title: Direct Photoproduction of Jets in the KT Factorisation Prescription

abstract:
  We study the cross section for dijet production via direct photons, as seen
at the HERA collider. Rather than assuming the standard factorisation formula
for the cross section (where the incoming partons are assumed to be on-shell),
we use the $k_T$-factorisation formula. This formalism ought to be more
appropriate for jet production in regions where the cross section is sensitive
to the small-$x$ parton distribution functions. We study the rapidity
distribution and the azimuthal angular distribution of the jets and compare
with the traditional approach. Our calculations reveal a breakdown of the
traditional approach as one moves into the regime of small $x$.


title:
Gravitino Production in the Inflationary Universe and the Effects on
  Big-Bang Nucleosynthesis

abstract:
  Gravitino production and decay in the inflationary universe are reexamined.
Assuming that the gravitino mainly decays into a photon and a photino, we
calculate the upperbound on the reheating temperature. Compared to previous
works, we have essentially improved the following two points: (i) the helicity
$\pm\frac{3}{2}$ gravitino production cross sections are calculated by using
the full relevant terms in the supergravity lagrangian, and (ii) the high
energy photon spectrum is obtained by solving the Boltzmann equations
numerically. Photo-dissociation of the light elements (D, T, $^3$He, $^4$He)
leads to the most stringent upperbound on the reheating temperature, which is
given by ($10^{6}$--$10^{9}$)GeV for the gravitino mass 100GeV--1TeV. On the
other hand, requiring that the present mass density of photino should be
smaller than the critical density, we find that the reheating temperature have
to be smaller than ($10^{11}$--$10^{12}$)GeV for the photino mass (10--100)GeV,
irrespectively of the gravitino mass. The effect of other decay channels is
also considered.


title:
Semi Hard Parton Rescatterings in Nuclear Collisions at Very High
  Energies

abstract:
  Representing the semi-hard partonic interactions by the exchange of Lipatov's
perturbative Pomeron, we express the semi-hard nuclear cross section as a self
shadowing cross section. With the help of a generating functional technique, we
obtain average numbers of multiple semi-hard partonic collisions without any
need of using explicit expressions for the multi-parton distributions. The
average number of semi-hard interactions of a given projectile parton against a
target nucleus is estimated quantitatively and it is shown to grow very rapidly
above one with increasing the c.m. energy. (Figures available on request)


title: V-a Tests Through Leptons from Polarised Top Quarks

abstract:
  Angular-energy distributions are studied for charged leptons and neutrinos
from the decays of polarised top quarks. A small admixture of V+A interactions
is incorporated. The polarisation dependent part of the neutrino distribution
which can be measured experimentally through the missing momentum is
particularly sensitive towards deviations from the V-A structure. This result
remains unaffected by QCD corrections which, however, cannot be neglected in a
quantitative analysis.


title: Phase structure of $SU(2)$ Yang-Mills theory with global center symmetry

abstract:
  Retaining only the `timelike' component $A_0$ of the vector potential a
skelet model with explicit global center symmetry is constructed for $SU(2)$
Yang-Mills theory. It is shown that the $A_0$ gluon vacuum is equivalent with
the 4-dimensional Coulomb-gas. In 1--loop approximation, the effective theory
of the skelet model exhibits non-local self-interaction. A coupling constant
$\lambda$ is found that governs the loop expansion. For $\lambda < 1$ the
effective theory does not confine (the string tension vanishes), whereas for
$\lambda = 1$ confinement (with non-vanishing string tension) takes place. In
the deconfined phase the $A_0$ gluons exhibit non-zero rest mass and global
center symmetry is broken by the vacuum state.
  Confinement sets on for $\lambda =1$ when the rest mass of $A_0$ gluons
vanishes and the global center symmetry of the vacuum is restored.


title: $\gamma \gamma $ Processes at High Energy pp Colliders

abstract:
  In this note we investigate the production of charged heavy particles via
\gaga\ fusion at high energy pp colliders. We revise previous claims that the
\gaga\ cross section is comparable to or larger than that for the corresponding
Drell-Yan process at high energies. Indeed we find that the \gaga\ contribution
to the total production cross section at pp is far below the Drell-Yan cross
section. As far as the individual elastic, semi-elastic and inelastic
contributions to the \gaga\ process are concerned we find that they are all of
the same order of magnitude.


title:
Deficiency of the Gross - Llewellyn Smith Sum Rule and QCD Vacuum
  Polarization Effect

abstract:
  From the analysis of the recent CCFR data for the \st\ $xF_3(x,Q^2)$
($0.015<x<0.65$ and $1.2\ GeV^2 < |Q^2| < 501\ GeV^2$) of the deep inelastic
neutrino - nucleon scattering we conclude that probably part of the nucleon
baryon number is due to the vacuum polarization effects.


title: $B \rar K^* \ \gamma$} from Hybrid Sum Rule

abstract:
  Using the {\it hybrid} moments-Laplace sum rule (HSR), which is well-defined
for $M_b \rar \infty$, in contrast with the $popular$ double Borel (Laplace)
sum rule (DLSR), which blows up in this limit when applied to the
heavy-to-light processes, we show that the form factor of the $B \rar K^* \
\gamma$ radiative transition is dominated by the light-quark condensate for
$M_b \rar \infty$ and behaves like $\sqrt M_b$. The form factor is found to be
$ F^{B\rar K^*}_1(0) \simeq (30.8 \pm 1.3 \pm 3.6 \pm 0.6)\times 10^{-2}, $
where the errors come respectively from the procedure in the sum rule analysis,
the errors in the input and in the $SU(3)_f$-breaking parameters. This result
leads to $Br(B\rar K^* \ \gamma) \simeq (4.45 \pm 1.12) \times 10^{-5}$ in
agreement with the recent CLEO data. Parametrization of the $M_b$-dependence of
the form factor including the $SU(3)_f$-breaking effects is given in (26),
which leads to $F^{B\rar K^*}_1(0)/ F^{B\rar \rho}_1(0) \simeq (1.14 \pm
0.02)$.


title:
Calculation of Chirality Violating Proton Structure Function h$_1$(x) in
  QCD

abstract:
  The twist-two chirality violating proton structure function $h_1(x)$
measurable in the polarized Drell-Yan process is calculated by means of QCD sum
rules at intermediate $x$, $0.3 < x < 0.7$ and $Q^2 \approx 5-10 GeV^2$.


title: Heavy Meson Decays into Light Resonances

abstract:
  We analyse the Lorentz structures of weak decay matrix elements bewteen meson
states of arbitrary spin. Simplifications arise in the transition amplitudes
for a heavy meson decaying into a light one via a Bethe-Salpeter approach which
incorporates heavy quark symmetry. Phenomenological consequences on several
semileptonic, nonleptonic and FCNC induced decays of heavy flavoured mesons are
derived and discussed.


title:
$Z^0$--${Z^0}^\prime$ and ordinary-exotic fermion mixings revisited
  using some special observables

abstract:
  We investigate the mixing of an extra ${Z^0}^\prime$ with the standard $Z^0$
and mixings of exotic fermions with their standard counterparts through some
precisely measured electroweak observables. These observables are geared to
search for physics beyond the Standard Model. We observe that although most of
such mixings are severely constrained by the recent LEP data, some of the
mixing angles could still be rather large, awaiting future tests.


title:
Coherent state formulation of pion radiation from nucleon antinucleon
  annihilation

abstract:
  We assume that nucleon antinucleon annihilation is a fast process leading to
a classical coherent pion pulse. We develop the quantum description of such
pion waves based on the method of coherent states. We study the consequences of
such a description for averages of charge types and moments of distributions of
pion momenta with iso-spin and four-momentum conservation taken into account.
We briefly discuss the applicability of our method to annihilation at rest,
where we find agreement with experiment, and suggest other avenues for its use.


title: Massless Scalar QED with Non-minimal Chern Simons Coupling

abstract:
  2+1 dimensional massless scalar QED with $(\phi^*\phi)^3$ scalar
self-coupling is modified by the addition of a non- minimal Chern-Simons term
that couples the dual of the electromagnetic field strength to the covariant
current of the complex scalar field. The theory is shown to be fully one- loop
renormalizable. The one loop effective potential for the scalar field gives
rise to spontaneous symmetry breaking which induces masses for both the scalar
and vector fields. At high temperature there is a symmetry restoring phase
transition.


title:
The Inclusive $\bar B\to \tau \bar\nu X$ Decay in Two Higgs Doublet
  Models

abstract:
  We calculate in the framework of two Higgs doublet models the differential
decay rate for inclusive $\bar B\to\tau\,\bar\nu\,X$ transitions to order
$1/m_b^2$ in the heavy quark expansion, for both polarized and unpolarized tau
leptons. In contrast to the situation in the standard model, we find sizeable
$1/m_b^2$ corrections. A systematic heavy quark expansion significantly reduces
the theoretical uncertainties in the calculation compared to the existing free
quark decay model results. From the experimental measurement of the branching
ratio, we derive the bound $\tan\beta < 0.51\, m_{H^\pm}\,[{\rm GeV}]$. We
point out that the tau polarization is potentially a more sensitive probe of
multi scalar models than the branching ratio itself.


title:
The $A_{LL}$ asymmetry in diffractive reactions and structure of
  quark-pomeron vertex

abstract:
  Theoretical predictions for the behavior of $A_{LL}$ asymmetry determined by
the pomeron-hadron vertex are done. Strong dependence of the asymmetry on the
mass creating quarks and transfer momenta is shown.


title:
Renormalizable W Self-Energy in the Unitary Gauge via the Pinch
  Technique

abstract:
  We use the S-matrix pinch technique to derive to one loop order an effective
renormalizable self-energy for the W gauge boson, when the theory is quantized
in the unitary gauge. We then show that this amplitude is identical to the
$\xi$-independent W self-energy previously constructed by applying the pinch
technique in the context of the renormalizable $R_{\xi}$ gauges.}


title: Two-Photon Production of Charged Pion and Kaon Pairs

abstract:
  A measurement of the cross section for the combined two-photon production of
charged pion and kaon pairs is performed using 1.2~$\rm fb^{-1}$ of data
collected by the CLEO~II detector at the Cornell Electron Storage Ring. The
cross section is measured at invariant masses of the two-photon system between
1.5 and 5.0 GeV/$c^2$, and at scattering angles more than $53^\circ$ away from
the $\gamma\gamma$ collision axis in the $\gamma\gamma$ center-of-mass frame.
The large background of leptonic events is suppressed by utilizing the CsI
calorimeter in conjunction with the muon chamber system. The reported cross
section is compared with leading order QCD models as well as previous
experiments. In particular, although the functional dependence of the measured
cross section disagrees with leading order QCD at small values of the
two-photon invariant mass, the data show a transition to perturbative behavior
at an invariant mass of approximately 2.5 GeV/$c^2$. hardcopies with figures
can be obtained by writing to to: Pam Morehouse preprint secretary Newman Lab
Cornell University Ithaca, NY 14853 or by sending mail to:
preprints@lns62.lns.cornell.edu


title: Pi- Eta Mixing from QCD Sum Rules

abstract:
  The $q^2$ dependence of the $\pi$-$\eta$ mixing amplitude is examined with
the use of QCD sum rules. The linear slope of the mixing function $\theta(q^2)$
is found to be much smaller than that for $\rho$-$\omega$ mixing. Thus the
mixing amplitude is approximately the same in the space-like region as in the
time-like one, and one may neglect the $q^2$ dependence of the mixing. A
comparison between a hadron-meson, an effective chiral model, and the QCD sum
rules approaches is made.


title: The Instanton Density at Finite Temperatures

abstract:
  For {\it low} T new strict results for the instanton density n(T) are
reported. Using the PCAC methods, we express n(T) in terms of {\it vacuum}
average values of certain operators, times their {\it calculated} T-dependence.
At high T, we discuss the {\it applicability} limits of the perturbative
results. We further speculate about possible behaviour of n(T) at $T\sim T_c$.


title: Measurement of the Branching Fraction for D^+ \to K^- \pi^+ \pi^+

abstract:
  Using the CLEO-II detector at CESR we have measured the ratio of branching
fractions, ${\cal B}(D^+\rightarrow K^- \pi^+ \pi^+)/{\cal B}(D^0 \rightarrow
K^-\pi^+) = 2.35 \pm 0.16 \pm 0.16$. Our recent measurement of ${\cal B}(D^0
\rightarrow K^-\pi^+)$ then gives ${\cal B}(D^+\rightarrow K^- \pi^+ \pi^+) =
(9.3 \pm 0.6 \pm 0.8)\%$.


title: The next-to-leading QCD approximation to the Ellis-Jaffe sum rule

abstract:
  The \alpha_s^2 correction to the Ellis-Jaffe sum rule for the structure
function g_1 of polarized deep inelastic lepton-nucleon scattering is
calculated.


title:
Waiting for the Top Quark Mass, K^+ --> \pi^+ \nu \bar\nu,
  B_s^0-\bar{B}_s^0 Mixing and CP Asymmetries in B-Decays

abstract:
  Anticipating improved determinations of m_t, |V_ub/V_cb|, B_K and F_B
\sqrt{B_B} in the next five years we make an excursion in the future in order
to find a possible picture of the unitarity triangle, of quark mixing and of
CP-violation around the year 2000. We then analyse what impact on this picture
will have the measurements of four possibly cleanest quantities: BR(K^+ -->
\pi^+ \nu \bar\nu), x_d/x_s, sin(2\alpha) and \sin(2\beta). Our analysis shows
very clearly that there is an exciting time ahead of us. In the course of our
investigations we extend the analysis of the unitarity triangle beyond the
leading order in \lambda and we derive several useful analytic formulae for
quantities of interest.


title:
Short and Long Distance Effects in the Decay $\tau \to \pi \nu_\tau
  (\gamma)$

abstract:
  We calculate the radiative corrections to the decays $\tau\to M \nu_\tau$ and
$\pi \to l \nu_\l$, where the meson $M$ is $M=\pi$ or $K$ and the lepton $l$ is
$l = e$ or $\mu$. We perform a complete calculation, which includes internal
bremsstrahlung and structure dependent radiation in the radiative decays and
point meson, hadronic structure dependent and short distance contributions in
the virtual corrections. Our result for the radiative correction to the ratio
$\Gamma(\tau\to\pi\nu_\tau(\gamma))/ \Gamma(\pi\to\mu\nu_\mu(\gamma))$ is
$\delta R_{\tau/\pi} = \left(0.16_{\T - 0.14}^{\T+0.09}\right) \%$. For the
ratio $\Gamma(\tau\to K\nu_\tau(\gamma)) / \Gamma(K\to \mu\nu_\mu(\gamma))$, we
obtain $\delta R_{\tau/K } = \left(0.90_{\T - 0.26}^{\T + 0.17}\right) \%$. For
completeness we have also calculated the ratio of the electronic and muonic
decay modes of the pion.


title:
Dependence of Electroweak Parameters on the Definition of the Top-Quark
  Mass

abstract:
  The QCD corrections to electroweak parameters depend on the renormalization
scheme and scales used to define the top-quark mass. We analyze these
dependences for the W-boson mass predicted via Delta r to O(alpha alpha_s) and
O(alpha alpha_s^2) in the on-shell and MS-bar schemes. These variations provide
us with a hint on the magnitude of the unknown higher-order QCD effects and
contribute to the theoretical error of the prediction.


title: Quarkonium production and decays

abstract:
  Quarkonium decays are studied in the charmonium model. Relativistic
corrections, higher-order perturbative QCD corrections and non- perturbative
contributions are discussed. Recent measurements of charmonium annihilation
rates are used to evaluate the strong coupling constant $\alpha_s$
simultaneously with the wave functions (and their derivatives) at the origin.
Further predictions are made for yet unobserved decay rates. The various models
for quarkonium production in hadronic collisions are critically reviewed. Based
on the charmonium model, the cross sections of different quarkonium states are
given in a well-defined QCD perturbation series, including quark--antiquark,
quark--gluon, and gluon--gluon scatterings. Numerical estimates are given for
charmonium production in $\p\p$, $\ppbar$, and $\pi\p$ collisions. The role of
indirect $\JP$ production via $\chi_{\c J}(1P)$, $\eta_{\c}(2S)$, $\psi(2S)$
and $\b$-decays is pointed out. Relativistic effects and non-perturbative
contributions are found to be important. Existing measurements are compiled and
shown to be well explained if all contributions are included. The ${}^1S_0$
cross section is calculated in complete next-to-leading order. Finally, a study
of the high-energy behaviour of quarkonium cross sections is made, based on the
asymptotical behaviour of higher-order QCD corrections.


title: Confinement in Three Dimensions and the Electroweak Phase Transition

abstract:
  The infrared behaviour of the standard model at finite temperature is
determined by the confining phase of the SU(2)-Higgs model in three dimensions.
Due to the Landau singularity of the three-dimensional gauge theory the
perturbative treatment of the electroweak phase transition breaks down for
Higgs masses above a critical mass $m_H^c$. Based on a renormalization group
improved effective potential we find $m_H^c\sim$ 70 GeV. The scalar
self-coupling has a Landau-type singularity also in the abelian U(1)-Higgs
model, which leads to a breakdown of perturbation theory in the symmetric
phase.


title: CP violating polarizations in semileptonic heavy meson decays

abstract:
  We study the $T$-violating lepton transverse polarization ($P^\perp_l$) in
three body semileptonic heavy meson decays to pseudoscalar mesons and to vector
mesons. We calculate these polarizations in the heavy quark effective limit,
which simplifies the expressions considerably. After examining constraints from
$CP$ conserving (including $b \rightarrow s \gamma$) and $CP$ violating
processes, we find that in $B$ decays, $P^\perp$ of the muon in multi-Higgs
doublet models can be of order $10\%$, while $P^\perp$ of the $\tau$ can even
approach unity. In contrast, $P^\perp_\mu$ in $D$ decays is at most 1.5\%. We
discuss possibilities for detection of $P^\perp_l$ at current and future $B$
factories. We also show that $P^\perp_l$ in decays to vector mesons, unlike in
decays to pseudoscalars, can get contributions from left-right models.
Unfortunately, $P^\perp_l$ in that case is proportional to $W_L$-$W_R$ mixing,
and is thus small.


title: $K_{l4}$ - Decays Beyond One Loop

abstract:
  The matrix elements for $K\rightarrow \pi \pi \l \nu$ decays are described by
four form factors $F,G,H$ and $R$. We complete previous calculations by
evaluating $R$ at next-to-leading order in the low-energy expansion. We then
estimate higher order contributions using dispersion relations and determine
the low-energy constants $L_1,L_2$ and $L_3$ from data on $K_{e4}$ decays and
on elastic pion scattering. Finally, we present predictions for the slope of
the form factor $G$ and for total decay rates.


title: Gauge Invariant Treatment of the Electroweak Phase Transition

abstract:
  We evaluate the gauge invariant effective potential for the composite field
$\sigma=2\Phi^{\dagger}\Phi$ in the SU(2)-Higgs model at finite temperature.
Symmetric and broken phases correspond to the domains $\sigma\leq T^2/3$ and
$\sigma > T^2/3$, respectively. The effective potential increases very steeply
at small values of $\sigma$. Predictions for several observables, derived from
the ordinary and the gauge invariant effective potential, are compared. Good
agreement is found for the critical temperature and the jump in the order
parameter. The results for the latent heat differ significantly for large Higgs
masses.


title: On Axially Symmetric Solutions in the Electroweak Theory

abstract:
  We present the general ansatz, the energy density and the Chern-Simons charge
for static axially symmetric configurations in the bosonic sector of the
electroweak theory. Containing the sphaleron, the multisphalerons and the
sphaleron-antisphaleron pair at finite mixing angle, the ansatz further allows
the construction of the sphaleron and multisphaleron barriers and of the
bisphalerons at finite mixing angle. We conjecture that further solutions
exist.


title: gamma-gamma and gamma-p Events at High Energies

abstract:
  A real photon has a complicated nature, whereby it may remain unresolved or
fluctuate into a vector meson or a perturbative q-qbar pair. Based on this
picture, we previously presented a model for gamma-p events that is based on
the presence of three main event classes: direct, VMD and anomalous. In
gamma-gamma events, a natural generalization gives three-by-three combinations
of the nature of the two incoming photons, and thus six distinct event classes.
The properties of these classes are constrained by the choices already made, in
the gamma-p model, of cut-off procedures and other aspects. It is therefore
possible to predict the energy-dependence of the cross section for each of the
six components separately. The total cross section thus obtained is in good
agreement with data, and also gives support to the idea that a simple
factorized ansatz with a pomeron and a reggeon term can be a good
approximation. Event properties undergo a logical evolution from p-p to gamma-p
to gamma-gamma events, with larger charged multiplicity, more transverse energy
flow and a higher jet rate in the latter process.


title: Colour Correlations and Multiplicities in Top Events

abstract:
  In events of the type e+ e- -> t tbar -> b W+ bbar W-, particle production
could depend in a non-trivial way on the kinematics of the process. Energetic
perturbative gluon radiation can be generated (when kinematically allowed) by
the original t tbar system and by the t -> b W+ and tbar -> bbar W- decays,
with negligible interference between the production and decay stages and
between the t and tbar decays. Soft perturbative gluon emission and
non-perturbative fragmentation does introduce a correlation, however. To
illustrate the size of these effects, we study the multiplicity as a function
of the angle between the b and bbar jets, close to the t tbar threshold. Also
potential uncertainties in top mass determinations are briefly addressed.


title: Cosmic Rays From Cosmic Strings

abstract:
  It has been speculated that cosmic string networks could produce ultra-high
energy cosmic rays as a by-product of their evolution. By making use of recent
work on the evolution of such networks, it will be shown that the flux of
cosmic rays from cosmologically useful, that is GUT scale strings, is too small
to be used as a test for strings with any foreseeable technology.


title: J/Psi Production from Electromagnetic Fragmentation in Z decay

abstract:
  The rate for $ Z^{0}\to J/ \psi + \ell^{+}\ell^{-} $ is suprisingly large
with about one event for every million $Z^{0}$ decays. The reason for this is
that there is a fragmentation contribution that is not suppressed by a factor
of $M^{2}_{\psi}/M^{2}_{Z}$. In the fragmentation limit $ M_{Z}\to\infty$ with
$E_{\psi}/M_{Z}$ fixed, the differential decay rate for $ Z^{0}\to J/ \psi +
\ell^{+}\ell^{-} $ factors into electromagnetic decay rates and universal
fragmentation functions. The fragmentation functions for lepton fragmentation
and photon fragmentation into $J/\psi$ are calculated to lowest order in
$\alpha$. The fragmentation approximation to the rate is shown to match the
full calculation for $E_{\psi}$ greater than about $3 M_{\psi}$.


title: Supersymmetric predictions for the inclusive $b\to s\gamma$ decay

abstract:
  We study the penguin induced transition $b\to s\ \gamma$ in the minimal N=1
supersymmetric extension of the Standard Model with radiative breaking of the
electroweak group. We include the effects of one-loop corrections to the Higgs
potential and scalar masses. We show that the present upper and lower
experimental limits on the inclusive decay sharply constrain the parameter
space of the model in a wide range of $\tan\beta$ values. The implications of
the recently advocated relation $|B|\ge 2$ for the bilinear SUSY soft breaking
parameter in grand unified theories are also analyzed.


title: Flavour-Violating Charged Lepton Decays in Seesaw-Type Models

abstract:
  Analytic expressions of lepton-flavour- and lepton-number-violating decays of
charged leptons are derived in the context of general $SU(2)_L\otimes U(1)_Y$
seesaw scenarios that are motivated by grand unified theories (GUT's) or
superstring models, in which left-handed and/or right-handed neutral singlets
are present. Possible constraints imposed by cosmology and low-energy data are
briefly discussed. The violation of the decoupling theorem in flavour-dependent
graphs due to the presence of heavy neutral leptons of Dirac or Majorana nature
is emphasized. Numerical estimates reveal that the decays $\tau^-\to e^-e^-e^+$
or $\tau^-\to e^-\mu^-\mu^+$ can be as large as $\sim 10^{-6}$, which may be
observed in LEP experiments or other $\tau$ factories.


title: Gauge invariance of massless QED

abstract:
  A simple general proof of gauge invariance in QED is given in the framework
of causal perturbation theory. It illustrates a method which can also be used
in non-abelian gauge theories.


title:
Rigourous QCD Evaluation of Spectrum and Other Properties of Heavy
  Quarkonium Systems; II Bottomium with n=2, l=0,1

abstract:
  We calculate the Lamb, fine and hyperfine shifts in $b\bar b$ with $n=2$,
$l=0,1$. Radiative corrections as well as leading nonperturbative corrections
(known to be due to the gluon condensate) are taken into account. The
calculation is parameter-free, as we take $\Lambda$, ${\langle \alpha_s G^2
\rangle}$ from independent sources. Agreement with experiment is found at the
expected level $\sim 30\%$. Particularly interesting is a prediction for the
hyperfine splitting, $M_{\rm average}(2^3P)-M(2^1P_1) = 1.7 \pm 0.9\, {\rm
MeV}$, opposite in sign to the $c\bar c$ one ($\approx -0.9\, {\rm MeV}$), and
where the nonzero value of ${\langle \alpha_s G^2 \rangle}$ plays a leading
role.


title: Gluon Fragmentation into P-wave Heavy Quarkonium

abstract:
  The fragmentation functions for gluons to split into P-wave heavy quarkonium
states are calculated to leading order in the QCD coupling constant.
Long-distance effects are factored into two nonperturbative parameters: the
derivative of the radial wavefunction at the origin and a second parameter
related to the probability for a heavy-quark-antiquark pair that is produced in
a color-octet S-wave state to form a color-singlet P-wave bound state. The
fragmentation probabilities for a high transverse momentum gluon to split into
the P-wave charmonium states $\chi_{c0}$, $\chi_{c1}$, and $\chi_{c2}$ are
estimated to be $0.4 \times 10^{-4}$, $1.8 \times 10^{-4}$, and $2.4 \times
10^{-4}$, respectively. This fragmentation process may account for a
significant fraction of the rate for the inclusive production of $\chi_{cJ}$ at
large transverse momentum in $p \bar p$ colliders.


title: Structure of the Chiral Scalar Superfield in Ten Dimensions

abstract:
  We describe the tensors and spinor-tensors included in the $\theta$-expansion
of the ten-dimensional chiral scalar superfield. The product decompositions of
all the irreducible structures with $\theta$ and the $\theta^2$ tensor are
provided as a first step towards the obtention of a full tensor calculus for
the superfield.


title: Deriving the Hard Thermal Loops of QCD from Classical Transport Theory

abstract:
  Classical transport theory is employed to analyze the hot quark-gluon plasma
at the leading order in the coupling constant. A condition on the (covariantly
conserved) color current is obtained. {}From this condition, the generating
functional of hard thermal loops with an arbitrary number of soft external
bosonic legs can be derived. Our approach, besides being more direct than
alternative ones, shows that hard thermal loops are essentially classical.


title:
Structural Vertices of Extended SU(3)-Chiral Lagrangians in the
  Large-N_c Approach

abstract:
  The main goal of this paper is to elaborate the model-framework
parametrization of effective coupling constants of the extended chiral
lagrangian which is suitable for the description of the low-energy matrix
elements of vector, axial-vector, scalar and pseudoscalar currents as well as
of the matrix elements of the pseudoscalar gluon density. We establish the
connection between the structural coupling constants of the phenomenological
chiral lagrangian and the coefficients of effective lagrangians obtained in the
QCD-bosonization models by means of the derivative expansion. The large-N_c
relations for corresponding structural constants are elaborated. On this way we
find the new set of OZI rules. In particular, one of them predicts the
branching ratio of the decays $\psi' \rightarrow J/\psi + \pi$ or $\eta$.


title: Isospin Symmetry Breaking in Hadrons and Nuclei

abstract:
  A brief review of the isospin symmetry breaking in hadrons and nuclei is
given with emphasis on the $u-d$ quark mass difference. The off-shell
$\rho^0-\omega$ mixing is studied as a typical example of the symmetry
breaking, and its relevance to the nuclear force and nuclei is discussed.


title:
Electroweak Radiative Corrections, Born Approximation, and Precision
  Tests of the Standard Model at LEP

abstract:
  We have examined the evidence for the electroweak radiative corrections in
the LEP precision data along with the intriguing possibility that the QED
corrections only may be sufficient to fit the data. We find that the situation
is very sensitive to the precise value of $M_W$. While the world average value
of $M_W$ strongly favors nonvanishing electroweak radiative corrections, the
QED corrections alone can account for the data within $2\sigma $ in the context
of the standard model. We discuss how the precision measurements of $M_W$ can
provide a decisive test for the standard model with radiative corrections and
give a profound implication for the existence of t-quark and Higgs scalar.


title: The Mass Definition in Hqet and a New Determination of V$_{\text{cb}}$

abstract:
  Positive powers of the mass parameter in a physical quantity calculated with
the help of heavy quark effective theory originate from a Wilson coefficient in
the matching of QCD and HQET Green function. We show that this mass parameter
enters the calculation as a well--defined running current mass. We further
argue that the recently found ill--definition of the pole mass, which is the
natural expansion parameter of HQET, does not affect a phenomenological
analysis which uses truncated perturbative series. We reanalyse inclusive
semileptonic decays of heavy mesons and obtain the $c$ quark mass
$m_c^{\overline{\text{MS}}}(m_c) = (1.35\pm 0.20)\,\text{GeV}$ where the error
is almost entirely due to scale--uncertainties. We also obtain
$m_b^{\overline{\text{MS}}}(m_b) = (4.6\pm 0.3)\,\text{GeV}$ and
$|V_{cb}|(\tau_B/1.49\,\text{ps})^{1/2} = 0.036\pm 0.005$ where the errors come
from the uncertainty in the kinetic energy of the heavy quark inside the meson,
in the experimental branching ratios, in QCD input parameters, and
scale--uncertainties.


title:
Comment on Transverse Mass Dependence of Partonic Dilepton Production in
  Ultra-Relativistic Heavy Ion Collisions

abstract:
  Comment on scale breaking effects in dilepton emission from partons during
the early stage of ultra-relativistic heavy ion collisions


title:
Analytic Solutions of QCD Evolution Equations for Parton Cascades Inside
  Nuclear Matter at Small X

abstract:
  An analytical method is presented to solve generalized QCD evolution
equations for the time development of parton cascades in a nuclear environment.
Closed solutions for the spectra of produced partons with respect to the
variables time, longitudinal momentum and virtuality are obtained under some
idealizing assumptions about the composition of the nuclear medium. Several
characteristic features of the resulting parton distributions are discussed.
One of the main conclusions is that the evolution of a parton shower in medium
is dilated as compared to free space and is accompanied by an enhancement of
particle production. These effects become stronger with increasing nuclear
density.


title: Jet Production in Polarized Lepton-Hadron Scattering

abstract:
  We calculate exact analytical expressions for \oas 3-jet and \oasz \\ 4-jet
cross sections in polarized deep inelastic lepton nucleon scattering.
Introducing an invariant jet definition scheme, we present differential
distributions of 3- and 4-jet cross sections in the basic kinematical variables
$x$ and $W^2$ as well as total jet cross sections and show their dependence on
the chosen spin-dependent (polarized) parton distributions. Noticebly
differences in the predictions are found for the two extreme choices, i.e. a
large negative sea-quark density or a large positive gluon density. Therefore,
it may be possible to discriminate between different parametrizations of
polarized parton densities, and hence between the different physical pictures
of the proton spin underlying these parametrizations.


title: Physics Beyond the Standard Model

abstract:
  In these lectures I describe some of the open questions in the standard model
relating to the nature and origin of mass, forces and matter and discuss some
of the speculative theoretical ideas put forth in this regard. Some of the
topics touched upon include supsersymmetry, dynamical symmetry breaking,
composite models, grand unified theories and superstrings.


title: 3D Physics and the Electroweak Phase Transition: Perturbation Theory

abstract:
  We develop a method for the construction of the effective potential at high
temperatures based on the effective field theory approach and renormalization
group. It allows one to sum up the leading logarithms in all orders of
perturbation theory. The method reproduces the known one-loop and two-loop
results in a very simple and economic way and clarifies the issue of the
convergence of the perturbation theory. We also discuss the assumptions being
made for the determination of the critical temperature of the electroweak phase
transition, and analyse different perturbative uncertainties in its
determination. These results are then used for the non-perturbative lattice
Monte Carlo simulations of the EW phase transition in forthcoming paper.


title: Clan Properties in Parton Showers

abstract:
  By considering clans as genuine elementary subprocesses, i.e., intermediate
parton sources in the Simplified Parton Shower model, a generalized version of
this model is defined. It predicts analytically clan properties at parton level
in agreement with the general trends observed experimentally at hadronic level
and in Monte Carlo simulations both at partonic and hadronic level. In
particular the model shows a linear rising in rapidity of the average number of
clans at fixed energy of the initial parton and its subsequent bending for
rapidity intervals at the border of phase space, and approximate energy
independence of the average number of clans in fixed rapidity intervals. The
energy independence becomes stricter by properly normalizing the average number
of clans.


title: Hyperspherical Integration and the Triple-Cross Vertex Graphs

abstract:
  We have extended the hyperspherical variables method to the analytical
calculation of the angular integral of the box graph. We discuss the
applications of our results to the analytical calculation of the QED
contribution to the electron g-2 of the set of three-loop triple-cross vertex
graphs.


title:
Analytical and Numerical Contributions of Some Tenth-Order Graphs
  Containing Vacuum Polarization Insertions to the Muon (G-2) in QED

abstract:
  The contributions to the g-2 of the muon from some tenth-order (five-loop)
graphs containing one-loop and two-loop vacuum polarization insertions have
been evaluated analytically in QED perturbation theory, expanding the results
in the ratio of the electron to muon mass (m_e /m_\mu). Some results contain
also terms known only in numerical form. Our results agree with the
renormalization group results already existing in the literature.


title: Understanding the Standard Model

abstract:
  We explore to what extent the various assumptions behind the standard model
as well as the observed quantization of electric charges of quarks and leptons
can be understood using the Adler-Bell-Jackiw anomalies. The effect of
including a non-zero neutrino mass on these considerations is also discussed.


title:
Chiral Symmetry and the Constituent Quark Model: A Null-Plane Point of
  View

abstract:
  In order to clarify the connection between {\it current} and {\it
constituent} quarks (of u,d,s flavors), several authors have used the lightlike
chiral $SU(3)\otimes SU(3)$ algebra as a central concept. This literature is
reviewed here with the goal of offering an introduction to the subject within a
convenient, unified framework. It is shown that the null-plane Hamiltonian for
free massive fermions is chirally symmetric, provided only that the particles
have equal masses ($SU(3)$ limit). In the free quark model, hadrons can be
classified by a chiral $SU(3)\otimes SU(3)$ algebra, the generators of which
are current lightlike charges. Naturally, QCD interactions break chiral
symmetry, and the axial nonsinglet charges are not conserved. This remains true
in the 'chiral limit' (zero quark masses), signalling the spontaneous breakdown
of chiral symmetry. The actual generators of the $SU(3)\otimes SU(3)$
classification of physical hadrons are obtained from the current charges by
means of a unitary transformation. Under this transformation, quarks of the
same flavor and of opposite helicities mix to form a constituent quark. The
functional form of this unitary transformation can be strongly constrained on
the basis of symmetry arguments. This analysis is potentially rich in
phenomenological applications, and a few are presented here. The author offers
also some new theoretical results. No prior knowledge of light-cone formalism
on the part of the reader is assumed.


title: SU(3) Breaking Effects in Charmed Meson Decays

abstract:
  The decay rates of $D^+\to\pi^+\pi^0$ and $D^0\to K^+\pi^-$ recently measured
by CLEO give the ratios $R_1=2|V_{cs}/V_{cd}|^2\Gamma(D^+\to
\pi^+\pi^0)/\Gamma(D^+\to\bar{K}^0 \pi^+)=3.29\pm 1.16$ and
$R_2=|V_{cs}^*V_{ud}/(V_{cd}^*V_{us})|^2\Gamma(D^0\to
  K^+\pi^-)/\Gamma(D^0\to K^-\pi^+)=2.92\pm 1.34\,$. Both are about three times
of those expected from SU(3) symmetry. We show that, in the large-$N_c$
factorization approach, such large SU(3) violations can be accounted for by the
accumulations of several small SU(3)-breaking effects. An important requirement
is the relative magnitude of the form factors, $f_+^{D\pi}(0)>f_+^{DK}(0)$.


title: Top Quark As A Topological Color Soliton

abstract:
  In this paper I propose an scenario for the top quark as a topological color
soliton. I illustrate some features of the top quark as a soliton in a toy
model based on nonlinear realization of the $SU(3)_L \times SU(3)_R /
SU(3)_{L+R}$, with $SU(3)_{L+R}$ being the color gauge group.


title:
A Heavy Top Quark and the $Zb\bar{b}$ Vertex in Non-Commuting Extended
  Technicolor

abstract:
  We explore corrections to electroweak parameters in the context of Extended
Technicolor (ETC) models in which the ETC gauge-boson which generates the
top-quark mass carries weak $SU(2)$ charge. For $m_t \sim 150$ GeV there exist
potentially large corrections to the $Z$ decay width to $b$-quarks.
Interestingly, in contrast to the situation in ETC models where the gauge-boson
which generates the top-quark mass is a weak $SU(2)$ singlet, the corrections
may {\it increase} the $Z \to b \bar{b}$ branching ratio.


title: Deriving The Standard Model From Superstring Theory

abstract:
  I outline a program to derive the Standard Model directly from superstring
theory. I present a class of three generation superstring standard--like models
in the free fermionic formulation. I discuss some phenomenological properties
of these models. In particular these models suggest an explanation for the top
quark mass hierarchy. A numerical estimate yielded $m_t\sim175-180~GeV$. The
general texture of fermion mass matrices was obtained from analysis of
nonrenormalizable terms up to order $N=8$.I argue that the realistic features
of these models are due to the underlying $Z_2\times Z_2$ orbifold, with
standard embedding, at the free fermionic point in toroidal compactification
space.


title: Simple But Efficient Tests of QCD from Tau Decays$^{*)}$

abstract:
  We review the determinations of the QCD coupling $\alpha_s$ from the
inclusive and exclusive modes of $\tau$-decays. The most recent $\tau$-data
provide the average value $ \alpha_ s \left(M^2_\tau \right)\simeq 0.347\pm
0.030 $ corresponding to $ \alpha_ s \left(M^2_Z \right) \simeq 0.121\pm 0.003
\pm 0.001.$ The values of the QCD vacuum condensates extracted from the
inclusive weighted-moment distributions are consistent with the ones from QCD
spectral sum rules. Accurate estimates and further precision tests should be
reached in the next $\tau$C/B-factory machines. The $M_\tau$-stability test
from the $ e^+e^- \longrightarrow I=1 $ hadron data is also discussed.


title:
Trileptons from Chargino-Neutralino Production at the CERN Large Hadron
  Collider

abstract:
  We study direct production of charginos and neutralinos at the CERN Large
Hadron Collider. We simulate all channels of chargino and neutralino production
using ISAJET 7.07. The best mode for observing such processes appears to be
$pp\to\tw_1\tz_2\to 3\ell +\eslt$. We evaluate signal expectations and
background levels, and suggest cuts to optimize the signal. The trilepton mode
should be viable provided $m_{\tg}\alt 500-600$~GeV; above this mass, the decay
modes $\tz_2\to\tz_1 Z$ and $\tz_2\to H_{\ell}\tz_1$ become dominant, spoiling
the signal. In the first case, the leptonic branching fraction for $Z$ decay is
small and additional background from $WZ$ is present, while in the second case,
the trilepton signal is essentially absent. For smaller values of $m_{\tg}$,
the trilepton signal should be visible above background, especially if
$|\mu|\simeq m_{\tg}$ and $m_{\tell}\ll m_{\tq}$, in which case the leptonic
decays of $\tz_2$ are enhanced. Distributions in dilepton mass
$m(\ell\bar{\ell})$ can yield direct information on neutralino masses due to
the distribution cutoff at $m_{\tz_2}-m_{\tz_1}$. Other distributions that may
lead to an additional constraint amongst the chargino and neutralino masses are
also examined.


title: Large relativistic corrections to the positronium decay rate

abstract:
  Relativistic corrections to the positronium decay rate are calculated. They
are close to $40(\alpha /\pi)^2$ and $46(\alpha /\pi)^2$ for singlet and
triplet states respectively.


title: Instanton Contribution to $B \rightarrow X_u e \bar \nu $ Decay

abstract:
  We study instanton effects on inclusive semileptonic $b \rightarrow u$ decay
using the heavy quark effective field theory and the operator product
expansion. The effect contributes not only to the hadronic matrix element but
also to the coefficient functions in the operator product expansion. We find
that the coefficient function is singular near the boundaries of the phase
space. In order to use perturbative QCD reliably, it is necessary to introduce
smearing near the boundary. However the instanton contribution to $b
\rightarrow c$ decay seems negligibly small.


title:
Quantum Decoherence, Entropy and Thermalization in Strong Interactions
  at High Energy

abstract:
  Entropy is generated in high-multiplying events by a dynamical separation of
strongly interacting systems into partons and unobservable environment modes
(almost constant field configurations) due to confinement.


title: A Note on QED with Magnetic Field and Chemical Potentia

abstract:
  Using a generalized proper-time method, we obtain expressions for the fermion
density and the QED effective Lagrangian for an external magnetic field at
finite chemical potential. The effective Lagrangian and the density are here
written in terms of elementary functions, summed over a finite number of filled
Landau levels.


title:
Yukawa Coupling Thresholds: Application to the MSSM and the Minimal
  Supersymmetric SU(5) GUT

abstract:
  We consider a particular class of threshold corrections to Yukawa couplings
and mass relations in the MSSM and supersymmetric grand unified models. We give
a complete treatment of Yukawa coupling thresholds at the unification scale
$\Mx$ and the effective supersymmetry scale $\Ms$ and apply them to corrections
to the tree-level prediction $y_b(\Mx) = y_{\tau}(\Mx)$ in minimal
supersymmetric SU(5). We apply both gauge and Yukawa coupling thresholds to
gauge unification and the above Yukawa unification condition to find
predictions for the top quark mass, $M_t$, the superheavy vector boson mass
$\Mv$ and the colored Higgs triplet mass $\Mhs$. We discuss the dependencies of
$\Mx$ and $\Mhs$ on $\alpha_s(M_Z)$, $M_t$ and the sparticle spectrum as well
as those of $M_t$ on $\tan\beta$, $\alpha_s(M_Z)$ and the bottom quark mass,
$M_b$. The effect of the Yukawa coupling thresholds on $M_t$ are given for
representative sparticle spectra. We describe the quantitative differences
between these effects for low and high $\tan\beta$. We also give new bounds on
superheavy masses, incorporating proton decay as well as unification
constraints, the former leading to a lower bound on $\alpha_s$.


title:
Large scale structure from biased non-equilibrium phase transitions -
  percolation theory picture

abstract:
  We give an analytical description of the spatial distribution of domain walls
produced during a biased nonequilibrium phase transition in the vacuum state of
a light scalar field. We discuss in detail the spectrum of the associated
cosmological energy density perturbations. It is shown that the contribution
coming from domain walls can enhance the standard cold dark matter spectrum in
such a way as to account for the whole range of IRAS data and for the COBE
measurement of the microwave background anisotropy. We also demonstrate that in
case of a biased phase transition which allows a percolative description, the
number of large size domain walls is strongly suppressed. This offers a way of
avoiding excessive microwave background distorsions due to the gravitational
field of domain walls present after decoupling.


title:
Annihilation Cross Sections for Relic Densities in the Low Velocity
  Limit

abstract:
  A simple method to calculate the total annihilation cross section of massive
cold relics is presented. Exact expressions for $\arel$, $\brel$, and $\crel$
of $\sigma \vrel=\arel+\brel \vrel^2+\crel \vrel^4$ are obtained from simple
derivatives of the squared annihilation amplitude. Three examples are given. In
one example, the computed annihilation cross section of massive Dirac neutrinos
confirms recent correct calculations.


title: Production and decay of the Standard Model Higgs Bososn at LEP200

abstract:
  We collect and update theoretical predictions for the production rate and
decay branching fractions of the Standard Model Higgs boson that will be
relevant for the Higgs search at LEP200. We make full use of the present
knowledge of radiative corrections. We estimate the systematics arising from
theoretical and experimental uncertainties.


title: H dibaryon in the QCD sum rule

abstract:
  The QCD sum rule is applied to the H dibaryon and is compared to the flavor
non-singlet di-nucleon. We find that the H dibaryon is almost degenerate to the
di-nucleon in the $SU(3)_{flavor}$ limit and therefore is not deeply bound as
far as th\ e threshold parameter is adjusted not to have a di-nucleon bound
state. After introducing the $SU(3)_{f}$ breaking effects, the H dibaryon is
found to be bound by $40 MeV$ below the $\Lambda \Lambda$ threshold.


title:
Topologically non--trivial chiral transformations and their
  representations in a finite model space

abstract:
  The role of chiral transformations in effective theories modeling Quantum
Chromo Dynamics is reviewed. In the context of the Nambu--Jona--Lasinio model
the hidden gauge and massive Yang--Mills approaches to vector mesons are
demonstrated to be linked by a special chiral transformation which removes the
chiral field from the scalar--pseudoscalar sector. The role of this
transformation in the presence of a topologically non--trivial chiral field is
illuminated. The fermion determinant for such a field configuration is
evaluated by summing the discretized eigenvalues of the Dirac Hamiltonian. This
discretization is accomplished by demanding certain boundary conditions on the
quark fields leaving a finite model space. The properties of two sets of
boundary conditions are compared. When the topologically non-trivial chiral
transformation is applied to the meson fields the associated transformation of
the boundary conditions is shown to be indispensable. A constructive procedure
for transforming the boundary conditions is developed.


title: A New Method for Computing Helicity Amplitudes

abstract:
  An helicity formalism for perturbative calculations is presented. It is based
on the formal insertion in spinor lines of a complete set of states built up
with unphysical spinors. It is particularly convenient when massive spinors are
present. Its application to $e^+\,e^-\,\rightarrow b\,\bar b\,W^+W^-$ is
briefly discussed.


title:
Roles of Diquarks in the Nucleon for the Deep Inelastic Scattering and
  the Non-leptonic Weak Transitions

abstract:
  We study roles of quark-quark correlations in the baryons for the deep
inelastic structure function and the ${\Delta}I=1/2$ rule of the non-leptonic
weak hyperon decay. The quark-quark correlation is incorporated
phenomenologically as diquarks within the Nambu and Jona-Lasinio model. The
strong diquark correlations in the spin-0 channel enhance the ${\Delta}I=1/2$
weak matrix elements, and account for the ${\Delta}I=1/2$ rule. The ratio of
the nucleon structure functions $F_2^{n}(x)/F_2^{p}(x)$ also comes to agree
with experiment due to the diquark correlations.


title: Single $W_R$ Production in $e^-e^-$ Collisions at the NLC

abstract:
  Single $W_R$ production in $e^-e^-$ collisions at the NLC can be used to
probe the Majorana nature of the heavy neutrinos present in the Left-Right
Symmetric Model below the kinematic threshold for their direct production. For
colliders in the $\sqrt {s}=1-1.5$ TeV range, typical cross sections of order
$1-10 fb$ are obtained, depending on the specific choice of model parameters.
Backgrounds arising from Standard Model processes are shown to be small. This
analysis greatly extends the kinematic range of previous studies wherein the
production of an on-shell, like-sign pair of $W_R$'s at the NLC was considered.


title: Top-Down Approach to Unified Supergravity Models

abstract:
  We introduce a new approach for studying unified supergravity models. In this
approach all the parameters of the grand unified theory (GUT) are fixed by
imposing the corresponding number of low energy observables. This determines
the remaining particle spectrum whose dependence on the low energy observables
can now be investigated. We also include some SUSY threshold corrections that
have previously been neglected. In particular the SUSY threshold corrections to
the fermion masses can have a significant impact on the Yukawa coupling
unification.


title: A Simple Way of Calculating Cosmological Relic Density

abstract:
  A simple procedure is presented which leads to a dramatic simplification in
the calculation of the relic density of stable particles in the Universe.


title: Inclusive particle photoproduction to next-to-leading order

abstract:
  We study the inclusive photoproduction of neutral and charged pions and
$\eta$ at HERA, via the resolved photon mechanism, in QCD to next-to-leading
order. We present various distributions of phenomenological interest and study
the theoretical uncertainties due to the mass scales, and to photon and proton
sets of structure functions. A new set of fragmentation functions for charged
pions is also presented.


title: Impact Picture Model for Pbar-P Elastic Scattering

abstract:
  The predictions of an impact-picture model for proton-antiproton elastic
scattering are compared with the new UA4 experimental data in the Coulomb
interference region at the center-of-mass energy of $541 GeV$. The predicted
differential cross section, the parameter $\rho$ and the forward slope are in
very good agreement with the data.


title: A Light Scalar Top Quark in MSGUT

abstract:
  We reexamine a possibility for the existence of a light supersymmetric
partner of the top quark (stop) with mass 15$\sim$16GeV in the framework of the
minimal supergravity GUT model (MSGUT). Such a stop could explain the slight
excess of the high $p_{T}$ cross section of the $D^{*\pm}$-meson production in
the two-photon process at TRISTAN. We find two types of solution for the RGEs
in the MSGUT allowing the existence of the light stop. The type I [type II]
solution is characterized by the heavy [light] top quark, $m_t\simeq$ 150GeV
[100GeV], and the light [heavy] squarks . It is found that the type II solution
is more favorable because these parameter sets seem to satisfy all constraints
settled by the recent collider experiments as well as by the cosmological
considerations. The existence of such a stop could change the dominant decay
mode of sparticles, the top quark and the Higgs bosons. Consequently,the
present experimental bounds on the supersymmetric parameters as well as on
masses of the top and the Higgs could be weakened substantially. However, the
allowed parameter region is rather restricted and in turn masses and mixing
parameters of the other SUSY partners as well as masses of the Higgs and the
top are severely constrained.


title: Finite temperature effective actions for double wells

abstract:
  The problem of calculating the effective potential for a real scalar field
with a double--well potential is a possible preliminary to understanding
symmetry breaking phase transitions in the early universe. It is argued here
that it is necessary to include multiple saddle points in the path integral
formalism and that quadratic source terms are important. The resulting
effective action has a well--defined propagator expansion with a positive mass
and gives a new way of understanding high temperature expansions, but the
results are equally valid at low or zero temperatures.


title:
Muon Number Violating Processes in Single Particle Extensions of the
  Standard Model

abstract:
  We study the one-loop induced muon number processes when the standard model
is minimally extended to include a $\rm SU(2)$ singlet of a charged scalar
$h^+$ and a neutral fermion $N$. We find that $\mu \rightarrow e \gamma$ is
more sensitive for the former model whereas $\mu-e$ conversion in nuclei for
the latter. Effects of a scalar leptoquark $y^{1/3}$ and a heavy vector fermion
$E^-$, which induce tree level rare muon decays, are also discussed.


title: An improved effective potential for electroweak phase transitions

abstract:
  It is shown that improved potentials and corrected mass terms can be
introduced by using a quadratic source term in the path integral construction
for the effective action. The advantage of doing things this way is that we
avoid ever having to deal with complex propagators in the loop expansion. The
resulting effective action for electroweak phase transitions is similar to the
usual results.


title: Closing the Light Gluino Window in Supersymmetric Grand Unified Models

abstract:
  We study the light gluino scenario giving special attention to constraints
from the masses of the light CP-even neutral Higgs $m_h$, the lightest chargino
$m_{\chi^{\pm}_1}$, and the second lightest neutralino $m_{\chi^0_2}$, and from
the $b\rightarrow s\gamma$ decay. We find that minimal $N=1$ supergravity, with
a radiatively broken electroweak symmetry group and universality of scalar and
gaugino masses at the unification scale, is incompatible with the existence of
a light gluino.


title:
Transverse Polarization of Top Quarks Produced at a Photon-Photon
  Collider

abstract:
  At future $\gamma \gamma$ colliders copious production of $t \bar{t}$ pairs
is possible. This would allow a detailed investigation of the interactions
involving the top quark. We propose some orrelations which are sensitive to $t
\bar{t}$ final state interactions and we compute the QCD and standard model
Higgs boson contributions to these correlations. QCD induced transverse
polarization of top quarks is found to be sizeable and measurable at a
high-energy $e^+e^-$ collider with an integrated luminosity of 10 $({\rm
fb})^{-1}$ which is converted into a photon collider by backscattering of laser
photons.


title: The Reaction $\pi N \to \pi \pi N$ at Threshold

abstract:
  We consider the chiral expansion for the reaction $\pi N \to \pi \pi N$ in
heavy baryon chiral perturbation theory. To order $M_\pi$ we derive novel
low--energy theorems that compare favorably with recent determinations of the
total cross sections for $\pi^+ p \to \pi^+ \pi^+ n$ and $\pi^- p \to \pi^0
\pi^0 n$.


title: Multiplicities for LHC Nuclear Collisions Using HERA Structure Functions

abstract:
  We compute in QCD perturbation theory the transverse energy carried by
gluons, quarks and antiquarks with $p_T\ge p_0\approx 2$ GeV in Pb+Pb
collisions at $\sqrt{s}=5500$ $A$GeV by using structure functions compatible
with the small-$x$ increase observed at HERA. This gives a perturbative
estimate for the energy and entropy density of the bulk system at times
$\tau\sim 0.1$ fm. The predicted initial gluon entropy density gives a lower
limit of about 2200...3400 for the final charged multiplicity. Sources of
further entropy increase are discussed.


title:
Predictions for Proton Lifetime in Minimal Non-Supersymmetric SO(10)
  Models: An Update

abstract:
  We present our best estimates of the uncertainties due to heavy particle
threshold corrections on the unification scale $M_U$, intermediate scale $M_I$
and coupling constant Alpha_U in the minimal non-supersymmetric SO(10) models.
Using these , we update the predictions for proton life-time in these models.


title: The Equivalence Theorem for Chiral Lagrangians

abstract:
  In this work we derive the version of the Equivalence Theorem that applies
when the symmetry breaking sector of the Standard Model is described by a
general chiral lagrangian. The demonstration is valid for renormalized fields
for any value of the gauge parameter (in $R_{\xi}$ gauges) and any
parametrization of the coset space. It is based in the absence of gauge
anomalies which makes it possible to build an (anti)-BRS invariant chiral
lagrangian in terms of the renormalized fields and therefore to use the
corresponding Ward identities to obtain the theorem.


title: Remark on Charm Quark Fragmentation to $D^{**}$ Mesons

abstract:
  The observed $D^{**}$ mesons have $c\bar q$ flavor quantum numbers and
spin-parity of the light degrees of freedom $s_\ell^{\pi_{\ell}} = 3/2^+$. In
the $m_c \rightarrow \infty$ limit the spin of the charm quark is conserved and
the $c \rightarrow D^{**}$ fragmentation process is characterized by the
probability for the charm quark to fragment to a $D^{**}$ meson with a given
helicity for the light degrees of freedom. We consider the calculated $b
\rightarrow B_c^{**}$ fragmentation functions in the limit $m_c/m_b \rightarrow
0$ as a qualitative model for the $c \rightarrow D^{**}$ fragmentation
functions. We find that in this model charm quark fragmentation to
$s_\ell^{\pi_{\ell}} = 3/2^+$ light degrees of freedom with helicities $\pm
1/2$ is favored over fragmentation to $s_\ell^{\pi_{\ell}} = 3/2^+$ light
degrees of freedom with helicities $\pm 3/2$.


title: A Model of CP Violation

abstract:
  It is shown that a two-Higgs doublet model with Vacuum CP Violation and
Approximate Global $U(1)$ Family Symmetries (AGUFS) may provide one of the
simplest and attractive models in understanding origin and mechanisms of CP
violation at the weak scale. The whole new interactions of the model are
explicitly presented here. It is seen that CP violation can occur, after
spontaneous symmetry breaking, everywhere it can from a single CP-phase in the
vacuum. It is also shown that "the mechanism of spontaneous symmetry breaking
provides not only a mechanism for giving mass to the bosons and the fermions,
but also a mechanism for generating CP-phase of the bosons and the fermions".
Four types of CP-violating mechanism are classified. A new type of CP-violating
mechanism is emphasized and can provide a consistent application to both the
established and the reported CP-violating phenomena. The smallness of the CKM
mixing angles and the induced KM-type CP-violating effects as well as the
suppression of flavor-changing neutral scalar interactions can be attributed to
the AGUFS and Partial Conservation of Neutral Flavor (PCNF). This suggests that
if one Higgs doublet is necessary for generation of mass, two Higgs doublets
are then needed for origin and phenomenology of CP violation. Various
interesting phenomenological features arising from this model are analyzed.
Their experimental implications and importance are discussed and emphasized.
Directly searching for the exotic Higgs bosons introduced in this model is
worthwhile at both $e^{+}e^{-}$ and hadron colliders.


title: The Rho-Meson as a Collective Excitation

abstract:
  A model of the rho-meson as a collective excitation of $q\bar{q}$ pairs in a
system that obeys the modified Nambu--Jona-Lasinio Lagrangian is proposed. The
rho emerges as a dormant Goldstone boson. The origin of the rho-meson mass is
understood as a result of spontaneous chiral symmetry breaking. The low-energy
dynamics of rho, pi, omega and gamma is consistently described in this new
framework. The model accounts for the origin of the celebrated
Kawarabayashi--Suzuki--Riazuddin--Fayyazuddin relation.


title: Proton Life-Time Problem In Finite Grand Unified Theories

abstract:
  We study proton decay in finite supersymmetric SU(5) grand unified theories.
We find that the dimension-five operators due to color triplet higgsino induce
too rapid a proton decay. This behaviour can be traced to the large Yukawa
couplings to the first generation that are necessary for finiteness.


title: Standard Model Higgs Physics at a 4 TeV Upgraded Tevatron

abstract:
  We compute an array of Standard Model Higgs boson ($\hsm$) signals and
backgrounds for a possible upgrade of the Tevatron to $E_{\rm cm}=4\tev$.
Taking $\mt\geq 140\gev$, and assuming a total accumulated luminosity of
$L=30\fbi$, we find that a Standard Model Higgs boson with $\mhsm\lsim 110\gev$
could almost certainly be detected using the $\wpm\hsm\rta l\nu b\anti b$ mode.
A Higgs boson with mass between $\sim 120\gev$ and $\sim 140\gev$ or above
$\sim 230-250\gev$ almost certainly would not be seen. A Higgs boson with
$\mhsm\sim 150\gev$ or $200\lsim\mhsm\lsim 230-250\gev$ has a decent chance of
being detected in the $ZZ\rta 4l$ mode. There would also be some possibility of
discovering the $\hsm$ in the $WW\rta l\nu jj$ mode for $150\lsim\mhsm\lsim
200\gev$. Finally, hints of an event excess in the $WW\rta ll \nu\nu$ mode due
to the $\hsm$ might emerge for $140\lsim\mhsm\lsim 180\gev$. Given the
difficult nature of the Higgs boson signals for $\mhsm$ values beyond the reach
of LEP-200, and the discontinuous $\mhsm$ range that could potentially be
probed, justification of an upgrade of the Tevatron to $4\tev$ on the basis of
its potential for Standard Model Higgs boson discovery would seem
inappropriate.


title:
Polarization observables of the $\vec{d} \vec{p} \rightarrow \vec{p}d$
  reaction and one-neutron-exchange approximation

abstract:
  The polarization observables in the elastic scattering of polarized deuterons
on a polarized hydrogen target, with measurement of the recoil proton
polarization, are considered. The observables are calculated in the one-neutron
exchange approximation, for the special case of backward scattering
($\theta_{c.m.} = 180^{\circ}$). Several new relations between polarization
observables of the reaction are derived within the framework of this
approximation.


title:
`Natural Masslessness Conservation' for neutrinos in two Higgs-doublet
  models

abstract:
  We present a model which supplements the Standard Electroweak Model with
three right-handed neutrinos and one extra scalar doublet which does not
develop a vacuum expectation value. With the aid of a discrete symmetry the
neutrinos are kept strictly massless. This model has several interesting
features. It has unsuppressed lepton flavour violating processes, in particular
$\mu \rightarrow e \gamma$, hinting at the possibility that these may soon be
within experimental reach. The $Z$ and $W$ interactions become non-diagonal at
one loop level. In particular, a non-trivial leptonic mixing matrix is seen to
arise from the clash between the charged gauge boson and the charged scalar
interactions.


title:
Associated Production of Higgs and Weak Bosons, with H -> b\bar b, at
  Hadron Colliders

abstract:
  We consider the search for the Higgs boson at a high-luminosity Fermilab
Tevatron, an upgraded Tevatron of energy 3.5 TeV, and the CERN Large Hadron
Collider, via $WH/ZH$ production followed by H -> bb~ and leptonic decay of the
weak vector bosons. We show that each of these colliders can potentially
observe the standard Higgs boson in the intermediate-mass range, 80 GeV <m_H <
120 GeV. This mode complements the search for and the study of the
intermediate-mass Higgs boson via H -> \gamma\gamma at the LHC. In addition, it
can potentially be used to observe the lightest Higgs scalar of the minimal
supersymmetric model in a region of parameter space not accessible to CERN LEP
II or the LHC (using h -> \gamma\gamma,ZZ^*).


title: Ultraviolet-Renormalon Reexamined

abstract:
  We consider large-order perturbative expansions in QED and QCD. The
coefficients of the expansions are known to be dominated by the so called
ultraviolet (UV) renormalons which arise from inserting a chain of
vacuum-polarization graphs into photonic (gluonic) lines. In large orders the
contribution is associated with virtual momenta $k^2$ of order $Q^2e^n$ where
$Q$ is external momentum, $e$ is the base of natural logs and $n$ is the order
of perturbation theory considered. To evaluate the UV renormalon we develop
formalism of operator product expansion (OPE) which utilizes the observation
that $k^2\gg Q^2$. When applied to the simplest graphs the formalism reproduces
the known results in a compact form. In more generality, the formalism reveals
the fact that the class of the renormalon-type graphs is not well defined. In
particular, graphs with extra vacuum-polarization chains are not suppressed.
The reason is that while inclusion of extra chains lowers the power of $\ln
k^2$ their contribution is enhanced by combinatorial factors.


title:
Residual long-range pseudoscalar forces between unpolarised macroscopic
  bodies

abstract:
  In this paper we survey the effects of residual long-range forces associated
to $\gamma_5$-spin dependent-couplings of fermions to massless bosons exerted
by unpolarised bulk matter over macroscopic distances. We establish that such
forces with behaviour proportional to $R^{-6}$ do indeed exist. They arise as a
quantum mechanical effect due to simultaneous exchange of two quanta. We
explore their presence in existing astronomical as well as laboratory data on
non-newtonian components of the force between macroscopic bodies. Since no
limits on their real existence could be found, we conclude that residual
long-range pseudoscalar attractive and composition dependent forces between
neutral unpolarised bulk matter extending over macroscopic distances are very
efficiently shielded over a huge range of distances: from astronomical scales
down to the micron scale.


title:
Heavy quark potential and the phase transitions in the continuum theory
  at finite temperature

abstract:
  Heavy quark potential in the continuum theory at finite temperature is
calculated in different phases by using the Polyakov loop as the order
parameter. We find the linearly rising potential in the confinement phase, the
Debye screened potential in the deconfinement phase and the perturbative
$r^{-2}$ dependence at very high temperatures. Within the approximation used in
this paper we report an evidence of the first order phase transition
accompanied by the $SU(2)$ symmetry restoration at very high temperatures in
the static three dimensional theory.


title:
Curvature energy effects on strange quark matter nucleation at finite
  density

abstract:
  We consider the effects of the curvature energy term on thermal strange quark
matter nucleation in dense neutron matter. Lower bounds on the temperature at
which this process can take place are given and compared to those without the
curvature term.


title: The Indirect Detection of Halo Dark Matter

abstract:
  High energy particles are produced by the annihilation of dark matter
particles in our galaxy. These are presently searched for using balloon-borne
antiproton and positron detectors and large area, deep underground neutrino
telescopes. Dark matter particles, trapped inside the sun, are an abundant
source of such neutrinos.
  From both the cosmological and particle physics points of view the lightest,
stable supersymmetric particle or neutralino is arguably the leading dark
matter candidate. Its mass is bracketed by a minimum value of order a few tens
of GeV, determined from unsuccessful accelerator searches, and a maximum value
of order 1~TeV imposed by particle physics as well as cosmological constraints.
Back-of-the-envelope calculations are sufficient to demonstrate how present
neutrino telescopes are competitive with existing and future particle colliders
such as the LHC in the search for supersymmetry. We emphasize that a $1\,\rm
km^2$ area is the natural scale for a future instrument capable of probing the
full GeV--TeV neutralino mass range by searching for high energy neutrinos
produced by their annihilation in the sun.


title:
Predictions for Constrained Minimal Supersymmetry with Bottom-Tau Mass
  Unification

abstract:
  We examine the Constrained Minimal Supersymmetric Standard Model (CMSSM) with
an additional requirement of strict b - tau unification in the region of small
tan(beta). We find that the parameter space becomes completely limited below
about 1 TeV by physical constraints alone, without a fine-tuning constraint. We
study the resulting phenomenological consequences, and point out several ways
of falsifying the adopted b - tau unification assumption. We also comment on
the effect of a constraint from the non-observation of proton decay.


title:
Fragmentation Function Method for Charge Asymmetry Measurements in
  $\e^+e^-$ Collisions

abstract:
  We propose a method for measuring the hadron charge asymmetry in $\ee$
collisions which is based upon the fragmentation function formalism, and is
largely independent of modelling of fragmentation effects. Furthermore, in this
method, QCD radiative corrections can be accounted for in a systematic way.


title: Vacuum Structure in QCD with Quark and Gluon Condensates

abstract:
  We consider here the vacuum structure in QCD with both quark and gluon
condensates and a variational ansatz for the ground state. The method is
nonperturbative using only equal time algebra for the field operators. We then
find that a constrained energy minimisation of the Hamiltonian leads to a QCD
vacuum with both quark and gluon condensates for $\alpha_s > \alpha_c=0.62$.
Pion decay constant and the charge radius of the pion seem to fix the QCD
coupling constant $\alpha_s$ as 1.28. The approach opens up possibilities of
relating the mysterious vacuum structure with common place hadronic properties.


title: Summary Talk at the 3rd KEK Topical Conference on CP Violation

abstract:
  A summary of the contributions to this topical conference is presented. The
topics discussed ranged from detailing what we know about CP violation, to what
we hope to learn in the future, to still unsolved mysteries in the subject.


title:
Can the Supersymmetric $\mu$ parameter be generated dynamically without
  a light Singlet?

abstract:
  It is generally assumed that the dynamical generation of the Higgs mass
parameter of the superpotential, $\mu$, implies the existence of a light
singlet at or below the supersymmetry breaking scale, $\msusy$. We present a
counter-example in which the singlet field can receive an arbitrarily heavy
mass (\eg, of the order of the Planck scale, $M_{\rm P}\approx 10^{19}~\gev$).
In this example, a non-zero value of $\mu$ is generated through soft
supersymmetry breaking parameters and is thus naturally of the order of
$\msusy$.


title:
The forward-backward asymmetry with $Z'$ effects in the process $e^{+}$
  $e^{-}$ $\rightarrow$ $\mu^{+}$ $\mu^{-}$

abstract:
  Having taken the QED radiative correction and one-loop weak corrections into
account, we have computed the unpolarized forward-backward asymmetry in the
process $e^+e^- -> \mu^+\mu^-$ at a very reasonable accuracy. Special attention
to the effects around the LEP 200 energy, induced by the possible $Z'$ boson of
the left-right symmetric model $SU(2)_{L} \times SU(2)_{R} \times U(1)_{B-L}$,
is paid. The numerical results of the directly measurable asymmetry
$A_{FB}^{\mu}$ versus the CMS energies are presented in figures. One may be
convinced by the results that precise measurements on the asymmetry in future
colliders will possibly present some indirectly evidence of the $Z'$ boson.


title:
$W^+-H^+$ Interference and Partial Width Asymmetry in Top and Antitop
  Decays

abstract:
  We re-examine the question of a possible difference in the partial decay
widths of $t$ and $\overline t$, induced by an intermediate scalar boson $H^+$
with $CP$-violating couplings. The interference of $W^+$ and $H^+$ exchanges is
analysed by constructing the $2\times 2$ propagator matrix of the $W^+-H^+$
system, and determining its absorptive part in terms of fermion loops. Results
are obtained for the partial rate difference in the channels $t\to bl^+\nu_l $
and $t\to bc\overline s$, which fulfil explicitly the constraints of $CPT$
invariance. These results are contrasted with those in previous work.


title:
On collinearization of quarks in the quark-gluon decays of heavy
  orthoquarkonia

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 probability distributions of quarks and
gluons are obtained. The collinear enhancement of the bottomonium decay is
shown to take place at the u\={u}--, d\={d} and s\={s}-- pair production and to
be absent at the c\={c}-- production. Some other peculiarities of the
considered decays are discussed. (Published in Mod.Phys.Lett A 9 (1994) 115).


title: CKM Matrix from Leptoquark-Quark Mixing in a String Model

abstract:
  We investigate a scenario in which the CKM matrix arises from
leptoquark--down quark mixing in a particular standard--like superstring model.
We find that for some choices of F and D flat directions realistic quark mixing
can be obtained without any phenomenological problems. This scenario predicts a
symmetric (in absolute value) CKM matrix.


title: What is being calculated with Thermal Field Theory?

abstract:
  Thermal field theory is reviewed briefly. It is noted that, until recently,
it was not known what type of real-time Green function is being calculated in
the Euclidean approach. The formal answer to this question is then given and
the unexpectedly complicated answer is discussed. The physical implications of
the results are then considered. (Talk given at the Lake Louise Winter
Institute on Particle Physics and Cosmology, 20th - 26th February, 1994, Lake
Louise, Canada)


title: Implications of a Heavy Top in Supersymmetric Theories

abstract:
  In the context of the radiative electroweak symmetry breaking scenario, we
investigate the implications of a heavy top quark mass, close to its infrared
fixed point, on the low energy parameters of the minimal supersymmetric
standard model. We use analytic expressions to calculate the Higgs masses as
well as the supersymmetric masses of the third generation. We further assume
bottom-tau unification at the GUT scale and examine the constraints put by this
condition on the parameter space ($\tan\beta$,$\alpha_3$), using the
renormalization group procedure at the two-loop level. We find only a small
fraction of the parameter space where the above conditions can be satisfied,
namely $1\le \tan\beta \le 2$, while $0.111\le\alpha_3(M_Z) \le 0.118$. We
further analyse the case where all three Yukawa couplings reach the
perturbative limit just after the unification scale. In this latter case, the
situation turns out to be very strict demanding $\tan\beta\sim 63$.


title: Breaking Electroweak Symmetry Strongly

abstract:
  The problem of electroweak symmetry breaking is reviewed with discussion of
future relevant experimentation at LHC and $e^+e^-$ linear colliders. The
possibility of strong electroweak symmetry breaking is examined in more detail,
using the BESS (Breaking Electroweak Symmetry Strongly) model as a basis for
the discussion. The formal constructions are briefly presented and the possible
expectations at future colliders are summarized.


title: Possible Extension of the Chiral Perturbation Theory Program

abstract:
  After a brief discussion of how chiral dynamics has evolved from the
``universal V-A theory of weak interactions'', we present some evidence that
symmetry breaking for the vector meson multiplet is not simpler than but rather
analogous to that for the pseudoscalar multiplet. This provides a motivation
for speculating on how to extend in a systematic way the chiral perturbation
theory program to include vectors.


title: SUSY Magnetic Moments Sum Rules and Supersymmetry Breaking

abstract:
  It was recently shown that unbroken N=1 Susy relates, in a model independent
way, the magnetic transitions between states of different spin within a given
charged massive supermultiplet. We verify explicitly these sum rules for a
vector multiplet in the case of massless and massive fermions. The purpose of
this analysis is to provide the ground for the broken susy case. We study the
modifications of these results when an explicit soft Susy breaking realized
through a universal mass for all scalars is present. As a by-product we provide
a computation of the $g-2$ of the $W$ boson in the standard model which
corrects previous evaluations in the literature.


title: From Multiloop Spinor Helicity Technique to String Reorganization

abstract:
  The success of the spinor helicity technique for tree processes is reviewed.
To apply it to multiloop diagrams one is naturally led to the Schwinger
proper-time representation, whose properties are discussed. This representation
also serves as a useful link between field theories and string theories.


title: Vacuum stability in the singlet Majoron model

abstract:
  We study the vacuum stability of the singlet Majoron model using full
renormalization group improved scalar potential and Monte Carlo techniques. We
show that in the perturbative regime of the various free parameters, the vacuum
stability requirement together with LEP limits is passed by 18% of the
parameter space if the scale of new physics is 10 TeV and 6% if the scale is
$10^{14}$ GeV. Moreover, if the baryogenesis condition for scalar couplings is
required, no portion of the parameter space survives.


title: The Threshold Pion-Photoproduction of Nucleons In The Chiral Quark Model

abstract:
  In this paper, we show that the low energy theorem (LET) of the threshold
pion-photoproduction can be fully recovered in the quark model. An essential
result of this investigation is that the quark-pion operators are obtained from
the effective chiral Lagrangian, and the low energy theorem does not require
the constraints on the internal structures of the nucleon. The pseudoscalar
quark-pion coupling generates an additional term at order $\mu=m_{\pi}/M$ only
in the isospin amplitude $A^{(-)}$. The role of the transitions between the
nucleon and the resonance $P_{33}(1232)$ and P-wave baryons are also discussed,
we find that the leading contributions to the isospin amplitudes at $O(\mu^2)$
are from the transition between the P-wave baryons and the nucleon and the
charge radius of the nucleon. The leading contribution from the P-wave baryons
only affects the neutral pion production, and improve the agreement with data
significantly. The transition between the resonance $P_{33}(1232)$ and the
nucleon only gives an order $\mu^3$ corrections to $A^{(-)}$.


title:
Measurement of the Spin-Dependent Structure Function $g_1(x)$ of the
  Proton

abstract:
  We have measured the spin-dependent structure function $g_1^p$ of the proton
in deep inelastic scattering of polarized muons off polarized protons, in the
kinematic range $0.003<x<0.7$ and $1\,\mbox{GeV}^2<Q^2<60\,\mbox{GeV}^2$. Its
first moment, $\int_0^1 g_1^p(x) dx $, is found to be $0.136 \pm
0.011\,(\mbox{stat.})\pm 0.011\,(\mbox{syst.})$ at $Q^2=10\,\mbox{GeV}^2$. This
value is smaller than the prediction of the Ellis--Jaffe sum rule by two
standard deviations, and is consistent with previous measurements. A combined
analysis of all available proton, deuteron and neutron data confirms the
Bjorken sum rule to within $10\%$ of the theoretical value.


title: Origin and Mechanisms of CP Violation

abstract:
  It is shown that the mechanism of spontaneous symmetry breaking provides not
only a mechanism for giving mass to the bosons and the fermions, but also a
mechanism for generating CP-phase of the bosons and the fermions. A two-Higgs
doublet model with Vacuum CP Violation and Approximate Global $U(1)$ Family
Symmetries (AGUFS) is built and may provide one of the simplest and attractive
models in understanding origin and mechanisms of CP violation at the weak
scale. It is seen that CP violation occurs everywhere it can from a single CP
phase of the vacuum and is generally classified into four types of CP-violating
mechanism. A new type of CP-violating mechanism is emphasized and can provide a
consistent application to both the established and the reported CP-, T- and
P-violating phenomena.


title: Baryon Asymmetry from a Two Stage Electroweak Phase Transition ?

abstract:
  We investigate an extension of the standard model with a second Higgs
doublet, showing a two stage phase transition. Wash-out of a baryon asymmetry
after the phase transition can be easily avoided in this class of models. B+L
transitions are more strongly suppressed in the intermediate phase than in the
high temperature symmetric phase,however. Therefore, it becomes more difficult
if not impossible to generate a sufficient baryon asymmetry during the phase
transition.


title: Scattering from Electroweak Strings

abstract:
  The scattering of a charged fermion from an electroweak string is studied.
Owing to an amplification of the wave function at the core radius, the cross
sections for helicity flip processes can be largely enhanced. For $0 <\sin^2
\theta_w < 1/2 $ (where $\theta_w$ is the Weinberg angle), $\omega \sim k \sim
m_e$ and $kR \ll 1$, we show that the helicity flip differential cross section
for electrons is of the order $m_e^{-1}$ and is independent of angle. We
compare our results with those obtained in calculations of rates for baryon
number violating processes in the core of a cosmic string. In that case, while
the enhancement is a general phenomenon, its actual magnitude is extremely
sensitive to the fractional flux carried by the string core. Apart from showing
the existence of a similar enhancement effect for non-topological strings, our
results indicate that in some models the magnitude of enhancement can be
rendered much less sensitive to the value of the parameters in the theories.
Scattering of particles off semi-local strings and axion strings are also
considered.


title: Skyrmion Quantization and the Decay of the Delta

abstract:
  We present the complete solution to the so-called ``Yukawa problem'' of the
Skyrme model. This refers to the perceived difficulty of reproducing---purely
from soliton physics---the usual pseudovector pion-nucleon coupling, echoed by
pion coupling to the higher spin/isospin baryons $(I=J=3/2 , 5/2 , \cdots ,
N_c/2 )$ in a manner fixed by large-$N_c$ group theory. The solution involves
surprisingly elegant interplay between the classical and quantum properties of
a new configuration, the ``new improved skyrmion''. This is the near-hedgehog
obtained by minimizing the usual skyrmion mass functional augmented by an
all-important isorotational kinetic term. The numerics are pleasing: a $\Delta$
decay width within a few MeV of its measured value, and furthermore, the
higher-spin baryons $(I=J \ge 5/2 )$ with widths so large ($\Gamma > 800 MeV$)
that these undesirable large-$N_c$ artifacts effectively drop out of the
spectrum, and pose no phenomenological problem. Beyond these specific results,
we ground the Skyrme model in the Feynman Path Integral, and set up a
transparent collective coordinate formalism that makes maximal use of the
$1/N_c$ expansion. This approach elucidates the connection between skyrmions on
the one hand, and Feynman diagrams in an effective field theory on the other.


title:
Exact Sum Rules at Finite Temperature and Chemical Potential and Their
  Application to QCD

abstract:
  Within the framework of the operator product expansion (OPE) and the
renormalization group equation (RGE), we show that the temperature and chemical
potential dependence of the zeroth moment of a spectral function (SF) is
completely determined by the one-loop structure of an asymptotically free
theory. This exact result constrains the shape of SF's, and implies a highly
non-trivial functional form for the SF near second order, or weak first order,
phase transitions. Phenomenological parameterizations of the SF, often used in
applications such as the analysis of lattice QCD data or QCD sum rule
calculations at finite temperature and baryon density, must satisfy these
constraints.


title:
Fundamental CP-violating quantities in a SU(2)$ \otimes $U(1) model with
  many Higgs doublets

abstract:
  We consider a SU(2)$ \otimes $U(1) gauge theory with many scalar doublets,
but without fermions. We devise a systematic method of constructing quantities
which are invariant under changes of basis of the scalar fields, but acquire a
minus sign under a general CP transformation. Those quantities provide a
basis-independent way of checking for the existence of CP violation.


title: Target Independence of the Emc-SMC Effect

abstract:
  An approach to deep inelastic scattering is described in which the matrix
elements arising from the operator product expansion are factorised into
composite operator propagators and proper vertex functions. In the case of
polarised $\m p$ scattering, the composite operator propagator is identified
with the square root of the QCD topological susceptibility
$\sqrt{\chi^{\prime}(0)}$, while the corresponding proper vertex is a
renormalisation group invariant. We estimate $\chi^{\prime}(0)$ using QCD
spectral sum rules and find that it is significantly suppressed relative to the
OZI expectation. Assuming OZI is a good approximation for the proper vertex,
our predictions, $\int_{0}^{1}dx g_1^p (x;Q^2=10\GV^2)= 0.143 \pm 0.005$ and
$G^{(0)}_A \equiv \Delta \Sigma = 0.353 \pm 0.052$, are in excellent agreement
with the new SMC data. This result, together with one confirming the validity
of the OZI rule in the $\hp$ radiative decay, supports our earlier conjecture
that the suppression in the flavour singlet component of the first moment of
$g_1^p$ observed by the EMC-SMC collaboration is a target-independent feature
of QCD related to the $U(1)$ anomaly and is not a property of the proton
structure. As a corollary, we extract the magnitude of higher twist effects
from the neutron and Bjorken sum rules.


title: Strings versus supersymmetric GUTs: can they be reconciled?

abstract:
  We describe a class of supersymmetric unified models with the following
properties:
  i) the full breaking of the gauge group is achieved by Higgs fields in the
fundamental representation;
  ii) the correct unification of the strong and electroweak coupling constants
is obtained without the need of any intermediate scale;
  iii) the problems of the doublet-triplet splitting and of the proton decay at
dimension-5 level may receive a natural solution.
  The models, other than being interesting unified field theories per se, may
constitute examples of string-derivable GUTs.


title: $\pi$-$A_1$ electromagnetic form factors and light-cone QCD sum rules

abstract:
  Electromagnetic form factors of the transition $\pi+\gamma_{virt.}\ra A_1$
are calculated by QCD sum rules technique with the description of the pion in
terms of the set of wave functions of increasing twist. Obtained results are
compared with standard QCD sum rule calculations.


title: Prospects of Measuring the Parity of Higgs Particles

abstract:
  We analyze the prospects of measuring the parity of Higgs particles in the
Standard Model and its supersymmetric extensions. Higgs decays are discussed in
this context as well as production processes including, in particular, the
fusion of Higgs particles in linearly polarized photon--photon collisions.


title: Measuring Strong and Weak Phases in Time-Independent B Decays

abstract:
  Flavor SU(3) symmetry implies certain relations among $B$-decay amplitudes to
$\pi\pi$, $\pi K$ and $K {\bar K}$ final states, when annihilation-like
diagrams are neglected. Using three triangle relations, we show how to measure
the weak CKM phases $\alpha$ and $\gamma$ using time-independent rate
measurements only. In addition, one obtains all the strong final-state phases
and the magnitudes of individual terms describing tree (spectator),
color-suppressed and penguin diagrams. Many independent measurements of these
quantities can be made with this method, which helps to eliminate possible
discrete ambiguities and to estimate the size of SU(3)-breaking effects.


title:
Weak Coupling Phase from Decays of Charged B Mesons to $\pi K$ and
  $\pi\pi$

abstract:
  The theory of $CP$ violation based on phases in weak couplings in the
Cabibbo-Kobayashi-Maskawa (CKM) matrix requires the phase $\gamma \equiv {\rm
Arg~} V^*_{ub}$ (in a standard convention) to be nonzero. A measurement of
$\gamma$ is proposed based on charged $B$ meson decay rates to $\pi^+ K^0$,
$\pi^0 K^+$, $\pi^+ \pi^0$, and the charge-conjugate states. The corresponding
branching ratios are expected to be of the order of $10^{-5}$. (submitted to
Physical Review Letters)


title: Decays of $B$ Mesons to Two Light Pseudoscalars

abstract:
  The decays $B \to PP$, where $P$ denotes a pseudoscalar meson, are analyzed,
with emphasis on charmless final states. Numerous triangle relations for
amplitudes hold within SU(3) symmetry, relating (for example) the decays $B^+
\to \pi^+ \pi^0,~ \pi^0 K^+$, and $\pi^+ K^0$. Such relations can improve the
possibilities for early detection of $CP$-violating asymmetries. Within the
context of a graphical analysis of decays, relations are analyzed among SU(3)
amplitudes which hold if some graphs are neglected. One application is that
measurements of the rates for the above three $B^+$ decays and their
charge-conjugates can be used to determine a weak CKM phase. With measurements
of the remaining rates for $B$ decays to $\pi \pi,~\pi K$, and $K \bar K$, one
can obtain two CKM phases and several differences of strong phase shifts.


title: The $O(g^4)$ Lipatov Kernels

abstract:
  Leading plus next-to leading log results for the Regge limit of massless
Yang-Mills theories are reproduced by reggeon diagrams in which the Regge slope
$\alpha' \to 0$ and reggeon amplitudes satisfy Ward identity constraints at
zero transverse momentum. Using reggeon unitarity together with multiple
discontinuity theory a complete set of such diagrams can be constructed. The
resulting two-two, one-three and two-four kernels which generalise the Lipatov
equation at $O(g^4)$ are determined uniquely.


title:
$\Lambda (1405)$ Contribution to Kaon-Nucleon Scattering Lengths In
  Chiral Perturbation Theory

abstract:
  We examine the role of the $\Lambda(1405)$ in kaon-nucleon scattering lengths
using chiral perturbation theory. The leading nonanalytic SU(3) corrections
reduce the coupling of the $\Lambda (1405)$ to $KN$ compared to $\Sigma\pi$.
S-wave $K^-p$ scattering is the only channel significantly affected by the $
\Lambda (1405)$ pole which substantially cancels against the leading term fixed
by the vector current. This cancellation and the close proximity of the
$\Lambda (1405)$ pole makes this SU(3) correction to $a(K^-p)$ large and at
lowest order leaves the sign of $a(K^-p)$ undetermined. We extract two linear
combinations of constants appearing at higher order in the chiral expansion
from measurements of $KN$ scattering lengths. These constants are important for
the offshell behaviour of $KN$ scattering amplitudes that play a central role
in kaon condensation. The recent claims about the calculability of these
constants are discussed.


title: Finite-Element Time Evolution Operator for the Anharmonic Oscillator

abstract:
  The finite-element approach to lattice field theory is both highly accurate
(relative errors $\sim1/N^2$, where $N$ is the number of lattice points) and
exactly unitary (in the sense that canonical commutation relations are exactly
preserved at the lattice sites). In this talk I construct matrix elements for
dynamical variables and for the time evolution operator for the anharmonic
oscillator, for which the continuum Hamiltonian is $H=p^2/2+\lambda q^4/4.$
Construction of such matrix elements does not require solving the implicit
equations of motion. Low order approximations turn out to be extremely
accurate. For example, the matrix element of the time evolution operator in the
harmonic oscillator ground state gives a result for the anharmonic oscillator
ground state energy accurate to better than 1\%, while a two-state
approximation reduces the error to less than 0.1\%.


title:
DISJET 1.2: A Monte Carlo Program for Jet Cross Section Calculations in
  Deep Inelastic Scattering

abstract:
  We present a new parton level Monte Carlo program for the calculation of jet
cross sections in Deep Inelastic Scattering based on Born and next-to-leading
order matrix elements. Using a class of invariant jet definition schemes, the
program allows for the calculation of differential distributions of jet cross
sections in the basic kinematical variables (like s, x, y, W^2, Q^2...) as well
as for total jet cross sections. Various kinematical cuts can be chosen from an
input file.


title:
Double radiative decay $Z \rightarrow f\bar{f}\gamma\gamma$ in the
  Standard Model

abstract:
  Z-boson decay $Z \rightarrow f\tilde{f}\gamma\gamma$ in the Standard Model is
analysed. The distribution function on the invariant masses of the photon and
fermion pairs is calculated in the leading logarithmic approximation. It is
shown that this distribution function has a specific shape of a ``crest''. (To
be published in Mod.Phys.Lett.A)


title:
The radiative decay of a high energy neutrino in the Coulomb field of a
  nucleus

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 a
nucleus permit one to discuss the general possibility of carrying out a
neutrino experiment, subject to the condition of availability in the future of
a beam of neutrinos of these 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. (Published in
Phys.Lett.B 323 (1994) 179).


title:
Electromagnetic catalysis of the radiative transitions of $\nu_i
  \rightarrow \nu_j \gamma$ type in the field of an intense monochromatic wave

abstract:
  The radiative decay of the massive neutrino $\nu_i \rightarrow \nu_j \gamma$
in a circularly polarized electromagnetic wave is investigated within the
Standard theory with lepton mixing. The decay probability in the wave field
does not contain a threshold factor $\sim ( 1 - m_i / m_j )$ as opposed to the
decay probability in a vacuum or in a constant uniform external field. The
phenomenon of the gigantic enhancement ( $\sim 10^{33}$ ) of the neutrino decay
probability in external wave field is discovered. The probability of the photon
splitting into the neutrino pair is obtained. (Published in Phys.Lett.B 321
(1994) 108).


title: Exotic Searches

abstract:
  The experimental information on the search for non $q \bar q$ mesons as
glueballs, hybrids and multiquark states is reviewed. Candidate states which
are particularly amenable to detailed study by accumulating large samples of
$J/\psi$, $\eta_c$, $\chi$ decays at a $\tau$-charm factory are discussed.


title:
Next-to-Leading Order Debye-Screening in Spontaneously Broken Gauge
  Theories

abstract:
  The main role of the Debye screening mass in the perturbative treatment of
the electro-weak phase transition is the reduction of the cubic term that
determines the strength of a first-order transition. In this note I point out
that the standard definition of the Debye mass is unphysical. Its
next-to-leading order corrections in resummed perturbation theory are gauge
dependent generally in nonabelian gauge theories, and even in Abelian theories
when in the Higgs phase. A gauge independent definition can be obtained from a
gap equation for the propagator rather than the self-energy, which turns out to
be perturbatively under control in the Higgs phase, but sensitive to the
nonperturbative magnetic mass scale in the symmetric phase of nonabelian
theories. [Contributed talk at the NATO Advanced Research Workshop
``Electroweak Physics and the Early Universe'', 23 - 25 March 1994, Sintra,
Portugal]