title: Fermion Masses without Higgs: A Supersymmetric Technicolor Model

abstract:
  We propose a supersymmetric technicolor model in which the electroweak
symmetry breaking is communicated to the quarks and leptons by technicolored
$SU(2)_W$-singlet scalars. When the technifermions condense, the quarks and
leptons of the third generation acquire mass. The fermions of the other
generations do not couple to the technicolored scalars but they receive masses
from radiative corrections involving superpartners. As a result, the mass
hierarchy between the fermion generations arises naturally. The model predicts
the CP asymmetries in $B$ meson decays and in $\Delta S = 1$ transitions to be
smaller by two orders of magnitude than the ones predicted in the Standard
Model.


title: Multiloop calculations in heavy quark effective theory

abstract:
  We review algorithmic methods for two-loop calculations in HQET, and the
analogous methods for on-shell QCD, needed for matching HQET to QCD.


title: Anomalous Gluon Self-Interactions and $t \bar{t}$ Production

abstract:
  Strong-interaction physics that lies beyond the standard model may
conveniently be described by an effective Lagrangian. The only genuinely
gluonic CP-conserving term at dimension six is the three-gluon-field-strength
operator $G^3$. This operator, which alters the 3-gluon and 4-gluon vertices
form their standard model forms, turns out to be difficult to detect in final
states containing light jets. Its effects on top quark pair production hold the
greatest promise of visibility.


title:
Conformally Symmetric Contributions to BFKL Evolution at Next to Leading
  Order

abstract:
  Unitarity corrections to the BFKL evolution at next to leading order
determine a new component of the evolution kernel which is shown to possess
conformal invariance properties. Expressions for the complete spectrum of the
new component and the correction to the intercept of the pomeron trajectory are
presented.


title: A New Physics Source of Hard Gluons in Top Quark Production

abstract:
  We consider the contribution of new strongly interacting sector, with a
characteristic scale of half a TeV, to top quark production at the Tevatron.
The color-octet, isosinglet analog of the $\rho$ meson in this theory is
produced copiously in hadron colliders. If the mass of this resonance is less
than twice the mass of the lightest pseudo-Goldstone bosons, then an important
decay mode could be to the color-octet analog of the $\eta$ and a gluon. The
subsequent decay of this $\eta$ into $\ttbar$ gives rise to top quark events
with a hard gluon.


title:
The Mixed Vector Current Correlator <0|T(V^3_\mu V^8_\nu )|0> To Two
  Loops in Chiral Perturbation Theory

abstract:
  The isospin-breaking correlator of the product of flavor octet vector
currents, $V^3_\mu$ and $V^8_\nu$, $\Pi^{38}_{\mu\nu}(q^2)$ is computed to
next-to-next- to-leading (two-loop) order in Chiral Perturbation Theory. Large
corrections to both the magnitude and $q^2$-dependence of the one-loop result
are found, and the reasons for the slow convergence of the chiral series for
the correlator given. The two-loop expression involves a single ${\cal O}(q^6)$
counterterm, present also in the two-loop expressions for
$\Pi^{33}_{\mu\nu}(q^2)$ and $\Pi^{88}_{\mu\nu}(q^2)$, which counterterm
contributes a constant to the scalar correlator $\Pi^{38}(q^2)$. The
feasibility of extracting the value of this counterterm from other sources is
discussed. Analysis of the slope of the correlator with respect to $q^2$ using
QCD sum rules is shown to suggest that, even to two-loop order, the chiral
series for the correlator may not yet be well-converged.


title:
Neutrino Oscillations in the Framework of Three-Generation Mixings with
  Mass Hierarchy

abstract:
  We have analyzed the results of reactor and accelerator neutrino oscillation
experiments in the framework of a general model with mixing of three neutrino
fields and a neutrino mass hierarchy that can accommodate the results of the
solar neutrino experiments. It is shown that $ \nu_\mu \leftrightarrows \nu_e $
oscillations with $ 0.6 \le \Delta m^2 \le 100 \, \mathrm{eV}^2 $ and amplitude
larger than $ 2 \times 10^{-3} $ are not compatible with the existing limits on
neutrino oscillations if the non-diagonal elements of the mixing matrix $
\left| U_{e3} \right| $ and $ \left| U_{\mu3} \right| $ are small. Thus, if the
excess of electron events recently observed in the LSND experiment is due to $
\nu_\mu \leftrightarrows \nu_e $ oscillations, the mixing in the lepton sector
is basically different from the CKM mixing of quarks. If this type of mixing is
realized in nature, the observation of $ \nu_\mu \leftrightarrows \nu_e $
oscillations would not influence $ \nu_\mu \leftrightarrows \nu_\tau $
oscillations that are being searched for in the CHORUS and NOMAD experiments.


title: Quadruple Yukawa Unification in the Minimal Supersymmetric Model

abstract:
  Predictions for m_t, tan beta, m_nu_tau are calculated for quadruple third
family t-b-tau-nu_tau Yukawa unified models in the MSSM. The renormalisation
group equations for the 3 families of the MSSM, including the right handed
neutrino, are presented. For right handed tau neutrino Majorana masses that are
bigger than 10^11 GeV, the tau neutrino mass is consistent with present
cosmological bounds. The m_t, tan beta predictions are approximately equivalent
to those in triple third family Yukawa unified models.


title: Phenomenology of Nuclear Shadowing in Deep-Inelastic Scattering

abstract:
  We investigate shadowing effects in deep-inelastic scattering from nuclei at
small values $x<0.1$ of the Bjorken variable. Unifying aspects of generalized
vector meson dominance and color transparency we first develop a model for
deep-inelastic scattering from free nucleons at small $x$. In application to
nuclear targets we find that the coherent interaction of quark-antiquark
fluctuations with nucleons in a nucleus leads to the observed shadowing at
$x<0.1$. We compare our results with most of the recent data for a large
variety of nuclei and examine in particular the $Q^2$ dependence of the
shadowing effect. While the coherent interaction of low mass vector mesons
causes a major part of the shadowing observed in the $Q^2$ range of current
experiments, the coherent scattering of continuum quark-antiquark pairs is also
important and guarantees a very weak overall $Q^2$ dependence of the effect. We
also discuss shadowing in deuterium and its implications for the quark flavor
structure of nucleons. Finally we comment on shadowing effects in high-energy
photon-nucleus reactions with real photons.


title: On the screening of static electromagnetic fields in hot QED plasmas

abstract:
  We study the screening of static magnetic and electric fields in massless
quantum electrodynamics (QED) and massless scalar electrodynamics (SQED) at
temperature $T$. Various exact relations for the static polarisation tensor are
first reviewed and then verified perturbatively to fifth order (in the
coupling) in QED and fourth order in SQED, using different resummation
techniques. The magnetic and electric screening masses squared, as defined
through the pole of the static propagators, are also calculated to fifth order
in QED and fourth order in SQED, and their gauge-independence and
renormalisation-group invariance is checked. Finally, we provide arguments for
the vanishing of the magnetic mass to all orders in perturbation theory.


title: Physics of Self-Interacting Electroweak Bosons

abstract:
  I will argue why and how it is that precise measurements of the
self-couplings of the weak vector bosons are a vista on the mechanism of
symmetry breaking. Guided by what we have learnt from the present precision
data, it is suggested which of the many so-called anomalous self-couplings
should be given priority in future searches. Expected limits from the upcoming
colliders on the parameters describing non minimal couplings are updated. I
will also point at the complementarity between the LHC and the Next Linear
Collider as concerns $W$ physics and discuss some of the important issues about
radiative corrections and backgrounds that need further studies in order that
one conducts high precision analysis at high energies.


title:
Fermionic Dispersion Relations in the Standard Model at Finite
  Temperature

abstract:
  We compute the one-loop dispersion relations at finite temperature for
quarks, charged leptons and neutrinos in the Minimal Standard Model. The
dispersion relations are calculated in two different plasma situations: for a
vacuum expectation value $\upsilon$ of the Higgs field $\upsilon \neq 0$
(broken electroweak symmetry) and for $\upsilon=0$ (unbroken electroweak
symmetry). The flavour and chiral non-degeneracy of the quasi-particle spectrum
is studied. Numerical results show that the thermal effective masses for
fermions in the broken phase have a smaller value than those in the unbroken
phase. The temperature dependence of the top quark and electron neutrino
thermal effective masses is also presented. Gauge invariance of one-loop
dispersion relations is studied.


title: EMBEDDED DEFECTS AND SYMMETRY BREAKING IN FLIPPED $SU(5)$

abstract:
  We explicitly show the analogy between the symmetry breaking scheme for the
GUT flipped $SU(5)$ with that of the Weinberg-Salam theory of electroweak
interactions. This allows us to construct the embedded defect spectrum of the
theory flipped $SU(5)$. We find that the spectrum consists of twelve
gauge-equivalent unstable Lepto-quark strings, which are analogous to W-strings
in electroweak theory, and another string that is gauge inequivalent to the
Lepto-quark strings, which we call the `V-string'. The V-string is analogous to
the Z-string of electroweak theory, correspondingly admitting a stable
semilocal limit. Using data on the running coupling constants we indicate that
in the non-supersymmetric case V-strings can be stable for part of the
physically-viable parameter space. Cosmological consequences are briefly
discussed.


title: J/Psi Decay Lepton Distribution in Hadronic Collisions

abstract:
  We propose the measurement of the decay angular distribution of leptons from
J/Psi's produced at high transverse momentum balanced by a photon [or gluon] in
hadronic collisions. The polar and azimuthal angular distribution are
calculated in the color singlet model (CSM). It is shown that the general
structure of the decay lepton distribution is controlled by four invariant
structure functions, which are functions of the transverse momentum and the
rapidity of the J/Psi. We found that two of these structure functions [the
longitudinal and transverse interference structure functions] are identical in
the CSM. We present analytical and numerical results in the Collins-Soper and
in the Gottfried-Jackson frame.


title:
QCD Corrections from Top Quark to Relations between Electroweak
  Parameters to Order $\alpha_s^2$

abstract:
  The vacuum polarization functions $\Pi(q^2)$ of charged and neutral gauge
bosons which arise from top and bottom quark loops lead to important shifts in
relations between electroweak parameters which can be measured with
ever-increasing precision. The large mass of the top quark allows approximation
of these functions through the first two terms of an expansion in
$M_Z^2/M_t^2$. The first three terms of the Taylor series of $\Pi(q^2)$ are
evaluated analytically up to order $\as^2$. The first two are required to
derive the approximation, the third can be used to demonstrate the smallness of
the neglected terms. The paper improves earlier results based on the leading
term $\propto G_F M_t^2 \as^2$. Results for the subleading contributions to
$\dr$ and the effective mixing angle $\sineff$ are presented.


title:
Isospin breaking corrections to nucleon form factors in the constituent
  quark model

abstract:
  We examine isospin breaking in the nucleon wave functions due to the $u - d$
quark mass difference and the Coulomb interaction among the quarks, and their
consequences on the nucleon electroweak form factors in a nonrelativistic
constituent quark model. The mechanically induced isospin breaking in the
nucleon wave functions and electroweak form factors are exactly evaluated in
this model. We calculate the electromagnetically induced isospin admixtures by
using first-order perturbation theory, including the lowest-lying resonance
with nucleon quantum numbers but isospin 3/2. We find a small ($\leq 1\%$), but
finite correction to the anomalous magnetic moments of the nucleon stemming
almost entirely from the quark mass difference, while the static nucleon axial
coupling remains uncorrected. Corrections of the same order of magnitude appear
in charge, magnetic, and axial radii of the nucleon. The correction to the
charge radius in this model is primarily isoscalar, and may be of some
significance for the extraction of the strangeness radius from e.g. elastic
forward angle parity violating electron-proton asymmetries, or elastic
${}^4He({\vec e},e')$ experiments.


title: The Supersymmetric Flavor Problem

abstract:
  The supersymmetric $SU(3)\times SU(2)\times U(1)$ theory with minimal
particle content and general soft supersymmetry breaking terms has 110 physical
parameters in its flavor sector: 30 masses, 39 real mixing angles and 41
phases. The absence of an experimental indication for the plethora of new
parameters places severe constraints on theories posessing Planck or GUT-mass
particles and suggests that theories of flavor conflict with naturalness. We
illustrate the problem by studying the processes $\mu \rightarrow e + \gamma$
and $K^0 - \bar{K}^0$ mixing which are very sensitive probes of Planckian
physics: a single Planck mass particle coupled to the electron or the muon with
a Yukawa coupling comparable to the gauge coupling typically leads to a rate
for $\mu \rightarrow e + \gamma$ exceeding the present experimental limits. A
possible solution is that the messengers which transmit supersymmetry breaking
to the ordinary particles are much lighter than $M_{\rm Planck}$.


title: Gauge Symmetries and Vector-Boson Self Interactions

abstract:
  I review why we believe the electromagnetic, strong, and weak interactions
are gauge theories, and what this implies for the self interactions of the
gauge bosons. The modern point of view regarding non-renormalizable effective
field theories is emphasized.


title: Electroweak Precision Data and a Heavy Z'

abstract:
  We consider the physics of an extra $U(1)$ gauge boson $Z'$, which can mix
with $Z$ through intermediate fermion loops. The loop contribution due to the
heavy top quark significantly affects the low-energy observables, and for
$m_{Z'}>m_Z$, one can always adjust the shifts in these observables to be in
the right direction suggested by experiments, when we impose the anomaly
cancellation conditions for $Z'$.


title: Improved Action Method for Analysing Tunneling in Quantum Field Theory

abstract:
  We describe a new method which allows one to evaluate the false vacuum decay
rate for a general potential which may depend on an arbitrary number of scalar
fields.


title: Neutron-antineutron transitions

abstract:
  We confirm our previous limit on the free-space neutron-antineutron
oscillation time t>4.7*10**31 y. The approach is verified by the example of
exactly solvable model. We also discuss the all existing remarks. The approach
with finite time interval includes potential model as an extremely simplified
special case. It is shown that potential model is inapplicable to the problem
in hand because for antineutron-nucleus decay probability it gives W=2. In
particular, as we transparently show, this "decay law" (normalized by factor 2)
is used by Dover, Gal and Richard for refutation of our results.


title:
Chaotic inflation and a radiatively generated intermediate scale in the
  supersymmetric standard model

abstract:
  We consider a phenomenological extension of the minimal supersymmetric
standard model which incorporates chaotic inflation and a radiatively generated
intermediate mass scale. Initially a period of chaotic inflation is driven by a
quartic potential associated with the right-handed electron sneutrino.
Supersymmetry relates the quartic coupling of the inflationary potential to the
electron Majorana neutrino Yukawa coupling, $h_1$. The microwave background
temperature anisotropy determines this coupling to be $h_1\simeq 10^{-7}$,
which is similar in magnitude to the electron Dirac Yukawa coupling. A U$(1)$
Peccei-Quinn (PQ) symmetry is broken by radiative corrections at an
intermediate scale $\simeq 10^{12}$GeV when the universe cools to a temperature
$T\lesssim 10^3$GeV. This leads to an invisible axion, a weak scale $\mu$-term
and an electron Majorana neutrino mass $M_{N_1}\simeq 10^5$GeV. A second
inflationary period can also occur via a flat-direction field. In this case the
universe can be reheated to a temperature $T_{RH}\simeq 10^6$GeV, without
restoring PQ symmetry. Baryogenesis will then occur via out-of-equilibrium
neutrino decay.


title: BARYON-BARYON INTERACTIONS IN LARGE N_C CHIRAL PERTURBATION THEORY

abstract:
  Interactions of two baryons are considered in large $N_C$ chiral perturbation
theory and compared to the interactions derived from the Skyrme model. Special
attention is given to a torus-like configuration known to be present in the
Skyrme model.


title: Fermi-Dirac statistics plus liquid description of quark partons

abstract:
  A previous approach with Fermi-Dirac distributions for fermion partons is
here improved to comply with the expected low $x$ behaviour of structure
functions. We are so able to get a fair description of the unpolarized and
polarized structure functions of the nucleons as well as of neutrino data. We
cannot reach definite conclusions, but confirm our suspicion of a relationship
between the defects in Gottfried and spin sum rules.


title:
Complete O($\alpha$) QED corrections to the process $ep \to eX$ in mixed
  variables

abstract:
  The complete set of ${\cal O}(\alpha)$ QED corrections with soft photon
exponentiation to the process $ep \rightarrow eX$ in mixed variables
($y=y_h,Q^2=Q_l^2$) is calculated in the quark parton model, including the
lepton-quark interference and the quarkonic corrections which were unknown so
far. The interference corrections amount to few percent or less and become
negligible at small $x$. The leading logarithmic terms proportional to
$\ln(Q^2/m_q^2)$ from radiation off quarks are discussed and the
non-logarithmic quarkonic corrections found to be negligible for almost all
experimentally accessible $x$ and $y$.


title:
Probing Higgs Sector CP Violation with Top Quarks at a Photon Linear
  Collider

abstract:
  We investigate for two-Higgs doublet models with intrinsic CP violation in
the scalar potential CP-nonconserving effects in unpolarized $\gamma \gamma
\rightarrow t \bar{t} $ for a range of neutral Higgs boson masses which
includes resonant $\varphi$ production and the subsequent decay of $\varphi
\rightarrow t \bar{t}$. The importance of taking into account, even in the
resonant case, the interference with the nonresonant background is shown.
Further, we propose and calculate three asymmetries which efficiently trace
CP-violating effects in $\gamma \gamma \rightarrow t \bar{t} $ using
semileptonic $t \bar{t}$ decays.


title: Comparison of potential models through HQET

abstract:
  I calculate heavy-light decay constants in a nonrelativistic potential model.
The resulting estimate of heavy quark symmetry breaking conflicts with similar
estimates from lattice QCD. I show that a semirelativistic potential model
eliminates the conflict. Using the results of heavy quark effective theory
allows me to identify and compensate for shortcomings in the model calculations
in addition to isolating the source of the differences in the two models. The
results lead to a rule as to where the nonrelativistic quark model gives
misleading predictions.


title: LHC Analysis of the Strongly Interacting $WW$ System: Gold-Plated Modes

abstract:
  We study the gold-plated purely leptonic signal and background rates at the
LHC for the $ZZ,$ $W^{+}W^-,$ $W^\pm Z$ and $W^\pm W^\pm$ final states
associated with strongly interacting electroweak symmetry breaking. We work at
an energy of $\sqrt s = 14$ TeV, and develop a combination of back-to-back
leptonic, central-jet-vetoing and forwaring cuts that suppresses the
Standard-Model backgrounds. We find that the LHC with an annual luminosity of
100 fb$^{-1}$ will achieve a reasonably good sensitivity to the physics of
strongly interacting electroweak symmetry breaking.


title:
CP Violation and Electroweak Baryogenesis in Extensions of the Standard
  Model

abstract:
  We develop a new and general method to calculate the effects of \cp\
violation from extensions of the standard model on the mechanism of electroweak
baryogenesis. We illustrate its applicability in the framework of two-higgs
doublet models.


title: Non-Leptonic two body decays of Charmed and \Lambda_b Baryons

abstract:
  We calculate the two body Cabibbo allowed non-leptonic decays of charmed
baryons $\Lambda_c$ and $\Xi_c$ which involve transitions of a heavy quark to a
light quark. We use data on the Cabbibo favoured non-leptonic decays $\Lambda_c
\rightarrow \Lambda \pi^{+}$ and $\Lambda_c \rightarrow \Sigma^{+} \pi^{0 }$ to
obtain information on the form factors in the $c \rightarrow s $ transition. We
also calculate the decay $\Lambda_c \rightarrow p \phi$. Using HQET the
information on form factors from the $c \rightarrow s $ transition is used to
model the form factors in $b \rightarrow s $ transition which are then used in
the study of $\Lambda_b \rightarrow J/ \psi \Lambda $ decay.


title:
Semi-Leptonic Decays of \Lambda_c and \Lambda_b Baryons involving Heavy
  to Light Transitions and the determination of V_{ub}

abstract:
  We calculate the semi-leptonic decays of $\Lambda_c$ and $\Lambda_b$ baryons
which involve transitions of a heavy quark to a light quark. In a previous work
we used data on the Cabibbo favoured non-leptonic decays of charmed baryons
$\Lambda_c \rightarrow \Lambda \pi^{+}$ and $\Lambda_c \rightarrow \Sigma^{+}
\pi^{0 }$ to obtain information on the form factors in the $c \rightarrow s $
transition. This form factor informations is used to study the semi-leptonic
decay $\Lambda_c \rightarrow \Lambda l \nu $. Using SU(3) symmetry and HQET it
is shown how a knowledge of form factors in $\Lambda_c \rightarrow \Lambda l
\nu $ can be applied to $\Lambda_b \rightarrow p l \nu $ decay and used to
measure $|V_{ub}/V_{cs}|^{2} $.


title: A New Candidate for the Dark Matter

abstract:
  It is shown that if there are two distinct phase transition temperatures to
the hadronic phase ( as is currently favoured), then QCD demands a condensation
to a weakly interacting massive glueball. This glueball then becomes a natural
candidate for the cosmological dark matter. Note that this does not involve any
exotic extensions beyond the Standard Model of particle physics. In this
revised version at the end of the paper I have added a new section called
ADDENDUM which gives new arguments as to how this very heavy glueball can be
stable and hence be a dark matter candidate.


title: A magic connection between massive and massless diagrams

abstract:
  A useful connection between two-loop massive vacuum integrals and one-loop
off-shell triangle diagrams with massless internal particles is established for
arbitrary values of the space-time dimension n.


title: Two-loop vacuum diagrams and tensor decomposition

abstract:
  General algorithms for tensor reduction of two-loop massive vacuum diagrams
are discussed. Some explicit useful formulae are presented.


title:
THE DECAY $H^0_2\to gg$\ WITHIN THE MINIMAL SUPERSYMMETRIC STANDARD
  MODEL

abstract:
  I present a detailed SUSY QCD calculation of the decay rate of the lightest
Higgs boson $H^0_2$\ into two gluons, where all quarks and scalar quarks are
taken within the relevant loop diagrams. I include the mixing of all the scalar
partners of the left and right handed quarks and show that their contribution
is more than several tens of per cent compared to the quark contribution in the
MSSM for some SUSY parameter space. Furthermore the fermionic contribution is
enhanced by several factors for large $\tan\beta$\ and large Higgs masses. As a
result, the two gluon decay rate of $H_2^0$\ is much larger than the two gluon
decay rate of an equal mass standard model Higgs boson. I further compare the
decay mode of $H^0_2\rightarrow gg$\ to the similar decay modes of
$H^0_2\rightarrow c\overline c$\ and $H^0_2\rightarrow b\overline b$\ including
one loop QCD corrections and show that in some cases $\Gamma(H^0_2\rightarrow
gg)$\ is even higher than $\Gamma(H^0_2\rightarrow c\overline c)$, although
still much smaller than $\Gamma(H^0_2\rightarrow b\overline b)$.


title:
Top Quark Production and Decay at Next-to-leading Order in $e^+e^-$
  Annihilation

abstract:
  We study the effects of QCD corrections to the process $e^+e^-\rightarrow
t\bar t+X\rightarrow b\ell^+\nu \bar b\ell^-\bar \nu+X$ above threshold. We
show how to treat consistently to ${\cal O}(\alpha_s)$ the gluon radiation in
both the production and the decay of the top quarks, while maintaining all
angular correlations in the event. At this order there is an ambiguity in the
event reconstruction whenever a real gluon occurs in the final state. We study
the effects of this ambiguity on the top mass and helicity angle distributions.
For a top mass of 175 GeV and collider energy of 400 GeV the gluon radiation is
emitted predominantly in the decay of the top quarks.


title: Top Quark Mass Enhancement in a Seesaw-Type Quark Mass Matrix

abstract:
  We investigate the implications of a seesaw type mass matrix, i.e.,
$M_f\simeq m_L M_F^{-1} m_R$, for quarks and leptons $f$ under the assumption
that the matrices $m_L$ and $m_R$ are common to all flavors (up-/down- and
quark-/lepton- sectors) and the matrices $M_F$ characterizing the heavy fermion
sectors have the form [(unit matrix) + $b_f$ (a democratic matrix)] where $b_f$
is a flavor parameter. We find that by adjusting the complex parameter $b_f$,
the model can provide that $m_t\gg m_b$ while at the same time keeping $m_u\sim
m_d$ without assuming any parameter with hierarchically different values
between $M_U$ and $M_D$. The model with three adjustable parameters under the
``maximal" top quark mass enhancement can give reasonable values of five quark
mass ratios and four KM matrix parameters.


title: Strong W_L W_L Scattering

abstract:
  I describe theories of a strongly-interacting electroweak symmetry breaking
sector and discuss the expected size of anomalous weak-boson couplings in these
models.


title:
Effects of QCD Resummation on Distributions of Leptons from the Decay of
  Electroweak Vector Bosons

abstract:
  We study the distributions of leptons from the decay of electroweak vector
bosons produced in hadron collisions. The effects of the initial state multiple
soft-gluon emission, using the Collins--Soper resummation formalism, are
included. The resummed results are compared with the next-to-leading-order
results for the distributions of the transverse momentum, rapidity asymmetry,
and azimuthal angle of the decay leptons.


title: A STRANGE MESONIC TRANSITION FORM FACTOR

abstract:
  The strange-quark vector current $\rho$-to-$\pi$ meson transition form factor
is computed at one-loop order using strange meson intermediate states. A
comparison is made with a $\phi$-meson dominance model estimate. We find that
one-loop contributions are comparable in magnitude to those predicted by
$\phi$-meson dominance. It is possible that the one-loop contribution can make
the matrix element as large as those of the electromagnetic current mediating
vector meson radiative decays. However, due to the quadratic dependence of the
one-loop results on the hadronic form factor cut-off mass, a large uncertainty
in the estimate of the loops is unavoidable. These results indicate that
non-nucleonic strange quarks could contribute appreciably in moderate-$|Q^2|$
parity-violating electron-nucleus scattering measurements aimed at probing the
strange-quark content of the nucleon.


title: Flux Tubes in Effective Field Theory

abstract:
  Quark-antiquark bound states are examined in the long-range strong-coupling
limit with the minimal area law of lattice gauge theory assumed as input.
Matrix element relations are established which in the effective theory obtain
dynamical equations equivalent to a formulation of the flux-tube model.


title: Solving the Homogeneous Bethe-Salpeter Equation

abstract:
  We study a method for solving the homogeneous Bethe-Salpeter equation. By
introducing a `fictitious' eigenvalue $\lambda$ the homogeneous Bethe-Salpeter
equation is interpreted as a linear eigenvalue equation, where the bound state
mass is treated as an input parameter. Using the improved ladder approximation
with the constant fermion mass, we extensively study the spectrum of the
fictitious eigenvalue $\lambda$ for the vector bound states and find the
discrete spectrum for vanishing bound state mass. We also evaluate the bound
state masses by tuning appropriate eigenvalues $\lambda$ to be unity, and find
massless vector bound states for specific values of the constant fermion
masses.


title: A Global Fit of LEP/SLC Data with Light Superpartners

abstract:
  We find that re-analyzing the LEP/SLC data with light superpartners and low
$\alpha_s(\mz^2)\simeq 0.112$ yields a better fit to the data than the Standard
Model, giving a satisfactory description of the $R_b$ measurement, and a better
fit to $A_{LR}$. A large body of low energy ($q^2 \ll \mz^2$) data and analyses
provide compelling evidence for $\alpha_s(\mz^2)\simeq 0.112$. Global fits to
LEP/SLC data in the Standard Model, however, converge on a value of
$\alpha_s(\mz^2)\simeq 0.126$. Recently it has become increasingly clear that
these should be viewed as incompatible rather than values that can be averaged.
We investigate the possibility that new physics is causing the LEP high value.
To this end we have conducted a global analysis of LEP/SLC data in the Standard
Model and also in the Minimal Supersymmetric Standard Model. Several
predictions could confirm (or rule out) the results of this paper: light
chargino and stop, top decays into stop and neutralino, large $R_b$, large
$A_{LR}$, and a higher $M_W$. We briefly discuss the implications of low
$\alpha_s$ for more fundamental high-scale supersymmetric theories.


title: SOLVING THE BETHE--SALPETER EQUATION IN MINKOWSKI SPACE: SCALAR THEORIES

abstract:
  The Bethe-Salpeter (BS) equation for scalar-scalar bound states in scalar
theories without derivative coupling is formulated and solved in Minkowski
space. This is achieved using the perturbation theory integral representation
(PTIR), which allows these amplitudes to be expressed as integrals over weight
functions and known singularity structures and hence allows us to convert the
BS equation into an integral equation involving weight functions. We obtain
numerical solutions using this formalism for a number of scattering kernels to
illustrate the generality of the approach. It applies even when the na\"{\i}ve
Wick rotation is invalid. As a check we verify, for example, that this method
applied to the special case of the massive ladder exchange kernel reproduces
the same results as are obtained by Wick rotation.


title:
An exact analytic description of neutrino oscillations in matter with
  exponentially varying density for arbitrary number of neutrino species

abstract:
  Exact analytical expressions in terms of generalized confluent hypergeometric
functions for the transition amplitudes of neutrino oscillations in presence of
matter are computed for an arbitrary number of species. The density of matter
is assumed to be exponentially decaying. The results can be used for the
description of matter-induced neutrino oscillations in the Sun which can take
place when the solar neutrinos propagate radially from the interior to the
surface. Expressions are particularly simple in the limit of infinite
propagation time as is suitable for the case of detection at Earth. PACS:
14.60.Pq, 02.30.Gp, 02.30.Hq


title: Neutrino conversions in hot plasma

abstract:
  We discuss the excitation of sterile neutrinos in the early universe using
general quantum kinetic equations, which also incorporate a possible primordial
magnetic field $B$. We find a new contribution to the excitation propability,
which has its origin in the shrinkage of the spin vector. In the absence of $B$
nucleosynthesis implies the constraint $\mid \Delta m^2\mid\sin^22\theta_0\lsim
1.6\times 10^{-6}~{\rm eV}^2$ which is more restrictive than previous
estimates. We also present examples of possible stringent limits for $B\ne 0$.


title: The Higgs Boson Lineshape and Perturbative Unitarity

abstract:
  We discuss the lineshape of a heavy Higgs boson, and the behaviour well above
resonance. Previous studies concluded that the energy-dependent Higgs width
should be used in the resonance region, but must not be used well away from it.
We derive the full result and show that it smoothly extrapolates these limits.
It is extremely simple, and would be straightforward to implement in existing
calculations.


title: Top Quark Production in Extended Bess Model

abstract:
  We study top production at Tevatron collider in the extended BESS model,
which is an effective lagrangian parametrization of a dynamical symmetry
breaking of the electroweak symmetry. The existence of a colored octet of gauge
vector bosons can increase top production at a rate still consistent with
recent experimental data and lead to distorsions in the transverse momentum
spectrum of the top.


title: Accidental $\xi$-scaling as a Signature of Nuclear Effects at $x>1$

abstract:
  We propose an interpretation of the $\xi$-scaling behavior of nuclear
structure functions observed at Bjorken $x>1$ and $Q^2 \lesssim 4 \, {\rm
(GeV/c)^2}$. We show that at $\xi \gtrsim 1$, $\xi$-scaling might arise
accidentally because of the approximate cancellation of two different
$Q^2$-dependent effects, namely Final State Interactions and the effects
implicit in the choice of the scaling variable $\xi$. We provide a new
convolution formula for the nuclear structure function in terms of $\xi$ and
make predictions for the kinematical regions where Final State Interactions are
expected to be small and the suggested balancing of scaling violations is
expected to break down. Our analysis is aimed at the final goal of clarifying
the range of applicability of local duality ideas in nuclei.


title: Hidden Matter Condensation Effects on Supersymmetry Breaking

abstract:
  We investigate the effects of hidden matter condensation on supersymmetry
breaking in supergravity models derived from free fermionic strings. We find
that the minimum of the effective potential in the modulus direction depends
strongly on only one parameter which is fixed by the hidden sector. For
nonpositive values of the parameter the potential is unstable which constrains
realistic models severely. For positive and decreasing values which correspond
to more and/or lighter hidden matter, $T_R$ increases whereas $T_I$ is periodic
and depends on the parameter very weakly. Supersymmetry can be broken in the
matter direction with a stable vacuum only if the fields which give mass to the
hidden matter are light and have modulus independent Kahler potentials. Then,
for a wide range of model parameters, supersymmetry is mainly broken by hidden
matter condensation in the matter direction rather than by hidden gaugino
condensation in the modulus direction.


title: Bound $q^2\bar q^2$ states in a constituent quark model

abstract:
  We consider the existence of bound systems consisting of two quarks and two
antiquarks ($q^2\bar q^2$) within the framework of a constituent quark model.
The underlying quark dynamics is described by a linear confinement potential
and an effective $q^2\bar q^2$ interaction which has its origin in instanton
effects of QCD. We calculate the spectra and examine the internal structure of
the states found.


title: Studying medium effects with the optimized $\bdelta$ expansion

abstract:
  The possibility of using the optimized $\delta$ expansion for studying medium
effects on hadronic properties in quark or nuclear matter is investigated. The
$\delta$ expansion is employed to study density effects with two commonly used
models in hadron and nuclear physics, the Nambu--Jona-Lasinio model for the
dynamical chiral symmetry breaking and the Walecka model for the equation of
state of nuclear matter. The results obtained with the $\delta$ expansion are
compared to those obtained with the traditional Hartree-Fock approximation.
Perspectives for using the $\delta$ expansion in other field theoretic models
in hadron and nuclear physics are discussed.


title: Spectra of baryons containing two heavy quarks

abstract:
  The spectra of baryons containing two heavy quarks test the form of the $QQ$
potential through the spin-averaged masses and hyperfine splittings. The mass
splittings in these spectra are calculated in a nonrelativistic potential model
and the effects of varying the potential studied. The simple description in
terms of light quark and pointlike diquark is not yet valid for realistic heavy
quark masses.


title:
Radiowave Method of High Energy Neutrino Detection: calculation of the
  expected event rate

abstract:
  The sensitivity of an ice radiowave detector to the anticipated high energy
neutrino fluxes is calculated on the basis of a detailed threshold analysis and
computation of the shower production rate. We show that diffuse neutrinos from
Active Galactic Nuclei could be detectable in a radio detector of 1 sq.km area
established in Central Antarctica.


title: EVIDENCE FOR A SCALAR GLUEBALL

abstract:
  We show that the newly discovered scalar meson $f_0(1500)$ at LEAR has
properties compatible with the lightest scalar glueball predicted by lattice
QCD and incompatible with a $\qqbar$ state. We suggest that decays of glueballs
are into pairs of glueballs (including $\eta, \eta'$ or $(\pi\pi)_S$) or by
mixing with nearby $Q\bar{Q}$ states. The partial widths of $f_0(1500)$ are in
accord with this hypothesis, tests of which include characteristic radiative
decays to $\gamma\phi,\gamma\omega, \gamma\rho$ and the prediction of a further
scalar state, $f_0'(1500 - 1800)$ which couples strongly to $K\bar{K}$,
$\eta\eta$ and $\eta\eta'$.


title: Reheating the Post Inflationary Universe

abstract:
  We consider the non-equilibrium evolution of the inflaton field coupled to
both lighter scalars and fermions. The dissipational dynamics of this field is
studied and found to be quite different than that believed in inflationary
models. In particular, the damping time scale for the expectation value of the
zero momentum mode of the inflaton can be much shorter than that given by the
single particle decay rate when the inflaton amplitudes are large, as in
chaotic inflation scenarios. We find that the reheating temperature may depart
considerably from the usual estimates.


title:
RENORMALISATION GROUP AIDED FINITE TEMPERATURE REDUCTION OF QUANTUM
  FIELD THEORIES

abstract:
  Dimensional reduction of finite temperature quantum field theories can be
improved with help of continous renormalisation group steps. The method is
applied to the integration of the lowest non-static ($n=\pm 1$) modes of the
finite temperature $\Phi^4$-theory. A second, physically important application
is the integration of the Debye-screened ${\bf A_0}(x)$ static scalar potential
in the gauged SU(2) Higgs model.


title: LONG DISTANCE EFFECTS AND CP VIOLATION in $B^{\pm}\to\rho^{\pm}\gamma$

abstract:
  We demonstrate that the long distance contribution to $B^{\pm} \to \rho^{\pm}
\gamma$ may have a large effect on the decay rate and through it on the CP
violating partial rate asymmetry. The change in the asymmetry can be between a
factor of 0.4 and 1.4 with respect to the effect of the short distance
contribution alone, depending on the values of the CKM parameters $\rho$ and
$\eta$ .


title: WEAK DIPOLE MOMENTS AT ${\bf e^+e^-}$ COLLIDERS

abstract:
  The weak dipole moments of leptons and quarks, \ie those related to their
$Z$--coupling, are reviewed. Standard Model predictions and experimental
results may result in a stringent test for both their pointlike structure and
also for the Standard Model. Special attention is devoted to the anomalous
weak--magnetic dipole moment and to the $CP$--violating weak--electric dipole
moment.


title: All-Orders Renormalon Resummations for some QCD Observables

abstract:
  Exact large-$N_{f}$ results for the QCD Adler $D$-function and Deep Inelastic
Scattering sum rules are used to resum to all orders the portion of QCD
perturbative coefficients containing the highest power of
$b$=$\frac{1}{6}(11N$--$2N_{f})$, for SU($N$) QCD with $N_{f}$ quark flavours.
These terms correspond to renormalon singularities in the Borel plane and are
expected asymptotically to dominate the coefficients to all orders in the
$1/N_{f}$ expansion. Remarkably, we note that this is already apparent in
comparisons with the exact next-to-leading order (NLO) and next-to-NLO (NNLO)
perturbative coefficients. The ultra-violet ($UV$) and infra-red ($IR$)
renormalon singularities in the Borel transform are isolated and the Borel sum
(principal value regulated for $IR$) performed. Resummed results are also
obtained for the Minkowski quantities related to the $D$-function, the
$e^{+}e^{-}$ $R$-ratio and the analogous $\tau$-lepton decay ratio, $R_{\tau}$.
The renormalization scheme dependence of these partial resummations is
discussed and they are compared with the results from other groups [1--3] and
with exact fixed order perturbation theory at NNLO. Prospects for improving the
resummation by including more exact details of the Borel transform are
considered.


title: Low-Energy Theorems in Higgs Physics

abstract:
  We present low-energy theorems for the calculation of loop amplitudes with
external scalar or pseudoscalar Higgs bosons which are light compared to the
loop particles. Starting from existing lowest-order versions of these theorems,
we show how their applicability may be extended to the two--loop level. To
illustrate the usefulness of these theorems, we discuss a number of
applications to Higgs production and decay at and beyond the one--loop order.


title:
On the Possible Violation of Sum Rules for Higher-Twist Parton
  Distributions

abstract:
  Precise measurements of polarized electro-production and Drell-Yan in the
deep inelastic limit will soon provide first information on the higher twist
parton distributions $g_T(x)$ and $h_L(x)$. Sum rules for higher-twist
structure functions are only valid provided the corresponding Compton
amplitudes satisfy un-subtracted dispersion relations. Subtracted dispersion
relations have to be used when the (real part of the) forward scattering
amplitudes does not fall off rapidly enough for $\nu \rightarrow \infty$ (fixed
$Q^2$). Formally, such subtractions lead to $\delta$-functions at the origin in
the parton distributions, which are not accessible to experiment, and the
integral over the data fails to satisfy the sum rule. The $\delta$-functions in
the parton distributions can be identified with the zero-modes that appear in
light-front quantization. An explicit {\it infinite momentum boost} identifies
these soft quark modes with low momentum contributions to the self-energy.


title: TOWARDS A UNIFIED ORIGIN OF FORCES, FAMILIES, AND MASS SCALES

abstract:
  A case is made for an alternative approach to unification that is based on a
{\it purely gauge origin of the fundamental forces}, and is thus devoid of the
Higgs-sector altogether. This approach seems to call for the ideas of local
supersymmetry and preons. The advantage of this marriage of the ideas of local
supersymmetry and preons, subject to two broad dynamical assumptions which are
specified, are noted. These include true economy and viability as well as an
understanding of the origins of (a) family-replication, (b) inter-family
mass-hierarchy, and (c) diverse mass-scales which span from $M_{Planck}$ to
$m_W \sim m_t$ to $m_e$ to $m_\nu$. In short, the approach seems capable of
providing {\it a unified origin of the forces, the families and the
mass-scales}. In the process, the preonic approach provides the scope for
synthesizing a rich variety of phenomena all of which could arise dynamically
through one and the same tool -- the SUSY metacolor force coupled with gravity
-- at the scale of $10^{11}GeV$. The phenomena include: (i) spontaneous
violations of parity, CP, B-L and Peccei-Quinn symmetry, (ii) origin of heavy
Majorana mass for $\nu_R$, (iii) SUSY breaking, (iv) origins of even $m_W,~m_q$
and $m_\ell$, as well as, (v) inflation and lepto/baryo-genesis. Some
intriguing experimental consequences of the new approach which could show at
LEPI, LEPII and Tevatron and a {\it crucial prediction} which can be probed at
the LHC and NLC are presented.


title: Virtual Effects of Physics Beyond the Standard Model

abstract:
  We examine the indirect effects of new physics on a variety of processes in
the $B$ system, such as the $Z\to b\bar b$ vertex, the decays $B\to X_s \gamma$
and $B\to X_s\ell^+\ell^-$, and CP violation. {Presented at the 4th
International Conference on Physics Beyond the Standard Model, Lake Tahoe, CA,
December 13-18, 1994}


title:
THREE TYPES OF FERMION MIXING AND POSSIBLE MANIFESTATIONS OF A
  PATI--SALAM LEPTOQUARK IN THE LOW--ENERGY PROCESSES

abstract:
  I report the recent studies\cite{1,2} on the low--energy manifestations of a
minimal extension of the Standard Model based on the quark-lepton symmetry
$SU(4)_V \otimes SU(2)_L \otimes G_R$ of the Pati-Salam type. Given this
symmetry the third type of mixing in the interactions ot the $SU(4)_V$
leptoquarks with quarks and leptons is shown to be required. An additional
arbitrariness of the mixing parameters could allow, in principle, to decrease
noticeably the lower bound on the vector leptoquark mass originated from the
low-energy rare processes. The decays $\mu \rightarrow e \gamma$, $\mu
\rightarrow e \gamma \gamma$, and $\mu \rightarrow e e \bar e$ via the vector
leptoquark are analysed and the specific hierarchy of the decay probabilities
$\Gamma(\mu \rightarrow e e \bar e) \gg \Gamma(\mu \rightarrow e \gamma \gamma)
\gg \Gamma(\mu \rightarrow e \gamma)$ is shown to exist. The upper limits on
the branching ratios at a level of $10^{-18}$ for the $\mu \rightarrow e \gamma
\gamma$ decay and at a level of $10^{-15}$ for the $\mu \rightarrow e e \bar e$
decay are established.


title:
Charm Production in Deep-Inelastic $e\gamma$ Scattering To
  Next-To-Leading Order in QCD

abstract:
  We discuss the calculation of $F_2^{\gamma}({\rm charm})$ to next-to-leading
order (NLO) in QCD, including contributions from both hadronlike and pointlike
photons. We show that the former dominates strongly below $x\simeq 0.01$, and
the latter above this value. This fact makes $F_2^{\gamma}({\rm charm})$ for $x
\geq 0.01$ calculable, whereas for $x \leq 0.01$ it serves to constrain the
small-$x$ gluon density in the photon. Both ranges in $x$ are accessible at
LEP2. Theoretical uncertainties are well under control. We present rates for
single-tag events for the process for $e^+e^- \rightarrow e^+e^- c X$ for LEP2.
Although these event rates are small, we believe a measurement of
$F_2^{\gamma}({\rm charm})$ is feasible.


title: QUANTUM CHROMODYNAMICS

abstract:
  These lectures provide an overview of Quantum Chromodynamics (QCD), the
$SU(3)_C$ gauge theory of the strong interactions. After briefly reviewing the
empirical considerations which lead to the introduction of {\it colour}, the
QCD Lagrangian is discussed. The running of the strong coupling and the
associated property of {\it Asymptotic Freedom} are analyzed. Some selected
experimental tests and the present knowledge of $\alpha_s$ are summarized. A
short description of the QCD flavour symmetries and the {\it dynamical breaking
of chiral symmetry} is also given.


title: Light-Front Heavy Quark Effective Theory and Heavy Meson Bound States

abstract:
  The heavy quark effective theory is developed on the light-front. Based on
this effective theory, a light-front heavy meson bound state with definite spin
and parity is constructed. Within the effective theory, the Isgur-Wise function
is derived in terms of the asymptotic light-front bound state amplitudes in the
limit $m_Q\rightarrow\infty$; the result is a general expression for arbitrary
recoil velocities. With the asymptotic form of the BSW amplitudes, the
Isgur-Wise function is given by $\xi(v\cdot v')=1/v\cdot v'$. The slope at the
zero-recoil point is $\rho^2=-\xi'(1)=1$, in excellent agreement with the
recent CLEO result of $\rho^2=1.01\pm0.15\pm0.09$.


title: Neutral Higgs CP Violation at $\mu^+\mu^-$ colliders

abstract:
  CP violating asymmetries in both the production and the decays of $s$-channel
neutral Higgs bosons at $\mu^+\mu^-$ colliders can be large. If the CP
violation occurs in the muon-Higgs coupling, one observes a production
asymmetry with transversely polarized $\mu^+\mu^-$ beams. Likewise if the CP
violation occurs in the top-Higgs or $\tau$-Higgs coupling, one observes an
azimuthal decay asymmetry in $\mu^+\mu-\to t\bar t$ (or $\tau^+\tau^-$). CP
studies at such colliders allow a uniquely clean way of deducing the underlying
CP phases; in turn these parameters would significantly improve our
understanding of baryogenesis.


title:
Isospin Coherence and Final-State Scattering of Disoriented Chiral
  Condensate

abstract:
  We examine the validity of the notion of the coherent state for pions and the
quantum scattering effect in the final state of pion emission. When the number
of particles is large, the effect caused by the small but finite mass
difference between the neutral and charged pions can add up substantially in
the quantum evolution of an initially coherent state. As a result, the states
with quite different numbers of neutral or charged pions are essentially
incoherent. The importance of the quantum scattering in the final-state isospin
charge distribution of a disoriented chiral condensate (DCC) is investigated.
We find that the scattering effect significantly reduces the spectacular
Centauro and anti-Centauro events. The deformation of a charge distribution
$dP/df$ predicted by the classical field theory is significant only for a DCC
with the size of 10 fm or more.


title: U(3)_{L}\times U(3)_{R} Chiral Theory of Mesons

abstract:
  The chiral theory of mesons of two flavors have been extended to mesons
containing strange flavor. Two new mass relations between vector and
axial-vector mesons have been obtained. In chiral limit, the physical processes
of normal parity and abnormal parity have been studied. Due to the universality
of the coupling of this theory many interesting results have been obtained. In
chiral limit theoretical results are in reasonable agreement with data.


title:
Feynman Diagram Calculations - From finite Integral Representations to
  knotted Infinities

abstract:
  Work is reported on finite integral representations for 2-loop massive 2-, 3-
and 4-point functions, using orthogonal and parallel space variables. It is
shown that this can be utilized to cover particles with arbitrary spin (tensor
integrals), and that UV divergences can be absorbed in an algebraic manner.
This includes a classification of UV divergences by means of the topology of
the graph, interpreted in terms of knots.


title: Ground State for the Quark Mass Hierarchy and Mixings

abstract:
  A multiflavor model for dynamical chiral breaking reveals a solution highly
suitable for stimulation of flavor mass hierarchy and mixings. The mechanism
triggering the both phenomena simultaneously suppresses flavor changings. Thus,
the main features of the observed quark system may spontaneously appear as
inherent properties of a specific ground state.


title: Uncertainties in the Determination of $|V_{cb}|$

abstract:
  I discuss the theoretical uncertainties in the extraction of $|\,V_{cb}|$
from semilep\-to\-nic decays of $B$ mesons, taking into account the most recent
theoretical developments. The main sources of uncertainty are identified both
for the exclusive decay mode $B\to D^*\ell\,\bar\nu$ and for the inclusive
channel $B\to X\,\ell\,\bar\nu$. From an analysis of the available experimental
data, I obtain $|\,V_{cb}|_{\rm excl} = 0.041\pm 0.003_{\rm exp}\pm 0.002_{\rm
th}$ from the exclusive mode, and $|\,V_{cb}|_{\rm incl} = 0.040\pm 0.001_{\rm
exp}\pm 0.005_{\rm th}$ from the inclusive mode. I also give a prediction for
the slope of the form factor ${\cal{F}}(w)$ at zero recoil, which is
$\widehat\varrho^2=0.8\pm 0.3$.


title:
Helicity-Flip Bremsstrahlung and the Measurement of CP-Violating Form
  Factors in Polarized $e^+e^-$ Collisions

abstract:
  Certain momentum correlations in the production and subsequent decay of heavy
fermion pairs in $e^+e^-$ collisions have increased sensitivity to CP-violating
electric and ``weak" dipole form factors of the fermion in the presence of
longitudinal polarization of the $e^+e^-$ beams. However, unless the
polarizations of $e^+$ and $e^-$ are equal and opposite, collinear
initial-state radiation accompanied by helicity flip results in a CP-invariant
contribution to these and acts as a background, and must be calculated and
subtracted in order to isolate the CP-violating contribution due to the dipole
form factor.We calculate this background contribution to such correlations, to
order $\alpha$, in $e^+e^-\rightarrow \tau^+\tau^-$ and $e^+e^-\rightarrow
t\bar{t}$. For the anticitipated luminosities at $\tau$-charm factories and
SLC, for the $\tau$, and at a future linear collider with centre-of-mass energy
of 500 GeV for the top, these backgrounds are smaller than the statistical
background and may be safely neglected.


title: Challenges For Non-Minimal Higgs Searches at Future Colliders

abstract:
  In models with a non-minimal Higgs sector, the lightest scalar state may be a
neutral CP-even Higgs boson, whose properties are nearly identical to those of
the minimal Higgs boson of the Standard Model. In such a scenario, the other
Higgs scalars are significantly heavier than $m_Z$; their effects rapidly
decouple from the low-energy theory. The decoupling limit of the most general
CP-conserving two-Higgs doublet model is formulated. Detection of evidence for
a non-minimal Higgs sector in the decoupling limit presents a formidable
challenge for Higgs searches at future colliders.


title:
Baryogenesis from Domain Walls in the Next-to-Minimal Supersymmetric
  Standard Model

abstract:
  We consider the production of baryon number from collapsing domain walls, and
in particular examine the magnitude of CP violation which is required in such
schemes. Taking the conventional solution to the domain wall problem in the
Next-to-Minimal Supersymmetric Standard Model as an example, we show that the
observed baryon assymmetry of the universe may have been generated, even if the
initial {\em explicit} CP violation in the Lagrangian were so small ({\em i.e.}
gravitational) that it could never be experimentally detected. This is possible
by having the {\em explicit} CP violation affect the way in which the walls
collapse, rather than be responsible for the generation of baryon number
directly. Net baryon number is created at the domain walls by the spontaneous
breaking of CP.


title: Universality and the sparticle spectrum

abstract:
  We calculate the particle spectrum of the SSM which follows from the
assumption that the commonly assumed universal form of the soft supersymmetry
--breaking terms is invariant under renormalisation. It is argued that this
``strong'' universality might be approached as an infra--red fixed point for
the unified theory above the unification scale.


title: AN OPERATOR ANALYSIS OF A SUPERSYMMETRIC EFFECTIVE THEORY

abstract:
  An analysis of a $SU(2)_L \times SU(2)_R$ invariant, supersymmetric effective
theory is given. The resulting leading and next to leading independent
invariants are stated in terms of the underlying Killing vectors and K\"ahler
potential. The appendices are devoted to the relationship between this
geometrical point of view and the standard unitary matrix formulation.


title: Destabilizing Divergences in Supergravity Theories at Two Loops

abstract:
  We examine the stability of the mass hierarchy in hidden-sector supergravity
theories. We show that a quadratically divergent tadpole can appear at two
loops, even in minimal supergravity theories, provided the theory has a gauge-
and global-symmetry singlet with renormalizable couplings to the visible
fields. This tadpole can destabilize the hierarchy. We also find a
quadratically divergent two-loop contribution to the field-dependent vacuum
energy. This result casts doubt on the efficacy of the "LHC mechanism" for
controlling quadratic divergences. We carry out the two-loop calculation in a
manifestly supersymmetric formalism, and explain how to apply the formalism in
the presence of supersymmetry breaking to derive radiative corrections to the
supersymmetric and soft supersymmetry-breaking operators. Our approach greatly
simplifies the calculation and guarantees consistency of our results with the
underlying supergravity framework.


title:
Possible Signals of Constrained Minimal Supersymmetry at a High
  Luminosity Fermilab Tevatron Collider

abstract:
  We study the most promising signals of Constrained Minimal Supersymmetry
detectable at a luminosity upgraded 2 TeV Fermilab Tevatron collider. Using a
full event-level Monte Carlo based on Pythia/Jetset, we simulate the trilepton
signal examining in detail the effect of constraints on the parameter space. We
also simulate the monolepton and dilepton signals, the missing E_T + jets
signal, and the signals of stop production in supersymmetry all with full
Standard Model backgrounds with realistic detector cuts. We find that large
fractions of parameter space can be probed (or eliminated if no signal is
found), but mass limits on charginos and neutralinos are not possible based
solely on the trilepton signal. Detection efficiencies depend strongly on
supersymmetry parameters beyond simply the neutralino and chargino masses;
analyses (experimental or theoretical) that do not include this will draw
misleading conclusions. Finally, we comment on how searches at LEP II will
complement searches at Fermilab.


title: Searching for New Physics with Charm

abstract:
  We consider the prospect of using the charm system as a laboratory for
probing new physics. The theoretical expectations for rare charm meson decays,
$D^0-bar D^0$ mixing, and charm quark asymmetries in $Z$ decays are examined in
the Standard Model. The effects of new physics from several classes of
non-standard dynamical models are summarized for these phenomena. {Presented at
{\it Lafex International School on High Energy Physics (LISHEP95)}, Rio de
Janeiro, Brazil, February 6-22, 1995}


title: Probing New Physics in B Penguins

abstract:
  Constraints placed on physics beyond the Standard Model from the recent CLEO
observation of the inclusive decay $B\to X_s\gamma$ are summarized. Further
searches for new physics using the process $B\to X_s\ell^+\ell^-$ are
discussed. {Presented at the {\it International Workshop on B Physics: Physics
Beyond the Standard Model at the B Factory}, Nagoya, Japan, October 26-28,
1994}


title: Supersymmetry without R-Parity and without Lepton Number

abstract:
  We investigate Supersymmetric models where neither R parity nor lepton number
is imposed. Neutrino masses can be kept highly suppressed compared to the
electroweak scale if the $\mu$-terms in the superpotential are aligned with the
SUSY-breaking bilinear $B$-terms. This situation arises naturally in the
framework of horizontal symmetries. The same symmetries suppress the trilinear
R parity violating terms in the superpotential to an acceptable level.


title: Indications on the Higgs-Boson Mass from the LEP Data

abstract:
  We update our previous analysis on the Higgs mass $m_h$ and the QCD coupling
$\alpha_s(=\alpha_s(M_z))$ by using the LEP data after the 1995 Winter
Conferences. For $m_t=180$ GeV we find evidence for a rather large value of the
Higgs mass in the range 500-1000 GeV, in agreement with the indications from
the W mass.


title:
Production of a chaotic squeezed state from a ``pion liquid" and
  overbunching of identical pion correlations

abstract:
  It is shown that a one to one correspondence between quantum fields in two
different "phases" as might be realized for pions produced from a "hadron
liquid" leads to squeezed states. The single and double inclusive cross
sections for at chaotic superposition of such states are calculated. The
correlation of identical pions is overbunched in comparison with canonical
Bose-Einstein correlations.


title: Hadronic Light-by-Light Contribution to the Muon $g-2$

abstract:
  Mistake in FORTRAN program corrected. The numerical results and conclusions
are changed significantly: We present a calculation of the hadronic
light-by-light contributions to the muon $g-2$ in the $1/N_c$ expansion. We
have used an Extended NJL model and introduced an explicit cut-off for the high
energy region. We have then critically studied the relative size of the high
energy contributions. Although we find them large we can give a conservative
estimate of the light-by-light contribution to $a_\mu$ which is $-(11\pm5)
\cdot 10^{-10}$. This is between two and three sigmas the expected experimental
uncertainty at the forthcoming BNL experiment.


title: Quartic Gauge Boson Couplings

abstract:
  Quartic vertices provide a window into one of the most important problems in
particle physics; the understanding of electroweak symmetry breaking. I survey
the various processes that have been proposed to study quartic gauge boson
couplings at future $e^+e^-$, $e\gamma$, $\gamma\gamma$, $e^-e^-$, and $pp$
colliders. For the lowest dimension operators that do not include photons, it
appears that the LHC will provide the most constraining measurements. However,
precision measurements at high energy $e^+e^-$ colliders involving $W^+W^-$
rescattering are also quite sensitive to the effects of a strongly interacting
weak interaction. For quartic couplings involving photons, $\gamma\gamma$
collisions appear to be the best place to measure these couplings. Measurements
using gauge boson production in $e\gamma$ collisions are almost as precise as
the $\gamma\gamma$ processes with $e^+e^-\to VVV$ about an order or magnitude
less sensitive.


title: REMOVING THE COSMOLOGICAL BOUND ON THE AXION SCALE

abstract:
  The current cosmological bound on the invisible axion scale may be avoided in
the class of theories in which the gauge coupling constant is determined
through the expectation value of some scalar field (e.g. moduli in supergravity
and string theories). This leads to the cosmological scenario different from
that of the standard invisible axion, since the initial values of the fields
are usually far away from their true minima, allowing for the color group
becoming strong in the very early universe and fixing the axion field to its
minimum. The effect disappears as soon as scalar field adjusts to its present
value, but the above is enough to ensure that the deviation of the axion
expectation value from the minimum is negligible at the moment of the QCD phase
transition and thus to eliminate the troublesome coherent oscillations. This
may imply that the standard axion window does not necessarily hold in generic
supergravity theories. The above observation may open a natural possibility for
the existence of the axion resulting from the GUT or R-symmetry breaking.


title: INTRODUCTION TO THE POMERON STRUCTURE FUNCTION

abstract:
  In many ways the pomeron is like the photon, but there are important
differences. Factorisation allows us to define a pomeron structure function,
even though the pomeron is not a particle. Although we have a model for the
light-quark content of the pomeron, which led to the prediction that a
surprisingly large fraction of events at HERA would have an extremely-fast
final-state proton, its charm and gluon content will have to be got from
experiment. Because the pomeron is not a particle, we cannot derive a momentum
sum rule.


title:
The Measurement of Tri-Linear Gauge Boson Couplings at $e^+e^-$
  Colliders

abstract:
  We describe a detailed study of the process $e^+e^- \to \ell\nu_\ell q
\bar{q}$ and the measurement of tri-linear gauge boson couplings (TGV's) at
LEP200 and at a 500~GeV and 1~TeV NLC. We included all tree level Feynman
diagrams contributing to the four-fermion final states including gauge boson
widths and non-resonance contributions. We employed a maximum likelihood
analysis of a five dimensional differential cross section of angular
distributions. This approach appears to offer an optimal strategy for
measurement of TGV's. LEP200 will improve existing measurements of TGV's but
not enough to see loop contributions of new physics. Measurements at the NLC
will be roughly 2 orders of magnitude more precise which would probe the
effects of new physics at the loop level.


title: Observing the technieta at a photon linear collider

abstract:
  If electroweak symmetry is spontaneously broken by technicolor, there will be
technimesons analogous to the mesons of the ordinary strong interactions. One
of the lightest technimesons is the technieta $\eta'_T$ (the analogue of
the~$\eta'$). In this work we consider the possibility of observing it at a
linear $e^+e^-$ collider operating in the $\gamma\gamma$ mode. Detecting the
process $\gamma\gamma\rightarrow\eta'_T$ allows for the measurement of the
$\eta'_T\gamma\gamma$ anomalous coupling which is in principle sensitive to the
underlying technifermion substructure.


title: To VMD, or not to VMD, in the quark-gluon plasma

abstract:
  I review results on the shift of the $\rho$ meson mass at nonzero temperature
in a gauged linear sigma model, under the assumption of strict vector meson
dominance. (Based upon a talk presented at the International Workshop on
"Chiral Dynamics in Hadrons and Nuclei", Seoul, Korea, Feb., 1995).


title: A Proposed Scale-Dependent Cosmology for the Inhomogeneous Cosmology

abstract:
  We propose a scale-dependent cosmology in which the Robertson--Walker metric
and the Einstein equation are modified in such a way that $\Omega_0$, $H_0$ and
the age of the Universe all become scale-dependent. Its implications on the
observational cosmology and possible modifications of the standard Friedmann
cosmology are discussed. For example, the age of the Universe in this model is
longer than that of the standard model.


title: Light Front Quantization

abstract:
  An introductory overview on Light-Front quantization, with some emphasis on
recent achievements, is given. Light-Front quantization is the most promising
and physical tool to study deep inelastic scattering on the basis of quark
gluon degrees of freedom. The simplified vacuum structure (nontrivial vacuum
effects can only appear in zero-mode degrees of freedom) and the physical basis
allows for a description of hadrons that stays close to intuition. Recent
progress has ben made in understanding the connection between effective LF
Hamiltonians and nontrivial vacuum condesates. Discrete Light-Cone
Quantization, the transverse lattice and Light-Front Tamm-Dancoff (in
combination with renormalization group techniques) are the main tools for
exploring LF-Hamiltonians nonperturbatively.


title: Quark Mass Hierarchy and CP Violation in Low Energy Supersymmetry

abstract:
  A pattern of quark mass hierarchy and CP violation within the framework of
low energy supersymmetry is described. By assuming some discrete symmetry among
the three families, the quarks of the third family obtain masses at tree level.
The second family obtains masses radiatively at one-loop level due to the soft
breaking of the family symmetry. At this level, the first family remains
massless by some degeneracy conditions of the squarks. As a result of R-parity
violation, the sneutrino vacuum expectation values are nonvanishing. CP
violation occurs through the superweak sneutrino exchange. This picture is
consistent with the experiments on the flavor changing neutral current.


title: Strategy for the 1995 LEP Energy Scan

abstract:
  We propose a procedure to measure the Z$^{0}$ line shape and take full
advantage of the superb performance of the CERN $e^+e^-$ Collider LEP. A
precise determination of the total cross section at 5 energies is needed for a
model-independent analysis of the data and for a precision test of the QED
initial state radiation from the fully inclusive hadronic channel.


title: Radiation of Light Fermions in Heavy Fermion Production

abstract:
  The rate for the production of a pair of massive fermions in $e^+ e^-$
annihilation plus real or virtual radiation of a pair of massless fermions is
calculated analytically. The contributions for real and virtual radiation are
displayed separately. The asymptotic behaviour close to threshold and for high
energies is given in a compact form. These approximations provide arguments for
the appropriate choice of the scale in the ${\cal O}(\alpha)$ result, such that
no large logarithms remain in the final answer.


title: Wilson loop approach to the qqbar interaction problem

abstract:
  It is shown that the semirelativistic $q \bar{q}$ potential, the relativistic
flux tube model and a confining Bethe--Salpeter equation can be derived from
QCD first principles in a unified point of view.


title:
$FSI$ Corrections For Near Threshold Meson Production In Nucleon-Nucleon
  Collisions

abstract:
  A procedure is proposed which accounts for final state interaction
corrections for near threshold meson production in nucleon-nucleon scattering.
In analogy with the Watson-Migdal approximation, it is shown that in the limit
of extremely strong final state effects, the amplitude factorizes into a
primary production amplitude and an elastic scattering amplitude describing a
$3 \to 3$ transition. This amplitude determines the energy dependence of the
reaction cross section near the reaction threshold almost solely. The
approximation proposed satisfies the Fermi-Watson theorem and the coherence
formalism. Application of this procedure to meson production in nucleon-nucleon
scattering shows that, while corrections due to the meson-nucleon interaction
are small for s-wave pion production, they are crucial for reproducing the
energy dependence of the $\eta$ production cross section.


title: Confining Bethe--Salpeter equation in QCD

abstract:
  We derive a confining $ q \bar{q}$ Bethe--Salpeter equation starting from the
same assumptions on the Wilson loop integral already adopted in the derivation
of a semirelativistic heavy quark potential. We show that, by standard
approximations, an effective meson squared mass operator can be obtained from
our BS kernel and that, from this, by ${1\over m^2}$ expansion, the
corresponding Wilson loop potential is recovered, spin--dependent and
velocity--dependent terms included. We also show, that, on the contrary,
neglecting spin--dependent terms, relativistic flux tube model is reproduced.


title: Integrating out the Standard Higgs Field in the Path Integral

abstract:
  We integrate out the Higgs boson in the electroweak standard model at one
loop and construct a low-energy effective Lagrangian assuming that the Higgs
mass is much larger than the gauge-boson masses. Instead of applying
diagrammatical techniques, we integrate out the Higgs boson directly in the
path integral, which turns out to be much simpler. By using the
background-field method and the Stueckelberg formalism, we directly find a
manifestly gauge-invariant result. The heavy-Higgs effects on fermionic
couplings are derived, too. At one loop the $\log\MH$-terms of the heavy-Higgs
limit of the electroweak standard model coincide with the UV-divergent terms in
the gauged non-linear $\sigma$-model, but vertex functions differ in addition
by finite constant terms. Finally, the leading Higgs effects to some physical
processes are calculated from the effective Lagrangian.


title: Effective Action for the Quark-Meson Model

abstract:
  The scale dependence of an effective average action for mesons and quarks is
described by a nonperturbative flow equation. The running couplings lead to
spontaneous chiral symmetry breaking. We argue that for strong Yukawa coupling
between quarks and mesons the low momentum physics is essentially determined by
infrared fixed points. This allows us to establish relations between various
parameters related to the meson potential. The results for $f_\pi$ and
$\VEV{\olpsi\psi}$ are not very sensitive to the poorly known details of the
quark--meson effective action at scales where the mesonic bound states form.
For realistic constituent quark masses we find $f_\pi$ around $100\MeV$.


title: The $R_b$ Excess at LEP: Clue to New Physics at the TEVATRON?

abstract:
  If the $R_b$ excess at LEP is real, then any explanation in terms of
renormalizable loop corrections leads to important new decay modes of the $t$
quark and suppresses the $t \to bW$ branching ratio. In the two-Higgs-doublet
model, the branching ratio of $Z \to b \bar b$ + a light boson which decays
itself predominantly into $b \bar b$ is at least of order $10^{-4}$.


title: Magnetic moments of heavy baryons in the Skyrme model

abstract:
  We calculate the magnetic moments of heavy baryons in the Skyrme model in the
limit of infinite heavy quark mass. We show that the Skyrme model yields the
same limit as the nonrelativistic quark model when heavy vector mesons are
treated properly. The essential role of the magnetic moment coupling terms in
the electromagnetic interactions of heavy mesons is discussed.


title: NUMERICAL APPROACH TO TWO-LOOP THREE POINT FUNCTIONS WITH MASSES

abstract:
  Extending the method successful for one-loop integrals, the computation of
two-loop diagrams with general internal masses is discussed. For the two-loop
vertex of non-planar type, as an example, we show a calculation related to
\(Z^0\rightarrow t \bar t\) vertex.


title:
Gauge invariance, gauge-parameter independence and properties of Green
  functions

abstract:
  The application of the background-field method to the electroweak Standard
Model is reviewed and further explored. Special emphasis is put on questions of
gauge invariance and gauge-parameter (in-)dependence. Owing to the gauge
invariance of the background-field effective action, the vertex functions obey
simple Ward identities which imply important properties of the vertex
functions. Carrying out the renormalization in a way respecting
background-field gauge invariance leads to considerable simplifications. The
generalization of the background-field method to the non-linear realization of
the scalar sector of the Standard Model is illustrated. Furthermore, the
interplay between gauge independence of the S-matrix and Ward identities of
vertex functions is investigated. Finally, the Standard Model contributions to
the $S$, $T$, and $U$ parameters are calculated and discussed within the
background-field method.


title:
Effect of $K^{0}-\bar{K}^{0}$ Mixing on $CP$ Asymmetries in Weak Decays
  of $D$ and $B$ Mesons

abstract:
  Within the standard electroweak model we carry out an instructive analysis of
the effect of $K^{0}-\bar{K}^{0}$ mixing on $CP$ asymmetries in some weak decay
modes of $D^{\pm}$ and $\stackrel{(-)}{B}$$^{0}_{d}$ mesons. We point out that
a clean signal of $CP$ violation with magnitude of 2Re($\epsilon$) $\approx
3.3\times 10^{-3}$ can manifest in the semileptonic decays $D^{+}\rightarrow
l^{+}\nu^{~}_{l}K_{S}$ ($K_{L}$) vs $D^{-}\rightarrow
l^{-}\bar{\nu}^{~}_{l}K_{S}$ ($K_{L}$). The $CP$ asymmetries are also dominated
by 2Re($\epsilon$) in the two-body nonleptonic decays $D^{\pm} \rightarrow
(\pi^{\pm}, \rho^{\pm}, a^{\pm}_{1})+ (K_{S}, K_{L})$ and in the multi-body
processes $D^{\pm}\rightarrow \pi^{\pm}+n_{0}\pi^{0}+n_{\pm}
(\pi^{\pm}\pi^{\mp})+ (K_{S}, K_{L})$, where $n_{0}$ and $n_{\pm}$ are
integers. It is possible to observe such $CP$-violating signals with about
$10^{7}$ $D^{\pm}$ events at $\tau$-charm factories or hadron machines. Finally
we show that the $CP$ asymmetry induced by Re($\epsilon$) may compete with
those from $B^{0}_{d}-\bar{B}^{0}_{d}$ mixing and final-state interactions in
the semi-inclusive and exclusive decays $B_{d}\rightarrow X(c\bar{c})+(K_{S},
K_{L})$ on the $\Upsilon (4S)$ resonance.


title: On the Form Factors of the $D_{s}^{+}\to \phi\mu^{+}\nu_{\mu} decay

abstract:
  We apply the infinite mass effective theory, when a heavy quark mass tends to
infinity, and Chiral perturbation theory at the quark level, based on the
extended Nambu -- Jona -- Lasinio model with linear realization of chiral
$U(3)\times U(3)$ symmetry, to calculate the form factors of the
$D^{\,+}_{\,s}\to\phi~\mu^+~\nu_{\,\mu}$ decay up to the first order in current
$s$ -- quark mass. The theoretical results are compared with experimental data
and found to be in good agreement.


title: H-- Events in the ZEUS detectror

abstract:
  The supersymmetric left-right models suggest a production of doubly charged
Higgs particles. Still there is no evidence for the existence and only some
lower limits for their mass are present from the Z decay. Here we investigate
the possibility of observing the doubly electronic Higgs decay assuming a
M{H--}=50 Gev and M{H--}=100 Gev.The ZEUS detector


title: Models of Light Singlet Fermion and Neutrino Phenomenology

abstract:
  We suggest that a singlet fermion $S$ exists beyond the standard see-saw
structure. It mixes with light neutrinos via interactions with the right-handed
neutrino components, so that $\n_e \to S$ conversion solves the solar neutrino
problem. Supersymmetry endowed with R-symmetry is shown to give a natural
framework for existence, mass scale and mixing ($\sin^22\th_{es} \sim
(0.1-1.5)\cdot 10^{-2}$) of such a fermion. Models with an approximate
horizontal symmetry are constructed, which embed the fermion $S$ and explain
simultaneously solar, atmospheric, hot dark matter problems as well as may
predict the oscillation $\bar{\n}_\m \to \bar{\n}_e$ in the region of
sensitivity of KARMEN and LSND experiments.


title:
RELATIVISTIC CORRECTIONS TO THE ELECTROMAGNETIC AND AXIAL MOMENTS OF
  NUCLEI AND OTHER COMPOSITE SYSTEMS

abstract:
  We calculate the electromagnetic and axial nuclear moments of the deuteron
and triton as a function of their radius using a relativistic two-nucleon and
three-nucleon model formulated on the light-cone. The results also provide an
estimate of the nuclear binding corrections to helicity-dependent deep
inelastic scattering sum rules. At large nucleon radius, the moments are given
by the usual non-relativistic formulae modified by finite binding effects. At
small radius, the moments take the canonical values given by the generalization
of the Drell-Hearn-Gerasimov sum rule. In addition, as R-->0, the constituent
helicities become completely disoriented, and the Gamow-Teller matrix element
vanishes. Thus, in the pointlike limit MR-->0, the moments of a spin-one bound
states coincide with the canonical couplings of elementary spin-one bosons of
the Standard Model, mu=e/M, Q=-e/M^2, and g_A=0.


title: AN ALGORITHM FOR SMALL MOMENTUM EXPANSION OF FEYNMAN DIAGRAMS

abstract:
  An algorithm for obtaining the Taylor coefficients of an expansion of Feynman
diagrams is proposed. It is based on recurrence relations which can be applied
to the propagator as well as to the vertex diagrams. As an application, several
coefficients of the Taylor series expansion for the two-loop propagator and
two-loop non-planar vertex diagrams are calculated. The results of the
numerical evaluation of these diagrams using conformal mapping and Pade
approximants are given.


title:
Automatic Calculation of 2-loop Weak Corrections to Muon Anomalous
  Magnetic Moment

abstract:
  An automatic system to calculate two loop weak corrections to muon anomalous
magnetic moment is discussed. Diagrams are classified into eight types,
according to their topology. Adopting Civitanovi\'c-Kinoshita representation of
Feynman amplitude and using the topological property, the renormalization is
performed consistently by n-dimensional regularization method.


title: HEAVY QUARK PHOTOPRODUCTION IN THE SEMIHARD APPROACH AT HERA AND BEYOND

abstract:
  Processes of heavy quark photoproduction at HERA energies and beyond are
investigated using the semihard ($k_{\bot}$ factorization) approach. Virtuality
and longitudinal polarization of gluons in the photon - gluon subprocess as
well as the saturation effects in the gluon distribution function at small $x$
have been taken into account. The total cross sections, rapidity and $p_{\bot}$
distributions of the charm and beauty quark photoproduction have been
calculated. The results are compared with ZEUS experimental data for charm
photoproduction cross section.


title:
Saturation of counterterms by resonances in $K \to \pi e^{+} e^{-}$
  decays

abstract:
  The decays $K^{+} \rightarrow \pi^{+} e^{+} e^{-}$, $K_{S} \rightarrow
\pi^{0} e^{+} e^{-}$ and $K_{L} \rightarrow \pi^{0} e^{+} e^{-}$ are
reinvestigated within the framework of chiral perturbation theory. The
counterterms induced by strong, electromagnetic and weak interactions are
determined assuming the resonance exchange. The weak deformation model, the
factorization model and the large $N_{c}$ limit are used to create a weak
Lagrangian. It is found that the results of the first two approaches depend on
the $H_{1}$ coupling, defined in the effective chiral Lagrangian of the ${\it
O} (p^{4})$ order. The set of parameters used in the extended Nambu and
Jona-Lasinio model can accommodete $K^{+} \rightarrow \pi^{+} e^{+} e^{-}$
decay rate within the factorization approach. The CP violating $K_{L}
\rightarrow \pi^{0} e^{+} e^{-}$ decay rate is discussed.


title: Solar and atmospheric neutrino oscillations with three flavours

abstract:
  We analyze the solar and the atmospheric neutrino problems in the context of
three flavour neutrino oscillations. We assume a mass hierarchy in the vacuum
mass eigenvalues $\mu_3^2 \gg \mu_2^2 \geq \mu_1^2$, but make no approximation
regarding the magnitudes of the mixing angles. We find that there are small but
continuous bands in the parameter space where the constraints imposed by the
current measurements of $ \ {}^{71} Ga$, ${}^{37} Cl$ and Kamiokande
experiments are satisfied at $1 \sigma$ level. The allowed parameter space
increases dramatically if the error bars are enlarged to $1.6 \sigma$. The
electron neutrino survival probability has different energy dependence in
different regions of the parameter space. Measurement of the recoil electron
energy spectrum in detectors that use $\nu - e$ scattering may distinguish
between some of the allowed regions of parameter space. Finally we use the
results for the parameter space admitted by the solar neutrinos as an input for
the atmospheric neutrino problem and show that there exists a substantial
region of parameter space in which both problems can be solved.


title: On Gluon Radiation in $t \bar t$ Production and Decay

abstract:
  Understanding the pattern of gluon radiation in $t \bar t$ production
processes is important for making an accurate determination of the top mass
from the measurement of its decay products. In a recent paper we showed that
the exact matrix element and parton shower (HERWIG) calculations gave very
different results for the distribution of gluon jets in $t \bar t$ production
at the Tevatron $p \bar p$ collider. By repeating the calculation for the
simpler $e^+e^- \to b \bar b W^+W^-g$ process, we reveal even more dramatic
differences between the two approaches. We conclude that there are significant
differences in gluon radiation between HERWIG and the matrix element
calculation in regions of phase space where one would expect agreement.


title: The Role of Lambda(1405) in Kaon-Proton Interactions

abstract:
  S-wave $K^-p$ scattering into various channels near threshold are analyzed in
heavy-baryon chiral perturbation theory with $\Lambda (1405)$ introduced as an
independent field. This is the approach that predicted the critical density
$2<=\rho_c/\rho_0 <=3$ for negatively charged kaon condensation. We show that
chiral perturbation expansion treating the $\Lambda (1405)$ as elementary is
consistent with {\it all} threshold data including a double-charge-exchange
process suppressed at leading order of chiral expansion in the absence of the
$\Lambda (1405)$. We also discuss S-wave $K^+ p$ scattering phase shifts at low
energy.


title: Diffractive Deep-Inelastic Scattering

abstract:
  Diffractive deep inelastic events with a large rapidity gap are analyzed by
using a Regge model for the pomeron flux and a gluonic content for the pomeron.
Contrary to the expectations, the simplest assumption for the pomeron
trajectory gives the best agreement with the data on the ratio of diffractive
to the total number of events. In this case the main properties of the model
are described by an analytic expression.


title: CP Violation in $D^0-\overline{D^0}$Mixing

abstract:
  The existence of $D^0-\overline{D^0}$ mixing at a detectable level requires
new physics, which effectively yields a $\Delta c = 2$ superweak interaction.
In general this interaction may involve significant CP violation. For small
values of the mixing it may be much easier to detect the CP-violating part of
the mixing than the CP-conserving part.


title: THE STRUCTURE FUNCTION F_2^{\gamma}(x,Q^2) AT LEP2

abstract:
  The unique nature of the photon can be investigated in hitherto unexplored
kinematic regions at LEP2. We discuss the theoretical significance of deep
inelastic measurements and present a prescription that allows a theoretically
and experimentally sensible separation of the so-called `anomalous' and
`hadronic' components of the target photon. We perform preliminary studies
regarding the ability to reconstruct the $\gamma^* \gamma$ CM energy (and hence
$x$) and the usefulness of the easier to measure electron structure function.


title: Bound states of scalar bosons in extensions of the Standard Model

abstract:
  We explore systematically, in a general two Higgs doublet model, the
possibility, that bound systems of scalar bosons do exist. We find a wide
region of parameter space in the scalar potential for which S-wave bound states
of Higgs bosons do indeed exist. On the contrary we show that the Minimal
Supersimmetric Standard Model does not admit such bound systems.


title: Parton Hadron Duality in nonleptonic B hadron decays

abstract:
  Assuming so called global duality we argue that it is very likely that local
duality needed to obtain results for the hadronic width of heavy meson decays
within the $1/m_Q$ expansion holds. Hence, if the discrepancy between
experiment and the theory concerning charm counting, the semileptonic branching
fraction and the lifetimes of $b$ hadrons persist, it may be taken as a hint at
some qualitatively new effect in (nonperturbative) QCD or even as a new
physics.


title: Recent Progress in the Heavy Quark Theory

abstract:
  Some recent developments in the heavy quark theory are briefly reviewed. The
main emphasis is put on interrelation between HQET and OPE. The notion of
duality and deviations from duality are discussed in detail.


title:
Chirally Extended QCD or An Asymptotically Free Chiral Linear Sigma
  Model With Quarks Coupled to Gluons

abstract:
  We show that the quark (not nucleon) based chiral linear $\sigma$ model which
receives strong support as a mean field theory for the strong interactions can
actually be made asymptotically free by coupling to gluons. It has the further
bonus of providing confinement.Alternatively, this theory is QCD that is
chirally extended by the addition of a $(\sigma,\pi)$ chiral multiplet. It
could therefore be a candidate theory for the strong interactions which is
somewhat different from QCD.


title: Spin--1/2 Particle in Gravitational Field of a Rotating Body

abstract:
  Effective Lagrangian describing gravitational source spin-particle spin
interactions is given. Cosmological and astrophysical consequences of such
interaction are examined. Although stronger than expected, the spin-spin
interactions do not change any cosmological effect observed so far. They are
important for background primordial neutrinos.


title: BRS Symmetry in Connes' Non-commutative Geometry

abstract:
  We extend the BRS and anti-BRS symmetry to the two point space of Connes'
non-commutative model building scheme. The constraint relations are derived and
the quantum Lagrangian constructed. We find that the quantum Lagrangian can be
written as a functional of the curvature for symmetric gauges with the BRS,
anti-BRS auxiliary field finding a geometrical interepretation as the extension
of the Higgs scalar.


title:
Julian Schwinger: Source Theory and the UCLA Years--- From Magnetic
  Charge to the Casimir Effect

abstract:
  Julian Schwinger began the construction of Source Theory in 1966 in response
to the then apparent failure of quantum field theory to describe strong
interactions, the physical remoteness of renormalization, and the utility of
effective actions in describing chiral dynamics. I will argue that the source
theory development was not really so abrupt a break with the past as Julian may
have implied, for the ideas and techniques in large measure were present in his
work at least as early as 1951. Those techniques and ideas are still of
fundamental importance to theoretical physics, so much so that the designation
``source theory'' has become superfluous. Julian did a great deal of innovative
physics during the last 30 years of his life, and I will touch on some of the
major themes. The impact of much of this work is not yet apparent. (Invited
talk at Washington APS/AAPT meeting)


title:
Puzzle in the Charmed $D_s$ meson decays into pions: Could the light
  quarks be not so light?

abstract:
  The inclusive decay rate into pions of the charmed $D_s$ meson is
surprisingly larger than estimates expected from the $W$ annihilation, adopting
commonly used values of current-algebra up and down quark masses. We then go
beyond this tree diagram and consider possible QCD effects that might cause
such a large rate. There are two; the first one is related to the spectator
decay $ c{\bar s} \rightarrow s{\bar s} + u {\bar d}$ followed by $ s {\bar s}
\rightarrow d{\bar d}~,~ u{\bar u}$ via two-gluon exchange box diagram. The
second one is a gluon emission in weak annihilation for which the usual
helicity suppression is vitiated: $D_s\rightarrow W+g$ followed by $
W\rightarrow u {\bar d},~ g\rightarrow d{\bar d},~u{\bar u}$. These two
contributions, however, turn out to be insufficient to explain data, implying
that the puzzle could be understood if the up, down quarks have higher mass
values. Furthermore, on the basis of experimental informations on the spectral
function $\rho_{3\pi}(Q^2)$ deduced from the exclusive $ D_s \rightarrow 3\pi$
mode, the QCD sum rules also point to a higher mass for light quarks.


title: Dynamical mass matrices from effective superstring theories

abstract:
  We analyze the general structure of the fermion mass matrices in effective
superstrings. They are generically given at low energy by non-trivial functions
of the gauge singlet moduli fields. Interesting structures appear in particular
if they are homogeneous functions of zero degree in the moduli. In this case we
find Yukawa matrices very similar to the ones obtained by imposing a $U(1)$
family symmetry to reproduce the observed hierarchy of masses and mixing
angles. The role of the $U(1)$ symmetry is played here by the modular symmetry.
Explicit orbifold examples are given where realistic quark mass matrices can be
obtained. Finally, a complete scenario is proposed which generates the observed
hierarchies in a dynamical way.


abstract:
  This is a report of the Electroweak Symmetry Breaking and Beyond the Standard
Model Working Group which was prepared for the Division of Particles and Fields
Committee for Long Term Planning. We study the phenomenology of electroweak
symmetry breaking and attempt to quantify the "physics reach" of present and
future colliders. Our investigations encompass the Standard Model (with one
doublet of Higgs scalars) and approaches to physics beyond the Standard Model.
These include models of low energy supersymmetry, technicolor and other
approaches to dynamical electroweak symmetry breaking, and a variety of
extensions of the Standard Model with new particles and interactions ({\it
e.g.}, non-minimal Higgs sectors, new gauge bosons and/or exotic fermions, {\it
etc.}). Signals of new physics in precision measurements arising from virtual
processes (which can result, for example, in ``anomalous'' couplings of
Standard Model particles) are also considered. Finally, we examine experimental
issues associated with the study of electroweak symmetry breaking and the
search for new physics at present and future hadron and $e^+e^-$ colliders.


title: Inclusive Charm Production at HERA and the Charm Content of the Photon

abstract:
  We calculate the contribution to inclusive high tranverse momentum ($p_T$)
charm production at HERA from the excitation of charm in the photon. At large
values of \pt\ the results of such a calculation, in the structure function
language, will be more reliable as it sums the large logs, $\log(p_T^2/m_c^2)$,
as opposed to calculating the contribution of the $2 \to 3 $ subprocess in
fixed order of perturbation theory. We find that this contribution is large and
comparable to the contribution from $\gamma g$ fusion production of charm.
Suitable cuts on the rapidity of the `away-side' large \pt\ jet allow a very
neat separation between the contributions from the excitation process and from
pair-production. We further find that including this excitation contribution we
can reproduce the measured inclusive $D^*$ and $\mu$ cross--sections measured
by the ZEUS and H1 collaborations respectively, in a LO calculation.


title: PRODUCTION OF $B_c$ MESONS IN HADRONIC COLLISIONS

abstract:
  We investigate hadroproduction of $B_c$ mesons from initial gluons using QCD
perturbation theory and nonrelativistic bound state approximations. Our results
obtained by two completely independent calculations are confronted with
existing results which contradict each other. Moreover, we examine the
approximation based on heavy quark fragmentation and determine the range of
validity of it. Predictions for cross sections and differential distributions
at Tevatron and LHC energies are presented.


title:
Search for $\eta_{c}^{'}$ and $h_{c} (^{1}P_{1})$ states in the $e^+
  e^-$ annihilations

abstract:
  Productions and decays of spin-singlet $S,P-$wave charmonium states,
$\eta_{c}^{'}$ and $h_{c} (^{1}P_{1})$, in the $e^+ e^-$ annihilations are
considered in the QCD multipole expansion with neglecting nonlocality in time
coming from the color-octet intermediate states. Our approximation is opposite
to the Kuang-Yan's model. The results are $B (\psi^{'} \rightarrow h_{c} +
\pi^{0}) \approx 0.3 \%$, $B ( \psi^{'} \rightarrow \eta^{'} + \gamma ) \approx
0.34 \%$, $\Gamma (\eta_{c}^{'} \rightarrow J/\psi + \gamma) \approx 0.26$ keV
and $\Gamma (h_{c} \rightarrow J/\psi + \pi^{0}) \approx 2.5$ keV.


title: Magnetic Field Dependence of Muonium-antimuonium Conversion

abstract:
  We study the magnetic field dependence of muonium--antimuonium conversion
induced by neutral (pseudo)scalar bosons. Only the $SS$ operator contributes to
the conversion of polarized muonium, but it gets quenched by a magnetic field
of strength 0.1 Gauss or stronger. Conversion induced by $SS$ couplings for
unpolarized muonium is independent of magnetic field. Magnetic fields of 0.1
Tesla or stronger starts to suppress conversion induced by $PP$ interactions in
the lowest Breit-Rabi level, but gets partially compensated by a rise in
conversion probability in the other unpolarized level. The effects of $(S\mp
P)(S\mp P)$ and $(S\mp P)(S\pm P)$ operators behave in the same way as $(V\mp
A)(V\mp A)$ and $(V\mp A)(V\pm A)$ operators, respectively.


title:
Atmospheric Neutrino Oscillations among Three Neutrino Flavors and
  Long-Baseline Experiments

abstract:
  Anticipating future long-baseline neutrino experiments to search for neutrino
oscillations in various oscillation channels, we have analyzed the atmospheric
neutrino data in the framework of a model with mixing of three massive neutrino
fields that can accommodate the data of solar neutrino experiments. The
oscillations of atmospheric and terrestrial neutrinos are described in this
model by three parameters: $ \Delta m^2 $ and the squared moduli of two
elements of the mixing matrix, $ | U_{e3} |^2 $ and $ | U_{\mu3} |^2 $, which
determine the amplitudes of oscillations among all active neutrinos. The
results of the analysis of the atmospheric neutrino data are presented in the
form of allowed regions in the plane of the two parameters oscillation
amplitude and $ \Delta m^2 $ for all oscillation channels to be investigated in
the future long-baseline oscillation experiments.


title:
Superfield Derivation of the Low-Energy Effective Theory of Softly
  Broken Supersymmetry

abstract:
  We analyze the soft supersymmetry breaking parameters obtained in grand
unified theories after integrating out the heavy GUT-states. The superfield
formalism greatly simplifies the calculations and allows us to derive the
low-energy effective theory in the general case of non-universal and
non-proportional soft terms by means of a few Feynman diagrams. We find new
contributions not considered before. We discuss the implications for the
destabilization of the gauge hierarchy, flavor violating processes and the
non-unification of sparticle masses in unified theories.


title: Tau Polarimetry with Multi Meson States

abstract:
  It is demonstrated that the analyzing power of multi-meson final states in
semileptonic $\tau$ decays with respect to the $\tau$ spin is equal and maximal
for all decay modes.


title: Precision tests of the MSSM

abstract:
  We present the results of a first global fit to the electroweak observables
in the MSSM. The best fit selects either very low or very large values of
~$\tan\beta$ ~and, correspondingly, chargino (higgsino--like) and stop or the
~$CP-$odd Higgs boson are within the reach of LEP 2. Moreover, the best fit
gives ~ $\alpha_s(M_Z)=0.118^{+0.005}_{-0.010}$, ~which is lower than the one
obtained from the SM fits. The overall fit is excellent ~ ($\chi^2=7.2$ ~for 15
d.o.f. as compared to ~$\chi^2=11$ ~in the SM). Those results follow from the
fact that in the MSSM one can increase the value of ~
$R_b\equiv\Gamma_{Z^0\to\bar bb}/\Gamma_{Z^0\to hadrons}$ ~ {\it without}
modyfying the SM predictions for other observables.