title:
The one-loop renormalization of the MSSM Higgs sector and its
  application to the neutral scalar Higgs masses

abstract:
  The structure of the Higgs sector in the minimal supersymmetric standard
model is reviewed at the one-loop level. An on-shell renormalization scheme of
the MSSM Higgs sector is presented in detail together with the complete list of
formulae for the neutral Higgs masses at the one-loop level. The results of a
complete one- loop calculation for the mass spectrum of the neutral MSSM Higgs
bosons and the quality of simpler Born-like approximations are discussed for
sfermion and gaugino masses in the range of the electroweak scale.


title:
The Anomalous Magnetic Moments of the Electron and the Muon - Improved
  QED Predictions Using Pade Approximants

abstract:
  We use Pade Approximants to obtain improved predictions for the anomalous
magnetic moments of the electron and the muon. These are needed because of the
very precise experimental values presently obtained for the electron, and soon
to be obtained at BNL for the muon. The Pade prediction for the QED
contribution to the anomalous magnetic moment of the muon differs significantly
from the naive perturbative prediction.


title:
A Gauge Invariant Electromagnetic Two-Point Function For Heavy Light
  Quark Systems

abstract:
  A gauge invariant electromagnetic two-point function, crucial to the
investigations of the violation of isospin symmetry, is derived for heavy-light
quark systems. Thus QED can be consistently introduced into the QCD Sum Rule
method, which was not previously possible.


title: Heavy Meson Form Factors, Couplings and Exclusive Decays in QCD

abstract:
  We discuss the form factors of the heavy-to-light transitions $B \ra \pi$ and
$D\ra \pi$, the $B^*B \pi$ and $D^*D \pi$ coupling constants, and the
nonfactorizable amplitude of the decay $ B \ra J/\psi K$ in the framework of
QCD sum rules.


title: Probing New Physics in Rare Charm Processes

abstract:
  The possibility of using the charm system to search for new physics is
addressed. Phenomena such as $D^0-\bar D^0$ mixing and rare decays of charmed
mesons are first examined in the Standard Model to test our present
understanding and to serve as benchmarks for signals from new sources. The
effects of new physics from various classes of non-standard dynamical models on
$D^0-\bar D^0$ mixing are investigated.


title: Novel Approach to Confront Electroweak Data and Theory

abstract:
  A novel approach to study electroweak physics at one-loop level in generic
${\rm SU(2)_L \times U(1)_Y}$ theories is introduced. It separates the 1-loop
corrections into two pieces: process specific ones from vertex and box
contributions, and universal ones from contributions to the gauge boson
propagators. The latter are parametrized in terms of four effective form
factors $\bar{e}^2(q^2)$, $\bar{s}^2(q^2)$, $\bar{g}_Z^2(q^2)$ and $\bar{g}_W^2
(q^2)$ corresponding to the $\gamma\gamma$, $\gamma Z$, $ZZ$ and $WW$
propagators. Under the assumption that only the Standard Model contributes to
the process specific corrections, the magnitudes of the four form factors are
determined at $q^2=0$ and at $q^2=\mmz$ by fitting to all available precision
experiments. These values are then compared systematically with predictions of
${\rm SU(2)_L \times U(1)_Y}$ theories. In all fits $\alpha_s(\mz)$ and
$\bar{\alpha}(\mmz)$ are treated as external parameters in order to keep the
interpretation as flexible as possible. The treatment of the electroweak data
is presented in detail together with the relevant theoretical formulae used to
interpret the data. No deviation from the Standard Model has been identified.
Ranges of the top quark and Higgs boson masses are derived as functions of
$\alpha_s(\mz)$ and $\bar{\alpha}(\mmz)$. Also discussed are consequences of
the recent precision measurement of the left-right asymmetry at SLC as well as
the impact of a top quark mass and an improved $W$ mass measurement.


title:
"A Hint From the Inter-Family Mass Hierarchy: Two Vector-Like Families
  in the TeV range"

abstract:
  Two vector-like families with masses of order 1 TeV, one of which is a
doublet of $SU(2)_L$ and the other a doublet of $SU(2)_R$, have been predicted
to exist in the context of a viable and economical SUSY composite model. One of
the many attractive features of the model is an explanation of the inter-family
mass-hierarchy for which the existence of the two vector-families is crucial.
This paper is devoted to a detailed study of the expected masses, mixings and
decay modes of the fermions belonging to the two vector-like families. The
masses of the vector-like quarks are expected to lie in the range of 500 GeV to
about 2.5 TeV, while those of the vector-like leptons are expected to be in the
range of 200 GeV to 1 TeV. Their mass pattern and decay modes exhibit certain
distinguishing features and characteristic signals. For example, when the LHC
and, possibly a future version of the SSC are built, pair-production of the
vector-like quarks would lead to systems such as ($b\overline{b}+4Z+W^+W^-$)
and ($b\overline{b}+2Z+W^+W^-$), while an $e^-e^+$ linear collider (NLC) of
suitable energy can produce appreciably a single neutral heavy lepton $N$
together with $\nu_\tau$, followed by the decay of $N$ into $(Z+\nu_\tau)
\rightarrow (e^-e^+) + \nu_\tau$. This last signal may conceivably materialize
even at LEP 200 if $N$ is lighter than about 190 GeV.


title:
Comment on the Renormalization Group Improvement in Exclusive $b\ra c $
  Transitions

abstract:
  Using rather general consideration I argue that the numerical impact of the
existing next-to-leading logarithmic summations of terms $\log{m_b/m_c}$ for
perturbative factors $\eta_A$, $\eta_V$ in the exclusive zero recoil
semileptonic transitions is irrelevant, and adopting corresponding corrections
beyond the exact one loop result for both estimating the values of these
formfactors and their theoretical uncertainty, is misleading. The central
theoretical value if taken literally is then $\eta_A\simeq 0.97$.


title: The energy dependence of the Pomeron and the eikonalized Pomeron

abstract:
  The one-to-one connection between the eikonal phase and the ratio of the
elastic and total cross section is shown. Based on new experimental data of
Collaboration CDF we analyzed intercept and power of the logarithmic growth of
the Born and total Pomeron amplitude.


title: S-wave phase shift in Lambda-pi scattering

abstract:
  We calculate the s-wave strong interaction $\Lambda$$\pi$ phase shift at the
$\Xi$ mass taking into account contributions from the ${{\frac{1}{2}}}^{-}$ and
${{\frac{3}{2}}}^{-}$ $\Sigma$ resonances. We find the S-wave phase shift to be
small, of the order of 0.3 degrees and bounded by 0.5 degrees.


title: Applied Chiral Perturbation Theory

abstract:
  I consider some selected topics in chiral perturbation theory (CHPT) as
probed at colliders such as DA$\Phi$NE. Emphasis is put on processes involving
pions in the isospin zero S-wave which require multi-loop calculations. These
include the scalar form factor of the pion, two--photon fusion into pion pairs
and $K_{\ell 4}$--decays. The physics of the chiral anomaly is briefly touched
upon


title: Higgs-Sector Solitons

abstract:
  We establish the existence of static, classically-stable, winding solitons in
renormalizable three-dimensional gauge models, with topologically trivial
target space and vacuum manifold. They are prototypes for possible analogous
particle-like excitations in the higgs sector of the standard electroweak
theory.


title: The $1/m_Q$ Expansion in QCD: Introduction and Overview

abstract:
  A mini-review of the heavy mass expansion in QCD is given. We focus on
exclusive semileptonic decays and some topics of recent interest in inclusive
decays of heavy hadrons.


title:
Analytical and numerical methods for massive two-loop self-energy
  diagrams

abstract:
  Motivated by the precision results in the electroweak theory studies of
two-loopFeynman diagrams are performed. Specifically this paper gives a
contribution to the knowledge of massive two-loop self-energy diagrams in
arbitrary and especially four dimensions.This is done in three respects firstly
results in terms of generalized, multivariable hypergeometric functions are
presented giving explicit series for small and large momenta. Secondly the
imaginary parts of these integrals are expressed as complete elliptic
integrals.Finally one-dimensional integral representations with elementary
functions are derived.They are very well suited for the numerical evaluations.


title: Nonperturbative effects in heavy quarkonia

abstract:
  An effective hamiltonian for heavy quarkonia is derived from QCD by
separating gluonic fields in background and quantum fields and neglecting
anharmonic contributions. Mesonic states with nonperturbative gluonic
components are constructed. These states are invariant under gauge changes of
the background fields and form an orthogonal basis. The effective hamiltonian
is diagonalized in this basis in a systematic $1/m$- and short distance
expansion. For very heavy quarkonia, we obtain an effective potential similar
to the phenomenological funnel potential. We compare our method to $2^{\rm nd}$
order perturbation theory in the background fields and demonstrate its
applicability even for the relatively light charmonium system. The results to
order $1/m$ for pseudoscalar meson masses and wave functions are shown and
compared with those of the Cornell model.


title: Threshold Effects on the QCD Coupling $\alpha_{\overline{MS}}$

abstract:
  The matching condition which determines the effect of a heavy quark threshold
on the running of the QCD coupling $\alpha_{\overline{MS}}$ is reviewed. The
matching scale is arbitrary to some extent. However, this affects the value of
$\alpha_{\overline{MS}}$ away from the threshold region only marginally.


title: QCD radiative enhancement of the decay b -> c cbar s

abstract:
  A substantial enhancement is found of the $b \to c\,{\overline c}\, s$ decay
rate due to the QCD interaction within the $\overline c s$ pair, which
enhancement may amount to 30\%, or more. Some general features of calculation
of the QCD radiative corrections in two first orders are discussed.


title: Lyapunov Exponent and Plasmon Damping Rate in Nonabelian Gauge Theories

abstract:
  We explain why the maximal positive Lyapunov exponent of classical SU($N$)
gauge theory coincides with (twice) the damping rate of a plasmon at rest in
the leading order of thermal gauge theory. [This is a substantially revised and
expanded version of the manuscript.]


title: One-Loop Corrections to Two-Quark Three-Gluon Amplitudes

abstract:
  We present the one-loop QCD amplitudes for two external massless quarks and
three external gluons ($\bar{q}qggg$). This completes the set of one-loop
amplitudes needed for the next-to-leading-order corrections to three-jet
production at hadron colliders. We also discuss how to use group theory and
supersymmetry to minimize the amount of calculation required for the more
general case of one-loop two-quark $n$-gluon amplitudes. We use collinear
limits to provide a stringent check on the amplitudes.


title: Penguin $B$ Decays $b\rightarrow s l^+l^-$ and $b\rightarrow s g$

abstract:
  The penguin mediated processes $b\rightarrow s g$ and $b\rightarrow s l^+l^-$
are studied. In the Standard Model, for the leptonic modes improvement in
experimental limits will put strigient bounds on the top mass, where the
present limit from $b\rightarrow s \mu^+\mu^-$ is 390 GeV. For hadronic penguin
processes, although the gluonic penguin dominates, we find the electroweak
contribution are around 30\% for the upper range allowed top mass. The
branching ratio for $B\rightarrow X_s \phi$ is predicted to be in the range
$(0.6\sim 2)\times 10^{-4}$. Effects of the charged Higgs in two Higgs doublet
models are discussed.


title:
Model independent constraints on anomalous gauge boson self-couplings
  from $e^+e^-$ colliders with longitudinally polarized beams

abstract:
  We explore the possibility of deriving model independent limits on the
anomalous trilinear electroweak gauge boson couplings from high energy
$e^+e^-\to W^+W^-$, by combining the cross sections for the different initial
and final states polarizations integrated with suitable kinematical cuts. In
the case of the CP conserving couplings the limits can be disentangled, and are
given by simple mathematical expressions. Numerical results show the advantages
of this approach, in particular the important role of polarization in improving
the bounds.


title:
Energy Spectra and Energy Correlations in the Decay $H\to ZZ\to
  \mu^+\mu^-\mu^+\mu^-$

abstract:
  It is shown that in the sequential decay $H\to ZZ\to (f_1\bar{f_1})+
(f_2\bar{f_2})$, the energy distribution of the final state particles provides
a simple and powerful test of the $HZZ$ vertex. For a standard Higgs boson, the
energy spectrum of any final fermion, in the rest frame of $H$, is predicted to
be $d\Gamma /dx\sim 1+\beta^4-2(x-1)^2$, with $\beta = \sqrt{1-4m^2_Z/m^2_H}$
and $1-\beta \le x=4E/m_H\le 1+\beta $. By contrast, the spectrum for a
pseudoscalar Higgs is $d\Gamma /dx \sim \beta^2+(x-1)^2$. There are
characteristic energy correlations between $f_1$ and $f_2$ and between $f_1$
and $\bar{f_2}$. These considerations are applied to the ``gold--plated''
reaction $H\to ZZ\to \mu^+\mu^-\mu^+\mu^-$, including possible effects of
CP--violation in the $HZZ$ coupling. Our formalism also yields the energy
spectra and correlations of leptons in the decay $H\to W^+W^-\to l^+\nu_ll^-
\bar{\nu_l}$.


title: Couplings of heavy mesons with soft pions in QCD

abstract:
  QCD sum rules are used to calculate the couplings of heavy-light quark
pseudoscalar and vector mesons ($D, D^*$ and $B, B^*$) with soft pions, both
for finite and infinitely heavy quark mass. The couplings are also computed in
the framework of a QCD relativistic potential model; in this approach the
relativistic corrections due to the light quark are relevant.


title:
Calculation of a weak nonleptonic matrix element using ``Weinberg'' sum
  rules

abstract:
  There is a ``toy'' weak matrix element which can be expressed as an integral
over the vector and axial vector spectral functions, $\rho_V (s) - \rho_A (s)$.
I review our recent evaluation of these spectral functions, the study of four
``Weinberg'' sum rules and the calculation of this matrix element.


title: An Update of the CKM Matrix

abstract:
  We update the constraints on the parameters of the quark flavour mixing
matrix $V_{CKM}$ in the standard model using the latest experimental and
theoretical results as input. We present the 95$\%$ C.L. allowed region of the
unitarity triangle and the corresponding ranges for the ratio $\vert
V_{td}/V_{ts} \vert$ and for the quantities $\sin 2\alpha$, $\sin 2\beta$ and
$\sin^2\gamma$, which characterize CP-violating rate asymmetries in $B$-decays.
The SM prediction for the $\bs$-$\bsb$ mixing ratio $\xs$ is also presented.


title: Solar Neutrino Oscillations in the Moon

abstract:
  The first three quarters of this paper consists of a pedagogical review of
neutrino oscillations, including vacuum oscillations, constant density matter
oscillations and variable density matter oscillations. We then address the
question of whether MSW solar neutrino oscillations in the moon could be
observed during a solar eclipse. For the small angle MSW solution, the effect
is unmeasureable; for the large angle solution, we find an enhancement in the
rate which can be as large as a factor of two. Since the center of the Sun, as
seen from a typical solar neutrino detector (through a transparent Earth) is
covered for roughly three hours per decade, a world-wide event rate of a few
solar neutrino events per hour might be sufficient to observe this effect. This
work constituted the undergraduate senior thesis of Brian Mason, and has been
submitted to the American Journal of Physics.


title: Renormalization of the Electroweak Theory in the Background Field Method

abstract:
  The applicability of the background field method in spontaneously broken
gauge theories is examined with new features emphasized. An explicit one loop
analysis in the electroweak theory shows that the method can be consistently
implemented in the on-shell renormalization scheme, and that the choice of the
background gauge cannot be arbitrary and must be fixed in the Landau gauge if
one calculates scattering amplitudes involving unphysical Goldstone bosons.
Some possible applications are also briefly indicated.


title: General Effective Actions

abstract:
  We investigate the structure of the most general actions with symmetry group
$G$, spontaneously broken down to a subgroup $H$. We show that the only
possible terms in the Lagrangian density that, although not $G$-invariant,
yield $G$-invariant terms in the action, are in one to one correspondence with
the generators of the fifth cohomology classes. For the special case of
$G=SU(N)_L \times SU(N)_R$ broken down to the diagonal subgroup $H=SU(N)_V$,
there is just one such term for $N\geq 3$, which for $N=3$ is the original
Wess-Zumino-Witten term.


title: Mesons with a Light Quark-Antiquark Pair and the Bethe-Salpeter Equation

abstract:
  The light quark-antiquark scattering Green's function is considered near a
meson resonance peak. The Bethe-Salpeter equation is used to write formal
expressions for the resonance width/mass ratio. Arguments are made concerning
to what extent this ratio can be calculated perturbatively, and an upper bound
is placed on the growth of this ratio as a function of radial excitation.
Certain mesons and their radial excitations are considered, as well as the more
general issue of classifying mesons in the quark model.


title: Nuclear Null Tests for Spacelike Neutrinos

abstract:
  Recently, a type of null experiment for spacelike neutrinos has been
proposed. We examine in detail a class of null tests involving nuclear beta
decay or capture in atoms and ions. The most promising candidate systems are
identified.


title: Anomalous dimension of the gluon operator in pure Yang-Mills theory

abstract:
  We present new one loop calculations that confirm the theorems of Joglekar
and Lee on the renormalization of composite operators. We do this by
considering physical matrix elements with the operators inserted at non-zero
momentum. The resulting IR singularities are regulated dimensionally. We show
that the physical matrix element of the BRST exact gauge variant operator which
appears in the energy- momentum tensor is zero. We then show that the physical
matrix elements of the classical energy-momentum tensor and the gauge invariant
twist two gluon operator are independent of the gauge fixing parameter. A
Sudakov factor appears in the latter cases. The universality of this factor and
the UV finiteness of the energy-momentum tensor provide another method of
finding the anomalous dimension of the gluon operator. We conjecture that this
method applies to higher loops and takes full advantage of the triangularity of
the mixing matrix.


title: Dynamical Chiral-Symmetry Breaking in the Dual Ginzburg-Landau Theory

abstract:
  We study the effect of QCD-monopole condensation on the dynamical
chiral-symmetry breaking by using the dual Ginzburg-Landau theory of QCD. We
formulate the Schwinger-Dyson equation and solve it numerically. The large
enhancement is found for the chiral-symmetry breaking due to QCD-monopole
condensation, which suggests the close relation between the color confinement
and the chiral-symmetry breaking.


title:
Color Confinement and Dynamical Effect of Light Quarks in the Dual
  Ginzburg-Landau Theory

abstract:
  We study nonperturbative features of QCD using the dual Ginzburg-Landau
theory. The color confinement is realized through the dual Higgs mechanism,
which is brought by QCD-monopole condensation. We investigate the infrared
screening effect on the color confinement due to the light-quark pair creation.
By solving the Schwinger-Dyson equation, we find that the dynamical
chiral-symmetry breaking is largely brought by the confining force.


title:
Extraction of $a_1$ and $a_2$ from $B\to \psi K(K^*),~ D(D^*)\pi(\rho)$
  Decays

abstract:
  Based on the factorization approach, we show that the CLEO data for the ratio
$\Gamma(B\to\psi K^*)/\Gamma(B\to \psi K)$ and the CDF measurement of the
fraction of longitudinal polarization in $B\to\psi K^*$ can be accounted for by
the heavy-flavor-symmetry approach for heavy-light form factors provided that
the form factor $F_0$ behaves as a constant, while the $q^2$ dependence is of
the monopole form for $F_1,~ A_0,~A_1$, and of the dipole behavior for $A_2$
and $V$. This $q^2$ extrapolation for form factors is further supported by
$B\to K^*\gamma$ data and by a recent QCD-sum-rule analysis. We then apply this
method to $B\to D(D^*)\pi(\rho)$ decays to extract the parameters $a_1$ and
$a_2$. It is found that $a_1(B\to D^{(*)}\pi(\rho))=1.01\pm 0.06$ and $a_2(B\to
D^{(*)}\pi(\rho))=0.23\pm 0.06\,$. Our result $a_2/a_1=0.22\pm 0.06$ thus
significantly improves the previous analysis that leads to $a_2/a_1=0.23\pm
0.11$. We argue that, contrary to what anticipated from the leading $1/N_c$
expansion, the sign of $a_2(B\to\psi\K)$ should be positive and
$a_2(B\to\psi\K)~{\large ^>_\sim}~ a_2(B\to D^{(*)}\pi(\rho))$.


title: Bose_einstein Correlations of Unstable Particles

abstract:
  Within a field theoretical formalism suited to treat inhomogeneous hot
quantum systems, we derive the two-particle correlation function for particles
having a spectral width gamma in the region of their emission. We find, that
this correlation function measures the radius R0 of the thermal source only in
case gamma*R0 > 1.


title: Parton Distributions for Low Q^2

abstract:
  We extend the MRS(A) set of parton distributions, which provides an
up-to-date description of the structure of the proton probed by hard
interactions, into the region of $Q^2$ below $5\ {\rm GeV}^2$. After
physically-motivated modifications, we obtain a smooth description of the data
on the structure function $F_2(x,Q^2)$ all the way from $Q^2 = 10^{-1}$ to
$10^3\ {\rm GeV}^2$.


title:
Deuteron Electromagnetic Form Factors in the Transitional Region Between
  Nucleon-Meson and Quark-Gluon Pictures

abstract:
  Experimental observables of the elastic eD-scattering in the region of
intermediate energies are discussed. We offer the analysis of the available
experimental data, which reproduces the results of the calculations with
popular $NN$-potentials at low energies ($Q^2\ll 1(GeV/c)^2$), but, at the same
time, provides the right asymptotic behavior of the deuteron e.m. form factors,
following from the quark counting rules, at high energies ($Q^2\gg
1(GeV/c)^2$). The numerical analysis developed allows to make certain
estimations of the characteristic energy scale, at what the consideration of
quark-gluon degrees of freedom in the deuteron becomes essential.


title:
Present and future searches with e^+e^- colliders for the neutral Higgs
  bosons of the Minimal Supersymmetric Standard Model -- the complete 1-loop
  analysis

abstract:
  New mass regions unexcluded by direct searches are revealed by an analysis of
experimental results from LEP1 using full 1-loop diagrammatic calculations of
radiative corrections in the MSSM. Simulations of experimental signal
efficiencies and background rejection factors, and full 1-loop calculations are
combined to study the sensitivity for neutral Higgs bosons at LEP2 and the NLC.
Compared with previous studies based on an Effective Potential Approach, we
identify mass regions where the discovery potential depends on the MSSM
parameters other than the top and stop masses. We propose our method of
interpretation to be adopted by the four LEP experiments for better precision.
The possibility of the experimental distinction between the Higgs boson in the
MSM and the lightest Higgs boson in the MSSM is discussed for the NLC.


title:
Phase Structure of Four-Fermion Theories at Finite Temperature and
  Chemical Potential in Arbitrary Dimensions

abstract:
  The phase structure of four-fermion theories is thoroughly investigated with
varying temperature and chemical potential for arbitrary space-time dimensions
$(2 \leq D < 4)$ by using the 1/N expansion method. It is shown that the chiral
symmetry is restored in the theory under consideration for sufficiently high
temperature and/or chemical potential. The critical line dividing the symmetric
and broken phase is given explicitly. It is found that for space-time dimension
$2 \leq D < 3$ both the first-order and second-order phase transition occur
depending on the value of temperature and chemical potential while for $3 \leq
D < 4$ only the second-order phase transition exists.


title:
Low Energy Thresholds and the Scalar Mass Spectrum in Minimal
  Supersymmetry

abstract:
  We discuss low energy threshold effects and calculate the sparticle masses in
the context of the Minimal Supersymmetric Standard Model. We pay particular
attention to the top squark and the Higgs mass parameters, and calculate the
top Yukawa corrections, taking into account the successive decoupling of each
particle at its threshold. We discuss the phenomenological implications in the
context of the radiative symmetry breaking scenario.


title: Covariant and Heavy Quark Symmetric Quark Models

abstract:
  There exist relativistic quark models (potential or MIT-bag) which satisfy
the heavy quark symmetry (HQS) relations among meson decay constants and form
factors. Covariant construction of the momentum eigenstates, developed here,
can correct for spurious center-of-mass motion contributions.Proton form factor
and M1 transitions in quarkonia are calculated. Explicit expression for the
Isgur-Wise function is found and model determined deviations from HQS are
studied. All results depend on the model parameters only. No additional ad hoc
assumptions are needed.


title: Polarized Structure Functions: Theory and Phenomenology

abstract:
  We review the theory of polarized structure functions measured in
deep-inelastic lepton-nucleon scattering, focusing on the most recent
developments. We concentrate on the structure function $g_1$, emphasizing the
phenomenological problems related to the extraction of the proton and neutron
$g_1(x,Q^2)$ from the data, and to the determination of its moments, especially
the first moment. In particular, we discuss the theoretical and experimental
uncertainties due to the $Q^2$ dependence of the data, small and large $x$
extrapolations, QCD loop corrections, higher twist corrections, and, in
connection to neutron experiments, nuclear effects. We also discuss the current
status of the sum rules satisfied by the first moment of $g_1$ and their
theoretical interpretation.


title:
On the determination of the relative sign of $a_1$ and $a_2$ from
  polarization measurements in $B^- \rightarrow \rho^- {D^*}^o$ decay

abstract:
  We point out that polarization measurements such as the longitudinal fraction
and the transverse left-right asymmetry in the Bauer-Stech-Wirbel (BSW) class
III processes involving two final vector mesons, $B^- \ra \rho^- {D^*}^o$ taken
as an example, are useful in determining the relative sign as well as the
relative magnitudes of the coefficients $a_1$ and $a_2$.


title:
Transverse tau polarization in inclusive $\bar B\to \tau \bar\nu X$
  decays

abstract:
  We calculate, in the framework of multi Higgs doublet models, the $CP$
violating transverse tau polarization, $P_\perp$, in inclusive semileptonic $B$
meson decays. We find that $P_\perp$ diverges at ${\cal O}(1/m_b^2)$ of the
heavy quark expansion. We discuss the physical reasons for this divergence and
show how to regularize it. We find large $1/m_b^2$ corrections that can
suppress the $CP$ asymmetry by as much as 30\%. The maximal allowed asymmetry
is $a_{CP}\sim0.34$. We discuss how the allowed range is expected to change in
the future.


title: Measures of fine tuning

abstract:
  Fine-tuning criteria are frequently used to place upper limits on the masses
of superpartners in supersymmetric extensions of the standard model. However,
commonly used prescriptions for quantifying naturalness have some important
shortcomings. Motivated by this, we propose new criteria for quantifying fine
tuning that can be used to place upper limits on superpartner masses with
greater fidelity. In addition, our analysis attempts to make explicit the
assumptions implicit in quantifications of naturalness. We apply our criteria
to the minimal supersymmetric extension of the standard model, and we find that
the scale of supersymmetry breaking can be larger than previous methods
indicate.


title: Cosmological Constant and Supergravity Soft Terms

abstract:
  In supergravity models, the quantum correction to the vacuum energy can be of
order $M_I^4$, if the cutoff is of order the Planck mass $M^2_{P}$ and $Str\
{\cal M}^2\ne 0$. Therefore, the tree level cosmological constant must be
nonzero (probably negative). Since the current practice of calculating soft
parameters in supergravity models assumes the vanishing tree level cosmological
constant, the supergravity calculation must be accordingly modified. This
implies that the soft parameters in supergravity has an additional contribution
depending on the nonvanishing tree level cosmological constant. A simple
quantum mechanical model mimicking this situation is also presented.


title: Sources of CP Violation in the Two-Higgs Doublet Model

abstract:
  Assuming CP violation arises solely through the Higgs potential, we develop
the most general two-Higgs doublet model. There is no discrete symmetry that
distinguishes the two Higgs bosons. It is assumed that an approximate global
family symmetry sufficiently suppresses flavor-changing neutral scalar
interactions. In addition to a CKM phase, neutral boson mixing, and superweak
effects, there can be significant CP violation due to charged Higgs boson
exchange. The value of $\epsilon'/\epsilon$ due to this last effect could be as
large as in the standard model.


title: Goldstone Bosons

abstract:
  The paper concerns the effective field theory methods used to study the low
energy structure of systems with a spontaneously broken symmetry. I first
explain how the method works in the context of quantum chromodynamics and then
discuss a few general aspects, related to the universality of effective
theories. In particular, I compare some of the effective field theories used in
condensed matter physics with those relevant for particle physics. (Talk given
at the Bose Conference, Jan.94, Calcutta, BUTP 94/17)


title: Foundations and Scope of Chiral Perturbation Theory

abstract:
  The aim of this introductory lecture is to review the arguments, according to
which the symmetry properties of the strong interaction reveal themselves at
low energies. I first discuss the symmetries of QCD, then sketch the method
used to work out their implications and finally take up a few specific issues,
where new experimental results are of particular interest to test the
predictions. (Talk given at the Workshop "Chiral Dynamics: Theory and
Experiment", July 1994, MIT, BUTP 94/18)


title: Searching for Exotic Mesons in e^+e^- Annihilation at Dafne

abstract:
  $DA{\Phi}NE$ should be useful for testing the nature of the vector mesons
directly produced in $e^-e^+$ annihilation, as well as the nature of the $C=+$
states produced in the radiative decays of these vector mesons. In the
$DA{\Phi}NE$ energy range, these latter states may have spin up to two and any
parity. Provided the background can be handled and the spin of the produced
state is known, the study of the angular distributions in these decays can
measure the parity of the produced meson as well as the ratios of the
independent production helicity amplitudes. These ratios provide sensitive
tests for quark model classification of the states, in particular the enigmatic
$f_1(1420)$. Thus, they can be used to indicate whether the mesons involved are
consistent with the usual $q \bar q$ interpretation, or whether other
interpretations like \eg\,hybrid, glueball or multiquark, are more favorable
for some of them.


title: Physics at DAPHNE

abstract:
  Proceedings of invited lecture at the Zuoz summer school on hadronic aspects
of collider physics, August 23-31, 1994, Zuoz, Switzerland. Describes the PHI
factory DAPHNE being built at Frascati, Italy, and the physics that can be done
there, with emphasis on its potential for studying CP violation.


title:
The Chiral Lagrangian parameters, $\overline{\ell}_1$,
  $\overline{\ell}_2$, are determined by the $\rho$--resonance

abstract:
  The all--important consequence of Chiral Dynamics for $\pi \pi$ scattering is
the Adler zero, which forces $\pi \pi$ amplitudes to grow asymptotically. The
continuation of this subthreshold zero into the physical regions requires a
$P$--wave resonance, to be identified with the $\rho$. It is a feature of $\pi
\pi$ scattering that convergent dispersive integrals for the $I=1$ channel are
essentially saturated by the $\rho$--resonance and are much larger than those
with $I=2$ quantum numbers. These facts predict the parameters
$\overline{\ell}_1$, $\overline{\ell}_2$ of the Gasser--Leutwyler Chiral
Lagrangian, as well as reproducing the well--known KSFR relation and
self-consistently generating the $\rho-$resonance.


title: Heavy Quarks from QCD Spectral Sum Rules

abstract:
  We summarize the recent developments on the extraction of the dynamical
properties of the heavy quarks from QCD spectral sum rules.


title:
{$K^0$}-{$\overline{K}^0$} mixing and the CKM parameters $(\rho,\eta)$
  from the Laplace sum rules

abstract:
  Using the Laplace sum rule (LSR) approach, which is less affected by the
contribution of the higher mass hadronic states than the Finite Energy Sum Rule
(FESR), we test the reliability of the existing estimate of the
$K^0$-$\overline {K}^0$ mixing parameter from the four-quark two-point
correlator. We obtain, for the renormalization group invariant $B$-parameter
$\Big[ f_K/(1.2f_\pi)\Big]^2 \hat {B}_K$, the upper bound: 0.83 and the $best$
estimate: $0.55 \pm 0.09$. Combining the previous estimate with the updated
value of $f_B\sqrt{B_B}=(1.49\pm 0.14)f_\pi$ obtained from the same LSR method,
one can deduce the $best$ fitted values $(\rho,\eta)\approx (0.41,0.09)$ of the
CKM parameters.


title:
A Probe of New Resonant Structures with Four Fermion Processes at a 1
  TeV $e^+e^-$ Collider

abstract:
  Oblique contributions from vector particles that are strongly coupled to the
known gauge bosons are calculated for the case of various observables at a 1
TeV $e^+e^-$ collider. Constraints provided by LEP 1 results are taken into
account in a model-independent way through a dispersion relation technique.
Depending on the assumed theoretical properties, mass limits of several TeV
should be observable.


title: How sharp is the chiral crossover phenomenon for realistic meson masses?

abstract:
  The mass dependence of the chiral phase transition is studied in the linear
$SU(3)\times SU(3)$ sigma-model to leading order in a $1/N_f$-expansion, $N_f$
denoting the number of flavours. For realistic meson masses we find a smooth
crossover between $T\sim181.5$ to 192.6~[MeV]. The crossover looks more rapid
in the light quark condensate than in thermodynamic quantities like the energy
and entropy densities. The change in the light quark condensate in this
temperature interval is $\sim$~50\% of the zero-temperature condensate value,
while the entropy density increases by ($5.5\pm0.8)\cdot10^{-3}$~[GeV$^3$].
Since the numerical error is particularly large in this region, we cannot rule
out a finite latent heat smaller than 0.2~[GeV/fm$^3$]. The chiral transition
is washed out for an average pseudoscalar meson octet mass of 203~[MeV]. This
gives an upper bound on the first-order transition region in the meson mass
parameter space. The corresponding ratio of critical to realistic light current
quark masses $m^{crit}_{u,d}/m_{u,d}$ is estimated as $0.26\pm0.08$. This
result is by an order of magnitude larger than the corresponding mean-field
value. Therefore the


title: Longitudinal Transitions Of Baryon Resonances in Constituent Quark Model

abstract:
  A longitudinal transition operator that satisfies the gauge invariance
requirement is introduced in constituent quark model. The corresponding
longitudinal transitions between the nucleon and baryon resonances are
calculated. We show that the study of the longitudinal coupling plays an
important role in understanding the structure of baryons.


title:
Quantum-Chromodynamic Potential Model for Light-Heavy Quarkonia and the
  Heavy Quark Effective Theory

abstract:
  We have investigated the spectra of light-heavy quarkonia with the use of a
quantum-chromodynamic potential model which is similar to that used earlier for
the heavy quarkonia. An essential feature of our treatment is the inclusion of
the one-loop radiative corrections to the quark-antiquark potential, which
contribute significantly to the spin-splittings among the quarkonium energy
levels. Unlike $c\bar{c}$ and $b\bar{b}$, the potential for a light-heavy
system has a complicated dependence on the light and heavy quark masses $m$ and
$M$, and it contains a spin-orbit mixing term. We have obtained excellent
results for the observed energy levels of $D^0$, $D_s$, $B^0$, and $B_s$, and
we are able to provide predicted results for many unobserved energy levels. Our
potential parameters for different quarkonia satisfy the constraints of quantum
chromodynamics.
  We have also used our investigation to test the accuracy of the heavy quark
effective theory. We find that the heavy quark expansion yields generally good
results for the $B^0$ and $B_s$ energy levels provided that $M^{-1}$ and
$M^{-1}\ln M$ corrections are taken into account in the quark-antiquark
interactions. It does not, however, provide equally good results for the energy
levels of $D^0$ and $D_s$, which indicates that the effective theory can be
applied more accurately to the $b$ quark than the $c$ quark.


title:
Small-X Quarks at HERA Predict the Ultra High Energy Neutrino-Nucleon
  Cross Section

abstract:
  New structure function data at small Bjorken $x$ from HERA are used along
with next-to-leading order QCD evolution to predict a cross section for
charged-current interactions of ultrahigh energy neutrinos with nucleons. This
new result is over twice the size of previous estimates and has important
implications for cosmic ray experiments now underway as well as for KM3 arrays
(cubic kilometer-scale neutrino telescopes) now in the planning stages.


title: Solution to the Perturbative Infrared Catastrophe of Hot Gauge Theories

abstract:
  The free energy of a nonabelian gauge theory at high temperature $T$ can be
calculated to order $g^5$ using resummed perturbation theory, but the method
breaks down at order $g^6$. A new method is developed for calculating the free
energy to arbitrarily high accuracy in the high temperature limit. It involves
the construction of a sequence of two effective field theories by first
integrating out the momentum scale $T$ and then integrating out the momentum
scale $g T$. The free energy decomposes into the sum of three terms,
corresponding to the momentum scales $T$, $gT$, and $g^2T$. The first term can
be calculated as a perturbation series in $g^2(T)$, where $g(T)$ is the running
coupling constant. The second term in the free energy can be calculated as a
perturbation series in $g(T)$, beginning at order $g^3$. The third term can
also be expressed as a series in $g(T)$ beginning at order $g^6$, with
coefficients that can be calculated using lattice simulations of 3-dimensional
QCD. Leading logarithms of $T/(gT)$ and of $gT/(g^2T)$ can be summed up using
renormalization group equations.


title: A Scheme for radiative CP violation

abstract:
  We present a simple model in which CP symmetry is spontaneously broken only
after the radiative corrections are taken into account. The model includes two
Higgs-boson doublets and two right-handed singlet neutrinos which induce the
necessary non-hermitian interaction. To evade the Georgi-Pais theorem, some
fine-tuning of coupling constants is necessary. However, we show that such
fine-tuning is natural in the technical sense as it is protected by symmetry.
Some phenomenological consequences are also discussed.


title: Effective Field Theory of the Linear $O(N)$ Sigma Model

abstract:
  The low energy structure of a theory containing light and heavy particle
species which are separated by a mass gap can adequately be described by an
effective theory which contains only the light particles. In this work we
present a thorough analysis of the effective field theory of the linear $O(N)$
sigma model in the spontaneously broken phase. In particular, we present a
detailed discussion of two techniques, a short-distance expansion and a method
based on loop-integrals, which can be used to explicitly evaluate the
functional relationships between the low energy constants of the effective
theory and the parameters of the underlying theory. We furthermore provide a
detailed analysis of the matching relation between the linear sigma model and
its effective theory, in order to clarify some discrepancies which can be found
in the literature.


title:
Studying $\varepsilon '/\varepsilon$ in the Chiral Quark Model:
  $\gamma_5$-Scheme Independence and NLO Hadronic Matrix Elements

abstract:
  We study the $CP$-violating, $|\Delta S| =1$ parameter $\varepsilon
'/\varepsilon$ by computing the hadronic matrix elements in the chiral quark
model. We estimate the coefficients of the next-to-leading order terms in the
chiral expansion that correspond to the operators $Q_6$ and $Q_{11}$. We
consider the impact of these corrections on the value of $\varepsilon
'/\varepsilon$. We also investigate the possibility that the chiral quark model
might drastically reduce the dimensional regularization $\gamma_5$-scheme
dependence of current evaluations of $\varepsilon '/\varepsilon$.


title:
Form Factor $A_0(q^2)$, Non Leptonic $D(B) \to PV$ Transitions and Rare
  $B \to K^* \gamma$ Decays

abstract:
  We use three-point function QCD sum rules to calculate the form factor
$A_0(q^2)$ appearing in the matrix element of the flavour-changing axial
current between the $D (B)$ state and a vector meson state. We describe the
role of this form factor in nonleptonic $D (B) \to P V$ decays and analyze the
light $SU(3)_F$ symmetry breaking effects. We also discuss a proposal to relate
the branching ratio of $B \to K^* \gamma$ to the spectrum of the semileptonic
$B \to \rho \ell \nu$ decay.


title: On another version of the twistor--like approach to superparticles

abstract:
  Considered is a worldsheet supersymmetric generalization of the D=3
Ferber--Schirafuji twistor--superparticle action.


title: Theoretical Update of the Semileptonic Branching Ratio of B Mesons

abstract:
  We reconsider the prediction of the semileptonic branching ratio of B mesons,
using a recent calculation of the radiative corrections with account for finite
quark masses in nonleptonic decays and taking into account 1/m_b^2 corrections.
For the semileptonic branching ratio we obtain B_SL =(11.8\pm 1.6)% using pole
quark masses and B_SL = (11.0\pm 1.9)% using running MS-bar quark masses. The
uncertainty is dominated by unknown higher order perturbative corrections. We
conclude that the present accuracy of the theoretical analysis does not allow
to state a significant disagreement with the experimental results. However, our
re-analysis of the decay b->ccs yields an increase of (35\pm 11)% due to
next-to-leading order corrections including mass dependent terms, which further
emphasizes the problem of the average charm quark content of the final states
in B decays. Abstract of the erratum: Some of the numerical results presented
in our paper PLB 342 (1995) 362 are affected by an error in the computer
program and need to be revised. The numerical changes are, however, marginal.
We take the opportunity to incorporate the complete results for the quark mass
dependence of the radiative corrections to the subprocess b->ccs and enlarge
the discussion of the average charm quark content in the final state, giving
the results in two different renormalization schemes and adding a figure with
charm quark content plotted vs. the semileptonic branching ratio.


title: Heavy Meson Dynamics in a QCD Relativistic Potential Model

abstract:
  We use a QCD relativistic potential model to compute the strong coupling
constant $g$ appearing in the effective Lagrangian which describes the
interaction of $0^-$ and $1^-$ $\bar q Q$ states with soft pions in the limit
$m_Q \to \infty$. We compare our results with other approaches; in particular,
in the non relativistic limit, we are able to reproduce the constituent quark
model result: $g=1$, while the inclusion of relativistic effects due to the
light quark gives $g={1 \over 3}$, in agreement with QCD sum rules. We also
estimate heavy meson radiative decay rates, with results in agreement with
available experimental data.


title: What is a low-energy theorem ?

abstract:
  We discuss the meaning of low-energy theorems (LETs) in the framework of the
effective field theory of the standard model. Particular emphasis is put on the
LET for neutral pion photoproduction off nucleons at threshold. The seemingly
controversial situation surrounding this LET is clarified.


title: ``Non-factorizable'' terms in hadronic B-meson weak decays

abstract:
  The branching ratios for the hadronic B-meson weak decays B -> J/psi K and B
-> D pi are used to extract the size of the ``non-factorizable'' terms in the
decay amplitudes. It is pointed out that the solutions are not uniquely
determined. In the B -> J/psi K case, a 2-fold ambiguity can be removed by
analyzing the contribution of this decay to B -> K l+ l-. In the B -> D pi
case, a 4-fold ambiguity can only be removed if the ``non-factorizable'' terms
are assumed to be a small correction to the vacuum insertion result.


title: $R_{had}$ at the $B$-factory

abstract:
  A systematic theoretical evaluation of the cross section for hadron
production in electron-positron collisions in the energy range just below the
$B$ meson threshold is presented which includes charm and bottom mass effects
and is accurate to order $\as^3$. The corresponding measurement in the energy
region several $GeV$ above the threshold is also discussed.


title: Gradient Approach to the Sphaleron Barrier

abstract:
  We apply the gradient approach to obtain a path over the sphaleron barrier
and to demonstrate the fermionic level crossing phenomenon. Neglecting the
mixing angle dependence and assuming that the fermions of a doublet are
degenerate in mass we employ spherically symmetric ans\"atze for the fields.
The gradient path over the barrier is smooth, even for large values of the
Higgs boson mass or of the fermion mass, where the extremal energy path
bifurcates.


title: High energy scattering in QCD and cross singularities of Wilson loops

abstract:
  We consider elastic quark-quark scattering at high energy and fixed
transferred momentum. Performing factorization of soft gluon exchanges into
Wilson line expectation value we find that there is one-to-one correspondence
between high energy asymptotics in QCD and renormalization properties of the so
called cross singularities of Wilson lines. Using this relation we show that
the asymptotic behavior of the quark-quark scattering amplitude is controlled
by a $2\times 2$ matrix of the cross anomalous dimensions. We evaluate the
matrix of cross anomalous dimension to two-loop order and study the properties
of the obtained expressions to higher loop order.


title: One More Source of Information on the Lepton Mixing Angles

abstract:
  In the framework of the Standard Model with lepton mixing the radiative decay
$\nu_i \rightarrow \nu_j \gamma$ of a neutrino of high ($E_\nu \sim 100 \,
GeV$) and super-high ($E_\nu \ge 1 \, TeV$) energy is investigated in the
Coulomb field of a nucleus. Estimates of the decay probability and ``decay
cross-section'' for neutrinos of these energies in the electric field of
nucleus permit one to discuss the general possibility of carrying out the
neutrino experiment, subject to the condition of availability in the future of
a beam of neutrinos of that high energies. Such an experiment could give unique
information on mixing angles in the lepton sector of the Standard Model which
would be independent of the specific neutrino masses if only the threshold
factor ($1 - m_j^4 / m_i^4$) was not close to zero.


title:
Minimal Quark-Lepton Symmetry Model and Possible Limits on Z'-Mass from
  TRISTAN and Lep200

abstract:
  A minimal extension of the Standard Model containing the four-color
quark-lepton symmetry is discussed. Some features of an additional $Z'$-boson
originated from this symmetry are investigated and the limits on $m_{Z'}$ from
the current TRISTAN data and the possible limits on $m_{Z'}$ from the future
LEP200 collider are obtained.


title:
On Collinearization of Quarks in Quark-Gluon Decays of Heavy
  Orthoquarqonia

abstract:
  The decay of heavy orthoquarkonium into quark-antiquark pair and two gluons
is considered. The differential probability of the decay in the tree
approximation is calculated and the final quark mass influence on the quark and
gluon distribution functions is studied. It is shown that the collinear
strengthening of the bottomonium decay probability takes place at the $u \bar
u$-, $d \bar d$- and $s \bar s$- pair production and is absent at the $c \bar
c$- production.


title:
Rare Electroweak Processes $K^0_L \to \mu^+ \mu^-$ and $K^0_L \to \gamma
  \gamma$ and Heavy Top Quark

abstract:
  A brief overview of the recent measurements of the branching ratio of the
rare $K_L^0 \to \mu^+ \mu^-$ decay in the context of their agreement with the
Standard Model (SM) is given. It is shown that KEK result well correlates with
the SM and B-physics, whereas the BNL results are in conflict with the SM with
the heavy top quark.


title: Diffractive Meson Production and the Quark-Pomeron Coupling

abstract:
  Diffractive meson production at HERA offers interesting possibilities to
investigate diffractive processes and thus to learn something about the
properties of the pomeron. The most succesful phenomenological description of
the pomeron so far assumes it to couple like a $C = +1$ isoscalar photon to
single quarks. This coupling leads, however, to problems for exclusive
diffractive reactions. We propose a new phenomenological pomeron vertex, which
leads to very good fits to the known data, but avoids the problems of the old
vertex.


title: A modified discrete sine-Gordon Model

abstract:
  We modify the recently proposed model of Speight and Ward to make it possess
time dependent solutions. We find that for each lattice spacing and for each
velocity of the sine Gordon kink we can find a modification of the model for
which this kink is a solution. We find that this model has really 3
``kink-like" solutions; the original kink, the static kink and a further kink
moving with velocity $v\sim0.97$. We discuss various properties of the model,
from the point of view of its usefulness for numerical simulations.


title:
Higher-Order Perturbative Corrections to $b\to c$ Transitions at Zero
  Recoil

abstract:
  We estimate the two-loop perturbative corrections to zero-recoil matrix
elements of the flavour-changing currents $\bar c\,\gamma^\mu b$ and $\bar
c\,\gamma^\mu\gamma_5\,b$ by calculating the terms of order $n_f\,\alpha_s^2$
and substituting the dependence on the number of flavours by the first
coefficient of the $\beta$-function. Both for vector and axial vector currents,
we find moderate two-loop corrections below 1\% in magnitude. Using the
Brodsky--Lepage--Mackenzie prescription to set the scale in the
order-$\alpha_s$ corrections in the $\overline{\rm MS}$ scheme, we obtain
$\mu_V\simeq 0.92\sqrt{m_b m_c}$ and $\mu_A\simeq 0.51\sqrt{m_b m_c}$ in the
two cases. These scales are sufficiently large for perturbation theory to be
well-behaved. The implications of our results to the extraction of $|\,V_{cb}|$
are briefly discussed.


title: Two-loop mixing of dimension-five flavor-changing operators

abstract:
  We calculate the two-loop QCD mixing of the dimension-five flavor-changing
operators that arise in the Standard Model after integrating out the $W$, $Z$
and Higgs bosons and the top-quark, i.e.~the mixing among gluonic and photonic
magnetic moment operators. Our calculation completes the two-loop anomalous
dimension matrix of operators that govern low energy flavor-changing processes.
It is an important ingredient of the next-to-leading calculation of the $B
\rightarrow X_s \gamma$ decay rate.


title: Target Mass Effects in QCD Bjorken Sum Rule

abstract:
  We investigate the target mass effects in QCD Bjorken sum rule. The magnitude
of the target mass correction is estimated in a variety of methods employing
positivity bound as well as the experimental data for the asymmetry parameters.
It turns out that the target mass correction is sizable at low $Q^2$ of the
order of a few GeV$^2$, where the QCD correction is significant. We show that
there exists uncertainty due to target mass effects in determining the QCD
effective coupling constant $\alpha_s(Q^2)$ from the Bjorken sum rule.


title: Physics at Low x

abstract:
  The QCD expectations concerning the deep inelastic lepton - hadron scattering
at low $x$ and their phenomenological implications for HERA are summarised.
Theoretical predictions for the structure function $F_2(x,Q^2)$ based on the
leading log$1/x$ resummation are presented and compared with the results
obtained from the Altarelli-Parisi equations. Theoretical predictions are
confronted with the recent data from HERA. The role of studying the final
states in deep inelastic scattering for revealing the dynamics at low $x$ is
emphasised and some dedicated measurements like deep inelastic plus jet events,
transverse energy flow and dijet production in deep inelastic scattering are
discussed.


title:
Bounds on Radii and Magnetic Dipole Moments of Quarks and Leptons from
  LEP, SLC and HERA

abstract:
  Leptons, quarks and gauge bosons are assumed to be pointlike particles in the
Standard Model. Stringent bounds on the radii of quarks and leptons and their
weak anomalous magnetic moments can be derived from the high-precision
measurements at LEP and SLC. We find a model-independent bound of $R\lsim
10^{-17}cm$ for quark and lepton radii. HERA will provide complementary
information on the electromagnetic static properties of the quarks and the
parameters of the charged quark currents.


title:
Improved Higgs Mass Stability Bound in the Standard Model and
  Implications for Supersymmetry

abstract:
  We re-examine the lower bound on the mass of the Higgs boson, $M_H$, from
Standard Model vacuum stability including next-to-leading-log radiative
corrections. This amounts to work with the full one-loop effective potential,
$V(\phi)$, improved by two-loop RGE, and allows to keep control of the scale
invariance of $V$ in a wide range of the $\phi$-field. Our results show that
the bound is ${\cal O}\ (10\ GeV)$ less stringent than in previous estimates.
In addition we perform a detailed comparison between the SM lower bounds on
$M_H$ and the supersymmetric upper bounds on it. It turns out that depending on
the actual value of the top mass, $M_t$, the eventually measured Higgs mass can
discard the pure SM, the Minimal Supersymmetric Standard Model or both.


title:
Kosterlitz-Thouless Phase Transition In The Two Dimensional Linear Sigma
  Model

abstract:
  We investigate the O(N) symmetric linear $\sigma$-model in two dimensions by
means of an exact nonperturbative evolution equation. The perturbative infrared
divergences are absent in this formulation. We use a simple approximative
solution of the flow equation which corresponds to a derivative expansion for
the effective action. For N=2 this gives a good picture of the
Kosterlitz-Thouless phase transition.


title:
Searching for Anomalous Weak Couplings of Heavy Flavors at the SLC and
  LEP

abstract:
  The existence of anomalous electric($\tilde \kappa$) and/or
magnetic($\kappa$) dipole moment couplings between the heavy flavor fermions
($c,b,\tau$) and the $Z$ boson can cause significant shifts in the values of
several electroweak observables currently being probed at both the SLC and LEP.
Using the good agreement between existing data and the predictions of the
Standard Model we obtain strict bounds on the possible strength of these new
interactions for all of the heavy flavors. The decay $Z\rightarrow b\bar b$,
however, provides some possible hint of new physics. The corresponding
anomalous couplings of $\tau$'s to photons is briefly examined.


title: Pulsar Bound on the Photon Electric Charge Reexamined

abstract:
  If photons had a small electric charge $Q_\gamma$ their path in the galactic
magnetic field would be curved, leading to a time delay between photons of
different frequency from a distant source. Cocconi's previous application of
this argument led to a limit which is too restrictive by a factor of about 200;
the corrected bound is $Q_\gamma/e\lapprox10^{-29}$.


title:
Commensurate Scale Relations: Precise Tests of Quantum Chromodynamics
  without Scale or Scheme Ambiguity

abstract:
  We derive commensurate scale relations which relate perturbatively calculable
QCD observables to each other, including the annihilation ratio, the heavy
quark potential, tau decay, and radiative corrections to structure function sum
rules. The ratio of scales $Q_A/Q_B$ is unique at leading order and guarantees
that the observables A and B pass through new quark thresholds at the same
physical scale. In higher orders a different renormalization scale $Q^{n*}$ is
assigned for each order n in the perturbative series such that the coefficients
of the series are identical to that of a conformally invariant theory. QCD can
thus be tested in a new and precise way by checking that the effective charges
of observables track both in their relative normalization and in their
commensurate scale dependence. The commensurate scale relations which relate
the radiative corrections to the annihilation ratio to the radiative
corrections for the Bjorken and Gross-Llewellyn Smith sum rules provides the
generalization of the Crewther relation to non-conformal gauge theory.


title: Pion and Sigma Polarizabilities and Radiative Transitions

abstract:
  Fermilab E781 plans measurements of gamma-Sigma and $\gamma$-pion
interactions using a 600 GeV beam of Sigmas and pions, and a virtual photon
target. Pion polarizabilities and radiative transitions will be measured in
this experiment. The former can test a precise prediction of chiral symmetry;
the latter for a_1(1260) ----> pi + gamma is important for understanding the
polarizability. The experiment also measures polarizabilities and radiative
transitions for Sigma hyperons. The polarizabilities can test predictions of
baryon chiral perturbation theory. The radiative transitions to the
Sigma*(1385) provide a measure of the magnetic moment of the s-quark. Previous
experimental and theoretical results for gamma-pi and gamma-Sigma interactions
are given. The E781 experiment is described.


title:
Vacuum oscillation solution to the solar neutrino problem in standard
  and non-standard pictures

abstract:
  The neutrino long wavelength (just-so) oscillation is revisited as a solution
to the solar neutrino problem. We consider just-so scenario in various cases:
in the framework of the solar models with relaxed prediction of the boron
neutrino flux, as well as in the presence of the non-standard weak range
interactions between neutrino and matter constituents. We show that the fit of
the experimental data in the just-so scenario is not very good for any
reasonable value of the $^8B$ neutrino flux, but it substantially improves if
the non-standard $\tau$-neutrino--electron interaction is included. These new
interactions could also remove the conflict of the just-so picture with the
shape of the SN 1987A neutrino spectrum. Special attention is devoted to the
potential of the future real-time solar neutrino detectors as are
Super-Kamiokande, SNO and BOREXINO, which could provide the model independent
tests for the just-so scenario. In particular, these imply specific deformation
of the original solar neutrino energy spectra, and time variation of the
intermediate energy monochromatic neutrino ($^7Be$ and $pep$) signals.


title:
Heavy-Neutrino Chirality Enhancement of the Decay $K_L -> e\mu $ in
  Left-Right Symmetric Models

abstract:
  We study the decay $K_L -> e\mu$ in minimal extensions of the Standard Model
based on the gauge groups $SU(2)_L x U(1)_Y$ and $SU(2)_R x SU(2)_L x
U(1)_{B-L}$, in which heavy Majorana neutrinos are present. In $SU(2)_L x
U(1)_Y$ models with chiral neutral singlets, $B(K_L -> e\mu )$ cannot be much
larger than $5 x 10^{-15}$ without violating other low-energy constraints. In
$SU(2)_L x SU(2)_R x U(1)_{B-L}$ models, we find that heavy-neutrino-chirality
enhancements due to the presence of left-handed and right- handed currents can
give rise to a branching ratio close to the present experimental limit $B(K_L
-> e \mu)< 3.3 x 10^{-11}$.


title: Theoretical Aspects of Single-Spin Asymmetries Studies

abstract:
  We consider theoretical background for experimental measurements of
single-spin asymmetries. We stress the non-perturbative QCD aspects of observed
asymmetries in hadronic reactions.


title: Proposal for a Simple Model of Dynamical SUSY Breaking

abstract:
  We discuss supersymmetric $SU(2)$ gauge theory with a single matter field in
the $I=3/2$ representation. This theory has a moduli space of exactly
degenerate vacua. Classically it is the complex plane with an orbifold
singularity at the origin. There seem to be two possible candidates for the
quantum theory at the origin. In both the global chiral symmetry is unbroken.
The first is interacting quarks and gluons at a non-trivial infrared fixed
point -- a non-Abelian Coulomb phase. The second, which we consider more
likely, is a confining phase where the singularity is simply smoothed out. If
this second, more likely, possibility is realized, supersymmetry will
dynamically break when a tree level superpotential is added. This would be the
simplest known gauge theory which dynamically breaks supersymmetry.


title:
Localized Energy Deposition in Neutrino Telescopes: a Signature of "New
  Physics"

abstract:
  A class of phenomena either not contained in the Standard Model or in its
perturbative treatment (multiple W/Z production, compositeness of quarks and
leptons) leads to a large energy deposition in neutrino telescopes within a
rather small volume. The shape of the particle distribution arising from such
phenomena is estimated.


title: Red giant bound on the axion-electron coupling reexamined

abstract:
  If axions or other low-mass pseudoscalars couple to electrons (``fine
structure constant'' $\alpha_a$) they are emitted from red giant stars by the
Compton process $\gamma+e\to e+a$ and by bremsstrahlung $e+(Z,A)\to (Z,A)+e+a$.
We construct a simple analytic expression for the energy-loss rate for all
conditions relevant for a red giant and include axion losses in evolutionary
calculations from the main sequence to the helium flash. We find that
$\alpha_a\lapprox0.5\mn(-26)$ or $m_a\lapprox 9\,\meV/\cos^2\beta$ lest the red
giant core at helium ignition exceed its standard mass by more than
$0.025\,\MM_\odot$, in conflict with observational evidence. Our bound is the
most restrictive limit on $\alpha_a$, but it does not exclude the possibility
that axion emission contributes significantly to the cooling of ZZ~Ceti stars
such as G117--B15A for which the period decrease was recently measured.


title: Particle Hamiltonian and Perturbative Gauge Theories

abstract:
  We discuss the Hamiltonian formulation of the Schwinger proper-time method of
calculating Green functions in gauge theories. Instead of calculating Feynman
diagrams, we solve the corresponding Dyson-Schwinger equations. We express the
solutions in terms of vertex operators, which consist of the zero modes of the
vertex operators appearing in string theories. We show how color decomposition
arises in this formalism at tree level. At the one-loop level, we arrive at
expressions similar to those obtained in the background gauge. In both cases,
no special gauge-fixing procedure is needed.


title: Parton Distributions in Nuclei

abstract:
  We discuss two topics in this talk. One is a brief overview of nuclear parton
distributions, and the other is SU(2)-flavor-symmetry breaking in {\it nuclear}
antiquark distributions. First, we show that nuclear structure functions
$F_2^A(x)$ could be explained in a $Q^2$ rescaling model with parton
recombination effects. Then, nuclear gluon distributions are discussed in this
parton model. We point out other interesting distributions for future
investigations. Second, $\bar u-\bar d$ distributions in nuclei are discussed
in order to shed light on nuclear modification of the $\bar u-\bar d$
distribution. -------------------- * This talk was supported by the Yamada
Science Foundation.


title:
QCD Analysis of Inclusive $\Delta S=1,2$ Transitions: The $|\Delta
  I|=1/2$ Rule

abstract:
  The interplay of QCD in $\Delta S=1,2$ non-leptonic weak transitions can be
rigorously analyzed, at the inclusive level, by studying the 2--point functions
associated with the corresponding $\Delta S=1,2$ effective Hamiltonians. The
next-to-leading order calculation of these correlators shows a huge ($\gsim
100\%$) gluonic enhancement of the $|\Delta I|=1/2$ channel, providing a
qualitative understanding of the $|\Delta I|=1/2$ rule within QCD.


title:
Evidence on $qq\bar q\bar q$ Hadron Spectrum from $\gamma\gamma\to
  vector\,meson\,vector\, meson$ Reactions?

abstract:
  The $\gamma\gamma\to\rho^0\rho^0\to 4 \pi$ reaction shows a broad
"resonance"at 1.5 GeV with no counterpart in the $\rho^+\rho^-$ channel. This
$(J^P,J_z)=(2^+,2)$, $I=0$, and $2$ resonance is considered as a candidate for
a $qq\bar q\bar q$ state. We show, however, that it can also be explained by
potential scattering of $\rho^0\rho^0$ via the $\sigma-$ exchange.


title: Signals for Supersymmetry at HERA

abstract:
  We summarize two sets of signals at HERA in supersymmetric models with
explicitly broken R-parity. (1) The resonant production of single squarks
through an operator $L_1Q_i{ \bar D}_j$. (2) The MSSM production of a squark
and a slepton followed by R-parity violating decays via the operators
$L_iQ_j{\bar D}_k$. The first case allows for a very large mass reach:
$m_{\tilde q}\leq 275\gev$ for moderate couplings. For masses $\sim 100\gev$
couplings down to $\lam\geq10^{-3}$ can be probed. In the second case the
production mechanism is independent of the R-parity violating Yukawa couplings.
The full generation structure and very low couplings, $10^{-6}$(!!), can be
probed. In the most optimistic case the mass reach is $170,195,205\gev$ for the
operators $L_{\tau,\mu,e}Q{\bar D}$ respectively. We conclude that HERA offers
a {\it very promising} discovery potential for \rpv\ SUSY.}}


title: Stability of Modified Electroweak Strings

abstract:
  We discuss the stability of an electroweak string with axions in its core,
which give to the configuration a quasi-topological property, and compare it
with other modifications using instantons in the thin wall approximation.


title: Lattice Gauge Theory: Status Report 1994

abstract:
  We report on recent developments and results from Lattice Gauge Theory. These
include determinations of the strong coupling constant $\alpha_s$ and the
b-quark mass $M_b$ and an update on the Kaon B parameter $B_K$. Lattice results
for heavy meson decay constants and semileptonic B and D meson decay form
factors are reviewed. The first attempts to study the Isgur-Wise function and
the radiative Penguin decay process, $B \rightarrow K^*\,\gamma$, on the
lattice are discussed. (Review talk presented ICHEP 94, Glasgow, July 1994)
OHSTPY-HEP-T-94-016


title: Excited Heavy Baryons in the Bound State Picture

abstract:
  The orbitally excited heavy quark baryons are studied in the Callan Klebanov
bound state model with heavy spin symmetry. First, a compact description of the
large $N_c$, infinite heavy quark mass bound state wavefunctions and the
collective quantization is given. In order to study the kinematical corrections
due to finite masses we motivate an approximate Schrodinger-like equation for
the bound state. The effective potential in this equation is compared with the
quadratic approximation (spherical harmonic oscillator) to it. This oscillator
approximation is seen to be not very accurate. It is noted that the present
experimental information cannot be even qualitatively understood with the usual
light sector chiral Lagrangian containing only light pseudoscalar mesons. The
addition of light vector mesons helps to overcome this problem.


title: Gluon fragmentation to $^1D_2$ quarkonia

abstract:
  Gluon fragmentation to heavy $J^{PC}=2^{-+}$ quarkonia is studied herein. We
compute these D-wave states' polarized fragmentation functions and find that
they are enhanced by large numerical prefactors. The prospects for detecting
the lowest lying $^1D_2$ charmonium state at the Tevatron are discussed.


title:
Pion Polarizability, Radiative Transitions, and Quark Gluon Plasma
  Signatures

abstract:
  Can one expect gamma rays rates from the QGP to be higher than from the hot
hadronic gas phase? Xiong, Shuryak, Brown (XSB) calculate photon production
from a hot hadronic gas via the reaction $\pi^- + \rho^0 \rightarrow \pi^- +
\gamma$. They assume that this reaction proceeds through the a$_1$(1260). They
also use their estimated a$_1$ radiative width to calculate the pion
polarizability; following a connection noted previously by Holstein. However,
for a$_1$(1260) $\rightarrow \pi \gamma$, the experimental radiative width is
more than two times less than the value 1.4 MeV estimated and used by XSB. We
describe how the gamma production reaction can be studied in Fermilab E781 (via
the inverse reaction, with detailed balance) via the Primakoff reaction $\pi^-
+ \gamma \rightarrow \pi^- + \rho^0$. Such a study can provide the data base
for evaluations of the utility of gamma production experiments in QGP searches.
One can experimentally check the a$_1$ dominance assumption of XSB. A
remeasurement of the a$_1(1260)$ radiative width and of the pion polarizability
in Fermilab E781 will also allow us to reevaluate the consistency of their
expected relationship.


title: Chiral Restoration in the Early Universe: Pion Halo in the Sky

abstract:
  < \psibarpsi > vanishing above $T_c$ indicates chiral symmetry restoration at
high $T$. But is it the old $T=0$ chiral symmetry that is `restored'? In this
talk, I report on the spacetime quantization of the BPFTW effective action for
quarks in a hot environ. The fermion propagator is known to give a
pseudo-Lorentz invariant particle pole as well as new spacelike cuts. Our
quantization shows that the spacelike cuts directly lead to a thermal vacuum
that is a generalized NJL state, with a curious $90^{o}$ phase. This $90^{o}$
is responsible for < \psibarpsi > vanishing at high $T$. The thermal vacuum is
invariant under a new chiral charge, but continues to break the old zero
temperature chirality. Our quantization suggests a new class of order
parameters that probe the physics of these spacelike cuts. In usual scenario,
the pion dissociates in the early alphabet soup. With this new understanding of
the thermal vacuum, the pion remains a Nambu-Goldstone particle at high $T$,
and will not dissociate. It propagates at the speed of light but with a halo.


title:
Spacetime Quantization of BPFTW Action: Spacelike Plasmon Cut \& New
  Phase of the Thermal Vacuum

abstract:
  In this paper, we perform the quantization of the nonlocal BPFTW effective
action in coordinate space. The action is made local by using a conjugate set
of auxiliary fields. The action summarizes the properties of quark propagation
through a hot environ. The fermion propagator shows a pseudo-Lorentz invariant
particle pole as well as a pair of conjugate spacelike plasmon cut. We relate
the cuts to the homogeneous solutions of the local equations of motion for
auxiliary fields. Our quantization shows how the spacelike cut produces a
$90^{o}$ phase factor in the thermal vacuum at high $T$. This phase factor is
responsible for the vanishing of $ \psibarpsi $ at high $T$.


title: Asymptotic Behavior of the Correlator for Polyakov Loops

abstract:
  The asymptotic behavior of the correlator for Polyakov loop operators
separated by a large distance $R$ is determined for high temperature QCD. It is
dominated by nonperturbative effects related to the exchange of magnetostatic
gluons. To analyze the asymptotic behavior, the problem is formulated in terms
of the effective field theory of QCD in 3 space dimensions. The Polyakov loop
operator is expanded in terms of local gauge-invariant operators constructed
out of the magnetostatic gauge field, with coefficients that can be calculated
using resummed perturbation theory. The asymptotic behavior of the correlator
is $\exp(-MR)/R$, where $M$ is the mass of the lowest-lying glueball in
$(2+1)$-dimensional QCD. This result implies that existing lattice calculations
of the Polyakov loop correlator at the highest temperatures available do not
probe the true asymptotic region in $R$.


title:
How to Measure the $Q\overline{Q}$ Potential in a Light-Front
  Calculation

abstract:
  A scheme is developed which shows how one would, given a light-front
Hamiltonian for QCD, extract the $Q\overline{Q}$ potential, i.e. the quantity
which corresponds to the potential between two infinitely heavy quarks in a
rest frame, from a light-front calculation. The resulting potential will in
general depend on the direction along which the infinitely heavy sources are
separated and thus provides a direct probe of violations of rotational
invariance in a physical observable. Furthermore, easy comparison to data from
$c\overline{c}$ and $b\overline{b}$ spectroscopy and to lattice data is
possible. The scheme may thus be very helpful in constructing a light-front
Hamiltonian through an iterative procedure.


title: Generations of Quarks and Leptons from Noncompact Horizontal Symmetry

abstract:
  The three chiral generations of quarks and leptons may be generated through a
spontaneous breakdown of the noncompact horizontal gauge symmetry $G_{H}$ which
governs, together with the standard gauge symmetry ${SU(3) \times SU(2) \times
U(1)}$, the world in a vectorlike manner. In a framework of supersymmetric
theory, the simplest choice ${G_{H}=SU(1,1)}$ works quite well for this
scenario in which quarks, leptons and Higgses belong to infinite dimensional
unitary representation of $SU(1,1)$. The relevance of the scenario to the
hierarchical structure of their Yukawa coupling matrices are discussed.


title: All Around the Spinless Salpeter Equation

abstract:
  We review some important topics related to the semirelativistic description
of bound states by the spinless Salpeter equation: the special case of the
Coulomb interaction, numerical approximation methods, and a way to avoid the
problematic square-root operator of the relativistic kinetic energy.


title: Monte Carlo Simulations for RHIC Spin Physics

abstract:
  Direct photon production in longitudinally polarised proton-proton collisions
offers the most direct and unproblematic possibility to determine the polarised
gluon distribution of a proton. This information could play a major role for
improving our understanding of the nucleon structure and QCD in general. It is
hoped that such experiments will be done at RHIC. We present results of
detailed Monte Carlo simulations using a code called {\sc SPHINX}. We find that
for RHIC energies and large gluon polarisation the Compton graph dominates
allowing for a direct test of $\Delta g$. Triggering on away-side jets with the
envisaged jet-criteria should allow to obtain more detailed information on
$\Delta g(x)$. The photon asymmetry resulting from the asymmetry of produced
$\pi^0$'s provides an additional signal, which is complementary to the other
two. For small gluon polarisation, i.e. $\Delta g \le 0.5$ or very soft
polarised gluon-distributions the envisaged experiments will require a highly
sophisticated simulation and large statistics to extract more than upper bounds
for $|\Delta g(x)|$.}


title: Sphinx: Monte Carlo Program for Polarised Nucleon-Nucleon Collisions

abstract:
  This program can be used to simulate polarised nucleon - nucleon collisions
at high energies. Spins of colliding particles are taken into account. The
program allows to calculate cross sections for various processes.


title: Induced Nucleation in Weak First Order Phase Transition

abstract:
  We study induced nucleation by considering the accumulation rate of shrinking
subcritical bubbles. We derive the probability for a collection of subcritical
bubbles to form a critical bubble, and argue that this mechanism could well
play a role in electroweak phase transitions if the Higgs is heavy.


title:
Implications of a light stop for the spontaneous CP breaking at finite
  temperature in a nonminimal supersymmetric standard model

abstract:
  We study the implications of a light stop for the spontaneous CP breaking at
finite temperature in the Higgs sector of the Minimal Supersymmetric Standard
Model with a gauge singlet. Assuming CP conservation at zero temperature, we
show that the presence of a large mixing between the left- and the right-handed
stops can trigger easily the spontaneous breaking of CP inside the bubbles
nucleated during the electroweak phase transition. This allows to avoid the
fine-tuning among the vacuum expectation values in the region of interest for
the generation of the baryon asymmetry, namely the bubble walls, which has been
recently analized.


title: Intercommutation of Z-string loops violates baryon number

abstract:
  We show that delinking of Z-string loops changes helicity and thus violates
baryon number. The key point is that an unlinked vortex loop can not be
twisted. Helicity of an eventual magnetic twist when averaged in time is zero.


title: Updated Parameter Limits of the Left-Right Symmetric Model

abstract:
  Bounds of the neutral current sector parameters of the left-right symmetric
model are investigated taking into account the low-energy data, LEP-data and
CDF-result for the top mass $m_t=174\pm 10^{+13}_{-12}$. It is found that in
the case of the minimal scalar sector with a left- and a right-handed triplet
and a bidoublet Higgses the mass of the heavy neutral gauge boson $M_{Z'}$
should be larger than 1.2 TeV, assuming equal left- and right-handed gauge
couplings and a negligible VEV of the left-handed triplet. For larger values of
the ratio $g_L/g_R$ smaller values of $M_{Z'}$ are allowed.


title:
Quark Model, Large Order Behavior and Nonperturbative Wave Functions in
  QCD

abstract:
  We discuss a few, apparently different (but actually, tightly related)
problems:
  1. The relation between QCD and valence quark model,
  2. The evaluation of the nonlocal condensate $ \la \bar{q}(x)q(0)\ra $, its
relation to heavy-light $\bar{q}Q$ quark system and to constituent quark mass,
  3. The asymptotic behavior of the nonperturbative pion wave function
$\psi(\k, x)$ at $x\rightarrow 0,~1, \k \rightarrow \infty$ and
  4. The large order behavior of perturbative series.
  The analysis is based on such general methods as dispersion relations,
duality and PCAC. We use the steepest descent method (also known as
semiclassical, or instanton calculus), introduced by Lipatov, in order to
calculate the $n-$th moment of the $\psi(\k, x)$ with result
$\la\vec{k}_{\perp}^{2n}\ra \sim n!$. This information is converted into the
fixing of the asymptotic behavior of $wf$ at large $\k$. This behavior it turns
out to be Gaussian commonly used in the phenomenological analyses.The same
method determines the asymptotic behavior of the mixed local vacuum condensates
$\la\bar{q}G_{\mu\nu}^nq\ra\sim n!$ at large $n$ as well as the nonlocal vacuum
condensate $ \la \bar{q}(x)q(0)\ra $ which is naturally arises in the
description of the heavy-light $\bar{q}Q$ quark system. The relation between
nonlocal condensate and constituent quark mass is also discussed.


title: Reduced Neutrino Opacities and the SN 1987A Signal

abstract:
  Axial-vector interactions of neutrinos and axions with a medium are based on
structure functions which cannot be calculated in simple perturbative terms for
nuclear densities. We use the SN~1987A neutrino signal duration to estimate the
range of allowed neutrino opacities of a supernova (SN) core. We perform
numerical simulations of the evolution from the hot, lepton-rich post-collapse
stage to the cold, deleptonized neutron star and compare the predicted neutrino
signal characteristics with the SN~1987A data. Besides the neutrino opacities
we vary the mass, temperature profile, and equation of state of the initial
model. Within plausible limits of these quantities the neutrino opacity cannot
be much smaller than its ``standard'' value. This limits the width of the
spin-density structure function to much smaller values than indicated by a
perturbative calculation, implying that bremsstrahlung processes such as axion
emission probably saturate at around 10\% nuclear density. A substantial
suppression at yet larger densities that might have been expected does not seem
to occur.


title:
Flavour changing top quark decay within the minimal supersymmetric
  standard model

abstract:
  We present the results of the gluino and scalar quarks contribution to the
flavour changing top quark decay into a charm quark and a photon, gluon or a
$Z^0$\ boson within the minimal supersymmetric standard model. We include the
mixing of the scalar partners of the left and right handed top quark. This
mixing has several effects, the most important of which are to greatly enhance
the c Z decay mode for large values of the soft SUSY breaking scalar mass
$m_S$\ and to give rise to a GIM--like suppresion in the c $\gamma$\ mode for
certain combinations of parameters.


title:
Non-Universal GUT Corrections to the Soft Terms and their Implications
  in Supergravity Models

abstract:
  Potentially large non-universal corrections to the soft supersymmetry
breaking parameters arise from their evolution between the Planck and the
grand-unification scales. We detail typical patterns of non-universality in GUT
models, as well as elaborate on their propagation to the weak scale and on
their low-energy implications. Possible corrections to the different scalar
quark and lepton masses and the Higgs and the gaugino-Higgsino sector
parameters are described in detail, and new allowed regions of the parameter
space are pointed out. In particular, the patterns studied often lead to
heavier Higgsinos and $t$-scalar. One-loop GUT threshold corrections to the
soft parameters are also discussed and shown to be important.


title: Zero-threshold expansion of two-loop self-energy diagrams

abstract:
  An algorithm is constructed to derive a small momentum expansion for two-loop
two-point diagrams in all cases where, due to the presence of physical
thresholds, there are singularities at zero external momentum. The coefficients
of this ``zero-threshold'' expansion are calculated analytically for arbitrary
masses. Numerical examples, using diagrams occurring in the Standard Model,
illustrate the convergence of the expansion below the first non-zero threshold.


title: Chiral Technicolor and Precision Electroweak Measurements

abstract:
  I consider the possibility that electroweak symmetry is broken by a strongly
interacting chiral gauge theory. I argue that some of the discrepancies between
precision electroweak measurements and the predictions of QCD-like technicolor
models can be resolved if technicolor is a chiral gauge theory. I present a toy
technicolor model which demonstrates this idea, and gives $ m_t \gg m_b$, with
a small value for $\Delta\rho_* \equiv \alpha T $, and small corrections to $Z
\rightarrow b \overline{b}$.


title: The Energy-Energy Correlation Function Revisited

abstract:
  The ${\cal O}(\alpha_s^2)$ coefficient of the energy-energy correlation
function (EEC) has been calculated by four groups with differing results. This
discrepancy has lead to some confusion over how to measure the strong coupling
constant using the EEC and the asymmetry of the energy-energy correlation
function (AEEC) in electron-positron annihilation at the $Z$ resonance. For
example, SLD average the four values of $\alpha_s$ extracted from each of the
different calculations. To resolve this situation, we present a new calculation
of this coefficient using three separate numerical techniques to cancel the
infrared poles. All three methods agree with each other and confirm the results
of Kunszt and Nason that form the benchmark for other ${\cal O}(\alpha_s^2)$
quantities. As a consequence, the central values and theoretical errors of the
strong coupling constant derived by SLD from the EEC and AEEC are altered.
Using the SLD data, we find, $\alpha_s^{EEC}(M_Z^2) =
0.125^{+0.002}_{-0.003}~({\rm exp.}) \pm 0.012 ~({\rm theory})$ and
$\alpha_s^{AEEC}(M_Z^2) = 0.114\pm 0.005~({\rm exp.}) \pm 0.004 ~({\rm
theory})$.


title: Thermal Phase Mixing During First Order Phase Transitions

abstract:
  The dynamics of first order phase transitions are studied in the context of
(3+1)-dimensional scalar field theories. Particular attention is paid to the
question of quantifying the strength of the transition, and how `weak' and
`strong' transitions have different dynamics. We propose a model with two
available low temperature phases separated by an energy barrier so that one of
them becomes metastable below the critical temperature $T_c$. The system is
initially prepared in this phase and is coupled to a thermal bath.
Investigating the system at its critical temperature, we find that `strong'
transitions are characterized by the system remaining localized within its
initial phase, while `weak' transitions are characterized by considerable phase
mixing. Always at $T_c$, we argue that the two regimes are themselves separated
by a (second order) phase transition, with an order parameter given by the
fractional population difference between the two phases and a control parameter
given by the strength of the scalar field's quartic self-coupling constant. We
obtain a Ginzburg-like criterion to distinguish between `weak' and `strong'
transitions, in agreement with previous results in (2+1)-dimensions.


title: CP Violation

abstract:
  We review the present status of the Standard Model of CP violation, which is
based on a complex phase in the Cabibbo-Kobayashi- Maskawa (CKM) matrix. So far
CP violation has been observed only in $K^0-\Kbar$ mixing, consistent with a
sizable phase. The implications of future CP nonconserving measurements in $K$
and $B$ decays are discussed within the model. Direct CP violation in $K\to
2\pi$ may be observed in the near future, however this would not be a powerful
test of the model. $B$ decays provide a wide variety of CP asymmetry
measurements, which can serve as precise tests of the Standard Model in cases
where the asymmetry is cleanly related to phases of CKM matrix elements. Some
of the most promising cases are discussed.


title: Hadroproduction and Polarization of Charmonium

abstract:
  In the limit of heavy quark mass, the production cross section and
polarization of quarkonia can be calculated in perturbative QCD. We study the
$p_\perp$-averaged production of charmonium states in $\pi N$ collisions at
fixed target energies. The data on the relative production rates of $\jp$ and
$\chi_J$ is found to disagree with leading twist QCD. The polarization of the
$\jp$ indicates that the discrepancy is not due to poorly known parton
distributions nor to the size of higher order effects ($K$-factors). Rather,
the disagreement suggests important higher twist corrections, as has been
surmised earlier from the nuclear target $A$-dependence of the production cross
section.


title: Polarization of Charmonium in \pi N Collisions

abstract:
  Measurements of the polarization of $\jp$ produced in pion-nucleus collisions
are in disagreement with leading twist QCD prediction where $\jp$ is observed
to have negligible polarization whereas theory predicts substantial
polarization. We argue that this discrepancy cannot be due to poorly known
structure functions nor the relative production rates of $\jp$ and $\chi_J$.
The disagreement between theory and experiment suggests important higher twist
corrections, as has earlier been surmised from the anomalous non-factorized
nuclear $A$-dependence of the $\jp$ cross section.


title:
A Dependence of Hadron Production in Inelastic Muon Scattering and
  Dimuon Production by Protons

abstract:
  The A dependence of the production of hadrons in inelastic muon scattering
and of the production of dimuons in high $Q^2$ proton interactions are simply
related. Feynman x distributions and z scaling distributions in nuclei are
compared with energy loss models. Suggestions for new data analyses are
presented.


title: Matching QCD and HQET heavy--light currents at two loops and beyond

abstract:
  Heavy--light QCD currents are matched with HQET currents at two loops and
leading order in $1/m$. A single formula applies to all current matchings. As a
by--product, a master formula for the two--loop anomalous dimension of the QCD
current $\bar{q}\gamma^{[\mu_1}\ldots\gamma^{\mu_n]}q$ is obtained, yielding a
new result for the tensor current. The dependence of matching coefficients on
$\gamma_5$ prescriptions is elucidated. Ratios of QCD matrix elements are
obtained, independently of the three--loop anomalous dimension of HQET
currents. The two--loop coefficient in $f_{{\rm B}^*}/f_{\rm B} =1-2\alpha_{\rm
s}(m_b)/3\pi-K_b\alpha_{\rm s}^2/\pi^2 +{\rm O}(\alpha_{\rm s}^3,1/m_b)$ is
\[K_b=\frac{83}{12}+\frac{4}{81}\pi^2+\frac{2}{27}\pi^2\log2-\frac19\zeta(3)
-\frac{19}{54}N_l+\Delta_c=6.37+\Delta_c\] with $N_l=4$ light flavours, and a
correction, $\Delta_c=0.18\pm0.01$, that takes account of the non--zero ratio
$m_c/m_b=0.28\pm0.03$. Fastest apparent convergence would entail $\alpha_{\rm
s}(\mu)$ at $\mu=370$~MeV. ``Naive non--abelianization'' of large--$N_l$
results, via $N_l\to N_l-\frac{33}{2}$, gives reasonable approximations to
exact two--loop results. All--order results for anomalous dimensions and
matching coefficients are obtained at large $\beta_0=11-\frac23N_l$. Consistent
cancellation between infrared-- and ultraviolet--renormalon ambiguities is
demonstrated.


title:
The Deuteron Spin Structure Functions in the Bethe-Salpeter Approach and
  the Extraction of the Neutron Structure Function $g_1^n(x)$

abstract:
  The nuclear effects in the spin-dependent structure functions $g_1^D$ and
$b_2^D$ are calculated in the relativistic approach based on the Bethe-Salpeter
equation with a realistic meson-exchange potential.
  The results of calculations are compared with the non-relativistic
calculations. The problem of extraction of the neutron spin structure function,
$g_1^n$, from the deuteron data is discussed.


title:
b \rightarrow s \gamma AND Z \rightarrow b \overline{b} IN TECHNICOLOR
  WITH SCALARS

abstract:
  We consider the radiative decay $b\rightarrow s \gamma$, and the correction
to the $Zb\overline{b}$ vertex in technicolor models with scalars. In these
models, the scalar develops a vacuum expectation value when the technifermions
condense, and the ordinary fermions develop masses via Yukawa couplings. Since
the symmetry breaking sector involves both a fundamental scalar doublet and an
isotriplet of composite scalars (the technipions), the phenomenology associated
with the charged scalars is similar to that found in a type-I two-Higgs doublet
model. We show that the correction to the $Zb\overline{b}$ vertex is small over
the allowed parameter space of the model in the two limits that we consider,
and that there can be large, potentially observable, contributions to the
$b\rightarrow s \gamma$ branching fraction.


title: Pi-Pi scattering lengths at finite temperature

abstract:
  The $s$-wave $\pi-\pi$ scattering lengths $a^I(T)$ at finite temperature $T$
and isospin $I=0,2$ are calculated within the SU(2) Nambu--Jona-Lasinio model.
$a^2(T)$ displays a singularity at the Mott temperature $T_M$, defined as
$m_\pi(T_M) = 2m_q(T_M)$, while $a^0(T)$ is singular in addition at the lower
temperature $T_d$, where $m_\sigma(T_d) = 2m_\pi(T_d)$, $m_\sigma$ and $m_\pi$
being the masses of the $\sigma$ and $\pi$ mesons, respectively. Numerically we
find $T_d = 198$MeV and $T_M=215$MeV. We speculate on possible experimental
consequences.


title:
A Simple Prescription for First Order Corrections to Quark Scattering
  and Annihilation Processes

abstract:
  We formulate the first order corrections to processes involving the
scattering or annihilation of quarks in a form in which the QCD and electroweak
parts are exactly factorised. This allows for a straightforward physical
interpretation of effects such as lepton-hadron correlations, and a simpler
Monte Carlo treatment. The postscript file for this paper can also be obtained
by anonymous ftp from thep.lu.se, in the file pub/Preprints/lu_tp_94_13.ps


title: Transition Radiation of Ultrarelativistic Neutral Particles

abstract:
  We perform a quantum theoretical calculation of transition radiation by
neutral particles with spin 1/2 equipped with magnetic moments and/or electric
dipole moments. The limit of vanishing masses is treated exactly for arbitrary
refraction index. Finally we apply our result to the solar neutrino flux.


title: Dynamical Generation of the CKM Matrix

abstract:
  We argue that in dynamical models of fermion masses, which explain the three
mass scales of the generations of fermions with three separate heavy scales
above the electroweak symmetry breaking scale, the off diagonal CKM matrix
elements must be generated at a fourth scale. The simplest form for the
additional mass generation is a mechanism that has an $SU(3)_L \otimes SU(3)_R$
family symmetry. We show that such an ansatz can produce the up down mass
inversion and the observed Cabibbo angle. If the mass terms for the third
family quarks are enhanced by additional interactions the full CKM matrix may
be realized. We present a toy model which realizes vacua with these masses.}


title:
On the consistent solution of the gap--equation for spontaneously broken
  $\lambda \Phi^4$-theory

abstract:
  We present a self--consistent solution of the finite temperature
gap--equation for $\lambda \Phi^4$ theory beyond the Hartree-Fock approximation
using a composite operator effective action. We find that in a spontaneously
broken theory not only the so--called daisy and superdaisy graphs contribute to
the resummed mass, but also resummed non--local diagrams are of the same order,
thus altering the effective mass for small values of the latter.


title:
The Analytical Value of the Corner-Ladder Graphs Contribution to the
  Electron G-2 in QED

abstract:
  The contributions to the (g-2) of the electron from the corner-ladder graphs
in sixth-order (three-loop) QED perturbation theory are evaluated in closed
analytical form. The results obtained are in excellent agreement with the most
precise numerical evaluations already existing in the literature. Our results
allows one to reduce the numerical uncertainty of the theoretical determination
of the g-2 of the electron.


title: Relativistic Flux Tube Model Calculation of the Isgur-Wise Function

abstract:
  The Relativistic Flux Tube model is used to calculate of the Isgur-Wise
functions describing the exclusive semileptonic decays of $\bar{B}$ and
$\bar{B}_{s}$ mesons. The light quark mass dependence is investigated and the
predicted universal function agrees well with the results of lattice
simulations, and with the experimental data. Recent experimental measurements
of the $\bar{B}\ra D^{*}l\bar{\nu}_{l}$ decay distribution yield the CKM
element $V_{bc}=0.035\pm 0.001$. The IW function slope and second derivative at
the zero recoil point are predicted to be $\xi'(1) = -0.93\pm 0.04$ and
$\xi''(1)= 1.7\pm 0.1$ for a range of light quark massses. The importance of
including higher derivatives in analyses of experiment is emphasized.


title: The Two Pomerons

abstract:
  A wide variety of experimental data in hadronic reactions are described in
terms of the exchange of an object called the soft pomeron. It is
nonperturbative in origin and is perhaps associated with glueballs. The HERA
measurements of $\nu W_2$ at small $x$ suggest the possibility that there is
also a hard pomeron, which is perturbative. I review the experimental and
theoretical methods that are used to explore the two pomerons and emphasise the
problems that remain to be solved.


title: Radiative Corrections for Pion Polarizability Experiments

abstract:
  We use the semi-analytical program RCFORGV to evaluate radiative corrections
to one-photon radiative emission in the high-energy scattering of pions in the
Coulomb field of a nucleus with atomic number Z. It is shown that radiative
corrections can simulate a pion polarizability effect. The average effect was
estimated for pion energies 40-600 GeV. We also study the range of
applicability of the equivalent photon approximation in describing one-photon
radiative emission.


title:
Hadronic contributions to the anomalous magnetic moment of the muon by
  QCD model with infinite number of vector mesons

abstract:
  We computed the hadronic vacuum-polarization contributions to the muon
anomalous magnetic moment $a_{\mu}(hadr.)$ by using the QCD model with infinite
number of vector mesons [1,2]. The result is $a_{\mu}(hadr.) = 663(23) \times
10^{-10}$. }


title:
CP Violation in the Decay $b\rightarrow s\gamma$ in the Two-Higgs
  Doublet Model

abstract:
  In the most general two-Higgs doublet model with an approximate family
symmetry and CP violation being originated solely from the relative phase of
two vacuum expectation values, CP asymmetry in the decay $b\rightarrow s\gamma$
may arise from the CP violation of the charged Higgs boson interactions with
fermions. This asymmetry may be larger than in the standard model and can lie
between $10^{-2}$ and $10^{-1}$. The decay rate of $b\rightarrow s\gamma$ is
allowed to be smaller or larger than in the standard model