title:
CP-Violating Asymmetries in Charmless Non-Leptonic Decays $B \to PP, PV,
  VV$ in the Factorization Approach

abstract:
  We present estimates of the direct (in decay amplitudes) and indirect
(mixing- induced) CP-violating asymmetries in the non-leptonic charmless
two-body decay rates for $B \to PP$, $B \to PV$ and $B \to VV$ decays and their
charged conjugates, where P(V) is a light pseudoscalar (vector) meson. These
estimates are based on a generalized factorization approach making use of
next-to-leading order perturbative QCD contributions which generate the
required strong phases. No soft final state interactions are included. We study
the dependence of the asymmetries on a number of input parameters and show that
there are at least two (possibly three) classes of decays in which the
asymmetries are parametrically stable in this approach. The decay modes of
particular interest are: $\optbar{B^0} \to \pi^+ \pi^-$, $\optbar{B^0} \to
K_S^0 \pi^0$, $\optbar{B^0} \to K_S^0 \eta^\prime$, $\optbar{B^0} \to K_S^0
\eta$ and $\optbar{B^0} \to \rho^+ \rho^-$. Likewise, the CP-violating
asymmetry in the decays $\optbar{B^0} \to K_S^0 h^0$ with $h^0=\pi^0,K_S^0,
\eta,\eta^\prime$ is found to be parametrically stable and large. Measurements
of these asymmetries will lead to a determination of the phases $\sin 2\alpha$
and $\sin 2 \beta$ and we work out the relationships in these modes in the
present theoretical framework. We also show the extent of the so-called
"penguin pollution" in the rate asymmetry $A_{CP}(\pi^+ \pi^-)$ and of the
"tree shadow" in the asymmetry $A_{CP}(K_S^0\eta^\prime)$ which will effect the
determination of $\sin 2 \alpha$ and $\sin 2 \beta$ from the respective
measurements. CP-violating asymmetries in $B^\pm \to \pi^\pm \eta^\prime$,
$B^\pm \to K^{*\pm} \eta$, $B^\pm \to K^{*\pm} \eta^\prime$ and $B^\pm \to
K^{*\pm}\rho^0$ are potentially interesting and are studied here.


title:
Quark-Hadron Duality in the 't Hooft Model for Meson Weak Decays:
  Different Quark Diagram Topologies

abstract:
  We compare the effects of different quark diagram topologies on the weak
hadronic width of heavy-light mesons in the large N_c limit. We enumerate the
various topologies and show that the only one dominant (or even comparable) in
powers of N_c to the noninteracting spectator "tree" diagram is the
"annihilation" diagram, in which the valence quark-antiquark pair annihilate
weakly. We compute the amplitude for this diagram in the 't Hooft model (QCD in
1+1 spacetime dimensions with a large number of colors N_c) at the hadronic
level and compare to the Born term partonic level. We find that quark-hadron
duality is not well satisfied, even after the application of a smearing
procedure to the hadronic result. A number of interesting subtleties absent
from the tree diagram case arise in the annihilation diagram case, and are
described in detail.


title: Radiative Decay of a Long-Lived Particle and Big-Bang Nucleosynthesis

abstract:
  The effects of radiatively decaying, long-lived particles on big-bang
nucleosynthesis (BBN) are discussed. If high-energy photons are emitted after
BBN, they may change the abundances of the light elements through
photodissociation processes, which may result in a significant discrepancy
between the BBN theory and observation. We calculate the abundances of the
light elements, including the effects of photodissociation induced by a
radiatively decaying particle, but neglecting the hadronic branching ratio.
Using these calculated abundances, we derive a constraint on such particles by
comparing our theoretical results with observations. Taking into account the
recent controversies regarding the observations of the light-element
abundances, we derive constraints for various combinations of the measurements.
We also discuss several models which predict such radiatively decaying
particles, and we derive constraints on such models.


title:
Exclusive Processes at Intermediate Energy, Quark-Hadron Duality and the
  Transition to Perturbative QCD

abstract:
  Experiments at CEBAF will scan the intermediate-energy region of the QCD
dynamics for the nucleon form factors and for Compton Scattering. These
experiments will definitely clarify the role of resummed perturbation theory
and of quark-hadron duality (QCD sum rules) in this regime. With this
perspective in mind, we review the factorization theorem of perturbative QCD
for exclusive processes at intermediate energy scales, which embodies the
transverse degrees of freedom of a parton and the Sudakov resummation of the
corresponding large logarithms. We concentrate on the pion and proton
electromagnetic form factors and on pion Compton scattering. New ingredients,
such as the evolution of the pion wave function and the complete two-loop
expression of the Sudakov factor, are included. The sensitivity of our
predictions to the infrared cutoff for the Sudakov evolution is discussed. We
also elaborate on QCD sum rule methods for Compton Scattering, which provide an
alternative description of this process. We show that, by comparing the local
duality analysis to resummed perturbation theory, it is possible to describe
the transition of exclusive processes to perturbative QCD.


title:
Constraints on free parameters of the simplest bilepton gauge model from
  the neutral kaon system mass difference

abstract:
  We consider the contributions of the exotic quarks and gauge bosons to the
mass difference between the short- and the long-lived neutral kaon states in
$SU(3)_C \times SU(3)_L \times U(1)_N$ model. The lower bound $M_{Z'} \sim$ 14
TeV is obtained for the extra neutral gauge boson ${Z'}^0$. Ranges for values
of one of the exotic quark masses and quark mixing parameters are also
presented.


title:
CP violation in the annihilation $e^{+}~e^{-} \to t~\bar{t}$ within the
  Model-III of the two-Higgs-doublet extension

abstract:
  The CP-violating effects are studied in the electron-positron annihilation to
produce $t\bar{t}$ pair within the Model-III of the two-Higgs-doublet
extensions, which allows flavor changing neutral currents via Higgs exchanges.
Complete analytical expressions for the form factors of the top quark electric
and weak dipole moment induced in the framework of the model are presented.
Several observables sensitive to the CP violation are calculated. The
dependences of the CP-violating effects on Higgs boson masses and the possible
phase angles are discussed. We find that the CP-violating observables can be of
the order of $10^{-4}$ in general but may reach to $10^{-3}$ for the most
favorable parameters in the model.


title: Energy Loss in Nuclear Drell-Yan Process

abstract:
  By means of the nuclear parton distributions which can be used to provide a
good explanation for the EMC effect in the whole x range, we investigate the
energy loss effect in nuclear Drell-Yan process. When the cross section of
lepton pair production is considered varying with the center-of-mass energy of
the nucleon-nucleon collision, we find that the nuclear Drell-Yan(DY) ratio is
suppressed due to the energy loss, which balances the overestimate of the DY
ratio only in consideration of the effect of nuclear parton distributions.


title: Spin physics with spin-0 hadrons

abstract:
  We discuss various azimuthal asymmetries in semi-inclusive DIS and e^+e^- ==>
h1 h2 X which involve chiral odd quantities like the transversity distribution
h_1 and a fragmentation function H_1^\perp. For the fragmentation described by
H_1^\perp azimuthal angular dependence has to be measured, but no polarization
vector of a final state hadron. We present first results on asymmetries
including the electroweak currents in one-hadron inclusive DIS.


title: Neutrino masses and mixing

abstract:
  We present a short review of the present status of the problem of neutrino
masses and mixing. The existing experimental results indicate that there are at
least four massive neutrinos. We show that only two schemes with mixing of four
neutrinos and mass spectra in which two groups of close masses are separated by
the ``LSND gap'' (~ 1 eV) are compatible with the results of all neutrino
oscillation experiments. We discuss different consequences of these schemes for
future neutrino oscillation experiments.


title: Scalar Glueball Decay Into Pions In Effective Theory

abstract:
  We examine the mixing between the sigma meson $\sigma$ and the "pure"
glueball field $H$ and study the decays of the scalar glueball candidate
$f_0(1500)$ (a linear combination of $\sigma$ and $H$) into two and four pions
in effective linear sigma model. From recent experimental data on $f_0(1500)$
decay to pions we point out that the mixing angle is of order of 0.1.


title: The Jet Multiplicity as a Function of Thrust

abstract:
  We calculate the average multiplicity of jets in e+e- annihilation as a
function of both the jet resolution parameter, y_cut, and the thrust T. Our
result resums to all orders the leading and next-to-leading logarithms in y_cut
and 1-T, and is exact up to second order in alpha_s. This allows a comparison
between the number of jets found using jet algorithms and the ability to
distinguish different jet topologies via thrust.


title: Secondary Heavy Quark Pair Production in e+e- Annihilation

abstract:
  The multiplicity of heavy quarks from gluon splitting in e+e- annihilation
has now been theoretically calculated and experimentally measured at LEP.
However, the experimental measurement requires theoretical input for the shape
of the multiplicity with respect to an event shape. In this paper we calculate
the multiplicity of heavy quarks from gluon splitting in e+e- annihilation as a
function of the heavy jet mass of the event, to next-to-leading logarithmic
accuracy. We compare our result with Monte Carlo predictions.


title:
On the universality of the a priori mixing angles in weak radiative
  decays of hyperons

abstract:
  Strong-flavor and parity a priori mixing in hadrons are shown to describe
well the experimental evidence on weak radiative decays of hyperons. An
independent determination of the a priori mixing angles is performed. The
values obtained for them are seen to have a universality-like property, when
compared to their values in non-leptonic decays of hyperons.


title: SU(3) symmetry breaking in hyperon semileptonic decays

abstract:
  Flavor SU(3) symmetry breaking in the hyperon semileptonic decay form-factors
is analyzed using the 1/N expansion. A detailed comparison with experimental
data shows that corrections to f_1 are approximately 10%, which agrees with
theoretical expectations. Corrections to g_1 are compatible with first-order
symmetry breaking. A fit to the experimental data allows one to predict the g_1
form factor for Xi^0 -> Sigma^+ decay. The proton matrix element of the T^8
component of the axial current (which is equal to 3F-D in the SU(3) symmetry
limit) is found to be approximately 0.34.


title:
Getting the Supersymmetric Unification Scale from Quantum Confinement
  with Chiral Symmetry Breaking

abstract:
  Two models which generate the supersymmetric Grand Unification Scale from the
strong dynamics of an additional gauge group are presented. The particle
content is chosen such that this group confines with chiral symmetry breaking.
Fields that are usually introduced to break the Grand Unified group appear
instead as composite degrees of freedom and can acquire vacuum expectation
values due to the confining dynamics. The models implement known solutions to
the doublet-triplet splitting problem. The SO(10) model only requires one
higher dimensional representation, an adjoint. The dangerous coloured
Higgsino-mediated proton decay operator is naturally suppressed in this model
to a phenomenologically interesting level. Neither model requires the presence
of gauge singlets. Both models are only technically natural.


title: Deconfinement and Percolation

abstract:
  Using percolation theory, we derive a conceptual definition of deconfinement
in terms of cluster formation. The result is readily applicable to infinite
volume equilibrium matter as well as to finite size pre-equilibrium systems in
nuclear collisions.


title:
High Energy Neutrino, Photon and Cosmic Ray Fluxes from VHS Cosmic
  Strings

abstract:
  Decaying topological defects, in particular cosmic strings, can produce a
significant flux of high energy neutrinos, photons and cosmic rays. According
to the prevailing understanding of cosmic string dynamics in an expanding
Universe, the network of long strings loses its energy first into string loops,
which in turn give off most of their energy as gravitational radiation.
However, it has been suggested by Vincent et al. (VHS) that particle emission
may be the dominant energy loss channel for the long string network. In this
case, the predicted flux of high energy particles would be much larger. Here we
calculate the predicted flux of high energy gamma rays, neutrinos and cosmic
ray antiprotons and protons as a function of the scale of symmetry breaking at
which the strings are produced and as a function of the initial energy m_J of
the particle jets which result from the string decay. Assuming the validity of
the VHS scenario, we find that due to the interactions with the cosmic
radiation backgrounds all fluxes but the neutrino flux are suppressed at the
highest energies. This indicates that the observed events above the GZK cutoff
can only be accounted for in this scenario if the primary particle is a
neutrino and the scale of the symmetry breaking is somewhat less than the GUT
scale. The domain of parameter space corresponding to GUT-scale symmetry
breaking is excluded also by the current observations below the GZK cutoff. A
new aspect of this work is the calculation of the spectrum of the tau neutrinos
directly produced in the decay of the X-particles. This significantly increases
the tau neutrino signal at high energies in all cosmic string scenarios.


title:
Gap equation in finite-temperature three-dimensional QED beyond the
  bare-vertex approximation

abstract:
  Dynamical mass generation in a three-dimensional version of
finite-temperature QED is studied with the help of Schwinger-Dyson equations in
the real-time formalism. We go beyond the bare-vertex approximation and include
wave-function renormalization effects. This introduces a system of two integral
equations which are solved numerically. In order to increase the reliability of
the results, fermion and photon self-energies varying independently with energy
and momentum are used. The method applied enables a detailed study of the
behaviour of the theory with increasing temperature and number of fermion
flavours.


title:
Statistical model analysis of multiparticle correlations in e^+e^-
  annihilation

abstract:
  A new statistical model for multiparticle production in $e^+e^-$ annihilation
is proposed based on the idea of the longitudinal phase space with limited
transverse momentum. The longitudinal rapidity space is divided into cells of
equal size in order to take into account the Bose-Einstein correlations(BEC)
with a finite correlation length $\delta y$. The maximum entropy method is used
to determine the probability distributions of the final state pions (or $\rho$
mesons) for a given mean multiplicity, mean transverse momentum and mean total
energy. Event simulation based on our model is performed in two extreme cases,
a $\pi$-model and a $\rho$-model. The $\pi$-model assumes that only pions are
produced directly. On the other hand, the $\rho$-model assumes that only $\rho$
mesons are produced directly and they decay into pions. A good overall fit to
experimental data from PETRA to LEP energy regions is obtained for $\delta y$
ranging from 0.6 to 1.2 in the $\pi$-model. We found that the BEC plays a very
important role to reproduce various correlation data. In some correlation data,
resonance effect and conservation laws are also important.


title: Exclusive Semileptonic and Rare B-Meson Decays in QCD

abstract:
  We present the first complete results for the semileptonic and rare radiative
form factors of B-mesons weak decay into a light vector-meson (rho, omega, K*,
phi) in the light-cone sum-rule approach. The calculation includes radiative
corrections, higher-twist corrections and SU(3)-breaking effects. The
theoretical uncertainty is investigated in detail. A simple parametrization of
the form factors is given in terms of three parameters each. We find that the
form factors observe several relations inspired by heavy-quark symmetry.


title:
Exclusive semileptonic decays of B mesons to orbitally excited D mesons
  in the relativistic quark model

abstract:
  Exclusive semileptonic B meson decays to orbitally excited D mesons are
investigated in the infinitely heavy quark limit in the framework of the
relativistic quark model based on the quasipotential approach. The B\to
D^{**}e\nu Isgur-Wise functions \tau_{3/2}(w) and \tau_{1/2}(w) are determined.
It is found that the relativistic transformation of the meson wave functions
(Wigner rotation of the light quark spin) contribute already at the leading
order of the heavy quark expansion.


title: Potential NRQED: The Positronium Case

abstract:
  We discuss in detail potential NRQED (pNRQED), a previously proposed
effective field theory for ultrasoft photons. The pNRQED lagrangian for the
equal mass case is presented and it is shown that it correctly reproduces the
positronium spectrum at order $m\alpha^5$. The pNRQED lagrangian for the
unequal mass case is also presented at the same order. Dimensional
regularization is used throughout.


title: Improved Unitarity Bounds for B -> Pi Decays

abstract:
  We obtain model independent bounds for the form factors which arise in
semileptonic B -> Pi decays. To this end we derive a theoretical restriction
for possible combinations of the value of the form factor and its derivatives
at the endpoint region. These restrictions are then used as an input in a -
slightly modified - general formalism, which has already been deduced and
applied in earlier publications. Our results can be used to set constraints on
the form factors which have to be obeyed by all model dependent
parametrizations.


title: Z-Observables and the Effective Weak Mixing Angle in the MSSM

abstract:
  We make a comparison of the predicted effective weak mixing angle, the Z-on
resonance asymmetries and the W-boson mass to the LEP and SLD data at their
present status. We find that the predicted MSSM values for the effective weak
mixing angle are in agreement with the LEP+SLD average value for a ``heavy''
SUSY breaking scale while we observe an agreement with SLD data in the case of
a ``light'' SUSY breaking scale. The resulting values for the W-boson mass and
for the electron left-right asymmetries are compatible with CDF,UA2,DO and LEP
data respectively. Unexpectedly we find that the supersymmetric QCD
contributions to the Z-observables tend to vanish everywhere in the M1/2-M0
plane. Furthermore, values of M1/2 which are greater than 500 GeV are favoured
by the MSSM if one considers the current experimental value for the strong
coupling.


title:
Further Considerations on the CP Asymmetry in Heavy Majorana Neutrino
  Decays

abstract:
  We work out the thermodynamic equations for the decays and scatterings of
heavy Majorana neutrinos including the constraints from unitarity. The
Boltzmann equations depend on the CP asymmetry parameter which contains both, a
self-energy and a vertex correction. At thermal equilibrium there is no net
lepton asymmetry due to the CPT theorem and the unitarity constraint. We show
explicitly that deviations from thermal equilibrium create the lepton
asymmetry.


title: Wave Function Renormalization at Finite Temperature

abstract:
  We present a derivation of the medium dependent wave function renormalization
for a spinor field in presence of a thermal bath. We show that, as already
pointed out in literature, projector operators are not multiplicatively
renormalized and the effect involves a non trivial spinor dependence, which
disappears in the zero temperature covariant limit. The results, which differ
from what already found in literature, are then applied to the decay of a
massive scalar boson into two fermions and to the $\beta$--decay and crossed
related processes relevant for primordial nucleosynthesis.


title: Grand Unification of the Sterile Neutrino

abstract:
  The simplest way to simultaneously understand all existing indications of
neutrino oscillations from solar and atmospheric neutrino deficits and the LSND
experiment, seems to be to postulate a sterile neutrino. We present a realistic
grand unified model based on the gauge group $SO(10)\times SO(10)^\prime$ that
leads to the desired masses and mixings for the sterile and the known neutrinos
needed to understand the above observations while fitting those of the known
charged fermions. The model is a grand unified realization of the recently
proposed idea that the sterile neutrino is the lightest neutrino of a mirror
sector of the universe which has identical matter and gauge content as the
standard model. The two SO(10)'s operate on the two sectors in a mirror
symmetric way and are connected by a mixed Higgs representations whose net
effect is to connect the superheavy right handed neutrinos of the two sectors.


title: Non-leptonic hyperon decays in chiral perturbation theory

abstract:
  The non-leptonic hyperon decays are analyzed up to one-loop order including
all counterterms in the framework of heavy baryon chiral perturbation theory.
We use the exchange of the spin-3/2 decuplet resonances as an indication of
which low-energy constants contribute significantly to these investigated
processes . We choose four independent decay amplitudes that are not related by
isospin relations in order to perform a fit for the pertinent low-energy
constants and find a satisfactory fit both for s- and p-waves. The chiral
corrections to the lowest order forms for the s-waves are moderate whereas
there are significant modifications of the p-wave amplitudes.


title: Quarkonium production in SM Higgs decays

abstract:
  We investigate the SM Higgs decays into heavy quarkonia J/\psi and \Upsilon
in both color-singlet and color-octet mechanisms. It is found that in J/\psi
production the contribution through color-octet processes overwhelm that in
color-singlet processes all the intermediate region M_Z<M_{H^0}<2 M_w and the
fraction ratio is comparatively large, but in \Upsilon production the
contribution through color-octet mechanism is negligible.


title:
Calculation of a Class of Three-Loop Vacuum Diagrams with Two Different
  Mass Values

abstract:
  We calculate analytically a class of three-loop vacuum diagrams with two
different mass values, one of which is one-third as large as the other, using
the method of Chetyrkin, Misiak, and M\"{u}nz in the dimensional regularization
scheme. All pole terms in \epsilon=4-D (D being the space-time dimensions in a
dimensional regularization scheme) plus finite terms containing the logarithm
of mass are kept in our calculation of each diagram. It is shown that
three-loop effective potential calculated using three-loop integrals obtained
in this paper agrees, in the large-N limit, with the overlap part of
leading-order (in the large-N limit) calculation of Coleman, Jackiw, and
Politzer [Phys. Rev. D {\bf 10}, 2491 (1974)].


title: Chiral phase transition at high temperature in the QCD-like gauge theory

abstract:
  The chiral phase transition at high temperature is investigated using the
effect ive potential in the framework of the QCD-like gauge theory with a
variational a pproach. We have a second order phase transition at $T_c=136$MeV.
We also investigate numerically the temperature dependence of condensate,
$f_\pi$ a nd $a_2(T)$(coefficient of the quadratic term in the effective
potential) and es timate the critical exponents of these quantities.


title:
Investigations on the Foundation and Possible Modifications of the
  Gerasimov-Drell-Hearn Sum Rule

abstract:
  All derivations of the GDH sum rule are presented and discussed in detail,
focussing particularly on the validity of the underlying assumptions. Several
tests of the sum rule within perturbative models are reviewed. Various possible
sources of modifications of the sum rule are examined. With respect to the
current-algebra derivation, the crucial role of the infinite-momentum limit is
pointed out. A derivation is presented that exhibits the infinite-momentum
limit as its last step, opening the prospect of studying its legitimacy within
perturbative models. Adopting the Weinberg-Salam model as a testing ground, it
is shown that a modification due to an anomalous charge-density commutator is
remedied owing to the infinite-momentum limit. This finding is confirmed upon
considering $t$-channel exchange of axial-vector mesons. Several other aspects
of possible sources of modifications are investigated. Evolving the GDH sum
rule to non-zero photon virtualities $Q^2$, it is argued that different
generalizations of the GDH integral, which coincide both at $Q^2=0$ and at
large $Q^2$, may considerably deviate from one another at intermediate $Q^2$.
The limits $Q^2\to0$ and $Q^2\to\infty$ are investigated beyond leading terms.
The contribution of the pion-nucleon final state to inclusive electroproduction
is analyzed.


title: Topics in the Transport Theory of Quark-Gluon Plasma

abstract:
  A few topics of the transport theory of quark-gluon plasma are reviewed. A
derivation of the transport equations form the underlaying dynamical theory is
discussed within the $\phi^4$ model. Peculiarities of the kinetic equations of
quarks and gluons are considered and the plasma (linear) response to the color
field is studied. The chromoelectric tensor permeability is found and the
plasma oscillations are discussed. Finally, the filamentation instability in
the strongly anisotropic parton system from ultrarelativistic heavy-ion
collisions is discussed in detail.


title:
Jet Production in Deep Inelastic Electron-Photon Scattering at e+e-
  Colliders in Next-to-Leading Order QCD

abstract:
  A complete next-to-leading order QCD calculation of deep inelastic
electron-photon scattering including direct and resolved real photon components
is presented. Soft and collinear singularities are extracted using the phase
space slicing method. Application of the results for the prediction of single-
and dijet cross sections at the LEP e+e- collider are presented, using the
Snowmass jet definition. The dependence of the cross sections on the transverse
momentum and on the rapidities of the jets are discussed.


title:
Polarization Properties of Low Energy Amplitude for $\pi N \to \pi \pi
  N$ Reaction

abstract:
  The theoretical study of cross sections for polarized--target measurements of
$ \pi N \to \pi \pi N $ reactions gives evidence that the interplay between the
strong contribution from OPE mechanism and the one from isobar exchanges, which
is equally strong within isobar half--widths energy region, must result in
nontrivial polarization phenomena. The Monte--Carlo simulations for asymmetries
in $ \pi^{-} p^{\uparrow} \to \pi^{-} \pi^{+} n $ reaction at $ P_{Lab} = 360
$~MeV/c with the use of theoretical amplitudes found as solutions for
unpolarized data at $ P_{Lab} < 500 $~MeV/c provide confirmations for
significant effect. The effect is capable to discriminate between the OPE and
isobar exchanges and it is sensitive to the OPE parameters in question. This
leads to the conclusion that the decisive $\pi N \to \pi \pi N$ analysis,
aiming at determination of $ \pi \pi $--scattering lengths, must combine both
unpolarized data and polarization information. The appropriate measurements are
shown to be feasible at the already existing CHAOS spectrometer.


title: Nonvanishing zero modes in the light-front current

abstract:
  We find that the zero mode($q^{+}=0$ mode of a continuum theory) contribution
is crucial to obtain the correct values of the light-front current $J^{-}$ in
the Drell-Yan($q^{+}=0$) frame. In the exactly solvable model of
(1+1)-dimensional scalar field theory interacting with gauge fields, we
quantify the zero mode contribution and observe that the zero mode effects are
very large for the light meson form factors even though they are substantially
reduced for the heavy meson cases.


title: Probing New Physics From CP Violation in Radiative B Decays

abstract:
  When new CP-violating interactions are dominated by flavor changing neutral
particle exchanges, that may occur in many extensions of the standard model. We
examine a type 3 two Higgs doublet model and find that direct CP asymmetries
can be as large as about 25% . Time-dependent and time-integrated
mixing-induced CP asymmetries up to 85 and 40 %, respectively, are possible
without conflict with other constraints. It mainly requirs an enhanced
chromo-magnetic dipole $b\to sg$ decay to be close to the present experimental
bound.


title: Pion-nucleon scattering and isospin violation

abstract:
  I discuss low-energy pion-nucleon scattering in the framework of chiral
perturbation theory. I argue that using this theoretical method one is able to
handle the in some cases tremendous experimental accuracy (for the low partial
waves). I then show how strong and electromagnetic isospin violation can be
treated simultaneously. Some first results for neutral pion scattering and the
$\sigma$-term are given.


title: Universal Seesaw Mass Matrix Model and Neutrino Phenomenology

abstract:
  Stimulated by the recent development of the ``universal seesaw mass matrix
model", an application of the model to the neutrino mass matrix is
investigated: For the charged lepton and down-quark sectors, the model explains
the smallness of their masses $m_f$ by the conventional seesaw mechanism
M_f\simeq m_L M_F^{-1}m_R (M_F is a mass matrix of hypothetical heavy fermions
F). On the other hand, the observed fact m_t\sim \Lambda_L=O(m_L) (electroweak
scale \Lambda_L=174 GeV) seems to reject the applying of the seesaw mechanism
to the up-quark sector. However, recently, it has been found that, by taking
det M_F=0 for the up-quark sector F=U, we can understand the question of why
only top quark has a mass of the order of \Lambda_L without the
sesaw-suppression factor O(m_R)/O(M_F). For neutrino sector, the mass matrix
M_\nu is given by M_\nu \simeq m_L M_F^{-1} m_L^T (F=N), so that the masses
m_\nu are suppressed by a factor O(m_L)/O(m_R) compared with the conventional
quark and charged lepton masses. The model can naturally lead to a large mixing
\sin^2 2\theta \simeq 1. Also another model is investigated within the
framework of the universal seesaw model: the model leads to three sets of the
almost degenerate two Majorana neutrinos which are large mixing states between
the left-handed neutrinos \nu_{Li} and SU(2)_L\timesSU(2)_R singlet neutrinos
N_{1i} (i=e,\mu,\tau), so that the model can give a simultaneous explanation of
the atmospheric and solar neutrino data.


title: Matching Long and Short Distances in Large-Nc QCD

abstract:
  It is shown, with the example of the experimentally known Adler function,
that there is no matching in the intermediate region between the two asymptotic
regimes described by perturbative QCD (for the very short-distances) and by
chiral perturbation theory (for the very long-distances). We then propose to
consider an approximation of large-Nc QCD which consists in restricting the
hadronic spectrum in the channels with J^P quantum numbers 0^-, 1^-, 0^+ and
1^+ to the lightest state and treating the rest of the narrow states as a
perturbative QCD continuum; the onset of this continuum being fixed by
consistency constraints from the operator product expansion. We show how to
construct the low-energy effective Lagrangian which describes this
approximation. The number of free parameters in the resulting effective
Lagrangian can be reduced, in the chiral limit where the light quark masses are
set to zero, to just one mass scale and one dimensionless constant to all
orders in chiral perturbation theory. A comparison of the corresponding
predictions, to O(p^4) in the chiral expansion, with the phenomenologically
known couplings is also made.


title: Complete O(alpha) QED corrections to polarized Compton scattering

abstract:
  The complete QED corrections of O(alpha) to polarized Compton scattering are
calculated for finite electron mass and including the real corrections induced
by the processes e^- gamma -> e^- gamma gamma and e^- gamma -> e^- e^- e^+. All
relevant formulas are listed in a form that is well suited for a direct
implementation in computer codes. We present a detailed numerical discussion of
the O(alpha)-corrected cross section and the left-right asymmetry in the energy
range of present and future Compton polarimeters, which are used to determine
the beam polarization of high-energetic e^+- beams. For photons with energies
of a few eV and electrons with SLC energies or smaller, the corrections are of
the order of a few per mille. In the energy range of future e^+e^- colliders,
however, they reach 1-2% and cannot be neglected in a precision polarization
measurement.


title: Target Fragmentation of the Nucleon at High Energies

abstract:
  We calculate target fragmentation in $p p \to n X$ and $\gamma p \to n X $
reactions in the meson cloud picture of the nucleon. The $p p \to n X$ reaction
is used to fix the $pn\pi^+$ form factor for two different models. We take into
account the possible destruction of the residual neutron by the projectile.
Using the form factor from the hadronic reaction we calculate photoproduction
and small $x_{Bj}$ electroproduction of forward neutrons at HERA. In
photoproduction we observe about the same amount of absorption as in the
hadronic reaction. For deep inelastic events ($Q^2>10$ GeV$^2$) screening is
weaker but still present at large $Q^2$. The signature for this absorptive
rescattering is a shift of the $d\sigma/dE_n$ distribution to higher neutron
energies for photofragmentation.


title:
Weyl-van-der-Waerden formalism for helicity amplitudes of massive
  particles

abstract:
  The Weyl-van-der-Waerden spinor technique for calculating helicity amplitudes
of massive and massless particles is presented in a form that is particularly
well suited to a direct implementation in computer algebra. Moreover, we
explain how to exploit discrete symmetries and how to avoid unphysical poles in
amplitudes in practice. The efficiency of the formalism is demonstrated by
giving explicit compact results for the helicity amplitudes of the processes
gamma gamma -> f fbar, f fbar -> gamma gamma gamma, mu^- mu^+ -> f fbar gamma.


title: Comparing electroweak data with a decoupling model

abstract:
  Present data, both from direct Higgs search and from analysis of electroweak
data, are starting to become rather restrictive on the possible values for the
mass of the standard model Higgs. We discuss a new physics scenario based on a
model with decoupling (both in a linear and in a non linear version) showing
how it allows for an excellent fit to the present values of the $\epsilon$
parameters and how it widens the allowed ranges for the Higgs mass (thought as
elementary in the linear version, or as composite in the non linear one).


title: Constraints on leptophobic Z' models from electroweak experiments

abstract:
  We study the constraints from updated electroweak data on the three
leptophobic Z' models, the ${\eta}$ model with an appropriate $U(1)'-U(1)_Y$
kinetic mixing, a Z' model motivated by the flipped SU(5) \times U(1)
unification, and the phenomenological Z' model of Agashe, Graesser, and
Hinchliffe.
  The $Z-Z'$ mixing effects are parametrized in terms of a positive
contribution to the $T$ parameter, $T_{new}$, and the effective mass mixing
parameter, $\bar{\xi}$. All the theoretical predictions for the $Z$ boson
parameters, the $W$ boson mass and the observables in low-energy neutral
current experiments are presented together with the standard model radiative
corrections. The allowed region in the ($\bar{\xi},T_{new}$) plane is shown for
the three models. The 95% CL lower limit on the heavier mass eigenstate $Z_2$
is given as a function of the effective $Z-Z'$ mixing parameter $\zeta$.


title: $Z'$ bosons in supersymmetric $E_6$ models confront electroweak data

abstract:
  We study constraints on additional $Z'$ bosons predicted in the
supersymmetric (SUSY) $E_6$ models by using the updated results of electroweak
experiments -- $Z$-pole experiments, $m_W$ measurements and low-energy neutral
current (LENC) experiments. We find that the effects of $Z$-$Z'$ mixing are
parametrized by (i) a tree-level contribution to the $T$-parameter, (ii) the
effective $Z$-$Z'$ mass mixing angle $\xibar$. In addition, the effect of the
direct exchange of the heavier mass eigenstate $Z_2$ in the LENC processes is
parametrized by (iii) a contact term $\contact$. We give the theoretical
predictions for the observables in the electroweak experiments together with
the standard model radiative corrections. Constraints on $T_{\rm new}$ and
$\xibar$ from the $Z$-pole and $m_W$ experiments and those on $\contact$ from
the LENC experiments are separately shown. Impacts of the kinetic mixing
between the ${\rm U(1)}_Y$ and ${\rm U(1)'}$ gauge bosons on the
$\chi^2$-analysis are studied. We show the 95% CL lower mass limit of $Z_2$ as
a function of the effective $Z$-$Z'$ mixing parameter $\zeta$, a combination of
the mass and kinetic mixings. Theoretical prediction on $\zeta$ and $g_E$ is
found for the $\chi, \psi, \eta$ and $\nu$ models by assuming the minimal
particle content of the SUSY $E_6$ models. In a certain region of the parameter
space, the $Z_2$ boson mass in the detectable range of LHC is still allowed.


title: Hadronic Axion Model in Gauge-Mediated Supersymmetry Breaking

abstract:
  A simple hadronic axion model is proposed in the framework of gauge-mediated
supersymmetry breaking. Dynamics of Peccei-Quinn symmetry breaking is governed
by supersymmetry breaking effects and the Peccei-Quinn breaking scale $f_{PQ}$
is inversely proportional to the gravitino mass. The gravitino mass range which
corresponds to the axion window $f_{PQ} \simeq 10^{9}$ GeV -- $10^{13}$ GeV
lies in the region predicted by gauge-mediated supersymmetry breaking models.
The model is also shown to be cosmologically viable.


title: Intermittency analysis in diffractive DIS processes

abstract:
  It is pointed out in this talk that ``the colorless objects'' in diffractive
scattering in the small-$x_B$ region can be probed by measuring the scaled
factorial moments of final-state-hadrons and the dependence of their scaling
behavior upon the diffractive kinematic variables. The Monte Carlo
implementation of RAPGAP and JETSET are discussed as illustrative examples. The
results of these model-calculations show in particular that inclusion of the
contributions from the photon gluon fusion processes can considerably enlarge
the power of the scaled factorial moments. The significant $x_B$-dependence of
intermittency index in small-$x_B$ region in this MC analyses shows the
hadronic final states depend very much on the lifetime of the exchanged
colorless object $c_0^*$. The dependence of the intermittency index upon
$x_\pomeron$, $Q^2$ and $\beta$ are also discussed.


title: Further Analysis of $B \to \eta^{\prime} K(K^*),\eta K(K^*)$ Processes

abstract:
  Combining three mechanisms, we reanalysis processes of $B \to \eta^{\prime}
K(K^*),\eta K(K^*)$ and calculate their branching ratios. The results are
compared with other mechanisms in the literature. The striking feature of the
gluon fusion mechanism is emphasized and its experimental test is discussed.


title: Decay $\Lambda_b \to p l \bar \nu$ in QCD sum rules

abstract:
  The $\Lambda_b \to p$ semileptonic decay is analyzed by using QCD sum rules
within the framework of heavy quark effective theory. The Isgur-Wise function
of $\Lambda_b \to p l \bar\nu$ has been calculated. The decay width is given.


title: General Gauge Field Theory

abstract:
  In this paper, we will construct a gauge field model, in which the masses of
gauge fields are non-zero and the local gauge symmetry is strictly preserved. A
SU(N) gauge field model is discussed in details in this paper. In the limit
$\alpha \longrightarrow 0$ or $\alpha \longrightarrow \infty$, the gauge field
model discussed in this paper will return to Yang-Mills gauge field model. This
theory could be regarded as theoretical development of Yang-Mills gauge field
theory.


title:
Determination of $|V_{cb}|$ from the polarization of vector meson in the
  semileptonic decay of $B$ and $B_c$ meson

abstract:
  Since the degree of polarization of the vector particle in semileptonic decay
strongly influences the decay width of the particles, it can be used as a
measure of CKM matrix elements. We show that |V_{cb}| can be determined from
the measurement of polarization of vector meson in B,B_c --> V l nu decay,
where $V$ is vector meson.


title: Black Hole Baryogenesis

abstract:
  We find that the Hawking radiation of black holes can create the baryon
number in the Higgs phase vacuum of the extended standard model with 2-Higgs
doublets. We propose new scenarios of baryogenesis based on the black holes,
and one of our scenarios can explain the origin of baryon number in our
universe, if most of the matter existed as primordial black holes.


title: Polarization in B_c -> J/\psi mu nu

abstract:
  We study the polarization of the J/\psi meson of the B_c -> J/\psi mu nu
decay process, followed by J/\psi -> mu+ mu-, with the help of the heavy-quark
spin symmetry formalism (HQSS). We adapt the ISGW wave function. Due to the
clean signature of the decay mode, measurements of the polarization of the
J/\psi meson can play a special role in extracting |V_{cb}|, the quark
mixing-matrix element. We compare the results with the predictions of other
quark models.


title:
A Model with Simultaneous Dynamical Breaking of Supersymmetry and GUT
  Gauge Symmetry

abstract:
  We try to construct a model in which supersymmetry and grand unified gauge
symmetry are dynamically broken at the same time. In this model SUSY breaking
is mediated mainly by massive vector multiplet, and a new solution for the mu
problem is proposed.


title:
Large breaking of isospin symmetry in an electroweak SU(2)left x U(1)
  gauge theory of J=0 mesons: the case of K -> Pi Pi decays

abstract:
  K -> Pi Pi decays are investigated in the framework of the SU(2)left x U(1)
gauge theory of J=0 mesons proposed in ref.[1], to which is added an
interaction between mesons respecting the two symmetries generally attributed
to strong interactions, flavour symmetry and parity conservation. It is shown
that the damping of the K+ -> Pi+ Pi0 amplitude with respect to the ones of
Kshort -> Pi Pi results from a cancelation between the W and Z gauge bosons.
The ratio of the two types of amplitudes is sensitive to the spectrum of
electroweak (pseudoscalar and scalar) mass eigenstates, an in particular to the
mass of the Higgs boson. In the case where scalars and pseudoscalars are
degenerate, the amplitudes satisfy the lower bound |(Kshort -> Pi+ Pi-) / (K+
-> Pi+ Pi0)| > 1/tan(Weinberg angle)^2.


title:
Mapping of composite hadrons into elementary hadrons and effective
  hadronic Hamiltonians

abstract:
  A mapping technique is used to derive in the context of constituent quark
models effective Hamiltonians that involve explicit hadron degrees of freedom.
The technique is based on the ideas of mapping between physical and ideal Fock
spaces and shares similarities with the quasiparticle method of Weinberg.
Starting with the Fock-space representation of single-hadron states, a change
of representation is implemented by a unitary transformation such that
composites are redescribed by elementary Bose and Fermi field operators in an
extended Fock space. When the unitary transformation is applied to the
microscopic quark Hamiltonian, effective, hermitian Hamiltonians with a clear
physical interpretation are obtained. Applications and comparisons with other
composite-particle formalisms of the recent literature are made using the
nonrelativistic quark model.


title:
Renormalization of Chiral-Even Twist-3 Light-cone Wave Functions for
  Vector Mesons in QCD

abstract:
  We present the one-loop anomalous dimension matrices for the chiral-even
twist-3 (nonsinglet) conformal operators, which govern the scale-dependence of
the vector meson light-cone wave functions through the conformal expansion. It
is clarified that the constraints from the charge-conjugation invariance and
the chirality conservation allow only one independent anomalous dimension
matrix for each conformal spin.


title: Resonant and nonresonant contributions to the weak $D\to Vl^+l^-$ decays

abstract:
  The Cabibbo suppressed decays $D\to Vl^+l^-$ (V is light vector meson)
present in principle the opportunity to observe the short distance FCNC
transition $c\to ul^+l^-$, which is sensitive to physics beyond the Standard
Model. We analyze these as well as the Cabibbo allowed $D \to V l^+ l^-$ decays
within the Standard Model, where in addition to the short distance dynamics
also the long distance dynamics is present. The long distance contribution is
induced by the effective nonleptonic weak Lagrangian accompanied by the
emission of a virtual photon, which occurs resonantly via conversion from a
vector meson $\rho^0, \omega$ or $\phi$ or nonresonantly as direct emission
from a $D$ meson. We calculate the branching ratios for all $D\to Vl^+l^-$
decays using the model, which combines heavy quark symmetry and chiral
perturbation theory. The short distance contribution due to $c\to ul^+l^-$
transition, which is present only in the Cabibbo suppressed decays, is found to
be three orders of magnitude smaller than the long distance contribution. The
branching ratios well above $10^{-7}$ for Cabibbo suppressed decays could
signal new physics. The most frequent decays are the Cabibbo allowed decays,
which are expected at the rates, that are not much lower than the present
experimental upper limit: $D_s^+\to \rho^+\mu^+\mu^-$ is expected at the
branching ratio of approximately $3\cdot 10^{-5}$, while $D^0\to\bar
K^{*0}\mu^+\mu^-$ is expected at $1.7\cdot 10^{-6}$.


title: Is there a mass dependence in the spin structure of baryons?

abstract:
  We analyze the axial-vector form factors of the nucleon-hyperon system in a
model with SU(3)$_{\text{flavor}}$ symmetry breaking due to mass dependent
quark spin polarizations. This mass dependence is deduced from an analysis of
magnetic moment data, and implies that the spin contributions from the quarks
to a baryon decrease with the mass of the baryon. When applied to the
axial-vector form factors, these mass dependent spin polarizations bring the
various sum-rules from the quark model in better agreement with experimental
data. As a consequence our analysis leads to a reduced value for the total spin
polarization of the proton.


title: Transverse polarization of quark pairs created in string fragmentation

abstract:
  Classical arguments predict that the quark and the antiquark of a pair
created during string fragmentation are both transversely polarized in the
direction of \hat z \times \vec q_T, where z is the direction of the pull
exerted by the string on the antiquark and \vec q_T (-\vec q_T) is the
transverse momentum of the quark (antiquark). The existence of this effect at
the quantum-mechanical level is investigated by considering two analogous
processes involving the tunnel effect in a strong field: (1) dissociation of
the positronium atom (2) electron pair creation. In case (1) the positronium is
taken in the 3P_0 state to simulate the vacuum quantum numbers J^PC = 0^++.
Using the nonrelativistic WKB method, the final electron and positron are
indeed found to be transversely polarized along \hat z \times \vec p_T. On the
contrary, case (2), treated with the Dirac equation, shows no correlation
between transverse polarization and transverse momentum both when the field is
uniform and when it depends on z and t. The pair is nevertheless produced in a
triplet spin state. The difference between these two results and their
relevance to transverse spin asymmetry in inclusive reactions is discussed.


title:
Higher order QCD Corrections to Fragmentation Functions in e^+~e^-
  Annihilation

abstract:
  We analyze the second order QCD corrections to the fragmentation functions
F_^H_k(x,Q^2) (k=T,L,A) which are measured in e^+~e^- annihilation From these
fragmentation functions one can derive the integrated transverse (sigma_T),
longitudinal (sigma_L) and asymmetric (sigma_A) cross sections. The sum
sigma_{tot}=sigma_T+sigma_L corrected up to order alpha_s^2 agrees with the
well known result in the literature. It turns out that the order alpha_s^2
corrections to the transverse and asymmetric quantities are small in contrast
to our findings for F_L^H(x,Q^2) and sigma_L where they turn out to be large.
Therefore in the latter case one gets a better agreement between the
theoretical predictions and the data obtained from he LEP experiments.


title: On polynomial approximation of the static vortex in Abelian Higgs model

abstract:
  The static vortex solution in Abelian Higgs model with small ratio of vector
and Higgs particle masses is considered. Several formulae approximating this
solution are discussed. The accuracy of these approximations is tested by
numerical computations.


title: Coherent bremsstrahlung at the BEPC collider

abstract:
  Coherent bremsstrahlung (CBS) is a sopecific type of radiation at colliders
with short bunches. In the present paper we calculate the main characteristic
of CBS for the BEPC collider. At this collider $d N_\gamma \sim 3\cdot 10^8
dE_\gamma /E_\gamma $ photons of CBS will be emitted for a single collision of
the beams in the energy range $E_\gamma$ smaller than 240 eV.
  It seems that CBS can be a potential tool for optimazing collisions and for
measuring beam parameters. Indeed, the bunch length $\sigma_z$ can be found
from the CBS spectrum because critical energy $E_c \propto 1/\sigma_z$; the
horizontal transverse bunch size $\sigma_x $ is related to $dN_\gamma \propto
1/\sigma_x^2$. Besides, CBS may be very useful for a fast control over an
impact parameter $R$ between the colliding bunch axex because a dependence of
$dN_\gamma $ on $R$ has a very specific behavior.
  It seems quite interesting to investigate this type of radiation on the BEPC
collider (for example, in the range of a visible light with the rate about $3
\cdot 10^{14} $ photons per second) and apply it for the fast beam control.


title:
Nonequilibrium Corrections to the Spectra of Massless Neutrinos in the
  Early Universe - Addendum

abstract:
  We repeat our previous calculation of the spectrum distortion of massless
neutrinos in the early universe with a considerably better accuracy and
corrected for a missing numerical factor in one of the two ways of calculations
presented in hep-ph/9703315. Now both ways of calculations are in perfect
agreement and we essentially reproduce our old results presented in the
abstract of the paper and used in the calculations of light element abundances.
We disagree with the criticism of our calculations presented in
astro-ph/9712199.


title: Heavy Quark Physics

abstract:
  A review of Heavy Quark Effective Theory and Non Relativistic Quantum
Chromondynamics is given. Some applications are discussed.


title: Duality, Superstrings and M-theory

abstract:
  In these notes, based on a talk given at the Rencontres de Moriond, I give a
simple introduction to the tremendous progress that has been made during the
last few years towards the understanding of strong-coupling phenomena in
quantum gauge theories and superstring theories.


title: New Results on the Hadronic Contributions to alpha(M_Z) and to (g-2)_mu

abstract:
  We reevaluate the dispersion integrals of the leading order hadronic
contributions to the running of the QED fine structure constant alpha(s) at
s=M_Z^2, and to the anomalous magnetic moments of the muon and the electron.
Finite-energy QCD sum rule techniques complete the data from e+e- annihilation
and tau decays at low energy and at the cc-bar threshold. Global quark-hadron
duality is assumed in order to resolve the integrals using the Operator Product
Expansion wherever it is applicable.
  We obtain delta_alpha_had(M_Z) = (276.3 +/- 1.6)x10^{-4} yielding
alpha^{-1}(M_Z) = 128.933 +/- 0.021, and a_mu^had = (692.4 +/- 6.2)x10^{-10}
with which we find for the complete Standard Model prediction a_mu^SM =
(11659159.6 +/- 6.7)x10^{-10}. For the electron, the hadronic contribution
reads a_e^had = (187.5 +/- 1.8)x10^{-14}.


title: Effective Field Theory for a Three-Brane Universe

abstract:
  A general effective field theory formalism is presented which describes the
low-energy dynamics of a 3-brane universe. In this scenario an arbitrary
four-dimensional particle theory, such as the Standard Model, is constrained to
live on the world-volume of a (3+1)-dimensional hypersurface, or ``3-brane'',
which in turn fluctuates in a higher-dimensional, gravitating spacetime. The
inclusion of chiral fermions on the 3-brane is given careful treatment. The
power-counting needed to renormalize quantum amplitudes of the effective theory
is also discussed. The effective theory has a finite domain of validity,
restricting it to processes at low enough energies that the internal structure
of the 3-brane cannot be resolved.


title:
Signal and Backgrounds for the Single Production of Scalar and Vector
  Leptoquarks at the LHC

abstract:
  We perform a detailed analysis of the potentiality of the CERN Large Hadron
Collider to study the single production of leptoquarks via $pp \to e^\pm q\to$
leptoquark $\to e^\pm q$, with $e^\pm$ generated by the splitting of photons
radiated by the protons. Working with the most general $SU(2)_L \otimes U(1)_Y$
invariant effective lagrangian for scalar and vector leptoquarks, we analyze in
detail the leptoquark signals and backgrounds that lead to a final state
containing an $e^\pm$ and a hard jet with approximately balanced transverse
momenta. Our results indicate that the LHC will be able to discover leptoquarks
with masses up to 2--3 TeV, depending on their type, for Yukawa couplings of
the order of the electromagnetic one.


title: Nonthermal Supermassive Dark Matter

abstract:
  We discuss several cosmological production mechanisms for nonthermal
supermassive dark matter and argue that dark matter may be elementary particles
of mass much greater than the weak scale. Searches for dark matter should not
be limited to weakly interacting particles with mass of the order of the weak
scale, but should extend into the supermassive range as well.


title: CP-Violation through Scalar Tau Oscillation

abstract:
  We point out that oscillation between the two scalar tau (stau) mass
eigenstates can give rise to CP-violation if some parameters appearing in the
stau or chargino/neutralino mass matrices are complex. If stau^+ and stau^-
decay into different charginos or neutralinos, rate asymmetries as large as 20%
are possible. If both staus decay directly into tau + LSP, CP-violation can in
principle still be observed through an energy asymmetry of the tau decay
products, but this asymmetry never exceeds the percent level. Even the rate
asymmetries become small if the mass splitting between the two stau mass
eigenstates is larger than 1%.


title: Signals of phase transition in atmospheric showers

abstract:
  We discuss collective effects like percolation, quark gluon plasma, or string
fusion and their effect on the longitudinal development of high energy showers
in air. It is shown that iron-air showers could develop more slowly than
expected and produce the observed change in the slope of $X_max$ at the highest
energies.


title: The Bose-Einstein effect and the joint WW decay

abstract:
  The influence of the Bose - Einstein interference effect on the joint WW
hadronic decay is discussed. It is shown that the weight method incorporating
this effect into Monte Carlo generators produces in a natural way an excess of
average multiplicity as compared to the independent decay of two W bosons. The
quantitative results for the average multiplicity and momentum distribution of
charged pions, obtained with a simple parametrization of weights compatible
with the observed shape of the "Bose - Einstein ratio", agree well with the
existing data.


title: Long Range Forces from Pseudoscalar Exchange

abstract:
  Using dispersion theoretic techniques, we consider coherent long range forces
arising from double pseudoscalar exchange among fermions. We find that Yukawa
type coupling leads to $1/r^3$ spin independent attractive potentials whereas
derivative coupling renders $1/r^5$ spin independent repulsive potentials.


title: Large-N and Vacuum Alignment in Topcolor Models

abstract:
  Topcolor and topcolor-assisted technicolor provide examples of dynamical
electroweak symmetry breaking which include top-condensation, thereby naturally
incorporating a heavy top quark. In this note we discuss the roles of the
Nambu-Jona-Lasinio (NJL) and large-N approximations often used in
phenomenological analyses of these models. We show that, in order to provide
for top-condensation but not bottom-condensation, the top-color coupling must
be adjusted to equal the critical value for chiral symmetry breaking up to
O(1/N) in any theory in which the isospin-violating ``tilting'' interaction is
a U(1) gauge interaction. A consequence of these considerations is that the
potentially dangerous ``bottom-pions'' are naturally light. We also show that
the contributions to rho-1 previously estimated are of leading-order in N, are
not included in the usual NJL analysis, and are the result of
``vacuum-alignment''.


title:
The Dynamical and Static Casimir Effects and the Thermodynamic
  Instability

abstract:
  The dynamical Casimir effect for the ideal case of two perfectly conducting
non-charged parallel plates, is discussed using the zero-point energy summation
method to the first order in perturbation theory. We show that it is possible
to create photon radiation when the two plates are modulated rapidly in time.
Moreover we point out that the static Casimir energy between two conducting
non-charged parallel plates violates the thermodynamic stability condition
normally associated with the second law of thermodynamics.


title: Neutrino Flavor Mixing and Oscillations in Field Theory

abstract:
  The Lagrangian that is normally associated with Dirac neutrinos is analyzed
in a complete and simple way through field theory. It is found that the
elements of the neutrino mass matrix are field strength renormalization
constants and that the flavor fields can be directly applied to the
one-particle energy states through these rescaling factors. Moreover this
Lagrangian describes neutrinos which are in a state of mixed flavor at any
space-time point and therefore does not describe the phenomenology of neutrino
oscillations properly, except in the ultra-relativistic limit where such a
description is possible.


title: Jet Physics: Theoretical Overview

abstract:
  I review the status of fixed order jet Monte Carlos and briefly discuss the
prospects for next-to-next-to-leading order calculations. I present a general
purpose next-to-leading order Monte Carlo program for four jet event shape
observables in electron-positron annihilation and present some estimates of the
light jet mass and narrow jet broadening distributions. Finally, I discuss an
estimate of the strong coupling constant using the measured energy evolution of
the average value of event shape variables such as thrust and heavy jet mass.


title: The connection between the DRED and NSVZ renormalisation schemes

abstract:
  We explore the relationship between the DRED and NSVZ schemes. Using certain
exact results for the soft scalar mass $\beta$-function, we derive the
transformation of $\alpha^{\DRED}$ to $\alpha^{\NSVZ}$ through terms of order
$\alpha^4$. We thus incidentally determine $\beta_{\alpha}^{\DRED}$ through
four loops, and we compare our result to a previous Pad\'e Approximant
prediction.


title:
Thermal Restoration of Chiral Symmetry in Supersymmetric
  Nambu-Jona-Lasinio Model with Soft SUSY Breaking

abstract:
  The supersymmetric version of the Nambu-Jona-Lasinio model is investigated in
connection with the chiral symmetry breaking induced by a soft SUSY breaking
term. It is found that the broken chiral symmetry due to the soft breaking term
is restored at suitably high temperature and the symmetry restoration occurs as
first-order phase transitions. The critical temperature at which the chiral
symmetry is restored is determined as a function of the strength of the soft
breaking term and the field coupling constant. The dynamical fermion mass is
calculated at finite temperature. Some possible applications to the breaking
scenario of unified field theories are discussed.


title: QCD Power Corrections from a Simple Model for the Running Coupling

abstract:
  A simple parametrization of the QCD running coupling at low scales is
introduced and used to illustrate various schemes for the estimation of
non-perturbative power corrections. The `infrared matching' scheme proposed
earlier gives satisfactory results when combined with next-to-leading (or
higher) order perturbative predictions. Estimates based on renormalons are
shown to be inconsistent with universal behaviour of the running coupling.


title: Non-equilibrium dynamics of a thermal plasma in a gravitational field

abstract:
  We introduce functional methods to study the non-equilibrium dynamics of a
quantum massless scalar field at finite temperature in a gravitational field.
We calculate the Close Time Path (CTP) effective action and, using its formal
equivalence with the influence functional, derive the noise and dissipation
kernels of the quantum open system in terms of quantities in thermodynamical
equilibrium. Using this fact, we formally prove the existence of a
Fluctuation-Dissipation Relation (FDR) at all temperatures between the quantum
fluctuations of the plasma in thermal equilibrium and the energy dissipated by
the external gravitational field. What is new is the identification of a
stochastic source (noise) term arising from the quantum and thermal
fluctuations in the plasma field, and the derivation of a Langevin-type
equation which describes the non-equilibrium dynamics of the gravitational
field influenced by the plasma. The back reaction of the plasma on the
gravitational field is embodied in the FDR. From the CTP effective action the
contribution of the quantum scalar field to the thermal graviton polarization
tensor can also be derived and it is shown to agree with other techniques, most
notably, Linear Response Theory (LRT). We show the connection between the LRT,
which is applicable for near-equilibrium conditions and the functional methods
used in this work which are useful for fully non-equilibrium conditions.


title: Z' Physics from Strings

abstract:
  Many extensions of the standard model, especially grand unified theories and
superstring models, predict the existence of additional Z' bosons and
associated exotic chiral supermultiplets. It has recently been argued that for
classes of string motivated models with supergravity mediated supersymmetry
breaking there are two scenarios for the additional Z's: either the mass is in
the accessible range < O(1 TeV), providing a natural solution to the mu problem
and implications for the Higgs and sparticle masses and for the LSP; or, when
the breaking is associated with a D-flat direction, at an intermediate scale,
providing a possible explanation for the hierarchies of quark and charged
lepton masses and new possibilities for neutrino masses. Related work,
examining the detailed structure of specific perturbative string vacua for D
and F-flat directions, surviving U(1)'s and exotics, and effective couplings,
is briefly described.


title: Single Pion Transitions of Charmed Baryons

abstract:
  The $SU(2N_{f}) X O(3)$ constituent quark model symmetry of the light diquark
system are used to analyze single pion transitions of S-wave to S-wave and
P-wave to S-wave heavy baryons. We show that the Heavy Quark Symmetry (HQS)
coupling factors are given in terms of the three independent couplings
$g_{\Sigma_Q \Lambda_Q \pi}, f_{\Lambda_{Q1} \Sigma_Q \pi}$ and
$f_{\Lambda^{*}_{Q1} \Sigma_Q \pi}$.
  Light-Front quark model spin wave functions are, then, employed to calculate
these couplings and to predict decay rates of single pion transitions between
charm baryon states.


title:
Four-fermion heavy quark operators and light current amplitudes in heavy
  flavor hadrons

abstract:
  We introduce and study the properties of the "color-straight" four-quark
operators containing heavy and light quark fields. They are of the form (\bar
b\Gamma_b b)(\bar q\Gamma_q q) where both brackets are color singlets. Their
expectation values include the bulk of the nonfactorizable contributions to the
nonleptonic decay widths of heavy hadrons. The expectation values of the
color-straight operators in the heavy hadrons are related to the momentum
integrals of the elastic light-quark formfactors of the respective heavy
hadron. We calculate the asymptotic behavior of the light-current formfactors
of heavy hadrons and show that the actual decrease is 1/(q^2)^3/2 rather than
1/q^4. The two-loop hybrid anomalous dimensions of the four-quark operators and
their mixing (absent in the first loop) are obtained. Using plausible models
for the elastic formfactors, we estimate the expectation values of the
color-straight operators in the heavy mesons and baryons. Improved estimates
will be possible in the future with new data on the radiative decays of heavy
hadrons. We give the Wilson coefficients of the four-fermion operators in the
1/m_b expansion of the inclusive widths and discuss the numerical predictions.
Estimates of the nonfactorizable expectation values are given.


title: Neutron Electric Dipole Moment and Spontaneous CP Breaking

abstract:
  In a model where CP is spontaneously broken, the aspon model, it is shown by
extending previous arguments about B decay and the value of
$Re(\epsilon^{'}/\epsilon)$ in the kaon system, that the neutron electric
dipole moment $D_n$ is bounded from below by $D_n \geq 10^{-29}$e.-cm.


title: Topology of Hadronic Flows for Higgs Production at Hadron Colliders

abstract:
  Hadronic radiation provides a tool to distinguish different topologies of
colour flow in hard scattering processes. We study the structure of hadronic
flow corresponding to Higgs production and decay in high-energy hadron-hadron
collisions. In particular, the signal gg -> H -> b anti-b and background gg ->
b anti-b processes are shown to have very different radiation patterns, and
this may provide an useful additional method for distinguishing Higgs signal
events from the QCD background.


title: Transition Radiation of the Neutrino Toroid Dipole Moment

abstract:
  We discuss the transition radiation of a neutrino induced by its toroid
dipole moment ($\tau$) when crossing the interface between two different media
with different refraction indices. A neutrino of 1 MeV energy emits
approximately $10^{-40}$ keV at $\tau=e\sqrt{2}G_F/\pi^2$. This effect depends
very slightly on the neutrino mass and has a finite value in the massless
limit.


title: QCD-Instantons at HERA

abstract:
  A ``fiducial'' kinematical region for our calculations of instanton
(I)-induced processes at HERA within I-perturbation theory is extracted from
recent lattice simulations of QCD. Moreover, we present the finalized I-induced
cross-sections exhibiting a strongly reduced residual dependence on the
renormalization scale.


title: Critical Behavior of phi^4-Theory from the Thermal Renormalization Group

abstract:
  We discuss the universal critical behavior of a selfinteracting scalar field
theory at finite temperature as obtained from approximate solutions to
nonperturbative renormalization group (RG) equations. We employ a formulation
of the RG-equations in real-time formalism which is particularly well suited
for a discussion of the thermal behavior of theories which are weakly coupled
at T=0. We obtain the equation of state and critical exponents of the theory
with a few percent accuracy even for a relatively simple approximation to the
exact renormalization group equations.

categories: hep-ph cond-mat.stat-mech hep-lat nucl-th


title: The Phenomenology of Extra Neutral Gauge Bosons

abstract:
  The phenomenological constraints on extra neutral gauge bosons at present and
at future colliders are reviewed. Special attention is paid to the influence of
radiative corrections, systematic errors, and kinematic cuts on the Z'
constraints. Simple estimates of the Z' constraints from different reactions
are derived. They make the physical origin of these constraints transparent.
The results existing in the literature are summarized and compared with the
estimates. The consequence of model assumptions on the Z' constraints is
discussed. The paper starts with an overview of Z' parameters and the possible
links between them by model assumptions. It continues with a discussion of Z'
limits and Z' measurements in different reactions at e+e- and mu+mu- colliders.
It follows an overview of the corresponding limits at proton colliders.
Possible Z' constraints from other reactions as ep collisions, atomic parity
violation, neutrino scattering and cosmology are briefly mentioned.


title: Wilson Fermions on a Transverse Lattice

abstract:
  In the light-front formulation of field theory, it is possible to write down
a chirally invariant mass term. It thus appears as if one could solve the
species doubling problem on a light-front quantized transverse lattice in a
chirally invariant way. However, upon introducing link fields and after
renormalizing, one finds exactly the same LF Hamiltonian as if one had started
from the standard Wilson action in the first place. The (light-front) chirally
invariant transverse lattice regularization is thus not chirally invariant in
the conventional sense. As an application of the Wilson formulation for
fermions on a $\perp$ lattice, we calculate spectrum, distribution functions
and distribution amplitudes for mesons below $2 GeV$ in a truncated Fock space.


title: Factorization and Scaling in Hadronic Diffraction

abstract:
  In standard Regge theory with a pomeron intercept a(0)=1+\epsilon, the
contribution of the tripe-pomeron amplitude to the t=0 differential cross
section for single diffraction dissociation has the form d\sigma/dM^2(t=0) \sim
s^{2\epsilon}/(M^2)^{1+\epsilon}. For \epsilon>0, this form, which is based on
factorization, does not scale with energy. From an analysis of p-p and p-pbar
data from fixed target to collider energies, we find that such scaling actually
holds, signaling a breakdown of factorization. Phenomenologically, this result
can be obtained from a scaling law in diffraction, which is embedded in the
hypothesis of pomeron flux renormalization introduced to unitarize the triple
pomeron amplitude.


title: Renormalization of Supersymmetric Theories

abstract:
  We review the renormalization of the electroweak sector of the standard
model. The derivation also applies to the minimal supersymmetric standard
model. We discuss regularization and the relation between the threshold
corrections and the renormalization group equations. We consider the
corrections to many precision observables, including MW and sin^2 theta^eff. We
show that global fits to the data exclude regions of supersymmetric model
parameter space and lead to lower bounds on superpartner masses.


title: A new evaluation of the t->cH decay width in the standard model

abstract:
  We present a new calculation of the t->cH decay rate in the standard model.
We find that the corresponding branching fraction is B(t->cH) \sim 10^{-13} -
10^{-14} for M_Z < m_H < 2 M_W, that is about 6 orders of magnitude less than
previously evaluated, and usually quoted in the literature.


title: new type of pion interferometry formula

abstract:
  New type of pion interferometry formulas is derived, in which not only the
correlator but also the pion multiplicity is taken consideration.
  The method to get information about initial emission probability of the
unsymmetrized Bosons is given.


title: Chiral symmetry

abstract:
  Broken chiral symmetry has become the basis for a unified treatment of
hadronic interactions at low energies. After reviewing mechanisms for
spontaneous chiral symmetry breaking, I outline the construction of the
low--energy effective field theory of the Standard Model called chiral
perturbation theory. The loop expansion and the renormalization procedure for
this nonrenormalizable quantum field theory are developed. Evidence for the
standard scenario with a large quark condensate is presented, in particular
from high--statistics lattice calculations of the meson mass spectrum. Elastic
pion--pion scattering is discussed as an example of a complete calculation to
O(p^6) in the low--energy expansion. The meson--baryon system is the subject of
the last lecture. After a short summary of heavy baryon chiral perturbation
theory, a recent analysis of pion--nucleon scattering to O(p^3) is reviewed.
Finally, I describe some very recent progress in the chiral approach to the
nucleon--nucleon interaction.


title:
CP Violation and Lifetime Differences of Neutral B Mesons from
  Correlated B^0-B^0bar Pairs

abstract:
  We present a technique to determine the CP violating phases, as well as, the
lifetime differences of the mass eigenstates for both $B_d$ and $B_s$, by
considering correlated $B\bar{B}$ pairs produced at the $\Upsilon$ resonances.
We do not require a detailed time dependent study, but only partial time
integrated rates, with the tag time, either preceding or following the decay of
the other $B$ meson to a final state f. f may be a CP eigenstate or a non-CP
eigenstate.


title:
Observing Correlated Production of Defects-Antidefects in Liquid
  Crystals

abstract:
  We present observations of strength one defects and antidefects formed in
isotropic-nematic phase transition in a thin layer of nematic liquid crystals,
using a cross-polarizer setup. We measure the widths of the distributions of
{\it net} winding number in small regions, and determine the exponent
characterizing the correlation between defects and antidefects to be
0.26$\pm$0.11, in very good agreement with the value 1/4 predicted by the
Kibble mechanism for defect production. We also describe a novel technique to
determine the director distribution in observations of defect networks.


title: Spectator Effects in Heavy Quark Effective Theory at O(1/m_Q^3)

abstract:
  We complete the one loop renormalization of the HQET lagrangian at O(1/m_Q^3)
including four fermion operators with two heavy and two light quark fields in
the operator basis. It is shown that as a consequence the short distance
coefficients of the operators bilinear in the heavy quark field receive
nontrivial corrections.


title: Diffractive DIS and QCD: past, present and future

abstract:
  In this paper I review the theoretical progresses in studying the diffractive
DIS in the colour--dipole approach.


title: Interconnection phenomena in $W^+W^-$ and $t\bar t$ events

abstract:
  I will attempt to survey some selected physics issues on QCD interconnection
phenomena in the processes $e^+e^-\to W^+W^-\to$ 4 jets and $e^+e^-\to t\bar t
\to b W^+\bar b W^-$. Possible consequences for LEP2 and future linear $e^+e^-$
colliders are briefly discussed.


title: Alternatives to Axion Production and Detection

abstract:
  We consider axion production during the formation of a quark-gluon plasma in
relativistic heavy-ion collisions and discuss a possible detection scheme.


title: The Spontaneous Breakdown of the Vacuum

abstract:
  We discuss the spontaneous breakdown of the vacuum by a strong
electromagnetic field as observed in SLAC experiment E-144. We show that the
data follow the Schwinger non-perturbative result obtained for a static field.


title: Fast CP Violation

abstract:
  $B$ flavor tagging will be extensively studied at the asymmetric $B$
factories due to its importance in CP asymmetry measurements. The primary
tagging modes are the semileptonic decays of the $b$ (lepton tag), or the
hadronic $b \to c (\to s)$ decays (kaon tag). We suggest that looking for time
dependent CP asymmetries in events where one $B$ is tagged leptonically and the
other one is tagged with a kaon could result in an early detection of CP
violation. Although in the Standard Model these asymmetries are expected to be
small, $\sim 1%$, they could be measured with about the same amount of data as
in the ``gold-plated'' decay $B_d \to \psi K_S$. In the presence of physics
beyond the Standard Model, these asymmetries could be as large as $\sim 5%$,
and the first CP violation signal in the $B$ system may show up in these
events. We give explicit examples of new physics scenarios where this occurs.


title:
Polarized rho mesons and the asymmetry between Delta d^bar(x) and Delta
  u^bar(x) in the sea of the nucleon

abstract:
  We present a calculation of the polarized rho meson cloud in a nucleon using
time-ordered perturbation theory in two different variants advocated in the
literature. We calculate the induced difference between the distributions Delta
d^bar(x) and Delta u^bar(x). We use a recent lattice calculation to motivate an
ansatz for the polarized valence quark distribution of the rho meson. Our
calculations show that the two theoretical approaches give vastly different
results. We conclude that Delta d^bar(x) - Delta u^bar(x) can be of relevant
size with important consequences for the combined fits of polarized
distribution functions.


title: Hidden Sector Gaugino Condensation and the Model-independent Axion

abstract:
  In the effective field theory framework, we consider the effect of
supersymmetry breaking via gaugino condensation and supergravity in the hidden
sector gauge group on the hidden sector vacuum angle $\theta_h$. The $\theta_h$
parameter dependence of the potential yields phenomenologically acceptable
invisible axion solutions if the $U(1)_R$ symmetry is broken down to a discrete
subgroup $Z_N$ with $N\ge 3$ (N=4 is marginal). Anomalous U(1) superstring
models are good candidates for this invisible axion resolution of the strong CP
puzzle.


title: Two-Higgs-Doublet-Models and Radiative CP Violation

abstract:
  We discuss the feasibility of spontaneous CP violation being induced by
radiative corrections in 2HDM's. Specifically, we analyze the cases of
gaugino/higgsino effect on MSSM, and a new model with an extra exotic quark
doublet. The new model, while demonstrating well the Georgi-Pais theorem, is
also expected to be phenomenlogically interesting.


title: Interactions of a Single Goldstino

abstract:
  The single goldstino interaction is given by the goldstino derivative
coupling to the supercurrent. In an alternative description, the goldstino
couples nonderivatively. We give a simple method to establish the equivalence
of the two approaches, valid to all orders in perturbation theory, and for any
scattering process involving an arbitrary number of particles, but with a
single external goldstino. In the meantime, we find in the nonderivative form
of the goldstino interaction a new quartic vertex that has been overlooked, and
terms that were included incorrectly in the literature. The phenomenological
implication of this new quartic operator is discussed.


title:
Lepton mass generation and family number violation mechanism in the
  $SU(6)\otimes U(1)$ model

abstract:
  Lepton family number violation processes arise in the $SU(6)_L \otimes
U(1)_Y$ model due to the presence of an extra neutral gauge boson, Z$'$, with
family changing couplings, and due to the fact that this model demands the
existence of heavy exotic leptons. The mixing of the standard Z with Z$'$ and
the mixing of ordinary leptons with exotic ones induce together family changing
couplings on the Z and therefore nonvanishing rates for lepton family number
violation processes, such as $Z \to e \bar{\mu}$, $\mu \to ee\bar{e}$ and $\mu
\to e\gamma$. Additional contributions to the processes $\mu \to e \gamma$ and
$\mu \to ee \bar{e}$ are induced from the mass generation mechanism. This last
type of contributions may compete with the above one, depending on the masses
of the scalars which participate in the diagrams which generate radiatively the
masses of the charged leptons. Using the experimental data we compute some
bounds for the mixings parameters and for the masses of the scalars.


title: Dark Matter Axions in Models of String Cosmology

abstract:
  Axions are produced during a period of dilaton-driven inflation by
amplification of quantum fluctuations. We show that for some range of string
cosmology parameters and some range of axion masses, primordial axions may
constitute a large fraction of the present energy density in the universe in
the form of cold dark matter. Due to the periodic nature of the axion potential
energy density fluctuations are strongly suppressed. The spectrum of primordial
axions is not thermal, allowing a small fraction of the axions to remain
relativistic until quite late.


title:
Long-Distance 1/N_c Corrections to Density-Density Operators in K --> pi
  pi Decays

abstract:
  In this talk we discuss the general method to calculate loop corrections to
Delta S=1 density-density operators in the 1/N_c approach. As a result we
present the long-distance evolution of the operators Q_6 and Q_8 to O(p^0/N_c)
in the chiral and the 1/N_c expansions.


title:
New Analysis of the Delta I = 1/2 Rule in the 1/N_c Expansion for K -->
  pi pi Decays

abstract:
  We analyze long-distance contributions to the K --> pi pi amplitudes relevant
for the Delta I = 1/2 selection rule in the framework of the 1/N_c expansion.
We use a modified prescription for the identification of meson momenta in the
chiral loop corrections to gain a consistent matching with the short-distance
part. Our approach involves a separation of non-factorizable and factorizable
1/N_c corrections. Along these lines we calculate the one-loop contributions
from the lowest order lagrangian. Our main result is an additional enhancement
of the Delta I = 1/2 channel amplitude which we find in good agreement with
experiment.


title:
Nonequilibrium dynamics of fermions in a spatially homogeneous scalar
  background field

abstract:
  We consider the time evolution of systems in which a spatially homogeneous
scalar field is coupled to fermions. The quantum back-reaction is taken into
account in one-loop approximation. We set up the basic equations and their
renormalization in a form suitable for numerical computations. The initial
singularities appearing in the renormalized equations are removed by a
Bogoliubov transformation. The equations are then generalized to those in a
spatially flat Friedmann-Robertson-Walker universe.
  We have implemented the Minkowski space equations numerically and present
results for the time evolution with various parameter sets. We find that
fermion fluctuations are not in general as ineffective as assumed previously
but show interesting features which should be studied further. In an especially
interesting example we find that fermionic fluctuations can ``catalyze'' the
evolution of bosonic fluctuations.


title: Looking for the Unexpected: Direct CP Violation in B -> X_s gamma Decays

abstract:
  The observation of a sizable direct CP asymmetry in the inclusive decays B ->
X_s gamma would be a clean signal of New Physics. In the Standard Model, this
asymmetry is below 1% in magnitude. In extensions of the Standard Model with
new CP-violating couplings, large asymmetries are possible without conflicting
with the experimental value of the B -> X_s gamma branching ratio. In
particular, large asymmetries arise naturally in models with enhanced
chromo-magnetic dipole transitions. Some generic examples of such models are
explored and their implications for the semileptonic branching ratio and charm
yield in B decays discussed.


title: Supercooling of rapidly expanding quark-gluon plasma

abstract:
  We reexamine the scenario of homogeneous nucleation of the quark-gluon plasma
produced in ultra-relativistic heavy ion collisions. A generalization of the
standard nucleation theory to rapidly expanding system is proposed. The
nucleation rate is derived via the new scaling parameter $\lambda_Z$. It is
shown that the size distribution of hadronic clusters plays an important role
in the dynamics of the phase transition. The longitudinally expanding system is
supercooled to about 3-6%, then it is reheated, and the hadronization is
completed within 6-10 fm/c, i.e. 5-10 times faster than it was estimated
earlier, in a strongly nonequilibrium way.


title: Are there quasistable strange baryons with anticharm or antibeauty?

abstract:
  In some models, exotic baryons with strangeness and anticharm or antibeauty
should exist and even be stable against strong decay. We consider the stability
of such possible exotic baryons, which in the constituent quark picture are
called pentaquarks (each is composed of four quarks and an antiquark). Our
model is based on diquark clustering and supersymmetry in hadrons, and assumes
that the spin-dependent force between quarks arises from one-gluon exchange. In
the model, a pentaquark with strangeness and anticharm can decay strongly, but
an analogous pentaquark with an antibeauty quark is stable except for weak
decay.


title: Exclusive Hadronic D Decays to eta' and eta

abstract:
  Hadronic decay modes $D^0\to(\bar K^0, \bar K^{*0})\eta,\eta'$ and
$(D^+,D_s^+)\to(\pi^+,\rho^+)\eta,\eta'$ are studied in the generalized
factorization approach. Form factors for $(D,D_s^+)\to(\eta,\eta')$ transitions
are carefully evaluated by taking into account the wave function normalization
of the eta and eta'. The predicted branching ratios are generally in agreement
with experiment except for $D^0\to\bar K^0\eta', D^+\to\pi^+\eta$ and
$D_s^+\to\rho^+\eta'$; the calculated decay rates for the first two decay modes
are too small by an order of magnitude. We show that the weak decays $D^0\to
K^-\pi^+$ and $D^+\to K^+\bar K^0$ followed by resonance-induced final-state
interactions (FSI), which are amenable technically, are able to enhance the
branching ratios of $D^0\to\bar K^0\eta'$ and $D^+\to\pi^+\eta$ dramatically
without affecting the agreement between theory and experiment for $D^0\to\bar
K^0\eta$ and $D^+\to\pi^+\eta'$. We argue that it is difficult to understand
the observed large decay rates of $D_s^+\to \rho^+\eta'$ and $\rho^+\eta$
simultaneously; FSI, W-annihilation and the production of excess eta' from
gluons are not helpful in this regard. The large discrepancy between the
factorization hypothesis and experiment for the ratio of $D_s^+\to\rho^+ \eta'$
and $D_s^+\to\eta' e^+\nu$ remains as an enigma.


title: Phenomenology of the $B - 3 L_\tau$ Gauge Boson

abstract:
  Assuming the existence of a gauge boson $X$ which couples to $B - 3 L_\tau$,
we discuss the present experimental constraints on $g_X$ and $m_X$ from $Z \to
l^+ l^-$ and $Z \to \bar f f X~(f = q, \nu_\tau, \tau)$. We also discuss the
discovery potential of $X$ at hadron colliders through its decay into $\tau^+
\tau^-$ pairs. In the scenario where all three charged leptons (and their
neutrinos) mix, lepton flavor nonconservation through $X$ becomes possible and
provides another experimental probe into this hypothesis.


title: Small-x evolution with Q dependence and unitarity

abstract:
  We propose a modified Balitsky-Fadin-Kuraev-Lipatov equation from the
viewpoint of the resummation technique, which contains an intrinsic dependence
on momentum transfer Q, and satisfies the unitarity bound. The idea is to relax
the strong rapidity ordering and to restrict phase space for real gluon
emissions in the evaluation of the BFKL kernel. It is shown that the power-law
rise of the gluon distribution function with the small Bjorken variable x turns
into a logarithmic rise, and that the predictions for the proton structure
function $F_2(x,Q^2)$ are consistent with the HERA data.


title: The description of $F_2$ at low $Q^2$

abstract:
  We analyse the data for the proton structure function $F_2$ over the entire
$Q^2$ domain, including especially low $Q^2$, in terms of perturbative and
non-perturbative QCD contributions. The small distance configurations are given
by perturbative QCD, while the large distance contributions are given by the
vector dominance model and, for the higher mass $q \bar{q}$ states, by the
additive quark approach. The interference between states of different
$q\bar{q}$ mass (in the perturbative contribution) is found to play a crucial
role in obtaining an excellent description of the data throughout the whole
$Q^2$ region, including photoproduction.


title: Supersymmetric D-term Inflation and B-ball Baryogenesis

abstract:
  We consider the B-ball cosmology of the MSSM in the context of D-term
inflation models where the reheating temperature is determined by the
Affleck-Dine mechanism to be of the order of 1 GeV. We show that such a low
reheating temperature can arise quite naturally as the result of a symmetry
which is required to maintain the flatness of the inflaton potential. In this
case the B-balls will decay well after the freeze-out temperature of the LSP,
allowing baryons and cold dark matter to originate primarily from B-ball
decays.


title: New constraints on R-parity violation from proton stability

abstract:
  We derive stringent upper bounds on all the $(\lambda''_{ijk} \mu_l)$-type
combinations from the consideration of proton stability, where
$\lambda''_{ijk}$ are baryon-number-violating trilinear couplings and $\mu_l$
are lepton-number-violating bilinear mass parameters in a R-parity-violating
supersymmetric theory.


title:
Second order contributions to elastic large-angle Bhabha scattering
  cross-section

abstract:
  The cross-section of (quasi-)elastic large-angle electron-positron scattering
at high energies is calculated. Radiative corrections of the orders O(\alpha^2
L^2) and O(\alpha^2 L), besides pure two-loop box contributions, are explicitly
calculated. In the second order we considered the following sources of
corrections: 1) Virtual photonic corrections coming from squares of 1-loop
level amplitudes and their relevant interferences (vertex-type and box-type
Feynman diagrams). 2) Double soft photon emission and one-loop corrections to
single soft photon emission. The results are presented in an analytical form.


title: Chiral Symmetry Restoration in the Instanton Liquid at Finite Density

abstract:
  The properties of the QCD partition function at finite chemical potential are
studied within the instanton liquid model. It is shown that the density
dependence of the quark-induced instanton-antiinstanton (I-A) interaction leads
to the formation of topologically neutral I-A pairs ('molecules'), resulting in
a first order chiral phase transition at a critical chemical potential
$\mu_q^c\simeq 310$ MeV. At somewhat higher densities ($\mu_q\ge360$ MeV), the
quark Fermi surface becomes instable with respect to diquark condensation
(Cooper pairs) generating BCS-type energy gaps of order 50 MeV.


title: The Problem of \alpha_s in Supersymmetric Unified Theories

abstract:
  It is shown that in SO(10) there is a general connection between the
suppression of higgsino mediated proton decay and the value of $\alpha_s$.
However, agreement with the experimental value of $\alpha_s$ can be obtained if
there are relatively large negative threshold corrections to $\alpha_s$ coming
from superheavy split multiplets. It is shown that such split multiplets can
arise in SO(10) without fine-tuning of parameters.


title: Study of Inclusive Multi-Ring Events from Atmospheric Neutrinos

abstract:
  The current analysis of atmospheric neutrinos by the Super-Kamiokande
Collaboration is based only on fully-contained one-ring events and partially
contained events. We show that the up-down ratio of fully-contained, inclusive,
multi-ring events gives an independent test of the atmospheric neutrino
anomaly, without the need for particle identification. Moreover, this class of
events is rich in neutral current events and hence gives crucial information
for discriminating between oscillations of \nu_\mu into \nu_{e, \tau} and
\nu_s.


title: Signatures of the Tricritical Point in QCD

abstract:
  Several approaches to QCD with two massless quarks at finite temperature T
and baryon chemical potential mu suggest the existence of a tricritical point
on the boundary of the phase with spontaneously broken chiral symmetry. In QCD
with massive quarks there is then a critical point at the end of a first order
transition line. We discuss possible experimental signatures of this point,
which provide information about its location and properties. We propose a
combination of event-by-event observables, including suppressed fluctuations in
T and mu and, simultaneously, enhanced fluctuations in the multiplicity of soft
pions.


title:
Nonperturbative Description of Deep Inelastic Structure Functions in
  Light-Front QCD

abstract:
  We explore the deep inelastic structure functions of hadrons
nonperturbatively in an inverse power expansion of the light-front energy of
the probe in the framework of light-front QCD. We arrive at the general
expressions for various structure functions as the Fourier transform of matrix
elements of different components of bilocal vector and axial vector currents on
the light-front in a straightforward manner. The complexities of the structure
functions are mainly carried by the multi-parton wave functions of the hadrons,
while, the bilocal currents have a dynamically dependent yet simple structure
on the light-front in this description. We also present a novel analysis of the
power corrections based on light-front power counting which resolves some
ambiguities of the conventional twist analysis in deep inelastic processes.
Further, the factorization theorem and the scale evolution of the structure
functions are presented in this formalism by using old-fashioned light-front
time-ordered perturbation theory with multi-parton wave functions.
Nonperturbative QCD dynamics underlying the structure functions can be explored
in the same framework. Once the nonperturbative multi-parton wave functions are
known from low-energy light-front QCD, a complete description of deep inelastic
structure functions can be realized.


title:
Deep Inelastic Structure Functions in Light-Front QCD: Radiative
  Corrections

abstract:
  Recently, we have introduced a unified theory to deal with perturbative and
non-perturbative QCD contributions to hadronic structure functions in deep
inelastic scattering. This formulation is realized by combining the coordinate
space approach based on light-front current algebra techniques and the momentum
space approach based on Fock space expansion methods in the Hamiltonian
formalism of light-front field theory. In this work we show how a perturbative
analysis in the light-front Hamiltonian formalism leads to the factorization
scheme we have proposed recently. The analysis also shows that the scaling
violations due to perturbative QCD corrections can be rather easily addressed
in this framework by simply replacing the hadron target by dressed parton
target and then carrying out a systematic expansion in the coupling constant
$\alpha_s$ based on the perturbative QCD expansion of the dressed parton
target. The tools employed for this calculation are those available from
light-front old-fashioned perturbation theory. We present the complete set of
calculations of unpolarized and polarized deep inelastic structure functions to
order $\alpha_s$. We extract the relevant splitting functions in all the cases.
We explicitly verify all the sum rules to order $\alpha_s$. We demonstrate the
validity of approximations made in the derivation of the new factorization
scheme. This is achieved with the help of detailed calculations of the
evolution of structure function of a composite system carried out using
multi-parton wavefunctions.


title: Lepton-Flavor Violation in Supersymmetric Models

abstract:
  Theoretical aspects of lepton-flavor violating (LFV) processes on the
supersymmetric models are reviewed. In particular, we show that, assuming the
minimal supergravity scenario, the LFV interaction at the higher energy scale
leads to the the LFV processes, which may be accessible in near future
experiments.


title: Light active and sterile neutrinos from compositeness

abstract:
  Neutrinos can have naturally small Dirac masses if the Standard Model singlet
right-handed neutrinos are light composite fermions. Theories which produce
light composite fermions typically generate many of them, three of which can
marry the left-handed neutrinos with small Dirac masses. The rest can serve as
sterile states which can mix with the Standard Model neutrinos. We present
explicit models illustrating this idea.


title:
A New Analysis of B_6^(1/2), B_8^(3/2), and the Delta I=1/2 Rule in the
  1/N_c Expansion for K --> pi pi Decays

abstract:
  We present a new calculation of long-distance contributions to the K --> pi
pi amplitudes using the 1/N_c expansion within the framework of chiral
perturbation theory. Along these lines we compute the chiral loop corrections
to the operators Q_1, Q_2, Q_6, and Q_8. In the numerical analysis we present
values for B_6^(1/2) and B_8^(3/2). We discuss also the implications for a
theoretical understanding of the Delta I=1/2 selection rule.


title: QCD Anomalous Structure of Electron

abstract:
  The parton content of the electron is analyzed within perturbative QCD. It is
shown that electron acquires an anomalous component from QCD, analogously to
photon. The evolution equations for the `exclusive' and `inclusive' electron
structure function are constructed and solved numerically in the asymptotic
$Q^2$ region.


title: Strange magnetism in the nucleon

abstract:
  Using heavy baryon chiral perturbation theory to one loop, we derive an
analytic and parameter-free expression for the momentum dependence of the
strange magnetic form factor of the nucleon $G_M^{(s)} (Q^2)$ and its
corresponding radius. This should be considered as a lower bound. We also
derive a model-independent relation between the isoscalar magnetic and the
strange magnetic form factors of the nucleon based on chiral symmetry and SU(3)
only. This gives an upper bound on the strange magnetic form factor. We use
these limites to derive bounds on the strange magnetic moment of the proton
from the recent measurement of $G_M^{(s)} (Q^2=0.1 GeV^2)$ by the SAMPLE
collaboration. We stress the relevance of this result for the on-going and
future experimental programs at various electron machines.