title: Rates and Distributions in Tau Decay

abstract:
  Semileptonic decays of polarised $\tau$ leptons are investigated. Predictions
for the rate, based on CVC and chiral Lagrangians, are contrasted with
experiments. Predictions for the angular distributions of three meson final
states are given. Emphasis is put on studies in electron-positron annihilation
where the neutrino escapes detection and the $\tau$ restframe cannot be
reconstructed. It is shown that the form factors can be measured in ongoing
high statistics experiments. Of particular interest for the three meson case
are the distribution of the normal to the Dalitz plane and the distribution
around this normal. At LEP these distributions allow for an improved
measurement of the $\tau$ polarisation. Implications are considered for an
experiment where the $\tau$ restframe is reconstructed. It is shown that the
measurement of impact parameters with the help of vertex detectors allows a
full kinematic reconstruction, including the direction of the $\tau$ and the
missing neutrino momentum.


title:
Constraints on discrete symmetries from anomaly cancellation in
  compactified superstring theories

abstract:
  Compactified string theories give rise to discrete symmetries which are
essential if they are to provide a realistic low energy theory. We find that in
a class of four dimensional string theories these symmetries are constrained by
similar conditions to those discrete anomaly cancellation conditions found in
the case the discrete symmetry is a residue of a spontaneously broken gauge
symmetry. Such conditions strongly constrain the allowed form of the low energy
effective theory.


title: More about discrete symmetries in compactified string theories

abstract:
  We discuss discrete symmetries in several string compactification schemes.
The same constraints on the light spectra as for Gepner models \cite{rosss} are
found in various cases for non-$R$ symmetries. The analogous constraints for
$R$ symmetries are also established.Therefore it seems natural to conjecture
that they always apply.


title:
Equations of Motion for Effective Lagrangians and Penguins in Rare
  B-Decays

abstract:
  We study the application of the classical equations of motion (EOM) within
the framework of an effective low-energy Lagrangian treated at the loop level.
Gauge-fixing and ghost terms, which enter naturally in the EOM, are found to
lead to no physical effects --- neither through operator mixing nor in matrix
elements. Beyond first order in the effective interactions, contact terms have
to be included when reducing the effective Lagrangian and we present an
explicit procedure to construct them. Applied to (hadronic) rare B-decays, the
EOM drastically simplify the effective Lagrangian and its matching to the
underlying theory, and certain cancellations of large (logarithmic)
contributions become more transparent. Finally, we discuss details of the
`matching' of the effective Lagrangian, which may be helpful in incorporating
short distance QCD corrections in further phenomenological studies.


title: $SO(10)$ Operator Analysis For $\nu_\mu \nu_\tau$ Oscillations

abstract:
  In grand unified theories the flavor mixing angles of leptons are related to
those of quarks. In this paper we study SO(10) theories with a precise group
theoretic relation at the GUT scale for mixing between the heaviest two
generations: $\thetuto = \kappa \abs{\vcbo}$. A comprehensive operator search
yields all possible cases where $\kappa$ is a group theory Clebsch. The
resulting predictions for $\nu_\mu \nu_\tau$ oscillations are scaled from the
grand to the weak scales. We find that all but one of the models which have
such a relationship between $\thetuto$ and $\vcbo$, and are not already
excluded, will be probed by the CHORUS and NOMAD experiments. A more precise
mixing measurement, for example by the proposed P803 experiment, could
distinguish between the models.


title: Automatic Gauged R-Parity

abstract:
  In the minimal supersymmetric standard model, the existence of R-parity is
not required for the internal consistency of the theory and might therefore be
regarded as ad hoc. I catalog some simple conditions which are sufficient to
guarantee that R-parity survives as an unbroken gauged discrete subgroup of the
continuous gauge symmetry in certain extensions of the minimal supersymmetric
standard model. If these criteria are met, R-parity is automatic. [Based on a
talk given at the International Workshop on Supersymmetry and Unification of
Fundamental Interactions (SUSY93) at Northeastern University, Boston, March
29-April 1 1993.]


title: Introduction to Thermal Field Theory

abstract:
  This is intended to be a very basic introduction and short (and of course
incomplete) overview of thermal field theory. In the first part, I introduce
the thermal propagator at a very simple level and give the Feynman rules using
the time-path contour method. In the second part, I give examples of these
rules in scalar theory and discuss the origin of the thermal mass and other
important effects as infrared divergences and phase transitions. In the third
part, I outline the resummation program of Braaten and Pisarski.


title: Dynamical zeros in neutrino-electron elastic scattering at leading order

abstract:
  We show the existence of dynamical zeros in the helicity amplitudes for
neutrino-electron elastic scattering at lowest order in the standard theory. In
particular, the $\lambda=1/2$ non-flip electron helicity amplitude in the
electron antineutrino process vanishes for an incident neutrino energy
$E_{\nu}=m_{e}/(4sin^{2}\theta_{W})$ and forward electrons (maximum recoil
energy). The rest of helicity amplitudes show kinematical zeros in this
configuration and therefore the cross section vanishes. Prospects to search for
neutrino magnetic moment are discussed.


title: Baryogenesis via lepton number violating scalar interactions

abstract:
  We study baryogenesis through lepton number violation in left-right symmetric
models. In these models the lepton number and CP violating interactions of the
triplet higgs scalars can give rise to lepton number asymmetry through
non-equilibrium decays of the $SU(2)_L$ triplet higgs and the right handed
neutrinos. This in turn generates baryon asymmetry during the electroweak
anomalous processes.


title: Probing Form Factors in Top Quark Pair Production at $e^-e^+$ Colliders

abstract:
  We describe how to probe new physics through large CP violation effects and
non--standard Z-t-t couplings via the scattering process e^-e^+ -> t tbar.
[Talk presented at the Workshop on Physics and Experiments with Linear $e^+e^-$
Colliders, Waikoloa, Hawaii, 26-30 April 1993.]


title: Signals of New Leptons

abstract:
  We discuss the production of heavy leptons at a future high--energy $e^+e^-$
linear collider with a center of mass energy of 500 GeV. Signals and
backgrounds are analyzed for their single production in association with
ordinary leptons. [Talk given by A.D. at the second Workshop on "Physics and
Experiments with Linear e+e- Colliders", Waikoloa, Hawaii, April 1993].


title: Radiative Corrections to $W$ Pair Production at High Energies

abstract:
  Radiative Corrections to $W$ Pair Production and effects of finite width of
the $W$ bosons are studied using the Monte Carlo {\tt WOPPER}. As an example
the influence of QED radiative corrections on the reconstruction of the $W$
helicities at LEP 200 and a future 500 GeV $e^+ e^-$ collider is discussed.


title: PCAC relation for Dstar -> D axial form factors

abstract:
  A relation among the form factors of $<D \mid A_\mu \mid D^*>$ at $q^2 \to 0$
is derived. It is verified to lowest order in both the $1/m_c$ expansion and
the expansion in number of derivatives using the effective lagrangian that
incorporates the heavy quark symmetries for the b and c quarks, and the chiral
symmetry for the u, d, s quarks.


title: Sphaleron Effects Near the Critical Temperature

abstract:
  We discuss one-loop radiative corrections to the sphaleron-induced baryon
number-violating transition rate near the electroweak phase transition in the
standard model. We emphasize that in the case of a first-order transition a
rearrangement of the loop expansion is required close to the transition
temperature. The corresponding expansion parameter, the effective 3-dimensional
gauge coupling approaches a finite $\lambda$ dependent value at the critical
temperature.
  The $\lambda$
  (Higgs mass) dependence of the 1-loop radiative corrections is discussed in
the framework of the heat kernel method. Radiative corrections are small
compared to the leading sphaleron contribution as long as the Higgs mass is
small compared to the W mass. To 1-loop accuracy, there is no Higgs mass range
compatible with experimental limits where washing-out of a B+L asymmetry could
be avoided for the minimal standard model with one Higgs doublet.


title: Non-Leptonic Kaon Decays and the Chiral Anomaly

abstract:
  An investigation is performed of all non-leptonic kaon decays sensitive to
the chiral anomaly. Within the framework of chiral perturbation theory, there
are two classes of anomalous amplitudes at $O(p^4)$: reducible and direct
contributions. Only radiative transitions are affected by the anomaly. The
phenomenology of the decays $K_L \to \pi^+ \pi^- \gamma$ and $K^+ \to \pi^+
\pi^0 \gamma$ is studied in detail. Including the dominant contributions of
$O(p^6)$, the experimentally observed dependence of the direct emission
amplitude for $K_L \to \pi^+ \pi^- \gamma$ on the photon energy can be
understood. A survey is made of the rare ``anomalous'' decays $K \to \pi \pi
\gamma \gamma$ and $K \to 3 \pi \gamma (\gamma)$, including some numerical
estimates.


title: Cusp Annihilation on Ordinary Cosmic Strings

abstract:
  The order of magnitude of energy emission from cusps to light bosons on
ordinary cosmic strings is calculated perturbatively. The analysis is
applicable to both closed string loops and long cosmic strings. The
perturbative result obtained here is much less than what is found by
non-perturbative approximations.


title: The Mass of the Heavy Axion $\eta_6$

abstract:
  If electroweak dynamical symmetry breaking is due to a chiral condensate of
color sextet quarks, dynamics analagous to ``walking technicolor'' will enhance
the condensate by orders of magnitude compared to the electroweak chiral scale.
This enhancement compensates for the exponential suppression of electroweak
scale color instanton interactions. As a result the $\eta_6$ axion can
naturally aquire an electroweak scale mass.


title: Exact Relations for Heavy-Light Quark Systems

abstract:
  We derive general relations among hadronic form factors involving one heavy
meson $b\bar{q}$ and another, not necessarily heavy, meson $Q\bar{q}$. The
relations are valid to all orders of mass corrections of $m_Q$ .


title: TeV Muons in Hadronic Showers

abstract:
  {}From the study of the multiple muon events in deep underground detectors,
it is possible to extract information about the spectrum and composition of the
primary cosmic rays. In this work the number of TeV muons produced by a primary
cosmic ray of a given energy and zenith angle is computed using analytic and
montecarlo methods, for a family of simplified models as description of the
properties of hadronic interactions. The effects of the uncertainties in our
knowledge of the hadronic cross sections in the calculation of TeV muons are
discussed.


title: Phenomenology of $B_s$ Decays

abstract:
  Using the QCD sum rules technique we study several aspects of the
phenomenology of the b-flavoured strange meson $B_s^0$. In particular, we
evaluate the mass of the particle, the leptonic constant and the form factors
of the decays $\overline {B_s^0} \to D^{+}_s \ell^- \bar\nu$, $\overline
{B_s^0} \to D^{*+}_s \ell^- \bar\nu$, $\overline {B_s^0} \to K^{*+} \ell^-
\bar\nu$. We also calculate, in the factorization approximation, a number of
two-body non leptonic $\overline {B_s^0}$ decays.


title:
Next--to--Leading Order Corrections to Meson Masses in the Heavy Quark
  Effective Theory

abstract:
  We use the QCD sum rule approach to calculate the splitting between vector
and pseudoscalar mesons containing one light and one heavy quark, and the
kinetic energy of the heavy quark. Our result for the splitting induced by the
chromomagnetic interaction agrees to the experimental data on charm and beauty
mesons. For the matrix element of the kinetic energy operator, we obtain the
value $K=-(0.60\pm 0.10)\, {\rm GeV}^2$.


title:
Twisting Toroidal Magnetic Fields and the Seasonal Oscillation of the
  Solar Neutrino Flux II

abstract:
  An intriguing possibility is explored that the solar neutrino data could be
used as a probe to the magnetic field structure in the sun. Various cyclic
phenomena occurring on the surface of the sun have been accounted for by the
so-called dynamo-mechanism. According to this, a self-generating mechanism of
solar cyclic activities gives rise to twisting toroidal magnetic fields in the
convective zone. Although its magnitude is not known, the orientation of the
twist is certainly opposite in northern and southern hemispheres of the sun. We
show by numerical calculation that the solar neutrino flux, being sensitive to
the twist, could exhibit observable seasonal oscillation, provided that the
twist is sizable in magnitude and the neutrinos have reasonably large magnetic
moments. This oscillation is ascribed to the fact that the earth's orbit is
slightly inclined to the sun's equator, and that solar neutrinos pass through
the northern (southern) hemisphere of the sun around September (March). We also
argue that similar seasonal oscillation could be exhibited in the azimuthal
asymmetry of recoiling electrons scattered by the solar neutrinos which are
expected to be observed in the super-Kamiokande detector.


title: The SUSY World

abstract:
  Summary Talk of the Workshop `Properties of SUSY particles' Erice, September
28 -- October 4, 1992.


title:
Composite Supersymmetric Axion-Dilaton-Dilatino System and the breaking
  of Supersymmetry

abstract:
  The spontaneous breakdown of the scale, the chiral and the superconformal
symmetries for a hidden $SU(N)$ gauge group is studied in an effective
lagrangean approach. The relevant low-energy degrees of freedom are taken to be
the composite Goldstone particles associated with these three broken
symmetries. Supersymmetry is spontaneously broken in the large $N$ limit and
soft breaking terms in the observable sector are generated, together with
nonrenormalisable Nambu-Jona-Lasinio type interactions.


title: Universality-Breaking Effects in Leptonic Z Decays

abstract:
  We analyze the possibility of universality violation in diagonal leptonic
decays of the $Z$ boson, in the context of interfamily "see-saw" models. In a
minimal extension of the Standard Model with right-handed neutrino fields, we
find that universality-breaking effects increase quadratically with the heavy
Majorana neutrino mass and may be observed in the running $LEP$ experiments.


title: Two-Body Nonleptonic Decays of Charmed Mesons

abstract:
  Two-body nonleptonic decays of charmed mesons are studied on the basis of a
simple pole-dominance model involving the vector, pseudoscalar and axial-vector
meson poles.


title:
Out of Equilibrium Phase Transitions and a Toy Model for Disoriented
  Chiral Condensates

abstract:
  We study the dynamics of a second order phase transition in a situation
thatmimics a sudden quench to a temperature below the critical temperature in a
model with dynamical symmetry breaking. In particular we show that the domains
of correlated values of the condensate grow as $\sqrt{t}$ and that this result
seems to be largely model independent.


title:
The Rate Difference between the Weak Decays of $t$ and $\bar{t}$ in
  Supersymmetry

abstract:
  We find that the $CP$-violating asymmetry $$ \frac{\Gamma \left(t \rightarrow
bW^+ \right) - \Gamma \left(\bar{t} \rightarrow \bar{b}W^- \right)} {\Gamma
\left(t \rightarrow bW^+ \right) + \Gamma \left(\bar{t} \rightarrow \bar{b}W^-
\right)} $$ at the one-loop order within the minimal supersymmetric extension
of the standard model is of the order of few per cent for maximal $CP$
violation. It could be measured by considering the rate difference in the
one-lepton events.


title: Flavor Dependence of Sea Quark Structure Functions

abstract:
  Quark masses are shown to play an important role in the nucleon sea. Our
analysis using massive QCD splitting functions demonstrates the existence of
two Feynman-$x$ sea regimes. For small $x$ the strange sea is larger while at
large $x$ the non-strange light sea is dominant. This crossover effect has been
observed in a phenomenological analysis by the CTEQ Collaboration. We also
investigate the charm component in the nucleon.


title: Probing the $WW\gamma$ Vertex in Radiative $b$-Quark Decays

abstract:
  The recent CLEO results on on radiative $b$-quark decays are used to derive
constraints on anomalous $WW\gamma$ couplings. These constraints are compared
with expectations from $p\bar p\rightarrow e^\pm p\llap/_T\gamma+X$ at the
Tevatron. The usefulness of exclusive radiative $B$ meson decay channels in
probing the $WW\gamma$ vertex is largely limited by present theoretical
uncertainties in the calculation of hadronic matrix elements.


title:
Supersymmetric $b \rightarrow s \gamma$ with Large Chargino
  Contributions

abstract:
  Supersymmetric (SUSY) theories are often thought to give large branching
ratios for $b \rightarrow s \gamma$ from charged Higgs loops. We show that in
many cases chargino loop contributions can cancel those of the Higgs, and SUSY
can give $B(b \rightarrow s \gamma)$ at or below the \SM\ prediction. We show
this occurs because the large stop mass splittings usually found in SUSY break
a GIM mechanism suppression. These effects are strongly enhanced by large
$\tan\beta$, so that $B(b \rightarrow s \gamma)$ is very sensitive to the value
of $\tan\beta$, contrary to what has been claimed. We also note that the
supergravity relation $B_0 = A_0-1$ is somewhat disfavored over the general
case.


title: rho, omega, phi-Nucleon Scattering Lengths from QCD Sum Rules

abstract:
  The QCD sum rule method is applied to derive a formula for the rho, omega,
phi meson-nucleon spin-isospin-averaged scattering lengths
$a_{\rho,\omega,\phi}$. We found that the crucial matrix elements are
$\langle\bar{q}\gamma_\mu D_\nu q\rangle_N$ ($q=u,d$) (twist-2 nucleon matrix
element) for $a_{\rho,\omega}$ and $m_s\langle\bar{s}s\rangle_N$ for $a_\phi$,
and obtained $a_\rho =0.14\pm 0.07$ fm, $a_\omega =0.11\pm 0.06$ fm and $a_\phi
=0.035\pm 0.020$ fm. These small numbers originate from a common factor
$1/(m_N+m_{\rho,\omega,\phi})$. Our result suggests a slight increase ($< 60$
MeV for $\rho$, $\omega$, and $<15$ MeV for $\phi$) of the effective mass of
these vector mesons in the nuclear matter (in the {\it dilute} nucleon gas
approximation). The origin of the discrepancy with the previous study was
clarified.


title:
Interpolating the Nucleon's Spin-Dependent Sum Rules at High and Low
  Energies

abstract:
  I discuss a few interpolating sum rules for spin structure functions of the
nucleon. Using the concept of duality, I argue that the $G_1$ sum rule,
including the elastic contribution, is useful for learning higher twist matrix
elements of the nucleon.


title:
Twist-Four Distributions in a Transversely-Polarized Nucleon and the
  Drell-Yan Process

abstract:
  The twist-four quark and gluon distributions in a transversely polarized
nucleon are identified and relations among them are discussed by using QCD
equations of motion. Their contribution, at the order of ${\cal O} \left( 1/Q^2
\right)$, to the Drell-Yan cross section in transversely polarized
nucleon-nucleon collisions is calculated.


title: The String Unufication of Gauge Cuoplings and Gauge Kinetic Mixings

abstract:
  In the superstring models we have not only the complete {\bf 27} multiplets
of $E_6$ but also extra incomplete $({\bf 27}+{\overline {\bf 27}})$ chiral
supermultiplets being alive at low energies. Associated with these additional
multiplets, when the gauge symmetry contains more than one $U(1)$ gauge group,
there may exist gauge kinetic mixings among these $U(1)$ gauge groups. In such
cases the effect of gauge kinetic mixings should be incorporated into the study
of unification of gauge couplings. We study these interesting effects
systematically in these models. The string threshold effect is also taken into
account. It is found that in the four-generation models we do not have a
advisable solution of string unification of gauge couplings consistent with
experimental values at the electroweak scale. We also discuss the possible
scenarios to solve this problem.


title:
High--Energy Multiparticle Distributions and a Generalized Lattice Gas
  Model

abstract:
  A simple lattice gas model in one dimension is constructed in which each site
can be occupied by at most one particle of any one of $D$ species. Particles
interact with a randomly drawn nearest neighbor interaction. This model is
capable of reproducing the factorial moments observed in high--energy
scattering. In the limit $D \rightarrow \infty$, the factorial moments of the
negative binomial distribution are obtained naturally.


title: On the Renormalization of Heavy Quark Effective Field Theory

abstract:
  The construction of heavy quark effective field theory (HqEFT) is extended to
arbitrary order in both expansion parameters $\alpha_s$ and $1/m_q$. Matching
conditions are discussed for the general case, and it is verified that this
approach correctly reproduces the infrared behaviour of full QCD. Choosing a
renormalization scheme in the full theory fixes the renormalization scheme in
the effective theory except for the scale of the heavy quark field. Explicit
formulae are given for the effective Lagrangian, and one--loop matching
renormalization constants are computed for the operators of order $1/m$.
Finally, the multiparticle sector of HqEFT is considered.


title:
FCNCs in SUSY GUTs (flavor changing neutral currents in predictive
  SUSY-GUTS)

abstract:
  Constraints from flavour changing neutral currents are discussed in the
context of predictive Grand Unified Supersymmetric Theories. Uncertainties in
the estimation of their amplitudes are minimized by using a successful mass
matrix ansatz which predicts the arbitrary parameters of the Standard Model.
Furthermore, Renormalization Group Equations are used in order to express the
sparticle masses involved, in terms of the gaugino mass $m_{1/2}$, the
universal scalar mass $m_0$ and the trilinear coupling $A$ at the GUT scale.
Modifications in the low energy expressions for the squark masses due to a
large top Yukawa coupling are also considered. The above results, reconciled
with experimental limits are used to put lower bounds on the parameters
$m_{1/2}$, $m_0$ and the low energy scalar masses.


title: Beyond the Standard Model

abstract:
  These are three lectures given at the ``Lake Louise Winter Institute", (Lake
Louise Canada, Feb 1993). A pedagogical introduction is given to attempts to
formulate a more fundamental theory of elementary particles than that provided
by the standard model. After a review of the basic elements of the standard
model, its unsatisfactory features, and ideas to modify them will be discussed.
An introduction to Technicolour, t-quark condensates, supersymmetric models,
GUT's and a brief comment on composite models follow.


title: Constraints on Extended Technicolor Models from B -> mu+ mu- X

abstract:
  A recent study by Randall and Sundrum shows that models of Extended
Technicolor (ETC) have interesting implications on rare B decays. We extend
their study to the decay B -> mu+ mu- X. ETC models with a GIM mechanism
predict a decay rate that is a factor of order 30 above the Standard Model,
violating the experimental upper bound by a factor of 2-4. ``Traditional" ETC
models predict a decay rate that is a factor of order 4 above the Standard
Model, and will be probed when an improvement in the sensitivity of experiments
by a factor of order 2-4 is achieved.


title:
Next-to-Leading Order QCD Corrections to Jet Cross Sections and Jet
  Rates in Deeply Inelastic Electron Proton Scattering

abstract:
  Jet cross sections in deeply inelastic scattering in the case of transverse
photon exchange for the production of (1+1) and (2+1) jets are calculated in
next-to-leading order QCD (here the `+1' stands for the target remnant jet,
which is included in the jet definition for reasons that will become clear in
the main text). The jet definition scheme is based on a modified JADE cluster
algorithm. The calculation of the (2+1) jet cross section is described in
detail. Results for the virtual corrections as well as for the real initial-
and final state corrections are given explicitly. Numerical results are stated
for jet cross sections as well as for the ratio $\sigma_{\mbox{\small (2+1)
jet}}/\sigma_{\mbox{\small tot}}$ that can be expected at E665 and HERA.
Furthermore the scale ambiguity of the calculated jet cross sections is studied
and different parton density parametrizations are compared.


title: Signals for Scalar Top Quark at $ep$ Collider HERA

abstract:
  In the framework of the minimal supersymmetric standard model (MSSM) and the
R-parity breaking model (RBM), we investigate production processes of the
scalar top (stop) at HERA energies. These models are characterized by the
possible existence of the light stop whose mass is lighter than those of the
top quark and the other squarks. It is shown that in the MSSM the stop pair
production via boson-gluon fusion gives a sizeable cross section and the most
serious background $ep\rightarrow ec\bar{c}X$ could be suppressed by
appropriate kinematical cuts. We also show that in the RBM the stop is singly
produced in the neutral current processes and we have a clear signal as a sharp
peak in the Bjorken parameter $x$ distribution of the scattered electron.


title: Hard $\gamma \gamma$ Collisions at Future $e^+ e^-$ LINACs

abstract:
  We update our previous calculation of di--jet production in two--photon
collisions at future \ee\ colliders, including both beam-- and bremsstrahlung.
We then discuss the production of heavy ($c,b,t$) quarks. Our study
re--confirms that colliders with much beamstrahlung offer no physics advantages
over designs with little beamstrahlung.


title: On the Proton Form Factors in the Time-Like Region

abstract:
  The process $ \bar{p} p \rightarrow e^{-} e^{+} $ is considered in the
general case of polarized initial particles. A relation between the difference
of the phases of the electromagnetic form factors $G_M$ and $G_E$ in the
time-like region and measurable asymmetries is derived. It is shown that the
moduli of the form factors can be determined from measurements of the total
unpolarized cross section and of the integral asymmetry for longitudinally
polarized (or transversely polarized) $\bar{p}$ and $p$. The behaviour of the
proton form factors at high $q^2$ in the time-like region is also discussed.
From the Phragm\'en-Lindel\"of's theorem it follows that the asymptotical
behaviour of the form factors in the space-like and time-like regions must be
the same. An analysis of experimental data in both regions based on
perturbative QCD is presented.


title: $\Upsilon$ decay into charmonium and the color octet mechanism

abstract:
  A factorization theorem for $P$-wave quarkonium production, recently derived
by Bodwin, Braaten, Yuan and Lepage, is applied to $\Upsilon \to \chi_{cJ} +
X$, where $\chi_{cJ}$ labels the ${}^3 P_J$ charmonium states. The widths for
$\chi_{cJ}$ production through color-singlet $P$-wave and color-octet $S$-wave
$c \bar c$ subprocesses are computed each to leading order in $\alpha_s$.
Experimental data on $\Upsilon \to J / \psi + X$ is used to obtain an upper
bound on a nonperturbative parameter (related to the probability for
color-octet $S$-wave $c \bar c$ hadronization into $P$-wave charmonium) that
enters into the factorization theorem. The bound obtained here adds to the
limited information so far available on the color-octet mechanism for $P$-wave
quarkonium production.


title: A New Class of Majoron-Emitting Double-Beta Decays

abstract:
  Motivated by the excess events that have recently been found near the
endpoints of the double beta decay spectra of several elements, we re-examine
models in which double beta decay can proceed through the neutrinoless emission
of massless Nambu-Goldstone bosons (majorons). Noting that models proposed to
date for this process must fine-tune either a scalar mass or a VEV to be less
than 10 keV, we introduce a new kind of majoron which avoids this difficulty by
carrying lepton number $L=-2$. We analyze in detail the requirements that
models of both the conventional and our new type must satisfy if they are to
account for the observed excess events. We find: (1) the electron sum-energy
spectrum can be used to distinguish the two classes of models from one another;
(2) the decay rate for the new models depends on different nuclear matrix
elements than for ordinary majorons; and (3) all models require a (pseudo)
Dirac neutrino, having a mass of a several hundred MeV, which mixes with
$\nu_e$.


title:
Destabilizing Divergences in Supergravity-Coupled Supersymmetric
  Theories

abstract:
  Nonrenormalizable couplings in supergravity-coupled supersymmetric theories
can give rise to power-law divergences that destabilize the weak-scale
hierarchy. For the case of the standard-model gauge group, the problem can
arise in theories with \321 gauge-singlet chiral superfields. The minimal
supersymmetric standard model is free from such destabilizing divergences.


title: A 1993 Look at the Lower Bound on the Top Quark Mass from CP Violation

abstract:
  We point out that the lower bound on $m_t$ from the CP violation parameter
$\epsilon_K$ has increased considerably. Using Wolfenstein parametrization of
the CKM matrix we derive an analytic expression for this bound as a function of
$\mid V_{cb}\mid, \mid V_{ub}/V_{cb}\mid$ and the non-perturbative parameter
$B_K$. For $B_K\leq 0.80,\mid V_{cb} \mid\leq 0.040$ and $\mid
V_{ub}/V_{cb}\mid\leq 0.10$ we find $m_t > 130 GeV$. However, for $B_K \leq
0.70, \mid V_{cb}\mid \leq 0.038 $ and $\mid V_{ub}/V_{cb}\mid \leq 0.08$ the
bound is raised to $m_t > 205~GeV$. The lower bound on $m_t$ from $B^o-\bar
B^o$ mixing is also reconsidered.


title: On The Exact Implementation Of Gauss' Law In Yang-Mills Theory

abstract:
  It is possible to find different sets of local coordinates in the field space
of Yang-Mills theories which implement Gauss' law manifestly for physical
states. The singular points of the transformations to these gauge-invariant
coordinates induce energy barriers in the Hamiltonian much like angular
momentum in quantum mechanics, and these formulations suggest a vacuum state
functional qualitatively different from the perturbative one. Lecture given at
the XIII Particles and Nuclei International Conference, Perugia, Italy, June 28
- July 2, 1993.


title: Light Gluinos and Unification of Couplings

abstract:
  We analyze the implications of the light gluino scenario for the unification
of gauge and Yukawa couplings within the minimal supersymmetric standard model.
Within this scheme all fermionic supersymmetric particles are naturally light,
while the scalar partners of quarks and leptons, together with the heavy Higgs
doublet may be heavy. This implies both a bound on $\tan\beta < 2.3$, in order
to fulfill the experimental constraints on the chargino masses, and a strong
correlation between $\sin^2\theta_W(M_Z)$ and $\alpha_3(M_Z)$, due to the
suppression of the supersymmetric threshold corrections to the low energy
values of the gauge couplings. Assuming the scalar sparticles to be lighter
than 10 TeV, the physical top quark mass is constrained to be 145 GeV $< M_T <$
210 GeV for $\tan\beta>1$, while the strong gauge coupling values,
$0.122\leq\alpha_3(M_Z) \leq 0.133$, are in good agreement with the measured
LEP ones. We also show that a relaxation of some of the conventional
assumptions is necessary in order to achieve radiative breaking of the
electroweak symmetry within the grand unification scheme.


title: Phase Structure of a Quantized Chiral Soliton on S^3

abstract:
  A quantization of a breathing motion of a rotating chiral soliton on $S^3$ is
performed in terms of a family of trial functions for a profile function of the
hegdehog ansatz. We determine eigenenergies of the quantized $S^3$ skyrmion by
solving the Schr\"odinger equation of the breathing mode for several lower spin
and isospin states varying the Skyrme term constants $e$. When $S^3$ radius is
smaller than $2/ef_\pi$, where $f_\pi$ is the pion decay constant, we always
obtain a conformal map solution as the lowest eigenenergy state. In the
conformal map case, allowed states have only symmetric or anti-symmetric wave
function under inversion of a dynamical variable describing the breathing mode.
As the $S^3$ radius increases the energy splitting between the symmetric and
anti-symmetric states rapidly decreases and two states become completely
degenerate state. When the $S^3$ radius larger than $3/ef_\pi$, for the small
Skyrme term constant $e$ the lowest eigenenergy states are obtained with the
profile function given by an arccosine form which is almost the same to those
of usual $R^3$ skyrmion. When the effects of the Skyrme term are weak, i.e.
large $e$, the lowest energy states are obtained by the profile function of
conformal map, which correspond to the \lc\lc frozen states" for the $R^3$
skyrmion as the limit of $S^3$ radius $ \to \infty$.


title: Particle Spectrum in Supersymmetric Models with a Gauge Singlet

abstract:
  We scan the complete parameter space of the supersymmetric standard model
extended by a gauge singlet, which is compatible with the following
constraints: universal soft supersymmetry breaking terms at the GUT scale,
finite running Yukawa couplings up to the GUT scale and present experimental
bounds on all sparticles, Higgs scalar and top quark. The full radiative
corrections to the Higgs potential due to the top/stop sector are included. We
find a lower limit on the gluino mass of 160 GeV, upper limits on the lightest
neutral scalar Higgs mass dependent on $m_{top}$ and the size of the soft
supersymmetry breaking terms, and the possibility of a Higgs scalar as light as
10 GeV, but with reduced couplings to the Z boson.


title:
Standard and hypergeometric representations for loop diagrams and the
  photon-photon scattering

abstract:
  By using the example of photon-photon scattering box diagrams, different
representations for loop integrals are discussed. A connection between
hypergeometric representation and dilogarithms is derived. An explicit analytic
continuation formula to large values of Mandelstam variables is constructed.


title: Single Leptoquark Production at $e^+e^-$ and $\gamma\gamma$ Colliders

abstract:
  We consider single production of leptoquarks (LQ's) at $e^+e^-$ and
$\gamma\gamma$ colliders, for two values of the centre-of-mass energy,
$\sqrt{s}=500$ GeV and 1 TeV. We find that LQ's which couple within the first
generation are observable for LQ masses almost up to the kinematic limit, both
at $e^+e^-$ and $\gamma\gamma$ colliders, for the LQ coupling strength equal to
$\alpha_{em}$. The cross sections for single production of $2^{nd}$- and
$3^{rd}$-generation LQ's at $e^+e^-$ colliders are too small to be observable.
In $\gamma\gamma$ collisions, on the other hand, $2^{nd}$-generation LQ's with
masses much larger than $\sqrt{s}/2$ can be detected. However,
$3^{rd}$-generation LQ's can be seen at $\gamma\gamma$ colliders only for
masses at most $\sim\sqrt{s}/2$, making their observation more probable via the
pair production mechanism.


title: Evolution of cosmic string configurations

abstract:
  We extend and develop our previous work on the evolution of a network of
cosmic strings. The new treatment is based on an analysis of the probability
distribution of the end-to-end distance of a randomly chosen segment of
left-moving string of given length. The description involves three distinct
length scales: $\xi$, related to the overall string density, $\bar\xi$, the
persistence length along the string, and $\zeta$, describing the small-scale
structure, which is an important feature of the numerical simulations that have
been done of this problem. An evolution equation is derived describing how the
distribution develops in time due to the combined effects of the universal
expansion, of intercommuting and loop formation, and of gravitational
radiation. With plausible assumptions about the unknown parameters in the
model, we confirm the conclusions of our previous study, that if gravitational
radiation and small-scale structure effects are neglected, the two dominant
length scales both scale in proportion to the horizon size. When the extra
effects are included, we find that while $\xi$ and $\bar\xi$ grow, $\zeta$
initially does not. Eventually, however, it does appear to scale, at a much
lower level, due to the effects of gravitational back-reaction.


title:
Hard Thermal Loops, Gauged WZNW Action and the Energy of Hot Quark-Gluon
  Plasma

abstract:
  The generating functional for hard thermal loops in QCD is rewritten in terms
of a gauged WZNW action by introducing an auxiliary field. This shows in a
simple way that the contribution of hard thermal loops to the energy of the
quark-gluon plasma is positive.


title:
Some Exact Results for Two-Loop Diagrams with Three and Four External
  Lines

abstract:
  Evaluation of three- and four-point diagrams with massless internal particles
and arbitrary external momenta is considered. Exact results for some two-loop
diagrams (planar and non-planar three-point contributions and the "double box"
diagram) are obtained in terms of polylogarithms.


title: Mini-charged tau neutrinos?

abstract:
  Theoretically, the electric charge of the tau neutrino may be non-zero. The
experimental bound on the electric charge of the tau neutrino is many orders of
magnitude weaker than that for any other known neutrino. If the tau neutrino
does have a small electric charge, and its mass is greater than 1 MeV, then it
can annihilate sufficiently in the early Universe by electromagnetic
interactions to avoid conflict with the standard cosmology model. A novel
feature of this scenario is that there can be effectively less than three
neutrino species present during nucleosynthesis.


title:
Novel Quark Fragmentation Functions and the Nucleon's Transversity
  Distribution

abstract:
  We define twist-two and twist-three quark fragmentation functions in Quantum
Chromodynamics (QCD) and study their physical implications. Using this
formalism we show how the nucleon's transversity distribution can be measured
in single pion inclusive electroproduction.


title: Radiative Heavy Meson Transitions

abstract:
  We evaluate the radiative and hadronic decay rates of the $D^*$ mesons using
the Heavy Quark Effective Theory and the Vector Meson Dominance hypothesis. We
also estimate the width of the $B^*$ electromagnetic transitions and the
radiative decays of positive parity $J^P=0^+, 1^+$ charmed mesons.


title:
Reduction of Vector and Axial--Vector Fields in a Bosonized
  Nambu--Jona--Lasinio Model

abstract:
  We derive the effective action for pseudoscalar mesons by integrating out
vector and axial--vector collective fields in the generating functional of the
bosonized NJL--model. The corresponding modifications of the nonlinear
effective Lagrangian and the bosonized currents, arising at $O(p^4)$, are
discussed.


title:
Predictions for Semileptonic Decays $\bar{B}\to D(D^*)\pi\ell\bar{\nu}$
  and Weak Radiative Decays of Bottom Hadrons

abstract:
  The semileptonic decays $\bar{B}\to D(D^*)\pi\ell\bar{\nu}$ are analyzed by
heavy quark and chiral symmetries. The branching ratio is of order of a few
percent for $\dpi$, but it is much smaller for $\dstar$, of order
$10^{-4}-10^{-5}$. The decay mode $B^-\to D^+\pi^-e^-\bar{\nu}_e$ provides a
nice place for extracting the $D^*D\pi$ coupling constant from the semileptonic
decays of a $\bar{B}$ meson. Two types of weak radiative decays of $\bar{B}$
mesons and bottom baryons are studied. The decay $\Lambda_b^0\to
\Lambda^0\gamma$ receives the electromagnetic penguin $b\to s\gamma$
contribution and has a branching ratio of order $2\times 10^{-5}$. The
radiative decays $\bar{B}\to D^*\gamma,~
\Lambda_b^0\to\Sigma_c^0\gamma,~\Xi_b^0\to \Xi_c^0\gamma$ and
$\Xi_b^0\to{\Xi'}_c^0\gamma$ occur through $W$ exchange accompanied with a
photon emission and their branching ratios are estimated to be much smaller. We
conclude that the weak radiative decays of bottom hadrons are dominated by the
short-distance electromagnetic penguin mechanism.


title: Low Energy Constraints and Anomalous Triple Gauge Boson Couplings

abstract:
  Low energy (1-loop) constraints on anomalous triple gauge boson vertices
(TGV's) are revisited and compared to the sensitivity achievable at LEP II and
at future linear $e^+e^-$ colliders. The analysis is performed within the
framework of an effective Lagrangian of gauge invariant dimension six operators
with the gauge bosons and a single Higgs doublet field as the low energy
degrees of freedom. The low energy data do not directly bound TGV's but they
provide strong constraints on models which lead to anomalous gauge boson
interactions in addition to other low energy effects.


title: Unitarity of the Standard Model at the Higgs' Resonance

abstract:
  We compute a unitarity bound for higgs mass using one--loop corrected s--wave
partial amplitude for $Z_L Z_L \rightarrow Z_L Z_L$ scattering. We use the
equivalence theorem and show that the higgs mass has to be less than $\approx
600$ GeV in order to save the (perturbative) unitarity in the higgs' resonance
region. We also discuss about the validity of perturbation expansion in the
symmetry breaking sector.


title: Thermal Bubble Diagrams Near Zero Energy

abstract:
  The zero four-momentum and equal mass limits are taken for the bubble diagram
of scalar fields. It is seen that RTF and ITF are in complete agreement.
However contributions from this diagram to both retarded and time-ordered
functions do depend on the order of the limits and can be infinite in some
cases. This shows explicitly that the relation between the free energy and a
derivative expansion of a thermal effective action is generally much more
complicated that is the case at zero temperature.


title: Some remarks on pion condensation in relativistic heavy ion collisions

abstract:
  Recently it was pointed out that coherent or condensated states of pions may
account for the explanation of the Centauro events observed in cosmic ray
showers. We argue that an occurrence of condensed pions requires that the
system evolves far out of thermal equilibrium. Besides an unusual charge ratio
distribution we show that such a produced state also would lead to strong
isospin correlations.


title: A Global Fit to Extended Oblique Parameters

abstract:
  The STU formalism of Peskin and Takeuchi is an elegant method for encoding
the measurable effects of new physics which couples to light fermions
dominantly through its effects on electroweak boson propagation. However, this
formalism cannot handle the case where the scale of new physics is not much
larger than the weak scale. In this case three new parameters (V, W and X) are
required. We perform a global fit to precision electroweak data for these six
parameters. Our results differ from what is found for just STU. In particular
we find that the preference for S < 0 is not maintained.


title: Gluon Radiation and Top Width Effects

abstract:
  The large width of the top quark influences the way gluons are radiated in
top events, giving rise to interesting interference effects in top production
and decay. We discuss top width effects in soft guon radiation in $\ee \to \tt$
at high energies and near $\tt$ threshold.


title: High-$Q^2$ Elastic $ed$-scattering and QCD predictions

abstract:
  In the framework of pertubative QCD it is argued that in the elastic
$ed$-scattering at $Q^{2}\sim$ few $(GeV/c)^{2}$ the light-cone-frame
helicity-flip amplitudes could not be omitted. The obtained $\frac{B}{A}$ ratio
of Rosenbluth structure functions is shown to be in a good agreement with
experimental data. The high $Q^2$ behavior of tensor analysing power $T_{20}$
is discussed.


title:
Photoproduction of large-mass lepton pairs at HERA as a probe of the
  small $x$ structure of the proton

abstract:
  The photoproduction of Drell-Yan lepton pairs at HERA is studied. We show
that in the backward rapidity region the cross section is strongly sensitive to
the small-$x$ behaviour of the quark distributions in the proton, and that with
sufficient luminosity it should be possible to distinguish singular $xq \sim
x^{-1/2}$ behaviour from standard Regge $xq \sim x^0$ behaviour. The effect on
the event rate of experimental acceptance cuts is studied with the help of a
Monte Carlo event generator.


title: Bubble-Bubble Interaction in the Quark-Gluon Plasma

abstract:
  We calculate the two-body interaction of spherical hadronic bubbles immersed
in a gluon plasma at temperatures above the phase transition. Modeling the
bubbles with the MIT bag we find that the two body potential is repulsive for
all bubble-bubble distances considered. This implies that a static
configuration of spherical hadronic bubbles in a gluon background is consistent
with the bag model of QCD.


title: Precise Vacuum Stability Bound in the Standard Model

abstract:
  In the standard model, a lower bound to the Higgs mass (for a given top quark
mass) exists if one requires that the standard model vacuum be stable. This
bound is calculated as precisely as possible, including the most recent values
of the gauge couplings, corrected two-loop beta functions and radiative
corrections to the Higgs and top masses. In addition to being somewhat more
precise, this work differs from previous calculations in that the bounds are
given in terms of the poles of the Higgs and top quark propagators, rather than
''the MS-bar top quark mass''. This difference can be as large as 6-10 GeV for
the top mass, which corresponds to as much as 15 GeV for the Higgs mass lower
bound. Concentrating on the top quark mass region from 130 to 150 GeV, I find
that for $\alpha_s=0.117$, $$ m_H > 75 {\rm GeV} + 1.64 (m_t - 140 {\rm GeV}).
$$ This result increases (decreases) by 3 GeV if the strong coupling decreases
(increases) by 0.007, and is accurate to 2 GeV. If one allows for the standard
model vacuum to be unstable, then weaker bounds can be obtained.


title: Gauge created top quark condensate and heavy top

abstract:
  The scalar interaction term of the top mode standard model can be generated
by a gauge theory. It is emphasized that in this approach generalization to
family space directly yields a heavy top quark while leaving all other quarks
massless. By generating the new interaction from gauge extension to custodial
$SU(2)$, the standard model bound $m_{top} \stackrel{<}{\sim} 200 GeV$ is
pushed to $m_{top} \stackrel{<}{\sim} 270 GeV$, thereby significantly reducing
the amount of finetuning required to match this number.


title: A New Model for Fermion Masses in Supersymmetric Grand Unified Theories

abstract:
  We present a simple model for fermion mass matrices and quark mixing in the
context of supersymmetric grand unified theories and show its agreement with
experiment. Our model realizes the GUT mass relations $m_d=3m_e$, $m_s=
m_\mu/3$, $m_b=m_\tau$ in a new way and is easily consistent with values of
$m_t$ suggested by MSSM fits to LEP data.


title: Looking for Gluon Substructure at the Tevatron

abstract:
  The impact of nonrenormalizable gluon operators upon inclusive jet cross
sections is studied. Such operators could arise in an effective strong
interaction Lagrangian from gluon substructure and would induce observable
cross section deviations from pure QCD at high transverse jet energies.
Comparison of the theoretical predictions with recent CDF data yields a lower
limit on the gluon compositeness scale $\Lambda$. We find $\Lambda > 2.03 \TeV$
at $95\%$~CL.


title: Could There Be Something Rather Than Nothing?

abstract:
  There is increasing evidence that the universe may have a small cosmological
constant. We suggest a scheme for naturally generating a small cosmological
constant. Our idea requires the presence of a discrete accidental symmetry
which is spontaneously broken by vacuum expectation values of the fields, and
explicitly broken by high dimensional operators in the Lagrangian.


title: Aspects of Chargino-Neutralino Production at the Tevatron Collider

abstract:
  We have used ISAJET 7.0/ISASUSY 1.0 to evaluate the rates and study
distributions for trilepton events from the leptonic decays of charginos and
neutralinos produced at the Fermilab Tevatron via the reaction, $p\bar
p\rightarrow \tilde{W_1} \tilde{Z_2}$ + X for cuts inspired by the CDF and D0
experiments. We find that about 60\% of these events do not contain any jets,
and so should be easily identifiable over Standard Model backgrounds from
$t\bar{t}$ and WZ production, provided that the decay
$\tilde{Z_2}\rightarrow\tilde{Z_1}Z$ is kinematically inaccessible.
  We further show that, with suitable cuts, these backgrounds can be reduced to
less than 1-2 $fb$ even if $n_{jet} = 1$, effectively increasing the SUSY
sample by 50\%. We confirm that the signal is only rate-limited, and that the
Fermilab Tevatron after an accumulation of 100 $pb^{-1}$ of integrated
luminosity will be able to explore parameters well beyond the range of LEP and,
if sleptons are substantially lighter than squarks, close to the reach of LEP
200.


title:
Dynamical Growth Rate of a Diffuse Interface in First Order Phase
  Transitions

abstract:
  We compute the dynamical prefactor in the nucleation rate of bubbles or
droplets in first order phase transitions for the case where both viscous
damping and thermal dissipation are significant. This result, which generalizes
previous work on nucleation, may be applied to study the growth of bubbles or
droplets in condensed matter systems as well as in heavy ion collisions and in
the expansion of the early universe.


title: Topological Study of Global Quantization in Non-Abelian Gauge Theories

abstract:
  We study some topological aspects of non-abelian gauge theories intimately
connected to the Lie algebras of the gauge groups and the homotopy theory in
the generalized gauge orbit space. The physics connection to the
non-perturbative solution to strong CP problem as originally proposed by the
author is also discussed. Some relevant topological formulas are also given and
discussed. A result from the physics application is that the usual gauge orbit
space on the compactified space can contain at most a $Z_2$ monopole structure
in the SP(2N) gauge theories. Some relevance to the open universe is also
discussed. We expect that our results may also be useful to the other studies
of non-abelian gauge theories in general.


title: CP Violation Induced by Supersymmetry in $e^+e^-$ Collisions

abstract:
  We discuss the possibility of observing $CP$ violation predicted by the
supersymmetric standard model.


title: Transition from a quark-gluon plasma in the presence of a sharp front

abstract:
  The effect of a sharp front separating the quark-gluon plasma phase from the
hadronic phase is investigated. Energy-momentum conservation and baryon number
conservation constrain the possible temperature jump across the front. If one
assumes that the temperature in the hadronic phase is $T\simeq$ 200 MeV , as
has been suggested by numerous results from relativistic ion collisions, one
can determine the corresponding temperature in the quark phase with the help of
continuity equations across the front. The calculations reveal that the quark
phase must be in a strongly supercooled state. The stability of this solution
with respect to minor modifications is investigated. In particular the effect
of an admixture of hadronic matter in the quark phase (e.g. in the form of
bubbles) is considered in detail. In the absence of admixture the transition
proceeds via a detonation transition and is accompanied by a substantial
super-cooling of the quark-gluon plasma phase. The detonation is accompanied by
less supercooling if a small fraction of bubbles is allowed. By increasing the
fraction of bubbles the supercooling becomes weaker and eventually the
transition proceeds via a smoother deflagration wave.


title: Structure Functions of the Nucleon in a Statistical Model

abstract:
  Deep inelastic scattering is considered in a statistical model of the
nucleon. This incorporates certain features which are absent in the standard
parton model such as quantum statistical correlations which play a role in the
propagation of particles when considering Feynman diagrams containing internal
lines. The inclusion of the ${\cal O}(\alpha_{s})$ corrections in our numerical
calculations allows a good fit to the data for $x\geq 0.25$. The fit
corresponds to values of temperature and chemical potential of approximately
$T=0.067$ GeV and $\mu=0.133$ GeV. The latter values of parameters, however,
give rise, for all $x$, to a large value for $R=\sigma_{L}/\sigma_{T}$.


title: Dissipative Processes in an Expanding Massive Gluon Gas

abstract:
  The temperature dependence of the kinetic coefficients is obtained in the
non-perturbative region with the help of Green-Kubo-type formulae in the model
of massive gluon gas motivated by numerical results from simulations of lattice
QCD. The entropy production rate is estimated using scaling hydrodynamics. It
is shown that the increase in the viscosity coefficients leads to entropy
generation in heavy ion collision processes which could be big, especially for
temperatures close to the critical one.


title: Supersymmetric Higgs Bosons at the Limit

abstract:
  Using a combination of renormalisation group and effective potential methods,
we discuss the bound on the lightest CP-even Higgs boson mass $m_h$ in the
next-to-minimal supersymmetric standard model. We find $m_h\leq 146,139,149 \
GeV$ for $m_t=90,140,190 \ GeV$.


title: Rapidity Correlations in $W\gamma$ Production at the Tevatron

abstract:
  We study the correlation of photon and charged lepton pseudorapidities,
$\eta(\gamma)$ and $\eta(\ell)$, $\ell=e,\,\mu$, in $p\bar p\rightarrow
W^\pm\gamma+X\rightarrow \ell^\pm p\llap/_T\gamma+X$ at the Tevatron. In the
Standard Model, the $\Delta\eta(\gamma,\ell)= \eta(\gamma) - \eta(\ell)$
differential cross section is found to exhibit a pronounced dip at
$\Delta\eta(\gamma,\ell) \approx \mp 0.4$, which originates from the radiation
zero present in $q\bar q'\rightarrow W\gamma$. The sensitivity of the
$\Delta\eta(\gamma,\ell)$ distribution to higher order QCD corrections,
non-standard $WW\gamma$ couplings, and the cuts imposed is explored. The
$\Delta\eta(\gamma,\ell)$ distribution is compared with other quantities which
are sensitive to the radiation zero.


title:
Non-Perturbative Isotropic Multi-Particle Production in Yang--Mills
  Theory

abstract:
  We use singular Euclidean solutions to find multi-particle production cross
sections in field theories. We investigate a family of time-dependent O(3)
symmetrical solutions of the Yang--Mills equations, which govern the isotropic
high-energy gauge boson production. At low energies our approach reproduces the
instanton-induced cross sections. For higher energies we get new results. In
particular, we show that the cross section for isotropic multiparticle
production remains exponentially small in the running gauge coupling constant.
The result applies both to the baryon number violation in the electro-weak
theory and to the QCD jet production. We find that the isotropic multi-gluon
production cross section falls off approximately as a ninth power of energy but
possibly might be observable


title: Energy of W distribution in top quark decays

abstract:
  A relatively simple analytical formula is derived for the energy spectrum of
$W$ boson in top quark decays $t\to Wb$ including ${\cal O}(\alpha_s)$
radiative corrections. We discuss the accuracy of this formula and compare it
to a more general albeit more complicated one derived in \cite{CJK}~. A Monte
Carlo algorithm for generation of $W$ energy spectrum is briefly described.


title: Radiative Corrections to the top quark width

abstract:
  Calculations of radiative corrections to the top quark width are reviewed.
QCD effects are discussed for $t-\bar t$ systems produced in $e^+e^-$
annihilation near the energy threshold.}


title: Cosmic balloons

abstract:
  Cosmic balloons, consisting of relativistic particles trapped inside a
spherical domain wall, may be created in the early universe. We calculate the
balloon mass $M$ as a function of the radius $R$ and the energy density
profile, $\rho (r)$, including the effects of gravity. At the maximum balloon
mass $2GM/R\approx 0.52$ for any value of the mass density of the wall.


title: Can the Electric Charges of Elementary Particles Change with Time?

abstract:
  We present the limits on possible time variation of the electric charges of
quarks and leptons at the time of primordial nucleosynthesis within a model
with dequantized electric charges which allows for the case of charged neutrino
and neutron.


title: Strongly-Interacting Electroweak Sector at Future Colliders

abstract:
  If there are no light Higgs bosons found below $\cal O$(800 GeV) or so, the
interactions among longitudinally-polarized vector bosons ($\wl$) will become
strong at the TeV region, and new physics that is responsible for the
electroweak symmetry breaking must emerge at this energy scale. We discuss the
phenomenological prospects of the Strongly-interacting Electro-Weak Sector
(SEWS) at future TeV linear colliders and hadronic supercolliders.


title:
Analytic Continuation of Thermal $N$-Point Functions from Imaginary- to
  Real-Energies

abstract:
  We consider thermal $n$-point Green functions in the framework of quantum
field theory at finite temperature. We show how analytic continuations from
imaginary to real energies relate these functions originally defined in the
imaginary-time formalism to retarded and advanced real-time ones. The described
method is valid to all orders of perturbation theory. It has the further
advantage that it is independent of approximations often applied in actual
finite-order calculations.


title: Lepton pairs from thermal mesons

abstract:
  We study the net dielectron production rates from an ensemble of thermal
mesons, using an effective Lagrangian to model their interaction. The coupling
between the electromagnetic and the hadronic sectors is done through the vector
meson dominance approach. For the first time, a complete set of light mesons is
considered. We include contributions from decays of the type
V~(PS)~$\rightarrow$~PS~(V)~+~$e^+~e^-$, where V is a vector meson and PS is a
pseudoscalar, as well as those from binary reactions PS~+~PS, V~+~V, and
V~+~PS~$\rightarrow~e^+e^-$. Direct decays of the type V~$\rightarrow~e^+ e^-$
are included and shown to be important. We find that the dielectron invariant
mass spectrum naturally divides in distinct regions: in the low mass domain the
decays from vector and pseudoscalar mesons form the dominant contribution. The
pion--pion annihilation and direct decays then pick up and form the leading
signal in an invariant mass region that includes the $\rho - \omega$ complex
and extends up to the $\phi$. Above invariant mass $M\ \approx$~1~GeV other
two-body reactions take over as the prominent mechanisms for lepton pair
generation. These facts will have quantitative bearing on the eventual
identification of the quark--gluon plasma.


title:
Scheme Independence of the Effective Hamiltonian for $b \rightarrow s \,
  \gamma$ and $b \rightarrow s \, g$ Decays

abstract:
  We present a calculation of the effective weak Hamiltonian which governs $b
\rightarrow s\, \gamma$ and $b \rightarrow s \, g$ transitions in two different
renormalization schemes (NDR and HV). In the leading logarithmic approximation,
we show that the coefficients of the effective Hamiltonian are scheme
independent only when one takes correctly into account the scheme dependence of
one- and two- loop diagrams. We demonstrate that in NDR there are contributions
which were missed in previous calculations. These contributions are necessary
to obtain scheme independent coefficients in the final results.


title: Interpolating Axial Anomaly Induced Amplitudes

abstract:
  We propose an interpolating formula for the amplitude induced by the axial
anomaly, concentrating on the $\pi^0\gamma^{\ast}\gamma^{\ast}$ transition form
factor. The QCD corrections to this amplitude are generally described by two
major contributions coming from the $q\bar{q}$ bound state and the background
continuous spectrum, respectively.
  For the first contribution, we include the lowest vector bound state using
the realization of the dynamical gauge boson of hidden local symmetry. The
second contribution is included as the triangle quark loop in which a
constituent mass is adopted as a internal quark mass and the amplitudes are
smeared out around the threshold. Using the resulting form factor, we fit the
experimental data for the $\pi^0\gamma$ and the $\omega\pi^0$ transition form
factors and show that our result describes the experimental data well.


title: Axial Anomaly and Transition Form Factors

abstract:
  We investigate the properties of the amplitude induced by the anomaly. In a
relatively high energy region those amplitudes are constructed by the vector
meson poles and the anomaly terms, in which the anomaly terms can be
essentially evaluated by the triangle quark graph. We pay our attention to the
anomaly term and make intensive analysis of the existing experimental data,
i.e., the electromagnetic $\pi^0$ and $\omega$ transition form factors. Our
result shows that it is essential to use the constituent quark mass instead of
the current quark mass in evaluating the anomaly term from the triangle graph.


title: Higgs Bosons at an $\bf\epem$ Linear Collider: Theory and Phenomenology

abstract:
  I review recent developments in the theory and phenomenology of Higgs bosons
at an $\epem$ linear collider with $\sqrt s$ of order 500 GeV.


title:
Impact of QCD Corrections on the Search for the Intermediate Mass Higgs
  Boson

abstract:
  Using next-to-leading-log calculations of Higgs production and hadronic two
photon production, a signal and background study in the intermediate mass range
of the Higgs boson is done for $\sqrt{s}=$ 40 and 14 TeV. The effects of
realistic cuts, including photon isolation, are examined.


title: Observing $b \rightarrow s \, \mu^+ \mu^-$ Decays at Hadron Colliders

abstract:
  We examine the prospects for observing weak flavour-changing neutral current
(FCNC) decays of \B\ mesons at hadron colliders, including effects of anomalous
$WWZ$~vertices. Since it is very difficult to measure the inclusive rate $B
\rightarrow X_s \, \lp \lm$ one should consider exclusive modes such as
\BKsmumu\ and \BKmumu. Even though this requires one to compute hadronic matrix
elements, we show that experimentally observable quantities (ratios of decay
rates) are not strongly parametrisation dependent. Some possibilities for
reducing the theoretical uncertainties from other experimental data are
discussed.


title:
Penguin-Diagram Induced $B \rightarrow K_X\phi$ Decays in the Standard
  Model and in the Two-Higgs-Doublet Model

abstract:
  We systematically analyse the gluonic penguin-induced charmless decays $B \ra
K_X\phi$($K_X$ denotes the meson state $s\bar q \;(q=u\ {\rm or}\ d)$ ), in the
standard model and the two-Higgs-doublet model. These processes, being induced
at one-loop level, are of great importance in measuring the virtual top quark
effect in the standard model, and also in searching for the non-standard
signals in the low energy region. It is shown that the QCD effect is also
significant in these processes, as in the weak radiative processes $B \ra X_s
\gamma$. We also show that the charged Higgs contribution can not provide
sizable enhancements for the decays $B \ra K_X\phi$, in contrast to the decays
$B \ra K_X\gamma$. It is also found that processes such as $B \ra
K_1(1400)\phi$ and $B \ra K(1460)\phi$ have large branching fractions among $B
\ra K_X\phi$ decays.


title:
Large momentum expansion of two-loop self-energy diagrams with arbitrary
  masses

abstract:
  For two-loop two-point diagrams with arbitrary masses, an algorithm to derive
the asymptotic expansion at large external momentum squared is constructed. By
using a general theorem on asymptotic expansions of Feynman diagrams, the
coefficients of the expansion are calculated analytically. For some two-loop
diagrams occurring in the Standard Model, comparison with results of numerical
integration shows that our expansion works well in the region above the highest
physical threshold.


title: Radiative Corrections to the decay tau -> pi (K) nu_tau

abstract:
  We have calculated the O(alpha) radiative corrections to the tau decay tau ->
pi (K) nu, taking into account both the point meson contribution and the
structure dependent radiation. We find for the ratio Gamma(tau -> pi nu
(gamma)) / Gamma(pi -> mu nu (gamma)) a radiative correction of + 1.2% and for
Gamma(tau -> K nu (gamma)) / Gamma(K -> mu nu (gamma)) one of + 2.0%. We
compare our results with an earlier estimation and with experimental data.


title: Effective Operators and Extended Symmetry

abstract:
  In this note we expand on our previous study of the implications of LEP1
results for future colliders. We extend the effective operator-based analysis
of De R\'ujula et al. to a larger symmetry group, and show at which cost their
expectations can be relaxed. Of particular interest to experiment is a
rephrasing of our previous results in terms of the Renard et al.
parametrization for the gauge boson self-couplings (slightly extended to
include $\delta g_{\gamma}$). We suggest the use of a ($\delta g_{\gamma}$,
$\delta g_{Z}$) plot to confront the expectations of various models.


title: Top Confinement

abstract:
  A new interaction that confines the top quark at the electroweak scale is
proposed to account for a top quark mass potentially close in value to the
electroweak scale.


title: Small $x$ processes: Heavy Quark Production at High Energy

abstract:
  A brief summary is given of some recent perturbative QCD results on the
evaluation of cross sections and on the the structure of final states in
processes with incoming hadrons at small $x$. A new Monte Carlo simulation
which includes these theoretical features is described together with its
applications to the study of heavy quark production in $ep$ collisions at very
high energy. (Talk given at the XXVIIth Rencontre de Moriond, March 1993, Les
Arcs, France)


title: QCD and high energy hadronic interaction: Summary talk (theory)

abstract:
  Results presented in perturbative QCD are reviewed. The topics discussed
include: - struction functions, - heavy flavour production, - direct photon
production, - inclusive production at LHC/SSC, - small $x$ physics, - QCD jets
and - intermittency. For reference to the data in this talk see the summary
presented by J.E. Augustin.


title: Anomalous Gauge-Boson Couplings in High Energy ep Collisions

abstract:
  We investigate the sensitivity of total cross sections of $e+p \rightarrow
W,Z$ to CP-conserving non-standard $WW\gamma$ couplings. We include all the
important production mechanisms and study the dependence of the total $W$ cross
sections on the anomalous $WW\gamma$ couplings, $\kappa$ and $\lambda$. We
argue that the ratio of $W$ and $Z$ production cross sections is particularly
well suited, being relatively insensitive to uncertainties in the theoretical
and experimental parameters.


title:
Equivalence of Hamiltonian and Lagrangian Path Integral Quantization:
  Effective Gauge Theories

abstract:
  The equivalence of correct Hamiltonian and naive Lagrangian (Faddeev--Popov)
path integral quantization (Matthews's theorem) is proven for gauge theories
with arbitrary effective interaction terms. Effective gauge-boson
self-interactions and effective interactions with scalar and fermion fields are
considered. This result becomes extended to effective gauge theories with
higher derivatives of the fields.


title: Neutrinos at high energy accelerators

abstract:
  PREAMBLE, BRIEF HISTORY AND PRELIMINARIES, QUICK REVIEW OF BASIC NEUTRINO
PROPERTIES, CHARGED CURRENT NEUTRINO PROCESSES, NEUTRAL CURRENT NEUTRINO
PROCESSES, VERY HEAVY NEUTRINOS, CONCLUDING SUMMARY


title: Do Present LEP Data Provide Evidence for Electroweak Corrections?

abstract:
  The Born approximation, based on $\bar\alpha \equiv\alpha (m_Z)$ instead of
$\alpha$, reproduces all electroweak precision measurements within their
$(1\sigma)$ accuracy. The low upper limits for the genuinely electroweak
corrections constitute one of the major achievements of LEP. The astonishing
smallness of these corrections results from the cancellation of a large
positive contribution from the heavy top quark and large negative contributions
from all other virtual particles. It is precisely the non-observation of
electroweak radiative corrections that places stringent upper and lower limits
on the top mass.


title:
Radiative Kaon Decays $K^\pm\to\pi^\pm\pi^0\gamma$ and Direct CP
  Violation

abstract:
  It is stressed that a measurement of the electric dipole amplitude for direct
photon emission in $\kpm$ decays through its interference with inner
bremsstrahlung is important for differentiating among various models. Effects
of amplitude CP violation in the radiative decays of the charged kaon are
analyzed in the Standard Model in conjunction with the large $N_c$ approach. We
point out that gluon and electromagnetic penguin contributions to the
CP-violating asymmetry between the Dalitz plots of $\kpm$ are of equal weight.
The magnitude of CP asymmetry ranges from $2\times 10^{-6}$ to $1\times
10^{-5}$ when the photon energy in the kaon rest frame varies from 50 MeV to
170 MeV.


title: Technicolor with a Massless Scalar Doublet

abstract:
  We consider a minimal technicolor model in which the ordinary and technicolor
sectors are coupled by a {\it massless} scalar doublet. When technicolor
interactions become strong, the resulting technicolor condensate not only
breaks the electroweak symmetry, but also causes the scalar to develop a vacuum
expectation value. With the appropriate choice of the scalar's Yukawa
couplings, fermion masses are generated, giving us the conventional pattern of
flavor symmetry breaking. Although no explicit scalar mass term appears in the
full lagrangian of the model, the pseudoscalar states that remain in the
low-energy effective theory gain sufficient mass through technicolor
interactions to evade detection. We show that this model does not generate
unacceptably large flavor changing neutral currents, and is consistent with the
experimental constraints on oblique electroweak radiative corrections. We
determine the experimentally allowed region of the model's parameter space, and
discuss the significance of a phenomenologically viable model that has no
arbitrary dimensionful parameters. In terms of parameter counting, our model is
the simplest possible extension of the standard model.


title:
Parton-Parton Elastic Scattering and Rapidity Gaps at SSC and LHC
  Energies

abstract:
  The theory of the perturbative pomeron, due to Lipatov and collaborators, is
used to compute the probability of observing parton-parton elastic scattering
and rapidity gaps between jets in hadron collisions at SSC and LHC energies.


title: Parton-Parton Elastic Scattering and Rapidity Gaps at Tevatron Energies

abstract:
  The theory of the perturbative pomeron, due to Lipatov and collaborators, is
used to compute the probability of observing parton-parton elastic scattering
and rapidity gaps between jets in hadron collisions at Tevatron energies.


title: Non-universal soft scalar masses in supersymmetric theories

abstract:
  The existence of non--universal soft masses is the most general situation in
supersymmetric theories. We study the consecuences that this situation has for
the low--energy sparticle spectrum. In particular, we analize in detail the
contribution to the scalar mass renormalization group equations of the $U(1)_Y$
D--term. We obtain analytic expressions for the evolution of masses of the
three generations and these allow us to show that such a contribution can
produce important modifications on the spectrum. The necessity to avoid flavour
changing neutral currents does not constrain this result. Finally, we discuss a
realistic example in the context of string theory where the departure from
universality is large.


title: The Supersymmetric Top-Ten Lists

abstract:
  Ten reasons are given why supersymmetry is the leading candidate for physics
beyond the Standard Model. Ultimately, the experimental discovery of
supersymmetric particles at future colliders will determine whether
supersymmetry is relevant for TeV scale physics. The grand hope of
supersymmetry enthusiasts is to connect TeV scale supersymmetry with Planck
scale physics. The ten most pressing theoretical problems standing in the way
of this goal are briefly described.


title: Two Body Non Leptonic Decays of B and B_s Mesons

abstract:
  We perform an analysis of two-body non leptonic decays of $B$ and $B_s$
mesons in the factorization approximation. We make use of the semileptonic
decay amplitudes previously calculated on the basis of an effective lagrangian
satisfying chiral and heavy quark symmetries and including spin 1 resonances.
Exclusive semileptonic $D$-decay data are used as experimental input. Our
results compare favorably with data, whenever they are available and indicate a
positive value for the ratio of non leptonic coefficients $a_2/a_1$, similarly
to previous studies.


title:
Can the Axions of Standard--like Superstring Models Solve the Strong CP
  Problem?

abstract:
  We find that there are three axions in standard--like superstring models in
the four dimensional free fermionic formulation. These axions are either
harmful or very heavy. Therefore, they cannot solve the strong CP problem. We
show that this is a general result in superstring models with chiral
generations from the $Z_2$ twisted sectors which use a $Z_4$ twist.


title: Effective Field Theories with Instantons

abstract:
  We explain how nonperturbative effects can be systematically included when
constructing an effective field theory. We concentrate in particular on the
matching calculation, by which a low energy theory without a heavy particle
degree of freedom is matched onto the full theory. The matching calculation
requires some new formalism, because for a large class of theories, instantons
occur in a continuous range of scales from far below the mass of the heavy
particle to far above. We show how the complete IR finiteness of the usual
matching formalism arises in this new context. As an example, we formally
integrate out a heavy quark in QCD. %%%% Includes 14 PiCTeX figures. %%%%


title: Precocious Scaling in Antiproton - Proton Scattering at Low Energies

abstract:
  The scaling of the diffraction peak in antiproton--proton scattering has been
investigated from near threshold up to $3\,\,\, GeV/c$ laboratory momenta.It
was shown that the scaling of the differential cross sections are evidentiated
with a surprising accuracy not only at high energies,but also at very low
ones(e.q. $p_{LAB}=0.1--0.5\,\,\, GeV/c$),beyond the resonance and exotic
resonance regions.This precociuos scaling strongly suggests that the s --
channel helicity conservation (SCHC) can be a peculiar property that should be
tested in antiproton -proton interaction not only at high energies but also at
low energy even below $ p_{LAB}
  = 1\,\,\, GeV/c $.


title: Critical Exponents from the Effective Average Action

abstract:
  We compute the critical behaviour of three-dimensional scalar theories using
a new exact non-perturbative evolution equation. Our values for the critical
exponents agree well with previous precision estimates.


title:
Radiative Symmetry Breaking and the Top Quark Mass in Local
  Supersymmetry

abstract:
  Exact low energy expressions are derived for the top-squark and higgs masses,
taking into account radiative contributions due to a heavy top quark. Their
masses are expressed as analytic functions of $m_{1/2}$, $m_{3/2}$, $m_t$ and
$sin\beta$. Constraints from the radiative symmetry breaking mechanism are used
then, to put lower bounds on the top-quark mass $m_t$. In particular, when
$m_{3/2}\gg m_{1/2}$, we obtain the bound $m_t \ge 150sin\beta GeV$, while in
the case of $m_{3/2}\equiv 0$, we obtain $m_t \ge 80sin\beta GeV$.


title: Event shape criteria for single-lepton top signals

abstract:
  Single-lepton plus jets signals from $t\bar t$ production at hadron colliders
generally give more spherically symmetrical events than the principal
backgrounds from $W$ production. We show that sphericity and aplanarity
criteria, applied to lepton plus neutrino plus four jet final states at the
Fermilab Tevatron $p\bar p$ collider, help to discriminate; they can be used
either to validate an eventual top signal or simply to reduce background. An
alternative circularity criterion in the transverse plane is less successful.


title: Spontaneous CP violation in the Supersymmetric Higgs Sector

abstract:
  Spontaneous CP--violation in the minimal supersymmetric standard model with a
gauge singlet and a cubic superpotential is examined. Although the tree--level
Higgs potential conserves CP, it is shown that with the inclusion of the
one--loop top--quark radiative effects, CP may be broken spontaneously. The
CP--violating minimum requires two neutral $(h_1,h_2)$ and one charged
$(H^\pm)$ Higgs--bosons to be relatively light with $m_{h_1}+m_{h_2}
\stackrel{_<}{_\sim} 100~GeV$ and $m_{H^\pm} \stackrel{_<}{_\sim} 110~GeV$. The
electric dipole moment of the electron is in the observable range of $({1 \over
3}~{\rm to}~3) \times 10^{-27}$e-cm.


title:
Alignment in Gamma-Hadron Families Detected by Deep Lead X-Ray Emulsion
  Chambers

abstract:
  Alignment of main fluxes of energy in a target plane is found in families of
cosmic ray particles detected in deep lead X-ray emulsion chambers. The
fraction of aligned events becomes unexpectedly large for superfamilies with
the total energy of gamma-quanta exceeding $10^3$ TeV. This can be considered
as an evidence of existence of coplanar scattering of secondary particles in
interactions of primary particles with superhigh energies ($E_0 \ga 10^{16}$
eV). Data analysis suggests that production of most superfamilies happens low
above the chamber and is characterized by a coplanar scattering and
quasiscaling spectrum of secondary particles in the fragmentation region.


title:
Two New Supersymmetric Options for Two Higgs Doublets at the Electroweak
  Energy Scale

abstract:
  Contrary to common belief, the requirement that supersymmetry exists and that
there are two Higgs doublets and no singlet at the electroweak energy scale
does not necessarily result in the minimal supersymmetric standard model
(MSSM). Two interesting alternatives are presented.


title: Quantum Solitons with Cylindrical Symmetry

abstract:
  Soliton solutions with cylindrical symmetry are investigated within the
nonlinear $\sigma $-model disregarding the Skyrme-stabilization term. The
solitons are stabilized by quantization of collective breathing mode and
collapse in the $\hbar \to 0$ limit. It is shown that for such stabilization
mechanism the model, apart from solitons with integer topological number $B$,
admits the solitons with half-odd $B$. The solitons with integer $B$ have
standard spin-isospin classification, while $B={\ds {1\over 2}}$ solitons are
shown to be characterized by spin, isospin and some additional "momentum".


title:
Polarized Deformed Nuclei Studied via Coincidence Polarized Electron
  Scattering: The case of 21 Ne

abstract:
  Coincidence reactions of the type $\svec{A}(\svec{e},e'N)B$ involving the
scattering of polarized electrons from deformed polarized targets are discussed
within the context of the plane--wave impulse approximation. A general
expression for the polarized spectral function for transitions leaving the
residual nucleus in discrete states is presented. General properties and
angular symmetries exhibited by the polarization observables are discussed in
detail. Results for unpolarized cross sections as well as for polarization
ratios (asymmetries) are obtained for typical quasi--free kinematics. The
dependences of the polarization observables on the bound neutron momentum,
target polarization orientation, nuclear deformation and value of the momentum
transfer $q$ are discussed in detail for various different kinematical
situations.


title:
Regularization Dependence of Running Couplings in Softly Broken
  Supersymmetry

abstract:
  We discuss the dependence of running couplings on the choice of
regularization method in a general softly-broken N=1 supersymmetric theory.
Regularization by dimensional reduction respects supersymmetry, but standard
dimensional regularization does not. We find expressions for the differences
between running couplings in the modified minimal subtraction schemes of these
two regularization methods, to one loop order. We also find the two-loop
renormalization group equations for gaugino masses in both schemes, and discuss
the application of these results to the Minimal Supersymmetric Standard Model.


title: Stability of Two Doublet Electroweak Strings

abstract:
  Vortex solutions in the two Higgs doublet electroweak model are constructed,
and their stability to small perturbations is studied. The most general
perturbation is decomposed into angular momentum modes, the least stable mode
is identified, and the linearised energy change of the vortex under this
perturbation is calculated numerically for various choices of parameters, thus
determining whether or not the string is stable. It is found that, for
realistic values of the Higgs mass and Weinberg angle, the string is unstable.


title: Loop-Induced Majoronic Decay of Neutrinos:

abstract:
  In models where the suppression of the tree level couplings of fermions with
Goldstone bosons is not protected by symmetry, the loop-induced couplings can
in general dominate over the tree couplings. We demonstrate this by calculating
the decay $\nu\to \nu' + \mbox{Majoron}$ in the simplest singlet Majoron model.
It is shown that 1-loop contributions can be orders of magnitude bigger than
the tree-level result, and hence allows a wide range of interesting values of
neutrino mass and mixing to be compatible with cosmological constraints.


title:
Proton Decay and Related Processes in Unified Models with Gauged Baryon
  Number:

abstract:
  In unification models based on SU(15) or SU(16), baryon number is part of the
gauge symmetry, broken spontaneously. In such models, we discuss various
scenarios of important baryon number violating processes like proton decay and
neutron-antineutron oscillation. Our analysis depends on the effective operator
method, and covers many variations of symmetry breaking, including different
intermediate groups and different Higgs boson content. We discuss processes
mediated by gauge bosons and Higgs bosons parallely. We show how accidental
global or discrete symmetries present in the full gauge invariant Lagrangian
restrict baryon number violating processes in these models. In all cases, we
find that baryon number violating interactions are sufficiently suppressed to
allow grand unification at energies much lower than the usual $10^{16}$ GeV.


title:
On a precise calculation of (f_{B_s}/f_B) / (f_{D_s}/f_D) and its
  implications on the interpretation of B - \bar B mixing

abstract:
  We observe that quantities like (f_{B_s}/f_B) / (f_{D_s} /f_D) are predicted
to be unity both by heavy quark and by light quark flavor symmetries. Hence,
the deviation from the symmetry prediction must be simultaneously small in both
symmetry breaking parameters, i.e., order of the ratio of light to heavy quarks
masses. We estimate the size of the correction. We observe that the ratio of
(\Delta M/\Gamma) for B_s - \bar B_s to B - \bar B mixing can be expressed in
terms of the measurable ratio f_{D_s} / f_D with good precision. We comment on
applications of these ideas to other processes.


title: Temperature Dependence of the QCD Coupling

abstract:
  We present a one-loop calculation of a gauge invariant QCD beta function.
Using both momentum and temperature renormalization group equations we
investigate the running coupling in the magnetic sector as a function of
temperature and momentum scale. At fixed momentum scale we find that, in
contrast to $\lambda\phi^4$ or QED, high-temperature QCD is strongly coupled,
even after renormalization group improvement. However, if the momentum scale is
changed simultaneously with temperature in a specified manner, the coupling
decreases. We also point out in what regime dimensional reduction occurs. Both
the cases $N_f$ smaller and larger than $\frac{11}{2} N_c$ are discussed.


title: Hadronic axion, baryogenesis and dark matter

abstract:
  We investigate the prospects of an extra global symmetry, added to the
Standard Model in the context of baryogenesis. The $PQ$ symmetry is studied as
an example. We show that the hadronic axion provides a protection of the
B-asymmetry even if $B-L$=0 and that there are no limits on the neutrino
masses. It is also shown that there is a crucial difference between the two
possible invisible axion models. A connection between the baryon asymmetry and
dark matter is also pointed out.


title:
Non universality of structure functions and measurement of the strange
  sea density

abstract:
  We show that there is no real conflict between the two determinations of the
strange sea density from the opposite--sign dimuon production and from the
difference of the $F_2$ structure functions measured in neutrino and muon deep
inelastic scattering. Once non universal sea parton densities are introduced,
which take into account the effects of different mass thresholds and different
longitudinal contributions, the discrepancy is shown to disappear and both sets
of data are simultaneously well reproduced. No need for a large strange sea
content of the nucleon emerges.


title: Sizing up the Nuclear Glue in $J/\psi$-production

abstract:
  Nuclear gluon densities are of great importance to the physics of
relativistic heavy ion collisions, in particular, in assessing the origin of
$J/\psi$-suppression. We describe our attempts to distinguish various models of
the gluonic EMC-effect, using the existing $J/\psi$-production data in
proton-nucleus collisions. We find that no model is capable of explaining {\em
all} the features of the high precision E772 data although the overall trend
suggests this to be more a matter of fine-tuning the models than the presence
of new physical effects.


title: Factorial Moments in a Generalized Lattice Gas Model

abstract:
  We construct a simple multicomponent lattice gas model in one dimension in
which each site can either be empty or occupied by at most one particle of any
one of $D$ species. Particles interact with a nearest neighbor interaction
which depends on the species involved. This model is capable of reproducing the
relations between factorial moments observed in high--energy scattering
experiments for moderate values of $D$. The factorial moments of the negative
binomial distribution can be obtained exactly in the limit as $D$ becomes
large, and two suitable prescriptions involving randomly drawn nearest neighbor
interactions are given. These results indicate the need for considerable care
in any attempt to extract information regarding possible critical phenomena
from empirical factorial moments.


title: The Nonabelian Debye Mass at Next-to-Leading Order

abstract:
  It is shown that after a resummation of leading high-temperature
contributions, a complete and gauge-independent result for the nonabelian Debye
screening mass at next-to-leading order can be extracted from the static gluon
propagator. In contrast to previous, incomplete results, the correction to the
Debye mass is found to be logarithmically sensitive to the nonperturbative
magnetic mass and positive, in accordance with recent high-statistics results
from lattice calculations.


title: Supersymmetry with Grand Unification

abstract:
  Supersymmetry (SUSY) has many well known attractions, especially in the
context of Grand Unified Theories (GUTs). SUSY stabilizes scalar mass
corrections (the hierarchy problem), greatly reduces the number of free
parameters, facilitates gauge coupling unification, and provides a plausible
candidate for cosmological dark matter. In this conference report we survey
some recent examples of progress in SUSY-GUT applications.


title:
Real Higgs singlet and the electroweak phase transition in the standard
  model, (UM-P-93/80, OZ-93/20)

abstract:
  The effective potential at finite temperature is constructed within the
minimal standard model when a real Higgs singlet is added on. We find that a
region of parameter space exists for which one can find a first order
transition strong enough to prevent the erasure due to sphalerons of baryon
asymmetry, while keeping the mass of the smallest Higgs boson above the
experimental lower bound of about 60 GeV.


title: Phenomenology of Gluino Searches at the Tevatron

abstract:
  Present data indicates that the gluino (if it exists) must be heavier than
about 95~GeV. During the next few years as the Tevatron integrated luminosity
increases, gluino searches will be able to probe the mass range between 100 and
200~GeV. For masses in this range, a variety of gluino decay modes can provide
viable signatures for gluino detection. Apart from the classic missing
transverse energy signal, the detection of high transverse momentum like-sign
dileptons may be the cleanest signature for gluino production. Other signatures
such as the production of a hard photon in the gluino cascade decay may also
play an important role in confirming the supersymmetric origin of events
originating from gluino production and decay.


title: Dynamics of Moving and Spinning Skyrmions

abstract:
  We study the intermediate- and long-range forces between moving and spinning
Skyrmions, employing two different methods. One uses a relativised product
ansatz for the Skyrme fields, the other models Skyrmions as triplets of scalar
dipoles. The methods lead to the same finite-dimensional Lagrangian dynamical
system which may be interpreted as a point-particle approximation to Skyrmion
dynamics. We discuss in detail the dynamics in the so-called attractive channel
and the interaction between well-separated and rapidly spinning Skyrmions, and
point out the resemblance between the latter and the one-pion exchange
potential in nuclear physics.


title:
A Monte Carlo Event Generator for W Off-shell Pair Production including
  Higher Order Electromagnetic Radiative Corrections

abstract:
  We present the Monte Carlo event generator {\tt WOPPER} for pair production
of $W$'s and their decays at high energy $e^+e^-$ colliders. {\tt WOPPER}
includes the effects from finite $W$ width and focusses on the calculation of
higher order electromagnetic corrections in the leading log approximation
including soft photon exponentiation and explicit generation of exclusive hard
photons.


title: Constraints on SUSY Masses in Supersymmetric Grand Unified Theories

abstract:
  Within the Minimal Supersymmetric Grand Unified Theory (MSGUT) masses of the
predicted supersymmetric particles are constrained by the world averaged values
of the electroweak and strong coupling constants, the lower limits on the
proton lifetime,the lower limit on the lifetime of the universe, which implies
an upper limit on the dark matter density, the electroweak symmetry breaking
originating from radiative corrections due to the heavy top quark, and the
ratio of the masses of the b-quark and tau-lepton. A combined fit shows that
indeed the MSGUT model can satisfy all these constraints simultaneously and the
corresponding values for all SUSY masses are given within the minimal model,
taking into account the complete second order renormalisation group equations
for the couplings and the one-loop corrections to the Higgs potential for the
calculation of the Z-mass and the Higgs masses. These one-loop corrections to
MZ have been derived explicitly as function of the stop- and top masses and
found to be small for the best solution, but unnaturally large for the 90% C.L.
upper limits on the SUSY masses.


title: Higgs Search : Present and Future

abstract:
  In this talk I review theoretical bounds on mass of the Higgs scalar in the
Standard Model(SM) and then summarise current experimental limits from the LEP
experiments. Following this I discuss the search strategies for the SM Higgs at
LEP 200 and the TeV energy \eplem\ colliders which are under discussion. This
will be followed by a summary of the Higgs search potential of the pp
supercolliders such as SSC/LHC. I then close with a brief discussion of a `Dark
Higgs' whose dominant decay modes are into invisible channels.


title: Top Quark Physics at Hadron Colliders

abstract:
  I briefly report on what we can learn about the top quark at hadron
colliders.


title: Production, Decay, and Polarization of Excited Heavy Hadrons

abstract:
  We discuss the production via fragmentation of excited heavy mesons and
baryons, and their subsequent decay. In particular, we consider the question of
whether a net polarization of the initial heavy quark may be detected, either
in a polarization of the final ground state or in anisotropies in the decay
products of the excited hadron. The result hinges in part on a nonperturbative
parameter which measures the net transverse alignment of the light degrees of
freedom in the fragmentation process. We use existing data on charmed mesons to
extract this quantity for certain excited mesons. Using this result, we
estimate the polarization retention of charm and bottom baryons.


title: Intermittency in Branching Processes

abstract:
  We study the intermittency properties of two branching processes, one with a
uniform and another with a singular splitting kernel. The asymptotic
intermittency indices, as well as the leading corrections to the asymptotic
linear regime are explicitly computed in an analytic framework. Both models are
found to possess a monofractal spectrum with $\varphi_{q}=q-1$. Relations with
previous results are discussed.


title: Suppression of Bremsstrahlung at Non-Zero Temperature

abstract:
  The first-order bremsstrahlung emission spectrum is $\alpha d\omega/\omega$
at zero temperature. If the radiation is emitted into a region that contains a
thermal distribution of photons, then the rate is increased by a factor
$1+N(\omega)$ where $N(\omega)$ is the Bose-Einstein function. The stimulated
emission changes the spectrum to $\alpha Td\omega/\omega^{2}$ for $\omega\ll
T$. If this were correct, an infinite amount of energy would be radiated in the
low frequency modes. This unphysical result indicates a breakdown of
perturbation theory. The paper computes the bremsstrahlung rate to all orders
of perturbation theory, neglecting the recoil of the charged particle. When the
perturbation series is summed, it has a different low-energy behavior. For
$\omega\ll\alpha T$, the spectrum is independent of $\omega$ and has a value
proportional to $d\omega/\alpha T$ .


title: The Decay $B\to K^*\gamma$ from QCD Sum Rules

abstract:
  Using the QCD sum rules approach and the complete leading--logarithmic
short--distance coefficients determining the penguin--amplitude, we obtain
$B(B\to K^*\gamma) = (6.8\pm 2.4)\cdot 10^{-5}$ for top--quark masses in the
range (150--200) GeV and $|V_{cb}| = 0.035$ for $\tau_B = 1.5\,\text{ps}$. The
ratio to the inclusive rate is $B(B\to K^*\gamma)/B(B\to X_s\gamma) = (20\pm
6)\% $.


title:
Dynamical Properties of Heavy-Ion Collisions from the Photon-Photon
  Intensity Correlations

abstract:
  We consider here the bremsstrahlung emission of photons at low and
intermediate energies $ E_{lab}\le 1000 MeV/u$ of the projectile. and derive
expressions more general than previous results obtained by Neuhauser which were
limited to the case of isotropic systems. We find that the two-photon
correlation function strongly depends not only on the space-time properties of
the collision region but also on the dynamics of the proton-neutron scattering
process in nuclear matter. As a consequence of polarisation correlations it
turns out that for a purely chaotic source the intercept of the correlation
function of photons can reach the value $3$ (as compared with the maximum value
$2$ for isotropic systems). Furthermore even for ``hard" photons ($E_{\gamma} >
25 MeV$) the maximum of the correlation function can reach the value of $2$ in
contrast with the value of $1.5$ derived by Neuhauser for this case. The
formulae obtained in this paper which include also the possible presence of a
coherent component can be used as a basis for a systematic analysis of photon
intensity-interferometry experiments.


title: Inclusive Semileptonic B and Polarized Lambda_b Decays from QCD

abstract:
  The differential decay spectrum $d\Gamma/dE_e dq^2$ for the semileptonic
decay of an unpolarized hadron containing a b-quark, and the decay spectrum
$d\Gamma/dE_e dq^2 d\!\cos\theta$ for polarized $\Lambda_b$ decay are computed
to second order in the $1/m_b$ expansion. Most of the $1/m_b^2$ corrections
have a simple physical interpretation, which is discussed in detail. The
implications of the results for the determination of $V_{ub}$ are discussed.
The decay spectra for semileptonic decay of hadrons containing a c-quark are
also given. There is a subtlety in the use of the equations of motion at order
$1/m_b^2$ in the heavy quark expansion which is explained.


title: Positronium Spectroscopy in a Magnetic Field

abstract:
  Hyperfine spectroscopy of positronium formed in the presence of a static
magnetic field is considered. Generalising the situation hitherto developed in
the literature, the magnetic field is not assumed to be parallel to the
momentum of incoming polarised positrons, while the possibility of electron
polarisation is also included in the analysis. The results are of application
to high sensitivity positron polarimeters used in current $\beta$ decay
experiments.