title: Quantum tunnelings with global charge

abstract:
  We investigate quantum tunneling in the theory of a complex scalar field with
a global $U(1)$ symmetry when the charge density of the initial configuration
does not vanish. We discuss the possible final configurations and set up the
Euclidean path integral formalism to find the bubble nucleation and to study
the bubble evolution. For the stationary path, or the bounce solution, in the
Euclidean time, the phase variable becomes pure imaginary so that the charge
density remains real. We apply this formalism to examples when the initial
charge density is small. While the phase transition considered here occurs in
zero temperature, the bubble dynamics is richly complicated, involving
conserved charge, the sound wave and the supersonic bubble wall.


title: Confinement and the Pion Nucleon Sigma Term

abstract:
  Gribov's theory of confinement offers a simple explanaton of the value of the
pion nucleon sigma term. There is no need to invoke a large strange quark
component in the nucleon.


title: Leptonic Signals from off-shell Z Boson Pairs at Hadron Colliders

abstract:
  We study the gluon fusion into pairs of off-shell Z bosons and their
subsequent decay into charged lepton pairs at hadron colliders. We do not
restrict the intermediate state Z bosons to the narrow width approximation but
allow for arbitrary invariant masses. We compare the strength of this process
with the known leading order results for q q_bar -> Z Z -> 4 l and for g g -> H
-> Z Z -> 4 l .


title: Heavy Quark Masses, Mixing Angles, and Spin-Flavour Symmetry

abstract:
  In a series of three lectures, I review the theory and phenomenology of heavy
quark masses and mixing angles and the status of their determination. In
addition, I give an introduction to heavy quark symmetry, with the main
emphasis on the development of heavy quark effective field theory and its
application to obtain a model-independent determination of $|V_{cb}|$.


title: Implications of Supersymmetric Grand Unification

abstract:
  Unification of the interactions of the Standard Model is possible in its
simplest supersymmetric extension. The implications of the $\lambda _t$
fixed-point solution on the top mass and on Higgs phenomenology is discussed.
Expected correlations between the masses of various supersymmetric particles
are detailed.


title: A Three Configurations Diquark Model for Baryons

abstract:
  The wave functions in the diquark-quark model for baryons are modified to
take into account the effect of the different masses of the quarks in diquark
formation. A spatial wave function is introduced multiplying each flavour-spin
configuration in the quark-diquark model. Futhermore a numerical coefficient is
introduced which weighes the contribution of each configuration.


title: New Supernova Constraints on active-sterile neutrino conversions

abstract:
  We consider active-sterile neutrino conversions in a supernova in the
presence of random magnetic field domains. For large enough fields the
magnetization of the medium may enhance the active to sterile neutrino
conversion rates. Neglecting neutrino transition magnetic moments we show that
for KeV neutrino mass squared differences these limits may overcome those that
would apply in the isotropic case.


title: Recent Results in Neutrino Physics

abstract:
  Invited Talk at {\sl ICNAPP}, Bangalore, India, Jan. 1994; {\sl Int. School
on Cosmological Dark Matter}, Valencia, Oct. 1993; and Gran Sasso meeting on
{\sl Solar Neutrino Problem: astrophysics or oscillations?}, march 1994.


title:
Off-shell pion electromagnetic form factor from a gauge-invariant
  Nambu-Jona-Lasinio model

abstract:
  The off--shell electromagnetic vertex function of pions and kaons is studied
in a bosonized Nambu--Jona-Lasinio model with a gauge--invariant proper--time
cutoff. The slope of the pion form factor with respect to the pion 4--momentum
is found to be equal to the on--shell pion charge radius in the chiral limit.
The off--shell slope of the $K^0$ form factor is zero, that of the $K^\pm$
about 15\% smaller than that of the pion. We compare our results with those of
a recent calculation in chiral perturbation theory.


title: Electroweak Baryogenesis and Standard Model CP Violation

abstract:
  We analyze the mechanism of electroweak baryogenesis proposed by Farrar and
Shaposhnikov in which the phase of the CKM mixing matrix is the only source of
$CP$ violation. This mechanism is based on a phase separation of baryons via
the scattering of quasiparticles by the wall of an expanding bubble produced at
the electroweak phase transition. In agreement with the recent work of Gavela,
Hern\'andez, Orloff and P\`ene, we conclude that QCD damping effects reduce the
asymmetry produced to a negligible amount. We interpret the damping as quantum
decoherence. We compute the asymmetry analytically. Our analysis reflects the
observation that only a thin, outer layer of the bubble contributes to the
coherent scattering of the quasiparticles. The generality of our arguments
rules out any mechanism of electroweak baryogenesis that does not make use of a
new source of $CP$ violation.


title: Chiral phase transition in an expanding quark antiquark plasma

abstract:
  We investigate the time evolution of a quark antiquark plasma by solving
numerically the relativistic transport equations derived on the Hartree level
from the Nambu-Jona-Lasinio model. We find that the phase transition in the
expanding quark antiquark plasma is different as compared to that in a static
plasma. The expansion competes with the transition and finally quark droplets
will be formed which subsequently hadronizes. These findings raise the question
whether static thermal models can make at all any prediction about signals of
that transition .


title: Search for the Invisibly Decaying Higgs Particle at LEP and the LHC

abstract:
  The Higgs particle can have dominantly invisible decay in a large class of
Majoron models as well as some SUSY models. The LEP signal and mass limit for a
Higgs particle undergoing invisible decay are explored. They are found to be
very similar to those for the standard model decay. The best signatures and
discovery limit for an invisibly decaying Higgs particle at the LHC are also
discussed.
  (Invited Talk at the XXIXth Rencontres de Moriond on QCD and High Energy
Hadronic Interactions, M\'eribel, France, 19--26 March 1994.)


title:
Renormalization of Heavy Quark Effective Field Theory: Quantum Action
  Principles and Equations of Motion

abstract:
  We discuss the quantum action principles and equations of motion for Heavy
Quark Effective Field Theory. We prove the so-called equivalence theorem for
HQEFT which states that the physical predictions of HQEFT are independent from
the choice of interpolating fields. En passant we point out that HQEFT is in
fact more subtle than the quantum mechanical Foldy-Wouthuysen transformation.


title: On the Significance of the Electroweak Precision Data

abstract:
  We elaborate on a recently suggested effective Lagrangian for charged-current
and neutral-current electroweak interactions which in comparison with the
standard electroweak theory contains three free parameters $\Delta x, \Delta
y$, $\varepsilon$ which quantify different sources for violations of $SU(2)$
symmetry. Within the standard $SU(2)_I \times U(1)_Y$ electroweak theory, we
present both exact and very much refined approximate analytical one-loop
expressions for these parameters in terms of the canonical input, $G_\mu, \MZ$,
$\alpz$, the top-quark mass, $\Mt$, and the Higgs-boson mass, $\MH$. We
reemphase the importance of discriminating between the {\it empirically
well-known purely fermionic} (vacuum polarization) contributions to $\Delta x,
\Delta y$, $\varepsilon$ and the {\it empirically unknown bosonic} ones with
respect to present and future electroweak precision tests. The parameters
$\Delta x$ and $\varepsilon$ are hardly affected by standard bosonic
corrections, while the full one-loop results for $\Delta y$ differ appreciably
from the ones obtained by taking into account fermion loops only. A detailed
comparison with the experimental data on $\MWpm/\MZ$, $\bar\sw^2$, $\Gamma_l$
shows that these data start to become accurate enough to be sensitive to
standard (bosonic) contributions to $\Delta y$ beyond fermion loops.


title:
A Transient New Coherent Condition of Matter: The Signal for New Physics
  in Hadronic Diffractive Scattering

abstract:
  We demonstrate the existence of an anomalous structure in the data on the
diffractive elastic scattering of hadrons at high energies and small momentum
transfer. We analyze five sets of experimental data on $p(\overline{p})-p $
scattering from five different experiments with colliding beams, ranging from
the first-- and second--generation experiments at $\sqrt{s} = 53 $ GeV to the
most recent experiments at 546 GeV and at 1800 GeV. All of the data sets
exhibit a localized anomalous structure in momentum transfer. We represent the
anomalous behavior by a phenomenological formula. This is based upon the idea
that a transient coherent condition of matter occurs in some of the
intermediate inelastic states which give rise, via unitarity, to diffractive
elastic scattering. The Fourier--Bessel transform into momentum--transfer space
of a spatial oscillatory behavior of matter in the impact--parameter plane
results in a small piece of the diffractive amplitude which exhibits a
localized anomalous behavior near a definite value of $-t $. In addition, we
emphasize possible signals coming directly from such a new condition of matter
that may be present in current experiments on inelastic processes.


title: Semi-Empirical Bound on the Chlorinr-37 Solar Neutrino Experiment

abstract:
  The Kamiokande measurement of energetic Boron-8 neutrinos from the sun is
used to set a lower bound on the contribution of the same neutrinos to the
signal in the \Chlorine\ experiment. Implications for Beryllium-7 neutrinos are
discussed.


title:
Chiral Meson Lagrangians from the QCD Based NJL Model Modified by
  Nonlocal Effects

abstract:
  Starting from a QCD inspired bilocal quark interaction we obtain a local
effective meson lagrangian. In contrast to previous local (NJL-like)
approaches, we include nonlocal corrections related to the finite meson size
which we characterize by a small parameter. After bosonization using the
heat-kernel method we predict the structure coefficients of the
Gasser-Leutwyler $p^4$-lagrangian up to first order in this parameter. The
modifications for the $L_i$ coefficients are typically of the order 10-20\%,
except for $L_5$, where we find a stronger nonlocal influence.


title:
A Measurement of the Branching Fraction ${\cal B} \tau^+ \to h^- \pi^0
  \nu_\tau$

abstract:
  Using data from the CLEO II detector at CESR, we measure ${\cal
B}(\tau^\pm\rightarrow h^\pm\pi^0\nu_\tau)$ where $h^\pm$ refers to either
$\pi^\pm$ or $K^\pm$. We use three different methods to measure this branching
fraction. The combined result is ${\cal B}(\tau^\pm\rightarrow
h^\pm\pi^0\nu_\tau) = 0.2587 \pm 0.0012 \pm 0.0042$, in good agreement with
Standard Model predictions. This result, in combination with other precision
measurements, reduces the significance of the one-prong problem in tau decays.
A postscript version is available through World-Wide-Web in
http://w4.lns.cornell.edu/public/CLNS/1994/


title: Cosmological Constant and Soft Terms in Supergravity

abstract:
  Some of the soft SUSY breaking parameters in hidden sector supergravity model
depend on the expectation value of the hidden sector scalar potential, $<V_h>$,
whose tree level value is equal to the tree level cosmological constant. The
current practice of calculating soft parameters assumes that $<V_h>=0$. Quantum
correction to the cosmological constant can differ from the correction to
$<V_h>$ by an amount of order $m^2_{3/2}M_{Pl}^2/8\pi$. This implies that, for
the vanishing cosmological constant, the $<V_h>$--dependent parts of soft terms
can be sizable, and hence the supergravity phenomenology should be accordingly
modified.


title:
Exact Multiparticle Amplitudes at Threshold in Large-N Component phi^4
  Theory

abstract:
  I derive the set of recurrence relations between the amplitudes of
multiparticle production at threshold in the standard large-N limit of the
O(N)-symmetric phi^4$ theory which sums all relevant diagrams with arbitrary
number of loops. I find an exact solution to the recurrence relations using the
Gelfand--Dikii representation of the diagonal resolvent of the Schrodinger
operator. The result coincides with the tree amplitudes while the effect of
loops is the renormalization of the coupling constant and mass. The form of the
solution is due to the fact that the exact amplitude of the process 2->n at n>2
vanishes on mass shell when averaged over the O(N)-indices of incoming
particles for dynamical reasons because of the cancellation between diagrams. I
discuss some possible applications of large-N amplitudes, in particular, for
the renormalon problem.


title: All electroweak four fermion processes in electron-positron collisions

abstract:
  This paper studies the electroweak production of all possible four fermion
states in e+ e- collisions. Since the methods employed to evaluate the complete
matrix elements and phase space are very general, all four fermion final states
in which the charged particles are detected can be considered. Also all kinds
of experimental cuts can be imposed. With the help of the constructed event
generator a large number of illustrative results is obtained, which show the
relevance of backgrounds to a number of signals. For LEP 200 the W-pair signal
and its background are discussed, for higher energies also Z-pair and single W
and Z signals and backgrounds are presented.


title: A Review of Hadronic and Rare B Decays

abstract:
  We review recent experimental results on B meson decays. These include
measurements of the inclusive production of charmed and non-charmed mesons and
baryons, the reconstruction of a large number of exclusive hadronic final
states with charmed mesons, the search for exclusive hadronic final states
without charmed mesons, and the first observation of the decay B-> K* gamma
which is described by an electromagnetic penguin diagram. The theoretical
implications of these results will be considered. The figures can be obtained
in postscript format EMAIL from kh@ohstpy.mps.ohio-state.edu.


title: A New Bottom-Up Approach for the Construction of Fermion Mass Matrices

abstract:
  We describe a new technique which enables one to construct an
SO(10)-symmetric fermion mass matrix model at the supersymmetric grand
unification scale directly from the fermion mass and mixing data at the low
energy scale. Applications to two different neutrino mass and mixing scenarios
are given.


title: The Solar Neutrino Problem: Neither Astrophysics Nor Oscillations?

abstract:
  There is no consistent solar model which can describe all experimental data
on the solar neutrinos. The problem can be formulated essentially in a model
independent way. The key points are the comparison of the Homestake and the
Kamiokande data as well as the comparison of the GALLEX and SAGE results with
minimal signal estimated from the solar luminosity. It is argued than in such a
comparison one should use the Homestake-II data (only after 1986) with caution.
The results of the model independent analysis show strong suppression of the
beryllium neutrino flux. The data can be well described by the resonant flavor
conversion. For the ``low flux model" which can accommodate the Kamiokande
signal, a consistent solution can be found for the neutrino mass squared
difference $\Delta m^2 = (0.3 - 1.0)\cdot 10^{-5}$ eV$^2$ and values of mixing
angle $\sin^2 2\theta > 5 \cdot 10^{-4}$ (``very small mixing solution").


title: Chiral Invariance of Massive Fermions

abstract:
  We show that a massive fermion theory, while not invariant under the
conventional chiral transformation, is invariant under a $m$-deformed chiral
transformation. These transformations and the associated conserved charges are
nonlocal but reduce to the usual transformations and charges when $m=0$. The
$m$-deformed charges commute with helicity and satisfy the conventional chiral
algebra.


title:
Is \lq\lq Heavy Quark Damping Rate Puzzle'' in Hot QCD Really the
  Puzzle?

abstract:
  Within the framework of perturbative resummation scheme of Pisarski and
Braaten, the decay- or damping-rate of a moving heavy quark (muon) to leading
order in weak coupling in hot QCD (QED) is examined. Although, as is well
known, the conventionally-defined damping rate diverges logarithmically at the
infrared limit, shown is that no such divergence appears in the physically
measurable decay rate. The cancellation occurs between the contribution from
the \lq\lq real'' decay diagram and the contribution from the diagrams with
\lq\lq thermal radiative correction''.


title:
Low Energy Nucleon-Nucleon Scattering with the Skyrme Model in the
  Geodetic Approximation

abstract:
  We calculate nucleon-nucleon scattering at low energies and large impact
parameter in the Skyrme model within the framework for soliton scattering
proposed by Manton. This corresponds to a truncation of the degrees of freedom
to the twelve collective coordinates which essentially describe the rigid body
motion of the pair of Skyrmions. We take to its logical conclusion the result
that the induced kinetic energy for these collective coordinates in the product
ansatz behaves as one over the separation and hence can dominate over the
potential. This behaviour implies to leading order that we can drop the
potential and the resulting motion reduces simply to geodesic motion on the
manifold parametrized by the variables of the product ansatz. We formulate the
semi-classical quantization of these variables to obtain the motion
corresponding to the nucleonic states of the Skyrme model. This is the
appropriate description for the nucleons in order to consider their scattering
within Manton's framework in the semi-classical approximation. We investigate
the implications for the scattering of nucleons with various initial
polarizations using the approximation method of ``variation of constants''.


title: Low Energy Skyrmion-Skyrmion Scattering

abstract:
  We study the scattering of Skyrmions at low energy and large separation using
the method proposed by Manton of truncation to a finite number of degrees
freedom. We calculate the induced metric on the manifold of the union of
gradient flow curves, which for large separation, to first non-trivial order is
parametrized by the variables of the product ansatz. (presented at the Lake
Louise Winter Institute, 1994)


title: Leptoquark Pair Production at $ep$ Colliders

abstract:
  The pair production cross section for scalar and vector leptoquarks at $ep$
colliders is calculated for the case of photon--gluon fusion. In a model
independent analysis we consider the most general $C$ and $P$ conserving
couplings of gluons and photons to both scalar and vector leptoquarks described
by an effective low--energy Lagangian which obeys $U(1)_{em} \times SU(3)_c$
invariance. Numerical predictions are given for the kinematical regime at HERA
and LEP~$\otimes$~LHC.


title: Higher Twist Effects in the Drell-Yan Angular Distribution

abstract:
  We study the Drell-Yan process $\pi N \rightarrow \mu^+ \mu^- X$ at large
$x_F$ using perturbative QCD. A higher-twist mechanism suggested by Berger and
Brodsky is known to qualitatively explain the observed $x_F$ dependence of the
muon angular distribution, but the predicted large $x_F$ behavior differs
quantitatively from observations. We have repeated the model calculation taking
into account the effects of nonasymptotic kinematics. At fixed-target energies
we find important corrections which improve the agreement with data. The
asymptotic result of Berger and Brodsky is recovered only at much higher
energies. We discuss the generic reasons for the large corrections at high
$x_F$. A proper understanding of the $x_F \to 1$ data would give important
information on the pion distribution amplitude and exclusive form factor.


title: The Physics of Z' bosons

abstract:
  In these lectures we review the simplest gauge extensions of the standard
model, and the present and future limits on new weak interactions.


title: The Proximal Chiral Phase Transition

abstract:
  We consider the form of the chiral symmetry breaking piece of the effective
potential in the linear sigma model. Surprisingly, it allows for a second local
minimum at both zero and finite temperature. Even though chiral symmetry is not
exact, and therefore is not restored in a true phase transition at finite
temperature, this second minimum can nevertheless mimic many of the effects of
a first order phase transition. We derive a lower limit on the height of the
second minimum relative to the global minimum based on cosmological
considerations; this limit is so weak as to be practically nonexistent. In high
energy nuclear collisions, it may lead to observable effects in Bose-Einstein
interferometry due to domain walls and to coherent pion emission.


title:
Where the excess photons and dileptons in SPS nuclear collisions come
  from?

abstract:
  Recently the first single photon spectra from CERN energy heavy-ion
collisions were reported by WA80, while NA34/3 and NA38 have obtained the
spectra for dileptons with the mass up to 4-5 GeV. The production rates for
photons and dileptons significantly increase when reactions involving the $A_1$
meson are included. However, with the conventional expansion scenario, the
absolute yields are still significantly smaller than the observed ones. It may
indicate that expansion in the ``mixed state" takes much more time.


title: QCD Instantons in Vacuum and Matter

abstract:
  The singlet coupling to the topological charge density in the instanton
vacuum, causes the instantons and antiinstantons to be screened over distances
of the order of 1/2 fm. Dilute instanton systems behave as a free gas, while
dense instanton systems behave as a plasma. The free gas behaviour is favored
by a density of 1 fm$^{-4}$. Owing to the Higgs mechanism, the $\eta$' mass is
heavy (1100 MeV). The vacuum topological susceptibility is small (0.07
fm$^{-4}$) and consistent with the QCD Ward identity. In the chiral limit, the
singlet screening vanishes, leading to a four dimensional plasma state with a
temperature given by the nonet decay constant $f$ (90 MeV). The phase is Debye
screened. In the presence of matter, the screening is quenched, and a
Kosterlitz-Thouless transition may occur signaling the restoration of the
$U_A(1)$ symmetry. We suggest to use the spatial asymptotics of the static
topological charge correlator together with the topological susceptibility to
probe the interplay between the $U_A(1)$ restoration and the chiral restoration
in finite temperature QCD. The relevance of these results to the bulk
thermodynamics in the instanton vacuum is discussed.


title:
First Evidence for Electroweak Radiative Corrections from the New
  Precision Data

abstract:
  The analysis of the newest data on the leptonic $Z$-decays and $m_W$ appears
to reveal the first manifestations of electroweak radiative corrections.
  In fact, these data differ, at the level of $2\sigma$, from their electroweak
Born values, while they agree, to within $1\sigma$, with the theoretical values
which take the electroweak radiative corrections into account. Previous data
were within $1\sigma$ in agreement with both sets of values.


title:
Sphalerons and Large Order Behavior of Perturbation Theory in Lower
  Dimension

abstract:
  Sphalerons -- unstable static solutions of classical field equations in
(d+1)-dimensional space-time -- may be viewed as euclidean solutions in d
dimensions. We discuss their role in the large order asymptotics of the
perturbation theory. Specifically, we calculate their contribution to the large
order behaviour of the ground state energy in a quantum mechanical model. When
the number of negative modes is odd, single sphaleron contribution dominates,
while this contribution vanishes when the number of negative modes is even.
These results are confirmed by numerical calculations.


title: Solar Neutrinos: Hint for Neutrino Mass

abstract:
  The present status of the solar neutrino problem is reviewed. The strongest
motivation for new neutrino physics comes from the complete phenomenological
failure of astrophysical solutions: (1) The standard solar model is excluded by
each of the solar neutrino experiments. (2) The combined results of Homestake
and Kamiokande are incompatible with any astrophysical solution. (3) Even if
the Homestake results were ignored entirely, there is no realistic solar model
so far that describes the Kamiokande and gallium data simultaneously within
their experimental uncertainties. On the other hand, the MSW solutions provide
a complete description of the data, strongly hinting at the existence of mass
and mixing of neutrinos. The MSW predictions for the future experiments are
given in detail. It is stressed that solar model uncertainties are significant
in determining the oscillation parameters and in making predictions for the
future experiments. Especially, a $^8$B flux (or $S_{17}$) smaller by 20\% than
that of the Bahcall-Pinsonneault model can make the interpretation of the
charged to neutral current ratio measurement in SNO ambiguous.


title:
CP Violation in {\boldmath $H \ra t \overline{t}$} Decays at {\boldmath
  $\epem$} Colliders

abstract:
  A helicity asymmetry for top quarks originating from Higgs boson decays is
investigated within the 2-Higgs Doublet Model. The asymmetry is sensitive to CP
violation in the scalar sector of the model, whereas it vanishes in the
Standard Model. It has been checked that without any fine tuning of parameters
the asymmetry can reach $50\%$. Standard decay patterns $\twbdec$ and
$\tbwbdec$ are utilized as spin analyzers to measure the asymmetry. The Higgs
production mechanism considered here is $\hprod$. It has been shown that signal
from the asymmetry can easy overcome the noise for Higgs bosons produced in
future linear $\epem$ colliders at energy $\sqrt{s}=500\gev$ operating with
integrated luminosity $L=2.0\times10^4\lumun$.


title: Renormalization of 4-Quark Operators and QCD-Sum Rules

abstract:
  We compute the renormalization mismatch displayed in 1--loop approximation by
classically equivalent 4-quark operators and coming from different possible
definitions of the $\gamma_5$ matrix in dimensional regularization. The result
is then employed to study the effect of the various treatments of $\gamma_5$
upon the size of radiative corrections to 4-quark condensates in the QCD sum
rules for $\rho$ and $A_1$ mesons. We find that a fully anticommuting
$\gamma_5$ which automatically respects non-anomalous chiral Ward-Slavnov
identities leads to considerably smaller corrections and reduces theoretical
uncertainty in the QCD prediction for the $\tau$ hadronic decay rate.


title: Orsay lectures on confinement (II)

abstract:
  The behaviour of the light quark vacuum in the presence of a heavy quark is
investigated.


title: Evidence for Bosonic Electroweak Corrections in the Standard Model

abstract:
  We present strong indirect evidence for the contribution of bosonic
electroweak corrections in the Standard Model. Although important conceptually,
these corrections give subleading contributions in current high energy
experiments, and it was previously thought that they are difficult to detect.
We also discuss the separate contribution of the Higgs boson.


title:
Gauge Hierarchy, Planck Scale Corrections And The Origin of GUT Scale In
  Supersymmetric $(SU(3))^3$

abstract:
  Within a supersymmetric unified framework we explore the resolution of the
gauge hierarchy problem taking account of the non-renormalizable terms in the
superpotential. For $[SU(3)]^3$ supplemented by a discrete R parity, we find
the remarkable property that the vacuum configuration corresponding to the
correct gauge symmetry breaking remains flat (in the supersymmetric limit) to
all orders in $M^{-1}_{Planck}$. The grand unification scale arises from an
interplay of the Planck and supersymmetry breaking scales. An `internal'
$Z_3\otimes Z_4$ symmetry protects a pair of electroweak doublets from becoming
superheavy, yielding at the same time the supersymmetric `$\mu$ term' with the
right order of magnitude. The $Z_4$ symmetry also acts as matter parity and
eliminates the dangerous baryon number violating couplings.


title: Production of Weak Bosons and Higgs Bosons at e-e- Colliders

abstract:
  We present calculations of cross sections for single $W^-$ and $Z$ production
and $W^-W^-, W^-Z, W^-\gamma, ZZ$, and $W^+W^-$ pair production within the
Standard Model at $e^-e^-$ linear colliders. We evaluate Standard-Model Higgs
boson production in the channels $e^-e^- \to e^-e^- H$, $e^-\nu W^- H$, and
$e^-e^- ZH$. We also illustrate the enhancements in the $W^-W^-$ cross section
that would result from a strongly-interacting Higgs sector or from a $H^{--}$
resonance in a Higgs doublet + triplet model.


title: More on direct CP violation in b -> d + J/psi decays

abstract:
  Direct CP violation can occur in B-meson decays of the type b -> d+c+cbar,
where the charm-anticharm pair forms a J/psi. The CP asymmetry requires the
contribution to the amplitude from decays into other states, which rescatter
into d+J/psi via final state interactions. In particular, states with the same
quark content as d+J/psi can contribute. A perturbative calculation, based on a
quark level description of the rescattering process, gives an asymmetry of
about 1%, due to this effect. This makes it the dominant contribution to the
asymmetry, as suggested by an earlier estimate, based on an hadronic picture.


title: Vector Mesons in Nuclear Medium -- an Effective Lagrangian Approach --

abstract:
  Effective masses of $\rho$ and $\omega$ mesons in nuclear medium are studied
in a hadronic effective theory. Both the pole position and the screening mass
decrease in nuclear matter due to the polarization of the nucleon Dirac sea.
The physical origin of the decrease is a reduction of the wave function
renormalization constant induced by the tensor (vector) interaction of the
$\rho$ ($\omega$) with the nucleon. Relation to the results of the QCD sum
rules is also discussed.


title:
$e^+e^-\to b\bar bW^+W^-$ at the Next Linear Collider, Top-Pairs and
  Higgs Production

abstract:
  The complete matrix element for $e^+e^-\ar W^+W^-\bar b b$ is computed at
tree level and applied to: {\bf a)} $\bar t t$ production and decay ; {\bf b)}
$ZH$ production followed by $Z\ar \bar bb$ and $H\ar WW$. In both cases we
include finite width effects and all irreducible backgrounds.


title:
Constraints on Neutrino-Neutrino Interactions from Primordial
  Nucleosynthesis

abstract:
  We use the constraints arising from primordial nucleosynthesis to bound the
strength $F$ of non-standard neutrino-neutrino interactions, when the
right-handed neutrinos participate in the interaction. We find $F < 3 \times
10^{-3}\ G_F$, which is five orders of magnitude more stringent than the limit
obtained using LEP data. We also show that secret interactions of neutrinos
mediated by massless particles must have a coupling $f$ less than $2 \times
10^{-5}$. This also ameliorates previous limits in the literature.


title:
New Upper Limit for the Branching Ratio of the Omega- to Xi- gamma
  Radiative Decay

abstract:
  We have searched for the rare hyperon radiative decay Omega- to Xi- gamma,
using the Fermilab Proton Center 375 GeV/c charged hyperon beam. Our
measurement of the Omega- beam fraction at 13.6 m from production is (4.8 +_
0.4)10**(-5). No signal was found and we determine a new upper limit of (4.6 x
10**-4) at 90% CL for the Omega- to Xi- gamma branching ratio.


title:
Neutrino Magnetic Moment and the Process $\nu e \rightarrow \nu e
  \gamma$

abstract:
  The contribution of a neutrino magnetic moment $\mu_{\nu}$ to the cross
section of the process $\nu e^{-}\rightarrow \nu e^{-} \gamma $ has been
calculated and compared with the Standard Electroweak one. The radiative
process allows to reach low enough values of $Q^2$ without the need to operate
at very small energies of recoil electrons. Regions in the phase space which
are more favourable to set bounds on $\mu_{\nu}$ are suggested.


title: The Search for Top Squarks at the Fermilab Tevatron Collider

abstract:
  The lighter superpartner of the top quark ($\tt_1$) may be considerably
lighter than squarks of the first two generations, and hence may be accessible
to Tevatron collider searches, even if the other squarks and the gluino are too
heavy. For the range of $m_{\tt_1}$ of interest at the Tevatron, the $\tt_1$
decays to a chargino via $\tt_1 \to b\tw_1$ if this is kinematically allowed;
otherwise, the flavor-changing loop decay $\tt_1 \to c\tz_1$ dominates. In the
latter case, $\tt_1$ production is signalled by jet(s) plus $\eslt$ events. If,
instead, the chargino decay is allowed, $1\ell + b$-$jets + \eslt$ and
$\ell^+\ell'^- + jet(s) + \eslt$ events from leptonic decays of $\tw_1$ provide
the most promising signals. We perform detailed simulations for each of these
signals using ISAJET 7.07 and devise cuts to enable the extraction of each of
these signals above standard model backgrounds from vector boson or top quark
production. With an integrated luminosity of 100 $pb^{-1}$, experiments should
be able to probe top squark masses up to $\sim 100$ GeV in each of these
channels; the detection of the signal in the single lepton channel, however,
requires reasonable capability to tag displaced $b$ decay vertices in the
central region.


title:
Determining the CP-eigenvalues of the Neutral Higgs Bosons of the
  Minimal Supersymmetric Model in $\gam\gam$ Collisions

abstract:
  We determine the optimal laser and $\ep/\em$ energies and polarizations for
{\it directly} determining the CP eigenvalue of each of the neutral Higgs
bosons of the Minimal Supersymmetric Model via measurement of transverse
polarization cross section asymmetry in back-scattered laser photon collisions.
Approximate statistical significances are computed for the measurement of the
CP eigenvalue as a function of Higgs mass and other parameters of the model.


title: Higgs Production in $SU(2)_c$ Symmetric Interactions

abstract:
  We study the sensitivity of Higgs production and decay processes to the
$SU(2)_c$ symmetric couplings $O_W$ and $O_{UW}$. Remarkable results are
obtained in the case of $\gamma \gamma \to H$ and for certain ratios of Higgs
decay widths. We also discuss and complete previous results on unitarity
constraints for such couplings.


title: Representations of General Dimension for the Skyrme Model

abstract:
  We construct the representations of general dimension for the soliton
solution to the $SU(2)$ Skyrme model, and show that at the classical level the
dependence on the dimension of the representation ($2j+1$) appears only as an
overall factor $j(j+1)(2j+1)$ in the Lagrangian density, which may be absorbed
by a rescaling of the parameters. Alternate stabilizing terms in the model will
in general have a different $j$-dependence and have to be rescaled accordingly
in order to achieve representation independent predictions. In contrast the
quantum corrections do depend on the dimension of the representation and in
general differ from those obtained in the fundamental representation of
$SU(2)$.


title: $B_c$--meson production in hadron--hadron collisons

abstract:
  The $B_c$--meson production cross section was calculated in the perturbative
QCD. Various distributions of the charged leptons from the $B_c \to l \nu
J/\psi(\to l^+ l^-)$ decay were obtained. The $B_c$--meson mass measurement
from such decays is also discussed.


title: Precise Vacuum Stability Bound in the Standard Model (addendum)

abstract:
  This is an addendum to the paper of the above title published in Physics
Letters B317, 159 (1993). In that paper, I found the lower bound to the Higgs
mass as a function of the top quark mass one obtains by requiring that the
standard model vacuum be stable. It included all higher order corrections to
two-loops, precise definitions of the Higgs and top masses, etc. Unfortunately,
the results were given for top quark masses between 120 and 160 GeV. In this
addendum, I give the results for masses between 160 and 190 GeV. The main
result, using a value of 0.117 for the strong coupling at the Z-mass, is
M_Higgs > 132 + 2.2 (M_top-170) in GeV units. This increases (decreases) by 4.5
GeV if the strong coupling decreases (increases) by 0.007, and is accurate to 1
GeV in the top mass. This will be submitted to Phys. Lett. as an addendum.


title: Minijet Production at Small x

abstract:
  Soft pomeron exchange at high energy includes minijet production at central
rapidity values. This predicts copious production of minijets in deep inelastic
scattering at small $x$, which is closely related to the fact that $\nu W_2$
exhibits Regge behaviour. It helps to explain also how the integrated inclusive
cross-section for minijet production in $\gamma p$ or $pp$ collisions can be
much greater than the total cross-section.


title: Flavor mixing in the gluino coupling and the nucleon decay

abstract:
  Flavor mixing in the quark-squark-gluino coupling is studied for the minimal
SU(5) SUGRA-GUT model and applied to evaluation of the nucleon lifetime. All
off-diagonal (generation mixing) elements of Yukawa coupling matrices and of
squark/slepton mass matrices are included in solving numerically one-loop
renormalization group equations for MSSM parameters, and the parameter region
consistent with the radiative electroweak symmetry breaking condition is
searched. It is shown that the flavor mixing in the gluino coupling for a large
$\tan\beta$ is of the same order of magnitude as the corresponding
Kobayashi-Maskawa matrix element in both up-type and down-type sector. There
exist parameter regions where the nucleon decay amplitudes for charged lepton
modes are dominated by the gluino dressing process, while for all the examined
regions the neutrino mode amplitudes are dominated by the wino dressing over
the gluino dressing.


title: A New Treatment of Neutrino Oscillations in Medium

abstract:
  A new more rigorous and accurate method for treating neutrino oscillations in
the context of the MSW effect in a medium is proposed. This leads to a new type
of resonance condition which for small mixing angles puts rather stringent
conditions on $E_{\nu}/\delta {m^2}$. The implications on the solar neutrino
problem are discussed.


title: High Energy Hadron-Hadron Scattering

abstract:
  The elastic hadron-hadron scattering at high energies is one of the most
fundamental subjects of all particle physics problems and yet is least
understood in spite of many advances in quantum chromodynamics (QCD) at the
conceptual level. We review here the recent theoretical and experimental status
of the subject as well as the rigorous results of the high energy hadron-hadron
scattering. Surprisingly enough, the high-energy models for the elastic and
diffractive scattering abstracted from the Regge-Pomeron field theory is still
{\it phenomenologically} successful to explain the high-energy scattering data
though no rigorous derivation out of the QCD is yet available.


title: Big Bang Baryogenesis

abstract:
  An overview of baryogenesis in the early Universe is presented. The standard
big bang model including big bang nucleosynthesis and inflation is breifly
reviewed. Three basic models for baryogenesis will be developed: The
``standard" out-of-equilibrium decay model; the decay of scalar consensates
along flat directions in supersymmetric models; and lepto-baryogenesis, which
is the conversion of a lepton asymmetry into a baryon asymmetry via
non-perturbative electroweak interactions.


title: Chiral Symmetry Aspects of the Scalars

abstract:
  Electromagnetic decays of the scalar mesons are shown to be constrained by
chiral symmetry as a consequence of the fact that, in the chiral limit, the two
and three-point functions $<SS-PP>$ and $<VVS>$ satisfy super-convergent
dispersion relations. The QCD asymptotic behavior of the latter is canonical
and it can be saturated by a finite number of resonances. The corresponding
chiral lagrangian for vector and scalar resonances is constructed. Matching to
the correct asymptotic structure generates non-minimal terms which have so far
been ignored. It is found that the width $a_0(980)\to2\gamma$ can be naturally
reproduced suggesting that the $a_0(980)$ is not an exotic particle.


title: Degenerate Neutrinos in Left Right Symmetric Theory

abstract:
  Various hints on the neutrino masses namely, ({\em i}) the solar neutrino
deficit ({\em ii}) the atmospheric neutrino deficit ({\em iii}) the need for
the dark matter and/or ({\em iv}) the non-zero neutrinoless double beta decay
collectively imply that all the three neutrinos must be nearlty degenerate.
This feature can be understood in the left right symmetric theory. We present a
model based on the group $SU(2)_{L}\times SU(2)_R\times U(1)_{B-L}\times
SU(2)_H$ which can explain the required departures from degeneracy in neutrino
masses and large mixing among them without assuming any of the mixing in the
quark or charged lepton sector to be large as would be expected in a typical
$SO(10)$ model.


title: Light Gluinos and the Parton Structure of the Nucleon

abstract:
  We study the effects of light gluinos with mass below about 1 GeV on the
nucleon parton densities and the running of alpha_(S). It is shown that from
the available high-statistics DIS data no lower bound on the gluino mass can be
derived. Also in the new kinematical region accessible at HERA the influence of
such light gluinos on structure f unctions is found to be very small and
difficult to detect. For use in more direct searches involving final state
signatures we present a radiative estimate of the gluino distribution in the
nucleon.


title: Baryon - Antibaryon Production by Disordered Chiral Condensates

abstract:
  We investigate the production of baryons and antibaryons in the central
rapidity region of high energy nuclear collisions within the framework of the
Skyrme model taking into account the effects of explicit chiral symmetry
breaking. We argue that the formation of disordered chiral condensates may lead
to enhanced baryon-antibaryon production at low transverse momentum.


title: Nonequilibrium Quantum Dynamics Of Disoriented Chiral Condensates

abstract:
  The nonequilibrium dynamics of the chiral phase transition expected during
the expansion of the quark-qluon plasma produced in a high energy hadron or
heavy ion collision is studied in the O(4) linear sigma model to leading order
in a large $N$ expansion. Starting from an approximate equilibrium
configuration at an initial proper time $\tau$ in the disordered phase we study
the transition to the ordered broken symmetry phase as the system expands and
cools. We give results for the proper time evolution of the effective pion
mass, the order parameter $<\sigma>$ as well as for the pion two point
correlation function expressed in terms of a time dependent phase space number
density and pair correlation density. We determine the phase space of initial
conditions that lead to instabilities (exponentially growing long wave length
modes) as the system evolves in time. These instabilities are what eventually
lead to disoriented chiral condensates. In our simulations,we found that
instabilities that are formed during the initial phases of the expansion exist
for proper times that are at most $3 fm/c$ and lead to condensate regions that
do not contain large numbers of particles. The damping of instabilities is a
consequence of strong coupling.


title: Perturbation Theory and Relative Space

abstract:
  The validity of non-perturbative methods is questioned. The concept of
relative space is introduced.


title: Higgs Decay to Top Quarks at Hadron Colliders

abstract:
  Higgs bosons which decay principally to top quarks, such as in the minimal
supersymmetric model, produce a peak-dip structure in the $gg\to t\bar t$
invariant-mass spectrum. This structure is potentially observable at the CERN
Large Hadron Collider. (see BNL theory home page
http://penguin.phy.bnl.gov/bnl.html for recent preprints)


title:
Supergravity Solutions in the Low-$\tan\beta$ $ \lambda_t$ Fixed Point
  Region

abstract:
  There has been much discussion in the literature about applying the radiative
electroweak symmetry breaking (EWSB) requirement to GUT models with
supergravity. We motivate and discuss the application of the EWSB requirement
to the low $\tan\beta$ fixed-point region and describe the solutions we find.


title: Dynamical Breakdown of Chirality and Parity in (2+1)-dimensional QED

abstract:
  In the (2+1)-dimensional QED with and without the Chern-Simons term, we find
the non-local gauge in which there is no wavefunction renormalization for the
fermion in the framework of the Schwinger-Dyson equation. By solving the
Schwinger-Dyson equation in the non-local gauge, we find a finite critical
value $N_f^c$ for the number of flavors $N_f$ of four-component Dirac fermions,
above which the chiral symmetry restores irrespective of presence or absence of
the Chern-Simons term. In the same framework, we study the possibility of
dynamical breakdown of the parity. It is shown that the parity is not
dynamically broken. We discuss this reason from the viewpoint of the
Schwinger-Dyson equation.


title: Model-Independent $Z'$ Limits from Electron-Electron Collisions

abstract:
  Model independent constraints on the mass of an extra neutral gauge boson and
its couplings to charged leptons are given for the $e^-e^-$ option of a future
linear collider. Analytic exclusion limits are derived in the Born
approximation. The results are compared with those of the $e^+e^-$ mode. The
influence of radiative corrections is discussed.


title: Monopoles and Quark Confinement: Introduction and Overview

abstract:
  We (try to) pedagogically explain how monopoles arise in QCD, why maximal
Abelian(MA) gauge is ``special'' for monopole study, the Abelian projection in
MA gauge, its resultant degrees of freedom(photons, monopoles and charged
matter fields), and the QCD-equivalent action in terms of these degrees of
freedom. Then we turn to more recent developments in the subject: Abelian
dominance, large $N$ behavior of Abelian projected QCD, mass of the charged
matter fields, notion of an effective photon-monopole action obtained by
integrating out the charged matter fields, and problems encountered in the
recent evaluation of this effective action using the microcanonical demon
method on the lattice.


title:
About the relevance of the Imaginary components of the effective
  couplings in the Asymmetry measurements

abstract:
  The effect coming from imaginary parts of effective couplings in the $e^+
e^-$ asymmetries is investigated. It is shown that for the present level of
experimental accuracy, in some asymmetries the imaginary parts of the effective
couplings cannot be neglected and moreover that the use of different
prescriptions on how to handle them in quoting just real effective couplings
from the data may produce sizable differences. A definition of the real
effective couplings specifying how to handle the imaginary parts is advocated.


title:
Calculation of $<p|\overline{u}u-\overline{d}d|p>$ from QCD sum rule and
  the neutron-proton mass difference

abstract:
  The proton matrix element of the isovector-scalar density,
$<p|\overline{u}u-\overline{d}d|p>/2M_p$, is calculated by evaluating the
nucleon current correlation function in an external isovector-scalar field
using the QCD sum-rule method. In addition to the usual chiral and gluon
condensates of the QCD vacuum, the response of the chiral condensates to the
external isovector field enters the calculation. The latter is determined by
two independent methods. One relates it to the difference between the up and
down quark chiral condensates and the other uses the chiral perturbation
theory. To first order in the quark mass difference $\delta m=m_d-m_u$, the
non-electromagnetic part of the neutron-proton mass difference is given by the
product $\delta m <p|\overline{u}u-\overline{d}d|p>/2M_p$; the resulting value
is in reasonable agreement with the experimental value.


title: CP violation in photon-photon collisions

abstract:
  The effective lagrangian parametrization is used to determine the CP
violating effects in $ \gamma \gamma $ collisions. for the processes studied
the effects are found to be very small, the one exception being scalar
production.


title: Normalization of QCD corrections in top quark decay

abstract:
  We discuss the effects of QCD corrections to the on-shell decay $t \to b W$.
We resolve the scale ambiguity using the Brodsky-Lepage-Mackenzie scheme, and
find that the appropriate coupling constant is $\alpha_{s}^{ \overline{MS}}
(0.122m_{t})$. The largest long distance contribution comes from the definition
of the on-shell mass of the top quark. We note that QCD corrections to the
electroweak $\rho$ parameter are extremely small when the $\rho$ parameter is
expressed in terms of the top quark width.


title:
The Chiral Lagrangian Approach to the Non-universal Effects in the Zbb
  Vertex

abstract:
  We calculate the top quark loop corrections to the Zbb vertex in the chiral
lagrangian of the dynamical electroweak symmetry breaking theory. We use the
effective lagrangian based on coset space SU(2) X U(1) / U(1) with the gauge
interactions switched off, so these corrections are directly related to the
Physics associated with the heavy top quark and the mass generation in the
dynamical models.


title: Effective Lagrangians (for electroweak physics)

abstract:
  In this set of lectures I will present an elementary introduction to the uses
of effective lagrangians in the electroweak interaction with emphasis in
practical applications


title: $|V_{cb}|$ from OPE Sum Rules for Heavy Flavor Transitions

abstract:
  We derive a model-independent upper bound for the axial-vector form factor of
the $B\ra D^*$ transition at zero recoil, $F_{B\ra D^*}$. The form factor turns
out to be noticeably less than unity. The deviation of $F_{B\ra D^*}$ from
unity is larger than previously anticipated. Using our estimate we extract
$|V_{cb}|$ from the measured exclusive rate of $B\ra D^* l\nu$ extrapolated to
the point of zero recoil. The central `` exclusive" value of $|V_{cb}|$ is in
agreement with the value obtained from the inclusive semileptonic width $\Gamma
(B\ra X_c l\nu)$. We argue that the theoretical uncertainty in determining
$|V_{cb}|$ from the total inclusive width is significantly reduced if a
constraint on the quark mass difference $m_b - m_c$ stemming from the heavy
quark expansion is taken into account.


title: $A_0$ condensate in QCD

abstract:
  A survey devoted to $A_0$-condensate in gauge theories at high temperature is
presented. Both the theoretical foundations of the spontaneously generated
condensate and known methods of its calculation are discussed. As most
important consequence the SU(N) global symmetry breakdown is investigated in
details. Influence of $A_0$ on matter fields is studied in different aspects.
Some new results concerning this subject are reported as well.


title:
Dominance of the light-quark condensate in the heavy-to-light exclusive
  decays

abstract:
  Using the QCD {\it hybrid} (moments-Laplace) sum rule, we show
$semi$-$analytically$ that, in the limit $M_b \rar \infty$, the $q^2$ and $M_b$
behaviours of the heavy-to-light exclusive ($\bar B\rar \rho~(\pi)$
semileptonic as well as the $ B\rar \rho\gamma$ rare) decay--form factors are
$universally$ dominated by the contribution of the soft light-quark condensate
rather than that of the hard perturbative diagram. The QCD-analytic $q^2$
behaviour of the form factors is a polynomial in $q^2/M^2_b$, which mimics
quite well the usual pole parametrization, except in the case of the $A_1^B$
form factor, where there is a significant deviation from this polar form. The
$M_b$-dependence of the form factors expected from HQET and lattice results is
recovered. We extract with a good accuracy the ratios: $V^B(0)/A^B_1(0) \simeq
A^B_2(0)/A^B_1(0) \simeq 1.11\pm 0.01$, and $A^B_1(0)/F^B_1(0) \simeq 1.18 \pm
0.06$; combined with the ``world average" value of $f^B_+(0)$ or/and
$F^B_1(0)$, these ratios lead to the decay rates: $\Gamma_{\bar B\rar \pi e\bar
\nu} \simeq (4.3 \pm 0.7)


title: Minijets at Small x

abstract:
  Nonperturbative pomeron exchange at high energy includes minijet production.
At moderate $Q^2$ it is responsible for the small-$x$ behaviour of $\nu W_2$.
Hence minijet production should be a feature of deep inelastic scattering at
small $x$.


title: The Three-Jet Rate in \(e^{+}e^{-}\) Annihilation

abstract:
  Progress has been made on the calculation of \(R_{3}\), the three-jet rate in
\(e^{+}e^{-}\) annihilation, in the \(k_\bot \) (Durham) scheme. Using the
coherent branching formalism \cite{b,c,d}, an explicit expression for \(R_{3}\)
is calculated. In this, leading and next-to-leading large logarithms (LL and
NLL) are resummed to all orders in QCD perturbation theory. In addition to
exponentials an error function is involved.


title: Electron-Electron Scattering as a Probe of Anomalous Gauge Couplings

abstract:
  The effect of anomalous gauge couplings on polarized $e^- e^-$ scattering
cross sections is examined. It turns out that different combinations of beam
polarizations provide constraints that are complementary to each other and to
those obtained from other experiments, such as $e^+ e^-$, $e^- \gamma$ and
$\gamma \gamma$ collisions.


title:
From Kondo Model and Strong Coupling Lattice QCD to the Isgur-Wise
  Function

abstract:
  Isgur-Wise functions parametrise the leading behaviour of weak decay form
factors of mesons and baryons containing a single heavy quark. The form factors
for the quark mass operator are calculated in strong coupling lattice QCD, and
Isgur-Wise functions extracted from them. Based on renormalisation group
invariance of the operators involved, it is argued that the Isgur-Wise
functions would be the same in the weak coupling continuum theory. (Invited
talk presented at the International Colloquium on Modern Quantum Field Theory
II, TIFR, Bombay, January 5-11, 1994. To appear in proceedings.)


title: Patterns of Deviation from the Standard Model

abstract:
  Effective Lagrangians can be used to parametrize the effects of physics
beyond the standard model. Assuming the complete theory is a gauge theory, we
determine which effective operators may be generated at tree level, and which
are only generated at loop level. The latter are be suppressed by factors of
$1/ 16\pi^2$ and will therefore be quite difficult to detect. In particular,
all operators changing the Standard-Model structure of the triple-gauge-vector
couplings fall into this category. We also point out that in certain cases,
dimension-eight operators may be more important than dimension-six operators.
We discuss both the linear and non-linear representation of the Higgs sector.


title: Protecting the Baryon Asymmetry with Thermal Masses

abstract:
  We consider the evolution of baryon number $B$ in the early universe under
the influence of rapid sphaleron interactions and show that $B$ will remain
nonzero at all times even in the case of $B-L = 0$. This result arises due to
thermal Yukawa interactions that cause nonidentical dispersion relations
(thermal masses) for different lepton families. We point out the relevance of
our result to the Affleck-Dine type baryogenesis.


title:
Bounding the Tau Neutrino Magnetic Moment from Single Photon Searches at
  LEP

abstract:
  We show that single photon searches at LEP constrain the tau neutrino
magnetic moment to be less than ${\cal O}(10^{-6})~\mu_B$. This bound is
competitive with low energy ($s\simeq (30~GeV)^2$) single photon searches.


title:
Using Heavy Quark Fragmentation into Heavy Hadrons to Determine QCD
  Parameters and Test Heavy Quark Symmetry

abstract:
  We present a detailed analysis of the use of heavy quark fragmentation into
heavy hadrons for testing the heavy quark effective theory through comparison
of the measured fragmentation parameters of the $c$ and $b$ quarks. Our
analysis is entirely model independent. We interpret the known perturbative
evolution in a way useful for exploiting heavy quark symmetry at low energy. We
first show consistency with perturbative QCD scaling for measurements done
solely with $c$ quarks. We then apply the perturbative analysis and the heavy
quark expansion to relate measurements from ARGUS and LEP. We place bounds on a
nonperturbative quark mass suppressed parameter, and compare the values for the
$b$ and $c$ quarks. We find consistency with the heavy quark expansion but
fairly sizable QCD uncertainties. We also suggest that one might reduce the
systematic uncertainty in the result by not extrapolating to low $z$.


title: Commensurate Scale Relations in Quantum Chromodynamics

abstract:
  We use the BLM method to show that perturbatively-calculable observables in
QCD can be related to each other without renormalization scale or scheme
ambiguity. We define and study the commensurate scale relations. We show that
the commensurate scales satisfy the renormalization group transitivity rule
which ensures that predictions in PQCD are independent of the choice of an
intermediate renormalization scheme. We generalize the BLM procedure to higher
order. The application of this procedure to relate known physical observables
in QCD gives surprisingly simple results. In particular, the annihilation ratio
$R_{e^+e^-}$ and the Bjorken sum rule for polarized electroproduction are
related through simple coefficients, which reinforces the idea of a hidden
symmetry between these two observables.


title: Electroweak corrections to the $H\to t\bar{t}$ decay rate

abstract:
  The electroweak corrections at one-loop level to the process $H\rightarrow
t{\bar t}$ are calculated, especially the fresh top mass value announced
recently by CDF is concerned. For $M_H < 1. TeV$ where a perturbative
calculation is valid, the corrections themselves would gain a few to 20 percent
increment in the decay width as the Higgs mass $M_H$ is increasing within the
region, but they are in opposite direction to the QCD ones. If the electroweak
and QCD corrections are concerned in the meantime, the resultant decay width of
the mode yields a reduction about a few percent of the tree level one.


title: Dynamical Stability of Witten Rings

abstract:
  The dynamical stability of cosmic rings, or vortons, is investigated for the
particular equation of state given by the Witten bosonic model. It is found
that there exists a finite range of the state parameter for which the vorton
states are actually stable against dynamical perturbations. Inclusion of the
electromagnetic self action into the equation of state slightly shrinks the
stability region but otherwise yields no qualitative difference. If the Witten
bosonic model represents a good approximation for more realistic string models,
then the cosmological vorton excess problem can only be solved by assuming
either that strings are formed at low energy scales or that some quantum
instability may develop at a sufficient rate.


title:
Non Intercommuting Configurations in the Collisions of Type-I $U(1)$
  Cosmic Strings

abstract:
  It is shown that for small relative angle and kinetic energy two type I
$U(1)$ strings can form bound states upon collision instead of the more
familiar intercommuting configuration. The velocity below which this may happen
is estimated as function of the ratio of the coupling constants in the theory,
crossing angle and initial kinetic energy.


title: Interactions between $U(1)$ Cosmic Strings: An Analytical Study

abstract:
  We derive analytic expressions for the interaction energy between two general
$U(1)$ cosmic strings as the function of their relative orientation and the
ratio of the coupling constants in the model. The results are relevant to the
statistic description of strings away from critical coupling and shed some
light on the mechanisms involved in string formation and the evolution of
string networks.


title:
Hierarchical Supersymmetry Breaking in Superstring Derived
  Standard--like Models

abstract:
  We examine the problem of supersymmetry breaking in realistic superstring
standard--like models which are constructed in the free fermionic formulation.
We impose a supersymmetric vacuum at the Planck scale by requiring vanishing F
and D constraints at the cubic level of the superpotential. We then study
possible scenarios for supersymmetry breaking by examining the role of
nonrenormalizable terms and hidden sector gaugino and matter condensates. We
argue that in some scenarios hierarchical supersymmetry breaking in the
observable sector is possible.


title: Singlet quarks beyond the top at the Tevatron?

abstract:
  The first evidence for the top quark at the Tevatron may indicate a cross
section higher than the QCD expectation. We consider the possibility that
isosinglet heavy quarks may be contributing to the signal and discuss ways of
testing this possibility. For example, a charge $\case2/3$ singlet quark,
approximately degenerate and mixing with the top quark, would effectively
double the standard top signals. A charge $-\case1/3$ singlet quark mixing with
the bottom quark would not affect top signals but would generate excess
$Z+{}$multijet events with a $b$-tag.


title: Critical Bubbles and Fluctuations at the Electroweak Phase Transition

abstract:
  We discuss the critical bubbles of the electroweak phase transition using an
effective high-temperature 3-dimensional action for the Higgs field $\varphi$.
The separate integration of gauge and Goldstone boson degrees of freedom is
conveniently described in the 't Hooft-Feynman covariant background gauge. The
effective dimensionless gauge coupling $g_3(T)^2$ in the broken phase is well
behaved throughout the phase transition. However, the behavior of the one-loop
$Z(\varphi)$ factors of the Higgs and gauge kinetic terms signalizes the
breakdown of the derivative expansion and of the perturbative expansion for a
range of small $\varphi$ values increasing with the Higgs mass $m_H$. Taking a
functional $S_z[\varphi]$ with constant $Z(\varphi)=z$ instead of the full
non-local effective action in some neighborhood of the saddlepoint we are
calculating the critical bubbles for several temperatures. The fluctuation
determinant is calculated to high accuracy using a variant of the heat kernel
method. It gives a strong suppression of the transition rate compared to
previous estimates.


title: Form Factors for $B\to\pi$ and $D\to\pi$ Transitions

abstract:
  Armed with the information on the form factor $\fdpi(0)$ inferred from recent
CLEO measurements of SU(3)-breaking effects in charmed meson decays, we have
studied the form factor $\fbpi$. In the heavy quark limit, $\fbpi(q^2)$ is
related to $\fdpi(q^2)$ in the kinematic region close to zero recoil. Assuming
pole dominance for its $q^2$ dependence, $\fbpi(0)$ is estimated to be $\approx
0.39\,.$ If the requirement of heavy quark symmetry is relaxed so that it
applies only to soft pion emissions from the heavy meson, we find that
$\fbpi(0)$ is more likely of order $0.55\sim 0.60\,.$


title: Stretching Wiggly Strings

abstract:
  How does the amplitude of a wiggle on a string change when the string is
stretched? We answer this question for both longitudinal and transverse wiggles
and for arbitrary equation of state, {\it i.e.}, for arbitrary relation between
the tension $\tau$ and the energy per unit length $\epsilon$ of the string.
This completes our derivation of the renormalization of string parameters which
results from averaging out small scale wiggles on a string. The program is
presented here in its entirety.


title: On the $G_2$ Manifestation for Longitudinally Polarized

abstract:
  The contribution of the $G_2$ structure function to polarized deep inelastic
scattering is slightly redefined in order to avoid kinematical zeros. Its
strong $Q^2$-dependence implied by the Burkhardt-Cottingham (BC) sum rule
naturally explains the sign change of the generalized Gerasimov-Drell-Hearn
(GDH) sum rule. The status of the BC sum rule and implications for other spin
processes are discussed.


title: Conformal Properties of Chern-Simons Vortices in External Fields

abstract:
  The construction and the symmetries of Chern-Simons vortices in harmonic and
uniform magnetic force backgrounds found by Ezawa, Hotta and Iwazaki, and by
Jackiw and Pi are generalized using the non-relativistic Kaluza-Klein-type
framework presented in our previous paper. All Schrodinger-symmetric
backgrounds are determined.


title: Atomic Alchemy

abstract:
  We consider the transitions between electromagnetic bound states, such as the
exclusive weak decay of a muonic atom into an electronic atom: $(\mu^- Z) \to
(e^- Z) {\bar \nu_e }\nu_\mu . $ We show that relativistic effects in the
atomic wavefunctions are crucial for determining the rate. In the case of heavy
atoms, the exclusive channel branching ratios exceed $10^{-6},$ possibly
bringing the study of these rare decays within experimental reach. Such
processes thus provide a detailed laboratory for studying the high momentum
tail of wavefunctions in atomic physics; in addition, they provide a simple toy
model for investigating analogous exclusive heavy hadronic decays in quantum
chromodynamics such as $B \to \pi e \nu.$


title:
Feasibility of Beauty Baryon Polarization Measurement in Lambda0 J/psi
  Decay Channel by Atlas-LHC

abstract:
  The possibility of beauty baryon polarization measurement by cascade decay
angular distribution analysis in the channel Lambda0 J/psi --> p pi- l+ l- is
demonstrated. The error analysis shows that in the proposed LHC experiment
ATLAS at the luminosity $10^{4} pb^{-1}$ the polarization can be measured with
the statistical precision better than $\delta=0.010$ for Lambda_b0 and
$\delta=0.17$ for Xi_b0.


title: Photon Interferometry of Quark-Gluon Dynamics Revisited

abstract:
  The Bose-Einstein correlations of photons emitted {}from a longitudinally
expanding system of excited matter produced in ultrarelativistic heavy ion
collision are studied. Two effects found in recent calculations -- that the
correlation function in longitudinal direction exhibits oscillations, and that
it takes values below unity -- are demonstrated to be numerical artefacts
and/or the results of inappropriate approximations. Thus, the general quantum
statistical bounds for the two particle correlation function of a chaotic
source with Gaussian fluctuations are confirmed. Two different expressions for
the two-photon inclusive distribution are considered. Depending on which of the
two expressions is used in the calculation, the width of the correlation
function may vary by as much as $30\%$. PACS numbers: 05.30.Jp, 13.85.Hd,
25.75.+r, 12.40.Ee


title: Soft supersymmetry breaking and finiteness

abstract:
  We calculate the two-loop $\beta$-functions for soft supersymmetry-breaking
interactions in a general supersymmetric gauge theory, emphasising the role of
the evanescent couplings and masses that are generic to a non-supersymmetric
theory. We also show that a simple set of conditions sufficient for one-loop
finiteness renders a theory two-loop finite, and we speculate on the possible
significance of finite softly broken theories.


title: The Electroweak Phase Transition at $m_H \simeq m_W$

abstract:
  We study the finite temperature electroweak transition with non-perturbative
lattice Monte Carlo simulations. We find that it is of first order, at least
for Higgs masses up to 80 GeV. The critical temperature of the phase transition
is found to be smaller than that determined by a 2-loop renormalization group
improved effective potential. The jump of the order parameter at the critical
temperature is considerably larger than the perturbative value. By comparing
lattice data and perturbation theory, we demonstrate that the latter, for the
computation of the vacuum expectation value of the Higgs field $v(T)$ in the
broken phase at given temperature, converges quite well, provided $v(T)/T>1$.
An upper bound on the Higgs mass necessary for electroweak baryogenesis in the
light of the lattice data is briefly discussed.


title: Chasing the light-gluino scenario through $b\rightarrow s \gamma$

abstract:
  We investigate the impact of a light gluino, which might have escaped
detection at colliders, on inclusive radiative $B$-decays mediated through
penguin-like diagrams. We find that the viability of the scenario depends
largely on the magnitude of the flavour-violating $c$-parameter. Some
previously allowed regions of parameter space are now ruled out.


title:
QCD and Intrinsic Heavy Quark Predictions for Leading Charm and Beauty
  Hadroproduction

abstract:
  Recent experiments at Fermilab and CERN have observed a strong asymmetry
between the hadroproduction cross sections of leading $D$ mesons, containing
projectile valence quarks, and nonleading charmed mesons, without projectile
valence quarks. The observed correlations of the $\pi^{\pm} N \to D^\pm X$
cross section with the projectile charge violates the usual assumption that
heavy quark jet fragmentation factorizes. We examine the asymmetry between
leading and nonleading charm production as a function of $x_f$ and $p_T^2$
assuming a two-component model combining leading-twist fusion subprocesses and
charm production from intrinsic heavy quark Fock states. We predict a sizable
asymmetry at low $p_T^2$ and high $x_f$ from coalescence of the charm quarks
with the comoving spectator quarks of the projectile. An intrinsic $c \overline
c$ production cross section of 0.5 $\mu$b is sufficient to explain both the
magnitude and kinematic dependence of the asymmetry. In contrast, the charm jet
hadronization mechanisms contained in PYTHIA predict a sizeable leading charm
asymmetry even at low $x_F.$ The two-component model is extended to predict the
asymmetry in $B$ meson production in proton-proton and pion-proton
interactions.


title: Non-Perturbative QCD Treatment of High-Energy Hadron-Hadron Scattering

abstract:
  Total cross-sections and logarithmic slopes of the elastic scattering
cross-sections for different hadronic processes are calculated in the framework
of the model of the stochastic vacuum. The relevant parameters of this model, a
correlation length and the gluon condensate, are determined from scattering
data, and found to be in very good agreement with values coming from completely
different sources of information. A parameter-free relation is given between
total cross-sections and slope parameters, which is shown to be remarkably
valid up to the highest energies for which data exist.


title: Distinguishing Among Strong Decay Models

abstract:
  Two competing models for strong hadronic decays, the $^3P_0$ and $^3S_1$
models, are currently in use.
  Attempts to rule out one or the other have been hindered by a poor
understanding of final state interactions and by ambiguities in the treatment
of relativistic effects.
  In this article we study meson decays in both models, focussing on certain
amplitude ratios for which the relativistic uncertainties largely cancel out
(notably the $S/D$ ratios in $b_1\rightarrow\pi\omega$ and
$a_1\rightarrow\pi\rho$), and using a Quark Born Formalism to estimate the
final state interactions.
  We find that the $^3P_0$ model is strongly favoured.
  In addition, we predict a $P/F$ amplitude ratio of $1.6\pm .2$ for the decay
$\pi_2\rightarrow\pi\rho$.
  We also study the parameter-dependence of some individual amplitudes (as
opposed to amplitude ratios), in an attempt to identify a ``best'' version of
the $^3P_0$ model.


title: Testing the Principle of Equivalence by Solar Neutrinos

abstract:
  We discuss the possibility of testing the principle of equivalence with solar
neutrinos. If there exists a violation of the equivalence principle quarks and
leptons with different flavors may not universally couple with gravity. The
method we discuss employs a quantum mechanical phenomenon of neutrino
oscillation to probe into the non-universality of the gravitational couplings
of neutrinos. We develop an appropriate formalism to deal with neutrino
propagation under the weak gravitational fields of the sun in the presence of
the flavor mixing. We point out that solar neutrino observation by the next
generation water Cherenkov detectors can improve the existing bound on
violation of the equivalence principle by 3-4 orders of magnitude if the
nonadiabatic Mikheyev-Smirnov-Wolfenstein mechanism is the solution to the
solar neutrino problem.


title: Gauge Structure and Semi-Classical Aspects of Hard Thermal Loops

abstract:
  Hard thermal loops play a central role in the theory of long wavelength
excitations of a quark-gluon plasma. We show in this paper how our recent
derivation of their generating functional from the Dyson-Schwinger equations
sheds light on their semi-classical nature and their remarkable gauge
structure. In particular, we show that our kinetic equations can be written in
terms of auxiliary gauge fields with zero curvature. Remarkably, the latter
property determines entirely the dynamics in the kinematical regime of hard
thermal loops. This explains in particular why the generating functional could
have been obtained by Taylor and Wong from gauge invariance considerations. It
also clarifies the role of Chern-Simons theory in this context.


title: J/psi Production via Fragmentation at the Tevatron

abstract:
  The production of $\jpsi$ at large transverse momenta ($\pt > M_\jpsi$) in
$p\bar p$ collisions is considered by including the mechanism of fragmentation.
Both contributions of fragmentation to $\jpsi$ and of fragmentation to $\chi$
states followed by radiative decay to $\jpsi$ are taken into account. The
latter is found to be dominant and larger than direct production. The overall
theoretical estimate is shown to be nearly consistent with the experimental
observation.


title:
Test of $CP$ Violating Neutral Gauge Boson Vertices in $ e^+ e^-
  \rightarrow \gamma Z $

abstract:
  Forward-backward asymmetry in the process $e^+ e^- \rightarrow \gamma Z$ is
proposed as a test for $CP$--violating anomalous $\gamma \gamma Z$ and $ \gamma
Z Z$ couplings. Longitudinally polarized electron beams may be used to
disentangle the effects of these couplings. We estimate possible limits that
can be obtained from $e^+ e^-$ colliders at centre-of-mass energies of 200 GeV
and 500 GeV.


title: Gluon Radiation and Energy Losses in Top Quark Production

abstract:
  The emission of energetic gluons in $\tt$ production in $\ee$ annihilation
can have important experimental consequences, in particular on top quark mass
measurements. We present compact, analytical expressions for the gluon energy
distribution and its average value at first order in QCD perturbation theory.
Our results are valid for arbitrary masses, collision energies and production
currents. We pay particular attention to top quark production near threshold,
and show that in certain cases the soft gluon approximation is insufficient to
describe the radiation spectrum.


title: Disoriented Chiral Condensates

abstract:
  The idea that a bubble of misaligned vacuum is sometimes produced in
high-energy collisions is reviewed.


title: Multilepton SUSY signals from R-parity violation at the Tevatron

abstract:
  The expected trilepton signals from $p \bar p \to \chi^\pm_1\chi^0_2 \to
(\chi^0_1\ell^\pm\nu) (\chi^0_1\ell'^+\ell'^-) $ will be converted into
hadronically quiet multilepton signals, if the two final $\chi^0_1$ have
leptonic $R$-parity-violating (RPV) decays $\chi^0_1 \to \ell \ell' \nu$. We
make illustrative calculations of the acceptance for these spectacular RPV
signals, and point out that distinctive multilepton signals are possible even
when the $R$-conserving trilepton signals are blocked by the ``spoiler mode"
$\chi^0_2 \to h^0 \chi^0_1$. Other channels such as $p\bar p\to \chi_1^\pm
\chi_2^0 \to (\chi_1^0\ell^\pm\nu) (\chi_1^0\nu\nu)$, $p\bar p\to \chi_1^\pm
\chi_1^0 \to (\chi_1^0\ell\nu)\chi_1^0$ and $p\bar
p\to\chi_1^+\chi_1^-\to(\chi_1^0\ell^+\nu)(\chi_1^0\ell'^-\nu)$ can also give
quiet multileptons from RPV. We investigate these signals in the context of
supersymmetric models with radiative electroweak symmetry breaking, using
examples in the low-$\tan\beta$ $\lambda_t$ fixed-point region.


title: Theory of Pre-Asymptotic Effects in Weak Inclusive Decays

abstract:
  I give an introduction to the theory of preasymptotic effects based on the
systematic OPE/HQET expansion in $1/m_Q$ where $m_Q$ is the heavy quark mass.
The general idea is explained in two most instructive examples, with an
emphasis on pedagogical aspects. Some important results of the last year are
reviewed. In discussing the issue of the quark-hadron duality, one of the basic
ingredients of the theory, I prove that the operator product expansion {\em per
se} is an asymptotic expansion. The behavior of the high order terms in this
expansion determines the onset of duality and the accuracy of the duality
relations. The factorial divergence of the high-order terms in OPE implies a
sophisticated analytical structure in the $\alpha_s$ plane, with terms of the
type $\exp [-\exp (1/\alpha_s )]$.


title: Approximate flavor symmetries

abstract:
  We discuss the idea of approximate flavor symmetries. Relations between
approximate flavor symmetries and natural flavor conservation and democracy
models is explored. Implications for neutrino physics are also discussed.


title:
One-Loop Gauge Theory Amplitudes with an Arbitrary Number of External
  Legs

abstract:
  We review recent progress in calculations of one-loop QCD amplitudes. By
imposing the consistency requirements of unitarity and correct behavior as the
momenta of two legs become collinear, we construct ansatze for one-loop
amplitudes with an arbitrary number of external legs. For supersymmetric
amplitudes, which can be thought of as components of QCD amplitudes, the cuts
uniquely specify the amplitude.


title: On a Possible Explanation of the Origin of the Quark Mass Spectrum

abstract:
  Contrary to the usual case when the quark mass spectrum is defined by that of
the quark Yukawa couplings while the vacuum expectation value of the Higgs
field remains universal, we suggest to consider the opposite situation. Each
generation of quarks and leptons is associated with its own Higgs doublet,
while the Yukawa couplings are the same. This situation naturally arises in the
framework of finite supersymmetric Grand Unification scenario. Nondegeneracy of
the quark mass spectrum is then due to asymmetric vacuum expectation values
which spontaneously break the discrete flavour symmetry in the Higgs sector.


title:
Parton Distributions from W+- and Z Production in Polarized pp and pn
  Collisions at RHIC

abstract:
  We study the production of $W^{\pm}$ and $Z$ gauge bosons in proton-proton
and proton-neutron collisions up to a center-of-mass energy $\sqrt s=0.5\ TeV$,
in connection with the realistic possibility of having proton-deuteron
collisions at RHIC with a high luminosity. We stress the importance of
measuring unpolarized cross sections for a better determination of the flavor
asymmetry of the sea quarks. Since polarized proton beams will be available at
RHIC, we evaluate several spin-dependent observables like, double helicity
asymmetries $A_{LL}$ as a test of the sea quark polarization, double transverse
spin asymmetries $A_{TT}$ as a practical way to determine a new structure
function, the nucleon transversity distribution $h_1(x)$, and parity-violating
asymmetries $A_L$ as a further test of our present knowledge of polarized
parton distributions.


title: Introduction to Strong Higgs Sector

abstract:
  A brief introduction to strong Higgs sector i.e. the possibility of breaking
electroweak symmetry without an elementary Higgs is given. Constraints from
present LEP data are studied and the discovery potential of future colliders
investigated.


title: On the fine-tuning problem in minimal SO(10) SUSY-GUT

abstract:
  In grand unified theories (GUT) based on SO(10) all fermions of one
generation are embedded in a single representation. As a result, the top quark,
the bottom quark, and the $\tau$ lepton have a universal Yukawa coupling at the
GUT scale. This implies a very large ratio of Higgs vacuum expectation values,
$\tanb \simeq m_t/m_b$. We analyze the naturalness of such a scenario
quantitatively including all the relevant radiative corrections and find that
in minimal unified supergravity models with universal soft supersymmetry
breaking parameters at the GUT scale, the necessary amount of fine-tuning
needed is excessive. GUT threshold correction to the universal Higgs mass
parameter can significantly reduce the fine-tuning required for such large
values of $\tanb$. We also point out that the top quark mass can play a crucial
role in explaining the hierarchy between the SUSY breaking scale and the
electro-weak scale and, hence, the naturalness of large values of $\tanb$.


title: Signals for Supersymmetry at HERA

abstract:
  We consider the baryon parity signals at HERA for the case of the MSSM
production mechanisms and the decays via the lepton number violating couplings
$L_iQ{\bar D}$. We can probe very small Yukawa couplings $\lam' \gsim 3\cdot
10^{-6}$, limited only by the decay length of the LSP. We assume the LSP to be
the lightest neutralino and study its decays in detail. We present the matrix
element squared for the tree-level decay amplitude of a generally mixed
neutralino explicitly. We find that the branching fraction to charged leptons
strongly depends on the SUSY parameters and can differ significantly from the
naively expected $50\%$. The SUSY mass reaches of the studied processes in the
ZEUS detector at HERA were found to be: $(m({\tilde e}, {\tilde \nu})+m({\tilde
q}))\leq 170\gev$, $195\gev$ and $205\gev$ for the $L_\tau Q{\bar D}, L_\mu
Q{\bar D}$ and $L_e Q{\bar D}$ couplings respectively. These are well above
existing limits on R-parity violating (\rpv) SUSY from previous experiments. We
conclude that HERA offers a {\it very promising} discovery potential for \rpv\
SUSY.


title: The Gross--Llewellyn Smith Sum Rule: Theory vs Experiment

abstract:
  We describe the results of our recent work on the determination of the value
of the parameter $\Lambda_{\overline{MS}}^{(4)}$ and of the $Q^2$-dependence of
the Gross--Llewellyn Smith (GLS) sum rule from the experimental data of the
CCFR collaboration on neutrino--nucleon deep-inelastic scattering, using the
Jacobi polynomials QCD analysis. The obtained results are compared with the
information, available in the literature, information on the previous
experimental measurements of the GLS sum rule.


title: Spin, Mass, and Symmetry

abstract:
  This is a broad-brush introduction to the theory of spin in quantum field
theory, presented at the 1993 SLAC Summer Institute. It may be useful for
beginning students.


title: Yukawa textures from an extra {\bf U(1)} symmetry?

abstract:
  The observed hierarchy of the quark and lepton masses and mixing angles has
led to the parametrisation of the mass matrices in powers of the Cabibbo angle
and a certain number of zeros. The origin of these ``textures'' may lie in
symmetries present at the GUT/string unification scale. We discuss the case of
an extra $U(1)$. Symmetric textures with two or three zeros can be generated
through high-order operators containing light/heavy Higgs multiplets and
singlet fields. However, a realistic scenario for generating both the up- and
down-quark mass matrices is not possible within the MSSM with an extra singlet.
The presence of at least one pair of heavy Higgs multiplets and extra singlets
are needed, and, even so, difficulties are encountered when extending this
scenario to the neutrino sector through the mass relations of grand
unification.


title: Weight optimization in multichannel Monte Carlo

abstract:
  We discuss the improvement in the accuracy of a Monte Carlo integration that
can be obtained by optimization of the `a-priori weights' of the various
channels. These channels may be either the strata in a stratified-sampling
approach, or the several `approximate' distributions such as are used in event
generators for particle phenomenology. The optimization algorithm does not
require any initialization, and each Monte Carlo integration point can be used
in the evaluation of the integral. We describe our experience with this method
in a realistic problem, where an effective increase in program speed by almost
an order of magnitude is observed.


title: Monoslepton production in hadronic collisions

abstract:
  Single sparticle creation in high energy collisions as a consequence explicit
$R$-parity breaking, could be a rich source of highly spectacular signals at
future colliders. One particular process, which could lead to a highly exotic
leptonic signal at the LHC, is monoslepton production. In this paper we
qualitatively discuss the constraints on the signal for this process and
calculate the hadronic monoslepton production cross section, taking into
account leading QCD corrections. Our results show the leading corrections could
be quite significant at the proposed LHC operating energy.


title: $\sin 2\beta$ from $K\to\pi\nu\bar\nu$

abstract:
  We point out that the measurement of just the two branching fractions
\linebreak $B(K^+\to\pi^+\nu\bar\nu)$ and $B(K_L\to\pi^0\nu\bar\nu)$ can in a
theoretically clean manner determine $\sin 2\beta$ almost independently of
$m_t$ and $V_{cb}$. This allows to obtain an interesting relation between the
CP asymmetry $A_{CP}(\psi K_S)$ in B physics and the branching ratios for these
two rare K decays. The recently calculated next-to-leading order QCD
corrections improve the accuracy of this analysis. We find typically
$\Delta\sin 2\beta=\pm 0.11$ provided $B(\kpn)$ and $B(\klpn)$ are measured
within $\pm 10\%$ accuracy. With decreasing uncertainty in
$\Lambda_{\overline{MS}}$ and $m_c$ this error could be reduced to $\Delta\sin
2\beta < \pm 0.10$. The determination of $\sin 2\alpha$ and $\sin 2\gamma$ on
the other hand is rather poor. However respectable determinations of the
Wolfenstein parameter $\eta$ and of $\mid V_{td}\mid$ can be obtained.


title: The Physics of the Chiral Fermions

abstract:
  We review the aspects of chiral gauge theories related to the violation of
the decoupling property. The case of the top quark is worked out in detail. The
mechanism of anomaly cancellation in the low-energy effective theory is
illustrated in a simple model.


title:
Spin Alignment in the Production of Vector Mesons with Charm and/or
  Beauty via Heavy Quark Fragmentation

abstract:
  We calculate the process-independent fragmentation functions for a $\bar b$
antiquark to fragment into longitudinally and transversely polarized $B_c^*$
($^3S_1$) mesons to leading order in the QCD strong coupling constant. In the
special case of equal quark mass we recover previous results for the
fragmentation of $c\to \psi$ and $b\to\Upsilon$. Various spin asymmetry
parameters are defined as measures of the relative population of the
longitudinally and transversely polarized vector meson states. In the heavy
quark mass limit $m_b \to \infty$ our polarized fragmentation functions obey
heavy quark spin symmetry, we therefore apply them as a model to describe the
fragmentation of charm and bottom into heavy-light mesons like $D^*$ and $B^*$.
The spin asymmetry parameter, $\alpha(z)$, is consistent with the existing CLEO
data for $D^*$. The scaling behavior of $\langle z \rangle$ is studied in
detail. We find excellent agreement between the predictions of $\langle z
\rangle$ from our fragmentation functions and the experimental data for $D^*$
and $B^*$ from the LEP, CLEO, and ARGUS detectors. Finally, we also point out
that the spin asymmetry depends significantly on the transverse momentum
$p_\perp$ of the vector mesons relative to the fragmentation axis.


title:
Catalysis of Dynamical Flavor Symmetry Breaking by a Magnetic Field in
  $2+1$ Dimensions

abstract:
  It is shown that in $2+1$ dimensions, a constant magnetic field is a strong
catalyst of dynamical flavor symmetry breaking, leading to generating a fermion
dynamical mass even at the weakest attractive interaction between fermions. The
effect is illustrated in the Nambu-Jona-Lasinio model in a magnetic field. The
low-energy effective action in this model is derived and the thermodynamic
properties of the model are established. The relevance of this effect for
planar condensed matter systems is pointed out.


title: Infrared Properties of the Hot Gauge Theory after Symmetry Breaking

abstract:
  It is shown that the fictitious infrared pole is eliminated from the hot
gauge theory which acquires a new vacuum after the global gauge symmetry
spontaneously breaking. The nonzero W-condensate is generated and leads to the
screening of the chromomagnetic forces through the scenario with the standard
magnetic mass.


title:
Recalculation of W and Z radiative corrections and a top quark mass
  estimate

abstract:
  The newly published top mass prediction of 85.1 GeV conflicts with indirect
limits on the top mass, based on precision measurements interpreted by
calculations using dimensional regularization. The top quark contribution to
part of the electroweak W and Z vacuum polarization tensor is recomputed using
the symmetrical theory of generalised functions. The squared top mass
coefficient is larger by a factor 1.44. The indirect limits on the top mass
based on this computation should therefore be divided by 1.2. Further
recomputation and data analysis is needed.


title:
Quantum-Electrodynamics without renormalization V. Bosonic contributions
  to the photon mass

abstract:
  The bosonic contributions to the photon mass are shown to be of the same form
as the fermionic contributions, but of opposite sign. A mass sum rule for
bosons and fermions follows from gauge invariance. Assuming completeness of the
standard model the top quark mass can be predicted. Effectively only the
W-bosons contribute, giving a lowest order prediction of 85.1 GeV for the mass
of top quark, on the low side of currently accepted estimates.


title: Experimental Evidence for Electroweak Corrections Beyond Fermion Loops

abstract:
  We reemphasize the importance of discriminating fermion-loop and bosonic
electroweak corrections in the analysis of electroweak precision data. Most
recent data are indeed precise enough to require corrections beyond (trivial)
fermion loops. An analysis of these data in terms of the observables $\Delta x
\equiv \epsilon_{N1} - \epsilon_{N2}$, $\Delta y \equiv - \epsilon_{N2}$ and
$\epsilon \equiv - \epsilon_{N3}$ identifies the required additional
corrections as vertex corrections at the $W^\pm f\bar f^\prime$ and $Z^0 f\bar
f$ vertices. Standard-model values for these corrections are consistent with
the experimental data.


title:
Electric Quadrupole Moments of the Decuplet and the Strangeness Content
  of the Proton

abstract:
  In the SU3 Skyrme model the electric quadrupole moments of $\frac{3}{2}^+$
baryons show a strong sensitivity with respect to flavor distortions in baryon
wavefunctions. SU3 symmetric wavefunctions lead to quadrupole moments
proportional to the charge of the baryon whereas for strongly broken flavor
symmetry a proportionality to baryonic isospin emerges. Since the flavor
distortions in the wavefunctions also determine the strangeness content of the
proton the Skyrme model provides a link between both quantities.


title: Cluster Growth in Two-Dimensional Quark-Hadron Phase Transition

abstract:
  The problem of hadronic cluster production in heavy-ion collisions is studied
in search for an observable signature of first-order quark-hadron phase
transition. The study is carried out by cellular automata in a two-dimensional
model of the mixed phase at midrapidity. The clusters are allowed to grow as
well as to coalesce upon collision. The distribution of cluster sizes is found
to exhibit scaling behavior that is independent of the size of the mixed
region, nucleation radius and nucleation probability. The universal scaling
index $\gamma=1.86\pm 0.18$ may be used to characterize and identify the phase
transition process. Possible connection with self-organized criticality is
pointed out.


title: On the Strength of First Order Phase Transitions

abstract:
  Electroweak baryogenesis may solve one of the most fundamental questions we
can ask about the universe, that of the origin of matter. It has become clear
in the past few years that it also poses a multi-faceted challenge. In order to
compute the tiny primordial baryonic excess, we probably must invoke physics
beyond the standard model (an exciting prospect for most people), we must push
perturbation theory to its ``limits'' (or beyond), and we must deal with
nonequilibrium aspects of the phase transition. In this talk, I focus mainly on
the latter issue, that of nonequilibrium aspects of first order transitions. In
particular, I discuss the elusive question of ``weakness''. What does it mean
to have a weak first order transition, and how can we distinguish between weak
and strong? I argue that weak and strong transitions have very different
dynamics; while strong transitions proceed by the usual bubble nucleation
mechanism, weak transitions are characterized by a mixing of phases as the
system reaches the critical temperature from above. I show that it is possible
to clearly distinguish between the two, and discuss consequences for studies of
first order transitions in general. (Invited talk given at the ``Electroweak
Physics and the Early Universe'' workshop, Sintra, March 23-25, 1994.)


title: An Alternative Method of Extracting $V_{bu}$ from Semi-leptonic B Decay

abstract:
  We propose a new method of extracting $V_{bu}$ from measurements of
Semi-leptonic B decay which has much less theoretical uncertainties than
conventional methods.


title: Baryons with Many Colors and Flavors

abstract:
  Using recently-developed diagrammatic techniques, I derive some general
results concerning baryons in the $1/N$ expansion, where $N$ is the number of
QCD colors. I show that the spin-flavor relations which hold for baryons in the
large-$N$ limit, as well as the form of the corrections to these relations at
higher orders in $1/N$, hold even if $N_F / N \sim 1$, where $N_F$ is the
number of light quark flavors. I also show that the amplitude for a baryon to
emit $n$ mesons is $O(1 / N^{n / 2 - 1})$, and that meson loops attached to
baryon lines are unsupressed in the large-$N$ limit, independent of $N_F$. For
$N_F > 2$, there are ambiguities in the extrapolation away from $N = 3$ because
the baryon flavor multiplets for a given spin grow with $N$. I argue that the
$1/N$ expansion is valid for baryons with spin $O(1)$ and {\it arbitrary}
flavor quantum numbers, including e.g. baryons with isospin and/or strangeness
$O(N)$. This allows the formulation of a large-$N$ expansion in which it is not
necessary to identify the physical baryons with particular large-$N$ states.
$SU(N_F)$ symmetry can be made manifest to all orders in $1/N$, yet group
theory factors must be evaluated explicitly only for $N_F = N = 3$. To
illustrate this expansion, I consider the non-singlet axial currents, baryon
mass splittings, and matrix elements of $\mybar ss$ and $\mybar s \gam_\mu
\gam_5 s$ in the nucleon.


title: Baryon Magnetic Moments in a Simultaneous Expansion in $1/N$ and $m_s$

abstract:
  We consider the baryon octet and decuplet magnetic moments in a simultaneous
expansion in $m_s$ and $1/N$ taking $N_F / N \sim 1$, where $N$ is the number
of QCD colors and $N_F$ is the number of light quark flavors. At leading order
in this expansion, the magnetic moments obey the non-relativistic quark-model
relations. We compute corrections to these relations using an effective
lagrangian formalism which respects chiral symmetry to all orders in the $1/N$
expansion. Including corrections up to order $m_s^{1/2}$, we find 8 relations
among the 9 measured octet and decuplet magnetic moments; including corrections
up to order $1/N$ and $m_s$, we find 4 remaining relations. The relations work
well, and suggest that the expansion is under control. We give predictions for
the unmeasured decuplet magnetic moments.


title: Constraints on the momentum dependence of rho-omega mixing

abstract:
  Within a broad class of models we show that the amplitude for rho^0-omega
mixing must vanish at the transition from timelike to spacelike four momentum.
Hence in such models the mixing is either zero everywhere or is necessarily
momentum-dependent. This lends support to the conclusions of other studies of
rho-omega mixing and calls into question standard assumptions about the role of
rho-omega mixing in the theoretical understanding of charge-symmetry breaking
in nuclear systems.


title:
Parameter free calculation of non-resonant three body decays of charmed
  mesons in a weak gauged U(4)_L x U(4)_R Chiral Lagrangian Model

abstract:
  Non--resonant decays of charmed mesons into three pseudoscalars are analyzed
in a weak gauged $U(4)_L \otimes U(4)_R$ chiral lagrangian model. The
calculation is free of unknown parameters and only requires the masses of
pseudoscalar mesons as hadronic inputs. When comparison with experimental data
is possible we find that in some processes we have good agreement and in others
we are an order of magnitude below. This may be due to the absence in our
calculation of final state interactions, presumably important here, and the
manifest difficulty in extracting the non--resonant contribution from an
experimental point of view.


title: When is a Higgs THE Higgs?

abstract:
  The one-Higgs-doublet standard model is necessarily incomplete because of the
triviality of the scalar symmetry-breaking sector. If the Higgs mass is
approximately 600 GeV or higher, there must be additional dynamics at a scale
$\Lambda$ which is less than a few TeV. In this case the properties of the
Higgs resonance can differ substantially from those predicted by the standard
model. In this talk we construct an effective Lagrangian description of a
theory with a non-standard Higgs boson and analyze the features of a theory
with such a resonance coupled to the Goldstone Bosons of the breaking of $\su$.


title: CP-Like Symmetry, Family Replication, Charge Quantization

abstract:
  We propose that the physics beyond the standard Weinberg-Salam model is such
that matter and the CP conjugate anti-matter fields have the same set of
charges with respect to the various force groups (upto ordering). We show that
this CP-like symmetry leads to an understanding of family replication. We use
anomaly constraints to infer the fermion spectra that lead to automatic
electric charge quantization. We also find that the unification of coupling
constants is possible at $M_{U} = 2 \times 10^{15} GeV$.