title: Physical origin of "chaoticity" of neutrino asymmetry

abstract:
  We consider the indeterminacy in the sign of the neutrino asymmetry generated
by active-sterile neutrino oscillations in the early universe. The dynamics of
asymmetry growth is discussed in detail and the indeterminacy in the final sign
of the asymmetry is shown to be a real physical phenomenon. Recently published
contradicting results are carefully considered and the underlying assumptions
leading to the disagreement are resolved.


title: KLN theorem, magnetic mass, and thermal photon production

abstract:
  We study the infrared singularities associated to ultra-soft transverse
gluons in the calculation of photon production by a quark-gluon plasma. Despite
the fact that the KLN theorem works in this context and provides cancellations
of infrared singularities, it does not prevent the production rate of low
invariant mass dileptons to be sensitive to the magnetic mass of gluons and
therefore the rate to be non perturbative.


title: QCD Processes at the Amplitude Level

abstract:
  Some of the most difficult theoretical challenges of QCD occur at the
interface of the perturbative and nonperturbative regimes. Exclusive and
semi-exclusive processes, the diffractive dissociation of hadrons into jets,
and hard diffractive processes such as vector meson leptoproduction provide new
testing grounds for QCD and essential information on the structure of
light-cone wavefunctions of hadrons, particularly the pion distribution
amplitude. I review the basic features of the leading-twist QCD predictions and
the problems and challenges of studying QCD at the amplitude level.


title: Strong phases and D0-anti-D0 mixing parameters

abstract:
  We argue that there could be large, SU(3) violating resonance contributions
to D -> K pi decays which would affect the extraction of the D0-anti-D0 mixing
parameters from experiment. Such contributions can induce a large strong phase
in the interference between the doubly Cabibbo suppressed and the mixing
induced Cabibbo favored contributions to the D0 -> K^+ pi^- and anti-D0 -> K^-
pi^+ decays. Consequently, the interpretation of a large, CP conserving
interference term can involve a large mass difference Delta M rather than a
large width difference Delta Gamma.


title:
Neutrino Parameters, Abelian Flavor Symmetries, and Charged Lepton
  Flavor Violation

abstract:
  Neutrino masses and mixings have important implications for models of fermion
masses, and, most directly, for the charged lepton sector. We consider
supersymmetric Abelian flavor models, where neutrino mass parameters are
related to those of charged leptons and sleptons. We show that processes such
as \tau to \mu\gamma, \mu to e\gamma and \mu-e conversion provide interesting
probes. In particular, some existing models are excluded by current bounds,
while many others predict rates within reach of proposed near future
experiments. We also construct models in which the predicted rates for charged
lepton flavor violation are below even the proposed experimental sensitivities,
but argue that such models necessarily involve loss of predictive power.


title: Classical methods in DIS and nuclear scattering at small x

abstract:
  In hadrons and nuclei at very small x, parton distributions saturate at a
scale Q_s(x). Since the occupation number is large, and
$Q_s(x)>>\Lambda_{QCD}$, classical weak coupling methods may be used to study
this novel regime of non-linear classical fields in QCD. In these lectures, we
apply these methods to compute structure functions in deeply inelastic
scattering (DIS) and the energy density of gluons produced in high energy
nuclear collisions.


title:
Bounds on universal new physics effects from fermion-antifermion
  production at LEP2

abstract:
  We consider lepton-antilepton annihilation into a fermion-antifermion pair at
variable c.m. energy. We propose for this process a simple parametrization of
the virtual effects of the most general model of new physics of
\underline{universal} type. This parametrization is based on a recent approach,
that uses the experimental results of LEP1, SLC as theoretical input. It
introduces \underline{three} functions whose energy dependence is argued to be
smooth and, in first approximation, negligible. A couple of representative
models of new physics are considered, as a support of the previous claim.
Explicit bounds are then derived for this type of new physics from the
available LEP2 data, and a discussion is given of the relevance in this respect
of the different experimental measurements. The method is then extended to
treat the case of two particularly simple models of {\it non universal} type,
for which it is possible to draw analogous conclusions.


title: Is the riddle of the hyperon polarizations solved?

abstract:
  We review in this talk some aspects of the exciting field of hyperon
polarization phenomena in high energy reactions, over the last twenty years or
so. On the experimental side, a large amount of significant polarization data
for hyperon and antihyperon inclusive production, has been accumulated in a
rather broad energy range. Many theoretical attempts to explain that have been
proposed and we will discuss some of them, showing their strong limitations in
most cases.


title: Dynamical resummation and damping in the O(N) model

abstract:
  A general real-time formalism is developed to resum the self-energy operator
of broken symmetry scalar field theories in form of self-consistent gap
equations for the spectral function. The solution of the equations is
approximated with finite lifetime quasi-particles. In the Landau damping rates
viscosity terms, analogous to gauge theories, appear, what leads to a finite
damping rate for the long wavelength Goldstone modes.


title: The physics of exclusive reactions in QCD: Theory and phenomenology

abstract:
  The modern formulation of exclusive reactions within Quantum Chromodynamics
is reviewed, the emphasis being placed on the pivotal ideas and methods
pertaining to perturbative and non-perturbative topics. Specific problems,
related to scale locality, infrared safety, gluonic radiative corrections
(Sudakov effects), and the role of hadronic size effects (intrinsic transverse
momentum), are studied. These issues are more precisely analyzed in terms of
the essential mechanisms of momentum transfer to a hadron while remaining
intact. Different factorization schemes are considered and the conceptual
lacunas are pointed out. The quite technical subject of renormalization-group
evolution is given a detailed account. By combining analytical and numerical
algorithms, the one-gluon exchange nucleon evolution equation is diagonalized
and next-to-leading eigenfunctions are calculated in terms of Appell
polynomials. The corresponding anomalous dimensions of trilinear quark
operators are found to form a degenerate system whose envelope shows
logarithmic large-order behavior. Selected applications of this framework are
presented, focusing on the helicity-conserving elastic form factors of the pion
and the nucleon. The theoretical constraints imposed by QCD sum rules on the
moments of nucleon distribution amplitudes are used to determine a whole
spectrum of optional solutions. They organize themselves along an ``orbit''
characterized by a striking scaling relation between the form-factor ratio
$R=|G_{\rm M}^{\rm n}|/G_{\rm M}^{\rm p}$ and the projection coefficient
$B_{4}$ on to the corresponding eigensolution. The main reasons for the failure
of the present theoretical predictions to match the experimental data are
discussed and workable explanations are sketched.


title: Nonperturbative dispersive sector in strong (quasi-)Abelian fields

abstract:
  In strong (quasi-)Abelian fields, even at the one-loop level of the coupling
constant, quantum fluctuations of fermions induce an effective Lagrangian
density whose imaginary (absorptive) part is purely nonperturbative and known
to be responsible for the fermion-antifermion pair creation. On the other hand,
the induced real (dispersive) part has perturbative and nonperturbative
contributions. In the one-loop case, we argue how to separate the two
contributions from each other for any strength of the field. We show
numerically that the nonperturbative contributions are in general comparable
with or larger than the induced perturbative ones. We arrive at qualitatively
similar conclusions also for the induced energy density. Further, we
investigate numerically the quasianalytic continuation of the perturbative
results into the nonperturbative sector, by employing (modified) Borel-Pade. It
turns out that in the case at hand, we have to integrate over renormalon
singularities, but there is no renormalon ambiguity involved.


title:
Space-like meson electromagnetic form factor in a relativistic quark
  model

abstract:
  The space-like electromagnetic form factor is expressed in terms of the
overlap integral of the initial and final meson wave functions written as
Lorentz covariant distributions of internal momenta. The meson constituents are
assumed to be valence quarks and an effective vacuum-like field. The momentum
of the latter represents a relativistic generalization of the potential energy
of the quark system. The calculation is fully Lorentz covariant and the form
factors of the charged mesons are normalized to unity at t=0. The numerical
results have been obtained by freezing the transverse degrees of freedom. We
found r_\pi^2=0.434 fm^2, r_{K^+}^2=0.333 fm^2, r_{K^0}^2=-0.069 fm^2 by taking
m_{u,d}=430 MeV, m_s=700 MeV.


title: Klein-Fock equation, proper-time formalism and symmetry of Hydrogen atom

abstract:
  We present main points of some of Fock papers in Quantum Theory, which were
not properly followed when published.


title: Unintegrated parton distributions and prompt photon hadroproduction

abstract:
  We introduce a general expression which enables the parton distribution,
unintegrated over the parton transverse momentum, to be obtained from the
conventional parton densities. We use the formalism to study the effects of the
transverse momentum q_t of the incoming partonic system on the calculation of
the transverse momentum spectra of prompt photons produced in high energy pp
and p\bar{p} collisions. For the purposes of illustration, we use the double
logarithm approximation. For large q_t we calculate the effect directly from
the perturbative formalism, whereas for small q_t we bound the effect using two
extreme hypotheses. In both q_t domains we find that the shapes of the prompt
photon spectra are not significantly modified, although the cross sections are
enhanced.


title: Weakly First Order Cosmological Phase Transitions and Fermion Production

abstract:
  We study weakly first order cosmological phase transitions in finite
temperature field theories. Focusing on the standard electroweak theory and its
minimal supersymmetric extension, we identify the regimes of Higgs masses for
which the phase transition in these models proceeds by significant phase mixing
and the coarsening of the subsequent domain network. This dynamics is distinct
from that for strongly first order transitions, which proceed by the nucleation
and propagation of critical bubbles. We describe how electroweak baryogenesis
might take place in these models, explaining how our new picture can relax the
sphaleron washout bound of traditional scenarios.


title:
Hard exclusive electroproduction of decuplet baryons in the large N_c
  limit

abstract:
  The cross sections and transverse spin asymmetries in the hard exclusive
electroproduction of decuplet baryons are calculated in the large N_c limit and
found to be comparable to that of octet baryons. Large N_c selection rules for
the production amplitudes are derived, leading to new sensitive tests of the
spin aspects of the QCD chiral dynamics both in the nonstrange and strange
sectors. Importance of such studies for the reliable extraction of the pion
form factor from pion electroproduction is explained.


title: KAON 99 - Summary and Perspective

abstract:
  An overview of KAON 99 with commentary is presented. Emphasis is placed on
the state of CKM mixing and CP violation. The Jarlskog invariant, J_{CP}, is
shown to provide a useful quantitative comparison of K and B phenomenology. The
potential of future rare and ``forbidden'' decay experiments to probe O(3000
TeV) ``New Physics'' is also described.


title: Extended non-chiral quark models confronting QCD

abstract:
  We discuss the low energy effective action of QCD in the quark sector. When
it is built at the CSB (chiral symmetry breaking) scale by means of
perturbation theory it has the structure of a generalized Nambu-Jona-Lasinio
(NJL) model with CSB due to attractive forces in the scalar channel. We show
that if the lowest scalar meson state is sufficiently lighter than the heavy
pseudoscalar $\pi'$ then QCD favors a low-energy effective theory in which
higher dimensional operators (of the Nambu-Jona-Lasinio type) are dominated and
relatively strong. A light scalar quarkonium ($m_\sigma = 500 \div 600$ MeV)
would provide an evidence in favor to this NJL mechanism. Thus the non-chiral
Quasilocal Quark Models (QQM) in the dynamical symmetry-breaking regime are
considered as approximants for low-energy action of QCD. In the mean-field
(large-N_c) approach the equation on critical coupling surface is derived. The
mass spectrum of scalar and pseudoscalar excited states is calculated in
leading-log approach which is compatible with the truncation of the QCD
effective action with few higher-dimensional operators. The matching to QCD
based on the Chiral Symmetry Restoration sum rules is performed and it helps to
select out the relevant pattern of CSB as well as to enhance considerably the
predictability of this approach.


title: The Paradox of Charmonium Production

abstract:
  The CDF preliminary analysis on polarized charmonium production at moderate
transverse momentum, $p_T \sim 4 - 20$ GeV, severely challenges the color octet
model (COM), which predicts quarkonium to be transversely polarized with
increasing $p_T$. Based on this data, we analyze the compatibility of the
Tevatron and the photoproduction at HERA in the context of the COM. Due to the
uncertainty on the extraction of non-relativistic QCD (NRQCD) matrix elements
and a lack of complete next-to-leading order calculations, one cannot
completely rule out the COM. Nonetheless, both collider experiments seem to
push the input matrix elements to opposite directions, and the puzzle of
quarkonium polarization remains unsolved.


title: A method for identifying H -> tau tau -> e mu pTmiss at the CERN LHC

abstract:
  Weak boson fusion promises to be a copious source of intermediate mass Higgs
bosons at the LHC. The additional very energetic forward jets in these events
provide for powerful background suppression tools. We analyze the subsequent H
-> tau tau -> e mu pTmiss decay for Higgs boson masses in the 100-150 GeV
range. A parton level analysis of the dominant backgrounds demonstrates that
this channel allows the observation of H -> tau tau in a low-background
environment, yielding a significant Higgs boson signal with an integrated
luminosity of order 60 fb^-1 or less, over most of the mass range. We also
restate a No-Lose Theorem for observation of at least one of the CP-even
neutral Higgs bosons in the MSSM, which requires an integrated luminosity of
only 40 fb^-1.


title: Manyfold Universe

abstract:
  We propose that our world is a brane folded many times inside the
sub-millimeter extra dimensions. The folding produces many connected parallel
branes or folds with identical microphysics - a Manyfold. Nearby matter on
other folds can be detected gravitationally as dark matter since the light it
emits takes a long time to reach us traveling around the fold. Hence dark
matter is microphysically identical to ordinary matter; it can dissipate and
clump possibly forming dark replicas of ordinary stars which are good MACHO
candidates. Its dissipation may lead to far more frequent occurrence of
gravitational collapse and consequently to a significant enhancement in
gravitational wave signals detectable by LIGO and LISA. Sterile neutrinos find
a natural home on the other folds. Since the folded brane is not a BPS state,
it gives a new geometric means for supersymmetry breaking in our world. It may
also offer novel approach for the resolution of the cosmological horizon
problem, although it still requires additional dynamics to solve the flatness
problem. Although there are constraints from BBN, structure formation, the
enormity of galactic halos and the absence of stars and globular clusters with
a discernible dark matter component, we show that the model is consistent with
current observational limits. It presents us with a new dark matter particle
and a new framework for the evolution of structure in our universe.


title: Light Scalar Mesons

abstract:
  We review how a certain effective chiral Lagrangian approach to pi pi
scattering, pi K scattering and eta-prime decay to eta pi pi provides evidence
for the existence of light scalars sigma(550) and kappa(900) as well as
describing the f0(980) and the a0(980). An attempt to fit these into a nonet
suggests that their structure is closer to a dual quark-dual antiquark than to
a quark-antiquark. A possible mechanism to explain the next higher mass scalar
nonet is also proposed.


title: Implications of LEP/SLD Data for New Physics in Zbb_bar Couplings

abstract:
  The combined LEP/SLD data on the b\bar b forward-backward asymmetry from the
Z-pole measurements may imply the presence of new physics in the $Zb\bar b$
couplings. In general, the effect of new physics can be parameterized by
$SU_C(3)\times SU_L(2)\times U_Y(1)$ invariant higher dimensional operators. By
fitting the recently announced LEP/SLD data on A_b and R_b, the size of the
coupling strengths of these operators can be determined. We also found that the
new physics operators can be divided into two types, depending on their Higgs
field content. The ones involving the Higgs have very mild effects at higher
energy colliders, while the other type which do not contain the Higgs field can
show significantly large effects on $b\bar b$ production at LEP II, $t\bar t$
production at the NLC and single top production at the Tevatron. The
preliminary data from the LEP II measurements disfavors the second type of
operators.


title: FCNC transition $c\to u\gamma$ in $B_c\to B_u^*\gamma$ decay

abstract:
  We propose the $B_c\to B_u^*\gamma$ decay as the most suitable probe for the
flavour changing neutral transition $c\to u\gamma$. We estimate the short and
long distance contributions to this decay within the standard model and we find
them to be comparable; this is in contrast to radiative decays of $D$ mesons,
that are completely dominated by the long distance contributions. Since the
$c\to u\gamma$ transition is very sensitive to the physics beyond the standard
model, the standard model prediction $Br(B_c\to B_u^*\gamma)\sim 10^{-8}$
obtained here opens a new window for future experiments. The detection of
$B_c\to B_u^*\gamma$ decay at branching ratio well above $10^{-8}$ would signal
new physics.


title: Theoretical status of epsilon'/epsilon

abstract:
  The present theoretical status of the parameter for direct CP violation
epsilon'/epsilon in the Standard Model is reviewed and compared with most
recent experimental measurements of the same quantity. After collecting the
basic expressions for epsilon'/epsilon, the situation of hadronic matrix
element calculations is summarised. The matrix elements constitute the dominant
source of uncertainty for theoretical determinations of epsilon'/epsilon. For
central values of the input parameters, the numerical analysis then yields
results which are generally below the experimental data. Possible reasons for
these findings are discussed.


title: Power corrections to the differential Drell-Yan cross section

abstract:
  We estimate the power corrections (infrared renormalon contributions) to the
coefficient functions for the differential Drell-Yan cross-section
$d^2\sigma/dQ^2dy$, where $Q^2$ is the mass squared and $y$ the rapidity of the
produced lepton pair. We employ the dispersive method based on the analysis of
one-loop Feynman graphs containing a massive gluon.


title: Scheme Dependence of Weak Matrix Elements in the $1/N_c$ Expansion

abstract:
  We show how the scheme- and scale-dependence of the short-distance operator
product expansion with four-quark operators can be correctly accounted for in
the framework of the $1/N_c$-expansion once the hadronization of two-quark
currents has been fixed. We show formulas explicitly in the case of the
$B_K$-parameter. We then use them with our earlier estimates of the
long-distance effects. We compare Chiral Perturbation Theory at Leading- and
Next-to-Leading-Order with the ENJL model results in the chiral limit. Good
matching between the long- and short-distance regimes is obtained and our final
value for the physical scheme independent $\hat B_K$ is $0.77\pm0.05\pm0.05$.


title:
$O(\alpha_s)$ corrections to the correlator of finite mass baryon
  currents

abstract:
  We present analytical next-to-leading order results for the correlator of
baryonic currents at the three loop level with one finite mass quark. We obtain
the massless and the HQET limit of the correlator from the general formula as
particular cases. We also give explicit expressions for the moments of the
spectral density.


title:
Pion production in proton collisions with light nuclei: implications for
  atmospheric neutrinos

abstract:
  Differences among calculations of the atmospheric neutrino beam can be traced
in large part to differences in the representation of pion production by
protons interacting with nuclei in the atmosphere. In this paper we review the
existing data with the goal of determining the regions of phase space in which
new measurements could help to improve the input to the calculations.


title:
Type II Seesaw and a Gauge Model for the Bimaximal Mixing Explanation of
  Neutrino Puzzles

abstract:
  We present a gauge model for the bimaximal mixing pattern among the neutrinos
that explains both the atmospheric and solar neutrino data via large angle
vacuum oscillation among the three known neutrinos. The model does not include
righthanded neutrinos but additional Higgs triplets which acquire naturally
small vev's due to the type II seesaw mechanism. A combination of global
$L_e-L_{\mu}-L_{\tau}$ and $S_3$ symmetries constrain the mass matrix for both
charged leptons and neutrinos in such a way that the bimaximal pattern emerges
naturally at the tree level and needed splittings among neutrinos at the one
loop level. This model predicts observable branching ratios for $\tau\to \mu
\mu\mu$, which could be used to test it.


title: Determining |V_{ub}| from the sum rule for semileptonic B decay

abstract:
  A precise determination of |V_{ub}| can be obtained exploiting the sum rule
for inclusive charmless semileptonic B-meson decays. The sum rule is derived on
the basis of light-cone expansion and b-flavored quantum number conservation.
The sum rule does not receive any perturbative QCD correction. In this
determination of |V_{ub}|, there is no perturbative QCD uncertainty, while the
dominant hadronic uncertainty is avoided. Moreover, this method is not only
theoretically quite clean, but experimentally also very efficient in the
discrimination between B\to X_u\ell\nu signal and B\to X_c\ell\nu background.
The sum rule requires measuring the lepton pair spectrum. We analyze the lepton
pair spectrum, including the leading perturbative and nonperturbative QCD
corrections.


title: About virtual pi --> K Meson Oscillations

abstract:
  In the framework of the Standard Model the probability (and time) of pi --> K
transitions (oscillations) are computed. These transitions are virtual ones
since masses of pi and K mesons differ considerably. These transitions
(oscillations) can be registered through K decays after transitions of virtual
K mesons to their own mass shell by using their quasielastic strong
interactions. But for avoiding the background from inelastic K mesons, the
energies E(pi) of pi mesons must be less than the threshold energy of their
creation, i.e. E(pi) < 0.91GeV. The optimal distances for observation of these
oscillations are computed. Solution of the problem of origin of mixing angle in
the theory of vacuum oscillation is given.


title: Gluon Condensate and Non-Perturbative Quark-Photon Vertex

abstract:
  We evaluate the quark-photon vertex non-perturbatively taking into account
the gluon condensate at finite temperature. This vertex is related to the
previously derived effective quark propagator by a QED like Ward-Takahashi
identity. The importance of the effective vertex for the dilepton production
rate from a quark-gluon plasma is stressed.


title: Quark mixing: determination of top couplings

abstract:
  The top flavour-changing neutral couplings can be large in extended models
with vector-like quarks. In the next decade(s) the CERN Large Hadron Collider
will allow to measure (bound) them with a precision of few per cent.


title: Lattice Gauge Theory

abstract:
  The status of lattice calculations in Quantum Field Theory is reviewed. A
major part is devoted to recent progress in formulating exact chiral symmetry
on the lattice. Another topic which has received a lot of attention is the
influence of dynamical quark effects. Attempts to quantify these effects for
the light hadron spectrum and flavour singlet amplitudes are discussed, as well
as other expected qualitative features of simulations with dynamical quarks.
The remaining parts of the review include recent results for the light quark
masses using non-perturbative renormalisation and the spectrum of glueballs and
heavy hybrids computed using anisotropic lattices.


title: New developments in inflationary models

abstract:
  We study models of inflation where the inflaton corresponds to a flat
direction in field space and its mass term is generated by gravity mediated
soft supersymmetry breaking at high scale. Assuming the inflaton to have non
negligible couplings to other fields, its mass runs with scale and can reach
the small value required by slow roll inflation at a lower scale, even if its
initial value is too large. Slow roll inflation can therefore take place in
such a regime, as long as the mass remains small, with a spectral index that is
then scale dependent. We explore the parameter space of this kind of models to
find the region compatible with the present observations.


title: Multibaryons in the Skyrme model

abstract:
  Low-lying multibaryon configurations are studied within the bound state
approach to the SU(3) Skyrme model. We use approximate ansaetze for the static
background fields based on rational maps which have the same symmetries of the
exact solutions. To determine the explicit form of the collective Hamiltonians
and wave functions we only make use of these symmetries. Thus, the expressions
obtained are also valid in the exact case. On the other hand, the meson
bindings, inertia parameters and hyperfine splitting constants we calculate do
depend on the detailed form of the ansaetze and are, therefore, approximate.
Using these values we compute the low-lying spectra of multibaryons with B =< 9
and strangeness 0 and -B. With these results the stability of some multilambda
configurations is discussed.


title: Electromagnetic and weak hyperon properties in the Skyrme model

abstract:
  We report on the result of some investigations concerning the radiative
decays of decuplet baryons and the non-leptonic weak decays of the octet
baryons in the context of topological chiral soliton models. Our results are
compared with those of alternative baryon models. For the radiative decays we
find that the predictions are similar to those of quark models. In the case of
the non-leptonic weak decays, we find that although the predicted S-wave
amplitudes are in rather good agreement with the observed values, the model is
not able to reproduce the empirical P-wave amplitudes. Thus, in contrast to
previous expectations, the Skyrme model does not seem to provide a solution to
the long-standing 'S-wave/P-wave puzzle'.


title: Nonperturbative corrections to moments of the decay B -> X_s l^+ l^-

abstract:
  We study nonperturbative corrections to the inclusive rare decay B -> X_s l^+
l^- by performing an operator product expansion (OPE) to O(1/m_b^3). The values
of the matrix elements entering at this order are unknown and introduce
uncertainties into physical quantities. We study uncertainties introduced into
the partially integrated rate, moments of the hadronic spectrum, as well as the
forward-backward asymmetry. We find that for large dilepton invariant mass q^2
> M_{\psi'}^2 these uncertainties are large. We also assess the possibility of
extracting the HQET parameters \lambda_1 and \bar{\Lambda} using data from this
process.


title: One-loop QCD corrected distribution in B to X+electron decays

abstract:
  We give an analytic formula for the double distribution of hadronic invariant
mass and charged lepton energy to one-loop order of the perturbative QCD.
Although infrared singular, this quantity is closely related to physical
observables that can be obtained thereof through proper convolution.


title: Cosmology of Brane Models with Radion Stabilization

abstract:
  We analyze the cosmology of the Randall-Sundrum model and that of compact
brane models in general in the presence of a radius stabilization mechanism. We
find that the expansion of our universe is generically in agreement with the
expected effective four dimensional description. The constraint (which is
responsible for the appearance of non-conventional cosmologies in these models)
that must be imposed on the matter densities on the two branes in the theory
without a stabilized radius is a consequence of requiring a static solution
even in the absence of stabilization. Such constraints disappear in the
presence of a stablizing potential, and the ordinary FRW
(Friedmann-Robertson-Walker) equations are reproduced, with the expansion
driven by the sum of the physical values of the energy densities on the two
branes and in the bulk. For the case of the Randall-Sundrum model we examine
the kinematics of the radion field, and find that corrections to the standard
FRW equations are small for temperatures below the weak scale. We find that the
radion field has renormalizable and unsuppressed couplings to Standard Model
particles after electroweak symmetry breaking. These couplings may have
important implications for collider searches. We comment on the possibility
that matter off the TeV brane could serve as a dark matter candidate.


title: Testing models with non-minimal Higgs sector through the decay t->q+WZ

abstract:
  We study the contribution of charged Higgs boson to the rare decay of the top
quark t->q+WZ (q=d,s,b) in models with Higgs sector that includes doublets and
triplets. Higgs doublets are needed to couple charged Higgs with quarks,
whereas the Higgs triplets are required to generate the non-standard vertex HWZ
at tree-level. It is found that within a model that respect the custodial SU(2)
symmetry and avoids flavour changing neutral currents by imposing discrete
symmetries, the decay mode t->b+WZ, can reach a branching ratio of order
0.0178, whereas the decay modes t->(d,s)+WZ, can reach a similar branching
ratio in models where flavour changing neutral currents are suppressed by
flavour symmetries.


title: Quark Matter 99 Summary: Hadronic Signals

abstract:
  I review the new data presented at QM99. The main emphasis is placed on the
CERN SPS hadron production systematics concluding that the boundary between a
partonic and a hadronic phase has now been located at $T=180 \pm10\:MeV$ and
$\epsilon \approx 1 \:GeV$ per $fm^3$.


title: Hadron yields from thermalized minijets at RHIC and LHC

abstract:
  We calculate the yields of pions, kaons, and $\phi$-mesons for RHIC and LHC
energies assuming thermodynamical equilibration of the produced minijets, and
using as input results from pQCD for the energy densities at midrapidity. In
the calculation of the production of partons and of transverse energy one has
to account for nuclear shadowing. By using two parametrizations for the gluon
shadowing one derives energy densities differing strongly in magnitude. In this
publication we link those perturbatively calculated energy densities of partons
via entropy conservation in an ideal fluid to the hadron multiplicities at
chemical freeze-out.


title: Decays of Positronium

abstract:
  We briefly review the theoretical and experimental results concerning decays
of positronium. Possible solutions of the "orthopositronium lifetime puzzle"
are discussed. Positronium annihilation into neutrinos is examined and
disagreement is found with previously published results.


title: Solving multi-loop Feynman diagrams using light-front coordinates

abstract:
  We determine the numerical values of scalar multi-loop two-vertex Feynman
diagrams, the generalized sunset diagrams, by integrating all but the
longitudinal momenta analytically. For the longitudinal momenta we introduce
one collective coordinate, which allows us to determine the numerical value of
the diagram efficiently and to an arbitrary accuracy. The imaginary part and
the threshold behavior of the diagram are also handled within this framework.


title: Compton scattering and polarizabilities of the nucleon

abstract:
  Fixed-$t$ subtracted dispersion relations are presented for Compton
scattering off the nucleon at energies $E_\gamma \leq 500$ MeV, as a formalism
to extract the nucleon polarizabilities from the data with a minimum of model
dependence. The scalar polarizabilities difference $\alpha - \beta$ and the
backward spin polarizability $\gamma_\pi$ enter directly as fit parameters in
this formalism.


title:
When semantics turns to substance: reformulating QCD analysis of
  F_2^{\gamma}(x,Q^2)}

abstract:
  QCD analysis of F_2^{\gamma}(x,Q^2) is revisited. It is emphasized that the
presence of the inhomogeneous term in the evolution equations for quark
distribution functions of the photon implies important difference in the way
factorization mechanism works in photon-hadron and photon-photon collisions as
compared to the hadronic ones. Moreover, a careful definitions of the very
concepts of the ``leading order'' and ``next-to-leading order'' QCD analysis of
F_2^{\gamma} are needed in order to separate genuine QCD effects from those of
pure QED origin. After presenting such definitions, I show that all existing
allegedly LO, as well as NLO analyses of F_2^{\gamma}(x,Q^2) are incomplete.
The source of this incompleteness of the conventional approach is traced back
to the lack of clear identification of QCD effects and to the misinterpretation
of the behaviour of q^{\gamma}(x,M) as a function of \alpha_s(M). Complete LO
and NLO QCD analyses of F_2^{\gamma}(x,Q^2) are shown to differ substantially
from the conventional ones. Whereas complete NLO analysis requires the
knowledge of two so far uncalculated quantities, a complete LO one is currently
possible, but compared to the conventional formulation requires the inclusion
of four known, but in the existing LO analyses unused quantities. The arguments
recently advanced in favour of the conventional approach are analyzed and shown
to contain a serious flaw. If corrected, they actually lends support to my
claim.


title:
Order alpha_s^3 ln^2(1/alpha_s) Corrections to Heavy-Quarkonium Creation
  and Annihilation

abstract:
  In the framework of nonrelativistic QCD, we compute the leading
double-logarithmic corrections of order alpha_s^3 ln^2(1/alpha_s) to the
heavy-quark-antiquark bound-state wave function at the origin, which determines
the production and annihilation rates of heavy quarkonia. The phenomenological
implications for the top-antitop and Upsilon systems are discussed.


title: Status and Perspectives of Indirect Search for Dark Matter

abstract:
  I summarize here and discuss the results of presently operating neutrino
telescopes in searching for a signal of dark matter weakly interacting massive
particles (WIMPs).


title: Asymptotic Series and Precocious Scaling

abstract:
  Some of the basic concepts regarding asymptotic series are reviewed. A
heuristic proof is given that the divergent QCD perturbation series is
asymptotic. By treating it as an asymptotic expansion we show that it makes
sense to keep only the first few terms. The example of e^+e^- annihilation is
considered. It is shown that by keeping only the first few terms one can get
within a per cent (or smaller) of the complete sum of the series even at very
low momenta where the coupling is large. More generally, this affords an
explanation of the phenomena of precocious scaling and why keeping only leading
order corrections generally works so well.


title:
The post-HERA era: brief review of future lepton-hadron and
  photon-hadron colliders

abstract:
  Options for future lp, lA, gamma-p, gamma-A and FEL gamma-A colliders are
discussed


title: Texture Zeros and Weak Basis Transformations

abstract:
  We investigate the physical meaning of some of the "texture zeros" which
appear in most of the Ansatze on quark masses and mixings. It is shown that
starting from arbitrary quark mass matrices and making a suitable weak basis
transformation one can obtain some of these sets of zeros which therefore have
no physical content. We then analyse the physical implications of a
four-texture zero Ansatz which is in agreement with all present experimental
data.


title:
Novel CP-violating Effects in B decays from Charged-Higgs in a Two-Higgs
  Doublet Model for the Top Quark

abstract:
  We explore charged-Higgs cp-violating effects in a specific type III
two-Higgs doublet model which is theoretically attractive as it accommodates
the large mass of the top quark in a natural fashion. Two new CP-violating
phases arise from the right-handed up quark sector. We consider CP violation in
both neutral and charged B decays. Some of the important findings are as
follows. 1) Large direct-CP asymmetry is found to be possible for B+- to psi/J
K+-. 2) Sizable D-anti-D mixing effect at the percent level is found to be
admissible despite the stringent constraints from the data on K-anti-K mixing,
b to s gamma and B to tau nu decays. 3) A simple but distinctive CP asymmetry
pattern emerges in decays of B_d and B_s mesons, including B_d to psi/J K_S, D+
D-, and B_s to D_s+ D_s-, psi eta/eta^prime, psi/J K_S. 4) The effect of
D-anti-D mixing on the CP asymmetry in B+- to D/anti-D K+- and on the
extraction of the angle gamma of the unitarity triangle from such decays can be
significant.


title:
Global observables and secondary interactions in central Au+Au reactions
  at $\sqrt{s}=200$ AGeV

abstract:
  The Ultra-relativistic Quantum Molecular Dynamics model (UrQMD) is used to
study global observables in central reactions of Au+Au at $\sqrt{s}=200$ AGeV
(RHIC). Strong stopping governed by massive particle production is predicted if
secondary interactions are taken into account. The underlying string dynamics
and the early hadronic decoupling implies only small transverse expansion
rates. However, rescattering with mesons is found to act as a source of
pressure leading to additional flow of baryons and kaons, while cooling down
pions.


title: Exponentially Small Supersymmetry Breaking from Extra Dimensions

abstract:
  The supersymmetric ``shining'' of free massive chiral superfields in extra
dimensions from a distant source brane can trigger exponentially small
supersymmetry breaking on our brane of order e^{-2 pi R}, where R is the radius
of the extra dimensions. This supersymmetry breaking can be transmitted to the
superpartners in a number of ways, for instance by gravity or via the standard
model gauge interactions. The radius R can easily be stabilized at a size O(10)
larger that the fundamental scale. The models are extremely simple, relying
only on free, classical bulk dynamics to solve the hierarchy problem.


title: Leptogenesis from R parity nonconservation

abstract:
  It is known that realistic neutrino masses for neutrino oscillations may be
obtained from R parity nonconserving supersymmetry. It is also known that such
interactions would erase any preexisting lepton or baryon asymmetry of the
Universe because of the inevitable intervention of the electroweak sphalerons.
We now show how a crucial subset of these R parity nonconserving terms may in
fact create its own successful leptogenesis.


title: On the Mixing Amplitude of J/psi and Vector Glueball O

abstract:
  We study the mixing angle \theta_{O\psi} and mixing amplitude f_{O\psi} of
J/psi and vector glueball O, in the framework of potential models of heavy
quarks and constituent gluons.
  While the state vectors of J/psi and O are constructed from the wave
functions of few-body Schroedinger equations, the mixing dynamics is governed
by perturbative QCD.
  We obtain a value of the mixing angle of |\tan \theta_{O\psi}| \approx 0.015
and the mixing amplitude of |f_{O\psi}(m_{O\psi}^2)| \approx 0.008 GeV^2, which
is compatible with phenomenological analysis.


title:
Polarized Parton Distributions in the Photon and Factorization Scheme
  Dependence

abstract:
  Spin-dependent parton distributions in the polarized virtual photon are
investigated in QCD up to the next-to-leading order (NLO). In the case
$\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2$ ($-P^2$) is the mass squared of the
probe (target) photon, parton distributions can be predicted completely up to
the NLO, but they are factorization-scheme-dependent. Parton distributions are
analyzed in four different factorization schemes and their scheme dependence
are discussed. Particular attentions are paid to the axial anomaly effect on
the first moments of quark parton distributions, and also to the large-$x$
behaviors of the parton distributions. Gluon distribution in the virtual photon
is found to be factorization-scheme independent up to the NLO.


title:
On the choice of heavy baryon currents in the relativistic three-quark
  model

abstract:
  We test the sensitivity of bottom baryon observables with regard to the
choice of the interpolating three-quark currents within the relativistic
three-quark model. We have found that the semileptonic decay rates are clearly
affected by the choice of currents, whereas the asymmetry parameters show only
a very weak dependence on the choice of current.


title: Hadronic structure, low x physics and diffraction

abstract:
  A review is presented of numerous recent results, particularly those
submitted to the EPS-HEP99 conference: very high Q^2 ep interactions and direct
tests of the Standard Model, new measurements of the structure of the proton
(including high x parton distributions and tests of QCD involving the gluon
distribution), low x physics (tests of the BFKL evolution), diffraction in DIS
at HERA, hard diffraction at the Tevatron and exclusive production of vector
particles at HERA. The focus is on hard QCD features.


title: Radiative leptonic decays of B mesons in QCD

abstract:
  We compute the form factors parametrizing radiative leptonic decays of heavy
mesons B^+\to\gamma e^+\nu for photon energies much larger than \Lambda_{QCD},
where perturbative QCD methods for exclusive processes can be combined with the
heavy quark effective theory. The form factors can be reliably obtained in this
region in an expansion in powers of \Lambda/E_\gamma. The leading term in this
expansion displays an additional spin symmetry manifested in the equality of
form factors of vector and axial currents. The leading twist form factors can
be written as the convolution of the B meson light-cone wave function with a
hard scattering amplitude, which is explicitly calculated to one-loop order.
The Sudakov double logarithms of the form
(\frac{\alpha_s}{\pi}\log^2\frac{2E_\gamma}{\Lambda})^n are resummed to all
orders. As an application we present a method for determining the CKM matrix
element |V_{ub}| from a comparison of photon spectra in B and D radiative
leptonic decays.


title:
Non-Equilibrium Steady States and Transport in the Classical Lattice
  $\phi ^4$ Theory

abstract:
  We study the classical non-equilibrium statistical mechanics of scalar field
theory on the lattice. Steady states are analyzed near and far from
equilibrium. The bulk thermal conductivity is computed, including its
temperature dependence. We examine the validity of linear response predictions,
as well as properties of the non-equilibrium steady state. We find that the
linear response theory applies to visibly curved temperature profiles as long
as the thermal gradients are not too strong. We also examine the transition
from local equilibrium to local non-equilibrium.


title:
Electroweak penguin amplitudes and constraints on $\gamma$ in charmless
  $B\to VP$ decays

abstract:
  Electroweak penguin (EWP) amplitudes are studied model-independently in $B$
meson decays to charmless final states consisting of a vector meson ($V$) and a
pseudoscalar meson ($P$). A set of SU(3) relations is derived between EWP
contributions and tree amplitudes, in the approximation of retaining only the
dominant EWP operators $Q_9$ and $Q_{10}$ . Two applications are described for
constraining the weak phase $\gamma$, in $B^{\pm}\to \rho^{\pm} K^0$ and
$B^{\pm}\to \rho^0 K^{\pm}$ (or $B^{\pm}\to K^{*\pm}\pi^0$ and $B^{\pm}\to
K^{*0}\pi^{\pm}$), and in $B^0\to K^{*\pm}\pi^{\mp}$ and $B^{\pm}\to\phi
K^{\pm}$. Theoretical uncertainties are discussed.


title: Classical $\phi^4$ Lattice Field Theory in Strong Thermal Gradients

abstract:
  The dynamics of classical $\phi^4$ theory under weak and strong thermal
gradients is studied. We obtain the thermal conductivity of the theory
including its temperature dependence. Under moderately strong thermal
gradients, the temperature profiles become visibly non-linear, yet the
phenomenon can be understood using the linear response theory. When we move
further away from equilibrium, we find that the linear response theory
eventually breaks down, and the concept of local equilibrium also fails.


title: Effective Potential of O(N) Linear Sigma Model at Finite Temperature

abstract:
  We study the O(N) symmetric linear sigma model at finite temperature as the
low-energy effective models of quantum chromodynamics(QCD) using the
Cornwall-Jackiw-Tomboulis(CJT) effective action for composite operators. It has
so far been claimed that the Nambu-Goldstone theorem is not satisfied at finite
temperature in this framework unless the large N limit in the O(N) symmetry is
taken. We show that this is not the case. The pion is always massless below the
critical temperature, if one determines the propagator within the form such
that the symmetry of the system is conserved, and defines the pion mass as the
curvature of the effective potential. We use a new renormalization prescription
for the CJT effective potential in the Hartree-Fock approximation. A numerical
study of the Schwinger-Dyson equation and the gap equation is carried out
including the thermal and quantum loops. We point out a problem in the
derivation of the sigma meson mass without quantum correction at finite
temperature. A problem about the order of the phase transition in this approach
is also discussed.


title:
Baryon-Pion Scattering in the 1/N_c Expansion: Tree Diagram
  Cancellations

abstract:
  Tree amplitudes for baryon-pion scattering are studied in the 1/N_c
expansion. Generalized large-N_c consistency conditions are obtained to all
orders in baryon mass splittings. For baryons with spin J ~ O(1), the leading
order in N_c tree amplitudes can be evaluated keeping only terms up to a given
finite order in baryon mass splittings.


title:
The color dipole BFKL-Regge expansion: from DIS on protons to pions to
  rise of hadronic cross sections

abstract:
  As noticed by Fadin, Kuraev and Lipatov in 1975 incorporation of asymptotic
freedom into the BFKL equation splits the QCD pomeron into a series of isolated
poles in complex angular momentum plane. Following our earlier work on the
proton structure function we explore the phenomenological consequences of the
emerging BFKL-Regge factorized expansion for the small-$x$ structure function
of the pion $F_{2\pi}(x,Q^2)$. We calculate $F_{2\pi}$ in a small-$x$ region
and find good agreement with the recent H1 determination of $F_{2\pi}(x,Q^2)$.
We also present the BFKL-Regge factorization based evaluation of the
contribution from hard scattering to the observed rise of the $NN$, $\pi N$ and
real photo-absorption $\gamma N$ and $\gamma \pi$ total cross sections.


title:
The relation between the $\bar{\rm MS}$ and the on-shell quark mass at
  order $\alpha_s^3$

abstract:
  The relation between the on-shell and $\bar{\rm MS}$ mass can be expressed
through scalar and vector part of the quark propagator. In principle these
two-point functions have to be evaluated on-shell which is a non-trivial task
at three-loop order. Instead, we evaluate the quark self energy in the limit of
large and small external momentum and use conformal mapping in combination with
Pad\'e improvement in order to construct a numerical approximation for the
relation [1]. The errors of our final result are conservatively estimated to be
below 3%. The numerical implications of the results are discussed in particular
in view of top and bottom quark production near threshold. We show that the
knowledge of new ${\cal O}(\alpha_s^3)$ correction leads to a significant
reduction of the theoretical uncertainty in the determination of the quark
masses.


title: Dynamical relaxation of the CP phases in next-to-minimal supersymmetry

abstract:
  After promoting the phases of the soft masses to dynamical fields
corresponding to Goldstone bosons of spontaneously broken global symmetries in
the supersymmetry breaking sector, the next-to-minimal supersymmetric model is
found to solve the $\mu$ problem and the strong CP problem simultaneously with
an invisible axion. The domain wall problem persists in the form of axionic
domain formation. Relaxation dynamics of the physical CP-violating phases is
determined only by the short-distance physics and their relaxation values are
not necessarily close to the CP-conserving points. Having observable
supersymmetric CP violation and avoiding the axionic domain walls both require
nonminimal flavor structures.


title: Polarization of Prompt J/psi at the Tevatron

abstract:
  The polarization of prompt J/psi at the Fermilab Tevatron is calculated
within the nonrelativistic QCD factorization framework. The contribution from
radiative decays of P-wave charmonium states decreases, but does not eliminate,
the transverse polarization at large transverse momentum. The angular
distribution parameter alpha for leptonic decays of the J/\psi is predicted to
increase from near 0 at p_T = 5 GeV to about 0.5 at p_T = 20 GeV. The
prediction is consistent with measurements by the CDF Collaboration at
intermediate values of p_T, but disagrees by about 3 standard deviations at the
largest values of p_T measured.


title: Electroweak Gauge Bosons at Future Electron-Positron Colliders

abstract:
  The interactions of electroweak gauge bosons are severely constrained by the
symmetries inferred from low energy observables. The exploration of the
dynamics of electroweak symmetry breaking requires therefore both an
experimental sensitivity and a theoretical precision that is better than the
natural scale of deviations from minimal extrapolations of the low energy
effective theory. Some techniques for obtaining improved theoretical
predictions for precision tests at a future e^+e^- linear collider are
discussed.


title: Form factors of pion and kaon

abstract: An addtional intrinsic form factors of pion and kaons have been studied.


title: Gauge mediated supersymmetry breaking and supergravity

abstract:
  We analyze simple models of gauge mediated supersymmetry breaking in the
context of supergravity. We distinguish two cases. One is when the messenger of
the supersymmetry breaking is a non Abelian gauge force and the other is when
the messenger is a pseudoanomalous U(1). We assume that these models originate
from string theory and we impose the constraint of the vanishing of the
cosmological constant requiring also the stabilization of the dilaton. In the
first case, we do not find vacua that are consistent with the constraints of
gauge mediation and have a zero tree level cosmological constant. In the second
case, no such conflict arises. In addition, by looking at the one loop
cosmological constant, we show that the dilaton F-term can not be neglected in
either case. For the gauge mediated case our considerations suggest that the
dilaton must be frozen out of the low energy field theory by non-perturbative
string dynamics.


title: Possible Accelerators @ CERN Beyond the LHC

abstract:
  The physics and world-wide accelerator context for possible accelerator
projects at CERN after the LHC are reviewed, including the expectation that an
e+ e- linear collider in the TeV energy range will be built elsewhere. Emphasis
is laid on the Higgs boson, supersymmetry and neutrino oscillations as
benchmarks for physics after the LHC. The default option for CERN's next major
project may be the CLIC multi-TeV e+ e- collider project. Also interesting is
the option of a three-step scenario for muon storage rings, starting with a
neutrino factory, continuing with one or more Higgs factories, and culminating
in a mu+ mu- collider at the high-energy frontier.


title: A Hypothesis on Production of Tachyons

abstract:
  An exact solution of the Einstein--Maxwell equations yields a general
relativistic picture of the tachyonic phenomenon, suggesting a hypothesis on
the tachyon creation. The hypothesis says that the tachyon is produced when a
neutral and very heavy (over 75 GeV/c^2) subatomic particle is placed in
electric and magnetic fields that are perpendicular, very strong (over 6.9 x
10^17 esu/cm^2 or oersted), and the squared ratio of their strength lies in the
interval (1,5]. Such conditions can occur when nonpositive subatomic particles
of high energy strike atomic nuclei other than the proton. The kinematical
relations for the produced tachyon are given. Previous searches for tachyons in
air showers and some possible causes of their negative results are discussed.
Experiments with the use of the strongest colliders and improvements in the air
shower experiments are suggested. An unfortunate terminology is also discussed.


title: Top-quark decay via R-parity violating interactions at the Tevatron

abstract:
  We consider the top-quark decay $t\to \tilde \tau b$ and $t\to \tau b
\tilde{\chi}^0_1$ via explicit R-parity violating interactions in SUSY
theories. We discuss the observability of those channels at the Fermilab
Tevatron collider. The existing Tevatron data indicate a 95% confidence level
upper bound on the coupling to be less than 0.94(0.63) for a long-lived
(short-lived) $\tilde{\chi}^0_1$ with $m_{\tilde\tau}=70$ GeV. At Tevatron Run
II with an integrated luminosity of 2 (10) fb$^{-1}$, one can obtain a
2$\sigma$ constraint as 0.38 (0.24) for a long-lived $\tilde{\chi}^0_1$ and
0.29(0.19) for a short-lived $\tilde{\chi}^0_1$, beyond the current indirect
limit.


title: Anomalous Higgs-Photon Interactions in Photon Fusion Processes at NLC

abstract:
  The Standard Model (SM) of the electroweak has proven to be successful in
describing all the available precision experimental data. However, the Higgs
mechanism, responsible for the electroweak symmetry breaking in the SM, still
remains one of the most important open questions of the theory. The effect of
new operators that give rise to anomalous Higgs boson coupling to two photons
(HAA) is examined in the two-photon processes AA -> H \to bb, AA,W+W-,ZZ at a
high energy linear e+ e- collider (NLC).


title: gamma-gamma Physics at Linear Colliders

abstract:
  A high-energy lepton-lepton collider will give us a unique possibility to
study e-gamma and gamma-gamma interactions at high energies. The high-energy
photons can be generated by Compton back-scattering of laser light on the
high-energy lepton beams. With slightly reduced luminosities for e-gamma and
gamma-gamma collisions compared to the lepton-lepton collider one, unique and
complementary studies can be performed. A linear lepton-lepton collider also
offers other photon sources that will be considered. We will focus on the
complex properties of the photon itself and discuss some possibilities to gain
new insight in its interactions at high energies and how to reveal the
structure of it.


title: Search for New Particles at LEP

abstract:
  The latest preliminary results of the searches for Higgs bosons and
Supersymmetric particles at LEP are reviewed. The results include the
data-taking in 1999 up to center-of-mass energies of 196 GeV. The combination
of the results from the four LEP experiments leads to a significant increase of
the detection sensitivity. No indication of a signal has been observed. In the
Standard Model (SM) a lower limit of 102.6 GeV on the mass of the Higgs boson
is set at 95% CL. In extended models, stringent limits are also set on the HZZ
coupling. Interpretations in the Minimal extension of the Supersymmetric
Standard Model (MSSM) are given and the importance of general MSSM parameter
scans is emphasized. In general scans, the limit on the mass of the lightest
scalar Higgs boson is about 7 GeV lower in comparison with benchmark results.
The data also constrains charged Higgs bosons of a general two-doublet model
and Supersymmetric partners of the SM particles.


title: Resonant Production of Topological Defects

abstract:
  We describe a novel phenomenon in which vortices are produced due to resonant
oscillations of a scalar field which is driven by a periodically varying
temperature T, with T remaining much below the critical temperature $T_c$.
Also, in a rapid heating of a localized region to a temperature {\it below}
$T_c$, far separated vortex and antivortex can form. We compare our results
with recent models of defect production during reheating after inflation. We
also discuss possible experimental tests of our predictions of topological
defect production {\it without} ever going through a phase transition.


title: Features in the primordial power spectrum of double D-term inflation

abstract:
  Recently, there has been some interest for building supersymmetric models of
double inflation. These models, realistic from a particle physics point of
view, predict a broken-scale-invariant power spectrum of primordial
cosmological perturbations, that may explain eventual non-trivial features in
the present matter power spectrum. In previous works, the primordial spectrum
was calculated using analytic slow-roll approximations. However, these models
involve a fast second-order phase transition during inflation, with a stage of
spinodal instability, and an interruption of slow-roll. For our previous model
of double D-term inflation, we simulate numerically the evolution of quantum
fluctuations, taking into account the spinodal modes, and we show that the
semi-classical approximation can be employed even during the transition, due to
the presence of a second inflaton field. The primordial power spectrum
possesses a rich structure, and possibly, a non-Gaussian spike on observable
scales.


title:
Inclusive Decays of B Mesons into D_s and $D_s^{\ast}$ at $O(\alpha_s)$
  Including $D_s^{\ast}$ Polarization Effects

abstract:
  The dominant contribution to the inclusive decays of $B$ mesons into the
charm-strangeness mesons $D_s$ and $D_s^{\ast}$ is expected to be given by the
partonic process $b \to c+(D_s^-,D_s^{\ast -})$. We determine the
nonperturbative $O(1/m_b^2)$ and the $O(\alpha_s)$ radiative corrections to $b
\to c+(D_s^-,D_s^{\ast -})$ and thereby to the inclusive decays $ \bar{B} \to
X_c+(D_s^-,D_s^{\ast -})$. The new feature of our calculation is that we
separately determine the nonperturbative and the $O(\alpha_s)$ corrections to
the longitudinal ($L$) and transverse ($T$) pieces of the spin 1 $D_s^{\ast -}$
meson. The longitudinal/transverse composition of the $D_s^{\ast -}$ can be
probed through its two principal decay modes $D_s^{\ast -} \to D_s^- + \gamma$
and $D_s^{\ast -} \to D_s^- + \pi^0$ for which we write down the angular decay
distributions.


title: A Brief Introduction to Chiral Perturbation Theory

abstract:
  A brief introduction to the subject of chiral perturbation theory ($\chi$pt)
is presented, including a discussion of effective field theory and applications
of $\chi$pt in the arena of purely mesonic interactions as well as in the $\pi
N$ sector.


title: The Dimensions of Field Theory : From Particles to Strings

abstract:
  This is an editorial summary of the contents of a Book comprising a set of
Articles by acknowledged experts dealing with the impact of Field Theory on
major areas of physics (from elementary particles through condensed matter to
strings), arranged subjectwise under six broad heads. The Book which emphasizes
the conceptual, logical and formal aspects of the state of the art in these
respective fields, carries a Foreword by Freeman Dyson, and is to be published
by the Indian National Science Academy on the occasion of the International
Mathematical Year 2000. The authors and full titles of all the Articles (33)
are listed sequentially (in the order of their first appearance in the
narration) under the bibliography at the end of this Summary, while a few of
the individual articles to appear in the Book are already available on the LANL
internet.


title:
Dispersion relations at finite temperature and density for nucleons and
  pions

abstract:
  We calculate the nucleonic and pionic dispersion relations at finite
temperature T and non-vanishing chemical potentials $(\mu_f)$ in the context of
an effective chiral theory that describes the strong and electromagnetic
interactions for nucleons and pions. The dispersion relations are calculated in
the broken chiral symmetry phase, where the nucleons are massive and pions are
taken as massless. The calculation is performed at lowest order in the energy
expansion, working in the framework of the real time formalism of thermal field
theory in the Feynman gauge. These one-loop dispersion relations are obtained
at leading order with respect to T and $\mu_f$. We also evaluate the effective
masses of the quasi-nucleon and quasi-pion excitations in thermal and chemical
conditions as the ones of a neutron star.


title:
Radiative corrections to pair production of charged Higgs bosons at
  TESLA

abstract:
  Charged Higgs particles are a common feature of many extensions of the
Standard Model. While its existence with masses up to the TeV scale can be
probed at the Tevatron Run II and LHC hadron colliders, a precise determination
of its properties would have to wait for a high energy e+e- linear collider. We
have computed the complete one-loop electroweak corrections to the
cross-section for charged Higgs bosons pair production in e+e- collisions, in
the framework of general Two Higgs Doublet Models, as well as the Minimal
Supersymmetric Standard Model. A study is presented for typical values of the
model parameters, showing the general behaviour of the corrections.


title:
Test particle description of transport processes for states with a
  continuous mass spectrum

abstract:
  Aiming at a description of transport processes where the dynamically
generated width of the states is potentially large a transport equation beyond
the quasiparticle approximation is derived in first order gradient expansion.
An effective particle number is identified which is exactly conserved by the
coarse grained transport equation. Using a test particle ansatz for this
conserved quantity allows to rewrite the transport equation into equations of
motion for test particles. The two-body collision terms are formulated in terms
of the test particles which gain non-trivial renormalization factors due to the
coarse graining process.


title: Light Quark Masses 99

abstract:
  I give a short historical and a critical review of the determinations of
light quark masses from QCD at dawn of the next millennium. QCD spectral sum
rules combined with ChPT give, to order $\alpha_s^3$, the world average for the
running masses: $\bar{m}_s$(2 GeV)= $(118.9\pm 12.2)$ MeV,
$\bar{m}_d(2~{GeV})=(6.3\pm 0.8)$ MeV, $\bar{m}_u(2~{GeV})=(3.5\pm 0.4)$ MeV
and the corresponding values of the invariant masses given in Eq. 24. Lower and
upper bounds derived from the positivity of spectral moments are presented in
Tables 2 and 3. For a comparison, we critically review the recent lattice
results (section 8 and Table 5) and attempt to deduce the present {\it QCD
grand average} determination (Table 6): $\bar{m}_s$(2 GeV)= $(110.9\pm 8.8)$
MeV, to be used with a great care. Then, we deduce the value:
$B_6^{1/2}-0.45(\rm resp.~0.32)B_8^{3/2}\simeq 1.6\pm 0.4~(\rm resp.~1.1\pm
0.3)$ and the lower bound $1.1\pm 0.2$ (resp. $0.7\pm 0.1$), for the
combination of the penguin operators, governing the CP-violating parameters
$\epsilon'/\epsilon$ without (resp. with) the inclusion of the final state
interaction effects. The result signals a possible deviation from the leading
1/N prediction by about $1\sim 3\sigma$, which should be tested using accurate
non-perturbative calculations.


title: Positronium properties

abstract:
  This talk gives an elementary introduction to the basic properties of
positronium. Recent progress in theoretical studies of the hyperfine splitting
and lifetime of the ground state is reviewed. Sensitivity of these precisely
measured quantities to some New Physics effects is discussed.


title: Analytic Approach to Perturbative QCD

abstract:
  The two-loop invariant (running) coupling of QCD is written in terms of the
Lambert W function. The analyticity structure of the coupling in the complex
Q^2-plane is established. The corresponding analytic coupling is reconstructed
via a dispersion relation. We also consider some other approximations to the
QCD beta-function, when the corresponding couplings are solved in terms of the
Lambert function. The Landau gauge gluon propagator has been considered in the
renormalization group invariant analytic approach (IAA). It is shown that there
is a nonperturbative ambiguity in determination of the anomalous dimension
function of the gluon field. Several analytic solutions for the propagator at
the one-loop order are constructed. Properties of the obtained analytical
solutions are discussed.


title: Phenomenology of a Stabilized Modulus

abstract:
  We explore the phenomenology of a stabilized modulus field in the
Randall-Sundrum scenario. It is found that if the large separation between
branes arises from a small bulk scalar mass then the modulus (i.e. radion) is
likely to be lighter than the lowest Kaluza-Klein excitations of bulk fields,
and consequently may be the first direct signature of the model.
Four-dimensional general covariance completely determines the couplings of the
modulus to Standard Model fields. The strength of these couplings is determined
by a single parameter which is set by the TeV rather than the Planck scale.


title:
Bounds on the Solar Antineutrino total Flux and Energy spectrum from the
  SK experiment

abstract:
  A search for inverse beta decay electron antineutrinos has been carried out
using the 825 days sample of solar data obtained at SK. The absence of a
significant signal, that is, contributions to the total SK background and their
angular variations has set upper bounds on a) the absolute flux of solar
antineutrinos originated from ${}^8 B$ neutrinos $\Phi_{\bar{\nu}}({}^8 B)=<
1.8\times 10^5 cm^{-2} s^{-1}$ which is equivalent to an averaged conversion
probability bound of P<3.5% (SSM-BP98 model) and b) their differential energy
spectrum, the conversion probability is smaller than 8% for all $E_{e,vis}>6.5$
MeV going down the 5% level above $E_{e,vis}\approx 10$ MeV. It is shown that
an antineutrino flux would have the net effect of enhancing the SK signal at
{\em hep} neutrino energies. The magnitude of this enhancement would highly
depend on the, otherwise rather uncertain, steepness of the solar neutrino
spectrum at these energies.


title:
Charged-Lepton-Flavour Violation in the Light of the Super-Kamiokande
  Data

abstract:
  Motivated by the data from Super-Kamiokande and elsewhere indicating
oscillations of atmospheric and solar neutrinos, we study
charged-lepton-flavour violation, in particular the radiative decays mu -> e
gamma and tau -> mu gamma, but also commenting on mu -> 3e and tau -> 3 mu/e
decays, as well as mu - e conversion on nuclei. We first show how the
renormalization group may be used to calculate flavour-violating soft
supersymmetry-breaking masses for charged sleptons and sneutrinos in models
with universal input parameters. Subsequently, we classify possible patterns of
lepton-flavour violation in the context of phenomenological neutrino mass
textures that accommodate the Super-Kamiokande data, giving examples based on
Abelian flavour symmetries. Then we calculate in these examples rates for mu ->
e gamma and tau ->mu gamma, which may be close to the present experimental
upper limits, and show how they may distinguish between the different generic
mixing patterns. The rates are promisingly large when the soft
supersymmetry-breaking mass parameters are chosen to be consistent with the
cosmological relic-density constraints. In addition, we discuss mu -> e
conversion on Titanium, which may also be accessible to future experiments.


title:
Electroweak-boson hadroproduction at large transverse momentum:
  factorization, resummation, and NNLO corrections

abstract:
  We study the resummation of singular distributions for electroweak-boson
production at large transverse momentum in hadronic collisions. We describe the
factorization properties of the cross section near partonic threshold and
construct the resummed cross section at next-to-leading logarithmic accuracy in
moment space in terms of soft gluon anomalous dimensions. We present full
analytical results for the expansion of the resummed cross section up to
next-to-next-to-leading order. Our results can be applied to W, Z, and virtual
gamma production at hadron colliders.


title: Charm Effects in the $\bar{MS}$ Bottom Quark Mass from $\Upsilon$ Mesons

abstract:
  We study the shift in the $\Upsilon$ mass due to a non-zero charm quark mass.
This shift affects the value of the $\bar{\rm MS}$ $b$-quark mass extracted
from the $\Upsilon$ system by about -20 MeV, due to an incomplete cancellation
of terms that are non-analytic in the charm quark mass. The precise size of the
shift depends on unknown higher order corrections, and might have a
considerable uncertainty if they are large.


title:
Magnetic Field Generation from Self-Consistent Collective
  Neutrino-Plasma Interactions

abstract:
  A new Lagrangian formalism for self-consistent collective neutrino-plasma
interactions is presented in which each neutrino species is described as a
classical ideal fluid. The neutrino-plasma fluid equations are derived from a
covariant relativistic variational principle in which finite-temperature
effects are retained. This new formalism is then used to investigate the
generation of magnetic fields and the production of magnetic helicity as a
result of collective neutrino-plasma interactions.


title:
Divergences in Real-Time Classical Field Theories at Non-Zero
  Temperature

abstract:
  The classical approximation provides a non-perturbative approach to
time-dependent problems in finite temperature field theory. We study the
divergences in hot classical field theory perturbatively. At one-loop, we show
that the linear divergences are completely determined by the classical
equivalent of the hard thermal loops in hot quantum field theories, and that
logarithmic divergences are absent. To deal with higher-loop diagrams, we
present a general argument that the superficial degree of divergence of
classical vertex functions decreases by one with each additional loop: one-loop
contributions are superficially linearly divergent, two-loop contributions are
superficially logarithmically divergent, and three- and higher-loop
contributions are superficially finite. We verify this for two-loop SU(N)
self-energy diagrams in Feynman and Coulomb gauges. We argue that hot,
classical scalar field theory may be completely renormalized by local (mass)
counterterms, and discuss renormalization of SU(N) gauge theories.


title:
Renormalization Group Evolution and Infra-red Fixed Points in Minimal
  Supersymmetric Standard Model with Baryon and Lepton Number Violation

abstract:
  We study the renormalization group evolution and infra-red stable fixed
points of the Yukawa couplings and the soft supersymmetry breaking trilinear
couplings of the minimal supersymmetric standard model with baryon and lepton
number (and R-parity) violation involving the heaviest generations. We show
analytically that in the Yukawa sector there is only one infra-red stable fixed
point. This corresponds to non-trivial fixed point for the top-, bottom-quark
Yukawa couplings and the $B$ violating coupling $\lambda_{233}''$, and a
trivial one for the $\tau$-Yukawa coupling. All other possible fixed points are
either unphysical or unstable in the infra-red region. We then carry out an
analysis of the renormalization group equations for the soft supersymmetry
breaking trilinear couplings, and determine the corresponding fixed points for
these couplings. We also study the quasi-fixed point behaviour, both
algebraically and with numerical solutions of the evolution equations, of the
third generation Yukawa couplings and the baryon number violating coupling, and
those of the soft supersymmetry breaking trilinear couplings. From the analysis
of the fixed point behaviour, we obtain upper and lower bounds on the baryon
number violating coupling $\lambda_{233}''$, as well as on the supersymmetry
breaking trilinear couplings.


title:
3-Neutrino Mass Spectrum from Combining Seesaw and Radiative Neutrino
  Mass Mechanisms

abstract:
  We extend the Standard Model by adding a second Higgs doublet and a
right-handed neutrino singlet with a heavy Majorana mass term. In this model,
there are one heavy and three light Majorana neutrinos with a mass hierarchy
m_3 >> m_2 >> m_1 such that that only m_3 is non-zero at the tree level and
light because of the seesaw mechanism, m_2 is generated at the one-loop and m_1
at the two-loop level. We show that the atmospheric neutrino oscillations and
large mixing MSW solar neutrino transitions with $\Delta m^2_\mathrm{atm}
\simeq m_3^2$ and $\Delta m^2_\mathrm{solar} \simeq m_2^2$, respectively, are
naturally accommodated in this model without employing any symmetry.


title:
Searching for Rephase-Invariant CP- and CPT-violating Observables in
  Meson Decays

abstract:
  We present a general model-independent and rephase-invariant formalism that
cleanly relates CP and CPT noninvariant observables to the fundamental
parameters. Different types of CP and CPT violations in the K^0-, B^0-, B_s^0-
and D^0-systems are explicitly defined. Their importance for interpreting
experimental measurements of CP and CPT violations is emphasized. In
particular, we show that the time-dependent measurements allow one to extract a
clean signature of CPT violation.


title: On the range of validity of the QCD-improved parton model

abstract:
  Based on the world DIS data we extract the experimental F_2^p-F_2^n as a
function of Bjorken-x and photon virtuality Q^2, using two different methods.
Both methods lead to identical results. We find that the standard PDFs fail to
describe the experimental data below Q^2 < 7 GeV^2, which is much higher than
for F_2^p and F_2^d separately. The difference between PDFs and the
experimental data cannot be understood as due to nuclear effects in the
deuteron, and evidently suggests substantial nonsinglet higher-twist effects.
The trend of the experimental data is approximately explained by a recent
two-component model of the nucleon structure functions and suggests strong
Q^2-dependence of the Gottfried Sum, in disagreement with the parton model
interpretation. The large negative higher-twist effects can explain the
difference between the value of the Gottfied integral obtained recently by the
E866 Drell-Yan experiment at Fermilab and an older NMC result.


title: Supersymmetry Effects on High-Precision Electroweak Observables

abstract:
  I summarise the virtual effects of the new particles predicted by
supersymmetric extensions of the Standard Model on the high-precision
electroweak observables measured at LEP/SLC, the Tevatron and CLEO. I will then
discuss in some details the two-loop SUSY-QCD corrections to the $\rho$
parameter.


title: Diffractive hadron production and pomeron coupling structure

abstract:
  Large-distance effects, which lead to the spin-flip part of the hadron
-pomeron coupling in QCD -models, are discussed. We study spin asymmetries in
exclusive reactions and in diffractive $Q \bar Q$ and vector meson production
which are sensitive to the spin-dependent part of the pomeron coupling.


title:
Testing Flavor Changing Neutrino Interactions in Long Baseline
  Experiments

abstract:
  We have investigated the possibility of discerning mass from flavor changing
neutrino interactions induced $\nu_\mu \to \nu_\tau$ oscillations in the long
baseline neutrino experiments K2K and MINOS. We have found that for virtually
any value of the flavor conserving parameter $\epsilon^\prime$ it will be
possible to, independently, distinguish these two mechanisms at K2K, if the
flavor changing parameter $\epsilon$ is in the range $\epsilon \gsim 0.77$, and
at MINOS, if $\epsilon \gsim 0.2$. Moreover, if K2K measures a depletion of the
expected $\nu_\mu$ flux then MINOS will either observe or discard completely
flavor changing neutrino oscillations.


title: Single Spin Asymmetry in Heavy Flavor Photoproduction as a Test of pQCD

abstract:
  We analyze in the framework of pQCD the properties of the single spin
asymmetry in heavy flavor production by linearly polarized photons. At leading
order, the parallel- perpendicular asymmetry in azimuthal distributions of both
charm and bottom quark is predicted to be about 20% in a wide region of initial
energy. Our analysis shows that the next-to-leading order corrections
practically do not affect the Born predictions for the azimuthal asymmetry at
energies of the fixed target experiments. Both leading and next-to-leading
order predictions for the asymmetry are insensitive to within few percent to
theoretical uncertainties in the QCD input parameters: $m_{Q}$, $\mu_{R}$,
$\mu_{F}$, $\Lambda_{QCD}$ and in the gluon distribution function. We estimate
also nonperturbative contributions to azimuthal distributions due to the gluon
transverse motion in the target and the final quark fragmentation. Our
calculations show that nonperturbative corrections to a $B$-meson azimuthal
asymmetry are negligible. We conclude that measurements of the single spin
asymmetry would provide a good test of pQCD applicability to heavy flavor
production at fixed target energies.


title: Classical pion fields in the presence of source

abstract:
  Classical pion field similar to Disoriented Chiral Condensate (DCC) is
considered in the presence of the external source. This field is similar to DCC
in the sense that its isotopic orientation is specified with a single vector at
the whole space. We study the classical field solutions in the nonlinear
sigma-model both in the chiral limit with massless pion and for the finite pion
mass. In both cases the field resembles the Coulomb field of charged particle
however the nonlinear pion interactions lead to the existence of several
solutions. In the massless case and for the very small size of the source there
is the lot of classical solutions with finite discrete energies. In the more
realistic situation of large nucleus (heavy ion) there are no stable solutions
of the above type, but there is the possibility for the formation of the
quasistationary states. They can live for a long time slowly decaying through
the emission of very soft pions. The structure and the energies of these
solutions is investigated numerically.


title: A remark on sphaleron erasure of baryon asymmetry

abstract:
  We complete an existing result for how the baryon asymmetry left over after a
period of full thermal equilibrium depends on different lepton asymmetries.


title:
The Equation of State of Deconfined Matter at Finite Chemical Potential
  in a Quasiparticle Description

abstract:
  A quasiparticle description of the thermodynamics of deconfined matter,
reproducing both the perturbative limit and nonperturbative lattice QCD data at
finite temperature, is generalized to finite chemical potential. By a flow
equation resulting from Maxwell's relation, the equation of state is extended
from zero to non-zero quark densities. The impact of the massive strange flavor
is considered and implications for cold, charge-neutral deconfined matter in
$\beta$-equilibrium in compact stars are given.


title:
A technique for loop calculations in non-Abelian gauge theories - with
  application to five gluon amplitude

abstract:
  A powerful tool for calculations in non-Abelian gauge theories is obtained by
combining the background field gauge, the helicity basis and the color
decomposition methods. It has reproduced the one-loop calculation of the
five-gluon amplitudes in QCD, is applicable to electroweak processes and
extendable to two-loop calculations.


title: Universality in nuclear dependence coefficient $\alpha(q_T)$

abstract:
  We derive the nuclear dependence coefficient $\alpha(q_T)$ for Drell-Yan and
J/$\psi$ production. We show that at small $q_T$, the $\alpha(q_T)$ is given by
an universal functional form: $\alpha(q_T)=a+b q_T^2$, and the parameters $a$
and $b$ are completely determined by either perturbatively calculable or
independently measurable quantities. This universal functional form
$\alpha(q_T)$ is insensitive to the $A$, and is consistent with existing data.


title: On the Top Mass Reconstruction Using Leptons

abstract:
  I discuss the feasibility of measuring the top quark mass by the using of
final states with leptons and J/\psi at hadron colliders. I also investigate
the impact of matrix-element corrections to the HERWIG simulation of top
decays.


title: b-quark decay in the collinear approximation

abstract:
  The semileptonic decay of a b-quark, b--> c l nu, is considered in the
relativistic limit where the decay products are approximately collinear.
Analytic results for the double differential lepton energy distributions are
given for finite charm-quark mass. Their use for the fast simulation of
isolated lepton backgrounds from heavy quark decays is discussed.


title:
Constraints on R-parity violating couplings from LEP/SLD hadronic
  observables

abstract:
  We analyze the one loop corrections to hadronic Z decays in an R-parity
violating extension to the Minimal Supersymmetric Standard Model (MSSM).
Performing a global fit to all the hadronic observables at the Z-peak, we
obtain stringent constraints on the R-violating couplings constants lambda' and
lambda''. As a result of the strong constraints from the b asymmetry parameters
A_b and A_FB(b), we find that the couplings lambda'{i31}, lambda'{i32}, and
lambda''{321} are ruled out at the 1 sigma level, and that lambda'{i33} and
lambda''{33i} are ruled out at the 2 sigma level. We also obtain Bayesian
confidence limits for the R-violating couplings.


title: New anomalous trajectory in Regge theory

abstract:
  We show that a new Regge trajectory with \alpha_{f_1} (0) \approx 1 and slope
\alpha_{f_1}'(0) \approx 0 explains the features of hadron-hadron scattering
and photoproduction of the rho and phi mesons at large energy and momentum
transfer. This trajectory with quantum numbers P = C = +1 and odd signature can
be considered as a natural partner of the Pomeron which has even signature. The
odd signature of the new exchange leads to contributions to the spin-dependent
cross sections, which do not vanish at large energy. The links between the
anomalous properties of this trajectory, the axial anomaly and the flavor
singlet axial vector f_1 (1285) meson are discussed.


title:
Analytic Solutions to the RG Equations of the Neutrino Physical
  Parameters

abstract:
  In the case of two generation neutrinos, the energy-scale dependence of the
lepton-flavor mixing matrix with Majorana phase can be governed by only one
parameter r, which is the ratio between the diagonal elements of neutrino mass
matrix. By using this parameter r, we derive the analytic solutions to the
renormalization group equations of the physical parameters, which are the
mixing angle, Majorana phase, and the ratio of the mass-squared difference to
the mass squared of the heaviest neutrino. The energy-scale dependence of the
Majorana phase is clarified by using these analytic solutions. The instability
of the Majorana phase causes in the same parameter region in which the mixing
angle is unstable against quantum corrections.


title:
Unstable Particles and Non-Conserved Currents: a Generalization of the
  Fermion-Loop Scheme

abstract:
  A generalization of the Fermion-Loop scheme is introduced to account for
external, non-conserved, currents. Complete Dyson re-summed transitions are
introduced, including the contributions from the Higgs-Kibble ghosts in the 't
Hooft-Feynman gauge. Running vector boson masses are introduced and their
relation with the corresponding complex poles are investigated. It is shown
that any S-matrix element takes a very simple form when written in terms of
these running masses. A special example of Ward identity, the U(1) Ward
identity for single-W, is derived in a situation where all currents are
non-conserved and where the top quark mass is not neglected inside loops.


title: Four and Six Fermion Event Generators for e^+e^- Collider Physics

abstract:
  The status of four and six fermion event generators for Standard Model
processes at present and future e^+e^- colliders is briefly reviewed.


title:
Comment on the paper: ``Feynman-Schwinger representation approach to
  nonperturbative physics'' by C. Savkli et al. [Phys. Rev. C 60, 055210
  (1999), hep-ph/9906211]

abstract:
  We point out that the scalar Wick-Cutkosky model (with $\chi^2 \phi$
interaction) used in this study has been known for a long time to be unstable.
However, the numerical results presented in this paper do not show any sign of
this instability which casts some doubt on their reliability. We compare with
the worldline variational approach.


title: Comments on the Instanton Size Distribution

abstract:
  By studying the non-linear effects of overlapping instanton pairs we address
difficulties in the identification of instanton distributions when the average
instanton size is comparable to the average distance. For the exact charge two
solution, we study how its parametrisation relates to a description in terms of
individual instantons. There exist two dual sets of parameters describing the
same charge two instanton solution. This duality implies the existence of a
minimal separation between two instantons. Conventionally used lattice
instanton finder algorithms based on the assumption of diluteness tend to
underestimate instanton sizes. Finally we numerically confirm this for
realistic parameters of the instanton liquid. The effect is enhanced by
parallel orientation in group space.


title: ELFE Physics

abstract:
  This is an introductory review of central topics in hadron physics that are
addressed by high intensity, continuous electron beam facilities in the
multi-GeV range. Exclusive processes are a crucial tool for increasing our
knowledge of hadron wave functions beyond what can be learned from studies of
hard inclusive processes. Data shows precocious scaling, suggesting a simple
underlying picture. Important conceptual advances in the application of PQCD is
being made.


title: Supersymmetric Models with Approximate CP

abstract:
  Supersymmetric models with an approximate CP, $10^{-3} \lsim \phi_{CP} \ll
1$, are a viable framework for the description of nature. The full high energy
theory has exact CP and horizontal symmetries that are spontaneously broken
with a naturally induced hierarchy of scales, $\Lambda_{CP} \ll \Lambda_{H}$.
Consequently, the effective low energy theory, that is the supersymmetric
Standard Model, has CP broken explicitly but by a small parameter. The
$\epsilon_{K}$ parameter is accounted for by supersymmetric contributions. The
predictions for other CP violating observables are very different from the
Standard Model. In particular, CP violating effects in neutral B decays into
final CP eigenstates such as $B \to \psi K_{S}$ and in $K \to \pi\nu\bar{\nu}$
decays are very small. This framework, though, is strongly disfavored by the
recent measurements of $\epsilon^\prime_{K}/\epsilon_{K}$.


title: Electroweak Baryogenesis in a Cold Universe

abstract:
  We discuss the possibility of generating the baryon asymmetry of the Universe
when the temperature of the Universe is much below the electroweak scale. In
our model the evaporation of primordial black holes or the decay of massive
particles re-heats the surrounding plasma to temperatures above the electroweak
transition temperature leading to the restoration of electroweak symmetry
locally. The symmetry is broken again spontaneously as the plasma cools and a
baryon asymmetry is generated during the phase transition. This mechanism
generates sufficient asymmetry for a second order electroweak phase transition.
For a first order phase transition, sufficient asymmetry is generated if
viscous effects slow down the heated plasma as it moves away from the black
hole. In our scenario there is no wash-out of the asymmetry after the phase
transition as the plasma rapidly cools to lower temperatures thereby shutting
off the sphaleron processes.


title:
Non-conserved currents and gauge-restoring schemes in single W
  production

abstract:
  We generalize the inclusion of the imaginary parts of the fermionic one-loop
corrections for processes with unstable vector bosons to the case of massive
external fermions and non conservation of weak currents. We study the effect of
initial and final state fermion masses in single W production in connection
with the gauge-invariant treatment of the finite-width effects of W and Z
bosons, giving numerical comparisons of different gauge-invariance-preserving
schemes in the energy range of LEP2 and LC for e+e- -> e- v u d. We do not find
significant differences between the results obtained in the imaginary part
fermion loop scheme and in other exactly gauge preserving methods.


title: Perturbative heavy quark-antiquark systems

abstract:
  In this review I cover recent developments concerning the construction of
non-relativistic effective theories for perturbative heavy quark-antiquark
systems and heavy quark mass definitions. I then discuss
next-to-next-to-leading order results on quarkonium masses and decay, top quark
pair production near threshold and QCD sum rules for $\Upsilon$ mesons.


title: Renormalisation of the Fayet-Iliopoulos D-term

abstract:
  We consider the renormalisation of the Fayet-Iliopoulos D-term in a
softly-broken Abelian supersymmetric theory. We show that there exists (at
least through three loops) a renormalisation group invariant trajectory for the
coefficient of the D-term, corresponding to the conformal anomaly solution for
the soft masses and couplings.


title: An Optimised Perturbation Expansion For a Global O(2) Theory

abstract:
  We use an optimised perturbation expansion called the linear delta-expansion
to study the phase transition in a Higgs sector with a continuous symmetry and
large couplings. Our results show how to use this non-perturbative method
successfully for such problems. We also show how to simplify the method without
losing any flexibility.


title: Narrow muon bundles from muon pair production in rock

abstract:
  We revise the process of muon pair production by high-energy muons in rock
using the recently published cross-section. The three-dimensional Monte Carlo
code MUSIC has been used to obtain the characteristics of the muon bundles
initiated via this process. We have compared them with those of conventional
muon bundles initiated in the atmosphere and shown that large underground
detectors, capable of collecting hundreds of thousands of multiple muon events,
can discriminate statistically muon induced bundles from conventional ones.
However, we find that the enhancement of the measured muon decoherence function
over that predicted at small distances, recently reported by the MACRO
experiment, cannot be explained by the effect of muon pair production alone,
unless its cross-section is underestimated by a factor of 3.


title: Four-Point Spectral Functions and Ward Identities in Hot QED

abstract:
  We derive spectral representations for the different components of the
4-point function at finite temperature in the real time formalism in terms of
five real spectral densities. We explicitly calculate all these functions in
QED in the hard thermal loop approximation. The Ward identities obeyed by the
1-loop 3- and 4-point functions in real time and their spectral functions are
derived. We compare our results with those derived previously in the
imaginary-time formalism for retarded functions in hot QCD, and we discuss the
generalization of our results to non-equilibrium situations.


title: ep Physics with Heavy Flavours

abstract:
  Recent results from H1 and ZEUS on heavy flavour production at HERA are
reviewed


title: Light Scalar Top Quarks and Supersymmetric Dark Matter

abstract:
  A stable neutralino $\chi_1^0$, assumed to be the lightest supersymmetric
particle, is a favored particle physics candidate for the cosmological Dark
Matter. We study co-annihilation of the lightest neutralino with the lighter
scalar top quark $\tilde{t}_1$. We show that for natural values of the
neutralino mass, $\lsim 300$ GeV, the $\chi_1^0 - \tilde{t}_1$ mass difference
has to exceed $\sim 10$ to 30 GeV if $\chi_1^0$, is to contribute significantly
to the Dark Matter. Scenarios with smaller mass splitting, where $\tilde{t}_1$
is quite difficult to detect at collider experiments, are thus cosmologically
disfavored. On the other hand, for small $\tilde{t}_1 - \chi_1^0$ mass
splitting, we show that co--annihilation allows very large neutralino masses,
$m_{\chi_1^0} \sim 5$ TeV, without ``overclosing'' the Universe.


title:
Leptoquark Contribution to the Higgs Boson Production at the LHC
  Collider

abstract:
  In this report we study how a light-scalar leptoquark could affect the Higgs
boson production cross-section at the LHC collider. We construct the most
general renormalizable and gauge invariant effective Lagrangian involving the
standard model particles and a scalar, isoscalar leptoquark, \eta.
  The total cross-section for pp -> H+X is then calculated for different values
of the unknown parameters \lambda_eta, m_eta and m_H.(Here \lambda_eta is the
coupling associated with the Higgs-leptoquark interaction.)
  We find that if \lambda_eta is moderately large and m_eta is around a few
hundred GeV, then the cross-section is significantly larger than the standard
model value.


title: Inverse beta-decay in magnetic fields

abstract:
  We calculate the cross section of the inverse beta decay process, $\nu_e+n\to
p+e$, in a magnetic field which is much smaller than $m_p^2/e$. Using exact
solutions of the Dirac equation in a constant magnetic field, we find that the
cross section depends on the direction of the incident neutrino even when the
initial neutron is assumed to be at rest. We discuss the implication of this
result for pulsar kicks.


title: The second string (phenomenology) revolution

abstract:
  In the past three years our views on how the standard model of particle
physics could be embedded into string theory have dramatically changed. The
heterotic string is no longer the only possibility for such an embedding and
other perturbative (or non-perturbative) corners of M-theory, like Type I or
Type II strings seem now possible. It has also been realized that the string
scale $M_s$ is not necessary close to the Planck scale and could be much
smaller, of order the intermediate scale $\sqrt{M_WM_p}$ or even close to the
weak scale. In addition, semi-realistic three generation models have recently
been constructed starting with Type IIB compact orientifolds. I briefly discuss
some of these developements which represent a revolution in our understanding
of string phenomenology.


title: Six-jet production at e+e- linear colliders

abstract:
  The calculation of the tree-level QCD processes e+e- -> qqgggg, qqqqgg and
qqqqqq has recently been accomplished. We highlight here the relevance of such
reactions for some of the physics at future electron-positron linear
accelerators.


title:
Higgs radiation off top-antitop pairs at future Linear Colliders: a
  background study

abstract:
  The process e+e- -> Htt can be exploited at future Linear Colliders to
measure the Higgs-top Yukawa coupling. In this note, we estimate the size of
the irreducible backgrounds in the channel Htt -> bbbb WW -> bbbb ln qq, for
the case of a Standard Model Higgs boson with mass between 100 and 140 GeV.


title: Electromagnetic Decays of Heavy Baryons

abstract:
  The electromagnetic decays of the ground state baryon multiplets with one
heavy quark are calculated using Heavy Hadron Chiral Perturbation Theory. The
M1 and E2 amplitudes for S^{*}--> S gamma, S^{*} --> T gamma and S --> T gamma
are separately computed. All M1 transitions are calculated up to
O(1/Lambda_chi^2). The E2 amplitudes contribute at the same order for S^{*}-->
S gamma, while for S^{*} --> T gamma they first appear at O(1/(m_Q
\Lambda_\chi^2)) and for S --> T gamma are completely negligible. The
renormalization of the chiral loops is discussed and relations among different
decay amplitudes are derived. We find that chiral loops involving
electromagnetic interactions of the light pseudoscalar mesons provide a sizable
enhancement of these decay widths. Furthermore, we obtain an absolute
prediction for the widths of Xi^{0'(*)}_c--> Xi^{0}_c gamma and Xi^{-'(*)}_b-->
Xi^{-}_b gamma. Our results are compared to other estimates existing in the
literature.


title:
Analytic Model of a Regge Trajectory in the Space-like and Time-like
  Regions

abstract:
  A model for a Regge trajectory compatible with the threshold behavior
required by unitarity and asymptotics in agreement with Mandelstam analyticity
is analyzed and confronted with the experimental data on the spectrum of the
$\rho$ trajectory as well as those on the $\pi^- p\to \pi^0 n$ charge-exchange
reaction. The fitted trajectory deviates considerably from a linear one both in
the space-like and time-like regions, matching nicely between the two.