
the strong electroweak gauge interactions for temperatures near and above the
critical temperature. Electroweak baryogenesis during this transition seems not
possible within the standard model. The observed baryon asymmetry in the
universe therefore implies the necessity of an extension of the standard model.


title: On the QED Radiator at Order $\alpha^3$

abstract:
  The ${\cal O} (\alpha^3)$ leading logarithmic contribution to the QED
radiator in the additive form is considered. The effect of the correction on
two-fermion physics at LEP1 and LEP2 is evaluated and critically compared with
the one of next-to-leading ${\cal O} (\alpha^2)$ corrections. A critical
comparison with existing estimates for the LEP1 energy range is also performed.
The ${\cal O} (\alpha^3)$ leading logarithmic corrections turn out to be
relevant in view of the experimental precision already reached at LEP1 and
foreseen at LEP2.


title:
Full QCD with Wilson Fermions: Recent Results from the SESAM
  Collaboration

abstract:
  We present recent results of SESAM's large scale lattice simulation of QCD
with two dynamical flavours of Wilson fermions. The emphasis is on future
prospects in the extraction of flavour-singlet matrix elements, i.e the
pi-nucleon sigma term, with dynamical configurations.


title: Neutrino Masses and Oscillations

abstract:
  New effects related to refraction of neutrinos in different media are
reviewed and implication of the effects to neutrino mass and mixing are
discussed. Patterns of neutrino masses and mixing implied by existing
hints/bounds are described. Recent results on neutrino mass generation are
presented. They include neutrino masses in SO(10) GUT's and models with
anomalous $U(1)$, generation of neutrino mass via neutrino-neutralino mixing,
models of sterile neutrino.


title: The $\Delta I = 1/2 $ Rule in the Light of Two-Dimensional QCD

abstract:
  We calculate in QCD$_2$ the ratios of baryonic matrix elements of $\Delta I =
2$ and $\Delta I = 0$ four-fermion operators, with a view to understanding
better the mechanism of $\Delta I = 1/2$ enhancement in QCD$_4$. We find
relatively small suppressions of both the scalar-scalar and vector-vector
$\Delta I = 2$ four-fermion operators. We discuss the possible implications of
these results, in view of a suggestion that gluon condensation may be an
important contributing factor in the $\Delta I = 1/2$ enhancement seen in
QCD$_4$. At the technical level, our calculation of the vector-vector operator
matrix element requires a treatment of the time dependence of the QCD$_2$
soliton which had not been developed in previous phenomenological calculations
within this model.


title:
Small-Angle Bhabha Scattering at LEP1. Analytical Results for
  Wide-Narrow Angular Acceptance

abstract:
  Analytical formulae for small-angle Bhabha scattering cross-section at LEP1
are given for the case of wide-narrow angular acceptance. Inclusive and
calorimeter event selections are considered. Numerical results are presented.


title: A Prediction for the 4-Loop \beta Function

abstract:
  We predict that the four-loop contribution \beta_3 to the QCD \beta function
in the MS-bar prescription is given by
  \beta_3\simeq 23,600(900) - 6,400(200) N_f + 350(70) N_f^2 + 1.5 N_f^3, where
N_f is the number of flavours and the coefficient of N_f^3 is an exact result
from large-N_f expansion. In the phenomenologically-interesting case N_f=3, we
estimate \beta_3 = (7.6 \pm 0.1) x 10^3. We discuss our estimates of the errors
in these QCD predictions, basing them on the demonstrated accuracy of our
method in test applications to the O(N) \Phi^4 theory, and on variations in the
details of our estimation method, which goes beyond conventional Pade
approximants by estimating and correcting for subasymptotic deviations from
exact results.


title: Deep Inelastic Scattering with Tagged Photons at HERA

abstract:
  We calculate cross-sections for neutral current deep inelastic scattering at
HERA with photon tagging. Both the exact lowest-order cross-section and a
leading logarithmic approximation of next-order corrections are calculated. The
latter amounts to less than 20% in a large kinematical range. The integrations
are performed numerically but without relying on Monte Carlo methods.


title: Numerical analysis of renormalon technique in quantum mechanics

abstract:
  We discuss the ways of extracting a low energy scale of an underlying theory
using high energy scattering data. Within an exactly solvable model of quantum
mechanics we analyze a technique based on introduction of nonperturbative power
corrections accounting for asymptotically small terms and an alternative
approach exploiting a modified running coupling constant of the model and
nonperturbative continuation of evolution equations into an infrared region.
Numerical estimates show that the latter is more efficient in approximating
low-energy data of the model.


title: Inverse Symmetry Breaking and the Exact Renormalization Group

abstract:
  We discuss the question of inverse symmetry breaking at non-zero temperature
using the exact renormalization group. We study a two-scalar theory and
concentrate on the nature of the phase transition during which the symmetry is
broken. We also examine the persistence of symmetry breaking at temperatures
higher than the critical one.


title: Soft Interactions and Diffraction Phenomena

abstract:
  Until the mystery of confinement is understood from the first principles, so
called `soft physics' remains an important area of research, providing valuable
information on underlying dynamics of strong interactions at long distances. In
this short review an attempt is made to summarize recent experimental results
on multiparticle production in e+e- annihilation and on diffraction at HERA.


title: Hard $m_t$ Corrections as a Probe of the Symmetry Breaking Sector

abstract:
  Non-decoupling effects related to a large $m_t$ affecting non-oblique
radiative corrections in vertices ($Z\bar{b}b$) and boxes ($B$-$\bar{B}$ mixing
and $\epsilon_K$) are very sensitive to the particular mechanism of spontaneous
symmetry breaking. We analyze these corrections in the framework of a chiral
electroweak standard model and find that there is only one operator in the
effective lagrangian which modifies the longitudinal part of the $W^+$ boson
without touching the oblique corrections. The inclusion of this operator
affects the $Z\bar{b}b$ vertex, the $B$-$\bar{B}$ mixing and the CP-violating
parameter $\epsilon_K$, generating interesting correlations among the hard
$m_t^4 \log m_t^2$ corrections to these observables, for example, the maximum
vertex $Z b\bar{b}$ correction allowed by low energy physics is about one
percent.


title: Dissipating Cosmic Vortons and Baryogenesis

abstract:
  Grand unified theories can admit cosmic strings with fermion zero modes which
result in the string carrying a current and the formation of stable remnants,
vortons. We consider theories in which the zero modes do not survive a
subsequent phase transition, for example the electroweak transition, resulting
in vorton dissipation. The dissipating vortons can create a baryon asymmetry.
We calculate the asymmetry produced, and show that it is maximised if the
vortons decay just before they dominate the energy density of the Universe. We
further bound the asymmetry produced by the late decay of any relic particle.


title: Outlook on Neutrino Physics

abstract:
  Some of the hot topics in neutrino physics are discussed, with particular
emphasis on neutrino oscillations. After proposing credibility criteria for
assessing various claimed effects, particular stress is laid on the solar
neutrino deficit, which seems unlikely to have an astrophysical explanation.
Comments are also made on the possibility of atmospheric neutrino oscillations
and on the LSND experiment, as well as cosmological aspects of neutrinos and
neutralinos. Several of the central issues in neutrino physics may be resolved
by the new generation of experiments now underway, such as CHORUS, NOMAD and
Superkamiokande, and in preparation, such as SNO and a new round of
accelerator- and reactor-based neutrino-oscillation experiments. At the end,
there is a brief review of ways in which present and future CERN experiments
may be able to contribute to answering outstanding questions in neutrino
physics.


title: A Comment on Heavy Quark Effective Fields

abstract:
  Effective fields defined in the heavy-quark effective theory to describe
heavy quarks in heavy-light hadrons are examined in some detail in the standard
formulation of a quantum field theory.


title: The Rare Top Decays $t \to b W^+ Z$ and $t \to c W^+ W^-$

abstract:
  The large value of the top quark mass implies that the rare top decays $t
\rightarrow b W^+ Z, s W^+ Z$ and $d W^+ Z$, and $t \rightarrow c W^+ W^-$ and
$u W^+ W^-$, are kinematically allowed decays so long as $m_t \ge m_W + m_Z +
m_{d_i} \approx 171.5 GeV + m_{d_i}$ or $m_t \ge 2m_W + m_{u,c} \approx 160.6
GeV + m_{u,c}$, respectively. The partial decay widths for these decay modes
are calculated in the standard model. The partial widths depend sensitively on
the precise value of the top quark mass. The branching ratio for $t\rightarrow
b W^+ Z$ is as much as $2 \times 10^{-5}$ for $m_t = 200 GeV$, and could be
observable at LHC. The rare decay modes $t \rightarrow c W^+ W^-$ and $u W^+
W^-$ are highly GIM-suppressed, and thus provide a means for testing the GIM
mechanism for three generations of quarks in the u, c, t sector.


title: Squarks and sphalerons

abstract:
  Electric charge and color breaking minima along third generation squark
directions do appear in the Minimal Supersymmetric Standard Model for
particular regions of the corresponding supersymmetric parameters $A_t$, $\mu$,
$\tan\beta$, $m_Q^2$ and $m_U^2$. We have studied possible instabilities of
electroweak sphalerons along non-trivial squark configurations. We have found
that instabilities along the latter lie in the region of parameter space where
the electroweak minimum is not the global one. Thus charge and color
conservation imply that the standard electroweak sphaleron is not destabilized
along squark directions.


title:
Modified Negative Binomial Description of the Multiplicity Distributions
  in Lepton-nucleon Scattering

abstract:
  It is shown that charged hadron multiplicity distributions in lepton-nucleon
scattering are fairly well described by the modified negative binomial
distribution in the energy range from 3-4 to 220 GeV. The energy behaviour of
the parameter k is similar to the dependence observed for e+e- annihilation.


title:
Phenomenological Parametrization of the Charged Particle Multiplicity
  Distributions in Restricted Rapidity Intervals in e+e- Annihilation into
  Hadrons and e+p Scattering at HERA

abstract:
  It is shown that charged hadron multiplicity distributions in restricted
(pseudo)rapidity intervals in e+e- annihilation and in e+p scattering at HERA
are quite well described by the modified negative binomial distribution and its
simple extension.


title: Small angle Bhabha scattering at LEP1. Wide-narrow angular acceptance

abstract:
  Analytical method is applied for description of the small angle Bhabha
scattering at LEP1. Inclusive event selection for asymmetrical wide-narrow
circular detectors is considered. The QED correction to the Born cross-section
is calculated with leading and next-to-leading accuracy in the second order of
perturbation theory and with leading one --- in the third order. All
contributions in the second order due to photonic radiative corrections and
pair production are calculated starting from essential Feynman diagrams. The
third order correction is computed by means of electron structure function.
Numerical results illustrate the analytical calculsations.


title: Database on the Net for Particle Correlations and Spectra

abstract:
  A fully interactive database is presented, which provides user-friendly
access to experimental results on single-particle spectra and two-particle
correlations (particle interferometry or HBT-effect). The database is available
on the World-Wide-Web at: http://www.quark.lu.se/~janus/hbt_home.html .


title: A Quantitative Analysis of Charmonium Suppression in Nuclear Collisions

abstract:
  Data from J/psi and psi' production in p-A collisions are used to determine
the cross section for absorption of pre-resonance charmonium in nuclear matter.
The J/psi suppression in O-Cu, O-U and S-U collisions is fully reproduced by
the corresponding nuclear absorption, while Pb-Pb collisions show an additional
suppression increasing with centrality. We study the onset of this change in
terms of hadronic comover interactions and conclude that so far no conventional
hadronic description can consistently account for all data. Deconfinement,
starting at a critical point determined by central S-U collisions, is in accord
with the observed suppression pattern.


title:
Associate $J/\psi + \gamma$ Production: A Clean Probe of Unpolarized and
  Polarized Gluon Densities

abstract:
  Color-octet contributions to the associate $J/\psi+\gamma$ production are
found to be negligible, compared to the ordinary color-singlet contribution.
Within the color-singlet model the $J/\psi+\gamma$ production in the leading
order is possible only through gluon-gluon fusion process. Therefore, the
associate $J/\psi+\gamma$ production remains to be useful as a clean channel to
probe the unpolarized and polarized gluon distribution inside proton (and
photon), and to study heavy quarkonia production mechanism. We discuss in
detail the associate production of $J/\psi+\gamma$ at $p \overline{p}$ (or
$pp$) and $ep$ colliders. By requiring the $J/\psi$ to decay into an $e^+e^-$
or $\mu^+ \mu^-$ pair, we end up with an exceptionally clean final state. This
process can therefore serve as a very clean probe of the gluon densities inside
the proton as well as the photon. Numerical results are presented for the
TEVATRON $p \overline{p}$ and HERA $ep$ colliders. This same mechanism can be
used to probe the polarized gluon content of the proton in polarized $p + p
(\bar p)$ collisions. We study in detail $J/\psi + \gamma$ production at both
polarized fixed target and polarized collider energies for RHIC.


title: A Comment on Totally Inclusive B0 Decays

abstract:
  We recall that the totally inclusive rate for B0 decays can yield information
on CP violation.


title:
A new interpretation of the proton-neutron bound state. The calculation
  of the binding energy

abstract:
  We treat the old problem of the proton-neutron bound state (the deuteron).
Using a new concept of incomplete (partial) annihilation process we derive a
formula for the binding energy of the deuteron, which does not contain any new
constant. Some implications of this new approach are discussed.


title: Heavy Ion Collisions at the LHC; the ALICE Experiment

abstract:
  ALICE (A Large Ion Collider Experiment) is a detector designed to exploit the
physics potential of nucleus-nucleus interactions at the LHC. Being a general
purpose experiment, it will allow a comprehensive study of hadrons, electrons,
muons and photons, produced in the collision of heavy nuclei, up to the highest
particle multiplicities anticipated (dNch/dy=8000). In addition to heavy
systems (Pb-Pb), we will study collisions at smaller energy densities by using
lower-mass ions (e.g. A~40). Reference data will be obtained from pp and
p-nucleus collisions. The central part of ALICE covers $|\eta| < 0.9$, and
consists of an inner tracker (ITS), a TPC and a particle identification array
(PID), all embedded in a large magnet with a weak solenoidal field. The
experiment is completed by two small area spectrometers in the barrel region
(an electromagnetic calorimeter, PHOS, and a high momentum PID detector,
HMPID), a forward muon spectrometer (2 degrees to 9.5 degrees) and a ZDC.


title: Hard probes in nucleus-nucleus collisions

abstract:
  The present knowledge on hard processes in the context of heavy ion
collisions is reviewed, with particular emphasis on J/psi production. The p-A
data on charmonia production from Fermilab experiments is shown to be in
excelent agreement with the p-A data collected at CERN. The simultaneous
analysis of all existing p-A data reaches a precision which allows us to rule
out some preconceived ideas, setting a good frame against which the data
collected with ion beams at CERN can be compared.


title: Nonleptonic Weak Decays of Bottom Baryons

abstract:
  Cabibbo-allowed two-body hadronic weak decays of bottom baryons are analyzed.
Contrary to the charmed baryon sector, many channels of bottom baryon decays
proceed only through the external or internal W-emission diagrams. Moreover,
W-exchange is likely to be suppressed in the bottom baryon sector.
Consequently, the factorization approach suffices to describe most of the
Cabibbo-allowed bottom baryon decays. We use the nonrelativistic quark model to
evaluate heavy-to-heavy and heavy-to-light baryon form factors at zero recoil.
When applied to the heavy quark limit, the quark model results do satisfy all
the constraints imposed by heavy quark symmetry. The decay rates and up-down
asymmetries for bottom baryons decaying into $(1/2)^++P(V)$ and $(3/2)^++P(V)$
are calculated. It is found that the up-down asymmetry is negative except for
$\Omega_b \to (1/2)^++P(V)$ decay and for decay modes with $\psi'$ in the final
state. The prediction $B(\Lambda_b \to J/\psi\Lambda)=1.6 \times 10^{-4}$ for
$|V_{cb}|=0.038$ is consistent with the recent CDF measurement. We also present
estimates for $\Omega_c \to (3/2)^++P(V)$ decays and compare with various model
calculations.


title: Nonperturbative Effects in the Nonrelativistic Hadron Scattering

abstract:
  Starting from the gauge-invariant quark-antiquark Green function the
expression for the nonrelativistic meson scattering amplitude is obtained and
the nonperturbative form of this amplitude is discussed.


title:
Electroweak baryogenesis from chargino transport in the supersymmetric
  model

abstract:
  We study the baryon asymmetry of the universe in the supersymmetric standard
model (SSM). At the electroweak phase transition, the fermionic partners of the
charged SU(2) gauge bosons and Higgs bosons are reflected from or transmitted
to the bubble wallof the broken phase. Owing to a physical complex phase in
their mass matrix, these reflections and transmissions have asymmetries between
CP conjugate processes. Equilibrium conditions in the symmetric phaseare then
shifted to favor a non-vanishing value for the baryon number density, which is
realized through electroweak anomaly. We show that the resultant ratio of
baryon number to entropy is consistent with its present observed value within
reasonable ranges of SSM parameters, provided that the CP-violating phase
intrinsic in the SSM is not much suppressed. The compatibility with the
constraints on the parameters from the electric dipole moment of the neutron is
also discussed.


title:
The Space-Time Picture of the Wee Partons and the AGK Cutting Rules in
  Perturbative QCD

abstract:
  We discuss the space-time picture of scattering amplitudes with single and
double ladder exchange in perturbative QCD. Particular emphasis is given to the
Abramovsky Gribov Kanchelli (AGK) rules which describe the relative
contributions of the diffractive dissociation and processes with other
multiplicities to the elastic scattering amplitude. Inside the Pomeron Pomeron
interaction vertices we find a new matrix which describes the transition from
one s-cut to another and which goes beyond the original the AGK rules.


title: Heavy neutrinos production and decay in future $e^+e^-$ colliders

abstract:
  The production of heavy and light neutrinos in $e^+e^-$ future colliders is
considered. The cross section for the process $e^+e^- \rightarrow \nu N$ and
then the heavy neutrino decay $N \rightarrow W^{\pm} e^{\mp}$ is determined for
experimentally possible values of mixing matrix elements. The bound on the
heavy neutrino-electron mixing is estimated in models without right-handed
currents. The role of neutrino CP eigenvalues and the mass of the lightest
Higgs particle are investigated. The angular distribution of charged leptons in
the total CM frame resulting from the heavy neutrino decay and from the main
$W^+W^-$ production background process are briefly compared.


title:
Chiral dynamics of rare eta decays and virtual Compton scattering off
  the nucleon

abstract:
  Two different topics relevant for DA$\Phi$NE and CEBAF, respectively, are
covered. First we analyze the rare radiative eta decay mode
$\eta\to\pi\pi\gamma\gamma$ within the framework of chiral perturbation theory
at ${\cal O}(p^4)$. We then discuss virtual Compton scattering off the nucleon
at low energies. Predictions for the two spin-independent generalized
polarizabilities are shown.


title: SUSY and Such

abstract:
  Introductory lectures on the phenomenology of the minimal supersymmetric
Standard Model. The emphasis is on general signatures for supersymmetry and on
the motivation for constructing supersymmetric models. These lectures are
intended for experimental graduate students.


title: Chiral Symmetry: Pion-Nucleon Interactions in Constituent Quark Models

abstract:
  We study the interactions of an elementary pion with a nucleon made of
constituent quarks and show that the enforcement of chiral symmetry requires
the use of a two-body operator, whose form does not depend on the choice of the
pion-quark coupling. The coordinate space NN effective potential in the pion
exchange channel is given as a sum of terms involving two gradients, that
operate on both the usual Yukawa function and the confining potential. We also
consider an application to the case of quarks bound by a harmonic potential and
show that corrections due to the symmetry are important.


title:
Coherent amplification of classical pion fields during the cooling of
  droplets of quark plasma

abstract:
  In the framework of the linear sigma model, we study the time evolution of a
system of classical $\sigma$ and pion fields coupled to quarks. For this
purpose we solve numerically the classical transport equation for relativistic
quarks coupled to the nonlinear Klein-Gordon equations for the meson fields. We
examine evolution starting from variety of initial conditions corresponding to
spherical droplets of hot quark matter, which might mimic the behaviour of a
quark plasma produced in high-energy nucleus-nucleus collisions. For large
droplets we find a strong amplification of the pion field that oscillates in
time. This leads to a coherent production of pions with a particular isospin
and so would have similar observable effects to a disoriented chiral condensate
which various authors have suggested might be a signal of the chiral phase
transition. The mechanism for amplification of the pion field found here does
not rely on this phase transition and is better thought of as a "pion laser"
which is driven by large oscillations of the $\sigma$ field.


title: More missing VEV mechanism in supersymmetric SO(10) model

abstract:
  The anomalous gauge $U(1)_A$ symmetry which could emerge in the context of
the string theories can be very useful ingredient towards builting the complete
supersymmetric SO(10) model. We present an example of the $SO(10)\times U(1)_A$
model which provides the ``all order'' solution to the doublet-triplet
splitting problem via the missing VEV mechanism -- the Planck scale corrections
only can induce the mu-term naturally of order 1 TeV. An interesting feature of
this model is that all relevant GUT scale VEVs are defined by the single
dimensional parameter in the Higgs superpotential, so that the SO(10) symmetry
breaks down to the MSSM practically at one step, without intermediate stages.
The colour Higgsino mediated d=5 operators can be naturally suppressed. We also
extend the model by implementing $U(1)_A$ as a horizontal symmetry for
explaining the fermion mass and mixing pattern, and obtain a predictive texture
for fermion masses. This model implies a moderate value of $\tan\beta$ ($\sim
6-10$) and leads to five predictions for the low energy observables. It also
leads to the neutrino masses and mixing pattern that could naturally explain
both the atmospheric and solar neutrino problems. In addition, a remarkable
interplay of the SO(10) and $U(1)_A$ symmetries guarantees an automatic R
parity conservation at any order in $M_P^{-1}$, and also suppresses the Planck
scale induced B and L violating d=5 operators to the needed level.


title:
Transverse momentum dependence in the perturbative calculation of pion
  form factor

abstract:
  By reanalysing transverse momentum dependence in the perturbative calculation
of pion form factor an improved expression of pion form factor which takes into
account the transverse momentum dependenc in hard scattering amplitude and
intrinsic transverse momentum dependence associated with pion wave functions is
given to leading order, which is available for momentum transfers of the order
of a few GeV as well as for $Q \to \infty$. Our scheme can be extended to
evaluate the contributions to the pion form factor beyond leading order.


title: Thermal Photon Emission from QGP fluid

abstract:
  We compare the numerical results of thermal photon distribution from the hot
QCD matter produced by high energy nuclear collisions, based on hydrodynamical
model, with the recent experimental data obtained by CERN WA80. Through the
asymptotic value of the slope parameter of the transverse momentum
distribution, we discuss the characteristic temperature of the QCD fluid.


title: Model (In)dependent Features of the Hard Pomeron

abstract:
  We discuss the small-x behaviour of the next-to-leading BFKL equation,
depending on various smoothing out procedures of the running coupling constant
at low momenta. While scaling violations (with resummed and calculable
anomalous dimensions) turn out to be always consistent with the renormalization
group, we argue that the nature and the location of the so-called hard Pomeron
are dependent on the smoothing out procedure, and thus really on soft hadronic
interactions.


title: Jet cross sections at next-to-leading order

abstract:
  We briefly summarize theoretical methods for carrying out QCD calculations to
next-to-leading order in perturbation theory. In particular, we describe a new
general algorithm that can be used for computing arbitrary jet cross sections
in arbitrary processes and can be straightforwardly implemented in
general-purpose Monte Carlo programs.


title:
Electroweak Effective Charges and their relation to Physical Cross
  Sections

abstract:
  In quantum electrodynamics with fermions f = e,\mu..., knowledge of the
vacuum polarization spectral function determined from the tree level e^+e^- ->
f^+f^- cross sections, together with a single low energy measurement of the
fine structure constant \alpha, enables the construction of the one-loop
effective charge \alpha_eff(q^2) for all q^2. It is shown how an identical
procedure can be followed in the electroweak sector of the Standard Model to
construct three gauge-, scale- and scheme-independent one-loop electroweak
effective charges and an effective weak mixing angle from the tree level e^+e^-
-> W^+W^-, ZH and e^+\nu_e -> W^+Z, W^+\gamma, W^+H differential cross
sections, together with three low energy measurements, which may be chosen to
be \alpha and the masses of the W and Z bosons. It is found that the
corresponding proper self-energy-like functions thus constructed are identical
to those obtained in the pinch technique framework. In this way, it is shown
how the concept of effective charges in the electroweak Standard Model is as
well-defined and unique as in quantum electrodynamics.


title: Breaking SU3f Spontaneously Down to Isospin

abstract:
  The mechanism where flavour symmetry is broken spontaneously is demonstated
for a model involving nonets of pseudoscalar and vector mesons. Degenerate bare
nonets of vector and pseudoscalar mesons coupling sufficiently strongly to each
others lead to unstable self-consistency equations, such that the SU3$_f$
symmetric spectrum breaks down into a stable isospin symmetric mass spectrum
similar to the physical spectrum.


title:
Interpolating the Stage of Exponential Expansion in the Early Universe:
  a possible alternative with no reheating

abstract:
  In the standard picture, the inflationary universe is in a supercooled state
which ends with a short time, large scale reheating period, after which the
universe goes into a radiation dominated stage. An alternative is proposed here
in which the radiation energy density smoothly decreases all during an
inflation-like stage and with no discontinuity enters the subsequent radiation
dominated stage. The scale factor is calculated from standard Friedmann
cosmology in the presence of both radiation and vacuum energy density. A large
class of solutions confirm the above identified regime of non-reheating
inflation-like behavior for observationally consistent expansion factors and
not too large a drop in the radiation energy density. One dynamical realization
of such inflation without reheating is from warm inflation type scenarios.
However the solutions found here are properties of the Einstein equations with
generality beyond slow-roll inflation scenarios. The solutions also can be
continuously interpolated from the non-reheating type behavior to the standard
supercooled limit of exponential expansion, thus giving all intermediate
inflation-like behavior between these two extremes. The temperature of the
universe and the expansion factor are calculated for various cases.
Implications for baryongenesis are discussed. This non-reheating,
inflation-like regime also appears to have some natural features for a universe
that is between nearly flat and open.


title: Tree-unitary sigma models and their application to strong WW scattering

abstract:
  Sigma models are exhibited which have tree amplitudes for Goldstone boson
scattering that satisfy elastic unitarity exactly. The models have imaginary
coupling constants and the scalar propagators have poles on the imaginary axis
in the complex p^2 plane. They are equivalent to K-matrix models, which are ad
hoc unitarizations of low energy theorems for Goldstone boson scattering that
have been used recently to describe strong WW scattering. The sigma model
formulation of the K-matrix models may be used to estimate directly the effect
of strong WW scattering on low energy radiative corrections.


title: Dynamical Perturbation Theory and the Auxiliary Field Method

abstract:
  By introducing auxiliary fields, which by their quantum numbers vanish in
perturbation theory, we relate the dynamical perturbation theory of Pagels and
Stokar and a successful gauged nonlocal constituent quark model to $U(N)$ gauge
theory and to QCD. This sheds light on the duality between quark models and
resonance models. We then derive the effective action in the loop expansion
without dropping cubic and quartic gluon couplings.


title: The gauge technique for heavy quarks

abstract:
  It is possible to determine a propapagator for heavy quarks to order 1/m in
any covariant gauge, which applies universally to all quarks, by using the
gauge technique. The leading behaviour is given by a _0F_2 function and the
result is reliable in the infrared limit, accounting for soft-gluon corrections
to the quark in internal loops.


title:
Constraints on Energy Independent Solutions of the Solar Neutrino
  Problem

abstract:
  We analyze the latest published solar neutrino data assuming an arbitrary
neutrino oscillation/conversion mechanism suppresses the electron neutrino flux
from the Sun independent of energy. For oscillations/transitions into active
(sterile) neutrinos such mechanisms are ruled out at 99.96 (99.9997) % C.L.
assuming the standard solar model by Bahcall and Pinnsoneault '95 correctly
predicts all solar neutrino fluxes within their estimated uncertainties. Even
if one allows for $^8{\rm B}$ and $^7{\rm Be}$ solar neutrino fluxes that are
vastly different from the ones in contemporary standard solar models these
mechanisms are strongly disfavored by the data.


title: An Introduction to Light-Front Dynamics for Pedestrians

abstract:
  In these lectures we hope to provide an elementary introduction to selected
topics in light-front dynamics. Starting from the study of free field theories
of scalar boson, fermion, and massless vector boson, the canonical field
commutators and propagators in the instant and front forms are compared and
contrasted. Poincare algebra is described next where the explicit expressions
for the Poincare generators of free scalar theory in terms of the field
operators and Fock space operators are also given. Next, to illustrate the idea
of Fock space description of bound states and to analyze some of the simple
relativistic features of bound systems without getting into the wilderness of
light-front renormalization, Quantum Electrodynamics in one space - one time
dimensions is discussed along with the consideration of anomaly in this model.
Lastly, light-front power counting is discussed. One of the consequences of
light-front power counting in the simple setting of one space - one time
dimensions is illustrated using massive Thirring model. Next, motivation for
light-front power counting is discussed and power assignments for dynamical
variables in three plus one dimensions are given. Simple examples of tree level
Hamiltonians constructed by power counting are provided and finally the idea of
reducing the number of free parameters in the theory by appealing to symmetries
is illustrated using a tree level example in Yukawa theory.


title: The exact parity symmetric model and big bang nucleosynthesis

abstract:
  The assumption of exact, unbroken parity symmetry leads directly to a simple
predictive resolution of the atmospheric and solar neutrino puzzles. This is
because the existence of this symmetry implies the existence of a set of mirror
neutrinos which must mix maximally with the known neutrinos if neutrinos have
mass. The maximal mixing of the electron neutrino with the mirror electron
neutrino with $3 \times 10^{-10} eV^2 < |\delta m^2| < 10^{-3} eV^2$ eads to a
predicted reduction of the solar neutrino flux by a factor of 2, which is in
quite good agreement with the experiments. The maximal mixing of the muon
neutrino with the mirror muon neutrino with $|\delta m^2| \simeq 10^{-2} eV^2$
also solves the atmospheric neutrino puzzle. We show that there is a
significant range of parameters where these solutions are not in conflict with
standard Big Bang Nucleosynthesis when the creation of lepton asymmetry due to
neutrino oscillations is taken into account.


title: Spin-3/2 fields in the heavy-baryon effective theory

abstract:
  In the framework of the path integral approach we develop the velocity
component formalism for spin-1/2 and -3/2 baryons coupled with pseudoscalar
mesons in the limit of heavy baryons.
  Starting from the most general chiral meson-baryon lagrangian including the
invariance of spin-3/2 fields under point transformation we detail various
problems in integrating out the heavy velocity components in the baryon fields
and derive the effective lagrangian for the light components up to
O(1/M_{baryon}).


title: Tests of CPT

abstract:
  A few remarks concerning theoretical suggestions and experimental tests of
CPT during 1980's - 1990's. Is it worth to search for the particle-antiparticle
mass differences in sectors other than $K^0\bar{K}^0$?


title: Fundamental Role of Experiments in High Energy Physics

abstract:
  An introductory talk at a Meeting on results and prospects of collaboration
of Russian research organizations with European organization for nuclear
research (CERN), which took place at the Ministry of science and technical
policy of Russia on 8 July, 1996.


title: Fundamental Constants of Nature

abstract:
  A brief review, from basic atomic constants to "Mendeleev Table" of leptons,
quarks, fundamental bosons, and then to superunification of all forces and
particles.


title:
Next-to-Leading Order Evolution of Polarized and Unpolarized
  Fragmentation Functions

abstract:
  We determine the two-loop 'time-like' Altarelli-Parisi splitting functions,
appearing in the next-to-leading order Q^2-evolution equations for
fragmentation functions, via analytic continuation of the corresponding
'space-like' splitting functions for the evolution of parton distributions. We
do this for the case of unpolarized fragmentation functions and - for the first
time - also for the functions describing the fragmentation of a longitudinally
polarized parton into a longitudinally polarized spin-1/2 hadron such as a
Lambda baryon. Our calculation is based on the method proposed and employed by
Curci, Furmanski and Petronzio in the unpolarized case in which we confirm
their results.


title: Limitations on using the operator product expansion at small values of x

abstract:
  Limits on the regions of $Q^2$ and x where the operator product expansion
canbe safely used, at small values of x are given. For a fixed large $Q^2$
there is an $x_0(Q^2)$ such that for Bjorken x-values below $x_0$ the operator
product expansion breaks down with significant nonperturbative corrections
occurring in the leading twist coefficient and anomlous dimension functions due
to diffusion of gluons to small values of transverse momentum.


title: Large N_c Limit of Spin-Flavor Breaking in Excited Baryon Levels

abstract:
  Spin-flavor symmetry breaking in the levels of excited Baryons are studied to
leading order in the 1/$N_c$ expansion. This breaking occurs at zeroth order.
For non-strange Baryons with a single quark excited, it is shown that to first
order of perturbation theory the breaking is given by one 1-body operator
(spin-orbit), and three 2-body operators, all involving the orbital angular
momentum of the excited quark. Higher-body operators can be reduced to that set
of operators. As illustration, p-wave Baryons are briefly discussed.


title: New Astrophysical Constraints on the Mass of the Superlight Gravitino

abstract:
  In some supergravity models, the superlight gravitino is accompanied by a
light weakly coupled scalar (S) and pseudo-scalar (P) particle. The coupling of
these particles to matter is inversely proportional to the product of the
gravitino mass and the Planck mass. As a result, their emission from the stars
and supernovae via the photon electron scattering reaction for certain ranges
of the gravitino mass can become the dominant energy loss mechanism in
contradiction with observations thereby ruling out those mass values for the
gravitino. For scalar and/or pseudo-scalar masses between 10 MeV and a keV, the
SN1987A observations exclude the gravitino mass range from 0.03 eV to 30 eV
whereas if the S/P masses are less than a keV, constraints of stellar energy
loss can exclude the gravitino masses ranging from $3\times 10^{-6}$ eV to 50
eV for the photino mass of 100 GeV. We also find that for S/P mass less than an
MeV, Big Bang Nucleosynthesis constraints imply a gravitino mass larger than
one eV. These are the most stringent bounds to date on the gravitino mass in
this class of models.


title: Z Physics Constraints on Vector Leptoquarks

abstract:
  We analyze the constraints on vector leptoquarks coming from radiative
corrections to $Z$ physics. We perform a global fitting to the LEP data
including the oblique and non-universal contributions of the most general
effective Lagrangian for vector leptoquarks, which exhibits the $SU(2)_L \times
U(1)_Y$ gauge invariance. We show that the $Z$ physics leads to stronger bounds
on second and third generation vectors leptoquarks than the ones obtained from
low energy and the current collider experiments.


title:
Theoretical Aspects of $\tau \to K h (h) \nu_\tau$ Decays and
  Experimental Comparisons

abstract:
  Predictions for decay rates and distributions for $\tau$ decays into final
states with kaons are discussed and compared with recent measurements. Special
emphasis is put on new constraints for the vector current contribution in the
$KK\pi$ decay modes. For the $K\pi\pi$ modes, disagreements with the
experimental results can be traced back to the $K_1$ widths.


title:
Evolution of chiral-odd spin-independent fracture functions in Quantum
  Cromodynamics

abstract:
  We construct the evolution equations for the twist-3 chiral-odd spin
independent fracture functions in QCD. The Gribov-Lipatov reciprocity relation
is fulfilled at the one-loop level for the quasi-partonic two-particle cut
vertices only. It is found that the rang of the anomalous dimensions matrix is
infinite for any given moment of the three-parton fracture function as
distinguished from the case of DIS-distributions where the rang of the matrix
was finite and increases with the number of the moment. In the multicolour
limit $N_c \to \infty$ the evolution equation for the quark-gluon-quark
correlation function decouples from another equation in the system and becomes
homogeneous provided we discard the quark mass effects. This fact provides an
opportunity to find its analytic solution explicitly in nonlocal form similarly
to the DIS.


title: Probing Contact Interactions at High Energy Lepton Colliders

abstract:
  Fermion compositeness and other new physics can be signalled by the presence
of a strong four-fermion contact interaction. Here we present a study of
$\ell\ell qq$ and $\ell\ell\ell'\ell'$ contact interactions using the
reactions: $\ell^+ \ell^- \to \ell'^+\ell'^-,b\bar b, c\bar c$ at future
$e^+e^-$ linear colliders with $\sqrt s=0.5-5$ TeV and $\mu^+\mu^-$ colliders
with $\sqrt s=0.5,4$ TeV. We find that very large compositeness scales can be
probed at these machines and that the use of polarized beams can unravel their
underlying helicity structure.


title: Dashen's theorem and electromagnetic masses of the mesons

abstract:
  Employing $U(3)_L\times U(3)_R$ chiral field theory, we find that Dashen's
theorem, which holds for pseudoscalar mesons, can be generalized to the sector
of axial-vector mesons, however, fails for vector mesons.


title: Three-Flavor Analysis of Neutrino Mixing with and without Mass Hierarchy

abstract:
  I summarize the results of barely model-dependent phenomenological analyses
of the structure of the neutrino flavor mixing. The analyses are based on the
three-flavor mixing framework without sterile neutrinos and utilize the hints
from solar and atmospheric neutrino observations as well as that from mixed
dark matter cosmology. It will be demonstrated that the features of the
analysis is sharply distinguished by the two cases (I) with and (II) without
dark matter mass scale, and by whether one (or two) mass is dominant (OMD) or
the three states are almost degenerate (ADN). The global features of the
neutrino mixing is illuminated for these different mass patterns.