title: Determining the Gluonic Content of Isoscalar Mesons

abstract:
  We develop tools to determine the gluonic content of a resonance of known
mass, width and $J^{PC}$ from its branching fraction in radiative quarkonium
decays and production cross section in $\gamma \gamma$ collisions. We test the
procedures by applying them to known $q\bar{q}$ mesons, then analyze four
leading glueball candidates. We identify inconsistencies in data for $J/\psi
\to \gamma f_0(1500)$ and $J/\psi \to \gamma f_J(1710)$ whose resolution can
quantify their glueball status.When $\Gamma(f_0(1500) \to \gamma \gamma )$ and
$\Gamma(f_J(1710) \to \gamma \gamma)$ are known, the $n\bar{n}, s\bar{s},gg$
mixing angles can be determined. The enigmatic situation in 1400-1500 MeV
region of the isosinglet $0^{-+}$ sector is discussed.


title:
Photoproduction off Nuclei and Point-like Photon Interactions Part I:
  Cross Sections and Nuclear Shadowing

abstract:
  High energy photoproduction off nuclear targets is studied within the
Glauber-Gribov approximation. The photon is assumed to interact as a
$q\bar{q}$-system according to the Generalized Vector Dominance Model and as a
``bare photon'' in direct scattering processes with target nucleons. We
calculate total cross sections for interactions of photons with nuclei taking
into account coherence length effects and point-like interactions of the
photon. Results are compared to data on photon-nucleus cross sections, nuclear
shadowing, and quasi- elastic $\rho$-production. Extrapolations of cross
sections and of the shadowing behaviour to high energies are given.


title:
The interference in the reaction $e^+e^-\to\gamma\pi^+\pi^-$ and the
  search for the decay $\phi\to\gamma f_0\to\gamma\pi^+\pi^-$

abstract:
  We describe the interference between amplitudes $e^+e^- \to \rho \to
\gamma\pi^+\pi^-$ and $e^+e^- \to \phi \to \gamma f_0 \to \gamma\pi^+\pi^-$,
where $f_0$ meson is considered in the frameworks of the four-quark model and
the model of the scalar $K\bar K$ molecule. The general expressions for the
differential cross section with the radiative corrections and two angle cuts
are given. The interference patterns are obtained in the spectrum of the
differential cross section by the energy of the photon and in the full cross
section by the energy of the beams.


title: Can $B\to J/\psi K(K^*)$ decays be described by factorization ?

abstract:
  The new measurements of $B\to J/\psi K(K^*)$ decays by CDF and CLEO indicate
that the production ratio $R$ and the fraction of longitudinal polarization
$\Gamma_L/\Gamma$ are smaller than the previous results. In conjunction with
the new result of parity-odd transverse polarization in $B\to J/\psi K^*$, we
found a minimal modification to the factorization hypothesis: While the data of
$B\to J/\psi K^*$ can be accommodated in the factorization approach with
nonfactorizable terms $\chi_{A_1} = \chi_{A_2} = \chi_{V} \equiv \chi$ of order
15%, the result of $R$ measurement requires that the nonfactorizable effect
$\chi_{F_1}$ on $B\to J/\psi K$ be slightly larger than $\chi$. Therefore, the
effective parameter $a_2^{\rm eff}$ is not universal even for $B\to J/\psi
K(K^*)$ decays. We have generalized the considerations to $B\to \psi(2S)K(K^*)$
and $B_s\to J/\psi\phi$ and found that the predictions are in agreement with
currently available data.


title: Supersymmetric QCD corrections to the W-boson width

abstract:
  We calculate the one-loop supersymmetric QCD corrections to the width of the
$W$-boson. We find that these are of order $\sim {{ \alpha_s} \over {\pi}} {1
\over 20} { {M^2_W} \over {M_S^2}} \Gamma_{u {\bar d}}$, where $M_S$ is the
supersymmetry breaking scale and $ \Gamma_{u {\bar d}}$ the tree level hadronic
width for $W^+ \rightarrow u {\bar d} $. Due to the appearance of the
suppression factor $\sim {1 \over 20}$ these are at least two orders of
magnitude smaller than the standard QCD corrections $\sim {{ \alpha_s} \over
{\pi}} \Gamma_{u {\bar d}}$ and hence of the order of the two-loop electroweak
effects. Therefore supersymmetric QCD corrections will only be of relevance
once experiments reach that level of accuracy.


title: New representation of the two-loop crossed vertex function

abstract:
  We calculate the two-loop vertex function for the crossed topology, and for
arbitrary masses and external momenta. We derive a double integral
representation, suitable for a numerical evaluation by a Gaussian quadrature.
Real and imaginary parts of the diagram can be calculated separately.


title:
DIPSI: a Monte Carlo generator for elastic vector meson production in
  charged lepton-proton scattering

abstract:
  We present a Monte Carlo generator for exclusive vector meson production in
charged lepton-proton interactions, l+p --> l+p+V, based on a QCD leading
logarithm model calculation according to which the cross section for this
process is proportional to the square of the gluon momentum density in the
proton. The generator can be used for both fixed target and collider
kinematics. Each event is assigned a weight equal to its cross section, so that
the independent variables can be generated according to convenient
distributions, not necessarily identical to the physics ones.


title:
Prospects for a Measurement of $\alpha_s$ via Scaling Violations of
  Fragmentation Functions in Deeply Inelastic Scattering

abstract:
  The prospects for a determination of the strong coupling constant $\alpha_s$
via scaling violations of fragmentation functions in deeply inelastic
scattering are studied. The statistical error in the case of an integrated
luminosity of $250 pb^{-1}$, and the theoretical errors due to the various
parton density parametrizations and to the factorization scale dependence are
estimated.


title: Quark transverse momentum in hard scattering processes

abstract:
  The role of transverse momentum of quarks in semi-inclusive leptoproduction
will be discussed. It involves generalized distribution and fragmentation
functions which depend on both the longitudinal lightcone momentum fraction of
the quarks and on the transverse momentum. Constraints on these functions and
relations between them arise as a consequence of the QCD equation of motion for
the quark fields, Lorentz invariance and of C, P, and T invariance of the
strong interactions. Experimentally one has access to the functions for
instance in measurements of azimuthal asymmetries in hard processes.


title: Quark masses in Qiu's factorization procedure

abstract:
  We discuss a higher-twist factorization procedure of the hadron tensor in
deep inelastic scattering, proposed by Qiu, and extend it to include quark mass
terms. Its property that the hard scattering parts are electromagnetic gauge
invariant separately, is manifestly preserved. Using an auxiliary parton, a
so-called spurion, to generate the quark mass terms, a simple parton model
interpretation is also retained.


title:
Do the Profile Function singularities explain the high energy reflection
  of fermions in a phase transition?

abstract:
  We investigate the scope of a previous result concerning the behaviour of
fermions hitting a general wall caused by a first-order phase transition. The
wall profile function was considered to be analytic in the real axis. The
previous result is valid for analytic functions in the whole complex plane
except in certain isolated singularities located out of the real axis. A
non-analytic profile function in the real axis is studied in order to show the
validity of the result for any profile which can be put as a certain limit of a
function which verifies the latter. A new understanding of the high energy
behaviour of the quantum reflection caused by a sharp profile, as the step,
arises from that study.


title:
Inclusive neutrino and antineutrino processes and the problem of the
  spin of proton

abstract:
  The inclusive NC and CC neutrino(antineutrino)-nucleus scattering for the
case of a nucleus with isotopic spin equal to zero is considered. It is shown
that the measurement of the neutrino-antineutrino asymmetry at relatively small
energies could allow to obtain model-independent information about the
contribution of the axial strange current to the cross sections of the NC
processes.


title: Generic Current-Carrying Strings

abstract:
  We investigate the standard model in a cosmic string background and show that
the electroweak symmetry is partially restored. For a range of parameters the
electroweak Higgs field can wind in this region, producing an electroweak
string stabilised by the cosmic string background. In this case there are quark
and lepton zero modes that result in the string becoming superconducting at the
electroweak scale. If the electroweak Higgs field does not wind, there are no
zero modes, but there are fermion bound states. These bound states can also
carry a current.


title: Nucleon Decay in a Realistic SO(10) SUSY GUT

abstract:
  In this paper, we calculate neutron and proton decay rates and branching
ratios in a predictive SO(10) SUSY GUT which agrees well with low energy data.
We show that the nucleon lifetimes are consistent with the experimental bounds.
The nucleon decay rates are calculated using all one-loop chargino and gluino
dressed diagrams regardless of their chiral structure. We show that the
four-fermion operator $C_{jk} (u_R {d_j}_R)({d_k}_L {\nu_\tau}_L)$, commonly
neglected in previous nucleon decay calculations, not only contributes
significantly to nucleon decay, but, for many values of the initial GUT
parameters and for large $\tan\beta$, actually dominates the decay rate. As a
consequence, we find that $\tau_p/\tau_n$ is often substantially larger than
the prediction obtained in small $\tan\beta$ models. We also find that
gluino-dressed diagrams, often neglected in nucleon decay calculations,
contribute significantly to nucleon decay. In addition we find that the
branching ratios obtained from this realistic SO(10) SUSY GUT differ
significantly from the predictions obtained from ``generic" SU(5) SUSY GUTS.
Thus nucleon decay branching ratios, when observed, can be used to test
theories of fermion masses.


title: Color-Octet Contributions in the Associate J/psi+gamma Hadroproduction

abstract:
  Color-octet contributions to the associate J/psi+gamma hadroproduction are
studied in detail, and found to be negligible, compared to the ordinary
color-singlet contribution. Within the color-singlet model the J/psi+gamma
production in the leading order is possible only through gluon-gluon fusion
process. Therefore, the associate J/psi+gamma hadroproduction remains to be
useful as a clean channel to probe the gluon distribution inside proton, to
study heavy quarkonia production mechanism, and to find proton's spin
structure.


title: Time reversal odd fragmentation functions

abstract:
  The combination of transverse momentum and polarization effects in hard
scattering processes, e.g polarized deep-inelastic leptoproduction, results in
a rich variety of information on the hadronic structure. This information is
encoded in a correspondingly large number of functions depending on both,
longitudinal fractional momenta $x$ and transverse momenta $p_T$. Integration
over transverse momenta establishes the connection to the usual distribution
and fragmentation functions. Constraints from hermiticity and invariance under
parity operation induce some relations between different functions. One
specific aspect of the information on the hadronic structure is the appearance
of {\em time reversal odd} fragmentation functions due to the non-applicability
of time-reversal invariance for the hadronization of a quark. {\em T-odd}
fragmentation functions are experimentally accessible via the measurement of,
for instance, asymmetries in semi-inclusive leptoproduction.


title: The Quasi-Infra-Red Fixed Point at Higher Loops

abstract:
  We calculate the four-loop $\beta$-function for the generalised Wess-Zumino
model. We use the result and Pad\'e-Borel summation to discuss the domain of
attraction of the quasi-infra-red fixed point of the top-quark Yukawa coupling
in the supersymmetric standard model, and argue that the domain is in fact
substantial.


title: Rare B \to K^{(*)} \nu\bar\nu Decays at B Factories

abstract:
  We compute the branching fraction of the decays $B \to K \nu \bar\nu$ and $B
\to K^* \nu \bar\nu$ in the Standard Model. We also comment on the experimental
difficulties and procedures to detect such modes at B factories.


title: Simple GUTs

abstract:
  Together with some positive features, such as the constrained hypercharge
assignments, grandunification models typically have some unwelcome aspects,
mostly associated with the rich and peculiarly selected matter content. I
discuss some ideas which might help to interpret (part of) this apparent
complexity arising in grandunification in terms of simple structures. I also
point out that the conventional criteria used to establish fine tuning in
grandunified models should be modified if these models are viewed as effective
low-energy descriptions of a more fundamental theory.


title:
Probing Quartic Couplings Through Three Gauge Boson Production at an
  $e^+e^-$ Linear Collider

abstract:
  We explore the capability of a 500 or 1000 GeV $e^+e^-$ linear collider to
measure anomalous quartic gauge boson couplings. In the framework of a
non-linear effective Lagrangian with a custodial $SU)2)$ symmetry, there are
only two next-to-leading order operators which contribute to quartic, but not
to two- and three- gauge boson interactions. The limits on the coefficients of
these operators from present and future $e^+e^-$ colliders are compared with
those available from other sources.


title:
A solution to the puzzles of CP violation, neutrino oscillation, fermion
  masses and mixings in an SUSY GUT model with small $tan \beta$

abstract:
  CP violation, fermion masses and mixing angles including that of neutrinos
are studied in an SUSY SO(10)$\times \Delta(48) \times$ U(1) model with small
$tan \beta$. It is amazing that the model can provide a successful prediction
on twenty three observables by only using four parameters. The renormalization
group (RG) effects containing those above the GUT scale are considered. Fifteen
relations among the low energy parameters are found with nine of them free from
RG modifications. They could be tested directly by low energy experiments.


title:
Quantum-Mechanical Interference over Macroscopic Distances in the B^0
  B^0 bar System

abstract:
  We argue that the B^0 B^0 bar state generated in the decay of Upsilon(4S) is
well suited for performing tests of Einstein-Podolsky-Rosen correlations, i.e.,
quantum-mechanical interference effects over macroscopic distances. Using
measurements of the ratio R = (#like-sign dilepton events)/(#opposite-sign
dilepton events) and of the B_H - B_L mass difference we show that already
presently existing data strongly favour the contribution of the interference
term to R, as it is required by the rules of quantum mechanics.


title: Diffractive rho^0 photo- and leptoproduction at high energies

abstract:
  We discuss the elastic photo- and leptoproduction of rho^0-mesons from
nucleons at Q^2 < 1 GeV^2 as studied in recent experiments at HERA and FNAL. We
find that the mass distribution of the measured \pi^+\pi^- pairs is determined
to a large extent by the two-pion contribution to the photon spectral function
as given by the pion form factor. With rising Q^2 the rate of diffractive
events decreases and the \pi^+\pi^- mass distribution approaches a symmetric
shape.


title: On the Interpretation of the NA51 Experiment

abstract:
  We study the $p-n$ Drell-Yan asymmetry, recently measured by the NA51
collaboration, and conclude that the value quoted by their experiment only sets
a lower limit on the asymmetry of the proton sea. In particular, we notice that
charge symmetry breaking between the proton and the neutron may produce
corrections which should be taken into account.


title: Asymmetric Quark/Antiquark Hadronization in e+e- Annihilation

abstract:
  We point out that the fragmentation of a strange quark into nucleons versus
antinucleons is not necessarily identical $D_{p/s}(z,Q^2) \neq D_{\bar
p/s}(z,Q^2)$, even though the perturbative contributions from gluon splitting
and evolution are $p \leftrightarrow \bar p$ symmetric. The observation of such
asymmetries in the hadronization of strange and other heavy quarks can provide
insight into the nonperturbative mechanisms underlying jet fragmentation in
QCD.


title: Prospects for B-Physics in the Next Decade

abstract:
  In these lectures I review what has been learned from studies of b-quark
decays, including semileptonic decays ($V_{ub}$ and $V_{cb}$),
$B^o-\overline{B}^o$ mixing and rare B decays. Then a discussion on CP
violation follows, which leads to a summary of plans for future experiments and
what is expected to be learned from them. (Presented at NATO Advanced Study
Institute on Techniques and Concepts of High Energy Physics, Virgin Islands,
July 1996.)


title: Probing CP Violation via Top Polarization at NLC

abstract:
  Possible $CP$-violation in top-quark couplings is discussed. It is shown that
the lepton-energy distributions in $e^+ e^- \to t\bar{t} \to \ell^+\ell^-X /
\ell^\pm X$ at next linear colliders (NLC) could give us useful information for
this study. The statistical significance of $CP$-violating-parameter
determination is estimated.


title:
Hadronic Final States in e+e- Interactions and their Relevance to Cosmic
  Rays

abstract:
  Elementary particle physics using beams from accelerators and cosmic rays are
compared. In particular, recent results on the energy evolution of charged
particle multiplicities, the differences between quark and gluon jets, and
scaling violations observed in electron-positron annihilation are described.


title:
Multiparticle Aspects of e+e- Interactions at an Energy of 133 GeV at
  LEP

abstract:
  Electron-positron annihilations at an average center-of-mass energy of 133
GeV from the four LEP-experiments are presented. This includes in particular
the total cross-section and multiplicities, thrust, rapidity and transverse
momentum distributions as well as inclusive particle spectra.


title:
Di-Boson production at Hadron Colliders with General 3 Gauge Boson
  Couplings. Analytic Expressions of Helicity Amplitudes and Cross-Section

abstract:
  We discuss the tests of general Three Gauge Boson Vertices (TGV) through
bosonic pair production at present and future hadron colliders. All bosonic
final states are reviewed via the tree level quark-antiquark annihilation
sub-process. The full analytic expressions of the helicity amplitudes and
cross-sections are given. These expressions should be useful in any attempt to
disentangle the effects of the most general non standard $WWV (V=\gamma,Z)$
vertices including 14 free parameters. We investigate the sensitivity of the
invariant mass and transverse momentum distributions to the full set of
anomalous couplings including final state polarization structures. We
particularly consider these features at the projected CERN Large Hadron
Collider (LHC) energy scale.


title: Virtual Meson Cloud of the Nucleon and Intrinsic Strangeness and Charm

abstract:
  We have applied the Meson Cloud Model (MCM) to calculate the charm and
strange antiquark distribution in the nucleon. The resulting distribution, in
the case of charm, is very similar to the intrinsic charm momentum distribution
in the nucleon. This seems to corroborate the hypothesis that the intrinsic
charm is in the cloud and, at the same time, explains why other calculations
with the MCM involving strange quark distributions fail in reproducing the low
x region data. From the intrinsic strange distribution in the nucleon we have
extracted the strangeness radius of the nucleon, which is in agreement with
other meson cloud calculations.


title:
Can Long Range Anomalous Neutrino Interactions Account for the Measured
  Tritium Beta Decay Spectrum ?

abstract:
  Recent experimental searches for neutrino mass in tritium beta decay yield a
negative value for the mass-squared of the electron neutrino. If this effect is
genuine, then it is hard to understand it using conventional particle physics
ideas as embodied in the standard model or its simple extensions that have been
widely discussed. We consider the possibility that there is a hidden anomalous
long range interaction of neutrinos that is responsible for this effect and
study the phenomenological consistency of this idea. We also discuss how such
interactions may arise in extensions of the standard model.


title:
QED Penguin Contributions To Isospin Splittings of Heavy-Light Quark
  Systems

abstract:
  Recent experiments show that the isospin-violating mass splitting of the B
mesons is very small, but the best fits with a QCD sum rule analysis give a
splitting of at least 1.0 MeV. The isospin-violating mass splittings of the
charmed mesons, on the other hand, are in agreement with experiment. In this
letter we show that the inclusion of 2$^{nd}$ kind QED penguin diagrams can
account for this discrepancy within the errors in the QCD sum rule method.


title: Stop decays in SUSY-QCD

abstract:
  The partial widths are determined for stop decays to top quarks and gluinos,
and gluino decays to stop particles and top quarks (depending on the masses of
the particles involved). The widths are calculated including one-loop SUSY-QCD
corrections. The radiative corrections for these strong-interaction decays are
compared with the SUSY-QCD corrections for electroweak stop decays to quarks
and neutralinos/charginos and top-quark decays to stops and neutralinos.


title: Possible tests of the "strangeness" of the nucleon

abstract:
  The NC and CC scattering of neutrino(antineutrino) on protons and nuclei with
isotopic spin equal to zero is considered. It is shown that the measurement of
the neutrino-antineutrino asymmetry in these processes could allow to obtain
model-independent information about the contribution of the axial strange
current to the cross sections of the NC processes.


title:
Prospects for Measuring Delta G from Jets at HERA with Polarized Protons
  and Electrons

abstract:
  The measurement of the polarized gluon distribution function Delta G(x) from
photon-gluon fusion processes in electron-proton deep inelastic scattering
producing two jets has been investigated. The study is based on the MEPJET and
PEPSI simulation programs. The size of the expected spin asymmetry and
corresponding statistical uncertainties for a possible measurement with
polarized beams of electrons and protons at HERA have been estimated. The
results show that the asymmetry can reach a few percent, and is not washed out
by hadronization and higher order processes.


title:
Hadronic Spin Dependence and the Use of Coulomb-Nuclear Interference as
  a Polarimeter

abstract:
  Coulomb-nuclear interference in the single transverse spin asymmetry A_N is
often considered as a possible absolute polarimeter for proton beams. The main
uncertainty in this is the unknown hadronic spin-flip amplitude. This
uncertainty is analyzed here in the context of the challenge of a 5%
polarization measurement at RHIC. Possible constraints on the spin-flip
amplitude from measurements of the differential cross-section and the double
transverse spin asymmetry A_{NN} are discussed.


title: MSW-like Enhancements without Matter

abstract:
  We study the effects of a scalar field, coupled only to neutrinos, on
oscillations among weak interaction current eigenstates. The effect of a real
scalar field appears as effective masses for the neutrino mass eigenstates, the
same for $\nbar$ as for $\n$. Under some conditions, this can lead to a
vanishing of $\delta m^2$, giving rise to MSW-like effects. We discuss some
examples and show that it is possible to resolve the apparent discrepancy in
spectra required by r-process nucleosynthesis in the mantles of supernovae and
by Solar neutrino solutions.


title: Effects of Anomalous Couplings of Quarks on Prompt Photon Production

abstract:
  Prompt photon production is sensitive to the anomalous couplings of gluons to
quarks, because it is mainly produced by quark-gluon scattering. We will
examine the effects of the anomalous chromoelectric and chromomagnetic dipole
moment couplings of quarks on prompt photon production. Using the data
collected by CDF and D0 at the Fermilab Tevatron we put a bound on these
anomalous couplings. We also estimate the sensitivity of various future high
energy collider experiments to these anomalous couplings.


title:
A Big Bang Nucleosynthesis Likelihood Analysis of the Baryon-to-Photon
  Ratio and the Number of Light Particle Degrees of Freedom

abstract:
  We extend the model-independent likelihood analysis of big bang
nucleosynthesis (BBN) based on He4 and Li7 to allow for numbers of degrees of
freedom which differ from the standard model value characterized by $N_\nu =
3$. We use the two-dimensional likelihood functions to simultaneously constrain
the baryon-to-photon ratio and the number of light neutrinos. The upper limit
thus obtained is $N_\nu < 4.0$ (at 95% C.L.). We also consider the consequences
if recent observations of deuterium in high-redshift QSO absorption-line
systems (QSOALS) are confirmed.


title: Lecture on a Z' Coupled to Beauty and Truth

abstract:
  By extending the standard gauge group to $SU(3)_c \times SU(2)_L \times
U(1)_Y \times U(1)_X$ with $X$ charges carried only by the third family we
accommodate the LEP measurement of $R_b$ and predict a potentially measurable
discrepancy in $A_{FB}^{b}$ in $e^+e^-$ scattering and that $D^0 \bar D^0$
mixing may be near its experimental limit. The uniqueness of our model is that
the Z' couplings are generation-dependent and hence explicitly violate the GIM
mechanism, but can nevertheless be naturally consistent with FCNC constraints.
Direct detection of this Z' is possible but challenging.


title: Cosmological Structure Formation With and Without Hot Dark Matter

abstract:
  Cold + Hot Dark Matter (CHDM) is perhaps the best theory of cosmic structure
formation {\it if} the cosmological matter density is near critical (i.e.,
$\Omega_0 \approx 1$) and {\it if} the expansion rate is not too large (i.e. $h
\equiv H_0/(100 \kmsMpc) \lsim 0.6$). I discuss CHDM together with its chief
competitor among CDM variants, low-$\Omega_0$ CDM with a cosmological constant
(\lcdm). \lcdm\ with $\Omega_0 \sim 0.3$ has the possible virtue of allowing a
higher expansion rate $H_0$ for a given cosmic age $t_0$, but the defect of
predicting too much fluctuation power on small scales. Also, except for the
$H_0-t_0$ problem, there is not a shred of evidence in favor of a nonzero
cosmological constant, only increasingly stringent observational upper bounds
on it. CHDM has less power on small scales, in good agreement with data,
although it remains to be seen whether it predicts early enough galaxy
formation to be compatible with the latest high-redshift data. CHDM has the
advantage among $\Omega=1$ CDM-type models of requiring little or no tilt,
which appears to be an advantage in fitting recent small-angle cosmic microwave
background anisotropy data. The presence of a hot component that clusters less
than cold dark matter lowers the effective $\Omega_0$ that would be measured on
small scales, which appears to be in accord with observations, and it may also
avoid the discrepancy between the high central density of dark matter halos
from CDM simulations compared to evidence from rotation curves of dwarf spiral
galaxies.


title: u^{c}d^{c}d^{c}-Based Affleck-Dine Baryogenesis

abstract:
  We consider the possibility of a successful Affleck-Dine mechanism along the
u^c d^c d^c direction in R-parity symmetric extensions of the minimal
supersymmetric Standard Model (MSSM) which contain a gauge singlet superfield
phi. Such gauge singlets commonly occur in extensions of the MSSM, for example
in models which seek to account for neutrino masses. We consider a two scalar
Affleck-Dine mechanism, with the flat direction stabilized by a
non-renormalizible superpotential term of the form (lambda/M) phi udd ~
(lambda/M) phi psi^3, where psi corresponds to the gauge non-singlet flat
direction. We give approximate solutions of the scalar field equations of
motion which describe the evolution of the condensates and show that the final
baryon asymmetry in this case is suppressed relative to that expected from the
conventional single scalar Affleck-Dine mechanism, based on a superpotential
term of the form (lambda/(4M)) psi^4, by a factor
(m_{s}/(m_{phi}+m_{s}))^(1/2), where m_{s} is the soft supersymmetry breaking
scalar mass and m_{phi} is the supersymmetric phi mass. It is possible for the
model to generate a baryon asymmetry even in the limit of unbroken B-L, so long
as the gauge singlet condensate doesn't decay until after anomalous electroweak
B+L violation is out of equilibrium following the electroweak phase transition.
This condition is generally satisfied if all Dirac neutrino masses are less
than around 10keV. This class of Affleck-Dine models can, in principle,be
experimentally ruled out, for example by the observation of a Dirac mass for
the mu or tau neutrino significantly larger than around 10keV together with a
mostly Higgsino LSP.


title: Searching for supersymmetry in rare B decays

abstract:
  We quantify the ability of B-Factories to observe supersymmetric
contributions to the rare decays B -> X_s \gamma and B -> X_s l+ l-. A global
fit to the Wilson coefficients which contribute to these decays is performed
from Monte Carlo generated data on B(B -> X_s \gamma) and the kinematic
distributions associated with the final state lepton pair in B -> X_s l+ l-.
This fit is then compared to supersymmetric predictions. Evaluation of the
Wilson coefficients is carried out with several different patterns of the
superpartner spectrum. We find that the B-Factories will be able to probe
regions of the SUSY parameter space not accessible to LEPII, the Tevatron, and
perhaps the LHC. We also employ the recent NLO calculation of the matrix
elements for B -> X_s \gamma and find the bound mH+ > 300 GeV in
two-Higgs-doublet models using present data.


title:
Nucleosynthesis bounds on small Dirac neutrino masses due to chiral
  symmetry breaking

abstract:
  We consider nucleosynthesis constraints on models which use chiral symmetry
breaking as a basis for understanding very small Dirac neutrino masses. We show
that present big-bang nucleosynthesis constraints impose a well-defined upper
bound of 0.1eV on the neutrino masses. This bound may become several orders of
magnitude more stringent in the future as our understanding of the
observational constraints on nucleosynthesis improves. We discuss the
phenomenological implications for neutrino dark matter, the solar neutrino
problem and the atmospheric neutrino deficit.


title:
An Analysis of \pi\pi-Scattering Phase Shift and Existence of
  \sigma(555) particle

abstract:
  In most of the Nambu:Jona-Lasinio(NJL)-type models, realizing the hidden
chiral symmetry, the existence of a scalar particle \sigma is needed with a
mass m_\sigma=2 m_q, as a partner of the Nambu-Goldstone boson \pi. However,
the results of many analyses on \pi\pi phase-shift thus far made have been
negative for its existence. In this paper we re-analyze the phase-shift,
applying a new method, the interfering amplitude method, which treats the
T-matrix directly and describes multi-resonances in conformity with the
unitarity. As a result, the existence of \sigma has been strongly suggested
from the behavior of the \pi\pi-->\pi\pi phase shift between the \pi\pi- and
the KK- thresholds, with mass = 553.3 +- 0.5_{st} MeV and width= 242.6 +-
1.2_{st} MeV. The most crucial point in our analysis is the introduction of a
negative background phase, possibly reflecting a ``repulsive core" in \pi\pi
interactions. The properties of f_0(980) are also investigated from data
including those over the KK threshold. Its mass is obtained as 993.2 +-
6.5_{st} +- 6.9_{sys} MeV. Its width is about a hundred MeV, although this
depends largely on the treatment of the elasticity and the \pi\pi-->KK phase
shift, both of which may have large experimental uncertainties.


title: Property of \sigma(600) and Chiral Symmetry

abstract:
  The iso-singlet scalar resonance \sigma(600), found in the recent \pi\pi
phase shift analysis, is pointed out to have the properties of the \sigma meson
in the \sigma model. The role of the \lambda\phi^4 interaction as a source of
the ``background phase", which was essential there, is also discussed.


title: Jets and High-Et Phenomena

abstract:
  The working group on jets and high-Et phenomena of the Future physics at HERA
Workshop studied subjects ranging from next-to-leading order (NLO) corrections
in deeply inelastic scattering (DIS) and photoproduction with the corresponding
determinations of physical quantities, to the physics of instanton-induced
processes, where a novel non-perturbative manifestation of QCD could be
observed. Other centres of interest were the physics of the forward direction,
the tuning of event generators and the development of a new generator which
includes a consistent treatment of the small- and large-$x$ QCD evolution. The
recommendations of the working group concerning detector upgrades and machine
luminosity are summarized.


title: The role of chiral loops in $\eta\to\pi^0\pi^0\gamma\gamma$

abstract:
  We consider the rare decay $\eta\to\pi^0\pi^0\gamma\gamma$ and calculate the
non-resonant contribution to the amplitude to one loop in Chiral Perturbation
Theory. We display our result as both a diphoton energy spectrum and a partial
decay rate as a function of the photon energy cut. It turns out that the
one-loop correction can be numerically very important and could be detected, at
sufficiently large center-of-mass photon energies, from a measurement of the
partial decay width.


title:
A simple approach to describe hadron production rates in $e^+ e^-$
  annihilation

abstract:
  We show that, based on the idea of string fragmentation, the production rates
of light flavored mesons and baryons originating from fragmentation can be
described by the spin, the binding energy of the particle, and a strangeness
suppression factor. Apart from a normalization factor, $e^+ e^-$ data at
different center-of-mass energies can be described simultaneously. Applying to
the heavy flavor production, we find that our predictions are in good agreement
with data.


title: QCD Aspects of Polarized Hard Scattering Processes

abstract:
  I give an overview of what our present knowledge of QCD predicts and does not
predict for polarized hard scattering. For experimental programs, a big issue
is how much further we can expect our theoretical understanding of QCD to
improve.


title: Strangeness in the Nucleon on the Light-Cone

abstract:
  Strange matrix elements of the nucleon are calculated within the light-cone
formulation of the meson cloud model. The $Q^2$ dependence of the strange
vector and axial vector form factors is computed, and the strangeness radius
and magnetic moment extracted, both of which are found to be very small and
slightly negative. Within the same framework one finds a small but non-zero
excess of the antistrange distribution over the strange at large $x$. Kaon
loops are unlikely, however, to be the source of a large polarized strange
quark distribution.


title:
QCD dipole predictions for quark singlet, gluon and $F_L/F_T$
  distributions at HERA

abstract:
  In this contribution we apply the QCD dipole picture combined with
$k_T$-factorization to get predictions for deep-inelastic scattering on an
onium. Assuming renormalization-group factorization, we get predictions for the
$F_2, F_G$ and $R= F_L/F_T$ proton structure functions. We obtain a
three-parameter fit of the 1994 H1 data in the low-$x_{bj}$, moderate-$Q^2$
range. $F_G/F_2$ and $R$ are then predicted without any additionnal parameter.
The BFKL dynamics contained in the dipole model is shown to provide a relevant
model in describing the HERA data. The prediction for $F_2$ and $F_G$ are
compatible with next-to-leading order DGLAP analysis. By contrast, $R$ is
expected to be much lower at small $x_{bj}$.


title: Rare B Decays in the Standard Model

abstract:
  We discuss the electromagnetic-penguin-dominated radiative B decays $B \to
X_s + \gamma, ~B^{\pm (0)} \to K^{*\pm (0)} + \gamma$, and $B_s \to \phi +
\gamma$ in the context of the standard model (SM) and their
Cabibbo-Kobayashi-Maskawa (CKM)-suppressed counterparts, $B \to X_d + \gamma$,
$B^\pm \to \rho^\pm + \gamma, ~B^{0} \to (\rho^{0}, \omega) + \gamma$, and $B_s
\to K^{* 0} + \gamma$, using QCD sum rules for the exclusive decays. The
importance of these decays in determining the parameters of the CKM matrix is
emphasized. The semileptonic decays $B \to X_s \ell^+ \ell^-$ are also
discussed in the context of the SM and their role in determining the Wilson
coefficients of the effective theory is stressed. Comparison with the existing
measurements are made and SM-based predictions for a large number of rare B
decays are presented.


title:
Renormalization Scheme Consistent Structure Functions, Including Leading
  ln (1/x) Terms

abstract:
  We present calculations of structure functions using a renormalization scheme
consistent expansion which is leading order in both ln(1/x) and \alpha_s(Q^2).
There is no factorization scheme dependence, and the ``physical anomalous
dimensions'' of Catani naturally appear. A relationship between the small x
forms of the inputs F_2(x,Q_0^2) and F_L(x,Q_0^2) is predicted. Analysis of a
very wide range of data for F_2(x,Q^2) is performed, and a very good global fit
obtained. The prediction for F_L(x,Q^2) produced using this method is smaller
than the usual NLO in \alpha_s(Q^2) predictions for F_L(x,Q^2), and different
in shape.


title: Electroweak Phase Transition and Neutrino Masses

abstract:
  The presently observed cosmological baryon asymmetry has been finally
determined at the time of the electroweak phase transition, when baryon and
lepton number violating interactions fell out of thermal equilibrium. We
discuss the thermodynamics of the phase transition based on the free energy of
the SU(2) Higgs model at finite temperature, which has been studied in
perturbation theory and lattice simulations. The results suggest that the
baryon asymmetry has been generated by lepton number violating interactions in
the symmetric phase of the standard model, i.e., at temperatures above the
critical temperature of the electroweak transition. The observed value of the
baryon asymmetry, $n_B/s \sim 10^{-10}$, is naturally obtained in an extension
of the standard model with right-handed neutrinos where $B-L$ is broken at the
unification scale $\Lambda_{GUT}}\sim 10^{16}$ GeV. The corresponding pattern
of masses and mixings of the light neutrinos $\nu_e$, $\nu_\mu$ and $\nu_\tau$
is briefly described.


title: Nonperturbative Flow Equations and Low--Energy QCD

abstract:
  We review the formalism of the effective average action in quantum field
theory which corresponds to a coarse grained free energy in statistical
mechanics. The associated exact renormalization group equation and possible
nonperturbative approximations for its solution are discussed. This is applied
to QCD where one observes the consecutive emergence of mesonic bound states and
spontaneous chiral symmetry breaking as the coarse graining scale is lowered.
We finally present a study of the phenomenological importance of
non--renormalizable terms in the effective linear meson model.


title:
Will at least one of the Higgs bosons of the next-to-minimal
  supersymmetric extension of the Standard Model be observable at LEP2 or the
  LHC?

abstract:
  We demonstrate that there are regions of parameter space in the
next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield)
supersymmetric extension of the SM for which none of the Higgs bosons are
observable either at LEP2 with $\sqrt{s}=192 GeV$ and an integrated luminosity
of $L=1000 inverse pb$ or at the LHC with $L=600 inverse fb$.


title: Quantum solitons at strong coupling

abstract:
  We examine the effect of one loop quantum corrections on the formation of
nontopological solitons in a strongly coupled scalar-fermionic Yukawa theory.
The exact one fermion loop contribution is incorporated by using a nonlocal
method to correct the local derivative expansion approximation (DE) of the
effective action. As the Yukawa coupling is increased we find that the nonlocal
corrections play an increasingly important role. The corrections cause the
scalar field to increase in depth while maintaining its size. This increases
the energy of the bag configuration, but this is compensated for by more
tightly bound fermionic states with lower energy. In contrast to the
semi-classical picture without quantum corrections, the binding energy is
small, and the total energy scales directly with the Yukawa coupling. This
confirms the qualitative behavior found in earlier work using the second order
DE, although the quantitative solutions differ.


title: Time-Variations of Solar Neutrino Signals

abstract:
  The most popular solutions of the solar neutrino problem which assume massive
neutrinos predict varying with time signals in the solar neutrino detectors.
The variations represent a distinctive feature of these solutions and do not
depend on the theoretically predicted total flux of neutrinos from the Sun. The
sensitivity of SuperKamiokande and SNO to day-night variations due to
regeneration in the Earth is estimated.


title: Perturbative Unification and Low Energy Precision Data

abstract:
  More precise unification predictions require going beyond the lowest order,
including 2-loop running of the couplings and a correct treatment of threshold
effects. Here we revised two different approaches to deal with light
thresholds, based on different choices of the renormalization scheme, \bar{MS}
and effective couplings. We show the equivalence of both approaches in making
predictions when thresholds are taking properly into account.


title: Precision Top Mass Measurements vs. Yukawa Unification Predictions

abstract:
  How accurately should the top quark mass be measured in order to test
theoretical predictions? A possible answer is presented within a particular
theoretical framework, that of top-bottom-tau Yukawa unification in a
supersymmetric SO(10) grand unified theory. Yukawa unification, and the
uncertainties in its $m_t$ prediction, are introduced by analogy to gauge
unification and the uncertainties in the predictions of $sin^2\theta_W$ or
$\alpha_3(m_Z)$. There are two sources of uncertainty in this framework:
``removable'' uncertainties due to physics at the electroweak and
supersymmetry-breaking scales, and ``irremovable'' ones from physics at and
above the unification scale. The latter are precisely the model-dependent
effects which would shed light on the nature of the unified model, so they may
be regarded as a (model-dependent) part of the prediction rather than as
uncertainties. The removable sources are estimated first using current
experimental bounds, and then using plausible guesses for the bounds that may
be available within roughly a decade: they are not likely to be reduced below
roughly $\pm 1 GeV$. That is the level at which such unified theories will be
testable against future experimental determinations of the top mass.


title: Spin Effects in Diffractive Deep Inelastic Scattering

abstract:
  We discuss the contribution of diffractive $Q \bar Q$ production to the
longitudinal double-spin asymmetry in polarized deep--inelastic $lp$
scattering. We show the strong dependence of the $A_{ll}$ asymmetry on the
pomeron spin structure.


title: Effects of Pomeron Coupling in Diffractive Reactions

abstract:
  The diffractive 2-jet production reactions in the proton-proton and
lepton-proton processes are discussed. It is shown that they may be very
suitable for studying the properties of the pomeron couplings with quarks and
hadrons in future polarized experiments at HERA, especially for HERA-$\vec N$
project.


title: High order corrections to the Renormalon

abstract:
  The high order corrections to renormalon are considered. Each new type of
insertions into the renormalon chain of graphs generates the correction to the
asymptotics of perturbation theory of the order of $\sim 1$. However, this
series of corrections to the asymptotics is not the asymptotic one (i.e. the
$m$-th correction does not grow like $m!$). The summation of these corrections
for UV renormalon may change the asymptotics by factor $N^\delta$. For the
traditional IR renormalon the $m$-th correction diverges like $(-2)^m$.
However, this divergency has no infrared origin and may be removed by proper
redefinition of IR renormalon. On the other hand for IR renormalons in hadronic
event shapes one should naturally expect these multi-loop contributions to
decrease like $(-2)^{-m}$. Some problems expected upon reaching the best
accuracy of perturbative QCD are also discussed.


title:
Nonequilibrium Dynamics of Symmetry Breaking in Lambda Phi^4 Field
  Theory

abstract:
  The time evolution of O(N) symmetric lambda Phi^4 scalar field theory is
studied in the large N limit. In this limit the <Phi> mean field and two-point
correlation function <Phi Phi> evolve together as a self-consistent closed
Hamiltonian system, characterized by a Gaussian density matrix. The static part
of the effective Hamiltonian defines the True Effective Potential U_eff for
configurations far from thermal equilibrium. Numerically solving the time
evolution equations for energy densities corresponding to a quench in the
unstable spinodal region, we find results quite different from what might be
inferred from the equilibrium free energy ``effective'' potential F. Typical
time evolutions show effectively irreversible energy flow from the coherent
mean fields to the quantum fluctuating modes, due to the creation of massless
Goldstone bosons near threshold. The plasma frequency and collisionless damping
rate of the mean fields are calculated in terms of the particle number density
by a linear response analysis and compared with the numerical results.
Dephasing of the fluctuations leads also to the growth of an effective entropy
and the transition from quantum to classical behavior of the ensemble. In
addition to casting some light on fundamental issues of nonequilibrium quantum
statistical mechanics, the general framework presented in this work may be
applied to a study of the dynamics of second order phase transitions in a wide
variety of Landau-Ginsburg systems described by a scalar order parameter.


title:
Charmed Quark and J/Psi Photoproduction in the Semihard Approach of OCD
  at HERA Energies

abstract:
  We compare our theoretical results for charmed quark and J/Psi -
photoproduction cross sections obtained in the semihard approach of QCD with H1
and ZEUS experimental data.


title: Bose-Einstein Correlations - A Program for the 21th. century

abstract:
  It is argued that Bose-Einstein correlations constitute one of the most
important and characteristic effects of strong interactions. The progress made
in our understanding of this phenomenon is reviewed and a program for future
research in this field is formulated.


title: Soft particle production and QCD coherence

abstract:
  We discuss the behaviour of the energy spectrum of particles in jets near the
limit of small momenta of a few hundred MeV. In QCD parton cascades the soft
gluons are coherently emitted from all faster partons in the jet and their
production rate is predicted to scale. The observed charged and identified
particle spectra follow this behaviour surprisingly well supporting of the
hypothesis of the Local Parton Hadron Duality (LPHD) for this extreme limit.
Further tests of this perturbative approach are discussed.


title: Electroweak Event Generators for LEP2 and the Linear Collider

abstract:
  I discuss the state of the art and outline direction for research in event
generation for electroweak physics at LEP2 and e+e- Linear Colliders.


title:
HIGLU and HDECAY: Programs for Higgs Boson Production at the LHC and
  Higgs Boson Decay Widths

abstract:
  The total cross section for Higgs boson production via the dominant gluon
fusion mechanism including NLO [two-loop] QCD corrections can be calculated
numerically with the program HIGLU. The QCD corrections are included for
arbitrary Higgs and quark masses and increase the cross section at the LHC by
up to a factor of 2. The source code HIGLU provides the evaluation of the
production of the Standard Model [SM] Higgs boson as well as the neutral Higgs
bosons of the minimal supersymmetric extension [MSSM]. The program HDECAY
determines the decay widths and branching ratios of the Higgs bosons within the
SM and the MSSM, including the dominant higher-order corrections. The latter
are dominated by QCD corrections and two-loop corrections to the couplings and
Higgs masses of the MSSM. The program includes all decay modes with branching
ratios larger than $10^{-4}$. Moreover, below-threshold decays with off-shell
top quarks, gauge and Higgs bosons are implemented. In addition the program is
able to calculate the branching ratios of the MSSM Higgs bosons into
supersymmetric particles, which can be dominant.


title:
Optimized-Variational Quark Mass Expansion and Dynamical Chiral Symmetry
  Breakdown

abstract:
  A recently proposed variational mass expansion approach to dynamical chiral
symmetry breakdown is reviewed. We briefly explain how a specific integral
ansatz over the analytically continued, arbitrary Lagrangian mass parameter,
resums the usual variational mass expansion (``delta-expansion".) The
construction is then generalized to obtain non-perturbative expressions for the
order parameters of the $SU(n_f)_L \times SU(n_f)_R$ breakdown ($n_f =$ 2 or
3), in QCD. Emphasis is put on some general aspects as well as possible
limitations of this approach.


title: Symmetry Restoration in Hot SUSY

abstract:
  It is by now well known that symmetries may be broken at high temperature.
However,in renormalizable supersymmetric theories any internal symmetry gets
always restored. In nonrenormalizable theories the situation is far less
simple. We review here some recent work which seems to indicate that
renormalizability is not essential for the restoration of internal symmetries
in supersymmetry.


title: Field theory near the critical temperature

abstract:
  Field theory at nonvanishing temperature beyond perturbation theory is
discussed for the $N$-component $O(N)$-symmetric scalar theory. We compute the
effective potential directly in three dimensions using an exact evolution
equation for an effective action with an infrared cutoff. A suitable truncation
is solved numerically. We obtain a detailed quantitative picture of the scaling
form of the equation of state in the vicinity of the critical temperature of a
second order phase transition.


title: Coarse graining and first order phase transitions

abstract:
  We discuss the dependence of the coarse grained free energy and the classical
interface tension on the coarse graining scale $k$. A stable range appears only
if the renormalized dimensionless couplings at the critical temperature are
small. This gives a quantitative criterion for the validity of computations
within Langer's theory of spontaneous bubble nucleation.


title:
Relic Abundances and Detection Rates of Neutralinos in String-Inpired
  Supergravity Models

abstract:
  We calculate ``relic abundances'' and ``detection rates'' of the neutralino
(LSP) in string-inspired supergravity models with ``dilaton-moduli'' induced
supersymmetry breaking. In particular we investigate ``universal'' scenarios
for the soft-supersymmetry breaking terms from Calabi-Yau compactifications, as
well as from the dilaton-dominated limit. ``Non-universal'' scenarios from
orbifold string theory are also incorporated into the analysis. In all cases,
in the cosmologically interesting region, we find $m_{LSP}\geq 50$ GeV and
direct-detection rates in the range O($10^{-3}$ events/(Kg day)) - O($10^{-4}$
events/(Kg day)). ``Indirect-detection'' rates from LSPs captured in the Sun
are also calculated.


title: Signatures of Dynamical Symmetry Breaking at Tevatron Upgrade and LHC

abstract:
  We study the phenomenology of a strongly interacting electroweak symmetry
breaking sector in which the physics is dominated by spin one resonances.
Specifically we will consider an effective description of dynamical symmetry
breaking based on a particular model which passes all the low-energy precision
tests and gives clear signals at LHC but also at Tevatron Upgrade.


title:
Penguin Zoology in $B\to\pi\pi$ and the Extraction of the CKM Angle
  $\alpha$

abstract:
  We reanalyze the decay $B_d\to\pi^+\pi^-$ without assuming dominance of QCD
penguins with internal top-quark exchanges. In that case the weak phase of the
$\bar b \to\bar d$ QCD penguin amplitude is not related in a simple way to the
CKM angle $\beta$. Nevertheless it is still possible to extract the CKM angle
$\alpha$ in a transparent and almost model-independent way from the
time-dependent CP-violating asymmetry of the transition $B_d\to\pi^+\pi^-$.
Aside from that CP asymmetry this approach needs as an input only amplitudes of
decays with branching ratios of order $10^{-5}$ and will thus be well within
reach at future $B$-factories.


title:
Signals for the Minimal Gauge-mediated Supersymmetry Breaking Model at
  the Fermilab Tevatron Collider

abstract:
  We investigate the experimental implications of the minimal gauge-mediated
low energy supersymmetry breaking (GMLESB) model for Fermilab Tevatron collider
experiments. We map out the regions of parameter space of this model that have
already been excluded by collider searches and by limits on $b\to s\gamma$. We
use ISAJET to compute the cross sections for a variety of topological
signatures which include photons in assocation with multiple leptons, jets and
missing transverse energy. The reach in the parameter $\Lambda$, which fixes
the scale of sparticle masses, is estimated to be $\sim 60$, 100 and 135 TeV
for Tevatron integrated luminosities of 0.1, 2 and 25 fb$^{-1}$, respectively.
The largest signals occur in photon(s) plus lepton(s) plus multi-jet channels;
jet-free channels containing just photons plus leptons occur at much smaller
rates, at least within this minimal framework.


title: Further Analysis on \sigma-particle Properties

abstract:
  In a previous work, we have reanalyzed the I=0 S-wave \pi\pi-scattering
phase-shift through a new method of Interfering Breit-Wigner amplitudes, and
have shown the existence of a light scalar, \sigma particle, accompanied by a
negative "repulsive core"-type background phase-shift, whose origin may have
some correspondence to a ``compensating'' \pi\pi contact interaction. In this
work we make further analysis on the phase shift under KKbar threshold from the
same standpoint, to determine precise values of \sigma mass and width, so far
as present experimental data are concerned.


title:
Electromagnetic Corrections for Pions and Kaons : Masses and
  Polarizabilities

abstract:
  The unknown constants in Chiral Perturbation Theory needed for an all orders
analysis of the polarizabilities and electromagnetic corrections to the masses
of the pseudo-Goldstone bosons are estimated at leading order in $1/N_c$. We
organize the calculation in an $1/N_c$-expansion and separate long- and
short-distance physics contributions by introducing an Euclidean cut-off. The
long-distance part is evaluated using the ENJL model and the short-distance
part using perturbative QCD and factorization. We obtain very good matching
between both.
  We then include these estimates in a full Chiral Perturbation Theory
calculation to order $e^2$ $p^2$ for the masses and $p^6$ for the
polarizabilities. For the electromagnetic corrections to the masses, we confirm
a large violation of Dashen's theorem getting a more precise value for this
violation. We make comparison with earlier related work. Some phenomenological
consequences are discussed too.


title: Equivalence of Covariant and Light-Front Perturbation Theory

abstract:
  Light-Front Field Theory (LFFT) is a good candidate to describe bound states.
In LFFT covariance is non-manifest. Burkardt and Langnau claim that, even for
scattering amplitudes, rotational invariance is broken. We will take a
different path of obtaining rules for light-front time-ordered diagrams.
Covariance depends on the choice of a regulator $\alpha$. We need to apply some
regularisation scheme to render physical amplitudes finite. This is done by
applying minus regularisation. In this process all ambiguities related to the
regulator $\alpha$ are removed. Therefore there is equivalence between the
perturbative expansions of covariant and LFFT.


title:
Next to Leading Order QCD Corrections to Polarized $\Lambda$ Production
  in DIS

abstract:
  We calculate next to leading order QCD corrections to semi-inclusive
polarized deep inelastic scattering and $e^+e^-$ annihilation cross sections
for processes where the polarization of the identified final-state hadron can
also be determined. Using dimensional regularization and the HVBM prescription
for the $\gamma_5$ matrix, we compute corrections for different spin-dependent
observables, both in the $\overline{MS}$ and $\overline{MS_p}$ factorization
schemes, and analyse their structure. In addition to the well known corrections
to polarized parton distributions, we also present those for final-state
polarized fracture functions and polarized fragmentation functions, in a
consistent factorization scheme.


title: The Heavy Quark Expansion of QCD

abstract:
  These lectures contain an elementary introduction to heavy quark symmetry and
the heavy quark expansion. Applications such as the expansion of heavy meson
decay constants and the treatment of inclusive and exclusive semileptonic $B$
decays are included. Heavy hadron production via nonperturbative fragmentation
processes is also discussed.


title: NLO Quarkonium Production in Hadronic Collisions

abstract:
  We present some preliminary results on the next-to-leading order calculation
in QCD of quarkonium production cross sections in hadronic collisions. We will
show that the NLO total cross sections for $P$-wave states produced at high
energy are not reliable, due to the appearance of very large and negative
contributions. We also discuss some issues related to the structure of final
states in colour-octet production and to high-p_T fragmentation.


title: Minijets in ultrarelativistic heavy ion collisions at RHIC and LHC

abstract:
  Recent results on minijet production in nuclear collisions at the RHIC and
LHC energies are reviewed. Initial conditions of the QGP at $\tau=0.1$ fm$/c$,
especially parton chemistry, thermalization and net baryon number-to-entropy
ratio are discussed. Also, contribution of minijets from a hard BFKL-pomeron
ladder will be estimated.


title: Electroweak Theory Confronting Precision Data

abstract:
  We review the empirical evidence for the validity of the Standard Electroweak
Theory in nature. The experimental data are interpreted in terms of an
effective Lagrangian for Z physics, allowing for potential sources of SU(2)
violation and containing the predictions of the Standard Electroweak Theory as
a special case. Particular emphasis is put on discriminating loop corrections
due to fermion-loop vector-boson propagator corrections on the one hand, from
corrections depending on the non-Abelian structure and the Higgs sector on the
other hand. Results from recently obtained fits of the Higgs-boson mass are
reported, yielding M_H < 550GeV [800GeV] at 95% C.L. based on the input of
swbar^2(LEP+SLD)=0.23165+-0.00024 [swbar^2(LEP)=0.23200 +-0.00027]. With
respect to LEP2, it is emphasized that first direct experimental evidence for
non-zero non-Abelian couplings among the vector bosons can be obtained even
with restricted e+e- luminosity.


title: Sum-Rule Results on Exclusive Decays of Heavy Mesons

abstract:
  We review QCD sum rule applications to hadronic matrix elements of exclusive
$B$ and $D$ decays. Results are presented for the form factors $f^+$ and $F_0$
of $B \rightarrow \pi$ and $D\rightarrow \pi$ transitions. The predictions are
used to compute the width of $D^* \rightarrow D \pi$, and to extract the CKM
parameter $V_{ub}$ from the measured $B \rightarrow \pi e \nu$ width.
Furthermore, we comment on weak annihilation in $B \rightarrow \rho \gamma$, as
well as on the radiative decays $D \rightarrow \rho \gamma$, $D \rightarrow K^*
\gamma$, and $B \rightarrow \mu \nu \gamma$.


title: Probing Non-standard Top Couplings Using spin-correlation

abstract:
  Top spin correlation has been shown to be nontrivial in hadronic top-pair
production, and can be realized by the asymmetries of the decay products of the
top quark and antiquark. We show in this work that the top spin correlation is
a sensitive probe to the anomalous top-quark couplings beyond the standard
model. Specifically, we look at the anomalous chromomagnetic and chromoelectric
dipole moments, as well as a right-handed component in the weak decay of the
top quark. We found a few measurable asymmetries formed by the decay products
of the top-quark pair that vary in accord with the spin correlation.


title: Hunting for the Remaining Spin in the Nucleon

abstract:
  This talk consists of four parts. In part one, I give an elementary
discussion on constructing a Lorentz-invariant spin sum rule for the nucleon.
In part two, I discuss a gauge-dependent spin sum rule, explore its relation
with the polarized gluon distribution, and introduce the complete evolution
equation for the spin structure. In part three, I consider a gauge-invariant
spin sum rule and the related evolution equation. The solution of the equation
motivates the possibility that half of the nucleon spin may be carried by
gluons at low energy scales. In the final part, I discuss deeply-virtual
Compton scattering as a possible way to measure the canonical orbital angular
momentum of quarks in the nucleon.


title: One-Loop Amplitudes for e^+ e^- to q-bar q Q-bar Q

abstract:
  We present the one-loop helicity amplitudes for processes involving a vector
boson V (V=W,Z, or gamma^*) and four massless quarks, 0 to V q-bar q Q-bar Q,
where V couples to a massless lepton pair. These amplitudes are required for
next-to-leading order O(alpha_s^3) numerical programs for four-jet production
at e^+ e^- colliders, for W, Z or Drell-Yan production in association with two
jets at hadron colliders, and for three-jet production in deeply inelastic
scattering experiments. We obtained the amplitudes presented here by using
their analytic properties to constrain their form.


title:
Electroproduction of vector mesons off nuclei at ELFE: exact solution
  for color transparency

abstract:
  A multichannel evolution equation is developed for the density matrix
describing a hadronic wave packet produced by a virtual photon and propagation
through a nuclear matter. This approach is dual to the quark-gluon
representation, incorporates the effects of coherence and formation times and
gives an exact solution for color transparency problem at any photon energy. We
propose a procedure of data analysis, which provides an unambiguous way of
detection of a color transparency signal even at medium energies.


title:
Determining Color-Octet psi-Production Matrix Elements from gamma p and
  e p Processes

abstract:
  We calculated, within the NRQCD factorization formalism, the leading
color-octet contributions to psi production in photon-nucleon and
electron-nucleon collisions. The expressions obtained depend on the NRQCD
matrix elements <O^{psi}_8(^1S_0)> and <O^{psi}_8(^3P_J)>. These matrix
elements can be determined by fitting to experimental data. The color-octet
contribution to psi photoproduction is in the forward region of phase space,
where there may be large corrections to the NRQCD result from higher twist
terms. As to psi leptoproduction we point out that the theoretical
uncertainties plaguing the photoproduction calculation vanish in the large
momentum transfer limit. In this region of phase space the NRQCD formalism
should be valid, making psi leptoproduction an ideal laboratory for testing the
theory.


title:
Using Final State Gluons as Probes of Anomalous Top Quark Couplings at
  the NLC

abstract:
  The rate and corresponding gluon jet energy distribution for the process
$e^+e^- \to t\bar tg$ are sensitive to the presence of anomalous dipole-like
couplings of the top to the photon and $Z$ at the production vertex as well as
to the gluon itself. For sizeable anomalous couplings substantial deviations in
the shape and magnitude of the gluon spectrum from the expectations of the
Standard Model are anticipated. We explore the capability of the Next Linear
Collider to either discover or place bounds on these types of top quark
couplings through measurements of the gluon energy distribution. The resulting
constraints are found to be quite complementary to those obtained using other
techniques. [To appear in the Proceedings of the 1996 DPF/DPB Summer Study on
New Directions for High Energy Physics-Snowmass96, Snowmass, CO, 25 June-12
July, 1996.]


title: Light adjoint scalars and unification at the string scale

abstract:
  Following the suggestion of Bachas, Fabre and Yanagida (BFY), we analyze the
gauge coupling unification at the two-loop order, in a supersymmetric scenario
where scalars belonging to the adjoint representations contribute to the
evolution of the couplings from intermediate scales onward, and the unification
scale is pushed towards the string scale. Thereafter, we compare the masses of
these adjoint scalars to the scale at which the hidden sector gauge coupling
reaches the non-perturbative limit at the two-loop order for various possible
hidden sector gauge groups motivated by the the conjecture of BFY that the
masses of these adjoint scalars are related to gaugino condensation. We also
compute the predictions for the top and bottom quark masses in this scenario
and compare them with those of MSSM. The predicted bottom mass improves in the
BFY scenario for smaller values of $\alpha_s$.


title: Distinguishing Among Models of Strong W_L W_L Scattering at the LHC

abstract:
  Using a multi-channel analysis of W_L W_L scattering signals, I study the
LHC's ability to distinguish among various models of strongly interacting
electroweak symmetry breaking sectors.


title: Composite two-Higgs model with dynamical CP-violation

abstract:
  Quark models with four-fermion interaction including derivatives of fields
are exploited as prototypes for composite-Higgs extensions of the Standard
Model. In the non-trivial case of two- and four-derivative insertions the
dynamical breaking of chiral symmetry occurs in two channels, giving rise to
two composite Higgs doublets. For special configuration of four-fermion
coupling constants the dynamical CP-violation in the Higgs sector appears as a
result of complexity of two v.e.v. for Higgs doublets. In this scenario the
second Higgs doublet is regarded as a radial excitation of the first one.


title: Trilinear anomalous gauge couplings and non-standard fermionic couplings

abstract:
  In this paper we do an analysis of the reaction $e^+e^-\to W^+W^-$ for
various options of the Next Linear Colliders (NLC), by considering the
possibility of deviations from the Standard Model induced by anomalous
trilinear vector boson couplings and non-standard fermionic couplings. We show
that there are strong correlations among these parameters. By studying the
high-energy behaviour of the helicity amplitudes we show that the error made in
linearizing the cross-section in the anomalous and non-standard couplings
increases with the square of the center of mass energy. We consider also the
option of longitudinally polarized electron beams by showing that, in this
case, the restrictions on the anomalous and non-standard parameters are greatly
enhanced.


title:
Spin asymmetries from Non Standard Physics with polarized proton beams
  at RHIC

abstract:
  A new handed interaction between quarks could be at the origin of some small
parity violating effects in the inclusive production of one-jet in polarized
$pp$ collisions. This interaction could originate from compositeness or from
the presence of a new massive vector boson. The measurement of such asymmetries
could be performed within a few years by using the RHIC collider as a polarized
proton-proton collider.


title:
T864 (MiniMax): A Search for Disoriented Chiral Condensate at the
  Fermilab Collider

abstract:
  A small test/experiment has been performed at the Fermilab Collider to
measure charged particle and photon multiplicities in the forward direction,
$\eta \approx 4.1$. The primary goal is to search for disoriented chiral
condensate (DCC). The experiment and analysis methods are described, and
preliminary results of the DCC search are presented.


title:
Theory of Small $x$ Deep Inelastic Scattering NLO Evaluations, and low
  $Q^2$ Analysis

abstract:
  We calculate structure functions at small $x$ both under the assumption of a
hard singularity (a power behaviour $x^{-\lambda}, \lambda$ positive, for
$x\rightarrow 0$) or that of a soft-Pomeron dominated behaviour, also called
double scaling limit, for the singlet component. A full next to leading order
(NLO) analysis is carried for the functions $F_2, F_{\rm Glue}$ and the
longitudinal one $F_L$ in $ep$ scattering, and for $x F_3$ in neutrino
scattering. The results of the calculations are compared with data (HERA) in
the range $x\leq 0.032, 10 gev^2\leq Q^2\leq 1 500 gev^2$. We get reasonable
fits, with a chi-squared/d.o.f.$\sim 2$, for both assumptions, but none of them
gives a fully satisfactory description. The results improve substantially if
combining a soft and a hard component; in this case it is even possible to
extend the analysis, phenomenologically, to small values of $Q^2$, $0.31
gev^2\leq Q^2\leq 8.5 gev^2$, and in the $x$ range $6\times10^{-6}\lsim x \lsim
0.04$, with the same hard plus soft Pomeron hypothesis by assuming a saturating
expression for the strong coupling,
$\tilde{\alpha}_s(Q^2)=4\pi/\beta_0\log[(Q^2+\Lambda_{eff}^2)/\Lambda_{eff}^2]$
The description for low $Q^2$ implies self-consistent values for the parameters
in the exponents of $x$. One gets, for the Regge intercepts,
$\alpha_{\rho}(0)=0.48$ and $\alpha_P(0)=1.470$ [$\lambda=0.470$], in uncanny
agreement with other determinations of these parameters, in particular the
results of the large $Q^2$ fits. The fit to is so good that we may look (at
large $Q^2$) for signals of a "triple Pomeron" vertex; some evidence is found.


title: $\psi'$ Polarization due to Color-Octet Quarkonia Production

abstract:
  We calculated the polarization of \psi' due to gg \to Q\bar{Q}[^3P_J^(8)]g
\to \psi^\lambda color-octet quarkonia production. We find that at low
transverse momenta the \psi' is unpolarized due to the contributions
proportional to the L=S=0 and L=S=1 color-octet matrix elements. As p_\perp
increases, the \psi' mesons become 100% polarized, as predicted by
fragmentation calculations. Polarization due to lowest order color-singlet
production is also considered, which qualitatively has a similar shape to the
color-octet production.


title: Discovering New Interactions at Colliders

abstract:
  We summarize results of the 1996 Snowmass workshop on future prospects for
discovering dynamical electroweak symmetry breaking, compositeness, and
anomalous couplings of quarks at colliders. We present the mass reach of the
Tevatron to a color singlet or octet technirho, and to a topgluon or topcolor
Z' from topcolor assisted technicolor. We explore the sensitivity of the
Tevatron, LHC, NLC, and VLHC to contact interactions and excited fermions.
Finally we investigate the possibility of seeing anomalous couplings of quarks
at the Tevatron and LHC.


title:
TeV Right-handed Neutrinos and the Flavor-symmetry-improved Seesaw
  Mechanism

abstract:
  Horizontal flavor symmetries can drastically suppress Dirac neutrino masses
well below those of the corresponding charged leptons. We show that models can
be constructed where the light neutrino mass eigenvalues are small enough to
give the MSW solution to the solar neutrino problem, with a right-handed
neutrino scale no larger than a TeV. We present a model of this type where the
right-handed neutrino scale is generated by the spontaneous breakdown of gauged
U(1)$_{B-L}$, in a radiative breaking scenario driven by the right-handed
neutrino Yukawa couplings. The model allows for a solution to the $\mu$
problem, and predicts the existence of a $Z'$ boson within the reach of the LHC
or the Tevatron.


title:
Baryon Magnetic Moments and Axial Coupling Constants with Relativistic
  and Exchange Current Effects

abstract:
  The large relativistic corrections to the constituent quark current operators
improve the predictions for the axial couplings of the baryons, but worsen
those for their magnetic moments. The exchange current corrections that are
associated with flavor and spin dependent hyperfine interactions between the
quarks with a form suggested by pseudoscalar meson exchange can compensate the
relativistic corrections to the baryon magnetic moments. This is demonstrated
by a calculation of the magnetic moments of the non-strange and strange baryons
using wave functions and exchange current operators, which correspond to a
recent phenomenological spin- and flavor dependent interquark interaction model
with a linear confining interaction, which yields a spectrum close to the
empirical one. The possibility that part of the flavor and spin dependent
interaction could be due to vector and axial-vector exchange is explored.


title: Heavy-Quark Effective Theory

abstract:
  We give an introduction to the heavy-quark effective theory and the $1/m_Q$
expansion, which provide the modern framework for a systematic,
model-independent description of the properties and decays of hadrons
containing a heavy quark. We discuss the applications of these concepts to
spectroscopy and to the weak decays of $B$ mesons.


title: QCD dipole prediction for DIS and diffractive structure functions

abstract:
  The $F_{2}$, $F_{G}$, $R=F_{L}/F_{T}$ proton structure functions are derived
in the QCD dipole picture of BFKL dynamics. We get a three parameter fit
describing the 1994 H1 proton structure function $F_{2}$ data in the low $x$,
moderate $Q^{2}$ range. Without any additional parameter, the gluon density and
the longitudinal structure functions are predicted.The diffractive dissociation
processes are also discussed, and a new prediction for the proton diffractive
structure function is obtained.


title: Single Spin Asymmetries in Inclusive Hadron Production

abstract:
  We consider a general formalism, previously developed to describe single spin
asymmetries (SSA) in inclusive particle production at moderately large $p_T$ in
hadron-hadron high-energy processes. In this approach SSA can originate from
non perturbative, universal, quark distribution analyzing powers, provided the
quark intrinsic motion is taken into account. A fit of the available data on
$p^\uparrow p \to \pi X$ fixes simplified phenomenological expressions of these
quark analyzing powers for the dominant (at large $x_F$) $u$ and $d$ quark
contributions. We use the results of the fit as input to provide a possible
scenario for SSA in a number of interesting processes (e.g. $p p \to \gamma X$,
$p p \to K X$) for which experimental results are or will soon be available.


title: Spin Measurements in lp -> hX Deep Inelastic Scattering

abstract:
  The production of hadrons in polarized lepton-nucleon deep inelastic
scattering is discussed. The helicity density matrix of the hadron is computed
within the QCD hard scattering formalism and its elements are shown to yield
information on the spin structure of the nucleon and the spin dependence of the
quark fragmentation process. The case of $\rho$ vector mesons is considered in
more detail and estimates are given.


title:
Natural suppression of d=5 operator induced proton decay in
  supersymmetric grand unified theories

abstract:
  The proton decay in supersymmetric (SUSY) Grand Unified Theories (GUTs),
where the special mechanism provides the natural suppression of the dimension 5
($d=5$) operators, was studied. Due to this mechanism, $d=5$ operator induced
proton decay takes place only through the mixing of light generation fermions
with those from third generation and crucially depends on the structure of
fermion mass matrices. We show that in general proton decay is strongly
suppressed relative to the standard SUSY GUT situation and for wide class of
fermion mass matrices the SUSY parameter space practically has no restrictions.


title: Probing the exchanged object(s) in diffractive scattering

abstract:
  The reaction mechanisms of the following proton diffractive scattering
processes are studied and compared with one another: $\gamma^* p\to Vp,\gamma^*
p\to Xp, pp\to (\Lambda K^+)p$ and $pA\to \Lambda K^+A$ (Here, $\gamma^*$
stands for the space-like photon in inelastic electron-proton scattering, $V$
for the vector mesons $\rho,\omega,\phi,J/\psi$, and $A$ for a target nucleus.)
It is shown that, by taking parity, and C--parity conservation into account,
the existing data for these reactions strongly suggest the following: A
considerable part of the objects exchanged between projectile and target in the
above-mentioned processes are virtual quark-antiquark pairs in color-singlet
states with $J^{PC}=0^{-+}$, $I^G=0^+$, where $J$ stands for total angular
momentum, $I$ for isospin, $P$, $C$ and $G$ stand for parity, C-parity and
G-parity respectively. Such quark-antiquark pairs are created by soft-gluon
interactions. New experiments are suggested; and predictions for such
experiments are made.


title: Lattice Gauge Theory for QCD

abstract:
  These lectures provide an introduction to lattice methods for nonperturbative
studies of Quantum Chromodynamics.
  Lecture 1 (Ch. 2): Basic techniques for QCD and results for hadron
spectroscopy using the simplest discretizations;
  lecture 2 (Ch. 3): ``improved actions''--what they are and how well they work
  lecture 3 (Ch. 4): SLAC physics from the lattice: structure functions, the
mass of the glueball, heavy quarks and $\alpha_s(M_Z)$, and $B-\bar B$ mixing.


title:
QCD Description of Particle Spectra up to LEP-1.5 Energies and the
  Running of $\alpha_s$

abstract:
  Recent results on the energy spectra in QCD jets are reported. Within the
Modified Leading Logarithmic Approximation (MLLA) and the Local Parton Hadron
Duality (LPHD) model one finds a very good description of the $e^+e^-$ data
from the lowest up to the LEP 1.5 energies. A model with fixed $\alpha_s$ can
be excluded, already in certain finite energy intervals. The fits also
extrapolate smoothly into the region of small particle energies, in particular,
the data follow a scaling prediction for the low energy limit derived from the
colour coherence of the soft gluon emission.


title:
Implications of $\mu\nu \gamma \gamma$ Production on Precision
  Measurement of the W Mass

abstract:
  The process $p \bar p \rightarrow \mu^- \bar \nu \gamma \gamma$ is calculated
including finite lepton mass effects. Implications for precision measurements
of the $W$ mass at the Tevatron are discussed.


title: How Large Is the $^7{Be}$ Neutrino Flux from the Sun ?

abstract:
  On the basis of present solar neutrino observations and relaxing the
constraints from solar models it is possible that most (or nearly all) of the
flux of electron neutrinos detected comes from electron capture in $^7{Be}$.
These solutions arise from neutrino oscillations in which $\nu_e$ $-$
$\nu_\tau$ mixing suppresses high energy $\nu_e$ and $\nu_e - \nu_\mu$ mixing
suppresses low energy $\nu_e$ as qualitatively suggested from some SO(10) grand
unified models. The importance of future observations is emphasized.


title: Quark States Near a Threshold

abstract:
  We reduce the problem of many-channel hadron scattering at nonrelativistic
energies to calculations on the scale of a few fermis. Having thus disentangled
kinematics from interior quark dynamics, we study their interplay when a quark
state occurs near a hadronic threshold. Characteristic parameters, such as the
observed peak width, the decay width, and the shape of a cross-section itself
are highly affected by the threshold. A general pole-form expression for the
S-matrix in an arbitrary background is given, and the pole structure of S is
examined. We show that at a hadronic threshold two poles in S are generally
important. We also classify the S-matrix pole structure considering an example
where nonsingular coupled channels are closed at the threshold. The framework
of our paper is the P-matrix formalism, which is reviewed and extended for use
together with conventional methods of computing quark-gluon dynamics. Results
and applications are illustrated for the doubly strange two-baryon system, the
detailed analysis of which we postpone till our forthcoming paper.


title: Out of Equilibrium Dynamics of an Inflationary Phase Transition

abstract:
  We study the non-linear dynamics of an inflationary phase transition in a
quartically self coupled inflaton model within the framework of a de Sitter
background. Large N and Hartree non-perturbative approximations combined with
non-equilibrium field theory methods are used to study the self-consistent time
evolution including backreaction effects. We find that when the system cools
down from an initial temperature T_i > T_c to below T_c with the initial value
of the zero mode of the inflaton phi(0) << m lambda^{-1/4}, the dynamics is
determined by the growth of long-wavelength quantum fluctuations. For phi(0) >>
m lambda^{-1/4} the dynamics is determined by the evolution of the classical
zero mode. In the regime where spinodal quantum fluctuations give the most
important contribution to the non-equilibrium dynamics, we find that they
modify the equation of state providing a graceful exit from the inflationary
stage. Inflation ends through this new mechanism at a time scale t_s >=
[H/m^2]ln[lambda^{-1}] which for H >= m and very weak coupling allows over one
hundred e-folds during the de Sitter phase. Spatially correlated domains grow
to be of horizon-size and quantum fluctuations ``freeze-out'' for times t> t_s.


title:
Leptoquark pair production at the Fermilab Tevatron: Signal and
  backgrounds

abstract:
  We perform a Monte-Carlo simulation of scalar leptoquark pair production at
the Tevatron (energy =1.8 TeV and luminosity =100 pb^{-1}) with ISAJET. We also
investigate the dominant sources of Standard Model background: Z*jj, ZZ
production and heavy quark top-antitop. We find that the top-antitop background
is the most important except near the Z pole where the Z*jj background is
peaked. We also evaluate the signal-to-background ratio and find a discovery
reach of 130 GeV (170 GeV) for a branching ratio of B(LQ-> eq)=0.5 (B=1).


title: Deep Inelastic Physics with H1

abstract:
  A summary is presented of deep inelastic physics results obtained by the H1
collaboration during its first three years of experimentation at the
electron-proton collider HERA.


title:
Nonequilibrium Neutrino Oscillations in the Early Universe with an
  Inverted Neutrino-Mass Hierarchy

abstract:
  The annihilation of electron-positron pairs around one second after the big
bang distorts the Fermi-Dirac spectrum of neutrino energies. We determine the
distortions assuming neutrino mixing with an inverted neutrino-mass hierarchy.
Nonequilibrium thermodynamics, the Boltzmann equation, and numerical
integration are used to achieve the results. The various types of neutrino
behavior are established as a function of masses and mixing angles.


title: Lattice study of classical inflaton decay

abstract:
  We study numerically the decay of the inflaton by solving the full non-linear
equations of motion on the lattice. We confirm that parametric resonance is
effective in transferring energy from the inflaton to a scalar field as long as
the self-interactions of the second field are very small. However, in the very
broad resonance case (q>>1) the decay rate is limited by scatterings, which
significantly slows down the decay. We also find that the inflaton cannot decay
via parametric resonance into a scalar field with moderate self-interactions.
This means that the preheating stage may be completely absent in many natural
inflationary models.


title: Dimensional Regularization in Quarkonium Calculations

abstract:
  Dimensional regularization is incompatible with the standard covariant
projection methods that are used to calculate the short-distance coefficients
in inclusive heavy quarkonium production and annihilation rates. A new method
is developed that allows dimensional regularization to be used consistently to
regularize the infrared and ultraviolet divergences that arise in these
perturbative calculations. We illustrate the method by calculating the leading
color-octet terms and the leading color-singlet terms in the gluon
fragmentation functions for arbitrary quarkonium states. We resolve a
discrepancy between two previous calculations of the gluon fragmentation
functions for the spin-triplet P-wave quarkonium states.


title: Nucleon Strangeness and Unitarity

abstract:
  The strange-quark vector current form factors of the nucleon are analyzed
within the framework of dispersion relations. Particular attention is paid to
contributions made by $K\bar{K}$ intermediate states to the form factor
spectral functions. It is shown that, when the $K\bar{K}\to N\bar{N}$ amplitude
is evaluated in the Born approximation, the $K\bar{K}$ contributions are
identical to those arising from a one-loop calculation and entail a serious
violation of unitarity. The mean square strangeness radius and magnetic moment
are evaluated by imposing unitarity bounds on the kaon-nucleon partial wave
amplitudes. The impact of including the kaon's form factor in the dispersion
integrals is also evaluated.


title: Estimating Vacuum Tunneling Rates

abstract:
  We show that in Euclidean field theories that have bounce solutions, the
bounce with the least action is the global minimum of the action in an open
space of field configurations. A rigorous upper bound on the minimal bounce
action can therefore be obtained by finite numerical methods. This sets a lower
bound on the tunneling rate which, fortunately, is often the more interesting
and useful bound. We introduce a notion of reduction which allows this bound to
be computed with less effort by reducing complicated field theories to simpler
ones.


title: A Separate SU(2) for the Third Family: Topflavor

abstract:
  We consider the extended electroweak gauge group SU(2)_1 \times SU(2)_2
\times U(1)_Y where the first and second families of fermions couple to SU(2)_1
while the third family couples to SU(2)_2. Bounds based an precision
electroweak observables and heavy gauge boson searches are placed on the new
parameters of the theory. The extra gauge bosons can be as light as about a TeV
and can be discovered at future colliders such as the NLC and LHC for a wide
range of the parameter space. FCNC interactions are also considered.


title:
Baryogenesis During Reheating in Natural Inflation and Comments on
  Spontaneous Baryogenesis

abstract:
  We calculate the baryon asymmetry created by the decay of a pseudo
Nambu-Goldstone boson whose interactions violate baryon number conservation.
Our results are in disagreement with previous results in the original
spontaneous baryogenesis models for the asymmetry produced by the decay of an
oscillating scalar field with B number violating derivative couplings; we find
that the net baryon number density is proportional to $\th_i^3$, where $\th_i$
is the amplitude of the PNGB-field in natural inflation at the onset of
reheating. We also discuss our disagreement with the interpretation of
$\dot\theta$ as an effective chemical potential for baryon number in
spontaneous baryogenesis models. While our calculation of the asymmetry is
carried out in the context of natural inflation our approach is generally valid
for baryogenesis models using decaying classical fields. In the Appendices, we
include a complete derivation of the number density of particles produced by
the decay of a classical scalar field; this number density is proportional to
the integral over momenta of the one pair production amplitude.


title:
Improving the equivalent-photon approximation in electron--positron
  collisions

abstract:
  The validity of the equivalent-photon approximation for two-photon processes
in electron--positron collisions is critically examined. Commonly used forms to
describe hadronic two-photon production are shown to lead to sizeable errors.
An improved two-photon luminosity function is presented, which includes
beyond-leading-logarithmic effects and scalar-photon contributions. Comparisons
of various approximate expressions with the exact calculation in the case of
the total hadronic cross section are given. Furthermore, effects of the poorly
known low-Q2 behaviour of the virtual hadronic cross sections are discussed.


title: Single spin asymmetries in DIS

abstract:
  We consider possible mechanisms for single spin asymmetries in inclusive Deep
Inelastic Scattering (DIS) processes with unpolarized leptons and transversely
polarized nucleons. Tests for the effects of non-zero $\bfk_\perp$, for the
properties of spin dependent quark fragmentations and for quark helicity
conservation are suggested.


title: Leptoquark Pair Production in Hadronic Interactions

abstract:
  The scalar and vector leptoquark pair production cross sections in hadronic
collisions are calculated. In a model independent analysis we consider the most
general C and P conserving couplings of gluons to both scalar and vector
leptoquarks described by an effective low--energy Lagangian which obeys SU(3)_c
invariance. Analytrical expressions are derived for the differential and
integral scattering cross sections including the case of anomalous vector
leptoquark couplings, $\kappa_G$ and $\lambda_G$, to the gluon field. Numerical
predictions are given for the kinematic range of the TEVATRON and LHC. The pair
production cross sections are also calculated for the resolved photon
contributions to $ep \rightarrow e \overline{\Phi} \Phi X$ at HERA and LEP
$\otimes$ LHC, and for the process $\gamma \gamma \rightarrow \Phi \overline
{\Phi}X$ at possible future $e^+e^-$ linear colliders and $\gamma \gamma$
colliders. Estimates of the search potential for scalar and vector leptoquarks
at present and future high energy colliders are given.


title:
Mechanisms of the reaction pi^-p --> a^0_0(980)n --> p-^0 eta n at high
  energies

abstract:
  The main dynamical mechanisms of the reaction $\pi^-p \rightarrow a^0_0
(980)n \rightarrow \pi^0\eta n$ at high energies, currently investigated at
Serpukhov and Brookhaven, are considered in detail. It is shown that the
observed forward peak in its differential cross section can be explained within
the framework of the Regge pole model only by the conspiring $\rho_2$ Regge
pole exchange. The tentative estimates of the absolute $\pi^-p \rightarrow
a^0_0(980)n \rightarrow \pi^0\eta n$ reaction cross section at $P_{lab}^{\pi^-}
= 18$ GeV/c are obtained: $\sigma\approx200$ nb and, in the forward direction,
$d\sigma/dt\approx940$ nb/GeV$^2$. The contribution of the one pion exchange,
which is forbidden by $G$-parity and which can rise owing to the
$f^0_0(980)-a^0_0(980)$ mixing, is also estimate. A role of the Regge cuts in
the non-flip helicity amplitude is briefly examined and a conclusion is made
that the contributions of the cuts have to be inessential in comparison with
the conspiring $\rho_2$ Regge pole exchange.


title: Accelerator Constraints on Neutralino Dark Matter

abstract:
  The constraints on neutralino dark matter \chi obtained from accelerator
searches at LEP, the Fermilab Tevatron and elsewhere are reviewed, with
particular emphasis on results from LEP 1.5. These imply within the context of
the minimal supersymmetric extension of the Standard Model that m_\chi \ge 21.4
GeV if universality is assumed, and yield for large tan\beta a significantly
stronger bound than is obtained indirectly from Tevatron limits on the gluino
mass. We update this analysis with preliminary results from the first LEP 2W
run, and also preview the prospects for future sparticle searches at the LHC.


title: Glueballs: Charmonium Decay and $\bar p p$ Annihilation

abstract:
  The vector glueball $O$, made of 3 valence gluons, is expected to be
``clean": it mixes less with quarkonia, but mediates OZI violations. The recent
$0^{++} $ glueball candidate and the persistence of the $J/\psi, \psi' \to
\rho\pi$ puzzle suggest $m_O\simeq m_{J/\psi}$, with mixing angle $\sim 2^\circ
- 4^\circ$, hence $\Gamma(O\to \rho\pi$, $K^+K^-$, $e^+e^-) \sim$ MeV, few keV,
few eV. Lower and upper bounds on $\Gamma_O$ can be argued from $e^+e^- \to
\rho\pi$ energy scan data and the condition $B(O\to \rho\pi) > B(J/\psi\to
\rho\pi)$. $O$ dominance may explain the ``large" OZI violation in $^1S_0(\bar
pp)\to \phi\gamma$ vs. $\omega\gamma$.


title: (D* to D + gamma) and (B* to B + gamma) as derived from QCD Sum Rules

abstract:
  The method of QCD sum rules in the presence of the external electromagnetic
$F_{\mu\nu}$ field is used to analyze radiative decays of charmed or bottomed
mesons such as $D^{\ast}\to D\gamma$ and $B^{\ast}\to B\gamma$, with the
susceptibilities obtained previously from the study of baryon magnetic moments.
Our predictions on $D^{\ast}$ decays agree very well with the experimental
data. There are differences among the various theoretical predictions on
$B^{\ast}$ decays but the data are not yet available.


title:
Higher-Order QCD Corrections in Hadron Collisions: Soft-Gluon
  Resummation and Exponentiation

abstract:
  I briefly review some recent results on soft-gluon resummation and present
applications to heavy-quark and jet production in hadron collisions.


title:
Nonet Classification of Scalar/Isoscalar Resonances below 1900 MeV: the
  Existence of an Extra Scalar State in the Region 1200-1600 MeV

abstract:
  A classification of the $IJ^{PC}=00^{++}$ mesons is performed on the basis of
the K-matrix analysis of meson spectra in the reactions: (i) GAMS data on $\pi
p\to \pi^0\pi^0 n$, $\eta\eta n$, $\eta\eta' n$; (ii) Crystal Barrel data on
$p\bar p~(at~rest)\to \pi^0\pi^0\pi^0$, $\pi^0\pi^0\eta$, $\pi^0\eta\eta$;
(iii) CERN-M\"unich data on $\pi p\to \pi^+\pi^- n$; (iiii) BNL data on $\pi
N\to K\bar K N$. The analysis points to the existence of four comparatively
narrow scalar resonances which correspond to the following poles of the
scattering amplitude (in MeV): $(1015\pm 15)- i(43\pm 8)$, $(1300\pm
20)-i(120\pm 20)$, $(1499\pm 8)-i(65\pm 10)$ and $(1780\pm 30)-i(125\pm 70)$.
The scattering amplitude also has a fifth pole $f_0(1530^{+90}_{-250})$ at the
complex mass $(1530^{+90}_{-250}) - i(560\pm 140)$. The masses of the K-matrix
poles (bare states) are at $720\pm 100$ MeV, $1230\pm 50$ MeV, $1260\pm 30$
MeV, $1600\pm 50$ MeV and $1810\pm 30$ MeV. The quark content of the bare
states is analyzed using the values of their couplings to the $\pi\pi$, $K\bar
K$, $\eta\eta$ and $\eta\eta'$. It is shown that one of the bare states in the
mass region 1200-1600 MeV is superfluous for the $q\bar q$ classification and
should be considered as the lightest glueball.


title:
Finiteness of Hot Classical Scalar Field Theory and the Plasmon Damping
  Rate

abstract:
  We investigate the renormalizability of the classical $\phi^4$ theory at
finite temperature. We calculate the time-dependent two point function to two
loop order and show that it can be rendered finite by the counterterms of the
classical static theory. As an application the classical plasmon damping rate
is found to be $\gamma = \lambda^2 T^2/1536 \pi m$. When we use the high
temperature expression for $m$ given by dimensional reduction, the rate is
found to agree with the quantum mechanical result.


title: The tau forward-backward Asymmetry within Grand Unified Theories

abstract:
  We will study some possible non universal corrections that could affect
single measurements of the Weinberg angle sin^2(theta) (leaving the full
average essentially unchanged). We will concentrate on the class of the models
that introduces a new light gauge boson and an extended Higgs sector, but we
restrict the Higgs charges choice in order to automatically achieve zero mixing
at the tree level between the Z_0 and the Z'. This will more naturally keep
small the universal effects with a relatively light Z', but it will imply only
vector-like coupling between this boson and the standard fermions. A SO(10)
gauge boson which distinguishes between families can have such properties and
could explain a deviation in the tau forward-backward asymmetry without
affecting the tau polarization measurements at LEP.


title:
Measuring the Higgs to Photon-Photon Branching Ratio at the Next Linear
  $e^+e^-$ Collider

abstract:
  We examine the prospects for measuring the photon-photon branching ratio of a
Standard-Model-like Higgs boson ($h$) at the Next Linear $e^+e^-$ Collider when
the Higgs boson is produced via $W^+W^-$--fusion: $e^+e^-\to\nu_e \bar\nu_e h$.
In particular, we study the accuracy of such a measurement and the statistical
significance of the associated signal as a function of the electromagnetic
calorimeter resolution and the Higgs boson mass. We compare results for the
$W^+W^-$--fusion production/measurement mode with the results obtained for the
$e^+e^-\rightarrow Z^*\rightarrow Z h$ production/measurement mode in a
parallel earlier study.


title:
A test of the instanton vacuum chiral quark model with axial anomaly
  low-energy theorems

abstract:
  The QCD + QED axial anomaly low-energy theorems are applied to estimate the
accuracy of an instanton vacuum - based chiral quark model. The low-energy
theorems give an exact relation between the matrix elements of the gluon and
photon parts of the QCD + QED axial anomaly operator equation. The matrix
elements between vacuum and two photon states and between vacuum and two gluon
states are calculated for arbitrary N_f. It is shown that this model does
satisfy the low-energy theorems with an accuracy of $\sim 17%$. We estimate
also the contribution of the nonperturbative conversion of gluons into photons
to the decay $\eta ' \rightarrow 2 \gamma$ and compare with experimental data.