title:
How fast can the wall move? A study of the electroweak phase transition
  dynamics

abstract:
  We consider the dynamics of bubble growth in the Minimal Standard Model at
the electroweak phase transition and determine the shape and the velocity of
the phase boundary, or bubble wall. We show that in the semi-classical
approximation the friction on the wall arises from the deviation of massive
particle populations from thermal equilibrium. We treat these with Boltzmann
equations in a fluid approximation. This approximation is reasonable for the
top quarks and the light species while it underestimates the friction from the
infrared $W$ bosons and Higgs particles. We use the two-loop finite temperature
effective potential and find a subsonic bubble wall for the whole range of
Higgs masses $0<m_H<90$GeV. The result is weakly dependent on $m_H$: the wall
velocity $v_w$ falls in the range $0.36<v_w<0.44$, while the wall thickness is
in the range $29> L T > 23 $. The wall is thicker than the phase equilibrium
value because out of equilibrium particles exert more friction on the back than
on the base of a moving wall. We also consider the effect of an infrared gauge
condensate which may exist in the symmetric phase; modelling it simplemindedly,
we find that the wall may become supersonic, but not ultrarelativistic.


title:
Decay Constants and Semileptonic Decays of Heavy Mesons in Relativistic
  Quark Model

abstract:
  We investigate the $B$ and $D$ mesons in the relativistic quark model by
applying the variational method with the Gaussian wave function. We calculate
the Fermi momentum parameter $p_{_F}$, and obtain $p_{_F} = 0.50 \sim 0.54$
GeV, which is almost independent of the input parameters, $\alpha_s$, $m_b$,
$m_c$ and $m_{sp}$. We then calculate the ratio $f_B$/$f_D$, and obtain the
result which is larger, by the factor of about 1.3, than $\sqrt{M_D / M_B}$
given by the naive nonrelativistic analogy. This result is in a good agreement
with the recent Lattice calculations. We also calculate the ratio
$(M_{B^*}-M_{B})$/$(M_{D^*}-M_{D})$. In these calculations the wave function at
origin $\psi (0)$ is essential. We also determine $p_{_F}$ by comparing the
theoretical prediction of the ACCMM model with the lepton energy spectrum of $B
\rightarrow e \nu X$ from the recent ARGUS analysis, and find that
$p_{_F}=0.27~\pm~^{0.22}_{0.27}$ GeV, when we use $m_c=1.5$ GeV. However, this
experimentally determined value of $p_{_F}$ is strongly dependent on the value
of input parameter $m_c$.


title: Electroweak Baryogenesis in Supersymmetric Models

abstract:
  The baryon density which may be produced during the electroweak phase
transition in supersymmetric models is computed, taking into account the
previously neglected effects of transport, strong and weak anomalous fermion
number violation, thermal scattering, and a new method for computing \cp\
violating processes during the transition. We can account for the observed
baryon asymmetry, provided new \cp-violating phases are greater than $\sim
10^{-(2-4)}$, and some superpartners are light enough to be relevant during the
transition, which takes place at a temperature of (50-100) GeV. In one case,
light superpartners are the top squarks and the charginos and/or the
neutralinos; in another case the top squarks and both Higgs doublets are light.
Our calculation is easily extended to the case of a general two Higgs model,
where we find sufficient baryogenesis provided that a certain combination of
parameters in the Higgs potential leads to a \cp\ violating space dependent
phase in the top quark mass of order $ 10^{-3}$.


title: The Sphaleron Rate in the "Symmetric" Electroweak Phase

abstract:
  I calculate the rate of $B+L$ violating processes in the ``symmetric" phase
of the Standard Model by means of semiclassical methods, which are based on an
appropriately resummed loop expansion within the dimensionally reduced theory.
The rate is found to reach its asymptotic form $\Gamma/V=c(\a_W T)^4$ at a
temperature about three times the critical temperature of the electroweak phase
transition, with a coefficient $c\sim 0.01$ at the one-loop level. The order of
magnitude of $c$ is sensitive to higher order corrections to the dynamically
generated vector boson mass if these are greater than 20\%. The temperature
below which baryon number dissipation is in thermal equilibrium in the early
universe is estimated to be $T_*\sim 10^{11} {\rm GeV}$.


title: Reaction \gamma \pi \to \pi \pi in a confined quark model

abstract:
  A confined quark model study in a couple of chirally anomalous processes is
presented in comparison with effective meson Lagrangian approaches of various
kind. The processes considered are \pi^0 \to \gamma \gamma and \gamma \to \pi^+
\pi^- \pi^0 (or the equivalent \pi \gamma \to \pi\pi) for which there is a
well-known low energy theorem relating the latter amplitude with the former one
by a very simple algebraic relation in the zero energy (or chiral, or soft
pion) limit. Our quark model naturally generates the so-called contact term in
the amplitude for the second process, but with the opposite sign to what
effective chiral meson models indicate. A reinterpretation of our vector pole
contribution restores the consistency, however. While the first reaction is
observed to serve in it calibrating various models, it is found difficult,
based upon the quality of the existing data in the second reaction, to single
out the best model, which appears indispensable for testing the validity of the
above low energy theorem. Thus the proposed experiments and their analyses
should aim at attaining an optimal accuracy.


title:
Radiative Corrections to the Z-b-(anti-b) and Z-tau-(anti-tau) Vertices
  in a Realistic One-Family Extended Technicolor Model

abstract:
  In a realistic effective one-family extended technicolor(ETC) model without
exact custodial symmetry, we calculate the one-loop corrections to the
Z-b-(anti-b) and Z-tau-(anti-tau)vertices from the sideways and diagonal ETC
bosons exchange. The result shows that both the Z-->b+anti-b partial width (and
the branching ratio) and the tau polarization asymmetry parameter A_tau are
enhanced by the corrections and are in agreement with the present experimental
data.


title: Are oscillons present during a first order electroweak phase transition?

abstract:
  It has been recently argued that localized, unstable, but extremely
long-lived configurations, called oscillons, could affect the dynamics of a
first order electroweak phase transition in an appreciable way. Treating the
amplitude and the size of subcritical bubbles as statistical degrees of
freedom, we show that thermal fluctuations are not strong enough to generate
subcritical configurations able to settle into a an oscillon long-lived regime.


title: Interpolating fields for spin-1 mesons

abstract:
  Three commonly used types of effective theories for vector mesons are shown
to correspond to different choices of interpolating field for spin-1 particles
and the rules for transforming between them are described. The choice of fields
that transform homogeneously under the nonlinear realisation of chiral symmetry
imposes no preconceptions about the types of coupling for the mesons, and so
this representation is particularly useful for comparing different theories. By
converting them into this form, hidden-gauge theories are shown to contain an
adjustable parameter, the gauge coupling. The normal choice for this is seen to
be one that reduces the momentum dependence of the effective $\rho\pi\pi$
coupling, explaining the success of the ``low-energy theorem" of that approach.


title: Leading/nonleading Charm Hadroproduction in the Quark-Gluon String Model

abstract:
  Leading charm production in reaction $\pi^- N \rightarrow DX$ is
discussed.Three experiments at Fermilab and CERN have measured a rather large
enhancement in production rate of leading $D^-$-mesons over nonleading $D^+$.A
good description of these results is obtained in Quark Gluon String Model
(QGSM) if the idea of 'intrinsic charm' is involved. The weight of the
$c\bar{c}$ pairs in the quark sea of colliding hadrons is estimated from the
experimental data. The comparison with other theoretical models is also carried
out.


title:
Luminosities for Vector-Boson Vector-Boson Scattering at High Energy
  Colliders

abstract:
  We derive exact expressions for luminosities of massive vector-boson pairs
which can be used to describe the cross sections for processes in hadron
collisions or $e^+e^-$ annihilation which proceed via two-vector-boson
scattering. Our approach correctly takes into account the mutual influence of
the emission of one vector boson on the emission of a second one. We show that
only approximately the exact luminosities can be factorized into convolutions
of single-vector-boson distributions. Numerical results are given and compared
to simplified approaches.


title: QCD Analysis of Diffractive DIS at HERA

abstract:
  The QCD analysis of deep inelastic diffractive scattering at HERA is
performed assuming the dominance of the "soft" pomeron exchange and simple,
physically motivated parametrization of parton distributions in the pomeron.
  Both the LO and NLO approximations are considered and the theoretical
predictions concerning the quantity $R=F_L^D/F_T^D$ for diffractive structure
functions are presented.


title: On the Stability of Quark Solitons in QCD

abstract:
  We critically re-examine our earlier derivation of the effective low energy
action for QCD in 4 dimensions with chiral fields transforming non-trivially
under both color and flavor, using the method of anomaly integration. We find
several changes with respect to our previous results, leading to much more
compact expressions, and making it easier to compare with results of other
approaches to the same problem. With the amended effective action, we find that
there are no stable soliton solutions. In the context of the quark soliton
program, we interpret this as an indication that the full low-energy effective
action must include additional terms, reflecting possible modifications at
short distances and/or the non-trivial structure of the gauge fields in the
vacuum, such as $ <F_{\mu\nu}^2> \neq 0$. Such terms are absent in the
formalism based on anomaly integration.


title: A Finite Group Analysis of the Quark Mass Matrices and Flavor Dynamics

abstract:
  We perform a finite group analysis on the quark mass matrices. We argue that
the dominant terms should be proportional to class operators of the group and
that symmetry breaking to split the mass spectrum and simultaneous
diagonalizability to suppress flavor changing neutral currents can be
accomplished at this point. The natural setting is a multi-scalar model and the
scalar doublets can have masses of the weak scale without any parameter tuning.
When we specialize to $S_3$ as the group of choice, we arrive at the results
that the dominant mass terms are $\lhook $democratic$\rhook $ and that the
ratios of light masses and the Cabbibo angle $\cong ({m_d\over m_s})^{1\over
2}$ are all given by group parameters in the breaking of $S_3$ to $S_2$. A
large mass expansion is then performed and a generalized Wolfenstein
parameterization is given. Further breaking by way of introducing heavy-light
transitions in the down-type mass matrix is here related to the heavy-light
Cabbibo-Kobayashi-Maskawa elements.


title: Direct and resolved pomeron

abstract:
  We investigate the effect of a direct pomeron coupling to quarks in DIS and
photoproduction of jets. The direct pomeron coupling generates a point-like
contribution to the diffractive part of the structure function $F_2$, which is
analysed on the basis of the latest H1 data. Our model assumptions for the
pomeron structure are consistent with the measured data.


title: Correlated Neutrino Oscillations

abstract:
  In solar neutrino oscillations, if $\nu_e$ has a significant third massive
component, the allowed parameter space in $\Delta m^2$ and $\sin^2 2 \theta$
for the first two components is shown to be greatly increased. This third
component may be correlated to atmospheric neutrino oscillations, as shown in a
specific predictive seesaw model of the $3 \times 3$ neutrino mass matrix.
Possible variations to include the recent LSND results are briefly discussed.


title:
Totally Chaotic Poissonian-Like Sources in Multiparticle Production
  Processes?

abstract:
  In all multiparticle processes the concept of sources directly emitting
finally observed secondaries (mostly pions) plays crucial role. Here we shall
present them from yet another point of view in which elementary sources
composing all processes (from e+e- annihilation, via pp up to AA interactions)
remain both totally 'chaotic' and Poissonian at the same time.


title: Scheme Dependence at Small x

abstract:
  We discuss the evolution of F_2^p at small x, emphasizing the uncertainties
related to expansion, fitting, renormalization and factorization scheme
dependence. We find that perturbative extrapolation from the measured region
down to smaller x and lower Q^2 may become strongly scheme dependent.


title:
Accelerator, reactor, solar and atmospheric neutrino oscillation: beyond
  three generations

abstract:
  We perform a phenomenological analysis of neutrino oscillation in a four
generation framework introducing an additional sterile neutrino. In such a
scenario, more than one pattern is possible that can accommodate three
hieararchically different mass squared differences as required by the present
experiments. We considered two different spectrums. Choosing the
${\Delta{m}}^2$s in the ranges suitable for the LSND, atmospheric and solar
neutrino oscillation, limits on the mixing angles are derived, consistent with
the most restrictive accelerator and reactor data as well as the atmospheric
and solar neutrino results. The allowed mixing angles are found to be
constrained very severely in both cases. For one mass pattern in the combined
allowed zone the atmospheric anomaly can be explained by $\nu_e - \nu_{\mu}$
oscillation whereas for the other the $\nu_{\mu} - \nu_{\tau}$ channel is
preferred. The accelerator experiments CHORUS and NOMAD have different
sensitivities in these regions and they can distinguish between the two
choices.


title: QCD corrections to charged Higgs-mediated $b \to c \tau \nu$ decay

abstract:
  We calculate the $O(\alpha_s)$ corrections to the charged Higgs mediated
inclusive semi-tauonic $B$ decay. By working in the Landau gauge, we
demonstrate how to obtain the charged Higgs contributions (both direct and
interference terms) from the known QCD corrections to $t \to b H^+$. Combining
our results with $O(1/m_b^2)$ corrections to the spectator model and comparing
the theoretical prediction with the recent experimental measurements, we find a
model-independent $2\sigma$ upper bound on the ratio of Higgs vacuum
expectation values, $\tan\beta<0.52(m_H/1 GeV)$.


title: Strings and Supersymmetry as Tools for Perturbative QCD

abstract:
  We review techniques simplifying the analytic calculation of one-loop QCD
amplitudes with many external legs, for use in next-to-leading-order
corrections to multi-jet processes. We explain how a supersymmetry-inspired
organization works well in conjunction with other tools, namely the color and
helicity decompositions of amplitudes, and the constraints imposed by
perturbative unitarity and collinear singularities. String theory seems most
useful as a heuristic guide. Using these techniques, the complete set of
one-loop five-parton QCD amplitudes, as well as certain sequences of special
helicity amplitudes with an arbitrary number of external gluons, have been
obtained.


title: Prospects for mass unification at low energy scales

abstract:
  A simple Pati-Salam SU(4) model with a low symmetry breaking scale of about
1000 TeV is presented. The analysis concentrates on calculating radiative
corrections to tree-level mass relations for third generation fermions. The
tree-level relation $m_b/m_{\tau}=1$ predicted by such models can receive large
radiative corrections up to about $50\%$ due to threshold effects at the mass
unification scale. These corrections are thus of about the same importance as
those that give rise to renormalisation group running. The high figure of
$50\%$ can be achieved because 1-loop graphs involving the physical charged
Higgs boson give corrections to $m_{\tau}-m_b$ that are proportional to the
large top quark mass. These corrections can either increase or decrease
$m_b/m_{\tau}$ depending on the value of an unknown parameter. They can also be
made to vanish through a fine-tuning. A related model of tree-level
$t$-$b$-$\tau$ unification which uses the identification of SU(2)$_R$ with
custodial SU(2) is then discussed. A curious relation $m_b \simeq \sqrt{2}
m_{\tau}$ is found to be satisfied at tree-level in this model. The overall
conclusion of this work is that the tree-level relation $m_b = m_{\tau}$ at low
scales such as 1000 TeV or somewhat higher can produce a successful value for
$m_b/m_{\tau}$ after corrections, but one must be mindful that radiative
corrections beyond those incorporated through the renormalisation group can be
very important. This motivates that an on-going search for the rare decays
$K^0_L \to \mu^{\pm} e^{\mp}$ be maintained.


title: Stable Calculations for Unstable Particles: Restoring Gauge Invariance

abstract:
  We discuss theoretical and phenomenological aspects of the use of boson
propagators with energy-dependent widths in predictions for high-energy
scattering processes. In general, gauge invariance is violated in such
calculations. We discuss several approaches to restore gauge invariance,
necessary for a reliable result. The most promising method is the addition of
the relevant parts of the fermionic corrections, which fulfills all Ward
identities. The numerical difference between this and other approaches is
studied. A number of recommendations are given for LEP2 computations.


title:
Charm Photoproduction At Large Transverse Momentum And The Charm Content
  Of The Photon

abstract:
  The charm quark photoproduction at large transverse momentum in the resolved
photon interaction via partonic subprocess $\cg$ is studied. It is shown that
at HERA energies the contribution of the charm quark excitation in the photon
in the inclusive charm production at $\pt>5$ GeV/c dominates over the other
resolved photon contribution via the gluon content of the photon and it is
about 30\% of the contribution of the $c\bar c$-pair production via the
photon-gluon fusion mechanism.


title: The Nucleon's Virtual Meson Cloud and Deep Inelastic Lepton Scattering

abstract:
  We address the question whether the nucleon's antiquark sea can be attributed
entirely to its virtual meson cloud and, in essence, whether there exists a
smooth transition between hadronic and quark-gluon degrees of freedom. We take
into account contributions from $\pi$ and $K$ mesons and compare with the
nucleon's antiquark distributions which serve as a non-perturbative input to
the QCD evolution equations. We elucidate the different behavior in the flavor
singlet and non-singlet channels and study the dependence of our results on the
scale $Q^2$. The meson-nucleon cut-offs that we determine give not only an
indication on the size of the region within which quarks are confined in a
nucleon, but we find that the scale of these form factors is closely related to
the four-momentum transfer, $Q^2$, where gluons are resolved by a high energy
probe, and that large meson loop momenta, $|{\bf k}| \approx 0.8$ GeV,
contribute significantly to the sea quark distributions. While the agreement of
our calculations with data-based parametrizations is satisfactory and scale
independent for the flavor breaking share of the nucleon's antiquark sea, the
flavor singlet component is quite poorly described. This hints the importance
of gluon degrees of freedom.


title: Stringy Unification Helps See-Saw Mechanism

abstract:
  In this paper we explore the possibility of intermediate scale physics in the
context of superstring models with {\it higher Kac-Moody levels}, by focusing
on left-right and Pati-Salam symmetries. We find that the left-right scale may
lie in the range $10^{10} - 10^{12}$ GeV which is favored by neutrino physics,
while the Pati-Salam scale is at most two or three orders of magnitude below
the unification scale $M_X$. We also show that the scale of $B-L$ breaking can
be as low as 1 TeV or so, providing protection against too rapid proton decay
in supersymmetry. Our results allow a natural value for the scale $M_X \sim
10^{18}$ GeV and the agreement with the experiment requires the value of
$\sin^2 {\theta_w}$ at $M_X$ to be in general very different from the usually
assumed $3/8$.


title: Fragmentation production of doubly heavy baryons

abstract:
  Baryons with a single heavy quark are being studied experimentally at
present. Baryons with two units of heavy flavor will be abundantly produced not
only at future colliders, but also at existing facilities. In this paper we
study the production via heavy quark fragmentation of baryons containing two
heavy quarks at the Tevatron, the LHC, HERA, and the NLC. The production rate
is woefully small at HERA and at the NLC, but significant at $pp$ and
$p\bar{p}$ machines. We present distributions in various kinematical variables
in addition to the integrated cross sections at hadron colliders.


title:
Searching for An Intermediate-Mass Higgs and New Physics in Two-Photon
  Coherent Processes at the LHC

abstract:
  We reexamine the prospects for searching for a neutral Higgs boson in the
intermediate-mass range and physics beyond the standard model, using the
proton- and ion-beam facilities of the LHC to study coherent two-photon
processes. Considering realistic design luminosities for the different ion
beams, we find that beams of light-to-medium size ions like calcium will give
the highest production rates. With a suitable trigger and assuming a b-quark
identification efficiency of $30\%$ and a $b{\bar b}$ mass resolution of 10 GeV
one could expect to see a Higgs signal in the $b{\bar b}$ channel with a 3-4
$\sigma$ statistical significance in the first phase of operation of the LHC
with beams of calcium. The discovery potential for light supersymmetric
particles is as promissing. The study of such very ``quiet'' final state
topologies in heavy ion collisions could even lead to the discovery of a new
phase of QED.


title:
Longitudinal Contribution to the Alignment Polarization of Quarks
  Produced in e+ e- Annihilation: An O(alpha_s) Effect

abstract:
  We calculate the longitudinal contribution to the alignment polarization
$\Pl$ of quarks produced in $e^+e^-$ annihilation. In the Standard Model, the
longitudinal alignment polarization vanishes at the Born term level and thus
receives its first non-zero contribution from the $O(\as)$ tree graph process.
We provide analytical and numerical results for the longitudinal alignment
polarization of massless and massive quarks, in particular for the recently
discovered top quark.


title: Baby Skyrmion Strings

abstract:
  We provide analytical and numerical evidence of the existence of classically
stable, string-like configurations in a 2+1 dimensional analog of the Skyrme
model. The model contains a conserved topological charge usually called the
baryon number. Our strings are non-topological solitons which have a constant
baryon number per unit length. The energy per length containing one baryon is,
however, less than the energy of an isolated baryon (radially symmetric ``baby
Skyrmion") in a region of the parameter space, which suggests a degree of
stability for our configurations. In a limiting case, our configuration
saturates a Bogomolnyi-type bound and is degenerate in energy per baryon with
the baby Skyrmion. In another limiting case, the energies are still degenerate
but do not saturate the corresponding Bogomolnyi-type bound. Nonetheless, we
expect the string to be stable here. Both limiting cases are solvable
analytically.


title: Modified renormalon

abstract:
  In the framework of renormalon consideration in the approximation of a large
number of quark flavours, a role of the anomalous dependence of gluon
propagator on the scale $\mu$ is shown.


title:
Time reversal violation in $K^+ \to \mu^+ \nu \gamma$ decay and three
  Higgs model

abstract:
  Transverse muon polarization in the $K^+ \rightarrow \mu^+ \nu \gamma$ decay
is calculated in the model with scalar and pseudo scalar four-Fermi
interactions. Combined with a similar calculation in the $K^+ \rightarrow \mu^+
\nu \pi^0$ decay, a possible constraint on parameters in the three-Higgs model
is obtained assuming sensitivity of the up-coming KEK experiment. It is pointed
out that the predictions for the two polarizations are strongly correlated in
the three Higgs model.


title:
Some Remarks on Nu(mu)-Nu(e) Oscillations of Terrestrial Neutrinos and
  Atmospheric Neutrino Oscillations

abstract:
  We present the results of an analysis of the data of reactor and accelerator
neutrino oscillation experiments in the framework of a model with mixing of
three massive neutrino fields and a neutrino mass hierarchy. The results of the
LSND experiment are commented. Taking into account future long-baseline
neutrino oscillation experiments, we have also analyzed the atmospheric
neutrino data in the framework of the model.


title: R-parity breaking phase transition in the susy singlet majoron model

abstract:
  We consider thermal properties of the susy singlet majoron model. We compute
the critical temperature $T_c$ and the subsequent reheating temperature $T_{\rm
RH}$ for $R$-parity breaking. Succesful baryogenesis constrains the parameter
space via the requirements that $T_c$ and $T_{\rm RH}$ are lower than the
electroweak phase transition temperature. A further constraint is provided by
requiring that the gauge singlet should be kinematically allowed to decay, in
order not to have a matter dominated universe at the time of nucleosynthesis.
We have made a detailed study of the parameter space and find an upper limit
for the susy breaking scalar mass $\mm\lsim 750~(900)$ GeV if
$\gluino=100~(1000)$ GeV, which is valid except for certain special values of
the singlet sector parameters.


title: Hard-soft factorization in B_c--> psi pi decay

abstract:
  The width of $B_c^+\to \psi \pi^+$ decay is calculated in the framework of
factorization of a hard gluon exchange and a soft binding of quarks in the
heavy quarkonium, so that ${\rm BR}(B_c^+\to \psi \pi^+) = 2.0\pm 0.5$ \%.


title: Extended Electroweak Models and Their Tests in Future Colliders

abstract:
  Some possible tests of physics beyond the Standard Model in the next
generation collider experiments are considered. The main emphasis is put on the
processes which may be studied in the non-conventional $e^-e^-$, $e^-\gamma$
and $\gamma\gamma$ operation modes of the next linear collider (NLC). In
particular, sensitivity of the NLC for testing the gauge boson
self-interactions through the reaction $e^-\gamma\to W^-\nu$ is investigated.
High energy tests of the susy and non-susy left-right symmetric models are
analysed.


title: Is there a monopole problem?

abstract:
  We investigate the high temperature behavior of SU(5) in its minimal version.
We show that there exists a range of parameters of the Higgs potential for
which the symmetry remains broken at high temperature, thus avoiding the phase
transition that gives rise to the overproduction of monopoles . We also show
that in such scenario the thermal production of monopoles can be suppressed in
a wide range of parameters, keeping their number density below the cosmological
limits.


title:
Octet and Decuplet Baryons in the Hadronized Nambu--Jona-Lasinio Model
  with Proper Spin Projection

abstract:
  Octet and Decuplet baryons are described within the hadronized NJL model as
diquark--quark states, which are bound by quark exchange. Including scalar and
axial--vector diquark correlations, we project the previously obtained
relativistic Faddeev equation in a Poincar\'e invariant fashion onto good spin,
using a static approximation to the exchanged quark. The resulting equations
for the spin 1/2 octet and the spin 3/2 decuplet are solved numerically.


title: A note on radiative corrections to $\mu$ and $\tau$ decays

abstract:
  Radiative corrections in the order ${\alpha\over{2\pi}}{{m^2_e}\over
m^2_\mu}$ to $\mu $- and ${\alpha\over{2\pi}}{{m^2_\mu}\over m^2_\tau}$ to
$\tau $- decays are calculated. The decay width is enhanced by $4.48\cdot
10^{-3} ({\alpha\over{2\pi}})$ in the muon case and by $0.283
({\alpha\over{2\pi}})$ for the $\tau \rightarrow \mu \nu_\tau \bar\nu_\mu
(\gamma)$ decay. Influence of these corrections on the electroweak data is
discussed.


title: Physical Program for Photon Colliders

abstract:
  The physical program for the photon linear colliders (PLC) is discussed. We
consider the problems in electroweak theory, hadron physics and QCD, new
particles and interactions. We arrange this program for the main stages of PLC,
which are the parts of an entire program for linear colliders. Some important
unsolved problems are listed.


title: Neutrinoless Double Beta Decay and Physics Beyond the Standard Model

abstract:
  The various mechanisms for neutrinoless double beta decay in gauge theories
are reviewed and the present experimental data is used to set limits on physics
scenarios beyond the standard model. The positive indications for nonzero
neutrino masses in various experiments such as those involving solar,
atmospheric and accelerator neutrinos are discussed and it is pointed out how
some neutrino mass textures consistent with all data can be tested by the
ongoing double beta decay experiments. Finally, the outlook for observable
neutrinoless double beta decay signal in grand unified theories is discussed.


title:
High-p_T Higgs Boson Production at Hadron Colliders to Order(alpha_s
  G_Fermi^3)

abstract:
  We study high--$p_T$ Higgs boson production at hadron colliders to
order($\alpha_s$ $G_F^3$) in hadron collisions. In particular, we investigate
the process $g+q/\bar{q}\ra q/\bar{q}+H$, where $q=u,d,c,s,$ or $b$, for the
LHC (a $\sqrt{s}=$14~TeV, proton--proton collider). Our results are compared to
the order($\alpha_s^3$ $G_F$) calculation. The associated production of a
high--$p_T$ Higgs boson with a $b$--quark or anti--quark is comparable to the
order($\alpha_s^3$ $G_F$) calculation because of the large top quark mass and
the additional contribution of electroweak gauge and Goldstone bosons. The
associated production of light quarks, however, is not significant. We also
comment on new physics effects in the framework of the electroweak chiral
Lagrangian.


title: Low energy Yukawa input parameters for Yukawa coupling Unification

abstract:
  I make a short review of the most recent determinations of the quark masses
and run them to the $M_Z$ energy scale.


title:
An Algorithm to Compute Born Scattering Amplitudes without Feynman
  Graphs

abstract:
  In this paper we suggest an {\it iterative} algorithm to compute
automatically the scattering matrix elements of any given effective lagrangian,
$\Gamma$. By exploiting the relation between $\Gamma$ and the connected Green
function generator, $Z$, we provide a formula which does not require the use of
the Feynman graphs and it is suitable to implement a numerical routine. By
means of this algorithm we have built a relatively simple and fast fortran code
which we have used to calculate, at the tree level, the rate of four fermion
production at LEP I\negthinspace{I} (finding a very good agreement with
previous calculation) with and without the emission of one observable photon.


title: U(1)$_A$ Models of Fermion Masses Without a $\mu$ Problem

abstract:
  We discuss the connection between models of fermion masses and mixing
involving a string-motivated flavor/generation U(1)$_A$ gauge symmetry and the
$\mu$ term. We point out that in a certain class of such models the flavor
physics can provide an appealing solution to the $\mu$ problem, naturally
yielding a $\mu \sim O(m_{_W})$. A simple relationship between the $U(1)_A$
charge $q_{H}$ of the $\mu$-term and the average generational $U(1)_A$ charges
of the down quark and leptonic sectors is derived. Finally, we construct an
explicit model illustrating our results.


title:
Many Higgs Doublet Supersymmetric Model, Flavor Changing Interactions
  and Spontaneous CP Violation

abstract:
  I study many higgs doublet supersymmetric model with spontaneous CP
violation. The damaging flavor changing interactions and large CP violation are
brought under control simultaneously by an approximate PQ symmetry. I relate
the smallness of the CP violating parameter in the kaon system to the small
${m_b \over m_t}$ ratio.


title: Two--loop heavy Higgs correction to Higgs decay into vector bosons

abstract:
  The leading $m_H$ radiative correction to the Higgs decay width into a pair
of weak vector bosons is calculated at the two--loop level, using the
equivalence theorem in Landau gauge. The result indicates the breakdown of
perturbation theory if the Higgs boson is heavier than $\sim 930$ GeV, in spite
of the smallness of the one--loop radiative correction.


title: On dynamical parton distributions of hadrons and photons

abstract:
  The basic concepts and predictions of the `dynamical' GRV parton
distributions for hadrons and photons are discussed. Comparisons of these
predictions with recent experimental results, especially from HERA, are
presented.


title: Hadronic production of baryons, containing two heavy quarks

abstract:
  In the framework of QCD perturbation theory, total and differential cross
sections of the $\Xi_{bc}'$, $\Xi_{bc}^{(*)}$ and $\Xi_{cc}^{(*)}$ baryons
production in gluon collisions are calculated in the leading order over
$\alpha_s$ for the doubly heavy ($b c$) and ($ c c$) diquarks. At both small
and large transverse momenta of the baryons, a use of the mechanism of the
heavy quark fragmentation into the heavy diquark is shown to underestimate the
cross section values in comparison with the exact numerical calculations of
complete set of diagrams. The expected in Tevatron experiments yield of baryons
with two heavy quarks is evaluated as $(1.3\pm 0.3) \cdot 10^5 \,\,
bcq$-baryons and $(1.6\pm 0.3) \cdot 10^4 \,\, ccq$-baryons at $p_T>5$ GeV and
$|y|<1$ of the baryon momentum and rapidity cuts, with account for the
antiparticle yields.


title: Hidden scale dependence in renormalon

abstract:
  In the framework of renormalon consideration, a role of the anomalous
dependence of gluon propagator on the scale $\mu$ is shown for a large number
of quark flavours as well as in the nonabelian theory, where the parameter of
the "running" coupling constant evolution has a hidden dependence on the scale.
A phenomenological matching between the modified renormalon and the static
quark potential is described to fix the renormalon scales.


title: Quark Mass Matrices in Orbifold Models

abstract:
  We study left-right symmetric quark mass matrices whose up- and down-sectors
have the same structure. This type of realistic mass matrices are derived from
orbifold models. We cannot derive some of them by using an extra U(1) symmetry.


title: SABSPV - A Monte Carlo Integrator for Small-Angle Bhabha Scattering

abstract:
  SABSPV is a code designed to perform a theoretical evaluation of small-angle
Bhabha scattering cross sections by suitably matching fixed-order perturbative
calculations and structure-function techniques. The implementation of realistic
experimental triggering conditions is achieved by using Monte Carlo
integration.


title: A Gauge-Independent Approach to Resonant Transition Amplitudes

abstract:
  We present a new gauge-independent approach to resonant transition amplitudes
with nonconserved external currents, based on the pinch technique method. In
the context of $2\to 2$ and $2\to 3$ scattering processes, we show explicitly
that the analytic results derived respect $U(1)_{em}$ gauge symmetry and do not
depend on the choice of the $SU(2)_L$ gauge fixing. Our analytic approach
treats, on equal footing, fermionic as well as bosonic contributions to the
resummed gauge boson propagators, does not contain any residual space-like
threshold terms, shows the correct high-energy unitarity behaviour, admits
renormalization, and satisfies a number of other required properties, including
the optical theorem. Even though our analysis has mainly focused on the
Standard Model gauge bosons, our method can easily be extended to the top
quark, and be directly applied to the study of unstable particles present in
renormalizable models of new physics.


title: Approximate Flavour Symmetries and See-Saw Mechanism

abstract:
  We study the approximate flavour symmetries imposed on the lepton sector
assuming see-saw mechanism as the neutrino mass structure. We apply the
symmetry to various neutrino phenomenologies and obtain constraints on neutrino
masses and mixings.


title:
Leading logarithms of the $b$ quark mass in inclusive $B\to X_s\gamma$
  decay

abstract:
  Part of the order $\alpha_s$ correction to the inclusive $B\to X_s\,\gamma$
photon spectrum is enhanced by $\log(m_b^2/m_s^2)$. We discuss its origin and
sum the corrections proportional to $[\alpha_s\log(m_b^2/\mu^2)]^n$ to all
orders. These are the calculable leading logarithms in the parton fragmentation
functions of a quark or gluon into a photon. Although the gluon fragmentation
into a photon starts only at order $\alpha_s^2$, its contribution is of the
same order as the $s$ quark's in the leading log sum. For not too small values
of the photon energy, the resummation yields a moderate suppression. In the
standard model, the coefficient of the operator whose matrix element gives rise
to such terms is small. A measurement of the photon spectrum around $1\,$GeV
would provide a theoretically clean determination of $C_8$, the Wilson
coefficient of the $b\to s\,g$ operator.


title: Solar Neutrinos and Lepton Mixing

abstract:
  With latest experimental data the solar neutrino problem enters new phase
when crucial aspects of the problem can be formulated in an essentially (solar)
model independent way. Original neutrino fluxes can be considered as free
parameters to be found from the solar neutrino experiments. Resonance flavour
conversion gives the best fit of all experimental results. Already existing
data allow one to constraint both the neutrino parameters and the original
neutrino fluxes. The reconciliation of the solution of the solar neutrino
problem with other neutrino mass hints (atmospheric neutrino problem, hot dark
matter etc.) may require the existence of new very light singlet fermion.
Supersymmetry can provide a framework within which the desired properties of
such a light fermion follow naturally. The existence of the fermion can be
related to axion physics, mechanism of $\mu$-term generation etc..


title: Strange Baryon Production in Heavy Ion Collisions

abstract:
  The rapidity distribution of $\Lambda$ and $\bar{\Lambda}$ produced in
nucleus-nucleus collisions at CERN energies is studied in the framework of an
independent string model - with quark-antiquark as well as diquark-antidiquark
pairs in the nucleon sea. It is shown that, besides the
$\Lambda$-$\bar{\Lambda}$ pair production resulting from the fragmentation of
sea diquarks, final state interactions of co-moving secondaries $\pi + N \to K
+ \Lambda$ and $\pi + \bar{N} \to K + \bar{\Lambda}$ are needed in order to
reproduce the data. Predictions for $Pb$-$Pb$ collisions are presented.


title: Does One Need the Anomaly to Describe the Polarized Structure Functions?

abstract:
  The SLAC data on the p, d and n polarized structure functions are fairly well
reproduced with and without the contribution of the anomaly. The results are
compared with a previous study based mainly on SMC data. The implications on
the solution of the spin-crisis are discussed.


title: Tau-Universality Violation with Light Neutralinos

abstract:
  In a supersymmetric model with the lightest supersymmetric particle (LSP)
$\chi$ in the range of a few hundred MeV's, the decay $\tau {\longrightarrow}
\mu \chi \chi$ is going to be allowed. We investigate the departure from
tau-universality caused by this decay. It is found that the universality
violation in this way can be greater than both non-universal electroweak
radiative corrections and supersymmetric one-loop corrections over a
considerable region of the parameter space allowed by experiments so far. Thus
it suggests a method of constraining the parameter space with light LSP's using
data from tau-factories.


title: Leading Power Corrections in QCD: From Renormalons to Phenomenology

abstract:
  We consider $1/Q$ corrections to hard processes in QCD where Q is a large
mass scale, concentrating on shape variables in $e^{+}e^{-}$ annihilation.
While the evidence for such corrections can be and has been established by
means of the renormalon technique, theory can be confronted with experiment
only after clarifying the properties of the corresponding non-perturbative
contribution. We list predictions based on the universality of the $1/Q$ terms,
and compare them with the existing data. We also identify the scale of the
non-perturbative contributions in terms of jet masses.


title: Exact equations for vacuum correlators in field theory

abstract:
  Stochastic quantization is used to derive exact equations, connecting
multilocal field correlators in the phi^3 theory and gluodynamics. Perturbative
expansion of the obtained equations in the lowest orders is presented.


title: Hadron Radiation in Tau Production and the Leptonic Z Boson Decay Rate

abstract:
  Secondary radiation of hadrons from a tau pair produced in electron positron
collisions may constitute an important obstacle for precision measurements of
the production cross section and of branching ratios. The rate for real and
virtual radiation is calculated and various distributions are presented. For Z
decays a comprehensive analysis is performed which incorporates real and
virtual radiation of leptons. The corresponding results are also given for
primary electron and muon pairs. Compact analytical formulae are presented for
entirely leptonic configurations. Measurements of $Z$ partial decay rates which
eliminate all hadron and lepton radiation are about 0.3\% to 0.4\% lower than
totally inclusive measurements, a consequence of the ${\cal O}(\alpha^2)$
negative virtual corrections which are enhanced by the third power of a large
logarithm.


title:
Electromagnetic form factors of the nucleon in the chiral quark soliton
  model

abstract:
  In this paper we present the derivation as well as the numerical results for
the electromagnetic form factors of the nucleon within the chiral quark soliton
model in the semiclassical quantization scheme. The model is based on
semibosonized SU(2) Nambu -- Jona-Lasinio lagrangean, where the boson fields
are treated as classical ones. Other observables, namely the nucleon mean
squared radii, the magnetic moments, and the nucleon--$\Delta$ splitting are
calculated as well. The calculations have been done taking into account the
quark sea polarization effects. The final results, including rotational $1/N_c$
corrections, are compared with the existing experimental data, and they are
found to be in a good agreement for the constituent quark mass of about 420
MeV. The only exception is the neutron electric form factor which is
overestimated.


title: Top-ology

abstract:
  I compare the anticipated properties of the top quark with what is known
experimentally about the heaviest fermion. I review the scientific
opportunities that will be presented in the near future by copious samples of
top. These include refined tests of electroweak radiative corrections, studies
of the nature of top itself, and exploration of electroweak symmetry breaking.
I conclude by illustrating top's influence in the everyday world.


title:
Constraints on Chiral Perturbation Theory Parameters from QCD
  Inequalities

abstract:
  We explore some of the constraints imposed by positivity of the QCD measure
(Weingarten's inequalities) on the parameters defining chiral perturbation
theory. We find, in particular, that $2 m_q (\mu)\leq B_0(\mu) Z(\mu)$. The use
of further properties of the exact fermion propagator yields information on
some higher order parameters.


title: Forward-jet production in DIS

abstract:
  In this talk I report on some work done in collaboration with Jochen Bartels
and Mark W\"usthoff on forward-jet inclusive production in DIS in the
small-$x_{bj}$ limit. We work in the HERA lab frame and examine the jet
production rate and the lepton-jet azimuthal-angle correlation at small values
of $x_{bj}$.


title: A new ansatz: Fritzsch Mass Matrices with least modification

abstract:
  We investigate how the Fritzsch ansatz for the quark mass matrices can be
modified in the least possible way to accommodate the observed large top quark
mass and the measured values of the CKM elements. As one of the solutions, we
find that the \{23\} and the \{32\} elements of the up quark mass matrix are
unequal. The rest of the assumptions are same as in Fritzsch ansatz. In this
formalism we have an extra parameter i.e. the ratio of the \{{23\}} and the
\{{32\}} element, which gets fixed by the large top quark mass. The predicted
values for $\frac{V_{ub}}{V_{cb}}$ , $\frac{V_{td}}{V_{ts}}$ from this new
ansatz are in the correct experimental range even for the smaller values of
$\tan \beta $. In the end, we write down the $SO(10)$ motivated superpotential
for these new mass matrices.


title: SUSY Unification with Smooth Threshold Behavior

abstract:
  Going beyond the theta function approximation we discuss supersymmetric
unification of gauge couplings with exact decoupling of light and heavy
particles at energy scales below their masses. We find that the Minimal SUSY
model is strongly disfavored while the Missing Doublet Model survives with GUT
scale masses rising into the $10^{18}$ GeV region.


title:
Indirect CP-Violation in the Neutral Kaon System Beyond Leading
  Logarithms

abstract:
  We have calculated the short distance QCD coefficient \eta_3 of the effective
|\Delta S|=2-hamiltonian in the next-to-leading order. Since now all
coefficients \eta_1, \eta_2 and \eta_3 are known beyond the leading log
approximation, one can achieve a much higher precision in the theoretical
analysis of \epsilon_K. The measured value for \epsilon_K$ yields a lower bound
on each of |V_{cb}|, |V_{ub}/V_{cb}|, the top quark mass $m_t$ and the non-
perturbative parameter B_K as a function of the remaining three quantities. We
discuss the implications on the CKM phase \delta, |V_{td}| and the key quantity
for all CP-violating processes, Im \lambda_t = Im [V^*_{ts} V_{td}]. These
quantities and the improved Wolfenstein parameters \bar\rho and \bar\eta are
tabulated and the shape of the unitarity triangle is discussed. We compare the
range for |V_{td}| with the one obtained from the analysis of B^0--\bar{B^0}
mixing. For 0.037 \leq |V_{cb}| \leq 0.043, 0.06 \leq |V_{ub}/V_{cb}| \leq 0.10
and 0.65 \leq B_K \leq 0.85 we find from a combined analysis of \epsilon_K and
the B^0--\bar{B^0} mixing paramater x_d: 49^{\circ} \leq \delta \leq
146^{\circ}, 7.4 \cdot 10^{-3} \leq |V_{td}| \leq 12.4 \cdot 10^{-3}, 0.85
\cdot 10^{-4} \leq \imag \lambda_t \leq 1.60 \cdot 10^{-4}, -0.36 \leq \bar\rho
\leq 0.28 and 0.21 \leq \bar\eta \leq 0.44. We predict the mass difference of
the $B_s^0$ system to lie in the range 6.5 ps^{-1} \leq \Delta m_{B_s} \leq 28
ps^{-1}. Finally we have a 1995 look at the K_L--K_S mass difference.


title:
Bounds on second generation scalar leptoquarks from the anomalous
  magnetic moment of the muon

abstract:
  We calculate the contribution of second generation scalar leptoquarks to the
anomalous magnetic moment of the muon (AMMM). In the near future, E-821 at
Brookhaven will reduce the experimental error on this parameter to $\Delta
a_\mu^{\rm exp}<4\times 10^{-10}$, an improvement of 20 over its current value.
With this new experimental limit we obtain a lower mass limit of
$m_{\Phi_L}>186$\ GeV for the second generation scalar leptoquark, when its
Yukawa-like coupling $\lambda_{\Phi_L}$\ to quarks and leptons is taken to be
of the order of the electroweak coupling $g_2$.


title: A remark on the tau-neutrino mass limit

abstract:
  We point out that the usual experimental upper bounds on the ``tau-neutrino
mass'' do not apply if neutrino mixing is considered. The suppression of the
population of the tau decay spectrum near the end-point, caused by mixing, may
be compensated by an enhancement due to a resonant mechanism of hadronization.
It is necessary therefore to analyse the whole spectrum to infer some limit to
the ``tau-neutrino mass". We argue that, consequently, neutrino mixing evades
the objection to interpret KARMEN anomaly as a heavy sequential neutrino.


title:
Two-loop electroweak corrections to the $\rho$ parameter beyond the
  leading approximation

abstract:
  We show that in the framework of the pinch technique the universal part of
the $\rho$ parameter can be meaningfully defined, beyond one loop. The
universal part so obtained satisfies the crucial requirements of
gauge-independence, finiteness, and process-independence, even when subleading
contributions of the top quark are included. The mechanism which enforces the
aforementioned properties is explained in detail, and several subtle field
theoretical issues are discussed. Explicit calculations of the sub-leading
two-loop corrections of order $O(G_{\mu}^{2}m^{2}_{t}M_{Z}^{2})$ are carried
out in the context of an $SU(2)$ model, with $M_{W}=M_{Z}$, and various
intermediate and final results are reported.


title: Flat Directions and Baryogenesis in Supersymmetric Theories

abstract:
  Flat directions are a generic feature of supersymmetric theories. They are of
cosmological interest because they can lead to coherent production of scalars.
In the early universe such flat directions could be dangerous due to the
potentially large energy density and the late decay of the associated scalars
when they have only $1/M_p$ couplings (Polonyi problem). On the other hand,
flat directions among the standard model fields can carry baryon number and
lead to a possible mechanism for baryogenesis (Affleck Dine baryogenesis). When
considering the cosmological consequences of the flat directions, it is
important to take into account the soft potential with curvature of order the
Hubble constant due to supersymmetry breaking in the early universe. In this
talk, we discuss flat directions, their potential cosmological implications
focusing on Affleck-Dine baryogenesis, and how the standard picture of their
evolution must be modified in the presence of the large supersymmetry breaking
in the early universe.


title:
Long Distance Contribution to $s \to d\gamma$ and Implications for
  $\Omega^-\to \Xi ^-\gamma, B_s \to B_d^*\gamma$ and $b \to s\gamma$

abstract:
  We estimate the long distance (LD) contribution to the magnetic part of the
$s \to d\gamma$ transition using the Vector Meson Dominance approximation
$(V=\rho,\omega,\psi_i)$. We find that this contribution may be significantly
larger than the short distance (SD) contribution to $s \to d\gamma$ and could
possibly saturate the present experimental upper bound on the $\Omega^-\to
\Xi^-\gamma$ decay rate, $\Gamma^{\rm MAX}_{\Omega^-\to \Xi^-\gamma} \simeq
3.7\times10^{-9}$eV. For the decay $B_s \to B^*_d\gamma$, which is driven by $s
\to d\gamma$ as well, we obtain an upper bound on the branching ratio $BR(B_s
\to B_d^*\gamma)<3\times10^{-8}$ from $\Gamma^{\rm MAX}_{\Omega^-\to
\Xi^-\gamma}$. Barring the possibility that the Quantum Chromodynamics
coefficient $a_2(m_s)$ be much smaller than 1, $\Gamma^{\rm MAX}_{\Omega^-\to
\Xi^-\gamma}$ also implies the approximate relation $\frac{2}{3} \sum_i
\frac{g^2_{\psi_i}(0)}{m^2_{\psi_i}} \simeq \frac{1}{2}
\frac{g^2_\rho(0)}{m^2_\rho} + \frac{1}{6}\frac{g^2_\omega(0)}{m^2_\omega}$.
This relation agrees quantitatively with a recent independent estimate of the
l.h.s. by Deshpande et al., confirming that the LD contributions to $b \to
s\gamma$ are small. We find that these amount to an increase of $(4\pm2)\%$ in
the magnitude of the $b \to s \gamma$ transition amplitude, relative to the SD
contribution alone.


title: A New Mass Formula for NG Bosons in QCD

abstract:
  An often used 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. We argue, within the context of the Global Colour Model to QCD,
that this expression is wrong. Analysis of the interplay between the
Dyson-Schwinger equation for the constituent quark effect and the
Bethe-Salpeter equation for the NG boson results in a new mass formula.


title:
On Possibility of Detecting the E-E- -> W-W- Process in the Standard
  Model

abstract:
  We examine the e-e- -> W-W- lepton number violating process in the frame of
the Standard Model with additional right-handed neutrino singlets. We give
results in the framework of the `see-saw' as well as other models, where there
is no relation between neutrino masses and the mixing matrix elements. The
cross section for the `see-saw' models is negligible because they predict in a
natural way very small electron-heavy neutrino mixing angles. However, there
exist other models, in which the electron-heavy neutrino mixing angles are free
parameters and can be large. Taking into account the present experimental
bounds on mixing angles the large cross section for the e-e- -> W-W- is still
acceptable.


title:
The intermediate-mass Standard Model Higgs boson at the NLC: reducible
  and irreducible backgrounds to the Bjorken production channel

abstract:
  Both the reducible and irreducible backgrounds to the Higgs production
channel \eehz\ at a Next Linear Collider (NLC) are studied, for the Standard
Model (\sm) Higgs boson in the intermediate-mass range. A phenomenological
analysis that does not exploit any form of tagging on the Higgs decay products
is assumed.


title: Nonsinglet Contributions to the Structure Function g1 at Small-x

abstract:
  Nonsinglet contributions to the $g_1(x,Q^2)$ structure function are
calculated in the double-logarithmic approximation of perturbative QCD in the
region $x \ll 1$. Double logarithmic contributions of the type $(\alpha_s \ln
^2 (1/x))^k$ which are not included in the GLAP evolution equations are shown
to give a stronger rise at small-x than the extrapolation of the GLAP
expressions. Further enhancement in the small-x region is due to non-ladder
Feynman graphs which in the DLA of the unpolarized structure functions do not
contribute. Compared to the conventional GLAP method (where neither the whole
kinematical region which gives the double logs nor the non-ladder graphs are
taken into account) our results lead to a growth at small-x which, for HERA
parameters, can be larger by up to factor of 10 or more.


title: Description of F2 and the gluon at small x

abstract:
  We give a brief overview of the perturbative QCD description of the proton
deep-inelastic structure function F2(x, Q2) at small x. We discuss GLAP and
BFKL approaches, and then we review progress towards a more unified treatment.


title: Current Conservation in Thermal Field Theory

abstract:
  Within the framework of generalized free field theory at nonzero temperature
we address the problem of current conservation. The formalism of thermo field
dynamics is used to derive a conserved and thermodynamically consistent
physical current operator. Consequences for the calculation of photon emission
rates from a hot plasma are considered briefly.


title:
Relativistic Transport Approach for Nucleus-Nucleus Collisions from SIS
  to SPS Energies

abstract:
  We formulate a covariant transport approach for high energy nucleus-nucleus
collisions where the real part of the nucleon selfenergies is fitted to nuclear
matter properties which are evaluated on the basis of a NJL-type Lagrangian for
the quark degrees of freedom. The parameters of the quark-model Lagrangian are
fixed by the Gell-Mann, Oakes and Renner relation, the pion- nucleon
$\Sigma$-term, the nucleon energy as well as the nuclear binding energy at
saturation density $\rho_0$. We find the resulting scalar and vector
selfenergies for nucleons to be well in line with either Dirac-Brueckner
computations for $\rho \leq 2 \rho_0$ or those from the phenomenological
optical potential when accounting for a swelling of the nucleon at finite
nuclear matter density. The meson-baryon interaction density is modelled to
describe a decrease of the meson mass with baryon density. The imaginary part
of the hadron selfenergies is determined by a string fragmentation model which
accounts for the in-medium mass of hadrons in line with the 'chiral' dynamics
employed. The applicability of the transport approach is demonstrated in
comparison with experimental data from SIS to SPS energies. The enhancement of
the K$^+/\pi^+$ ratio in A + A collisions compared to p + A reactions at AGS
energies is reproduced within the 'chiral' dynamics. Furthermore, detailed
predictions for the stopping in Pb + Pb collisions at 153 GeV/A are presented.


title: Left-Right Symmetry Breaking in NJL Approach

abstract:
  We study left-right symmetric models which contain only fermion and gauge
boson fields and no elementary scalars. The Higgs bosons are generated
dynamically through a set of gauge- and parity-invariant 4-fermion operators.
It is shown that in a model with a composite bi-doublet and two triplet scalars
there is no parity breaking at low energies, whereas in the model with two
doublets instead of two triplets parity is broken automatically regardless of
the choice of the parameters of the model. For phenomenologically allowed
values of the right-handed scale a tumbling symmetry breaking mechanism is
realized in which parity breaking at a high scale $\mu_R$ propagates down and
eventually causes the \EW symmetry breaking at the scale $\mu_{EW}\sim
100~GeV$. The model exhibits a number of low and intermediate mass Higgs bosons
with certain relations between their masses. In particular, the components of
the $SU(2)_L$ Higgs doublet $\chi_L$ are pseudo--\GBs of an accidental
(approximate) $SU(4)$ symmetry of the Higgs potential and therefore are
expected to be relatively light.


title: Decay of Z into Two Light Higgs Bosons

abstract:
  If the standard electroweak gauge model is extended to include two or more
Higgs doublets, there may be a neutral Higgs boson $h$ which is light (with a
mass of say 10 GeV) but the $hZZ$ coupling is suppressed so that it has so far
escaped experimental detection. However, the effective $hhZZ$ coupling is
generally unsuppressed, hence the decay of Z into two light Higgs bosons plus a
fermion-antifermion pair may have an observable branching fraction, especially
if $h$ decays invisibly as for example in the recently proposed doublet Majoron
model.


title:
Off-shell $W$-pair production in $e^+ e^-$-annihilation. Initial state
  radiation

abstract:
  With a current-splitting technique, we calculate the gauge-invariant
initial-state radiation to order \oalf\ with soft-photon exponentiation for on-
and off-shell $W$-pair production. This result generalizes the convolution
formula, which is known from the description of the $Z$ resonance, to the case
of the production of two $W$-bosons. After up to eightfold analytical
integrations, a sufficiently smooth integral over three invariant masses
remains to be treated numerically. Including the Coulomb singularity, the
largest corrections are covered. We discuss the corrections in a large energy
range up to $\sqrt{s}$=1~TeV and draw numerical conclusions on their influence
on the $W$-mass determination at LEP~200. Table~1 and figure~5 are revised
after correcting the analytical formulae for the nonuniversal corrections.


title:
Leptonic QED Corrections to the process $ep \longrightarrow eX$ in
  Jaquet-Blondel variables

abstract:
  For the study of deep inelastic scattering at HERA, the use of Jaquet-Blondel
variables is advantageous in several respects. We calculate the complete
leptonic ${\cal O}(\alpha)$ QED corrections for the reaction $ep \to eX$ in
these variables. All but one phase space integrations are performed
analytically. After exponentiation of soft photon corrections, an accuracy of
at least 1% is matched. Numerical results are presented and compared to
estimates based on the leading logarithmic approximation. Equation (17) is
corrected in accordance with equation (7.44) of DESY 94--115. The misprint did
not influence the numerics.


title: Vacuum Functional and Fermion Condensate in the Massive Schwinger Model

abstract:
  We derive a systematic procedure of computing the vacuum functional and
fermion condensate of the massive Schwinger model via a perturbative expansion
in the fermion mass. We compute numerical results for the first nontrivial
order.


title: Space-like Penguin Effects in $B \to PP$ Decays

abstract:
  The space-like penguin contributions to branching ratios and CP asymmetries
in charmless decays of $B$ to two pseudoscalar mesons are studied using the
next-to-leading order low energy effective Hamiltonian. Both the gluonic
penguin and the electroweak penguin diagrams are considered. We find that the
effects are significant.


title: Nuclear Neutron Haloes as Seen by Antiprotons

abstract:
  Nuclear interactions of antiprotons in atomic states are discussed. The total
as well as partial widths for single nucleon capture events are calculated.
These are compared to the X-ray and recent single nucleon capture data. The
rates of the neutron or proton captures test nuclear density distributions at
the extreme nuclear surface. Recently found cases of neutron and proton haloes
are analysed.


title:
Naturalness Constraints in Supersymmetric Theories with Non-Universal
  Soft Terms

abstract:
  In the absence of universality the naturalness upper limits on supersymmetric
particle masses increase significantly. The superpartners of the two light
generations can be much heavier than the weak scale without extreme
fine-tunings; they can weigh up to about 900 GeV --- or even up to 5 TeV, if
SU(5) universality is invoked. This supresses sparticle-mediated rare processes
and consequently ameliorates the problem of supersymmetric flavor violations.
On the other hand, even without universality, the gluino and stop remain below
about 400 GeV while the charginos and neutralinos are likely to be accessible
at LEP2.


title:
A new method of determining $|V_{ub}|$ by the processes $\bar{B} \to
  \rho l \bar{\nu}$ and $\bar{B} \to K^* l \lbar$

abstract:
  The differential decay width of the process $\bar{B} \rightarrow \rho l
\bar{\nu}$ is related to that of the process $\bar{B} \rightarrow K^* l \lbar$
by using $SU(3)$-flavor symmetry and the heavy quark symmetry. The ratio of the
Kobayashi-Maskawa matrix elements is obtained in the zero recoil limit of
$\rho$ and $K^*$, allowing a determination of $|V_{ub}|$.


title: Hadron Spectra for Semileptonic Heavy Quark Decay

abstract:
  We calculate the leading perturbative and power corrections to the hadronic
invariant mass and energy spectra in semileptonic heavy hadron decays. We apply
our results to the $B$ system. Moments of the invariant mass spectrum, which
vanish in the parton model, probe gluon bremsstrahlung and nonperturbative
effects. Combining our results with recent data on $B$ meson branching ratios,
we obtain a lower bound $\bar\Lambda>410\,{\rm MeV}$ and an upper bound
$m_b^{\rm pole}<4.89\,$GeV. The Brodsky-Lepage-Mackenzie scale setting
procedure suggests that higher order perturbative corrections are small for
bottom decay, and even tractable for charm decay.


title: A Dynamical Model for Nuclear Structure Functions

abstract:
  The dynamical origins of the EMC effect are studied. We conclude that a
swelling in size of a bound nucleon as well as nuclear binding plays an
important r\^ole in determining the parton distributions within a bound
nucleon. We find that the distortion of nucleon structure functions in nuclei
can be simply explained with a few fundamental nuclear parameters.


title: Two-loop Corrections for Electroweak Processes

abstract:
  Theoretical uncertainties affecting electroweak observables are reviewed and
the relevance of two-loop electroweak radiative corrections for the precision
tests of the Standard Model is discussed.


title:
Effective Field Theory for a Heavy Higgs: a Manifestly Gauge Invariant
  Approach

abstract:
  For large values of the Higgs boson mass the low energy structure of the
gauged linear sigma model in the spontaneously broken phase can adequately be
described by an effective field theory. In this work we present a manifestly
gauge invariant technique to explicitly evaluate the corresponding effective
Lagrangian from the underlying theory. In order to demonstrate the application
of this functional method, the effective field theory of the abelian Higgs
model is thoroughly analyzed. We stress that this technique does not rely on
any particular property of the abelian case. The application to the non-abelian
theory is outlined.


title: Hyperon Masses in Nuclear Matter

abstract:
  We analyze hyperon and nucleon mass shifts in nuclear matter using chiral
perturbation theory. Expressions for the mass shifts that include strong
interaction effects at leading order in the density are derived. Corrections to
our results are suppressed by powers of the Fermi momentum divided by either
the chiral symmetry breaking scale or the nucleon mass. Our work is relevant
for neutron stars and for large hypernuclei.


title: Color-Singlet Technipions at the Tevatron

abstract:
  I discuss production and detection at the Tevatron $\pbarp$ collider of pairs
of light ($\mpi = 100$--$200\,\gev$) color--singlet technipions that are
expected in all nonminimal models of technicolor. Gluon fusion production rates
can be as large as $\CO(1\,\pb)$. Topcolor--assisted technicolor is required to
prevent top quarks from decaying as $t \ra \tpip b$. An intriguing consequence
of this is that the decays $\tpip \ra \tau^+ \nu_\tau$, $c \ol s$ and $\tpiz
\ra b \ol b$ may also be suppressed so that $\tpip \ra W^+ \gamma$ and $\tpiz
\ra \gamma\gamma$ are significant. These modes have spectactular signatures at
the Tevatron.


title: Exploring New Physics with CP Violation in Neutral D and B Decays

abstract:
  If New Physics contributes significantly to neutral meson mixing, then it is
quite likely that it does so in a CP violating manner. In $D^0-\bar D^0$ mixing
measured through $D^0\rightarrow K^+\pi^-$, CP violation induces a term
$\propto te^{-\Gamma t}$ with important implications for experiments. For
$B_s-\bar B_s$ mixing, a non-vanishing CP asymmetry (above a few percent)
$a_{CP}(B_s \rightarrow D_s^+ D_s^-)$ is a clear signal of New Physics.
Interestingly, this would test precisely the same Standard Model ingredients as
the question of whether $\alpha+\beta+\gamma=\pi$.


title:
Combined Fit of Low Energy Constraints to Minimal Supersymmetry and
  Discovery Potential at LEP II

abstract:
  Within the Constrained Minimal Supersymmetric Standard Model (CMSSM) it is
possible to predict the low energy gauge couplings and masses of the
3.generation particles from a few parameters at the GUT scale, and electroweak
symmetry breaking. Further constraints can be derived from the branching ratio
for the radiative (penguin) decay of the b-quark into s gamma and the lower
limit on the lifetime of the universe, which requires the dark matter density
due to the Lightest Supersymmetric Particle (LSP) not to overclose the
universe. From a chi^2 analysis, in which these constraints can be considered
simultaneously, one can calculate the probability for each point in the MSGUT
parameter space. The recently measured top quark mass prefers two solutions for
the mixing angle in the Higgs sector: tan beta in the range between 1 and 3 or
alternatively tan beta approx 25-50. For both cases we find a unique chi^2
minimum in the parameter space. For the low tan beta solution these additional
constraints can be fulfilled simultaneously for quite a large region of the
parameter space. In contrast, for the high tan beta solution the correct value
for the b --> s gamma rate is obtained only for small values of the gaugino
scale. For particles, which are most likely to have masses in the LEP II energy
range, the cross sections are given for the various energy scenarios at LEP II.
The highest LEP II energies (205 GeV) are just high enough to cover a large
region of the preferred parameter space, both for the low and high tan beta
solutions. For low tan beta the production of the lightest Higgs boson, which
is expected to have a mass below 115 GeV, is the most promising channel, while
for large tan beta the production of charginos and/or neutralinos covers the
preferred parameter space.


title: The Crucial Role of $\omega \pi^+$ Production in the $D_s^+$ Decay

abstract:
  In this paper the relevance of non-spectator decays of charm particles is
analysed and some crucial tests for it are suggested.


title:
Coulomb corrections for Bose-Einstein correlations in whole momentum
  transfer region: Proposal of seamless fitting

abstract:
  We applied an improved Coulomb correction method developed by us recently to
data on identical KK-pairs production in S + Pb and p + Pb reactions at 200
GeV/c obtained by NA44 Collaboration. To analyse the whole range of the
momentum transfers measured the method of "seamless fitting" has been proposed
and used together with the asymptotic expansion formula for the Coulomb wave
function. We found that such Coulomb corrections lead sometimes to different
than previously reported (by NA44 Collaboration) interaction region and
strongly influence the long range correlations.


title:
Strong Constraints on the Parameter Space of the MSSM from Charge and
  Color Breaking Minima

abstract:
  A complete analysis of all the potentially dangerous directions in the
field-space of the minimal supersymmetric standard model is carried out. They
are of two types, the ones associated with the existence of charge and color
breaking minima in the potential deeper than the realistic minimum and the
directions in the field-space along which the potential becomes unbounded from
below. The corresponding new constraints on the parameter space are given in an
analytic form, representing a set of necessary and sufficient conditions to
avoid dangerous directions. They are very strong and, in fact, there are
extensive regions in the parameter space that become forbidden. This produces
important bounds, not only on the value of $A$, but also on the values of $B$
and $M_{1/2}$. Finally, the crucial issue of the one-loop corrections to the
scalar potential has been taken into account in a proper way.


title: Leptoproduction of Heavy Quarks

abstract:
  There are presently two approaches to calculating heavy quark production for
the deeply inelastic scattering process in current literature. The conventional
fixed-flavor scheme focuses on the flavor creation mechanism and includes the
heavy quark only as a final state particle in the hard scattering cross
section; this has been computed to next-to-leading order--\alphas^2. The more
recently formulated variable-flavor scheme includes, in addition, the flavor
excitation process where the initial state partons of all flavors contribute
above their respective threshold, as commonly accepted for calculations of
other high energy processes; this was initially carried out to leading
order--\alphas^1. We first compare and contrast these existing calculations. As
expected from physical grounds, the next-to-leading-order fixed-flavor scheme
calculation yields good results near threshold, while the leading-order
variable-flavor scheme calculation works well for asymptotic Q^2. The quality
of the calculations in the intermediate region is dependent upon the x and Q^2
values chosen. An accurate self-consistent QCD calculation over the entire
range can be obtained by extending the variable-flavor scheme to
next-to-leading-order. Recent work to carry out this calculation is described.
Preliminary numerical results of this calculation are also presented for
comparison.


title:
BRST Quantization, Strong CP Violation, the U(1) Problem and $\theta$
  Vacua

abstract:
  The non-perturbative implications of BRST quantization are examined for
$\theta$ vacua and related issues. Strong CP violation is shown to be absent
for QCD in the BRST formalism. Previous evidence for CP violation is
reexamined, and much of it is found to be inconclusive. It is proposed that
some lattice calculations be redone to clarify the situation. For the U(1)
problem, difficulties are encountered for a conventional solution within the
BRST framework. We also find problems with previous instanton and non-instanton
approaches.


title: A Mechanism for Instanton Induced Chiral Symmetry Breaking in QCD

abstract:
  We propose a mechanism for instanton induced chiral symmetry breaking in QCD
with fundamental scalars. The model Lagragian that we use has the same symmetry
properties as QCD. The scalar fields develop vacuum expectation values at a
non-trivial minimum and generate masses for thhe light quarks. The minimization
condition is also used to break the $SU(N_f)$ flavour symmetry in order to make
the $s$ quark heavier than the two lighter ones. Thus a vacuum of the theory
that is not chirally invariant is obtained.


title:
Virtual Compton Scattering Off Protons at Moderately Large Momentum
  Transfer

abstract:
  The amplitudes for virtual Compton scattering off protons are calculated
within the framework of the diquark model in which protons are viewed as being
built up by quarks and diquarks. The latter objects are treated as
quasi-elementary constituents of the proton. Virtual Compton scattering,
electroproduction of photons and the Bethe-Heitler contamination are discussed
for various kinematical situations. We particularly emphasize the r\^ole of the
electron asymmetry for measuring the relative phases between the virtual
Compton and the Bethe-Heitler amplitudes. It is also shown that the model is
able to describe very well the experimental data for real Compton scattering
off protons.


title: Predicting Vckm with Universal Strength of Yukawa Couplings

abstract:
  We study the question of calculability of the Cabibbo-Kobayashi-Maskawa (CKM)
matrix elements within the framework of universal strength for Yukawa couplings
(USY). We first classify all solutions leading to $m_u=m_d=0$ within USY and
then suggest a highly predictive ansatz where all the moduli of the CKM matrix
elements are correctly predicted in terms of quark mass ratios, with no free
parameters.


title: Three-body relativistic flux tube model from QCD Wilson-loop approach

abstract:
  First we review the derivation of the relativistic flux tube model for a
quark-antiquark system from Wilson area law as we have given in a preceding
paper. Then we extend the method to the three-quark case and obtain a
Lagrangian corresponding to a star flux tube configuration.
  A Hamiltonian can be explicitly constructed as an expansion in $1 / m^2$ or
in the string tension $\sigma$. In the first case it reproduces the Wilson loop
three-quark semirelativistic potential; in the second one, very complicated in
general, but it reproduces known string models for slowly rotating quarks.


title: Spin effects in lepton-nucleon reactions

abstract:
  We summarize some theoretical issues, which have been considered of special
importance in the discussions of the above working group session.


title: Charm meson radiative decays

abstract:
  Combining heavy quark effective theory and the chiral Lagrangian approach we
investigate D meson radiative decays. First, we reanalyse $D^{*} \rightarrow D
\gamma$ decays using heavy quark spin symmetry, chiral symmetry Lagrangian, but
including also the light vector mesons. Then, we calculate branching ratios $D
\rightarrow V \gamma$. We make some comments on the Cabbibo suppressed decays
$D \to \rho / \omega \gamma$ and the branching ratios of $D \rightarrow P P
\gamma$ decays.


title: Towards the Control over Electroweak Penguins in Nonleptonic B-Decays

abstract:
  We present strategies for determining electroweak penguins from experimental
data. Using the CKM-angle $\gamma$ as one of our central inputs and making some
reasonable approximations, we show that the $\bar b\to\bar s$ electroweak
penguin amplitude can be determined in a two-step procedure involving i)
BR$(B^+\to\pi^0K^+)$, BR$(B^-\to\pi^0K^-)$, BR$(B^+\to\pi^+K^0)$ and ii) either
BR$(B^0_d\to\pi^-K^+)$, BR$(\bar B^0_d\to\pi^+K^-)$ or $\acp(t)$ of the mode
$B_s\to K^+K^-$. The determination employing the $B\to\pi K$ transitions is not
affected by $SU(3)$-breaking effects. Relating the $\bar b\to\bar s$
electroweak penguin amplitude to the $\bar b\to\bar d$ case through $SU(3)$
symmetry arguments, we are in a position to estimate the electroweak penguin
uncertainty affecting the extraction of the CKM-angle $\alpha$ by using isospin
relations among $B\to\pi\pi$ decays. Our results allow in principle the
determination of CKM-phases in a variety of $B$-decays.


title: Constraints on QCD Sum-rules from the H\"older Inequalities

abstract:
  A new technique based on H\"older's integral inequality is applied to QCD
sum-rules to provide fundamental constraints on the sum-rule parameters. These
constraints must be satisfied if the sum-rules are to consistently describe
integrated physical cross-sections, but these constraints do not require any
experimental data and therefore can be applied to any hadronic spectral
function. As an illustration of this technique the Laplace sum-rules of the
light-quark correlation function for the vector and the axial-vector currents
are examined in detail. We find examples of inconsistency between the
inequalities and sum-rule parameters used in some previous analyses of the
vector and axial-vector channels.


title: A General Higgs Sector: Constraints and Phenomenology

abstract:
  We have investigated some phenomenological aspects of an $SU(2)\times U(1)$
scenario where scalars belonging to arbitrary representations of $SU(2)$ are
involved in electroweak symmetry breaking. The resulting interaction terms are
derived. Some constraints are obtained on the arbitrary scalar sector from the
requirement of tree-level unitarity in longitudinal gauge boson scattering. We
also show that, in cases where the scalars ensure $\rho=1$ at tree-level,
useful restrictions on their parameter space follow from precision measurements
of the $Zb\bar b$ vertex. Finally, some salient features about the production
of such Higgs bosons in $e^+e^-$ collision are discussed.


title: Condensation of bosons in kinetic regime

abstract:
  We study the kinetic regime of the Bose-condensation of scalar particles with
weak $\lambda \phi^4$ self-interaction. The Boltzmann equation is solved
numerically. We consider two kinetic stages. At the first stage the condensate
is still absent but there is a nonzero inflow of particles towards ${\bf p} =
{\bf 0}$ and the distribution function at ${\bf p} ={\bf 0}$ grows from finite
values to infinity in a finite time. We observe a profound similarity between
Bose-condensation and Kolmogorov turbulence. At the second stage there are two
components, the condensate and particles, reaching their equilibrium values. We
show that the evolution in both stages proceeds in a self-similar way and find
the time needed for condensation. We do not consider a phase transition from
the first stage to the second. Condensation of self-interacting bosons is
compared to the condensation driven by interaction with a cold gas of fermions;
the latter turns out to be self-similar too. Exploiting the self-similarity we
obtain a number of analytical results in all cases.


title:
Kt-Factorization vs. Renormalization Group: A small-x Consistency
  Argument

abstract:
  The consistency of the BFKL equation with the renormalization group is
investigated at next-to-leading log-x level.By use of Kt-factorization, it is
found that,besides next-to-leading small-x resummation formulae, a leading,
x-dependent redefinition of initial quarks and gluons is needed. Its
interpretation and phenomenological relevance are discussed.


title: Strangelets with finite entropy

abstract:
  Strangelets with non-zero entropy are studied within the MIT bag model.
Explicit account is taken of the constraints that strangelets must be color
neutral and have a fixed total momentum. In general, masses increase with
increasing entropy per baryon, and the constraints work so as to increase
masses further. This has an important destabilizing effect on strangelets
produced in ultrarelativistic heavy ion collisions.


title: How to Determine the Pion Cloud of the Constituent Quark

abstract:
  We calculate the differential cross section for semi-inclusive pion
production in electron proton reactions using a model where the physical quark
fluctuates with some probability to quark plus pion. The kinematic regions for
a determination of this `pion cloud' are evaluated.


title:
An Isospin Analysis of $CP$ Violation in $B_{d}\to D\pi$, $D^{*}\pi$ and
  $D\rho$

abstract:
  By use of current experimental data, we carry out an isospin analysis of the
weak decays $B\rightarrow D\pi, D^{*}\pi$ and $D\rho$. It is found that only in
$B\rightarrow D\rho$ the strong phase shift of two different isospin amplitudes
can be approximately neglected. We derive some useful relations between the
$CP$-violating measurables and the weak and strong transition phases, and
illustrate the different effects of final-state interactions on $CP$ violation
in $B_{d}\rightarrow D\pi, D^{*}\pi$ and $D\rho$.


title: Excited Heavy Mesons Beyond Leading Order in the Heavy Quark Expansion

abstract:
  We examine the decays of excited heavy mesons, including the leading power
corrections to the heavy quark limit. We find a new and natural explanation for
the large deviation of the width of the $D_1(2420)$ from the heavy quark
symmetry prediction. Our formalism leads to detailed predictions for the
properties of the excited bottom mesons, some of which recently have been
observed. Finally, we present a detailed analysis of the effect of power
corrections and finite meson widths on the angular distributions which may be
measured in heavy meson decays.


title: Thermal Mixing of Phases: Numerical and Analytical Studies

abstract:
  The dynamics of phase transitions plays a crucial r\^ole in the so-called
interface between high energy particle physics and cosmology. Many of the
interesting results generated during the last fifteen years or so rely on
simplified assumptions concerning the complex mechanisms typical of
nonequilibrium field theories. In particular, whenever first order phase
transitions are invoked, the metastable background is assumed to be
sufficiently smooth to justify the use of homogeneous nucleation theory in the
computation of nucleation rates of critical bubbles. In this talk I present the
results of numerical simulations which were designed to quantify
``smoothness''; that is, how the contribution from nonperturbative subcritical
fluctuations may spoil the homogeneity assumption of nucleation theory. I then
show how the numerical results can be understood {\it quantitatively} in terms
of a simple analytical model of subcritical thermal fluctuations. Encouraged by
the success of the model in matching the numerical results, I apply it to the
standard model electroweak phase transition.


title:
The Light, the Heavy and the Superheavy --- a Nonabelian Flavor Symmetry
  for the Full Hierarchy

abstract:
  We give a preliminary report of a new quark mass matrix model basing on a
$SU(5)\otimes SU(5)\otimes Q_{12}$ symmetry embedding into a fully gauged
$SU(5)\otimes SU(5)\otimes SU(2)$.~\cite{fk} The two $SU(5)$'s contain the
standard SUSY $SU(5)$ as a diagonal subgroup, while the $Q_{12}$ or $SU(2)$ is
horizontal. Starting by assuming a judiciously-chosen set of chiral
supermultiplets, and a pattern of spontaneous symmetry breaking, we obtain the
low-energy chiral fermions together with a spectrum of superheavy fermions at
two different scales. The latter mediate Froggatt-Nielsen tree graphs that give
rise to a phenomenologically viable effective quark mass matrix texture. The
model is the first example of a nontrivial combination of supersymmetry without
R-parity, gauged nonabelian horizontal symmetry and
unification/anti-unification. It is expected to have some very interesting
features in SUSY-GUT phenomenology.


title:
Dimensional Reduction in Nambu-Jona-Lasinio Model in External
  Chromomagnetic Field

abstract:
  The effective dimensional reduction of fermion-antifermion pairing dinamics
in Nambu-Jona-Lasinio model in external chromomagnetic field is considered. It
is shown that such a field causes the reduction of the space dimension by one
unit in contrast to an ordinary magnetic field which reduces it by two units.
The enhancement of the dynamical chiral symmetry breaking due to the reduction
is discussed.


title:
A Note on the Effective Soft SUSY-Breaking Lagrangian Below the GUT
  Scale

abstract:
  I consider the superfield derivation of the effective theory of softly broken
supersymmetry below the GUT scale. I point out the role of supergauge
invariance in determining the form of the result, which is rather restricted in
interesting classes of models. As an example I discuss sfermion mass splittings
for matter embedded in a single GUT multiplet. Interesting differences arise
between the cases of $SU(5)$, $SO(10)$ and $E_6$.


title: A scalar gluonium contribution to $K\rightarrow\pi\pi$ decay

abstract:
  We study a new $K\rightarrow\pi\pi$ decay channel with gluons in intermediate
state which is normally neglected within the factorization framework. Both
short-distance and long-distance parts of the amplitude are calculated. The
chiral Lagrangian approach is used for obtaining the long-distance
contribution. The nonperturbative contribution gives an additional enhancement
to $K\rightarrow\pi\pi$ decay amplitude with $\Delta I=1/2$. A sizable
violation of factorization in the $p^4$ order of chiral perturbation theory is
found.


title: Would a Light Higgs Detection Imply New Physics?

abstract:
  Depending on the Higgs-boson and top-quark masses, $M_H$ and $M_t$, the
effective potential of the Standard Model can develop a non-standard minimum
for values of the field much larger than the weak scale. In those cases the
standard minimum becomes metastable and the possibility of decay to the
non-standard one arises. Comparison of the decay rate to the non-standard
minimum at finite (and zero) temperature with the corresponding expansion rate
of the Universe allows to identify the region, in the ($M_H$, $M_t$) plane,
where the Higgs field is sitting at the standard electroweak minimum. Since
that region depends on the cutoff scale $\Lambda$, up to which we believe the
Standard Model, the discovery of the Higgs boson, mainly at LEP-200, might put
an upper bound (below the Planck scale) on the scale of new physics $\Lambda$.


title: The effects of the kaonic cloud on the neutron electric form factor

abstract:
  We investigate the effects of mesonic clouds on neutron electric and nucleon
strange form factors in the framework of the chiral quark soliton model. We
present a mechanism to identify the mesonic clouds and their Yukawa tail in the
polarized Dirac sea. We find that, assuming hedgehog structures and
semiclassical quantization, the neutron electric and the nucleon strange form
factors are noticeably dependent on the value of the mass parameter in the
Yukawa tails. A method is described to treat these Yukawa tails correctly. A
hybrid way of calculating the neutron electric form factor is presented, which
gives operationally both meson fields the proper Yukawa tails. This yields
noticeably better agreement with experiment than previous calculations in the
chiral quark soliton model and turns out to reproduce the data well.


title: The Low Energy $\pi\,\pi$ Amplitude to One and Two Loops

abstract:
  The low-energy $\pi\pi$ amplitude is computed explicitly to two-loop accuracy
in the chiral expansion. It depends only on six independent (combinations of)
low-energy constants which are not fixed by chiral symmetry. Four of these
constants are determined {\it via} sum rules which are evaluated using $\pi\pi$
scattering data at higher energies. Dependence of the low-energy phase shifts
and of the threshold parameters on the remaining two constants (called $\alpha$
and $\beta$) are discussed and compared to the existing data from $K_{l4}$
experiments. Using generalised $\chi$PT, the constants $\alpha$ and $\beta$ are
related to fundamental QCD parameters such as the quark condensate $\langle
0|\bar{q}q|0\rangle$ and the quark mass ratio $m_s/\widehat{m}$. It is shown
that forthcoming accurate low-energy $\pi\pi$ data can be used to provide, for
the first time, experimental evidence in favour of or against the existence of
a large quark-antiquark condensate in the QCD vacuum.


title: About the behaviour of QCD Pomeron in deep inelastic scattering

abstract:
  The paper presents the QCD description of the small $x$ behaviour of parton
distribution functions in the leading twist of Wilson operator product
expansion. The smooth transition between the cases of the soft and hard
Pomerons is obtained. The results are in qualitative agreement with deep
inelastic experimental data.


title: Momentum Conservation at Small x

abstract:
  We discuss how momentum conservation is implemented in perturbative
computations based on expansions of anomalous dimensions appropriate at small
$x$. We show that for any given choice of $F_2$ coefficient functions there
always exists a factorization scheme where the gluon is defined in such a way
that momentum is conserved at next to leading order.


title:
Matching Perturbative and Non-Perturbative Physics With Power Accuracy
  in Heavy-Quark Effective Theory

abstract:
  I discuss a scheme to match perturbative and non-perturbative physics with
power accuracy in the heavy-quark effective theory. I elaborate on two
important aspects of the scheme: 1) a multi-loop subtraction of soft
contributions from the perturbation series in the pole mass, 2) a perturbative
regularization of the linearly-divergent heavy-quark self-energy in the lattice
formulation of the heavy-quark effective theory.


title: A Minimal Four-Family Supergravity Model

abstract:
  We investigate the phenomenology of minimal four-family MSSM supergravity
theories containing an additional generation of heavy fermions along with their
superpartners. We demand: gauge coupling constant unification at high energy
scales; perturbative values for all Yukawa couplings for energy scales $\leq
\mgut$; radiative electroweak symmetry breaking via renormalization group
evolution; and a neutral LSP. The perturbative constraints imply a light
fourth-family quark and lepton spectrum, and $\tanb\lsim 3$. The lightest
CP-even Higgs mass is increased. Fourth-family Yukawa coupling contributions to
the evolution of scalar masses lead to unexpected mass hierarchies; \eg\ the
$\staupone$ is generally the lightest slepton and the lightest squark is the
$\wt\bpr_1$. A significant lower bound is placed on the gluino mass by the
requirement that the $\staupone$ not be the LSP. Sleptons of the first two
families are much more massive compared to the LSP and other neutralinos and
charginos than in the three-family models, and could easily lie beyond the
reach of a $\sqrt s=500\gev$ $\epem$ collider. Relations between slepton masses
and gaugino masses are shown to be very sensitive to the presence of a fourth
generation. The most important near-future experimental probes of the
four-family models are reviewed. A scenario with $\mt\sim\mw$ and $t\rta {\wt
t_1}\cnone$ is shown to be inconsistent with universal soft-SUSY-breaking
boundary conditions. Full four-family evolution of $\alpha_s$ is shown to lead
to a significant enhancement in inclusive jet and di-jet spectra at Tevatron
energies when all sparticle masses are near their lower bounds.


title: New issues in quark-lepton symmetry

abstract:
  Two models incorporating different forms of spontaneously broken quark-lepton
symmetry are discussed. Both models are constructed so that quark-lepton
symmetry can be broken at as low an energy scale as phenomenology allows, thus
maximising their testability. The first model uses the Pati-Salam gauge group
SU(4)$\otimes$SU(2)$_L\otimes$SU(2)$_R$. The main analysis presented here
concerns large threshold corrections to the $m_b = m_{\tau}$ tree-level mass
relation. The second model is a new and simplified theory using discrete
quark-lepton symmetry which has a very economical Higgs sector and elegantly
avoids a potential quark-lepton mass relation problem.


title:
SU(3)-Flavor-Analysis of Nonfactorizable Contributions to $D \to Pp$
  Decays

abstract:
  We study charm D - meson decays to two pseudoscalar mesons in Cabibbo favored
mode employing SU(3)-flavor for the nonfactorizable matrix elements. Using
$D\rightarrow \bar K \pi$ and $D_{s} \rightarrow \bar K K$ to fix the reduced
matrix elements, we obtain a consistent fit for $ \eta$ and $ \eta'$ emitting
decays of $D$ and $ D_{s}$ mesons.


title: Is $f_0(1500)$ a Scalar Glueball?

abstract:
  Following the discovery of two new scalar mesons, $f_0(1370)$ and $f_0(1500)$
at the Low Energy Antiproton Ring at CERN, we argue that the observed
properties of this pair are incompatible with them both being $\qqbar$ mesons.
We show instead that $f_0(1500)$ is compatible with the ground state glueball
expected around 1500 MeV mixed with the nearby states of the $0^{++}$
$Q\bar{Q}$ nonet. Tests of this hypothesis include the prediction of a further
scalar state, $f_0'(1500 - 1800)$ which couples strongly to $K\bar{K}$,
$\eta\eta$ and $\eta\eta'$. Signatures for a possible tensor glueball at $\sim
$2 GeV are also considered.


title: Six--jet decay of off--shell WW pairs at $e^+ e^-$ colliders

abstract:
  Six--jet events via WW pairs, $e^+e^- \ar W^+W^- \ar q_1 \overline{q_1} q_2
\overline{q_2} g g$ are studied at tree level using helicity amplitudes. This
is the dominant production mechanism for six--jet final states at Lep II
energy. ISR effects are taken into account. Total production rates as a
function of $y_{cut}$ are given. The relevance of these processes for the issue
of colour reconnection is discussed. The cross section for five--jet production
via WW pairs at Lep II is also presented.


title:
Nucleon electric polarizability in soliton models and the role of the
  seagull terms

abstract:
  The full Hamiltonian of the soliton models contains no electric seagull
terms. Here it is shown that if one restricts the fields to the collective
subspace then electric seagull terms are induced in the effective Hamiltonian.
These effective seagull contributions are consistent with gauge invariance.
They also reproduce the leading nonanalytic behavior of a large $N_c$ chiral
perturbation theory calculation of the electric polarizability.


title:
Electroweak and Strong Penguins in B^{\pm, 0}\to \pi\pi, \pi K and KK
  Decays

abstract:
  We calculate CP-violating rates and asymmetry parameters in charged and
neutral $B\to \pi\pi, \pi K$ and $\bar K K$ decays arising from the
interference of tree and penguin (strong and electroweak) amplitudes with
different strong and CKM phases. The perturbative strong (electroweak) phases
develop at order $\alpha_s$ ($\alpha_{em}$) from absorptive parts of one-loop
matrix elements of the next-to-leading (leading) logarithm corrected effective
Hamiltonian. The BSW model is used to estimate the hadronic matrix elements.
Based on this model, we find that the effect of strong phases and penguins is
substantial in most channels, drastic in many. However, a measurement of the
time dependence parameter $a_{\epsilon+\epsilon'}$ in the $\pi^+\pi^-$ channel
is only influenced at the 20\% level by the complication of the penguins.
Recent flavor sum rules developed for $B^{0,\pm} \rightarrow \pi\pi, \pi K, K
\bar K$ amplitudes are tested in this model. Some are well satisfied, others
badly violated, when electroweak penguins are included.


title: Real and Virtual Strange Processes

abstract:
  Following notions of quantum mechanics as interpreted by the Copenhagen
School, we make a distinction between measurements involving one or two virtual
K mesons. New predictions result for the period of K oscillations at the Phi
Factory.


title: The Schwinger Mass in the Massive Schwinger Model

abstract:
  We derive a systematic procedure to compute Green functions for the massive
Schwinger model via a perturbation expansion in the fermion mass. The known
exact solution of the massless Schwinger model is used as a starting point. We
compute the corrections to the Schwinger mass up to second order.


title:
Analytic Approaches to the Evolution of Polarised Parton Distributions
  at Small $x$

abstract:
  The $Q^2$ evolution of polarised parton distributions at small $x$ is
studied. Various analytic approximations are critically discussed. We compare
the full evolution with that obtained from the leading-pole approximation to
the splitting functions, and show that the validity of this approximation
depends critically on the $x \to 0$ behaviour of the starting distributions. A
new analytic solution which is valid at small $x$ is obtained, and its domain
of applicability is discussed.


title: Cosmology of the Next-to-Minimal Supersymmetric Standard Model

abstract:
  We discuss the domain wall problem in the Next-to-Minimal Supersymmetric
Standard Model, with particular attention to the usual solution of explicit
breaking of the discrete symmetry by non-renormalisable operators. This
``solution'' leads to a contradiction between the requirements of cosmology and
those of avoiding the destabilisation of the hierarchy.


title: Higgs Boson Production and Weak Boson Structure

abstract:
  The influence of the QCD structure of the weak bosons on the Higgs boson
production in $e$-$p$ scattering is studied. The energy and Higgs boson mass
dependence of the cross-section, following from the new contributions, is
calculated.


title: String Evolution with Friction

abstract:
  We study the effects of friction on the scaling evolution of string networks
in condensed matter and cosmological contexts. We derive a generalized
`one-scale' model with the string correlation length $L$ and velocity $v$ as
dynamical variables. In non-relativistic systems, we obtain a well-known
$L\propto t^{1/2}$ law, showing that loop production is important. For
electroweak cosmic strings, we show transient damped epoch scaling with
$L\propto t^{5/4}$ (or, in the matter era, $L\propto t^{3/2}$). A low initial
density implies an earlier period with $L\propto t^{1/2}$. For GUT strings, the
approach to linear scaling $L\propto t$ is faster than previously estimated.