title: The evolution of a network of cosmic string loops

abstract:
  We set up and analyse a model for the non-equilibrium evolution of a network
of cosmic strings initially containing only loops and no infinite strings. Due
to this particular initial condition, our analytical approach differs
significantly from existing ones. We describe the average properties of the
network in terms of the distribution function n(l,t) dl, the average number of
loops per unit volume with physical length between l and l + dl at time t. The
dynamical processes which change the length of loops are then estimated and an
equation, which we call the `rate equation', is derived for (dn/dt). In a
non-expanding universe, the loops should reach the equilibrium distribution
predicted by string statistical mechanics. Analysis of the rate equation gives
results consistent with this. We then study the rate equation in an expanding
universe and suggest that three different final states are possible for the
evolving loop network, each of which may well be realised for some initial
conditions. If the initial energy density in loops in the radiation era is low,
then the loops rapidly disappear. For large initial energy densities, we expect
that either infinite strings are formed or that the loops tend towards a
scaling solution in the radiation era and then rapidly disappear in the matter
era. Such a scenario may be relevant given recent work highlighting the
problems with structure formation from the standard cosmic string scenario.


title: Parametric Resonance in Oscillations of Atmospheric Neutrinos?

abstract:
  We consider a solution of the atmospheric neutrino problem based on
oscillations of muon neutrinos to sterile neutrinos: $\nu_{\mu}$
$\leftrightarrow$ $\nu_s$. The zenith angle ($\Theta$) dependences of the
neutrino and upward-going muon fluxes in presence of these oscillations are
studied. The dependences have characteristic form with two dips: at $\cos
\Theta = -0.6 \div -0.2$ and $\cos \Theta = -1.0 \div -0.8$. The latter dip is
due to parametric resonance in oscillations of neutrinos which cross the core
of the earth. A comparison of predictions with data from the MACRO, Baksan and
Super-Kamiokande experiments is given.


title: Kaon Spontaneous CP Violation Reevaluated

abstract:
  The CP parameters $\epsilon$ and $\epsilon'/\epsilon$ are calculated in the
aspon model of spontaneous CP violation, a model which solves the strong CP
problem. A new range for the scale of spontaneous breaking of CP is found. It
is shown that $\epsilon'/\epsilon$ is suppressed by $\sim x^2 v^2/(\kappa^2
\sin^5 \theta_C) \sim 5 \times 10^{-3}$ relative to the Standard Model. If
experiment finds that $\epsilon'/\epsilon$ is $10^{-4}$ or greater in
magnitude, it will mean that the present approach to spontaneous CP violation
is excluded.


title: Effective Field Theory for Low-Energy np Systems

abstract:
  The properties of low-energy neutron-proton systems are studied in an
effective field theory where only nucleons figure as relevant degrees of
freedom. With a finite momentum cut-off regularization scheme, we show that the
large scattering lengths of the np systems do not spoil the convergence of the
effective field theory, which turns out to be extremely successful in
reproducing, with little cut-off dependence, the deuteron properties, the np
1S0 scattering amplitude and most significantly, the M1 transition amplitude
entering into the radiative np capture process.


title:
Measurement of the response of a gallium metal solar neutrino experiment
  to neutrinos from a 51Cr source

abstract:
  The neutrino capture rate measured by the Russian-American Gallium Experiment
is well below that predicted by solar models. To check the response of this
experiment to low-energy neutrinos, a 517 kCi source of 51Cr was produced by
irradiating 512.7 g of 92.4%-enriched 50Cr in a high-flux fast neutron reactor.
This source, which mainly emits monoenergetic 747-keV neutrinos, was placed at
the center of a 13.1 tonne target of liquid gallium and the cross section for
the production of 71Ge by the inverse beta decay reaction was measured to be
(5.55 +/- 0.60 (stat.) +/- 0.32 (syst.)) x 10^(-45) cm^2. The ratio of this
cross section to the theoretical cross section of Bahcall for this reaction is
0.95 +/- 0.12 (exp.) +/- 0.03 (theor.) and to the cross section of Haxton is
0.87 +/- 0.11 (exp.) +/- 0.09 (theor.).
  This good agreement between prediction and observation implies that the
overall experimental efficiency for the solar neutrino measurements is
correctly determined and provides considerable evidence for the reliability of
the solar neutrino measurement.


title: Thouless Energy and Correlations of QCD Dirac Eigenvalues

abstract:
  Eigenvalues and eigenfunctions of the QCD Dirac operator are studied for
gauge field configurations given by a liquid of instantons. We find that for
energy differences $\delta E$ below an energy scale $E_c$ the eigenvalue
correlations are given by Random Matrix Theories with the chiral symmetries of
the QCD partition function. For eigenvalues near zero this energy scale shows a
weak volume dependence that is not consistent with $E_c \sim 1/L^2$ which might
be expected from the pion Compton wavelength and from the behavior of the
Thouless energy in mesoscopic systems. However, the numerical value of $E_c$
for our largest volumes is in rough agreement with estimates from the pion
Compton wavelength. A scaling behaviour consistent with $E_c\sim 1/L^2$ is
found in the bulk of the spectrum. For $\delta E> E_c$ the number variance
shows a linear dependence with a slope which is larger than the nonzero
multifractality index of the wave functions. Finally, the average spectral
density and the scalar susceptibilities are discussed in the context of
quenched chiral perturbation theory. We argue that a nonzero value of the
disconnected scalar susceptibility requires a linear dependence of the number
variance on $\delta E$.


title: CP-odd Phases in Slepton Pair Production

abstract:
  The effects of CP-odd supersymmetric phases on slepton pair production are
considered. It is shown that CP-even observables in $e^+ e^-$ and $e^- e^-$
collisions, such as the total selectron cross section, can depend on CP-odd
supersymmetric phases through interference between different tree level
amplitudes. Left handed selectron pair production in $e^- e^-$ collisions is
particularly sensitive to the relative phase between the bino and wino masses.
This sensitivity is not limited to any kinematic regime and extends over all of
neutralino parameter space. The relative phase between the bino and wino masses
is a renormalization group invariant at one-loop, and as such provides a clean
probe for operators which violate gaugino universality at the messenger scale.


title: Higgs and SUSY Searches at LHC

abstract:
  I start with a brief introduction to Higgs mechanism and supersymmetry. Then
I discuss the theoretical expectations, current limits and search strategies
for Higgs boson(s) at LHC --- first in the SM and then in the MSSM. Finally I
discuss the signatures and search strategies for the superparticles.


title: Testing the Higgs boson gluonic couplings at LHC

abstract:
  We study Higgs + jet production at hadron colliders in order to look for new
physics residual effects possibly described by the $dim=6$ operators
${\O}_{GG}$ and ${\widetilde\O}_{GG}$ which induce anomalous $Hgg$ and $Hggg$
couplings. Two ways for constraining these operators at LHC may be ~useful. The
first is based on the total Higgs boson production rate induced by gluon-gluon
fusion, in which the main cause of limitations are due to theoretical
uncertainties leading to sensitivities of $|d_G|\simeq 3.\times 10^{-4}$ and
$|\widetilde{d}_G|\simeq 1.4\times 10^{-3}$ for the corresponding anomalous
couplings, in the mass range $100 GeV \lsim \mh \lsim 2~00 GeV$. These results
imply sensitivity to new physics scales of 51 and 24 TeV respectively. The
second way investigated here concerns the shape of the Higgs transverse
momentum; for which the theoretical uncertainties are less severe and the
limitations are mainly induced by statistics. A simple analysis, based on the
ratio of the number of events at large and low $p_T$ at LHC, leads to similar
sensitivities, if only the $H\to \gamma \gamma $ decay mode is used. But the
sensitivities can now be improved by a factor 2 to 10, depending on the Higgs
mass, if the Higgs decay modes to $WW^*$, $ZZ^*$, $WW$, $ZZ$ are also used.


title: Charged Current Diffractive Structure Functions

abstract:
  We present our study of the diffraction in charged current DIS. We analyse
the perturbatively tractable excitation of heavy quarks, emphasizing the
peculiarities of the Regge factorization breaking in excitation of open charm.


title: eta_c Production at the Tevatron: A test of NRQCD

abstract:
  We use NRQCD to predict the cross section for $\eta_c$ production at the
Tevatron. The non-perturbative matrix elements required are obtained, using
heavy-quark symmetry, from the matrix elements determined from the CDF $J/\psi$
data. Our numbers are, therefore, predictions of NRQCD and provide a very good
test of it. Even after taking into account the small branching ratio of the
$\eta_c$ into two photons, a substantial rate for the production of this
resonance at the Tevatron is expected.


title: Upgrading of Precision Calculations for Electroweak Observables

abstract:
  A critical assessment is given of the comparison between the new versions of
the programs TOPAZ0 40i and ZFITTER 510. The relevance for precision
calculations around the $\zb$ resonance is briefly discussed. << more
references added >>


title:
CP violation in e+e- -> t tbar: Energy Asymmetries and Optimal
  Observables of b and bbar Quarks

abstract:
  The energy spectra of the b and bbar quarks in e+e- -> t tbar with t -> b W
(tbar -> bbar W) are calculated assuming CP violation in the production
process. Expressions for the corresponding CP violating asymmetries and optimal
observables that determine the imaginary parts of the electric and weak dipole
moment form factors of the top are derived. It is shown that polarization of
the initial lepton beams is essential to disentangle Im d^{\gamma}(s) and Im
d^{Z}(s). Numerical results are given in the Minimal Supersymmetric Standard
Model with complex phases.


title: Sparticle Masses from Kinematic Fitting at a Muon Collider

abstract:
  Three case studies are presented of slepton pair production followed by
two-body or quasi-two-body decays at a muon collider. Precision mass
measurements are possible using a variety of kinematic fitting methods.
Standard Model and supersymmetric backgrounds are easily controlled by
kinematic cuts. In all three cases it appears that detector resolutions, not
backgrounds or statistics, will dominate the final error bars. Polarized beams
are not necessary to control SM backgrounds. However, without polarization it
may be difficult in some cases to disentangle slepton_right from slepton_left
signals.


title:
Perturbative QCD- and Power-Corrected Hadron Spectra and Spectral
  Moments in the Decay $B \to X_s \ell^+ \ell^-$

abstract:
  We compute the leading order (in $\alpha_s$) perturbative QCD and power
($1/m_b^2)$ corrections to the hadronic invariant mass and hadron energy
spectra in the decay $B \to X_s \ell^+ \ell^-$ in standard model. This is done
both by using the heavy quark expansion technique (HQET) and a perturbative-QCD
improved Fermi motion (FM) model which takes into account $B$-meson
wave-function effects. The corrections in the hadron energy ($E_H$) spectrum
are found to be small over a good part of this spectrum in both the methods.
However, the expansion in $1/m_b$ in HQET fails near the lower kinematic
end-point and at the $c\bar{c}$ threshold. The hadronic invariant mass ($S_H$)
spectrum is calculable only over a limited range $S_H > \bar{\Lambda}m_B$ in
the heavy quark expansion, where $\bar{\Lambda} \simeq m_B-m_b$. We also
present results for the first two hadronic moments $< S_H^n>$ and $< E_H^n>$,
$n=1,2$, working out their sensitivity on the HQET and FM model parameters. For
equivalent values of these parameters, the moments in these methods are
remarkably close to each other. Using the FM model, we study the effect of the
experimental cuts, used recently by the CLEO collaboration in searching for the
decay $B \to X_s \ell^+ \ell^-$, on the hadron spectra and hadronic invariant
mass moments. The constraints following from assumed values of $< S_H^n>$ on
the HQET parameters $\lambda_1$ and $\bar{\Lambda}$ are worked out. Data from
the forthcoming B facilities could be used to measure the short-distance
contribution in $B \to X_s \ell^+ \ell^-$ and determine the HQET parameters
$\lambda_1$ and $\bar{\Lambda}$. This could be combined with complementary
constrains in $B \to X \ell \nu_\ell$ to determine them precisely.


title:
Masses, Magnetic Moments, and Semileptonic Decays of Spin 1/2 Baryons
  with Sea Contribution

abstract:
  The spin 1/2 baryons are pictured as a composite system made out of a "core"
of three valence quarks (as in the simple quark model) surrounded by a "sea"
(of gluon and $q\bar{q}$ pairs) which is specified by its total quantum
numbers. We assume the sea is a SU(3) flavor octet with spin 0 or 1 but no
color. This model, considered earlier, is used to obtain simultaneous fits for
masses, magnetic moments and $G_A/G_V$ for semileptonic decays. These fits give
predictions for nucleon spin distributions in reasonable agreement with
experiment.


title: Cyclotron Emissivity in the Early Universe

abstract:
  Primordial magnetic fields present between the eras of neutrino decoupling
and of positron-electron annihilation can lead to the emission of neutrino-anti
neutrino pairs or axions by electrons in excited Landau levels, thereby
changing the electron energy spectrum. The rate is calculated and shown to not
affect significantly the standard Big Bang picture.


title: pi K scattering in effective chiral theory of mesons

abstract:
  In the framework of an effective chiral theory of mesons, pi K scattering is
stydied. The scattering lengths, phase shifts, and cross sections are
calculated. Theoretical results agree well with data. There is no new parameter
in this study.


title:
Dynamical supersymmetry breaking in models with a Green-Schwarz
  mechanism

abstract:
  We consider supersymmetry breaking in theories with gaugino condensation in
the presence of an anomalous U(1) symmetry with anomaly cancellation by the
Green-Schwarz mechanism. In these models, a Fayet-Iliopoulos D-term can give
important contributions to the soft supersymmetry-breaking scalar masses. Most
discussions of this possibility have ignored the dilaton field. We argue that
this is not appropriate in general, and show that the F-term contributions to
the soft breaking terms are comparable to or much larger than the D-term
contributions, depending on how the dilaton is stabilized. We discuss
phenomenological implications of these results.


title: Theoretical status of the B_c meson

abstract: Theoretical predictions on the $B_c$ meson properties are reviewed.


title: t-dependences of vector meson diffractive production in ep collisions

abstract:
  We calculate $p_T$-dependences of diffractive vector meson photo- and
electroproduction in electron-proton collisions with and without proton
dissociation at small momenta transfers. The calculated slopes are in good
agreement with the data.


title: Inelaticity in hadron-nucleus collisions from emulsion chamber studies

abstract:
  The inelasticity of hadron-carbon nucleus collisions in the energy region
exceeding 100 TeV is estimated from the carbon-emulsion chamber data at Pamirs
to be $<K_C> = 0.65\pm 0.08$. When combined with the recently presented data on
hadron-lead nucleus collisions taken at the same energy range it results in the
$K\sim A^{0.086}$ mass number dependence of inelasticity. The evaluated partial
inelasticity for secondary ($\nu > 1$) interactions, $K_{\nu >1} \simeq 0.2$,
suggests that the second and higher interactions of the excited hadron inside
the nucleus proceed with only slight energy losses.


title: Spin effects in heavy quarkonia

abstract:
  A model based on a nonrelativistic potential supplemented by spin dependent
terms of the Breit-Fermi type is described. This model reproduces the known
masses of the $\bar{b}b$ quarkonia within 1MeV and the known masses of the
$\bar{c}c$ quarkonia within 5MeV. Many predictions are made, some of them, e.g.
for the fine splittings of the high $L$ states of the $\bar{b}b$ quarkonia and
of the mass spectrum of the $\bar{b}c$ quarkonia, significantly different from
previous predictions made by other authors.


title: Rapidity gaps and the PHOJET Monte Carlo

abstract:
  A model for the production of large rapidity gaps being implemented in the
Monte Carlo event generator PHOJET is discussed. In this model, high-mass
diffraction dissociation exhibits properties similar to hadron production in
non-diffractive hadronic collisions at high energies. Hard diffraction is
described using leading-order QCD matrix elements together with a parton
distribution function for the pomeron and pomeron-flux factorization. Since
this factorization is imposed on Born graph level only, unitarity corrections
lead to a non-factorizing flux function. Rapidity gaps between jets are
obtained by soft color reconnection. It was previously shown that this model is
able to describe data on diffractive hadron production from the CERN-SPS
collider and from the HERA lepton-proton collider. In this work we focus on the
model predictions for rapidity gap events in p-p collisions at \sqrt{s} = 1800
GeV and compare to TEVATRON data.


title: R-charge Kills Monopoles

abstract:
  Large charge density, unlike high temperature, may lead to nonrestoration of
global and gauge symmetries. Supersymmetric GUTs with the appealing scenario of
unification scale being generated dynamically naturally contain global
continuous $R$ symmetries. We point out that the presence of a large $R$ charge
in the early Universe can lead to GUT symmetry nonrestoration. This provides a
simple way out of the monopole problem.


title:
Two-loop operator matrix elements calculated up to finite terms for
  polarized deep inelastic lepton-hadron scattering

abstract:
  We present the two-loop corrected operator matrix elements contributing to
the scale evolution of the longitudinal spin structure function $g_1(x,Q^2)$
calculated up to finite terms which survive in the limit $\epsilon = N - 4 \to
0$. These terms are needed to renormalize the local operators up to third order
in the strong coupling constant $\alpha_s$. Further the expressions for the
two-loop corrected operator matrix elements can be inserted into one loop
graphs to obtain a part of the third order contributions to these matrix
elements. This work is a first step in obtaining the third order anomalous
dimensions so that a complete next-to-next-to-leading order (NNLO) analysis of
the above mentioned structure function can be carried out. In our calculation
particular attention is paid to the renormalization constant which is needed to
restore the Ward-identities violated by the HVBM prescription for the
$\gamma_5$-matrix in $N$-dimensional regularization.


title:
Comparison of \nu_\mu <-> \nu_\tau and and \nu_\mu <-> \nu_s
  oscillations as solutions of the atmospheric neutrino problem

abstract:
  The simplest explanation for the atmospheric neutrino anomaly is the
transition of muon neutrinos and antineutrinos into states of different flavor.
Data from the reactor experiment Chooz, and the measurement of the energy and
angle distribution of electron--like events in Super--Kamiokande put strong
constraints on $\nu_\mu$--$\nu_e$ mixing, but the transitions $\nu_\mu \to
\nu_\tau$ and $\nu_\mu \to \nu_s$ are viable possibilites. If the muon
neutrinos are mixed with a singlet sterile state, the energy and zenith angle
dependence of the oscillation probability is modified by matter effects, that
are important for $E_\nu/|\Delta m^2| \aprge 10^3$ GeV/eV$^2$. We confront the
theoretical predictions with existing data on contained events and
neutrino--induced upward going muons.


title: Color mixing in high-energy hadron collisions

abstract:
  The color mixing of mesons propagating in a nucleus is studied with the help
of a color-octet Pomeron partner present in the two-gluon model of the Pomeron.
For a simple model with four meson-nucleon channels, color mixings are found to
be absent for pointlike mesons and very small for small mesons. These results
seem to validate the absorption model with two independent color components
used in recent analyses of the nuclear absorption of $J/\psi$ mesons produced
in nuclear reactions.


title: Positive parity pentaquarks in a Goldstone boson exchange model

abstract:
  We study the stability of the pentaquarks uuddQbar, uudsQbar and udssQbar (Q
= c, b, or t) of positive parity in a constituent quark model based on
Goldstone boson exchange interaction between quarks. The pentaquark parity is
the antiquark parity times that of a quark excited to a p-shell. We show that
the Goldstone boson exchange interaction favors these pentaquarks much more
than the negative parity ones of the same flavour content but all quarks in the
ground state. We find that the nonstrange pentaquarks are stable against strong
decays.


title: Nucleon spin structure and mass of quarks

abstract:
  The alternative to the standard formulation of the quark-parton model is
proposed. Our relativistically covariant approach is based on the solution of
the master equations relating the structure and distribution functions, which
consistently takes into account the intrinsic quark motion - in
contradistinction to the standard infinite momentum approach, in which this
motion is latently suppressed. The model well reproduces the experimental data
on the both polarized and unpolarized structure functions, assuming that only
the valence quarks term contributes to the nucleon spin. It is shown, the
combined analysis of the polarized and unpolarized data can give an information
about the effective masses and intrinsic motion of the quarks inside the
nucleon. Simultaneously, it is shown that the rate of the nucleon energy
carried by the quarks can be less, than estimated from the standard approach.
As an addition, a prediction for the proton spin function $g_2$ is given.


title: Spontaneous CP Violation at Finite Temperature in the MSSM

abstract:
  By studying the effective potential of the MSSM at finite temperature, we
find that CP can be spontaneously broken in the intermediate region between the
symmetric and broken phases separated by the bubble wall created at the phase
transition. If CP is violated in this manner, there could be a bubble wall
connecting CP conserving vacua and violating CP halfway, which would result in
sufficient baryon asymmetry of the universe.


title: Parton distributions: a new global analysis

abstract:
  We present a new analysis of parton distributions of the proton. This
incorporates a wide range of new data, an improved treatment of heavy flavours
and a re-examination of prompt photon production. The new set (MRST) shows
systematic differences from previous sets of partons which can be identified
with particular features of the new data and with improvements in the analysis.
We also investigate the sensitivities of the results to (i) the uncertainty in
the determination of the gluon at large x, (ii) the value of alpha_S(M_Z^2) and
(iii) the minimum Q^2 cut on the data that are included in the global fit.


title:
Anomalous dimension of gluonic operator in polarized deep inelastic
  scattering at O(1/N_f)

abstract:
  We compute the O(1/N_f) correction to the predominantly gluonic flavour
singlet twist-2 anomalous dimension used in polarized deep inelastic
scattering. It is consistent with known two loop perturbation theory and we
determine the three loop contribution at O(1/N_f). The treatment of the
epsilon-tensor in the large N_f d-dimensional critical point formalism is also
discussed.


title:
Color Octet Contribution to $J/\psi$ Production at a Photon Linear
  Collider

abstract:
  We investigate $J/\psi$ production at a Photon Linear Collider (PLC) in the
framework of NRQCD factorization approach. It was shown that color octet
contribution is dominating in charmonium production at PLC. The main fraction
of $J/\psi$ comes from the single and double resolved photon processes.
Expected cross sections of charmonium states production are large enough even
at $p_T>5$ GeV to expect several hundreds of $J/\psi$'s through the leptonic
decays channel for a projected integral PLC luminosity of $50 fb^{-1}$}


title: The Small $x$ Behavior of $g_1$ in the Resummed Approach

abstract:
  The double logarithmic terms $\alpha_{s} \ln^{2}x $ are important to predict
precisely the small $x$ behavior of the spin structure function $g_{1}$. We
numerically analyze the evolution of the flavor non-singlet $g_{1}$ including
the all-order resummed effect of these terms. It is pointed out that the
next-to-leading logarithmic corrections produce an unexpectedly large
suppression factor over the experimentally accessible range of $x$ and $Q^{2}$.
This implies that the next-to-leading logarithmic contributions are very
important in order to obtain a definite prediction.


title: Asymmetries in Heavy Meson Production from Light Quark Fragmentation

abstract:
  We discuss the possibility of the asymmetry in $D^-/D^+$ production, from
$\pi^-$ beams, being a direct consequence of the properties of the light quark
fragmentation function into heavy mesons. The main features of the asymmetry,
as a function of $x_F$, are easily described. An integrated sum-rule for the
$D^-, D^+$ difference, is presented. Predictions for the asymmetry, in $B$
meson production, are given.


title: Left-right asymmetries in polarized $e-\mu$ scattering

abstract:
  We consider, in the electroweak standard model context, several left-right
asymmetries in $\mu e$ elastic scattering at fixed target and collider
experiments. For the former case, we show that the muon mass effects are
important in a wide energy range. We also show that these asymmetries are
sensitive to the electroweak mixing angle $\theta_W$. The effect of an extra
$Z'$ neutral vector boson appearing in a 331 model is also considered. The
capabilities of these asymmetries in the search of this extra $Z'$ are
addressed.


title: Imminent Phenomenology of a Minimal Gauge-Mediated Model

abstract:
  We calculate the inclusive branching ratio for B--> X_s gamma, the inclusive
branching ratios and asymmetries for B--> X_s l+ l- and the anomalous magnetic
moment g-2 of the muon, within a minimal gauge-mediated SUSY-breaking model
which naturally generates a large ratio tan(beta) of Higgs field vacuum
expectation values. These predictions are highly correlated with each other,
depending on only two fundamental parameters: the superpartner mass scale and
the logarithm of a common messenger mass. The predictions for B--> X_s gamma
decay and g-2 are in somewhat better agreement with current experiments than
the standard model, but a much sharper comparison will soon be possible using
new measurements now in progress or under analysis. Moreover we predict large
deviations in B--> X_s e+ e- and B--> X_s mu+ mu- asymmetries, and somewhat
smaller ones in B--> X_s e+ e- and B--> X_s tau+ tau- branching ratios, which
will be detectable in hadronic colliders.


title:
Hadronic and elementary multiplicity distributions in a geometrical
  approach

abstract:
  We construct the hadronic multiplicity distribution in terms of an elementary
distribution (at given impact parameter) and the inelastic overlap function
characterized by the observed BEL (Blacker-Edgier-Larger) behaviour. With
suitable parametrizations for the elementary quantities, based on some
geometrical arguments and the most recent data on e+e- annihilation, an
excellent description of pp and p(bar)p inelastic multiplicity distributions at
the highest energies is obtained.


title:
Calculation of the QED Coupling alpha (M_Z) in the Modified
  Minimal-Subtraction Scheme

abstract:
  I calculate the QED coupling, alpha, directly in the MS-bar scheme using an
unsubtracted dispersion relation for the three light quarks, and perturbative
QCD for charm and bottom quarks. Compact analytical expressions are presented,
making this approach particularly suitable for electroweak fits. After
alpha^(-1) (m_tau) = 133.513 +- 0.025 is obtained in a first step, I perform a
4-loop renormalization group evolution with 3-loop matching conditions to
arrive at alpha^(-1) (M_Z) = 127.934 +- 0.026 for alpha_s (M_Z) = 0.120. The
corresponding hadronic contribution to the on-shell coupling is Delta
alpha_had^(5) (M_Z) = 0.02779 +- 0.00019. The error is mainly from m_c, and
from experimental uncertainties in e^+ e^- annihilation into unflavored and
strange hadrons and tau decay data.


title: Bottom Quark Mass from Upsilon Mesons

abstract:
  The bottom quark pole mass $M_b$ is determined using a sum rule which relates
the masses and the electronic decay widths of the $\Upsilon$ mesons to large
$n$ moments of the vacuum polarization function calculated from nonrelativistic
quantum chromodynamics. The complete set of next-to-next-to-leading order (i.e.
${\cal{O}}(\alpha_s^2, \alpha_s v, v^2)$ where $v$ is the bottom quark c.m.
velocity) corrections is calculated and leads to a considerable reduction of
theoretical uncertainties compared to a pure next-to-leading order analysis.
However, the theoretical uncertainties remain much larger than the experimental
ones. For a two parameter fit for $M_b$, and the strong $\bar{{MS}}$ coupling
$\alpha_s$, and using the scanning method to estimate theoretical
uncertainties, the next-to-next-to-leading order analysis yields 4.74 GeV $\le
M_b\le 4.87$ GeV and $0.096 \le \alpha_s(M_z) \le 0.124$ if experimental
uncertainties are included at the 95% confidence level and if two-loop running
for $\alpha_s$ is employed. $M_b$ and $\alpha_s$ have a sizeable positive
correlation. For the running $\bar{{MS}}$ bottom quark mass this leads to 4.09
GeV $\le m_b(M_{\Upsilon(1S)}/2)\le 4.32$ GeV. If $\alpha_s$ is taken as an
input, the result for the bottom quark pole mass reads 4.78 GeV $\le M_b\le
4.98$ GeV (4.08 GeV $\le m_b(M_{\Upsilon(1S)}/2)\le 4.28$ GeV) for $0.114\lsim
\alpha_s(M_z)\le 0.122$. The discrepancies between the results of three
previous analyses on the same subject by Voloshin, Jamin and Pich, and K\"uhn
et al. are clarified. A comprehensive review on the calculation of the heavy
quark-antiquark pair production cross section through a vector current at
next-to-next-to leading order in the nonrelativistic expansion is presented.


title: The Nonlinear Spatial Damping Rate in QGP

abstract:
  The derivative expansion method has been used to solve the semiclassical
kinetic equations of quark-gluon plasma (QGP). The nonlinear spatial damping
rate, the imaginary part of the wave vector, for the longitudinal secondary
color waves in the long wavelength limit has been calculated numerically.


title:
Energy-dependent solar neutrino flux depletion in the Exact Parity Model
  and implications for SNO, SuperKamiokande and BOREXINO

abstract:
  Energy-dependent solar neutrino flux reduction caused by the
Mikheyev-Smirnov-Wolfenstein (MSW) effect is applied to the Exact Parity Model.
Several scenarios are possible, depending on the region of parameter space
chosen. The interplay between intergenerational MSW transitions and vacuum
``intragenerational'' ordinary-mirror neutrino oscillations is discussed.
Expectations for the ratio of charged to neutral current event rates at the
Sudbury Neutrino Observatory (SNO) are estimated. The implications of the
various scenarios for the Boron neutrino energy spectrum and BOREXINO are
briefly discussed. The consequences of MSW-induced solar neutrino depletion
within the Exact Parity Model differ in interesting ways from the standard
$\nu_e - \nu_{\mu, \tau}$ and $\nu_e - \nu_s$ cases. The physical causes of
these differences are determined.


title:
Nonfactorizable Effects in Spectator and Penguin Amplitudes of Hadronic
  Charmless B Decays

abstract:
  Nonfactorizable effects in hadronic charmless B -> PP, VP decays can be
parametrized in terms of the effective number of colors N_c in the effective
parameters $a_i^{eff}$ that are linear combinations of Wilson coefficients. It
is shown that N_c(V+A) in the penguin amplitudes induced by the (V-A)(V+A)
four-quark operators is different from N_c(V-A) in the decay amplitudes arising
from the (V-A)(V-A) operators. Central values of the branching ratios of
$B^\pm\to\omega \pi^\pm$ and $B\to\pi\pi$ decays favor $N_c(V-A)\approx 2$, in
accordance with the nonfactorizable effect observed in $B\to D^{(*)}\pi
(\rho)$. Measurements of the interference effects in $B^-\to\pi^-(\rho^-)\pi^0
(\rho^0)$ decays will provide a more decisive test on the parameter N_c(V-A).
However, $N_c(V+A)\sim 2$ is ruled out by $B^\pm\to\phi K^\pm$ and $B\to\phi
K^*$. We find that N_c(V+A) lies in the range $10\geq N_c(V+A)\geq 4.3$,
subject to the corrections from W-annihilation and space-like penguin effects.
With $N_c(V-A)\approx 2$ we show that the branching ratio of $B\to\eta' K$ is
enhanced considerably at small values of 1/N_c(V+A) so that it is compatible
with experiment. In particular, the measurement of $B^0\to\eta' K^0$ is now
well explained without resorting to any new mechanism or new physics beyond the
Standard Model. Finally, we point out that it is difficult to understand the
observed large branching ratio of $B^\pm\to\omega K^\pm$ within the present
framework. Inelastic final-state interactions may alleviate the difficulty with
this decay mode.


title: New Aspects on a Seesaw Mass Matrix Model

abstract:
  Recent development of the universal seesaw mass matrix model is reviewed. The
model was proposed in order to explain why quark and lepton masses are so small
compared with the electroweak scale \Lambda_L =<\phi_L^0>=174 GeV. However, the
recently observed top-quark mass m_t\simeq 180 GeV seems to make an objection
against the seesaw mass picture. For this problem, it has recently pointed out
that the seesaw mass matrix model is rather favorable to the fact m_t\sim
\Lambda_L if we consider the model with det M_F=0 for up-quark sector, where
M_F is a 3 x 3 mass matrix of hypothetical heavy fermions F. The model can give
a natural explanation why only top-quark acquire the mass of the order of
\Lambda_L. The model with det M_U=0 offers abundant new physics to us (e.g.,
the fourth up-quark t', FCNC, and so on).


title:
B_s --> \gamma \gamma decay in the two Higgs doublet model with flavor
  changing neutral currents

abstract:
  We calculate the leading logarithmic QCD corrections to the decay B_{s}
-->\gamma\gamma in the two Higgs doublet model with tree level flavor changing
currents (model III) including O_7 type long distance effects. Further, we
analyse the dependencies of the branching ratio Br(B_{s} --> \gamma\gamma)$ and
the ratio of CP-even and CP-odd amplitude squares, R=|A^{+}|^2/|A^{-}|^2, on
the charged Higgs mass m_{H^{\pm}} and the selected model III parameters
\xi^{U,D} including the leading logarithmic QCD corrections. It is found that
to look for charged Higgs effects, the measurement of the branching ratio
Br(B_{s} --> \gamma\gamma)$ is promising.


title:
The Promising Process to Distinguish Supersymmetric Models with Large
  tan$\beta$ from the Standard Model: $B\to X_s{\mu}^{+}{\mu}^{-}$

abstract:
  It is shown that in supersymmetric models (SUSYMs) the large supersymmetric
contributions to $B \to X_s{\mu}^{+}{\mu}^{-}$ come from the Feynman diagrams
which consist of exchanging neutral Higgs bosons (NHBs) and the chargino-stop
loop and are proportional to $m_b m_{\mu}$tan$^3\beta/m_{h}^2$ when tan$\beta$
is large and the mass of the lightest neutral Higgs boson m$_h$ is not too
large (say, less than 150 Gev). Numerical results show that the branching
ratios of $B \to X_s{\mu}^{+}{\mu}^{-}$ can be enhanced by more than 100%
compared to the standard model (SM) and the backward-forward asymmetry of
lepton is significantly different from that in SM when tan$\beta \geq 30$.


title: Left-Right SUSY and the Fate of R-Parity

abstract:
  A fresh analysis of Left right symmetric supersymmetric models in the generic
case where the scale of right handed symmetry breaking $M_R >> M_{SUSY}\sim
M_W$ is presented. We conclude that the low energy effective theory for such
models is essentially the MSSM with R parity (and therefore B,L symmetry) but
the spectrum includes heavy conjugate neutrino supermultiplets that permit a
seesaw mechanism and several characteristic charged supermultiplets over and
above those of the MSSM.


title: On the Early Stage of Nucleus--Nucleus Collisions

abstract:
  A statistical model of the early stage of central nucleus--nucleus (A+A)
collisions is developed. We suggest a description of the confined state with
several free parameters fitted to a compilation of A+A data at the AGS. For the
deconfined state a simple Bag model equation of state is assumed. The model
leads to the conclusion that a Quark Gluon Plasma is created in central
nucleus--nucleus collisions at the SPS. This result is in quantitative
agreement with existing SPS data on pion and strangeness production and gives a
natural explanation for their scaling behaviour. The localization and the
properties of the transition region are discussed. It is shown that the
deconfinement transition can be detected by observation of the characteristic
energy dependence of pion and strangeness multiplicities, and by an increase of
the event--by--event fluctuations. An attempt to understand the data on J/psi
production in Pb+Pb collisions at the SPS within the same approach is
presented.


title: Soft Masses in Strong Unification

abstract:
  We examine the infra-red structure of soft supersymmetry breaking masses of
the squarks and sleptons in supersymmetric (SUSY) strong unification schemes
where $\alpha_{GUT}\sim 0.2-1$. We show that combinations of soft masses
approach fixed points which leads to very simple predictions for soft masses at
the intermediate scale. The assumption that the high energy gaugino mass
$M_{1/2}$ dominates over the soft scalar masses leads to a strong suppression
of flavour changing neutral currents, and a low energy SUSY spectrum which is
simply predicted in terms of two parameters, namely $\alpha_{GUT}$ and
$M_{1/2}$. Due to the quickly falling gauge couplings beneath the high energy
scale, the low energy spectrum has a characteristic ``scalar dominated''
signature quite unlike the standard gaugino dominated MSSM where the
right-handed sleptons are predicted to be rather light. We also examine the new
sources of flavour changing expected in such models, and in particular show
that the flavour violation coming from the D-term of a $U(1)_X$ gauged family
symmetry may be reduced to an acceptable level.


title:
Diffractive dijet photoproduction as a probe of the off-diagonal gluon
  distribution

abstract:
  We propose exclusive diffractive dijet photoproduction as an ideal measure of
the off-diagonal gluon distribution at high scales. We solve the off-diagonal
evolution equations for the gluon and quark singlet over the full kinematic
domain. We discuss the nature of the solutions of these equations, which embody
both DGLAP and ERBL evolution. We give predictions for the transverse momentum
distribution of the jets. In particular we quantify the enhancement arising
from the evolution of the off-diagonal parton distributions.


title: See-Sawless Neutrino Masses

abstract:
  An alternative to the famous see-saw mechanism is proposed to explain the
smallness of the neutrino masses (if present). This model involves a fourth
family which mixes very little with the other three. It contains one heavy
neutrino (mN > mZ /2) and three very light neutrinos whose masses are
radiatively induced. In contrast with the see-saw mechanism, all neutrino
masses are Dirac masses. In one particular scenario, the three light neutrinos
are almost degenerate in mass and are found to be consistent with fits to the
Solar and Atmospheric neutrino deficits. They might even account for the Hot
Dark Matter.


title: Extra Spacetime Dimensions and Unification

abstract:
  We study the effects of extra spacetime dimensions at intermediate mass
scales, as expected in string theories with large-radius compactifications, and
focus on the gauge and Yukawa couplings within the Minimal Supersymmetric
Standard Model. We find that extra spacetime dimensions naturally lead to the
appearance of grand unified theories at scales substantially below the usual
GUT scale. Furthermore, we show that extra spacetime dimensions provide a
natural mechanism for explaining the fermion mass hierarchy by permitting the
Yukawa couplings to receive power-law corrections. We also discuss how
proton-decay constraints may be addressed in this scenario, and suggest that
proton-decay amplitudes may be exactly cancelled to all orders in perturbation
theory as a result of new Kaluza-Klein selection rules corresponding to the
extra spacetime dimensions.


title: $g_{ND\Lambda_{c}}$ from QCD Sum Rules

abstract:
  The $ND\Lambda_c$ coupling constant is evaluated in a full QCD sum rule
calculation. We study the Borel sum rule for the three point function of one
pseudoscalar one nucleon and one $\Lambda_c$ current up to order seven in the
operator product expansion. The Borel transform is performed with respect to
the nucleon and $\Lambda_c$ momenta, which are taken to be equal, whereas the
momentum $q^2$ of the pseudoscalar vertex is taken to be zero. This coupling
constant is relevant in the meson cloud description of the nucleon which has
been recently used to explain exotic events observed by the H1 and ZEUS
Collaborations at HERA.


title: Strong Dynamics at the Muon Collider: Working Group Report

abstract:
  New strong dynamics at the energy scale ~ 1 TeV is an attractive and elegant
theoretical ansatz for the origin of electroweak symmetry breaking. We review
here the theoretical models for strong dynamics, particularly, technicolor
theories and their low energy signatures. We emphasize that the fantastic beam
energy resolution (sigma_E/E ~10^{-4}) expected at the first muon collider
(sqrt{s} = 100-500 GeV) allows the possibility of resolving some
extraordinarily narrow technihadron resonances and, Higgs-like techniscalars
produced in the s-channel. Investigating indirect probes for strong dynamics
such as search for muon compositeness, we find that the muon colliders provide
unparallel reaches. A big muon collider (sqrt{s} =3-4 TeV) would be a
remarkable facility to study heavy technicolor particles such as the topcolor
Z', to probe the dynamics underlying fermion masses and mixings and to fully
explore the strongly interacting electroweak sector.


title: Pion-Nucleon coupling at finite temperature

abstract:
  The pion nucleon vertex function at finite temperature is studied in the
framework of: (a) the thermal (linear) sigma model to leading (one-loop) order,
and (b) a thermal QCD-Finite Energy Sum Rule. Results from both methods
indicate that the strength of the pion-nucleon coupling decreases with
increasing T, vanishing at a critical temperature. The associated mean-square
radius is a monotonically increasing function of T, diverging at the critical
temperature. This is interpreted as (analytical) evidence for the quark-gluon
deconfinement phase transition.


title: Do $1^- c \bar c g$ hybrid meson exist, do they mix with charmonium ?

abstract:
  Hybrid $ c \bar c g$ of quantum numbers $1^{--}$ are considered in a quark
model with constituant quarks and gluon. The lowest $J^P=1^-$ states may be
built in two ways, $l_g=1$ (gluon excited) corresponding to an angular momentum
between the gluon and the $c \bar c$ system, while $l_{c\bar c}=1$ (quark
excited) corresponds to an angular momentum between the $c$ and the $\bar c$.
The lowest lying hybrid $J^P=1^-$ state in the flux tube model is similar to
the $l_g=1$ in the quark-gluon model. In particular it verifies the selection
rule that it cannot decay into two fundamental mesons. The $l_{q\bar q}=1$
hybrid may decay into two fundamental mesons, but with decay widths larger than
1 GeV, which tells that they do not really exist as resonant states. Using a
chromoharmonic potential, we find no mixing between the $l_g=1$ and $l_{c\bar
c}=1$. More realistic potentials might induce a strong mixing between them,
implying that no hybrid meson exist. If, on the contrary, such a strong mixing
does not occur, we find, in agreement with the flux tube model, that only the
$l_g=1$ appears as a real resonant state. In such a case, hybrid mesons may
exist as resonances only if they are decoupled from the ground state channels,
which explains the difficulty to observe them experimentally. We reconsider
accordingly the Ono-Close-Page scenario of mixing between charmonium and
charmed-hybrid to explain the anomalies around 4.1 GeV. We find a very small
mixing between radially excited charmonium and hybrid mesons, which forbids
considering the $\psi(4.040)$ and $\psi(4.160)$ as combinations of 3S
charmonium and $l_g=1$ hybrid meson with a large mixing.


title: Flavour transitions of Dirac-Majorana neutrinos

abstract:
  From a phenomenological point of view, we study active-active and
active-sterile flavour-changing (and flavour-conserving) oscillations of
Dirac-Majorana neutrinos both in vacuum and in matter. The general expressions
for the transition probabilities in vacuum are reported. We then investigate
some interesting consequences following from particular simple forms of the
neutrino mass matrices, and for the envisaged scenarios we discuss in detail
neutrino propagation in matter. Special emphasis is given to the problem of
occurrence of resonant enhancement of active-active and active-sterile neutrino
oscillations in a medium. The peculiar novel features related to the
Dirac-Majorana nature of neutrinos are particularly pointed out.


title: The speed of cool soft pions

abstract:
  The speed of cool pions in the chiral limit is analytically computed at low
temperature within the imaginary time formalism to two loop order. This
evaluation shows a logarithmic dependence in the temperature where the scale
within the logarithm is very large compared to the pion decay constant.


title:
Radiative Energy Loss of High Energy Partons Traversing an Expanding QCD
  Plasma

abstract:
  We study analytically the medium-induced energy loss of a high energy parton
passing through a finite size QCD plasma, which is expanding longitudinally
according to Bjorken's model. We extend the BDMPS formalism already applied to
static media to the case of a quark which hits successive layers of matter of
decreasing temperature, and we show that the resulting radiative energy loss
can be as large as 6 times the corresponding one in a static plasma at the
reference temperature $T = T (L)$, which is reached after the quark propagates
a distance $L$.


title: Radiative corrections to the process $\mu^+ \mu^- \to H \gamma$

abstract:
  QED radiative corrections to the cross-section of muon-antimuon annihilation
into Higgs boson and photon are calculated within the 1-loop approximation. We
write down the expression for cross-section in the form of Drell-Yan process,
taking into account higher order leading logs. The non-singlet structure
functions of fermions are shown to obey here evolution equations of twist-3
operators. Numerical estimation shows an importance of the correction in the
region close to the threshold of Higgs production.


title:
Factorization and soft-gluon divergences in isolated-photon cross
  sections

abstract:
  We study the production of isolated photons in $e^+e^-$ annihilation and give
the proof of the all-order factorization of the collinear singularities. These
singularities are absorbed in the standard fragmentation functions of partons
into a photon, while the effects of the isolation are consistently included in
the short-distance cross section. We compute this cross section at order $\as$
and show that it contains large double logarithms of the isolation parameters.
We explain the physical origin of these logarithms and discuss the possibility
to resum them to all orders in $\as$.


title: The MSSM at the low tan beta fixed point is meta-stable

abstract:
  We analyse the mass spectrum of the Constrained Minimal Supersymmetric
Standard Model at the low tan beta fixed point. We find that the model only
satisfies experimental and dark matter bounds in regions where the vacuum is
meta-stable -- ie where it violates `unbounded from below' (UFB) bounds. Adding
a small amount of R-parity violation solves these problems but the absolute
upper bound on the lowest higgs mass m_{h^0}<97 GeV remains. We present the
predicted sparticle mass spectrum as a function of the gluino mass m_g.


title:
Enhanced Electroweak Radiative Corrections in SUSY: Gluon-free
  Observables

abstract:
  Large top quark mass is responsible for the enhancement of the oblique
radiative corrections in SUSY models. We present the analytical formulas for
these corrections to the $W$-boson mass $m_W$ and to $Z$ $l^+ l^-$ coupling
constants. The comparison with the result of the Standard Model fit is made.


title: Finite Temperature Retarded and Advanced Fields

abstract:
  By employing retarded and advanced propagators, Aurenche and Becherrawy
showed how to rewrite the real-time thermal Feynman rules so that the
temperature dependence is removed from the free propagators and transferred to
the vertices. The present paper introduces retarded and advanced field
operators and incorporates all temperature dependence into the interaction term
of the Hamiltonian. Perturbative expansions of the Green functions in the
Hamiltonian formulation give the correct results order by order in perturbation
theory.
  The spectrum of the temperature-dependent Hamiltonian contains the thermal
quasiparticles that produce poles in the propagators.


title: Electroweak Baryogenesis

abstract:
  Contrary to naive cosmological expectations, all evidence suggests that the
universe contains an abundance of matter over antimatter. This article reviews
the currently popular scenario in which testable physics, present in the
standard model of electroweak interactions and its modest extensions, is
responsible for this fundamental cosmological datum. A pedagogical explanation
of the motivations and physics behind electroweak baryogenesis is provided, and
analytical approaches, numerical studies, up to date developments and open
questions in the field are also discussed.


title: Overview of Physics at a Muon Collider

abstract:
  Muon colliders offer special opportunities to discover and study new physics.
With the high intensity source of muons at the front end, orders of magnitude
improvements would be realized in searches for rare muon processes, in deep
inelastic muon and neutrino scattering experiments, and in long-baseline
neutrino oscillation experiments. At a 100 to 500 GeV muon collider, neutral
Higgs boson (or techni-particle) masses, widths and couplings could be
precisely measured via s-channel production. Also, threshold cross-section
studies of W+ W-, t t-bar, Zh and supersymmetric particle pairs would precisely
determine the corrresponding masses and test supersymmetric radiative
corrections. At the high energy frontier a 3 to 4 TeV muon collider is ideally
suited for the study of scalar supersymmetric particles and extra Z-bosons or
strong WW scattering.


title: Less Minimal Supersymmetric Standard Model

abstract:
  Most of the phenomenological studies of supersymmetry have been carried out
using the so-called minimal supergravity scenario, where one assumes a
universal scalar mass, gaugino mass, and trilinear coupling at M_{GUT}. Even
though this is a useful simplifying assumption for phenomenological analyses,
it is rather too restrictive to accommodate a large variety of phenomenological
possibilities. It predicts, among other things, that the lightest
supersymmetric particle (LSP) is an almost pure B-ino, and that the
mu-parameter is larger than the masses of the SU(2)_{L} and U(1)_{Y} gauginos.
We extend the minimal supergravity framework by introducing one extra
parameter: the Fayet--Iliopoulos D-term for the hypercharge U(1), D_Y. Allowing
for this extra parameter, we find a much more diverse phenomenology, where the
LSP is \tilde{\nu}_{\tau}, \tilde{\tau} or a neutralino with a large higgsino
content. We discuss the relevance of the different possibilities to collider
signatures. The same type of extension can be done to models with the gauge
mediation of supersymmetry breaking. We argue that it is not wise to impose
cosmological constraints on the parameter space.


title: On mixing angles and magnetic moment of heavy tau neutrino

abstract:
  If the magnetic moment of unstable tau neutrinos with the mass of $O$(MeV) is
in the region of $10^{-8}\mu_{B} \lesssim \mu_{\nu_{\tau}} \lesssim
10^{-6}\mu_{B}$, it is compatible with the present experimental and
cosmological bounds.
  It is pointed out here, that if the tau neutrino has such a large magnetic
moment and can oscillate into a neutrino of another flavour the results from
$\nu e$ scattering experiment at LAMPF constrain the tau neutrino mixing angles
to $sin^{2}2\theta_{e \tau} \lesssim 2\times 10^{-6} - 2\times 10^{-2}$ and
$sin^{2}2\theta_{\mu\tau} \lesssim 10^{-6} - 10^{-2}$ depending on the magnetic
moment value in the allowed region.


title: Relativistic quantum model of confinement and the current quark masses

abstract:
  We consider a relativistic quantum model of confined massive spinning quarks
and antiquarks which describes leading Regge trajectories of mesons. The quarks
are described by the Dirac equations and the gluon contribution is approximated
by the Nambu-Goto straight-line string. The string tension and the current
quark masses are the main parameters of the model. Additional parameters are
phenomenological constants which approximate nonstring short-range
contributions. Comparison of the measured meson masses with the model
predictions allows one to determine the current quark masses (in MeV) to be
$m_s = 227 \pm 5,~ m_c = 1440 \pm 10,~ m_b = 4715 \pm 20$. The chiral $SU_3$
model[23] makes it possible to estimate from here the $u$- and $d$-quark masses
to be $m_u = 6.2 \pm 0.2$~ Mev and $m_d = 11.1 \pm 0.4$ Mev.


title: Testing 2HDM at Muon Colliders

abstract:
  One very light neutral Higgs scalar with mass, say, below 40-50 GeV is still
allowed in the non-supersymmetric 2HDM (Model II), while the remaining
particles of the Higgs sector in this model have to be heavier. The possibility
of testing such a scenario at Muon Colliders is discussed.


title: Factorization and Effective Theories

abstract:
  We prove factorization in the decay of a B meson into a D* + jet using the
Large Energy Effective Theory.
  The proof is non perturbative, does not require any gauge fixing and is exact
in the limit of a very narrow jet. On the other hand, it is shown that this
theory is unable to consistently describe completely exclusive processes such
as for example a B which decays into a D* + pion, due to an oversimplification
of transverse momentum dynamics.
  Therefore we present a variant of the Large Energy Effective Theory, i.e. a
new effective theory for massless particles which properly takes into account
transverse degrees of freedom and is the natural framework to study exclusive
non-leptonic decays.


title:
Axion Emission by Magnetic-Field Induced Conversion of Longitudinal
  Plasmons

abstract:
  Magnetic fields mix axions with photons, allowing for the cyclotron process e
-> e + a by virtue of an intermediate plasmon even if axions do not couple to
electrons at tree level. The axion and longitudinal-plasmon dispersion
relations always cross for a certain wave number, leading to a resonant
enhancement of this process. Even then, however, it cannot quite compete with
the usual nucleon processes in a supernova core. The well-known axion window
10^{-5} eV < m_a < 10^{-2} eV remains open and axions may still constitute the
cosmic dark matter.


title: Neutrino propagation in AGN environment

abstract:
  Assuming the violation of equivalence principle (VEP) by ultra high energy
AGN neutrinos we study the effect of random magnetic field fluctuation on
conversion of electron neutrinos to tau anti-neutrinos.


title: Atmospheric Muon Flux at Sea Level, Underground, and Underwater

abstract:
  The vertical sea-level muon spectrum at energies above 1 GeV and the
underground/underwater muon intensities at depths up to 18 km w.e. are
calculated. The results are particularly collated with a great body of the
ground-level, underground, and underwater muon data. In the hadron-cascade
calculations, the growth with energy of inelastic cross sections and pion,
kaon, and nucleon generation in pion-nucleus collisions are taken into account.
For evaluating the prompt muon contribution to the muon flux, we apply two
phenomenological approaches to the charm production problem: the recombination
quark-parton model and the quark-gluon string model. To solve the muon
transport equation at large depths of homogeneous medium, a semi-analytical
method is used. The simple fitting formulas describing our numerical results
are given. Our analysis shows that, at depths up to 6-7 km w. e., essentially
all underground data on the muon intensity correlate with each other and with
predicted depth-intensity relation for conventional muons to within 10%.
However, the high-energy sea-level data as well as the data at large depths are
contradictory and cannot be quantitatively decribed by a single nuclear-cascade
model.


title:
Analysis of Lambda_b to Lambda_c Weak Decays in Heavy Quark Effective
  Theory

abstract:
  The Lambda_b to Lambda_c semileptonic decay is analyzed in the framework of
heavy quark effective theory to the order of 1/m_c and 1/m_b. The QCD sum rule
and large N_c predictions to the decay form factors are applied. It argues that
the subleading baryonic Isgur-Wise function in the large N_c limit vanishes.
The decay rates, distributions and asymmetry parameters are calculated
numerically. Some of the nonleptonic decay modes are discussed in the end.


title:
Weak form factors for semileptonic octet baryon decays in the chiral
  quark model

abstract:
  We study the weak vector and axial-vector form factors of first- and
second-class currents for the semileptonic octet baryon decays in the spirit of
the chiral quark model. Our results for the weak magnetism form factors are
consistent with the conserved vector current (CVC) results. The induced
pseudotensor form factors, which are highly model dependent, are small. The
overall performance of the chiral quark model is quite good and in general
agreement with existing experimental data.


title:
Quark Mass Renormalization in the $\MSbar$ and RI schemes up to the NNLO
  order

abstract:
  We compute the relation between the quark mass defined in the minimal
modified $\MSbar$ scheme and the mass defined in the ``Regularization
Invariant" scheme (RI), up to the NNLO order. The RI scheme is conveniently
adopted in lattice QCD calculations of the quark mass, since the relevant
renormalization constants in this scheme can be evaluated in a non-perturbative
way. The NNLO contribution to the conversion factor between the quark mass in
the two schemes is found to be large, typically of the same order of the NLO
correction at a scale $\mu \sim 2$ GeV. We also give the NNLO relation between
the quark mass in the RI scheme and the renormalization group-invariant mass.


title: Neutron Electric Dipole Moment in SUSY SU(5) GUT

abstract:
  The existing estimation of the Electric Dipole Moment(EDM) of the neutron in
the SUSY SU(5) GUT model was quite smaller than one in the MSSM, despite of its
increased degree of freedom. This paradoxical result can be resolved by
appropriately estimating the CP-violation in the Higgs sector. As a result, the
neutron EDM in this model is estimated lager than the existing one as expected.


title: Two-loop QCD corrections of the massive fermion propagator

abstract:
  The off-shell two-loop correction to the massive quark propagator in an
arbitrary covariant gauge is calculated and results for the bare and
renormalized propagator are presented. The calculations were performed by means
of a set of new generalized recurrence relations proposed recently by one of
the authors. From the position of the pole of the renormalized propagator we
obtain the relationship between the pole mass and the \bar{MS} mass. This
relation confirms the known result by Gray et al.. The bare amplitudes are
given for an arbitrary gauge group and for arbitrary space-time dimensions.


title: Optimized delta-Expansion in QCD; a challenge

abstract:
  We split the Yang-Mills Lagrangian into a free and an interaction part in
such a way, that the free part is non-local and contains an arbitrary form
factor.
  Manifest gauge invariance is guaranteed by connecting the field-strength
tensors at different space-time points by a string. As a result the gluon
propagator, which, due to the presence of the string, now contains many
different contributions, comes out strictly transversal in one-loop order.
  We also calculate the ghost self-energy and the ghost-gluon vertex in
one-loop order. Subsequently we discuss how one can determine the "optimal"
form of the form factor. To apply well known principles like "fastest apparent
convergence" or "principle of minimal sensitivity" one has first to solve some
problems connected with divergences and renormalization. Here we concentrate on
the calculation of the anomalous dimensions and the beta-function. This is
technically simpler because only the divergent contributions of the integrals
have to be determined. The beta-function becomes independent of the gauge
parameter as it should. A puzzle with respect to the principle of minimal
sensitivity shows up. Really interesting non-perturbative results are expected
when applying the above principles directly to the propagator. For the
beta-function a two loop calculation would be required to obtain non-trivial
results.


title: Nuclear effects in QCD

abstract:
  Production of Drell-Yan pairs and open and hidden heavy flavor on nuclear
targets is examined within perturbative QCD. The effects of modifications of
nucleon structure functions inside the nuclear medium are considered. Besides,
nuclear dependence of charmonium and bottonium absorption is studied in the
framework of the Glauber-Gribov model. The low energy limit of this approach
recovers the probabilistic formula usually employed for charmonium and
bottonium suppression in nuclear collisions.


title: A model for the parton distributions in hadrons

abstract:
  A simple model is presented for the parton distributions in hadrons. The
parton momenta in the hadron rest frame are derived from a spherically
symmetric, Gaussian, distribution having a width motivated by the Heisenberg
uncertainty relation applied to the hadron size. Valence quarks and gluons
originate from the `bare' hadron, while sea partons arise mainly from pions in
hadronic fluctuations. Starting from a low Q^2 scale, the distributions are
evolved with next-to-leading order DGLAP and give the proton structure function
F2(x,Q^2) in good agreement with deep inelastic scattering data.


title: An Analysis of Diffraction in Deep-Inelastic Scattering

abstract:
  We propose a simple parametrization for the deep-inelastic diffractive cross
section. It contains the contribution of $q\bar{q}$ production to both the
longitudinal and the transverse diffractive structure functions, and of the
production of $q\bar{q}g$ final states from transverse photons. We start from
the hard region and perform a suitable extrapolation into the soft region. We
test our model on the 1994 ZEUS and H1 data, and confront it with the H1
conjecture of a singular gluon distribution.


title: Field Evolution leading to hybrid inflation

abstract:
  In general the onset of hybrid inflation requires an extremely homogeneous
field configuration at the end of Planck era. The field \phi orthogonal to the
inflaton \sigma must be zero with high accuracy over the range exceeding the
initial horizon size \sim m_{Pl}^{-1} by about two orders of magnitude. We
consider a supersymmetric model that permits the decay of the oscillating field
\phi into light particles. We study the field evolution and find that the
requirement of the extreme homogeneity can be relaxed. However, the field \phi
must still be smaller than the inflaton by a factor of order 1 over a region
far exceeding the initial horizon size.


title:
A model independent and rephase invariant parametrization of CP
  violation

abstract:
  The phenomenological description of the neutral B meson system is proposed in
terms of the fundamental CP-violating observables and within a rephasing
invariant formalism. This generic formalism can select the time-dependent and
time-integrated asymmetries which provide the basic tools to discriminate the
different kinds of possible CP-violating effects in dedicated experimental
B-meson facilities.


title:
Limiting SUSY-QCD spectrum and its application for decays of superheavy
  particles

abstract:
  The supersymmetric generalization of the limiting and Gaussian QCD spectra is
obtained. These spectra are valid for $x \ll 1$, when the main contribution to
the parton cascade is given by gluons and gluinos. The derived spectra are
applied to decaying superheavy particles with masses up to the GUT scale. These
particles can be relics from the Big Bang or produced by topological defects
and could give rise to the observed ultrahigh energy cosmic rays. General
formulae for the fluxes of protons, photons and neutrinos due to decays of
superheavy particles are obtained.


title: B decays into light mesons

abstract:
  I calculate the form factors describing semileptonic and penguin induced
decays of B mesons into light pseudoscalar and vector mesons. The form factors
are calculated from QCD sum rules on the light-cone including contributions up
to twist 4, radiative corrections to the leading twist contribution and SU(3)
breaking effects. The theoretical uncertainty is estimated to be $\sim$
(15-20)%.


title: A new order $\alpha$ correction to the decay rate of pionium

abstract:
  Recently, much work has been devoted to the calculation of order $\alpha$
corrections to the decay rate of pionium, the $\pi^+ \pi^-$ bound state. In
previous calculations, nonrelativistic QED corrections were neglected since
they start at order $\alpha^2$ in hydrogen and positronium. In this note, we
point out that there is one correction which is actually of order $\alpha$
times a function of the ratio $\mu_r \alpha / m_e$, where $\mu_r$ is the
reduced mass of the system. When $\mu_r \alpha \ll m_e$, this function can be
Taylor expanded and leads to higher order corrections. When $\mu_r \alpha
\approx m_e$, as is the case in pionium, the function is of order one and the
correction is of order $\alpha$. We use an effective field theory approach to
calculate this correction and find it equal to $0.4298 \alpha \Gamma_0$. We
also calculate the corresponding correction to the dimuonium ($\mu^+ \mu^-$
bound state) decay rate and obtained a result in agreement with Jentschura et
al.


title:
Soft-Particle Spectra as a Probe of Interconnection Effects in Hadronic
  W^+ W^- Events

abstract:
  Cross-talk between the W^+ and W^- sources of hadron production at LEP2
offers a hope to learn about basic properties of QCD, but at the same time
threatens high-precision measurements of the W boson mass. Directly visible
effects are not expected to be large, however. It is, therefore, important to
develop methods to measure the level of interconnection in the data ---
`connectometers'. In this article we study one particular set of observables,
namely the reduced rate of low-momentum particle production caused by
reconnection. In realistic scenarios the expected signals are at the border of
visibility, but not quite beyond reach. Special studies on kaons and protons,
or with other subsets of the data, could provide supporting evidence. We also
show how LEP1 Z$^0$ events could be used to define an alternative reference
sample.


title:
The Chern-Simons number as an order parameter : classical sphaleron
  transitions for SU(2)-Higgs field theories for a Higgs mass approximately
  equal to 120 GeV

abstract:
  The classical transitions between topologically distinct vacua in a
SU(2)-Higgs model, using a Higgs field of mass approximately 120 GeV, is
examined to probe the crossover region between the symmetric and broken phase.
Assuming the Higgs mass is constant, we find the width of this crossover region
is approximately 20% of the average temperature. We suggest that this
observable is a better parameter to explore this region of phase space than
equal-time correlation functions.


title: Perturbative QCD with string tension

abstract:
  String tension is introduced in perturbative QCD without hindering ultra
violet renormalizability . The running gauge coupling constant remains
unaltered and the string tension in the high energy limit vanishes
asymptotically. Using 1/N techinique the theory can be explicitly analytically
computable with cofinement built in . Spontaneous chiral symmetry breakdown
along with its Goldstone is exhibited.


title: Preheating the universe in hybrid inflation

abstract:
  One of the fundamental problems of modern cosmology is to explain the origin
of all the matter and radiation in the Universe today. The inflationary model
predicts that the oscillations of the scalar field at the end of inflation will
convert the coherent energy density of the inflaton into a large number of
particles, responsible for the present entropy of the Universe. The transition
from the inflationary era to the radiation era was originally called reheating,
and we now understand that it may consist of three different stages:
preheating, in which the homogeneous inflaton field decays coherently into
bosonic waves (scalars and/or vectors) with large occupation numbers;
backreaction and rescattering, in which different energy bands get mixed; and
finally decoherence and thermalization, in which those waves break up into
particles that thermalize and acquire a black body spectrum at a certain
temperature. These three stages are non-perturbative, non-linear and out of
equilibrium, and we are just beginning to understand them. In this talk I will
concentrate on the preheating part, putting emphasis on the differences between
preheating in chaotic and in hybrid inflation.


title: A Re-examination of Quenches in $^{4}$He

abstract:
  In the light of recent difficulties in observing vortices in quenches of
liquid $^{4}$He to its superfluid state we re-examine the Zurek scenario for
their production. We find that the standard prediction is suspect because of a
confusion over correlation lengths.


title: The Supercritical Pomeron in QCD

abstract:
  Deep-inelastic diffractive scaling violations have provided fundamental
insight into the QCD pomeron, suggesting a single gluon inner structure rather
than that of a perturbative two-gluon bound state. This talk outlines a
derivation of a high-energy, transverse momentum cut-off, confining solution of
QCD. The pomeron, in first approximation, is a single reggeized gluon plus a
``wee parton'' component that compensates for the color and particle properties
of the gluon. This solution corresponds to a supercritical phase of Reggeon
Field Theory.


title: Phenomenology of stops, sbottoms, staus and tau-sneutrino

abstract:
  We discuss the phenomenology of third generation sfermions paying particular
attention to the implications of the Yukawa couplings and to the left-right
mixing. Analytical formulae are given for the sfermion mixing, the production
cross sections at e+e- colliders, and for all possible two body decay widths
that can occur at tree level. In case of the light stop stop we give in
addition the analytical formulae for the most important three body decay
widths. We give detailed numerical discussion of the various production cross
sections at LEP2 and a future e+e- Linear Collider. We discuss the various
decay channels paying particular attention on the decays into Higgs and vector
bosons, and on the three body decays of the light stop.


title: Meson-Meson interaction in a non-perturbative chiral approach

abstract:
  A non-perturbative method which combines constraints from chiral symmetry
breaking and coupled channel unitarity is used to describe the meson-meson
interaction up to about 1.2 GeV. The approach uses the O(p^2) and O(p^4) chiral
Lagrangians. The seven free parameters of the O(p^4) Lagrangian are fitted to
the data. The results are in good agreement with a vast amount of experimental
analyses. The amplitudes develop poles in the complex plane corresponding to
the f0, a0, rho, K*, phi, sigma and kappa resonances; the latter two, very
broad. The total and partial decay widths of the resonances are also well
reproduced. Further extensions and applications of this chiral non-perturbative
scheme are also discussed.


title: Quartic Gauge Boson Couplings

abstract:
  We review the recent progress in studying the anomalous electroweak quartic
gauge boson couplings (QGBCs) at the LHC and the next generation high energy
e+-e- linear colliders (LCs). The main focus is put onto the strong electroweak
symmetry breaking scenario in which the non-decoupling guarantees sizable new
physics effects for the QGBCs. After commenting upon the current low energy
indirect bounds and summarizing the theoretical patterns of QGBCs predicted by
the typical resonance/non-resonance models, we review our systematic
model-independent analysis on bounding them via WW-fusion and
WWZ/ZZZ-production. The interplay of the two production mechanisms and the
important role of the beam-polarization at the LCs are emphasized. The same
physics may be similarly and better studied at a multi-TeV muon collider with
high luminosity.


title:
TOPAZ0 4.0 - A new version of a computer program for evaluation of
  de-convoluted and realistic observables at LEP 1 and LEP 2

abstract:
  The program TOPAZ0 was developed for computing a variety of physical
observables which are related to the e+e- annihilation into fermion pairs and
to the large angle Bhabha scattering around the Z resonance. Among them, the Z
parameters or pseudo-observables, the de-convoluted cross sections and those
dressed with QED radiation, and finally the forward-backward asymmetries. The
calculations are performed both for a completely inclusive experimental set-up
and for a realistic one, i.e. a set-up with cuts on the acollinearity angle, on
the energy of the outgoing fermions or on their invariant mass and angular
acceptance. The new version, 4.0, includes several innovative features. First
of all, the most important new capabilities since previous versions are
recently computed electroweak and QCD correction factors that are relevant at
the Z resonance in the light of the present experimental accuracy. Among them,
the effect of the next-to-leading O(alpha^2 m_t^2) corrections and those
radiative corrections to the hadronic decay of the Z which provide complete
corrections of O(alpha alpha_s) to Gamma(Z --> q\bar{q}) with q=u,d,s,c and b.
Secondly, the program has been upgraded to cover two-fermion final states at
LEP 2 energies, where some of the assumptions made for earlier versions are no
longer valid. In particular, to this aim all the electroweak radiative
corrections that are negligible at the Z peak, but relevant far from it, have
been added for s-channel processes, e.g. purely weak boxes, next-to-leading
O(alpha^2) and leading O(alpha^3) QED corrections.


title:
Medium-induced radiative energy loss; equivalence between the BDMPS and
  Zakharov formalisms

abstract:
  We extend the BDMPS formalism for calculating radiative energy loss to the
case when the radiated gluon carries a finite fraction of the quark momentum.
Some virtual terms, previously overlooked, are now included. The equivalence
between the formalism of BDMPS and that of B.Zakharov is explicitly
demonstrated.


title: Radiative corrections to the background of $\mu\to e\gamma$ decay

abstract:
  Radiative muon decay in the kinematics similar to the neutrinoless decay
$\mu\to e\gamma$ is considered. Radiative corrections due to 1-loop virtual
photons and emission of additional soft or hard photons are taken into account.
Analytical expressions and numerical estimations are presented.


title: D-term Inflation in Superstring Theories

abstract:
  An inflationary stage dominated by a $D$-term avoids the slow-roll problem of
inflation in supergravity and may emerge in theories with a non-anomalous or
anomalous U(1) gauge symmetry. The most intriguing and commonly invoked
possibility is that the Fayet-Iliopoulos $D$-term triggering inflation is the
one emerging in superstring theories. We discuss the complications one has to
face when trying to build up a successful $D$-term inflationary scenario in
superstring models. In particular, we show that the ``vacuum shifting''
phenomenon of string theories is usually very efficient even in the early
Universe, thus preventing inflation from taking place. On the other hand, when
$D$-term inflation is free to occur, the presence of a plethora of fields and
several non-anomalous additional abelian symmetries in string theories may help
in reconciling the value of the Fayet-Iliopoulos $D$-term required by the COBE
normalization with the value predicted by string theories. We also show that in
superstring $D$-term inflation gravitinos are likely to pose no cosmological
problem.


title:
Two-loop QCD corrections to semileptonic b decays at an intermediate
  recoil

abstract:
  We present complete O(alpha_s^2) corrections to the decay b-->c+l+nu at the
point where the invariant mass of the leptons sqrt{q^2} equals the c quark
mass. We use this result, together with previously obtained corrections at the
ends of the q^2 spectrum, to estimate the total width of the semileptonic b-->c
decay with O(alpha_s^2) accuracy, essential for the |V_{cb}| determination.


title: Physics at e^- e^-: a Case for Multi-channel Studies

abstract:
  I argue that it would be crucial to have as many channels as possible to
understand the physics of electroweak symmetry breaking (EWSB) in
next-generation collider experiments. A historic example of the parity
violation and the $V-A$ interaction is used to make this point. An e^- e^-
option offers us a new channel in this respect. The usefulness of this channel
is exemplified for the case of supersymmetry and of the strongly coupled EWSB
sector.


title: Small-x Parton Distributions of Large Hadronic Targets

abstract:
  A simple and intuitive calculation, based on the semiclassical approximation,
demonstrates how the large size of a hadronic target introduces a new
perturbative scale into the process of small-x deep inelastic scattering. The
above calculation, which is performed in the target rest frame, is compared to
the McLerran-Venugopalan model for scattering off large nuclei, which has first
highlighted this effect in the infinite momentum frame. It is shown that the
two approaches, i.e., the rest frame based semiclassical calculation and the
infinite momentum frame based McLerran-Venugopalan approach are quantitatively
consistent.


title: Pentaquark Update After Ten Years

abstract:
  Studying scattering of heavy flavor hadrons and looking for bound states is
shown to give experimental information otherwise unobtainable about effective
two-body interactions between constituent $(qq)_6$ and $(\bar qq)_8$ pairs
respectively in color sextet and color octet states. All the successes of the
constituent quark model in $(uds)$ hadron spectroscopy are shown to depend only
on effective two-body interactions in color $3^*$ and singlet states. New
directions for bound pentaquark searches are discussed following the
availability of vertex detectors which can pinpoint events where a proton is
emitted from a secondary vertex. Any such event indicates a particle decaying
weakly by proton emission and the discovery of a new particle if its mass is
higher than that of known charmed baryons. There is no combinatorial background
and striking decay signatures like $p \phi \pi^-$ are no longer needed. The
beauty pentaquark ($\bar b suud$) and the doubly-strange pentaquark ($\bar c
ssud$) may be relevant to future searches. A simple calculation shows that the
effects of flavor-SU(3) breaking on their binding relative to the relevant
thresholds are similar to that for the singly-strange pentaquark ($\bar c
suud$) relative to the $D_s p$ threshold.


title: Heavy Hybrids with Constituent Gluons

abstract:
  Hybrid meson energies are calculated in the static quark limit with the
Dynamical Quark Model (DQM). In the DQM, transverse gluons are represented as
effective constituents with a dynamically generated mass. Hybrid masses are
determined within the Tamm-Dancoff approximation for the resulting relativistic
Salpeter equation. Although the general features of the adiabatic potential
surfaces correspond with lattice data, the results disagree on level orderings.
Similar problems appear to exist in all constituent glue models of hybrids. We
conclude that constituent gluons do not accurately represent soft gluonic
degrees of freedom. The steps necessary to correct this deficiency are
discussed.


title:
Gauge Independence and Relativistic Electron Dispersion Equation in
  Dense Media

abstract:
  We discuss the gauge parameter dependence of particle spectra in statistical
quantum electrodynamics and conclude that the electron spectrum is
gauge-parameter dependent. The physical spectrum being obtained in the Landau
gauge, which leads to gauge invariance in a restricted class of gauge
transformations.


title: Possibility of spontaneous parity violation in hot QCD

abstract:
  We suggest that for QCD in the limit of a large number of colors, N, the
axial U(1) symmetry of massless quarks is effectively restored at the
deconfining=chiral phase transition. If the deconfining transition is of second
order, then the chiral transition is weakly first order. In this case,
metastable states in which parity is spontaneously broken appear at
temperatures below the phase transition. The production of these metastable
states would have dramatic signatures, including enhanced production of eta and
eta' mesons, which can decay through parity violating decay processes such as
eta -> pi^0 pi^0, and global parity odd asymmetries for charged pions. Using a
nonlinear sigma model, in QCD these metastable states only appear rather near
the phase transition.


title:
Procedure for direct measurement of the Cabibbo-Kobayashi-Maskawa angle
  $\gamma$

abstract:
  A natural procedure is presented to measure the angle $\gamma$ from the decay
$B^{\pm} \to \pi^{\pm}\pi^+\pi^-$. It is based in the Dalitz plot fitting
analysis. Neither amplitudes nor strong phases have to be known a priori. We
present simulations of this decay computing both statistical and theoretical
uncertainties and analyze the experimental feasibility. We found that $\gamma$
could be measured with a combined error of the order of 20$^o$ with 90% of CL
after about a couple of years of running of the first generation of B
factories.


title:
Constraints for hypothetical interactions from a recent demonstration of
  the Casimir force and some possible improvements

abstract:
  The Casimir force is calculated in the configuration of a spherical lens and
a disc of finite radius covered by $Cu$ and $Au$ thin layers which was used in
a recent experiment. The correction to the Casimir force due to finiteness of
the disc radius is shown to be negligible. Also the corrections are discussed
due to the finite conductivity, large-scale and short-scale deviations from the
perfect shape of the bounding surfaces and the temperature correction. They
were found to be essential when confronting the theoretical results with
experimental data. Both Yukawa-type and power-law hypothetical forces are
computed which may act in the configuration under consideration due to the
exchange of light and/or massless elementary particles between the atoms of the
lens and the disc. New constraints on the constants of these forces are
determined which follow from the fact that they were not observed within the
limits of experimental errors. For Yukawa-type forces the new constraints are
up to 30 times stronger than the best ones known up today. A possible
improvement of experimental parameters is proposed which gives the possibility
to strengthen constraints on Yukawa-type interactions up to $10^4$ times and on
power-law interactions up to several hundred times.


title: Bremsstrahlung and photon production in thermal QCD

abstract:
  In this paper, we extend the study of bremsstrahlung photon production in a
quark-gluon plasma to the cases of soft static photons and hard real photons.
The general framework of this study is the effective perturbative expansion
based on the resummation of hard thermal loops. Despite the fact that
bremsstrahlung only comes at two loops, we find that in both cases it generates
contributions of the same order of magnitude as those already calculated by
several other groups at one loop. Furthermore, a new process contained in the
two-loop diagrams dominate the emission of a very hard real photon. In all
cases, the rate of real or virtual photon production in the plasma is
appreciably increased compared to the one-loop predictions.


title: Astrophysical constraints on superlight gravitinos

abstract:
  I review the constraints on the mass of gravitinos that follow from
considerations on energy loss in stars and from Big Bang Nucleosynthesis
arguments.


title: Eliminating the low-mass axigluon window

abstract:
  Using recent collider data, especially on the hadronic width the Z0, we
exclude axigluons in the currently allowed low-mass window, namely axigluons in
the mass range 50 GeV < M_A < 120 GeV. Combined with hadron collider data from
di-jet production, axigluons with masses below roughly 1 TeV are now completely
excluded.


title: Quarkonia and the Pole Mass

abstract:
  The pole mass of a heavy quark is ambiguous by an amount of order
$\Lambda_{QCD}$. We show that the heavy-quark potential, $V(r)$, is similarly
ambiguous, but that the total static energy, $2M_{pole}+V(r)$, is unambiguous
when expressed in terms of a short-distance mass. This implies that the
extraction of a short-distance mass from the quarkonium spectrum is free of an
ambiguity of order $\Lambda_{QCD}$, in contrast with the pole mass.


title: Adjoint Messengers and Perturbative Unification at the String Scale

abstract:
  We consider states in the adjoint representation of the Standard Model gauge
group as messengers for mediation of supersymmetry (SUSY) breaking. These new
messengers can shift the gauge coupling unification to the string scale at
O(5x10^{17} GeV) if their masses are at O(10^{14} GeV). The predicted SUSY mass
spectrum at the electroweak scale is significantly different from those in
other gauge-mediated or supergravity models, resulting in robust mass
relations. The gravitino mass is predicted to be about 1-10 GeV. The heavy
messenger sector could provide a superheavy dark matter candidate.


title: Improved Mass Constraints in the MSSM from Vacuum Stability

abstract:
  Using a simple numerical method, we compute the stability of the MSSM vacuum
with respect to tunneling. The stability criterion is then used to put
restrictions on the mass parameters. These restrictions are necessary
conditions for the vacuum stability and compliment the existing sufficiency
conditions obtained analytically.


title: Bound on the neutrino magnetic moment from chirality flip in supernovae

abstract:
  For neutrinos with a magnetic moment, we show that the collisions in a hot
and dense plasma act as an efficient mechanism for the conversion of $\nu_L$
into $\nu_R$. The production rate for right-handed neutrinos is computed in
terms of a resummed photon propagator which consistently incorporates the
background effects. Assuming that the entire energy in a supernova collapse is
not carried away by the $\nu_R$, our results can be used to place an upper
limit on the neutrino magnetic moment $\mu_\nu < (0.1-0.4)\times 10^{-11}\mu_B$


title: Particle Dark Matter Physics: An Update

abstract:
  This write--up gives a rather elementary introduction into particle physics
aspects of the cosmological Dark Matter puzzle. A fairly comprehensive list of
possible candidates is given; in each case the production mechanism and
possible ways to detect them (if any) are described. I then describe detection
of the in my view most promising candidates, weakly interacting massive
particles or WIMPs, in slightly more detail. The main emphasis will be on
recent developments.


title: Z' and anomalous gauge coupling effects at LEP2 and their separation

abstract:
  In the case of the process $e^+e^-\to\mu^+\mu^-$, we study the sensitivity to
either $Z^\prime$ or anomalous gauge coupling effects of two new observables,
$\sigma_+$ and $\sigma_-$, conveniently defined for such kind of analysis. We
discuss general properties of the deviations of these observables from the
Standard Model predictions, and derive the model-independent bounds on the
relevant parameters allowed by present and foreseeable LEP2 data. We also
discuss the possibility of separating the two kinds of effect.


title:
Color Superconductivity and Chiral Symmetry Restoration at Nonzero
  Baryon Density and Temperature

abstract:
  We explore the phase diagram of strongly interacting matter as a function of
temperature and baryon number density, using a class of models for two-flavor
QCD in which the interaction between quarks is modelled by that induced by
instantons. Our treatment allows us to investigate the possible simultaneous
formation of condensates in the conventional quark--anti-quark channel
(breaking chiral symmetry) and in a quark--quark channel leading to color
superconductivity: the spontaneous breaking of color symmetry via the formation
of quark Cooper pairs. At low temperatures, chiral symmetry restoration occurs
via a first order transition between a phase with low (or zero) baryon density
and a high density color superconducting phase. We find color superconductivity
in the high density phase for temperatures less than of order tens to 100 MeV,
and find coexisting $<qq>$ and $<\bar q q>$ condensates in this phase in the
presence of a current quark mass. At high temperatures, the chiral phase
transition is second order in the chiral limit and is a smooth crossover for
nonzero current quark mass. A tricritical point separates the first order
transition at high densities from the second order transition at high
temperatures. In the presence of a current quark mass this tricritical point
becomes a second order phase transition with Ising model exponents, suggesting
that a long correlation length may develop in heavy ion collisions in which the
phase transition is traversed at the appropriate density.


title: Jet broadening in deeply inelastic scattering

abstract:
  In deeply inelastic lepton-nucleus scattering (DIS), the average jet
transverse momentum is broadened because of the multiple scattering in the
nuclear medium. The size of jet broadening is proportional to the multi-parton
correlation functions inside nuclei. We show that at leading order, jet
broadening in DIS and nulcear enhancement in di-jet momentum imbalance and
Drell-Yan $< q_T^2 > $ share the same four-parton correlation functions. We
argue that jet broadening in DIS provide an indenpendent measurement of the
four-parton correlation functions and a test of QCD treatment of multiple
scattering.


title: Gauge unification and the supersymmetric light Higgs mass

abstract:
  We consider general supersymmetric models with: a) arbitrary matter content;
and, b) gauge coupling Unification near the String scale $\sim 10^{17}$ GeV,
and derive the absolute upper limit on the mass of the lightest Higgs boson.
For a top-quark mass $M_t$= 175 GeV, and depending on the supersymmetric
parameter $\tan\beta$, this mass bound can be as high as $\sim$ 200 GeV.


title: New Perspectives in String Phenomenology from Dualities

abstract:
  After a review of some topics concerning the phenomenological applications of
perturbative string theory, I discuss to what extent all of it is affected by
the recent developements in string dualities.


title: Thermodynamics of Non-Topological Solitons

abstract:
  In theories with low energy supersymmetry breaking, the effective potential
for squarks and sleptons has generically nearly flat directions, V(phi) ~ M^4
(log(phi/M))^n. This guarantees the existence of stable non-topological
solitons, Q-balls, that carry large baryon number, B >> (M/m_p)^4, where m_p is
the proton mass. We study the behaviour of these objects in a high temperature
plasma. We show that in an infinitely extended system with a finite density of
the baryon charge, the equilibrium state is not homogeneous and contains
Q-balls at any temperature. In a system with a finite volume, Q-balls evaporate
at a volume dependent temperature. In the cosmological context, we formulate
the conditions under which Q-balls, produced in the Early Universe, survive
till the present time. Finally, we estimate the baryon to cold dark matter
ratio in a cosmological scenario in which Q-balls are responsible for both the
net baryon number of the Universe and its dark matter. We find out naturally
the correct orders of magnitude for M ~ 1...10 TeV: \eta ~ 10^{-10}
(M/TeV)^{-2} (B/10^{26})^{-1/2}.


title:
Nucleon spin content and axial coupling constants in QCD sum rules
  approach

abstract:
  The review of current experimental situation in the measurements of the first
moment $\Gamma_{p,n}$ of spin dependent nucleon structure functions
$g_{1;p,n}(x,Q^2)$ is presented. The results of the calculations of twist-4
corrections to $\Gamma_{p,n}$ are discussed and their accuracy is estimated.
The part of the proton spin $\Sigma$ carried by $u, d, s$ quarks is calculated
in the framework of the QCD sum rules in the external fields. The operators up
to dimension 9 are accounted. An important contribution comes from the operator
of dimension 3, which in the limit of massless $u, d, s$ quarks is equal to the
derivative of QCD topological susceptibility $\chi' (0)$. The comparison with
the experimental data on $\Sigma$ gives $\chi'(0)= (2.3 \pm 0.6) \times 10^{-3}
GeV^2$. The limits on $\Sigma$ and $\chi'(0)$ are found from selfconsistency of
the sum rule, $\Sigma \ga 0.05, \chi' (0) \ga 1.6 \times 10^{-3} GeV^2$. The
values of $g_A = 1.37 \pm 0.10$ and $g^8_A = 0.65 \pm 0.15$ are also determined
from the corresponding sum rules.


title:
Interpretation and resolution of pinch singularities in non-equilibrium
  quantum field theory

abstract:
  Ill-defined pinch singularities arising in a perturbative expansion in out of
equilibrium quantum field theory have a natural analogue to standard scattering
theory. We explicitly demonstrate that the occurrence of such terms is directly
related to Fermi's golden rule known from elementary scattering theory and is
thus of no mystery. We further argue that within the process of thermalization
of a plasma one has to resum such contributions to all orders as the process
itself is of non-perturbative nature. In this way the resummed propagators
obtain a finite width. Within the Markov approximation of kinetic theory the
actual phase space distribution at a given time of the evolution enters
explicitly.


title:
QCD Analysis of Diffractive and Leading-Proton DIS Structure Functions
  in the Framework of Fracture Functions

abstract:
  We present a combined QCD analysis of recent data produced by the H1 and ZEUS
collaborations on the diffractive and leading-proton deep inelastic
positron--proton scattering structure functions, $F_2^{D(3)}$ and
$F_2^{LP(3)}$, respectively. It is shown that the QCD framework for
semi-inclusive processes, based on fracture functions, allows a unified
treatment of both diffractive and leading-proton processes, and offers a
precise perturbative QCD description for them, alternative to those that rely
on model-dependent assumptions, such as Regge factorization, or other
non-perturbative approaches


title: A quark mass definition adequate for threshold problems

abstract:
  Recent calculations of heavy quark cross sections near threshold at
next-to-next-to-leading order have found second-order corrections as large as
first-order ones. We analyse long-distance contributions to the heavy quark
potential in momentum and coordinate space and demonstrate that long-distance
contributions in momentum space are suppressed as $\Lambda_{QCD}^2/q^2$. We
then show that the long-distance sensitivity of order $\Lambda_{QCD} r$
introduced by the Fourier transform to coordinate space cancels to all orders
in perturbation theory with long-distance contributions to the heavy quark pole
mass. This leads us to define a subtraction scheme -- the `potential
subtraction scheme' -- in which large corrections to the heavy quark potential
and the `potential-subtracted' quark mass are absent. We compute the two-loop
relation of the potential-subtracted quark mass to the $\bar{\rm MS}$ quark
mass. We anticipate that threshold calculations expressed in terms of the
scheme introduced here exhibit improved convergence properties.


title: The importance of tau leptons for supersymmetry searches at the Tevatron

abstract:
  Supersymmetry is perhaps most effectively probed at the Tevatron through
production and decay of weak gauginos. Most of the analyses of weak gaugino
observables require electrons or muons in the final state. However, it is
possible that the gauginos will decay primarily to tau leptons, thus
complicating the search for supersymmetry. The motivating reasons for high tau
multiplicity final states are discussed in three approaches to supersymmetry
model building: minimal supergravity, gauge mediated supersymmetry breaking,
and more minimal supersymmetry. The concept of ``e/mu/tau candidate'' is
introduced, and an observable with three e/mu/tau candidates is defined in
analog to the trilepton observable. The maximum mass reach for supersymmetry is
then estimated when gaugino decays to tau leptons have full branching fraction.


title: Soft Terms in M-theory

abstract:
  We discuss dilaton and Moduli dominant SUSY breaking scenarios in M-theory.
In addition, for the nonperturbative superpotential from gaugino condensation,
we discuss the soft terms in the simplest model (only S and T moduli fields)
and in the $T^6/Z_{12}$ model from M-theory. From the phenomenology
consideration, we suggest massless scalar SUSY breaking scenario.