title:
The b->sgamma decay rate in NLO, Higgs boson limits, and LSP masses in
  the CMSSM

abstract:
  New NLO b->sgamma calculations have become available. We observe that at
large tanbeta the dominant NLO term of the chargino amplitude, which is
proportional to mu.tanbeta^2, changes the sign of this amplitude in a large
region of the CMSSM parameter space, so that the preferred sign of the Higgs
mixing parameter mu now agrees with the preferred sign of b-tau unification. We
find that the b->sgamma rate does not constrain the CMSSM anymore, if the
higher order contributions and its uncertainties from the incomplete
calculations are taken into account.
  The Higgs boson mass in the CMSSM is found to be between 110 and 120 GeV for
a top mass of 175 GeV, if the Higgs mass limit of 107.9 GeV from LEP, which
implies tanbeta>3.3, is taken into account The mean Higgs boson mass value and
its dominant errors are: m_h=115\pm 3(stop mass) \pm 1.5(stop mixing) \pm
2(theory) \pm 5(top mass) GeV. This Higgs mass range is valid for all tanbeta
values above 20 and decreases for lower tanbeta. If the presently claimed
evidence for dark matter by the DAMA Collaboration is interpreted as the
Lightest Supersymmetric Particle (LSP) of the CMSSM, then it is at the edge of
the parameter space allowed by the present Higgs limit of 107.9 GeV from LEP.


title: Quintessential Brane and the Cosmological Constant

abstract:
  We consider a quintessential sector realized on a hidden brane with a tiny
warp factor, which implies a small value of the effective four-dimensional
cosmological constant through an equation of motion for the quintessential
scalar.


title:
Electroweak Model Independent Tests for SU(3) Symmetry in Hadronic B
  Decays

abstract:
  We study effects of new physics beyond the Standard Model on SU(3) symmetry
in charmless hadronic two body B decays. It is found that several equalities
for some of the decay amplitudes, such as $A(B_d (B_u) \to \pi^+\pi^-,\pi^+ K^-
(\pi^- \bar K^0)) =A(B_s \to K^+ \pi^-, K^- K^+ (K^0 \bar K^0))$, $A(B_d \to
\pi^+\rho^-, \pi^- \rho^+, K^-\rho^+, \pi^+ K^{*-}) = A(B_s \to K^+ \rho^-,
\pi^- K^{*+}, K^- K^{*+}, K^+ K^{*-})$, $A(B_d (B_u) \to \rho^+\rho^-, \rho^+
K^{*-}(\rho^- \bar K^{*0})) =A(B_s \to K^{*+} \rho^-, K^{*-} K^{*+} (K^{*0}
\bar K^{*0}))$, predicted by SU(3) symmetry in the SM are not affected by new
physics. These relations provide important electroweak model independent tests
for SU(3) symmetry in B decays.


title: Transverse Lattice

abstract:
  The transverse lattice approach to non-perturbative light-front hamiltonian
QCD is described. Preliminary results on the pi-rho system are presented, at
fixed DLCQ and Tamm-Dancoff cut-offs. A renormalised, approximately Lorentz
covariant light-front hamiltonian is found to leading order of the
colour-dielectric expansion, compatible with a massless pion. The pi
light-front wavefunction is compared with experiment. Exclusive processes agree
reasonably well, given the approximations, but inclusive processes, sensitive
to higher Fock state structure, still exhibit large cut-off artifacts.


title: Vacuum fluctuations of \bar{q}q and values of low-energy constants

abstract:
  We discuss the influence of the vacuum fluctuations of \bar{q}q pairs on
low-energy constants and condensates. The analysis of the Goldstone boson
masses and decay constants shows that the three-flavour condensate and some
low-energy constants are very sensitive to the value of L_6, which measures the
Zweig-rule violation in the scalar channel. A chiral sum rule based on
experimental data in this channel is used to constrain L_6, confirming a
significant decrease between the two- and the three-flavor condensates.


title:
The compatibility of diffractive hard scattering in p pbar and ep
  collisions

abstract:
  We show that the data for diffractive dijet production at the Tevatron p pbar
collider are consistent with diffractive deep inelastic e p data collected at
HERA. The breakdown of factorization between the two data sets is naturally
explained by a strong tendency to populate the rapidity gap in the p pbar
diffractive process by secondaries from soft underlying interactions and by
bremsstrahlung associated with the presence of the hard dijet subprocess.


title:
Calculation of hyperfine splitting in mesons using configuration
  interaction approach

abstract:
  The spin - spin mass splitting of light, heavy and mixed mesons are described
within a good accuracy in the potential model with screened potential. We
conclude that the long - distance part of the potential cannot be pure scalar
and that a vector - scalar mixture is favoured. With the same parameters which
gives correct average mass spectrum excellent spin - spin splittings of heavy
quarkonia is obtained. The results are obtained by going beyond usually used
perturbation method, namely using configuration interaction approach.


title: Universal Unitarity Triangle and Physics Beyond the Standard Model

abstract:
  We make the simple observation that there exists a universal unitarity
triangle for all models, like the SM, the Two Higgs Doublet Models I and II and
the MSSM with minimal flavour violation, that do not have any new operators
beyond those present in the SM and in which all flavour changing transitions
are governed by the CKM matrix with no new phases beyond the CKM phase. This
universal triangle can be determined in the near future from the ratio (Delta
M)_d/(Delta M)_s and sin(2 beta) measured first through the CP asymmetry in
B_d^0 to psi K_S and later in K to pi nu nubar decays. Also suitable ratios of
the branching ratios for B to X_{d,s} nu nubar and B_{d,s} to mu^+ mu^- and the
angle gamma measured by means of CP asymmetries in B decays can be used for
this determination. Comparison of this universal triangle with the
non-universal triangles extracted in each model using epsilon, (Delta M)_d and
various branching ratios for rare decays will allow to find out in a
transparent manner which of these models, if any, is singled out by experiment.
A virtue of the universal triangle is that it allows to separate the
determination of the CKM parameters from the determination of new parameters
present in the extensions of the SM considered here.


title: On Measurement of Helicity Parameters in Top Quark Decay

abstract:
  To enable an evaluation of future measurements of the helicity parameters for
" t --> W b " decay in regard to " T_FS violation", this paper considers the
effects of an additional pure-imaginary coupling, (i g/2 Lambda) or (i g),
associated with a specific, single additional Lorentz structure, i = S, P, S +
P, ... Sizable " T_FS violation" signatures can occur for low-effective mass
scales (< 320 GeV), but in most cases can be more simply excluded by 10%
precision measurement of the probabilities P(W_L) and P(b_L). Signatures for
excluding the presence of " T_FS violation" associated with the two dynamical
phase-type ambiguities are investigated.


title: A simple criterion for effects beyond hard thermal loops

abstract:
  Thermal amplitudes with ultrasoft momenta, which are not accessible by
standard methods of perturbation theory, have recently attracted a lot of
interest. However, the comparison of external momenta with the ultrasoft scale
$g^2T\ln(1/g)$ is a too crude criterion, since amplitudes with hard external
momenta can also be non perturbative, if these momenta are close enough to the
light-cone. In this letter, I give a more refined criterion to decide if an
amplitude is non perturbative, that applies to all situations. In physical
terms, this condition states that non-perturbative effects appear if the
particles running in loops have to travel distances larger than their mean free
path.


title:
Three-loop Three-Linear Vertices and Four-Loop MOM beta functions in
  massless QCD

abstract:
  In this paper we present a full set of 2- and 3-point functions for massless
QCD at three-loop order in the MSbar scheme. The vertex functions are evaluated
at the asymmetric point with one vanishing momentum. These results are used to
relate the MSbar coupling constant to that of various momentum subtraction
renormalization schemes at three-loop order. With the help of the known
four-loop MS-bar beta-function we then determine the four-loop coefficients of
the corresponding MOM beta-functions.
  As an application we consider the momentum dependence (running) of the
three-gluon asymmetrical vertex recently computed within the lattice approach
by Ph. Boucaud et al. (JHEP 04 006 (2000)). An account of the four-loop term in
the corresponding beta-function leads to a significant (around 30%) decrease of
the value of the non-perturbative power-suppressed correction to the running.


title:
Off-Shell Effective Lagrangian for NRQCD and Heavy Quarks Effective
  Theory

abstract:
  derivation of the effective lagrangian for non-relativistic quantum
chromodynamics and the heavy quarks effective field theory is given. Our
calculation provides of a simple and systematic method of calculation of the
full off shell effective lagrangian at tree level including all the $1/m$
corrections.


title:
Charged radiative pion capture on the nucleon in heavy baryon chiral
  perturbation theory

abstract:
  The differential cross sections and s-wave and p-wave multipoles for $\pi^- p
\to \gamma n$ and $\pi^+ n \to \gamma p$ have been calculated through $O(p^3)$
in heavy baryon chiral perturbation theory (HBChPT). Fits to existing data
allow several of the low energy constants to be determined. Generally results
of the calculation compare well with dispersion relation predictions.


title: Complete fermionic two-loop results for the M_W-M_Z interdependence

abstract:
  The complete fermionic two-loop contributions to the prediction for the
W-boson mass from muon decay in the electroweak Standard Model are evaluated
exactly, i.e. no expansion in the top-quark and the Higgs-boson mass is made.
The result for the W-boson mass is compared with the previous result of an
expansion up to next-to-leading order in the top-quark mass. The predictions
are found to agree with each other within about 5 MeV. A simple
parameterization of the new result is presented, approximating the full result
better than 0.4 MeV for M_H < 1 TeV.


title: Chiral QCD: Baryon dynamics

abstract:
  I review the consequences of the chiral symmetry of QCD for the structure and
dynamics of the low-lying baryons, with particular emphasis on the nucleon.


title: Finite Temperature Meson Correlation Functions in HTL Approximation

abstract:
  We calculate temporal correlators and their spectral functions with meson
quantum numbers in the deconfined phase of QCD using the hard thermal loop
(HTL) approximation for the quark propagator. Although this approach does not
result in a complete next-to-leading order perturbative calculation it takes
into account important medium effects such as thermal quark masses and Landau
damping in the quark-gluon plasma. We show that both effects lead to competing
modifications of the free mesonic correlation functions. We find that
correlators in scalar channels are only moderately influenced by the HTL medium
effects, while the HTL-vertex corrections lead to divergent vector correlators.


title: Linear Collider Physics

abstract:
  Studies of the physics potential of the Future Linear Collider are
establishing a broad programme which will start in the region of 350 to 500 GeV
C. of M. energy. The main goal is to understand why the standard model works;
by studying the properties of the Higgs sector, if it is within reach, and by
exploring the complex world of Supersymmetry, if it is real. If the Higgs boson
is not found soon, then the Linear Collider can test the standard model with
high precision measurements, both at energies approaching 1 TeV and with high
statistics at the Z0.


title: K0 form factor at order p^6 of chiral perturbation theory

abstract:
  This paper describes the calculation of the electromagnetic form factor of
the K0 meson at order p^6 of chiral perturbation theory which is the
next-to-leading order correction to the well-known p^4 result achieved by
Gasser and Leutwyler. On the one hand, at order p^6 the chiral expansion
contains 1- and 2-loop diagrams which are discussed in detail. Especially, a
numerical procedure for calculating the irreducible 2-loop graphs of the sunset
topology is presented. On the other hand, the chiral Lagrangian L^6 produces a
direct coupling of the K0 current with the electromagnetic field tensor. Due to
this coupling one of the unknown parameters of L^6 occurs in the contribution
to the K0 charge radius.


title:
Electroweak double logarithms in inclusive observables for a generic
  initial state

abstract:
  High energy observables are characterized by large electroweak radiative
corrections of infrared origin; double logarithms are present even for
inclusive cross sections, thus violating the Bloch Nordsieck theorem. This
effect, related to the initial states carrying nonabelian isospin charges, is
here investigated for {\sl any} inclusive cross section in the
SU(2)$\otimes$U(1) symmetric limit, that is appropriate for energies much
higher than the weak scale. We develop a general formalism allowing to
calculate the all order double log resummed cross sections once the hard (tree
level) ones are known. The relevant cases of fermion-fermion, fermion-boson and
boson-boson scattering are discussed.


title: Signals of the degenerate BESS model at the LHC

abstract:
  We discuss the possible signals of the degenerate BESS model at the LHC. This
model describes a strongly interacting scenario responsible of the spontaneous
breaking of the electroweak symmetry. It predicts two triplets of extra gauge
bosons which are almost degenerate in mass. Due to this feature, the model has
the property of decoupling and therefore, at low energies (below or of the
order of $100 GeV$) it is nearly indistinguishable from the Standard Model.
However the new resonances, both neutral and charged, should give quite
spectacular signals at the LHC, where the c.o.m. energy will allow to produce
these gauge bosons directly.


title:
Renormalization Group Flow Equations and the Phase Transition in
  O(N)-models

abstract:
  We derive and solve flow equations for a general O(N)-symmetric effective
potential including wavefunction renormalization corrections combined with a
heat-kernel regularization. We investigate the model at finite temperature and
study the nature of the phase transition in detail. Beta functions, fixed
points and critical exponents \beta, \nu, \delta and \eta for various N are
independently calculated which allow for a verification of universal scaling
relations.


title: Estimating the effect of NNLO contributions on global parton analyses

abstract:
  We use the recent estimates of NNLO splitting functions, made by van Neerven
and Vogt, to perform exploratory fits to deep inelastic and related hard
scattering data. We investigate the hierarchy of parton distributions obtained
at LO, NLO and NNLO, and, more important, the stability of the resulting
predictions for physical observables. We use the longitudinal structure
function $F_L$ and the cross sections $\sigma_W, \sigma_Z$ for $W$ and $Z$
hadroproduction as examples. For $F_L$ we find relatively poor convergence,
with increasing order, at small $x$; whereas $\sigma_{W,Z}$ are much more
reliably predicted.


title: The dynamics of the Goldstone bosons on the brane

abstract:
  We study, within the recently proposed brane-world scenario, the effective
action for the low-energy brane excitations. These modes are understood as
Goldstone bosons associated to the spontaneous isometry breaking, induced on
the bulk space by the presence of the brane. Starting from the Nambu-Goto
action for the brane, we obtain a non-linear sigma model describing the
low-energy interactions of the Goldstone bosons and extend the calculation up
to O(p^4). We also discuss the Higgs-like mechanism in which the Kaluza-Klein
gauge fields absorb the Goldstone bosons and acquire mass. Finally, we present
the explicit form of the effective action describing the low-energy
interactions between the three-brane Goldstone bosons and the particles present
in the Standard Model.


title: Large N_c in chiral perturbation theory

abstract:
  The construction of the effective Lagrangian relevant for the mesonic sector
of QCD in the large N_c limit meets with a few rather subtle problems. We
thoroughly examine these and show that, if the variables of the effective
theory are chosen suitably, the known large N_c counting rules of QCD can
unambiguously be translated into corresponding counting rules for the effective
coupling constants. As an application, we demonstrate that the Kaplan-Manohar
transformation is in conflict with these rules and is suppressed to all orders
in 1/N_c. The anomalous dimension of the axial singlet current generates an
additional complication: The corresponding external field undergoes
nonmultiplicative renormalization. As a consequence, the Wess-Zumino-Witten
term, which accounts for the U(3)_R x U(3)_L anomalies in the framework of the
effective theory, contains pieces that depend on the running scale of QCD. The
effect only shows up at nonleading order in 1/N_c, but requires specific
unnatural parity contributions in the effective Lagrangian that restore
renormalization group invariance.


title:
Effective Chiral Meson Lagrangian For The Extended Nambu-Jona-Lasinio
  Model

abstract:
  We present a derivation of the low-energy effective meson Lagrangian of the
extended Nambu -- Jona-Lasinio (ENJL) model. The case with linear realization
of broken $SU(2)\times SU(2)$ chiral symmetry is considered. There are two
crucial points why this revision is needed. Firstly it is the explicit chiral
symmetry breaking effect. On the basis of symmetry arguments we show that
relevant contributions related with the current quark mass terms are absent
from the effective Lagrangians derived so far in the literature. Secondly we
suggest a chiral covariant way to avoid non-diagonal terms responsible for the
pseudoscalar -- axial-vector mixing from the effective meson Lagrangian. In the
framework of the linear approach this diagonalization has not been done
correctly. We discuss as well the $SU(2)\times SU(2)/SU(2)$ coset space
parametrization for the revised Lagrangian (nonlinear ansatz). Our Lagrangian
differs in an essential way from those that have been derived till now on the
basis of both linear and nonlinear realizations of chiral symmetry.


title: Twist-4 quark-quark correlations in the pion from the instanton vacuum

abstract:
  The result for the matrix element A(I=2) = -0.14 F_pi^2 appears to be an
artifact of an improper ultraviolet regularization. Paper withdrawn pending
resolution of this problem.


title: The impact of atomic precision measurements in high energy physics

abstract:
  In this talk I discuss the relevance of atomic physics in understanding some
important questions about elementary particle physics. A particular attention
is devoted to atomic parity violation measurements which seem to suggest new
physics beyond the Standard Model. Atomic physics might also be relevant in
discovering possible violations of the CPT symmetry.


title:
A new method to measure the CP violating angle gamma using B^\pm ->
  pi^\pm pi^+ pi^- and B^\pm -> K^\pm pi^+ pi^- decays

abstract:
  A new and simple procedure to measure the angle $\gamma$ from $B^{\pm} \to
\pi^{\pm}\pi^+\pi^-$ and $B^{\pm} \to K^{\pm}\pi^+\pi^-$ decays using SU(3)
symmetry is presented. It is based on a full Dalitz plot analysis of these
decays. All diagrams, including strong and electroweak penguins, are considered
in the procedure. The method is also free from final state interaction
problems. The theoretical error in the extraction of $\gamma$ within the method
should be of the order of $10^{\rm o}$ or even less. Taking into account the
B-meson production in the first generation of B factories and recent
measurements from CLEO, this method could bring the best measurement of
$\gamma$ in the next years.


title: Maximum entropy method and oscillations in the diffraction cone

abstract:
  The maximum entropy method has been applied to investigate the oscillating
structure in the pbarp- and pp-elastic scattering differential cross-section at
high energy and small momentum transfer. Oscillations satisfying quite
realistic reliability criteria have been found.


title: Reconstructing Supersymmetric Theories at High Energy Scales

abstract:
  We have studied the reconstruction of supersymmetric theories at high scales
by evolving the fundamental parameters from the electroweak scale upwards.
Universal minimal supergravity and gauge mediated supersymmetry breaking have
been taken as representative alternatives. Pseudo-fixed point structures
require the low-energy boundary values to be measured with high precision.


title: The initial gluon multiplicity in heavy ion collisions

abstract:
  The initial gluon multiplicity per unit area per unit rapidity, dN/L^2/d\eta,
in high energy nuclear collisions, is equal to f_N (g^2\mu L) (g^2\mu)^2/g^2,
with \mu^2 proportional to the gluon density per unit area of the colliding
nuclei. For an SU(2) gauge theory, we compute f_N (g^2\mu L)=0.14\pm 0.01 for a
wide range in g^2\mu L. Extrapolating to SU(3), we predict dN/L^2/d\eta for
values of g^2\mu L in the range relevant to the Relativistic Heavy Ion Collider
and the Large Hadron Collider. We compute the initial gluon transverse momentum
distribution, dN/L^2/d^2 k_\perp, and show it to be well behaved at low
k_\perp.


title: How to resum long-distance contributions to the QCD pressure?

abstract:
  The strict coupling constant expansion for the free energy of hot QCD plasma
shows bad convergence at all reasonable temperatures, and does not agree well
with its 4d lattice determination. This has recently lead to various refined
resummations, whereby the agreement with the lattice result should improve, at
the cost of a loss of a formal agreement with the coupling constant expansion
and particularly with its large infrared sensitive ``long-distance''
contributions. We show here how to resum the dominant long-distance effects by
using a 3d effective field theory, and determine their magnitude by simple
lattice Monte Carlo simulations.


title: The $\gamma \gamma \to A^0 A^0$ process at a $\gamma \gamma $ Collider

abstract:
  The helicity amplitudes for the process $\gamma \gamma \to A^0 A^0$ are
studied to 1-loop order in the minimal SUSY (MSSM) model, where $A^0$ is the
CP-odd Higgs particle.
  Simple exact analytic formulae are obtained, in terms of the $C_0$ and $D_0$
Passarino-Veltman functions; in spite of the fact that the loop-diagrams often
involve different particles running along their sides. For a usual mSUGRA set
of parameters, $\sigma (\gamma \gamma \to A^0 A^0) \sim (0.1-0.2)\rm fb $ is
expected. If SUSY is realized in Nature, these expressions should be useful for
understanding the Higgs sector.


title: Photoproduction of Charmonia and Total Charmonium-Proton Cross Sections

abstract:
  Elastic virtual photoproduction cross sections gamma^*p -> J/psi(psi')p and
total charmonium-nucleon cross sections for J/psi, psi' and chi states are
calculated in a parameter free way with the light-cone dipole formalism and the
same input: factorization in impact parameters, light-cone wave functions for
the gamma^* and the charmonia, and the universal phenomenological dipole cross
section which is fitted to other data. The charmonium wave functions are
calculated with four known realistic potentials, and two models for the dipole
cross section are tested. Very good agreement with data for the cross section
of charmonium photoproduction is found in a wide range of s and Q^2. The
inclusion of the Melosh spin rotation increases the psi' photoproduction rate
by a factor 2-3 and removes previously observed discrepancies in the psi' to
J/psi ratio in photoproduction. We also calculate the charmonium-proton cross
sections whose absolute values and energy dependences are found to correlate
strongly with the sizes of the states.


title: The pi pi S-wave scattering lengths

abstract:
  We match the known chiral perturbation theory representation of the pi pi
scattering amplitude to two loops with a phenomenological description that
relies on the Roy equations. On this basis, the corrections to Weinberg's low
energy theorems for the S-wave scattering lengths are worked out to second
order in the expansion in powers of the quark masses. The resulting
predictions, a00=0.220 \pm 0.005, a20=-0.0444 \pm 0.0010, contain remarkably
small uncertainties and thus allow a very sensitive experimental test of the
hypothesis that the quark condensate is the leading order parameter of the
spontaneously broken chiral symmetry.


title: Exploration of Elastic Scattering Rates for Supersymmetric Dark Matter

abstract:
  We explore the possible cross sections for the elastic scattering of
neutralinos chi on nucleons p,n in the minimal supersymmetric extension of the
standard model (MSSM). Universality of the soft supersymmetry-breaking scalar
masses for the Higgs multiplets is not assumed, but the MSSM parameters are
nevertheless required to lead consistently to an electroweak vacuum. We explore
systematically the region of MSSM parameter space where LEP and other
accelerator constraints are respected, and the relic neutralino density lies in
the range 0.1 < Omega_chi h^2 < 0.3 preferred by cosmology. We also discuss
models with Omega_chi h^2 < 0.1, in which case we scale the density of
supersymmetric dark matter in our galactic halo by Omega_chi h^2 / 0.1,
allowing for the possible existence of some complementary form of cold dark
matter. We find values of the cross sections that are considerably lower than
the present experimental sensitivities. At low neutralino masses, m_chi < 100
GeV, the cross sections may be somewhat higher than in the constrained MSSM
with universal soft Higgs masses, though they are generally lower. In the case
of large m_chi, the cross sections we find may be considerably larger than in
the constrained model, but still well below the present experimental
sensitivity.


title: Phenomenology and Cosmology of Supersymmetric Grand Unified Theories

abstract:
  The cosmological relic density of a Bino-like Lightest Supersymmetric
Particle is calculated in the framework of the Minimal Supersymmetric Standard
Model. We include annihilation and coannihilation effects of the Bino with the
lightest stau and with the other sleptons, which happen to have comparable
masses with it. Coannihilation turns out to be crucial for reducing the Bino
relic density to an acceptable level. Phenomenological constraints, also,
results from the inclusion of the supersymmetric corrections to the CP-even
Higgs boson and b-quark masses and the branching ratio of b -->s gamma. We
impose these constraints on two versions of the Minimal Supersymmetric Standard
Model, employing radiative electroweak breaking with universal boundary
conditions and gauge coupling unification. In the first version of the model we
assume Yukawa coupling unification and boundary conditions from
gravity-mediated supersymmetry breaking. In the second version of the model we
assume boundary conditions from the Horava-Witten theory and we restrict the
parameter space by simultaneously imposing the phenomenological and
cosmological constraints.


title:
Manifestation of Jet Quenching in the Total Transverse Energy
  Distributions in the Nucleus-Nucleus Collisions

abstract:
  In the framework of the HIJING model global characteristics of nucleus-
nucleus collisions are studied for a Large Hadron Collider energy scale. An
interesting model prediction is the presence of a central bump over a
pseudorapidity plateau of a total transverse energy distribution. The bump is
induced by a jet quenching effect in a dense nuclear matter. It is shown that
on a wide acceptance calorimeter with a pseudorapidity coverage
  -5 < \eta < 5 allow to obtain experimental confirmation of such an effect.


title: Nonequilibrium perturbation theory for spin-1/2 fields

abstract:
  A partial resummation of perturbation theory is described for field theories
containing spin-1/2 particles in states that may be far from thermal
equilibrium. This allows the nonequilibrium state to be characterized in terms
of quasiparticles that approximate its true elementary excitations. In
particular, the quasiparticles have dispersion relations that differ from those
of free particles, finite thermal widths and occupation numbers which, in
contrast to those of standard perturbation theory evolve with the changing
nonequilibrium environment. A description of this kind is essential for
estimating the evolution of the system over extended periods of time. In
contrast to the corresponding description of scalar particles, the structure of
nonequilibrium fermion propagators exhibits features which have no counterpart
in the equilibrium theory.


title: Dynamical Cosmological Constant from A Very Recent Phase Transition

abstract:
  Observation indicates that the expansion of the Universe is accelerating and
favours a dynamical cosmological constant, \Lambda(t). We consider the
possibility that this is due to a scalar field which has undergone a very
recent phase transition. We study a simple class of model, corresponding to a
\phi^4 potential with a time-dependent mass squared term. For the models
considered the phase transition occurs at a red shift z \leq 1.2. The evolution
of the equation of state \omega_{\phi} and energy density \rho_{\phi} with time
is distinct from existing dynamical \Lambda models based on slowly rolling
fields, with \omega_{\phi} and \rho_{\phi} rapidly changing in a characteristic
way following the transition. The \phi energy density is composed of a
time-dependent vacuum energy and coherently oscillating condensate component
with a negative pressure. The condensate component will collapse to form
non-topological soliton lumps, '\phi-axitons', which smoothly populate the
Universe.


title: Check of the Bootstrap Conditions for the Gluon Reggeization

abstract:
  The property of gluon Reggeization plays an essential role in the derivation
of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation for the cross sections at
high energy $\sqrt s$ in perturbative QCD. This property has been proved to all
orders of perturbation theory in the leading logarithmic approximation and it
is assumed to be valid also in the next-to-leading logarithmic approximation,
where it has been checked only to the first three orders of perturbation
theory. From $s$-channel unitarity, however, very stringent ``bootstrap''
conditions can be derived which, if fulfilled, leave no doubts that gluon
Reggeization holds.


title: Next-to-leading virtual photon - Reggeized gluon interaction

abstract:
  We present the results of the calculation of the one-loop correction to the
effective vertex for the quark-antiquark pair production in collisions of the
virtual photon with the Reggeized gluon. This vertex is supposed then to be
used for the calculation of the virtual photon impact factor, which is
extremely important, for instance, for the description of the small $x$ deep
inelastic scattering in the BFKL approach.


title: Deep inelastic leptoproduction of spin-one hadrons

abstract:
  In this paper we analyze deep inelastic one-particle inclusive processes for
the case of spin-one targets or for the case of spin-one produced hadrons, such
as rho mesons. This allows the measurement of new distribution and
fragmentation functions not available in the spin-half case, and provides new
ways to probe functions otherwise difficult to measure. We will analyze only
contributions leading order in 1/Q, but we will include effects of the
transverse momentum of partons. We also include time-reversal odd functions.


title:
Charge diffusion constant in hot and dense hadronic matter - A
  Hadro-molecular-dynamic calculation

abstract:
  We evaluate charge diffusion constant of dense and hot hadronic matter based
on the molecular dynamical method by using a hadronic collision generator which
describes nuclear collisions at energies 10 < E < 100 GeV/A and satisfies
detailed balance at low temperatures (T < 200 MeV). For the hot and dense
hadronic matter of the temperature range, 100 < T < 200 MeV and baryon number
density, 0.16 < nB < 0.32 fm^-3, charge diffusion constant D gradually
increases from 0.5 fm c to 2 fm c with temperature and is almost independent of
baryon number density. Based on the obtained diffusion constant we make simple
discussions on the diffusion of charge fluctuation in ultrarelativistic nuclear
collisions.


title:
HIJING Model Prediction on Squeeze-Out of Particles in Nucleus-Nucleus
  Interactions at Super High Energies

abstract:
  Elliptic flow of hard partons (P>5 GeV), squeeze-out of soft partons (P<=5
GeV) and produced particles are predicted in the framework of the HIJING model.
They are caused due to jet quenching and heterogeneity of the interaction
region.


title: No Primordial Magnetic Field from Domain Walls

abstract:
  It is pointed out that, contrary to some claims in the literature, the domain
walls cannot be a source of a correlated at large scales primordial magnetic
field, even if the fermionic modes bound on the wall had ferromagnetic
properties. In a particular model with massive (2+1) dimensional fermions bound
to a domain wall, previously claimed to exhibit a ferromagnetic behavior, it is
explicitly shown that the fermionic system in fact has properties of a normal
diamagnetic with the susceptibility vanishing at high temperature.


title:
Transversality of the logarithmic divergences in the Classical Finite
  Temperature SU(N) Self-Energy

abstract:
  We show that the logarithmic divergences that appear in the classical
approximation of the finite temperature SU(N) self-energy are transverse. We
use the Ward identities in linear gauges and the fact that the superficial
degree of divergence d of a classical diagram only depends on the number of
loops l via d=2-l. We comment on the relevance of this result to the
construction of a low-energy effective theory beyond HTLs.


title:
Quantum Fiel Theoretic Treatment of the Non-Forward Compton Amplitude in
  the Generalized Bjorken Region

abstract:
  A quantum field theoretic treatment of the leading light-cone part of the
virtual Compton amplitude is presented. The twist-decomposition of the
operators is performed by a group-theoretic procedure respecting the Lorentz
group O(3,1). The twist-2 contributions to the Compton amplitude are calculated
and it is shown that the electromagnetic current is conserved for these terms.
Relations between the amplitude functions associated to the symmetric and
asymmetric part of the Compton amplitude are derived. These relations
generalize the Callan-Gross and Wandzura-Wilczek relations of forward
scattering for the non-forward Compton amplitude.


title: How to Interpret a Tau Excess at LEP2 within the MSSM

abstract:
  Neutralino and tau slepton pair production can naturally produce an excess of
tau lepton pairs at the current LEP collider energies. We describe the
constraints this has on the values of the mass parameters in the softly broken
Supersymmetric Lagrangian, and consider the consequences for superpartner
production at LEP and at the Fermilab Tevatron collider. The pair production of
the LSP and a heavier neutralino, followed by a 2-body decay to a tau slepton
and tau lepton, is consistent with the present LEP data, predicts a chargino
mass below 125 GeV, and provides an interesting Cold Dark Matter component,
with a relic matter density of .1-.2.


title: Probing chiral symmetry of nucleon by threshold $\eta \pi$ production

abstract:
  Double meson production of the eta and pion at the threshold region is
investigated in order to determine chiral property of the nucleon.
  The eta can be used as a probe for the negative parity nucleon $N^* \equiv
N^*(1535)$ produced in the intermediate state.
  The coupling of the low energy pion in the final state is then used to
extract the sign of the Yukawa coupling, $\gpRR$, which distinguishes the two
realizations of chiral symmetry, either naive or mirror, for the nucleon.


title:
Global Features of Nucleus-Nucleus Collisions in the Ultrarelativistic
  Domain

abstract:
  HIJING generator simulation of nucleus-nucleus collisions at
ultrarelativistic energies are presented. Is shown, that the global
characteristics of nucleus-nucleus collisions, such as of distribution of a
charge multiplicity, total and electromagnetic transverse energy over
pseudorapidity are rather sensitive to some predictions of formation models of
high-exited nuclear medium, namely parton energy losses in dense nuclear
matter. This losses results to appearance of a broad maximum in global variable
distributions over pseudorapidity. The most profound of this effect occurs at
central heavy ion collisions at LHC energy.


title: Calculation of fermionic two-loop contributions to muon decay

abstract:
  The computation of the correction \Delta r in the W-Z mass correlation,
derived from muon decay, is described at the two-loop level in the Standard
Model. Technical aspects which become relevant at this level are studied, e.g.
gauge-parameter independent mass renormalization, ghost-sector renormalization
and the treatment of \gamma_5. Exact results for \Delta r and the W mass
prediction including O(\alpha^2) corrections with fermion loops are presented
and compared with previous results of a next-to-leading order expansion in the
top-quark mass.


title:
Global Characteristics of Nucleus-Nucleus Collisions in an
  Ultrarelativistic Domain

abstract:
  The global observable distributions of nucleus-nucleus collisions at high
energy are studied. It is shown that these distributions are sensitive to
interaction dynamics and can be used to investigate the evolution of dense
nuclear matter. At the LHC energy scale ($\sqrt{s_{NN}}=5$ TeV in the heavy ion
mode), a central bump over pseudorapidity plateau in the differential
distributions of total transverse energy flows induced by the jet quenching
effect was obtained. The energy-loss dependence on the energy for various
colliding ion species was explored. Also a new scheme for collision geometry
determination is proposed as well. It is based on the correlation between
transverse energy flow in the pseudorapidity interval $3<|\eta|<5$ and an
impact parameter.


title: Scalar Mesons in a Chiral Quark Model with Glueball

abstract:
  Ground-state scalar isoscalar mesons and a scalar glueball are described in a
U(3)xU(3) chiral quark model of the Nambu--Jona-Lasinio (NJL) type with 't
Hooft interaction. The latter interaction produces singlet-octet mixing in the
scalar and pseudoscalar sectors. The glueball is introduced into the effective
meson Lagrangian as a dilaton on the base of scale invariance. The mixing of
the glueball with scalar isoscalar quarkonia and amplitudes of their decays
into two pseudoscalar mesons are shown to be proportional to current quark
masses, vanishing in the chiral limit. Mass spectra of the scalar mesons and
the glueball and their main modes of strong decay are described.


title:
Search for new physics in $\Delta S = 2$ two - body (VV, PP, VP) decays
  of the B^- - meson

abstract:
  The $\Delta S = 2$ $b \to \bar d ss$ transition proceeds via the box -
diagram in the Standard Model with a branching ratio calculated to be below
$10^{-11}$, thus providing an appropriate testing ground for physics beyond the
Standard Model. We analyze the $\Delta S = 2$ two - body $B^- \to K^{*-} \bar
K^{*0}$, $B^- \to K^- \bar K^{0}$, $B^- \to K^{*-} \bar K^{0}$ and $B^- \to
K^{-} \bar K^{*0}$ exclusive decays which are driven by the $b \to \bar d ss$
transition, both in the Standard Model and in several extensions of it. The
models considered are the minimal supersymmetric model with and without ${\cal
R}$ parity conservation and two Higgs doublet models. All four modes are found
to have a branching ratio of the order of $10^{-13}$ in the Standard Model,
while the expected branching ratio in the different extensions vary between
$10^{-9} - 10^{-6}$.


title:
Longitudinal Resolution in a Large Relativistic Nucleus: Adding a
  Dimension to the McLerran-Venugopalan Model

abstract:
  We extend the McLerran-Venugopalan model for the gluon distribution functions
of very large nuclei to larger values of the longitudinal momentum fraction xF.
Because gluons with larger values of xF begin to resolve the longitudinal
structure of the nucleus, we find that it is necessary to set up a fully
three-dimensional formalism for performing the calculation. We obtain a
relatively compact expression for the gluon number density provided that the
nucleus is sufficiently large and consists of color-neutral nucleons. Our
expressions for the gluon number density saturate at small transverse momenta.
The nuclear dependence we obtain is such that the number of gluons increases
more slowly than the number of nucleons is increased.


title:
Renormalization of supersymmetric Yang-Mills theories with soft
  supersymmetry breaking

abstract:
  The renormalization of supersymmetric Yang-Mills theories with soft
supersymmetry breaking is presented using spurion fields for introducing the
breaking terms. It is proven that renormalization of the fields and parameters
in the classical action yields precisely the correct counterterms to cancel all
divergences. In the course of the construction of higher orders additional
independent parameters appear, but they can be shown to be irrelevant in
physics respects. Thus, the only parameters with influence on physical
amplitudes are the supersymmetric and the well-known soft breaking parameters.


title: Neutrino Mixing and CP Violation in Matter

abstract:
  Within the framework of three lepton families I present a transparent
analytical relationship between the neutrino mixing and CP-violating parameters
in vacuum and thos in matter. Such a model- and parametrization-independent
result will be particularly useful to recast the fundamental lepton flavor
mixing matrix from the future long-baseline neutrino experiments.


title: Final-state Rescattering Effects on B_d-->\pi\pi Decays and CP Violation

abstract:
  The significance of final-state interactions in B_d-->\pi\pi decays is
phenomenologically demonstrated by taking elastic \pi\pi--\pi\pi and inelastic
\pi\pi--D\bar{D} rescattering effects into consideration. We find that the
present experimental data on B^0_d-->\pi^+\pi^- can well be understood in this
approach without fine-tuning of the input parameters, and large CP-violating
asymmetries are expected to manifest themselves in such charmless rare
processes.


title: Final State Interactions in eps'/eps

abstract:
  I shortly review the present status of the theoretical estimates of eps'/eps.
I consider a few aspects of the theoretical calculations which may be relevant
in understanding the present experimental results. In particular, I discuss the
role of final state interactions and in general of non-factorizable
contributions for the explanation of the Delta I = 1/2 selection rule in kaon
decays and eps'/eps. Lacking reliable lattice calculations, the 1/N expansion
and phenomenological approaches may help in understanding correlations among
theoretical effects and the experimental data. The same dynamics which
underlies the CP conserving selection rule may drive eps'/eps in the range of
the recent experimental measurements.


title:
Thermal Green Functions in Coordinate Space for Massless Particles of
  any Spin

abstract:
  The thermal Wightman functions for free, massless particles of spin 0, 1/2,
1, 3/2, and 2 are computed directly in coordinate space by solving the
appropriate differential equation and imposing the Kubo-Martin-Schwinger
condition. The solutions are valid for real, imaginary, or complex time. The
Wightman functions for spin 1 gauge bosons and for spin 2 gravitons are
directly related to the fundamental functions for spin 0. The Wightman
functions for spin 3/2 gravitinos is directly related to that for spin 1/2
fermions. Calculations for spin 1, 3/2, and 2 are done in covariant gauges. In
the deep space-like region the Wightman functions for bosons fall like $T/r$
whereas those for the fermions fall exponentially. In the deep time-like region
all the Wightman functions fall exponentially.


title:
Signals for Gauge Mediated Supersymmetry Breaking Model at an {${\bf
  e}^{\bf -}{\bf e}^{\bf -}$} Collider

abstract:
  We study the pair-production and decay of right handed selectrons within a
Gauge Mediated Supersymmetry Breaking Model in polarised $e^-e^-$ interaction.
Detailed analyses of the possible signals and backgrounds are performed for a
few selected points in the parameter space. A judicious choice for polarisation
of the initial electron beam helps eliminate almost the entire Standard Model
background. We also show that phase space distributions can be used to
distinguish such a supersummetry breaking scheme from the supergravity inspired
models.


title: Large-x Parton Distributions

abstract:
  Reliable knowledge of parton distributions at large x is crucial for many
searches for new physics signals in the next generation of collider
experiments. Although these are generally well determined in the small and
medium x range, it has been shown that their uncertainty grows rapidly for
x>0.1. We examine the status of the gluon and quark distributions in light of
new questions that have been raised in the past two years about "large-x"
parton distributions, as well as recent measurements which have improved the
parton uncertainties. Finally, we provide a status report of the data used in
the global analysis, and note some of the open issues where future experiments,
including those planned for Jefferson Labs, might contribute.


title: Parton Densitites at High-x

abstract:
  Reliable knowledge of parton distributions at large x is crucial for many
searches for new physics signals in the next generation of collider
experiments. Although these are generally well determined in the small and
medium x range, it has been shown that their uncertainty grows rapidly for
x>0.1. We examine the status of the distributions in light of new questions
that have been raised about "large-x" parton distributions, as well as recent
measurements which have improved the parton uncertainties.


title: The soft-gluon current at one-loop order

abstract:
  We study the soft limit of one-loop QCD amplitudes and we derive the
process-independent factorization formula that controls the singular behaviour
in this limit. This is obtained from the customary eikonal factorization
formula valid at tree (classical) level by introducing a generalized soft-gluon
current that embodies the quantum corrections. We compute the explicit
expression of the soft-gluon current at one-loop order. It contains purely
non-abelian correlations between the colour charges of each pair of
hard-momentum partons in the matrix element. This leads to colour correlations
between (two and) three hard partons in the matrix element squared. Exploiting
colour conservation, we recover QED-like factorization for the square of the
matrix elements with two and three hard partons.


title: Quark-Antiquark Bound States and the Breit Equation

abstract:
  A non-covariant but approximately relativistic two-body wave equation (Breit
equation) describing the quantum mechanics of two fermions interacting with one
another through a potential containing scalar, pseudoscalar and vector parts is
presented. After expressing the sixteen component two-body wavefunction in
terms of a radial and an angular function by means of the multipole expansion,
the initial equation can be reduced into a set of sixteen radial equations
which, in turn, can be classified in accordance to the parity and the state of
the wavefunctions involved. The adequacy of the reduced equations in describing
real problems is discussed by applying the theory to QCD problems and the
calculation of the energies of bound states of quark-antiquark systems is
performed to order $\alpha^4$. We show that bound states of heavy quarks can be
described adequately by the Breit equation for a funnel interaction between the
particles


title:
Dispersion relation formalism for virtual Compton scattering and the
  generalized polarizabilities of the nucleon

abstract:
  A dispersion relation formalism for the virtual Compton scattering (VCS)
reaction on the proton is presented, which for the first time allows a
dispersive evaluation of 4 generalized polarizabilities at a four-momentum
transfer $Q^2 \leq$ 0.5 GeV$^2$. The dispersive integrals are calculated using
a state-of-the-art pion photo- and electroproduction analysis. The dispersion
formalism provides a new tool to analyze VCS experiments above pion threshold,
thus increasing the sensitivity to the generalized polarizabilities of the
nucleon.


title: Explicit SO(10) Supersymmetric Grand Unified Model

abstract:
  A complete set of Higgs and matter superfields is introduced with
well-defined SO(10) properties and U(1) \times Z_2 \times Z_2 family charges
from which the Higgs and Yukawa superpotentials are constructed. The Higgs
fields solve the doublet-triplet splitting problem, while the structures of the
four Dirac fermion mass matrices obtained involve just six effective Yukawa
operators. The right-handed Majorana matrix, M_R, arises from one Higgs field
coupling to several pairs of superheavy conjugate neutrino singlets. In terms
of 10 input parameters to the mass matrices, the model accurately yields the 20
masses and mixings of the lightest quarks and leptons, as well as the masses of
the 3 heavy right-handed neutrinos. The bimaximal atmospheric and solar
neutrino vacuum solutions are favored in this simplest version with a moderate
hierarchy in M_R. The large mixing angle MSW solution is obtainable, on the
other hand, with a considerably larger hierarchy in M_R which is also necessary
to obtain baryogenesis through the leptogenesis mechanism.


title:
Off-diagonal structure of neutrino mass matrix in see-saw mechanism and
  electron-muon-tau lepton universality

abstract:
  By a simple extension of the standard model in which ($e-\mu -\tau $)
universality is not conserved, we present a scenario within the framework of
see-saw mechanism in which the neutrino mass matrix is strictly off-diagonal in
the flavor basis. We show that a version of this scenario can accomodate the
atmospheric $\nu_\mu -\nu_\tau $ neutrino oscillations and $\nu_\mu -\nu_e$
oscillations claimed by the LSND collaboration.
  PACS: 14.60.Pq; 14.60.St;13.15.+g


title: Flow equations in the light-front QCD

abstract:
  Flow equations method of continuous unitary transformations is used to
eliminate the minimal quark-gluon interaction in the light-front quantized QCD
Hamiltonian. The coupled differential equations in the two lowest Fock sectors
correspond to the renormalization of the light-front gluon mass and the
generation of effective quark-antiquark interaction. The influence of the
renormalization of the gluon effective mass on the elimination of the
quark-gluon coupling and the induced quark-antiquark interaction is taken into
account. Namely, the original gauge field coupling can be completely
eliminated, even when the states connected by this interaction are degenerate.
Furthermore, even in the case where effective interaction, obtained within
perturbative schemes (bound state perturbation theory or perturbative
similarity approach), is not defined, we obtain more singular behavior $1/q^4$
at small gluon momenta. This is due to asymptotic behavior of the effective
gluon mass at small cutoffs. By discussing the consequences of this asymptotic
behavior, it seems that our approach is superior to perturbation theory and to
perturbative similarity approach.


title:
Yukawa Unification and Unstable Minima of the Supersymmetric Scalar
  Potential

abstract:
  Motivated by the possibilities of $b-\tau$ or $t-b-\tau$ Yukawa unification
in the supersymmetric Grand Unified Theories, we consider the dangerous
directions of the supersymmetric potential for large values of $\tan\beta (\geq
30)$, in two versions of the minimal supergravity model with and without common
soft breaking scalar masses at the GUT scale, where the potential may become
unbounded from below. We find that for the common trilinear coupling $A_0 \leq
0$ the requirement of $b-\tau$ unification in conjunction with the stability
condition on the potential yields highly restrictive sparticle spectra with
upper, and in many cases, lower bounds stronger than the available experimental
lower bounds, on the soft SUSY breaking common scalar mass and the common
gaugino mass. Over a significant region of the parameter space, the model
becomes even more restrictive if the common sfermion soft mass is different
from the soft mass for the Higgs sector. We also find that the bulk of this
restricted parameter space can be probed at the LHC. Im models with $t-b-\tau$
Yukawa unification, $A_0 \leq 0$ is ruled out from potential constraints.


title: Compton-like interaction of massive neutrinos with virtual photons

abstract:
  The amplitude of a Compton-like process nu_i gamma^* -> nu_j gamma^* with
virtual photons is calculated in the standard GWS theory with lepton mixing.
The contribution of this process to the high energy neutrino scattering on the
nucleus with single photon radiation nu N -> nu N gamma is discussed. The
bremsspectrum and the total cross-section are estimated in the leading log
approximation.


title: Entropy in hadron-hadron collisions

abstract:
  We analyse the entropy properties in the proton-proton 1800 GeV events from
the PYTHIA/JETSET Monte Carlo generator following a recent proposal concerning
the measurement of entropy in multiparticle systems. The dependence on the
number of bins and on the size of the phase-space region is investigated. Our
results may serve as a reference sample for experimental data from
hadron-hadron and heavy ion collisions.


title: Chaotic sources and Percolation of strings

abstract:
  It is shown that different ways of interacting strings formed in high energy
nucleus-nucleus collisions cause a different strength of the chaoticity
parameter lambda of Bose-Einstein correlations. In particular, in the case of
percolation of strings, lambda shows a peculiar dependence on the string
density, very similar to the dependence of the fractional average cluster size.
In both, the derivative on the string density is maximum at the critical point.
The reasonable agreement with the existing experimental data indicates that
percolation of strings can actually occurs.


title:
Renormalons and multiloop estimates in scalar correlators, Higgs decay
  and quark-mass sum rules

abstract:
  The single renormalon-chain contribution to the correlator of scalar currents
in QCD is calculated in the $\bar{MS}$-scheme in the limit of a large $N_f$. We
find that in the factorial growth of the coefficients due to renormalons takes
over almost immediatelly in the euclidean region. The essential differences
between the large-order growth of coefficients in the scalar case, and in the
vector case are analysed. In the timelike region a stabilization of the
perturbative series for the imaginary part, with $n$-loop behaviour
$S_n/[\log(s/\Lambda^2)]^{n-1}$, where $S_n$ is essential constant for
$n\le{6}$, is observed. Only for $n\ge{7}$ does one discern the factorial
growth and alternations of sign. Out all-order results are used to scrutinize
the performance of multiloop estimates, within the ``naive nonabelianization''
procedure, and the effective charges approach. The asymtotic behaviour of
perturbative coefficients, in both large $N_f$ and large $N_c$ limits, is
analysed. A contour-improved resummation technique in the time-like region is
developed. Some subtleties of scheme-dependence are illustrated using results
in the $\bar{MS}$ and $V$-schemes. The all-order series under investigation are
summed up with the help of the Borel resummation method. The results obtained
are relevant to the analysis of the theoretical uncertainties in the 4-loop
extractions of the running and invariant $s$-quark masses from QCD sum rules,
and in calculations of the Higgs boson decay width into a quark-antiquark pair.


title:
Semi-inclusive production of pions in DIS and $\bar d - \bar u$
  asymmetry

abstract:
  We discuss the role of some nonpartonic effects which lead to $N_p^{\pi^+}
\ne N_n^{\pi^+}$ and $N_p^{\pi^-} \ne N_n^{\pi^-}$ and may therefore modify the
conclusionon the $\bar d - \bar u$ asymmetry extracted from semi-inclusive
production of pions in DIS. Quantitative estimations for resolved photon and
exclusive $\rho^0$ are given as examples. The results are discussed in the
context of recent HERMES data.


title: Four-neutrino oscillations and the solar neutrino problem

abstract:
  We perform a fit of solar neutrino data in the framework of the two
four-neutrino schemes that are compatible with the results of all neutrino
oscillation experiments. These schemes allow simultaneous transitions of solar
nu_e's into active nu_mu's, nu_tau's and sterile nu_s. The data imply that the
SMA solution is valid for any combination of nu_e->active and nu_e->sterile
transitions, whereas the LMA, LOW and VO solutions disappear when nu_e->nu_s
transitions are dominant.


title: A frequentist analysis of solar neutrino data

abstract:
  We calculate with Monte Carlo the goodness of fit and the confidence level of
the standard allowed regions for the neutrino oscillation parameters obtained
from the fit of solar neutrino data. We show that the values of the goodness of
fit and of the confidence level of the allowed regions are significantly
smaller than the standard ones. Using Neyman's method, we also calculate exact
allowed regions with correct frequentist coverage. We show that the standard
allowed region around the global minimum of the least-squares function is a
reasonable approximation of the exact one, whereas the size of the other
regions is dramatically underestimated in the standard method.


title: From Crepes to Pancakes in the MV Model

abstract:
  The McLerran-Venugopalan model provides a framework which allows one to
compute the gluon distribution function of a very large nucleus from the
equations of QCD, provided that the longitudinal momentum fraction, xF, is
sufficiently small. The source of color charge for this computation may be
thought of as a crepe moving along the z axis at the speed of light. We refine
the MV model by allowing for the presence of non-trivial longitudinal
correlations between the color charges that comprise the nucleons. We find that
a consistent treatment forces us to consider a pancake-like source which moves
at slightly less than the speed of light. Our calculation allows us to consider
larger values of xF than were allowed in the original MV model.


title:
Neutralino Phenomenology at LEP2 in Supersymmetry with Bilinear Breaking
  of R-parity

abstract:
  We discuss the phenomenology of the lightest neutralino in models where an
effective bilinear term in the superpotential parametrizes the explicit
breaking of R-parity. We consider supergravity scenarios where the lightest
supersymmetric particle (LSP) is the lightest neutralino and which can be
explored at LEP2. We present a detailed study of the LSP decay properties and
general features of the corresponding signals expected at LEP2. We also
contrast our model with gauge mediated supersymmetry breaking.


title: Ultra High Energy Cosmic Rays from Compact Sources

abstract:
  The clustering of ultra high energy (above 10^20 eV) cosmic rays (UHECR)
suggests that they might be emitted by compact sources. Statistical analysis of
Dubovsky et al. (Phys. Rev. Lett. 85 (2000) 1154) estimated the source density.
We extend their analysis to give also the confidence intervals for the number
of sources using a.) no assumptions on the relationship between clustered and
unclustered events; b.) nontrivial distributions for the source intensities and
energies; c.) the energy dependence of the propagation. We determine the
probability that a proton created at a distance r with energy E arrives at
earth above a threshold E_c. Using this function one can determine the observed
spectrum just by one numerical integration for any injection spectrum. The
observed 14 UHECR events above 10^20 eV with one doublet gives for the source
densities 180_-165^+2730*10^-3 Mpc^-3 (on the 68% confidence level). We present
detailed results for future experiments with larger UHECRs statistics.


title: Screened Perturbation Theory to Three Loops

abstract:
  The thermal physics of a massless scalar field with a phi^4 interaction is
studied within screened perturbation theory (SPT). In this method the
perturbative expansion is reorganized by adding and subtracting a mass term in
the lagrangian. We consider several different mass prescriptions that
generalize the one-loop gap equation to two-loop order. We calculate the
pressure and entropy to three-loop order and the screening mass to two-loop
order. In contrast to the weak-coupling expansion, the SPT-improved
approximations appear to converge even for rather large values of the coupling
constant.


title: Effective description of quark mixing

abstract:
  We use the effective Lagrangian formalism to describe quark mixing. The new
W, Z and H couplings generalizing the CKM matrix and the GIM mechanism fulfil
relations and inequalities which allow to discriminate among different SM
extensions. As a by-product we give a useful parametrization of the generalized
CKM matrix. We also show that the largest possible departures from the SM
predictions result from heavy exotic fermions, which can induce, for example,
top FCNC large enough to be observable at future colliders.


title: Perspectives in High-Energy Physics

abstract:
  A personal view of current prospectives in particle physics is presented,
inspired by the contributions to this meeting. Particular emphasis is laid in
precision tests of the Standard Model and the search for the Higgs boson, on
probes of CP violation, on speculations about possible physics beyond the
Standard Model, on neutrino masses and oscillations, on the quest for
supersymmetry, on opportunities @ future accelerators, and on the ultimate
phenomenological challenge offered by the quest for a Theory of Everything.


title: The lifetime of B_c-meson and some relevant problems

abstract:
  The lifetime of the B_c-meson is estimated with consistent considerations on
all of the heavy mesons ($B^0, B^\pm, B_s, D^0, D^\pm D_s$) and the double
heavy meson B_c. In the estimate, the framework, where the non-spectator
effects for nonleptonic decays are taken into account properly, is adopted, and
the parameters needed to be fixed are treated carefully and determined by
fitting the available data. The bound-state effects in it are also considered.
We find that in decays of the meson B_c, the QCD correction terms of the
penguin diagrams and the main component terms c_1O_1, c_2O_2 of the effective
interaction Lagrangian have direct interference that causes an enhancement
about 3 ~ 4% in the total width of the B_c meson.


title: Magnetogenesis and the dynamics of internal dimensions

abstract:
  The dynamical evolution of internal space-like dimensions breaks the
invariance of the Maxwell's equations under Weyl rescaling of the (conformally
flat) four-dimensional metric. Depending upon the number and upon the dynamics
of internal dimensions large scale magnetic fields can be created. The
requirements coming from magnetogenesis together with the other cosmological
constraints are examined under the assumption that the internal dimensions
either grow or shrink (in conformal time) prior to a radiation dominated epoch.
If the internal dimensions are growing the magnitude of the generated magnetic
fields can seed the galactic dynamo mechanism.


title:
Form factors for $B-->\pi l\nu$ decay in a model constrained by chiral
  symmetry and quark model

abstract:
  The form factors for the $B-->\pi$ transition are evaluated in the entire
momentum transfer range by using the constraints obtained in the framework
combining the heavy quark expansion and chiral symmetry for light quarks and
the quark model. In particular, we calculate the valence quark contributions
and show that it together with the equal time commutator contribution simulate
a B-meson pole q^2-dependence of form factors in addition to the usual vector
meson B^{*}-pole diagram for $B --> \pi l\nu$ in the above framework. We
discuss the predictions in our model, which provide an estimate of |V_{ub}|^2.


title:
Searching for a stop-pair sample from top counting experiments at hadron
  colliders

abstract:
  The light stop pair if produced in hadron colliders and decaying through the
likely decay chain stop->chargino + b followed by chargino->neutralino + f f',
can mimic closely a top quark event when the mass of the stop is close to that
of the top quark. Because of the much lower production rate, the stop event can
be buried under the top quark event sample. In order to uncover the stop event,
specific selection cuts need to be applied. Through Monte Carlo simulation with
suitable kinematic cuts, we found that such stop event can be extracted from
the top quark sample and detected by the top quark counting experiments in the
upcoming upgraded Tevatron and LHC. However, because of the small statistics of
the Run 1 of the Tevatron, the stop signal remains hidden at Run 1.


title: Back-Reaction In Lightcone QED

abstract:
  We consider the back-reaction of quantum electrodynamics upon an electric
field E(x_+) = - A'_-(x_+) which is parallel to x^3 and depends only on the
lightcone coordinate x_+ = (x^0 + x^3)/\sqrt{2}. Novel features are that the
mode functions have simple expressions for arbitrary A_-(x_+), and that one
cannot ignore the usual lightcone ambiguity at zero + momentum. Each mode of
definite canonical momenta k_+ experiences pair creation at the instant when
its kinetic momentum p_+=k_+ - e A_-(x_+) vanishes, at which point operators
from the surface at x_- =-\infty play a crucial role. Our formalism permits a
more explicit and complete derivation of the rate of particle production than
is usually given. We show that the system can be understood as the infinite
boost limit of the analogous problem of an electric field which is homogeneous
on surfaces of constant x^0.


title: Schwinger's Propagator Is Only A Green's Function

abstract:
  Schwinger used an analytic continuation of the effective action to correctly
compute the particle production rate per unit volume for QED in a uniform
electric field. However, if one simply evaluates the one loop expectation value
of the current operator using his propagator, the result is zero! We analyze
this curious fact from the context of a canonical formalism of operators and
states. The explanation turns out to be that Schwinger's propagator is not
actually the expectation value of the time-ordered product of field operators
in the presence of a time-independent state, although it is of course a Green's
function. We compute the true propagator in the presence of a state which is
empty at $x_+ = 0$ where $x_+ \equiv (x^0+x^3)/\sqrt{2}$ is the lightcone
evolution parameter. Our result can be generalized to electric fields which
depend arbitrarily on $x_+$.


title:
Observable interactions of quintessence with ordinary matter and
  neutrinos

abstract:
  For any realistic theory of quintessence that allows for a violation of the
equivalence principle (VEP), we study the experimental constraints on such
theories coming from ordinary matter as well as neutrinos. We discuss and
compare constraints from two basically different (extra) contributions to
differences of fermion masses: one is due to the vacuum expectation value (vev)
of quintessence, and the other is based on a quintessence-exchange graph at
finite temperature/density.


title: The semileptonic decays of the B_c meson

abstract:
  We study the semileptonic transitions B_c to \eta_c, J/\psi, D, D^*, B, B^*,
B_s, B_s^* in the framework of a relativistic constituent quark model. We use
experimental data on leptonic J/\psi decay, lattice and QCD sum rule results on
leptonic B_c decay, and on radiative \eta_c transitions to adjust the quark
model parameters. We compute all form factors of the above semileptonic
B_c-transitions and give predictions for various semileptonic B_c decay modes
including their \tau-modes when they are kinematically accessible. The
implications of heavy quark symmetry for the semileptonic decays are discussed
and are shown to be manifest in our explicit relativistic quark model
calculation. A comparison of our results with the results of other calculations
is performed.


title:
Standard Model correlations between K -> \pi \nu \bar\nu decays and
  observables in B Physics

abstract:
  Including the recent preliminary results of BaBar and BELLE experiments, we
update the currently allowed intervals for various CKM parameters: $\bar\rho$,
$\bar\eta$, $\sin2\beta$, $\sin2\alpha$, $\sin^2\gamma$. We also update the SM
prediction for the rates of the $K_L \to \pi^0 \nu \bar\nu$ and $K^+ \to \pi^+
\nu \bar\nu$ decays, their ratio $a_{\pi \nu \bar\nu}$, as well as for certain
observables related to $B$ Physics like the CP asymmetries $a_{\psi K_S}$ in
$B^0_d \to J/\psi K_S$ and $a_{\psi \phi}$ in $B^0_s \to J/\psi \phi$ or the
mass differences $\Delta m_q$ ($q=d,s$) in the $B^0_q-\bar B^0_q$ systems. We
investigate the correlations between them. The strongest correlations are
between i) $a_{\pi \nu \bar\nu}$ and $a_{\psi K_S}$, ii) $\BR(K^+ \to \pi^+ \nu
\bar\nu)$ and $\Delta m_d/\Delta m_s$ and iii) $\BR(K_L \to \pi^0 \nu \bar\nu)$
and $a_{\psi \phi}$. These correlations are likely to be violated in the
presence of New Physics and therefore provide stringent tests of the Standard
Model.


title: Three loop MSbar tensor current anomalous dimension in QCD

abstract:
  The anomalous dimensions of the general flavour non-singlet quark bilinear
currents \psi \gamma^{[\mu_1} ... \gamma^{\mu_n]} \psi are computed at three
loops in quantum chromodynamics in the minimal subtraction scheme. The
dimension of the tensor current emerges for the case n = 2 and the anomalous
dimension for the general flavour singlet current is also discussed.


title:
Combining QCD Matrix Elements at Next-to-Leading Order with Parton
  Showers in Electroproduction

abstract:
  We present a method to combine next-to-leading order (NLO) matrix elements in
QCD with leading logarithmic parton showers by applying a suitably modified
version of the phase-space-slicing method. The method consists of subsuming the
NLO corrections into a scale-dependent phase-space-slicing parameter, which is
then automatically adjusted to cut out the leading order, virtual, soft and
collinear contributions in the matrix element calculation. In this way a
positive NLO weight is obtained, which can be redistributed by a parton shower
algortihm. As an example, we display the method for single-jet inclusive cross
sections at O(alpha_s) in electroproduction. We numerically compare the
modified version of the phase-space-slicing method with the standard approach
and find very good agreement on the percent level.


title: Chiral Transition and Baryon-number Susceptibility

abstract:
  We discuss the baryon-number susceptibility $\chi_B$ and related topics which
include the density fluctuations around the critical point of the chiral
transition at finite temperature $T$ and baryon density $\rho_B$.
Phenomenological implications of the density fluctuations near the first-order
chiral transition at finite density are also discussed.


title: Three-Body Decays of SUSY Particles

abstract:
  We analyze the decays of charginos, neutralinos, gluinos and the first/second
generation squarks in the Minimal Supersymmetric extension of the Standard
Model, focusing on the three-body decays in scenarios where the ratio $\tan
\beta$ of vacuum expectation values of the two Higgs doublet fields is large.
We show that the three-body decays of the next-to-lightest neutralinos
(lightest charginos) into $b\bar{b},\tau^+\tau^-$ ($\tau \nu$) final states,
where third generation sfermion and Higgs boson exchange diagrams play an
important role, are dominant. Furthermore, we show that decays of gluinos into
$b\bar{b}$ final states and squark decays into lighter sbottoms through gluino
exchange can also have sizeable branching fractions, especially in scenarios
where the soft SUSY breaking gaugino mass parameters are not unified at the GUT
scale.


title: Deconfinement through Chiral Symmetry Restoration in Two-Flavour QCD

abstract:
  We propose that in QCD with dynamical quarks, colour deconfinement occurs
when an external field induced by the chiral condensate strongly aligns the
Polyakov loop. This effect sets in at the chiral symmetry restoration
temperature T-chi and thus makes deconfinement and chiral symmetry restoration
coincide. The predicted singular behaviour of Polyakov loop susceptibilities at
T-chi is shown to be supported by finite temperature lattice calculations.


title: Neutrino masses and the baryon asymmetry

abstract:
  Due to sphaleron processes in the high-temperature symmetric phase of the
standard model the cosmological baryon asymmetry is related to neutrino
properties. For hierarchical neutrino masses, with $B-L$ broken at the
unification scale $\Lambda_{GUT}\sim 10^{16} $GeV, the observed baryon
asymmetry $n_B/s \sim 10^{-10}$ can be naturally explained by the decay of
heavy Majorana neutrinos. We illustrate this mechanism with two models of
neutrino masses, consistent with the solar and atmospheric neutrino anomalies,
which are based on the two symmetry groups $SU(5)\times U(1)_F$ and
$SU(3)_c\times SU(3)_L\times SU(3)_R\times U(1)_F$.
  We also review related cosmological bounds on Majorana neutrino masses and
the use of Boltzmann equations.


title: Geometric Bounds on Kaluza-Klein Masses

abstract:
  We point out geometric upper and lower bounds on the masses of bosonic and
fermionic Kaluza-Klein excitations in the context of theories with large extra
dimensions. The characteristic compactification length scale is set by the
diameter of the internal manifold. Based on geometrical and topological
considerations, we find that certain choices of compactification manifolds are
more favoured for phenomenological purposes.


title: Supersymmetric Large Extra Dimensions Are Small and/or Numerous

abstract:
  Recently, a scenario has been proposed in which the gravitational scale could
be as low as the TeV scale, and extra dimensions could be large and detectable
at the electroweak scale. Although supersymmetry is not a requirement of this
scenario, it is nevertheless true that its best-motivated realizations arise in
supersymmetric theories (like M theory). We argue here that supersymmetry can
have robust, and in some instances fatal, implications for the expected
experimental signature for TeV-scale gravity. The signature of the
supersymmetric version of the scenario differs most dramatically from what has
been considered in the literature because mass splittings within the gravity
supermultiplet in these models are extremely small, implying in particular the
existence of a very light spin-one superpartner for the graviton. We compute
the implications of this graviphoton, and show that it can acquire
dimension-four couplings to ordinary matter which can strongly conflict with
supernova bounds.


title: Is the electric charge conserved in brane world?

abstract:
  We discuss whether electric charge conservation may not hold in
four-dimensional world in models with infinite extra dimensions, i.e., whether
escape of charged particles from our brane is consistent with effectively
four-dimensional electrodynamics on the brane. We introduce a setup with photon
localized on the brane and show that charge leakage into extra dimension is
allowed within this setup. The electric field induced on the brane by escaping
charge does not obey four-dimensional Maxwell's equations; this field gradually
disappears in a causal way. We also speculate on the possibility of the escape
of colored particles and formation of colorless free quark states on the brane.


title: Two-Fermion Production in Electron-Positron Collisions

abstract:
  This report summarizes the results of the two-fermion working group of the
LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the
theoretical calculations of the two fermion production process in the
electron-positron collision at LEP2 center of the mass energies are reported.
The Bhabha process and the production of muon, tau, neutrino and quark pairs is
covered. On the basis of comparison of various calculations, theoretical
uncertainties are estimated and compared with those needed for the final LEP2
data analysis. The subjects for the further studies are identified.


title: Short-Baseline Neutrino Oscillations at a Neutrino Factory

abstract:
  Within the framework of three-neutrino and four-neutrino scenarios that can
describe the results of the LSND experiment, we consider the capabilities of
short baseline neutrino oscillation experiments at a neutrino factory. We find
that, when short baseline ($L \alt 100$ km) neutrino factory measurements are
used together with other accelerator-based oscillation results, the complete
three-neutrino parameter space can best be determined by measuring the rate of
$\nu_e \to \nu_\tau$ oscillations, and measuring CP violation with either
$\nu_e \to \nu_\mu$ or $\nu_\mu \to \nu_\tau$ oscillations (including the
corresponding antineutrino channels). With measurements of CP violation in both
$\nu_e \to \nu_\mu$ and $\nu_\mu \to \nu_\tau$ it may be possible to
distinguish between the three- and four-neutrino cases.


title: QCD Instantons and the Soft Pomeron

abstract:
  We study the role of semi-classical QCD vacuum solutions in high energy
scattering by considering the instanton contribution to hadronic cross
sections. We propose a new type of instanton-induced interactions (``instanton
ladder'') that leads to the rising with energy hadronic cross section of Regge
type (the Pomeron). We argue that this interaction may be responsible for the
structure of the soft Pomeron. The intercept is calculated. It has a
non-analytic dependence on the strong coupling constant, allowing a
non-singular continuation into the non-perturbative region. We derive the
Pomeron trajectory, which appears to be approximately linear in some range of
(negative) momentum transfer t, but exhibits a curvature at small t. Possible
role of instantons in multiparticle production is also discussed.


title:
Bound-state effects in \mu^+ e^- \to \gamma\gamma and \bar{B}^{0}_s \to
  \gamma\gamma decays

abstract:
  We demonstrate that in the double-radiative decays of heavy-light QED and QCD
atoms, \mu^{+} e^{-} \to \gamma\gamma and \bar{B}^{0}_{s} \to \gamma\gamma,
there is a contribution coming from operators that vanish on the free-quark
mass shell. This off-shell effect is suppressed with respect to the effect of
the well known flavour-changing magnetic-moment operator by the bound-state
binding factor. Accordingly, the negligible off-shellness of the weakly bound
QED atoms becomes important for strongly bound QCD atoms. We present this
effect in two different model-approaches to QCD, one of them enabling us to
keep close contact to the related effect in QED.


title: Quark level linear \sigma model (L\sigma M) via loop graphs

abstract:
  First, the L\sigma M is nonperturbatively solved via loop-order gap
equations. Then the Nambu-Goldstone theorem (NGT) is expressed in L\sigma M
language. Next, the Lee null tadpole sum for this SU(2) L\sigma M theory is
shown to require N_c = 3. Then L\sigma M s-wave chiral cancellations are
studied in tree-and in loop-order. Also, vector meson dominance (VMD) is shown
to follow from this L\sigma M. Next, the scalar nonet is studied in the
infinite momentum frame (IMF). Finally, the L\sigma M is suggested as the
infrared limit of nonperturbative QCD.


title:
Further studies on relic neutrino asymmetry generation I: the adiabatic
  Boltzmann limit, non-adiabatic evolution, and the classical harmonic
  oscillator analogue of the quantum kinetic equations

abstract:
  We demonstrate that the relic neutrino asymmetry evolution equation derived
from the quantum kinetic equations (QKEs) reduces to the Boltzmann limit that
is dependent only on the instantaneous neutrino number densities, in the
adiabatic limit in conjunction with sufficient damping. An original physical
and/or geometrical interpretation of the adiabatic approximation is given,
which serves as a convenient visual aid to understanding the sharply
contrasting resonance behaviours exhibited by the neutrino ensemble in opposing
collision regimes. We also present a classical analogue for the evolution of
the difference in $\nu_{\alpha}$ and $\nu_s$ number densities which, in the
Boltzmann limit, is akin to the behaviour of the generic reaction $A
\rightleftharpoons B$ with equal forward and reverse reaction rate constants. A
new characteristic quantity, the matter and collision-affected mixing angle of
the neutrino ensemble, is identified here for the first time. The role of
collisions is revealed to be twofold: (i) to wipe out the inherent
oscillations, and (ii) to equilibrate the $\nu_{\alpha}$ and $\nu_s$ number
densities in the long run. Studies on non-adiabatic evolution and its possible
relation to rapid oscillations in lepton number generation also feature, with
the introduction of an adiabaticity parameter for collision-affected
oscillations.


title:
Further studies on relic neutrino asymmetry generation II: a rigorous
  treatment of repopulation in the adiabatic limit

abstract:
  We derive an approximate relic neutrino asymmetry evolution equation that
systematically incorporates repopulation processes from the full quantum
kinetic equations (QKEs). It is shown that in the collision dominant epoch, the
said equation reduces precisely to the expression obtained previously from the
static/adiabatic approximation. The present treatment thus provides a rigorous
justification for the seemingly incongruous assumptions of a negligible
repopulation function and instantaneous repopulation sometimes employed in
earlier works.


title:
(3+1)-dimensional relativistic hydrodynamical expansion of hot and dense
  matter in ultra-relativistic nuclear collision

abstract:
  A full (3+1)-dimensional calculation using the Lagrangian hydrodynamics is
proposed for relativistic nuclear collisions. The calculation enables us to
evaluate anisotropic flow of hadronic matter which appears in non-central
and/or asymmetrical relativistic nuclear collisions. Applying hydrodynamical
calculations to the deformed uranium collisions at AGS energy region, we
discuss the nature of space-time structure and particle distributions in
detail.


title: Evolution of DIS structure functions at small x

abstract:
  A short review of recent theoretical results on the Deep Inelastic Scattering
is presented.


title:
Impact of the W boson decay width on photon bremsstrahlung accompanying
  W pair production

abstract:
  The bremsstrahlung spectrum of photons accompanying $W$ pair production
depends on the decay width of the unstable $W$ bosons. The dependence arises
from the interference between emission at different stages of the production
and decay process. We present a quantitative discussion of this effect, and
consider the implications for measurements at LEP2 and LC energies.


title: Non-perturbative effects in the W and Z transverse momentum distribution

abstract:
  We use the "dispersive method" to investigate non-perturbative effects in the
transverse momentum distribution of vector bosons produced in p-pbar
collisions. The assumption of a non-perturbative modification to the running
coupling at low scales leads to additional contributions in impact parameter
space proportional to -b^2 log Q^2 and -b^2. Our results, which we expect to be
valid provided tau is not close to 1, are shown to account for a substantial
proportion of the total non-perturbative contribution extracted from data.


title:
Examination of direct-photon and pion production in proton-nucleon
  collisions

abstract:
  We present a study of inclusive direct-photon and pion production in hadronic
interactions, focusing on a comparison of the ratio of gamma/pi0 yields with
expectations from next-to-leading order perturbative QCD (NLO pQCD). We also
examine the impact of a phenomenological model involving k_T smearing (which
approximates effects of additional soft-gluon emission) on absolute predictions
for photon and pion production and their ratio.


title:
Geometric scaling for the total gamma^* p cross section in the low x
  region

abstract:
  We observe that the saturation model of deep inelastic scattering, which
successfully describes inclusive and diffractive data at small x, predicts a
geometric scaling of the total gamma^* p cross section in the region of small
Bjorken variable x. The geometric scaling in this case means that the cross
section is a function of only one dimensionless variable tau = Q^2 R_0^2(x),
where the function R_0(x) (called saturation radius) decreases with decreasing
x. We show that the experimental data from HERA in the region x<0.01 confirm
the expectations of this scaling over a very broad region of Q^2. We suggest
that the geometric scaling is more general than the saturation model.


title: The KM phase in semi-realistic heterotic orbifold models

abstract:
  In string-inspired semi-realistic heterotic orbifolds models with an
anomalous $U(1)_X$, a nonzero Kobayashi-Masakawa (KM) phase is shown to arise
generically from the expectation values of complex scalar fields, which appear
in nonrenormalizable quark mass couplings. Modular covariant nonrenormalizable
superpotential couplings are constructed. A toy $Z_3$ orbifold model is
analyzed in some detail. Modular symmetries and orbifold selection rules are
taken into account and do not lead to a cancellation of the KM phase. We also
discuss attempts to obtain the KM phase solely from renormalizable
interactions.


title: Theoretical Issues in the Tevatron Era

abstract:
  The Fermilab Tevatron's operation for fixed-target physics from its start in
1983 until the end of fixed-target running in 2000 was marked by extraordinary
peoductivity and variety. Some of the changing theoretal issues associated with
this program are reviewed.


title: Searching for the Lightest Neutralino at Fixed Target Experiments

abstract:
  Most ongoing supersymmetry searches have concentrated on the high-energy
frontier. High-intensity fixed target beamlines, however, offer an opportunity
to search for supersymmetric particles with long lifetimes and low
cross-sections in regions complementary to the ones accessible to collider
experiments. In this paper, we consider R-parity violating supersymmetry
searches for the lightest neutralino and use the NuTeV experiment as an example
for the experimental sensitivity which can be achieved.


title: Dimension-eight Operators in the Weak OPE

abstract:
  We expose a potential flaw in standard treatments of weak decay amplitudes,
including that of epsilon'/epsilon. We show that (contrary to conventional
wisdom) dimension-eight operators do contribute to weak amplitudes, at order
G_F alpha_s and without 1/M_W^2 suppression. We demonstrate the existence of
these operators with a simple weak hamiltonian and proceed to discuss their
contribution in a general context. We estimate the effect of dimension-eight
operators to be at the 100% level in a sum rule determination of the operator
O_7 for mu = 1.5 GeV, suggesting presently available values of mu are too low
to justify neglect of these effects.


title: The Renormalization Group Improvement of the QCD Static Potentials

abstract:
  We resum the leading ultrasoft logs of the singlet and octet static QCD
potentials within potential NRQCD. We then obtain the complete three-loop
renormalization group improvement of the singlet QCD static potential. The
discrepancies between the perturbative evaluation and the lattice results at
short distances are slightly reduced.


title: Parton-Based Gribov-Regge Theory

abstract:
  We present a new parton model approach for hadron-hadron interactions and, in
particular, for the initial stage of nuclear collisions at very high energies
(RHIC, LHC and beyond). The most important aspect of our approach is a
self-consistent treatment, using the same formalism for calculating cross
sections and particle production, based on an effective, QCD-inspired field
theory, where many of the inconsistencies of presently used models will be
avoided.
  In addition, we provide a unified treatment of soft and hard scattering, such
that there is no fundamental cutoff parameter any more defining an artificial
border between soft and hard scattering.
  Our approach cures some of the main deficiencies of two of the standard
procedures currently used: the Gribov-Regge theory and the eikonalized parton
model. There, cross section calculations and particle production cannot be
treated in a consistent way using a common formalism. In particular, energy
conservation is taken care of in case of particle production, but not
concerning cross section calculations. In addition, hard contributions depend
crucially on some cutoff, being divergent for the cutoff being zero. Finally,
in case of several elementary scatterings, they are not treated on the same
level: the first collision is always treated differently than the subsequent
ones. All these problems are solved in our new approach.


title: Pseudovector mesons, hybrids and glueballs

abstract:
  We consider glueball- (hybrid) meson mixing for the low-lying four
pseudovector states. The h_1'(1380) decays dominantly to K*K with some presence
in rho pi and omega eta. The newly observed h_1(1600) has a D- to S-wave width
ratio to omega eta which makes its interpretation as a conventional meson
unlikely. We predict the decay pattern of the isopartner conventional or hybrid
meson b_1(1650). A notably narrow s sbar partner h_1'(1810) is predicted.


title:
Single Sbottom/Scharm Production at HERA in an R-Parity Breaking
  Supersymmetric Model

abstract:
  We investigate the production process of the single scalar bottom quark
(sbottom) and scalar charm quark (scharm) at HERA. The sbottom and scharm could
be produced via an R-parity breaking interactions $\lambda'_{123} \neq 0$ in
the Minimal Supersymmetric Standard Model (MSSM). These processes give a slight
excess in the invariant mass $M_{eq}$ distribution of the high $Q^2$ deep
inelastic scattering for sufficiently heavy gauginos and the scalar top (stop).
For the light gauginos and stop, it is shown that the tagging of $b/c$-quarks
and charged leptons with high transverse energies will be indispensable to
search for the processes.


title:
Transverse momentum distributions and their forward- backward
  correlations in the percolating colour string approach

abstract:
  The forward-backward correlations in the $p_T$ distributions, which present a
clear signature of non-linear effects in particle production, are studied in
the model of percolating colour strings. Quantitative predictions are given for
these correlations at SPS, RHIC and LHC energies. Interaction of strings also
naturally explains the flattening of $p_T$ distributions and increase of
$<p_T>$ with energy and atomic number for nuclear collisions


title: Scrutinizing LSP Dark Matter at the LHC

abstract:
  We show that LHC experiments might well be able to determine all the
parameters required for a prediction of the present density of thermal LSP
relics from the Big Bang era. If the LSP is an almost pure bino we usually only
need to determine its mass and the mass of the SU(2) singlet sleptons. This
information can be obtained by reconstructing the cascade $\tilde{q}_L \to
\tilde{\chi}_2^0 q \to \tilde{\ell}_R \ell q \to \tilde{\chi}_1^0 \ell^+ \ell^-
q$. The only requirement is that $m_{\tilde{\ell}_R} < m_{\tilde{\chi}_2^0}$,
which is true for most of the cosmologically interesting parameter space. If
the LSP has a significant higgsino component, its predicted thermal relic
density is smaller than for an equal--mass bino. We show that in this case
squark decays also produce significant numbers of $\tilde{\chi}_4^0$ and
$\tilde{\chi}_2^\pm$. Reconstructing the corresponding decay cascades then
allows to determine the higgsino component of the LSP.


title: Role of relativistic kinematics in describing two-quark systems

abstract:
  An attempt to incorporate relativistic kinematics in the description of light
quark systems is made. It seems that the way of such incorporation along the
suggestion expressed by R. Gaida and his collaborators is very promising.
Comparison of these results with the experimental data concerning boson mass
spectrum shows that this approach is among the best theoretical interpretation
of the data.


title:
On the production of a lepton pair in the collision of ultrarelativistic
  neutral particle with nonzero magnetic moment with nuclei

abstract:
  Explicit formulas which describe muon pair production in reaction $\gamma\nu
\to \mu^+ \mu^- \nu$ through neutrino magnetic moment are obtained and used to
derive in the leading approximation cross section of muon pair production in
$\nu N$-scattering due to neutrino magnetic moment. This cross section appears
to be proportional to $\log^4 E_{\nu}$. Comparison with experimental data on
tridents production provides an upper bound $\mu_{\nu_{\mu}} < 4*10^{-8}
\mu_B$, which is approximately two orders of magnitude weaker than that from
$\nu_{\mu}e$ elastic scattering data.


title:
On the masses, branching ratios, and full widths of heavy rho', rho''
  and omega', omega'' resonances

abstract:
  Based on the previous and recent fits of multiple data on the reactions of
e^+e^- annihilation, tau lepton decay, and the reaction K^-p -> pi^+pi^-
Lambda, the magnitude of the branching ratios and total widths of the isovector
rho', rho'', and the isoscalar omega', omega'' resonances are calculated. Some
topics on the spectroscopy of the rho(1450) and omega(1420) states are
discussed.


title:
Sparticle spectrum and dark matter in type I string theory with an
  intermediate scale

abstract:
  The supersymmetric particle spectrum is calculated in type I string theories
formulated as orientifold compactifications of type IIB string theory. A string
scale at an intermediate value of $10^{11}-10^{12}$ GeV is assumed and extra
vector-like matter states are introduced to allow unification of gauge coupling
constants to occur at this scale. The qualitative features of the spectrum are
compared with Calabi-Yau compactification of the weakly coupled heterotic
string and with the eleven dimensional supergravity limit of $M$-theory. Some
striking differences are observed. Assuming that the lightest neutralino
provides the dark matter in the universe, further constraints on the sparticle
spectrum are obtained. Direct detection rates for dark matter are estimated.


title: Predicting D -> sigma pi

abstract:
  We examine the D -> sigma pi amplitude through a constituent quark-meson
model, incorporating heavy quark and chiral symmetries, finding a good
agreement with the recent E791 data analysis of D -> 3 pi via sigma.


title: Final State Interactions in Kaon Decays

abstract:
  We quantify the important effect of strong final state interactions in the
weak $K\to 2\pi$ amplitudes, using the measured $\pi$-$\pi$ phase shifts with
J=0 and $I=0,2$. The main results of this analysis, with their implications for
$\epsilon'/\epsilon$ and the $\Delta I =1/2$ rule, have been already presented
in a previous paper [1]. Here we provide a detailed formal derivation of those
results and further discuss the Standard Model prediction of
$\epsilon'/\epsilon$.


title: Phase Transitions in QCD

abstract:
  At high temperatures or densities, hadronic matter shows different forms of
critical behaviour: colour deconfinement, chiral symmetry restoration, and
diquark condensation. I first discuss the conceptual basis of these phenomena
and then consider the description of colour deconfinement in terms of symmetry
breaking, through colour screening and as percolation transition.


title:
The 't Hooft interaction at finite T and $\mu$: Beyond the mean field
  theory

abstract:
  We use the N-quantum approach (NQA) to quantum field theory to construct a
solution of the two flavor effective instanton induced `t Hooft interaction
model valid for any temperature (T) and chemical potential ($\mu$) beyond the
mean field theory. The model contains only the $\bar{q}q$ channels. In
constructing this solution we calculate the masses, widths and coupling
constants of bound $\sigma$ and resonant color $\bar{3}$ scalar diquark states.
We find that the chemical potential induced by the interaction cancel exactly
for all values of T in contrast to the Nambu-Jona-Lasinio model. Our method can
also be extended to include the qq channels in the model Lagrangian and we
discuss how the NQA can be used to study the properties of bound diquark states
at finite T and $\mu$.


title: On Sub-Millimeter Forces From Extra Dimensions

abstract:
  We show that in theories with large extra dimensions forces mediated by a
bulk dilaton and bulk gauge fields may be parametrically (exponentially) weaker
than gravity due to the suppression of their wave-functions on a brane. This is
the case when dilaton gets stabilized by certain strongly coupled dynamics on
the brane, or the bulk gauge symmetries are spontaneously broken by the Higgs
mechanism on the worldvolume. At distances smaller than the size of a largest
extra dimension these particles produce the force-law which decreases with
distance faster than high-dimensional gravity. For a millimeter size extra
dimensions predicted deviations are in the range which may be detected in
sub-millimeter gravity measurements.


title: Disentangling the Imaginary-Time Formalism at Finite Temperature

abstract:
  We rewrite the imaginary-time formalism of finite temperature field theory in
a form that all graphs used in calculating physical processes do not have any
loops. Any production of a particle from a heat bath which is itself not
thermalized or the decay and absorption of a similar particle in the bath is
expressed entirely in terms of the sum of particle interaction processes. These
are themselves very general in meaning. They can be straight forward
interactions or the more subtle and less well-known purely interference
processes that do not have a counter part in the vacuum.