title:
Exact Nonperturbative Unitary Amplitudes for 1->8 Transitions in a Field
  Theoretic Model

abstract:
  We present a quantum mechanical model with an infinite number of (discrete)
degrees of freedom, which can serve as a laboratory for multiparticle
production in a collision. There is a cubic coupling between modes without,
however, any problems associated with unstable ground states. The model is
amenable to precise numerical calculations of nonperturbative 1->N transition
amplitudes. On an ordinary workstation, time and memory limitations effectively
restrict N to be $\le\ 8,$ and we present results for this case. We find (1)
that there is reasonable period of time for which there is a constant rate for
the 1->8 transition; (2) at the end of the linear period, the eight particle
amplitude attains a maximum value $\aemax$ which is about $3-4$ orders of
magnitude larger than the comparable amplitude for excitation of the $N=8$
state in the anharmonic oscillator; (3) for values of the coupling in the
region where the Born approximation fails, the amplitude is much larger than
the naive estimates $A_8\simeq \exp{(-1/\g2)}\ $ or $\ \exp{(-8)};$ it is more
like $A_8\sim\exp{(-0.20/\g2)}.$


title: Walking Technicolor and Electroweak Radiative Corrections

abstract:
  We examine the effect of walking technicolor dynamics on the electroweak $S$
parameter and contrast it with the effect of QCD-like technicolor dynamics. Our
main tools are the operator product expansion for the high-momentum behavior of
the electroweak gauge boson vacuum polarizations and the analyticity of these
polarizations which relate their low and high momentum behaviors. We show that
whereas in large QCD-like technicolor models $S$ is large and positive, in
walking technicolor models a negative contribution is emphasized, related to
the large anomalous dimension of the technifermion condensate. Thus in walking
technicolor $S$ is determined by a large cancellation of two competing effects.
This may result in much smaller values of $S$ than in QCD-like technicolor,
although considerable uncertainties are involved. We conclude that it is
impossible to rule out walking technicolor based on the present experimental
limits on $S$ and the present theoretical technology.


title: Fixing the Top-Quark and Higgs-Boson Masses

abstract:
  If the quadratic divergence of the standard electroweak model and its local
variation with mass scale are both assumed to be zero, then a modified one-loop
calculation yields m_t = 117 GeV and m_H = 183 GeV. Such a scenario may be the
result of an underlying theory to be revealed at a much higher mass scale.


title: On the phase transition in the scalar theory

abstract:
  The basic tool for the study of the electroweak phase transition is $V_{eff}
(\phi,T)$, the one-loop finite-temperature effective potential, improved by
all-loop resummations of the most important infrared contributions. In this
paper we perform, as a first step towards a full analysis of the Standard Model
case, a detailed study of the effective potential of the scalar theory. We show
that subleading corrections to the self-energies lead to spurious terms, linear
in the field-dependent mass $m(\phi)$, in the daisy-improved effective
potential. Consistency at subleading order requires the introduction of
superdaisy diagrams, which prevent the appearance of linear terms. The
resulting $V_{eff}(\phi,T)$ for the scalar theory hints at a phase transition
which is either second-order or very weakly first-order.


title:
Implications of New Gallex Results for the MSW Solution of the Solar
  Neutrino Problem

abstract:
  We compare the implications for 7Be and pp neutrinos of the two MSW fits to
the new GALLEX solar neutrino measurements . Small mixing angle solutions tend
to suppress the former as electron-neutrinos, but not the latter, and large
angle solutions tend to reduce both by about a factor of 2. The consequences
for BOREXINO and similar solar neutrino--electron scattering experiments are
discussed.


title: Semilocal Topological Defects

abstract:
  Semilocal defects are those formed in field theories with spontaneously
broken symmetries, where the vacuum manifold $M$ is fibred by the action of the
gauge group in a non-trivial way. Studied in this paper is the simplest such
class of theories, in which $M\simeq S^{2N-1}$, fibred by the action of a local
$U(1)$ symmetry. Despite $M$ having trivial homotopy groups up to $\pi_{2N-2}$,
this theory exhibits a fascinating variety of defects: vortices, or semilocal
strings; monopoles (on which the strings terminate); and (when $N=2$) textures,
which may be stabilised by their associated magnetic field to produce a
skyrmion.


title: Chiral Perturbation Theory for SU(3) Breaking in Heavy Meson Systems

abstract:
  The SU(3) breaking effects due to light quark masses on heavy meson masses,
decay constants ($F_{D}, F_{D_{s}}$) and the form factor for semileptonic
$\overline{B}\rightarrow D^{(\ast)} l\bar{\nu}_{l}$ transitions are formulated
in chiral perturbation theory, using a heavy meson effective Lagrangian and
expanding in inverse powers of the heavy meson mass. To leading order in this
expansion, the leading chiral logarithms and the required counterterms are
determined. At this level, a non-analytic correction to the mass splittings of
${\cal O}(p^3)$ appears, similar the the one found in light baryons. The
correction to $F_{D_{s}}/F_{D}$ is roughly estimated to be of the order of
$10\%$ and, therefore, experimentally accessible, while the correction to the
form factor is likely to be substantially smaller. We explicitly check that the
heavy quark symmetry is preserved by the chiral loops.


title:
Accidental Approximate Generation Universality and its Possible
  Verification

abstract:
  The universality of $e-\mu-\tau$ interactions may only be an accidental
approximate symmetry analogous to that of flavor SU(2) and SU(3). This was
specifically realized by an extension of the standard model proposed in 1981.
Two key predictions are that the $\tau$ lifetime should be longer and that the
$\rho$ parameter measured at the Z peak should have an additional negative
contribution. These are consistent with present precision electroweak
measurements. A future decisive test of this model would be the discovery of
new W and Z bosons with nearly degenerate masses of a few TeV.


title: Superconducting Cosmc Strings and Primordial Magnetic Fields

abstract:
  We consider grand unified theories with superconducting cosmic strings and
which admit the mechanism for generating primordial magnetic fields recently
discussed by Vachaspati. We show that these models are severely constrained by
cosmological arguments. Quite generically, either stable springs or vortons
will form. Provided the mass per unit length of the strings is sufficiently
large, these stable configurations will overclose the Universe.


title: The Implications of the COBE-DMR Results for Cosmic Strings

abstract:
  We compare the anisotropies in the cosmic microwave background radiation
measured by the COBE experiment to the predictions of cosmic strings. We use an
analytic model for the $\Delta T/T$ power spectrum that is based on our
previous numerical simulations to show that the COBE results imply a value for
the string mass per unit length, $\mu$ under the assumption that cosmic strings
are the source of the measured anisotropy. We find $G\mu = 1.5\pm 0.5 \times
10^{-6}$ which is consistent with the value of $\mu$ thought to be required for
cosmic strings to seed galaxy formation.


title: Hopf Textures

abstract:
  A Hopf texture is a vacuum field configuration of isovector fields which is
an onto map from the space as a large three sphere to the vacuum manifold
$S^2$. We construct a Hopf texture with spherically symmetric energy density
and discuss the topological charge. A Hopf texture collapses, and we study the
collapse process numerically. In our simulations, it is clear that a Hopf
texture does not decay into a pair of monopoles. We also argue that the
probability of forming Hopf textures in random processes is very small compared
to that of global monopoles.


title: Corrections to the Electroweak Effective Action at Finite Temperature

abstract:
  We calculate contributions to the finite temperature effective action for the
electroweak phase transition (EWPT) at $\O(g^4)$, {\it i.e.} at second order in
$(g^2 T/\M)$ and all orders in $(g^2 T^2/\M^2)$. This requires plasma-mass
corrections in the calculation of the effective potential, inclusion of the
``lollipop'' diagram, and an estimate of derivative corrections. We find the
EWPT remains too weakly first-order to drive baryogenesis. We calculate some
one loop kinetic energy corrections using both functional and diagrammatic
methods; these may be important for saddlepoint configurations such as the
bounce or sphaleron.


title:
Nambu Jona-Lasinio Like Models and the Low Energy Effective Action of
  QCD

abstract:
  We present a derivation of the low energy effective action of an extended
Nambu Jona-Lasinio (ENJL) model to $O(p^4)$ in the chiral counting. Two
alternative scenarios are considered on how the ENJL model could originate as a
low energy approximation to QCD. The low energy effective Lagrangian we derive
includes the usual pseudoscalar Goldstone modes, as well as the lower scalar,
vector and axial-vector degrees of freedom. By taking appropriate limits, we
recover most of the effective low-energy models discussed in the literature; in
particular the gauged Yang-Mills vector Lagrangian, the Georgi-Manohar
constituent quark-meson model, and the QCD effective action approach model.
Another property of the ensuing effective Lagrangian is that it incorporates
most of the short-distance relations which follow from QCD. (We derive these
relations in the presence of all possible gluonic interactions to leading order
in the $1/N_c$-expansion.) Finally the numerical predictions are compared to
the experimental values of the low energy parameters


title: Perturbative QCD Corrections to the Soft Pomeron

abstract:
  We study the interface between soft and hard QCD at high energy and small
momentum transfer. At LHC and SSC energies, we find that a cutoff BFKL equation
leads one to expect a measurable perturbative component in traditionally soft
processes. We show that the total cross section could become as large as 175 mb
(122 mb) and the rho parameter 0.40 (0.25) at the SSC (LHC).


title: Comment On ``Grand Unification and Supersymmetric Threshold"

abstract:
  Barbieri and Hall have argued that threshold effects at the scale of
grand-unification wipe out predictions on the SUSY scale, M_S. Using triviality
arguments we give upper bounds on ultraheavy particles, while proton stability
gives lower bounds on the mass of the higgs color-triplet. We find no useful
lower bound on the $\Sigma$ supermultiplet, but if the strong coupling constant
is as large as recent experiments suggest, unification in the minimal SUSY
SU(5) model requires that the $Sigma$ masses be $\sim 10^{-7}M_V$ and that the
color octet and weak triplet be split in mass by a factor of $\sim$100.


title: Gauge Dependence of the Resummed Thermal Gluon Self Energy

abstract:
  The gauge dependence of the hot gluon self energy is examined in the context
of Pisarski's method for resumming hard thermal loops. Braaten and Pisarski
have used the Ward identities satisfied by the hard corrections to the n-point
functions to argue the gauge fixing independence of the leading order resummed
QCD plasma damping rate in covariant and strict Coulomb gauges. We extend their
analysis to include all linear gauges that preserve rotational invariance and
display explicitly the conditions required for gauge fixing independence. It is
shown that in covariant gauges the resummed damping constant is gauge fixing
independent only if an infrared regulator is explicitly maintained throughout
the calculation.


title:
Finite Temperature Renormalization of the $(\phi^3)_6$- and
  $(\phi^4)_4$-Models at Zero Momentum

abstract:
  A self-consistent renormalization scheme at finite temperature and zero
momentum is used together with the finite temperature renormalization group to
study the temperature dependence of the mass and the coupling to one-loop order
in the $(\phi^3)_6$- and $(\phi^4)_4$-models. It is found that the critical
temperature is shifted relative to the naive one-loop result and the coupling
constants at the critical temperature get large corrections. In the high
temperature limit of the $\phiff$-model the coupling decreases.


title: Strong Decays of Excited Heavy Mesons In Chiral Perturbation Theory

abstract:
  We construct an effective Lagrangian describing the interaction of soft pions
and kaons with mesons containing a heavy quark and light degrees of freedom in
an orbital $p$ wave. The formalism is easily extended to heavy mesons and
baryons in arbitrary excited states. We calculate the leading contributions to
the strong decays $\dtwo\to\d\pi$, $\dtwo\to\dstar\pi$ and $\done\to\dstar\pi$.
We confirm the relations between the rates previously obtained by Isgur and
Wise using heavy quark symmetry, and find that the absolute widths are
consistent with na\"\i ve power counting. We also estimate the branching ratios
for the two pion decays $\dtwo\to\dstar\pi\pi$, $\done\to\dstar\pi\pi$ and
$\done\to\d\pi\pi$, which are dominated by pole graphs. Our predictions depend
on the masses and widths of the as yet unseen scalar-pseudovector $p$-wave
doublet. Heavy quark spin symmetry predicts $\Gamma(\dtwo\to\dstar\pi\pi):
\Gamma(\done\to\dstar\pi\pi):\Gamma(\done\to\d\pi\pi)=3:1:2$, but this relation
is badly violated in practice because $1/M$ effects arising purely from
kinematics are large.


title: $SU(3)\otimes U(1)$ Model for Electroweak Interactions

abstract:
  We consider a gauge model based on $SU(3)\otimes U(1)$ symmetry in which the
lepton number is violated explicitly by charged scalar and gauge bosons,
including a vector field with double electric charge.
  Although there exist in the literature several models based on a
$SU(3)\otimes U(1)$ gauge symmetry, our model has a different representation
content and a quite different new physics at an, in principle, arbitrary mass
scale.
  This is possibly the simplest way to enlarge the gauge group $SU_L(2)\otimes
U_Y(1)$ in order to have doubly charged gauge bosons, without losing the
natural features of the standard electroweak model. The price we must pay is
the introduction of exotic quarks, with electric charge $5/3$ and $-4/3$.
  A previous version of the model was considered several months ago concerning
the possibility that in this kind of models neutrinoless double beta decay
proceeds even for massless neutrinos and with scalar exchange instead of vector
exchange.
  Our work is in press in Physical Review D.


title: Complex Effective Potentials and Critical Bubbles

abstract:
  The Higgs contribution to the effective potential appears to be complex. How
do we interpret this, and how should we modify the calculation to calculate
physical quantities such as the critical bubble free energy?


title: Dilepton Production in $e^- p$ and $e^+ e^-$ Colliders

abstract:
  In an $e^- p$ collider, a striking signature for a dilepton gauge boson is
\ep \ ; this cross-section is calculated by using the helicity amplitude
technique. At HERA, with center-of-mass energy $\sqrt s = 314 GeV$, a dilepton
mass above $150 GeV$ is inaccessible but at LEPII-LHC, with a center-of-mass
energy $\sqrt s = 1790 GeV $, masses up to 650 GeV can be discovered. In an
$e^+ e^-$ collider, the signature is \ee \ . The cross-sections of this process
are also calculated for the center-of-mass energies $\sqrt s = 200, 500$ and
$1000 GeV$.


title: Remarks on the Electroweak Phase Transition

abstract:
  In the standard scenario, the electroweak phase transition is a first order
phase transition which completes by the nucleation of critical bubbles.
Recently, there has been speculation that the standard picture of the
electroweak phase transition is incorrect. Instead, it has been proposed that
throughout the phase transition appreciable amounts of both broken and unbroken
phases of $SU(2)$ coexist in equilibrium. I argue that this can not be the
case. General principles insure that the universe will remain in a homogenous
state of unbroken $SU(2)$ until the onset of critical bubble production.
  In addition, an analytic treatment of the one Higgs doublet, electroweak
phase transition in the standard model and minimal extensions is reviewed.
Results from the thin wall approximation are compared to results obtained using
the Lindes' action. Perhaps the most important quantitative result we can get
from an analysis of the phase transition is determination of $\vevphi$ when the
phase transition completes. For Higgs boson masses above the current
experimental limit, the thin wall approximation determines the value of
$\vevphi$ at the end of the phase transition to an accuracy of better than
three percent.


title: Structure Function Approach to Vector-Boson Scattering in pp Collisions

abstract:
  We discuss weak-vector-boson scattering, at next-to-leading order in QCD,
within the framework of hadronic structure functions. We use this approach to
calculate the Higgs-boson production cross section via vector-boson fusion at
the LHC/SSC; we find a modest increase over the leading-order prediction. We
also give expressions for the distribution of vector bosons in a proton
(effective-$W$ approximation) including ${\cal O} (\alpha_s)$ corrections.


title: Light Quark Masses and Quarkonium Decays

abstract:
  After discussing the intrinsic ambiguity in determining the light quark mass
ratio $m_u/m_d$, we reexamine the recent proposal that this ambiguity can be
resolved by applying the QCD multipole expansion for the heavy quarkonium
decays. It is observed that, due to instanton effects, some matrix elements
which have been ignored in previous works can give a significant contribution
to the decay amplitudes, which results in a large uncertainty in the value of
$m_u/m_d$ deduced from quarkonium phenomenology. This uncertainty can be
resolved only by a QCD calculation of some second order coefficients in the
chiral expansion of the decay amplitudes.


title: Mass of Pseudoscalar Gluonium: A Higher-Loop QCD Sum-Rule Estimate

abstract:
  Higher-loop corrections to the pseudoscalar ($0^{-+}$) gluonium correlation
function will be used to obtain the leading gluon condensate contributions to
the subtraction-independent QCD sum-rules. The effect of these higher-loop
corrections on the sum-rule estimates of the pseudoscalar gluonium mass will be
investigated. The final results of this analysis compare favourably with
$SU(3)$ lattice simulations.


title: Inelastic Channels in the Electroweak Symmetry-Breaking Sector

abstract:
  It has been argued that if light Higgs bosons do not exist then the
self--interactions of $W$'s become strong in the TeV region and can be observed
in longitudinal $WW$ scattering. We present a model with many inelastic
channels in the $WW$ scattering process, corresponding to the creation of heavy
fermion pairs. The presence of these heavy fermions affects the elastic
scattering of $W$'s by propagating in loops, greatly reducing the amplitudes in
some charge channels. Consequently, the symmetry--breaking sector cannot be
fully explored by using, for example, the $W^+W^+$ mode alone; all $WW
\rightarrow WW$ scattering modes must be measured.}


title: Dynamical Self-mass for Massive Quarks

abstract:
  We examine dynamical mass generation in QCD with large current mass quarks. A
renormalization group analysis is performed to separate fermion self-mass into
a dynamical and a kinematical part. It is shown that the energy scale og the
Schwinger-Dyson (SD) equation and the effective gauge coupling are fixed by the
current mass. The dynamical self-mass satisfies a homogeneous SD equation which
has a trivial solution when the current mass exceeds a critical value. We
therefore suggest that the quark condensate, as the function of the current
mass, observes a local minimum around 2.7\Lambda_(QCD).


title: Comments on the Vacuum Orientations in QCD

abstract:
  We study the QCD vacuum orientation angles in correlation with the strong CP
phases. A vacuum alignment equation of the dynamical chiral symmetry breaking
is derived based on the anomalous Ward identity. It is emphasized that a chiral
rotation of the quark field causes a change of the vacuum orientation and a
change in the definition of the light pseudoscalar generators. As an
illustration of the idea, $\h\rightarrow 2\p$ decays are carefully studied in
different chiral frames. Contrary to the claim in Ref.[7], the $\theta$-term
does not directly contribute to the CP-violating processes.


title:
A Comprehensive Coordinate Space Renormalization of Quantum
  Electrodynamics to 2-Loop Order

abstract:
  We develop a coordinate space renormalization of massless Quantum
Electrodynamics using the powerful method of differential renormalization. Bare
one-loop amplitudes are finite at non-coincident external points, but do not
accept a Fourier transform into momentum space. The method provides a
systematic procedure to obtain one-loop renormalized amplitudes with finite
Fourier transforms in strictly four dimensions without the appearance of
integrals or the use of a regulator. Higher loops are solved similarly by
renormalizing from the inner singularities outwards to the global one. We
compute all 1- and 2-loop 1PI diagrams, run renormalization group equations on
them and check Ward identities. The method furthermore allows us to discern a
particular pattern of renormalization under which certain amplitudes are seen
not to contain higher-loop leading logarithms. We finally present the
computation of the chiral triangle showing that differential renormalization
emerges as a natural scheme to tackle $\gamma_5$ problems.


title: Wightman Functions in QCD

abstract:
  The constraint imposed by Gauss' law is used to show that the matrix elements
of n-point Wightman Functions of gluon field and quark current operators at
different space time points vanish when taken between physical states.


title: Can the Electroweak Symmetry-breaking Sector Be Hidden?

abstract:
  In a recent paper, Chivukula and Golden claimed that the electroweak
symmetry--breaking sector could be hidden if there were many inelastic channels
in the longitudinal $WW$ scattering process. They presented a model in which
the $W$'s couple to pseudo--Goldstone bosons, which may be difficult to detect
experimentally. Because of these inelastic channels, the $WW$ interactions do
not become strong in the TeV region. We demonstrate that, despite the reduced
$WW$ elastic amplitudes in this model, the total event rate ($\sim 5000$ extra
longitudinal $W^+W^-$ pairs produced in one standard SSC year) does not
decrease with an increasing number of inelastic channels, and is roughly the
same as in a model with a broad high--energy resonance and no inelastic
channels.


title: The Phenomenology of a Hidden Symmetry Breaking Sector

abstract:
  We calculate the production rate of gauge-boson pairs at the SSC in a model
with a ``hidden'' electroweak symmetry breaking sector. We show that the signal
of electroweak symmetry breaking is lower than the background and that we
cannot necessarily rely on gauge boson pairs as a signal of the dynamics of
symmetry breaking.


title: Seesaw Neutrino Mass Ratios with Radiative Corrections

abstract:
  In the canonical up-quark seesaw, the ratios of light neutrino masses are
more easily predicted than the masses themselves. Under explicitly enumerated
neccesary but minimal assumptions, these ratios are obtained, including
radiative corrections. The predictions remain uncertain only by the top quark
mass and triviality mass limit, and the power law of the seesaw. The tau
neutrino is specially affected by the non-linear effect of the heavy top quark
mass. The derived ratios have application to solar, atmospheric, and
cosmological neutrinos and laboratory neutrino oscillation searches. The seesaw
with charged lepton masses instead is briefly considered. Submitted to Phys
Lett B.


title:
Radiative corrections to the Higgs boson decay rate $\Gamma(H\rightarrow
  ZZ)$ in the minimal supersymmetric model

abstract:
  We consider radiative corrections to the decay rate $\Gamma(H\rightarrow ZZ)$
of the heavy {\it CP}-even Higgs boson of the minimal supersymmetric model to
two $Z$ bosons. We perform a one loop Feynman diagram calculation in the
on-mass-shell renormalization scheme, and include the third generation of
quarks and squarks. The tree level rate is suppressed by a mixing angle factor
and decreases as $1/M_H$ for large $M_H$. The corrected rate overcomes this
suppression and increases with $M_H$ for $M_H > 500$~GeV. The corrections can
be very large and depend in detail on the top squark masses and $A$-term, as
well as the supersymmetric Higgs mass parameter $\mu$.


title: Probing New Gauge Boson Couplings at Hadron Supercolliders

abstract:
  Once it is discovered, the determination of the various couplings of a new
neutral gauge boson at a hadron supercollider will not be an easy task. We
review several recent studies that have begun to examine this issue for both
the SSC and LHC.


title: Progress in the Theory of the Electroweak Phase Transition

abstract:
  Recent progress in the theory of the electroweak phase transition is
discussed. For the Higgs boson mass smaller than the masses of W and Z bosons,
the phase transition is of the first order. However, its strength is
approximately 2/3 times less than what follows from the one-loop approximation.
This rules out baryogenesis in the minimal version of the electroweak theory
with light Higgs bosons. The possibility of the strongly first order phase
transition in the theory with superheavy Higgs bosons is considered.
  We show that if the Yang-Mills field at high temperature acquires a magnetic
mass $\sim g^2 T$, then no linear terms appear in the effective potential in
all orders of perturbation theory and the symmetry in gauge theories at high
temperatures is actually restored. Even though the last statement was never
questioned by most of the authors, it was extremely difficult to come to a
reliable conclusion about it due to the infrared problem in thermodynamics of
non-Abelian gauge fields.
  The phase transition occurs due to production and expansion of critical
bubbles. A general analytic expression for the probability of the bubble
formation is obtained, which may be used for study of tunneling in a wide class
of theories.


title: Electroweak Baryogenesis with a Second Order Phase Transition

abstract:
  If stable electroweak strings are copiously produced during the electroweak
phase transition, they may contribute significantly to the presently observed
baryon to entropy ratio of the universe. This analysis establishes the
feasibility of implementing an electroweak baryogenesis scenario without a
first order phase transition.


title: Vector-Boson versus Gluon Fusion at Hadron Colliders

abstract:
  We use chiral perturbation theory to show that pseudo-Goldstone boson
scattering and gluon fusion probe different aspects of electroweak symmetry
breaking at hadron colliders. In particular, the physics responsible for
unitarizing the lowest-order pseudo-Goldstone boson scattering amplitudes need
not significantly affect the gluon fusion process. We first show this within
the context of strict chiral perturbation theory, and then discuss it using the
language of resonances.


title:
Using Back-Scattered Laser Beams to Detect CP Violation in the Neutral
  Higgs Sector

abstract:
  We demonstrate that the ability to polarize the photons produced by
back-scattering laser beams at a TeV scale linear $\epem$ collider could make
it possible to determine whether or not a neutral Higgs boson produced in
photon-photon collisions is a CP eigenstate. The relative utility of different
types of polarization is discussed. Asymmetries that are only non-zero if the
Higgs boson is a CP mixture are defined, and their magnitudes illustrated for a
two-doublet Higgs model with CP-violating neutral sector.


title: Magnetic Monopoles As a New Solution to Strong CP Problem

abstract:
  A non-perturbative solution to strong CP problem is proposed. It is shown
that the gauge orbit space with gauge potentials and gauge tranformations
restricted on the space boundary in non-abelian gauge theories with a $\theta$
term has a magnetic monopole structure if there is a magnetic monopole in the
ordinary space. The Dirac's quantization condition in the corresponding quantum
theories ensures that the vacuum angle $\theta$ in the gauge theories must be
quantized. The quantization rule is derived as $\theta=2\pi/n~(n\neq 0)$ with n
being the topological charge of the magnetic monopole. Therefore, we conclude
that the strong CP problem is automatically solved non-perturbatively with the
existence of a magnetic monopole of charge $\pm 1$ with $\theta=\pm 2\pi$. This
is also true when the total magnetic charge of monopoles are very large
($|n|\geq 10^92\pi$) if it is consistent with the abundance of magnetic
monopoles. This implies that the fact that the strong CP violation can be only
so small or vanishing may be a signal for the existence of magnetic monopoles.


title: On the Origin of Fermion Masses

abstract:
  We review some recent work on nonperturbative properties of fermions and
connections with chiral gauge theories. In particular, we consider one of the
ultimate goals of this program: the understanding of the actual fermion mass
spectrum. It is pointed out that if quarks and leptons are composite, their
masses may be set by the physics of the preons and their interactions in such a
manner as to differ considerably from the Yukawa form $m_f \propto v$ (where
$v$ is the electroweak symmetry breaking scale) or analogous forms involving
$v$. Some ideas of how this might work are given, and some implications are
discussed.


title:
Global Quantization in Gauge Orbit Space with Magnetic Monopoles As a
  Solution to Strong CP Problem and the Relevance to $U_A(1)$ Problem

abstract:
  We generalize our discussions and give more general physical applications of
a new solution to the strong CP problem with magnetic monopoles as originally
proposed by the author$^1$. Especially, we will discuss about the global
topological structure in the relevant gauge orbit spaces to be clarified. As it
is shown that in non-abelian gauge theories with a $\theta$ term, the induced
gauge orbit space with gauge potentials and gauge functions restricted on the
space boundary $S^2$ has a magnetic monopole structure and the gauge orbit
space has a vortex structure if there is a magnetic monopole in the ordinary
space. The Dirac's quantization conditions in the quantum theories ensure that
the vacuum angle $\theta$ in the gauge theories must be quantized. The
quantization rule is given by $\theta=2\pi/n~(n\neq 0)$ with n being the
topological charge of the magnetic monopole. Therefore, the strong CP problem
is automatically solved in the presence of a magnetic monopole of charge $\pm
1$ with $\theta=\pm 2\pi$, or magnetic monopoles of very large total
topological charge ($|n|\geq 10^92\pi$) if it is consistent with the abundance
of magnetic monopoles. Where in the first case with a magnetic monopole of
topological charge 1 or -1, we mean the strong CP-violation can be only very
small by the measurements implemented so far. Since $\theta=\pm 2\pi$
correspond to different monopole sectors, the CP can not be conserved exactly
in strong interactions in this case. In the second case, the strong CP cannot
be conserved either for large but finite n. The fact that the strong
CP-violation measured so far can be only so small or vanishing may be a signal
for the existence of magnetic monopoles. We also conjecture that the parity
violation and CP violation in weak interaction fundamentally may intimately


title: Baryogenesis Constraints on the Minimal Supersymmetric Model

abstract:
  Requirement that the vacuum expectation values of Higgs fields immediately
after the phase transition be large enough imposes constraints upon the
parameters of the minimal supersymmetric model. In particular, one obtains the
upper bound on the lighter CP-even Higgs mass and the soft supersymmetry
breaking scale for different values of the top quark mass.


title: Particle Physics Summary, Where are We and Where are We Going?

abstract:
  The XXVII$^{\rm th}$ Rencontres de Moriond featured approximately 84 talks on
a wide range of topics. I will try to summarize the highlights under the
hypothesis that $SU_3 \x SU_2 \x U_1$ is correct to first approximation,
concentrating on probes for new physics at various scales.


title: Dilatonic Domain Walls

abstract:
  Eq.(19) is added and related issues are further clarified. Also some typos
and signs a re corrected.


title: Non--decoupling, triviality and the $\rho$ parameter

abstract:
  The dependence of the $\rho$ parameter on the mass of the Higgs scalar and
the top quark is computed non--perturbatively using the $1/N_F$ expansion in
the standard model. We find an explicit expression for the $\rho$ parameter
that requires the presence of a physical cutoff. This should come as no
surprise since the theory is presumably trivial. By taking this cutoff into
account, we find that the $\rho$ parameter can take values only within a
limited range and has finite ambiguities that are suppressed by inverse powers
of the cutoff scale, the so called ``scaling--violations". We find that large
deviations from the perturbative results are possible, but only when the cutoff
effects are also large.


title: Thermal Hadron Production in High Energy Heavy Ion Collisions

abstract:
  We provide a method to test if hadrons produced in high energy heavy ion
collisions were emitted at freeze-out from an equilibrium hadron gas. Our
considerations are based on an ideal gas at fixed temperature $T_f$, baryon
number density $n_B$, and vanishing total strangeness. The constituents of this
gas are all hadron resonances up to a mass of 2 GeV; they are taken to decay
according to the experimentally observed branching ratios. The ratios of the
various resulting hadron production rates are tabulated as functions of $T_f$
and $n_B$. These tables can be used for the equilibration analysis of any heavy
ion data; we illustrate this for some specific cases.


title:
What $e^+e^-$ collider could make a ``no-lose'' search for MSSM Higgs
  bosons?

abstract:
  The lightest CP-even Higgs boson $h$ in the minimum supersymmetric standard
model (MSSM) has a mass upper bound depending on the top quark and squark
masses. An $e^+e^-$ collider with enough energy and luminosity to produce $h+Z$
at measurable rates up to the maximum $h$ mass would cover the entire MSSM
parameter space, if $h+A$ production was also searched for. We explore the
energy and/or luminosity needed for various top quark and squark masses. For
$m_t=150$\,GeV and 1\,TeV SUSY mass scale, a 230\,GeV collider with
10\,fb$^{-1}$ luminosity would suffice.


title: Nonet Symmetry and Two-Body Decays of Charmed Mesons

abstract:
  The decay of charmed mesons into pseudoscalar (P) and vector (V) mesons is
studied in the context of nonet symmetry. We have found that it is badly broken
in the PP channels and in the P sector of the PV channels as expected from the
non-ideal mixing of the \eta and the \eta'. In the VV channels, it is also
found that nonet symmetry does not describe the data well. We have found that
this discrepancy cannot be attributed entirely to SU(3) breaking at the usual
level of 20--30%. At least one, or both, of nonet and SU(3) symmetry must be
very badly broken. The possibility of resolving the problem in the future is
also discussed.


title: Majorons from Double Beta Decay

abstract: Wrong preprint number changed on previous version.


title: Semiclassical Gravity and Invisible Axions

abstract:
  We show that charged Eguchi-Hanson instantons provide a concrete and
calculable new source of intrinsic Peccei-Quinn symmetry breaking by quantum
gravity. The size of this breaking is shown to depend sensitively on the short
distance details of a given theory, but is generically suppressed by fermion
zero modes. Demanding that these gravitational effects not affet the axion
solution to the strong CP problem, we find that at least two sets of quarks
with differing Peccei-Quinn charges are required. In addition, these effects
obviate the cosmological axion domain wall problem but leave unchanged problems
associated with coherent axion oscillations.


title: Observable Majoron Emission in Neutrinoless Double Beta Decay

abstract:
  We consider a class of simplest Majoron models where neutrino- majoron
couplings can be in the range $g \sim 10^{-5}-10^{-3}$ leading to the
observability of neutrinoless double beta decay with majoron emission. The
majoron is a singlet of the electroweak gauge symmetry, thus avoiding conflict
with the LEP data on Z decay, which rules out the triplet and doublet majoron
models.


title: Multiple-Scattering Series For Color Transparency

abstract:
  Color transparency CT depends on the formation of a wavepacket of small
spatial extent. It is useful to interpret experimental searches for CT with a
multiple scattering scattering series based on wavepacket-nucleon scattering
instead of the standard one using nucleon-nucleon scattering. We develop
several new techniques which are valid for differing ranges of energy. These
techniques are applied to verify some early approximations; study new forms of
the wave-packet-nucleon interaction; examine effects of treating wave packets
of non-zero size; and predict the production of $N^*$'s in electron scattering
experiments.


title: Realistic Hadronic Matrix Element Approach to Color Transparency

abstract:
  Color transparency occurs if a small-sized wave packet, formed in a high
momentum transfer process, escapes the nucleus before expanding. The time
required for the expansion depends on the masses of the baryonic components of
the wave packet. Measured proton diffractive dissociation and electron deep
inelastic scattering cross sections are used to examine and severely constrain
the relevant masses. These constraints allow significant color transparency
effects to occur at experimentally accessible momentum transfers.


title: Collider discovery limits for supersymmetric Higgs bosons

abstract:
  The prospects for discovery of the five Higgs bosons of the minimal
supersymmetric standard model are assessed for existing and planned future
colliders, including LEP\,I, LEP\,II, LHC and SSC. As a benchmark for
comparisons, we take a top-quark mass $m_t= 150\,$GeV and squark mass parameter
$\tilde m= 1\,$TeV in evaluating one-loop radiative corrections; some results
for other $m_t$ values are also given. Searches based on the most promising
production and decay channels are taken into account. For large regions in
parameter space, detectable signals are predicted for one or more of the Higgs
bosons, but there remains a region for which no signals would be visible at the
above colliders.


title:
Implication of Combined Solar Neutrino Observation and their Theoretical
  Uncertainties

abstract:
  Constraints on the core temperature (T_c) of the Sun and on neutrino-
oscillation parameters are obtained from the existing solar neutrino data,
including the recent GALLEX and Kamiokande III results. (1) A purely
astrophysical solution to the solar neutrino problem is strongly disfavored by
the data: the best fit in a cooler Sun model requires an 8% reduction in T_c,
but the chi-sqaured test rejects this hypothesis at 99.99% C.L., suggesting new
neutrino physics. (2) Assuming the Standard Solar Model (SSM) and MSW
oscillations, the MSW parameters are constrained to two small regions: one in
the non-adiabatic region and the other in the large-mixing region. The
non-adiabatic solution gives a considerably better fit. For nu_e oscillations
into sterile neutrinos, the allowed region (90%) is constrained to non-
adiabatic oscillations. As long as the SSM is assumed, the neutrino mixing
angles are at least four times larger, or considerably smaller, than the
corresponding quark mixing angles. (3) Allowing both MSW oscillations and a
non-standard core temperature, a) the experiments determine the core
temperature at the 5% level, yielding a value consistent with the SSM
prediction. b) When T_c is used as a free parameter, the allowed MSW region is
broadened: a cooler Sun (T_c=0.95) allows mass and mixing implied by the SUSY
SO(10) GUT, while a warmer Sun (T_c=1.05) allows parameter space suggested by
intermediate-scale SO(10) GUTs. Superstring-inspired models are consistent with
all solutions. (4) From the narrowed parameter space, we predict the neutrino
spectral shape which should be observed in SNO. Throughout the calculation we
use the latest Bahcall-Pinsonneault SSM, and include nuclear and astrophysical
uncertainties in a simplified, but physically transparent way.


title:
Nonperturbative Corrections to Inclusive Beauty and Charm Decays: QCD
  versus Phenomenological Models

abstract:
  We present a selfconsistent method for treating nonperturbative effects in
inclusive nonleptonic and semileptonic decays of heavy flavour hadrons. These
effects give rise to powerlike corrections $\propto 1/m_Q^n\,$, $n \ge 2$ with
$m_Q$ denoting the heavy quark mass.The leading correction to the semileptonic
branching ratio occurs for n=2. It is expressed in terms of the
vector-pseudoscalar mass splitting: $\delta BR\ind{sl}/BR\ind{sl} \simeq
BR\ind{nl}\, \cdot \,6\,(\,(M_V^2-M_P^2)/m_Q^2)\cdot (c_+^2 - c_-^2)/2N_c$ and
yields a {\it reduction} of $BR\ind{sl}$. This nonperturbative correction
contributes to the nonleptonic width with a sign opposite to that of the
perturbative terms that are non-leading in $1/N_c$. In beauty decays the former
reduces the latter by 20 \% whereas in charm decays they more or less cancel.
This leads to a {\it reduction} of $BR\ind{sl}$ by no more than 10 \% in beauty
decays and by a factor of roughly two in charm decays. We confront these
results with those obtained from phenomenological models of heavy flavour
decays and find that such models are unable to mimic these leading corrections
by a specific choice of quark masses or by invoking Fermi motion.


title: Isospin Splitting in the Baryon Octet and Decuplet

abstract:
  Baryon mass splittings are analyzed in terms of a simple model with general
pairwise interactions. At present, the $\Delta$ masses are poorly known from
experiments. Improvement of these data would provide an opportunity to make a
significant test of our understanding of electromagnetic and quark-mass
contributions to hadronic masses. The problem of determining resonance masses
from scattering and production data is discussed.


title:
$V'Z$ and $V'W$ Production as Tests of Heavy Gauge Boson Couplings at
  Future Hadron Colliders

abstract:
  We point out that the production cross section of $pp\to V'V$, with
$V'=W',Z'$ and $V=W,Z$ is a useful diagnostic of $V'$ gauge couplings at future
hadron colliders. For $M_{Z'}\simeq1$ TeV it would allow determination of
combinations of $Z'$ gauge couplings to the quarks to around 10 percent. An
analysis of the extraction of gauge couplings from the complementary tests:
forward-backward asymmetry, rare decays $pp\to V'\to f_1{\bar f_2}V$, and the
production cross section $pp\to V'V$ is given in a model-independent framework.
Four ratios of charges are needed to characterize a general gauge theory with
an additional family-independent $U_1'$ factor. We show that there are four
functions of these ratios observable at hadron colliders, but for projected SSC
and LHC luminosities only two combinations can be extracted. These yield a
significant discrimination between interesting GUT-motivated models. Clean
tests of whether a new $W'$ couples to right-handed currents, of the ratio
$g_R/g_L$ of gauge couplings, and of the non-abelian vertex in left-right
symmetric models are described.


title: The Isgur-Wise Function in Small Velocity Limit

abstract:
  We discuss the Isgur-Wise function $\xi (y)$ in the small velocity (SV) limit
within the QCD sum rule method. The behavior of $\xi (y)$ in the SV limit is
sensitive to the particular form of the duality relations used to decontaminate
the sum rule predictions from the continuum contribution. Peculiarities of the
duality relations in the problem at hand are revealed. It is shown that the
proper requirements of duality and angular isotropy for S wave states lead to
an unambiguous form of the sum rules for the Isgur-Wise function. We illustrate
the constraints due to these requirements using a toy model of the harmonic
oscillator. The slope parameter and the shape of $\xi (y)$ are determined.


title: Some Simple Criteria for Gauged R-parity

abstract:
  We catalog some simple conditions which are sufficient to guarantee that
R-parity survives as an unbroken gauged discrete subgroup of the continuous
gauge symmetry in certain supersymmetric extensions of the standard model.


title: Troubles with the Minimal SU(5) Supergravity Model

abstract:
  We show that within the framework of the minimal $SU(5)$ supergravity model,
radiatively-induced electroweak symmetry breaking and presently available
experimental lower bounds on nucleon decay, impose severe constraints on the
available parameter space of the model which correspond to fine-tuning of the
model parameters of over two orders of magnitude. Furthermore, a
straightforward calculation of the cosmic relic density of neutralinos ($\chi$)
gives $\Omega_\chi h^2\gg1$ for most of the allowed parameter space in this
model, although small regions may still be cosmologically acceptable. We
finally discuss how the {\it no-scale flipped $SU(5)$ supergravity model}
avoids naturally the above troubles and thus constitutes a good candidate for
the low-energy effective supergravity model.


title:
KROWIG Version 1.0: Interfacing KRONOS and HERWIG or Higher Order
  Electromagnetic Radiative Corrections at HERA with Hadronic Final States

abstract:
  This manual describes version 1.0 of the Monte Carlo event generator KROWIG
for deep inelastic lepton hadron scattering at HERA. KROWIG combines the
implementation of QED radiative corrections in KRONOS with the QCD parton
showers and cluster fragmentation of HERWIG.


title: Sphaleron Erasure of Primordial Baryogenesis

abstract:
  If the present baryon-asymmetry is due to a Planck or GUT-scale matter
asymmetry then baryon- or lepton-number violating processes are constrained by
the condition that they do not subsequently erase this asymmetry. We present a
revision of the analysis of sphaleron baryon-number violating processes in the
standard model including lepton-mass effects. We find the surprising result
that a GUT-scale matter-asymmetry can survive the $B$ and $L$ violating
sphaleron interactions even though ($B- L$) is conserved and equals zero for
all temperatures. We extend the analysis to cover the minimal supersymmetric
standard model (MSSM) and also derive the constraints on the R-parity violating
couplings in extensions of the MSSM. In the case of the baryon number violating
dimension 4 operators we find, contrary to current wisdom, that the resulting
bounds can be avoided completely because of a residual lepton-flavour number
conservation; in the case of lepton number violating operators we find the
bounds are flavour dependent and can be avoided completely in definite flavour
channels. We also consider how the bounds are modified in the case there is a
Grand Unified extension of the supersymmetric model which introduces new lepton
flavour violating couplings.


title:
Two Photon Contribution to Polarization in $K^+ \rightarrow \pi^+ \mu^+
  \mu^-$

abstract:
  Short distance physics involving virtual top and charm quarks contributes to
$\mu^+$ (and $\mu^-$) polarization in the decay $K^+ \rightarrow \pi^+ \mu^+
\mu^-$. Measurement of the parity violating asymmetry $(\Gamma_R -
\Gamma_L)/(\Gamma_R + \Gamma_L)$, where $\Gamma_R$ and $\Gamma_L$ are the rates
to produce right and left-handed $\mu^+$, may provide valuable information on
the unitarity triangle. The parity violating asymmetry also gets a contribution
from Feynman diagrams with two photon intermediate states. We estimate this two
photon contribution to the asymmetry and discuss briefly the two photon
contribution to time reversal odd asymmetries that involve both the $\mu^+$ and
$\mu^-$ polarizations.


title: Heavy quark symmetry: ideas and applications

abstract:
  This report is a combined version of two talks presented by the authors at
the Edinburgh $b$-physics Workshop, December 1991. It presents the ideas of
heavy quark symmetry and gives an introduction to some applications. The
references indicate where to go for more information: they are not intended to
be complete, nor do they necessarily refer to the original work on any
particular subject.


title: On the Unmixed 17 keV Neutrino

abstract:
  Recently, it was suggested that the 17 keV neutrino does not mix with the
electron neutrino in the weak interactions. Instead, the $\beta$ decay mode
involving the 17 keV neutrino is induced by a completely new interaction,
presumably mediated by leptoquarks. A previous model for the ``unmixed 17 keV
neutrino" suffers from difficulties with experimental data and cosmological
constraints. Here we present an alternative model in which these difficulties
are resolved.


title:
Testing the Standard Model and Schemes for Quark Mass Matrices with CP
  Asymmetries in B Decays

abstract:
  The values of $\sin (2 \alpha)$ and $\sin (2 \beta)$, where $\alpha$ and
$\beta$ are angles of the unitarity triangle, will be readily measured in a B
factory (and maybe also in hadron colliders). We study the standard model
constraints in the $\sin (2 \alpha) - \sin (2 \beta)$ plane. We use the results
from recent analyses of $f_B$ and $\tau_b|V_{cb}|^2$ which take into account
heavy quark symmetry considerations. We find $\sin (2 \beta) \geq 0.15$ and
most likely $\sin (2 \beta) \roughly{>} 0.6$, and emphasize the strong
correlations between $\sin (2 \alpha)$ and $\sin (2 \beta)$. Various schemes
for quark mass matrices allow much smaller areas in the $\sin (2 \alpha) - \sin
(2 \beta)$ plane. We study the schemes of Fritzsch, of Dimopoulos, Hall and
Raby, and of Giudice, as well as the ``symmetric CKM'' idea, and show how CP
asymmetries in B decays will crucially test each of these schemes.


title: Technicolor Enhancement of $t \bar{t}$ Production at TeV-Colliders

abstract:
  It is shown that a technicolor theory containing a color-octet technipion,
usually denoted by $P^{0'}_{8}$, will give rise to an enhancement of $t \bar t$
production at the Tevatron, LHC and SSC, via the process $gg \rightarrow
P^{0'}_{8} \rightarrow t \bar t$. The relevant cross-sections are computed
taking into account the large lower bound on the top mass coming from the "top
search" experiments at LEP and CDF.
  At the LHC and SSC, the signal is found to be comparable to the QCD
background, making the process quite accesible.


title: The Electroweak Phase Transition in a Nonminimal Supersymmetric Model

abstract:
  We study the electroweak phase transition in a supersymmetric version of the
Standard Model, in which a gauge singlet superfield is added to the Higgs
sector. We show that the order of the transition is determined by the trilinear
soft supersymmetry breaking terms rather than by the $O ( m^{3} T )$ term in
the 1-loop, $T\neq0$ corrections. This fact removes the Standard Model upper
bound on the Higgs mass, $ m_{H} < 55 GeV$, coming from the requirement that
baryon asymmetry is not washed out by anomalous electroweak processes. We
perform a numerical analysis of parameter space including in the effective
potential top-stop contribution to 1-loop radiative corrections. We find that
this model is compatible with the preservation of baryon asymmetry for masses
of the lightest scalar up to about 170 GeV.


title: QCD Perturbation Theory at Low Energies

abstract:
  We apply the optimization procedure based on the Principle of Minimal
Sensitivity to the third-order calculation of $\R$. The effective couplant
remains finite, freezing to a value $\alpha_s/\pi = 0.26$ at low energies.
Using Poggio-Quinn-Weinberg smearing we find good agreement between theory and
experiment right down to zero energy.


title:
The Effects of Detector Descoping and Neutral Boson Mixing on New Gauge
  Boson Physics at the SSC

abstract:
  We examine how the abilities of an SDC-like detector to discover and identify
the origin of a new neutral gauge boson are affected by $Z_1-Z_2 $ mixing and
by variations in detector parameters such as lepton pair mass resolution,
particle identification efficiency, and rapidity coverage. Also examined is the
sensitivity of these results to variations in structure function uncertainties
and uncertainties in the machine integrated luminosity. Such considerations are
of importance when dealing with the issues of detector descoping and design.


title: Invariants Describing Quark Mixing and Mass Matrices

abstract:
  We introduce two new sets of invariant functions of quark mass matrices,
which express the constraints on these mass matrices due to knowledge of the
quark mixing matrix. These invariants provide a very simple method to test
candidate forms for mass matrices.


title: Discrete Symmetries from Broken $SU(N)$ and the MSSM

abstract:
  In order that discrete symmetries should not be violated by gravitational
effects, it is necessary to gauge them. In this paper we discuss the gauging of
$\Z_N$ from the breaking of a high energy $SU(N)$ gauge symmetry, and derive
consistency conditions for the resulting discrete symmetry fr om the
requirement of anomaly cancellation in the parent symmetry. These results are
then applied to a detailed analysis of the possible discrete symmetries
forbidding proton decay in the minimal supersymmetric standard model.


title:
QCD Corrections to Photon Production in Association with Hadrons in
  $e^+e^-$ Annihilation

abstract:
  A detailed investigation of the theoretical ambiguities present in the QCD
description of photon production in $e^+e^-$ annihilation is given. It is
pointed out that in a well-defined perturbative analysis it is necessary to
subtract the quark-photon collinear singularities. This subtraction requires
the introduction of an unphysical parameter in the perturbative part of the
cross section. The subtracted term is factored into non-perturbative
fragmentation function. The dependence on the unphysical parameter cancels in
the sum of non-perturbative and perturbative parts. It is pointed out that for
$E_{\gamma}\le \sqrt{s}/(2(1+\epsilon_c))$ the non-perturbative contributions
are suppressed. Using a general purpose next-to-leading order Monte Carlo
program, we calculate various physical quantities that were measured in LEP
experiments recently.


title:
The Rare Decays $\piee$, $\etaee$ and \etamumu$ in Chiral Perturbation
  Theory

abstract:
  We calculate the decay rates for $\piee$, $\etaee$ and $\etamumu$ in chiral
perturbation theory. The linear combination of counterterms necessary to render
these amplitudes finite is fixed by the recently measured branching fraction
for $\etamumu$. We find $\Br(\piee ) = 7\pm 1\times 10^{-8}$ and $\Br(\etaee
)=5\pm 1\times 10^{-9}$.


title: The Neutralino Relic Density in Minimal N=1 Supergravity

abstract:
  We compute the cosmic relic (dark matter) density of the lightest
supersymmetric particle (LSP) in the framework of minimal $N=1$ Supergravity
models with radiative breaking of the electroweak gauge symmetry. To this end,
we re--calculate the cross sections for all possible annihilation processes for
a general, mixed neutralino state with arbitrary mass. Our analysis includes
effects of all Yukawa couplings of third generation fermions, and allows for a
fairly general set of soft SUSY breaking parameters at the Planck scale. We
find that a cosmologically interesting relic density emerges naturally over
wide regions of parameter space. However, the requirement that relic
neutralinos do not overclose the universe does not lead to upper bounds on SUSY
breaking parameters that are strictly valid for all combinations of parameters
and of interest for existing or planned collider experiments; in particular,
gluino and squark masses in excess of 5 TeV cannot strictly be excluded. On the
other hand, in the ``generic'' case of a gaugino--like neutralino whose
annihilation cross sections are not ``accidentally'' enhanced by a nearby Higgs
or $Z$ pole, all sparticles should lie within the reach of the proposed $pp$
and $e^+e^-$ supercolliders. We also find that requiring the LSP to provide all
dark matter predicted by inflationary models imposes a strict lower bound of 40
GeV on the common scalar mass $m$ at the Planck scale, while the lightest
sleptons would have to be heavier


title: Meson Decay Constants from Isospin Mass Splittings in the Quark Model

abstract:
  Decay constants of $D$ and $B$ mesons are estimated within the framework of a
heavy-quark approach using measured isospin mass splittings in the $D$, $D^*$,
and $B$ states to isolate the electromagnetic hyperfine interaction between
quarks. The values $f_D = (262 \pm 29)$ MeV and $f_B = (160 \pm 17)$ MeV are
obtained. Only experimental errors are given; possible theoretical ambiguities,
and suggestions for reducing them, are noted.


title: The Rule of Discarding $1/N_c$ in Inclusive Weak Decays

abstract:
  We continue to investigate the effects of the (dominant) subleading operator
of the $\vec\sigma\vec H$ type in the $1/N_c$ parts of the weak nonleptonic
amplitudes. If the previous work concentrated on exclusive decays now we
analyse inclusive widths in a certain kinematic limit. Deviations from the
parton model predictions are found due to soft-gluon color exchange. In the
interference (i.e. $1/N_c$) terms they are stronger than in the
non-interference terms. The sign is negative so that the $1/N_c$ parts tend to
cancel. The absolute value of the effect is of order 1 in D-mesons and of order
0.50 in B mesons.


title: The prospects for CHORUS and NOMAD in the light of COBE and GALLEX

abstract:
  The most natural MSW neutrino oscillation interpretation of the GALLEX and
other solar neutrino data, which invokes $m_{\nu_\mu}\sim3\times10^{-3}\eV$,
and a general GUT see-saw hierarchy of neutrino masses,
$m_{\nu_{e,\mu,\tau}}\sim (m_{u,c,t})^2/M_U$, suggest that
$m_{\nu_\tau}\sim10\eV$ in agreement with the preference of COBE and other data
on large-scale structure in the Universe for a hot component in the Dark
Matter. The general see-saw model also suggests that neutrino mixing angles are
related to quark mixing angles, which is also consistent with the oscillation
interpretation of the solar neutrino data, and suggests that the forthcoming
CHORUS and NOMAD experiments at CERN have a good chance of observing $\nu_\mu -
\nu_\tau$ oscillations. We present a minimal realization of the general see-saw
hierarchy in the context of flipped $SU(5)$.


title:
Quark confinement , topological susceptibility and all that in 4
  dimensional gluodynamics

abstract:
  We discuss a few tightly connected problems, such as the $U(1)$ problem,
confinement, the $\theta$ -dependence within a framework of the dynamical toron
approach. We calculate two fundamental characteristics of the theory: the
vacuum expectation value (vev) of the Wilson loop and the topological
susceptibility. The analogy with well known 2+1 dimensional QED which exhibits
confinement phenomenon is also discussed.


title:
Contribution of Long Wavelength Gravitational Waves to the CMB
  Anisotropy

abstract:
  We present an in depth discussion of the production of gravitational waves
from an inflationary phase that could have occurred in the early universe,
giving derivations for the resulting spectrum and energy density. We also
consider the large-scale anisotropy in the cosmic microwave background
radiation coming from these waves. Assuming that the observed quadrupole
anisotropy comes mostly from gravitational waves (consistent with the
predictions of a flat spectrum of scalar density perturbations and the measured
dipole anisotropy) we describe in detail how to derive a value for the scale of
inflation of $(1.5-5)\times 10^{16}$GeV, which is at a particularly interesting
scale for particle physics. This upper limit corresponds to a 95\% confidence
level upper limit on the scale of inflation assuming only that the quadrupole
anisotropy from gravitational waves is not cancelled by another source. Direct
detection of gravitational waves produced by inflation near this scale will
have to wait for the next generation of detectors.


title: Squarks Below the Z

abstract:
  We investigate the possibility that the difference between the measurements
of $\alpha_3(M_Z)$ from the hadronic branching ratio of the $Z^0$ and the world
average of other measurements is due to the decay of the $Z^0$ into quark,
anti-squark, and gluino. Consequences for supersymmetry breaking models are
discussed.


title:
Autonomous Renormalization of the One-Loop Effective Potential and a 2
  Tev Higgs in SU(2)xU(1)

abstract:
  Branchina et al and Consoli have recently shown that the one-loop effective
potential (1LEP) of massless lambda-phi**4 theory can be renormalized in two
distinct ways. One of these is the conventional renormalization of Coleman and
Weinberg. The other requires an infinite wavefunction renormalization, and is
very similar to the "autonomous" renormalization of the Gaussian effective
potential. We apply the "autonomous" renormalization to the 1LEP of the SU(2)x
U(1) electroweak theory with zero bare Higgs mass. The predicted physical Higgs
mass is 1.9 TeV.


title: Are There Oscillations in the Baryon/Meson Ratio?

abstract:
  All available data indicate a surplus of baryon states over meson states for
energies greater than about 1.5 GeV. Since hadron-scale string theory suggests
that their numbers should become equal with increasing energy, it has recently
been proposed that there must exist exotic mesons with masses just above 1.7
GeV in order to fill the deficit. We demonstrate that a string-like picture is
actually consistent with the present numbers of baryon and meson states, and in
fact predicts regular oscillations in their ratio. This suggests a different
role for new hadronic states.


title: COBE, Inflation, and Light Scalars

abstract:
  Comparison of theobservedanisotropy with that predicted iadiabaticDM models
suggest that much of thserved signal may be due to long wavelenh gravitational
waves. In inflationary models this requires the generation of tensor
fluctuations to be at least comparable to scalar density fltuations. This i is
feasible, but depends sensitively on the inflaton potential. Alternatively,
isocurvature quantum fluctuations in an axion-like field could produce a
quadrupole anisotropy proportional to the gravitational wave anisotropy,k
independent of the inflaton potential. These could also produce large scale
structure with more power on larger scales than their adiabatic counterparts.


title:
COBE's Constraints on the Global Monopole and Texture Theories of Cosmic
  Structure Formation

abstract:
  We report on a calculation of large scale anisotropy in the cosmic microwave
background radiation in the global monopole and texture models for cosmic
structure formation. We have evolved the six component linear gravitational
field along with the monopole or texture scalar fields numerically in an
expanding universe and performed the Sachs-Wolfe integrals directly on the
calculated gravitational fields. On scales $> 7^\circ$, we find a Gaussian
distribution with an approximately scale invariant fluctuation spectrum. The
$\Delta T/T$ amplitude is a factor of 4-5 larger than the prediction of the
standard CDM model with the same Hubble constant and density fluctuation
normalization. The recently reported COBE-DMR results imply that global
monopole and texture models require high bias factors or a large Hubble
constant in contrast to standard CDM which requires very low $H_0$ and bias
values. For $H_0 = 70 {\rm {km\over sec} Mpc^{-1}}$, we find that normalizing
to the COBE results implies $b_8 \simeq 3.2\pm 1.4$ (95\% c.l.). If we restrict
ourselves to the range of bias factors thought to be reasonable before the
announcement of the COBE results, $1.5 \lsim b_8 \lsim 2.5$, then it is fair to
conclude that global monopoles and textures are consistent with the COBE
results and are a {\it better} fit than Standard CDM.


title:
Natural Inflation: Particle Physics Models, Power Law Spectra for Large
  Scale Structure, and Constraints from COBE

abstract:
  A pseudo-Nambu-Goldstone boson, with a potential of the form $V(\phi) =
\Lambda^4[1 \pm \cos(\phi/f)], naturally gives rise to inflation if $f \sim
M_{Pl}$ and $\Lambda \sim M_{GUT}$. We show how this can arise in
technicolor-like and superstring models, and work out an explicit string
example in the context of multiple gaugino condensation models. We study the
cosmology of this model in detail, and find that sufficient reheating to ensure
that baryogenesis can take place requires $f > 0.3 M_{Pl}$. The primordial
density fluctuation spectrum generated is a non-scale-invariant power law,
$P(k) \propto k^{n_s}$, with $n_s \simeq 1 - (M^2_{Pl}/8\pi f^2)$, leading to
more power on large length scales than the $n_s = 1$ Harrison-Zeldovich
spectrum. The standard CDM model with $0 \la n_s \la 0.6-0.7$ could in
principle explain the large-scale clustering observed in the APM and IRAS
galaxy surveys as well as large-scale flows, but the COBE microwave anisotropy
implies such low amplitudes (or high bias factors, $b>2$) for these CDM models
that galaxy formation occurs too late to be viable; combining COBE with
sufficiently early galaxy formation or the large-scale flows leads to $n_s
>0.6$, or $f > 0.3 M_{Pl}$ as well. For extended and power law inflation
models, this constraint is even tighter, $n_s > 0.7$; combined with other
bounds on large bubbles in extended inflation, this leaves little room for most
extended models.


title: Phase Structure of QED3 at Finite Temperature

abstract:
  Dynamical symmetry breaking in three-dimensional QED with N fermion flavours
is considered at finite temperature, in the large $N$ approximation. Using an
approximate treatment of the Schwinger-Dyson equation for the fermion
self-energy, we find that chiral symmetry is restored above a certain critical
temperature which depends itself on $N$. We find that the ratio of the
zero-momentum zero-temperature fermion mass to the critical temperature has a
large value compared with four-fermion theories, as had been suggested in a
previous work with a momentum-independent self-energy. Evidence of a
temperature- dependent critical $N$ is shown to appear in this approximation.
The phase diagram for spontaneous mass generation in the theory is presented in
$T-N$ space.


title: Inflation and Large Scale Structure Formation After COBE

abstract:
  The simplest realizations of the new inflationary scenario typically give
rise to primordial density fluctuations which deviate logarithmically from the
scale free Harrison - Zeldovich spectrum. We consider a number of such examples
and, in each case we normalize the amplitude of the fluctuations with the
recent COBE measurement of the microwave background anisotropy. The predictions
for the bulk velocities as well as anisotropies on smaller (~1-2 degrees)
angular scales are compared with the Harrison-Zeldovich case. Deviations from
the latter range from a few to about 15 percent. We also estimate the redshift
beyond which the quasars would not be expected to be seen. The inflationary
quasar cutoff redshifts can vary by as much as 25\% from the Harrison-Zeldovich
case. We find that the inflationary scenario provides a good starting point for
a theory of large scale structure in the universe provided the dark matter is a
combination of cold plus (~10-30 \%) hot components.


title: Flavour Democracy Calls for the Fourth Generation

abstract:
  It is argued with the help of an illustrative model, that the inter--species
hierarchy among the fermion masses and the quark mixing angles can be
accommodated naturally in the standard model with (approximate) flavor
democracy provided there are four families of sequential quark--leptons with
all members of the fourth family having roughly equal masses. The special
problem of light neutrino masses (if any) and possible solutions are also
discussed.


title: Electroweak Corrections in Technicolor Reconsidered

abstract:
  Radiative corrections to electroweak parameters in technicolor theories may
be evaluated by one of two techniques: either one estimates spectral function
integrals using scaled QCD data, or one uses naive dimensional analysis with a
chiral Lagrangian. The former yields corrections to electroweak parameters
proportional to the number of flavors and the number of colors, while the
latter is proportional to the number of flavors squared and is independent of
the number of colors. We attempt to resolve this apparent contradiction by
showing that the spectrum of technicolor one obtains by scaling QCD data to
high energies is unlikely to resemble that of an actual technicolor theory. The
resonances are likely to be much lighter than naively supposed and the
radiative corrections to electroweak parameters may by much larger. We also
argue that much less is known about the spectrum and the radiative corrections
in technicolor than was previously believed.


title:
Once more on $\theta$-vacua in $2+1$ dimensional QED and 3+1 dimensional
  gluodynamics

abstract:
  Two different but tightly connected problems, $U(1)$ and strong CP violation
problems, are discussed in two different models which exhibit both asymptotic
freedom and confinement. One of them is the 3d Polyakov's model of compact QED
and the other is 4d gluodynamics. It is shown that although both these models
possess the long range interactions of the topological charges, only in the
former case physics does not depend on $\theta$; while the latter exhibits an
explicit $\theta$- dependence. The crucial difference is due to the
observation, that the pseudoparticles of 4d gluodynamics possess an aditional
quantum number, apart of the topological charge $Q$ .


title: I=3/2 $K \pi$ Scattering in the Nonrelativisitic Quark Potential Model

abstract:
  We study $I=3/2$ elastic $K\pi $ scattering to Born order using
nonrelativistic quark wavefunctions in a constituent-exchange model. This
channel is ideal for the study of nonresonant meson-meson scattering amplitudes
since s-channel resonances do not contribute significantly. Standard quark
model parameters yield good agreement with the measured S- and P-wave phase
shifts and with PCAC calculations of the scattering length. The P-wave phase
shift is especially interesting because it is nonzero solely due to $SU(3)_f$
symmetry breaking effects, and is found to be in good agreement with experiment
given conventional values for the strange and nonstrange constituent quark
masses.


title:
Renormalization Group Improvement of the Effective Potential in Massive
  O(N) Symmetric $\phi^4$ Theory

abstract:
  The renormalization group is used to improve the effective potential of
massive ${\rm O}(N)$ symmetric $\phi^4$ theory. Explicit results are given at
the two-loop level.


title:
New Constraints on Neutralino Dark Matter in the Supersymmetric Standard
  Model

abstract:
  We investigate the prospects for neutralino dark matter within the
Supersymmetric Standard Model (SSM) including the constraints from universal
soft supersymmetry breaking and radiative breaking of the electroweak symmetry.
The latter is enforced by using the one-loop Higgs effective potential which
automatically gives the one-loop corrected Higgs boson masses. We perform an
exhaustive search of the allowed five-dimensional parameter space and find that
the neutralino relic abundance $\Omega_\chi h^2_0$ depends most strongly on the
ratio $\xi_0\equiv m_0/m_{1/2}$. For $\xi_0\gg1$ the relic abundance is almost
always much too large, whereas for $\xi_0\ll1$ the opposite occurs. For
$\xi_0\sim1$ there are wide ranges of the remaining parameters for which
$\Omega_\chi\sim1$. We also determine that $m_{\tilde q}\gsim250\GeV$ and
$m_{\tilde l}\gsim100\GeV$ are necessary in order to possibly achieve
$\Omega_\chi\sim1$. These lower bounds are much weaker than the corresponding
ones derived previously when radiative breaking was {\it not} enforced.


title: Supersymmetry and Tau Decay

abstract:
  The impact of the new tau decay data on the various $\tau$ puzzles and on the
possibility of approximate supersymmetry is discussed. The most economical
solution of the problems in $\tau$ decay and that favored by recent new data
supports the existence of gluinos below one GeV.


title: Large Scale Structure by Global Monopoles and Cold Dark Matter

abstract:
  A cosmological model in which the primordial perturbations are provided by
global monopoles and in which the dark matter is cold has several interesting
features. The model is normalized by choosing its single parameter within the
bounds obtained from gravitational wave constraints and by demanding coherent
velocity f1ows of about 600km/sec on scales of $50 h^{-1} Mpc$. Using this
normalization, the model predicts the existence of dominant structures with
mass $2\times 10^{16} M_\odot$ on a scale $35 h^{-1}Mpc$ i.e. larger than the
horizon at $t_{eq}$. The magnitude of the predicted mass function in the
galactic mass range is in good agreement with the observed Schechter function.


title: Nontopological Global Field Dynamics

abstract:
  We use arguments based on Derrick's theorem to show that the property of
collapse which is the key feature of global texture appears in several field
theory models with broken global O(N) symmetry. Such models do not necessarily
have nontrivial third homotopy group of the vacuum manifold but may give rise
to collapsing global field configurations with properties similar to textures.
It is verified that configurations with planar and cylindrical geometries do
not collapse. The existence of critical parameters for collapse of spherically
symmetric global field configurations is verified both analytically and
numerically.


title: Long-Wavelength Oscillations and the Gallex Solar Neutrino Signal

abstract:
  The recently reported solar neutrino signal in the $^{71}$Ga GALLEX detector
adds a new dimension to the solar neutrino puzzle, complementing the previously
known signals in $^{37}$Cl and water-Cherenkov detectors. Possible explanations
for this new signal in terms of matter-enhanced neutrino oscillations (MSW
effect) are already awaiting in the literature. We point out here that
long-wavelength vacuum oscillations can furnish an alternative explanation of
all three signals simultaneously; such solutions give neutrino spectra with
distinctive energy dependence and seasonal time dependence. %This is a Revtex
file, which is Latex-based but depends upon inputting the %Revtex style files
distributed by APS/Physical Review. For more information, %contact Peggy
Sutherland at MIS@APSEDOFF.BITNET, phone (516) 349-7800 ext 674


title: LEP1 vs. Future Colliders: Effective Operators And Extended Gauge Group

abstract:
  In an effective Lagrangian approach to physics beyond the Standard Model, it
has been argued that imposing $SU(2) \times U(1)$ invariance severely restricts
the discovery potential of future colliders. We exhibit a possible way out in
an extended gauge group context.


title: Spin Structure Functions

abstract:
  I review the spin dependent structure functions which control dominant
(twist-2) and sub-dominant (twist-3) phenomena in hard processes. Novel effects
associated with chirally odd parton distributions and with transverse
polarization are emphasized.


title: Color Confinement, Abelian Gauge and Renormalization Group Flow

abstract:
  Under the assumption that the color charge can be written in a BRST exact
form, the color confinement mechanism proposed by Kugo and Ojima (KO) explains
the confinement of any colored particles including dynamical quarks and gluons.
This mechanism, however, is known to break down in the Abelian gauge which
treats the maximal Abelian subgroup of the gauge group in a special manner. In
order to study whether the failure of the KO mechanism is particular only to
the Abelian gauge or whether this failure occurs in a wide class of gauges
including the ordinary Lorentz type gauge, we carry out a renormalization group
study of the $SU(2)$ gauge theory in the gauge fixing space. Our gauge fixing
space consists of four distinct regions that are not connected with each other
by renormalization group flows, and we find that the Abelian gauge is {\it
infrared unstable} in three regions which include the Lorentz type gauge. This
suggests that the failure of the KO mechanism is a phenomenon which occurs only
in the Abelian gauge. We also find that the Lorentz gauge is infrared stable.


title: Indirect detection of unstable heavy dark matter

abstract:
  Unstable relics with lifetime longer than the age of the Universe could be
the dark matter today. Electrons, photons and neutrinos are a natural outcome
of their decay and could be searched for in cosmic rays and in $\gamma$-ray and
neutrino detectors. I compare the sensitivities of these three types of
searches to the mass and lifetime of a generic unstable particle. I show that
if the relics constitute our galactic halo and their branching ratios into
electron-positrons, photons and neutrinos are comparable, neutrino searches
would probe the longest lifetimes for masses $\simge 40 \TeV$, while
electron-positron searches would be better but more uncertain for lighter
particles. If instead the relics are not clustered in our halo, neutrinos are
more sensitive a probe than $\gamma$-rays for masses $\simge 700 \GeV$. A $ 1
\sqkm $ neutrino telescope should be able to explore lifetimes up to $ \sim
10^{30} \sec $ while searching for neutrinos from unstable particles above the
atmospheric background.


title: Comment on $\tau$ decay puzzle

abstract:
  We analize the current data on $\tau$-lepton decays and show that they are
consistent with the Standard Model


title: Three generations mixing and the $\tau$ decay puzzle

abstract:
  We consider the possibility that the $\tau$ decay puzzle, if it is confirmed
in future experiments, is a consequence of the Kobayashi-Maskawa mixing in the
leptonic sector


title: Leptons masses in an $SU(3)_L\otimes U(1)_N$ Gauge Model

abstract:
  The $SU(3)_c\otimes SU(3)_L\otimes U(1)_N$ model of Pisano and Pleitez
extends the Standard Model in a particularly nice way, so that for example the
anomalies cancel only when the number of generations is divisible by three. The
original version of the model has some problems accounting for the lepton
masses. We resolve this problem by modifying the details of the symmetry
breaking sector in the model.


title: Hard Scattering in QCD with Polarized Beams

abstract:
  I show that factorization for hard processes in QCD is also valid when the
detected particles are polarized, and that the proof of the theorem determines
the operator form for the parton densities. Particular attention is given to
the case of transversely polarized incoming hadrons.


title:
Navigating Around the Algebraic Jungle of QCD: Efficient Evaluation of
  Loop Helicity Amplitudes

abstract:
  A method is developed whereby spinor helicity techniques can be used to
simplify the calculation of loop amplitudes. This is achieved by using the
Feynman-parameter representation where the offending off-shell loop momenta do
not appear. Background Feynman gauge also helps to simplify the calculations.
This method is applicable to any Feynman diagram with any number of loops as
long as the external masses can be ignored, and it is at least as efficient as
the string technique in the special circumstances when the latter can be used.
In order to minimize the very considerable algebra encountered in non-abelian
gauge theories, graphical methods are developed for most of the calculations.
This enables the large number of terms encountered to be organized visually in
the Feynman diagram without the necessity of having to write down any of them
algebraically. A one-loop four-gluon amplitude in a particular helicity
configuration is computed explicity to illustrate the method.


title:
Constraints from Global Symmetries on Radiative Corrections to the Higgs
  Sector

abstract:
  We discuss the implications of global symmetries on the radiative corrections
to the Higgs sector. We focus on two examples: the charged Higgs mass in the
minimal supersymmetric model and the Higgs couplings to vector boson pairs. In
the first case, we find that in the absence of squark mixing a global
SU(2)$\times$SU(2) symmetry protects the charged Higgs mass from corrections of
${\cal O}(g^2m^4_t/m^2_W)$. In the second case, it is the {\it custodial}
symmetry which plays an analogous role in constraining the fermion-mass
dependence of the radiative corrections.


title: Testing Quantum Mechanics in the Neutral Kaon System

abstract:
  The neutral kaon system is a sensitive probe of quantum mechanics. We revive
a parametrization of non-quantum-mechanical effects that is motivated by
considerations of the nature of space-time foam, and show how it can be
constrained by new measurements of $K_L \rightarrow 2\pi$ and $K_{L,S}$
semileptonic decays at LEAR or a $\phi$ factory.


title:
New Higgs Signatures in Supersymmetry with Spontraneously Broken R
  Parity"

abstract:
  Higgs production from $Z$ decay in supersymmetry with spontaneous broken R
parity proceeds mostly by the Bjorken process as in the standard model.
However, the corresponding production rates can be weaker than in the standard
model (SM), especially in the low mass region. This will substantially weaken
the Higgs boson mass limits derived from LEP1. More strikingly, the main Higgs
decay channel is "invisible", over most of the mass range accessible to LEP1,
leading to events with large missing energy carried by majorons. This
possibility should be taken into account in the planning of Higgs boson search
strategies not only at LEP but also at high energy supercolliders.


title: Recent Developments in the Theory of Heavy-Quark Decays

abstract:
  I report on recent developments in the heavy-quark effective theory and its
application to $B$ meson decays. The parameters of the effective theory, the
spin-flavor symmetry limit, and the leading symmetry-breaking corrections to it
are discussed. The results of a QCD sum rule analysis of the universal
Isgur-Wise functions that appear at leading and subleading order in the $1/m_Q$
expansion are presented. I illustrate the phenomenological applications of this
formalism by focusing on two specific examples: the determination of $V_{cb}$
from the endpoint spectrum in semileptonic decays, and the study of
spin-symmetry violating effects in ratios of form factors. I also briefly
comment on nonleptonic decays.


title:
Final-State-Interaction Simulation of T-Violation in the Top-Quark
  Semileptonic Decay

abstract:
  The standard electroweak final-state interaction induces a false T-odd
correlation in the top-quark semileptonic decay. The correlation parameter is
calculated in the standard model and found to be considerably larger than those
that could be produced by genuine T-violation effects in a large class of
theoretical models.


title: Vector Meson Dominance and Free Quarks

abstract:
  We study the electromagnetic pion form factor and the VV - AA two point
function for momenta -(600 MeV)^2 < q^2 < (600 MeV)^2 and we note the
similarity between vector meson dominance and two versions of the free
constituent quark model. The similarity is more striking when the momentum
dependence of the quark mass is taken into account. We consider the
implications for QCD and other theories.


title: Oblique Corrections in Technicolor with a Scalar

abstract:
  We study a model in which the electroweak symmetry is dynamically broken by
technicolor interactions and the symmetry-breaking is communicated to the
quarks and leptons by a weak doublet of scalar fields. The scalars may be
regarded as elementary or as light bound states arising from strong extended
technicolor interactions. This model is unusual in that it can provide a heavy
top quark without generating large flavor-changing neutral currents. Our work
focuses on the model's phenomenology, particularly the oblique electroweak
radiative corrections. We demonstrate that while oblique corrections and FCNC
effects limit the allowed parameter space, the model remains viable. In
particular, if the scalar is relatively heavy, the model can accommodate a wide
range of top quark masses.


title: The Nucleon ``Tensor Charges'' and the Skyrme Model

abstract:
  The lowest moment of the twist-two, chiral-odd parton distribution $h_1(x)$
of the nucleon can be related to the so-called ``tensor charges'' of the
nucleon. We consider the tensor charges in the Skyrme model, and find that in
the large-$N_c$, SU(3)-symmetric limit, the model predicts that the octet
isosinglet tensor charge, $g^8_T$, is of order $1/N_c$ with respect to the
octet isovector tensor charge, $g^3_T$. The predicted $F/D$ ratio is then 1/3,
in the large-$N_c$ limit. These predictions coincide with the Skyrme model
predictions for the octet ${\it axial}$ charges, $g^8_A$ and $g^3_A$. (The
prediction $F/D=1/3$ for the axial charges differs from the commonly quoted
prediction of 5/9, which is based on an inconsistent treatment of the
large-$N_c$ limit.) The model also predicts that the singlet tensor charge,
$g^0_T$, is of order $1/N_c$ with respect to $g^3_T$.


title: Test of an Equivalence Theorem at One-Loop

abstract:
  We show that the equivalence theorem approximating one-loop gauge sector
diagrams by including only Goldstone bosons in the loop gives a remarkably poor
approximation to the amplitude for the decay $H\rightarrow \gamma \gamma $ and
for the process $\gamma \gamma \rightarrow HH$. At one loop, large logarithms
can arise that evade power counting arguments.


title: Gaussian Effective Potential for the U(1) Higgs Model

abstract:
  In order to investigate the Higgs mechanism nonperturbatively, we compute the
Gaussian effective potential (GEP) of the U(1) Higgs model ("scalar
electrodynamics"). We show that the same simple result is obtained in three
different formalisms. A general covariant gauge is used, with Landau gauge
proving to be optimal. The renormalization generalizes the "autonomous"
renormalization for lambda-phi^4 theory and requires a particular relationship
between the bare gauge coupling e_B and the bare scalar self- coupling
lambda_B. When both couplings are small, then lambda is proportional to e^4 and
the scalar/vector mass-squared ratio is of order e^2, as in the classic 1-loop
analysis of Coleman and Weinberg. However, as lambda increases, e reaches a
maximum value and then decreases, and in this "nonperturbative" regime the
Higgs scalar can be much heavier than the vector boson. We compare our results
to the autonomously renormalized 1-loop effective potential, finding many
similarities. The main phenomenological implication is a Higgs mass of about 2
TeV.


title:
Production of Three Vector Bosons in e+e- Annihilation as a Test of W+-,
  Z, gamma Self-Interactions

abstract:
  We study the vector-boson production processes e+e- --> WWZ and e+e-
-->WWgamma which are directly affected by the trilinear and quadrilinear self
couplings of the W, Z and gamma. Our analysis is based upon a single-parameter
effective-Lagrangian model for these self interactions which contains the
standard model as a special case. Consequences for the phenomenology at an e+e-
collider of 500 GeV (NLC) are discussed, and fits of the free parameter around
its standard model value are carried out.


title: Generalized Dimensional Analysis

abstract:
  I describe a version of so-called naive dimensional analysis, a rule for
estimating the sizes of terms in an effective theory below the scale of chiral
symmetry breaking induced by a strong gauge interaction. The rule is simpler
and more general than the original, which it includes as a special case. I also
give a simple qualitative interpretation of the rule.


title: Nucleon Decay in the Minimal Supersymmetric $SU(5)$ Grand Unification

abstract:
  We make a detailed analysis on the nucleon decay in the minimal
supersymmetric $SU(5)$ grand unified model. We find that a requirement of the
unification of three gauge coupling constants leads to a constraint on a mass
$M_{H_C}$ of color-triplet Higgs multiplet as $2 \times 10^{13}~\GeV \leq
M_{H_C} \leq 2 \times 10^{17}~\GeV$, taking both weak- and GUT-scale threshold
effects into account. Contrary to the results in the previous analyses, the
present experimental limits on the nucleon decay turn out to be consistent with
the SUSY particles lighter than 1~TeV even without a cancellation between
matrix elements contributed from different generations, if one adopts a
relatively large value of $M_{H_C}$ ($\ge2\times 10^{16}~\GeV$). We also show
that the Yukawa coupling constant of color-triplet Higgs multiplet does not
necessarily blow up below the gravitational scale ($2.4\times10^{18}~\GeV$)
even with the largest possible value of $M_{H_C}$. We point out that the
no-scale model is still viable, though it is strongly constrained.


title: Current correlators to all orders in the quark masses

abstract:
  The contributions to the coefficient functions of the quark and the mixed
quark-gluon condensate to mesonic correlators are calculated for the first time
to all orders in the quark masses, and to lowest order in the strong coupling
constant. Existing results on the coefficient functions of the unit operator
and the gluon condensate are reviewed. The proper factorization of short- and
long-distance contributions in the operator product expansion is discussed in
detail. It is found that to accomplish this task rigorously the operator
product expansion has to be performed in terms of non-normal-ordered
condensates. The resulting coefficient functions are improved with the help of
the renormalization group. The scale invariant combination of dimension 5
operators, including mixing with the mass operator, which is needed for the
renormalization group improvement, is calculated in the leading order.


title: Instability and Subsequent Evolution of Electroweak Bubbles

abstract:
  Bubbles in a first-order electroweak phase transition are nucleated with
radii $R_0$ and expand with velocity $v$. If $v$ is subsonic, a bubble becomes
unstable to non-spherical perturbations when its radius is roughly $10^4\,
R_0$. These perturbations accelerate the transition, and the effective velocity
of bubble growth rapidly becomes supersonic. The transition should subsequently
proceed spherically via detonation. If for some reason the onset of detonation
is postponed, the surface area of the bubbles may be enhanced by $10^5$. We
discuss consequences for electroweak baryogenesis.


title:
Topological phase due to electric dipole moment and magnetic monopole
  interaction

abstract:
  We show that there is an anologous Aharonov-Casher effect on a neutral
particle with electric dipole moment interacting with a magnetic filed produced
by magnetic monopoles.


title: Semileptonic Kaon Decays in Chiral Perturbation Theory

abstract:
  We present the matrix elements for the semileptonic kaon decays
$K_{l2\gamma}$, $K_{l2l^+l^-}$, $K_{l2l'^+l'^-}$, $K_{l3}$, $K_{l3\gamma}$ and
$K_{l4}$ at next-to-leading order in chiral perturbation theory and compare the
predictions with experimental data. Monte Carlo event generators are used to
calculate the corresponding rates at DAFNE. We discuss the possibilities to
improve our knowledge of the low-energy structure of the Standard Model at this
and similar machines.


title: Spontaneous CP violation in Supersymmetric theories

abstract:
  We study the minimal version of the supersymmetric standard model with
spontaneous CP breaking. In this model, the KM matrix is real and contributions
to $\varepsilon$ arise from box diagrams involving squarks. We analyze the
region of the parameter space which corresponds to values for $\varepsilon$,
$\varepsilon^\prime/\varepsilon$ and the neutron electric dipole moment (NEDM)
in agreement with the experimental data. We show that the CP violating phases
must be of $\calo (10^{-2})$ and the NEDM lies near its present experimental
limit.


title:
Photon production through $A_1$ resonance in high energy heavy ion
  collisions

abstract:
  Electromagnetic radiation from excited hadronic matter is one of the best
ways to study the properties of the matter.
  Considering various processes in the hadronic gas, Kapusta et al
\cite{Kapusta_photons} have found a $\pi\rho \rightarrow \pi\gamma$ reaction
with intermediate virtual pion or rho to be the main source of photons with
energy greater than 0.7 GeV.
  However, at temperatures considered T=100-200 MeV, a $\pi\rho$ pair can
easily form an $A_1$(1260) resonance, and we show that this mechanism leads to
the photon production rates exceeding those suggested previously. The paper is
in LATEX, figures available from authors.


title: Radiative Rare B Decays into Higher K-Resonances

abstract:
  We estimate the contributions of higher K-resonances to the radiative rare
decays b -> s gamma. We use the spin symmetry for heavy quarks to reduce the
number of independent form factors to four Isgur-Wise functions, which are
estimated from the wave function model of Isgur, Scora, Grinstein, and Wise.
Our results suggest a substantially larger branching fraction for the decay B
-> K*2(1430) gamma than previous investigations.


title: Can Polarised Drell-Yan Shed More Light On The Proton Spin?

abstract:
  We analyse polarised Drell-Yan process using the factorisation method and
derive operator definitions for polarised parton distribution functions. We
demonstrate that a factorisation analogous to that in the unpolarised Drell-Yan
case holds in this process. We study the leading order gluonic contribution to
the first moment of polarised Drell-Yan function and show that it is consistent
with results obtained from polarised deep inelastic scattering.


title: Breakdown of Dimensional Regularization in the Sudakov Problem

abstract:
  An explicit example is presented (a one-loop triangle graph) where
dimensional regularization fails to regulate the infra-red singularities that
emerge at intermediate steps of studying large-$Q^2$ Sudakov factorization. The
mathematical nature of the phenomenon is explained within the framework of the
theory of the $As$-operation.


title: Gauge Model of Generation Nonuniversality Reexamined

abstract:
  A gauge model of generation nonuniversality proposed in 1981 is reexamined in
the light of present precision electroweak measurements. Two necessary features
of this model are that the tau lifetime should be longer than predicted by the
standard model and that the rho parameter measured at the Z peak should have an
additional negative contribution. Both trends are noticeable in present data. A
future decisive test of this model would be the discovery of new W and Z bosons
with nearly degenerate masses of a few TeV.


title: Soft dilepton production in relativistic heavy ion collisions

abstract:
  Production of electron-positron pairs with invariant masses less than 300 MeV
from thermalized hadronic matter in relativistic heavy ion collisions is
calculated using a soft virtual photon approximation. The general theoretical
framework is reviewed and extended to include arbitrarily massed and charged
reaction partners, which we apply to pions and quarks. This result, exact
within the soft photon approximation, is compared with a widely used
approximate result which uses an electromagnetic amplitude limited in validity
to momentum transfers less than $4m_{\pi(q)}^{2}$. A comparison is made between
the rate of production of zero total momentum soft dileptons obtained using
resummation techniques in QCD perturbation theory to that which we calculate
using this soft photon approximation.


title: Black Holes from Nucleating Strings

abstract:
  We evaluate the probability that a loop of string that has spontaneously
nucleated during inflation will form a black hole upon collapse, after the end
of inflation. We then use the observational bounds on the density of primordial
black holes to put constraints on the parameters of the model. Other
constraints from the distortions of the microwave background and emission of
gravitational radiation by the loops are considered. Also, observational
constraints on domain wall nucleation and monopole pair production during
inflation are briefly discussed.


title:
Fragmentation of Transversely Polarized Quarks Probed in Transverse
  Momentum Distributions

abstract:
  It is shown that the azimuthal dependence of the distribution of hadrons in a
quark jet is a probe of the transverse spin of the quark initiating the jet.
This results in a new spin-dependent fragmentation function that acts at the
twist-2 level. One example of a process where it contributes is semi-inclusive
deeply inelastic scattering with a transversely polarized nucleon target but
with an {\em unpolarized} electron beam. This process is treated in detail.
Another process is the cross section for singly polarized hadron-hadron
scattering when two high $p_{\perp}$ hadrons are measured in the final state
and are close to back-to-back in azimuth. The new fragmentation function is
sensitive to the coupling of the fragmentation process to (spontaneous) chiral
symmetry breaking.


title:
The gravitational wave contribution to CMB anisotropies and the
  amplitude of mass fluctuations from COBE results

abstract:
  A stochastic background of primordial gravitational waves may substantially
contribute, via the Sachs--Wolfe effect, to the large--scale Cosmic Microwave
Background (CMB) anisotropies recently detected by COBE. This implies a {\it
bias} in any resulting determination of the primordial amplitude of density
fluctuations. We consider the constraints imposed on $n<1$ (``tilted")
power--law fluctuation spectra, taking into account the contribution from both
scalar and tensor waves, as predicted by power--law inflation. The
gravitational--wave contribution to CMB anisotropies generally reduces the
required {\it rms} level of mass fluctuation, thereby increasing the linear
{\it bias parameter}, even in models where the spectral index is close to the
Harrison--Zel'dovich value $n=1$. This ``gravitational--wave bias" helps to
reconcile the predictions of CDM models with observations on pairwise galaxy
velocity dispersion on small scales.