title:
The J/\psi Production Associated with a Hard Photon and the Color-Octet
  Singnature in e^+e^- Annihilation

abstract:
  J/\psi production associated with a hard photon in e^+e^- annihilation, being
of QED nature, is invastigated thoroughly in the paper. To show its influence
on the observation of the color-octet singnature in the e^+e^- annihilation via
J/\psi inclusive production, the cross sections of the J/\psi productions
through different mechanisms at various energies are compared quantatively by
presenting them in figures together. The contribution from the production
associated with a hard photon to the inclusive production of J/\psi is pointed
out to be significant at the concerned energies, thus the influence from it on
the observation of the color-octet signature should be dealt with carefully.


title:
On finite--temperature and --density radiative corrections to the
  neutrino effective potential in the early Universe

abstract:
  Finite-temperature and -density radiative corrections to the neutrino
effective potential in the otherwise CP-symmetric early Universe are considered
in the real-time approach of Thermal Field Theory. A consistent perturbation
theory endowed with the hard thermal loop resummation techniques developed by
Braaten and Pisarski is applied. Special attention is focused on the question
whether such corrections can generate any nonzero contribution to the
CP-symmetric part of the neutrino potential, if the contact approximation for
the W-propagator is used.


title: Finite temperature effects on CP violating asymmetries

abstract:
  We compute the CP violating decay asymmetries relevant for baryogenesis
scenarios involving the out of equilibrium decays of heavy particles, including
the finite temperature effects arising from the background of light thermal
particles which are present during the decay epoch. Thermal effects can modify
the size of CP violation by a sizeable fraction in the decay of scalar
particles, but we find interesting cancellations in the thermal corrections
affecting the asymmetries in the decays of fermions, as well as in the decay of
scalars in supersymmetric theories. We also estimate the effects which arise
from the motion of the decaying particles with respect to the background
plasma.


title: New Insight in Dynamical Symmetry Breaking via Imaginary Part Analysis

abstract:
  We present a new method solving Schwinger-Dyson equations in gauge theories
via imaginary part analysis. The self-consistency equation for the fermion
self-energy can be reduced from a numerical unstable eigenvalue problem to a
finite dimensional integral which can be solved easily. We can therefore derive
relations between the dynamically generated fermion mass, the coupling, the
gauge boson mass and the cutoff. For infinite cutoff the fermion mass is
independent of the gauge boson mass which should be the relevant scale. Thus
for a defined fermion mass it is necessary to incorporate a running coupling
constant. Within our framework this is possible in a well defined way. The
results are reasonable and in agreement with the renormalization group in the
asymptotic regime.


title:
Thirring's low-energy theorem and its generalizations in the electroweak
  Standard Model

abstract:
  The radiative corrections to Compton scattering vanish in the low-energy
limit in all orders of perturbation theory. This theorem, which is well-known
for Abelian gauge theories, is proved in the electroweak Standard Model.
Moreover, analogous theorems are derived for photon scattering off other
charged particles, in particular W bosons. Since the theorems follow from gauge
invariance and on-shell renormalization, their derivation is most conveniently
performed in the framework of the background-field method.


title:
Unitarity Corrections and High Field Strengths in High Energy Hard
  Collisions

abstract:
  Unitarity corrections to the BFKL description of high energy hard scattering
are viewed in large $N_c$ QCD in light-cone quantization. In a center of mass
frame unitarity corrections to high energy hard scattering are manifestly
perturbatively calculable and unrelated to questions of parton saturation. In a
frame where one of the hadrons is initially at rest unitarity corrections are
related to parton saturation effects and involve potential strengths $A_\mu
\sim 1/g.$ In such a frame we describe the high energy scattering in terms of
the expectation value of a Wilson loop. The large potentials $A_\mu \sim 1/g$
are shown to be pure gauge terms allowing perturbation theory to again describe
unitarity corrections and parton saturation effects. Genuine nonperturbative
effects only come in at energies well beyond those energies where unitarity
constraints first become important.


title: Nonperturbative effects in inclusive $B\to X_s\gamma$

abstract:
  Uncertainties in the theoretical prediction for the inclusive $\bar B\to
X_s\gamma$ decay rate are examined. Certain nonperturbative effects involving a
virtual $c\bar c$ loop, which are calculable using the operator product
expansion, are discussed.


title: CP-Violating Solitons in the Minimal Supersymmetric Standard Model

abstract:
  We study non-topological and CP-violating static wall solutions in the
framework of the Minimal Supersymmetric Standard Model. We show that such
membranes, characterized by a non-trivial winding of the relative $U(1)$ phase
of the two Higgs fields in the direction orthogonal to the wall, exist for
small values of the mass of the CP-odd Higgs boson when loop corrections to the
Higgs potential are included. Although their present-day existence is excluded
by experimental bounds, we argue why they may have existed in the early
universe with important cosmological consequences.


title: Unitarity effects in DIS

abstract:
  We argue that diffractive DIS, dominated by soft interactions, is probably
the unique process which allows us to observe unitarity effects in DIS. Guided
by a close analogy between the diffractive dissociation of a highly virtual
photon and the elastic scattering of hadrons we propose a specific procedure to
analyse the data in order to detect the onset of the unitarity limit. Lacking
appropriate data, we use the predictions of a realistic model as an input for
our analysis, to demonstrate that the output unitarity signal is sufficiently
large to be detectable.


title: Towards dynamical mass calculations

abstract:
  SU(2)xU(1) electroweak gauge model without Higgs sector is extended by a new
vector field C interacting with leptons and quarks of both chiralities. This
interaction is treated under a dynamical assumption in a self-consistent
approximation. Fermion masses are calculated in terms of new Abelian
hypercharges, and the intermediate boson masses are calculated in terms of the
fermion masses by sum rules. Self-consistency requires a rich sector of heavy
spin-1 collective fermion-antifermion excitations.


title: Three Flavour Majorana Neutrinos with Magnetic Moments in a Supernova

abstract:
  The resonant transition effects MSW and NSFP for three flavour Majorana
neutrinos in a supernova are considered, where the transition magnetic moments
are likely to play a relevant role in neutrino physics. In this scenario, the
deformed thermal neutrino distributions are obtained for different choices of
the electron-tau mixing angle. Detailed predictions for the future large
neutrino detectors are also given in terms of the ratio between the spectra of
recoil electrons for deformed and undeformed spectra.


title: Investigations on CPT Invariance at B-Factories

abstract:
  We study the sensitivity of an asymmetric B-factory to indirect CPT violating
effects. We find that both dilepton signals and nonleptonic asymmetries can be
used to bound the space of parameters describing possible CPT violation in the
mixing matrix of the neutral B system.


title: Quark mixing, CP violation and rare decays after the top quark discovery

abstract:
  We review the highlights of quark mixing, particle-antiparticle mixing, CP
violation and rare K- and B-decays in the Standard Model. The top quark
discovery, the precise measurement of its mass, the improved knowledge of the
couplings $V_{cb}$ and $V_{ub}$, and the calculations of NLO short distance QCD
corrections improved considerably the predictions for various decay rates, the
determination of the couplings $V_{td}$ and $V_{ts}$ and of the complex phase
in the Cabibbo-Kobayashi-Maskawa matrix. After presenting the general
theoretical framework for weak decays, we discuss the following topics in
detail: i) the CKM matrix, its most convenient parametrizations and the
unitarity triangle, ii) the CP-violating parameter $\epsilon_K$ and
$B^0_{d,s}-\bar B^0_{d,s}$ mixings, iii) the ratio $\epsilon'/\epsilon$, iv)
the rare K-decays $K_L\to\pi^0e^+e^-$, $K^+\to\pi^+\nu\bar\nu$,
$K_L\to\pi^0\nu\bar\nu$ and $K_L\to\mu^+\mu^-$, v) the radiative decays $B\to
X_s\gamma$ and $B\to X_s l^+l^-$, vi) the rare B-decays $B\to
X_{s,d}\nu\bar\nu$ and $B_{d,s}\to l^+l^-$, vii) CP violation in neutral and
charged B-decays putting emphasis on clean determinations of the angles of the
unitarity triangle, and viii) the role of electroweak penguins in B-decays. We
present several future visions demonstrating very clearly the great potential
of CP asymmetries in B-decays and of clean K-decays such as $K^+\to\pi^+\nu
\bar\nu$ and $K_L\to\pi^0\nu\bar\nu$ in the determination of the CKM parameters
and in decisive testing of the Standard Model. An outlook for the coming years
ends our review.


title:
Virtual photons in SU(2) chiral perturbation theory and electromagnetic
  corrections to $\pi\pi$ scattering

abstract:
  We construct the generating functional of two flavor chiral perturbation
theory including the effects of virtual photons in the one loop approximation.
As an application, we calculate the electromagnetic corrections to the elastic
$\pi\pi$ scattering amplitude, in particular to its S--wave threshold
parameters. Numerical estimates are given for the reaction $\pi^0 \pi^0 \to
\pi^0 \pi^0$. These electromagnetic effects are found to be smaller than the
hadronic two-loop corrections for the scattering length $a_0$. The effective
range $b_0$ increases by 36% due to the unitary cusp.


title:
Higher Fock states and power counting in exclusive P-wave quarkonium
  decays

abstract:
  Exclusive processes at large momentum transfer Q factor into perturbatively
calculable short-distance parts and long-distance hadronic wave functions.
Usually, only contributions from the leading Fock states have to be included to
leading order in 1/Q. We show that for exclusive decays of P-wave quarkonia the
contribution from the next-higher Fock state |Q Qbar g> contributes at the same
order in 1/Q. We investigate how the constituent gluon attaches to the hard
process in order to form colour-singlet final-state hadrons and argue that a
single additional long-distance factor is sufficient to parametrize the size of
its contribution. Incorporating transverse degrees of freedom and Sudakov
factors, our results are perturbatively stable in the sense that soft
phase-space contributions are largely suppressed. Explicit calculations yield
good agreement with data on chi_{c J} decays into pairs of pions, kaons, and
etas. We also comment on J/psi decays into two pions.


title:
Intrinsic Charm of Vector Mesons: A Possible Solution of the "rho pi"
  Puzzle

abstract:
  An outstanding mystery of charmonium physics is why the J/\psi decays
prominently to pseudoscalar plus vector meson channels, such as J/\psi -> \rho
\pi and J/\psi -> K^*K, whereas the \psi'(2S) does not. We show that such
decays of J/\psi and their suppression for \psi'(2S) follow naturally from the
existence of intrinsic charm |qbar q cbar c> Fock components of the light
vector mesons.


title: Comment on $Z'$'s and the H1 and ZEUS High $Q^2$ Anomalies

abstract:
  We investigate the effects of extra neutral gauge bosons on the high $Q^2$
region of the $e^+p \to e^+ X$ cross section at $\sqrt{s}=300$ GeV. We found
that the only models with electroweak strength coupling, typical of extended
gauge theories, that give a better fit to the H1 and ZEUS high $Q^2$ data than
the standard model, are ruled out by existing data from the Tevatron. From
general scaling arguments, using the allowed contact interactions, the only
allowed models with $Z'$'s would be those with strong couplings although even
in this case the statistical evidence is not compelling.


title: Generalized Electric Polarizability of the Proton from Skyrme Model

abstract:
  We calculate the electric polarizability $\alpha(q^2)$ of the proton in
virtual Compton scattering using the Skyrme model. The $q^2$ dependence of the
polarizability is comparable with the predictions obtained from the
non-relativistic quark model and the linear sigma model. The chiral behaviors
of our $\alpha(0)$ and $d^2\alpha(0)/d^2q^2$ agree with the results of the
chiral perturbation theory. The discrepancy can be traced back to the
contribution of the intermediate $\Delta$ state degenerate with the $N$ which
is a characteristic of a large-$N_C$ model.


title: Strongly Coupled Messenger Gauge Theory

abstract:
  We consider gauge-mediated models of supersymmetry (SUSY) breaking with
strongly coupled nonabelian messenger gauge theory. After integrating out the
SUSY-breaking and messenger sectors, we directly see that the effective Kahler
potential transmits the SUSY breaking to the standard model sector.


title: Bose-Einstein Correlations in the Lund Model

abstract:
  By providing the Lund Model fragmentation process with a quantum-mechanical
framework we extend the results of previous work to situations where there are
very many identical bosons. We investigate the features of the weight
distributions in some detail and in particular exhibit three-particle
BE-correlations, the influence on the rho-spectrum and the difference between
charged and neutral pion correlations.


title: Aspects of Neutrino Detection of Neutralino Dark Matter

abstract:
  Neutralino dark matter, and in particular different aspects of its detection
at neutrino telescopes, has been studied within the Minimal Supersymmetric
extension of the Standard Model, the MSSM. The relic density of neutralinos has
been calculated using sophisticated routines for integrating the annihilation
cross section and the Boltzmann equation. As a new element, so called
coannihilation processes between the lightest neutralino and the heavier
neutralinos and charginos have also been included for any neutralino mass and
composition. The detection rates at neutrino telescopes have been evaluated for
neutralino annihilation in both the Sun and the Earth using detailed Monte
Carlo simulations of the whole chain of processes from the neutralino
annihilation products in the core of the Sun or the Earth to detectable muons
at a neutrino telescope. A comparison with other searches for supersymmetry at
accelerators and direct dark matter searches is also given. The signal muon
fluxes that current and future neutrino telescopes can probe and the
improvement in sensitivity that can be achieved with angular and/or energy
resolution of the neutrino-induced muons has also been investigated. The
question of whether the neutralino mass can be extracted from the width of the
muon angular distribution, if a signal flux is observed, has also been
addressed.


title:
Leading logarithmic QCD corrections to the B_s --> \gamma \gamma decay
  rate including long-distance effects through B_s --> \phi \gamma --> \gamma
  \gamma

abstract:
  We present leading logarithmic QCD corrections to the decay B_s -->
\gamma\gamma in the Standard Model. Further, the form factor F_{1}(0) of B_s
--> \phi\gamma is calculated in the framework of QCD sum rules and found to be
in agreement with the result existing in the literature. Using Vector Meson
Dominance model, the amplitude for B_s --> \phi \gamma -->\gamma\gamma is
calculated as an estimate of the O_7-type contributions to the long-distance
effects in the B_s --> \gamma\gamma decay. The resulting branching ratio B(B_s
--> \gamma \gamma)_{SD+LD_{O_7}} is analysed in view of its strong dependence
on the non-perturbative parameter $\bar{\Lambda}_s$, describing bound state
effects, and the renormalization scale $\mu$. .


title: Direct hadron production in ultrarelativistic heavy ion collisions

abstract:
  Hadrons emitted by the pre-surface layer of quark-gluon plasma (QGP) before
phase transition into hadronic gas are considered as possible source of direct
information about QGP. It is shown that these hadrons dominate at soft p_t if
QGP is created in ultrarelativistic heavy ion collisions.


title: Effect of the 3K background radiation on ultrahigh energy cosmic rays

abstract:
  In this work we re-examine the opacity of the cosmic background radiation to
the propagation of extremely high energy cosmic rays. We use the continuous
energy loss approximation to provide spectral modification factors for several
hypothesized cosmic ray sources. Earlier problems with this approximation are
resolved including the effects of resonances other than the $\Delta$.


title: Dynamical Supersymmetric Inflation

abstract:
  We propose a new class of inflationary models in which the scalar field
potential governing inflation is generated by the same non-perturbative gauge
dynamics that may lead to supersymmetry breaking. Such models satisfy
constraints from cosmic microwave background measurements for natural values of
the fundamental parameters in the theory. In addition, they have two
particularly interesting characteristics: a ``blue'' spectrum of scalar
perturbations, and an upper bound on the total amount of inflation possible.


title: Supersymmetric Baryogenesis and Flavor Physics

abstract:
  We study the flavor physics implications of baryogenesis in the Minimal
Supersymmetric Standard Model. Enhanced $B-\bar B$ mixing and $b \to s \gamma$
rates are generic to all scenarios. Depending on the origin of the CP violating
phase responsible for baryogenesis there could be a large neutron electric
dipole moment, large CP violating $D-\bar D$ mixing or CP violation in top
quark production. We discuss how the combination of these measurements with the
requirement of baryogenesis shed light on the MSSM parameter space and the
source of CP violation.


title: The Supersymmetric Flavor Problem and Mu to E Plus Gamma

abstract:
  The supersymmetric $SU(3)\times SU(2)\times U(1)$ theory with minimal
particle content and general soft supersymmetry breaking terms has 110 physical
parameters in its flavor sector: 30 masses, 39 mixing angles, and 41 phases.
These parameters contain many new measurable sources of flavor violations
unless either the sparticle mass splittings and mixing angles are small or the
sparticle masses are large.
  In chapter 1 of this report, we discuss the origins of sparticle mass
splittings and mixing angles in a theory explaining flavor, and we review the
upper limits of sparticle masses that arise from naturalness among the
electroweak breaking parameters. By examining the flavor changing processes
$\mu \to e + \gamma$ and $K^0 - \bar{K}^0$ mixing, we show it is not possible
to simultaneously satisfy the requirements of flavor differentiation among
sparticles and naturalness in electroweak breaking. This indicates that a
crucial ingredient is missing from our understanding of the theory. We discuss
one possible solution in which the messengers that transmit supersymmetry
breaking to ordinary particles are much lighter than $M_{Planck}$.
  In our analysis, we found the most important constraint was the process $\mu
\to e + \gamma$. Furthermore, this process is currently being experimentally
investigated. In spite of its importance, the complete branching ratio
calculation has not yet been done. In chapter 2 we present the full one-loop
calculation for $\mu \to e + \gamma$.


title: SU(3)_flavor analysis of two-body weak decays of charmed baryons

abstract:
  We study two-body weak decays of charmed baryons \Lambda_c and \Xi_c into an
octet or decuplet baryon and a pseudoscalar meson employing the SU(3) flavor
symmetry. Using certain measured Cabibbo-favored modes, we fix the reduced
amplitudes and predict the branching ratios of various decays of charmed
baryons in the Cabibbo-enhanced, -suppressed and -doubly suppressed modes.


title:
Three-Point Spectral Functions in $\phi^3_6$ Theory at Finite
  Temperature

abstract:
  We derive a set of relations among the thermal components of the 3-point
function and its spectral representations at finite temperature in the
real-time formalism. We then use these to explicitly calculate the 3-point
spectral densities for $\phi^3_6$ theory and relate the result to the case of
hot QCD.


title: P and T odd nucleon-nucleon interaction in a two higgs doublet model

abstract:
  A two higgs doublet model with tree level natural flavor conservation can
lead to P and T odd nucleon-nucleon (NN) interaction through tree level Feynman
diagrams. In this article we estimate the magnitudes of the parameters that
characterize the strength of the S-PS type of NN interaction. Stringent
constraints on the parameters can be derived from the measurement of EDM's of
Xe, Cs and Hg atoms in the ground state. We show that the predicted values of
the parameters lie close to such constraints provided ${\absvt\over \absvo }$
is large.


title:
Chiral Symmetry Breaking in QED in a Magnetic Field at Finite
  Temperature

abstract:
  The catalysis of chiral symmetry breaking in the massless weakly coupled QED
in a magnetic field at finite temperature is studied. The temperature of the
symmetry restoration is estimated analytically as $T_c\simeq m_{dyn}$, where
$m_{dyn}$ is the dynamical mass of a fermion at zero temperature.


title:
Double parton scattering of hadron-hadron interaction and its gluonic
  contribution

abstract:
  We propose a formalism for calculating the event cross-section of parton
interactions. In this formalism, we use the light-front bound-state wave
function to expand scattering initial state. This leads to an expression of the
cross-section in terms of square of wave functions which can be used to define
the parton distribution functions. The probability interpretation of the
partonic interactions among hadron-hadron scattering is naturally achieved. We
apply this formalism to calculate the 4-particle final state cross-section for
single parton, double parton and gluon splitting interactions. We compare the
behaviors of these cross sections and propose a method for experiments to
differentiate these interactions.


title:
Perturbative relations between $e^+e^-$ annihilation and $\tau$ decay
  observables including resummation effects

abstract:
  By exploiting the analyticity properties of the two-point current-current
correlator we obtain numerical predictions for the $e^+e^-$ moments in terms of
the $\tau$ decay rate. We perform a partial resummation of the pertinent
perturbative series expansion by solving the renormalization group equation for
Adler's function. Our predictions are renormalization scheme independent but
depend on the order of the perturbative $\beta$-function expansion. The
analysis involves the unknown five-loop coefficient $k_3$ for which we give
some new estimates.


title:
Deeply bound pionic states and the effective pion mass in nuclear
  systems

abstract:
  We show that the s-wave pion-nuclear potential which reproduces the deeply
bound pionic states in Pb, recently discovered at GSI, is remarkably close to
the one constructed directly from low energy theorems based on chiral symmetry.
Converting this information into an effective pion mass we find
$m_\pi^\star/m_\pi\simeq 1.13$ in the center of the Pb nucleus, and
$m_\pi^\star/m_\pi\simeq 1.07$ in symmetric nuclear matter.


title:
Current correlation functions, QCD sum rules and vector mesons in
  baryonic matter

abstract:
  Based on an effective Lagrangian which combines chiral SU(3) dynamics with
vector meson dominance, we have developed a model for the forward vector
meson-nucleon scattering amplitudes. We use this as an input to calculate the
low energy part of the current-current correlation function in nuclear matter.
Its spectrum enters directly in the ``left hand side'' of QCD sum rules. For
the isovector channel we find a significant enhancement of the in-medium
spectral density below the rho resonance while the rho meson mass itself
changes only slightly. The situation is different in the isoscalar channel,
where the mass and peak position of the omega meson move downward while its
width increases less drastically than in the rho meson case. For the phi meson
we find almost no mass shift; the width of the peak broadens moderately. We
observe a remarkable degree of consistency with the operator product expansion
of QCD sum rules in all three channels. We point out, however, that these
results cannot simply be interpreted, as commonly done, in terms of a universal
rescaling of vector meson masses in matter.


title: The Preheating - Gravitational Wave Correspondence

abstract:
  The gravitational wave equations form a parametric resonance system during
oscillatory reheating after inflation, when cast in terms of the electric and
magnetic parts of the Weyl tensor. This is in direct analogy with preheating.
For chaotic inflation with a quadratic potential, this analogy is exact. The
resulting amplification of the gravitational wave spectrum begins in the broad
resonance regime for chaotic inflation but quickly moves towards narrow
resonance. This increases the amplitude and breaks the scale invariance of the
tensor spectrum generated during inflation, an effect which may be detectable.
The parametric amplification is absent, however, in 1st-order phase transition
models and "warm" inflationary models with continuous entropy production.


title: Limits on Anomalous Top Couplings from Z Pole Physics

abstract:
  We obtain constraints on possible anomalous interactions of the top quark
with the electroweak vector bosons arising from the precision measurements at
the Z pole. In the framework of $SU(2)_L \otimes U(1)_Y$ chiral Lagrangians, we
examine all effective CP-conserving operators of dimension five which induce
fermionic currents involving the top quark. We constrain the magnitudes of
these anomalous interactions by evaluating their one-loop contributions to the
Z pole physics. Our analysis shows that the operators that contribute to the
LEP observables get bounds close to the theoretical expectation for their
anomalous couplings. We also show that those which break the $SU(2)_C$
custodial symmetry are more strongly bounded.


title: Physics of the W boson at future linear colliders

abstract:
  A survey is given of the various aspects of W-boson physics at the next
generation of linear colliders. In particular, it is indicated how the W boson
can help us improve our understanding of the mechanism of mass generation and
the structure of the non-abelian gauge-boson interactions. Also the topics of
radiative corrections and gauge invariance are briefly addressed.


title: CP violation in B decays and supersymmetry

abstract:
  CP violation in hadronic B-decays is studied in a definite and well motivated
framework of flavour physics and supersymmetry. Possible deviations from the
standard model both in mixing and in decay amplitudes are discussed. An attempt
is made to describe an experimental strategy for looking at these deviations
and for measuring the relevant parameters.


title: Relic Density of Neutralino Dark Matter in Supergravity Models

abstract:
  We calculate the relic density ($\Omega_{\chi^0_1} h^2$) of neutralino dark
matter in supergravity models with radiative electroweak symmetry breaking, for
values of the Higgs sector parameter $\tan\beta \equiv v_2/v_1$ between the two
infrared fixed points of the top quark Yukawa coupling, $\tan\beta \simeq 1.8$
and $\tan\beta \simeq 56$. For $\tan\beta \alt 10$, the CP-odd Higgs
pseudoscalar ($A^0$) and the heavier CP-even Higgs scalar ($H^0$) are much
heavier than the lightest neutralino ($\chi^0_1$), and the annihilation cross
section of $\chi^0_1$ pairs is significantly enhanced only in the vicinity of
the lighter CP-even Higgs boson ($h^0$) and the $Z$ boson poles. For $\tan\beta
\agt 40$, $m_A$ and $m_H$ become comparable to $2m_{\chi^0_1}$, and the
neutralino annihilation cross section can be significantly enhanced by the
poles of the $H^0$ and the $A^0$ as well. For a cosmologically interesting
relic density, $0.1 \alt \Omega_{\chi^0_1} h^2 \alt 0.5$, we find that the
supergravity parameter space is tightly constrained. The mass spectra for
supersymmetric particles are presented for unification mass parameters in the
cosmologically interesting region.


title:
Nonlinearities and Pomeron Nonfactorizability in Conventional
  Diffraction

abstract:
  Alternatives for describing the nonlinear behavior of the first diffraction
cone in differential $pp$ and $\bar pp$ elastic cross-section are investigated.
High quality fits to the data are presented. We show that the presence in the
Pomeron amplitude of two terms with different $t$ dependences is strongly
suggested by the data, hinting at a non-factorizable Pomeron even in the field
of purely hadronic reactions. The available data, however, do no allow to
choose among a nonlinearity in the residues or in the Pomeron trajectory or in
both. In all cases, we find an effective slope of the trajectory larger than
the one currently used. A nonlinear trajectory with the fitted parameters is
used for predicting the mass and the width of the 2$^{++}$ glueball. An
excellent agreement is found with the X(1900) candidate from the WA91
experiment.


title: Radiatively Corrected Semileptonic Spectra in B Meson Decays

abstract:
  We show how radiative QCD corrections calculated in terms of quarks can be
incorporated at the hadron level in inclusive semileptonic B-meson decays. The
bound state effects are described by a momentum distribution function of the
$b$ quark. The summation over the final states and the averaging over the
momentum distribution of the decaying quark render the radiative corrections
finite. With this coherent formalism we investigate the shape of the electron
spectra for $b\to u$ and $b\to c$ decays as a function of the parameters of the
theory. The resultant $b\to c$ electron energy spectrum is in agreement with
the experimental data.


title:
Restricted conformal invariance in QCD and its predictive power for
  virtual two-photon processes

abstract:
  The conformal algebra provides powerful constraints, which guarantee that
renormalized conformally covariant operators exist in the hypothetical
conformal limit of the theory, where the $\beta$-function vanishes. Thus, in
this limit also the conformally covariant operator product expansion on the
light cone holds true. This operator product expansion has predictive power for
two-photon processes in the generalized Bjorken region. Only the Wilson
coefficients and the anomalous dimensions that are known from deep inelastic
scattering are required for the prediction of all other two-photon processes in
terms of the process-dependent off-diagonal expectation values of conformal
operators. It is checked that the next-to-leading order calculations for the
flavour non-singlet meson transition form factors are consistent with the
corrections to the corresponding Wilson coefficients in deep inelasitic
scattering.


title: Isospin Mixing and Model Dependence

abstract:
  We show that recent calculations of \Delta I=3/2 effects in nonleptonic
hyperon decay induced by m_d-m_u\neq 0 are subject to significant model
dependence.


title: Colour-Dielectric Gauge Theory on a Transverse Lattice

abstract:
  We investigate in some detail consequences of the effective colour-dielectric
formulation of lattice gauge theory using the light-cone Hamiltonian formalism
with a transverse lattice. As a quantitative test of this approach, we have
performed extensive analytic and numerical calculations for 2+1-dimensional
pure gauge theory in the large N limit. Because of Eguchi-Kawai reduction, one
effectively studies a 1+1-dimensional gauge theory coupled to matter in the
adjoint representation. We study the structure of coupling constant space for
our effective potential by comparing with the physical results available from
conventional Euclidean lattice Monte Carlo simulations of this system. In
particular, we calculate and measure the scaling behaviour of the entire
low-lying glueball spectrum, glueball wavefunctions, string tension, asymptotic
density of states, and deconfining temperature. We employ a new hybrid
DLCQ/wavefunction basis in our calculations of the light-cone Hamiltonian
matrix elements, along with extrapolation in Tamm-Dancoff truncation,
significantly reducing numerical errors. Finally we discuss, in light of our
results, what further measurements and calculations could be made in order to
systematically remove lattice spacing dependence from our effective potential a
priori.


title: Could HERA results have been predicted from semileptonic meson decays

abstract:
  The anomalous value of the tensor form factor in the kaon decay K -> pi e nu
and the destructive interference in pion decay pi -> e nu gamma can be
simultaneously described by admixture of a tensor interaction in the standard
V-A one. It is shown that the same tensor interaction can describe recent HERA
data at very large Q^2.


title: LEP Limits on CP-Violating Non-Minimal Higgs Sectors

abstract:
  We derive a sum rule which shows how to extend LEP limits on the masses of
the lightest CP-even and CP-odd Higgs bosons of a CP-conserving
two-Higgs-doublet model to any two Higgs bosons of a general CP-violating
two-Higgs-doublet model. We generalize the analysis to a Higgs sector
consisting of an arbitrary number of Higgs doublets and singlets, giving
explicit limits for the CP-conserving and CP-violating two-doublet plus
one-singlet Higgs sectors.


title: Limits on R-parity violation from cosmic ray antiprotons

abstract:
  We constrain the hadronic R-parity violating couplings in extensions to the
minimal supersymmetric standard model. These interactions violate baryon and
lepton number, and allow the lightest superpartner (LSP) to decay into standard
model particles. The observed flux of cosmic ray antiprotons places a strong
bound on the lifetime of the LSP in models where the lifetime is longer than
the age of the universe. We exclude 10^-18<lambda''<10^-15 and
2x10^-18<lambda'<2x10^-15 except in the case of a top quark, where we can only
exclude 4x10^-19<lambda'<4x10^-16.


title: B -> K eta' decay as unique probe of eta' meson

abstract:
  A theory of the B -> K \eta' decay is proposed. It is based on the Cabbibo
favored b -> \bar{c} c s process followed by a direct materialization of the
\bar{c} c pair into the \eta'. This mechanism works due to a non-valence Zweig
rule violating c-quark component of the \eta', which is unique to its very
special nature. This non-perturbative "intrinsic charm" content of the \eta' is
evaluated using the Operator Product Expansion and QCD low energy theorems. Our
results are consistent with an unexpectedly large Br(B -> K \eta') \simeq 7.8
\cdot 10^{-5} recently announced by CLEO.


title:
The QCD corrections to scalar top pair production in photon-photon
  collisions

abstract:
  The complete QCD corrections to the scalar top quark pair production via
$\gamma \gamma$ fusion in parent $e^{+}e^{-}$ collider are calculated in the
Supersymmetric Model. The various origins of corrections are discussed. We find
that the correction due to gluino exchange is smaller than that due to
conventional gluonic contribution, and the contribution due to squark quartic
interactions is much smaller. Moreover, the dependences of the corrections on
the masses and the mixing angle of the supersymmetric particles are also
investigated.


title: Dilepton and Photon Emission Rates from a Hadronic Gas II

abstract:
  We extend our recent analysis of the dilepton and photon emission rates to
the case of finite temperature and baryon density, within the context of a
density expansion. To leading order, the effects of the baryon density are
assessed using data (photon emission) or constraints from broken chiral
symmetry (dilepton emission). Next to leading order effects are worked out, and
their contribution qualitatively assessed. The opening of the $\pi N$ cut
causes the photon rate to saturate the empirical photon yield of WA80, but may
not be enough to fully account for the excess low mass dileptons seen at CERES.


title:
Elastic pion-nucleon Scattering to O(p^3) in Heavy Baryon Chiral
  Perturbation Theory

abstract:
  The elastic pi-N scattering amplitude in the isospin limit is calculated in
the framework of heavy baryon chiral perturbation theory, up to the third
order. Threshold parameters like scattering lengths, volumes, effective ranges,
etc. are compared with data. All relevant low energy constants are fixed from
the available pion-nucleon data. A clear improvement in the description of data
is observed, when going from the first two orders in the chiral expansion to
the third one. The importance of even higher orders is suggested by the result.


title: 3d SU(N) + adjoint Higgs theory and finite temperature QCD

abstract:
  We study to what extent the three-dimensional SU(N)+adjoint Higgs theory can
be used as an effective theory for finite temperature SU(N) gauge theory, with
N=2,3. The parameters of the 3d theory are computed in 2-loop perturbation
theory in terms of T/Lambda_MSbar,N,N_f. The perturbative effective potential
of the 3d theory is computed to two loops for N=2. While the Z(N) symmetry
probably driving the 4d confinement-deconfinement phase transition (for N_f=0)
is not explicit in the effective Lagrangian, it is partly reinstated by
radiative effects in the 3d theory. Lattice simulations in the 3d theory are
carried out for N=2, and the static screening masses relevant for the
high-temperature phase of the 4d theory are measured. In particular, we measure
non-perturbatively the O(g^2 T) correction to the Debye screening mass. We find
that non-perturbative effects are much larger in the SU(2) + adjoint Higgs
theory than in the SU(2) + fundamental Higgs theory.


title:
Associated Production of $H^0\gamma$ or $H^0Z^0$ pairs at $\mu^+\mu^-$
  Collisions

abstract:
  We calculate the cross-sections for the production of Standard Model Higgs
Boson in association with the neutral gauge bosons (photon and Z--boson). For
the case of reaction $\mu^+ \mu^- \to \gamma H^0$, complete and compact
analytical expressions for the differential and total cross--sections,
applicable also for the case of any (pseudo)scalar particle with mass-coupling
proportionality, in particulary, for an axion are given. Reaction $\mu^+ \mu^-
\to Z^0 H^0$ is some "generalization" of the well-known "Bjorken process" for
the case of $ e^+ e^-$ collisions. Various distributions for both the processes
above are illustrated for the energies, which will be reached at future $\mu^+
\mu^-$ colliders. Study of those processes will be evidently complementary to
the precision measurements at the Higgs resonance region.


title: Measurement of CPT violation in the neutral kaon system

abstract:
  The basic feature of the measurement of CPT violation in the neutral kaon
system is overviewed beginning with noting the physical implication of CPT
violation. After describing $K^0-\bar{K}^0$ system at length, how CPT test is
possible is illustrated with adding a few remarks on it.


title: Determination of W-boson Properties at Hadron Colliders

abstract:
  Methods for measuring the W-boson properties at hadron colliders are
discussed. It is demonstrated that the ratio between the W- and Z-boson
observables can be reliably calculated using perturbative QCD, even when the
individual W- and Z-boson observables are not. Hence, by using a measured
Z-boson observable and the perturbative calculation of the ratio of the W- over
Z-boson observable, we can accurately predict the W-boson observable. The use
of the ratio reduces both the experimental and theoretical systematic
uncertainties substantially. Compared to the currently used methods it might,
at high luminosity, result in a smaller overall uncertainty on the measured
W-boson mass and width.


title:
Off-diagonal Helicity Density Matrix Elements for Vector Mesons Produced
  at LEP

abstract:
  Final state quark-antiquark interactions may give origin to non zero values
of the off-diagonal element rho_{1,-1} of the helicity density matrix of vector
mesons produced in e+e- annihilations, as confirmed by recent OPAL data on phi
and D^*'s. Predictions are given for rho_{1,-1} of several mesons produced at
large z and small p_T, i.e. collinear with the parent jet; the values obtained
for phi and D^* are in agreement with data.


title:
Long-distance contribution to exclusive rare decays of heavy mesons in
  quark model

abstract:
  Nonperturbative effects in exclusive reactions $B\to K^{(*)}ll$ are
discussed. Form factors which describe the main long-distance contribution to
the meson transition amplitude are calculated within the dispersion formulation
of the quark model: namely, the form factors in the decay region are expressed
as relativistic double spectral representations through the wave functions of
the initial and final mesons. The dilepton forward-backward asymmetry and the
lepton polarization turn out to be largely independent of the particular choice
of the quark model parameters and can be predicted with high accuracy. At the
same time, these asymmetries are sensitive to the short-distance structure of
the theory and might be used as a test of the Standard Model and probe of new
physics.


title: Hot Nucleons in Chiral Soliton Models

abstract:
  Chiral lagrangians as effective field theories of QCD are most suitable for
the study of nucleons in a hot pion gas because they contain pions and also
baryons as solitons of the same action. The semiclassical treatment of the
soliton solutions must be augmented by pionic fluctuations which requires
renormalisation to 1-loop, and finite temperatures do not introduce new
ultraviolet divergencies and may easily be considered. Alternatively, a
renormalisation scheme based on the renormalisation group equation at finite
temperature comprises and extends the rigorous results of chiral perturbation
theory and renders the low energy constants temperature-dependent which allows
the construction of temperature-dependent solitons below the critical
temperature. The temperature-dependence of the baryon energy and the
pion-nucleon coupling is studied. There is no simple scaling law for the
temperature-dependence of these quantities.


title:
Constraining the CKM angle $\gamma$ and penguin contributions through
  combined $B \to \pi K$ branching ratios

abstract:
  Motivated by recent CLEO measurements of $B\to\pi K$ modes, we investigate
their implications for the CKM angle $\gamma$ and a consistent description of
these decays within the Standard Model. Interestingly it turns out that already
the measurement of the combined branching ratios $B^\pm\to\pi^\pm K$ and
$B_d\to\pi^\mp K^\pm$ allows to derive stringent constraints on $\gamma$ which
are complementary to the presently allowed range for that angle. This range,
arising from the usual fits of the unitarity triangle, is typically symmetric
around $\gamma = 90^\circ$, while our method can in principle exclude a range
of this kind. Consistency within the Standard Model implies furthermore bounds
on the ratio $r\equiv|T'|/|\tilde P|$ of the current-current and penguin
operator contributions to $B_d\to\pi^\mp K^\pm$, and upper limits for the
CP-violating asymmetry arising in that decay. Commonly accepted means to
estimate $r$ yield values at the edge of compatibility with the present CLEO
measurements.


title:
Estimating the effects of Bose-Einstein correlations on the W mass
  measurement at LEP2

abstract:
  The influence of Bose-Einstein correlations on the determination of the mass
of the W boson in e+e- -> WW -> 4jet events at LEP2 energies is studied, using
a global event weighting method. We find that it is possible to keep the
systematic error on the W mass from this source below 20 MeV, if suitable
precautions are taken in the experimental analysis.


title: Gauge Invariant Effective Potentials and Higgs Mass Bounds

abstract:
  The problem of defining a gauge invariant effective potential with a strict
energetic interpretation is examined in the context of spontaneously broken
gauge theories. It is shown that such a potential can be defined in terms of a
composite gauge invariant order parameter in physical gauges. This effective
potential is computed through one loop order in a model with scalars and
fermions coupled to an abelian gauge theory, which serves as a simple model of
the situation in electroweak theory, where vacuum stability arguments based on
the scalar effective potential have been used to place lower bounds on the
Higgs mass.


title: Quenched Chiral Perturbation Theory for Heavy Baryons

abstract:
  Heavy baryon chiral perturbation theory is extended to include the effects of
quenching. In this framework the leading nonanalytic dependence of the heavy
baryon masses on the light quark masses is studied. The size of quenching
effects is estimated by comparing the results of quenched and ordinary chiral
perturbation theories. It is found that in general they can be large. This
estimate is relevant to lattice simulations of the heavy baryon masses.


title: On the Symmetry Constraints of CP Violations in QCD

abstract:
  Three symmetry constraints on the CP violations in QCD are discussed in this
paper. In order to generate CP violating observables from QCD, these
constraints require: (1) spontaneous chiral symmetry breaking, (2) explicit
chiral symmetry breaking, e.g., finite quark masses, (3) $U_A(1)$ anomaly, in
addition to a nonzero $\thetabar$ parameter. A pictorial illustration is used
to unify and elucidate these constraints and indicate a dual relation between
quark mass and the quark condensate. Based on the symmetry constraints, a
dynamical suppression scenario to solve the strong CP problem within QCD is
examined. We conclude that a solution of the strong CP problem has to involve
physics beyond the standard model.


title: Explaining the HERA Anomaly Without Giving Up R-parity Conservation

abstract:
  We point out that in extended supersymmetric models such as supersymmetric
left-right models, it is possible to have leptoquarks that explain the HERA
high $Q^2$ anomaly without giving up R-parity conservation. The leptoquarks
belong to vectorlike $(2, 2, \pm{4/3}, 3 or 3^*) $ representations of
$SU(2)_L\times SU(2)_R\times U(1)_{B-L}\times SU(3)_c$ (denoted $G_{2213}$).
Unlike the R-parity violating scenario, the leptoquarks are accompanied by new
superpartners,the leptoquarkino which leads to many intersting signatures in
other collider experiments. At Tevatron, pair productions of the leptoquarkino
will give rise to dilepton signals very distinct from the top productions.
These models can lead to unification of gauge coupling constants at a scale of
around $10^{10}$ GeV implying that grand unification group is not of the usual
SU(5) or SO(10) types but rather an automatically R-parity conserving
$SU(5)\times SU(5)$ GUT model recently proposed by one of the authors (R. N.
M.) which leads to a stable proton.


title: Comment on the $W + 1$ jet to $W + 0$ jets ratio

abstract:
  To offer a possible resolution to the apparent discrepancy between the
experimental and the theoretical values of the $W + 1$ jet to $W + 0$ jets
ratio reported by the \D0 group, we examine the effects of the multiple soft
gluon radiation on the $W$ boson production at the Tevatron. Based on the
calculation of the $W$ boson transverse momentum ($Q_T$) distribution in the
Collins-Soper-Sterman resummation formalism, we conclude that the effect of the
soft gluon radiation is important in the region of $Q_T < 50$ GeV, and it can
be better tested by a more inclusive observable $R_{CSS}(Q_T^{\min})\equiv
\frac{\sigma(Q_T>Q_T^{\min})}{\sigma _{Total}}$.


title: Mean-field transport theory for the two-flavour NJL model

abstract:
  By making decomposition of the Wigner function simultaneously in both the
spinor and the isospin spaces we derive a set of kinetic equations for the
quark distribution functions and the spin densities. A detailed analysis of the
consequences imposed by the chiral invariance on the form of the transport
equations is presented.


title: Can Cosmic Ray Catalysed Vacuum Decay Dominate Over Tunnelling?

abstract:
  We consider the question of whether cosmic ray catalysed false vacuum decay
can be phenomenologically more important than spontaneous decay via quantum
tunnelling. We extend the zero bubble wall width Landau-WKB analysis of
catalysed false vacuum decay to include the leading order effects of finite
wall width and derive an expression for the thin-wall bubble action. Using this
we calculate the exponential suppression factor for the catalysed decay rate at
the critical bubble energy, corresponding to the largest probability of
catalysed decay. We show that, in general, cosmic ray catalysed decay is likely
to be more important than spontaneous decay for sufficiently thin-walled
bubbles (wall thickness less than about 30 % of the initial bubble radius), but
that spontaneous decay will dominate for the case of thick-walled bubbles.
Since any perturbative model with a cosmologically significant false vacuum
decay rate will almost certainly produce thick-walled bubbles, we can conclude
that cosmic ray catalysed false vacuum decay will never dominate over
tunnelling in imposing phenomenological constraints on perturbative particle
physics models.


title: New Mass Relation for Meson 25-plet

abstract:
  By assuming the existence of (quasi)-linear Regge trajectories for 25-plet
mesons in the low energy region, we derive a new, 14th power, meson mass
relation. This relation may be reduced to a quadratic Gell-Mann-Okubo type
formula by fitting the values of the Regge slopes of these (quasi)-linear
trajectories. Such a formula holds with an accuracy of ~2% for vector mesons,
and also suggests that the quantum number I(J^P)=1/2(2^{+}) should be assigned
to the both B_J(5732) and B_{sJ}(5850) mesons discovered recently. We also
discuss reasons for the failure of group theory to produce correct mass
relations for heavy quarkonia.


title:
Interference of Charged Particles in a Vector Potential with Vanishing
  Magnetic Field

abstract:
  An interference experiment in a magnetic field free region with non vanishing
vector potential created by two perpendicularly intersecting planes carrying
uniform currents is discussed. The relation of this configuration to the
Aharonov-Bohm potential is examined. An experimental set up which is finite in
the direction of the electronic motion is studied.


title: Hybrid Decays

abstract:
  The heavy quark expansion of Quantum Chromodynamics and the strong coupling
flux tube picture of nonperturbative glue are employed to develop the
phenomenology of hybrid meson decays. The decay mechanism explicitly couples
gluonic degrees of freedom to the pair produced quarks and hence does not obey
the well known, but model-dependent, selection rule which states that hybrids
do not decay to pairs of L=0 mesons. However, the nonperturbative nature of
gluonic excitations in the flux tube picture leads to a new selection rule:
light hybrids do not decay to pairs of identical mesons. New features of the
model are highlighted and partial widths are presented for several low lying
hybrid states.


title:
Vacuum expectations of the high dimensional operator and their
  contribution in Bjorken and Ellis-Jaffe sum rules

abstract:
  The method of estimation of the unknown high-dimensional vacuum averages is
offered. This method is based on the idea of self-consistence of the
factorization hypothesis. So it appears possible to evaluate all vacuum
averages of dimension 7 and also get some estimations for vacuum averages of
dimension 10. Obtained results are used to calculate high dimensional operator
contribution to Bjorken and Ellis-Jaffe sum rules.


title: Higgs Decay to Top Quarks at O(\alpha_s^2)

abstract:
  Three-loop corrections to the scalar and pseudo-scalar current correlator are
calculated. By applying the large momentum expansion mass terms up to order
(m^2/q^2)^4 are evaluated analytically. As an application O(\alpha_s^2)
corrections to the decay of a scalar and pseudo-scalar Higgs boson into top
quarks are considered. It is shown that for a Higgs mass not far above the
$t\bar{t}$ threshold these higher order mass corrections are necessary to get
reliable results.


title: A Phenomenological Analysis of Non-resonant Charm Meson Decays

abstract:
  We analyse the consequences of the usual assumption of a constant function to
fit non-resonant decays from experimental Dalitz plot describing charmed meson
decays. We first show, using the $D^+\to \bar{K}^0\pi^+\pi^0$ decay channel as
an example, how an inadequate extraction of the non-resonant contribution could
yield incorrect measurements for the resonant channels. We analyse how the
correct study of this decay will provide a test for the validity of
factorization in D meson decays. Finally, we show how form factors could be
extracted from non-resonant decays. We particularly discuss about the form
factor that can be measured from the $D^+_s\to \pi^-\pi^+\pi^+$ decay. We
emphasize on its relevance for the study of the decay $\tau \to \nu_{\tau}
3\pi$ and the extraction of the $a_1$ meson width.


title: Fluctuations in Hadronic and Nuclear Collisions

abstract:
  We investigate several fluctuation effects in high-energy hadronic and
nuclear collisions through the analysis of different observables. To introduce
fluctuations in the initial stage of collisions, we use the Interacting Gluon
Model (IGM) modified by the inclusion of the impact parameter. The inelasticity
and leading-particle distributions follow directly from this model. The
fluctuation effects on rapidity distributions are then studied by using
Landau's Hydrodynamic Model in one dimension. To investigate further the
effects of the multiplicity fluctuation, we use the Longitudinal Phase-Space
Model, with the multiplicity distribution calculated within the hydrodynamic
model, and the initial conditions given by the IGM. Forward-backward
correlation is obtained in this way.


title: New (g-2)_{\mu} Constraints on Light-Gravitino Models

abstract:
  We show that the gravitino contribution to (g-2)_{\mu} is finite in many
popular supergravity models, including no-scale supergravity and string and
M-theory models. This contribution is greatly enhanced for very light gravitino
masses, and leads to new upper bounds on the ratio of the smuon to the
gravitino mass.


title: New Mass Relations for Heavy Quarkonia

abstract:
  By assuming the existence of (quasi)-linear Regge trajectories for heavy
quarkonia in the low energy region, we derive a new, sixth power, meson mass
relation which shows good agreement with experiment for both charmed and beauty
mesons. This relation may be reduced to a quadratic Gell-Mann-Okubo type
formula by fitting the values of the Regge slopes of these (quasi)-linear
trajectories. For charmed mesons, such a formula holds with an accuracy of
$\sim 1$%, and is in qualitative agreement with the relation obtained
previously by the application of the linear spectrum to a meson hexadecuplet.


title:
Generic consequences of a supersymmetric U(1) gauge factor at the TeV
  scale

abstract:
  We consider an arbitrary supersymmetric U(1) gauge factor at the TeV scale,
under which the two Higgs superfields H_{1,2} of the standard model are
nontrivial. We assume that there is a singlet superfield S such that H_1 H_2 S
is an allowed term in the superpotential. We discuss first the generic
consequences of this hypothesis on the structure of the two-doublet Higgs
sector at the electroweak energy scale, as well as Z-Z' mixing and the
neutralino sector. We then assume the existence of a grand unified symmetry and
universal soft supersymmetry breaking terms at that scale. We further assume
that the additional U(1) is broken radiatively via a superpotential term of the
form h h^c S, where h and h^c are exotic color-triplet fields which appear in
E_6 models. We show that the U(1) breaking scale and the parameter tan(beta)
\equiv v_2/v_1 are then both predicted as functions of the H_1 H_2 S coupling.


title: Constraints on the charged Higgs sector from the CDF Top quark data

abstract:
  The top quark data in the lepton plus $\tau$ channel offers a viable probe
for the charged Higgs boson signal. We have analysed the recent Collider
Detector at Fermilab (CDF) data in this channel to obtain a significant limit
on the $H^\pm$ mass in the large $\tan\beta$ region.


title:
BHAGEN95: a Monte Carlo program for Bhabha scattering at LEP1/SLC and
  LEP2 energies

abstract:
  We present the Monte Carlo program BHAGEN95, for calculating the
cross-section of the Bhabha scattering process at LEP1/SLC and LEP2 energies,
usable with continuity from small to large-angle configurations. We discuss
some improvements in the event generator BHAGEN94, which is now part of the new
code. In particular the weak and QCD corrections are implemented up to two
loops for the relevant contributions, and the emission of one hard photon is
treated exactly. We have included all the radiative corrections which are
necessary to obtain, for a typical experimental event selection, a precision of
0.1-0.2% at small-angle. At large-angle we estimate a precision of 0.5%, with
the exception of the region where the beam energy is a few GeV above the Z
boson resonance, where it is up to 1%. A detailed comparison with other codes
for both small-angle and large-angle Bhabha scattering is performed.


title:
Constraints on the mass of the superlight gravitino from the muon
  anomaly

abstract:
  We reexamine the limits on the gravitino mass supplied by the muon anomaly in
the frame of supergravity models with a superlight gravitino and a superlight
scalar S and a superlight pseudoscalar P.


title: Inclusive Charmed-Baryon Decays and Lifetimes

abstract:
  We have quantitatively reanalyzed the inclusive charmed-baryon decays. New
ingredients are the Voloshin preasymptotic effects in semileptonic decays and
the Cabibbo-subleading contributions to both semileptonic and nonleptonic
decays. It has been found that the Cabbibo-subleading Voloshin contribution
essentially improves the theoretical semileptonic branching ratio of
$\Lambda_c^{+}$, in agreement with experiment. The semileptonic branching
ratios for $\Xi_c^{+}$ and $\Omega_c^{0}$ are found to be large, i.e., of the
order of 20%. The lifetimes hierarchy is in a good qualitative and even
quantitative agreement with experiment except for the $\Xi_c^{+}$ lifetime,
which is somewhat smaller than the experimental value. Future measurements,
especially measurements of the semileptonic branching ratios for
$\Omega_c^{0}$, $\Xi_c^{+}$ and $\Xi_c^{0}$ should be decisive for the check of
this approach.


title: Fine-tuning the low-energy physics

abstract:
  In this article we discuss the problem of the extreme fine-tuning necessary
to achieve the top quark mass scale $m_t$ within the dynamical symmetry
breaking of the phenomenological $t \bar t$ condensate model. Inspired by the
vector-like phenomenon of chiral gauge theories at short distances, we
postulate that the $W^\pm$-gauge bosons possess a vector-like gauge coupling
and contribute to the gap-equations of quark self-energy functions in the
high-energy region. We find that the gap-equations of different charge sectors
are coupled, and as a result the unnatural fine-tuning is overcome and the
ratio of the top and bottom masses is related to the electric charge:
$({m_b\over m_t})^2\simeq {\alpha\over3\pi}$, provided the quadratic divergence
is removed by setting the four-fermion coupling $G=4+o({m_b^2\over m_t^2})$.


title: Quarks and Gluon Fragmentation Functions into Photons

abstract:
  The fragmentation functions of quarks and gluons into photons are studied
beyond the Leading Logarithm approximation. We address the nature of the
initial conditions of the evolution equation solutions and study problems
related to factorization scheme invariance. The possibility of measuring these
distributions in LEP experiments is discussed, and a comparison with existing
data is made.


title:
HDECAY: a Program for Higgs Boson Decays in the Standard Model and its
  Supersymmetric Extension

abstract:
  We describe the Fortran code HDECAY which calculates the decay widths and the
branching ratios of the Standard Model Higgs boson, and of the neutral and
charged Higgs particles of the Minimal Supersymmetric extension of the Standard
Model. The program is self-contained (with all subroutines included), easy to
run, fast and calculates the decay widths and branching ratios according to the
current theoretical knowledge.


title: Physics of Heavy Ions Collisions: The Summary of Moriond-97

abstract:
  CERN dilepton experiments have provided the most exciting data. Strong
enhancement at low masses observed by CERES and HELIOS3 indicate strong
modification in the vector channel in matter compared to vacuum properties.
NA50 data on $J/\psi$ suppression in PbPb collisions show surprising deviation
from the previous trend. The question is whether it is the expected early-time
signal of QGP, or due to late-time hadronic interactions.
  Theoretical and experimental suggestions have been made to resolve this
issue. BNL and SPS experiments have also provided rather complete data with
heavy beams (Au and Pb, respectively). Very strong collective flow effects have
been observed at both energies, which allow for the first time to restrict the
EOS of the hadronic matter. Several observables (flow, Coulomb effects and HBT)
suggest rather long evolution of systems created in heavy ion collisions and
very low freeze-out densities relative to previous studies. Theory of jet
stopping in QGP is becoming quantitative.


title: Recognizing Superpartners at LEP

abstract:
  There is a class of supersymmetric models which is well-motivated by hints of
evidence for SUSY and consistent with all existing data. It is important to
study the predictions of these models. They are characterized by M(N3) > M(C1)
> M(snu) > M(N1) (where Ni and Ci are neutralino and chargino mass
eigenstates), |mu| ~< M1 ~< M2 ~= M(Z), mu < 0, and tan(beta) near 1. Their LEP
signatures are mostly unusual. Most produced superpartners are invisible! A
good signature is two photons plus large missing energy. There are also excess
events at large recoil mass in the single photon plus nothing channel. We list
the main signatures for charginos, stops, etc., which are also likely to be
unconventional. This class of models will be definitively tested at LEP194 with
100 pb^{-1} per detector, and almost definitively tested at LEP184.


title:
The QCD Phase Transition: From the Microscopic Mechanism to Signals Talk
  at Renconres de Moriond - 97

abstract:
  This talk consists of two very different parts: the first one deals with
non-perturbative QCD and physics of the chiral restoration, the second with
rather low-key (and still unfinished) work aiming at obtaining EOS and other
properties of hot/dense hadronic matter from data on heavy ion collisions. The
microscopic mechanism for chiral restoration phase transition is a transition
from randomly placed tunneling events (instantons) at low T to a set of
strongly correlated tunneling-anti-tunneling events (known as instanton -
anti-instanton molecules) at high T. Many features of the transition can be
explained in this simple picture, especially the critical line and its
dependence on quark masses. This scenario predicts qualitative change of the
basic quark-quark interactions around the phase transition line, with some
states (such as pion-sigma ones) probably surviving even at $T>T_c$. In the
second half of the talk we discuss experimental data on collective flow in
heavy ion collision, its hydro-based description and relation to equation of
state (EOS). A distinct feature of the QCD phase transition region is high
degree of ``softness'', (small ratio pressure/energy density).
  We present some preliminary results indicated that it is indeed needed to
explain the radial flow at SPS energies.


title: Towards the Theory of Reheating After Inflation

abstract:
  Reheating after inflation occurs due to particle production by the
oscillating inflaton field. In this paper we describe the perturbative approach
to reheating, and then concentrate on effects beyond the perturbation theory.
They are related to the stage of parametric resonance called preheating. It may
occur in an expanding universe if the initial amplitude of oscillations of the
inflaton field is large enough. We investigate a simple model of a massive
inflaton field coupled to another scalar field X. Parametric resonance in this
model is very broad. It occurs in a very unusual stochastic manner, which is
different from the parametric resonance in the case when the expansion of the
universe is neglected. Quantum fields interacting with the oscillating inflaton
field experience a series of kicks which occur with phases uncorrelated to each
other. We call this process stochastic resonance. We develop the theory of
preheating taking into account the expansion of the universe and backreaction
of produced particles, including the effects of rescattering. The process of
preheating can be divided into several distinct stages. At the first stage the
backreaction of created particles is not important. At the second stage
backreaction increases the frequency of oscillations of the inflaton field,
which makes the process even more efficient than before. Then the effects
related to scattering of X-particles terminate the resonance. We calculate the
density of X-particles and their quantum fluctuations with all backreaction
effects taken into account. This allows us to find the range of masses and
coupling constants for which one has efficient preheating. In particular, under
certain conditions this process may produce particles with a mass much greater
than the mass of the inflaton field.


title: Tau Physics

abstract:
  The pure leptonic or semileptonic character of tau decays makes them a good
laboratory to test the structure of the weak currents and the universality of
their couplings to the gauge bosons. The hadronic tau decay modes constitute an
ideal tool for studying low-energy effects of the strong interactions in very
clean conditions; a well-known example is the precise determination of the QCD
coupling from tau-decay data. New physics phenomena, such as a non-zero
tau-neutrino mass or violations of (flavour / CP) conservation laws can also be
searched for with tau decays.


title:
Comments on the Erhan-Schlein model of damping the pomeron flux at small
  x-pomeron

abstract:
  We explore the theoretical and experimental consequences of a model proposed
by Samim Erhan and Peter Schlein for unitarizing the diffractive amplitude by
damping the pomeron flux at small x-pomeron and conclude that the model is
unphysical and contradicts well established experimental data.


title: Finding Low-Scale Technicolor at Hadron Colliders

abstract:
  In multiscale and topcolor-assisted models of walking technicolor, relatively
light spin-one technihadrons $\rho_T$ and $\omega_T$ exist and are expected to
decay as $\rho_T \to W \pi_T, Z \pi_T$ and $\omega_T \to \gamma \pi_T$. For
$M_{\rho_T} \simeq 200 GeV$ and $M_{\pi_T} \simeq 100 GeV$, these processes
have cross sections in the picobarn range in $\bar p p$ colisions at the
Tevatron and about 10 times larger at the Large Hadron Collider. We demonstrate
their detectability with simulations appropriate to Run II conditions at the
Tevatron.


title:
Event-by-event analysis of heavy ion collisions and thermodynamical
  fluctuations

abstract:
  The event-by-event analysis of heavy ions collisions is becoming possible
with advent of large acceptance detectors: it can provide dynamical information
which cannot be obtained from inclusive spectra. We identify some observables
which can be related to standard thermodynamical fluctuations and therefore may
provide information about properties of hadronic matter at the freeze-out
stage. Among those are fluctuations of ``apparent temperature'' (the $p_t$
slope), as well as the population of different bins of the pion momentum
distribution.


title: Collider Phenomenology for Supersymmetry at Large $tan\beta$

abstract:
  If the parameter $tan \beta$ of the minimal supersymmetric model is large,
then $b$ and $\tau$ Yukawa interactions are important. These can significantly
modify the masses and decays of sparticles. We describe new calculations which
allow a reliable exploration of large $tan \beta$ values, and discuss
implications for collider experiments. For large values of $tan \beta$,
charginos and neutralinos may dominantly decay to $\tau$-leptons or $b$-quarks.
The usual cross sections for multilepton signatures may be greatly reduced, but
SUSY may be detectable via new signals involving $\tau$'s or $b$'s in the final
state.


title:
Supersymmetric Electroweak Phase Transition: Dimensional Reduction
  versus Effective Potential

abstract:
  We compare two methods of analyzing the finite-temperature electroweak phase
transition in the minimal supersymmetric standard model: the traditional
effective potential (EP) approach, and the more recently advocated procedure of
dimensional reduction (DR). The latter tries to avoid the infrared
instabilities of the former by matching the full theory to an effective theory
that has been studied on the lattice. We point out a limitation of DR that
caused a large apparent disagreement with the effective potential results in
our previous work. We also incorporate wave function renormalization into the
EP, which is shown to decrease the strength of the phase transition. In the
regions of parameter space where both methods are expected to be valid, they
give similar results, except that the EP is significantly more restrictive than
DR for the range of baryogenesis-allowed values of $\tan\beta$, $m_h$, the
critical temperature, and the up-squark mass parameter $m_U$. In contrast, the
DR results are consistent with $2\lsim\tan\beta\lsim 4$, $m_h<80$ GeV, and
$m_U$ sufficiently large to have universality of the squark soft-breaking
masses at the GUT scale, in a small region of parameter space. We suggest that
the differences between DR and EP are due to higher-order perturbative
corrections rather than infrared effects.


title: Phenomenology of 3-Family Grand Unified String Models

abstract:
  In the 3-family grand unified string models constructed so far, there is only
one adjoint (and no higher dimensional representation) Higgs field in the grand
unified gauge group. In this preliminary analysis, we address the proton-decay
problem in the 3-family E_6 and related SO(10) string models. In particular, we
analyze the doublet-triplet splitting (within certain assumptions about
non-perturbative dynamics). It appears that generically some fine-tuning is
necessary to arrange for a pair of Higgs doublets to be light, while having
color Higgs triplets superheavy. We also discuss charge-2/3 quark mass matrix
that generically also seems to require some fine-tuning to have rank 1.


title:
Flavor nonconservation and CP violation from quark mixings with singlet
  quarks

abstract:
  Flavor nonconserving and CP violating effects of the quark mixings are
investigated in electroweak models incorporating singlet quarks. Especially,
the D^0 - {\bar D}^0 mixing and the neutron electric dipole moment, which are
mediated by the up-type quark couplings to the neutral Higgs fields, are
examined in detail for reasonable ranges of the quark mixings and the singlet
Higgs mass scale. These neutral Higgs contributions are found to be comparable
to or smaller than the experimental bounds even for the case where the singlet
Higgs mass scale is of the order of the electroweak scale and a significant
mixing is present between the top quark and the singlet quarks.


title: Could Electromagnetic Corrections Solve The Vorton Excess Problem ?

abstract:
  The modifications of circular cosmic string loop dynamics due to the
electromagnetic self-interaction are calculated and shown to reduce the
available phase space for reaching classical vorton states, thereby decreasing
their remnant abundance. Use is made of the duality between master-function and
Lagrangian formalisms on an explicit model.


title: Hard inclusive production and a violation of the factorization theorem

abstract:
  A new mechanism for hard inclusive production, which leads to a violation of
the factorization theorem, is suggested. The mechanism is illustrated by a
detailed discussion of Higgs meson production in high energy deutron-deutron
scattering. Numerical estimates for the effect are given for high energy hadron
(nucleus) scattering.


title:
Infra-Red Stable Fixed Points of Yukawa Couplings in Supersymmetric
  Models

abstract:
  We provide the solutions of the fixed point conditions of the Yukawa sector
for a large class of N=1 supersymmetric theories including the minimal and
next-to-minimal supersymmetric standard models and their grand unified and
other extensions. We also introduce a test which can discriminate between
infra-red stable, infra-red unstable and saddle point solutions, and illustrate
our methods with the example of the next-to-minimal supersymmetric standard
model. We show that in this case, the fixed point prediction of the top quark
mass is equivalent to that of the minimal supersymmetric standard model,
supporting previous numerical analyses.


title: Comparion of Lattice and Dual QCD Results for Heavy Quark Potentials

abstract:
  Lattice results and Dual QCD results for all heavy quark potentials through
order (quark mass)^${-2}$ are exhibited and compared. The agreement on the
whole is quite good, confirming the validity of Dual QCD. NOTE: (The only
important change in this replaced version is that Figure 6 has been replotted,
because the lattice data used in the original was in the wrong units.)


title:
CP Violation vs. Matter Effect in Long-Baseline Neutrino Oscillation
  Experiments

abstract:
  We investigate, within the framework of three generations of neutrinos, the
effects of CP violation in long-baseline neutrino oscillation experiments. We
aim at illuminating the global feature of the interplay between genuine effect
due to the CP violating phase and a fake one due to the earth matter effect. To
this goal, we develop a formalism based on the adiabatic approximation and
perturbative treatment of the matter effect which allows us to obtain
approximate analytic expressions of the oscillation probabilities. We present
an order-of-magnitude estimation and a detailed numerical computation of the
absolute and the relative magnitudes of the CP violations under the mass
hierarchy suggested by the atmospheric neutrino anomaly and the cosmological
dark matter. We find that the genuine CP violating effect is at most \sim 1%,
and the matter effect dominates over the intrinsic CP violation only in a
region of parameters where the oscillation probability of $\nu_\mu\to\nu_e$ is
large.


title: $b \to s\ell^+\ell^-$ in the Left-Right Symmetric Model

abstract:
  We begin to analyze and contrast the predictions for the decay $b\to
s\ell^+\ell^-$ in the Left-Right Symmetric Model(LRM) with those of the
Standard Model(SM). In particular, we show that the forward-backward asymmetry
of the lepton spectrum can be used to distinguish the SM from the simplest
manifestation of the LRM. [To appear in the Proceedings of the 2nd
International Conference on B Physics and CP Violation, Honolulu, HI, 24-27
March 1997]


title: Large Top Quark Yukawa Coupling and Horizontal Symmetries

abstract:
  We consider the maximal U(3) horizontal scheme as a handle on fermion masses
and mixings. In particular, we attempt to explain the large top Yukawa coupling
and the masses and mixing in the two heaviest generations. A simple model is
constructed by enlarging the matter content of the Standard Model with that of
a $10+\bar{10}$ pair of SU(5). The third generation particles get their masses
when U(3) is broken to U(2). Top quark mass is naturally of order one. Bottom
and tau masses are suppressed because of a hierarchy in the effective Yukawa
couplings and not from the hierarchy in the Higgs doublet vacuum expectation
values. The hierarchy is a consequence of the fact that the particle spectrum
contains an incomplete vector-like generation and can come from hierarchies
between scales of breaking of different grand unified groups. Hierarchies and
mixings between the second and third generation are obtained by introducing a
single parameter epsilon' representing the breaking U(2) -> U(1). As a
consequence, we show that the successful (and previosuly obtained) relations
V_{cb} \approx (m_s / m_b) \approx \sqrt (m_c / m_t) easily follow from our
scheme.


title: Introduction to Gauge Theories

abstract:
  These lectures present an elementary introduction to quantum gauge fields.
The first aim is to show how, in the tree approximation, gauge invariance
follows from covariance and unitarity. This leads to the standard construction
of the Lagrangian by means of covariant derivatives in a form that unifies the
massive and the massless case. Having so identified the classical theory, the
Faddeev-Popov quantization method is introduced and the BRS invariance of the
resulting action is discussed.


title: Cosmological implications of a class of SO(10) models

abstract:
  The cosmological implications of a class of SO(10) models are discussed. In
particular we show how a good prediction for neutrino masses is obtained in
order to fit with the MSW mechanism to explain the solar neutrino flux deficit
and with the predicted amount of the dark matter hot component. A possible
scenario for baryogenesis is also considered.


title: Neutrino masses and baryogenesis in SO(10) unified theories

abstract:
  We report on some phenomenological implications of a class of unified models
based on SO(10) gauge group, with intermediate symmetry group containing
SU(2)_R. Interesting predictions for neutrino masses are discussed, which are
relevant both for solar neutrino and dark matter problems, as well as a model
for the formation of the baryon asymmetry of the universe required by
primordial nucleosynthesis.


title: Right-Handed b to c and u Coupling Model and CP Violation

abstract:
  We investigate CP violation in the purely right-handed b quark to c- and u-
quark coupling model under the constraint of right-handed W-gauge boson mass
M_R > 720 GeV , which is experimentally obtained recently by D0 Collaboration
at Fermilab. By using the data on $K_L-K_S$ mass difference, CP violating
parameter $\epsilon$ in the neutral kaon system and $B_d-\bar B_d$ mixing,
together with the new data of $Br (B^-\to \psi\pi^-) /Br (B^-\to \psi K^-) =
0.052 \pm 0.024 (\approx \mid V_{cd}/V_{cs} \mid^2)$, we can fix all of the
three independent angles and one phase of the right-handed mixing matrix V^R.
Under these constraints, another CP-violating parameter $\epsilon'/\epsilon$
and electric dipole moment of neutron are shown to be consistent with the data
in our model. The pattern of CP violation in the nonleptonic decay of
$B_d(B_s)$ mesons to CP eigenstates is different from that in the Standard
Model.


title:
CP-Violating Correlations between Lepton-Charge and Jet-Charge in Z ->
  b\bar b events

abstract:
  Correlations that signal direct CP violation in the bottom sector are
suggested. They need data on $Z\to b\bar b$ events which consist of a bottom
hadron decay into an exclusive semileptonic channel $h \ell \nu $ (where $h$ is
a hadron), and the other bottom hadron decay into a multi-body final state that
manifests as a jet in the opposite hemisphere.


title: Wave function renormalization in heavy baryon chiral perturbation theory

abstract:
  We establish exact relations between relativistic form factors and amplitudes
for single-baryon processes and the corresponding quantities calculated in the
framework of heavy baryon chiral perturbation theory. A crucial ingredient for
the proper matching is the first complete treatment of baryon wave function
renormalization in heavy baryon chiral perturbation theory.


title: Hadronization in Z0 decay

abstract:
  The confinement transition from the quark and gluon degrees of freedom
appropriate in perturbation theory to the hadrons observed by real world
experiments is poorly understood. In this strongly interacting transition
regime we presently rely on models, which to varying degrees reflect possible
scenarios for the QCD dynamics. Because of the absence of beam and target
remnants, and the clean experimental conditions and high event rates, e+e-
annihilation to hadrons at the Z0 provides a unique laboratory, both
experimentally and theoretically, for the study of parton hadronization. This
review discusses current theoretical understanding of the hadronization of
partons, with particular emphasis on models of the non-perturbative phase, as
implemented in Monte Carlo simulation programs. Experimental results at LEP and
SLC are summarised and considered in the light of the models. Suggestions are
given for further measurements which could help to produce more progress in
understanding hadronization.


title: Next-to-leading order corrections to e^+ e^- \to four jets

abstract:
  I present a general purpose Monte Carlo program for calculating the
next-to-leading order corrections to arbitrary four-jet quantities in
electron-positron annihilation. In the current version of the program, some
subleading in color terms are neglected. As an example, I calculate the
four-jet rate in the Durham scheme as well as the Bengtsson-Zerwas angular
distribution at $O(\alpha_s^3)$ and compare the results to existing data.


title:
Non-1/m_b^n Power Suppressed Contributions to Inclusive b->s l+ l-
  Decays

abstract:
  We compute non-perturbative contributions to b->s l+ l- that are not
explicitly suppressed by powers of the b-quark mass. They are proportional to
lambda_2 and arise from an interference between the free-quark amplitude and
higher order terms in the matrix element of a four-quark operator. This
correction is found to be small over most of the dalitz plot except near the
charm threshold. Unfortunately, the perturbative computation we have performed
is invalid near charm threshold and we do not except to see the structure found
at lowest order reproduced in the data. We conclude that these non-perturbative
contributions do not significantly modify the previous analysis of b->s l+ l-.


title:
Suppression of Heavy Ion gamma gamma Production of the Higgs by Coulomb
  Dissociation

abstract:
  Predicted two-photon Higgs production with heavy ions at LHC is shown to be
reduced due to the large Coulomb dissociation cross section. Incorporating the
effect of dissociation reduces the production of a 100 GeV Higgs by about a
factor of three compared to rates in the literature calculated without this
effect.


title: Optimal Renormalization Scale and Scheme for Exclusive Processes

abstract:
  We use the BLM method to fix the renormalization scale of the QCD coupling in
exclusive hadronic amplitudes such as the pion form factor and the
photon-to-pion transition form factor at large momentum transfer.
Renormalization-scheme-independent commensurate scale relations are established
which connect the hard scattering subprocess amplitudes that control exclusive
processes to other QCD observables such as the heavy quark potential and the
electron-positron annihilation cross section. The commensurate scale relation
connecting the heavy quark potential, as determined from lattice gauge theory,
to the photon-to-pion transition form factor is in excellent agreement with
$\gamma e \to \pi^0 e$ data assuming that the pion distribution amplitude is
close to its asymptotic form $\sqrt{3}f_\pi x(1-x)$. We also reproduce the
scaling and normalization of the $\gamma \gamma \to \pi^+ \pi^-$ data at large
momentum transfer. Because the renormalization scale is small, we argue that
the effective coupling is nearly constant, thus accounting for the nominal
scaling behavior of the data. However, the normalization of the space-like pion
form factor $F_\pi(Q^2)$ obtained from electroproduction experiments is
somewhat higher than that predicted by the corresponding commensurate scale
relation. This discrepancy may be due to systematic errors introduced by the
extrapolation of the $\gamma^* p \to \pi^+ n$ electroproduction data to the
pion pole.


title:
Two Higgs Doublet Model and Lepton Polarization in the B -> K tau+ tau-
  Decay

abstract:
  The decay width, forward-backward asymmetry and tau lepton longitudinal and
transversal polarization for the exclusive (B -> K tau^+ tau^-) decay in a two
Higgs doublet model are computed. It is shown that the forward-backward
asymmetry and longitudinal polarization of the tau lepton are very effective
tools for establishing new physics.


title:
Decay Widths of Excited Heavy Mesons From QCD Sum Rules at the Leading
  Order of HQET

abstract:
  The widths for pionic decays of lowest two excited doublets (0^+,1^+) and
(1^+,2^+) of heavy mesons are studied with QCD sum rules in the leading order
of heavy quark effective theory. The ambiguity due to presence of two distinct
1^+ states are solved. The soft pion approximation is not used.


title: Mesons a in Collinear QCD Model

abstract:
  A phenomenological model for the quark structure of mesons is considered. The
model is based on the tube model for QCD, where all quanta with nonzero
transverse momenta are neglected. In the limit that the mass term of the gluons
goes to infinity, the model is equivalent to a combination of the 't Hooft and
Gross-Neveu models and can be solved semi-analytically. The model has the
properties of confinement, chiral symmetry breaking and asymptotic freedom and
thus resembles QCD in three key respects. Spectra, distribution amplitudes and
form factors of mesons are analyzed.


title: Light-Front QCD and Heavy Quark Systems

abstract:
  In this series of lectures, I shall begin with the current investigations on
phenomenology of hadron dynamics to demonstrate the importance of solving
hadronic bound states within the framework of light-front (LF) QCD. Then, I
will describe the basic procedure how to formulate the canonical theory of
LFQCD, including light-front quantization of QCD, light-front gauge
singularity, and light-front two-component formalism. I will also present a
complete one-loop QCD calculation in terms of the light-front time-ordering
perturbation theory, in comparison with the usual covariant perturbative QCD
calculation. Following thereby I will discuss the development of heavy-quark
effective theory and the manifestation of heavy quark symmetry on the
light-front. Finally, by applying recently developed similarity renormalization
group approach to light-front heavy quark effective theory, I will show a
rigorous derivation of quark confinement interaction from LFQCD and its
application to solve heavy hadron bound states.


title:
A Weak-Coupling Treatment of Nonperturbative QCD Dynamics to Heavy
  Hadrons

abstract:
  Based on the recently developed light-front similarity renormalization group
approach and the light-front heavy quark effective theory, we derive
analytically from first-principles QCD a heavy quark light-front Hamiltonian
which contains explicitly a confinement interaction at long distances and a
Coulomb-type interaction at short distances. With this light-front QCD
Hamiltonian, we further demonstrate that the nonperturbative QCD dynamics of
the strongly interacting heavy hadron bound states can be treated as a
weak-coupling problem.


title: Tests of Basic Quantum Mechanics in Oscillation Experiments

abstract:
  According to standard quantum theory, the time evolution operator of a
quantum system is independent of the state of the system. One can, however,
consider systems in which this is not the case: the evolution operator may
depend on the density operator itself. The presence of such modifications of
quantum theory can be tested in long baseline oscillation experiments.


title: Direct-Transmission Models of Dynamical Supersymmetry Breaking

abstract:
  We systematically construct gauge-mediated supersymmetry(SUSY)-breaking
models with direct transmission of SUSY-breaking effects to the standard-model
sector. We obtain a natural model with the gravitino mass $m_{3/2}$ smaller
than 1 keV as required from the standard cosmology. If all Yukawa coupling
constants are of order one,the SUSY-breaking scale $m_{SUSY}$ transmitted into
the standard-model sector is given by $m_{SUSY} \simeq 0.1 \alpha_i/(4\pi)
\Lambda$ where $\Lambda$ is the original dynamical SUSY-breaking scale.
Imposing $m_{SUSY} \simeq (10^2-10^3)$ GeV, we get $\Lambda \simeq (10^5-10^6)$
GeV, which yields the gravitino mass $m_{3/2}\simeq (10^{-2}-1)$ keV.


title: Hadronic Antenna Patterns as a Probe of Leptoquark Production at HERA

abstract:
  Hadronic antenna patterns can provide a valuable diagnostic tool for probing
the origin of the apparent excess of high $x,Q^2$ events at HERA. We present
quantitative predictions for the distributions of soft particles and jets in
standard deep inelastic scattering $eq \to eq$ events and in events
corresponding to the production of a narrow colour-triplet scalar
(`leptoquark') resonance. The corresponding distributions of soft photon
radiation, which are sensitive to the leptoquark electric charge, are also
presented. The distribution for one particular leptoquark assignment is shown
to contain a radiation zero.


title:
Structure of f0(980) from a Coupled Channel Analysis of S-wave pi pi
  Scattering

abstract:
  A coupled channel model is used to study the nature of the f0(980) resonance.
It is shown that the existence of two poles close to KKbar threshold, as found
in many data fits and confirmed here, can be reconciled with the KKbar
molecular origin of the f0(980). Due to a strong coupling between channels the
number of the S-matrix poles close to the physical region in the physical case
exceeds the number of bare states introduced in the model.


title: CP Violation from the Neutrino Sector: A Case for the Superweak Model

abstract:
  We discuss how CP violation originating in the right-handed neutrino sector
can feed into the quark sector, in an otherwise CP invariant theory. The
dominant effects are superweak, and we suggest that this may yield a natural
resolution of the strong CP problem. This work builds on and extends a
previously proposed model of quark and lepton masses, based on a new strong
flavor interaction above the weak scale.


title: Neutrinos in Strong Magnetic Fields

abstract:
  We compute the dispersion curves for neutrinos propagating in an extremely
dense electroweak plasma, in the presence of very strong magnetic fields of
order $B \le M_W^2/e$. The neutrino self-energy is calculated in the one-loop
approximation. We consider only contributions of the first Landau level to the
propagator of the W-bosons, and distinguish between motion parallel or
perpendicular to the external magnetic field. We find that the neutrino
dispersion curve for parallel propagation to the field suggests a superfluid
behavior. An interesting analogy with fractional QHE is pointed out. We obtain
a neutrino effective mass which increases with the magnetic field.


title: Angular ordering and small-x structure functions

abstract:
  This talks examines the effect of angular ordering on the small-x evolution
of the unintegrated gluon distribution, and discusses the characteristic
function for the CCFM equation.


title: Resummation for QCD Hard Scattering

abstract:
  We resum distributions that are singular at partonic threshold (the elastic
limit) in heavy quark production, in terms of logarithmic behavior in moment
space. The method may be applied to a variety of cross sections sensitive to
the edge of phase space, including transverse momentum distributions. Beyond
leading logarithm, dependence on the moment variable is controlled by a matrix
renormalization group equation, reflecting the evolution of composite operators
that represent the color structure of the underlying hard scattering. At
next-to-leading logarithmic accuracy, these evolution equations may be
diagonalized, and moment dependence in the cross section is a sum of
exponentials. Beyond next-to-leading logarithm, resummation involves
matrix-ordering. We give a detailed analysis for the case of heavy quark
production by light quark annihilation and gluon fusion.


title: V_{ub} from the Hadronic Invariant Mass Spectrum in Semileptonic B Decay

abstract:
  The hadronic invariant mass spectrum for the inclusive charmless semileptonic
decay $B\to X_u e \bar\nu_e$ is studied. Particular attention is paid to the
region $s_H<m_D^2$, which may be useful for extracting the value of $|V_{ub}|$.
The sensitivity of the spectrum to the parameter $\bar\Lambda \equiv m_B - m_b$
is explored. Perturbative QCD corrections to $d\Gamma/ds_H$ of order
$\alpha_s^2\beta_0$ are calculated. For $s_H \sim \bar\Lambda m_b$
nonperturbative QCD effects are important and the shape of the invariant mass
spectrum is controlled by the B meson matrix element of an infinite sum of
local operators. The utility of the hadronic mass spectrum for extracting
$|V_{ub}|$ is explored.


title:
Contact Interaction Explanation of HERA Events and $SU(3)_C\times
  SU(2)_L\times U(1)_Y$ Invariance

abstract:
  We reexamine the contact interaction hypothesis for excess high-$Q^2$ events
seen at HERA in $e^+ p \to e^+ X$ scattering. We consider the most general
structure of contact interactions insisting on $SU(3)_C\times SU(2)_L \times
U(1)_Y$ invariance. Apart from constraints for $e^+ e^- \to q\bar q$ ,
Drell-Yan and atomic parity violation experiments, we find stringent
constraints from neutrino deep inelastic data. A possible choice of contact
terms that escape present bounds is still possible, althought new data from
FERMILAB and LEP should further constrain such a possibility.


title: Dynamical Gauge Bosons and Grand Unified Theory

abstract:
  We propose that the difference of dynamical gauge bosons in asymptotically
non-free (ANF) gauge thoeries from elementary ones is the existence of the
compositeness condition at some scale $Lambda$. This shall be explained by
using non-linear Grassmannian like model where dynamical gauge bosons are
generated associated with the hidden local symmetry. Then we argue that ANF
gauge theories may provide another possible scenario of the ``standard model''
below GUT scale, where we shall see that infra-red stable points play essential
roles. The talk is based on the papers written with J. Sato and K. Yoshioka, T.
Takeuchi, T. Onogi and Y. Taniguchi and S. Tanimura (Invited talk at SCGT
workshop held in Nagoya in Novenber 1996).


title: Collimation of the e^+e^- annihilation event

abstract:
  The collimation $C$ of a hadronic event in the e^+e^- annihilation is defined
as the average of $\cos\theta$, $C=<\cos\theta>$, where $\theta$ is the angle
of each hadron measured from the thrust axis, and the average is over all the
hadrons produced in an event. It is an infrared-stable event-shape parameter.
$1-\bar C$, the difference between the unity and the average collimation at a
given energy, is proportional to the anomalous dimension of the hadron
multiplicity at the leading order in MLLA. Its next-to-leading order
corrections are calculated.


title: Democratic Seesaw Mass Matrix Model and New Physics

abstract:
  A seesaw mass matrix model is reviewed as a unification model of quark and
lepton mass matrices. The model can understand why top-quark mass m_t is so
singularly enhanced compared with other quark masses, especially, why m_t >>
m_b in contrast to m_u = O(m_d), and why only top-quark mass is of the order of
the electroweak scale Lambda_W, i.e., m_t = O(Lambda_W). The model predicts the
fourth up-quark t' with a mass m_{t'}= O(m_{W_R}), and an abnormal structure of
the right-handed up-quark mixing matrix U_R^u. Possible new physics is
discussed.


title: Higgs Decay to Order \alpha_s^4

abstract:
  We present in analytic form the three-loop O(\alpha_s^2) correction to the H
-> gg partial width of the standard-model Higgs boson with intermediate mass
M_H << 2 M_t. Its knowledge is required because the O(\alpha_s) correction is
so sizeable that the theoretical prediction to this order is unlikely to be
reliable. For M_H=100 GeV, the resulting QCD correction factor reads
$1+(215/12)\alpha_s^{(5)}(M_H)/\pi+150.419 (\alpha_s^{(5)}(M_H)/\pi)^2 \approx
1+0.66+0.21$. The new three-loop correction increases the Higgs-boson hadronic
width by an amount of order 1%.


title:
Infrared finite solutions for the gluon propagator and the QCD vacuum
  energy

abstract:
  Nonperturbative infrared finite solutions for the gluon polarization tensor
have been found, and the possibility that gluons may have a dynamically
generated mass is supported by recent Monte Carlo simulation on the lattice.
These solutions differ among themselves, due to different approximations
performed when solving the Schwinger-Dyson equations for the gluon polarization
tensor. Only approximations that minimize energy are meaningful, and, according
to this, we compute an effective potential for composite operators as a
function of these solutions in order to distinguish which one is selected by
the vacuum.


title: The Infrared Behavior of Gluon and Ghost Propagators in Landau Gauge QCD

abstract:
  A solvable systematic truncation scheme for the Dyson-Schwinger equations of
Euclidean QCD in Landau gauge is presented. It implements the Slavnov-Taylor
identities for the three-gluon and ghost-gluon vertices, whereas irreducible
four-gluon couplings as well as the gluon-ghost and ghost-ghost scattering
kernels are neglected. The infrared behavior of gluon and ghost propagators is
obtained analytically: The gluon propagator vanishes for small spacelike
momenta whereas the ghost propagator diverges stronger than a massless particle
pole. The numerical solutions are compared with recent lattice data for these
propagators. The running coupling of the renormalization scheme approaches a
fixed point, $\alpha_c \simeq 9.5$, in the infrared.


title: Initial Vortex Densities after a Temperature Quench

abstract:
  We calculate the initial density of relativistic global vortices (strings)
produced at a quench and contrast it with the predictions of Kibble and Zurek.