title: Subleading Corrections to Semileptonic Lambda_c Decays

abstract:
  The semileptonic decay $\Lambda_c \to \Lambda \ell \nu$ is considered in the
framework of heavy quark effective theory beyond the leading order in the
$1/m_c$ expansion. According to our estimate the polarization variable will
receive only very small corrections such that $\alpha_{\Lambda_c} \le -0.95$.


title: Quark Flavors as Entropy Ordered States of QCD

abstract:
  We discuss a natural notion of entropy in quantum field theory and apply it
to asymptotically free theories in their perturbative regimes. We then
specialize to QCD and find that quark flavor states can be described as
entropy--ordered states of QCD, and that the masses for the $s\bar{s}$--state,
charm, $c\bar{c}$--state, bottom and $b\bar{b}$--state can all be fitted by
requiring that the entropy of each of these states be the same. The resulting
Pearson correlation coefficient between theory and experiment is better than
0.99, and the known quark masses can be accounted for with less than an 8\%
error.


title:
Soft Photon Production Rate in Resummed Perturbation Theory of High
  Temperature QCD

abstract:
  We calculate the production rate of soft real photons from a hot quark --
gluon plasma using Braaten -- Pisarski's perturbative resummation method. To
leading order in the QCD coupling constant $g$ we find a logarithmically
divergent result for photon energies of order $gT$, where $T$ is the plasma
temperature. This divergent behaviour is due to unscreened mass singularities
in the effective hard thermal loop vertices in the case of a massless external
photon.


title: Flavor symmetry breaking in quark magnetic moments

abstract:
  We discuss the magnetic moments of the baryons allowing for flavor symmetry
breaking in the quark magnetic moments. We show that there is a correlation
between isospin symmetry breaking and data for the nucleon spin structure
obtained from deep inelastic scattering. For small values of the isospin
symmetry breaking, of the order of $5\%$, the magnetic moments and weak
axial-vector form factors alone indicate a value of the spin polarization
$\Delta\Sigma \leq 0.20$. Larger values of the spin polarization are compatible
only with large isospin symmetry breaking. We also calculate weak axial-vector
form factors, which are independent of the symmetry breakings, from magnetic
moment data and find good agreement with experiment.


title: Lifetimes of Charmed Hadrons Revisited. Facts and fancy

abstract:
  The problem of the hierarchy of lifetimes of charmed hadrons is reviewed. The
QCD-based theory of preasymptotic effects in inclusive weak decays dating back
to the beginning of the eighties is now entering its mature phase. Combining
recent and old results we argue that the observed hierarchy reflects most
intimate features of the hadronic structure. The problem of a wide spread of
lifetimes of charmed hadrons is addressed.
  We speculate on what is to be expected from QCD to provide the observed
pattern. A number of predictions is given for the hierarchy of lifetimes in the
family of the beautiful hadrons.


title:
One-Loop QCD Mass Effects in the Production of Polarized Bottom and Top
  Quarks

abstract:
  The analytic expressions for the production cross sections of polarized
bottom and top quarks in $e^+e^-$ annihilation are explicitly derived at the
one-loop order of strong interactions. Chirality-violating mass effects will
reduce the longitudinal spin polarization for the light quark pairs by an
amount of $3\%$, when one properly considers the massless limit for the final
quarks. Numerical estimates of longitudinal spin polarization effects in the
processes $e^+e^-\to b\bar{b}(g)$ and $e^+e^- \to t\bar{t}(g)$ are presented.


title: Finite Temperature Effective Potential in the Hartree-Fock Approximation

abstract:
  In order to investigate the nature of the phase transition, we study the
finite temperature effective potential for the $\lambda \Phi^4$ theory in the
Hartree-Fock approximation, which sums up all the daisy and superdaisy
diagrams.


title: On the Nature of the Abelian Higgs Model Phase Transition

abstract:
  The nature of the Abelian Higgs Model phase transition is investigated. A
variational approximation is used in the evaluation of the relevant finite
temperature effective potential. Some of the results presented are valid not
only in the Abelian Higgs Model, but also in more complex theories.


title: Non-Leptonic B Decays into K-Resonances

abstract:
  We estimate the non-leptonic B decays $B \rightarrow (\psi ,\psi^\prime ,
\chi_{1c})+K^i$, where $K^i$ are various K-meson resonances. We use the model
of Isgur, Wise, Scora and Grinstein in the context of heavy quark effective
theory, to calculate the hadronic matrix elements. Our estimates show that a
substantial fraction of $B \rightarrow X_s \psi$ results in higher resonances
of K-meson and besides $B \rightarrow K(K^*) \psi$, a considerable fraction of
$B \rightarrow X_s (c\bar c)$ goes to $B \rightarrow (K,K^*)+(
\psi^{\prime},\chi_{1c})$.


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

abstract:
  We exhibit a complementary relationship between resonant $WZ$ and nonresonant
$W^+W^+$ scattering in a chiral Lagrangian model of the electroweak symmetry
breaking sector with a dominant ``$\rho$'' meson. We use the model to estimate
the minimum luminosity for the LHC to ensure a ``no-lose'' capability to
observe the symmetry breaking sector.


title: Anathematizing the Guralnik and Manohar Inequality for \bar{\Lambda}

abstract:
  There is a recent claim by Guralnik and Manohar \cite{GM} to have established
a rigorous lower bound on $\bar \Lambda$, the asymptotic difference between the
mass of a heavy flavour {\em hadron} and that of the heavy flavour {\em quark}.
We point out the flaw in their reasoning and discuss the underlying physical
problem. An explicit counterexample to the GM bound is given; one can therefore
not count on a refined proof to re-establish this bound. *********** Uses LaTeX
No figures No macros file used.


title: Dynamical Generation of Fermion Mass Hierarchy

abstract:
  We describe a simple mechanism to break electroweak symmetry dynamically as
well as to generate a large fermion mass hierarchy. The mechanism is displayed
within the framework of a simple left-right symmetric model.
  The model has exact horizontal symmetry which is broken dynamically giving
rise to the mixing angles as well as to the fermion masses. The light fermions
acquire masses by exchange of the charged gauge bosons, which is possible in
the case of a left-right symmetric gauge group. We display a simple mechanism
to break the left-right symmetry. The stability of the horizontal symmetry
breaking solution is also discussed. We argue that if the gauge bosons are
massive then for a certain range of the gauge couplings the horizontal symmetry
breaking solution may be locally stable. We discuss some phenomenological
difficulties, in particular the question of unobserved Goldstone bosons, that
arise within the present model.


title: The Baffling Semileptonic Branching Ratio of $B$ Mesons

abstract:
  The apparent gap between the measured and the expected value for the
semileptonic branching ratio of $B$ mesons has become more serious over the
last year. This is due to the improved quality of the data and to the
increasing maturity of the theoretical treatment of non-perturbative
corrections. We discuss various theoretical options to reduce the semileptonic
$B$ branching ratio; among the more spectacular resolutions of the apparent
puzzle is the possibility of an unorthodox enhancement in non-perturbative
corrections or even of an intervention by `New Physics'. Phenomenological
implications of such scenarios are pointed out.


title:
Two-Loop Renormalization Group Equations for Soft Supersymmetry-Breaking
  Couplings

abstract:
  We compute the two-loop renormalization group equations for all soft
supersymmetry-breaking couplings in a general softly broken N=1 supersymmetric
model. We also specialize these results to the Minimal Supersymmetric Standard
Model.


title:
The Nonperturbative Regime in QCD Resummation for Gauge Boson Production
  at Hadron Colliders

abstract:
  We study the nonperturbative functions in the Collins--Soper--Sterman
resummation formalism by examing Drell--Yan data in both fixed target and
collider experiments and then predict the transverse momentum distributions of
the $W^\pm$ and $Z^0$ bosons at the Tevatron. Our results differ from that in
the literature and agree better with published CDF data. Using statistical
arguments, we find a $1\,$fb${}^{-1}$ luminosity at the Fermilab Tevatron
should be able to provide useful constraints on the nonperturbative functions.


title:
On Top Quark Polarization and Proposed Techniques for Measuring $m_t$ at
  Hadron Colliders

abstract:
  Measuring the top quark mass in its semileptonic decay mode, $t ->be^+\nu$
($b -> \mu^- + X$), through the mass distribution of the $e^+$--$\mu^-$ pair
has been shown to provide a good measurement of the top quark mass with an
uncertainty of $1.6\%$ for $m_t=150,250\,$GeV at the SSC. Here it is
demonstrated that an uncertainty in the polarization of the top quark can add
an additional uncertainty of about $3%$ in the mass. [Talk presented at the
Workshop on Physics at Current Accelerators and the Supercollider held at the
Argonne National Laboratory, Argonne, Illinois, 2-5 June 1993.]


title: Perturbative Hot Gauge Theories - Recent Results

abstract:
  Current results in high temperature gauge theories obtained in the context of
the perturbative method of resumming hard thermal loops are reviewed. Beyond
leading order properties of the gluon excitation, and the recent
(controversial) calculations of the damping rates are discussed. QCD
predictions on plasma signatures are exemplified by the thermal production
rates of energetic as well as soft photons. [Talk given at the 3rd Workshop on
Thermal Field Theories and their Applications, August 15--27, 1993, Banff,
Alberta, Canada]


title: The QCD String with Quarks. I.Spinless Quarks

abstract:
  Starting from the QCD Lagrangian we derive the effective action for massive
quark and antiquark at large distances, corresponding to the minimal area low
of the Wilson loop. The path integral method is used to quantize the system and
the spectrum is obtained with asymptotically linear Regge trajectories. Two
dynamical regimes distinguished by the string energy--momentum distribution are
found: at large orbital excitations ($l\gg 1$) the system behaves as a string
and yields the Regge slope of $\frac{1}{2 \pi \sigma}$, while at small $l$ one
obtains a potential-like regime for relativistic or nonrelativistic system .
The problem of relative time is clarified. It is shown that in the valence
quark approximation one can reduce the initial four-dimensional dynamics to the
three-dimensional one. The limiting case of a pure string (without quark
kinetic terms) is studied and the spectrum of the straight-line string is
obtained.


title:
Theoretical Uncertainties and Phenomenological Aspects of $B \rightarrow
  X_s \gamma$ Decay

abstract:
  We analyze uncertainties in the theoretical prediction for the inclusive
branching ratio $BR[B \rightarrow X_s \gamma]$. We find that the dominant
uncertainty in the leading order expression comes from its $\mu$-dependence. We
discuss a next-to-leading order calculation of $B \rightarrow X_s \gamma$ in
general terms and check to what extent the $\mu$-dependence can be reduced in
such a calculation. We present constraints on the Standard and
Two-Higgs-Doublet Model parameters coming from the measurement of $b
\rightarrow s \gamma$ decay. The current theoretical uncertainties do not allow
one to definitively restrict the Standard Model parameters much beyond the
limits coming from other experiments. The bounds on the Two-Higgs-Doublet Model
remain very strong, though significantly weaker than the ones present in the
recent literature. In the Two-Higgs-Doublet Model case, the $b \rightarrow s
\gamma$, $Z \rightarrow b \bar{b}$ and $b \rightarrow c \tau \bar{\nu}_{\tau}$
processes are enough to give the most restrictive bounds in the
$M_{H^{\pm}}-tan \beta$ plane.


title: Aspects of the Cosmological Electroweak Phase Transition

abstract:
  We study the decay of the metastable symmetric phase in the standard model at
finite temperature. For the SU(2)-Higgs model the two wave function correction
terms $Z_{\vp}(\vp^2,T)$ and $Z_{\chi}(\vp^2,T)$ of Higgs and Goldstone boson
fields are calculated to one-loop order. We find that the derivative expansion
of the effective action is reliable for Higgs masses smaller than the W-boson
mass. We propose a new procedure to evaluate the decay rate by first
integrating out the vector field and the components of the scalar fields with
non-zero Matsubara frequencies. The static part of the scalar field is treated
in the saddle point approximation. As a by-product we obtain a formula for the
decay rate of a homogeneous unstable state. The course of the cosmological
electroweak phase transition is evaluated numerically for different Higgs boson
masses and non-vanishing magnetic mass of the gauge boson. For Higgs masses
above $\sim 60$ GeV the latent heat can reheat the system to the critical
temperature which qualitatively changes the nature of the transition.


title:
Gluonium as Bound State of Massive Gluons Described by the Joos-Weinberg
  Wave Functions

abstract:
  On the basis of the Kadyshevsky equal-time (quasipotential) approach, a set
of partial-wave equations is derived for the wave function of a gluonium, a
bound state of two gluons. The field operators of constituent gluons are
considered as six component quantities according to the Joos-Weinberg
$2(2S+1)$- component approach. The quasiclassical quantization condition for
relativistic two-particle states and the above set could be used for
calculations of gluonium energy levels.


title: Two Heavy Quark Effective Theories

abstract:
  We point out that there exist two different formulations of the Heavy Quark
Effective Theory (HQET). One formulation of HQET was mostly developed at
Harvard and involves the use of the equation of motion to eliminate the small
components of the heavy quark field. The second formulation, developed in
Mainz, involves a series of Foldy-Wouthuysen-type field transformations which
diagonalizes the heavy quark Lagrangian. Starting at O($1/m_Q^2$) the two
formulations are different in that their effective Lagrangians, their effective
currents, and their fields differ. However, when these three differences are
properly taken into account, the two alternative formulations lead to identical
S-matrix elements. This is demonstrated in an explicit example at O($1/m_Q^2$).
We point to an essential difficulty of the Harvard HQET in that the Harvard
effective fields are not properly normalized starting at order $O(1/m_Q^2)$.


title:
What do heavy-light ($ Q\bar{q} $) quark systems tell us about QCD
  vacuum properties?

abstract:
  Arguments in favor of a large magnitude ( at least two- three times bigger
than its factorized value) of the mixed vacuum condensate $ \la
\bar{q}G_{\mu\nu}^a G_{\mu\nu}^a q \ra$ are given. The analysis is based on the
strict inequalities which follow from the QCD sum rules method and on very
plausible phenomenological assumptions like $ m_{B_s} > m_{B_u} $ for the few
lowest exited $ Q\bar{q} $ states in a heavy quark limit $m_Q\rightarrow\infty
$. The same arguments show the suppression of the $SU(3)$ symmetry breaking
effects for vacuum condensates when the additional gluon fields are included.


title: QCD and the Chiral Critical Point

abstract:
  As an extension of $QCD$, consider a theory with ``$2+1$'' flavors, where the
current quark masses are held in a fixed ratio as the overall scale of the
quark masses is varied. At nonzero temperature and baryon density it is
expected that in the chiral limit the chiral phase transition is of first
order. Increasing the quark mass from zero, the chiral transition becomes more
weakly first order, and can end in a chiral critical point. We show that the
only massless field at the chiral critical point is a sigma meson, with the
universality class that of the Ising model. Present day lattice simulations
indicate that $QCD$ is (relatively) near to the chiral critical point.


title:
The Phenomenology of a Hidden Symmetry Breaking Sector at
  Electron-Positron Colliders

abstract:
  We calculate the production rate of gauge-boson pairs at $e^+e^-$ colliders
in a model with a ``hidden'' electroweak symmetry breaking sector - i.e. one in
which there are a large number of particles in the symmetry breaking sector
other than the $W^{\pm}$ \thinspace and the $Z^0$. In such a model, the elastic
$W^{\pm}$ \thinspace and $Z^0$ scattering amplitudes are small and
structureless, i.e. lacking any discernable resonances, at all energies. We
show that two gauge boson fusion signal of electroweak symmetry breaking is
swamped by the background. Therefore, we cannot rely on gauge boson pairs as a
signal of the dynamics of symmetry breaking.


title: Small SUSY phases in string-inspired supergravity

abstract:
  In supersymmetric models, there are new CP violating phases which, if
unsuppressed, would give a too large neutron electric dipole moment. We examine
the possibility of small SUSY phases in string-inspired supergravity models in
which supersymmetry is broken by the auxiliary components of the dilaton and
moduli superfields. It is found that the SUSY phases can be suppressed by a
small factor governing the breakdown of the approximate Peccei Quinn symmetries
nonlinearly realized for the moduli superfields that participate in
supersymmetry breaking. In many cases, the symmetry breaking factors are
exponentially small for moderately large values of the moduli, leading to small
phase values in a natural way.


title:
The Exact Critical Bubble Free Energy and the Effectiveness of Effective
  Potential Approximations

abstract:
  To calculate the temperature at which a first-order cosmological phase
transition occurs, one must calculate $F_c(T)$, the free energy of a critical
bubble configuration. $F_c(T)$ is often approximated by the classical energy
plus an integral over the bubble of the effective potential; one must choose a
method for calculating the effective potential when $V''<0$. We test different
effective potential approximations at one loop. The agreement is best if one
pulls a factor of $\mu^4/T^4$ into the decay rate prefactor [where $\mu^2 =
V''(\phi_f)$], and takes the real part of the effective potential in the region
$V''<0$. We perform a similar analysis on the 1-dimensional kink.


title: Aspects of Nucleon Compton Scattering

abstract:
  We consider the spin-averaged nucleon forward Compton scattering amplitude in
heavy baryon chiral perturbation theory including all terms to order ${\cal O}
(q^4)$. The chiral prediction for the spin-averaged forward Compton scattering
amplitude is in good agreement with the data for photon energies $\omega \le
110$ MeV. We also evaluate the nucleon electric and magnetic Compton
polarizabilities to this order and discuss the uncertainties of the various
counter terms entering the chiral expansion of these quantities.


title: New classes of summable Skyrmions

abstract:
  We introduce two new classes of summable Skyrmions. The Lagrangians they
originate from are explicitely constructed. We also analyse how some models
could be solve. Exact solutions are found for Skyrme-like toy models.


title: Model Independent $Z'$ Constraints at Future $e^+e^-$ Colliders}

abstract:
  Model independent constraints on the mass of extra neutral gauge bosons and
their couplings to charged leptons are given for LEP~II and a 500\,GeV $e^+e^-$
collider. Analytical exclusion limits are derived in the Born approximation.
The $Z'$ limits obtained with radiative corrections are always worse than those
calculated at the Born level. Polarized beams are only useful for degrees of
polarization essentially larger than 50\%. Known discovery limits on extra $Z$
bosons predicted by popular $Z'$ models are reproduced as special cases. The
$Z'$ constraints are compared to those predicted by four fermion contact
interactions.


title:
Leading Order QCD Corrections to $b\rightarrow s \, \gamma$ and $b
  \rightarrow s \, g$ Decays in Three Regularization Schemes

abstract:
  We discuss in detail the calculation of the leading order QCD corrections to
the Effective Hamiltonian which governs $b \rightarrow s\, \gamma$ and $b
\rightarrow s \, g$ transitions in three different regularization schemes (HV,
NDR and DRED). We show that intermediate stages of the calculation do depend on
the regularization, but the same scheme independent coefficients can be
obtained in all the considered schemes. A detailed discussion of the results
already present in the literature is also given.


title:
Thermal Background Corrections to the Neutrino Electromagnetic Vertex in
  Models with Charged Scalar Bosons

abstract:
  We calculate the correction to the neutrino electromagnetic vertex due to
background of electrons in a large class of models, as the supersymmetric model
with explicit breaking of R-parity, where charged scalar bosons couple to
leptons and which are able to provide an astrophysically interesting value for
the neutrino magnetic (electric) moment, $\mu_\nu\sim 10^{-12}\:\mu_B$. We show
that the medium contribution to the chirality flipping magnetic (electric)
dipole moment is not significant, however a new chirality flipping, but
helicity conserving, term arises. It signals the presence of ${\cal CP}$ and
${\cal CPT}$ asymmetries in the medium and is associated to the longitudinal
photon and therefore disappears in the vacuum. We estimate the contribution of
this new term to the rate of the plasmon decay process $\gamma_{pl}\rightarrow
\nu\nu$ in the core of degenerate stars, showing that it can be comparable with
the contribution coming from the vacuum magnetic (dipole) moment. We also
calculate the correction to the effective potential of a propagating neutrino
in presence of a magnetic field due to a chirality preserving contribution to
the diagonal magnetic moment from the medium. This contribution is identical
for particles and antiparticles and so need not to vanish for Majorana
neutrinos.


title: Results from Neutrino Experiments

abstract:
  Recent (first or/and the best) results from the neutrino experiments are
reviewed and their implications for the theory are discussed. The sense of the
experiments is the searching for neutrino masses, mixing and interactions
beyond the standard model. Present laboratory experiments give upper bounds on
the masses and the mixing which are at the level of predictions of the
``electroweak see-saw". Positive indications of nonzero lepton mixing follow
from studies of the solar and atmospheric neutrinos.


title:
Neutrino properties from maximally-predictive GUT models and the
  structure of the heavy Majorana sector

abstract:
  Starting from a complete set of possible parametrisations of the quark-mass
matrices that have the maximum number of texture zeros at the grand unification
scale, and the Georgi-Jarlskog mass relations, we classify the neutrino spectra
with respect to the unknown structure of the heavy Majorana sector. The results
can be casted into a small number of phenomenologically distinct classes of
neutrino spectra, characterised by universal mass-hierarchy and oscillation
patterns. One finds that the neutrino masses reflect the natural hierarchy
among the three generations and obey the quadratic seesaw, for most GUT models
that contain a rather unsophisticated Majorana sector. A scenario with
$\nu_{\tau}$ as the missing hot dark matter component and $\nu_e\leftrightarrow
\nu_{\mu}$ oscillations accounting for the solar neutrino deficit comes
naturally out of this type of models and is very close to the experimental
limit of confirmation or exclusion. In contrast, in the presence of a strong
hierarchy of heavy scales or/and some extra symmetries in the Majorana mass
matrix, this natural hierarchy gets distorted or even reversed. This fact can
become a link between searches for neutrino oscillations and searches for
discrete symmetries close to the Planck scale.


title: Anomalies without Massless Particles

abstract:
  Baryon and lepton number in the standard model are violated by anomalies,
even though the fermions are massive. This problem is studied in the context of
a two dimensional model. In a uniform background field, fermion production
arise from non-adiabatic behavior that compensates for the absence of massless
modes. On the other hand, for localized instanton-like configurations, there is
an adiabatic limit. In this case, the anomaly is produced by bound states which
travel across the mass gap. The sphaleron corresponds to a bound state at the
halfway point.


title: Supergravity Models

abstract:
  Theoretical and experimental motivations behind supergravity grand unified
models are described. The basic ideas of supergravity, and the origin of the
soft breaking terms are reviewed. Effects of GUT thresholds and predictions
arising from models possessing proton decay are discussed. Speculations as to
which aspects of the Standard Model might be explained by supergravity models
and which may require Planck scale physics to understand are mentioned.


title: Full O(alpha) Radiative Corrections to High-Energy Compton Scattering

abstract:
  Using computer-algebraic methods we derive compact analytical expressions for
the virtual electroweak radiative corrections to polarized Compton scattering.
Moreover the helicity amplitudes for double Compton scattering, which prove to
be extremely simple in terms of Weyl-van der Waerden spinor products, are
presented for massless electrons. The inclusion of a finite electron mass is
described, too. Finally numerical results both for the purely photonic and the
full O(alpha) electroweak corrections, which turn out to be of the order of
5-10%, are discussed for energies ranging from 10GeV to 2TeV.


title: The Retarded-Advanced basis in the Real Time formalism

abstract:
  A review of the properties of this alternate basis is presented. To appear in
the proceedings of the 3rd Workshop on Thermal Field Theory, Banff, August
1993.


title: An Instanton-Induced Contribution to the Decay of the Eta_c into P-Pbar

abstract:
  We compute the decay rate for the process $\eta_c\to p\bar p$ using an
effective helicity-flipping proton-antiproton-gluon vertex which incorporates
nonperturbative chiral symmetry breaking effects induced by instantons. We fix
the strength of the vertex by requiring it to account for the screening of the
proton's axial charge observed in deep-inelastic scattering, and we estimate
the size of the instanton effects by assuming them to depend linearly on the
instanton density. We find that, despite a large suppression, the
instanton-induced process occurs with a sizable rate comparable to the observed
one, whereas the process is forbidden in perturbative QCD and not understood
using standard methods.


title:
The Mass of the Lightest Supersymmetric Higgs Boson beyond the Leading
  Logarithm Approximation

abstract:
  We examine the radiative corrections to the mass of the lightest Higgs boson
in the minimal supersymmetric extension of the standard model. We use the
renormalization-group improved effective potential which includes the
next-to-leading-order contributions. We find that, contrary to the result of
Espinosa and Quir\'os, the higher-order corrections to the lightest Higgs boson
mass are non-negligible, adding $3-11$ GeV ($3-9$ GeV) to the result in the
leading logarithm approximation for the range of top quark mass $100 {\rm GeV}
< m_t < 200 {\rm GeV}$ and for the supersymmetric breaking scale $M_{\rm SUSY}
= 1 {\rm TeV}$ ($M_{\rm SUSY} = 10 {\rm TeV}$). Also we find that our result is
stable under the change of the renormalization parameter $t$.


title: Strong Sphalerons and Electroweak Baryogenesis

abstract:
  We analyze the spontaneous baryogenesis and charge transport mechanisms
suggested by Cohen, Kaplan and Nelson for baryon asymmetry generation in
extended versions of electroweak theory. We find that accounting for
non-perturbative chirality-breaking transitions due to strong sphalerons
reduces the baryonic asymmetry by the factor $(m_t/\pi T)^2$ or $\alpha_W$,
provided those processes are in thermal equilibrium.


title: Monte Carlo Approach to Radiative Corrections in Bhabha Scattering

abstract:
  A new Monte Carlo model is proposed for radiative corrections to Bhabha
scattering by extending QEDPS developed for multi-photon emission in muon pair
production in $e^+e^-$ annihilation. This is the QED version of the model known
as parton shower in QCD. The main difference between muon pair production and
Bhabha scattering is that the latter cross section shows the singularity of
$1/t^2$. A shower algorithm is constructed on the radiator formalism modified
in a suitable form for this singularity. Some results of the model are
presented and compared with $O(\alpha)$ corrections.


title:
Evaluation of the One-loop Effective Action at Zero and Finite
  Temperature

abstract:
  A method for determining the leading quantum contributions to the effective
action for both zero and finite temperatures is presented. While it is
described in the context of a scalar field theory, it can be straight-forwardly
extended to include fermions. An extrapolation procedure which can
significantly enhance the computational efficiency is introduced. This
formalism is used to investigate quantum corrections to the nucleation rate in
first-order phase transitions.


title:
Unitarity Constraints for Transverse Gauge Bosons at LEP and
  Supercolliders

abstract:
  Using asymptotic helicity amplitudes for Vector-Vector, Vector-Higgs and
Higgs-Higgs scattering, we establish the unitarity constraints on the $SU(2)_c$
conserving and $W_\mu$ depending interactions, which at sufficiently high
energies may create strong forces among the transverse vector boson and Higgs
states. We then derive upper bounds for the couplings of these interactions,
which depend on the high energy scale where unitarity is saturated. If \eg\,
unitarity is saturated at 1TeV, then $\lambda_W \lsim 0.12$ is obtained. The
implied relations between the present and future LEP results, and the possible
observations of strong effects at supercolliders, are also discussed


title: Discrete Symmetries, Strong CP Problem and Gravity

abstract:
  Spontaneous breaking of parity or time reversal invariance offers a solution
to the strong CP problem, the stability of which under quantum gravitational
effects provides an upper limit on the scale of symmetry breaking. Even more
important, these Planck scale effects may provide a simple and natural way out
of the resulting domain wall problem. (Invited talk at the 4th Hellenic School
on Elementary Particle Physics, Corfu, Greece, September 1992.


title: Heavy Charged Higgs Signals at the LHC

abstract:
  We discuss the viability of $gb \to tH \to ttb$ charged-Higgs signals at the
proposed LHC $pp$ supercollider, in the decay channel $tt \to (bq \bar q')(b
\ell \nu)$. Here one top quark decays hadronically and one semileptonically,
with all three $b$-quarks giving flavor-tagged jets. The principal backgrounds
come from $ttg,ttq,ttc$ and $ttb$ continuum production, with possible
mis-tagging of $g,q$ and $c$. We conclude that significant signals can be
separated from these backgrounds, for limited but interesting ranges of the
parameters $m_{H\pm}$ and $\tan\beta$, with the LHC energy and luminosity.


title: Parameterisation (and Gauge) Invariance of the Transition Temperature

abstract:
  The so-called Unitary Gauge Puzzle is re-examined in the light of a set of
gauge dependence identities discovered by Kobes, Kunstatter and Rebhan. The
``puzzle'' is discovered to arise as an artifact of the gauge-variant and
off-shell nature of the Effective Potential. An explicit analysis of the scalar
sector of the Abelian Higgs model shows that the correct physical result is
obtained in all cases provided that the calculation is performed
self-consistently, and the result is evaluated on-shell.


title: Fermion sea along the sphaleron barrier

abstract:
  In this revised version we have improved the treatment of the top and bottom
quark mass. This leads to slight changes of the numerical results, especially
of those presented in Fig.4. The discussion of the numerical procedure and
accuracy has been extended.


title: V,W and X in Technicolour Models

abstract:
  Light techni-fermions and pseudo Goldstone bosons that contribute to the
electroweak radiative correction parameters V,W and X may relax the constraints
on technicolour models from the experimental values of the parameters S and T.
Order of magnitude estimates of the contributions to V,W and X from light
techni-leptons are made when the the techni-neutrino has a small Dirac mass or
a large Majorana mass. The contributions to V,W and X from pseudo Goldstone
bosons are calculated in a gauged chiral Lagrangian. Estimates of V,W and X in
one family technicolour models suggest that the upper bounds on S and T should
be relaxed by between 0.1 and 1 depending upon the precise particle spectrum.


title: Implications of Scaling Violations of F2 at HERA for Perturbative QCD

abstract:
  We critically examine the QCD predictions for the $Q^2$ dependence of the
electron-proton deep-inelastic structure function $F_2(x,Q^2)$ in the small $x$
region, which is being probed at HERA. The standard results based on
next-to-leading order Altarelli-Parisi evolution are compared with those that
follow from the BFKL equation, which corresponds to the resummation of the
leading log$(1/x)$ terms. The effects of parton screening are also quantified.
The theoretical predictions are confronted with each other, and with existing
data from HERA. (3 Postscript figures included).


title:
Singular defects with fractional topological charge\\ in $\sigma$ models
  and gauge theories

abstract:
  A novel class of self-dual solutions in $\sigma$ models and gauge theories is
considered. The contribution of the corresponding fluctuations to the chiral
condensate is calculated. We discuss the few tightly connected problems, such
as the $U(1)$ problem, the $\theta$ dependence and the chiral symmetry breaking
within a framework of this approach. Arguments in favour of significance of the
configurations with fractional topological charge are given.


title: Recent Progress in the Theory of Heavy Flavor Production

abstract:
  We review some recent results on heavy quark production in high energy
hadronic collisions. We will discuss in particular the status of production
cross sections for bottom quarks and charmonium states and will present some
studies on the production of bottom and charm jets, at the inclusive level and
in association with electroweak gauge bosons.


title: Anomalous Condensates and the Equivalence Theorem

abstract:
  A recently published report has called into question the validity of the
equivalence theorem in dynamically broken gauge theories in which the fermions
making up the symmetry breaking condensate lie in an anomalous representation
of the broken gauge group. Such a situation can occur if the gauge anomaly is
cancelled by another sector of the theory. Using the example of the one family
Standard Model without scalar Higgs structure, we analyze a low energy
effective theory which preserves the symmetries of the fundamental theory and
demonstrate the validity of the equivalence theorem in this class of models.


title:
Detecting the $tb$ Decays of a Charged Higgs Boson at a Hadron
  Supercollider

abstract:
  We demonstrate that detection of a charged Higgs boson decaying via $\hpm\rta
t b$ will be possible at the LHC in $gg\rta \hm t \anti b+\hp b\anti t$ events,
provided the $\hp\rta t\anti b$ coupling is substantial, $\mt\gsim 110\gev$,
and reasonably efficient and pure $b$-tagging can be performed.


title:
The Potential of a New Linear Collider for the Measurement of the
  Trilinear Couplings among the Electroweak Vector Bosons

abstract:
  We study the accuracy to be obtained in measuring trilinear $Z^0W^+W^-$ and
$\gamma W^+W^-$ couplings in the reaction $e^+e^- \to W^+W^-$ at "New Linear
Collider" energies of $500GeV$ to $1000GeV$. We derive simple scaling laws for
the sensitivity in the measurement of these couplings. For most couplings the
sensitivity increases as $\sqrt{L\cdot s}$, where $L$ denotes the integrated
luminosity and $\sqrt s$ denotes the $e^+e^-$ center-of-mass energy. Detailed
investigations based on various fits confirm these scaling laws and show that
an accuracy of the order of the standard radiative corrections can be reached
at the NLC for the design values of the luminosity.


title:
The Momentum--Space Bosonization of the Nambu--Jona-Lasinio Model with
  Vector and Axial-Vector Mesons

abstract:
  The momentum-space bosonization method is extended to the case of a
Nambu--Jona-Lasinio type model with vector and axial-vector mesons. The method
presented gives the possibility of deriving any meson vertex function to all
orders in momenta and to the leading order in $1/N_c$. Two-point functions,
which describe one-particle transitions to the hadronic vacuum, and meson
self-energies are considered. We find new relations which generalize the
well-known KSFR relation and both the first and the second Weinberg sum rules.
These result from a consistent treatment of higher order terms in the momentum
expansion.


title: The Electric Charge of Neutrinos and Plasmon Decay

abstract:
  By using both thermal field theory and a somewhat more intuitive method, we
define the electric charge as well as the charge radius of neutrinos
propagating inside a plasma. We show that electron neutrinos acquire a charge
radius of order $\sim 6.5 \times 10^{-16}$ cm, regardless of the properties of
the medium. Then, we compute the rate of plasmon decay which such an electric
charge or a charge radius implies. Taking into account the relativistic effects
of the degenerate electron gas, we compare our results to various
approximations as well as to recent calculations and determine the regimes
where the electric charge or the charge radius does mediate the decay of
plasmons. Finally, we discuss the stellar limits on any anomalous charge radius
of neutrinos.


title: Heavy Quarkonium Potential Model and the ${}^1P_1$ State of Charmonium

abstract:
  A theoretical explanation of the observed splittings among the P~states of
charmonium is given with the use of a nonsingular potential model for heavy
quarkonia. We also show that the recently observed mass difference between the
center of gravity of the ${}^3P_J$ states and the ${}^1P_1$ state of $c\bar{c}$
does not provide a direct test of the color hyperfine interaction in heavy
quarkonia. Our theoretical value for the mass of the ${}^1P_1$ state is in
agreement with the experimental result, and its E1 transition width is
341.8~keV. The mass of the $\eta_c'$ state is predicted to be 3622.3~MeV.


title:
First Constraints on SU(5)xU(1) Supergravity from Trilepton Searches at
  the Tevatron

abstract:
  We present the first constraints on the parameter space of $SU(5)\times U(1)$
supergravity (in both no-scale and dilaton scenarios) which arise from the
recently announced limits on trilepton searches at the Tevatron. The trilepton
rate has been calculated for those points in parameter space which satisfy not
only the minimal theoretical and experimental LEP constraints, but also the
{\em combined} effect of the following indirect experimental constraints: (i)
the CLEO limits on the $b\to s\gamma$ rate, (ii) the long-standing limit on the
anomalous magnetic moment of the muon, (iii) the non-observation of anomalous
muon fluxes in underground detectors (``neutrino telescopes"), and (iv) the
electroweak LEP high-precision measurements in the form of the
$\epsilon_{1},\epsilon_b$ parameters. For $m_t=150\GeV$, the trilepton
constraint rules out some regions of parameter space with chargino masses as
high as $m_{\chi^\pm_1}\approx105\GeV$, although it is not possible to
establish a new absolute lower bound on the chargino mass. For $m_t=170\GeV$,
the simultaneous imposition of {\em all} of the above constraints excludes the
dilaton scenario completely, and leaves only a few allowed points in parameter
space in the no-scale scenario (with $m_{\tilde q}\approx m_{\tilde
g}\lsim285\GeV$). The five-fold increase in integrated luminosity expected in
the upcoming Tevatron run should probe some regions of parameter space with
chargino masses much beyond the reach of LEPII.


title: Equivalence Theorem and Dynamical Symmetry Breaking:

abstract:
  The equivalence theorem, between the longitudinal gauge bosons and the states
eaten up by them in the process of symmetry breaking, is shown to be valid in a
class of models where the details of dynamical symmetry breaking makes it
obscure.


title: BARYOGENESIS. byvited talk at TAUP 93, LNGS, Italy, September 1993

abstract:
  A review of the present state of the baryogenesis is given with an emphasis
on electroweak baryogenesis. Technical details of the numerous models cosidered
in the literature are not elaborated but unresolved problems of the issue are
considered. Different logically possible alternatives of the electroweak
scenarios are presented. A possible impact of bariogenesis on the universe
structure formation is discussed.


title:
General relations of heavy quark-antiquark potentials induced by
  reparameterization invariance

abstract:
  A set of general relations between the spin-independent and spin-dependent
potentials of heavy quark and anti-quark interactions are derived from
reparameterization invariance in the Heavy Quark Effective Theory. It covers
the Gromes relation and includes some new interesting relations which are
useful in understanding the spin-independent and spin-dependent relativistic
corrections to the leading order nonrelativistic potential.


title:
Tracing CP violation in the production of top quark pairs by multiple
  TeV proton-proton collisions

abstract:
  We investigate the possibilities of searching for non-standard CP violation
in $pp\to t\bar{t}X$ at multiple TeV collision energies. A general kinematic
analysis of the underlying partonic production processes $gg\to t\bar{t}$ and
$q\bar{q}\to t\bar{t}$ in terms of their density matrices is given. We evaluate
the CP-violating parts of these matrices in two-Higgs doublet extensions of the
standard model (SM) and give results for CP asymmetries at the parton level. We
show that these asymmetries can be traced by measuring suitable observables
constructed from energies and momenta of the decay products of $t$ and $\bar{t}
$. We find CP-violating effects to be of the order of $10^{-3}$ and show that
possible contaminations induced by SM interactions are savely below the
expected signals.


title: Future Solar Neutrino Experiments and Neutrino Spin-Flavour Precession

abstract:
  The main features of the observables in the SNO and Super-Kamiokande solar
neutrino experiments in the case of neutrino spin and/or spin-flavour
precession in the magnetic field of the sun are discussed. It is shown without
any model dependent assumption that in the case of Majorana transition magnetic
moments the NC event rate $N^{\mathrm{NC}}$ does not depend on time and a
measurement of $N^{\mathrm{NC}}$ will allow to determine the initial flux of
$^8\mathrm{B}$ neutrinos with a theoretical uncertainty of a few \%. In the
case of Dirac magnetic moments the NC event rate will depend on time and we
obtain a model independent lower bound for the transition probability of
initial $\nu_e$'s into right-handed sterile neutrinos.


title: Unstable particles in One Loop Calculations

abstract:
  We present a gauge invariant way to compute one loop corrections to processes
involving the production and decay of unstable particles.


title: Production and Decay of Scalar Stoponium Bound States

abstract:
  In this paper we discuss possible signatures for the production of scalar
\stst\ (stoponium) bound states \sigst\ at hadron colliders, where \st\ is the
lighter scalar top eigenstate. We first study the decay of \sigst; explicit
expressions are given for all potentially important decay modes. If \st\ has
unsuppressed two--body decays, they will always overwhelm the annihilation
decays of \sigst. Among the latter, we find that usually either the $gg$ or
$hh$ final state dominates, depending on the size of the off--diagonal entry of
the stop mass matrix; $h$ is the lighter neutral scalar Higgs boson of the
minimal supersymmetric model. If \msig\ happens to be close to the mass of one
of the neutral scalar Higgs bosons, $Q \bar{Q}$ final states dominate ($Q=b$ or
$t$). \ww\ and $ZZ$ final states are subdominant. We argue that $\sigst
\rightarrow \gamgam$ decays offer the best signal for stoponium production at
hadron colliders. The tevatron should be able to close the light stop window
left open by LEP searches, but its mass reach is limited to $\msig \leq 90$
GeV. In contrast, at the LHC one should ultimately be able to probe the region
$\msig \leq 700$ GeV, if the $hh$ partial width is not too large. We also
comment on the feasibility of searching for \sigst\ production at hadron
colliders in the $ZZ, \ Z \gamma$ and \fourtau\ final states, and briefly
mention \sigst\ production at \gamgam\ colliders.


title: Light Fermion Masses in Superstring Derived Standard--like Models

abstract:
  I discuss the suppression of the lightest generation fermion mass terms in
realistic superstring standard--like models in the free fermionic formulation.
The suppression of the mass terms is a consequence of horizontal symmetries
that arise due to the $Z_2\times Z_2$ orbifold compactification. In a specific
model I investigate the possibility of resolving the strong CP puzzle by a
highly suppressed up quark mass. In some scenarios the up quark mass may be as
small as $10^{-8}MeV$. I show that in the specific model the suppression of the
up quark mass is incompatible with the requirement of a nonvanishing electron
mass. I discuss how this situation may be remedied.


title: Standard Model CP-violation and Baryon asymmetry

abstract:
  Simply based on CP arguments, we argue against a Standard Model explanation
of the baryon asymmetry of the universe in the presence of a first order phase
transition. A CP-asymmetry is found in the reflection coefficients of quarks
hitting the phase boundary created during the electroweak transition. The
problem is analyzed both in an academic zero temperature case and in the
realistic finite temperature one. The building blocks are similar in both
cases: Kobayashi-Maskawa CP-violation, CP-even phases in the reflection
coefficients of quarks, and physical transitions due to fermion self-energies.
In both cases an effect is present at order $\alpha_W^2$ in rate. A standard
GIM behaviour is found as intuitively expected. In the finite temperature case,
a crucial role is played by the damping rate of quasi-particles in a hot
plasma, which is a relevant scale together with $M_W$ and the temperature. The
effect is many orders of magnitude below what observation requires, and
indicates that non standard physics is indeed needed in the cosmological
scenario.


title: Weak $\Lam N\to NN$ Transition in the Direct Quark Mechanism

abstract:
  The weak $\Lam N\to NN$ transition is studied in the valence quark model
approach. The momentum transfer for this transition is so large that the
short-distance two baryon dynamics must be taken into account. The two baryon
system is described in the quark cluster model and the weak transition
amplitude is calculated by evaluating the matrix elements of the effective weak
$\Delta S= 1$ hamiltonian. The results indicate some qualitative differences
when compared with those in conventional meson-exchange calculations.
Especially, we conclude that contributions of the $\Delta I={3\over2}$
transition are significant and that the discrepancy in the $n-p$ ratio between
theory and experiment could be resolved by including the direct-quark
processes.


title: Lepton Flavor Non-Conservation

abstract:
  In the present work we review the most prominent lepton flavor violating
processes ($\mu \ra e\gamma$, $\mu \ra 3e$, $(\mu , e)$ conversion, $M-\bar M$
oscillations etc), in the context of unified gauge theories. Many currently
fashionable extensions of the standard model are considered, such as: {\it i)}
extensions of the fermion sector (right-handed neutrino); {\it ii)} minimal
extensions involving additional Higgs scalars (more than one isodoublets,
singly and doubly charged isosinglets, isotriplets with doubly charged members
etc.); {\it iii)} supersymmetric or superstring inspired unified models
emphasizing the implications of the renormalization group equations in the
leptonic sector. Special attention is given to the experimentaly most
interesting $(\mu - e)$ conversion in the presence of nuclei. The relevant
nuclear aspects of the amplitudes are discussed in a number of fashionable
nuclear models. The main features of the relevant experiments are also
discussed, and detailed predictions of the above models are compared to the
present experimental limits.


title:
Supersymmetry Relations Between Contributions To One-Loop Gauge Boson
  Amplitudes

abstract:
  We apply ideas motivated by string theory to improve the calculational
efficiency of one-loop weak interaction processes with massive external gauge
bosons. In certain cases ``supersymmetry'' relations between diagrams with a
fermion loop and with a gauge boson loop hold. This is explicitly illustrated
for a particular one-loop standard model process with four-external gauge
bosons. The supersymmetry relations can be used to provide further significant
improvements in calculational efficiency.


title: Electric Polarizability of the Nucleon in the Nambu--Jona-Lasinio Model

abstract:
  The electric polarizability of the nucleon is calculated in the soliton
approach to the Nambu--Jona-Lasinio model. We analyze the leading-$N_c$
contributions, as well as the effects of rotational $1/N_c$ corrections and
$\Delta$-$N$ mass splitting. Our model prediction is substantially reduced
compared to other soliton calculations, and is closer to the experimental
value.


title: Inclusive Semileptonic Decays in QCD Including Lepton Mass Effects

abstract:
  Starting from an Operator Product Expansion in the Heavy Quark Effective
Theory up to order 1/m_b^2 we calculate the inclusive semileptonic decays of
unpolarized bottom hadrons including lepton mass effects. We calculate the
differential decay spectra d\Gamma/(dE_\tau ), and the total decay rate for B
meson decays to final states containing a \tau lepton.


title: The $\epsilon$-expansion and the electroweak phase transition

abstract:
  Standard perturbative (or mean field theory) techniques are not adequate for
studying the finite-temperature electroweak phase transition in some cases of
interest to scenarios for electroweak baryogenesis. We instead study the
properties of this transition using the renormalization group and the
$\epsilon$-expansion. This expansion, based on dimensional continuation from 3
to $4{-}\epsilon$ spatial dimensions, provides a systematic approximation for
computing the effects of (near)-critical fluctuations. The $\epsilon$-expansion
is known to predict a first-order transition in Higgs theories, even for heavy
Higgs boson masses. The validity of this conclusion in the standard model is
examined in detail. A variety of physical quantities are computed at leading
and next-to-leading order in $\epsilon$. For moderately light Higgs masses
(below 100~GeV), the $\epsilon$-expansion suggests that the transition is more
strongly first order than is predicted by the conventional analysis based on
the one-loop (ring-improved) effective potential. Nevertheless, the rate of
baryon non-conservation after the transition is found to be {\em larger\/} than
that given by the one-loop effective potential calculation. Detailed
next-to-leading order calculations of some sample quantities suggests that the
$\eps$-expansion is reasonably well behaved for Higgs masses below 100--200
GeV. We also compare the $\eps$-expansion with large-$N$ results (where $N$ is
the number of scalar fields) and find that the $\eps$-expansion is less well
behaved in this limit.


title: Grand Unification of Fermion Masses

abstract:
  After a brief review of the flavour problem we present a new predictive
framework based on SUSY $SO(10)$ theory, where the first family plays a role of
the mass unification point. The inter-family hierarchy is first generated in a
sector of superheavy fermions and then transfered in an inverse way to ordinary
quarks and leptons by means of the universal seesaw mechanism. The obtained
mass matrices are simply parametrized by two small coefficients which can be
given by the ratio of the GUT and superstring compactification scales. The
model allows a natural (without fine tuning) doublet-triplet splitting. It has
a strong predictive power, though no special texture is utilized in contrast to
the known predictive frameworks. Namely, the model implies that $m_b=4-5$ GeV,
$m_s=100-150$ MeV, $m_u/m_d=0.5-0.7$ and $\tan\beta<1.1$. The Top quark is
naturally in the 100 GeV range, but not too heavy: $m_t<150$ GeV. All CKM
mixing angles are in correct range. The Higgsino mediated $d=5$ operators for
the proton decay are naturally suppressed. {On the basis of talks given at the
XVI International Warsaw Meeting on Elementary Particle Physics "New Physics
with New Experiments", Kazimierz, Poland, 24-28 May 1993, and at the II Gran
Sasso Summer Institute "From Particle Physics to Cosmology", Gran Sasso
National Laboratory, Italy, 6-17 September 1993.}


title: Tensor Integrals for Two Loop Standard Model Calculations

abstract:
  We give a new method for the reduction of tensor integrals to finite integral
representations and UV divergent analytic expressions. This includes a new
method for the handling of the gamma-algebra. TYPO IN EQUATION (5) CORRECTED,
MACROS REORDERED.


title:
$1/m_b$ Corrections in the ACCMM Model for Inclusive Semileptonic B
  Decay

abstract:
  We re-examine the model of Altarelli, Cabibbo, Corb\`{o}, Maiani and
Martinelli for inclusive semileptonic B decay, in the light of recent
calculations in heavy quark effective theory. The model can be shown to have
no~$1/m_b$ corrections, with a suitable definition of the b quark mass~$m_b$.
However, we find that the structure of the $1/m_b^2$~terms is incompatible with
the predictions of heavy quark effective theory. The numerical significance of
this discrepancy is discussed.


title: Heavy meson effective thoery with 1/M_Q correction

abstract:
  We construct an effective Lagrangian of heavy and light mesons with $1/M_Q$
correction. The Lagrangian is constructed model independent way by using only
the information of the symmetry of QCD. Reparameterisation invariance at the
meson level is taken into account for the consistency of the theory. The
partial decay width of the process $D^{*+} \rightarrow D^0 \pi^+$ and the form
factors of the process ${\bar B}^0 \rightarrow \pi^+ l {\bar \nu}$ are
calculated with the $1/M_Q$ correction. We also introduce the light vector
mesons based on the approach of the hidden local symmetry. The form factors of
the process ${\bar B}^0 \rightarrow \rho^+ l {\bar \nu}$ are calculated with
thus introduced $\rho$-meson. These results are easily translated to the
$D$-meson semileptonic decays.


title:
Real-Time Thermal Propagators and the QED Effective Action for an
  External Magnetic Field

abstract:
  The thermal averaged real-time propagator of a Dirac fermion in a static
uniform magnetic field $B$ is derived. At non-zero chemical potential and
temperature we find explicitly the effective action for the magnetic field,
which is shown to be closely related to the Helmholz free energy of a
relativistic fermion gas, and it exhibits the expected de\ Haas -- van\ Alphen
oscillations. An effective QED coupling constant at finite temperature and
density is derived, and compared with renormalization group results. We discuss
some astrophysical implications of our results.


title: Heavy Quark S- to P-Wave Transitions in a Consistent Quark Model

abstract:
  In Heavy Quark Effective Theory the calculation of form-factors of higher
excited states in a non-relativistic framework suffers severe inconsistencies
due to frame dependencies. We show how careful inclusion of the Wigner-rotation
of the spin of the light quark and a covariant description of the meson
wave-function resolves these inconsistencies. We match this onto HQET and
compute the relevant form factors $\xi_{1/2}$ and $\xi_{3/2}$ to order $v^2$.


title: Photon-Photon Scattering at the Photon Linear Collider

abstract:
  Photon-photon scattering at the Photon Linear Collider is considered.
Explicit formulas for helicity amplitudes due to $W$ boson loops are presented.
It is shown that photon-photon scattering should be easily observable at PLC
and separation of the $W$ loop contribution (which dominates at high energies)
will be possible at $e^+e^-$ c.m. energy of 500~GeV or higher.


title:
The Semileptonic Decay Fraction of B Mesons in the Light of Interfering
  Amplitudes

abstract:
  Consequences of the interference between spectator amplitudes for the
lifetimes and semileptonic decay fractions of B^0 and B^+ mesons are discussed.
Assuming duality and constructive interference between spectator amplitudes we
are able to explain the low experimental value for the semileptonic decay
fraction of $B$ mesons. Extracting these amplitudes from a fit to 11 exclusive
hadronic B decay fractions we find
  a_1 = 1.05 +/- 0.03 +/- 0.10,
  a_2 =+0.227 +/ 0.012 +/- 0.022,
  an inclusive semileptonic decay fraction of
  (11.2 +/- 0.5 +/- 1.7),
  and a lifetime ratio
  tau(B^+) / tau(B^0) = 0.83 +/- 0.01 +/- 0.01.


title: Partial Derivation of Transformation Properties of Quarks and Leptons

abstract:
  Under the assumptions that $SU(3)_c\times U(1)_Y \times G^{\prime}$ with
$G^{\prime}$ simple is a local symmetry group at high energies, that color is
parity-conserving, and the Y-charges are irreducible, we show that anomaly
constraints imply the minimal set of fermions is fifteen in number. Given this
minimal set, we further show that $G^{\prime}$ must be $SU(2)$ and the unbroken
gauge symmetry is {\it either} color {\it or} the product of color with
electric charge.


title: Electroweak Radiative Corrections

abstract:
  A new framework to study electroweak physics at one-loop level in general
${\rm SU(2)_L \times U(1)_Y}$ theories is introduced. It separates the 1-loop
corrections into two pieces: process specific ones from vertex and box
contributions and the universal ones due to contributions to the gauge boson
propagators. The latter are parametrized in terms of four effective form
factors, $\bar{e}^2(q^2)$, $\bar{s}^2(q^2)$, $\bar{g}_Z^2(q^2)$, and
$\bar{g}_W^2(q^2)$, correspondingly to $\gamma\gamma$, $\gamma Z$, $ZZ$, and
$WW$ propagators. By assuming only the standard model contributions to the
process specific corrections, the magnitudes of the four form factors are
determined at $q^2=0$ and at $q^2=m_Z^2$ from all available precision
experiments. These values are then compared systematically with the predictions
of the ${\rm SU(2)_L \times U(1)_Y}$ theories. No deviation from the standard
model has been identified. Plausible range of the top quark mass is then
obtained for a given Higgs boson mass and $\alpha_s$ .


title: Natural Conservation of R Parity in Supersymmetry

abstract:
  Since baryon number B and lepton number L are no longer automatically
conserved once the standard model is extended to include supersymmetry, the
usually assumed conservation of R parity is an imposed condition. For a more
satisfactory realization of supersymmetry, we propose here a new model which
conserves R automatically. It is unifiable under SO(14) and has exotic fermions
at the 100 GeV scale. One important result is the enhancement of the
Higgs-boson decay rates into two gluons and into two photons by factors of 25
and 15 respectively.


title: Direct CP violation in b -> d J/\psi decays

abstract:
  We investigate the possibility of observing direct CP violation in
self-tagging B-meson decays of the type b -> d J/\psi. The CP asymmetry can be
generated due to strong or electromagnetic scattering in the final state, or
due to long distance effects. The first two contributions give asymmetries of a
few 10^(-3), in the standard model. The long distance effects are hard to
estimate, but it cannot be excluded that they yield asymmetries of about 1%.


title: Cancellation of power enhancements in non-spectator decays

abstract:
  Exclusive non-spectator decay rates of beauty hadrons contain power
enhancements of the form (m_b/m)^2 and m_b/m, where m_b is the b-quark mass and
m is a light quark mass. An implicit argument has been recently given according
to which these singularities cancel in the totally inclusive decay width. We
present in this note a completely explicit computation of the diagrams
containing power enhancements. Our results agree with the previous general
conclusion.


title: Supersymmetric Left-Right Model and its Tests in Linear Colliders

abstract:
  We investigate phenomenological implications of a supersymmetric left-right
model based on $SU(2)_L\times SU(2)_R\times U(1)_{B-L}\,$ gauge symmetry
testable in the next generation linear colliders. We concentrate in particular
on the doubly charged $SU(2)_R$ triplet higgsino $\tilde\Delta$, which we find
very suitable for experimental search. We estimate its production rate in
$e^+e^-$, $e^-e^-$, $e^-\gamma$ and $\gamma\gamma$ collisions and consider its
subsequent decays. These processes have a clear discovery signature with a very
low background from other processes.


title: A New Approach to Numerical Quantum Field Theory

abstract:
  In this note we present a new numerical method for solving Lattice Quantum
Field Theory. This Source Galerkin Method is fundamentally different in concept
and application from Monte Carlo based methods which have been the primary mode
of numerical solution in Quantum Field Theory. Source Galerkin is not
probabilistic and treats fermions and bosons in an equivalent manner.


title:
Improved QCD sum rule estimates of the higher twist contributions to
  polarised and unpolarised nucleon structure functions

abstract:
  We re-examine the estimates of the higher twist contributions to the integral
of $g_1$, the polarised structure function of the nucleon, based on QCD sum
rules. By including corrections both to the perturbative contribution and to
the low energy contribution we find that the matrix elements of the relevant
operators are more stable to variations of the Borel parameter $M^2$, allowing
for a meaningful estimate of the matrix elements. We find that these matrix
elements are typically twice as large as previous estimates. However, inserting
these new estimates into the recently corrected expressions for the first
moments of $g_1$ leads to corrections too small to affect the phenomenological
analysis. For the unpolarised case the higher twist corrections to the GLS and
Bjorken sum rules are substantial and bring the estimate of $\Lambda_{QCD}$
from the former into good agreement with that obtained from the $Q^2$
dependence of deep inelastic data.


title: How Big Can Anomalous W Couplings Be?

abstract:
  Conventional wisdom has it that anomalous gauge-boson self-couplings can be
at most a percent or so in size. We test this wisdom by computing these
couplings at one loop in a generic renormalizable model of new physics. (For
technical reasons we consider the CP-violating couplings here, but our results
apply more generally.) By surveying the parameter space we find that the
largest couplings (several percent) are obtained when the new particles are at
the weak scale. For heavy new physics we compare our findings with expectations
based on an effective-lagrangian analysis. We find general patterns of induced
couplings which robustly reflect the nature of the underlying physics. We build
representative models for which the new physics could be first detected in the
anomalous gauge couplings.


title:
Higher-Order Corrections to the Large-$N_c$ Bound on
  $M_{\eta}/M_{\eta'}$

abstract:
  Next-to-leading $1/\N$ corrections to the upper bound on $M_{\eta}/M_{\eta
'}$ recently obtained by Georgi are considered. These corrections are just what
is needed to reconcile the bound with the observed $\eta$ and $\eta'$ masses.


title: Lattice Phenomenology

abstract:
  A review of the status of lattice simulations in particle physics
phenomenology is presented. Recent computations of leptonic decay constants of
light and heavy mesons, and of the Isgur-Wise function relevant for
semi-leptonic decays of $B$-mesons, are discussed in some detail. Calculations
of other quantities are briefly outlined. The systematic errors inherent in
lattice simulations, and procedures to reduce and control them, are described.


title: The Isgur-Wise Function from the Lattice

abstract:
  We calculate the Isgur-Wise function by measuring the elastic scattering
amplitude of a $D$ meson in the quenched approximation on a $24^3\times48$
lattice at $\beta=6.2$, using an $O(a)$-improved fermion action. We use this
result, in conjunction with heavy-quark symmetry, to extract $|V_{cb}|$ from
the experimentally measured $\bar B\to D^*l\bar\nu\,$\ differential decay
width.


title: Instanton-induced particle production in deep inelastic scattering

abstract:
  I discuss the instanton-induced contributions to the coefficient functions in
front of parton densities. They correspond to the spherically symmetric
particle production at the level of $10^{-2}-10^{-5}$ of the total cross
section of deep inelastic scattering from the parton.


title: Pion Loop Contribution to the Electromagnetic Pion Charge Radius

abstract:
  A phenomenological Dyson-Schwinger equation approach to QCD, formalised in
terms of a QCD based model field theory, is used to calculate the
electromagnetic charge radius of the pion. The contributions from the quark
core and pion loop, as defined in this approach, are identified and compared.
It is shown explicitly that the divergence of the charge radius in the chiral
limit is due to the pion loop and that, at the physical value of the pion mass,
this loop contributes less than 15\% to $\langle r^2_\pi\rangle$; i.e. the
quark core is the dominant determining characteristic for the pion. This
suggests that quark based models which fail to reproduce the $\ln\,m_\pi$
divergence of $\langle r^2_\pi\rangle$ may nevertheless incorporate the
dominant characteristic of the pion: its quark core.


title:
The Behavior of the Slope of Elastic Nucleon Scattering at Small
  Transfer Momenta and Recent Ua4 Data

abstract:
  Theoretical predictions for the behavior of the slope of the nucleon-nucleon
scattering and another parameters of the differential cross sections in the
framework of the dynamic model are compared with the recent UA4 data at small
transfer momenta and at the centre-of-mass energy of 541 GeV. The predictions
at superhigh energies are considered.


title: Weinberg-Type Sum Rules at Zero and Finite Temperature

abstract:
  We consider sum rules of the Weinberg type at zero and nonzero temperatures.
On the basis of the operator product expansion at zero temperature we obtain a
new sum rule which involves the average of a four-quark operator on one side
and experimentally measured spectral densities on the other. We further
generalize the sum rules to finite temperature. These involve transverse and
longitudinal spectral densities at each value of the momentum. Various
scenarios for the relation between chiral symmetry restoration and these finite
temperature sum rules are discussed.


title: The Hill Theorem

abstract:
  It is studied how strong interactions in the Higgs sector can lead to
deviations in vector boson selfcouplings. Normally such effects are small due
to Veltman's screening theorem. It is shown that strong interactions are
possible, if there is a hierarchy of strong interactions in the Higgs sector.
This is called Hill's theorem.


title: A Type II Supernovae Constraint on $\nu_e$-$\nu_s$

abstract:
  The role of a resonant $\nu_e$-$\nu_s$ oscillation is discussed in the event
of a supernova explosion. It is concluded that a significant $\nu_e$-$\nu_s$
mixing may hinder the ability of the supernova to explode. It may also cool the
proto-neutron star too quickly with respect to the observed cooling time of
several seconds. The constraints on the $\nu_e$-$\nu_s$ mixing parameters based
on the above arguments are calculated.


title:
Radiative Corrections to Neutralino and Chargino Masses in the Minimal
  Supersymmetric Model

abstract:
  We determine the neutralino and chargino masses in the MSSM at one-loop. We
perform a Feynman diagram calculation in the on-shell renormalization scheme,
including quark/squark and lepton/slepton loops. We find generically the
corrections are of order 6%. For a 20 GeV neutralino the corrections can be
larger than 20%. The corrections change the region of $\mu,\ M_2,\ \tan\beta$
parameter space which is ruled out by LEP data. We demonstrate that, e.g., for
a given $\mu$ and $\tan\beta$ the lower limit on the parameter $M_2$ can shift
by 20 GeV.


title: QCD corrections to decays of polarised charm and bottom quarks

abstract:
  Distributions of charged leptons in semileptonic $\Lambda_c$ and $\Lambda_b$
decays can be used as spin analysers for the corresponding charm and bottom
quarks. QCD corrections to the energy spectra of charged leptons have been
given in the literature as well as the corrections to the angular dependence
for polarised up-type quarks. The analogous formulae are derived also for
polarised down-type quarks. These results are applied to the decays of
polarised charm and bottom quarks. The corrections to the asymmetries are found
to be small for charm decays. For bottom decays they exhibit a non-trivial
dependence on the energy of the charged lepton.


title: Heavy quark supermultiplet excitations

abstract:
  Lorentz covariant wave functions for meson and baryon supermultiplets are
simply derived by boosting $SU(2)_J$ representations corresponding to
multiquark systems at rest.


title:
One loop corrections to the Neutralino sector and Radiative Electroweak
  Breaking in the MSSM

abstract:
  We compute one loop radiative corrections to the physical neutralino masses
in the MSSM considering the dominant top-stop contributions. We present a
numerical renormalization group analysis of the feasibility of the radiative
gauge symmetry breaking parametrized by the standard soft supersymmetry
breaking terms. Although the above computed effects can be in principle large
for extreme values of the Yukawa couplings, they do not in general exceed a few
per cent for most of the parameter space. Therefore tree level constraints
imposed on the gluino mass $m_{\tilde{g}}$ and on the superpotential parameter
$\mu$ by LEP1 and CDF experiments, are not upset by the heavy top-stop sector.


title:
Chiral Symmetry Restoration at Finite Temperature in the Linear
  Sigma--Model

abstract:
  The temperature behaviour of meson condensates $<\sigma_0>$ and $<\sigma_8>$
is calculated in the $SU(3)\times SU(3)$-linear sigma model. The couplings of
the Lagrangian are fitted to the physical $\pi,K,\eta,\eta'$ masses, the pion
decay constant and a $O^+(I=0)$ scalar mass of $m_\sigma=1.5$ GeV. The quartic
terms of the mesonic interaction are converted to a quadratic term with the
help of a Hubbard-Stratonovich transformation. Effective mass terms are
generated this way, which are treated self-consistently to leading order of a
$1/N$-expansion. We calculate the light $<\bar q q>$ and strange $<\bar s
s>$-quark condensates using PCAC relations between the meson masses and
condensates. For a cut-off value of 1.5 GeV we find a first-order chiral
transition at a critical temperature $T_c\sim 161$ MeV. At this temperature the
spontaneously broken subgroup $SU(2)\times SU(2)$ is restored. Entropy density,
energy density and pressure are calculated for temperatures up to and slightly
above the critical temperature. To our surprise we find some indications for a
reduced contribution from strange mesons for $T\geq T_c$.


title:
Right-handed-neutrino Majorana mass at the SUSY GUT scale and the
  solution of the solar-neutrino problem

abstract:
  In the SUSY GUT scenario, it is natural to assume the right-handed-neutrino
Majorana-mass scale to be $10^{16}$ GeV. This will in principle lead, by the
seesaw mechanism, to a $ \nu_{\tau} $ mass of order $ m_t^2 / (10^{16}\, {\rm
GeV}) \sim 3 \times 10^{-3}\, {\rm eV} $. This suggests that the solution of
the solar-neutrino puzzle should be either the MSW effect in
$\nu_e$--$\nu_{\tau}$ oscillations, with $ m_{\nu_{\tau}}^2 \sim 10^{-5}\, {\rm
eV}^2 $, or long-wavelength $\nu_e$--$\nu_{\mu}$ oscillations, with $
m_{\nu_{\mu}}^2 \sim 10^{-10}\, {\rm eV}^2 $. These solutions require
unexpectedly large mixings of $ \nu_e $ with $ \nu_{\tau} $ and $ \nu_{\mu} $,
respectively. I suggest a variation of the Dimopoulos--Hall--Raby model for the
fermion mass matrices which can accomodate such large mixings.


title: A Texture Bestiary

abstract:
  Textures are topologically nontrivial field configurations which can exist in
a field theory in which a global symmetry group $G$ is broken to a subgroup
$H$, if the third homotopy group $\p3$ of $G/H$ is nontrivial. We compute this
group for a variety of choices of $G$ and $H$, revealing what symmetry breaking
patterns can lead to texture. We also comment on the construction of texture
configurations in the different models.


title: The Goldberger -- Treiman Relation, $g_A$ and $g_{\pi NN}$ at $T\neq 0$

abstract:
  The Goldberger-Treiman relation is shown to persist in the chiral limit at
finite temperatures to order $O(T^2)$. The $T$ dependence of $g_A$ turns out to
be the same as for $F_{\pi}$, $g_{A}(T)=g_{A}(0)(1-T^2/12F^2)$, while $g_{\pi
NN}$ is temperature independent to this order. The baryon octet ${\cal D}$ and
${\cal F}$ couplings also behave as $F_{\pi}$ if only pions are massless in the
pseudoscalar meson octet.


title: Electromagnetic Deflection of Spinning Particles

abstract:
  We show that it is possible to obtain self-consistent and physically
acceptable relativistic classical equations of motion for a point-like
spin-half particle possessing an electric charge and a magnetic dipole moment,
directly from a manifestly covariant Lagrangian, if the classical degrees of
freedom are appropriately chosen. It is shown that the equations obtained
encompass the well-tested Lorentz force and Thomas--Bargmann--Michel--Telegdi
spin equations, as well as providing a definite specification of the classical
_magnetic_dipole_ force_, whose exact form has been the subject of recent
debate. Radiation reaction---the force and torque on an accelerated particle
due to its self-interaction---is neglected at this stage.


title: The ACCMM Model and the Heavy Quark Expansion

abstract:
  The ACCMM model predicts the lepton spectrum from $B$ meson decay by assuming
the meson disintegrates into a spectator quark of definite mass and momentum
distribution and an off shell $b$ quark whose decay leptons (boosted into the
rest frame of the meson) determine the lepton spectrum. In this letter, we show
that one can define a model dependent $b$ quark mass so that the spectrum
derived from the ACCMM model agrees very well with the free quark decay
spectrum far from the endpoint. Near the endpoint, there is some disagreement,
indicating the result is more model dependent. The integrated spectra are
however very nearly identical. These results are in accordance with
expectations based on the heavy quark effective theory. The detailed analytic
study of this model helps elucidate the HQET result, and in particular the
meaning of the $b$ quark mass. We conclude that for LEP experiments, free quark
decay might be as general and more simple than the ACCMM ansatz for modeling
the inclusive charged lepton spectrum from $B$ meson decay.


title:
Dependence of the Form Factors of $B \to \pi \ell \nu$ on the Heavy
  Quark Mass

abstract:
  We use QCD sum rules to analyze the semileptonic transition $B \to \pi \ell
\nu$ in the limit $m_b \to \infty$. We derive the dependence of the form factor
$F_1(0)$ on the heavy quark mass, which is compatible with the expected
dependence for the simple pole model of $F_1(q^2)$.


title: Quantum statistical effects on parton distribution scaling behaviour

abstract:
  Starting from the old idea that Fermi statistics for quarks play a
fundamental role to explain some features of hadron structure, we study the
modification of the scaling behaviour of parton distributions due to quantum
statistical effects. In particular, by following an interesting formal analogy
which holds between the Altarelli-Parisi evolution equations, in leading-log
approximation, and a set of Boltzmann equations, we generalize the evolution
equations to take into account Pauli exclusion principle and gluon induced
emission.


title: The Regularization of the Fermion Determinant in Chiral Quark Models

abstract:
  The momentum dependence of the quark self energy gives a physically motivated
and consistent regularization of both the real and imaginary parts of the quark
loop contribution to the meson action. We show that the amplitudes for
anomalous processes are always reproduced correctly.


title: Veneziano Ghost Versus Isospin Breaking

abstract:
  It is argued that an account for the Veneziano ghost pole, appearing in
resolving the U(1) problem, is necessary for understanding an isospin violation
in the $ \pi - \eta - \eta' $ system. By virtue of a perturbative expansion
around the $ SU(2)_{V} $ ( $ m_{u} = m_{d} $ ) symmetric Veneziano solution, we
find that the ghost considerably suppresses isospin breaking gluon and s-quark
matrix elements. We speculate further on a few cases where the proposed
mechanism can play an essential role. We discuss the isospin violation in
meson-nucleon couplings and its relevance to the problem of charge asymmetric
nuclear forces and possible breaking of the Bjorken sum rule. It is shown that
the ghost pole could yield the isospin violation of order 2 \% for the $ \pi N
$ couplings and 20 \% for the
  Bjorken sum rule.


title:
Determination of Vts from D -> K* l nu and B -> K* gamma data via heavy
  quark symmetry and perturbative QCD

abstract:
  We use heavy quark effective theory (HQET) and perturbative QCD to study the
heavy meson -- light vector meson transitions involved in D and B decays. HQET
is used to relate the measured D -> K* l nu vector and axial-vector form
factors at four-momentum transfer q^2 = 0 to the B -> K* gamma tensor and
axial-tensor form factors at q^2 = 16.5 GeV^2. Perturbative QCD is then used to
find matching conditions for the B-meson form factors at q^2 = 0. A five
parameter ``vector dominance'' type fit of the two HQET form factors,
consisting of single pole, double pole, and subtraction terms, is used to match
the data at q^2 = 16.5 GeV^2 to QCD at q^2 = 0. The values at q^2 = 0 are
compared with recent data on the exclusive rate for B -> K* gamma decay to
extract a value for the Cabibbo-Kobayashi-Maskawa matrix element Vts = 0.035,
with 28% experimental uncertainty, and 32% theoretical uncertainty from higher
order QCD effects and violations of heavy quark symmetry.


title:
TeV Scale Leptoquarks as a Signature of Standard--like Superstring
  Models

abstract:
  We show that there can be TeV scale scalar and fermionic leptoquarks with
very weak Yukawa couplings in a generic standard--like superstring model.
Leptoquark--(down--like) quark mixing though present, is not large enough to
violate the unitarity bounds on the CKM matrix. The constraints on leptoquark
masses and couplings from FCNCs are easily satisfied whereas those from baryon
number violation may cause problems. The leptoquarks of the model are compared
to the ones in $E_6$ Calabi--Yau and flipped $SU(5) \times U(1)$ models.


title:
The connection between single transverse spin asymmetries and the second
  moment of $g_2$

abstract:
  We point out that the size of the photon single spin asymmetry in
high--energy proton proton collisions with one transversely polarized proton
can be related to $d^{(2)}$, the twist three contribution to the second moment
of $g_2$. Both quantities should be measured in the near future. The first was
analysed by Qiu and Sterman, the second was estimated by Balitsky, Braun, and
Kolesnichenko. Both experiments measure effectively the strength of the
collective gluon field in the nucleon oriented relative to the nucleon spin.
The sum rule results suggest that the single spin asymmetry is rather small for
the proton, but could be substantial for the neutron.


title: On the Non-Equilibrium Early Universe

abstract:
  We study non--equilibrium ensemble corrections to particle masses and the
effective potential in the early universe, using a uniform momentum
distribution as an example. The resulting thermalization temperature is
computed assuming \sm degrees of freedom, and it is always found to be below
$5\times 10^{14}$ GeV, implying that GUT phase transitions typically take place
out of equilibrium. For the abelian Higgs model we find that the phase
transition is of second order if it occurs before equilibration, in contrast to
the first order equilibrium phase transition.


title: The Relevance of the Dipole Penguin Operators in $\epsilon'/\epsilon$

abstract:
  The standard model contribution to $\epsilon'/\epsilon$ of the magnetic- and
electric-dipole penguin operators $Q_{11} = \frac{g_s}{16\pi^2} \, m_s \:
\bar{s}\, \sigma_{\mu\nu} t^a G^{\mu\nu}_a (1-\gamma_5 )\, d $ and $Q_{12} =
\frac{eQ_d}{16\pi^2}\, m_s \: \bar{s}\, \sigma_{\mu\nu}
  F^{\mu\nu} (1-\gamma_5 )\, d $ is discussed. While the electromagnetic
penguin $Q_{12}$ seems to have a vanishingly small matrix element, we find that
the gluonic dipole operator $Q_{11}$ may give a contribution to
$\epsilon'/\epsilon$ comparable to that of other operators so far considered,
and should therefore be consistently included in the analysis.


title: Isgur-Wise Function from Bethe-Salpeter Amplitude

abstract:
  We develop the improved ladder approximation to QCD in order to apply it to
the heavy quark mesons. The resulting Bethe-Salpeter equation is expanded in
powers of the inverse heavy quark mass 1/M, and is shown to be consistent with
the heavy quark spin symmetry. We calculate numerically the universal leading
order BS amplitude for heavy pseudoscalar and vector mesons, and use this to
evaluate the Isgur-Wise function and the decay constant F_B. The resulting
Isgur-Wise function predicts a large charge radius, rho^2 = 1.8 - 2.0, which
when fitted to the ARGUS data corresponds to the value Vcb = .044 - .050 for
the Kobayashi-Maskawa matrix element.


title:
The $s$-channel approach to Lipatov's pomeron and hadronic cross
  sections

abstract:
  We derive a generalized Balitskii-Fadin-Kuraev-Lipatov equation, which
applies directly to the perturbative QCD component of total cross section. With
the gluon correlation radius $R_{c} \sim 0.4$f we reproduce the empirical rate
of growth of the hadron-nucleon total cross sections. The simultaneous estimate
of the triple-pomeron coupling also agrees with the experiment.


title: Strange S--Wave Excitation of the NJL Soliton

abstract:
  The recently developed method to investigate mesonic fluctuations off the
chiral soliton in the Nambu--Jona--Lasinio model is applied to kaons in the
S--wave channel. It is shown that for commonly accepted choices of parameters
the presence of the soliton and the lack of confinement in this model provide
an unphysical (valence) quark threshold which is lower than the kaon mass.
Choosing parameters such that this threshold is avoided a bound state is
obtained in the S--wave channel. After semiclassical quantization this state
acquires the quantum numbers of an odd parity $\Lambda$ and is predicted at
about 420MeV above the nucleon mass.


title: Perspectives on Tau-Charm Factory Physics

abstract:
  The Tau-Charm Factory combines the optimum conditions to perform a
high-precision investigation of the $\tau$ and $\nu_\tau$ leptons, the $c$
quark, and light-quark, glueball and hybrid spectroscopy. An overview of the
broad physics program that this facility will address is presented.


title:
CP violation in a multi-Higgs doublet model with flavor changing neutral
  current

abstract:
  We study CP violation in a multi-Higgs doublet model based on a $S_3 \times
Z_3$ horizontal symmetry where CKM phase is not the principal source of CP
violation. We consider two mechanisms for CP violation in this model: a) CP
violation due to complex Yukawa couplings; and b) CP violation due to
scalar-pseudoscalar Higgs boson mixings. Both mechanisms can explain the
observed CP violation in the neutral Kaon system. $\epsilon'/\epsilon$ due to
neutral Higgs boson exchange is small in both mechanisms, but charged Higgs
boson con- tributions can be as large as $10^{-3}$ for a), and $10^{-4}$ for
b). CP violation in the neutral B system is, however, quite different from the
Minimal Standard
  Model. The neutron Electric Dipole Moment can be as large as the present ex-
perimental bound, and can be used to constrain charged Higgs boson masses.
  The electron
  EDM is one order of magnitude below the experimental bound in case b) and
smaller in case a).


title: Study of Constrained Minimal Supersymmetry

abstract:
  Taking seriously phenomenological indications for supersymmetry, we have made
a detailed study of unified minimal SUSY, including effects at the few percent
level in a consistent fashion. We report here a general analysis without
choosing a particular unification gauge group. We find that the encouraging
SUSY unification results of recent years do survive the challenge of a more
complete and accurate analysis. Taking into account effects at the 5-10% level
leads to several improvements of previous results, and allows us to sharpen our
predictions for SUSY in the light of unification. We perform a thorough study
of the parameter space. The results form a well-defined basis for comparing the
physics potential of different facilities. Very little of the acceptable
parameter space has been excluded by LEP or FNAL so far, but a significant
fraction can be covered when these accelerators are upgraded. A number of
initial applications to the understanding of the SUSY spectrum, detectability
of SUSY at LEP II or FNAL, BR($b\to s\gamma$), Width($Z\to b\bar b$), dark
matter, etc, are included in a separate section. We formulate an approach to
extracting SUSY parameters from data when superpartners are detected. For small
tan(beta) or large $m_top$ both $M_half$ and $M_0$ are entirely bounded from
above at O(1 tev) without having to use a fine-tuning constraint.


title: Tau Physics Prospects at the Tau-Charm Factory and at Other Machines

abstract:
  The prospects for tau physics at future high-luminosity facilities are
briefly discussed. Although important (and often complementary) contributions
will be made from other machines, the unique experimental environment near
threshold makes the Tau-Charm Factory the best experimental tool for $\tau$
physics.


title: $\gamma Z$ Pair Production at the Photon Linear Collider

abstract:
  $\gamma\gamma\to\gamma Z$ scattering at the Photon Linear Collider is
considered. Explicit formulas for helicity amplitudes due to $W$ boson loops
are presented. It is shown that the $Z\gamma$ pair production will be easily
observable at PLC and separation of the $W$ loop contribution will be possible
at $e^+e^-$ c.m. energy of 300~GeV or higher.


title: Short-range YN interactions in the Quark Cluster Model

abstract:
  A phenomenological model for the hyperon-nucleon interactions is constructed
by using the quark cluster model approach to the short-distance baryon-baryon
interactions. The model contains the SU(3) symmetric meson exchange interaction
at large distances and the quark-exchange short-distance interaction. The main
feature of the model is that strong channel dependences of the short range
repulsions due to the quark model symmetry. It is pointed out that two
channels, ($I$, $S$)= (1/2, 0) and (3/2, 1), of the S-wave sigma-nucleon
interactions have extremely strong repulsions at short-distances.


title: Multigluon Helicity Amplitudes Involving a Quark Loop

abstract:
  We apply the solution to the recursion relation for the double-off-shell
quark current to the problem of computing one loop amplitudes with an arbitrary
number of gluons. We are able to compute amplitudes for photon-gluon
scattering, electron-positron annihilation to gluons, and gluon-gluon
scattering via a quark loop in the case of like-helicity gluons. In addition,
we present the result for the one-loop gluon-gluon scattering amplitude when
one of the gluons has opposite helicity from the others.


title:
On the Precision of the Computation of the QCD Corrections to
  Electroweak Vacuum Polarizations

abstract:
  We demonstrate that the dispersive computation of the threshold enhancements
to heavy quark vacuum polarizations is unstable. Because of the slow
convergence of the dispersion relations the result critically depends on the
intermediate energy region where the non-relativistic approximation, intrinsic
to threshold calculations, is invalid. We discuss other ambiguities precluding
a reliable calculation of the threshold contribution to the vacuum
polarizations. In the absence of a solution prudence should force one to assign
an error to the radiative corrections not far below the level of the
pertubative O($\alpha \alpha_s$) contributions. This may preclude the
extraction of the Higgs mass from precision measurements.


title:
Searching for an Invisibly Decaying Higgs Boson in E^+E^-, E-Gamma, and
  Gamma-Gamma Collisions

abstract:
  Higgs bosons can have a substantial ``invisible'' branching ratio in many
extensions of the Standard Model, such as models where the Higgs bosons decay
predominantly into light or massless weakly interacting Goldstone bosons. In
this work, we examine the production mechanisms and backgrounds for invisibly
decaying Higgs bosons at the Next Linear $e^+e^-$ Collider operating in the
modes $e^+e^-$, $e\gamma$, and $\gamma\gamma$. We demonstrate that such machine
is much more efficient to survey for invisibly decaying Higgs bosons than the
Large Hadron Collider at CERN.


title:
$1/N_c$ Rotational Corrections to $g_A$ and Isovector Magnetic Moment of
  the Nucleon

abstract:
  The $1/N_c$ rotational corrections to the axial vector constant and the
isovector magnetic moment of the nucleon are studied in the Nambu --
Jona-Lasinio model. We follow a semiclassical quantization procedure in terms
of path integrals in which we can include perturbatively corrections in powers
of angular velocity $\Omega \sim \frac 1{N_c}$. We find non-zero $1/N_c$ order
corrections from both the valence and the Dirac sea quarks. These corrections
are large enough to resolve the long-standing problem of a strong
underestimation of both $g_A$ and $\mu^{IV}$ in the leading order. The axial
constant $g_A$ is well reproduced, whereas the isovector magnetic moment
$\mu^{IV}$ is still underestimated by 25 \%.


title: Spontaneous Current Generation in Cosmic Strings

abstract:
  It is shown that in models including the standard electroweak theory and for
some particular values of the underlying parameters, electric currents can be
spontaneously generated in cosmic strings, without the need of any external
field (e.g., electric or magnetic) as is required in most models. This
mechanism is then shown to break spontaneously the Lorentz invariance along the
initially Goto-Nambu string. The characteristic time needed for the current to
build up is estimated and found to lowest order to depend only on the mass of
the intermediate $W$ vector boson and the fine structure constant.


title: QCD Evolution Equations for High Energy Partons in Nuclear Matter

abstract:
  We derive a generalized form of Altarelli-Parisi equations to decribe the
time evolution of parton distributions in a nuclear medium. In the framework of
the leading logarithmic approximation, we obtain a set of coupled integro-
differential equations for the parton distribution functions and equations for
the virtuality (``age'') distribution of partons. In addition to parton
branching processes, we take into account fusion and scattering processes that
are specific to QCD in medium. Detailed balance between gain and loss terms in
the resulting evolution equations correctly accounts for both real and virtual
contributions which yields a natural cancellation of infrared divergences.


title: Gaugino Condensation as the Origin of Primordial Fluctuations

abstract:
  I present a model for inflation based on the gaugino-dilaton dynamics of
supersymmetry breaking. The inflaton is the dimension--1 scalar field $\phi$
related to the gaugino condensate via $\lambda^T\lambda=\phi^3.$ Recent work in
this area is used to obtain two significant results: (1) Scalar density
fluctuations at second horizon crossing are generated on scale $\lambda$ with
amplitude \[ \drr=A\cdot \ 10^3\cdot\
\left(\frac{m_{SUSY}}{m_{Pl}}\right)^{\half}\ \left(\frac{\lambda}{100\
\mbox{Mpc}}\right)^{0.03}\ \ , \] where $A$ is a constant which depends on
(unknown) details of gaugino-dilaton dynamics in the strong-coupling phase.
Agreement with COBE results is obtained if $A\simeq 2.$ \ (2) Due to mixing
with hidden sector glueballs, the dilaton mass is large $(\sim \left(\mp\
\ms^2\right)^ {\frac{1}{3}}\sim 10^8\ \mbox{GeV}),$ and reheating takes place
at $T\sim 1\tev.$ This {\em necessitates} that the presently observed baryon
asymmetry be generated at a cosmic temperature below 1 TeV.


title: Baryogenesis in the Singlet Majoron Model

abstract:
  The baryogenesis by decays of the right--handed neutrinos in the Majoron
model is studied. We show that compared to the observational value it is
possible to produce large enough baryon asymmetry in the Majoron model or, at
least, contribute strongly to it. It requires that the mass of the lightest
right--handed neutrino is about (or above) 1 TeV and the self coupling of the
singlet sector is weak enough, $ < 2\times 10^{-5}$, to prevent the
thermalization of the right--handed neutrinos by annihilations.


title: On the Interpretation of the Electroweak Precision Data

abstract:
  The recent precision electroweak data on $\Gamma^l, \bar s^2_W$ and $M_W/M_Z$
are compared with the tree-level and the dominant-fermion-loop as well as the
full one-loop standard-model predictions. While the tree-level predictions are
ruled out, the dominant-fermion-loop predictions, defined by using $\alpha
(M^2_Z)\cong 1/128.9$ in the tree-level formulae, as well as the full one-loop
predictions are consistent with the experimental data. Deviations from the
dominant-fermion-loop predictions are quantified in terms of an effective
Lagrangian containing three additional parameters which have a simple meaning
in terms of $SU(2)$ symmetry violation. The effective Lagrangian yields the
standard one-loop predictions for specific values of these parameters, which
are determined by $m_t$ and $m_H$.


title: Precision Tests of the Standard Model at LEP

abstract:
  Recent LEP results on electroweak precision measurements are reviewed.
Line-shape and asymmetries analysis on the Z peak is described. Then, the
consistency of the Standard Model predictions with experimental data and
consequent limits on the top mass are discussed. Finally, the possibility of
extracting information and constrains on new theoretical models from present
data is examined.


title: Equilibrium Relativistic Mass Distribution

abstract:
  The relativistic Maxwell-Boltzmann distribution for the system of $N$ events
with motion in space-time parametrized by an invariant ``historical time''
$\tau $ is considered without the simplifying approximation $m^2\cong M^2$,
where $M$ is a given intrinsic property of the events. The relativistic mass
distribution is obtained and the average values of $m$ and $m^2$ are
calculated. The average value of the energy in nonrelativistic limit gives a
correction of the order of 10\% to the Dulong-Petit law. Expressions for the
pressure and the density of events are obtained and the ideal gas law is
recovered.


title: Neutrino Mass Physics

abstract:
  Present limits on neutrino masses are briefly reviewed, along with
cosmological and astrophysical hints from dark matter, solar and atmospheric
neutrino observations that suggest neutrino masses. These would imply many
possible new phenomena such as neutrinoless $\beta\beta$ decay, lepton flavour
violating processes such as neutrino oscillations, $\mu \ra e \gamma$, $\mu \ra
3 e $, $\mu \ra e$ conversion in nuclei, as well as two-body decays with the
emission of a superweakly interacting spin zero particle, called majoron, e.g.
$\mu \ra e + J$. All of these processes may occur at levels consistent with
present or planned experimental sensitivities. The underlying physics may also
be probed at the high energies accessible at LEP, through related Z decay
processes. Another possible, albeit quite indirect, manifestation of massive
neutrinos is in Higgs physics. As an example I discuss the possibility of an
invisibly decaying Higgs, a quite generic feature of majoron models where the
lepton number is spontaneously violated close to the electroweak scale.


title: Equilibrium Relativistic Mass Distribution for Indistinguishable Events

abstract:
  A manifestly covariant relativistic statistical mechanics of the system of
$N$ indistinguishable events with motion in space-time parametrized by an
invariant ``historical time'' $\tau $ is considered. The relativistic mass
distribution for such a system is obtained from the equilibrium solution of the
generalized relativistic Boltzmann equation by integration over angular and
hyperbolic angular variables. All the characteristic averages are calculated.
Expressions for the pressure and the density of events are found and the
relativistic equation of state is obtained. The Galilean limit is considered;
the theory is shown to pass over to the usual nonrelativistic statistical
mechanics of indistinguishable particles.


title: Comment on: "Nucleon-nucleon scattering lengths in QCD sum rules,"

abstract:
  In a recent Physical Review Letter, Kondo and Morimatsu present a QCD sum
rule calculation of nucleon-nucleon scattering lengths. They also relate the
empirical scattering lengths to the nucleon mass shift in nuclear matter to
cast doubt on the "linear density approximation." In this Comment, we point out
flaws in both parts of their analysis and draw very different conclusions.