title: Jets in photon-photon collisions: from TRISTAN to J/N-LC

abstract:
  We study jet production in photon-photon reactions at the next-to-leading
logarithm accuracy. Special emphasis is placed on the discussion of the
theoretical uncertainties and on the role of the hadronic component of the
photon structure function. We also discuss subtleties in the quasi-real photon
spectrum when the photon is involved in a large transverse momentum reaction.
The phenomenology at TRISTAN energies is discussed and predictions are made for
LEP and a $1\ TeV$ \epem collider.


title: Mass Dependent $\alpha_S$ Evolution and the Light Gluino Existence

abstract:
  There is an intriguing discrepancy between \alpha_s(M_Z) values measured
directly at the CERN $Z_0$-factory and low-energy (at few GeV) measurements
transformed to $Q=M_{Z_0}$ by a massless QCD \alpha_s(Q) evolution relation.
There exists an attempt to reconcile this discrepancy by introducing a light
gluino $\gl$ in the MSSM.
  We study in detail the influence of heavy thresholds on \alpha_s(Q)
evolution. First, we consruct the "exact" explicit solution to the
mass-dependent two-loop RG equation for the running \alpha_s(Q). This solution
describes heavy thresholds smoothly. Second, we use this solution to
recalculate anew \alpha_s(M_Z) values corresponding to "low-energy" input data.
Our analysis demonstrates that using {\it mass-dependent RG procedure}
generally produces corrections of two types: Asymptotic correction due to
effective shift of threshold position; Local threshold correction only for the
case when input experiment lies in the close vicinity of heavy particle
threshold: $Q_{expt} \simeq M_h $.
  Both effects result in the effective shift of the \asmz values of the order
of $10^{-3}$. However, the second one could be enhanced when the gluino mass is
close to a heavy quark mass. For such a case the sum effect could be important
for the discussion of the light gluino existence as it further changes the
$\gl$ mass.


title:
Possible constraints on SUSY-model Parameters from Direct Dark Matter
  Search

abstract:
  We consider the SUSY-model neutralino as a dominant Dark Matter particle in
the galactic halo and investigate some general issues of direct DM searches via
elastic neutralino-nucleus scattering.
  On the basis of conventional assumptions about the nuclear and nucleon
structure, without referring to a specific SUSY-model, we prove that it is
impossible in principle to extract more than three constraints on fundamental
SUSY-model parameters from the direct Dark matter searches.
  Three types of Dark matter detectors probing different groups of parameters
are recognized.


title: $SU(4)_L \otimes U(1)_N$ model for the electroweak interactions

abstract:
  Assuming the existence of right-handed neutrinos, we consider an electroweak
model based on the gauge symmetry $SU(4)_L\otimes U(1)_N$. We study the neutral
currents coupled to all neutral vector bosons present in the theory. There are
no flavor changing neutral currents at tree level, coupled with the lightest
neutral vector boson.


title:
Long-Distance Contributions to the
  $\Lambda_b\rightarrow\Lambda_ce^-\overline{\nu}_e$ Isgur-Wise Function

abstract:
  The six independent formfactors describing the weak decay \semi\ are
determined in terms of one universal function when both the $b$ and $c$ quarks
are treated as heavy. The relations between these formfactors are modified by
terms suppressed by inverse powers of the charm quark mass. We compute the
formally leading long-distance corrections to these relations in chiral
perturbation theory both at and away from zero recoil. They arise from the
spin-symmetry breaking $\Sigma_c^* - \Sigma_c$ mass splitting and are
nonanalytic in the pion mass. The correction at the zero-recoil point is found
to be $ - (3.4 \pm 2.0) \times 10^{-4} g_3^2$ for a quark model estimate of
$m_{\Sigma_c^*}-m_{\Sigma_c}$ and where $g_3\sim 1$ is an axial coupling
constant. Further, the formfactors that vanish in the heavy quark limit do not
receive such corrections.


title: General Analysis of Phases in Quark Mass Matrices

abstract:
  We give a detailed discussion of our general determination of (i) the number
of unremovable, physically meaningful phases in quark mass matrices and (ii)
which elements of these matrices can be rendered real by rephasings of fermion
fields. The results are applied to several currently viable models. New results
are presented for an arbitrary number of fermion generations; these provide
further insight into the three-generation case of physical interest.


title: Neutrino Phenomenology from Unconventional E$_6$ models

abstract:
  Superstring derived $\E$ models can accommodate small neutrino masses if a
discrete symmetry is imposed which forbids tree level Dirac neutrino masses but
allows for radiative mass generation. The only possible symmetries of this kind
are known to be generation dependent. We explore the possibility that, as a
consequence of such a symmetry, the three sets of light states in each
generation do not have the same assignments with respect to the {\bf 27} of
$E_6$, implying that the gauge interactions under the additional $U(1)^\pr$
factors are non universal. Models realising such a scenario are found to be
viable, and by requiring the number of light neutral states to be minimal, an
almost unique pattern of neutrino masses and mixings arises. We briefly discuss
a model in which, with a natural choice of the parameters, $m_{\nu_\tau}\sim
0.1-10\,$eV is generated at one loop, $m_{\nu_\mu} \sim 10^{-3}\,$eV is
generated at two loops and ${\nu_e}$ remains massless.


title: Strong and Electromagnetic Decays of Two New $Lambda_c^*$ Baryons

abstract:
  Two recently discovered excited charm baryons are studied within the
framework of Heavy Hadron Chiral Perturbation Theory. We interpret these new
baryons which lie $308 \MeV$ and $340 \MeV$ above the $\Lambda_c$ as $I=0$
members of a P-wave spin doublet. Differential and total decay rates for their
double pion transitions down to the $\Lambda_c$ ground state are calculated.
Estimates for their radiative decay rates are also discussed. We find that the
experimentally determined characteristics of the $\Lambda_c^*$ baryons may be
simply understood in the effective theory.


title: Exclusive Radiative B-Decays in the Light-Cone QCD Sum Rule Approach

abstract:
  We carry out a detailed study of exclusive radiative rare $B$-decays in the
framework of the QCD sum rules on the light cone, which combines the
traditional QCD sum rule technique with the description of final state vector
mesons in terms of the light-cone wave functions of increasing twist. The
decays considered are: $B_{u,d} \to K^* +\gamma, B_{u,d}\to \rho+\gamma, B_d\to
\omega+\gamma$ and the corresponding decays of the $B_s$ mesons, $B_s\to
\phi+\gamma$ and $B_s\to K^*+\gamma$. Based on our estimate of the transition
form factor $F_1^{B \to K^*\pg}(0) =0.32\pm0.05$, we find for the branching
ratio $BR(B \to K^* + \gamma) = (4.8\pm 1.5)\times 10^{-5}$, which is in
agreement with the observed value measured by the CLEO collaboration. We
present detailed estimates for the ratios of the radiative decay form factors,
which are then used to predict the rates for the exclusive radiative B-decays
listed above. This in principle allows the extraction of the CKM matrix element
$|V_{td}|$ from the penguin-dominated CKM-suppressed radiative decays when they
are measured. We give a detailed discussion of the dependence of the form
factors on the $b$-quark mass and on the momentum transfer, as well as their
interrelation with the CKM-suppressed semileptonic decay form factors in $B\to
\rho+\ell+\nu$, which we also calculate in our approach.


title:
The Nonperturbative Wave Functions, Transverse Momentum Distribution and
  QCD Vacuum Structure

abstract:
  It is shown that there is one-to-one correspondence between two, apparently
different problems: \\ 1. The determination of the meanvalues of transverse
moments $\la \vec{k}_{\perp}^{2n} \ra $ for the nonperturbative pion wave
function $\psi(\k, x)$ and \\ 2. The evaluation of the mixed vacuum condensates
$ \la \bar{q}G_{\mu\nu}^n q\ra $. eneral properties of the theory. We define
and model $\psi(\k, x)$, satisfying all these constraints.


title: pbarp partial wave analysis and NbarN potentials

abstract:
  Invited talk given at the NAN '93 Conference in Moscow, Russia, sept 1993. A
review is given of the different ways to describe pbarp scattering. Next the
Nijmegen partial wave analyses of the pbarp data as well as the corresponding
Nijmegen NbarN database are discussed. These partial wave analyses are finally
used as a tool to construct a better NbarN potential model and also to clarify
questions raised in the literature.


title: Relativistic Quark Model Based Description of Low Energy NN Scattering

abstract:
  A description of the NN scattering is constructed starting from the $\pi,
\eta, \eta'$ pseudoscalar-, the $\rho, \phi, \omega$ vector-, and the
$\varepsilon(600), a_0, f_0(1400)$ scalar - meson-nucleon coupling constants,
which we obtain within a relativistic quark model. Working within the
Blankenbecler-Sugar-Logunov-Tavkhelidze quasipotential dynamics we thus
describe the NN phase shifts in a relativistically invariant way. In this
procedure we use the phenomenological form factor cutoff masses and the
effective $\varepsilon$ and $\omega$ meson-nucleon coupling constants, only.
The comparison of our NN phase shifts to the both empirical data and the Bonn
OBEP fit shows good agreement -- the ratio of the $\chi^2$ for the present
results to the $\chi^2$ for Bonn OBEP description is 1.2.


title: Baryonic and Gluonic Correlators in Hot QCD

abstract:
  We extend our earlier work on static color singlet correlators in high T QCD
(DeTar correlators) to baryonic and gluonic sources, and estimate the
corresponding screening masses using the dimensionally reduced theory. We
discuss spin and polarization dependence of meson and baryon masses in the $T
\rightarrow \infty$ limit, and possible nonperturbative effects at
non-asymptotic temperatures.


title:
One loop calculations on the Wess-Zumino-Witten anomalous functional at
  finite temperature

abstract:
  We analyze the finite temperature (T) extension of the Wess-Zumino- Witten
functional, discussed in a previous work, to one loop in chiral perturbation
theory. As a phenomenological application, we calculate finite temperature
corrections to the amplitude of the $\pi^0$ decay into two photons. This
calculation is performed in three limits : i)$T/M_{\pi}<<1$, ii)the chiral
limit at finite T and iii)$T/M_{\pi}>>1$ ($M_{\pi}$ being the pion mass). The
$T$-corrections tend to vanish in the chiral limit, where only the kaon
contribution remains (although it is exponentially suppressed).


title: Hadron Radiation in Leptonic $Z$ Decays

abstract:
  The rate for the final state radiation of hadrons in leptonic $Z$ decays is
evaluated, using as input experimental data for $\sigma (e^+e^-\to hadrons)$ in
the low energy region. Configurations with a lepton pair of large and a
hadronic state of low invariant mass are dominant. A relative rate
$\Gamma_{l\bar l had}/\Gamma_{l\bar l}=6.3\times 10^{-4}$ is calculated. This
result is about twice the prediction based on a parton model calculation with a
quark mass of $300$ MeV. The rate for secondary production of heavy quarks is
calculated in the same formalism.


title:
On the temperature dependence of correlation functions in the space like
  direction in hot QCD

abstract:
  We study the temperature dependence of quark antiquark correlations in the
space like direction. In particular, we predict the temperature dependence of
space like Bethe-Salpeter amplitudes using recent Lattice gauge data for the
space like string potential. We also investigate the effect of the space like
string potential on the screening mass and discuss possible corrections which
may arise when working with point sources.


title:
Quark-Induced Correlations between Instantons Drive the Chiral Phase
  Transition

abstract:
  A simple model for the instanton ensemble at finite temperature T is
proposed, including ``random" and strongly correlated ``molecular" component.
  T-dependence of fermionic zero modes naturally leads to chiral symmetry
restoration, without instanton suppression. Moreover, at $T=(1-2) T_c$ the
non-perturbative effects due to ``molecules" are so strong, that they even
dominate the global thermodynamics. % two figures are enclosed as .ps files


title:
The Nonperturbative Equation for the Infrared \Pi_{44}(0) - Limit in the
  Temporal Axial Gauge

abstract:
  The nonperturbative equation for the infrared $\Pi_{44}(0)$-limit is built by
using the Slavnov-Taylor identity to define the three-gluon vertex function in
the temporal axial gauge. We found that all vertex corrections should be taken
into account along with the standard ring graphs to keep the gauge covariance
throughout calculations and to give correctly the nonperturbative $g^3$-term.
This term is explicitly calculated and compared with the previously known
results.


title: Cluster Production in Quark-Hadron Phase Transition

abstract:
  The problem of cluster formation and growth in first-order quark-hadron phase
transition in heavy-ion collisions is considered. Behaving as Brownian
particles, the clusters carry out random walks and can encounter one another,
leading to coalescence and breakup. A simulation of the process in cellular
automaton suggests the possibility of a scaling distribution in the cluster
sizes. The experimental determination of the cluster-size distribution is urged
as a means to find a clear signature of phase transition.


title: Semileptonic and Exclusive Rare B Decays

abstract:
  The exclusive rare decay $B \ra K^\ast \gamma$ takes place in a region of
maximum recoil, $q^{2}=0$, posing a problem for nonrelativistic quark models
which are usually thought to be most reliable at zero recoil. The
Bauer--Stech--Wirbel (BSW) model, formulated in the infinite--momentum--frame
(IMF) formalism, is designed to work at $q^2=0$. We show in this model that the
ratio relating the decay $B \ra K^\ast \gamma$ and the $q^2$--spectrum of the
semileptonic decay $B\ra \rho e {\bar \nu}$, becomes independent of the wave
function in the SU(3) flavor symmetry limit. We show that this feature is also
true in relativistic quark models formulated in the IMF or light--cone
formalism, if the $b$ quark is infinitely heavy. In fact, these relativistic
models, which have a different spin structure from the BSW case, reduce to the
BSW model in the heavy $b$--quark limit. A direct measurement of the
$q^2$--spectrum of the semileptonic decay can therefore provide accurate
information for the exclusive rare decay.


title: Hadronic Wave Functions in the Instanton Model

abstract:
  We study hadronic wave functions using an instanton model for the QCD vacuum.
The wave functions are defined in terms of gauge invariant Bethe Salpeter
amplitudes which we have determined numerically using a Monte Carlo simulation
of the instanton ensemble. We find that the pion and the proton, as well as the
rho meson and the delta have very similar wave functions but observe a sizeable
splitting between mesons or baryons with different spin. We compare our results
with data obtained in lattice gauge simulations.


title: Grand unification for mirror fermions

abstract:
  The possibility of grand unification of the standard model (SM) with fermion
spectrum extended to include mirror fermions is examined. SM gauge couplings do
not automatically unify. SO(10) grand unification is studied with one
intermediate scale. Renormalization group equations (RGE) for fermion Yukawa
couplings and the scalar self-coupling are studied numerically at one and two
loop level. Strong restrictions for mirror fermion masses are obtained assuming
perturbative unification. Mirror masses much smaller than the tree unitarity
bounds are required. In particular mirror leptons have to be around 50 GeV.
Consistency of the mirror fermion model with LEP precision data is established.
A direct search for single production of mirror neutrinos at LEP could exclude
or confirm the GUT version of the mirror fermion model.


title: Do Deep Inelastic Scattering Data Favor a Light Gluino

abstract:
  A next--to--leading order QCD analysis of deep inelastic scattering data is
performed allowing for contributions due to a light gluino. We obtain the
values of $\alpha_s(M_Z^2) \pm \delta \alpha_s^{stat} = 0.108 \pm 0.002, 0.124
\pm 0.001, 0.145 \pm 0.009$ for QCD, SUSY QCD with a Majorana gluino and a
Dirac gluino respectively. The value of $\alsm$ obtained in SUSY QCD with a
Majorana gluino best agrees with the direct measurements of $\alpha_s(M_Z^2)$
at LEP.


title: Transfer matrix method and intermittency generating dynamics

abstract:
  A transfer matrix method relating the process of refinement of a fractal
measure to thermodynamic formalism of an appropriate Ising model is applied to
the analysis of intermittency in hadron collisions revealing that underlying
dynamics is that of period doublings.


title:
Comment on "Analytic Solution of the Relativistic Coulomb Problem for a
  Spinless Salpeter Equation"

abstract:
  We demonstrate that the analytic solution for the set of energy eigenvalues
of the semi-relativistic Coulomb problem reported by B. and L. Durand is in
clear conflict with an upper bound on the ground-state energy level derived by
some straightforward variational procedure.


title:
Singular terms of helicity amplitudes at one-loop in QCD and the soft
  limit of the cross sections of multi-parton processes

abstract:
  We describe a general method that enables us to obtain all the singular terms
of helicity amplitudes of n-parton processes at one loop. The algorithm uses
helicity amplitudes at tree level and simple color algebra.
  We illustrate the method by calculating the singular part of the one loop
helicity amplitudes of all $ 2\to 3$ parton subprocesses. The results are used
to derive the soft gluon limit of the cross sections of all $2\to 4$ parton
scattering subprocesses which provide a useful initial condition for the
angular ordering approximation to coherent multiple soft gluon emission,
incorporated in existing Monte Carlo simulation programs.


title: Singe Top Production at LEP 200

abstract:
  We present exact tree level cross sections for the single top production
process $e^- e^+ \rightarrow e^- \bar{\nu}_e t \bar{b} $ at LEP~200. The
results reproduce roughly those obtained earlier by using the equivalent real
photon approximation and we confirm the observation that detecting a top
heavier than half the c.m.~energy is not feasible at LEP~200. The calculation
has been performed by a new automatic Feynman amplitude generator MadGraph
which produces HELAS code for the helicity amplitudes.


title: Rapidity Gap in Jet Events at Lep200

abstract:
  We analyze various perturbative mechanisms for the production of jet events
containing rapidity gaps in $e^+e^-$ annihilation at LEP200 energies. We found
that the processes $e^+e^- \to \gamma^* \gamma^*, \gamma^* Z, Z Z, WW \to 4~
jets$ generate gap events at an observable rate. We point out that LEP200
offers a unique opportunity for the study of gap events due to a smaller
background of ``fake-gaps".


title:
Intermediate mass Higgs bosons at TeV $e\gamma$ colliders in the ${\cal
  {MSSM}}$

abstract:
  We study the cross sections for the production of intermediate mass Higgs
bosons via the reactions $e^-\gamma\rightarrow \nu_eW^-\Phi^0$,
$e^-\gamma\rightarrow \nu_eH^-\Phi^0$, $e^-\gamma\rightarrow e^-Z^0\Phi^0$ and
$e^-\gamma\rightarrow e^-H^+H^-$ in the Minimal Supersymmetric Standard Model
(with $\Phi^0=H^0,h^0$ and, where possible, $A^0$) at TeV energies, taking into
account $b$--tagging capabilities. We find that the rates for
$e^-\gamma\rightarrow \nu_eW^-\Phi^0$ are large enough to permit the discovery
of at least one between $h^0$ and $H^0$ over the whole intermediate mass range
of $M_{A^0}$, at all $\tan\beta$, using the $(jj)(b\bar b)$ final state. The
${\cal {CP}}$-odd neutral $A^0$ and the charged $H^\pm$'s can be detected via
the processes $e^-\gamma\rightarrow \nu_eH^-A^0$, with $A^0\rightarrow b\bar
b$, and $e^-\gamma\rightarrow e^-H^+H^-$, resorting to the leptonic decay
$H^\pm\rightarrow \nu_\tau\tau^+(\bar\nu_\tau\tau^-)$, but only for
$M_{A^0}\approx60$ GeV. Finally, we present explicit formulae for the helicity
amplitudes of these processes.


title: Non-Leptonic Decays of Beauty Hadrons -- from Phenomenology to Theory

abstract:
  `Anyone who keeps the ability to see beauty never grows old' Franz Kafka.
  In the last few years considerable progress has been achieved in our
understanding of the decays of heavy flavour hadrons. One can now calculate
inclusive transition rates in QCD proper through an expansion in inverse powers
of the heavy flavour quark mass without recourse to phenomenological
assumptions. The non-perturbative contributions are treated systematically in
this way; they are found to produce corrections of order a few percent in
beauty decays, i.e. typically somewhat smaller than the perturbative
corrections. One finds, among other things: (a) The lifetime of $B^-$ mesons is
predicted to be longer than that of $B^0$ mesons by several percent. (b) The
QCD prediction for the semileptonic branching ratio of $B$ mesons appears to
exceed present experimental values. We discuss the implications of this
discrepancy. The phenomenological engineering that has been developed for the
description of {\em exclusive} two-body modes of $B$ mesons has reached a
mature stage and awaits more precise and detailed experimental tests. First
steps towards a genuine QCD treatment of these modes are being made.


title: Optimized Variables of the Study of $\Lambda_b$ Polarization

abstract:
  The value of the $b$-baryon polarization can be extracted from inclusive data
at LEP with better than 10\% precision based on current statistics. We present
a new variable by which to measure the polarization, which is the ratio of the
average electron energy to the average neutrino energy. This variable is both
sensitive to polarization and insensitive to fragmentation uncertainties.


title: Transport Properties of Quark and Gluon Plasmas

abstract:
  The kinetic properties of relativistic quark-gluon and electron-photon
plasmas are described in the weak coupling limit. The troublesome Rutherford
divergence at small scattering angles is screened by Debye screening for the
longitudinal or electric part of the interactions. The transverse or magnetic
part of the interactions is effectively screened by Landau damping of the
virtual photons and gluons transferred in the QED and QCD interactions
respectively. Including screening a number of transport coefficients for QCD
and QED plasmas can be calculated to leading order in the interaction strength,
including rates of momentum and thermal relaxation, electrical conductivity,
viscosities, flavor and spin diffusion of both high temperature and degenerate
plasmas. Damping of quarks and gluons as well as color diffusion in quark-gluon
plasmas is, however, shown not to be sufficiently screened and the rates
depends on an infrared cut-off of order the ``magnetic mass", $m_{\rm mag}\sim
g^2 T$.


title: Comment on $D_s^* \to D_s \pi^0$ Decay

abstract:
  We calculate the rate for $D_s^* \rightarrow D_s \pi^0$ decay using Chiral
Perturbation Theory. This isospin violating process results from $\pi^0$ -
$\eta$ mixing, and its amplitude is proportional to $(m_d -
m_u)/\bigl(m_s-(m_u+m_d)/2 \bigr)$. Experimental information on the branching
ratio for $D_s^* \rightarrow D_s \pi^0$ can provide insight into the pattern of
$SU(3)$ violation in radiative $D^*$ decays.


title:
The off-shell electromagnetic form factors of pions and kaons in chiral
  perturbation theory

abstract:
  The off-shell electromagnetic vertex of a (pseudo-) scalar particle contains,
in general, two form factors F and G which depend, in addition to the squared
momentum transfer, on the invariant masses associated with the initial and
final legs of the vertex. Chiral perturbation theory to one loop is used to
calculate the off-shell form factors of pions and kaons. The formalism of
Gasser and Leutwyler, which was previously used to calculate the on-shell limit
of the form factor F, is extended to accommodate the most general form for
off-shell Green's functions in the pseudoscalar meson sector. We find that
chiral symmetry predicts that the form factors F of the charged pions and kaons
go off-shell in the same way, i.e., the off-shell slope at the real photon
point is given by the same new phenomenological constant $\beta_1$.
Furthermore, it is shown that at order $p^4$ the form factor F of the $K^0$
does not show any off-shell dependence. The form factors G are all related to
the form factors F in the correct fashion as required by the Ward-Takahashi
identity. Numerical results for different off-shell kinematics are presented.


title:
Form Factors in the Heavy Quark and Chiral Limit: Pole dominance in
  $\bar B\to \pi e \bar\nu_e$

abstract:
  It is shown that the form factors in the semileptonic decay of ground state
heavy mesons to light pseudoscalar mesons are dominated by the vector meson
pole at all momentum transfers. First, the general approaches to modeling form
factors in terms of quark model, pole dominance, or hybrid shapes are reviewed.
It is then shown that in the combined limits of heavy quarks, chiral symmetry,
and large~$\Nc$ the form factor is precisely pole-dominated. It is also shown
that in a two-dimensional QCD model pole-dominance occurs for any heavy quark
mass. Corrections to this limit are discussed and, to illustrate the nature of
the approximations, an explicit exact calculation of the approach to the limit
in a two-dimensional model is given.


title: Relative distributions of W's and Z's at low transverse momenta

abstract:
  Despite large uncertainties in the $W^\pm$ and $Z^0$ transverse momentum
($q_T$) distributions for $q_T\lsim 10$ GeV, the ratio of the distributions
varys little. The uncertainty in the ratio of $W$ to $Z$ $q_T$ distributions is
on the order of a few percent, independent of the details of the
nonperturbative parameterization.


title: Quark-Resonance model

abstract:
  We construct an effective Lagrangian for low energy hadronic interactions
through an infinite expansion in inverse powers of the low energy cutoff
$\Lambda_\chi$ of all possible chiral invariant non-renormalizable interactions
between quarks and mesons degrees of freedom. We restrict our analysis to the
leading terms in the $1/N_c$ expansion. The effective expansion is in
$(\mu^2/\cutoff^2 )^P \ln (\cutoff^2/\mu^2 )^Q$. Concerning the next-to-leading
order, we show that, while the pure $\mu^2/\cutoff^2 $ corrections cannot be
traced back to a finite number of non renormalizable interactions, those of
order $(\mu^2/\cutoff^2 ) \ln (\cutoff^2/\mu^2 )$ receive contributions from a
finite set of $1/\cutoff^2$ terms. Their presence modifies the behaviour of
observable quantities in the intermediate $Q^2$ region. We explicitely discuss
their relevance for the two point vector currents Green's function.


title:
A Phenomenological Study of the Process
  $e^+e^-\to\mu^+\mu^-\nu_l\bar\nu_l$ at High Energy $e^+e^-$ Colliders and
  Measurement of the $ZWW$ and $\gamma WW$ Couplings

abstract:
  We perform a detailed study of the process $e^+e^-\to
\mu^+\mu^-\nu_l\bar\nu_l$ including all contributions. The contributions other
than from real gauge boson production leads to a rich phenomenology. We explore
the use of the process as a means of precision measurement of the $ZWW$ and
$\gamma WW$ vertices. We concentrate on LEP II energies, $\sqrt{s}=200$ GeV,
and energies appropriate to the proposed Next Linear Collider (NLC) high energy
$e^+e^-$ collider with center of mass energies $\sqrt{s}=500$ and 1~TeV. At 200
GeV, the process offers, at best, a consistency check of other processes being
considered at LEP200. At 500~GeV, the parameters $\kappa_\gamma$,
$\lambda_\gamma$, $\kappa_Z$, and $\lambda_Z$ can be measured to about $\pm
0.1$ or better at 95\% C.L. while at 1 TeV, they can be measured to about $\pm
0.01$. At the high luminosities anticipated at high energy linear colliders
precision measurements are likely to be limited by systematic rather than
statistical errors.


title: Quark cluster signatures in deuteron electromagnetic interactions

abstract:
  A suggestion is made for distinguishing 2N and 6q short range correlations
within the deuteron. The suggestion depends upon observing high momentum
backward nucleons emerging from inelastic electromagnetic scattering from a
deuteron target. A simple model is worked out to see the size of effects that
may be expected.


title: Can Disordered Chiral Condensates Form? A Dynamical Perspective

abstract:
  We address the issue of whether a region of disordered chiral condensate
  (DCC), in which the chiral condensate has components along the pion
directions, can form. We consider a system going through the chiral phase
transition either via a quench, or via relaxation of the high temperature phase
to the low temperature one within a given time scale (of order $\sim 1
\rm{fm/c}$).
  We use a density matrix based formalism that takes both thermal and quantum
fluctuations into account non-perturbatively to argue that if the $O(4)$ linear
sigma model is the correct way to model the situation in QCD, then it is very
unlikely at least in the Hartree approximation, that a large ($> 10\ \rm{fm}$)
DCC region will form. Typical sizes of such regions are $\sim 1 -2 \ \rm{fm}$
and the density of pions in such regions is at most of order $\sim 0.2 /
\rm{fm}^3$. We end with some speculations on how large DCC regions may be
formed.


title: Viscosities of Quark-Gluon Plasmas

abstract:
  The quark and gluon viscosities are calculated in quark-gluon plasmas to
leading orders in the coupling constant by including screening. For weakly
interaction QCD and QED plasmas dynamical screening of transverse interactions
and Debye screening of longitudinal interactions controls the infrared
divergences. For strongly interacting plasmas other screening mechanisms taken
from lattice calculations are employed. By solving the Boltzmann equation for
quarks and gluons including screening the viscosity is calculated to leading
orders in the coupling constant. The leading logarithmic order is calculated
exactly by a full variational treatment. The next to leading orders are found
to be very important for sizable coupling constants as those relevant for the
transport properties relevant for quark-gluon plasmas created in relativistic
heavy ion collisions and the early universe.


title: QCD Phenomenology based on a Chiral Effective Lagrangian

abstract:
  We review the Nambu-Jona-Lasinio (NJL) approach to the dynamical breaking of
chiral symmetry in Quantum Chromodynamics (QCD). The subjects treated in Part I
include the vacuum structure of QCD, mass spectra and coupling constants of
hadrons, flavor mixing in mesons, the violation of the OZI rule in baryons, and
the validity of the chiral perturbation in QCD. A subtle interplay between the
axial anomaly and the current-quark masses is shown to play important roles,
and a realistic evaluation of the strangeness and heavy quark contents of
hadrons is given. In Part II, the NJL model is applied to the system at finite
temperature ($T$) and density
  ($\rho$) relevant to the early universe, interior of the neutron stars and
the ultra-relativistic heavy ion collisions. The subjects treated here include
the quark condensates in the medium, meson properties at finite $T$ ($\rho$)
and their experimental implications. A special attention is paid to fluctuation
phenomena near the critical temperature. (to be published in Physics Reports)


title: Phenomenology of models with more than two Higgs doublets

abstract:
  We study the most general Multi-Higgs-Doublet Model (MHDM) with Natural
Flavor Conservation (NFC). The couplings of a charged scalar $H_i^{\pm}$ to up
quarks, down quarks and charged leptons depend on three new complex parameters,
$X_i$, $Y_i$ and $Z_i$, respectively. We prove relations among these
parameters. We carry out a comprehensive analysis of phenomenological
constraints on the couplings of the lightest charged scalar: $X$, $Y$ and $Z$.
We find that the general MHDM may differ significantly from its minimal
version, the Two-Higgs-Doublet Model (2HDM).


title: BFKL evolution and universal structure function at very small $x$

abstract:
  The Balitskii-Fadin-Kuraev-Lipatov (BFKL) and the Gribov-Lipatov-
Dokshitzer-Altarelli-Parisi (GLDAP) evolution equations for the diffractive
deep inelastic scattering at ${1\over x} \gg 1$ are shown to have a common
solution in the weak coupling limit: $F_{2}(x,Q^{2})\propto
[\alpha_{S}(Q^{2})]^{-\gamma} \left({1\over x}\right)^{\Delta_{\Pom}}$. The
exponent $\gamma$ and the pomeron intercept $\Delta_{\Pom}$ are related by
$\gamma\Delta_{\Pom}={4\over 3}$ for the $N_{f}=3$ active flavors. The
existence of this solution implies that there is no real clash between the BFKL
and GLDAP descriptions at very small $x$. We present derivation of this
solution in the framework of our generalized BFKL equation for the dipole cross
section, discuss conditions for the onset of the universal scaling violations
and analyse the pattern of transition from the conventional
Double-Leading-Logarithm approximation for the GLDAP evolution to the BFKL
evolution at large ${1\over x}$.


title: Vortex Solutions in Two-Higgs-Doublet Systems

abstract:
  We analyze the existence of string-like defects in a two-Higgs-doublet system
having $SU(2) \times U(1)_Y \times U(1)_{Y^{\prime}}$ as gauge group. We are
able to show that, when certain relations among the parameters hold, these
configurations satisfy a set of first order differential equations (Bogomol'nyi
equations) and their energy is proportional to their topological charge.}


title: Shadowing in the Deuteron and the New $F_2^n/F_2^p$ Measurements

abstract:
  The quantity $2F_2^d(x,Q^2)/F_2^p(x,Q^2)-1$ is calculated in the region of
low $x$ and low- and moderate $Q^2$ relevant for recent NMC and E665
measurements as well as for the expected final results of the precise NMC
analysis of their low $x$ data. The calculations include nuclear shadowing
effects and a suitable extrapolation of the structure functions of free
nucleons to the low $Q^2$ region. The theoretical results are in a good
agreement with the NMC data. The shadowing correction to the experimental
estimate of the Gottfried sum is quantified.


title:
The Decay $\eta_c \rightarrow \gamma \gamma$ : A Test for Potential
  Models

abstract:
  We use a simple perturbation theory argument and measurements of charmonium
leptonic widths $\Gamma (\psi_{NS} \rightarrow e^+e^-)$ to estimate the ratio
\mbox{$R_\circ \equiv {\vert \Psi _{\eta_{c1S}}(0) \vert}^2
/{\vert\Psi_{\psi_{1 S}}(0)\vert}^2$} in the general context of non-
relativistic potential models. We obtain $R_\circ = 1.4 \pm 0.1$. We then apply
well known potential model formulas, which include lowest order QCD
corrections, to find $\Gamma (\eta_c \rightarrow \gamma \gamma )/\Gamma
(\psi_{1S} \rightarrow e^+e^-) \approx 2.2\pm 0.2$. The central value for
$\Gamma (\psi_{1S} \rightarrow e^+ e^-)$in the 1992 Particle Data Tables then
leads to a (non relativistic) prediction $\Gamma (\eta_c \rightarrow \gamma
\gamma )\approx 11.8\pm 0.8 $ keV. This prediction is in good agreement with a
recent measurement by the ARGUS collaboration, is consistent with a recent
measurement by the L3 collaboration but is significantly higher than several
earlier measurements and than previous theoretical estimates, which usually
assume $R_\circ =1$. The correction to $R_\circ =1$ is estimated to be smaller
but nonnegligible for the $b\bar b$ system. Using the current central
measurement for $\Gamma (\Upsilon_{1S}\rightarrow e^+e^-)$ we find $\Gamma
(\eta_b\rightarrow \gamma \gamma )\approx 0.58\pm 0.03$ keV. A rough estimate
of relativistic corrections reduces the expected two photon rates to about 8.8
keV and 0.52 keV for the $\eta_c$ and $\eta_b$ mesons respectively. Such
corrections


title: Photoproduction of $WH$ signal at electron-proton Colliders

abstract:
  We present the photoproduction of an intermediate mass Higgs (IMH) boson
associated with a $W$ boson at the future electron-proton colliders using
bremsstrahlung photon beam or laser backscattered photon beam. With
bremsstrahlung photon beam the search for the IMH boson is unfavorable because
of the small signal rate. But with laser photon beam the search is viable due
to a much larger rate, and provided that the $B$-identification is efficient
and $m(b\bar b)$ measurement has a good resolution.


title: Color, Spin and Flavor Diffusion in Quark-Gluon Plasmas

abstract:
  In weakly interacting quark-gluon plasmas diffusion of color is found to be
much slower than the diffusion of spin and flavor because color is easily
exchanged by the gluons in the very singular forward scattering processes. If
the infrared divergence is cut off by a magnetic mass, $m_{mag}\sim \alpha_sT$,
the color diffusion is $D_{color}\sim (\alpha_s\ln(1/\alpha_s)T)^{-1}$, a
factor $\alpha_s$ smaller than spin and flavor diffusion. A similar effect is
expected in electroweak plasmas above $M_W$ due to $W^\pm$ exchanges. The color
conductivity in quark-gluon plasmas and the electrical conductivity in
electroweak plasmas are correspondingly small in relativistic heavy ion
collisions and the very early universe.


title: Semiclassical transition probabilities for interacting oscillators

abstract:
  Semiclassical transition probabilities characterize transfer of energy
between "hard" and "soft" modes in various physical systems. We establish the
boundary problem for singular euclidean solutions used to calculate such
probabilities. Solutions are found numerically for a system of two interacting
quartic oscillators. In the double-well case, we find numerical evidence that
certain regular {\em minkowskian} trajectories have approximate stopping points
or, equivalently, are approximately periodic. This property leads to estimates
of tunneling excitation probabilities in that system and suggests that similar
estimates may be possible in other systems with tunneling.


title: Constraints From $b \to s\gamma$ on the Left-Right Symmetric Model

abstract:
  Recent results from the CLEO Collaboration on both inclusive and exclusive
radiative $B$ decays are used to constrain the parameter space of two versions
of the Left-Right Symmetric Model. In the first scenario, when the left- and
right-handed Cabibbo-Kobayashi-Maskawa mixing matrices are equal, $V_L=V_R$,
the radiative $B$ decay data is shown to lead to strong bounds on the $W_L-W_R$
mixing angle that are quite insensitive to either the top quark or $W_R$ mass.
The second scenario examined is that of Gronau and Wakaizumi wherein $b$-quark
decays proceed only via right-handed currents and $V_L$ and $V_R$ are quite
distinct. For this model, the combined constraints from Tevatron $W_R$
searches, the $B$ lifetime, and radiative $B$ decays lead to a very highly
restricted allowed range for the $W_L-W_R$ mixing angle.


title: Chiral Effects in the Confining QCD Vacuum

abstract:
  Confining configurations are introduced into the standard instanton vacuum
model. This drastically improves theoretical properties of the vacuum:
instanton size density $d(\rho)$ stabilizes at $\rho\sim 0.2 fm$, all chiral
effects are formulated in a gauge-invariant way and quarks are confined. An
interesting interplay of chiral and confining dynamics is observed; for the
realistic values of parameters the Georgi-Manohar picture emerges with chiral
radius $R_{ch}\sim \rho\sim 0.2 fm$ much less than confining radius $R_c\sim$
hadron radius $\sim 1 fm$. In the limit $R_{ch}\ll R_c$ the chiral mass
$M_{ch}(p)$ is unaffected by confinement and can be taken in the local limit
$M_{ch}(p=0)$. Different types of effective chiral Lagrangians (ECL) are
obtained, containing all or a part of gluon, quark and Nambu--Goldstone--meson
fields. The ECL are manifestly gauge--invariant and in the limit of no gluon
fields coincide with those found previously.
  The problem of the double role of the pion -- as a Goldstone meson or as a
$q\bar{q}$ system is briefly disscussed using confining ECL with quarks, mesons
and gluons.


title: QCD and Quark/Hadron Matter

abstract:
  A brief review on the recent theoretical progress in hot/dense QCD is given.
Special emphasis is put on the non-perturbative aspects of QCD plasma and the
modification of hadron proporties near the critical temperature of chiral
transition.


title: What is the statistical significance of the solar neutrino flux problem?

abstract:
  Uniform random numbers, not Gaussian random numbers, should have been used
with Standard Solar Models to estimate the effect on the neutrino flux of
uncertainties in input data. The observed discrepancy is therefore probably
quite smaller than currently accepted.


title: Non-Abelian Plane-Waves in the Quark-Gluon Plasma

abstract:
  We present new, non-abelian, solutions to the equations of motion which
describe the collective excitations of a quark-gluon plasma at high
temperature. These solutions correspond to longitudinal and transverse
plane-waves propagating through the plasma.


title: An introduction to technicolor

abstract:
  In these lectures we present the motivation for dynamical electroweak
symmetry breaking and its most popular realization, technicolor. We introduce
the basic ideas of technicolor and its companion theory of flavor, extended
technicolor. We review the classical theory of technicolor, based on naive
scaling from quantum chromodynamics, and discuss the classical theory's fatal
flaws. Finally, we describe the principal attempt to correct these flaws, the
theory of walking technicolor.


title: Experimental aspects of SU(5)xU(1) supergravity

abstract:
  We study various aspects of $SU(5)\times U(1)$ supergravity as they relate to
the experimental verification or falsification of this model. We consider two
string-inspired, universal, one-parameter, no-scale soft-supersymmetry-breaking
scenarios, driven by the $F$-terms of the moduli and dilaton fields. The model
is described in terms of the supersymmetry mass scale (\ie, the chargino mass
$m_{\chi^\pm_1}$), $\tan\beta$, and the top-quark mass. We first determine the
combined effect on the parameter space of all presently available direct and
indirect experimental constraints, including the LEP lower bounds on sparticle
and Higgs-boson masses, the $b\to s\gamma$ rate, the anomalous magnetic moment
of the muon, the high-precision electroweak parameters $\epsilon_1,\epsilon_b$
(which imply $m_t\lsim180\GeV$), and the muon fluxes in underground detectors
(neutrino telescopes). For the still-allowed points in
$(m_{\chi^\pm_1},\tan\beta)$ parameter space, we re-evaluate the experimental
situation at the Tevatron, LEPII, and HERA. In the 1994 run, the Tevatron could
probe chargino masses as high as 100 GeV. At LEPII the parameter space could be
explored with probes of different resolutions: Higgs boson searches, selectron
searches, and chargino searches. Moreover, for $m_t\lsim150\GeV$, these
Higgs-boson searches could explore all of the allowed parameter space with
$\sqrt{s}\lsim210\GeV$.


title: $I=0,1$ $\pi\pi$ and $I=1/2$ $K\pi$ Scattering using Quark Born Diagrams

abstract:
  We extend the quark Born diagram formalism for hadron-hadron scattering to
processes with valence $q\bar q$ annihilation, specifically $I=0$ and $I=1$
$\pi\pi$ and $I=1/2$ $K\pi$ elastic scattering. This involves the $s$-channel
hybrid annihilation process $q^2\bar q^2 \to q\bar q g \to q^2\bar q^2$ and
conventional $s$-channel $q\bar q$ resonances, in addition to the $t$-channel
gluon exchange treated previously using this formalism. The strength of the
$t$-channel gluon amplitude is fixed by previous studies of $I=2$ $\pi\pi$ and
$I=3/2$ $K\pi$ scattering. The $s$-channel resonances $\rho(770)$, $K^*(892)$,
$f_0(1400)$ and $K_0^*(1430)$ are incorporated as relativized Breit-Wigner
amplitudes, with masses and energy-dependent widths fitted to experimental
phase shifts. The strength of the $s$-channel gluon ``hybrid" annihilation
diagrams is problematical since the perturbative massless-gluon energy
denominator must be modified to account for the effect of confinement on the
energy of the virtual hybrid state. Our naive expectation is that near
threshold the hybrid diagrams are comparable in magnitude but opposite in sign
to the contribution predicted using massless perturbative gluons. Fitting the
strength of this amplitude to $I=0$ $\pi\pi$ and $I=1/2$ $K\pi$ S-wave data
gives a result consistent with this expectation. We find good agreement with
experimental phase shifts from threshold to 0.9 GeV in $\pi\pi$ and 1.6 GeV in
$K\pi$ using this approach. We conclude that the most important contribution to
low energy S-wave scattering in these channels arises from the nonresonant
quark Born diagrams, but that the low-energy wings of the broad $s$-channel
resonances $f_0(1400)$ and $K^*_0(1430)$ also give important contributions near
threshold. The nonresonant contributions are found to be much smaller in $L\;


title:
A Theoretical Prediction for Exclusive Decays $B \rightarrow K(K^*)
  \eta_c$

abstract:
  The decay rates for the exclusive B decays $B \rightarrow K \eta_c $ and $B
\rightarrow K^* \eta_c$ are calculated in the context of the heavy quark
effective theory. We obtain $\Gamma (B \rightarrow K \eta_c )/\Gamma
(B\rightarrow K\psi )=1.6 \pm 0.2$ and $\Gamma (B\rightarrow K^*\eta_c)/\Gamma
(B \rightarrow K^*\psi )=0.39 \pm 0.04$. These results lead to estimates $BR(B
\rightarrow K \eta_c)=(0.11 \pm 0.02) \% $ and $BR(B \rightarrow K^* \eta_c)=
(0.05 \pm 0.01) \% $ if we use the central current experimental values for
$B\rightarrow (K,K^*)\psi $ branching ratios.


title: QCD Constrains on the Shape of Polarized Quark and Gluon Distributions

abstract:
  We develop simple analytic representations of the polarized quark and gluon
distributions in the nucleon at low $Q^2$ which incorporate general constraints
obtained from the requirements of color coherence of gluon couplings at $x \sim
0$ and the helicity retention properties of perturbative QCD couplings at $x
\sim 1.$ The unpolarized predictions are similar to the $D_0'$ distributions
given by Martin, Roberts, and Stirling. The predictions for the quark helicity
distributions are compared with polarized structure functions measured by the
E142 experiment at SLAC and the SMC experiment at CERN.


title: Two-Loop Neutrino Masses and the Solar Neutrino Problem

abstract:
  The addition of $m$ singlet right-handed neutrinos to the Standard Model
leads to radiatively generated mass corrections for the $SU(2)_L $ doublet
neutrinos. For those neutrinos which are massless at the tree level after this
addition, this implies a small mass generated at the two-loop level via
$W^{\pm}$ exchange. We calculate these mass corrections exactly by obtaining an
analytic form for the general case of $n$ doublets and $m$ singlets. As a
phenomenological application, we consider the $m=1$ case and examine the masses
and mixings of the doublet neutrinos which arise as a result of the two-loop
correction in the light of experimental data from two sources which may shed
light on the question of neutrino masses. These are(a) the neutrino detectors
reporting a solar neutrino deficit (and its resolution via
Mikheyev-Smirnov-Wolfenstein matter oscillations), and
  (b) the COBE satellite data on the non-zero angular variations of the cosmic
microwave background temperature (and its possible implications for hot dark
matter). Within the framework of the extension considered here, which leaves
the gauge group structure of the Standard Model intact, we show that it is
possible for neutrinos to acquire small masses naturally, with values which are
compatible with current theoretical bias and experimental data.


title:
Gluon dipole penguin contributions to $\epsilon'/\epsilon$ and CP
  violation in Hyperon decays in the Standard Model

abstract:
  We consider the gluon dipole penguin operator contributions to
$\epsilon'/\epsilon$ and CP violation in hyperon decays. It has been proposed
by Bertolini et al. that the contribution to $\epsilon'/\epsilon$ may be
significant. We show that there is a cancellation in the leading order
contribution and this contribution is actually suppressed by a factor of order
O($m_\pi^2, m_K^2)/\Lambda^2$. We find that the same operator also contributes
to CP violation in hyperon decays where it is not suppressed. The gluon dipole
penguin operator can enhance CP violation in hyperon decays by as much as 25\%.


title: Neutron Electric Dipole Moment in Two Higgs Doublet Model

abstract:
  We study the effect of the "chromo-electric" dipole moment on the electric
dipole moment(EDM) of the neutron in the two Higgs doublet model. We
systematically investigate the Weinberg's operator $O_{3g}=GG\t G$ and the
operator $O_{qg}=\bar q\sigma\t Gq$, in the cases of $\tan\b\gg 1$, $\tan\b\ll
1$ and $\tan\b\simeq 1$. It is shown that $O_{sg}$ gives the main contribution
to the neutron EDM compared to the other operators, and also that the
contributions of $O_{ug}$ and $O_{3g}$ cancel out each other. It is pointed out
that the inclusion of second lightest neutral Higgs scalar adding to the
lightest one is of essential importance to estimate the neutron EDM. The
neutron EDM is considerably reduced due to the destructive contribution with
each other if the mass difference of the two Higgs scalars is of the order
$O(50\G)$.


title: How Can We Obtain a Large Majorana-Mass in Calabi-Yau Models ?

abstract:
  In a certain type of Calabi-Yau superstring models it is clarified that the
symmetry breaking occurs by stages at two large intermediate energy scales and
that two large intermediate scales induce large Majorana-masses of right-handed
neutrinos. Peculiar structure of the effective nonrenormalizable interactions
is crucial in the models. In this scheme Majorana-masses possibly amount to
$O(10^{9 \sim 10}\gev)$ and see-saw mechanism is at work for neutrinos. Based
on this scheme we propose a viable model which explains the smallness of masses
for three kind of neutrinos $\nu _e, \nu _{\mu} \ {\rm and}\ \nu _{\tau}$.
Special forms of the nonrenormalizable interactions can be understood as a
consequence of an appropriate discrete symmetry of the compactified manifold.


title:
BBBREM - Monte Carlo simulation of radiative Bhabha scattering in the
  very forward direction

abstract:
  A fast and simple Monte Carlo program is presented that simulates single
Bremsstrahlung in Bhabha scattering, e+e- --> e+e-gamma, without constraints on
scattering angles. This allows the study of this process at arbitrarily small,
or even vanishing, scattering angles. Experimental cuts can be imposed on an
event-by-event basis, allowing for detailed studies of the process as a
limitation to beam lifetimes, or a luminosity-measuring device, in e+e- storage
rings. As an application, we show that the easy introduction of a cutoff
parameter, corresponding to the characteristic distance between particles in
the bunches, gives a reduced cross section that is in good agreement with
observation.


title: What New Physics Can Double Beta Decay Experiments Hope to See?

abstract:
  Double-beta decay experiments have been traditionally interpreted in terms of
the Gelmini-Roncadelli triplet majoron model, which has been ruled out by LEP.
We briefly survey here the kinds of physics to which these experiments might be
sensitive in the light of the LEP constraints. We identify six broad categories
of models, including some new categories which have not been previously
considered.


title: A new formulation of the effective theory for heavy particles

abstract:
  We derive the effective theories for heavy particles with a functional
integral approach by integrating away the states with high velocity and with
high virtuality. This formulation is non-perturbative and has a close
connection with the Wilson renormalization group transformation. The fixed
point hamiltonian of our transformation coincides with the static hamiltonian
and irrelevant operators can be identified with the usual $1/M$ corrections to
the static theory. No matching condition has to be imposed between the full and
the static theory operators with our approach. The values of the matching
constants come out as a dynamical effect of the renormalization group flow.


title:
A model for $q^2\bar{q}^2$ systems illustrated by an application to
  $K\bar{K}$ scattering

abstract:
  In the paper is presented a four-body potential model for $q^2\bar{q}^2$
systems which includes both the spin and flavour degrees of freedom, extending
the formalism presented already in the spin independent situation. This allows
an application to a realistic situation, which is chosen to be $K\bar{K}$
scattering. It is seen that because of the gluonic effects in this multi-quark
system, the $K\bar{K}$ attraction resulting from the quark-exchange mechanism
gets appreciably decreased compared to that emerging through the naive two-body
potential approach.


title:
Gauge Hierarchy in ${\bf SU(3)_c \times SU(3)_L \times SU(3)_R}$ and Low
  Energy Implication

abstract:
  We explore the gauge hierarchy problem within the framework of supersymmetric
$SU(3)_c \times SU(3)_L \times SU(3)_R$ with a minimal set of higgs
supermultiplets. Imposition of a suitable discrete (alternatively $R$) symmetry
`prevents' the electroweak higgs doublets from becoming superheavy through
renormalizable couplings. A full resolution of the problem requires
consideration of the non-renormalizable couplings which play an essential role.
Other key differences from the minimal supersymmetric $SU(5)$ model include the
fact that the proton is stable and that an effective $5 + \bar{5}$
supermultiplet appears around the $TeV$ mass scale.


title:
The Values of $m_t$ and $\bar{\alpha_s}$ Derived from the
  Non-Observation of Electroweak Radiative Corrections at LEP: Global Fit

abstract:
  A set of equations representing the $W/Z$ mass ratio and various observables
of $Z$ decays in terms of $\bar\alpha \equiv\alpha (m_Z)$, $G_{\mu}$, $m_Z$,
$m_t$, $m_H$, $\bar\alpha_{s} \equiv\alpha_{s} (m_Z)$, $m_b$ and $m_\tau$ (all
other fermion masses being neglected) are compared with the latest data of the
four LEP detectors, which at the level of one standard deviation coincide with
their Born values. Our global fit gives: $m_t = 161^{+ 15 +16}_{-16 -22}
\bar\alpha_{s} = 0.119 \pm 0.006 \pm 0.002$, where the central values
correspond to $m_H = 300$ GeV, the first errors are statistical and the second
ones represent shifts of the central values corresponding to $m_H = 1000$
GeV($+$) and 60 GeV($-$). The predicted mass of the top is smaller than in the
recent fits by 4 GeV. The {\it predicted} values of $m_W/m_Z$ and the LEP
observables, based on the fitted values of $m_t$ and $\bar{\alpha}_s$, show a
weak dependence on $m_H$ and differ by several {\it predicted} standard
deviations from the corresponding Born values. The uncertainties of the
predicted values and their deviations from the corresponding Born values
determine the experimental accuracy required to observe electroweak radiative
corrections.


title:
Scaling law for the $\Upsilon(4S) \to B \bar B$ and $\psi(3770) \to D
  \bar D$ decay constants from effective sum rules

abstract:
  Sum rules for exclusive production of heavy meson pairs in $e^+e^-$
annihilation are used to evaluate the $\Upsilon(4S) \to B \bar B$ and
$\psi(3770) \to D \bar D$ decay widths. Infinitely heavy quark limit is
discussed, so that scaling law for the quarkonium-meson coupling constant is
derived. A value of the $B\bar B$ pair contribution into the leptonic constant
$f_{\Upsilon(4S)}$ is estimated.


title: Non-trivial Test of Electroweak Quantum Effects

abstract:
  Based on recent $W$-mass measurements, the electroweak theory is tested at
non-trivial quantum correction level, i.e., beyond the Born approximation with
$\alpha(M_Z)$ instead of $\alpha$. We can conclude that some non-Born type
corrections must exist at more than 92 % confidence level, and the
non-decoupling top-quark corrections are required at 97 % confidence level.


title: The Isospin Independent Spin-Orbit Force in the Extended Skyrme Model

abstract:
  By using the product ansatz as an approximation for the two-baryon system we
investigate the isoscalar nucleon-nucleon spin-orbit potential in an extended
Skyrme model including both fourth- and sixth-order terms. As it is the case
for the Skyrme model, we still obtain the wrong sign for this interaction.
Nevertheless, concerning the order of magnitude, the extended Skyrme model
provides a better agreement with phenomenological potentials, as compared to
the standard one.


title: Spin Force Dependence Of Nucleon Structure Functions

abstract:
  Deep inelastic structure functions for the nucleon are obtained in a
constituent quark model on the light cone. Parton model formulas are derived.
The negative slope of $F_{2}^{n}/F_{2}^{p} requires attraction between scalar
quark pairs. Color magnetism leads to a positive slope. 6 Figures are available
from author. Typeset in REVTEX.


title: Higgs Search by Neural Networks at LHC

abstract:
  We show that neural network classifiers can be used to discriminate Higgs
production from background at LHC for $ 150< M_H<200$ GeV. The results compare
favourably with ordinary multivariate analysis.


title: Gluon Condensates, Quark Matter Equation of State and Quark Stars

abstract:
  We consider here quark matter equation of state including strange quarks and
taking into account a nontrivial vacuum structure for QCD with gluon
condensates. The parameters of condendsate function are determined from
minimisation of the thermodynamic potential. The scale parameter of the gluon
condensates is fixed from the SVZ parameter in the context of QCD sum rules at
zero temperature and zero baryon density. The equation of state for strange
matter at zero temperature as derived is used to study quark star structure
using Tolman Oppenheimer Volkoff equations. Stable solutions for quark stars
are obtained with a large Chandrasekhar limit as 3.2 $M_\odot$ and radii around
17 kms.


title: Magnetic Moment of the $\Lambda_c$, $\Xi_{c1}^+$ and $\Xi_{c1}^0$

abstract:
  The magnetic moment of the $\Lambda_c$, $\Xi_{c1}^+$ and $\Xi_{c1}^0$ vanish
when the charm quark mass is taken to infinity because the light degrees of
freedom are in a spin zero configuration. The heavy quark spin-symmetry
violating contribution from the light degrees of freedom starts at order
$1/m_c$, the same order as the contribution from the heavy charm quark. We
compute the leading long-distance contribution to the magnetic moments from the
spin-symmetry breaking $\Sigma_c^*-\Sigma_c $ mass splitting in chiral
perturbation theory. These are nonanalytic in the pion mass and arise from
calculable one-loop graphs. Further, the difference between the magnetic
moments of the charged charmed baryons is independent of the charm quark mass
and of the subleading local counterterm.


title: Strongly Interacting Longitudinal Gauge Bosons In Supersymmetric Models

abstract:
  A non-linear sigma model effective lagrangian is analyzed for theories in
which supersymmetry is softly broken at scales below the electroweak symmetry
breaking scale. Besides the gauge and matter supermultiplets, the low energy
theory contains only three Goldstone chiral multiplets. The higgsino, gaugino
as well as the charged and neutral Higgs bosons have (light) phenomenologically
acceptable masses, the values of which depend on the explicit soft
supersymmetry breaking parameters. In addition, the longitudinal vector bosons
become strongly interacting at high energies ($M_Z \ll E \ll 4\pi v$). The
equivalence theorem is exploited in order to obtain their scattering
amplitudes. Furthermore, supersymmetry results in enhanced longitudinal vector
boson production of Higgs bosons.


title:
Influence of Kaonic Resonances on the CP Violation in $B\to
  K^*\gamma$Like Processes

abstract:
  We consider CP violating effects in decays of the type $B\rightarrow
k_i\gamma \rightarrow K\pi\gamma$, $K^*\pi\gamma$ and $K\rho\gamma$, where
$k_i$ represents a strange meson resonance. We include in our calculations five
of the low-lying resonances with quantum numbers ($J^P$) $1^-$, $1^+$ and
$2^+$. At the quark level these decays are driven by the penguin graph as well
as tree graphs. CP violation arises due to the difference in the CKM phase
between these graphs. We model the final state interaction of the hadronic
system using the low lying $k_i$ resonances. We find that radiative decays of B
mesons give rise to four of the five kaonic resonances at about $1$ to $7 \%$
of the inclusive $b \rightarrow s \gamma$ rate. We find that the probability of
formation of the other three higher resonances is roughly the same as that of
$K^*(892)$, which was recently seen at CLEO. In addition to the partial rate
asymmetry which arises due to interference between resonances of the same
quantum numbers, we show how interference between resonances of the same
parity, and also between resonances of the opposite parity, result in two
different types of energy asymmetries. CP differential asymmetries at the level
of a few percent seem possible. We thus obtain CP violating distributions which
may be observed in a sample of about $10^9$\relax $B^\pm$ mesons.


title: Production of four heavy quarks and $B_c$-mesons at the $Z^0$-boson pole

abstract:
  The cross-section for the production of $b{\bar b} c{\bar c}$ quarks in
$e^+e^-$ annihilation, that proves to be at a level of $\sigma (e^+e^-
\rightarrow b{\bar b} c{\bar c})/
  \sigma (e^+e^- \rightarrow b{\bar b}) \sim 10^{-2}$ for ${\sqrt s}=M_Z$ is
calculated within the frames of the QCD perturbation theory. The cross sections
for the associated production of $1S$- and $2S$-wave states of $B_c$-meson in
the reaction $e^+e^- \rightarrow B_c b{\bar c}$ were calculated in the
nonrelativistic model of a heavy quarkonium. The fragmentation function of
$b\to B_c^{(*)}$ is analysed in the scaling limit. The number of
$\Lambda_{bc}$-hyperons to be expected at LEP is estimated on the basis of the
assumption on quark-hadron duality.


title: Equivalence of Dimensional Reduction and Dimensional Regularisation

abstract:
  For some years there has been uncertainty over whether regularisation by
dimensional reduction (DRED) is viable for non-supersymmetric theories. We
resolve this issue by showing that DRED is entirely equivalent to standard
dimensional regularisation (DREG), to all orders in perturbation theory and for
a general renormalisable theory. The two regularisation schemes are related by
an analytic redefinition of the couplings, under which the $\b$-functions
calculated using DRED transform into those computed in DREG. The $S$-matrix
calculated using DRED is numerically equal to the DREG version, ensuring that
both schemes give the same physics.


title: $K^+\to\pi^+\nu\bar\nu$ Beyond Leading Logs and $V_{td}$

abstract:
  The calculation of QCD corrections beyond the leading logarithmic
approximation for the short-distance dominated rare decay
$K^+\to\pi^+\nu\bar\nu$ is summarized. This analysis requires the complete
${\cal O}(\alpha_s)$ corrections to the top contribution to all orders in the
top-quark mass and a two-loop renormalization group (RG) calculation for the
charm contribution. The inclusion of these QCD corrections reduces considerably
the theoretical uncertainty in calculating $B(K^+\to\pi^+\nu\bar\nu)$.
Implications for the determination of $V_{td}$ from this decay are discussed.


title: Constraints and Transport in Electroweak Baryogenesis

abstract:
  In unconstrained thermal equilibrium a local potential for total or fermionic
hypercharge does not bias electroweak anomalous processes. We consider two
proposed mechanisms for electroweak baryogenesis in this light. In
`spontaneous' baryogenesis, which was argued to apply in the `adiabatic' limit
of thick, slow walls, a non-zero result was obtained by setting globally
conserved charges to be zero {\it locally}. We show that this is a poor
approximation unless the walls are very thick. For more realistic wall
thicknesses the local equilibrium approached as the wall velocity
$v_w\rightarrow 0$ has zero baryon number violation and nonzero global charges
on the wall. In the `charge transport' mechanism, argued to apply to the case
of thin fast walls, calculations of the magnitude of the asymmetry also involve
the same error. In corrected calculations the local values of global charges
should be determined dynamically rather than fixed locally to zero.


title: Efficient Electroweak Baryogenesis from Lepton Transport

abstract:
  One mechanism for generating a baryon asymmetry at the electroweak phase
transition involves propagation of particle asymmetries generated by reflection
from the bubble walls into the unbroken phase. Hitherto attention has focussed
on top quarks because of their large mass and thus effective scattering from
bubble walls. In this paper we point out that leptons may be more efficient
mediators of this type of electroweak baryogenesis, particularly for thicker
bubble walls favored by perturbative calculations. We carry out an analytic
calculation of each stage of the mechanism and conclude it produces a baryon
asymmetry compatible with observations for a wide range of parameters.


title: Sea Contributions and Nucleon Structure

abstract:
  We suggest a general formalism to treat a baryon as a composite system of
three quarks and a `sea'. In this formalism, the sea is a cluster which can
consists of gluons and quark-antiquark pairs. The hadron wave function with a
sea component is given. The magnetic moments, related sum rules and axial weak
coupling constants are obtained. The data seems to favor a vector sea rather
than a scalar sea. The quark spin distributions in the nucleon are also
discussed.


title: The Role of $\gamma_5$ in Dimensional Regularization

abstract:
  We discuss the consistency of a new \gf -scheme with renormalization. In
particular we study the power-counting behaviour of multiloop graphs to prove
its consistency. As a side effect we obtain a short proof of the Adler-Bardeen
theorem. Further we show that this \gf-scheme does not modify the BRST
identities at any loop orders in contrast to BM type schemes.


title: Topics in Chiral Perturbation Theory

abstract:
  I consider some selected topics in chiral perturbation theory (CHPT). For the
meson sector, emphasis is put on processes involving pions in the isospin zero
S-wave which require multi-loop calculations. The advantages and shortcomings
of heavy baryon CHPT are discussed. Some recent results on the structure of the
baryons are also presented.


title: Model Calculation of Nucleon Structure Functions

abstract:
  Deep inelastic polarized and unpolarized structure functions for a free
nucleon are obtained in a modified Center-of-Mass bag model, which includes the
symmetry breaking effects from spin-dependent interactions. The quark
distribution functions, calculated at $Q_0^2\simeq$ (0.9GeV/c)$^2$, are evolved
to higher $Q^2$ region and compared with the data and other models. The model
gives a reasonable description for the valence part of the structure functions
at $x>0.3$. For small-$x$ region, the contributions from the sea are necessary.
The spin-dependent effects are important in describing the existing data.


title: On normalization of QCD effects in $O(m_t^2)$ electroweak corrections

abstract:
  We point out that, contrary to some recent claims, there is no intrinsic
long-distance uncertainty in perturbative calculation of the QCD effects in the
$t \tb$ and $t \bb$ loops giving the electroweak corrections proportional to
$m_t^2$. If these corrections are expressed in terms of the ``on-shell" mass
$m_t$, the only ambiguity arising is that associated with the definition of the
``on-shell" mass of a quark. The latter is entirely eliminated if the result is
expressed in terms of $m_t$ defined at short distances. Applying the
Brodsky-Lepage-Mackenzie criterion for determining the natural scale for
normalization of $\as$, we find that using the ``on-shell" mass makes this
scale numerically small in units of $m_t$. Specifically, we find that by this
criterion the first QCD correction to the $O(m_t^2)$ terms is determined by
$\as^\msb(0.15 m_t)$. Naturally, a full calculation of three-loop graphs is
needed to completely quantify the scale.


title: Relating the pion decay constant to the chiral restoration temperature

abstract:
  We review the relationship between the pion decay constant $f_\pi$, the
chiral symmetry restoration temperature $T_c$ and the phenomenology of low
energy chiral symmetry breaking in view of the recent confirmation of the
existence of a sigma meson with a mass of 600-700 MeV.


title: Dark Matter and Solar Neutrinos in SUSY

abstract:
  In the Supersymmetric extension of the Standard Model with minimal particle
content the three neutrinos can have non trivial masses and mixings, generated
at 1 loop due to renormalizable lepton number violating interactions. We show
that the resulting mass matrix can provide simultaneously a significant amount
of the Dark Matter of the Universe and solve the solar neutrino problem, if the
free parameters of the model are fixed to values which are consistent with all
the present accelerator and cosmological constraints. The theory also predicts
new effects in future experiments looking for neutrino oscillations.


title:
Radiative Decay of Vector Quarkonium: Constraints on Glueballs and Light
  Gluinos

abstract:
  Given a resonance of known mass, width, and J^{PC}, we can determine its
gluonic branching fraction, b(R->gg), from data on its production in radiative
vector quarkonium decay, V -> gamma+R. For most resonances b(R->gg) is found to
be O(10%), consistent with being q-qbar states, but we find that both
pseudoscalars observed in the 1440 MeV region have b(R->gg) ~ 1/2 - 1, and
b(f_0^{++}->gg) ~ 1/2. As data improves, b(R->gg) should be a useful
discriminator between q-qbar and gluonic states and may permit quantitative
determination of the extent to which a particular resonance is a mixture of
glueball and q-qbar. We also examine the regime of validity of pQCD for
predicting the rate of V -> gamma+eta_gluino, the ``extra'' pseudoscalar bound
state which would exist if there were light gluinos. From the CUSB limit on
peaks in Upsilon -> gamma X, the mass range 3 GeV < m(eta_gluino) < 7 GeV can
be excluded. An experiment must be significantly more sensitive to exclude an
eta_gluino lighter than this.


title: Fermion Scattering off CP-Violating Electroweak Bubble Wall

abstract:
  A general prescription to solve the Dirac equation in the presence of
CP-violating electroweak bubble wall is presented. The profile of the bubble
wall is not specified except that the wall height is $m_0$ and zero deep in the
broken- and the symmetric-phase regions, respectively, where $m_0$ is a fermion
mass given by the Higgs-vacuum-expectation value and the Yukawa coupling. The
CP-violating effects are evaluated by regarding CP-violating part of the bubble
wall as a perturbation to CP-conserving solutions. The basic quantity,
$R_{R\rightarrow L}-\bar R_{R\rightarrow L}$, which would contribute to the
cosmological baryon asymmetry, is estimated for some typical profiles of the
wall, where $R_{R\rightarrow L}$($\bar R_{R\rightarrow L}$) is the reflection
coefficient of right-handed chiral fermion (anti-fermion).


title: Heavy Baryons as Skyrmion with $1/m_Q$ Corrections

abstract:
  We take into account the $1/m_Q$ corrections upto $1/N_c$ order in the
heavy-meson-soliton bound state approach for heavy baryons. With these
corrections, the mass spectra of baryons with $c$-quark as well as of those
with $b$-quark are well reproduced. For charmed baryons, however, the
correction to the mass spectra amounts to about 300 MeV, which is not small
compared to the leading order binding energy, $\sim 800$ MeV.


title: Low-energy sum rules and large-$N_c$ consistency conditions

abstract:
  The large-$N_c$ consistency conditions for axial vector and isovector
magnetic couplings of pions to baryons are discussed from the point of view of
low-energy current-algebra sum rules (Adler-Weisberger, Cabibbo-Radicati). In
particular, we show how the result that ratios of axial vector and isovector
magnetic coupling constants get corrections only at the order $1/N_c^2$ follows
from the $N_c$-counting of appropriate cross sections. This counting is
performed using various approaches at the quark and hadronic level. Other
implications of our method are also presented.


title: A New Perspective on Electroweak Strings

abstract:
  The vortex solution (Z-string) of the electroweak interactions can be
interpreted as the 2-dimensional sphaleron at the top of a non-contractible
sphere. The same holds for another type of solution, the W-string.


title: Single-$W$ versus $W$-pair production at LEP~II

abstract:
  This paper is a study of the single-$W$ and $W$-pair production at LEP~II. I
show that the sensitivity of the single-$W$ production channel on the anomalous
trilinear couplings of $W$ is essentially the same as the sensitivity of the
channel $e^+e^-\to W^+W^-$. Therefore, even without the reconstruction of the
$W$ boson, deviations form the SM predictions on trilinear couplings can be
measured at the level of $0.2 - 1$, using single-$W$ production at LEP~II.


title: Deep inelastic scattering at HERA and the BFKL pomeron

abstract:
  We present a BFKL phenomenology of structure functions in the framework of
the generalized BFKL equation for the dipole cross section proposed by us
recently. We show that the HERA measurements of excitation of charm at $Q^{2}
\lsim $10 GeV$^{2}$ allow determination of the intercept of the BFKL pomeron. A
comparison with the experimental data suggests a large contribution from the
nonperturbative cross section for colour dipoles of large size $r$.


title: Mesons with Beauty and Charm: Spectroscopy

abstract:
  Applying knowledge of the interaction between heavy quarks derived from the
study of $c\overline{c}$ and $b\overline{b}$ bound states, we calculate the
spectrum of $c\overline{b}$ mesons. We compute transition rates for the
electromagnetic and hadronic cascades that lead from excited states to the
$^1\text{S}_0$ ground state, and briefly consider the prospects for
experimental observation of the spectrum.


title: Supersymmetric Dark Matter: Relic Density and Detection

abstract:
  The Lightest Supersymmetric Particle (LSP) makes a good Dark Matter (DM)
candidate, since its relic density quite naturally comes out close to the
cosmologically required value. This is true even in minimal Supergravity models
with radiative symmetry breaking, which have a rather small number of free
parameters. On the other hand, the experimental detection of SUSY DM might be
quite difficult, necessitating km$^2$ size neutrino detectors or direct
detection experiments with several tons of detector material.


title: A Precise Determination of $\tan\beta$ from Heavy Charged Higgs Decay

abstract:
  We compute the energy spectrum of charged leptons in the decay $H^+\to \bar
b+(t\to bl\nu_l)$. The shape of the lepton spectrum obtained, and also the mean
lepton energy, are sensitive to the handedness of the intermediate top quark.
This sensitivity can be used to precisely determine $\tan\beta$, a fundamental
parameter of two Higgs doublet models.


title:
Effect of Wavefunction Renormalisation in N-Flavour Qed3 at Finite
  Temperature

abstract:
  A recent study of dynamical chiral symmetry breaking in N-flavour QED$_3$ at
finite temperature is extended to include the effect of fermion wavefunction
renormalisation in the Schwinger-Dyson equations. The simple ``zero-frequency''
truncation previously used is found to lead to unphysical results, especially
as $T \to 0$. A modified set of equations is proposed, whose solutions behave
in a way which is qualitatively similar to the $T=0$ solutions of Pennington et
al. [5-8] who have made extensive studies of the effect of wavefunction
renormalisation in this context, and who concluded that there was no critical
$N_c$ (at T=0) above which chiral symmetry was restored. In contrast, we find
that our modified equations predict a critical $N_c$ at $T \not= 0$, and an
$N-T$ phase diagram very similar to the earlier study neglecting wavefunction
renormalisation. The reason for the difference is traced to the different
infrared behaviour of the vacuum polarisation at $T=0$ and at $T \not= 0$.


title:
Wavefunction-Independent Relations between the Nucleon Axial-Coupling
  g_A and the Nucleon Magnetic Moments

abstract:
  We calculate the proton's magnetic moment $\mu_p$ and its axial-vector
coupling $g_A$ as a function of its Dirac radius $R_1$ using a relativisitic
three-quark model formulated on the light-cone. The relationship between
$\mu_p$ and $g_A$ is found to be independent of the assumed form of the
light-cone wavefunction. At the physical radius $R_1=0.76$ fm, one obtains the
experimental values for both $\mu_p$ and $g_A$, and the helicity carried by the
valence $u$ and $d$ quarks are each reduced by a factor $\simeq 0.75$ relative
to their non-relativistic values. At large proton radius, $\mu_p$ and $g_A$ are
given by the usual non-relativistic formulae. At small radius, $\mu_p$ becomes
equal to the Dirac moment, as demanded by the Drell-Hearn-Gerasimov sum rule.
In addition, as $R_1 \to 0,$ the constituent quark helicities become completely
disoriented and $g_A \to 0$.


title:
High Energy Gamma--Radiation from the Galactic Center due to Neutralino
  Annihilation

abstract:
  We study the NGS (Non--dissipative Gravitational Singularity) model, which
successfully describes the non--linear stage of evolution of perturbations (see
[1], [2] and references therein). This model predicts DM density distribution
$\rho(r) \sim r^{-\alpha}$ with $\alpha \simeq 1.8$ which holds from very small
distances $r_{\rm min} \simeq 0.01~{\rm pc}$ up to very large distances $r_{\rm
max} \simeq 5~{\rm Mpc}$. Assuming the neutralino to be a CDM particle, we
calculate the annihilation of neutralinos in the vicinity of the singularity
(Galactic Center). If neutralinos are the dominant component of DM in our
Galaxy, the produced energy is enough to provide the whole observed activity of
the GC. Neutralinos of the most general composition and of mass in the range
$20~{\rm GeV} \leq m_\c \leq 1~{\rm TeV}$ are considered. We find the
neutralino compositions which give the relic density needed for the Mixed Dark
Matter (MDM) model and we evaluate for these compositions the high--energy
($E_{\gamma} > 100 ~{\rm MeV}$) gamma--ray flux under the constraint that the
radio flux is lower than the observational limit. The compositions with the
detectable gamma--ray flux which we found are provided by a set of almost pure
gaugino states with the neutralino mass between $100$ and $500$ GeV. We
demonstrate that a detectable high--energy gamma--ray flux is produced by the
neutralino annihilation also in the case when neutralinos provide a small
fraction (down to $0.1 \%$) of the DM in our Galaxy. The predicted flux is
$F_\gamma \sim 10^{-7}-10^{-8}~{\rm cm}^{-2}~{\rm s}^{-1}$ for $E_\gamma \gsim
300~{\rm MeV}$


title: $K^0 $ Decays into Three Photons

abstract:
  The decays $K_{L,S} \to 3 \gamma $ are not forbidden by any selection rules
or symmetry principles. However, gauge invariance and Bose statistics dictate
that every photon pair in these transitions has at least two units of angular
momentum. This gives rise to an extraordinary suppression. Using a simple
model, we obtain the branching ratios $B(K_L \to 3 \gamma) \sim 3 \cdot
10^{-19}$, $B(K_S \to 3 \gamma) \sim 5 \cdot 10^{-22} $.


title: R Parity in Standard--like Superstring Models

abstract:
  We investigate the R symmetries of standard--like superstring models. At the
level of the cubic superpotential there are three global $U(1)$ R symmetries.
These are broken explicitly by $N>3$ terms in the superpotential and
spontaneously by scalar VEVs necessary to preserve supersymmetry at $M_P$. A
$Z_2$ discrete symmetry remains but is equivalent to fermion number modulo 2.
These models possess an effective R parity which arises from the interplay
between the gauged $U(1)_{B-L}$ and $U(1)_{r_{j+3}}$.


title: Stability of an electroweak string with a fermion condensate

abstract:
  A solution of the standard electroweak theory with a single lepton family is
constructed, consisting of a cosmic string and a fermion condensate within its
core. The stability of this system to small perturbations is examined, and it
is found that stability is not enhanced relative to the bare electroweak
string. The presence of quark zero modes is shown to violate the existence
criteria for embedded defects.


title:
Slepton pair production in e+e- collision in supersymmetric left-right
  model

abstract:
  The pair production of sleptons in electron-positron collisions is
investigated in a supersymmetric left-right model. The cross section is found
considerably larger than in the minimal supersymmetric version of the Standard
Model (MSSM) because of more contributing graphs. A novel process is a doubly
charged higgsino exchange in u-channel, which makes the angular distribution of
the final state particles and the final state asymmetries to differ from those
of the MSSM. It also allows for the flavour non-diagonal final states $\tilde
e\tilde\mu$, $\tilde e\tilde\tau$ and $\tilde \mu\tilde\tau$, forbidden in the
MSSM. These processes also give indirect information about neutrino mixings
since they depend on the same couplings as the Majorana mass terms of the
right-handed neutrinos.


title:
First estimates of the $(\alpha + \beta)^{\pi}$ from two--photon
  experiments

abstract:
  We carry out the semi--model analysis of existing data on the angular
distributions of the $\gamma\gamma\rightarrow\pi^+ \pi^- ,\ \pi^0 \pi^0$
reactions with purpose to obtain S-wave cross section and D-wave's parameters.
In the first time we obtain from experiment the sum of electrical and magnetic
pion polarizabilities: $(\alpha + \beta)^{\pi^+} = 0.28 \pm 0.07$ (MARK-II
\cite{M2}), \ \ $(\alpha + \beta)^{\pi^+} = 0.38 \pm 0.05$ (CELLO
\cite{CELLO}), \ \ $(\alpha + \beta)^{\pi^0} = 1.26 \pm 0.06$ (Crystal Ball
\cite{CB}) \ \ in units of $10^{-42} \ cm^3$ ($e^2=4 \pi \alpha$).


title: Evolution Equations for the Quark-Meson Transition

abstract:
  Evolution equations describe the effect of consecutively integrating out all
quantum fluctuations with momenta larger than some infrared cutoff scale k. We
develop a formalism for the introduction of collective degrees of freedom at
some intermediate scale and derive the corresponding evolution equations. This
allows to account for the appearance of bound states at some characteristic
length scale as, for example, the mesons in QCD. The vacuum properties,
including condensates of composite operators, can be directly infered from the
effective action for k->0. We compute in a simple QCD-motivated model with
four-quark interactions the chiral condensate \bar\psi\psi and the effective
action for pions including f_\pi. A full treatment of QCD along these lines
seems feasible but still requires substantial work. (5 figures available by
ordinary mail upon request)


title: QED at Finite Temperature in the Coulomb Gauge

abstract:
  We argue that calculations in QED at finite temperature are more conveniently
carried out in the Coulomb gauge, in which only the physical photon degrees of
freedom play a rol and are thermalized. We derive the photon propagator in this
gauge for real-time finite temperature calculations and show that the
four-fermion static Coulomb interaction that appears in the Lagrangian can be
accounted for by suitably modifying the photon propagator. The Feynman rules of
the theory are written in a manifestly covariant form, although they depend on
the velocity 4-vector $u_\mu$ of the background medium. As a first step in
showing the consistency and usefulness of this approach, we consider the
one-loop calculation of the electron self-energy $\Sigma$. It is explicitly
shown that the divergences that arise from the vacuum contribution to $\Sigma$
are independent of $u_\mu$, which implies that the counter terms that must be
included in the Lagrangian are the same as those in the vacuum.


title: New results for two-loop off-shell three-point diagrams

abstract:
  A number of exact results for two-loop three-point diagrams with massless
internal particles and arbitrary (off-shell) external momenta are presented.
Divergent contributions are calculated in the framework of dimensional
regularization.


title: Limits on Neutrino Mixing with new Heavy Particles

abstract:
  We study the effects induced by new neutral fermions below their mass
threshold, due to their possible mixing with the standard neutrinos. We use as
experimental constraints the recent results on lepton universality, together
with the measurement of the $\mu$ decay rate and the updated LEP data. In
particular, the inclusion in our data set of the most recent determinations of
the $\tau$ branching fractions, mass and lifetime implies that a previous
indication of a non-vanishing mixing for $\nu_\tau$ is no longer present. We
obtain new stringent limits on the mixing parameters between $\nu_e$,
$\nu_\mu$, $\nu_\tau$ and heavy neutral states of different weak isospin. If no
assumption on the type of neutrinos involved in the mixing is made, we find
$\snue^2<0.0071$, $\snumu^2<0.0014$ and $\snutau^2<0.033$.


title: Heavy Quark Distribution Function in QCD and the AC$^2$M$^2$ Model

abstract:
  We show that the phenomenological \ACM ansatz is consistent with QCD through
order $1/m_b$ in the description of $B\ra l\bar \nu_l+X_u$ and $B\ra \gamma
+X_s$ transitions, including their energy spectra and differential
distributions. This suggests a concrete realization for the QCD distribution
function, which we call the ``Roman'' function. On the other hand the \ACM
model description of the end-point domain in $B\ra l\bar \nu_l + X_c$ is
incompatible with QCD: a different distribution function enters the description
of $b\ra c$ decays as compared to the transitions to the massless quarks. Both
observations -- the validity of the {\ACM}-like description for heavy-to-light
transitions and the emergence of the new distribution function in the $b\ra c$
case -- are in contradiction to a recent claim in the literature. The intrinsic
limitation of the \ACM model could reveal itself in different values of the
effective $b$ quark mass from fits of the $\Lambda _b$ and $B$ decays.


title: The top-quark mass in SU(5)xU(1) supergravity

abstract:
  We show that the currently experimentally preferred values of the top-quark
mass (\ie, $130\lsim m_t\lsim180\GeV$) are naturally understood in the context
of string models, where the top-quark Yukawa coupling at the string scale is
generically given by $\lambda_t={\cal O}(g)$, with $g$ the unified gauge
coupling. A detailed study of the Yukawa sector of $SU(5)\times U(1)$
supergravity shows that the ratio of the bottom-quark to tau-lepton Yukawa
couplings at the string scale is required to be in the range
$0.7\lsim\lambda_b/\lambda_\tau\lsim1$, depending on the values of $m_t$ and
$m_b$. This result is consistent with $SU(5)\times U(1)$ symmetry, which does
{\em not} require the equality of these Yukawa couplings in the unbroken
symmetry phase of the theory. As a means of possibly predicting the value of
$m_t$, we propose a procedure whereby the size of the allowed parameter space
is determined as a function of $m_t$, since all sparticle and Higgs-boson
masses and couplings depend non-trivially on $m_t$. At present, no significant
preference for particular values of $m_t$ in $SU(5)\times U(1)$ supergravity is
observed, except that high-precision LEP data requires $m_t\lsim180\GeV$.


title:
CP Violation and Strong Phases from Penguins in $\bf B^{\pm}\rightarrow
  VV$ Decays

abstract:
  We calculate direct CP-violating observables in charged $B\to VV$ decays
arising from the interference of amplitudes with different strong and CKM
phases. The perturbative strong phases develop at order $\alpha_s$ from
absorptive parts of one-loop matrix elements of the next-to-leading logarithm
corrected effective Hamiltonian. CPT constraints are maintained. Based on this
model, we find that partial rate asymmetries between charge conjugate $B^{\pm}$
decays can be as high as 15-30\% for certain channels with branching ratios in
the $10^{-6}$ range. The small values of the coefficients of angular
correlations, which we calculated previously to be of order $10^{-2}$, are not
significantly degraded by the strong phases. The charge asymmetries of rates
and angular distributions would provide unambiguous evidence for direct CP
violation.


title:
Hadron Electromagnetic Structure: Shedding Light on Models and their
  Mechanisms

abstract:
  Strange quark contributions to the proton magnetic moment are estimated from
a consideration of baryon magnetic moment sum rules. The environment
sensitivity of quark contributions to baryon moments is emphasized. Pion cloud
contributions to proton charge radii are examined in the framework of Chiral
Perturbation Theory. The absence of scalar-diquark clustering in the nucleon is
discussed.


title: Naturally Degenerate Neutrinos

abstract:
  The solar neutrino problem, atmospheric neutrino problem, and the existence
of hot dark matter can all be economically accounted for using only the three
known neutrinos if these neutrinos all have nearly degenerate masses of a few
eV. We show how to generate this pattern of neutrino masses in a natural way
within a `see-saw' framework.


title: $\tau$ Decay and the QCD infrared fixed point

abstract:
  We apply the optimization procedure based on the Principle of Minimal
Sensitivity to the third-order calculation of $R_{\tau}$. Since the effective
couplant remains finite, freezing to a value $\alpha_s/\pi = 0.26$ at low
energies, we can actually evaluate the defining integral of $R_{\tau}$ and
compare the optimized perturbation theory result to that of the optimized
result obtained after the integral has been evaluated using contour techniques.
The good agreement shows that the optimization procedure is consistent and
suggests that the infrared fixed point is meaningful.


title:
Accomodating Solar and Atmospheric Neutrino Deficits, Hot Dark Matter,
  and a Double Beta Decay Signal

abstract:
  Neutrino mass explanations of the solar and atmospheric neutrino deficits and
a hot dark matter component require one of three patterns of those masses, as
already pointed out by us. Recently there have been indications of a
non-vanishing amplitude for neutrinoless double beta decay. If this additional
hint of neutrino mass is true, it would make even less likely the one unfavored
pattern (a sterile neutrino giving warm, rather than hot dark matter), would
alter another by making the $\nu_e$ a contributor to the hot dark matter, and
would make the third ($\nu_e$, $\nu_\mu$, and $\nu_\tau$ approximately
degenerate) much more likely than previously. For this third case we construct
a gauge model consistent with other weak interaction data. This model utilizes
a more general version of the see-saw mechanism, which is very likely to be the
source of neutrino mass, if this degenerate pattern is correct. A new supernova
constraint is utilized, and implications and tests of the different mass
matrices are noted.


title: New Trends in Particle Theory

abstract:
  I discuss some new trends in particle theory beyond the standard model. Some
topics briefly covered include elecroweak baryogenesis, gauge versus non-gauge
discrete symmetries, the strong CP problem, dynamical symmetry breaking
scenarios, supersymmetric grand unification, new aspects in low energy
supersymmetry and superstring phenomenology.


title:
Corrections to Bino Annihilation II: One-Loop Contribution to
  $\widetilde B \widetilde B \to Z^*$

abstract:
  We calculate the one-loop contribution to the bino annihilation rate due to
the process $\widetilde B \widetilde B \to Z^*$, which vanishes at tree level.


title: Lepton-antilepton Annihilation in the Massless Schwinger Model

abstract:
  We evaluate the next-to-leading order radiative corrections to a process in
the massless Schwinger model that is the analogue of the $e^+e^-$ inclusive
annihilation into hadrons process in QCD. We then carry out an asymptotic
expansion of the calculable exact result and find that it agrees with the
perturbative answer. However, we also find that higher orders in the asymptotic
expansion involve terms that depend on the logarithm of the strong coupling
constant.


title: Dynamical CP Violation in Composite Higgs Models - a Review -

abstract:
  In composite Higgs models it was pointed out that there is a possibility to
violate CP symmetry dynamically. We demonstrated a simple model of dynamical CP
violation in composite Higgs models. We calculated the neutron electric dipole
moment in our model and the constraint for our model is discussed. (Talk
presented at the Third KEK Topical Conference on CP Violation, 16-18 November,
1993. The main part of this talk is based on the work in collaboration with S.
Hashimoto and T. Muta.)


title: Heavy--light mesons in a bilocal effective theory

abstract:
  Heavy--light mesons are described in an effective quark theory with a
two--body vector--type interaction. The bilocal interaction is taken to be
instantaneous in the rest frame of the bound state, but formulated covariantly
through the use of a boost vector. The chiral symmetry of the light flavor is
broken spontaneously at mean field level. The framework for our discussion of
bound states is the effective bilocal meson action obtained by bosonization of
the quark theory. Mesons are described by 3--dimensional wave functions
satisfying Salpeter equations, which exhibit both Goldstone solutions in the
chiral limit and heavy--quark symmetry for $m_Q\rightarrow\infty$. We present
numerical solutions for pseudoscalar $D$-- and $B$--mesons. Heavy--light meson
spectra and decay constants are seen to be sensitive to the description of
chiral symmetry breaking (dynamically generated vs.\ constant quark mass).


title: Electromagnetic Contributions to the Schiff Moment

abstract:
  The Schiff moment, $\smij$, is a parity and time reversal violating
fermion-fermion coupling. The nucleus-electron Schiff moment generically gives
the most important contribution to the electric dipole moments of atoms and
molecules with zero net intrinsic electronic spin and nuclear spin ${1 \over
2}$. Here, the electromagnetic contribution to the Schiff moment, $\emij$, is
considered. For a nucleon, the leading chirally violating contribution to this
interaction is calculable in the chiral limit in terms of the parity and time
reversal violating pion-nucleon coupling. For the Schiff moment of heavy
nuclei, this chiral contribution is somewhat smaller than the finite size
effect discussed previously in the literature.


title: Mass Bounds in the Standard Model

abstract:
  Nonperturbative triviality and vacuum stability mass bounds are obtained for
the Higgs scalar and top quark degrees of freedom in the standard electroweak
model using Wilson renormalization group techniques. Particular attention is
given to the effect of the generalized top Yukawa coupling on the scalar mass
upper bound.


title: Explicit Electroweak symmetry breaking?

abstract:
  We hypothesise that all electroweak symmetry breaking terms such as fermion
masses and the W and Z gauge boson masses arise radiatively from just one
explicit symmetry breaking term in the Lagrangian. Our hypothesis is motivated
by the lack of experimental support and the lack of predictivity of the
standard symmetry breaking scenario. We construct a simple model which
illustrates our ideas. We also discuss the possible importance of scale
invariance.


title: Electric charge quantization without anomalies?

abstract:
  In gauge theories like the standard model, the electric charges of the
fermions can be heavily constrained from the classical structure of the theory
and from the cancellation of anomalies. We argue that the anomaly conditions
are not quite as well motivated as the classical constraints, since it is
possible that new fermions could exist which cancel potential anomalies. For
this reason we examine the classically allowed electric charges of the known
fermions and we point out that the electric charge of the tau neutrino is
classically allowed to be non-zero. The experimental bound on the electric
charge of the tau neutrino is many orders of magnitude weaker than for any
other known neutrino. We discuss possible modifications of the minimal standard
model such that electric charge is quantized classically.


title: Neutrino oscillations and the exact parity model

abstract:
  We re-examine neutrino oscillations in exact parity models. Previously it was
shown in a specific model that large neutrino mixing angles result. We show
here that this is a general result of neutrino mixing in exact parity models
provided that the neutrino mass matrix is real. In this case, the effects of
neutrino mixing in exact parity models is such that the probability of a given
weak eigenstate remaining in that eigenstate averages to {\it less} than a half
when averaged over many oscillations. This result is interesting in view of the
accumulating evidence for a significant deficit in the number of solar
neutrinos. It may also be of relevance to the atmospheric neutrino anomaly.


title: A note on Koide's lepton mass relation

abstract:
  Koide has pointed out that the mass relation $m_e + m_{\mu} + m_{\tau} = {2
\over 3}(\sqrt{m_e} + \sqrt{m_{\mu}} + \sqrt{m_{\tau}})^2 $ is consistent with
the most recent measurements of the tau lepton mass. We point out that this
relation has a geometric interpretation.