title: Precision Higgs physics at a $\gamma \gamma$ collider

abstract:
  The loop induced coupling of an intermediate mass Higgs boson to two photons
is a sensitive and unique measure for precision tests of physics beyond the
Standard Model. In this work we summarize recent results on the expected
precision of the partial $\Gamma (H \to \gamma \gamma)$ width at the $\gamma
\gamma$ option of a future linear collider. Heavy particles do not decouple in
general and differences between the SM and MSSM predictions or 2HD-models can
differ in the percentile regime. Large non-Sudakov DL corrections need to be
resummed and consistency requirements demand the use of the Sterman-Weinberg
jet definition in order to avoid additional DL terms from three jet final
states. We find that the well understood background process $\gamma \gamma \to
q \bar{q}$ allows for a ${\mathcal O}$(2%) determination of $\Gamma (H \to
\gamma \gamma)$ using conservative collider parameters. Recent improvements in
the expected $\gamma \gamma$ luminosity suggest that the precision for the
diphoton partial Higgs width can be further improved and is dominated by the
error in BR($H \to b \bar{b}$) from the $e^\pm$ mode, which is presently
estimated to be in the one percent regime.


title: Extra dimensions present a new flatness problem

abstract:
  There is no known fundamental reason to demand as a cosmological initial
condition that the bulk possess an SO(3,1) isometry. On the contrary, one
expects bulk curvature terms that violate the SO(3,1) isometry at early epochs,
leading to a violation of Lorentz invariance on our brane. Demanding that the
Lorentz noninvariant terms are small leads to a new ``flatness'' problem, not
solved by the usual formulation of inflation. Furthermore, unlike in four
dimensions, the Lorentz violations induced from the bulk curvature cannot
always be removed as the infrared cutoff is taken arbitrarily large. This means
that the equivalence principle in higher dimensions does not guarantee the
equivalence principle in dimensionally reduced theories. Near-future
experiments are expected to severely constrain these Lorentz-violating
``signatures'' of extra dimensions.


title: Higgs Particles in the Standard Model and Supersymmetric Theories

abstract:
  This thesis presents a theoretical analysis of the properties of the Higgs
bosons in the Standard Model (SM) and the minimal supersymmetric extension
(MSSM), which can be investigated at the LHC and $e^+e^-$ linear colliders. The
final goal is the reconstruction of the Higgs potential and thus the
verification of the Higgs mechanism. MSSM Higgs boson production processes at
future $\gamma\gamma$ colliders are calculated in several decay channels. Heavy
scalar and pseudoscalar Higgs bosons can be discovered in the $b\bar{b}$ final
state in the investigated mass range 200 to 800 GeV for moderate and large
values of $\tan\beta$. The $\tau^+\tau^-$ channel provides a heavy Higgs boson
discovery potential for large values of $\tan\beta$. Several mechanisms that
can be exploited at $e^+e^-$ linear colliders for the measurement of the
lifetime of a SM Higgs boson in the intermediate mass range are analysed. In
the $WW$ mode, the lifetime of Higgs scalars with masses below $\sim 160$ GeV
can be determined with an error less than 10%. The reconstruction of the Higgs
potential requires the measurement of the Higgs self-couplings. The SM and MSSM
trilinear Higgs self-couplings are accessible in double and triple Higgs
production. A theoretical analysis is presented in the relevant channels at the
LHC and $e^+e^-$ linear colliders. For high luminosities, the SM trilinear
Higgs self-coupling can be measured with an accuracy of 20% at a 500 GeV
$e^+e^-$ linear collider. The MSSM coupling among three light Higgs bosons has
to be extracted from continuum production. The other trilinear Higgs couplings
are measurable in a restricted range of the MSSM parameter space. At the LHC,
the $Hhh$ coupling can be probed in resonant decays.


title:
The use of configuration interaction method for describing fine-
  splitting effects in the bound two- quark system

abstract:
  The screened quasi-relativistic potential is used for describing spin-orbit
splitting in $^{3}P_{J}$ waves of quark-antiquark system. Fermi-Breit equation
is solved numerically in configuration interaction approximation. This
approximation takes into account the mixing of wave functions up to fifth order
and corrects substantially perturbation calculations. The nature of potentials
Lorenz transformation property is elucidated. Very good quantitative results
for $b\bar{b}$ and $c\bar{c}$ quarkonia and quite acceptable qualitative
characteristics as well as for systems with unequal masses are obtained for
$u\bar{u}$.


title:
Bimaximal Neutrino Mixing in a Zee-type Model with Badly Broken Flavor
  Symmetry

abstract:
  A Zee-type neutrino mass matrix model with a badly broken horizontal symmetry
SU(3)_H is investigated. By putting a simple ansatz on the symmetry breaking
effects of SU(3)_H for transition matrix elements, it is demonstrated that the
model can give a nearly bimaximal neutrino mixing with the ratio $\Delta
m^2_{solar}/\Delta m^2_{atm} \simeq \sqrt{2} m_e/m_{\mu}=6.7 \times 10^{-3}$,
which are in excellent agreement with the observed data. In the near future,
the lepton-number violating decay $Z\to \mu^\pm \tau^\mp$ will be observed.


title: The legacy of HERA - the first decade

abstract:
  The ep HERA collider started operation in summer of 1992. This talk
summarizes some of the highlights of physics results obtained since then and
discusses their impact on our understanding of Quantum Chromodynamics (QCD).


title: Meson loop effects in the NJL model at zero and non-zero temperature

abstract:
  We compare two different possibilities to include meson-loop corrections in
the Nambu-Jona-Lasinio model: a strict 1/N_c-expansion in next-to-leading order
and a non-perturbative scheme corresponding to a one-meson-loop approximation
to the effective action. Both schemes are consistent with chiral symmetry, in
particular with the Goldstone theorem and the Gell-Mann-Oakes-Renner relation.
The numerical part at zero temperature focuses on the pion and the rho-meson
sector. For the latter the meson-loop-corrections are crucial in order to
include the dominant rho -> pipi-decay channel, while the standard Hartree +
RPA approximation only contains unphysical qqbar-decay channels. We find that
m_\pi, f_\pi, <qbar q> and quantities related to the rho-meson self-energy can
be described reasonably with one parameter set in the 1/N_c-expansion scheme,
whereas we did not succeed to obtain such a fit in the non-perturbative scheme.
We also investigate the temperature dependence of the quark condensate. Here we
find consistency with chiral perturbation theory to lowest order. Similarities
and differences of both schemes are discussed.


title: Brane World Cosmology Without the Z_2 Symmetry

abstract:
  The Friedmann equation for a positive tension brane situated between two bulk
spacetimes that posses the same 5D cosmological constant, but which does not
posses a Z_2 symmetry of the metric itself is derived, and the possible effects
of dropping the Z_2 symmetry on the expansion of our Universe are examined;
cosmological constraints are discussed. The global solutions for the metric in
the infinite extra dimension case are found and comparison with the symmetric
case is made. We show that any brane world senario of this type must revert to
a Z_2 symmetric form at late times, and hence rule out certain proposed
scenarios.


title:
The abundance of relativistic axions in a flaton model of Peccei-Quinn
  symmetry

abstract:
  Flaton models of Peccei-Quinn symmetry have good particle physics motivation,
and are likely to cause thermal inflation leading to a well-defined cosmology.
They can solve the $\mu$ problem, and generate viable neutrino masses.
Canonical flaton models predict an axion decay constant F_a of order 10^{10}
GeV and generic flaton models give F_a of order 10^9 GeV as required by
observation. The axion is a good candidate for cold dark matter in all cases,
because its density is diluted by flaton decay if F_a is bigger than 10^{12}
GeV. In addition to the dark matter axions, a population of relativistic axions
is produced by flaton decay, which at nucleosynthesis is equivalent to some
number \delta N_\nu of extra neutrino species. Focussing on the canonical
model, containing three flaton particles and two flatinos, we evaluate all of
the flaton-flatino-axion interactions and the corresponding axionic decay
rates. They are compared with the dominant hadronic decay rates, for both DFSZ
and KSVZ models. These formulas provide the basis for a precise calculation of
the equivalent \delta N_\nu in terms of the parameters (masses and couplings).
The KSVZ case is probably already ruled out by the existing bound \delta
N_\nu\lsim 1. The DFSZ case is allowed in a significant region of parameter
space, and will provide a possible explanation for any future detection of
nonzero $\delta N_\nu$.


title: Floquet theory of neutrino oscillations in the earth

abstract:
  We review the Floquet theory of linear differential equations with periodic
coefficients and discuss its applications to neutrino oscillations in matter of
periodically varying density. In particular, we consider parametric resonance
in neutrino oscillations which can occur in such media, and discuss
implications for oscillations of neutrinos traversing the earth and passing
through the earth's core.


title: Summary talk at the conference on the sigma resonance

abstract:
  This report summarizes the most important results presented at the recent
conference held at the Yukawa Institute of Theoretical Physics in Kyoto,
devoted to the recently confirmed light sigma resonance. Remarkably, all
speakers at this meeting took the light sigma for granted and many mass and
width estimations near 500 MeV were presented. We emphasize that if the light
and broad sigma is accepted as a true resonance it explains many basic problems
of low energy hadronic physics in a simple way, especially if the linear sigma
model is used as an approximate effective low energy theory.


title: How to understand the lightest scalars

abstract:
  Based on previous papers I discuss how I understand the lightest scalars
using a general coupled channel model. This model includes all light
two-pseudoscalar thresholds, constraints from Adler zeroes, flavour symmetric
couplings, unitarity and physically acceptable analyticity. One finds that with
a large coupling there can appear two physical resonance poles on the second
sheet although only one bare quark-antiquark state is put in. The f0(980) and
f0(1370) resonance poles are thus in this model two manifestations of the same
strange-antistrange quark state. On the other hand, the isoscalar state
containing u and d quarks becomes (when unitarized and strongly distorted by
hadronic mass shifts) a very broad resonance, with its pole at 470-i250 MeV.
This is the sigma meson required by models for spontaneous breaking of chiral
symmetry.


title: The hydrogen Lamb shift and the proton radius

abstract:
  The Lamb shift measurement and theory are now both a dynamically developing
field and we give a review of the current data. Critical comparison of theory
and experiment can be done using a value of the proton charge radius and we pay
attention to several results of its determination.


title:
Heavy sterile neutrinos: Bounds from big-bang nucleosynthesis and SN
  1987A

abstract:
  Cosmological and astrophysical effects of heavy (10 - 200 MeV) sterile Dirac
neutrinos, mixed with the active ones, are considered. The bounds on mass and
mixing angle from both supernovae and big-bang nucleosynthesis are presented.


title:
Cosmological constraints on a Peccei-Quinn flatino as the lightest
  supersymmetric particle

abstract:
  In an interesting class of models, non-renormalizable terms of the
superpotential are responsible for the spontanteous breaking of Peccei-Quinn
(PQ) symmetry as well as the generation of the $\mu$ term. The flaton fields
which break PQ symmetry are accompanied by flatinos, and the lightest flatino
(the LSP) can be the stable, while the decay of the lightest neutralino (the
NLSP) might be visible at colliders with a low axion scale. We examine the
cosmology of these models, involving thermal inflation just after the PQ phase
transition. The branching ratio of flatons into axions must be small so as not
to interfere with nucleosynthesis, and flatons must not decay into the LSP or
it will be over-abundant. We explore a simple model,with light flatons which
can decay into $Z$ or $W$ bosons, or into a light Higgs ($h^0$) plus a $Z$
boson, to show that such features can be realized in a wide range of parameter
space. The mass of the NLSP can be as low as $(m_{h^0}+m_Z)/2$, with an axion
scale of order $10^{10}$ GeV and a final reheat temperature typically of order
$10\GeV$. Then, the flatino LSP is a good dark matter candidate because the
reheat temperature can be high enough to allow its production from the decay of
the thermalized LSP, while low enough to prevent its overproduction from the
decay of sfermions.


title:
Octet Baryon Charge Radii, Chiral Symmetry and Decuplet Intermediate
  States

abstract:
  We compute the octet baryon charge radii to O(1/Heavy^3) in heavy baryon
chiral perturbation theory. We examine the effect of including the decuplet of
spin-3/2 baryons explicitly. We find that it does no t improve the level of
agreement between the HBchiPT and experimental values for the Sigma^- charge
radius.


title: $h\to \mu\tau$ at Hadron Colliders

abstract:
  We study the observability for a lepton flavor-changing decay of a Higgs
boson $h\to \mu\tau$ at hadron colliders. Flavor-changing couplings of a Higgs
boson exist at tree level in models with multiple Higgs doublets. The
$h\mu\tau$ coupling is particularly motivated by the favorable intepretation of
$\nu_\mu-\nu_\tau$ oscillation. We find that at the Tevatron Run II the unique
$\mu\tau$ signature could serve as the Higgs discovery channel, surpassing
expectations for Higgs boson searches in the SM and in a large parameter region
of the MSSM. The sensitivity will be greatly improved at the LHC, beyond the
coverage at a muon collider Higgs factory.


title:
Electroweak baryogenesis in the standard model with strong hypermagnetic
  fields

abstract:
  We show that in the presence of large scale primordial hypermagnetic fields,
it is possible to generate a large amount of CP violation to explain the baryon
to entropy ratio during the electroweak phase transition within the standard
model. The mechanism responsible for the existence of a CP violating asymmetry
is the chiral nature of the fermion coupling to the background field in the
symmetric phase which can be used to construct two-fermion interference
processes in analogy to the Bohm-Aharanov effect. We estimate that for strong
hypermagnetic fields B_Y=(0.3-0.5)T^2 the baryon to entropy ratio can be
rho_B/s=(3 - 6)X10^-11 for slowly expanding bubble walls.


title: Universality limits on bulk fermions

abstract:
  The Kaluza-Klein fermion excitations induce mixing between the Standard Model
fermions and loss of universality. The flavour mixing not present in the
Standard Model can be made to vanish aligning the Yukawa couplings and the
Dirac masses of the heavy modes, but universality is only recovered when these
masses go to infinity. This implies a bound on the lightest new heavy quark, M1
\~ 3-5 TeV, which together with the electroweak precision data limits will
allow the Large Hadron Collider to provide a crucial test of the
Randall-Sundrum ansatz for solving the gauge hierarchy.


title: Neutrino Flavor Oscillations without Flavor Mixing Angles

abstract:
  We demonstrate that sizable neutrino flavor oscillations can be generated in
a model with large extra spacetime dimensions even if the physics on the brane
is flavor-diagonal, the bulk neutrino theory is flavor-neutral, and the
brane/bulk couplings are flavor-blind. This is thus a compact model for
addressing neutrino flavor oscillations in higher dimensions. We also discuss
several phenomenological aspects of the ``bulk-mediated'' neutrino oscillations
inherent in this model, and show that this model contains some potentially
important new phenomenological features in the limit of large brane/bulk
coupling.


title:
Latest cosmological constraints on the densities of hot and cold dark
  matter

abstract:
  As experimentalists step up their pursuit of cold dark matter particles and
neutrino masses, cosmological constraints are tightening. We compute the joint
constraints on 11 cosmological parameters from cosmic microwave background and
large scale structure data, and find that at 95% confidence, the total
(cold+hot) dark matter density is h^2 Omega_dark = 0.20 +.12 -.10 with at most
38% of it being hot (due to neutrinos). A few assumptions, including negligible
neutrinos, tighten this measurement to h^2 Omega_dark = 0.13 +0.04 -0.02, i.e,
2.4e-27 kg/m^3 give or take 20%.


title: Nuclear dependence asymmetries in direct photon production

abstract:
  We study the nuclear dependences of high-$p_T$ jet cross sections in one
photon and one jet production in proton-nucleus collisions. We find that there
exist asymmetries between the outgoing jets and photons. A convincing reason
responsible for those asymmetries are demonstrated in perturbative QCD.
Significant nuclear enhancements are also found in the inclusive jet cross
sections.


title: Regularizing the Divergent Structure of the Light-Front Currents

abstract:
  The divergences appearing in the 3+1 dimensional fermion-loop calculations
are often regulated by smearing the vertices in a covariant manner. Performing
a parallel light-front calculation, we corroborate the similarity between the
vertex-smearing-technique and the Pauli-Villars regularization. In the
light-front calculation of the electromagnetic meson current, we find that the
persistent end-point singularity that appears in the case of point vertices is
removed even if the smeared-vertex is taken to the limit of the point-vertex.
Recapitulating the current conservation, we substantiate the finiteness of both
valence and non-valence contributions in all components of the current with the
regularized bound-state vertex. However, we stress that each contribution,
valence or non-valence, depends on the reference-frame even though the sum is
always frame-independent. The numerical taxonomy of each contribution including
the instantaneous contribution and the zero-mode contribution is presented in
the $\pi$, $K$, and $D$-meson form factors.


title: Strangeness in Lattice QCD

abstract:
  The status of lattice calculations in the light hadron sector is reviewed.
Special emphasis is given to recent lattice determinations of the mass of the
strange quark. The impact of non-perturbative renormalization and control over
lattice artefacts on the attainable precision is discussed in detail.
Furthermore the influence of dynamical quark effects is assessed.


title: Results from pQCD for A+A collisions at RHIC & LHC energies

abstract:
  This talk will discuss how to compute initial quantites in heavy ion
collisions at RHIC (200 AGeV) and at LHC (5500 AGeV) using perturbative QCD
(pQCD) by including the next-to-leading order (NLO) corrections and a dynamical
determination of the dominant physical scale. The initial numbers are converted
into final ones by assuming kinetic thermalization and adiabatic expansion.


title: Spontaneously broken color

abstract:
  The vacuum of QCD is characterized by the Higgs mechanism. Color is
``spontaneously broken'' by a quark-antiquark condensate in the octet
representation. The massive gluons carry integer electric charges and are
identified with the vector mesons. The fermionic excitations consist of the low
mass baryon octet and a singlet. The interactions between these particles and
the light pseudoscalar octet are largely determined by chiral symmetry and a
nonlinear local symmetry. A consistent phenomenological picture of strong
interactions at long distances arises from a simple effective action.


title:
Extra dimensions at the one loop level: Z -> b,b(bar) and B-B(bar)
  mixing

abstract:
  We study, at the one loop level, the dominant new physics contributions from
extra dimensions to Z -> b,b(bar), as well as B-B(bar) and K-K(bar) mixing. We
use a model with one extra dimension containing fermions which live in four
dimensions, and gauge bosons and one scalar doublet propagating in five
dimensions. We find that the effect of the infinite tower of Kaluza-Klein modes
in Z-> b,b(bar) is finite and gives a negative correction to
R_b=Gamma_b/Gamma_h, which is used to set a lower bound of 1 TeV on the
compactification scale M_c. On the other hand, we show that the box diagrams
contributing to B-B(bar) and K-K(bar) mixing are divergent and, after proper
regularization, we find that they increase the value of the function S(x_t)
which governs this mixing. The obtained value is perfectly compatible with
available data.


title:
Next-to-next-to-leading logarithmic corrections at small transverse
  momentum in hadronic collisions

abstract:
  We study the region of small transverse momenta in qqbar- and gg-initiated
processes with no colored particle detected in the final state. We present the
universal expression of the O(alpha_s^2) logarithmically enhanced contributions
up to next-to-next-to-leading logarithmic accuracy. From there we extract the
coefficients that allow the resummation of the large logarithmic contributions.
We find that the coefficient known in the literature as B^{(2)} is process
dependent, since it receives a hard contamination from the one loop correction
to the leading order subprocess. We present the general result of B^{(2)} for
both quark and gluon channels. In particular, in the case of Higgs production,
this result will be relevant to improve the matching between resummed
predictions and fixed order calculations.


title:
The GZK Bound and Strong Neutrino-Nucleon Interactions above 10^19eV: a
  Progress Report

abstract:
  Cosmic ray events above 10^19 eV have posed a fundamental problem for more
than thirty years. Recent measurements indicate that these events do not show
the features predicted by the GZK bound. The events may, in addition, display
angular correlations with point sources. If these observations are confirmed
for point sources further than 50 - 100 Mpc, then strong interactions for the
neutrino are indicated. Recent work on extra spatial dimensions provides a
context for massive spin-2 exchanges capable of generating cross sections in
the 1 - 100 mb range, as indicated by data. Applications of extra-dimension
physics are controversial, and we comment on several contentious issues.


title: Tests of QCD: Summary of DIS 2000

abstract:
  This summary of the working group 2 of DIS 2000 encompasses experimental and
theoretical results of jet physics, open and bound state heavy flavour
production, prompt photon production, next-to-leading order QCD calculations
and beyond, instantons, fragmentation, event shapes, and power corrections,
primarily from deep-inelastic scattering and photoproduction at HERA, but also
from the LEP and Tevatron colliders.


title: Neutrino Factories: Physics

abstract:
  The recent evidence for neutrino oscillations opens a new and exciting era in
neutrino physics. The next generation of accelerator based neutrino oscillation
experiments are expected to confirm the nature of the oscillations, and begin
to measure some of the associated oscillation parameters. However, these
experiments will not be able to completely determine the mixing matrix,
determine the pattern of neutrino masses, or search for CP violation in the
lepton sector. Therefore we are motivated to consider the neutrino beams that
will be needed beyond the next generation of experiments. With this in mind the
physics case for a neutrino factory is discussed. It is shown that this new
type of neutrino source would enable the crucial questions to be addressed, and
perhaps provide enough information to discriminate between Grand Unified
Theories, or lead us to an alternative theoretical framework. It is possible
that measurements at a neutrino factory will point the way towards an
understanding of the origin of quark and lepton flavors.


title:
Top quark mass definition and top quark pair production near threshold
  at the NLC

abstract:
  We suggest an infrared-insensitive quark mass, defined by subtracting the
soft part of the quark self energy from the pole mass. We demonstrate the deep
relation of this definition with the static quark-antiquark potential. At
leading order in 1/m this mass coincides with the PS mass which is defined in a
completely different manner. Going beyond static limit, the small normalization
point introduces recoil corrections which are calculated here as well. Using
this mass concept and other concepts for the quark mass we calculate the cross
section of e+ e- -> t t-bar near threshold at NNLO accuracy adopting three
alternative approaches, namely (1) fixing the pole mass, (2) fixing the PS
mass, and (3) fixing the new mass which we call the PS-bar mass. We demonstrate
that perturbative predictions for the cross section become much more stable if
we use the PS or the PS-bar mass for the calculations. A careful analysis
suggests that the top quark mass can be extracted from a threshold scan at NLC
with an accuracy of about 100-200 MeV.


title: Discovery and Identification of W' Bosons in e gamma to nu q +X

abstract:
  We examine the sensitivity of the process e gamma to nu q +X to W' bosons
which arise in various extensions of the standard model. We consider photon
spectra from both the Weizsacker Williams process and from a backscattered
laser. The process is found to be sensitive to W' masses up to several TeV,
depending on the model, the center of mass energy, the integrated luminosity,
and assumptions regarding systematic errors. If extra gauge bosons were
discovered first in other experiments, the process could also be used to
measure W' couplings. This measurement would provide information that could be
used to unravel the underlying theory, complementary to measurements at the
Large Hadron Collider.


title: Neutrino mass, bulk majoron and neutrinoless double beta decay

abstract:
  A new economical model for neutrino masses is proposed in the context of
brane bulk scenarios for particle physics, where global B-L symmetry of the
standard model is broken spontaneously by a gauge singlet Higgs field in the
bulk. This leads to a bulk majoron whose KK excitations may make it visible if
neutrinoless double beta decay if the string scale is close to a TeV. It also
leads to neutron-anti-neutron oscillation process with transition times which
can be in the range accessible to proposed experiments.


title: $B\to \phi K$ and $B\to \phi X_s$ in the Heavy Quark Limit

abstract:
  We study $B\to \phi K$ and $B\to \phi X_s$ decays in the heavy quark limit
using perturbative QCD. The next leading order corrections introduce
substantial modifications to the naive factorization results (more than 50%).
The branching ratio $Br(B\to \phi K)$ is predicted to be in the range $(F^{B\to
K}_1(m^2_\phi)/0.33)^2(3.5\sim 4.2) \times 10^{-6}$ which is within the one
$\sigma$ allowed region from the central value of $6.2\times 10^{-6}$ measured
by CLEO, but outside the one $\sigma$ allowed region from the central value of
$17.2\times 10^{-6}$ measured by BELLE for reasonable $F_1^{B\to K}$. For the
semi-inclusive decay $B\to \phi X_s$ we also include initial bound state effect
in the heavy quark limit which decreases the branching ratio by about 10%.
$Br(B\to \phi X_s)$ is predicted to be in the range $(5.1\sim 6.3)\times
10^{-5}$.


title: Higgs Transverse Momentum at the LHC

abstract:
  Resummed QCD corrections to the transverse momentum ($Q_T$) distribution of
the Standard Model Higgs boson, produced at the CERN Large Hadron Collider, are
presented. The small $Q_T$ factorization formalism is reviewed, which is used
to extend the standard hadronic factorization theorem to the low $Q_T$ region,
with emphasis on the matching to the standard hadronic factorization.
Comparison of the $Q_T$ predictions from the extended factorization and the
parton shower method is performed.


title:
Color Dipole Systematics of the Diffraction Slope in Diffractive Photo-
  and Electroproduction of Vector Mesons

abstract:
  We present the first evaluation of the color dipole diffraction slope from
the data on diffractive photo- and electroproduction of vector mesons. The
energy and dipole size dependence of the found dipole diffraction slope are
consistent with the color dipole gBFKL dynamics.


title: Branching processes and Koenigs function

abstract:
  An explicit solution of non-critical time-homogeneous branching processes is
described.


title: Quark combinatorics and meson production ratios in hadronic Z^0 decays

abstract:
  Rich experimental data accumulated in the past few years in the hadronic
$Z^0$ decays allow one to check the quark combinatorics relations for a new
type of processes, namely: quark jets in the decays $Z^0 \to q\bar q \to
hadrons$. In this paper we review quark combinatorics rules for the yields of
vector and pseudoscalar mesons, $V/P$, in the central and fragmentation regions
of the hadronic $Z^0$ decays. It is stressed that in the central region a
direct verification of quark combinatorics rules is rather problematic because
of a considerable background related to the decay of highly excited resonances;
however such a verification is possible in the fragmentation region, at
$x_{hadron} \sim 0.5-1$, where the contribution of resonance decays is
suppressed due to the rapid decrease of spectra with increasing $x_{hadron}$.
It is shown that the experimental data in the fragmentation region for
$\rho^0/\pi^0$ and $p/\pi^+$ are in a reasonable agreement with the predictions
of quark combinatorics. The ratios of the heavy meson yields, $B^*/B$ and
  $D^*/D$, are also discussed: the data demonstrate a good agreement with the
quark combinatorial results. We analyse the structure of the suppression
parameters for strange and heavy quark productions in soft processes and
estimate their order of magnitudes in the multiperipheral processes; the ratio
$K^{\pm}/\pi^{\pm}$ at $x_{hadron}\sim 0.5-0.8$ and production probabilities of
the $c\bar c$ and $b \bar b$ mesons are in a good agreement with the estimates.


title:
An alternative: two-mixing texture for three neutrinos or three-mixing
  texture for four neutrinos

abstract:
  The alternative formulated in the title has a chance to be settled, when the
existence of the LSND effect is experimentally excluded or confirmed. The first
option, much discussed in literature, works in the case of three active
neutrinos $\nu_e, \nu_\mu, \nu_\tau$, when among their massive states $\nu_1,
\nu_2, \nu_3$ there is no direct mixing between $\nu_1$ and $\nu_3$, and the
mass hierarchy $m^2_1 < {\sim} m^2_2 \ll m^2_3$ holds. This option is
consistent with the observed deficits of solar $\nu_e$'s and atmospheric
$\nu_\mu $'s, if $\Delta m^2_{21} \leftrightarrow \Delta m^2_{\rm sol}$ and $
\Delta m^2_{32} \leftrightarrow \Delta m^2_{\rm atm}$. On the other hand, the
second option is an extension of the idea of the former to the case of four
neutrinos $\nu_s, \nu_e, \nu_\mu, \nu_\tau$ (including one sterile neutrino
$\nu_s$), when among their massive states $\nu_0, \nu_1, \nu_2, \nu_3$ there
are no direct mixings between $\nu_0$ and $nu_2$, $\nu_0$ and $\nu_3$, $\nu_1$
and $\nu_3$, and the mass hierarchy $m^2_0 < {\sim} m^2_1 \ll m^2_2 < {\sim}
m^2_3$ is now valid. Such an option, belonging to a class of textures widely
discussed in literature, may be consistent with the observed deficits of solar
$\nu_e$'s and atmospheric $\nu_\mu$'s as well as with the LSND appearance of
$\nu_e$'s in the beam of accelerator $\nu_\mu$'s, if now $\Delta m^2_{10}
\leftrightarrow \Delta m^2_{\rm sol}$, $\Delta m^2_{32} \leftrightarrow \Delta
m^2_{\rm atm}$ and $\Delta m^2_{21} \leftrightarrow \Delta m^2_{\rm LSND}$.


title:
b --> s gamma confronts B-violating scalar couplings: R-parity violating
  supersymmetry or diquark

abstract:
  We investigate the possible role that baryon number violating Yukawa
interactions may take in the inclusive decay $ B \to X_s \gamma$. The
constraints, derived using the experimental results of the CLEO collaboration,
turn out, in many cases, to be more stringent than the existing bounds.


title:
Renormalizaion group equations and infrared quasi fixed point behaviors
  of non-universal soft terms in MSSM

abstract:
  The renormalization group equations(RGEs) of non-universal soft
supersymmetric breaking terms with CP violating phases are analyzed in this
paper. We obtain the analytic solutions of RGEs by directly solving the RGEs
themselves. Compared with the method of spurion expansion our approach proves
to be simple and succinct, and easy to extend to the case of complex
parameters. With the analytical forms of the solutions we obtained the infrared
quasi fixed point behavior of soft terms are analyzed and it turns out to
support the notion in scenarios with CP violating phases.


title: Distinguishing between MSSM and NMSSM with e\gamma Scattering

abstract:
  We study the associated production of selectrons and neutralinos with
subsequent leptonic decay of the selectron in e\gamma scattering within the
framework of MSSM and NMSSM. Due to the weak couplings of singlino dominated
neutralinos, associated neutralino production e^+ + e^- -> neutralino_1 +
neutralino_2 at a linear collider can be strongly suppressed in some regions of
the parameter space. Then the process e + gamma -> selectron_{L/R} +
neutralino_{1/2} -> e + neutralino_{1/2} + neutralino_1 can give additional
informations on the underlying theory and the character of neutralino_1 and
neutralino_2.


title:
Power corrections to the process $\gamma\gamma^*\to \pi\pi$ in the
  Light-Cone Sum Rules approach

abstract:
  We applied QCD Light Cone Sum Rules to estimate power corrections to the
helicity-conserving amplitude in the process $\gamma^*\gamma\to \pi\pi$. We
found that above $Q^2 \sim 4$ GeV$^2$ power corrections are numerically small
and the twist-2 part dominates.The amplitude can be reliably calculated in this
region using models of $2 \pi$ distribution amplitudes as an input. We found
that the magnitude of the NLO corrections depends rather strongly on the
normalization of the gluonic distribution amplitude.


title: MESON2000 Conference Summary

abstract:
  This short contribution is a {\it lite} MESON2000 conference summary. As
appropriate for the 600th anniversary of the Jagellonian University, it begins
with a brief summary of the last 600 years of European history and its place in
hadron physics. Next a ``physicist chirality'' order parameter PC is
introduced. When applied to MESON2000 plenary speakers this order parameter
illustrates the separation of hadron physicists into disjoint communities. The
individual plenary talks in MESON2000 are next sorted according to the
subconference associated with each of the 36 plenary speakers. Finally, I
conclude with a previously unreported Feynman story regarding the use of models
in hadron physics.


title: The process \gamma \gamma -> \gamma \gamma, \gamma Z, ZZ

abstract:
  The Standard Model contributions to the processes $\gamma \gamma \to \gamma
\gamma$, $\gamma Z$ and ZZ at sufficiently high energies, are found to be
helicity conserving and almost purely imaginary. This is due to the W-loop
contribution, which is much bigger than the fermionic ones at such energies.
Thus the structure of these amplitudes acquires an impressive simplicity at
high energies. Nothing like this appears in other process like e.g. the the
production of a pair of neutral Higgs bosons.


title: Quark-gluon vertex in arbitrary gauge and dimension

abstract:
  One-loop off-shell contributions to the quark-gluon vertex are calculated, in
an arbitrary covariant gauge and in arbitrary space-time dimension, including
quark-mass effects. It is shown how one can get results for all on-shell limits
of interest directly from the off-shell expressions. In order to demonstrate
that the Ward-Slavnov-Taylor identity for the quark-gluon vertex is satisfied,
we have also calculated the corresponding one-loop contribution involving the
quark-quark-ghost-ghost vertex.


title: Testing Left-Right Symmetric Gauge Theories at e^+e^- Colliders

abstract:
  If the Standard Model is embedded in a left-right symmetric gauge theory at
the TeV scale, the pair production of light W-bosons in e^+e^- collisions,
e^+e^- -> W^+W^-, will be affected by mixings in the gauge and neutrino
sectors, and by the t-channel exchange of a heavy right-handed neutrino. The
modification of the cross section by these new effects is studied for
high--energy e^+e^- colliders.


title: Next-Order Estimate of Higgs to Two-Gluon Rate

abstract:
  Using asymptotic Pade approximant methods, we have calculated the
O(alpha_s^5) contribution to the Standard-Model H to gg decay rate. This
process is of particular interest because of the slow convergence evident from
the known terms of its QCD series. The O(alpha_s^5) term is expressed as a 3rd
degree polynomial in $L= log (\frac{\mu^2}{m_t^2(\mu)})$. We find that the
asymptotic Pade predictions for the renormalization-group accessible
coefficients of L, L^2 and L^3 are within 1%, 2% and 7% of their respective
values. The inclusion of the O(alpha_s^5) contribution renders the full decay
rate virtually scale independent over the entire 0.3 M_H < mu < M_t range of
the renormalization scale mu.


title: The many sources effect on the genuine multihadron correlations

abstract:
  Here we report on a study aimed to explore the dependence of the genuine
multiparticle correlations on the number of sources while the influence of
other possible factors affecting the multihadron production is avoided. The
analysis utilised the normalised cumulants, calculated in three-dimensional
phase space, of the reaction e+e- -> Z -> hadrons using a large Monte Carlo
event sample. The multi-sources reactions were simulated by overlaying a few
independent single e+e- annihilation events. It was found that as the number of
sources S increases, the cumulants do not change significantly their structure,
but those of an order q>2 (i.e. more than 2 pions) decrease fast in their
magnitude. This reduction can be understood in termsof combinatorial
considerations of source mixing which dilutes the correlations by a factor of
about 1/S^{q-1} which can also serve as a method to estimated the number of
sources. This expected suppression is well reproduced by recent cumulant
measurements in hadron and nucleus induced reactions both in one (rapidity) and
two (rapidity vs. azimuthal angle) dimensions. The diminishing genuine
correlations effect should also appear in other dynamical correlations like the
Bose-Einstein in e+e- -> W+W- -> hadrons and in nucleus-nucleus reactions.


title:
Reducing the Theoretical Uncertainty in Extracting |V_{ub}| from the
  Inclusive Semileptonic b to u Decay Rate

abstract:
  Utilizing asymptotic Pade-approximant methods, we estimate the three-loop
order MS-bar coefficients of alpha_s^3[\log(\mu^2/m^2_b(\mu)]^k terms [k =
{0,1,2,3}] within the $b \to u\ell^-\bar{\nu}_\ell$ decay rate. Except for the
coefficient of the k = 0 term, all other coefficients may also be obtained via
renormalization-group (RG) methods. The relative errors in asymptotic
Pade-approximant estimates of the k = {1,2,3} terms are found to be 5.1% or
less, thereby providing an estimate of the theoretical uncertainty in the
asymptotic Pade-approximant estimate of the RG-inaccessible k = 0 term. By a
judicious choice in the renormalization scale parameter, we are able to extract
|V_{ub}| from the inclusive decay rate to within 7% theoretical uncertainty.


title:
Chiral Ward identities and pion propagation at finite temperature in the
  linear sigma model

abstract:
  Working within the linear sigma model at finite temperature, we construct
effective one-loop vertices and propagators satisfying the chiral Ward
identities, for small pion momentum and mass compared to the sigma mass. We
obtain an expansion for the pion dispersion relation up to second order in the
parameter m_pi^2/4pi^2f_pi^2. At leading order, this expansion reproduces the
dispersion curve obtained in chiral perturbation theory. We also study pion
damping and compute the mean free path for pions traveling in the medium before
forming a sigma resonance. These results are also in good agreement with chiral
perturbation theory when using a value for the sigma mass of 600 MeV.


title: Bottom-up model for maximal $\nu_{\mu} - \nu_{\tau}$ mixing

abstract:
  We construct a model which provides maximal mixing between a pseudo-Dirac
$\nu_{\mu}/\nu_{\tau}$ pair, based on a local $U(1)_{L_{\mu}-L_{\tau}}$
symmetry. Its strengths, weaknesses and phenomenological consequences are
examined. The mass gap necessitated by the pseudo-Dirac structure is most
naturally associated with the LSND anomaly. The solar neutrino problem then
requires a light mirror or sterile neutrino. By paying a fine-tuning price to
nullify the mass gap, one can also invoke $\nu_e \to \nu_{\mu,\tau}$ for the
solar problem. The model predicts a new intermediate range force mediated by
the light gauge boson of $U(1)_{L_{\mu}-L_{\tau}}$. Through the mixing of
$\mu$, $\tau$ and $e$, this force couples to electrons and thus may be searched
for in precision ``gravity'' experiments.


title: Effects of Instantons on the YN Interaction

abstract:
  We investigate the symmetric and anti-symmetric spin-orbit forces (SLS and
ALS) of the effective $\Lambda$N interaction derived from a quark cluster model
with the instanton-induced interaction (\III), which can reproduce the observed
YN cross sections as well as the observed NN scattering data.
  It is found that coupling to the $\Sigma$N channel enhances $\Lambda$N ALS,
and therefore that the cancellation between SLS and ALS in the $\Lambda$N
channel becomes more complete. This may be one of the major reasons why the
single-particle spin-orbit force of $\Lambda$ in nuclei is weak.


title:
The seesaw mechanism at arbitrary order: disentangling the small scale
  from the large scale

abstract:
  We develop a recipe which allows one to recursively and uniquely decouple the
large scale from the small scale in mass matrices of the seesaw type, up to any
order in the inverse of the large scale. Our method allows one to calculate the
mass matrix of the light neutrinos with arbitrary precision. The same method
can be applied in the case of quark mass matrices in an extension of the
Standard Model with vector-like quarks which have mass terms at a scale much
higher than the electroweak scale.


title: Kinematic Effects in Quarkonia Production

abstract:
  We investigate energy (momentum) distributions in J/Psi photoproduction and
J/Psi production in B meson decay. In particular the upper endpoint region of
the spectrum is examined where the effect of soft gluon emission from the ccbar
pair becomes important. Constructing a model which is consistent with the
so-called shape function formalism we consider these fragmentation effects and
show that the relevance of possible colour octet contributions in the
photoproduction channel is still inconclusive.


title: Towards an understanding of isospin violation in pion-nucleon scattering

abstract:
  We investigate isospin breaking in low-energy pion-nucleon scattering in the
framework of chiral perturbation theory. This work extends the systematic
analysis of [1] to the energy range above threshold. Various relations, which
identically vanish in the limit of isospin symmetry, are used to quantify
isospin breaking effects. We study the energy dependence of the S- and P-wave
projections of these ratios and find dramatic effects in the S-waves of those
two relations which are given in terms of isoscalar quantities only. This
effect drops rather quickly with growing center-of-mass energy.


title:
A superformula for neutrinoless double beta decay II: The short range
  part

abstract:
  A general Lorentz-invariant parameterization for the short-range part of the
0vBB decay rate is derived. Combined with the long range part already published
this general parameterization in terms of effective B-L violating couplings
allows one to extract the 0vBB limits on arbitrary lepton number violating
theories.


title:
Yukawa Unification as a Window into the Soft Supersymmetry Breaking
  Lagrangian

abstract:
  We study Yukawa unification, including the effects of a physical neutrino
mass consistent with the Superkamiokande observations, in a string/$D$-brane
inspired Pati-Salam model which allows the most general non-universal scalar
and gaugino masses, including the usual $D$-term contributions which arise in
SO(10). We investigate how the tight constraints from rare decays such as $b
\to s \gamma$ and $\tau \to \mu \gamma$ can provide information about the
family dependent supersymmetry breaking soft Lagrangian, for example the
trilinears associated with the second and third family. Many of our results
also apply to SO(10) to which the model approximately reduces in a limiting
case. In both models we find that Yukawa unification is perfectly viable
providing the non-universal soft masses have particular patterns. In this sense
Yukawa unification acts as a window into the soft supersymmetry breaking
Lagrangian.


title:
Universality of non-leading logarithmic contributions in
  transverse-momentum distributions

abstract:
  We consider the resummation of the logarithmic contributions to the region of
small transverse momenta in the distributions of high-mass systems (lepton
pairs, vector bosons, Higgs particles, ....) produced in hadron collisions. We
point out that the resummation formulae that are usually used to compute the
distributions in perturbative QCD involve process-dependent form factors and
coefficient functions. We present a new universal form of the resummed
distribution, in which the dependence on the process is embodied in a single
perturbative factor. The new form simplifies the calculation of non-leading
logarithms at higher perturbative orders. It can also be useful to
systematically implement process-independent non-perturbative effects in
transverse-momentum distributions. We also comment on the dependence of these
distributions on the factorization and renormalization scales.


title:
Effects of $\Sigma$N channels on the Spin-Orbit Force in
  $\Lambda$-hypernuclei

abstract:
  Effects of the $\Sigma$N channels on the spin-orbit force in
$\Lambda$-hypernuclei are investigated. It is found that the cancellation
between the symmetric and the antisymmetric $\Lambda$N spin-orbit force becomes
more complete when the contribution from the $\Sigma$N channels is included.
This may be the one of the reasons why the observed LS splitting of the
$\Lambda$ single particle energy is very small.


title: Lambda polarization from unpolarized quark fragmentation

abstract:
  The longstanding problem of explaining the observed polarization of Lambda
hyperons inclusively produced in the high energy collisions of unpolarized
hadrons is tackled by considering spin and k_T dependent quark fragmentation
functions. The data on Lambda's and Lambda-bar's produced in p-N processes are
used to determine simple phenomenological expressions for these new "polarizing
fragmentation functions", which describe the experiments remarkably well.


title: On the two kinds of vector particles

abstract:
  All known elementary vector particles, the photon, Z, W and the gluons, are
described by the gauge theory. They belong to the real representation (1/2,1/2)
of the Lorentz group. On the other hand inequivalent representations (1,0) and
(0,1) also correspond to particles with spin 1. It is natural to suppose that,
along with the known vector particles, the new particles can exist. Evidence
for the existence of these particles in nature is the presence of the
axial-vector meson resonances with quantum numbers 1^{+-}. Other indications
for their existence are discussed. The signatures of their contributions into
different physical processes are presented.


title: Chiral loops and a_0(980) exchange in \phi->\pi^0\eta\gamma

abstract:
  The radiative $\phi\to\pi^0\eta\gamma$ decay is discussed emphasizing the
effects of the $a_0$(980) scalar resonance which dominates the high values of
the $\pi^0\eta$ invariant mass spectrum. In its lowest part, the proposed
amplitude coincides with the reliable and ChPT-inspired contribution coming
from chiral loops. The $a_0$(980) resonance is then incorporated exploiting the
complementarity between ChPT and the linear sigma model for this channel. The
recently reported experimental invariant mass distribution and branching ratio
can be satisfactorily accommodated in our framework. For the latter, a value of
$B(\phi\to\pi^0\eta\gamma)$ in the range $(0.75$--$0.95)\times 10^{-4}$ is
predicted.


title: Studying the Top Quark

abstract:
  The top quark, discovered at the Fermilab Tevatron collider in 1995, is the
heaviest known elementary particle. Its large mass suggests that it may play a
special role in nature. It behaves differently from the other known quarks due
both to its large mass and its short lifetime. Thus far we have only crude
measurements of the properties of the top quark, such as its mass, weak
interactions, strong interactions, and decay modes. These measurements will be
made more precise when the Tevatron begins operation again in 2001. I review
the present status of these measurements, and discuss their anticipated
improvement.


title:
The Supersymmetry Soft-breaking Lagrangian - Where Experiment and String
  Theory Meet

abstract:
  After an introduction recalling that we expect low energy supersymmetry to be
part of our description of nature because of considerable indirect evidence and
successful predictions, and a discussion of the essential role of data for
formulating and testing string theory, these lectures focus on the role of the
supersymmetry soft-breaking Lagrangian in connecting experiment and string
theory. How to measure tan$\beta$ and the soft parameters is examined via a
number of applications, and the difficulty of measuring tan$\beta$ at hadron
colliders is explained. In each case the important role of soft phases is made
explicit, and the true number of parameters is counted. Applications include
the chargino and neutralino sectors, the Higgs sector and how its results
change when phases are included, measuring the (relative) gluino phase, CP
violation in K and B systems and whether all CP violation can be due to soft
phases, how to learn if the LSP is the cold dark matter of the universe, and
baryogenesis. It is emphasized that the success of supersymmetry in explaining
the breaking of electroweak symmetry is probably its most important
achievement, and implications of that explanation for superpartner masses are
shown. Combining many of these considerations, a further application argues
that a lepton collider of total energy 600 GeV with a polarized beam is one we
can be confident will do important physics even after LHC. The question of the
origins of CP violation, whether the CKM phase can be zero, and the possibility
that the soft phases can tell us about compactification and supersymmetry
breaking are discussed. Some of the applications and issues are examined in a
D-brane based model that can describe the usual collider and dark matter
phenomenology, and includes phases and CP violation as well.


title: Multivariate Fitting and the Error Matrix in Global Analysis of Data

abstract:
  When a large body of data from diverse experiments is analyzed using a
theoretical model with many parameters, the standard error matrix method and
the general tools for evaluating errors may become inadequate. We present an
iterative method that significantly improves the reliability of the error
matrix calculation. To obtain even better estimates of the uncertainties on
predictions of physical observables, we also present a Lagrange multiplier
method that explores the entire parameter space and avoids the linear
approximations assumed in conventional error propagation calculations. These
methods are illustrated by an example from the global analysis of parton
distribution functions.


title: Light Axion within the Next-to-Minimal Supersymmetric Standard Model

abstract:
  We analyze the Higgs sector in the Next-to-Minimal Supersymmetric Standard
Model, emphasizing the possibility of a light CP-odd scalar (axion) in the
spectrum. We compute the coupling of the Standard-Model-like Higgs boson to a
pair of axions, and show that it can be large enough to modify the Higgs
branching fractions, with a significant impact on the Higgs searches. We
delineate the range of parameters relevant for this scenario, and also derive
analytic expressions for the scalar masses and couplings in two special cases -
a decoupling limit where all scalars other than the axion are heavier than the
Standard-Model-like Higgs boson, and the large tan beta limit.


title:
Testing Neutrino Properties at Long Baseline Experiments and Neutrino
  Factories

abstract:
  It is shown that explanations of atmospheric neutrino anomaly other than
$\nu_\mu - \nu_\tau oscillations (e.g. decay, decoherence and $\nu_\mu -
\nu_\tau - \nu_{KK}$ mixing) can be tested at future facilities. Stringent
tests of CPT invariance in neutrino oscillations can also be performed.


title: Progress in Perturbative Color Transparency

abstract:
  A brief overview of the status of color transparency experiments is
presented. We report on the first complete calculations of color transparency
within a perturbative QCD framework. We also comment on the underlying
factorization method and assumptions. Detailed calculations show that the slope
of the transparency ratio with $Q^2$, and the effective attenuation cross
sections extracted from color transparency experiments depend on the $x$
distribuition of wave functions.


title:
D and J/psi production from deconfined matter in relativistic heavy ion
  collisions

abstract:
  We study the production of the D and J/psi mesons from deconfined quark
matter at CERN SPS energy. Using the MICOR microscopical coalescence model we
determine the transverse momentum spectra of these charm mesons. We predict the
slopes of their transverse momentum spectra in Pb+Pb collision at 158
GeV/nucleon beam energy.


title: Pairs of charged heavy-leptons from an SU(3) X U(1) model at CERN LHC

abstract:
  One of the versions of the SU(3)$_L\otimesU(1)_N$ electroweak model predicts
charged heavy-leptons which do not belong to any class of heavy-leptons
proposed up to now. We investigate the production and signatures of pairs of
these heavy-leptons {\it via} the Drell-Yan process and the gluon-gluon fusion
at the CERN Large Hadron Collider (LHC). As an example we study the decay of
the exotic leptons into another ones. We see that the lifetime of the exotic
leptons can be short.


title:
The implementation of the four-jet matrix elements in HERWIG and
  elsewhere

abstract:
  The new version 6.1 of the HERWIG event generator allows one to simulate
hadronic final states in electron-positron annihilations using the
$O(\alpha_s^2)$ partonic matrix elements (MEs) for $e^+e^-\to q\bar qgg$ and
$e^+e^-\to q\bar q Q\bar Q$. The consequent phenomenology is discussed in the
case of four-jet signatures of particular relevance to future electron-positron
Linear Colliders (LCs), such as in Higgs boson searches. The new approach
adopted in HERWIG is compared to the standard $O(\alpha_s)$ description, as
well as to other recently presented event generators also based on $e^+e^-\to4$
parton MEs.


title:
Charged Higgs Contribution into (t b_bar)-pair Production in Hadronic
  Collisions

abstract:
  We investigate the charged Higgs boson contribution into $t\bar b$-pair
production in pp-collisions at LHC. It is shown that due to the $\cz$-boson
exchange the total yield of $t\bar b$ is modified significantly for small and
large values of $\tan\beta$. However, for the small values of $\tan\beta$ one
should expect also the production of right-polarized top quark contrary to pure
left-polarized t-quark production through $W^{\pm}$-boson exchange only. This
fact provides a possibility to separate $H^{\pm}$ and $W^{\pm}$ contributions
by means of the investigations of angular distributions of top decay products.
The detailed simulation of the signal and relevant background processes is
performed.


title:
Transverse Muon Polarization in $K^{\pm}\to\pi^0\mu^{\pm}\nu$ Decay
  Induced by the Two-Photon Final-State Interaction

abstract:
  We calculate the transverse muon polarization in the decay
$K^{\pm}\to\pi^0\mu^{\pm}\nu$ induced by the electromagnetic two-photon
final-state interaction. For the central part of the Dalitz plot the typical
value of this polarization is about $4\times 10^{-6}$.


title: Hard and soft QCD in charmonium production

abstract:
  We show that both hard perturbative and soft non-perturbative QCD effects are
important in hadroproduction of charmonium. Observed $x_F$ and $p_\perp$
distributions of J/psi in fixed target experiments can be well described by our
Monte Carlo model based on perturbative QCD and the Color Evaporation Model.


title:
Neutral heavy lepton production at next high energy $e^+e^-$ linear
  colliders

abstract:
  The discovery potential for detecting new heavy Majorana and Dirac neutrinos
at some recently proposed high energy $e^+e^-$ colliders is discussed. These
new particles are suggested by grand unified theories and superstring-inspired
models. For these models the production of a single heavy neutrino is shown to
be more relevant than pair production when comparing cross sections and
neutrino mass ranges.
  The process $ e^+e^- \longrightarrow {\nu} e^{\pm} W^{\mp}$ is calculated
including on-shell and off-shell heavy neutrino effects.
  We present a detailed study of cross sections and distributions that shows a
clear separation between the signal and standard model contributions, even
after including hadronization effects.


title: One-loop results for the quark-gluon vertex in arbitrary dimension

abstract:
  Results on the one-loop quark-gluon vertex with massive quarks are reviewed,
in an arbitrary covariant gauge and in arbitrary space-time dimension. We show
how it is possible to get on-shell results from the general off-shell
expressions. The corresponding Ward-Slavnov-Taylor identity is discussed.


title: Consequences of a Z_2 Symmetry for Neutrino Oscillation

abstract:
  A $Z_{2L}\times Z_{2R}$ generation symmetry in the neutrino sector predicts
the atmospheric neutrino mixing to be maximal, and the MNS matrix element
$U_{e3}$ to be zero, consistent with observations. Solar neutrino mixing may be
maximal but is not required by the symmetry. Neutrino masses of the first two
generations are predicted to vanish, providing a first approximation to the
oscillation data. The consequence of a smaller $Z_2$ symmetry is also
discussed. In that case, deviation from the $Z_{2L}\times Z_{2R}$ result is of
the order of the neutrino mass ratio between the first two generations and the
third generation.


title: Grand Unification Signal from Ultra High Energy Cosmic Rays?

abstract:
  The spectrum of ultrahigh energy (above \approx 10^{9} GeV) cosmic rays is
consistent with the decay of GUT scale particles. The predicted mass is
m_X=10^b GeV, where b=14.6_{-1.7}^{+1.6}.


title: Natural Quintessence?

abstract:
  We formulate conditions for the naturalness of cosmological quintessence
scenarios. The quintessence lagrangian is taken to be the sum of a simple
exponential potential and a non-canonical kinetic term. This parameterization
covers most variants of quintessence and makes the naturalness conditions
particularly transparent. Several ``natural'' scalar models lead, for the
present cosmological era, to a large fraction of homogeneous dark energy
density and an acceleration of the scale factor as suggested by observation.


title: QCD in a Finite Volume

abstract:
  We will review our understanding of non-abelian gauge theories in finite
physical volumes. It allows one in a reliable way to trace some of the
non-perturbative dynamics. The role of gauge fixing ambiguities related to
large field fluctuations is an important lesson that can be learned. The
hamiltonian formalism is the main tool, partly because semiclassical techniques
are simply inadequate once the coupling becomes strong. Using periodic boundary
conditions, continuum results can be compared to those on the lattice. Results
in a spherical finite volume will be discussed as well.


title: A chiral crystal in cold QCD matter at intermediate densities?

abstract:
  The analogue of Overhauser (particle-hole) pairing in electronic systems
(spin-density waves with non-zero total momentum $Q$) is analyzed in
finite-density QCD for 3 colors and 2 flavors, and compared to the
color-superconducting BCS ground state (particle-particle pairing, $Q$=0). The
calculations are based on effective nonperturbative four-fermion interactions
acting in both the scalar diquark as well as the scalar-isoscalar quark-hole
('$\sigma$') channel. Within the Nambu-Gorkov formalism we set up the coupled
channel problem including multiple chiral density wave formation, and evaluate
the resulting gaps and free energies. Employing medium-modified
instanton-induced 't Hooft interactions, as applicable around $\mu_q\simeq 0.4$
GeV (or 4 times nuclear saturation density), we find the 'chiral crystal phase'
to be competitive with the color superconductor.


title: Crystalline Color Superconductivity

abstract:
  In any context in which color superconductivity arises in nature, it is
likely to involve pairing between species of quarks with differing chemical
potentials. For suitable values of the differences between chemical potentials,
Cooper pairs with nonzero total momentum are favored, as was first realized by
Larkin, Ovchinnikov, Fulde and Ferrell (LOFF). Condensates of this sort
spontaneously break translational and rotational invariance, leading to gaps
which vary periodically in a crystalline pattern. Unlike the original LOFF
state, these crystalline quark matter condensates include both spin zero and
spin one Cooper pairs. We explore the range of parameters for which crystalline
color superconductivity arises in the QCD phase diagram. If in some shell
within the quark matter core of a neutron star (or within a strange quark star)
the quark number densities are such that crystalline color superconductivity
arises, rotational vortices may be pinned in this shell, making it a locus for
glitch phenomena.

categories: hep-ph astro-ph cond-mat.supr-con nucl-th


title:
Neutrinos in Extra Dimensions and the Anomalous Magnetic Moments of
  Leptons

abstract:
  The use of extra dimensional scenarios as models for neutrino mass affects
many low energy observables. We consider the implications of virtual bulk
neutrinos in precision experiments of the anomalous magnetic moments of the
muon and the electron. We consider neutrino models in factorizable geometry of
the type M_4 x T as well as the sliced AdS_5 non-factorizable geometry. In both
geometries we find finite contributions to g-2 after summing over the KK
excitations of the bulk neutrinos. In the case of Randall-Sundrum geometry, we
find that the muon experiment is approaching the precision necessary to probe
these models.


title: Looking for Novel CP-Violating Effects in B->K^*l^+l^-

abstract:
  The CP-violating asymmetries in the exclusive decay B->K^*l^+l^- (l=e,mu,tau)
are predicted to be exceedingly small in the standard model (SM), thereby
offering an opportunity to assess various new-physics scenarios. We derive
quantitative predictions for various integrated observables in B->K^*mu^+mu^-
decay in the presence of physics beyond the SM with additional CP phases and an
extended operator basis. In particular, a model-independent analysis of CP
asymmetries that require the presence of unitarity phases, in addition to CP
violation, is performed. We find that in the low dimuon invariant mass region
2m_mu<M_{mu^+mu^-}<M_{J/psi}, the CP asymmetries are highly suppressed by small
dynamical phases, assuming that new physics is unlikely to significantly alter
the Wilson coefficients of the operators governing two-body hadronic B decays.
Taking into account current experimental data on the measured b->s gamma rate
and the upper limit on BR(B^0->K^{*0}mu^+mu^-), CP-violating effects of a few
per cent are estimated, even in the presence of new physics with CP phases of
O(1). By contrast, in the high dimuon invariant mass region
M_{psi'}<M_{mu^+mu^-}<(M_B-M_{K^*}) significant CP-violating effects are
possible. Given a branching ratio of 1.8 x 10^{-6}, the CP asymmetries can be
quite substantial (\sim 20% or more), and thus may serve as a means of
discovering physics transcending the SM.


title: Active-Sterile Neutrino Transformation and r-Process Nucleosynthesis

abstract:
  The type II supernova is considered as a candidate site for the production of
heavy elements. Since the supernova produces an intense neutrino flux, neutrino
scattering processes will impact element formation. We examine active-sterile
neutrino conversion in this environment and find that it may help to produce
the requisite neutron-to-seed ratio for synthesis of the r-process elements.


title: QCD Glueball Regge Trajectories and the Pomeron

abstract:
  We report a glueball Regge trajectory emerging from diagonalizing a confining
Coulomb gauge Hamiltonian for constituent gluons. Using a BCS vacuum ansatz and
gap equation, the dressed gluons acquire a mass, of order 800 $MeV$, providing
the quasiparticle degrees of freedom for a TDA glueball formulation. The TDA
eigenstates for two constituent gluons have orbital, $L$, excitations with a
characteristic energy of 400 $MeV$ revealing a clear Regge trajectory for
$\vec{J} = \vec{L} + \vec{S}$, where $S$ is the total (sum) gluon spin.
Significantly, the $S = 2$ glueball spectrum coincides with the Pomeron given
by $\alpha_P(t)=1.08+0.25 t $. Finally, we also ascertain that lattice data
supports our result, yielding an average intercept of 1.1 in good agreement
with the Pomeron.


title: Anomalous U(1)_A and Electroweak Symmetry Breaking

abstract:
  We suggest a new mechanism for electroweak symmetry breaking in the
supersymmetric Standard Model. Our suggestion is based on the presence of an
anomalous U(1)_A gauge symmetry, which naturally arises in the four dimensional
superstring theory, and heavily relies on the value of the corresponding
Fayet-Illiopoulos \xi-term.


title: DVCS amplitude with kinematical twist-3 terms

abstract:
  We compute the amplitude of deeply virtual Compton scattering (DVCS) using
the calculus of QCD string operators in coordinate representation. To restore
the electromagnetic gauge invariance
  (transversality) of the twist-2 amplitude we include the operators of twist-3
which appear as total derivatives of twist-2 operators. Our results are
equivalent to a Wandzura-Wilczek approximation for twist-3 skewed parton
distributions. We find that this approximation gives a finite result for the
amplitude of a longitudinally polarized virtual photon, while the amplitude for
transverse polarization is divergent, i.e., factorization breaks down in this
term. However, the divergent part has zero projection onto the polarization
vector of the final real photon.


title:
Discovery of a new particle named a coretron and a non-baryionic dark
  matter

abstract:
  %auto-ignore This paper has been withdrawn by the author(s) since somebody do
not agree with my idea.


title:
QCD Factorization For B Decays To Two Light Pseudoscalars Including
  Chirally Enhanced Corrections

abstract:
  Since b quark mass is not asymptotically large, chirally enhanced corrections
which arise from twist-3 wave functions may be important in B decays. We thus
evaluate the hadronic matrix elements with the emitted meson described by
leading twist and twist-3 distribution amplitudes $\Phi_p(x)$. After summing
over the four "vertex correction" diagrams, we obtain the results with infrared
finiteness which shows that chirally enhanced corrections arise from
$\Phi_p(x)$ can be consistently included in QCD factorization. We also briefly
discuss the contributions from "hard spectator" diagrams.


title: Intermediate mass strangelets are positively charged

abstract:
  For a limited range of parameters, stable strange quark matter may be
negatively charged in bulk due to one gluon exchange interactions. However, the
reduction in strange quark occupation in the surface layer, which is
responsible for surface tension, more than compensates this for intermediate
mass strangelets, which therefore always have positive quark charge (e.g. for
baryon number between 10^2 and 10^{18} assuming alpha_S=0.9). While details are
sensitive to the choice of renormalisation, the general conclusion is not. This
rules out a scenario where negatively charged strangelets produced in
ultrarelativistic heavy ion colliders might grow indefinitely with potentially
disastrous consequences.


title: Van Hove Singularities in the Quark-Gluon Plasma

abstract:
  General arguments as well as different approximations for the in-medium quark
propagator in a quark-gluon plasma lead to quark dispersion relations that
exhibit a minimum in one branch (plasmino). This minimum causes Van Hove
singularities in the dilepton production rate and mesonic correlators, which
might have observable consequences.


title: Rotating relativistic superfluid

abstract:
  Relativistic equation of state and velocity comparable with the speed of
light are included in consideration of a superfluid rotating in a cylindrical
container. Minimizing the free energy, we derive the equation of motion. It
admits an analytic solution, the solid-body rotation inside and irrotational
motion near the walls of the vessel, providing the vortex quantum is not
extremely high with respect to the particle rest mass that is satisfied for
real astrophysical objects. The relativistic velocity of the vessel and the
relativistic equation of state results to the deviation of the angular velocity
of the solid-body motion inside and that of the vessel. The boundary between
the solid-body and irrotational motion is also shifted sufficiently leading to
a difference between the total angular momentum of superfluid and the normal
matter.


title:
A Relativistic Quark Model for Mesons with an Instanton-Induced
  Interaction

abstract:
  We present new results of a relativistic quark model based on the
Bethe-Salpeter equation in its instantaneous approximation. Assuming a linearly
rising confinement potential with an appropriate spinorial structure in Dirac
space and adopting a residual interaction based on instanton effects, we can
compute masses of the light mesons up to highest observed angular momenta with
a natural solution of the $U_A(1)$ problem. The calculated ground states masses
and the radial excitations describe the experimental results well. In this
paper, we will also discuss our results concerning numerous meson decay
properties. For processes like $\pi^+/K^+\to e^+\nu_e\gamma$ and
$0^-\to\gamma\gamma$ at various photon virtualities, we find a good agreement
with experimental data. We will also comment on the form factors of the
$K_{\ell 3}$ decay and on the decay constants of the $\pi$, $K$ and $\eta$
mesons. For the sake of completeness, we will furthermore present the
electromagnetic form factors of the charged $\pi$ and $K$ mesons as well as a
comparison of the radiative meson decay widths with the most recent
experimental data.


title: The Meson Spectrum in a Covariant Quark Model

abstract:
  Within the framework of the instantaneous Bethe-Salpeter equation, we present
a detailed analysis of light meson spectra with respect to various
parameterizations of confinement in Dirac space. Assuming a linearly rising
quark-antiquark potential, we investigate two different spinorial forms (Dirac
structures), namely ${1/2}(\Id\otimes\Id - \gamma^0\otimes\gamma^0)$ as well as
the $U_A(1)$-invariant combination ${1/2}(\Id\otimes\Id -
\gamma^5\otimes\gamma^5 - \gamma^\mu\otimes\gamma_\mu)$, both providing a good
description of the ground state Regge trajectories up to highest observed
angular momenta. Whereas the first structure is slightly prefered concerning
numerous meson decay properties (see \cite{pap41}), we find the
$U_A(1)$-invariant force to be much more appropriate for the description of a
multitude of higher mass resonances discovered in the data of the {\sc Crystal
Barrel} collaboration during the last few years. Furthermore, this confinement
structure has the remarkable feature to yield a linear dependence of masses on
their radial excitation number. For many experimental resonances such a
trajectory-like behaviour was observed by Anisovich {\it et al.} We can confirm
that almost the same slope occurs for all trajectories. Adding the
$U_A(1)$-breaking instanton induced 't Hooft interaction we can compute the
pseudoscalar mass splittings with both Dirac structures and for the scalar
mesons a natural mechanism of flavour mixing is achieved. [...]


title:
Conventional Beams or Neutrino Factories: The Next Generation of
  Accelerator-Based Neutrino Experiments

abstract:
  The purpose of this paper is to provoke a discussion about the right next
step in accelerator-based neutrino physics. In the next five years many
experiments will be done to determine the neutrino mixing parameters. However,
the small parameters $\theta_{13}\Delta m_{21}^2$, and the CP violating phase
are unlikely to be well determined. Here, I look at the potential of
high-intensity, low-energy, narrow-band conventional neutrino beams to
determine these parameters. I find, after roughly estimating the possible
intensity and purity of conventional neutrino and anti-neutrino beam, that
$\sin^2\theta_{13}$ can be measured if greater than a few parts in ten
thousand, $\Delta m_{21}^2$ can be measured if it is greater than $4\times
10^{-5}$ (eV)$^2$, and the CP violating phase can be measured if it is greater
than 20$^\circ$ and the other parameters are not at their lower bounds. If
these conclusions stand up to more detailed analysis, these experiments can be
done long before a muon storage ring source could be built, and at much less
cost.


title: Self-Interacting Dark Matter from the Hidden Heterotic-String Sector

abstract:
  It has been suggested recently that self-interacting dark matter fits better
the observational characteristics of galaxy dynamics. We propose that the
self-interacting dark matter is composed from the glueballs of the hidden
sector non-Abelian gauge group, while the hidden matter states exist in
vector-like representation and decouple from the light spectrum. It is shown
that these glueballs are semi-stable with the life-time larger than the present
age of the Universe, if their mass is 1 GeV or less. The constraint on their
abundance today suggests that the energy was stored in the hidden sector soon
after inflation. This imposes an upper limit on the reheating temperature. We
further study the naturalness of this scenario in the context of the
free-fermionic string models and point out a class of such models where the
self-interacting dark matter from the hidden sector is indeed plausible.


title: Color transparency in deeply inelastic diffraction

abstract:
  We suggest a simple physical picture for the diffractive parton distributions
that appear in diffractive deeply inelastic scattering. In this picture,
partons impinging on the proton can have any transverse separation, but only
when the separation is small can they penetrate the proton without breaking it
up. By comparing the predictions from this picture with the diffractive data
from HERA, we determine rough values for the small separations that dominate
the diffraction process.


title: Contribution of sigma meson pole to K_L-K_S mass difference

abstract:
  The hypothesis of sigma meson pole dominance in the Delta I = 1/2 K -> pi pi
amplitudes is tested by using the K_L-K_S mass difference.


title: Lessons from Recent Measurements of CP Violation

abstract:
  We review various implications of recent experimental results concerning CP
violation and mixing in $K\to\pi\pi$, $B\to\psi K_S$, $D\to K\pi$ and $D\to KK$
decays.


title: The g Factor of a Bound Electron in a Hydrogen-Like Atom

abstract:
  Recently, a precise measurement on the bound electron g factor in
hydrogen-like carbon was performed [1]. We consider the present status of the
theory of the g factor of an electron bound in a hydrogen-like atom and discuss
new opportunities and possible applications of the recent experiment.


title: LHC Signature of the Minimal SUGRA Model with a Large Soft Scalar Mass

abstract:
  Thanks to the focus point phenomenon, it is quite {\it natural} for the
minimal SUGRA model to have a large soft scalar mass m_0 > 1 TeV. A distinctive
feature of this model is an inverted hierarchy, where the lighter stop has a
significantly smaller mass than the other squarks and sleptons. Consequently,
the gluino is predicted to decay dominantly via stop exchange into a channel
containing 2b and 2W along with the LSP. We exploit this feature to construct a
robust signature for this model at the LHC in leptonic channels with 3-4 b-tags
and a large missing-E_T.


title: Gribov's Confinement Scenario

abstract:
  I give a brief account of Gribov's scenario of supercritical charges in QCD.
Gribov's equation for the Green function of light quarks and its derivation
from the corresponding Dyson-Schwinger equation are described. The resulting
Green function is shown to exhibit chiral symmetry breaking.


title: Asymmetry in Charmed Particles Production in $\Sigma^{-}$ beam

abstract:
  We present the calculation of the inclusive $x_F$-distributions of charmed
hadrons, produced in high-energy $\Sigma^-$-beam. The calculation is based on
the modified mechanism of charmed quarks fragmentation as well as on the
mechanism of $c$-quark recombination with the valence quarks from initial
hadrons. We predict the additional asymmetry in the production of charmed
hadrons due to the different distributions of the valence s and d quarks in
$\Sigma^-$-beam.


title: Single neutral heavy lepton production at electron-muon colliders

abstract:
  New heavy Majorana and Dirac neutrinos production at future electron-muon
colliders are investigated. The production of a single heavy neutrino is shown
to be more relevant than pair production when comparing cross sections and
neutrino mass ranges. The process $e^\pm \mu^\mp \longrightarrow {\nu}
\ell^{\pm} W^{\mp}$ is studied including on-shell and off-shell heavy neutrino
effects. Distributions are calculated including hadronization effects and
experimental cuts that suppress background, in order to have a clear signal for
heavy neutral leptons.


title: Origin of neutrino masses and mixings

abstract:
  A brief overview of the important theoretical issues in neutrino physics is
presented and some of the current ideas for addressing them in the framework of
the seesaw mechanism of neutrino masses are discussed. Among the topics
discussed are ways to understand maximal mixing pattern among the three
neutrino species, both uni-maximal and bimaximal kinds. Constraints from
baryogenesis on mixing patterns are noted. In the last section, the question of
understanding the small masses for sterile neutrinos, which seem to be needed
for various reasons is addressed.


title:
Precise nondivergent analytic formulas for the radiative corrections to
  the beta energy spectrum in hyperon semileptonic decays over the entire
  Dalitz plot

abstract:
  Very accurate analytical expressions for the radiative corrections of
unpolarized hyperons semileptonic decays of charged and neutral baryons have
been obtained in the recent past. Some of these formulas contain logarithmic
singularities at the edges of the Dalitz plot for the three- and four-body
decays. These singularities are analyzed and integrated analytically to obtain
new divergentless formulas for the energy spectrum of the produced beta
particle. The new equations contain terms of the order alpha times the momentum
transfer, are applicable to any beta decay process and are suitable for a
model-independent experimental analysis.


title: Lattice QCD and the CKM matrix

abstract:
  These lectures (given at TASI 2000) provide an introduction to lattice
methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1 (Ch.
2) is a very vanilla introduction to lattice QCD. Lecture 2 (Ch. 3) describes
examples of recent lattice calculations relevant to fixing the parameters of
the CKM matrix.


title: B-Physics Phenomenology with Emphasis on the Light-Cone

abstract:
  Theoretical overviews on the B-physics are presented with an emphasis on the
light-cone degrees of freedom. Our new treatment of the embedded states seems
to give an encouraging result.


title: Quarkonium production and NRQCD matrix elements

abstract:
  Most recent calculations of quarkonium production are based on the NRQCD
factorization formalism. This formalism is reviewed. To make predictions about
specific cross section, universal NRQCD matrix elements need to be extracted
from experiments. Extractions from different experimental situations are
compared, with some emphasis on the extraction from LEP.


title:
Corrections to the Higgs Boson Masses and Mixings from Chargino, W and
  Charged Higgs Exchange Loops and Large CP Phases

abstract:
  One loop contributions to the Higgs boson masses and mixings from the
chargino sector consisting of the chargino, the W, and the charged Higgs boson
($\chi^+-W-H^+$) exchanges and including the effects of large CP violating
phases are computed. It is found that the chargino sector makes a large
contribution to the mixings of the CP even and the CP odd Higgs sectors through
the induced one loop effects and may even dominate the mixing generated by the
stop and the sbottom sectors. Effects of the chargino sector contribution to
the Higgs boson masses are also computed. It is found that the sum of the
$\chi^+-W-H^+$ exchange contribution lowers the lightest Higgs boson mass and
worsens the fine tuning problem implied by the LEP data. Phenomenological
implications of these results are discussed.


title: Reanalysis of CP Violation in K_L -> pi^+ pi^- gamma

abstract:
  We present a reanalysis of direct CP violation in the decay K_L -> pi^+ pi^-
gamma. We point out an existing discrepancy between the theoretical and
experimental definitions of epsilon'_{+-gamma}. Adopting the experimental
definition of epsilon'_{+-gamma}, we estimate that epsilon'_{+-gamma}/epsilon
could be as large as a few times 10^{-4} both within the standard model and
beyond. We discuss these estimates in detail and we also show how a judicious
choice of E_gamma cuts can increase the sensitivity of the observable
epsilon'_{+-\gamma} to the underlying CP violation.


title: The 3D Yang-Mills system. Lecture notes on the Karabali-Nair theory

abstract:
  The Schroedinger functional treatment of 2+1 D Yang-Mills theory is
recapitulated, in great calculational detail, by following three papers of
Karabali, Kim and Nair in 1998/99. The notes include the Hermitean WZW model,
regularization, the functional Hamiltonian, the string tension and the magnetic
mass problem of 4D hot gluons.


title: A new look at the pair-production width in a strong magnetic field

abstract:
  We reexamine the process $\gamma\to e^++ e^-$ in a background magnetic field
comparable to $B_c\equiv m_e^2/e$. This process is known to be non-perturbative
in the magnetic-field strength. However, it can be shown that the {\it moments}
of the above pair production width is proportional to the derivatives of photon
polarization function at the zero energy, which is perturbative in $B$. Hence,
the pair-production width can be easily obtained from the latter by the inverse
Mellin transform. The implications of our approach are discussed.


title:
Jet Quenching versus Jet Enhancement: A Quantitative Study of the
  BDMPS-Z Gluon Radiation Spectrum

abstract:
  We study the gluon radiation spectrum off a hard in-medium produced quark in
the multiple soft rescattering formalism of
Baier-Dokshitzer-Mueller-Peigne-Schiff, and of Zakharov (BDMPS-Z). Its
dependence on the quark and gluon energy, on the gluon transverse momentum, on
the in-medium pathlength and on the rescattering properties of the nuclear
medium is analyzed quantitatively. The two components of gluon radiation, the
hard vacuum radiation associated to the quark production vertex, and the
medium-induced rescattering contribution interfer destructively. For small
spatial extensions of the medium, this destructive interference overcompensates
the hard vacuum radiation, and the total medium-induced radiative energy loss
decreases proportional to L^3. Medium-induced gluon production dominates only
above a finite critical length which varies between 3 and more than 6 fm
depending on the rescattering properties of the medium. Deviations from the
BDMPS-L^2-behaviour persist above the critical length. The medium dependence of
the angular gluon distribution is dominated by Brownian transverse momentum
broadening. This results in a depletion of the low transverse momentum part of
both the hard and the medium-induced contribution. As a consequence, the
medium-induced energy loss outside a finite angular cone size can be more than
a factor two larger than the total medium-induced radiative energy loss. We
discuss implications of these results for the jet quenching signal in
relativistic heavy ion collisions at RHIC and LHC.


title:
Heavy-light mesons spectrum from the nonperturbative QCD in the einbein
  field formalism

abstract:
  The spectrum of B and D mesons (including the low lying orbitally and
radially excited states) is calculated using the quark-antiquark Hamiltonian
derived from QCD in the einbein field formalism. Spin-spin and spin-orbit terms
due to the confinement and OGE interactions are taken into account as
perturbations. Results for the masses and splittings are confronted to the
experimental and recent lattice data and are demonstrated to be in a reasonable
agreement with both. We find that the orbital excitations with l=2 and l=3 for
D meson lie approximately in the same region as its first radial excitation
that might solve the mystery of the extremely narrow D(2637) state recently
claimed by DELPHI Collaboration.


title: The Electroweak Interactions as a Confinement Phenomenon

abstract:
  We consider a model for the electroweak interactions based on the assumption
that physical particles are singlets under the gauge group SU(2). The concept
of complementarity explains why the standard model works with such an
extraordinary precision although the fermions and bosons of the model can be
viewed as composite objects of some more fundamental fermions and bosons. We
study the incorporation of QED in the model. Furthermore we consider possible
deviations from the standard model at very high energies, e.g. excited states
of the weak bosons.


title: Wilson Lines Near the Light Cone

abstract:
  We study the dynamics of Wilson lines near the light cone in QCD. Lattice
simulations of the near light cone Hamiltonian in SU(2) show that the
correlation mass at strong coupling vanishes at intermediate coupling, which
signals a continuum transition on the light cone. We point out the possible
relevance of this mass for high energy scattering.


title:
Comment on ``Neutrino oscillations in the early universe: how can large
  lepton asymmetry be generated?"

abstract:
  We comment on the recent paper by A. D. Dolgov, S. H. Hansen, S. Pastor and
D. V. Semikoz (DHPS) [Astropart. Phys. {\bf 14}, 79 (2000)] on the generation
of neutrino asymmetries from active-sterile neutrino oscillations. We
demonstrate that the approximate asymmetry evolution equation obtained therein
is an expansion, up to a minor discrepancy, of the well-established static
approximation equation, valid only when the supposedly new higher order
correction term is small. In the regime where this so-called ``back-reaction''
term is large and artificially terminates the asymmetry growth, their evolution
equation ceases to be a faithful approximation to the Quantum Kinetic Equations
(QKEs) simply because pure Mikheyev-Smirnov-Wolfenstein (MSW) transitions have
been neglected. At low temperatures the MSW effect is the dominant asymmetry
amplifier. Neither the static nor the DHPS approach contains this important
physics. Therefore we conclude that the DHPS results have sufficient veracity
at the onset of explosive asymmetry generation, but are invalid in the ensuing
low temperature epoch where MSW conversions are able to enhance the asymmetry
to values of order $0.2 - 0.37$. DHPS do claim to find a significant final
asymmetry for very large $\delta m^2$ values. However, for this regime the
effective potential they employed is not valid.


title: Exploring the structure of a possible light scalar nonet

abstract:
  We first review the work of the Syracuse group, which uses an effective
chiral Lagrangian approach, on meson-meson scattering. An illustration
providing evidence for the existence of a strange scalar resonance of mass
around 900 MeV is given. An attempt to fit this $\kappa (900)$ together with a
similarly obtained $\sigma (560)$ and the well known $a_0(980)$ and $f_0(980)$
into a nonet pattern suggests that the underlying structure is closer to a dual
quark-dual antiquark than to a quark-antiquark. A possible mechanism to explain
a next higher-in mass scalar meson nonet is also discussed. This involves
mixing between $q{\bar q}$ and $qq{\bar q} {\bar q}$ states.


title: A dynamic mass definition near the t t-bar threshold

abstract:
  Starting from general considerations about the different concepts which exist
for the definition of the quark mass near the pair production threshold, we
introduce the definition of a mass with a dynamic degree of freedom that
extends the previously given concept of the static PS mass.


title: The Neutron EDM in the SM : A Review

abstract:
  We review the status of the electric dipole moment (EDM) of neutron in the
Standard Model (SM). The contributions of the strong and electroweak
interactions are discussed seperately. In each case the structure of the
Lagrangian and the sources of CP violation are specified, and calculational
details are given subsequently. These two contributions to the neutron EDM
exist in any extension of the SM including supersymmetry, two--doublet models
as well as models with more than three generations of fermions. We do not
discuss the EDM in such extensions; however, we briefly summarize their
predictions with a detailed account of the related literature.


title: Photon and Pion Production at High $p_T$

abstract:
  We present a study of high-$p_T$ photon and pion production in hadronic
interactions, focusing on a comparison of the yields with expectations from
next-to-leading order perturbative QCD (NLO pQCD). We examine the impact of
phenomenological models of $k_T$ smearing (which approximate effects of
additional soft-gluon emission) on absolute predictions for photon and pion
production and their ratio.


title:
Vector Meson Dominance, Axial Anomaly and the Thermal behavior of
  $g_{\rho \omega \pi}(T)$

abstract:
  By using a thermal Finite Energy QCD Sum Rule, we are able to establish the
temperature dependence of the $g_{\omega \rho \pi}(T)$ strong coupling. It
turns out that this coupling decreases as a function of temperature, vanishing
at the critical temperature. This corresponds to a possible deconfining
phenomenological signal. This result, together with the Vector Meson Dominance
(VMD) expression for the amplitude $\pi ^{0} \to \gamma \gamma $, allows us to
establish that this amplitude also vanishes at the critical temperature, in
agreement with previous independent analysis. This results supports, once
again, the validity of VMD at finite temperature. Several posssible scenarios
are discussed. However, if VMD would not hold at finite temperature, then we
will not be able to find a prediction for the thermal behavior of the $\pi ^{0}
\to \gamma \gamma $ amplitude.


title: Some Recent Results from the Complete Theory of SUSY without R-parity

abstract:
  We review an efficient formulation of the complete theory of supersymmetry
without R-parity, where all the admissible R-parity violating terms
incorporated. Some interesting recent results will be discussed, including
newly identified 1-loop contributions to neutrino masses and electric dipole
moments of neutron and electron, resulted from R-parity violating LR squark and
slepton mixings.


title: The Higgs Boson Might Not Couple To B Quarks

abstract:
  We discuss an alternative version of the electroweak standard model, in which
only the heavy t quark, not the light fermions, couples to the Higgs boson with
a strength given by the standard model. The Higgs particle decays dominantly
into two gluons jets. The branching ratio for the 2 gamma decay is about 3.5%.
The Higgs particle would be a narrow object (width about 60 KeV), and its mass
might be consistent with the value given by typical estimates of radiative
effects measured by the LEP experiments.


title: On Possibility of Higgs Mechanism Break Down Due to the Instantons

abstract:
  Two-dimensional Abelian Higgs model is considered. It is shown that Higgs
mechanism of the gauge bosons masses generating is broken in presence of
instantons. It is supposed that discussion can be generalized into the standard
model of electroweak interactions.


title: Strange mesons from quark and hadron matter: a comparison

abstract:
  In a simplified model we study the hadronization of quark matter in an
expanding fireball, in particular the approach to a final hadronic composition
in equilibrium. Ideal hadron gas equilibrium constrained by conservation laws,
the fugacity parametrization, as well as linear and non-linear coalescence
approaches are recognized as different approximations to this in-medium quark
fusion process. It is shown that color confinement requires a dependence of the
hadronization cross section on quark density in the presence of flow (dynamical
confinement).


title:
Symmetry-breaking corrections to heavy-to-light B meson form factors at
  large recoil

abstract:
  Recently it has been shown that symmetries emerging in the heavy quark and
large recoil energy limit impose various relations on form factors that
parametrise the decay of B mesons into light mesons. These symmetries are
broken by perturbative effects. In this paper we discuss the structure of
heavy-to-light form factors including such effects and compute
symmetry-breaking corrections to first order in the strong coupling. As an
application of our results we consider the forward-backward asymmetry zero in
the rare decay B -> V l^+ l^- and the possibility to constrain potential new
physics contributions to the Wilson coefficient C_9.


title:
Four neutrino oscillation analysis of atmospheric neutrino data and
  application to long baseline experiments

abstract:
  Analyis of the Superkamiokande atmospheric neutrino data is presented in the
framework of four neutrinos without imposing constraints of Big Bang
Nucleosynthesis. Implications to long baseline experiments are briefly
discussed.


title: Synchrotron Production of Photons by a Two-body System

abstract:
  The power spectrum of the synchrotron radiation generated by the motion of a
two-body charged system in an accelerator is derived in the framework of the
Schwinger source theory. The final formula can be used to verify the Lorentz
length contraction of the two-body system moving in the synchrotron.


title: Active-Sterile neutrino oscillations and BBN+CMBR constraints

abstract:
  We show how active-sterile neutrino oscillations in the early Universe can
play an interesting role in explaining the current observations of CMBR
anisotropies and light element abundances. We describe different possible
phenomenological scenarios in the interpretation of present data and how
active-sterile neutrino oscillations can provide a viable theoretical
framework.


title: Phenomenology of the Electron Structure Function

abstract:
  Advantages of introducing the electron structure function (ESF) in electron
induced processes are demonstrated. Contrary to the photon structure function
it is directly measured in such processes. At present energies a simultaneous
analysis of both the electron and the photon structure functions gives an
important test of the experimentally applied methods. Estimates of the ESF at
currently measured momenta are given. At very high momenta contributions from
$W$ and $Z$ bosons together with $\gamma$-$Z$ interference can be observed.
Predictions for next generation of experiments are given.


title: The dipole picture of small x physics (a summary of the Amirim meeting)

abstract:
  A personal summary of the discussions which took place at the informal
meeting in Amirim, Israel from June 1-4 2000, concerning the dipole picture of
small-$x$ physics is presented. The broad aim of the meeting was to address the
question ``Has HERA reached a new QCD regime (at small $x$) ?''. The new regime
in question is the high-density, but weak-coupling, limit of perturbative QCD.


title: Weak form factors for heavy meson decays

abstract:
  We calculate the form factors for weak decays of $B_{(s)}$ and $D_{(s)}$
mesons to light pseudoscalar and vector mesons within a relativistic dispersion
approach based on the constituent quark picture.
  This approach gives the form factors as relativistic double spectral
representations in terms of the wave functions of the initial and final mesons.
The form factors have the correct analytic properties and satisfy general
requirements of nonperturbative QCD in the heavy quark limit. The effective
quark masses and meson wave functions are determined by fitting the quark model
parameters to lattice QCD results for the $B\to \rho$ transition form factors
at large momentum transfers and to the measured $D\to (K,K^*)l\nu$ decay rates.
This allows us to predict numerous form factors for all kinematically
accessible $q^2$ values.