title:
Production mechanisms and single-spin asymmetry for kaons in high energy
  hadron-hadron collisions

abstract:
  Direct consequences on kaon production of the picture proposed in a recent
Letter and subsequent publications are discussed. Further evidence supporting
the proposed picture is obtained. Comparison with the data for the inclusive
cross sections in unpolarized reactions is made. Quantitative results for the
left-right asymmetry in single-spin processes are presented.


title: Solving the Supersymmetric CP Problem with Abelian Horizontal Symmetries

abstract:
  Models that combine Abelian horizontal symmetries and spontaneous CP
violation can (i) explain the smallness and hierarchy in quark parameters; (ii)
satisfactorily suppress supersymmetric contributions to flavor changing neutral
current processes; (iii) solve the $\mu$-problem; and (iv) suppress
supersymmetric contributions to CP violating observables to an acceptable
level. The CKM phase is $\O(1)$ and responsible, through Standard Model box
diagrams, to $\epsilon_K$. The supersymmetric CP violating phases are
suppressed, $\phi_A\sim\lambda^6$ and $\phi_B\sim\lambda^{8}$
($\lambda\sim0.2$), leading to an electric dipole moment of the neutron that is
about 2--3 orders of magnitude below the experimental bound.


title:
A Mean Field Approach To The Instanton-Induced Effect Close To The QCD
  Phase Transition

abstract:
  In the instanton models the chiral phase transition is driven by a transition
from random instanton-antiinstanton liquid and correlated
instanton-antiinstanton molecules. So far this phenomenon was studied by
numerical simulations, while we develop alternative semi-analytic approach. For
two massless quark flavors, both instantons and ``molecules" generate specific
4-fermion effective interactions. After those are derived, we determine the
temperature dependence of the thermodynamic quantities, the quark condensate
and the fraction of molecules using standard mean field method. Using
Bethe-Salpeter equation, we calculate T-dependence of mesonic correlation
functions.


title: From scattering amplitudes to cross sections in QCD

abstract:
  I describe how to calculate cross sections for hard-scattering processes in
high energy collisions at next to leading order in QCD. I consider
infrared-safe quantities and I assume that the scattering amplitudes are known
in analytic form up to next-to-leading order. The main topic is the description
of the algorithm for the analytic cancellation of the soft and collinear
singularities in the loop and bremsstrahlung contributions. The method is
systematic and general. It allows the construction of an analytic expression
for finite next-to-leading order hard scattering cross sections suitable for
numerical evaluation.


title:
Probing dissociation of space-like photons in deep-inelastic
  lepton-nucleon scattering

abstract:
  It is shown that the hadronic dissociation of space-like $(Q^2>0)$ photons
can be directly probed by performing measurements in the fragmentation region
of transversely polarized and unpolarized proton beams at the electron-proton
collider HERA. Measurements of momentum-distributions in the
photon-fragmentation region in normal and in LRG (large rapidity gap) events
are also suggested --- especially when the scattered proton or neutron in the
proton-beam direction is tagged. It is pointed out that such distributions can
yield useful information on the mechanisms of hadronic fragmentation in
general, and answer the following questions in particular: Is the well-known
hypothesis of limiting fragmentation (HFL) valid in color-exchange, in
flavor-exchange, or only in vacuum-quantum-number-exchange processes ?


title:
Lepton Polarization in the Decays $B\to X_s\mu^+\mu^-$ and $B\to
  X_s\tau^+\tau^-$

abstract:
  The effective Hamiltonian for the decay $b\to s l^+ l^-$ predicts a
characteristic polarization for the final state lepton, which can serve as an
important test of the underlying theory. The lepton polarization has, in
addition to a longitudinal component $P_L$, two orthogonal components $P_T$ and
$P_N$, lying in and perpendicular to the decay plane which are proportional to
$m_l/m_b$, and therefore significant for the $\tau^+\tau^-$ channel. The normal
polarization component $P_N$ is a $T$-odd effect connected with the
nonhermiticity of the effective Hamiltonian, arising mainly from $c\bar{c}$
intermediate states. We calculate all three polarization components for the
decay $B\to X_s\tau^+\tau^-$ as a function of the lepton pair mass, and find
average values $<P_L>$ = -0.37, $<P_T>$ = -0.63, $<P_N>$ = 0.03. By comparison,
the $\mu^-$ polarization is $<P_L>$ = -0.77, $<P_T> = <P_N>\approx 0$.


title: The $\mu$-Problem in Theories with Gauge-Mediated Supersymmetry Breaking

abstract:
  We point out that the $\mu$-problem in theories in which supersymmetry
breaking is communicated to the observable sector by gauge interactions is more
severe than the one encountered in the conventional gravity-mediated scenarios.
The difficulty is that once $\mu$ is generated by a one-loop diagram, then
usually $\bmu$ is also generated at the same loop order. This leads to the
problematic relation $\bmu \sim \mu \Lambda$, where $\Lambda \sim$ 10--100 TeV
is the effective supersymmetry-breaking scale. We present a class of theories
for which this problem is naturally solved. Here, without any fine tuning among
parameters, $\mu$ is generated at one loop, while $\bmu$ arises only at the
two-loop level. This mechanism can naturally lead to an interpretation of the
Higgs doublets as pseudo-Goldstone bosons of an approximate global symmetry.


title: Exclusive and inclusive weak decays of the B-meson

abstract:
  A relativistic quark model is applied to the description of semileptonic and
non-leptonic charmed decays of the B-meson. The exclusive semileptonic modes B
-> D l \nu and B -> D* l \nu are described through the universal Isgur-Wise
form factor, which is calculated in terms of a constituent quark model wave
function for the B-meson. Different approximations for the latter, either based
on a phenomenological ansatz or derived from analyses of the meson spectra, are
adopted. In particular, two wave functions, constructed via the Hamiltonian
light-front formalism using a relativized and a non-relativistic constituent
quark model, are considered, obtaining a link between standard spectroscopic
quark models and the B-meson decay physics. The inclusive semileptonic and
non-leptonic branching ratios are calculated within a convolution approach,
inspired by the partonic model and involving the same B-meson wave function
used for the evaluation of the exclusive semileptonic modes. Our results for
the major branching ratios are consistent with available experimental data and
the sum of all the calculated branching ratios turns out to be close to unity.
In particular, we found that: i) a remarkable fraction (~ 35%) of semileptonic
decay modes occur in non-D, non-D* final states; ii) non-perturbative effects
enhance the inclusive b -> c \bar{u} d decay channels, with a sizable
contribution provided by internal decays into heavy mesons and
baryon-antibaryon pairs; the resulting reduction of the semileptonic branching
ratio brings the theoretical prediction in agreement with the experimental
value without increasing at the same time the charm counting.


title:
Pair Production and Correlated Decay of Heavy Majorana Neutrinos in
  $e^+e^-$ Collisions

abstract:
  We consider the process $e^+e^-\to N_1N_2$, where $N_1$ and $N_2$ are heavy
Majorana particles, with relative $CP$ given by $\eta_{CP}=+1$ or $-1$,
decaying subsequently via $N_1,N_2\to W^{\pm}e^{\mp}$. We derive the energy and
angle correlation of the dilepton final state, both for like-sign
($e^{\mp}e^{\mp}$) and unlike-sign ($e^-e^+$) configurations. Interesting
differences are found between the cases $\eta_{CP}=+1$ and $-1$. The
characteristics of unlike-sign $e^+e^-$ dileptons originating from a Majorana
pair $N_1N_2$ are contrasted with those arising from the reaction $e^+e^-\to
N\bar{N}\to W^+e^-W^-e^+$, where $N\bar{N}$ is a Dirac particle-antiparticle
pair.


title:
Solving the Crisis in Big-Bang Nucleosynthesis by the Radiative Decay of
  an Exotic Particle

abstract:
  We discuss a new mechanism which can solve the crisis in standard big-bang
nucleosynthesis. A long-lived particle $X$ ($10^4 sec \lesssim \tau_X \lesssim
10^6 sec$) which decays into photon(s) will induce cascade photons, and destroy
significant amounts of D and $^3$He without destroying $^4$He or too much
$^7$Li. We numerically investigate this process and derive a constraint on the
properties of $X$ such that the theoretical values of the primordial
light-element abundances agree with observation. We also present some
candidates for the unstable particle $X$.


title: Neutrino Moments and the Magnetic Primakoff Effect

abstract:
  If different species of neutrinos possess transition magnetic moments, a
conversion between species can occur in the Coulomb field of a nucleus. In the
case of Dirac neutrinos this corresponds to an active to sterile conversion,
whereas in the case of Majorana neutrinos, the conversion takes place between
active species. The conversion cross sections grow with the energy of the
incident neutrino. The formalism is also applied to a new type of experiment
designed to test the existence of the ``KARMEN anomaly''.


title:
Selectron Searches in $e^-e^-$, $e^-\gamma$ and $\gamma\gamma$
  Scattering

abstract:
  We review the selectron production mechanisms in the linear collider modes
which do not require positrons. The standard model backgrounds can be rendered
harmless or even be nearly eliminated with polarized beams. We insist on the
complementarity of these different experiments.


title: The $B_s$ width difference beyond the Standard Model

abstract:
  The Standard Model predicts a large width difference in the $B_s$ system. New
physics can contribute significantly to the {\it mass} difference. If this
contribution is CP violating, this will always result in a reduction of the
{\it width} difference. The analyses of measurements of the width difference
using $B_s$ decays into CP eigenstates have to be modified in the presence of
new physics. We discuss how the width difference and the new CP violating phase
in $B_s$ mixing can be measured.


title: Two-Dimensional Solitons at Finite Temperature

abstract:
  The partition function of two-dimensional solitons in a heat bath of mesons
is worked out to one-loop. For temperatures large compared to the meson mass,
the free energy is dominated by the meson-soliton bound states and the zero
modes, a consequence of Levinson's theorem. Using the Bethe-Uhlenbeck formula
we compare the soliton energy-shift to the shift expected in the pole mass
using a virial expansion. We construct the partition function associated to a
fast moving soliton at finite temperature, and found that the soliton thermal
inertial mass is no longer constrained by Poincare's symmetry. At finite
temperature, the concept of quasiparticles is process dependent.


title: QCD Corrections to Decays of Intermediate Mass Higgs Boson

abstract:
  The brief discussion of the studies of the radiative QCD corrections to the
decay widths and branching ratios of the Standard Model Higgs boson with the
mass 2 m_b < M_H < 2 M_W is given. The numerical results are obtained with the
help of our FORTRAN code SEEHIGGS.


title:
Top-Quark Decay Via the Anomalous Coupling $\bar t c \gamma$ at Hadron
  Colliders

abstract:
  We determine the constraints on the anomalous top-quark coupling associated
with the flavor-changing neutral current vertex $\bar t c \gamma $ from the
limits on the $b$-quark rare decay $b\rightarrow s \gamma$ and non-standard
top-quark decays. Based on these constraints, we discuss the experimental
observability of the rare decay mode $t \rightarrow c \gamma$, both at the
Fermilab Tevatron with a luminosity-upgrade and at the LHC.


title:
Exact O(alpha) Corrections to the Single Hard Bremsstrahlung Process in
  Low Angle Bhabha Scattering in the SLC/LEP Energy Regime

abstract:
  We present the exact O(alpha) correction to the process e+ e- -> e+ e- +
gamma in the low angle luminosity regime at SLC/LEP energies. We give explicit
formulas for the completely differential cross section. As an important
application, we illustrate the size of the respective corrections of O(alpha^2)
to the SLC/LEP luminosity cross section. We show explicitly that our results
have the correct infrared limit, as a cross-check. Some comments are made about
the implementation of our results in the framework of a Monte Carlo event
generator. This latter implementation will appear elsewhere.


title: Gauge-Invariant Decomposition of Nucleon Spin and Its Spin-Off

abstract:
  I introduce a gauge invariant decomposition of the nucleon spin into quark
helicity, quark orbital, and gluon contributions. The total quark (and hence
the quark orbital) contribution is shown to be measurable through virtual
Compton scattering in a special kinematic region where single quark scattering
dominates. This deeply-virtual Compton scattering (DVCS) has much potential to
unravel the quark and gluon structure of the nucleon.


title:
Internal W-emmission and W-exchange Contributions to {\bf B}\to {{\bf
  D}^{(*)} Decays

abstract:
  We evaluate external $W$-emission, internal $W$-emission and $W$-exchange
contributions to nonleptonic $B\to D^{(*)}$ decays based on the perturbative
QCD formalism including Sudakov effects, whose ratio is found to be
$1:+0.2:0.03i$ at the amplitude level. We observe that the internal
$W$-emission contribution is additive to the external $W$-emission
contribution, and that the $W$-exchange contribution is negligible and mainly
imaginary, its real part being at least one order of magnitude smaller than the
imaginary part. Our predictions are consistent with the CLEO data and with
those obtained by the Bauer-Stech-Wirbel method.


title: Effective chiral Lagrangians for spin-1 mesons

abstract:
  The commonly used types of effective theory for vector mesons are reviewed
and their relationships clarified. They are shown to correspond to different
choices of field for spin-1 particles and the rules for transforming between
them are described. The importance of respecting chiral symmetry is stressed.
The choice of fields that transform homogeneously under the nonlinear
realisation of chiral symmetry imposes no preconceptions about the types of
coupling for the mesons. This representation thus provides a convenient
framework for relating different theories. It is also used to elucidate the
nature of the assumptions in specific hidden-gauge and massive Yang-Mills
models that have been widely used.


title:
Sea Contributions to Spin 1/2 Baryon Structure, Magnetic Moments, and
  Spin Distribution

abstract:
  We treat the baryon as a composite system made out of a \lq\lq core" of three
quarks (as in the standard quark model) surrounded by a \lq\lq sea" (of gluons
and $q\bar{q}$-pairs) which is specified by its total quantum numbers like
flavor, spin and color. Specifically, we assume the sea to be a flavor octet
with spin 0 or 1 but no color. The general wavefunction for spin 1/2 baryons
with such a sea component is given. Application to the magnetic moments is
considered. Numerical analysis shows that a scalar (spin 0) sea with an
admixture of a vector (spin 1) sea can provide very good fits to the magnetic
moment data {\em using experimental errors}. Our best fit automatically gives
$g_A/g_V$ for neutron beta decay in agreement with data. This fit also gives
reasonable values for the spin distributions of the proton and neutron.


title: A New Supersymmetric CP Violating Contribution to Neutral Meson Mixing

abstract:
  We study the contribution to flavor changing neutral current processes from
box diagrams with light higgsinos and squarks. Starting with just the Cabbibo
Kobayashi Maskawa (CKM) phase, we find contributions to the $K^0$ and $B^0$
meson mass matrices that are out of phase with the Standard Model contributions
in the case of substantial mixing between the up-type squarks. This difference
in phase could be large enough to be detected at the proposed $B$ factories,
with interesting implications for the unitarity triangle of CKM matrix
elements.


title:
Scalar Sea Contributions to Spin 1/2 Baryon Structure and Magnetic
  Moments

abstract:
  We treat the baryon as a composite system made out of a "core" of three
quarks (as in the standard quark model) surrounded by a "sea" (of gluons and
$q\bar{q}$-pairs) which is specified by its total quantum numbers like flavor,
spin and color. Specifically, we assume the sea to be a flavor octet with spin
0 but no color. The general wavefunction for spin 1/2 baryons with such a sea
component is given and an application to the magnetic moments is considered.
Numerical analysis shows that the scalar sea can provide a good fit to the
magnetic moment data using experimental errors.


title: A Priori Mixed Baryons and Weak Radiative Decays

abstract:
  A priori mixings of eigenstates in physical states are quantum mechanical
effects well known in several realms of physics. The possibility that such
effects are also present in particle physics, in the form of flavor and parity
mixings, is studied. An application to weak radiative decays of hyperons is
discussed. It is suggested that this scheme may also be present in non-leptonic
and rare mode decays as the enhancement phenomenon.


title:
Determination of the Kobayashi-Maskawa-Cabibbo matrix element V_{us}
  under various flavor-symmetry-breaking models in hyperon semileptonic decays

abstract:
  We study the success to describe hyperon semileptonic decays of four models
that incorporate second-order SU(3) symmetry breaking corrections. The criteria
to assess their success is by determining V_{us} in each of the three relevant
hyperon semileptonic decays and comparing the values obtained with one another
and also with the one that comes from K_{l3} decays. A strong dependence on the
particular symmetry breaking model is observed. Values of V_{us} which do not
agree with the one of K_{l3} are generally obtained. However, in the context of
chiral perturbation theory, only the model whose corrections are O(m_s) and
O(m_s^{3/2}) is successful. Using its predictions for the f_1 form factors one
can quote a value of V_{us} from this model, namely, V_{us}=0.2176\pm 0.0026,
which is in excellent agreement with the K_{l3} one.


title: Nucleons at Finite Temperature

abstract:
  The nucleon mass shift is calculated using chiral counting arguments and a
virial expansion, without and with the $\Delta$. At all temperatures, the mass
shift and damping rate are dominated by the $\Delta$. Our results are compared
with the empirical analysis of Leutwyler and Smilga, as well as results from
heavy baryon chiral perturbation theory in the large $N_{c}$ (number of color)
limit. We show that unitarity implies that the concepts of thermal shifts are
process dependent.


title: Right Handed Neutrino Currents in the SU(3)_LxU(1)_N Electroweak Theory

abstract:
  A version of the $\mbox{SU(3)}_L\otimes \mbox{U(1)}_N$ electroweak theory in
which there are right-handed neutrino currents is reconsidered in detail. We
argue that in order to have a result consistent with low-energy one, the
right-handed neutrino component must be treated as correction instead of an
equivalent spin state. The data from the $Z$-decay allow us to fix the limit
for $\phi$ as $-0.00285 \leq \phi \leq 0.00018$. From the neutrino neutral
current scattering, we estimate a bound for the new neutral gauge boson $Z^2$
mass in the range of 400 GeV. A bound for the new charged and neutral
(non-Hermitian) gauge bosons $Y^{\pm}, X^o$ is also obtained from
symmetry-breaking hierarchy.


title: Effective mass of phi mesons at finite temperature

abstract:
  The effective mass of phi meson at non-zero temperature is re-examined with
an effective chiral Lagrangian. We find that the phi mass decreases with
temperature but the effect is small compared to the result obtained from
calculations using QCD sum rules. The leading contributions come from kaon loop
corrections but vector meson contributions are also important as temperature
increases. We discuss consequences of these changes to the phenomena of chiral
phase transition in hot hadronic matter.


title: Structure Functions of the Nucleon in a Covariant Scalar Spectator Model

abstract:
  Nucleon structure functions, as measured in deep-inelastic lepton scattering,
are studied within a covariant scalar diquark spectator model. Regarding the
nucleon as an approximate two-body bound state of a quark and diquark, the
Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in
the ladder approximation. The valence quark distribution is discussed in terms
of the solutions of the BSE.


title: Two-loop QCD corrections to $b\to c$ transitions at zero recoil

abstract:
  Complete two-loop QCD corrections to $b\to c$ transitions are presented in
the limit of zero recoil. Vector and axial-vector coefficients $\eta_{A,V}$ are
calculated analytically in the limit of equal beauty and charm masses, and a
series appoximation is obtained for the general mass case. $\eta_A$ is crucial
for the determination of the absolute value of the Cabibbo-Kobayashi-Maskawa
matrix element $V_{cb}$. The two-loop effects enhance the one-loop corrections
by 21\%, removing a major theoretical uncertainty in the value of $|V_{cb}|$.
Including two-loop QCD effects and previously neglected electroweak and Coulomb
corrections we find $|V_{cb}| = 0.0379 \pm 0.0020({\rm stat}) \pm 0.0025({\rm
syst}) \pm 0.0011({\rm theory})$.


title:
Production of pseudovector ($J^{PC}=1^{++}$) heavy quarkonia by virtual
  $Z$ boson in $e^+e^-$ collisions

abstract:
  It is shown that $BR(\chi_{b1}(1P)\rightarrow Z\rightarrow e^+e^-)\simeq
3.3\cdot 10^{-7}$, $BR(\chi_{b1}(2P)\rightarrow Z\rightarrow e^+e^-)\simeq
4.1\cdot 10^{-7}$ and $BR(\chi_{c1}(1P)\rightarrow Z\rightarrow e^+e^-)\simeq
10^{-8}$ that give a good chance to search for the direct production of
pseudovector $^3P_1$ heavy quarkonia in $e^+e^-$ collisions ($e^+e^-\rightarrow
Z\rightarrow ^3P_1$) even at current facilities not to mention $b$ and $c-\tau$
factories.


title: The Parton Model Approach to Inclusive B meson Decays

abstract:
  We test the parton model approach to inclusive $B \ra \gamma X_s$ and $B \ra
e \bar{\nu} X_u$ processes by calculating a few moments of the distribution
function. The $1/m_Q$ expansion of $b$-quark distribution function is
discussed. We show that Peterson's fragmentation function is useful as the
distribution function of $b$-quark but requires some improvements. By extension
of Peterson's arguments, we obtain the refined form for the distribution
function and with the refined function, we obtain the consistent results with
the HQET.


title: A renormalizable extension of the NJL-model

abstract:
  The Nambu-Jona-Lasinio model is supplemented by the quark interaction
generated by the one-gluon exchange. The employed gluon propagator exhibits the
correct large momentum behavior of QCD, whereas the Landau-pole at low energies
is screened. The emerging constituent quark model is one-loop renormalizable
and interpolates between the phenomenologically successful Nambu-Jona-Lasinio
model at low energies and perturbative QCD at high momenta. Consequently, the
momentum dependence of the quark self-energy at high energy coincides with the
prediction from perturbative QCD. The chiral phase transition is studied in
dependence on the low energy four quark interaction strength in the
Dyson-Schwinger equation approach. The critical exponents of the quark
self-energy and the quark condensate are obtained. The latter exponent deviates
from the NJL-result. Pion properties are addressed by means of the
Bethe-Salpeter equation. The validity of the Gell-Mann-Oakes-Renner relation is
verified. Finally, we study the conditions which are necessary to allow for an
accurate estimate of observables by the NJL-model as well as the shortcoming of
the NJL-model due to its inherent non-renormalizability.


title:
Final state QCD corrections to off-shell single top production in hadron
  collisions

abstract:
  In this paper, I study final state QCD radiative corrections to off-shell
single top production via decaying $W$ at hadron collider energies. The tree
level Breit-Wigner distribution of the produced top invariant mass is distorted
by final state QCD radiation, while the peak position remains unchanged. The
exact one loop QCD calculation and the narrow width approximation agree in
predicting the cross section, the hadronic transverse energy distribution and
the bottom-lepton invariant mass distribution.


title: Color-Octet $J/\psi$ Production at Low $p_\perp$

abstract:
  We study contributions from color-octet quarkonium formation mechanisms to
$J/\psi$ hadroproduction at low $p_\perp$. We include transitions of
color-octet $c\bar{c}$ states into ``direct'' $J/\psi$ and into $\chi_{1,2}$
which decay radiatively into a $J/\psi$. Together with earlier work, this
calculation constitutes a complete analysis of $p_\perp$-integrated $J/\psi$
production at leading twist. We find that the leading-twist contribution is not
sufficient to reproduce the observed production rates and polarization of the
$J/\psi$ and $\chi_{1,2}$. Hence there must exist other important quarkonium
production mechanisms at low $p_\perp$.


title: Explicit solutions of the 3--loop vacuum integral recurrence relations

abstract:
  Explicit formulas for the solutions of the recurrence relations for 3--loop
vacuum integrals are suggested. This formulas can be used for direct
calculations and demonstrate a high efficiency. They also produce a new type of
recurrence relations over the space--time dimension.


title: Radiative Contributions to TGC in the MSSM

abstract:
  We give a brief account of recent calculations of radiative contributions to
the Triple Gauge Couplings (TGC) from the Minimal Supersymmetric Standard Model
(MSSM), at a 500 GeV $e^+e^-$ collider. Our results indicate that, although
these MSSM virtual contributions indeed are of the order of the expected
accuracy on TGC measurements, the generally neglected box contributions to TGC
also are likely to be relevant at such high energies.


title:
Discriminating signal from background using neural networks. Application
  to top-quark search at the Fermilab Tevatron

abstract:
  The application of Neural Networks in High Energy Physics to the separation
of signal from background events is studied. A variety of problems usually
encountered in this sort of analyses, from variable selection to systematic
errors, are presented. The top--quark search is used as an example to
illustrate the problems and proposed solutions.


title: QCD Corrections to W Pair Production at LEP200

abstract:
  One loop QCD corrections to hadronic W decay are calculated for arbitrary W
polarizations . The results are applied to W pair production and decay at
LEP200. We focus on the corrections to angular distributions with particular
emphasis on azimuthal distributions and correlations. The relevance of our
results to the experimental determination of possible nonstandard triple gauge
bosons interactions is discussed.


title: Detecting Gluino-Containing Hadrons

abstract:
  When SUSY breaking produces only dimension-2 operators, gluino and photino
masses are of order 1 GeV or less. The gluon-gluino bound state has mass
1.3-2.2 GeV and lifetime > 10^{-5} - 10^{-10} s. This range of mass and
lifetime is largely unconstrained because missing energy and beam dump
techniques are ineffective. With only small modifications, upcoming K^0 decay
experiments can study most of the interesting range. The lightest
gluino-containing baryon (uds-gluino) is long-lived or stable; experiments to
find it and the uud-gluino are also discussed.


title:
New dark matter candidates motivated from superstring derived
  unification

abstract:
  Perturbative gauge coupling unification in realistic superstring models
suggests the existence of additional heavy down-type quarks, beyond the minimal
supersymmetric standard model. The mass scale of the heavy down-type quarks is
constrained by requiring agreement between the measured low energy gauge
parameters and the string-scale gauge coupling unification. These additional
quarks arise and may be stable due to the gauge symmetry breaking by ``Wilson
lines'' in the superstring models. We argue that there is a window in the
parameter space within which this down-type quark is a good candidate for the
dark matter.


title: Quantising the B=2 and B=3 Skyrmion systems

abstract:
  We examine the quantisation of a collective Hamiltonian for the two-baryon
system derived by us in a previous paper. We show that by increasing the
sophistication of the approximations we can obtain a bound state - or a
resonance - not too far removed from the threshold with the quantum numbers of
the deuteron. The energy of this state is shown to depend very sensitively on
the parameters of the model. Subsequently we construct part of a collective
Hamiltonian for the three baryon system. Large-amplitude quantum fluctuations
play an important r\^ole in the intrinsic wave function of the ground-state,
changing its symmetry from octahedral to cubic. Apart from the tetrahedron
describing the minimum of the potential, we identify a ``doughnut'' and a
``pretzel'' as the most important saddle points in the potential energy
surface. We show that it is likely that inclusion of fluctuations through these
saddle points lead to an energy close to the triton's value.


title: Possible retardation effects of quark confinement on the meson spectrum

abstract:
  The reduced Bethe-Salpeter equation with scalar confinement and vector gluon
exchange is applied to quark-antiquark bound states. The so called intrinsic
flaw of Salpeter equation with static scalar confinement is investigated. The
notorious problem of narrow level spacings is found to be remedied by taking
into consideration the retardation effect of scalar confinement. Good fit for
the mass spectrum of both heavy and light quarkomium states is then obtained.


title: Top Quark Decays into Heavy Quark Mesons

abstract:
  For top quark decays into heavy quark mesons $\Upsilon$ and $\bar{B}_c^*$ , a
complete calculation to the leading order both in QCD coupling constant
$\alpha_s$ and in $v$, the typical velocity of the heavy quarks inside the
mesons, is performed. Relatons between the top quark mass and the decay
branching ratios are studied. Comparion with the results which are obtained by
using the quark frangmentation functions is also discussed. The branching
ratios are consistent (within a factor of $2\sim 3 $) with that obtained using
fragmentation functions at $m_t\sim 150$ GeV.


title:
K-Matrix Analysis of the (${IJ}^{PC}=00^{++}$) Amplitude in the Mass
  Region up to 1550 MeV

abstract:
  K-matrix analysis of the $00^{++}$ wave is performed in the channels
$\pi\pi,~K\bar K,~\eta\eta$ and $4\pi$ in the mass region up to 1550 MeV. The
fit is based on the following data: $p\bar p ~(at~rest)\to \pi^0\pi^0\pi^0$,
$\pi^0\pi^0\eta,~\pi^0\eta\eta$ [1,2], $\pi N\to \pi\pi N$ [3,4], $\pi N\to
K\bar K N$ [5] and the inelastic cross section of the $\pi\pi$ interaction [6].
Simultaneous analysis of these data confirms the existence of the scalar
resonances: $f_0(980),~f_0(1300)$ and $f_0(1500)$, the poles of the amplitude
being at the following complex masses (in MeV): $(1008\pm 10)- i(43\pm 5)$,
$(1290\pm 25)-i(120\pm 15)$, and $(1497\pm 6)-i(61\pm 5)$. The fourth pole has
sunk deeply into the complex plane: $(1430 \pm 150) - i(600\pm 100)$. Positions
of the K-matrix poles (which are referred to the masses of bare states) are at
$750\pm 120$ MeV, $1240\pm 30$ MeV, $1280\pm 30$ MeV and $1615\pm 40$ MeV.
Coupling constants of the K-matrix poles to the $\pi\pi$, $\eta\eta$ and $K\bar
K$ channels are found that allow us to analyze the quark and gluonic content of
bare states. It is shown that $f_0^{bare}(1240)$ and $f_0^{bare}(1615)$ (which
are strongly related to $f_0(1500)$) can be considered as good candidates for
scalar glueball.


title: Top Quark Condensate Revisited

abstract:
  In the light of recent discovery of a very heavy top quark, we reexamine the
top quark condensate model proposed by Miransky, Tanabashi and Yamawaki (MTY)
and by Nambu. We first review the original MTY formulation based on the ladder
Schwinger-Dyson equation and the Pagels-Stokar formula. It is particularly
emphasized that the critical phenomenon gives a simple reason why the top quark
can have an extremely large mass compared with other quarks and leptons. Then
we discuss the Bardeen-Hill-Lindner (BHL) formulation based on the
renormalization-group equation and the compositeness condition, which
successfully picks up 1/N_c-sub-leading effects disregarded by MTY. In fact BHL
is equivalent to MTY at the 1/N_c-leading order. Such a simplest version of the
model predicts the top quark mass, m_t \simeq 250 GeV (MTY) and m_t \simeq 220
GeV (BHL), for the cutoff on the Planck scale. In this version we cannot take
the cutoff beyond the Landau pole of U(1)_Y gauge coupling, which yields a
minimum value of the top mass prediction m_t \simeq 200 GeV. We then propose a
``top mode walking GUT'' : The standard gauge groups are unified into a
(``walking'') GUT so that the cutoff can be taken to infinity thanks to the
renormalizability of the four-fermion theory coupled to ``walking'' gauge
theory. The top and Higgs mass prediction is then controlled by the
Pendleton-Ross infrared fixed point at GUT scale and can naturally lead to m_t
\simeq m_H \simeq 180 GeV.


title: Chiral corrections to the Kroll-Ruderman theorem

abstract:
  We calculate the one--loop corrections to the Kroll--Ruderman low--energy
theorems for charged pion photoproduction in the framework of heavy baryon
chiral perturbation theory. We predict the threshold S--wave multipole $E_{0+}$
to be $E_{0+}^{\rm thr}(\gamma p \to \pi^+ n) = ( 28.2 \pm 0.6 )\cdot
10^{-3}/M_{\pi}$ and $E_{0+}^{\rm thr} (\gamma n \to\pi^- p) = ( -32.7 \pm 0.6
)\cdot 10^{-3}/M_{\pi}$, respectively, for a fixed pion--nucleon coupling
constant, $g_{\pi N} = 13.4$. A comparison to the existing data is also given.


title: Novel Mechanism of Nucleon Stopping in Heavy Ion Collisions

abstract:
  When a diquark does not fragment directly but breaks in such a way that only
one of its quarks gets into the produced baryon, the latter is produced closer
to mid rapidities. The relative size of this diquark breaking component
increases quite fast with increasing energy. We show that at a given energy it
also increases with the atomic mass number and with the centrality of the
collision and that it allows to explain the rapidity distribution of the net
baryon number ($p$-$\bar{p}$) in $SS$ central collisions. Predictions for
$Pb$-$Pb$ collisions are presented.


title: Instantons in QCD: Theory and application of the instanton liquid model

abstract:
  Numerical and anaytical studies of the instanton liquid model have allowed
the determination of many hadronic parameters during the last 13 years. Most
part of this thesis is devoted to the extension of the analytical methods. The
meson correlation (polarization) functions are calculated in the instanton
liquid model including dynamical quark loops. The correlators are plotted and
masses and couplings of the $\sigma$, $\rho$, $\omega$, $a1$ and $f1$ are
obtained from a spectral fit. A separated analysis allows the determination of
the $\eta'$ mass too. The results agree with the experimental values on a 10\%
level. Further I give some predictions for the proton form factors, which are
related to the proton spin (problem). A gauge invariant gluon mass for small
momenta is also calculated. At the end of the work some predictions are given,
which do not rely on the instanton liquid model. A gauge invariant quark
propagator is calculated in the one instanton background and is compared to the
regular and singular propagator. An introduction to the skill of choosing a
suitable gauge, especially a criterium for choosing regular or singular gauge,
is given. An application is the derivation of a finite relation betweewn the
quark condensate and the QCD scale $\Lambda$, where neither an infrared cutoff
nor a specific instanton model has been used. In general the instanton liquid
model exhibits an astonishing internal consistency and a good agreement with
the experimental data.


title: The Subjet Multiplicity in Quark and Gluon Jets

abstract:
  We calculate the mean number of subjets in quark and gluon jets in the final
state of e^+e^- annihilation. Since `quark' and `gluon' jets are
scheme-dependent objects, we stress the importance of using the same definition
as in experimental analyses. We define the jets using the k_perp algorithm at a
coarse scale y_1, and the subjets using a finer scale y_0, in the same
algorithm. Gluon jets are anti-tagged by the presence of heavy quarks in both
other jets. Our result is exact to leading order in alpha_s, and resums leading
and next-to-leading logarithmic terms in the ratio y_1/y_0 to all orders in
alpha_s.


title:
A Predictive SUSY SO(10) X Delta (48) X U(1) Model for CP Violation,
  Neutrino Oscillation, Fermion Masses and Mixings with Very Low tan(beta)

abstract:
  Assuming universality of Yukawa coupling of the superpotential and maximal
spontaneous CP violation, fermion masses and mixing angles including that of
neutrinos are studied in an SUSY SO(10)$\times \Delta (48)\times$ U(1) model
with small $\tan \beta$. The low energy parameters of the standard model are
determined solely by the Clebsch factors of the symmetry group and the
structure of the physical vacuum. Thirteen parameters involving masses and
mixing angles in the quark and charged lepton sector are successfully predicted
by only four parameters with three of them determined by the scales of
U(1)$\times \Delta(48)$, SO(10), SU(5) and SU(2)$_{L}$ symmetry breakings. An
interesting prediction on ten parameters concerning the neutrino sector is also
made by using the same four parameters. An additional parameter is added to
obtain the mass and mixing of a sterile neutrino. It is found that the LSND
$\bar{\nu}_{\mu} \rightarrow \bar{\nu}_{e}$ events, atmospheric neutrino
deficit and the mass limit put by hot dark matter can be naturally explained.
Solar neutrino puzzle can be solved only by introducing a sterile neutrino.
$(\nu_{e} - \nu_{\tau})$ oscillation is found to have the same sensitive region
as the $(\nu_{e} - \nu_{\mu})$ oscillation. The hadronic parameters $B_{K}$ and
$f_{B}\sqrt{B}$ are extracted from the observed $K^{0}$-$\bar{K}^{0}$ and
$B^{0}$-$\bar{B}^{0}$ mixings respectively. The direct CP violation
($\varepsilon'/\varepsilon$) in kaon decays and the three angles $\alpha$,
$\beta$ and $\gamma$ of the unitarity triangle in the CKM matrix are also
presented. More precise measurements of $\alpha_{s}(M_{Z})$, $|V_{cb}|$,
$|V_{ub}/V_{cb}|$, $m_{t}$, as well as various CP violation and neutrino
oscillation experiments will provide crucial tests for the present model.


title:
Discovering Non-Abelian Weak Couplings and an Anomalous Magnetic Dipole
  Moment of the $W^{\pm}$ at LEP~2

abstract:
  In view of the forthcoming results on $W^{\pm}$ pair production at LEP~2, we
emphasize that {\em direct empirical evidence} on non-trivial properties of the
weak vector bosons can be obtained with relatively limited integrated
luminosity. An integrated luminosity of $10\;\mathrm{pb}^{-1}$ at
$\sqrt{s}=175$ GeV will be sufficient to provide direct experimental evidence
for non-vanishing self-couplings of non-Abelian type among the weak vector
bosons. An integrated luminosity of $100\;\mathrm{pb}^{-1}$ at $\sqrt{s}=175$
GeV will provide direct evidence for the existence of an anomalous magnetic
dipole moment of the charged vector bosons $W^{\pm}$.


title: QCD Structure of Leptons

abstract:
  The QCD structure of the electron is defined and calculated. The leading
order splitting functions are extracted, showing an important contribution from
$\gamma$-$Z$ interference. Leading logarithmic QCD evolution equations are
constructed and solved in the asymptotic region where log$^2$ behaviour of the
parton densities is observed. Corrections to the naive evolution procedure are
demonstrated. Possible applications with clear manifestation of 'resolved'
photon and weak bosons are discussed.


title:
Excitation of open charm and factorization breaking in rapidity gap
  events at HERA

abstract:
  We develop the pQCD description of diffraction excitation of heavy flavours
in DIS and we derive the analytic formulas for the mass spectrum in leading
log$m_f^{2}$. The result illustrates nicely non-factorization properties of the
QCD pomeron. We predict a very steep rise of the charm content of diffraction
dissociation of photons at small $x_{\Pom}$. We evaluate the contribution of
open charm to scaling violations in the structure function of the pomeron.


title: Gottfried and Bjorken integrals and gluon polarization in the proton

abstract:
  We show that the Gottfried and the Bjorken integrals have the same
nonperturbative evolution, which is related to the gluon polarization in the
proton.


title:
Exact Duality and Bjorken Sum Rule in Heavy Quark Models \`a la
  Bakamjian-Thomas

abstract:
  The heavy mass limit of quark models based on the Bakamjian-Thomas
cons\-truction reveals remarkable features. In addition to previously
demonstrated properties of covariance and Isgur-Wise scaling, exact duality,
leading to the Bjorken-Isgur-Wise sum rule, is proven, for the first time to
our knowledge in relativistic quark models. Inelastic as well as elastic
contributions to the sum rule are then discussed in terms of ground state
averages of a few number of operators corresponding to the nonrelativistic
dipole operator and various relativistic corrections.


title: MC simulation of vector boson production in polarized proton collisions

abstract:
  We present a Monte Carlo (MC) study of $W^{\pm}$ and $Z_{0}$ production of
longitudinally polarized proton collisions at a center of mass (CMS) energy of
$500\,{\rm GeV}$. All results were obtained with the SPHINX MC code. We
consider two different types of polarized parton distributions with large and
small gluon polarization. Various spin asymmetries are found to be sensitive to
the shape of the polarized gluon distribution between
$0.1\stackrel{<}{\sim}x\stackrel{<}{\sim}0.5$. The asymmetries are
approximately constant with respect to the transverse momentum carried by the
$W^{\pm}$ and $Z_{0}$, {\em except} if the first moment of the gluon
polarization is large. In this case some $W^{\pm}$ asymmetries show a
significant variation with transverse momentum.


title: Modelling the nucleon wave function from soft and hard processes

abstract:
  Current light-cone wave functions for the nucleon are unsatisfactory since
they are in conflict with the data of the nucleon's Dirac form factor at large
momentum transfer. Therefore, we attempt a determination of a new wave function
respecting theoretical ideas on its parameterization and satisfying the
following constraints: It should provide a soft Feynman contribution to the
proton's form factor in agreement with data; it should be consistent with
current parameterizations of the valence quark distribution functions and
lastly it should provide an acceptable value for the $\jp \to N \bar N$ decay
width. The latter process is calculated within the modified perturbative
approach to hard exclusive reactions. A simultaneous fit to the three sets of
data leads to a wave function whose $x$-dependent part, the distribution
amplitude, shows the same type of asymmetry as those distribution amplitudes
constrained by QCD sum rules. The asymmetry is however much more moderate as in
those amplitudes. Our distribution amplitude resembles the asymptotic one in
shape but the position of the maximum is somewhat shifted.


title: Dilepton and Photon Emission Rates from a Hadronic Gas

abstract:
  We analyze the dilepton and photon emission rates from a hadronic gas using
chiral reduction formulas and a virial expansion. The emission rates are
reduced to pertinent vacuum correlation functions, most of which can be
assessed from experiment. Our results indicate that in the low mass region, the
dilepton and photon rates are enhanced compared to most of the calculations
using chiral Lagrangians. The enhancement is further increased through a finite
pion chemical potential. An estimate of the emission rates is also made using
Haag's expansion for the electromagnetic current. The relevance of these
results to dilepton and photon emission rates in heavy-ion collisions is
discussed.


title: A study on the rare radiative decay $B_c \to D_s^* \gamma$

abstract:
  We study the decay $B_c \rightarrow D_s^* \gamma$. There are two mechanisms
contributing to the process. One proceeds through the short distance
$b{\rightarrow}s\gamma$ transition and the other occurs through weak
annihilation accompanied by a photon emission.The electromagnetic penguin
contribution is estimated by perturbative QCD and found to be
$4.68\times10^{-18}$ GeV. In particular, we find the contribution of the weak
annihilation is $6.25\times10^{-18}GeV$ which is in the same order as that of
the electromagnetic penguin. The total decay rate $\Gamma(B_c \rightarrow D_s^*
\gamma)$ is predicted to be $1.45\times10^{-17}GeV$ and the branching ratio
$Br(B_c \rightarrow D_s^* \gamma)$ is predicted to be $2.98\times 10^{-5}$ for
$\tau_{B_c}=1.35ps$. The the decays $B_c \rightarrow D_s^* \gamma$ can be well
studied at LHC in the near future.


title:
Structures of Neutrino Flavor Mixing Matrix and Neutrino Oscillations at
  CHORUS and NOMAD

abstract:
  We have studied structures of the neutrino flavor mixing matrix focusing on
the neutrino oscillations at CHORUS and NOMAD as well as the one at LSND(or
KARMEN). We have assumed two typical neutrino mass hierarchies $m_3\simeq
m_2\gg m_1$ and $m_3\gg m_2\gg m_1({\rm or}\simeq m_1)$. Taking into account
the see-saw mechanism of neutrino masses, the reasonable neutrino flavor mixing
patterns have been discussed. The observation of the neutrino oscillation at
CHORUS and NOMAD presents us the important constraint for the structure of the
neutrino flavor mixing matrix. The atomospheric neutrino anomaly has been
discussed in relation to the CHORUS and NOMAD experiments.


title: Dynamical Symmetry Breaking with Large Anomalous Dimension

abstract:
  We give an introduction to the dynamical symmetry breaking with large
anomalous dimension. This is the basis of tightly bound composite Higgs models
such as walking technicolor, strong ETC technicolor and top quark condensate,
which are all characterized by the large anomalous dimension, \gamma_m \simeq 1
(walking technicolor), 1<\gamma_m<2 (strong ETC technicolor) and \gamma_m
\simeq 2 (top quark condensate) due to nontrivial short distance dynamics of
the gauged Nambu-Jona-Lasinio (NJL) models (gauge theories plus four-fermion
interactions). Particular emphasis will be placed on the top quark condensate
in which the critical phenomenon in the gauged NJL model yields a simple reason
why the top quark can have an extremely large mass compared with other quarks
and leptons. Topics will also cover a recent observation that the four-fermion
theory {\it in the presence of gauge interactions} (gauged NJL model) can
become renormalizable and nontrivial in sharp contrast to the pure NJL model
without gauge interactions. The requirement of this
renormalizability/nontriviality of the gauged NJL model can be applied to the
top quark condensate when the standard gauge groups are unified into a GUT with
``walking'' coupling, which then naturally leads to the top quark and the Higgs
masses both around 180 GeV.


title: Energy Conservation Constraints on Multiplicity Correlations in QCD Jets

abstract:
  We compute analytically the effects of energy conservation on the
self-similar structure of parton correlations in QCD jets. The calculations are
performed both in the constant and running coupling cases. It is shown that the
corrections are phenomenologically sizeable. On a theoretical ground, energy
conservation constraints preserve the scaling properties of correlations in QCD
jets beyond the leading log approximation.


title:
Simple-minded estimate of the masses of baryons containing single heavy
  quarks

abstract:
  The masses of the yet undiscovered baryons containing single $c$ or $b$
quarks are estimated from the known masses using the following rules: equal
distances in mass between the isomultiplets forming sextets, equal mass
differences between the corresponding spin one-half baryons containing $c$ and
$b$ quarks, hyperfine splittings inversely proportional to the masses of the
heavy quarks.


title:
Unitarity Bounds in the Vector Condensate Model of Electroweak
  Interactions

abstract:
  We replace the standard model scalar doublet by a doublet of vector fields
and generate masses by dynamical symmetry breaking. Oblique radiative
corrections are small if the new vector bosons ($ B^+$, $ B^0 $) are heavy. In
this note it is shown that the model has a low momentum scale and above $
\Lambda \simeq 2 $ TeV it does not respect the perturbative unitarity. From
tree-graph unitarity the allowed region of $B ^+ (B^0) $ mass is estimated as
$m_{B^+} \geq 369 \hbox{GeV} \quad (m_{B^0} \geq 410 $ GeV) at $\Lambda= 1 $
TeV.


title: A Strong Electroweak Sector at Future Linear Colliders

abstract:
  An effective lagrangian describing a strong interacting electroweak sector is
considered. It contains new vector and axial-vector resonances all degenerate
in mass and mixed with $W$ and $Z$. The model, for large mass of these
degenerate gauge bosons, becomes identical to the standard model in the
classical limit of infinite Higgs mass. The limits on the parameter space of
this model from future $e^+e^-$ colliders are presented.


title: Improved Constraints on $B \to \pi\ell \bar\nu_{\ell}$ Form Factors

abstract:
  The behavior of the $\bpi$ form factors in the entire physical range is
examined in a model independent way. Unitarity bounds are further constrained
by the lattice results (APE). From this analysis, we obtain $f^{+}(0) = 0.38
\pm .03$ if the $B^{*}$-pole dominance behavior is assumed. However, to get the
information on the behavior of the form factor $f^{+}$, QSR results are
included. We see the deviations from the pole dominance due to the
contributions of the higher singularities which are to be treated
  with more precise lattice data.


title: Initial State of Disoriented Chiral Condensate Formation

abstract:
  It is unlikely to reach at high temperatures the state which is used as the
starting point of DCC formation in the quenched approximation. The chiral
symmetry is restored in the linear sigma model by Goldstone modes (pions),
because such isospin-p-wave states carry more entropy. In this paper we
estimate this effect of isospin-angular motion in the mean field approximation
assuming equipartition of the energy.


title:
Simulation of the process $e^+ e^- \mapsto e^+ e^- \gamma$ within
  electroweak theory with longitudinally polarized initial electrons

abstract:
  We present simple analytic expressions for the distributions of the Bhabha
scattering process with emission of one hard photon, including weak boson
exchanges, and with longitudinal polarization of the initial electron. The
results from the Monte Carlo generator BHAGEN-1PH, based on these expressions,
are presented and compared, for the unpolarized case, with those existing in
literature.


title: Singlets in Supersymmetry

abstract:
  It is argued that singlet extensions of the MSSM at the weak scale are
indicative of either gauged-$R$ symmetry or target space duality in a string
effective action at the Planck scale. The criteria used are satisfactory
primordial nucleosynthesis, absence of fine-tuning, and absence of cosmological
problems such as domain walls. Models which have a global discrete symmetry
such as the NMSSM may only be accommodated within rather complicated
cosmological scenarios which are also discussed.


title: Next to Leading Order Semi-inclusive Spin Asymmetries

abstract:
  We have computed semi-inclusive spin asymmetries for proton and deuteron
targets including next to leading order (NLO) QCD corrections and contributions
coming from the target fragmentation region. These corrections have been
estimated using NLO fragmentation functions, parton distributions and also a
model for spin dependent fracture functions which is proposed here. We have
found that NLO corrections are small but non-negligible in a scheme where
gluons are polarised and that our estimate for target fragmentation effects
does not modify significantly charged asymmetries but affects the so called
difference asymmetries.


title: Anomalous Processes in Effective Chiral Theories at High Temperatures

abstract:
  We discuss chiral theories of constituent quarks interacting with bosons at
high temperatures. In the chirally symmetric phase we demonstrate by applying
functional methods the presence of effective anomalous couplings for e.g. $\pi
\sigma \to \gamma \gamma, ~ \gamma \to \pi \pi \pi \sigma, ~K K \to \pi \pi \pi
\sigma$, etc., as they have recently been discussed by Pisarski.


title:
The Strange Sea Density and Charm Production in Deep Inelastic Charged
  Current Processes

abstract:
  Charm production as related to the determination of the strange sea density
in deep inelastic charged current processes is studied predominantly in the
framework of the $\overline{{\rm{MS}}}$ fixed flavor factorization scheme.
Perturbative stability within this formalism is demonstrated. The compatibility
of recent next-to-leading order strange quark distributions with the available
dimuon and $F^{\nu N}_2$ data is investigated. It is shown that final
conclusions concerning these distributions afford further analyses of presently
available and/or forthcoming neutrino data.


title:
Fully differential heavy quark contributions to the photon structure
  functions $F_{2}^{\gamma}(x,Q^2)$ and $F_{L}^{\gamma}(x,Q^2)$ at
  next-to-leading order QCD

abstract:
  Fully differential heavy quark contributions to the photon structure
functions in deeply inelastic scattering are computed in next-to-leading order
QCD, including both the direct and resolved contributions. A variety of
distributions are presented and discussed. Several of the distributions show
marked differences between the resolved and direct cases due primarily to the
presense of the gluon distribution in the former and lack thereof in the later.


title:
Hyperon Non-leptonic Decays, the |Delta I|=1/2 Rule, and A Priori Mixed
  Hadrons

abstract:
  The $|\Delta I|=1/2$ rule in non-leptonic decays of hyperons can be naturally
understood by postulating a priori mixed physical hadrons, along with the
isospin invariance of the responsible transition operator. It is shown that
this operator can be identified with the strong interaction Yukawa hamiltonian.
The experimental amplitudes are well reproduced.


title: Physics Beyond the Standard Model

abstract:
  We discuss some of the signatures associated with extensions of the Standard
Model related to the neutrino and electroweak symmetry breaking sectors, with
and without supersymmetry. The topics include a basic discussion of the theory
of neutrino mass and the corresponding extensions of the Standard Model that
incorporate massive neutrinos; an overview of the present observational status
of neutrino mass searches, with emphasis on solar neutrinos, as well the as
cosmological data on the amplitude of primordial density fluctuations; the
implications of neutrino mass in cosmological nucleosynthesis, non-accelerator,
as well as in high energy particle collider experiments. Turning to the
electroweak breaking sector, we discuss the physics potential for Higgs boson
searches at LEP200, including Majoron extensions of the Standard Model, and the
physics of invisibly decaying Higgs bosons. We discuss the minimal
supersymmetric Standard Model phenomenology, as well as some of the laboratory
signatures that would be associated to models with R parity violation,
especially in Z and scalar boson decays.


title: Dirac spectrum in QCD and Quark Masses

abstract:
  We use a chiral random matrix model to investigate the effects of massive
quarks on the distribution of eigenvalues of QCD inspired Dirac operators.
Kalkreuter's lattice analysis of the spectrum of the massive (hermitean) Dirac
operator for two colors and Wilson fermions is shown to follow from a cubic
equation in the quenched approximation. The quenched spectrum shows a
Mott-transition from a (delocalized) Goldstone phase softly broken by the
current mass, to a (localized) heavy quark phase, with quarks localized over
their Compton wavelength. Both phases are distinguishable by the quark density
of states at zero virtuality, with a critical quark mass of the order of
100-200 MeV. At the critical point, the quark density of states is given by
$\nu_Q (\lambda) \sim |\lambda|^{1/3}$. Using Grassmannian techniques, we
derive an integral representation for the resolvent of the massive Dirac
operator with one-flavor in the unquenched approximation, and show that near
zero virtuality, the distribution of eigenvalues is quantitatively changed by a
non-zero quark mass. The generalization of our construction to arbitrary
flavors is also discussed. Some recommendations for lattice simulations are
suggested.


title: Radiative Seesaw Mechanism at Weak Scale

abstract:
  We investigate an alternative seesaw mechanism for neutrino mass generation.
Neutrino mass is generated at loop level but the basic concept of usual seesaw
mechanism is kept. One simple model is constructed to show how this mechanism
is realized. The applications of this seesaw mechanism at weak scale to
cosmology and neutrino physics are discussed.


title: Chargino Mass and $R_b$ Anomaly

abstract:
  We re-examine the possible magnitude of the supersymmetric contribution to
$R_b$ with imposed all available phenomenological constraints and demanding
good quality of the global fit to the precision electroweak data. For low
$\tan\beta$ we find a new region of the parameter space, with $M_2\approx
|\mu|$ and $\mu<0$ where $R_b$ remains large, $\sim0.2180$ even for the lighter
chargino as heavy as $90-100$ GeV. It is an interesting mixture of the
up-higgsino and gaugino. The r\^ole of various phenomenological constraints is
discussed in analitic form and importance of small but non-negligible
left-right mixing in the stop sector is emphasized in this context. The large
$\tan\beta$ option for enhancement of $R_b$ is also reviewed. The available
data do not rule out this scenario.


title: New Strong Interactons at the Tevatron ?

abstract:
  Recent results from CDF indicate that the inclusive cross section for jets
with $E_T > 200$ GeV is significantly higher than that predicted by QCD. We
describe here a simple flavor-universal variant of the ``coloron" model of Hill
and Parke that can accommodate such a jet excess, and which is not in
contradiction with other experimental data. As such, the model serves as a
useful baseline with which to compare both the data and other models proposed
to describe the jet excess. An interesting theoretical feature of the model is
that if the global chiral symmetries of the quarks remain unbroken in the
confining phase of the coloron interaction, it realizes the possibility that
the ordinary quarks are composite particles.


title:
Test of QEDPS: A Monte Carlo for the hard photon distributions in e+ e-
  annihilation proecss

abstract:
  The validity of a photon shower generator QEDPS has been examined in detail.
This is formulated based on the leading-logarithmic renormalization equation
for the electron structure function and it provides a photon shower along the
initial e+-. The main interest in the present work is to test the reliability
of the generator to describe a process accompanying hard photons which are
detected. For this purpose, by taking the HZ production as the basic reaction,
the total cross section and some distributions of the hard photons are compared
between two cases that these photons come from either those generated by QEDPS
or the hard process e+e- -> H Z gamma gamma. The comparison performed for the
single and the double hard photon has shown a satisfactory agreement which
demonstrated that the model is self-consistent.


title: Double Bubble Corrections to Heavy Quark Production

abstract:
  Second order ${\cal O}(\alpha_s^2)$ corrections to the heavy quark production
cross-section due to massless quarks and coloured scalars are calculated for
all energies above threshold. Based on the method introduced in this letter
also the gauge non-invariant second order corrections due to the pure gluonic
selfenergy insertion and a certain class of ${\cal{O}}(\alpha_s^3)$ and
${\cal{O}}(\alpha_s^4)$ corrections are determined. For the special choice of
the gauge parameter, $\xi=4$, the leading threshold and high energy behaviour
of the pure second order gluonic corrections to the cross-section are governed
by the gluonic self energy insertion.


title:
Implications of the $B \to X \ell \bar\nu_\ell$ lepton spectrum for
  heavy quark physics

abstract:
  The shape of the lepton spectrum in inclusive semileptonic $B\to
X\,\ell\,\bar\nu_\ell$ decay is sensitive to matrix elements of the heavy quark
effective theory, $\bar\Lambda$ and $\lambda_1$. From CLEO data we extract
$\bar\Lambda=0.39\pm0.11\,$GeV and $\lambda_1=-0.19\pm0.10\,{\rm GeV}^2$, where
the uncertainty is the $1\sigma$ statistical error only. Systematic
uncertainties are discussed. These values for $\bar\Lambda$ and $\lambda_1$ are
used to determine $|V_{cb}|$ and the $\overline{\rm MS}$ bottom and charm quark
masses. We discuss the theoretical uncertainties related to order
$(\Lambda_{\rm QCD}/m_b)^3$ effects and higher orders in the perturbative
expansion.


title: Developments in Perturbative QCD: Challenges from Collider Physics

abstract:
  The search for new phenomena at hadron colliders requires a good
understanding of QCD processes. The analysis of multi-jet signatures in the top
quark search at the Tevatron is one example, forward jet-tagging and rapidity
gap techniques in the analysis of weak boson scattering events at the LHC will
be another important application. These topics are discussed in the context of
multi-parton/multi-jet QCD processes. Also described are some of the
calculational tools, like amplitude techniques and automatic code generation
for tree level processes.


title: Theorem on the Lightest Glueball State

abstract:
  This paper is devoted to proving that, in QCD, the lightest glueball state
must be the scalar with $J^{PC} = 0^{++}$. The proof relies upon the positivity
of the path integral measure in Euclidean space and the fact that interpolating
fields for all spins can be bounded by powers of the scalar glueball operator.
The problem presented by the presence of vacuum condensates is circumvented by
considering the time evolution of the propagators and exploiting the positivity
of the Hamiltonian.


title: Restriction to Parametric Resonant Decay after Inflation

abstract:
  We study parametric resonant decay of inflaton field with emphasis on its
physical meaning. We show that the parametric resonance is indeed an induced
process, which means that the more numbers of produced particles, the more
inflaton field decays. We also consider the dissipative effects of produced
particles and find that the dissipation reduces the resonant decay rate of
inflaton field.


title:
CP-Violation in the Decay $b \to s\gamma$ in the Left-Right Symmetric
  Model

abstract:
  The direct CP-violation in the left-right symmetric $SU(2) \times SU(2)
\times U(1)$ model is investigated for the decay $b \rightarrow s\gamma$. The
calculated CP-asymmetry for the wide range of parameters can be larger than in
standard model and can have an opposite sign.


title: Polarization asymmetry and the Higgs boson production mechanisms

abstract:
  We calculate the cross section of Higgs boson production in the reaction e+e-
-> neutrino anti-neutrino b b-bar for the case of left and right longitudinally
polarized electron beam. Complete set of signal and irreducible background
diagrams is considered.
  We propose a new critical test to identify the Higgs boson provided by the
ratio of cross sections with left and right beam polarization. This quantity is
sensitive to the ratio of Higgs-W and Higgs-Z couplings, since it exhibits the
interplay of bremsstrahlung and fusion mechanisms of Higgs boson production
inherent to the Standard Model scheme.


title: Higgs decay into two photons, dispersion relations and trace anomaly

abstract:
  We examine the contribution of W boson loops to the amplitude of the process
H --> \gamma \gamma within the dispersion relation approach, taking up an issue
raised in this context recently. We show that the non-vanishing limit of the
relevant formfactor for mW --> 0 is due to a finite subtraction induced by the
value of the corresponding trace anomaly. The argument can be truned around and
one thus arrives at a dispersive ("infrared") derivation of the trace anomaly.


title: Electroweak interactions and high-energy limit

abstract:
  A pedagogical introduction to the equivalence theorem for longitudinal vector
bosons in electroweak theories is presented and the problem of high-energy
behaviour of scattering amplitudes in the Standard Model is briefly reviewed.
To make the treatment self-contained, the basics of the Standard Model are
summarized in an appendix.


title: Improved QEDPS for Radiative Corrections in e+e- Annihilation

abstract:
  The generator QEDPS, a parton shower model in QED, developed by the present
authors has been improved. By a careful study on the shower algorithm it was
found that some finite contributions have been missed in the original version.
They are small, but cannot be neglected when the contribution of the soft
photons is dominant. A method is presented to correct these finite pieces and
then a new generator, improved QEDPS, is proposed, which is able to make more
precise prediction for the processes observed in e+e- annihilation as far as
the initial radiation is concerned.


title: A general treatment of oblique parameters

abstract:
  A reexamination is made of one-loop oblique electroweak corrections. General
definitions are given of the oblique parameters without reference to any
$q^2$-expansion scheme. The old oblique parameters S,T and U are defined as
differences of gauge boson vacuum polarization $\Pi$-functions and suffice to
describe certain observable ratios on the Z-peak and the $\rho$ parameter at
$q^2=0$. Regarding the new oblique parameters V,W and X, the first two are
defined in terms of differences of $\Pi$-functions as well as the wavefunction
renormalization of the corresponding weak boson, and the third in terms of the
difference of differences of two $\Pi$-functions for $\gamma-Z$ mixing.
Explicit expressions for measurable quantities involving all six oblique
parameters are given and experimental bounds are obtained on the latter, some
for the first time. A review of these constraints suggests that the linear
approximation of Peskin and Takeuchi is robust.


title: Affleck-Dine Baryogenesis after Thermal Inflation

abstract:
  We argue that an extension of the Minimal Supersymmetric Standard Model that
gives rise to viable thermal inflation, and so does not suffer from a
Polonyi/moduli problem, should contain right-handed neutrinos which acquire
their masses due to the vacuum expectation value of the flaton that drives
thermal inflation. This strongly disfavours SO(10) Grand Unified Theories. The
$\mu$-term of the MSSM should also arise due to the vev of the flaton. With the
extra assumption that $ m_L^2 - m_{H_u}^2 < 0 $, but of course $ m_L^2 -
m_{H_u}^2 + |\mu|^2 > 0 $, we show that a complicated Affleck-Dine type of
baryogenesis employing an $LH_u$ $D$-flat direction can naturally generate the
baryon asymmetry of the Universe.


title: Cutting rules at finite temperature

abstract:
  We discuss the cutting rules in the real time approach to finite temperature
field theory and show the existence of cancellations among classes of cut
graphs which allows a physical interpretation of the imaginary part of the
relevant amplitude in terms of underlying microscopic processes. Furthermore,
with these cancellations, any calculation of the imaginary part of an amplitude
becomes much easier and completely parallel to the zero temperature case.


title:
The Perturbative Resummed Series for Top Quark Production in Hadron
  Reactions

abstract:
  Our calculation of the total cross section for inclusive production of
$t\bar{t}$ pairs in hadron collisions is presented. The principal ingredient of
the calculation is resummation of the universal leading-logarithm effects of
gluon radiation to all orders in the quantum chromodynamics coupling strength,
restricted to the region of phase space that is demonstrably perturbative. We
derive the perturbative regime of the resummed series, starting from the
principal-value resummation approach, and we isolate the perturbative domain in
both moment space and, upon inversion of the corresponding Mellin transform, in
momentum space. We show that our perturbative result does not depend on the
manner non-perturbative or infrared effects are handled in principal-value
resummation. We treat both the quark-antiquark and gluon-gluon production
channels consistently in the $\overline{{\rm MS}}$ factorization scheme. We
compare our method and results with other resummation methods that rely on the
choice of infrared cutoffs. We derive the renormalization/factorization scale
dependence of our resummed cross section, and we discuss factorization scheme
dependence and remaining theoretical uncertainties, including estimates of
possible non-perturbative contributions. We include the full content of the
exact next-to-leading order calculation in obtaining our final results. We
present predictions of the physical cross section as a function of top quark
mass in proton-antiproton reactions at center-of-mass energies of 1.8 and 2.0
TeV. We also provide the differential cross section as a function of the
parton-parton subenergy.


title: Can partons describe the CDF jet data?

abstract:
  The recent CDF single jet inclusive measurements at Fermilab are incorporated
in a global next-to-leading order parton analysis of the available deep
inelastic and related data. We find that it is impossible to achieve a
simultaneous QCD description of both the CDF jet distribution for transverse
energies $E_T > 200$~GeV and the deep inelastic structure function data for $x
> 0.3$. However, the CDF data for $E_T < 200$~GeV and the deep inelastic data
are adequately described provided that the QCD coupling $\alpha_S(M_Z^2)$ is
increased from its preferred deep inelastic value to $\alpha_S (M_Z^2) \simeq
0.116 - 0.120$.


title:
Resonant CP-Violating Scalar--Pseudoscalar Transitions at mu+ mu-
  Colliders

abstract:
  A mu+ mu- collider is an appealing machine to probe resonant CP-violating
transitions of a CP-even Higgs particle into the Z boson or into another CP-odd
Higgs scalar. These phenomena are studied within a manifestly gauge-invariant
approach implemented by the pinch technique. The CP invariance of an extended
Higgs sector motivated by supersymmetric E_6 models is assumed to be broken
radiatively by the presence of heavy Majorana fermions. CP violation
originating from Higgs-Z mixing is found to be very modest, whereas CP-number
violating transitions involving Higgs scalars only can be resonantly enhanced
up to order of unity.


title: Signals from supersymmetry in electroweak precision data?

abstract:
  The predictions of the \sm and the minimal supersymmetric standard model
(MSSM) for the electroweak precision parameters are discussed in the light of
the recent precision data. The results from global fits yield lower $\chi^2$
values in the MSSM than in the Standard model. The fits prefer regions in the
MSSM parameter space with $M_2 \simeq |\mu| $ and allow chargino masses higher
than the present exclusion limits of LEP 1.5.


title:
The perturbative pion-photon transition form factors with transverse
  momentum corrections

abstract:
  We perform a perturbative QCD analysis of the quark transverse momentum
effect on the pion-photon transition form factors $F_{\pi \gamma}$ and $F_{\pi
\gamma^*}$ in the standard light-cone formalism, with two phenomenological
models of wavefunction as the input of the non-perturbative aspect of the pion.
We point out that the transverse momentum dependence in both the numerator and
the denominator of the hard scattering amplitude is of the same importance and
should be considered consistently. It is shown that after taking into account
the quark transverse momentum corrections, the results obtained from different
model wave function are consistent with the available experimental data at
finite $Q^2$.


title: Some Remarks on the Search for CP Violation in Z-Decays

abstract:
  We discuss some issues arising in the search for CP violation in the decays Z
-> tau+ tau- and Z -> b \bar b X. The form-factor and the effective Lagrangian
approach to parametrize CP-violating effects are compared. We emphasize the
interest to study both real and imaginary parts of CP-violating form factors
like the weak dipole moment form factor d_tau^Z(m^2_Z) of the tau-lepton. We
propose an 'optimal' way to search for CP violation when Z -> b \bar b X events
have to be selected on a statistical basis from the total number of Z hadronic
decays.


title: Issues in Heavy Flavour Baryons

abstract:
  I present a mini-review on the physics of heavy flavour baryons where I
concentrate on the HQET description of their exclusive decay modes. In
particular I discuss the structure of current-induced bottom baryon to charm
baryon transitions, and the structure of pion and photon transitions between
heavy charm or bottom baryons in the Heavy Quark Symmetry limit as m_Q->\infty.
The emphasis is on the structural similarity of the Heavy Quark Symmetry
predictions for the three types of transitions. The requisite coupling
expressions are discussed both in the covariant framework as well as in terms
of Clebsch-Gordan coefficients and 6-j symbols. At the end of my review I touch
on some unresolved issues in exclusive nonleptonic charm and bottom baryon
decays which serve to highlight our present lack of understanding of
nonleptonic heavy baryon decays.


title: Spin-Spin Correlations of Top Quark Pairs at Hadron Colliders

abstract:
  Top quark pairs are produced with strongly correlated spins in the partonic
reactions $q\bar{q}\to t\bar{t}$ and $gg\to t\bar{t}$. A complete description
of these effects in terms of the spin density matrix of the $t\bar{t}$ system
in leading order QCD is given. We further discuss the prospects to observe the
spin-spin correlations at $p\bar{p}$ and $pp$ colliders by measuring suitable
angular correlations among the $t$ and $\bar{t}$ decay products.


title: Approximate flavor symmetries at a grand unification scale

abstract:
  We study the evolution of fermion mass matrices considering the hypothesis of
approximate flavor symmetries (AFS) in the Standard Model and a
two-Higgs-doublet model. We find that the hierarchical structure is not
significantly altered by the running, hence the assumption of AFS is entirely
compatible with a grand unification scenario.


title:
Three Flavour Gravitationally Induced Neutrino Oscillations and the
  Solar Neutrino Problem

abstract:
  Some implications of the proposal that flavor nondiagonal couplings of
neutrinos to gravity might resolve the solar neutrino problem are considered in
the context of three neutrino flavors. The two--flavor model is discussed as a
limiting case of the full three-generation mechanism, and the behavior of the
$\nue$ survival probability for various values of the three--flavor parameters
is studied. Overlapping allowed SNU regions are obtained for the neutrinos
which most likely contribute to the observed solar neutrino deficiency, and the
effects of the addition of a third flavor are discussed. The extension to a
three--generation framework is found to yield a greater allowed region of
parameter space, suggesting that gravitationally--induced neutrino oscillations
remain a viable explanation of the Solar Neutrino Problem.


title: Higgsino Cold Dark Matter Motivated by Collider Data

abstract:
  Motivated by the supersymmetric interpretation of the CDF ee\gamma\gamma plus
missing energy event and the reported Z->bb excess at LEP, we analyze the
Higgsino as a cold dark matter candidate. We examine the constraints as implied
by the collider experiments, and then calculate its relic density. We find that
this Higgsino-like lightest supersymmetric particle is a viable cold dark
matter candidate (0.05 < Omega h^2 < 1), and we discuss its favorable prospects
for laboratory detection.


title:
The gauge invariant effective potential: equilibrium and non-equilibrium
  aspects

abstract:
  We propose a gauge invariant formulation of the effective potential in terms
of a gauge invariant order parameter, for the Abelian Higgs model. The one-loop
contribution at zero and finite temperature is computed explicitly, and the
leading terms in the high temperature expansion are obtained. The result is
contrasted to the effective potential obtained in several covariant
gauge-fixing schemes, and the gauge invariant quantities that can be reliably
extracted from these are identified. It is pointed out that the gauge invariant
effective potential in the one-loop approximation is complex for {\em all
values} of the order parameter between the maximum and the minimum of the tree
level potential, both at zero and non-zero temperature. The imaginary part is
related to long-wavelength instabilities towards phase separation. We study the
real-time dynamics of initial states in the spinodal region, and relate the
imaginary part of the effective potential to the growth rate of equal-time
gauge invariant correlation functions in these states. We conjecture that the
spinodal instabilities may play a role in non-equilibrium processes {\em
inside} the nucleating bubbles if the transition is first order.


title:
Renormalization of Twist-4 Operators in QCD Bjorken and Ellis-Jaffe Sum
  Rules

abstract:
  The QCD effects of twist-4 operators on the first moment of nucleon
spin-dependent structure function $g_1(x, Q^2 )$ are studied in the framework
of operator product expansion and renormalization group method. We investigate
the operator mixing through renormalization of the twist-4 operators including
those proportional to the equation of motion by evaluating off-shell Green's
functions in the usual covariant gauge as well as in the background gauge.
Through this procedure we extract the one-loop anomalous dimension of the spin
1 and twist-4 operator which determines the logarithmic correction to the
$1/Q^2$ behavior of the contribution from the twist-4 operators to the first
moment of $g_1(x,Q^2)$.


title: Damping Rate and Lyapunov Exponent of a Higgs Field at High Temperature

abstract:
  The damping rate of a Higgs field at zero momentum is calculated using the
Braaten-Pisarski method and compared to the Lyapunov exponent of the classical
SU(2) Yang-Mills Higgs system.


title: Semileptonic decays $B\to(\pi,\rho)e\nu$ in relativistic quark model

abstract:
  Quark model results for the $B\to \pi,\rho$ decays are analysed, making use
of the dispersion formulation of the model: The form factors at $q^2>0$ are
expressed as relativistic invariant double spectral representation over
invariant masses of the initial and final mesons through their light--cone wave
functions. The dependence of the results on the quark model parameters is
studied. For various versions of the quark model the ranges $\Gamma(\bar
B^0\to\pi^+e\bar\nu)=(7\pm2)\times10^{12}|V_{ub}|^2\; s^{-1}$, $\Gamma(\bar
B^0\to\rho^+e\bar\nu)/\Gamma(\bar B^0\to\pi^+e\bar\nu)=1.45\pm0.1$, and
$\Gamma_L/\Gamma_T=0.7\pm0.08$ are found. The effects of the constituent quark
transition form factor are briefly discussed.


title:
Dyson summation without violating Ward identities and the
  Goldstone-boson equivalence theorem

abstract:
  In contrast to the conventional treatment of gauge theories, in the
background-field method the Ward identities for connected Green functions are
not violated by Dyson summation of self-energies in finite orders of
perturbation theory. Thus, Dyson summation does not spoil gauge cancelations at
high energies which are ruled by the Goldstone-boson equivalence theorem.
Moreover, in the background-field method the precise formulation of the
equivalence theorem in higher orders (including questions of renormalization)
is simplified rendering actual calculations easier. Finally, the equivalence
theorem is also formulated for the Standard Model with a non-linearly realized
scalar sector and for the gauged non-linear $\sigma$-model.


title: Searching for Relic Neutralinos using Neutrino Telescopes

abstract:
  Neutrino telescopes of large area offer the possibility of searching for
indirect signals of relic neutralinos in the galactic halo, due to
annihilations in the Sun or the Earth. Here we investigate the sensitivity,
using a supergravity scheme where the soft scalar mass terms are not
constrained by universality conditions at the grand unification scale. We first
discuss in which regions of the supersymmetric parameter space the neutralino
may be considered as a good candidate for cold dark matter. The discovery
potential of the search using neutrino telescopes is then compared to that of
the direct search for relic neutralinos.


title: Anomalous Higgs Boson Contribution to e^+ e^- \to b \bbar \gamma at LEP2

abstract:
  We study the effect of anomalous $H\gamma\gamma$ and $HZ\gamma$ couplings,
described by a general effective Lagrangian, on the process $e^+ e^- \to b
\bar{b} \gamma $ at LEP2 energies. We include the relevant irreducible standard
model background to this process, and from the photon energy spectrum, we
determine the reach of LEP2 to unravel the anomalous couplings by analyzing the
significance of the signal for Higgs boson with mass up to $150$ GeV.


title:
Dynamical O(alpha_s) Effects in Forward-Backward Asymmetries of Heavy
  Quarks

abstract:
  We examine the O(alpha_s) forward-backward asymmetries for the production
process e+ e- --> gamma,Z --> q qbar (g), tagging the outgoing heavy-quark jet
at center-of-momentum energies off the Z-peak. The complicated analytic results
are reduced to simple polynomial forms that provide excellent approximations.
For charm and bottom quark, a full dynamical cancellation gives O(alpha_s)
zeros in the forward-backward asymmetry close to the Z-peak. We conclude with a
detailed numerical analysis of our results.


title: Radiative Four--Meson Amplitudes in Chiral Perturbation Theory

abstract:
  We present a general discussion of radiative four--meson processes to
$O(p^4)$ in chiral perturbation theory. We propose a definition of
``generalized bremsstrahlung'' that takes full advantage of experimental
information on the corresponding non--radiative process. We also derive general
formulae for one--loop amplitudes which can be applied, for instance, to $\eta
\ra 3\pi\gamma$, $\pi \pi \ra \pi \pi \gamma$ and $K \ra 3\pi\gamma$.


title:
MSSM Predictions of the neutral Higgs boson masses and LEP II production
  cross sections

abstract:
  Within the framework of the Minimal Supersymmetric Standard Model (MSSM) the
Higgs masses and LEP II production cross sections are calculated for a wide
range of the parameter space. In addition, the parameter space restricted by
unification, electroweak symmetry breaking and other low energy constraints is
considered in detail, in which case the masses of all SUSY partners can be
estimated, so that their contributions to the radiative corrections can be
calculated. Explicit analytical formulae for these contribution are derived.
  The radiative corrections from the Yukawa couplings of the third generation
are found to dominate over the contributions from charginos and neutralinos.
  Large Higgs mass uncertainties are due to the top mass uncertainty and the
unknown sign of the Higgs mixing parameter. For the low tanb scenario the mass
of the lightest Higgs is found to be below 103 GeV for a top mass below 190
GeV. The cross section at a LEP energy of 192 GeV is sufficient to find or
exclude this low tanb scenario for a top mass below 180 GeV. For the high tanb
scenario only a small fraction of the parameter space can be covered, since the
Higgs mass is predicted between 105 and 125 GeV in most cases. At the
theoretically possible LEP II energy of 205 GeV part of the parameter space for
the large tanb scenario would be accessible.


title: Search for New Neutral Bosons at Future Colliders

abstract:
  This is a short review of present and future limits on new neutral gauge
bosons, in particular on hadrophilic or leptophobic $Z'$s recently proposed to
interpret the observed fluctuations of $\Gamma _{c,b}$ at LEP. Light gauge
bosons coupled to lepton number differences or to baryon number are also
examples of the model dependence of these bounds. The mixing between the $U(1)$
factors plays an important role in the phenomenology of these extended
electroweak models. Future improvements based on the analysis of precise
electroweak data are emphasized.


title: QCD-Inspired Spectra from Blue's Functions

abstract:
  We use the law of addition in random matrix theory to analyze the spectral
distributions of a variety of chiral random matrix models as inspired from QCD
whether through symmetries or models. In terms of the Blue's functions recently
discussed by Zee, we show that most of the spectral distributions in the
macroscopic limit and the quenched approximation, follow algebraically from the
discontinuity of a pertinent solution to a cubic (Cardano) or a quartic
(Ferrari) equation. We use the end-point equation of the energy spectra in
chiral random matrix models to argue for novel phase structures, in which the
Dirac density of states plays the role of an order parameter.


title: A Model of Strong Flavor Dynamics for the Top Quark

abstract:
  We discuss a model in which the third generation fermions undergo a different
$SU(2)$ weak interaction from the first two generation fermions. In general, a
flavor changing neutral current interaction is expected. Constrained by the
precision low energy data, the mass ($M_{Z'}=M_{W'}$) of the heavy gauge bosons
is bounded from below to be about $1.1$ TeV for $\alpha_s=0.125$ and about
$1.3$ TeV for $\alpha_s=0.115$, at the $3\sigma$ level. This model favors a
larger $R_b$ and a smaller $R_c$ as compared with the Standard Model, but it
does not explain the $R_c$ data. If one takes the $R_b$ data seriously, then
$M_{Z'}$ is bounded, at the $3\sigma$ level, to be $462$ GeV $< M_{Z^{\prime}}
\cos\phi < 1481\,\, {\rm{GeV}}$, where $\cos\phi$ is the mixing angle between
the two $SU(2)$'s in the model. Effects predicted for high energy experiments
at the Tevatron, LEP140, LEP-II, LHC, and future linear colliders are also
discussed.


title:
Combined Fit of Low Energy Constraints to Minimal Supersymmetry and
  Discovery Potential at LEP II

abstract:
  Within the Constrained Minimal Supersymmetric Standard Model it is possible
to predict the low energy gauge couplings and masses of the 3. generation
particles from a few parameters at the GUT scale. In addition the MSSM predicts
elektroweak symmetry breaking due to large radiative corrections from Yukawa
couplings, thus relating the Z^0 boson mass to the top quark mass. From a
\chi^2 analysis, in which these constraints can be considered simultaneously,
one can calculate the probability for each point in the MSGUT parameter space.
Our fits include full second order corrections for the gauge and Yukawa
couplings, low energy treshold effects, contributions of all (s)particles to
the Higgs potential and corrections to m_b from qluinos and higgsinos, which
exclude (in our notation) positive values of the mixing parameter in the Higgs
potential \mu for the large tan \beta region. Further constraints can be
derived from the branching ratio for the radiative (penguin) decay of the
b-quark into s \gamma and the lower limit on the lifetime of the universe,
which requires the dark matter density due to the Lightest Supersymmetric
Particle (LSP) not to overclose the universe. For particles, which are most
likely to have masses in the LEP II energy range, the cross sections are given
for the various energy scenarios at LEP II. For low tan \beta the production of
the lightest Higgs boson, which is expected to have a mass below 103 GeV, is
the most promising channel, while for large tan \beta the production of
charginos and/or neutralinos covers the preferred parameter space.


title:
Gauge Invariance in the Process $e^+e^-\to \bar \nu_e e^-W^+\to\bar\nu_e
  e^-u\bar d$

abstract:
  The process $e^+e^-\rightarrow \bar \nu_e e^-W^+ \rightarrow\bar\nu_e
e^-u\bar d$ is considered as an example of the problems associated with
maintaining gauge invariance in matrix elements involving unstable particles.
It is shown how to construct a matrix element that correctly treats width
effects for the intermediate unstable $W$ boson and that is both $SU(2)_L$ and
$U(1)_{\rm e.m.}$ gauge-invariant. $SU(2)_L$ gauge-invariance is maintained by
Laurent expansion in kinematic invariants and $U(1)_{\rm e.m.}$
gauge-invariance is enforced by means of a projection operator under which the
exact matrix element is invariant.


title: Physical mechanism of the linear beam-size effect at colliders

abstract:
  We present qualitative but precise description of the linear beam-size effect
predicted for the processes in which unstable but long--living particles
collide with each other. We derive physically pronounced equation for the
events rate which proves that the linear beam-size effect corresponds to the
scattering of one beam of particles on the decay products of the other. We
compare this linear beam-size effect with the known logarithmic beam-size
effect measured in the experiments on a single bremsstrahlung at VEPP-4 and
HERA.


title: Efficacious Extra U(1) Factor for the Supersymmetric Standard Model

abstract:
  The totality of neutrino-oscillation phenomena appears to require the
existence of a light singlet neutrino. As pointed out recently, this can be
naturally accommodated with a specific extra U(1) factor contained in the
superstring-inspired E$_6$ model and its implied particle spectrum. We analyze
this model for other possible consequences. We discuss specifically the oblique
corrections from Z-Z' mixing, the phenomenology of the two-Higgs-doublet sector
and the associated neutralino sector, as well as possible scenarios of
gauge-coupling unification.


title: Why is a nucleon bound?

abstract:
  In a style of popular article, we discuss models of hadronic structure and
their relation with models of the QCD vacuum and lattice simulations. Borrowing
two main characters from G.Gamow, Mr.Thompson and Professor, we make a travel
in the QCD vacuum. Instanton-generated interaction between quarks appear to be
major player, they create quark condensate, constituent quark masses and their
bound states with properties very close to those observed. Direct removal of
perturbative and confining forces (possible on the lattice by ``cooling'')
result in very small modification of hadrons. Phase transitions at high T and
large number of quarks in the theory are discussed.


title: Semileptonic Decay of $B$-Meson into $D^{**}$ and the Bjorken Sum Rule

abstract:
  We study the semileptonic branching fraction of $B$-meson into higher
resonance of charmed meson $D^{**}$ by using the Bjorken sum rule and the heavy
quark effective theory(HQET). This sum rule and the current experiment of
$B$-meson semileptonic decay into $D$ and $D^*$ predict that the branching
ratio into $D^{**}l\nu_l$ is about 1.7\%. This predicted value is larger than
the value obtained by the various theoretical hadron models based on the HQET.


title: Decay Rate of Coherent Field Oscillation

abstract:
  In recent studies it has become increasingly clear that presence of
infinitely many instability bands of the parametric resonance plays crucial
roles in the phenomenon of particle production under periodic classical field
oscillation. We extend previous works to a general class of models including
both the Yukawa and the quartic type of couplings of the classical field to
quantum bose fields. Decay rate from the $n-$th band is derived in the small
amplitude limit using the functional Schr$\stackrel{..}{{\rm o}}$dinger
picture. It is then shown that this analytic result of the decay rate can also
be derived as the zero momentum limit of a physical process, $n$ particles that
comprise the classical homogeneous field decaying simultaneously into 2 bose
particles. The latter approach uses ordinary perturbation theory, hence the
former result is a novel resummation of many perturbative amplitudes, which
usually becomes complicated for a large $n$ order.


title:
Chiral Perturbation Theory Predictions for $\eta \to \pi^+ \pi^- \pi^0
  \gamma$

abstract:
  The $\eta \to \pi^+ \pi^- \pi^0 \gamma$ decay is discussed in the general
context of Chiral Perturbation Theory (ChPT), assuming that the low--energy
constants (counter--terms) are saturated by vector-meson resonances. The $\eta
\to \pi^+ \pi^- \pi^0 \gamma$ amplitude can be separated in two distinct
pieces: the inner bremsstrahlung, $A^{(IB)}$, and the structure dependent (or
direct emission), $A^{(SD)}$, amplitudes. The former -- which essentially
contains the same physics as $A(\eta \to \pi^+ \pi^- \pi^0)$ -- is found to
dominate over the second one -- which looks more interesting from the ChPT
point of view.


title: 1/N_c expansion for the partition function in four fermion models

abstract:
  We present a derivation of the bosonic contribution to the thermodynamical
potential of four fermion models by means of a $1/N_c$-expansion of the
functional integral defining the partition function. This expansion turns out
to be particularly useful to correct the mean field approximation expecially at
low temperatures, where the relevant degrees of freedom are low-mass bosonic
excitations (pseudogoldstones).


title: On Renormalons and Landau Poles in Gauge Field Theories

abstract:
  It is shown that the commonly accepted relationship between the Landau
singularity in the running coupling constant of QED or QCD and the renormalon
singularities in the Borel sums of perturbation theory expansions is only a
particular feature of the restriction of the perturbative $\beta$--function to
the one loop level.


title: The EMC effect at low x in perturbative QCD

abstract:
  The EMC effect is studied in the perturbative QCD hard pomeron approach. In
the limit $x\rightarrow 0$ and for a nucleus with a constant density the effect
is found to be a function of a single variable which combines its $x$-, $Q$-
and $A$-dependence. At large $Q^{2}$ the effect dies out as $\ln Q/Q$. At small
but finite $x$ a change in the anomalous dimension leads to a weaker
$Q$-dependence, which almost disappears as $x$ grows and the anomalous
dimension becomes small. In this approach the nuclear structure function can be
expressed directly in terms of the proton one. Calculations of the EMC effect
on these lines give results which agree reasonably well to the existing
experimental data for $x<0.05$.


title:
Deep inelastic events containing a forward photon as a probe of small
  $x$ dynamics

abstract:
  We calculate the rate of producing deep inelastic events containing an
energetic isolated forward photon at HERA. We quantify the enhancement arising
from the leading $\log 1/x$ gluon emissions with a view to using such events to
identify the underlying dynamics.


title: Trilinear Gauge Boson Couplings in the MSSM

abstract:
  We study the C and P even WW\gamma and WWZ trilinear gauge boson vertices
(TGV's), in the context of the MSSM assuming that the external W's are on their
mass shell. We find that for energies less than 200 GeV squark and slepton
contributions to the aforementioned couplings are two orders of magnitude
smaller than those of the Standard Model (SM). In the same energy range the
bulk of the supersymmetric Higgs corrections to the TGV's is due to the
lightest neutral Higgs, h_0, whose contribution is like that of a Standard
Model Higgs of the same mass. The contributions of the Neutralinos and
Charginos are sensitive to the input value for the soft gaugino mass M_{1/2},
being more pronounced for values M_{1/2} < 100 GeV. In this case and in the
unphysical region, 0 < \sqrt{s} < 2 M_W , their contributions are substantially
enhanced resulting in large corrections to the static quantities of the W
boson. However, such an enhancement is not observed in the physical region. In
general for 2 M_W < \sqrt{s} < 200 GeV the MSSM predictions differ from those
of the SM but they are of the same order of magnitude. To be detectable
deviations from the SM require sensitivities reaching the per mille level and
hence unlikely to be observed at LEP200. For higher energies SM and MSSM
predictions exhibit a fast fall off behaviour, in accord with unitarity
requirements, getting smaller,in most cases, by almost an order of magnitude
already at energies \sqrt{s} 0.5 TeV.


title: New Constraints On Lepton Nonconserving R-parity Violating Couplings

abstract:
  Strong upper bounds are derived on certain product combinations of lepton
nonconserving couplings in the minimal supersymmetric standard model with
explicit $R$-parity violation. The input is information from rare leptonic
decays of the long-lived neutral kaon, the muon and the tau as well as from the
mixings of neutral $K$- and $B$-mesons. One of these bounds is comparable and
another superior to corresponding ones obtained recently from neutrinoless
double beta decay.


title:
Tracing the origin of the single-spin asymmetries observed in inclusive
  hadron production processes at high energies

abstract:
  It is pointed out that the existing models for the left-right asymmetries
observed in single-spin inclusive hadron production processes can be
differentiated experimentally. Several such experiments are proposed with which
the basic assumptions of these models can be tested individually.


title: Temperature Shift of Neutrino Energy in the External Magnetic Field

abstract:
  It is evaluated the first order temperature correction to the energy of
massive neutrino in the case of weak magnetic field.