title:
Kaon polarizability in the Nambu-Jona-Lasinio model at zero and finite
  temperature

abstract:
  Using recent data for the decays $f_0 \to \gamma\gamma$, $f_0 \to \pi \pi$,
we determine the mixing angle of scalar mesons in a chiral quark
$\sigma$-model. This value is employed to analyze of the kaon polarizability.
It is shown that pole diagrams from intermediate scalar mesons and their mixing
angle significantly affect the electromagnetic polarizability of charged and
neutral kaons. Our results are compared with other models and the results of
the chiral symmetry limit. The temperature dependence of the kaon
polarizabilities is investigated.


title: Single Spin Asymmetries in Inclusive Hadron Production

abstract:
  The general formalism to describe single spin asymmetries in hadron-hadron
high energy and large $p_T$ inclusive production within the QCD-improved parton
model and assuming the factorization theorem to hold for higher twist
contributions is discussed. Non zero values of the single spin asymmetries
originate from and reveal non perturbative universal properties of quarks: the
quark distribution and fragmentation analysing powers, which need not be zero,
provided the quark intrinsic motion is taken into account. A simple model is
constructed which reproduces the main features of the data on the single spin
asymmetries observed in inclusive pion production in $pp$ collisions.


title: Enhanced photon production rate on the light--cone

abstract:
  Recent studies of the high temperature soft photon production rate on the
light--cone using Braaten--Pisarski resummation techniques have found collinear
divergences present. We show that there exist a class of terms outside the
Braaten--Pisarski framework which, although also divergent, dominate over these
previously considered terms. The divergences in these new terms may be
alleviated by application of a recently developed resummation scheme for
processes sensitive to the light--cone.


title: Anomalous 4-Jet Events at LEP: a Signal of Low Scale Technicolour?

abstract:
  We suggest that the anomalous 4-jet events recently reported by ALEPH may be
the first indication of low scale technicolour. According to our interpretation
about half of the events are due to resonantly enhanced pair production of
charged technipions, of mass around 55 GeV, each decaying into a pair of jets,
the other half being due to standard processes. The resonant enhancement is due
to a nearby technirho resonance in the mass range 150-200 GeV, leading to
hugely enhanced signals at the forthcoming LEP run at $\sqrt{s}=160$ GeV since
the CM energy would be closer to the peak of the resonance.


title: Doublet-Singlet Oscillations and Dark Matter Neutrinos

abstract:
  We examine the `singlet majoron model' first introduced by Chikashige,
Mohapatra and Peccei as a simple extension of the standard model with massive
Majorana neutrinos. We can explain both the solar and the atmospheric neutrino
deficits by the oscillations between electroweak doublet and singlet neutrinos
without flavor mixing. Furthermore, while some light neutrinos can be the hot
dark matter, tau neutrino with mass of 8.9-24 MeV can be the cold dark matter
through the interaction with the majoron. Thus, we can simultaneously explain
the solar neutrino deficit, the atmospheric neutrino anomaly, and the cold and
hot dark matters only with the Majorana neutrinos.


title: Structure Functions of Electroweak Bosons and Leptons

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


title:
Renormalization and Chiral Symmetry Breaking in Quenched QED in
  Arbitrary Covariant Gauge

abstract:
  We extend a previous Landau-gauge study of subtractive renormalization of the
fermion propagator Dyson-Schwinger equation (DSE) in strong-coupling, quenched
QED_4 to arbitrary covariant gauges. We use the fermion-photon proper vertex
proposed by Curtis and Pennington with an additional correction term included
to compensate for the small gauge-dependence induced by the ultraviolet
regulator. We discuss the chiral limit and the onset of dynamical chiral
symmetry breaking in the presence of nonperturbative renormalization. We
extract the critical coupling in several different gauges and find evidence of
a small residual gauge-dependence in this quantity.


title: Neutrino Oscillations in Strong Gravitational Fields

abstract:
  Neutrino oscillations in the presence of strong gravitational fields are
studied. We look at very high energy neutrinos ($\sim $1 TeV) emanating from
Active Galactic Nuclei (AGN). It is observed that spin flavor resonant
transitions of such neutrinos may occur in the vicinity of AGN due to {\it
gravitational} effects and due to the presence of a large magnetic field ($\sim
$1 Tesla). A point to note is that matter effects (normal MSW transitions)
become negligible in comparison o gravitational effects in our scenario.


title: Propagation of Cool Pions

abstract:
  For an exact chiral symmetry which is spontaneously broken at zero
temperature, we show that at nonzero temperature, generally pions travel at
{\it less} than the speed of light. This effect first appears at next to
leading order in an expansion about low temperature. When the chiral symmetry
is approximate we obtain two formulas, like that of Gell-Mann, Oakes, and
Renner, for the static and dynamic pion masses.


title: On the $0^{++}$ Glueball Mass

abstract:
  An approximate vacuum wave functional $\Psi_0$ is proposed for
$2+1$-dimensional Yang-Mills theories. Using $\Psi_0$, one can compute the
$0^{++}$ glueball mass $M_G$ in terms of the string tension. By using the idea
of dimensional reduction, a prediction for $M_G$ can be made in $3+1$
dimensions. One finds $M_G \approx 1.5$ GeV.


title: Supersymmetry Reach of Tevatron Upgrades: A Comparative Study

abstract:
  We use ISAJET to perform a detailed comparison of the supersymmetry reach of
the current Tevatron (100~pb$^{-1}$) with that of the Main Injector
(2~fb$^{-1}$) and the proposed TeV33 upgrade designed to yield an integrated
luminosity of 25~fb$^{-1}$. Our analysis is performed within the framework of
the minimal supergravity model with gauge coupling unification and radiative
electroweak symmetry breaking. For each of these three luminosity options, we
delineate the regions of parameter space where jets plus missing energy plus 0,
1, 2 (opposite sign and same-sign dileptons), and 3 isolated lepton signals
from the cascade decays of sparticles should be visible above standard model
backgrounds. We compare these with the parameter regions where signals in the
clean isolated dilepton and trilepton channels (from chargino/neutralino and
slepton production) should be observable.


title: Can Asymptotic Series Resolve the Problems of Inflation?

abstract:
  We discuss a cosmological scenario in which inflation is driven by a
potential which is motivated by an effective Lagrangian approach to gravity. We
exploit the recent arguments \cite{ARZ} that an effective Lagrangian $L_{eff}$
which, by definition, contains operators of arbitrary dimensionality is in
general not a convergent but rather an asymptotic series with factorially
growing coefficients. This behavior of the effective Lagrangian might be
responsible for the resolution of the cosmological constant problem. We argue
that the same behavior of the potential gives a natural realization of the
inflationary scenario.


title: Possible Solution to $R_b$ -- $R_c$ Problem

abstract:
  We investigate the $R_b$--$R_c$ problem, starting from the more diffcult
$R_c$. Introducing an isosinglet charge 2/3 quark $Q$ moves both $R_c$ and
$R_b$ in the right direction. If one allows for large $c$-$Q$ {\it and} $t$-$Q$
mixings, then $R_c$ could be reduced because of singlet content of charm quark,
while $R_b$ gets enhanced by a light effective top quark mass in the loop. The
heavy quark observed at CDF would be dominantly a singlet quark, while the top
quark is lighter than $M_W$. It is necessary to introduce a second Higgs
doublet, where $H^+$ is heavy while at least one exotic neutral Higgs boson is
very light. $H^+$--$h^0$ splitting accounts for $\delta\rho$, while light $h^0$
induce fast $t\to c + h^0$ decay and hides the actual top quark at the
Tevatron. The scenario can be immediately tested at LEP II via search for light
top production (and toponium!). At Tevatron, one should search for exotic decay
modes such as $Q\to Z + X$ or $Q\to H + X$, or measure the BR for the standard
$bW$ mode. Light top search should also be renewed.


title: Like Sign Top Pair Production via $e^+e^-\to h^0A^0 \to tt\bar c\bar c$

abstract:
  We discuss the possibility and likelihood that one may observe {\it like
sign} top quark pair production at the Linear Collider. In general two Higgs
models, flavor changing couplings involving top quark could be quite sizable.
Exotic neutral Higgs bosons may decay dominantly via $t\bar c$ or $\bar tc$
channels. At the linear collider, $e^+e^- \to h^0A^0$ or $H^0A^0$ production
processes could lead to $b\bar bt\bar c$, $W^+W^-t\bar c$ or $tt\bar c\bar c$
(or $\bar t\bar tcc$) final states. These would mimic $T$-$\bar T$ mixing
effect, except that $T$ mesons do not even form.


title: Perturbative description of particle spectra at LEP-1.5

abstract:
  The recent data from LEP-1.5 on charged particle spectra are analyzed within
the analytical QCD approach.


title: QCD string in the baryon

abstract:
  The QCD-motivated constituent string model is extended to consider the
baryon. The system of three quarks propagating in the confining background
field is studied in the Wilson loop approach, and the effective action is
obtained. The resulting Lagrangian at large interquark distances corresponds to
the Mercedes Benz string configuration. Assuming the quarks to be heavy enough
to allow the adiabatic separation of quark and string junction motion and using
the hyperspherical expansion for the quark subsystem we write out and solve the
classical equation of motion for the junction. We quantize the motion of the
junction and demonstrate that the account of these modes leads to the effective
"swelling" of the baryon in comparison with the standard potential picture. We
discuss the effects of the finite gluonic correlation length which do not
affect the excited states but appear to be substantial for the baryonic ground
state, reducing the "swelling" considerably and leaving room to the short range
Coulomb force in the three quark system.


title: B Decays and CP Violation

abstract:
  We review the status of the theory and phenomenology of heavy-quark symmetry,
exclusive weak decays of $B$ mesons, inclusive decay rates and lifetimes of $b$
hadrons, and CP violation in $B$-meson decays.


title: Gauge Unification at the String Scale and Fermion Masses

abstract:
  In the context of the minimal supersymmetric standard model (MSSM), we
discuss the introduction of exotic matter below the string scale $M_X$ in order
to achieve gauge unification at $M_X$ (a constraint of a large class of string
models). The possible types of exotic matter that can realise this are
investigated and its effect on the top quark mass $m_t$ is presented. The
implementation of a theory of fermion masses which utilises the exotic matter
is briefly discussed.


title: Neutron-anti-neutron oscillation as a test of grand unification

abstract:
  We discuss the predictions for neutron-anti-neutron oscillation in various
supersymmetric and non-supersymmetric grand unified theories. It is pointed out
that in a new class of superstring inspired grand unified theories of
$E_6$-type that satisfy gauge coupling unification, breakdown of B-L symmetry
occurs at an intermediate scale leading in turn to $\Delta B=1$ type R-parity
violating interactions naturally suppressed to the level of $10^{-5}$ to
$10^{-7}$. This inturn implies an $N-\bar{N}$ transition time of order
$10^{10}$ to $10^{11}$ sec. which may be observable in the next generation of
experiments. This model also satisfies the conditions needed for generating the
cosmological baryon asymmetry of the right order of magnitude for a restricted
range of the parameter space.


title:
Tests of three-flavor mixing in long-baseline neutrino oscillation
  experiments

abstract:
  We compare the effectiveness of various tests of three-flavor mixing in
future long-baseline neutrino oscillation experiments. We analyze a
representative case of mixing in a simplified three-flavor scheme, whose
relevant parameters are one neutrino mass-square difference, $m^2$, and two
mixing angles, $\psi$ and $\phi$. We show that an unambiguous determination of
$\psi$ and $\phi$ requires flavor-appearance tests in accelerator experiments,
as well as supplementary information from reactor experiments.


title: The inverse amplitude method in Chiral Perturbation Theory

abstract:
  Based on a dispersive approach, we apply the inverse amplitude method to
unitarize one-loop SU(2) and SU(3) Chiral Perturbation Theory. Numerically, we
find that this unitarization technique yields the correct complex analytic
structure in terms of cuts and poles. Indeed, using the chiral parameter
estimates obtained from low energy experiments we obtain the poles associated
with the rho(770) and K^*(982) resonances. Just by fixing their actual masses
we obtain a parametrization of the pi-pi and pi-K phase shifts in eight
different channels. With this fit we have then calculated several low-energy
phenomenological parameters estimating their errors. Among others, we have
obtained the chiral parameters and scattering lengths, which can be relevant
for future experiments.


title: Charge and color breaking minima and constraints on the MSSM parameters

abstract:
  The MSSM potential can have unphysical minima deeper than the physically
acceptable one. We point out that their presence is quite generic in SO(10)
unification with supergravity mediated soft terms. However, at least for
moderate values of tan\beta, the physically acceptable vacuum has a life-time
longer than the universe age. Furthermore, by discussing the evolution of the
universe in an inflationary scenario, we show that the correct vacuum is the
natural expectation. This is not the tendency in more general cases. Even in
the SO(10) case, the weak assumptions necessary for this may prevent to use the
\tilde\nu h^u direction for baryogenesis a la Affleck-Dine.


title:
The Decay $D^0\to \bar K^{*0} \pi^- e^+ \nu_e$ in the Context of Chiral
  Perturbation Theory

abstract:
  We study the decay $D^0\rightarrow \bar K^{*0} \pi^- e^+ \nu_e$, using
$SU(2)_L \otimes SU(2)_R$ chiral perturbation theory for heavy charmed mesons
and vector mesons, in the kinematic regime where $p_M \cdot p_\pi/m_M$ (here $M
= D^0$ or $\bar K^{*0}$) is much smaller than the chiral symmetry breaking
scale, $\Lambda_{\chi SB}$ ( $\Lambda_{\chi SB} \sim $ 1 GeV). We present the
leading diagrams and amplitude, and calculate the rate, in the region where, to
leading order in our calculations, the $\bar K^{*0}$ is at zero recoil in the
$D^0$ rest frame. The rate thus calculated is given in terms of a known form
factor and depends on the $DD^* \pi$ coupling constant $g_D$ of the heavy
(charmed) meson chiral perturbation theory Lagrangian. A measurement of the
above decay, in the aforementioned kinematic regime, can result in the
extraction of an experimental value for $g_D$, accurate at the level of our
approximations, and give us a measure of the validity of approaches based on
chiral perturbation theory in studying similar processes.


title:
Color Dipole Systematics of Diffractive Photo- and Electroproduction of
  Vector Mesons

abstract:
  We present the first evaluation of color dipole cross section from
experimental data on diffractive photo- and electroproduction of vector mesons.
The dipole-size and energy dependence of the found dipole cross section is
consistent with expectations from the BFKL dynamics.


title: Below Threshold $Z'$ Mass and Coupling Determinations at the NLC

abstract:
  We examine the capability of the NLC to determine the mass as well as the
couplings to leptons and $b$-quarks of a new neutral gauge boson below
production threshold. By using data collected at several different values of
$\sqrt s$, we demonstrate how this can be done in a model-independent manner.
[To appear in {\it Physics and Technology of the Next Linear Collider}, eds.
D.\ Burke and M.\ Peskin]


title: Hadronic production of heavy mesons in perturbative QCD

abstract:
  In the framework of perturbative QCD in the fourth order over the $\alpha_s$
coupling constant for the production of two pairs of quarks and in the model of
weak binding of the quarks into meson, the analysis of the hadronic production
of mesons, containing $b$-quark, is performed, and a minimal transverse
momentum is determined, so that at the momenta greater than the found one, the
meson differential spectrum can be reliably described in the model of
factorization of the hard $b$-quark production and the subsequent fragmentation
into the mesons. At low transverse momenta of the meson, nonfragmentational
contributions are essential. They are determined by the complete set of QCD
diagrams in the given order over $\alpha_s$, so that the latters result in the
effect of destructive interference with the diagrams of fragmentation at
$z=2E/\sqrt{s}$ close to $1$.


title: Parton Sum Rules and Nucleon Structure Functions

abstract:
  A brief summary on the Wigner rotation effect in the understanding of the
proton spin ``crisis" related with the Ellis-Jaffe sum rule violation, and on
the proton-neutron isospin symmetry breaking explanation of the Gottfried sum
rule violation. The proton spin could be fully provided by the spin sum of
quarks if one considers the Wigner rotation effect in the measured quark
helicity distributions.


title: The x-Dependent Helicity Distributions for Valence Quarks in Nucleons

abstract:
  We derive simple relations between the polarized and unpolarized valence
quark distributions in a light-cone SU(6) quark-spectator model for nucleons.
The explicit x-dependent Wigner rotation effect for the light-flavor quarks is
calculated. It is shown that the mass difference between the scalar and vector
spectators could reproduce the up and down valence quark asymmetry that
accounts for the observed ratio $F_2^{n}/F_2^{p}$. The proton, neutron, and
deuteron polarization asymmetries, $A_1^p$, $A_1^n$, and $A_1^d$, are in
agreement with the available data by taking into account the Wigner rotation
effect. The calculated $x$-dependent helicity distributions of the up and down
valence quarks are compared with the recent results from semi-inclusive hadron
asymmetries in polarized deep inelastic scattering by the Spin Muon
Collaboration.


title: Quark Mass Effects in Deeply Inelastic Scattering

abstract:
  We argue that the difference between the structure functions corresponding to
deep inelastic scattering with and without heavy quarks in the current
fragmentation region scales at high Q^2 and fixed (low) x.


title: Role of Four-Quark Operators in the Inclusive $\Lambda_b$ Decays

abstract:
  We compute by QCD sum rules the matrix elements of the relevant four-quark
operators appearing in the expression of the $\Lambda_b$ inclusive decay rates
at the order $1/m_b^3$. The results suggest that $1/m_b^3$ corrections are not
responsible of the observed difference between the lifetime of $\Lambda_b$ and
$B_d$.


title: QCD and QED renormalization group functions - a large N_f approach

abstract:
  The large N_f self-consistency programme is reviewed. As an application the
QCD beta-function is computed at O(1/N_f) and the anomalous dimensions of
polarized twist-2 singlet operators are determined at the same order.


title: Search for quark compositeness with polarized beams at RHIC

abstract:
  Around 1999, thanks to the RHIC Spin Collaboration (RSC), the Relativistic
Heavy Ion Collider (RHIC) will be used as a polarized proton-proton collider. A
new handed interaction between quark subconstituents, which could explain the
excess of large E_T jet found by the CDF collaboration, could be at the origin
of some small parity violating effects in one-jet inclusive production. Using
spin asymmetries it is possible, at RHIC, to disentangle this new effect from
the Standard Model prediction due to QCD-ElectroWeak interferences.


title: In Search of the Next Next-to-MSSM

abstract:
  It is argued that the Next-to-MSSM (NMSSM) is unnatural from the point of
view of cosmology and fine tuning. In particular, such singlet extensions to
the MSSM do not provide a simple solution to the `$\mu$-problem'. Models with
singlets can be constructed using gauged-$R$ symmetry or target space duality.
However their superpotentials have terms in addition to those of the NMSSM.


title: Cut Diagrams for High Energy Scatterings

abstract:
  A new approach is introduced to study QCD amplitudes at high energy and
comparatively small momentum transfer. Novel cut diagrams, representing
resummation of Feynman diagrams, are used to simplify calculation and to avoid
delicate cancellations encountered in the usual approach. Explicit calculation
to the 6th order is carried out to demonstrate the advantage of cut diagrams
over Feynman diagrams.


title:
Solving the Gluon Dyson-Schwinger Equation in the Mandelstam
  Approximation

abstract:
  Truncated Dyson-Schwinger equations represent finite subsets of the equations
of motion for Green's functions. Solutions to these non-linear integral
equations can account for non-perturbative correlations. We describe the
solution to the Dyson-Schwinger equation for the gluon propagator of Landau
gauge QCD in the Mandelstam approximation. This involves a combination of
numerical and analytic methods: An asymptotic infrared expansion of the
solution is calculated recursively. In the ultraviolet, the problem reduces to
an analytically solvable differential equation. The iterative solution is then
obtained numerically by matching it to the analytic results at appropriate
points. Matching point independence is obtained for sufficiently wide ranges.
The solution is used to extract a non-perturbative beta-function. The scaling
behavior is in good agreement with perturbative QCD. No further fixed point for
positive values of the coupling is found which thus increases without bound in
the infrared. The non-perurbative result implies an infrared singular quark
interaction relating the scale Lambda of the subtraction scheme to the string
tension sigma.


title: Ambiguities in QED: Renormalons versus Triviality

abstract:
  We point out that, contrary to what is believed to hold for QCD, renormalons
are genuine in QED; i.e. the ambiguities which come with them do not require
cancellation by hypothetical non-perturbative contributions. They are just the
ambiguities characteristic of any trivial ---and thus effective--- theory. If
QED remained an isolated theory up to an energy close to its triviality scale,
these ambiguities would surely hint at new physics. This not being so, the
renormalon ambiguities in QED lead to no new physics, not even to
non-perturbative contributions within QED itself.


title: Virtual-Sparticle Threshold Effects on Large E_T Jet Cross Sections

abstract:
  We discuss the one-loop virtual-sparticle corrections to QCD jet cross
sections at large $E_T$ and large dijet invariant masses, with reference to
present Tevatron and future LHC collider experiments. We find characteristic
peaks and dips in the sparticle threshold region, due to interferences with
tree-level QCD diagrams. Their magnitudes may be several per cent of the total
jet cross section, so they might provide a useful search tool that is
complementary to the usual missing-energy signature for supersymmetry.


title: Bose Einstein Correlations and Quantum Field Theory

abstract:
  It is shown that there exists an intimate relationship between Bose Einstein
correlations and quantum field theory. On the one hand several essential
aspects of BEC cannot be understood and even formulated without second
quantization. On the other hand BEC can serve as a unique tool in the
investigation of modern field theory and in particular of the standard model.
Some new developments on this subject related to multiparticle production and
squeezed states are also discussed.


title: Physics of Top Quark at the Tevatron

abstract:
  We discuss the physics of the top quark at the Fermilab Tevatron. By the year
2000, many properties of the top quark can be measured at the Tevatron.


title: Asymmetry in the decay $\Omega^-\to\Xi^-\gamma$

abstract:
  We consider the asymmetry in the decay $\Omega^-\rightarrow\Xi^-\gamma$
assuming that a Vector Meson Dominance approach for the $s\rightarrow d\gamma$
transition gives the dominant contribution. Since in this long-distance
approximation the decay is due to a single quark transition $s\rightarrow
d\gamma$, the angular distribution asymmetry is given by the single positive
asymmetry parameter $\alpha_h = \frac{M^2_s-M^2_d}{M^2_s+M^2_d} = 0.4\pm0.1$.
We also discuss the asymmetry in $\Xi \rightarrow \Sigma^-\gamma$, which is
expected to be between -0.2 and 0.3.


title:
$O(\alpha_s^2)$ Contributions to the longitudinal fragmentation function
  in $e^+\,e^-$ annihilation

abstract:
  We present the order $\alpha_s^2$ contributions to the coefficient functions
corresponding to the longitudinal fragmentation function $F_L(x,Q^2)$. A
comparison with the leading order $\alpha_s$ result for $F_L(x,Q^2)$ shows that
the corrections are large and vary from 44\% to 67\% in the region $0.01 < x <
0.9$ at $Q^2=M_Z^2$. Our calculations also reveal that the ratio of the
longitudinal and total cross section $\sigma_L/\sigma_{\rm tot}$ amounts to
0.054. This number is very close to the most recent value obtained by the OPAL
collaboration which obtained $0.057\pm 0.005$.


title:
The $Q^2$ dependence of the hard diffractive photoproduction of vector
  meson or photon and the range of pQCD validity

abstract:
  We consider two coupled problems.
  We study the dependence on photon virtuality $Q^2$ for the semihard
quasi--elastic photoproduction of neutral vector mesons on a quark, gluon or
real photon (at $s\gg p_{\bot}^2,\;Q^2; \; p_{\bot}^2\gg \mu^2 \approx (0.3$
GeV)$^2$). To this end we calculate the corresponding amplitudes (in an
analytical form) in the lowest nontrivial approximation of perturbative QCD. It
is shown that the amplitude for the production of light meson varies very
rapidly with the photon virtuality near $Q^2=0$.
  We estimate the bound of the pQCD validity region for such processes. For the
real incident photon the obtained bound for the $\rho$ meson production is very
high. This bound decreases fast with the increase of $Q^2$, and we expect that
the virtual photoproduction at HERA gives opportunity to test the pQCD results.
The signature of this region is discussed. For the hard Compton effect the pQCD
should work good at not too high $p_{\bot}$, and this effect seems measurable
at HERA.


title:
The Chromomagnetic Dipole Operator and the B Semileptonic Branching
  Ratio

abstract:
  We consider the possibility of having a large branching ratio for the decay
$b\to s g$ coming from an enhanced Wilson coefficient of the chromomagnetic
dipole operator. We show that values of $BR(b\to s g)$ up to $\sim 10\%$ or
more are compatible with the constraints coming from the CLEO experimental
results on $BR(B\to X_s\gamma)$ and $BR(B\to X_s\phi)$. Such large values can
reconcile the predictions of both the semileptonic branching ratio and the
charm counting with the present experimental results. We also discuss a
supersymmetric model with gluino-mediated flavour violations, which can account
for such large values of $BR(b\to s g)$.


title: Chargino-Sneutrino Production in Electron-Photon Collisions

abstract:
  We study the production of charginos and sneutrinos in electron-photon
collisions within the minimal supersymmetric standard model (MSSM). The high
energy photons can be generated by Compton backscattering of intense laser
pulses off one of the beams of the Next Linear Collider (NLC). This process
could offer a significant opportunity to identify sneutrinos, which exclusively
decay invisibly into a neutrino and the LSP, since the cross sections are two
orders of magnitude higher than for the radiative production of invisible
sneutrinos. For three scenarios of gaugino-higgsino mixing the cross sections
and polarization asymmetries are computed and the resulting signatures are
compared with the SM background.


title: A light stop and electroweak baryogenesis

abstract:
  The possibility of creating baryon asymmetry at the electroweak phase
transition in the minimal supersymmetric standard model is considered for the
case when right-handed squarks are much lighter than left-handed ones. It is
shown that the usual requirement v(T_c)/T_c > 1 for baryogenesis can be
satisfied in a range of the parameters of the model, consistent with present
experimental bounds.


title: Baryons as non-topological chiral solitons

abstract:
  The present review gives a survey of recent developments and applications of
the Nambu--Jona-Lasinio model with $N_f=2$ and $N_f=3$ quark flavors for the
structure of baryons. The model is an effective chiral quark theory which
incorporates the SU(N$_f$)$_L\otimes$SU(N$_f$)$_R\otimes$U(1)$_V$ approximate
symmetry of Quantum chromodynamics. The approach describes the spontaneous
chiral symmetry breaking and dynamical quark mass generation. Mesons appear as
quark-antiquark excitations and baryons arise as non-topological solitons with
three valence quarks and a polarized Dirac sea. For the evaluation of the
baryon properties the present review concentrates on the non-linear
Nambu--Jona-Lasinio model with quark and Goldstone degrees of freedom which is
identical to the Chiral quark soliton model obtained from the instanton liquid
model of the QCD vacuum. In this non-linear model, a wide variety of
observables of baryons of the octet and decuplet is considered. These include,
in particular, electromagnetic, axial, pseudoscalar and pion nucleon form
factors and the related static properties like magnetic moments, radii and
coupling constants of the nucleon as well as the mass splittings and
electromagnetic form factors of hyperons. Predictions are given for the strange
form factors, the scalar form factor and the tensor charge of the nucleon.


title: Tensor Charges of the Nucleon in the SU(3) Chiral Quark Soliton Model

abstract:
  The tensor charges of the nucleon are calculated in the framework of the
SU(3) chiral quark soliton model. The rotational $1/N_c$ and strange quark mass
corrections are taken into account up to linear order. We obtain the following
numerical values of the tensor charges: $\delta u=1.12$, $\delta d=-0.42$, and
$\delta s=-0.008$. In contrast to the axial charges, the tensor charges in our
model are closer to those of the nonrelativistic quark model, in particular,
the net number of the transversely polarized strange quarks in a transversely
polarized nucleon $\delta s$ is compatible with zero.


title: Long range neutrino forces and the lower bound on neutrino mass

abstract:
  Stellar objects (including our Sun, other stars of main sequence, white
dwarfs, neutron stars etc.) contain strongly degenerate low energy sea of
neutrinos (in neutron stars) or antineutrinos. The presence of this sea leads
due to Pauli principle and thermal effects to effective blocking of the
long-range neutrino forces. This blocking can resolve the problem of the
unphysically large value of the self-energy of stars stipulated by many body
long-range neutrino interactions. As a consequence no lower bound on the
neutrino mass is inferred, in contrast with the statement by Fischbach.


title: Non-equilibrium symmetry restoration beyond one loop

abstract:
  We calculate the strength of symmetry restoration effects in highly
non-equilibrium states which can arise, for example, during preheating after
inflation. We show that in certain parameter range the one-loop results are
unstable, requiring summation of multiloop diagrams. We solve this problem for
the $O(N)$ model in the large $N$-limit and show that the symmetry restoration
may be less effective than what predicted by the one-loop estimate.


title: A Supersymmetric Solution to CP Problems

abstract:
  We analyze the minimal supersymmetric left-right model with
non-re\-nor\-malizable interactions induced by higher scale physics and study
its {\it CP} violating properties. We show that it: (i) solves the strong {\it
CP} problem; (ii) predicts the neutron electric dipole moment well within
experimental limits (thus solving the usual SUSY {\it CP} problem). In
addition, it automatically conserves {\it R}-parity. The key points are that
the parity symmetry forces the Yukawa couplings to be hermitean, while
supersymmetry ensures that the scalar potential has a minimum with real higgs
doublet vacuum expectation values. Gluino and B-L gaugino masses are
automatically real. The observed {\it CP} violation in the kaon system comes,
as in the Standard Model, from the Kobayashi-Maskawa-type phases. These
solutions are valid for any value of the right-handed breaking scale $M_R$, as
long as the effective theory below $M_R$ has only two Higgs doublets that
couple fully to fermions. ({\it i.e.} the theory below $M_R$ is MSSM-like.) The
potentially dangerous $SU(2)_L$ gaugino one-loop contributions to
$\bar{\Theta}$ below $M_R$ can be avoided if the left-right symmetry originates
from a unified theory in which the $SU(2)_{L,R}$ gaugino masses are real. As an
example, we show how the left-right symmetry can be embedded in an SO(10)
theory.


title:
Probing Charge-Symmetry-Violating Quark Distributions in Semi-Inclusive
  Leptoproduction of Hadrons

abstract:
  Recent experiments by the HERMES group at HERA are measuring semi-inclusive
electroproduction of pions from deuterium. We point out that by comparing the
production of $\pi^+$ and $\pi^-$ from an isoscalar target, it is possible, in
principle, to measure charge symmetry violation in the valence quark
distributions of the nucleons. It is also possible in the same experiments to
obtain an independent measurement of the quark fragmentation functions. We
review the information which can be deduced from such experiments and show the
``signature'' for charge symmetry violation in such experiments. Finally, we
predict the magnitude of the charge symmetry violation, from both the valence
quark distributions and the pion fragmentation function, which might be
expected in these experiments.


title: Associated Production of Charm and a Hard Photon

abstract:
  The two particle inclusive cross section for the reaction $p
+\bar{p}\rightarrow \gamma + c + X$ is studied in perturbative quantum
chromodynamics at order $O(\alpha ^2_s)$, for large values of the transverse
momentum of the prompt photon and charm quark. Two different techniques are
used in performing the phase-space integrals; the first is purely analytical,
and the second is a combination of analytic and Monte Carlo integration
methods. The second, more versatile technique facilitates imposition of photon
isolation restrictions and other selections of relevance in experiments.
Differential distributions are provided for various observables, and a
comparison is made with preliminary data from the CDF collaboration.


title: Kaon-Nucleus Drell-Yan Processes and Kaon Structure Functions

abstract:
  We investigate the information which could be obtained from Drell-Yan
processes with sufficiently intense beams of charged kaons on isoscalar
targets. It is found that combinations of $K^+$ and $K^-$ Drell-Yan
measurements on isoscalar nuclear targets would allow one to extract the kaon
sea quark distributions. These cross sections are also sensitive to the strange
valence quark distribution in the kaon, although one would need a significant
increase over the presently available kaon fluxes in order to extract this
quantity with sufficient accuracy.


title: Radiative decays of heavy and light mesons in a quark triangle approach

abstract:
  The radiative meson decays $V\to P\gamma$ and $P\to \gamma\gamma$ are
analyzed using the quark triangle diagram. Experimental data yield well
determined estimates of the universal quark-antiquark-meson couplings
$g_{Vq\bar{q}'}$ and $g_{Pq\bar{q}'}$ for the light meson sector. Also
predictions for the ratios of neutral to charged heavy meson decay coupling
constants are given and await experimental confirmation.


title: Background-Field Formalism in Quantum Systems

abstract:
  The background-field formalism is used extensively in fundamental approaches
to QCD to explore hadronic matrix elements of various currents. While the
lattice QCD approach is formulated in the fully-interacting Hilbert space,
which includes both QCD and background field interactions, the QCD sum-rule
formalism is traditionally developed in the pure-QCD Hilbert space. The latter
approach encounters difficulties with excited state contaminations which are
not exponentially suppressed and requires extrapolations to isolate the desired
physics. Proponents of the pure-QCD Hilbert space formalism used in the QCD
sum-rule approach have criticized the lattice QCD approach as neglecting
important physics. In this letter, the equivalence of the two approaches is
established and the flaws in the former criticisms are resolved. Finally, the
application of the fully-interacting Hilbert space formalism to the study of
electromagnetic polarizabilities is outlined.


title: Fluctuations and Entropy Indices of QCD Parton Showers

abstract:
  The branching processes in parton showers are studied in perturbative QCD for
both quark and gluon jets. The emphasis is on the nature of fluctuations of
both the parton multiplicities and the spatial patterns of the final states.
Effective measures of such fluctuations are calculated from the data obtained
by Monte Carlo simulations. The entropy indices are used to characterize
chaoticity. Both running and fixed couplings are considered. The fixed coupling
case is used to study the onset of chaos. Implications of the results are
discussed.


title: Implications of Low Energy Supersymmetry Breaking at the Tevatron

abstract:
  The signatures for low energy supersymmetry breaking at the Tevatron are
investigated. It is natural that the lightest standard model superpartner is an
electroweak neutralino, which decays to an essentially massless Goldstino and
photon, possibly within the detector. In the simplest models of gauge-mediated
supersymmetry breaking, the production of right-handed sleptons, neutralinos,
and charginos leads to a pair of hard photons accompanied by leptons and/or
jets with missing transverse energy. The relatively hard leptons and softer
photons of the single $e^+e^- \gamma \gamma + \EmissT$ event observed by CDF
implies this event is best interpreted as arising from left-handed slepton pair
production. In this case the rates for $l^{\pm} \gamma \gamma + \EmissT$ and $
\gamma \gamma + \EmissT$ are comparable to that for $l^+l^- \gamma \gamma +
\EmissT$.


title: A New Model-independent Method of Determining |V_{ub}/V_{cb}|

abstract:
  In order to determine the ratio of CKM matrix elements |V_{ub}/V_{cb}| (and
|V_{ub}|), we propose a new model-independent method based on the heavy quark
effective theory, which is theoretically described by the phase space factor
and the well-known perturbative QCD correction only. In the forthcoming
asymmetric B-experiments with microvertex detectors, BABAR and BELLE, the total
separation of b --> u semileptonic decays from the dominant b --> c
semileptonic decays would be experimentally viable. We explore the possible
experimental option: the measurement of inclusive hadronic invariant mass
distributions. We also clarify the relevant experimental backgrounds.


title: Top Mass and Isospin Breaking in Dynamical Symmetry Breaking Scenario

abstract:
  We consider a scenario where the top-quark mass is generated dynamically, and
study the implication of the present experimental values for $m_t$ and the $T$
parameter. We assume technicolor-like scenario for inducing the $W$ mass and an
effective four fermi operator for inducing the top-quark mass. We also assume
that only this four fermi operator is relevant at low energy. Then we estimate
in detail the strength $G$ and the intrinsic mass scale $M$ of the four fermi
operator. Unitarity bound is used to quantify the strength of $G$. We find that
$G/4\pi \sim {\cal O}(1)$ and that $M$ is of the order of $\Lambda_{TC} \simeq
1 \sim 2$~TeV or less. Namely the four fermi operator cannot be treated as
`point-like' around the electroweak scale. Furthermore we estimate the
contribution of the four fermi operator to the $T$ parameter. We find that the
QCD correction to the top-quark mass function reduces the contribution to the
$T$ parameter by about 40\%. By comparing the results with the present
experimental bound, we obtain another upper bound on $M$ which is typically in
several to 10~TeV region.


title: Prospect for Heavy Quarks Lighter than $M_W$

abstract:
  As the excitement surrounding the heavy top quark discovery subsides, while
the expectation for LEP II physics gathers, it is a good time to sit back and
reflect on whether energy regions available to us have been fully explored. We
emphasize that a loophole exists where heavy quarks, perhaps the actual top
quark itself, could still be hidden below $M_W$. This would typically involve
scalar induced decays of the heavy quark, and could be realized in models with
more than one Higgs doublet, e.g. MSSM. We illustrate such mechanisms with two
Higgs doublet models, the addition of singlet quarks, as well as reconsidering
a fourth family of quarks and leptons. Curiously, the present $R_b$--$R_c$
problem may be a harbinger of such scenarios. Given that LEP-II would be
running soon, and in view of the large amount of data that the Tevatron has
collected, we urge our experimental colleagues to conduct a critical analysis.


title: Possible Resonances in $\mu^+e^- \to \mu^- e^+$ Collisions

abstract:
  We study the possibility of discovering resonances in $\mu^+e^- \to \mu^-
e^+$ and $e^-e^- \to \mu^- \mu^-$ collisions. We begin with the closely related
problem of muonium--antimuonium transitions, where the experimental limit has
just been improved by one order of magnitude. We show that the new limit enters
a rather interesting mass and Yukawa coupling domain for neutral scalar bosons.
The stringent $\mu\to e\gamma$ decay is evaded by invoking some multiplicative
lepton number. Neutral and doubly charged scalar bosons give rise to
distinguishable effects in muonium transitions. Alternatively, they could show
up as spectacular resonance peaks in high energy $\mu^+e^- \to \mu^- e^+$and
$e^-e^- \to \mu^- \mu^-$ collisions, respectively. This could occur independent
of whether, but especially when, muonium-antimuonium transitions are
experimentally observed.


title: QCD Coupling Constant at Finite Temperature

abstract:
  We work out the method for evaluating the QCD coupling constant at finite
temperature ($T$) by making use of the finite $T$ renormalization group
equation up to the one-loop order on the basis of the background field method
with the imaginary time formalism. The background field method, which maintains
the explicit gauge invariance, provides notorious simplifications since one has
to calculate only the renormalization constant of the background field gluon
propagator. The results for the evolution of the QCD coupling constant at
finite $T$ reproduce partially the ones obtained in the literature. We discuss,
in particular, the origin of the discrepancies between different calculations,
such as the choice of gauge, the break-down of Lorentz invariance, imaginary
versus real time formalism and the applicability of the Ward identities at
finite $T$.


title:
$B\to D^{\ast\ast}$ semileptonic decay in covariant quark models \`a la
  Bakamjian Thomas

abstract:
  Once chosen the dynamics in one frame, for example the rest frame, the
Bakamjian and Thomas method allows to define relativistic quark models in any
frame. These models have been shown to provide, in the heavy quark limit, fully
covariant current form factors as matrix elements of the quark current
operator. They also verify the Isgur-Wise scaling and give a slope parameter
$\rho^2>3/4$ for all the possible choices of the dynamics. In this paper we
study the $L=1$ excited states and derive the general formula, valid for any
dynamics, for the scaling invariant form factors $\tau_{1/2}^{(n)}(w)$ and
$\tau_{3/2}^{(n)}(w)$. We also check the Bjorken-Isgur-Wise sum rule already
demonstrated elsewhere in this class of models.


title:
The Longitudinal Structure Function F$_L$ as a Function of F$_2$ and
  dF$_2$/dlnQ$^2$ at small x. The Next-to-Leading Analysis

abstract:
  We present a set of formulae to extract the longitudinal deep inelastic
structure function $F_L$ from the transverse structure function $F_2$ and its
derivative $dF_2/dlnQ^2$ at small $x$. Our expressions are valid for any value
of $\delta$, being $x^{-\delta}$ the behavior of the parton densities at low
$x$. Using $F_2$ HERA data we obtain $F_L$ in the range $10^{-4} \leq x \leq
10^{-2}$ at $Q^2=20$ GeV$^2$. Some other applications of the formulae are
pointed out.


title:
Anomalies in Diffractive Electroproduction of 2S Radially Excited Light
  Vector Mesons at HERA

abstract:
  We present the color dipole phenomenology of diffractive photo- and
electroproduction $\gamma^{*} N\to V(V') N$ of vector mesons ($V(1S) = \phi^0,
\omega^0, \rho^0, J/\Psi, \Upsilon$) and their radial excitations ($V'(2S) =
\phi', \omega', \rho', \Psi', \Upsilon'$). The main emphasis is related to
light vector mesons. We discuss how the energy dependence of the color dipole
cross section in conjuction with the node of the radial wave function of the
$2S$ states can lead to an anomalous $Q^2$ and energy dependence of diffractive
production of $V'(2S)$ vector mesons. The color dipole model predictions for
$V(1S)$ light vector meson production are compared with the experimental data
from the EMC, NMC, ZEUS and H1 collaborations.


title:
Constraints on the polarized gluon density in the proton from charm
  photoproduction

abstract:
  We consider the possibility of a direct determination of the polarized gluon
density in the proton using charm production with polarized beams at HERA. We
study total cross sections and distributions at leading order using different
parametrizations of the polarized gluon density. We conclude that charm
photoproduction data can be used to constrain the polarized gluon density in
the proton if an integrated luminosity of 100~pb$^{-1}$ will be achieved at
HERA.


title:
Large Transverse Momentum Jet Production and DIS Distributions of the
  Proton

abstract:
  We have calculated the single jet inclusive cross section as measured at
Fermilab in next-to-leading order QCD using recent parton distributions of the
CTEQ collaboration. We studied the scheme dependence of the jet cross section
by employing the $\overline{\mbox{MS}}$ and DIS factorization schemes
consistently. For $E_T > 200$ GeV, we find that the cross section in the DIS
scheme is larger than in the $\overline{\mbox{MS}}$ scheme yielding a
satisfactory description of the CDF data over the whole $E_T$ range in the DIS
scheme.


title:
Relationship Between the Kobayashi-Maskawa and Chau-Keung Presentations
  of the Quark Mixing Matrix

abstract:
  We discuss the formulas for one-to-one correspondence between the two popular
parametrizations of the quark mixing matrix and the confidence limits for the
mixing parameters.


title: The Perturbative Resummed Series for Top Production

abstract:
  Our calculation of the total cross section for inclusive production of
$t\bar{t}$ pairs in hadron collisions is summarized. The principal ingredient
of this calculation is resummation of the universal leading-logarithm effects
of gluon radiation to all orders in the quantum chromodynamics coupling
strength, restricted to the region of phase space that is manifestly
perturbative. We present predictions of the physical cross section as a
function of top quark mass in proton-antiproton reactions at center-of-mass
energies of 1.8 and 2.0 TeV.


title:
Jet Quenching in the Opposite Direction of a Tagged Photon in
  High-Energy Heavy-Ion Collisions

abstract:
  We point out that events associated with large $E_T$ direct photons in
high-energy heavy-ion collisions can be used to study jet energy loss in dense
matter. In such events, the $p_T$ spectrum of charged hadrons from jet
fragmentation in the opposite direction of the tagged photon is estimated to be
well above the background which can be reliably subtracted at moderately large
$p_T$. We demonstrate that comparison between the extracted fragmentation
function in $AA$ and $pp$ collisions can be used to determine the jet energy
loss and the interaction mean-free-path in the dense matter produced in
high-energy heavy-ion collisions.


title:
pQCD-based Approach to Parton Production and Equilibration in
  High-Energy Nuclear Collisions

abstract:
  A pQCD-based model for parton production and equilibration in
ultrarelativistic heavy-ion collisions is reviewed. The model combines pQCD
processes including initial and final state radiations together with string
phenomenology for nonperturbative soft processes. Nuclear effects on the
initial parton production, such as multiple parton scattering and nuclear
shadowing of parton distribution functions are considered. Comparisons with
existing data are made and further tests of the model to constrain model
parameters are proposed. With the obtained space-time history of the parton
production, evolution of the minijet gas toward a fully equilibrated parton
plasma is studied. Direct probes of the early parton dynamics, such as
pre-equilibrium photon and dilepton production, open charm production, $J/\psi$
suppressionand jet quenching are also reviewed.


title: Exact Parametrization of The Mass Matrices and The KM Matrix

abstract:
  We analyze properties of general quark mass matrices. The up and down part
quark mass matrices are written in terms of six dimensionless parameters and
six quark masses. It is shown that two of the former six dimensionless
parameters can be chosen to be any value. Once values for these two parameters
are chosen, Kobayashi-Maskawa matrix is written in terms of the remaining four
parameters. Our results are given analytically without any approximation.


title: Strangeness Enhancement Scenarios: Fireball or Independent Strings?

abstract:
  Due to the long-standing discrepancy between NA35 and NA36 data on $\Lambda$
production, two drastically different scenarios of strangeness enhancement are
still possible. Independent string models, such as the dual parton model, lead
to results close to the NA36 data. On the contrary, the NA35 results can only
be described by introducing full final state rescattering of the produced
particles. The corresponding predictions for central $Pb$-$Pb$ collisions at
CERN energies differ by a factor 3 to 4. Preliminary data on the net proton
($p$-$\bar{p}$) rapidity distribution in $Pb$-$Pb$ collisions favor the
independent string scenario.


title: Double Charged Higgs Bosons Production in $e^-e^-$--Collisions

abstract:
  In the framework of the models with Higgs triplets, double charged Higgs
bosons production in the processes $e^-e^-\to\delta ^{--}_{L,R}\gamma$ are
considered.


title: Z' Physics

abstract:
  The limits on extra neutral gauge bosons, which could be reached at LEP2, are
reviewed. Exclusion and discovery limits are discussed for f\bar f and WW
production.


title: Two-photon processes of pseudoscalar mesons in a Bethe-Salpeter approach

abstract:
  We evaluate the $\pi^0\gamma^* \to \gamma$ transition form factor and
$\gamma\gamma$ decay widths for $\pi^0, \eta_c$ and $\eta_b$ treated as
$q\bar{q}$ bound states in the Bethe-Salpeter formalism, incorporating the
dynamical chiral symmetry breaking and the Goldstone nature of the pion. In the
chiral limit, the Abelian axial anomaly is incorporated analytically in our
coupled Schwinger-Dyson and Bethe-Salpeter approach, which is also capable of
quantitatively describing systems of heavy quarks, concretely $\eta_c$ and
possibly $\eta_b$.


title:
CP violation and CKM phases from angular distributions for $B_s$ decays
  into admixtures of CP eigenstates

abstract:
  We investigate the time-evolutions of angular distributions for $B_s$ decays
into final states that are admixtures of CP-even and CP-odd configurations. A
sizable lifetime difference between the $B_s$ mass eigenstates allows a probe
of CP violation in time-dependent untagged angular distributions. Interference
effects between different final state configurations of $B_s\to D^{*+}_s
D^{*-}_s$, $J/\psi \phi$ determine the Wolfenstein parameter $\eta$ from
untagged data samples, or -- if one uses $|V_{ub}|/|V_{cb}|$ as an additional
input -- the notoriously difficult to measure CKM angle $\gamma$. Another
determination of $\gamma$ is possible by using isospin symmetry of strong
interactions to relate untagged data samples of $B_s\to K^{\ast+} K^{\ast-}$
and $B_s\to K^{\ast0} \overline{K^{\ast0}}$. We note that the untagged angular
distribution for $B_s\to\rho^0 \phi$ provides interesting information about
electroweak penguins.


title:
CP violation and the CKM angle $\gamma$ from angular distributions of
  untagged $B_s$ decays governed by $\bar b\to\bar c u\bar s$

abstract:
  We demonstrate that time-dependent studies of angular distributions for $B_s$
decays caused by $\bar b\to\bar cu\bar s$ quark-level transitions extract
cleanly and model-independently the CKM angle $\gamma$. This CKM angle could be
cleanly determined from untagged $B_s$ decays alone, if the lifetime difference
between the $B_s$ mass eigenstates $B_s^L$ and $B_s^H$ is sizable. The
time-dependences for the relevant tagged and untagged observables are given
both in a general notation and in terms of linear polarization states and
should exhibit large CP-violating effects. These observables may furthermore
provide insights into the hadronization dynamics of the corresponding exclusive
$B_s$ decays thereby allowing tests of the factorization hypothesis.


title: Light Gravitinos as Mixed Dark Matter

abstract:
  In theories with a gauge-mediated mechanism of supersymmetry breaking the
gravitino is likely to be the lightest superparticle and, hence, a candidate
for dark matter. We show that the decay of the next-to-lightest superparticle
into a gravitino can yield a non-thermal population of gravitinos which behave
as a hot dark matter component. Together with the warm component, which is
provided by the population of gravitinos of thermal origin, they can give rise
to viable schemes of mixed dark matter. This realization has some specific and
testable features both in particle physics and astrophysics. We outline under
which conditions the mechanism remains viable even when R parity is broken.


title: Amplification of pionic instabilities in high-energy collisions?

abstract:
  Considering a variety of dynamical scenarios within the linear sigma model,
we examine the conditions for pionic modes to be amplified as the chiral field
relaxes towards the normal vacuum following the transient restoration of
approximate chiral symmetry in a high-energy collision. While Bjorken-type
longitudinal expansions appear to be insufficient for amplification for occur,
analoguos expansions in two or three dimensions may enhance the low-energy
power spectrum by up to an order of magnitude.


title: A Grand Unified Supersymmetric Theory of Flavor

abstract:
  A grand unified $SU(5)$ theory is constructed with a hierarchical breaking of
a $U(2)$ flavor symmetry. The small parameters of the squark and slepton mass
matrices, necessary to solve the supersymmetric flavor-changing problem, and
the inter-generational quark and lepton mass hierarchies are both generated
from the $U(2)$ symmetry breaking parameters. The flavor interactions of the
theory are tightly constrained, with just 10 free real parameters for both the
fermion and scalar sectors. All but one of the 8 small fermion mass ratios, and
all of the 3 small Cabibbo-Kobayashi-Maskawa mixing angles, can be understood
without introducing small dimensionless Yukawa parameters. Predictions are made
for 2 of the Cabibbo-Kobayashi-Maskawa mixing angles and for 2 of the fermion
masses. The six flavor mixing matrices which appear at the neutralino vertices,
and which in general are arbitrary unitary matrices, are determined in terms of
just a single free parameter.


title:
The process $e^+e^-\to b\bar bW^+W^-$ at the Next Linear Collider in the
  Minimal Supersymmetric Standard Model

abstract:
  The complete matrix element for $e^+e^-\rightarrow b\bar b W^+W^-$ is
computed at tree-level within the Minimal Supersymmetric Standard Model. Rates
of interest to phenomenological analyses at the Next Linear Collider are given.
In particular, we study: - $t\bar t$ production and decay $t\bar t\ar
(bW^+)(\bar bW^-)$; - $ZH$ production followed by $Z\ar b\bar b$ and $H\ar
W^+W^-$; - $AH$ production followed by $A\ar b\bar b$ and $H\ar W^+W^-$; -
$hW^+W^-$ production followed by $h\ar b\bar b$. Top and Higgs finite width
effects are included, as well as all those of the irreducible backgrounds.


title: Constituent Quark Model versus Nonperturbative QCD

abstract:
  We discuss a few, apparently different (but actually, tightly related)
problems: 1. The relation between QCD and valence quark model, 2. The
asymptotic behavior of the nonperturbative pion wave function $\psi(\k, x)$ at
$x\rightarrow 0,~1, \k \rightarrow \infty$ and 3. The dimensional counting
rules in the intermediate region of energy. The analysis is based on such
general methods as dispersion relations, duality and PCAC. We calculate the
asymptotic behavior of the wave function ($wf$) at the end-point region
($x\rightarrow 1$ and $\k\rightarrow\infty$) by analysing the corresponding
large $n-$th moments in transverse $\la\vec{k}_{\perp}^{2n}\ra \sim n!$ and
longitudinal $\la (2x-1)^n\ra \sim 1/n^2$ directions. This information fixes
the asymptotic behavior of $wf$ at large $\k$ ( which is turned out to be
Gaussian commonly used in the phenomenological analyses). We discuss some
applications of the obtained results. In particular, we calculate the
nonleading ``soft" contribution to the pion form factor at intermediate
momentum transfer. We argue, that due to the specific properties of $\psi(\k,
x)$, the corresponding contribution can temporarily {\bf simulate} the leading
twist behavior in the extent region of $ Q^2 $. The same effect also takes
place for the nucleon formfactor. Such a mechanism, if it is correct, would be
an explanation of the phenomenological success of the dimensional counting
rules at available, very modest energies for many different processes. We
discuss some inclusive amplitudes also.


title:
Diffraction dissociation, an important background to photon-photon
  collisions via heavy ion beams at LHC

abstract:
  The cross sections for the production of hadrons in quasi-real photon-photon
collisions in proton-proton and heavy ion interactions are compared with the
corresponding cross sections for central diffraction and for photon-pomeron
collisions. The signatures, heavy ions or protons with only slightly changed
momenta together with two large rapidity gaps and a cluster of produced hadrons
in the central region, are nearly identical in all three processes. Therefore,
it will be rather difficult to distinguish the reactions experimentally. It is
found, that central diffraction is the dominant process in collisions of
protons, light and medium-heavy ions. The photon-pomeron and photon-photon
processes have quite similar cross sections in collisions of heavy ions like
lead.


title: On the Light Cone Singularity of the Thermal Effective Expansion

abstract:
  We consider a scalar massless quantum field model, at finite temperature $T$,
both renormalizable and asymptotically free. Focussing on the singular
structure of the effective perturbation theory about the light cone, several
new insights are put forth, regarding the interplay between hard thermal loop
resummation and the overall compensation of collinear singularities.


title: IR-Renormalon Contribution to the Polarized Structure Function $g_1$

abstract:
  An estimation of the higher twist contribution to the polarized nonsinglet
structure function $g_1$ is given. Its first moment is generally assumed to be
small but this could be due to a cancellation of its contribution in different
Bjorken-$x$ ranges. We estimate the magnitude of $g_1^{tw4}$ as a function of
$x$ in the framework of the renormalon method. The calculated
higher-twist-correction to $g_1$ turn out to be in fact small for all $x$
values. The correction to the determination of the nonsinglet matrix element
$d_{NS}^{(2)}$ from data for transversely nucleon polarization due to the
calculated higher twist effects is of order $10\%$.


title: The Scalar Sector of 3-3-1 Models

abstract:
  We study the mass spectrum and the eigenstates of the scalar sectors in 3-3-1
models. We show that, in one of the models, the physical scalar masses lead to
theoretical constraints to the vacuum expectation values. The models allow very
light Higgs bosons. One of the neutral scalars can be identified with the
standard model one.


title:
Color dipole phenomenology of diffractive electroproduction of light
  vector mesons at HERA

abstract:
  We develop the color dipole phenomenology of diffractive photo- and
electroproduction $\gamma^{*}\,N\rightarrow V(V')\,N$ of light vector mesons
($V(1S) = \phi^0, \omega^0, \rho^0$) and their radial excitations ($V'(2S) =
\phi', \omega', \rho'$). The node of the radial wave function of the $2S$
states in conjunction with the energy dependence of the color dipole cross
section is shown to lead to a strikingly different $Q^2$ and $\nu$ dependence
of diffractive production of the $V(1S)$ and $V'(2S)$ vector mesons. We discuss
the restoration of flavor symmetry and universality properties of production of
different vector mesons as a function of $Q^{2}+m_{V}^{2}$. The color dipole
model predictions for the $\rho^{0}$ and $\phi^{0}$ production are in good
agreement with the experimental data from the EMC, NMC, ZEUS and H1
collaborations. We present the first direct evaluation of the dipole cross
section from these data.


title: The axial anomaly and the conversion of gluons into photons

abstract:
  The axial anomaly in the divergence of the singlet axial current in QCD $+$
QED leads to low-energy theorems for the matrix element of this operator
equation over vacuum and two--photon states and for the matrix element over
vacuum and two--gluon states. The solution of these theorems is related only to
the nonperturbative phenomena. These matrix elements are calculated in
instanton vacuum generated N-JL type quark model for arbitrary $N_f .$ It is
shown that this model does satisfy the low-energy theorems.


title: The Exclusive Decay $B\to\rho e \nu$ Beyond Model Calculations

abstract:
  Due to its comparatively theoretical ``simplicity'', the decay channel
$B\to\rho e \nu$ offers one of the best possibilities to determine the CKM
matrix element $|V_{ub}|$ accurately. I present a new calculation of the
relevant hadronic form factors from light-cone sum rules. I also review the
results from lattice calculations and find that they agree with the results
from light-cone sum rules where comparison is possible.\\ This paper relies on
work done in collaboration with V.M.\ Braun.


title: No Lambda oscillations

abstract:
  We examine a recently published calculation which predicts an oscillatory
behaviour for the decay of Lambdas produced together with a neutral kaon, and
proposes a new expression for the wavelength of kaon strangeness oscillations.
We modify the calculation by imposing the requirement that the interference of
the K_L and K_S components of the kaon wave function occurs at a specific
space-time point. With this requirement, the unusual results predicted vanish,
and the conventional results are recovered.


title: Supersymmetric Electroweak Phase Transition: Beyond Perturbation Theory

abstract:
  We compute the three-dimensional effective action for the minimal
supersymmetric standard model, which describes the light modes of the theory
near the finite-temperature electroweak phase transition, keeping the one-loop
corrections from the third generation quarks and squarks. Using the lattice
results of Kajantie {\it et al.}\ for the phase transition in the same class of
3-D models, we find that the strength of the phase transition is sufficient for
electroweak baryogenesis, in much broader regions of parameter space than have
been indicated by purely perturbative analyses. In particular we find that,
while small values of $\tan\beta$ are favored, positive results persist even
for arbitrarily large values of $\tan\beta$ if the mass of the $A^0$ boson is
between 40 and 120 GeV, a region of parameters which has not been previously
identified as being favorable for electroweak baryogenesis.


title: High energy proton acceleration in dissolving plasma clots

abstract:
  We consider the acceleration of particles (protons) in a plasma clot by an
induced field which appears due to the dissolving of the clot. The mechanism of
this acceleration is based on a model where the clot consists of double flat
moving current layers. It is assumed that the currents flow in opposite
directions, while the clot moves in a perpendicular one. It is shown that
protons can reach the highest observed energy (of the order of $10^{11}-
10^{12}$GeV), providing that the size of the clot is large enough.


title: Natural Quark Mass Patterns

abstract:
  We incorporate the idea of natural mass matrices into the construction of
phenomenologically viable quark mass matrix patterns. The general texture
pattern for natural Hermitian mass matrices is obtained and several
applications of this result are made.


title: Fermion Masses and Mixings in a String Inspired Model

abstract:
  In the context of Calabi-Yau string models we explore the origin of
characteristic pattern of quark-lepton masses and the CKM matrix. The discrete
$R$-symmetry $Z_K \times Z_2$ is introduced and the $Z_2$ is assigned to the
$R$-parity. The gauge symmetry at the string scale, $SU(6) \times SU(2)_R$, is
broken into the standard model gauge group at a very large intermediate energy
scale. At energies below the intermediate scale down-type quarks and also
leptons are mixed with unobserved heavy states, respectively. On the other
hand, there are no such mixings for up-type quarks. Due to the large mixings
between light states and heavy ones we can derive phenomenologically viable
fermion mass hierarchies and the CKM matrix. Mass spectra for
intermediate-scale matter beyond the MSSM are also determined. Within this
framework proton lifetime is long enough to be consistent with experimental
data. As for the string scale unification of gauge couplings, however,
consistent solutions are not yet found.


title:
The present theoretical error on the Bhabha scattering cross section in
  the luminometry region at LEP

abstract:
  The results concerning the theoretical evaluation of the small-angle Bhabha
Scattering cross section obtained during the Workshop on Physics at LEP2 (CERN,
Geneva, Switzerland, 1995) by the Working Group ``Event Generators for Bhabha
Scattering'' are summarized. The estimate of the theoretical error on the cross
section in the luminometry region is updated.


title: A scenario for high-energy gamma-gamma interactions

abstract:
  A real photon has a complicated nature, whereby it may remain unresolved or
fluctuate into a vector meson or a perturbative q-qbar pair. In gamma-gamma
events, this gives three by three combinations of the nature of the two
incoming photons, and thus six distinct event classes. The properties of these
classes are partly constrained by the choices already made in our related
gamma-p model. It is therefore possible to predict the energy-dependence of the
cross section for each of the six components separately. The total cross
section gives support to the idea that a simple factorized ansatz with a
pomeron and a reggeon term can be a good approximation. Event properties
undergo a stepwise evolution from p-p to gamma-p to gamma-gamma events, with
larger charged multiplicity, more transverse energy flow and a higher jet rate
in the latter process.


title: Zeroes for e+e- \to \bar{f} f cross section and search for new physics

abstract:
  We suggest returning to a different presentation of the e+e- \to \bar{f} f
data off the Z peak, with the hope of using zeroes of specific amplitudes to
enhance the sensitivity to new physics.


title: Meson bound states in multiflavour massive Schwinger model

abstract:
  The problem of meson bound states with $N_f$ massive fermions in two
dimensional quantum electrodynamics is discussed. We speculate about the
spectrum of the lightest particles by means of the effective semiclassical
description. In particular, the systems of fundamental fermions with $SU(2)$
and $SU(3)$ flavour symmetries broken by massive terms are investigated.


title: Glueballs and Hybrid Mesons

abstract:
  The status of non-perturbative QCD calculations for mesons with gluonic
excitation is presented. Lattice results for the glueball spectrum are
reviewed. For hybrid mesons, the heavy quark results are summarised and new
results are presented for light quarks. Preliminary results for the spectrum of
light-quark hybrid mesons indicate substantial mixing with quark model states
for non-exotic $J^{PC}$. For the exotic $J^{PC}$ hybrid mesons, the
$J^{PC}=1^{-+}$, $0^{+-}$ and $2^{+-}$ states are explored.


title:
Nucleon number dependence of longitudinal radii in ion-ion collisions as
  a signature of the onset of collective expansion

abstract:
  In an attempt to disentangle the effects of nuclear geometry from those of
nuclear geometry we study dependence of longitudinal radius on nucleon numbers
of colliding nuclei within a simple model of multiple nucleon- nucleon
collisions.We discuss two approaches to resulting simple formula.In the former
the data up to S-Au can be described by nuclear geometry at the price of two
parameters,but R_L for Pb-Pb is significantly larger than geometry can
accomodate, indicating an onset of a new dynamics. In the latter even
collisions induced by lighter ions give evidence of some collective behaviour
and the increase of R_L for Pb-Pb indicates again the onset of a new dynamics.


title: Production of scalar $K\bar K$ molecules in $\phi$ radiative decays

abstract:
  The potentialities of the production of the scalar $K\bar K$ molecules in the
$\phi$ radiative decays are considered beyond the narrow resonance width
approximation. It is shown that $BR(\phi\rightarrow\gamma
f_0(a_0)\rightarrow\gamma\pi\pi(\pi\eta))\approx (1\div 2)\times 10^{-5}\
,\BR(\phi\rightarrow\gamma (f_0+a_0)\rightarrow\gamma K^+K^-)\alt 10^{-6}$ and
$BR(\phi\rightarrow\gamma (f_0+a_0) \to \gamma K^0\bar K^0)\alt 10^{-8}$. The
mass spectra in the $\pi\pi\ ,\ \pi\eta\ ,\ K^+K^-\ ,\ K^0\bar K^0$ channels
are calculated. The imaginary part of the amplitude $\phi\rightarrow\gamma
f_0(a_0)$ is calculated analytically. It is obtained the phase of the scalar
resonance production amplitude that causes the interference patterns in the
reaction $e^+e^-\rightarrow\gamma \pi^+\pi^-$ in the $\phi$ meson mass region.


title: Baryogenesis and thermal history after inflation

abstract:
  The basic idea of baryogenesis is lectured to introduce non-experts to this
subject. Some recent topics, necessarily subjective in view of short time
limitation, are also presented to show how the initial condition for
baryogenesis is realized in the new framework of inflation.


title: Matter induced rho-omega mixing

abstract:
  A novel mechanism for $\rho-\omega$ mixing induced by neutron-proton
asymmetry in nuclear matter is uncovered and the variation of the mixing angle
with the extent of asymmetry is presented.


title: Status of neutrino mixing

abstract:
  Talk presented at the 7th International Workshop on Neutrino Telescopes,
Venezia, February 1996.


title:
Comment on ``Relativistic kinetic equations for electromagnetic, scalar
  and pseudoscalar interactions''

abstract:
  It is found that the extra quantum constraints to the spinor components of
the equal-time Wigner function given in a recent paper by Zhuang and Heinz
should vanish identically. We point out here the origin of the error and give
an interpretation of the result. However, the principal idea of obtaining a
complete equal-time transport theory by energy averaging the covariant theory
remains valid. The classical transport equation for the spin density is also
found to be incorrect. We give here the correct form of that equation and
discuss briefly its structure.


title:
Neutrino Dispersion in Magnetized Media and Spin Oscillations in the
  Early Universe

abstract:
  We derive general expressions for the neutrino dispersion relation in a
magnetized plasma with a wide range of temperatures, chemical potentials, and
magnetic field strengths. If the electron and proton chemical potentials
vanish, as in the early Universe, there is no magnetization contribution to the
neutrino refractive index to leading order in the Fermi coupling constant,
contrary to claims in the recent literature. Therefore, as long as the magnetic
field satisfies $B\simleq T^2$, the neutrino refractive index in the early
Universe is dominated by the standard ``non-local term''. If neutrinos are
Dirac particles with magnetic moment $\mu$, then their right-handed components
are thermally populated before the nucleosynthesis epoch by magnetically
induced spin oscillations if $\mu B_0 \agt 10^{-6}\mu_{\rm B}\,{\rm gauss}$,
where $\mu_{\rm B}=e/2m_e$ is the Bohr magneton and $B_0$ is a large-scale
primordial magnetic field at $T_0\approx 1\,\rm MeV$. For a typically expected
random field distribution, even smaller values for $\mu B_0$ would suffice to
thermalize the right-handed Dirac components.


title: Extending the Standard Model Using Charge Quantisation Rules

abstract:
  We examine extensions of the Standard Model (SM), basing our assumptions on
what has already been observed; we don't consider anything fundamentally
different, such as grand unification or supersymmetry, which is not directly
suggested by the SM itself. We concentrate on the possibility of additional low
mass fermions (relative to the Planck mass) and search for combinations of
representations which don't produce any gauge anomalies. Generalisations of the
SM weak hypercharge quantisation rule are used to specify the weak hypercharge,
modulo 2, for any given representation of the non-abelian part of the gauge
group. Strong experimental constraints are put on our models, by using the
renormalisation group equations to obtain upper limits on fermion masses and to
check that there is no U(1) Landau pole below the Planck scale. Our most
promising model contains a fourth generation of quarks without leptons and can
soon be tested experimentally.


title:
${\cal O} (\alpha^2)$ Next-to-Leading Photonic Corrections to
  Small-Angle Bhabha Scattering in the Structure Function Formalism

abstract:
  A general method for computing ${\cal O} (\alpha^2)$ and higher-order
next-to-leading photonic corrections is presented and applied to the precision
calculation of the small-angle Bhabha scattering cross section in the
phase-space region of interest for the luminosity measurement at LEP. The
formulation is based on a proper matching of exact $\cal O (\alpha)$ results
with higher-order corrections in the Structure Function formalism. The results
of the approach are analytically compared with theoretical calculations, both
for $s$- and $t$-channel processes, available for simple Event Selections.
Numerical predictions for realistic Event Selections are also provided and
critically compared with the ones existing in the literature.


title: Eikonalized mini-jet cross-sections in $\gamma \gamma$ collisions

abstract:
  In this note we assess the validity and uncertainties in the predictions of
the eikonalised mini-jet model for $\sigma^{inel}_{\gamma \gamma}$. We are able
to find a choice of parameters where the predictions are compatible with the
current data. Even for this restricted range of parameters the predictions at
the high c.m. energies, which can be reached at the TeV energy $e^+e^-$
colliders, differ by about $\pm 25\%$. LEP 2 data can help pinpoint these
parameters and hence reduce the uncertainties in the predictions.


title:
Mini-jet Total Cross-sections and Overlap Functions through
  Bloch-Nordsieck Summation

abstract:
  Predictions for total inelastic cross-sections for photon induced processes
are discussed in the context of the QCD-inspired minijet model. Large
theoretical uncertainties exist, some of them related to the parton
distributions of hadrons in impact parameter space. A model for such
distribution is presented, based on soft gluon summation. This model
incorporates (the salient features of distributions obtained from) the
intrinsic transverse momentum behaviour of hadrons. Under the assumption that
the intrinsic behaviour is dominated by soft gluon emission stimulated by the
scattering process, the b-spectrum becomes softer and softer as the scattering
energy increases. In minijet models for the inclusive cross-sections, this will
counter the increase from $\sigma_{jet}$ .


title: Neutrino Chiral Oscillations

abstract:
  A localized wave packet exhibits under certain conditions zitterbewegung. A
similar phenomenon occurs for the chirality of a massive particle. In the case
of massive neutrinos, since they are detected via the V-A weak charged
currents, this oscillation may even explain the ``missing'' solar neutrino
experiments. The neutrino remains a mass eigenstate but contains an almost
sterile right-handed component. This qualitative discussion opens up a number
of interesting physical considerations.


title: A Fresh Look at the B Semileptonic Branching Ratio and Beauty Lifetimes

abstract:
  We discuss two problems in the theory of heavy-quark decays: an understanding
of the semileptonic branching ratio of $B$ mesons, and of the lifetime ratio
$\tau(\Lambda_b)/\tau(B^0)$. We also present a model-independent study of
spectator contributions to the lifetimes of beauty hadrons.


title: Electroweak and Flavor Dynamics at Hadron Colliders

abstract:
  We catalog the principal signatures of electroweak and flavor dynamics at
$\pbarp$ and $pp$ colliders for use at the 1996 Snowmass Workshop on New
Directions in High Energy Physics. The framework for dynamical symmetry
breaking we assume is technicolor, with a walking coupling $\atc$, and extended
technicolor. The reactions discussed occur mainly at subprocess energies
$\rshat \simle 1\,\tev$. They include production of color-singlet and octet
technirhos and their decay into pairs of technipions, longitudinal weak bosons,
or jets. Technipions, in turn, decay predominantly into heavy fermions. Many of
these signatures are also expected to occur in topcolor-assisted technicolor.
Several particles specific to this new scenario are discussed. Additional
signatures of flavor dynamics, associated with quark and lepton substructure,
may be sought in excess production rates for high $E_T$ and invariant mass
dijets and dileptons. An important feature of these processes is that they
exhibit fairly central angular and rapidity distributions.


title: The heavy top quark and supersymmetry

abstract:
  Three aspects of supersymmetric theories are discussed: electroweak symmetry
breaking, the issues of flavor, and gauge unification. The heavy top quark
plays an important, sometimes dominant, role in each case. Additional
symmetries lead to extensions of the standard model which can provide an
understanding for many of the outstanding problems of particle physics. A
broken supersymmetric extension of spacetime allows electroweak symmetry
breaking to follow from the dynamics of the heavy top quark; an extension of
isospin provides a constrained framework for understanding the pattern of quark
and lepton masses; and a grand unified extension of the standard model gauge
group provides an elegant understanding of the gauge quantum numbers of the
components of a generation. Experimental signatures for each of these
additional symmetries are discussed.


title: Width Difference in the $B_s-\bar{B_s}$ System

abstract:
  We use the heavy quark expansion to investigate the width difference
$\Delta\Gamma_{B_s}$ between the $B_s$ mass eigenstates. The corrections of
${\cal O}(\Lambda_{QCD}/m_b)$ and ${\cal O}(m_s/m_b)$ to the leading order
expression in the operator product expansion are derived and estimated to yield
a sizable reduction of the leading result for $\Delta\Gamma_{B_s}$ by typically
$30\%$. For completeness we also quantify small effects due to penguin
operators and CKM suppressed contributions. Based on our results we discuss the
prediction for $(\Delta\Gamma/\Gamma)_{B_s}$ with particular emphasis on
theoretical uncertainties. We find
$(\Delta\Gamma/\Gamma)_{B_s}=0.16^{+0.11}_{-0.09}$, where the large error is
dominated by the uncertainty in hadronic matrix elements. An accuracy of about
$10\%$ in $(\Delta\Gamma/\Gamma)_{B_s}$ should be within reach, assuming
continuing progress in lattice calculations. In addition we address
phenomenological issues and implications of a $\Delta\Gamma_{B_s}$ measurement
for constraints on $\Delta M_{B_s}$ and CKM parameters. We further consider in
some detail the lifetime ratio $\tau(B_s)/\tau(B_d)$ and estimate that, most
likely, $|\tau(B_s)/\tau(B_d)-1|<1\%$.


title:
Errors in Lattice Extractions of alpha_s Due to Use of Unphysical Pion
  Masses

abstract:
  We investigate the errors due to the use of unphysical values of light quark
masses in lattice extractions of $\alpha_s$. A functional form for the pion
mass dependence of the quarkonium mass splittings ($\Delta m$) is given as an
expansion in $m_\pi/(4\pi f_\pi)$ and $m_\pi r_B$, where $r_B$ is the
quarkonium Bohr radius. We find that, to lowest order,$\Delta m\simeq A+B
m_\pi^2$, where the scale of $B$ is given by $f_\pi^2 r_B^3$. To order
$m_\pi^4$ there are four unknown coefficients, however, utilizing multipole and
operator product expansions, symmetry arguments eliminate one of the four
unknowns. Using the central values for the lattice spacings which were
extracted using two different, unphysical values for the pion mass, we find
that the errors introduced by extrapolating to the physical regime are
comparable to the errors quoted due to other sources. Extrapolation to physical
values of the pion mass {\it increases} the value of $\alpha_s(M_Z)$, bringing
its value closer to the high energy extractions.


title: Lower scaling dimensions of quarks and gluons and new energy scales

abstract:
  We consider the possibility that quarks and gluons, due to confinement, have
lower scaling dimensions. In such a case there appear naturally new energy
scales below which the standard theory is recovered. Arguments are given
whereby for dimension $1/2$ of the quarks the theory is unitary also above
these energy scales.


title:
Spin $3/2$ Interacting Fields and Heavy Baryon Chiral Perturbation
  Theory

abstract:
  We analyze the consistency of the Chiral Lagrangian approach to the
description of the spin 3/2 interacting theory. We argue that to lowest order
in the 1/m expansion, the formalism leads to the appropriated constraints and
the theory is free of the so called ``off shell" ambiguities.


title: Parton Distributions in Nuclei: Overview and Prospect

abstract:
  We give a brief overview of nuclear parton distributions. First, the EMC
effect is discussed together with possible interpretations such as nuclear
binding and $Q^2$ rescaling. Next, we explain shadowing descriptions:
vector-meson-dominance-type and parton-recombination models. Nuclear dependence
of $Q^2$ evolution should be interesting in testing whether or not DGLAP
equations could be applied to nuclear structure functions. Status of nuclear
sea-quark and gluon distributions is discussed. The structure function $b_1$,
which will be measured at HERMES and possibly at ELFE, could shed light on a
new aspect of high-energy spin physics.


title: The $\pi\gamma$ transition form factor and the pion wave function

abstract:
  The pion wave function is discussed in the light of the recent CLEO data on
the pion gamma transition form factor. It turns out that the wave function is
close to the asymptotic form whereas wave functions strongly concentrated in
the end-point regions are disfavoured. Consequences for other exclusive
quantities, as for instance the pion's electromagnetic form factor, are also
discussed.


title: On the Theoretical Analysis of the Small $x$ Data in Recent HERA Papers

abstract:
  A number of internal inconsistencies, misleading conclusions and lack of
completeness in the analyses of the small $x$ deep inelastic data in recent
papers of HERA physicists, particularly in a very recent one by the H1
collaboration are pointed out. It is also shown that, when an analysis without
prejudice is carried over, the situation is very different from the one claimed
there in what respects checks of theoretical expectations.


title:
High Temperature Dimensional Reduction of the MSSM and other
  Multi-Scalar Models

abstract:
  Using dimensional reduction we construct an effective 3D theory of the
Minimal Supersymmetric Standard Model at finite temperature. The final
effective theory is obtained after three successive stages of integration out
of massive particles. We obtain the full 1-loop relation between the couplings
of the reduced theory and the underlying 4D couplings and masses. The procedure
is also applied to a general two Higgs doublet model and the Next to Minimal
Supersymmetric Standard Model.


title: Chiral Perturbation Theory, Large-N_c and the eta' Mass

abstract:
  Using chiral perturbation theory and the large-$N_c$ expansion, we obtain
expressions for the $\eta'$ mass and $\eta - \eta'$ mixing in terms of
low-energy chiral Lagrangian parameters. This is accomplished through an
intermediate step of `matching' the topological susceptibility in the
large-$N_c$ and chiral Lagrangian descriptions. By inserting the values of
well-measured parameters we obtain predictions involving the the second order
parameters $L_6,L_7$ and $L_8$. The prediction for $L_6$ is quite restrictive
even after allowing for $1/ N_c$ corrections.


title:
Implications of Electroweak Precision Data on Bounds on the Higgs-Boson
  Mass

abstract:
  Carefully analyzing the dependence of the bounds on the Higgs-boson mass
$\MH$ derived from the observables $\swbar^2(\LEP)$, $\swbar^2(\SLD)$, $\Gl$,
$\MW$, $\GT$, $\Gh$, as well as $\Rb$ and $\Rc$, and considering the
uncertainties in $\alpha(\MZ^2)$ and $\alpha_s(\MZ^2)$, we find that a stronger
bound than $40\GeV\lsim\MH\lsim 1\TeV$ at the $1\sigma$ level can hardly be
deduced at present, even if the experimental information on the top-quark mass
$\Mt$ from direct production is taken into account.


title: Comparison of CDF and D0 Inclusive Jet Cross-sections

abstract:
  The recently reported CDF and D0 inclusive jet cross-sections are compared,
using a uniform theoretical NLO QCD calculation to account for the different
kinematic coverages of the pseudo-rapidity variable in the two experiments. The
two data sets are found to be in good agreement. With a 2-3\% relative overall
normalization adjustment, the data sets appear to agree over the entire $E_t$
range, even without taking into account the other systematic errors.


title: Heavy-quark jets in hadronic collisions

abstract:
  We present a next-to-leading order QCD calculation of the production rates of
jets containing heavy quarks. This calculation is performed using the standard
Snowmass jet algorithm; it therefore allows a comparison with similar results
known at next-to-leading order for generic jets. As an application, we present
results for the inclusive transverse energy of charm and bottom jets at the
Tevatron collider, with a complete study of the dependence on the jet cone-size
and of the theoretical uncertainties.


title: The Partonic Structure of the Proton

abstract:
  We review the latest information that is available about the parton
distributions of the proton, paying particular attention to the determination
of the gluon. We briefly describe the various processes that have been
advocated to be a measure of the gluon. We discuss the importance of the gluon
to the description of the structure function F2 at small x, with emphasis on
the ln 1/x resummations.


title: Topcolor: A Dynamical Approach to Top Quark Mass Generation

abstract:
  In Topcolor theories the mass of the top quark is generated dynamically by
new strong interactions coupling to the third generation fermions. This leads
to potentially observable effects in flavor-changing neutral current processes
involving heavy flavored mesons, as well as in the production of heavy quarks
at high-energy colliders. Recent theoretical developments and potential
phenomenological constraints on these models are also briefly reviewed.


title: Matter-enhanced Three-flavor Oscillations and the Solar Neutrino Problem

abstract:
  We present a systematic analysis of the three-flavor
Mikheyev-Smirnov-Wolfenstein (MSW) oscillation solutions to the solar neutrino
problem, in the hypothesis that the two independent neutrino square mass
differences, $\delta m^2$ and $m^2$, are well separated: $\delta m^2 \ll m^2$.
At zeroth order in $\delta m^2/m^2$, the relevant variables for solar neutrinos
are $\delta m^2$ and two mixing angles, $\omega$ and $\phi$. We introduce new
graphical representations of the parameter space $(\delta
m^2,\,\omega,\,\phi)$, that prove useful both to analyze the properties of the
electron-neutrino survival probability and to present the results of the
analysis of solar neutrino data. We make a detailed comparison between the
theoretical predictions of the Bahcall--Pinsonneault standard solar model and
the current experimental results on solar neutrino rates, and discuss
thoroughly the MSW solutions found by spanning the whole three-flavor space
$(\delta m^2,\,\omega,\,\phi)$. The allowed regions can be radically different
from the usual ``small mixing'' and ``large mixing'' solutions, characteristic
of the usual two-generation MSW approach. We also discuss the link between
these results and the independent information on neutrino masses and mixings
coming from accelerator and reactor oscillation searches.


title: Measuring $\alpha_s(Q^2)$ in $\tau$ Decays

abstract:
  The decay rate of the $\tau$ lepton into hadrons of invariant mass smaller
than $Q\gg\Lambda_{\rm QCD}$ can be calculated in QCD using the OPE. Using
experimental data on the hadronic mass distribution, the running coupling
constant $\alpha_s(Q^2)$ is extracted in the range $0.85~\mbox{GeV}<Q<m_\tau$,
where its value changes by about a factor~2. At $Q=m_\tau$, the result is
$\alpha_s(m_\tau^2)=0.33\pm 0.03$, corresponding to $\alpha_s(m_Z^2)=0.119\pm
0.004$. The running of the coupling constant is in excellent agreement with the
QCD prediction based on the three-loop $\beta$-function.


title:
Prompt Photon Production in $\gamma \gamma$ Collisions and the Gluon
  Content of the Photon

abstract:
  We calculate the cross section for inclusive prompt photon production in
$\gamma\gamma$ collisions, i.e. the reaction $e^+e^-\to \gamma \gamma \to
\gamma X$, in next-to-leading order QCD. We show that at LEP2 energies this
cross section is measurable and is sensitive to the gluon distribution of the
photon, $g^{\gamma}$, which is currently very poorly constrained by data.


title: On the Asymptotic Behaviour of F_2(x,Q^2)

abstract:
  We discuss how the proton structure function F2 is described in the HERA
kinematic range by double asymptotic expressions for low x and large Q^2. From
a NLO double asymptotic approximation of recent data from the H1 experiment at
HERA we extract the strong coupling constant
alpha_S(M^2_Z)=0.113+/-0.002(stat)+/-0.007(syst). The additional theoretical
error can be as large as 0.007.


title:
Non-Equilibrium Dynamics of a Quench-Induced Phase Transition and
  Topological Defect Formation

abstract:
  We study the full out-of-thermal-equilibrium dynamics of a relativistic
classical scalar field through a symmetry breaking phase transition. In these
circumstances we determine the evolution of the ensemble averages of the
correlation length and topological defect densities. This clarifies many
aspects of the non-perturbative dynamics of fields in symmetry breaking phase
transitions and allows us to comment on a quantitative basis on the canonical
pictures for topological defect formation and evolution. We also compare these
results to those obtained from the field evolution in the Hartree approximation
or using the linearized theory. By doing so we conclude about the regimes of
validity of these approximations.


title: Prospects for detecting an $\eta_c'$ in two photon processes

abstract:
  We argue that an experimental search for an $\eta_c'$, the first radial
excitation of the $\eta_c(2980)$, may be carried out using the two photon
process $e^+e^- \to e^+e^- \gamma \gamma \ra e^+e^-\eta_c'$. We estimate the
partial width $\Gamma_{\gamma \gamma}(\eta_c')$ and the branching fraction
$B(\eta_c' \to h)$, where $h$ is an exclusive hadronic channel, and find that
for $h = K^o_s K^\pm \pi^\mp$ it may be possible to observe this state in two
photon collisions at CLEO-II.


title: Deep Inelastic Scattering and Light-Cone Wave Functions

abstract:
  In the framework of light-cone QCD sum rules, we study the valence quark
distribution function $q(x_B)$ of a pion for moderate $x_B$. The sum rule with
the leading twist-2 wave function gives $q(x_B)=\varphi_\pi(x_B)$. Twist-4 wave
functions give about 30\% for $x_B\sim 0.5$. It is shown that QCD sum rule
predictions, with the asymptotic pion wave function, are in good agreement with
experimental data. We found that a two-hump profile for the twist-2 wave
function leads to a valence quark disribution function that contradicts
experimental data.


title: Antimatter in Different Baryogenesis Scenarios

abstract:
  Possible mechanisms of abundant creation of antimatter in the universe are
reviewed. The necessary conditions for that are: baryonic charge
nonconservation, spontaneous breaking of charge symmetry or nonequilibrium
initial state, and the formation of appropriate initial conditions during
inflation. In this case the universe may be populated with domains, cells, or
even stellar size objects consisting of antimatter.


title:
Unified Description of Rapidity Gaps and Energy Flows in DIS Final
  States

abstract:
  We show that the `orthogonal' characteristics of the observed rapidity gaps
and large forward energy flows in deep inelastic scattering at HERA, can be
described within a single framework. Our Monte Carlo model is based on
perturbative QCD matrix elements and parton showers together with Lund string
model hadronization, but has in addition a new mechanism for soft colour
interactions which modifies the perturbative colour structure and thereby the
hadronization. Effects of perturbative multiparton emission are investigated
and the non-perturbative treatment of the proton remnant is discussed and
comparison to the observed transverse energy flow is made. We investigate the
resulting diffractive-like properties of the model; such as rapidity gap
events, $t$- and $M_X$-distributions and the diffractive structure function in
comparison to H1 data.


title: Two Topics in Particle-Antiparticle Mixing

abstract:
  This paper summarizes two experimental issues in the study of particle
antiparticle mixing. We propose a new method to extract the ratio
$|V_{ts}/V_{td}|^2$ from a measurement of $\Delta \Gamma/\Gamma$ for the $B_s$
meson. This method is experimentally more sensitive than the conventional
method for large values of $|V_{ts}|$ but depends on the accuracy of parton
level calculations. We then briefly discuss the implications of large CP
violation and final state interactions (FSI) in the experimental search for
$D^0-\bar{D}^0$ mixing. The work described here was carried out in
collaboration with S. Pakvasa.


title: Effective Theories of MSSM at High Temperature

abstract:
  We construct effective 3d field theories for the Minimal Supersymmetric
Standard Model, relevant for the thermodynamics of the cosmological electroweak
phase transition. The effective theories include a 3d theory for the bosonic
sector of the original 4d theory; a 3d two Higgs doublet model; and a 3d
SU(2)+Higgs model. The integrations are made at 1-loop level. In integrals
related to vacuum renormalization we take into account only quarks and squarks
of the third generation. Using existing non-perturbative lattice results for
the 3d SU(2)+Higgs model, we then derive infrared safe upper bounds for the
lightest Higgs boson mass required for successful baryogenesis at the
electroweak scale. The Higgs mass bounds turn out to be close to those
previously found with the effective potential, allowing baryogenesis if the
right-handed stop mass parameter $m_U^2$ is small. Finally we discuss the
effective theory relevant for $m_U^2$ very small, the most favourable case for
baryogenesis.


title: Broken Symmetries in the Early Universe

abstract:
  We give a brief review of recent results on symmetry nonrestoration at high
temperature.


title:
AROMA 2.2 - A Monte Carlo Generator for Heavy Flavour Events in $ep$
  Collisions

abstract:
  A program to simulate the production of heavy quarks through the boson-gluon
fusion process in $e^{\pm}p$ collisions is presented. The full electro\-weak
structure of the electron--gluon interaction is taken into account as well as
the masses of the produced heavy quarks. Higher order QCD radiation is treated
using initial and final state parton showers, and hadronization is performed
using the Lund string model. Physics and programming aspects are described in
this manual.