title:
Chiral scalar fields, electroweak SU(2)left x U(1) and the quantization
  of the electric charge

abstract:
  I study the scalar representations of the electroweak group of the Standard
Model, with a special emphasis on their chiral properties and on their
behaviour by the discrete symmetries P and CP. A gauge theory for J=0 mesons
naturally springs out, together with a new approach to the question of the
electroweak violation of CP. When acting in the 4-dimensional space of states
spanned by the special representations under scrutiny in this paper, the
electric charge appears as one of the three generators of the diagonal SU(2)
and its eigenvalues are consequently quantized.


title: Chaotic Dynamics of SU(2) Gauge Fields in the Presence of Static Charges

abstract:
  We have found in numerical simulations that the chaoticity of the classical
hamiltonian lattice SU(2) gauge theory is reduced in the presence of static
charges at the same total energy. The transition from strongly to weakly
chaotic behavior is rather sudden at a critical charge strength.


title:
Generalized Gaussian Effective Potential: Second Order Thermal
  Corrections

abstract:
  We discuss the finite temperature generalized Gaussian effective potential.
We put out a very simple relation between the thermal corrections to the
generalizedGaussian effective potential and those of the effective potential.
We evaluate explicitly the second order thermal corrections in the case of the
selfinteracting scalar field in one spatial dimension.


title:
Extraction of the pion distribution amplitude from polarized muon pair
  production

abstract:
  We consider the production of muon pairs from the scattering of pions on
longitudinally polarized protons. We calculate the cross section and the single
spin asymmetry for this process, taking into account pion bound state effects.
We work in the kinematic region where the photon has a large longitudinal
momentum fraction, which allows us to treat the bound state problem
perturbatively. Our predictions are directly proportional to the pion
distribution amplitude. A measurement of the polarized Drell-Yan cross section
thus allows the determination of the shape of the pion distribution amplitude.


title: A Supersymmetric Resolution of the KARMEN Anomaly

abstract:
  We consider the hypothesis that the recently reported anomaly in the time
structure of signals in the KARMEN experiment is due to the production of a
light photino (or Zino) which decays radiatively due to violation of
$R$-parity. Such a particle is shown to be consistent with all experimental
data and with cosmological nucleosynthesis. There are difficulties with
constraints from SN~1987A but these may be evaded if squarks are non-degenerate
in mass.


title: Heavy-Quark Correlations in Direct Photon-Photon Collisions

abstract:
  In two-photon collisions at LEP2 and a future $e^+e^-$ linear collider heavy
quarks (mainly charm) will be pair-produced rather copiously. The production
via direct and resolved photons can be distinguished experimentally via a
remnant-jet tag. We study correlations of the heavy quarks at next-to-leading
order in QCD in the direct channel, which is free from phenomenological parton
densities in the photon. These correlations are therefore directly calculable
in perturbative QCD and provide a stringent test of the production mechanism.


title:
Relativistic and Binding Energy Corrections To Heavy Quark Fragmentation
  Functions

abstract: Withdrawn; originally put in incomplete form without permission


title: Beyond The Colour-Singlet Model For Inelastic J/\psi Photoproduction

abstract:
  Bound-state corrections to $J/\psi$ production from almost real photons are
calculated in the colour-singlet model. A systematic, gauge-invariant, theory
  of hard quarkonium processes is used upto $O(v^2)$, where $v$ is the relative
velocity of the quarks. The internal structure of the meson is characterised by
two parameters, $\epsilon_B/M$ and $\nabla^2 \phi(0)/M^2 \phi(0)$, in addition
to the usual wavefunction at the origin $\phi(0)$. These parameters are
constrained to be consistent with measured leptonic decay of the $J/\psi$ and
hadronic and radiative decays of $\eta_c$.


title: New Aspects of Reheating

abstract:
  The reheating stage in post-inflationary cosmologies is reanalyzed. New
techniques from non-equilibrium quantum field theory allow a consistent
derivation of the equation of motion including the non-linearity of the
dynamics. These offer a rationale for the elementary theory of reheating based
on single particle decay which is seen to be valid only in the linear regime of
coherent oscillations of the scalar field. A new non-perturbative mechanism of
induced amplification of quantum fluctuations is introduced and studied in
detail, both analytically and numerically. This is a non-linear mechanism that
is typically a far more efficient way of transfering energy out of the zero
mode and into production of lighter particles than single particle decay.
Thermalization is discussed and we estimate the reheating temperature to be of
the order of the inflaton mass, thus providing a potential solution to the
Polonyi and moduli problems.


title:
Radiative $B^{*}B\gamma$ and $D^{*}D\gamma$ coupling constants in light
  cone QCD sum rules

abstract:
  The radiative decays $ B^{*} (D^{*})\to B(D) \gamma$ are investigated in the
framework of light cone QCD sum rules. The transition amplitude and decay rates
are estimated.It is shown that our results on branching ratios of D meson
decays are in good agreement with the existing experimental data.


title:
Angular distributions and lifetime differences in $B_s \to J/\psi \phi$
  decays

abstract:
  The strange $B$ meson $B_s \equiv \bar b s$ and its charge-conjugate $\bar
B_s \equiv b \bar s$ are expected to mix with one another in such a way that
the mass eigenstates $B_s^H$ (``heavy'') and $B_s^L$ (``light'') may have a
perceptible lifetime difference of up to 40\%, with the CP-even eigenstate
being shorter-lived. A simple transversity analysis permits one to separate the
CP-even and CP-odd components of $B_s \to J/\psi \phi$, and thus to determine
the lifetime difference. The utility of a similar analysis for $B^0 \to J/\psi
K^{*0}$ is noted.


title:
Possible explanation of Zbb vertex anomaly in one-family technicolor
  models

abstract:
  In technicolor theories a large radiative correction to the Zbb vertex
generally emerges, because of the large top quark mass and SU(2)_L gauge
symmetry. The correction can give us an explanation for the deviation of the
experimental value of R_b from the standard model prediction. However,
generally the T parameter becomes unacceptably large. We show that in the
one-family technicolor model recently proposed by the authors all the S, T, and
U parameters can be consistent with the experimental bounds while the observed
anomaly of R_b is naturally explained.


title: Chiral perturbation theory analysis of baryon temperature mass shifts

abstract:
  We compute the finite temperature pole mass shifts of the octet and decuplet
baryons using heavy baryon chiral perturbation theory and the 1/N_c expansion,
where N_c is the number of QCD colors. We consider temperatures of the order of
the pion mass m_\pi, and truncate the chiral and 1/N_c expansions assuming that
m_\pi \sim 1/N_c. There are three scales in the problem: the temperature T, the
pion mass m_\pi, and the octet--decuplet mass difference. Therefore, the result
is not simply a power series in T. We find that the nucleon and \Delta
temperature mass shifts are opposite in sign, and that their mass difference
changes by 20% in the temperature range 90 MeV < T < 130 MeV, that is the range
where the freeze out in relativistic heavy ion collisions is expected to occur.
We argue that our results are insensitive to the neglect of 1/N_c- supressed
effects; the main purpose of the 1/N_c expansion in this work is to justify our
treatment of the decuplet states.


title: Unitary Limit on $K^0_L \to \mu^+ \mu^-$ and the Top Quark Mass

abstract:
  A brief overview of the recent measurements of the branching ratio of the
rare $K_L^0 \to \mu^+ \mu^-$ decay in the context of their agreement with the
Standard Model (SM) is given. It is shown that KEK result well correlates with
the SM and B-physics, whereas the BNL results are in conflict with the SM with
the heavy top quark.


title: Formulations of spin 1 resonances in the chiral lagrangian

abstract:
  Equivalence of the hidden local symmetry formulation with non-minimal
interactions and the anti-symmetric tensor field method of $\rho$ and $a_1$
mesons in the chiral lagrangian is shown by using the auxiliary field method.
Violation of the KSRF I relation, which becomes important in the application of
chiral lagrangian to {\em non QCD-like} technicolor models can be parametrized
by non-minimal coupling in the hidden local symmetry formalism keeping low
energy theorem of hidden local symmetry. We also obtain explicit correspondence
of parameters in both formulations.


title:
CP-odd interaction of quarks and SU(2) gauge bosons with scalar field
  background in Kobayashi-Maskawa model

abstract:
  CP-violating interaction of quarks and W-bosons with the scalar field
background is studied in the Kobayashi-Maskawa with with Standard Model content
of flavors and with additional heavy generation of fermions. The corresponding
two-loop induced formfactors are calculated at zero temperature. The results
are generalized at large momentum transfers to take into account the
CP-violating effects in the Higgs boson decay. The inclusion of this
interaction into the scheme of adiabatic baryogenesis at the temperature of
electroweak phase transition suffers from the uncertainties come from the poor
knowledge of the vacuum condensate value triggering baryon number violating
processes. It is shown, however, that even in the most favorable assumptions
the Standard Model with four generations cannot produce enough C and CP
violation for the explanation of the observable excess of baryons in the
Universe.


title: Heavy-flavored strange pentaquark seems not to exist

abstract:
  Possible existence of a molecular-type heavy-flavored strange pentaquark is
considered. No narrow state of such a type is shown to exist.


title: Theoretical Progress in QCD at small $x$

abstract:
  I review a recent progress in understanding the Regge asymptotics in
perturbative QCD including the behaviour of the structure functions of DIS at
small Bjorken $x$.


title:
Standard Model Criticality Prediction: Top mass 173 +/- 5 GeV and Higgs
  mass 135 +/- 9 GeV

abstract:
  Imposing the constraint that the Standard Model effective Higgs potential
should have two degenerate minima ( vacua), one of which should be - order of
magnitudewise - at the Planck scale, leads to the top mass being 173 +/- 5 GeV
and the Higgs mass 135 +/- 9 GeV. This requirement of the degeneracy of
different phases is a special case of what we call the multiple point
criticality principle. In the present work we use the Standard Model all the
way to the Planck scale, and do not introduce supersymmetry or any extension of
the Standard Model gauge group. A possible model to explain the multiple point
criticality principle is lack of locality fundamentally.


title: QED in strong fields

abstract:
  We discuss the status of atomic physics in strong field. We focus on the
problem of electron-positron lines observed in heavy-ion collisions and on QED
effects, calculated in strong Coulomb fields, especially Delbr\"uck-scattering.
We discuss the similarities and differences between these effects and
channeling respectively beamstrahlung. We investigated the prospects for
photon-channeling, calculated channeling from first principles on the basis of
the Dirac equation, and determined the rate for electron-positron pair
production in the collision of two high-energy particle pulses.


title: Theory Aspects of Double-Spin Asymmetries in Proton-Nucleon Collisions

abstract:
  The study of two spin asymmetries in hadron-hadron collisions probes the
details of fundamental particle interactions in ways infeasible to machines
with unpolarized collisions. Within reach is how the proton spin is distributed
among its constituents through $\Delta G$ and $\Delta\bar{q}$. Measuring
couplings, furthering our understanding jet structure and uncovering new
physics are all among the possibilities available at polarized colliders. Spin
physics may also deepen our understanding of higher twist behavior and the
transition between perturbative and nonperturbative physics. An overview of the
double spin physics is presented in this report. (Talk presented during the
Workshop on the ``Prospects of Spin Physics at HERA'' held at DESY-Zeuthen,
Germany, 28-31 August 1995.)


title: Light-Cone Quantization and QCD Phenomenology

abstract:
  In principle, quantum chromodynamics provides a fundamental description of
hadronic and nuclear structure and dynamics in terms of their elementary quark
and gluon degrees of freedom. In practice, the direct application of QCD to
reactions involving the structure of hadrons is complex because of the
interplay of nonperturbative effects such as color confinement and multi-quark
coherence. A crucial tool in analyzing such phenomena is the use of
relativistic light-cone quantum mechanics and Fock state methods to provide
tractable and consistent treatments of relativistic many-body systems. We begin
with a brief introduction to light-cone field theory, stressing how it may
allow the derivation of a constituent picture, analogous to the constituent
quark model. The Fock state representation includes all quantum fluctuations of
the hadron wavefunction, including far off-shell configurations such as
intrinsic charm and, in the case of nuclei, hidden color. The Fock state
components of the hadron with small transverse size, which dominate hard
exclusive reactions, have small color dipole moments. Thus QCD predicts minimal
absorptive corrections, i.e., color transparency for quasi-elastic exclusive
reactions in nuclear targets at large momentum transfer. In other applications,
such as the calculation of the axial, magnetic, and quadrupole moments of light
nuclei, the QCD Fock state description provides new insights which go well
beyond traditional hadronic and nuclear physics.


title:
Perturbative QCD predictions for the small $x$ behaviour of unpolarized
  and polarized deep inelastic scattering structure functions

abstract:
  The perturbative QCD predictions for the small $x$ behaviour of the nucleon
structure functions $F_{2,L}(x,Q^2)$ and $g_1(x,Q^2)$ are summarized. The
importance of the double logarithmic terms for the small $x$ behaviour of the
spin structure function $g_1(x,Q^2)$ is emphasised. These terms correspond to
the contributions containing the leading powers of $\alpha_s ln(1/x)^2$ at each
order of the perturbative expansion. In the non-singlet case they can be
approximately accounted for by the ladder diagrams with quark (antiquark)
exchange. We solve the corresponding integral equation with the running
coupling effects taken into account and present estimate of the effective slope
controlling the small $x$ behaviour of the non-singlet spin structure function
$g_1(x,Q^2)$ of a nucleon.


title: Solution to the Strong CP Problem: Supersymmetry with Parity

abstract:
  There is a natural solution to the strong CP problem in the Minimal
Supersymmetric Standard Model if it arises from a parity symmetric theory which
is spontaneously broken to MSSM at Planck, GUT or intermediate scales. The
strong CP phase is zero at the tree level and is not induced to two loops. The
SUSY phase problems are also solved. The universal soft SUSY breaking
parameters A, B, \mu, m_{1/2} are all automatically real and the only
additional CP violation effects of the low-energy MSSM are characterized by a
Hermitian squark mass matrix whose phases depend on the CKM phase. Cases with
non-universal boundary conditions are also considered.


title: Gauged Yukawa Matrix Models and 2-Dimensional Lattice Theories

abstract:
  We argue that chiral symmetry breaking in three dimensional QCD can be
identified with N\'eel order in 2-dimensional quantum antiferromagnets. When
operators which drive the chiral transition are added to these theories, we
postulate that the resulting quantum critical behavior is in the universality
class of gauged Yukawa matrix models. As a consequence, the chiral transition
is typically of first order, although for a limited class of parameters it can
be second order with computable critical exponents.


title: Implications of Abelian Extended Gauge Structures From String Models

abstract:
  Within a class of superstring vacua which have an additional non-anomalous
$U(1)'$ gauge factor, we address the scale of the $U(1)'$ symmetry breaking and
constraints on the exotic particle content and their masses. We also show that
an extra gauge $U(1)'$ provides a new mechanism for generating a naturally
small effective $\mu$ term. In general, existing models are not consistent with
all phenomenological constraints; however, they do provide a testing ground to
address the above issues, yielding a set of concrete scenarios. Under the
assumptions that the spontaneous $U(1)'$ breaking takes place in the observable
sector and that the supersymmetry breaking scalar mass square terms are
positive at the string scale, the breaking of $U(1)'$ symmetry is radiative. It
can take place when the appropriate Yukawa couplings of exotic particles are of
order one, which occurs for $Z_2\times Z_2$ fermionic orbifold constructions at
symmetric points of moduli space. The $Z'$ mass is either of ${\cal O}(M_Z)$,
when the symmetry breaking is due to a single standard model singlet, or is of
a scale intermediate between the string and electro-weak scales, determined by
the radiative corrections (or by competing non-renormalizable operators), when
the breaking is due to two or more mirror-like singlets. In the former case,
the $M_{Z'}/M_Z$ hierarchy achievable without excessive fine tuning is within
future experimental reach.


title: Reconstructed CKM Matrices

abstract:
  We construct quark mixing matrices within a group theoretic framework which
is easily applicable to any number of generations. Familiar cases are retrieved
and related, and it is hoped that our viewpoint may have advantages both
phenomenologically and for constructing underlying mass matrix schemes.


title: The Two-Nucleon Potential from Chiral Lagrangians

abstract:
  Chiral symmetry is consistently implemented in the two-nucleon problem at
low-energy through the general effective chiral lagrangian. The potential is
obtained up to a certain order in chiral perturbation theory both in momentum
and coordinate space. Results of a fit to scattering phase shifts and bound
state data are presented, where satisfactory agreement is found for laboratory
energies up to about 100 Mev.


title: Particle Production and Gravitino Abundance after Inflation

abstract:
  Thermal history after inflation is studied in a chaotic inflation model with
supersymmetric couplings of the inflaton to matter fields. Time evolution
equation is solved in a formalism that incorporates both the back reaction of
particle production and the cosmological expansion. The effect of the
parametric resonance gives rise to a rapid initial phase of the inflaton decay
followed by a slow stage of the Born term decay. Thermalization takes place
immediately after the first explosive stage for a medium strength of the
coupling among created particles. As an application we calculate time evolution
of the gravitino abundance that is produced by ordinary particles directly
created from the inflaton decay, which typically results in much more enhanced
yield than what a naive estimate based on the Born term would suggest.


title:
Structure of Pomeron Couplings and Single-Spin Asymmetry in Diffractive
  $Q \bar Q$ Production

abstract:
  Transverse single spin asymmetry in polarized diffractive $Q \bar Q$
production is calculated. It is shown that this asymmetry depends strongly on
the spin structure of the pomeron coupling, which permits one to study the
pomeron couplings properties in future polarized experiments.


title:
The Dimensionally Reduced Effective Theory for Quarks in High
  Temperature QCD

abstract:
  We show that QCD undergoes dimensional reduction at high temperatures also in
the quark sector. In the kinematic region relevant to screening physics, where
the lowest Matsubara modes are close to their ``mass-shells'', all static
Green's functions involving both quarks and gluons, are reproducible in the
high-$T$ limit by a renormalizable three dimensional Lagrangian up to order
$\tilde{g}^2(T)\sim 1/ln T$. This three dimensional theory only contains
explicitly the lightest bosonic and fermionic Matsubara modes, while the
heavier modes correct the tree-level couplings and generate extra local
vertices. We also find that the quark degrees of freedom that have been
retained in the reduced theory are nonrelativistic in the high-$T$ limit. We
then improve our result to order $\tilde{g}^4(T)$ through an explicit
nonrelativistic expansion, in the spirit of the heavy quark effective theory.
This effective theory is relevant for studying QCD screening phenomena with
observables made from quarks, e.g. mesonic and baryonic currents, already at
temperatures not much higher than the chiral transition temperature $T_c$.


title: Inclusive Heavy-Flavor Production from Nuclei

abstract:
  We describe a light-cone wave function formulation for hadroproduction of
heavy-flavors at high energies. At moderate values of $x_F$ heavy-flavor
production can be viewed as a diffractive excitation of heavy quark-antiquark
Fock states, present in the interacting gluon from the projectile. The approach
developed here is well suited to address coherence effects in heavy-quark
production from nuclei at small values of $x_{t} \lsim 0.1\cdot A^{-1/3}$.


title:
QCD corrections to the decay $H^+ \to t \bar{b}$ in the Minimal
  Supersymmetric Standard Model

abstract:
  We present a complete calculation of the QCD corrections (of the order
$\alpha_s$) to the width of the decay $H^+ \to t \bar{b}$ within the Minimal
Supersymmetric Standard Model. We find that the QCD corrections are quite
important, and that the supersymmetric QCD corrections (due to gluino, stop and
sbottom exchange) can be comparable to or even larger than the standard QCD
corrections in a large region of the supersymmetric parameter space. This is
mainly due to the effect of large left-right mixings of stop and sbottom. This
could significantly affect the phenomenology of the $H^+$ search.


title:
Large Transverse Momentum Jet Production and the Gluon Distribution
  Inside the Proton

abstract:
  The CDF experiment has reported an excess of high-$p_t$ jets compared to
previous next-to-leading order QCD expectations. Before attributing this to new
physics effects, we investigate whether these high-$p_t$ jets can be explained
by a modified gluon distribution inside the proton. We find enough flexibility
in a global QCD analysis including the CDF inclusive jet data to provide a
25-35\% increase in the jet cross sections at the highest $p_t$ of the
experiment. Two possible sets of parton distributions are presented, and the
effects of these on other existing data sets are presented. Further theoretical
and experimental work needed to clarify unresolved issues is outlined.


title:
Domain Structure of a Disoriented Chiral Condensate From a Wavelet
  Perspective

abstract:
  We present a novel method for studying the formation of a disoriented chiral
condensate (DCC) in high-energy hadronic and heavy-ion collisions utilizing a
discrete wavelet transformation. Due to its salient feature of space-scale
locality, the discrete wavelet proves to be very effective in probing physics
simultaneously at different locations in phase space and at different scales.
We show that the probability distributions of the neutral pion fraction for
various rapidity-bin sizes have distinctive shapes in the case of a DCC and
exhibit a delay in approaching the Gaussian distribution required by the
Central Limit Theorem. We find the wavelet power spectrum for a DCC to exhibit
a strong dependence on the scale while an equilibrium system and the standard
dynamical models such as HIJING have a flat spectrum.


title: Analysis of the Hadronic Light-by-Light Contributions to the Muon $g-2$

abstract:
  We calculate the hadronic light-by-light contributions to the muon $g-2$. We
use both $1/N_c$ and chiral counting to organize the calculation. Then we
calculate the leading and next-to-leading order in the $1/N_c$ expansion low
energy contributions using the Extended Nambu--Jona-Lasinio model as hadronic
model. We do that to all orders in the external momenta and quark masses
expansion. Although the hadronic light-by-light contributions to muon $g-2$ are
not saturated by these low energy contributions we estimate them
conservatively. A detailed analysis of the different hadronic light-by-light
contributions to muon $g-2$ is done. The dominant contribution is the twice
anomalous pseudoscalar exchange diagram. The final result we get is $a_\mu^{\rm
light-by-light}= (-9.2\pm3.2 ) \cdot 10^{-10}$. This is between two and three
times the expected experimental uncertainty at the forthcoming BNL muon $g-2$
experiment.


title: Single Leptoquark Production at TeV Energy $\gamma p$ Colliders

abstract:
  The resolved and direct photon contributions to the single leptoquark (L)
production process $\gamma p\rightarrow L e$ are analysed for both scalar (S)
and vector (V) leptoquarks in detail. It is shown that resolved photon
contribution dominates for $M_{L}\leq 300 GeV$. For $M_{V}\geq 1 TeV$ and
$M_{S}\geq 0.5 TeV$ cross section is completely determined by the direct photon
conribution. The vector leptoquarks are discussed for both gauge- and non-gauge
cases seperately.


title: Heavy Quarkonium Photoproduction at HERA and Charm Content of the Photon

abstract:
  A study of the $\J$-meson photoproduction at large transverse momentum at
HERA energies via the charm quark excitation in the photon is presented. Based
on perturbative QCD, nonrelativistic quark model and photon structure function
formalism, our calculation demonstrates that the charm content of the photon
may be very important for the $\J$ photoproduction at the large transverse
momentum. It is shown that at HERA energies $\J$ production via the subprocess
$\cg$ dominates over the resolved photon contribution via the gluon-gluon
fusion at $\pt\ge 2$ GeV/c and over the leading order direct photon-gluon
fusion contribution at $\pt\geq 15$ GeV/c.


title: Simple supersymmetric solution to the strong CP problem

abstract:
  It is shown that the minimal supersymmetric left-right model can provide a
natural solution to the strong {\it CP} problem without the need for an axion,
nor any additional symmetries beyond supersymmetry and parity.


title: Test of the Running of $\alpha_s$ in $\tau$ Decays

abstract:
  The $\tau$ decay rate into hadrons of invariant mass smaller than
$\sqrt{s_0}\gg\Lambda_{\rm QCD}$ can be calculated in QCD assuming global
quark--hadron duality. It is shown that this assumption holds for
$s_0>0.7$~GeV$^2$. From measurements of the hadronic mass distribution, the
running coupling constant $\alpha_s(s_0)$ is extracted in the range
0.7~GeV$^2<s_0<m_\tau^2$. At $s_0=m_\tau^2$, the result is
$\alpha_s(m_\tau^2)=0.329\pm 0.030$. The running of $\alpha_s$ is in good
agreement with the QCD prediction.


title: Radiation of Light Fermions in Heavy Fermion Production

abstract:
  Recent analytic calculations on 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 are discussed. The contributions for real and virtual
radiation are displayed separately. The asymptotic behaviour close to threshold
is given in a compact form and an application to the angular distribution of
massive quarks close to threshold is presented.


title:
A Heavy Glueball with Color-Singletness Restriction at Finite
  Temperature

abstract:
  We show that a heavy glueball (much heavier than that studied by others which
is in the range of 1-2 GeV) is generated in a pure gluon plasma when
color-singletness condition is imposed on the partition function at finite
temperature. This confirms Abbas's recent prediction (hep-ph/9504430) of the
existence of a heavy glueball within the framework of the early universe
scenario.


title: Duality of a Supersymmetric Standard Model without R parity

abstract:
  Recently one of the authors proposed a dual theory of a Supersymmetric
Standard Model (SSM), in which it is naturally understood that at least one
quark (the top quark) should be heavy, i.e., almost the same order as the weak
scale, and the supersymmetric Higgs mass parameter $\mu$ can naturally be
expected to be small. Unfortunately, the model cannot possess Yukawa couplings
of lepton sector. In this paper, we examine a dual theory of a Supersymmetric
Standard Model without R parity. In this scenario, we can introduce Yukawa
couplings of lepton sector. In order to induce the enough large Yukawa
couplings of leptons, we must introduce fairly large R parity breaking terms,
which may be observed in the near future.


title: Scheme and Scale Dependence of Charm Production in Neutrino Scattering

abstract:
  We discuss some theoretical uncertainties in the calculation of the cross
section for charm production in charged current deep inelastic neutrino
scattering related to ambiguities in the treatment of terms which are singular
in the limit of a vanishing charm mass. In particular we compare the so-called
variable flavour scheme where these terms are absorbed in the parton
distribution functions containing the charm as an active flavour, with the
so-called fixed flavour scheme with no charm mass subtraction where the charm
appears only in the final state of fixed-order scattering matrix elements.
Using available parametrizations of parton distribution functions we find that
the two schemes lead to largely differing results for separate structure
functions whereas the differences cancel to a large extent in the total cross
section in that kinematical region which has been measured so far.


title: Elastic $\pi\pi$ scattering to two loops

abstract:
  We evaluate analytically the elastic $\pi\pi$ scattering amplitude to two
loops in chiral perturbation theory and give numerical values for the two
$S$--wave scattering lengths and for the phase shift difference
$\delta_0^0-\delta_1^1$.


title: Azimuthal Correlations in Photon-Photon Collisions

abstract:
  Using the general helicity formula for $\gamma^* \gamma^*$ collisions, we are
showing that it should be possible to determine a number of independent
``structure functions'', i.e. linear combinations of elements of the two-photon
helicity tensor, through azimuthal correlations in two-body or quasi two-body
reactions induced by the photon-photon interaction, provided certain
experimental conditions are satisfied. Numerical results of our computations
are presented for some particular processes and dynamic models.


title: A Numerical Estimate of the Small-$k_T$ Region in the BFKL Pomeron

abstract:
  A computer study is performed to estimate the influence of the small-$k_T$
region in the BFKL evolution equation. We consider the small-x region of the
deep inelastic structure function $F_2$ and show that the magnitude of the
small-$k_T$ region depends on $Q^2$ and $x_B$. We suggest that the width of the
$\log k_T^2$-distribution in the final state may serve as an additional
footprint of BFKL dynamics. For diffractive dissociation it is shown that the
contribution of the infrared region is large - even for large $Q^2$. This
contribution becomes smaller only if restrictions on the final state are
imposed.


title: The Problem of Quark and Lepton Masses

abstract:
  Different approaches to the fermion mass problem are reviewed. We illustrate
these approaches by summarizing recent developments in models of quark and
lepton mass matrices. Dynamical calculations of the top quark mass are
discussed, based on (a) infrared quasi-fixed points of the renormalisation
group equations, and (b) the multiple point criticality principle in the pure
Standard Model. We also consider Yukawa unification and mass matrix texture.
Models with approximately conserved gauged chiral flavour charges beyond the
Standard Model are shown to naturally give a fermion mass hierarchy.


title: Nucleon Spin Structure. Sum Rules

abstract:
  Contents:
  1. The sum rules or $\Gamma_{p,n}$.Theoretical status.
  2. Calculations of matrix elements over the polarized nucleon by the QCD sum
rule approach.
  3. Twist-4 corrections to $\Gamma_{p,n}$ from QCD sum rules.
  4. Gerasimov, Drell-Hearn (GDH) sum rules. The estimate of higher twist
corrections to $\Gamma_{p,n}$ using interpolation between $\Gamma_{p,n}$ and
GDH sum rules.
  5. Comparison with experiment.
  6. The calculations of polarized structure functions by the QCD sum rule
method.
  7. Calculation of the chirality violating structure function $h_1(x)$ by QCD
sum rules.
  8. Conclusions.


title:
Strong effects on the hadronic widths of the neutral Higgs Bosons in the
  MSSM

abstract:
  We analyze the correlation of QCD one-loop effects on the partial widths of
the three neutral Higgs bosons of the MSSM decaying into quark-antiquark pairs.
The SUSY-QCD effects turn out to be comparable or even larger than the standard
QCD effects and are slowly decoupling in a wide window of the parameter space.
Our study is aimed at elucidating the possible supersymmetric nature of the
neutral Higgs bosons that might be discovered in the near future at the
Tevatron and/or at the LHC. In particular, we point out the presence of
potentially large SUSY corrections to the various neutral Higgs production
cross-sections.


title: Four-Body Chiral Order Parameters in the Massless Fermion Phase

abstract:
  The fermion four-point functions and condensates as the chiral symmetry order
parameters are calculated analytically in U(1) gauge theory in the massless
phase. It is shown that in leading order of the loop expansion of the effective
action, there is a critical coupling for the nonperturbative parity-invariant
chirality-changing four-fermion functions; this critical coupling however is
the same as that for dynamical mass generation. Therefore there is no breaking
of chiral symmetry through the condensation of four-fermion functions below the
critical coupling for dynamical mass generation for the fermions.


title: Bose-Einstein Correlations for Jets and Heavy Ion Reactions

abstract:
  Bose-Einstein correlations and invariant momentum distributions are analyzed
for longitudinally expanding finite systems, like jets in elementary particle
collisions or systems created in high energy heavy ion reactions. Cross-term
generating hyperbolic mixing angle is introduced for HBT. Temporal or spatial
temperature gradients are shown to contribute to thermal length and time scales
for HBT. Results are illustrated in three figures.


title:
Inclusive Dijet Production at HERA: Direct Photon Cross Sections in
  Next-To-Leading Order QCD

abstract:
  We have calculated inclusive two-jet cross sections in next-to-leading order
QCD for direct photoproduction in low $Q^2$ $ep$ collisions at HERA. Infrared
and collinear singularities in real and virtual contributions are cancelled
with the phase space slicing method. Analytical formulas for the different
contributions giving the dependence on the slicing parameter are presented.
Various one- and two-jet distributions have been computed demonstrating the
flexibility of the method.


title: Some Aspects of Nuclear Deep Inelastic Scattering

abstract:
  Nuclear deep inelastic scattering is considered in the framework of a model
in which the current operator explicitly satisfies Poincare invariance and
current conservation. The results considerably differ from the standard ones at
small values of the Bjorken variable $x$. In particular, it is impossible to
extract the neutron structure functions from the deuteron data at x<0.01 and we
predict that the behavior of the deuteron structure functions at low x and
large momentum transfer considerably differs from the behavior of the nucleon
structure functions at such conditions. We also argue that for heavier nuclei
the effect of the final state interaction is important even in the Bjorken
limit.


title: Higgs Sector Renormalization Group in the MS-bar and OMS Scheme

abstract:
  We discuss different aspects of the Higgs self-interaction in the MS-bar and
the on-mass-shell (OMS) scheme. The running coupling \lambda(\mu) is
investigated in great detail. The three-loop coefficient of the \beta-function
in the OMS scheme is derived, and the three-loop running coupling is
calculated. The breakdown of perturbation theory for large Higgs masses M_H is
analyzed in three physical observables for which two-loop results are known.
Requiring the dependence on the renormalization scale to diminish
order-by-order in \lambda, we find that perturbation theory breaks down for
M_H=O(700 GeV) in Higgs decays. Similarly, M_H must be smaller than O(400 GeV)
for perturbatively calculated cross sections to be trustworthy up to cm
energies of O(2 TeV). If the Higgs sector shall be perturbative up to the GUT
scale, the Higgs must be lighter than O(150 GeV). For the two-loop observables
examined, the apparent convergence of the perturbation series is better in the
OMS scheme than in the MS-bar scheme.


title:
Debye Screening, KMS and Imaginary-Time Formalism of Temporal Axial
  Gauge

abstract:
  We argue that in QCD, the Debye mass requires not only a mathematical
definition but also a physical one and temporal axial gauge could provide for a
physical screening potential for this purpose. Unfortunately, this gauge is
spoiled by problem of energy conservation rather than the well known divergence
due to the double pole in the longitudinal propagator. We also show that KMS
condition is violated in this gauge and is therefore not universally true.


title: Heavy Flavour Physics

abstract:
  The current status of the theory and phenomenology of weak decays of hadrons
containing a heavy quark is reviewed. Exclusive semileptonic and rare decays of
$B$ mesons are discussed, as well as inclusive decay rates, the semileptonic
branching ratio of the $B$ meson, and the lifetimes of $b$-flavoured hadrons.
Determinations of $\alpha_s$ from $\Upsilon$ spectroscopy are briefly
presented.


title: Production of B_c Mesons in Photon-Photon and Hadron-Hadron Collisions

abstract:
  We discuss two-photon and hadronic production of $B_c$ mesons in
nonrelativistic bound state approximation and to lowest order in the coupling
constants $\alpha$ and $\alpha_s$. It is shown that in photon-photon
collisions, heavy quark fragmentation is dominated by recombination of $\bar b$
and $c$ quarks up to the highest accessible transverse momenta. In contrast, in
hadroproduction, which at high energies mainly involves gluon--gluon
collisions, the fragmentation mechanism dominates at transverse momenta $p_T >
m_{B_c}$, providing a simple and satisfactory approximation of the complete
$O(\alpha_s^4)$ results in the high-$p_T$ regime. Contradictions in previous
publications on hadroproduction of $B_c$ mesons are clarified. We also present
predictions for cross sections and differential distributions at present and
future accelerators.


title: Nuclear Effects in Charm Production

abstract:
  I briefly review our understanding of the nuclear target dependence of charm
and charmonium production, in view of charm physics at Elfe.


title: Low-energy QCD

abstract:
  After a brief introduction to chiral perturbation theory, the effective field
theory of the standard model at low energies, two recent applications are
reviewed: elastic pion-pion scattering to two-loop accuracy and the complete
renormalized pion-nucleon Lagrangian to $O(p^3)$ in the chiral expansion.


title: A Heavy Glueball in a Bag Model at Finite Temperature

abstract:
  We obtain a heavy glueball (much heavier than the ones studied by others
which usually are in the range of 1-2 GeV) in a bag model calculation with
exact discrete single particle states of gluons at finite temperature. This
heavy glueball, within the cosmological context, is what Abbas has recently
predicted (hep-ph/9504430).


title: The Higgs resonance shape in gluon fusion: Heavy Higgs effects

abstract:
  We study the influence of two--loop radiative corrections of enhanced
electroweak strength on Higgs production at the LHC. We consider Higgs
production by the gluon fusion mechanism, with the subsequent decay of the
Higgs boson into a pair of Z bosons, and incorporate the resonance shape
corrections up to order $(g^2 \, m_H^2 / m_W^2)^2$. We take into account the
full $g g \rightarrow Z Z$ process and the $q \bar{q} \rightarrow Z Z$
background, as well as the subsequent decay of the Z pair into leptons. We also
discuss the theoretical uncertainty related to the use of the equivalence
theorem in this process.


title:
Particle Spectrum in the Non-Minimal Supersymmetric Standard Model with
  $\tan\beta\simeq m_t/m_b$

abstract:
  We present a detailed discussion of the particle spectrum of the Non-Minimal
Supersymmetric Standard Model (NMSSM), containing two Higgs doublets and a
singlet, in the limit $\tan\beta \simeq m_t/m_b$. This is compared with the
corresponding particle spectrum of the Minimal Supersymmetric Standard Model
(MSSM). In this limit the singlet vacuum expectation value is forced to be
large, of the order of $10$ TeV, and the singlet decouples from the lightest
scalar Higgs boson and the neutralinos. With the exception of the lightest
Higgs boson, the particle spectrum in the model turns out to be heavy. The
radiatively corrected lightest Higgs boson mass is in the neighbourhood of
$\sim 130$ GeV.


title: Radiative corrections to neutrino-majoron couplings

abstract:
  It is claimed that radiative corrections maintain the proportionality between
the neutrino mass and the neutrino-majoron coupling and never give rise to
enhanced decay rates in conventional majoron models. The coupling of a majoron
to neutrinos is calculated at one loop level in various models, including the
singlet majoron model and the Zee model with a majoron. When the respective
corrections to the mass matrix are taken into account the would-be non-diagonal
terms in the neutrino-majoron coupling are rotated away. It is pointed out that
the coincidence between neutrino mass matrices and neutrino-majoron couplings
is not accidental, but is a general consequence of Noether's theorem. Noether's
theorem also implies that the majoron coupling to charged fermions is always
diagonal in the fermion mass basis, and it vanishes completely in the singlet
majoron models.


title: Neutrino propagation in a medium with a magnetic field

abstract:
  We study the properties of neutrinos propagating in an isotropic magnetized
medium in the two physical approximations of degenerate Fermi gas and classical
plasma. The dispersion relation shows that, for peculiar configurations of the
magnetic field, neutrinos can propagate freely as in vacuum, also for very
large density; this result can be very important in the study of supernova
evolution. For mixed neutrinos, the presence of a magnetic field can alter
significatively MSW oscillations, and for particular configurations of the
field the resonance condition no longer occurs. Furthermore, on the contrary to
that happens in non-magnetized media, spatial dispersion arises and neutrino
trajectory can be in principle deviated; however a simple estimate shows that
this deviation is not detectable.


title: Baryon Spectrum and Chiral Dynamics

abstract:
  New results on baryon structure and spectrum developed in collaboration with
Dan Riska [1-4] are reported. The main idea is that beyond the chiral symmetry
spontaneous breaking scale light and strange baryons should be considered as
systems of three constituent quarks with an effective confining interaction and
a chiral interaction that is mediated by the octet of Goldstone bosons
(pseudoscalar mesons) between the constituent quarks.


title: Softly Broken Finite Supersymmetric Grand Unified Theory

abstract:
  In the context of the standard SUSY GUT scenario, we present a detailed
analysis of the softly broken finite supersymmetric grand unified theory. The
model, albeit non-minimal, remains very rigid due to the requirement of
finiteness. It is based on the $SU(5)$ gauge group and is UV finite to all
orders of perturbation theory. It contains three generations of the matter
fields together with four pairs of Higgses. The requirement of UV finiteness
fixes all the Yukawa couplings at the GUT scale. Imposing the condition of
universality on the soft couplings at the Planck scale and then extending the
condition of finiteness to them, one gets a completely finite unified theory
above $M_{GUT}.$ This makes the fine-tuning procedure more meaningful and leads
to the usual Minimal Supersymmetric Standard Model below $M_{GUT}$. All the
masses of the ordinary particles including Higgses are obtained due to the
Higgs mechanism at the electro-weak scale. The hierarchy of quark and lepton
masses is related to that of v.e.v.'s of the Higgs fields and is governed by
the Higgs mixing matrix in the generation space. Superpartners develop their
masses according to the RG equations starting from the soft terms at the Planck
scale. The suggestion of complete finiteness and maximal simplicity of the
unified theory leads to the connection between the initial values of soft SUSY
breaking parameters, namely $m_0^2=1/3m_{1/2}^2,\ A_t=A_b=A_\tau=-m_{1/2}, \
B=-m_{1/2}$, so that the number of free parameters is less than that of the
MSSM.


title: Longitudinal quark polarization in transversely polarized nucleons

abstract:
  Accounting for transverse momenta of the quarks, a longitudinal quark spin
asymmetry exists in a transversely polarized nucleon target. The relevant
leading quark distribution $g_{1T}(x,k_T^2)$ can be measured in the
semi-inclusive deep-inelastic scattering. The average $k_T^2$ weighted
distribution function $g^{(1)}_{1T}$ can be obtained directly from the
inclusive measurement of $g_2$.


title:
Selectron Pair Production in e+e- Colliders and the Supergravity
  Spectrum

abstract:
  Selectrons may be produced in pairs at LEPII if their mass is less than about
100 GeV. Preferably, they decay into the lightest neutralino plus an electron.
In a scenario where selectrons are observed at LEPII, we show that: (i) in a
first stage where experimental errors are large, the measurement of the total
cross section of selectron pair production, the selectron mass, and the
lightest neutralino mass, allow us to validate or rule out the Minimal
Supergravity Model in its simplest form, and that (ii) in a second stage where
precision measurements are available, the value of $\tan\beta$ can be
determined together with the rest of the parameters that specify the Minimal
Supergravity Model and, with them, the entire supersymmetric spectrum can be
calculated. We include experimental constraints from sparticle searches,
$Z$--pole physics, stability of the lightest supersymmetric particle (LSP) and
the decay $b\rightarrow s\gamma$. In these scenarios, small values of
$\tan\beta$ and negative values of $\mu$ are preferred, and the lightest Higgs
mass satisfies $m_h<110$ GeV, which makes it likely to be detected at LEPII.


title:
Glueball Spectroscopy in a Relativistic Many-Body Approach to Hadron
  Structure

abstract:
  A comprehensive, relativistic many-body approach to hadron structure is
advanced based on the Coulomb gauge QCD Hamiltonian. Our method incorporates
standard many-body techniques which render the approximations amenable to
systematic improvement. Using BCS variational methods, dynamic chiral symmetry
breaking naturally emerges and both quarks and gluons acquire constituent
masses. Gluonia are studied both in the valence and in the collective, random
phase approximations. Using representative values for the strong coupling
constant and string tension, calculated quenched glueball masses are found to
be in remarkable agreement with lattice gauge theory.


title:
Second quantization approach to composite hadron interactions in quark
  models

abstract:
  Starting from the Fock space representation of hadron bound states in a quark
model, a change of representation is implemented by a unitary transformation
such that the composite hadrons are redescribed by elementary-particle field
operators. Application of the unitary transformation to the microscopic quark
Hamiltonian gives rise to effective hadron-hadron, hadron-quark, and
quark-quark Hamiltonians. An effective baryon Hamiltonian is derived using a
simple quark model. The baryon Hamiltonian is free of the post-prior
discrepancy which usually plagues composite-particle effective interactions.


title: Nucleon Spin and the Mixing of Axial Vector Mesons

abstract:
  It is shown that the QCD anomaly may lead to an abnormal mixing behavior of
the axial vector mesons similar to the pseudoscalar mesons. These mixing
effects, involving a gluonic axial vector state, generate a non-vanishing
strange quark component in the nucleon. They reduce the matrix element of the
singlet axial vector in comparison to the value obtained in a naive quark
model. The results are in agreement with the data obtained in the polarized
lepton-nucleon scattering experiments.


title: The Pomeron in Elastic and Deep Inelastic Scattering

abstract:
  We discuss some properties of the Pomeron in high energy elastic
hadron-hadron and deep inelastic lepton-hadron scattering. A number of issues
concerning the nature and the origin of the Pomeron are briefly recalled here.
The novelty in this paper resides essentially in its presentation; we strive at
discussing all these various issues in the following unifying perspective : it
is our contention that the Pomeron is one and the same in all reactions.
Various examples will be provided illustrating why we do not believe that one
should invoke additional tools to describe the data. For pedagogical
convenience, we list below the topics to be covered in the following.
  -- 1. Introduction. How many Pomerons?
  -- 2. The Pomeron in the $S$-matrix theory
  -- 3. The Pomeron in QCD
  -- 4. The Pomeron in deep inelastic scattering
  -- 5. The Pomeron structure
  -- 6. (Temporary?) Conclusions


title: A new scenario for string unification

abstract:
  We present a new scenario for gauge coupling unification in flipped SU(5)
string models, which identifies the $M_{32}$ scale of SU(3) and SU(2)
unification with the empirical $M_{\rm LEP}\sim10^{15-16}$~GeV scale, and the
$M_{51}$ scale of SU(5) and U(1) unification with the theoretical $M_{\rm
string}\sim5\times10^{17}$~GeV string unification scale. The vacuum shift
necessary for the cancellation of the anomalous $\rm U_A(1)$ and an SU(4)
hidden sector with fractionally-charged particles, play a crucial role in the
dynamical determination of all intermediate mass scales in this scenario.


title: Surprising Results from Cosmic Rays

abstract:
  A number of seemingly {\it exotic} phenomena seen in the highest cosmic-ray
experiments are briefly discussed. We argue that they indicate existence of
non-statistical fluctuations and strong correlations in the fragmentation
region of multiparticle production processes unaccessible to the present
accelerators.


title:
Recent Neutrino Experiments and Their Consistency In An Extended Harvard
  Model

abstract:
  We demonstrate that the solar and atmospheric neutrino data as well as the
recent result of the LSND experiment cannot be satisfied simultaneously with
three light neutrinos if we consider the mass degeneracy for two neutrinos in
the context of an extended Harvard Model based on the gauge group
$SU(2)_{qL}\times {SU(2)}_{lL}\times {U(1)}_Y$ with $S_3\times Z_4$ discrete
symmetry. Assuming two different representation contents under $S_3\times Z_4$
symmetry for pairwise neutrinos and the lone neutrino the present model admits
neutrino masses of the order of 2.8 eV and can fit either solar and atmospheric
neutrino data or the LSND and solar neutrino data.


title: Signatures of Supersymmetry at B-Factories

abstract:
  We discuss CP asymmetries in $B^0$-meson decays and \BsBs mixing within the
framework of the supersymmetric standard model (SSM). It is shown that \BdBd
and \KK mixings could receive sizable new contributions through box diagrams
mediated by the charginos and charged Higgs bosons. This implies that the
CP-violating phase of the Cabibbo-Kobayashi-Maskawa matrix may have a value
which is different from the one predicted by the standard model (SM). The value
of the CP-violating phase affects the amounts of the CP asymmetries and \BsBs
mixing. We examine predictions for these quantities in both the SSM and the SM,
exploring the difference between the two models.


title: Heavy Quark Vacuum Polarisation to Three Loops

abstract:
  The real and imaginary part of the vacuum polarisation function $\Pi(q^2)$
induced by a massive quark is calculated in perturbative QCD up to order
$\alpha_s^2$. The method is described and the results are presented. This
extends the calculation by K\"all\'en and Sabry from two to three loops.


title:
Quantum Restoration of the U(1)_Y Symmetry in Dynamically Broken
  SUSY-GUT's

abstract:
  We propose a supersymmetric hypercolor SU(3)_H gauge theory interacting
strongly at the grand unification scale, in which the hyperquark condensation
breaks SU(5)_GUT down to SU(3)_C x SU(2)_L without unbroken U(1)_Y at the
classical level. However, we show that the broken U(1)_Y symmetry is restored
by quantum mechanical effects and hence there remains the standard-model gauge
symmetry at the electroweak scale. The dynamics of the strong interactions also
produces naturally a pair of massless Higgs doublets. In addition to these
Higgs doublets, we have a pair of massless singlets which contributes to the
renormalization-group equations of gauge coupling constants and hence affects
the GUT unification. We discuss a simple solution to this problem.


title: Glueball plus pion production in hadron collisions

abstract:
  Using a non--relativistic gluon bound--state model for glueballs (G), we
compute the subprocess $q\,\bar q\, \to\, G\,\pi$, and we therefrom derive the
yield of the overall reaction $p\,\bar p\, \to\, G\,\pi X$, assuming the
glueball and the pion to be emitted with their transverse momenta large,
opposite and approximately equal. Numerical results are presented in the form
of $p_T$ spectra for various glueball candidates and their possible quantum
states, assuming those particles to be produced, in the type of reactions here
considered, at high--energy $p\,\bar p$ colliders such as the CERN Sp\=pS.


title: J/psi production via fragmentation at HERA

abstract:
  We compute the contributions to large-$p_T$ $J/\psi$ production at HERA
coming from fragmentation of gluons and charm quarks. We find that the charm
quark fragmentation contribution dominates over the direct production of
$J/\psi$ via photon-gluon fusion at large-$p_T$, while the gluon fragmentation
is negligibly small over the whole range of $p_T$. An experimental study of
$p_T$ distributions of $J/\psi$ at HERA will provide a direct probe of the
charm quark fragmentation functions.


title:
HECTOR 1.00 - A program for the calculation of QED, QCD and electroweak
  corrections to ep and lN deep inelastic neutral and charged current
  scattering

abstract:
  A description of the Fortran program HECTOR for a variety of semi-analytical
calculations of radiative QED, QCD, and electroweak corrections to the
double-differential cross sections of NC and CC deep inelastic charged lepton
proton (or lepton deuteron) scattering is presented. HECTOR originates from the
substantially improved and extended earlier programs HELIOS and TERAD91. It is
mainly intended for applications at HERA or LEPxLHC, but may be used also for
muon scattering in fixed target experiments. The QED corrections may be
calculated in different sets of variables: leptonic, hadronic, mixed,
Jaquet-Blondel, double angle etc. Besides the leading logarithmic approximation
up to order O(alpha^2), exact order O(alpha) corrections and inclusive soft
photon exponentiation are taken into account. The photoproduction region is
also covered.


title: Renormalons and perturbative fixed points

abstract:
  The connection between renormalons and power corrections is investigated for
the typical infrared renormalon integral assuming the effective coupling
constant has an infrared fixed point of an entirely perturbative origin. It is
shown the full answer differs from the Borel sum by a power correction.


title:
Neutral Kaon decay without symmetry violation: A nonstandard theoretical
  speculation

abstract:
  It is shown that if antiparticles are realized in quantum field theory by
negative frequency states, which nevertheless have positive energy density, the
resulting theory provides a qualitative explanation for the experiments on the
neutral K mesons, without assumming any symmetry violation.


title: Charged Majoron Emission in Neutrinoless Double Beta Decay

abstract:
  We examine in detail the predictions of the charged majoron model, introduced
recently by Burgess and Cline, for 0+ --> 0+ double beta decay transitions. The
relevant nuclear matrix elements are evaluated, within the quasiparticle random
phase approximation, for 76Ge, 82Se, 100Mo, 128Te and 150Nd nuclei. The
calculated transition rates turn out to be much smaller than the experimental
upper limits on possible majoron emission, except in a small region of the
model's parameter space.


title: Particle Physics: Themes and Challenges

abstract: Opening Lecture at the Second Rencontres du Vietnam, October 21-28, 1995.


title: Direct Tests of Dynamical Electroweak Symmetry Breaking

abstract:
  We review the connection between $m_t$ and the $Zb\bar b$ vertex in ETC
models and discuss the resulting experimental constraint on models with
weak-singlet ETC bosons. We mention several recent efforts to bring ETC models
into agreement with this constraint, and explore the most promising one
(non-commuting ETC) in detail.


title: Leading Charm Production in the Interacting Gluon Model

abstract:
  We discuss leading charm production in connection with energy deposition in
the central rapidity region. Special attention is given to the correlation
between production in central and fragmentation regions. If the fraction of the
reaction energy released in the central region increases the asymmetry in the
$x_F$ distributions of charmed mesons will become smaller. We illustrate this
quantitatively with simple calculations performed using the Interacting Gluon
Model. Leading beauty production is also considered.


title: K0 form factor and charge radius in a covariant Salpeter model

abstract:
  The electromagnetic form factor for the $K^0$ is calculated in a covariant
formulation of the Salpeter equation for $q\bar q$ - bound states, which has
been presented recently for the mass spectrum, decay properties and form
factors of the light pseudoscalar and vector mesons. The $K^0$ charge radius
dependence on the difference between strange and down constituent quark mass is
discussed.


title: From Coloured Quarks to Quarkonia, Glueballs and Hybrids

abstract:
  Lectures at VII Jorge Andre Swieca Summer School in Nuclear Physics; Brasil;
Jan 22 - Feb 4 1995. To be published by Plenum Press (C.A.Amaral Nunes ed.)


title: Initial bound state studies in light-front QCD

abstract:
  We present the first numerical QCD bound state calculation based on a
renormalization group-improved light-front Hamiltonian formalism. The QCD
Hamiltonian is determined to second order in the coupling, and it includes
two-body confining interactions. We make a momentum expansion, obtaining an
equal-time-like Schrodinger equation. This is solved for quark-antiquark
constituent states, and we obtain a set of self-consistent parameters by
fitting B meson spectra.


title:
2-Loop Supersymmetric Renormalization Group Equations Including R-parity
  Violation and Aspects of Unification

abstract:
  We present the complete 2-loop renormalization group equations of the
supersymmetric standard model. We thus explicitly include the full set of $R
$-parity violating couplings, including $\kappa_iL_iH_2$. We use these
equations to do a first study of $(a)$ gauge coupling unification, $(b)$
bottom-tau unification, $(c)$ the fixpoint structure of the top quark Yukawa
coupling, and (d) two-loop bounds from perturbative unification. We find
significant shifts which can be larger than the effect from the top quark
Yukawa coupling. The value of $\alpha_3(M_Z)$ can change by $\pm5\%$. The
$\tan\beta$ region for bottom-tau unification and for the top quark IR quasi
fixed point structure is significantly increased. For heavy scalar fermion
masses ${\cal{O}}(1\tev)$ the limits on the $\Delta L\not=0$ operators from
perturbative unification are competitive with the indirect laboratory bounds.
The two-loop correction to the bound on the $\Delta B\not=0$ opertor is $+15\%
$.


title: Constraining $\alpha_s(M_Z)$ from the Hidden Sector

abstract:
  By including the effects of superstring thresholds, we reconsider minimal
string unification together with the requirement of producing a
supersymmetry-breaking gluino condensate in the hidden sector. This gives, for
examples of phenomenologically-viable $Z_8'$ and other related orbifolds, the
constraint that $0.1215 \leq \alpha_s(M_Z) \leq 0.1270$. In such models, a
hidden photino can be a source of cosmological dark matter detectable by
gravitational microlensing.


title: Large neutrino mixing angles in unified theories

abstract:
  Typically in unified theories the neutrino mixing angles, like the
Cabibbo-Kobayashi-Maskawa (CKM) angles of the quarks, are related to the small
mass ratios between fermions of different generations and are therefore quite
small. A new approach for explaining the intergenerational mass hierarchies is
proposed here which, while giving small CKM angles, naturally leads to neutrino
angles of order unity. Such large mixing angles may be required for a
resolution of the atmospheric neutrino anomaly and may also be relevant for the
solar neutrino puzzle. The mechanism presented here provides a framework in
which novel approaches to the fermion mass question can arise. In particular,
within this framework a variant of the texture idea allows highly predictive
models to be constructed, an illustrative example of which is given. It is
shown how the neutrino mixing angles may be completely determined in such
schemes.


title:
LEP- and low energy-bounds on R-parity-violating supersymmetric Yukawa
  couplings

abstract:
  Electroweak precision data at LEP are used to place bounds on some
$\lambda'$-type ($L$-violating) and $\lambda''$-type ($B$-violating) $R$-parity
violating supersymmetric Yukawa couplings. We consider one-loop corrections
(triangles and self-energies) induced by these couplings to the $Z$-partial
widths. The couplings involving the top quark induce stronger loop effects and
hence are more strongly constrained than others. On the other hand, information
on $D$- and $\tau$-decays are used to constrain some of the $\lambda'$-type
couplings which are complementary to the ones constrained from LEP. Among the
bounds we have derived, many are new from a phenomenological view-point.


title: Dijet Production at HERA in Next-to-Leading Order

abstract:
  Two-jet cross sections in deep inelastic scattering at HERA are calculated in
next-to-leading order. The QCD corrections are implemented in a new
$ep\rightarrow n$ jets event generator, MEPJET, which allows to analyze
arbitrary jet definition schemes and general cuts in terms of parton 4-momenta.
First results are presented for the JADE, the cone and the $k_T$ schemes. For
the $W$-scheme, disagreement with previous results and large radiative
corrections and recombination scheme dependencies are traced to a common
origin.


title: QCD Corrections to W Boson plus Heavy Quark Production at the Tevatron

abstract:
  The next-to-leading order QCD corrections to the production of a $W$-boson in
association with a jet containing a heavy quark are presented. The calculation
is fully differential in the final state particle momenta and includes the mass
of the heavy quark. We study for the case of the Tevatron the sensitivity of
the cross section to the strange quark distribution function, the dependence of
the cross section on the heavy quark mass, the transverse momentum distribution
of the jet containing the heavy quark, and the momentum distribution of the
heavy quark in the jet.


title: QCD in the axial gauge

abstract:
  We review a recent attempt to deal with non-perturbative features of QCD by
analytical means, using a manifestly gauge invariant, canonical approach.


title:
Degenerate Dirac Neutrinos In An ${SU(2)}_L\times {U(1)}_Y$ Model With
  $S_3\times Z_3\times Z_4$ Discrete Symmetry

abstract:
  We demonstrate that almost degenerate Dirac neutrinos of mass of few eV and
transition magnetic moment of the order of ${10}^{-11}$ $\mu_B$ can be obtained
in an ${SU(2)}_L\times {U(1)}_Y$ model with $S_3\times Z_3\times Z_4$ discrete
symmetry and appropriate Higgs fields. Transition magnetic moment of the Dirac
neutrino arises from to the contribution of leptons and charged Higgs fields at
the one loop level.


title: Spin effects in hard exclusive reactions

abstract:
  The present status of applications of perturbative QCD to large momentum
transfer exclusive reactions is discussed. It is argued that in the region of
momentum transfer accessible to present day experiments soft contributions
dominate the exclusive processes.


title: CP Investigations in the Higgs Sector

abstract:
  In a more general electroweak theory, there could be Higgs particles that are
odd under $CP$. When such particles decay via vector bosons to two
fermion-antifermion pairs, the momenta of those will be correlated in a way
which is determined by the $CP$ of the particle. Similarly, in the Bjorken
process correlations among momenta of the initial electron and final-state
fermions are sensitive to the $CP$ quantum number. Monte Carlo data on the
expected efficiency demonstrate that it should be possible to verify the scalar
character of an intermediate-mass Standard Model Higgs boson after three years
of data taking at a future linear collider. This is most likely not possible at
LEP2. Signals of possible presence of $CP$ violation in the Higgs sector are
briefly discussed.


title:
Phenomenology of the $1/m_Q$ Expansion in Inclusive $B$ and $D$ Meson
  Decays

abstract:
  We apply a recent theoretical analysis of hadronic observables in inclusive
semileptonic heavy hadron decays to the phenomenology of $B$ and $D$ mesons.
Correlated bounds on the nonperturbative parameters $\bar\Lambda$ and
$\lambda_1$ are derived by considering data from $B$ decays and, independently,
data from $D$ decays. The two sets of bounds are found to be consistent with
each other. The data from $B$ decays are then are used to extract a lower limit
on the CKM matrix element $|V_{cb}|$. We address the issue of the convergence
of the perturbative expansions used in the analysis, and compare our bounds on
$\bar\Lambda$ and $\lambda_1$ to lattice and QCD sum rule results. Finally, we
argue that a comparison of the analyses of $D$ and $D_s$ decays provides
evidence for the applicability of parton-hadron duality in the semileptonic
decay of charmed hadrons.


title: An effective model for charmed meson semileptonic decays

abstract:
  We analyze charm meson semileptonic decays using the measured ratios
$\Gamma_L/\Gamma_T$ and $\Gamma_{+}/\Gamma_{-}$ from $D\to {\bar K}^{*}$ and
the branching ratios for $D \to {\bar K}^{*}$ and $D \to {\bar K}$. First we
introduce the light vector mesons in a model which combines the heavy quark
effective Lagrangian and the chiral perturbation approach. We propose a method
which predicts the behavior of the form factors. Using the available
experimental data we determine the values of some model parameters and
reproduce the observed branching ratios for $D_{s} \to \Phi$, $D_{s} \to (\eta
+ \eta^{\prime})$ and $D \to \pi$. We make predictions for the yet unmeasured
branching ratios and polarization observables.


title: Four-Dimensional Superstring Models

abstract:
  These lectures from the 1995 Trieste Summer School in High Energy Physics and
Cosmology give an elementary introduction to perturbative superstring theory,
superstring phenomenology, and the fermionic construction of perturbative
string models.These lectures assume no prior knowledge of string theory.


title: Critical Angle in the Parton Cascade

abstract:
  The angular correlation function of partons in a jet, as derived from
perturbative QCD, is nonanalytic at a critical angle which separates a
multiparticle regime with scaling properties from a regime with few particles
near the hadronisation scale. Some phenomenological consequences are discussed.


title:
Can $\Omega^- \to \Xi^- \gamma$ be sensitive to new physics beyond the
  Standard Model ?

abstract:
  We investigate the impact of new physics beyond the Standard Model to the $s
\rightarrow d \gamma$ process, which is responsible for the short-distance
contribution to the radiative decay $\Otogamma$. We study three representative
extensions of the Standard Model, namely a one-family technicolor model, a two
Higgs doublet model and a model containing scalar leptoquarks. When constraints
arising from the observed $b \to s \gamma$ transition and the upper limit on
$D^0 - \bar{D}^0$ mixing are taken into account, we find no significant
contributions of new physics to the $s \to d \gamma$ process.


title: Top pair production with an extra gluon at the Tevatron

abstract:
  We calculate top pair production and decay at the Tevatron $p\bar p$
collider, with the emission of an extra gluon, and study the corresponding
$W+5$\,jet top signals including full spin correlations in the $W \to \ell\nu$
leptonic and $W\to jj$ hadronic decays. We study the feasibility of
reconstructing $W+5$\,jet top events with a single $b$-tag, including realistic
energy resolution. Our suggested basic procedure based on kinematic fitting
achieves about 74\% reconstruction efficiency, with 74\% of the reconstructed
events correctly classified (purity); this improves to 82\% efficiency with
77\% purity in double-$b$-tagged events. We suggest possible refinements, based
on virtuality criteria, that give higher purity at the cost of lower
reconstruction efficiency.


title: Inflation From Symmetry Breaking Below the Planck Scale

abstract:
  We investigate general scalar field potentials \hbox{$V\left(\phi\right)$}
for inflationary cosmology arising from spontaneous symmetry breaking. We find
that potentials which are dominated by terms of order $\phi^m$ with \hbox{$m >
2$} can satisfy observational constraints at an arbitrary symmetry breaking
scale. Of particular interest, the spectral index of density fluctuations is
shown to be independent of the specific form of the potential, depending only
on the order $m$ of the lowest non-vanishing derivative of $V(\phi)$ near its
maximum. The results of a model with a broken ${\rm SO(3)}$ symmetry illustrate
these features.


title: Mass sum rules for singly and doubly heavy-flavored hadrons

abstract:
  Regularities in the hadron interaction energies are used to obtain formulas
relating the masses of ground-state hadrons, most of which contain heavy
quarks. Inputs are the constituent quark model, the Feynman-Hellmann theorem,
and the structure of the colormagnetic interaction of QCD. Some of the formulas
can also be obtained from heavy quark effective theory or from
diquark-antiquark supersymmetry. It is argued that the sum rules are more
general than the model from which they are obtained. Where data exist, the
formulas agree quite well with experiment, but most of the sum rules proposed
provide predictions of heavy baryon masses that will be useful for future
measurements.


title: A Study of Some Methods for Measuring CKM CP Violating Phases

abstract:
  We study the influence of penguin (especially, electroweak penguin) effects
on some methods of measuring the angles $\alpha$, $\beta$, and $\gamma$ in the
CKM unitarity triangle. We use next-to-leading order effective Hamiltonian, and
present numerical estimates based on the factorization approximation. We find
that some techniques suggested in the literature, especially for $\alpha$
determination, are not workable in light of the electroweak penguin effects.
Nevertheless, there are methods that would work for each angle determination.
For angle $\beta$ we consider $B \rightarrow D^{+} D^{-}$ mode and estimate the
penguin contamination. For angle $\gamma$ we consider a method based on SU(3)
symmetry and carefully consider SU(3) breaking effects. We point out regions in
the parameter space where this method could be used reliably.


title: Heavy Fermion Screening Effects and Gauge Invariance

abstract:
  We show that the naively expected large virtual heavy fermion effects in low
energy processes may be screened if the process under consideration contains
external gauge bosons constrained by gauge invariance. We illustrate this by a
typical example of the process $\gamma\gamma\to b \bar{b}$. Phenomenological
implications are also briefly indicated.


title:
Search for flavor lepton number violation in slepton decays at LEP2 and
  NLC

abstract:
  We show that in supersymmetric models with explicit flavor lepton number
violation due to soft supersymmetry breaking terms there must be flavor lepton
number violation in slepton decays. We propose to look for flavor lepton number
violation in righthanded selectron and smuon decays. For selectron and smuon
lighter than 80 Gev flavor lepton number violation in slepton decays could be
discovered at LEP2 provided the mixing betwen selectron and smuon is not small.
We also estimate NLC discovery potential of the lepton flavor number violation
in slepton decays.


title: Weak $K$--Amplitudes in the Chiral and $1/N_c$--Expansions

abstract:
  It is shown that there exist symmetry constraints for non--leptonic weak
amplitudes which emerge when the $1/N_c$--expansion restricted to the leading
and next--to--leading approximations only is systematically combined with
$\chi$PT limited to the lowest non--trivial order. We discuss these constraints
for the couplings $\mbox{\bf g}_8$ and $\mbox{\bf g}_{27}$ of $\Delta S=1$
transitions and the $\mbox{\bf B}_{K}$--parameter of $K^0-{\bar K}^0$ mixing.


title: R-Parity Violation at LEP2 : Virtual Effects

abstract:
  We investigate the ability of LEP2 to detect possible $R$-parity violation,
especially for the case where direct production cross-sections are too small
for all superparticles. We demonstrate that for coupling strengths allowed by
present experiments, sfermion-exchange diagrams can contribute significantly to
the $e^+ e^- \rightarrow f \bar{f} $ process. This would be a useful tool in
further constraining the parameter space. Similar arguments hold for
leptoquarks and dileptons as well.


title: The hidden Higgs model at LEP2

abstract:
  The influence of massless scalar singlets on the Higgs signal at LEP2 is
discussed. It is shown that for strong interactions between the Higgs boson and
the singlet fields, detection of the Higgs signal can become impossible.


title: Top Quark Pair Production: Sensitivity to New Physics

abstract:
  The production cross--section and distributions of the top quark are
sensitive to new physics, e.g., the $t\overline{t}$ system can be a probe of
new resonances or gauge bosons that are strongly coupled to the top quark, in
analogy to Drell--Yan production. The existence of such new physics is expected
in dynamical electroweak symmetry breaking schemes, and associated with the
large mass of the top quark. The total top production cross--section can be
more than doubled, and distributions significantly distorted with a chosen
scale of new physics of $\sim 1 $ TeV in the vector color singlet or octet
$s$--channel. New resonance physics is most readily discernible in the
high--$p_T$ distributions of the single top quark, of the $W$ boson and the
mass distribution of the $t\bar{t}$ pair.


title:
The Case of $\alpha_s$: $Z$ versus Low Energies, or How Nature Prompts
  us of New Physics

abstract:
  The values of $\alpha_s$ determined from low- and high-energy measurements
are in irreconcilable contradiction with each other. The current status of the
problem is critically reviewed. Consequences of the $\alpha_s$ contradiction,
in conjunction with other anomalies detected at the $Z$ peak, are discussed.
The write-up is updated in accordance with experimental numbers reported at
summer conferences.


title: Inflation in S-Dual Superstring Models

abstract:
  We study inflationary potentials in the framework of superstring theories.
Successful inflation may occur due to chiral fields, but only after the dilaton
and moduli are stabilized. This is achieved by demanding an S-duality invariant
potential. Then, it is possible to have inflation at any scale and even to have
more than one stages of inflation. This occurs for a limited class of scalar
potentials, where certain conditions are obeyed. Density fluctuations of
$10^{-5}$ require the inflationary potential to be at a scale of $V^{1/4}\simeq
5 \times 10^{15}$ GeV.


title: Scalar susceptibility in QCD and the multiflavor Schwinger model

abstract:
  We evaluate the leading infrared behavior of the scalar susceptibility in QCD
and in the multiflavor Schwinger model for small non-zero quark mass $m$ and/or
small nonzero temperature as well as the scalar susceptibility for the finite
volume QCD partition function. In QCD, it is determined by one-loop chiral
perturbation theory, with the result that the leading infrared singularity
behaves as $\sim \log m$ at zero temperature and as $\sim T/\sqrt m$ at finite
temperature. In the Schwinger model with several flavors we use exact results
for the scalar correlation function. We find that the Schwinger model has a
phase transition at $T=0$ with critical exponents that satisfy the standard
scaling relations. The singular behavior of this model depends on the number of
flavors with a scalar susceptibility that behaves as $\sim m^{-2/(N_f+1)}$. At
finite volume $V$ we show that the scalar susceptibility is proportional to
$1/m^2V$. Recent lattice calculations of this quantity by Karsch and Laermann
are discussed.


title: Top Quark Production Dynamics

abstract:
  I review standard top quark production at the Fermilab Tevatron. The current
theoretical understanding of the total cross section and many partial
differential cross sections is presented. Studies on the effects of extra gluon
radiation on the top quark mass determination are reviewed. The possibility of
new mechanisms for $t\bar{t}$ production are also discussed.


title: Renormalization group evolution of R-parity-violating Yukawa couplings

abstract:
  We study the evolution of $R$-parity-violating (RPV) couplings in the minimum
supersymmetric standard model, between the electroweak and grand unification
scales, assuming a family hierarchy for these coupling strengths. Particular
attention is given to solutions where both the $R$-conserving and $R$-violating
top quark Yukawa couplings simultaneously approach infrared fixed points; these
we analyse both algebraically and with numerical solutions of the evolution
equations at one-loop level. We identify constraints on these couplings at the
GUT scale, arising from lower limits on the top quark mass. We show that fixed
points offer a new source of bounds on RPV couplings at the electroweak scale.
We derive evolution equations for the CKM matrix, and show that RPV couplings
affect the scaling of the unitarity triangle. The fixed-point behaviour is
compatible with all present experimental constraints. However, fixed-point
values of RPV top-quark couplings would require the corresponding sleptons or
squarks to have mass $\agt m_t$ to suppress strong new top decays to
sparticles.


title: A scale-dependent cosmology for the inhomogeneous Universe

abstract:
  A scale-dependent cosmology is proposed 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 are discussed.


title: The Solar Neutrino Puzzle: Update

abstract:
  In this talk I will summarize the latest experimental results from the four
solar neutrino experiments and discuss what this means for the flux of $^7Be$
and $^8B$ neutrinos. The implications for the solar models including the new
versions with helium and heavy element diffusion will also be addressed. The
exciting and important calibration results of the Gallex collaboration will be
presented as well as the outlook for the next generation of solar neutrino
experiments.


title: Physics at an $e^-e^-$ Facility

abstract:
  We review some of the reactions which can be studied in the $e^-e^-$ mode of
a linear collider and may reveal aspects of physics beyond the realm of the
standard model. The complementarity to $e^+e^-$ scattering is stressed.


title: On Bubble Growth and Droplet Decay in Cosmological Phase Transitions

abstract:
  We study spherically symmetric bubble growth and droplet decay in first order
cosmological phase transitions, using a numerical code including both the
complete hydrodynamics of the problem and a phenomenological model for the
microscopic entropy producing mechanism at the phase transition surface. The
small-scale effects of finite wall width and surface tension are thus
consistently incorporated. We verify the existence of the different
hydrodynamical growth modes proposed recently and investigate the problem of a
decaying quark droplet in the QCD phase transition. We find that the decaying
droplet leaves behind no rarefaction wave, so that any baryon number
inhomogeneity generated previously should survive the decay.


title: Renormalons and fixed points

abstract:
  The connection between renormalons and power corrections is investigated for
the typical infrared renormalon integral assuming the effective coupling
constant has an infrared fixed point of an entirely perturbative origin. It is
shown that even then the full answer differs from the Borel sum by a power
correction. A comparaison with the analogue results when the fixed point is
generated by the explicit addition of non perturbative power suppressed terms
is given.


title:
On the universality of the $x$ and $A$ dependence of the EMC effect and
  its relation to parton distributions in nuclei

abstract:
  It is shown that the latest results from the NMC (CERN) and E665 (Fermilab)
groups on $F_2^A(x)/F_2^D(x)$ obtained in the shadowing region bring new
evidence of the universal $A$ dependence of distortions made in a free-nucleon
structure function by a nuclear medium.
  The observed universality implies that one can consider separately hard
($A\leq$ 4) and soft ($A>$ 4) parton distribution distortions. Soft
distortions, which result in differencies between the deep-inelastic scattering
cross-sections for nuclei with masses $A_1$, $A_2 \geq$ 4, can be explained as
a consequence of the nuclear density variation, independent of $x$ in the range
0.001 $\leq x \leq$ 0.7.
  It is found that nuclear shadowing begins at $x_{\rm I}$ = 0.0615 $\pm$
0.0024, independent of $A$, which is consistent with models that allow for
three-parton recombination processes.


title: Physics of Heavy Quarks

abstract:
  Selected problems in heavy quark physics are discussed. The wealth of
research problems in this field of physics is stressed.


title: Resonance $f_0(1500)$: Is it a scalar glueball ?

abstract:
  The ratios of partial widths for the decay of a glueball into two
pseudoscalar mesons are calculated under the assumption that the production of
light quark pairs ($u\bar u,d\bar d,s\bar s$) in soft gluon-\-induced reactions
goes on within universal symmetry breaking. Parameter of the violation of
flavour symmetry is fixed by the central hadron production data in high energy
hadron collisions and/or by the ratios of radiative decay amplitudes $J/\Psi
\to \gamma\eta/\gamma\eta'$ and $J/\Psi \to \gamma \phi \phi/\gamma \omega
\omega$. The ratios of coupling constants $glueball\to\pi\pi,K\bar K,
\eta\eta,\eta\eta'$ which are calculated with this parameter coincide
reasonably with those of $f_0(1500)$, supporting an idea about glueball nature
of $f_0(1500)$.


title:
Instabilities, Point Attractors and Limit Cycles in a Inflationary
  Universe

abstract:
  We study the stability of a scalar inflaton field and analyze its point
attractors in the phase space. We show that the value of the inflaton field in
the vacuum is a bifurcation parameter and prove the possible existence of a
limit cycle by using analytical and numerical arguments.


title: Universality and Scaling in Perturbative QCD at Small x

abstract:
  We present a pedagogical review of the universal scaling properties displayed
by the structure function F_2 at small x and large Q^2 as measured at HERA. We
first describe the derivation of the double asymptotic scaling of F_2 from the
leading-order Altarelli-Parisi equations of perturbative QCD. Universal
next-to-leading order corrections to scaling are also derived. We explain why
the universal scaling behaviour is spoiled when the initial distributions rise
too steeply by considering the nonsinglet distribution F_2^p-F_2^n as an
explicit example. We then examine the stability of double scaling to the
inclusion of higher order singularities, explaining how the perturbative
expansion at small x can be reorganized in such a way that each order is given
by the sum of a convergent series of contributions which are of arbitrarily
high order in the coupling. The wave-like nature of perturbative evolution is
then shown to persist throughout almost all the small x region, giving rise
asymptotically to double scaling for a wide class of boundary conditions.


title: A Review of the Soft Pomeron

abstract:
  Soft pomeron fits reproduce all zero-Q2 data for light quarks, but run into
problems at HERA for heavy mesons and for high Q2, and at the Tevatron for W
diffractive production. I review the basic properties of the soft pomeron, and
outline the possibilities which have been considered to account for the new
data.


title: Measurement of Singly Polarized p + N(pol) Collisions at HERA

abstract:
  A summary is given on the physics potential of measuring singly polarized
proton--nucleon collisions using a polarized internal target in the 820 GeV
HERA proton beam. This summary is based upon talks given at the 2nd Meeting on
'Possible Measurements of Singly Polarized p + p(pol) and p + n(pol) Collisions
at HERA' which was held at DESY Zeuthen from August 31 to September 2, 1995 as
a follow-up to the 'Workshop on the Prospects of Spin Physics at HERA.


title:
Moduli Inflation with Large Scale Structure Produced by Topological
  Defects

abstract:
  It is tempting to inflate along one of the many flat directions that arise in
supersymmetric theories. The required flatness of the potential to obtain
sufficient inflation and to not overproduce density fluctuations occurs
naturally. However, the density perturbations (in the case of a single moduli
field) that arise from inflaton quantum fluctuations are too small for
structure formation. Here we propose that topological defects (such as cosmic
strings), which arise during a phase transition near the end of moduli
inflation can provide an alternative source of structure. The strings produced
will be `fat', yet have the usual evolution by the time of nucleosynthesis.
Possible models are discussed.


title: Top Quark Production Dynamics in QCD

abstract:
  A calculation of the total cross section for top quark production in
hadron-hadron collisions is presented based on an all-orders perturbative
resummation of initial-state gluon radiative contributions to the basic quantum
chromodynamics subprocesses. Principal-value resummation is used to evaluate
all relevant large threshold contributions. In this method there are no
arbitrary infrared cutoffs, and the perturbative regime of applicability is
well defined, two attributes that significantly reduce the estimated
uncertainty of the results. For $p\bar{p}$ collisions at center-of-mass energy
$\sqrt{s}=1.8$ TeV and a top mass of 175 GeV, we obtain
$\sigma(t\bar{t})=5.52^{+0.07}_{-0.45} pb$, in agreement with experiment.
Predicted cross sections are provided as a function of top mass in $p\bar{p}$
collisions at $\sqrt{s}=2.0$ TeV and in $p p$ collisions at CERN LHC energies.


title: Bubble chain resummation and universality

abstract:
  We propose a parameterization for contributions of an infinite set of
diagrams (bubble chains) into physical observables represented as integrals of
running coupling constant over the finite region in momentum space. The
perturbation theory part of contributions is rendered well-defined by the
principal value prescrition for treating the Landau pole while the rest is
connected to the gluon condensate in case of observables allowing the OPE
analysis. The hypothesis of universality, i.e. the use of our parameterization
for non-OPE cases, is discussed.


title:
Remarks on the UA4/2 d\sigma/dt and on the Asymptotic \sigma_T(s)
  Behavior

abstract:
  We find that the UA4/2 measurements on the real part of the forward $p \bar
p$ scattering amplitude and total cross section are consistent with each other
and also with the standard picture of the Pomeron of either ${\it ln} ^2 s$ or
${\it ln} s$ type. However the asymptotic $\sigma _T (s)$ behavior obtained
from the {\it ad hoc} parametrization fit to the $p \bar p$ total cross
sections as quoted in the Review of Particle Properties is consistent with the
analysis of the class of the analytic amplitude models that contain the ${\it
ln} ^2 s$ type Pomeron term.


title: Possible Effects of $D^0-\bar{D}^0$ Mixing in Weak $B$ Decays

abstract:
  $D^0-\bar{D}^0$ mixing at a detectable level requires the presence of new
physics and may lead to some observable effects in weak decays of $B$ mesons.
We show that $CP$ violation induced by $D^0-\bar{D}^0$ mixing can manifest
itself in the decay-rate asymmetry of $B^+_u\rightarrow D_{L(H)}l^+\nu^{~}_l$
vs $B^-_u\rightarrow D_{L(H)}l^-\bar{\nu}^{~}_l$. A rephasing-invariant
generalization of the Gronau-Wyler approach is made to determine the weak phase
shift in $B^{\pm}_u\rightarrow D_{L(H)}K^{\pm}$, which is only sensitive to the
underlying new physics in $D^0-\bar{D}^0$ mixing. We also demonstrate the
possible effect of $D^0-\bar{D}^0$ mixing on $CP$ violation in decay modes of
the type $B_d\rightarrow D_{L(H)}+(\pi^0, \rho^0, {\rm etc})$. Finally the
model of four quark families is taken as an example to illustrate how the new
physics affects $D^0-\bar{D}^0$ mixing, $B^0_d-\bar{B}^0_d$ mixing and $CP$
asymmetries in the relevant $B$ decays.


title: D^0 \to K^{\pm}\pi^{\mp} and CP Violation at a \tau-charm Factory

abstract:
  We calculate the time-dependent and time-integrated decay rates of
$(D^0\bar{D}^0)\rightarrow (K^{\pm}\pi^{\mp})(l^{\pm}X^{\mp})$ at the
$\psi(3.77)$ and $\psi(4.14)$ resonances. The possibilities to distinguish
between the effects of $D^0-\bar{D}^0$ mixing and doubly Cabibbo suppressed
decay (DCSD) are illustrated, and the signal of $CP$ violation induced by the
interplay of mixing and DCSD is discussed. Ratios of the decay rates of
$(D^0\bar{D}^0)\rightarrow (K^{\pm}\pi^{\mp})(K^{\pm}\pi^{\mp})$ to that of
$(D^0\bar{D}^0)\rightarrow (K^+\pi^-)(K^-\pi^+)$ are also recalculated by
accommodating $CP$ violation and final-state interactions.


title:
A Time-independent Way to Probe D^0-\bar D^0 Mixing at Tau-charm
  Factories

abstract:
  $D^0-\bar{D}^0$ mixing leads to the mass and width differences in the mass
eigenstates of $D^0$ and $\bar{D}^0$ mesons (measured by parameters $x^{~}_D$
and $y^{~}_D$ respectively), but their magnitudes cannot be reliably predicted
by the standard model. We show that it is possible to separately determine
$x^{~}_D$ and $y^{~}_D$ through {\it time-integrated} measurements of the
dilepton events of coherent $D^0\bar{D}^0$ decays on the $\psi(4.14)$ resonance
at a $\tau$-charm factory.


title:
A Rederivation of the Spin-dependent Next-to-leading Order Splitting
  Functions

abstract:
  We perform a new calculation of the polarized next-to-leading order splitting
functions, using the method developed by Curci, Furmanski and Petronzio. We
confirm the results of the recent calculation by Mertig and van Neerven.


title: CP Asymmetry In Neutral $B$ System At Symmetric Colliders

abstract:
  Contrary to the conventional belief, time integrated asymmetry are measurable
in selected final states in the neutral $B$ system at symmetric $e^+e^-$
colliders. They occur due to the interplay of weak and strong phases of two
different amplitudes in addition to the $B^0 - \bar B^0$ mixing. Observation of
these asymmetries would be evidence for direct CP violation in the decay
amplitudes.


title: A Possible Violation of the Equivalence Principle by Neutrinos

abstract:
  We consider the effect of a long range, flavor changing tensor interaction of
possible gravitational origin. Neutrino mixing experiments provide the most
sensitive probe to date for such forces---testing the equivalence principle at
levels below $10^{-20}$. Here we justify and generalize a formalism for
describing such effects. The constraints from neutrino mixing experiments on
gravitationally induced mixing are calculated. Our detailed analysis of the
atmospheric neutrino data confirms a remarkable result: the atmospheric
neutrino data implies the same size force as does the solar neutrino data.
Additional tests of this suggestive result are discussed.


title: Physics with ELFE

abstract:
  A 15-30 GeV continuous beam electron facility has been proposed by nuclear
physicists in Europe to study how color forces build up hadrons from quarks and
gluons. This project and its physics case are briefly reviewed. The
recommendations of NuPECC, the Nuclear Physics Committee of the European
Science Foundation are presented.


title: Form Factors of Semileptonic $M_{l3}$ Decays

abstract:
  We study in detail the kinematics of semileptonic $M_{l3}$ ($M \rightarrow
M^\prime l \nu$) decay, considering only the new models preserving all the
gauge symmetries of the Standard Model (SM), and assuming that neutrinos are
massless and left-handed as in the SM. And we present a brief review of the
recent theoretical progress on model independent constraints on the form
factors of $M_{l3}$ decays using dispersion relations. Finally we review a new
parton model approach for semileptonic $B \rightarrow D(D^*) l \nu$ decays, by
extending the inclusive parton model and by combining with the results of the
heavy quark effective theory. We also obtain the slope of the Isgur-Wise
function.


title: Small $x$ physics in deep inelastic lepton scattering

abstract:
  The perturbative QCD predictions concerning deep inelastic scattering at low
$x$ are summarized. The theoretical framework based on the leading log $1/x$
resummation and $k_t$ factorization theorem is described. The role of studying
final states in deep inelastic scattering for revealing the details of the
underlying dynamics at low $x$ is emphasised and some dedicated measurements,
like deep inelastic scattering accompanied by an energetic jet, the measurement
of the transverse energy flow and deep inelastic diffraction, are briefly
discussed.


title: The Goldstone boson equivalence theorem with fermions

abstract:
  The calculation of the leading electroweak corrections to physical transition
matrix elements in powers of $M_H^2/v^2$ can be greatly simplified in the limit
$M_H^2\gg M_W^2,\, M_Z^2$ through the use of the Goldstone boson equivalence
theorem. This theorem allows the vector bosons $W^\pm$ and $Z$ to be replaced
by the associated scalar Goldstone bosons $w^\pm$, $z$ which appear in the
symmetry breaking sector of the Standard Model in the limit of vanishing gauge
couplings. In the present paper, we extend the equivalence theorem
systematically to include the Yukawa interactions between the fermions and the
Higgs and Goldstone bosons of the Standard Model. The corresponding Lagrangian
${\cal L}_{EQT}$ is given, and is formally renormalized to all orders. The
renormalization conditions are formulated both to make connection with physical
observables and to satisfy the requirements underlying the equivalence theorem.
As an application of this framework, we calculate the dominant radiative
corrections to fermionic Higgs decays at one loop including the virtual effects
of a heavy top quark. We apply the result to the decays $H\rightarrow t\bar{t}$
and $H\rightarrow b\bar{b}$, and find that the equivalence theorem results
including fermions are quite accurate numerically for Higgs-boson masses $M_H>
400\,(350)$ GeV, respectively, even for $m_t=175$ GeV.


abstract:
  We propose a model-independent method to determine the magnitude of the
Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ from exclusive $B$ and $D$
decays. Combining information obtainable from $B\to \rho\ell\bar\nu_\ell$,
$B\to K^*\nu\bar\nu$, $D\to \rho\bar\ell\nu_\ell$ and $D\to
K^*\bar\ell\nu_\ell$, a determination of $|V_{ub}|$ is possible, with an
uncertainty from theory of around 10\%. Theoretical uncertainties in the $B\to
K^*\ell\bar\ell$ decay rate are discussed.


title: On the Lower Bound for the Higgs Boson Mass

abstract:
  We provide an alternative derivation of a lower bound on the mass of the
Higgs boson which is somewhat simpler and more direct than the derivation based
on the effective potential. For one TeV cutoff, the result is the same. For
high scale cutoff, the lower bound is increased by slightly more than the
expected uncertainty of the calculation.