title: Asymmetric Gluon Distributions and Hard Diffractive Electroproduction

abstract:
  The ``asymmetric'' matrix element <p-r|G...G|p> that appears in the pQCD
description of hard diffractive electroproduction does not coincide with that
defining the gluon distribution function f_g(x). I outline a pQCD formalism
based on a concept of the double distribution F_g(x,y), which specifies the
fractions xp, yr, (1-y)r of the initial proton momentum p and the momentum
transfer r, resp., carried by the gluons. For $t \equiv r^2 =0$, r is
proportional to p: $r = \zeta p$, and it is convenient to parameterize the
matrix element <p-r|G...G|p> by an asymmetric distribution function ${\cal
F}_{\zeta}^g (X)$ depending on the total fractions $X \equiv x+y \zeta$ and
$X-\zeta = x- (1-y) \zeta$ of the initial hadron momentum p carried by the
gluons.I formulate evolution equations for ${\cal F}_{\zeta}^g (X)$, study some
of their general properties and discuss the relationship between ${\cal
F}_{\zeta}^g (X)$, F_g(x,y) and f_g(x).


title: Virtual LSPs at e+ e- Colliders

abstract:
  Currently popular search strategies for supersymmetric particles may be
significantly affected due to relatively light sneutrinos which decay
dominantly into invisible channels. In certain cases the second lightest
neutralino may also decay invisibly leading to two extra carriers of missing
energy (in addition to the lightest supersymmetric particle (LSP)) -- the
virtual LSPs (VLSPs). It is shown that if the sneutrino masses happen to be in
the small but experimentally allowed range ~ 45 - 55 GeV, these particles
together with neutralino pairs may contribute significantly to the missing
energy in the process e+ e- ---> \gamma + missing energy at LEP-2 energies as
an enhancement over the Standard Model or the conventional MSSM predictions. It
is further shown that a much larger region of the parameter space can be
scanned at a high luminosity e+ e- collider at 500 GeV like the proposed NLC
machine. Moreover this process can play a complementary role to direct chargino
searches at LEP-2 and NLC which may fail due to a near mass degeneracy of the
chargino and the sneutrino. Formulae for the cross sections taking into account
full mixings of the charginos and the neutralinos are derived. The signal
remains observable even in the context of more restricted models based on N=1
SUGRA with common scalar and gaugino masses. The effect of soft photon
brehmsstrahlung on the signal is also discussed briefly.


title:
Regularization at the next-to-leading order in the top-mode standard
  model without gauge bosons

abstract:
  We study Higgs condensation in the top-mode standard model at the
next-to-leading (NTL) order in 1/Nc, by calculating the effective potential as
a function of a hard mass term of the top quark. We include the effects of the
top and bottom quarks, all the scalars, and the leading QCD effects, but not
the effects of the transverse components of the electroweak gauge bosons. The
model contains finite UV energy cutoff parameters Lf, Lb for the fermionic and
the bosonic momenta. Condensation takes place at energies L \sim Lf \sim Lb. We
describe how to regularize the integrals over the fermionic momenta in a way
free of momentum branching ambiguities and treat the terms of 1/Nc expansion
mutually consistently. We use three different cutoff procedures. We also
discuss how to ensure the validity of Goldstone theorem. Demanding that the NTL
contributions not ``wash out'' the leading ones, we obtain for the cutoffs: L =
O(1 TeV), a result largely independent of the regularization procedure.


title: A confinement model calculation of h_1(x)

abstract:
  The transverse polarization distribution of quarks $h_1(x)$ is computed in a
confinement model, the chiral chromodielectric model. The flavor structure of
$h_1$, its $Q^2$ evolution and Soffer's inequality are studied. The Drell--Yan
double transverse asymmetry $A_{TT}$ is evaluated and found to be one order of
magnitude smaller than the double longitudinal asymmetry.


title: The Quantum Skyrmion in Representations of General Dimension

abstract:
  The representations of general dimension are constructed for the $SU(2)$
Skyrme model, treated quantum mechanically {\it ab initio. } This quantum
Skyrme model has a negative mass term correction, that is not present in the
classical Hamiltonian. The magnitude of the quantum mechanical mass correction
increases with the dimension of the representation of the $SU(2)$ group. In the
case of a 5-dimensional representation it is possible to obtain satisfactory
predictions for the nucleon mass with the empirical value for the pion decay
constant.


title: Determination of the chiral pion-pion scattering parameters: a proposal

abstract:
  An explicitly crossing-symmetric decomposition of the pion-pion scattering
amplitudes into low- and high-energy components is established. The high-energy
components are entirely determined by absorptive parts at high energies. With
the exception of the two leading-order parameters, all the parameters appearing
in the one- and two-loop chiral amplitudes are determined by the high-energy
components of the exact amplitudes.


title: Higgs Particles

abstract:
  Report of the Higgs Working Group to appear in the Proceedings of the
Workshop "Physics with $\ee$ Linear Colliders", Annecy-Gran Sasso-Hamburg, Feb.
4 - Sept. 1, 1995, P.M. Zerwas (editor).


title: Quantum Fields and Dissipation

abstract:
  The description of thermal or non-equilibrium systems necessitates a quantum
field theory which differs from the usual approach in two aspects: 1.The
Hilbert space is doubled; 2.Stable quasi-particles do not exist in interacting
systems. A mini-review of these two aspects is given from a practical viewpoint
including two applications. For thermal states it is shown how infrared
divergences occuring in perturbative quasi-particle theories are avoided,
whereas for non-equilibrium states a memory effect is shown to arise in the
thermalization.


title:
Q^2 Evolution of Chiral-Odd Twist-3 Distributions h_L(x, Q^2) and e(x,
  Q^2) in Large-N_c QCD

abstract:
  We prove that the twist-3 chiral-odd parton distributions obey simple
Gribov-Lipatov-Altarelli-Parisi evolution equations in the limit $N_c\to\infty$
and give analytic results for the corresponding anomalous dimensions. To this
end we introduce an evolution equation for the corresponding three-particle
twist-3 parton correlation functions and find an exact analytic solution. For
large values of n (operator dimension) we are further able to collect all
corrections subleading in N_c, so our final results are valid to
$O(1/N_c^2\cdot \ln(n)/n)$ accuracy.


title: The three-loop SSM $\beta$-functions

abstract:
  We present the supersymmetric standard model three-loop $\beta$-functions for
gauge and Yukawa couplings and consider the effect of three-loop corrections on
the standard running coupling analyses.


title: Regge asymptotics and color suppressed heavy meson decays

abstract:
  We discuss a possible generation of color suppressed B-decays amplitudes
through a soft final state interaction. As a typical example, we consider in
detail the decay $ \bar{B}^{0} \rightarrow D^{0} \pi^{0} $ (and also $
\bar{B}^{0} \rightarrow 2 \pi^{0} $). We show that in the approximation of the
two particle unitarity and at zero order in $ \alpha_{s} $ this process can be
related to the weak decay $ \bar{B}^{0} \rightarrow D^{+} \pi^{-} $ followed by
the strong charge exchange scattering in the Regge kinematics. We estimate the
amplitude of this process using the light cone QCD sum rule technique and find
that it is supppressed as a power of $ 1/m_{B} $ in comparison to the amplitude
generated by the effective non-leptonic Hamiltonian, but remains important for
the physical value of $m_{B}$.


title: On the Dalitz Plot Approach in Non-leptonic Charm Meson Decays

abstract:
  We claim that the non-resonant contribution to non-leptonic charm meson
decays may not be constant in the phase space of the reaction. We argue that
this can be relevant for any weak reaction. We discuss in detail the decay $D^+
\to K^- \pi^+ \pi^+$.


title: Effects of the gravivector and graviscalar fields in N=2,8 supergravity

abstract:
  The available tests of the equivalence principle constrain the mass of the
Higgs-like boson appearing in extended supergravity theories. We determine the
constraints imposed by high precision experiments on the antigravity fields
(gravivector and graviscalar) arising from $N=2,8$ supergravity.


title: Probing color-singlet exchange in $Z+2$-jet events at the LHC

abstract:
  The purely electroweak process $qq\to qqZ$ (via $t$-channel $\gamma/Z$ or $W$
exchange) provides a copious and fairly clean source of color-singlet exchange
events in $pp$ collisions at the LHC. A judicious choice of phase-space region
allows the suppression of QCD backgrounds to the level of the signal. The
color-singlet-exchange signal can be distinguished from QCD backgrounds by the
radiation patterns of additional minijets in individual events. A rapidity-gap
trigger at the minijet level substantially enhances the signal versus the
background. Analogous features of weak boson scattering events make $Z+2$-jet
events at the LHC an ideal laboratory for investigation of the soft-jet
activity expected in weak-boson scattering events.


title:
Natural Inflation in SUSY and Gauge-Mediated Curvature of the Flat
  Directions

abstract:
  Supersymmetric theories often include the non-compact directions in the field
space along which the tree level potential grows only up to a certain limited
value (determined by the mass scale of the theory) and then stays constant for
the arbitrarily large expectation value of the field parametrizing the
direction. Above the critical value, the tree-level curvature is large and
positive in the other directions. Such plateaux are natural candidates for the
hybrid inflaton. The non-zero F-term density along the plateau spontaneously
breaks SUSY and induces the one-loop logarithmic slope for the inflaton
potential. The coupling of the inflaton to the Higgs fields in the complex
representations of the gauge group, may result in a radiatively induced
Fayet--Iliopoulos D-term during inflation, which destabilizes some of the
squark and slepton flat directions. Corresponding soft masses can be larger
than the Hubble parameter and thus, play a crucial role for the Affleck--Dine
baryogenesis.


title:
Non-Abelian Weizsacker-Williams field and a two-dimensional effective
  color charge density for a very large nucleus

abstract:
  We consider a very large ultra-relativistic nucleus. Assuming a simple model
of the nucleus and weak coupling we find a classical solution for the gluon
field of the nucleus and construct the two-dimensional color charge density for
McLerran-Venugopalan model out of it. We prove that the density of states
distribution, as a function of color charge density, is Gaussian, confirming
the assumption made by McLerran and Venugopalan.


title: SUSY Contributions to R_b and Top Quark Decay

abstract:
  Stop contributions to radiative corrections to R_b and the top quark decay
are analysed over the relevant MSSM parameter space. One sees a 30 % increase
in the former along with a similar drop in the latter in going from the
higgsino dominated to the mixed region. Consequently one can get a viable SUSY
contribution to R_b within the constraint of the top quark data only in the
mixed region, corresponding to a photino dominated LSP. We discuss the
phenomenological implications of this model for top quark decay and direct stop
production, which can be tested with the Tevatron data.


title: On the Sum Rule Approach to Quarkonium-Hadron Interactions

abstract:
  We extend a recent sum rule calculation for inelastic quarkonium-hadron
interactions to realistic parton distribution functions; we also include finite
target-mass corrections. Both modifications are shown to have no significant
effect on the resulting cross section behaviour but the performed analysis
gives useful insights on the sum-rule approach in general.


title:
Perturbative rates and colour rearrangement effects in four-jet events
  at LEP2

abstract:
  An important issue in the direct reconstruction method of determining the $W$
mass from $q\bar q Q\bar Q$ events at LEP2 concerns the impact of the
relatively unknown QCD interconnection effects. It has been suggested that a
study of `short string' states, in which colour singlet states are formed from
$q \bar Q $ and $Q\bar q$ pairs with small phase--space separation, could shed
important light on this issue. We show that such configurations can also be
generated by conventional background $e^+e^-\ar 4$~parton processes, in
particular QCD $q \bar q g g$ and $q \bar q Q \bar Q$ and non--resonant
electroweak $q \bar q Q \bar Q$ production. We study the colour and kinematic
structure of these background contributions, and estimate the event rate to be
expected at LEP2. We find that the QCD processes are heavily suppressed, but
that non--resonant $q \bar q Q \bar Q$ production may be comparable in rate to
the expected `short string' signal from $W^+W^-$ production.


title: Nuclear modification of the flavor asymmetry ubar - dbar

abstract:
  In order to test the NMC finding of flavor asymmetry $\overline u-\overline
d$ in the nucleon, existing Drell-Yan data for the tungsten target are often
used. However, we have to be careful in comparing nuclear data with the nucleon
ones. We investigate whether there exists significant nuclear modification of
the $\overline u - \overline d$ distribution in a parton-recombination model.
It should be noted that a finite $\overline u - \overline d$ distribution is
theoretically possible in nuclei even if the sea is symmetric in the nucleon.
In neutron-excess nuclei such as the tungsten, there exist more $d$-valence
quarks than $u$-valence quarks, so that more $\overline d$-quarks are lost than
$\overline u$-quarks due to parton recombinations. Our results suggest that the
nuclear modification in the tungsten is a 2--10 \% effect on the NMC $\overline
u - \overline d$ distribution. The nuclear modification of the flavor asymmetry
should be an interesting topic in connection with ongoing Drell-Yan
experiments.


title:
Hard approximation in two-particle hadronic decays of B_c at large
  recoils

abstract:
  The two-particle decays of B_c^+ to psi pi^+(rho^+) and B_c^+ to eta_c
pi^+(rho^+) are considered in a way taking into account a soft binding of
quarks in the heavy quarkonia and a hard gluon exchange between the
constituents at large recoil momenta of psi(eta_c). An approximate double
enhancement of the amplitudes is found because of the nonspectator t-channel
contribution.


title: Supersymmetric Unified Models

abstract:
  Supersymmetry and Supersymmetric models are reviewed. Lecture given at the
KOSEF-JSPS Winter School, Recent Developments in Particle and Nuclear Theory
February 21- March 2, 1996,


title: One-loop results for three-gluon vertex in arbitrary gauge and dimension

abstract:
  We review the calculation of one-loop contributions to the three-gluon
vertex, for arbitrary (off-shell) external momenta, in arbitrary covariant
gauge and in arbitrary space-time dimension. We discuss how one can get the
results for all on-shell limits of interest directly from the general off-shell
expression.


title: Space-Dependent Probabilities for $K^0-\bar{K^0}$ Oscillations

abstract:
  We analyze $K^0-\bar{K^0}$ oscillations in space in terms of propagating wave
packets with coherent $K_S$ and $K_L$ components. The oscillation probabilities
$P_{K^0 \to K^0} (x)$ and $P_{K^0 \to \bar{K^0}} (x)$ depending only on the
distance $x$, are defined through the time integration of a current density
$j(x,t)$ . The definition is such that it coincides with the experimental
setting, thus avoiding some ambiguities and clarifying some controversies that
have been discussed recently.


title:
Effective Field Theory of Gravity, Reduction of Couplings and the
  Renormalization Group

abstract:
  The structure of the renormalization group equations for the low energy
effective theory of gravity coupled to a scalar field is presented. An
approximate solution to these equations with a finite number of independent
renormalized parameters can be found when the mass scale characteristic of the
fluctuations in the geometry is much smaller than the Planck mass. The
cosmological constant problem is reformulated in this context and some
conditions on the matter field content and interactions required in order to
have a sufficiently small cosmological constant are identified.


title: Polarized Lambdas in the Current Fragmentation Region

abstract:
  Data on the nucleon spin structure suggests that the $u$ (and $d$) quark
distributions in the $\Lambda$ hyperon may be polarized. If this correlation
carries over into fragmentation, then the study of polarized $\Lambda$'s in the
current fragmentation region of deep inelastic lepton scattering will be a
sensitive probe of nucleon spin structure. $\Lambda$ production by polarized
electrons from unpolarized targets can search for this correlation. If it is
signficant, $\Lambda$ production by unpolarized electrons from longitudinally
and transversely polarized targets can probe the $u$-quark helicity and
transversity distributions in the nucleon. We review what is known about quark
polarization in the $\Lambda$, summarize electroproduction of polarized
$\Lambda$s, and estimate the sensitivity to quark polarizations in the nucleon.
We also describe polarization phenomena associated with vector meson
electroproduction that can be observed in the same experimental regime.


title:
WOPPER, Version 1.5: A Monte Carlo Event Generator for e+e- to (W+W-) to
  4f + n gamma at LEP2 and beyond

abstract:
  We describe the new version of the Monte Carlo event generator WOPPER for
four fermion production through W-pairs including resummed leading logarithmic
QED radiative corrections. Among the new features included are singly resonant
background diagrams and anomalous triple gauge boson couplings.


title: Higgs Boson Masses in NMSSM with Spontaneous CP-violation

abstract:
  The Higgs boson mass problem is considered in the next-to-minimal
supersymmetric standard model for the case of the spontaneous CP violation. The
renormalization group equations for the gauge, Yukawa and scalar coupling
constants, the effective Higgs potential and lower experimental bounds on Higgs
boson and chargino masses are analyzed. The restrictions on the Higgs boson
masses are found.


title:
Hadronic Resonance Spectrum May Help in Resolution of Meson Nonet
  Enigmas

abstract:
  The identification of problematic meson states as the members of the quark
model $q\bar{q}$ nonets by using a hadronic resonance spectrum is discussed.
The results favor the currently adopted $q\bar{q}$ assignments for the
axial-vector, tensor, and 1 $^3F_4$ $J^{PC}=4^{++}$ meson nonets, and suggest a
new $q\bar{q}$ assignment for the scalar meson nonet which favors the
interpretation of the $f_0(980)$ and $f_0(1710)$ mesons as non-$q\bar{q}$
objects. We also suggest that the 2 $^3S_1$ $\frac{1}{2}(1^{-})$ state should
be identified with the $K^\ast (1680)$ rather than $K^\ast (1410)$ meson.


title:
Can the Aleph Four-Jet Excess be Explained in a Supersymmetric Model
  with R-Parity Violation?

abstract:
  We investigate the possibility that the excess of four-jet events in $e^+e^-$
collisions at LEP-1.5 which has been reported by the ALEPH Collaboration could
be due to the production of charginos or neutralinos, followed by their decay
into quark jets through baryon number-violating ($\lambda^{\prime\prime}$)
couplings. An estimate at the parton level shows, however, that these events
cannot be due to neutralinos because of the low cross-section, and is unlikely
to be due to the production of chargino pairs because of the largely different
event shapes.


title: When Is A Semiclassical Approximation Self-consistent?

abstract:
  A general condition for the self-consistency of a semiclassical approximation
to a given system is suggested. It is based on the eigenvalue distribution of
the relevant Hessian evaluated at the streamline configurations (configurations
that almost satisfy the classical equations of motion). The semiclassical
approximation is consistent when there exists a gap that separates small and
large eigenvalues and the spreading among the small eigenvalues is much smaller
than the gap. The idea is illustrated in the case of the double-well potential
problem in quantum mechanics. The feasibility of the present idea to test
instanton models of QCD vacuum is also briefly discussed.


title: Signatures of Color-Octet Quarkonium Production

abstract:
  I briefly review the nonrelativistic QCD picture of quarkonium production and
its confrontation with experiment in various production processes.


title: Inclusive Jet E_T Distributions and Light Gluinos

abstract:
  In the light gluino variant of the minimal supersymmetric model gluino pairs
can be readily produced in collider experiments even if the squarks are
arbitrarily heavy. This enhances the jet transverse energy distributions. In
addition the slower running of the strong coupling constant in the presence of
light gluinos leads to a further enhancement at higher transverse energies
relative to the standard $QCD$ expectations. Finally, the enhanced squark
gluino production would lead to a Jacobian peak in the $E_T$ distribution at
about $M_{\tilde Q}/2$. These effects are of about the right magnitude to
explain anomalies observed by the $CDF$ and $D0$ collaborations.


title: Dynamical Symmetry Breaking in a Gauge Theory ``Thirring Model''

abstract:
  Dynamical fermion mass generation is studied in the three-dimensional
Thirring model reformulated as a gauge theory by introducing hidden local
symmetry. The analysis by use of Schwinger-Dyson equation is shown to exhibit a
critical behavior as the number $N$ of four-component fermions approaches
$N_{\rm cr}=128/3\pi^{2}$.


title: Operator Product Expansion, Heavy Quarks, QCD Duality and its Violations

abstract:
  The quark (gluon)-hadron duality constitutes a basis for the theoretical
treatment of a wide range of inclusive processes -- from hadronic \tau decays
and R_{e^+e^-}, to semileptonic and nonleptonic decay rates of heavy flavor
hadrons. A theoretical analysis of these processes is carried out by using the
operator product expansion in the Euclidean domain, with subsequent analytic
continuation to the Minkowski domain. We formulate the notion of the quark
(gluon)-hadron duality in quantitative terms, then classify various
contributions leading to violations of duality. A prominent role in the
violations of duality seems to belong to the so called exponential terms which,
conceptually, may represent the (truncated) tail of the power series. A
qualitative model, relying on an instanton background field, is developed,
allowing one to get an estimate of the exponential terms. We then discuss a
number of applications, mostly from heavy quark physics.


title: QCD Analysis of Twist-4 Contributions to the $g_1$ Structure Functions

abstract:
  We analyze the twist-4 contributions to Bjorken and Ellis-Jaffe sum rules for
spin-dependent structure function $g_1(x, Q^2 )$. We investigate the anomalous
dimensions of the twist-4 operators which determine the logarithmic correction
to the $1/Q^2$ behavior of the twist-4 contribution by evaluating off-shell
Green's functions in both flavor non-singlet and singlet case. It is shown that
the EOM operators play an important role to extract the anomalous dimensions of
physical operators. The calculations to solve the operator mixing of
higher-twist operators are given in detail.


title: Top Quark Physics at a Future $e^+e^-$ Collider: Experimental Aspects

abstract:
  An overview of top physics and phenomenology at a high-energy linear collider
is presented. A comprehensive study of top quark physics is possible at such a
facility. The unique threshold production of top pairs would provide
measurements of fundamental properties, such as mass and total decay width, to
unmatched precision. Above threshold, the full set of Standard Model and
anomalous electroweak top couplings can be readily measured with excellent
precision. It should also be possible to measure the top Yukawa coupling. This
set of measurements would allow a definitive test of the widely held notion
that the top quark may play a special role in physics beyond the Standard
Model.


title: Multifractal Multiplicity Distribution in Bunching-Parameter Analysis

abstract:
  A new multiplicity distribution with multifractal properties which can be
used in high-energy physics and quantum optics is proposed. It may be
considered as a generalization of the negative-binomial distribution. We find
the structure of the generating function for such distribution and discuss its
properties.


title: Dynamical Supersymmetry Breaking without Messenger Gauge Interactions

abstract:
  We investigate low-energy models of supersymmetry (SUSY) breaking by means of
vector-like gauge theories for dynamical SUSY breaking. It is not necessary to
introduce messenger gauge interactions utilized so far to mediate the SUSY
breaking to the standard-model sector, which reduces complication in the model
building. We also consider various other ways of SUSY-breaking transmission.


title: Problems with Nonperturbative Effects in Deep Inelastic Scattering

abstract:
  We consider restrictions imposed on the (electromagnetic or weak) current
operator by its commutation relations with the representation operators of the
Poincare group and show that the nonperturbative part of the current operator
contributes to deep inelastic scattering even in leading order in $1/Q$ where
$Q$ is the magnitude of the momentum transfer. Some consequences of this result
are discussed.


title:
Theoretical Update on Two Non-Resonant Three-Body Channels in Charmed
  Meson Decays

abstract:
  Predictions of two channels in the three-bod decays of the charmed mesons are
made within the heavy hadron chiral perturbation theory. There still exists the
problem that the theoretical expectation is too small compared to the
experimental data.


title: Effects of colour reconnection in W+ W- events

abstract:
  We have investigated some observable consequences of colour reconnection in
the reaction e+e- -> W+ W- -> q_1 qbar_2 q_3 qbar_4. We use a measure based on
the momentum structure of the event, comparing reconnected events with
`standard' ones. Some different recoupling models are described and studied as
well as simpler toy models to show where the effects are present and what makes
most of them disappear in realistic models. Some attempts are made to introduce
suitable cuts in order to select the interesting events.


title: Discrete Ambiguities In Extracting Weak Phases from B decays

abstract:
  Phases of elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, as obtained
using decays of $B$ mesons to $\pi^+ \pi^-$, $\pi^\pm K^\mp$, and $\pi^+ K^0$
or $\pi^- \overline{K}^0$, are shown to have a class of discrete ambiguities.
In most cases these can be eliminated using other information on CKM phases.


title: Inflaton Decay in De Sitter Spacetime

abstract:
  We study the decay of scalar fields, in particular the inflaton, into lighter
scalars in a De Sitter spacetime background. After providing a practical
definition of the rate, we focus on the case of an inflaton interacting with a
massless scalar field either minimally or conformally coupled to the curvature.
The evolution equation for the expectation value of the inflaton is obtained to
one loop order in perturbation theory and the decay rate is recognized from the
solution. We find the remarkable result that this decay rate displays an
equilibrium Bose-enhancement factor with an effective temperature given by the
Hawking temperature $H\slash{2 \pi}$, where $H$ is the Hubble constant. This
contribution is interpreted as the ``stimulated emission'' of bosons in a
thermal bath at the Hawking temperature. In the context of new inflation
scenarios, we show that inflaton decay into conformally coupled massless fields
slows down the rolling of the expectation value. Decay into Goldstone bosons is
also studied. Contact with stochastic inflation is established by deriving the
Langevin equation for the coarse-grained expectation value of the inflaton
field to one-loop order in this model. We find that the noise is gaussian and
correlated (colored) and its correlations are related to the dissipative
(``decay'') kernel via a generalized fluctuation-dissipation relation.


title: W plus Heavy Quark Production at the Tevatron

abstract:
  We present the next-to-leading order QCD corrections to the production of a
$W$-boson in association with a jet containing a heavy quark. The calculation
is fully differential in the final state particle momenta and includes the mass
of the heavy quark. We study for the case of the Tevatron the sensitivity of
the cross section to the strange quark distribution function, the dependence of
the cross section on the heavy quark mass, the transverse momentum distribution
of the jet containing the heavy quark, and the momentum distribution of the
heavy quark in the jet.


title: Effective Chiral theory of Mesons

abstract:
  The meson fields are simulated by quark operators and an effective chiral
theory of mesons is presented. There are spontaneous chiral symmetry breaking
and dynamical chiral symmetry breaking. Theoretical results agree with data
well.


title: Precision Corrections in the Minimal Supersymmetric Standard Model

abstract:
  In this paper we compute one-loop corrections to masses and couplings in the
minimal supersymmetric standard model. We present explicit formulae for the
complete corrections and a set of compact approximations which hold over the
unified parameter space associated with radiative electroweak symmetry
breaking. We illustrate the importance of the corrections and the accuracy of
our approximations by scanning over the parameter space. We calculate the
supersymmetric one-loop corrections to the W-boson mass, the effective weak
mixing angle, and the quark and lepton masses, and discuss implications for
gauge and Yukawa coupling unification. We also compute the one-loop corrections
to the entire superpartner and Higgs-boson mass spectrum. We find significant
corrections over much of the parameter space, and illustrate that our
approximations are good to O(1%) for many of the superparticle masses.


title: Some Implications of Charge and Color Breaking in the MSSM

abstract:
  We examine some physically relevant implications of potentially dangerous
charge and color breaking minima for supersymmetric models. First, we analyze
the stability of the corresponding constraints with respect to variations of
the initial scale for the running of the soft breaking terms, finding that the
larger the scale is, the stronger the bounds become. In particular, by taking
$M_P$ rather than $M_X$ for the initial scale, which is a more sensible
election, we find substantially stronger and very important constraints.
Second, we find general bounds on the universal gaugino mass, the universal
scalar mass, $m\geq 55$ GeV, and the Higgs bilinear coefficient, $|B|\simlt
3m$. Finally, we study the infrared fixed point solution of the top quark mass.
Again, the constraints on the parameter space turn out to be very important,
including the analytically derivable bound $\left|M/m\right|\simlt 1$.


title: Unitarity and vector meson contributions to K^+ -> pi^+ gamma gamma

abstract:
  We compute the one-loop unitarity corrections O(p^6) from K^+ -> pi^+ pi^+
pi^- to K^+ -> pi^+ gamma gamma and we find they are relevant, increasing the
leading order prediction for the width in a 30-40%. The contributions of local
O(p^6) amplitudes, generated by vector meson exchange, are discussed in several
models and we conclude that the vector resonance contribution should be
negligible compared to the unitarity corrections.


title:
The Influence of the Full Vertex and Vacuum Polarization on the Fermion
  Propagator in QED3

abstract:
  We investigate the influence of the full vacuum polarization and vertex
function on the fermion propagator, using the coupled Dyson--Schwinger
equations for the photon and fermion propagator. We show that, within a range
of vertex functions, the general behavior of the fermion propagator does not
depend on the exact details of the vertex, both in the massless and in the
massive phase. Independent of the precise vertex function, there is a critical
number of fermion flavors for dynamical mass generation in $(2+1)$-dimensional
QED. A consistent treatment of the vacuum polarization is essential for these
results.


title:
The problems of unification-mismatch and low $\alpha_3$: A solution with
  light vector-like matter

abstract:
  The commonly accepted notion of a weak unified coupling $\alpha_X \approx
0.04$, based on the assumption of the MSSM--spectrum, is questioned. It is
suggested that the four--dimensional unified string coupling should very likely
have an intermediate value $(\sim 0.2-0.3$, say) so that it may be large enough
to stabilize the dilaton but not so large as to disturb the
coupling--unification relations. Bearing this in mind, as well as the smallness
of the MSSM unification scale $M_X$ compared to the string scale, the
consequences of a previously suggested extension of the MSSM spectrum are
explored. The extension contains two vector--like families of quarks and
leptons with relatively light masses of order 1 TeV, having the quantum numbers
of ${\bf 16}+{\bf \overline{16}}$ of $SO(10)$. It is observed that such an
extension provides certain unique advantages. These include: (a) removing the
stated mismatch between MSSM and string unifications with regard to $\alpha_X$
and to some extent $M_X$ as well, (b) achieving coupling unification with a
relatively low value of $\alpha_3(m_Z)$, in accord with its world average
value, and (c) following earlier works, providing a simple explanation of the
observed inter--family mass--hierarchy. The extension provides scope for
exciting new discoveries, beyond those of SUSY and Higgs particles, at future
colliders, including the LHC and the NLC.


title: Feynman Diagrams to Three Loops in Three Dimensional Field Theory

abstract:
  The two point integrals contributing to the self energy of a particle in a
three dimensional quantum field theory are calculated to two loop order in
perturbation theory as well as the vacuum ones contributing to the effective
potential to three loop order. For almost every integral an expression in terms
of elementary and dilogarithm functions is obtained. For two integrals, the
master integral and the Mercedes integral, a one dimensional integral
representation is obtained with an integrand consisting only of elementary
functions. The results are applied to a scalar $\lambda\phi^4$ theory.


title: Direct CP violation of B meson via rho-omega interference

abstract:
  We investigate $B^{\pm,0}\rightarrow \rho^0 (\omega )h^{\pm,0}$, where
$\rho^0 (\omega)$ decays to $\pi^+\pi^-$ and $h$ is any hadronic final states,
such as $\pi$ or $K$. We find large direct $CP$ asymmetries via $\rho-\omega$
interference. A possible determination of the weak phases, such as $\phi_2={\rm
arg}((V_{ud}V^*_{ub})/(V_{td}V^*_{tb}))$ and $\phi_3={\rm
arg}((V_{us}V^*_{ub})/(V_{ts}V^*_{tb}))$, is also discussed. We show the
feasibility to detect the CP asymmetries in these channels by assuming an
asymmetric $e^+e^-$ collider experiment. $10^{9}$ $B\bar B$ events are required
for the detection of this effect.


title: Left-handed neutrino disappearance probe of neutrino mass and character

abstract:
  We explore the sensitivity to a non vanishing neutrino mass offered by
dynamical observables, i.e., branching ratios and polarizations. The
longitudinal polarization in the C.M. frame decreases by a 4% for $D^+
\rightarrow \tau^+ \nu_\tau$ and $m_{\nu_\tau}=24$ MeV. Taking advantage of the
fact that the polarization is a Lorentz variant quantity, we study the
polarization effects in a boosted frame. By means of a neutrino beam, produced
by a high velocity boosted parent able to flip the neutrino helicity, we find
that an enhanced left-handed neutrino deficit, induced by a Wigner rotation,
appears.


title: On the Decay Mode $B^- \to \mu^- \bar \nu_\mu \gamma$

abstract:
  A QCD relativistic potential model is employed to compute the decay rate and
the photon spectrum of the process $B^- \to \mu^- {\bar \nu}_\mu \gamma$. The
result ${\cal B}(B^- \to \mu^- {\bar \nu}_\mu \gamma) \simeq 1 \times 10^{-6}$
confirms the enhancement of this decay channel with respect to the purely
leptonic mode, and supports the proposal of using this process to access
relevant hadronic quantities such as the $B$-meson leptonic decay constant and
the CKM matrix element $V_{ub}$.


title:
QCD predictions for annihilation decays of P-wave quarkonia to
  next-to-leading order in $\alpha_s$

abstract:
  The decay rates of P-wave heavy quarkonia to light hadrons are presented to
leading order in $v^2$ and next-to-leading order in $\alpha_s$. They include
contributions from both the color-singlet component and the color-octet
component of quarkonia. Applying these results to charmonium and using measured
decay rates for the $\chi_{c1}$ and $\chi_{c2}$ by E760, we determine the two
nonperturbative decay matrix elements, and then predict the hadronic decay
rates of $\chi_{c0}$ and $h_c$, and the electromagnetic decay rates of
$\chi_{c0}$ and $\chi_{c2}$. The obtained decay rates of $\chi_{c0}\to LH$ and
$\chi_{c0}\to\gamma\gamma$ are in agreement with the Crystal Ball result, and
also with the new measurement by BES. However, the results for
$\Gamma(\chi_{c0}\to LH)$ are dependent on the choice of renormalization scale.


title: Neutrino Flavor Mixing in the `Doublet-Singlet Oscillation' Model

abstract:
  Recently, it was pointed out that the solar and atmospheric neutrino deficits
can be explained by oscillations between electroweak doublet and singlet
neutrinos in the model of Majorana neutrinos. However, since the model includes
no flavor mixing, it cannot explain the recent LSND result. We extend the model
to include the flavor mixing, and obtain the explanation of the LSND result
together with the solar and atmospheric neutrino deficits. The requirement for
the neutrinos to be the hot dark matter selects out only the vacuum oscillation
solution to the solar neutrino deficit.


title: Effective Field Theories

abstract:
  These lectures introduce some of the basic ideas of effective field theories.
The topics discussed include: relevant and irrelevant operators and scaling,
renormalization in effective field theories, decoupling of heavy particles,
power counting, and naive dimensional analysis. Effective Lagrangians are used
to study the $\Delta S=2$ weak interactions and chiral perturbation theory.


title: Electroweak Baryogenesis and the Expansion Rate of the Universe

abstract:
  The standard requirement for the production of baryons at the electroweak
phase transition, that the phase transition be first order and the sphaleron
bound be satisfied, is predicated on the assumption of a radiation dominated
universe at that epoch. One simple alternative - domination by the energy in a
kinetic mode of a scalar field which scales as $1/a^6$ - gives a significantly
weakened sphaleron bound for the preservation of a baryon asymmetry produced at
a first-order phase transition, and allows the possibility that the observed
baryon asymmetry be produced when the phase transition is second-order or
cross-over. Such a phase of `kination' at the electroweak scale can occur in
various ways as a scalar field evolves in an exponential potential after
inflation.


title:
Constraints on "Second Order Fixed Point" QCD from the CCFR Data on Deep
  Inelastic Neutrino-Nucleon Scattering

abstract:
  The results of LO {\it Fixed point} QCD (FP-QCD) analysis of the CCFR data
for the nucleon structure function $~xF_3(x,Q^2)~$ are presented. The
predictions of FP-QCD, in which the Callan-Symanzik $~\beta~$ function admits a
{\it second order} ultraviolet zero at $~\alpha = \alpha_0~$ are in good
agreement with the data. Constraints for the possible values of the $~\beta~$
function parameter $~b~$ regulating how fast $~\alpha_ s(Q^2)~$ tends to its
asymptotic value $~\alpha_{0}\ne 0~$ are found from the data. The corresponding
values of $~\alpha_{0}~$ are also determined. Having in mind our recent " First
order fixed point" QCD fit to the same data we conclude that in spite of the
high precision and the large $~(x,Q^2)~$ kinematic range of the CCFR data they
cannot discriminate between QCD and FP-QCD predictions for $~xF_3(x,Q^2)~$.


title: Four leptons final states from $\gamma\gamma$ fusion

abstract:
  I present a systematic study of all possible four leptons final states from
$\gamma\gamma$ collisions. It is given a detailed account of fermion masses
effects which are sizable since several collinear and $t$ channel enancements
occur. The effects of angular cuts on the final charged leptons are also
discussed. To perform the computation I have used the recently developed ALPHA
algorithm (and the resulting code) for the automatic computation of scattering
amplitudes.


title: A complete solution to neutrino mixing

abstract:
  Deviations from expectations have been claimed for solar, atmospheric and
high energy prompt neutrinos from charm decay. This information, supplemented
only by the existing very good upper limits for oscillations of the $\nu_{\mu}$
at accelerator energies, is used as input to a phenomenological three-flavour
analysis of neutrino mixing. The solution found is unique and completely
determines the mass eigenstates as well as the mixing matrix relating mass and
flavour eigenstates. Assuming the mass eigenstates to follow the hierarchy
$m_{1} \ll m_{2} \ll m_{3}$, their values are found to be $m_{1} \ll 10^{-2}$
eV, $m_{2} = (0.18 \pm 0.06)$ eV, $m_{3} = (19.4 \pm 0.7)$ eV. These masses are
in agreement with the leptonic quadratic hierarchy of the see-saw model and
large enough to render energy-independent any oscillation-induced phenomenon in
solar neutrino physics observable on Earth. This possibility is not excluded by
the present knowledge of solar neutrino physics. The mixing angles are
determined to be $\theta_{12} = 0.55 \pm 0.08$, $\theta_{13} = 0.38 \pm 0.06$,
$\theta_{23} < 0.03$. Small values of $\theta_{23}$ are typical of any solution
in which $m_{3}$ lies in the cosmological interesting region. The solution
found is not in serious contradiction with any of the present limits to the
existence of neutrino oscillations. The most relevant implications in particle
physics, astrophysics and cosmology are discussed.


title: Rb and Heavy Quark Mixing

abstract:
  In this talk I summarize a part of the work done in a recent collaboration
with C. Burgess, J. Cline, D. London and E. Nardi \cite{b96}. We analyze the
observed discrepancy between $R_b(\equiv\gb /\ghad )$ as measured at LEP and
its standard model value for signals of new physics. The focus is thereby put
on new physics that manifests itself through heavy quark mixing. Heavy quark
mixing affects the measured value of $R_b$ in two ways: at tree level (bottom
mixing) and at one-loop level (top mixing). One finds that whereas the latter
cannot account for the deviation, bottom mixing can in principle do the job.


title: Low Energy Tests of Chiral Symmetry

abstract:
  The present status of low energy test of chiral invariance via chiral
perturbation theory is reviewed, both in the meson and baryon sectors, and
future prospects are discussed.


title: Color-Singlet $\psi_Q$ Production at $e^+e^-$ Colliders

abstract:
  We calculate in closed form the complete ${\mathcal O}(\alpha_s^2)$
color-singlet differential cross section for $e^+e^- \to \gamma^* \to \psi_Q+X$
scattering. The cross section reduces at high energies to a heavy quark
fragmentation form. We find that the energy scale at which the approximate
fragmentation result becomes reliable exceeds the $\psi_Q$ mass by more than an
order of magnitude. We also discuss the color-singlet model's predictions for
direct $J/\psi$ angular and energy distributions at CLEO.


title:
Three-Loop Polarization Function and ${\cal O}(\alpha_s^2)$ Corrections
  to the Production of Heavy Quarks

abstract:
  The three-loop vacuum polarization function $\Pi(q^2)$ induced by a massive
quark is calculated. A comprehensive description of the method is presented.
From the imaginary part the ${\cal O}(\alpha_s^2)$ result for the production of
heavy quarks $R(s)=\sigma(e^+e^-\to \mbox{hadrons})/\sigma(e^+e^-\to
\mu^+\mu^-)$ can be extracted. Explicit formulae separated into the different
colour factors are given.


title: Searching for $t \to c g$ at the Fermilab Tevatron

abstract:
  We examine the experimental observability of the decay mode $t \rightarrow c
g$ at the Fermilab Tevatron via the flavor-changing neutral current vertex $t
\bar c g$. We find that with the existing data, one should be able to probe the
$t \bar c g$ coupling to a value smaller than indirect limits previously
obtained from $b\rightarrow s \gamma$ and the measured branching fraction for
$t\rightarrow bW$, reaching $BF(t \rightarrow cg) \sim$ 15\% - 28\%. A data
sample of 1~fb$^{-1}$ (10~fb$^{-1}$) at $\sqrt{s}=2$~TeV may probe the $t
\rightarrow c g$ branching fraction to a level of 2\% (0.5\%).


title: R_b Problem: Loop Contributions and Supersymmetry

abstract:
  I summarize a part of the work done with Bamert, Burgess, London and Nardi
(hep-ph/9602438) in which we find simplified expressions for the possible
one-loop contributions to the $R_b$ parameter from new virtual particles,
including supersymmetric ones. Our expressions make it easier to identify which
models and choices of parameters are best able to solve the $R_b$ problem.


title: Precision Electroweak Constraints on Top-Color Assisted Technicolor

abstract:
  Using precision electroweak data, we put limits on ``natural'' top-color
assisted technicolor models. Generically the new $U(1)$ gauge bosons in these
models must have masses larger than roughly 2 TeV, although in certain
(seemingly unrealistic) models the bound can be much lower.


title: Analytic study of disoriented chiral condensate

abstract:
  Evolution of disoriented chiral condenstates is studied with the classical
sigma model in 3+1 dimensions. By smoothly connecting a chiral symmetric
solution of the formation period to a solution of the decay period, we obtain a
complete spacetime evolution of the pion field for a simple and physically
interesting source. The formation process is discussed quantitatively from the
viewpoint of the axial-vector isospin conservation.


title: On Measuring CP Violating Phase $\gamma$ Using Neutral $B$ Decays

abstract:
  We propose two independent methods to determine the CKM phase $\gamma$ and
the tree and penguin amplitudes using neutral $B$ decays, assuming that the
phase $\beta$ is known. Based on flavor SU(3) symmetry and SU(3) breaking
effect, one method uses the decay processes $B^0(t) \rightarrow \pi^0 K_S$,
$B^0 \rightarrow \eta K^0 \; (K_S \rightarrow \pi \pi)$ and their
charge-conjugate processes, and the other uses the processes $B^0(t)
\rightarrow \pi^0 K_S$, $B^0 \rightarrow \pi^0 \pi^0$ and their
charge-conjugate processes. From SU(3) breaking consideration, the latter
method would be more useful.


title: Jet Algorithms and Top Quark Mass Measurement

abstract:
  Mass measurements of objects that decay into hadronic jets, such as the top
quark, are shown to be improved by using a variant of the $k_t$ jet algorithm
in place of standard cone algorithms. The possibility and importance of better
estimating the neutrino component in tagged $b$ jets is demonstrated. These
techniques will also be useful in the search for Higgs boson $\to b \bar b$.


title: Stability Bounds on Flavor-Violating Trilinear Soft Terms in the MSSM

abstract:
  The stability of the standard vacuum imposes constraints on flavor violating
trilinear soft terms which are stronger than the laboratory bounds coming from
the absence of neutral flavor violations (FCNC). Furthermore, contrary to the
FCNC bounds, these constraints persist even if the scale of supersymmetry
breaking is arbitrarily large.


title: A new approach to the momentum expansion of multiloop Feynman diagrams

abstract:
  We present a new method for the momentum expansion of Feynman integrals with
arbitrary masses and any number of loops and external momenta. By using the
parametric representation we derive a generating function for the coefficients
of the small momentum expansion of an arbitrary diagram. The method is
applicable for the expansion w.r.t. all or a subset of external momenta. The
coefficients of the expansion are obtained by applying a differential operator
to a given integral with shifted value of the space-time dimension $d$ and the
expansion momenta set equal to zero. Integrals with changed $d$ are evaluated
by using the generalized recurrence relations proposed in \cite{OVT1}. We show
how the method works for one- and two-loop integrals. It is also illustrated
that our method is simpler and more efficient than others.


title:
Chiral Scalar Fields, Custodial Symmetry in Electroweak SU(2)L X U(1)
  and the Quantization of the Electric Charge

abstract:
  I study the scalar representations of the electroweak group of the Standard
Model, which is a subgroup of the chiral group U(N)L x U(N)R with N flavours,
for N even, with a special emphasis on their chiral properties and on their
behaviour by the discrete symmetries P and CP. They exhaust the $2N^2$ scalar
and pseudoscalar degrees of freedom of the chiral group, for which a SU(2)L x
U(1) renormalizable, anomaly-free gauge theory naturally springs out. It is
shown to have a global diagonal SU(2)V symmetry independently of the value of
the hypercharge coupling, which becomes local at the limit when the latter
vanishes. When acting in the 4-dimensional space of states spanned by the
special representations under scrutiny in this paper, the electric charge is
one of the three generators of this ``custodial'' symmetry; that the latter
stays an unbroken symmetry is thus correlated with the quantization of the
electric charge.


title: QED Radiative Corrections in Exclusive $\rho^0$ Leptoproduction

abstract:
  The semi-analytical approach to the model independent leptonic QED
corrections to exclusive $\rho^0$ meson leptoproduction (i.e. electron and muon
scattering experiments) is presented. The corrections to $\rho^0$ production at
large $Q^2$ as well as to $\rho^0$ photoproduction are studied in details. The
numerical results are calculated for two different experimental analyses: NMC
(muoproduction at large $Q^2$) and ZEUS at HERA (photoproduction). It is shown
that the corrections are 2-5 \% for NMC and below 2 \% for the ZEUS
measurement. The application of the presented approach to other vector mesons
production is straightforward.


title: Flattening the Inflaton's Potential with Quantum Corrections

abstract:
  I show that a classical scalar potential with $ V''/V \sim 1 $ can be
sufficiently flattened by quantum corrections to give rise to slow-roll
inflation. This provides perhaps the simplest way to generate an inflationary
potential without fine tuning. The most natural implementation of this idea
produces an unviably small spectral index, but, for example, $ n \sim 0.8 $ can
be obtained in other implementations.


title:
The Coefficient \eta_3 of the |\Delta S|=2 Hamiltonian in the
  Next-To-Leading Order

abstract:
  I present the calculation of the QCD short distance coefficient $\eta_3$ of
the $|\Delta S|=2$-hamiltonian in the next-to-leading order (NLO) of
renormalization group improved perturbation theory. It involves the two-loop
mixing of bilocal structures composed of two $|\Delta S|=1$ operators into
$|\Delta S|=2$ operators. The next-to-leading order corrections enhance
$\eta_3$ by 27\% to $\eta_3=0.47\errorpm{0.03}{0.04}$ thereby affecting the
phenomenology of the CP-parameter $\epsilon_K$ sizeably. $\eta_3$ depends on
the physical input parameters $m_t$, $m_c$ and $\Lambda_{MSbar}$ only weakly.
The quoted error stems from factorization scale dependences, which have reduced
compared to the old leading log result. We further discuss some field
theoretical aspects of the calculation such as the renormalization group
equation for Green's functions with two operator insertions and the
renormalization scheme dependence caused by the presence of evanescent
operators. This article is based on work done in collaboration with U.~Nierste.


title:
The controversy in the $\gamma\gamma\to\rho\rho$ process: potential
  scattering or $qq\bar{q}\bar{q}$ resonance ?

abstract:
  The $\gamma\gamma\to\rho^0\rho^0\to 4 \pi$ reaction shows a broad peak at 1.5
GeV in the $(J^P,J_z)=(2^+,2)$ channel which has no counterpart in the
$\rho^+\rho^-$ channel. This "resonance" is considered as a candidate for a
$qq\bar q\bar q$ state in the "s-channel". We show, however, that it can also
be explained by potential scattering of $\rho^0\rho^0$ via the $\sigma$-
exchange in the "t-channel".


title:
Small-threshold behaviour of two-loop self-energy diagrams: some special
  cases

abstract:
  An algorithm to construct analytic approximations to two-loop diagrams
describing their behaviour at small non-zero thresholds is discussed. For some
special cases (involving two different-scale mass parameters), several terms of
the expansion are obtained.


title: Momentum Dependence of the Penguin Interaction

abstract:
  We have considered the penguin interaction contribution to $K \rightarrow 2
\pi$ decays. In particular, we have investigated the effect of the momentum
dependence of the penguin coefficient. Our analysis is performed within the
Chiral Quark Model where quarks are coupled to the pseudoscalar mesons, which
means that hadronic matrix elements can be calculated in terms of quark loop
diagrams. We have inserted the momentum dependent penguin coefficient into the
relevant quark loop diagrams for $K \rightarrow \pi$. We discuss two possible
prescriptions for performing the calculations, and conclude that the momentum
dependence of the penguin coefficient increases the amplitude by 10-20 $\%$. In
any case, the (CP-conserving) penguin contribution is very sensitive to the
values chosen for the involved parameters.


title: A New Method to Probe the low $x$ Parton Dynamics at HERA

abstract:
  Hadron transverse momentum spectra are proposed as a means to probe the
underlying partonic dynamics in deep inelastic scattering. The BFKL evolution
equation, postulated for small Bjorken-$x$, leads to an enhanced parton
emission over the conventional DGLAP ansatz, and can thus be tested.


title:
On the Necessity of Recalibrating Heavy Flavor Decays and its Impact on
  Apparent Puzzles in High Energy Physics

abstract:
  It is demonstrated that charm is systematically undercounted in various
experiments. Via a process of elimination, $B(D^0 \rightarrow K^- \pi^+ )$ is
identified as the culprit. It calibrates essentially all charmed meson
production and decay properties, and thus is central to the physics of heavy
flavors. We predict it to decrease significantly below currently accepted
values. We suggest several novel methods for precise measurements of $B(D^0
\rightarrow K^- \pi^+ )$. The $B(\Lambda_c \rightarrow pK^-\pi^+)$, on the
other hand, calibrates heavy-flavored baryons. Its world average relies heavily
on a model of baryon production in $B$ decays, which would be invalidated if
$\overline B\rightarrow D^{(*)} \stackrel{(-)}{N} X$ processes were found to be
significant. A Dalitz-plot analysis explains naturally the soft inclusive
$\Lambda_c$ momentum spectrum in $\overline B$ decays, and predicts sizable
$\overline B\rightarrow D^{(*)}\stackrel{(-)}{N} X$ processes. Consistently
carrying through these modifications to charmed meson and baryon yields has the
potential to resolve the heavy-flavor puzzles at $Z^0$-factories [$R_c,\;
R_b$], the number of charm per $B$-decay puzzle, and the semi-leptonic $B$
decay puzzles. We emphasize that state of the art theoretical calculations are
consistent with precise experimental measurements regarding $B(\overline
B\rightarrow X\ell\bar\nu )$. Recent CLEO measurements are interpreted as newly
available cross-checks that any inclusive theoretical investigation must
satisfy. Another topic of this report concerns the $b\rightarrow c + \overline
D^{(*)}\overline K$ transitions, which were predicted to be sizable and
subsequently confirmed by CLEO. This report discusses the underlying dynamics
of those processes and quantifies the necessary modifications in existing


title:
The Extended Nambu-Jona-Lasinio Model and Hidden Local Symmetry of Low
  Energy QCD

abstract:
  Using the standard auxiliary field method, we derive from the extended
Nambu-Jona-Lasinio model an effective meson action containing vector and
axial-vector mesons in addition to Goldstone bosons. The vector and
axial-vector mesons in this effective action transform as gauge fields of
hidden local symmetry $G_{local} = {[U(n)_L \times U(n)_R]}_{local}$. Here, the
realization of enlarged hidden local symmetry is accomplished via the
introduction of two kinds of ``compensating'' fields. For obtaining the
intrinsic-parity violating part of the action, we generalize the standard
gauged Wess-Zumino-Witten action such that it also contains two kinds of
``compensators'' in addition to the usual Goldstone bosons as well as the
vector and axial-vector mesons. This generalized gauged Wess-Zumino-Witten
action turns out to have $G_{globa} \times G_{local}$ symmetry, where
$G_{global}$ being the usual $U(n)_L \times U(n)_R$ global chiral symmetry
while $G_{local}$ being the $U(n)_L \times U(n)_R$ hidden local symmetry. This
means that $G_{local}$ has no gauge anomaly and its associated vector and
axial-vector mesons can be regarded as gauge bosons of $G_{local}$. The
introduction of the coupling with the external electroweak fields requires us
to gauge some appropriate subgroup of $G_{global}$. To perform it in consistent
with the anomaly structure of QCD is a nontrivial problem. We explain how this
can be done, following the recent suggestion by several authors.


title: Ten Years of the Fifth Force

abstract:
  The suggestion in 1986 of a possible gravity-like ``fifth" fundamental force
renewed interest in the question of whether new macroscopic forces are present
in nature. Such forces are predicted in many theories which unify gravity with
the other known forces, and their presence can be detected by searching for
apparent deviations from the predictions of Newtonian gravity. We review the
phenomenology behind searches for a ``fifth force", and present a summary of
the existing experimental constraints.


title: A Lower Bound on Neutrino Mass

abstract:
  The exchange of massless neutrinos between heavy fermions (e.g. $e,p,n$)
gives rise to a long-range 2-body force. It is shown that the analogous
many-body force can lead to an unphysically large energy density in white
dwarfs and neutron stars. To reduce the energy density to a physically
acceptable value, the neutrino must have a {\it minimum mass}, which is
approximately $0.4\;eV/c^2$. Some recent questions relating to the derivation
of this bound are also discussed.


title: Neutrino Masses and Mixing in Supersymmetric Models without $R$ Parity

abstract:
  We study neutrino masses and mixing in Supersymmetric Models without $R$
parity and with generic soft Supersymmetry breaking terms. Neutrinos acquire
mass from various sources: tree level neutrino--neutralino mixing, loop effects
and non--renormalizable operators. Abelian horizontal symmetries (invoked to
explain the smallness and hierarchy in quark parameters) replace $R$ parity in
suppressing neutrino masses. We find lower bounds on the mixing angles:
$\sin\theta_{ij} \gsim m(\ell_i^-)/m(\ell_j^-)$ ($i<j$) and unusual order of
magnitude predictions for neutrino mass ratios:
$m(\nu_e)/m(\nu_\mu)\sim\sin^2\theta_{12}$; $m(\nu_i)/m(\nu_\tau)\sim 10^{-7}
\sin^2\theta_{i3}$ ($i=1,2$). Bounds from laboratory experiments exclude
$m_{\nu_\tau} \gsim 3\ MeV$ and the cosmological constraint that excludes
$m_{\nu_\tau} \gsim 100\ eV$ is not evaded. Neither the solar nor the
atmospheric neutrino problems are likely to be solved by $\nu_\mu-\nu_e$
oscillations. These conclusions can be evaded if holomorphy plays an important
role in the lepton Yukawa couplings.


title: Charmonium Production

abstract:
  Theoretical analyses of the results on quarkonium production at large
transverse momentum ($p_T$) in $p\bar p$ collisions, at the Tevatron have
revealed two novel features of the physics of quarkonium production : 1) the
contribution of fragmentation of gluons and charm quarks to the cross-section
at large $p_T$, and 2) the importance of colour octet components of the
quarkonium wave-function. I discuss the theoretical developments which have
contributed to a reasonably consistent picture of quarkonium production at the
Tevatron, and discuss large-$p_T$ $J/\psi$ production at HERA and at LHC as
important tests of the fragmentation picture. I also discuss our recent
analysis of $J/\psi$ production cross-sections at fixed-target energies, where
we find that the energy dependence of the $p_T$-integrated cross-sections for
both $pp$ and $\pi^- - p$ collisions is reasonably well reproduced, when the
colour-octet components are included.


title: Electroweak radiative corrections in Z boson decays

abstract:
  Contribution to A.D.Sakharov memorial volume. A detailed review of the
electroweak radiative corrections to the Z-boson decays in the framework of the
Minimal Standard Modelm (MSM) is presented. After a short historical
introduction we describe the optimal parametrization of the MSM, especially of
the Born approximation, and derive expressions for the one-loop electroweak
corrections. Finally a global fit of all relevant experimental data is
performed, resulting in fitted values of the top-quark mass, m_t, and strong
coupling constant /alpha_s. Allowed range for the value of the Higgs mass, m_H,
is discussed. Various details of calculations are described in 16 appendices.


title:
The Singlet Contribution to the Structure Function $g_1(x,Q^2)$ at Small
  $x$

abstract:
  The resummation of $O(\alpha_s^{l+1} \ln^{2l} x)$ terms in the evolution
equation of the singlet part of $g_1(x,Q^2)$ is carried out. The corresponding
singlet evolution kernels are calculated explicitely. The leading small-$x$
contribution to the three-loop splitting function matrix is determined in the
$\overline{\rm MS}$ scheme. Relations are derived for the case of ${\cal N} =
1$ supersymmetric Yang--Mills field theory. Numerical results are presented for
the polarized singlet and gluon densities, and the structure functions $g_1^{\,
p}(x,Q^2)$ and $g_1^{\, n}(x,Q^2)$. They are compared for different assumptions
on the non--perturbative input distributions, and the stability of the results
against presently unknown subleading contributions is investigated.


title:
$K\bar{K}$ Threshold Phenomena, $f_0-a_0$ Interference and Kaonium
  Production

abstract:
  We develop a new formalism to study $K\bar{K}$ threshold phenomena with
resonances $f_0$, $a_0$ and $K^+K^-$ atom (kaonium) included. The approach
provides two possible scenarios for $f_0-a_0$ mixing. Drastic interference
patterns can be observed in $K^+K^-$electroproduction at CEBAF, $pd\to ~^3HeX$
reaction, and $N\bar N$ annihilation.


title:
New Signatures for a Light Stop at LEP2 in SUSY Models with
  Spontaneously Broken R-Parity

abstract:
  In a class of supersymmetric models with R-parity breaking the lightest stop
can have new decay modes into third generation fermions, $\tilde{t}_1
\rightarrow b + \tau$. We show that this decay may be dominant or at least
comparable to the ordinary R-parity conserving mode $\tilde{t}_1 \rightarrow c
+ \tilde{\chi}_1^0$, where $\tilde{\chi}_1^0$ denotes the lightest neutralino.
The new R-parity violating decay mode could provide new signatures for stop
production at LEP.


title: Sum rules, Regge trajectories, and relativistic quark models

abstract:
  We present an analysis which uses Regge structure and the Bjorken and
Voloshin HQET sum rules to restrict the choice of parameters of a relativistic
quark model.


title: The Toroid Moment of Majorana Neutrino

abstract:
  If neutrino is the Majorana particle it can possess only one electromagnetic
characteristic, the toroid dipole moment (anapole) in the static limit and
nothing else. We have calculated the diagonal toroid moment (form factor) of
the Majorana neutrino by the dispersion method in the one-loop approximation of
the Standard Model and found it to be different from zero in the case of
massive as well as massless neutrinos. All external particles are on the mass
shells and there are no problems with the physical interpretation of the final
result. Some manifestations of the toroid interactions of Majorana neutrinos,
induced by their toroid moments, are also remarked.


title: Single Isospin Decay Amplitude and CP Violation

abstract:
  We study partial rate asymmetry in decays with single isospin final state.
For K meson or hyperon decays, the partial rate asymmetries are always zero if
the final states are single isospin states. In B decays the situation is
dramatically different and partial rate asymmetries can be non-zero even if the
final states are single isospin states. We calculated partial rate asymmetries
for several B decays with single isospin amplitude in the final states using
factorization approximation. We find that in some cases the asymmetries can be
large.


title: GUT Baryogenesis after Preheating

abstract:
  At the end of inflation the universe is frozen in a near zero-entropy state
with energy density in a coherent scalar field and must be ``defrosted'' to
produce the observed entropy and baryon number. We propose that the baryon
asymmetry is generated by the decay of supermassive Grand Unified Theory (GUT)
bosons produced non-thermally in a preheating phase after inflation. We show
that baryogenesis is possible for an inflaton masses of order 10^{13} GeV and a
GUT Higgs boson mass of order 10^{14} GeV, thus solving many drawbacks facing
GUT baryogenesis in the old reheating scenario.


title: Is SUSY accessible by direct dark matter detection?

abstract:
  We performed a combined analysis of the parameter space of the Minimal
Supersymmetric Standard Model (MSSM) taking into account cosmological and
accelerator constraints including those from the radiative $b\rightarrow
s\gamma$ decay measured by the CLEO collaboration. Special attention is paid to
the event rate, $R$, of direct dark matter neutralino detection. We have found
domains of the parameter space with $R\simeq 5-10$~events/kg/day. This would be
within the reach of current dark matter experiments. The $b\rightarrow s\gamma$
data do not essentially reduce these large event rate domains of the MSSM
parameter space.


title: Four fermion final states in $e^+e^-$ annihilation

abstract:
  The present status of calculations of four fermion final states is reviewed.
Higher order problems arising there are pointed out. Special attention is paid
to results obtained in the semi-analytical approach and their limitations and
perspectives.


title: DCC: Attractive Idea Seeks Serious Confirmation

abstract:
  The theoretical ideas relevant for the physics of the disoriented chiral
condensate (DCC) are reviewed.


title:
Baryon Magnetic Moments and Proton Spin: A Model with Collective Quark
  Rotation

abstract:
  We analyse the baryon magnetic moments in a model that relates them to the
parton spins $\Delta u$, $\Delta d$, $\Delta s$, and includes a contribution
from orbital angular momentum. The specific assumption is the existence of a
3-quark correlation (such as a flux string) that rotates with angular momentum
$\langle L_z \rangle$ around the proton spin axis. A fit to the baryon magnetic
moments, constrained by the measured values of the axial vector coupling
constants $a^{(3)}=F+D$, $a^{(8)}=3F-D$, yields $\langle S_z \rangle = 0.08 \pm
0.13$, $\langle L_z \rangle = 0.39 \pm 0.09$, where the error is a theoretical
estimate. A second fit, under slightly different assumptions, gives $\langle
L_z \rangle = 0.37 \pm 0.09$, with no constraint on $\langle S_z \rangle$. The
model provides a consistent description of axial vector couplings, magnetic
moments and the quark polarization $\langle S_z \rangle$ measured in deep
inelastic scattering. The fits suggest that a significant part of the angular
momentum of the proton may reside in a collective rotation of the constituent
quarks.


title:
Kinematical Dependence of NLO Corrections to Semi-Inclusive Spin
  Dependent Observables

abstract:
  We analyse the phenomenological consequences of target and current
fragmentation contributions at next to leading order in semi-inclusive spin
dependent deep inelastic scattering asymmetries.


title:
Nonequilibrium corrections to energy spectra of massive particles in
  expanding universe

abstract:
  Deviations from kinetic equilibrium of massive particles caused by the
universe expansion are calculated analytically in the Boltzmann approximation.
For the case of an energy independent amplitude of elastic scattering, an exact
partial differential equation is derived instead of the usual
integro-differential one. A simple perturbative solution of the former is
found. For the case of an energy-dependent amplitude the problem cannot be
reduced to the differential equation but the solution of the original
integro-differential equation can be found in terms of the Taylor expansion,
which in the case of aconstant amplitude shows a perfect agreement with the
perturbative solution of the differential equation. Corrections to the spectrum
of (possibly) massive tau-neutrinos are calculated. The method may be of more
general interest and can be applied to the calculation of spectrum distortion
in other (not necessarily cosmological) nonequilibrium processes.


title: Small $x$ behaviour of the chirally-odd parton distribution $h_1(x,Q^2)$

abstract:
  The small $x$ behaviour of the structure function $h_1(x,Q^2)$ is studied
within the leading logarithmic approximation of perturbative QCD. There are two
contributions relevant at small $x$. The leading one behaves like
$(\frac{1}{x})^0$ i.e. it is just a constant in this limit. The second
contribution, suppressed by one power of $x$, includes the terms summed by the
GLAP equation. Thus for $h_1(x,Q^2)$ the GLAP asymptotics and Regge asymptotics
are completely different, making $h_1(x,Q^2)$ quite an interesting quantity for
the study of small $x$ physics.


title:
Higgs signals and hard photons via $WW$-fusion in the Standard Model at
  the Next Linear Collider

abstract:
  Within the framework of the Standard Model, integrated and differential
distributions are given for Higgs production via the $WW$-fusion mechanism and
decay via the channels $H\ar b\bar b$ and $H\ar WW\ar {jjjj}$, with and without
photon radiation, at Next Linear Collider energies. Calculations are carried
out at tree-level and rates of the leading processes $e^+e^-\ar\bar\nu_e\nu_e H
\ar \bar\nu_e\nu_e b\bar b $ and $e^+e^-\ar\bar\nu_e\nu_e H \ar \bar\nu_e\nu_e
WW \ar \bar\nu_e\nu_e {jjjj}$ are compared to those of the next-to-leading
reactions $e^+e^-\ar\bar\nu_e\nu_e H (\gamma)\ar \bar\nu_e\nu_e b\bar b \gamma$
and $e^+e^-\ar\bar\nu_e\nu_e H (\gamma)\ar \bar\nu_e\nu_e WW (\gamma) \ar
\bar\nu_e\nu_e {jjjj}\gamma$, in the case of hard and detectable photons.
Finally, a brief discussion concerning the case of $H\ar ZZ\ar{jjjj} (\gamma)$
decays is also given.


title: $K_L \to \pi^o \nu \overline{\nu}$ in Extended Higgs Models

abstract:
  The decay $K_L\rightarrow \pi^o\nu\overline{\nu}$ is an excellent probe of
the nature of CP violation. It is almost entirely CP-violating, and hadronic
uncertainties are negligible. Experiments which hope to detect the decay are
currently being planned. We calculate the decay rate in several extensions of
the standard model Higgs sector, including the Liu-Wolfenstein two-doublet
model of spontaneous CP-violation and the Weinberg three-doublet model. In a
model with an extra doublet, with CP-violation arising from the CKM sector, the
rate can increase by up to 50\%. However, in models in which the CP violation
arises either entirely or predominantly from the Higgs sector, we find that the
decay rate is much smaller than that of the standard model, unless parameters
of the model are fine-tuned.


title: Isoscalar NN spin-orbit potential from a Skyrme model with scalar mesons

abstract:
  As a first step toward circumventing the difficulty to obtain an attractive
isospin-independent NN spin-orbit force from Skyrme-type models involving only
pions, we investigate an improved Skyrme Lagrangian that incorporates the
scalar-isoscalar meson \epsilon which can be viewed as the cause behind the
enhancement of the $\pi \pi S$-wave. We find that at large distances, the main
contribution to the spin-orbit potential comes from the scalar Lagrangian and
it is found to be attractive. We briefly discuss how to pursue this work to
finally obtain a medium-range attractive interaction.


title:
Strong supersymmetric quantum effects on top quark production at the
  Fermilab Tevatron

abstract:
  The supersymmetric QCD corrections to top quark pair production by $q\bar q$
annihilation in $p\bar p$ collisions are calculated in the minimal
supersymmetric model. We consider effects of the mixing of the scalar top
quarks on the corrections to the total $t\bar t$ production cross section at
the Fermilab Tevatron. We found that such correction is less sensitive to
squark mass and gluino mass than in no-mixing case, and in both cases the
corrections can exceed 10\% even if we consider the recent CDF limit on squark
and gluino masses.


title:
Gluon fragmentation function in polarised $\Lambda$ hyperon production:
  The Method of Factorisation

abstract:
  We discuss the polarised fragmentation functions of quarks and gluons in
Perturbative Quantum Chromodynamics. The Altarelli-Parisi evolution equations
governing these fragmentation functions are presented. We find that the first
moment of the polarised gluon fragmentation function to order $\alpha_s$ is as
important as that of the quark and anti-quark fragmentation functions. The
$\Lambda$ production in polarised $e^+ e^-$ annihilation where this can be
realised is discussed. We propose the factorisation method to compute the
gluonic contribution to $\Lambda$ production to order $\alpha_s$. With
appropriate operator definitions for the quark and the gluon fragmentation
functions, we find that the hard part of the factorisation formula is free of
any infrared singularities confirming the factorisation.


title:
Order $\alpha_s(Q^2)$ QCD corrections to the polarised $e^+~e^- \to
  \Lambda ~X$

abstract:
  The importance of polarised gluons fragmenting into $\Lambda$ in the
polarised $e^+ e^-$ annihilation is discussed using the Altarelli-Parisi
evolution equations satisfied by the quark and gluon fragmentation functions.
In this context, the polarised fragmentaion function $\hat g_1^\Lambda(x,Q^2)$
appearing in the cross section is discussed within the parton model. We relate
this fragmentation function to the quark, anti-quark and gluon fragmentation
functions and also find the QCD corrections to order $\alpha_s$.


title:
The Gluon Self-Energy in the Coulomb and Temporal Axial Gauges via the
  Pinch Technique

abstract:
  The $S$-matrix pinch technique is used to derive an effective gluon
self-energy to one-loop order, when the theory is quantized in the Coulomb
gauge (CG) and in the temporal axial gauge (TAG). When the pinch contributions
are added, the gluon self-energies calculated in CG and TAG turn out to be
identical and coincide with the result previously obtained with covariant
gauges. The issue of gauge independence of several quantities in hot QCD is
discussed from the pinch technique point of view. It is also pointed out that
the spurious singularities which appear in TAG calculations cancel out once the
pinch contributions are combined.


title: Bottom quark production cross section at HERA-B

abstract:
  The cross section for bottom quark production is calculated for the HERA-B
experiment. We consider both the order $\alpha_s^3$ cross section and the
resummation of soft gluon corrections in all orders of QCD perturbation theory.


title: Shape Variables for the Doubly-Charmed B Decays

abstract:
  We propose to use the hadronic shape variables to test the assumption of
``local duality'' in the doubly-charmed B decays, $B\rightarrow X_{c\bar c s}$.
We compute these shape variables at leading order in parton model, and discuss
how they can be compared with the experimental values.


title: Pion-Nucleon Phase Shifts in Heavy Baryon Chiral Perturbation Theory

abstract:
  We calculate the phase shifts in the pion-nucleon scattering using the heavy
baryon formalism. We consider phase shifts for the pion energy range of 140 to
$200 $ MeV. We employ two different methods for calculating the phase shifts -
the first using the full third order calculation of the pion-nucleon scattering
amplitude and the second by including the resonances $\Delta$ and $N^*$ as
explicit degrees of freedom in the Lagrangian. We compare the results of the
two methods with phase shifts extracted from fits to the pion-nucleon
scattering data. We find good to fair agreement between the calculations and
the phase shifts from scattering data.


title:
Renormalization Group Effects on the Mass Relation Predicted by the
  Standard Model with Generalized Covariant Derivatives

abstract:
  Renormalization group analysis is made on the relation $m_{\rm H} \simeq
\sqrt{2}m_t$ for masses of the top quark and the Higgs boson, which is
predicted by the standard model based on generalized covariant derivatives with
gauge and Higgs fields. This relation is a low energy manifestation of a tree
level constraint which holds among the quartic Higgs self-coupling constant and
the Yukawa coupling constants at a certain high energy scale $\mu_0$. With the
renormalization group equation at one-loop level, the evolution of the
constraint is calculated from $\mu_0$ down to the low energy region around the
observed top quark mass. The result of analysis shows that the Higgs boson mass
is in $m_t \lesssim m_{\rm H} \lesssim \sqrt{2}m_t$ for a wide range of the
energy scale $\mu_0 \gtrsim m_t$ and it approaches to 177 GeV ($\approx m_t$)
for large values of $\mu_0$.


title: The Bosonization of the Electroweak Penguin Operators

abstract:
  We give the complete $O(p^2)$ bosonization of the electroweak Penguin
operators $Q_{7,8}$ and compare the result with that of the gluon Penguin
operators $Q_{5,6}$. We find that, in addition to the usual (constant and
current-current) parts, there are three new terms not discussed previously in
the literature. Two of these are present in the factorization approximation and
should be included in the standard definition of the $B_{7,8}$-factors. The
impact of these corrections on the direct $CP$-violating parameter $\varepsilon
'/\varepsilon$ is briefly discussed.


title: Diffractive Leptoproduction of Small Masses in QCD

abstract:
  In this paper we consider the process of diffraction dissociation in deep
inelastic scattering producing a small mass. This process is analyzed by the
calculation of $\bar q\, q$ and $\bar q\, q\, G$ production. We show that the
small distance contributions ($r_{\perp}\,\propto\,1/Q$) to the longitudinal
polarised virtual photon dominate the diffractive channels. Formulae for the
cross section using the gluon density are written within the framework of
perturbative QCD. We show that the production of small masses by a transverse
polarised photon is concentrated at moderate values of $r_{\perp} \,\sim\,1
GeV^{-1}$, where the pQCD approach is valid. It is shown that only $\bar q\, q$
pair production contributes to diffraction dissociation with $\b\,>\,$ 0.4 and
the possibility to extract the values of the gluon density from the
measurements in this kinematic region is discussed. Shadowing corrections are
assessed for both longitudinal and transverse polarised photons and estimates
of the different damping factors are given. The relation between diffractive
production and the corrections to $F_2$ is alluded to. The evolution of the
diffractive structure function is studied and a solution to the difractive
evolution equations is proposed.


title: Little Miracles of Supersymmetric Evolution of Gauge Couplings

abstract:
  The invention of supersymmetry, almost exactly 25 years ago, changed the face
of high-energy physics. The idea that the observed low-energy gauge groups
appear due to the process of spontaneous breaking of a single unifying group
$G$ is also quite popular. The synthesis of these two elements results in
supersymmetric grand unification. I present (perturbatively) exact results
regarding the supersymmetric evolution of the gauge couplings from the scale of
their unification to lower scales. In particular, it is shown how the heavy
mass thresholds can be properly taken into account to all orders.


title: Explicit CP Breaking and Electroweak Baryogenesis

abstract:
  We investigate spatial behaviors of the CP-violating angle $\theta$ by
solving the equation of motion of the two-Higgs-doublet model in the presence
of a small explicit CP breaking $\delta$. The moduli of the two Higgs scalars
are fixed to be the kink shape with a common width. In addition to solutions
$\theta \sim O(\delta)$ in all the region, we find several sets of two
solutions of opposite signs, whose magnitudes become as large as $O(1)$ around
the surface of the bubble wall while the CP violation in the broken phase limit
is of $O(\delta)$. Such set of solutions not only yield sufficient amount of
the chiral charge flux, but also avoid the cancellation in the net baryon
number because of a large discrepancy in their energy densities driven
nonperturbatively by the small $\delta$.


title: Parity Doubles in Quark Physics

abstract:
  There are numerous examples of very nearly degenerate states of opposite
parity in molecular physics. The ammonia maser is based on one such double.
Theory shows that these parity doubles can occur if the nuclear shape in the
molecule is reflection-asymmetric because the time scales of the shape and the
electronic cloud are well-separated. Parity doubles occur in nuclear physics as
well for odd $A \sim 219-229$. We discuss the theoretical foundation of these
doubles and on that basis suggest that parity doubles should occur in particle
physics too. In particular they should occur among baryons composed of $cbu$
and $cbd$ quarks.


title:
Passage of charmed particles through the mixed phase in high-energy
  heavy-ion collisions

abstract:
  We employ a modified cascade hydrodynamics code to simulate the phase
transition of an expanding quark-gluon plasma and the passage of a charmed
particle through it. When inside the plasma droplets, the charmed quark
experiences drag and diffusion forces. When outside the plasma, the quark
travels as a $D$ meson and experiences collisions with pions. Additional energy
transfer takes place when the quark enters or leaves a droplet. We find that
the transverse momentum of $D$ mesons provides a rough thermometer of the phase
transition.


title:
Weak long distance contributions to the neutron and proton electric
  dipole moments

abstract:
  We evaluate the long distance weak contribution to the neutron and proton
electric dipole moments using an effective Lagrangian framework. We estimate
the coefficients needed by a factorization hypothesis and additional
assumptions on $\gamma_5$ terms in the baryon lagrangian. We obtain
$|d_e^n|\approx 5\times 10^{-32}$ e$\cdot$cm and $|d_e^p|\approx 4\times
10^{-32}$ e$\cdot$cm. The former estimate is similar to the quark model
estimates done previously.


title: The mass of the scalar boson beyond the large-N_c limit

abstract:
  Within the framework of the $1/N_c$ expansion of four-fermion interaction
models, we analyse the next to leading $1/N_c$ corrections to the well known
large-$N_c$ result $M_S=2M_Q$ where $M_S$ is the mass of the scalar boson and
$M_Q$ is the constituent quark mass. The calculation is performed in the
Extended Nambu-Jona Lasinio (ENJL) model which is suitable for describing low
energy hadron properties. We treat the model as fully non renormalizable and
discuss the comparison with approaches based on the equivalence with
renormalizable Yukawa type models. We consider both the $G_V=0$ and the
$G_V\neq 0$ cases with $n_f=2$ flavours and study the dependence upon the
regularization scheme. We find that pure next-to-leading $1/N_c$ corrections
are large and negative, while a partially resummed treatment can induce
positive and smaller corrections. A triplet-singlet states' splitting is
observed.


title: Is factorization for isolated photon cross sections broken?

abstract:
  Recently the factorization property has been claimed to be broken in the
cross section for the production of isolated prompt photons emitted in the
final state of hadronic $e^ + e^-$ annihilation. We contest this claim.


title: Two-Loop Corrections to Fermion Pair Production Vertices

abstract:
  Recent results on the entirely analytic calculation of second order
corrections to massive quark pair production vertices induced by light quark
flavours are reviewed. Based on the method presented in this talk the second
order effects of the insertion of any massless one-loop vacuum polarization
into the gluon line of the first order diagrams can be determined. The
behaviour of the corrections at threshold for vector and axial-vector current
induced massive quark production is discussed.


title:
J/Psi Suppression in Pb-Pb Collisions: A Hint of Quark-Gluon Plasma
  Production?

abstract:
  The NA50 Collaboration has recently observed a strong suppression of J/Psi
production in Pb-Pb collisions at 158 Gev/n. We show that this recent
observation finds a quantitative explanation in a model which relates the
suppression mechanism to the local energy density, whose value is higher in
Pb-Pb collisions than in any other system studied previously. The sensitivity
of the phenomenon to small changes in the energy density could be suggestive of
quark-gluon plasma formation.


title: SUSY-QCD corrections in the squark-gluino sector

abstract:
  A status report is given of the calculations of next-to-leading-order ($N=1$)
supersymmetric QCD corrections to the production of squarks and gluinos in
$p\bar{p}/pp$ collisions. The implementation of these SUSY-QCD corrections
leads to more stable theoretical predictions and to a substantial increase of
the production cross-sections. In addition we give a discussion of the use of
the $\overline{MS}$ scheme for renormalizing the coupling constants in the QCD
sector of ($N=1$) supersymmetric theories.


title: Neutralino mass bounds at the upgraded LEP collider

abstract:
  Assuming that no supersymmetric signature will be found at the upgraded LEP
collider we derive lower bounds on the masses of the four neutralinos
$\tilde{\chi}_i^0$ in the Minimal Supersymmetric Standard Model (MSSM). We
consider the recently published results from the search for the light chargino
$\tilde{\chi}^\pm_1$ and the next-to-lightest neutralino $\tilde{\chi}^0_2$ at
LEP1.5 and study the consequences of possible future lower $\tilde{\chi}^\pm_1$
and $\tilde{\chi}^0_2$ mass limits between 65 and 95 GeV. For a chargino mass
bound of 66.8 GeV at LEP1.5, a massless neutralino is not excluded for
$\tan\beta < 1.2$. If either $\tan\beta > 2.3$ or the gluino mass
$m_{\tilde{g}} > 160$ GeV, we find $m_{\tilde{\chi}_1^0} > 28$ GeV. A possible
chargino bound $m_{\tilde{\chi}_1^\pm} > 95$ GeV at LEP2 would raise this bound
to 31 GeV (for all $\tan\beta$) or 44 GeV ($\tan\beta > 2$).


title: The dual gauge fixing property of the S matrix

abstract:
  The $S$-matrix is known to be independent of the gauge fixing parameter to
all orders in perturbation theory. In this paper by employing the pinch
technique we prove at one loop a stronger version of this independence. In
particular we show that one can use a gauge fixing parameter for the gauge
bosons inside quantum loops which is different from that used for the bosons
outside loops, and the $S$-matrix is independent from both. Possible
phenomenological applications of this result are briefly discussed.


title: Further analysis of the BFKL equation with momentum cutoffs

abstract:
  In this paper we investigate the effect of introducing transverse momentum
cutoffs on the BFKL equation. We present solutions in moment space for various
models of the BFKL kernel for different combinations of these cutoffs. We
improve on previous calculations by using the full BFKL kernel (rather than
simplified analytic approximations). The significance of the next-to-leading or
``higher twist'' terms in the kernel are assessed. We find that, while these
terms are negligible in the absence of cutoffs, introducing an infra-red cutoff
markedly enhances their significance.


title: Properties of HERA Events from DIS on Pions in the Proton

abstract:
  Recently the concept of the pion cloud in the nucleon turned out to be
successful in understanding the Gottfried sum rule violation observed by the
New Muon Collaboration and the Drell--Yan asymmetry measured in NA51 at CERN.
We propose a further possibility to test this concept at HERA through the
analysis of the structure of deep inelastic scattering (DIS) events induced by
pion--exchange. Momentum and energy distributions of outgoing nucleons as well
as rapidity and multiplicity distributions are investigated using Monte Carlo
simulations. Most observables cannot distinguish this process from ordinary
DIS, but in the energy distribution of final neutrons we find a significantly
different prediction from the pion cloud model. Forward neutron calorimeters
will be essential to test the concept of pions in the nucleon.


title: Neutrino Propagation in a Fluctuating Sun

abstract:
  We adapt to neutrino physics a general formulation for particle propagation
in fluctuating media, initially developed for applications to electromagnetism
and neutron optics. In leading approximation this formalism leads to the usual
MSW effective hamiltonian governing neutrino propagation through a medium.
Next-to-leading contributions describe deviations from this description, which
arise due to neutrino interactions with fluctuations in the medium. We compute
these corrections for two types of fluctuations: ($i$) microscopic thermal
fluctuations, and ($ii$) macroscopic fluctuations in the medium's density.
While the first of these reproduces standard estimates, which are negligible
for applications to solar neutrinos, we find the second can be quite large,
since it grows in size with the correlation length of the fluctuation. We
consider two models in some detail. For fluctuations whose correlations are
extend only over a local region in space of length $l$, appreciable effects for
MSW oscillations arise if $(\delta n/n)^2 l\gsim 100$ m or so. Alternatively, a
crude model of helioseismic $p$-waves gives appreciable effects only when
$(\delta n/n) \gsim 1%$.
  In general the dominant effect is to diminish the quality of the resonance,
making the suppression of the ${}^7$Be neutrinos a good experimental probe of
fluctuations deep within the sun. Fluctuations can also provide a new mechanism
for reducing the solar neutrino flux, giving an energy-independent suppression
factor of $1/2$, away from the resonant region, even for small vacuum mixing
angles.


title: Unified Description of Kaon Electroweak Form Factors

abstract:
  A calculation of the semi--leptonic decays of the kaon ($K_{l3}$) is
presented. The results are direct predictions of a covariant model of the pion
and kaon introduced earlier by Ito, Buck, Gross. The weak form factors for
$K_{l3}$ are predicted with absolutely no parameter adjustments of the model.
We obtained for the form factor parameters:
$f_-(q^2=m_l^2)/f_+(q^2=m_l^2)=-0.28$ and $\lambda_+$= 0.028, both within
experimental error bars. Connections of this approach to heavy quark symmetry
will also be discussed.


title: Initial Conditions for Smooth Hybrid Inflation

abstract:
  We perform a numerical investigation of the field evolution in the smooth
hybrid inflationary model. We find that for almost all the examined initial
values we do get an adequate amount of inflation. Our results show that the
model is ''natural'' and satisfactory.


title: Dyon mass bounds from electric dipole moments

abstract:
  Dyon loops give a contribution to the matrix element for light-by-light
scattering that violates parity and time-reversal symmetry. This effect induces
an electric dipole moment for the electron, of order $M^{-2}$, where $M$ is the
dyon mass. The current limit on the electric dipole moment of the electron
yields the lower mass bound $M>{\cal O}(1)~\mbox{TeV}$.


title: Effective Theory for Heavy Quarks

abstract:
  In this series of lectures the basic ideas of the $1/m_Q$ expansion in QCD
($m_Q$ is the mass of a heavy quark) are outlined. Applications to exclusive
and inclusive decays are given.


title: Radiative corrections to $e^+e^-\to H^+ H^-$

abstract:
  We study the 1-loop corrections to the charged Higgs production both in the
Minimal Supersymmetric Standard Model (MSSM) and in a more general type II
two-Higgs-doublet model (THDM-II). We consider the full set of corrections
(including soft photon contributions as well as box diagrams), and define a
parametrization that allows a comparison between the two models. Besides the
soft photon radiation there can be prominent model-dependent effects.


title: The Standard Model at Low Energies

abstract:
  These are short proceedings of the workshop on ``The Standard Model at Low
Energies'' held at ECT* in Trento, Italy, from April 29 to May 10, 1996. The
workshop concentrated on Chiral Perturbation Theory in its various settings.
Included are a one page contribution with references per speaker and a listing
of some review papers of relevance to the field.


title: Baryogenesis with vector-like quark model in charge transport mechanism

abstract:
  The electroweak baryogenesis is studied in the charge transport mechanism
with the vector-like quark model. Introducing an extra vector-like up-type
quark and a singlet Higgs scalar with the mass of the order of a few hundred
GeV, the baryon number generation from the bubble wall is estimated. We show
that this scenario is consistent with the measurement of the present baryon to
entropy ratio of our universe, if the parameters are in the right region.


title: Compton Scattering on Black Body Photons

abstract:
  We examine Compton scattering of electrons on black body photons in the case
where the electrons are highly relativistic, but the center of mass energy is
small in comparison with the electron mass. We derive the partial lifetime of
electrons in the LEP accelerator due to this form of scattering in the vacuum
beam pipe and compare it with previous results.


title:
Medium Effects on the CP phases and Dynamical Mixing Angles in the
  Neutrino Mixing Matrix

abstract:
  The concepts of effective and dynamical neutrino mixing matrices are
introduced in order to describe the behavior of neutrinos in matter. The former
relates weak eigenstates to mass eigenstates, whereas the latter relates weak
eigenstates to energy eigenstates in matter. It is shown that the dynamical
mixing angles enable us to express the neutrino survival probability in the Sun
without any resort to the Landau-Zener transition probability for the
non-adiabatic process. Also discussed are effective CP violating phases that
appear in the effective and dynamical mixing matrices in matter. Both two and
three generation cases are discussed using the solar neutrinos as an example.


title: Thermal and chemical equilibration in a gluon plasma

abstract:
  We show the evolution of a gluon plasma towards equilibrium starting at some
early moment when the momentum distribution in the central region is
momentaneously isotropic. Using HIJING results for Au+Au collision as initial
input, we consider thermalization and chemical equilibration simultaneously at
both LHC and RHIC energies. Thermalization is shown to be driven chiefly by
inelastic process in our scenario contradicting common assumption that this is
the role of elastic process. We argue that only the inelastic dominancy depends
on the initial conditions but not the dominance itself.


title:
On Electro-weak mixing derived from radiative corrections and the
  necessity of the Higgs mechanism

abstract:
  Starting from the unmixed Lagrangian, the electro-weak radiative corrections
are recomputed using symmetrical generalised functions. All gauge bosons
acquire an indeterminate mass. Electro-weak mixing is obtained by
diagonalization of the mass matrix. The W/Z mass ratio follows automatically.
The Higgs mechanism is not needed to generate the vector boson masses. A mass
sum rule is postulated to obtain a zero photon mass. The radiative corrections
are different, and (provisionally) in agreement with experiment, when the no
longer needed Higgs terms are omitted.


title: The pomeron-pomeron interaction in the perturbative QCD

abstract:
  The pomeron-pomeron interaction is studied in the perturbative approach of
BFKL-Bartels. The total pomeron-pomeron cross-section is proportional to
$\alpha_{s}^{4}s^{\Delta}/\sqrt {t_{1}t_{2}}$ where $\sqrt{s}$ is the c.m.
energy and $t_{1,2}$ are the virtualities of the colliding pomerons. Upon
calculating the coefficient the cross-section is found to be of the order 2.2
mb at $\sqrt{s}= 6$ TeV and $\sqrt{-t_{1}}\sim\sqrt{-t_{2}}\sim 1$ GeV/c.


title:
Leptonic Custodial Symmetry, Quantization of the Electric Charge and the
  Neutrino in the Standard Model

abstract:
  I study, in the leptonic sector, the role of the $SU(2)_V$ custodial symmetry
$\ti{\cal G}$ which was shown in ref. [1] to control the quantization of the
electric charge in the $J=0$ mesonic sector. The electroweak theory is
considered, according to ref. [2], as a purely vectorial model which interacts
with a ``hidden'' sector of composite scalars. $\ti{\cal G}$ can only be a
symmetry of the former if the neutrino is a Majorana particle; the latter
provides a dynamical modification of the leptonic weak couplings,
reconstructing those of the Standard Model with a massless Majorana neutrino.