title: SUSY-GUT Higgs Probe at Future $e^+e^-$ Colliders

abstract:
  Several independent constraints on the minimal supersymmetric model with
constraints from grand unifications and cosmology select the region of
low-energy supersymmetry below ${\cal O}$(1~TeV). The resulting mass of the
lightest Higgs boson can probably be covered at LEP II only if its beam energy
exceeds 200~GeV, and is within the detectability range of the NLC with
$\sqrt{s}=300$~GeV.


title:
Constraints on spin-3/2 and excited spin-1/2 fermions coming from the
  leptonic Z0-partial width

abstract:
  We consider effective interactions among excited spin-1/2 and spin-3/2
leptons with the usual ones. Assuming that these new leptons are lighter than
the Z0 we will study the constraints on their masses and compositeness scale
coming from the leptonic Z0 partial width.


title:
Consistent Calculation of the Nucleon Electromagnetic Polarizabilities
  in Chiral Perturbation Theory Beyond Next-to-Leading Order

abstract:
  We calculate the nucleons' electromagnetic polarizabilities in heavy baryon
chiral perturbation theory including all terms to order ${\cal O} (q^4)$. The
chiral prediction of the electric polarizabilities for the neutron and the
proton are in good agreement with the data. In the case of the magnetic
polarizabilities the big positive contribution from the $\Delta(1232)$
resonance is largely cancelled by a non--analytic loop contribution of the $\ln
M_\pi$ type. This novel effect helps to understand the rather small empirical
value of the nucleons' magnetic polarizability.


title:
Probing $WW\gamma$ Couplings from $\sigma_{tot}(W)/\sigma_{tot}(Z)$ 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:
Rapidity Distributions of Dileptons from a Hadronizing Quark-Gluon
  Plasma

abstract:
  It has been predicted that dilepton production may be used as a quark-gluon
plasma probe. We calculate the rapidity distributions of thermal dileptons
produced by an evolving quark-gluon plasma assuming a longitudinal scaling
expansion with initial conditions locally determined from the hadronic rapidity
density. These distributions are compared with Drell-Yan production and
semileptonic charm decays at invariant mass $M = 2$, 4, and 6 GeV.


title: The KeV Majoron as Dark Matter Particle

abstract:
  We consider a very weakly interacting KeV majoron as dark matter particle
(DMP), which provides both the critical density $\rho_{cr} = 1.88 \times
10^{-29} h^{2}$ $g/cm^{3}$ and the galactic scale $M_{gal}$ $\sim
m^{3}_{Pl}/m^{2}_{J} \sim 10^{12} M_{\odot} (m_{J}/1 KeV)^{-2}$ for galaxy
formation. The majoron couples to leptons only through some new "directly
interacting particles", called DIPS, and this provides the required smallness
of the coupling constants. If the masses of these DIPS are greater than the
scale $V_s$ characterizing the spontaneous violation of the global lepton
symmetry they are absent at the corresponding phase transition ($T \sim V_s$)
and the majorons are produced during the phase transition, never being in
thermal equilibrium during the history of the universe. In the alternative case
$m_{DIP} < V_{s}$ the majorons can be for a short period in thermal
equilibrium. This scenario is not forbidden by nucleosynthesis and gives a
reasonable growth factor for the density fluctuations compatible with COBE. A
possible signature is an X-ray line at $E_\gamma = \frac{m_J}{2}$, produced by
the decay $J \to \gamma + \gamma$. A model is described which realizes the
possibility of the KeV majoron as DMP and may also lead to observable rates for
decays such as $\mu \ra e \gamma$ and $\mu \ra 3e$.


title:
Improving the Effective Potential, Multi-Mass Problem and Modified
  Mass-Dependent Scheme

abstract:
  We present a new procedure for improving the effective potential by using
renormalization group equation (RGE) in the presence of several mass scales. We
propose a modification of the mass-dependent (MD) renormalization scheme, MDbar
scheme, so that the scalar mass parameter runs at most logarithmically on the
one hand and the decoupling of heavy particles is naturally incorporated in the
RGE's on the other. Thanks to these properties, the procedure in MDbar scheme
turns out to be very simple compared with the regionwise procedure in MSbar
scheme proposed previously. The relation with other schemes is also discussed
both analytically and numerically.


title: Detecting an Invisibly Decaying Higgs Boson at a Hadron Supercollider

abstract:
  We demonstrate that an invisibly decaying Higgs boson with Standard Model
coupling strength to top--anti-top can be detected at the LHC for masses up to
about 250 GeV.


title: Instanton contributions to the $\tau$ decay widths

abstract:
  Contrary to some previous claims, we find a sizable instanton contribution to
the finite energy sum rule used to extract the value of the strong coupling
from the measured $\tau$ decay widths. It is of the same order of magnitude as
standard nonperturbative corrections induced by vacuum quark and gluon
condensates. Our result indicates that there might be no hierarchy of power
corrections in finite energy sum rules at the scale of $\tau$ mass. Therefore,
the standard nonperturbative corrections do not necessarily improve the
accuracy of the theoretical predicition, but can rather be used to estimate an
intrinsic accuracy of the pure perturbative calculation, which turns out to be
rather high on this evidence, of order one percent.


title: On the Neutralino as Dark Matter Candidate - I. Relic Abundance

abstract:
  The neutralino relic abundance is evaluated for a wide range of the
neutralino mass, ${\rm 20\ GeV} \leq m_\chi \leq {\rm 1\ TeV}$, by taking into
account the full set of final states in the neutralino-neutralino annihilation.
The analysis is performed in the Minimal SuSy Standard Model; it is not
restricted by stringent GUT assumptions but only constrained by present
experimental bounds. We also discuss phenomenological aspects which are
employed in the companion paper (II. Direct Detection) where the chances for a
successful search for dark matter neutralino are investigated.


title: On the Neutralino as Dark Matter Candidate - II. Direct Detection

abstract:
  Evaluations of the event rates relevant to direct search for dark matter
neutralino are presented for a wide range of neutralino masses and for various
detector materials of preeminent interest. Differential and total rates are
appropriately weighted over the local neutralino density expected on
theoretical grounds.


title: Vector and Scalar Meson Resonances in $K\rightarrow\pi\pi\pi$ Decays

abstract:
  Corrections to $K\rightarrow\pi\pi\pi$ induced by vector and scalar meson
exchange are investigated within chiral perturbation theory.


title: Some consequences of the effective low-energy lagrangian for gravity

abstract:
  We consider the minimal low-energy action for gravity up to six derivatives
which is renormalizable at the two-loop level modulo higher derivative
corrections. Then we study the classical solutions corresponding to the
Schwarzschild and the Robertson-Walker metrics. In the first case we find a
singularity close to the gravitational radius and in the second case we find
inflationary de Sitter solutions in absence of any matter or cosmological
constant.


title: Review of Z' Constraints

abstract:
  We review present Z' bounds, discuss future Z' constraints from TEVATRON,
HERA and LEP, and give a brief review of the Z' diagnostics at future
colliders.


title: Renormalization of the Neutrino Mass Operator

abstract:
  A small neutrino Majorana mass can arise in the Standard Model as an
effective dimension 5 operator. We calculate the renormalization of this
operator in the minimal Standard Model and in its two-Higgs-doublet and
supersymmetric extensions. Renormalization from the scale of lepton number
violation (e.g., the Planck scale or a GUT scale) to the weak scale decreases
the strength of this operator by an order of magnitude or more if the top quark
and Higgs boson masses are large. Neutrino mixing angles also run with
momentum. We show instances where small mixing at a high scale becomes large at
the weak scale, and vice versa.


title: Vertices and the CJT Effective Potential

abstract:
  The Cornwall-Jackiw-Tomboulis effective potential is modified to include a
functional dependence on the fermion-gauge particle vertex, and applied to a
quark confining model of chiral symmetry breaking.


title: Damping Rate of a Fermion in a Medium

abstract:
  We examine the relation between the damping rate of a massless, chiral
fermion that propagates in a medium, and the rate $\Gamma$ of approach to
equilibrium. It is proven that these quantities are equal, by showing that they
are given by the same formula in terms of the imaginary part of the self-energy
evaluated at the energy of the propagating fermion mode. This result is valid
provided $\Gamma$ is defined by using the appropriate wave functions of the
mode.


title: Higgs Sector Motivations for an e-minus e-minus Linear Collider

abstract:
  I briefly review the crucial role an $\emem$ linear collider could play in
unravelling the nature of a non-minimal Higgs sector and/or
strongly-interacting $WW$ sector.


title: Measuring Three Vector Boson Couplings in $qq\to qqW$ at the SSC

abstract:
  We investigate the electroweak process $qq\to qqW$, {\it i.e.} $W$ production
via $W\gamma$ and $WZ$ fusion, as a probe for nonstandard $WW\gamma$ and $WWZ$
vertices at hadron supercolliders. Triggering on events with one very forward
and one very backward jet while requiring the $W$ decay lepton to be central,
strongly enhances the triple gauge boson vertex contribution and suppresses
backgrounds from QCD $Wjj$ events and $t\bar tj$ production below the signal
level. At the SSC, the process is sensitive to $WWV$, $V=\gamma\, ,Z$ couplings
$\kappa_V -1$, $\lambda_V$, and $g_1^Z$ in the $0.03\dots 0.1$ range.


title:
Constraints on the anomalous $WW\gamma$ couplings from $b\rightarrow
  s\gamma$

abstract:
  We study contributions to $b \rightarrow s \gamma$ from anomalous $WW\gamma$
interactions. Although these anomalous interactions are not renormalizable, the
contributions are cut-off independent. Using recent results from the CLEO
collaboration on inclusive radiative B decays, we obtain bounds for the
anomalous CP conserving and CP violating couplings. The constraints on the CP
conserving couplings are comparable with or better than constraints from other
experiments.


title:
The Low-Energy Theorem of Pion Photoproduction in Soliton Models of the
  Nucleon

abstract:
  We derive an analytic expression for the Kroll-Ruderman amplitude up to the
order 1/N_C for general Skyrme-type models of the nucleon. Due to the
degeneracy of intermediate N- and Delta-states we find deviations from the
standard low-energy theorem for the photoproduction of neutral pions.


title: Semileptonic Decays and CKM Matrix Elements in a TCF

abstract:
  We argue that a Tau-Charm factory (TCF) could improve our knowledge of CKM
matrix elements since it is an incomparable tool to check the models and
methods applied to extract $V_{bu}$ from $B$ decay partial widths.
  We report on some recent proposals to improve on parton model. Turning to
exclusive decays, we compare the predictions from quark models, QCD sum rules,
effective Lagrangians and lattice QCD. Quark models have anticipated on heavy
quark symmetry. Their difficutly to account for the $q^2$ dependence might be
partly cured by relativistic corrections. QCD sum rules and lattice seem to
disagree on the $q^2$ dependence of axial form factors. We discuss the
extrapolation from $D$ to $B$. Present uncertainties do not allow to predict
reliably the $B\ra\pi,\rho l \nu$ matrix elements. We argue that QCD sum rules
are in a good position to study $q^2$ dependence down to $q^2=0$. Lattice QCD
is able to check the heavy quark scaling laws for the heavy to light
semileptonic decays. It seems to confirm the increase of $A_2/A_1$ from $D$ to
$B$ meson predicted by the scaling laws. Finally semileptonic decays in a TCF
would give incomparable informations on $K\pi$ phase shifts, and on $K^{**}$
resonances.


title: Effects of Amplitude Nullification in the Standard Model

abstract:
  Delicate cancellations among diagrams can result in the vanishing of
threshold amplitudes in the standard model. This phenomenon is investigated for
multi-Higgs production by scalar, vector, and fermionic fields. A surprising
gap is found where although the tree-level amplitude for $2$ incoming gauge
bosons to produce $N_v$ particle may vanish, the amplitude for the production
of $N_{v}+1$ particles is nonzero.


title: Direct Instantons in QCD Nucleon Sum Rules

abstract:
  We study the role of direct (i.e. small-scale) instantons in QCD correlation
functions for the nucleon. They generate sizeable, nonperturbative corrections
to the conventional operator product expansion, which improve the quality of
both QCD nucleon sum rules and cure the long-standing stability problem, in
particular, of the chirally odd sum-rule.


title:
Effects of new physics to the the $\rho$--parameter in the
  supersymmetric standard model

abstract:
  The contribution to the $\rho$--parameter of the quark--Higgs sector of the
supersymmetric standard model is computed non--perturbatively using the
large--$\nf$ expansion for the case tan$\beta$=0. An explicit formula is found
for the $\rho$--parameter which is ill-defined unless the triviality cutoff is
taken into account. The cutoff dependence of the $\rho$--parameter is found to
be large if and only if the top mass is larger than $2v$ so that the cutoff
scale is of the order of the electroweak scale. These non--universal effects
are the reflections at low energies of the physics beyond the supersymmetric
standard model. By also considering the effects of the soft--breaking terms,
cutoff effects in both decoupling and non--decoupling effects are analyzed.


title:
How suppressed are the radiative interference effects in heavy unstable
  particle production?

abstract:
  We present a \lq\lq theorem" which quantifies, for inclusive processes, the
level of suppression of the radiative interference effects between the
production and decay stages of heavy {\it unstable} particles. The theorem,
which is based on very general physical arguments, is applicable to all orders
in the coupling.


title: Observing Disoriented Chiral Condensates

abstract:
  We speculate that, in very high energy hadronic collisions, large fireballs
may be produced with interiors which have anomalous chiral order parameters.
Such a process would result in radiation of pions with distinctive momentum and
isospin distributions, and may provide an explanation of Centauro and related
phenomena in cosmic-ray events. The phenomenology of such events is reviewed,
with emphasis on the possibility of observing such phenomena at Fermilab
experiment T-864 (MiniMax), or at a Full Acceptance Detector (FAD) at the SSC.


title: On The Dimensional Methods in Rare b Decays

abstract:
  Since several years there exists a question whether the dimensional reduction
and the usual dimensional regularization give different results for the
QCD-improved $b \rightarrow s \gamma$ and $b \rightarrow s$ $gluon$ decay
rates. Here it is demonstrated explicitly that this is not the case: As long as
physically meaningful quantities are considered, the results obtained with help
of both techniques agree.


title: Catalyzed decay of false vacuum in four dimensions

abstract:
  The probability of destruction of a metastable vacuum state by the field of a
highly virtual particle with energy $E$ is calculated for a (3+1) dimensional
theory in the leading WKB approximation in the thin-wall limit. It is found
that the induced nucleation rate of bubbles, capable of expansion, is
exponentially small at any energy. The negative exponential power in the rate
reaches its maximum at the energy, corresponding to the top of the barrier in
the bubble energy, where it is a finite fraction of the same power in the
probability of the spontaneous decay of the false vacuum, i.e. at $E=0$.


title: Dynamics of Cosmological Phase Transitions

abstract:
  The dynamics of typical phase transitions is studied out of equilibrium in
weakly coupled inflaton-type scalar field theories in Minkowski space. The
shortcomings of the effective potential and equilibrium descriptions are
pointed out. A case of a rapid supercooling from $T_i>T_c$ to $T_f \ll T_c$ is
considered.
  The equations of motion up to one-loop for the order parameter are obtained
and integrated for the case of ``slow rollover initial conditions''. It is
shown that the instabilities responsible for the process of phase separation
introduce dramatic corrections to the evolution. Domain formation and growth
(spinodal decomposition) is studied in a non-perturbative self-consistent
approximation.
  For very weakly coupled theories domains grow for a long time, their final
size is several times the zero temperature correlation length. For strongly
coupled theories the final size of the domains is comparable to the zero
temperature correlation length and the transition proceeds faster. We also
obtain the evolution equations for the order parameter and the fluctuations to
one-loop order and in a non-perturbative Hartree approximation in spatially
flat FRW cosmologies. The renormalization, and leading behavior of the high
temperature limit are analyzed.


title: Signals of Unconventional E$_6$ Models at $e^+e^-$ Colliders

abstract:
  Generation dependent discrete symmetries often appear in models derived from
superstring theories. In particular, in the framework of E$_6$ models the
presence of such symmetries is required in order to allow for the radiative
generation of naturally small neutrino masses. Recently it was shown that by
imposing suitable generation dependent discrete symmetries, a class of models
can be consistently constructed in which the three sets of known fermions in
each generation do not have the same assignments with respect to the {\bf 27}
representation of E$_6$. In this scenario, the different embedding in the gauge
group of the three generations implies in particular that the known charged
leptons couple in a non--universal way to the new neutral gauge bosons
$(Z_\beta)$ present in these models. We exploit this fact to study the
signature of this class of models at present and future $e^+e^-$ colliders. We
show that some signals of deviation from lepton universality as well as some
other discrepancies with the standard model predictions which have been
observed at the TRISTAN collider in the production rate of $\mu$ and $\tau$,
can be accounted for if the $Z_\beta$ mass is not much heavier than 300 GeV. We
also study the discovery limits for lepton universality violation of this type
at LEP-2 and at the 500 GeV $e^+e^-$ Next Linear Collider (NLC). We show that
models predicting unconventional assignments for the leptons will give an
unmistakable signature, when the $Z_\beta$ mass is as heavy as $\sim 800$ GeV
(LEP-2) and $\sim 2$ TeV (NLC).


title: Approximate Flavor Symmetries in the Lepton Sector

abstract:
  Approximate flavor symmetries in the quark sector have been used as a handle
on physics beyond the Standard Model. Due to the great interest in neutrino
masses and mixings and the wealth of existing and proposed neutrino experiments
it is important to extend this analysis to the leptonic sector. We show that in
the see-saw mechanism, the neutrino masses and mixing angles do not depend on
the details of the right-handed neutrino flavor symmetry breaking, and are
related by a simple formula. We propose several ans\"{a}tze which relate
different flavor symmetry breaking parameters and find that the MSW solution to
the solar neutrino problem is always easily fit. Further, the $\nu_\mu -
\nu_\tau$ oscillation is unlikely to solve the atmospheric neutrino problem
and, if we fix the neutrino mass scale by the MSW solution, the neutrino masses
are found to be too small to close the Universe.


title:
$b \rightarrow s \gamma$ and $Z \rightarrow b \overline b$ Constraints
  on Two Higgs Doublet Model

abstract:
  We perform a combined analysis of two stringent constraints on two Higgs
doublet model, coming from the recently announced CLEO II bound on $B(b
\rightarrow s \gamma)$ and $Z \rightarrow b \overline b$ and from the recent
LEP data on the ratio $\Gamma(Z\rightarrow b\overline
b)\over{\Gamma(Z\rightarrow hadrons)}$. We include one-loop vertex corrections
to $Z \rightarrow b \overline b$ in the model. We find that although the CLEO
II bound serves as the strongest constraint present in the charged Higgs sector
of the model, the current LEP value for $R_b$ may also provide a further
constraint for $\tan\beta<1$.


title: Bubble Growth as a Detonation

abstract:
  Bubble growth as a detonation is studied in the context of cosmological phase
transitions. It is proved that the so called Chapman-Jouguet hypothesis, which
restricts the types of detonations that can occur in spherically symmetric
chemical burning, does not hold in the case of phase transitions. Therefore a
much larger class of detonation solutions exists in phase transitions than in
chemical burning.


title: Single Leptoquark Production

abstract:
  The single production of leptoquarks in $e^+e^-$, $e\gamma$ and $\gamma
\gamma$ linear colliders is discussed. We show that these new particles could
be seen in such machines even if their mass is close to the kinematic limit.
(Invited talk given by G.B. at the ``Workshop on Physics and Experiments at
Linear $e^+e^-$ Colliders'', Waikoloa, Hawaii, April 26-30, 1993.)


title: THE $t\bar t\gamma$ BACKGROUND TO $pp\rightarrow W\gamma + X$ AT THE SSC

abstract:
  We calculate the $pp\rightarrow t\bar t\gamma+X\rightarrow W\gamma + X$ cross
section at SSC energies. Approximately 40\% of the total cross section
originates from photon bremsstrahlung off the final state jet in $t\bar tj$
production. Without cuts restricting the hadronic activity, the $t\bar t\gamma$
rate is a factor 10 (2) larger than the tree level $W\gamma$ cross section for
a top quark mass of 110~GeV (200~GeV). Imposing a jet veto cut, the $t\bar
t\gamma$ rate can be suppressed to a level well below the $W\gamma+0$~jet
signal cross section.


title:
Two-loop renormalization group analysis of hadronic decays of a charged
  Higgs boson

abstract:
  We calculate next-to-leading QCD corrections to the decay $H^+ \to u\bar d$
for generic up and down quarks in the final state. A recently developed
algorithm for evaluation of massive two-loop Feynman diagrams is employed to
calculate renormalization constants of the charged Higgs boson. The origin and
summation of large logarithmic corrections to the decay rate of the top quark
into a lighter charged Higgs boson is also explained.


title: Light Gluinos in Four-Jet Events at LEP

abstract:
  The light gluino hypothesis can explain the apparent incompatibility between
the measurements of $\as$ at low- and high-energy. Such gluinos are produced
directlyin four-jet events, for which we perform a detailed analysis. Because
the jet energies are not large, the effect of the non-zero gluino mass is
important. We take the gluino mass into account in the computation of the cross
sections and shape variables. As expected, we find that mass effects tend to
reduce the impact of the gluinos in the cross section, weakening the bounds
from obtaining assuming massless gluinos.


title: Annihilation Diagrams in Two-Body Nonleptonic Decays of Charmed Mesons

abstract:
  In the pole-dominance model for the two-body nonleptonic decays of charmed
mesons $D \rightarrow PV$ and $D \rightarrow VV$, it is shown that the
contributions of the intermediate pseudoscalar and the axial-vector meson poles
cancel each other in the annihilation diagrams in the chiral limit. In the same
limit, the annihilation diagrams for the $D \rightarrow PP$ decays vanish
independently.


title: Probing the Scalar Sector in $e^+ e^- \rightarrow f \bar{f} H$

abstract:
  We study possible deviations from the Standard Model in the reaction $e^+e^-
\to Z\phi$, where $\phi$ denotes a spinless neutral boson. We show how the $Z$
decay angular correlation can be used to extract detailed information on the
$\phi$ couplings, such as the parity of $\phi$, radiatively induced form factor
effects and possible CP violation in the scalar sector. Consequences of gauge
invariant dimension six operators are discussed as an example.


title: A Solution to the Small Phase Problem of Supersymmetry

abstract:
  It is a well--known problem that in supersymmetric models there are new
CP--violating phases which, if unsuppressed, would give a neutron electric
dipole moment $10^2$ to $10^3$ times the present experimental limit. Here we
propose that these new phases are suppressed by CP invariance, which is broken
spontaneously at a high scale and that this breaking shows up at low energies
only through a universal phase of the gaugino masses. It is shown that this can
well fit both $\epsilon$ and $\epsilon^\prime$ of the neutral Kaon system. The
electric dipole moments of the neutron and the electron should be not much
below present limits. A model incorporating these ideas in a very economical
way is presented.


title: Collider Physics 1993

abstract:
  These lectures survey the present situation and future prospects in selected
areas of particle physics phenomenology: (1) the top quark, (2) the Higgs boson
in the Standard Model, (3) strong $WW$ scattering, (4) supersymmetry, (5) the
Higgs sector in minimal supersymmetry, and (6) low-energy constraints on
supersymmetry.


title: Zeroing in on more photons and gluons

abstract:
  We discuss radiation zeros that are found in gauge tree amplitudes for
processes involving multi-photon emission. Previous results are clarified by
examples and by further elaboration. The conditions under which such amplitude
zeros occur are identical in form to those for the single-photon zeros, and all
radiated photons must travel parallel to each other. Any other neutral particle
likewise must be massless (e.g. gluon) and travel in that common direction. The
relevance to questions like gluon jet identification and computational checks
is considered. We use examples to show how certain multi-photon amplitudes
evade the zeros, and to demonstrate the connection to a more general result,
the decoupling of an external electromagnetic plane wave in the ``null zone".
Brief comments are made about zeros associated with other gauge-boson emission.


title:
Testing Supergravity Grand Unification at Future Accelerator and
  Underground Experiments

abstract:
  The full parameter space of supergravity grand unified theory with $SU(5)$
type $p \rightarrow \bar{\nu} K$ proton decay is analysed using renormalization
group induced electroweak symmetry breaking under the restrictions that the
universal scalar mass $m_o$ and gluino mass are $\leq 1$ TeV (no extreme fine
tuning) and the Higgs triplet mass obeys $M_{H_3}/M_G < 10$. Future proton
decay experiments at SuperKamiokande or ICARUS can reach a sensitivity for the
$\bar{\nu} K$ mode of $(2-5) \times 10^{33}$ yr allowing a number of
predictions concerning the SUSY mass spectrum. Thus either the $p
\rightarrow\bar{\nu} K$ decay mode will be seen at these experiments or a
chargino of mass $m_{\tilde{W}} < 100$ GeV will exist and hence be observable
at LEP2. Further, if $(p \rightarrow \bar{\nu} K) > 1.5 \times 10^{33}$ yr,
then either the light Higgs has mass $m_h \leq 95$ GeV or $m_{\tilde{W}} \leq
100$ GeV i.e. either the light Higgs or the light chargino (or both) would be
observable at LEP2. Thus, the combination of future accelerator and future
underground experiments allow for strong experimental tests of this theory.


title:
Braaten-Pisarski Action, Disoriented Chiral Condensate, and Chiral
  Symmetry Non-Restoration

abstract:
  The QCD effective action at high T shows a manifest global chiral symmetry.
And calculations show that the order parameter \psibarpsi vanishes above T_c.
It has been popular to refer to this T_c as chiral symmetry restoration
temperature because it fits into our prejudice that chiral symmetry is like an
`ordered' state, and at high T it must become disordered. In fact, NJL ground
state is not an ordered spin state. The recent scenario of a generic class of
disoriented chiral condensate offers an example where \psibarpsi in each little
domain is nonzero, but the average over all space of \psibarpsi vanishes. Such
a dcc ground state continues to break chiral invariance. But how do you
reconcile this with the apparent chiral symmetry at high T? The
Braaten-Pisarski action is a good laboratory to investigate the subtleties of
high temperature chiral symmetry. By carrying out a canonical quantization of
this highly nonlocal action, I demonstrate how the thermal vacuum at high T
conserves the new \beta-chirality but breaks the old T=0 chirality. Lattice
calculations show that the pion develops a screening mass at high T. Our
continuum field theory calculations show that the QCD pion remains massless for
all T. I conclude the talk by showing how the hot pion manages to accomodate
the two results by propagating in the early universe with a halo.


title:
On-shell Supersymmetry Anomalies and the Spontaneous Breaking of Gauge
  Symmetry

abstract:
  A search for supersymmetry anomalies requires an examination of the BRS
cohomology of supersymmetric Yang-Mills coupled to chiral matter, and the
physically interesting (on-shell) anomalies are those which cannot be
eliminated using the equations of motion. An analysis of this cohomology
problem shows that the simplest situation where a physically interesting
supersymmetry anomaly can arise is when: 1. the anomaly occurs in the
renormalization of a composite antichiral spinor superfield operator
constructed from the chiral matter in the theory, 2. the anomalous diagrams are
one-loop triangle diagrams containing a gauge propagator, 3. the gauge symmetry
(but not supersymmetry) is spontaneously broken, 4. the initial operator has a
dimension such that the triangle diagram is at least linearly divergent, 5. the
anomaly contains only massless chiral superfields, although (apparently harder
to calculate) supersymmetry anomalies can also contain massive chiral
superfields, 6. the theory contains vertices which, after gauge symmetry
breaking, couple massless matter fields to massive matter fields and massive
gauge fields, like the $ e^- \n_e W^+$ vertices of the standard model.
  The supersymmetry anomalies considered here are all `soft', in the sense that
they must vanish when certain masses go to zero. It appears that the order
parameter of the resulting supersymmetry breaking may be the vacuum expectation
value that breaks the gauge symmetry. Nonzero values for the anomalies, if they
exist, appear to generate supersymmetry breaking for observable particles with
a cosmological constant that is naturally zero.


title: Photoproduction Cross Sections at HERA Energies

abstract:
  We show that photoproduction cross sections recently measured by ZEUS and H-1
at HERA energies$^1$ are in agreement with our earlier prediction based on
high-energy hadronic structure of the photon in the QCD minijet-type model$^2$.
We present results of an improved calculation of the photoproduction cross
section, in which the soft part, motivated by the Regge theory, is taken to be
energy-dependent and the semi-hard hadronic part is carefully eikonalized to
take into account for the multiple scatterings and to include the appropriate
probability that photon would act hadronicaly$^3$. We also show that the
extrapolation of our cross section to ultra-high energies, of relevance to the
cosmic ray physics, gives significant contribution to the ``conventional''
value, but cannot account for the anomalous muon content observed in the cosmic
ray air-showers associated with astrophysical point sources$^4$.


title: Star Integrals and Unbiased Estimators

abstract:
  We review in brief the development and implementation of the Star integral, a
tool yielding measurements of correlations much superior to conventional
methods. A version for use in pion interferometry is explained. We also show
how effects of non-poissonian overall multiplicity distributions may be
eliminated if desired and quote results eliminating statistical biases arising
in correlation measurements within small samples.


title: High Temperature Phase Transitions without Infrared Divergences

abstract: Resubmitted due to LATEXing problems


title: Planck-Scale Unification and Dynamical Symmetry Breaking

abstract:
  We explore the possibility of unification of gauge couplings near the Planck
scale in models of extended technicolor. We observe that models of the form G X
SU(3)_c X SU(2)_L X U(1)_Y cannot be realized, due to the presence of massless
neutral Goldstone bosons (axions) and light charged pseudo-Goldstone bosons;
thus, unification of the known forces near the Planck scale cannot be achieved.
The next simplest possibility, G X SU(4)_{PS} X SU(2)_L X U(1)_{T_{3R}}, cannot
lead to unification of the Pati-Salam and weak gauge groups near the Planck
scale. However, superstring theory provides relations between couplings at the
Planck scale without the need for an underlying grand-unified gauge group,
which allows unification of the SU(4)$_{PS}$ and SU(2)$_L$ couplings.


title: Phenomenology of Multi-W Processes in Cosmic Rays

abstract:
  We report on a study of the potential of various cosmic ray physics
experiments to search for Standard Model processes involving the
nonperturbative production of O(30) weak gauge bosons. Whereas present and
near-future experiments are insensitive to proton-induced processes,
neutrino-induced processes give rise to promising signatures and rates in
AMANDA, DUMAND, MACRO and NESTOR provided that a cosmic neutrino flux exists at
levels suggested by recent models of active galactic nuclei. The Fly's Eye
currently constrains the largest region of parameter space characterizing
multi-W phenomena.


title: Leptonic Decay Constants of Charm and Beauty Mesons in QCD: An Update

abstract:
  An update is given of the determination of leptonic decay constants of charm
and beauty mesons in the framework of relativistic Hilbert moments and Laplace
transform QCD sum rules.


title: Existence of Double Vortex Solutions

abstract:
  We show analytically and numerically the existence of double vortex solutions
in two-Higgs systems. These solutions are generalizations of the \no vortices
and exist for all values of the parameters in the Lagrangians considered.
  We derive analytically the asymptotic behavior of the solutions and confirm
it numerically by solving the field equations.
  Finally, we show that these solutions can be embedded in realistic theories
like the two-doublet extension of the standard model.


title: Making the small oblique parameters large

abstract:
  We compute the oblique parameters, including the three new parameters $ V $,
$ W $ and $ X $ introduced recently by the Montreal group, for the case of one
scalar multiplet of arbitrary weak isospin $ J $ and weak hypercharge $ Y $. We
show that, when the masses of the heaviest and lightest components of the
multiplet remain constant, but $ J $ increases, the oblique parameter $ U $ and
the three new oblique parameters increase like $ J^3 $, while $ T $ only
increases like $ J $. For large multiplets with masses not much higher than $
m_Z $, the oblique parameters $ U $ and $ V $ may become much larger than $ T $
and $ S $.


title:
Dynamical chiral symmetry breaking and confinement with an
  infrared-vanishing gluon propagator?

abstract:
  We study a model Dyson-Schwinger equation for the quark propagator closed
using an {\it Ansatz} for the gluon propagator of the form \mbox{$D(q) \sim
q^2/[(q^2)^2 + b^4]$} and two {\it Ans\"{a}tze} for the quark-gluon vertex: the
minimal Ball-Chiu and the modified form suggested by Curtis and Pennington.
Using the quark condensate as an order parameter, we find that there is a
critical value of $b=b_c$ such that the model does not support dynamical chiral
symmetry breaking for $b>b_c$. We discuss and apply a confinement test which
suggests that, for all values of $b$, the quark propagator in the model {\bf is
not} confining. Together these results suggest that this Ansatz for the gluon
propagator is inadequate as a model since it does not yield the expected
behaviour of QCD.


title: Criticality, Fractality and Intermittency in Strong Interactions

abstract:
  Assuming a second-order phase transition for the hadronization process, we
attempt to associate intermittency patterns in high-energy hadronic collisions
to fractal structures in configuration space and corresponding intermittency
indices to the isothermal critical exponent at the transition temperature. In
this approach, the most general multidimensional intermittency pattern,
associated to a second-order phase transition of the strongly interacting
system, is determined, and its relevance to present and future experiments is
discussed.


title: Quark and Pole Models of Nonleptonic Decays of Charmed Baryons

abstract:
  Quark and pole models of nonleptonic decays of charmed baryons are analysed
from the point of view of their symmetry properties. The symmetry structure of
the parity conserving amplitudes that corresponds to the contribution of the
ground-state intermediate baryons is shown to differ from the one hitherto
employed in the symmetry approach. It is pointed out that the "subtraction" of
sea quark effects in hyperon decays leads to an estimate of $W$-exchange
contributions in charmed baryon decays that is significantly smaller than
naively expected on the basis of $SU(4)$. An $SU(2)_{W}$ constraint questioning
the reliability of the factorization technique is exhibited. Finally, a
successful fit to the available data is presented.


title: A Comprehensive Study of Leptoquark Bounds

abstract:
  We make a comprehensive study of indirect bounds on scalar leptoquarks that
couple chirally and diagonally to the first generation by examining available
data from low energy experiments as well as from high energy e+ e- and p pbar
accelerators. The strongest bounds turn out to arise from low energy data: For
leptoquarks that couple to right--handed quarks, the most stringent bound comes
from atomic parity violation. For leptoquarks that couple to left--handed
quarks, there are two mass regions: At low masses the bounds arise from atomic
parity violation or from universality in leptonic pi decays. At masses above a
few hundred GeV's, the dominant bounds come from the FCNC processes that are
unavoidable in these leptoquarks: The FCNC bound of the up sector, that arises
from D-Dbar mixing, combines with the FCNC bounds from the down sector, that
arise from rare K decays and K-Kbar mixing, to a bound on the flavour
CONSERVING coupling to the first generation.
  The bounds restrict leptoquarks that couple with electromagnetic strength to
lie above 600 GeV or 630 GeV for leptoquarks that couple to RH quarks, and
above 1040 GeV, 440 GeV, and 750 GeV for the SU(2)_W scalar, doublet and
triplet leptoquarks that couple to LH quarks. These bounds are considerably
stronger than the first results from the direct searches at HERA. Our bounds
also already exclude large regions in the parameter space that could be
examined by various methods proposed for indirect leptoquark searches.


title:
Relativistic Two-Body Bound-State Calculations Beyond the Ladder
  Approximation

abstract:
  In this work the Feynman-Schwinger representation for the two-body Greens
function is studied. After having given a brief introduction to the formalism,
we report on the first calculations based on this formalism. In order to
demonstrate the validity of the method, we consider the static case where the
mass of one of the particles becomes very large. We show that the heavy
particle follows a classical trajectory and we find a good agreement with the
Klein-Gordon result.


title: The standard model at low energies

abstract:
  The hadronic sector of the standard model at low energies is described by a
non--decoupling effective field theory, chiral perturbation theory. An
introduction is given to the construction of effective chiral Lagrangians, both
in the purely mesonic sector and with inclusion of baryons. The connection
between the relativistic formulation and the heavy baryon approach to chiral
perturbation theory with baryons is reviewed.


title:
Effective Lagrangian Approach to Electroweak Baryogenesis: Higgs mass
  limit and Electric dipole moments of fermion

abstract:
  A natural solution to the hierachy problem of the standard model is to assume
new physics to appear at the TeV scale. We parametrize the effects of this new
physics in terms of an effective lagrangian and examine its impacts on
electroweak baryogenesis. We point out that with such an effective lagrangian
successful electroweak baryogenesis implies: i) Higgs boson lies within the
reach of LEP II; ii)electric dipole moments of electron and neutron are
detectable in the near future.


title: Subleading Heavy Quark Effects in a Nonrelativistic Quark Model

abstract:
  I present a very simple model, based on the model of Isgur, Scora, Grinstein
and Wise \cite{ISGW}, which can be used to calculate the effects which appear
at subleading order in heavy quark effective theory. I include both general
formalism and specific results. The formalism transparently reproduces the
results of heavy quark effective theory, while giving insight into such things
as the vanishing of certain form factors at zero recoil. I discuss the
implications of these results for both heavy quark effective theory and the
Isgur-Scora-Grinstein-Wise model.


title: Review of Z' Physics at Future Colliders

abstract:
  We present recent developments in the diagnostic study of heavy gauge bosons
at future colliders with the emphasis on the determination of gauge couplings
of $Z'$ to quarks and leptons. Proposed diagnostic probes at future hadron
colliders are discussed. The study of statistical uncertainties expected for
the above probes at the LHC and $M_{Z'}\simeq 1$ TeV shows that three out of
four normalized couplings can be determined, thus allowing for a distinction
between models. The complementary nature of the probes at future $e^+e^-$
colliders is also discussed.


title: The Decay $B\to\pi\ell\nu$ in Heavy Quark Effective Theory

abstract:
  We present a systematic analysis of the $B^{(*)}\to\pi\,\ell\,\nu$ weak decay
form factors to order $1/m_b$ in the heavy quark effective theory, including a
discussion of renormalization group effects. These processes are described by a
set of ten universal functions (two at leading order, and eight at order
$1/m_b$), which are defined in terms of matrix elements of operators in the
effective theory. In the soft pion limit, the effective theory yields
normalization conditions for these functions, which generalize the well-known
current algebra relations derived from the combination of heavy quark and
chiral symmetries to next-to-leading order in $1/m_b$. In particular, the
effects of the nearby $B^*$-pole are correctly contained in the form factors of
the effective theory. We discuss the prospects for a model independent
determination of $|V_{ub}|$ and the $B B^*\pi$ coupling constant from these
processes.


title: Is Heavy Quark Axion Necessarily Hadronic Axion?

abstract:
  We show that heavy quark axion is not necessarily a hadronic axion, which
manifests in the quark and lepton seesaw mechanism. We introduce a heavy
$SU(2)$ singlet fermion for each known fermion in order to unify the axion
scale and the seesaw scale. The light quarks and leptons gain their masses by
the seesaw mechanism. Even though our axion model gives a kind of heavy quark
axion, the axion has tree level lepton--axion coupling suppressed by $F_a$,
contrary to a widely known belief that heavy quark axions are hadronic.


title: Fermion Doubling and a Natural Solution of the Strong CP Problem

abstract:
  We suggest the fermion doubling for all quarks and leptons. It is a
generalization of the neutrino doubling of the seesaw mechanism. The new quarks
and leptons are $SU(2)$ singlets and carry the electromagnetic charges of their
lighter counterparts. An $SU(3)$ {\it anomaly free global symmetry} or a
discrete symmetry can be introduced to restrict the Yukawa couplings. The form
of mass matrix is belonging to that of Nelson and Barr even though our model
does not belong to Barr's criterion. The weak CP violation of the
Kobayashi-Maskawa form is obtained through the spontaneous breaking of CP
symmetry at high energy scale. The strong CP solution is through a specific
form of the mass matrix. At low energy, the particle content is the same as in
the standard model. For a model with a global symmetry, in addition there
exists a massless majoron.


title: The $\tau$ neutrino as a Majorana particle

abstract:
  A Majorana mass term for the $\tau$ neutrino would induce neutrino -
antineutrino mixing and thereby a process which violates fermion number by two
units. We study the possibility of distinguishing between a massive Majorana
and a Dirac $\tau$ neutrino, by measuring fermion number violating processes in
a deep inelastic scattering experiment $\nu p \rightarrow \tau X$. We show
that, if the neutrino beam is obtained from the decay of high energetic pions,
the probability of obtaining "wrong sign" $\tau$ leptons is suppressed by a
factor ${\cal{O}}(m_{\nu_{\tau}}^2 \theta^2/m_{\mu}^2)$ instead of the naively
expected suppression factor $\theta^2 m_{\nu_{\tau}}^2/E_{\nu}^2$, where
$E_{\nu}$ is the $\tau$ neutrino energy, $m_{\nu_{\tau}}$ and $m_{\mu}$ are the
$\tau$-neutrino and muon masses, respectively, and $\theta$ is the $\nu_{\mu}$
- $\nu_{\tau}$ mixing angle. If $m_{\nu_{\tau}}$ is of the order of 10 MeV and
$\theta$ is of the order of $0.01 - 0.04$ (the present bounds are
($m_{\nu_{\tau}} < 35 MeV, \theta < 0.04$) the next round of experiments may be
able to distinguish between Majorana and Dirac $\tau$-neutrinos.


title:
Pion Form Factors at Intermediate Momentum Transfer in a Covariant
  Approach

abstract:
  We study the pion electromagnetic and $\gamma^* + \pi^0 \to \gamma$
transition form factors at intermediate momentum transfer. We calculate soft,
nonperturbative corrections to the leading perturbative amplitudes which arise
from the $q\bar q$-component of the pion wave function. We work in Minkowski
space and use a Lorentz covariant, gauge-invariant generalized perturbative
integral representation for the $q\bar q$ amplitudes. For the transition form
factor we find relative insensitivity to the detailed nonperturbative structure
of the wavefunction for $|q^2|\gsim 10$~GeV$^2$, whereas considerable
sensitivity is found for the electromagnetic form factor.


title: Supersymmetry and Supergravity: Phenomenology and Grand Unification

abstract:
  A survey is given of supersymmetry and supergravity and their phenomenology.
Some of the topics discussed are the basic ideas of global supersymmetry, the
minimal supersymmetric Standard Model (MSSM) and its phenomenology, the basic
ideas of local supersymmetry (supergravity), grand unification, supersymmetry
breaking in supergravity grand unified models, radiative breaking of $SU(2)
\times U(1)$, proton decay, cosmological constraints, and predictions of
supergravity grand unified models. While the number of detailed derivations are
necessarily limited, a sufficient number of results are given so that a reader
can get a working knowledge of this field.


title: An $O(3)$ Global Anomaly in 0+1 Dimension

abstract:
  We present a simple exactly solvable quantum mechanical example of the global
anomaly in an $O(3)$ model with an odd number of fermionic triplets coupled to
a gauge field on a circle. Because the fundamental group is non-trivial, $\pi_1
(O(3)) ={\bf Z}_2$, fermionic level crossing or circling occur in the
eigenvalue spectrum of the 1-dim. Dirac \op under continuous external field
transformations. They are shown to be related to the presence of an odd number
of normalizable zero modes in the spectrum of an appropriate 2-dim. Dirac \op .
We argue that fermionic degrees of freedom in the presence of an infinitely
large external field violate perturbative decoupling.


title: Light Quark Energy Distribution in Heavy Quark Symmetry

abstract:
  Using heavy quark symmetry we construct an energy sum rule relating the form
factor of a heavy flavored meson $\xi(w)$ to the light quark energy
distribution. We find that the current available data for $\xi(w)$ is
consistent with a broad energy distribution rather than with that of a pure
quark/anti-quark bound state, indicating a large nonvalence content.


title: Scaling Violation in the Fragmentation Functions in e+e- Annihilation

abstract:
  A determination of the hadronic fragmentation functions of the Z-boson is
presented from a study of the inclusive hadron production wit the DELPHI
detector at LEP. These fragmentation functions were compared with the ones at
lower energies, thus covering data in a large kinematic range:
  196 <= Q^2 <= 8312 GeV^2 and x(= p_h/E_beam) > 0.08
  A large scaling violation was observed, which was used to extract the strong
coupling constant in second order QCD:
  alpha_s(Mz) =0.118 +\- 0.005.
  The corresponding QCD scale for five quark flavours is:
  Lambda_MS_bar = 230 +/- 60 MeV.


title: Threshold Effects And Perturbative Unification

abstract:
  We discuss the effect of the renormalization procedure in the computation of
the unification point for running coupling constants. We explore the effects of
threshold--crossing on the $\beta$--functions. We compute the running of the
coupling constants of the Standard Model, between $m_Z$ and $M_P$, using a mass
dependent subtraction procedure, and then compare the results with $\bar{MS}$,
and with the $\theta$-- function approximation. We also do this for the Minimal
Supersymmetric extension of the Standard Model. In the latter, the bounds on
susy masses that one obtains by requiring perturbative unification are
dependent, to some extent, on the procedure.


title: Covariant Variable Front Quark Model

abstract:
  We study the implications of Lorentz symmetry for hadronic structure by
formulating a manifestly covariant constituent quark model and find full
covariance for any Lorentz transformation requires utilizing a variable
quantization surface. Even though time-reversal invariance mandates a unique
orientation for the surface's direction, we investigated alternative choices
and find small numerical sensitivity to different directions. We also calculate
the static properties of the low lying pseudoscalar mesons and compare results
with existing noncovariant calculations. We conclude that there is a little
sensitivity of the calculated observables to the choice of the formalism,
provided relativity is properly implemented.


title:
Determining the Penguin Effect on CP Violation in $B^0 \rightarrow \pi^+
  \pi^-$

abstract:
  A major goal in B physics is measuring the CP-violating asymmetry in the
decay $B^0 \rightarrow \pi^+ \pi^-$. In order to determine one of the phase
angles in the CKM matrix from this decay it is necessary to determine the
influence of the penguin amplitude. Here we show how, using $SU(3)$ symmetry,
the penguin effect can be approximately determined from the ratio of the decay
rates of $B^0 \rightarrow K^+ \pi^-$ and $B^0 \rightarrow \pi^+ \pi^-$.


title: Generalized Relativistic Meson Wave Function

abstract:
  We study the most general, relativistic, constituent $q{\overline q}$ meson
wave function within a new covariant framework. We find that by including a
tensor wave function component, a pure valence quark model is now capable of
reproducing not only all static pion data ($f_\pi$, $\langle r_\pi^2 \rangle$)
but also the distribution amplitude, form factor $(F_\pi(Q^2))$, and structure
functions. Further, our generalized spin wave function provides a much better
detailed description of meson properties than models using a simple
relativistic extension of the $S=L=0$ nonrelativistic wave function.


title:
Evidence for Color Fluctuations in Hadrons from Coherent Nuclear
  Diffraction}

abstract:
  A QCD-based treatment of projectile size fluctuations is used to compute
inelastic diffractive cross sections $\sigma_{diff}$ for coherent
hadron-nuclear processes. We find that fluctuations near the average size give
the major contribution to the cross section with $ \le few \%$ contribution
from small size configurations.
  The computed values of $\sigma_{diff}$ are consistent with the limited
available data. The importance of coherent diffraction studies for a wide range
of projectiles for high energy Fermilab fixed target experiments is emphasized.
The implications of these significant color fluctuations for relativistic heavy
ion collisions are discussed.


title: Can Stop be Light Enough ?

abstract:
  \def\nle{{\stackrel{<}{\sim}}} We examine a possibility for existence of a
light supersymmetric partner of the top quark (stop) with mass 15 $\sim$ 20 GeV
in the framework of the minimal supergravity GUT model. Such light stop could
explain the slight excess of the high $p_{T}$ cross section of the
$D^{*\pm}$-meson production in two-photon process at TRISTAN. We point out that
the existence of such stop could change the dominant decay mode of some
particles and could weaken substantially present experimental bounds on the
supersymmetric parameter space. It seems that there is a finite parameter
region allowing existence of the light stop even if we consider the present
experimental data. Inversely, if the light stop was discovered at TRISTAN,
masses and mixing parameters of the other SUSY partners as well as masses of
the Higgs and the top will be severely constrained, for example, $m_{\tilde{g}}
\simeq$75GeV, $m_{\tilde{W_{1}}}\nle$55GeV, 90GeV$\nle m_{\tilde{\ell}}
\nle$130GeV, 100GeV$\nle m_{\tilde{q}}\nle$150GeV, $m_{h}\nle$60GeV and
115GeV$\nle m_{t}\nle$135GeV. Some phenomenological implications on the present
and future experiments are also discussed.


title:
Muonium Hyperfine Structure and the Decay $ \mu ^+\to e^+ +\overline \nu
  _e +\nu _{\mu}$ in Models with Dilepton Gauge Bosons

abstract:
  We examine the muonium ($\mu ^+e^-$)-antimuonium ($\mu ^-e^+$) system in the
models which accomodate the dilepton gauge bosons, and study their
contributions to the ground state hyperfine splitting in ``muonium''. We also
consider the exotic muon decay $\mu ^+\to e^+ +\overline \nu _e +\nu _{\mu}$
mediated by the dilepton gauge boson, and obtain a lower bound $(M_{X^{\pm
}}/g_{3l})>550 \rm GeV$ at 90\% confidence level for the singly-charged
dilepton mass using the unitarity relation of the Kobayashi-Maskawa matrix for
the 3-family case.


title: New Bounds on Leptoquarks

abstract:
  We show that FCNC processes are unavoidable for leptoquarks that couple to
left handed quarks, and derive new FCNC bounds from neutral meson mixing.
Despite being induced only at one loop, these processes lead to significant
bounds since the leptoquark contributions do not suffer from GIM cancellations.
Studying the implications of these bounds we find that (i) The D-Dbar mixing
bound is the first significant FCNC bound from the up sector. Combining it with
FCNC bounds from the down sector we arrive at a bound on the first generation
couplings. (ii) The K-Kbar and D-Dbar mixings bound g^2/M while all other
processes bound g/M. The combined neutral meson mixing bound is therefore
dominant for the heavier leptoquarks, and leads to exclusion of large regions
in parameter space which were previously allowed.


title: Computing Quark and Gluon Distribution Functions for Very Large Nuclei

abstract:
  We argue that the distribution functions for quarks and gluons are computable
at small x for sufficiently large nuclei, perhaps larger than can be physically
realized. For such nuclei, we argue that weak coupling methods may be used. We
show that the computation of the distribution functions can be recast as a many
body problem with a modified propagator, a coupling constant which depends on
the multiplicity of particles per unit rapidity per unit area, and for
non-abelian gauge theories, some extra media dependent vertices. We explicitly
compute the distribution function for gluons to lowest order, and argue how
they may be computed in higher order.


title: Large--order behavior of non--decoupling effects and triviality

abstract:
  We compute some non--decoupling effects in the standard model, such as the
$\rho$ parameter, to all orders in the coupling constant expansion. We analyze
their large order behavior and explicitly show how it is related to the
non--perturbative cutoff dependence of these non--decoupling effects due to the
triviality of the theory.


title: Theoretical Approaches to $B \to K^* \gamma$

abstract:
  We describe two recent theoretical calculations of the $B \to K^* \gamma$
decay. The first method is based on an effective lagrangian incorporating
chiral symmetry for the light degrees of freedom and the heavy quark
spin-flavor symmetries for the heavy quarks. Using these symmetries, together
with the hypothesis of polar q$^2$ dependence of the semileptonic form factors,
one is able to relate $B \to K^* \gamma$ and $D \to K^* \ell \nu$ decays with
the result $ R \, =\, \Gamma(B \to K^* \gamma) / \Gamma(b \to s \gamma) = 0.09
\pm 0.03$. The second method is based on 3-point function QCD sum rules and
gives the result $ R \, = \, 0.17 \pm 0.05$. Both results are in reasonable
agreement with recent data from the CLEO II Collaboration.


title:
The Central Temperature of the Sun can be Measured via the $^7$Be Solar
  Neutrino Line

abstract:
  A precise test of the theory of stellar evolution can be performed by
measuring the difference in average energy between the neutrino line produced
by ${\rm ^7Be}$ electron capture in the solar interior and the corresponding
neutrino line produced in a terrestrial laboratory. The high temperatures in
the center of the sun broaden the line asymmetrically, FWHM = 1.6~keV, and
cause an average energy shift of 1.3~keV. The width of the $^7$Be neutrino line
should be taken into account in calculations of vacuum neutrino oscillations.


title:
Infrared Fixed Point Solution for the Top Quark Mass and Unification of
  Couplings in the MSSM

abstract:
  We analyze the implications of the infrared quasi fixed point solution for
the top quark mass in the Minimal Supersymmetric Standard Model. This solution
could explain in a natural way the relatively large value of the top quark mass
and, if confirmed experimentally, may be suggestive of the onset of
nonperturbative physics at very high energy scales. In the framework of grand
unification, the expected bottom quark - tau lepton Yukawa coupling unification
is very sensitive to the fixed point structure of the top quark mass. For the
presently allowed values of the electroweak parameters and the bottom quark
mass, the Yukawa coupling unification implies that the top quark mass must be
within ten percent of its fixed point values.


title: Higgs Bosons at the Fermilab Tevatron

abstract:
  The Wjj background has increased by 70%. This decreases the significance of
the WH signal somewhat. The significance of the ZH signal remains about the
same.


title: Violation Of The $\Delta I = 1/2$ Rule In $D \to \pi\pi$ Decays

abstract:
  A strong violation of the $\displaystyle{\Delta I = {1\over 2}} $ rule has
experimentally been found in the $\displaystyle{D \to \pi\pi}$ decays [1]. In
this letter we will show that the order of magnitude of this violation can be
understood in terms of the pure quantum chromo dynamics corrections to the weak
interactions.


title:
The Effect of Supersymmetric Particles on b -> s \gamma Decay in
  Supergravity Models

abstract:
  The effect of loops involving charginos with up-type squarks, and gluinos
with down-type squarks, on the inclusive decay mode $b\rightarrow s\gamma$ is
studied in the context of minimal $N=1$ Supergravity models with a radiatively
broken electroweak symmetry group. It is confirmed that the strong constraints
imposed by the CLEO upper bound $B(b\rightarrow s\gamma)<5.4\times 10^{-4}$ on
two-Higgs doublets models are much weaker in supersymmetric theories due to
partial cancelations from loops involving charginos and up-type squarks. The
dependence of the branching ratio and the supersymmetry masses on the top quark
mass is explored.


title:
Effective Fermion Models in Symmetry-Breaking Phase and Quantum
  Chromodynamics

abstract:
  In our lecture we discuss the fermion models with quasilocal interaction
implemented by derivatives and a momentum cutoff as substitutes of QCD at low
energies. They are investigated in the strong coupling regime when several
coupling constants are matched to their critical values. It is found that
around polycritical points there appear a number of resonances with the same
quantum numbers. Respectively the particular change of enviroment caused by
gluon condensate results in the mass splitting independent of the cutoff. Such
models are supposed to be an essential ingredient in the description of quark
matter at high baryon densities.


title: Electroweak gauge bosons self--energies: complete QCD corrections

abstract:
  We present the (two--loop) QCD corrections to the longitudinal and transverse
components of the electroweak gauge bosons self--energies for arbitrary
momentum transfer and for different internal quark masses. Compact formulae for
both the real and imaginary parts are given in the general case as well as in
some physically interesting special cases. The dependence on the definition of
the quark masses is discussed.


title: R Symmetry Breaking Versus Supersymmetry Breaking

abstract:
  We point out a connection between R symmetry and \susy\ breaking. We show
that the existence of an R symmetry is a necessary condition for \susy\
breaking and a spontaneously broken R symmetry is a sufficient condition
provided two conditions are satisfied. These conditions are: {\it genericity},
\ie\ the effective Lagrangian is a generic Lagrangian consistent with the
symmetries of the theory (no fine tuning), and {\it calculability}, \ie\ the
low energy theory can be described by a supersymmetric Wess-Zumino effective
Lagrangian without gauge fields. All known models of dynamical supersymmetry
breaking possess such a spontaneously broken R symmetry and therefore contain a
potentially troublesome axion. However, we use the fact that genericity is {\it
not} a feature of supersymmetric theories, even when nonperturbative
renormalization is included, to show that the R symmetry can in many cases be
explicitly broken without restoring supersymmetry and so the axion can be given
an acceptably large mass.


title: Effective Lagrangian Approach to the Fermion Mass Problem

abstract:
  An effective theory is proposed, combining the standard gauge group
$SU(3)_{C}\otimes SU(2)_{L}\otimes U(1)_{Y}$ with a horizontal discrete
symmetry. By assigning appropriate charges under this discrete symmetry to the
various fermion fields and to (at least) two Higgs doublets, the broad spread
of the fermion mass and mixing angle spectrum can be explained as a result of
suppressed, non-renormalisable terms. A particular model is constructed which
achieves the above while simultaneously suppressing neutral Higgs-induced
flavour-changing processes.


title:
Resonant and Non-Resonant Pieces of the $D\rightarrow \bar{K}\pi$
  Semileptonic Transition Amplitude

abstract:
  We compare the resonant and non-resonant contributions in various regions of
phase space for the $D\rightarrow \bar{K}\p$ semileptonic transition amplitude,
computed in a chiral model which incorporates the heavy quark symmetry. Remarks
on the significance for experiment and for chiral perturbation theory are made.
hep-ph/yymmnnn


title: Order \alpha^4 R_{\infty} corrections to positronium P levels

abstract:
  The order $\alpha^4 R_{\infty}$ corrections to positronium $P$ levels are
found. The calculation is reduced to the ordinary perturbation theory for the
nonrelativistic Schr\"odinger equation. The perturbation operators have the
Breit-type structure and are obtained by calculating on-mass-shell diagrams.
Found energy corrections constitute numerically $\delta E(2 ^1 P_1)=0.06$ MHz,
$\delta E(2 ^3 P_2)=0.08$ MHz, $\delta E(2 ^3 P_1)=0.025$ MHz, $\delta E(2 ^3
P_2)=-0.58$ MHz.


title: Search for Flavoured Multiquarks in a Simple Bag Model

abstract:
  We use a bag model to study flavoured mesonic $(Qq\bar q\bar q)$ and baryonic
$({\overline Q}qqqq)$ states, where one heavy quark $Q$ is associated with
light quarks or antiquarks, and search for possible stable multiquarks. No
bound state is found. However some states lie not too high above their
dissociation threshold, suggesting the possibility of resonances, or perhaps
bound states in improved models.


title: Calculating the Bound on the Light Higgs Mass in General SUSY Models

abstract:
  In the Minimal Supersymmetric Standard Model (MSSM) the existence of an upper
bound on the mass of the $CP=+1$ lightest Higgs boson, equal to $m_Z$ at
tree--level and $\simlt 120\ GeV$ after the inclusion of radiative corrections,
has important phenomenological consequences for Higgs searches. A similar
bound, independent of mass parameters other than the electroweak scale, can be
calculated in supersymmetric models with an extended Higgs sector. In models
with arbitrary Higgs sectors perturbative up to $10^{16}\ GeV$, we find,
including radiative corrections, $m_h \simlt 155\ GeV$ for $m_t \simlt 190\
GeV$.


title:
Bound State Soliton Description of Low Partial Wave Octet Baryon
  Resonances

abstract:
  A version of the bound state soliton model which allows both $\eta$ and $K$
bound states is used to study low partial wave octet baryon resonances. It is
found that negative parity $S-$wave resonances are well described within this
framework. A possible interpretation of the $P-$wave resonances is also
discussed.


title: More on Symmetries in Heavy Quark Effective Theory

abstract:
  We present a general classification of all normal and ``chiral" symmetries of
heavy quark effective theories. Some peculiarities and conondrums associated
with the ``chiral" symmetries are discussed.


title: Oblique Corrections To The W Width

abstract:
  The lowest-order expression for the partial $W$ width to $e \nu ,~\Gamma (W
\to e \nu) = G_\mu M_W^3 /(6 \pi \sqrt{2})$, has no oblique radiative
corrections from new physics if the measured $W$ mass is used. Here $G_\mu =
(1.16639 \pm 0.00002) \times 10^{-5}$ GeV/$c^2$ is the muon decay constant. For
the present value of $M_W = (80.14 \pm 0.27)$ GeV/$c^2$, and with $m_t = 140$
GeV$/c^2$, one expects $\Gamma (W \to e \nu) = (224.4 \pm 2.3)$ MeV. The total
width $\Gamma_{\rm tot}(W)$ is also expected to lack oblique corrections from
new physics, so that $\Gamma_{\rm tot} (W)/ \Gamma (W \to e \nu) = 3 + 6 [1 +
\{\alpha_s (M_W)/\pi \}]$. Present data are consistent with this prediction.


title: Observable Consequences of a Scalar Boson Coupled only to Neutrinos

abstract:
  We have examined the consequences of assuming the existence of a light scalar
boson, weakly coupled to neutrinos, and not coupled to any other light
fermions. For a range of parameters, we find that this hypothesis leads to the
development of neutrino clusters which form in the early Universe and which
provide gravitational fluctuations on scales small compared to a parsec (i.e.,
the scale of solar systems). The existence of such clustering produces an
effect which would appear as a negative mass squared for the electron neutrino
in Tritium beta decay, without conflicting with other experiments. The neutrino
masses arising in unified gauge theories would then be very much larger than
the masses extracted from experiments within the solar system.


title: B--Physics in Hadron Colliders

abstract:
  The possibility of exploring the systematics of the spectroscopy, strong
dynamics, and the weak and rare decay modes of b--quark systems at hadron
colliders such as Fermilab, LHC and SSC, is discussed. A copious yield of
$10^{10}$ detected $B$--mesons is readily accessible in a dedicated Fermilab
program, and implies a vast array of accessible decay modes, including second
order weak processes and $CP$--violation, which will be unavailable elsewhere
until the commissioning of LHC or SSC. Kinematic and flavor tagging, utilizing
the ``daughter pions'' from resonances, is expected to play a major role in
semileptonic weak decay studies and the search for $CP$--violation. Plenary
talk, Workshop on $B$ Physics at Hadron Accelerators, Snowmass, Colorado, June
25, 1993; Invited Lecture, TASI, Boulder, Colorado, June 18, 1993.


title: Model independent constraints on leptoquarks from rare processes

abstract:
  We present model independent constraints on the masses and couplings to
fermions of $B$ and $L$ conserving leptoquarks. Such vector or scalar particles
could have masses below 100 GeV and be produced at HERA; we list the generation
dependent bounds that can be calculated from rare lepton and meson decays,
meson-anti-meson mixing and various electroweak tests. PLEASE NOTE: this file
does not contain tables and figures, so is not very useful. Complete paper
available (by mail) from sacha@physics.berkeley.edu.


title: QCD improved estimates to rare B-Decays at the heavy b-quark limit

abstract:
  The renormalization effects from the b-quark scale down to the
non-perturbative QCD regime are studied for rare $B$-decays at the heavy
b-quark limit. Phenomenological consequences of these effects are investigated.
We find that the anomalous scaling behavior plays a positive role in making
non-perturbative model calculations consistent with recent CLEO measurements of
$B\rightarrow K^* \gamma .$


title: Discrete Gauge Symmetries in Supersymmetric Grand Unified Models

abstract:
  We investigate the presence of discrete gauge symmetries in Grand Unification
models based in $SO(10)$ and $E_6$. These models include {\it flipped} and {\it
unflipped} $SU(5)$, $SU(4)\!\times\! SU(2)_L\!\times\! SU(2)_R$,
$SU(3)_C\!\times\! SU(3)_L\!\times\! SU(3)_R$, and $SU(6)\!\times\! SU(2)$.
Using the Dynkin formalism we find the $U(1)$ subalgebras contained in the
unified groups, give an expression for the Higgs fields that preserve each
discrete symmetry, and determine the low-energy matter content implied by
chirality. We discuss two $Z_2$ and three $Z_3$ nonequivalent cases. Among the
possibilities found, only the usual $Z_2$ matter parity (R-parity) of
supersymmetric extensions is consistent with a minimal matter content with no
right- handed neutrinos, extra Higgs doublets, or nonstandard {\it down}-type
quarks.


title:
New Supersymmetric Electroweak Gauge Model with Natural Baryon-Number
  Conservation

abstract:
  Baryon number (B) is automatically conserved in the standard SU(2) X U(1)
electroweak gauge model, but not in its supersymmetric extension where it must
be imposed as an extra condition. This undesirable feature is avoided in the
conventional left-right supersymmetric extension, but then flavor-changing
neutral currents (FCNC) are not naturally suppressed. A new version is proposed
with automatic B conservation as well as FCNC suppression (except for u quarks
through scalar exchange).


title: Pion Compton Scattering in Perturbative QCD

abstract:
  Pion Compton scattering is studied in perturbative QCD for real and
space--like initial photons. Different methods for the convolution of the hard
amplitude with the pion wave--functions, which have in the past led to
conflicting results, are compared.


title: Summary of the Extensions of the Standard Model Working Group

abstract:
  We summarize the results of the extended gauge group working group of the
Madison-Argonne Workshop on Present and Future Colliders. Contributions are
described on the previously unexamined two photon fusion production of heavy
leptons, new studies of $Z'$ couplings to $\nu \bar{\nu}$ and $q\bar{q}$, and
previously unexplored vector leptoquark production. More detailed accounts of
these studies can be found in individual contributions.


title: Stability of Neutrinos in the Singlet Majoron Model

abstract:
  We show that there is no one-loop enhancement of the rate for a light
neutrino to decay into a lighter neutrino plus a majoron, contrary to a recent
claim. Thus the light neutrinos must satisfy the cosmological bound of having
masses less than 35 eV in the singlet majoron model, or else violate the
constraint imposed by galaxy formation. In the latter case, $\nu_\tau$ could
have a mass between 40 and 500 keV, while satisfying all other cosmological
constraints.


title: Physics of Polarized pp Collisions

abstract:
  I will summarize the physics that can be investigated with polarized pp
collisions. It is technically feasible to use the RHIC collider for
accelerating highly polarized protons to a center-of-mass energy of about 400
GeV, with high luminosity. Such collisions can be used to probe the
spin-dependence of hard collisions and of partons in a hadron, including the
gluons. There are interesting twist 3 phenomena that are likely to be
significant in view of the large transverse spin asymmetries at lower energies;
this will have important implications for the spin structure of the proton wave
function. Recent theoretical developments include the possibility of probing
the spin of transversely polarized quarks via asymmetries in the jets they
make.


title: Electroweak Physics at Current Accelerators and the Supercollider

abstract:
  The activities of the Electroweak Physics Working Group are summarized. Three
main issues are addressed: 1) prospects for measuring the $W$ mass at the
Tevatron using the inclusive electron energy spectrum, 2) constraining the
strange quark distribution function in $W$ + charm production, and 3)
possibilities to determine the three vector boson couplings at the Tevatron and
SSC.


title: Topics in String Phenomenology

abstract:
  We consider two questions in string ``phenomenology.''
  First, are there any generic string predictions? Second, are there any
general lessons which string theory suggests for thinking about low energy
models, particularly in the framework of supersymmetry? Among the topics we
consider are the squark and slepton spectrum, flavor symmetries, discrete
symmetries including $CP$, and Peccei-Quinn symmetries. We also note that in
some cases, discrete symmetries can be used to constrain the form of
supersymmetry breaking.


title: Inhomogeneous Field Configurations and the Electroweak Phase Transition

abstract:
  We investigate the effects of inhomogeneous scalar field configurations on
the electroweak phase transition. For this purpose we calculate the leading
perturbative correction to the wave function correction term $Z(\vph,T)$, i.e.,
the kinetic term in the effective action, for the electroweak Standard Model at
finite temperature and the top quark self--mass. Our finding for the fermionic
contribution to $Z(\vph,T)$ is infra--red finite and disagrees with other
recent results. In general, neither the order of the phase transition nor the
temperature at which it occurs change, once $Z(\vph,T)$ is included. But a
non--vanishing, positive (negative) $Z(\vph,T)$ enhances (decreases) the
critical droplet surface tension and the strength of the phase transition. We
find that in the range of parameter space, which allows for a first--order
phase transition, the wave function correction term is negative --- indicating
a weaker phase transition --- and especially for small field values so large
that perturbation theory becomes unreliable.


title: Chiral Lagrangian with higher resonances and flavour $ SU(3) $ breaking

abstract:
  A chiral Lagrangian with $ SU(3) $ breaking and higher resonances is
proposed. In this model, the $ SU(3) $ breaking structure in
vector-pseudoscalar sector is realized with the decay constants of pseudoscalar
mesons and the masses of vector mesons used as inputs. We examine whether the
resulting $ SU(3) $ breaking effect in the charge radii of pseudoscalar mesons
is consistent with the experimental facts.


title:
Probing Three-Boson Anomalous Couplings in $e^+e^-\to W^+W^-$ at Future
  Linear $e^+e^-$ Colliders with Polarized Beams

abstract:
  We study the potential of the next-generation $e^+ e^-$ linear colliders with
longitudinally polarized beams, to restrict the values of the anomalous
trilinear couplings $WW\gamma$ and $WWZ$ from the measurement of the process
$e^+ e^-\to W^+ W^-$. Along with initial $e^+e^-$ polarization, we account also
for the possibilities offered by cross sections for polarized final $W$, in
order to disentangle the constraints on the various constants. The results show
the essential role of the initial beams polarization in improving the bounds
obtained from the unpolarized case.


title:
On the Distribution of Neutral and Charged Pions through the Production
  of a Classical Pion Field

abstract:
  High energy reactions may produce a state around the collision point that is
best described by a classical pion field. Such a field might be an isospin
rotated vacuum of the chiral $\sigma$-model or, as discussed in this work, a
solution of the equations of motion resultinng from the coupling of fields of
this model to quarks produced in the collision. In such configurations all
directions in isospin space are allowed leading to a sizable probability of
events with, essentially, only charged particles (Centauros) or all neutral
particles (anti-Centauros). (In more common statistical models of multiparticle
production, the probability of such events is suppressed exponentially by the
total multiplicity.) We find that the isospin violation due to the mass
difference of the up and down quarks has a significant effect on these
distributions and enhances the production of events consisting predominantly of
neutral particles.


title:
Vector boson Pair Production at Supercolliders; useful approximate
  helicity amplitudes

abstract:
  We study vector boson pair production at $LHC$ and $SSC$, taking into account
the effects generated by the anomalous vector boson and Higgs couplings induced
by the operators ${\cal O}_W$ and ${\cal O}_{UW}$, which are the only dim=6
operators preserving $SU(2)_c$. These operators lead to enhanced production of
transverse vector bosons, as opposed to the enhanced production of longitudinal
gauge bosons, induced in case $M_H\gsim 1\ TeV$, by dim=4 terms already
existing in the Standard Model lagrangian. For vector boson pair masses larger
than $1\ TeV$, we establish very simple approximate expressions for the
standard as well as the non-standard helicity amplitudes for $q\bar q$
annihilation and vector boson fusion, which accurately describe the physics.
These expressions should simplify the experimental search for such
interactions. We finally discuss the observability and the disentangling of
these interactions.


title: New Physics Effects on CP Violation in $B$ Decays

abstract:
  We review new physics effects on CP violation in B decays. We describe the
Standard Model predictions for the various types of CP asymmetries and discuss
the theoretical cleanliness of these predictions. We point out the ingredients
in the analysis that are most sensitive to new physics and deduce the type of
new physics that is likely to modify the Standard Model predictions. Several
explicit examples are discussed in detail. Finally, we explain how, if
deviations from the Standard Model predictions are measured, we will be able to
learn detailed features of the new physics involved. Plenary talk presented at
the Workshop on B Physics at Hadron Accelerators, Snowmass, Colorado, June 21 -
July 2, 1993.


title:
Relation between $\sin^2\hat{\theta}_W(m_Z)$ and
  $\sin^2\theta_{eff}^{lep}$

abstract:
  The relation between $\sef$, frequently employed in LEP analyses, and the
$\rm{\overline{MS}}$--parameter $\scr$ is discussed and their difference
evaluated by means of an explicit calculation.


title: Energy Levels Of Hydrogen-Like Atomsand Fundamental Constants

abstract:
  The present review includes the description of theoretical methods for the
investigations of the spectra of hydrogen-like systems. Various versions of the
quasipotential approach and the method of the effective Dirac equation are
considered. The new methods, which have been developed in the eighties, are
described. These are the method for the investigation of the spectra by means
of the quasipotential equation with the relativistic reduced mass and the
method for a selection of the logarithmic corrections by means of the
renormalization group equation. The special attention is given to the
construction of a perturbation theory and the selection of graphs, whereof the
contributions of different orders of $\alpha$, the fine structure constant, to
the energy of the fine and hyperfine splitting in a positronium, a muonium and
a hydrogen atom could be calculated.
  In the second part of this article the comparison of the experimental results
and the theoretical results concerning the wide range of topics is produced.
They are the fine and hyperfine splitting in the hydrogenic systems, the Lamb
shift and the anomalous magnetic moments of an electron and a muon. Also, the
problem of the precision determination of a numerical value of the fine
structure constant, connected with the above topics, is discussed.


title:
On the $A$ dependence of $R = \sigma_L/\sigma_T$ and the $Q^2$
  dependence of Shadowing

abstract:
  A higher--twist nuclear enhancement of $R = \sigma_L/\sigma_T$, as might be
expected to arise due to fermi motion and whose magnitude is within the
error-bars of recent experiment, is shown to lead to a monotonic {\it decrease}
in the ratio of nuclear vs. nucleon cross--sections at small Bjorken $x$ for
{\it increasing} $Q^2$. This effect at small $x$, comparable in magnitude to
those reported for shadowing, is driven mainly by kinematic factors and
essentially vanishes for $x > .1$. Its unusual $Q^2$ dependence rather
complicates the unravelling from present data in the shadowing region the
corresponding dependence in $Q^2$ of the nuclear structure functions,
$F_2^{A}(x,Q^2)$.


title:
On the $p^4$--corrections to $K \to 3\pi$ decay amplitudes in nonlinear
  and linear chiral models

abstract:
  The calculations of isotopic amplitudes and their results for the direct
$CP$--violating charge asymmetry in $K^\pm \to 3\pi$ decays within the
nonlinear and linear ($\sigma$--model) chiral Lagrangian approach are compared
with each other. It is shown, that the latter, taking into account intermediate
scalar resonances, does not reproduce the $p^4$--corrections of the nonlinear
approach introduced by Gasser and Leutwyler, being saturated mainly by vector
resonance exchange. The resulting differences concerning the $CP$ violation
effect are traced in some detail.


title: Phenomenological Quark Mass Matrix Model with Two Adjustable Parameters

abstract:
  A phenomenological quark mass matrix model which includes only two adjustable
parameters is proposed from the point of view of the unification of quark and
lepton mass matrices. The model can provide reasonable values of quark mass
ratios and Kobayashi-Maskawa matrix parameters.


title:
Trying to Catch the Elusive $a^0$ and More. Reactions Initiated by
  $b$--Quarks the Higgs Sector of ${\cal MSSM}$

abstract:
  We study the cross sections for the production of a neutral, intermediate
mass Higgs boson in the processes $pp\rightarrow tq'\Phi$, $pp\rightarrow
tW^-\Phi$ and $pp\rightarrow bZ^0\Phi$ in the Minimal Supersymmetric Standard
Model ($\Phi=H^0,h^0$ and $A^0$) at Supercollider energies. The additional
heavy particles ($t$, $W$, $Z$) in the final state can be used for tagging
purposes, increasing the signal to background ratio. These reactions are
dominated by $bq$ and $bg$ fusion. Their relevance for Higgs particle searches
is discussed taking into account the expected efficiencies and purities for
$b$--tagging. We find that, for tan$\beta = 30$, the cross sections for
$pp\rightarrow bZ^0\Phi$ are larger than 14 $pb$, over the whole intemediate
range of $M_{A^0}$, for $A^0$ and at least one of the other two Higgses.
Therefore this reaction is an excellent candidate for the discovery of one or
more $\cal MSSM$ Higgs particles.}


title:
Examples of Semiclassical Instanton-Like Scattering: Massless $\phi^4$
  and SU(2) Gauge Theories

abstract:
  Two-parameter sets of solutions to the classical field equations in the
massless $\phi^4$ model and SU(2) gauge theory are found, each solution
presumably describing a multi-particle instanton-like transition at high
energy. In the limit of small number of initial particles, the probability of
the transition is suppressed by $\exp(-2S_0)$, where $S_0$ is the instanton
action.


title: Gluon multiplication in high energy heavy ion collisions

abstract:
  Hot gluons are the dominant components of the QCD plasma to be formed in
future high energy heavy ion experiments. In this paper we study the elementary
processes in the plasma medium for gluon multiplication based on all orders of
the tree-diagrams in perturbative QCD. When applying to the chemical
equilibration in the expanding system, we found that the gluons reaches
chemical equilibrium well within its plasma phase. The inclusion of all the
next-to-leading order processes makes the equilibration considerably faster
than the simple $gg\leftrightarrow ggg$ one considered previously.


title: The Bess Model at e+ e- Colliders

abstract:
  We consider the possibility of detecting vector resonances from a strong
electroweak sector, in the framework of the BESS model, at future $e^+ e^-$
colliders up to the TeV range. If the mass $M_V$ of the new vector boson
multiplet is not far above or if it is below the maximum machine energy, such a
contribution would be manifest. The process of $W$-pair production by $e^+e^-$
annihilation allows for sensitive tests of the strong sector, especially if the
$W$ polarizations are reconstructed. Contribution to the proceedings of the
Workshop on Physics and Experiment at Linear $e^+ e^-$ Colliders - Munich,
Annecy, Hamburg 1993.


title: Naturalness Versus Supersymmetric Non-renormalization Theorems

abstract:
  We give an intuitive proof of a new non-renormalization theorem in
supersymmetric field theories. It applies both perturbatively and
non-perturbatively. The superpotential is not renormalized in perturbation
theory but receives non-perturbative corrections. However, these
non-perturbative corrections are {\it not} generic functions of the fields
consistent with the symmetries. Certain invariant terms are not generated. This
violation of naturalness has applications to dynamical supersymmetry breaking.


title:
Effects of the large gluon polarization on $xg_1^d(x)$ and J/$\psi$
  productions at polarized ep and pp collisions

abstract:
  The recent SMC data of $xg_1^d(x)$ are reproduced with the large polarized
gluons. To study further the polarized gluon distribution in a proton, we
calculate the spin--dependent differential cross section for J/$\psi$
leptoproductions and the two--spin asymmetry for J/$\psi$ hadroproductions. Its
experimental implication is discussed.


title: Electroweak Symmetry Breaking at the Supercollider

abstract:
  Invited talk presented at the Workshop on Physics at Current Accelerators and
the Supercollider, Argonne, Illinois, and at the 17th Johns Hopkins Workshop on
Current Problems in Particle Theory, Budapest, Hungary.


title:
Gauge-independent extraction of the next-to-leading-order Debye mass
  from the gluon propagator

abstract:
  It is shown that by defining the Debye mass through the relevant pole of the
static gluon propagator rather than the zero-momentum limit of the time-time
component of the gluon self-energy, a gauge-independent result for the
next-to-leading order correction can be derived upon resummation of
hard-thermal-loop contributions. The result turns out to be logarithmically
sensitive to the magnetic screening mass. [Talk given at the 3rd Workshop on
Thermal Field Theories and their Applications, August 15-27, 1993, Banff,
Alberta, Canada]


title: Measuring $\Lambda_{\overline{MS}}$ at LEP

abstract:
  We show that standard next-to-leading order (NLO) perturbative QCD analyses
used to extract $\alpha_{s}$ from LEP data do not serve to disentangle the
completely unknown renormalization scheme (RS) invariant next-NLO (NNLO) and
higher-order uncalculated corrections from those dependent on the
renormalization scale in a predictable manner. The resulting quoted values of
$\alpha_{s}(M_{Z})$ $(\tilde{\Lambda}_{\overline{MS}})$ with attendant scheme
dependence uncertainties therefore reflect the ad hoc way in which they were
extracted, rather than the actual values of these parameters. Choosing the
scale so that the NLO coefficient vanishes (effective charge scheme) exposes
the relative size of these unknown RS invariant higher order terms. They are
seen to be sizeable for some of the LEP observables, indicating that they must
be estimated if $\tilde{\Lambda}_{\overline{MS}}$ is to be determined reliably.
This can be accomplished either from NNLO calculations, at present only
available for the hadronic width of the $Z^{0}$ ($R_{Z}$), or
non-perturbatively by writing the RS-invariant uncertainty in $\tilde{\Lambda}$
in terms of the running ${dR(Q)}/{d \ln Q}$ of the observable R(Q) with energy
using an effective charge formalism. The NNLO calculations for $R_{Z}$ and LEP
data supplemented by lower energy PETRA data lead to
$\tilde{\Lambda}^{(5)}_{\overline{MS}}=287 \pm 100$ MeV. We also


title:
Gamma^*, Z^* production in polarised p-p scattering as a probe of the
  proton spin structure

abstract:
  We present the results of a detailed study of the large transverse momentum
Drell-Yan process, pp --> (Gamma^*, Z^*)X --> l^+l^- X at collider energies,
with either one or both protons polarised, allowing the study of single- and
double-spin asymmetries respectively. We show how these asymmetries obtained
from angular distributions of the leptons in the Gamma^* (or Z^*) rest-frame,
can be used to get information on the polarised parton distributions. Numerical
results for the asymmetries and the cross-sections are presented, and the
sensitivity of the asymmetries to the initial parton distributions indicates
that these can be used as effective probes of the spin structure of the proton.


title:
New perturbative upper bound on M_H from fermionic Higgs decays at two
  loops

abstract:
  We present the dominant two-loop ${\rm O}\left(G_F^2M_H^4\right)$ electroweak
corrections to the fermi\-onic decay widths of a high-mass Higgs boson in the
Standard Model. The corrections are negative and quite significant, and are
larger in magnitude than the one-loop electroweak corrections for $M_H\gsim
400\ {\rm GeV}$. This indicates the onset of a breakdown of perturbation theory
in the Higgs sector of the Standard Model at this surprisingly low value of the
Higgs-boson mass.


title:
Production of CP-Odd Higgs Bosons with Large Transverse Momentum at
  Hadron Supercolliders

abstract:
  A two Higgs doublet model is employed to study the production of a CP-odd
Higgs boson ($A$) associated with a large transverse momentum jet ($j$) at
hadron supercolliders. The cross section of $pp \to jA+X$ is evaluated with
four subprocesses: $gg \to gA$, $gq \to qA$, $g\bar{q} \to \bar{q}A$ and
$q\bar{q} \to gA$. We find that $pp \to jA+X$ is a significant source of CP-odd
Higgs bosons at future hadron supercolliders.


title: Solar Neutrino Decay

abstract:
  We re-examine the neutrino decay solution to the solar neutrino problem in
light of the new data from Gallex II and Kamiokande III. We compare the
experimental data with the solar models of Bahcall and Pinsonneault and
Turck-Chieze and find that neutrino decay is ruled out as a solution to the
solar neutrino problem at better than the 98\% c.l. even when solar model
uncertainties are taken into account.


title: Order m alpha^8 Contributions to the Decay Rate of Orthopositronium

abstract:
  We discuss how contributions to the order ${\cal O} (m \alpha^8)$
orthopositronium decay rate can be separated into two categories, one due to
relativistic momenta and calculable in terms of QED scattering amplitudes, the
other due to low momenta and calculable in the simpler framework of a
low-energy effective theory (NRQED). We report new results for all low-momentum
contributions, and give a formula relating the remaining contributions to
conventional (on-shell) QED scattering amplitudes.


title: A new signal for scalar top bound state production

abstract:
  We study the production and decay of a scalar \stst\ bound state \sigst\ at
hadron supercolliders, where \st\ is the lighter stop eigenstate. If \st\ has
no tree--level 2--body decays, the dominant decay modes of \sigst\ are $gg$ or,
if $m_h < \mst \ll \mstt$, a pair of light scalar Higgs bosons $h$.
Nevertheless the branching ratio into two photons is often large enough to
yield a detectable signal.


title:
Gauge Invariant Three-Boson Vertices in the Standard Model and the
  Static Properties of the W

abstract:
  We use the S-matrix pinch technique to derive to one loop-order gauge
independent $\gamma W^{+} W^{-} $ and Z $W^{+} W^{-}$ vertices in the context
of the Standard Model,with all three incoming momenta off-shell. We show that
the $\gamma W^{+} W^{-}$ vertex so constructed is related to the
gauge-independent W self-energy,derived by Degrassi and Sirlin,by a very simple
QED-like Ward identity.The same results are obtained by the pinch technique
applied directly to the process $e^{+}e^{-} \rightarrow W^{+}W^{-}$. Explicit
calculations give rise to expressions for the static properties of the
  W gauge bosons like magnetic dipole and electric quadruple moments which
being gauge independent satisfy such crucial properties as infrared finiteness
and perturbative unitarity.


title:
Squark Mass Determination at the Next Generation of Linear $e^+e^-$
  Colliders

abstract:
  Current mass limits allow the possibility that squarks may be produced in
large numbers at the next generation of linear $e^+e^-$ colliders. In this
paper we investigate the prospects for precision studies of squark masses at
such colliders. We assume that squarks are lighter than gluinos, and discuss
both direct and cascade decay scenarios. By exploiting the clean environment
and polarizable beams of linear $e^+e^-$ colliders, we find that squark mass
determinations at the level of a few GeV are possible in a large part of the
parameter space.


title: The Decay $b \to s \gamma$ In The Mssm Revisited

abstract:
  We present a re-analysis of the decay $\bsgamma$ in the Minimal
Supersymmetric Standard Model with radiatively induced breaking of $SU(2)
\times U(1)$. We extend this analysis to regions of the supersymmetric
parameter space wider than those previously studied. Results are explicitly
presented for $m_t=150\GeV$. We emphasize the consequences for future searches
of charged Higgs and charginos from a measurement of the branching ratio for
this decay compatible with the Standard Model prediction. In spite of the
strong sensitivity of this decay to the effects of supersymmetry, we find that,
at the moment, no lower limit on the mass of these particles can be obtained.
The large chargino contributions to the branching ratio for $\bsgamma$, for
large values of $\tan \beta$, are effectively reduced by pushing the lightest
eigenvalue of the up-squark mass matrix closer to the electroweak scale, i.e.
by increasing the degree of degeneracy among the up-squarks.


title: Electroweak Processes and Precision Tests

abstract:
  Review of the electroweak sector of the minimal standard model, Basic LEP
processes at the tree level, 1-loop radiative corrections in the on-shell
renormalization scheme, Star scheme and oblique corrections, Introduction to
oblique parameters.


title: QCD Effects in Particle Production on Nuclei

abstract:
  I discuss some questions related to hard scattering processes in nuclei and
corrections to the leading twist approximation. The QCD factorization theorem
requires that high energy partons do not lose energy while traversing the
nucleus. I explain the physical reason for this. The theorem also states that
spectator partons, not involved in the hard collision, have no influence on the
inclusive cross section. Important spectator effects are, however, seen in the
data for certain reactions and in some kinematical regions. I discuss the
reasons from a phenomenological and theoretical point of view. Finally, I
mention some methods for analyzing hard processes in regions of very large $x$,
where the leading twist terms are not dominant.


title: Influence of Light and Heavy Thresholds on SUSY Unification

abstract:
  In this paper we study and compare susy unification using two different
approaches in order to take into account the effect of light particle
thresholds on the evolution of gauge couplings: the step--function
approximation, on the one hand, and a mass dependent procedure, which gives a
more accurate description of the dependence of the results on the masses, on
the other. We also include the effect of heavy thresholds, when $SU(5)$ is
chosen as the unifying group. We find that the mass--dependent procedure
excludes scenarios where all susy masses are below $1\;TeV$, and favors a value
of $\alpha_3(m_Z)$ near its upper experimental bound, contrary to the results
obtained with the step--function approximation. We underline the dependence of
the results on the procedure chosen to deal with light thresholds.


title: Comparison of 1/mQ^2 Corrections in Mesons and Baryons

abstract:
  We extend our relativistic quark model to the study of the decay Lambda_b ->
Lambda_c ell nu and verify that the model satisfies the heavy-quark symmetry
constraints at order 1/mQ^2. We isolate a strong dependence on a parameter
which measures the relative distortion in the light-quark wave functions of the
Lambda_b and Lambda_c. This parameter and the 1/mQ^2 corrections turn out to be
small. The dependence on a corresponding parameter in the meson case leads to
large 1/mQ^2 corrections.