title:
Natural Hadronic Degrees of Freedom for an Effective QCD Action in the
  Front Form

abstract:
  On the one hand any effective action of the QCD,
$S[\pi,\,\rho,\,\omega,\ldots,N,\,\overline N,\,\Delta^{3/2},\ldots]$, would
involve, at least in principle, a tower of hadronic fields of all spins; on the
other hand the front form of the field theory has emerged as an appropriate
framework to investigate the high energy behaviour of many systems. Motivated
by these simple considerations we present a systematic formalism which
explicitly provides the front form fields appropriate for constructing a
$S[\pi,\,\rho,\,\omega,\ldots,N,\,\overline N,\,\Delta^{3/2},\ldots]$. Further,
a transformation matrix $\Omega(j)$ is constructed which determines how the
front form hadronic fields superimpose to yield the more familiar instant form
fields. Explicit results for the front form hadronic fields up to spin two are
catalogued in appendixes. For spin one half, the $\Omega(1/2)$ coincides with
the celebrated ``Melosh transformation.'' The formalism, without explicitly
invoking any wave equations, reproduces spin one half front-form results of
Lepage and Brodsky, and Dziembowski.


title: Anomalies in the effective theory of heavy quarks

abstract:
  The question of the anomalies in the effective theory of heavy quarks is
investigated at two different levels. Firstly, it is shown that none of the
symmetries of this effective theory contains an anomaly. The existence of a new
`$ \gamma _ 5 $'-symmetry is pointed out and shown to be also anomaly free.
Secondly, it is shown that the chiral anomaly of QCD is not reproduced in the
effective lagrangian for the heavy quarks, thus contradicting 't Hooft's
anomaly matching condition. Finally, the effective theory of heavy quarks is
derived from the QCD lagrangian in such a way that the terms leading to the
anomaly are included. For this derivation the generating functional method is
used.


title: Non-Gaussian Corrections to Higgs Mass in Autonomous lambda phi**4

abstract:
  Recent calculations in one-loop and Gaussian appro- ximation, using the
so-called autonomous renormalization scheme, indicate a comparatively massive,
narrow Higgs excitation at about 2 TeV. Here I show that this result
qualitatively persists in the framework of a post-Gaussian variational
approximation for the pure O(N)-symmetric phi**4-theory for N>1. The method is
based on nonlinear transformations of path-integral variables, and the
optimization amounts to a Schwinger-Dyson-type summation of diagrams. In the
case of O(4), for example, I find M_Higgs = 2.3 TeV, compared to 1.9 TeV and
2.1 TeV in 1-loop and Gaussian approximation, respectively.


title: Asymptotic Freedom and the Emergence of QCD

abstract:
  I describe our understanding of the strong interactions at the end of the
1960's and the impact of the experiments on deep inelastic scattering. I recall
the steps that lead from the attempts to understand these experiments to the
discovery of asymptotic freedom in 1973 and the subsequent rapid emergence,
development and acceptance of the non-Abelian gauge theory of color (QCD) as
the theory of the strong interactions.


title: Hidden Local Symmetry at One Loop

abstract:
  We show that one-loop corrections with the hidden gauge boson loop preserve
in the low energy limit all the successful tree level predictions of the hidden
local symmetry in the SU(2)${}_L$$\times$SU(2)${}_R$$/$SU(2)${}_V$ chiral
Lagrangian. Most amazingly, the $\rho$ meson dominance of the pion
electromagnetic form factor survives the one-loop corrections at any momentum,
if and only if we take the parameter choice $a=2$. For the choice $a=1$
(``vector limit"), $a$ is not renormalized ($Z_a=1$) and no deviation from
$a=1$ is induced by the loop effects of the hidden gauge bosons. Actually,
$a=1$ is a nontrivial ultraviolet fixed point.


title:
Large-$N_c$ Higher Order Weak Chiral Lagrangians for Nonleptonic and
  Radiative Kaon Decays

abstract:
  In pure chiral perturbation theory (ChPT) the couplings of higher order
Lagrangian terms are running parameters and hence can be determined only
empirically from various low-energy hadronic processes. While this scenario
works well for strong interactions, it is unsatisfactory for nonleptonic and
radiative nonleptonic weak interactions: It is impossible, from the outset, to
determine all unknown higher-order chiral couplings by experiment; theory is
tested only by certain chiral constraints rather than by its quantitative
predictions. Based on a QCD-motivated model for $p^4$ strong chiral Lagrangian
valid in the limit of large $N_c$, one can derive large-$N_c$ fourth-order
effective chiral Lagrangians for $\Delta S=1$ nonleptonic weak interactions and
radiative weak transitions. Applications to
$K\ri\pi\pi\pi,~K\ri\pi\gamma\gamma$, and $K\ri\pi\pi\gamma$ are discussed.


title: Wiggly Relativistic Strings

abstract:
  We derive the equations of motion for general strings, i.e. strings with
arbitrary relation between tension $\tau$ and energy per unit length
$\epsilon$. The renormalization of $\tau$ and $\epsilon$ that results from
averaging out small scale wiggles on the string is obtained in the general case
to lowest order in the amount of wiggliness. For Nambu-Goto strings we find
deviations from the equation of state $\epsilon \tau = {\rm constant}$ in
higher orders. Finally we argue that wiggliness may radically modify the gauge
cosmic string scenario.


title: More About Discrete Gauge Anomalies

abstract:
  I discuss and extend several results concerning the cancellation of discrete
gauge anomalies. I show how heavy fermions do not decouple in the presence of
discrete gauge anomalies. As a consequence, in general, cancellation of
discrete gauge anomalies cannot be described merely in terms of low energy
operators involving only the light fermions. I also discuss cancellation of
discrete gauge anomalies through a discrete version of the Green-Schwarz (GS)
mechanism as well as the possibility of discrete gauge R-symmetries and their
anomalies.
  Finally, some phenomenological applications are discussed. This includes
symmetries guaranteeing absence of FCNC in two-Higgs models and generalized
matter parities stabilizing the proton in the supersymmetric standard model. In
the presence of a discrete GS mechanism or/and gauge R-symmetries, new
possibilities for anomaly free such symmetries are found.


title: Generalized Gluon Currents and Applications in QCD

abstract:
  We consider the process containing two quark lines and an arbitrary number of
gluons in a spinor helicity framework. A current with two off-shell gluons
appears in the amplitude. We first study this modified gluon current using
recursion relations. The recursion relation for the modified gluon current is
solved for the case of like-helicity gluons. We apply the modified gluon
current to compute the amplitude for $q \bar q \rightarrow q \bar q gg \cdots
g$ in the like-helicity gluon case.


title: Multiphoton Production at High Energies in the Standard Model I

abstract:
  We examine multiphoton production in the electroweak sector of the Standard
Model in the high energy limit using the equivalence theorem in combination
with spinor helicity techniques. We obtain recursion relations for currents
consisting of a charged scalar, spinor, or vector line that radiates $n$
photons. Closed form solutions to these recursion relations for arbitrary $n$
are presented for the cases of like-helicity and one unlike-helicity photon
production. We apply the currents singly and in pairs to obtain amplitudes for
processes involving the production of $n$ photons with up to two unlike
helicities from a pair of charged particles. The replacement of one or more
photons by transversely polarized $$Z$-bosons is also discussed.


title: Multiphoton Production at High Energies in the Standard Model II

abstract:
  We examine multiphoton production in the electroweak sector of the Standard
Model in the high energy limit using the equivalence theorem in combination
with spinor helicity techniques. We utilize currents consisting of a charged
scalar, spinor, or vector line that radiates $n$ photons. Only one end of the
charged line is off shell in these currents, which are known for the cases of
like-helicity and one unlike-helicity photons. We obtain a wide variety of
helicity amplitudes for processes involving two pairs of charged particles by
considering combinations of four currents. We examine the situation with
respect to currents which have both ends of the charged line off-shell, and
present solutions for the case of like-helicity photons. These new currents may
be combined with two of the original currents to produce additional amplitudes
involving Higgs, longitudinal $Z$ or neutrino pairs.


title: QCD non-leading corrections to weak decays in the dimensional scheme

abstract:
  We compute the next to leading QCD corrections to weak four fermion
interactions introducing a scheme that does not require an explicit definition
of $\gamma_5$ in $d$ dimensions. This scheme reduces greatly the difficulties
in calculating the two loop anomalous dimensions; we recover the results
obtained in the previous literature.


title:
Complementarity of Resonant and Nonresonant Strong WW Scattering at SSC
  and LHC

abstract:
  Signals and backgrounds for strong $WW$ scattering at the SSC and LHC are
considered. Complementarity of resonant signals in the $I=1$ $WZ$ channel and
nonresonant signals in the $I=2$ \wpwp channel is illustrated using a chiral
lagrangian with a $J=1$ \qrho resonance. Results are presented for purely
leptonic final states in the $W^{\pm}Z$, $W^+W^+ + W^-W^-$, and $ZZ$ channels.


title: A Non-Standard Quark Model and the Mass Difference $\Xi^- - \Xi^0$

abstract:
  We show that a highly unconventional theory, based on the 16 dimensional
(${3\over2}$,${3\over2}$) irreducible representation of O(4), fits the masses
of the baryons
$\Xi^-$,$\Xi^0$,$\Sigma^-$,$\Sigma^0$,$\Sigma^+$,$\Lambda$,$p$,$n$ and the
leptons $\mu$,$e$,$\nu_\mu$,$\nu_e$ to within current experimental error, yet
yields a prediction substantially different from that of Coleman and Glashow,
namely $\Xi^- - \Xi^0 < 6.1$ MeV. We discuss the ramifications of this very
non-standard model in the hope to stimulate improved measurements of the $\Xi^-
- \Xi^0$ mass difference.


title: Finite Unified Models

abstract:
  We present phenomenologically viable $SU(5)$ unified models which are finite
to all orders before the spontaneous symmetry breaking. In the case of two
models with three families the top quark mass is predicted to be 178.8 GeV.


title: Gaugino condensation in 4-D superstring models

abstract:
  We study the possibility that supersymmetry is broken via a gaugino
condensate in four dimensional string theories. We derive an effective
low-energy theory describing the Goldstone mode associated with the R-symmetry
breaking driven by gaugino condensation and show that this gives a description
of gaugino condensation equivalent, at tree level, to other effective
Lagrangian approaches based on the symmetries of the theory. A study of the
mass gap equation shows that non-perturbative effects favour the appearance of
a gaugino condensate. By minimizing the effective potential describing both the
condensate and the moduli determining the gauge coupling constant and radius of
compactification we show that large hierarchy may occur between the gravitino
mass and the Planck mass with the existence of only one gaugino condensate.
Associated with this is a determination of the fine structure constant and the
compactification scale.


title: The Cheshire Cat Bag Model: Color Anomaly and $\eta'$ Properties

abstract:
  We show that color can leak from a QCD bag if we allow for pseudoscalar
isoscalar singlet ($\eta'$) coupling at the surface. To enforce total
confinement of color an additional boundary term is suggested. New relations
between the $\eta'$ mass and decay constant and the QCD gluon condensates are
derived and compared with the empirical parameters.


title: Solar Neutrino Data, Solar Model Uncertainties and Neutrino Oscillations

abstract:
  We incorporate all existing solar neutrino flux measurements and take solar
model flux uncertainties into account in deriving global fits to parameter
space for the MSW and vacuum solutions of the solar neutrino problem.


title: Signatures for Heavy $\bf Z'$ Bosons at Hadron Colliders

abstract:
  We discuss three promising diagnostic probes of the couplings of a possible
heavy $Z'$ boson at hadron colliders: the forward-backward asymmetry into
leptons, the rare decay $Z' \ra W^{\pm} \ell^{\mp} \nu$, and associated
production $pp \ra Z'W,\; Z'Z$. A general model-independent framework is
proposed for interpreting these and other data. Clean tests of whether a new
$W'$ couples to right-handed currents, of the ratio $g_R/g_L$ of gauge
couplings, and of the non-abelian vertex in left-right symmetric models are
described.


title:
The effective potential at finite temperature in the left-right
  symmetric model

abstract:
  We obtain the effective potential at finite temperature within the left-right
symmetric model. We take the Higgs sector to consist of two doublets and
calculate its finite temperature effective potential up to the order of
``ring-diagrams'', using analogous techniques to those employed in the
derivation of the effective potential in the Standard Model. We find that two
first order phase transitions can exist, one at the $SU(2)_R$ breaking scale,
the other at the usual $SU(2)_L\otimes U(1)_Y$ breaking scale. Even though more
parameters are present than the standard model, we find that the electroweak
phase transition is still too weak to allow baryon asymmetry to survive the
transition, if the lower bound of the Higgs boson mass from experiment is
adhered to.


title: Dilatons in the topological soliton model for the hyperons

abstract:
  We show that the predicted hyperon masses in the topological soliton model
are very sensitive to the value of the gluon condensate parameter that appears
when the scale invariance and trace anomaly of QCD are taken into account by
introduction of a dilaton field. This contrasts with the insensitivity of the
soliton properties to the dilaton coupling. In order that the predicted strange
and charmed hyperon spectra agree with the empirical ones the gluon condensate
parameter has to be about (400 MeV)$^4$, which agrees with the result obtained
from QCD sum rules. This implies that the bag formed by the scalar field must
be very shallow.


title:
Instability of Bubbles Near the Hadron--Quark-Gluon-Plasma Phase
  Transition

abstract:
  The small surface tension of the interface between hadronic and
quark-gluon-plasma domains, along with a negative curvature tension, implies
that the uniform plasma is unstable against spontaneous formation of hadronic
bubbles. We furthermore show that spherical bubbles are not stable against
small perturbations.


title: Variational Method for Studying Solitons in the KdV equation

abstract:
  We use a class of trial wave functions which are generalizations of gaussians
to study single soliton approximate analytic solutions to the KdV equations.
The variational parameters obey a Hamiltonian dynamics obtained from the
Principle of Least Action. We get extremely accurate approximate single soliton
solutions including their time dependence using this method.


title: Computing Spectral Densities in Finite Temperature Field Theory

abstract:
  Convenient Cutkosky-like diagrammatic rules for computing the spectral
densities of arbitrary two-point correlation functions in finite temperature
field theory are derived. The approach is based on an explicit analytic
continuation of imaginary-time Feynman diagrams and avoids the complications of
real-time finite temperature perturbation theory. The application of this
method to the perturbative evaluation of transport coefficients is briefly
discussed.


title: Improving the Effective Potential

abstract:
  A general procedure is presented how to improve the effective potential by
using the renormalization group equation (RGE) in MS bar scheme. If one knows
the L-loop effective potential and the RGE coefficient functions up to
(L+1)-loop level, this procedure gives an improved potential which satisfies
the RGE and contains all of the leading, next-to-leading,... , and
L-th-to-leading log terms.


title: Improving the Effective Potential:Multi-Mass-Scale Case

abstract:
  Previously proposed procedure for improving the effective potential by using
renormalization group equation (RGE) is generalized so as to be applicable to
any system containing several different mass scales. If one knows L-loop
effective potential and (L+1)-loop RGE coefficient functions, this procedure
gives an improved potential which satisfies the RGE and contains all of the
leading, next-to-leading,..., and L-th-to-leading log terms. Our procedure here
also clarifies how naturally the so-called effective field theory can be
incorporated in the RGE in MS bar scheme.


title: Observing Electroweak Symmetry Breaking at the SSC

abstract:
  In this talk we survey the SSC signals and backgrounds for the physics of
electroweak symmetry breaking. We study the process $pp \rightarrow WWX$ and
compute the rate for the ``gold-plated'' signals $W^\pm \rightarrow \ell^\pm
\nu$ and $Z \rightarrow \ell^+\ell^-$ $(\ell = e,\mu)$ for a wide variety of
models. We use a forward jet tag and central jet veto to suppress the
standard-model backgrounds. In this way we estimate the SSC sensitivity to the
physics of electroweak symmetry breaking. (Revised version contains style file
ichep.sty.)


title: ETC With a GIM Mechanism

abstract:
  We construct an extended technicolor model of quarks and leptons which
preserves a GIM mechanism. Furthermore, there is only a minimal technicolor
sector, in accordance with recent precision measurements of electroweak
parameters. We also show how to incorporate custodial SU(2) and massless
neutrinos into such a model.


title: Testing ETC Generation of the Top Quark Mass

abstract:
  We consider constraints on models in which a top quark mass is generated
through unenhanced extended technicolor interactions. The deviation in the
$\rho$ parameter from unity and $B$--$\overline{B}$ mixing could be large, but
given the uncertainties in strong dynamics and variations in the parameters of
models, no conclusive statement can be given. We conclude that the low
technicolor scale which is required to generate the top quark mass is not ruled
out.


title:
Spontaneously Broken Technicolor and the Dynamics of Virtual Vector
  Technimesons

abstract:
  We propose spontaneously breaking technicolor, thus liberating techniquarks
and suppressing large resonance contributions to the electroweak $S$ parameter.
The dynamics is modeled by a fermion bubble approximation to a single massive
techni--gluon exchange potential. This contains a Nambu--Jona-Lasinio model
with additional interactions. ``Virtual'' vector mesons occur and contribute to
$S$, and their effects are studied. Models of broken technicolor are discussed.


title: Post-Gaussian Varioational Method for the Nonlinear Schrodinger Equation

abstract:
  Gaussians to study soliton behavior and blowup in the nonlinear Schrodinger
equation in arbitrary dimension d and with arbitrary nonlinearity parameter
kappa


title: Uncertainties in Coupling Constant Unification

abstract:
  The status of coupling constant unification in the standard model and its
supersymmetric extension are discussed. Uncertainties associated with the input
coupling constants, $m_{t}$, threshold corrections at the low and high scales,
and possible nonrenormalizable operators are parametrized and estimated. A
simple parametrization of a general supersymmetric new particle spectrum is
given. It is shown that an effective scale $M_{SUSY}$ can be defined, but for a
realistic spectrum it may differ considerably from the typical new particle
masses. The implications of the lower (higher) values of $\alpha_{s}(M_{Z})$
suggested by low-energy ($Z$-pole) experiments are discussed.


title: The SSC: Programme and Searches for New Particles

abstract:
  Talk presented at the Trieste Workshop on the Search for New Elementary
Particles: Status and Prospects.


title: On an asymptotic estimate of the $n$-loop correction in perturbative QCD

abstract:
  A recently proposed method of estimating the asymptotic behaviour of QCD
perturbation theory coefficients is critically reviewed and shown to contain
numerous invalid mathematical operations and unsubstantiated assumptions. We
discuss in detail why this procedure, based solely on renormalization group
(RG) considerations and analyticity constraints, cannot lead to such estimates.
We stress the importance of correct renormalization scheme (RS) dependence of
any meaningful asymptotic estimate and argue that the unambiguous summation of
QCD perturbation expansions for physical quantities requires information from
outside of perturbation theory itself.


title: Proton Decay

abstract:
  The status of proton decay is described, including general motivations for
baryon number violation, and the present and future experimental situation.
Grand unification with and without supersymmetry is considered, including
possible evidence from coupling constant unification and implications for
proton decay and neutrino mass.


title:
Flavor Asymmetry of the Nucleon Sea: Consequences for Dilepton
  Production

abstract:
  Parton distributions derived from a chiral quark model that generates an
excess of down quarks and antiquarks in the proton's sea satisfactorily
describe the measured yields of muon pairs produced in proton-nucleus
collisions. Comparison of dilepton yields from hydrogen and deuterium targets
promises greater sensitivity to the predicted flavor asymmetry.


title: Gravitational Smearing of Minimal Supersymmetric Unification Predictions

abstract: A short and mean paper.


title:
Phenomenological Aspects of Supersymmetric Standard Models without Grand
  Unification

abstract:
  When the GUT relation on gaugino masses is relaxed, the mass and composition
of the lightest neutralino are different from those in the GUT case. We discuss
its phenomenological implications on the relic abundance of the neutralinos and
on superparticle searches. In particular, we focus on the case where the
neutral component of Winos dominates the lightest neutralino. It turns out the
Wino-LSP is not a candidate for the dark matter.


title:
Calculable Upper Limit on the Mass of the Lightest Higgs Boson in Any
  Perturbatively Valid Supersymmetric Theory

abstract:
  We show that there is a calculable upper limit on the mass of the lightest
Higgs boson in any supersymmetric theory that remains perturbative up to a high
scale . There are no restrictions on the Higgs sector, or the gauge group or
particle content. We estimate the value of the upper limit to be $m_{\hcirc} <
146$ GeV for 100 GeV < $M_t$ < 145 GeV, from all effects except possibly
additional heavy fermions beyond top (which could increase the limit by 0-20
GeV if any existed); for $M_t$ > 145 GeV the limit decreases monotonically. We
expect to be able to decrease the value of the upper limit by at least a few
percent by very careful analysis of the conditions. It is not normal in models
for the actual mass to saturate the upper limit.


title: How Effective is the Effective Potential?

abstract:
  Motivated by bubble nucleation in first order phase transitions, we question
the validity of the effective potential for inhomogeneous configurations. In an
attempt to get some insight into the importance of derivative terms, we analyze
a simple model, a kink in (1+1) dimensions and zero temperature. We evaluate
the energy shift from the quantum fluctuations about the non-uniform background
({\it i.e.}, the effective action) and compare it to the energy from the
effective potential. Our results clearly show that for inhomogeneous
configurations it may be inadequate to omit derivative terms and confine
oneself to the effective potential. We then couple the kink field to an
additional scalar field and perform the same comparison. The addition of the
second field allows us to vary the mass of the fluctuations and their coupling
to the underlying kink. If the mass of the second field is large, it does not
feel the inhomogeneities in the kink field and consequently does not give rise
to important derivative corrections in the effective action. In contrast, if
the mass is small, derivative terms are significant and the effective potential
fails. In the latter regime we can, however, rely on the Born approximation to
calculate the effective action.


title: Zeros of Tree-Level Amplitudes at Multi-Boson Thresholds

abstract:
  Propagation of particles with emission of arbitrary number of identical
bosons all being at rest is considered. It is shown that in certain models the
tree-level amplitudes for production of $n$ scalar bosons by two incoming
particles are all equal to zero at the threshold starting from some small
number $n$. In particular this nullification occurs for production of massive
scalars by two Goldstone bosons in the linear sigma model for $n > 1$ and also
for production of Higgs bosons in the Standard Model by gauge bosons and/or by
fermions, provided that the ratia of their masses to that of the Higgs boson
take special discrete values.


title: Scaling limit of a non-relativistic model

abstract:
  I calculate the structure function for scattering from the two-body bound
state in its lowest level in a non-relativistic model of confined scalar
``quarks'' of masses $m_A$ and $m_B$. The scaling limit in $x={\bf
q}^2/2(m_A+m_B)q^0$ exists and is non-vanishing only for the values
$x=m_A/(m_A+m_B)$ and $x=m_B/(m_A+m_B)$ which correspond to the fractions of
the momentum of the two-body system carried by each of the ``quarks.'' In the
scaling limit, the interference from scattering off of the two ``quarks''
vanishes. Thus the scaling limit of this model agrees with the parton picture.


title:
Chern-simon type photon mass from fermion electric dipole moments at
  finite temperature in 3+1 dimensions

abstract:
  We study the low energy effective field theory of fermions with electric and
magnetic dipole moments at finite temperature. We find that at one loop there
is an interaction term of the Chern-Simon form ${\cal L_I}=m_\mu\>A_\nu {\tilde
F}^{\mu\nu}$. The four vector $m_\mu \simeq d_i \mu_i m_i^2
~{\partial_\mu}\>(ln T)$ is interpreted as a Chern- Simon type mass of photons,
which is determined by the electric (magnetic) dipole moments $d_i$ ($\mu_i$)
of the fermions in the vacuum polarisation loop diagram. The physical
consequence of such a photon mass is that, photons of opposite circular
polarisations, propagating through a hot medium, have different group
velocities. We estimate that the time lag between the arrival times of the left
and right circularly polarised light signals from pulsars. If the light
propagates through a hot plasma (where the temperature in some regions is $T
\sim 100 MeV$) then the time lag between the two circularly polarised signals
of frequency $\omega$ will be $\Delta t(\omega) \simeq 10^{-6} /\omega$. It may
be possible to observe this effect in pulsar signals which propagate through
nebula at high temperatures.


title: The Perturbative Onset of Multiparticle Production in Weak Interactions

abstract:
  We use perturbation theory to estimate the energy scale beyond which
multiparticle final states become a dominant feature of high energy weak
interactions. Using estimates from a weak parton model and comparing two, three
and four body final states we deduce that multiparticle states become important
at energy scales in the range 10**7 - 10**9 GeV.


title: Nuclear Axial-Charge Transitions in Chiral Perturbation Theory

abstract:
  We develop a systematic chiral perturbation expansion for the calculation of
meson-exchange currents in nuclei and apply the formalism to nuclear axial
currents. We summarize the principal results of such a calculation to one loop
order on nuclear axial-charge transitions which provides a strong support to
the conjecture of ``chiral filter phenomenon" in nuclear medium. The use of
heavy baryon chiral perturbation theory enables us to obtain a remarkably
simple result valid next to the leading order in chiral counting. The dominant
role of a soft-pion exchange in axial-charge transitions in heavy nuclei is
confirmed. An important, {\it albeit} indirect, consequence of our result on
the empirically observed enhancement in axial-charge transitions in heavy
nuclei is pointed out.


title:
Avalanche in the Valley (Fermions, Anomaly and Unitarity in High-Energy
  Electroweak Interactions)

abstract:
  Problems related to fermions, unitarity and chiral anomaly in high energy
electroweak interactions, are investigated. Particular attention is paid to the
correct functional integration over fermion fields in the background of
instanton-anti\-instanton type configurations. This leads to an expansion of
correlation functions in terms of a small parameter, $\rho/R$, when the
instanton-antiinstanton separation ($R$) is large compared to their sizes
($\rho$). Applying such a method to widely discussed cases of fermion-number
violation in the electroweak theory, we conclude that there are no theoretical
basis for expecting anomalous cross sections to become observable at energies
in the $10$ TeV region.


title: The fermion mass problem

abstract:
  In this talk I review the `puzzles' associated with the fermion mass matrices
and describe some recent attempts to resolve them, at least partially. Models
which attempt to explain the observed mass hierarchy as arising from radiative
corrections are discussed. I then scrutinize possible inter--relations among
quark and lepton masses and the mixing angles in the context of grand unified
theories. It is argued that the absence of CP violation in the strong
interaction sector (the strong CP problem) may also have its origin in the
structure of the quark mass matrices; such a resolution does not invoke
approximate global $U(1)$ symmetries resulting in the axion. Arguments in favor
of tiny neutrino masses are summarized (the solar neutrino puzzle, atmospheric
neutrino problem) and ways to accommodate them naturally are described.


title: Heavy top quark from Fritzsch mass matrices

abstract:
  It is shown, contrary to common belief, that the Fritzsch ansatz for the
quark mass matrices admits a heavy top quark. With the ansatz prescribed at the
supersymmetric grand unified (GUT) scale, one finds that the top quark may be
as heavy as 145 GeV, provided that tan$\beta$ (the ratio of the vacuum
expectation values of the two higgs doublets) $\gg 1$. Within a
non-supersymmetric GUT framework with two (one) light higgs doublets, the
corresponding approximate upper bound on the top mass is $120~ (90)$ GeV. Our
results are based on a general one--loop renormalization group analysis of the
quark masses and mixing angles and are readily applied to alternative mass
matrix ans\"{a}tze.


title:
Radiative Origin of the Fermion Mass Hierarchy: A Realistic and
  Predictive Approach

abstract:
  The up-down splitting within quark families increases with the family number:
m_u ~ m_d, m_c > m_s, m_t >> m_b. We show an approach that realizes this
feature of the spectrum in a natural way. We suggest that the mass hierarchy is
first generated by radiative effects in a sector of heavy isosinglet fermions,
and then projected to the ordinary light fermions by means of a seesaw mixing.
The hierarchy appears then inverted in the light fermion sector. We present a
simple left-right symmetric gauge model in which the P- and CP-parities and an
isotopical "up-down" symmetry are softly (or spontaneously) broken in the Higgs
potential. Experimentally consistent predictions are obtained. The Cabibbo
angle is automatically in the needed range: Theta_C ~ 0.2. The top quark is
naturally heavy, but not too heavy: m_t < 150 GeV.


title:
Static and Dynamic Critical Phenomena at a Second Order QCD Phase
  Transition

abstract:
  In QCD with two flavors of massless quarks, the chiral phase transition is
plausibly in the same universality class as the classical four component
Heisenberg antiferromagnet. Therefore, renormalization group techniques
developed in the study of phase transitions can be applied to calculate the
critical exponents which characterize the scaling behaviour of universal
quantities near the critical point. This approach to the QCD phase transition
has implications both for lattice gauge theory and for heavy ion collisions.
Future lattice simulations with longer correlation lengths will be able to
measure the various exponents and the equation of state for the order parameter
as a function of temperature and quark mass which we describe. In a heavy ion
collision, the consequence of a long correlation length would be large
fluctuations in the number ratio of neutral to charged pions. Unfortunately, we
show that this phenomenon will not occur if the plasma stays close to
equilibrium as it cools. If the transition is far out of equilibrium and can be
modelled as a quench, it is possible that large volumes of the plasma with the
pion field correlated will develop, with dramatic phenomenological
consequences. }


title: Intermittency and Particle Correlations: Theory

abstract:
  We review recent theoretical developments in understanding the intermittency
phenomenon observed in high-energy leptonic, hadronic and nuclear collisions.
In particular, we discuss self-similar cascading and QCD parton showers, models
with models with phase transitions, and the three-dimensional statistical field
theory of multiparticle density fluctuations. University


title:
Analytical on-shell QED results: 3-loop vacuum polarization, 4-loop
  beta-function and the muon anomaly

abstract:
  We present the results of analytical calculations of the 3-loop contributions
to the asymptotic photon vacuum polarization function, in the on shell scheme,
and of the 4-loop contributions to the on shell QED beta-function. These are
used to evaluate various 4-loop and 5-loop contributions to the muon anomaly.
Our analytical contributions to (g-2)_\mu differ significantly from previous
numerical results. A very recent numerical re-evaluation of 4-loop muon-anomaly
contributions has yielded results much closer to ours.


title: Generation Mass Hierarchy in Superstring Derived Models

abstract:
  I discuss the problem of generation mass hierarchy in the context of
realistic superstring models which are constructed in the free fermionic
formulation. These models correspond to models which are compactified on
$Z_2\times Z_2$ orbifold. I suggest that the hierarchy among the generations
results from horizontal symmetries, which arise from the compactification. In
particular, I show that in a class of free fermionic standard--like models, the
suppression of the mass terms for the lightest generation is a general, and
unambiguous, characteristic of these models. I show that the mixing between the
generations is suppressed due to the horizontal symmetries. I conclude that
these models may potentially explain the generation mass hierarchy.


title: Tau Decay Puzzles and Possible Light Gluinos

abstract:
  The relation of the strong coupling constant as measured in tau decay to
other low energy determinations is considered with special attention to its
impact on the question of the possible existence of light gluinos.


title: Non--perturbative evidence for non--decoupling of heavy fermions

abstract:
  We investigate, using a $1/N$ expansion, the behavior of a parameter in the
scalar--fermion sector of the standard model that shows perturbative
non--decoupling as the fermion becomes heavy. This low energy parameter is
related to the $S$ parameter defined through the $W_3-B$ vacuum polarization
tensor. We obtain the leading $1/N$ contribution to this parameter that, if
expanded perturbatively, collapses to its constant one--loop result; remarkably
all the higher--order terms in the series vanish. Non--perturbatively, however,
we find that as the mass of the fermion approaches the built--in cutoff scale
of the theory --- the triviality scale --- the parameter is highly dependent on
the implementation of the cutoff; it is non--universal, and shows
non--decoupling.


title:
Quark model calculation of $\eta \to l^+ l^-$ to all orders in the bound
  state relative momentum

abstract:
  The electromagnetic box diagram for the leptonic decays of pseudoscalar
mesons in the quark model is evaluated to all orders in ${\bf p} / m_q$, where
${\bf p}$ is the relative three-momentum of the quark-antiquark pair and $m_q$
is the quark mass. We compute $B_P \equiv \Gamma(\eta \to l^+ l^-) /
\Gamma(\eta \to \gamma\gamma)$ using a popular nonrelativistic (NR) harmonic
oscillator wave function, and with a relativistic momentum space wave function
that we derive from the MIT bag model. We also compare with a calculation in
the limit of extreme NR binding due to Bergstr\"om. Numerical calculations of
$B_P$ using these three parameterizations of the wave function agree to within
a few percent over a wide kinematical range. We find that the quark model leads
in a natural way to a negligible value for the ratio of dispersive to
absorptive parts of the electromagnetic amplitude for $\eta \to \mu^+ \mu^-$
(unitary bound). However we find substantial deviations from the unitary bound
in other kinematical regions, such as $\eta,\pi^0 \to e^+ e^-$. These quark
models yield $B(\eta \to \mu^+\mu^-) \approx 4.3 \times 10^{-6}$, within errors
of the recent SATURNE measurement of $5.1 \pm 0.8 \times 10^{-6}$, $B(\eta \to
e^+ e^-) \approx 6.3 \times 10^{-9}$, and $B(\pi^0 \to e^+ e^-) \approx 1.0
\times 10^{-7}$.


title: Universal Evolution of CKM Matrix Elements

abstract:
  We derive the two-loop evolution equations for the Cabibbo-Kobayashi-Maskawa
matrix. We show that to leading order in the mass and CKM hierarchies the
scaling of the mixings $|V_{ub}|^2$, $|V_{cb}|^2$, $|V_{td}|^2$, $|V_{ts}|^2$
and of the rephase-invariant CP-violating parameter $J$ is universal to all
orders in perturbation theory. In leading order the other CKM elements do not
scale. Imposing the constraint $\lambda _b=\lambda _{\tau}$ at the GUT scale
determines the CKM scaling factor to be $\simeq 0.58$ in the MSSM.


title:
Topological Defect Models of Structure Formation After the COBE
  Discovery of CMB Anisotropies

abstract:
  The COBE satellite has discovered anisotropies in the cosmic microwave
background (CMB) consistent with a scale invariant spectrum of density
perturbations. As reviewed in this lecture, topological defect models of
structure formation generically produce such a spectrum. We give a summary of
the cosmic string and global texture models, focusing on distinct observational
signatures in large-scale structure surveys and in the microwave background. It
is shown that the amplitude of the CMB quadrupole detected by COBE is in good
agreement with the predictions of the cosmic string model.


title: A Bound on the Energy Loss of Partons in Nuclei

abstract:
  We derive a quantum mechanical upper bound on the amount of radiative energy
loss suffered by high energy quarks and gluons in nuclear matter. The bound
shows that the nuclear suppression observed in quarkonium production at high
$x_F$ cannot be explained in terms of energy loss of the initial or final
parton states. We also argue that no nuclear suppression is expected in the
photoproduction of light hadrons at large $x_F$.


title: Intermittency and Multidimensional Correlations

abstract:
  We review recent experimental results on intermittency and multidimensional
particle correlations in high-energy leptonic, hadronic and nuclear collisions.
We discuss different theoretical models, including self-similar cascading and
QCD parton showers, models with phase transitions and the three-dimensional
statistical field theory for multiparticle density fluctuations.


title:
Three Dimensional Statistical Field Theory for Density Fluctuations in
  Heavy-Ion Collsiions

abstract:
  A statistical field theory of particle production is presented using a
gaussian functional in three dimensions. Identifying the field with the
particle density fluctuation results in zero correlations of order three and
higher, while the second order correlation function is of a Yukawa form. A
detailed scheme for projecting the theoretical three-dimensional correlation
onto data of three and fewer dimensions illustrates how theoretical predictions
are tested against experimental moments in the different dimensions. An example
given in terms of NA35 parameters should be testable against future NA35 data.


title: Weak Radiative Hyperon Decays in Chiral Perturbation Theory

abstract:
  The parity-conserving $a$ and parity-violating $b$ amplitudes for weak
radiative hyperon decay are studied using chiral perturbation theory. The
imaginary parts of $a$ and $b$ are computed using unitarity. The real part of
$b$ is dominated by a one-loop infrared divergent graph which is computed. The
real part of $a$ has a large theoretical uncertainty and cannot be calculated
reliably. Counterterms for the $a$ and $b$ amplitudes are classified using
$CPS$ symmetry. The experimental values for decay widths and asymmetries are
consistent with theory, with the exception of the asymmetry parameter for the
$\Sigma^+ \rightarrow p \gamma$ decay.


title:
Radiative corrections to the decay H==>hh in the Minimal Supersymmetric
  Standard Model

abstract:
  We set up a suitable renormalization programme for the one-loop computation
of the decay rate Gamma(H==>hh) in the Minimal Supersymmetric extension of the
Standard Model. We then perform an explicit diagrammatic calculation, including
the full contributions from top, bottom, stop and sbottom loops. We find that,
for tan(beta) close to 1, and m_H greater than or approximately equal to 2 m_t,
the results can significantly differ from those previously obtained in the
effective potential approach. However, the latter method remains a good
approximation in the region of parameter space which is most relevant for H
searches at large hadron colliders.


title: New QCD Effects at Large x

abstract:
  In heavy quark production at large Feynman $x$ there are two hardness scales,
one given by the heavy quark pair mass $\M^2$\ and the other by
$\Lambda_{QCD}^2/(1-x)$. When these two scales are comparable, the twist
expansion of Perturbative QCD breaks down. We discuss the dynamics in this new
QCD limit, where $\mu^2=\M^2(1-x)$ is held fixed as $\M^2\to \infty$. New
diagrams are found to contribute, which can enhance the cross section above
that expected for leading twist. The heavy quarks are produced by a peripheral
scattering on the target of hardness $\mu^2$. This leads, in particular, to a
nuclear target dependence of $A^{2/3}$ at small $\mu$. Qualitatively, the
dynamics in the new limit agrees with earlier phenomenological models of
``intrinsic'' heavy quark production.


title: Heavy-Quark Baryons as Skyrmions

abstract:
  I discuss recent development on the description of heavy-quark (such as
charmed and bottom) baryons as one or more heavy mesons "wrapped" by a
skyrmion. Amazingly enough, such a description naturally arises when
light-quark chiral symmetry and heavy-quark spin symmetry are incorporated in
an effective Lagrangian. I interpret the resulting spectrum in terms of
nonabelian induced (Berry) potentials in analogy to diatomic molecular systems.


title: Nonperturbative QCD efects in weak hadronic decays

abstract:
  QCD-based analysis of nonfactorizable parts of weak nonleptonic amplitudes is
reported.
  Nonperturbative effects due to soft gluon exchange play a key role leading to
the emergence of a dynamical rule of discarding $1/N_c$ corrections.


title: Search for Heavy Leptons at Hadron Colliders

abstract:
  Four models are considered which contain heavy leptons beyond the three
families of the standard model. Two are fourth-generation extensions of the
standard model in which the right-handed heavy leptons are either isosinglets
or in an isodoublet; the other two are motivated by the aspon model of CP
violation. In all these models, the heavy neutrino can either be heavier than,
or comparable in mass to, the charged lepton leading to the possibility that
the charged lepton is very long-lived. Production cross section and signatures
for the heavy leptons are computed for the SSC and LHC.


title: Search for Dileptons in Z decay

abstract:
  The lepton family number violation $Z$ boson decay, $Z \to e^-e^-\mu^+\mu^+$
or $e^+e^+\mu^-\mu^-$, mediated by a dilepton, e.g. from an SU(15) theory, is
calculated. The branching ratio of such exotic decay for allowed dilepton
masses is found to be smaller than 10$^{-10}$.


title: New Contribution to Coherent neutralino-Nucleus Scattering

abstract:
  We discuss coherent scattering between supersymmetric neutralinos and nuclei
via an effective neutralino-gluon interaction. We identify two new classes of
diagrams which are not treated in the existing literature. These occur at the
same order of perturbation theory as the previously considered diagrams. The
new contributions can be numerically important, and can even dominate the total
amplitude. This affects the clculation fo event rates in experiments searching
for direct or indirect evidence of cosmic relic neutralinos.


title: A More Effective Potential

abstract:
  In theories with spontaneous symmetry breaking, the conventional effective
potential possesses a defective loop expansion. For such theories, the exact
effective potential $V(\phi_c,T)$ is real and convex, but its perturbative
series is complex and concave at small $\phi_c$ and $T$. A more effective
potential is available.


title: A Comment on the Strong Interactions of Color-Neutral Technibaryons

abstract:
  We estimate the cross section for the scattering of a slow, color-neutral
technibaryon made of colored constituents with nuclei. We find a cross section
of order $A^2\ 10^{-45}$ cm$^2$, where $A$ is the atomic number of the nucleus.
Even if technibaryons constitute the dark matter in the galactic halo, this is
too small to be detected in future underground detectors.


title:
Heavy to Light Semileptonic Transitions in the Heavy Quark Effective
  Theory

abstract:
  The scaling behavior of semileptonic form-factors in Heavy to Light
transitions is studied in the Heavy Quark Effective Theory. In the case of
$H\rightarrow \pi e\nu$ it is shown that the same scaling violations affecting
the heavy meson decay constant will be present in the semileptonic
form-factors.


title: Critical Constraints on Chiral Hierarchies

abstract:
  We consider the constraints that critical dynamics places on models with a
top quark condensate or strong extended technicolor (ETC). These models require
that chiral-symmetry-breaking dynamics at a high energy scale plays a
significant role in electroweak symmetry breaking. In order for there to be a
large hierarchy between the scale of the high energy dynamics and the weak
scale, the high energy theory must have a second order chiral phase transition.
If the transition is second order, then close to the transition the theory may
be described in terms of a low-energy effective Lagrangian with composite
``Higgs'' scalars. However, scalar theories in which there are more than one
$\Phi^4$ coupling can have a {\it first order} phase transition instead, due to
the Coleman-Weinberg instability. Therefore, top-condensate or strong ETC
theories in which the composite scalars have more than one $\Phi^4$ coupling
cannot always support a large hierarchy. In particular, if the
Nambu--Jona-Lasinio model solved in the large-$N_c$ limit is a good
approximation to the high-energy dynamics, then these models will not produce
acceptable electroweak symmetry breaking.


title:
Threshold Effects on Heavy Quark Production in $\gamma\gamma$
  Interactions

abstract:
  The exchange of gluons between heavy quarks produced in $e^+e^-$ interactions
results in an enhancement of their production near threshold. We study QCD
threshold effects in $\gamma\gamma$ collisions. The results are relevant to
heavy quark production by beamstrahlung and laser back-scattering in future
linear collider experiments. Detailed predictions for top, bottom and charm
production are presented.


title: On the High $T$ Phase Transition in the Gauged $SU(2)$ Higgs Model

abstract:
  We study the effective field theory of a weakly coupled 3+1d gauged $\phi^4$
type model at high temperature. Our model has $4N$ real scalars
  ($N$ complex Higgs doublets) and a gauge group $SU(2)$ which is spontaneously
broken by a nonzero scalar field $vev$ at zero temperature.
  We find, for sufficiently large $N$, that the transition from the high
temperature symmetry restoring phase to the low temperature phase can be either
first order or second order depending on the ratio of the gauge coupling to the
scalar self coupling.


title:
Tevatron Mass Limits for Heavy Quarks Decaying via Flavor Changing
  Neutral Current

abstract:
  The dimuon and dielectron data from the Tevatron $\bar pp$ collider are used
to probe for heavy quarks, which decay dominantly via flavour changing neutral
current. Depending on whether the $FCNC$ decay occurs at the tree or loop
level, one gets a lower mass limit of 85 or 75 GeV. The former applies to
singlet, vector doublet and mirror type quarks while the latter applies to a
lefthanded quark doublet of the fourth generation.


title:
The Simplest, String-Derivable, Supergravity Model and its Experimental
  Predictions

abstract:
  We present the simplest, string-derivable, supergravity model and discuss its
experimental consequences. This model is a new string-inspired flipped $SU(5)$
which unifies at the string scale $M_U=10^{18}\GeV$ due to the introduction of
an additional pair of \r{10},\rb{10} flipped $SU(5)$ representations which
contain new intermediate scale `gap' particles. We study various model-building
issues which should be addressed in string-derived incarnations of this model.
We focus our study on the no-scale supergravity mechanism and explore
thoroughly the three-dimensional parameter space of the model ($m_{\tilde
g},m_t,\tan\beta$), thus obtaining several simple relationships among the
particle masses, such as: $m_{\tilde q}\approx m_{\tilde g}$, $m_{\tilde
e_L}\approx m_{\tilde\nu}\approx0.30 m_{\tilde g}$, $m_{\tilde
e_R}\approx0.18m_{\tilde g}$, and $m_{\chi^0_2}\approx2m_{\chi^0_1}\approx
m_{\chi^\pm_1}$. In a strict interpretation of the no-scale supergravity
scenario we solve for $\tan\beta$ as a function of $m_t$ and $m_{\tilde g}$,
and show that $m_t$ determines not only the sign of the Higgs mixing parameter
$\mu$ but also whether the lightest Higgs boson mass is above or below
$100\GeV$. We also find that throughout the parameter space the neutralino
relic abundance is within observational bounds ($\Omega_\chi h^2_0\lsim0.25$)
and may account for a significant portion of the dark matter in the Universe.


title: Structure functions for large $x$ and renormalization of Wilson loops

abstract:
  We discuss the relation between partonic distributions near the phase space
boundary and Wilson loop expectation values calculated along paths partially
lying on the light-cone. Due to additional light-cone singularities,
multiplicative renormalizability for these expectation values is lost.
Nevertheless we establish the renormalization group equation for the light like
Wilson loops and show that it is equivalent to the evolution equation for the
physical distributions. By performing a two-loop calculation we verify these
properties and show that the universal form of the splitting function for large
x originates from the cusp anomalous dimension of Wilson loops.


title: On the COBE Discovery - for Pedestrians

abstract:
  A recent discovery by the COBE satellite is presented, and its importance
discussed in the context of the physics of the early Universe. The various
implications for our understanding of the structure of the Universe are
outlined.


title:
Flavour Distributions in the Nucleons: SU(2) Sea Asymmetry or Isospin
  Symmetry Breaking?

abstract:
  The Gottfried sum rule violation reported by the New Muon Collaboration(NMC)
was interpreted as indication for a flavour asymmetry of the sea quark in the
nucleons. We investigate the alternative possibility that isospin symmetry
between the proton and the neutron is breaking. We examine systematically the
consequences of this possibility for several processes, namely, neutrino deep
inelastic scattering, charged pion Drell-Yan process, proton Drell-Yan process,
and semi-inclusive deep inelastic scattering, and conclude that a decision
between the two alternative explanations is possible.


title: Bell's Inequality and $\tau$-Physics at LEP

abstract:
  In this talk given at the TAU92 Workshop, Columbus, OH, Sept. 92, we
summarize results presented in more detail in a recent paper by S. Abel, M.
Dittmar and the author where we gave a general proof that Bell's inequality can
not be tested at a collider experiment. In particular, a measurement of
correlated tau-spins at LEP does not constitute a test of local realistic
theories via Bell's inequality. The central point of the argument is that such
tests, where the spins of two particles are inferred from a scattering
distribution, can always be described by a local hidden variable theory. In
response to questions at the workshop we go beyond the paper and show that an
old experiment involving the measurement of the correlated spins of the two
photons emitted in positronium decay via Compton-scattering is also not a
viable test of Bell's inequality.


title: R-Parity Violation at HERA

abstract:
  We summarize the signals at HERA in supersymmetric models with explicitly
broken R-parity. As the most promising case, we consider in detail the resonant
production of single squarks through an operator $L_1Q_i{ \bar D}_j$, a
production process analogous to that for leptoquarks. However, the dominant
decay of the squark to a quark and a photino leads to a very different
experimental signature. We examine in particular the case where the photino
decays to a positron and two quarks. Using a detailed Monte-Carlo procedure we
obtain a discovery limit in the squark mass---Yukawa coupling plane. HERA can
discover a squark for a mass as large as $270 \gev$ and for an R-parity
violating Yukawa coupling as small as $5.8 \times 10^{-3}$.


title:
QCD Corrections to the Light Higgs Boson Decay into a Charm- Anticharm
  or Bottom- Antibottom Pair within the Minimal Supersymmetric Model

abstract:
  We present the results of the contributions to the decay rate of the lightest
Higgs particle into a charm-anticharm and bottom-antibottom pair within the
minimal supersymmetric standard model when scalar quarks and a gluino are taken
within the relevant loop diagrams. We show that in the case where the vacuum
expectation values of the Higgs particles obey the condition $v_1\ll v_2$\ the
scalar quarks and gluino change the decay rate by not more than a few per cent.
These small contributions make it difficult to distinguish the Higgs particle
of the standard model from the supersymmetric one.


title: SO(10) Cosmic Strings and Baryon Number Violation

abstract:
  SO(10) cosmic strings formed during the phase transition Spin(10)
$\rightarrow$ SU(5) $\times{\cal Z}_2$ are studied. Two types of strings ---
one effectively Abelian and one non-Abelian --- are constructed and the string
solutions are calculated numerically. The non-Abelian string can catalyze
baryon number violation via the ``twisting'' of the scalar field which causes
mixing of leptons and quarks in the fermion multiplet. The non-Abelian string
is also found to have the lower energy possibly for the entire range of the
parameters in the theory. Scattering of fermions in the fields of the strings
is analyzed, and the baryon number violation cross section is calculated. The
role of the self-adjoint parameters is discussed and the values are computed.


title: Ansatz for Quark, Charged Lepton, and Neutrino Masses in SUSY GUTS

abstract:
  We extend a fermion mass matrix Ansatz by Giuduce to include neutrino masses.
The previous predictions are maintained. With two additional parameters, a
large Majorana neutrino mass and a hierarchy factor, we have seven {\it
further} low energy predictions: the masses of the neutrinos, the mixing angles
and the phase in the leptonic sector. We choose a reasonable hierarchy of
Majorana masses and fit the overall mass scale according to a solution of the
solar neutrino problem via the MSW mechanism, which is in agreement with the
$^{37}Cl$, Kamiokande, and GALLEX data. We then also obtain a cosmologically
interesting tau-neutrino mass.


title: Cosmology and Astrophysics 1992

abstract:
  I review recent developments in cosmology and astrophysics relevant to
particle physics, focussing on the following questions: What's new in 1992?
What have we learned since the last ICHEP meeting in 1990? and What are the
prospects for the future? AMong the topics explicitly discussed are: COBE,
Large Scale Structure, and Dark Matter; Bib Bang Nucleosynthesis; the Solar
Neutrino Problem; and High Energy Gamma Ray PHysics.


title:
Systematic Study of Fermion Masses and Mixing Angles in Horizontal SU(2)
  Gauge Theory

abstract:
  Despite its great success in explaining the basic interactions of nature, the
standard model suffers from an inability to explain the observed masses of the
fundamental particles and the weak mixing angles between them. We shall survey
a set of possible extensions to the standard model, employing an SU(2)
``horizontal'' gauge symmetry between the particle generations, to see what
light they can shed on this problem.


title: Evidence For SUSY from GUTS? Evidence For GUTS From SUSY!

abstract:
  We review the theoretical and experimental status of minimal grand unified
theories (GUTS), contrasting the failure of minimal non-supersymmetric $SU(5)$
with the success of the minimal supersymmetric $SU(5)$ and minimal
supersymmetric Flipped $SU(5)\times U(1)$ models. We show that a reasonable
value for the universal soft supersymmetry-breaking gaugino mass,
$45\GeV<m_{1/2}<1\TeV$, and a $1-\sigma$ range of the other inputs constrains
the strong coupling, $\as>.114$. We define the supersymmetric standard model
(SSM), the minimal supersymmetric extension of the standard model with gauge
coupling unification and universal soft supersymmetry-breaking at the
unification scale, as a baseline model for unified theories. We review the
structure of the allowed parameter space of the SSM and suggest sparticle
spectroscopy as the experimental means to determine the parameters of the SSM
and search for departures from the baseline SSM.


title:
Self-consistent Improvement of the Finite Temperature Effective
  Potential

abstract:
  We present a self-consistent calculation of the finite temperature effective
potential for $\lambda \phi^4$ theory, using the composite operator effective
potential in which an infinite series of the leading diagrams is summed up. Our
calculation establishes the proper form of the leading correction to the
perturbative one-loop effective potential.


title:
Scattering with Baryon Number Violation -- The Case of Higgs Particle
  Production --

abstract:
  \noindent A formalism based on path-integral expression of time-evolution
operator during tunneling at a finite energy proposed by the authors is applied
to $SU(2)$ gauge-Higgs system to produce Higgs particles with $\Delta B=1$.
Instead of starting from instanton tunneling at the zero energy, a classical
bounce solution giving sphaleron (instanton) action at high (low) energies is
used as the tunneling configuration. Fourier transform of the bounce
configuration in coherent state expression at the entrance and exit of the
tunneling plays an important role. Numerical results at various energies for
$M_H/M_W=1 \sim 2 $ are given. Though the cross section with $\Delta B=1$
results from a severe cancellation of several large quantities in the leading
order as occured in the instanton calculus, it seems unlikely that the cross
section grows as largely as to reach unitarity bound at energies $E \leq
E_{sph}$. It is pointed out that the actual value $g^2=0.418$ of the $SU(2)$
gauge coupling constant may be too large to take the weak coupling limit.}


title: On the role of vector mesons in topological soliton stability

abstract:
  Isospin one vector mesons (in particular the $\rho$) are usually described as
massive Yang-Mills particles in the chiral Lagrangian. We investigate some
aspects of an alternative approach in the soliton sector. It is found that the
soliton is stable in very much the same way as with the $\omega$-meson and that
spontaneous parity violating classical solutions do not exist. The formulation
in terms of antisymmetric tensors is shown to be canonically related to a
vector field description provided the Skyrme term is added to the latter.


title: Neutrino Mixing due to a Violation of the Equivalence Principle

abstract:
  Massless neutrinos will mix if their couplings to gravity are flavor
dependent, i.e., violate the principle of equivalence. Because the
gravitational interaction grows with neutrino energy, the solar neutrino
problem and the recent atmospheric neutrino data may be simultaneously
explained by violations at the level of 1E-14 to 1E-17 or smaller. This
possibility is severely constrained by present accelerator neutrino experiments
and will be preeminently tested in proposed long baseline accelerator neutrino
experiments.


title: "Vortex Solution in a Multi-Higgs System and Its Physical Implication,"

abstract:
  Classical vortex solutions in $(1+2)$-dimensional multi-Higgs systems are
studied. In particular the existence of such a solution requires equal
characteristic lengths and a specific relation between the ratio of the two
Higgs vacuum expectation values and the couplings in the Higgs potential, if
$\lambda_3\neq 0$.


title: On Constraints for Heavy-Meson Form Factors

abstract:
  We examine the recent work of de Rafael and Taron where model-independent
bounds on the Isgur-Wise function are presented. We first argue that the bounds
cannot hold in as much generality as implied. We show that the effects of
resonances omitted in their discussion (such as heavy-heavy ``onium'' states
below threshold) modify the bound. The resulting bound is much weaker but may
be useful where the size of the additional contribution may be computed or
estimated.


title: A Possible Measurement of CP-Violation in B0-decays by ATLAS on LHC

abstract:
  A possibility to measure CP-violation in B0-decays by ATLAS experiment was
investigated. With one year of running at luminosity 10^33 cm-2s-1 with a muon
pt-trigger threshold of 20GeV and rapidity coverage eta<2.5 of the tracking
detector the rate of 1490 events B0->J/psi->mumupipi can be reached.


title: Quantum Corrections to Nucleation Rates

abstract:
  In this paper we show how to compute in a consistent way nucleation rates in
field theory at finite temperatures, with metastable vacuum. Using the
semiclassical approach in field theory at finite temperature we show that the
prefactor term can be calculated explicitly (in the thin-wall approximation)
and that the same provides exponential finite temperature quamtum corrections
to nucleation rates, when fluctuations around the bubble field configuration
are considered.


title: Thermal Fluctuations and Validity of the 1-Loop Effective Potential

abstract:
  We examine the validity of the 1-loop approximation to the effective
potential at finite temperatures and present a simple test for its reliability.
As an application we study the standard electroweak potential, showing that for
a Higgs mass above 70 GeV, and afirly independent of the top mass (with $m_{t}
> 90 GeV$, the 1-loop approximation is no longer valid for temperatures in the
neighborhood of the critical temperature.


title:
Critical Temperature for the $\LAMBDA (\PHI^{4})_{4}$ Theory within the
  $\DELTA$ -Expansion

abstract:
  We apply the $\delta$-expansion perturbation scheme to the $\lambda \phi_{4}$
self-interacting scalar field theory in 3+1 D at finite temperature. In the
$\delta$-expansion the interaction term is written as $\lambda (\phi^{2})^{1 +
\delta}$ and $\delta$ is considered as the perturbation parameter. We compute,
in this perturbation approach, the renormalized mass at finite temperature from
which we get the critical temperature. The results are compared with the usual
loop-expansion at finite temperature.


title:
Small Angle Polarization in High Energy P--P Scattering Through
  Nonperturbative Chiral Symmetry Breaking

abstract:
  We show that a large anomalous contribution due to nonperturbative
instanton-like gluonic field configurations to the axial charge of the proton
implies high-energy spin effects in $p-p$ elastic scattering. This is the same
mechanism which is responsible for anomalous baryon number violation at high
energy in the standard model. We compute the proton polarization due to these
effects and we show that it is proportional to the center-of-mass scattering
angle with a universal (energy-independent) slope of order unity.


title: Analyticity and the Isgur-Wise Function

abstract:
  We reconsider the recent derivation by de Rafael and Taron of bounds on the
slope of the Isgur-Wise function. We argue that one must be careful to include
cuts starting below the heavy meson pair production threshold, arising from
heavy quark-antiquark bound states, and that if such cuts are properly
accounted for then no constraints may be derived.


title: On the Limits of Chiral Perturbation Theory

abstract:
  We consider the relation between the breakdown scale of chiral perturbation
theory, $\Lambda_\chi$, for large values of $N$ (flavor), and the scale
associated with ``new" physical thresholds. This question is addressed using
both the linear $\sigma$ model and an asymptotically-free gauge theory to
describe the high energy dynamics. It is suggested that the massive physical
threshold could be well above $\Lambda_\chi$.


title:
SU(16) grandunification: breaking scales, proton decay and neutrino
  magnetic moment

abstract:
  We give a detailed renormalization group analysis for the SU(16) grandunified
group with general breaking chains in which quarks and leptons transform
separately at intermediate energies. Our analysis includes the effects of Higgs
bosons. We show that the grandunification scale could be as low as $\sim
10^{8.5}$ GeV and give examples where new physics could exist at relatively low
energy ($\sim 250$ GeV). We consider proton decay in this model and show that
it is consistent with a low grandunification scale. We also discuss the
possible generation of a neutrino magnetic moment in the range of $10^{-11}$ to
$10^{-10}\mu_B$ with a very small mass by the breaking of the embedded
SU(2)$_\nu$ symmetry at a low energy.


title: Final-State Interaction of Longitudinal Vector Bosons

abstract:
  In the standard Higgs model of electroweak symmetry breaking, the Higgs boson
is associated with both vector-boson and fermion mass generation. In contrast,
we discuss a two-Higgs-doublet model in which these masses are associated with
two different scalar bosons. We show that the Higgs boson associated with
vector-boson mass generation produces a {\it dip\/} in the cross section for
$t\bar t\to ZZ$ via a final-state interaction. Such a dip will be difficult to
observe at the LHC/SSC.


title: Simply Modeling Meson HQET

abstract:
  A simple relativistic model of heavy-quark-light-quark mesons is proposed. In
an expansion in inverse powers of the heavy quark mass we find that all zeroth
and first order heavy quark symmetry relations are satisfied. The main results
are: - the difference between the meson mass and the heavy quark mass plays a
significant role even at zeroth order; - the slope of the Isgur-Wise function
at the zero recoil point is typically less than $-1$; - the first order
correction to the pseudoscalar decay constant is large and negative; - the four
universal functions describing the first order corrections to the semileptonic
decay form factors are small; - these latter corrections are quite insensitive
to the choice of model parameters, and in particular to the effects of
hyperfine mass splitting.


title: Violation of the Bjorken Sum Rule in QCD

abstract:
  We show that the Bjorken sum rule for the first moment of the polarized
nucleon structure function $g_1$ is not necessarily satisfied in QCD if the
axial anomaly is taken into account. We argue that nonperturbative QCD effects
should lead to a violation of the sum rule of the order of the percentage
isospin violation in current quark masses.


title:
Proposed Tests for Minimal SU(5) Supergravity at Fermilab, Gran Sasso,
  SuperKamiokande, and LEP

abstract:
  A series of predictions are worked out in order to put the minimal $SU(5)$
supergravity model under experimental test. Using the two-loop gauge coupling
renormalization group equations, with the inclusion of supersymmetric threshold
corrections, we calculate a new value for the proton decay rate in this model
and find that SuperKamiokande and Gran Sasso should see the proton decay mode
$p\to\bar\nu K^+$ for most of the allowed parameter space. A set of physically
sensible assumptions and the cosmological requirement of a not too young
Universe give us a rather restrictive set of allowed points in the parameter
space, which characterizes this model. This set implies the existence of
interesting correlations among various masses: either the lightest chargino and
the next-to-lightest neutralino are below $\approx100\GeV$ (and therefore
observable at the Tevatron) or the lightest Higgs boson is below
$\approx50\GeV$ (and therefore observable at LEP I-II). These tests are crucial
steps towards selecting the correct low-energy effective supergravity model. We
also comment on the compatibility of the model with $\sin^2\theta_w(M_Z)$
measurements as a function of $\alpha_3(M_Z)$.


title: Casimir Energy in the Skyrme Model

abstract:
  The so called Casimir energy embodies the O($(N_c)^0$) contribution to the
skyrmion mass according to the semi-classical expansion theory of solitons. We
claim that this contribution can be accurately estimated despite the fact that
some of the counterterms, provided in principle by chiral perturbation theory,
are not known in practice. Using $\zeta$ function techniques we show that
$E_{cas}=E_{cas}(\mu)+E_{ct}(\mu)$ where $E_{cas}(\mu)>>E_{ct}(\mu)$ because it
incorporates all the zero-mode contributions and it can be exactly calculated.
Our results confirm that the fourth order Skyrme lagrangian does not seem to
provide a correct description of the lightest baryons as solitons. We show that
a simple extension to order six gives, on the contrary, good results without
tuning the parameters of the chiral lagrangian.


title:
Radiatively Corrected Bound on the Light Higgs Mass in a Minimal Non
  Minimal Supersymmetric Standard Model

abstract:
  The neutral Higgs sector of the Minimal non Minimal Supersymmetric Standard
Model is considered. By effective potential and R.G.E. supported method; an
upper bound of the lightest Higgs is analysed. From the request of
perturbativity of the coupling in the superpotential, adding the leading stop
top contributions, the absolute bound of $\sim 130$ GeV for $90 GeV < m_t< 180
GeV$ and $M_{\tilde{t}} \simeq 1000 $ GeV is derived. The interesting
dependence on $m_t$ for $\tan{\beta} \to 1$ is discussed .


title: Fermi-Dirac corrections to relic abundances

abstract:
  We derive an equation for the evolution of the number density of a massive
particle species in the early Universe, which correctly accounts for the
Fermi-Dirac (FD) statistics. The FD-corrections are sizable and potentially
important if the decoupling from the thermal equilibrium takes place at
temperatures of the order of, or less than the mass of the particle. This is
the case e.g.\ for a few MeV tau neutrino with the ordinary weak interactions.


title:
Implications of LEP Results for SO(10) Grandunification with Two
  Intermediate Stages

abstract:
  We consider the breaking of the grand unification group $SO(10)$ to the
standard model gauge group through several chains containing two intermediate
stages. Using the values of the gauge coupling constants at scale $M_Z$ derived
from recent LEP data, we determine the range of their intermediate and
unification scales. In particular, we identify those chains that permit new
gauge structure at relatively low energy $(\sim 1\, {\rm TeV})$.


title: Anomalous prompt photon production in hadronic collisions at low-$x_T$

abstract:
  We investigate the discrepancy that exists at low-$x_T=2p_T/\sqrt{s}$ between
the next--to--leading order QCD calculations of prompt photon production and
the measured cross section. The central values of the measured cross section
are of order 100\% larger than QCD predictions in this region. It has been
suggested that the bremsstrahlung contribution may account for this
discrepancy. The quark fragmentation function $D_{\gamma/q}(z)$ has not been
measured and an exactly known asymptotic form is normally used in calculations.
We examine the effect of much larger fragmentation functions on the QCD
predictions. After illustrating the effect of the large fragmentation functions
in some detail for recent CDF data at $\sqrt{s}$=1.8~TeV, we perform a $\chi^2$
fit to 8 prompt photon data sets ranging in CMS energy from 24~GeV to 1.8~TeV.
While a large fragmentation function normalization may prove to play an
important role in resolving the discrepancy, the present theoretical and
experimental uncertainties prevent any definite normalization value from being
determined.


title: A Separate Higgs?

abstract:
  We investigate the possibility of a multi-Higgs doublet model where the
lightest neutral Higgs boson ($h^0$) decouples from the fermion sector. We are
partially motivated by the four $\ell^+\ell^-\gamma\gamma$ events with
$M_{\gamma\gamma}\simeq60$\,GeV recently observed by the L3 collaboration,
which could be a signal for $Z\to (Z^*\to \ell^+\ell^-)+(h^0\to \gamma\gamma)$.
Collider signatures for the additional physical Higgs bosons present in such
models are discussed.


title: COBE and SUSY

abstract:
  We show that supersymmetry automatically leads to density fluctuations
$\Delta T/T\sim6\times10^{-6}$ in agreement with the recent COBE measurement.


title:
Lepton Number Violating Radiative $W$ Decay in Models with R-parity
  Violation

abstract:
  Models with explicit R-parity violation can induce new rare radiative decay
modes of the $W$ boson into single supersymmetric particles which also violate
lepton number. We examine the rate and signature for one such decay,
$W\rightarrow \tilde l\gamma$, and find that such a mode will be very difficult
to observe, due its small branching fraction, even if the lepton number
violating coupling in the superpotential is comparable in strength to
electromagnetism. This parallels a similar result obtained earlier by Hewett in
the case of radiative $Z$ decays.


title: Multiscalar production amplitudes beyond threshold

abstract:
  We present exact tree-order amplitudes for $H^* \to n~H$, for final states
containing one or two particles with non-zero three-momentum, for various
interaction potentials. We show that there are potentials leading to tree
amplitudes that satisfy unitarity, not only at threshold but also in the above
kinematical configurations and probably beyond. As a by-product, we also
calculate $2\to n$ tree amplitudes at threshold and show that for the unbroken
$\phi^4$ theory they vanish for $n>4~$, for the Standard Model Higgs they
vanish for $n\ge 3~$ and for a model potential, respecting tree-order
unitarity, for $n$ even and $n>4~$. Finally, we calculate the imaginary part of
the one-loop $1\to n$ amplitude in both symmetric and spontaneously broken
$\phi^4$ theory.


title:
Properties of perturbative multi-particle amplitudes in $\phi^k$ and
  $O(N)$ theories

abstract:
  Threshold amplitudes are considered for multi-particle production in $\phi^k$
and $O(N) ~\phi^4$ theories. It is found that the disappearance of tree-level
threshold amplitudes of $2$ on-shell particles producing a large number of
particles occurs in $\phi^k$ theory only for $k=3$ and $k=4$. The one-loop
correction to the threshold amplitude for a highly virtual scalar particle
decaying into $n$ particles in an $O(N)$ model is derived.


title: Effective Hadron Dynamics: From Meson Masses to the Proton Spin Puzzle

abstract:
  We construct a three flavor chiral Lagrangian of pseudoscalars and vectors
with special emphasis on the symmetry breaking terms. Comparing tree level two
and three point functions with experiment allows us to first, fix the
parameters of the model (including the light quark mass ratios) and second, to
predict $m(K^{*+})-m(K^{*\circ}),\, \Gamma(K^*\rightarrow K\pi)$ and
$\Gamma(\phi\rightarrow K {\overline K})$. The last mentioned quantities come
out reasonably well, in contrast to an ``ordinary" $SU(3)$ treatment. For this
purpose we need ``second order" symmetry breakers involving the vector fields
analogous to those needed for the chiral perturbation theory program with only
pseudoscalars. An improved description of the $\eta-\eta^\prime$ system is also
given. We then use the soliton sector of this improved chiral Lagrangian to
investigate some aspects of baryon physics which are especially sensitive to
symmetry breaking. For this purpose a fairly elaborate ``cranking" techinque is
employed in connection with the collective Hamiltonian. In addition to the
``strong" baryon mass spectrum a careful investigation is made of the
non-electromagnetic part of the neutron-proton mass difference. This work is
needed to improve our previous estimates concerning the two component approach
to the ``proton spin" puzzle. We find that both the ``matter" and ``glue"
contributions are small but they do tend to cancel each other.


title: Debajyoti Choudhury

abstract:
  Gluon fusion into a very heavy neutrino pair by Higgs exchange is shown to
lead to substantial production cross sections at $pp$ supercolliders even
without any extra generation of quarks. Rates are calculated for scalar as well
as pseudoscalar Higgs. The angular correlation between dileptons emerging from
the decays of the neutrinos shows distinctive features for Dirac and Majorana
neutrinos as well as for scalar and pseudoscalar Higgs.


title: Antimatter in the Universe

abstract:
  Cosmological models which predict a large amount of antimatter in the
Universe are reviewed. Observational signatures and searches for cosmic
antimatter are briefly considered. A short discussion of new long range forces
which might be associated with matter and antimatter is presented.


title:
Some Properties of Amplitudes at Multi Boson Thresholds in Spontaneously
  Broken Scalar Theory

abstract:
  It is shown that in a $\lambda \phi^4$ theory of one real scalar field with
spontaneous breaking of symmetry a calculation of the amplitudes of production
by a virtual field $\phi$ of $n$ on-mass-shell bosons all being exactly at rest
is equivalent in any order of the loop expansion to a Euclidean space
calculation of the mean field of a kink-type configuration. Using this
equivalence it is found that all the $1 \to n$ amplitudes have no absorptive
part at the thresholds to any order of perturbation theory. This implies
non-trivial relations between multi-boson threshold production amplitudes. In
particular the on-mass-shell amplitude of the process $2 \to 3$ should vanish
at the threshold in all loops. It is also shown that the factor $n!$ in the $1
\to n$ amplitudes at the threshold is not eliminated by loop effects.


title:
Looking for the gluonic EMC effect in associated $J/\psi$ + $\gamma $
  production

abstract:
  We study the associated production of $ J/\psi\ + \gamma $ in fixed-target
experiments with nuclear targets as well as at the relativistic heavy-ion
collider (RHIC). We find that this process affords a very clean probe of
$\rho_g$, the ratio of gluon density in a heavy nucleus to that of a proton.
The combined $x$ range thus available can be used to discriminate between the
predictions of different models of the EMC effect for $\rho_g$.


title:
Semileptonic Inclusive B--Decays and the Determination of $|V_{ub}|$
  from QCD Sum Rules

abstract:
  We calculate the electron spectrum of semileptonic decays of B-mesons into
non-charmed hadrons. The shape of the spectrum obtained from QCD sum rules is
in general agreement with quark model calculations. At high electron energies
the decrease of the spectrum is less steep than predicted by Altarelli et al.
Our analysis yields a total decay rate $\Gamma(B\to X_u e\bar\nu) = (6.8\pm
2.0) 10^{13} |V_{ub}|^2 {s}^{-1}$. For the spectrum integrated over electron
energies in the interval $2.4{ GeV}\leq E_e \leq 2.6\mbox{\ GeV}$ in the
laboratory frame we obtain $\Gamma(B\to X_u e \bar\nu)= (5.0\pm 1.6) 10^{12}
|V_{ub}|^2 {s}^{-1}$. Estimating all sorts of theoretical uncertainties, we
obtain $|V_{ub}| = 0.003\pm 0.001$ for the $b \to u$ weak transition matrix
element from the new CLEO-data.


title: Intrinsic Parity of the $(j,0)\oplus(0,j)$ Mesons

abstract:
  Contrary to the usual belief, by carefully examining the operation of parity
transformation on the $(1,0)\oplus(0,1)$ mesons in the generalized canonical
representation, we establish that the $(j,0)\oplus(0,j)$ meson-antimeson pair
have {\it opposite} intrinsic parity. This opens up the possibility that while
the particles without an internal structure may utilize one representation of
the Lorentz group, phenomenologies of composite particles may exploit a
different representation. As such (perhaps, only some of) the meson structures
beyond the standard $q\,\overline {Q}$ may exploit the $(j,0)\oplus(0,j)$
generalized canonical representation of the Lorentz group -- this would result
in a meson and the associated antimeson to manifest themselves in {\it
different} partial waves.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CONSTRUCTIVE COMMENTS WELCOME, AS ALWAYS
  D. V. A.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


title: New flavor changing interactions in extended gauge models

abstract:
  A new class of flavor changing (FC) neutral interactions can arise in models
based on extended gauge groups (rank $>$4) when new charged fermions are
present together with new neutral gauge bosons. In some cases the FC couplings
to a new $Z_1$ are expected to be sizeable, implying that the $Z_1$ mass must
be large enough as to explain the observed suppression of FC transitions.
Concentrating on E$_6$ models and assuming for the FC parameters a
theoretically natural range of values, I show that in most cases the presence
of a $Z_1$ much lighter than 1 TeV is unlikely.


title: Strong and Electromagnetic Decays of the Baryon Decuplet

abstract:
  We discuss the strong and radiative decays of the decuplet of baryon
resonances to the baryon octet in chiral perturbation theory. We comment on the
implications for the polarisability of the nucleon.


title: Effective Lagrangian for Heavy and Light Mesons: Semileptonic Decays

abstract:
  We introduce an effective lagrangian including negative and positive parity
heavy mesons containing a heavy quark, light pseudoscalars, and light vector
resonances, with their allowed interactions, using heavy quark spin-flavour
symmetry, chiral symmetry, and the hidden symmetry approach for light vector
resonances. On the basis of such a lagrangian, by considering the allowed weak
currents and by including the contributions from the nearest unitarity poles we
calculate the form factors for semileptonic decays of $B$ and $D$ mesons into
light pseudoscalars and light vector resonances. The available data, together
with some additional assumptions, allow for a set of predictions in the
different semileptonic channels, which can be compared with those following
{}from different approaches. A discussion of non-dominant terms in our
approach, which attempts at including a rather complete dynamics, will however
have to wait till more abundant data become available.


title: Constraints on New Physics from the Higgs and Top Masses

abstract:
  Triviality and vacuum stability bounds on the Higgs and top quark masses in a
rather general class of supersymmetric extensions of the Standard Model are
compared with the corresponding bounds without supersymmetry. Due to generic
differences of those bounds we find that experimental knowledge of the Higgs
and top masses may provide a ``pointer'' into one of these directions.
Depending on the values of the masses, however, both scenarios or none could
also be allowed.


title: On the Nucleon Distribution Amplitude: The Heterotic Solution

abstract:
  We present a new nucleon distribution amplitude which amalgamates features of
the Chernyak-Ogloblin-Zhitnitsky model with those of the Gari-Stefanis model.
This "heterotic" solution provides the possibility to have asymptotically a
small ratio \hbox{$\vert G_{M}^{n}\vert/G_{M}^{p}\le 0.1$}, while fulfilling
most of the sum-rule requirements up to the third order. Using this nucleon
distribution amplitude we calculate the electromagnetic and weak nucleon form
factors, the transition form factor $\gamma p \Delta^{+}$ and the decay widths
of the charmonium levels $^3S_{1}$, $^3P_{1}$, and $^3P_{2}$ into $p\bar p$.
The agreement with the available data is remarkable in all cases.


title:
Analysis of $\Delta^{+}(1232)$ Isobar Observables, with Improved Quark
  Distribution Amplitudes

abstract:
  A model distribution amplitude for the $\Delta^{+}(1232)$ isobar is proposed,
derived on the basis of the QCD sum-rule calculations of Farrar et al. combined
with those of Carlson and Poor. The transition form factor $\gamma p\Delta^{+}$
is calculated modeling the proton by selected distribution amplitudes.
Furthermore, predictions are made for some exclusive charmonium decays into
$\Delta\bar{\Delta}$. The obtained results are compared with other theoretical
models and with the available data.


title: Exact Results on e+ e- --> e+ e- + 2 Photons at SLC/LEP Energies

abstract:
  We use the spinor methods of the CALKUL collaboration, as realized by Xu,
Zhang and Chang, to calculate the differential cross section for e+ e- --> e+
e- + 2 photons for c.m.s. energies in the SLC/LEP regime. An explicit complete
formula for the respective cross section is obtained. The leading log
approximation is used to check the formula. Applications of the formula to high
precision luminosity calculations at SLC/LEP are discussed.


title: Rigorous QCD Predictions for Decays of P-Wave Quarkonia

abstract:
  We present a new factorization theorem for the decay rates of P-wave states
of heavy quarkonia. Infrared logarithms that had appeared in previous
perturbative calculations of P-wave decays are absorbed into a quantity that is
related to the amplitude for the heavy quark and antiquark to be in a relative
color-octet S-wave state. We predict all of the light-hadronic and
electromagnetic decays rates of the $\chi_c$ and $h_c$ states in terms of two
phenomenological parameters.


title: Relating Physical Observables in QCD without Scale-Scheme Ambiguity

abstract:
  We discuss the St\"uckelberg-Peterman extended renormalization group
equations in perturbative QCD, which express the invariance of physical
observables under renormalization-scale and scheme-parameter transformations.
We introduce a universal coupling function that covers all possible choices of
scale and scheme. Any perturbative series in QCD is shown to be equivalent to a
particular point in this function. This function can be computed from a set of
first-order differential equations involving the extended beta functions. We
propose the use of these evolution equations instead of perturbative series for
numerical evaluation of physical observables. This formalism is free of
scale-scheme ambiguity and allows a reliable error analysis of higher-order
corrections. It also provides a precise definition for $\Lambda_{\overline{\rm
MS}}$ as the pole in the associated 't Hooft scheme. A concrete application to
$R(e^+e^- \to {\rm hadrons})$ is presented.


title: Relativistic Constituent Quark Model for Baryons

abstract:
  The electroweak properties of nucleons and hyperons are calculated in a
relativistic constituent quark model. The baryons are treated as three quark
bound states, and the diagrams of perturbation theory are considered on the
light front. The electroweak properties of the baryons are of nonperturbative
nature and can be represented by one-loop diagrams. We consider different
extensions of the simplest model: quark form factors, configuration mixing of
the wave function, asymmetric wave function, wave function different from the
one of a harmonic oscillator valid up to energies of more than 30 GeV$^2$. A
comprehensive study of various baryonic properties is given: elastic form
factors of the nucleon, magnetic moments of the baryon octet, semileptonic weak
form factors. This analysis also gives the Kobayashi-Maskawa matrix element
$V_{us}$ and a sound symmetry breaking scheme for the Cabibbo theory. A
consistent physical picture appears in this work. The nucleon consists of an
unmixed, symmetric three quark state, the wave function of the hyperons is
however asymmetric with a spin-isospin-0 diquark. Only for the
strangeness-changing weak decay do we need nontrivial form factors.


title: Can $b\to s\gamma$ Close the Supersymmetric Higgs Production Window?

abstract:
  We show that the present limit from CLEO on the inclusive decay $b\to
s\gamma$ provides strong constraints on the parameters of the charged Higgs
sector in two-Higgs-Doublet-Models. Only a slight improvement in the
experimental bound will exclude the region in the Supersymmetric Higgs
parameter space which is inaccessible to collider searches.


title: Neutrino production through hadronic cascades in AGN accretion disks

abstract:
  We consider the production of neutrinos in active galactic nuclei (AGN)
through hadronic cascades. The initial, high energy nucleons are accelerated in
a source above the accretion disk around the central black hole. From the
source, the particles diffuse back to the disk and initiate hadronic cascades.
The observable output from the cascade are electromagnetic radiation and
neutrinos. We use the observed diffuse background X-ray luminosity, which
presumably results {}from this process, to predict the diffuse neutrino flux
close to existing limits from the Frejus experiment. The resulting neutrino
spectrum is $E^{-2}$ down to the $\GeV$ region. We discuss modifications of
this scenario which reduce the predicted neutrino flux.


title:
Detection of Intermediate Mass Higgs Bosons from Spontaneously Broken R
  Parity Supersymmetry

abstract:
  The Higgs sector in spontaneously broken R Parity supersymmetry (RPSUSY)
shows interesting features that require new search techniques. Both the mass
spectrum and production rates may differ from the standard model and minimal
supersymmetric model (MSSM) expectations. For some parameter choices, the
dominant Higgs boson decay mode can even be invisible, leading to events with
large missing transverse momentum carried by superweakly interacting majorons.
We study the reaction $pp \ra Z + H + X$, and find that it canlead to
detectable events at LHC/SSC for a large region of parameter space.


title: Vector mesons in the collective approach to SU(3)

abstract:
  We study the SU(3) extension of the Skyrme model with vector mesons in the
collective quantization scheme. The parameters of the model are fixed in its
mesonic sector. Fields which are excited by the collective rotation of the
classical soliton are determined by a variational method. The resulting
collective Hamiltonian which includes various symmetry breaking terms is
diagonalized exactly. This yields reasonable predictions for the mass
differences of the low-lying baryons. We furthermore investigate static
properties of these baryons in this model by evaluating all relevant matrix
elements using the exact eigenstates of the collective Hamiltonian.
Electromagnetic observables are found to approximately obey the predictions
obtained from SU(3) symmetry. Strong deviations from SU(3) symmetry are,
however, found for the matrix elements of strange vector and scalar operators
indicating a small amount of strangeness in the proton. The exploration of
axial currents shows that the results of the EMC experiment may be explained
with a small polarization of the strange sea of the proton without violating
the successful Cabibbo model for semileptonic hyperon decays.


title:
Implications of $b\rightarrow s\gamma $ decay measurements in testing
  the MSSM Higgs sector

abstract:
  The observation that the $b \rightarrow s\gamma $ decay rate is close to the
Standard Model value implies a large mass for the charged-Higgs boson in the
Minimum Supersymmetric Standard Model, that nearly closes the $t \rightarrow b
H^+$ decay channel. For $m_t = 150$ GeV, the parameter region $m_A \ltap 130$
GeV is excluded; this largely pre-empts LEP II searches and also partially
excludes a region that would be inaccessible to MSSM Higgs boson searches both
at LEP II and at SSC/LHC.


title:
Wilson Renormalization Group Analysis of Theories with Scalars and
  Fermions

abstract:
  The continuous block spin (Wilson) renormalization group equation governing
the scale dependence of the action is constructed for theories containing
scalars and fermions. A locally approximated form of this equation detailing
the structure of a generalized effective potential is numerically analyzed. The
role of the irrelevant operators in the nonperturbative renormalization group
running is elucidated and a comparison with the 1-loop perturbative results is
drawn. Focusing on the spontaneously broken phase of a model possessing a
discrete symmetry forbidding an explicit fermion mass term, mass bounds on both
the scalar and fermion degrees of freedom are established. The effect of the
generalized Yukawa coupling on the scalar mass upper bound is emphasized.


title:
Associated production of Intermediate Higgs or Z-boson with $t \bar t$
  pair in $\gamma \gamma$ collision

abstract:
  Photon-photon linear colliders can be realized by laser back-scattering
technique on the next generation linear $e^+e^-$ colliders. Here the associated
productions of an intermediate mass Higgs (IMH) or Z-boson with $t \bar t$ pair
in $\gamma\gamma$ collisions are studied. Since IMH is very unlikely to decay
into $t\bar t$ pair, $t\bar tH$ production is the only direct channel to probe
the Higgs-top Yukawa coupling in case of an IMH. $t\bar tZ$ production can be a
potential background to $t\bar tH$ if the Higgs mass is close to $m_Z$. As an
alternative to its parent $e^+e^-$ collider, $\gamma\gamma \to t\bar tH(Z)$
productions are compared with the corresponding productions in the $e^+e^-$
collisions.


title: Properties of Low-Lying Heavy-Light Mesons

abstract:
  We present preliminary results for the B meson decay constant and masses of
low-lying heavy-light mesons in the static limit. Calculations were performed
on the lattice in the quenched approximation using multistate smearing
functions generated from a Hamiltonian for a spinless relativistic quark. The
2S--1S and 1P--1S mass splittings are measured. Using the 1P--1S charmonium
splitting to set the overall scale, the ground state decay constant, f_B, is
319 +- 11 (stat) MeV.


title: About the realization of chiral symmetry in QCD2

abstract:
  Two dimensional massless Quantum Chromodynamics presents many features which
resemble those of the true theory. In particular the spectrum consists of
mesons and baryons arranged in flavor multiplets without parity doubling. We
analyze the implications of chiral symmetry, which is not spontaneously broken
in two dimensions, in the spectrum and in the quark condensate. We study how
parity doubling, an awaited consequence of Coleman's theorem, is avoided due to
the dimensionality of space-time and confinement. We prove that a chiral phase
transition is not possible in the theory.


title: Dynamical confinement in bosonized QCD2

abstract:
  In the bosonized version of two dimensional theories non trivial boundary
conditions (topology) play a crucial role. They are inevitable if one wants to
describe non singlet states. In abelian bosonization, color is the charge of a
topological current in terms of a non-linear meson field. We show that
confinement appears as the dynamical collapse of the topology associated with
its non trivial boundary conditions.


title:
Soft SUSY Breaking Terms in Stringy Scenarios: Computation and
  Phenomenological Viability

abstract:
  We calculate the soft SUSY breaking terms arising from a large class of
string scenarios, namely symmetric orbifold constructions, and study its
phenomenological viability. They exhibit a certain lack of universality, unlike
the usual assumptions of the minimal supersymmetric standard model. Assuming
gaugino condensation in the hidden sector as the source of SUSY breaking, it
turns out that squark and slepton masses tend to be much larger than gaugino
masses. Furthermore, we show that these soft breaking terms can be perfectly
consistent with both experimental and naturalness constraints (the latter comes
from the absence of fine tuning in the $SU(2)\times U(1)_Y\rightarrow
U(1)_{em}$ breaking process). This is certainly non--trivial and in fact
imposes interesting constraints on measurable quantities. More precisely, we
find that the gluino mass ($M_3$) and the chargino mass ($M_{\chi^{\pm}}$)
cannot be much higher than their present experimental lower bounds
($M_3\stackrel{<}{{}_\sim}285\ $GeV ; $M_{\chi^\pm}\stackrel{<}{{}_\sim}80\
$GeV), while squark and slepton masses must be much larger
($\stackrel{>}{{}_\sim} 1\ $TeV). This can be considered as an observational
signature of this kind of stringy scenarios. Besides, the top mass is
constrained to be within a range ($80\
$GeV$\stackrel{<}{{}_\sim}m_t\stackrel{<}{{}_\sim}165\ $GeV)


title:
Heavy Meson Hyperfine Splittings: A Puzzle for Heavy Quark Chiral
  Perturbation Theory

abstract:
  We show that there is a large discrepancy between the expected light flavor
dependence of the heavy pseudoscalar--vector mass splittings and the measured
values. We demonstrate that the one--loop calculation is unreliable. Moreover,
agreement with experiment requires the leading dependence on SU(3) symmetry
breaking to be nearly cancelled, so that the heavy quark mass dependence is
unknown and the expected dependence on the light quark mass is not realized.