title: Relating the scalar flavour-changing neutral couplings to the CKM matrix

abstract:
  We build a class of two-Higgs-doublet models in which the flavour-changing
couplings of the neutral scalars are related in an exact way to elements of the
quark mixing matrix. In this framework, we explore the different possibilities
for CP violation and find some interesting scenarios, like a realization of the
superweak idea without CP violation in the $B$-meson system. In another
scenario the neutral scalars can be relatively light, and their contributions
to the $B^0$--$\bar{B}^0$ transitions can alter the standard-model predictions
for CP violation in that system.


title:
QCD Corrections to Heavy Quark Pair Production in Polarized
  $\gamma\gamma$ Collisions and the Intermediate Mass Higgs Signal

abstract:
  Perturbative QCD one-loop corrections to the cross sections of the $b\bar b$
$(c\bar c)$ quark pair production in polarized photon-photon collisions, as
well as cross sections of the radiative processes photon-photon ->$b\bar b
g$,$c\bar c g$ leading to two- and three-jet final states are calculated. It is
shown that the signal from the intermediate mass Higgs boson is observable and
precise measurements of the Higgs boson two-photon width are possible at a
photon-photon collider, although the statistical significance is substantially
reduced with respect to the tree level calculations. We demonstrate that
virtual corrections are of the same order or larger than the Born contribution
in the $J_z=0$ channel at high energy for small values of the cutoff $y_{cut}$,
separating two-jet from three-jet topologies. The nature of these large
corrections is elucidated. For $b\bar b$ pair production at
$\sqrt{s_{\gamma\gamma}}\sim 100$~GeV and for small values of $y_{cut}\leq
0.04$ the higher order resummation of double logarithmic terms ${\cal
O}\left(\alpha_s m_b^2/s\ln^2(s/m_b^2)\right)$ is needed.


title:
Heavy quarks in charged-current deep inelastic scattering: a systematic
  phenomenological study

abstract:
  We present a systematic QCD analysis of the strange--charm and bottom--top
contributions to transverse and longitudinal structure functions in
charged--current deep inelastic scattering. Various ${\cal O}(\alpha_s^1)$
schemes are studied and compared. The dependence of their predictions on the
factorization scale $\mu^2$ is investigated. The theoretical uncertainties
resulting from the choice of the scheme and of $\mu^2$ are estimated.


title:
$^1P_1$ charmonium state decay into $p \bar p$ in QCD models including
  constituent quark mass corrections

abstract:
  Stimulated by the experimental observation, made by the E760 Collaboration at
Fermilab, of the $^1\!P_1$ state of charmonium resonantly formed in $p\,\bar p$
annihilation, we perform a calculation of the decay width for the $^1\!P_1\to
p\,\bar p$ process. To this end, we employ a phenomenological model which adds
constituent quark mass corrections to the usual massless QCD models for
exclusive processes. For massless models, in fact, the process under
consideration is forbidden by the so-called helicity selection rules, while it
is allowed in our extended model. We find $\Gamma(^1\!P_1\to p\,\bar p)$ to be
in the range $1-10$ eV. We also compare our results with previous, indirect
estimates, based on QCD multipole expansion models.


title:
Upper bound on all products of R-parity violating couplings $\lambda'$
  and $\lambda''$ from proton decay

abstract:
  We prove that {\em any} product of R-parity violating couplings $\lambda'$
(L-violating) and $\lambda''$ (B-violating) can be strongly restricted by
proton decay data. For any pair $\lambda'$ and $\lambda''$ the decay exists at
least at one loop level. For squark masses below 1 TeV we find the conservative
bounds $|\lambda' \cdot \lambda''| < 10^{-9}$ in absence of squark flavor
mixing, and $|\lambda' \cdot \lambda''| < 10^{-11}$ when this mixing is taken
into account. We study the dependence of the bounds on the flavor basis in
which R-parity breaking couplings are determined.


title: Flavour and Spin of the Proton and the Meson Cloud

abstract:
  We present a complete set of formulas for longitudinal momentum distribution
functions (splitting functions) of mesons in the nucleon. It can be applied in
the framework of convolution formalism to the deep-inelastic structure
functions (quark distributions) of the nucleon viewed as a system composed of
virtual 'mesons' and 'baryons'. Pseudoscalar and vector mesons as well as octet
and decuplet baryons are included. In contrast to many approaches in the
literature the present approach ensures charge and momentum conservation by the
construction. We present not only spin averaged splitting functions but also
helicity dependent ones, which can be used to study the spin content of the
nucleon. The cut-off parameters of the underlying form factors for different
vertices are determined from high-energy particle production data. This
information allows one to calculate the flavour and spin content of the
nucleon. The value of the Gottfried Sum Rule obtained from our model (S_G =
0.224) nicely agrees with that obtained by the NMC. In addition, we calculate
the x-dependence of the \bar d - \bar u asymmetry and get an impressive
agreement with a recent fit of Martin-Stirling-Roberts. The calculated axial
coupling constants for semileptonic decays of the octet baryons agree with the
experimental data already with SU(6) wave function for the bare nucleon.
Although we get improvements for the Ellis-Jaffe Sum Rules for the proton and
neutron in comparison to the naive quark model, the MCM is not sufficient to
reproduce the experimental data.


title:
On the impossibility to distinguish MSW transitions from vacuum
  oscillations for neutrino maximal mixing

abstract:
  We show in a simple and general way that MSW resonant transitions for solar
neutrinos are not observable in the case of maximal mixing among any number of
neutrino generations.


title: Mixing Renormalization in Majorana Neutrino Theories

abstract:
  The renormalization of general theories with inter-family mixing of Dirac
and/or Majorana fermions is studied at the one-loop electroweak order. The
phenomenological significance of the mixing-matrix renormalization is
discussed, within the context of models based on the SU(2)_L x U(1)_Y gauge
group. The effect of radiative neutrino masses present in these models is
naturally taken into account in this formulation. As an example, charged-lepton
universality in pion decays is investigated in the heavy- neutrino limit.
Non-decoupling heavy-neutrino effects induced by mixing renormalization are
found to considerably affect the predictions in these new-physics scenarios.


title: String Gauge Unification and Infra-red Fixed Points in MSSM+X Models

abstract:
  In order to achieve gauge unification at the string scale M_X sim 5.10^17 GeV
in the minimal supersymmetric standard model (MSSM) it is necessary to add
extra gauge non-singlet representations at an intermediate scale M_I<M_X,
leading to a class of models which we refer to as MSSM+X models. We perform a
detailed analysis of a large class of MSSM+X models and find that the number of
(3,1) representations added must be greater than the total of the number of
(3,2) and (1,2) representations. Predictions of M_I, M_X and alpha(M_X) are
obtained for models with up to 5 extra vector representations than the MSSM\@.
Upper bounds on the U(1) string gauge normalisation k_1 and the sum of the
squares of the hypercharge assignments of the extra matter are also obtained
for the models. We also study the infra-red fixed point behaviour of the top
quark Yukawa coupling in a large class of MSSM+X models and find that the low
energy MSSM quasi-fixed point prediction of the top quark mass is more likely
to be realised in these theories than in the MSSM. In other words the top quark
tends to be heavier in MSSM+X models than in the MSSM. The implementation of a
U(1)_X family symmetry into MSSM+X models to account for the Standard Model
fermion masses is discussed and a particular viable model is presented.


title: Speculations on ALEPH's Dijet Enhancement

abstract:
  We interpret the dijet enhancement reported by the ALEPH collaboration in the
process $e^+e^- \rightarrow $ 4 jets as being due to the production of a pair
of bottom squarks, followed by their R-parity violating decays into pairs of
light quarks. Constraints on this speculative interpretation are examined. Some
of the consequences of our hypothesis are drawn within the context of softly
broken supersymmetry.


title: Higgs Boson And $W_L W_L$ Scattering At $e^-e^-$ Colliders

abstract:
  We discuss the Standard-Model Higgs boson production in the channels
$e^-e^-\to e^-e^- H$, $e^-\nu W^- H$, and $e^-e^- ZH We also illustrate the
enhancements in the $W^-W^-$ cross section that would result from a
strongly-interacting Higgs sector or from a $H^{--}$ resonance in a doublet +
triplet scalar field model.


title:
First Lattice Study of the Form Factors A_0 and A_3 in the Decay Bbar^0
  to rho^+ l^- nubar_l

abstract:
  We report on a lattice calculation of the form factors A_0 and A_3 for the
pseudoscalar to vector meson semileptonic decay Bbar^0 to rho^+ l^- nubar_l. We
find that resonant (or pole-type) contributions alone are unable to describe
these two form factors simultaneously. For the quantity A_0(q^2=0), which is
important phenomenologically for the determination of |Vub|, we extract a range
of values, A_0(q^2=0) = (0.16--0.35) +0.09-0.06, where the range is due to
systematic uncertainty and the quoted error is statistical. We have also
determined A_2(q^2=0) = 0.28 +0.09-0.06 +0.04-0.05.


title: Nonperturbative dissipation in QCD jets

abstract:
  The phenomenological energy dissipation in QCD jets evolution with colour
coherence is considered and the corresponding modified parton multiplicity and
distribution function are computed.


title: Event Generators for Discovery Physics

abstract:
  Review of Monte Carlo event generators for signals of new particles at LEP2.
The areas covered include SUSY, HIGGS and Leptoquarks.


title:
Majorana Neutrinos as the Dark Matters in the Cold plus Hot Dark Matter
  Model

abstract:
  A simple model of the Majorana neutrino with the see-saw mechanism is
studied, assuming that two light neutrinos are the hot dark matters with equal
mass of 2.4 eV in the cold plus hot dark matter model of cosmology. We find
that the heavy neutrino, which is the see-saw partner with the remaining one
light neutrino, can be the cold dark matter, if the light neutrino is exactly
massless. This cold dark matter neutrino is allowed to have the mass of the
wide range from 5.9 x 10^2 eV to 2.2 x 10^7 eV.


title: Multiplicity Distributions in QCD and $\lambda\varphi^3_6$-model

abstract:
  It is shown that QCD with vector gluons predicts drastically different
multiplicity distributions compared to the scalar $\lambda\varphi^3$-model (in
6 dimensions). In particular, the QCD predicted minimum of cumulant moments of
the distributions at ranks about $5\div7$ does not reveal itself in the scalar
model. The oscillations at higher ranks survive only. Thus, the experimental
fact of that minimum at ranks about $5\div7$ supports the vector nature of
gluons and singular kernels in QCD and gluodynamics.


title: On Supersymmetric b-tau Unification, Gauge Unification, and Fixed Points

abstract:
  The equality assumption of the b and tau Yukawa couplings at the
grand-unification scale can strongly constrain the allowed parameter space of
supersymmetric models. We examine the constraints in the case that there is a
discrepancy > 10% in the gauge coupling unification assumption (which
necessarily implies large perturbations at the grand scale). The constraints
are shown to diminish in that case [most significantly so if alpha_{s}(M_{Z})
\approx 0.11]. In particular, the requirement that the t Yukawa coupling,
h_{t}, is near its quasi-fixed point may not be necessary. We discuss the
colored-triplet threshold as a simple example of a source for the
discrepancies, and comment on its possible implications. In addition, we point
out that supersymmetric (as well as unification-scale) threshold corrections to
h_{t} shift the fixed-point curve in the m_{t} - \tan\beta plane. The
implications for the prediction of the Higgs boson mass are briefly discussed.


title: Searches For New Physics

abstract:
  Review of prospects for discovery of new physics signals at LEP2. The areas
covered include SUSY, exotic fermions, BESS models, leptoquarks, virtual
effects and CP violating observables.


title: The Top Cross Section in Hadronic Collisions

abstract:
  We reexamine the top quark production cross section at the Tevatron and LHC,
in the light of recent progress on the resummation of logarithmic soft gluon
corrections. We find that resummation effects are much smaller than previously
thought. We also compute Coulombic threshold effects, and find them negligible.
We update the discussion of uncertainties due to scale dependence, the value of
the strong coupling constant, and the parton density parametrization. Our
current best estimate of the top production cross section at the Tevatron and
its error is $\sigma(\mt=175\,{\rm GeV})=4.75{+0.73\atop-0.62}$.


title: A Flipped SO(10) GUT Model and the Fermion Mass Hierarchy

abstract:
  We present a viable flipped version of the SO(10) model consistent with the
phenomenological requirements of having a non-trivial quark mixing matrix,
natural doublet-triplet splitting, and a single pair of light electroweak Higgs
doublet scalar bosons. In the presence of suitable non-renormalizable
superpotential terms the model can reproduce the hierarchy observed in quark
masses and mixings as well as an acceptable neutrino mass generated via the
seesaw mechanism needed to explain dark matter and solar neutrino data.


title:
Application of 'Optimised' Perturbation Theory to Determination of
  alpha_s(M_Z^2) from Hadronic Event Shape Observables in e+e- Annihilation

abstract:
  We have applied so-called `optimised' perturbation theory to resolve the
renormalisation-scale (mu) ambiguity of exact O(alpha_s^2) QCD calculations of
event shape observables in e+e- --> hadrons. We fitted the optimised
predictions for 15 observables to hadronic Z0 decay data from the SLD
experiment to determine alpha_s(M_Z^2). Comparing with results using the
physical scale mu = M_Z we found no reduction in the scatter among
alpha_s(M_Z^2) values from the 15 observables, implying that the O(alpha_s^2)
predictions with optimised scales are numerically no closer to the exact
all-orders results than those with the physical scale.


title:
Implications of the Strange Spin of the Nucleon for the Neutron Electric
  Dipole Moment in Supersymmetric Theories

abstract:
  Supersymmetric model contributions to the neutron electric dipole moment
arise via quark electric dipole moment operators, whose matrix elements are
usually calculated using the Naive Quark Model (NQM). However, experiments
indicate that the NQM does not describe well the quark contributions $\Delta q$
to the nucleon spin, and so may provide misleading estimates of electric dipole
operator matrix elements. Taking the $\Delta q$ from experiment, we indeed find
consistently smaller estimates of the neutron electric dipole moment for given
values of the supersymmetric model parameters. This weakens previous
constraints on CP violation in supersymmetric models, which we exemplify
analytically in the case where the lightest supersymmetric particle (LSP) is a
$U(1)$ gaugino $\tilde{B}$, and display numerically for other LSP candidates.


title: Possible Candidates for SUSY E$_6$ GUT with an Intermediate Scale

abstract:
  We study the possibility of an intermediate scale existing in supersymmetric
E$_6$ grand unified theories. The intermediate scale is demanded to be around
$10^{12}$ GeV so that neutrinos can obtain masses suitable for explaining the
experimental data on the deficit of solar neutrinos with the
Mikheev-Smirnov-Wolfenstein solution and the existence of hot dark matter. We
require that at the intermediate scale, a certain symmetry breakdown to the
Standard Model symmetry. We show that only a few E$_6$ subgroups are likely to
be realized as the intermediate symmetry, though there are many candidates for
the intermediate symmetry in E$_6$ GUT.


title: Testing the meson cloud in the nucleon in Drell-Yan processes

abstract:
  We discuss the present status of the \bar u-\bar d asymmetry in the nucleon
and analize the quantities which are best suited to verify the asymmetry. We
find that the Drell-Yan asymmetry is the quantity insensitive to the valence
quark distributions and very sensitive to the flavour asymmetry of the sea. We
compare the prediction of the meson cloud model with different experimental
data including the Fermilab E772 data and recent data of the NA51 Collaboration
at CERN and make predictions for the planned Drell-Yan experiments.


title: The QCD beta-function at O(1/N_f)

abstract:
  The leading order coefficients of the beta-function of QCD are computed in a
large N_f expansion. They are in agreement with the three loop MSbar
calculation. The method involves computing the anomalous dimension of the
operator (G^2_{mu nu})^2 at the d-dimensional fixed point in the non-abelian
Thirring model to which QCD is equaivalent in this limit. The effect the
O(1/N_f) corrections have on the location of the infrared stable fixed point
for a range of N_f is also examined.


title:
Residual New Physics Effects in $e^+e^-$ and $\gamma\gamma$ Collisions
  at NLC

abstract:
  We report on a set of studies concerning the description of New Physics (NP)
effects characterized by a scale much higher than the electroweak scale. We
concentrate on the residual effects described by an effective lagrangian
involving only bosonic fields and restrict to the case that the Higgs field is
described linearly, so that the Higgs particle exists. It has already been
emphasized that this lagrangian may be represented by eight $dim=6$ operators;
namely the blind CP-conserving operators $\O_W$, $\O_{B\Phi}$, $\O_{W\Phi}$,
$\O_{UB}$, $\O_{UW}$, the ''superblind'' ${\cal O}_{\Phi 2}$ and the two
CP-violating ones $\ol{\O}_{UB}$ and $\ol{\O}_{UW}$. To each operator and for
any given value of its coupling, we associate an unambiguous NP scale
determined by the energy where unitarity is saturated. Our study of the
possible NP tests realizable at a future linear $e^+e^-$ collider concentrates
on $(e^+e^-\to HZ ~,~ H\gamma)$, and on $\gamma\gamma$ collisions producing
boson pairs ($\gamma\gamma \to W^+W^-$, $ZZ$, $Z\gamma$, $\gamma\gamma$, $HH$),
or a single Higgs ($\gamma\gamma \to H$). The sensitivities to the various
operators involved in the effective lagrangian are estimated. We find that the
testable NP scales vary from a few tens of TeV in the boson pair processes, up
to 65 TeV in single H production. Ways to disentangle the various operators are
also proposed. In this respect a comparison of the NP effects in the various
boson pair processes, like \eg\@ a comparison of $e^+e^-\to HZ$ versus
$e^+e^-\to H\gamma$, should be very fruitful. This is applied also to the study
of the Higgs branching ratios, and especially the ratio
$\Gamma(H\to\gamma\gamma)/\Gamma (H\to\gamma Z)$.


title:
Short-baseline neutrino oscillations and neutrinoless double-beta decay
  in the framework of three neutrino mixing and a mass hierarchy

abstract:
  We have analyzed the results of the latest terrestrial neutrino oscillation
experiments in the framework of a model with mixing of three massive neutrinos
and a neutrino mass hierarchy ($ m_1 << m_2 << m_3 $). In this model,
oscillations of the terrestrial neutrinos are characterized by three
parameters, $ \Delta m^2 = m_3^2 - m_1^2 $ and the squared moduli of the two
mixing matrix elements $U_{e3}$ and $U_{\mu3}$. Using the results of
disappearance experiments and solar neutrino experiments, it is shown that only
two regions of possible values of $|U_{e3}|^2$ and $|U_{\mu3}|^2$ are allowed:
I. $|U_{e3}|^2$ and $|U_{\mu3}|^2$ are both small and II. $|U_{e3}|^2$ is small
and $|U_{\mu3}|^2$ is large. If the mixing parameters are in the region I, $
\nu_\mu <-> \nu_e $ oscillations are suppressed. In this case the LSND
indication in favor of $ \nu_\mu <-> \nu_e $ oscillations is not compatible
with the negative results of all other experiments. If the mixing parameters
are in the region II, $ \nu_e <-> \nu_\tau $ oscillations are strongly
suppressed. If massive neutrinos are Majorana particles, our analysis shows
that neutrinoless double-beta decay could be observed in the experiments of the
next generation only if the mixing parameters are in the region I.


title: Topological Inflation, without the Topology

abstract:
  We extend the `topological inflation' of Linde and Vilenkin to {\em unstable}
monopoles. This allows the monopole to decay; not inflating eternally, as
topological inflation demands. Such a situation happens naturally in some Grand
Unified Theories --- such as supersymmetric flipped-$SU(5)$. We analyse
analytically the dynamics of inflating monopoles to determine the equations
governing the expansion, additionally recovering the bound on the scale of
symmetry breaking found numerically by Sakai {\em et. al.} The latter half of
this paper is devoted to the Cosmology of inflating unstable monopoles ---
which is an example of an inhomogeneous cosmology. We describe how such a
monopole may be formed and how long it inflates for --- finding it to be a
random process. We then derive how cosmological parameters, such as density and
temperature, are distributed at the end of inflation, and how the Universe
reheats as the monopole decays. The general conclusion of this work is that
such inflation creates a local region of relatively flat, homogenous and
isotropic Universe surrounded by pre-GUT matter.


title: SU(3) Decomposition of Two-Body B Decay Amplitudes

abstract:
  We present the complete flavor SU(3) decomposition of decay amplitudes for
decays of the triplet (B^+_u, B^0_d, B^0_s) of B mesons nonleptonically into
two pseudoscalar mesons. This analysis holds for arbitrarily broken SU(3) and
can be used to generate amplitude relations when physical arguments permit one
to neglect or relate any of the reduced amplitudes.


title: Higgs Masses and $CP$ Violation in SUSY Models

abstract:
  Though the mass of Higgs particle is the parameter determined by the
experiment in the standard model (SM), SUSY models have rather predictive power
for the lightest Higgs mass, and its upper bound in some SUSY models are close
to the observable region in LEP2. The upper bound of the lightest Higgs mass is
analysed systematically on the basis of the $CP$ violation in the minimal and
the next minimal supersymmetric standard model (MSSM and NMSSM). In the
explicit $CP$ violation case, the mass bound is large around $130 \sim 160$ GeV
in both models. In the spontaneous $CP$ violation case induced by the radiative
effects, the lightest Higgs mass upper bound is about $52$ GeV and sum of two
light neutral Higgs should be around $O$(100 GeV) in the NMSSM in contrast to
the one in the MSSM which implies about 6 GeV. This model gives the interesting
predictions for the neutron electric dipole moment.


title: Higgs boson production under the resonance threshold at LEP II

abstract:
  We consider the possibility of Higgs boson detection at LEP II under the
resonance threshold ($\sqrt{s}<m_H+m_Z$) in the framework of complete tree
level approach to the calculation of the $e^+ e^- \rightarrow \nu \bar \nu b
\bar b$ amplitude, simulating b-quark fragmentation to hadrons and taking into
account typical detector properties. At the energy below the $2m_Z$ threshold
$\sqrt{s}=$ 175 GeV Higgs boson production under the $m_H+m_Z$ threshold is
practically background free.


title:
Symmetry Breaking and Generational Mixing in Topcolor--Assisted
  Technicolor

abstract:
  Topcolor--assisted technicolor provides a dynamical explanation for
electroweak and flavor symmetry breaking and for the large mass of the top
quark without unnatural fine tuning. A major challenge is to generate the
observed mixing between heavy and light generations while breaking the strong
topcolor interactions near~$1\,\tev$. I argue that these phenomena, as well as
electroweak symmetry breaking, are intimately connected and I present a
scenario for them based on nontrivial patterns of technifermion condensation. I
also exhibit a class of models realizing this scenario. This picture leads to a
rich phenomenology, especially in hadron and lepton collider experiments in the
few hundred GeV to few TeV region and in precision electroweak tests at the
$Z^0$, atomic parity violation, and polarized M{\o}ller scattering.


title: Spin asymmetries in diffractive high-energy reactions

abstract:
  The analysis of some effects caused by the spin--dependent pomeron couplings
is presented. It is shown that the structure of pomeron--proton and
quark--pomeron couplings can be tested in future polarized experiments on
elastic $pp$ reactions and diffractive $Q \bar Q$ production.


title: Color-octet mechanism in $\gamma + p \to J/\psi + X$

abstract:
  Photoproduction of $J/\psi$ is considered including the color-octet
contributions from the various partial wave states, $^{2S+1}L_J$ = $^1S_0$,
$^3S_1$ and $^3P_J$. The production cross section depends on three new
nonperturbative parameters defined in NRQCD, called the color-octet matrix
elements. Using the color-octet matrix elements determined by fitting the
$J/\psi$ production at the Tevatron, we find that the color-octet($c\bar{c})
_{8}({^1S_0}~{\rm and~}~{^3P_J})$ contributions to the $J/\psi$
photoproductions at the fixed target experiments and HERA are too large
compared to the data on $\sigma (\gamma + p \to J/\psi +X)$ in the forward
direction, the $z$ distribution of $J/\psi$. The $P_T^2$ distribution of
$J/\psi$ and the total inelastic $J/\psi$ production rate as a function of
$\sqrt{s_ {\gamma p}}$ are predicted including color-octet contributions. We
also briefly digress on the $B \to J/\psi + X$ and observe the similar
situation. This may be an indication that the color-octet matrix elements
determined from the $J/\psi$ production at the Tevatron, especially $<0 | {\cal
O}_{8}^{\psi} ({^1S_0}) | 0>$ and $<0 | {\cal O}_{8}^{\psi} ({^3P_J}) | 0>$,
might have been overestimated by an order of magnitude.


title: Studying the Higgs Potential via $e^+e^- \to Zhh$

abstract:
  The physics prospect at future linear $e^+e^-$ colliders for the study of the
Higgs triple self-coupling via the process of $e^+e^-$ $\rightarrow Zhh$ is
investigated. The measurement of this cross section leads us to the first
non-trivial information on the Higgs potential.
  We found that the Standard Model and the model without the Higgs
self-coupling can be distinguished at the level of one standard deviation for a
rather light Higgs mass with 100 fb$^{-1}$ integrated luminosity.
  In the MSSM, the cross section is enhanced if the production of at least one
of heavy Higgs bosons ($H$ or $A$) and its subsequent decay ($H \rightarrow
hh$, $A \rightarrow Zh$) are kinematically allowed. When such processes are not
allowed, the cross section in the region of small $m_A$ is significantly
suppressed relative to the SM cross section.


title: Universality near zero virtuality

abstract:
  In this paper we study a random matrix model with the chiral and flavor
structure of the QCD Dirac operator and a temperature dependence given by the
lowest Matsubara frequency. Using the supersymmetric method for random matrix
theory, we obtain an exact, analytic expression for the average spectral
density. In the large-n limit, the spectral density can be obtained from the
solution to a cubic equation. This spectral density is non-zero in the vicinity
of eigenvalue zero only for temperatures below the critical temperature of this
model. Our main result is the demonstration that the microscopic limit of the
spectral density is independent of temperature up to the critical temperature.
This is due to a number of `miraculous' cancellations. This result provides
strong support for the conjecture that the microscopic spectral density is
universal. In our derivation, we emphasize the symmetries of the partition
function and show that this universal behavior is closely related to the
existence of an invariant saddle-point manifold.


title: Determing the CP Nature of a Neutral Higgs Boson at the LHC

abstract:
  We demonstrate that certain weighted moments of $t\anti t \h$ production can
provide a determination of the CP nature of a light neutral Higgs boson
produced and detected in this mode at the CERN LHC.


title: Soft Colour Interactions and the Diffractive Structure Function

abstract:
  We discuss our model for soft colour interactions and present results on the
diffractive structure function $F_2^D(\beta,x_\pom,Q^2)$ and inclusive
transverse energy flows, which agree with available HERA data.


title: Automatic CP Invariance and Flavor Symmetry

abstract:
  The approximate conservation of $CP$ can be naturally understood if it arises
as an automatic symmetry of the renormalizable Lagrangian. We present a
specific realistic example with this feature. In this example, the global
Peccei-Quinn symmetry and gauge symmetries of the model make the renormalizable
Lagrangian $CP$ invariant but allow non zero hierarchical masses and mixing
among the three generations. The left-right and a horizontal $U(1)_H$ symmetry
is imposed to achieve this. The non-renormalizable interactions invariant under
these symmetries violate $CP$ whose magnitude can be in the experimentally
required range if $U(1)_H$ is broken at very high, typically, near the grand
unification scale.


title: How to measure the pion structure function at HERA

abstract:
  We suggest a method of determination of the pion structure function down to x
\simeq 10^{-4} based on semi-exclusive deep inelastic scattering off protons.
The idea is to exploit the nonperturbative \pi N$ and \pi\Delta Fock components
of the nucleon, which contribute significantly to deep inelastic scattering and
dominate the fragmentation of protons into fast neutrons and deltas. The
intrinsic factorization properties of the semi-exclusive cross section give a
good test for the validity of this approach.


title:
Fast Antibaryon Production in $pp$ Collisions as a Result of String
  Fusion

abstract:
  The inclusion of string fusion in Dual Parton Model results in the appearance
of diquark-antidiquark pairs in the sea with comparatively large Feynman-$x$.
Such antidiquarks can fragment into fast antibaryons, thus increasing several
times the corresponding yields in high energy $pp$ collisions for $x_F \sim 0.8
\div 0.9$. String fusion also results in an unusual dependence of inclusive
spectra on the multiplicity of secondaries. Some numerical estimations are
presented.


title: Dynamical mass matrices from moduli fields

abstract:
  We review recent work on the structure of the fermion mass matrices in
supergravity effective superstrings. They are generally given at low energy by
non-trivial functions of the gauge singlet moduli fields. Interesting
structures appear in particular if they are homogeneous functions of zero
degree in the moduli. In this case we find Yukawa matrices very similar to the
ones obtained by imposing a $U(1)$ family symmetry to reproduce the observed
hierarchy of masses and mixing angles. The role of the $U(1)$ symmetry is
played here by the modular symmetry. The Flavor Changing Neutral Currents
effects at the Planck scale coming from the soft terms are identically zero. A
dynamical scenario is discussed which allow to generate the observed
hierarchies.


title: Evolution of Inhomogeneous Condensates after Phase Transitions

abstract:
  Using the O(4) linear $\sigma$ model, we address the topic of non-equilibrium
relaxation of an inhomogeneous initial configuration due to quantum and thermal
fluctuations. The space-time evolution of an inhomogeneous fluctuation of the
condensate in the isoscalar channel decaying via the emission of pions in the
medium is studied within the context of disoriented chiral condensates. We use
out of equilibrium closed time path methods in field theory combined with the
amplitude expansion. We give explicit expressions for the asymptotic space-time
evolution of an initial inhomogeneous configuration including the contribution
of thresholds at zero and non-zero temperature. At non-zero temperature we find
new relaxational processes due to thermal cuts that have no counterpart in the
homogeneous case. Within the one-loop approximation, we find that the space
time evolution of such inhomogeneous configuration out of equilibrium is
effectively described in terms of a rapidity dependent temperature
$T(\vartheta)=T/\cosh[\vartheta]$ as well as a rapidity dependent decay rate
$\Gamma(\vartheta, T(\vartheta))$. This rate is to be interpreted as the
production minus absorption rate of pions in the medium and approaches the zero
temperature value at large rapidities. An initial configuration localized on a
bounded region spreads and decays in spherical waves with slower relaxational
dynamics at large rapidity.


title: An improved cosmological bound on the tau-neutrino mass

abstract:
  We consider the influence of non-equilibrium electronic neutrinos (and
anti-neutrinos) on the neutron-to-proton ratio. These neutrinos would come from
massive $\nu_\tau$ annihilations $\bar \nu_\tau \nu_\tau \rightarrow \bar \nu_e
\nu_e$. For sufficiently large $\nu_\tau$ masses this new effect would strongly
enhance the (n/p)-ratio, leading to a very stringent bound on the $\nu_\tau$
mass, even adopting a rather weak upper bound on the effective number on
neutrino species during nucleosynthesis.


title:
Multiple Production of MSSM Neutral Higgs Bosons at High--Energy
  $e^+e^-$ Colliders

abstract:
  The cross sections for the multiple production of the lightest neutral Higgs
boson at high--energy $e^+ e^-$ colliders are presented in the framework of the
Minimal Supersymmetric extension of the Standard Model (MSSM). We consider
production through Higgs--strahlung, associated production of the scalar and
the pseudoscalar bosons, and the fusion mechanisms for which we will use the
effective longitudinal vector--boson approximation. These cross sections allow
one to determine trilinear Higgs couplings $\lambda_{Hhh}$ and $\lambda_{hhh}$,
which are theoretically predicted by the Higgs potential.


title: The Search for the Quark-Gluon Plasma

abstract:
  We provide an overview of the present understanding of the transition from
hadrons to a quark-gluon plasma, its signatures, and the experimental results
so far. We discuss results of numerical simulations of the lattice gauge theory
and critically evaluate the various observables that have been proposed as
signatures of the QCD phase transition. We place the existing data from
relativistic heavy ion experiments at the Brookhaven AGS and CERN SPS into
perspective and provide an overview of the techniques and strategies that will
be employed in the search for the quark-gluon plasma at heavy ion colliders,
such as RHIC and the LHC.


title: Spin, Twist and Hadron Structure in Deep Inelastic Processes

abstract:
  These notes provide an introduction to polarization effects in deep inelastic
processes in QCD. We emphasize recent work on transverse asymmetries,
subdominant effects, and the role of polarization in fragmentation and in
purely hadronic processes. After a review of kinematics and some basic tools of
short distance analysis, we study the twist, helicity, chirality and
transversity dependence of a variety of high energy processes sensitive to the
quark and gluon substructure of hadrons.


title: Quantum effects in radiation on short bunches

abstract:
  The radiation caused by particles of one bunch in the collective
electromagnetic field of the short oncoming bunch is studied. Quantum effects
are calculated for the spectrum of radiated photons. Using this spectrum, the
dependence of the relative energy loss delta on a quantum parameter kappa is
dicussed. It is shown that the behaviour of delta changes considerably with the
increase of that parameter. In the classical regime (kappa << 1) the energy
loss is proportional to the incoming particle energy, while in the extreme
quantum regime (kappa >> 1) the energy loss becomes a constant. The coherent
e+e- pair production for gamma-e colliders as cross-channel to CBS is
considered.


title: Weakly-Coupled Higgs Bosons

abstract:
  We review the search for the standard Higgs boson, the Higgs bosons of the
supersymmetric standard model, and Higgs bosons from a variety of other models
at present and future colliders.


title:
Supersymmetric analysis and predictions based on the CDF ee\gamma\gamma
  + missing E_T event

abstract:
  We have analyzed the single $\eegg + \slashchar{E}_T$ event at CDF and found
that the expected rate and kinematics are consistent with selectron pair
production. We consider two classes of general low-energy supersymmetric
theories, where either the lightest neutralino (``neutralino LSP'' scenario) or
the gravitino (``light gravitino'' scenario) is the lightest supersymmetric
particle. The parameter space of the supersymmetric Lagrangian is tightly
constrained by the kinematics of the event and the branching ratios for the
necessary decay chain of the selectron. We identify a region of the parameter
space satisfying all low-energy constraints, and consistent with the selectron
interpretation of the $ee\gamma\gamma + \Et$ event. We discuss other
supersymmetric processes at Fermilab Tevatron and at CERN LEP in both scenarios
that could confirm or exclude a supersymmetric explanation of the event, and
that could distinguish between the neutralino LSP and the light gravitino
scenarios.


title: The Pion Mass Formula

abstract:
  The often used Gell-Mann-Oakes-Renner mass formula for Nambu-Goldstone (NG)
bosons in QCD, such as the pions, involves the condensate $<\overline{q}q>$,
$f_{\pi}$ and the quark current masses. Within the context of the Global Colour
Model (GCM) for QCD a manifestly different formula was recently found by Cahill
and Gunner. Remarkably Langfeld and Kettner have shown the two formula to be
equivalent. Here we note that the above recent analyses refer to the
constituent pion and not the exact pion, even within the GCM. Further we
generalise the Langfeld-Kettner identity to include the full response of the
constituent quark propagators to the presence of a non-zero (and running) quark
current mass.


title:
The relativistic two-body potentials of constraint theory from summation
  of Feynman diagrams

abstract:
  The relativistic two-body potentials of constraint theory for systems
composed of two spin-0 or two spin-1/2 particles are calculated, in
perturbation theory, by means of the Lippmann-Schwinger type equation that
relates them to the scattering amplitude. The cases of scalar and vector
interactions with massless photons are considered. The two-photon exchange
contributions, calculated with covariant propagators,are globally free of
spurious infra-red singularities and produce at leading order O(\alpha^4)
effects that can be represented in three-dimensional x-space by local
potentials proportional to (\alpha/r)^2. Leading contributions of n-photon
exchange diagrams produce terms proportional to (\alpha/r)^n. The series of
leading contributions are summed. The resulting potentials are functions, in
the c.m. frame, of r and of the total energy. Their forms are compatible with
Todorov's minimal substitution rules proposed in the quasipotential approach.


title:
1/m Corrections to Heavy Baryon Masses in the Heavy Quark Effective
  Theory Sum Rules

abstract:
  The 1/m corrections to heavy baryon masses are calculated from the QCD sum
rules within the framework of the heavy quark effective theory. Numerical
results for the heavy baryons are obtained. The implications of the results are
discussed.


title: Current, Pion and Photon Transitions between Heavy Baryons

abstract:
  I discuss the structure of current-induced bottom baryon to charm baryon
transitions, and the structure of pion and photon transitions between heavy
charm or bottom baryons in the Heavy Quark Symmetry limit as
$m_Q\rightarrow\infty$. The emphasis is on the structural similarity of the
Heavy Quark Symmetry predictions for the three types of transitions. The
discussion involves the ground state $s$-wave heavy baryons as well as the
excited $p$-wave heavy baryon states. Using a constituent quark model picture
for the light diquark system with an underlying $SU(2N_f)\otimes O(3)$ symmetry
one arrives at a number of new predictions that go beyond the Heavy Quark
Symmetry predictions.


title: Temperature and Density Effects on the Nucleon Mass Splitting

abstract:
  The finite temperature and finite density dependence of the neutron-proton
mass difference is analysed in a purely hadronic framework where the
$\rho-\omega $ mixing is crucial for this isospin symmetry breakdown. The
problem is handled within Thermo Field Dynamics. The present results,
consistent with partial chiral and charge symmetry restoration, improve the
experimental data fit for the energy difference between mirror nuclei.


title:
Improved Evaluation of the Next-Next-To-Leading Order QCD Corrections to
  the e+e- Annihilation Into Hadrons

abstract:
  The next-next-to-leading order QCD corrections to the e+e- annihilation into
hadrons are considered. The stability of the predictions with respect to change
of the renormalization scheme is discussed in detail for the case of five, four
and three active quark flavors. The analysis is based on the recently proposed
condition for selecting renormalization schemes according to the degree of
cancellation that they introduce in the expression for the scheme invariant
combination of the expansion coefficients. It is demonstrated that the scheme
dependence ambiguity in the predictions obtained with the conventional
expansion is substantial, particularly at lower energies. It is shown however,
that the stability of the predictions is greatly improved when QCD corrections
are evaluated in a more precise way, by utilizing the contour integral
representation and calculating numerically the contour integral.


title:
Factorization properties of the diffraction dissociation of longitudinal
  photons

abstract:
  We develop the pQCD description of the diffraction dissociation (DD) of
longitudinal photons. We demonstrate that the longitudinal diffractive
structure function does not factor into the flux of pomerons and the partonic
structure function of the pomeron, thus defying the usually assumed Regge
factorization. In contrast to DD of the transverse photons, DD of the
longitudinal photons is strongly peaked at $\beta =1$. We comment on duality
properties of DD in deep inelastic scattering.


title: Pion Wavefunctions and Truncation Sensitivity of QCD Sum Rules

abstract:
  The systematic errors inherent in the QCD sum rule approach to meson
wavefunctions are examined in the context of QCD in 1+1 spacetime dimensions in
the large N limit where the theory is exactly solvable. It is shown that the
truncation of high momentum modes induced in a lattice discretization
automatically produces a Chernyak-Zhitnitsky \cite{CZ} type meson wavefunction.
Such a truncation alters the balance of leading and higher twist terms in
correlators. We find that the reliable extraction of (a few) higher moments is
possible provided a reasonably accurate uniform approximation to the Euclidean
correlator over a suitable $Q^2$ range is available, but that the extracted
values are particularly sensitive to the balance of lower and higher twist
contributions. Underestimates of lower twist contributions or overestimates of
the highest twist term may lead to too high values for the second and fourth
moments of the pion wavefunction, suggesting a doubly peaked structure of the
Chernyak-Zhitnitsky type.


title: Negative T from a dynamical left-handed neutrino mass

abstract:
  We show how a dynamical Majorana mass for a fourth family left-handed
neutrino can make a significant negative contribution to the electroweak
correction parameter T without making a large contribution to S or U. We also
comment on other possible contributions to T in the context of dynamical
symmetry breaking.


title: Bound States of Two Gluinos at the Tevatron and LHC

abstract:
  We calculate the production cross-sections for the vector and pseudoscalar
bound states of two gluinos. It is shown that existing and future colliders
imply a realistic chance of observing gluinonium as a narrow peak in the
two-jet invariant mass spectrum. With an integrated luminosity of 0.2 fb$^{-1}$
at the Tevatron, and the high efficiency for tagging heavy quark jets at CDF,
one should be able to detect vector gluinonium for gluino masses up to about
170 GeV; or up to about 260 GeV for an upgraded Tevatron with a centre of mass
energy of 2 TeV and an integrated luminosity of 1 fb$^{-1}$. The significantly
higher energy and luminosity of LHC should allow pseudoscalar gluinonium to be
detected for gluino masses up to about 1500 GeV for an assumed luminosity of
200 fb$^{-1}$. These results are insensitive to the details of supersymmetry
models, provided that R-parity is conserved and the gluinos are lighter than
the squarks. In addition, gluinonium detection implies a relatively accurate
measure of the gluino mass, which is difficult to determine by other means.


title: Higgs Physics at LEP2

abstract:
  In this report we review the prospects for Higgs physics at LEP2. The
theoretical aspects and the phenomenology of Higgs particles are discussed
within the Standard Model (SM) and the Minimal Supersymmetric Standard Model
(MSSM). The experimental search techniques are described and the discovery
limits for Higgs bosons in the LEP2 energy range are summarized. In addition,
opportunities of detecting Higgs particles in non-minimal extensions of the SM
and the MSSM are investigated.


title: SU(3) breaking and baryon magnetic moments

abstract:
  We show that the magnetic moments of the octet baryons can be fitted to an
accuracy of 1.5 percent by a phenomenological Lagrangian in which SU(3)
breaking corrections appear only linearly. This is in contrast to conventional
chiral perturbation theory in which corrections non-analytic in SU(3) breaking
dominate and tend to spoil the agreement with the data. Motivated by this
observation, we propose a modified scheme for chiral perturbation theory that
gives rise to a similar linear breaking of SU(3) symmetry. (Pacs 13.40.Em,
14.20.-c, 11.30.Rd)


title: Shadowing Aspects of Nuclear Parton Distributions

abstract:
  Various shadowing aspects of nuclear parton distributions are discussed in a
parton-model framework. We explain existing $x$ dependent data of
$F_2^A/F_2^D$, then the model is applied to a flavor asymmetry $\bar u-\bar d$
in a nucleus, to shadowing in valence-quark distributions, and to nuclear
dependence of $Q^2$ evolution. First, we find that a finite nuclear $\bar
u-\bar d$ distribution could be possible due to nuclear interactions even in
the flavor symmetric case in the nucleon ($\bar u -\bar d$=0). Second, it is
indicated that valence-quark shadowing could be used for discriminating among
various shadowing models. Third, we find that nuclear dependence of $Q^2$
evolution $\partial [F_2^{Sn}/F_2^C]/ \partial [\ln Q^2]$, which was found by
NMC, is essentially understood by modification of parton distributions in
nuclei. However, higher-twist effects in nuclear interactions could be tested
by studying the details of the nuclear $Q^2$ evolution.


title:
$\eta \to \pi^0 \gamma \gamma$ decay in the three-flavor
  Nambu-Jona-Lasinio model

abstract:
  We study the $\eta \to \pi^0 \gamma \gamma$ decay via the quark-box diagram
in the three-flavor Nambu--Jona-Lasinio model that includes the $U_A (1)$
breaking effect. We find that the $\eta$-meson mass, the $\eta \to \gamma
\gamma$ decay width and the $\eta \to \pi^0 \gamma \gamma$ decay width are in
good agreement with the experimental values when the $U_A (1)$ breaking is
strong and the flavor $SU(3)$ singlet-octet mixing angle $\theta$ is about
zero. The photon energy and the photon invariant mass spectra in $\eta \to
\pi^0 \gamma \gamma$ are compared with those in the chiral perturbation theory.


title:
QED in Optically Active Media: Enhanced Spontaneous Emission and Chiral
  Yet Parity Conserving Corrections to the Electron Mass

abstract:
  The electromagnetic field inside an isotropic optically active medium is
quantized on the base of Fedorov's model for optical activity. The modified
photon propagator is derived. Using this result it is shown that the QED
correction to the electron mass contains chiral terms which nevertheless are
parity invariant. The spontaneous emission rate of a two-level atom is shown to
increase in the medium. The spontaneously emitted radiation is partially
polarized.


title: The Masses of the Light Quarks

abstract:
  Talk given at the Conference on Fundamental Interactions of Elementary
Particles, ITEP, Moscow, Oct. 1995. The paper reviews the current status of
knowledge concerning m_u, m_d and m_s. Qualitative aspects of the resulting
picture for the breaking of isospin and eightfold way symmetries are discussed.
At a more quantitative level, the review focuses on the chiral perturbation
theory results for the masses of the Goldstone bosons. The corresponding bounds
and estimates for the ratios m_u/m_d and m_s/m_d are described in some detail.


title:
Second order QCD corrections to the nonleptonic decay of the $b$ quark
  in the slow charm limit

abstract:
  The perturbative QCD corrections to the nonleptonic decay rate of the $b$
quark are discussed. By considering the limit where the final charmed quarks
are slow, it is argued that the coefficients of the $\alpha_s^2$ terms,
corresponding to next-to-next-to-leading order in the standard renormalization
group expansion in $\ln (m_W/m_b)$, are naturally large. The large coefficients
arise from the final-state gluon exchange between quarks and are associated
with the region of rather low momenta, which may further enhance the
phenomenological significance of these terms.


title: Data Unfolding in W mass measurements at LEP2

abstract:
  The use of an unfolding procedure is proposed as an alternative method of
extracting the $W$ boson mass from the data measured at LEP2, which may improve
the accuracy of this measurement. The benefits of the direct unfolding method
based on the Singular Value Decomposition of the response matrix are
demonstrated on the example of W mass determination from the charged lepton
energy spectra.


title: Heavy-Quark Production in $e\gamma$ Scattering

abstract:
  Open heavy flavour production at $e^+e^-$ colliders in deeply inelastic
$e\gamma$ scattering has an interesting feature: the structure function
$F_2(x,Q^2)$ for this process is calculable for $x>0.01$, and is essentially
proportional to the gluon density in the photon for smaller $x$ values. We give
estimates for event rates at LEP2 and a Next Linear Collider in $x,Q^2$ bins,
and present differential distributions in the transverse momentum and rapidity
of the heavy quark for the case of charm. We include all next-to-leading-order
QCD corrections, and find theoretical uncertainties are well under control.


title:
$\pi N \sigma$ Term , $\bar{s}s$ in Nucleon, and Scalar Form Factor ---
  a Lattice Study

abstract:
  We report on a lattice QCD calculation of the $\pi N \sigma$ term, the scalar
form factor, and $\langle N|\bar{s}s|N\rangle$. The disconnected insertion part
of $\sg$ is found to be $1.8 \pm 0.1$ times larger than the connected insertion
contribution. The $q^2$ dependence of $\sg(q^2)$ is about the same as
$G_E(q^2)$ of the proton so that $\sg(2m_{\pi}^2) - \sg(0) = 6.6 \pm 0.6$ MeV.
The ratio $y= \ss/\ud = 0.36 \pm 0.03$. Both results favor a $\sg \sim 53$ MeV,
slightly larger than our direct calculation of $\sg = 49.7 \pm 2.6$ MeV. We
also compute $F_s$ and $D_s$ and find that the agreement with those from the
octect baryon mass splittings crucially depends on the inclusion of the large
disconnected insertion. Finally, we give our result for the $K N \sigma$ term.


title: Big Bang nucleosynthesis and physics beyond the Standard Model

abstract:
  The Hubble expansion of galaxies, the $2.73\dK$ blackbody radiation
background and the cosmic abundances of the light elements argue for a hot,
dense origin of the universe --- the standard Big Bang cosmology --- and enable
its evolution to be traced back fairly reliably to the nucleosynthesis era when
the temperature was of $\Or(1)$ MeV corresponding to an expansion age of
$\Or(1)$ sec. All particles, known and hypothetical, would have been created at
higher temperatures in the early universe and analyses of their possible
effects on the abundances of the synthesized elements enable many interesting
constraints to be obtained on particle properties. These arguments have
usefully complemented laboratory experiments in guiding attempts to extend
physics beyond the Standard $SU(3)_{\c}{\otimes}SU(2)_{\L}{\otimes}U(1)_{Y}$
Model, incorporating ideas such as supersymmetry, compositeness and
unification. We first present a pedagogical account of relativistic cosmology
and primordial nucleosynthesis, discussing both theoretical and observational
aspects, and then proceed to examine such constraints in detail, in particular
those pertaining to new massless particles and massive unstable particles.
Finally, in a section aimed at particle physicists, we illustrate applications
of such constraints to models of new physics.


title: Critical Review of The Electroweak Precision Tests

abstract:
  There have been a great deal of works on the precision test of the standard
model (SM) because of the incredibly precise data obtained at the LEP and the
new measurements of $M_W$ and $m_t$ at the Fermilab Tevatron as well as the
recent theoretical progress in the higher order radiative corrections. We will
discuss some of the hidden inputs and theoretical uncertainties involved in
making the predictions of the observables in the SM. From the minimal
$\chi^2$-fit to the experimental Z-decay parameters (with the aid of a modified
ZFITTER program) in a scheme where $M_Z$, $G_{\mu}$ and $\alpha (M_Z)$ are
taken as inputs, we can predict $M_W$ for given values of $m_H$ and $m_t$. The
current world average value of $M_W$ definitely favor nonvanishing electroweak
radiative corrections and is consistent with a heavy $m_t$ as measured by the
recent CDF report but with a heavy Higgs scalar of about 500 GeV within the
context of the minimal SM. The sensitivity of and the errors in the best fit
solutions due to the uncertainties in the gluonic coupling $\alpha_s(M_Z)$ and
$\alpha (M_Z)$ are examined carefully and any trace of new physics beyond the
SM implied by the data, in a particular $R_b$ and $R_c$, is also touched upon.
In addition we discuss how the future precision measurements of $M_W$ and $Z$
decay parameters can determine the Higgs boson mass and distinguish the SM with
radiative corrections from the minimal supersymmetric standard model (MSSM) and
other extended model.


title: Perturbative corrections to zero recoil inclusive $B$ decay sum rules

abstract:
  Comparing the result of inserting a complete set of physical states in a time
ordered product of $b$ decay currents with the operator product expansion gives
a class of zero recoil sum rules. They sum over physical states with excitation
energies less than $\Delta$, where $\Delta$ is much greater than the QCD scale
and much less than the heavy charm and bottom quark masses. These sum rules
have been used to derive an upper bound on the zero recoil limit of the $B\to
D^*$ form-factor, and on the matrix element of the kinetic energy operator
between $B$ meson states. Perturbative corrections to the sum rules of order
$\alpha_s(\Delta) \Delta^2/m_{c,b}^2$ have previously been computed. We
calculate the corrections of order $\alpha_s(\Delta)$ and $\alpha_s^2(\Delta)
\beta_0$ keeping all orders in $\Delta/m_{c,b}$, and show that these
perturbative QCD corrections suppressed by powers of $\Delta/m_{c,b}$
significantly weaken the upper bound on the zero recoil $B\to D^*$ form-factor,
and also on the kinetic energy operator's matrix element.


title:
Some aspects of thermal inflation: the finite temperature potential and
  topological defects

abstract:
  Currently favoured extensions of the Standard Model typically contain `flaton
fields' defined as fields with large vacuum expectation values (vevs) and
almost flat potentials. If a flaton field is trapped at the origin in the early
universe, one expects `thermal inflation' to take place before it rolls away to
the true vacuum, because the finite-temperature correction to the potential
will hold it at the origin until the temperature falls below $1\TeV$ or so. In
the first part of the paper, that expectation is confirmed by an estimate of
the finite temperature corrections and of the tunneling rate to the true
vacuum, paying careful attention to the validity of the approximations that are
used. The second part of the paper considers topological defects which may be
produced at the end of an era of thermal inflation. If the flaton fields
associated with the era are GUT higgs fields, then its end corresponds to the
GUT phase transition. In that case monopoles (as well as GUT higgs particles)
will have to be diluted by a second era of thermal inflation. Such an era will
not affect the cosmology of GUT strings, for which the crucial parameter is the
string mass per unit length. Because of the flat Higgs potential, the GUT
symmetry breaking scale required for the strings to be a candidate for the
origin of large scale structure and the cmb anisotropy is about three times
bigger than usual, but given the uncertainties it is still compatible with the
one required by the unification of the Standard Model gauge couplings. The
cosmology of textures and of global monopoles is unaffected by the flatness of
the potential.


title: Constraints on Quartic Vector-Boson Interactions from Z Physics

abstract:
  We obtain the constraints on possible anomalous quartic vector-boson vertices
arising from the precision measurements at the $Z$ pole. In the framework of
$SU(2)_L \otimes U(1)_Y$ chiral Lagrangians, we examine all effective operators
of order $D=4$ that lead to four-gauge-boson interactions but do not induce
anomalous trilinear vertices. We constrain the anomalous quartic interactions
by evaluating their one-loop corrections to the $Z$ pole physics. Our analysis
is performed in a generic $R_\xi$ gauge and it shows that only the operators
that break the $SU(2)_C$ custodial symmetry get limits close to the theoretical
expectations. Our results also indicate that these anomalous couplings are
already out of reach of the Next Linear $e^+ e^-$ Collider, while the Large
Hadron Collider could be able to further extend the bounds on some of these
couplings.


title: Enhancement of the $\Lambda_b$ decay rate

abstract:
  The enhancement $\Delta \Gamma (\Lambda_b)$ of the $\Lambda_b$ decay rate due
to four-fermion processes of weak scattering and Pauli interference is
calculated within the quark model. An estimate of the relative $bu$ wave
function at zero separation, $|\Psi(0)|^2_{bu}$, is obtained in terms of the
$\Sigma_b^* - \Sigma_b$ hyperfine splitting, the $B^* - B$ hyperfine splitting,
and the $B$ meson decay constant $f_B$. For $M(\Sigma_b^*) - M(\Sigma_b) = 56
\pm 16$ MeV, $M(B^*) - M(B) = 46$ MeV, and $f_B = 190 \pm 40$ MeV, we find
$\Delta \Gamma(\Lambda_b) = (0.025 \pm 0.013)$ ps$^{-1}$, to be compared with
the observed enhancement $\Gamma(\Lambda_b) - \Gamma(B^0) = 0.20 \pm 0.05$
ps$^{-1}$. Even such a meager enhancement entails a value of $|\Psi(0)|^2_{bu}$
considerably larger than the corresponding value of $|\Psi(0)|^2_{cd}$ in the
$\Lambda_c$ baryon.


title:
What does a change in the quark condensate say about restoration of
  chiral symmetry in matter?

abstract:
  The contribution of nucleons to the quark condensate in nuclear matter
includes a piece of first order in $m_\pi$, arising from the contribution of
low-momentum virtual pions to the $\pi N$ sigma commutator. Chiral symmetry
requires that no term of this order appears in the $NN$ interaction. The mass
of a nucleon in matter thus cannot depend in any simple way on the quark
condensate alone. More generally, pieces of the quark condensate that arise
from low-momentum pions should not be associated with partial restoration of
chiral symmetry.


title: $Z\to b\bar b$ in $U(1)_R$ Symmetric Supersymmetry

abstract:
  We compute the one-loop corrections to the $Z \to b\bar{b}$ vertex in the
$U(1)_R$ symmetric minimal supersymmetric extension of the standard model. We
find that the predicted value of $R_b$ is consistent with experiment if the
mass of the lighter top squark is no more than 180 GeV. Furthermore, other data
combines to place a lower bound of 88 GeV on the mass of the light top squark.
A top squark in this mass range should be accessible to searches by experiments
at FNAL and LEP.


title: Particle Production and Inflaton Decay

abstract:
  A new theory of thermal history after inflation is outlined by taking into
account the effect of parametric resonance caused by inflaton oscillation. A
typical outcome is existence of a high temperature phase, that makes possible
GUT baryogenesis consistently with low enough gravitino abundance.


title: Numerical Approach to CP-Violating Dirac Equation

abstract:
  We propose a new method to evaluate the chiral charge flux, which is
converted into baryon number in the framework of the charge transport scenario
of electroweak baryogenesis. By the new method, one can calculate the flux in
the background of any type of bubble wall with any desired accuracy.


title:
SUSY model with R-parity violation, longlived charged slepton and
  quasistable matter

abstract:
  We construct SUSY $SU(3) \otimes SU(2)_{L} \otimes U(1)$ electroweak models
with superweak R-parity. The scale of R-parity violation in one of the models
is determined by the Majorana mass of neutrino and it is very small that leads
to the existence of longlived ($ T \geq O(10^{-4}sec$) lightest superparticle.
If lightest superparticle is righthanded charged slepton that can be realized
within gaugino dominated scenario then the phenomenology of such model differs
in a drastic way from the standard SUSY phenomenology, in particular, longlived
charged sleptons can form bound states with ordinary matter - quasistable
supermatter (SUSY analogs of mu-atoms and muonium). We discuss possible
manifestations of the existence of such longlived charged particle at LEP2,
TEVATRON and LHC. We also construct $SU(3) \otimes SU(2)_{L} \otimes SU(2)_{R}
\otimes U(1)$ model with Majorana mass and superweak R-parity violation.


title: Quantitative String Evolution

abstract:
  An analytic model of long string network evolution, recently developed by the
authors, is presented in detail, and modified to describe string loop
evolution. By treating the average string velocity, as well as the
characteristic lengthscale, as dynamical variables, one can include the effects
of frictional forces on the evolution of the network. This generalized
`one-scale' model provides a quantitative picture of the complete evolution of
a string network, including the prediction of previously unknown transient
scaling regimes and a detailed analysis of the evolution of the loop
population. The evolution of all cosmologically interesting string networks is
studied in detail, and possible consequences of our results are discussed.


title: Renormalization schemes and renormalons

abstract:
  We describe some ways how higher order corrections can reveal themselves if
integrated over the infrared region. We show that in different renormalization
group (RG) schemes and for some observables one has no factorial divergences.
We argue that for treating things in the infrared region it is preferable to
start with a RG scheme without the infrared Landau pole in the running coupling
constant. The uncertainties for the $\tau$ lepton width resulting from
accounting for higher order corrections are discussed.


title:
CP Nonconservation in Top Quark Production by (Un) Polarized $e^+e^-$
  and $\gamma \gamma$ Collisions

abstract:
  We report on an investigation of CP violation in (un)polarized
$e^+e^-\to{\bar t}t$ resulting from an extended neutral Higgs sector or from
the minimal SUSY extension of the Standard Model (SM). We consider c.m.
energies from the ${\bar t}t$ threshold to the TeV range. In addition
sensitivity estimates for CP-violating form factors of the top quark are made.
Further we discuss the prospects of probing Higgs sector CP violationin
$\gamma\gamma\to{\bar t}t$.


title: Meson loops in the Nambu-Jona-Lasinio model

abstract:
  The effects of meson loops in the vacuum sector of the Nambu--Jona-Lasinio
model are calculated. Using the effective action formalism we take consistently
all next-to-leading-order $1 \over \Nc$ terms into account. This leads to a
symmetry-conserving approach, in which all features of spontaneously broken
chiral symmetry, such as the Goldstone theorem, the Gold\-ber\-ger--Treiman and
the Gell-Mann--Oakes--Renner relations are preserved. Contributions to $\langle
\overline{q}q \rangle$ and $F_\pi$ are calculated, and are shown to be
substantial, at the level of $\sim 30\%$, consistent with the $1 \over \Nc$
expansion. The leading nonanalytic terms in the chiral expansion of $\langle
\overline{q}q \rangle$, $F_\pi$ and $m_\pi$ agree have the same form as the
one-loop results of chiral perturbation theory.


title: How to Run the Coupling in the Dipole Approach to the BFKL Equation

abstract:
  We use the dipole expansion to provide a systematic way of including the
running coupling into the BFKL equation. In terms of a Borel representation, we
obtain an expression for the kernel of the BFKL equation.


title: QCD Box Graphs and the Quark-Antiquark Potential

abstract:
  The $t\bar{t}$ system allows a truly perturbative treatment of the potential.
Completing previous computations, we calculate the contributions of QCD box
graph corrections, which make the ``relativistic'' $O(\a^4)$ corrections in the
non-Abelian case differ from the well known corrections of the same order in
QED.


title:
The Dipole Formalism for the Calculation of QCD Jet Cross Sections at
  Next-to-Leading Order

abstract:
  In order to make quantitative predictions for jet cross sections in
perturbative QCD, it is essential to calculate them to next-to-leading
accuracy. This has traditionally been an extremely laborious process. Using a
new formalism, imaginatively called the dipole formalism, we are able to
construct a completely general algorithm for next-to-leading order calculations
of arbitrary jet quantities in arbitrary processes. In this paper we present
the basic ideas behind the algorithm and illustrate them with a simple example.


title:
Particle-Antiparticle Asymmetry Due to Non-Renormalizable Effective
  Interactions

abstract:
  We consider a model for generating a particle-antiparticle asymmetry through
out-of-equilibrium decays of a massive particle due to non-renormalizable,
effective interactions.


title: Radiative corrections to sfermion mass splittings

abstract:
  We study the one-loop radiative corrections to the SU(2) breaking mass
splittings between sfermions in SU(2) doublets in the Minimal Supersymmetric
Standard Model. At tree-level, the differences of mass squared
$m_{\tilde{f}_{1L}}^2-m_{\tilde{f}_{2L}}^2$ of SU(2) doublet sfermions
$(\tilde{f}_1, \tilde{f}_2)_L$ in the first two generations are determined by
$\tan\beta$, and are universal to sleptons and squarks. The radiative
correction, however, breaks this relation. The typical deviation from the
universality between sleptons and squarks is within $\pm0.05$ in terms of the
``effective $\cos2\beta$''. We also study the SUSY parameter dependence of the
deviation. For very heavy sfermions, the relative corrections become large.


title: Progress in One-Loop QCD Computations

abstract:
  We review progress in calculating one-loop scattering amplitudes required for
next-to-leading-order corrections to QCD processes. The underlying technical
developments include the spinor helicity formalism, color decompositions,
supersymmetry, string theory, factorization and unitarity. We provide explicit
examples illustrating these techniques.


title: Virtual corrections to the decay $b \to s \gamma$

abstract:
  We calculate the $O(\a_s)$ virtual corrections to the matrix element for $b
\to s \gamma$, taking into account the contributions of the four-Fermi operator
$O_2$ and the electromagnetic and color dipole-type operators. The results are
combined with existing $O(\a_s)$ Bremsstrahlung corrections in order to obtain
the relevant inclusive rate. The new result drastically reduces the large scale
dependence of the leading logarithmic approximation. It implies that a very
accurate prediction for the branching ratio for $B \to X_s \g $ will become
possible once also the corrections to the Wilson coefficients are available.


title: Oscillons in a Hot Heat Bath

abstract:
  In models of real scalar fields with degenerate double-well potentials,
spherically symmetric, large amplitude fluctuations away from the vacuum are
unstable. Neglecting interactions with an external environment, the evolution
of such configurations may entail the development of an oscillon; a localized,
non-singular, time-dependent configuration which is {\it extremely} long-lived.
In the present study we investigate numerically how the coupling to a heat bath
influences the evolution of collapsing bubbles. We show that the existence and
lifetime of the oscillon stage is extremely sensitive to how strongly the field
is coupled to the heat bath. By modeling the coupling through a Markovian
Langevin equation with viscosity coefficient $\gamma$, we find that for $\gamma
\gtrsim 5 \times 10^{-4}m$, where $m$ is the typical mass scale in the model,
oscillons are not observed.

categories: hep-ph adap-org astro-ph cond-mat nlin.AO


title: Higgs Physics at $e^+e^-$ Linear Colliders

abstract:
  Prospect of Higgs physics at future $e^+e^-$ linear colliders is reviewed for
the weakly-coupled Higgs sector. Several topics related to the determination of
various couplings of the Higgs boson in the standard model as well as in the
supersymmetric standard modelare discussed.


title: The BFKL Pomeron: Can it be Detected?

abstract:
  An estimate is derived for the absolute magnitude of BFKL pomeron exchange at
$t=0$. The analysis takes account of energy conservation and of the need
realistically to model nonperturbative contributions to the BFKL integral from
infrared regions. Experiment finds that there is little or no room for a
significant BFKL term in soft processes, and this constrains its magnitude in
hard and semihard processes, so that it is unlikely to be detectable.


title: QCD: Quantum Chromodynamic Diffraction

abstract:
  The first measurements of the diffractive structure function $F_2^{D(3)}$ at
HERA are discussed. A factorisable interpretation in which a partonic structure
is assigned to the pomeron is investigated through QCD analyses in which both
the quark and gluon densities are permitted to vary freely. A method of
measuring the longitudinal structure function of the pomeron without changing
the $ep$ centre of mass energy is presented. The possibility that the pomeron
structure may receive a large contribution from gluons, relative to quarks, at
high $\beta$ is highlighted, and the experimental signatures which may support
such a structure are reviewed.


title: Theoretical issues of small $x$ physics

abstract:
  The perturbative QCD predictions concerning deep inelastic scattering at low
$x$ are summarized. The theoretical framework based on the leading log $1/x$
resummation and $k_t$ factorization theorem is described and some recent
developments concerning the BFKL equation and its generalization are discussed.
The QCD expectations concerning the small $x$ behaviour of the spin dependent
structure function $g_1(x,Q^2)$ are briefly summarized and the importance of
the double logarithmic terms which sum contributions containing the leading
powers of $\alpha_s ln^2(1/x)$ is emphasised. The role of studying final states
in deep inelastic scattering for revealing the details of the underlying
dynamics at low $x$ is pointed out and some dedicated measurements, like deep
inelastic scattering accompanied by an energetic jet, the measurement of the
transverse energy flow etc., are briefly discussed.


title:
Next-to-leading Corrections to the BFKL Equation From the Gluon and
  Quark Production

abstract:
  The gluon and quark production in the quasi-multi-Regge kinematics is
considered. The differential cross section for different helicity states is
calculated. The dimensional regularization is used to remove the infrared
divergencies in the corresponding contributions to the BFKL-equation. The other
next-to-leading corrections are discussed.


title: QCD

abstract:
  We discuss QCD studies that will be possible at LEP2. We examine both
experimental and theoretical aspects of jets, fragmentation functions,
multiplicities and particle spectra.


title: The Origin of Baryonic Matter in the Universe: A Brief Review

abstract:
  I briefly review the main ideas and challenges involved in the computation of
the observed baryonic asymmetry of the Universe.


title: The Physics of ELFE

abstract:
  This paper presents an overview of the physics program of the 15-30~GeV
continuous beam electron facility proposed by the European community of nuclear
physicists to study the quark and gluon structure of hadrons. The goal of this
new facility is to explore the quark structure of matter by exclusive and
semi-inclusive electron scattering from nuclear targets.


title: Transverse Lattice QCD in 2+1 Dimensions

abstract:
  Following a suggestion due to Bardeen and Pearson, we formulate an effective
light-front Hamiltonian for large-N gauge theory in (2+1)-dimensions. Two
space-time dimensions are continuous and the remaining space dimension is
discretised on a lattice. Eguchi-Kawai reduction to a (1+1)-dimensional theory
takes place. We investigate the string tension and glueball spectrum, comparing
with Euclidean Lattice Monte Carlo data.


title: Two-Higgs-doublet models and the Yukawa process at LEP1

abstract:
  We investigate the production of Higgs bosons $A/h$ via the Yukawa process
$Z\ra f\bar{f} \ra f\bar{f} A/h $ taking into account QCD corrections and
fermion mass effects. We estimate the discovery reach of this process and/or
bounds on the parameter space of two-Higgs doublet models which can be derived
from the analysis of $b {\bar b} \tau^+ \tau^-$ events at LEP1. These limits
have important consequences for extended models of electroweak interactions and
their experimental verification/improvement are welcome.


title:
$a_1 (1260)$ contribution to photon and dilepton productions from hot
  hadronic matter : Revisited

abstract:
  We consider the $a_{1} (1260)$ contribution to photon and dilepton
productions from hot hadronic matter. The effective lagrangian with $\pi, \rho$
and $a_{1}$ discussed by Ko and Rudaz is employed, which successfully
reproduces the $\Gamma (a_{1} \rightarrow \pi \gamma) = 670$ keV. Our results
for the photon production rate are comparable to those obtained by Xiong {\it
et al.}, while the dilepton production rates come out smaller than those
obtained by Gale {\it et al.} by an order of magnitude.


title: Neutrinos in Cosmology

abstract:
  Cosmological implications of neutrinos are reviewed. The subjects considered
involve: (a) bounds on neutrino mass from the observational limits on the
universe age and the Hubble constant both in cosmology with and without
cosmological constant; (b) distortion of spectrum of cosmic neutrinos; (c)
bounds on neutrino mass from primordial nucleosynthesis; (d) lepton asymmetry
of the universe; (e) neutrino oscillations and possible new sterile neutrinos;
(f) neutrino role in large scale structure formation.


title: Relations between the SNO and the Super Kamiokande solar neutrino rates

abstract:
  By comparing the neutrino spectra measured by SNO and Super Kamiokande, we
obtain inequalities between the ratios of observed rate to SSM rate for the two
experiments. These inequalities apply to a possibly energy-dependent reduction
of the SSM flux and to the case of neutrino oscillations. We use them to
examine the relationship between the two experiments expected for the MSW and
``Just-So" oscillation scenarios.


title: Fusion of strings and cosmic rays at ultrahigh energies

abstract:
  It is shown that the fusion of strings is a source of particle production in
nucleus--nucleus collisions outside the kinematical limits of nucleon--nucleon
collisions. This fact, together with another effect of string fusion, the
reduction of multiplicities, sheds some light on two of the main problems of
ultrahigh energy cosmic rays, the chemical composition and the energy of the
most energetic detected cosmic rays.


title: Polarized Double Photon Production in QCD to Order $\alpha_s$

abstract:
  We present a complete order $\alpha_s$ analysis of the process $p p\to \gamma
\gamma + X$ with polarized initial states, previously studied by us with
leading order structure functions. We include in our calculation new sets of
parton densities evolved in NLO QCD, such as those of Gehrmann and Stirling and
of Gl\"{u}ck et al., which incorporate the new anomalous dimensions of Mertig
and Van Neerven in the evolution equation. A detailed phenomenological analysis
is also given which includes the photon isolation. Our results indicate that
the asymmetries, although not very large, should be substantial enough at RHIC
energies to be measurable in future planned experiments.


title:
Isospin Breaking in the Nucleon Isovector Axial Charge from QCD Sum
  Rules

abstract:
  The isospin breaking in the nucleon isovector axial charge, $g_A^3$, are
calculated within the external field QCD sum-rule approach. The isospin
violations arising from the difference in up and down current quark masses and
in up and down quark condensates are included; electromagnetic effects are not
considered. We find $\delta g^3_A/g^3_A \approx (0.5-1.0)\times 10^{-2}$, where
$\delta g^3_A = (g^3_A)_p + (g^3_A)_n$ and $ g^3_A = [(g^3_A)_p -
(g^3_A)_n]/2$. Using the Goldberger-Treiman relation, we also obtain an
estimate of the isospin breaking in the pion-nucleon coupling constant,
$(g_{pp\pi_0}-g_{nn\pi_0})/g_{NN\pi} \approx (2-7) \times 10^{-3}$.


title: Electric Dipole Moment Constraints on Phases in the Constrained MSSM

abstract:
  We consider constraints on $\cp$-violating phases in the Constrained Minimal
Supersymmetric Standard Model. We find that by combining cosmological limits on
gaugino masses with experimental bounds on the neutron and electron electric
dipole moments, we can constrain the phase of the Higgs mixing mass $\mu$ to be
$|\theta_\mu| < \pi/10$, independent of choices of the other mass parameters in
the model. The other $\cp$-violating phase $\theta_A$ is essentially
unconstrained.


title: Model-independent Representation of Electroweak Data

abstract:
  General model-independent expressions are developed for the polarized and
unpolarized cross-sections for $e^+e^-\to f\bar f$ near the $Z^0$ resonance.
The expressions assume only the analyticity of S-matrix elements. Angular
dependence is included by means of a partial wave expansion. The resulting
simple forms are suitable for use in fitting data or in Monte Carlo event
generators. A distinction is made between model-independent and model-dependent
QED corrections and a simple closed expression is given for the effect of
initial-final state bremsstrahlung and virtual QED corrections.


title: The nuclear effects in $g_{1^3\rm{He}}$ and the Bjorken sum rule for A=3

abstract:
  The Bjorken sum rules for the $A=3$ and $A=1$ are used as a guide to estimate
nuclear effects in extracting $g_{1n}(x,Q^{2})$ from the
$\vec{e}\,\vec{^3\rm{He}}$ data. We estimate that the combination of the spin
depolarization, the nonnucleonic degrees of freedom in the $A=3$ system and
nuclear shadowing is likely to reduce $g_{1^3\rm{He}}(x\le 0.05)$ by $\sim 15
\%$ while a significant enhancement of the structure functions $g_{1^3\rm{He}},
g_{1^3\rm{H}}$ at $x \sim 0.1$ is predicted.


title: WTO - a deterministic approach to $4$-fermion physics

abstract:
  The program WTO, which is designed for computing cross sections and other
relevant observables in the $e^+e^-$ annihilation into four fermions, is
described. The various quantities are computed over both a completely inclusive
experimental set-up and a realistic one, i.e. with cuts on the final state
energies, final state angles, scattering angles and final state invariant
masses. Initial state QED corrections are included by means of the structure
function approach while final state QCD corrections are applicable in their
{\it naive} formulation. A gauge restoring mechanism is included according to
the Fermion-Loop scheme. The program structure is highly modular and particular
care has been devoted to computing efficiency and speed.


title:
A Democratic Seesaw Quark Mass Matrix Related to the Charged Lepton
  Masses

abstract:
  We investigate a seesaw type mass matrix $M_f\simeq m_L M_F^{-1} m_R$ for
quarks and leptons, $f$, under the assumptions that the matrices $m_L$ and
$m_R$ have common structures for the quarks and leptons, and that the matrix
$M_F$ characterizing the heavy fermion sector has the form [(unit matrix)+
(democratic-type matrix)]. We obtain well-satisfied relations for quark masses
and mixings related to the charged lepton masses.


title:
Two-Loop O(alpha_s G_F M_Q^2) Heavy-Quark Corrections to the
  Interactions between Higgs and Intermediate Bosons

abstract:
  By means of a low-energy theorem, we analyze at O(alpha_s G_F M_Q^2) the
shifts in the Standard-Model W^+W^-H and ZZH couplings induced by virtual
high-mass quarks, Q, with M_Q >> M_Z, M_H, which includes the top quark.
Invoking the improved Born approximation, we then find the corresponding
corrections to various four- and five-point Higgs-boson production and decay
processes which involve the W^+W^-H and ZZH vertices with one or both of the
gauge bosons being connected to light-fermion currents, respectively. This
includes e^+e^- -> f anti-f H via Higgs-strahlung, via W^+W^- fusion (with f =
nu_e), and via ZZ fusion (with f = e), as well as H -> 2V -> 4f (with V = W,
Z).


title: New Low-energy Leptoquark Interactions

abstract:
  We discuss an extension of the standard model (SM) with vector and scalar
leptoquarks. The renormalizable leptoquark Lagrangian consistent with the SM
gauge symmetry is presented including the leptoquark-Higgs interactions
previously not considered in the literature. We discuss the importance of these
new interactions for leptoquark phenomenology. After the electro-weak symmetry
breaking they generate non-trivial leptoquark mass matrices. These lead to
mixing between different $SU(2)_L$-multiplets of the leptoquarks and induce at
low energies new effective 4-fermion lepton-quark vertices. The latter affect
the standard leptoquark phenomenology. We discuss constraints on these
interactions from the helicity-suppressed $\pi\rightarrow \nu + e$ decay.


title: Double beta decay in left-right symmetric models

abstract:
  Left-right symmetric models provide a natural framework for neutrinoless
double beta ($\znbb$) decay. In the analysis of $\znbb$ decay in left-right
symmetric models, however, it is usually assumed that all neutrinos are light.
On the other hand, heavy {\it right-handed} neutrinos appear quite naturally in
left-right symmetric models and should therefore not be neglected. Assuming the
existence of at least one right-handed heavy neutrino, absence of $\znbb$ decay
of $^{76}$Ge currently provides the following limits on the mass and mixing
angle of right-handed W-bosons: $m_{W_R}\ge 1.1 $ TeV and $\tan(\zeta) \le 4.7
\times 10^{-3}$ for a particular value of the effective right-handed neutrino
mass, $\emnv = 1$ TeV, and in the limit of infinitly massive doubly charged
Higgs ($\Delta^{--}$). The effects of the inclusion of the Higgs triplet on
$\znbb$ decay are also discussed.


title:
The effect of random matter density perturbations on the MSW solution to
  the solar neutrino problem

abstract:
  We consider the implications of solar matter density random noise upon
resonant neutrino conversion. The evolution equation describing MSW-like
conversion is derived in the framework of the Schr\"odinger approach. We study
quantitatively their effect upon both large and small mixing angle MSW
solutions to the solar neutrino problem. This is carried out both for the
active-active $\nu_e \ra \nu_{\mu,\tau}$ as well as active-sterile $\nu_e \ra
\nu_s$ conversion channels. We find that the small mixing MSW solution is much
more stable (especially in $\Delta m^2$) than the large mixing solution. The
possible existence of solar matter density noise at the few percent level could
be tested at future solar neutrino experiments, especially Borexino.


title: Magnetic Mass in Hot Scalar Electrodynamics

abstract:
  Using the Slavnov-Taylor identities we prove that the so-called "magnetic
mass" is exactly equal to zero within hot scalar electrodynamics. The same
result is valid for hot QED and seems for any abelian theory but this is not
the case for hot QCD where one expects that $\m\ne 0$.


title: $B -> \pi l \nu$ Form Factors Calculated on the Light-Front

abstract:
  A consistent treatment of $B\rightarrow \pi l \nu$ decay is given on the
light-front. The $B$ to $\pi$ transition form factors are calculated in the
entire physical range of momentum transfer for the first time. The
valence-quark contribution is obtained using relativistic light-front wave
functions. Higher quark-antiquark Fock-state of the $B$-meson bound state is
represented effectively by the $|B^*\pi\rangle$ configuration, and its effect
is calculated in the chiral perturbation theory. Wave function renormalization
is taken into account consistently. The $|B^*\pi\rangle$ contribution dominates
near the zero-recoil point ($q^2\simeq 25$ GeV$^2$), and decreases rapidly as
the recoil momentum increases. We find that the calculated form factor
$f_+(q^2)$ follows approximately a dipole $q^2$-dependence in the entire range
of momentum transfer.


title:
Proton lifetime, Yukawa couplings and dynamical SUSY breaking in SU(5)
  GUT

abstract:
  We study the influence of messenger Yukawa couplings and top, bottom and
$\tau$ Yukawa couplings on the proton lifetime in SU(5) Supersymmetric GUT with
dynamical supersymmetry breaking mechanism due to Dine and Nelson.


title: Screening in High-T QCD

abstract:
  These days, as high energy particle colliders become unavailable for testing
speculative theoretical ideas, physicists are looking to other environments
that may provide extreme conditions where theory confronts physical reality.
One such circumstance may arise at high temperature $T$, which perhaps can be
attained in heavy ion collisions or in astrophysical settings. It is natural
therefore to examine the high-temperature behavior of the standard model, and
here I shall report on recent progress in constructing the high-$T$ limit
of~QCD.


title: Baryon masses in a chiral expansion with meson-baryon form factors

abstract:
  The chiral expansion of the one-loop corrections to baryon masses is examined
in a generic meson-cloud model with meson-baryon form factors. For pion loops,
the expansion is rapidly convergent and at fourth order in $m_\pi$ accurately
reproduces the full integral. In contrast, the expansion is found to converge
very slowly for kaon loops, raising questions about the usefulness of chiral
expansions for kaon-baryon physics. Despite the importance of high-order terms,
relations like that of Gell-Mann and Okubo are well satisfied by the baryon
masses calculated with the full integral. The pion cloud cloud makes a
significant contribution to the $\pi N$ sigma commutator, while kaon cloud
gives a very small strangeness content in the nucleon.


title: A Surprise in Sum Rules - Modulating Factors

abstract:
  A generic physical situation is considered where Im $\Pi$, the imaginary part
of polarization operator (generalized susceptibility), can be measured on a
finite interval and the high frequency asymptotics (up to a few orders) of
$\Pi$ can be calculated theoretically. In such a case, it is desirable to
derive an equivalent form of the Kramers-Kronig dispersion relation, the
so-called sum rule, in which both the high-frequency part of Im $\Pi$ in the
dispersion integral and the high-order contribution to $\Pi$ are suppressed. We
provide a general framework for derivation of such sum rules, without any
recourse to an infinite-order differential operator. We derive sum rules for a
wide set of weight functions and show that any departure from the $e^{-t}$
behaviour of the weight function in sum rules leads to modulating factors on
the theoretical side of sum rules, providing its low frequency regularization.
We argue that by including modulating factors one can extend the domain of
validity of sum rules further to an intermediate region of frequencies and can
account for ``bumps" which were observed numerically on the phenomenological
side of sum rules at ``intermediate'' frequencies.


title: Hadrons and QCD Instantons: a Bosonized View

abstract:
  In a dilute system of instantons and antiinstantons, the U$_{\rm A}$(1) and
scale anomalies are shown to be directly related to the bulk susceptibility and
compressibility of the system. Using $1/N_c$ (where $N_c$ is the number of
colors) as a book-keeping argument, mesonic, baryonic and gluonic correlators
are worked out in p-space and Fourier transformed to x-space for a comparison
with recently simulated correlators. The results are in overall agreement with
simulations and lattice calculations, for distances up to 1.5 fm, despite the
fact that some channels lack the necessary physical singularities. We analyze
various space-like form factors of the nucleon and show that they are amenable
to constituent quark form factors to leading order in $1/N_c$. Issues related
to the lack of confinement in the model and its consequence on the various
correlation functions and form factors are also discussed.


title: Quantum Gravity Slows Inflation

abstract:
  We consider the quantum gravitational back-reaction on an initially
inflating, homogeneous and isotropic universe whose topology is $T^3 \times
\Re$. Although there is no secular effect at one loop, an explicit calculation
shows that two-loop processes act to slow the rate of expansion by an amount
which becomes non-perturbatively large at late times. By exploiting Feynman's
tree theorem we show that all higher loops act in the same sense.


title: The Quantum Gravitational Back-Reaction On Inflation

abstract:
  We describe our recent calculation of two-loop corrections to the expansion
rate of an initially inflating universe on the manifold $T^3 \times \Re$. If
correct, our result proves that quantum gravitational effects slow the rate of
inflation by an amount which becomes non-perturbatively large at late times. In
a preliminary discussion of basic issues we show that the expansion rate is a
gauge invariant, and that our ultraviolet regulator does not introduce spurious
time dependence. We also derive a sharp bound on the maximum strength of higher
loop effects.


title: One Loop Graviton Self-Energy In A Locally De Sitter Background

abstract:
  The graviton tadpole has recently been computed at two loops in a locally de
Sitter background. We apply intermediate results of this work to exhibit the
graviton self-energy at one loop. This quantity is interesting both to check
the accuracy of the first calculation and to understand the relaxation effect
it reveals. In the former context we show that the self-energy obeys the
appropriate Ward identity. We also show that its flat space limit agrees with
the flat space result obtained by Capper in what should be the same gauge.


title: The decay $h^0 \to A^0A^0$: a complete 1-loop calculation in the MSSM

abstract:
  In the minimal supersymmetric standard model the decay $h^0 \to A^0A^0$ of
the light neutral scalar $h^0$ is kinematically allowed for low values of
$\tan\beta$ when radiative corrections to the neutral Higgs masses are taken
into account. The width of this decay mode is revisited on the basis of a
complete 1-loop diagrammatic calculation. We give the analytical expressions
and numerical results and compare them with the corresponding ones from the
simpler and compact approximations of the effective potential method and the
renormalization group approach.


title:
Delta s density in a proton and unpolarized lepton - polarized proton
  scatterings

abstract:
  It is shown that the parity--violating deep--inelastic scatterings of
unpolarized charged leptons on polarized protons, $\ell^{\mp} + \vec P\to
\stackrel{\scriptscriptstyle(-)}{\nu_{\ell}} + X$, could provide a sensitive
test for the behavior and magnitude of the polarized strange--quark density in
a proton. Below charm threshold these processes are also helpful to uniquely
determine the magnitude of individual polarized parton distributions.


title: Constraints on gluon evolution at small x

abstract:
  The BFKL and the unified angular-ordered equations are solved to determine
the gluon distribution at small $x$. The impact of kinematic constraints is
investigated. Predictions are made for observables sensitive to the gluon at
small $x$. In particular comparison is made with measurements at the HERA
electron-proton collider of the proton structure function $F_2 (x, Q^2)$ as a
function of $\ln Q^2$, the charm component, $F_2^c(x,Q^2)$ and diffractive
$J/\psi$ photoproduction.


title: Hard diffractive electroproduction of heavy flavor vector mesons in QCD

abstract:
  We outline $QCD$ predictions for the diffractive electroproduction of heavy
flavor vector mesons and compare them with available data.


title:
Long distance contribution to $K^+ \to \pi^+ \nu {\bar \nu}$ decay and
  $O(p^4)$ terms in CHPT

abstract:
  The long distance contribution to $K^+ \to \pi^+ \nu {\bar \nu} $ is
calculated using chiral perturbation theory. The leading contribution comes
from $O(p^4)$ tree terms. The branching ratio of the $O(p^4)$ long distance
contribution is found to be of order $10_{-3}$ smaller than the short distance
contributions.


title:
The $\rho$ Meson Light-Cone Distribution Amplitudes of Leading Twist
  Revisited

abstract:
  We give a complete re-analysis of the leading twist quark-antiquark
light-cone distribution amplitudes of longitudinal and transverse $\rho$
mesons. We derive Wandzura-Wilczek type relations between different
distributions and update the coefficients in their conformal expansion using
QCD sum rules including next-to-leading order radiative corrections. We find
that the distribution amplitudes of quarks inside longitudinally and
transversely polarized $\rho$ mesons have a similar shape, which is in
contradiction to previous analyses.


title: On the Problem of Boosting Nonleptonic b Baryon Decays

abstract:
  The constituent picture of hadrons implies certain quantum mechanical
inequalities which must hold in the potential models. Basing on this
qualitative consideration I argue that it is not easy to increase significantly
the scale of the flavor-dependent 1/m_b^3 effects within the heavy quark
expansion preserving the conventional constituent picture of heavy flavor
hadrons. I briefly address the physical consequences one might expect if the
effects of weak scattering and interference are attempted to be pushed above
the 10% level within 1/m_b expansion not invoking qualitatively different
mechanisms including violations of duality.


title: Fermion Masses and Mixing in SUSY GUT

abstract:
  The problem of fermion masses and mixings is discussed in the context of
supersymmetric grand unification theories. Some predictive frameworks based on
the $SU(5)$, $SO(10)$ and $SU(6)$ models are reviewed. [Based on lectures
delivered at the ICTP Summer School on `High Energy Physics and Cosmology',
Trieste, Italy, 3-28 July 1995 (to appear on Proceedings), and XIX Int.
Conference on {\em Particle Physics and Astrophysics in the Standard Model and
Beyond}, Bystra, Poland, 19-26 September 1995]


title: Astrophysical Implications of the Mirror World with Broken Mirror Parity

abstract:
  We discuss the physics of the mirror (shadow) world which is completely
analogous to the visible one except that its `weak' scale is larger by one or
two orders of magnitude than the weak scale in the standard model. The mirror
neutrinos can mix the ordinary ones through the Planck scale induced higher
order operators, which can help to reconcile the present neutrino puzzles that
are the solar and atmospheric neutrino deficits, the recent LSND anomaly and
the need in the $\sim$ eV mass neutrino as the hot dark matter. In particular,
oscillation of $\nu_e$ into its mirror partner $\nu'_e$ emerges with parameters
naturally in the MSW range. The nucleosynthesis constraint on the extra light
particle species can be fulfilled by assuming the asymmetric postinflationary
reheating between the usual and mirror worlds. One implication of our proposal
is that bulk of the dark matter in the universe may be a warm dark matter
consisting of the keV range mirror neutrinos rather than the conventional cold
dark matter, while the mirror baryons can also contribute as dissipative dark
matter. Implications of the mirror Machos for microlensing experiments are also
discussed. [Talk given at the XIX int. conference on `Particle Physics and
Astrophysics in the Standard Model and Beyond', Bystra, Poland, 19-26 September
1995 (to appear on Proceedings). Based on refs. \cite{BM,BDM} done in
collaboration with A.D. Dolgov and R.N. Mohapatra]


title: Z' Reservation at LC2000

abstract:
  We consider the possibility that one extra $Z\equiv Z'$ exists with a mass of
more then two TeV and fermion couplings that do not violate (charged) lepton
universality. We show that, in such a situation, a functional relationship is
generated between the \underline{deviations} from the SM values of three
leptonic observables of two-fermion production at LC 2000 that is completely
independent of the values of the $Z'$ mass and couplings. This selects a
certain region in the 3-d space of the deviations ($Z'$ "reservation") that is
\underline{characteristic} of the model and that would have no observable
intersection with analogous regions corresponding to other interesting models
of new physics.