title:
Estimates of higher-dimensional vacuum condensates from the instanton
  vacuum

abstract:
  We calculate the values of non-factorizable dimension-7 vacuum condensates in
the instanton vacuum. We comment on a method, recently proposed by Oganesian,
to estimate the dimension-7 condensates by factorization of dimension-10
condensates in various inequivalent ways. The instanton estimates could be used
to analyze the stability of QCD sum rules with increasing dimensions.


title: Compositeness and the asymmetries of leptons at the Z^0 peak

abstract:
  We study the effects on the leptonic asymmetries A_{FB}, A_{pol} and A_{LR}
coming from a model of compositeness. We consider the effects coming from the
self-energies and the vertex correction to $Z l^+ l^-$. Thus we use the
Altarelli parametrization of the oblique corrections. We get the asymptotic
limits of these corrections in terms of the parameters $(m^*, \Lambda, f, f')$
and we get bounds for the quotient $m^*/\Lambda$ with different values of $(f,
f')$. We conclude that both asymmetries produce bounds for such quotient when
$f'$ overweigth to $f$, and this fact is related with the breakdown of the
custodial symmetry.


title: Search for the scalar a_0 and f_0 mesons in the \phi radiative decays

abstract:
  The potentialities of the production of the $a_0$ and $f_0$ mesons in the
$\phi$ radiative decays are considered based on a new two-channel analysis of
the $\pi\pi$ scattering in a energy region near 1 GeV. We predict
$BR(\phi\to\gamma f_0(980))\sim10^{-5}-10^{-4}$ that is a great value for the
decay forbidden by the Okubo-Zweig-Iizuka rule. We discuss the four-quark,
$K\bar K$-molecule and two-quark scenarios for the $a_0$ and $f_0$ mesons. It
is presented arguments that the $e^+e^-$-colliders and especially the $\phi$
factories give the possibility to choose a single one out of them.


title:
Mechanisms of the Reaction $\pi^-p\to a^0_0(980)n\to\pi^0\eta n$ at High
  Energies

abstract:
  Over the last twenty years, it was assumed that the reaction $\pi^-p\to
a^0_0(980)n\to\pi^0\eta n$ at high energies is dominated by $b_1$ Regge pole
exchange. We show that the new Brookhaven and Serpukhov data on the $t$
distributions for this reaction can be explained within the framework of the
Regge pole model only if the $\rho_2$ Regge pole exchange conspiring with its
daughter plays a crucial role. The tentative estimates of the absolute
$\pi^-p\to a^0_0(980)n\to\pi^0\eta n$ reaction cross section are obtained. The
contributions of the one-pion exchange mechanism and the Regge cuts are also
estimated.


title: High Temperature Dimensional Reduction and Parity Violation

abstract:
  The effective super-renormalizable 3-dimensional Lagrangian, describing the
high temperature limit of chiral gauge theories, has more symmetry than the
original 4d Lagrangian: parity violation is absent. Parity violation appears in
the 3d theory only through higher-dimensional operators. We compute the
coefficients of dominant P-odd operators in the Standard Electroweak theory and
discuss their implications. We also clarify the parametric accuracy obtained
with dimensional reduction.


title: Scaling violation and shadowing corrections at HERA

abstract:
  We study the value of shadowing corrections (SC) in HERA kinematic region in
Glauber - Mueller approach. Since the Glauber - Mueller approach was proven in
perturbative QCD in the double logarithmic approximation (DLA), we develop the
DLA approach for deep inelastic structure function which takes into account the
SC. Our estimates show small SC for $F_2$ in HERA kinematic region while they
turn out to be sizable for the gluon structure function. We compare our
estimates with those for gluon distribution in leading order (LO) and next to
leading order (NLO) in the DGLAP evolution equations.


title: Instantons, Spin Crisis and High $Q^2$ Anomaly at HERA

abstract:
  The contribution of the nonperturbative quark-gluon interaction induced by
the instantons to $g_1^p(x,Q^2)$ and $F_2^p(x,Q^2)$ structure functions is
estimated. It is shown that nontrivial $Q^2$ dependence of the instanton
contribution to $g_1^p(x,Q^2)$ allows us to explain the observed decreasing of
the part of the proton spin carried by quarks without involving a large
positive gluon polarization. It is demonstrated that the anomalous enhancement
of the instanton contribution to $F_2^p(x,Q^2)$ structure function, due to
multiple emission of the gluons from instanton vertex, can be one of the
reasons for the excess of the DIS events at HERA at high $Q^2 $ and $x$.


title:
A Complete Leading-Order, Renormalization-Scheme-Consistent Calculation
  of Structure Functions

abstract:
  We present consistently ordered calculations of the structure functions
F_2(x,Q^2) and F_L(x,Q^2), in different expansion schemes. After discussing the
standard expansion in powers of alpha_s(Q^2) we consider a leading-order
expansion in ln(1/x) and finally an expansion which is leading order in both
ln(1/x) and alpha_s(Q^2), and which is the only really correct expansion
scheme. Ordering the calculation in a renormalization-scheme-consistent manner,
there is no factorization scheme dependence, and the calculational method
naturally includes to the ``physical anomalous dimensions'' of Catani. However,
it imposes stronger constraints than just the use of these effective anomalous
dimensions. A relationship between the small-x forms of the inputs F_2(x,Q_I^2)
and F_L(x,Q_I^2) is predicted. Analysis of a wide range of data for F_2(x,Q^2)
is performed, and a very good global fit obtained, particularly for data at
small x. The fit allows a prediction for F_L(x,Q^2) to be produced, which is
smaller than those produced by the usual NLO-in-alpha_s(Q^2) fits to F_2(x,Q^2)
and different in shape.


title: Theoretical aspects of W physics

abstract:
  High-precision predictions for W-production processes are complicated by the
instability of the W bosons, requirements of gauge invariance, and the
necessity to include radiative corrections. Salient features and recent
progress concerning these issues are discussed for the process ee->WW->4f.


title: Effective theory for real-time dynamics in hot gauge theories

abstract:
  For a high temperature non-Abelian plasma, we reformulate the hard thermal
loop approximation as an effective classical thermal field theory for the soft
modes. The effective theory is written in local Hamiltonian form, and the
thermal partition function is explicitly constructed. It involves an
ultraviolet cutoff which separates between hard and soft degrees of freedom in
a gauge-invariant way, together with counterterms which cancel the cutoff
dependence in the soft correlation functions. The effective theory is well
suited for numerical studies of the non-perturbative dynamics in real time, in
particular, for the computation of the baryon number violation rate at high
temperature.


title:
Instanton-induced charm contribution to polarized deep-inelastic
  scattering

abstract:
  Recent data on B decays involving $\eta'$ may be explained if the singlet
axial current of charmed quarks has large matrix element to $\eta'$, and
instantons were shown to be able to generate this effect. We study the
magnitude of charm contributions to nucleon polarized structure functions
generated in a similar way. Comparing the charm contribution, which is related
to a dim(6) gluonic operator, to that of light quarks, which are related by the
anomaly equation to $G\tilde G$, we found that $\Delta c/\Delta\Sigma$ =
-(0.2-0.08). Future experiments like COMPASS at CERN identifying charm
production in DIS can measure this ``intrinsic polarized charm'' component of
the nucleon.


title: R--Parity Violating Signals for Chargino Production at LEP II

abstract:
  We study chargino pair production at LEP II in supersymmetric models with
spontaneously broken R-parity. We perform signal and background analyses,
showing that a large region of the parameter space of these models can be
probed through chargino searches at LEP II. In particular, we determine the
attainable limits on the chargino mass as a function of the magnitude of the
effective bilinear R-parity violation parameter $\epsilon$, demonstrating that
LEP II is able to unravel the existence of charginos with masses almost up to
its kinematical limit even in the case of R-parity violation. This requires the
study of several final state topologies since the usual MSSM chargino signature
is recovered as $\epsilon \to 0$. Moreover, for sufficiently large $\epsilon$
values, for which the chargino decay mode $\chi^\pm \to \tau^\pm J$ dominates,
we find through a dedicated Monte Carlo analysis that the $\chi^\pm$ mass
bounds are again very close to the kinematic limit. Our results establish the
robustness of the chargino mass limit, in the sense that it is basically
model-independent. They also show that LEP II can establish the existence of
spontaneous R-parity violation in a large region of parameter space should
charginos be produced.


title: Everything about reggeons.Part I:Reggeons in "soft" interaction

abstract:
  This is the first part of my lectures on the Pomeron structure which I am
going to read during this academic year at the Tel Aviv university. The main
goal of these lectures is to remind young theorists as well as young
experimentalists of what are the Reggeons that have re-appeared in the high
energy phenomenology to describe the HERA and the Tevatron data. Here, I show
how and why the Reggeons appeared in the theory, what theoretical problems they
have solved and what they have failed to solve. I describe in details what we
know about Reggeons and what we do not. The major part of these lectures is
devoted to the Pomeron structure, to the answer to the questions: what is the
so called Pomeron; why it is so different from other Reggeons and why we have
to introduce it. In short, I hope that this lectures will be the shortest way
to learn everything about Reggeons from the beginning to the current
understanding. I concentrate on the problem of Reggeons in this lectures while
the Reggeon interactions or the shadowing corrections I plan to discuss in the
second part of my lectures. I include here only a short lecture with an outline
of the main properties of the shadowing corrections to discuss a correct (from
the point of the Reggeon approach) strategy of the experimental investigation
of the Pomeron structure.


title: Twist-4 effects and $Q^{2}$ dependence of diffractive DIS

abstract:
  In this letter we report the direct perturbative QCD evaluation of twist-4
effects in diffractive DIS. They are large and have a strong impact on the
$Q^2$ dependence of diffractive structure functions at large $\beta$. Based on
the AGK rules, we comment on the possible contribution from diffractive higher
twists to $\propto {1 \over Q^{2}}$ corrections to proton structure function at
small $x$. These corrections to the longitudinal structure function $F_{L}$ may
be particularly large.


title: Chiral Perturbation Theory and Nucleon Polarizabilities

abstract:
  Compton scattering offers in principle an intriguing new window on nucleon
structure. Existing experiments and future programs are discussed and the state
of theoretical understanding of such measurements is explored.


title: Damping rate for transverse gluons with finite soft momentum in hot QCD

abstract:
  We calculate the damping rate for transverse gluons with {\nineti finite}
soft momentum to leading order in perturbative hot QCD. The internal momenta of
the one-loop contributing diagrams are soft. This means we have to use
effective vertices and propagators which incorporate the so-called hard thermal
loops. We expand the damping rate in powers of the incoming momentum and argue
that the series ought to converge within a finite radius of convergence. We
contrast such a behavior with the one obtained from a previous calculation that
produced a logarithmic behavior, a calculation based on letting the gluon
momentum come from the hard limit down towards the interior of the soft region.
This difference in behavior may point to interesting physics around some
`critical' region.


title:
Short Distance Coefficients and the Vanishing of the Lepton Asymmetry in
  $B\to V\ell^+\ell^-$

abstract:
  We derive a condition the short distance coefficients governing $b\to
(s,d)\ell^+\ell^-$ transitions must satisfy in order for the forward-backward
asymmetry to vanish in the exclusive modes $B\to (K^*,\rho)\ell^+\ell^-$. This
relation, which is satisfied in the standard model, involves the coefficient
entering in $b\to s\gamma$ transitions as well as one of the additional Wilson
coefficients present in the leptonic modes. We show that the resulting relation
is largely free of hadronic uncertainties, thus constituting a reliable test of
the standard model in exclusive rare B decays.


title: CP Violation

abstract:
  In this lecture I review the present status of CP violation in the Standard
Model and some of its extensions and discuss ways to distinguish different
models.
  Contents
  1. Introduction 2. CP violation in the Standard Model 3. Test the Standard
Model in B decays 4. Models for CP violation 5. The KM unitarity triangle and
new physics 6. Direct CP violation in neutral Kaon system 7. The electric
dipole moment 8. Partial rate asymmetry 9. Test of CP violation involving
polarization measurement 10. Baryon number asymmetry 11. Conclusion


title:
Hybrid $SU(2)\times U(1)$ models, electric charge nonconservation and
  the photon mass

abstract:
  Hybrid $SU(2) \times U(1)$ models are the models in which $SU(2) \times U(1)$
symmetry is broken down not only spontaneously (as in the Standard Model), but
also explicitely by adding a hard mass term for the U(1) field in the
lagrangian. We study the issue of electric charge nonconservation and
dequantization in these models. For this purpose we construct and analyze a
series of hybrid models with different scalar contents. We show that some of
these models posess an interesting property: the photon can remain massless (at
least, at the tree level) even though the electric charge is not conserved.


title: Dirac magnetic monopole and the discrete symmetries

abstract:
  We examine several issues related to the processes of Dirac
monopole-antimonopole production in high-energy collisions such as $e^+e^-$
annihilation. Perturbative calculations for such processes are known to be
inherently ambiguous due to the arbitrariness of direction of the monopole
string; this requires use of some prescription to obtain physical results. We
argue that different prescriptions lead to drastically different physical
results which suggests that at present we do not have an entirely satisfactory
procedure for the elimination of string arbitrariness (this problem is quite
separate from the problems caused by the large coupling constant). We then
analyze the consequencies of discrete symmetries (P and C) for the monopole
production processes and for the monopole-antimonopole states. The P and C
selection rules for the monopole-antimonopole states turn out to be different
from those for the ordinary fermion-antifermion or boson-antiboson system. In
particular, the spin 1/2 monopole and antimonopole should have the same
helicities if they are produced through the one-photon annihilation of an
electron and positron. A stronger selection rule holds for spinless monopoles:
CP symmetry absolutely forbids the monopole-antimonopole production through the
one-photon annihilation of an electron and positron. Single-photon $e^+e^- \to
g^+g^-$ amplitude has been a key input in calculating the contribution of
virtual $g^+g^-$ pairs to various physical processes such as the decay $Z\to
3\gamma$ and the anomalous magnetic moment of the electron. Applying our
conclusions to these cases can lead to significant modifications of the results
obtained in previous works.


title:
Chiral symmetry amplitudes in the S-wave isoscalar and isovector
  channels and the sigma, f_0(980), a_0(980) scalar mesons (HADRON'97)

abstract:
  We use a non-perturbative approach which combines coupled channel
Lippmann-Schwinger equations with meson-meson potentials provided by the lowest
order chiral Lagrangian. By means of one parameter, a cut off in the momentum
of the loop integrals, which results of the order of 1 GeV, we obtain
singularities in the S-wave amplitudes corresponding to the sigma, f_0 and a_0
resonances. The \pi\pi --> \pi\pi, \pi\pi --> K bar(K) phase shifts and
inelasticities in the T=0 scalar channel are well reproduced as well as the
\pi^0 eta and K bar(K) mass distributions in the T=1 channel. Furthermore, the
total and partial strong decay widths of the f_0 and a_0 resonances are
properly reproduced.


title: Report of the Working Group on Goldstone Boson Production and Decay

abstract:
  This is the summary of the working group on Goldstone Boson Production and
Decay of the Chiral Dynamics Workshop in Mainz, September 1-5, 1997. For the
production aspects we discuss $\pi^0$ and $\eta$ production in nucleon-nucleon
collisions and the behaviour of hadrons in various sum rules. For the decays we
present a discussion on various $K$, $\eta$ and $\pi$ decay channels. Other
aspects discussed are a new treatment of meson-meson scattering, the
light-by-light contribution to the muon anomalous magnetic moment and progress
in various aspects of the $p^6$ generating functional in the mesonic sector.


title: Operator product expansion at finite temperature

abstract:
  We extend an earlier, configuration space method to find the Wilson
coefficients of operators appearing in the short distance expansion of thermal
correlation functions of different quark bilinears. Considering all the
different correlation functions, there arise, up to dimension four, two new
operators, in addition to the two appearing already in the vacuum correlation
functions. They would contribute substantially to the QCD sum rules, when the
temperature is not too low.


title: Theoretical Study of the \gamma\gamma-->meson-meson Reaction (HADRON'97)

abstract:
  We present a unified picture which studies simultaneously the gamma gamma-->
pi^+ pi^-, pi^0 pi^0,K^+ K^-, K^0 bar{K}^0, pi^0 eta reactions up to about
sqrt(s)=1.4 GeV reproducing the experimental cross sections. The present work
implements in an accurate way the final state interactions of the meson-meson
system, which is shown to be essential in order to reproduce the data,
particularly the L=0 channel. This latter channel is treated here following a
recent theoretical work in which the meson-meson amplitudes are well reproduced
and the f_0, a_0, sigma resonances show up clearly as poles of the t matrix.
The present work, as done in earlier ones, also incorporates elements of chiral
symmetry and exchange of vector and axial resonances in the crossed channels,
as well as a direct coupling to the f_2(1270) and a_2(1320) resonances. We also
evaluate the decay width of the f_0(980) and a_0(980) resonances into the
gamma-gamma channel.


title: Non-perturbative Dynamics of the Heavy-Light Quark System

abstract:
  We obtain the non-perturbative interaction kernel of the heavy-light quark
system in a gauge-invariant approach. The potential and the sum rules limit are
discussed. Some insight is given in the light quark interaction.


title: Structure Function, Final States and Angular Ordering at Small x

abstract:
  This talks examines the effect of angular ordering on the small-x evolution
of the unintegrated gluon distribution, and discusses the characteristic
function for the CCFM equation.


title: Pion-pion and pion-nucleon interactions in chiral perturbation theory

abstract:
  Elastic pion-pion and pion-nucleon scattering are reviewed in the context of
chiral perturbation theory. Theoretical results from systematic low-energy
expansions to O(p^6) for pion-pion and to O(p^3) for pion-nucleon scattering
are compared with experimental data. Possible future developments are outlined.


title:
Interference Fragmentation Functions and Valence Quark Spin
  Distributions in the Nucleon

abstract:
  We explore further applications of the twist-two quark interference
fragmentation functions introduced earlier. We show that semi-inclusive
production of two pions in the current fragmentation region in deep inelastic
scattering of a longitudinally polarized electron on a longitudinally polarized
nucleon can provide a probe of the valence quark spin (or helicity difference)
distribution in the nucleon.


title: Phenomenology of antigravity in N=2,8 supergravity

abstract:
  $N=2,8$ supergravity predicts antigravity (gravivector and graviscalar)
fields in the graviton supermultiplet. Data on the binary pulsar PSR 1913+16,
tests of the equivalence principle and searches for a fifth force yield an
upper bound of order 1 meter (respectively, 100 meters) on the range of the
gravivector (respectively, graviscalar) interaction. Hence these fields are not
important in non-relativistic astrophysics (for the weak-field limit of $N=2,8$
supergravity) but can play a role near black holes and for primordial
structures in the early universe of a size comparable to their Compton
wavelengths.


title: Radiative GUT Symmetry Breaking in a R-Symmetric Flipped SU(5) Model

abstract:
  We study the generation of the GUT scale through radiative corrections in the
context of a R-symmetric "flipped" SU(5) X U(1)_X model. A negative mass
squared term for the GUT Higgs fields develops due to radiative effects along a
flat direction at a superheavy energy scale. The R-symmetry is essential in
maintaining triplet-doublet splitting and F-flatness in the presence of
non-renormalizable terms. The model displays radiative electroweak symmetry
breaking and satisfies all relevant phenomenological constraints.


title: Prospects to detect a Z' with the LC

abstract:
  The search for a Z' is one of the tasks of future colliders. I study the
capability to detect the Z' at a linear e+e- collider operating below resonance
production. Depending on m_{\Zp} and the collider parameters we will be able to
discriminate between Z' models.


title:
Neutral-to-charged current events ratio in atmospheric neutrinos and
  neutrino oscillations

abstract:
  The atmospheric neutrinos produce isolated neutral pions ($\pi^0$-events)
mainly in the neutral current interactions. We propose to study the ratios
involving $\pi^0$-events and the events induced mainly by the charged currents.
This minimizes uncertainties related to the original neutrino fluxes, and in
certain cases, also to the cross-sections. Experimental study of these ratios
will allow one to check the oscillation solution of the atmospheric neutrino
problem and to identify the channel of oscillations. Illustrative analysis of
existing data is presented.


title: Excited Baryons Phenomenology from Large-$N_c$ QCD

abstract:
  We present a phenomenological analysis of the strong couplings of the
negative-parity L=1 baryons from the perspective of the large-$N_c$ expansion.
In the large-$N_c$ limit the mass spectrum and mixing pattern of these states
are constrained in a very specific way. The mixing angles are completely
determined in this limit, with predictions in good agreement with experiment.
In the combined large-$N_c$ and SU(3) limits the pion couplings of the five
negative-parity octets to the ground state baryons are given in terms of only 3
independent couplings. The large-$N_c$ predictions for the ratios of strong
couplings are tested against experimental data.


title: Production of neutral scalar Higgs bosons at $e\gamma$ colliders

abstract:
  We study the production of neutral scalar (CP even) Higgs bosons in the
process $e\gamma\to e h$ by including supersymmetric corrections to the
dominant $t$-channel photon exchange amplitude. In addition to the standard
model $W^{\pm}$ and fermion loops, there are substantial contributions from
chargino loops. For some cases, these contributions can exceed those of the
$W$'s and ordinary fermions. The cross sections in this channel are generally
one or two orders of magnitude larger than those in the related channel
$e\bar{e}\to\gamma h$.


title: Twist-3 contribution to the pion electromagnetic form factor

abstract:
  Non-leading contribution to the pion electromagnetic form factor which comes
from the pion twist-3 wave function is analyzed in the modified hard scattering
approach (MHSA) proposed by Li and Sterman. This contribution is enhanced
significantly due to bound state effect (the twist-3 wave function is
independent of the fractional momentum carried by the parton and has a large
factor $\sim m_\pi^2/m_0$ with $m_\pi$ being the pion meson mass and $m_0$
being the mean u- and d-quark masses). Consequently, although it is suppressed
by the factor $1/Q^2$, the twist-3 contribution is comparable with and even
larger than the leading twist (twist-2) contribution at intermediate energy
region of $Q^2$ being $2 \sim 40 {GeV}^2$.


title: Scalar sector of the 3 3 1 model with three Higgs triplets

abstract:
  A scalar sector of the 3 3 1 model with three Higgs triplets is considered.
The mass spectrum, eigenstates and interactions of the Higgs and the SM gauge
bosons are derived. We show that one of the neutral scalars can be identified
with the standard model Higgs boson, and in the considered potential there is
no mixing between scalars having VEV and ones without VEV.


title: Theoretical advances in lattice QCD

abstract:
  The past few years have seen many interesting theoretical developments in
lattice QCD. This talk (which is intended for non-experts) focuses on the
problem of non-perturbative renormalization and the question of how precisely
the continuum limit is reached. Progress in these areas is crucial in order to
be able to compute quantities of phenomenological interest, such as the hadron
spectrum, the running quark masses and weak transition matrix elements, with
controlled systematic errors.


title: Electron neutrino opacity in magnetised media

abstract:
  We study the effects of strong magnetic fields ($B> 10^{13}$~G) in the cross
section for $\nu_e n\to p e$ scattering in the presence of a degenerate
electron background. This can be relevant for the $\nu_e$ propagation in the
proto-neutron star stage after supernovae collapse. We find that for field
strengths $B> 10^{16}$~G$(E_\nu/10$ MeV$)^2$ the $\nu_e$ opacity is sizeably
affected by the magnetic field and can lead to a shift in the location of the
electron neutrino sphere towards lower densities.
  We discuss the implications that this may have for scenarios proposed to
explain the observed pulsar velocities.


title:
Isgur-Wise form factors of heavy baryons within a light-front
  constituent quark model

abstract:
  The space-like elastic form factors of baryons containing a heavy quark are
investigated within a light-front constituent quark model in the limit of
infinite heavy-quark mass, adopting a gaussian-like ansatz for the three-quark
wave function. The results obtained for the Isgur-Wise form factors
corresponding both to a spin-0 and a spin-1 light spectator pair are presented.
It is found that the Isgur-Wise functions depend strongly on the baryon
structure, being sharply different in case of diquark-like or collinear-type
configurations in the three-quark system. It is also shown that the
relativistic effects lead to a saturation property of the form factors as a
function of the baryon size. Our results are compared with those of different
models as well as with recent predictions from QCD sum rules and lattice QCD
simulations; the latter ones seem to suggest the dominance of collinear-type
configurations, in which the heavy-quark is sitting close to the center-of-mass
of the light quark pair.


title: Baryon Asymmetry of the Universe and Lepton Mixing

abstract:
  Baryogenesis appears to require lepton number violation. This is naturally
realized in extensions of the standard model containing right-handed neutrinos.
We discuss the generation of a baryon asymmetry by the out-of-equilibrium decay
of heavy Majorana neutrinos in these models, without and with supersymmetry.
All relevant lepton number violating scattering processes which can inhibit the
generation of an asymmetry are taken into account. We assume a similar pattern
of mixings and masses for neutrinos and up-type quarks, as suggested by SO(10)
unification. This implies that B-L is broken at the unification scale
$\Lambda_{GUT}\sim 10^{16}$ GeV, if $m_{\nu_\mu} \sim 3\cdot10^{-3}$ eV, as
preferred by the MSW solution to the solar neutrino deficit. The observed
baryon asymmetry is then obtained without any fine tuning of parameters.


title: Reexamination of the resonance contributions in B->X_s e^+ e^-

abstract:
  With help of the recent developments in the heavy quarkonium physics, we
reexamine the long distance(LD) effects in \Bsee dominantly from the charmonium
resonances $J/\Psi$ and $\Psi^{\prime}$ through the decay chains $B\ra X_s
J/\Psi (\Psi^{\prime}) \ra X_s e^+ e^-$. We find that the resonance to
nonresonance interference are reduced substantially.


title: Analysis of K_L -> pi^+ pi^- gamma in Chiral Perturbation Theory

abstract:
  We study the long-distance dominated K_L -> pi^+ pi^- gamma decay at O(p^6)
in Chiral Perturbation Theory. The complete calculation of the O(p^6) loop
magnetic amplitude is carried out. At this chiral order the model dependent
part of the vector meson exchange contribution to the magnetic amplitude is
evaluated in the two models : FM (Factorization Model) and FMV (Factorization
Model in the Vector Couplings). We predict, in an almost model independent way,
a slope of K_L -> pi^+ pi^- gamma in the range c = -1.6,-1.8, consistently with
the experimental value. We find that the experimental result for the width of
K_L -> pi^+ pi^- gamma is compatible with a bigger breaking of the nonet
symmetry in the weak vertices than previously stated. Thus we conclude that our
analysis does not exclude an opposite sign to the one given by the dominance of
the pion pole in the poorly known K_L -> gamma gamma amplitude. A complete
analysis of the O(p^3) weak Vector-Pseudoscalar-Pseudoscalar (VPP) vertex is
also performed.


title:
Spin-1 resonance contributions to the weak Chiral Lagrangian: the vector
  field formulation

abstract:
  We use the Vector formulation to evaluate vector and axial-vector exchange
contributions to the O(p^4) weak Chiral Lagrangian. We recover in this
framework the bulk of the contributions found previously by Ecker et al. in the
antisymmetric formulation of vectors and axial-vectors, but new interesting
features arise: i) most of our results are independent of Factorization and ii)
novel contributions to non-leptonic kaon decays, proper of this formulation and
phenomenologically interesting, are found. The phenomenological implications
for K -> pi pi (pi) and radiative (anomalous and non-anomalous) non-leptonic
kaon decays are thus investigated and found particularly relevant.


title: Bose-Einstein and Colour Interference in W-pair Decays

abstract:
  We study effects on the W mass measurements at LEP2 from non-perturbative
interference effects in the fully hadronic decay channel. Based on a model for
Bose-Einstein interference, which is in agreement with LEP1 data, we argue that
there are no Bose-Einstein correlations between bosons coming from the
different W's. For small reconnection probabilities we rule out the possible
experimental signal of colour interference at LEP2, suggested in previous work.
The conclusions from this paper are that the theoretical uncertainties in the W
mass determination should be smaller than the experimental statistical error.


title: Photon and Dilepton Production from Hot Out-Off-Equilibrium Media

abstract:
  The electromagnetic emissivity from QCD media away from equilibrium is
studied in the framework of closed time path thermal field theory. For the
dilepton rate a nonequilibrium mesonic medium is considered applying finite
temperature perturbation theory for $\pi -\rho$ interactions. The dilepton rate
is derived up to the order $g_\rho^2$. For hard photon production a quark gluon
plasma is assumed and calculations are performed in leading order in the strong
coupling constant. These examples are chosen in order to investigate the role
of possible pinch terms in boson and in fermion propagators, respectively. The
implications of the results for phenomenology are also discussed.


title: Quasi-open inflation

abstract:
  We show that a large class of two-field models of single-bubble open
inflation do not lead to infinite open universes, as it was previously thought,
but to an ensemble of very large but finite inflating `islands'. The reason is
that the quantum tunneling responsible for the nucleation of the bubble does
not occur simultaneously along both field directions and equal-time
hypersurfaces in the open universe are not synchronized with equal-density or
fixed-field hypersurfaces. The most probable tunneling trajectory corresponds
to a zero value of the inflaton field; large values, necessary for the second
period of inflation inside the bubble, only arise as localized fluctuations.
The interior of each nucleated bubble will contain an infinite number of such
inflating regions of comoving size of order $\gamma^{-1}$, where $\gamma$
depends on the parameters of the model. Each one of these islands will be a
quasi-open universe. Since the volume of the hyperboloid is infinite, inflating
islands with all possible values of the field at their center will be realized
inside of a single bubble. We may happen to live in one of those patches of
comoving size $d\lesssim \gamma^{-1}$, where the universe appears to be open.
In particular, we consider the ``supernatural'' model proposed by Linde and
Mezhlumian. There, an approximate U(1) symmetry is broken by a tunneling field
in a first order phase transition, and slow-roll inflation inside the nucleated
bubble is driven by the pseudo-Goldstone field. We find that the excitations of
the pseudo-Goldstone produced by the nucleation and subsequent expansion of the
bubble place severe constraints on this model. We also discuss the coupled and
uncoupled two-field models.


title:
Probing the Flavor and CP Structure of Supersymmetric Models with K -->
  pi nu nubar Decays

abstract:
  We study the implications of various supersymmetric models on the rare $K^+
\to \pi^+ \nu \bar\nu$ and $K_L \to \pi^0 \nu \bar\nu$ decays. Although large
effects are possible in generic supersymmetric models, most of the known
supersymmetric flavor models lead to negligible effects. Thus, it is likely
that one can get information about CKM matrix elements from these decays even
in the presence of supersymmetry. Moreover, the possibility of large
contributions to $K \to \pi \nu \bar\nu$ in generic supersymmetric models can
be constrained by improved bounds on $D-\bar D$ mixing. We show that it may be
possible to distinguish between different supersymmetric flavor models by
combining the information from the $K \to \pi \nu \bar\nu$ decays with that
from $B-\bar B$ and $D-\bar D$ mixing.


title: Multilepton signatures of gauge mediated SUSY breaking at LEPII

abstract:
  In the framework of gauge-mediated supersymmetry breaking models pair
production of the lightest neutralinos, scalar leptons, or charginos at LEPII
gives rise to interesting signals involving multilepton final states and
missing energy. In the parameter space where the scalar tau, $\tilde{\tau}_1$,
is the next-to-lightest supersymmetric particle, we identify three interesting
regions, which give rise to distinctly different final states: (i) 2
$\tau$-leptons plus missing energy, (ii) 4 charged leptons plus missing energy
where in some regions all four are $\tau$-leptons, or (iii) six charged
leptons, of which four are $\tau$-leptons and the other two are electrons or
muons, plus missing energy. We study in detail the size of these regions in the
parameter space of gauge-mediated models and give cross section contours in
these regions for various LEPII energies. We also discuss the possibility of
chargino-pair production at LEPII.


title: CKM Matrix: Present and Future

abstract:
  We review the present status of the CKM matrix and we offer some visions of
its future. After a brief presentation of the theoretical framework for weak
decays we discuss the following topics: i) CKM matrix from tree level decays,
ii) Standard analysis of the unitarity triangle, iii) CKM matrix from rare and
CP violating K- and B-decays, iv) CKM matrix from CP violation in two-body
B-decays. In particular we compare the CKM potentials of the standard analysis
of the unitarity triangle, of the very clean K --> \pi\nu\bar\nu decays and of
CP asymmetries in B-decays.


title: Long-Lived Quarks?

abstract:
  Several lines of reasoning suggest that there might exist a non-sequential
fourth generation of heavy quarks having very small mixing with light quarks
and hence exceptionally long lifetime.


title: Higher Order Renormalons

abstract:
  A systematic method of summing the corrections to the renormalon residue
arising from higher order renormalons is discussed.


title:
A Gauge Mediation Model of Dynamical Supersymmetry Breaking without
  Color Instability

abstract:
  We construct a gauge mediation model of dynamical supersymmetry breaking
(DSB) based on a vector-like gauge theory, in which there is a unique
color-preserving true vacuum. The DSB scale $\Lambda/4\pi$ turns out to be as
high as $\Lambda/4\pi \simeq 10^{8-9} GeV$, since the transmission of the DSB
effects to the standard model sector is completed through much higher loops.
This model is perfectly natural and phenomenologically consistent. We also
stress that the dangerous D-term problem for the messenger U(1)_m is
automatically solved by a charge conjugation symmetry in the vector-like gauge
theory.


title:
Finite-temperature reaction-rate formula: Finite volume system, detailed
  balance, $T \to 0$ limit, and cutting rules

abstract:
  A complete derivation, from first principles, of the reaction-rate formula
for a generic process taking place in a heat bath of finite volume is given. It
is shown that the formula involves no finite-volume correction. Through
perturbative diagrammatic analysis of the resultant formula, the
detailed-balance formula is derived. The zero-temperature limit of the formula
is discussed. Thermal cutting rules, which are introduced in previous work, are
compared with those introduced by other authors.


title: Nucleon-Nucleon Interaction and Isospin Violation

abstract:
  The application of the chiral effective theory to processes with two or more
nucleons is discussed. We gain a qualitative understanding of the gross
features of nuclear physics and quantitative, testable postdictions and
predictions involving photons and pions.


title: A Practical Procedure for Evolving Heavy Flavour Structure Functions

abstract:
  The transition from the low $Q^2$ region in deep inelastic scattering where
charm production is described by photon-gluon fusion to a region where the
charm structure function $F_2^c$ is largely generated by a charm quark density
should be a smooth passage. The all orders prescription for matching between
the two schemes does not uniquely determine all the relevant coefficient
functions (CF's) or guarantee the correct threshold behaviour at fixed order in
$\alpha_s$. The constraints of matching not only the value but also the
evolution of $F_2^c$ order by order allows all CF's to be determined at any
order, each of which reduces to the appropriate massless $\msb$ expression as
$Q^2 \to \infty$, and leads to a smooth transition in the threshold region.
This procedure gives an excellent description of the $F_2^c$ data for all
$Q^2$.


title: Theory of Jets in Deep Inelastic Scattering

abstract:
  The large center of mass energy and increasing statistical precision for a
wide range of hadronic final state observables at the HERA lepton-proton
collider has provided a detailed testing ground for QCD dynamics. Fully
flexible next-to-leading order calculations are mandatory on the theoretical
side for such tests and will be discussed in detail. Next-to-leading order QCD
predictions for one- and two-jet cross sections in deep inelastic scattering
with complete neutral current ($\gamma^\ast$ and/or $Z$) and charged current
($W^\pm$) exchange together with leading order results for three- and four-jet
final states are presented. The theoretical framework, based on the phase space
slicing method and the use of universal crossing functions, is described in
detail. All analytical formulae necessary for the next-to-leading order
calculations are provided. The numerical results are based on the fully
differential $ep \to n$ jets event generator \docuname which allows to analyze
any infrared and collinear safe observable and general cuts in terms of parton
4-momenta. The importance of higher order corrections is studied for various
jet algorithms. Implications and comparisons with (ongoing) experimental
analyses for jet cross sections at high $Q^2$, the determination of
$\alpha_s(\mu_R)$, the gluon density, power corrections in event shapes and the
associated forward jet production in the low $x$ regime at HERA are discussed.
A study of jet cross sections in polarized electron and polarized proton
collisions shows that dijet events provide a good measurement of the polarized
gluon distribution $\Delta g(x_g)$, in a region, where $x_g \Delta g(x_g)$ is
expected to show a maximum.


title: Double parton scatterings in high energy hadronic collisions

abstract:
  CDF has recently measured a large number of double parton scatterings. The
observed value of $\sigma_{eff}$, the non perturbative parameter which
characterizes the process, is considerably smaller as compared with the naive
expectation. The small value of $\sigma_{eff}$ is likely to be an indication of
the importance of the two-body parton correlations in the many-body parton
distributions of the proton.


title: Instantons and Polarized Structure Functions

abstract:
  The contribution of the quark-quark and quark-gluon interaction induced by
instantons to the valence quark and proton spin-dependent structure functions
$g_1(x,Q^2)$ is estimated within the instanton liquid model for QCD vacuum. It
is shown, that this interaction leads to a rather large violation of the
Ellis-Jaffe sum rule.


title: Hard Exclusive Meson Production and Nonforward Parton Distributions

abstract:
  We present an analysis of twist-2, leading order QCD amplitudes for hard
exclusive leptoproduction of mesons in terms of double/nonforward parton
distribution functions. After reviewing some general features of nonforward
nucleon matrix elements of twist-2 QCD string operators, we propose a
phenomenological model for quark and gluon nonforward distribution functions.
The corresponding QCD evolution equations are solved in the leading logarithmic
approximation for flavor nonsinglet distributions. We derive explicit
expressions for hard exclusive pi^0, eta, and neutral vector meson production
amplitudes and discuss general features of the corresponding cross sections.


title:
O(\alpha) QED Corrections to Polarized Elastic $\mu e$ and Deep
  Inelastic l N Scattering

abstract:
  Two computer codes relevant for the description of deep inelastic scattering
off polarized targets are discussed. The code ${\mu}$ela deals with radiative
corrections to elastic $\mu e$ scattering, one method applied for muon beam
polarimetry. The code HECTOR allows to calculate both the radiative corrections
for unpolarized and polarized deep inelastic scattering, including higher order
QED corrections.


title: The $\eta - \eta'$ Mixing Angle Revisited

abstract:
  The value of the $\eta - \eta'$ mixing angle $\theta_P$ is phenomenologically
deduced from a rather exhaustive and up-to-date analysis of data including
strong decays of tensor and higher-spin mesons, electromagnetic decays of
vector and pseudoscalar mesons, $J/\psi$ decays into a vector and a
pseudoscalar meson, and other transitions. A value of $\theta_P$ between
$-17^\circ$ and $-13^\circ$ is consistent with all the present experimental
evidence and the average $\theta_P=-15.5^\circ\pm 1.3^\circ$ seems to be
favoured.


title: Magnetic and Thermodynamic Stability of SU(2) Yang-Mills Theory

abstract:
  SU(2) Yang-Mills theory at finite extension or, equivalently, at finite
temperature is probed by a homogeneous chromomagnetic field. We use a recent
modified axial gauge formulation which has the novel feature of respecting the
center symmetry in perturbation theory. The characteristic properties of the
Z_2-symmetric phase, an extension-dependent mass term and antiperiodic boundary
conditions, provide stabilization against magnetic field formation for
sufficiently small extension or high temperature. In an extension of this
investigation to the deconfined phase with broken center symmetry, the combined
constraints of thermodynamic and magnetic stability are shown to yield many of
the high temperature properties of lattice SU(2) gauge theory.


title:
Flavor Symmtry Breaking andd Mixing Effects in the eta-gamma and
  eta'-gamma Transition Form Factors

abstract:
  We reanalyze the eta-gamma and eta'-gamma transition form factors within the
modified hard scattering approach on the basis of new experimental data from
CLEO and L3. Our approach perfectly describes the experimental data over a wide
range of the virtuality of the probing photon, 1 GeV^2 < Q^2 < 15 GeV^2. The
analysis provides hints that the conventional flavor octet-singlet scheme for
the eta-eta' mixing is too simple. A more general mixing scheme on the other
hand, involving two mixing angles, leads to a very good description of the
transition form factors and also accounts for the two-photon decay widths of
the eta and eta' mesons as well as for the ratio of the widths for the J/Psi
--> eta' gamma and J/Psi --> eta gamma decays. We also investigate the
questions of possible deviations of the eta and eta' distribution amplitudes
from the asymptotic form and of eventual intrinsic charm in the eta and eta'
mesons. We estimate the charm decay constant of the eta' meson to lie within
the range -65 MeV < fc(eta') <15 MeV.


title: Unified theories

abstract:
  The present status of Unified Theories is summarized with special emphasis on
their possible experimental tests. Outline: i) Unification of couplings; ii)
Where can a positive signal come from? iii) HERA anomaly and Unification; iv)
Recent progress in model building; v) Flavour and Unification.


title: Top Quark Pair Production and Decay Near Threshold in e+e- Collisions

abstract:
  We review the physics involved in the production and decay of top quarks in
e^+e^- -> ttbar near threshold, with special emphasis on the recent theoretical
study on the decay process of top quarks in the threshold region. The
energy-angular distribution of l^+ in semileptonic top decays is calculated
including the full O(alpha_s) corrections. Various effects of the final-state
interactions are elucidated. A new observable is defined near threshold, which
depends only on the decay of free polarized top quarks, and thus it can be
calculated without bound-state effects or the final-state interactions.


title:
Probing top quark decay into light stop in the supersymmetric standard
  model at the upgraded Tevatron

abstract:
  We investigate the possibility of observing the exotic decay mode of the top
quark into the lightest stop ($\tilde t_1$) and neutralino ($\tilde\chi^0_1$)
in the minimal supersymmetric standard model with R-parity at the upgraded
Tevatron. First we determine the allowed range for the branching fraction
$B(t\to \tilde t_1 \tilde\chi^0_1)$ in the region of parameter space allowed by
the $R_b$ data and the CDF $ee\gamma\gamma+{\large \not} E_T$ event, and then
consider all possible backgrounds and investigate the possibility of observing
this final state at the Tevatron. We find that this final state is unobservable
at Run 1. However, Run 2 can provide significant information on this new decay
mode of the top quark: either discover it, or establish a strong constraint on
the masses of $\tilde t_1$ and $\tilde\chi^0_1$ given approximately by
$M_{\tilde \chi^0_1} > M_{\tilde t_1} - 6$ GeV.


title: Time Evolution of Unstable Particle Decay Seen with Finite Resolution

abstract:
  Time evolution of the decay process of unstable particles is investigated in
field theory models. We first formulate how to renormalize the non-decay
amplitude beyond perturbation theory and then discuss short-time behavior of
very long-lived particles. Two different formalisms, one that does and one that
does not, assume existence of the asymptotic field of unstable particles are
considered. The non-decay amplitude is then calculated by introducing a finite
time resolution of measurement, which makes it possible to discuss both
renormalizable and non-renormalizable decay interaction including the nucleon
decay. In ordinary circumstances the onset of the exponential decay law starts
at times as early as at roughly the resolution time, but with an enhanced
amplitude which may be measurable. It is confirmed that the short-time formula
$1 - \Gamma t$ of the exponential decay law may be used to set limits on the
nucleon decay rate in underground experiments. On the other hand, an
exceptional example of S-wave decay of very small Q-value is found, which does
not have the exponential period at all.


title: High-mass diffraction in the QCD dipole picture

abstract:
  Using the QCD dipole picture of the BFKL pomeron, the cross-section of single
diffractive dissociation of virtual photons at high energy and large
diffractively excited masses is calculated. The calculation takes into account
the full impact-parameter phase-space and thus allows to obtain an exact value
of the triple BFKL Pomeron vertex. It appears large enough to compensate the
perturbative 6-gluon coupling factor (alpha/pi)^3 thus suggesting a rather
appreciable diffractive cross-section.


title: Nuclear Effects on Charmonium Production

abstract:
  $J/\psi$ and $\psi'$ production cross sections in fixed-target experiment is
calculated, considering the contributions from both color-singlet and
color-octet mechanisms.The results are applied to the investigations of the
$J/\psi$ suppression and the $\psi'/\psi$ ratio problems in p-A collisions. The
results agree with the experimental data as the $(c \bar c)-$nucleon absorption
cross sections $\sigma_{abs}^8\simeq 10mb $ for $(c \bar c)_8$ and
$\sigma_{abs}^1\simeq 0mb $ for $(c \bar c)_1$. The model is further used to
investigate A-A collisions when comover absorption mechanism is also
considered. It is found that the observed experiment data of $J/\psi$ and
$\psi'/\psi$ ratio in S-U collisions and Pb-Pb collisions can not be explained
consistently within this model. The possibility of QGP formation in S-U and
Pb-Pb collisions is also discussed.


title:
Two-loop hybrid renormalization of local dimension-4 heavy-light
  operators

abstract:
  The renormalization of local dimension-4 operators containing a heavy and a
light quark field at scales below the heavy-quark mass is discussed, using the
formalism of the heavy-quark effective theory. The anomalous dimensions of
these operators and their mixing are calculated to two-loop order. Some
phenomenological applications are briefly discussed.


title: 1/m_Q corrections in heavy meson decays

abstract:
  We study the form factor f_+^H (H=D,B) involved in H-\pi transitions. We use
data on D^0 \to \pi^- l^+ \nu to find f_+^D at low recoil. Then we use
perturbative QCD methods to calculate at larger recoil the contributions to
f_+^H that break heavy quark symmetry (HQS). Using HQS relations we obtain an
estimate of f_+^B which includes first order corrections in 1/(2m_Q).
Comparison with recent data on B^0 \to \pi^- l^+ \nu gives V_ub = 0.0025 \pm
0.0005^ex \pm 0.0004^th.


title: Completely positive dynamics of correlated neutral kaons

abstract:
  We study the behaviour of correlated neutral kaons produced in phi-meson
decays under the hypothesis that the quantum mechanical time-evolution is
completely positive. We show that planned experiments at phi-factories could
give precise bounds on the phenomenological parameters of the model.


title: Strong Decays of Hybrid Mesons from the Heavy Quark Expansion of QCD

abstract:
  We calculate the strong decays of hybrid mesons to conventional mesons for
all the lowest lying J^PC hybrids of flavour uu, dd, ss, cc and bb. A decay
operator developed from the heavy quark expansion of quantum chromodynamics is
employed. We show that the selection rule that hybrid mesons do not decay to
identical S-wave mesons, found in other models, is preserved. We predict decays
of charmonium hybrids, discuss decays of J^PC=1^-+ exotic isovector hybrids of
various masses, and interpret the \pi(1800) as a hybrid meson.


title: Towards a Complete Calculation of $\gamma\gamma \to 4f$

abstract:
  We present a general classification of all four fermion final states in
$\gamma\gamma$~collisions and a calculation of cross sections below the
$W^+W^-$-threshold.


title: Non-perturbative renormalization of QCD

abstract:
  In these lectures, we discuss different types of renormalization problems in
QCD and their non-perturbative solution in the framework of the lattice
formulation. In particular the recursive finite size methods to compute the
scale-dependence of renormalized quantities is explained. An important
ingredient in the practical applications is the Schr\"odinger functional. It is
introduced and its renormalization properties are discussed.
  Concerning applications, the computation of the running coupling and the
running quark mass are covered in detail and it is shown how the
$\Lambda$-parameter and renormalization group invariant quark mass can be
obtained. Further topics are the renormalization of isovector currents and
non-perturbative Symanzik improvement.


title:
Higgs Boson Production in Association with Scalar Top Quarks at Proton
  Colliders

abstract:
  We investigate the production of Higgs particles in association with the
supersymmetric scalar partners of the top quark at proton colliders. In the
minimal supersymmetric extension of the Standard Model, the cross sections for
the production of the lightest neutral Higgs boson in association with top
squark pairs can be rather large, substantially exceeding the rate for the
associated Higgs boson production with top quarks. If the lightest top squark
is not much heavier than the top quark, this process will enhance the potential
of the CERN Large Hadron Collider to discover the lightest neutral Higgs boson,
and will open a window to the study of the Higgs-stop coupling, the potentially
largest electroweak coupling in the supersymmetric theory.


title: Spin Structure Functions from Lattice QCD

abstract:
  We report on new results of the spin dependent structure functions $g_1$ and
$h_1$ of the nucleon. An attempt is made to convert the moments, which is what
one computes on the lattice, to quark distribution functions.


title: Weak Phase $\gamma$ From Ratio of $B \to K \pi$ Rates

abstract:
  The ratio of partial decay rates for charged and neutral $B$ mesons to $K
\pi$ final states provides information on the weak phase $\gamma \equiv {\rm
Arg} (V_{ub}^*)$ when augmented with information on the CP-violating asymmetry
in the $K^\pm \pi^\mp$ mode. The requirements for a useful determination of
$\gamma$ are examined in the light of present information about the decays $B^0
\to K^+ \pi^-$, $B^+ \to K^0 \pi^+$, and the corresponding charge-conjugate
modes. The effects of electroweak penguins and rescattering corrections are
noted, and proposals are made for estimating and measuring their importance.


title: Forward scattering amplitude of the virtual longitudinal photon in QED

abstract:
  Forward scattering amplitude of the virtual longitudinal photon at zero
energy on electron in QED in the limit of small photon virtualities is
calculated. The first radiation corrections are taken into account. Two terms
in the expansion over photon virtualities are obtained.


title: Comment on $V_{ub}$ from Exclusive Semileptonic B and D Decays

abstract:
  The prospects for determining $|V_{ub}|$ from exclusive B semileptonic decay
are discussed. The double ratio of form factors $(f^{B\to\rho}/f^{B\to K^*})/
(f^{D\to\rho}/f^{D\to K^*})$ is calculated using chiral perturbation theory.
Its deviation from unity due to contributions that are non-analytic in the
symmetry breaking parameters is very small. Combining experimental data
obtainable from (B->rho l nu), (B->K* l l) and (D->rho l nu) can lead to a
model independent determination of $|V_{ub}|$ with an uncertainty from theory
of about 10%.


title: Tau Neutrino Decays and Big Bang Nucleosynthesis

abstract:
  We investigate the non-radiative decay during nucleosynthesis of a massive
tau neutrino with mass 0.1 - 1 MeV into an electron neutrino and a scalar or
pseudoscalar particle, $\phi$. The full Boltzmann equation is used and shown to
give markedly different results than the usual non-relativistic formalism for
relativistic or semi-relativistic neutrino decays. Indeed, the region we
investigate is where the formalism that has previously been applied to solving
this problem is expected to break down. We also compare the nucleosynthesis
predictions from this scenario with results from the standard model and with
some of the available observational determinations of the primordial
abundances. It is found that for relativistic or semi-relativistic decays the
helium abundance can be significantly lowered without changing other light
element abundances. Since a problem with the standard model of Big Bang
nucleosynthesis is that helium appears to be overproduced, a decay of the type
we discuss can be a possible solution.


title: Photoproduction Processes in Polarized ep - Collisions at HERA

abstract:
  We study various conceivable photoproduction reactions in a polarized ep
collider mode of HERA with respect to their sensitivity to the proton's
polarized gluon distribution. A special emphasis is put on the `resolved' part
of the cross sections which in principle opens the possibility to determine for
the first time also the completely unknown parton content of longitudinally
polarized photons. In the very promising case of dijet production we also
investigate the impact of parton showering, hadronization and jet finding on
the parton level results.


title:
Analytic Approach to Perturbative QCD and Renormalization Scheme
  Dependence

abstract:
  We further develop the approach recently used to construct an analytic
ghost-free model for the QCD running coupling based on the requirement of the
$Q^2$-analyticity and apply it to the process of $e^+e^-$ annihilation into
hadrons to study the renormalization scheme dependence of the $R(s)$
cross-section ratio. \par By transforming the relevant QCD corrections up to
the three-loop level into the "analytized" form we show that the $R_{AA}(s)$
expression thus obtained is remarkably stable (as compared to the conventional
perturbative approach) with respect to the renormalization scheme dependence
for the whole low-energy region.


title: Exchange Current Contributions to the Charge Radii of the Nucleons

abstract:
  The exchange charge density operators that correspond to the Fermi-invariant
decomposition of quark-quark interactions have been constructed. Their effect
on the electromagnetic charge radii of the nucleons, in combination with that
of the relativistic corrections to the single-quark operator, has been studied
with a constituent quark model with a spin and flavor dependent hyperfine and a
linear confining interaction, which gives a quantitative description of the
spectra for the light and strange baryons. The model gives proton and neutron
charge radii in approximate agreement with the empirical results assuming
reasonable values for the radii of the constituent quarks.


title: Single Top and Light Higgs at TeV Energy $\gamma e$ Colliders

abstract:
  Results of complete tree level calculation of the single top and light Higgs
production in the reaction $\gamma e \to \nu b \bar{b} W$ at the Next Linear
Collider are presented. In addition, the contributions of anomalous operators
to the $Wtb$ and $WWH$ couplings are included into the complete 4-body
consideration. The sensitivity for probing the structure of the couplings in a
model independent way is analyzed.


title:
Higher-order corrections to precision observables in the Standard Model
  and the MSSM

abstract:
  A summary of recent results obtained for higher-order corrections to
precision observables in the Standard Model and the Minimal Supersymmetric
Standard Model is given. In the Standard Model electroweak two-loop results
valid for arbitrary values of the masses of the top quark, the Higgs boson and
the gauge bosons are discussed. For the example of two specific diagrams the
exact two-loop result is compared with the result of an expansion in the
top-quark mass up to next-to-leading order. Furthermore the Higgs-mass
dependence of the two-loop corrections to the relation between the gauge-boson
masses is analyzed. In the MSSM the exact gluonic corrections to $\Delta r$ are
derived. They are compared with the leading contribution entering via the
$\rho$ parameter.


title:
Perturbative QCD Description of Mean Jet and Particle Multiplicities in
  e+e- annihilation

abstract:
  A complete numerical solution of the evolution equation for parton
multiplicities in quark and gluon jets with initial conditions at threshold is
presented. Data on both hadron and jet multiplicities in e+e- annihilation are
well described with a common normalization, giving further support to the
picture of Local Parton Hadron Duality. Predictions for LEP-II energies are
presented. Furthermore we study the sensitivity to the cutoff parameter Q_0 and
the scale of alpha_s.


title: The DMO Sum Rule Revisited

abstract:
  We reconsider the DMO sum rule in light of our recent two-loop calculations
of isospin and hypercharge vector and axialvector current propagators in chiral
perturbation theory. A modified derivation valid to second order in the light
quark masses is presented, and a phenomenological analysis yields determination
of a combination of finite counterterms occurring in the p^4 and p^6 chiral
lagrangians. Suggestions are given for further study.


title:
Semileptonic Lambda_b decay to excited Lambda_c baryons at order
  Lambda_{QCD}/m_Q

abstract:
  Exclusive semileptonic Lambda_b decays to excited charmed Lambda_c baryons
are investigated at order Lambda_{QCD}/m_Q in the heavy quark effective theory.
The differential decay rates are analyzed for the J^\pi=1/2^- Lambda_c(2593)
and the J^\pi=3/2^- \Lambda_c(2625). They receive 1/m_{c,b} corrections at zero
recoil that are determined by mass splittings and the leading order Isgur-Wise
function. With some assumptions, we find that the branching fraction for
Lambda_b decays to these states is 2.5-3.3%. The decay rate to the helicity \pm
3/2 states, which vanishes for m_Q \to \infty, remains small at order
Lambda_{QCD}/m_Q since 1/m_c corrections do not contribute. Matrix elements of
weak currents between a Lambda_b and other excited Lambda_c states are analyzed
at zero-recoil to order Lambda_{QCD}/m_Q. Applications to baryonic heavy quark
sum-rules are explored.


title: Non-equilibrium evolution of a `Tsunami': Dynamical Symmetry Breaking

abstract:
  We propose to study the non-equilibrium features of heavy-ion collisions by
following the evolution of an initial state with a large number of quanta with
a distribution around a momentum |\vec k_0| corresponding to a thin spherical
shell in momentum space, a `tsunami'. An O(N); ({\vec \Phi}^2)^2 model field
theory in the large N limit is used as a framework to study the
non-perturbative aspects of the non-equilibrium dynamics including a
resummation of the effects of the medium (the initial particle distribution).
In a theory where the symmetry is spontaneously broken in the absence of the
medium, when the initial number of particles per correlation volume is chosen
to be larger than a critical value the medium effects can restore the symmetry
of the initial state. We show that if one begins with such a symmetry-restored,
non-thermal, initial state, non-perturbative effects automatically induce
spinodal instabilities leading to a dynamical breaking of the symmetry. As a
result there is explosive particle production and a redistribution of the
particles towards low momentum due to the nonlinearity of the dynamics. The
asymptotic behavior displays the onset of Bose condensation of pions and the
equation of state at long times is that of an ultrarelativistic gas although
the momentum distribution is non-thermal.


title: Supersymmetric model of quasi-degenerate neutrinos

abstract:
  We present a supersymmetric model of fermion masses, based on a non-Abelian
family symmetry and the Froggatt-Nielsen mechanism, that can account for the
solar and atmospheric neutrino problems via quasi-degenerate neutrinos. The
model predicts that the ratio of neutrino mass squared splittings \Delta
m^2_{12} / \Delta m^2_{23} is of order m_s^2/m_b^2, and the angles \theta_{12}
\sim m_d/m_s and \theta_{23} \sim 1, which are of the desired orders of
magnitude. We discuss the implications of the flavor structure of the neutrino
sector on superparticle masses and mixing angles.


title: QCD Higher Order Corrections to $g_1 (x)$ at Small $x$

abstract:
  The small $x$ behavior of the flavor non-singlet $g_{1}$ structure function
is analysed numerically by taking into account the all-order resummation of
$\alpha_{s} \ln^{2}x $ terms. We include a part of the next-to-leading
logarithmic corrections coming from the resummed ``coefficient function'' which
are not considered in the literatures to respect the factorization scheme
independence. The resummed coefficient function turns out to give unexpectedly
large suppression effects over the experimentally accessible range of $x$ and
$Q^{2}$. This fact implies that the higher order logarithmic corrections are
very important for $g_{1}$ in the small $x$ region.


title:
Measurements of the $\rho$ and $\eta$ parameters of the $V_{CKM}$ matrix
  and perspectives

abstract:
  A review of the current status of the Cabibbo-Kobayashi-Maskawa matrix
($V_{CKM}$) is presented and a special emphasis is put on the determination of
the $\rho$ and $\eta$ parameters. From this study it follows that, in the
Standard Model, the $B^0_s$-$\bar{B^0_s}$ oscillation frequency, $\Delta m_s$,
has to lie, with 68% C.L., between 6.5 ps$^{-1}$ and 15 ps$^{-1}$, and is below
21 ps$^{-1}$ at 95% C.L. If the interest of measuring $\Delta m_s$ is
underlined, the importance of a precise determination of the B meson decay
constant, $f_B$, is also stressed. It is proposed to obtain a precise value for
this parameter from an accurate measurement of $f_D$, the D meson decay
constant, using results from lattice QCD to relate D and B hadrons. A future
Tau-Charm factory could accomplish this task. It is also shown that from the
present measurements, assuming the validity of the Standard Model, an already
accurate value of $sin 2\beta~=~ 0.67 ^{+0.12}_{-0.13}$ is obtained. Sofar no
constraint can be obtained on $sin 2\alpha$. The interest of having a direct
measurement of $sin 2\alpha$ and $sin 2\beta$ at B-factories or at other
facilities is reminded. Finally constraints on SUSY parameters, in the
framework of a given model, obtained from a precise measurement of the CKM
matrix elements are analyzed.


title:
Penguin Topologies, Rescattering Effects and Penguin Hunting with
  $B_{u,d}\to K\bar{K}$ and $B^\pm\to\pi^\pm K$

abstract:
  In the recent literature, constraints on the CKM angle $\gamma$ arising from
the branching ratios for $B^\pm\to\pi^\pm K$ and $B_d\to\pi^\mp K^\pm$ decays
received a lot of attention. An important theoretical limitation of the
accuracy of these bounds is due to rescattering effects, such as
$B^+\to\{\pi^0K^+\}\to\pi^+K^0$. We point out that these processes are related
to penguin topologies with internal up quark exchanges and derive SU(2) isospin
relations among the $B^+\to\pi^+K^0$ and $B_d^0\to\pi^-K^+$ decay amplitudes by
defining ``tree'' and ``penguin'' amplitudes in a proper way, allowing the
derivation of generalized bounds on the CKM angle $\gamma$. We propose
strategies to obtain insights into the dynamics of penguin processes with the
help of the decays $B_{u,d}\to K\bar{K}$ and $B^\pm\to\pi^\pm K$, derive a
relation among the direct CP-violating asymmetries arising in these modes, and
emphasize that rescattering effects can be included in the generalized bounds
on $\gamma$ completely this way. Moreover, we have a brief look at the impact
of new physics.


title: Coupled Gap Equations for the Screening Masses in Hot SU(N) Gauge Theory

abstract:
  Coupled 1-loop gap equations are studied numerically for non-Abelian electric
and magnetic screening in various versions of the three-dimensional effective
gauge models. Corrections due to higher dimensional and non-local operators are
assessed quantitatively. Comparison with numerical Monte-Carlo investigations
suggests that quantitative understanding beyond the qualitative features can be
achieved only by going beyond the present treatment.


title:
Next-to-Minimal Supersymmetric Standard Model with the Gauge Mediation
  of Supersymmetry Breaking

abstract:
  We study the Next-to-Minimal Supersymmetric Standard Model (NMSSM) as the
simplest candidate solution to the $\mu$-problem in the context of the gauge
mediation of supersymmetry breaking (GMSB). We first review various proposals
to solve the $\mu$-problem in models with the GMSB. We find none of them
entirely satisfactory and point out that many of the scenarios still lack
quantitative studies, and motivate the NMSSM as the simplest possible solution.
We then study the situation in the Minimal Supersymmetric Standard Model (MSSM)
with the GMSB and find that an order 10% cancellation is necessary between the
$\mu$-parameter and the soft SUSY-breaking parameters to correctly reproduce
$M_Z$. Unfortunately, the NMSSM does not to give a phenomenologically viable
solution to the $\mu$-problem. We present quantitative arguments which apply
both for the low-energy and high-energy GMSB and prove that the NMSSM does not
work for either case. Possible modifications to the NMSSM are then discussed.
The NMSSM with additional vector-like quarks works phenomenologically, but
requires an order a few percent cancellation among parameters. We point out
that this cancellation has the same origin as the cancellation required in the
MSSM.


title: Searching for New Physics with CP Violating B Decays

abstract:
  We explore the possibility of using CP violation in B decays to detect the
presence of physics beyond the Standard Model. We first study the possibility
of new physics in the $B-\bar B$ mixing amplitude. We discuss a construction to
extract information about the phase and magnitude of the new physics
contribution, as well as the CKM parameters in a model independent way. We
point out the difficulty of carrying through this program induced by hadronic
uncertainties and discrete ambiguities, and suggest additional measurements to
overcome these problems. We then study the possibility of new physics
contributions to the B meson decay amplitudes. We emphasize the sensitivity of
the $B\to \phi K_S$ decay to these new contributions, and explain how this
sensitivity can be quantified using experimental data on SU(3) related decays.
Finally, we analyse a number of models where the B decay amplitudes are
modified.


title: Beta functions and anomalous dimensions up to three loops

abstract:
  We derive an algorithm for automatic calculation of perturbative
$\beta$-functions and anomalous dimensions in any local quantum field theory
with canonical kinetic terms. The infrared rearrangement is performed by
introducing a common mass parameter in all the propagator denominators. We
provide a set of explicit formulae for all the necessary scalar integrals up to
three loops.


title:
A Simple Model of Gauge Mediated Supersymmetry Breaking with Composite
  Messenger Fields

abstract:
  We present a simple model of gauge mediated supersymmetry breaking with
composite messenger fields. Our model is based on the gauge group $Sp(8) \times
SU(2)$. By the strong Sp(8) dynamics, supersymmetry is dynamically broken and
the composite fields with charges under the standard model gauge group appear
at low energy. The $U(1)_R$ symmetry breaking mass terms for the composite
fields are generated by the strong SU(2) dynamics. Then, the composite fields
play a role of the messenger fields. On the other hand, the theoretical bounds
on the parameters in our model are discussed. Especially, the lower bound on
the dynamical scale of the $Sp(8) \times SU(2)$ gauge interaction is roughly
$10^{15}$ GeV.


title: The Phenomenology of Inclusive Heavy-to-Light Sum Rules

abstract:
  By calculating the O(\alpha_s) corrections to inclusive heavy-to-light sum
rules we find model independent upper and lower bounds on form factors for B to
pi and B to rho. We use the bounds to rule out model predictions. Some models
violate the bounds only for certain ranges of sum rule input parameters
\bar{lambda} \simeq m_B-m_b and lambda_1, or for certain choices of model
parameters, while others obey or violate the bounds irrespective of the inputs.
We discuss the reliability and convergence of the bounds, point out their
utility for extracting V_{ub}, and derive from them a new form factor scaling
relation.


title: Recent progress on HQET lagrangian

abstract:
  HQET lagrangian up to $1/m^3$ terms is discussed. Consequences of
reparameterization invariance are considered. Results for the chromomagnetic
interaction coefficient at two loops, and in all orders in the large--$\beta_1$
approximation, are presented.


title: Low-energy Gravitino Interactions

abstract:
  I discuss the low-energy limit of several processes involving only ordinary
particles and gravitinos. Astrophysical and laboratory applications are briefly
addressed.


title:
Collective mechanism of dilepton production in high-energy nuclear
  collisions

abstract:
  Collective bremsstrahlung of vector meson fields in relativistic nuclear
collisions is studied within the time-dependent Walecka model. Mutual
deceleration of the colliding nuclei is described by introducing the effective
stopping time and average rapidity loss of baryons. It is shown that
electromagnetic decays of virtual omega-mesons produced by bremsstrahlung
mechanism can provide a substantial contribution to the soft dilepton yield at
the SPS bombarding energies. In particular, it may be responsible for the
dilepton enhancement observed in 160 AGev central Pb+Au collisions. Suggestions
for future experiments to estimate the relative contribution of the collective
mechanism are given.


title:
Momentum Spectrum of $\eta'$ Meson in the Inclusive Decay $B\to
  \eta'X_s$

abstract:
  The momentum distribution for the $\eta'$ meson produced through the
inclusive decay $B\to \eta'X$ is investigated under two decay mechanisms,
$b\to\eta's$ and $b\to \eta' s g$. Although all these two mechanisms can
explain the recently observed decay rate of $B\to \eta'X$, the momentum
spectrums for $\eta'$ meson predicted by them are strongly different. Thus
detailed experiment is proposed to distinguish the two cases.


title:
Antihydrogen production and accuracy of the equivalent photon
  approximation

abstract:
  The production of antihydrogen in flight in antiproton-nucleus collisions is
calculated theoretically in the Plane Wave Born Approximation (which is
equivalent to the straight line semiclassical approximation). Antihydrogen has
been produced in this way at LEAR/CERN and is presently studied at FERMILAB at
various antiproton energies. Dirac wave functions for the leptons are used,
taking first order (Z.alpha) corrections into account. Analytical results are
obtained for differential cross-sections. Total cross sections are obtained by
numerical integration. The dependence on the transverse momentum transfer is
studied and the accuracy of the equivalent photon approximation and a recent
variant by Munger, Brodsky,and Schmidt is discussed as a function of beam
energy.


title: Instantons and Single Spin Asymmetries

abstract:
  A new mechanism for single spin asymmetries in strong interaction is
proposed. It is based on instanton-induced nonperturbative chromomagnetic
quark-gluon interaction. We estimate the contribution of this interaction to
single spin asymmetry in quark-quark scattering. It is shown, that interference
between quark spin-flip amplitude induced by instantons and spin-nonflip
amplitude, which is related to nonperturbative two gluon exchange, gives a
large value for a single spin asymmetry. Due to strong increasing of the
instanton-induced spin-flip amplitude with energy, this asymmetry does not
vanish at high energies.


title: Rare decays of \eta-meson: the background of \rho- and \omega- mesons

abstract:
  The problem of $\rho$- and $\omega$- mesons contributions to the background
for $\eta \to \pi^0 e^+e^-$ decay and to the asymmetries in the decays $\eta
\to \pi^+\pi^-\pi^0$ and $\eta \to \pi^+\pi^-\gamma$ is considered.


title:
Charmed sea contribution to the inclusive hadroproduction of the mesons
  with open charm in the Quark -- Gluon String Model

abstract:
  The hadroproduction of charmed mesons is discussed within the framework of
the modified Quark-Gluon String model (QGSM) taking into account the decays of
corresponding $S$--wave resonances like $D^*$. It is shown that the estimate of
the $c\bar{c}$--pair contribution to the quark sea of colliding hadrons
strongly depends on the parametrization of the function of the leading light
quark fragmentation into charmed mesons. A description of the existing
experimental data on inclusive spectra and asymmetries of leading and
nonleading $D$ - and $D^*$ - meson production in $ \pi p$ -, $p p$ - and
$\Sigma p$ - collisions is obtained. The predictions for leading/nonleading
asymmetry in $\Sigma^- p$-- and $\Xi^-p$-- collisions are also given.


title: Conformal bootstrap for the BFKL Pomeron

abstract:
  We calculate the interaction vertex of three BFKL states including the bare
triple BFKL Pomeron coupling and discuss its relation with the correlation
functions in two-dimensional conformal field theory. We construct the operator
algebra of the fields interpolating the BFKL states and show that in the
multi-color limit the vertex satisfies the constraints imposed by the conformal
bootstrap on the structure constants of the operator product expansion in
conformal field theory.


title: The Decays K_L -> l^+ l^- l'^+ l'^- Revisited

abstract:
  The double lepton pair decay modes of the K_L meson are analyzed including
all contributions of order p^6 in Chiral Perturbation Theory. The
experimentally established e^+ e^- e^+ e^- mode and the recently observed e^+
e^- mu^+ mu^- mode are discussed in detail.


title: Precision Tests of the Standard Model

abstract:
  Precision measurements of electroweak observables provide stringent tests of
the Standard Model structure and an accurate determination of its parameters.
An overview of the present experimental status is presented.


title: |Delta F| = 1 Nonleptonic Effective Hamiltonian in a Simpler Scheme

abstract:
  We consider |\Delta F| = 1 (F = S,C or B) nonleptonic effective hamiltonian
in a renormalization scheme which allows to consistently use fully
anticommuting gamma_5 at any number of loops, but at the leading order in the
Fermi coupling G_F. We calculate two-loop anomalous dimensions and one-loop
matching conditions for the effective operators in this scheme. Finally, we
transform our results to one of the previously used renormalization schemes,
and find agreement with the original calculations.


title: Bileptons - Status and Prospects

abstract:
  Theoretical backgound for bileptonic gauge bosons is reviewed, both the
SU(15) GUT model and the 3-3-1 model. Then the mass limits for bileptons are
discussed coming from $e^+e^-$ scattering, polarized muon decay and
muonium-antimuonium conversion. A consequence of precision electroweak data on
the masses is mentioned. Discovery in $e^-e^-$ at a linear collider is
emphasised.


title: S and T for Leptoquarks and Bileptons

abstract:
  We calculate contributions to the oblique parameters $S$ and $T$ for
leptoquarks and bileptons, and find phenomenological constraints on their
allowed masses. Leptoquarks suggested by the neutral and charged current
anomalies at HERA can give improved agreement with both $S$ and $T$. If
bileptons are the only new states, the singly-charged one must be heavier than
the directly-established lower limit. We also consider SU(15) grand unification
to find when it can be consistent with precision electroweak measurements.


title:
susy23 v2.0: an Event Generator for Supersymmetric Processes at $e^+e^-$
  Colliders

abstract:
  \susy23 is a Monte-Carlo package for generating supersymmetric (SUSY)
processes at $e^+e^-$ colliders. Twenty-three types of SUSY processes with 2 or
3 final state particles at tree level are included in version 2.0. {\susy23}
addresses event simulation requirements at $e^+e^-$ colliders such as LEP.
Matrix elements are generated by GRACE with the helicity amplitude method for
processes involving massive fermions. The phase space integration of the matrix
element gives the total and differential cross sections, then unweighted events
are generated. Sparticle widths and decay branching ratios are calculated. Each
final state particle may then decay according to these probabilities. Spin
correlations are taken into account in the decays of sparticles. Corrections of
initial state radiation (ISR) are implemented in two ways, one is based on the
electron structure function formalism and the second uses the parton shower
algorithm called QEDPS. Parton shower and hadronization of the final quarks are
performed through an interface to JETSET.


title:
Large corrections to asymptotic $F_{\eta_c \gamma}$ and $F_{\eta_b
  \gamma}$ in the light-cone perturbative QCD

abstract:
  The large-$Q^2$ behavior of $\eta_c$-$\gamma$ and $\eta_b$-$\gamma$
transition form factors, $F_{\eta_c\gamma}(Q^2)$ and $F_{\eta_b\gamma}(Q^2)$
are analyzed in the framework of light-cone perturbative QCD with the heavy
quark ($c$ and $b$) mass effect, the parton's transverse momentum dependence
and the higher helicity components in the light-cone wave function are
respected. It is pointed out that the quark mass effect brings significant
modifications to the asymptotic predictions of the transition form factors in a
rather broad energy region, and this modification is much severer for
$F_{\eta_b\gamma}(Q^2)$ than that for $F_{\eta_c\gamma}(Q^2)$ due to the
$b$-quark being heavier than the $c$-quark. The parton's transverse momentum
and the higher helicity components are another two factors which decrease the
perturbative predictions. For the transition form factor
$F_{\eta_c\gamma}(Q^2)$, they bring sizable corrections in the present
experimentally accessible energy region ($Q^2 \leq 10 GeV^2$). For the
transition form factor $F_{\eta_b\gamma}(Q^2)$, the corrections coming from
these two factors are negligible since the $b$-quark mass is much larger than
the parton's average transverse momentum. The coming $e^+ e^-$ collider (LEP2)
will provide the opportunity to examine these theoretical predictions.


title:
Strangeness production in nuclear interactions at 200 AGeV and the
  number of nucleon-nucleon collisions

abstract:
  Data on mean numbers of $\Lambda$, $\bar\Lambda$, K's and on the total number
$<s\bar s>$ of pairs of strange valence quarks in final state hadrons in
hadronic and nuclear collisions at CERN- SPS energies are studied as a function
of the mean number $<n_{coll}>$ of nucleon- nucleon collisions. Results give
indications of an almost linear dependence over most of the region of
$<n_{coll}>$. This in turn points out to strangeness being produced mostly in
the central rapidity region of nucleon- nucleon collisions by a mechanism
similar to a hard or semi- hard process. The available data are extrapolated to
Pb+Pb interactions by two simple models, leading to $<s\bar s>_{Pb+Pb}\approx
300\pm 30 $.
  Observations exceeding these values of $<s\bar s>_{Pb+Pb}$ would give
evidence of the onset of a new dynamical regime in Pb+Pb interactions.


title: The Higgs boson mass bound in MSSM broken at high scale

abstract:
  We study the dependence of the Higgs boson mass on the supersymmetry breaking
scale in the minimal supersymmetric extension of the standard Weinberg-Salam
model. In particular, we find that for supersymmetry breaking scale $10^8$ GeV
$\leq M_s \leq 10^{16}$ GeV and for $m^{pole}_{top} = 175 \pm 5 $ GeV the Higgs
boson mass is 120 GeV $ \leq m_h \leq 160 $ GeV


title: Calculation of Quarkonium Spectrum and $m_b, m_c$ to Order $\alpha_s^4$

abstract:
  We include two loop, relativistic one loop and second order relativistic tree
level corrections, plus leading nonperturbative contributions, to obtain a
calculation of the lower states in the heavy quarkonium spectrum correct up to,
and including, $O(\alpha_s^4)$ and leading $\Lambda^4/m^4$ terms. This allows
us, in particular, to obtain a model independent determination of the pole
masses of the $b, c$ quarks, $$m_b=5 015^{+110}_{-70} mev; m_c=1
884^{+222}_{-133} mev$$ to which correspond the $\bar{\hbox{MS}}$ masses,
$$\bar{m}_b(\bar{m}_b^2)=4 453^{+50}_{-32} mev; \bar{m}_c(\bar{m}_c^2)=1
547^{+169}_{-102} mev.$$ The decay $\Gamma(\Upsilon\to e^+e^-)$ is found in
agreement with experiment, $$\Gamma(\Upsilon\to e^+e^-)=1.135^{+0.27}_{-0.29}
kev (\hbox{exp.}=1.320\pm0.04 kev),$$ and the hyperfine splitting is predicted
to be $$M(\Upsilon)-M(\eta)=48.5^{+15.7}_{-12.2} mev.$$


title: Minimal Supersymmetric $SU(4) \times SU(2)_L \times SU(2)_R$

abstract:
  We present a minimal string-inspired supersymmetric $SU(4) \times SU(2)_L
\times SU(2)_R$ model, and provide a detailed analysis of the symmetry breaking
potential in this model, based on a generalisation of that recently proposed by
Dvali, Lazarides and Shafi. The model contains a global U(1) R-symmetry and
reduces to the MSSM at low energies. However it improves on the MSSM since it
explains the magnitude of its $\mu$ term and gives a prediction for $\tan \beta
\simeq m_t/m_b$. It also predicts an essentially stable proton, and contains
both `cold' and `hot' dark matter candidates. A period of hybrid inflation
above the symmetry breaking scale is also possible in this model. Finally it
suggests the existence of `heavy' charge $\pm e/6$ (colored) and $\pm e/2$
(color singlet) states.


title:
Colour Deconfinement and J/Psi Suppression in High Energy Nuclear
  Collisions

abstract:
  1. Introduction 2. Charmomium Dissociation and Colour Deconfinement 3. J/Psi
Production in Nuclear Collisions 4. Anomalous J/Psi Suppression 5. Outlook and
Summary


title: Double Spin Asymmetries in Charmonium Hadroproduction at HERA-$\vec N$

abstract:
  We discuss the double spin asymmetries in charmonium hadroproduction with
nonzero transverse momenta at fixed target energies, $\sqrt{s}\simeq40$ GeV,
within the framework of the factorization approach. It is shown that the color
octet contribution is dominant in the asymmetries. The size of the asymmetries
and the projected statistical errors in a future option of HERA with
longitudinally polarized protons scattering off a polarized target (HERA-$\vec
N$) should allow to distinguish between different parametrizations for the
polarized gluon distribution in the proton.


title: Low x Inelastic Electron Scattering From Generalized Vector Dominance

abstract:
  It is shown that the HERA experimental data on deep inelastic scattering at
low values of the scaling variable x < 0.05 are in good agreement with
predictions from Generalized Vector Dominance in the full kinematic range from
Q2 = 0 (photoproduction) to Q2 = 350 GeV.


title: The Lamb Shift in Dimensional Regularization

abstract:
  We present a simple derivation of the Lamb shift using effective field theory
techniques and dimensional regularisation.


title:
New Constraint on the Parameters in Cabibbo-Kobayashi-Maskawa Matrix of
  Wolfenstein's Parametrization

abstract:
  Based on the relation between CP-violation phase and the other three mixing
angles in Cabibbo-Kobayashi-Maskawa matrix postulated by us before, a new
constraint on the parameters of Wolfenstein's parametrization is given. The
result is consistent with the relative experimental results and can be further
put to the more precise tests in future.


title: Natural Neutrino Mass Matrix

abstract:
  Naturalness of the neutrino mass hierarchy and mixing is studied. First we
select among 12 neutrino mixing patterns a few patterns, which could form the
natural neutrino mass matrix. Further we show that if the Dirac neutrino mass
matrix is taken as the natural one in the quark sector, then only two mixing
patterns without the large mixing lead to the natural right-handed Majorana
mass matrix. The rest of the chosen patterns with three degenerate mass
solution lead to the unnatural right-handed Majorana mass matrix in the see-saw
mechanism. Notice however, that for the chosen two natural patterns there could
be a huge mass hierarchy such as ${\cal O}(10^{4\sim 6})$ in order to reproduce
the inverse mass hierarchy of the light neutrinos.


title: Baryon Spectra in Deformed Oscillator Quark Model

abstract:
  We study theoretically the baryon spectra in terms of a deformed oscillator
quark (DOQ) model. This model is motivated by confinement of quarks and chiral
symmetry breaking, which are the most important non-perturbative phenomena of
QCD. The minimization of the DOQ hamiltonian with respect to the deformation
for each principal quantum number results in deformations for the intrinsic
states of excited baryonic states. We find that the resulting baryon spectra
agree very well with the existing experimental data. The spatial deformation of
the baryonic excited states carry useful information on the quark confinement
and provide a clue to understand the confining mechanism.


title: 1/N_c Expansion of the Heavy Baryon Isgur-Wise Functions

abstract:
  The 1/N_c expansion of the heavy baryon Isgur-Wise functions is discussed.
Because of the contracted SU(2N_f) light quark spin-flavor symmetry, the
universality relations among the Isgur-Wise functions of \Lambda_b to \Lambda_c
and \Sigma_b^{(*)} to \Sigma_c^{(*)} are valid up to the order of 1/N_c^2.


title: QCD sum rules at finite temperature

abstract:
  We derive thermal QCD sum rules for the correlation function of two vector
currents in the rho-meson channel. It takes into account the leading
non-perturbative corrections from the additional operators, which appear due to
the breakdown of Lorentz invariance at finite temperature. The mixing of the
new operators has a drastic effect on their coefficients. The thermal average
of all the operators can be related to that of the quark condensate and the
energy density. The sum rules then yield the temperature dependence of the
parameters of the $\rho$-meson, namely its mass and coupling to the vector
current. Our result is that these parameters are practically independent of
temperature at least up to a temperature of 125 MeV.


title: Sum rule for the twist four longitudinal structure function

abstract:
  We investigate the twist four longitudinal structure function
$F_{L}^{\tau=4}$ of deep inelastic scattering and show that the integral of
${F_{L}^{\tau=4} \over x}$ is related to the expectation value of the fermionic
part of the light-front Hamiltonian density at fixed momentum transfer. We show
that the new relation, in addition to providing physical intuition on
$F_{L}^{\tau=4}$, relates the quadratic divergences of $F_{L}^{\tau=4}$ to the
quark mass correction in light-front QCD and hence provides a new pathway for
the renormalization of the corresponding twist four operator. The mixing of
quark and gluon operators in QCD naturally leads to a twist four longitudinal
gluon structure function and to a new sum rule $ \int dx {F_L \over x}= 4 {M^2
\over Q^2}$, which is the first sum rule obtained for a twist four observable.
The validity of the sum rule in a non-perturbative context is explicitly
verified in two-dimensional QCD.


title: What lattice calculations tell us about the glueball spectrum

abstract:
  I review what lattice QCD simulations have to tell us about the glueball
spectrum. Talk given at HEP97, Jerusalem, August 1997.


title:
Dynamical Chiral Symmetry Breaking from Variationally Improved
  Perturbative Expansion

abstract:
  We review how a specific resummation of the so-called "delta-expansion",
applied to the QCD Lagrangian, transforms the ordinary perturbative expansion
in $\alpha_s$ into an expansion in an arbitrary mass parameter, around the
basic scale $\bar\Lambda$. When applied to the pole mass, the resulting
expression may be interpreted as a dynamical mass ansatz, to be optimized with
respect to the new expansion (mass) parameter. The construction is generalized
to obtain estimates of the order parameters of the $SU(n_f)_L \times SU(n_f)_R$
($n_f =2,3$) symmetry breakdown.


title: CP Violation in Selected B Decays

abstract:
  We summarize the results of two papers in which we have studied CP violation
in inclusive and exclusive decays b -> d e^+e^-. Two CP-violating effects are
calculated: the partial rate asymmetry between b and \bar{b} decay, and the
asymmetry between e^- and e^+ spectra for an untagged B/\bar{B} mixture. These
asymmetries, combined with the branching ratio, can potentially determine the
parameters (\rho, \eta) of the unitarity triangle. We also summarize a paper by
Browder et al. on a possible CP-violating asymmetry in the inclusive reaction B
-> K^-(K^{*-})X.


title:
Radiative Corrections to W^+W^- \to W^+W^- in the Electroweak Standard
  Model

abstract:
  The cross-section for W^+W^- \to W^+W^- with arbitrarily polarized W bosons
is calculated within the Electroweak Standard Model including the complete
virtual and soft-photonic O(alpha) corrections. We show the numerical
importance of the radiative corrections for the dominating polarized
cross-sections and for the unpolarized cross-section. The numerical accuracy of
the equivalence theorem is investigated in O(alpha) by comparing the
cross-section for purely longitudinal W bosons obtained from the equivalence
theorem and from the direct calculation. We point out that the instability of
the W boson, which is inherent in the one-loop corrections, prevents a
consistent calculation of radiative corrections to the scattering of
on-real-mass-shell longitudinal W bosons beyond O(alpha).


title: Final State Interactions in WW Production

abstract:
  It is shown that colour transparency causes nonperturbative colour-singlet
final-state interactions to have a negligible effect on the production rate and
the dijet mass spectra in $e^+e^-\to WW$. However, the same cannot be said of
nonperturbative colour-octet exchange, for which we show that there are
indications of observable effects, though we are unable to present precise
estimates.


title: Measurement of the W Boson Mass at the LHC

abstract:
  We explore the ability of the Large Hadron Collider to measure the mass of
the W boson. We believe that a precision better than 15 MeV could be attained,
based on a year of operation at low luminosity (10^{33} cm^-2 s^-1). If this is
true, this measurement will be the world's best determination of the W mass


title: The Z Boson Resonance and Radiative Corrections

abstract:
  The Z line shape is measured at LEP 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 different
model-independent approaches in order to extract quantities like mass and width
of the Z boson. If a fit deviates from that in the standard approach, this may
give hints for New Physics contributions. I describe two model-independent
approaches and compare their applications to LEP data with the Standard Model
approach.


title: Limits on Neutrino Masses in SO(10) GUT's

abstract:
  Studying Renormalization Group Equations for the four typical SO(10)
spontaneous symmetry breaking patterns we find the existence of lower limits on
neutrino masses.


title:
Radiative Corrections to Chargino Production in Electron-Positron
  Collisions

abstract:
  We discuss the one-loop radiative corrections to the reaction e^+ e^- ->
X^+_a X^-_b, for a,b=1,2 where X^+_{1,2} are the charginos of the minimal
supersymmetric standard model. We calculate the leading one loop radiative
corrections involving loops of top, stop, bottom and sbottom quarks, working in
the MS-bar scheme. At LEP2 we find positive radiative corrections typically of
10% to 15% and with a maximum value of approximately 30% if the squark mass
parameters are of the order of 1 TeV. If \sqrt{s}=500 GeV we find smaller
corrections but they can be also negative, with extreme values of 13% and -4%.
For a center of mass given by \sqrt{s}=2 TeV we find larger corrections, with
typical values between 20% and -20%.


title:
Improved Determination of alpha_QED(M_Z^2) and the Anomalous Magnetic
  Moment of the Muon

abstract:
  We reevaluate the hadronic contribution to the running of the QED fine
structure constant alpha(s) at s = M_Z^2. We use data from e+e- annihilation
and tau decays at low energy and at the qq-bar thresholds, where resonances
occur. Using so-called spectral moments and the Operator Product Expansion
(OPE), it is shown that a reliable theoretical prediction of the hadronic
production rate R(s) is available at relatively low energies. Its application
improves significantly the precision on the hadronic vacuum polarization
contribution. We obtain delta_alpha^had = (277.8 +/- 2.6) x 10^-4 yielding
alpha^-1(M_Z^2) = 128.923 +/- 0.036$. Inserting this value in a global
electroweak fit using current experimental input, we constrain the mass of the
Standard Model Higgs boson to be M_Higgs = (129 +103 -62) GeV. Analogously, we
improve the precision of the hadronic contribution to the anomalous magnetic
moment of the muon for which we obtain a_mu^had = (695.1 +/- 7.5) x 10^-10.


title:
Virtual Next-to-Leading Corrections to the Impact Factors in the
  High-Energy Limit

abstract:
  We compute the virtual next-to-leading corrections to the impact factors or
off-shell coefficient functions in the high-energy limit. When combined with
the known real corrections, these results will provide the complete NLO
corrections to the impact factors, which are necessary to use the BFKL
resummation at NLL for jet production at both lepton-hadron and hadron-hadron
colliders.