title: Supersymmetric Electroweak Baryogenesis in the WKB approximation

abstract:
  We calculate the baryon asymmetry generated at the electroweak phase
transition in the minimal supersymmetric standard model, treating the particles
in a WKB approximation in the bubble wall background. A set of diffusion
equations for the particle species relevant to baryon generation, including
source terms arising from the CP violation associated with the complex phase
$\delta$ of the $\mu$ parameter, are derived from Boltzmann equations, and
solved. The conclusion is that $\delta$ must be $\gsim 0.1$ to generate a
baryon asymmetry consistent with nucleosynthesis. We compare our results to
several other recent computations of the effect, arguing that some are
overestimates.


title: A Model of Magnetic Monopoles

abstract:
  The possibility of the existence of magnetic charges is one of the greatest
unsolved issues of the physics of this century. The concept of magnetic
monopoles has at least two attractive features: (i) Electric and magnetic
fields can be described equivalently. (ii) In contrast to quantum
electrodynamics models of monopoles are able to explain the quantization of
electric charge. We suggest a quantum field theoretical model of the
electromagnetic interaction that describes electricity and magnetism as
equivalent as possible. This model requires the cross-section of Salam's
``magnetic photon'' to depend on the absolute motion of the electric charge
with which it interacts. We suggest a tabletop experiment to verify this
magnetic photon. Its discovery by the predicted effect would have far-reaching
consequences: (i) Evidence for a new gauge boson and a new kind of radiation
which may find applications in medicine. (ii) Evidence for symmetrized Maxwell
equations. (iii) Evidence for an absolute rest frame that gives rise to local
physical effects and violation of Einstein's relativity principle.

categories: hep-ph astro-ph hep-ex physics.optics quant-ph


title: m_u + m_d from QCD-Hadron Duality

abstract:
  The value of the light quark masses combination $m_u + m_d$ is analized using
QCD-Hadron Duality. A detailed analysis of both the perturbative QCD [to
four-loops] and the hadronic parametrization needed is done. The result we get
is $[m_u + m_d] (1 GeV^2) = (12.8 \pm 2.5)$ MeV ($[m_u + m_d] (4 GeV^2) = (9.8
\pm 1.9)$ MeV) in the $\barMS$ scheme.


title:
Explicit Quark-hadron Duality in Heavy-light Meson Weak Decays in the 't
  Hooft Model

abstract:
  We compute the nonleptonic weak decay width of a heavy-light meson in 1+1
spacetime dimensions with a large number of QCD colors (the 't Hooft model) as
a function of the heavy quark mass. In this limit, QCD is exactly soluble, and
decay modes are dominated by two-particle final states. We compare the results
to the tree-level partonic decay width of the heavy quark in order to test
quark-hadron duality in this universe. We find that this duality is
surprisingly well satisfied in the heavy quark limit, in that the difference
between the sum of exclusive partial widths and the tree-level partonic width
approaches a constant as M --> infinity, and the deviation is well-fit by a
small 1/M correction. We comment on the meaning of this conclusion and its
implications for the use of quark-hadron duality in hadronic physics.


title: CP Violation in Neutrinoless Double Beta Decay

abstract:
  We argue three-flavour neutrino mixing. We consider the neutrinos as Majorana
particles and see how the neutrinoless double beta decay constrains the
neutrino mixing angles. Our formulation is widely valid and is applied to the
neutrino oscillation experiment.


title:
The Role of the Vacuum Insertion Approximation in Calculating CP
  Asymmetries in B Decays

abstract:
  CP asymmetries in $B$ decays into final CP eigenstates are in many cases
theoretically clean. In particular, they do not depend on the values of
hadronic parameters. The sign of the asymmetries, however, does depend on the
sign of the $B_B$ parameter. Furthermore, the information from $\epsilon_K$
that all angles of the unitarity triangles lie in the range $\{0,\pi\}$ depends
on the sign of the $B_K$ parameter. Consequently, in the (unlikely) case that
the vacuum insertion approximation is such a poor approximation that either
$B_B$ or $B_K$ is negative, the sign of CP asymmetries in neutral $B$ decays
will be opposite to the standard predictions. Various subtleties concerning the
role of $K-\bar K$ mixing in the case of final states with a single $K_S$ or
$K_L$, such as the $B\to\psi K_S$ decay, are clarified.


title: Electroweak Baryogenesis in the Minimal Supersymmetric Standard Model

abstract:
  I describe work done in collaboration with M. Joyce and K. Kainulainen on (1)
the strength of the electroweak phase transition in the MSSM and (2) the
mechanism for producing the baryon asymmetry during the phase transition. In
the former we compare the effective potential and dimensional reduction methods
for describing the phase transition and search the parameter space of the MSSM
for those values where it is strong enough. In the latter we give a systematic
computation of the baryon asymmetry due the CP-violating force acting on
charginos in the vicinity of the bubble wall. We find that a light right-handed
stop, a light Higgs boson, and a large phase in the mu parameter, are the main
necessary ingredients for producing the baryon asymmetry.


title: Dynamically Broken Scale Invariance and Cosmology

abstract:
  A new scalar-tensor theory of gravity induced by dynamically broken scale
invariance is proposed, and its cosmological implications are discussed. It is
found that the model admits an inflation via the Hawking-Moss bubbling, but the
inflation rate remains undetermined due to the strong gravity limit. In light
of this, scale-invariant metric perturbations having a dominant tensor
component can be generated without slow-rollover. In addition, the deviation
from the standard hot big-bang is vanishingly small after inflation.


title: On the Finite Temperature Phase Transition of Scalar QED

abstract:
  We analyse the finite temperature phase transition of scalar QED in euclidean
spacetime. Analytical solutions of approximations to a Wilsonian
renormalisation group equation are discussed. Special emphasis is put on the
discussion of the $3d$ running of the Abelian charge and its effects on
thermodynamical quantities. An upper bound for the range of first-order phase
transitions is given. Our results are compared to those of resummed
perturbation theory.


title:
Probing Electroweak Symmetry Breaking via WW Interactions at High Energy
  Colliders

abstract:
  We classify the sensitivities of the future high energy hadron and electron
colliders, such as the LHC and the future Linear Colliders, to probing all the
next-to-leading order (NLO) bosonic operators for studying the electroweak
symmetry breaking (EWSB) mechanism. We first develop a power counting rule (a
generalization of Weinberg's counting method for the nonlinear sigma model) for
the electroweak theories formulated by the chiral Lagrangian. Then, we
formulate the Longitudinal-Goldstone Boson Equivalence Theorem as a physical
criterion to discriminate the scattering processes that are not sensitive to
the EWSB sector. The "complementarity" of different scattering processes via
different colliders for a complete probe of all these NLO effective operators
is demonstrated.


title:
Vacuum oscillations of solar neutrinos: correlation between spectrum
  distortion and seasonal variations

abstract:
  Long length vacuum oscillations solution of the solar neutrino problem is
discussed. We show that there is a strict correlation between a distortion of
the neutrino energy spectrum and an amplitude of seasonal variations of the
neutrino flux. The slope parameter which characterizes a distortion of the
recoil electron energy spectrum in the Super-Kamiokande experiment and the
seasonal asymmetry of the signal have been calculated in a wide range of
oscillation parameters. The correlation of the slope and asymmetry gives
crucial criteria for identification or exclusion of this solution. For the
positive slope indicated by preliminary Super-Kamiokande data we predict (40 -
60) % enhancement of the seasonal variations.


title: Summary, DIS 97

abstract:
  Some of the experimental and theoretical results discussed at the Fifth
International Workshop on Deep Inelastic Scattering and QCD are reviewed.


title: Top Quark Analysis in the Light Gluino Scenario

abstract:
  The Fermilab top quark analysis is heavily dependent on the assumption of
standard model backgrounds only. In the light gluino scenario, the stop quarks
lie near the top in mass and their decays can influence the resulting top quark
mass by an amount that is not small relative to the currently quoted errors.
Several slight anomalies in the top quark analysis find a natural explanation
in the light gluino case.


title: Seeding of Strange Matter with New Physics

abstract:
  At greater than nuclear densities, matter may convert into a mixture of
nucleons, hyperons, dibaryons, and strangelets, thus facilitating the formation
of strange matter even before the onset of the quark-matter phase transition.
From a nonstrange dibaryon condensate, it may even be possible to leapfrog into
strange matter with a certain new interaction, represented by an effective
six-quark operator which is phenomenologically unconstrained.


title: Revelations of the U(1)-Extended Supersymmetric Standard Model

abstract:
  If an extra supersymmetric U(1) gauge factor exists at the TeV energy scale,
which is then broken together with the supersymmetry, there will be several
interesting and important phenomenological consequences, not only at the TeV
scale, but also at the 100 GeV scale. For one, the generic two-doublet Higgs
structure will involve 3 additional parameters beyond that of the Minimal
Supersymmetric Standard Model (MSSM), thereby raising the upper bound on the
mass of the lighter of the two neutral Higgs scalars. For another, the
supersymmetric scalar quarks and leptons receive new contributions to their
masses from the spontaneous breaking of this extra U(1). Assuming a
grand-unified E_6 gauge symmetry and universal soft supersymmetry-breaking
terms at the grand-unification energy scale, we find solutions relating the
U(1) breaking scale and the ratio of the vacuum expectation values of the two
electroweak Higgs doublets.


title: Isolated Prompt Photon Production

abstract:
  We show that the conventionally defined partonic cross section for the
production of isolated prompt photons is not an infrared safe quantity. We work
out the case of $e^+e^- \to \gamma + X$ in detail, and we discuss implications
for hadron reactions such as $p \bar{p} \to \gamma + X$.


title:
The minimal supersymmetric standard model and precision of W-boson mass
  and top quark mass

abstract:
  We argue that the present value and accuracy of $M_W$ and $m_t$ measurements
tend to favor the MSSM over the SM. By speculating that a precision of the
order 40 MeV and 3 GeV respectively for $M_W$ and $m_t$ will be achieved at
LEP2 and Tevatron, we show that the prospect for the MSSM will be further
enhanced as long as the central values of $M_W$ and $m_t$ do not decrease below
the present values. In addition we discuss how this scenario can constrain the
Higgs boson mass and distinguish the Higgs boson of the MSSM type from that of
the SM.


title:
Anomalous D-term, dynamical supersymmetry breaking and dynamical gauge
  couplings

abstract:
  We analyze the structure of the vacuum and supersymmetry breaking pattern in
Fayet-Iliopoulos models with dynamical gauge coupling and planck-scale value of
the F-I parameter. We show that in this class of models supersymmetry is
generically broken, but the mere presence of the D-term is not sufficient to
stop the running away of the modulus responsible for the value of the gauge
coupling - the dilaton. To stabilize the dilaton, one has to include an
additional dilaton-dependent part in the superpotential. The presence of the
large D-term gives rise to the mixed dilaton/D-term dominated scenarios of susy
breaking, which allow horizontal hierarchy generation. Models which can serve
as secluded sectors in gauge mediation scenarios are discussed. It is shown
that when the F-I parameter and the gauge coupling are dynamical variables, the
D-term dominated Universe does not allow for an inflationary period.


title: The Sigma_c and Lamda_c magnetic moments from QCD spectral sum rules

abstract:
  We use QCD spectral sum rules to extract the Sigma_c and Lambda_c magnetic
moments. The elctromagnetic field is treated as the external field. We adopt
the value of the susceptibility chi=-4.5 GeV^{-2}, which is determined from an
overall analysis of the octet baryon magnetic moments. Our result for Sigma_c
is in agreement with the quark model prediction, while slight deviation exists
from the Lambda_c.


title: Cancellation of ladder graphs in an effective expansion

abstract:
  A resummation of ladder graphs is important in cases where infrared,
collinear, or light-cone singularities render the loop expansion invalid,
especially at high temperature where these effects are often enhanced. It has
been noted in some recent examples of this resummation that the ladder graphs
are canceled by other types of terms. In this note we show that this
cancellation is quite general, and for the most part algebraic.


title: Neutralino decay in the $\mu$-problem solvable extra U(1) models

abstract:
  We study the neutralino decay in the supersymmetric extra U(1) models which
can solve the $\mu$-problem. In these models the neutralino sector is extended
at least into six components by an extra U(1) gaugino and a superpartner of a
singlet Higgs. Focussing on its two lower mass eigenstates $\tilde\chi_2^0$ and
$\tilde\chi_1^0$, decay processes such as a tree level three body decay
$\tilde\chi_2^0\to \tilde\chi_1^0 f\bar f$ and a one-loop radiative decay
$\tilde\chi_2^0\to \tilde\chi_1^0\gamma$ are estimated. We investigate the
condition under which the radiative decay becomes the dominant mode and also
numerically search for such parameter regions. In this analysis we take account
of the abelian gaugino kinetic term mixing. We suggest that the gaugino mass
relation $M_W\sim M_Y$ may not be necessary for the radiative decay dominance
in the extra U(1) models.


title:
Generalized States for Multipion Production and Disoriented Chiral
  Condensates

abstract:
  We show that the sudden quenching mechanism responsible for the production of
the disoriented chiral condensate gives rise automatically to squeezed states.
We compare the distribution of charged and neutral pions in the two extreme
limits of a sudden quench and a slow adiabatic relaxation and show that in the
former case the difference in the distributions is much more dramatic than in
the latter. We also examine the isospin stucture of the resulting squeezed pion
distributions.


title: $\psi'$ productions as a test of color-octet mechanism

abstract:
  To test the color-octet model of heavy quarkonium productions, we propose
$\psi '$-productions at small-$p_T$ regions in polarized $pp$ collisions for
the forthcoming RHIC polarized experiments, whose experimental test at $\sqrt
s=50$ GeV might be very promising.


title: SM Higgs mass bounds from theory

abstract:
  The two-loop Higgs mass upper bounds are reanalyzed. Previous results for a
cutoff scale $\Lambda\approx$ few TeV are found to be too stringent. For
$\Lambda=10^{19}$ GeV we find $M_H < 180 \pm 4\pm 5$ GeV, the first error
indicating the theoretical uncertainty, the second error reflecting the
experimental uncertainty due to $ m_t = 175 \pm 6 $ GeV. We also summarize the
lower bounds on $M_H$. We find that a SM Higgs mass in the range of 160 to 170
GeV will certainly allow for a perturbative and well-behaved SM up to the
Planck-mass scale $\Lambda_{Pl}\simeq 10^{19}$ GeV, with no need for new
physics to set in below this scale.


title: SM Higgs decay and scattering processes at two loops

abstract:
  This contribution reviews the latest results of the perturbative calculations
of heavy-Higgs two-loop amplitudes. A comparison of perturbative results with
nonperturbative lattice calculations is made, and the theoretical uncertainties
of the lower and upper bound on the Standard Model Higgs mass are presented.


title: New Developments In Non-Hermitian Random Matrix Models

abstract:
  In this talk we go over several new developments regarding the techniques for
a large class of non-hermitian matrix models with unitary randomness (complex
random numbers). In particular, we discuss:
  (a) - A diagrammatic approach based on a $1/N$ expansion
  (b) - A generalization of the addition theorem (R-transformation)
  (c) - A conformal transformation on the position of pertinent singularities
  (d) - A `phase' analysis using appropriate partition functions
  (e) - A number of two-point functions and the issue of universality.


title: Don't Stop Thinking About Leptoquarks: Constructing New Models

abstract:
  We discuss the general framework for the construction of new models
containing a single, fermion number zero scalar leptoquark of mass $\simeq
200-220$ GeV which can both satisfy the D0/CDF search constraints as well as
low energy data, and can lead to both neutral and charged current-like final
states at HERA. The class of models of this kind necessarily contain new
vector-like fermions with masses at the TeV scale which mix with those of the
Standard Model after symmetry breaking. In this paper we classify all models of
this type and examine their phenomenological implications as well as their
potential embedding into SUSY and non-SUSY GUT scenarios. The general coupling
parameter space allowed by low energy as well as collider data for these models
is described and requires no fine-tuning of the parameters.


title:
Ultra-High Energy Neutrino-Nucleon Cross Section and Radiative
  Corrections

abstract:
  A cubic kilometer scale experiment has been proposed to detect cosmic
neutrinos of energy from tens of GeV up to the highest energies observed for
cosmic rays, around 10**20 eV, or possibly even beyond. Detection efficiencies
depend crucially on the neutrino-nucleon cross section at these energies at
which radiative corrections beyond the lowest order approximation could become
non-negligible. The differential cross sections can be modified by more than
50% in some regions of phase space. Estimates of corrections to the quantities
most relevant for neutrino detection at these energies give, however, less
dramatic effects: The average inelasticity in the outgoing lepton is increased
from about 0.19 to 0.24. The inclusive cross section is reduced by roughly half
a percent. The dominant uncertainty of the standard model ultra-high energy
neutrino-nucleon cross section therefore still comes from uncertainties of the
parton distributions in the nucleon at very low momentum fractions.


title: SUSY charged Higgs boson pair production via gluon-gluon collisions

abstract:
  The production of charged Higgs boson pairs from gluon-gluon fusion is
studied in the minimal supersymmetric model(MSSM) at proton-proton colliders.
We find that the contribution of the scalar quark loops to the subprocess
production rate is substantial and consequently the production rate in
proton-proton colliders is enhanced in the MSSM if there exist scalar quarks
with favorable masses. The results show that this cross section may reach a few
femptobarn in the future LHC collider with plausible values of the parameters.


title: Multiple soft pion production within nonlinear chiral sigma model

abstract:
  Multiple soft pion production in the baryon scattering reactions is
considered in the framework of chiral nonlinear sigma model neglecting the pion
mass. Treating baryons in the eikonal approximation as classical sources, a set
of analytical solutions for the pion field is found. A tree S-matrix is
constructed on the basis of these solutions describing the emission (or
absorption) of any number of soft pions. Then the contribution of soft virtual
pions is taken into account in a closed form. It is shown that the loop
corrections strongly suppress the pion radiation, and for the two limiting
cases of nonrelativistic and ultra-relativistic baryon scatterings there is no
pion emission from the "ends". Thus, the mechanism similar to the soft photon
bremsstrahlung in the quantum electrodynamics seems to be unable to create a
state with a large number of the soft pions.


title:
Asymptotic Expansions of Feynman Integrals on the Mass Shell in Momenta
  and Masses

abstract:
  A brief review of recent results on asymptotic expansions of Feynman
integrals on the mass shell in momenta and masses and their application to
2-loop calculations is presented.


title: QCD at large and short distances

abstract:
  The formulation of QCD which contains no divergences and no renormalization
procedure is presented. It contains both perturbative and non-perturbative
phenomena. It is shown that, due to its asymptotically free nature, the theory
is not defined uniquely. The chiral symmetry breaking and the nature of the
octet of pseudo-scalar particles as quasi-Goldstone states are analysed in the
theory with massless and massive quarks. The U(1) problem is discussed.


title: Effective Quark Interactions and QCD-Propagators

abstract:
  We compute the momentum dependence of the effective four quark interaction in
QCD after integrating out the gluons. Our method is based on a truncation of
exact renormalization group equations which should give reasonable results for
momenta above the confinement scale. The difference between the four quark
interaction and the heavy quark potential can be minimized for an optimal
renormalization scheme in Landau gauge. Within the momentum range relevant for
quarkonia our results agree with phenomenological potentials. We also calculate
the propagators for gluons and ghosts in Landau-gauge.


title: Foam Diagram Summation at Finite Temperature

abstract:
  We show that large-$N$ $\phi ^4$ theory is not trivial if one accepts the
presence of a tachyon with a truly huge mass, and that it allows exact
calculation. We use it to illustrate how to calculate the exact resummed
pressure at finite temperature and verify that it is infrared and ultraviolet
finite even in the zero-mass case. In 3 dimensions a residual effect of the
resummed infrared divergences is that at low temperature or strong coupling the
leading term in the interaction pressure becomes independent of the coupling
and is 4/5 of the free-field pressure. In 4 dimensions the pressure is
well-defined provided that the temperature is below the tachyon mass. We
examine how rapidly this expansion converges and use our analysis to suggest
how one might reorganise perturbation theory to improve the calculation of the
pressure for the QCD plasma.


title: Numerical simulations of string networks in the Abelian-Higgs model

abstract:
  We present the results of a field theory simulation of networks of strings in
the Abelian Higgs model. Starting from a random initial configuration we show
that the resulting vortex tangle approaches a self-similar regime in which the
length density of lines of zeros of $\phi$ reduces as $t^{-2}$. We demonstrate
that the network loses energy directly into scalar and gauge radiation. These
results support a recent claim that particle production, and not gravitational
radiation, is the dominant energy loss mechanism for cosmic strings. This means
that cosmic strings in Grand Unified Theories are severely constrained by high
energy cosmic ray fluxes: either they are ruled out, or an implausibly small
fraction of their energy ends up in quarks and leptons.


title: Negative coupling instability and grandunified baryogenesis

abstract:
  I review my recent work with Brian Greene and Thomas Roos. First I discuss
the effect of a negative cross-coupling on the inflaton decay in two scalar
field theories. Our main finding is a new effect, the negative coupling
instability, which leads to explosive particle production and very fast
inflaton decay. Then I discuss the consequences of this instability for
grandunified baryogenesis models. The novel aspect of this review is an
intuitive explanation of the negative coupling instability, using field
trajectories in the configuration space.


title: Massive Neutrinos and Lepton Mixing in Unified Theories

abstract:
  The recent GUT (x SUSY) models which can predict the neutrino properties are
reviewed.


title: Heavy Quarks in Polarized Structure Functions

abstract:
  Quark mass effects are included in the calculation of polarized structure
functions. In particular, the validity of fixed order perturbation theory and
of massless evolution is studied in the framework of heavy quarks structure
functions. The polarized version of the ACOT and MRRS interpolating schemes for
the evolution of massive quarks distributions is also developed and studied.
The different behaviours of the various approaches in $x$ and $Q^2$ are shown.


title: Linear Sigma Model Linkage with Nonperturbative QCD

abstract:
  Linkage is demonstrated between the quark mass, quark condensate and coupling
strength in the infrared limit of QCD and in the quark-level linear sigma
model.


title:
Quenched and Partially Quenched Chiral Perturbation Theory for Vector
  and Tensor Mesons

abstract:
  Quenched and partially quenched chiral perturbation theory for vector mesons
is developed and is used to extract chiral loop correction to the $\rho$ meson
mass. Connections to fully quenched and totally unquenched chiral perturbation
theory results are discussed. It is also shown that (partially) quenched
perturbation theory for tensor mesons can be formulated analogously, and the
chiral corrections for tensor meson masses are directly proportional to their
counterparts in the vector meson sector. Utilizing this observation and
non-relativistic quark model, we point out that mass difference $(m_{a_2} - {3
\over 2} m_\rho)$ is ``quenching-insensitive'' in large-$N_c$ limit. This
quantity may be used for normalization of mass scale in lattice QCD
calculations.


title: H-dibaryon matter in the Skyrme model on a hypersphere

abstract:
  We study the properties of H-dibaryon matter through the SO(3) Skyrmion
solution on a three-dimensional hypersphere $S^3$. As the density increases,
the swelling of H-dibaryon is found. Above a critical density, the system
becomes uniform in terms of the baryon density. In this uniform phase, the
critical order parameter is largely reduced, which can be interpreted as the
chiral symmetry restoration. From the comparison with the $SO(2) \times SO(2)$
solution, the SO(3) soliton is found to be the true ground state for high
density system with $R \leq 0.64$ fm in the B=2 sector with $N_f=3$.


title: One-loop self energies at finite temperature

abstract:
  The complete one-loop self energies (real and imaginary parts) for photons,
gluons, electrons and quarks at finite temperature are calculated numerically
and compared to the results of the hard thermal loop (HTL) approximation used
for the resummation technique of Braaten and Pisarski. In this way some light
is shed on the validity of the weak coupling limit assumption ($g \ll 1$) or
equivalently the high temperature assumption, on which the HTL approximation is
based. Furthermore, the gauge dependence of the fermion self energy beyond the
HTL approximation is considered. Finally the dispersion relations following
from the real part of the self energies are compared to the HTL results.


title:
Renormalisation and power counting in effective field theories for
  nucleon-nucleon scattering

abstract:
  The renormalisation of NN scattering in theories with zero-range interactions
is examined using a cut-off regularisation and taking the cut-off to infinity.
Inclusion of contact interactions that depend on energy as well as momentum
allows the effective range to be fitted to experiment with any desired sign or
magnitude. However, power counting breaks down: terms of different orders in
the potential can contribute to the scattering amplitude at the same order.


title: Scaling of Z' limits at the Linear Collider

abstract:
  Z' exclusion limits and errors of Z' model measurements are compared for
different reactions at future linear colliders. The influence of the c.m.
energy, integrated luminosity, beam polarization and systematic errors is
discussed. The sensitivity to a Z' depends only on the product Ls and not on
the integrated luminosity and the c.m. energy separately.


title: HERA Data and Leptoquarks in Supersymmetry

abstract:
  I present a concise review of the possible evidence for new physics at HERA
and of the recent work towards a theoretical interpretation of the signal. It
is not clear yet if the excess observed at large Q^2 is a resonance or a
continuum (this tells much about the quality of the signal). I discuss both
possibilities. For the continuum case one considers either modifications of the
quark structure functions or contact terms. In the case of a resonance, a
leptoquark, the most attractive possibility that is being studied is in terms
of s-quarks with R-parity violation. In writing this script I updated the
available information to include the new data and the literature presented up
to August 1, 1997.


title:
Corrections to oblique parameters induced by anomalous vector boson
  couplings

abstract:
  We study quadratically divergent radiative corrections to the oblique
parameters at LEP1 induced by non-standard vector boson self-couplings. We work
in the Stueckelberg formalism and regulate the divergences through a
gauge-invariant higher derivative scheme. Using consistency arguments together
with the data we find a limit on the anomalous magnetic moment Delta kappa of
the W-boson, |Delta kappa| <= 0.26.


title: Resummation of next-to-leading logarithms in top quark production

abstract:
  We discuss the resummation of next-to-leading logarithms (NLL) in heavy quark
production near threshold. Results are presented for top quark production at
the Fermilab Tevatron.


title: Symmetry Breaking in $[SU(6)]^3\times Z_3$

abstract:
  We analize the different ways for the spontaneous breaking of the gauge
symmetry, for the $[SU(6)]^3\otimes Z_3$ family unification model. In
particular we study the consequences of a previous selection for the vacuum
expectation values of the Higgs fields, showing that such set predicts unwanted
flavor changing neutral currents at the $m_Z=91 GeVs$ mass scale. A new set of
vacuum expectation values which solves this problem is proposed.


title: One Step Non SUSY Unification

abstract:
  We show that it is possible to achieve one step gauge coupling unification in
a general class of non supersymmetric models which at low energies have only
the standard particle content and extra Higgs fields doublets. The constraints
are the experimental values of $\alpha_{em}$, $\alpha_s$ and $\sin^2\theta_W$
at $10^2 GeVs$, and the lower bounds for FCNC and proton decay rates. Specific
example are pointed out.


title:
Higgs Searches at Future Colliders: Potentials for Discovery and
  Diagnosis

abstract:
  The prospects for Higgs boson discovery and study at present and future
colliders are reviewed, with emphasis on the Minimal Supersymmetric Standard
Model (MSSM) states. The expected experimental coverages with different
production and decay modes are outlined. Particular attention is given to the
Higgs couplings predicted when the top quark Yukawa coupling has an infrared
fixed point. Characteristic Higgs boson mass spectra from the minimal
supergravity (mSUGRA) model are considered and the decoupling/non-decoupling
regimes of the lightest Higgs boson are discussed. General tests are described
to ascertain whether a discovered light Higgs boson is a SM or MSSM state and
to diagnose its fundamental properties. The constraints on the Higgs mass
spectra implied by an interesting cosmological relic density of the lightest
supersymmetric particle are described.


title: New Higgs Interactions in ZZ\gamma and Z\gamma\gamma Production

abstract:
  The effect of new operators that only modify the bosonic couplings of the
Higgs boson, without altering the WW\gamma or WWZ three-point functions, are
examined in the e+e- -> ZZ\gamma and Z\gamma\gamma processes. We analyse the
constraints on these interactions that can be imposed by the LEP II collider at
CERN and at the Next Linear Collider.


title: Next to Minimal Higgs : Mass Bounds and Search Prospects

abstract:
  The Standard Model of electroweak interactions has one scalar doublet. The
minimal extension of this sector is effected by adding a neutral, singlet
scalar field. Depending on whether the singlet field has a non-zero vacuum
expectation value, x, or not, the scenario has quite distinctive predictions.
In particular, x unequal to 0 produces a mixing between the usual SU(2) doublet
and the singlet, giving rise to two physical states and a goldstone boson with
non-vanishing coupling to these. Presence of this coupling modifies the 2 jets
+ missing energy signal of the Bjorken process at LEP. We update the bounds on
the Higgs mass using the LEP-1 data. We then explore, using parton-level Monte
Carlo event generators, the production of these scalars at the LHC via
gluon-gluon fusion and subsequent detection. We compare the signals with the
expected backgrounds.


title:
Concerning the Differences Between Zero Mass Dirac and Zero Mass
  Majorana Neutrinos

abstract:
  A physical difference between Majorana neutrinos and Dirac neutrinos (which
persists in the zero mass limit) is proved in two sentences.


title:
CP violation in the $\mu \to 3e$ process and supersymmetric grand
  unified theory

abstract:
  A triple vector correlation in the $\mu^{+} \to e^{+} e^{+} e^{-}$ decay with
polarized muons is investigated as a probe to CP violating coupling constants
in supersymmetric models. A sizable triple correlation can be induced due to a
complex phase in the supersymmetric soft-breaking terms in the SU(5) grand
unified theory. Correlation with the electric dipole moments of electron and
neutron are investigated and it is shown that these quantities give independent
information on possible CP violating sources.


title: Semileptonic B decay as a test of CKM unitarity

abstract:
  I point out that $B \to X_q \l^+ \l^-$ decays $(q = s, d)$ are sensitive
probes of possible violation of CKM unitarity. I compute the decay rates and
asymmetries in a minimal extension of the Standard Model containing an
additional isosinglet charge (-1/3) quark, which leads to a deviation from CKM
unitarity. It is shown that even for small mixing ratios
$|{z_{qb}}/{(V_{tq}^\ast V_{tb})}| \sim O({10}^{-2})$, the contribution of the
tree-level $Z-$FCNC appearing in the model should change the rates and
asymmetries significantly. Especially the CP asymmetry, $A_{CP} (B \to X_s \l^+
\l^-)$, can be enhanced to be few percents, while in the standard model the
size is less than $O({10}^{-3})$. On the other hand, $A_{CP} (B \to X_d \l^+
\l^-)$ is not altered so much. Constraints for the mixing ratios are extracted
from the experiments of $B \to X_s \gamma$ for $q = s$ and $B_d^0 -
\bar{B}_d^0$ mixing for $q = d$ under a natural assumption that the couplings
of the tree-level $Zf\bar{f}$ are almost unity, i.e. $z_{\alpha \alpha} \sim
1$.


title: Bound states of heavy quarks in QCD

abstract:
  Bound states of heavy $\bar{q}q$ quarks are reviewed within the context of
QCD, paying attention to what can be derived from the theory with a reasonable
degree of rigour. This is compared with the results of semiclassical arguments.
Among new results, we report a very precise $O(\alpha_s^4)$ evaluation of $b,
c$ quark masses from quarkonium spectrum with a potential to two loops.


title: Applications of Effective Lagrangians

abstract:
  Effective Lagrangians were originally used only at the tree level as
so-called phenomenological Lagrangians since they were in general
non-renormalizable. Today they are treated as effective field theories valid
below a characteristic energy scale. Quantum corrections can then be calculated
in a consistent way as for any renormalizable theory. A few applications of the
Euler-Heisenberg Lagrangian for interacting photons at low energies are
presented together with recent developments in the use of QED for
non-relativistic systems. Finally, the ingredients of an effective theory for
the electroweak sector of the Standard Model are discussed in the case of a
non-linear realization of the Higgs mechanism using the Stuckelberg formalism.
[Invited talk at "Beyond the Standard Model V", Balholm, Norway, April 29 - May
4, 1997]


title:
Radiative corrections to the differential decay rate of polarized
  orthopositronium

abstract:
  The order - \alpha radiative corrections to the differential decay rate of
polarized orthopositronium are obtained. Their influences on the three photons
coincidence rate as a function of positronium polarization is considered.


title: Seeing Planck Scale Physics At Accelerators

abstract:
  Much curent theoretical analysis is based on the hypothesis that the physics
beyond the Standard Model is a consequence of new principles that occur at the
Planck scale. The question arises whether such principles can ever be directly
tested. We show here that for a significant class of models, hypotheses made at
the string or Planck scale can indeed be directly tested to a relatively high
degree of precision by linear colliders. Three classes of models are examined:
those with universal SUSY soft breaking at the string scale, those with a
horizontal symmetry at the string or Planck scale, and simple Calabi-Yau
superstring models with dilaton and moduli SUSY breaking. (Invited talk at
Orbis97.)


title: Charm Production in Deep Inelastic Lepton-Hadron Scattering

abstract:
  A review is given of the QCD corrections to charm quark production in deep
inelastic electron-proton scattering. An outline of the computation of the
virtual photon-parton subprocesses, from which one obtains the heavy quark
coefficient functions, is given. The dominant production mechanisms are
discussed. Further we show that the asymptotic heavy quark coefficient
functions, computed in the limit Q^2 >> m^2, can be derived using the operator
product expansion technique. Further we present the various schemes proposed in
the literature to describe the charm component of the structure function and
compare them with the most recent data from the experiments carried out at
HERA.


title: Low Energy Grand Unification With SU(16)

abstract:
  We study the possibility of achieving low unification scale in a grand
unification scheme based on the gauge group SU(16). Baryon number symmetry
being an explicit local gauge symmetry here gauge boson mediated proton decay
is absent. We present in detail a number of symmetry breaking patterns and the
higgs field representations giving rise to the desired symmetry breakings and
identify one chain giving low energy unification. These higgs field
representations are constructed in such a way that higgs mediated proton decay
is absent. At the end we indicate the very rich low energy physics obtainable
from this model which includes quark-lepton un-unified symmetry and chiral
color symmetry. In brief some phenomenological implications are also studied.


title: QCD Sum Rules and the Pi(1300) Resonance

abstract:
  Global fits to the shape of the first QCD Laplace sum rule exhibiting
sensitivity to pion-resonance [$\Pi (1300)$] parameters are performed, leading
to predictions for the pion-resonance mass and decay constant. Two scenarios
are considered which differ only in their treatment of the dimension-six quark
condensate $< O_6>$. The first scenario assumes an effective scale for $< O_6>$
from other sum-rule applications which is assumed to be independent of the
physical value of the quark mass, while the second scenario requires
self-consistency between the value of $< O_6>$ and the current algebra
constraint $2m< \bar q q>=-f_\pi^2m_\pi^2$. Predictions of the pion-resonance
mass $M_\pi$ and decay constant $F_\pi$ are obtained in these two scenarios. A
byproduct of this analysis is a prediction of the renormalization-group
invariant quark mass $(\hat m_u+\hat m_d)/2$.


title: MSSM Higgs searches in multi-b-jet final states at the LHC

abstract:
  This paper discusses the possibility to observe a signal from MSSM Higgs
boson decays into final states containing four b-jets. Two specific channels
are considered: bbH and bbA production with H,A -->bb, for large values of mH,
mA and tan(beta), and H-->hh-->bbbb decays for 150 GeV < mH < 2 and for low
values of tan(beta). Both channels are difficult to extract because of the very
large reducible and irreducible QCD backgrounds. Even with an ultimate
integrated luminosity, expected per LHC experiment, of 3*10**5 pb**-1, the
region of the MSSM parameter space covered by these channels does not extend
the reach beyond that accessible to other channels that were studied in the
past. Nevertheless, their observation would help in constraining the couplings
and branching ratios of the MSSM Higgs bosons.


title:
The Neutron and the Electron Electric Dipole Moment in N=1 Supergravity
  Unification

abstract:
  An analysis of the neutron EDM and of the electron EDM in minimal N=1
supergravity unification with two CP violating phases is given. For the neutron
the analysis includes the complete one loop gluino, chargino, and neutralino
exchange diagrams for the electric dipole and the chromoelectric dipole
operators, and also the contribution of the purely gluonic dimension six
operator. It is shown that there exist significant regions in the six
dimensional parameter space of the model where cancellations between the gluino
and the chargino exchanges reduce the electric and the chromoelectric
contributions, and further cancellations among the electric, the
chromoelectric, and the purely gluonic parts lead to a dramatic lowering of the
neutron EDM sometimes below the electron EDM value. This phenomenon gives a new
mechanism, i.e., that of internal cancellations, for the suppression of the
neutron EDM in supersymmetric theories. The cancellation mechanism can
significantly reduce the severe fine tuning problem associated with CP
violating phases in SUSY and SUGRA unified models.


title:
New Regularization-Renormalization Method in Quantum Electrodynamics and
  Qualitative Calculation on Lamb Shift

abstract:
  A simple but effective method for regularization-renormalization (R-R) is
proposed for handling the Feynman diagram integral (FDI) at one loop level in
quantum electrodynamics (QED). The divergence is substituted by some constants
to be fixed via experiments. So no counter term, no bare parameter and no
arbitrary running mass scale is involved. Then the Lamb Shift in Hydrogen atom
can be calculated qualitatively and simply as $\Delta E(2S_{1/2})- \Delta
E(2P_{1/2})=996.7 MHz$ versus the experimental value $1057.85 MHz$.


title: Partonometry in W + jet production

abstract:
  QCD predicts soft radiation patterns that are particularly simple for $W+
{jet}$ production. We demonstrate how these patterns can be used to distinguish
between the parton-level subprocesses probabilistically on an event-by-event
basis. As a test of our method we demonstrate correlations between the soft
radiation and the radiation inside the outgoing jet.


title: Testing Parton Charge Symmetry at HERA

abstract:
  There are strong theoretical indications that the minority valence quark
distributions in the nucleon may break charge symmetry by as much as 3-5%. We
show that a comparison of $e^{\pm} D$ deep inelastic scattering through the
charged current, for example at HERA, could provide a direct test of this
effect. This measurement is also be sensitive to an intrinsic component of the
strange quark sea which leads to $s \neq \bar{s}$.


title: A Numerical Study of an Expanding Plasma of Quarks in a Chiral Model

abstract:
  We numerically solve the transport equations for a quark gas described by the
the Nambu-Jona-Lasinio model. The mean field equations of motion, which consist
of the Vlasov equation for the density and the gap equation for the mean field,
are discussed, and energy and momentum conservation are proven. Numerical
solutions of the partial differential equations are obtained by applying finite
difference methods. For an expanding fireball of the light quark mass evolves
from small values initially to the value of 350 MeV. This leads to a depletion
of the high energy part of the quark spectrum and an enhancement at low
momenta. When collisions are included one obtains an equation of the Boltzmann
type, where the transition amplitudes depend on the properties of the medium.
These equations are given for flavor SU(3), i. e. including strangeness. They
are solved numerically in the relaxation time approximation and the time
evolution of various observables is given. Medium effects in the relaxtion
times do not significantly influence the shape of the spectra. The mass of the
strange quark changes little during the expansion. The strangeness yield and
the slope temperatures of the final spectra are studied as a function of the
size of the initial fireball.


title: Analytical continuation and resummed perturbation theory

abstract:
  A pattern of partial resummation of perturbation theory series inspired by
analytical continuation is discussed for some physical observables.


title: On e+e- to W+W- at LEP2

abstract:
  We briefly discuss the first direct experimental evidence from LEP2 on
non-vanishing trilinear couplings among the weak vector bosons. Subsequently we
review the improved Born approximation to include radiative corrections.
Provided the appropriate high-energy scale is used for the SU(2)
gauge-coupling, the improved Born approximation is sufficiently accurate for
all practical purposes at LEP2.


title: Colour reconnection and Bose-Einstein effects

abstract:
  Final-state interactions and interference phenomena that could affect the
value of the W mass reconstructed from hadronic WW decays at LEP2 are reviewed,
and possible areas for future investigation are identified.


title: Hard underlying event correction to inclusive jet cross sections

abstract:
  Jets observed in hadron-hadron scattering contain a contribution from the
underlying event that is produced by spectator interactions taking place
incoherently with the major parton-parton collision, due to the extended
composite structure of the colliding hadrons. Using a recent measurement of the
double parton interaction rate, we calculate that the underlying event may be 2
- 3 times stronger than generally assumed, as a result of semi-hard
perturbative multiple-parton interactions. This can have an important influence
on the inclusive jet cross section at moderate values of E_T, persisting at the
5 - 10% level to the largest observable E_T. We show how the underlying event
can be measured accurately using a generalization of the method first proposed
by Marchesini and Webber.


title: Limits on leptonic photon interactions from SN1987a

abstract:
  If massless leptonic photons associated to electron, muon or tau leptonic
number exist they would have been emitted from supernova 1987a via the
annihilation process $\nu\bar{\nu}\to\gamma_{l}\gamma_{l}$. By requiring that
this process does not carry away most of the energy that can be radiated by the
supernova we obtain an upper limit on the leptonic photon coupling constants,
$\alpha_{l} < 5.4 \times 10^{-11}$. Under certain assumptions about
$\gamma_{l}$ - trapping conditions we find that the region of $\alpha_{l} =
10^{-8} - 10^{-7}$ might be of interest for an experimental search for leptonic
photons.


title: QCD Sum Rules and the Lowest-Lying I=0 Scalar Resonance

abstract:
  A QCD Laplace sum rule framework is employed to investigate the relationship
between the mass and the decay width of the sigma, the lowest-lying isoscalar
resonance in the spin-zero meson channel. Our analysis differs from prior
analyses, not only by incorporating finite-width departures from the narrow
resonance approximation, but also through the inclusion of direct-instanton
contributions and three-loop-order perturbative effects. Assuming that the
sigma is the dominant subcontinuum resonance in this channel, the least upper
bound we obtain for the sigma-mass is shown to increase with the sigma-width,
and suggests that a sigma lighter than 800 MeV should have a total width
substantially smaller than its mass.


title: Determination of \alpha_s from Event Shapes and Power Corrections

abstract:
  The size of non-perturbative corrections to event shape observables is
predicted to fall like a power of the inverse centre of mass energy. These
power corrections are investigated for different observables from
e+e-annihilation and compared to the theoretical predictions. Using the latest
DELPHI high energy data advantages of determining \alpha_s from these
predictions are discussed and compared to conventional methods.


title: New Quadratic Mass Relations for Heavy Mesons

abstract:
  By assuming the existence of (quasi)-linear Regge trajectories for heavy
mesons, we derive new quadratic mass relations of non-Gell-Mann-Okubo type,
6M^2(q-qbar)+3M^2(c-cbar)=8M^2(c-qbar), 20M^2(q-qbar)+5M^2(b-bbar)=
16M^2(b-qbar), q=n(=u,d),s, which show excellent agreement with experiment. We
also establish the sum rule M^2(i-ibar)+M^2(j-jbar)-2M^2(j-ibar)\approx const
for any pair of flavors, (i,j).


title: Nucleon Instability in SUSY Models

abstract:
  A review of the current status of nucleon stability in SUSY unified models is
given. The review includes analysis of nucleon stability in the minimal SU(5)
supergravity model, and in extensions of the minimal model such as SO(10)
models, and models including textures. Implications of the simultaneous
constraint of the experimental limit on the proton lifetime and the constraint
that dark matter not overclose the universe are also discussed.


title:
Toward loop level study of supersymmetric models at future e^+e^- linear
  colliders

abstract:
  In the case with a large splitting between the squark and slepton masses, the
supersymmetric identities which enforce the equality of the gauge and gaugino
couplings are violated in the effective theory below the squark mass threshold.
We compute the full one-loop (s)quark corrected slepton production
cross-sections. We find that the one-loop corrected slepton production
cross-sections can depend on the squark mass strongly, up to 9%
*log_{10}(M_{\tilde{Q}}/m_{\tilde{l}}). We investigate the squark mass
sensitivity of the slepton cross-section measurements at a future linear
collider. For sneutrino production accessible at \sqrt{s}=500 GeV there can be
sensitivity to squark masses at or larger than 1 TeV.


title: String derivation of two-loop Feynman diagrams

abstract:
  We briefly review the technology involved in extracting the field-theory
limit of multiloop bosonic string amplitudes, and we apply it to the evaluation
of simple two-loop diagrams involving scalars and gauge bosons.


title:
Pre-thermalization dynamics: initial conditions for QGP at the LHC and
  RHIC from perturbative QCD

abstract:
  I discuss how the initial conditions for QGP-production in ultrarelativistic
heavy ion collisions at the LHC and RHIC can be computed from perturbative QCD.


title: Isospin constraints on the $\tau\to K\bar Kn\pi\nu$ decay mode

abstract:
  The construction of the complete isospin relations and inequalities between
the possible charge configurations of a $\tau\to K\bar Kn\pi\nu$ decay mode is
presented. Detailed applications to the cases of two and three pions are given.


title: Angular ordering and structure functions at small x

abstract:
  We examine the effect of using an angular ordered evolution equation for the
unintegrated gluon distribution at small x.


title:
The electroweak phase structure and baryon number violation for large
  Higgs mass

abstract:
  The classical transitions between topologically distinct vacua in a
SU(2)-Higgs model, using a Higgs field of mass approximately 120 GeV, is
examined to probe the crossover region between the symmetric and broken phase.
For the volumes used, this crossover is approximately 10 GeV wide.


title: New Physics and the Unitarity Triangle

abstract:
  After reviewing the present experimental constraints on the unitarity
triangle, I discuss the various ways in which new physics can manifest itself
in measurements of the parameters of the unitarity triangle. Apart from one
exception, which I describe, new physics enters principally through new
contributions to B0-B0(bar) mixing. Different models of new physics can be
partially distinguished by looking at their effects on rare, flavour-changing
$B$ penguin decays. (Invited talk given at the Symposium Twenty Beautiful Years
of Bottom Physics, Chicago, IL, USA, June 29 -- July 2, 1997.)


title:
Estimate of the long-distance contribution through b --> s \psi to the
  B_{s} --> \gamma\gamma decay rate

abstract:
  The B_{s} --> \phi\psi decay is modeled through the inclusive b --> s\psi
decay. Using the Vector Meson Dominance model, the amplitude for the chain
process B_{s} --> \phi\psi --> \phi\gamma --> \gamma\gamma is estimated and it
is found to be at most 4 % of the corresponding amplitude from the O_7 type LD
contribution. The intermediate amplitude for the process B_{s} --> \phi\gamma
is compared with the corresponding one obtained by a different approach based
on the interaction of the virtual charm quark loop with soft gluons
\cite{Ruckl}. Both amplitudes are found to agree within 10 %. Further the
influence on the branching ratio B(B_{s} --> \gamma\gamma)_{SD+LD_{O7}} from
inclusive b --> s \psi is estimated as less than 1 %.


title: Two Photon Physics at LEP2

abstract:
  The working group on two photon physics concentrated on three main subtopics:
modelling the hadronic final state of deep inelastic scattering on a photon;
unfolding the deep inelastic scattering data to obtain the photon structure
function; and resonant production of exclusive final states, particularly of
glueball candidates. In all three areas, new results were presented.


title: Polarised and Unpolarised Charmonium Production at Higher Orders in v

abstract:
  We study the unpolarised and polarised hadro-production of charmonium in
non-relativistic QCD (NRQCD) at low transverse momentum, including sufficiently
higher orders in the relative velocity, $v$, so as to study the ratio of
$\chi_{c1}$ and $\chi_{c2}$ production rates.


title: On the Analytic "Causal" Model for the QCD Running Coupling

abstract:
  We discuss the model $\bar{\alpha}_{an}(Q^2)$ recently proposed for the QCD
running coupling $\bar{\alpha}_s(Q^2)$ in the Euclidean domain on the basis of
the "asymptotic-freedom" expression and on causality condition in the form of
the $Q^2$-analyticity. The model contains no adjustable parameters and obeys
the important features: (i) Finite ghost-free behavior in the "low $Q^2$"
region and correspondence with the standard RG-summed UV expressions;%\item~ %
(ii) The universal limiting value $\bar{\alpha}_{an}(0)$ expressed only via
group symmetry factors. This value as well as the $\bar{\alpha}_{an}$ behavior
in the whole IR region $Q^2 \leq \Lambda^2$ turns out to be stable with respect
to higher loop corrections; %\item~ (iii) Coherence between observed
$\bar{\alpha}_s(M_{\tau}^2)$ value and integral information on the IR
$\bar{\alpha}_s(Q^2)$ behavior extracted from jet physics.


title: Spin Correlations in Production and Subsequent Decay of Neutralinos

abstract:
  We study the process e^{-} e^{+} -> chi^0_1 chi^0_2 with the subsequent decay
chi^0_2 -> chi^0_1 l^{+} l^{-} taking into account the complete spin
correlations. We give the analytical formulae for the differential cross
section and present numerical results for the lepton angular distribution and
the distribution of the opening angle between the outgoing leptons for the LEP2
energy of sqrt{s}=193 GeV and for sqrt{s}=500 GeV. We examine three
representative mixing scenarios in the MSSM and also study the influence of the
common scalar mass parameter m_0 on the shape of the distributions. For the
lepton angular distribution the effect of the spin correlations amounts to up
to 20% for lower energies. We find that the opening angle distribution is
suitable for distinguishing between higgsino-like and gaugino-like neutralinos.
The shape of the lepton angular distribution is very sensitive to the mixing in
the gaugino sector and to the value of m_0. For higher energies it is also
suitable for distinguishing between higgsino-like and gaugino-like neutralino.


title: A Tale of Three Equations: Breit, Eddington-Guant, and Two-Body Dirac

abstract:
  G.Breit's original paper of 1929 postulates the Breit equation as a
correction to an earlier defective equation due to Eddington and Gaunt,
containing a form of interaction suggested by Heisenberg and Pauli. We observe
that manifestly covariant electromagnetic Two-Body Dirac equations previously
obtained by us in the framework of Relativistic Constraint Mechanics reproduce
the spectral results of the Breit equation but through an interaction structure
that contains that of Eddington and Gaunt. By repeating for our equation the
analysis that Breit used to demonstrate the superiority of his equation to that
of Eddington and Gaunt, we show that the historically unfamiliar interaction
structures of Two-Body Dirac equations (in Breit-like form) are just what is
needed to correct the covariant Eddington Gaunt equation without resorting to
Breit's version of retardation.


title: A study of the scenario with nearly degenerate Majorana neutrinos

abstract:
  Motivated by cosmological considerations, and by the atmospheric and solar
neutrino flux deficits, we consider the scenario in which the three Standard
Model neutrinos are endowed with a nearly equal Majorana mass in the eV range.
Combined constraints coming from (1) direct search for electron neutrino mass,
(2) absence of neutrinoless double beta decay, and (3) unsuppressed electron
neutrino flux in present reactor experiments, imply a quite well specified
pattern of neutrino masses and mixing angles. We discuss the experimental tests
of the model and comment on the features of this scenario.


title: Deuteron Structure Functions in the Context of Few-Body Physics

abstract:
  Few-body systems offer a unique challenge to those interested in deep
inelastic scattering. Using the deuteron as the simplest and most easily
solvable nuclear system we review the main physics issues in the valence and
sea quark regimes. For the former the key issue is the understanding of Fermi
motion and binding corrections, and our ability to extract the ratio F_2n/F_2p
as x -> 1. The most recent analysis of deuteron data for F_2n/F_2p is
consistent with perturbative QCD, but inconsistent with the assumptions common
to all standard parton distribution fits. This should be taken into account in
calculating event rates at HERA --- especially at large x and Q^2. The
extraction of g_1n also presents an opportunity to refine the description of
nuclear effects in spin-dependent structure functions. In the region of small x
one must correct for shadowing and meson exchange current effects in order to
explore the flavor structure of sea, which is, in turn, deeply related to the
chiral structure of the nucleon.


title:
On the resummation of double logarithms in the process Higgs --> two
  photons

abstract:
  The decay of the Higgs boson into two photons is discussed. Using Sudakov
technicue, we study a new type of double logarithms in the case of the light
quark loop. First, we examine the origin of such logarithms at the one loop
level. Then we perform a two-loop analysis, and finally we present an explicit
result of the resummation of double logarithms in all order in QCD. The
phenomenological applications are discussed.


title: Mass of the lightest Higgs Boson in Supersymmetric Left-Right Models

abstract:
  We consider the lightest Higgs boson in naturally R-parity conserving
supersymmetric left-right models. We obtain an upper bound on the tree level
mass of this lightest Higgs boson. This upper bound depends on the $SU(2)_L$
and $SU(2)_R$ gauge couplings, and the vacuum expectation values of bidoublet
Higgs fields, which are needed to break $SU(2)_L\times U(1)_Y$. The upper bound
does not depend on either the $SU(2)_R$ breaking scale or the supersymmetry
breaking scale. We evaluate the bound numerically by assuming that the theory
remains perturbative upto some scale $\Lambda$. We find that the bound can be
considerably larger than in MSSM. The dominant radiative corrections to the
upper bound due to top-stop and bottom-sbottom systems are of the same form as
in the minimal supersymmetric standard model.


title: A Precision Measurement of Nuclear Muon Capture on 3He

abstract:
  The muon capture rate in the reaction mu- 3He -> nu + 3H has been measured at
PSI using a modular high pressure ionization chamber. The rate corresponding to
statistical hyperfine population of the mu-3He atom is (1496.0 +- 4.0) s^-1.
This result confirms the PCAC prediction for the pseudoscalar form factors of
the 3He-3H system and the nucleon.


title:
Hyperon polarization and single spin left-right asymmetry in inclusive
  production processes at high energies

abstract:
  It is shown that the polarization of hyperons observed in high energy
collisions using unpolarized hadron beams and unpolarized nucleon or nuclear
targets is closely related to the left-right asymmetries observed in single
spin inclusive hadron production processes. The relationship is most obvious
for the production of the hyperons which have only one common valence quark
with the projectile. Examples of this kind are given. Further implications of
the existence of large polarization for hyperon which has two valence quarks in
common with the projectile and their consequences are discussed. A comparison
with the available data is made. Further tests are suggested.


title: Screening Masses in SU(N) from Wilson Renormalization Group

abstract:
  We apply a gauge invariant formulation of Wilson Renormalization Group (RG)
to the computation of the Debye and transverse gluon masses in pure gauge SU(N)
at high temperature. Following the Hard Thermal Loop effective field theory as
a guideline, we develop an approximation scheme to the exact evolution
equations. The Debye mass receives sizable corrections compared to the leading
order perturbative result, mainly due to the infrared singular behavior in the
transverse gluon sector. A non-vanishing mass for the transverse gluons is
found, which acts as an infrared regulator though not efficiently enough as to
restore the validity of perturbation theory. Indeed, discussing the role of
higher dimensional operators, we show that the gauge coupling for the
transverse modes typically flows to non-perturbative values unless extremely
high temperatures are reached. After comparing our results with recent lattice
simulations, we comment on the possibility of using this formulation of the RG
as a tool to construct an effective field theory for the non-perturbative, long
wavelength, transverse modes.


title: Sleptons at LEP2 and Tevatron in R-Parity Violating SUSY

abstract:
  In supersymmetric theories with R-parity breaking, sleptons could be produced
singly in $e^+e^-$ collisions at LEP2 and in $q\bar{q}$ annihilation at the
Tevatron through interactions in which two quark or two lepton fields are
coupled to a slepton field. At LEP they could manifest themselves in Bhabha
scattering, and in the annihilation to $\mu^+\mu^-$, \taus, and $q\bar{q}$
pairs. The formation of sneutrinos, $e^+e^-\ra \ti{\nu}$, and their signals for
a mass within the reach of this machine, is an exciting speculation which can
be investigated in the coming LEP2 runs with energies close to $\sqrt{s}=200$
GeV. At the Tevatron the sleptons can be searched for as resonances in
$p\bar{p}\to \tilde{\nu} \to \ell^+\ell^-$ and $\tilde{\ell}\to \ell\nu $ final
states. Existing LEP2 and Tevatron data can be exploited to derive bounds on
the Yukawa couplings of sleptons to quark and lepton pairs.


title: Phenomenology of SUSY-models with spontaneously broken R-parity

abstract:
  We review the consequences of spontaneously broken R-parity in present and
planned lepton-lepton colliders. In the left-right models the R-parity,
$R=(-1)^{3(B-L)+2S}$, is preserved due to the gauge symmetry, but it must be
spontaneously broken in order to the scalar spectrum to be physically
consistent. The spontaneous breaking is generated via a non-vanishing VEV of at
least one of the sneutrinos, which necessarily means non-conservation of lepton
number $L$. The R-parity violating couplings are parametrized in terms of
mixing angles, whose values depend on model parameters. Combined with the
constraints derived from low-energy measurements this yields allowed ranges for
various R-parity breaking couplings. The R-parity breaking allows for the
processes in which a single chargino or neutralino is produced, subsequently
decaying at the interaction point to non-supersymmetric particles.


title: Constraining the scales of supersymmetric left-right models

abstract:
  We'll review our study of the constraints on the scales in the supersymmetric
left-right model (SUSYLR). The conservation of color and electromagnetism in
the ground state of the theory implies a relation between right-handed gauge
boson mass and soft squark mass. Furthermore, in general for heavy $W_R$,
$\tan\alpha$ is larger than one, and the right-handed sneutrino VEV,
responsible for spontaneous R-parity breaking, is at most of the order
$M_{SUSY}/h_{\Delta_R}$, where $M_{SUSY}$ is supersymmetry breaking scale and
$h_{\Delta_R}$ is the Yukawa coupling in Majorana mass term for right-handed
neutrinos.


title: Numerical study of plasmon properties in the SU(2)-Higgs model

abstract:
  We discuss an explorative computation of real time autocorrelation functions,
in the classical approximation. The results for the `plasmon' frequencies and
damping rates appear compatible with the divergencies expected from
perturbation theory.


title:
Looking for quantum SUSY signatures in top quark decays at hadron
  colliders

abstract:
  We discuss the supersymmetric quantum effects on top quark decays within the
MSSM. It turns out that t-> H+ b is the most promising candidate for carrying
large quantum SUSY signatures. As a result, the recent (tan(beta) M_H)
exclusion plots presented by the CDF Collaboration should be thoroughly revised
in the light of the MSSM.


title: Single Sneutrino/Slepton Production at LEP2 and the NLC

abstract:
  We propose a new method of detecting supersymmetry at LEP2 when R-parity is
violated by an LLE operator. We consider the processes $e\gamma\ra\snu_j e_k$
and $e\gamma \ra \slep_k \bar{\nu}_j$. These are sensitive to seven of the nine
LLE-operators. A Monte-Carlo analysis is performed to investigate the
sensitivity to the sneutrino signal, and the 5$\sigma$ discovery contours in
the mass vs. coupling plane are presented. For an integrated luminosity of 100
pb^-1, sneutrinos with masses up to 170 GeV/c^2 could be discovered in the near
future at LEP2. For the charged slepton production the cross-section is too low
to be detectable.


title: The photon spectrum in quarkonia decays

abstract:
  I discuss recent theoretical results for inclusive decays of quarkonia into a
photon plus hadrons, and summarize the status of perturbative calculations.


title:
Possible manifestation of heavy stable colored particles in cosmology
  and cosmic rays

abstract:
  We discuss the cosmological implications as well as possible observability of
massive, stable, colored particles which often appear in the discussion of
physics beyond the standard model. We argue that if their masses are more than
a few hundred GeV and if they saturate the halo density and/or occur with
closure density of the universe, they are ruled out by the present WIMP search
experiments as well as the searches for anomalous heavy isotopes of ordinary
nuclei. We then comment on the possibility that these particles as well as the
monopoles could be responsible for the ultra high energy cosmic rays with
energy $\geq 10^{20}$ eV and point out that their low inelasticity argues
against this.


title: Gell-Mann-Okubo Mass Formula Revisited

abstract:
  We show that the application of Regge phenomenology to SU(4) meson multiplets
leads to a new Gell-Mann-Okubo mass-mixing formula in the SU(3) sector, 3m_1^2
+ (cos theta)^2 m_0^2 + (sin theta)^2 m_{0'}^2 + sqrt{2} sin(2theta) (m_0^2 -
m_{0'}^2) = 4m_{1/2}^2, where m_1,m_{1/2},m_0,m_{0'} are the masses of the
isovector, isodoublet, isoscalar mostly octet and isoscalar mostly singlet
states, respectively, and theta is the nonet mixing angle. For an ideally mixed
nonet, theta = arctan(1/sqrt{2}), this formula reduces to 2m_0^2 + 3m_1^2 =
4m_{1/2}^2 + m_{0'}^2 which holds with an accuracy of ~1% for vector and tensor
mesons. For pseudoscalar mesons, with the eta-eta' mixing angle
-arctan[1/(2sqrt{2})] ~ -19.5^o, in agreement with experiment, it leads to the
relation 4m_K^2 = 3m_pi^2 + m_{eta'}^2 which holds to an accuracy of better
than 1% for the measured pseudoscalar meson masses.


title: Electromagnetic Mass Difference of Heavy Mesons

abstract:
  Using the Cottingham formula, we give an estimate of the electromagnetic mass
splitting of pseudoscalar heavy mesons in the beauty and charm sector. We
include in the dispersion relation the Born term, the $1^-$ resonance and the
positive parity $1^+$ resonance. We also evaluate the contribution to the mass
difference from the isospin breaking quark mass differences. Our results:
$m_{B^+}-m_{B^0} = - 0.83\pm 0.34 MeV$ and $m_{D^+}-m_{D^0} = + 4.33\pm 0.37
MeV$, are in agreement with the experimental measurements: $m_{B^+}-m_{B^0} = -
0.35\pm 0.29 MeV$ and $m_{D^+}-m_{D^0} = + 4.78\pm 0.10 MeV$. We also compute
the mass differences in the infinite heavy quark mass limit, which show small
deviations from the finite mass results for the B case and 30% effects in the
charm case.


title:
Domain Wall Problem of Axion and Isocurvature Fluctuations in Chaotic
  Inflation Models

abstract:
  We study the domain wall problem of an axion in chaotic inflation models. We
show that the production of domain walls does not occurs if the Peccei-Quinn
scalar has a flat potential and its breaking $F_{a}$ is larger than $\sim
10^{15}$GeV. We find that too large isocurvature fluctuations are produced for
such high $F_{a}$. In order for those isocurvature fluctuations to be
consistent with observations of the large scale structure of the universe, the
self-coupling constant $g$ and the breaking scale of the Peccei-Quinn scalar
should be $g \simeq (1-2.8)\times 10^{-13}$ and $F_{a} \simeq (0.6-1.5)\times
10^{15}$GeV, respectively. In particular the value of self-coupling constant is
almost the same as that required for a chaotic inflation, which strongly
suggests that the Peccei-Quinn scalar itself is an inflaton.


title: A perturbative approach to the eta_c-gamma transition form factor

abstract:
  The eta_c-gamma transition form factor is calculated within a perturbative
approach. For the eta_c-meson, a wave function of the Bauer-Stech-Wirbel type
is used where the two free parameters, namely the decay constant f(eta_c) and
the transverse size of the wave function, are related to the Fock state
probability and the width for the two-photon decay Gamma[eta_c -> gamma gamma].
The Q^2 dependence of the eta_c-gamma transition form factor is well
determined.


title: Bileptons - Present Constraints and Future Prospects at Colliders

abstract:
  Bosons which couple to two leptons and carry lepton number L=2, generically
called bileptons, appear in many extensions of the standard model. We review
the present constraints on bilepton parameters coming from low and high energy
data. In particular, we point out that the amplitude of $\mu-e$ conversion in
nuclei is enhanced by large logarithms if compared with the $\mu\to e\gamma$
one. Bilepton couplings will be tested most stringently at future colliders.
For wide range of neutrino masses the cross section of one of the processes
$e^-e^- (\mu^-\mu^-)\to \ell_i^-\ell_i^-,$ $i=e,\mu, \tau,$ mediated by scalar
triplet bilepton, has such a lower bound that it should be observed at future
facilities.


title: On the Bose-Einstein Effect and the W Mass

abstract:
  We present an implementation of the Bose - Einstein effect in a Monte Carlo
generator for $W^-W^+ $ production in the $e^-e^+$ annihilation by means of the
weight method. We check that the shift of the W mass in four jet events due to
this effect is similarly small as for the other prescription used recently by
Jadach and Zalewski. Possible generalization of this result is shortly
discussed.


title: QCD Instantons at HERA

abstract:
  Phenomenological aspects of chirality violating processes induced by QCD
instantons in deep inelastic scattering are discussed. First instanton searches
and the prospects for their experimental discovery at HERA are presented.


title: Semi-analytic predictions for W pair production at 500 GeV

abstract:
  We give a short review on the semi-analytic approach to off-shell W pair
production at 500 GeV and above. Numerical calculations are performed with the
Fortran program GENTLE v. 2.0 and its upgrade. Recent extensions include: (i)
angular distribution for the CC11 process with LLA QED corrections; (ii)
anomalous couplings. As an application we study the sensitivity of total
cross-section and forward-backward asymmetry to anomalous couplings. A
noticeable sensitivity from the asymmetry appears only for a parity-violating
anomalous coupling.


title: The Z Boson Resonance Parameters

abstract:
  The Z line shape is measured at LEP/CERN with an accuracy at the per mille
level. Usually it is described in the Standard Model of electroweak
interactions with account of quantum corrections. Alternatively, one may
attempt an S-matrix based model-independent approach in order to extract
quantities like mass and width of the Z boson. I describe the formalism and its
application to data.


title: oneloop 2.0 -- A Program Package calculating One-Loop Integrals

abstract:
  We present an improved version of our program package oneloop which --
written as a package for MAPLE -- solves one-loop Feynman integrals. The
package is calculating one-, two- and three-point functions both algebraically
and numerically to any tensor rank. In addition to the original version oneloop
2.0 also calculates infrared divergent integrals. Higher powers of propagator
terms and the $O(\eps)$ parts relevant for two-loop calculations are now
supported.


title: Modification of the $\phi$-meson spectrum in nuclear matter

abstract:
  The vacuum spectrum of the $\phi$-meson is characterized by its decay into
$K{\bar K} $. Modifications of the $K {\bar K}$-loops in baryonic matter change
this spectrum. We calculate these in-medium modifications taking both s- and
p-wave kaon-nucleon interactions into account. We use results of the in-medium
$K$ and $\bar K$ spectra determined previously from a coupled channel approach
based on a chiral effective Lagrangian. Altogether we find a very small shift
of the $\phi$ meson mass, by less than 10 MeV at normal nuclear matter density
$\rho_0$. The in-medium decay width of the $\phi$ meson increases such that its
life time at $\rho=\rho_0$ is reduced to less than 5 fm/c. It should therefore
be possible to observe medium effects in reactions such as $\pi^- p \to \phi n$
in heavy nuclei, where the $\phi$ meson can be produced with small momentum.


title: Nonperturbative Higgs propagator: NLO correction in the 1/N expansion

abstract:
  We derive a nonperturbative result for the Higgs propagator by calculating
the NLO correction in the 1/N expansion of O(N) sigma models. For dealing with
the 1/N expansion beyond leading order, we develop techniques to calculate
certain infinite sets of multiloop Feynman diagrams. We then calculate the
Higgs lineshape in fermion scattering, as seen for instance at a muon collider.
We compare with the existing two-loop perturbative results. There is a
considerable discrepancy between perturbation theory and the 1/N expansion in
LO. By including the NLO correction, this discrepancy is reduced dramatically.
The results are in very good agreement with the two-loop result even for masses
as high as 850 GeV. A maximum of the mass is reached at 930 GeV. For
phenomenological purposes, we give a simple approximate relation between the
Higgs mass and width.


title: Perspectives in High Energy Physics

abstract:
  A broad survey of High Energy Physics (HEP) both within as well as beyond the
Standard Model is presented emphasizing the unsolved problems. Inspite of the
spectacular success of the Standard Model, there is a serious crisis facing the
field. The importance of research on new methods of acceleration that can
resolve this crisis by taking us to superhigh energies is stressed. We briefly
review the status of HEP in India and offer suggestions for the future.


title:
Testing Target Independence of the `Proton Spin' Effect in
  Semi-Inclusive Deep Inelastic Scattering

abstract:
  A natural consequence of the composite operator propagator-vertex description
of deep inelastic scattering developed by the authors is that the anomalous
suppression observed in the flavour singlet contribution to the first moment of
the polarised proton structure function $g_1^p$ (the `proton spin' problem) is
not a special property of the proton structure but is a target independent
effect which can be related to an anomalous suppression in the QCD topological
susceptibility. In this paper, it is shown how this target independent
mechanism can be tested in semi-inclusive deep inelastic scattering in which a
pion or D meson carrying a large target energy fraction $z$ is detected in the
target fragmentation region.


title: The theory of the Landau, Pomeranchuk, Migdal effect

abstract:
  Bremsstrahlung of photons from highly relativistic electrons is investigated.
The cross section of the processes, which is suppressed due to a multiple
scattering of an emitting electron in dense media (LPM effect) and due to
photon interaction with electrons of a medium, is calculated with an accuracy
up to "next to leading logarithm" and with the Coulomb corrections taken into
account. Making allowances for a multiple scattering and a polarization of a
medium an analysis of radiation on a target boundary is carried out. The method
of consideration of radiation in a thin target under influence of the LPM
effect is developed. Interrelation with the recent experiment is discussed.


title:
Direct extraction of the chiral quark condensate and bounds on the light
  quark masses

abstract:
  We select sum rules from which one can extract directly reliable limits on
the size of the chiral symmetry breaking light quark condensate
$<\bar\psi\psi>$. Combined results from the nucleon and $B^*-B$ mass-splitting
sum rules give a result compatible with the standard value: $<\bar\psi\psi> (1
GeV) \simeq (-229 MeV)^3$, through the determinations of the quark-gluon mixed
condensate. The vector form factor of the $D\rar K^*l\nu$ semi-leptonic decay
leads to the range $0.6\leq <\bar\psi\psi> (-229 MeV)^3 \leq 1.5$. The upper
limit combined with the Gell-Mann-Oakes-Renner (GMOR) relation implies the
interesting lower bound on the sum of light quark masses:$(m_u+m_d) (1 GeV)
\geq$ 9.4 MeV, which combined with the ratio of light quark masses from chiral
perturbation theory leads to $m_s (1 GeV) \geq (121\pm 12)$ MeV. The lower
limit combined with the positivity of the $m_q^2$ contribution to the GMOR
relation leads to the upper bound : $(m_u+m_d) (1 GeV) \leq$ 15.7 MeV, which is
independent on the nature of chiral symmetry breaking.


title: Experimental aspects of colour reconnection

abstract:
  This report summarises experimental aspects of the phenomena of colour
reconnection in W+W- production, concentrating on charged multiplicity and
event shapes, which were carried out as part of the Phenomenology Workshop on
LEP2 Physics, Oxford, Physics Department and Keble College, 14-18 April, 1997.
The work includes new estimates of the systematic uncertainty which may be
attributed to colour reconnection effects in experimental measurements of Mw.


title:
Effect of contact ineractions on higgs production cross-section at an
  $e^+e^-\to HZ$ collider

abstract:
  New interactions appearing at a scale $\Lambda$ larger than the weak
interaction scale v can affect physical processes at energies below $\Lambda$
through non-renormalizable $SU(3)\times SU(2)\times U(1)_y$ invariant operators
added to the standard model Lagrangian. In this article we investigate the
effect of flavor conserving contact interactions on the total cross-section for
the process $e^+e^-\to HZ$ at $\sqs =500$ Gev. We find that for $\Lambda\approx
2.5 $ Tev, which is consistent with LEP and SLD asymmetry measurements on Z
peak as well as theoretical estimates, these operators can increase the total
cross-section by a factor of 3 relative to the SM for intermediate mass higgs
boson.


title: Radiative Transition of Massless Neutrino in Strong Magnetic Field

abstract:
  Radiative transition of massless neutrino $\nu_l \to \nu_l + \gamma$ ($l = e,
\mu, \tau$) in a strong magnetic field is investigated in the framework of the
Standard Model. The process probability and the mean values of the neutrino
energy and momentum loss are presented. Possible astrophysical manifestation of
the process considered is analysed.


title: Electroweak dipole moment form factors of the top quark in supersymmetry

abstract:
  We present a complete analysis of the electrtic and weak dipole moment form
factors of the top quark within the Minimal Supersymmetric Standard Model with
complex parameters. We include gluino, chargino, and neutralino exchange in the
loops of the $\gamma t\bar{t}$ and $Z t\bar{t}$ vertices.


title: Radiative Corrections to the Stefan-Boltzmann Law

abstract:
  Photons in blackbody radiation have non-zero interactions due to their
couplings to virtual electron-positron pairs in the vacuum. For temperatures
much less than the electron mass $m$ these effects can be described by an
effective theory incorporating the Uehling and Euler-Heisenberg interactions as
dominant terms. By a redefinition of the electromagnetic field, the Uehling
term is shown not to contribute. The Stefan-Boltzmann energy is then modified
by a term proportional with $T^8/m^4$ in agreement with the semi-classical
result of Barton. The same effects give a speed of light smaller than one at
non-zero temperatures as has also recently been derived using full QED.


title:
Semileptonic decay constants of octet baryons in the chiral
  quark-soliton model

abstract:
  Based on the recent study of the magnetic moments and axial constants within
the framework of the chiral quark-soliton model, we investigate the baryon
semileptonic decay constants $(f_1,f_2)$ and $(g_1, g_2)$. Employing the
relations between the diagonal transition matrix elements and off-diagonal ones
in the vector and axial-vector channels, we obtain the ratios of baryon
semileptonic decay constants $f_2/f_1$ and $g_1/f_1$. The $F/D$ ratio is also
discussed and found that the value predicted by the present model naturally
lies between that of the Skyrme model and that of the nonrelativistic quark
model. The singlet axial constant $g^{(0)}_A$ can be expressed in terms of the
$F/D$ ratio and $g^{(3)}_A$ in the present model and turns out to be small. The
results are compared with available experimental data and found to be in good
agreement with them. In addition, the induced pseudotensor coupling constants
$g_2/f_1$ are calculated, the SU(3) symmetry breaking being considered. The
results indicate that the effect of SU(3) symmetry breaking might play an
important role for some decay modes in hyperon semileptonic decay.


title: Few-body aspects of non-perturbative QCD

abstract:
  After some general remarks on non-perturbative QCD I present shortly models
which lead to a color-electric flux tube formation. The implications of such a
flux tube formation especially on high energy scattering are discussed.


title: B Decays to Charmless VP Final States

abstract:
  The CLEO Collaboration has now observed the decays $B^+ \to \omega \pi^+$ and
$B \to \omega K^+$ with branching ratios of $(1.1^{+0.6}_{-0.5} \pm 0.2) \times
10^{-5}$ and $(1.5^{+0.7}_{-0.6} \pm 0.3) \times 10^{-5}$, respectively. These
are the first reported decays to charmless final states involving a vector (V)
and a pseudoscalar (P) meson. The implications of these decays for others of B
mesons to charmless VP final states are explored. In a model-independent
approach, using only flavor SU(3) symmetry, several tests are proposed for an
anticipated hierarchy among different contributions to decay amplitudes.


title:
The $\rho $ Meson and the Thermal Behavior of an Effective Hadronic
  Coupling Constant

abstract:
  Vector Meson Dominance ideas together with a Finite Energy QCD sum rule
allows for the determination of the $q^{2}$- and the $T$- dependence of the
effective hadronic coupling constant $g_{\rho \pi \pi}$ in the space-like
region. It turns out that $g_{\rho \pi \pi}(q^{2},T)$ vanishes at the critical
temperature $T_{c}$, independently of $q^{2}$. A comparison with a previous
independent QCD determination of the electromagnetic pion form factor at finite
temperature supports the validity of Vector Meson Dominance at finite
temperature. We find also thet the pion radius increases with $T$, having a
divergent behavior at $T_{c}$.


title:
Electric dipole moment of top quark and CP-violating asymmetries in
  gamma gamma -> t tbar

abstract:
  CP-violating asymmetries due to a possible electric dipole interaction of the
top quark in the production and subsequent decay of top quark-top antiquark
pair in photon-photon collisions are studied. The asymmetries defined can be
used to determine the imaginary part of the electric dipole form factors. A
gamma-gamma collider with photon beams generated from laser back-scattering off
electron beams with an integrated geometric luminosity of 20 fb^{-1} can put a
limit of the order of 10^{-17} e cm on the imaginary part of the electric
dipole form factor of the top quark if the electron beams have longitudinal
polarization and the laser beams have circular polarization.


title: Where are the BFKL Pomeron and shadowing corrections in DIS?

abstract:
  In this talk, I will argue that the HERA experimental data show that the
typical parameter ($\kappa$) responsible for the value of the shadowing
corrections (SC) in DIS is so large that the BFKL Pomeron is hidden under SC.
The SC turn out to be large enough but mostly for the gluon structure function
which is not well determined by the available experimental data and by the
current theoretical procedure.


title: Higgs Pain? Take a Preon!

abstract:
  The Higgs mechanism is the favourite cure for the main problem with
electroweak unification, namely how to reconcile a gauge theory with the need
for massive gauge bosons. This problem does not exist in preon models for quark
and lepton substructure with composite $Z^0$ and $W$s, which, consequently,
also avoid all other theoretical complications and paradoxes with the Higgs
mechanism. We present a new, minimal preon model, which explains the family
structure, and predicts several new, heavy quarks, leptons and vector bosons.
Our preons obey a phenomenological supersymmetry, but without so-called squarks
and sleptons, since this SUSY is effective only on the composite scale.


title: Charm -- a thermometer of the mixed phase

abstract:
  A charmed quark experiences drag and diffusion in the quark-gluon plasma, as
well as strong interaction with the plasma surface. Our simulations indicate
that charmed quarks created in heavy ion collisions will be trapped in the
mixed phase and will come to equilibrium in it. Their momentum distribution
will thus reflect the temperature at the confinement phase transition.


title: Electroweak Working Group Report

abstract:
  The report summarizes the results of the activities of the Working Group on
Precision Calculations for the Z Resonance at CERN during 1994.


title: Comment on "Hara's theorem in the constituent quark model"

abstract:
  It is pointed out that current conservation alone does not suffice to prove
Hara's theorem as it was claimed recently. By explicit calculation we show that
the additional implicit assumption made in such "proofs" is that of a
sufficiently localized current.


title: Implications of a J^PC exotic

abstract:
  Recent experimental data from BNL on the isovector J^PC =1^-+ exotic at 1.6
GeV in \rho\pi indicate the existence of a non-quarkonium state consistent with
lattice gauge theory predictions. We discuss how further experiments can
strengthen this conclusion. We show that the \rho\pi, \eta'\pi and \eta\pi
couplings of this state qualitatively support the hypothesis that it is a
hybrid meson, although other interpretations cannot be eliminated.


title: Non-Perturbative Quantum Dynamics of a New Inflation Model

abstract:
  We consider an O(N) model coupled self-consistently to gravity in the
semiclassical approximation, where the field is subject to `new inflation' type
initial conditions. We study the dynamics self-consistently and
non-perturbatively with non-equilibrium field theory methods in the large N
limit. We find that spinodal instabilities drive the growth of
non-perturbatively large quantum fluctuations which shut off the inflationary
growth of the scale factor. We find that a very specific combination of these
large fluctuations plus the inflaton zero mode assemble into a new effective
field. This new field behaves classically and it is the object which actually
rolls down. We show how this reinterpretation saves the standard picture of how
metric perturbations are generated during inflation and that the spinodal
growth of fluctuations dominates the time dependence of the Bardeen variable
for superhorizon modes during inflation. We compute the amplitude and index for
the spectrum of scalar density and tensor perturbations and argue that in all
models of this type the spinodal instabilities are responsible for a `red'
spectrum of primordial scalar density perturbations. A criterion for the
validity of these models is provided and contact with the reconstruction
program is established validating some of the results within a non-perturbative
framework. The decoherence aspects and the quantum to classical transition
through inflation are studied in detail by following the full evolution of the
density matrix and relating the classicality of cosmological perturbations to
that of long-wavelength matter fluctuations.


title: Deep-Inelastic Diffraction and the Pomeron as a Single Gluon

abstract:
  Deep-inelastic diffractive scaling provides fundamental insight into the QCD
pomeron. It is argued that single gluon domination of the structure function,
together with the well-known Regge pole property, determines that the pomeron
carries color-charge parity $ C_c = -1~$ and, at short distances, is in a
super-critical phase of Reggeon Field Theory. The main purpose of the talk is
to describe the relationship of the super-critical pomeron to QCD.


title:
The Supersymmetric Particle Spectrum in Orbifold Compactifications of
  String Theory

abstract:
  The supersymmetry breaking parameters and the resulting supersymmetric
particle spectrum are studied in orbifold compactifications of string theory
under the assumption that unification of gauge coupling constants at about
$10^{16}$ GeV is a consequence of large moduli dependent string loop threshold
corrections. The effect on the spectrum of various assumptions as to the
modular weights of the states, the values of the Green-Schwarz parameter,
$\delta_{GS}$, the origin of the $\mu$ parameter and the moduli dependence of
Yukawa couplings is discussed. The effect of radiative corrections to the
effective potential is also considered.


title: Leptoquarks: Pride and Prejudice

abstract:
  Attempts to understand the recent observation of an excess of events in the
neutral and charged current channels at high$-Q^2$ at HERA has provided an
excellent example of how experiments at both low and high energies can be used
to simultaneously constrain scenarios which predict new physics beyond the
Standard Model. In this talk I will discuss this subject from the point of view
of the construction of new models of leptoquarks.


title: A modified BFKL equation with unitarity

abstract:
  We propose a modified Balitskii-Fadin-Kuraev-Lipatov equation from the
viewpoint of the resummation technique, which satisfies the unitarity bound.
The idea is to relax the strong rapidity ordering and to restrict phase space
for real gluon emissions in the evaluation of the BFKL kernel. It is found that
the gluon distribution function rises as a power of the Bjorken variable $x$,
and then saturates at $x\to 0$. We estimate that the saturation begins to occur
for $x< 10^{-4}$.


title: Heavy Particle Effective Field Theories

abstract:
  Starting from a theory of heavy particles and antiparticles, the path
integral formulation of an effective field theory which describes the low
momentum interactions is presented. The heavy degrees of freedom are identified
and explicitly integrated out from the functional integral of the full theory.
Using this method, the effective Lagrangian, which may be calculated to
arbitrary subleading order in an inverse mass expansion, is derived for fields
of spin-0, 1/2, and 1.


title: Reparameterization Invariance in Heavy Particle Effective Field Theories

abstract:
  In a low energy effective theory, the fields of heavy particles with mass $m$
and total momentum $p$ depend on both a velocity $v$ and a residual momentum
$k$ such that $p =mv +k$. However, there is some arbitrariness in such a
description because one may also use a slightly different velocity with a
compensating change in the residual momentum. This non-uniqueness is the origin
of an invariance under such a reparameterization which imposes non-trivial
constraints on the theory. The implications of this invariance for effective
theories of heavy spin-0, 1/2, and 1 fields is investigated.


title: Yukawa Interaction from a SUSY Composite Model

abstract:
  We present a composite model that is based on non-perturbative effects of N=1
supersymmetric SU(N_C) gauge theory with N_f=N_C+1 flavors. In this model, we
consider N_C=7, where all matter fields in the supersymmetric standard model,
that is, quarks, leptons and Higgs particles are bound states of preons and
anti-preons. When SU(7)_H hyper-color coupling becomes strong, Yukawa couplings
of quarks and leptons are generated dynamically. We show one generation model
at first, and next we show models of three generations.


title: Jet Production in Deep-inelastic Scattering at HERA

abstract:
  The main experimental results on jet production at HERA are reviewed. A study
of jet shapes shows that the internal structure of jets is well understood. The
potential to accurately determine the strong coupling constant using jet rates
is discussed. First attempts to extract the gluon density in next-to-leading
order are presented. Although fixed order perturbative QCD is able to describe
the shape of most variables associated to the hard subprocess leading to jets,
it does not reproduce the absolute dijet rate over a large phase space region.


title: Collective Dynamics of a Domain Wall - an Outline

abstract:
  We briefly outline the approach to extracting collective dynamics of a domain
wall from field equations which has been proposed by us in
Nucl.Phys.B450(1995)174-188 and further developed in hep-th/9703168.


title: CP Violation in Low-Energy SUSY

abstract:
  We discuss CP violation in the context of the minimal SUSY extension of the
standard model as well as in a generic low-energy SUSY model. After analyzing
the SUSY contributions to the observed CP violation in the kaon system, we
emphasize the prospects for disentangling SUSY loop contributions from pure SM
effects in B physics.


title:
Radiative Corrections to the Decay $B\to \pi e\nu$ and the Heavy Quark
  Limit

abstract:
  We calculate radiative corrections to the light-cone sum rule for the
semileptonic form factor in $B\to\pi e\nu$ decays and thus remove the major
uncertainty in determining the CKM mixing angle $|V_{ub}|$ by this method. We
discuss the remaining uncertainties and perspectives for further studies. The
structure of the radiative corrections suggests factorization of soft
(end-point) and hard rescattering contributions in heavy-to-light decays in the
heavy quark limit.


title: SUSY in Rare and CP-Violating B Decays

abstract:
  In this talk we discuss rare B decays (b -> s gamma, b -> s g, b -> s l^+
l^-), B-\bar{B} oscillations and CP violation in B physics in the context of
low-energy SUSY. We outline the variety of predictions that arise according to
the choice of the SUSY extension ranging from what we call the "minimal"
version of the MSSM to models without flavour universality or with broken
R-parity. In particular, we provide a model-independent parameterization of the
SUSY FCNC and CP-violating effects which is useful in tackling the problem in
generic low-energy SUSY. We show how rare B decays and CP violation in B-decay
amplitudes may be complementary to direct SUSY searches at colliders, in
particular for what concerns extensions of the most restrictive version of the
MSSM.


title: Leptophobic Character of the Z' in an SU(3)_C x SU(3)_L x U(1)_X model

abstract:
  We show that the extra Z boson predicted within the so-called "3-3-1" model
has a leptophobic character, and analyse its effects on Z decay widths and on
the t\bar t production cross section in p\bar p collisions at the Fermilab
Tevatron. Recent model-independent analysis are applied in order to estimate
the contribution of this Z' to the observables that will be measured at LEP2.


title: Hadron multiplicity as the limit of jet multiplicity at high resolution

abstract:
  Recently exact numerical results from the evolution equation for parton
multiplicities in QCD jets have been obtained. A comparison with various
approximate results is presented. A good description is obtained not only of
the jet multiplicities measured at LEP-1 but also of the hadron multiplicities
for $cms$ energies above 1.6 GeV in \epem annihilation. The solution suggests
that a final state hadron can be represented by a jet in the limit of small
(nonperturbative) $k_\perp$ cut-off $Q_0$. In this description using as
adjustable parameters only the QCD scale $\Lambda$ and the cut-off $Q_0$, the
coupling $\alpha_s$ can be seen to rise towards large values above unity at low
energies.