title: New flavor physics in $b$ decays

abstract:
  A new $U(1)$ gauge boson coupling predominantly to the third family has been
considered in connection with recent LEP data. We consider another likely
consequence of such a gauge boson, a greatly enhanced $b$ quark decay mode, $b
\to s \nnbar$.


title: Gauge Coupling Unification Vs. Small $\alpha_s\approx0.11$

abstract:
  I present a way of reconciling gauge coupling unification in minimal
supersymmetry with small $\alpha_s(m_Z) \approx 0.11$ and discuss the ensuing
consequences.


title: Electroweak Top Quark Production at the Fermilab Tevatron

abstract:
  Top quarks can be produced from the electroweak Wtb coupling, leading to a
single top or antitop in the final state. We examine single top quark
production at the Fermilab Tevatron and calculate the cross section as a
function of top quark mass, for each of three separate production processes. We
give details of the interferences between Feynman diagrams in W-gluon fusion
and then study the effects of an anomalous (V+A) term in the Wtb coupling.
Using predictions for the next Tevatron run, we estimate the experimental
sensitivity to the CKM matrix element V_tb as a function of the strength of the
anomalous coupling.


title: Supersymmetry in the false vacuum

abstract:
  A metastable state, or a false vacuum, is not an eigenstate of the
Hamiltonian in quantum field theory. Its energy density has a non-zero
imaginary part equal to its decay width. Therefore, supersymmetry cannot be
exact in the false vacuum. We calculate the size of this effect using the path
integral approach.


title:
Large N_f methods for computing the perturbative structure of deep
  inelastic scattering

abstract:
  The large N_f self consistency method is applied to the computation of
perturbative information in the operator product expansion used in deep
inelastic scattering. The O(1/N_f) critical exponents corresponding to the
anomalous dimensions of the twist 2 non-singlet and singlet operators are
computed analytically as well as the non-singlet structure functions. The
results are in agreement with recent explicit perturbative calculations.


title: Constraints on Light Top Squark from $B^0$-$\bar{B}^0$ mixing

abstract:
  We discuss the constraints on the mass of the lighter top squark from \bbbar\
mixing in the minimal supersymmetric standard model. A light top squark whose
mass is less than half of the $Z^0$-boson mass has not yet been excluded from
direct search experiments at LEP. However, the existence of the light top
squark may exceedingly enhance \bbbar\ mixing, owing to the box diagrams
exchanging the charginos and the up-type squarks. We show that for a sizable
region of parameter space the light top squark contribution to \bbbar\ mixing
becomes the same order of magnitude as the standard $W$-boson contribution.
Taking into account the experimental results for \bbbar\ and \kkbar\ mixings,
the existence of the light top squark is excluded in an appreciable region of
the parameter space which LEP experiments have not ruled out.


title:
Probing Electroweak Symmetry Breaking Mechanism at the LHC: A Guideline
  from Power Counting Analysis

abstract:
  We formulate the equivalence theorem as a theoretical criterion for
sensitively probing the electroweak symmetry breaking mechanism, and develop a
precise power counting method for the chiral Lagrangian formulated electroweak
theories. Armed with these, we perform a systematic analysis on the
sensitivities of the scattering processes $W^\pm W^\pm \rightarrow W^\pm W^\pm$
and $q\bar{q}'\rightarrow W^\pm Z$ for testing all possible effective bosonic
operators in the chiral Lagrangian formulated electroweak theories at the CERN
Large Hadron Collider (LHC). The analysis shows that these two kinds of
processes are "complementary" in probing the electroweak symmetry breaking
sector.


title: Gluon Spin in the Nucleon

abstract:
  We study the operator description of the gluon spin contribution ($\Gamma$)
to the nucleon's spin as it is measured in deep inelastic processes. $\Gamma$
can be related to the forward matrix element of a local gluon operator in
$A^+=0$ gauge. In quark models the nucleon contains ambient color electric and
magnetic fields. The latter are thought to be responsible for spin splittings
among the light baryons. We show that these fields give rise to a significant
{\it negative\/} contribution to $\Gamma$ at the quark model renormalization
scale, $\mu_0^2$. The non-Abelian character of QCD is responsible for the sign
of $\Gamma$. In a generic non-relativistic quark model $\Gamma_{NQM}=-{8\over
9}{\alpha_{NQM}\over m_q}\langle{1\over r}\rangle$, in the bag model
$\Gamma_{bag}=-.1\alpha_{bag}$. These correspond to $\Gamma_{NQM}\approx -0.7$
and $\Gamma_{bag}\approx -0.4$ at $\alpha_{QCD}\approx 1.0$.


title: Glueballs in Peripheral Heavy-Ion Collisions

abstract:
  We estimate the cross-section for glueball production in peripheral heavy-ion
collisions through two-photon and double-Pomeron exchange, at energies that
will be available at RHIC and LHC. Glueballs will be produced at large rates,
opening the possibility to study decays with very small branching ratios. In
particular, we discuss the possibility of observing the subprocess $\gamma
\gamma (PP) \rightarrow G \rightarrow \gamma \gamma$.


title: Quark Confinement in a Random Background Gross-Neveu Model

abstract:
  We study an extended Gross-Neveu model with $N_f$ quark flavors and with an
additional SU(2) (global color) degree of freedom of the quarks. The four
fermion interaction in the color channel is mediated by a random color matrix
with fixed strength. The effective potential for the quark condensate and the
scalar correlation function is investigated in the large $N_f$-limit. Quark
anti-quark thresholds are absent in the scalar correlation function implying
that the decay of the scalar meson in free quarks is avoided. The transition
from the low energy to the high energy perturbative regime is found to be
smooth. Perturbation theory provides a good description of Green's functions at
high energies, although there is no quark liberation.


title:
NLO QCD corrections to the production of off--shell WW pairs at $e^+
  e^-$ colliders

abstract:
  QCD corrections to $e^+e^- \ra WW \ra q_1 \bar q_1 q_2 \bar q_2$ are computed
and presented in a form which allows to impose realistic cuts on the structure
of the observed events. QCD radiation substantially modifies the jet--jet
invariant mass distributions from which the value of the $W$ mass will be
extracted. When the range of allowed jet--jet masses is restricted, as it has
been proposed in order to suppress non--$WW$ backgrounds, the total cross
section is also deeply affected. If all events are forced to four jets,
combining the two partons with smallest invariant mass, and the reconstructed
masses are required to satisfy $ \left| M_{Ri} -M_W \right| \le 10$ GeV $i$=1,2
the lowest order cross section can be reduced by more than 40\%.


title: Nucleon Tensor Charges in the SU(2) Chiral Quark--Soliton Model

abstract:
  We investigate the singlet $g_T^{(0)}$ and isovector $g_T^{(3)}$ tensor
charges of the nucleon, which are deeply related to the first moment of the
leading twist transversity quark distribution $h_1(x)$, in the SU(2) chiral
quark-soliton model. With rotational $O(1/N_c)$ corrections taken into account,
we obtain $g_T^{(0)}=0.69$ and $g_T^{(3)}=1.45$ at a low normalization point of
several hundreds MeV.
  Within the same approximation and parameters the model yields
$g_A^{(0)}=0.36$, $g_A^{(3)}=1.21$ for axial charges and correct
octet--decuplet mass splitting. We show how the chiral quark-soliton model
interpolates between the nonrelativistic quark model and the Skyrme model.


title: Electromagnetic form factors of the nucleon in a covariant diquark model

abstract:
  We present a simple covariant constituent diquark-quark model for the
nucleon. The nucleon is assumed to be composed of a scalar diquark and a quark
which interact via a quark exchange. Starting from the Bethe-Salpeter equation,
the instantaneous approximation leads to a diquark-quark Salpeter equation. In
the Mandelstam formalism, the electromagnetic form factors of the nucleon are
calculated for momentum transfers up to $q^2 = - 3 \; (\mbox{GeV/c})^2$. A
remarkable description of the experimental data is obtained. Especially, the
model gives nearly the right values for the proton and (negative) neutron
charge radii, and a qualitative description of the magnetic form factors.


title:
Screening of initial parton production in ultrarelativistic heavy-ion
  collisions

abstract:
  Screening of initial parton production due to the presence of on-shell
partons in high-energy heavy-ion collisions is discussed. It is shown that the
divergent cross sections in the calculation of parton production can be
regulated self-consistently without an {\it ad hoc} cut-off, and that the
resultant parton production and transverse energy production rate are finite.
Consequences on the energy density estimates are discussed.


title:
Shadowing Corrections in Diffractive QCD Leptoproduction of Vector
  Mesons

abstract:
  The formulae for shadowing corrections in deep inelastic leptoproduction of
vector mesons are presented. These formulae are also applicable for
photoproduction of vector mesons constituted of heavy quarks. Our results are
conveniently presented by the definition of a damping factor giving the
reduction of the calculated cross sections due to shadowing. Our calculated
cross sections are compared with those obtained with no shadowing and with the
available experimental data including the recent data from HERA. We have also
investigated the importance of shadowing on the relationship between $\frac{\pa
F_2(Q^2,x)}{ \pa ln Q^2}$ and the cross section for virtual photoproduction of
vector mesons. A discussion of shadowing corrections to the proton's gluon
density is presented and numerical estimates are given.


title:
Determination of CKM phases through rigid polygons of flavor SU(3)
  amplitudes

abstract:
  Some new methods for the extraction of CKM phases $\alpha$ and $\gamma$ using
flavor SU(3) symmetry have been suggested through the construction of rigid
polygons in the complex plane with sides equal to the decay amplitudes of B
mesons into two mesons belonging to the light (charmless) pseudoscalar octet.
These rigid polygons incorporate all the possible amplitude triangles and,
being overdetermined, also serve as consistency checks and in estimating the
rates of some decay modes. The same techniques also lead to numerous useful
amplitude triangles when octet-singlet mixing has been taken into account and
nearly physical $\eta,\eta'$ are used.


title: Polarizabilities of Gluon Fields in a Polarized Nucleon

abstract: This paper has been withdrawn by the author.


title: Nucleon Helicity in Pion Photoproduction

abstract:
  Pion-photoproduction data is examined to check for the nucleon-helicity
conservation predicted by asymptotic QCD. The differential cross section shows
agreement with constituent-counting rules, and polarization data is not in
disagreement with conservation of nucleon helicity. However large uncertainties
in the polarization measurements do not allow a conclusive statement. The
helicity amplitudes from a partial-wave analysis are also examined for helicity
conservation. While the amplitudes become small as $s$ increases, the $s$
dependence of the helicity-conserving amplitudes is similar to the dependence
of the non-conserving amplitudes.


title: Soft Terms from Dilaton/Moduli sectors

abstract:
  We study the structure of the soft SUSY-breaking terms obtained from large
classes of 4-D Strings under the assumption of dilaton/moduli dominance in the
process of SUSY-breaking. In particular, we first analyze in detail the
dilaton-dominated limit because of its finiteness properties and
phenomenological predictivity, and second, we consider the new features
appearing when several moduli fields contribute to SUSY breaking. Although some
qualitative features indeed change in the multimoduli case with respect to the
dilaton dominance one, the most natural mass relations at low-energy $m_l < m_q
\simeq M_g$ are still similar. We also study the presence of tachyons pointing
out that their possible existence may be, in some cases, an interesting
advantage in order to break extra gauge symmetries. Finally, we find that the
mechanism for generating a ``$\mu $-term'' by the K\"ahler potential, as
naturally implemented in orbifolds, leads to the prediction $|tg\beta |=1$ at
the String scale, independently of the Goldstino direction. In this connection,
it is worth noticing that in the dilaton-dominated case we obtain the
remarkable result that the whole SUSY spectrum is completely determined with no
free parameters.


title: Ratios of $B$ and $D$ Meson Decay Constants in Improved Mock Meson Model

abstract:
  We calculate the ratio $f_{B_s}/f_{B_d}$ by following the Oakes' method which
is based on chiral symmetry breaking, but we improve his calculation by
performing the calculation of the factor
$<0|{\bar{b}}{\gamma}_5s|B_s>$/$<0|{\bar{b}}{\gamma}_5d|B_d>$ in the mock meson
model. In this calculation we improved the mock meson model by using the value
of the parameter $\beta$ which is obtained by the variational method in the
relativistic quark model. We also calculate $f_{D_s}/f_{D_d}$, and then
$(f_{B_s}/f_{B_d})\, /\, (f_{D_s}/f_{D_d})$. In this method we also obtain the
ratio $f_{B_s}/f_{D_s}$ and $f_{B_d}/f_{D_d}$ which are important for the
knowledge of CP violation and $B$-$\bar{B}$ mixing.


title: Lattice Results For Heavy Quark Physics

abstract:
  The status of lattice calculations for heavy quark systems is reviewed,
focussing on weak matrix elements for leptonic and semi-leptonic decays of
heavy mesons. After an assessment of the main systematic errors, results for
the decay constants $f_D$ and $f_B$, the $B$ parameter describing $B - \bar{B}$
mixing, the Isgur-Wise function and the spectroscopy of heavy baryons are
discussed.


title: Quarks, mesons and (exact) flow equations

abstract:
  Dynamical chiral symmetry breaking is described within the linear sigma model
of QCD coupled to quarks. The main technical tool used for this intrinsically
non--perturbative problem is an exact renormalization group equation for the
quantum effective action. It is demonstrated that realistic values for
phenomenological quantities like the pion decay constant, constituent quark
masses or the chiral condensate are obtainable.


title: Supersymmetric Particle Production at HERA

abstract:
  In the framework of the minimal supersymmetric standard model and the
$R$-parity breaking model, we investigate various production processes of the
supersymmetric partner at HERA energies. Our emphasis is paid upon the scalar
top quark, the partner of top quark, characterized by its lighter mass than the
top quark and other scalar quarks in a model. We propose experimentally
feasible approaches to search for clean signals of the stop from either its
production or decay processes.


title: Unified QCD evolution equations for quarks and gluons

abstract:
  Considering the BFKL and DGLAP QCD evolution equations for structure
functions, we discuss the possibility of unifying them in the whole $x$ and
$Q^2$ range. We emphasize that the main problem is related to the constraint of
angular ordering of the radiation, and the cancellation of the related
collinear singularities for inclusive processes. At the leading log\ $1/x$ and
log\ $Q^2$ level, we write down a unified system of equations satisfying this
cancellation constraint. At low $x$, it leads to a less singular behaviour of
the structure functions than the BFKL prediction.


title: Unknotting the polarized vacuum of quenched QED

abstract:
  A knot-theoretic explanation is given for the rationality of the quenched QED
beta function. At the link level, the Ward identity entails cancellation of
subdivergences generated by one term of the skein relation, which in turn
implies cancellation of knots generated by the other term. In consequence, each
bare three-loop diagram has a rational Laurent expansion in the Landau gauge,
as is verified by explicit computation. Comparable simplification is found to
occur in scalar electrodynamics, when computed in the Duffin-Kemmer-Petiau
formalism.


title:
A QCD Sum Rule Approach to the $s\to d\gamma$ Contribution to the
  $\Omega^-\to \Xi^-\gamma$ Radiative Decay

abstract:
  QCD sum rules are used to calculate the contribution of short-distance
single-quark transition $s\rightarrow d \gamma$, to the amplitudes of the
hyperon radiative decay, $\Omega^-\rightarrow \Xi^-\gamma$. We re-evaluate the
Wilson coefficient of the effective operator responsible for this transition.
We obtain a branching ratio which is comparable to the unitarity limit.


title: Classical Kinetics of Hard Thermal Phenomena in High Temperature QCD

abstract:
  Classical transport theory for colored particles is reviewed and used to
derive the hard thermal loops of QCD. A perturbative study of the non-Abelian
transport equations that preserves their gauge symmetry is used to compute the
induced color current in a hot quark-gluon plasma. From this approach the
effective action of hard thermal loops can be derived. This derivation is more
direct than alternative ones based on perturbative quantum field theory, and
shows that hard thermal effects in hot QCD are essentially classical.


title:
Decay-lepton angular distribution in polarized $e^+e^- \to \tt$ and
  $CP$-violating dipole couplings of the top quark

abstract:
  In the presence of an electric dipole coupling of $t \bar t$ to a photon, and
an analogous ``weak" dipole coupling to the $Z$, $CP$ violation in the process
$e^+e^- \rightarrow t \bar t$ leads to the polarization of the top and
anti-top. This polarization can be analyzed by studying the energy and angular
distributions of a decay charged lepton (anti-lepton) when the top (anti-top)
decays leptonically. We have obtained analytic expressions for these
distributions when either $t$ or $\overline t$ decays leptonically. We study
two types of simple $CP$-violating angular asymmetries which do not need tof
simple $CP$-violating angular asymmetries which do not need the full
reconstruction of the $t$ or $\bar t$. These together can help to determine the
electric and weak dipole form factors independently. We have also shown how the
use of longitudinal beam polarization can help to do this with only one
asymmetry measurement, and to imprhelp to do this with only one asymmetry
measurement, and to improve the sensitivity.


title: Top Quark Physics at the NLC

abstract:
  A high energy $e^+e^-$ linear collider (NLC) is an excellent tool for
studying the properties of the top quark. In this talk I review some of the
theory of top quark production and decay in $e^+e^-$ collisions both at
threshold and in the continuum. I also report on the results of
phenomenological analyses of $t\bar t$ production at the NLC.


title: Do Maxicharged particles exist?

abstract:
  The critical charge $Z_c$ is estimated for elementary particles using a
Newton-Wigner position operator inspired model. Particles with $Z \sim Z_c$
(maxicharged particles), if they exist at all, can have unusual properties
which turn them into elusive objects not easy to detect. Dirac's magnetic poles
have a (magnetic) charge $g\gg Z_c$. This gives one more argument that it is
unexpected that pointlike monopoles to be found in our world, where $
\alpha^{-1}\simeq 137$.


title: The dynamics of a thermal non-equilibrium anharmonic oscillator

abstract:
  We propose an non-standard method to calculate non-equilibrium physical
observables. Considering the generic example of an anharmonic quantum
oscillator, we take advantage of the fact that the commutator algebra of second
order polynomials in creation/annihilation operators closes. We solve the
von~Neumann equation for the density-operator exactly in the mean field
approximation and study the time evolution of the particle number and the
expectation value < X^2 > .


title: Conformal Invariance of the Transition Vertex $2 \to 4$ gluons

abstract:
  We show that the transition vertex: two reggeized gluons $\to$ four reggeized
gluons is invariant under M\"{o}bius transformations. This provides an
important step in defining a conformally invariant effective field theory for
QCD in the Regge limit.


title: Inverse-Moment Chiral Sum Rules

abstract:
  A general class of inverse-moment sum rules was previously derived by the
authors in a chiral perturbation theory (ChPT) study at two-loop order of the
isospin and hypercharge vector-current propagators. Here, we address the
evaluation of the inverse-moment sum rules in terms of existing data and
theoretical constraints. Two kinds of sum rules are seen to occur, those which
contain as-yet undetermined ${\cal O}(q^6)$ counterterms and those free of such
quantities. We use the former to obtain phenomenological evaluations of two
${\cal O}(q^6)$ counterterms. Light is shed on the important but difficult
issue regarding contributions of higher orders in the ChPT expansion.


title: Wave Packet Collisions in Yang-Mills-Higgs Theory

abstract:
  We present numerical simulations of colliding wave packets in spontaneously
broken SU(2) Yang-Mills-Higgs theory. Compared with pure Yang-Mills theory,
introducing the Higgs field leads to new aspects in the dynamics of the system.
The evolution of the gauge field and the Higgs field is investigated as a
function of the amplitude of the wave packets and of the mass ratio of the
Higgs and the gauge boson. We find regions in our parameter space in which
initial wave packets scatter into final configurations with dramatically
different momentum distributions.


title: Neutrino-less Double Beta Decay and Physics Beyond the Standard Model

abstract:
  A brief sketch is given of the present observational status and future
prospects of the physics of neutrino mass, including a survey of the various
theoretical schemes of neutrino mass generation. Emphasis is given to those
which are motivated by present experimental hints from solar and atmospheric
neutrinos, as well as from cosmological data related to the dark matter
question. The conceptual importance of neutrino-less double beta decay as a
distinctive signature of the Majorana character of neutrinos is stressed.
Barring accidental cancellations this process gives the strongest laboratory
constraint on neutrino mass.


title: SVD Approach to Data Unfolding

abstract:
  Distributions measured in high energy physics experiments are usually
distorted and/or transformed by various detector effects. A regularization
method for unfolding these distributions is re-formulated in terms of the
Singular Value Decomposition (SVD) of the response matrix. A relatively simple,
yet quite efficient unfolding procedure is explained in detail. The concise
linear algorithm results in a straightforward implementation with full error
propagation, including the complete covariance matrix and its inverse. Several
improvements upon widely used procedures are proposed, and recommendations are
given how to simplify the task by the proper choice of the matrix. Ways of
determining the optimal value of the regularization parameter are suggested and
discussed, and several examples illustrating the use of the method are
presented.


title: Color-Octet Quarkonium Production at the $Z$ Pole

abstract:
  The direct production rate of $J/\psi$ via the color-octet mechanism is
calculated at the $Z$ resonance. The color-octet production process $Z\to
J/\psi q \bar q$ is shown to have a substantial branching ratio as well as a
distinctive energy spectrum, which can be used as a powerful tool to
distinguish from the color-singlet direct production of the $J/\psi$.


title:
Buchm\"uller Scaling, the QCD Pomeron, and Tevatron Diffractive Hard
  Scattering

abstract:
  We discuss the observed scaling of the small-x diffractive and total
deep-inelastic structure functions at HERA. We argue that the parton
interpretation of Buchm\"uller and Hebecker can be understood within QCD as the
appearance of the Pomeron in a Super-Critical phase. In diffractive hard
scattering, the Pomeron appears as reggeized gluon exchange in a
color-compensating background field. The formalism can also be applied to
diffractive $W$ production at the Tevatron. If the scaling is a true asymptotic
property then it should anticipate the appearance of a further massive sector
of QCD and associated asymptotic Critical Pomeron behaviour.


title: Chiral Divergent Properties of Hadrons in the Large-N_c Limit

abstract:
  We compute the leading non-analytic correction to the baryon mass in the
combined limits m_\pi -> 0, N_c -> \infty with the product m_\pi x N_c held
fixed. We reproduce the results of Cohen and Broniowski using semiclassical
methods rather than heavy-baryon chiral perturbation theory. The calculation is
organized to demonstrate: (1) the model independence of our results; and (2)
the crucial role played by (iso)rotations of the hedgehog pion cloud
surrounding the baryon. Our rotationally improved large-N_c calculation yields
results that naturally interpolate between ordinary chiral perturbation theory
on the one hand, and large-N_c physics on the other.


title: Hard diffractive electroproduction of vector mesons in QCD

abstract:
  Hard diffractive electroproduction of longitudinally polarized vector mesons
is calculated within the leading $\alpha_s\ln{Q^2\over\Lambda_{QCD}^2}$
approximation of QCD using the leading order parton densities within the
nucleon. Novel QCD features of the production of excited states and of the
restoration of flavor symmetry are analyzed. At the onset of the asymptotic
regime, our analysis finds an important role of quark Fermi motion within the
diffractively produced vector mesons, and we suggest to use this effect to
measure the high momentum tail of the wave function of the vector mesons. We
deduce a kinematical boundary for the region of applicability of the
decomposition of the hard amplitudes over powers of $Q^2$ and/or a limit on the
increase of the cross sections of hard processes at small $x$, and briefly
analyze its consequences. We also estimate the nuclear attenuation of the
diffractive electroproduction of vector mesons and compare with estimates of
the shadowing of the longitudinal structure function.


title:
Pade Approximants, Borel Transforms and Renormalons: the Bjorken Sum
  Rule as a Case Study

abstract:
  We prove that Pade approximants yield increasingly accurate predictions of
higher-order coefficients in QCD perturbation series whose high-order behaviour
is governed by a renormalon. We also prove that this convergence is accelerated
if the perturbative series is Borel transformed. We apply Pade approximants and
Borel transforms to the known perturbative coefficients for the Bjorken sum
rule. The Pade approximants reduce considerably the renormalization-scale
dependence of the perturbative correction to the Bjorken sum rule. We argue
that the known perturbative series is already dominated by an infra-red
renormalon, whose residue we extract and compare with QCD sum-rule estimates of
higher-twist effects. We use the experimental data on the Bjorken sum rule to
extract $\alpha_s(M_Z^2) = 0.116_{-0.006}^{+0.004}$, including theoretical
errors due to the finite order of available perturbative QCD calculations,
renormalization-scale dependence and higher-twist effects.


title: Improved hard-thermal-loop effective action for hot QED and QCD

abstract:
  The conventional results for hard thermal loops, which are the building
blocks of resummed perturbation theory in thermal field theories, have
collinear singularities when external momenta are light-like. It is shown that
by taking into account asymptotic thermal masses these singularities are
removed. The thus improved hard thermal loops can be summarized by compact
gauge-invariant effective actions, generalizing the ones found by Taylor and
Wong, and by Braaten and Pisarski.


title: Effect of Initial Particle Instability in Muon Collisions

abstract:
  We study $\mu^+\mu^-$ collision with production of some state $F$ (for
example, $F= W^+$) and $(e\bar\nu)$ system with the effective mass, which is
less than muon mass. In this case the momentum $k$, transferred from $\mu$ to
$e\bar\nu$ system (virtual neutrino momentum), can be time--like. The path of
integration over $k^2$ goes through the pole at $k^2=0$. It gives divergent
cross section. This divergence disappears if the finite width $\Gamma$ of
initial $\mu$ is taken into account. It gives the factor $\propto\Gamma^{-1}$
in cross section. The compensating factor $\Gamma$ appears from $\mu\to
e\bar\nu \nu$ subprocess. The resulting cross section is finite but high
enough.


title: $SU(n)\otimes U(1)_c$ gauge models with spontaneous symmetry breaking

abstract:
  A possible generalization of the technique of the standard model to
$SU(n)\otimes U(1)$ gauge models is proposed. A special Higgs mechanism and a
new kind of Yukawa couplings in unitary gauge are introduced. These allow us to
obtain a general method of deriving boson mass spectrum and coupling
coefficients which will be used to find an exact solution of the Pisano-Pleitez
three-generation $SU(3)\otimes U(1)$ model. A new anomaly-free one-generation
model is briefly discussed.


title:
Tests of Anomalous Higgs Boson Couplings through $e^-e^+ \to HZ$ and
  $H\gamma$

abstract:
  We show how the processes $e^- e^+ \to ZH, ~ \gamma H$, which will be studied
at LEP2 and at high energy colliders, could be used to search for types of New
Physics (NP) characterized by an effective NP scale in the few TeV range and
affecting the scalar sector only. In particular, for $e^- e^+ \to Z H$, we
propose the measurement of suitable azimuthal asymmetries determined from the
angular distribution of the $Z$-decay plane with respect to the $Z$-production
one. Such asymmetries, together with the $ZH$ angular distribution, may allow a
complete disentangling of the five $dim=6$ operators $ {\cal O }_{UB}$, $ {\cal
O }_{UW}$, $\overline{{\cal O }}_{UB}$, $\overline{{\cal O }}_{UW}$, ${\cal O
}_{\Phi2}$, describing the residual NP effects to the Higgs couplings. We note
that the first four of these operators contribute to processes relevant to LEP1
precision measurements only at the 1-loop level, while the last operator
remains completely unconstrained at this level. The process $e^- e^+ \to \gamma
H$ is also very sensitive to NP and should bring important independent
information.


title: Interplay between polarized DIS and RHIC spin physics

abstract:
  The complementarity of polarized DIS experiments and polarized Proton-Proton
experiments is illustrated for two examples. It is shown how the twist-3 part
of the second moment of $g_2(x,Q^2)$ and the single-spin photon asymmetry are
connected and it is discussed how the polarized gluon distribution can be
obtained from the measurement of direct gamma asymmetries.


title: Strategy for detecting b polarization effects

abstract:
  We suggest a strategy for detecting $b$ polarization effects in $e^+e^-$
annihilation on $Z$ resonance. Using two types of inclusive leptonic samples
with different ${\Lambda_b}$ fractions in $Z \ra b\bar{b}$ events, the $b$
polarization effects may be detected without large uncertainties of $b$
fragmentation and ${\Lambda_b}$ decay model.


title: $\alpha_s(M_Z^2)$ and $R_b$ discrepancy with nonuniversal interactions

abstract:
  We implement global fits to LEP data with the \non interactions. Consistent
$R_b$ with experimental value and consistent $\as(M_Z^2)$ with that from low
energy experiments are obtained. We also find that the $\xx$ is better than the
Standard Model. And we argue that other kinds of new physics are needed to
explain the difference between the values of $\as(M_Z^2)$ from low energy
experiments and from the 3-jet ratio.


title:
Dimensional Reduction and Catalysis of Dynamical Symmetry Breaking by a
  Magnetic Field

abstract:
  It is shown that a constant magnetic field in 3+1 and 2+1 dimensions is a
strong catalyst of dynamical chiral symmetry breaking, leading to the
generation of a fermion dynamical mass even at the weakest attractive
interaction between fermions. The essence of this effect is the dimensional
reduction $D\to D-2$ in the dynamics of fermion pairing in a magnetic field.
The effect is illustrated in the Nambu--Jona--Lasinio (NJL) model and QED. In
the NJL model in a magnetic field, the low--energy effective action and the
spectrum of long wavelength collective excitations are derived. In QED (in
ladder and improved ladder approximations) the dynamical mass of fermions
(energy gap in the fermion spectrum) is determined. Possible applications of
this effect and its extension to inhomogeneous field configurations are
discussed.


title:
Inclusive Two--Jet Cross Sections in $\gamma\gamma$--Processes at
  $e^+e^-$ Colliders

abstract:
  We have calculated inclusive one-- and two--jet production in photon--photon
collisions in next--to--leading order superimposing direct, single resolved and
double resolved cross sections. The results are compared with recent
experimental data from the TOPAZ and AMY collaborations at TRISTAN. Good
agreement is found between experiment and the theoretical results.


title:
Two dimensional QCD with matter in adjoint representation: What does it
  teach us?

abstract:
  We analyse the highly excited states in $QCD_2 (N_{c}\rightarrow\infty) $
with adjoint matter by using such general methods as dispersion relations,
duality and unitarity. We find the Hagedorn-like spectrum $\rho(m) \sim
m^{-a}\exp(\beta_H m)$ where parameters $\beta_H$ and $a$ can be expressed in
terms of asymptotics of the following matrix elements $f_{n_{\{k\}}} \sim \la
0|Tr(\bar{\Psi}\Psi)^{k}|n_{k}\ra$. We argue that the asymptotical values
$f_{n_{\{k\}}}$ do not depend on $k$ (after appropriate normalization). Thus,
we obtain $\beta_H= (2/\pi)\sqrt{\pi/g^2N_{c}}$ and $a = -3/2$ in case of
Majorana fermions in the adjoint representation. The Hagedorn temperature is
the limiting temperature in this case. We also argue that the chiral condensate
$\la 0|Tr(\bar{\Psi}\Psi) |0\ra$ is not zero in the model. Contrary to the 't
Hooft model, this condensate does not break down any continuous symmetries and
can not be considered as an order parameter. Thus, no Goldstone boson appears
as a consequence of the condensation. We also discuss a few apparently
different but actually tightly related problems: master field, condensate,
wee-partons and constituent quark model in the light cone framework.


title: Gauge Coupling Unification due to Large String Threshold Corrections

abstract:
  We show that large string threshold corrections can reconcile the string and
MSSM unification scales in fermionic strings. This requires at least three
moduli with large VEVs which are different from each other and MSSM states
arising in an unconventional manner from the string spectrum. The former is
easily achieved by supersymmetry breaking by both hidden gaugino and matter
condensation whereas the latter needs to be seen in explicit string models.


title: A random matrix model for chiral symmetry breaking

abstract:
  We formulate a random matrix model which mimics the chiral phase transition
in QCD with two light flavors. Two critical exponents are calculated. We obtain
the mean field values $\beta = \frac 12 $ and $\delta = 3$. We also find that
the chiral phase transition can be characterized by the dynamics of the
smallest eigenvalue of the Dirac operator. This suggests an alternative order
parameter which may be of relevance for lattice QCD simulations.


title: Determining the Weak Phase $\gamma$ From Charged $B$ Decays

abstract:
  A quadrangle relation is shown to be satisfied by the amplitudes for $B^+ \to
\pi^0 K^+,~\pi^+ K^0,~\eta K^+$, and $\eta' K^+$. By comparison with the
corresponding relation satisfied by $B^-$ decay amplitudes, it is shown that
the relative phases of all the amplitudes can be determined up to discrete
ambiguities. Making use of an SU(3) relation between amplitudes contributing to
the above decays and those contributing to $B^{\pm} \to \pi^{\pm} \pi^0$, it is
then shown that one can determine the weak phase $\gamma \equiv {\rm Arg}
(V_{ub}^* V_{cb}/V_{us}^* V_{cs})$, where $V$ is the Cabibbo-Kobayashi-Maskawa
matrix describing the charge-changing weak interactions between the quarks
$(u,c,t)$ and $(d,s,b)$.


title: Corrections to Angular Ordering in Multiple Hadroprodroproduction

abstract:
  One of the key ideas in describing the multiparticle production at high
energies in the perturbative QCD is the angular ordering in successive
soft-gluon emission. We analyse the angular distribution of particles in a jet,
and investigate the corrections to the angular ordering. At a small angle from
the jet direction, the angular ordering is exact at the next-to-leading order.
At a large angle, the angular ordering overestimates the angular particle
density by a factor $(1-\gamma\ln \cos^2(\theta/2))$, where $\gamma$ is the
anomalous dimension of the multiplicity. The $O(\gamma)$ correction restores
the boost invariance of the cross section.


title: Large neutrino asymmetries from neutrino oscillations

abstract:
  We re-examine neutrino oscillations in the early universe. Contrary to
previous studies, we show that large neutrino asymmetries can arise due to
oscillations between ordinary neutrinos and sterile neutrinos. This means that
the Big Bang Nucleosynthesis (BBN) bounds on the mass and mixing of ordinary
neutrinos with sterile neutrinos can be evaded. Also, it is possible that the
neutrino asymmetries can be large (i.e. $\stackrel{>}{\sim} 10\%$), and hence
have a significant effect on BBN through nuclear reaction rates.


title: Subthreshold Antiproton Spectra in Relativistic Heavy Ion Collisions

abstract:
  We study the structure of antiproton spectra at extreme subthreshold
bombarding energies using a thermodynamic picture. Antiproton production
processes and final state interactions are discussed in detail in order to find
out what can be learned about these processes from the observed spectra.


title: Theoretical Review of B-Physics

abstract:
  We review several aspects of B-Physics. In particular we discuss:
  i) The theoretical framework for B-decays,
  ii) Weak decays beyond leading logarithms,
  iii) Standard analysis of the unitarity triangle,
  iv) Rare B-decays,
  v) CP violation including the issue of electroweak penguins
  vi) Future visions of this field.


title: Multiplicity and Event Shape in the Perturbative QCD

abstract:
  The multiple hadroproduction in the perturbative QCD is briefly reviewed.
There are a number of quantities which can be analysed with the use of the
high-luminosity TRISTAN data. The analysis will contribute to clarifying some
unsolved questions, and to the deeper understanding of the jet physics.


title:
Spectral functions for composite fields and viscosity in hot scalar
  field theory

abstract:
  We derive a spectral representation for the two-point Green function for
arbitrary composite field operators in Thermo Field Dynamics (TFD). A simple
way for calculating the spectral density within TFD is pointed out and compared
with known results from the imaginary time formalism. The method is applied to
hot $\phi^4$ theory. We give a compact derivation of the one-loop contribution
to the shear viscosity and show that it is dominated by low-momentum plasmons.


title: Covariant generalization of the ISGW quark model

abstract:
  A fairly general Lorentz-covariant quark model of mesons is constructed. It
has several versions whose nonrelativistic limit corresponds to the well-known
Isgur, Scora, Grinstein, and Wise model. In the heavy-quark limit, the
covariant model naturally and automatically produces the heavy-quark symmetry
results for meson decay constants and semileptonic decay form factors. The
meson decay constants and the Isgur-Wise functions are calculated for various
versions of the covariant model and compared with other estimates. A general
and adaptable structure of the covariant model ensures that it can be used to
describe transitions involving light and/or heavy mesons.


title: The Plasmon in Hot $\phi^4$ Theory

abstract:
  We study the 2-loop resummed propagator in hot $g^2\phi^4$ theory. The
propagator has a cut along the whole real axis in the complex energy plane, but
for small $g$, the spectral density is sharply peaked around the plasmon. The
dispersion relation and the width of the plasmon are calculated at zero {\em
and} finite momentum. At large momenta the spectral width vanishes, and the
plasmon looses its collectivity and behaves like a non-interacting free
particle.


title: Physics of the Quark-Gluon Plasma

abstract:
  Some features of the high temperature gluonic matter, such as the breakdown
of the fundamental group symmetry by the kinetic energy, the screening of test
quarks by some unusual gluon states and the explanation of the absence of
isolated quarks in the vacuum without the help of infinities are presented in
this talk. Special attention is paid to separate the dynamical input inferred
from the numerical results of lattice gauge theory from the kinematics.


title:
Update to the Neutrino-Electron Scattering in Left-Right Symmetric
  Models

abstract:
  In a previous paper we study the neutrino-electron scattering in the
framework of a left-right symmetric model (LRSM). Constraints on the LRSM
parameters $M_{Z_{2}}$ and $\phi$ were obtained. Based on new measurements we
present an update to these constraints and also include in the calculation the
radiative corrections.


title: Antimatter Gravity and Antihydrogen Production

abstract:
  Certain modern theories of gravity predict that antimatter will fall
differently than matter in the Earth's gravitational field. However, no
experimental tests of gravity on antimatter exist and all conclusions drawn
from experiments on matter depend, at some level, on a specific model. We have
proposed a direct measurement that would compare the gravitational acceleration
of antiprotons to that of negatively charged hydrogen ions. Substantial
progress towards the development of this experiment has been achieved. Based on
our work a number of alternative proposals for measuring ``$g$" on both charged
and neutral antimatter have been made. We summarize the present status of our
experiment and also discuss the steps that would be necessary to produce
antihydrogen in an environment suitable for gravity measurements.


title: The instanton liquid in QCD at zero and finite temperature

abstract:
  In this paper we study the statistical mechanics of the instanton liquid in
QCD. After introducing the partition function as well as the gauge field and
quark induced interactions between instantons we describe a method to calculate
the free energy of the instanton system. We use this method to determine the
equilibrium density and the equation of state from numerical simulations of the
instanton ensemble in QCD for various numbers of flavors. We find that there is
a critical number of flavors above which chiral symmetry is restored in the
groundstate. In the physical case of two light and one intermediate mass flavor
the system undergoes a chiral phase transition at $T\simeq 140$ MeV. We show
that the mechanism for this transition is a rearrangement of the instanton
liquid, going from a disordered, random, phase at low temperatures to a
strongly correlated, molecular, phase at high temperature. We also study the
behavior of mesonic susceptibilities near the phase transition.


title: The Phase Transition of the Two Higgs extension of the Standard Model

abstract:
  We present the analysis of the phase transition for the two Higgs electroweak
model. We have found that for a wide range of parameters the universe first
tunnels to a new intermediate phase. This feature not only is very important by
itself, but also provides the essential requirements for producing baryon
asymmetry with only small explicit CP-violating terms in the two Higgs tree
Lagrangian.


title: The $W_R$ production in $e\gamma$ collisions

abstract:
  We consider the production of a single right-handed gauge boson $W_R$ in the
high-energy $e^-\gamma$ collisions with polarized beams. If the associated
neutrino is light, the reaction will give the best discovery reach for $W_R$ in
the Next Linear Collider.


title: Constituent gluons from QCD

abstract:
  The notion of constituent gluon is introduced as a gluon propagating in the
vacuum background field. The Hamiltonian approach for a system containing such
gluon and a $q\bar{q}g$ pair is formulated, and the masses of lowest
$q\bar{q}g$ hybrids are estimated.


title: Off shell W pair production in e+ e- annihilation: The CC11 process

abstract:
  The various four-fermion production channels in $e^+ e^-$ annihilation are
discussed and the {\tt CC11} process $e^+ e^- \rightarrow {\bar f}_1^u f_1^d
f^u_2 {\bar f}_2^d$, {\mbox{$f$$\neq$$e$}}, is studied in detail. The cross
section $d^2\sigma/ds_1ds_2$, with $s_1,s_2$ being the invariant masses squared
of the two fermion pairs, may be expressed by six generic functions. All but
one may be found in the literature. The cross section, including initial state
radiation and the Coulomb correction, is discussed and compared with other
calculations from low energies up to $\sqrt{s}$ = 2 ~TeV.


title:
On the P-Wave Contributions to the Cross Sections of $t\bar{t}$ and
  $\t\bar{\t}$ Near Threshold

abstract:
  The approach used for the determination of S-wave amplitudes containing the
application of the nonrelativistic approximation in the case of P-waves leads
to unphysical divergencies. We show how to avoid the latter in calculations of
contributions to the cross section near threshold in agreement with field
theory. This enables us to give quantitatively reliable predictions for the
forward-backward asymmetry and for the axial contribution to the total cross
section for the top-antitop system. Also the cross section for the production
of stop-antistop near threshold is determined.


title: The Colour of Quarks

abstract:
  It is shown that colour can only be defined on gauge invariant states. Since
the ability to associate colour with constituent quarks is an integral part of
the constituent quark model, this means that, if we want to extract constituent
quarks from QCD, we need to dress Lagrangian quarks with gluons so that the
result is gauge invariant. We further prove that gauge fixings can be used to
construct such dressings. Gauge invariant dressed quark states are presented
and a direct approach to the interquark potential is discussed. Some further
aspects of dressing quarks are briefly discussed.


title: Constituent Quarks from QCD

abstract:
  Starting from the observation that colour charge is only well defined on
gauge invariant states, we construct perturbatively gauge invariant, dynamical
dressings for individual quarks. Explicit calculations show that an infra-red
finite mass-shell renormalisation of the gauge invariant, dressed propagator is
possible and, further, that operator product effects, which generate a running
mass, may be included in a gauge invariant way in the propagator. We explain
how these fields may be combined to form hadrons and show how the interquark
potential can now be directly calculated. The onset of confinement is
identified with an obstruction to building a non-perturbative dressing. We
propose several methods to extract the hadronic scale from the interquark
potential. Various extensions are discussed.


title:
First and Second Order Phase Transitions in Maxwell--Chern-Simons Theory
  Coupled to Fermions

abstract:
  In the Maxwell--Chern-Simons theory coupled to $N_f$ flavors of 4-component
fermions (or even number of 2-component fermions) we construct the
gauge-covariant effective potential written in terms of two order parameters
which are able to probe the breakdown of chiral symmetry and parity. In the
absence of the bare Chern-Simons term, we show that the chiral symmetry is
spontaneously broken for fermion flavors $N_f$ below a certain finite critical
number $N_f^c$, while the parity is not broken spontaneously. This chiral phase
transition is of the second order. In the presence of the bare Chern-Simons
term, on the other hand, the chiral phase transition associated with the
spontaneous breaking of chiral symmetry is shown to continue to exist, although
the parity is explicitly broken. However it is shown that the existence of the
bare Chern-Simons term changes the order of the chiral transition into the
first order, no matter how small the bare Chern-Simons coefficient may be. This
gauge-invariant result is consistent with that recently obtained by the
Schwinger-Dyson equation in the non-local gauge.


title: Importance of Dipole Penguin Operator in $B$ Decays

abstract:
  The importance of dipole penguin operator, $O_{11} = (g_s/8\pi^2)m_b \bar s
\sigma_{\mu\nu}RT^a b G^{\mu\nu}_a$, on B decays is demonstrated. It is shown
that branching ratios for the inclusive decay $b\to s s\bar s$, the
semi-inclusive decay $b\to s\phi$, and the exclusive decay $B\to \pi K$ are
enhanced by 20% to 30%. A useful consequence of this calculation is the
inclusive $b\to ss\bar s$ spectrum which will be essential in isolating pure
penguin process.


title: Nonperturbative effects on nucleation

abstract:
  A nonperturbative correction to the thermal nucleation rate of critical
bubbles in a first order phase transition is estimated. The correction
originates from large-amplitude fluctuations which may be present before the
transition occurs. Using a simple model of a scalar field in a double-well
potential, we present a method to obtain a corrected potential which
incorporates the free-energy density available from large-amplitude
fluctuations, which is not included in the usual perturbative calculation. For
weaker phase transitions, the nucleation rate can be much larger than the rate
calculated via perturbation theory. As an application of our method, we show
how nonperturbative corrections can both qualitatively and quantitatively
explain anomalously high nucleation rates observed in 2-d numerical
simulations.


title: Operator expansion for high-energy scattering

abstract:
  I demonstrate that the leading logarithms for high-energy scattering can be
obtained as a result of evolution of the nonlocal operators - straight-line
ordered gauge factors - with respect to the slope of the straight line.


title: Unitarity and the Time Evolution of Quantum Mechanical Systems

abstract:
  The basic requirement that, in quantum theory, the time-evolution of any
state is determined by the action of a unitary operator, is shown to be the
underlying cause for certain ``exact'' results which have recently been
reported about the time-dependence of transition rates in quantum theory.
Departures from exponential decay, including the ``Quantum Zeno Effect'', as
well as a theorem by Khalfin about the ratio of reciprocal transition-rates,
are shown to follow directly from such considerations. At sufficiently short
times, unitarity requires that reciprocity must hold, independent of whether
$T$-invariance is valid. If $T$-invariance does not hold, unitarity restricts
the form of possible time-dependence of reciprocity ratios.


title: Top quark effects on the scalar sector of the minimal Standard Model

abstract:
  We study effects of the heavy top quark ($m_t \approx 180 GeV$) on the scalar
sector of the minimal Standard Model. We construct the effective potential for
the scalar doublet, by first taking into account the leading contributions of
the top quark loops. Minimizing this potential gives us a condition analogous
to the leading-Nc gap equation of the standard ${\bar t}t$-condensation model
(Top-mode standard model). This essentially nonperturbative condition leads to
a low ultraviolet cutoff $\L = O(1 TeV)$ in the case when the bare mass $\mu$
of the scalar doublet in the tree level potential satisfies $\mu^2 = -M^2_0
\leq 0$ and the scalar doublet there is selfinteracting ($\lambda > 0$). We
demand that the scalar selfinteraction behave perturbatively -- in the sense
that its 1-loop contributions influence the effective poten- tial distinctly
less than those of the Yukawa coupling of the heavy top quark. When we
subsequently include the 1-loop contributions of the scalar and the gauge
bosonic sectors in a perturbative manner, the results change numerically, but
the cutoff $\L$ remains $O(1 TeV)$. The resulting Higgs mass $M_H$ is then in
the range 150-250 GeV. Furthermore, the results of the paper survive even in
the case when the square of the bare mass $\mu^2$ is positive, as long as
$\mu^2 \leq O(\lambda v^2)$, where $\lambda/4!$ is the usual bare coupling
parameter of the quartic selfinteraction of the scalars and $v$ is the vacuum
expectation value ($v=246.2 \GeV$, $M^2_H \approx \lambda v^2/3$).


title: Textures for Neutrino Mass Matrices

abstract:
  We give a classification of heavy Majorana neutrino mass matrices with up to
three texture zeroes, assuming the Dirac masses of the neutrinos to be of the
same form as the ones of the up-quarks in the five texture zero solutions for
the quark matrices. This is the case for many unified and partially unified
models. We find that it is possible to have solutions which account for the
solar and atmospheric neutrino problems as well as the COBE observations
simultaneously, and we motivate the existence of such solutions from
symmetries.


title: Bound States in the Hot Electroweak Phase

abstract:
  The high temperature phase of the electroweak standard theory is described by
a strongly coupled SU(2)-Higgs-model in three dimensions. As in the
Abbott-Farhi-model Higgs and W-boson are low lying bound states. Using a method
by Simonov based on the Feynman-Schwinger representation of correlators we
calculate the masses of these states. Our results are compared with lattice
masses.


title: Studies of Unitarity at Small~$x$ Using the Dipole Formulation

abstract:
  Mueller's dipole formulation of onium-onium scattering is used to study
unitarity corrections to the BFKL power growth at high energies. After a short
discussion of the spatial distribution of colour dipoles in a heavy quarkonium
and the associated fluctuations, results are presented showing that the one and
two-pomeron contributions to the total cross section are the same at a rapidity
$Y \simeq 14$. Above this rapidity the large fluctuations in the onium wave
function cause the multiple pomeron series to diverge. Resumming the series
allows one to show that unitarity corrections set in gradually for the total
cross section, which is dominated by rare, large, configurations of the onia.
The elastic cross section comes mostly from much smaller impact parameters and
has significant unitarity corrections starting at a rapidity $Y\simeq 8$.


title: A ${\bf Z}_2$ Origin for B+L Violation in the Hot Electroweak Theory

abstract:
  The space of static finite-energy configurations of the electroweak theory
admits a ${\bf Z}_{2}$ topological structure. Odd-parity configurations with
odd pure-gauge behavior at spatial infinity (S sphaleron, W-Z strings,
multisphalerons) mediate rapid $B+L$ violation in the Early Universe.
Configurations with even pure-gauge behavior (S$^{*}$ sphalerons, W-Z strings,
multisphalerons) are trivial and topologically equivalent to the vacuum.


title: Prompt Upsilon and Psi Production at LEP

abstract:
  Color-octet contributions to quarkonia production at LEP are studied herein.
The short distance formation of heavy quark-antiquark pairs in color-octet
configurations via gluon fragmentation processes is significantly enhanced
relative to the creation of color-singlet pairs via heavy quark fragmentation.
But the subsequent long distance hadronization of these colored pairs into
physical quarkonium bound states is suppressed compared to the nonperturbative
evolution of their colorless counterparts. We find that the overall LEP rates
for gluon fragmentation into prompt Upsilon and Psi vector bosons exceed those
from heavy quark fragmentation. Inclusion of the dominant color-octet
quarkonium production channel eliminates sizable discrepancies between previous
predictions and recent measurements of prompt $Z \to \Jpsi+X$, $Z \to \psi'+X$
and $Z \to \Upsilon+X$ branching fractions.


title:
Perturbative QCD estimation of the $B \to K^{*} + \gamma$ branching
  ratio

abstract:
  Working in a perturbative QCD model approach, we obtain the essential form
factor of the radiative transition $B \rightarrow V^{*} \gamma$ and estimate
the branching ratio $BR(B \rightarrow K^{*} \gamma)$. The results are
determined by a parameter expressing the momentum distribution in the $B$ -
meson wave function. Our estimations are compared to other theoretical
predictions as well as to experimental data.


title: Color Transparency or the Standard Inelastic Shadowing?

abstract:
  The standard first-order inelastic correction (IC) well known in the pre-QCD
era, causes a rising $Q^2$-dependence of nuclear transparency in the
quasielastic electron scattering, $A(e,e'p)A'$, at moderate $Q^2$, similar to
what is supposed to be the onset of color transparency (CT). Although IC is a
part of the whole pattern of CT, it contains no explicit QCD dynamics.
Evaluation of this correction is based on experimental data on diffraction
dissociation and is independent of whether CP phenomenon exists or not. The
growth of nuclear transparency is numerically comparable with the expected
signal of CT up to about $Q^2\approx 20\ GeV^2$. Analogous effect in
$A(p,2p)A'$ reaction is estimated as well.


title:
Lattice-Constrained Unitarity Bounds for $\bar B^0 \to \pi^+ l^- \bar
  \nu_l$ Decays

abstract:
  Lattice results, kinematical constraints and QCD dispersion relations are
combined for the first time to derive model-independent bounds for QCD form
factors and corresponding rates. To take into account the error bars on the
lattice results we develop a general formalism which ascribes well-defined
statistical properties to these bounds. We concentrate on $\bar B^0 \to \pi^+
l^- \bar\nu_l$ decays because of the relative simplicity of the analytical
behavior of the relevant polarization functions and because of their immediate
phenomenological relevance. To determine the range of applicability of the
dispersive matching required to obtain the bounds, we have evaluated the
leading perturbative and non-perturbative QCD corrections to the relevant
polarization functions. Despite the lattice results' large error bars and
limited kinematical range, the bounds we obtain appear to favor certain
parametrizations for the form factors over others. The bounds also enable the
determination of $|V_{ub}|$ from the total experimental rate with a theoretical
error ranging from 27% to 37%, depending on the assumptions made. The
techniques developed here are, in fact, quite general and are not limited to
use with lattice results nor to semileptonic $\bar B^0 \to \pi^+ l^- \bar\nu_l$
decays.


title: Damping rate of neutrinos in the singlet Majoron model

abstract:
  The damping rate and free path of neutrinos in the singlet Majoron model have
been calculated including both finite temperature and symmetry breaking
effects. The behaviour of right- and left-handed fermions are found inherently
different. While the damping rates of the left-handed leptons are essentially
model independent, e.g. directly applicable to the Standard Model, for the
right-handed particles the rates are crucially sensitive to parameters of the
scalar sector. In general, the damping rates are fairly large. The possibility
of the right-handed neutrinos to penetrate deep into the broken phase in the
electroweak phase transition still remains, however, for some parts of
parameter space.


title:
Contrasting Real-time Dynamics with Screening Phenomena at Finite
  Temperature

abstract:
  We discuss the interpretation of Euclidean correlation functions at finite
temperature ($T$) and their relationship with the corresponding real-time
Green's functions. The soluble 2+1 dimensional Gross-Neveu model in the
large-$N$ limit is used throughout as a working example. First, the real-time
bound state, identified as an elementary excitation at finite $T$, is solved.
The bound state mass, the dispersion relation at low momenta, the coupling
constant and decay constant are calculated. To characterize the structure of
the bound state the on-shell form factor is carefully introduced and
calculated. Then we examine the corresponding screening state and contrast the
screening mass, coupling constant, decay constant and the screening
Bethe-Salpeter amplitude with the real-time quantities. We find that, although
they can be used as qualitative indicators in the low-$T$ regime, the screening
states at finite $T$ in general do not reflect the properties of the
corresponding real-time bound states. Besides, other relevant issues, such as
the subtlety of the real-time manifestation of conservation laws due to some
internal symmetries at $T\ne 0$, the temperature dependence of the pseudoscalar
spectral function and its sum rule, and the high-$T$ limit of the screening
state and its implications to the dimensional reduction, are also discussed in
detail.


title: $c\to u \gamma$ in Cabibbo suppressed D meson radiative weak decays

abstract:
  We investigate Cabibbo suppressed $D^{0}$, $D^{+}$ and $D^{+}_{s}$ radiative
weak decays in order to find the best mode to test $c\to u \gamma$ decay.
Combining heavy quark effective theory and the chiral Lagrangian approach we
determine the decay widths. We calculate $\Gamma(D^{0}\to
\rho^{0}/\omega\gamma)/ \Gamma(D^{0}\to {\bar K}^{*0} \gamma)$ previously
proposed to search for possible New Physics. However, we notice that there are
large, unknown, corrections within the Standard Model. We propose a better
alternative, the ratio $\Gamma(D_{s}^{+}\to K^{*+} \gamma)/ \Gamma(D_{s}^{+}\to
\rho^{+} \gamma)$, and show that it is less sensitive to the Standard Model.


title: Scaling Variable for Nuclear Shadowing in Deep-Inelastic Scattering

abstract:
  A new scaling variable is introduced in terms of which nuclear shadowing in
deep-inelastic scattering is universal, i.e. independent of $A$, $Q^2$ and $x$.
This variable can be interpreted as a measure of the number of gluons probed by
the hadronic fluctuations of a virtual photon during their lifetime. The
shadowing correction grows at small $x$ substantially less steeply than is
suggested by the eikonal approximation. This results from the fact that
shadowing is dominated by soft rather than hard interactions.


title:
Analytic structure of meson propagators in the proper-time regularized
  Nambu--Jona-Lasinio model

abstract:
  We analyze the analytic structure of meson propagators in the
Nambu--Jona-Lasinio model with a proper-time regulator. We show that the
regulator produces unphysical complex singularities. As a result the naive use
of the Wick rotation is no longer allowed. Formulas involving integration over
mesonic momenta, such as meson-loop contributions or dispersion relations for
meson Green's functions, cannot be written in usual forms.


title:
Production and decay of single heavy spin-3/2 leptons in high energy
  electron-positron collisions

abstract:
  We discuss the possibility of detecting heavy spin-3/2 leptons at LEP2 and
NLC energies. The angular distributions of primary ordinary leptons are shown
to be a good measure to discriminate between a heavy spin-3/2 lepton and a
similar nonstandard spin-1/2 signal.


title: A Supersymmetric SO(10) Model with Inflation and Cosmic Strings

abstract:
  We have built a supersymmetric SO(10) model consistent with cosmological
observations. The model gives rise to a false vacuum hybrid inflationary
scenario which solves the monopole problem. We argue that this type of
inflationary scenario is generic in supersymmetric SO(10) model, and arises
naturally from the theory. Neither any external field nor any external symmetry
has to be added. It can just be a consequence of the theory. In our specific
model, at the end of inflation, cosmic strings form. The properties of the
strings are presented. The cosmic background radiation anisotropies induced by
the inflationary perturbations and the cosmic strings are estimated. The model
produces a stable lightest superparticle and a very light left-handed neutrino
which may serve as the cold and hot dark matter. The properties of a mixed
cosmic string-inflationary large scale structure formation scenario are
discussed.


title: Magnetic Moments of the Octet Baryons in the Colour-Dielectric Model

abstract:
  Baryon magnetic moments are calculated in the colour-dielectric model with
pion and kaon loops. The only free parameter of the model is determined from
the nucleon isoscalar radius, and all SU(3) symmetry breaking, including that
in the quark sector, is determined by mesonic masses and decay constants. Good
agreement with experiment is obtained for the ratios of the magnetic moments,
but the inclusion of kaons does not improve the results. The results obtained
in this approach are significantly better than any that have been obtained in
hedgehog-based models.


title:
Pre-Equilibrium Stage and Phase Transition of Quark Matter Probed by
  Photon Interferometry

abstract:
  We study single- and double-inclusive spectra of thermal photons, produced in
heavy-ion collisions at $\sqrt{s}=200$ AGeV within a realistic space-time
framework which combines the Parton-Cascade-Model and 3-dimensional
hydrodynamics (HYLANDER). This allows also for the first time to take into
account pre-equilibrium effects for photon production. A rapid decrease in the
width of the correlation function as the photon transverse momentum drops below
$\sim 1.5$ GeV is a signature of the deconfinement phase transition.


title: Masses of spin-1 mesons and dynamical chiral symmetry breaking

abstract:
  In terms of an effective chiral theory of mesons it is shown quantitatively
that in the limit of $m_{q}=0$, the masses of $\rho$, $\omega$, $K^{*}(892)$,
$m_{\phi}$, $a_{1}$, $f_{1}(1286)$, $K_{1}(1400)$, and $f_{1}(1510)$ mesons
originate from dynamical chiral symmetry breaking.


title:
Universal scaling of the valence quark mass dependence of the chiral
  condensate

abstract:
  Recently, the Columbia group obtained the valence quark mass dependence of
the chiral condensate for lattice QCD simulations with dynamical fermions for a
series of couplings close to the critical temperature. In this letter we show
that the data for temperatures below $T_c$ and sufficiently small valence quark
masses can be rescaled to fall on a universal curve. Using chiral random matrix
theory we obtain an exact analytical expression for the shape of this curve. We
also discuss the universal scaling behavior of the mass dependence of the mass
derivatives of the chiral condensate (scalar susceptibilities).


title:
Quantum Interference: From Kaons to Neutrinos (with Quantum Beats in
  between)

abstract:
  Using the vehicle of resolving an apparent paradox, a discussion of quantum
interference is presented. The understanding of a number of different physical
phenomena can be unified, in this context. These range from the neutral kaon
system to massive neutrinos, not to mention quantum beats, Rydberg wave
packets, and neutron gravity.


title: The Spin-Flavor Dependence of Nuclear Forces from Large-N QCD

abstract:
  We show that nuclear interactions are SU(4) symmetric at leading order in
chiral perturbation theory in the large-N limit of QCD. The nucleons and delta
resonances form a 20-dimensional representation of SU(4) and we show how
Wigner's supermultiplet symmetry SU(4)_{sm}, under which the nucleons transform
as a 4-dimensional representation, follows as an accidental low energy
symmetry. Exploiting SU(4) symmetry allows one to express the 18 independent
leading nucleon, delta interaction operators invariant under spin and isospin
symmetries in terms of only two couplings. The three flavor analogue allows one
to express the 28 leading octet, decuplet interactions also in terms of only
two couplings, which has implications for hypernuclei and strangeness in
``neutron'' stars.


title: Analysis of $K_L \to \gamma \nu \bar{\nu}$

abstract:
  The decay $K_L \to \gamma \nu \bar{\nu}$ is analyzed within the standard
model. Short-distance contributions are found to dominate, yielding a branching
ratio of $\sim 0.7 \times 10^{-11}$. We examine the possibility that
non-standard model effects might be observed at higher rates. As an example, we
calculate the branching ratio for the process mediated by neutral horizontal
gauge bosons. Notwithstanding some model uncertainties, experimental limits for
lepton number violation constrains these contributions to $\lesssim 2\times
10^{-11}$.


title: Hadronic photon-photon interactions at high energies

abstract:
  Photon-photon collisions are investigated in the framework of the
two-component Dual Parton Model. The model is shown to agree well to hadron
production data from hadron-hadron and photon-hadron collisions. The
multiparticle production in hadron-hadron, photon-hadron and photon-photon
collisions as predicted by the model is compared. Strong differences are only
found as function of the transverse momentum variable. The hadron production in
photon-photon collisions at present and future electron-positron colliders is
studied using photon spectra according to the equivalent photon approximation,
according to beamstrahlung and according to backscattered laser radiation.


title:
Final State Interactions and Khuri-Treiman Equations in $\eta\to 3\pi$
  decays

abstract:
  Using extended Khuri-Treiman equations, we evaluate the final state
interactions due to two-pion rescatterings to the decays $\eta\to \pi^0 \pi^+
\pi^-$ and $\eta\to \pi^0 \pi^0 \pi^0$. As subtraction to the dispersion
relation we take the one-loop chiral perturbation theory result of Gasser and
Leutwyler. The calculated corrections are moderate and amount to about $14\%$
in the amplitude at the center of the decay region. A careful analysis of the
errors inherent to our approach is given. As a consequence, the experimental
rate of the decay can only be reproduced if the double quark mass ratio
$Q^{-2}\equiv\frac{m_{d}-m_{u}} {m_{s}-{\hat m}}
\cdot\frac{m_{d}+m_{u}}{m_{s}+{\hat m}}$ is increased from the usual value of
$1/(24.1)^2$ to $1/(22.4 \pm 0.9)^2$. We have also calculated the ratio of the
rates of the two decays and various Dalitz Plot parameters. In particular, the
linear slope $a$ in the charged decay is different from the one-loop value and
agrees better with experiment.


title: $\psi'$ Polarization as a test of colour octet quarkonium production

abstract:
  We calculate the $\alpha_s$ corrections to the transverse polarization
fraction of $\psi^\prime$'s produced at the Tevatron. If the
`$\psi^\prime$-anomaly' is explained by gluon fragmentation into a colour octet
Fock component of the $\psi^\prime$, the $\psi^\prime$'s should be $100\%$
transversely polarized at leading order in $\alpha_s$, up to spin symmetry
breaking long-distance corrections. We find that the short-distance correction
to the transverse polarization fraction is a few percent, so that a
polarization measurement would provide a reliable test of the colour octet
mechanism.


title: Recent status of leptohadron hypothesis

abstract:
  TGD predicts the existence of color octet excitations of ordinary leptons
forming 'leptohadrons' as their color singlet bound states. There is some
evidence on the existence of leptohadrons: the production of anomalous $e^+e^-$
pairs in heavy ion collisions, Karmen anomaly, the anomalously high decay rate
of ortopositronium (Op) and anomalous production of low energy $e^+e^-$ pairs
in hadronic collisions. PCAC makes it possible to predict the couplings of
leptopion to leptons. The new contribution to Op decay rate is of correct order
of magnitude and the anomaly allows to determine the precise value of the
parameter $f_{\pi_L}$. Sigma model realization of PCAC makes it possible to
construct a model for the production of leptohadrons in the electromagnetic
fields of the colliding nuclei. $\pi_L$ develops vacuum expectation value
proportional to the 'instanton density' $E\cdot B$ and it is possible to relate
leptohadron production rates to the Fourier transform of $E\cdot B$. Anomalous
$e^+e^-$ pairs must originate from $\sigma_L \pi_L$ pairs via
$\sigma_L\rightarrow e^+e^-$ decay. The peculiar production characteristics of
leptomesons are reproduced, the order of magnitude for the production cross
section is correct and various decay rates are within experimental bounds. A
resonance in photon photon scattering at cm energy equal to leptopion mass is
predicted and leptobaryon pair production in heavy ion collisions is in
principle possible. Leptopion contribution to the $\nu-e$ and $\bar{\nu}-e$
scattering should dominate at low energies.


title: Novel Features of Multiplicity Distributions in QCD and Experiment

abstract:
  The solution of QCD equations for generating functions of multiplicity
distributions reveals new peculiar features of cumulant moments oscillating as
functions of their rank. This prediction is supported by experimental data on
$e^{+}e^{-}, hh, AA$ collisions. Evolution of the moments at smaller phase
space bins leads to intermittency and fractality. The experimentally defined
truncated generating functions possess zeros in the complex plane of the
auxiliary variable recalling Lee-Yang zeros in statistical mechanics.


title:
Improved Evaluation of the Hadronic Vacuum Polarization Contributions to
  Muon $g-2$ and $\bar\alpha_{\rm QED}(M_Z)$ Using High Order QCD Calculations

abstract:
  We use recently evaluated radiative and nonperturbative corrections to
production of heavy quarks by a vector current to give very precise theoretical
calculations of the high energy ($t^{1/2}\geq \sqrt{2}$ GeV) imaginary part of
the photon vacuum polarization function, ${\rm Im}\Pi(t)$. This allows us to
improve the corresponding contributions to the muon (or any other lepton) $g-2$
anomaly and to the running QED constant on the $Z$, $\bar\alpha_{\rm
QED}(M_Z)$. This decreases the error in the evaluations by a factor between two
and six for the high energy contribution, and by some 50\% for the overall
result. We find for the hadronic contributions
$a_h=6993.4\pm110.0\times10^{-11}$ and
$\Delta\alpha_h=272.59\pm4.09\times10^{-4}\,.$


title:
Flavour changing neutral currents and CP violating processes in
  generalized supersymmetric theories

abstract:
  We consider supersymmetric extensions of the standard model with general
non-universal soft breaking terms. We analyse in a model-independent way the
constraints on these terms at the electroweak energy scale coming from gluino
mediated flavour (F) changing neutral current and CP-violating processes. We
have computed the complete $\Delta F=1$ and $\Delta F=2$ effective hamiltonian
for gluino mediated processes, including for the first time the effect of box
diagrams in the evaluation of $\epsilon^{\prime}/\epsilon$. We present
numerical results for the constraints on these non-universal soft breaking
terms for different values of the parameters, extending the analysis also to
the leptonic sector. A comparison with previous results in the literature is
given.


title:
(2+1)-Dimensional QED with Dynamically Massive Fermions in the Vacuum
  Polarization

abstract:
  We study chiral symmetry breaking in $\rm QED_3$ with $N_f$ flavors of
four-component fermions. A closed system of Schwinger-Dyson equations for
fermion and photon propagators and the full fermion-photon vertex is proposed,
which is consistent with the Ward-Takahashi identity. A simplified version of
that set of equations is reduced (in nonlocal gauge) to the equation for a
dynamical fermion mass function, where the one-loop vacuum polarization with
dynamically massive fermions has been taken into account. The linearized
equation for the fermion mass function is analyzed in real space. The
analytical solution is compared with the results of numerical calculations of
the nonlinear integral equation in momentum space.


title: Charmonium Theory

abstract:
  Recent theoretical progress in calculations of the spectrum and decays of
charmonium is reviewed. Traditionally, our understanding of charmonium was
based on potential models. This is now being replaced by first principles.


title:
Scalar-Scalar Ladder Model in the Unequal-Mass Case. II ---Numerical
  Studies of the BS Amplitudes ---

abstract:
  The Bethe-Salpeter amplitudes of the bound states formed by two scalar
particles with unequal masses are analyzed in the massive scalar particle
exchange ladder model. The norms of the amplitudes are calculated numerically,
and it is confirmed that the norm vanishes for the bound state corresponding to
the complex eigenvalue of the coupling constant. The behaviour of the
Bethe-Salpeter amplitudes in the momentum space is also investigated.


title: Derivative Expansion for the One-Loop Effective Lagrangian in QED

abstract:
  The derivative expansion of the one-loop effective Lagrangian in QED$_4$ is
considered. The first term in such an expansion is the famous Schwinger result
for a constant electromagnetic field. In this paper we give an explicit
expression for the next term containing two derivatives of the field strength
$F_{\mu\nu}$. The results are presented for both fermion and scalar
electrodynamics. Some possible applications of an inhomogeneous external field
are pointed out.


title: Dynamical Electroweak Symmetry Breaking and the Top Quark

abstract:
  In this talk I discuss theories of dynamical electroweak symmetry breaking,
with emphasis on the implications of a heavy top-quark on the weak-interaction
$\rho$ parameter.


title: Status of effective potential calculations

abstract:
  We review various effective potential methods which have been useful to
compute the Higgs mass spectrum and couplings of the minimal supersymmetric
standard model. We compare results where all-loop next-to-leading-log
corrections are resummed by the renormalization group, with those where just
the leading-log corrections are kept. Pole masses are obtained from running
masses by addition of convenient self-energy diagrams. Approximate analytical
expressions are worked out, providing an excellent approximation to the
numerical results which include all next-to-leading-log terms. An appropriate
treatment of squark decoupling allows to consider large values of the stop
and/or sbottom mixing parameters and thus fix a reliable upper bound on the
mass of the lightest CP-even Higgs boson mass.


title: CP Violation and Quantum Mechanics in the B System

abstract:
  We discuss the testing of the Standard Model of CP violation, and the search
for CP-violating effects from beyond the Standard Model, in $B$ decays. We then
focus on the quantum mechanics of the experiments on CP violation to be
performed at $B$ factories. These experiments will involve very pretty
Einstein-Podolsky-Rosen correlations. We show that the physics of these
experiments can be understood without invoking the ``collapse of the wave
function," and without the mysteries that sometimes accompany discussions of
EPR effects.
  (To appear in the Proceedings of the Moriond Workshop on Electroweak
Interactions and Unified Theories, Les Arcs, France, March 1995)


title: Solar Neutrinos: Expecting 1996

abstract:
  These are remarks (mainly on the solar neutrinos) written in anticipation of
1996 - the year which can be crucial for the neutrino physics. Recent results
on solar neutrinos are discussed. The topics include: (solar) model independent
approach to the solar neutrino problem, status of different solutions of the
problem, standard and non-standard scenarios of the lepton mixing, light
singlet fermions and the neutrino phenomenology.


title: Aspects of Charmonium

abstract:
  Here we discuss three separate topics in charmonium physics. (1) The Omicron
\OMC as $1^{--}$ trigluonia, and the charmonium puzzle; the $\eta_c' (3600)$
search. (2) The decay $\psi(^1P_1) \to \pi^o + J/\psi$ and isospin violating
charmonium decays. (3) How to search for $\chi_c' = \chi_c(2P)$ charmonium
states.


title: Lepton Mass Hierarchy and Neutrino Oscillations

abstract:
  Starting from the symmetry of lepton flavor democracy, we propose and discuss
a simple pattern for the mass generation and flavor mixing of the charged
leptons and neutrinos. The three neutrino masses are nearly degenerate, and the
flavor mixing angles can be calculated. The observed deficit of solar and
atmospheric neutrinos can be interpreted as a consequence of the near
degeneracy and large oscillations of $\nu_e$, $\nu_{\mu}$ and $\nu_{\tau}$ in
the vacuum. Our {\it Ansatz} can also accommodate the cosmological requirement
for hot dark matter and the current data on neutrinoless $\beta\beta$-decay.


title:
Constraints on Composite-Models Effective Lagrangians from Neutrinoless
  Double Beta Decay

abstract:
  We give a brief review of the existing bounds on effective couplings for
excited states ($e^*, \nu^*, u^*, d^* $) of the ordinary quarks and leptons
arising from a composite model scenario. We then explore the phenomenological
implications of the hypothesis that the excited neutrino $\nu^*$ might be of
Majorana type. Recent bounds on the half-life of the $\Delta L =2 $
neutrinoless double beta decay ($0\nu\beta\beta $) are used to constraint the
compositeness effective couplings. We show that the bounds so obtained are
roughly of the same order of magnitude as those available from high energy
experiments.


title:
Psi' and J/Psi Suppression in High-Energy Nucleon-Nucleus and
  Nucleus-Nucleus Collisions

abstract:
  The observed features of $\psi'$ to $J/\psi$ suppression in $pA$ and
nucleus-nucleus collisions can be explained in terms of a two-component
absorption model. For the hard component of the absorption due to the
interaction of the produced $c\bar c$ systems with baryons at high relative
energies, the absorption cross sections are insensitive to the radii of the
$c\bar c$ systems, as described by the Additive Quark Model. For the soft
component due to the low energy $c \bar c$ interactions with soft particles
produced by other baryon-baryon collisions, the absorption cross sections are
greater for $\psi'$ than for $J/\psi$, because the breakup threshold for
$\psi'$ is much smaller than for $\psi$.


title: Testing Extended Technicolor With $R_b$

abstract:
  We review the connection between $m_t$ and the $Zb\bar b$ vertex in ETC
models and demonstrate the power of the resulting experimental constraint on
models with weak-singlet ETC bosons. Some efforts to bring ETC models into
agreement with experimental data on the $Zb\bar b$ vertex are mentioned, and
the most promising one (non-commuting ETC) is discussed in detail.


title: The Strangeness Radius and Magnetic Moment of the Nucleon Revisited

abstract:
  We update Jaffe's estimate of the strange isoscalar radius and magnetic
moment of the nucleon. We make use of a recent dispersion--theoretical fit to
the nucleon electromagnetic form factors and an improved description of
symmetry breaking in the vector nonet. We find $\mu_s = -0.24 \pm 0.03$~n.m.
and $r_s^2 = 0.21 \pm 0.03$~fm$^2$. The strange formfactor $F_2^s (t)$ follows
a dipole with a cut--off mass of 1.46~GeV, $F_2^s (t)= \mu_s (1-t/2.14 \, {\rm
GeV}^2 )^{-2}$. These numbers should be considered as upper limits on the
strange vector current matrix--elements in the nucleon.


title: Supergravity and the $b\to s,\gamma$ decay

abstract:
  We evaluate the branching ratio BR($b\rightarrow s,\gamma$) in the minimal
supersymmetric standard model (MSSM), determining the corresponding
phenomenological restrictions on two attractive supergravity scenarios, namely
minimal supergravity and a class of models with a natural solution to the $\mu$
problem. We have included in the calculation some one--loop refinements that
have a substantial impact on the results. It is stressed the fact that an
eventual improvement of the experimental bounds of order $10^{-4}$ would
strengthen the restrictions on the MSSM dramatically. This would be enough to
discard these supergravity scenarios with $\mu<0$ if no discrepancy is found
with the standard model prediction, while for $\mu>0$ there will remain
low-energy windows.


title:
Bounds on the Higgs mass in the Standard Model and the Minimal
  Supersymmetric Standard Model

abstract:
  Depending on the Higgs-boson and top-quark masses, $M_H$ and $M_t$, the
effective potential of the {\bf Standard Model} can develop a non-standard
minimum for values of the field much larger than the weak scale. In those cases
the standard minimum becomes metastable and the possibility of decay to the
non-standard one arises. Comparison of the decay rate to the non-standard
minimum at finite (and zero) temperature with the corresponding expansion rate
of the Universe allows to identify the region, in the ($M_H$, $M_t$) plane,
where the Higgs field is sitting at the standard electroweak minimum. In the
{\bf Minimal Supersymmetric Standard Model}, approximate analytical expressions
for the Higgs mass spectrum and couplings are worked out, providing an
excellent approximation to the numerical results which include all
next-to-leading-log corrections. An appropriate treatment of squark decoupling
allows to consider large values of the stop and/or sbottom mixing parameters
and thus fix a reliable upper bound on the mass of the lightest CP-even Higgs
boson mass. The discovery of the Higgs boson at LEP~2 might put an upper bound
(below the Planck scale) on the scale of new physics $\Lambda$ and eventually
disentangle between the Standard Model and the Minimal Supersymmetric Standard
Model.


title: Radiative Decays of Hyperons in the Skyrme Model: E2/M1 Transitions

abstract:
  We study the radiative decays of $J^\pi=\frac{3}{2}^+$ baryons in the
framework of the SU(3) collective approach to the Skyrme model. We present the
predictions for the decay widths and the corresponding $E2/M1$ ratios. We find
that all considered ratios are negative and of the order of a few percent only.
We discuss the effects of flavor symmetry breaking and compare our results to
those obtained in related models.


title:
Unification Yang-Mills Groups and Representations with CP as a Gauge
  Symmetry

abstract:
  We investigate more generally the possible unification Yang-Mills groups
$G_{YM}$ and representations with CP as a gauge symmetry. Besides the possible
Yang-Mills groups $E_8$, $E_7$, $SO(2n+1)$, $SO(4n)$, $SP(2n)$, $G_2$ or $F_4$
(or a product of them) which only allow self-contragredient representations, we
present other unification groups $G_{YM}$ and representations which may allow
CP as a gauge symmetry. These include especially $SU(N)$ containing Weyl
fermions and their CP-conjugates from low-energy spectra in a basic irreducible
representation (IR). Such an example is the 496-dimensional basic IR (on
antisymmetric tensors of rank two) of $SU(32)$ containing $SO(32)$ as a
subgroup in the adjoint IR, or $SU(248)$ in a fundamental IR containing $E_8$
as a subgroup in the adjoint IR. Our consideration also leads to the
construction of a physical operator (CP) intrincially as an inner automorphism
of order higher than two for the unification group. We have also generalized
the possible groups as unification $G_{YM}$ to include non-semisimple Lie
groups with CP arising as a gauge symmetry. In this case with $U(1)$ ideals in
the $G_{YM}$, we found that the $U_Y(1)$ for weak hypercharge in the standard
model or a $U(1)$ gauge symmetry at low energies in general is traceless.
Possible relevance to superstring theory is also briefly discussed. We expect
that our results may open new alternatives for unified model building,
especially with deeper or more generalized understanding of anomaly-free
theories.


title: Baryons as Three Flavor Solitons

abstract:
  The description of baryons as soliton solutions of effective meson theories
for three flavor (up, down, strange) degrees of freedom is reviewed and the
phenomenological implications are illuminated. In the collective approach the
soliton configuration is equipped with baryon quantum numbers by canonical
quantization of the coordinates describing the flavor orientation. The baryon
spectrum resulting from exact diagonalization of the collective Hamiltonian is
discussed. The prediction of static properties such as the baryon magnetic
moments and the Cabibbo matrix elements for semi--leptonic hyperon decays are
explored with regard to the influence of flavor symmetry breaking. In
particular, the role of strange degrees of freedom in the nucleon is
investigated for both the vector and axial--vector current matrix elements. The
latter are discussed extensively within in the context of the {\it proton spin
puzzle}. The influence of flavor symmetry breaking on the shape of the soliton
is examined and observed to cause significant deviations from flavor covariant
predictions on the baryon magnetic moments. Short range effects are
incorporated by a chiral invariant inclusion of vector meson fields. These
extensions are necessary to properly describe the singlet axial--vector current
and the neutron proton mass difference. The effects of the vector meson
excitations on baryon properties are also considered. The bound state
description of hyperons and its generalization to baryons containing a heavy
quark are illustrated. In the case of the Skyrme model a comparison is
performed between the collective quantization scheme and bound state approach.
Finally, the Nambu--Jona--Lasinio model is employed to demonstrate that
hyperons can be described as solitons in a microscopic theory of the quark


title:
Constraint on the Reheating Temperature from the Decay of the Polonyi
  Field

abstract:
  We study the Polonyi problem in the framework of no-scale type supergravity
models. We show that the lightest superparticle (LSP) produced in the decay of
the Polonyi field may contribute too much to the present density of the
universe. By requiring that LSP should not overclose the universe, we obtain a
stringent constraint on the reheating temperature after the decay of the
Polonyi field. We calculate the LSP density with physical parameters obtained
by solving renormalization group equations in the minimal supersymmetric SU(5)
model and find that the reheating temperature should be greater than about
100MeV which corresponds to $O$(100)TeV of the Polonyi mass.


title: Slepton Production in Polarized $\gamma\gamma$ Scattering

abstract:
  We study slepton pair-production in polarized $\gamma\gamma$ scattering. It
turns out that the combined use of polarization and angular correlations
greatly enhances the resolving power of this reaction.


title: The mass of the eta' in self-dual QCD

abstract:
  The QCD gauge field is modeled as an ensemble of statistically independent
selfdual and antiselfdual regions. This model is motivated from instanton
physics. The scale anomaly then allows to relate the topological susceptibility
to the gluon condensate. With the help of Wittens formula for m_eta' and an
estimate of the suppression of the gluon condensate due to light quarks the
mass of the eta' can be related to f_pi and the physical gluon condensate. We
get the quite satisfactory value m_eta'=884+-116 MeV. Using the physical eta'
mass as an input it is in princple possible to get information about the
interaction between instantons and anti-instantons.


title: Proton Spin in the Instanton Background

abstract:
  The proton form factors are reduced to vacuum correlators of 4 quark fields
by assuming independent constituent quarks. The axial singlet quark and gluonic
form factors are calculated in the instanton liquid model. A discussion of
gauge(in)dependence is given.


title: Dyons in QCD: Confinement and Chiral Symmetry Breaking

abstract:
  Dyonic classical solutions of $SU(2)$ gluodynamics are discussed. Exact form
of dyonic solutions in different gauges is presented and the nontrivial problem
of composition of the dilute gas of dyons is settled. Classical interaction
between (anti)dyons is considered both analytically and numerically.
Confinement in the dyonic gas is discussed in connection with the topological
properties of individual dyon solution. Fermionic zero modes of dyonic are
displayed and the chiral symmetry breaking in the dyonic gas is demonstrated.


title: Hot Nonperturbative QCD


title: Pair Production in Small-Angle Bhabha Scattering

abstract:
  Radiative corrections due to the production of virtual as well as real soft
and hard pairs in small-angle Bhabha scattering are calculated analytically.
Both the collinear and the semi-collinear kinematical regions of hard pair
production are considered. The calculation, within the leading and
next-to-leading logarithmic approximation, provides an accuracy of O(0.1%).
Numerical results show that the effects of pair production have to be taken
into account for a luminosity determination accurate to O(0.1%) at LEP.


title:
Measurement of the proton and the deuteron structure functions F2p and
  F2d

abstract:
  The proton and deuteron structure functions F2p and F2d were measured in the
kinematic range 0.006<x<0.6 and 0.5<Q^2<75 GeV^2, by inclusive deep inelastic
muon scattering at 90, 120, 200 and 280 GeV. The measurements are in good
agreement with earlier high precision results. The present and earlier results
together have been parametrised to give descriptions of the proton and deuteron
structure functions F2 and their uncertainties over the range 0.006<x<0.9.


title: Duality of a Supersymmetric Standard Model

abstract:
  We examine a dual theory of a Supersymmetric Standard Model(SSM) in terms of
an $SU(3)_C$ gauge group. In this scenario, it is naturally understood that at
least one quark (the top quark) should be heavy, i.e., almost the same order as
the weak scale. Moreover, the supersymmetric Higgs mass parameter $\mu$ can
naturally be expected to be small. This model automatically induces nine pairs
of composite Higgs fields, which may be observed in the near future.


title: PQCD analysis of inclusive semileptonic decays of B mesons

abstract:
  We develop the perturbative QCD formalism for inclusive semileptonic $B$
meson decays, which includes Sudakov suppression from the resummation of large
radiative corrections near the high end of charged lepton energy. Transverse
degrees of freedom of partons are introduced to facilitate the factorization of
$B$ meson decays. Ambiguities appearing in the quark-level analysis are then
avoided. A universal distribution function, arising from the nonperturbative
Fermi motion of the $b$ quark, is constructed according to the heavy quark
effective field theory based operator product expansion, through which the mean
and the width of the distribution function are related to hadronic matrix
elements of local operators. Charged lepton spectra of the $B\to X_u\ell\nu$
decay are presented. We find 50\% suppression near the end point of the
spectrum. The overall suppression on the total decay rate is 8\% for the free
quark model, and is less than 7\% for the use of smooth distribution functions.
With our predictions, it is then possible to extract the
Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ from experimental data. We
also discuss possible implications of our analysis when confronted with the
rather small observed semileptonic branching ratio in $B$ meson decays.


title:
The Free Energy of High Temperature QED to Order $e^{5}$ From Effective
  Field Theory

abstract:
  Massless quantum electrodynamics is studied at high temperature and zero
chemical potential. We compute the Debye screening mass to order $e^{4}$ and
the free energy to order $e^{5}$} by an effective field theory approach,
recently developed by Braaten and Nieto. Our results are in agreement with
calculations done in resummed perturbation theory. This method makes it
possible to separate contributions to the free energy from different momentum
scales (order $T$ and $eT$) and provides an economical alternative to
computations in the full theory which involves the dressing of internal
propagators.


title: Soft scalar masses in supergravity with horizontal U(1)_X gauge symmetry

abstract:
  In supergravity with modular invariance and horizontal $U(1)_X$ gauge
symmetry there is a relation between modular weights and $U(1)_X$ charges. The
soft scalar masses are then strongly correlated with Yukawa matrices. The
implications for FCNC are discussed.


title: Excitation Fields in a Superconducting Global String

abstract:
  A model of a straight superconducting global cosmic string is examined in a
setting wherein the string supports a charge/current pulse described by a
travelling wave along the string. Linearized field equations are obtained for
fluctuations of the scalar and vector fields of the theory, and a set of
approximate particular solutions are found for the case in which the linear
charge density and the current of the string have equal magnitudes. Although
the equations of motion seem to suggest that the scalar and vector excitation
fields are massive inside the string core, the particular solutions show that
they behave as effectively massless fields which propagate at the speed of
light along the string along with the primary charge/current pulse. The effect
of the mass parameter is to modulate the radial profile of the excitation
fields. The vector excitation field generates radial and angular components for
both the electric and magnetic fields, but the particular solutions do not
describe the emission or absorption of electromagnetic radiation from the
string.


title: Multiscale Technicolor and the Zbb-bar Vertex

abstract:
  We estimate the correction to the Zbb-bar vertex arising from the exchanges
of the sideways extended technicolor (ETC) boson and the flavor-diagonal ETC
boson in the multiscale walking technicolor model. The obtained result is too
large to explain the present data. However, if we introduce a new self-
interaction for the top quark to induce the top quark condensate serving as the
origin of the large top quark mass, the corrected R_b=Gamma_b/Gamma_h can be
consistent with the recent LEP data. The corresponding correction to
R_c=Gamma_c/Gamma_h is shown to be negligibly small.


title: Dissipation and Decoherence in Mean Field Theory

abstract:
  The time evolution of a closed system of mean fields and fluctuations is
Hamiltonian, with the canonical variables parameterizing the general
time-dependent Gaussian density matrix of the system. Yet, the evolution
manifests both quantum decoherence and apparent irreversibility of energy flow
from the coherent mean fields to fluctuating quantum modes. Using scalar QED as
an example we show how this collisionless damping and decoherence may be
understood as the result of {\em dephasing} of the rapidly varying fluctuations
and particle production in the time varying mean field.