title:
Charged Higgs mass bound from the $b\rightarrow s\gamma$ process in the
  minimal supergravity model

abstract:
  We study the constraint on the mass of the charged Higgs boson in the minimal
supergravity model based on the recent measurement of the inclusive
$b\rightarrow s\gamma$ decay. It is shown that the lower bound for the charged
Higgs mass crucially depends on the sign of the higgsino mass parameter
($\mu$). For $\mu<0$, the bound exceeds 400 GeV when the ratio of two Higgs
vacuum expectation values ($\tan\beta$) is larger than 10. No strong bound is
obtained for $\mu>0$ due to cancellations between charged Higgs and
supersymmetric particle contributions. For $3\lsim\tan\beta\lsim5$, a charged
Higgs lighter than 180 GeV is excluded by this process irrespective of the sign
of $\mu$.


title: Heavy-to-Light Form Factors from QCD Sum Rules on the Light-Cone

abstract:
  We discuss the calculation of the $B \rightarrow \pi$ and $D \rightarrow \pi$
form factors based on an expansion in terms of pion wave functions on the
light-cone with increasing twist and QCD sum rule methods. The results are
compared with predictions of conventional QCD sum rules and other approaches.


title:
The Expected, The Promised and The Conceivable -- On CP Violation in
  Beauty and Charm Decays

abstract:
  the KM expectations of large CP asymmetries in $B$ decays are reviewed. I
describe some observable signatures for the intervention of New Physics and
list benchmarks defining the `ultimate' measurements in beauty physics. I also
stress the need for dedicated searches for CP asymmetries in $D$ decays;
attaining a sensitivity level of $10^{-3}$ could well reveal New Physics and
thus lead to a new paradigm.


title: Quenched Chiral Corrections to Heavy-Light Decay Constants at Order 1/M

abstract:
  Quenched chiral perturbation is used to study the decay constants for
heavy-light mesons beyond the leading order in 1/M. The results are used to
estimate the error in quenched lattice calculations of the decay constants. For
the double ratio $R_1 = ( f_{D_s}/f_D) / (f_{B_s}/f_B)$ we find that the error
is small, conservatively 6%, but likely smaller. We also find that quenching
decreases the ratio $f_{D_s}/f_D$ relative to the unquenched theory.


title: The $B \to K^\ast \psi$ Polarization Puzzle

abstract:
  We point out that current estimates of form factors fail to explain the
non-leptonic decays $B \to \psi K(K^{\ast})$ and that the combination of data
on the semi-leptonic decays $D \to K(K^{\ast})\ell \nu$ and on the non-leptonic
decays $B \to \psi K(K^{\ast})$ (in particular recent po\-la\-ri\-za\-tion
data) severely constrain the form (normalization and $q^2$ dependence) of the
heavy-to-light meson form factors, if we assume the factorization hypothesis
for the latter. From a simultaneous fit to \bpsi and \dk data we find that
strict heavy quark limit scaling laws applied to the form factors do not hold
when going from $D$ to $B$ and must have large corrections that make softer the
dependence on the masses. This is in contrast with the matrix elements
themselves which are found to need smaller $1/m_Q$ corrections to the
asymptotic heavy quark scaling laws. We also find that $A_1(q^2)$ should
increase slower with \qq than $A_2, V, f_+$. We propose a simple
parametrization of these corrections based on a quark model or on an extension
of the \hhs laws to the \hl case, complemented with an approximately constant
$A_1(q^2)$. This model may be viewed as assuming a precocious validity of
strict heavy quark scaling laws for the current matrix elements. Although this
model reproduces qualitatively the wanted features for mass and $q^2$
dependence, and thus reduces the discrepancy with data, it is insufficient to
reach a full agreement with the experiment. In our opinion the puzzle is still
there.


title:
Spin-Momentum Correlation (Handedness) in the Process of Four Pions
  Production in the Electron-Positron Collisions

abstract:
  We discuss special type of polarization asymmetry (``handedness") in the
process $e^+e^-\to 4\pi$, when one of initial particles is longitudinally
polarized. The asymmetry is proportional to the degree of polarization and to
the width to mass ratio of rho-meson. It can reach 4-5\% in some kinematical
region. Both channels $2 \pi^+ 2 \pi^-$ and $2 \pi^0 \pi^+ \pi^-$ are
considered in the framework of the effective chiral lagrangian with vector
mesons, in the energy range $\sim 1$ GeV. The corresponding total cross
sections are also calculated.


title: Systematics of the Light and Strange Baryons and the Symmetries of QCD

abstract:
  The spectra of the nucleons and the strange hyperons are well described by a
harmonic confinement potential for the constituent quarks and an SU(3)
flavor-symmetric interaction mediated by the pseudoscalar octet that is
associated with the hidden approximate chiral symmetry of QCD. The spectrum is
formed of multiplets of $SU(6)_{FS}\times U(6)_{conf}$, which are mixed by the
octet interaction. With 4 matrix elements of the octet mediated interaction
determined by the lowest mass splittings in the nucleon spectrum the resulting
mass formula predicts the whole spectrum with an accuracy of $\sim$ 5\%.


title: A Note on the Finiteness of Curvature at Cosmic String Cusps

abstract:
  We examine a Nambu-Goto string trajectory in the neighbourhood of a cusp and
determine the extrinsic curvature invariants. These are demonstrated to be
finite, in contradiction with naive expectation. Thus the Nambu action is a
valid approximation for the motion of a cosmic string vortex even at cusps.
This suggests that cusp annihilation is not a feasible mechanism for particle
radiation from cosmic strings.


title:
Do the Age of the Universe and the Hubble Constant Depend on What Scale
  One Observes Them?

abstract:
  The apparent cosmological conflict between the age of the Universe, predicted
in the standard Friedman cosmology by using the recent measurement of the
larger Hubble constant from a direct calibration of the distance to the Virgo
galaxy cluster, and the ages of the oldest stars and globular clusters is
resolved by invoking the scale dependence of cosmological quantities, including
the age of the Universe. The distance dependence or the running of cosmological
quantities is motivated by the asymptotically-free higher- derivative quantum
gravity. The running can also be derived by ``properly" modifying the Friedman
equations. This property can also provide partial explanation of the apparent
disagreement between the two recent measurements of the Hubble constant using
NGC 4571 at 15 Mpc and NGC 5253 at 4 Mpc.


title:
Theoretical Motivation for Gravitation Experiments on Ultra-Low Energy
  Antiprotons and Antihydrogen

abstract:
  We know that the generally accepted theories of gravity and quantum mechanics
are fundamentally incompatible. Thus, when we try to combine these theories, we
must beware of physical pitfalls. Modern theories of quantum gravity are trying
to overcome these problems. Any ideas must confront the present agreement with
general relativity, but yet be free to wonder about not understood phenomena,
such as the dark matter problem and the anomalous spacecraft data which we
announce here. This all has led some ``intrepid" theorists to consider a new
gravitational regime, that of antimatter. Even more ``daring" experimentalists
are attempting, or considering attempting, the measurement of the gravitational
force on antimatter, including low-energy antiprotons and, perhaps most
enticing, antihydrogen.


title: The Nucleon's Tensor Charge

abstract:
  We seek to understand the physical significance of the nucleon's tensor
charge and make estimates of its size in phenomenological models and the QCD
sum rule.


title:
Improved analysis of the renormalization scheme ambiguities in the QCD
  corrections to the semileptonic decay of the tau lepton

abstract:
  The perturbative QCD corrections to the semileptonic decay width of the tau
lepton are evaluated in the next-next-to-leading order from the contour
integral representation in various renormalization schemes, using numerical
solution of the renormalization group equation for complex energies. A
quantitative estimate of the ambiguities resulting from the freedom of choice
of the renormalization scheme is obtained by taking into account predictions in
all schemes that do not involve large cancellations in the expression for the
scheme invariant combination of the expansion coefficients. The problem of an
optimal choice of the renormalization scheme for the improved perturbative
expression is discussed. A fit of $\Lambda_{\overline{MS}}$ is made using the
available experimental data.


title: Direct detection of dark matter in SU(5)xU(1) supergravity

abstract:
  We compute the scattering rates for the lightest neutralino $\chi^0_1$ in the
forthcoming germanium $(^{73}{\rm Ge}+^{76}{\rm Ge})$ detector and a proposed
lead detector $(^{207}{\rm Pb})$, within the framework of $SU(5)\times U(1)$
supergravity. We find that in only a small portion ($\lsim10\%$) of the
parameter spaces of this class of models, are the rates in the germanium
detector above the expected initial experimental sensitivity of 0.1
events/kg/day. However, a much larger portion ($\lsim40\%$) of the parameter
spaces could be probed with an improved background rejection capability (0.01
events/kg/day) and/or a more sensitive detector $(^{207}{\rm Pb})$.


title: Methods of calculation of higher power corrections in QCD

abstract:
  Although the methods of calculation of power corrections in QCD sum rules are
well known, algebraic complexity rapidly grows with the increase of vacuum
condensates' dimensions. Currently, state-of-the-art calculations include
dimension 7 and 8 condensates. I summarize and extend algorithms of such
calculations. First, I present all the formulae necessary for application of
the systematic classification of bilinear quark condensates proposed earlier,
and extend this method to the case of gluon condensates. Then I apply these
systematic procedures to expansions of bilinear and noncollinear quark and
gluon condensates in local ones, and of noncollinear condensates in bilocal
ones. The formulae obtained can be used for calculation of correlators
involving nonlocal condensates, and for inventing consistent anzatzs for these
condensates. Finally, I briefly summarize the methods of calculation of heavy-
and light-quark currents' correlators. This paper is aimed both to present new
results on gluon and nonlocal condensates and to be a self-contained handbook
of formulae necessary for calculation of power corrections in QCD sum rules.


title: Chromo- and Electrodynamics of Heavy Unstable Particle

abstract:
  In this talk I attempt to survey some selected physics issues on radiative
interference phenomena in the production of heavy unstable particles. A special
emphasis is placed on the reactions $e^+e^- \rightarrow W^+W^- \rightarrow 4$
jets and $e^+e^- \rightarrow t\bar{t} \rightarrow bW^+\bar{b}W^-$. A
transparent recipe is given for quantifying the level of suppression of the
interference effects in the inclusive production processes. The influence of
the $W$ width on the Coulomb corrections to the threshold $W^+W^-$ production
is briefly addressed.


title:
A small non-vanishing cosmological constant from vacuum energy:
  physically and observationally desirable

abstract:
  Increasing improvements in the independent determinations of the Hubble
constant and the age of the universe now seem to indicate that we need a small
non-vanishing cosmological constant to make the two independent observations
consistent with each other. The cosmological constant can be physically
interpreted as due to the vacuum energy of quantized fields. To make the
cosmological observations consistent with each other we would need a vacuum
energy density, $ \rho_v \sim (10^{-3} eV)^4 $ today ( in the cosmological
units $ \hbar=c=k=1 $ ). It is argued in this article that such a vacuum energy
density is natural in the context of phase transitions linked to massive
neutrinos. In fact, the neutrino masses required to provide the right vacuum
energy scale to remove the age Vs Hubble constant discrepancy are consistent
with those required to solve the solar neutrino problem by the MSW mechanism.


title: Numerical studies of instanton induced baryon decay

abstract:
  We describe an application of computational techniques to the study of
instanton induced baryon decay in high energy electroweak interactions.


title:
From Tetraquark to Hexaquark: A Systematic Study of Heavy Exotics in the
  Large $N_c$ Limit

abstract:
  A systematic study of multiquark exotics with one or $N_c-1$ heavy quarks in
the large $N_c$ limit is presented. By binding a chiral soliton to a heavy
meson, either a normal $N_c$-quark baryon or an exotic $(N_c+2)$-quark baryon
is obtained. By replacing the heavy quark with $N_c-1$ heavy antiquarks, exotic
$(2N_c-2)$-quark and $2N_c$-quark mesons are obtained. When $N_c = 3$, they are
just the normal triquark baryon $Qqq$, the exotic pentaquark baryon $Q\bar
q\bar q\bar q\bar q$, tetraquark di-meson $\bar Q \bar Q qq$ and the hexaquark
di-baryon $\bar Q \bar Q \bar q \bar q\ bar q \bar q$ respectively. Their
stabilities and decays are also discussed. In particular, it is shown that the
``heavy to heavy'' semileptonic decays are described by the Isgur--Wise form
factors of the normal baryons.


title: Phenomenology from the Lattice

abstract:
  This is the written version of four lectures given at the 1994 TASI. My aim
is to explain the essentials of lattice calculations, give an update on (though
not a review of) the present status of calculations of phenomenologically
interesting quantities, and to provide an understanding of the various sources
of uncertainty in the results. I illustrate the important issues using the
examples of the kaon B-parameter ($B_K$) and various quantities related to
$B$-meson physics. Contents: 1. Why do we need lattice QCD? 2. Basics of
Euclidean Lattice Field Theory. 3. Discretizing QCD. 4. Simulations. 5.
Numerical Results from quenched QCD. 6. Anatomy of a calculation: $B_K$. 7.
Heavy mesons on the lattice. 8. A final flourish


title: Light-Front Dynamics and Light-Front QCD

abstract:
  In this article we review the basic formulation of light-front field theory
and light-front phenomena in strong interaction. We also explore various
approaches to the understanding of these phenomena and the associated problems
of hadronic bound states based on QCD (quantum chromodynamics) on the
light-front.


title: Production of Heavy Selectrons in Electron-Photon Collisions

abstract:
  We study the production and decay of heavy selectrons in the electron-photon
mode of a linear collider of the next generation. The standard model
backgrounds can be substantially reduced by appropriate kinematical cuts. As a
consequence, selectrons far heavier than the kinematical threshold for pair
production are shown to be easily discoverable for large portions of the
supersymmetry parameter space. We also describe a model-independent kinematical
measurement of the mass of the lightest neutralino.


title:
Constraining Spectral Functions at Finite Temperature and Chemical
  Potential with Exact Sum Rules in Asymptotically Free Theories

abstract:
  Within the framework of the operator product expansion (OPE) and the
renormalization group equation (RGE), we show that the temperature and chemical
potential dependence of the zeroth moment of a spectral function (SF) is
completely determined by the one-loop structure in an asymptotically free
theory, and in particular in QCD. Logarithmic corrections are found to play an
essential role in the derivation. This exact result constrains the shape of
SF's, and implies striking effects near phase transitions. Phenomenological
parameterizations of the SF, often used in applications such as the analysis of
lattice QCD data or QCD sum rule calculations at finite temperature and baryon
density must satisfy these constraints. We also explicitly illustrate in detail
the exact sum rule in the Gross-Neveu model.


title:
Upper Bound on the Mass of Lightest Higgs Boson in the Supersymmetric
  Majoran Model

abstract:
  We calculate an upper bound on the lightest Higgs boson mass in the
supersymmetric singlet majoran model containing SU(2) X U(1) singlet right
handed neutrino fields and a chiral singlet having two units of lepton number.
We show that although the singlet vacuum expectation values and supersymmetry
breaking masses do not decouple from the upper bound, even at the tree level,
their effect is small, thereby reducing the bound to the corresponding bound in
the Minimal Supersymmetric Standard Model. Radiative corrections to the bound
are similar to those in the minimal model. We also show that the couplings of
the lightest Higgs boson to the majorans are suppressed in this model.


title:
Effective Lagrangian Approach to the Theory of Eta Photoproduction in
  the $N^{*}(1535)$ Region

abstract:
  We investigate eta photoproduction in the $N^{*}(1535)$ resonance region
within the effective Lagrangian approach (ELA), wherein leading contributions
to the amplitude at the tree level are taken into account. These include the
nucleon Born terms and the leading $t$-channel vector meson exchanges as the
non-resonant pieces. In addition, we consider five resonance contributions in
the $s$- and $u$- channel; besides the dominant $N^{*}(1535)$, these are:
$N^{*}(1440),N^{*}(1520),N^{*}(1650)$ and $N^{*}(1710)$. The amplitudes for the
$\pi^\circ$ and the $\eta$ photoproduction near threshold have significant
differences, even as they share common contributions, such as those of the
nucleon Born terms. Among these differences, the contribution to the $\eta$
photoproduction of the $s$-channel excitation of the $N^{*}(1535)$ is the most
significant. We find the off-shell properties of the spin-3/2 resonances to be
important in determining the background contributions. Fitting our effective
amplitude to the available data base allows us to extract the quantity
$\sqrt{\chi \Gamma_\eta} A_{1/2}/\Gamma_T$, characteristic of the
photoexcitation of the $N^{*}(1535)$ resonance and its decay into the
$\eta$-nucleon channel, of interest to precise tests of hadron models. At the
photon point, we determine it to be $(2.2\pm 0.2)\times 10^{-1} GeV^{-1}$ from
the old data base, and $(2.2\pm 0.1) \times 10^{-1} GeV^{-1}$ from a
combination of old data base and new Bates data. We obtain the helicity
amplitude for $N^{*}(1535)\rightarrow \gamma p$ to be $A_{1/2}=(97\pm 7)\times
10^{-3} GeV^{-1/2}$ from the old data base, and $A_{1/2}=(97\pm 6)\times
10^{-3} GeV^{-1/2}$ from the combination of the old data base and new Bates
data, compared with the results of the analysis of pion photoproduction
yielding $74\pm 11$, in the same units.


title: Production Mechanisms for $B_c$ Mesons in Photon--Photon Collisions

abstract:
  Using photon-photon collisions as a particularly transparent study case we
investigate the production mechanisms for $B_c$ mesons. In nonrelativistic
approximation and to $O(\alpha^2\alpha_s^2)$ it is shown that recombination of
$\bar{b}$- and $c$-quarks dominates by far over $\bar{b}$ and $c$
fragmentation. This dominance persists up to the highest accessible transverse
momenta and leads to distributions in energy which differ completely from the
spectra expected on the basis of the fragmentation functions. For processes in
which a $b \bar{b}$-pair is radiated from a primary $c$-quark, the
fragmentation description is found to be inadequate. We anticipate important
implications of these results for hadronic production of heavy quark
resonances. Using realistic photon spectra we predict two-photon production
rates for $B_c$ and $B_c^*$ at present and future $e^+e^-$-machines.


title: Finite Width Effects in Top Quark Decays

abstract:
  Motivated by evidence that the top quark mass lies near the $bWZ$ threshold,
we compute the decay rate for $t\rightarrow bWZ$ in the Standard Model,
including the effects of the finite widths of the $W$ and $Z$ bosons. In the
limit where the width effects are negligible, our results disagree with
previously published calculations. We also examine the decay $t\rightarrow
bWH$. Although the widths induce a sizable enhancement near threshold for both
decays, we find that the rates are still too small to be observed in the
present generation of experiments. This means that detection of either mode in
one of these experiments would be a signal of new physics.


title: Transition radiation of the neutrino magnetic moment

abstract:
  If the neutrino has a finite mass and a magnetic moment it would produce
transition radiation when crossing the interface between two media. We found
that the probability of transition radiation is larger by an order of magnitude
using the quantum theory than that recently reported by one of us using
classical electrodynamics, and that the energy spectrum of the radiation is
nearly uniform.


title: Pseudo-Goldstone Modes in Isospin-Asymmetric Nuclear Matter

abstract:
  We analyze the chiral limit in dense isospin-asymmetric nuclear matter. It is
shown that the pseudo-Goldstone modes in this system are qualitatively
different from the case of isospin-symmetric matter.


title:
A New Scale-Dependent Cosmology with the Generalized Robertson--Walker
  Metric and Einstein Equation

abstract:
  Based on the observed increase of $\Omega _0$ as a function of cosmic scale,
the Robertson--Walker metric and the Einstein equation are generalized so that
$ \Omega_0$, $H_0$, and the age of the Universe, $t_0$, all become functions of
cosmic scales at which we observe them. The calculated local (within our
galaxy) age of the Universe is about 18 Gyr, consistent with the ages of the
oldest stars and globular clusters in our galaxy, while the ages at distant
scales are shorter than the local age, solving the age puzzle. It is also shown
that $H_0$ increases as scale increases, qualitatively consistent with the
recent observations.


title: CP Violation In Hyperon Decays Due To Left-Right Mixing

abstract:
  We consider CP violation due to left-right mixing in a class of Left-Right
symmetric models and show that it leads to observable effects in hyperon
decays. For S-wave, the contribution to CP violating asymmetry A of the
polarization in hyperon and anti-hyperon decays is proportional to
$\epsilon'/\epsilon$. While the tree level L-R operators contribution is
constrained to be less than $ 10^{-5}$, the gluon penguin operator contribution
can be as large as $10^{-4}$. For P-wave, the contribution is not directly
related to $\epsilon'/\epsilon$. Its contribution to A can be larger and may
reach $6\times 10^{-4}$ in $\Lambda \rightarrow p\pi^-$. This is much larger
than the value expected for A in the Standard Model.


title: ${\cal O}(\alpha_{s})$ Spin-Dependent Weak Structure Functions

abstract:
  The complete next to leading logarithmic (${\cal O}(\alpha_{s})$) corrections
to the spin dependent weak deep inelastic structure functions $g_{1},g_{3}$ and
$g_{4}$, are calculated using dimensional regularization within the HVBM
method. Analysing the quark and gluon initiated contributions to these
corrections for different values for the quark masses, a consistent
factorization prescription for spin dependent quark distributions, which safely
removes soft contributions, is defined. It is shown that within this scheme,
quark initiated corrections are comparable in magnitude to those of gluonic
origin, even though their contributions to the moments are small.


title:
Parity Symmetry Restoration in Qed3 at High Temperature and Finite
  Density

abstract:
  We investigate the properties of quantum electrodynamics $(QED_3)$ in two
spatial dimensions at finite temperature and density. The static as well as the
dynamical properties of the planar plasma are calculated using the real time
formalism of quantum field theory. It is shown, that due to the presence of the
parity breaking Chern-Simons term, the propagating modes of the photon consists
of two longielliptic waves with different values for the masses. However, it is
shown that both in the high temperature and high density limit the parity
symmetry is restored; in this limit the propagating modes reduce to the
longitudinal and transverse ones, both with the same mass.


title:
Dimensional Reduction and Dynamical Chiral Symmetry Breaking by a
  Magnetic Field in $3+1$ Dimensions

abstract:
  It is shown that in $3+1$ dimensions, a constant magnetic field is a catalyst
of dynamical chiral symmetry breaking, leading to generating a fermion mass
even at the weakest attractive interaction between fermions. The essence of
this effect is the dimensional reduction $D \rightarrow D-2$ ($3+1 \rightarrow
1+1$) in the dynamics of fermion pairing in a magnetic field. The effect is
illustrated in the Nambu-Jona-Lasinio model. Possible applications of this
effect are briefly discussed.


title: Electroweak theory at {\boldmath $Z^0$} and above

abstract:
  We present a simple method for considering radiative corrections. Precision
data are well described by an adequate Born approximation and only the first
evidence for deviations from the tree level formulas and the presence of the
loop effects emerge.


title:
$R$--Parity Violating SUSY or Leptoquarks: Virtual Effects in Dilepton
  Production

abstract:
  In the Standard Model (SM), dilepton production in hadron--hadron collisions
proceeds through the conventional Drell--Yan mechanism $q \bar{q} \rightarrow
l^+ l^-$ with the exchange of a gauge boson. Some extensions of the SM contain
a quark--lepton contact interaction {\it via} a $q l \phi$ Yukawa coupling,
where $\phi$ is a scalar. Theories with scalar leptoquarks and $R$--parity
violating SUSY models are the most important examples of such extensions. These
Yukawa couplings induce a different dynamical configuration compared to the SM
($t$-channel vs. $s$-channel) in the $q\bar{q} \rightarrow l^+l^-$ process and
thus offer the possibility of being identifiable upon imposition of suitable
kinematic cuts. We discuss these effects in the context of the dilepton
production in the CDF experiment, and explore consequences in the forthcoming
Large Hadron Collider (LHC).


title: Inconsistency of the SU(3)_L x U(1)_X model

abstract:
  Withdrawn. We thank J. T. Liu for bringing an error in the manuscript to our
attention.


title:
How to obtain a covariant Breit type equation from relativistic
  Constraint Theory

abstract:
  It is shown that, by an appropriate modification of the structure of the
interaction potential, the Breit equation can be incorporated into a set of two
compatible manifestly covariant wave equations, derived from the general rules
of Constraint Theory. The complementary equation to the covariant Breit type
equation determines the evolution law in the relative time variable. The
interaction potential can be systematically calculated in perturbation theory
from Feynman diagrams. The normalization condition of the Breit wave function
is determined. The wave equation is reduced, for general classes of potential,
to a single Pauli-Schr\"odinger type equation. As an application of the
covariant Breit type equation, we exhibit massless pseudoscalar bound state
solutions, corresponding to a particular class of confining potentials.


title:
Supersymmetry Breaking Scheme and The Derivation of $M_{GUT}=10^{16}GeV$
  from A String Model

abstract:
  We propose that a modified version of string-inspired supersymmetry breaking
schemes in \cite{wit2} and \cite{ross} may make affine level one SU(5) and
SO(10) string models with intermediate gauge symmetry breaking scale
$M_{GUT}=10^{16}GeV$ possible; doublet-triplet problem can also be solved. In
particular, we propose that some charged gauge background VEVs might be turned
on when gaugino condensation happens in the hidden sector and would break gauge
symmetry. One can dynamically determine gaugino condensation scale, local
supersymmetry breaking scale and intermediate gauge symmetry breaking scale
$M_{GUT}$ in terms of dilaton VEV. With dilaton VEV, $\langle S \rangle \sim
2$, and $E_6$ hidden sector gaugino condensation, we can obtain
$M_{GUT}=10^{16}GeV$. We also discuss how to generate the mass hierarchy within
the framework of this supersymmetry breaking scheme. We show that the large
mass hierarchy restricts string models to those that have a no-scale structure
and in which the gauge coupling function does not receive string threshold
corrections.


title:
On mean free path statistics of relativistic heavy ions in nuclear
  emulsion

abstract:
  We survey at the general level, and in a rather wide and historical context,
some less known mathematical details of various mean free path statistics in
nuclear emulsion as applied to relativistic projectile fragmentations. A number
of comments are provided on Feller's paradox, ordered, censored, and truncated
statistics, Erlang and Poisson observers of nuclear emulsion. All these issues
are related to the statistical approaches used about a decade ago at Berkeley
Bevalac for anomalons, some of which should be considered as standard methods
for mean free paths' estimators of relativistic heavy ions.


title: Fermi Ball Detection

abstract:
  The detectability of charged SLAC-bag type structures is considered. These
objects, known as Fermi balls, arise from the spontaneous symmetry breaking of
a biased discrete symmetry in the early universe. Two classes of experimental
searches are discussed. Since Fermi balls in the theoretically favoured mass
range are absorbed by the atmosphere, direct experimental searches are confined
to space-based facilities. Simple spectrometer and time of flight analysis give
a quantitative estimate of Fermi ball mass up to a limit set by the system's
tracking resolution. For the ASTROMAG facility, with a tracking resolution of
50 $\mu$m the upper bound on detectable Fermi ball masses is of order $10^{15}$
GeV/c$^{2}$. Charged tracks with sagitta smaller than this resolution would
provide evidence in favour of Fermi balls, but only give a lower bound on the
discrete symmetry breaking scale $\varphi_{0}$. The second class of
experimental search proposed relies on the detection of bound Fermi ball states
that have been concentrated in terrestrial materials such as oceanic sediment.


title: Scale Setting in QCD and the Momentum Flow in Feynman Diagrams

abstract:
  We present a formalism to evaluate QCD diagrams with a single virtual gluon
using a running coupling constant at the vertices. This method, which
corresponds to an all-order resummation of certain terms in a perturbative
series, provides a description of the momentum flow through the gluon
propagator. It can be viewed as a generalization of the scale-setting
prescription of Brodsky, Lepage and Mackenzie to all orders in perturbation
theory. In particular, the approach can be used to investigate why in some
cases the ``typical'' momenta in a loop diagram are different from the
``natural'' scale of the process. It offers an intuitive understanding of the
appearance of infrared renormalons in perturbation theory and their connection
to the rate of convergence of a perturbative series. Moreover, it allows one to
separate short- and long-distance contributions by introducing a hard
factorization scale. Several applications to one- and two-scale problems are
discussed in detail.


title:
Particle Physics Models, Topological Defects and Electroweak
  Baryogenesis

abstract:
  We demonstrate the viability of electroweak baryogenesis scenarios in which
the necessary departure from equilibrium is realized by the evolution of a
network of topological defects. We consider several effective models of TeV
physics, each addressing a fundamental particle physics problem, and in which
the conditions necessary for defect-mediated electroweak baryogenesis are
naturally satisfied. In each case we compare the strength of the model with
that expected from scenarios in which baryogenesis proceeds with the
propagation of critical bubbles.


title: Radiative Corrections to K_l2 decays

abstract:
  We consider $K_{l2}$ decays to the order $O(\alpha)$. We perform a matching
calculation, using a specific model with vector meson dominance in the long
distance part and the parton model in the short distance part. By considering
the dependence on the matching scale and on the hadronic parameters, and by
comparing with the leading model independent predictions, we scrutinize the
model dependence of the results.


title: CP Violation and the Width $Z\rightarrow b\bar{b}$

abstract:
  We discuss the effect of CP-violating $Zb\bar{b}$, $Zb\bar{b}G$ and
$Zb\bar{b}\gamma$ couplings on the width $\Gamma(Z\rightarrow b\bar bX)$. The
presence of such couplings leads in a natural way to an increase of this width
relative to the prediction of the standard model. Various strategies of a
direct search for such CP-violating couplings by using CP-odd observables are
outlined. The number of $Z$ bosons required to obtain significant information
on the couplings in this way is well within the reach of present LEP
experiments.


title: Heavy Mesons In A Relativistic Model

abstract:
  Motivated by the present interest in the heavy quark effective theory, we use
the spectator equation to treat the mesonic bound states of heavy quarks. The
kernel we use is based on scalar confining and vector Coulomb potentials. Wave
functions are treated to leading order and energies to order $1/m_Q$ in the
heavy-light systems, and order $1/m_Q^2$ in heavy-heavy systems. Our results
are in reasonable agreement with experimental measurements. We estimate two of
the parameters of the heavy quark effective theory, and propose further
calculations that may be undertaken in the future.


title: Scattering from a Domain Wall in a Spontaneously Broken Gauge Theory

abstract:
  We study the interaction of particles with a domain wall at a
symmetry-breaking phase transition by perturbing about the domain wall
solution. We find the particulate excitations appropriate near the domain wall
and relate them to the particles present far from the wall in the uniform
broken and unbroken phases. For a quartic Higgs potential we find analytic
solutions to the equations of motion and derive reflection and transmission
coefficients. We discover several bound states for particles near the wall.
Finally, we apply our results to the electroweak phase transition in the
standard model.


title: $\rho\to 4\pi$ DECAY

abstract:
  The decay modes $\rho^0 \to 2\pi^+ 2\pi^-$ and $\rho^0 \to 2\pi^0 \pi^+
\pi^-$ are considered in the framework of the low energy effective chiral
Lagrangian. The obtained values of the decay widths $\Gamma(\rho^0\to 2 \pi^+ 2
\pi^-)=$ $(16 \pm 1){\rm keV}$ and $\Gamma(\rho^0\to 2 \pi^0 \pi^+ \pi^-)= (6.0
\pm 0.2)$keV do not contradict the existing upper limits and seem to be big
enough for the corresponding processes to be observed in future high luminosity
experiments.


title: Squark Production at the Tevatron

abstract:
  We have determined the QCD corrections to the production of squark-antisquark
pairs in $p\bar p$ collisions at the Tevatron. If the next-to-leading order
corrections are taken into account, the renormalization/factorization scale
dependence of the theoretical prediction for the cross section is reduced
considerably. The higher order corrections increase the production cross
section at the Tevatron by about a factor two if we compare the next-to-leading
order prediction at a scale near the squark mass with the lowest order
prediction for which, in the experimental analyses, the scale was identified
with the invariant energy of the parton subprocess. This results in a rise of
the experimental lower bound on the squark mass from the Tevatron by about $20$
GeV.


title:
QCD Predictions for the Tau Hadronic Width: Determination of
  alpha_s(M_\tau^2)

abstract:
  The total $\tau$ hadronic width can be accurately calculated using
analyticity and the operator product expansion. The theoretical analysis of
this observable is updated to include all available perturbative and
non-perturbative corrections. The experimental determination of
$\alpha_s(M_\tau^2)$ and its actual uncertainties are discussed.


title: The Standard Model of Electroweak Interactions

abstract:
  What follows is an updated version of the lectures given at the CERN Academic
Training (November 1993) and at the Jaca Winter Meeting (February 1994). The
aim is to provide a pedagogical introduction to the Standard Model of
electroweak interactions. After briefly reviewing the empirical considerations
which lead to the construction of the Standard Model Lagrangian, the particle
content, structure and symmetries of the theory are discussed. Special emphasis
is given to the many phenomenological tests (universality, flavour-changing
neutral currents, precision measurements, quark mixing, etc.) which have
established this theoretical framework as the Standard Theory of electroweak
interactions.


title:
$W^+Z$ and $W^+\gamma^*$ Backgrounds to Strong $W^+W^+$ Scattering at
  the LHC

abstract:
  Because of inevitable blind spots at high rapidity and low transverse
momentum, the process $\overline qq \rightarrow l^+ l^- \ l^{+} \nu$ provides a
surprisingly large background to the $W^+W^+ \rightarrow l^+ \nu \ l^+ \nu$
signal associated with strong $WW$ scattering. Previous calculations of the
total background are approximately doubled, and the estimate of the ``no-lose''
luminosity at the LHC to observe manifestations of the electroweak symmetry
breaking mechanism is increased to between $\sim 100$ and $\sim 140$ fb$^{-1}$.


title: Minijet veto: a tool for the heavy Higgs search at the LHC

abstract:
  The distinct color flow of the $qq\to qqH,\; H\to W^+W^-$ process leads to
suppressed radiation of soft gluons in the central region, a feature which is
not shared by major background processes like $t\bar t$ production or $q\bar q
\to W^+W^-$. For the leptonic decay of a heavy Higgs boson, $H\to W^+W^- \to
\ell^+\nu \ell^-\bar\nu$, it is shown that these backgrounds are typically
accompanied by minijet emission in the 20--40 GeV range. A central minijet veto
thus constitutes a powerful background rejection tool. It may be regarded as a
rapidity gap trigger at the semihard parton level which should work even at
high luminosities.


title: Critical Behavior of a Four-Fermion Schwinger-Dyson Equation

abstract:
  We study the Schwinger-Dyson equation associated with a chirality- changing
fermion 4-point function in a strongly-coupled $U(1)$ gauge theory. After
making appropriate simplifications, we solve the equation numerically via a
relaxation method. Our analysis provides an estimate of the critical coupling
and it gives some indication as to the general momentum dependence of the
4-point function.


title: Neutrino Masses

abstract:
  This is a review for Reports of Progress in Physics. After an introduction we
start by explaining the different neutrino masses corresponding to different
types of neutrinos, Dirac or Majorana, in section 2. In section 3 we discuss
the main elementary particle models for neutrino masses and their distinctive
phenomenological consequences. In section 4 we describe the status of direct
mass searches and Majorana mass searches in neutrinoless double beta decays. In
section 5 we go over the many cosmological implications of, and constraints on,
neutrino properties, mainly masses and lifetimes. Sections 6, 7 and 8 review
neutrino oscillations, the solar neutrino problem and the atmospheric neutrino
problem, their implications and the current and future experiments. In
particular, we explain oscillations in vacuum in section 6 and oscillations in
matter in section 7. Section 9 summarizes the main bounds imposed by stars,
mainly SN1987A. A few concluding remarks follow.


title: Lattice QCD

abstract:
  The status of Lattice QCD is reviewed with respect to results that are
relevant to Standard Model phenomenology. I argue that in a few simple cases
all (or almost all) systematic errors from the lattice calculation are under
control. Lattice QCD calculations of quarkonia ($\bb$ and $\cc$) have yielded
precise determinations of the strong coupling, $\alpha_s$, and the heavy quark
masses. Recent work on the kaon $B$ parameter has also led to a significant
reduction in systematic errors, resulting in a precise determination of this
hadronic matrix element. I discuss recent progress in other calculations of
potential phenomenological significance, as well as problems and prospects.


title: Simulations of Supercollider Physics

abstract:
  The Standard Model of particle physics makes it possible to simulate complete
events for physics signatures and their backgrounds in high energy collisions.
Knowledge of how the produced particles interact with the materials in a
detector makes it possible to simulate the response of any particular detector
design to these events and so determine whether the detector could observe the
signal. The combination of these techniques has played an important role in the
design of new detectors, particularly those for hadron supercolliders where the
high rates and small signal cross sections make the experiments very difficult.
The technique is reviewed here and illustrated using the simulations of the GEM
detector proposed for the Superconducting Super Collider. Although the
simulations and results described here are somewhat detector-specific, we
believe that they can serve as a useful model for this component of detector
design for future hadron supercolliders.


title: Low Energy Thresholds and the Renormalization Group in the MSSM

abstract:
  We derive the 1-loop Renormalization Group Equations for the parameters of
the Minimal Supersymmetric Standard Model (MSSM) taking into account the
successive decoupling of each sparticle below its threshold. This is realized
by a step function at the level of each graph contributing to the
Renormalization Group Equations.


title: Novel Pion Electroproduction Low-Energy Theorems

abstract:
  We present novel low--energy theorems for the P--wave multipoles $2M_{1+} +
M_{1-}$, $M_{1+} -M_{1-}$, $E_{1+}$ and $L_{1\pm}$ for neutral pion
electroproduction off protons. These should be very useful for the analysis of
existing or future threshold data.


title:
New Quark Distributions and Semi-Inclusive Electroproduction on
  Polarized Nucleons

abstract:
  The quark-parton model calculation including the effects of intrinsic
transverse momentum and of all six twist-two distribution functions of quarks
in polarized nucleons is performed. It is demonstrated that new twist-two quark
distribution functions and polarized quark fragmentation functions can be
investigated in semi-inclusive DIS at leading order in $Q^2$. The general
expression for the cross-section of semi-inclusive DIS of polarized leptons on
polarized nucleons in terms of structure functions is also discussed.


title: Weak Decays of $B$ Mesons and Lattice QCD

abstract:
  After a pedagogical introduction to the calculation of weak matrix elements
on the lattice, I review some of the lattice's most recent predictions
concerning the weak decays of $B$-mesons. Amongst the topics covered are the
determinations of the leptonic decay constant $f_B$, of the form factors
relevant for semi-leptonic $B\to D(D^*)\ell\bar\nu$ decays and of the hadronic
matrix element which describes the rare decay $B\to K^*\gamma$. Emphasis is
placed on the results of the UKQCD Collaboration. Corrections to the
heavy-quark limit are discussed extensively.


title: Macroscopic Chromodynamics of a Confining Medium

abstract:
  A nonminimal interaction of the gluon field with a massive antisymmetric
tensor order parameter is shown to yield a vanishing dielectric function at
tree level. The London-type description of this perfect diaelectric suggests a
tractable non-Abelian chromodynamics of the Ginzburg-Landau type which is
suitable for describing the confinement-deconfinement phase transition.


title: QED Radiative Corrections for Parton Distributions

abstract:
  I discuss radiative corrections due to the emission of photons from quarks
which contribute to deep inelastic lepton--nucleon scattering as well as to
$pp$ collisions at high energies. These corrections are dominated by quark-mass
singularities which have to be absorbed into the parton distribution functions.
Observable effects appear as a modification of the $Q^2$ dependence of the
distribution functions. Numerical results indicate, however, that these QED
corrections are negligible except at extremely large $Q^2$ and large $x$.
Therefore it is safe to neglect the single and multiple photon effects in $pp$
scattering at LHC energies.


title: Evolution of the spin of the nucleon

abstract:
  We compare momentum sum rules from unpolarized electroproduction and the spin
sum rule for $g_1$ in polarized electroproduction, and their $Q^2$ evolution in
the framework of the operator product expansion. Second order effects in
$\alpha_s$ are included. We show that in comparing the evolution of the spin
sum rule with the momentum sum rule one is not overly sensitive to using first
or second order, even when going to the extreme low $Q^2$ limit in which gluons
carry no momentum. Our results show that in that limit there is no need to
include any contribution of strange quarks.


title:
The Problem of the Double Time-Ordered Operator Product Calculation in
  the Nonequilibrium Quantum Field Theory

abstract:
  It is shown that calculation of the operator's groups product with the
independent time ordering procedure in each one is important for some problems
in the nonequilibrium quantum field theory at finite temperature. This problem
is solved in terms of path integrals by means of time-integration contour
transformation. A role of thermal ghosts for this problem is also discussed.


title:
Angular Distributions of Drell-Yan Lepton Pairs at the Tevatron: Order
  $\alpha_s^2$ Corrections and Monte Carlo Studies

abstract:
  We investigate the angular distribution of the lepton pair in the process $p
\bar{p} \rightarrow \gamma^{\ast} + X \rightarrow \ell^+\ell^- + X$, where the
virtual photon is produced at high transverse momentum. The angular
distribution of the leptons is very sensitive to possible nonperturbative
effects, such as a nontrivial vacuum structure of QCD, and offers a good chance
to test such effects. We present complete ${\cal O}(\alpha_s^2)$ calculations
of the decay lepton distributions in the lepton pair rest frame. An order
${\cal O}(\alpha_s)$ Monte Carlo study of the lepton angular distributions,
with acceptance cuts and energy resolution smearing applied to the leptons, is
also presented.


title: Searching for Relic Neutralinos

abstract:
  Theoretical expectations for direct and indirect searches for relic
neutralinos are presented. Complementarity among various investigation means is
discussed in connection with the values of the neutralino relic abundance.


title: Electroweak corrections to the toponium decay width

abstract:
  We discuss one-loop electroweak corrections to the decay width of toponium.
We calculate the energy-level shifts by expanding around the solution of the
Bethe-Salpeter equation in the instantaneous approximation, in analogy with the
positronium case. We show that first-order electroweak effects are suppressed
by at least four powers of the strong coupling constant, and are therefore
negligible compared with QCD corrections. The calculation is manifestly gauge
invariant and takes into account the contributions to the decay rate due to
both Coulomb enhancement and phase space reduction effects.


title: Threshold production of charmed and B mesons in e+e- annihilation

abstract:
  A simple extension of the QCD inspired potential model which includes
dynamical quarks first proposed by Eichten et al. is remarkably successful in
accounting both for the observed narrow state heavy quarkonium spectroscopy and
experimental data on threshold production of charmed and B mesons in e+e-
annihilation. In addition to this model, a variant of it can also account for
the data. The cross section data are mainly inclusive cross section
measurements. The two models give distinguishably different predictions for the
energy dependence of production cross sections for individual channels, and
measurment of the energy dependence of production cross sections for individual
channels may distinguish between these models.


title: Isgur-Wise Function and $V_{cb}$ from Bethe-Salpeter Equations

abstract:
  We calculate the Isgur-Wise function from the solutions of the Bethe-Salpeter
equations. The shape of the Isgur-Wise function thus calculated is a prediction
of the Bethe-Salpeter equations and does not depend on undetermined parameters.
We develop an analytical approximation to our Isgur-Wise function in the form
$\xi ( \omega) = \eta [ 1 - \frac{{\rho^2}}{\eta} (\omega - 1) + a (\omega -
1)^{3/2}]$ where $\rho^2 = 1.279$, $a = .91$, $\eta = .9942$ and $\omega$ is
the recoil velocity. The Isgur-Wise function is then used to obtain $V_{cb}$
from the recent experimental data of ${\bar B} \to D^* \ell \bar\nu$ decay. Our
best estimate of $V_{cb}$ is $(34.7 \pm 2.5) \times 10^{-3}$, which is
comparable to some of the latest estimates in the literature.


title: Gluon Radiation in t\bar{t} Production at the Tevatron p\bar{p} Collider

abstract:
  We present a complete calculation of the matrix elements for the processes $q
\bar q, gg \to b W^+ \bar b W^- g$ and $qg \to b W^+ \bar b W^- q$ which are
relevant for the study of events with an additional jet in $t \bar t$
production at the Tevatron $p \bar p $ collider. Our calculation includes (i)
the contributions from gluons emitted during the top production and decay
stages and the interference between these, and (ii) the complete set of Feynman
diagrams corresponding to both resonant and non-resonant top production. We
study the distribution in phase space of the additional parton jet and make
comparisons with previous studies based on the soft-gluon approximation and
with results from parton-shower Monte Carlo simulations. The implications for
top mass measurements are briefly discussed.


title: Alpha_s from Tau Decays

abstract:
  We review the present status in the determination of the $accurate$ value of
$\alpha_s$ from $\tau$-decays, where we discuss in detail the different sources
of theoretical errors.


title: A Model Independent Analysis of Solar Neutrino Data

abstract:
  We present the results of a solar model independent analysis of the existing
solar neutrino data in the case of $\nu_{e}\to\nu_{\mu(\tau)}$ MSW transitions.
We considered two cases. In the first case no assumptions on the values of the
total fluxes of neutrinos from all reactions have been made. In the second case
we constrained the values of the neutrino fluxes within some wide limits that
take into account the predictions of the existing Standard Solar Models. We
show that in both cases the existing data allow to exclude rather large regions
in the plane of the parameters $ \Delta m^2 $ and $ \sin^2 2\theta $.


title: Supersymmetric Unification

abstract:
  The measured value of the weak mixing angle is, at present, the only precise
experimental indication for physics beyond the Standard Model. It points in the
direction of Unified Theories with Supersymmetric particles at accessible
energies. We recall the ideas that led to the construction of these theories in
1981.


title:
Dill: An Algorithm and a Symbolic Software Package for Doing Classical
  Supersymmetry Calculations

abstract:
  An algorithm is presented that formalizes different steps in a classical
Supersymmetric (SUSY) calculation. Based on the algorithm Dill, a symbolic
software package, that can perform the calculations, is developed in the
Mathematica programming language. While the algorithm is quite general, the
package is created for the 4-D, N=1 model. Nevertheless, with little
modification, the package could be used for other SUSY models. The package has
been tested and some of the results are presented.


title: Strong Corrections to Inclusive B to X tau nu Decays

abstract:
  We calculate the $\alpha_s$ corrections to the form factors which
parameterize the hadronic tensor relevant for inclusive semileptonic $B
\rightarrow X \tau\bar\nu_{\tau}$ and $\Lambda_b \rightarrow X
\tau\bar\nu_{\tau}$ decays. We apply our results to the double differential
decay rates for the decays of $B$ mesons and polarized $\Lambda_b$ baryons to
polarized $\tau$ leptons, presenting them in terms of one-dimensional
integrals. Formulas appropriate for insertion into a Monte-Carlo simulation are
presented.


title: Probing the Weak Boson Sector in $\gamma e\rightarrow Ze$

abstract:
  We study possible deviations from the standard model in the reaction $\gamma
e\rightarrow Ze$ at a 500 GeV $e^+e^-$ collider. As a photon source we use a
laser backscattered photon beam. We investigate the most general $\gamma
Z\gamma$ and $\gamma ZZ$ vertices including operators up to
energy-dimension-six which are Lorentz invariant. These vertices require four
extra parameters; two are CP-conserving, $h^\gamma_1$ and $h^Z_1$, and two are
CP-violating, $h^\gamma_2$ and $h^Z_2$. We present analytical expressions of
the helicity amplitudes for the process $\gamma e\rightarrow Ze$ for arbitrary
values of anomalous couplings. Assuming Standard Model values are actually
measured we present the allowed region in the ($h^\gamma_1,h^Z_1$) plane at the
90\% confidence level. We then show how the angular correlation of the $Z$
decay products can be used to extract detailed information on the anomalous
(especially CP-violating) $\gamma Z\gamma$ and $\gamma ZZ$ couplings.


title: The Photoproduction of Hybrid Mesons from Cebaf to HERA

abstract:
  Decay widths, branching ratios and production dynamics of some recently
discovered $J^{PC} = 1^{-+}, 0^{-+}$,$1^{--}$ and $2^{-+}$ mesons are found to
be in remarkable agreement with the predicted properties of hybrid mesons. We
propose tests for this new dynamics, emphasise the critical role of $\pi b_1$
or $\pi h_1$ decay channels in discriminating hybrids from conventional states,
and suggest that photoproduction may offer special opportunities for isolation
and confirmation of hybrids.


title: Heavy-Quark Symmetry and Skyrmions

abstract:
  We review recent development on combining heavy-quark symmetry and chiral
symmetry in the skyrmion structure of the baryons containing one or more heavy
quarks, c (charmed) and b (bottom). We describe two approaches: One going from
the chiral symmetry regime of light quarks to the heavy-quark symmetry regime
which will be referred to as ``bottom-up" approach and the other going down
from the heavy-quark limit to the realistic finite-mass regime which will be
referred to as ``top-down." A possible hidden connection between the two
symmetry limits is suggested. This review is based largely on the work done --
some unpublished -- by the authors since several years.


title:
Coherent Bremsstrahlung Emission in the Early Stage of Relativistic
  Heavy Ion Collisions

abstract:
  We present a model of coherent Bremsstrahlung emission from the compression
phase of relativistic heavy ion collisions based on a hydrodynamical
description of the collision process. The decceleration of the matter through a
shock front, calculated in 1-D relativistic dissipative hydrodynamics, is at
the origin of a copious Bremsstrahlung emission. The interferences between the
Bremsstrahlung emitted by two receeding shock fronts result in deviations from
the usual $1/\omega$ law, with in particular a strong suppression of low energy
photons in symmetric collisions. We show how it might be possible to obtain
information on the equation of state, possible transition to a quark gluon
plasma and dynamical properties of the matter from the study of the
interference pattern. We show that the optimal region for the observation of
coherent photons is in SIS - AGS energy range.


title:
New fermions and a vector-like third generation in $SU(3)_c\otimes
  SU(3)_L\otimes U(1)_N$ models

abstract:
  We study two 3-3-1 models with i) five (four) charge 2/3 ($-1/3$) quarks and,
ii) four (five) charge 2/3 ($-1/3$) quarks and a vector-like third generation.
Possibilities beyond these models are also briefly considered.


title:
The renormalization group inspired approaches and estimates of the
  tenth-order corrections to the muon anomaly in QED

abstract:
  We present the estimates of the five-loop QED corrections to the muon anomaly
using the scheme-invariant approaches and demonstrate that they are in good
agreement with the results of exact calculations of the corresponding
tenth-order diagrams supplemented by the additional guess about the values of
the non-calculated contributions.


title:
The High Energy Behavior of the Forward Scattering Parameters \sigma
  total $\rho$, and $B$

abstract:
  Utilizing the most recent experimental data, we reanalyze high energy \pbar p
and pp data, using two distinct (and {\em dissimilar}) analysis techniques: (1)
asymptotic amplitude analysis, under the assumption that we have reached
`asymptopia', and (2) an eikonal model whose amplitudes are designed to mimic
real QCD amplitudes. The former gives strong evidence for a $\log \,(s/s_0)$
dependence at {\em current} energies and {\em not} $\log^2 (s/s_0)$, and
demonstrates that odderons are {\em not} necessary to explain the experimental
data. The latter gives a unitary model for extrapolation into true `asymptopia'
from current energies, allowing us to predict the values of the total cross
section at future supercolliders. Using our QCD-model, we obtain $\stot(16\,\,
{\rm TeV})=109\pm4$\,mb and $\stot(40\,\, {\rm TeV})=124\pm4$\,mb.


title: The b->s +\gamma Decay in Supergravity

abstract:
  The $b\rightarrow s+ \gamma$ decay is a powerful tool for testing models of
new physics because the new physics diagrams enter in the same loop order as
the Standard Model ones. The current experimental and theoretical status of
this decay is reviewed. Predictions based on the minimal supergravity model
(MSGM) in the leading order (LO) are discussed. It is shown that results are
sensitive to the value of $m_{t}$ and $\alpha_{G}$. The current experimental
value for the $b\rightarrow s + \gamma$ rate already very likely eliminates
part of the SUSY parameter space when both $m_{o}$ and $m_{\tilde{g}}$ are
small and when $A_{t}$ and $\mu$ have the same sign. Dark matter detection
rates for $\tilde{Z}_{1}$ cold dark matter for $\mu <0$ are only minimally
affected by the current data, as are proton decay predictions for models
consistent with current proton lifetime and $\tilde{Z}_{1}$ relic density
bounds. [\dag Invited talk at ``Physics From Planck Scale to Electroweak
Scale'', Warsaw, Sept. 21-24, 1994].


title: A Test of the Standard Model, Using Da$\Phi$ne

abstract:
  Both the light hypernucleus ${}_\Lambda {\rm H}^4$ and the nucleus ${\rm
He}^4$ have spin 0. The ratio $R$ of the electron to muon rates for the pure
Fermi transitions \begin{equation} R=\frac{\Gamma\left({}_\Lambda {\rm
H}^4\rightarrow {\rm e}^- + \bar \nu +{\rm He}^4\right)}
{\Gamma\left({}_\Lambda {\rm H}^4\rightarrow {\mu}^- + \bar \nu +{\rm
He}^4\right)} \end{equation} is a sensitive measure of the presence of a {\em
second-class} weak current (to the extent that SU(3) is valid in strong
interactions), and hence, is a test of the Standard Model. Rates and
sensitivities, using Da$\Phi$ne, the $e^+e^-$ machine under construction at
Frascati, are discussed.


title: Limits on the Ununified Standard Model

abstract:
  The ununified standard model is an extension of the standard model that
contains separate electroweak gauge groups for quarks and leptons. When it was
originally proposed, data allowed the new gauge bosons to be quite light. We
use recent data from precision electroweak measurements to put stringent bounds
on the ununified standard model. In particular, at the 95% confidence level, we
find that the ununified gauge bosons must have masses above about 2 TeV.


title:
Q^2-Evolution of Nucleon's Chiral-Odd Twist-3 Structure Function:
  h_L(x,Q^2)

abstract:
  We investigate the $Q^{2}$-evolution of the chiral-odd spin-dependent parton
distribution $h_{L}(x, Q^{2})$ relevant for the polarized Drell-Yan processes.
The results are obtained in the leading logarithmic order in the framework of
the renormalization group and the standard QCD perturbation theory. We
calculate the anomalous dimension matrix for the twist-3 operators for $h_{L}$
in the one-loop order. The operator mixing among the relevant twist-3 operators
including the operators proportional to the QCD equations of motion is treated
properly in a consistent scheme. Implications for future experiments are also
discussed.


title:
Two-loop ${\rm O}\left(G_F^2M_H^4\right)$ corrections to the fermionic
  decay rates of the Higgs boson

abstract:
  We calculate the dominant ${\rm O}\left(G_F^2M_H^4\right)$ two-loop
electroweak corrections to the fermi\-onic decay widths of a heavy Higgs boson
in the Standard Model. Use of the Goldstone-boson equivalence theorem reduces
the problem to one involving only the physical Higgs boson $H$ and the
Goldstone bosons $w^\pm$ and $z$ of the unbroken theory. The two-loop
corrections are opposite in sign to the one-loop electroweak corrections,
exceed the one-loop corrections in magnitude for $M_H>1114\ {\rm GeV}$, and
increase in relative magnitude as $M_H^2$ for larger values of $M_H$. We
conclude that the perturbation expansion in powers of $G_FM_H^2$ breaks down
for $M_H\approx 1100\ {\rm GeV}$. We discuss briefly the QCD and the complete
one-loop electroweak corrections to $H\rightarrow b\bar{b}, \,t\bar{t}$, and
comment on the validity of the equivalence theorem. Finally we note how a very
heavy Higgs boson could be described in a phenomenological manner.


title: Suppression of dilepton production in hot hadronic matter

abstract:
  The pion electromagnetic form factor at finite temperature is studied using
an effective chiral lagrangian that includes explicitly vector mesons. We find
that in the time-like region around the rho meson resonance it decreases with
increasing temperature and leads to a suppression of dilepton production from
pion-pion annihilation in a hot hadronic matter. Effects on dilepton production
in high energy heavy ion collisions and its relevance to the phase transition
in a hot hadronic matter are discussed.


title: Spin effects in strong interactions at high energy

abstract:
  Spin effects in strong interaction high energy processes are subtle phenomena
which involve both short and long distance physics and test perturbative and
non perturbative aspects of QCD. Moreover, depending on quantities like
interferences between different amplitudes and relative phases, spin
observables always test a theory at a fundamental quantum mechanical level; it
is then no surprise that spin data are often difficult to accomodate within the
existing models. A report is made on the main issues and contributions
discussed in the parallel Session on the ``Strong interactions at high energy"
in this Conference.


title: QCD_{1+1} at large N_F and N_C

abstract:
  QCD in 1+1 dimensions is examined in the limit of a large number of colors
and flavors. The Hamiltonian matrix is given in a Fock space spanned by 't
Hooft meson states and, for the case of zero fermion mass, a submatrix is
diagonalized numerically to give the low-lying spectrum as a function of $N_F
/N_C $. Pair creation effects generate bound states which are complicated
mixtures of components of different meson number. There are a number of
nontrivial zero modes; in the massive part of the spectrum some states tend to
a well-defined $N_F \gg N_C $ limit while others become unstable and disappear.
The masses of most states remain remarkably constant over a large range of $N_F
/N_C $.


title: Equivalence of Light-Front and Covariant Field Theory

abstract:
  In this paper we discuss the relation between the standard covariant quantum
field theory and light-front field theory. We define covariant theory by its
Feynman diagrams, whereas light-front field theory is defined in terms of
light-cone time-ordered diagrams. A general algorithm is proposed that produces
the latter from any Feynman diagram. The procedure is illustrated in several
cases. Technical problems that occur in the light-front formulation and have no
counterpart in the covariant formulation are identified and solved.


title: Physics of Strangelets

abstract:
  After a brief introduction to the physics of bulk strange quark matter (SQM)
this review focuses on the properties of low baryon number strangelets
presently searched for in ultra-relativistic heavy-ion experiments at CERN and
Brookhaven. Shell-model calculations reveal interesting (meta)stability
properties in the experimentally accessible regime. A liquid drop model
(Fermi-gas model) is shown to explain the overall behavior of the mode-filling
calculations, leading to a physical understanding of strangelet properties,
which can be generalized to non-zero temperature and pressure.


title:
The electroweak chiral Lagrangian as an effective field theory of the
  standard model with a heavy Higgs

abstract:
  Using effective field theory methods, we integrate out the standard model
Higgs boson to one loop and represent its non-decoupling effects by a set of
gauge invariant effective operators of the electroweak chiral Lagrangian. We
briefly discuss the relation between the renormalization of both the standard
model and the effective theory, which is crucial for a correct understanding
and use of the electroweak chiral Lagrangian. Some examples have been chosen to
show the applicability of this effective Lagrangian approach in the calculation
of low energy observables in electroweak theory.


title: Baryon masses from QCD current correlators at $T\neq 0$

abstract:
  Correlation functions of QCD currents with quantum numbers of nucleon and
$\Delta$-isobar are considered at finite temperatures. Corrections of order
$T^4$ to the correlators are calculated and interpreted in terms of thermal
mass shifts using a QCD sum rules type of argument. In both cases the masses
decrease with $T$.


title: Universality of the Pinch Technique Gauge Boson Self-Energies

abstract:
  It is shown how the S-matrix pinch technique may be extended to the cases of
external scalar and gauge boson fields. Using this extension, the universality
of the pinch technique gauge-independent one-loop gauge boson self-energy in a
general unbroken SU($N$) gauge theory is demonstrated explicitly.


title: Absence of Species Doubling in Finite-Element Quantum Electrodynamics

abstract:
  In this letter it will be demonstrated explicitly that the finite-element
formulation of quantum electrodynamics is free from fermion doubling. We do
this by (1) examining the lattice fermion propagator and using it to compute
the one-loop vacuum polarization on the lattice, and (2) by an explict
computation of vector and axial-vector current anomalies for an arbitrary
rectangular lattice in the Schwinger model. There it is shown that requiring
that the vector current be conserved necessitates the use of a square lattice,
in which case the axial-vector current is anomalous.


title: On the interaction of spin 3/2 particles

abstract:
  Lagrangian of a massive particle with spin 3/2 is considered in the
Rarita-Schwinger formalism. We discuss implications of the contact- and the
gauge-transformation on the physical content of free and interacting theories.
It is shown that the ``contact-invariance'' is trivial and has no physical
relevance. The requirement of the gauge-invariance of the free lagrangian fixes
the off-shell lower-spin content of the spin-3/2 field. The gauge-invariance of
the interaction lagrangian insures that these lower-spin components are not
coupled, and (probably always) leads to theories consistent with local
causality.


title:
Naturalness and superpartner masses or when to give up on weak scale
  supersymmetry

abstract:
  Superpartner masses cannot be arbitrarily heavy if supersymmetric extensions
of the standard model explain the stability of the gauge hierarchy. This
ancient and hallowed motivation for weak scale supersymmetry is often quoted,
yet no reliable determination of this upper limit on superpartner masses
exists. In this paper we compute upper bounds on superpartner masses in the
minimal supersymmetric model, and we identify which values of the superpartner
masses correspond to the most natural explanation of the hierarchy stability.
We compare the most natural value of these masses and their upper limits to the
physics reach of current and future colliders. As a result, we find that
supersymmetry could explain weak scale stability naturally even if no
superpartners are discovered at LEP II or the Tevatron (even with the Main
Injector upgrade). However, we find that supersymmetry cannot provide a
complete explanation of weak scale stability, if squarks and gluinos have
masses beyond the physics reach of the LHC. Moreover, in the most natural
scenarios, many sparticles, for example, charginos, squarks, and gluinos, lie
within the physics reach of either LEP II or the Tevatron. Our analysis
determines the most natural value of the chargino (squark) ((gluino)) mass
consistent with current experimental constraints is $\sim$ 50 (250) ((250)) GeV
and the corresponding theoretical upper bound is $\sim$ 250 (700) ((800)) GeV.


title: Rapidity-Dependent Low-pt Enhancement

abstract:
  The rapidity dependence of the low-$p_t$ enhancement is shown to be a
sensitive measure of the longitudinal source size for longitudinally expanding
finite systems.


title:
Constraints on Form Factors For Exclusive Semileptonic Heavy to Light
  Meson Decays

abstract:
  We use rigorous QCD dispersion relations to derive model-independent bounds
on the B -> pi l nu, D -> pi l nu and D -> K l nu form factors. These bounds
are particularly restrictive when the value of the observable form factor at
one or more kinematic points is assumed. With reasonable assumptions we find
f_B < 195 MeV and that the shape of the form factor becomes severely
constrained. These constraints are useful both for model discrimination and for
model-insensitive extraction of CKM mixing parameters.


title: The Two Loop Long Range Effect on the Proton Decay Effective Lagrangian

abstract:
  We calculate the two loop long range effect on the proton decay effective
Lagrangian. Numerical calculation for suppression factor gives $ A_L($2-loop$)
= 0.321$ for the value of the strong coupling constant $ \alpha_s(m_Z) = 0.116
$. Two loop effect to more general effective Lagrangian is also given.


title: Strong Interactions at Low Energy

abstract:
  This is a revised version of a talk given at the Chiral Dynamics Workshop at
M.I.T., July 25, 1994. It reports results in three areas: (1) The
isospin-violating interactions between one non-relativistic nucleon and any
number of soft pions can be summarized in a single term in the effective chiral
Lagrangian, with no unknown parameters. (2) With D'Hoker, it has been shown
that the terms in the Lagrangian for an effective field theory with symmetry
$G$ spontaneously broken to $H$, that are not the integrals of $G$-invariant
Lagrangian densities, are in one-to-one correspondence with the generators of
$H_5(G/H,R)$. (3) If we assume that the nucleon is connected by successive
one-pion transitions only to a tower of narrow baryon states with
$T=J=1/2,3/2,\dots,N_c/2$, then the Adler-Weisberger and superconvergence
relations tell us (for any $N_c$) that (a) the tower states are degenerate, and
(b) the one-pion transition amplitudes between these states generate the {\em
uncontracted} algebra of $SU(4)\times O(3)$.


title:
QCD coherence in the structure function and associated distributions at
  small $x$

abstract:
  We recall the origin of angular ordering of soft parton emission in the
region of small $x$ and show that this coherent structure can be detected in
associated distributions. For structure functions at small $x$ and at fixed
transverse momentum the angular ordering is masked because of the complete
inclusive cancellations of collinear singularities for \xt0. Therefore, in this
case the dependence on the hard scale is lost and the angular ordered region
becomes equivalent to multi-Regge region in which all transverse momenta are of
the same order. In this limit one derives the BFKL equation. In general such a
complete cancellation does not hold for the associated distributions at small
$x$. The calculation, which requires an analysis without any collinear
approximation, is done by extending to small $x$ the soft gluon factorization
techniques largely uses in the region of large $x$. Since one finds angular
ordering in the both regions of small and large $x$, one can formulate a
unified evolution equation for the structure function, a unified coherent
branching and jet algorithm which allows the calculation of associated
distributions in all $x$ regions. Such a unified formulation valid for all $x$
is presented and compared with usual treatments. In particular we show that the
associated distributions at small $x$ are sensitive to coherence. By replacing
angular ordering with the multi-Regge region one neglects large singular
contributions in the associated distributions.


title: Deconfinement of Constituent Quarks and the Hagedorn Temperature

abstract:
  The double phase transition of hadronic matter, $H$, first, to the gas of
deconfined constituent quarks (for brevity called {\it valons}), $Q$, and then,
secondly, the phase transition from $Q$ to quark-gluon plasma, $QGP$, is
considered within bag model ideology. In distinction from previous double phase
transition investigations, it is not supposed that at zero chemical potential
(~$\mu=0$~) transition temperatures $T_d$ (for $H~\leftrightarrow~Q$) and
$T_{ch}$ (for $Q~\leftrightarrow~ QGP$, chiral restoration) coincide. Then for
plausible range of chosen bag constants, $B_Q$ for $Q$ and $B_q$ for $QGP$ the
phase transition $H~ \leftrightarrow~ QGP$ can proceed {\it only via the $Q$
phase} (at least at not too much $\mu$). For small $\mu$ the gap,
$T_{ch}~-~T_d$, is quite essential, up to $\approx~50$ MeV. The physical
meaning of the $H~ \leftrightarrow~ Q$ transition temperature, $T_d$, coincide
with that of the Hagedorn temperature, $T_H$.


title:
Like-sign dilepton signature for gluino production at LHC including top
  quark and higgs boson effects

abstract:
  A systematic analysis of the like-sign dipleton signature for gluino
production at LHC is performed in the $R$-conserving minimal supersymmetric
standard model, taking into account the top quark and Higgs boson effects in
the cascade decay. We consider two representative values of the gluino mass,
300 and 800 GeV, along with those of the other SUSY parameters. While the top
quark contribution is kinematically suppressed for the former case it is very
import for the latter. Ways of separating the signal from the background are
discussed. One expects a viable LSD signals upto a gluino mass of $\sim 800$
(1200) GeV at the low (high) luminosity option of LHC over practically the full
parameter space of MSSM.


title: Baryogenesis and damping in nonminimal electroweak models

abstract:
  We study the effect of damping on the generation of baryon asymmetry of the
Universe in the standard model of the eletroweak theory with simple extensions
of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are
considered, taking into account their markedly different dispersion relations
due to interaction with the hot electroweak plasma. It is argued that the
contribution of the b quark can be comparable to that of the t quark calculated
earlier.


title:
Adiabatic matter effect with three generation neutrinos and the solar
  neutrino problem

abstract:
  We find an exact analytic solution for the time evolution of a three Dirac
neutrino system adiabatically oscillating in matter, constructing explicitly
the relevant $3\times 3$ mixing matrix in matter. Using this result we
investigate the solar neutrino data in a scenario where the neutrino masses are
such that $m_1\alt m_2\ll m_3$, taking into account several phenomenological
constraints on neutrino mixing angles and masses. A solution of the solar
neutrino problem for large values of the parameter $\delta m^2=m_2^2-m_1^2$
which are not usually associated with a resonance is found. This is an
essentially three-generation effect.


title: String no-scale supergravity

abstract:
  We explore the postulates of string no-scale supergravity in the context of
free-fermionic string models. The requirements of vanishing vacuum energy, flat
directions of the scalar potential, and stable no-scale mechanism impose strong
restrictions on possible string no-scale models, which must possess only two or
three moduli, and a constrained massless spectrum. The
soft-supersymmetry-breaking parameters involving all twisted and untwisted
fields are given explicitly. This class of models contain no free parameters,
\ie, in principle all supersymmetric particle masses and interactions are
completely determined. A computerized search for free-fermionic models with the
desired properties yields a candidate $SU(5)\times U(1)$ model containing extra
(\r{10},\rb{10}) matter representations that allow gauge coupling unification
at the string scale. Our candidate model possesses a bening non-universal
assignment of supersymmetry breaking scalar masses, which may have interesting
low-energy experimental consequences.


title: Test of universality hypothesis for scalar potential between quarks

abstract:
  The universality hypothesis for scalar confining potential between quark and
antiquark with different flavours is confirmed within 0.05 level of relativity
errors.


title:
Abundant phi-Meson Production in pbar-p Annihilation at Rest and
  Strangeness in the Nucleon

abstract:
  A large apparent violation of the OZI rule has recently been found in many
channels in pbar-p annihilation LEAR. An interpretation of these data in terms
of the "shake-out" and "rearrangement" of an intrinsic sbar-s component of the
nucleon wave function is proposed. This gives a channel-dependent,
non-universal modification of the naive OZI prediction. Within this approach,
we interpret the strong excess of $\phi$ production in S-wave pbar-p
annihilations in terms of the polarization of the nucleon's sbar-s component
indicated by deep inelastic lepton-nucleon scattering experiments. This
interpretation could be tested by measurements of the $f_2'(1525)/f_2(1270)$
production ratio in P-wave annihilations and by experiments with polarized
beams and polarized targets. We also propose a test of the intrinsic
strangeness hypothesis in $\phi$ production in high-momentum transfer
processes, via a difference in constituent counting rules from gluon-mediated
production.


title: Nonperturbative Corrections to the Dilepton Cross Section

abstract:
  We study the sensitivity of the dilepton production cross section to higher
twist terms. A method for calculating the resummed cross section is introduced
in moment space, where the leading higher twist terms can be easily
parametrized and calculated. We find that a $1/Q$ power correction may
significantly affect the cross section at fixed-target energies.


title:
On dynamics of pseudorapidity fluctuations in central C--Cu collisions
  at 4.5~A GeV/c

abstract:
  Results on dynamical fluctuations of charged particles in the pseudorapidity
space of central C--Cu interactions at 4.5 $A$ GeV/$c$ are performed in the
transformed variables and using higher order scaled factorial moments modifyied
to remove the bias of infinite statistics in the normalization. The
intermittency behavior is found up to eighth order of the moments increasing
with the order and leading to the pronounced multifractality. Two differed
intermittent-like rises are obtained, one indicating an occurrence of the
non-thermal phase transition, and no critical behavior is found to be reached
in another case. The observations may be treated to show different regimes of
particle production during the cascade. Comparison with some conventional model
approximations notes the multiparticle character of the fluctuations. The
results presented can be effective in sense of sensitivity of intermittency to
the hadronization phase.


title: HQQET: An Effective Theory Approach to Heavy Quarkonia Decays

abstract:
  We discuss systems containing a heavy quark and a heavy antiquark in the
infinite mass limit of QCD. Studying the limit of equal velocities for both
heavy particles, we formulate an effective theory approach to heavy
quarkonia-like systems. The method is well suited to processes in which the two
heavy quarks annihilate, such as electromagnetic and strong decays of
charmonium and bottomonium and weak decays of $B_c$.


title: The Inclusive Two Jet Triply Differential Cross Section

abstract:
  We study the inclusive two jet triply differential cross section
$d^3\sigma/dE_Td\eta_1d\eta_2$ at Fermilab energies. Different $\eta_1$ and
$\eta_2$ pseudorapidity regions are directly related to both the parton level
matrix elements and the parton densities at leading order. We present the
next-to-leading order [${\cal O}(\alpha_s^3)$] corrections and show that the
shape of the distribution at fixed transverse energy $E_T$ is a particularly
powerful tool for constraining the parton distributions at small to moderate
$x$ values. We investigate the renormalisation/factorisation scale uncertainty
present in the normalisation and shape of the distribution at next-to-leading
order. We discuss specific slices of the distribution, the same-side/opposite
side ratio and the signed pseudorapidity distribution, in detail and compare
them with preliminary experimental data.


title: Summary of $\pi$--$\pi$ Scattering Experiments

abstract:
  Present status of the study of the low energy $\pi\pi$ interaction is
reviewed, including the recent results on reactions $\pi N \to\pi\pi N$ near
threshold. Current experimental values of s-wave $\pi\pi$ scattering lengths
are compared with predictions of various theoretical models. Required
experimental and theoretical improvements are discussed, in particular the need
for a new $K_{e4}$ decay measurement, and a more reliable theoretical
interpretation of the near-threshold $\pi N \to\pi\pi N$ data.


title: Applicability of Perturbative QCD to $B\to D$ Decays

abstract:
  We examine the applicability of perturbative QCD to $B$ meson decays into $D$
mesons. We find that the perturbative QCD formalism, which includes Sudakov
effects at intermediate energy scales, is applicable to the semi-leptonic decay
$B\to D l\nu$, when the $D$ meson recoils fast. Following this conclusion, we
analyze the two-body non-leptonic decays $B\to D\pi$ and $B\to DD_s$. By
comparing our predictions with experimental data, we extract the matrix element
$|V_{cb}|=0.044$.


title: Numerical Solution of Altarelli-Parisi Equations

abstract:
  We discuss numerical solution of Altarelli-Parisi equations in a
Laguerre-polynomial method and in a brute-force method. In the Laguerre method,
we get good accuracy by taking about twenty Laguerre polynomials in the
flavor-nonsinglet case. Excellent evolution results are obtained in the singlet
case by taking only ten Laguerre polynomials. The accuracy becomes slightly
worse in the small and large $x$ regions, especially in the nonsinglet case.
These problems could be implemented by using the brute-force method; however,
running CPU time could be significantly longer than the one in the Laguerre
method.


title:
Triply Differential Jet Cross Sections for Hadron Collisions at Order
  alpha_s^3 in QCD

abstract:
  We discuss cross sections for hadron + hadron to 2 jets + anything in which
three jet variables are measured. Such cross sections are useful especially for
determining parton distributions. We define a new cross section d sigma/dX_A
dX_B d eta_* for which the perturbation theory is nicely behaved even in the
kinematic regime where the parton distributions are probed at large momentum
fractions. The cross section d\sigma/dE_{T1}\, d\eta_1\, d\eta_2, which has
been used in the past, is not so well behaved in this region. We calculate
these cross sections at order $\alpha_s^3$ in QCD.


title: On the large-$N_c$ behavior of the $L_7$ coupling in $\chi$PT

abstract:
  It is shown that the usual large-$N_c$ counting of the coupling constant
$L_{7}$ of the ${\cal O}(p^4)$ low-energy chiral $SU(3)$ Lagrangian \cite{GL85}
is in conflict with general properties of QCD in the large-$N_c$ limit. The
solution of this conflict within the framework of a chiral $U(3)$ Lagrangian is
explained.


title: Quantum coherence in heavy-flavor production on nuclei

abstract:
  We describe a light-cone wave function formalism for hadroproduction of
heavy-flavors via gluon-gluon fusion. The developed approach is well suited to
address coherence effects in heavy-quark production on nuclei at small $x_{2}
\lsim 0.1\cdot A^{-1/3}$. Nuclear attenuation in hadroproduction of
heavy-flavors is found to be similar to shadowing effects for heavy-flavor
structure functions in deep-inelastic scattering from nuclei. Nevertheless,
remaining differences in the theoretical formulation of both processes imply
corrections to factorization theorems.


title: Renormalons at Low x

abstract:
  The role of infrared and ultraviolet renormalons are discussed in context of
leading log(1/x) approximation of perturbative QCD. We generalize the BFKL
equation for the case of running coupling QCD constant and show that the
uncertainties related to the contribution of infrared renormalons turn out to
be smaller than the shadowing correction to the total cross section. The
contribution of infrared and ultraviolet renormalons to the BFKL equation are
studied, and the solution of the BFKL equation with running coupling constant
is discussed.


title: Supersymmetry dileptons and trileptons at the Tevatron

abstract:
  We consider the production of supersymmetry neutralinos and charginos in
$p\bar p$ collisions at the Tevatron, and their subsequent decay via
hadronically quiet dileptons and trileptons. We perform our computations in the
context of a variety of supergravity models, including generic four-parameter
supergravity models, the minimal $SU(5)$ supergravity model, and $SU(5)\times
U(1)$ supergravity with string inspired two- and one-parameter moduli and
dilaton scenarios. Our results are contrasted with estimated experimental
sensitivities for dileptons and trileptons for integrated luminosities of
$100\ipb$ and $1\ifb$, which should be available in the short and long terms.
We find that the dilepton mode is a needed complement to the trilepton signal
when the latter is suppressed by small neutralino leptonic branching ratios.
The estimated reaches in chargino masses can be as large as $100\,(150)\GeV$
for $100\ipb\,(1\ifb)$. We also discuss the task left for LEPII once the
Tevatron has completed its short-term search for dilepton and trilepton
production.


title:
The effect of the vertical part of the path on the real time Feynman
  rules in finite temperature field theory

abstract:
  The effect of the contribution of the vertical part of the real time path is
studied completely in the case of two points functions. Indeed, this vertical
part generally contributes in the calculation of a given graph. Moreover, this
contribution is essential in order to have a consistent equilibrium theory:
thanks to this contribution, the Green function are effectively invariant by
time translation, as they should be. As a by product, it is shown that the
perturbative calculations give a result which does not depend on the initial
time $t_I$ and final time $t_F$ of the path. The property of independence with
respect to $t_I$ is closely related to the KMS conditions, i.e. to the fact the
system is in thermal equilibrium. In the case of two point functions, the
contribution of the vertical part can be taken into account by the $n(|k_0|)$
prescription in the usual RTF Feynman rules.


title: Total Cross Sections for Heavy Flavour Production at HERA

abstract:
  We compute total cross sections for charm and bottom photoproduction at HERA
energies, and discuss the relevant theoretical uncertainties. In particular we
discuss the problems arising from the small-$x$ region, the uncertainties in
the gluon parton density, and the uncertainties in the hadronic component of
the cross section. Total electroproduction cross sections, calculated in the
Weizs\"acker-Williams approximation, are also given.


title:
Correction Factors for Reactions involving Quark-Antiquark Annihilation
  or Production

abstract:
  In reactions with $q \bar q$ production or $q\bar q$ annihilation, initial-
and final-state interactions give rise to large corrections to the lowest-order
cross sections. We evaluate the correction factor first for low relative
kinetic energies by studying the distortion of the relative wave function. We
then follow the procedure of Schwinger to interpolate this result with the
well-known perturbative QCD vertex correction factors at high energies, to
obtain an explicit semi-empirical correction factor applicable to the whole
range of energies. The correction factor predicts an enhancement for $q\bar q$
in color-singlet states and a suppression for color-octet states, the effect
increasing as the relative velocity decreases. Consequences on dilepton
production in the quark-gluon plasma, the Drell-Yan process, and heavy quark
production processes are discussed.


title: Use of Recursion Relations to Compute One-Loop Helicity Amplitudes

abstract:
  We illustrate the use of recursion relations in the computation of certain
one-loop helicity amplitudes containing an arbitrary number of gauge bosons.
After a brief review of the recursion relations themselves, we discuss the
resolution of the apparent conflict between the spinor helicity method used to
solve the recursion relations and the dimensional regulator used in the loop
integrals. We then outline the procedure for constructing loop amplitudes, and
present two examples of results obtained in this manner.


title: Heavy Baryons: Current, Pion and Photon Transtions

abstract:
  We discuss the structure of current-induced bottom baryon to charm baryon
transitions, and the structure of pion and photon transitions between heavy
charm or bottom baryons in the Heavy Quark Symmetry limit as ${\scriptstyle
m_Q\rightarrow \infty}$. Our discussion involves the ground state $s$-wave
heavy baryons as well as the excited $p$-wave heavy baryon states.


title: Open Charm Production in an Equilibrating Parton Plasma

abstract:
  Open charm production during the equilibration of a gluon dominated parton
plasma is calculated, with both the time-dependent temperature and parton
densities given by a set of rate equations. Including pre-thermal production,
the total enhancement of open charm production over the initial gluon fusion
depends sensitively on the initial parton density and the effective
temperature. The dependence of the pre-thermal charm production on the
space-momentum correlation in the initial parton phase-space distribution is
also discussed.


title:
$1/N_c$ Rotational Corrections to $g_A$ in the NJL Model and Charge
  Conjugation

abstract:
  We show that the $1/N_c$ rotational corrections to $g_A$, derived using the
semiclassical quantization scheme in the NJL model, possess correct properties
under charge conjugation.


title: Baryon Chiral Perturbation Theory up to Next-to-Leading Order

abstract:
  We examine the general lagrangian for baryon chiral perturbation theory with
SU(3) flavor symmetry, up to the next-to-leading order. We consider both the
strong and the weak interaction. The inverse of the baryon mass is treated as
an additional small expansion parameter, and heavy fermion effective field
theory techniques are employed to provide a consistent expansion scheme. A
detailed account is given on the restrictions imposed on the lagrangian by the
various symmetries. Corrections due to the finite baryon mass are also
discussed.


title: Weak Decays of Heavy Mesons in the Instantaneous Bethe Salpeter Approach

abstract:
  In the framework of the instantaneous Bethe Salpeter equation we investigate
weak decays of B and D mesons. Mesons are described as q-bar q states
interacting via a mixture of a scalar and a vector confining kernel and a one
gluon exchange. The model parameters are fixed by a fit to the meson mass
spectrum including also the light mesons. We calculate form factors and compare
our results to the pole dominance hypothesis. From a fit to ARGUS and CLEO data
on B -> D* semileptonic decay we extract the Cabbibo Kobayashi Maskawa matrix
element to be V_cb= (0.032+-0.003)*sqrt(1.49ps/tau_B). The Isgur Wise function
is calculated utilizing the heavy quark mass limit. Finally, we give some
results on non-leptonic decays.


title: Two-loop three-point diagrams with irreducible numerators

abstract:
  We study the problem of calculating two-loop three-point diagrams with
irreducible numerators (i.e. numerators which cannot be expressed in terms of
the denominators). For the case of massless internal particles and arbitrary
(off-shell) external momenta, exact results are obtained in terms of
polylogarithms. We also consider the tensor decomposition of two-loop
three-point diagrams, and show how it is connected with irreducible numerators.


title:
Schwinger Particle-Production Mechanism for a Finite-Length Flux Tube
  with Transverse Confinement

abstract:
  Previous results for the pair production probability in a strong electric
field with a finite longitudinal separation are generalized to the case of a
finite-length flux tube with transverse confinement. The threshold length of
the flux tube, below which pair production cannot occur, increases as a result
of transverse confinement.


title: The Worldline Path Integral Approach to Feynman Graphs

abstract:
  The worldline path integral approach to the Bern-Kosower formalism is
reviewed, which offers an alternative to Feynman diagram calculations in
quantum field theory. Recent progress in constructing a multiloop
generalization of this formalism is reported.


title: Boson Interferometry after SPS and before RHIC

abstract:
  We re--examine the connection between interferometry and the Wigner
representation for source freeze--out, and continuous emission. At the operator
level, two equivalent representations of the two--particle spectrum are found,
which contradict the standard expression of kinetic theory. The discrepancy is
resolved using two toy models. Further, we revisit interferometry in
scale--invariant one--dimensional hydrodynamics, and argue that recent
experimental results are evidence for a short kaon emission time. Using two
exactly calculable models of two-- and three--dimensional flow, it is shown
that the saddle point approximation, which is reasonable for one--dimensional
flow, is no longer adequate. In these models the scaling law is altered, and we
argue that such qualitative trends, together with other observables, are vital
if one is to draw conclusions about the unknown source parameters.


title:
Hydrodynamics near the QCD Phase Transition: Looking for the
  Longest-Lived Fireball

abstract:
  We propose a new strategy for the experimental search of the QCD phase
transition in heavy ion collisions: One may tune collision energy around the
point where the lifetime of the fireball is expected to be longest. We
demonstrate that the hydrodynamic evolution of excited nuclear matter does
change dramatically as the initial energy density goes through the "softest
point" (where the pressure to energy density ratio reaches its minimum). For
our choice of equation of state, this corresponds to epsilon_i approx. = 1.5
GeV/fm^3 and collision energy E_lab/A approx. = 30 GeV (for Au+Au). Various
observables seem to show distinct changes near the softest point.


title: Tests of the Standard Model and Searches for New Physics

abstract:
  The implications of precision $Z$ and $W$-pole and neutral current data for
testing the standard electroweak model, determining its parameters, and
searching for new physics, are described.


title: Quantum Field Kinetics

abstract:
  Using the general framework of quantum field theory, we derive basic
equations of quantum field kinetics. The main goal of this approach is to
compute the observables associated with a quark-gluon plasma at different
stages of its evolution. We start by rewriting the integral equations for the
field correlators in different forms, depending on the relevant dynamical
features at each different stage. Next, two versions of perturbation expansion
are considered. The first is best suited for the calculation of electromagnetic
emission from chaotic, but not equilibrated, strongly interacting matter. The
second version allows one to derive evolution equations, which are
generalizations of the familiar QCD evolution equations, and provide a basis
for the calculation of the initial quark and gluon distributions after the
first hard interaction of the heavy ions.


title:
Quark and gluon distributions at the earliest stage of heavy ion
  collision

abstract:
  Using the general framework of quantum field kinetics we consider new
principles to compute initial distribution of quarks and gluons after the first
hard interaction of heavy ions. We start by rewriting the integral equations of
QCD in the form which is generalizations of the familiar QCD evolution
equations. These equations describe both space-time-- and $(x,Q^2)$--evolution
before the collision, and allow one to use the $ep$ DIS data without reference
to parton phenomenology. New technique generate perturbation theory that avoid
double count of the processes, does not contain an artificial factorization
scale, and does not require low-momentum cut-offs since infrared behavior is
controlled by the DIS data.


title: Study of Chiral Invariance Using Pions

abstract:
  We review two manifestations of chiral symmetry breaking in the pion sector.
First, we examine the $\pi\pi$ scattering amplitude at threshold, which is
completely determined by the chiral symmetry breaking part of the strong
interaction, and, thus, directly constrains the form of the low energy
effective lagrangians. We review the current status of the $\pi\pi$ scattering
lengths in view of the recent results on reactions $\pi N \to\pi\pi N$ near
threshold, and discuss the needed improvements. Second, we focus on the rate of
the pion beta decay, determined at the tree level by the CVC hypothesis, a
remnant of chiral symmetry breaking. Precise knowledge of the $\pi\beta$ decay
rate constrains CKM unitarity, and, thus, can be used to distinguish among
certain extensions of the minimal Standard Model. Present status of CKM
unitarity, and the PIBETA experiment at PSI are discussed.