title: CPT and Lorentz Symmetry in Hydrogen and Antihydrogen

abstract:
  Possibilities for observing signals of CPT and Lorentz violation in the
spectroscopy of hydrogen and antihydrogen are considered. We show that
transitions between the c and d hyperfine sublevels in the 1S state can exhibit
theoretically detectable effects that would be unsuppressed by powers of the
fine-structure constant. This transition may therefore offer some advantages
over 1S-2S two-photon spectroscopy.


title: Theta-Induced Electric Dipole Moment of the Neutron via QCD Sum Rules

abstract:
  Using the QCD sum rule approach, we calculate the electric dipole moment of
the neutron induced by a vacuum theta--angle to approximately 40-50% precision,
d_n = 2.4 x 10^{-16} \theta e.cm. Combined with the new experimental bound,
this translates into the limit |\theta|< 3 x 10^{-10}.


title: On Limitations of T Invariance in K Decays

abstract:
  Data from the CPLEAR collaboration coupled with the assumption that the
Bell-Steinberger relation holds have provided {\em direct} evidence for
\ot~violation. In this note we investigate what we can say about \ot~violation
{\em without} such an assumption.
  We show that both the modulus and the phase of $\eta_{+-}$ can be reproduced
with \ot~{\em invariant} dynamics through finetuning \cpt~breaking. The large
\ot~odd correlation observed by the KTeV collaboration in $K_L \to \pi ^+\pi ^-
e^+ e^-$ thus does not yield direct evidence for \ot~violation. In such a world
the phase of $\frac{\epsilon'}{\epsilon}$ is $\delta_2-\delta_0-\phi_{SW}\sim
-(85.5\pm 4)^\circ$. Also, $K^{\pm} \to \pi ^{\pm} \pi ^0$ could exhibit a
\cpt~asymmetry of up to few$\times 10^{-3}$ without upsetting any known bound.


title: D-branes, String Cosmology and Large Extra Dimensions

abstract:
  D-branes are fundamental in all scenarios where there are large extra
dimensions and the string scale is much smaller than the four-dimensional
Planck mass. We show that this current picture leads to a new approach to
string cosmology where inflation on our brane is driven by the large extra
dimensions and the issue of the graceful exit becomes inextricably linked to
the problem of the stabilization of the extra dimensions, suggesting the
possibility of a common solution. We also show that branes may violently
fluctuate along their transverse directions in curved spacetime, possibly
leading to a period of brane-driven inflation. This phenomenon plays also a
crucial role in many other cosmological issues, such as the smoothing out of
the cosmological singularities and the generation of the baryon asymmetry on
our three brane.


title: Semi-inclusive deep inelastic lepton scattering off complex nuclei

abstract:
  It is shown that in semi-inclusive deep inelastic scattering (DIS) of
electrons off a complex nucleus A, the detection, in coincidence with the
scattered electron, of a nucleus (A-1) in the ground state, as well as of a
nucleon and a nucleus (A-2), also in the ground state, may provide unique
information on several long standing problems, such as : i) the nature and the
relevance of the final state interaction in DIS; ii) validity of the spectator
mechanism in DIS; iii) the medium induced modifications of the nucleon
structure function; iv) the origin of the EMC effect.


title: QCD Aspects of Hadron Physics

abstract:
  Several topics in hadron physics at different scales of resolution are
discussed. First, deep-inelastic scattering from nucleons and nuclei is viewed
in a light-cone coordinate space picture. Then the smooth transition from
parton to hadron degrees of freedom is demonstrated by using a generalized
Q^2-dependent polarizabilities of the nucleon. Turning to low energy QCD we
summarize recent developments related to the role of strange quarks in Chiral
SU(3) Dynamics, a non-perturbative coupled channel approach to hadronic
processes. Finally we elaborate on a unification of QCD Sum Rules with aspects
of spontaneous chiral symmetry breaking in the analysis of quark-antiquark
excitations of the condensed QCD vacuum and in nuclear matter.


title: Upper Bound on the Lightest Higgs Mass in Supersymmetric Theories

abstract:
  The problem of the lightest Higgs boson mass in the next-to-minimal
supersymmetric standard model (NMSSM) is investigated. Assuming the validity of
the perturbation theory up to unification scales and using the recent
experimental results for the top quark mass, the restrictions on the NMSSM
coupling constants are obtained. These restrictions are used to make the
predictions for the lightest Higgs mass, which are compared to those of the
minimal supersymmetric standard model (MSSM).


title: Oscillations of the mixed pseudo--Dirac neutrinos

abstract:
  Oscillations of three pseudo--Dirac flavor neutrinos $\nu_e, \nu_\mu,
\nu_\tau$ are considered: $0 < m^{(L)} = m^{(R)} \ll m^{(D)}$ for their
Majorana and Dirac masses taken as universal before family mixing. The actual
neutrino mass matrix is assumed to be the tensor product $ M^{(\nu)} \otimes
{(\begin{array}{cc} \lambda^{(L)} & 1 1 & \lambda^{(R)} \end{array})}$, where
$M^{(\nu)}$ is a neutrino family mass matrix ($ M^{(\nu) \dagger} = M^{(\nu)}$)
and $\lambda^{(L,R)} = m^{(L,R)}/m^{(D)}$. The $ M^{(\nu)}$ is tried in a form
proposed previously for charged leptons $e, \mu, \tau$ for which it gives
$m_\tau = 1776.80$ MeV versus $m^{exp}_\tau = 1777.05^{+0.29}_{-0.20}$ MeV
(with the experimental values of $m_e$ and $m_\mu$ used as inputs). However, in
contrast to the charged -lepton case, in the neutrino case its off-diagonal
entries dominate over diagonal. Then, it is shown that three neutrino effects
(the deficits of solar $\nu_e$'s and atmospheric $\nu_\mu$'s as well as the
possible LSND excess of $\nu_e$'s in accelerator $\nu_\mu$ beam) can be
explained by neutrino oscillations though, alternatively, the LSND effect may
be eliminated (by a parameter choice). Atmospheric $\nu_\mu$'s oscillate
dominantly into $\nu_\tau$'s, while solar $\nu_e$'s -- into (automatically
existing) Majorana sterile counterparts of $\nu_e$'s.


title: Comment on the heavy-->light form factors

abstract:
  We propose a simple parametrization for the form factors in heavy to light
decays which satisfies the heavy quark scaling laws and avoids introducing the
explicit "dipole" form. The illustration is provided on the set of lattice data
for B -> pi, semileptonic decay. The resulting shape of the form factor also
agrees with the QCD sum rule predictions.


title:
Higgs production in association with squark pairs in the Minimal
  Supersymmetric Standard Model at future hadron colliders

abstract:
  We study neutral and charged Higgs boson production in association with stop
and sbottom squarks at the Large Hadron Collider, within the Supergravity
inspired Minimal Supersymmetric Standard Model. The phenomenological relevance
of such reactions is twofold. Firstly, they constitute a novel production
mechanism of Higgs particles, either through a decay of a heavier (anti)squark
into a lighter one or via a Higgs bremsstrahlung process. Secondly, their
production rates are extremely sensitive to the values assumed by the five
input parameters of the model, this possibly allowing one to put stringent
constraints on the latter. After an exhaustive scan of the parameter space, we
find that the majority of such processes could be detectable at high
luminosity, provided tan(beta) is large, tan(beta) > 30 (except in the case of
\tilde{t}_1\tilde{t}_1^* h and \tilde{t}_1\tilde{t}_2^* h final states, whose
detection is also possible for smaller values), that the universal soft
Supersymmetric breaking masses are in the ranges M_0 < 500 GeV and M_{1/2} <
220 GeV, and that the trilinear couplings are negative, A_0 < 0. We also point
out some sizable decay signatures and discuss their Standard Model (SM)
backgrounds. Finally, we derive compact analytical formulae of the
corresponding scattering matrix elements.


title:
The Role of Incident Parton Transverse Momenta in Heavy Quark
  Hadroproduction

abstract:
  The conventional NLO parton model is enough for the description of total
cross sections and one-particle distributions. In the case of two-particle
correlations, the collinear approximation has failed, and it is necessary to
account for the transverse momenta of initial partons. The different
possibilities to do this are discussed.


title: A structural model of quarks and leptons

abstract:
  A model is proposed in which quarks, leptons and perhaps gauge bosons are
composites of magnetically charged rishons T(q=1/3) and V(q=0) with magnetic
charges g=(1,2,-3)g0. Structural formulas of composite particles and their
interactions are given, with the binding lines representing magnetic fields.
Higher generations are produced by adding rishon-antirishon pairs with the
three different magnetic charges.


title:
Flux Tube Zero-Point Motion, Hadronic Charge Radii, and Hybrid Meson
  Production Cross Sections

abstract:
  Flux tube zero-point motion produces quark displacements transverse to the
flux tube which make significant contributions to hadronic charge radii. In
heavy quark systems, these contributions can be related by Bjorken's sum rule
to the rates for semileptonic decay to hybrid mesons. This connection can be
generalized to other leptoproduction processes, where transverse contributions
to elastic form factor slopes are related to the cross sections for the
production of the associated hybrid states. I identify the flux tube overlap
integral responsible for these effects as the strong QCD analogue of the
Sudakov form factor of perturbative QCD.


title: Inflation from Extra Dimensions

abstract:
  The radial mode of n extra compact dimensions (the radion, b) can cause
inflation in theories where the fundamental gravity scale, M, is smaller than
the Planck scale M_P. For radion potentials V(b) with a simple polynomial form,
to get the observed density perturbations, the energy scale of V(b) must
greatly exceed M ~ 1 TeV: V(b)^{1/4} = M_v ~ 10^{-4} M_P. This gives a large
radion mass and reheat temperature ~ 10^9 GeV, thus avoiding the moduli
problem. Such a value of M_v can be consistent with the classical treatment if
the new dimensions started sufficiently small. A new possibility is that b
approaches its stable value from above during inflation. The same conclusions
about M_v may hold even if inflation is driven by matter fields rather than by
the radion.


title: K* nucleon hyperon form factors and nucleon strangeness

abstract:
  A crucial input for recent meson hyperon cloud model estimates of the nucleon
matrix element of the strangeness current are the nucleon-hyperon-K* (NYK*)
form factors which regularize some of the arising loops. Prompted by new and
forthcoming information on these form factors from hyperon-nucleon potential
models, we analyze the dependence of the loop model results for the
strange-quark observables on the NYK* form factors and couplings. We find, in
particular, that the now generally favored soft N-Lambda-K* form factors can
reduce the magnitude of the K* contributions in such models by more than an
order of magnitude, compared to previous results with hard form factors. We
also discuss some general implications of our results for hadronic loop models.


title:
Out-going Muon Flux from Neutralino Annihilation in the Sun and the
  Earth in Supergravity Unification

abstract:
  Predictions for the out-going muon fluxes from the annihilation of
neutralinos in the center of the Sun and the Earth in supergravity unification
are given. Effects of uncertainties of the input data are analysed. It is shown
that the out-going muon flux measurements from the Sun and the Earth are
complementary, with the Earth providing a larger flux for low values of fine
tuning and the Sun providing a larger flux for high values of fine tuning, and
that only a combination of the two can compete favorably with the direct
detection measurements. The predictions are compared with the recent limits
from BAIKAL NT-96, MACRO, and BAKSAN.


title:
Three-Flavor Symmetry of Hadrons Consistent With the Okubo-Zweig-Iizuka
  Rule

abstract:
  It is argued that the only three-flavor symmetry which is consistent with the
Okubo-Zweig-Iizuka (OZI) rule, and is therefore dictated by the gluon gauge
dynamics, is the heavy c quark limit of a certain U(4)_F subgroup (called S_OZI
here) and defined as S_OZI= \lim_(m_c\to \Lambda_c) SU(2)_ud * SU(2)_cd * U(1)
with the two SU(2) groups acting in turn onto the 1st and 2nd quark generations
rather than Gell-Mann's eightfold SU(3)_F. Within this scheme the presence of
non-strange quarkonium components in the wave function of the physical eta and
f_1(1285) mesons appears necessarily through the violation of the OZI rule for
the pseudoscalar and axial vector mesons by the anomalous axial U(1)_A baryon
number current and not by a primordial octet flavor symmetry. The physical
observable which selects the S_OZI over the SU(3)_F scheme is the
non-isotriplet part of the neutral axial current. In the case of the S_OZI
symmetry the only non-isotriplet neutral axial current having a well defined
chiral limit is purely strange, while within the SU(3)_F framework it is the
octet axial current which is supposed to be partially conserved. Accordingly,
while in the latter case the tree level eta N coupling is of significant
strength, its almost vanishes in the former, in agreement with data, thus
confirming the relevance of the S_OZI symmetry.


title: Directional Sensitivity, WIMP Detection, and the Galactic Halo

abstract:
  Distinguishing the signals due to scattering of WIMP dark matter off of
nuclear targets from those due to background noise is a major challenge. The
Earth's motion relative to the galactic halo should produce halo-dependent
seasonal modulation in the event rate, but it also should produce an angular
signal that is both far stronger and less ambiguous. Distinct patterns in the
recoil spectrum can reflect the details of the galactic halo. We derive a new
formalism to calculate angular event rates, and present the predicted angular
signal for a variety of halo models and calculate the number of events needed
to distinguish a dark matter signal from an isotropic background.


title: NLO QCD predictions for internal jet shapes in DIS at HERA

abstract:
  The transverse momentum flow inside jets is a sensitive measure of internal
jet structure. For the current jets in deep inelastic scattering this jet shape
measure is determined at order alpha_s^2, i.e. with up to three partons inside
a single jet. The scale dependence of jet shapes in various jet algorithms is
discussed. Results agree well with recent measurements by the ZEUS
Collaboration, without introducing the hadronization parameter R_sep.


title: Quark liberation and coalescence at CERN SPS

abstract:
  The mischievous linear coalescence approach to hadronization of quark matter
is shown to violate strangeness conservation in strong interactions. The
simplest correct quark counting is shown to coincide with the non-linear
algebraic coalescence rehadronization model, ALCOR. The non-linearity of the
ALCOR model is shown to cancel from its simple predictions for the relative
yields of (multi-)strange baryons. We prove, model independently, that quark
degrees of freedom are liberated before hadron formation in 158 AGeV central Pb
+ Pb collisions at CERN SPS.


title: Introduction to Cosmology

abstract:
  The standard big bang cosmological model and the history of the early
universe according to the grand unified theories of strong, weak and
electromagnetic interactions are summarized. The shortcomings of big bang are
discussed together with their resolution by inflationary cosmology. Inflation
and the subsequent oscillation and decay of the inflaton field are studied. The
density perturbations produced during inflation and their evolution during the
matter dominated era are analyzed. The temperature fluctuations of the cosmic
background radiation are summarized. Finally, the nonsupersymmetric as well as
the supersymmetric hybrid inflationary model is described.


title: Hard Photons and Neutral Pions from RHIC

abstract:
  In order to fix the parameters for predictions of hard photon and pion
production in $Au+Au$ collisions at $\sqrt{s}=200$ GeV, proton-proton and
proton-nucleus data are analyzed in perturbative QCD in the energy range
$\sqrt{s} \approx 20-60$ GeV and a prediction at RHIC energy is given.


title: Effect of Extra Dimensions on Gauge Coupling Unification

abstract:
  The effects of extra dimensions on gauge coupling unification is studied. We
start with a comparison between power law running of the gauge couplings in
models with extra dimensions and logarithmic running that happens in many
realistic cases. We then discuss the effect of extra dimensions on various
classes of unification models. We identify products of evolution coefficients
that dictate the profile of unification in different models. We use them to
study under what conditions unification of couplings can occur in both one and
two step unification models. We find that Kaluza-Klein modes can help generate
interesting intermediate scale models with gauge coupling unification such as
the minimal left-right models with the seesaw mechanism with a $M_{W_R}\sim
10^{13}$ GeV intermediate scale, useful in understanding neutrino oscillations.
We also obtain several examples where the presence of noncanonical
normalization of couplings enables us to obtain unification scales around
$10^{11}$ GeV. This fits very well into a class of models proposed recently
where the string scale is advocated to be at this value from physical
arguments.


title: Infrared safety of impact factors for colourless particle interactions

abstract:
  We demonstrate, to next-to-leading order accuracy, the cancellation of the
infrared singularities in the impact factors which arise in the QCD description
of high energy processes A + B -> A' + B' of colourless particles. We study the
example where A is a virtual photon in detail, but show that the result is true
in general.


title: Pseudoscalar Meson Electroproduction Above the Resonance Region

abstract:
  One principal motivation for studying exclusive reactions is that they
provide a new class of observables, called off-diagonal parton distributions,
for the internal structure of the nucleon. The study of exclusive reactions
provides a probe of nucleon structure complementary to purely inclusive
studies. The simplest, and possibly the most promising, type of experiment is
exclusive electroproduction of pseudoscalar mesons at small t, and at large Q2
and W.
  We show that using the CLAS spectrometer at JLAB and with beam energies
between 4 and 6 GeV, we can obtain good quality electroproduction data that
will improve our understanding of nucleon structure.


title: Soft gluon resummation for heavy quark and dijet cross sections

abstract:
  We discuss the resummation of threshold logarithms for heavy quark and dijet
cross sections in hadronic collisions. The resummed cross sections are
presented at next-to-leading logarithmic accuracy in terms of anomalous
dimension matrices which describe the factorization of soft gluons from the
hard scattering. We apply our formalism to the calculation of the top quark
production cross section at the Fermilab Tevatron.


title: Theoretical Analysis of CPT and Lorentz Tests in Penning Traps

abstract:
  The CPT theorem has been tested to very high precision in a variety of
experiments involving particles and antiparticles confined within Penning
traps. These tests include comparisons of anomalous magnetic moments and
charge-to-mass ratios of electrons and positrons, protons and antiprotons, and
hydrogen ions and antiprotons. We present a theoretical analysis of possible
signals for CPT and Lorentz violation in these systems. We use the framework of
Colladay and Kosteleck\'y, which consists of a general extension of the $SU(3)
\times SU(2) \times U(1)$ standard model including possible CPT and Lorentz
violations arising from spontaneous symmetry breaking at a fundamental level,
such as in string theory. We work in the context of an extension of quantum
electrodynamics to examine CPT and Lorentz tests in Penning traps. Our analysis
permits a detailed study of the effectiveness of experimental tests of CPT and
Lorentz symmetry performed in Penning traps. We describe possible signals that
might appear in principle, and estimate bounds on CPT and Lorentz violation
attainable in present and future experiments.


title:
Power Counting For and Symmetries of the Effective Field Theory For NN
  Interactions

abstract:
  The appropriate power counting for the effective field theory of NN
interactions is reviewed. It is more subtle than in most effective field
theories since in the limit that the S-wave NN scattering lengths go to
infinity it is governed by a nontrivial fixed point. The leading two body terms
in the effective field theory for nucleon self interactions are scale invariant
and invariant under Wigner SU(4) spin-isospin symmetry in this limit. Higher
body terms with no derivatives (i.e., three and four body terms) are
automatically invariant under Wigner symmetry.


title:
Global Lepton-Quark Neutral Current Constraint on Low Scale Gravity
  Model

abstract:
  We perform a global analysis of the lepton-quark neutral current data on the
low scale gravity model, which arises from the extra dimensions. The global
data include HERA neutral current deep-inelastic scattering, Drell-yan
production at the Tevatron, and fermion pair production at LEPII. The Drell-yan
production, due to the large invariant mass data, provides the strongest
constraint. Combining all data, the effective Planck scale must be larger than
about 1.12 TeV for $n=3$ and 0.94 TeV for $n=4$ at 95%CL.


title: Electroproduction of strangeness above the resonance region

abstract:
  A simple and elegant model, based on Reggeized t-channel exchanges is
succesful in reproducing the main features of all existing data of the
reactions ep->eKLambda and ep->eKSigma. In particular, the original way gauge
invariance is taken into account is found to be essential to describe the ratio
between the Coulomb and the Transverse cross-sections at large Q2 that has been
measured recently at JLab.


title: B_c Mesons as a signal of deconfinement

abstract:
  We investigate the fate of bottom quarks produced in heavy-ion collisions at
RHIC. Examining both the direct capture of a charmed quark, and multi-step
processes, where the B_c meson is formed in a sequence of quark capture and
exchange reactions, we find: a) that a sufficiently high number of B_c's will
be produced to generate a detectable tri-lepton signal, and b) that the
production rate of B_c's is highly sensitive to the properties of the
deconfined source. A flavor-independent potential model, which includes color
screening effects, is used to study the propagation of a B_c in a quark-gluon
fireball and to compare this behavior with that of J/Psi mesons.


title:
Proton Decay, Neutrino Oscillations And Other Consequences From
  Supersymmetric SU(6) With Pseudo-Goldstone Higgs

abstract:
  We suggest a new mechanism for naturally suppressing dimension five baryon
number violating in supersymmetric SU(5+N) (N=0, 1,...) GUTs. The mechanism is
realized through suppression of qqT type couplings, and is implemented by
introducing new `matter' multiplets belonging to symmetric representations of
SU(5+N). Together with the suppression of nucleon decay, these multiplets also
enable one to avoid the unwanted asymptotic mass relations $m_s=m_{\mu}$,
$\frac{m_d}{m_s}=\frac{m_e}{m_{\mu}}$.
  As an example, we consider a SU(6) model with pseudo-Goldstone Higgs. By
supplementing the model with an anomalous ${\cal U}(1)$ flavor symmetry, we
also obtain a simple `all-order' solution of the gauge hierarchy problem and
natural explanation of charged fermion mass hierarchies and values of the CKM
matrix elements. The proton life time $\tau_p\sim 10^{2}\tau_p^{SU(5)}$~yr. is
compatible with experiments, with the dominant decay being $p\to K\nu_{\mu,
\tau}$. Thanks to the SU(6) symmetry, successful unification of the gauge
couplings can be retained, and the value of the strong coupling $\alpha_s(M_Z)$
can be reduced to $\simeq 0.12$.
  Finally, we show how to accommodate the solar and atmospheric neutrino data
through the bi-maximal neutrino mixing scenario, with maximal vacuum
$\nu_e-\nu_{\mu, \tau}$ and large angle $\nu_{\mu}-\nu_{\tau}$ oscillations.


title:
$\tau$ polarization asymmetries in $B^+ \to \tau^+\nu_{\tau}\gamma$ and
  $B^+_c \to \tau^+\nu_{\tau}\gamma$

abstract:
  We study the lepton polarization asymmetries in the radiative leptonic B
decays of $B^+\to l^+\nu_{l}\gamma$ and $B^+_{c}\to l^+\nu_{l}\gamma$. We
concentrate on the transverse component of the $\tau$ lepton asymmetries in the
tau decay modes due to CP violation in theories beyond the standard model to
search T violating effect.


title:
Infrared Hierarchy, Thermal Brane Inflation and Superstrings as
  Superheavy Dark Matter

abstract:
  In theories with TeV scale quantum gravity the standard model particles live
on a brane propagating in large extra dimensions. Branes may be stabilized at
large (sub-millimeter) distances from each other, either due to weak Van der
Waals type interactions, or due to an infrared analog of Witten's inverse
hierarchy scenario. In particular, this infrared stabilization may be
responsible for a large size of extra dimensions. In either case, thermal
effects can drive a brief period of the late inflation necessary to avoid the
problems with high reheating temperature and the stable unwanted relics. The
main reason is that the branes which repel each other at zero temperature can
be temporarily glued together by thermal effects. It is crucial that the
temperature needed to stabilize branes on top of each other can be much smaller
than the potential energy of the bound-state, which drives inflation. After
10-15 $e$-foldings bound-states cool below the critical temperature and decay
ending inflation. The parallel brane worlds get separated at this stage and
superstrings (of a sub-millimeter size) get stretched between them. These
strings can have the right density in order to serve as a superheavy dark
matter.


title:
The Monte Carlo Program KORALZ, for the Lepton or Quark Pair Production
  at LEP/SLC Energies -- From version 4.0 to version 4.04

abstract:
  Brief information on new features of KORALZ version 4.04 with respect to
version 4.0 is given. The main difference is that the new version could be used
at LEP2 energies, i.e. up to 240 GeV centre-of-mass system energy. The
possibility to switch on different classes of anomalous couplings is also
included.


title: Faraday effect : a field theoretical point of view

abstract:
  We analyze the structure of the vacuum polarization tensor in the presence of
a background electromagnetic field in a medium. We use various discrete
symmetries and crossing symmetry to constrain the form factors obtained for the
most general case. From these symmetry arguments, we show why the vacuum
polarization tensor has to be even in the background field when there is no
background medium. Taking then the background field to be purely magnetic, we
evaluate the vacuum polarization to linear order in it. The result shows the
phenomenon of Faraday rotation, i.e., the rotation of the plane of polarization
of a plane polarized light passing through this background. We find that the
usual expression for Faraday rotation, which is derived for a non-degenerate
plasma in the non-relativistic approximation, undergoes substantial
modification if the background is degenerate and/or relativistic. We give
explicit expressions for Faraday rotation in completely degenerate and
ultra-relativistic media.


title:
Library of anomalous tau-tau-gamma couplings for tau+ tau- (n gamma)
  Monte Carlo programs

abstract:
  We briefly describe a library that may be used with any e+ e- --> tau+ tau-
(n gamma) Monte Carlo program to account for the effects of anomalous
tau-tau-gamma couplings. The implementation of this library in KORALZ version
4.04 is discussed.


title: Supersymmetry breaking and loop corrections at the end of inflation

abstract:
  We show that quantum corrections to the effective potential in supersymmetric
hybrid inflation can be calculated all the way from the inflationary period -
when the Universe is dominated by a false vacuum energy density - till the
fields settle down to the global supersymmetric minimum of the potential. These
are crucial for getting a continuous description of the evolution of the
fields.


title:
The semileptonic form factors of B and D mesons in the Quark Confinement
  Model

abstract:
  The form factors of the weak currents, which appear in the semileptonic
decays of the heavy pseudoscalar mesons, are calculated within the quark
confinement model by taking into account, for the first time, the structure of
heavy meson vertex and the finite quark mass contribution in the heavy quark
propagators. The results are in quite good agreement with the experimental
data.


title:
Possible scenarios for soft and semi-hard components structure in
  central hadron-hadron collisions in the TeV region: pseudo-rapidity intervals

abstract:
  Continuing previous work on collective variables properties in full phase
space in hadron-hadron collisions in the TeV region our investigation is
extended to multiplicity distributions and clan structure analysis in
pseudo-rapidity intervals. Total multiplicity distributions (MDs) are
considered also here as the weighted superposition of soft and semi-hard
components, and described by Pascal(NB)MD.
  The soft component is characterised by KNO and Feynman scaling behaviour in
all scenarios which differ in the semi-hard component properties only. In fact,
the semi-hard component has been supposed to satisfy, in scenario 1, KNO and
Feynman scaling behaviour and to violate it strongly in scenario 2. A third
possibility has been explored: it is a QCD inspired scenario and leads to
expectations intermediate between the just mentioned two.
  The semi-hard component structure becomes dominant in the TeV energy domain,
a huge mini-jet production is indeed the main phenomenon in this region.
  In addition a new species of clans is generated suggesting a phase transition
in the clan production in scenarios 2 and 3. Our results can be compared with
Tevatron and LHC experimental data when available.


title: $\cN = 1$ supersymmetric constraints for evolution kernels

abstract:
  We provide a complete set of supersymmetric constraints for the anomalous
dimensions of the conformal twist-two operators to all orders of perturbation
theory. Employing them we derive new relations between the exclusive evolution
kernels and apply them in QCD in order to get definite predictions at leading
order and beyond.


title: Axinos as Cold Dark Matter

abstract:
  We show that axinos produced in the early Universe in the decay of the
lightest neutralinos are a natural candidate for cold dark matter. We argue
that axinos may well provide the main component of the missing mass in the
Universe because their relic density is often comparable with the critical
density.


title:
Electric and Weak Electric Dipole Form Factors for Heavy Fermions in a
  General Two Higgs Doublet Model

abstract:
  The electric and weak electric dipole form factors for heavy fermions are
calculated in the context of the most general two-Higgs-doublet model (2HDM).
We find that the large top mass can produce a significant enhancement of the
electric dipole form factor in the case of the b and c quarks. This effect can
be used to distinguish between different 2HDM scenarios.


title: Unitarization of the BFKL Pomeron on a Nucleus

abstract:
  We analyze the evolution equation describing all multiple hard pomeron
exchanges in a hadronic or nuclear structure functions that was proposed
earlier. We construct a perturbation series providing us with an exact solution
to the equation outside of the saturation region. The series demonstrates how
at moderately high energies the corrections to the single BFKL pomeron exchange
contribution which are due to the multiple pomeron exchanges start unitarizing
total deep inelastic scattering cross section. We show that as energy increases
the scattering cross section of the quark-antiquark pair of a fixed transverse
separation on a hadron or nucleus given by the solution of our equation inside
of the saturation region unitarizes and becomes independent of energy. The
corresponding F_2 structure function also unitarizes and becomes linearly
proportional to ln s. We also discuss possible applications of the developed
technique to diffraction.


title:
A Resolution to the Supersymmetric CP Problem with Large Soft Phases via
  D-branes

abstract:
  We examine the soft supersymmetry breaking parameters that result from
various ways of embedding the Standard Model (SM) on D-branes within the Type I
string picture, allowing the gaugino masses and $\mu$ to have large CP-
violating phases. One embedding naturally provides the relations among soft
parameters to satisfy the electron and neutron electric dipole moment
constraints even with large phases, while with other embeddings large phases
are not allowed. The string models provide some motivation for large phases in
the soft breaking parameters. The results generally suggest how low energy data
might teach us about Planck scale physics.


title: Constraining SUSY Models with Spontaneous CP-Violation via B->\psi K_s

abstract:
  We study CP-violating effects in $B\to \psi K_{s}$ decay within minimal
supersymmetric models with spontaneous CP-violation. We find that the
CP-asymmetry predicted by the Standard Model in this decay, $\sin 2\beta \geq
0.4$, cannot be accommodated in these models without violating the bound on the
neutron electric dipole moment. This result holds for NMSSM-like models with an
arbitrary number of sterile superfields. Further implications of the scenario
are discussed.


title:
Calculation of the expansion rate of the three-volume measure in
  high-energy heavy-ion collisions

abstract:
  In ultrarelativistic heavy-ion collisions the local three-volume measure is
expanding in the longitudinal and transverse directions. This is similar to the
Hubble-expansion of the universe, except that the former is not locally
isotropic. As an example the expansion rate is calculated assuming that the
energy-momentum tensor in the central region is that of an ideal fluid,
undergoing Bjorken flow in longitudinal direction, and with initial conditions
as expected for BNL-RHIC energy. While the longitudinal expansion of
three-volume is independent of the energy density of the fluid, in case of 3+1
dimensional expansion the form of the hydrodynamical solution (rarefaction wave
or deflagration shock) affects the three-volume expansion rate on the
hadronization hypersurface. As a consequence the average expansion rate on that
surface depends on the transverse size of the system. This may reflect in an
impact-parameter dependence of the formation probability of light nuclei and of
the freeze-out temperature of the strong interactions in the system.


title: Hard diffraction from small-size color sources

abstract:
  We describe diffractive hard processes in the framework of QCD factorization
and discuss what one can learn from the study of hadronic systems with small
transverse size.


title: Possible Scales of New Physics

abstract:
  The biggest question in beyond the standard model physics is what are the
scales of new physics. Ideas about scales, as well as experimental evidence and
constraints, are surveyed for a variety of possible forms of new physics:
supersymmetry, neutrino masses, unification, and superstring theory.


title: Is Large Mixing Angle MSW the Solution of the Solar Neutrino Problems?

abstract:
  Recent results on solar neutrinos provide hints that the LMA MSW solution
could be correct. We perform accurate calculations for potential `smoking-gun'
effects of the LMA solution in the SuperKamiokande solar neutrino experiment,
including: (1) an almost constant reduction of the standard recoil electron
energy spectrum (with a weak, < 10%, relative increase below 6.5 MeV); (2) an
integrated difference in day-night rates (2% to 14%); (3) an approximately
constant zenith-angle dependence of the nighttime event rate; (4) a new test
for the difference in the shape of the equally-normalized day-night energy
spectra (~ 1%); and (5) annual variations of the signal due to the regeneration
effect (~ 6 times smaller than the integrated day-night effect). We also
establish a relation between the integrated day-night asymmetry and the
seasonal asymmetry due to LMA regeneration. As a cautionary example, we
simulate the effect of an absolute energy calibration error on the shape
(distortion) of the recoil energy spectrum. We compare LMA predictions with
SuperKamiokande data and discuss the possibilities for distinguishing
experimentally between LMA and vacuum oscillations.


title: A Large Mass Hierarchy from a Small Extra Dimension

abstract:
  We propose a new higher-dimensional mechanism for solving the Hierarchy
Problem. The Weak scale is generated from a large scale of order the Planck
scale through an exponential hierarchy. However, this exponential arises not
from gauge interactions but from the background metric (which is a slice of
AdS_5 spacetime). This mechanism relies on the existence of only a single
additional dimension. We demonstrate a simple explicit example of this
mechanism with two three-branes, one of which contains the Standard Model
fields. The experimental consequences of this scenario are new and dramatic.
There are fundamental spin-2 excitations with mass of weak scale order, which
are coupled with weak scale as opposed to gravitational strength to the
standard model particles. The phenomenology of these models is quite distinct
from that of large extra dimension scenarios; none of the current constraints
on theories with very large extra dimensions apply.


title:
Renormalization-Group Effects in the SO(3) Gauge Model With Nearly
  Degenerate Neutrino Masses and Bi-maximal Mixing

abstract:
  The renormalization-group effects on the scenario with nearly degenerate mass
and bi-maximal mixing of neutrinos are analyzed. As a consequence, we
explicitly show in the SO(3) gauge model that the renormalization-group effects
could modify the fitting values of the relevant basic parameters of the model,
but leave the nearly bi-maximal mixing scenario to remain stable for
reconciling both solar and atmospheric neutrino data. The approximately
degenerate Majorana neutrino masses are allowed to be large enough to play a
significant cosmological role without conflicting with the current neutrinoless
double beta decay.


title: D^0 Mixing and Cabibbo Suppressed Decays

abstract:
  The CLEO collaboration reported observation of the `wrong sign' decay $D^0
\to K^+\pi^-$ in 1993. Upgrades have been made to the CLEO detector, including
installation of a silicon vertex detector, which provide substantial
improvements in sensitivity to $D^0 \to K^+\pi^-$. The vertex detector enables
the reconstruction of the proper lifetime of the $D^0$, and so provides
sensitivity to $D^0-\bar{D}^0$ mixing. We will give preliminary results on the
rate of `wrong sign' decay and $D^0-\bar{D}^0$ mixing using data from the $9.1
fb^{-1}$ of integrated luminosity that has been accumulated with the upgrades
in place. In addition, we will give sensitivity estimates of on-shell
$D^0-\bar{D}^0$ mixing derived from measurement of the lifetime measured with
decays of the $D^0$ to CP eigenstates such as $K^+K^-, \pi^+\pi^-$, and
$K_S\phi$.


title:
From Instantons to Sphalerons: Time-Dependent Periodic Solutions of
  SU(2)-Higgs Theory

abstract:
  We solve numerically for periodic, spherically symmetric, classical solutions
of SU(2)-Higgs theory in four-dimensional Euclidean space. In the limit of
short periods the solutions approach tiny instanton-anti-instanton
superpositions while, for longer periods, the solutions merge with the static
sphaleron. A previously predicted bifurcation point, where two branches of
periodic solutions meet, appears for Higgs boson masses larger than $3.091
M_W$.


title:
Library of SM and anomalous WWgamma couplings for the e+e- -> f \bar{f}
  n\gamma Monte Carlo programs

abstract:
  A brief description of the library of the Standard Model and anomalous
WWgamma coupling contribution to the matrix element for e+e- -> \nu \bar{\nu}
n\gamma process is given. It can be used with any Monte Carlo program for e+e-
-> f \bar f n\gamma processes. A working example of the application for the
KORALZ version 4.04 is also provided.


title: Diffraction in Deep Inelastic Scattering

abstract:
  Different theoretical methods used for the description of diffractive
processes in small-x deep inelastic scattering are reviewed. The semiclassical
approach, where a partonic fluctuation of the incoming virtual photon scatters
off a superposition of target colour fields, is used to explain the basic
physical effects. In this approach, diffraction occurs if the emerging partonic
state is in a colour singlet, thus fragmenting independently of the target.
Other approaches, such as the idea of the pomeron structure function and two
gluon exchange calculations, are also discussed in some detail. Particular
attention is paid to the close relation between the semiclassical approach and
the method of diffractive parton distributions, which is linked to the relation
between the target rest frame and the Breit frame point of view. While the main
focus is on diffractive structure functions, basic issues in the diffractive
production of mesons and of other less inclusive final states are also
discussed. Models of the proton colour field, which can be converted into
predictions for diffractive cross sections using the semiclassical approach,
are presented. The concluding overview of recent experimental results is very
brief and mainly serves to illustrate implications of the theoretical methods
presented.


title:
Large Extra Dimension Effects on the Spin Configuration of the Top Quark
  Pair at e^+ e^- Colliders

abstract:
  Large extra dimension effects on the spin configuration of the top quark pair
at the $e^+ e^-\to t\bar{t}$ process are studied. It is shown that the TeV
scale quantum gravity effects cause significant deviations from the Standard
Model predictions for the spin configuration in the off-diagonal basis: they
lead to substantial cross sections of the like-spin states of the top quark
pair, which vanish in the SM; they weaken the pure dominance of the processes,
the Up-Down (Down-Up) spin states for the left-handed (right-handed) beam. In
addition it is shown that the angular cut $-0.5<\cos\theta<0$ is very effective
to determine the sign of the quantum gravity corrections.


title:
Hadronic Total Cross-sections Through Soft Gluon Summation in Impact
  Parameter Space

abstract:
  The Bloch-Nordsieck model for the parton distribution of hadrons in impact
parameter space, constructed using soft gluon summation, is investigated in
detail.
  Its dependence upon the infrared structure of the strong coupling constant
$\alpha_s$ is discussed, both for finite as well as singular, but integrable,
$\alpha_s$. The formalism is applied to the prediction of total proton-proton
and proton-antiproton cross-sections, where screening, due to soft gluon
emission from the initial valence quarks, becomes evident.


title: Phenomenology of atmospheric neutrinos

abstract:
  The relevance of the data concerning upward--going muons for the solution of
the atmospheric neutrino problem is stressed. In particular, their inclusion in
the analysis confirms the goodness of the neutrino oscillation hypothesis and
allows to exclude some alternative, exotic explanations such as neutrino decay,
flavour changing neutral currents, violations of the equivalence principle (at
least in their simplest forms), and also to discriminate, in principle, between
different neutrino oscillation models (nu_mu <-> nu_tau versus nu_mu <-> nu_s),
because of the difference in the matter effects.


title: Urgent problems at small x

abstract:
  Regge theory provides an excellent fit to small-x structure-function data
from Q^2=0 right up to the highest available values, but it also teaches us
that conventional approaches to perturbative evolution are incorrect.


title: Finding the Pion in the Chiral Random Matrix Vacuum

abstract:
  The existence of a Goldstone boson is demonstrated in chiral random matrix
theory. After determining the effective coupling and calculating the scalar and
pseudoscalar propagators, a random phase approximation summation reveals the
massless pion and massive sigma modes expected whenever chiral symmetry is
spontaneously broken.


title: Progress in leptonic and semileptonic decays in lattice QCD

abstract:
  The status of lattice calculations of heavy quark phenomenology is reviewed.
Particular emphasis is placed on the understanding and control of the
calculational uncertainties. The ensuing implications for constraining the CKM
matrix elements are discussed.


title: Extraction of skewed parton distributions from experiment

abstract:
  In this paper we will discuss algorithms for extracting skewed parton
distributions (SPD's) from experiment as well as the relevant process and
experimental observable suitable for the extraction procedure.


title: Multichannel Interaction Analysis of Scalar Mesons Below 1800 MeV

abstract:
  Properties of scalar--isoscalar mesons in a mass range from pi-pi threshold
up to 1800 MeV are analysed using an unitary model with separable interactions
in three decay channels: pi-pi, K-anti K and an effective 2pi-2pi. Different
solutions are obtained by fitting pi-pi and K-anti K data. Analytical structure
of the meson-meson multichannel amplitudes is studied with a special emphasis
on the important role played by the S-matrix zeroes. The dependence of the
positions of S-matrix singularities on the interchannel coupling strength is
investigated. Poles, located in the complex energy plane not too far from the
physical region, are interpreted as scalar resonances: a wide f0(500), a narrow
f0(980) and a relatively narrow f0(1400). In all our solutions two resonances,
lying on different sheets, in the energy region between 1300 MeV and 1500 MeV
are found. These states may be compared with the resonances f0(1370) and
f0(1500) seen in the experiments at CERN. Total, elastic and inelastic channel
cross sections, branching ratios and coupling constants are evaluated and
compared with available data.


title:
Light-Pair Corrections to Small-Angle Bhabha Scattering in a Realistic
  Set-up at LEP

abstract:
  Light-pair corrections to small-angle Bhabha scattering have been computed in
a realistic set-up for luminosity measurements at LEP. The effect of
acollinearity and acoplanarity rejection criteria has been carefully analysed
for typical calorimetric event selections. The magnitude of the correction,
depending on the details of the considered set-up, is comparable with the
present experimental error.


title: Pion Scalar Form Factor and the Sigma Meson

abstract:
  From recent analysis of the $\pi\pi$ scattering amplitude, it has been
claimed that there exists a broad and light $\sigma$ meson. However, if this
meson really exists, it must also appear in other observables such as the pion
scalar form factor. With the use of unitarity and dispersion relations together
with chiral perturbation theory, this form factor is analyzed in the complex
energy plane. The result agrees well with the empirical information in the
elastic region and reveals a resonance pole at $\sqrt{s}=445-i235$ MeV. This
gives further strong evidence for the existence of the $\sigma$ meson.


title: Harmonic Polylogarithms

abstract:
  The harmonic polylogarithms (hpl's) are introduced. They are a generalization
of Nielsen's polylogarithms, satisfying a product algebra (the product of two
hpl's is in turn a combination of hpl's) and forming a set closed under the
transformation of the arguments x=1/z and x=(1-t)/(1+t). The coefficients of
their expansions and their Mellin transforms are harmonic sums.


title: An Investigation of the Hard Contribution to phi Photoproduction

abstract:
  We investigate the possibility that the process of phi photoproduction may
have a significant hard perturbative QCD component. This suggestion is based on
a study of the energy dependence of the forward phi photoproduction cross
section followed by a calculation where we show that a coherent sum of the pQCD
and conventional soft Pomeron contributions provides an excellent reproduction
of the experimental data. Our results suggest that the transition from the
predominantly soft photoproduction of light rho and omega vector mesons to the
predominantly hard photoproduction of heavy J/psi and upsilon is smooth and
gradual, similar to the transition observed in deep inelastic scattering
studies of the proton structure function in the small x limit. Our predictions
for higher HERA energies are presented.


title: From hard thermal loops to Langevin dynamics

abstract:
  In hot non-Abelian gauge theories, processes characterized by the momentum
scale $g^2 T$ (such as electroweak baryon number violation in the very early
universe) are non-perturbative. An effective theory for the soft
($|\vec{p}|\sim g^2 T$) field modes is obtained by integrating out momenta
larger than $g^2 T$. Starting from the hard thermal loop effective theory,
which is the result of integrating out the scale $T$, it is shown how to
integrate out the scale $gT$ in an expansion in the gauge coupling $g$. At
leading order in $g$, one obtains Vlasov-Boltzmann equations for the soft field
modes, which contain a Gaussian noise and a collision term. The 2-point
function of the noise and the collision term are explicitly calculated in a
leading logarithmic approximation. In this approximation the Boltzmann equation
is solved. The resulting effective theory for the soft field modes is described
by a Langevin equation. It determines the parametric form of the hot baryon
number violation rate as $\Gamma = \kappa g^{10} \log(1/g) T^4$, and it allows
for a calculation of $\kappa$ on the lattice.


title:
Three-family oscillations using neutrinos from muon beams at very long
  baseline

abstract:
  The planned LBL experiments will be able to prove the hypothesis of flavor
oscillation between muon and tau neutrinos. We explore the possibility of a
second generation long baseline experiment at very long baseline, i.e. L in the
range 5000-7000 km. This distance requires intense neutrino beams that could be
available from very intense muon beams as those needed for $\mu$ colliders.
Such baselines allow the study of neutrino oscillations with $E/L \approx
2\times 10^{-3} eV^2$ with neutrinos of energy $E_\nu \approx 10 GeV$, i.e.
above tau threshold. Moreover, matter effects inside the Earth could lead to
observable effects in $\nu_e \to \nu_\mu$ oscillations. These effects are
interchanged between neutrinos and antineutrinos, and therefore they can be
tested by comparing the oscillated spectra obtained running the storage ring
with positive and negative muons.


title: Riddle of the scalars: where is the sigma?

abstract:
  The riddle of the sigma is recast in a way that tries to differentiate fact
from fiction as a basis for future/further discussion. By doing this, it is
hoped that the role of the sigma as dominating the ubiquitous $\pi\pi$
interactions below 1 GeV and its relation to the QCD vacuum can be clarified.


title: Production of Massive Fermions at Preheating and Leptogenesis

abstract:
  We present a complete computation of the inflaton decay into very massive
fermions during preheating. We show that heavy fermions are produced very
efficiently up to masses of order 10^{17}-10^{18} GeV; the accessible mass
range is thus even broader than the one for heavy bosons. We apply our findings
to the leptogenesis scenario, proposing a new version of it, in which the
massive right-handed neutrinos, responsible for the generation of the baryon
asymmetry, are produced during preheating. We also discuss other production
mechanisms of right-handed neutrinos in the early Universe, identifying the
neutrino mass parameters for which the observed baryon asymmetry is reproduced.


title: Periodic Instantons in SU(2) Yang-Mills-Higgs Theory

abstract:
  The properties of periodic instanton solutions of the classical SU(2) gauge
theory with a Higgs doublet field are described analytically at low energies,
and found numerically for all energies up to and beyond the sphaleron energy.
Interesting new classes of bifurcating complex periodic instanton solutions to
the Yang-Mills-Higgs equations are described.


title: D--term Inflation at the TeV Scale and Large Internal Dimensions

abstract:
  We show that D--term inflation at the TeV scale is possible in the presence
of large internal dimensions. This requires very small couplings and masses
which arise from the large size of the compact dimensions. We show that
acceptable number of e-folds, magnitude and spectrum of density perturbations
$\delta \rho/\rho$ and $\eta$ can be obtained in this scenario at the price of
a reheating temperature which is too high. Demanding an acceptable $T_R$
results in very small density perturbations.


title:
Chemical equilibration and thermal dilepton production from the quark
  gluon plasma at finite baryon density

abstract:
  The chemical equilibration of a highly unsaturated quark-gluon plasma has
been studied at finite baryon density. It is found that in the presence of
small amount of baryon density, the chemical equilibration for gluon becomes
slower and the temperature decreases less steeply as compared to the baryon
free plasma. As a result, the space time integrated yield of dilepton is
enhanced if the initial temperature of the plasma is held fixed. Even at a
fixed initial energy density, the suppression of the dilepton yields at higher
baryo-chemical potential is compensated, to a large extent, by the slow cooling
of the plasma.


title: Sterile neutrinos?

abstract:
  The notion of sterile neutrinos is discussed. The schemes of mixing of four
massive neutrinos, which imply the existence of sterile neutrinos, are briefly
considered. Several model independent methods that allow to reveal possible
transitions of solar neutrinos into sterile states are presented.


title:
The parton to hadron phase transition observed in Pb+Pb collisions at
  158 GeV per nucleon

abstract:
  Hadronic yields and yield ratios observed in Pb+Pb collisions at the SPS
energy of 158 GeV per nucleon are known to resemble a thermal equilibrium
population at T=180 +/- 10 MeV, also observed in elementary e+ + e- to hadron
data at LEP. We argue that this is the universal consequence of the QCD parton
to hadron phase transition populating the maximum entropy state. This state is
shown to survive the hadronic rescattering and expansion phase, freezing in
right after hadronization due to the very rapid longitudinal and transverse
expansion that is inferred from Bose-Einstein pion correlation analysis of
central Pb+Pb collisions.


title: Extensive air showers rounded up by aires + sibyll/qgsjet

abstract:
  An analysis of the differences introduced by the hadronic interaction event
generators during the development of the showers is presented. We have
generated proton and nuclei induced air showers with energies up to $10^{20.5}$
eV, ``herded up'' by the code aires + sibyll/ qgsjet. The most relevant
observables are taken into account for the comparison.


title: Two-loop self-energy master integrals on shell

abstract:
  Analytic results for the complete set of two-loop self-energy master
integrals on shell with one mass are calculated.


title: The J^PC = 0^++ scalar meson nonet and glueball of lowest mass

abstract:
  The evidence for the low mass J^{PC}=0^{++} states is reconsidered. We
suggest classifying the isoscalars f_0(980) and f_0(1500) as members of the
0^{++} nonet, with a mixing rather similar to that of the pseudoscalars \eta'
and \eta. The broad state called f_0(400-1200) or `sigma'' and the state
f_0(1370) are considered as different signals from a single broad resonance,
which we take to be the lowest-lying 0^{++} glueball. The main arguments in
favor of these hypotheses are presented and compared with theoretical
expectations.


title:
Schwinger-Dyson approach and generalized impulse approximation for the
  pi0 gamma^* gamma transition

abstract:
  We review the pion-photon transition form factor calculated in the
Schwinger-Dyson approach and an impulse approximation. We present results for
it far above the scales presently accessible for measurement, up to 36 GeV^2,
and demonstrate agreement with the analytically inferred asymptotic behavior,
for which we also provide a new derivation. We discuss how measurements at
Jefferson Lab can provide information on how quarks are dynamically dressed.


title: A low-energy solution to the mu-problem in gauge mediation

abstract:
  In the gauge-mediation framework the soft supersymmetry breaking mass
parameters of the supersymmetric standard model are induced by the gauge
interactions of some messenger fields. The parameters exhibit flavor
universality which is dictated by the gauge interactions and which efficiently
eliminates new dangerous contributions to flavor changing neutral currents.
However, the Higgs potential in this framework typically contains an
unacceptable hierarchy between its dimensionful parameters (the $\mu$-problem
of gauge mediation). We show that the problem can be resolved if the Higgs
potential arises dynamically once an intermediate U(1)' sector is integrated
out rather than arising radiatively from some Yukawa interactions at the
messenger scale. As an added benefit, such models may naturally avoid new
contribution to CP violating amplitudes. The proposed framework is described,
explicit examples are given and its phenomenology is explored. The $\mu$
problem is resolved in this case by the low-energy U(1)' dynamics which could
be tested in future collider experiments.


title:
Magnetic Oscillations in Dense Cold Quark Matter with Four-Fermion
  Interactions

abstract:
  The phase structures of Nambu-Jona-Lasinio models with one or two flavours
have been investigated at non-zero values of $\mu$ and $H$, where $H$ is an
external magnetic field and $\mu$ is the chemical potential. In the phase
portraits of both models there arise infinitely many massless chirally
symmetric phases, as well as massive ones with spontaneously broken chiral
invariance, reflecting the existence of infinitely many Landau levels. Phase
transitions of first and second orders and a lot of tricritical points have
been shown to exist in phase diagrams. In the massless case, such a phase
structure leads unavoidably to the standard van Alphen-de Haas magnetic
oscillations of some thermodynamical quantities, including magnetization,
pressure and particle density. In the massive case we have found an oscillating
behaviour not only for thermodynamical quantities, but also for a dynamical
quantity as the quark mass. Besides, in this case we have non-standard, i.e.
non-periodic, magnetic oscillations, since the frequency of oscillations is an
$H$-dependent quantity.


title: New developments in neutrino physics

abstract:
  A review of the problem of neutrino mass, mixing and oscillations is given.
Possible phenomenological schemes of neutrino mixing are discussed. The most
important consequences of neutrino mixing--neutrino oscillations are considered
in some details. The data of atmospheric, solar and LSND experiments are
discussed. The results of phenomenological analyses of the data under the
assumption of the mixing of three and four massive neutrinos are shortly
presented.


title:
A nonextensive thermodynamical equilibrium approach in $e^+ e^- \to
  hadrons$

abstract:
  We show that the inclusion of long distance effect, expected in strong
interactions, through a nonextensive thermodynamical approach is able to
explain the experimental distribution of the transverse momentum of the hadrons
with respect to the jet axis ($p_{t}$) $e^+ e^- \to hadron$ reaction. The
observed deviation from the exponential behavior, predicted by the
Boltzmann-Gibbs thermodynamical treatment, is automatically recovered by the
nonextensive Tsallis statistics used here. We fitted the observed $p_{t}$
spectrum in the range of 14 GeV to 161 GeV and obtained, besides a good fit,
the theoretical important fact that the temperature becomes independent of the
primary energy.


title: Inflationary Reheating and Fermions

abstract:
  Coherent oscillations of the inflaton field at the end of inflation can
parametrically excite fermions in much the same way that bosons are created in
preheating. Although Pauli-blocking prohibits the occupation number of created
fermions from growing exponentially, fermion production occurs in a manner
significantly different from the expectations of simple perturbation theory.
Here, I discuss the nature of fermion production after inflation and possible
applications including the efficient transfer of inflaton energy and the
production of super-massive fermions during fermionic preheating.


title: Neutrino Physics

abstract:
  The basic concepts of neutrino physics are presented at a level appropriate
for integration into elementary courses on quantum mechanics and/or modern
physics.


title:
Covariant Classification of q q bar-Meson Systems and Existence of New
  Scalar and Axial-Vector Mesons

abstract:
  The level classification of quark-antiquark systems is generally made by the
LS-coupling scheme, resorting to the non-relativistic quark model. However, it
has been well known that the pi-meson with the (L,S)=(0,0) shows also the
properties as a Nambu-Goldstone boson in the case of spontaneous breaking of a
relativistic symmetry, the chiral symmetry. In this talk I present a covariant
classification scheme for describing both the non-relativistic and the
relativistic q q bar-mesons and point out possibility for existence of the new
scalar meson nonet (to be assigned to the sigma nonet) and also of the new
axial-vector meson nonet, ``chiralons,'' which should be discriminated from the
conventional ^3P_0 and ^3P_1 states, respectively.


title:
Existence of sigma(600)/kappa(900) and Possible Classification of Chiral
  Scalar Nonet

abstract:
  Recently, by reanalyzing the phase shift data of I=0 pipi$ and of I=1/2 Kpi
scatterings, we showed the evidences for existence of light scalar mesons,
sigma(600) and kappa(900), respectively, which had been sought but missing for
a long time. The sigma(600) and kappa(900) together with the established
resonances, a_0(980) and f_0(980), are shown to be consistently classified as
the members of a single scalar sigma-nonet, appearing in the SU(3) linear sigma
model. Especially the mass value of the iso-singlet flavor-octet member
satisfies, together with those of kappa(900) and a_0(980), the Gell-Mann Okubo
mass formula. The repulsive background phase shift delta_{BG}, which was
essential to lead the sigma/kappa-existence in our phase shift analyses, is
also shown to be quantitatively describable in the framework of linear sigma
model. Thus, the origin of delta_{BG} is reduced to the ``compensating lambda
phi^4-interaction," necessary from the viewpoint of chiral symmetry.


title:
Controversies on and a Reasoning for Existence of the light
  sigma-particle

abstract:
  The light sigma-particle is, regardless of the strong criticism, reviving
recently due to the works done from various sides. I review essential points of
the controversies (especially related to our works) and of their answer:
Conventionally a large concentration of the iso-scalar S-wave 2 pi events below
1 GeV (being, correctly, due to the sigma-production), which is observed in
most of production processes, is interpreted as a mere background from the
viewpoint of, so called, universality argument. However, I show, by resorting
to a simple field theoretical model, that the argument is not correct and the
production process has ``its own value'' independent of the scattering process.
Thus it is suggested that the present index ``f_0(400-1200) or sigma'' in
PDG'98 is to be changed as ``sigma(400-800)'' in the PDG 2000.


title: Observed Properties of sigma-particle

abstract:
  Recently we obtained the evidence for the existence of sigma(600) meson,
which had been sought but missing for a long time, by reanalyzing the I=0
S-wave pi pi scattering phase shift. The sigma-existence was also suggested
through the analyses of pi pi production processes, pp central collision pp to
pp pi^0 pi^0 and J/psi to omega pi pi decay. The observed properties through
these works of sigma meson satisfy the mass and width relation of SU(2) linear
sigma model. The physical origin of the repulsive background phase shift
delta_{BG}, which was essential to lead to the sigma-existence in our phase
shift analysis, is also due to the "compensating lambda phi^4-interaction" in
linear sigma model. Furthermore in this talk the experimental property of the
delta_{BG} is shown to be describable quantitatively in the framework of linear
sigma model including rho-meson contribution.


title:
Significance of the Sigma Meson in Hadron Physics (QCD) and Possible
  Experiments to Observe it

abstract:
  We first discuss the theoretical and phenomenological significance of the
sigma meson ($\sigma$) in QCD. It is indicated that if the collective modes
with the mass 500-600 MeV exists in the $I=J=0$ channel, various empirical
facts in hadron physics can be naturally accounted for, which otherwise would
remain mysterious. We propose several experiments to produce and detect the
$\sigma$ in nuclei using nuclear and electro-magnetic projectiles. The recent
CHAOS data which show a spectral enhancement near the 2 $m_{\pi}$ threshold in
the $\sigma$ channel from the reactions A$(\pi, 2\pi)$A' where A and A' denotes
nuclei is interpreted as a possible evidence of a partial restoration of chiral
symmetry in nuclei.


title:
Scaling violations and off-forward parton distributions: leading order
  and beyond

abstract:
  We give an outline of a formalism for the solution of the evolution equations
for off-forward parton distributions in leading and next-to-leading orders
based on partial conformal wave expansion and orthogonal polynomials
reconstruction.


title:
Strange-quark mass from combined e+e- and tau-decay data:test of the
  isospin symmetry and implications on epsilon'/\epsilon and m_{u,d}

abstract:
  I extract the strange-quark mass using a $\tau$-like decay sum rule for the
$\phi$-meson, and some other sum rules involving its difference with the vector
component of the hadronic $\tau$-decay. As a conservative estimate, one obtains
to order $\alpha_s^3$: $\bar{m}_s$(1 GeV) = $(178\pm 33)$ MeV $\lrar
\~\bar{m}_s$(2 GeV) = $(129\pm 24)$ MeV, while the positivity of the spectral
function leads to the upper bound: $\bar{m}_s(1 {\rm GeV})\leq (200\pm 28)
{MeV} \Longrightarrow~\bar{m}_s(2~{\rm GeV})\leq (145\pm 20) {MeV}$. These
results are in good agreement with the existing sum rule and $\tau$-decay
results, and, in particular, with the result from the the sum rule involving
the difference of the isoscalar and isovector components of the $e^+e^-\rar$
hadrons data. This signals small effects of the SU(2) isospin violation due to
the $\omega$-$\rho$ mixing parameters, and questions the reliability of the
existing sum rule estimates of these parameters. Combining our result with the
recent data on $\epsilon'/\epsilon$, we can estimate, within the standard
model, the four-quark weak matrix elements $B_6^{1/2}-0.54 B^{3/2}_8$ to be
about $ (2.8\pm 1.3)$. This result may suggest a large violation of the vacuum
saturation estimate similarly to the case of the four-quark condensates
obtained from the sum rules analysis, and can serve as a guide for a future
accurate non-perturbative extraction of such matrix elements. Combining our
result with the sum rule estimate of $m_u+m_d$ and with the Dashen formula for
the mass ratio, one can deduce the update values: $\bar{m}_d(2 {\rm GeV})=
(6.4\pm 1.1) {\rm MeV}$ and $\bar{m}_u(2 {\rm GeV})= (2.3\pm 0.4) {\rm MeV}$.


title:
Incompatibility of simultaneous non-linear realizations of scale
  symmetry and supersymmetry

abstract:
  Simultaneous nonlinear realizations of supersymmetry and softly broken scale
and chiral symmetries are investigated. To guarantee Nambu-Goldstone
realizations of the symmetries, the Goldstino decay constant is forced to vary
as the explicit soft scale and chiral symmetry breaking parameters.
Consequently, it must vanish in the chiral limit and the simultaneous nonlinear
realizations of the super and scale symmetries proves inconsistent.


title: Supersymmetric Higgs Pair Production at Hadron Colliders

abstract:
  We study the pair production of neutral Higgs bosons through gluon fusion at
hadron colliders in the framework of the Minimal Supersymmetric Standard Model.
We present analytical expressions for the relevant amplitudes, including both
quark and squark loop contributions, and allowing for mixing between the
superpartners of left- and right-handed quarks. Squark loop contributions can
increase the cross section for the production of two CP-even Higgs bosons by
more than two orders of magnitude, if the relevant trilinear soft breaking
parameter is large and the mass of the lighter squark eigenstate is not too far
above its current lower bound. In the region of large $\tan \beta$, neutral
Higgs boson pair production might even be observable in the $4 b$ final state
during the next run of the Tevatron collider.


title: New Physics in CP Violating B Decays

abstract:
  We discuss the sensitivity of the CP violating measurements at the upcoming B
factories to the presence of physics beyond the Standard Model. We review the
three manifestations of CP violation possible in the B meson system. We give
examples of decay modes for each of these which are sensitive to new physics,
are experimentally feasible, and theoretically clean. Finally, we present
techniques to extract Standard Model parameters in the presence of new physics.


title:
Renormalization Group Analysis of \rho-Meson Properties at Finite
  Density

abstract:
  We calculate the density dependence of the $\rho$-meson mass and coupling
constant($g_{\rho NN}$) for $\rho$-nucleon-nucleon vertex at one loop using the
lagrangian where the $\rho$-meson is included as a dynamical gauge boson of a
hidden local symmetry. From the condition that thermodynamic potential should
not depend on the arbitrary energy scale, renormalization scale, one can
construct a renormalization group equation for the thermodynamic potential and
argue that the various renormalization group coefficients are functions of the
density or temperature. We calculate the $\beta$-function for
$\rho$-nucleon-nucleon coupling constant ($g_{\rho NN}$) and $\gamma$-function
for $\rho$-meson mass ($\gamma_{m_\rho}$). We found that the $\rho$-meson mass
and the coupling constant for $g_{\rho NN}$ drop as density increases in the
low energy limit.


title: Coupled gap equations for the screening masses in the SU(2) Higgs model

abstract:
  The complete set of static screening masses is determined for the SU(2) Higgs
model from one-loop coupled gap equations. Results from the version, containing
scalar fields both in the fundamental and adjoint representations are compared
with the model arising when the integration over the adjoint scalar field is
performed. A non-perturbative and non-linear mapping between the couplings of
the two models is proposed, which exhibits perfect decoupling of the heavy
adjoint scalar field. Also the alternative of a gauge invariant mass
resummation is investigated in the high temperature phase.


title:
Event-by-event cluster analysis of final states from heavy ion
  collisions

abstract:
  We present an event-by-event analysis of the cluster structure of final
multihadron states resulting from heavy ion collisions. A comparison of
experimental data with the states obtained from Monte Carlo generators is
shown. The analysis of the first available experimental events suggests that
the method is suitable for selecting some different types of events.


title: Top-quark physics in six-quark final states at the Next Linear Collider

abstract:
  The processes of six-quark production with one $b\bar b$ pair are studied by
means of a complete tree-level electroweak calculation. The top-quark signal is
examined: the importance of electroweak backgrounds, of the order of 10% above
the $t\bar t$ threshold and of about 30% of the purely electroweak signal at
threshold, is further stressed by studying the dependence of the cross-section
at threshold on the Higgs mass in the range between 100 GeV and 185 GeV, and
finding variations of the order of 10%. In the study of some event-shape
variables, a strong effect of initial-state radiation is found, in particular
for the thrust distribution, which is studied for several centre-of-mass
energies at the TeV scale. The effectiveness of cuts on the thrust for
isolating QCD backgrounds, as pointed out by some authors, is confirmed also in
the presence of electroweak backgrounds and initial-state radiation.


title: On magnetic catalysis in even-flavor QED3

abstract:
  In this paper, we discuss the role of an external magnetic field on the
dynamically generated fermion mass in even-flavor QED in three space-time
dimensions. Based on some reasonable approximations, we present analytic
arguments on the fact that, for weak fields, the magnetically-induced mass
increases quadratically with increasing field, while at strong fields one
crosses over to a mass scaling logarithmically with the external field. We also
confirm this type of scaling behavior through quenched lattice calculations
using the non-compact version for the gauge field. Both the zero and finite
temperature cases are examined. A preliminary study of the fermion condensate
in the presence of magnetic flux tubes on the lattice is also included.


title: Weak dipole moments in $\tau$ decays to hadrons

abstract:
  A description of three body tau decays with general vectorial and derivative
(non-minimal) couplings is presented for experiments where the tau direction of
flight is not reconstructed. The proposed interactions may be due to charged
current weak dipole moment couplings and hence to structure of the $\tau$
lepton. The decay distribution is expressed in terms of seven real parameters
plus an overall normalization factor. Comments on the extension of the
formalism to two-body decays are included. The particular cases of $\TA1$ and
$\TP2$ are discussed in detail.


title: Chiral Disorder and Diffusion in The QCD Vacuum

abstract:
  In this talk, which popularizes some of our recent work, we provide novel
insights into the bulk properties of light chiral quarks in a fixed Euclidean
volume (e.g. lattice QCD). We show that the spontaneous breakdown of chiral
symmetry results into diffusing quarks with a vacuum diffusion constant
$D=2F_{\pi}^2/|<\bar{q}q>|$ $\approx 0.22$ fm, in striking analogy to diffusing
electrons in disordered metals in one-, two- and three-dimensions.

categories: hep-ph chao-dyn cond-mat hep-lat nlin.CD nucl-th


title: A Hexagonal Theory of Flavor

abstract:
  We construct a supersymmetric theory of flavor based on the discrete gauge
group (D_6)^2, where D_6 describes the symmetry of a regular hexagon under
proper rotations in three dimensions. The representation structure of the group
allows one to distinguish the third from the lighter two generations of matter
fields, so that in the symmetry limit only the top quark Yukawa coupling is
allowed and scalar superpartners of the first two generations are degenerate.
Light fermion Yukawa couplings arise from a sequential breaking of the flavor
symmetry, and supersymmetric flavor-changing processes remain adequately
suppressed. We contrast our model with others based on non-Abelian discrete
gauge symmetries described in the literature, and discuss the challenges in
constructing more minimal flavor models based on this approach.


title:
Quark-mass effects for jet production in e^+ e^- collisions at the
  next-to-leading order: results and applications

abstract:
  We present a detailed description of our calculation of next-to-leading order
QCD corrections to heavy quark production in e^+ e^- collisions including mass
effects. In particular, we study the observables $R_3^{b\ql}$ and $D_2^{b\ql}$
in the E, EM, JADE and DURHAM jet-clustering algorithms and show how one can
use these observables to obtain $m_b(m_Z)$ from data at the $Z$ peak.


title: B -> K^* gamma from D -> K^* l nu

abstract:
  The B -> K^* gamma branching fraction is predicted using heavy quark spin
symmetry at large recoil to relate the tensor and (axial-)vector form factors,
using heavy quark flavor symmetry to relate the B decay form factors to the
measured D -> K^* l nu form form factors, and extrapolating the semileptonic B
decay form factors to large recoil assuming nearest pole dominance. This
prediction agrees with data surprisingly well, and we comment on its
implications for the extraction of |Vub| from B -> rho l nu.


title:
An efficient renormalization group improved implementation of the MSSM
  effective potential

abstract:
  In the context of MSSM, a novel improving procedure based on the
renormalization group equation is applied to the effective potential in the
Higgs sector. We focus on the one-loop radiative corrections computed in Landau
gauge by using the mass independent renormalization scheme $\bar{DR}$. Thanks
to the decoupling theorem, the well-known multimass scale problem is
circumvented by switching to a new effective field theory every time a new
particle threshold is encountered. We find that, for any field configuration,
there is a convenient renormalization scale $\tilde{Q}^*$ at which the loop
expansion respects the perturbation series hierarchy and the theory retains the
vital property of stability.


title:
A contribution to the discussion of the matter-antimatter asymmetry
  problem

abstract:
  Using a more accurate effective Hamiltonian governing the time evolution in
the particle-antiparticle subspace of states than the one obtained within the
Lee-Oehme--Yang approach we show that in the case of particles created at the
initial instant t = 0 only the masses of a stable particle and its antiparticle
are the same at all t > 0 in a CPT invariant system, whereas the masses of an
unstable particle and its antiparticle are equal only at t = 0 and then during
their time evolution they become slightly different for times t >> 0 if CP
symmetry is violated but CPT symmetry holds. This property is used to show that
if the baryon number B is not conserved then the asymmetry between numbers of
unstable baryons and antibaryons can arise in a CPT invariant system at t >> 0
even in the thermal equilibrium state of this system.


title:
Representation of the virtual Compton amplitude for polarized scattering
  in the generalized Bjorken region

abstract:
  The Compton amplitude is calculated in terms of expectation values of
light-ray quark operators. As a technical tool we apply the nonlocal light-cone
expansion. Thereby we express the expectation value of the vector light-ray
operator with the help of the expectation value of the corresponding scalar
operator of twist 2. This allows important simplifications. In the limit of
forward scattering the integral relations between the twist-2 contributions of
the structure functions are implied directly.


title: What is the limit on the Higgs mass?

abstract:
  We obtain the bounds on all the gauge invariant, flavour symmetric, CP-even
operators of dimension 6 that can affect the electroweak precision tests. For
the preferred Higgs mass of about 100 GeV, their minimal scales range from 2 to
10 TeV. Depending on the individual operator, these limits are often
significantly stronger than those quoted in the literature, when they exist at
all. The impact, if any, of these bounds on the upper limit con the Higgs mass
itself is discussed.


title: Comparing the Broken U3xU3 Linear Sigma Model with Experiment. U3xU3

abstract:
  The linear sigma model with broken U3xU3 is compared with data on the
lightest scalar and pseudoscalar mesons. When 5 of the 6 parameters are fixed
by the pseudoscalar masses and decay constants one finds that, already at the
tree level, a reasonable description for the 4 scalar masses, mixing and up to
8 tri-linear couplings of lightest scalars, taken as a0(980), f0(980),
sigma(500) and K*0(1430). This clearly indicates that these scalars are the
chiral partners of the pi, eta, eta', K and strongly suggests that they like
the latter are (unitarized) quark-antiquark states.


title:
Two photons plus jet al LHC: the NNLO contribution from the gg initiated
  process

abstract:
  The production of the Standard Model Higgs boson of mass ~ 100-140 GeV at the
LHC likely gives clear signals in the $\gamma \gamma$ (1) and in the $\gamma
\gamma jet$ (2) channels. The quantitative evaluation of the background to
channel (1) is very hard since the next-to-leading order (NLO) and
next-to-next-to-leading order (NNLO) QCD corrections are large. In particular,
the contributions of the NNLO QCD subprocess $gg -> \gamma \gamma$ to inclusive
$\gamma\gamma$ production is comparable to the contribution of the leading
order subprocess $q\bar{q} -> \gamma \gamma$. The quantitative description of
the background to channel (1), therefore, requires to calculate all corrections
up to the NNNLO level. In this letter we present results on the contribution of
the NNLO QCD subprocess $gg -> g \gamma \gamma$ to the production rate of
channel (2). We have found that in this case this NNLO contribution is less
than 20% of the Born contribution. Since the NNLO contributions will likely be
dominated by this subprocess one can argue that in the case of channel (2) -
contrary to the case of channel (1)- a quantitative description of the
background can be achieved already at next-to-leading order accuracy.


title: The "radiative Delta -> N gamma" decay in light cone QCD

abstract:
  The "g_{Delta N gamma}" coupling for the "Delta -> N gamma" decay is
calculated in framework of the light cone QCD sum rules and is found to be
g_{Delta N gamma} = (1.6 pm 0.2) GeV^(-1). Using this value of g_{Delta N
gamma} we estimate the branching ratio of the Delta^+ -> N gamma decay, which
is in a very good agreement with the experimental result.


title: Orsay Lectures on Confinement (III)

abstract:
  This is the third lecture on quark confinement given by V.N.Gribov in 1992 in
Orsay. An extensive discussion of the consequences of all this for the
structure of the Green function can be found in [5,6] - in the two last papers
concluding his 20 years long study of the problem of quark confinement in QCD.
  The text was prepared for publication by Yu. Dokshitzer, B. Metsch and J.
Nyiri on the basis of a tape recording and notes taken during the lecture.


title:
Path-Integral Formulation of Casimir Effects in Supersymmetric Quantum
  Electrodynamics

abstract:
  The Casimir effect is an interesting phenomenon in the sense that it provides
us with one of the primitive means of extracting the energy out of the vacuum.
Since the original work of Casimir a number of works have appeared in extending
the result to the case of more general topological and dynamical configurations
of the boundary condition and to the circumstances at finite temperature and
gravity. In the studies of the Casimir effects it is common to assume the free
electromagnetic field in the bounded region. It may be interesting to extend
our arguments for fields other than the electromagnetic field. The Casimir
effect due to the free fermionic fields has been investigated by several
authors and has been found to result in an attractive force under the suitable
physical boundary conditions.


title:
Comments on Exclusive Electroproduction of Transversely Polarized Vector
  Mesons

abstract:
  We discuss the electroproduction of light vector mesons from transversely
polarized photons. Here QCD factorization cannot be applied as shown explicitly
in a leading order calculation of corresponding Feynman diagrams. It is
emphasized that present infrared singular contributions cannot be regularized
through phenomenological meson distribution amplitudes with suppressed endpoint
configurations. We point out that infrared divergencies arise also from
integrals over skewed parton distributions of the nucleons.
  In a phenomenological analysis of transverse vector meson production model
dependent regularizations have to be applied. If this procedure preserves the
analytic structure suggested by a leading order calculation of Feynman
diagrams, one obtains contributions from nucleon parton distributions and their
derivatives. In particular polarized gluons enter only through their
derivative.


title: Diffractive photoproduction of Upsilon states at HERA

abstract:
  Cross sections for the diffractive photoproduction of the Upsilon-family at
HERA energies, within the framework of the analysis by Frankfurt, Koepf and
Strikman, are presented. They compare well with the recent preliminary data
from ZEUS and H1. Two novel effects lead to a significant enhancement of the
original calculation: the non-diagonal (or skewed) kinematics, calculated to
leading-log(Q^2) accuracy, and the large magnitude of the real part of the
amplitude. A considerably stronger rise in energy is predicted than that found
in J/Psi-production.


title:
Collision integral for multigluon production in a scalar quark and gluon
  model

abstract:
  A model of scalar gluons and scalar quarks that successfully gives a ln s
behavior in high energy qq scattering and which contains a three gluon vertex
is used to derive transport equations for the quarks and gluons. Quasiparticle
and semiclassical approximations are utilized. In particular, the collision
integral is studied. At first the terms are organized according to the number
of gluon exchange interactions, and it is shown explicitly that the occurrence
of all two body differential scattering cross sections in the Boltzmann
equation requires an evaluation of all terms to this order. One obtains qg->
qg, q bar q->gg, qq->qq, and q bar q -> q bar q. An additional ordering
according to the inverse number of colors reveals that the quark loop diagrams
are suppressed, and diagrams that lead to gluon production or scattering
dominate. The self energy with three gluons exchanged is then examined. From
this, it is evident that initial as well as final state interactions enter into
a generalized collision integral. The generalized Boltzmann-like equation
involving n gluon exchange for quark transport is given.


title: Yukawa Structure with Maximal Predictability

abstract:
  A simple Ansatz for the quark mass matrices is considered, based on the
assumption of a power structure for the matrix elements and the requirement of
maximal predictability. A good fit to the present experimental data is obtained
and the position of the vertex of the unitarity triangle, i.e.
(\bar{\rho},\bar{\eta}), is predicted.


title: Pade-Summation Approach to QCD Beta-Function Infrared Properties

abstract:
  We address whether Pad\'e-summations of the $\bar{MS}$ QCD $\beta$-function
for a given number of flavours exhibit an infrared-stable fixed point, or
alternatively, an infrared attractor of a double valued couplant as noted by
Kogan and Shifman for the case of supersymmetric gluodynamics. Below an
approximant-dependent flavour threshold $(6 \leq n_f \leq 8)$, we find that
Pad\'e-summation $\beta$-functions incorporating $[2|1], [1|2], [2|2], [1|3]$,
and $[3|1]$ approximants always exhibit a positive pole prior to the occurrence
of their first positive zero, precluding any identification of this first
positive zero as an infrared-stable fixed point of the $\beta$- function. This
result is shown to be true regardless of the magnitude of the presently-unknown
five-loop $\beta$-function contribution. Moreover, the pole in question
suggests the occurrence of dynamics in which both a strong and an
asymptotically-free phase share a common infrared attractor. We briefly discuss
the possible relevance of infrared-attractor dynamics to the success of recent
calculations of the glueball mass spectra in QCD with $N_c \to \infty$ via
supergravity. As $n_f$ increases above an approximant-dependent flavour
threshold, Pad\'e-summation $\beta$-functions incorporating $[2|2], [1|3]$, and
$[3|1]$ approximants exhibit dynamics controlled by an infrared-stable fixed
point over a widening domain of the five-loop $\bar{MS}$ $\beta$-function
parameter $(\beta_4/\beta_0)$. Above this threshold, all approximants
considered exhibit infrared-stable fixed points that decrease in magnitude with
increasing flavour number.


title: Naturally Heavy Scalars in Supersymmetric Grand Unified Theories

abstract:
  The supersymmetric flavor, CP and Polonyi problems are hints that the
fundamental scale of the soft supersymmetry breaking parameters may be above a
TeV, in apparent conflict with naturalness. We consider the possibility that
multi-TeV scalar masses are generated by Planck- or unification-scale physics,
and find the conditions under which the masses of scalars with large Yukawa
couplings are driven, radiatively and asymptotically, to the weak scale through
renormalization group evolution. Light third generation scalars then satisfy
naturalness, while first and second generation scalars remain heavy to satisfy
experimental constraints. We find that this mechanism is beautifully realized
in the context of grand unified theories. In particular, the existence of
right-handed neutrinos plays an important role in allowing remarkably simple
scenarios. For example, for SO(10) boundary conditions with the squared masses
of Higgs scalars double those of sleptons and squarks, we find that the entire
scalar mass scale may be increased to 4 TeV at the unification scale without
sacrificing naturalness.


title: Winding Modes and Large Extra Dimensions

abstract:
  We review briefly the main features of the Large Extra Dimensions scenario in
the framework of weakly coupled Type I string theory. Kaluza-Klein (KK)
excitations of the graviton are expected, whereas no KK modes for the gauge
bosons arise if the gauge group is tied to a D3-brane. In this scenario,
typical signatures such as direct production of KK modes of the graviton at
high-energy colliders could test the size of the compactified dimensions. We
point out that contrary to what considered in the literature on the subject, in
the general case of anisotropic compactification Winding Modes of the Standard
Model gauge bosons could also be directly observable, thus further constraining
the model.


title:
Polarized light flavor sea-quark asymmetry in polarized semi-inclusive
  processes

abstract:
  We propose new formulas for extracting a difference of the polarized light
sea-quark density, $\Delta\bar d(x)-\Delta\bar u(x)$, from polarized
deep-inelastic semi-inclusive data. We have estimated the value of it from the
present experimental data measured by SMC and HERMES groups. Although the data
might suggest a violation of polarized light flavor sea-quark symmetry, the
precision of the present data is not enough for confirming it.


title: Extra Dimensions and Higgs Pair Production at Photon Colliders

abstract:
  We show that new physics effects due to extra dimensions can dramatically
affect Higgs pair production at photon colliders. We find that the cross
section due to extra dimensions with the scale $M_S$ of new physics around 1.5
TeV, the cross section can be as large as 0.11 pb (1.5pb) for monochromatic
photon collision, $\gamma \gamma \to HH$, with the collider energy $\sqrt{s} =
0.5 (1)$ TeV for Higgs mass of 100 (350) GeV. The cross section can be 3 fb
(2.7 fb) for the same parameters for collisions using photon beams from
electron or positron back scattered by laser. These cross sections are much
larger than those predicted in the Standard Model. Higgs pair production at
photon colliders can provide useful tests for new physics due to extra
dimensions.


title:
Constraints on the phase $\gamma$ and new physics from $B\to K\pi$
  Decays

abstract:
  Recent results from CLEO on $B\to K\pi$ indicate that the phase $\gamma$ may
be substantially different from that obtained from other fit to the KM matrix
elements in the Standard Model. We show that $\gamma$ extracted using $B\to
K\pi, \pi\pi$ is sensitive to new physics occurring at loop level. It provides
a powerful method to probe new physics in electroweak penguin interactions.
Using effects due to anomalous gauge couplings as an example, we show that
within the allowed ranges for these couplings information about $\gamma$
obtained from $B\to K \pi, \pi\pi$ can be very different from the Standard
Model prediction.


title:
Coefficient Functions and Open Charm Production in Deep Inelastic
  Scattering

abstract:
  It is shown that the problem of double counting in open charm production in
DIS can be solved by using the expression for DIS coefficient functions in
terms of 2PI diagrams


title:
Automatic application of successive asymptotic expansions of Feynman
  diagrams

abstract:
  We discuss the program EXP used to automate the successive application of
asymptotic expansions to Feynman diagrams. We focus on the generation of the
relevant subgraphs and the determination of the topologies for the remaining
integrals. Both tasks can be solved by using backtracking-type recursive
algorithms. In addition, an application of EXP is presented, where the
integrals were calculated using the FORM packages MINCER and MATAD.


title: Construction of nonlocal light-cone operators with definite twist

abstract:
  A systematic procedure is introduced to uniquely decompose nonlocal
LC-operators into harmonic operators of well defined geometric twist. The
method will be demonstrated for (pseudo)scalar, (axial) vector and skew tensor
bilocal quark light-ray operators


title:
Hadronic B decays: Supersymmetric enhancement and a simple spectator
  model

abstract:
  Two aspects of hadronic B decays are investigated. Firstly, the
supersymmetric enhancement of hadronic b decays by gluino penguin processes is
studied through their effect on the Wilson coefficients of the effective
Hamiltonian. Secondly, hadronization of the final state quarks is studied
through a simple phase space spectator model.


title:
Mapping Lorentz Invariance Violations into Equivalence Principle
  Violations

abstract:
  We point out that equivalence principle violations, while not dynamically
equivalent, produce the same kinematical effects as Lorentz invariance
violations for particle processes in a constant gravitational potential. This
allows us to translate many experimental bounds on Lorentz invariance
violations into bounds on equivalence principle violations. The most stringent
bound suggests that a postive signal in an E\"otv\"os experiment may be at
least seven orders of magnitude beyond current technology.


title: Once More on a Colour Ferromagnetic Vacuum State at Finite Temperature

abstract:
  The spontaneous vacuum magnetization at finite temperature is investigated in
SU(2) gluodynamics within a consistent effective potential approach including
the one-loop and the correlation correction contributions. To evaluate the
latter ones the high temperature limits of the polarization operators of
charged and neutral gluon fields in a covariantly constant magnetic field and
at high temperature are calculated.The radiation mass squared of charged gluons
is found to be positive. It is shown that the ferromagnetic vacuum state having
a field strength of order $(gH)^{1/2} \sim g^{4/3} T$ is spontaneously
generated at high temperature. The vacuum stability and some applications of
the results obtained are discussed.


title: QCD Sum-Rule Invisibility of the sigma Meson

abstract:
  QCD Laplace sum-rules for light-quark I=0,1 scalar currents are used to
investigate candidates for the lightest $q\bar q$ scalar mesons. The
theoretical predictions for the sum-rules include instanton contributions which
split the degeneracy between the I=0 and I=1 channels. The self-consistency of
the theoretical predictions is verified through a H\"older inequality analysis,
confirming the existence of an effective instanton contribution to the
continuum. The sum-rule analysis indicates that the f_0(980) and a_0(1450)
should be interpreted as the lightest $q\bar q$ scalar mesons. This apparent
decoupling of the f_0(400-1200) (or $\sigma$) and a_0(980) from the quark
scalar currents suggests a non-$q\bar q$ interpretation of these resonances.


title: Probing $c\to u\gamma$ in $B_c\to B_u^*\gamma$ decay

abstract:
  Flavour changing neutral current (FCNC) transitions $c\to u\gamma$ and $c\to
ul^+l^-$ are very rare in the standard model and present an interesting probe
for the physics beyond it. We study long distance contamination to these short
distance processes in different hadron decays. As the most suitable probe for
$c\to u\gamma$ transition we propose $B_c\to B_u^*\gamma$ decay. Its detection
at the branching ratio well above $10^{-8}$ would signal new physics. The $c\to
ul^+l^-$ transition may be probed at high $m_{ll}$ in $D\to \pi l^+l^-$. The
decays $D\to V\gamma$ and $D\to Vl^+l^-$ ($V$ is a light vector meson) are less
suitable, since they are dominated by the long distance effects.


title: Evidence that the Pomeron transforms as a non-conserved vector current

abstract:
  The detailed dependences of central meson production on the azimuthal angle
phi, t and the meson J^P are shown to be consistent with the hypothesis that
the soft Pomeron transforms as a non-conserved vector current. Further tests
are proposed. This opens the way for a quantitative description of q-qbar and
glueball production in p p -> p M p.


title: $\theta$ Vacuum in a Random Matrix Model

abstract:
  Inspired by recent lattice calculations, we model certain aspects of the
$\theta$-vacuum using a matrix model with gaussian weights. The vacuum energy
exhibits a cusp at $\theta <\pi$ that is sensitive to both the accuracy of the
numerical analysis and the maximum density of winding modes present in a finite
volume.