title:
Yukawa Corrections to Single Top Quark Production at the Fermilab
  Tevatron in the Two-Higgs-Doublet Models

abstract:
  We calculate Yukawa corrections of order $\alpha_{ew} M_t^2/M_W^2$ to single
top quark production via $q \bar q'\rightarrow t \bar b$ at the Fermilab
Tevatron in the two-Higgs-doublet models. In our calculation we also keep the
terms proportional to $ M_b^2 \tan^2 \beta$ since their effects may become
rather important for large $\tan\beta$. The corrections can amount to more than
a 15\% reduction in the production cross section relative to the tree level
result in the general two-Higgs-doublet model, and a 10\% enhancement in the
minimal supersymmetric model, which might be observable at a high-luminosity
Tevatron.


title:
Experimental constraints on coefficients of $\alpha_S$-expansion of
  Gottfried sum rule

abstract:
  The $x$- and $Q^2$-dependences of the Gottfried sum rule $S_G(x,Q^2)$ based
on the experimental data on proton and deuteron structure functions are
studied. The dependence of $S_G(x,Q^2)$ on $Q^2$ for low $x$ points to flavour
asymmetry of sea quark distributions. For the first time, the coefficients
$c_1, c_2$ of the expansion of $S_G(x,Q^2)$ in $\alpha_S/\pi$ up to second
order are evaluated through the phenomenological analysis of NMC and H1 data.
It is found that $c_1$ is negative while $c_2$ is positive. The obtained result
is in disagreement with QCD predictions for these coefficients. We suggest
measuring the low $x$-dependence of the $F_2^D$ deuteron structure function at
HERA in order to study the $Q^2$-dependence of the Gottfried sum rule.


title: The Lamb Shift of Excited S-Levels in Hydrogen and Deuterium Atoms

abstract:
  A specific combination of $s$-state Lamb shift $\Delta E_L(1s_{1/2}) - n^3
\Delta E_L(ns_{1/2})$ is considered. Its value is calculated both in the
hydrogen and deuterium atoms for $n$ up to 12. The result inludes all
correction which can contribute $1 kHz$ and particulary: one-loop self energy
and vacuum polarization, two-loop contribution. Nuclear finite-size corrections
for the isotopic difference of the combination are also evaluated.


title:
On a Possibility to Determine the Sign of the Polarized Gluon
  Distribution

abstract:
  We investigate the possibility to draw conclusions on the sign of the
spin-dependent gluon distribution, $\Delta G(x, Q^2)$, from existing polarized
DIS data. The spin-dependent parton distributions $\Delta u_v, \Delta d_v,
\Delta {\bar u}, \Delta {\bar d}, \Delta {s}$, and $\Delta G$ are constructed
in the framework of a phenomenological procedure taking into account some
assumptions on signs of valence and sea parton distributions motivated by 't
Hooft's mechanism of quark-quark interaction induced by instantons. The axial
gluon anomaly and data on integral quark contributions to the proton spin,
$\Delta \tilde u, \Delta \tilde d$, and $\Delta \tilde s$, are also taken into
account. Predictions for the $x$- and $Q^2$-dependencies of the polarized
proton and neutron structure functions, $g_1^p$ and $g_1^n$, are compared to
experimental data. It is shown that the neutron structure function, $g_1^n$, is
especially sensitive to the sign of $\Delta G(x, Q^2)$. The results of our
analysis supports the conclusion that this sign should be positive.


title: The Scalar q bar q nonet and Confirmation of the broad sigma meson

abstract:
  The available data on the a0(980), f0(980), f0(1300) and K*0(1430) mesons are
fitted as a distorted 0++ nonet using only 6 parameters and a very general
model. This includes all light two-pseudoscalar thresholds, constraints from
Adler zeroes, flavour symmetric couplings, unitarity and physically acceptable
analyticity. One finds that with the large overall coupling there can appear
two physical resonance poles from only one q bar q state. Thus the f0(980) and
f0(1300) resonance poles are two manifestations of the same s bar s state. On
the other hand, the u bar u state, when unitarized and strongly distorted by
hadronic mass shifts, becomes an extremely broad Breit-Wigner-like background,
with its pole at s =(0.158-i0.235) GeV^2. This is the sigma meson required by
models for spontaneous breaking of chiral symmetry.


title:
Photon splitting above the pair creation threshold in very strong
  magnetic fields

abstract: withdrawn - wrong selection rules used.


title: Lepton Polarization Asymmetry in $B\to K^{(*)} l^+l^-$

abstract:
  We investigate the longitudinal lepton polarization asymmetry in the
exclusive processes $B\to K l^+l^-$ and $B\to K^* l^+l^-$. We include both
short and long-distance contributions to the asymmetry in our discussions. We
find that average values of the polarization asymmetries of the muon and tau
for $B\to K^{(*)}\mu^+\mu^-$ and $B\to K^{(*)}\tau^+\tau^-$ are $-0.8\ (-0.7)$
and $-0.2\ (-0.5)$, respectively.


title: A ${\bf Z}_2$ Classification for 2D Fermion Level Crossing

abstract:
  We demonstrate that the number of fermionic zero modes of the static
$2$-dimensional Dirac operator in the background of $SU(2)$ static gauge-Higgs
field configurations is a topological invariant modulo four. Static
configurations which are everywhere odd under parity with even-parity pure
gauge behaviour at infinity admit $4n$, $n\in {\bf Z},$ zero modes of the
Jackiw-Rebbi (JR) type. Odd-parity configurations with odd-parity pure gauge
behaviour at infinity are topologically disconnected from the vacuum and admit
$4 n + 2$ fermionic zero energy solutions. The classification implies the
collapse of half of the fermion zero modes upon embedding a $2$-dimensional
gauge-Higgs configuration (string) with odd-parity pure gauge behaviour at
infinity into the $3$-dimensional Minkowski space.


title: Drell-Yan asymmetries at HERA-$\vec{\rm N}$

abstract:
  The production of Drell-Yan pairs in the double polarized mode of
HERA-$\vec{{\rm N}}$ is studied at next-to-leading order in QCD. It is found
that a measurement of this observable could yield vital information on the
polarization of the light quark sea in the nucleon.


title: Time-reversal-odd asymmetries at HERA

abstract:
  Longitudinal polarization of the HERA electron beam allows the study of
spatial asymmetries in the final state of single inclusive hadron production in
$\vec{e}p$-collisions. We estimate the size of a particular production
asymmetry which is related to the time reversal properties of the underlying
parton level subprocess.


title:
The Evolution of Unpolarized and Polarized Structure Functions at Small
  $x$

abstract:
  A survey is given of recent developments on the resummed small-$x$ evolution,
in a framework based on the renormalization group equation, of non--singlet and
singlet structure functions in both unpolarized and polarized deep--inelastic
scattering. The available resummed anomalous dimensions are discussed for all
these cases, and the most important analytic and numerical results are
compiled. The quantitative effects of these small-$x$ resummations on the
evolution of the various parton densities and structure functions are
presented, and their present uncertainties are investigated. An application to
QED radiative corrections is given.


title:
The Strong Running Coupling from an Approximate Gluon Dyson-Schwinger
  Equation

abstract:
  Using Mandelstam's approximation to the gluon Dyson-Schwinger equation we
calculate the gluon self-energy in a renormalisation group invariant fashion.
We obtain a non-perturbative $\beta $ function. The scaling behaviour near the
ultraviolet stable fixed point is in good agreement with perturbative QCD. No
further fixed point for positive values of the coupling is found: $\alpha_S$
increases without bound in the infrared.


title: Higher Order Top Squark Decays

abstract:
  Within the Minimal Supersymmetric Standard Model we study the three body
decay of the lighter top squark into a b-quark, a W-boson and the lightest
neutralino and compare this decay with the flavour changing two body decay of
the lighter top squark into a c-quark and the lightest neutralino. We do this
for scenarios where two body decays at tree level are forbidden for the light
top squark. We give the complete analysis for the three body and compare it
with the mentioned two body decay. We discuss our numerical results in view of
the upgraded Tevatron, the LHC and a 500~GeV $e^+ e^-$ Linear Collider.


title: Meson Properties in the Quark Model: A Look at Some Outstanding Problems

abstract:
  This thesis examines three problems of the quark model, split between two
general areas. The general areas are: 1) models of meson decay ($^3P_0$ and
flux-tube breaking), 2) final state interactions (FSI's).
  The three specific problems are: 1) identification of the $f_4(2220)$ state,
2) determination of the mixing angle between the $K_1(1270)$ and $K_1(1400)$
mesons, 3) examination of FSI's in the reaction $\gamma \gamma \rightarrow \pi
\pi$ near threshold.
  A more complete abstract is included in the thesis.


title: Chaos and High-Energy Collisons

abstract:
  The investigations of the gauge boson wave packets collisions in SU(2) Higgs
model are presented. The evolution of the gauge and Higgs fields is studied as
a function of the amplitude and the mass ratio of $M_H/M_W$. We visualize the
restoration of spontaneously broken gauge symmetry during collisions.


title:
Amplitude analysis of reactions pi(-)p->etapi(-)p and pi(-)p->etapi(0)n
  on polarized target and the exotic 1-+ meson

abstract:
  Recently several experimental groups analysed data on $\pi^- p \to \eta \pi^-
p$ and $\pi^- p \to \eta \pi^0 n$ reactions with exotic $1^{-+}$ $P$-wave and
found a conflicting evidence for an exotic meson $I=1 1^{-+} (1405)$. High
statistics data on these reactions are presently analysed by BNL E852
Collaboration. All these analyses are based on the crucial assumption that the
production amplitudes do not depend on nucleon spin. This assumption is in
sharp conflict with the results of measurements of $\pi^- p \to \pi^- \pi^+ n$,
$\pi^+ n \to \pi^+ \pi^- p$ and $K^+ n \to K^+ \pi^- p$ on polarized targets at
CERN which find a strong dependence of production amplitudes on nucleon spin.
To ascertain the existence of exotic meson $1^{-+} (1405)$, it is necessary to
perform a model-independent amplitude analysis of reactions $\pi^- p \to \eta
\pi^- p$ and $\pi^- p \to \eta\pi^0 n$. We demonstrate that measurements of
these reactions on transversely polarized targets enable the required model
independent amplitude analysis without the assumption that production
amplitudes are independent on nucleon spin. We suggest that high statistics
measurements of reactions $\pi^- p \to \eta\pi^- p$ and $\pi^- p \to\eta\pi^0
n$ be made on polarized targets at BNL and at Protvino IHEP, and that
model-independent amplitude analyses of this polarized data be performed to
advance hadron spectroscopy on the level of spin dependent production
amplitudes.


title: Neutrino Flavor Oscillations Using the Dirac Equation

abstract:
  The theory of neutrino flavor rotations is discussed in terms of wave
function solutions to the Dirac equation with a neutrino mass matrix. We give a
critical review of the nature of neutrino oscillations.


title: A New Approach to the Yukawa Puzzle

abstract:
  We do a systematic analysis of the question of calculability of CKM matrix
elements in terms of quark mass ratios, within the framework of the hypothesis
of universality of strength for Yukawa couplings (USY), where all Yukawa
couplings have equal moduli, and the flavor dependence is only in their phases.
We use the fact that the limit $m_u=m_d=0$ is specially simple in USY, to
construct the various ans\"atze. It is shown that the experimentally observed
CKM matrix can be obtained within USY ans\"atze corresponding to simple
relations among phases of Yukawa couplings. Within USY, one finds a natural
explanation why Cabibbo mixing is significantly larger than the other CKM
mixings. In the most successful of the USY ans\"atze, one obtains in leading
order: $|V_{us}|=\sqrt{m_d/{m_s}}$ ; $ |V_{cb}|=\sqrt{2}(m_s/m_b)$ $ |V_{ub}|=
(1/\sqrt{2})\sqrt{m_dm_s/m_b^2}$ ; $|V_{td}|= 3|V_{ub}|$. We study the behavior
of this USY ansatz under the renormalization group.


title:
Problem of the Complete Measurement for CP-violating Parameters in
  Neutral B-meson Decays

abstract:
  Phenomenological CP-violating parameters in decays of neutral B-mesons are
discussed. Special attention is given to the degree of their measurability. We
emphasize important role of the sign of $\Delta m_B$ and suggest how it could
be determined experimentally.


title: Testing QCD Predictions for Multiplicity Distributions at HERA

abstract:
  On the basis of a recently introduced generalization of the negative binomial
distribution the influence of higher-order perturbative QCD effects on
multiplicity fluctuations are studied for deep inelastic e^+p scattering at
HERA energies. It is found that the multiplicity distributions measured by the
H1 Collaboration indicate violation of infinite divisibility in agreement with
pQCD calculations. Attention is called to future experimental analysis of
combinants whose nontrivial sign-changing oscillations are predicted using the
generalized negative binomial law.


title:
Corrections of order $\alpha_s^3$ to $R_{had}$ in pQCD with light
  gluinos

abstract:
  By a completely independent analytic calculation made in general covariant
gauge we confirm the known result for the massless $\alpha_s^3$ correction to
$R_{had}$ and check explicitly its gauge independence. We extend the
calculations to include contributions due to a hypothetical existence of a
colour octet of (light) neutral fermions known also under the name of gluinos.


title:
Matching Experimental and Theoretical Jet Definitions for
  Photoproduction at HERA

abstract:
  Predictions from a new next-to-leading order (NLO) calculation for direct and
resolved photoproduction of one and two jets are compared to simulated HERA
data. We propose a method to match experimental and theoretical jet definitions
and observe a reduced dependence on jet definitions and hadronization
corrections at larger transverse energies. From the irreducible uncertainty, we
estimate the maximum benefit that can be obtained from increased luminosity to
constrain the structure of the photon and the proton.


title:
The Temperature Dependence of the SU(N) Gluon Condensate from Lattice
  Gauge Theory

abstract:
  An analysis of the temperature dependence of the leading contributions to the
gluon condensate for SU(N) lattice gauge theory is presented using the data
from recent Monte Carlo simulations. The gluon condensate is calculated
directly from the new lattice calculations of the interaction measure. It is
shown how these computations provide a simple picture for the melting of the
condensate around the deconfinement temperature, and the fact that it is
negative, and increases in magnitude, above Tc. We close with a discussion of
the implications for full QCD of recent results from simulations including
fermions.


title: Leptoquark Pair Production at HERA

abstract:
  The scalar and vector leptoquark pair production cross sections for deep
inelastic $ep$ scattering are calculated. Estimates are presented for the
search potential at HERA.


title:
Nuclear Structure-Dependent Radiative Corrections to the Hydrogen
  Hyperfine Splitting

abstract:
  Radiative corrections to the Zemach contribution of the hydrogen hyperfine
splitting are calculated. Their contributions amount to $-0.63(3)$ ppm to the
HFS. The radiative recoil corrections are estimated to be $0.09(3)$ ppm and
heavy particle vacuum polarization shifts the HFS by $0.10(2)$ ppm. The status
of the nuclear-dependent contributions are considered. From the comparison of
theory and experiment the proton polarizability contribution of $3.5(9)$ ppm is
found. The nuclear structure-dependent corrections to the difference
$\nu_{hfs}(1s) -n^3\nu_{hfs}(ns)$ are also obtained.


title: Proposed Tests of CPT Symmetry Using D Mesons

abstract:
  Parameters describing CPT violation are extracted from a variety of rate
asymmetries in the neutral-$D$ system. The precision to which these parameters
could be measured in present and planned machines is examined.


title:
Hadronic Antenna Patterns to Distinguish Production Mechanisms for
  Large-E_T Jets

abstract:
  Hadronic antenna patterns provide a tool able to diagnose different patterns
of colour flow in large-E_T jet events. They reflect the underlying
short-distance dynamics, and are sensitive to colour coherence and interference
between the initial- and final-state partons. We discuss how hadronic antenna
patterns may be used on large-E_T events from the Fermilab Tevatron or the CERN
LHC to distinguish between conventional QCD and new physics production
mechanisms such as a possible Z' boson or compositeness.


title: Symmetrization Selection Rules

abstract:
  We introduce strong and electromagnetic interaction selection rules for the
two-body decay and production of exotic J^{PC} = 0^{+-}, 1^{-+}, 2^{+-}, 3^{-+}
hybrid mesons, four-quark states and glueballs. The rules arise from
symmetrization in states. Examples include various decays to eta' eta, eta pi,
eta' pi and pi^{\pm} pi^0. The symmetrization rules can discriminate between
hybrid and four-quark interpretations of a 1^{-+} signal.


title:
LanHEP - a package for automatic generation of Feynman rules in gauge
  models

abstract:
  We consider the general problem of derivation of the Feynman rules for the
matrix elements in momentum representation from the given Lagrangian in
coordinate space invariant under the transformation of some gauge group. LanHEP
package presented in this paper allows to define in a convenient way the gauge
model Lagrangian in canonical form and then to generate automatically the
Feynman rules that can be used in the following calculation of the physical
processes by means of CompHEP package. The detailed description of LanHEP
commands is given and several examples of LanHEP applications (QED, QCD,
Standard Model in the t'Hooft-Feynman gauge) are presented.


title: Theoretical Summary

abstract:
  After a quick tour through the present status of the Standard Model, an
attempt is made to set up a framework to discuss some presently available
exotica, including $R_b$ and the CDF $ee\gamma\gamma+E_T\hskip-13pt/\ $
``event." Supersymmetry seems to be a key player in establishing a paradigm
shift beyond the Standard Model. (XI Topical Workshop on Proton-antiproton
Collider Physics, Abano Terme (Padua), Italy, 26 May-1 June, 1996.)


title: QCD at Large $\theta$ Angle and Axion Cosmology

abstract:
  We use the chiral Lagrangian to investigate the global properties of the
$N$-flavor QCD vacuum as a function of the $\theta$ parameter. In the case of
exact quark degeneracy we find evidence for first order phase transitions at
$\theta = \pi \cdot ({\rm odd~ integer})$. The first order transitions are
smoothed by quark mass splittings, although interesting effects remain at
realistic quark masses. We emphasize the role of the $\eta'$ condensate in our
analysis. Finally, we discuss the implications of our results on the internal
hadronic structure of axion domain walls and axion cosmology.


title:
Effective field theories for QED bound states: extending Nonrelativistic
  QED to study retardation effects

abstract:
  Nonrelativistic QED bound states are difficult to study because of the
presence of at least three widely different scales: the masses, three-momenta
($p_i$) and kinetic energies ($K_i$) of the constituents. Nonrelativistic QED
(NRQED), an effective field theory developed by Caswell and Lepage, simplifies
greatly bound state calculations by eliminating the masses as dynamical scales.
As we demonstrate, NRQED diagrams involving only photons of energy $E_\gamma
\simeq p_i$ contribute, in any calculation, to a unique order in $\alpha$. This
is not the case, however, for diagrams involving photons with energies
$E_\gamma \simeq K_i$ (``retardation effects"), for which no simple counting
counting rules can be given. We present a new effective field theory in which
the contribution of those ultra-soft photons can be isolated order by order in
$\alpha$. This is effectively accomplished by performing a multipole expansion
of the NRQED vertices.


title:
Color Transparency and Color Opacity in Coherent Production of Vector
  Mesons off Light Nuclei at small x

abstract:
  Coherent electroproduction of vector mesons off $^2$H and $^4$He is
considered in the kinematics of deep inelastic scattering. Special emphasis is
given to the $-t\sim 0.8-1$ GeV$^2$ region where the cross section is dominated
by the interaction of the $q\bar q$ configuration in the $\gamma^*$ with two
nucleons. These kinematics provide the unique possibilities to study
quantitatively in vector meson production the onset of Color Transparency with
increasing $Q^2$ as well as its gradual disappearance at very small $x$, i.e.,
perturbative Color Opacity.


title: Nonperturbative Renormalization of QED in Light-Cone Quantization

abstract:
  As a precursor to work on QCD, we study the dressed electron in QED
nonperturbatively. The calculational scheme uses an invariant mass cutoff,
discretized light-cone quantization, a Tamm--Dancoff truncation of the Fock
space, and a small photon mass. Nonperturbative renormalization of the coupling
and electron mass is developed.


title:
Laboratory Constraints on a 33.9 MeV/c^2 Isosinglet Neutrino: Status and
  Perspectives

abstract:
  An anomaly in the time behaviour of the signals observed by the KARMEN
Collaboration may be interpreted as the possible decay signature of a 33.9
MeV/c$^2$ mainly sterile neutrino. This note discusses the parameter space
still open for the mixing of this hypothetical particle with the neutrinos of
known leptonic flavour, considering the experimental results which became
available recently, as well as those to be expected from forthcoming
measurements. It is concluded that if no positive signature is observed, the
envisaged laboratory experiments are not expected to close enterily the
parameter space of mixing amplitudes. However, a proper reassessment of the
ALEPH upper bound on the $\nu_\tau$ neutrino mass including the possibility of
$\tau$ flavour mixing, would certainly help in reducing the parameter space
left open.


title:
Quadratic Mass Corrections of Order $\alpha_s^3 m_q^2/s$ to the Decay
  Rate of Z- and W- Bosons

abstract:
  We analytically compute quadratic mass corrections of order $\alpha_s^3
m_q^2/s$ to the absorptive part of the (non-diagonal) correlator of two axial
vector currents. This allows us to find the correction of order $\alpha_s^3
m_q^2/M^2_W$ to the $\Gamma(W -->hadrons)$ as well as similar corrections to
$\Gamma(Z -->hadrons)$.


title: An Observation on F_2 at Low x

abstract:
  A simple parametrisation of H1 and ZEUS data at HERA is given for the ranges
in x and Q^2 of 10^{-4} - 5.10^{-2} and 5 - 250 GeV^2, respectively. This
empirical expression is based on a strikingly similar dependence of the average
charged particle multiplicity <n> on the centre of mass system energy sqrt{s}
in e+e- collisions on the one hand, and the x dependence of the proton
structure function F_2 as measured at small x on the other hand. To the best of
our knowledge, this similarity has not been noted before.


title: Implications of the Quark Mass Hierarchy on Flavor Mixings

abstract:
  We stress that the observed pattern of flavor mixings can be partly
interpreted by the quark mass hierarchy without the assumption of specific
quark mass matrices. The quantitatively proper relations between the
Kobayashi-Maskawa matrix elements and quark mass ratios, such as $$|V_{cb}|
\approx |V_{ts}| \approx \sqrt{2} (\frac{m_s}{m_b} -\frac{m_c}{m_t}) [1 + 3
(\frac{m_s}{m_b} + \frac{m_c}{m_t} ) ],$$ are obtainable from a simple {\it
Ansatz} of flavor permutation symmetry breaking at the weak scale. We prescribe
the same {\it Ansatz} at the supersymmetric grand unified theory scale, and
find that its all low-energy consequences on flavor mixings and $CP$ violation
are in good agreement with current experimental data.


title: Back-reaction in the presence of thermalizing collisions

abstract:
  Preequilibrium parton production following an ultrarelativistic
nucleus--nucleus collision is studied in terms of the decay of a strong
chromoelectric field which generates pairs through the Schwinger mechanism.
Back-reaction of the partons with the field is included and a model transport
equation containing a collision term is solved for the central rapidity region
based on an approximation in which the partons relax to a thermal distribution.


title: Heavy flavour tagging and QCD tests in four-jet events at LEP1

abstract:
  We present a theoretical review of the possibilities offered by heavy flavour
tagging in testing QCD features in 4-jet events at LEP1. Attention is focused
mainly on the properties of the angular variables which are used in the
experimental analyses to measure the colour factors of the strong interactions.
We also comment on a possible settlement of the ongoing controversy about the
existence in LEP1 data of SUSY events involving light gluinos. Integrated and
differential rates of interest to phenomenological analyses are given and
various tagging procedures are discussed.


title: $Q^2$ evolution of chiral-odd twist-3 distribution $e(x,Q^2)$

abstract:
  We study the $Q^2$ dependence of the chiral-odd twist-3 distribution
$e(x,Q^2)$.The anomalous dimension matrix for the corresponding twist-3
operators is calculated in the one-loop level. This study completes the
calculation of the anomalous dimension matrices for all the twist-3
distributions together with the known results for the other twist-3
distributions $g_2(x,Q^2)$ and $h_L(x,Q^2)$. We also have confirmed that in the
large $N_c$ limit the $Q^2$-evolution of $e(x,Q^2)$ is wholely governed by the
lowest eigenvalue of the anomalous dimension matrix which takes a very simple
analytic form as in the case of $g_2$ and $h_L$.


title: New Predictions for Charmed and Bottom Baryons

abstract:
  I review the recent proposal that there are new isotriplet heavy baryons with
masses approximately 2380 MeV and 5760 MeV. This prediction follows from the
application of heavy spin-flavor and light $SU(3)$ symmetries to the observed
charmed and bottom baryon states. It also entails assumptions about the spin
and parity quantum numbers of the observed states which are different than is
commonly supposed. The discovery of such states would imply that the
nonrelativistic constituent quark model is a poor predictor of heavy baryon
spectroscopy. I update the analysis in light of new data which have become
available.


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

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


title: Searching for a Light Stop at the Tevatron

abstract:
  We describe a method to help the search for a light stop squark [M(stop) +
M(LSP) < M(top)] at the Fermilab Tevatron. Traditional search methods rely upon
a series of stringent background-reducing cuts which, unfortunately, leave very
few signal events given the present data set. To avoid this difficulty, we
instead suggest using a milder set of cuts, combined with a "superweight,"
whose purpose is to discriminate between signal and background events. The
superweight consists of a sum of terms, each of which are either zero or one.
The terms are assigned event-by-event depending upon the values of various
observables. We suggest a method for choosing the observables as well as the
criteria used to assign the values such that the superweight is "large" for the
supersymmetric signal and "small" for the standard model background. For
illustration, we mainly consider the detection of stops coming from top decay,
making our analysis especially relevant to the W+2 jets top sample.


title: Baryon-Number Nonconservation and the Stability of Strange Matter

abstract:
  If baryon-number nonconservation exists in the form of an effective six-quark
operator which also changes strangeness by four units, it could have a
tremendous impact on the absolute stability of strange quark matter. We show
that such an operator is negligible in the supersymmetric standard model with
$\lambda_{ijk} u_i^c d_j^c d_k^c$ terms in the superpotential, but may be of
importance in models with exotic particle content. From the experimental lower
limit of $10^{25}$ years on the stability of nuclei, we find a
model-independent lower limit of the order $10^5$ years on the stability of
strange matter against such decays.


title: Supersymmetric Scenarios with Dominant Radiative Neutralino Decay

abstract:
  The radiative decay of the next-to-lightest neutralino into a lightest
neutralino and a photon is analyzed in the MSSM. We find that significant
regions of the supersymmetric parameter space with large radiative BR's (up to
about 100%) do exist. The radiative channel turns out to be enhanced when the
neutralino tree-level decays are suppressed either "kinematically" or
"dynamically". In general, in the regions allowed by LEP data and not
characterized by asymptotic values of the SuSy parameters, the radiative
enhancement requires tan beta ~= 1 and/or M_1 ~= M_2, and negative values of
\mu. We present typical specific scenarios where these "necessary" conditions
are fulfilled, relaxing the usual relation M_1=(5/3)*tan^2(th_W)*M_2. The
influence of varying the stop masses and mixing angle when the radiative decay
is enhanced is also considered. Some phenomenological consequences of the above
picture are discussed.


title: Quark mass effects in QCD jets

abstract:
  We present the calculation of the decay width of the Z-boson into three jets
including complete quark mass effects to second order in the strong coupling
constant. The study is done for different jet clustering algorithms such as EM,
JADE, E and DURHAM. Because three-jet observables are very sensitive to the
quark mass we consider the possibility of extracting the bottom quark mass from
LEP data.


title: Lifetime Difference of Neutral $B_s$ Mesons and its Implications

abstract:
  We discuss the calculation of the width difference $\Delta\Gamma_{B_s}$
between the $B_s$ mass eigenstates to next-to-leading order in the heavy quark
expansion. $1/m_b$-corrections are estimated to reduce the leading order result
by typically $30\%$. The error of the present estimate
$(\Delta\Gamma/\Gamma)_{B_s} = 0.16^{+0.11}_{-0.09}$ could be substantially
improved by pinning down the value of $\langle \bar{B}_s |(\bar
b_is_i)_{S-P}(\bar b_js_j)_{S-P}| B_s\rangle$ and an accuracy of $10\%$ in
$(\Delta\Gamma/\Gamma)_{B_s}$ should eventually be reached. We briefly mention
strategies to measure $(\Delta\Gamma/\Gamma)_{B_s}$, and its implications for
constraints on $\Delta M_{B_s}$, CKM parameters and the observation of CP
violation in untagged $B_s$ samples.


title: Power Corrections, Renormalons and Resummation

abstract:
  I briefly review three topics of recent interest concerning power
corrections, renormalons and Sudakov resummation: (a) $1/Q$ corrections to
event shape observables in $e^+ e^-$ annihilation, (b) power corrections in
Drell-Yan production and (c) factorial divergences that arise in resummation of
large infrared (Sudakov) logarithms in moment or `real' space.


title: Rho primes in analyzing e+e- annihilation, MARK III, LASS and ARGUS data

abstract:
  The results of an analysis are presented of some recent data on the reactions
$e^+e^-\to\pi^+\pi^-\pi^+\pi^-$, $e^+e^-\to\pi^+\pi^-\pi^0\pi^0$ with the
subtracted $\omega\pi^0$ events, $e^+e^-\to\omega\pi^0$, $e^+e^-\to\eta
\pi^+\pi^-$, $e^+e^-\to\pi^+\pi^-$, $K^-p\to\pi^+\pi^-\Lambda$, the decays
$J/\psi\to\pi^+\pi^-\pi^0$, $tau^-\to\nu_tau\pi^+\pi^-\pi^-\pi^0$
$tau^-\to\nu_\tau\omega\pi^-$, upon taking into account both the strong energy
dependence of the partial widths on energy and the previously neglected mixing
of the $\rho$ type resonances. The above effects are shown to exert an
essential influence on the specific values of masses and coupling constants of
heavy resonances and hence are necessary to be accounted for in establishing
their true nature.


title:
Theoretical Uncertainties in the QCD Evolution of Structure Functions
  and their Impact on $\alpha_s(M_Z^2)$

abstract:
  The differences are discussed between various next-to-leading order
prescriptions for the QCD evolution of parton densities and structure
functions. Their quantitative impact is understood to an accuracy of 0.02\%.
The uncertainties due to the freedom to choose the renormalization and
factorization scales are studied. The quantitative consequences of the
different uncertainties on the extraction of the strong coupling constant
$\alpha_s$ from scaling violations in deep--inelastic scattering are estimated
for the kinematic regime accessible at HERA.


title: Perturbative Unification of Soft Supersymmetry--Breaking Terms

abstract:
  Perturbative unification of soft supersymmetry--breaking (SSB) parameters is
proposed in Gauge-Yukawa unified models. The method, which can be applied in
any finite order in perturbation theory, consists in searching for
renormalization group invariant relations among the SSB parameters, which are
consistent with perturbative renormalizability. For the minimal Gauge-Yukawa
unified model based on $SU(5)$ we find that the low energy SSB sector contains
a single arbitrary parameter, the unified gaugino mass. Within a certain
approximation we find that the model predicts a superpartner spectrum which is
consistent with the experimental data.


title: Domain Walls are Diamagnetic

abstract:
  It is shown that contrary to a recent claim in the literature, the domain
walls made of scalar field are diamagnetic due to presence of massless
fermionic modes on the wall. The diamagnetism vanishes at high temperature.
Thus the domain walls could produce no effect on a primordial magnetic field in
the early universe.


title: Search For Non-Standard Model CP/T violation At Tau-Charm Factory

abstract:
  We systematically investigate the possibility of finding CP/T violation in
the $\tau$ sector at Tau-Charm Factory. CP/T violation may occur at $\tau$ pair
production process, expressed as electric dipole moment, and at $tau$ decay
processes. By assuming that electric dipole moment as large as $10^{-19}$e-cm
and CP/T violation effect orignating from $\tau$ decay as large as $10^{-3}$
are observable at Tau-Charm Factory, we studied all the possible extensions of
the SM which are relevent for generating CP/T violation in $\tau$ sector. And
we pointed there are a few kind of models, which are hopeful for generating
such CP/T violation. For these models we consider all the theoretical and
current experimental constraints and find that there exists some parameter
space which will result in a measurable CP/T violation. Therefore we conclude
that Tau-Charm Factory is a hopeful place to discover CP/T violation in $\tau$
sector.


title: The strong CP problem versus Planck scale physics

abstract:
  We discuss conditions that should be satisfied by axion models for solving
the strong CP problem. It has been observed that Planck scale effects may
render the axion models ineffective if there are gauge invariant operators of
dimension less than 10 which break explicitly the Peccei-Quinn (PQ) symmetry.
We argue that only those operators formed of fields which have vacuum
expectation values are dangerous. Supersymmetric axion models fail to prevent
even this restricted class of operators. Furthermore, the models that relate
the PQ scale and the supersymmetry breaking scale are particularly sensitive to
gauge invariant PQ-breaking operators. By contrast, in non-supersymmetric
composite axion models the PQ scale arises naturally, and the dangerous
operators can be avoided. However, the composite axion models contain heavy
stable particles which are cosmologically ruled out. Another problem is a
Landau pole for the QCD coupling constant. Both these problems may be solved if
the unification of color with the gauge interactions which bind the axion could
be achieved.


title: Weak electricity of the Nucleon in the Chiral Quark-Soliton Model

abstract:
  The induced pseudotensor constant (weak electricity) of the nucleon is
calculated in the framework of the chiral quark soliton model. This quantity
originates from the G-parity violation and hence is proportional to $m_u-m_d$.
We obtain for $m_u-m_d=-5 MeV$ a value of $g_T/g_A =-0.0038$.


title: High Temperature QCD

abstract:
  I discuss finite-temperature gauge theories as a framework to describe the
quark-gluon plasma in the regime of high temperature where the gauge coupling
is small, $g << 1$. I review recent progress in the understanding of the
long-range physics, with emphasis on the collective phenomena and their
consequences for the screening of the gauge interactions. I consider some of
the infrared divergences of the perturbation theory, and discuss the physical
mechanisms which remove these divergences.


title: Lifetime of quasiparticles in hot gauge theories

abstract:
  The perturbative calculation of the lifetime of charged excitations in
ultrarelativistic plasmas is plagued with infrared divergences which are not
eliminated by the screening corrections. The physical processes responsible for
these divergences are the collisions involving the exchange of longwavelength,
quasistatic, magnetic gluons (or photons), which are not screened by plasma
effects. In QED, the leading divergences can be resummed in a non-perturbative
treatement based on a generalization of the Bloch-Nordsieck model at finite
temperature. The resulting expression of the fermion propagator is free of
infrared problems, and exhibits a ``non-exponential'' damping at large times:
$S_R(t)\sim exp {-\alpha T t ln\omega_pt}$, where $\omega_p=eT/3$ is the plasma
frequency and $\alpha=e^2/4\pi$.


title: The quasiparticle structure of hot gauge theories

abstract:
  The study of the ultrarelativistic plasmas in perturbation theory is plagued
with infrared divergences which are not eliminated by the screening
corrections. They affect, in particular, the computation of the lifetime of the
elementary excitations, thus casting doubt on the validity of the quasiparticle
picture. We show that, for Abelian plasmas at least, the infrared problem of
the damping rate can be solved by a non-perturbative treatment based on the
Bloch-Nordsieck approximation. The resulting expression of the fermion
propagator is free of divergences, and exhibits a {\it non-exponential} damping
at large times: $S_R(t)\sim \exp\{-\alpha T t \ln\omega_pt\}$, where
$\omega_p=gT/3$ is the plasma frequency and $\alpha=g^2/4\pi$.


title: Polarized Nucleon Structure Functions within a Chiral Soliton Model

abstract:
  We study polarized-spin structure functions of the nucleon within the
bosonized Nambu-Jona-Lasinio model where the nucleon emerges as a chiral
soliton. We present the electromagnetic polarized structure functions,
$g_{1}(x)$ and $g_{2}(x)$ for $ep$ scattering and discuss various sum rules in
the valence quark approximation. This approximation is justified because in
this model axial properties of the nucleon are dominated by their valence quark
contributions. We find that these structure functions are well localized in the
interval $0\le x \le1$. We compare the model predictions on the polarized
structure functions with data from the E143 experiment by evolving them from
the scale characteristic of the NJL-model to the scale of the data.
Additionally a comparison is made with parameterized data at a momentum scale
commensurate with the model calculation.


title: Rapidity Gaps Between Jets

abstract:
  An excess of events with a rapidity gap between jets, over what would be
expected from non-diffractive processes, has been observed at HERA. A process
based on a perturbative QCD calculation of colour singlet exchange has been
added to HERWIG. With this addition, HERWIG is able to describe the number of
events with a gap between jets over the number without a gap. This gap fraction
is predicted to rise at large rapidity intervals between jets which would only
be visible if the detector coverage were increased.


title: Centauro as Probe of Deeply Penetrating Component in Cosmic Rays

abstract:
  The requirements for observing Centauro-like phenomena and their role as
possible probes of deeply penetrating component in Cosmic Rays are discussed.


title: Meson Masses in Nuclear Matter

abstract:
  Mass shifts $\Delta m$ of particles in nuclear matter relative to their
vacuum values are considered. A general formula relating $\Delta m(E)$ ($E$ is
the particle energy) to the real part of the forward particle-nucleon
scattering amplitude ${\rm Re} f(E)$ is presented and its applicability domain
is formulated. The $\rho$-meson mass shift in nuclear matter is calculated at
$2\la E_{\rho}\la 7$ GeV for transversally and longitudinally polarized
$\rho$-mesons with the results: $\Delta m_{\rho}^T \sim 50$ MeV and $\Delta
m_{\rho}^L \sim 10$ MeV at normal nuclear density.


title: Early History of Gauge Theories and Weak Interactions

abstract:
  Invited talk at the PSI Summer School on Physics with Neutrinos, Zuoz,
Switzerland, August 4-10, 1996.


title:
Forward Jet Production at HERA in the Low $x$ Regime in Next-to-Leading
  Order

abstract:
  The production of forward jets of transverse momentum $p_T(j)\approx Q$ and
large momentum fraction $x_{jet}\gg x$ probes the onset of BFKL dynamics at
HERA. A full ${\cal O}(\alpha_s^2)$ calculation of the inclusive forward jet
cross section is presented and compared to the expected BFKL cross section. The
kinematical region populated by these events and the scale dependence of the
fixed order perturbative QCD cross sections are discussed.


title: Could Spontaneous Transitions be Spontaneous?

abstract:
  It is considered to re-formulate quantum theory as it appears: A theory of
continuous and causal time evolution, interrupted by discontinuous and
stochastic jumps. To develop the (missing) theory of jumps a
heuristic-phenomenological approach is suggested. Relying on a global reduction
process, a hypothesis is introduced postulating spontaneous collapse of
superpositions of states which describe spontaneous absorption or emission. The
collapse probability determines a mean collapse time $\tau^c = b \hbar /
\triangle E$, where $b$ is a dimensionless constant and $\triangle E$ is the
difference in energy distribution between alternative branches. Ramsey atomic
beam spectroscopy yields a lower bound on $b$ and avalanche photodiodes give an
upper bound, such that $1.35\cdot 10^{11} < b < 3.8\cdot 10^{21}$. Ample
opportunities for experimental improvements exist.


title:
Nonperturbative evaluation of a field correlator appearing in the heavy
  quarkonium system

abstract:
  Recently an electric and magnetic field correlator appearing in the
description of the heavy quarkonium system was evaluated on the lattice. Here,
we give a nonperturbative analytical evaluation of this field correlator using
a dual description of long distance Yang--Mills theory and using the stochastic
vacuum model. The two predictions are both compatible with lattice data but
show a different dependence on the quark separation. We discuss the analytic
results in relation to the lattice data.


title: Unitarity Effects at Low x

abstract:
  We discuss effects of unitarity on the low-x behaviour of the structure
functions of deeply inelastic scattering. Particular attention is paid to the
distinction between Regge and Renormalization Group $J$-plane singularities and
their relative weight in defining the low-x asymptotics.


title:
Light, long-lived and secluded: can gluinos be driven out from LEP1 data
  ?

abstract:
  We briefly report about a possible settlement of the still ongoing dispute
concerning the existence of SUSY signals in 4jet events at LEP1. We base our
arguments on a simple selection strategy exploiting secondary vertex tagging
and kinematical constraints, which could allow one to access or exclude gluino
events for a broad range of masses and lifetimes.


title: Onium Production

abstract:
  The present status of our understanding of onium production is reviewed.
Different models are described and comparisons of theoretical predictions with
experimental data are given.


title:
QCD jet calculations in DIS based on the subtraction method and dipole
  formalism

abstract:
  We briefly describe a new general algorithm for carrying out QCD calculations
to next-to-leading order in perturbation theory. The algorithm can be used for
computing arbitrary jet cross sections in arbitrary processes and can be
straightforwardly implemented in general purpose Monte Carlo programs. We show
numerical results for the specific case of jet cross sections in deep inelastic
scattering.


title: Simple Amplitudes for \Phi^3 Feynman Ladder Graphs

abstract:
  Recently, we proposed a new approach for calculating Feynman graphs amplitude
using the Gaussian representation for propagators which was proven to be exact
in the limit of graphs having an infinite number of loops. Regge behavior was
also found in a completely new way and the leading Regge trajectory calculated.
Here we present symmetry arguments justifying the simple form used for the
polynomials in the Feynman parameters $\bar \alpha _{\ell}$, where $\bar \alpha
_{\ell}$ is the mean-value for these parameters, appearing in the amplitude for
the ladder graphs. (Taking mean-values is equivalent to the Gaussian
representation for propagators).


title: Quark-Antiquark Jets in DIS Diffractive Dissociation

abstract:
  We report on investigations concerning the production of large transverse
momentum jets in DIS diffractive dissociation. These processes constitute a new
class of events that allow for a clean test of perturbative QCD and of the hard
(perturbative) pomeron picture. The measurement of the corresponding cross
sections might possibly serve to determine the gluon density of the proton.


title: Electroweak Phase Transition in Two Higgs Doublet Models

abstract:
  We reexamine the strength of the first order phase transition in the
electroweak theory supplemented by an extra Higgs doublet. The
finite-temperature effective potential, $V_{eff}$, is computed to one-loop
order, including the summation of ring diagrams, to study the ratio
$\phi_c/T_c$ of the Higgs field VEV to the critical temperature. We make a
number of improvements over previous treatments, including a consistent
treatment of Goldstone bosons in $V_{eff}$, an accurate analytic approximation
to $V_{eff}$ valid for any mass-to-temperature ratios, and use of the
experimentally measured top quark mass. For two-Higgs doublet models, we
identify a significant region of parameter space where $\phi_c/T_c$ is large
enough for electroweak baryogenesis, and we argue that this identification
should persist even at higher orders in perturbation theory. In the case of the
minimal supersymmetric standard model, our results indicate that the extra
Higgs bosons have little effect on the strength of the phase transition.


title:
Effects of Neutrino Oscillation on the Supernova Relic Neutrino
  Background

abstract:
  We investigate to what extent the oscillation or conversion of neutrinos
enhances the expected event rate of the supernova relic neutrino background
(SRN) at the Super-Kamiokande detector (SK). The SRN \bar\nu_e's can be almost
completely exchanged with \nu_\mu-like neutrinos by the MSW oscillation under
the inverse mass hierarchy with \Delta m^2 ~ 10^{-8}--10^5 [eV^2], or by the
magnetic moment of Majorana neutrinos with \mu_\nu >~ 10^{-12} \mu_B and \Delta
m^2 ~ 10^{-4}--10^0 [eV^2]. In the standard calculation of the SRN flux, the
event rate of the SRN \bar\nu_e's at the SK in the observable energy range of
15--40 MeV can be enhanced from 1.2 yr^{-1} to 2.4 yr^{-1} if all \bar\nu_e's
are exchanged with \nu_\mu-like neutrinos. The enhancement is prominent
especially in the high energy range (\gtilde 25 MeV). In the astrophysically
optimistic calculation, the event rate becomes as high as 9.4 yr^{-1}. Because
the theoretical upper bound of the SRN events without oscillation is about 5
yr^{-1} taking account of the various astrophysical uncertainties, we might
have to resort to the neutrino oscillation if more than 5 events in a year, as
well as a significantly harder spectrum, were observed in the SK.


title: Strangeness Enhancement in Sulphur-Nucleus Collisions at 200 GeV/N

abstract:
  The NA35 experiment used several independent methods to determine the strange
particle production in p+S and S+A collisions. The different techniques show
consistent results. Strangeness conservation in full phase space is used as an
additional check of the consistency of the data.
  On the base of the analysis in full phase space it could be shown that
strangeness conservation is fullfilled. The NA35 K$^0_S$ in S+S and S+Ag are
consistent with the NA44 results for K$^+$ and K$^-$. The results of the NA36
collaboration for S+Pb collisions were extrapolated to full phase space. The
comparison with the NA35 results shows more than two times lower yields. The
ratio of $\Lambda$ to $\overline{\Lambda}$ at midrapidity of NA36 is
inconsistent with the high baryon density determind by NA35. The strange
particle production is compared to the abundance of non strange particles,
especially negatively charged pions which are measured in full phase space in
the same experiment. A clear enhanced strange hadron production relative to
$\pi^-$ is observed in S+Ag collisions compared to p+S reactions at the same
energy. The K$^0_S$ multiplicity in full phase space per negative hadron
(h$^-$) in S+S, S+Ag and Pb+Pb is enhanced by about a factor 1.6 compared to
N+N and p+S collisions. The NA36 result for the K$^0_S$ multiplicity per h$^-$
in S+Pb is below the N+N value.


title: Review of higher order QCD corrections to structure functions

abstract:
  A review is presented on all higher order QCD corrections to deep inelastic
structure functions. The implications of these corrections for polarized and
unpolarized deep inelastic lepton-hadron scattering will be discussed.


title:
Discrepancy-based error estimates for Quasi-Monte Carlo. III: Error
  distributions and central limits

abstract:
  In Quasi-Monte Carlo integration, the integration error is believed to be
generally smaller than in classical Monte Carlo with the same number of
integration points. Using an appropriate definition of an ensemble of
quasi-randompoint sets, we derive various results on the probability
distribution of the integration error, which can be compared to the standard
Central Limit theorem for normal stochastic sampling. In many cases, a Gaussian
error distribution is obtained.


title: Hard diffractive scattering: partons and QCD

abstract:
  The HERA diffractive structure function data are interpreted in terms of
`diffractive parton distributions' which satisfy DGLAP evolution. These
distributions are modeled assuming that the scattering takes place off a colour
singlet `pomeron' target. A quantitative test of the universality of
diffractive parton distributions is proposed.


title: Gluon Radiation in $t\bar t$ Production and Decay at the LHC

abstract:
  Understanding the pattern of gluon radiation in $t \bar t$ production and
decay processes is important for making an accurate determination of the top
mass from the momenta of its decay products. The larger energy of the LHC $pp$
collider boosts the top cross section by a factor of 100 compared to that at
the Tevatron, but it also increases the amount of additional gluon radiation.
We calculate the cross section for gluon radiation in top production and decay
at the LHC. The distributions of this radiation are presented and the exact
matrix-element results are compared with results from the HERWIG parton-shower
Monte Carlo.


title: Chiral Symmetry Breaking in QCD: A Variational Approach

abstract:
  We develop a "variational mass" expansion approach, recently introduced in
the Gross--Neveu model, to evaluate some of the order parameters of chiral
symmetry breakdown in QCD. The method relies on a reorganization of the usual
perturbation theory with the addition of an "arbitrary quark mass $m$, whose
non-perturbative behaviour is inferred partly from renormalization group
properties, and from analytic continuation in $m$ properties. The resulting
ansatz can be optimized, and in the chiral limit $m \to 0$ we estimate the
dynamical contribution to the "constituent" masses of the light quarks
$M_{u,d,s}$; the pion decay constant $F_\pi$ and the quark condensate $< \bar q
q >$.


title: Searches for New Gauge Bosons at Future Colliders

abstract:
  The search reaches for new gauge bosons at future hadron and lepton colliders
are summarized for a variety of extended gauge models. Experiments at these
energies will vastly improve over present limits and will easily discover a
$Z'$ and/or $W'$ in the multi-TeV range. [To appear in the Proceedings of the
1996 DPF/DPB Summer Study on New Directions for High Energy Physics-Snowmass96,
Snowmass, CO, 25 June-12 July, 1996.]


title: The Phases of QCD

abstract:
  In the recent years we have learned that light quarks play a crucial role in
QCD-like theories, transforming it to many different phases. We review what is
known about them, both from lattice and non-lattice approaches. A particularly
simple mechanism of the QCD chiral restoration phase transition is discussed
first: it suggests that it is a transition from randomly placed tunneling
events (instantons) at low T to strongly localized tunneling-anti-tunneling
pairs at high T. Many features of the transition found on the lattice can be
explained in this simple picture. Very relevant for RHIC, this approach
predicts a strong non-perturbative interaction between quarks $above$ the phase
transition. It also predicts that QGP-like phase sets in at $zero$ temperature,
provided few more light quark flavors are added to QCD. Finally, we also
discuss possible experimental signatures of the QCD phase transition. One issue
is CERN dilepton data, possibly related with ``dropping'' masses of $\rho, A_1$
mesons. Another is direct manifestation of a $softeness$ of EOS (smallness of
pressure/energy density) in the phase transition region in flow and even the
global lifetime of the system.


title:
A 3+1 Dimensional Light-Front Model with Spontaneous Breaking of Chiral
  Symmetry

abstract:
  We investigate a 3+1 dimensional toy model that exhibits spontaneous
breakdown of chiral symmetry, both in a light-front (LF) Hamiltonian and in a
Euclidean Schwinger-Dyson (SD) formulation. We show that both formulations are
completely equivalent --- provided the renormalization is properly done. For
the model considered, this means that if one uses the same transverse momentum
cutoff on the SD and LF formulations then the vertex mass in the LF calculation
must be taken to be the same as the current quark mass in the SD calculation.
The kinetic mass term in the LF calculation is renormalized non-trivially,
which is eventually responsible for the mass generation of the physical fermion
of the model.


title: Colour Coherence in Photon Induced Reactions

abstract:
  Colour coherence in hard photoproduction is considered using the Monte Carlo
event generators PYTHIA and HERWIG. Significant effects in the parton shower
are found using multijet observables for direct and resolved photon induced
reactions. The particle flow in the interjet region of direct processes shows a
strong influence of string fragmentation effects.


title: Heavy Baryon Spin 3/2 Theory and Radiative Decays of the Decuplet

abstract:
  We study the radiative decays of the decuplet $(3/2 \to 1/2 \gamma)$ using
Heavy Baryon Chiral Perturbation Theory (HBChPT). We emphasize the problems
faced by the interacting spin 3/2 field theory. We argue that, to lowest order
in the $1/m$ expansion, HBChPT provides a framework where R-invariance and the
appropiated constraints for the interacting spin 3/2 fields are consistently
incorporated. We perform a gauge invariant calculation of the decay amplitudes,
to lowest order in $1/m$ and to order $w^2/\Lambda^2_\chi$ in the chiral
expansion and report analytical results for the one-loop contributions to the
two form factors involved in the $3/2 \to 1/2 \gamma$ transitions. Parameters
independent predictions for the SU(3) forbidden decays are presented.


title: Might Fast B-Violating Transitions Be Found Soon?

abstract:
  We claim that there might exist a new interaction leading to very fast
baryon-number violating processes quite observable in the laboratory
conditions, provided all three generations are simultaneously involved.


title: A Skyrmion Fluid

abstract:
  A fluid of Skyrmions coupled to the dilaton field and the $\o$ meson field is
considered. A mean field theory is developed in which the dilaton and the $\o$
field acquire a mean value determined by the Skyrmions. The influence of the
background fields on the Skyrmion profile is determined and consequently the
scaling properties of the Skyrmion follow. The model obeys chiral invariance
and scale invariance broken only by the dilaton trace anomaly potential. The
dilaton plays the role of the scalar field as in the $\s + \o$ model. The
dilaton potential is augmented by terms that do not spoil the trace anomaly
while allowing a fit to nuclear matter properties. The phase diagram of the
model shows unique features, like a lack of solutions for certain densities and
temperatures, signalling the appearance of a new phase that can not be
described in terms of Skyrme baryons.


title: Fixed-Order QCD Backgrounds to BFKL Dynamics in Forward Jet Production

abstract:
  The production of forward jets of transverse momentum $p_T(j)\approx Q$ and
large momentum fraction $x_{jet}\gg x$ probes the onset of BFKL dynamics at
HERA. A full ${\cal O}(\alpha_s^2)$ calculation of the inclusive forward jet
cross section is presented and compared to the expected BFKL cross section.


title: Breakdown of the Hard Thermal Loop expansion near the light-cone

abstract:
  We discuss the bremsstrahlung production of soft real and virtual photons in
a quark-gluon plasma at thermal equilibrium beyond the Hard Thermal Loop (HTL)
resummation. The physics is controlled by the ratio $Q^2/q_0^2$ of the
virtuality to the energy. When $Q^2/q_0^2$ is much smaller than $g^2$, where
$g$ is the strong coupling constant, the emission rate is enhanced by a factor
$1/g^2$ over the HTL results due to light-cone singularities and the
bremsstrahlung is induced by scattering of the quark via both transverse and
longitudinal soft gluon exchanges. When $Q^2/q_0^2$ increases, the enhancement
factor is given by $q_0^2/Q^2$. When this ratio is near unity, the
bremsstrahlung contribution is of the same order as the rate predicted by the
HTL resummation. In that case, the bremsstrahlung is induced by both soft and
hard gluon exchanges.


title: What Becomes of Vortices in Theories with Flat Directions

abstract:
  In many theories with flat directions of scalar potential, static vortex
solutions do not exist for a generic choice of vacuum. In two Euclidean
dimensions, we find their substitutes --- constrained instantons consisting of
compact core formed by Abrikosov--Nielsen--Olesen vortex and long-ranged cloud
of modulus field. In (3+1) dimensions, an initial compact configuration of
string topology evolves in such a way that at every point in space the modulus
relaxes, in a universal manner, to one and the same value characteristic to the
theory.


title:
Heavy quarkonia mass-splittings in QCD: test of the $1/m$-expansion and
  estimates of $<\alpha_s G^2>$ and $\alpha_s$

abstract:
  I present a more refined analysis of the mass-splittings between the
different heavy quarkonia states, using {\it new double ratios} of exponential
moments of different two-point functions. Then, I test the validity of the
$1/m$-expansion, extract $\alpha_s(M_Z)=0.127\pm 0.011$ from $M_{\chi_c(P^1_1)}
- M_{\chi_c(P^3_1)}$, and provide a new estimate of the gluon condensate from
$M_\psi -M_{\eta_c}$ and $M_{\chi_b}-M_\Upsilon$, which combined with the
recent estimate from the $\tau$-like decay sum rules in $e^+e^-\rar I=1$
hadrons data, leads to the {\it update average value} $\la\alpha_s G^2\ra =
(7.1\pm 0.9)\times 10^{-2}$ GeV$^4$ from the light and heavy quark systems. I
also find $M_{\Upsilon}-M_{\eta_b}\approx 63^{-29}_{+51}$ MeV implying the
possible observation of the $\eta_b$ in the $\Upsilon$-radiative decay.


title: Bounds on the Z\gamma\gamma couplings from HERA

abstract:
  The possibility of testing trilinear neutral gauge boson couplings in
radiative neutral current scattering at HERA is analyzed using a Monte Carlo
program that includes the Standard Model at tree level and the anomalous
vertices. Acceptance and isolation cuts are applied as well as optimized cuts
to enhance the signal from new physics. The bounds on Z\gamma\gamma couplings
that can be achieved are not so stringent as present bounds, even for high
luminosities, but probe a different kinematical region almost unsensitive to
form factors.


title: Quarkonium Production and Color Deconfinement in Nuclear Collisions

abstract:
  The suppression of quarkonium production in nucleus-nucleus collisions was
originally proposed as a signal of colour deconfinement. Strong ``anomalous"
J/\psi suppression in Pb-Pb collisions has been reported at this Conference by
the NA50 Collaboration. Is this suppression really anomalous? Can we conclude
that the quark-gluon plasma is already discovered? What has to be done next? I
address these questions basing on the current theoretical understanding of
quarkonium production and new precise experimental information.


title: Recent Lattice Results on the Light Quark Masses

abstract:
  I discuss old and new determinations of the light quark masses using lattice
QCD. Most lattice results using various approximations can be fit together in a
simple picture which is consistent with lower values than conventionally
supposed: in the quenched approximation for the strange quark mass in the MS
bar scheme, m_s(2 GeV) = 95 (16) MeV, and for the average of the u and d quark
masses, m_l(2 GeV) = 3.6 (6) MeV. An estimate of the effects of light quark
loops yields answers lower still: m_s(2 GeV) in the range 54 - 92 MeV, and
m_l(2 GeV) in the range 2.1 - 3.5 MeV.


title: The self-penguin contribution to $K \to 2 \pi$

abstract:
  We consider the contribution to $K \rightarrow 2 \pi$ decays from the
non-diagonal $s \ra d$ quark transition amplitude. First, we calculate the most
important part of the $s \rightarrow d$ transition, the so-called self-penguin
amplitude $\sim G_F \alpha_s$, including the heavy top-quark case. Second, we
calculate the matrix element of the $s \rightarrow d$ transition for the
physical $K \rightarrow 2 \pi$ process. This part of the analysis is performed
within the Chiral Quark Model where quarks are coupled to the pseudoscalar
mesons. The CP-conserving self-penguin contribution to $K \rightarrow 2\pi$ is
found to be negligible. The obtained contribution to $\epsilon'/\epsilon$ is
sensitive to the values of the quark condensate $<\bar{q} q>$ and the
constituent quark mass $M$. For reasonable values of these quantities we find
that the self-penguin contribution to $\epsilon'/\epsilon$ is 10-15% of the
gluonic penguin contribution and has the same sign. Given the large
cancellation between gluonic and electroweak penguin contributions, this means
that our contribution is of the same order of magnitude as $\epsilon'/\epsilon$
itself.


title: Physical Anomalous Dimensions at Small $x$

abstract:
  I present a theoretical discussion of the uncertainties related to the QCD
analysis of the proton structure function $F_2(x,Q^2)$ at small $x$. The role
played by the `unphysical' gluon density is pointed out. It is shown how the
study of more observables can reduce the theoretical uncertainty and, in
particular, an alternative method of analysis, based on the introduction of
physical anomalous dimensions, is suggested.


title: Gauge invariance on bound state energy levels

abstract:
  In this paper the problem of the gauge in a bound state calculation is
discussed. In particular, in order to verify the gauge invariance in the energy
levels expansion, some set of gauge invariant contributions are given.


title:
Variational Quark Mass Expansion and the Order Parameters of Chiral
  Symmetry Breaking

abstract:
  We investigate in some detail a "variational mass" expansion approach,
generalized from a similar construction developed in the Gross-Neveu model, to
evaluate the basic order parameters of the dynamical breaking of the $SU(2)_L
\times SU(2)_R$ and $SU(3)_L \times SU(3)_R$ chiral symmetries in QCD. The
method starts with a reorganization of the ordinary perturbation theory with
the addition of an arbitrary quark mass $m$. The new perturbative series can be
summed to all orders thanks to renormalization group properties, with specific
boundary conditions, and advocated analytic continuation in $m$ properties. In
the approximation where the explicit breakdown of the chiral symmetries due to
small current quark masses is neglected, we derive ansatzes for the dynamical
contribution to the "constituent" masses $M_q$ of the $u,d,s$ quarks; the pion
decay constant $F_\pi$; and the quark condensate $< \bar q q > $ in terms of
the basic QCD scale $\Lambda_{\bar{MS}} $. Those ansatzes are then optimized,
in a sense to be specified, and also explicit symmetry breaking mass terms can
be consistently introduced in the framework. The obtained values of $F_\pi$ and
$M_q$ are roughly in agreement with what is expected from other
non-perturbative methods. In contrast we obtain quite a small value of $|< \bar
q q >|$ within our approach. The possible interpretation of the latter results
is briefly discussed.


title:
On the infrared sensitivity of the longitudinal cross section in $e^+
  e^-$ annihilation

abstract:
  We have calculated the contributions proportional to
$\beta_0^n\alpha_s^{n+1}$ to the longitudinal fragmentation function in
$e^+e^-$ annihilation to all orders of perturbation theory. We use this result
to estimate higher-order perturbative corrections and nonperturbative
corrections to the longitudinal cross section $\sigma_L$ and discuss the
prospects of determining $\alpha_s$ from $\sigma_L$. The structure of infrared
renormalons in the perturbative expansion suggests that the longitudinal cross
section for hadron production with fixed momentum fraction $x$ receives
nonperturbative contributions of order $1/(x^2Q^2)$, whereas the total cross
section has a larger, $1/Q$ correction. This correction arises from very large
longitudinal distances and is related to the behaviour of the Borel integral
for the cross section with fixed $x$ at large values of the Borel parameter.


title: Searches for Scalar and Vector Leptoquarks at Future Hadron Colliders

abstract:
  The search reaches for both scalar($S$) and vector($V$) leptoquarks at future
hadron colliders are summarized. In particular we evaluate the production cross
sections of both leptoquark types at TeV33 and LHC as well as the proposed 60
and 200 TeV colliders through both quark-antiquark annihilation and gluon-gluon
fusion: $q \bar q, gg \to SS,VV$. Experiments at these machines should easily
discover such particles if their masses are not in excess of the few TeV range.
[To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New
Directions for High Energy Physics-Snowmass96, Snowmass, CO, 25 June-12 July,
1996.]


title: Quarkonium Production At $Z^0$ and in $\Upsilon(1S)$ Decay

abstract:
  The conventional color-singlet model was challenged by the recent data on
quarkonium production. Discrepancies in production rates were observed at the
Tevatron, at LEP, and in fixed-target experiments. The newly advocated
color-octet mechanism provides a plausible solution to the anomalous quarkonium
production observed at the Tevatron. The color-octet mechanism should also
affect other quarkonium production channels. In this paper we will summarize
the studies of quarkonium production in $Z^0$ and $\Upsilon$ decays.


title: Electric-Magnetic Duality and the Heavy Quark Potential

abstract:
  We use the assumption of electric-magnetic duality to express the heavy quark
potential in QCD in terms of a Wilson Loop $W_{eff}(\Gamma)$ determined by the
dynamics of a dual theory which is weakly coupled at long distances. The
classical approximation gives the leading contribution to $W_{eff}(\Gamma)$ and
yields a velocity dependent heavy quark potential which for large $R$ becomes
linear in $R$, and which for small $R$ approaches lowest order perturbative
QCD. The corresponding long distance interaction between color magnetic
monopoles is governed by a Yukawa potential. As a consequence the magnetic
interaction between the color magnetic moments of the quarks is exponentially
damped. The semi-classical corrections to $W_{eff}(\Gamma)$ due to fluctuations
of the classical flux tube should lead to an effective string theory free from
the conformal anomaly.


title: Precision Data and Implications on the Parameters of TC theory

abstract:
  Assuming that the actual values of $m_t$ and the data set ($\Gamma_b$,
$\Gamma_h$, $\Gamma_Z$, $R_b$, $R_c$, $R_l$) are within their $1-\sigma$ errors
as reported by CDF, D0 and by LEP Collaborations, the parameter
$\Delta^{new}_b$ which measures the nonoblique corrections on the
$Zb\overline{b}$ vertex from new physics can be determined experimentally.
According to the precision data one can obtain updated constraints on the
parameters $\xi$ and the masses of the charged PGBs.


title:
Study on the rare radiative decay $B_c \to D_s^*\gamma$ in the standard
  model and multiscale walking technicolor model

abstract:
  Applying the perturbative QCD ( PQCD ) method, we study the decay
$B_c\rightarrow D_s^*\gamma$ in the standard model and multiscale walking
technicolor model. In the SM, we find that the contribution of weak
annihilation is more important than that of the electromagnetic penguin. The
presence of Pseudo-Goldstone-Bosons in the MWTCM leads to a large enhancement
in the rate of $B_c\rightarrow D_s^*\gamma$, but this model is in conflict with
the branching ratio of $Z\rightarrow b\overline b$ ( $R_b$ ) and the CLEO data
on the branching ratio BR ( $b\rightarrow s\gamma$ ). If topcolor is further
introduced, the calculated results in the topcolor assisted MWTCM can be
suppressed and be in agreement with the CLEO data for a certain range of the
parameters.


title:
A study on the rare radiative decay $B_c \to D_s^*\gamma$ in technicolor
  with scalars

abstract:
  Applying the perturbative QCD (PQCD), we study the process $B_c\rightarrow
D_s^*\gamma$ in the technicolor with a massless scalar doublet model (TCMLSM)
recently presented by C. D. Carone and H. Georgi; and compare the results with
that estimated in the standard model (SM). There are two mechanisms which
contribute to the $B_c\rightarrow D_s^* \gamma$ process. One proceeds through
the short distance $b\rightarrow s \gamma$ transition, the other through weak
annihilation accompanied by a photon emission. In the SM, these two processes
are found to contribute with the same order of magnitude. In the TCMLSM, the
modification of $B_c\rightarrow D_s^*\gamma$ from $\pi_p$ (the physical pions
in this model) is small for the allowed mass of $\pi_p$.


title:
Prompt photon, Drell-Yan and Bethe-Heitler processes in hard
  photoproduction

abstract:
  We present prospects and requirements for the study at HERA of hard photon
processes which generate high $p_T$ photons in the final state, and processes
which generate Drell-Yan lepton pairs.


title: Jet Production in Deep Inelastic Scattering at Next-to-Leading Order

abstract:
  NLO corrections to jet cross sections in DIS at HERA are studied, with
particular emphasis on the two jet final state. High jet transverse momenta are
a good criterion for the applicability of fixed order perturbation theory. A
``natural'' scale choice is the average $k_T^B$ of the jets in the Breit frame,
which suggest analyzing the data in different $<k_T^B>$ intervalls.


title: Why Are Renormalons Always In The Same Place ?

abstract:
  In order that current and future renormalon results in QCD can be used to
their full advantage it is important to understand how the Borel transforms of
related functions are themselves related. For example, a change of
renormalisation scheme can involve the inversion of a function; how is the
transform of a function related to the transform of an inverse ? We outline a
method of extracting the dominant behaviour of the Borel transform after the
action of simple operations on the function.


title: Constraining Almost Degenerate Three-Flavor Neutrinos

abstract:
  We discuss constraints on a scenario of almost degenerate three-flavor
neutrinos imposed by the solar and the atmospheric neutrino anomalies, hot dark
matter, and neutrinoless double $\beta$ decays. It is found that in the
Majorana version of the model the region with relatively large $\theta_{13}$ is
favored and a constraint on the CP violating phases is obtained.


title: Deep Inelastic Structure Functions in a Covariant Spectator Model

abstract:
  Deep-inelastic structure functions are studied within a covariant scalar
diquark spectator model of the nucleon. Treating the target as a two-body bound
state of a quark and a scalar diquark, the Bethe-Salpeter equation (BSE) for
the bound state vertex function is solved in the ladder approximation. The
valence quark distribution is discussed in terms of the solutions of the BSE.


title: Baryon Structure and the Chiral Symmetry of QCD

abstract:
  Beyond the spontaneous chiral symmetry breaking scale light and strange
baryons should be considered as systems of three constituent quarks with an
effective confining interaction and a chiral interaction that is mediated by
the octet of Goldstone bosons (pseudoscalar mesons) between the constituent
quarks.


title:
Phenomenology of Two Higgs Doublet Models with Flavor Changing Neutral
  Currents

abstract:
  A comprehensive phenomenological analysis of a two Higgs doublet model, with
flavor changing scalar currents at the tree level, called model III, is
presented. Constraints from existing experimental information especially on
(Delta F)=2 processes are systematically incorporated. Constraints emerging
from rare B-decays, Z-->b\bar b, and the \rho parameter are also examined.
Experimental implications for e^+e^- (\mu^+\mu^-)-->t\bar c+\bar t c,
t-->c\gamma(Z,g), D^0-\bar D^0, and B^0_s-\bar B^0_s oscillations, and for
e^+e^-(Z)-->b\bar s+s\bar b are investigated and experimental effort towards
these is stressed. We also emphasize the importance of clarifying the
experimental issues pertaining to Z-->b\bar b.


title: Flavor Changing Neutral Currents and the third family

abstract:
  We investigate the possibility of having sizable effects from flavor changing
neutral currents at the tree level in a particular class of Two Higgs Doublet
Models. Constraints from existing experimental information are discussed. Some
interesting signals at the future generation of lepton colliders are
illustrated.


title: Hadro-Production of Quarkonia in Fixed Target Experiments

abstract:
  In this talk I review the recent progress made in the calculations of
quarkonia production in fixed target experiments. NRQCD organizes the
calculations in a systematic expansion in $\alpha_s$ and $v$, the relative
velocity between the heavy quarks. Within this formalism there are octet
contributions which are not included in the color singlet model. These
contributions depend upon unknown matrix elementsof local operators which are
fit to the data. Using these fits, there are several predictions which do
indeed improve agreement with the data. However, the prediction for the
polarization of the produced states as well as the ratio of the $\chi_1$ to
$\chi_2$ cross sections differ substantially from the data for the case of pion
beams. Possible large corrections from higher twist effects are discussed as is
the issue of the the proper choice of masses.


title: The Hard Gluon Component of the QCD Pomeron

abstract:
  We argue that deep-inelastic diffractive scaling provides fundamental insight
into the QCD Pomeron. The logarithmic scaling violations seen experimentally
are in conflict with the scale-invariance of the BFKL Pomeron and with
phenomenological two-gluon models. Instead the Pomeron appears as a single
gluon at short-distances, indicating the appearance of a Super-Critical phase
of Reggeon Field Theory. That the color compensation takes place at a longer
distance is consistent with the Pomeron carrying odd color charge parity.


title: Multiscale Technicolor and $b \to s \gamma$

abstract:
  Correction to the $b\rightarrow s\gamma$ branching ratio in the multiscale
walking technicolor model (MWTCM) is examined. For the original MWTCM, the
correction is too large to explain the recent CLEO data. We show that if
topcolor is further introduced, the branching ratio in the topcolor assisted
MWTCM can be in agreement with the CLEO data for a certain range of the
parameters.


title: A Crucial Test for Color-Octet Production Mechanism in Z^0 Decays

abstract:
  The direct production rates of $D$-wave charmonia in the decays of $Z^0$ is
evaluated. The color-octet production processes $Z^0\rightarrow ^3D_J(c\bar c)
q\bar q$ are shown to have distinctively large branching ratios, the same order
of magnitude as that of $J/\psi$ prodution, as compared with other $D$-wave
charmonium production mechanisms. This may suggest a crucial channel to test
the color-octet mechanism as well as to observe the $D$-wave charmonium states
in $Z^0$ decays. In addition, a signal for the $^3D_J$ charmonium as strong as
$J/\psi$ or $\psi^\prime$ with large transverse momentum at the Tevatron should
also be observed.


title: 1P1 charmonium production at the Tevatron

abstract:
  The production of the ${}^1P_1$ charmonium state, $h_c$, at large-$p_T$ at
the Tevatron is considered. The colour-octet contributions to this state are
found to be dominant and give a reasonably large rate for the production of
$h_c$. This should make it feasible to look for this resonance in the $J/\psi
+\pi$ decay channel. This production rate is a prediction of NRQCD, and the
observation of the $h_c$ at the Tevatron can, therefore, be used as a test of
the colour-octet predictions of NRQCD.


title: Radiatively induced light right-handed stop

abstract:
  A right-handed stop not much heavier or even lighter than the Z boson has
today desirable phenomenological consequences. We study how it can result
within the usual radiative scenario of electroweak symmetry breaking. A
restriction on the gaugino mass parameters, M_2 < 0.3 m_10, arises if soft
terms satisfy relations suggested by unification theories. Moreover, requiring
to get a light stop without unnatural fine-tunings below the per-cent level, we
obtain another more interesting upper bound on the chargino mass, M_chargino <
M_Z, and we derive interesting conclusions about the masses of the gluino, M_3
\sim (150-300) GeV, of the heavy stop, M_stop \sim (250-500) GeV, and of the
left/right mixing angle in the stop sector, |\theta_stop| < 0.3.


title: Thermal and Chemical Equilibration in Relativistic Heavy Ion Collisions

abstract:
  We investigate the thermalization and the chemical equilibration of a parton
plasma created from Au+Au collision at LHC and RHIC energies starting from the
early moment when the particle momentum distributions in the central region
become for the first time isotropic due to longitudinal cooling. Using the
relaxation time approximation for the collision terms in the Boltzmann
equations for gluons and for quarks and the real collision terms constructed
from the simplest QCD interactions, we show that the collision times have the
right behaviour for equilibration. The magnitude of the quark (antiquark)
collision time remains bigger than the gluon collision time throughout the
lifetime of the plasma so that gluons are equilibrating faster than quarks both
chemically and kinetically. That is we have a two-stage equilibration scenario
as has been pointed out already by Shuryak sometimes ago. Full kinetic
equilibration is however slow and chemical equilibration cannot be completed
before the onset of the deconfinement phase transition assumed to be at
$T_c=200$ MeV. By comparing the collision entropy density rates of the
different processes, we show explicitly that inelastic processes, and
\emph{not} elastic processes as is commonly assumed, are dominant in the
equilibration of the plasma and that gluon branching leads the other processes
in entropy generation. We also show that, within perturbative QCD, processes
with higher power in \alpha_s need not be less important for the purpose of
equilibration than those with lower power. The state of equilibration of the
system has also a role to play. We compare our results with those of the parton
cascade model.


title: Pion interferometry with higher-order cumulants

abstract:
  We have measured second- and third-order cumulants in UA1 data ($\bar pp$
collisions at 630 GeV/c). Rather than quoting numerical values for source
parameters, we have used these in three checks to test the ``quantum
statistics'' theory for consistency over these cumulants. In the process, we
have found a method for folding theoretical correlation functions with
experimental one-particle distributions. Our preliminary results appear to
indicate that, for the specific tests performed, the data contradicts the
theory.


title:
On the Matrix Element of the Transverse Component of Bilocal Vector
  Current and its Parton Interpretation

abstract:
  In this paper we study the matrix element of the transverse component of the
bilocal vector current in the context of deep inelastic scattering. BJL limit
of high energy amplitudes together with light-front current algebra imply the
same parton interpretation for its matrix element as that of the plus
component. On the other hand, the transverse component depends explicitly on
the gluon field operator in QCD, appears as "twist three" and hence its matrix
element has no manifest parton interpretation. In this paper we perform
calculations in light-front time-ordering perturbative QCD for a dressed quark
target to order $\alpha_s$ and demonstrate that the matrix element of the
transverse component of the bilocal vector current has the same parton
interpretation as that of the plus component.


title:
Electric charge quantisation from gauge invariance of a Lagrangian: A
  catalogue of baryon number violating scalar interactions

abstract:
  In gauge theories like the standard model, the electric charges of the
fermions can be heavily constrained from the classical structure of the theory
and from the cancellation of anomalies. There is however mounting evidence
suggesting that these anomaly constraints are not as well motivated as the
classical constraints. In light of this we discuss possible modifications of
the minimal standard model which will give us complete electric charge
quantisation from classical constraints alone. Because these modifications to
the standard model involve the consideration of baryon number violating scalar
interactions, we present a complete catalogue of the simplest ways to modify
the standard model so as to introduce explicit baryon number violation. This
has implications for proton decay searches and baryogenesis.


title: In-Medium Pion Properties from Chiral Perturbation Theory

abstract:
  Two-point functions related to the pion weak decay constant $f_\pi$ are
calculated from the generating functional of chiral perturbation theory in the
mean field approximation and the heavy-baryon limit. The aim is to demonstrate
that Lorentz invariance is violated in the presence of background matter. This
fact manifests itself in the splitting of both $f_\pi$ and the pion mass into
uncorrelated time- and space-like parts. We emphasize the different in-medium
renormalizations of the correlation functions, show the inequivalence between
the in-medium values of $f_\pi$ deduced from Walecka-type models, on the one
hand, and QCD sum rules, on the other hand, and elaborate on the importance for
some nuclear physics observables.


title: The Problem of Asymptotic Freedom

abstract:
  There is a growing body of evidence that the running of $\alpha_s$ predicted
by perturbation (PT) theory is not correctly describing the accelerator
experiments at the highest energies. A natural explanation is provided by the
authors' 1992 proposal that in fact the true running predicted by the
nonperturbatively defined lattice QCD is different, leading to an ultraviolet
fixed point near $\alpha_s=.1$. It is explained how this can be understood from
the fact that the conventional perturbative method is ambiguous and does not
provide the correct asymptotic expansion. It is pointed out that there is a
large amount of lattice data that are supporting this scenario rather than the
conventional one.


title: On the origin of the rise of $F_2$ at small $x$

abstract:
  We show that, provided that the non-perturbative input is regular at the
right of the $\omega=0$ singularity of the dominant DGLAP anomalous dimension,
the rise of $F_2$ at small $x,$ experimentally measured by the averaged
observable $\lambda = <(\partial ln F_2)/(\partial ln 1/x)>,$ is
input-independent in the perturbative $Q^2$ regime at small $x$. $(\partial ln
xF)/(\partial ln Q^2)$ appears to be more input-dependent in the same range.
The GRV-type parametrisations verify these properties. Other models, namely the
BFKL kernel(QCD dipoles), DGLAP(hard pomeron singularity) give different
predictions for $\lambda$. At moderate $Q^2,$ there is a possibility of
distinguishing these different perturbative QCD predictions in the near future.


title:
Stochastic vacuum model and dual theory: a comparison in the context of
  the heavy quarkonia potential

abstract:
  The $Q \bar{Q}$ semirelativistic interaction in QCD can be expressed in terms
of the Wilson loop and its functional derivatives. In this framework we discuss
the complete (velocity and spin dependent) $1/m^2$ potential in the stochastic
vacuum model and in the dual theory.


title: Gluino signals in 4jet events and vertex tagging at LEP1

abstract:
  Heavy flavour tagging provides a broad range of possibilities in testing QCD
features at LEP. We present here a study of 4jets events at LEP I where the
so-called light gluinos could be directly produced. We show that microvertex
techniques offer a unique chance to exploit simple kinematical distributions in
order to optimise the signal coming from gluino production with respect to the
background of ordinary QCD events. Our results indicate that experimental
analyses along the lines suggested here can exclude or reveal the presence of a
gluino for masses up to 10 GeV and lifetimes below 10$^{-9}$ sec. We also point
out that a large fraction of gluino events could decay in configurations
carrying large missing energy, so to escape the usual selection criteria of
4jet samples. In our study, mass effects of quarks and gluinos have been taken
into account exactly. Our results are independent from both the jet algorithm
and its resolution parameter.}


title: Hard Processes on Nuclear Targets in QCD

abstract:
  We calculate the A-dependence of open charm and beauty as well as Drell-Yan
pair production cross sections on nuclear targets taking into account the
difference of quark and gluon distributions in free and bound nucleons. The
results are presented for both proton-nucleus and nucleus-nucleus collisions.
For the case of heavy flavour production at comparatively low energies, if
$\sigma \sim A^{\alpha}$, the values of $\alpha$ are slightly higher than
unity. With increasing energy $\alpha$ decreases in all cases and becomes
smaller than unity. We also show $\alpha$ as a function of Feynman-$x$ of the
produced $Q\overline{Q}$ or $l^+l^-$ pair and obtain that it decreases
significantly in the beam fragmentation region. The sensitivity of our results
to the used set of parton distributions is also discussed.


title: Electroweak and Flavor Dynamics at Hadron Colliders--I

abstract:
  This is the first of two reports cataloging the principal signatures of
electroweak and flavor dynamics at $\pbarp$ and $pp$ colliders. Here, we
discuss some of the signatures of dynamical elecroweak and flavor symmetry
breaking. The framework for dynamical symmetry breaking we assume is
technicolor, with a walking coupling $\alpha_{TC}$, and extended technicolor.
The reactions discussed occur mainly at subprocess energies $\sqrt{\hat s}
\simle 1 TeV$. They include production of color-singlet and octet technirhos
and their decay into pairs of technipions, longitudinal weak bosons, or jets.
Technipions, in turn, decay predominantly into heavy fermions. This report will
appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions
for High Energy Physics (Snowmass 96).


title: Electroweak and Flavor Dynamics at Hadron Colliders--II

abstract:
  This is the second of two reports cataloging the principal signatures of
electroweak and flavor dynamics at $\pbarp$ and $pp$ colliders. Here, we
complete our overview of technicolor with a discussion of signatures specific
to topcolor-assisted technicolor. We also review signatures of flavor dynamics
associated with quark and lepton substructure. These occur in excess production
rates for dijets and dileptons with high $E_T$ and high invariant mass. An
important feature of these processes is that they exhibit fairly central
angular and rapidity distributions. This report will appear in the Proceedings
of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics
(Snowmass 96).


title: Confinement and Entropy in Heavy Ion Collisions

abstract:
  We introduce a kinetical description of the hadronization of semi-deconfined
quark matter produced in heavy ion collisions. A minimal microscopic model is
considered in which the produced quarks and anti-quarks are redistributed into
hadrons according to the additive quark model. Assuming thermalized quark
matter and hadron matter we determine the appropriate parameters to describe
the properties of both matter before and after hadronization. We find an
adiabatic hadronization.


title: Particle Dark Matter

abstract:
  There is plenty of evidence that most matter in the Universe is dark
(non-luminous). Particle physics offers several possible explanations. In this
talk I focus on cold dark matter; the most promising candidates are then axions
and the lightest supersymetric particle. I briefly summarize estimates of the
present relic density of these particles, and describe efforts to detect them


title:
Anomalous dimensions of operators in polarized deep inelastic scattering
  at O(1/N_f)

abstract:
  Critical exponents are computed for a variety of twist-2 composite operators,
which occur in polarized and unpolarized deep inelastic scattering, at leading
order in the 1/N_f expansion. The resulting d-dimensional expressions, which
depend on the moment of the operator, are in agreement with recent explicit two
and three loop perturbative calculations. An interesting aspect of the critical
point approach which is used, is that the anomalous dimensions of the flavour
singlet eigenoperators, which diagonalize the perturbative mixing matrix, are
computed directly. We also elucidate the treatment of gamma^5 at the fixed
point which is important in simplifying the calculation for polarized
operators. Finally, the anomalous dimension of the singlet axial current is
determined at O(1/N_f) by considering the renormalization of the anomaly in
operator form.


title: An estimate of the QCD corrections to the decay Z --> W u d

abstract:
  We present an estimate of perturbative QCD corrections to the decay $Z \to
Wu\bar d$. A simple approximate approach is described in detail. The difference
of masses of $M_Z$ and $M_W$ is used as an expansion parameter. A complete
analytical formula for a part of the corrections is also presented.


title: Physics in Charm Energy Region

abstract:
  Recent results on physics in the charm energy region are reviewed. (1) The
new data and puzzles in exclusive hadronic decays of $J/\psi$ and $\psi'$ give
new challenges to the theory of hadronic decays. (2) With the new observation
for $\xi(2230)$ and $f_0(1500)$ in $J/\psi$ radiative decays and other
experiments, the situation in searching for glueballs is encouraging, but
theoretical uncertainties related to the properties of glueballs still remain
and need to be further reduced. (3) For the prompt production of charmonium at
large transverse momentum, gluon and quark fragmentations dominate over
leading-order parton fusions. Color-singlet fragmentation is not the dominant
mechanism for $J/\psi$ and $\psi'$ production. Color-octet fragmentation seems
to be important to explain the $J/\psi$ and, in particular, the $\psi'$ excess,
but further tests are required. The mechanism of charmonium production at
fixed-target also needs studying. (4) Some theoretical and experimental results
in charmonium and open charm hadrons are also reported.


title: $R$-Parity Violation and Flavour Violation

abstract:
  The MSSM with $R$-Parity violation allows flavour changing neutral currents
through two mechanisms, directly through one loop diagrams, and indirectly
through the generation of flavour violation in the sparticle sector. We discuss
the use of these mechanisms for constraining $R$-Parity violation, and show
that the indirect mechanism parametrised in terms of the running of the soft
masses from the unification or Planck scale typically dominates previously
calculated effects. We discuss neutrino mass generation, $\mu\to e\gamma$,
$b\to s\gamma$, and $K^0-\bar K^0$ mixing as examples.


title: $B^- \to \mu^- {\bar \nu}_\mu \gamma$ and the Determination of $f_B$

abstract:
  We compute the rate of the decay $B^- \to \mu^- {\bar \nu}_\mu \gamma$ by a
QCD relativistic potential model, with the result: ${\cal B}(B^- \to \mu^-
{\bar \nu}_\mu \gamma)=0.9 \cdot 10^{-6}$. We also discuss how this decay mode
can be used to access $f_B$.


title: The negative binomial distribution in quark jets with fixed flavour

abstract:
  We show that both the multiplicity distribution and the ratio of factorial
cumulants over factorial moments for 2-jet events in e+e- annihilation at the
Z^0 peak can be well reproduced by the weighted superposition of two negative
binomial distributions, associated to the contribution of $b\bar b$ and light
flavoured events respectively. The negative binomial distribution is then
suggested to describe the multiplicity distribution of 2-jet events with fixed
flavour.


title: Background Suppression for $\mu\to e\gamma$ with Polarized Muons

abstract:
  A search for the lepton-flavor violating $\mu^{+}\rightarrow e^{+}\gamma$
decay using polarized muons is revisited in terms of suppression of the serious
background arising from an accidental coincidence between a $e^{+}$ in the
normal muon decay and a high energy photon in the radiative muon decay,
$\mu^{+} \rightarrow e^{+} \nu \overline{\nu} \gamma$. It is found that a high
energy photon in $\mu^{+} \rightarrow e^{+} \nu \overline{\nu} \gamma$ decay is
preferentially emitted parallel to the muon spin direction, similarly to
$e^{+}$ in the normal muon decay. The selective measurements of either $e^{+}$s
or photons moving antiparallel to the muon spin direction would suppress the
accidental background for $\mu^{+} \rightarrow e^{+} \gamma$ with right-handed
and left-handed $e^{+}$s respectively.


title: The Quark Structure of Light Mesons

abstract:
  We present the results of a covariant constituent quark model, based on the
Bethe-Salpeter equation, where confinement is implemented by a string like
linear potential explaining the Regge trajectories. An instanton induced quark
force explains not only the splitting and mixing of pseudoscalar mesons, but
suggest that such effects are also present in the scalar spectrum and in a
violation of the OZI rule in the decays of scalar particles into pseudoscalars.
We demonstrate that a covariant treatment that takes into account the
relativistic components in the amplitudes is of utmost importance when
describing properties of deeply bound states and/or processes at higher
momentum transfer.


title: Structure Functions

abstract:
  We summarize recent developments in the understanding of nucleon structure.
New data on F2, R and F2c, over a wide range of Q2 and x, are described.
Conventional leading twist NLO perturbative QCD gives an excellent account of
all the new data with Q2 above a GeV, leaving very little room for either
higher twists or higher logarithms. We summarize the current status of NLO
fits, and the determination of the gluon distribution and the strong coupling
constant from structure function data. Finally we consider some of the
theoretical issues raised by the new data.