title:
New and Strong Constraints on the Parameter Space of the MSSM from
  Charge and Color Breaking Directions

abstract:
  Although the possible existence of dangerous charge and color breaking (CCB)
directions in the MSSM has been known since the early 80's, only particular
directions in the field-space have been considered, thus obtaining necessary
but not sufficient conditions to avoid dangerous CCB minima. Furthermore, the
radiative corrections to the potential were not normally included in a proper
way, often leading to an overestimation of the restrictive power of the bounds.
It turns out that when correctly evaluated, the ``traditional" CCB bounds are
very weak. I give here a brief survey of recent results on this subject, which
represent a complete analysis, showing that the new CCB bounds are very strong
and, in fact, there are extensive regions in the parameter space that become
forbidden. This produces important bounds, not only on the value of $A$, but
also on the values of $B$ and $M_{1/2}$. The form of strongest one of the new
bounds, the so called UFB-3 bound, is explicitely given.


title: Natural flavour mixing in the MSSM and $\mu --> e, \gamma$

abstract:
  In the absence of any additional assumption it is natural to conjecture that
sizeable flavour-mixing mass entries, $\Delta m^2$, may appear in the mass
matrices of the scalars of the MSSM, i.e. $\Delta m^2\sim O(m^2)$. This flavour
violation can still be reconciled with the experiment if the gaugino mass,
$M_{1/2}$, is large enough to yield (through the renormalization group running)
a sufficiently small $\Delta m^2 / m^2$ at low energy. This leads to a gaugino
dominance framework (i.e. $M_{1/2}^2\gg m^2$), which permits a remarkably
model--independent analysis. We study this possibility focussing our attention
on the $\mu\rightarrow e,\gamma$ decay. In this way we obtain very strong and
general constraints, in particular $\frac{M_{1/2}^2}{\Delta m} \simgt 34\ {\rm
TeV}$.


title: Multiple Interactions in Two-Photon Collisions

abstract:
  We compute cross sections for events where two pairs of partons scatter off
each other in the same $\gamma\gamma$ reaction, giving rise to at least 3
high--{\mbox{$p_T^{}$}} jets. Unlike in {\mbox{$p \bar p$}}\ collisions we find
the signal to lie well above the background from higher order QCD processes. If
the usual ``eikonaliztion" assumption is correct, the signal should be readily
observable at LEP2, and might already be detectable in data taken at TRISTAN.


title:
Looking for Invisibly Decaying Higgs Bosons through the Final State
  $b\bar{b}+\protect\ptmis$

abstract:
  We study the potential of LEP II to unravel the existence of invisibly
decaying Higgs bosons through the reaction $e^+ e^- \rightarrow b\bar{b} +
\ptmis$. We perform our analyses in a model independent way and our results
show that LEP II is capable of discovering such a Higgs for a wide range of
masses and couplings.


title: Improved QCD Form Factor Constraints and Lambda_b --> Lambda_c l nu

abstract:
  We construct model-independent parametrizations of the individual QCD form
factors relevant to Lambda_b --> Lambda_c l nu decays. These results follow
from dispersion relations and analyticity, and incorporate an improvement in
the technique that reduces the number of necessary parameters. To describe most
form factors with 5%--10% accuracy over the entire kinematic range, three
parameters are necessary, one of which is its normalization at zero recoil. We
also apply the improvement to meson decays, and find, using the heavy quark
form factor normalization, that almost every B --> D l nu and B --> D^* l nu
form factor is well-described by a single-variable parametrization. B --> pi l
nu requires a total of only 3 to 5 parameters, depending on the desired
accuracy.


title: Ultrahigh-Energy Neutrino Interactions

abstract:
  Cross sections for the interactions of ultrahigh-energy neutrinos with
nucleons are evaluated in light of new information about nucleon structure
functions. For $10^{20}$--eV neutrinos, the cross section is about 2.4 times
previous estimates. We also review the cross sections for neutrino interactions
with atomic electrons. Some consequences for interaction rates in the Earth and
for event rates from generic astrophysical sources in large-scale detectors are
noted.


title: Hard Dense Loops in a Cold Non-Abelian Plasma

abstract:
  Classical transport theory is used to study the response of a non-Abelian
plasma at zero temperature and high chemical potential to weak color
electromagnetic fields. In this article the parallelism between the transport
phenomena occurring in a non-Abelian plasma at high temperature and high
density is stressed. Particularly, it is shown that at high densities it is
also possible to relate the transport equations to the zero-curvature condition
of a Chern-Simons theory in three dimensions, even when quarks are not
considered ultrarelativistic. The induced color current in the cold plasma can
be expressed as an average over angles, which represent the directions of the
velocity vectors of quarks having Fermi energy. From this color current it is
possible to compute $n$-point gluonic amplitudes, with arbitrary $n$. It is
argued that these amplitudes are the same as the ones computed in the high
chemical potential limit of QCD, that are then called hard dense loops. The
agreement between the two different formalisms is checked by computing the
polarization tensor of QED due to finite density effects in the high density
limit.


title:
Neutralinos and Higgs Bosons in the Next-To-Minimal Supersymmetric
  Standard Model

abstract:
  The purpose of this paper is to present a complete and consistent list of the
Feynman rules for the vertices of neutralinos and Higgs bosons in the
Next-To-Minimal Supersymmetric Standard Model (NMSSM), which does not yet exist
in the literature. The Feynman rules are derived from the full expression for
the Lagrangian and the mass matrices of the neutralinos and Higgs bosons in the
NMSSM. Some crucial differences between the vertex functions of the NMSSM and
the Minimal Supersymmetric Standard Model (MSSM) are discussed.


title:
The Generalized Crewther Relation in QCD and its Experimental
  Consequences

abstract:
  We use the BLM scale-fixing prescription to derive a renormalization-scheme
invariant relation between the coefficient function for the Bjorken sum rule
for polarized deep inelastic scattering and the $R$-ratio for the $e^+e^-$
annihilation cross section. This relation provides a generalization of the
Crewther relation to non-conformally invariant gauge theories. The derived
relations allow one to calculate unambiguously without renormalization scale or
scheme ambiguity the effective charges of the polarized Bjorken and the
Gross-Llewellen Smith sum rules from the experimental value for the effective
charge associated with $R$-ratio. Present data are consistent with the
generalized Crewther relations, but measurements at higher precision and
energies will be needed to decisively test these fundamental relations in QCD.


title:
Isocurvature and Adiabatic Fluctuations of Axion in Chaotic Inflation
  Models and Large Scale Structure

abstract:
  In the chaotic inflation models, quantum fluctuations for axion fields lead
to the overproduction of domain walls and too large isocurvature fluctuations
which is inconsistent with the observations of cosmic microwave background
anisotropies. These problems are solved by assuming a very flat potential for
the Peccei-Quinn scalar. As the simplest possibility, we consider a model where
the Peccei-Quinn scalar is an inflaton itself and show that the isocurvature
fluctuations can be comparable with the adiabatic ones. We investigate
cosmological implications in the case that both adiabatic and isocurvature
fluctuations exist and find that the amplitude of the matter spectrum becomes
smaller than that for the pure adiabatic case. This leads to relatively high
bias parameter ($b \simeq 2$) which is favoured by the current observations.


title: Electroweak corrections to the muon anomalous magnetic moment

abstract:
  The bosonic two-loop electroweak radiative corrections to the muon's
anomalous magnetic moment, $a_\mu\equiv (g_\mu-2)/2$, are presented. We find
$\Delta a_\mu^{\rm EW}({\rm 2\,loop\, bosonic})/ a_\mu^{\rm EW}({\rm
1\,loop})\approx {\alpha\over \pi}\left(-3.6 \ln\left({M_W^2\over
m_\mu^2}\right) +0.10 \right)\approx -0.11$ for $M_{\rm Higgs}\approx 250$ GeV.
Combining that result with our previous two-loop fermionic calculation, we
obtain an overall 22.6\% reduction in $a_\mu^{\rm EW}$ from $195\times
10^{-11}$ to $151(4)\times 10^{-11}$. Implications for the full standard model
prediction and an upcoming high precision measurement of $a_\mu$ are briefly
discussed. We also give the two-loop electroweak corrections to the anomalous
magnetic moments of electron and tau lepton; they result in a reduction of the
one-loop estimates by 35\% and 15\%, respectively.


title: Jets and Quantum Field Theory

abstract:
  We discuss quantum-field-theoretic interpretation of the family of
observables (the so-called C-algebra) introduced in [ F.V.Tkachov: Preprint
FERMILAB-PUB-95/191-T] for a systematic description of multijet structure of
multiparticle final states at high energies. We argue that from the point of
view of general quantum field theory, all information about the multijet
structure is contained in the values of a family of multiparticle quantum
correlators that can be expressed in terms of the energy-momentum tensor.


title: $\gamma\gamma$ Event Generators

abstract:
  The report from the working group on '\gamma\gamma Event Generators' of the
LEP 2 workshop


title: Direct and Resolved Pomeron in Rapidity Gap Cross Sections

abstract:
  We investigate the effect of a direct pomeron coupling to quarks on inclusive
jet production in DIS and photoproduction. The direct pomeron coupling
generates a point-like contribution to the diffractive part of the structure
function $F_2$, which is analysed on the basis of the latest H1 and ZEUS data.
Our model assumptions for the pomeron structure are consistent with the
measured data.


title: Colour Reconnections and Rapidity Gaps

abstract:
  The success of recently proposed models for describing rapidity-gap events in
DIS at HERA, in terms additional colour exchange between the struck system and
the proton remnant in boson-gluon fusion events, are found to rely heavily on
the absence or artificial suppression of perturbative gluon emission in the
forward region. A model without such suppression is presented, which cannot
describe the rapidity-gap events without a pomeron-inspired mechanism.


title:
The $\gamma\gamma\to\pi^0\pi^0$ and $\eta\to\pi^0\gamma\gamma$
  Transitions in the Extended NJL Model

abstract:
  We calculate within the Extended Nambu--Jona-Lasinio model the leading in
$1/N_c$ contribution to $\gamma\gamma\to\pi^0\pi^0$ to all orders in the
external momenta and quark masses. This result is then combined with the known
two-loop Chiral Perturbation Theory and compared with the data and other
calculations. A technical difficulty in the same calculation beyond order $p^6$
for $\eta\to\pi^0\gamma\gamma$ is identified and for this decay results up to
order $p^6$ are presented.


title:
Chiral Symmetry Restoration at Finite Temperature and Chemical Potential
  in the Improved Ladder Approximation

abstract:
  The chiral symmetry of QCD is studied at finite temperature and chemical
potential using the Schwinger-Dyson equation in the improved ladder
approximation. We calculate three order parameters; the vacuum expectation
value of the quark bilinear operator, the pion decay constant and the quark
mass gap. We have a second order phase transition at the temperature $T_c=169$
MeV along the zero chemical potential line, and a first order phase transition
at the chemical potential $\mu_c=598$ MeV along the zero temperature line. We
also calculate the critical exponents of the three order parameters.


title: QCD Sum Rules Calculation of the Singlet Axial Constant

abstract:
  We analyze the singlet axial form factor of the proton for small momentum
transferred in the framework of QCD sum rules using the interpolating nucleon
current which explicitly accounts for the gluonic degrees of freedom. As a
result we come to the quantitative description of the singlet axial constant:
G_A(0)=0.2. The bilocal power corrections play the most important role in the
analysis.


title: Gluon Contribution to the Transverse Spin Structure Function g2

abstract:
  We consider the twist-3 gluon contribution to the transverse spin structure
function $g_2$.We find that the Burkhardt-Cottingham sum rule is satisfied. The
additional {\it nonlocal} operators appear in the moments of g2 which were
absent in previous analysis of Bukhvostov, Kuraev and Lipatov.


title:
How Well Do We (and Will We) Know Solar Neutrino Fluxes and Oscillation
  Parameters?

abstract:
  Assuming neutrino oscillations occur, the pp electron neutrino flux is
uncertain by at least a factor of two, the ${\rm ^8B}$ flux by a factor of
five, and the ${\rm ^7Be}$ flux by a factor of forty-five. Calculations of the
expected results of future solar neutrino experiments (SuperKamiokande, SNO,
BOREXINO, ICARUS, HELLAZ, and HERON) are used to illustrate the extent to which
these experiments will restrict the range of the allowed neutrino mixing
parameters. We present an improved formulation of the ``luminosity constraint''
and show that at 95\% confidence limit this constraint establishes the best
available limits on the rate of creation of pp neutrinos in the solar interior
and provides the best upper limit to the ${\rm ^7Be}$ neutrino flux.


title:
Polarized inclusive leptoproduction, $\ell N \to hX$, and the hadron
  helicity density matrix, $\rho(h)$: possible measurements and predictions

abstract:
  We discuss the production of hadrons in polarized lepton nucleon interactions
and in the current jet fragmentation region; using the QCD hard scattering
formalism we compute the helicity density matrix of the hadron and show how its
elements, when measurable, can give information on the spin structure of the
nucleon and the spin dependence of the quark fragmentation process. The cases
of $\rho$ vector mesons and $\Lambda$ baryons are considered in more details
and, within simplifying assumptions, some estimates are given.


title: Weak Decays Beyond Leading Logarithms

abstract:
  We review the present status of QCD corrections to weak decays beyond the
leading logarithmic approximation including particle-antiparticle mixing and
rare and CP violating decays. After presenting the basic formalism for these
calculations we discuss in detail the effective hamiltonians for all decays for
which the next-to-leading corrections are known. Subsequently, we present the
phenomenological implications of these calculations. In particular we update
the values of various parameters and we incorporate new information on m_t in
view of the recent top quark discovery. One of the central issues in our review
are the theoretical uncertainties related to renormalization scale ambiguities
which are substantially reduced by including next-to-leading order corrections.
The impact of this theoretical improvement on the determination of the
Cabibbo-Kobayashi-Maskawa matrix is then illustrated in various cases.


title: Measurement of Dielectric Suppression of Bremsstrahlung

abstract:
  In 1953, Ter-Mikaelian predicted that the bremsstrahlung of low energy
photons in a medium is suppressed because of interactions between the produced
photon and the electrons in the medium. This suppression occurs because the
emission takes place over on a long distance scale, allowing for destructive
interference between different instantaneous photon emission amplitudes. We
present here measurements of bremsstrahlung cross sections of 200 keV to 20 MeV
photons produced by 8 and 25 GeV electrons in carbon and gold targets. Our data
shows that dielectric suppression occurs at the predicted level, reducing the
cross section up to 75 percent in our data.


title:
Dependence of Electromagnetic Form Factors of Hadrons on Light Cone
  Frames

abstract:
  A constituent quark model is developed for an arbitrary light- cone direction
\omega. Form factors are obtained from free one-body electromagnetic current
matrix elements. They are found to be \omega- independent for spin-0 mesons,
the nucleon and \Lambda hyperon, while there is \omega-dependence for spin-1
systems like the deuteron.


title:
Signals for Minimal Supergravity at the CERN Large Hadron Collider II:
  Multilepton Channels

abstract:
  We use ISAJET to perform a detailed study of the multilepton signals expected
from cascade decays of supersymmetric particle produced at the CERN LHC. Our
analysis is performed within the framework of the minimal supergravity model
with gauge coupling unification and radiative electroweak symmetry breaking. We
delineate the regions of parameter space where jets plus missing energy plus 1,
2 (opposite sign and same-sign dileptons), and 3 isolated lepton events should
be visible above standard model backgrounds. We find that if any $\eslt$ signal
at the LHC is to be attributed to gluino and/or squark production, and if
$m_{\tg} \alt 1$~TeV, then several of these signals must be simultaneously
observable. Furthermore, assuming $10\,\fb^{-1}$ of integrated luminosity, we
find that the reach for supersymmetry in the 1$\ell + \jets +\eslt$ channel
extends to $m_{\tg}\sim 2300\ (1600)$ GeV for $m_{\tq}\sim m_{\tg}$ ($m_{\tq}
\sim 1.5m_{\tg}$), and exceeds the corresponding reach in the $0\ell+\eslt$
channel. We show that measurements of the various topological cross sections,
jet and $B$-hadron multiplicities in these events, together with the charge
asymmetry for single lepton and same-sign dilepton events, and flavor asymmetry
for opposite sign dilepton events, serve to narrow the allowed range of
underlying SUGRA parameter values. We also delineate parameter regions where
signals with clean isolated dilepton (from slepton production) and trilepton
events (from chargino/neutralino production) are visible at the LHC, and
examine the extent to which these signals can be separated from other SUSY
sources.


title: Hadronic Correlation Functions in the Interacting Instanton Liquid

abstract:
  We study hadronic correlation functions in the interacting instanton liquid
model, both at zero and nonzero temperature $T$. At zero $T$ we investigate the
dependence of the correlators on the instanton ensemble, in particular the
effect of the fermionic determinant. We demonstrate that quark-induced
correlations between instantons are important, especially in the repulsive
$\eta'$ and $\delta$-meson channels. We also calculate a large number of
mesonic and baryonic correlation functions as a function of temperature. We
find three different types of behavior as $T\to T_c$. The vector channels
$\rho,a_1,\Delta$ show a gradual melting of the resonance contribution and
approach free quark behavior near the chiral phase transition. The light
pseudoscalars and scalars $\pi,\sigma$, as well as the nucleon show stable
resonance contributions, probably even surviving above $T_c$. Correlation
functions in the heavy scalar channels $\eta',\delta$ are enhanced as $T\to
T_c$.


title:
Dynamical Higgs Mechanism without Elementary Scalars: A Lesson from
  Instantons

abstract:
  The generation of gauge--dependent fermion vacuum condensates in Yang--Mills
theory would dynamically break the gauge symmetry and thus provide an
alternative to the Higgs mechanism in unified theories. We explore a simple
example: instanton-induced quark pair (diquark) condensation in QCD with 2
flavors and $N_c$ colors. We do find diquark condensates in the vacuum, but
only for $N_c = 2$, where they are equivalent to the standard quark-antiquark
condensate. At $N_c \geq 3$ diquark condensates exist as meta--stable saddle
points of the instanton-induced effective QCD action and may strongly affect
the properties of matter under extreme conditions. The scalar diquark
excitation, which is a Goldstone boson at $N_c =2$, becomes unbound for $N_c
\geq 3$.


title: On the importance of measuring $\rho$ at $\sqrt{s}>1$ TeV

abstract:
  We show that, even for a soft collision like forward elastic scattering, the
phase of the amplitude is extremely sensitive to a breakdown of strict
causality in local QFT. This is especially the case when the breakdown is
manifested by a failure of polynomial boundedness which leads to amplitudes
that in some complex direction have order 1 exponential growth in $|\sqrt{s}|$.


title: $W_R$ effects on $CP$ angles determination at a $B$ factory

abstract:
  The right-handed charged current gauge boson $W_R$ can affect significantly
on the determination of the $CP$ violation angles to be measured at $B$
factories if the right-handed current quark mixing matrix $V^R$ is taken to a
specific form to satisfy the bounds by neutral $K$ meson systems. The $W_R$
contribution can be sizable in $B^0$-$\overline{B^0}$ mixing and tree level $b$
quark decay. The deviation of $CP$ angles in unitarity triangle from the
standard model values can be as large as $-37^\circ$ or $ +22^\circ$ for
$\phi_3$ ($\gamma$), and $66^\circ \sim 115^\circ$ for $\phi_1$ ($\beta$) and
$\phi_2$ ($\alpha$).


title: Predictions From A U(2) Flavour Symmetry In Supersymmetric Theories

abstract:
  In a generic supersymmetric extension of the Standard Model, whether unified
or not, a simple and well motivated U(2) symmetry, acting on the lightest two
generations, completely solves the flavour changing problem and necessarily
leads to a predictive texture for the Yukawa couplings.


title: Realistic Quark and Lepton Masses through SO(10) Symmetry

abstract:
  In a recent paper a model of quark and lepton masses was proposed. Without
any family symmetries almost all the qualitative and quantitative features of
the quark and lepton masses and Kobayashi-Maskawa mixing angles are explained,
primarily as consequences of various aspects of $SO(10)$ symmetry. Here the
model is discussed in much greater detail. The threefold mass hierarchy as well
as the relations $m_\tau^0 \simeq m_b^0, ~m_\mu^0 \simeq 3m_s^0,~ m_e^0 \simeq
{1 \over 3} m_d^0, ~m_u^0/m_t^0 \ll m_d^0/m_b^0, ~{\rm tan}\theta_C \simeq
\sqrt{m_d^0/m_s^0},~ V_{cb} \ll \sqrt{m_s^0/m_b^0}$ and $V_{ub} \sim
V_{us}V_{cb}$ follow from a simple Yukawa structure at the unification scale.
The model also gives definite predictions for $\tan \beta$, the neutrino mixing
angles, and proton decay branching ratios. The $(\nu_\mu-\nu_\tau)$ mixing
angle is typically large, tan$\beta$ is close to either $m_t^0/m_b^0$ or
$m_c^0/m_s^0$, and proton decay is in the observable range, but there is a
group theoretical suppression factor in the rate.


title: A New Type of Resonant Neutrino Conversions Induced by Magnetic Fields

abstract:
  We consider resonant neutrino conversions in magnetised matter, such as a
degenerate electron gas. We show how magnetisation effects caused by axial
vector interactions of neutrinos with the charged leptons in the medium can
induce a new type of resonant neutrino conversion which may occur even in
situations where the MSW effect does not occur, such as the case of degenerate
or inverted neutrino mass spectra. Our new resonance may simultaneously affect
anti-neutrino $\bar{\nu_a} \leftrightarrow \bar{\nu}_b$ as well as neutrino
$\nu_{a} \leftrightarrow \nu_b$ flavour conversions, and therefore it may
substantially affect supernova neutrino energy spectra. Using SN1987A data we
conclude that only laboratory experiments with long baseline such as ICARUS or
MINOS are likely to find neutrino oscillations due to their sensitivity to
small $\Delta m^2$. We also comment on the possibility of resonant conversions
induced by Majorana neutrino transition moments and mention the case of sterile
neutrinos $\nu_s$.


title: E2 and C2 amplitudes for electroproduction of $\Delta$

abstract:
  We compute the amplitudes for the electromagnetic $\gamma_v N \to \Delta$
transition in the framework of soliton models with quarks and mesons. The
ratios E2/M1 and C2/M1 as functions of the photon four-momentum squared are
dominated by the contribution of the pion cloud and are in reasonable agreement
with the available experimental data.


title: Counting pions in the nucleon

abstract:
  The number of pions in the nucleon is a theoretical concept and its value is
model dependent. It is, however, a useful tool to understand the pionic
contribution to several nucleon observables such as electric charge radii,
magnetic moments, axial charge, pion-nucleon coupling constant, amplitudes for
electroexcitation of baryon resonances and electroproduction of pions above
such resonances.


title: Determination of polarized parton distributions in the nucleon

abstract:
  A fit to proton, neutron and deuteron spin asymmetries is presented and
polarized parton distributions in nucleon are given. These densities have their
roots in the MRS fit for unpolarized case. The integrals of polarized
distributions are compared with the experimental figures. The role of polarized
gluons is also discussed.


title: Evidence for mass dependent effects in the spin structure of baryons

abstract:
  We analyze the axial-vector form factors of the nucleon hyperon system in a
model with mass dependent quark spin polarizations. This mass dependence is
deduced from an earlier analysis\cite{jlhs,jlhs2} of magnetic moment data, and
implies that the spin contributions from the quarks to a baryon decrease with
the mass of the baryon. When applied to the axial-vector form factors, these
mass dependent spin polarizations bring the various sum-rules from the model in
better agreement with experimental data. Our analysis leads to a reduced value
for the total spin polarization of the proton.


title: Decays of b quark

abstract:
  Importance of studies of $b$ quark decays and experimental status of various
measurements are discussed.


title:
The Muon Anomalous Magnetic Dipole Moment in the Minimal Supersymmetric
  Standard Model

abstract:
  The muon anomalous magnetic dipole moment (MDM) is calculated in the
framework of the minimal supersymmetric standard model (MSSM). In this paper,
we discuss how the muon MDM depends on the parameters in MSSM in detail. We
show that the contribution of the superparticle-loop becomes significant
especially when $\tan\beta$ is large. Numerically, it becomes
$O(10^{-8}-10^{-9})$ in a wide parameter space, which is within the reach of
the new Brookhaven E821 experiment.


title: Wide-angle elastic scattering and color randomization

abstract:
  Baryon-baryon elastic scattering is considered in the independent scattering
(Landshoff) mechanism. It is suggested that for scattering at moderate
energies, direct and interchange quark channels contribute with equal color
coefficients because the quark color is randomized by soft gluon exchange
during the hadronization stage. With this assumption, it is shown that the
ratio of cross sections $R_{\overline{p} p/ p p}$ at CM angle $\theta = 90^0$
decreases from a high energy value of $R_{\pbar p / pp} \approx 1/2.7$, down to
$R_{\pbar p / pp} \approx 1/28$, compatible with experimental data at moderate
energies. This sizable fall in the ratio seems to be characteristic of the
Landshoff mechanism, in which changes at the quark level have a strong effect
precisely because the hadronic process occurs via multiple quark scatterings.
The effect of color randomization on the angular distribution of proton-proton
elastic scattering and the cross section ratio $R_{np/pp}$ is also discussed.


title: Intermediate scale as a source of lepton flavor violation in SUSY SO(10)

abstract:
  In supersymmetric SO(10) grand unified models, we examine the lepton flavor
violation process $\mu \rightarrow e\gamma$ from having the SU(2)$_R\times
$U(1)$_{B-L}$ gauge symmetry broken at an intermediate scale $M_I$ below the
SO(10) grand unification scale $M_G$. Even in the case that supersymmetry is
broken by universal soft terms introduced at the scale $M_G$, we find
significant rates for $\mu\rightarrow e\gamma$ with $M_I \sim 10^{12}$ GeV or
less. These rates are further enhanced if the universal soft terms appear at a
scale greater than $M_G$.


title: $(S_3)^3$ flavor symmetry and $p\to K^0 e^+$

abstract:
  We show how to incorporate the lepton sector in a supersymmetric theory of
flavor based on the discrete flavor group $(S_3)^3$. Assuming that all possible
nonrenormalizable operators are generated at the Planck scale, we show that the
transformation properties of the leptons and of the flavor-symmetry breaking
fields are uniquely determined. We then demonstrate that the model has a viable
phenomenology and makes one very striking prediction: the nucleon decays
predominantly to $K l$ where $l$ is a {\em first} generation lepton. We show
that the modes $n \rightarrow K^0 \bar{\nu}_e$, $p\rightarrow K^+ \bar{\nu}_e$,
and $p\rightarrow K^0 e^+$ occur at comparable rates, and could well be
discovered simultaneously at the SuperKamiokande experiment.


title: Top Quark Mass Predictions from Gauge-Yukawa Unification

abstract:
  Gauge-Yukawa Unification (GYU) is a renormalization group invariant
functional relation among gauge and Yukawa couplings which holds beyond the
unification point in Grand Unified Theories (GUTs). Here, GYU is obtained by
requiring finiteness and reduction of couplings to all orders in perturbation
theory. We examine the consequences of GYU in various supersymmetric GUTs and
in particular the predictions for the top quark mass. These predictions are
such that they distinguish already GYU from ordinary GUTs. Moreover, when more
accurate measurements of the top quark mass are available, it is expected that
it will be possible to discriminate among the various GYUs.


title: Vacuum decay along supersymmetric flat directions

abstract:
  It has been recently realized that within the Minimal Supersymmetric Standard
Model, for certain patterns of superpartner masses, consistent with all the
present experimental constraints, the scalar potential may develop at some
scale $Q_0$ unbounded color/charge breaking directions involving the sfermion
fields, and that these patterns are then excluded unless some new physics is
invoked at or below the scale $Q_0$. We reanalyze this observation and point
out that such patterns of superpartner masses at the weak scale are {\it not}
ruled out when taking into account the probability of decay for the metastable
color conserving minimum along these color breaking unbounded directions. It
turns out that the color conserving minimum, although metastable, has a
lifetime longer than the present age of the Universe and can survive both
quantum tunneling and the effects of high temperatures in the early Universe,
causing the color/charge breaking effects to be in practice not dangerous.


title:
Hadronic Component of the Photon Spin Dependent Structure Function
  $g_1^{\gamma}$ from QCD

abstract:
  We calculate the spin dependent structure function of the polarized virtual
photon $g_1^{\gamma}(x,Q^2,p^2)$, especially its hadronic part, using the OPE
in the inverse powers of the target photon virtuality. Some model is accepted
to achieve a correct analytical behaviour in the photon squared mass. This
enables extrapolation to the case of a real photon.


title: Degenerate BESS at future $e^+e^-$ colliders

abstract:
  An effective lagrangian describing a strong interacting electroweak sector is
considered. It contains new vector and axial-vector resonances all degenerate
in mass and mixed with $W$ and $Z$. The model, for large mass of these
degenerate gauge bosons, becomes identical to the standard model in the limit
of infinite Higgs mass. The limits on the parameter space of this model from
future $e^+e^-$ colliders are presented.


title: Determination of Two-Loop $\pi\pi$ Scattering Amplitude Parameters

abstract:
  The chiral expansion of the $\pi\pi$ amplitude to the order of two loops was
expressed in terms of six independent parameters in a previous paper: four of
these are shown here to satisfy sum rules. Their derivation, where crossing
symmetry plays a key role, is explained. Their convergence properties are
studied and their practical evaluation, in terms of the available data on
$\pi\pi$ phase shifts above 0.5 GeV, is discussed. Below 0.5 GeV, the chiral
amplitude itself is employed, such that the parameters are determined in a
self-consistent way. Some care is devoted to the estimate of the errors.


title:
A simple recipe to detect possible C-Odd effects in high energy $\bar p
  p$ and $pp$

abstract:
  We provide a theorem to suggest that $t=0$ data may already be sufficient to
detect possible asymptotic C-odd (Odderon) contributions. This can be done by
comparing $\bar p p$ and $pp$ $t=0$ observables such as total cross sections,
forward angular distributions and ratios of real to imaginary forward
amplitudes for which well defined model independent correlations {must} exist
which could already show up at RHIC energy but definitely at LHC energies.


title: Polarized Parton Distributions in the Nucleon

abstract:
  The distribution of the spin of the nucleon among its constituents can be
parametrized in the form of polarized parton distribution functions for quarks
and gluons. Using all available data on the polarized structure function
$g_1(x,Q^2)$, we determine these distributions both at leading and
next-to-leading order in perturbation theory. We suggest three different,
equally possible scenarios for the polarized gluon distribution, which is found
to be only loosely constrained by current experimental data. We examine various
possibilities of measuring polarized parton distributions at future
experiments.


title: Are IR Renormalons a Good Probe for the Strong Interaction Domain?

abstract:
  We study the origin of non-analyticity in \alpha_s of a short-distance QCD
observable to demonstrate that the infrared renormalons, the same-sign
factorial growth of the perturbative expansion, is a universal phenomenon that
originates entirely from the small coupling domain. In particular, both the
position and the nature of the singularity of the Borel transform of the
perturbative series prove to be independent of whether the running coupling
\alpha(k^2) becomes singular at some finite scale ("Landau pole"), or stays
finite down to k^2=0. We argue that getting hold of the infrared renormalons
per se can help next to nothing in quantifying non-perturbative effects.


title:
Standard Model Higgs boson production and hard photon radiation in
  $e^+e^-\to \mu^+\mu^- b\bar b\gamma $ events at LEP II and Next Linear
  Collider

abstract:
  We study at LEP II and Next Linear Collider energies Higgs production via the
bremsstrahlung channel $e^+e^-\ar ZH$, with $Z\ar \mu^+\mu^-$ and $H\ar b\bar
b$, and the corresponding irreducible background, in presence of hard photon
radiation, both from the initial and the final state. We carry out an analysis
that includes the computation of all the relevant contributions to the complete
tree--level matrix element for $e^+e^-\ar \mu^+\mu^- b\bar b\gamma $ and makes
use of the one at leading order $e^+e^-\ar \mu^+\mu^- b\bar b$ interfaced with
electron structure functions. We concentrate on the case of mass degeneracy
$M_H\approx M_Z$, for which next--to--leading electromagnetic contributions can
modify the content of $b\bar b$--pairs coming from $H$ and $Z$ decays. A brief
discussion concerning the case $M_H\not\approx M_Z$ is also given.


title: Polarized Top Quarks

abstract:
  Recent calculations are presented of top quark polarization in $t\bar t$ pair
production close to threshold. S-P-wave interference gives contributions to all
components of the top quark polarization vector. Rescattering of the decay
products is considered. Moments of the fourmomentum of the charged lepton in
semileptonic top decays are calculated and shown to be very sensitive to the
top quark polarization.


title:
The Gluon Distribution as a Function of F$_2$ and dF$_2$/dlnQ$^2$ at
  small x. The Next-to-Leading Analysis

abstract:
  We present a set of formulae to extract the gluon distribution function from
the deep inelastic structure function F$_2$ and its derivative dF$_2$/dlnQ$^2$
at small x in the leading and next-to-leading order of perturbation theory. The
detailed analysis is given for new HERA data. The values of the gluon
distribution are found in the range $10^{-4} \leq x \leq 10^{-2}$ at $Q^2=20$
GeV$^2$.


title:
Gluino and Neutralino contribution to the direct CP violating parameter
  epsilon'

abstract:
  I present a detailed and complete calculation of the gluino and neutralino
contribution to the direct CP violating parameter $\epsilon'$\ within the MSSM.
I include the complete mixing matrices of the neutralinos and of the scalar
partners of the left and right handed down quarks. I find that the neutralino
contribution is generally small but can be larger than the gluino contribution
for small values $m_S\le 400$\ GeV of the supersymmetric breaking scale.


title: Towards Yukawa unification in a strongly Yukawa coupling model

abstract:
  For strong enough Yukawa coupling the electroweak standard model fermion
finds it energetically advantageous to transform itself into a bound state in
the hedgehog background of Higgs field in semiclassical approximation. By
considering the bound states give the masses for lepton and quark, we found
that all the strongly Yukawa coupling constants tend to an unitary constant. On
the other hand, the masses of $W$ and $Z$ produced by the hedgehog Higgs field
keep almost no change.


title: The decays $K \to \pi \pi \nu \overline\nu$ within the standard model

abstract:
  We study the reactions $K \rightarrow \pi \pi \nu \overline{\nu}$ within the
minimal standard model. We use isospin symmetry to relate the matrix elements
to the form factors measured in $K_{\ell 4}$. We argue that these modes are
short distance dominated and can be used for precise determinations of the CKM
parameters $\rho$ and $\eta$. Depending on the value of the CKM angles we find
branching ratios in the following ranges: $B(K_L \rightarrow \pi^+ \pi^- \nu
\overline{\nu}) = [2-5] \times 10^{-13}$; $B(K_L \rightarrow \pi^0 \pi^0 \nu
\overline{\nu}) = [1-3] \times 10^{-13}$; $B(K^+ \rightarrow \pi^+ \pi^0 \nu
\overline{\nu}) = [1-2] \times 10^{-14}$. We also discuss a possible $CP$-odd
observable.


title:
Form Factors for Semi-Leptonic and Radiative Decays of Heavy Mesons to
  Light Mesons

abstract:
  To know and understand form factors of hadronic currents is of decisive
importance for analysing exclusive weak decays. The ratios of different form
factors of a given process depend on the relativistic spin structure of initial
and final particles. It is shown --- assuming simple properties of the
spectator particle --- that these ratios can entirely be expresssed in terms of
particle and quark mass parameters. For quark masses large compared to the
spectator mass the Isgur-Wise relations follow. The corresponding amplitudes
for heavy-to-light transitions show a very similar structure. In particular,
the $F_0$ and $A_1$ form factors behave again differently from the $F_1, A_2,
V$ and $T_1$ form factors.


title: Hierarchies and Textures in Supergravity Unification

abstract:
  It is proposed that supergravity unified models contain in addition to the
hidden and the visible sectors, a third sector which contains exotic matter
with couplings to the fields of both the visible and the hidden sectors. After
spontaneous breaking of supersymmetry exotic matter becomes superheavy and its
elimination leads to quark-lepton textures at the GUT scale with a hierarchy in
powers of $M_G/M_P$.Textures in the Higgs triplet sector are also computed and
it is shown that they modify predictions of proton decay in unified models.


title: Supersymmetric Dark Matter

abstract:
  A review of supersymmetric dark matter in minimal supergravity unification
with R-parity invariance and with radiative breaking of the electro-weak
symmetry is given. The analysis shows the lightest neutralino is the LSP over
most of the parameter space of the supergravity model. The event rates in
neutralino- nucleus scattering in dark matter detectors are also discussed.It
is found that the event rates are sensititive to the constraint from the
$b\rightarrow s\gamma$ experiment.It is also found that the event rates are
sensitive to the constraints of relic density and in our analysis we have used
the accurate method for the computation of the neutralino relic density.
Finally,the effect of the new results on quark polarizabilities, from the data
of the Spin Muon Collaboration, on event rates is also discussed.The analysis
shows that the event rates for the Ge detectors and for other detectors which
use heavy targets are only negligibly affected.


title: On the Observation of Top Spin Correlation Effect at Tevatron

abstract:
  We propose to observe the top spin correlation effect at Tevatron through the
measurement of the correlated asymmetries of the charged lepton momenta using
the dilepton decay events of top and anti-top quark pairs. The possibility of
reconstructing the events and observing the asymmetries at 3$\sigma$ level with
projected luminosity of the Tevatron for Run II is demonstrated by simulation.
The effect can provide the first direct measurement of the spin of a quark.


title: On asymmetry in inclusive pion production

abstract:
  On the basis of the mechanism proposed for one-spin asymmetries in inclusive
hadron production we specify an $x$--dependence of asymmetries in inclusive
processes of pion production. The main role in generation of this asymmetry
belongs to the orbital angular momentum ofquark-antiquark cloud in internal
structure of constituent quarks. The $x$--dependence of asymmetries in the
charged pion production at large $x$ reflects the corresponding dependence of
constituent quark polarization in the polarized proton.


title: Review of Selected Topics in HQET

abstract:
  A few topics on the expansion in heavy quark mass are discussed. The
theoretical framework is the Wilson Operator Product Expansion rather than the
Heavy Quark Effective Theory.


title: Nobel Leptons

abstract:
  The 1995 Nobel Prize in Physics is shared equally by the American physicists
Frederick J. Reines and Martin L. Perl for their pioneering experimental
contributions to lepton physics. Following is a brief account of their
discoveries.


title:
Spontaneous CP Violation and Higgs Masses in the Next-to-Minimal
  Supersymmetric Model

abstract:
  We study the possibility of spontaneous CP violation in the next-to-minimal
supersymmetric standard model (NMSSM). It is shown that the spontaneous CP
violation is induced by the radiative effects of top, stop, bottom and sbottom
superfields. The available regions of parameters, which are obtained by
imposing the constraints from experiments, are rather narrow. We also obtain
strong constraints for light Higgs masses such as m_H \le 36 GeV numerically.
Sum of masses of two light neutral Higgs should set around 93 GeV and charged
Higgs boson has a rather higher mass larger than 700 GeV.


title: Triviality Bound on Lightest Higgs Mass in NMSSM

abstract:
  We study the implication of triviality on Higgs sector in next to minimal
supersymmetric model (NMSSM) using variational field theory. It is shown that
mass of the lightest Higgs boson in NMSSM has an upper bound $\sim 10\, M_W$
which is of the same order as that in standard model.


title: Constraining the Right Handed Interactions from Pion Condensate Matter

abstract:
  We consider right handed neutrino emission from charged and neutral pion
condensate matter likely to be present in the supernova core associated with SN
1987 A. This is used to constrain the strength of right handed interaction and
we get excluded range of values for the right handed $W$ boson and extra
neutral $Z'$ boson masses. For vanishing $W_L-W_R$ mixing we obtain $
(1.3-1.8)\,M_{W_L} \,\approx \leq\,M_{W_R} \, \leq\approx 100\, M_{W_L} \, {\rm
and}\, (1.3-1.8)\,M_{W_L}\, \approx \leq \, M_{N'}\,\leq\approx \,225
\,M_{W_L}$


title: $\gamma$ - Z interferometry at a $\Phi$-factory

abstract:
  We analyze the possibilities that the proposed $\Phi$-factories offer to
measure $\gamma-Z$ interference. In the unpolarized beam case, we study
different signatures in the $\rho \pi$ channel, taking advantage of the
presence of the near-by $a_1$ resonance. We build a C-odd forward-backward
asymmetry, estimated to be around $10^{-5}$, and (P-even, T-even) and (P-odd,
T-odd) alignments of the $\rho$, to be seen from the angular distribution of
its $\pi \pi$ decay products. With polarized electrons a left-right asymmetry
around $2\times 10^{-4}$ is present in all channels. At leading order this
asymmetry is independent of hadronic matrix elements and is sensitive to the
$Z^0-s\bar{s}$ vector coupling. In the $\rho \pi$ channel, a combined
left-right forward-backward asymmetry is considered.


title: Implications of Precision Electroweak Data

abstract:
  There are two aspects to the 1995 summer update of the combined preliminary
electroweak data from LEP and SLC. On the one hand, agreement between
experiments and the Standard Model (SM) has improved for the line-shape and the
asymmetry data. The $\tau$ widths and asymmetries are now consistent with
$e$--$\mu$--$\tau$ universality, and all the asymmetry data including the
left-right asymmetry from SLC are consistent with the SM (16\%CL). On the other
hand, a discrepancy between experiments and SM predictions is sharpened for two
observables, $R_b$ and $R_c$, where $R_q$ is the partial $Z$ boson width ratio
$\Gamma_q/\Gamma_h$. $R_b$ is 3\% larger (3.7$\sigma$) and $R_c$ is 11\%
smaller (2.5$\sigma$) than the SM predictions. When combined, the SM is ruled
out at the 99.99\%CL for $m_t>170$GeV. It is difficult to interpret the $11\pm
4$\% deficit of $R_c$, since if we allow only $\Gamma_b$ and $\Gamma_c$ to
deviate from the SM then the precisely measured ratio
$R_h=\Gamma_h/\Gamma_\ell$ forces the QCD coupling to be $\alpha_s\equiv
\alpha_s(m_Z)_{\overline{\rm MS}}=0.185\pm 0.041$, which is uncomfortably
large. The data can be consistent with the prefered $\alpha_s$
($0.10<\alpha_s<0.13$) only if the sum $\Gamma_h=\Sigma_q \Gamma_q$ does not
deviate significantly from the SM prediction. Possible experimental causes for
the under-estimation of $R_c$ are discussed. By assuming the SM value for
$R_c$, the discrepancy in $R_b$ decreases to 2\% (3$\sigma$). The double
tagging technique used for the $R_b$ measurements is critically reviewed. A few
theoretical models that can explain large $R_b$ and small $\alpha_s$ ($=
0.104\pm 0.008$) are discussed. If the QCD coupling $\alpha_s$ is allowed to be
fitted by the data, the standard $S$, $T$, $U$ analysis for a new physics


title:
Missing Doublet Multiplet as the Origin of the Doublet-Triplet Splitting
  in SUSY SU(6)

abstract:
  In a $SU(6)$ gauge theory we found the irreducible representation (175-plet)
which does not contain the Higgs doublet. Using this representation we
construct two SUSY $SU(6)$ models in which the doublet-triplet splitting occurs
naturally, without fine tuning. The crucial role is played by the ``custodial"
global $SU(2)_H$ in combination with discrete or continuous $R$ symmetries.


title: Hard Diffraction in the QCD Dipole Picture

abstract:
  Using the QCD dipole picture of the BFKL pomeron, the gluon contribution to
the cross-section for single diffractive dissociation in deep-inelastic
high-energy scattering is calculated. The resulting contribution to the proton
diffractive structure function integrated over $t$ is given in terms of
relevant variables, $x_{\cal P}, Q^2, $ and $\beta = x_{Bj}/x_{\cal P}.$ It
factorizes into an explicit $x_{\cal P}-$dependent Hard Pomeron flux factor and
structure function. The flux factor is found to have substantial logarithmic
corrections which may account for the recent measurements of the Pomeron
intercept in this process. The triple Pomeron coupling is shown to be strongly
enhanced by the resummation of leading logs. The obtained pattern of scaling
violation at small $\beta$ is similar to that for $F_2$ at small $x_{Bj}.$


title: Chirality-preserving neutrino oscillations in an external magnetic field

abstract:
  Neutrinos propagating in matter acquire an effective electromagnetic vertex
induced by their weak interactions with the charged particles in the
background. In the presence of an external magnetic field the induced vertex
affects the flavor transformations of mixed neutrinos in a way that, in
contrast to the oscillations driven by an intrinsic magnetic moment
interaction, preserve chirality. We derive the evolution equation for this case
and discuss some of the physical consequences in environments such as a
supernova. For small values of the square mass difference the resonance for
neutrinos and antineutrinos occur within regions which are close. In that case,
the resonance condition becomes independent of the vacuum parameters and is
approximately the same for both.


title:
The Fermion Generations Problem in the Gust in the Free World-Sheet
  Fermion Formulation

abstract:
  In the framework of the four dimensional heterotic superstring with free
fermions we present a revised version of the rank eight Grand Unified String
Theories (GUST) which contain the $SU(3)_H$-gauge family symmetry. We also
develop some methods for building of corresponding string models. We explicitly
construct GUST with gauge symmetry $ G = SU(5) \times U(1)\times (SU(3) \times
U(1))_H$ and $G = SO(10)\times (SU(3) \times U(1))_H $ or $E(6)\times SU(3)_H$
$\subset E(8)$ and consider the full massless spectrum for our string models.
We consider for the observable gauge symmetry the diagonal subgroup $G^{symm}$
of the rank 16 group $G \times G$ $\subset SO(16) \times SO(16)$ or $\subset
E(8) \times E(8)$. We discuss the possible fermion matter and Higgs sectors in
these theories. We study renormalizable and nonrenormolizable contributions to
the superpotential. There has to exist "superweak" light chiral matter ($m_H^f
< M_W$) in GUST under consideration. The understanding of quark and lepton mass
spectra and family mixing leaves a possibility for the existence of an
unusually low mass breaking scale of the $SU(3)_H$ family gauge symmetry (some
TeV).


title: Implications of Anomaly Constraints in the $N_c$-Extended Standard Model

abstract:
  We discuss some implications of anomaly cancellation in the standard model
with (i) the color group extended to $SU(N_c)$, and (ii) the leptonic sector
extended to allow right-handed components for neutrinos.


title: Phenomenological constraints on a scale-dependent gravitational coupling

abstract:
  We investigate the astrophysical and cosmological implications of the
recently proposed idea of a running gravitational coupling on macroscopic
scales. We find that when applied to the rotation curves of galaxies, their
flatness requires still the presence of dark matter. Bounds on the variation of
the gravitational coupling from primordial nucleosynthesis, change of the
period of binary pulsars, gravitational lensing and the cosmic virial theorem
are analysed.


title: Integral Transform Technique for Meson Wave Functions

abstract:
  In a recent paper [1] we have proposed a new approach for extracting the wave
function of the $\pi$-meson $\varphi_{\pi}(x)$ and the masses and
  wave functions of its first resonances from the new QCD sum rules for
non-diagonal correlators obtained in [2]. Here, we test our approach using an
exactly solvable toy model as an illustrating example. We demonstrate the
validity of the method and suggest a pure algebraic procedure for extracting
the masses and wave functions relating to the case under investigation. We also
explore the stability of the procedure under perturbations of the theoretical
part of the sum rule. In application to the pion case, this results not only in
the mass and wave function of the first resonance ($\pi'$), but also in the
estimation of $\pi''$-mass.


title: Power Corrections in QCD: A Matter of Energy Resolution

abstract:
  We consider power-like corrections in QCD which can be viewed as power
surpressed infrared singularities. We argue that the presence of these
singularities depends crucially on the energy resolution. In case of poor
energy resolution, i.e., inclusive cross sections, there are constraints on
infrared singularities expressed by the Kinoshita-Lee-Nauenberg (KLN) theorem.
We rewrite the theorem in covariant notations and argue that the KLN theorem
implies the extension of the Bloch-Nordsieck cancellation of logarithmic
singularities to the case of linear corrections.


title:
Gauge-independent Thermal $\beta$ Function In Yang-Mills Theory via the
  Pinch Technique

abstract:
  It is proposed to use the pinch technique (PT) to obtain the
gauge-independent thermal $\beta$ function $\beta_T$ in a hot Yang-Mills gas.
Calculations of the thermal $\beta$ function are performed at one-loop level in
four different gauges, (i) the background field method with an arbitrary gauge
parameter, (ii) the Feynman gauge, (iii) the Coulomb gauge, and (iv) the
temporal axial gauge. When the pinch contributions to the gluon self-energy are
included, the same result is derived for $\beta_T$ in all four cases.


title: Testing Gauge-Yukawa-Unified Models By $M_t$

abstract:
  Gauge-Yukawa Unification (GYU) relates the gauge and Yukawa couplings,
thereby going beyond the usual GUTs, and it is assumed that the GYU in the
third fermion generation implies that its Yukawa couplings are of the same
order as the unified gauge coupling at the GUT scale. We re-examine carefully
the recent observation that the top-bottom mass hierarchy can be explained to a
certain extent in supersymmetric GYU models. It is found that there are
equiv-top-mass-lines in the boundary conditions of the Yukawa couplings so that
two different GYU models on the same line can not be distinguished by the top
mass $M_t$ alone. If they are on different lines, they could be distinguished
by $M_t$ in principle, provided that the predicted $M_t$'s are well below the
infrared value $M_t$ (IR). We find that the ratio $M_t ({\rm IR})/\sin\beta$
depends on $\tan\beta$ for large $\tan\beta$ and the lowest value of $M_t ({\rm
IR})$ is $\sim 188$ GeV. We focus our attention on the existing $SU(5)$ GYU
models which are obtained by requiring finiteness and reduction of couplings.
They, respectively, predict $M_t= (183+\delta^{\rm MSSM} M_t\pm 5)$ GeV and
$(181+\delta^{\rm MSSM} M_t\pm 3)$ GeV, where $\delta^{\rm MSSM} M_t$ stands
for the MSSM threshold correction and is $\sim -2$ GeV for the case that all
the MSSM superpartners have the same mass $M_{\rm SUSY}$ with $\mu_H/M_{\rm
SUSY} <<1$.


title: Leptons and Photons

abstract:
  It is assumed that three lepton families $(\nu_e, e)$, $(\nu_{\mu}, \mu)$,
$(\nu_{\tau}, \tau)$ carry charges, which are sources of electronic, muonic and
tauonic massless vector particles, respectively. Various manifestations of
these hypothetical photons are discussed.


title: MSSM radiative contributions to the WW$\gamma$ and WWZ form factors

abstract:
  We evaluate one-loop contributions to the C and P conserving $WW\gamma, WWZ$
form factors in the Minimal Supersymmetric Standard Model (MSSM), and in a more
constrained Supergravity Grand Unified Theory (SUGRA-GUT). A systematic search
of maximal effects in the available parameter space, shows that at LEP2 energy
MSSM contributions can hardly reach the border of the most optimistic accuracy
expected on those couplings, even for particles close to their production
thresholds. At NLC energies, the effects are more comfortably of the order of
the expected sensitivity, and may therefore provide useful information on MSSM
parameter values which will not be available from direct particle production.
We also discuss briefly some variance with other studies.


title: Rb and Rc Crises

abstract:
  The Rb and Rc crises described by Kaoru Hagiwara in hep-ph/9512425 can be
resolved by the T-quark mass value of 130 GeV and the alpha_s(M_Z) value of
0.106 of the D4-D5-E6 model described in hep-ph/9501252 and quant-ph/9503009.


title:
Supernatural Inflation: Inflation from Supersymmetry with No (Very)
  Small Parameters

abstract:
  Most models of inflation have small parameters, either to guarantee
sufficient inflation or the correct magnitude of the density perturbations. In
this paper we show that, in supersymmetric theories with weak scale
supersymmetry breaking, one can construct viable inflationary models in which
the requisite parameters appear naturally in the form of the ratio of mass
scales that are already present in the theory. Successful inflationary models
can be constructed from the flat-direction fields of a renormalizable
supersymmetric potential, and such models can be realized even in the context
of a simple GUT extension of the MSSM. We evade naive ``naturalness" arguments
by allowing for more than one field to be relevant to inflation, as in ``hybrid
inflation" models, and we argue that this is the most natural possibility if
inflaton fields are to be associated with flat direction fields of a
supersymmetric theory. Such models predict a very low Hubble constant during
inflation, of order $10^3$-$10^4$ GeV, a scalar density perturbation index $n$
which is very close to or greater than unity, and negligible tensor
perturbations. In addition, these models lead to a large spike in the density
perturbation spectrum at short wavelengths.


title:
In Search of the Quark Spins in the Nucleon: A Next--to--Next--to--
  Leading Order QCD Analysis

abstract:
  The data from the last seven experiments performed on polarized
deep--inelastic scattering on proton and neutron (or deuteron) targets have
been analyzed in search of a precise determination of the spin fraction carried
by the quarks in the nucleon. We find that this fraction can be of the size
expected from na\"{\i}ve quark model arguments, provided the gluon axial
anomaly is explicitly included and the isosinglet axial charge normalization is
fixed at a suitably low momentum scale, such that a) the running, strong
coupling constant is about unit, and b) the orbital angular momentum inside the
nucleon vanishes.
  We also find that, despite the appeal of this solution of the ``nucleon spin
crisis'', a solution where the axial anomaly is absent and its effects are
traded for an appreciable strange quark polarization can not however be
excluded --- because of the limited accuracy of the data --- unless this latter
and/or the gluon polarization in the nucleon are explicitly measured.


title:
Production of neutral MSSM Higgs bosons in $e^+e^-$ collisions: a
  complete 1-loop calculation

abstract:
  We present the first complete 1-loop diagrammatic calculation of the cross
sections for the neutral Higgs production processes $e^+e^-\ra Z^0h^0$ and
$e^+e^-\ra A^0h^0$ in the minimal supersymmetric standard model. We compare the
results from the diagrammatic calculation with the corresponding ones of the
simpler and compact effective potential approximation and discuss the typical
size of the differences.


title:
Recurrence Relations for Three-Loop Prototypes of Bubble Diagrams with a
  Mass

abstract:
  Recurrence relations derived via the Chetyrkin--Tkachov method of integration
by parts are applied to reduce scalar three-loop bubble (vacuum) diagrams with
a mass to a limited number of master integrals. The reduction is implemented as
a package of computer programs for analytic evaluation in FORM. The algorithms
are applicable to diagrams with any integer powers on the lines in an arbitrary
dimension. A physical application is the evaluation of the three-loop QCD
correction to the electroweak rho parameter.


title: Chirality in the Early Universe

abstract:
  The early big bang is an alphabet soup of quarks, W bosons, gluons, and other
exotic particles and flavors. In the usual scenario, there is no place for the
pion. It dissociates in the alphabet soup of the early universe. I will show
that this scenario is naive. The thermal vacuum is a far more complex state,
and the pion remains a Nambu-Goldstone particle at high $T$, and will not
dissociate. It propagates at the speed of light but {\em with a halo}.


title:
A prediction for three neutrino masses and mixings and similarity
  between quark and lepton mixings

abstract:
  If neutrinos have mass, we give reasons for a possible pattern of three
(squared) mass eigenvalues: $m_1^2 \simeq (2.8 - 5.8) \, \mbox{(eV)}^2 $,
$m_2^2 \simeq 0.01 \, \mbox{(eV)}^2 $, $m_3^2 \simeq (1.5 - 1) \times 10^{-4}
\mbox{(eV)}^2 $. The flavor states $\nu_{\mu} $ and $\nu_e $ are mixtures of
the eigen\-states with $m_2 $ and $m_3 $ with a significant mixing,
corresponding to an effective mixing angle of about 0.45. The $\nu_{\tau} $ is
nearly the state with $m_1 $; the other two effective mixing angles are about
an order of magnitude smaller than 0.45. There is a marked similarity to mixing
in the quark sector.


title: R(b), R(c) and New Physics: An Updated Model Independent Analysis

abstract:
  We analyze LEP and SLC data from the 1995 Summer Conferences as well as from
low energy neutral current experiments for signals of new physics. The reasons
for doing this are twofold, first to explain the deviations from the standard
model observed in $R_b$ and $R_c$ and second to constrain non-standard
contributions to couplings of the $Z^0$ boson to all fermions and to the
oblique parameters. We do so by comparing the data with the Standard Model as
well as with a number of test hypotheses concerning the nature of the new
physics. These include non-standard $Zb\bar{b}$-, $Zc\bar{c}$- and
$Zs\bar{s}$-couplings as well as the couplings of the $Z^0$ to fermions of the
entire first, second and third generations and universal corrections to all up-
and down-type quark couplings (as can arise \eg\ in $Z'$ mixing models). We
find that non-standard $Zb\bar{b}$ couplings are both necessary and sufficient
to explain the data and in particular the $R_b$ anomaly. It is not possible to
explain $R_b$, $R_c$ and a value of the strong coupling constant consistent
with low energy determinations invoking only non-standard $Zb\bar{b}$- and
$Zc\bar{c}$-couplings. To do so one has to have also new physics contributions
to the $Zs\bar{s}$ or universal corrections to all $Zq\bar{q}$ couplings.


title: Four-Generation Low Energy Supersymmetry with a Light Top Quark

abstract:
  A supersymmetric model with four generations is proposed, in which the top
quark is approximately degenerate in mass with the $W^{\pm}$ gauge boson,
$m_t\simeq m_W$, leading to values of $R_b$ in better agreement with the
present experimental data than in the Standard Model. The model shares many of
the good features of the minimal supersymmetric extension of the Standard Model
(MSSM), such as the unification of gauge and Yukawa couplings at a common
high-energy scale. The model differs from the MSSM by re-interpreting the
Tevatron ``top-quark'' events as the production of the fourth generation quark
$t\pri$, which decays dominantly to $bW^+$. The top quark decays primarily into
supersymmetric particles, $t\rta\widetilde t\widetilde\chi^0_1$, with
$\widetilde t\rta c\widetilde\chi^0_1$, thereby evading previous searches.
Light supersymmetric particles are predicted to lie in the mass range between
25 and 70 GeV, which together with the fourth generation leptons provide a rich
spectrum of new physics which can be probed at LEP-2 and the Tevatron.


title: Diffractive Production of Vector Mesons at Large t

abstract:
  The cross section for elastic vector meson production in photon-proton
interactions at large $t$ is considered using the exact analytic solution of
the BFKL equation in the azimuthally symmetric $n=0$ limit. We use a
non-relativistic model for the vector meson production and find a small
shrinkage in the $t$-distribution with increasing energy.


title: Flavourdynamics

abstract:
  These lectures provide an introductory overview of the dynamics of
flavour-changing transitions. The main emphasis is put on present tests of the
quark-mixing matrix structure and the phenomenological determination of its
parameters. The interplay of strong interactions in weak decays and the
important role of flavour symmetries for controlling the size of QCD
corrections to some semileptonic transitions are discussed.


title: $SU(5)\times SU(5)$ Unification, Seesaw Mechanism and R-Conservation

abstract:
  A new supersymmetric grand unified model based on the gauge group
$SU(5)\times SU(5)$ is discussed. The model has the feature that the
conventional seesaw mechanism for neutrino masses is implemented using the
$(15, 1)+(1,\bar{15)}$ representation. This multiplet may have a better chance
of arising from level two compactification of superstring theories than the the
${bf \bar{126}}$ representation used in the SO(10) model. The model also
naturally suppresses all R-parity violating interactions.


title: B decays and models for CP violation

abstract:
  The decay modes $B$ to $\pi\pi$, $\psi K_S$, $K^- D$, $\pi K$ and $\eta K$
are promising channels to study the unitarity triangle of the CP violating CKM
matrix. In this paper I study the consequences of these measurements in the
Weinberg model. I show that using the same set of measurements, the following
different mechanisms for CP violation can be distinguished: 1) CP is violated
in the CKM sector only; 2) CP is violated spontaneously in the Higgs sector
only; And 3) CP is violated in both the CKM and Higgs sectors.


title: Lifetime of quasiparticles in hot QED plasmas

abstract:
  The calculation of the lifetime of quasiparticles in a QED plasma at high
temperature remains plagued with infrared divergences, even after one has taken
into account the screening corrections. The physical processes responsible for
these divergences are the collisions involving the exchange of very soft,
unscreened, magnetic photons, whose contribution is enhanced by the thermal
Bose-Einstein occupation factor. The self energy diagrams which diverge in
perturbation theory contain no internal fermion loops, but an arbitrary number
of internal magnetostatic photon lines. By generalizing the Bloch-Nordsieck
model at finite temperature, we can resum all the singular contributions of
such diagrams, and obtain the correct long time behaviour of the retarded
fermion propagator in the hot QED plasma: $S_R(t)\sim \exp\{-\alpha T \, t\,
\ln\omega_pt\}$, where $\omega_p=eT/3$ is the plasma frequency and
$\alpha=e^2/4\pi$.


title: Two-Photon Decays of Mesons in a Relativistic Quark Model

abstract:
  We present a relativistic calculation of two-photon decays for heavy and
light mesons in the framework of the Salpeter equation for quark-antiquark
states. The meson-photon-photon vertex is computed by reconstructing the
Bethe-Salpeter vertex function and evaluating the four-dimensional Feynman
diagram with off-shell quark amplitudes. The two-photon width for light and
heavy quarkonia up to spin equal six are calculated with different parameter
sets taken from the literature thus giving a complete overview on the mesonic
two-photon physics. We find that relativistic effects including the negative
energy components of the wave function are important for any two-photon width -
even for heavy quarkonia - yielding a remarkable agreement with available data.


title: Relativistic SU(4) and Quaternions

abstract:
  A classification of hadrons and their interactions at low energies according
to SU(4) allows to identify combinations of the fifteen mesons $\pi$, $\omega$
and $\rho$ within the spin-isospin decomposition of the regular representation
\rhdmulti{15}. Chirally symmetric SU(2)$\times$SU(2) hadron interactions are
then associated with transformations of a subgroup of SU(4). Nucleon and Delta
resonance states are represented by a symmetric third rank tensor \rhdmulti{20}
whose spin-isospin decomposition leads to $4\oplus 16$ `tower states' also
known from the large-N$_c$ limit of QCD. Towards a relativistic hadron theory,
we consider possible generalizations of the stereographic projection {\bf
S}$^{2}$ $\to$ {\bf C} and the related complex spinorial calculus {\it on the
basis of the division algebras with unit element}. Such a geometrical framework
leads directly to transformations in a quaternionic projective `plane' and the
related symmetry group SL(2,{\bf H}). In exploiting the Lie algebra isomorphism
sl(2,{\bf H}) $\cong$ su$*$(4) $\cong$ so(5,1), we focus on the Lie algebra
su$*$(4) to construct quaternionic Dirac-like spinors, the associated Clifford
algebra and the relation to SU(4) by Weyl's unitary trick. The algebra so(5,1)
contains the de Sitter-algebra so(4,1) which can be contracted to the algebra
of the Poincar\'e group.


title: Supersymmetry: From the Fermi Scale to the Planck Scale

abstract:
  The physics of supersymmetry is reviewed from the perspective of physics at
ever increasing energies. Starting from the minimal supersymmetric extension of
the Standard Model at the electroweak scale, we proceed to higher energies
seeking to understand the origin of the many model parameters. Supersymmetric
grand unification, supergravity, and superstrings are introduced sequentially,
and their contribution to the sought explanations is discussed. Typical
low-energy supersymmetric models are also presented, along with their possible
experimental consequences via direct and indirect processes at high-energy
physics experimental facilities.
  Contents
  1. Introduction
  2. Low-energy Supersymmetry
  3. Supersymmetric Grand Unification
  4. Supergravity
  5. Superstrings
  6. Dynamics
  7. Experimental Prospects
  8. Conclusions


title:
Decay Constants of $B$, $B^*$ and $D$, $D^*$ Mesons in Relativistic Mock
  Meson Model

abstract:
  We derive formulas for the decay constants $f_P$ and $f_V$ of pseudoscalar
and vector mesons in the relativistic mock meson model. Using these formulas,
we obtain $f_P$ and $f_V$ of $B_s$, $B_d$, $D_s$, and $D_d$ mesons as functions
of the mock meson parameter $\beta$. Then by using the values of $\beta$ which
are obtained by the variational method in the relativistic quark model, we
obtain the decay constants $f_P$ and $f_V$ of the heavy mesons, and the
corresponding ratios $f_V/f_P$. The results are compared with other
calculations and existing experimental results.


title: Soft Photoproduction Physics

abstract:
  Several topics of interest in soft photoproduction physics are discussed.
These include jet universality issues (particle flavour composition), the
subdivision into event classes, the buildup of the total photoproduction cross
section and the effects of multiple interactions.


title:
Real next-to-leading corrections to the multigluon amplitudes in the
  helicity formalism

abstract:
  Using the helicity formalism, we compute the corrections to the tree-level
multigluon amplitudes in the high-energy limit, induced by the corrections to
the multi-Regge kinematics, and we show that they coincide with the
corresponding Fadin-Lipatov amplitudes at fixed helicities.


title: QCD Event Generators

abstract:
  This report is a survey on QCD Event Generator issues of relevance for LEP 2.
It contains four main sections: a summary of experience from LEP 1,
extrapolations to LEP 2 energies, Monte Carlo descriptions and standardization
issues.


title:
What are effective $a_1$ and $a_2$ in two-body hadronic decays of D and
  B mesons?

abstract:
  Through a specific example of two-body color-favored charm decay, $D_s ^+
\rightarrow \phi \pi^+$, we illustrate how an effective and complex
(unitarized) $a_1$, denoted by $a_1^{U,eff}$, may be defined such that it
includes nonfactorized, annihilation and inelastic final state interaction
(fsi) effects. The procedure can be generalized to color-suppressed processes
to define an effective, and complex $a_2^{U,eff}$. We determine $|a_1^{U,eff}|$
and, where relevant, $|a_2^{U,eff}|$ for $D\rightarrow \bar{K}\pi, \bar{K}
\rho, \bar{K}^{*} \pi, D_s^+ \rightarrow \eta \pi^+$, $\eta' \pi^+$, $\eta
\rho^+ ,\eta' \rho^+$, and for $B^0 \rightarrow D^- \pi^+$ and $D^- \rho^+$
from the hadronic and semileptonic decay data.


title:
Analysis of the HELIOS-3 $\mu^+\mu^-$ Data within a Relativistic
  Transport Approach

abstract:
  We present a nonperturbative dynamical study of $\mu^+\mu^-$ production in
proton-nucleus and nucleus-nucleus collisions at SPS energies on the basis of
the covariant transport approach HSD. For p + W reactions at 200 GeV bombarding
energy the dimuon yield for invariant masses m $\leq $ 1.6 GeV is found to be
dominated by the decays of the $\eta, \rho, \omega$ and $\Phi$ mesons. For 200
GeV/A S + W collisions, however, the dimuon yield shows an additional large
contribution from $\pi^+\pi^-$, $K^+K^-$ and $\pi \rho$ channels. We find that
for `free' meson masses and form factors the experimental cross section is
clearly underestimated for S + W in the invariant mass range 0.35 GeV $\leq$ m
$\leq$ 0.65 GeV and that the HELIOS-3 data can only be reproduced within a
hadronic scenario, if the $\rho/\omega$-meson mass drops with baryon density.
This finding suggests a partial restoration of chiral symmetry in S + W
collisions at SPS energies.


title:
Renormalization Scale Setting for Evolution Equation of Non-Singlet
  Structure Functions and Their Moments

abstract:
  We use the BLM procedure to eliminate the renormalization scale ambiguity in
the evolution equation for the non-singlet deep-inelastic structure function
$F_2^{\text NS}(x,Q).$ The scale of the QCD coupling in the
$\overline{\text{MS}}$ scheme has the form $Q^*(x) = Q (1-x)^{1/2} / x~f(x) $,
where $x$ is the Bjorken variable and $f(x)$ is a smoothly varying function
bounded between 0.30 to 0.45. Equivalently, the evolution of the $n$th moment
of the structure function should contain an effective $\Lambda_{\text{QCD}}$
pattern, with $\Lambda_n \sim n^{1/2}$. This variation of $\Lambda_n$ agrees
with experimental data.


title: The High Temperature Phase of QCD and {\boldmath $U(1)_A$} Symmetry

abstract:
  Inequalities for QCD functional integrals are used to establish that up to
certain technical assumptions. the high temperature chirally restored phase of
QCD is effectively symmetric under $U(N_f) \times U(N_f)$ rather than $SU(N_f)
\times SU(N_f)$. If these assumptions are correct, there are no effects due to
anomalous breaking of $U(1)_A$ on correlation functions in this phase.


title: Signatures of Technicolor Models with the GIM Mechanism

abstract:
  We investigate the production and the decays of pseudo-Goldstone bosons
(PGBs) predicted by technicolor theories with the GIM mechanism (TC-GIM). The
TC-GIM models contain exotic fermion families that do not interact under weak
$SU(2)$, but they do have color and hypercharge interactions. These fermions
form PGBs, which are the lightest exotic particles in the TC-GIM models. The
spectrum of PGBs consists of color octets, leptoquarks and neutral particles.
The masses of leptoquarks and color octets depend on a free parameter - the
scale of confining interactions. Characteristic for TC-GIM models is a very
light (approx 1 GeV) neutral particle with anomalous couplings to gauge boson
pairs. We show how current experiments constrain the free parameters of the
models. The best tests are provided by the pp --> TT and e^+e^- --> P^0 gamma
reactions. Experiments at LHC and NLC can find PGBs of TC-GIM models in a wide
range of parameter space. However, TC-GIM models can be distinguished from
other TC models only if several PGBs are discovered.


title: Rare, Leptonic, and Hadronic Decays of Charmed Mesons - A Review -

abstract:
  We review the physics of rare, leptonic, and hadronic decays of charmed
mesons based on the results submitted to this conference (EPS 95, Brussles).


title: QCD Sum Rules and Chiral Symmetry Breaking

abstract:
  By matching the world of hadrons to that of some effective chiral quark
theory, we determine the induced condensates for QCD sum rules in the presence
of an external pion field. The observed values of the strong and weak $\pi NN$
coupling constants are understood.


title:
OEDIPUS: Onium Evolution, Dipole Interaction and Perturbative
  Unitarisation Simulation

abstract:
  A Monte Carlo simulation program is presented which can be used to determine
the small-$x$ evolution of a heavy onium using Mueller's colour dipole
formulation, giving the full distribution of dipoles in rapidity and impact
parameter. Routines are also provided which calculate onium-onium scattering
amplitudes between individual pairs of onium configurations, making it possible
to establish the contribution of multiple pomeron exchange terms to onium-onium
scattering (the unitarisation corrections).


title:
New type of beam size effect and the $W$-boson production at
  $\mu^+\mu^-$ colliders

abstract:
  The cross section for the reactions of the type $\mu^-\mu^+ \to e\bar\nu_e X$
can not be calculated by the standard methods due to the $t$--channel
singularity in the physical region. In this letter we show that accounting for
the finite sizes of the colliding beams results in the regularization of this
singularity. The finite cross section, which is obtained in this way, turns out
to be linear proportional to the transverse sizes of the colliding beams. As an
application of the above result, we calculate the cross section of the $W$
boson production at $\mu^+\mu^-$ colliders in the reaction $\mu^- \mu^+ \to
e\bar\nu _e W^+$.


title: Looking Beyond the Standard Model through Precision Electroweak Physics

abstract:
  The most important hint of physics beyond the Standard Model (SM) from the
1995 precision electroweak data is that the most precisely measured quantities,
the total, leptonic and hadronic decay widths of the $Z$ and the effective weak
mixing angle, $\sin^2\theta_W$, measured at LEP and SLC, and the quark-lepton
universality of the weak charged currents measured at low energies, all agree
with the predictions of the SM at a few $\times 10^{-3}$ level. By taking into
account the above constraints I examine implications of three possible
disagreements between experiments and the SM predictions. It is difficult to
interpret the 11\% (2.5-$\sigma$) deficit of the $Z$-partial-width ratio
$R_c=\Gamma_c/\Gamma_h$, since it either implies an unacceptably large
$\alpha_s$ or a subtle cancellation among hadronic $Z$ decay widths in order to
keep all the other successful predictions of the SM. The 2\% (3-$\sigma$)
excess of the ratio $R_b=\Gamma_b/\Gamma_h$ may indicate the presence of a new
rather strong interaction, such as the top-quark Yukawa coupling in the
supersymmetric (SUSY) SM or a new interaction responsible for the large
top-quark mass in the Technicolor scenario of dynamical electroweak symmetry
breaking. Another interpretation may be additional tree-level gauge
interactions that couple only to the third generation of fermions. A common
consequence of these attempts is a rather small $\alpha_s$, $\alpha_s(\mz
)_{\msbar}=0.104\pm 0.08$. The 0.17\% (1-$\sigma$) deficit ...


title:
Restoration of chiral symmetry in quark models with effective one gluon
  exchange

abstract:
  The restoration of chiral symmetry at finite density and/or temperature is
investigated in a wide class of one-gluon exchange models in the instantaneous
approximation. If the effective quark interaction is less divergent than
$1/k^2$ for small momentum transfer $k$, we obtain Gaussian critical exponents
for the chiral phase transitions at finite temperature and density,
respectively. In the opposite case, for an interaction diverging faster than
$1/k^2$ in the infrared region, a qualitative different behavior of the quark
self-energy near the critical Fermi momentum $k_c$ and the critical temperature
$T_c$, respectively, is observed. In the first scenario, we find $k_c \approx 2
\ln 2 \; T_c$, which compares well with recent data from QCD lattice
simulations.


title: Standard Model Processes at LEP2

abstract:
  We present the results obtained by the Standard Model Process group in the
CERN Workshop "Physics at LEP2" (1994/95).


title: FCNC in SUSY Theories

abstract:
  Recent work on flavour changing neutral current effects in supersymmetric
models is reviewed. The emphasis is put on new issues related to solutions to
the flavour problem through new symmetries: GUTs, horizontal symmetries,
modular invariances.


title:
A new CP violation mechanism generated by the standard neutral Higgs
  boson : the $\eta \to \pi + \pi $ case

abstract:
  Strictly within the standard electro-weak interaction, CP violation in the
flavour conserving process $\eta \rightarrow \pi + \pi $ could originate from
the mixing of the $\eta$ meson with the virtual scalar Higgs boson $ H^{0}$ via
$W$ and top quark exchange. The parity-violation carried by weak gauge bosons
makes the mixing possible by quantum effect at two-loop level. Nowhere the
Kobayashi-Maskawa (KM) phase mechanism is needed. The phenomenon reveals an
unexpected new role of the Higgs boson in the CP symmetry breaking. For the
Higgs mass between 100-600 GeV, the $\eta \rightarrow \pi +\pi $ branching
ratio is found to be $3.6 \cdot 10^{-26} - 2.4 \cdot 10^{-29}$ , hence CP
violation mechanisms beyond the Standard Model are the only ones that could
give rise to its observation at existing or near future $\eta$ factories,
unless the Higgs mass is improbably as light as 550 $MeV$.


title: The boson-boson bound state in the massive Schwinger model

abstract:
  We use (fermion) mass perturbation theory for the massive Schwinger model to
compute the boson-boson bound state mass in lowest order. For small fermion
mass the lowest possible Fock state turns out to give the main contribution and
leads to a second order result for the bound state mass.


title: Perturbative solution of the Schwinger model

abstract:
  For the exactly solvable Schwinger model one interesting question is how to
infer the exact solution from perturbation theory. We give a systematic
procedure of deriving the exact solution from Feynman diagrams of arbitrary
order for arbitrary $n$-point functions. As a byproduct, from perturbation
theory we derive exact integral equations that the $n$-point functions have to
obey.


title: Unstable states in QED of strong magnetic fields

abstract:
  We question the use of stable asymptotic scattering states in QED of strong
magnetic fields. To correctly describe excited Landau states and photons above
the pair creation threshold the asymptotic fields are chosen as generalized
Licht fields. In this way the off-shell behavior of unstable particles is
automatically taken into account, and the resonant divergences that occur in
scattering cross sections in the presence of a strong external magnetic field
are avoided. While in a limiting case the conventional electron propagator with
Breit-Wigner form is obtained, in this formalism it is also possible to
calculate $S$-matrix elements with external unstable particles.


title: Chargino Production at LEP2 in a Supergravity Model

abstract:
  In the framework of a particular supergravity model which provides a natural
solution to the $\mu$--problem we show how the discovery of a chargino at LEP2
and the measurement of its mass and production cross--section, together with
the measurement of the mass of the lightest neutralino, would determine the
entire Higgs and SUSY spectrum. We give detailed predictions for the Higgs and
SUSY spectrum as a function of the chargino production cross--section, for
constant values of the lightest chargino and gluino masses.


title: A New Hypothesis on the Origin of the Three Generations

abstract:
  We suggest that the Standard Model may undergo a supercritical transition
near the Landau scale, where the U(1) gauge boson couples to the left and right
handed states of any given fermion with different charges. This scenario
naturally gives rise to three generations of fermion, corresponding to the
three critical scales for the right-right, right-left and left-left fermion
interactions going supercritical, as well as CP violation in the quark sector.


title: Heavy fermions virtual effects at e^+ e^- colliders

abstract:
  We derive the low-energy electroweak effective lagrangian for the case of
additional heavy, unmixed, sequential fermions. Present LEP1 data still allow
for the presence of a new quark and/or lepton doublet with masses greater than
$M_Z/2$, provided that these multiplets are sufficiently degenerate. Keeping in
mind this constraint, we analyse the virtual effects of heavy chiral fermions
in $e^+ e^- \raw W^+ W^-$ process at energies $\sqrt{p^2} = 200,~500,~1000$
GeV, provided by LEP2 and Next Linear Collider. The effects will be
unobservable at LEP2, being smaller than $3.0\cdot 10^{-3}$, while more
interesting is the case of NLC, where an enhancement factor, due to a delay of
unitarity, gives deviations from SM of the order 10-50 per cent, for a wide
range of new fermions masses.


title: Triple Gauge Boson Couplings

abstract:
  We present the results obtained by the "Triple Gauge Couplings" working group
during the LEP2 Workshop (1994-1995). The report concentrates on the
measurement of $WW\gamma$ and $WWZ$ couplings in $e^-e^+\to W^-W^+$ or, more
generally, four-fermion production at LEP2. In addition the detection of new
interactions in the bosonic sector via other production channels is discussed.


title: Bounds on the light quark masses

abstract:
  The corrections to the current algebra mass formulae for the pseudoscalar
mesons are analyzed by means of a simultaneous exansion in powers of the light
quark masses and powers of 1/N. A set of mass formulae is derived, including an
inequality, which leads to bounds for ratios of quark masses.


title:
Quark Model Description of Polarised Deep Inelastic Scattering and the
  prediction of $g_2$

abstract:
  We show how the operator product expansion evaluated in the approximation of
ignoring gluons leads to the covariant formulation of the quark parton model.
We discuss the connection with other formulations and show how the free quark
model prediction, $g_2=0$, changes smoothly into the Wandzura-Wilczek (WW)
relation for quark masses small relative to the nucleon mass. Previous
contradictory parton model predictions are shown to follow from an inconsistent
treatment of the mass shell conditions. The description is extended to include
quark mass corrections.


title: Implications of eta-etaprime mixing for the decay eta->3 pi

abstract:
  Taken by itself, the interference with the etaprime appears to strongly
affect the amplitude of the transition eta->3 pi. I point out that this effect
is fictitious and also occurs in the mass spectrum of the pseudoscalars. Chiral
symmetry implies that the same combination of effective coupling constants
which determines the small deviations from the Gell-Mann-Okubo formula also
specifies the symmetry breaking effects in the decay amplitude and thus ensures
that these are small.


title: Dispersive analysis of the decay eta -> 3 pi

abstract:
  We demonstrate that the decay eta -> 3 pi represents a sensitive probe for
the breaking of chiral symmetry by the quark masses. The transition amplitude
is proportional to the mass ratio (m_d^2-m_u^2)/(m_s^2-m^2). The factor of
proportionality is calculated by means of dispersion relations, using chiral
perturbation theory to determine the subtraction constants. The theoretical
uncertainties in the result are shown to be remarkably small, so that eta-decay
may be used to accurately measure this ratio of quark masses.


title: New Low-Energy Realization of the Superstring-Inspired E_6 Model

abstract:
  The superstring-inspired E_6 model is reduced to the supersymmetric standard
model extended by a specific U(1) factor. This choice allows for the existence
of naturally light singlet neutrinos which also mix with the known three
doublet neutrinos, thus making it possible to accommodate all present neutrino
data. Other consequences of this model are also discussed: oblique corrections
from Z-Z' mixing, phenomenology of the two-Higgs-doublet sector, and possible
scenarios of gauge-coupling unification.


title:
Summary of the International Symposium on Heavy Flavor and Electroweak
  Theory

abstract:
  This summary discusses some of the topics which were of overarching interest
at the Symposium. These included, corrections to perturbative QCD predictions;
heavy quark physics; electroweak symmetry breaking; and physics of the top
quark.


title: High Energy Electron Proton Scattering in View of Born Approximation

abstract:
  The hadronic quark structure is investigated in the frame of high energy
electron proton scattering. A phenomenological model based on the Born
approximation is used to calculate the transition matrix element for the quark
system forming the proton target. A potential of electromagnetic nature is
assumed for the calculation of the multiple scattering of electron with the
constituent valance quarks of the proton. It is found that the first two terms
of the Born approximation are sufficient to describe the experimental data of
differential cross section for the electron proton system only at low momentum
transfer square. On the other hand, a two body scattering amplitude with a
relevant form factor may give proper agreement extended to high momentum
transfer square region. A harmonic oscillator wave function is used to
reproduce the data of the experiment at low momentum transfer. This satisfies
quietly the confinement condition of the quarks in the hadron system. However
the data of the experiment at relatively high momentum transfer, show that
hadronic quarks behave more freely and may be described by just a Coulomb wave
function.
  PACS: 13.40.Fn , 25.40.Cm


title: Dynamical Gauge Coupling Constants

abstract:
  In string theory the coupling parameters are functions of moduli fields. The
actual values of the coupling constants are then dynamically determined through
the vacuum expextation values of these fields. We review the attempts to
connect such theories to low energy effective field theories with realistic
gauge coupling constants. This includes a discussion of supersymmetry
breakdown, the question of a running dilaton, string threshold calculations and
the possibility of string unification.


title: The Ratio of Gluon Distributions in Sn and C

abstract:
  We calculate the ratio of gluon densities, G^Sn(x)/G^C(x), for 0.01<x<0.1,
from the new high statistics data on F_2^Sn/F_2^C taken by the NM
Collaboration. For small x, the shadowing in the gluon distribution is about
equal to the shadowing of quark distribution. The antishadowing in the gluon
distribution, however, is roughly 10%. We also compare with the ratio
difference, R=sigma_L/sigma_T, from Sn and C.


title: Yukawa textures with an anomalous horizontal abelian symmetry

abstract:
  The observed hierarchy of quark and lepton masses and mixings may be obtained
by adding an abelian family symmetry to the Minimal Supersymmetric Model and
coupling quarks and leptons to an electroweak singlet scalar field. In a large
class of such models, this symmetry suffers from anomalies which must be
compensated by the Green-Schwarz mechanism; this in turn fixes the electroweak
mixing angle to be $\sin^2 \theta_W = 3/8$ at the string scale, without any
assumed GUT structure. The analysis is extended to two distinct generalisations
of the Standard Model: neutrino masses and mixings and R-parity violating
interactions.


title: Sea polarisation and the Drell-Hearn-Gerasimov sum-rule(s)

abstract:
  The Drell-Hearn-Gerasimov sum-rule is really two sum-rules: one for each of
the valence and the sea/glue contributions to the nucleon wavefunction. The
convergence of these sum-rules follows from the Froissart bound for spin
dependent processes in QCD and is necessary for the consistency of the
constituent quark model of low energy QCD. Some challenges for future polarised
photoproduction experiments, for example at ELFE, are discussed.


title: Decay of high-density matter in the electroweak theory

abstract:
  High-density fermion matter is meta-stable due to the anomalous
non-conservation of baryon and lepton numbers in the electroweak theory. The
meta-stable state decays by penetrating the sphaleron barrier separating
topologically different vacua. The decay happens locally, and results in an
annihilation of twelve fermions, accompanied by a production of gauge and Higgs
bosons. We find numerically local bounce solutions determining the decay rate,
which are classical paths in imaginary time, connecting two adjacent
topological sectors. We also follow the real-time evolution of the bosonic
fields after the tunneling and analyze the spectrum of the created bosons.


title: Instanton Effects in the Decay of Scalar Mesons

abstract:
  We show that instanton effects may play a crucial role in the decay of scalar
mesons into two pseudoscalars. Particularly the branching ratios of two meson
decays of the $f_0(1500)$, which is considered as a glue-ball candidate, are
then compatible with an ordinary $q \bar{q}$-structure of this resonance and a
small positive SU(3) mixing angle, close to a result recently calculated with
the same instanton-induced force.


title: Thermal Equilibration in an Expanding Parton Plasma

abstract:
  Thermalization in an expanding parton plasma is studied within the framework
of Boltzmann equation in the absence of any mean fields. In particular, we
study the time-dependence of the relaxation time to the lowest order in finite
temperature QCD and how such time-dependence affects the thermalization of an
expanding parton plasma. Because of Debye screening and Landau damping at
finite temperature, the relaxation time (or transport rates) is free of
infrared divergencies in both longitudinal and transverse interactions. The
resultant relaxation time decreases with time in an expanding plasma like
$1/\tau^\beta$, with $\beta<1$. We prove in this case that thermal equilibrium
will eventually be established given a long life-time of the system. However, a
fixed momentum cut-off in the calculation of the relaxation time gives rise to
a much stronger time dependence which will slow down thermal equilibrium. It is
also demonstrated that the ``memory effect'' of the initial condition affects
the approach to thermal equilibrium and the final entropy production.


title:
Large $N_c$ Universality of The Baryon Isgur--Wise Form Factor: The
  Group Theoretical Approach

abstract:
  In a previous article, it has been proved under the framework of chiral
soliton model that the same Isgur--Wise form factor describes the semileptonic
$\Lambda_b\to\Lambda_c$ and $\Sigma^{(*)}_b\to\Sigma^{(*)}_c$ decays in the
large $N_c$ limit. It is shown here that this result is in fact independent of
the chiral soliton model and is solely the consequence of the spin-flavor SU(4)
symmetry which arises in the baryon sector in the large $N_c$ limit.


title: The $B_c$ Meson Lifetime

abstract:
  We investigate the total inclusive decay rate of the (ground state) $B_c$
meson within the framework of an operator product expansion in inverse powers
of the heavy quark masses and subsequent matching onto nonrelativistic QCD. The
expansion is organized as a series in the strong coupling and in powers of the
heavy quark velocities in the $B_c$, reflecting the nonrelativistic nature of a
heavy-heavy bound state. In this aspect the character of the expansion differs
from the more familiar case of heavy-light mesons. The framework incorporates
systematically corrections to the leading $b$- and $c$-quark decays due to
binding effects, as well as contributions from weak annihilation and Pauli
interference. Based on this approach we find for the $B_c$ meson lifetime
$\tau_{B_c}=(0.4 - 0.7)\,$ps, the dominant mechanism being the decay of the
charm constituent.


title:
A comparison of the non-standard effects of effective theories with
  linearly realized and strongly interacting Higgs sectors

abstract:
  Effective theories provide a powerful tool for testing the Standard Model and
for searching for the effects of new physics in a model-independent manner. In
general one assumes that the effects of new physics characterized by a
high-energy scale may be observed at low-energies only through quantum
corrections. These quantum corrections may be described by effective operators
which are constructed from the fields of the low-energy theory; the
coefficients of these operators may be measured via experiment, but a
theoretical determination is only possible once the complete theory is known.
Because the existence or non-existence of a light physical Higgs boson has not
yet been established the inclusion or exclusion of the Higgs field in the
construction of the effective Lagrangian is open to debate. For this reason we
discuss both the linearly realized effective Lagrangian, which includes a light
physical Higgs boson, and the chiral Lagrangian, where the Higgs boson has been
removed by a formal integration. In each scenario the contributions to oblique
parameters and to W-pair-production amplitudes are discussed. Where possible
relationships between the two effective Lagrangians are given.


title:
Contributions of effective theories with linearly realized and strongly
  interacting Higgs sectors to the process $e^+e^- \to W^+W^-$

abstract:
  Previous form-factor-based analyses of $e^+e^-\to W^+W^-$ have focused upon
non-standard contributions to the $WWZ$ and $WW\gamma$ vertices. A more
complete form-factor-based formalism is presented which allows for more general
corrections, including t-channel corrections. The form factors are then
calculated from an effective Lagrangian. Because the existence or non-existence
of a light physical Higgs boson has not yet been established, both a linearly
realized and a non-linearly realized effective Lagrangian are employed. In
either scenario deviations from the Standard Model occur not only in W-pair
production, but in other sectors as well. Effects in W-pair production are
related to effects detected/constrained by the electroweak precision
measurements. With either realization of the symmetry-breaking sector seven
operators contribute to the process $e^+e^-\to W^+W^-$. In the linear
(non-linear) realization, four (three) of these operators are already
stringently constrained via their contributions to processes with four external
fermions. As a result the parameter space which must be explored is manageable.


title: The rare decay $\eta\to\pi\pi\gamma\gamma$ in chiral perturbation theory

abstract:
  We investigate the rare radiative eta decay modes
$\eta\to\pi^+\pi^-\gamma\gamma$ and $\eta\to\pi^0\pi^0\gamma\gamma$ within the
framework of chiral perturbation theory at $O(p^4)$. We present photon spectra
and partial decay rates for both processes as well as a Dalitz contour plot for
the charged decay.