title:
GENTLE/4fan v.2.0 - A Program for the Semi-Analytic Calculation of
  Predictions for the Process e+e- -> 4f

abstract:
  We describe version 2.0 of the Fortran program GENTLE/4fan for the
semi-analytic computation of cross-sections and distributions in four-fermion
production in e+e- annihilation. GENTLE/4fan covers all charged current and
neutral current our-fermion final states with no identical particles, no
electrons, and no electron neutrinos in the final state. Initial state
radiation representing the most relevant quantum corrections and anomalous
triple gauge boson couplings have been included.


title: Model-Independent Z' Constraints from Measurements at the Z Peak

abstract:
  Model independent constraints on extra neutral gauge bosons are obtained from
partial decay widths of the Z_1 and forward-backward and left-right asymmetries
at the Z_1 peak. Constraints on the ZZ' mixing angle in E_6 models are
considered as special cases.


title: Correlations and Fluctuations in High-Energy Collision

abstract:
  In addition to its importance in describing high-energy processes themselves,
the dynamics of multiparticle production is part of the general field of
non-linear phenomena and complex systems. Multiparticle dynamics is one of the
rare fields of physics where higher-order correlations are directly accessible
in their full multi-dimensional characteristics under well-controlled
experimental conditions. Multiparticle dynamics, therefore, is an ideal testing
ground for the development of advanced statistical methods. Higher-order
correlations have, indeed, been observed as particle-density fluctuations.
Approximate scaling with finer resolution provides evidence for a self-similar
correlation effect. Quantum-Chromodynamics branching is a good candidate for a
dynamical explanation of these correlations in e+e- collisions at CERN/LEP and,
as expected, also of those in pp collisions at future CERN/LHC energies.
However, other sources such as identical-particle Bose-Einstein interference
effects also contribute. A particular question at the moment is the smooth
transition from the QCD branching domain (gluon interference before
hadronization) to the Bose-Einstein domain (identical-pion interference after
hadronization). Both mechanisms have clearly been observed in e+e- collisions
at CERN/LEP energies. The large amount of high-resolution data being collected
at LEP will allow the study of the genuine (i.e. non-trivial) higher-order
correlations in both domains.


title: K -> pi pi pi gamma in chiral perturbation theory

abstract:
  We present a complete analysis of K -> 3 pi gamma decays to O(p^4) in the
low-energy expansion of the Standard Model. We employ the notion of
"generalized bremsstrahlung" to take full advantage of experimental information
on the corresponding non-radiative K -> 3 pi decays.


title: One-Loop Tensor Integrals in Dimensional Regularisation

abstract:
  We show how to evaluate tensor one-loop integrals in momentum space avoiding
the usual plague of Gram determinants. We do this by constructing combinations
of $n$- and $(n-1)$-point scalar integrals that are finite in the limit of
vanishing Gram determinant. These non-trivial combinations of dilogarithms,
logarithms and constants are systematically obtained by either differentiating
with respect to the external parameters - essentially yielding scalar integrals
with Feynman parameters in the numerator - or by developing the scalar integral
in $D=6-2\e$ or higher dimensions. As an explicit example, we develop the
tensor integrals and associated scalar integral combinations for processes
where the internal particles are massless and where up to five (four massless
and one massive) external particles are involved. For more general processes,
we present the equations needed for deriving the relevant combinations of
scalar integrals.


title:
Cause of Disparity between the Results for the $n\bar{n}$ Transition
  Problem

abstract:
  We show that there is a double counting in the standard model of $n\bar{n}$
mixing in the medium, resulting in full cancellation of leading terms. The
direct calculation of $n\bar{n}$ transition, annihilation is performed. For
lower limit on the free-space $n\bar{n}$ oscillation time we get $\tau_{min}
\sim 10^{31}y$.


title: Production of Charm Quark Jets in DIS Diffractive Dissociation

abstract:
  We present a calculation of open charm quark production in diffractive deep
inelastic electron-proton scattering in a perturbative QCD framework. The cross
section is proportional to the square of the gluon density and explicitly
displays breaking of Regge factorization. Jet cross sections as well as the
charm contribution to the diffractive structure function are calculated. As a
consequence of the steep rise of the gluon density at small x the charm
contribution to $F_2^{D}$ rises with decreasing x_P.


title:
Measurements of the Delta(1232) Transition Form Factor and the Ratio
  sigma_n\sigma_p From Inelastic Electron-Proton and Electron-Deuteron
  Scattering

abstract:
  Measurements of inclusive electron-scattering cross sections using hydrogen
and deuterium targets in the region of the Delta(1232) resonance are reported.
A global fit to these new data and previous data in the resonance region is
also reported for the proton. Transition form factors have been extracted from
the proton cross sections for this experiment over the four-momentum transfer
squared range 1.64 < Q^2 < 6.75 (GeV/c)^2 and from previous data over the range
2.41 < Q^2 < 9.82 (GeV/c)^2. The results confirm previous reports that the
Delta(1232) transition form factor decreases more rapidly with Q^2 than
expected from perturbative QCD. The ratio of sigma _n \sigma_p in the
\Delta(1232) resonance region has been extracted from the deuteron data for
this experiment in the range 1.64 < Q^2 < 3.75 (GeV/c)^2 and for a previous
experiment in the range 2.4 < Q^2 < 7.9 (GeV/c)^2. A study has been made of the
model dependence of these results. This ratio sigma_n\sigma_p for \Delta(1232)
production is slightly less than unity, while sigma_n\sigma_p for the
nonresonant cross sections is approximately 0.5, which is consistent with deep
inelastic scattering results.


title: Testing Chiral Symmetry Breaking at DAPHNE

abstract:
  The spontaneous breakdown of the chiral symmetry of the QCD Lagrangian
ensures that $\pi\pi$ interactions are weak at low energies. How weak depends
on the nature of explicit symmetry breaking. Measurements of $K_{e4}$ decays at
DA$\Phi$NE will provide a unique insight into this mechanism and test whether
the $q{\overline q}$--condensate is large or small.


title: Hybrids as a Signature of Quark-Gluon Plasma

abstract:
  We show that the dynamics of the Quark-Gluon Plasma is such that during
hadronization the creation of hybrids will predominate over the creation of
mesons, giving a novel signature of the existence of QGP. At T = 0 the
$(q\bar{q}g)$ hybrids are known to decay strongly into a pair of mesons. We
find that at temperatures relevant to the QGP, this channel is forbidden. This
would lead to significant modifications of the photonic signals of the QGP.


title: Which scalar meson is the glue-state ?

abstract:
  Preliminary results of a work in collaboration with M.R. Pennington are
presented. Extending a scheme introduced by Tornqvist, we investigate a
dynamical model in which the spectrum of scalar mesons can be derived, with the
aim of locating the lightest glue-state. Adding hadronic interaction
contributions to the bare propagator, to `dress' the bare quark-model $q
\overline q$ states, we are able to write the amplitudes and the phase shifts
in the approximation in which scalar resonances decay only into two
pseudoscalar channels. The fit of these quantities to experimental data gives a
satisfactory understanding of how hadronic interactions modify the underlying
`bare' spectrum. In particular, we examine the case in which a glue-state is
introduced into the model.


title:
Systematic effects in the determination of the piNN Coupling from pbar p
  -> nbar n differential cross section

abstract:
  We show that the $\pi NN$ coupling constant extracted model-independently
from $\bar pp$ charge exchange is subject to a systematic correction, and, more
importantly, that the strong absorption in the critical region prevents a
determination of the coupling constant to high precision using this process.
This attenuates the possible conflict with the value determined from the np
charge exchange cross sections.


title: Large Charmless Yield in B Decays and Inclusive B Decay Puzzles

abstract:
  In recent studies of inclusive $B$ decays, it has been suggested that either
$B$ mesons decay much more copiously to final states with no open charm than
currently assumed, or $B(D^0 \to K^-\pi^+)$ has to be reduced significantly.
This note takes the experimental $B(D^0 \to K^-\pi^+)$ at its face value and
estimates $B(b\to$ no open charm) using complementary methods: one accounts for
the $c$ quark in $b\to c$ transitions, the other accounts for the $\bar c$
quark in $b\to c\bar c s$ transitions. Through cancellation of errors, the
average gives our best estimate of $B(b\to$ no open charm), and the difference
measures the consistency. The results of the methods are consistent with each
other, strongly suggesting a much enhanced $B(b\to$ no open charm). This
observation indicates that non-perturbative QCD effects are probably causing a
sizable fraction of the $b\to c\bar cs$ transitions to be seen as charmless
$b\to s$ processes, contrary to smaller traditional expectations. This
mechanism has generally been overlooked and may explain the existing
experimental data within the framework of the standard model. We then briefly
discuss implications on baryon production governed by $b\to c\bar cs$
processes, rare hadronic $B$ decays and CP violation studies.


title:
Large-N Baryons, Chiral Loops, and the Emergence of the Constituent
  Quark

abstract:
  Meson loop corrections to baryon axial currents are computed in the 1/N
expansion. It is already known that the one-loop corrections are suppressed by
a factor 1/N; here it is shown that the two-loop corrections are suppressed by
(1/N)^2. To leading order, these corrections are exactly what would be
calculated in the constituent quark model. Some applications are discussed.


title: The Bilocal Effective Action for Mesons in Large-N QCD

abstract:
  The bilocal effective action is developed as a viable tool to study mesons in
the large-N limit of QCD. Several results from current algebra are derived in a
new way using this action. The question of gauge invariance is discussed in an
appendix


title: Single top quarks at the Fermilab Tevatron

abstract:
  We present a calculation of the single top quark cross section for
proton-antiproton interactions with sqrt(s) = 1.8 TeV at the Fermilab Tevatron
collider. We examine the effects of top mass, parton distribution functions,
QCD scale, and collision energy, on each of the component production
mechanisms, and study the kinematic distributions for standard model
electroweak production. At the upgraded Tevatron with sqrt(s) = 2.0 TeV and
high luminosity, it will be possible to test the nature of the Wtb coupling
using single top production. We estimate the sensitivity to measure the single
top cross section, and thus to directly measure V_tb and the top quark partial
width. We show what happens to the V_tb measurement when an anomalous (V+A)
component is added to the Wtb coupling, and how the top quark polarization
affects the kinematic distributions.


title:
Hard diffractive electroproduction, transverse momentum distribution and
  QCD vacuum structure

abstract:
  We study the impact of the "intrinsic" hadron transverse momentum on the
pre-asymptotic behavior of the diffractive electroproduction of longitudinally
polarized $ \rho$-meson. Surprisingly, we find the onset of the asymptotic
regime in this problem to be rather low, Q^2 ~ 10 GeV^2 where power corrections
due to the transverse momentum do not exceed 20 % in the amplitude. This
drastically contrasts with exclusive amplitudes where the asymptotics starts at
much higher Q^2 = 50 - 100 GeV^2. The sources of such unexpected behavior are
traced back to some general (the quark-hadron duality) as well as more silent
(properties of higher dimensional vacuum condensates) features of QCD.


title: New Mechanisms of Gauge-Mediated Supersymmetry Breaking

abstract:
  We introduce new mechanisms for the communication of supersymmetry breaking
via gauge interactions. These models do not require complicated dynamics to
induce a nonvanishing F term for a singlet. The first class of models
communicates supersymmetry breaking to the visible sector through a ``mediator"
field that transforms under both a messenger gauge group of the dynamical
supersymmetry breaking sector and the standard model gauge group. This model
has distinctive phenomenology; in particular, the scalar superpartners should
be heavier by at least an order of magnitude than the gaugino superpartners.
The second class of models has phenomenology more similar to the ``standard"
messenger sectors. A singlet is incorporated, but the model does not require
complicated mechanisms to generate a singlet F term. The role of the singlet is
to couple fields from the dynamical symmetry breaking sector to fields
transforming under the standard model gauge group. We also mention a potential
solution to the $\mu$ problem.


title: Density fluctuation in extended inflation

abstract:
  We examine the calculation of density perturbation at large scales in the
inflationary scenario. The formula for its magnitude is reviewed from first
principles and applied to the original model of extended inflation. Our
estimate is an order of magnitude bigger than the earlier ones due to the
difference in the time at which the primordial fluctuation is evaluated and to
the inclusion of terms neglected earlier in the standard formula for density
perturbation.


title: Propagation of Majorana fermions in hot plasma

abstract:
  The properties of Majorana fermions in hot plasma are studied. One-loop
resummed propagator, dispersion relations and their interpretation are
discussed. It is shown that particle and hole -like solutions appear as in
Dirac/chiral fermion case. The dispersion relations are, however, crucially
different. We find that, in presence of a large zero temperature bare mass,
hole -like excitations posses a negligible effective mass. As an example of
real application, we consider the neutralinos in the minimal supersymmetric
extension of the standard model and argue that for realistic values of the soft
supersymmetry breaking masses the existence of practically massless hole -like
excitations have a considerable effect on the thermal properties, e.g. the
thermalization rate, of particles interacting with these Majorana excitations.


title:
A status report concerning theoretical predictions for various kaon
  decays

abstract:
  A short overview of theoretical predictions for various kaon decays is
presented. Particular attention is devoted to pure and radiative nonleptonic
decays in the framework of Chiral Perturbation Theory. The relevance of KLOE's
future results to improve our knowledge of kaon physics and more generally of
the Standard Model at low energy is also emphasized.


title: Effective SU(2)_L x U(1) theory and the Higgs boson mass

abstract:
  We assume the stability of vacuum under radiative corrections in the context
of the standard electroweak theory. We find that this theory behaves as a good
effective model already at cut off energy scales as low as 0.7 TeV. This
stability criterion allows to predict m_H= 318 +- 13 GeV for the Higgs boson
mass.


abstract:
  A rigorous evaluation of the Landau-Pomeranchuk-Migdal effect for finite-size
targets is performed within the path integral approach previously developed in
ref. [4]. The bremsstrahlung rate in QED is expressed through a solution of a
two-dimensional Schr\"odinger equation with an imaginary potential. The
boundary condition for this solution is formulated in terms of a product of the
light-cone electron--photon wave function and the dipole cross section for
scattering of $e^{+}e^{-}$ pair off an atom. Numerical calculations are
performed for homogeneous and structured targets. Our predictions for the
homogeneous target agree well with the photon spectrum measured recently at
SLAC with 25 GeV electrons. The spectra obtained for the structured two segment
targets exhibit the interference minima and maxima.


title: Some aspects of thermal field theories

abstract:
  Different formalisms used in the perturbative approach to Thermal Field
Theory (TFT) are briefly reviewed. The rate of production of a virtual photon
in a quark-gluon plasma is then discussed to illustrate some features of TFT
before introducing the Hard Thermal Loop resummation which improves the
behaviour of the theory in the infrared sector. Some of the successes of this
appraoch are described before turning to the problems associated to the
undamped transverse gluon oscillations and the light-cone singularities arising
when on-shell and/or massless particles are involved.


title:
Enhanced CP Violation with $B\to K D^0 (\overline D^0)$ Modes and
  Extraction of the CKM Angle gamma

abstract:
  The Gronau-London-Wyler (GLW) method extracts the CKM angle $\gamma$ by
measuring $B^\pm$ decay rates involving $D^0/\overline D^0$ mesons. Since that
method necessitates the interference between two amplitudes that are
significantly different in magnitude, the resulting asymmetries tend to be
small. CP violation can be greatly enhanced for decays to final states that are
common to both D^0 and $\overline D^0$ and that are not CP eigenstates. In
particular, large asymmetries are possible for final states f such that $D^0\to
f$ is doubly Cabibbo suppressed while $\overline D^0\to f$ is Cabibbo allowed.
The measurement of interference effects in two such modes allows the extraction
of $\gamma$ without prior knowledge of $Br(B^-\to K^- \overline D^0)$, which
may be difficult to determine due to backgrounds.


title:
On effective interactions containing $\partial . W^\pm$ and $\partial .
  Z$ factors

abstract:
  The effects of effective interactions containing the factors $\partial \cdot
W^\pm$ and $\partial \cdot Z$ is studied within a consistent effective
Lagrangian formalism. It is shown that such terms are redundant


title:
$O(\alpha)$ QED Corrections to Neutral Current Polarized Deep-Inelastic
  Lepton-Nucleon Scattering

abstract:
  The $O(\alpha)$ leptonic QED corrections to neutral current polarized deep
inelastic lepton-nucleon scattering are calculated in leptonic variables both
for the case of longitudinal and transverse nucleon polarization. The results
of the complete calculation are compared with the corresponding leading log
expressions. Numerical results are presented for the corrections in the
kinematic range of the HERMES experiment and possible future polarized proton
beam experiments at HERA.


title:
Signatures of Spontaneous Breaking of R-Parity in Gluino Cascade Decays
  at LHC

abstract:
  We study the pattern of gluino cascade decays in a class of supersymmetric
models where R-parity is spontaneously broken. We give a detailed discussion of
the R-parity violating decays of the lightest neutralino, the second lightest
neutralino and the lightest chargino. The multi-lepton and same-sign dilepton
signal rates expected in these models are compared with those predicted in the
Minimal Supersymmetric Standard Model. We show that these rates can be
substantially enhanced in broken R-parity models.


title: CPT Violation and Baryogenesis

abstract:
  We examine the effects on baryogenesis of spontaneous CPT violation in a
string-based scenario. Under suitable circumstances, certain CPT-violating
terms can produce a large baryon asymmetry at the grand-unified scale that
reduces to the observed value via sphaleron or other dilution mechanisms.


title:
Using the decay $b\to s\gamma$ to bound the chromomagnetic dipole moment
  of the top quark

abstract:
  Using the CLEO data for $b\to s\gamma$, we constrain the chromomagnetic
dipole moment of the top quark within the context of a decoupling effective
Lagrangian approach. Our results are in agreement with the results obtained for
the $e^+e^-$ and hadron colliders.


title: Phenomenology of neutral heavy leptons

abstract:
  We continue our previous work on the flavour-conserving leptonic decays of
the Z boson with neutral heavy leptons (NHL's) in the loops by considering box,
vertex, and self-energy diagrams for the muon decay. By inclusion of these
loops (they contribute to the input parameter M_W) we can probe the full
parameter space spanned by the so-called flavour-conserving mixing parameters
ee_(mix), \mu\mu_(mix), \tau\tau_(mix) in a superstring-inspired model of
neutrino mass. We compare the results of our analysis with the existing work in
this field and conclude that flavour-conserving decays have certain advantages
over traditionally considered flavour-violating ones.


title:
Extended Gauge Sectors at Future Colliders: Report of the New Gauge
  Boson Subgroup

abstract:
  We summarize the results of the New Gauge Boson Subgroup on the physics of
extended gauge sectors at future colliders as presented at the 1996 Snowmass
workshop. We discuss the direct and indirect search reaches for new gauge
bosons at both hadron and lepton colliders as well as the ability of such
machines to extract detailed information on the couplings of these particles to
the fermions and gauge bosons of the Standard Model. [To appear in the
Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy
Physics-Snowmass96, Snowmass, CO, 25 June-12 July, 1996.]


title: Heavy Baryon Mixing in Chiral Perturbation Theory

abstract:
  We discuss the SU(3) and heavy quark spin-symmetry breaking mixing between
the Xi_c and Xi'_c charmed baryons. Chromomagnetic hyperfine interactions are
the leading source of spin-symmetry breaking and together with the SU(3)
breaking mass differences between the lightest pseudo-Goldstone bosons gives
the leading contribution to the mixing. Such contributions are computed in
chiral perturbation theory and compared to quark model expectations. We also
compute the leading contribution to the semileptonic decay Xi_b -> Xi'_c l nu
at zero recoil, and find that it is an order of magnitude smaller than naive
power counting would suggest. It appears that Xi_b -> Xi'_c l nu is dominated
by incalculable counterterms, and we discuss the implications for quark models
based on the essential role of hyperfine interactions.


title:
Anomalous U(1) and low-energy physics: the power of D-flatness and
  holomorphy

abstract:
  In models with an anomalous abelian symmetry broken at a very large scale, we
study which requirements to impose on the anomalous charges in order to prevent
standard model fields from acquiring large vacuum expectation values. The use
of holomorphic invariants to study D-flat directions for the anomalous
symmetry, proves to be a very powerful tool. We find that in order to forbid
unphysical vacuum configurations at that scale, the superpotential must contain
many interaction terms, including the usual Yukawa terms. Our analysis suggests
that the anomalous charge of the \mu-term is zero. It is remarkable that,
together with the seesaw mechanism, and mass hierarchies, this implies a
natural conservation of R-parity.


title: Spin Dependent Fragmentation Functions For Baryons in a Diquark Model

abstract:
  The perturbative QCD calculation of heavy quark fragmentation into a heavy
meson is extended to predict fragmentation into heavy flavor baryons. This is
accomplished by implementing the quark-diquark model of the baryons. Several
diquark form factors are used to enable the integration over the virtual heavy
quark momentum. The resulting spin independent functions for charmed quarks to
fragment into charmed baryons with spin 1/2 and 3/2 are compared with recent
data. Predictions are made for the spin dependent fragmentation functions as
well, particularly for the functions $\hat{g}_1$ in the case of spin 1/2
baryons.


title:
Prediction on CP Violation in Long Baseline Neutrino Oscillation
  Experiments

abstract:
  We predict CP violation in the long baseline accelerator experiments taking
into consideration the recent LSND data and the atmospheric neutrino data. The
estimated upper bound of CP violation is 0.006, which may be observable in the
long baseline accelerator experiments. It is found that the upper bound
increases to 0.01 if the LSND data is excluded. The matter effect, which is not
CP invariant, is found to be very small in the case we consider.


title: Two-Body Dirac Equation and Its Wave Function at the Origin

abstract:
  A relativistic equation is deduced for the bound state of two particles, by
assuming a proper boundary condition for the propagation of the negative-energy
states. It reduces to the (one-body)Dirac equation in the infinite limit of one
of the constituent mass. It also has the symmetries to assure the existence of
the anti-bound-state with the same mass. The interaction
kernel(pseudo-potential) is systematically constructed by diagonalizing the
Hamiltonian of the background field theory, by which the retardation effects
are included in the interaction. Its wave function at the origin(WFO) behaves
properly in a manner suggested by the covariant field theory. The equation can
well be applied in the heavy quark effective theory.


title:
CP Violation and the Role of Electroweak Penguins in Non-leptonic B
  Decays

abstract:
  The phenomenon of CP violation in the B system and strategies for extracting
CKM phases are reviewed. We focus both on general aspects and on some recent
developments including CP-violating asymmetries in B_d decays, the B_s system
in light of a possible width difference $\Delta\Gamma_s$, charged B decays, and
SU(3) relations among certain transition amplitudes. In order to describe the
relevant non-leptonic B decays, low energy effective Hamiltonians calculated
beyond the leading logarithmic approximation are used. Special emphasis is
given to the role of electroweak penguin operators in such transitions. These
effects are analyzed both within a general framework and more specifically in
view of the theoretical cleanliness of methods to determine CKM phases.
Strategies for obtaining insights into the world of electroweak penguins are
discussed.


title:
Some Implications of a Supersymmetric Model with R-Parity Breaking
  Bilinear Interactions

abstract:
  We investigate a supersymmetric scenario where R-parity is explicitly broken
through a term bilinear in the lepton and Higgs superfields in the
superpotential. We show that keeping such a term alone can lead to trilinear
interactions, similar to those that are parametrized by $\lambda$-and
${\lambda}'$ in the literature, involving the physical fields. The upper limits
of such interactions are predictable from the constraints on the parameter
space imposed by the lepton masses and the neutrino mass limits. It is observed
that thus the resulting trilinear interactions are restricted to values that
are smaller than the existing bounds on most of the $\lambda$-and
${\lambda}'$-parameters. Some phenomenological consequences of such a scenario
are discussed.


title:
Thermal Dileptons as a Possible Source of the Soft Dilepton Enhancement
  Measured in A-A Collisions at SPS Energies

abstract:
  The production of soft dileptons in a thermal mesonic medium is discussed in
the context of recent CERN experimental data reported by the CERES
Collaboration. We do not intend to give a general and critical review, but
instead concentrate mainly on our approach, however, incorporating many of the
recent attempts in the literature. We calculate the contributions to the
dilepton yield arising from pion annihilation and $\pi -\rho$ scattering. It is
shown that thermal dileptons from $\pi -\rho$ scattering give a significant
contribution to the low-mass yield, however, it can only partly account for the
experimentally observed soft dilepton excess seen in S-Au and Pb-Au collisions
at SPS energy. The out off-equilibrium effects as well as a dropping vector
meson mass are discussed in the context of the thermal dilepton yield. We
emphasize, following the results of Li, Ko, and Brown, that, until now, the
best way to provide a quantitative explanation of the observed enhancement of
low-mass dileptons by the CERN experiments is the assumption of a decreasing
vector meson mass in a high density thermal medium.


title: Consistent Treatment of Charm Evolution in Deep Inelastic Scattering

abstract:
  We present a formulation which allows heavy quark (c, b, ...) mass effects to
be explicitly incorporated in both the coefficient functions and the splitting
functions in the parton evolution equations. We obtain a consistent procedure
for evolution through the threshold regions for c anti-c and b anti-b
production in deep inelastic scattering, which allows the prediction of the
charm and bottom quark densities. We use the new formulation to perform a
next-to-leading order global parton analysis of deep inelastic and related hard
scattering data. We find that the optimum fit has alpha_S(M_Z^2) = 0.118. We
give predictions for the charm components of the proton structure functions F_2
and F_L as functions of x and Q^2 and, in particular, find that F_2^c is in
good agreement with the existing measurements. We examine the Q^2 range of
validity of the photon-gluon fusion model for c anti-c electroproduction. We
emphasize the value of a precision measurement of the charm component F_2^c at
HERA.


title: Non-perturbative correlation masses in the hot electroweak phase

abstract:
  The effective action describing the long range fluctuations in the high
temperature phase of the electroweak standard theory is a strongly coupled
SU(2)-Higgs-model in three dimensions. We outline in detail a model in which
the spatial correlation scales in this phase are calculated as inverse
relativistic bound state masses. Selection rules for these states are derived.
The correlation masses are calculated by evaluating the bound state Green's
function. The scalar-scalar-potential and its influence on the masses is
investigated. The predictions for the correlation masses agree very well with
the lattice data available now.


title: Exploring the supersymmetric parameter space by direct search for WIMPs

abstract:
  It is shown that the new data of the DAMA/NaI detector, combined with recent
calculations of nuclear structure functions, provide the most stringent upper
bounds on the WIMP-nucleon cross-section both for spin-dependent and for scalar
interactions. It is proved that, for the first time, data from an experiment of
direct search for WIMPs allow the exploration of a region of the supersymmetric
parameter space not yet fully investigated at accelerators.


title: Strong CP and Low-energy Supersymmetry

abstract:
  A spontaneously-broken CP provides an alternative to the KM mechanism for CP
violation with the advantage that the strong CP problem is solved. We consider,
for such a model with a new gauged U(1), the incorporation of low-energy
supersymmetry and find the constraints on alignment and squark degeneracy. The
conclusion is that although the $\bar{\theta}$ constraints are much less severe
than in other generic schemes with supersymmetry breaking and spontaneous CP
violation, one restriction remains stronger than needed in the MSSM for
suppression of FCNC.


title:
Mean-field treatment of the linear sigma model in dynamical calculations
  of DCC observables

abstract:
  Approximate mean-field equations of motion for the classical chiral field are
developed within the linear sigma model by means of a Hartree factorization.
Both the approximate and the unapproximated equations of motion are augmented
with a Rayleigh cooling term to emulate a uniform expansion, thereby allowing
the extraction of observables relevant to the detection of disoriented chiral
condensates, specifically the pion power spectrum, the pion correlation
function, and the distribution of the neutral pion fraction. While the
mean-field dynamics appears to be sufficiently accurate to be practically
useful, the results also illustrate some difficulties associated with
identifying the phenomenon experimentally.


title: A Monte Carlo Solution to the BFKL Equation

abstract:
  A simple solution to the BFKL equation is obtained as a series in the number
of real gluons emitted with transverse momentum greater than some small cutoff
$\mu$. This solution reveals physics inside the BFKL ladder which is hidden in
the standard inclusive solution, and lends itself to a straightforward Monte
Carlo implementation. With this approach one can explore new useful physical
observables, which are shown to be independent of the cutoff $\mu$. In
addition, this approach allows the imposition of kinematic constraints (such as
energy conservation) which are important at finite energies. The distribution
of $\sum E_\perp$ of particles in a central rapidity bin between two
widely-spaced jets is presented as an example.


title: Valence parton dencity in the pion from QCD sum rules

abstract:
  We calculate the leading twist valence quark distribution in the pion in the
franework of QCD sum rules with nonlocal condensates. Particular attention has
been paid to the correct account of the bilocal power corrections.


title: The pseudoscalar and vector excited mesons in the U(3)*U(3) chiral model

abstract:
  A chiral U(3)*U(3) Lagrangian containing, besides the usual meson fields,
their first radial excitations is constructed. The Lagrangian is derived by
bosonization of the Nambu-Jona-Lasinio quark model with separable non-local
interactions, with form factors corresponding to 3-dimensional ground and
excited state wave functions. The spontaneous breaking of chiral symmetry is
governed by the NJL gap equation. The first radial excitations of the pions,
kaons and vector meson nonet are described with the help of five different form
factors. Each form factor contains only one arbitrary parameter. The masses of
these meson states and the weak decay constants $F_{\pi'}, F_K and F_{K'}$ are
calculated.


title: Masses, decays and mixings of gluonia in QCD

abstract:
  We compute the masses and decay widths of gluonia using QCD spectral sum
rules and low-energy theorems. In the scalar sector, one finds a gluonium
having a mass $M_G=(1.5\pm 0.2)$ GeV, which decays mainly into the $U(1)_A$
channels $\eta\eta'$ and 4$\pi^0$. However, for a consistency of the whole
approach, one needs broad-low mass gluonia (the $\sigma$ and its radial
excitation), which couple strongly to the quark degrees of freedom similarly to
the $\eta'$ of the $U(1)_A$ sector. Combining these results with the ones for
the $\bar qq$ quarkonia, we present maximal quark-gluonium mixing schemes,
which can provide quite a good description of the complex spectra and various
decay widths of the observed scalar mesons
$\sigma(1.0),f_0(0.98),f_0(1.37),f_0(1.5)$ and $f_J(1.71)$. In the tensor
sector, the gluonium mass is found to be $M_T\simeq (2.05\pm 0.19)$ GeV, which
makes the $\zeta(2.2)$ a good $2^{++}$ gluonium candidate, even though we
expect a rich population of $2^{++}$ gluonia in this region. In the
pseudoscalar channel, the gluonium mass is found to be $M_P\simeq (2.05\pm
0.19)$ GeV, while we also show that the $E/\iota(1.44)$ couples more weakly to
the gluonic current than the $\eta'$, which can favour its interpretation as
the first radial excitation of the $\eta'(0.96)$.


title:
The effectiveness of the local potential approximation in the
  Wegner-Houghton renormalization group

abstract:
  The non-perturbative Wegner-Houghton renormalization group is analyzed by the
local potential approximation in O(N) scalar theories in d-dimensions $(3\leq
d\leq 4)$. The leading critical exponents \nu are calculated in order to
investigate the effectiveness of the local potential approximation by comparing
them with the other non-perturbative methods. We show analytically that the
local potential approximation gives the exact exponents up to $O(\epsilon )$ in
\epsilon-expansion and the leading in 1/N-expansion. We claim that this
approximation offers fairly accurate results in the whole range of the
parameter space of N and d. It is a great advantage of our method that no
diverging expansions appear in the procedure.


title:
Non-Perturbative Renormalization Group Analysis of the Chiral Critical
  Behaviors in QED

abstract:
  We study the chiral critical behaviors of QED by using Non-Perturbative
Renormalization Group (NPRG). Taking account of the non-ladder contributions,
our flow equations are free from the gauge parameter ($\alpha$) dependence. We
clarify the chiral phase structure, and calculate the anomalous dimension of
$\bar\psi\psi$, which is enhanced compared to the ladder approximation. We find
that the cutoff scheme dependence of the physical results is very small.


title: Status of 2HDM with a Light Higgs Particle

abstract:
  Present data do not rule out the light neutral Higgs particle h or A with
mass below 40--50 GeV in the framework of the general 2HDM ("Model II"). The
status of this model in a light of existing LEP I data and a potential of the
new muon experiment (g-2), the measurement of photon-gluon and gluon-gluon
fusion at HERA as well as photon-photon fusion at low energy gamma gamma NLC is
discussed.


title: Z' in the 3-3-1 model

abstract:
  Phenomenological implications of the Z' in SU(3)xSU(3)xU(1) extension of the
standard model are studied. The model improves the fit for R_b as well as the
high E_T jet cross section observed by CDF.


title: A Note on the QCD Vacuum Tensor Susceptibility

abstract:
  We consider the procedure of determination of induced quark condensates in
the QCD sum rule approach. It is noted that the previous estimations of this
value were very rough. It is shown, that the detailed analyses of this
parameter of QCD vacuum leads to the conclusion that the value of the tensor
susceptibility has opposite sign and much larger than estimations which were
obtained before. The reason of this contradiction is discussed. It is noted
that naive ways of determination of induced condensates may lead to wrong
results. The case of tensor susceptibility is the example demonstrating the
importance of the procedure which is applied for calculation of such
condensates. New results for the nucleon tensor charge are presented. The
tensor charge is related to the first momentof the transversity distribution
function $h_1(x)$.


title: Heavy Baryon Transitions in a Relativistic Three-Quark Model

abstract:
  Exclusive semileptonic decays of bottom and charm baryons are considered
within a relativistic three-quark model with a Gaussian shape for the
baryon-three-quark vertex and standard quark propagators. We calculate the
baryonic Isgur-Wise functions, decay rates and asymmetry parameters.


title: Large tan beta in Gauge-Mediated SUSY-Breaking Models

abstract:
  We explore some topics in the phenomenology of gauge-mediated SUSY-breaking
scenarios having a large hierarchy of Higgs VEVs, $v_U/v_D = tan\beta \gg 1$.
Some motivation for this scenario is first presented. We then use a systematic,
analytic expansion (including some threshold corrections) to calculate the
$\mu$ parameter needed for proper electroweak breaking and the radiative
corrections to the B parameter, which fortuitously cancel at leading order. If
B = 0 at the messenger scale then $tan\beta$ is naturally large and calculable;
we calculate it. We then confront this prediction with classical and quantum
vacuum stability constraints arising from the Higgs-slepton potential, and
indicate the preferred values of the top quark mass and messenger scale(s). The
possibility of vacuum instability in a different direction yields an upper
bound on the messenger mass scale complementary to the familiar bound from
gravitino relic abundance. Next, we calculate the rate for $b\to s\gamma$ and
show the possibility of large deviations (in the direction currently favored by
experiment) from standard-model and small $tan\beta$ predictions. Finally, we
discuss the implications of these findings and their applicability to future,
broader and more detailed investigations.


title: Nucleon Form Factors in a Relativistic Three-Quark Model

abstract:
  We report the calculation of electromagnetic form factors of nucleons within
a relativistic three-quark model with Gaussian shape for the nucleon-quark
vertex. The allowed region for two adjustable parameters, the range parameter
$\Lambda_N$ in the Gaussian and the constituent quark mass $m_q$, is obtained
from fitting the data for magnetic moments and electromagnetic radii of
nucleons. It is found that their values calculated with $m_q$=420 MeV and
$\Lambda_N$=1.25 GeV agree very well with the experimental data. It is turned
out that the electric proton and magnetic nucleon form factors fall faster than
the dipole fit of the experimental data for momentum transfers $0\le Q^2\le 1$
GeV$^2$.


title: On the spin-orbit force in the Wilson loop context

abstract:
  The Green function of the quark-antiquark system in the confining background
field is analysed using the Feynman-Schwinger formalism. The Hamiltonian for
the case of massive spinning quarks is obtained in the form containing
essentially nonhermitian part. The eigenvalue problem for such type of the
Hamiltonian is discussed, and it is shown that no complex eigenvalues arise.
The corresponding no nunitary Foldy-Wouthuysen transformation is performed to
obtain the hermitian Hamiltonian, and the standard spin-orbit interaction term
is recovered.


title:
QCD Sum Rules and the Determination of Leading Twist Non-Singlet
  Operator Matrix Elements

abstract:
  We use QCD sum rules to determine directly the leading-twist non-singlet
operator matrix elements based on calculations of three-point correlator
functions in configuration space. We find a different result from that obtained
by integrating the structure functions' expressions obtained by Belyaev and
Ioffe based on calculations of four-point correlators in momentum space. The
origin of this discrepancy remains unclear.


title: Effective Messenger Sector from Dynamical Supersymmetry Breaking

abstract:
  In the framework of the dynamical supersymmetry breaking we construct the
messenger sector as the effective theory of supersymmetry breaking sector,
which is based on SU(3) \times SU(2) model of Affleck, Dine and Seiberg. In our
model, messenger superfields with non-renormalizable interaction are contained.
By minimizing the scalar potential, we show that the supersymmetry breaking can
be communicated to the visible sector without breaking QCD color. In this model
there appear various scales. Supersymmetry breaking scale turns out to be the
intermediate scale ( \sim 10^{10} GeV ) between the GUT scale and the soft
supersymmetry breaking scale.


title:
High Energy Photon Deep Inelastic Scattering at Small and Large Q^2 with
  Soft Plus Hard Pomeron

abstract:
  We show how the sum of a hard singularity, $F_{2H}(x,Q^2_0)\sim x^{-\lambda}$
and a soft Pomeron $F_{2P}(x,Q^2_0)\sim Const.$ for the singlet piece of the
structure function $F_{2S}=F_{2H}+F_{2P}$ for $Q_0^2\sim a few GeV^2$, plus a
saturating expression for the strong coupling,
$\tilde{\alpha}_s(Q^2)=4\pi/\beta_0 log[(Q^2+\Lambda^2)/\Lambda^2]$ give an
excellent description of experiment
  i) For small Q^2, $0\lsim Q^2\leq 8.5 GeV^2$, and
  ii) For large Q^2, $10\lsim Q^2\leq 1 500 GeV^2$ if evolved with QCD. The x
range is $6\times10^{-6}\lsim x \lsim 0.04$. The description for low Q^2
implies self-consistent values for the parameters in the exponents of x both
for singlet and nonsinglet. One has to have $\alpha_{\rho}(0)=0.48$ and
$\lambda=0.470 [\alpha_P(0)=1.470]$, in uncanny agreement with other
determinations of these parameters, and in particular the results of the large
Q^2 fits. The fit to data is so good that we may look for signals of a ``triple
Pomeron" vertex, for which some evidence is found.


title: Supersymmetric Scalar Masses, Z', and E(6)

abstract:
  Assuming the existence of a supersymmetric U(1) gauge factor at the TeV
energy scale (motivated either by the superstring-inspired E_6 model or
low-energy electroweak phenomenology), several important consequences are
presented. The two-doublet Higgs structure at the 100 GeV energy scale is shown
to be different from that of the Minimal Supersymmetric Standard Model (MSSM).
A new neutral gauge boson Z' corresponding to the extra U(1) mixes with the Z.
The supersymmetric scalar quarks and leptons receive new contributions to their
masses from the spontaneous breaking of this extra U(1). The assumption of
universal soft supersymmetry breaking terms at the grand-unification energy
scale implies a connection between the U(1) breaking scale and the ratio of the
vacuum expectation values of the two electroweak Higgs doublets.


title:
Notes on the Kinematic Structure of the Three-Flavor Neutrino
  Oscillation Framework

abstract:
  These notes present a critique of the standard three-flavor neutrino
oscillation framwork. The design proposal of the MINOS at Fermilab based on a
two mass eigenstate framework may require serious reconsideration if there is
strong mixing between all three flavors of neutrinos. For the LSND and KARMEN
neutrino oscillation experiments, the amplitude of neutrino oscillation of the
``one mass scale dominance''framework vanishes for certain values of mixing
angles as a result of opposite signs of two equal and opposite contributions.
Recent astronomical observations leave open the possibility that one of the
neutrino mass eigenstates may be non-relativistic in some instances. Neutrino
oscillation phenomenology with a superposition of two relativistic, and one
non-relativistic, mass eigenstates is constructed. It is concluded that if the
transition from the non-relativistic to the relativistic regime happens for
energies relevant to the Reactor and the LSND neutrino oscillation experiments
then one must consider an ab intio analysis of the existing data.


title: Charge Distribution in Chiral Pion Bremsstrahlung

abstract:
  It is argued that distribution over the number of charged and neutral soft
chiral pions are very broad if they are emitted coherently.


title: Cross-Symmetric Expansion of $\pi \pi$ Amplitude Near Threshold

abstract:
  The near-threshold expansion of the $\pi \pi$ amplitude is developed using
the crossing-covariant independent variables. The independent threshold
parameters entering the real part of the amplitude in an explicitly
Lorentz-invariant way are free from restrictions of isotopic and crossing
symmetries. Parameters of the expansion of the imaginary part are recovered by
the perturbative unitarity relations.


title: Baryon Structure in a Covariant Diquark-Quark Model

abstract:
  The baryon structure is investigated in a covariant diquark-quark model. In
this approach baryons emerge as relativistic bound states of a constituent
quark and a $0^{+}$ or $1^{+}$ diquark. After solving the Bethe-Salpeter
Equation for the scalar diquark quark system in ladder approximation we couple
various external currents to the constituents of the baryon to probe its
internal structure. The quark and the diquarks are assumed to be confined which
is implemented by suitable choices for the propagators. This leads to
nontrivial vertex functions between the constituents and the external current.
Baryonic matrix elements are then evaluated to extract observable formfactors.


title: Charge Distribution in Soft Chiral Pion Bremsstrahlung

abstract:
  Bremsstrahlung of soft chiral pions in high-energy processes is considered.
The distribution over number of neutral and charged pions is shown to obey the
inverse square root law. This law is argued to be generic for multiple coherent
production of soft chiral pions.


title: Enhanced Correlations and Wide Charge Distributions in Pion Production

abstract:
  Unusual phenomena in pion production are considered.It is argued that pions
may be in a squeezed state having enhanced identical pion correlations. Charge
distribution in soft chiral pion bremsstrahlung is shown to be very broad.


title:
QCD Sum Rule Analysis of Leading Twist Non-Singlet Operator Matrix
  Elements

abstract:
  We use QCD sum rules to determine the difference between moments of the
non-singlet structure functions. This combination decouples from the singular
behaviour of the structure functions near x=1 as calculated in the quark-gluon
basis and thus should lead to improved sum rule predictions. However, we find
there are still very large errors due to higher order corrections. In order to
refine the error analysis, we study the effect of renormalon ambiguities on our
QCD sum rules results.


title: The Cold Plus Hot Dark Matter Model From Supersymmetric Inflation

abstract:
  The cold plus hot dark matter (CHDM) model is arguably the best theory we
currently have for a consistent description of the observed large scale
structure formation. This is especially true if the primordial density
fluctuations are assumed to be essentially scale invariant, in which case a
mixture with 20-25 % HDM, 5- 10 % baryons, and the rest in CDM correctly
predicted (in 1989) the quadrupole anisotropy measured a few years later by the
COBE satellite. After a brief historical introduction, we present a model of
supersymmetric inflation in which the CHDM model is neatly realized with a
spectral index n= 0.98, while the dark matter consists of a few eV `tau'
neutrino and the LSP (essentially the `bino'). We also provide a comparison of
this model against the observations.


title:
Recursive Algorithm for the Generation of Relativistic Kinematics for
  Collisions and Decays with Regularizations of Sharp Peaks

abstract:
  We describe an algorithm for the generation of relativistic kinematics for
collision and decay processes with multiparticle final states. In the framework
of this algorithm it is possible to generate different kinematics covering most
of practically interesting cases. One gets a possibility to introduce different
sets of integration variables. As a result different sets of kinematical
singularities can be regularized. To smooth sharp peaks some regularization
formulas and procedures are used covering most typical cases. The algorithm is
realized in the package CompHEP created for automatic calculations of collision
and decay processes.


title: Rare B -> K^* l^+ l^- Decay in Light Cone QCD

abstract:
  We investigate the transition formfactors for the B -> K^* l^+ l^- (l = mu,
tau) decay in the light cone QCD. It is found that the light cone and 3-point
QCD sum rules analyses for some of the formfactors for the decay B -> K^* l^+
l^- lead to absolutely different $q^2$ dependence. The invariant dilepton mass
distributions for the B -> K^* mu^+ mu^- and B -> K^* tau^+ tau^- decays and
final lepton longitudinal polarization asymmetry, which includes both short and
long-distance contributions, are also calculated.


title:
Signatures of Pseudo-Goldstone Bosons in Technicolor Theories with the
  GIM Mechanism

abstract:
  Technicolor models with the GIM mechanism are successful solutions to common
problems of technicolor model building. These models have a rich set of new
particles and interactions. We present the spectrum of the lightest exotic
particles in such models and their signatures in present and future collider
experiments.


title: Large N expansion in global and local supersymmetric theories

abstract:
  A systematic study of large N expansion in supersymmetric theories are given.
Supersymmetric O(N) non-linear sigma model in two and three dimensions,
massless and massive supersymmetric QCD with $N_{f}<N_{c}-1$ and supergravity
models are analyzed in detail. Our main motivation is to discuss how the
previously studied mechanism for dynamical generation of gaugino condensation
and superpotential is realized in the framework of large N expansion.


title:
$O(m_c^{-2})$ nonperturbative corrections to the inclusive rate of the
  decay $B \to X_s \gamma$

abstract:
  It is shown that the inclusive rate of the rare weak radiative decays $B \to
X_s \gamma$ contains a series of nonperturbative corrections, whose `short
distance' scale is set by $m_c^{-1}$, rather than by $m_b^{- 1}$. The first
correction in this series is expressed through the chromomagnetic interaction
of the $b$ quark inside the $B$ meson and the relative magnitude of the effect
is determined by the ratio $< {\overline B} | \bar b \sigma \cdot G b | B > /
m_c^2$. Though the magnitude of this first correction is suppressed by a
numerical coefficient, the sensitivity of the decay rate to the distance scale
$m_c^{-1}$ may significantly limit the accuracy of purely perturbative
predictions for the rate.


title: Broken Supersymmetric U(1) Gauge Factor at the TeV Scale

abstract:
  The appearance of a broken supersymmetric U(1) gauge factor at the TeV scale
is relevant for several reasons. If it truly exists, then one important
consequence is that at the 100 GeV energy scale, the two-doublet Higgs
structure is of a more general form than that of the Minimal Supersymmetric
Standard Model (MSSM). This is a prime example of tree-level nondecoupling.
Furthermore, a particular U(1)_N from the superstring-inspired E_6 model allows
for the existence of naturally light singlet neutrinos which may be necessary
to accommodate the totality of neutrino-oscillation experiments.


title: $B \to X_s \mu^+ \mu^-$ in Technicolor with Scalars

abstract:
  We compute the flavor changing neutral current process $B \to X_s \mu^+
\mu^-$ in technicolor models with scalars. We find that the branching ratio can
be enhanced relative to that of the Standard Model by as much as 60%. The full
parameter space of the model is consistent with the present CLEO and CDF
exclusive limits. However, the viability of the model could soon be tested
since the decay signals are expected to be observed in the next few years with
the upgraded CLEO detector and in the CDF Run II.


title:
Chiral expansion in the dual (string) models of the Goldstone meson
  scattering

abstract:
  We consider in details the dual models for the Goldstone mesons (pions)
scattering in the presence of the explicit chiral symmetry breaking caused by
non-zero current quark mass. New method of incorporation of the quark masses
into the dual model is suggested. In contrast to the previously considered in
the literature methods, the dual amplitude obtained by this method is
consistent with all low-energy theorems following from the Effective Chiral
Lagrangian (EChL) to the O(p^4) order and simultaneously it does not contain
states with negative width. The resonance spectrum of the model and its
implications for the fourth and sixth order EChL in large N_c limit are
discussed. We argue that the possible relations between large N_c QCD and some
underlying string theory can be revealed by studying interactions of hadrons at
low-energies.


title: Defect Formation in First Order Phase Transitions with Damping

abstract:
  Within the context of first order phase transitions in the early universe, we
study the influence of a coupling between the (global U(1)) scalar driving the
transition and the rest of the matter content of the theory. The effect of the
coupling on the scalar is simulated by introducing a damping term in its
equations of motion, as suggested by recent results in the electroweak phase
transition. After a preceeding paper, in which we studied the influence that
this coupling has in the dynamics of bubble collisions and topological defect
formation, we proceed in this paper to quantify the impact of this new effects
on the probability of defect creation per nucleating bubble.


title: The phenomenology of neutral heavy leptons

abstract:
  Naturally small neutrino masses can arise in some grand unified models. The
mechanism of neutrino mass generation in these models typically requires the
existence of neutral heavy leptons. We study the low-energy phenomenology of
these new fermions. Concentrating on loop corrections due to neutral heavy
leptons, we examine how the flavour-conserving leptonic decays of the Z boson,
universality breaking in these decays, and the W boson mass depend on the mass
and mixings of the neutral heavy leptons. Working within the framework of a
superstring-inspired SU(2)_L x U(1)_Y model, we show that these
flavour-conserving processes have some virtues over the traditionally
considered flavour-violating decays.


title: Practical techniques of QCD vs exact results of solvable models

abstract:
  We check quantitatively the validity of some popular phenomenological
approaches of QCD in simple models. Dispersion sum rules are considered within
the ladder approximation of a field-theoretic model with OPE given by ordinary
loop diagrams which are computable for any number of loops. A correlator of two
currents within the model complies with all requirements of standard QCD sum
rules approach for fitting low-lying resonances such as fast convergence and
good stability while the exact spectrum contains no resonance. Optimized PT as
it is inspired by the principle of minimal sensitivity is analyzed within a
quantum mechanical model and is shown to work well as compared to pure
asymptotic expansion in the coupling constant or Pad\'e approximation.
Renormalon technique is tested within another quantum mechanical model and is
found to fail to detect its low-energy structure.


title: A More Minimal Messenger Model of Gauge-Mediated Supersymmetry Breaking?

abstract:
  This Letter addresses a provocative question: ``Can the standard electroweak
Higgs doublets and their color-triplet partners be the messengers of a low
energy gauge-mediated SUSY breaking?" Such a possibility does not seem to be
immediately ruled out. If so, it can lead to a very economical scheme with
clear-cut predictions quite distinct from those of the conventional
gauge-mediated scenario. Namely, we get (i) a single light Higgs below the
original SUSY- breaking scale; (ii) tan(beta) = 1; (iii) flavor non-universal,
but automatically flavor-conserving soft scalar masses; (iv) a light colored
scalar with peculiar phenomenology. The familiar mu problem looses its meaning
in this approach.


title: Hadronic Decays of B Mesons

abstract:
  We review recent experimental results on hadronic decays and lifetimes of
hadrons containing b and c quarks. We discuss charm counting and the
semileptonic branching fraction in B decays, the color suppressed amplitude in
B decay, and the search for gluonic penguins in B decay.


title: Thermalization of a Quark-Gluon Plasma

abstract:
  The thermalization time for a Quark-Gluon-Plasma is estimated from a quantum
transport model beyond the quasi-particle approach (or kinetic gas theory).
While our ansatz is crude concerning the properties of ''real'' quarks and
gluons, it nevertheless takes very serious the basic principles of quantum
field theory for non-equilibrium states. It is found, that the thermalization
time obtained from quantum transport theory is substantially longer than from
kinetic theory. In our view this casts some doubts on scenarios which a priori
assume a thermalized quark gluon plasma.


title:
Predictions of $m_b/m_{\tau}$ and $m_t$ in an Asymptotically Non-Free
  Theory

abstract:
  We discuss an extention of the Minimal Supersymmetric Standard Model (MSSM)
with the 4th and anti-4th generations which have $SU(2)_L\times U(1)_Y$
invariant masses. Due to the the extra generations, all three running gauge
couplings become asymptotically non--free while preserving gauge coupling
unification at the GUT scale. We show that due to the asymptotically non--free
  character of the gauge couplings: (1) the top and bottom Yukawa couplings are
strongly focused onto infrared fixed points as they are evolved down in scale
making their values at $\mu=\mz$ insensitive to their initial values at
$\mu=\mgut$; (2) the model predicts $\R(\mz) \equiv Y_b/Y_\tau |_{\mu
=\mz}\approx 1.8$, which is consistent with the experimental value provided we
take the ratio of Yukawa couplings at the GUT scale to be $\R(\mgut) =
Y_b/Y_\tau |_{\mu = \mgut} = 1/3$; (3) the $t$ mass prediction comes out to be
$\mt\approx 180\,\GeV$ which is also consistent with experiment.


title: Magnetic Screening at Finite Temperature

abstract:
  It is shown that at finite temperature and in the presence of magnetic
sources magnetic fields are screened. This is proven within the framework of
classical transport theory both for the Abelian and non-Abelian plasmas.
Magnetic screening arises in this formalism as a consequence of polarization
effects occurring in the plasmas, and it is proportional to the inverse of the
gauge coupling constant. It is then discussed whether this mechanism could be
relevant in realistic quantum gauge field theories, such as QCD.


title: The Long Distance Contribution to $D\to\pi l^+l^-$

abstract:
  We calculate the long distance contribution to $D^{+,0}\to\pi^{+,0}l^+l^-$
decays by the use of a vector meson dominance model, in which the $\phi$-meson
plays the central role. The branching ratios obtained are $10^{-6}$ and a few
times $10^{-7}$ for the resonance and non-resonance regions respectively. The
analysis includes a calculation of $D^+\to\pi^+\phi$, consistent with the
experimental value.


title: Universality of the preasymptotics in the hadron and photon diffraction

abstract:
  We note that it is premature to make a conclusion on the multiplicity of the
Pomerons on the basis of the available experimental data since the interactions
have a preasymptotic nature


title: What is found upon defrosting the Universe after inflation

abstract:
  At the end of inflation the Universe is frozen in a near zero-entropy state
with energy density in a coherent scalar field and must be "defrosted" to
produce the observed entropy and baryon number. Baryon asymmetry may be
generated by the decay of supermassive Grand Unified Theory (GUT) bosons
produced non-thermally in a preheating phase after inflation, thus solving many
drawbacks facing GUT baryogenesis in the old reheating scenario.


title:
From Landau's Hydrodynamical Model to Field Theory Models of
  Multiparticle Production: A Tribute to Peter Carruthers on his 61st Birthday

abstract:
  We review the assumptions and domain of applicability of Landau's
Hydrodynamical Model. By considering two models of particle production, pair
production from strong electric fields and particle production in the linear
sigma model, we demonstrate that many of Landau's ideas are verified in
explicit field theory calculations.


title: Cold Dark Matter Detection via the LSP-Nucleus Elastic Scattering

abstract:
  The momentum transfer dependence of the LSP-nucleus elastic scattering cross
sections is studied. New imput SUSY parameters obtained in a phenomenologically
allowed parameter space are used to calculate the coherent rate for various
nuclear systems and the spin matrix elements for the proposed $^{207}Pb$
target. The results are compared to those obtained from other cold dark matter
detection targets.


title:
Cold Dark Matter in SUSY Theories. The Role of Nuclear Form Factors and
  the Folding with the LSP Velocity

abstract:
  The momentum transfer dependence of the total cross section for elastic
scattering of cold dark matter candidates, i.e. lightest supersymmetric
particle (LSP), with nuclei is examined. The presented calculations of the
event rates refer to a number of representative nuclear targets throughout the
periodic table and have been obtained in a relatively wide phenomenologically
allowed SUSY parameter space. For the coherent cross sections it is shown that,
since the momentum transfer can be quite big for large mass of the LSP and
heavy nuclei even though the energy transfer is small ($\le 100 KeV$), the
total cross section can in such instances be reduced by a factor of about five.
For the spin induced cross section of odd-A nuclear targets, as is the case of
$^{207}Pb$ studied in this work, we found that the reduction is less
pronounced, since the high multipoles tend to enhance the cross section as the
momentum transfer increases (for LSP $mass < 200 GeV$) and partially cancell
the momentum retardation. The effect of the Earth's revolution around the sun
on these event rates is also studied by folding with a Maxwellian LSP-velocity
distribution which is consistent with its density in the halos. We thus found
that the convoluted event rates do not appreciably change compared to those
obtained with an average velocity. The event rates increase with A and, in the
SUSY parameter space considered, they can reach values up to 140
$y^{-1}Kg^{-1}$ for Pb. The modulation effect, however, was found to be small
(less than $\pm 5%$).


title: LSP-Nucleus Elastic Scattering Cross Sections

abstract:
  We calculate LSP-nucleus elastic scattering cross sections using some
representative input in the restricted SUSY parameter space. The coherent
matrix elements are computed throughout the periodic table while the spin
matrix elements for the proposed $^{207}Pb$ target which has a rather simple
nuclear structure. The results are compared to those given from other cold dark
matter detection targets.


title: A New Approach of J/psi suppression in pA and AA Collisions

abstract:
  When the cross section of J/psi production is considered varying with the
energy of the nucleon-nucleon interaction the production of J/psi in pA and AA
collisions has been studied using FRITIOF Model. The calculation shows that the
cross section of J/psi production "per nucleon-nucleon collision" decreases
with increasing mass number and centrality as a consequence of continuous
energy loss of the projectile nucleons to the target nucleons in their
successive binary nucleon-nucleon collisions . We have compared our model
predictions with the experimental data of J/psi production.


title: Color-octet mechanism and J/psi polarization at LEP

abstract:
  Polarized heavy quarkonium productions in $Z^0$ decays are considered. We
find that polarizations of the produced quarkonia are independent of that of
the parent Z^0 provided that one considers the energy distribution or the total
production rate. Produced J/psi's via the color-octet and the color- singlet
mechanisms are expected to be 19% and 29% longitudinally polarized,
respectively. The energy dependence of eta_{1,8}(x)=\frac{dGamma_{1,8}^L}{dx}
/\frac{dGamma_{1,8}}{d x} is very sensitive to the production mechanism, and
therefore the measurement of \eta(x)_exp will be an independent probe of the
color-octet mechanism.


title:
Deep inelastic scattering of leptons from nuclear targets and the BFKL
  pomeron

abstract:
  We calculate shadowing in the process of deep inelastic interactions of
leptons with nuclei in the perturbative regime of QCD. We find appreciable
shadowing for heavy nuclei (e.g. Pb) in the region of small Bjorken scaling
variable $10^{-5}\leq x \leq 10^{-3}$. This shadowing depends weakly on $Q^2$,
but it may be strongly influenced, especially at $x \geq 10^{-3}$, by the
existence of real parts of the forward scattering amplitudes.


title: J/psi Production at the LHC

abstract:
  We firstly re-examine hadroproduction of prompt J/psi's at the Fermilab
Tevatron finding that those colour-octet matrix elements presented in
literature are systematically overestimated due to the overlooking of the
effective primordial transverse momentum of partons (i.e. dynamically generated
via initial-state radiation). We estimate the size of these effects using
different parton distribution functions in a Monte Carlo framework. Finally, we
extrapolate up to LHC energies making a prediction on the expected pt
differential cross-section for charmonium.


title: Heavy neutrinos detection in the Next Linear Collider

abstract:
  The possibility of detecting heavy neutrinos (M_N>M_Z) in the NLC is
examined.


title:
Infinite Momentum Frame Calculation of Semileptonic Heavy
  \Lambda_b\to\Lambda_c Transitions Including HQET Improvements

abstract:
  We calculate the transition form factors that occur in heavy $\Lambda$-type
baryon semileptonic decays as e.g. in $\Lambda_{b} \to \Lambda_{c}^{+} + l^{-}
+ \bar{\nu}_{l} $. We use Bauer-Stech-Wirbel type infinite momentum frame wave
functions for the heavy $\Lambda$-type baryons which we assume to consist of a
heavy quark and a light spin-isospin zero diquark system. The form factors at $
q^{2} = 0 $ are calculated from the overlap integrals of the initial and final
$\Lambda$-type baryon states. To leading order in the heavy mass scale the
structure of the form factors agrees with the HQET predictions including the
normalization at zero recoil. The leading order $\omega$-dependence of the form
factors is extracted by scaling arguments. By comparing the model form factors
with the HQET predictions at ${\cal O}(1/m_{Q})$ we obtain a consistent set of
model form factors up to ${\cal O}(1/m_{Q})$. With our preferred choice of
parameter values we find that the contribution of the non-leading form factor
is practically negligible. We use our form factor predictions to compute rates,
spectra and various asymmetry parameters for the semi-leptonic decay
$\Lambda_{b} \to \Lambda_{c}^{+} + l^{-} + \bar{\nu}_{l} $.


title:
Measuring anomalous ``spin'' in elastic e-p or \nu-p and deep inelastic
  e-p scattering

abstract:
  We obtain a general rule that the O(1/log m_h) term due to the current
\bar{h}\gamma_\mu\gamma_5h of a mass-m_h quark h in f-flavour theory is
-3\bar{g}^2_f(m_h)/{2\pi^2(33-2f)} times the flavour singlet current of the
residual (f-1)-flavour theory, where \bar{g}_f is the f-flavour running
coupling constant in a mass-independent renormalization scheme. The rule is
applied to the Ellis-Jaffe moment below and well above charm threshold, and to
low-energy Z^0-exchange amplitudes. The singlet axial charge of the proton
common to these experiments is both scale and gauge invariant, but is related
to the axial anomaly and the ``gluon spin'' by a non-perturbative
renormalization factor.


title: Macroscopic Parity Violation and Supernova Asymmetries

abstract:
  Core collapse supernovae are dominated by weakly interacting neutrinos. This
provides a unique opportunity for macroscopic parity violation. We speculate
that parity violation in a strong magnetic field can lead to an asymmetry in
the explosion and a recoil of the newly formed neutron star. We estimate the
asymmetry from neutrino-polarized-neutron elastic scattering, polarized
electron capture and neutrino-nucleus elastic scattering in a (partially)
polarized electron gas.


title: Probing Polarized Parton Distributions with Meson Photoproduction

abstract:
  Polarization asymmetries in photoproduction of high transverse momentum
mesons are a flavor sensitive way to measure the polarized quark distributions.
We calculate the expected asymmetries in several models, and find that the
asymmetries are significant and also significantly different from model to
model. Suitable data may come as a by-product of deep inelastic experiments to
measure $g_1$ or from dedicated experiments.


title: Can Neutrinos be Majorana Particles

abstract:
  It was recently claimed that the observed physical neutrinos cannot be of
Majorana type because such particles lack vector interactions. Contrary to this
claim we show that if the Majorana neutrino is massless it is indistinguishable
from the Dirac neutrino so that observed physical neutrinos may equally well be
of Majorana or Dirac type.


title: Cosmology of Radiatively Generated Axion Scale

abstract:
  We discuss some cosmological aspects of supersymmetric axion models in which
the axion scale is radiatively generated in terms of the weak scale and the
Planck scale. They include thermal inflation, axions produced by the decay of
oscillating Peccei-Quinn flatons, late time baryogenesis, and finally the
possibility to raise up the cosmological upper bound on the axion scale in
thermal inflation scenario.


title: Exclusive nonleptonic decays of B mesons

abstract:
  The energetic exclusive two-body nonleptonic decays of B mesons are
investigated in the framework of the relativistic quark model within the
factorization approximation. The heavy quark expansion is used for the
calculation of form factors. The obtained results are in agrement with
available experimental data.


title: Light Higgsino Dark Matter

abstract:
  We re-investigate the question whether a light higgsino-like neutralino is a
viable Dark Matter candidate. To this end we compute the dominant one-loop
corrections to the masses of the higgsino-like states in the minimal
Supersymmetric Standard Model (MSSM), due to loops involving heavy quarks and
their superpartners. We also calculate analogous corrections to the couplings
of higgsino-like neutralinos to Z and Higgs bosons. In the region of parameter
space leading to high higgsino purity of the lightest neutralino, these
corrections can change the expected relic density by up to a factor of five in
either direction. We conclude that for favorable choices of soft supersymmetry
breaking parameters, a state with more than 99% higgsino purity could indeed
form all cold Dark Matter in the Universe. In some cases these corrections can
also increase the expected cross section for LSP scattering off spinless nuclei
by up to two orders of magnitude, or reduce it to zero.


title:
Nonfactorizable Contributions to Hadronic Matrix Elelments by Use of
  Twist Wave Functions

abstract:
  A general approach for evaluating the nonfactorizable contributions to the
hadronic matrix elements is described in terms of the higher twist wave
functions of the mesons. An example is illustrated for the $B^{0} \to
\pi^{+}\pi^{-}$ decays.


title: A new type of spontaneous CP breaking

abstract:
  I present a new form of spontaneous CP violation in which, in analogy with
the left-right-symmetric model, CP breaking results from the inequality of two
real vacuum expectation values. In my model there is no scalar-pseudoscalar
mixing, and the smallness of strong CP violation finds a natural explanation.


title: A Glueball- $q\bar{q}$ Filter in Central Hadron Production

abstract:
  We have stumbled upon a remarkable empirical feature of central meson
production which separates established $q\bar{q}$ mesons from glueball
candidates. This does not appear to have been noted previously and we have no
simple explanation for it. We suggest that glueballs and $q\bar{q}$ of the same
$J^{PC}$ are distinguishable due to their boson versus fermion internal
structure and that this leads to a different topology for central production of
glueballs and $q\bar{q}$. Upon application of this test to data from the WA102
experiment we find that the $f_0(1500)$ and the $f_{2}(1900)$ show behaviour
consistent with glueballs and opposite to that exhibited by established
$q\bar{q}$ states.


title:
Description of hot compressed hadronic matter based on an effective
  chiral lagrangian

abstract:
  A review of the recent results obtained in the Nambu -- Jona-Lasinio model is
given. In particular, the effect of screening of meson fields at finite
temperature or density is analyzed and the formulation of a chirally invariant
transport theory for quark matter is presented.


title: Combined B->X_s\psi and B-> X_s\eta_c decays as a test of factorization

abstract:
  We calculate the inclusive decays $B\to X_s\psi$ and $B\to X_s\eta_c$ using
factorization assumption. To investigate the bound state effect of the decaying
B meson in these inclusive decays we take into account the motion of the $b$
quark using a Gaussian momentum distribution model. The resulting correction to
free quark decay approximation is around 6% at most. Utilizing a potential
model evaluation of the ratio of the decay constants $f^2_{\eta_c}/f^2_\psi$,
it is shown that the ratio $R=\Gamma (B\to X_s\eta_c )/\Gamma (B\to X_s\psi )$
can be used as a possible test of factorization assumption.


title: Charm Physics 1996 - A Retrospective

abstract:
  A pedagogically oriented review is given of progress made over the past year
in our understanding of physics related to the charm quark. Included are
discussions of the R_c deficit, the \psi' anomaly, charm spectroscopy, D
nonleptonic decays, searches for flavor-changing neutral currents, new limits
on D^0 - {\bar D}^0 mixing and prospects for future experimental studies of the
charm sector.


title:
VNI-3.1: MC-simulation program to study high-energy particle collisions
  in QCD by space-time evolution of parton-cascades and parton-hadron
  conversion

abstract:
  VNI is a general-purpose Monte-Carlo event-generator, which includes the
simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron,
hadron-nucleus, and nucleus-nucleus collisions. On the basis of
renormalization-group improved parton description and quantum-kinetic theory,
it uses the real-time evolution of parton cascades in conjunction with a
self-consistent hadronization scheme that is governed by the dynamics itself.
The causal evolution from a specific initial state (determined by the colliding
beam particles) is followed by the time-development of the phase-space
densities of partons, pre-hadronic parton clusters, and final-state hadrons, in
position-space, momentum-space and color-space. The parton-evolution is
described in terms of a space-time generalization of the familiar
momentum-space description of multipl (semi) hard interactions in QCD,
involving 2 -> 2 parton collisions, 2 -> 1 parton fusion processes, and 1 -> 2
radiation processes. The formation of color-singlet pre-hadronic clusters and
their decays into hadrons, on the other hand, is treated by using a spatial
criterion motivated by confinement and a non-perturbative model for
hadronization. This article gives a brief review of the physics underlying VNI,
which is followed by a detailed description of the program itself. The latter
program description emphasizes easy-to-use pragmatism and explains how to use
the program (including a simple example), annotates input and control
parameters, and discusses output data provided by it.


title:
Study Medium-induced Parton Energy Loss in Gamma+jet Events of
  High-Energy Heavy-Ion Collisions

abstract:
  The effect of medium-induced parton energy loss on jet fragmentation is
studied in high-energy heavy-ion collisions. It is shown that an effective jet
fragmentation function can be extracted from the inclusive $p_T$ spectrum of
charged particles in the opposite direction of a tagged direct photon with a
fixed transverse energy. We study the modification of the effective jet
fragmentation function due to parton energy loss in AA as compared to pp
collisions, including $E_T$ smearing from initial state radiations for the
photon-tagged jets. The effective fragmentation function at
$z=p_T/E_T^\gamma\sim 1$ in pA collisions is shown to be sensitive to the
additional $E_T$ smearing due to initial multiple parton scatterings whose
effect must be subtracted out in AA collisions in order to extract the
effective parton energy loss. Jet quenching in deeply inelastic lepton-nucleus
scatterings as a measure of the parton energy loss in cold nuclear matter is
also discussed. We also comment on the experimental feasibilities of the
proposed study at the RHIC and LHC energies and some alternative measurements
such as using $Z^0$ as a tag at the LHC energy.


title: Electroweak Interactions: Loops for Cyclists

abstract:
  We review the ideas of renormalizable field theories and the Standard Model
at the Born (neutral currents, the Higgs mechanism and unification) and quantum
level. We subsequently illustrate how high statistics experiments are producing
the first evidence for the validity of the Standard Model as a spontaneously
broken gauge theory.


title:
Quantum structure of the non-Abelian Weizsacker-Williams field for a
  very large nucleus

abstract:
  We consider the McLerran-Venugopalan model for calculation of the small-$x$
part of the gluon distribution function for a very large ultrarelativistic
nucleus at weak coupling. We construct the Feynman diagrams which correspond to
the classical Weizs\"{a}cker-Williams field found previously [Yu. V. Kovchegov,
Phys. Rev. D 54, 5463 (1996)] as a solution of the classical equations of
motion for the gluon field in the light-cone gauge. Analyzing these diagrams we
obtain a limit for the McLerran-Venugopalan model. We show that as long as this
limit is not violated a classical field can be used for calculation of
scattering amplitudes.


title: Chirality and Reliability of Baryon QCD Sum Rules

abstract:
  The QCD sum-rule method has been widely used in studying various baryon
properties. For a given problem, there are usually more than one sum rules and
they do not work equally well. In this paper, we point out that chirality plays
an important role in determining the reliability of a baryon sum rule. The
contributions of positive- and negative-parity excited baryon states partially
cancel each other in the chiral-odd sum rules, but add up in the chiral-even
sum rules. As such, the chiral-odd sum rules are generally more reliable than
the chiral-even sum rules. This allows one to identify the more reliable sum
rules and use them in extracting the ground-state baryon property of interest.
This is illustrated in an explicit example.


title: CP Violation Beyond the Standard Model

abstract:
  We review CP violation in various extensions of the electroweak sector of the
Standard Model. A particular emphasis is put on supersymmetric models. We
describe the two CP problems of supersymmetry, concerning $d_N$ and
$\epsilon_K$. We critically review the various mechanisms that have been
suggested to solve these problems: exact universality, approximate CP symmetry,
alignment, approximate universality and heavy squarks. We explain how future
measurements of CP violation will test these mechanisms. We describe extensions
of the quark sector and their implications on CP asymmetries in neutral B
decays, on the $K_L \to \pi \nu \bar\nu$ decay and on $\Delta\Gamma(B_s)$. We
discuss CP violation in charged scalar exchange in models with natural flavor
conservation and explain how transverse lepton polarization in meson decays can
probe such models. CP violation in neutral scalar exchange arises in models of
horizontal symmetries and may be manifest in heavy quark (b and t) physics. We
describe the implications of Left-Right Symmetric models on $d_N$,
$\epsilon_K$, $\epsilon'/\epsilon$ and CP asymmetries in B decays. Finally, we
briefly discuss the potential of future measurements of CP violation to
discover New Physics.


title: A natural solution to the $\mu$-problem in dynamical supergravity model

abstract:
  The Higgs mixing term coefficient $\mu$ is calculated in the supersymmetric
theory which possesses a non-anomalous $U(1)_{R}$ symmetry in the limit of
global supersymmetry. In this model, supersymmetry is assumed to be broken by
gaugino condensation in the hidden sector when the supergravity effects are
turned on. The soft breaking terms in the visible sector and the $\mu$ term of
order the weak scale are produced in a simple manner.


title:
Factorization theorems, effective field theory, and nonleptonic heavy
  meson decays

abstract:
  The nonleptonic heavy meson decays $B\to D^{(*)}\pi(\rho), J/\psi K^{(*)}$
and $D\to K^{(*)}\pi$ are studied based on the three-scale perturbative QCD
factorization theorem developed recently. In this formalism the
Bauer-Stech-Wirbel parameters a_1 and a_2 are treated as the Wilson
coefficients, whose evolution from the W boson mass down to the characteristic
scale of the decay processes is determined by effective field theory. The
evolution from the characteristic scale to a lower hadronic scale is formulated
by the Sudakov resummation. The scale-setting ambiguity, which exists in the
conventional approach to nonleptonic heavy meson decays, is moderated.
Nonfactorizable and nonspectator contributions are taken into account as part
of the hard decay subamplitudes. Our formalism is applicable to both bottom and
charm decays, and predictions, including those for the ratios R and R_L
associated with the $B\to J/\psi K^{(*)}$ decays, are consistent with
experimental data.


title:
Remarks on the Strong Coupling Constants in Heavy Hadron Chiral
  Lagrangians

abstract:
  In the heavy quark limit, there are three independent strong axial coupling
constants in chiral Lagrangians for ground-state heavy hadrons: g in the meson
sector, and g_1, g_2 in the baryon sector. The coupling g_2 is extracted from
recent CLEO measurements of $\Sigma_c^*\to\Lambda_c\pi$ to be $|g_2|=0.57\pm
0.10$, in agreement with the nonrelativistic quark model expectation but in
$2\sigma$ deviation from the large-N_c argument. The parameter g_1 cannot be
determined directly from strong decays of heavy baryons. Nevertheless, some
information of g_1 can be learned from the radiative decay
$\Xi_c^{'*0}\to\Xi_c^0\gamma$, which is prohibited at tree level by SU(3)
symmetry but induced by chiral loops. A measurement of
$\Gamma(\Xi_c^{'*0}\to\Xi_c^0\gamma)$ will yield two possible solutions for
g_1. Assuming the validity of the quark model relations among different
coupling constants, the experimental value of g_2 implies that $|g|=0.70\pm
0.12$ and $|g_1|=0.93\pm 0.16$.


title:
Color-octet mechanism in the inclusive D-wave charmonium productions in
  B decays

abstract:
  The inclusive D-wave charmonium production rates in B decays are considered
in the Bodwin-Braaten-Lepage (BBL) approach. We find that the color-octet
subprocesses B->cc_(^3S_1^(8) or ^3P_J^(8))+s,d, followed by the transition
cc_(^3S_1^(8) or ^3P_J^(8)) -> ^3D_J, strongly dominate over any other
subprocess, due to the large Wilson coefficient for the \Delta B = 1 effective
lagrangian. Assuming that the numerical values of the matrix elements
<0|O^{^3D_J}(^3S_1^(8))|0> and <0|O^{^3D_J}(^3P_J^(8))|0> are the same order of
magnitudes with the <0| O^{\psi^'}(^3S_1^(8))|0>, we find that the ^{1,3}D_{2}
can be observed at future B-factories.


title:
Behaviour of the forward peak in hard diffractive leptoproduction of
  vector mesons

abstract:
  The measured forward slope in elastic and inelastic leptoproduction of vector
mesons differ by a substantial amount. In an attempt to describe this
phenomenon we construct a two radii model for the target proton, and estimate
the effective parameters of the hard Pomeron obtained from a pQCD dipole model
with eikonal shadowing corrections (SC). We show that the SC reduce the
intercept of the hard Pomeron and generate an effective shrinkage of the
forward peak and a diffractive dip at $|t| \approx 1 GeV^2$, which appears to
affect the value of the experimentally measured slope.


title:
In-Medium Chiral Perturbation Theory and Pion Weak Decay in the Presence
  of Background Matter

abstract:
  Two-point functions related to the pion weak decay constant f_\pi are
calculated from the generating functional of chiral perturbation theory in the
mean-field approximation and the heavy-baryon limit. The aim is to demonstrate
that Lorentz invariance is violated in the presence of background matter. This
fact manifests itself in the splitting of both f_\pi and the pion mass into
uncorrelated time- and spacelike parts. We emphasize the different in-medium
renormalizations of the correlation functions, show the inequivalence between
the in-medium values of f_\pi deduced from Walecka-type models, on the one
hand, and QCD sum rules, on the other hand, and elaborate on the importance for
some nuclear physics observables.


title:
Use and Misuse of QCD Sum Rules in Heavy-to-light Transitions: the Decay
  $B\to\rho e \nu$ Reexamined

abstract:
  The existing calculations of the form factors describing the decay $B\to\rho
e \nu$ from QCD sum rules have yielded conflicting results at small values of
the invariant mass squared of the lepton pair. We demonstrate that the
disagreement originates from the failure of the short-distance expansion to
describe the $\rho$ meson distribution amplitude in the region where almost the
whole momentum is carried by one of the constituents. This limits the
applicability of QCD sum rules based on the short-distance expansion of a
three-point correlation function to heavy-to-light transitions and calls for an
expansion around the light-cone, as realized in the light-cone sum rule
approach. We derive and update light-cone sum rules for all the semileptonic
form factors, using recent results on the $\rho$ meson distribution amplitudes.
The results are presented in detail together with a careful analysis of the
uncertainties, including estimates of higher-twist effects, and compared to
lattice calculations and recent CLEO measurements. We also derive a set of
``improved'' three-point sum rules, in which some of the problems of the
short-distance expansion are avoided and whose results agree to good accuracy
with those from light-cone sum rules.


title:
Production of Meson Pairs Involving $L \neq 0$ Mesons in Photon-Photon
  Collisions

abstract:
  We present a formalism for studying the exclusive production or decay of
mesons with any value of the internal orbital angular momentum L. As an
application, we discuss the production of meson pairs (involving tensor and
pseudotensor mesons) in photon-photon collisions.


title: Non-Abelian String Conductivity

abstract:
  We examine current-carrying configurations of cosmic strings in non-Abelian
gauge theories. We study the solutions numerically and point out that the
currents will be at best dynamically stable and not subject to any topological
quantisation or conservation, as in conventional models of string
superconduction. We suggest that non-Abelian string loops may be unable to
support persistent currents in the absence of external fields. This will have
relevance to vorton stability.


title:
A Complete Leading-Order, Renormalization-Scheme-Consistent Calculation
  of Small--x Structure functions, Including Leading-ln(1/x) Terms

abstract:
  We present calculations of the structure functions F_2(x,Q^2) and F_L(x,Q^2),
concentrating on small x. After discussing the standard expansion of the
structure functions in powers of \alpha_s(Q^2) we consider a leading-order
expansion in ln(1/x) and finally an expansion which is leading order in both
ln(1/x) and \alpha_s(Q^2), and which we argue is the only really correct
expansion scheme. Ordering the calculation in a renormalization-scheme-
consistent manner, there is no factorization scheme dependence, as there should
not be in calculations of physical quantities. The calculational method
naturally leads to the ``physical anomalous dimensions'' of Catani, but imposes
stronger constraints than just the use of these effective anomalous dimensions.
In particular, a relationship between the small-x forms of the inputs
F_2(x,Q_0^2) and F_L(x,Q_0^2) is predicted. Analysis of a wide range of data
for F_2(x,Q^2) is performed, and a very good global fit obtained, particularly
for data at small x. The fit allows a prediction for F_L(x,Q^2) to be produced,
which is smaller than those produced by the usual NLO-in-\alpha_s(Q^2) fits to
F_2(x,Q^2) and different in shape.


title:
Calculation of P-Wave Charmonium Decay Rates Using Dimensional
  Regularization

abstract:
  Contributions to the decay rates of P-wave charmonium states that are
proportional to $n_f \alpha_s^3$, where $n_f$ is the number of flavors of light
quarks, are calculated in the framework of nonrelativistic QCD using the
threshold expansion method. Dimensional regularization is used to regularize
the infrared divergences that arise from the emission of a soft gluon. Our
results are consistent with the original calculations of Barbieri et al.


title: Reparameterization Invariance Revisited

abstract:
  Reparameterization invariance, a symmetry of heavy quark effective theory,
appears in different forms in the literature. The most commonly cited forms of
the reparameterization transformation are shown to induce the same constraints
on operators that do not vanish under the equation of motion to order $1/m^2$,
and to be related by a redefinition of the heavy quark field. We give a new,
very straightforward proof that that the reparameterization invariance
constraints apply to all orders in $\alpha_s$ under matching to full QCD and
renormalization-group running, at least up to and including $O(1/m^2)$.


title: Cosmology of Supersymmetric Models with Low-energy Gauge Mediation

abstract:
  We study the cosmology of supersymmetric models in which the supersymmetry
breaking effects are mediated by gauge interactions at about the 10^5 GeV
scale. We first point out that the gravitino is likely to overclose the
Universe in this class of models. This requires an entropy production, which
prefers a baryogenesis mechanism at a relatively low temperature. The
Affleck-Dine mechanism for baryogenesis is one of the possibilities to generate
enough baryon asymmetry, but the analysis is non-trivial since the shape of the
potential for the flat direction differs substantially from the conventional
hidden sector case. To see this, we first perform a 2-loop calculation to
determine the shape of the potential. By combining the potential with the
supergravity contribution, we then find that the Affleck-Dine baryogenesis
works efficiently to generate sufficient baryon asymmetry. On the other hand,
we also point out that string moduli fields, if present, are stable and their
coherent oscillations overclose the Universe by more than 15 orders of
magnitude. One needs a very late inflationary period with an e-folding of N
\gtrsim 5 and an energy density of \lesssim (10^7 GeV)^4. A thermal inflation
is enough for this purpose. Fortunately, the Affleck-Dine baryogenesis is so
efficient that enough baryon asymmetry can survive the late inflation.


title: Probing the CP of the Higgs at an electron-electron Collider

abstract:
  The sensitivity of various angular and energy distributions to the CP of a
Higgs candidate are considered for the process $e^-e^- -> e^-e^-h$, where h is
either a scalar or a pseudoscalar Higgs. This process may differ from the
corresponding production at an $e^+e^-$ collider in the availability of both
beams being polarized. Beam polarization enhances the sensitivity of the
azimuthal distribution.


title: Can high energy cosmic rays be vortons ?

abstract:
  A simple model is exhibited in which the remnant density of charged vortons
is used to provide candidates for explaining the observed ultra high energy
cosmic rays (above $10^{20}$ eV). These vortons would be accelerated in active
galaxies and propagated through intergalactic medium with negligible losses of
energy. The expected number density of observable events is shown to be
consistent with extrapolation of the observations. The spectrum is predicted to
be spatially isotropic while its shape is that of an atomic
excitation-ionisation, i.e. with a few peaks followed by a continuum; there is
also an energy threshold below which no vorton is visible.


title: Jet Shapes in $ep$ and $p\overline{p}$ Collisions in NLO QCD

abstract:
  We have calculated jet shapes in low $Q^2$ $ep$ and $p\overline{p}$
collisions in perturbation theory at order $\alpha_s^3$ for the hard
parton-parton processes. For the $\gamma p$ process resolved and direct
contributions are superimposed. The dependence of the jet shapes on transverse
energy, rapidity, and inner cone extension is studied. The numerical results of
the calculation are compared with recent data from ZEUS at HERA and from CDF
and D0 at the TEVATRON. Good agreement is achieved if the problem of merging
overlapping jets is taken into account by varying the parameter $R_{sep}$ as a
function of transverse energy and rapidity.


title:
Chiral Quark Model of Nucleon Spin-Flavor Structure with SU(3) and
  Axial-U(1) Breakings

abstract:
  The chiral quark model with a nonet of Goldstone bosons can yield an adequate
description of the observed proton flavor and spin structure. In a previous
publication we have compared the results of a SU(3) symmetric calculation with
the phenomenological findings based on experimental measurements and SU(3)
symmetry relations. In this paper we discuss their SU(3) and axial-U(1)
breaking corrections. With two parameters, we obtain a very satisfactory fit to
the F/D ratios for the octet baryon masses and for their axial vector
couplings, as well as the different quark flavor contributions to the proton
spin. The result also can account for, not only the light u and d quark
asymmetry, but also the strange quark content, of the proton sea. SU(3)
breaking is the key in reconciling the strange quark fraction as measured in
the neutrino charm production and that as deduced from the pion nuleon sigma
term.


title: Gluon fragmentation to ^3D_J quarkonia

abstract:
  We present a calculation of the leading order QCD fragmentation functions for
gluons to split into spin-triplet D-wave quarkonia. We apply them to evaluate
the gluon fragmentation contributions to inclusive ^3D_J quarkonium production
at large transverse momentum processes like the Tevatron and find that the
D-wave quarkonia, especially the charmonium 2^{--} state, could be observed
through color-octet mechanism with present luminosity. Since there are
distinctively large gaps between the contributions of two different (i.e,
color-singlet and color-octet) quarkonium production mechanisms, our results
may stand as a unique test to NRQCD color-octet quarkonium production
mechanism.


title: D-wave charmonium production in B decays

abstract:
  The calculation of D-wave charmonium prodution rates in B meson deacys under
the NRQCD factorization formalism is presented. We find that inclusion of the
color-octet contributions permits us to detect the D-wave charmonium states in
B decays at present experimental facilities. The same amount signals of 2^{--}
D-wave state as that of \psi' could be observed at LEP and CESR. We also
predict the relative production rates for four D-wave states are
\delta^c:\delta^c_1: \delta^c_2:\delta^c_3=2.5:3:5:7, where \delta^c,
\delta^c_1, \delta^c_2, \delta^c_3 represent respectively the 2^{-+}, 1^{--},
2^{--}, 3^{--} states.


title: Neutrinoless Double Beta Decay with Composite Neutrinos

abstract:
  We study in detail the contribution of heavy composite Majorana neutrinos to
neutrino-less double beta decay. Our analysis confirms the result of a previous
estimate by two of the authors. Excited neutrinos couple to the electroweak
gauge bosons through a magnetic type effective Lagrangian.
  The relevant nuclear matrix element is related to matrix elements available
in the literature and current bounds on the half-life of neutrino-less double
beta decay are converted into bounds on the compositeness scale and/or the
heavy neutrino mass. Our bounds are of the same order of magnitude as those
available from accelerator experiments.