title: FERMION MASSES IN EXTENDED TECHNICOLOUR

abstract:
  Talks presented at Beyond The Standard Model IV Conference, Lake Tahoe, Dec
94:
  NEW FERMION FAMILIES AND PRECISION ELECTROWEAK DATA: We highlight a trend in
the precision electroweak data towards light new physics and argue that some
spectra of strongly interacting technifamilies are plausibly compatible with
the data.
  FERMION MASSES IN EXTENDED TECHNICOLOUR: An ETC model with a minimal number
of operators responsible for fermion masses that break the global symmetries in
the observed manner postdicts the light quark masses. The up down mass
inversion may be explained by the inclusion of a family symmetric ansatz for
the CKM matrix angles.


title: An Estimate of the Proton Singlet Axial Constant

abstract:
  The value of the proton singlet axial constant is estimated. It has been
shown that the axial anomaly plays a crucial role in this calculation. Obtained
result is sufficiently suppressed in comparison with the naively expected one.
The magnitude of the strange quark contribution for the proton state is also
computed approximately.


title: QCD PREDICTIONS ON MULTIPARTICLE FINAL STATES

abstract:
  We compare QCD predictions with experimental data on inclusive multiparticle
observables whereby we discuss various realizations of the idea of parton
hadron duality which is related to a soft confinement mechanism. Special
emphasis is given on effects from the running $\alpha_s$, the soft gluon
interference, scaling properties and the role of the limiting scale $Q_0$ in
cascade evolution.


title: An analytic solution of the BFKL equation with momentum cutoffs

abstract:
  We outline a general method for obtaining the solution to the ($t=0$) BFKL
equation in the presence of transverse momentum cutoffs. A lower cutoff allows
one to avoid integration over nonperturbative momenta and an upper one is
needed from energy-momentum conservation. Our method allows for the inclusion
of an arbitrary number of poles in the kernel and is applicable to any input
distribution. Taking Mellin transforms, we discuss the effect of introducing
cutoffs by considering the singularity structure in the transform space. We
present an improved calculation of the small-$x$ slope of the gluon density.


title: Thermal fluctuations in electroweak phase transition

abstract:
  We estimate the amplitude of thermal fluctuations by calculating the typical
size of subcritical bubbles in cosmological electroweak phase transition and
show that this thermal fluctuation effect drastically changes dynamics of the
phase transition from the ordinary first order type with supercooling. From
this fact, we conclude that the standard electroweak baryogenesis scenario
associated with such a first order transition does not work in the minimal
standard model in certain conditions.


title: Nuclear Shadowing in the Structure Function $F_3(x)$

abstract:
  Nuclear modification of the structure function $F_3$ is investigated.
Although it could be estimated in the medium and large $x$ regions from the
nuclear structure function $F_2^A$, it is essentially unknown at small $x$. The
nuclear structure function $F_3^A$ at small $x$ is investigated in two
different theoretical models: a parton-recombination model with $Q^2$ rescaling
and an aligned-jet model. We find that these models predict completely
different behavior at small $x$: {\it antishadowing} in the first parton model
and {\it shadowing} in the aligned-jet model. Therefore, studies of the ratio
$F_3^A/F_3^D$ at small $x$ could be useful in discriminating among different
models, which produce similar shadowing behavior in the structure function
$F_2$. We also estimate currently acceptable nuclear modification of $F_3$ at
small $x$ by using $F_2^A/F_2^D$ experimental data and baryon-number
conservation.


title: The BFKL-Pomeron In Deep Inelastic Diffractive Dissociation near t=0

abstract:
  The small-$t$ behaviour of the deep inelastic diffractive dissociation cross
section in the triple Regge region is investigated, using the BFKL
approximation in perturbative QCD. We show that the cross section is finite at
$t=0$, but the diffusion in $\ln{k_t^2}$ leads to a large contribution of small
momenta at the triple Pomeron vertex. We study the dependence upon the total
energy and the invariant mass. At $t=0$, there is a decoupling of the three
BFKL singularities which is a consequence of the conservation of the conformal
dimension. For large invariant masses, the four gluon state in the upper
t-channel plays an important role and cannot be neglected.


title: Radiative Corrections to Charged Higgs Production in e+ e- Colliders

abstract:
  We study one loop electroweak corrections to the production of a pair of
charged Higgs bosons through an intermediate $Z$-boson or photon. In
particular, we consider the effects of graphs with top and bottom quarks and
squarks in the loop within the context of the Minimal Supersymmetric Model. We
find that the corrections can be considerable, and typically are of the order
of 10\% to 20\%.


title: The Pattern of Quark Masses and Maximal CP-Violation

abstract:
  A simple breaking of the subnuclear democracy of the quarks leads to a mixing
between the secons and the third family, in agreement with observation.
Introducing the mixing between the first and the second family, one finds an
interesting pattern of maximal CP-violation as well as complete determination
of the elements of the CKM matrix and of the unitarity triangle.


title:
The High-Temperature Two-Loop Effective Potential of the Electroweak
  Theory in a General 't Hooft Background Gauge

abstract:
  We calculate the high-temperature two-loop effective potential using a
general 't~Hooft background gauge. The dependence on the gauge-fixing parameter
$\xi$ is investigated. The effective coupling constant at the critical
temperature $g_3(T_c)^2$ is decreased considerably compared to the one-loop
result, independent of $\xi$.


title:
Two-Loop Analysis of Vector Current Propagators in Chiral Perturbation
  Theory

abstract:
  We perform a calculation of the isospin and hypercharge vector current
propagators ($\Delta_{V33}^{\mu\nu}(q^2)$ and $\Delta_{V88}^{\mu\nu}(q^2)$) to
two loops in chiral perturbation theory. The analysis is carried out with
straightforward Feynman diagram methods by making appropriate use of external
vector sources. Counterterms from the ${\cal O}(q^6)$ chiral lagrangian,
required to absorb divergences and scale dependence encountered at the two-loop
level, are constructed. Our final results are finite, covariant, and
scale-independent. Several applications are described, including a comparison
of the two-loop isospin vector spectral function with data and the construction
of new chiral sum rules.


title:
the Three-Point Vertex of Hadron Interaction with External Fields in QCD
  Sum Rules

abstract:
  The calculation method of the hadron interaction vertex with constant
external fields in QCD sum rules is discussed. The representation of the
polarization operator in terms of physical states contributions is considered
and the most suitable form of this representation is suggested. The estimates
of uncertainties in the previous calculations of hadron interaction vertices
with external fields are given.


title:
Non-Minimal Higgs Sectors: The Decoupling Limit and its Phenomenological
  Implications,

abstract:
  In models with a non-minimal Higgs sector, a decoupling limit can be defined.
In this limit, the masses of all the physical Higgs states are large (compared
to the scale of electroweak symmetry breaking) except for one neutral CP-even
Higgs scalar, whose properties are indistinguishable from the Higgs boson of
the minimal Standard Model. The decoupling limit of the most general
CP-conserving two-Higgs doublet model is formulated. Detection of evidence for
a non-minimal Higgs sector at future colliders in the decoupling limit may
present a formidable challenge for future Higgs searches.


title: STRANGELETS AT NON-ZERO TEMPERATURE

abstract:
  A description of strange quark matter at finite temperature is given, with
emphasis on the inclusion of finite size effects. For massless quarks all
thermodynamic quantities can be evaluated analytically, while the case of
massive quarks must be treated numerically. The resulting model is applied to
the phase equilibrium between strange hadronic matter and strangelets, and some
preliminary results are given.


title: Phenomenology of Superstrings

abstract:
  We consider the low energy phenomenology of superstrings. In particular we
analyse supersymmetry breaking via gaugino condensate and we compare the
phenomenology of the two different approaches to stabilize the dilaton field.
We study the cosmological constant problem and we show that it is possible to
have supersymmetry broken and zero cosmological constant. Finally, we discuss
the possibility of having an inflationary potential. Requiring that the
potential does not destabilize the dilaton field imposes an upper limit to the
density fluctuations which can be consistent with the COBE data.


title: Fermion Confinement by a Relativistic Flux Tube

abstract:
  We formulate the description of the dynamic confinement of a single fermion
by a flux tube. The range of applicability of this model extends from the
relativistic corrections of a slowly moving quark to the ultra-relativistic
motion in a heavy-light meson. The reduced Salpeter equation, also known as the
no-pair equation, provides the framework for our discussion. The Regge
structure is that of a Nambu string with one end fixed. Numerical solutions are
found giving very good fits to heavy-light meson masses. An Isgur-Wise function
with a zero recoil slope of $\xi'(1)\simeq -1.26 $ is obtained.


title: The Gluon Propagator in non-Abelian Weizs\"{a}cker-Williams fields

abstract:
  We carefully compute the gluon propagator in the background of a non--Abelian
Weizs\"{a}cker--Williams field. This background field is generated by the
valence quarks in very large nuclei. We find contact terms in the small
fluctuation equations of motion which induce corrections to a previously
incorrect result for the gluon propagator in such a background field. The well
known problem of the Hermiticity of certain operators in Light Cone gauge is
resolved for the Weizs\"{a}cker--Williams background field. This is achieved by
working in a gauge where singular terms in the equations of motion are absent
and then gauge transforming the small fluctuation fields to Light Cone gauge.


title:
Effects of Gravitational Smearing on Predictions of Supergravity Grand
  Unification

abstract:
  Limits on gravitational smearing from the dominant dimension 5 operator (with
strength characterised by $cM/2M_{Planck}$) are obtained using the LEP data in
supersymmetric SU(5) grand unification. Effects of c on the quasi infrared
fixed point solutio ns of $m_b/m_{\tau}$ unification are also analysed. It is
found that $c>0$ softens and $c<0$ stiffens the fixed point constraint. The
effect of c on the upper bound of the Higgs triplet mass is analysed and the
existence of a scaling induced by c is discussed. Tests for the existence of
gravitational smearing are discussed.


title: UNIVERSAL PROPERTIES OF ANGULAR CORRELATIONS IN QCD JETS

abstract:
  Predictions for angular correlations between an arbitrary number of partons
are derived in the high energy limit. The quantities considered depend on
angles and primary energy through a single variable $\epsilon$ which implies
certain scaling properties and relations between quite different observables.
These asymptotic predictions derived in the double log approximation of QCD are
checked against Monte Carlo calculations at the parton and hadron level.


title:
FIELD-THEORETIC TREATMENT OF MIXED NEUTRINOS IN A NEUTRINO AND MATTER
  BACKGROUND

abstract:
  We use the method of finite temperature field theory to examine the
propagation of mixed neutrinos through dense media, putting the emphasis in
those situations in which the neutrinos themselves are in the background. The
evolution equation for the flavor amplitudes is deduced, and the expressions
for the corresponding hamiltonian matrix are given explicitly. We find that, in
order to include the nonlinear effects due to the $\nu$-$\nu$ interactions, the
neutrino propagator that must be used in the calculation of the neutrino
self-energy diagrams that contain neutrinos in the internal lines is the
propagator for the neutrino modes in the medium instead of the thermal
free-field propagator. We also show how the absorptive contributions are
included in terms of a non-hermitian part of the hamiltonian matrix, which we
indicate how it is calculated. Our treatment provides a consistent
generalization of a method that has been successfully applied to the study of
neutrino oscillations in matter.


title: Beyond Standard Model: Report of Working Group II

abstract:
  Working group II at WHEPP3 concentrated on issues related to the
supersymmetric standard model as well as SUSY GUTS and neutrino properties. The
projects identified by various working groups as well as progress made in them
since WHEPP3 are briefly reviewed.


title: Jet Missing PT for Quark-Gluon Plasma Thermometry

abstract:
  At the LHC, where hard multi-jet events are common, large imbalances in the
total jet-\pt{} can arise due to the interaction of jets with the plasma formed
in heavy-ion collisions. We find that this missing-\pt{} spectrum yields a
measurement of the initial temperature of the plasma. Using commonly accepted
guesses for this temperature, and ISAJET estimates for jet cross sections, we
predict an order of thousand events at LHC with unbalanced $\pt>50$ GeV.


title: NONRELATIVISTIC MODEL FOR $b\OVERLINE{b}$ QUARKONIA

abstract:
  Experimental data for $b\bar{b}$ quarkonia have been compared with the
predictions of a variety of nonrelativistic quark models. It is found that a
potential $a\sqrt{r} - b/r +$ const gives good agreement, while many others do
not. Some implications of this observation are discussed.


title: Strangeness enhancement in heavy ion collisions

abstract:
  The enhancement of strange particle production observed in nucleus-nucleus
collisions at CERN is explained by the combined effect of the increase in the
relative number of strings containing strange constitutents at the ends, and
the final state interaction of co-moving secondaries~: $\pi + N \to K +
\Lambda/\Sigma$.


title: QCD sum rules with finite masses

abstract:
  The concept of QCD sum rules is extended to bound states composed of
particles with finite mass such as scalar quarks or strange quarks. It turns
out that mass corrections become important in this context. The number of
relevant corrections is analyzed in a systematic discussion of the IR- and
UV-divergencies, leading in general to a finite number of corrections. The
results are demonstrated for a system of two massless quarks and two heavy
scalar quarks.


title:
$\rho\omega$--Mixing and the Pion Electromagnetic Form Factor in the
  Nambu--Jona-Lasinio Model

abstract:
  The $\rho\omega$--mixing generated by the isospin breaking of the current
quark masses $m_{u} \neq m_{d}$ is studied within the bosonized NJL model in
the gradient expansion. The resulting effective meson lagrangian naturally
incorperates vector meson dominance. By including pion loops an excellent
description of both the pion electromagnetic form factor and of the
$\pi^+\pi^-$ phase shifts in the vector--isovector channel is obtained. The
$\rho\omega$--mixing can be treated in the static approximation but is
absolutely necessary to reproduce the fine structure of the electromagnetic
form factor, while the pion loops are necessary to obtain the correct energy
dependence of the phase shifts.


title: Violations of lepton flavour and CP in supersymmetric unified theories

abstract:
  As a consequence of the large top quark Yukawa coupling, supersymmetric
unified theories with soft supersymmetry breaking terms generated at the Planck
scale predict lepton flavour and CP violating processes with significant rates.
The flavour violating parameters of the low energy theory are derived in both
SU(5) and SO(10) theories, and are used to calculate the rate for mu --> e
gamma. The sensitivity of the search for mu --> e gamma is compared with that
for mu --> e conversion in atoms, tau --> mu gamma and the electric dipole
moment of the electron. The experimental search for these processes is shown to
provide a very significant test of supersymmetric unification, especially in
SO(10) but also in SU(5).


title: Gluon Mass from Instantons

abstract:
  The gluon propagator is calculated in the instanton background in a form
appropriate for extracting the momentum dependent gluon mass. In
background-$\xi$-gauge we get for the mass $400$MeV for small $p^2$ independent
of the gauge parameter $\xi$.


title:
Could the Supersymmetric Higgs Particles Naturally be Pseudo-Goldstone
  Bosons?

abstract:
  The doublet-triplet splitting problem is perhaps the most problematic aspect
of supersymmetric grand unified theories. It can be argued that the most
natural reason for the Higgs doublets to be light is that they are
pseudo-Goldstone bosons associated with the spontaneous breakdown of an
accidental global symmetry. In this paper we discuss the possibility of
implementing this idea in the SU(6) model of refs. \cite{Zur,Bar2,Bar3,Bar4}.
We show that although it is simple to generate an accidental symmetry of the
renormalizable terms of the potential, it is quite difficult to construct a
model which allows for the preservation of the accidental symmetry in the
nonrenormalizable terms. We summarize the constraints on such models and then
give three different ways to construct a superpotential where the dangerous
mixing terms are sufficiently suppressed even in the presence of
nonrenormalizable operators. With these examples we demonstrate the existence
of consistent models implementing the Higgs as pseudo-Goldstone boson scheme.
We extend one of the three examples to include fermion masses. We also show
that when restricted to regular group embeddings the only possible models
without light triplets are trivial generalizations of the SU(6) model we
consider.


title: Probing the Standard Model with hadronic WZ Production

abstract:
  The cross section for producing $WZ$ pairs at hadron colliders is calculated
to order $\alpha_s$ for general $C$ and $P$ conserving $WWZ$ couplings. The
effects of the next-to-leading-order corrections on the derived sensitivity
limits for anomalous $WWZ$ couplings are discussed. The prospects for observing
the approximate amplitude zero, which is present in the standard model $WZ$
helicity amplitudes, are also discussed.


title:
The $l=1$ Hyperfine Splitting in Bottomium as a Precise Probe of the QCD
  Vacuum.

abstract:
  By relating fine and hyperfine spittings for l=1 states in bottomium we can
factor out the less tractable part of the perturbative and nonperturbative
effects. Reliable predictions for one of the fine splittings and the hyperfine
splitting can then be made calculating in terms of the remaining fine
splitting, which is then taken from experiment; perturbative and
nonperturbative corrections to these relations are under full control. The
method (which produces reasonable results even for the $c{\bar c}$ system)
predicts a value of 1.5 MeV for the $(s=1)-(s=0)$ splitting in $b{\bar b}$,
opposite in sign to that in $c{\bar c}$. For this result the contribution of
the gluon condensate $<\alpha_s G^2>$ is essential, as any model (in particular
potential models) which neglects this would give a negative $b{\bar b}$
hyperfine splitting.


title:
Using Decay Angle Correlations to Detect CP Violation in the Neutral
  Higgs Sector

abstract:
  We demonstrate that decay angle correlations in $\taum\taup$ and $t\anti t$
decay modes could allow a determination of whether or not a neutral Higgs boson
is a CP eigenstate. Sensitivity of the correlations is illustrated in the case
of the $\epem\rta Z \hn$ and $\mupmum\rta \hn$ production processes for a
two-doublet Higgs model with CP-violating neutral sector. A very useful
technique for minimizing `depolarization-factor' suppressions of the
correlations in the $t\anti t$ mode is introduced.


title:
Adiabatic Analysis of Gravitationally-Induced Three-Flavor Neutrino
  Oscillations

abstract:
  Some implications of the proposal that flavor nondiagonal couplings of
neutrinos to gravity might resolve the solar neutrino problem are considered in
the context of three neutrino flavours. Using an adiabatic approximation
iso-SNU curves are calculated for the neutrinos which most likely contribute to
the observed solar neutrino deficiency. We show that results obtained with
two-flavor models can be recovered, and discuss the effects of the addition of
a third flavor. Some results are obtained for this case, and these values are
compared with recent experimental data.


title: CPT, Strings, and Meson Factories

abstract:
  Spontaneous breaking of CPT is possible in string theory. We show that it can
arise at a level within reach of experiments at meson factories currently being
built or designed. For $\phi$, $B$, and $\tau$-charm factories, we discuss the
likely experimental string signatures and provide estimates of the bounds that
might be attained in these machines.


title: A Spectator-Quark-Model for the Photoproduction of Kaons

abstract:
  A simple model for the photoproduction of kaons off protons with a lambda
hyperon in the final state is presented. In a quark model, the interaction is
modelled by the pair-creation of the (anti-) strange quarks in the final state
which recombine with the three quarks of the proton to form the lambda and
kaon. The calculated scattering cross sections for photon energies up to
$E_\gamma = 1.9 \; \mbox{GeV}$ are compared to experiment. The pair-creation
process is found to have a significant contribution to the total cross section.


title: From the Standard Model to Dark Matter

abstract:
  The standard model of particle physics is marvelously successful. However, it
is obviously not a complete or final theory. I shall argue here that the
structure of the standard model gives some quite concrete, compelling hints
regarding what lies beyond. Taking these hints seriously, one is led to predict
the existence of new types of very weakly interacting matter, stable on
cosmological time scales and produced with cosmologically interesting
densities--that is, ``dark matter''.


title: QCD Running Coupling Constant in the Timelike Region

abstract:
  By using a non-perturbative expansion and the dispersion relation for the
Adler $D$--function we propose a new method for constructing the QCD effective
coupling constant in the timelike region.


title: Intermittency and Bose-Einstein correlations

abstract:
  The role of Bose-Einstein correlations in a widely discussed intermittency
phenomenon is reviewed. In particular, it is shown that particle correlations
of different origin are better displayed when analysed as functions of
appropriately chosen variables. Correspondingly, if the shape of Bose-Einstein
contribution is chosen to be Gaussian in 3-momentum transferred, it provides
the power-like law in 4-momentum squared and is smeared out in
(pseudo)rapidity.


title: The energy behaviour of real and virtual photon--proton cross sections

abstract:
  The recent F$_2$ measurements at HERA are discussed in the framework of
virtual photon--proton cross section. The energy behaviour of the cross section
is studied for different $Q^2$ values, ranging from 0 to 1000 GeV$^2$ for
center of mass energies $1.75 < W < 300$ GeV.


title: $D^0 - \bar D^0$ Mixing in the Presence of Isosinglet Quarks

abstract:
  We analyse $\Delta C=2$ transitions in the framework of a minimal extension
of the Standard Model where either a $Q=2/3$ or a $Q=-1/3$ isosinglet quark is
added to the standard quark spectrum. In the case of a $Q=2/3$ isosinglet
quark, it is shown that there is a significant region of parameter space where
$D^0 - \bar D^0$ mixing is sufficiently enhanced to be observed at the next
round of experiments. On the contrary, in the case of a $Q=-1/3$ isosinglet
quark, it is pointed out that obtaining a substancial enhancement of $D^0 -
\bar D^0$ mixing, while complying with the experimental constraints on rare
kaon decays, requires a contrived choice of parameters.


title: On The Effect of Binding in Deep Inelastic Scattering

abstract:
  The phenomenon of scaling in deep inelastic lepton-nucleon scattering is
usually explained in terms of the Feynman parton model, and the logarithmic
corrections to scaling are explained in the framework of perturbative QCD. For
testing the validity of the parton model, we consider the deep inelastic
electron scattering in a model in which the system electromagnetic current
operator explicitly satisfies relativistic invariance and current conservation.
Let the struck particle have the fraction $\xi$ of the total momentum in the
infinite momentum frame. Then it is shown that, due to binding of particles in
the system under consideration, the Bjorken variable $x$ no longer can be
interpreted as $\xi$, even in the Bjorken limit and in zero order of the
perturbation theory. We argue that, as a result, the data on deep inelastic
scattering alone do not make it possible to determine the $\xi$ distribution of
quarks in the nucleon.


title: Introduction to Theories of Fermion Masses

abstract:
  This paper is based on four lectures given at the Trieste Summer School 1994
on theories of fermion masses. The first two lectures introduce three
mechanisms which have been used to construct models of fermion masses. We then
discuss some recent applications of these ideas. In the last lecture we briefly
review SO(10) and some predictive theories of fermion masses.


title:
Quark off-shell contributions to $K_{L}\to\gamma\gamma$ in a bound-state
  approach

abstract:
  We present a new piece of evidence in favour of the importance of the quark
off-shellness in the kaon. The matrix elements of the flavour-changing
operators for $K_{L}\to\gamma\gamma$ comply with the general behaviour of the
matrix elements expected in the pairing bound-state model used here. The
present calculation in essence agrees with previous chiral-quark results. The
off-shell contribution turns out to be dominant (the model on-shell amplitude
being at the 10% level). Compared with the chiral perturbation-theory approach,
our off-shell contribution is an entirely new ${\cal{O}}(p^{4})$ {\em
direct-decay} piece, whereas the non-diagonal magnetic-moment term belongs to
the order ${\cal{O}}(p^{6})$.


title:
Effective Mass Matrix for Light Neutrinos Consistent with Solar and
  Atmospheric Neutrino Experiments

abstract:
  We propose an effective mass matrix for light neutrinos which is consistent
with the mixing pattern indicated by solar and atmospheric neutrino
experiments. Two scenarios for the mass eigenvalues are discussed and the
connection with double beta decay is noted.


title: QUARK OFF-SHELL EFFECTS IN FLAVOUR-CHANGING DECAYS

abstract:
  We discuss some flavour-changing effective Lagrangians, obtained from scales
above 1 GeV, which vanish on the quark mass shell. Although the effects of such
effective Lagrangians are zero in the limit of vanishing bound-state
interactions, we have shown that they have a significant impact on the
processes $K\rightarrow\gamma\gamma$ and $B_s \rightarrow\gamma\gamma$.


title: Fermion Masses and SO(10) SUSY GUTs

abstract:
  In this talk I summarize published work on a systematic operator analysis for
fermion masses in a class of effective supersymmetric SO(10)
GUTs\cite{adhrs}~\footnote{This work is in collaboration with G. Anderson, S.
Dimopoulos, L.J. Hall, and G. Starkman.}. Given a minimal set of four operators
at $M_G$, we have just 6 parameters in the fermion mass matrices. We thus make
8 predictions for the 14 low energy observables (9 quark and charged lepton
masses, 4 quark mixing angles and $\tan \beta$). Several models, i.e.
particular sets of dominant operators, are in quantitative agreement with the
low energy data. In the second half of the talk I discuss the necessary
ingredients for an SO(10) GUT valid below the Planck (or string) scale which
reproduces one of our models. \footnote{These are preliminary results of work
in progress with Lawrence Hall.} This complete GUT should still be interpreted
as an effective field theory, i.e. perhaps the low energy limit of a string
theory.


title: Current Issues in Perturbative QCD

abstract:
  Invited talk presented at the 1994 Meeting of The Division of Particles and
Fields of the American Physical Society, Albuquerque NM, August 1-6, 1994


title: Non-trivial Tests of EW Corrections via $alpha$, $G_F$ and $M_{W,Z}$

abstract:
  The standard electroweak theory is tested at non-trivial quantum correction
level through $\alpha$, $G_F$ and the latest data of the weak-boson masses. The
improved-Born approximation and the non-decoupling top-quark effects are
studied without depending on the CDF data of $m_t$, while the bosonic effects
are examined by fully taking account of it.


title: Energy levels of the soliton--heavy-meson bound states

abstract:
  We investigate the bound states of heavy mesons with finite masses to a
classical soliton solution in the Skyrme model. For a given model Lagrangian we
solve the equations of motion exactly so that the heavy vector mesons are
treated on the same footing as the heavy pseudoscalar mesons. All the energy
levels of higher grand spin states as well as the ground state are given over a
wide range of the heavy meson masses. We also examine the validity of the
approximations used in the literatures. The recoil effect of finite mass
soliton is naively estimated.


title: Chiral perturbation theory

abstract:
  The main elements and methods of chiral perturbation theory, the effective
field theory of the Standard Model below the scale of spontaneous chiral
symmetry breaking, are summarized. Applications to the interactions of mesons
and baryons at low energies are reviewed, with special emphasis on developments
of the last three years. Among the topics covered are the strong,
electromagnetic and semileptonic weak interactions of mesons at and beyond
next--to--leading order in the chiral expansion, nonleptonic weak interactions
of mesons, virtual photon corrections and the meson--baryon system. The
discussion is limited to processes at zero temperature, for infinite volume and
with at most one baryon.


title: Final state interaction in the production of heavy unstable particles

abstract:
  We make an attempt to discuss in detail the effects originating from the
final state interaction in the processes involving production of unstable
elementary particles and their subsequent decay. Two complementary scenarios
are considered: the single resonance production and the production of two
resonances. We argue that part of the corrections due to the final state
interaction can be connected with the Coulomb phases of the involved charge
particles; the presence of the unstable particle in the problem makes the
Coulomb phase ``visible''. It is shown how corrections due to the final state
interaction disappear when one proceeds to the total cross-sections. We derive
one-loop non-factorizable radiative corrections to the lowest order matrix
element of both single and double resonance production. We discuss how the
infrared limit of the theories with the unstable particles is modified. In
conclusion we briefly discuss our results in the context of the forthcoming
experiments on the $W^+W^-$ and the $t\bar t$ production at LEP $2$ and NLC.


title: QUARK MATTER STRUCTURE IN NEUTRON STARS

abstract:
  For physically reasonable bulk and surface properties, quark matter has
recently been found to coexist with nuclear matter inside neutron stars in a
uniform background of electrons. The microstructure of this mixed phase starts
out with a few quark matter droplets embedded in the nuclear matter but as the
density of droplets increase towards the center of the neutron star they merge
into rods, plates and other structures. The topology, size as well as Coulomb
and surface energies of these structures depend sensitively on the
quark/nuclear matter interface tension. A major fraction of the interior of
neutron stars could consist of matter in this new phase, which would provide
new mechanisms for glitches, cooling and supernovae.


title: SU(2) HEAVY FLAVOUR SYMMETRY FOR B -> K(K^*) HADRONIC FORM FACTORS

abstract:
  We show that the factorization assumption in colour-suppressed $B$ meson
decays is not ruled out by experimental data on $B \ra K(K^*) +
J/\Psi(\Psi^{'})$. The problem previously pointed out might be due to an
inadequate choice of hadronic form factors. Within the Isgur-Wise SU(2) heavy
flavour symmetry framework, we search for possible $q^2$-dependences of form
factors that satisfy both the large longitudinal polarization $\rho_L$ observed
in $B \ra K^* + J/\Psi$ and the relatively small ratio of rates $R_{J/\Psi} =
\Gamma(B \ra K^* + J/\Psi)/\Gamma(B \ra K + J/\Psi)$. We find out that the
puzzle could be essentially understood if the $A_1(q^2)$ form factor is frankly
decreasing (instead of being almost constant or increasing as commonly
assumed). Of course, the possibility of understanding experimental data is not
necessarily a proof of factorization.


title: String Consistency for Unified Model Building

abstract:
  We explore the use of real fermionization as a test case for understanding
how specific features of phenomenological interest in the low-energy effective
superpotential are realized in exact solutions to heterotic superstring theory.
We present pedagogic examples of models which realize SO(10) as a level two
current algebra on the world-sheet, and discuss in general how higher level
current algebras can be realized in the tensor product of simple constituent
conformal field theories. We describe formal developments necessary to compute
couplings in models built using real fermionization. This allows us to isolate
cases of spin structures where the standard prescription for real
fermionization may break down.


title:
Residual heavy quark and boson interactions: the role of the $Zb\bar b$
  vertex

abstract:
  We establish the most general parametrization of the new physics tested by
present precision measurements and possibly responsible for any deviation of
the $Z\to b \bar b $ amplitude from its Standard Model result, under the
assumption that it is CP symmetric and is induced by degrees of freedom which
are too heavy to be ~directly produced at the future Colliders. This is
achieved by writing the complete list of the $SU(3)_c\times SU(2) \times U(1) $
gauge invariant and CP symmetric $dim=6$ operators, involving only quarks of
the third family and/or bosons. The quark ~containing operators are divided
into two classes, according to whether they involve the $t_R$ field or not.
Each class contains 14 quark operators. We then proceed to derive the
constraints from present precision measurements, on the first class of the 14
$t_R$ involving operators. We show that the $Zb \bar b$ vertex plays a
fundamental role to discriminate not only between these operators, but also
between this whole scheme and an alternative one like \eg\@ an MSSM description
with light chargino and neutral Higgs.


title: Self-energy of Heavy Quark

abstract:
  We demonstrate that to calculate the self-energy of a heavy quark in the
heavy quark limit (or the heavy fermion limit in what is called the Baryon
Chiral Perturbation Theory), the use of standard dimensional regularization
provides only the quantum limit: opposite to the heavy quark (or classical)
limit that one wishes to obtain. We thus devised a standard
ultraviolet/infrared regularization procedure in calculating the one- and
two-loop contributions to the heavy quark self-energy in this limit. Then the
one-loop result is shown to provide the standard classical Coulomb self-energy
of a static colour source that is linearly proportional to the untraviolet
cutoff $\Lambda$. All the two-loop contributions are found to be proportional
to $\Lambda \ln(\Lambda/\lambda)$ where $\lambda$ is the infrared cutoff. Often
only the contribution from the bubble (light quarks, gluon and ghost) insertion
to the gluon propagator has been considered as the $O(\alpha_s)$ correction to
the Coulomb energy to this order. Our result shows that other contributions are
of the same magnitude, thus have to be taken into account.


title:
Properties of vector mesons at finite temperature -effective lagrangian
  approach-

abstract:
  The properties of $\rho$-mesons at finite temperature ($T$) are examined with
an effective chiral lagrangian in which vector and axial-vector mesons are
included as massive Yang-Mills fields of the chiral symmetry. It is shown that,
at $T^2$ order, the effective mass is not changed but only the mixing effect in
vector and axial-vector correlator appears.


title: Gamma Rays from Neutralino Annihilation

abstract:
  We calculate the flux of cosmic gamma rays expected {}from the annihilation
of neutralinos in the Galactic halo. Our calculation of the annihilation cross
section to two photons improves the existing calculations by inclusion of exact
one-loop diagrams for the amplitudes involving Higgs boson and chargino states
as well as those involving fermion and sfermion states. A survey of
supersymmetric parameter space shows that numerous models would be observable
at the $3\sigma$ level with an air Cerenkov telescope with an exposure of $10^4
\meter^2 \yr$.


title: Disoriented Chiral Condensate

abstract:
  The current theoretical understanding of disoriented chiral condensate is
briefly reviewed. I discuss the basic idea, the formation mechanism and
experimental signatures of DCC in high energy collisions.


title:
Analysis of the spin structure function $g_2(x,Q^2)$ and twist-3
  operators

abstract:
  We discuss the spin-dependent structure function $g_2(x,Q^2)$ in the
framework of the operator product expansion. It is noted that the anomalous
dimensions and coefficient functions for the twist-3 gluon-field-dependent
operators depend on the choice of the operator basis. The role played by the
operators proportional to the equation of motion is clarified.


title:
Target Mass Corrections to QCD Bjorken Sum Rule for Nucleon Spin
  Structure Functions

abstract:
  We discuss the possible target mass corrections in the QCD analysis of
nucleon's spin-dependent structure functions measured in the polarized
deep-inelastic leptoproduction. The target mass correction for the QCD Bjorken
sum rule is obtained from the Nachtmann moment and its magnitude is estimated
employing positivity bound as well as the experimental data for the asymmetry
parameters. We also study the uncertainty due to target mass effects in
determining the QCD effective coupling constant $\alpha_s(Q^2)$ from the
Bjorken sum rule. The target mass effect for the Ellis-Jaffe sum rule is also
briefly discussed.


title: The theory and phenomenology of polarized deep inelastic scattering

abstract:
  Comprehensive review paper on the theory and phenomenology of polarized deep
inelastic scattering, to appear in Physics Reports


title: A Higgs-Free Model for Fundamental Interactions and its Implications

abstract:
  A model for strong, electroweak and gravitational interactions based on the
local symmetry group $G=SU(3)\times SU(2)_{L}\times U(1)\times C$ where $C$ is
the local conformal symmetry group is proposed. The natural minimal
$G$-invariant form of total lagrangian is postulated. It contains all Standard
Model fields and the gravitational interaction, however the Higgs mass term
$\mu^2\Phi^{\dagger}\Phi$ is forbidden. Using the unitary gauge and the
conformal scale fixing conditions we can eliminate all four real components of
the Higgs field in this model. In spite of that the tree level masses of vector
mesons, leptons and quarks are automatically generated and are given by the
same formulas as in the conventional Standard Model. In this manner one gets
the mass generation without the mechanism of spontaneous symmetry breaking. We
calculated in this model the predictions for a series of electroweak
observables such as $m_{W_{\pm}}/m_Z$, $sin^2\theta_W^{eff}$, Z-boson widths,
$A^l_{FB}$, etc, and we show that they are in agreement with experimental data.
The gravitational sector of the model is also analyzed and it is shown that the
model admits in the classical limit the Einsteinian form of gravitational
interactions.


title: On the Value of R=\Gamma_h/\Gamma_l at LEP

abstract:
  We show that the present experimental LEP average R=\Gamma_h/\Gamma_l= 20.795
+- 0.040 is not unambiguous due to the presence of substantial systematic
effects which cannot be interpreted within gaussian statistics. We find by
Montecarlo simulation that the C.L. of the original LEP sample is only 3.8
\cdot 10^{-4}. We suggest that a reliable extimate of the true R-value is
20.60< R < 20.98 which produces only a very poor determination of the strong
coupling constant at the Z mass scale, 0.10< \alpha_s(M_z)< 0.15.


title: Tests of Direct and Indirect CPT Violation at a B Factory

abstract:
  The issue of testing CPT invariance at a $B$ factory is considered. We
present asymmetries that permit a clean extraction of quantities parametrizing
direct and indirect CPT violation, using information from $\Upsilon(4S)$ decay
via coherent $B_d\overline{B_d}$ pairs into various final states. Estimates are
given of the bounds on CPT violation that could be obtained in present and
planned machines.


title: Heavy flavor contributions to the Drell-Yan cross section

abstract:
  We investigate the effect of heavy flavor contributions to vector boson ($V$
= $\gamma$, $Z$, $W$) production which is described by the Drell-Yan mechanism.
All reactions with bottom and top quarks ($Q_i$ = $b$, $t$) in the final state,
like $q_1 + \bar{q}_2\rightarrow V + Q_1 + \bar{Q}_2$ and $g + g\rightarrow V +
Q_1 + \bar{Q}_2$, are considered. This study also includes the virtual
contributions containing heavy flavor loops which were not taken into account
earlier in the literature. Our analysis reveals that the above corrections to
the Drell-Yan cross section are very small. Only at energies characteristic for
the LHC they are of the same order of magnitude as the order \alphastwo~QCD
contributions due to light quark and gluon subprocesses calculated earlier in
the literature.


title: Quark Matter Droplet Formation in Neutron Stars

abstract:
  The formation rate of quark matter droplets in neutron stars is calculated
from a combination of bubble formation rates in cold degenerate and high
temperature matter. Nuclear matter calculations of the viscosity and thermal
conductivity are applied. Results show that droplets form only in the core of
neutron stars shortly after supernova collapse, where pressures and
temperatures are high, and for sufficiently small interface tension between
nuclear and quark matter. Coulomb energies hinder formation of large droplets
whereas the presence of strange hadrons in nuclear matter increase the droplet
formation rate.


title: Effective Field Theory Approach to High-Temperature Thermodynamics

abstract:
  An effective field theory approach is developed for calculating the
thermodynamic properties of a field theory at high temperature $T$ and weak
coupling $g$. The effective theory is the 3-dimensional field theory obtained
by dimensional reduction to the bosonic zero-frequency modes. The parameters of
the effective theory can be calculated as perturbation series in the running
coupling constant $g^2(T)$. The free energy is separated into the contributions
from the momentum scales $T$ and $gT$, respectively. The first term can be
written as a perturbation series in $g^2(T)$. If all forces are screened at the
scale $gT$, the second term can be calculated as a perturbation series in
$g(T)$ beginning at order $g^3$. The parameters of the effective theory satisfy
renormalization group equations that can be used to sum up leading logarithms
of $T/(gT)$. We apply this method to a massless scalar field with a $\Phi^4$
interaction, calculating the free energy to order $g^6 \log g$ and the
screening mass to order $g^5 \log g$.


title: Diffractive Vector Meson Production at Large Momentum Transfer

abstract:
  The diffractive process $\gamma p\to V + X$ (where $V$ is a vector meson and
$X$ results from the dissociation of the proton) is studied. In particular, we
consider the region of large momentum transfer (i.e. $|t|\gg\Lambda_{QCD}^2$)
and large centre-of-mass (CM) energy, $s$. The asymptotic $(s \to \infty,
s/|t|\gg 1$) behaviour is derived from the BFKL equation and compared to that
which is obtained in the Born approximation (two-gluon exchange). We also
calculate the corrections to the Born graphs by iterating the BFKL kernel
numerically. Improved convergence of the BFKL series is found by summing the
logarithms which occur when an exchanged gluon goes nearly on shell.
Importantly, we find evidence that the asymptotic solution to the BFKL equation
is inappropriate over most of the HERA range and we provide more realistic
predictions for the cross section. The predicted cross section is not too small
and can be measured at HERA, up to momentum transfers $|t| \sim 10$GeV$^2$.


title: Associated Slepton-Neutralino/Chargino Production at LEPxLHC

abstract:
  We examine for representative gaugino-higgsino mixing scenarios
slepton-neutralino and slepton-chargino production in deep inelastic
ep-scattering at $\sqrt{s}=1.8$ TeV. We find sneutrino-chargino production to
be the dominant process with cross sections more than one order of magnitude
bigger than those for slepton-squark production. Also for associated production
of sneutrinos and zino-like neutralinos the cross sections are at least
comparable to those for $\tilde l \tilde q$-production, whereas
selectron-neutralino/chargino production is with cross sections significantly
smaller than those for selectron-squark production less favorable. Typical
signatures include events with up to four charged leptons, hadronic jets and,
in some cases, gauge bosons.


title:
Complete Weak-Scale Threshold Corrections in the Minimal Supersymmetric
  Standard Model

abstract:
  We compute the full set of weak-scale gauge and Yukawa threshold corrections
in the minimal supersymmetric standard model, and use them to study the effects
of the supersymmetric particle spectrum on gauge and Yukawa coupling
unification.


title:
Probing Strongly-interacting Electroweak Dynamics through $W^+W^-/ZZ$
  Ratios at Future $e^+e^-$ Colliders

abstract:
  We point out that the ratio of $W^+ W^- \to W^+ W^-$ and $W^+W^- \to ZZ$
cross sections is a sensitive probe of the dynamics of electroweak symmetry
breaking, in the CM energy region $\sqrt {s_{\rm ww}^{}} \agt 1$~TeV where
vector boson scattering may well become strong. We suggest ways in which this
ratio can be extracted at a 1.5 TeV $e^+e^-$ linear collider, using $W^\pm,Z
\to jj$ hadronic decays and relying on dijet mass resolution to provide
statistical discrimination between $W^\pm$ and $Z$. $WW$ fusion processes
studied here are unique for exploring scalar resonances of mass about 1 TeV and
are complementary to studies via the direct channel $e^+ e^- \rightarrow
W^+W^-$ for the vector and non-resonant cases. With an integrated luminosity of
200 fb$^{-1}$, the signals obtained are statistically significant. Comparison
with a study of $e^-e^- \rightarrow \nu\nu W^-W^-$ process is made.
Enhancements of the signal rate from using a polarized electron beam, or at a 2
TeV $e^+e^-$ linear collider and possible higher energy $\mu^+\mu^-$ colliders,
are also presented.


title: Domain Walls in a FRW Universe

abstract:
  We solve the equations of motion for a scalar field with domain wall boundary
conditions in a Friedmann-Robertson-Walker (FRW) spacetime. We find (in
agreement with Basu and Vilenkin) that no domain wall solutions exist in de
Sitter spacetime for h = H/m >= 1/2, where H is the Hubble parameter and m is
the scalar mass. In the general FRW case we develop a systematic perturbative
expansion in h to arrive at an approximate solution to the field equations. We
calculate the energy momentum tensor of the domain wall configuration, and show
that the energy density can become negative at the core of the defect for some
values of the non-minimal coupling parameter xi. We develop a translationally
invariant theory for fluctuations of the wall, obtain the effective Lagrangian
for these fluctuations, and quantize them using the Bunch-Davies vacuum in the
de Sitter case. Unlike previous analyses, we find that the fluctuations act as
zero-mass (as opposed to tachyonic) modes. This allows us to calculate the
distortion and the normal-normal correlators for the surface. The normal-normal
correlator decreases logarithmically with the distance between points for large
times and distances, indicating that the interface becomes rougher than in
Minkowski spacetime.


title: PERTURBATIVE QCD AND NUCLEON STRUCTURE FUNCTIONS.

abstract:
  We review the basic aspects of the perturbative QCD based on the operator
product expansion to analyze the nucleon structure functions in a pedagogical
way. We explain the non-trivial relation between the QCD results and the parton
model especially to understand the polarized nucleon structure functions which
deserve much attentions in recent years.


title:
Soft-breaking correction to hard supersymmetric relations: QCD
  correction to squark decay

abstract:
  Supersymmetric relations between dimensionless couplings receive finite
correction at one-loop when supersymmetry is broken softly. We calculate the
$O(\alpha_s)$ correction to the squark decay width to a quark and an
electroweak gaugino, which is found to be nonvanishing. Logarithmic correction
appears when the gluino is heavy.


title: NJL model with vector couplings vs. phenomenology

abstract:
  We study the pseudoscalar, vector and axial current correlation functions in
SU(2)-NJL model with scalar and vector couplings. The correlation functions are
evaluated in leading order in number of colors $N_c$. As it is expected in the
pseudoscalar channel pions appear as Goldstone bosons, and after fixing the
cutoff to reproduce the physical pion decay constant, we obtain well-known
current-algebra results. For the vector and axial channels we use essentially
that at spacelike momenta the correlation functions can be related to the
experimentally known spectral density via dispersion relations. We show that
the latter imposes strong bounds on the strength of the vector coupling in the
model. We find that the commonly used on-shell treatment of the vector and
axial mesons (identified as poles at large timelike momenta) fails to reproduce
the behavior of the corresponding correlation functions at small spacelike
momenta extracted from the physical spectral density. The parameters of the NJL
model fixed by the correlation functions at small spacelike momenta differ
noticeably from those of the on-shell treatment.


title: Chiral Dynamics in Nucleons and Nuclei

abstract:
  We review the implications of the spontaneous chiral symmetry breaking in QCD
for processes involving one, two or more nucleons.


title: Strong BBP couplings for the charmed baryons

abstract:
  According to the Coleman-Glashow null theorem if all the symmetry breaking
effects belong to the same regular representation (octet in the case of SU(3)
and {\bf 15} in the case of SU(4)) and are generated in a tadpole type
mechanism, the strangeness changing (charm changing) weak transitions generated
through the S$_{6}$ (S$_{9}$) tadpole must vanish. Exploiting this null result,
we find relations between the BBP coupling constants which allow us to write
the coupling constants in terms of two parameters and baryon masses. Fixing
these two parameters ( $g_{NN\pi}$ and $g_{\Lambda \Sigma \pi}$) from
experiments, we estimate the remaining coupling constants.


title: Vacuum Contributions in a Chiral Effective Lagrangian for Nuclei

abstract:
  A relativistic hadronic model for nuclear matter and finite nuclei, which
incorporates nonlinear chiral symmetry and broken scale invariance, is
presented and applied at the one-baryon-loop level to finite nuclei. The model
contains an effective light scalar field that is responsible for the mid-range
nucleon--nucleon attraction and which has anomalous scaling behavior. One-loop
vacuum contributions in this background scalar field at finite density are
constrained by low-energy theorems that reflect the broken scale invariance of
quantum chromodynamics. A mean-field energy functional for nuclear matter and
nuclei is derived that contains small powers of the fields and their
derivatives, and the validity of this truncation is discussed. Good fits to the
bulk properties of finite nuclei and single-particle spectra are obtained.


title: IS THERE A DOMAIN WALL PROBLEM?

abstract:
  We show that spontaneous breaking of discrete or continuous symmetries does
not necessarily imply either symmetry restoration or the thermal production of
defects at high temperature (at least up to $T \sim M_{Planck}$). This may
imply that there is no domain wall problem. As an example we show how this
applies to the Peccei-Quinn scenario.


title: Fermions Destabilize Electroweak Strings

abstract:
  Z-strings in the Weinberg-Salam model including fermions are unstable for all
values of the parameters. The cause of this instability is the fermion vacuum
energy in the Z-string background. Z-strings with non-zero fermion densities,
however, may still be stable.


title:
Can a Measurement of the $B_{s} - {\overline{B}}_{s}$ Mass Difference
  Establish the CKM Paradigm?

abstract:
  We present a reanalysis of the allowed region in the $\rho - \eta \,$ plane
of the CKM matrix, which follows from our present knowledge of the theoretical
and experimental parameters associated with quark mixing and CP violation.
Besides providing updated expectations for the angles of the unitarity
triangle, this reanalysis predicts a range of allowed values for the $B_{s} -
{\overline{B}}_{s} \,$ mass difference $\Delta m_{s}$. We argue that while
values of $\Delta m_{s} \lsim 10 (ps)^{-1}$ could be consistent with a non-CKM
origin for CP violation in the neutral Kaon system, larger values for $\Delta
m_{s}$ would provide strong support for the CKM paradigm.


title:
Reconstruction of the Extended Gauge Structure from $Z'$ Observables at
  Future Colliders

abstract:
  The discovery of a new neutral gauge boson $Z'$ with a mass in the TeV region
would allow for determination of gauge couplings of the $Z'$ to ordinary quarks
and leptons in a model independent way. We show that these couplings in turn
would allow us to determine the nature of the extended gauge structure. As a
prime example we study the $E_6$ group. In this case two discrete constraints
on experimentally determined couplings have to be satisfied. If so, the
couplings would then uniquely determine the two parameters, $\tan \beta$ and
$\delta$, which fully specify the nature of the $Z'$ within $E_6$. If the $Z'$
is part of the $E_6$ gauge structure, then for $M_{Z'}=1$ TeV $\tan \beta$ and
$\delta$ could be determined to around $10\%$ at the future colliders. The NLC
provides a unique determination of the two constraints as well as of $\tan
\beta$ and $\delta$, though with slightly larger error bars than at the LHC. On
the other hand, since the LHC primarily determines three out of four normalized
couplings, it provides weaker constraints for the underlying gauge structure.


title: $K \to 2 \pi$ Decay in the Nambu-Jona-Lasinio Model

abstract:
  We study the $K \to 2 \pi$ decays using the $U_L(3) \times U_R(3)$ version of
the Nambu-Jona-Lasinio model with the effective $\Delta S = 1$ nonleptonic weak
interaction. The $\Delta I = {3/2}$ amplitude is in reasonable agreement with
experimental data. On the other hand, the calculated $\Delta I = {1/2}$
amplitudes strongly depend on the mass of the low-lying scalar-isoscalar
$\sigma$ meson, and therefore give a strong constraint on the parameters of the
model.


title:
Two-Loop ${\cal O}(\alpha_sG_Fm_t^2)$ Corrections to Higgs Production at
  LEP

abstract:
  We evaluate the two-loop ${\cal O}(\alpha_sG_Fm_t^2)$ correction to the $ZZH$
coupling in the Standard Model by means of a low-energy theorem, assuming that
the top quark is much heavier than the Higgs boson. We then construct a
heavy-top-quark effective Lagrangian for the $ZZH$ interaction that
accommodates the ${\cal O}(G_Fm_t^2)$ and ${\cal O}(\alpha_sG_Fm_t^2)$
corrections and derive from it the corresponding corrections to the $H\to ZZ$
decay as well as those to Higgs-boson production at LEP1, via $Z\to f\bar fH$,
and at LEP2, via $e^+e^-\to ZH$. In all cases, the leading ${\cal O}(G_Fm_t^2)$
terms are considerably screened by their QCD corrections, if the on-shell
renormalization scheme with $G_F$ as a basic parameter is employed.


title:
The dilaton-dominated supersymmetry breaking scenario in the context of
  the non-minimal supersymmetric model

abstract:
  The phenomenological consequences of the dilaton-type soft supersymmetry
breaking terms in the context of the next to minimal supersymmetric standard
model are investigated. We always find a very low top quark mass. As a
consequence such string vacua are excluded by recent experimental results. The
viability of the solution of the $\mu$ term through the introduction of a gauge
singlet field is also briefly discussed.


title: Infra-red fixed points revisited

abstract:
  We reconsider how Yukawa couplings may be determined in terms of a gauge
coupling through the infra-red fixed point structure paying particular regard
to the rate of approach to the fixed point. Using this we determine whether the
fixed point structure of an underlying unified theory may play a significant
role in fixing the couplings at the gauge unification scale. We argue that,
particularly in the case of compactified theories, this is likely to be the
case and illustrate this by a consideration of phenomenologically interesting
theories. We discuss in particular what the infra-red fixed point structure
implies for the top quark mass.


title: Renormalisation-group invariance and soft supersymmetry-breaking

abstract:
  We show that a particular ``universal'' form for the soft-breaking couplings
in a softly broken $N=1$ supersymmetric gauge theory is renormalisation-group
invariant through two loops, provided we impose one simple condition on the
dimensionless couplings. The universal form for the trilinear couplings and
mass terms is identical to that found in popular derivations of the
soft-breaking terms from strings or supergravity.


title: $\Omega_0 <1$ From Inflation

abstract:
  An inflationary scenario that leads to $\Omega _0<1$ today is presented. An
epoch of `old' inflation during which the smoothness and horizon problems are
solved is followed by a shortened epoch of `new' inflation. Old inflation exits
through the nucleation of a single bubble, leading to negative spatial
curvature on slices of constant cosmic time. We calculate the spectrum of
density perturbations in such a scenario.


title: SU(3) String-Flip Potential Models and Nuclear Matter

abstract:
  For over 50 years attempts have been made to explain the properties of
nuclear matter in terms of constituent nucleons with very little success. Here
we will investigate one class of many possible models, string-flip potential
models, in which flux-tubes are connected between quarks (in a gas/plasma) to
give a minimal overall field configuration. A general overview of the current
status of these models, along with some of our recently finished work, shall be
given. It shall be shown that these models seem promising in that they do get
most of the bulk properties of nuclear matter correct with the exception of
nuclear binding. Finally we will conclude with a brief discussion on ways to
improve the string-flip potential models in an attempt to obtain nuclear
binding (currently we are investigating short range one-gluon exchange effects
-- some preliminary results shall be mentioned).


title: Finite-Sized Plasmas

abstract:
  When addressing the thermodynamics of finite-sized systems, one must specify
whether one wants to fix conserved charges to a sharp value or whether one is
content to fix their thermodynamic average. In other words, contrary to the
thermodynamic limit, different statistical ensembles are not equivalent. When
treating the plasma phases of gauge field theories perturbatively in the
canonical ensemble, unexpected new difficulties arise in comparison with the
usual grand canonical treatment. The purpose of this paper is to expose these
difficulties and show how they can be remedied, thus recovering a well-defined
description of plasmas even in a finite-size, canonical ensemble setting. For
definiteness, a specific model is considered, namely QCD$_{1+1} $ with SU(2)
color; however, the treatment presented should be applicable also to
higher-dimensional systems with different types of Coulomb interaction.


title: An Isobar Model of e+ e- --> pi+ pi- pi0 pi0

abstract:
  In this paper, several calculations of the matrix elements for processes that
may contribute to e+ e- --> pi+ pi- pi0 pi0 using the isobar model and the
Lorentz invariant amplitude method are presented. The formulas may be used to
determine the electromagnetic form factors of the rho meson if e+ e- --> rho+
rho- contributes to e+ e- --> pi+ pi- pi0 pi0 The electromagnetic form factors
of the rho meson are predicted by QCD calculations. The formulas in this paper
may be used to study the a_1 meson if e^+ e^- --> a_1 \pi contributes to e+ e-
--> pi+ pi- pi0 pi0.


title:
An attractive nucleon-nucleon spin-orbit force from skyrmions with
  dilatons

abstract:
  Within the skyrmion approach for the nucleon-nucleon force, difficulties have
been experienced in obtaining an isoscalar attractive spin-orbit potential, in
parallel to the problems of finding attraction in the isoscalar central
potential. We here study the spin-orbit force using a skyrmion with four- and
six-derivative stabilizing terms in the lagrangian as well as with the crucial
addition of a dilaton. With these features present the spin-orbit force proves
to be attractive as does the central potential. In the absence of the dilaton,
attraction can also be found for the spin-orbit potential but only at the
expense of a greatly over-emphasized term with six derivatives and a continuing
absence of attraction in the central potential.


title: Light Stops at CDF?

abstract:
  We study the possibility that the production and decay of light stop squarks
at Tevatron can mimic top events. We show that this scenario is very unlikely
to explain the anomalously high top production cross sections recently reported
by the CDF collaboration.


title: How reliable are the HQET-sum rule predictions?

abstract:
  We test the internal consistencies and the reliability of the existing
estimates of the decay constant $f_B$ in the static limit, the meson-quark mass
gap $\bar \Lambda$ and the kinetic energy $K$ of a heavy quark obtained from
the heavy quark effective theory (HQET)-sum rules. Finite energy local duality
sum rules (FESR) have also been used to fix $approximatively$ the value of the
continuum energy and to study the correlations among these different
parameters. Then, we deduce to two-loop accuracy: $\bl=(0.65\pm 0.05)$ GeV,
$K=-(0.5 \pm 0.2)$GeV^2$, implying the value of the pole mass in HQET: $M_b=
(4.61 \pm 0.05)$ GeV. By combining the results from the sum rules in HQET and
in the full theory, we obtain $f_B^\infty=(1.98 \pm 0.31)f_\pi$ and the
quadratic mass dependence of the pseudoscalar decay constant:
$f_P\sqrt{M_P}=(0.33 \pm 0.06)$GeV$^{3/2}\als^{1/\beta_1}2}\als^{1/\beta_1
1-2\als/3\pi-1.1/M_Q +0.7/M_Q^2 .$


title: CHIRAL SYMMETRY RESTORATION AS THE GEORGI VECTOR LIMIT

abstract:
  I discuss recent work done with Gerry Brown on chiral phase transition at
high temperature and/or density described in terms of Georgi's vector limit.
The notion of ``mended symmetry" is suggested to play an important role in
understanding the properties of hadrons in dense and/or hot matter before
reaching the phase transition. It is shown that while the QCD vacuum in
baryon-free space is resistant to ``melting" up to the critical temperature,
baryon-rich medium can induce the vacuum to become softer in temperature: the
hadron masses drop faster in temperature when baryon matter is present.


title: Refined Analysis of the Electroweak Precision Data

abstract:
  We refine our recent analysis of the electroweak precision data at the \PZO\
pole by including the hadronic decay modes of the \PZO. Within the framework of
an effective Lagrangian we parametrize $SU(2)$ violation by the additional
process-specific parameters $\De y_\nu$, $\De\yh$, and $\De\yb$ (for the
$\PZO\nu\bar\nu$, $\PZO\Pq\bar\Pq$, and $\PZO\Pb\bar\Pb$ vertices) together
with the previously introduced parameters $\De x$, $\De y$, and $\eps$. We find
that a six-parameter analysis of the experimental data is indeed feasible, and
it is carried out in addition to a four-parameter fit for $\De x$, $\De y$,
$\eps$, and $\De\yb$ only. We reemphasize that the experimental data have
become sensitive to the (combined) magnitude of the vertex corrections at the
$\PWp\Pl\bar\nu$ ($\PWm\nu\bar\Pl$) and $\PZO\Pl\bar\Pl$ vertices, $\De y$,
which is insensitive to the notion of the Higgs mechanism but dependent on the
non-Abelian, trilinear vector-boson coupling. Full explicit analytical results
for the standard one-loop predictions for the above-mentioned parameters are
given, and the leading two-loop top-quark effects are included. The analytic
formluae for the analysis of the experimental data in terms of the parameters
$\De x$, $\De y$ etc.\ are presented in order to encourage experimentalists to
persue such an analysis by themselves with future data.


title:
Hybrid and Conventional Mesons in the Flux Tube Model: Numerical Studies
  and their Phenomenological Implications

abstract:
  We present results from analytical and numerical studies of a flux tube model
of hybrid mesons. Our numerical results use a Hamiltonian Monte Carlo algorithm
and so improve on previous analytical treatments, which assumed small flux tube
oscillations and an adiabatic separation of quark and flux tube motion. We find
that the small oscillation approximation is inappropriate for typical hadrons
and that the hybrid mass is underestimated by the adiabatic approximation. For
physical parameters in the ``one-bead" flux tube model we estimate the lightest
hybrid masses (${}_\Lambda L = {}_1 P$ states) to be 1.8-1.9~GeV for $u\bar u$
hybrids, 2.1-2.2~GeV for $s\bar s$ and 4.1-4.2~GeV for $c\bar c$. We also
determine masses of conventional $q\bar q$ mesons with $L=0$ to $L=3$ in this
model, and confirm good agreement with experimental $J$-averaged multiplet
masses. Mass estimates are also given for hybrids with higher orbital and
flux-tube excitations. The gap from the lightest hybrid level (${}_1P$) to the
first hybrid orbital excitation (${}_1D$) is predicted to be $\approx 0.4$~GeV
for light quarks $(q=u,d)$ and $\approx 0.3$~GeV for $q=c$. Both ${}_1P$ and
${}_1D$ hybrid multiplets contain the exotics $1^{-+}$ and $2^{+-}$; in
addition the ${}_1P$ has a $0^{+-}$ and the ${}_1D$ contains a $3^{-+}$. Hybrid
mesons with doubly-excited flux tubes are also considered. The implications of
our results for spectroscopy are discussed, with emphasis on charmonium
hybrids, which may be accessible at facilities such as BEPC, KEK, a Tau-Charm
Factory, and in $\psi$ production at hadron colliders.


title:
Relativistic Bound State Equation for Unstable Fermions and the Toponium
  Width

abstract:
  The bound state problem for a fermion-antifermion system is considered taking
into account a finite decay width of the constituents. We propose an exactly
solvable relativistic zero order equation similar to that of Barbieri and
Remiddi, but including a constant width. We focus especially on the $t\bar{t}$
system for which we reconsider our recent calculation of the bound state
corrections to the toponium width, which was performed in the narrow width
approximation and needed the use of second order Bethe-Salpeter perturbation
theory. We show that one obtains the same result already in first order BS
perturbation theory if one uses our present approach. Furthermore the large
cancellations of gauge dependent terms is demonstrated to be a consequence of a
Ward identity. This cancellation mechanism is shown to be valid for general
fermion-antifermion systems.


title:
Lepton-Flavor Violation in the Supersymmetric Standard Model with
  Seesaw-Induced Neutrino Masses

abstract:
  We examine the lepton-flavor violation caused by a Yukawa coupling matrix
$y_{\nu,ij}$ for right-handed neutrinos in the supersymmetric standard model.
We stress that decay rates for $\tau\rightarrow\mu\gamma$ and $\mu\rightarrow
e\gamma$ may reach the range to be accessible to near future experiments if
left-right mixing terms in the slepton mass matrix are substantially large.


title: New Physics from U(3)-Family Nonet Higgs Boson Scenario

abstract:
  Being inspired by a phenomenological success of a charged lepton mass
formula, a model with U(3)-family nonet Higgs bosons is proposed. Here, the
Higgs bosons $\phi_L$ ($\phi_R$) couple only between light fermions (quarks and
leptons) $f_L$ ($f_R$) and super-heavy vector-like fermions $F_R$ ($F_L$), so
that the model leads to a seesaw-type mass matrix $M_f\simeq m_L M_F^{-1} m_R$
for quarks and leptons $f=u,d,\nu$ and $e$. Lower bounds of the physical Higgs
boson masses are deduced from the present experimental data and possible new
physics from the present scenario is speculated.


title: Systematic gauge invariant approach to heavy quarkonium decays

abstract:
  We present a method which, starting directly from QCD, permits a systematic
gauge-invariant expansion to be made for all hard processes involving quarkonia
in powers of the quark relative velocity, a small natural parameter for heavy
quark systems. Our treatment automatically introduces soft gluons in the
expansion. Corrections arising from the incorporation of gauge symmetry turn
out to be important for decay and fragmentation processes involving $Q \bar{Q}$
systems. The contribution of soft gluons is shown to be of higher order in $v$
and so is neglected for calculations done upto and including O($v^2$).


title:
Small-x physics and heavy quark photoproduction in the semihard approach
  at HERA

abstract:
  Processes of hevy quark photoproduction at HERA energies and beyond are
investigated using the semihard ($k_{\bot}$ factorization) approach. The
virtuality and longitudinal polarization of gluons in the photon - gluon
subprocess as well as the saturation effects in the gluon distribution function
at small $x$ have been taken into account. The total cross sections, rapidity
and $p_{\bot}$ distributions of the charm and beauty quark photoproduction have
been calculated. We obtained the some differences between the predictions of
the standard parton model and the semihard approach used here.


title:
Numerical cancellation of photon quadratic divergence in the study of
  the Schwinger-Dyson equations in Strong Coupling QED

abstract:
  The behaviour of the photon renormalization function in strong coupling QED
has been recently studied by Kondo, Mino and Nakatani. We find that the sharp
decrease in its behaviour at intermediate photon momenta is an artefact of the
method used to remove the quadratic divergence in the vacuum polarization. We
discuss how this can be avoided in numerical studies of the Schwinger-Dyson
equations.


title: Spectrum of elementary particles in a model of hadron supersymmetry

abstract:
  We investigate a spectrum of the low-energy composite particles with the
quantum numbers $J^p=0^\pm,\frac {1}{2}^\pm$ in a $SU_{F}(3)$ model of hadron
supersymmetry. We derive the mass spectrum of two, three and four-quark states
and determine all free parameters of a theory, including the masses of quarks
and diquarks.


title:
Effective Potentials and Symmetry Restoration in the Chiral Abelian
  Higgs Model

abstract:
  The chiral Abelian Higgs model is studied at finite temperature. By
integrating out the heavy modes, we make a three-dimensional effective theory
for the static modes. It is demonstrated that the plasma masses are correctly
reproduced to leading order in $m^{2}/T^{2}$. The effective potential for the
composite operator $\phi^{\dagger}\phi$ is calculated at one loop for the
resulting three-dimensional theory and it is shown that the result is gauge
parameter invariant. The numerical investigation of the potential reveals that
the symmetry is restored via a first order phase transition. Comparison with
the ordinary ring improved potential is made and it is found that the barrier
height at $T_{c}$ is somewhat higher.


title: The proton spin sum rule chiral bag prediction, an update

abstract:
  We reevaluate a quark model prediction using the new QCD evolution function
calculated to the 3 loop order and conclude that this model compares favorably
with the new experimental results.


title: Multiplicity Distributions in $b\rightarrow s\ gluon$ Decays

abstract:
  The final states for the process $b \rightarrow s\ \gamma$ have been
extensively discussed in the literature. Similarly-detailed analyses for the
case $b \rightarrow s\ gluon$ have not been performed. Generally this process
is searched for in 2-body decays such as ${\rm B}^0 \rightarrow {\rm K}^+
\pi^-$. We present simple arguments to suggest that most of the time the
quark-level process will give rise to final states with rather high
multiplicities. Comments are made about the applicability of these results to
$b \rightarrow d\ gluon$ and hadronic $b\rightarrow u$ decays.


title: A Method to Determine the Tau Neutrino Helicity Using Polarized Taus

abstract:
  A method is presented to extract the tau neutrino helicity, or equivalently,
the chirality parameter $\gamma_{\mathrm{VA}}$, independent of any tau
polarization which may be present. The method is thus well-suited to
measurements using taus produced from the $Z^0$ and is complementary to
analyses using tau correlations since it provides the sign of the chirality
parameter which is otherwise unavailable without recourse to lower energy
experiments where taus are unpolarized. Results of Monte Carlo studies and
comments regarding the use of the technique in experiments are also included.


title: Exploring $\pp$ scattering in the $\1N$ picture

abstract:
  In the large $N_c$ approximation to $QCD$, the leading $\pp$ scattering
amplitude is expressed as the sum of an infinite number of tree diagrams. We
investigate the possibility that an adequate approximation at energies up to
somewhat more than one $GeV$ can be made by keeping diagrams which involve the
exchange of resonances in this energy range in addition to the simplest chiral
contact terms. In this approach crossing symmetry is automatic but individual
terms tend to drastically violate partial wave unitarity. We first note that
the introduction of the $\rho$ meson in a chirally invariant manner
substantially delays the onset of drastic unitarity violation which would be
present for the {\it current algebra} term alone. This suggests a possibility
of local (in energy) cancellation which we then explore in a phenomenological
way. We include exchanges of leading resonances up to the $1.3 GeV$ region.
However, unitarity requires more structure which we model by a four derivative
contact term or by a low lying scalar resonance which is presumably subleading
in the $\1N$ expansion, but may nevertheless be important. The latter two
flavor model gives a reasonable description of the phase shift $\delta^0_0$ up
until around $860 MeV$, before the effects associated which the $K\bar{K}$
threshold come into play.


title:
A QCD TREATMENT OF THE WEAK DECAYS OF HEAVY FLAVOUR HADRONS -- WITHOUT
  VOODOO AND UNDUE INCANTATIONS

abstract:
  There now exist several theoretical technologies for treating weak decays of
heavy flavour hadrons that are genuinely based on QCD without having to invoke
a deus ex machina. I focus on one of those, which employs an expansion in
inverse powers of the heavy quark mass. It has developed into a rather mature
framework incorporating many subtle aspects of quantum field theory. I describe
its methodology for treating fully integrated decay rates as well as
differential distributions, in particular energy spectra; the importance of a
new type of sum rules, the SV sum rules, is emphasized. First practical
benefits from this theoretical technology are listed, like predictions on
lifetime ratios and extracting the KM parameter $|V(cb)|$ from inclusive and
from exclusive semileptonic $B$ decays. An outlook is given onto future
developments concerning the determination of the properly defined mass of the
heavy quark and its kinetic energy and a reliable extraction of
$|V(ub)/V(cb)|$. A few comments on charm decays are added.


title: Coupling Constant Unification in Extended SUSY Models

abstract:
  The unification of gauge coupling constants in the minimal supersymmetric
model (MSSM) is unaffected at the one-loop level by the inclusion of additional
mass-degenerate SU(5) multiplets. Perturbativity puts an upper limit on the
number of additional fields. We analyse the evolution of the gauge coupling
constants in all models satisfying these criteria using two-loop $\beta$
functions and including low energy threshold effects. We find that similarly to
the minimal supersymmetric model (MSSM) unification takes place within the
theoretical and experimental errors. The dominant proton decay mode is more
suppressed in all extended models as opposed to the MSSM due to renormalization
group effects. However, the prediction for the bottom to $\tau$ mass ratio
becomes worse in all models under consideration.


title: Isgur-Wise Function and Observables of $\Lambda_b$ Baryon

abstract:
  In connection with planned experiments devoted to investigation of
semileptonic decays of beauty baryons Isgur-Wise function and observables of
$\Lambda_b$ baryon (decay rates and distributions, leptonic spectra and
asymmetry parameters) are calculated in the framework of diquark model with
taking into account of infrared regime for heavy quark.


title: Implications of Electroweak Precision Tests

abstract:
  Invited Talk presented at the First Arctic Workshop on Particle Physics,
Saariselkae, August 1994 and at the Workshop on Elementary Particles and
Quantum Field Theory, Moscow, September 1994


title:
Excited Charmonium Decays by Flux-Tube Breaking and the $\psi^{'}$
  Anomaly at CDF

abstract:
  The hadronic decay of radially and orbitally excited charmonium above charm
threshold by $^3 P_{0}$ pair creation and chromoelectric flux--tube breaking is
discussed in an harmonic oscillator approximation. We find independent evidence
from a study of widths for a 2S admixture in the predominantly 1D state
$\psi(3770)$, and explore the possibility of metastable radially excited $2 \;
^{3}P_{0,1,2}$ states being a source of the anomalously large production of
$\psi^{'}$ at the Tevatron. At least one of them is expected to be narrow as a
consequence of the existence of nodes in the radial wave function.


title:
WW$\gamma$ and WWZ Production in $e^-e^-$ Collisions in the Left-Right
  Model

abstract:
  We have investigated the three vector boson production in electron-electron
collisions in the framework of the left-right symmetric electroweak model. The
process occurs due to lepton number violating interactions mediated by Majorana
neutrinos and triplet Higgs scalars. We find that only the reactions with a
heavy gauge boson pair in the final state, $e^-e^-\to W^{-}_2 W^{-}_2\gamma$
and $e^-e^- \to W^{-}_2 W^{-}_2Z^0_1$, are phenomenologically interesting from
the point of view of the Next Linear Collider. If the mass of $W_2^-$ is 0.5
TeV and the mass of the heavy Majorana neutrino of the order of 1 TeV, the
cross section of both reactions is in the range 1 to 10 fb at $\sqrt{s}= 2$
TeV, depending on the mass of the doubly charged triplet Higgs $\delta^{--}$,
yielding a 1 % background for the pair production of $W_2^-$. At the
$\delta^{--}$ resonance the cross section can be as large as 1 pb.


title: HIGGS PHENOMENOLOGY OF THE SUPERSYMMETRIC MODEL WITH A GAUGE SINGLET

abstract:
  We discuss the Higgs sector of the supersymmetric standard model extended by
a gauge singlet for the range of parameters, which is compatible with universal
soft supersymmetry breaking terms at the GUT scale. We present results for the
masses, couplings and decay properties of the lightest Higgs bosons, in
particular with regard to Higgs boson searches at LEP. The prospects differ
significantly from the ones within the MSSM.


title:
Tau Polarization in $ \Lambda_b \to X_c \tau \bar{\nu}$ and $B \to X_c
  \tau \bar{\nu}$

abstract:
  We discuss the longitudinal and transverse $\tau$-polarization in inclusive
decays of hadrons containing $b$-quarks. The calculation is performed by means
of an OPE in HQET. Some mathematical difficulties in calculating transverse
polarizations are explained. Numerical results are presented for longitudinal
and for transverse polarizations, both in and perpendicular to the decay plane.


title: Exclusive Photon-Induced Hadronic Reactions at Large Momentum Transfers

abstract:
  It is generally assumed that due to factorization of long- and short-distance
dynamics perturbative QCD can be applied to exclusive hadronic reactions at
large momentum transfers. Within such a perturbative approach diquarks turn out
to be a useful phenomenological device to model non-perturbative effects still
observable in the kinematic range accessible by present-days experiments. The
basic ingredients of the perturbative formalism with diquarks, i.e. Feynman
rules for diquarks and quark-diquark wave functions of baryons, are briefly
summarized. Applications of the diquark model to the electromagnetic form
factors of the proton in the space- as well as time-like region,
Compton-scattering off protons, gamma-gamma -> p-pbar, and photoproduction of
Kaons are discussed.


title: Thermalisation of Gauge Bosons in the Abelian Higgs Model

abstract:
  The thermalisation rate for long wavelength fluctuations of the gauge field
in the abelian Higgs model is calculated from the imaginary part of the self
energy. The calculation is performed for both the symmetric and symmetry broken
phase of the theory.


title:
Intermediate Scales in SUSY SO(10), b-\tau unification and Hot Dark
  Matter Neutrinos

abstract:
  Considerations of massive neutrinos, baryogenesis as well as fermion mass
textures in the grand unified theory framework provide strong motivations for
supersymmetric(SUSY) SO(10) as the theory beyond the standard model. If one
wants to simultaneously solve the strong CP problem via the Peccei-Quinn
mechanism, the most natural way to implement it within the framework of the
SUSY SO(10) model is to have an intermediate scale ($v_{BL}$) (corresponding to
B-L symmetry breaking) around the invisible axion scale of about 10$^{11}$ -
10$^{12}$ GeV. Such a scale is also desirable if $\nu_{\tau}$ is to constitute
the hot dark matter (HDM) of the universe. In this paper, we discuss examples
of superstring inspired SUSY SO(10) models with intermediate scales that are
consistent with the low energy precision measurements of the standard model
gauge couplings. The hypothesis of $b-\tau$ unification which is a successful
prediction of many grand unified theories is then required of these models and
the resulting prediction of $b$-quark mass is used as a measure of viability of
these schemes. Detailed analysis of a model with a $v_{BL}\simeq 10^{11}$ GeV,
which satisfies both the requirements of invisible axion and $\nu_{\tau}$ as
HDM is presented and shown to lead to $m_b\simeq 4.9$ GeV in the one-loop
approximation.


title:
SINGLE PHOTON DECAYS OF THE $Z^0$ AND SUSY WITH SPONTANEOUSLY BROKEN
  R-PARITY

abstract:
  Spontaneous violation of R parity can induce rare single photon decays of the
$Z^0$ involving the emission of (nearly) massless pseudoscalar Goldstone
bosons, majorons, as well as massive CP even or CP odd spin zero bosons that
arise in the electroweak breaking sector of these models. We show that the
majoron emitting decays can have a sizeable branching ratio of $10^{-5}$ or so,
without conflicting any experimental observation from neutrino physics or
particle searches. These decays may lead to interesting structures for the
single photon spectrum involving either mono chromatic photons as well as
continuous spectra that grow with energy. They would easily account for an
excess of single photon events at high energies recently hinted at by the OPAL
collaboration.


title: SIGNATURES FROM PHYSICS BEYOND THE STANDARD MODEL

abstract:
  A brief review is made of some of the experimental signatures that may be
associated to a certain class of extensions of the standard model. The material
of these lectures is divided into two sections. After briefly sketching the
present observational status of the neutrino masses I consider various schemes
of neutrino mass generation, including those which are motivated by present
experimental hints from solar and atmospheric neutrinos, as well as
cosmological data on the amplitude of primordial density fluctuations. Then
some of the physics motivations and potential of various extensions of the
standard model related to the electroweak breaking sector, such as
supersymmetry, and extensions of the gauge boson sector are reviewed. The new
signatures associated with both types of extension may all be accessible to
experiments performed either at accelerators or at underground installations.
The complementarity between these two approaches in the search for signals
beyond the standard model is most vividly manifest in the field of neutrino
physics.


title: BREAKUP OF HADRON MASSES AND ENERGY-MOMENTUM TENSOR OF QCD

abstract:
  Hadron masses are shown to be separable in QCD into contributions of quark
and gluon kinetic and potential energies, quark masses, and the trace anomaly.
The separation is based on a study of the structure of the QCD energy-momentum
tensor and its matrix elements in hadron states. The paper contains two parts.
In the first part, a detailed discussion of the renormalization properties of
the energy-momentum tensor is given. In the second part, a mass separation
formula is derived and then applied to the nucleon, pion, and the QCD vacuum.
Implications of the results on hadron structure and non-perturbative QCD
dynamics are discussed.


title: Can the Nambu-Goldstone Boson Live on the Light-Front?

abstract:
  We show that the Nambu-Goldstone(NG) boson restricted on the light-front(LF)
can only exist if we regularize the theory by introducing the explicit breaking
NG-boson mass $m_{\pi}$. The NG-boson zero mode, when integrated over the LF,
must have a singular behavior $\sim 1/m^2_{\pi}$ in the symmetric limit of
$m^2_{\pi}\rightarrow 0$. In the discretized LF quantization this peculiarity
is clarified in terms of the zero-mode constraints in the linear $\sigma$
model. The LF charge annihilates the vacuum, while it is not conserved in the
symmetric limit in the NG phase.


title: Sum rule of the correlation function

abstract:
  We derive a sum rule satisfied by the correlation function of two particles
with small relative momenta, which results from the completeness condition of
the quantum states.


title: Comment on the diagonalization of Green functions

abstract:
  Real-time thermal field theory is known in the two flavors ``closed-time path
formalism'' and ``thermo field dynamics''. With a certain choice of parameters
the full two-point functions of these models are identical, hence a scheme to
diagonalize the Green function in one model can be applied to the other as
well. This allows to compare the diagonalization schemes that have been
discussed in the recent literature in order to select the simplest one. Such
comparison speaks in favor of a diagonalization method which is motivated from
thermo field dynamics.


title: Baryon form factors in a diquark-quark bound state description

abstract:
  Nucleon form factors are calculated in a relativistic diquark--quark picture
based on the Nambu--Jona-Lasinio model. The nucleon wave function is obtained
in a static approximation to the quark exchange interaction between the valence
quark and the diquark. We evaluate the valence quark and $0^+$--diquark
contribution to the nucleon electromagnetic and weak currents. We find
reasonable electric charge radii, magnetic moments as in the additive diquark
model, and $g_A \approx 1$. We discuss the dependence on the model parameters.


title: The Kaon-Photoproduction Of Nucleons In The Quark Model

abstract:
  In this paper, we develop a general framework to study the
meson-photoproductions of nucleons in the chiral quark model. The S and U
channel resonance contributions are expressed in terms of the
Chew-Goldberger-Low-Nambu (CGLN) amplitudes. The kaon-photoproduction
processes, $\gamma p\to K^+ \Lambda$, $\gamma p\to K^+ \Sigma^0$, and $\gamma
p\to K^0\Sigma^+$, are calculated. The initial results show that the quark
model provides a much improved description of the reaction mechanism for the
kaon-photoproductions of the nucleon with less parameters than the traditional
phenomenological approaches.


title: Fermion Masses in a Supersymmetric SU(4)xSU(2)_LxSU(2)_R Model

abstract:
  We calculate quark and lepton masses and quark mixing angles in the framework
of a supersymmetric SU(4)$\otimes$SU(2)$_L\otimes$SU(2)$_R$ model where the
gauge group is broken at 10$^{16}$ GeV. The model predicts third family
top-bottom-tau Yukawa unification, as in minimal SO(10). The other smaller
Yukawa couplings are assumed to arise from non-renormalisable operators
suppressed by powers of some heavy scale. We perform a systematic operator
analysis of the model in order to find the minimum set of operators which
describe the low energy quark and lepton masses, and quark mixing angles
consistent with low-energy phenomenology. A novel feature of the model is the
possibility of asymmetric texture zeroes in the Yukawa matrices at the scale of
the new physics. Successful predictions are obtained for $m_t$, $\tan \beta$,
$m_s/m_\mu$, $m_d/m_e$ and $V_{ub}$ in terms of a CP violating phase $\phi$.
For example, we predict $\tan \beta = 35-65$, $m_t = 130 - 190$ GeV, and
$|V_{ub}|>0.0040$.


title:
Signals of extra gauge bosons and exotic leptons in
  SU(6)$_{L}\otimes$U(1)$_{Y}$

abstract:
  We study some of the consequences of the SU(6)$_{L}\otimes$U(1)$_{Y}$ model
of unification of electroweak interactions and families with a horizontal gauge
group SU(2)$_{H}$, paying special attention to processes with flavor changing
neutral currents. We compute at tree level the decays $K^{+}\longrightarrow
\pi^{+}\mu^{+}e^{-}$, $K_L^0\longrightarrow \mu^{+}e^{-}$ and $\mu^{-}
\longrightarrow e^{-} \bar{\nu_e} \nu_\mu$ from which we obtain lower bounds
for the mass of the horizontal gauge boson associated with FCNC. Finally we
obtain limits on the mixing between ordinary and exotic charged leptons.


title: Resonant neutrino oscillations and shock revival in type-II supernovae

abstract:
  The role of matter enhanced resonant neutrino oscillations in reviving a
stalled shock in a type-II supernova through delayed neutrino heating is
investigated. The extent of neutrino heating is estimated for the allowed
possibility of complete flavour conversion self-consistently with the changes
in nuclear equilibrium. The average internal energy per nucleon is
substantially increased indicating the possiblty of a robust explosion.


title:
Radiatively Generated Fermion Masses In $SU(4)\times SU(2)_L\times
  SU(2)_R$

abstract:
  We propose a model based on the gauge group $SU(4)\times SU(2)_L\times
SU(2)_R$ where the Dirac masses of all the known fermions are generated as
one-loop radiative corrections. We are able to generate realistic quark and
lepton masses and mixings without a large hierarchy of Yukawa couplings or
extra symmetries. The neutrino masses, which are see-saw suppressed, lie in the
mass range favored to solve the solar neutrino problem. The importance of
threshold corrections to tree-level mass relations in certain
non-supersymmetric GUTs is demonstrated.


title:
A Precision Calculation of the Next-to-Leading Order Energy-Energy
  Correlation Function

abstract:
  The O(alpha_s^2) contribution to the Energy-Energy Correlation function (EEC)
of e+e- -> hadrons is calculated to high precision and the results are shown to
be larger than previously reported. The consistency with the leading logarithm
approximation and the accurate cancellation of infrared singularities exhibited
by the new calculation suggest that it is reliable. We offer evidence that the
source of the disagreement with previous results lies in the regulation of
double singularities.


title:
Precision determination of $\alpha_s$ and $m_b$ from QCD sum rules for
  $b \overline b$.

abstract:
  The QCD sum rules for moments of production cross section of $b \overline b$
states in $e^+\,e^-$ annihilation are extremely sensitive to the values of
$m_b$ and $\alpha_s$ for moments of large order $n$. This enables one to
extract from the existing data on $\Upsilon$ resonances the values of these
parameters with a high precision by using a non-relativistic expansion in
$1/n$. It is found that the sum rules fit the data with $\alpha_s^{\overline
{MS}} (1 \, GeV) = 0.336 \pm 0.011$ and $m_b=4827 \pm 7 MeV$, where the
estimate of the errors includes the theoretical uncertainty due to subleading
in $1/n$ terms and the experimental uncertainty of the $e^+\,e^-$ annihilation
cross section above the $B \overline B$ threshold. The found value of
$\alpha_s$, when evolved in two loops up to the $Z$ mass, gives
$\alpha_s^{\overline {MS}} (M_Z) = 0.109 \pm 0.001$. The $b$ quark mass $m_b$
corresponds to the `on shell' value appropriate for one-loop perturbative
calculations.


title:
Effects of a heavy top quark on low energy data using the electroweak
  chiral Lagrangian

abstract:
  We study large top quark mass effects on low energy physics in the chiral
Lagrangian formulated electroweak theories. We show that these radiative
corrections can be easily obtained from a set of Feynman diagrams involving
only the scalar Goldstone bosons and the fermions when the contributions of the
order $g$ (the weak coupling) are ignored. Using CERN LEP and SLAC Linear
Collider (SLC) data we constrain on the nonstandard couplings, which might
originate from the spontaneous symmetry-breaking sector, of the top quark to
the electroweak gauge bosons.


title: Can a pseudo-symmetry solve the cosmological constant problem?

abstract:
  A general no-go theorem dampens hope that the cosmological constant problem
can be solved by a local symmetry mechanism. The possibility is considered here
that this no-go theorem can be avoided by a pseudo-symmetry. A simple
macroscopic effective field theory is constructed which admits an enhanced
pseudo-symmetry in the absence of a cosmological term. It is pointed out that
this pseudo-symmetry is an exact classical invariance of superstrings. The
conjecture that this pseudo-symmetry survives in the quantum theory has several
interesting consequences.


title: Baryon Mass Splittings in the 1/N_c Expansion

abstract:
  The $I=0,1,2,3$ mass splittings of the spin-$1/2$ octet and spin-$3/2$
decuplet baryons are analyzed in the $1/\N$ expansion combined with
perturbative flavor breaking. We show there is considerable experimental
evidence that the baryon masses satisfy the hierarchy predicted by this
expansion. Since flavor symmetry-breaking suppression factors alone are not
sufficient to describe the observed hierarchy, we conclude that there is firm
evidence for the $1/\N$ expansion in the baryon masses. Our analysis differs
from non-relativistic $SU(6)$.


title: Beyond the Standard Model

abstract: A few topics beyond the standard model are reviewed.


title: Cyclic Family Symmetry and Lepton Hierarchy in Supersymmetry

abstract:
  A cyclic symmetry among the left-handed doublets of the three families is
proposed. This symmetry can naturally result in a realistic hierarchical
pattern of the fermion masses within the framework of supersymmetry with
nonvanishing sneutrino vacuum expectation values.


title: Second Order Fermions in Gauge Theories

abstract:
  The second order formalism for fermions provides a description of fermions
that is very similar to that of scalars. We demonstrate that this second order
formalism is equivalent to the standard Dirac formalism. We do so in terms of
the conventional fermionic Feynman rules. The second order formalism has
previously proven useful for the computation of fermion loops, here we describe
how the corresponding rules can be applied to the calculation of amplitudes
involving external fermions, including tree-level processes and processes with
more than one fermion line. We comment on the supersymmetric identities
relating fermions and scalars and the associated simplifications to
perturbative calculations that are then more transparent.


title: INVESTIGATION OF $WW\gamma$ COUPLINGS

abstract:
  We investigated how measurements of weak boson production at high energy $ep$
and $e\gamma$ collisions can provide important information on anomalous
$WW\gamma$ couplings. We also considerd the sinlge muon production through the
virtual $W$-decay at the Pohang Light Source (PLS) facility, and found this
process is not adequate to be detected at the PLS until a large luminosity
($\sim 10^{33}$/sec/cm$^2$) Free Electron Laser is installed.


title: Spin Puzzle in Nucleon

abstract:
  The object of this brief review is to reconcile different points of view on
how the spin of proton is made up from its constituents. On the basis of naive
quark model with flavour symmetry such as isospin or SU(3) one finds a static
description. On the contrary the local SU(3) colour symmetry gives a dynamical
view. Both these views are contrasted and the role of U(1) axial anomaly and
the ambiguity for the measurable spin content is discussed.


title: CHARM CONTENT OF A PHOTON AND $J/\psi$ PHOTOPRODUCTION AT HIGH ENERGIES

abstract:
  A study of the $J/\psi$-meson production at large transverse momentum in high
energy $\gamma p$ collisions via the charm quark excitation in a photon is
presented. Based on perturbative QCD and the nonrelativistic quark model, our
calculation demonstrates that the charm content of a photon may be very
important for the $J/\psi$ photoproduction at the large transverse momentum. It
is shown that at HERA energies $J/\psi$ production via the subprocess $cg\to
J/\si c$ dominates over the resolved photon contribution via the subprocess
$gg\to J/\psi g$ at $p_{\bot}>3$ GeV/c and over the direct photon-gluon fusion
contribution at $p_{bot}>10$ GeV/c.