title: Skewed and double distributions in pion and nucleon

abstract:
  We study the non-forward matrix elements of twist-2 QCD light-ray operators
and their representations in terms of skewed and double distributions,
considering the pion as well as the nucleon. We point out the importance of
explicitly including all twist-2 structures in the double distribution
representation, which naturally leads to a ``two-component'' structure of the
skewed distribution, with different contributions in the regions |X| > xi/2 and
|X| < \xi/2. We compute the skewed and double quark distributions in the pion
at a low normalization point in the effective chiral theory based on the
instanton vacuum. Also, we derive the crossing relations expressing the skewed
quark distribution in the pion through the distribution amplitude for two--pion
production. Measurement of the latter in two-pion production in gamma^* gamma
and gamma^* N reactions could provide direct information about the skewed as
well as the usual quark/antiquark-distribution in the pion.


title: Precision Calculation Project Report

abstract:
  The complete list of definitions for quantities relevant in the analysis of
SLD/LEP-1 results around the Z-resonance is given. The common set of
conventions adopted by the programs TOPAZ0 and ZFITTER, following the
recommendations of the LEP electroweak working group, is reviewed. The
relevance of precision calculations is discussed in detail both for
pseudo-observables (PO) and for realistic observables (RO). The
model-independent approach is also discussed. A critical assessment is given of
the comparison between TOPAZ0 and ZFITTER.


title:
Grand unified theory constrained supersymmetry and neutrinoless double
  beta decay

abstract:
  We analyze the contributions to the neutrinoless double $\beta$ decay
($0\nu\beta\beta$-decay) coming from the Grand Unified Theory (GUT) constrained
Minimal Supersymmetric Standard Model (MSSM) with trilinear R-parity breaking.
We discuss the importance of two-nucleon and pion-exchange realizations of the
quark-level $0\nu\beta\beta$-decay transitions. In this context, the questions
of reliability of the calculated relevant nuclear matrix elements within the
Renormalized Quasiparticle Random Phase Approximation (pn-RQRPA) for several
medium and heavy open-shell nuclei are addressed. The importance of gluino and
neutralino contributions to $0\nu\beta\beta$-decay is also analyzed. We review
the present experiments and deduce limits on the trilinear R-parity breaking
parameter $\lambda_{111}'$ from the non-observability of $0\nu\beta\beta$-decay
for different GUT constrained SUSY scenarios. In addition, a detailed study of
limits on the MSSM parameter space coming from the $B \to X_s \gamma$ processes
by using the recent CLEO and OPAL results is performed. Some studies in respect
to the future $0\nu\beta\beta$-decay project GENIUS are also presented.


title: The properties of the critical point in electroweak theory

abstract:
  We study the properties of the electroweak theory in the vicinity of the
critical point --- the endpoint of the first order phase transition line that
exists in a wide class of theories, including the Standard Model and a part of
the parameter space of the Minimal Supersymmetric Standard Model. We find that
the critical point belongs to the 3d Ising universality class. The endpoint in
the Standard Model is located at the Higgs mass below the existing experimental
lower bound, implying that there is no electroweak phase transition in this
theory.


title: Pion Fluctuations near the QCD Critical Point

abstract:
  A critical point of second order, belonging to the universality class of the
3d Ising model, has recently been advocated as a strong candidate for the
critical behaviour (at high temperatures) of QCD with non-zero quark masses.
The implications of this conjecture are investigated in the multiparticle
environment of high-energy collisions. A universal intermittency pattern of
pion-density fluctuations is found, at the critical point, and its association
to the critical exponents is discussed. A Monte Carlo simulation of critical
events, in heavy-ion collisions, reveals the detailed structure of these
fluctuations, suggesting a framework of (event-by-event) measurements in which
the critical theory of QCD may become falsifiable.


title:
Stronger constraints for nanometer scale Yukawa-type hypothetical
  interactions from the new measurement of the Casimir force

abstract:
  We consider the Casimir force including all important corrections to it for
the configuration used in a recent experiment employing an atomic force
microscope. We calculate the long-range hypothetical forces due to the exchange
of light and massless elementary particles between the atoms constituting the
bodies used in the experiment --- a dielectric plate and a sphere both covered
by two thin metallic layers. The corrections to these forces caused by the
small surface distortions were found to be essential for nanometer Compton wave
lengthes of hypothetical particles. New constraints for the constants of
Yukawa-type interactions are obtained from the fact that such interactions were
not observed within the limits of experimental accuracy. They are stronger up
to 140 times in some range than the best constraints known up date. Different
possibilities are also discussed to strengthen the obtained constraints in
several times without principal changes of the experimental setup.


title: CP Violation in Omega^- Decays

abstract:
  We estimate the CP-violating rate asymmetry for the decay Omega^- -> Cascade
+ pion. Within the standard model, we find that it could be as large as 2 x
10^(-5). This is significantly larger than the corresponding rate asymmetries
for other non-leptonic hyperon decays, which are typically less than 10^(-6).


title: Direct Instantons and Nucleon Magnetic Moments

abstract:
  We calculate the leading direct-instanton contributions to the operator
product expansion of the nucleon correlator in a magnetic background field and
set up improved QCD sum rules for the nucleon magnetic moments. Remarkably, the
instanton contributions are found to affect only those sum rules which had
previously been considered unstable. The new sum rules show good stability and
reproduce the experimental values of the nucleon magnetic moments with values
of $\chi$, the quark condensate magnetic susceptibility, consistent with other
estimates.


title: Electromagnetic Form Factors of Meson Transitions

abstract:
  Within the Dyson-Schwinger equation approach to modeling QCD for meson
physics, we present new results for $g_{\rho\pi\pi}$ and the coupling constants
and form factors for the transitions $\gamma^\ast \pi \rho$ and $\gamma^\ast
\pi^0 \gamma$. We discuss the role of the sub-dominant covariants of the $\pi$
Bethe-Salpeter amplitude and investigate the asymptotic behavior of the
$\gamma^\ast \pi^0 \gamma$ form factor.


title: Model Independent Analysis of the Solar Neutrino Data

abstract:
  We perform an updated model-independent analysis using all the latest solar
neutrino data, including the one coming from remarkably high statistics
SuperKamiokande experiment. We confirm that the astrophysical solutions to the
solar neutrino problem are extremely disfavored. We also present a new way of
illuminating the suppression pattern of various solar neutrino flux, which
indicates that the strong suppression of $^{7}$Be neutrinos is no more true
once the neutrino flavor conversion is taken into account.


title:
Pion-Pion Scattering in Chiral Perturbation and Dispersion Relation
  Theories

abstract:
  Chiral perturbation theory, the low energy effective theory of the strong
interactions for the light pseudoscalar degrees of freedom, is based on
effective Lagrangian techniques and is an expansion in the powers of the
external momenta and the powers of the quark masses, which correct the
soft-pion theorems. Our primary emphasis will be on the problem of $\pi\pi$
scattering. After briefly reviewing these features and some results, we review
some features of $\pi-N$ scattering.


title: Finally neutrino has mass

abstract:
  The present status of the problem of neutrino mass, mixing and neutrino
oscillations is briefly summarized. The evidence for oscillations of
atmospheric neutrinos found recently in the Super-Kamiokande experiment is
discussed. Indications in favor of neutrino oscillations obtained in solar
neutrino experiments and in the accelerator LSND experiment are also
considered. Implications of existing neutrino oscillation data for neutrino
masses and mixing are discussed.


title: A Parametrization for $K^+\to \pi^+\pi^- e^+\nu$

abstract:
  We discuss various models and Chiral Perturbation Theory results for the
$K_{l4}$ form factors $F$ and $G$. We check in how much a simple
parametrization with a few parameters can be used to extract information from
experiment.


title: The Sphaleron Rate: Where We Stand

abstract:
  I review what we know about the ``sphaleron rate'', which is the efficiency
of baryon number violation at high temperatures of order 100 GeV in the
Standard Model. The leading behavior at weak coupling in the symmetric phase is
known accurately; Gamma = (10.7 +- .7) (g^2 T^2 / m_D^2)
log(m_D/g^2T)\alpha_w^5 T^4. At realistic values of the coupling our accuracy
is worse. We also now have the tools to determine the rate nonperturbatively in
the broken electroweak phase; the sphaleron rate there is slower than
perturbative estimates.


title: Mass Splitting of Three Seesaw Neutrinos

abstract:
  If a family symmetry exists so that all three neutrinos have equal Majorana
masses (via the seesaw mechanism), then the breaking of this symmetry from
charged-lepton masses (via two-loop double $W$ exchange) implies $\Delta m$
less than about $10^{-9}m_0$. With the common mass $m_0 \sim$ eV for hot dark
matter, $\Delta m^2 \sim 10^{-10}$ eV$^2$ is natural for vacuum solar neutrino
oscillations.


title:
g_{K LAMBDA N} and g_{K SIGMA N} coupling constants in light cone QCD
  sum rules

abstract:
  The strong coupling constants g_{K LAMBDA N} and g_{K SIGMA N} for the
structure (sigma_{mu,nu} gamma_5) are calculated within light cone QCD sum
rules. A comparison of our results on these couplings with predictions from
traditional QCD sum rules is presented.


title: Effects of SM Kaluza-Klein excitations on electroweak observables

abstract:
  The presence of an extra dimension of size R \approx TeV^{-1} introduces a
tower of Kaluza-Klein gauge boson excitations that affects the standard model
(SM) relations between electroweak observables. The mixing of the W and Z
bosons with their excitations changes their masses and couplings to fermions.
This effect depends on the Higgs field, which may live in the bulk of the extra
dimension, on its boundary, or may be a combination of both types of fields. We
use high-precision electroweak data to constrain 1/R. We find limits from 1 to
3 TeV from different observables, with a model independent bound of 2.5 TeV.


title:
Distinguishing the Higgs scalars of NMSSM and Z' models for large Higgs
  trilinear couplings

abstract:
  Two well-known extended supersymmetric models, Z' models and NMSSM, are
comparatively analyzed in the limit of large trilinear Higgs couplings. The two
models are found to have distinguishable Higgs spectra at both tree- and loop-
levels. Higgs production through Bjorken processes at an $e^+e^-$ collider is
shown to discriminate between the two models.


title: Anomalous U(1) Gauge Symmetry and Lepton Flavor Violation

abstract:
  In recent years, many people have studied the possibility that the anomalous
U(1) gauge symmetry is a trigger of SUSY breaking and/or an origin of the
fermion mass hierarchy. Though it is interesting that the anomalous U(1)
symmetry may explain these two phenomena simultaneously, it causes a negative
stop mass squared or a severe fine-tuning in order to avoid the FCNC problem.
Recently, it was pointed out that the F-term contribution of the dilaton field
can dominate the flavor-dependent contribution from the anomalous U(1) D-term,
so that the FCNC problem may be naturally avoided. In this paper, we study the
case in which the dilaton is stabilized by the deformation of the K\"ahler
potential for the dilaton and find that the order of the ratio of the F-term to
the D-term contributions is generally determined. This implies that the
branching ratio of \mu \to e \gamma can be found around the present
experimental bound.


title: SUSY and Symmetry Nonrestoration at High Temperature

abstract:
  The status of internal symmetry breaking at high temperature in
supersymmetric models is reviewed. This phenomenon could solve some well known
cosmological problems, such as the domain wall, monopole and false vacuum
problems.


title:
Higher order corrections to parton showering from resummation
  calculations

abstract:
  The connection between analytic and Monte Carlo calculations of soft gluon
emission is reanalyzed in light of recent, theoretical developments in
resummation. An alternative Monte Carlo algorithm is suggested which
incorporates (1) corrections beyond leading order to the showering and (2)
smoothly merges with the higher order calculation of single, hard parton
emission. In particular, it is possible to study jet properties in heavy boson
production for all values of the boson transverse momentum with a total cross
section of NLO accuracy. The specific cases of $W$, $Z$ and Higgs boson
production at the Tevatron are addressed using a modified version of the Pythia
Monte Carlo.


title: Self-Dual Point and Unification

abstract:
  We hypothesize that the vacuum is spontaneously shifted from the self-dual
point in the moduli space, at which all dimensions are compact, and that the
true vacuum results from the decompactification of the four space-time
dimensions and remains in the vicinity of the self-dual point for extra
dimensions. On the basis of our hypotheses we explore new types of the coupling
unification which are not realized in the four-dimensional effective theory but
in the framework of the higher dimensional theory. In the $SU(6) \times
SU(2)_R$ string model, if the SU(6) gauge group lives in the world-volume of
9-branes and the $SU(2)_R$ in the world-volume of 5-branes, or {\it vice
versa}, unification solutions can be found in the vicinity of the self-dual
point.


title:
Vanishing Contribution to Quark Electric Dipole Moment in the 2HD Model
  with CKM CP Violation

abstract:
  In the standard model (SM) of electroweak interactions, CP noninvariance
arises from the nonzero phase in the CKM matrix. Its contribution to the quark
electric dipole moment (EDM) vanishes surprisingly at two loop order. This
makes the quark EDM extremely small in the SM. In this paper, we consider the
two Higgs doublet extension of the SM and assume that CP noninvariance is still
encoded in the CKM matrix. We calculate the charged Higgs boson contribution to
the quark EDM which naively should be of order
$eG_F^2\tilde{\delta}(4\pi)^{-4}m_{u(d)}m_t^2m_b^2m_H^{-2}$ for the up (down)
quark with possible enhancement factors of $\tan^2\beta$. Here $\tilde{\delta}$
is the rephasing invariant of CP violation. However, contrary to the above
naive expectation, we find that the charged Higgs boson contribution vanishes
strictly at two loop order. We show explicitly how this comes about and
explains how it is related to the general form of Yukawa couplings in a
spontaneously broken gauge theory.


title:
Bottom-Strange Associated Production at High Energy $e^{+}e^{-}$
  Colliders in Standard Model

abstract:
  We investigate the flavor changing neutral current bsV(V=$\gamma$,Z)
couplings in the production vertex for the process $e^+e^-\to b\bar s or \bar b
s$ in the standard model. The precise calculations keeping all quark masses
non-zero are carried out. Production cross sections are found to be the order
of $10^{-3}$ fb at LEP II and the order of $10^{-1}$ fb when center-of-mass
energy is near the mass of neutral gauge boson Z.


title:
S, T, U parameters in $SU(3)_C\times SU(3)_L\times U(1)$ model with
  right-handed neutrinos

abstract:
  The S, T, U parameters in the $ SU(3)_C\times SU(3)_L\times U(1)$ model with
right -handed neutrinos are calculated. Explicit expressions for the oblique
and Z - Z' mixing contributions are obtained. We show that the bilepton oblique
contributions to S and T parameters are bounded : $- 0.085 \stackrel{<}{\sim} S
\stackrel{<}{\sim} 0.05$ and $- 0.001 \stackrel{<}{\sim} T \stackrel{<}{\sim}
0.08$. The Z - Z' mixing contribution is positive and above 10%, but it will
increase fastly with the higher Z' mass. %can be negative. The consequent mass
splitting of the bilepton is derived and to be 15%. The limit on the mass of
the neutral bilepton in this model is obtained.


title: CP Violation in the Next to Minimal Supersymmetric Standard Model

abstract:
  We consider spontaneous CP violation in the Next to Minimal Supersymmetric
Standard Model (NMSSM), without the usual $Z_3$ discrete symmetry. CP violation
can occur at tree level, raising a potential conflict with the experimental
bounds on the electric dipole moments of the electron and neutron. One escape
from this is to demand that the CP violating angles are small, but we find that
this entails an unacceptably light neutral Higgs.


title:
A Next-to-Minimal model of Hybrid Inflation in Effective Supergravity
  Theories

abstract:
  We propose a model of inflation based on a simple variant of the NMSSM,
called $\phi$NMSSM where the additional singlet $\phi$ plays the role of the
inflaton in hybrid (or inverted hybrid) type models. The $\phi$NMSSM solves the
$\mu$ problem of the MSSM via the vacuum expectation value of the gauge singlet
N, but also solves the strong CP problem through an approximate Peccei-Quinn
symmetry. The potential energy which drives inflation originates from the
F-term of the effective supergravity theory which result from a generic string
theory. In the class of models considered the inflaton is protected from
receiving mass during inflation by a Heisenberg symmetry, avoiding the $\eta$
problem.


title: CP-odd WWZ couplings induced by vector-like quarks

abstract:
  A minimal extension of the standard model includes extra quarks with charges
2/3 and/or -1/3, whose left-handed and right-handed components are both SU(2)
singlets. This model predicts new interactions of flavor-changing neutral
current at the tree level, which also violate CP invariance. We study CP-odd
anomalous couplings for the gauge bosons W, W, and Z induced by the new
interactions at the one-loop level. These couplings become nonnegligible only
if both an up-type and a down-type extra quarks are incorporated. Their form
factors are estimated to be maximally of order $10^{-5}$. Such magnitudes are
larger than those predicted in the standard model, though smaller than those in
certain other models.


title: Proton Structure in Transverse Space and the Effective Cross Section

abstract:
  The observation of double parton collisions by CDF has provided the first
direct information on the structure of the proton in transverse space. The
actual quantity which has been measured is the `effective cross section'
$\sigma_{eff}$, which is related to the transverse size of the region where
hard interactions are localized. The actual value which has been measured is
sizably smaller than naively expected and it is an indication of important
correlation effects in the many-body parton distribution of the proton. We
discuss the problem pointing out a possible source of correlations in the
proton structure, which could have a significant effect on the value of
$\sigma_{eff}$.


title:
Non-Singlet Corrections of O(\alpha_s^2 G_F M_t^2) to \Gamma(Z\to
  b\bar{b})

abstract:
  The partial decay rate of the $Z$ boson into bottom quarks constitutes an
important decay channel. This is mainly due to the virtual presence of the top
quark in the loop diagrams giving rise to correction factors which are
quadratic in the top quark mass. At one- and two-loop order it turned out that
the leading term in the heavy-top expansion leads to very good approximations
to the exact result. In this work the non-singlet diagrams at O(\alpha_s^2 G_F
M_t^2) are considered.


title: Diffractive Photon Production in Gamma-P and Gamma-Gamma Interactions

abstract:
  We study the diffractive production of photons in gamma-p and gamma-gamma
collisions. We specifically compute the rates for gamma*-p -> gamma-X and for
gamma*-gamma* -> gamma-gamma, where X denotes the proton dissociation. We focus
on the rates at large momentum transfers, -t >> Lambda^2, where we are most
confident in the use of QCD perturbation theory. However, our calculations do
allow us to study the -t -> 0 behaviour of the gamma*-gamma*-> gamma-gamma
process in the region where the incoming photons are sufficiently virtual.


title: A Critical Look at Rescattering Effects on $\gamma$ from $B^+\to K\pi$

abstract:
  Three ways are compared of dealing with rescattering effects in $B^{\pm}\to
K^0\pi^{\pm}$, in order to determine the weak phase $\gamma$ from these
processes and $B^{\pm}\to K^{\pm}\pi^0$. We find that neglecting these
contributions altogether may involve sizable errors in $\gamma$, depending on
the rescattering amplitude and on the value of a certain measurable strong
phase. We show that an attempt to eliminate these effects by using the
charge-averaged rate of $B^{\pm}\to K^{\pm}K^0$ suffers from a large
theoretical error due to SU(3) breaking, which may be resolved when using also
the processes $B^{\pm}\to \pi^{\pm}\eta_8$.


title:
Higgs production with large transverse momentum in hadronic collisions
  at next-to-leading order

abstract:
  Inclusive associated production of a light Higgs boson (m_H < m_t) with one
jet in pp collisions is studied in next-to-leading order QCD. Transverse
momentum (p_T < 30 GeV) and rapidity distributions of the Higgs boson are
calculated for the LHC in the large top-quark mass limit. It is pointed out
that, as much as in the case of inclusive Higgs production, the K-factor of
this process is large (~1.6) and depends weakly on the kinematics in a wide
range of transverse momentum and rapidity intervals. Our result confirms
previous suggestions that the production channel p+p -> H+jet ->
gamma+gamma+jet gives a measurable signal for Higgs production at the LHC in
the mass range 100-140 GeV, crucial also for the ultimate test of the Minimal
Supersymmetric Standard Model.


title: Resummation for heavy quark and jet cross sections

abstract:
  We review the resummation of threshold logarithms for heavy quark, dijet,
direct photon, and W boson production cross sections in hadronic collisions.
Beyond leading logarithms the resummed cross section is sensitive to the color
exchange in the hard scattering. The resummation is formulated at
next-to-leading logarithmic or higher accuracy in terms of anomalous dimension
matrices which describe the factorization of soft gluons from the hard
scattering. We give results for the soft anomalous dimension matrices at one
loop for the full range of partonic subprocesses involved in heavy quark,
dijet, direct photon, and W boson production. We discuss the general
diagonalization procedure that can be implemented for the calculation of the
resummed cross sections, and we give numerical results for top quark production
at the Fermilab Tevatron. We also present analytical results for the one- and
two-loop expansions of the resummed cross sections.


title:
Derivation of the Effective Chiral Lagrangian for Pseudoscalar Mesons
  from QCD

abstract:
  We formally derive the chiral Lagrangian for low lying pseudoscalar mesons
from the first principles of QCD considering the contributions from the normal
part of the theory without taking approximations. The derivation is based on
the standard generating functional of QCD in the path integral formalism. The
gluon-field integration is formally carried out by expressing the result in
terms of physical Green's functions of the gluon. To integrate over the
quark-field, we introduce a bilocal auxiliary field Phi(x,y) representing the
mesons. We then develop a consistent way of extracting the local pseudoscalar
degree of freedom U(x) in Phi(x,y) and integrating out the rest degrees of
freedom such that the complete pseudoscalar degree of freedom resides in U(x).
With certain techniques, we work out the explicit U(x)-dependence of the
effective action up to the p^4-terms in the momentum expansion, which leads to
the desired chiral Lagrangian in which all the coefficients contributed from
the normal part of the theory are expressed in terms of certain Green's
functions in QCD. Together with the existing QCD formulae for the anomaly
contributions, the present results leads to the complete QCD definition of the
coefficients in the chiral Lagrangian. The relation between the present QCD
definition of the p^2-order coefficient F_0^2 and the well-known approximate
result given by Pagels and Stokar is discussed.


title: Exclusive B --> K^* l^+ l^-$ decay in the three Higgs doublet model

abstract:
  We study the differential Branching ratio and CP asymmetry for the exclusive
decay B --> K^* l^+ l^- in the three Higgs doublet model with additional global
O(2) symmetry in the Higgs sector. We analyse dilepton mass square q^2
dependency of the these quantities. Further, we study the effect of new
parameter of the global symmetry in the Higgs sector on the differential
branching ratio and CP asymmetry. We see that there exist an enhancement in the
branching ratio and a considerable CP violation for the relevant process. In
addition to this, we realize that fixing dilepton mass gives information about
the sign of the Wilson coefficient C_7^{eff}.Therefore, the future measurements
of the CP asymmetry for B\to K^* l^+ l^- decay will give a powerful information
about the sign of Wilson coefficient C_{7}^{eff} and new physics beyond the SM.


title:
Aspects of Neutrino Masses and Lepton-Number Violation in the light of
  the Super-Kamiokande data

abstract:
  We discuss aspects of neutrino masses and lepton-number violation, in the
light of the observations of Super-Kamiokande. As a first step, we use the data
from various experiments, in order to obtain a phenomenological understanding
of neutrino mass textures. We then investigate how the required patterns of
neutrino masses and mixings are related to the flavour structure of the
underlying theory. In supersymmetric extensions of the Standard Model,
renormalisation group effects can have important implications: for small tanb,
bottom-tau unification indicates the presence of significant muon-tau flavour
mixing. The evolution of the neutrino mixing may be described by simple
semi-analytic expressions, which confirm that, for large tanb, very small
mixing at the GUT scale may be amplified to maximal mixing at low energies, and
vice versa. Passing to specific models, we first discuss the predictions for
neutrino masses in different GUT models (including superstring-embedded
solutions). Imposing the requirement for successful leptogenesis may give
additional constraints on the generic structure of the neutrino mass textures.
Finally, we discuss direct ways to look for lepton-number violation in
ultra-high energy neutrino interactions.


title: Final State Interactions in $D^0 \to K^0 \bar{K^0}$

abstract:
  It is believed that the production rate of $D^0\to K^0\bar K^0$ is almost
solely determined by final state interactions (FSI) and hence provides an ideal
place to test FSI models. Here we examine model calculations of the
contributions from s-channel resonance $f_J(1710)$ and t-channel exchange to
the FSI effects in $D^0\to K^0\bar K^0$. The contribution from s-channel
$f_0(1710)$ is sma$ For the t-channel FSI evaluation, we employ the
one-particle-exchange (OPE) model and Regge model respecti$ The results from
two methods are roughly consistent with each other and can reproduce the large
rate of $D^0\to K^0\bar K^0$ reasonably well$


title:
Isospin Invariance and Generalized Bose Statistics applied to Low Energy
  $K^{+-}K^0$ and $\pi^{+-}\pi^0$ Space Symmetries

abstract:
  The use of isospin invariance and Generalized Bose statistics shows that the
Bose-Einstein correlation (BEC) of identical bosons seen in the $K^+K^+$ and
$\pi^+ \pi^+$ systems can be extended to apply to $K^+ K^o$ and $\pi^+ \pi^o$
pairs when they are produced from an initial state with isospin zero; e.g. by
the fragmentation of gluons or of a strange quark pair accompanied by gluons.
This might be useful in constructing more realistic model dependent Monte Carlo
programs for the investigation of the isospin structure of the particles
produced in a given kinematic region like the central region in high energy
hadronic collisions or quark-gluon plasma. Some of the consequences of this
extension are here applied to the hadronic $Z^o$ decays. In particular the
study addresses the question how much of the observed low $K^o_S K^o_S$ mass
enhancement is to be attributed to a BEC effect and how much to the
$f_0(980)\to K^o_S K^o_S$ decay. Finally we point out the restrictions imposed
by the extension on the choice of reference samples for the BEC studies.


title: Semileptonic and rare B meson decays into a light pseudoscalar meson

abstract:
  In the framework of a QCD relativistic potential model we evaluate the form
factors describing the exclusive decays B => \pi l nu and B => K l+ l-. The
present calculation extends a previous analysis of B meson decays into light
vector mesons. We find results in agreement with the data, when available, and
with the theoretical constraints imposed by the Callan-Treiman relation and the
infinite heavy quark mass limit.


title:
Long-Lived Superheavy Particles in Dynamical Supersymmetry-Breaking
  Models in Supergravity

abstract:
  Superheavy particles of masses $\simeq 10^{13}-10^{14} GeV$ with lifetimes
$\simeq 10^{10}-10^{22} years$ are very interesting, since their decays may
account for the ultra-high energy (UHE) cosmic rays discovered beyond the
Greisen-Zatsepin-Kuzmin cut-off energy $E \sim 5 \times 10^{10} GeV$. We show
that the presence of such long-lived superheavy particles is a generic
prediction of QCD-like SU(N_c) gauge theories with N_f flavors of quarks and
antiquarks and the large number of colors N_c. We construct explicit models
based on supersymmetric SU(N_c) gauge theories and show that if the dynamical
scale $\Lambda \simeq 10^{13}-10^{14} GeV$ and N_c = 6-10 the lightest
composite baryons have the desired masses and lifetimes to explain the UHE
cosmic rays. Interesting is that in these models the gaugino condensation
necessarily occurs and hence these models may play a role of so-called hidden
sector for supersymmetry breaking in supergravity.


title: The $N-\Delta$ Weak Axial-Vector Amplitude $C_{5}^a(0)$

abstract:
  The weak $N-\Delta$ axial-vector transition amplitude $<\Delta| A_{\pi
^{+}}^\mu |N>$ - important in $N^{*}$ production processes in general and in
isobar models describing $\nu_\mu N\to \mu \Delta$ processes in particular - is
examined using a broken symmetry algebraic approach to QCD which involves the
realization of chiral current algebras. We calculate a value for the form
factor $C_{5}^{A}(0)$ in good agreement with experiment.


title: Fermion texture and sterile neutrinos

abstract:
  An explicit form of charged--lepton mass matrix, predicting $m_\tau =
1776.80$ MeV from the experimental values of $m_e$ and $m_\mu$ (in good
agreement with the experimental figure $m_\tau = 1777.05^{+0.29}_{-0.26}$ MeV),
is applied to three neutrinos $\nu_e, \nu_\mu, \nu_\tau$ in order to correlate
tentatively their masses and mixing parameters. It is suggested that for
neutrinos the diagonal elements of the mass matrix are small versus its
off-diagonal elements. Under such a conjecture, the neutrino masses, lepton
\CKM matrix and neutrino oscillation probabilities are calculated in the
corresponding lowest perturbative order. Then, the nearly maximal mixing of
$\nu_\mu$ and $\nu_\tau$ is predicted in consistency with the observed deficit
of atmospheric $\nu_\mu$'s. However, the predicted deficit of solar $\nu_e$'s
is much too small to explain the observed effect, what suggests the existence
of (at least) one sort, $\enu$, of sterile neutrinos, whose mixing with $\nu_e$
would be responsible for the observed deficit. Perspectives for applying the
same form of mass matrix to quarks are also outlined. Two independent
predictions of $|V_{ub}|/|V_{cb}| = 0.0753 \pm 0.0032$ and unitary angle
$\gamma \simeq 70^\circ$ are deduced from the experimental values of $|V_{us}|$
and $|V_{cb}|$ (with the use of quark masses m_s, m_c and m_b). In the last
three Sections, the option of two sorts, $\enu$ and $\mnu$, of sterile
neutrinos is considered. They may dominate neutrino mixing, and even cause that
two extra neutrino mass states (arising then) are agents of some tiny neutrino
instability and related damping of $\nu_e$ and $\nu_\mu$ oscillations. In
Appendix, three conventional Majorana sterile neutrinos are discussed.


title:
Comment on the paper: ``Neutrino pair production by a virtual photon in
  an external magnetic field'' by Zhukovskii et al

abstract:
  We point out some serious mistakes in the investigation of Zhukovskii et al.
Both the amplitude and the probability of the process were calculated wrongly,
that is, the problem of the neutrino pair production by a virtual photon in an
external magnetic field is still unsolved.


title: The SM as the Quantum Low Energy Effective Theory of the MSSM

abstract:
  In the framework of the Minimal Supersymmetric Standard Model we compute the
one-loop effective action for the electroweak bosons obtained after integrating
out the different sleptons, squarks, neutralinos and charginos, and present the
result in terms of the physical sparticle masses. In addition we study the
asymptotic behaviour of the two, three and four point Green's functions with
external electroweak bosons in the limit where the physical sparticle masses
are very large in comparison with the electroweak scale. We find that in this
limit all the effects produced by the supersymmetric particles can be, either
absorbed in the Standard Model parameters and gauge bosons wave functions, or
else they are supressed by inverse powers of the supersymmetric particle
masses. This work, therefore, completes the proof of decoupling of the heavy
supersymmetric particles from the standard ones in the electroweak bosons
effective action and in the sense of the Appelquist-Carazzone Theorem that we
started in a previous work. From the point of view of effective field theories
this work can be seen as a (partial) proof that the SM can be obtained indeed
from the MSSM as the quantum low energy effective theory of this latter when
the SUSY spectra is much heavier than the electroweak scale.


title:
Radiative corrections to top quark decay into charged Higgs at the
  Tevatron

abstract:
  We present the computation of the leading one-loop electroweak radiative
corrections to the non-standard top quark decay width Gamma(t->H+ b), using a
physically motivated definition of tan(beta). We find that the corrections are
large, both in the Minimal Supersymmetric Standard Model (MSSM) and the
Two-Higgs-Doublet Model (2HDM). These corrections have an important effect on
the interpretation of the Tevatron data, leading to the non-existence of a
model-independent bound in the tan(beta)-MH+ plane.


title:
Gamma(H+ -> t \bar{b}) in the MSSM: a handle for SUSY charged Higgs at
  the Tevatron and the LHC

abstract:
  We compute Gamma(H+ -> t \bar{b}) at one-loop in the MSSM and show how future
data at the Tevatron and/or at the LHC could be used to unravel the potential
SUSY nature of the charged Higgs.


title: Stop Squark Search at Tevatron in the Light Slepton Scenario

abstract:
  In minimal supergravity based supersymmetry models the charged sleptons as
well as the sneutrinos may be lighter than the squarks. In such light slepton
scenario the search for lighter stop squark has been investigated in the
dilepton + missing $p_T(\missingpt)$ +jets ($\ge 1$) channel at Tevatron. In
this scenario semileptonic decay of lighter stop squark has been considered via
off shell and on shell charginos. In the latter case the chargino undergoes
pure leptonic 2-body decay. We observe that for some favourable region of the
MSSM parameter space one can probe lighter stop squark mass upto 140 GeV with
few events in the present data set for which the luminosity is 110 pb$^{-1}$.
At the MI upgrade one is likely to end up with more events.


title:
Complete Calculations of Wb\bar b and Wb\bar b + jet Production at
  Tevatron and LHC: Probing Anomalous Wtb Couplings in Single Top Production

abstract:
  We present the results of a complete tree level calculation of the processes
pp(\bar p) -> Wb\bar b and Wb\bar b + jet that includes the single top signal
and all irreducible backgrounds simultaneously. In order to probe the structure
of the Wtb coupling with the highest possible accuracy and to look for possible
deviations from standard model predictions, we identify sensitive observables
and propose an optimal set of cuts which minimizes the background compared to
the signal. At the LHC, the single top and the single anti-top rates are
different and the corresponding asymmetry yields additional information. The
analysis shows that the sensitivity for anomalous couplings will be improved at
the LHC by a factor of 2--3 compared to the expectations for the first
measurements at the upgraded Tevatron. Still, the bounds on anomalous couplings
obtained at hadron colliders will remain 2--8 times larger than those from high
energy gamma-e colliders, which will, however, not be available for some time.
All basic calculations have been carried out using the computer package
CompHEP. The known NLO corrections to the single top rate have been taken into
account.


title:
Running mass of the rho0 meson's implication for the dilepton mass
  spectrum and the mu+mu-/e+e- branching ratio in the K+ --> pi+l+l- decays

abstract:
  We make an attempt to resolve the discrepancy of the observed e+e- mass
spectrum in the K+ --> pi+e+e- decay with that predicted by meson dominance. To
this end we investigate the properties of the rho0 propagator. We use
dispersion relations to evaluate the running mass squared m_rho^2(t) of the
rho0 resonance without adjustable parameters. To improve the convergence of the
dispersion integral, the momentum dependence of strong vertices is taken from
the flux-tube-breaking model of Kokoski and Isgur. The obtained behavior of
m_rho^2(t) at small momentum squared t makes the K+ --> pi+e+e- form factor
rise faster with increasing $t$ than in the original meson-dominance
calculation and more in agreement with the published data. As a consequence,
the meson-dominance prediction of the mu+mu-/e+e- branching ratio changes
slightly, from 0.224 to 0.236. We do not see any possibility to accommodate
into the meson-dominance approach an even steeper e+e- spectrum, indicated by
the preliminary data of the E865 collaboration at BNL AGS.


title: Radiative decay of rho^0 and phi mesons in a chiral unitary approach

abstract:
  We study the rho^0 and phi decays into pi^+ pi^- gamma, pi^0 pi^0 gamma and
phi into pi^0 eta gamma using a chiral unitary approach to deal with the final
state interaction of the M M system. The final state interaction modifies only
moderately the large momenta tail of the photon spectrum of the rho^0 --> pi^+
pi^- gamma decay. In the case of phi decay the contribution to pi^+ pi^- gamma
and pi^0 pi^0 gamma decay proceeds via kaonic loops and gives a distribution of
pi pi invariant masses in which the f_0(980) resonance shows up with a very
distinct peak. The spectrum found for phi --> pi^0 pi^0 gamma decay agrees with
the recent experimental results obtained at Novosibirsk. The branching ratio
for phi --> pi^0 eta gamma, dominated by the a_0(980), is also in agreement
with recent Novosibirsk results.


title:
Associated Production of Higgs Bosons with Scalar Quarks at Future
  Hadron and $e^+e^-$ Colliders

abstract:
  We analyze the production of neutral Higgs particles in association with the
supersymmetric scalar partners of the third generation quarks at future
high--energy hadron colliders [upgraded Tevatron, LHC] and $e^+e^-$ linear
machines [including the $\gamma \gamma$ option]. In the Minimal Supersymmetric
extension of the Standard Model, the cross section for the associated
production of the lightest neutral $h$ boson with the lightest top squark pairs
can be rather substantial at high energies. This process would open a window
for the measurement of the $h \tilde{t} \tilde{t}$ coupling, the potentially
largest coupling in the supersymmetric theory.


title: Particles in Loops - From Electrons to Top Quarks

abstract:
  This article, in memory of Professor Hiroshi Suura, is devoted to the effects
of particles in loops, ranging from quantum electrodynamics to precise tests of
the electroweak theory and CP violation.


title: Polarization and Spin Effects in Neutralino Production and Decay

abstract:
  We study the production of neutralinos e^+ e^- ->chi^0_i \chi^0_j with
polarized beams and the subsequent decays chi^0_i -> chi^0_k l^+ l^- and
chi^0_j -> chi^0_l l^+ l^-, including the complete spin correlations between
production and decay. We present analytical formulae for the differential cross
section of the combined process of production and decay of neutralinos. We also
allow for complex couplings. The spin correlations have a strong influence on
the decay angular distributions and the corresponding forward-backward
asymmetries. They are very sensitive to the SUSY parameters and depend strongly
on the beam polarizations. We present numerical results for the cross section
and the electron forward-backward asymmetry for e^+ e^- -> chi^0_1 chi^0_2,
chi^0_2 -> chi^0_1 e^+ e^-. We study the dependence on the parameter M' for
various mass splittings between tilde{e}_L and tilde{e}_R and different beam
polarizations.


title:
Colour Octet Contribution in Exclusive P-Wave Charmonium Decay into
  Proton-Antiproton

abstract:
  In inclusive P-wave charmonium decay, to cancel infrared divergence in the
colour singlet contribution requires the inclusion of the colour octet which
becomes degenerate with the former in the infrared limit. In the corresponding
exclusive decay, such an infrared divergence does not exist. On this ground, it
becomes doubtful whether the colour octet is needed in exclusive reactions. A
contradiction in the underlying picture, however, would result once all strong
decay channels are summed. We provide an answer to this question in support of
the colour octet with theoretical arguments as well as an explicit calculation
of Chi_J ---> p \bar p.


title: Curved QCD string dynamics

abstract:
  We consider the effects of going beyond the approximation of a straight
string in mesons by using a flexible flux tube model wherein a Nambu-Goto
string bends in response to quark accelerations. The curved string is
dynamically identical to the straight string even for ultra-relativistic mesons
except for a small additional radial momentum. We numerically solve the curved
string model in the case where both ends have equal mass quarks and also the
case where one end is fixed. No approximation of non-relativistic motion is
made. We note some small but interesting difference from the straight string.


title: On QCD and $\omega-\rho$ mixing

abstract:
  The evaluation of sum rules and vacuum condensates used in the calculation of
the mixing parameters of the $\omega -\rho$ system involve dangerous
cancellations of large numbers. In this note the contribution of the continuum
is eliminated in order to avoid such a large source of uncertainty. It is also
seen that the hypothesis of vacuum saturation used in the estimate of the
dimension 6 condensate is inadequate. The value obtained for the parameter
$\beta$ which governs the off-shell variation of the $\omega -\rho$ mixing is
$\beta=.25$.


title:
Rapid Asymmetric Inflation and Early Cosmology in Theories with
  Sub-Millimeter Dimensions

abstract:
  It was recently pointed out that the fundamental Planck mass could be close
to the TeV scale with the observed weakness of gravity at long distances being
due the existence of new sub-millimeter spatial dimensions. In this picture the
standard model fields are localized to a $(3+1)$-dimensional wall or
``3-brane''. We show that in such theories there exist attractive models of
inflation that occur while the size of the new dimensions are still small. We
show that it is easy to produce the required number of efoldings, and further
that the density perturbations $\delta\rho/\rho$ as measured by COBE can be
easily reproduced, both in overall magnitude and in their approximately
scale-invariant spectrum. In the minimal approach, the inflaton field is just
the moduli describing the size of the internal dimensions, the role of the
inflationary potential being played by the stabilizing potential of the
internal space. We show that under quite general conditions, the inflationary
era is followed by an epoch of contraction of our world on the brane, while the
internal dimensions slowly expand to their stabilization radius. We find a set
of exact solutions which describe this behavior, generalizing the well-known
Kasner solutions. During this phase, the production of bulk gravitons remains
suppressed. The period of contraction is terminated by the blue-shifting of
Hawking radiation left on our wall at the end of the inflationary de Sitter
phase. The temperature to which this is reheated is consistent with the
normalcy bounds. We give a precise definition of the radion moduli problem.


title: On the Spin content of the Nucleon

abstract:
  A QCD sum rule calculation of Balistky and Ji on the spin content of the
nucleon is done with a different approach to the evaluation of the bilocal
contributions and to the extraction of the nucleon pole residues. The result
obtained is much more numerically stable which puts their conclusion that about
half of the nucleon spin is carried by gluons on firmer ground.


title: The second order QCD contribution to the semileptonic b -> u decay rate

abstract:
  The order alpha_s^2 contribution to the inclusive semileptonic decay width of
a b quark \Gamma(b -> X_u e \bar{\nu}_e) is calculated analytically for zero
mass u quarks.


title: The Sphaleron in a Magnetic Field and Electroweak Baryogenesis

abstract:
  The presence of a primordial magnetic field in the early universe affects the
dynamic of the electroweak phase transition enhancing its strength. This effect
may enlarge the window for electroweak baryogenesis in the minimal
supersymmetric extension of the standard model or even resurrect the
electroweak baryogenesis scenario in the standard model. We compute the
sphaleron energy in the background of the magnetic field and show that, due to
the sphaleron dipole moment, the barrier between topologically inequivalent
vacua is lowered. Therefore, the preservation of the baryon asymmetry calls for
a much stronger phase transition than required in the absence of a magnetic
field. We show that this effect overwhelms the gain in the phase transition
strength, and conclude that magnetic fields do not help electroweak
baryogenesis.


title:
Diffraction driven steep rise of spin structure function
  $g_{LT}=g_{1}+g_{2}$ at small x and DIS sum rules

abstract:
  We derive a unitarity relationship between the spin structure function
$g_{LT}(x,Q^{2})=g_{1}(x,Q^{2})+g_{2}(x,Q^{2})$, the LT interference
diffractive structure function and the spin-flip coupling of the pomeron to
nucleons. Our diffractive mechanism gives rise to a dramatic small-$x$ rise
$g_{LT}(x,Q^{2}) \sim g^{2}(x,\bar{Q}^{2}) \sim (1/x)^{2(1+\delta_{g})}$, where
$\delta_{g}$ is an exponent of small-$x$ rise of the unpolarized gluon density
in the proton $g(x,\bar{Q}^{2})$ at a moderate hard scale $\bar{Q}^{2}$ for
light flavour contribution and large hard scale $\bar{Q}^{2} \sim m_{f}^{2}$
for heavy flavour contribution. It invalidates the Burkhardt-Cottingham sum
rule. The found small-$x$ rise of diffraction driven $g_{LT}(x,Q^{2})$ is
steeper than given by the Wandzura-Wilczek relation under conventional
assumptions on small-$x$ behaviour of $g_{1}(x,Q^{2})$.


title: Testing Higgs Self-couplings at e^+e^- Linear Colliders

abstract:
  To establish the Higgs mechanism sui generis experimentally, the self-energy
potential of the Higgs field must be reconstructed. This task requires the
measurement of the trilinear and quadrilinear self-couplings, as predicted, for
instance, in the Standard Model or in supersymmetric theories. The couplings
can be probed in multiple Higgs production at high-luminosity e^+e^- linear
colliders. Complementing earlier studies to develop a coherent picture of the
trilinear couplings, we have analyzed the production of pairs of neutral Higgs
bosons in all relevant channels of double Higgs-strahlung, associated multiple
Higgs production and WW/ZZ fusion to Higgs pairs.


title: A short look at epsilon'/epsilon

abstract:
  We analyze the theoretical implications of the new KTeV measurement of direct
CP-violation in K->pi pi decays. The result is found consistent with the
Standard Model for low values of the strange quark mass m_s. If the hadronic
parameters B_6^{(1/2)} and B_8^{(3/2)} satisfy 2 B_6^{(1/2)} - B_8^{(3/2)} < 2,
as suggested by lattice and 1/N_c calculations, we find an upper bound of 110
MeV for m_s (2 GeV)$. We parametrize potential new physics contributions to
\epsilon'/\epsilon and illustrate their correlation with upper bounds on m_s.
Finally we discuss a non-perturbative mechanism, which is not contained in the
existing calculations of B_6^{(1/2)}. This mechanism enhances B_6^{(1/2)} and
thereby leads to a better understanding of the Delta I=1/2 rule and the high
measured value of Re (\epsilon^\prime/\epsilon)


title: Distinguishing WH and WBBbar production at the Fermilab Tevatron

abstract:
  The production of a Higgs boson in association with a W-boson is the most
likely process for the discovery of a light Higgs at the Fermilab Tevatron.
Since it decays primarily to b-quark pairs, the principal background for this
associated Higgs production process is WBBbar, where the BBbar pair comes from
the splitting of an off mass shell gluon. In this paper we investigate whether
the spin angular correlations of the final state particles can be used to
separate the Higgs signal from the WBBbar background. We develop a general
numerical technique which allows one to find a spin basis optimized according
to a given criterion, and also give a new algorithm for reconstructing the W
longitudinal momentum which is suitable for the WH and WBBbar processes.


title: Remarks on Goldstone bosons and hard thermal loops

abstract:
  The hard thermal loop effective action for Goldstone bosons is deduced by
symmetry arguments from the corresponding result for gauge bosons. Pseudoscalar
mesons in Chromodynamics and magnons in an antiferromagnet are discussed as
special cases, including the hard thermal loop contribution to their
scattering.


title: Relations between the K_{l3} and tau --> K pi nu_tau decays

abstract:
  We investigate the relations between the K_{l3} and tau --> K pi nu_tau
decays using the meson dominance approach. First, the experimental branching
fractions (BF) for K^-_{e3} and K^0_{e3} are used to fix two normalization
constants (isospin invariance is not assumed). Then, the BF of tau^- -->
K^*(892)^- nu_tau is calculated in agreement with experiment. We further argue
that the nonzero value of the slope parameter lambda_0 of the K^-_{mu3} and
K^0_{mu3} form factors f_0(t) implies the existence of the tau^- -->
K_0^*(1430)^- nu_tau decay. We calculate its BF, together with BF's of the
K^-_{mu3}, K^0_{mu3}, tau- --> K^- pi^0 nu_tau, and tau- --> antiK^0 pi^0
nu_tau decays, as a function of the lambda_0 parameter. At some value of
lambda_0, different for charged and neutral kaons, calculated BF's seem to
match existing data and a prediction is obtained for the tau^- --> K pi nu
decays going through the K_0^*(1430)^- resonance.


title:
a_0(980) -> gamma gamma and f_0(980) -> gamma gamma: a consistent
  description

abstract:
  We work out the Linear Sigma Model (LSM) predictions for the 2 gamma decay
rates of the a_0(980),f_0(980) mesons under the assumption that they are
respectively the I=1 and I=0 members of the bar q q scalar nonet. Agreement
with experimental data is achieved provided we include the contribution of a
\kappa meson with mass approx. 900 MeV, and a scalar mixing angle (sigma -f_0
mixing in the {|NS>,|S>} basis) varphi_s approx. -14^\circ, as predicted by the
model.


title:
Imaging the Space-Time Evolution of High Energy Nucleus-Nucleus
  Collisions with Bremsstrahlung

abstract:
  The bremsstrahlung produced when heavy nuclei collide is estimated for
central collisions at the Relativistic Heavy Ion Collider. Bremsstrahlung
photons with energies below 100 to 200 MeV are sufficient to discern the gross
features of the space-time evolution of electric charge, if they can be
separated from other sources of photons experimentally. This is illustrated
explicitly by considering two very different models, one Bjorken-like, the
other Landau-like, both of which are constructed to give the same final charge
rapidity distribution.


title:
Colour Octet Contribution in Exclusive P-Wave Charmonium Decay into
  Octet and Decuplet Baryons

abstract:
  In the last years, the need of the colour octet state in inclusive P-wave
charmonium decay has been firmly established. However, the implications of this
in the corresponding exclusive reactions have not been fully recognized. We
argue for the necessity of the colour octet in P- and higher-wave quarkonium
decay. Using a set of phenomenologically constructed baryon wavefunctions, we
consider the Chi_J decay into octet and decuplet baryon-antibaryon pair. By
doing so, we subject the wavefunctions to a test of applicability. We show that
the colour singlet component alone is insufficient to account for experimental
measurements and only by including the colour octet contribution can the
partial theoretical decay widths be brought into range of the data. By the
present and earlier applications of the set of wavefunctions, they show
themselves to be reasonable model wavefunctions at around the scale Q^2 \sim
10-20 GeV^2.


title: SUSY Production Cross Sections

abstract:
  We summarize the status of next-to-leading order perturbative quantum
chromodynamics (pQCD) calculations of the cross sections for the production of
squarks, gluinos, neutralinos, charginos, and sleptons as a function of the
produced sparticle masses in proton-antiproton collisions at the hadronic
center-of-mass energy 2 TeV.


title: Supersymmetry Signatures with Tau Jets at the Tevatron

abstract:
  We study the supersymmetry reach of the Tevatron in channels containing both
isolated leptons and identified tau jets. In the most challenging case, where
the branching ratios of gauginos to taus dominate, we find that searches for
two leptons, a tau jet and a large amount of missing transverse energy have a
much better reach than the classic trilepton signature. With total integrated
luminosity of ${\rm L} \gsim 4 {\rm fb}^{-1}$, the Tevatron will start
extending the expected LEP-II reach for supersymmetry.


title: Early Inflation and Cosmology in Theories with Sub-Millimeter Dimensions

abstract:
  We discuss early cosmology in theories where the fundamental Planck mass is
close to the TeV scale. In such theories the standard model fields are
localized to a (3+1)-dimensional wall with n new transverse sub-millimeter
sized spatial dimensions. The topic touched upon include: early inflation that
occurs while the size of the new dimensions are still small, the spectrum and
magnitude of density perturbations, the post-inflation era of contraction of
our world while the internal dimensions evolve to their final ``large'' radius,
and the production of gravitons in the bulk during these two eras. The radion
moduli problem is also discussed.


title: Dijet Rapidity Gaps in Photoproduction from Perturbative QCD

abstract:
  By defining dijet rapidity gap events according to interjet energy flow, we
treat the photoproduction cross section of two high transverse momentum jets
with a large intermediate rapidity region as a factorizable quantity in
perturbative QCD. We show that logarithms of soft gluon energy in the interjet
region can be resummed to all orders in perturbation theory. The resummed cross
section depends on the eigenvalues of a set of soft anomalous dimension
matrices, specific to each underlying partonic process, and on the
decomposition of the scattering according to the possible patterns of hard
color flow. We present a detailed discussion of both. Finally, we evaluate
numerically the gap cross section and gap fraction and compare the results with
ZEUS data. In the limit of low gap energy, good agreement with experiment is
obtained.


title: Diffractive Physics at HERA

abstract: Brief review of the diffractive physics at HERA, stressing QCD aspects.


title: Contribution to $\epsilon'/\epsilon$ from anomalous gauge couplings

abstract:
  Recently KTev collaboration has measured $Re(\epsilon'/\epsilon) = (28\pm
4.1) \times 10^{-4}$ which is in agreement with early measurement from NA31.
The Standard Model prediction for $\epsilon'/\epsilon$ is on the lower end of
the experimentally allowed range depending on models for hadronic matrix
elements. In this paper we study the contributions from anomalous gauge
couplings. We find that the contributions from anomalous couplings can be
significant and can ehance $\epsilon'/\epsilon$ to have a value closer to data.


title:
On the Dominance of Statistical Fluctuation in the Factorial-Moment
  Study of Chaos in Low Multiplicity Events of High Energy Collisions

abstract:
  It is shown using Monte Carlo simulation that for low multiplicity events the
single-event factorial moments are saturated by the statistical fluctuations.
The diverse of the event-space moments $C_{p,q}$ of single-event moments with
the diminishing of phase space scale, called ``erraticity'', observed in
experiment can readily be reproduced by a flat probability distribution with
only statistical fluctuations and therefore does not indicate the existence of
chaos as suggested. The possibility of studying chaos in high multiplicity
events using erraticity analysis is discussed.


title:
Gribov Theory of Nuclear Interactions and Particle Densities at Future
  Heavy-Ion Colliders

abstract:
  Gribov approach to high-energy interactions of hadrons and nuclei is reviewed
and applied to calculation of particle production in heavy-ions collisions. It
is pointed out that the AGK (Abramovsky, Gribov, Kancheli) cutting rules is a
powerful tool to investigate particle spectra in these processes. It leads, in
the Glauber approximation, to a simple formula for the density of hadrons
produced in the central rapidity region in nucleus-nucleus interactions. An
estimate of this density for RHIC and LHC is presented and compared with
results of Monte-Carlo calculations. It is shown that the Glauber approximation
substantially overestimate particle densities compared to the results of the
complete Gribov theory. This is due to extra shadowing in the system, related
to large mass diffraction which leads to a strong decrease of particle
densities at mid rapidities. Our method of calculation of these effects has
been applied to the problem of shadowing of nuclear structure functions and a
good agreement with experimental data has been obtained.


title:
R-parity violating decays of the Top-Quark and the Top-Squark at the
  Tevatron

abstract:
  We study unconventional decays of the top-quark and the top-squark in the
framework of SUSY models with broken R-parity. The model under study is the
MSSM with an additional bilinear term that breaks R-parity. In this model the
top-squark behaves similar to a third generation leptoquark. We demonstrate
that existing Tevatron data on the top give rise to restrictions on the SUSY
parameter space. In particular, we focus on scenarios where the tau-neutrino
mass is smaller than 1 eV. We give an exclusion plot derived from the
leptoquark searches at Tevatron.


title: Diffractive Structure Function in a Quasi-Classical Approximation

abstract:
  We derive an expression for diffractive F_2 structure function which should
be valid at small x for quasi-elastic scattering on a hadron and for
quasi-elastic scattering on a large nucleus. This expression includes multiple
rescatterings of the quark-antiquark pair produced by the virtual photon off
the sources of color charge in a quasi-classical approximation. We find that
there is a relation between such diffractive production and inclusive
processes. In the former, one averages over all colors of sources before
squaring the amplitude, and in the latter one first squares the amplitude and
then averages it in the hadron's or nuclear wave function. We show that in the
limit of a large virtuality of the photon Q^2 the diffractive structure
function becomes linearly proportional to the gluon distribution of the hadron
or nucleus, therefore proving that in this sense diffraction is a leading twist
effect.


title: The Higgs mass bound in the SUSY multi-Higgs-doublet model

abstract:
  The upper bound on the mass of the lightest Higgs boson is provided in the
supersymmetric standard model with multi-Higgs doublets, up to two-loop order.
Relatively large corrections are expected from the experimentally unconstrained
extra Yukawa couplings. We calculate it including the two-loop leading-log
contributions as a function of the scale $\Lambda$, below which the theory
remains perturbative. Even for $\Lambda=10^{4}$ GeV, we obtain the upper bound
of 140 GeV, which is heavier than that of the MSSM by 10 GeV.


title: F_2^gamma at low Q^2 and sigma_{\gamma \gamma} at high energies

abstract:
  The parametrisation of the photon structure function in the low Q^2 region is
formulated. It includes the VMD contribution and the QCD improved parton model
component suitably extrapolated to the low Q^2 region. The parametrisation
describes reasonably well existing experimental data on sigma_{\gamma \gamma}
for real photons and the low Q^2 data on sigma_{\gamma^* \gamma}. Predictions
for sigma_{\gamma \gamma} and for sigma_{\gamma^* \gamma} for energies which
may be accesssible in future linear colliders are also given.


title:
Test of the Heavy Top Expansion in the Evaluation of MW and
  sin^2theta_eff

abstract:
  In order to test the accuracy of the Heavy Top-mass Expansion (HTE) employed
in recent two-loop calculations of MW and sin^2theta_eff, we consider their
contributions to subtracted quantities of the form MW_sub=MW(mh)-MW(mh0), where
mh0 is a reference point. The results are compared with those obtained by a
precise numerical evaluation of all the two-loop contributions involving both
the Higgs boson and a fermion loop. For the choice mh0=65 GeV, and over the
large range 65 GeV <mh< 1TeV, we find very small differences between the
precise and HTE calculations, amounting to |deltaMW|<0.8 MeV and |delta
s^2_eff|<1.2 x 10^-5. Although corrections involving light fermions are
necessary for the consistency and test of existent calculations, we also
discuss the separate contributions from the top-bottom isodoublet. In this
case, the differences are larger, although still small, namely |deltaMW|<1.9
MeV and |delta s^2_eff|< 4.5 x 10^-5.


title: The Pattern of Neutrino Masses and How to Determine It

abstract:
  Our knowledge of the neutrino sector of the Standard Model has recently
undergone a revolution. Deficits of the atmospheric muon neutrino flux and the
solar electron neutrino flux compared to their predicted values can be
understood in terms of neutrino oscillations and we can therefore infer that
neutrinos have non-degenerate masses. Additional but somewhat less secure
evidence for \bar\nu_\mu \to \bar\nu_e and \nu_\mu\to\nu_e oscillations has
been found in the LSND accelerator experiment. Because these experiments have
widely different L/E_\nu ranges (\approx 10 to 10^4 km/GeV for atmospheric,
\approx 10^{11} for solar, and \approx 1 for LSND), the mass-squared
differences required to explain the phenomena must be distinct. Given the
observations, an important next step is to deduce the pattern of neutrino
masses and mixings. Such studies depend on the number of neutrinos. The
invisible width of the Z-boson measured in LEP experiments gives N_\nu =
2.993\pm 0.011, consistent with the usual \nu_e, \nu_\mu and \nu_\tau "active"
neutrinos. But there may also be right-handed "sterile" neutrinos with no weak
interactions. Only the observation of oscillations of the active neutrinos to
sterile neutrinos can test for their existence. In the following, we first
discuss the atmospheric and solar neutrino data in a 3-neutrino framework and
then later generalize our considerations to include the LSND data with
oscillations of four neutrinos.


title: Spontaneous breaking of a global symmetry in a 331 model

abstract:
  In a 331 model in which the lepton masses arise from a scalar sextet it is
possible to break spontaneously a global symmetry implying in a pseudoscalar
majoron-like Goldstone boson. This majoron does not mix with any other scalar
fields and for this reason it does not couple, at the tree level, neither to
the charged leptons nor to the quarks. Moreover, its interaction with neutrinos
is diagonal. We also argue that there is a set of the parameters in which that
the model can be consistent with the invisible Z^0-width and that heavy
neutrinos can decay sufficiently rapid by majoron emission having a lifetime
shorter than the age of the universe.


title: Neutrino oscillations and mixings with three flavors

abstract:
  Global fits to all data of candidates for neutrino oscillations are presented
in the framework of a three-flavor model. The analysis excludes mass regions
where the MSW effect is important for the solar neutrino problem. The best fit
gives $\theta_1 \approx 28.9^\circ, \theta_2 \approx 4.2^\circ, \theta_3
\approx 45.0^\circ, m_2^2 - m_1^2 \approx 2.87 \cdot 10^{-4} eV^2$, and $m_3^2
- m_2^2 \approx 1.11 eV^2$ indicating essentially maximal mixing between the
two lightest neutrino mass eigenstates.


title:
Production of Like Sign Di-Leptons in p-p Collisions Through Composite
  Majorana Neutrinos

abstract:
  The production of Like-Sign-Di-leptons (LSD), in the high energy lepton
number violating ($\Delta L = +2$) reaction, p p --> 2jets + l+l+
(l=e,\mu,\tau) of interest for the experiments to be performed at the
forthcoming Large Hadron Collider (LHC), is investigated in detail, taking up a
composite model scenario in which the exchanged virtual composite neutrino is
assumed to be a Majorana particle that couples to the light leptons via the
$SU(2)\times U(1)$ gauge bosons through a magnetic type coupling
($\sigma_{\mu\nu}$). An helicity projection method is used to evaluate exactly
the tree-level amplitudes of the contributing parton subprocesses ($2\to 4$),
which allows to take into account all exchange diagrams and occurring
interferences. Numerical estimates of the corresponding signal cross-section
that implement kinematical cuts needed to suppress the Standard Model
background, are presented which show that in some regions of the parameter
space the total number of LSD events is well above the background. Assuming
non-observation of the LSD signal it is found that LHC would exclude a
composite Majorana neutrino up to 850 GeV (if one requires 10 events for
discovery). The sensitivity of LHC experiments to the parameter space is then
compared to that of the next generation of neutrinoless double beta decay
($\beta\beta_{0\nu}$) experiment, GENIUS, and it is shown that they will
provide constraints of the same order of magnitude and will play a
complementary role.


title: On the Interaction of Monopoles and Domain Walls

abstract:
  We study the interaction between monopoles and embedded domain walls in a
O(3) linear sigma model. We discover that there is an attractive force between
the monopole and the wall. We provide evidence that after the monopole and
domain wall collide, the monopole unwinds on the wall, and that the winding
number spreads out on the surface. These results support the suggestion by
Dvali et al. (hep-ph/9710301) that the monopole problem can be solved by
monopole-domain wall interactions.


title: Fast Evaluation of Feynman Diagrams

abstract:
  We develop a new representation for the integrals associated with Feynman
diagrams. This leads directly to a novel method for the numerical evaluation of
these integrals, which avoids the use of Monte Carlo techniques. Our approach
is based on based on the theory of generalized sinc ($\sin(x)/x$) functions,
from which we derive an approximation to the propagator that is expressed as an
infinite sum. When the propagators in the Feynman integrals are replaced with
the approximate form all integrals over internal momenta and vertices are
converted into Gaussians, which can be evaluated analytically. Performing the
Gaussians yields a multi-dimensional infinite sum which approximates the
corresponding Feynman integral. The difference between the exact result and
this approximation is set by an adjustable parameter, and can be made
arbitrarily small. We discuss the extraction of regularization independent
quantities and demonstrate, both in theory and practice, that these sums can be
evaluated quickly, even for third or fourth order diagrams. Lastly, we survey
strategies for numerically evaluating the multi-dimensional sums. We illustrate
the method with specific examples, including the the second order sunset
diagram from quartic scalar field theory, and several higher-order diagrams. In
this initial paper we focus upon scalar field theories in Euclidean spacetime,
but expect that this approach can be generalized to fields with spin.


title: Nine lectures on quark structure of light hadrons

abstract:
  The following lectures concern with the quark structure of hadrons made up
from light quarks. The symmetries of strong interaction were the only
instruments used for the description of this structure.
  The models of hadrons (there are a lot of them) were not considered. There
was not also considered the structure of hadrons with heavy quarks. The first
round of problems (models of hadrons) is not considered because of its
unexhaustability. The second round of problems (hadrons with heavy quarks) is
not considered because of the physics of heavy flavors tends mainly to
electroweak interaction and will be considered in the course of electroweak
interactions.
  Therefore, the presented here course, being the self-bounded part of the
theory of elementary particles, is considered separately.
  These lectures were formed from 1989 and are the part of the set of courses
on the theory of fundamental interactions for the students of Moscow Physical
Technical Institute. The basic source of the lectures was the unpublished
manuscript "Hadrons and quarks" by L.B. Okun. Another source was the "Lectures
on the theory of unitary symmetry in elementary particle physics" by Nguen Van
Hieu (Atomizdat, Moscow 1967). The list of references (due to its smallness) is
absent.


title: Stop and Sbottom Phenomenology in the MSSM

abstract:
  The first chapter serves as an introduction to the MSSM. I briefly review the
model and explain why stops and sbottoms provide an interesting playground for
exploring and testing this model. In the second chapter I discuss stop and
sbottom production at lepton colliders. I give the analytical formulae for the
production cross sections at e+e- and mu+mu- colliders including (general) beam
polarization. A numerical analysis shows the cross sections that can be
expected at LEP2, an e+e- Linear Collider, and a Muon Collider. In particular,
I address the topics of what can be gained by using polarized beams and how one
can determine the MSSM parameters by cross section measurements. The third
chapter is devoted to stop and sbottom decays including 1-loop SUSY-QCD
corrections. The calculations are done in the on-shell renormalization scheme
using dimensional reduction. I present the analytical formulae for the
\order(alpha_s) corrected decay widths and explain the subtleties that have to
be taken into account in the calculations. Moreover, I perform a detailed
numerical analysis of squark decay widths and branching ratios at tree level
and \order(alpha_s).


title:
Pauli Interference in the 't Hooft Model: Heavy Quark Expansion and
  Quark-Hadron Duality

abstract:
  Pauli Interference in decays of heavy flavor mesons, a genuinely nonleptonic
nonperturbative effect, is considered in the 't Hooft model. Analytic summation
of the exclusive decay widths yields the same expression as obtained in the
OPE-based approach. Threshold-related violations of local duality in PI are
found to be suppressed. A novel case is identified where the OPE effect is
completely saturated by a single final state.


title:
Motivation and detectability of an invisibly-decaying Higgs boson at the
  Fermilab Tevatron

abstract:
  A Higgs boson with mass below 150 GeV has a total decay width of less than 20
MeV into accessible Standard Model states. This narrow width means that the
usual branching fractions for such a light Higgs boson are highly susceptible
to any new particles to which it has unsuppressed couplings. In particular,
there are many reasonable and interesting theoretical ideas that naturally
imply an invisibly-decaying Higgs boson. The motivations include models with
light supersymmetric neutralinos, spontaneously broken lepton number,
radiatively generated neutrino masses, additional singlet scalar(s), or
right-handed neutrinos in the extra dimensions of TeV gravity. We discuss these
approaches to model building and their implications for Higgs boson
phenomenology in future Tevatron runs. We find, for example, that the Tevatron
with 30 fb^{-1} integrated luminosity can make a 3\sigma observation in the l+
l- plus missing transverse energy channel for a 125 GeV Higgs boson that is
produced with the same strength as the Standard Model Higgs boson but always
decays invisibly. We also analyze the b anti-b plus missing transverse energy
final state signal and conclude that it is not as sensitive, but it may assist
in excluding the possibility of an invisibly-decaying Higgs boson or enable
confirmation of an observed signal in the dilepton channel. We argue that a
comprehensive Higgs search at the Tevatron should include the possibility that
the Higgs boson decays invisibly.


title: Top quark production near threshold and the top quark mass

abstract:
  We consider top-anti-top production near threshold in $e^+ e^-$ collisions,
resumming Coulomb-enhanced corrections at next-to-next-to-leading order (NNLO).
We also sum potentially large logarithms of the small top quark velocity at the
next-to-leading logarithmic level using the renormalization group. The NNLO
correction to the cross section is large, and it leads to a significant
modification of the peak position and normalization. We demonstrate that an
accurate top quark mass determination is feasible if one abandons the
conventional pole mass scheme and if one uses a subtracted potential and the
corresponding mass definition. Significant uncertainties in the normalization
of the $t\bar{t}$ cross section, however, remain.


title: Sterile Neutrinos

abstract:
  A simultaneous understanding of the results of the LSND experiment indicating
$\nu_{\mu}-\nu_e$ oscillation together with other evidences for neutrino
oscillations from solar and atmospheric neutrino data seems to require the
existence of at least one sterile neutrino. One can also give other plausible
astrophysical arguments that seem to require light sterile neutrinos. A major
theoretical challenge posed by their existence is to understand why they are so
light. A scenario is presented where one assumes a parity doubling of the
standard model with identical matter and gauge content. The neutrinos of the
parity doubled (mirror) sector are light for the same reason that the known
neutrinos are light and since they do not couple to the known W and Z bosons,
they can be identified with the sterile neutrinos. Some of the implications and
possible tests of this hypothesis are mentioned.


title: Seasonal and Energy Dependence of Solar Neutrino Vacuum Oscillations

abstract:
  We make a global vacuum neutrino oscillation analysis of solar neutrino data,
including the seasonal and energy dependence of the recent Super-Kamiokande
708-day results. The best fit parameters for \nu_e oscillations to an active
neutrino are \delta m^2 = 4.42\times10^{-10} eV^2, \sin^2 2\theta = 0.93. The
allowed mixing angle region is consistent with bi-maximal mixing of three
neutrinos. Oscillations to a sterile neutrino are disfavored. Allowing an
enhanced hep neutrino flux does not significantly alter the oscillation
parameters.


title: Spikes in the Relic Graviton Background from Quintessential Inflation

abstract:
  The energy spectra of gravitational waves (GW) produced in quintessential
inflationary models increase in frequency and exhibit a sharp spike around 170
GHz where the associated fraction of critical energy density today stored in
relic gravitons is of the order of $10^{-6}$. We contrast our findings with the
spectra of ordinary inflationary models and we comment about possible
detetction strategies of the spike.


title: Low-Energy Parity-Violation and New Physics

abstract:
  The new physics sensitivity of a variety of low-energy parity-violating (PV)
observables is analyzed. A comparison is made between atomic PV for a single
isotope, atomic PV using isotope ratios, and PV electron-hadron and
electron-electron scattering. The complementarity among these observables, as
well as with high-energy processes, is emphasized. Theoretical uncertainties
entering the interpretation of low-energy measurements are discussed.


title: Quark-Antiquark-Gluon Jets in DIS Diffractive Dissociation

abstract:
  We study the diffractive production of $q\bar{q}g$ jets with large transverse
momenta in the region of large diffractive masses (small $\beta$). Cross
sections for transverse and longitudinal photons are obtained in the leading
log $1/x_{\fP}$ and log $1/\beta$ approximation, keeping all powers in log
$k_t^2/Q^2$. We perform a numerical study and illustrate the angular
distribution of the three jets. We also estimate the integrated diffractive
three jet cross section and compare with the dijet cross section obtained
before.


title: Exclusive, Hard Diffraction in QCD

abstract:
  In the first chapter we give an introduction to hard diffractive scattering
in QCD to introduce basic concepts and terminology. In the second chapter we
make predictions for the evolution of skewed parton distributions in a proton
in the LLA. We calculate the DGLAP-type evolution kernels in the LLA and solve
the skewed GLAP evolution equations with a modified version of the
CTEQ-package. In the third chapter, we discuss the algorithms used in the LO
evolution program for skewed parton distributions in the DGLAP region, discuss
the stability of the code and reproduce the LO diagonal evolution within less
than 0.5% of the original CTEQ-code. In chapter 4, we show that factorization
holds for the deeply virtual Compton scattering amplitude in QCD, up to power
suppressed terms, to all orders in perturbation theory. In chapter 5, we
demonstrate that perturbative QCD allows one to calculate the absolute cross
section of diffractive, exclusive production of photons (DVCS) at large $Q^2$
at HERA, while the aligned jet model allows one to estimate the cross section
for intermediate $Q^2 \sim 2 GeV^2$. We find a significant DVCS counting rate
for the current generation of experiments at HERA and a large azimuthal angle
asymmetry for HERA kinematics. In the last chapter, we propose a new
methodology of gaining shape fits to skewed parton distributions and, for the
first time, to determine the ratio of the real to imaginary part of the DIS
amplitude. We do this by using several recent fits to $F_2(x,Q^2)$ to compute
the asymmetry $A$ for the combined DVCS and Bethe-Heitler cross section. In the
appendix, we give an application of distributional methods as discussed
abstractly in chapter 4.


title: Soft Gluons in Logarithmic Summations

abstract:
  We demonstrate that all the known single- and double-logarithm summations for
a parton distribution function can be unified in the Collins-Soper resummation
technique by applying soft approximations appropriate in different kinematic
regions to real gluon emissions. Neglecting the gluon longitudinal momentum, we
obtain the $k_T$ (double-logarithm) resummation for two-scale QCD processes,
and the Balitsky-Fadin-Kuraev-Lipatov (single-logarithm) equation for one-scale
processes. Neglecting the transverse momentum, we obtain the threshold
(double-logarithm) resummation for two-scale processes, and the
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (single-logarithm) equation for
one-scale processes. If keeping the longitudinal and transverse momenta
simultaneously, we derive a unified resummation for large Bjorken variable $x$,
and a unified evolution equation appropriate for both intermediate and small
$x$.


title: Skewed Parton Distributions in Real and Virtual Compton Scattering

abstract:
  The handbag contribution to Compton scattering at moderately large momentum
transfer factorises into parton-photon subprocess amplitudes and new form
factors representing 1/x-moments of skewed parton distributions. A detailed
phenomenological study for polarised and unpolarised real and virtual Compton
scattering is presented


title:
Analytical solution of the relativistic Coulomb problem with a hard core
  interaction for a one-dimensional spinless Salpeter equation

abstract:
  In this paper, we construct an analytical solution of the one-dimensional
spinless Salpeter equation with a Coulomb potential supplemented by a hard core
interaction, which keeps the particle in the x positive region.


title: Supersymmetry and CP Violating Asymmetries in $B_{d,s}$ Decays

abstract:
  We study possible effects of supersymmetry (SUSY) in CP asymmetries in
non-leptonic $B_{d,s}$ decays in a variety of SUSY flavour models considered in
literature. We use both mass insertion and vertex mixing methods to calculate
squark-gluino box diagrams contribution to $B_{d,s} - \bar{B}_{d,s}$ mixings.
With the squark mixing parameter $\eta=0.22$, and with large new CP phases, it
turns out that the CP asymmetries to be measured in upcoming B-factories,
HERA-B and LHC-B, can be completely dominated by the SUSY contribution in
almost every considered model. Discrimination between the different models can
be done by comparing experimental results in different decay modes. In some
models squark masses up to $\sim 5$ TeV can be probed through these experiments
provided the SUSY contribution to $B - \bar{B}$ mixing is at 10% level,
$|M^{SUSY}_{12}/M_{12}^{SM}|\sim 0.1.$ This implies that models with heavy
squarks have a fair chance to be tested in the future CP experiments before
LHC.


title: Multipion coherent effects in high energy heavy-ion collisions

abstract:
  Multipion production in high energy nucleus-nucleus collisions is considered
in the model of the pion radiation by classical current. Strong coherent
effects of narrowing of pion longitudinal and transverse momenta distributions
are predicted at the RHIC energy. The coherence enhances the large
pseudorapidities producing the bump in the distribution. The growth of the
average pion multiplicity and the oscillation effect in the multiplicity
distribution are caused by the coherence as well.


title: Infrared Behaviour of the Gauge Boson Propagator in a Confining Theory

abstract:
  We study the gauge boson propagator in the dual Abelian Higgs theory which
confines electric charges. The confinement is due to dual
Abrikosov-Nielsen-Olesen strings. We show that the infrared double pole
1/(p^2)^2 in the propagator is absent due to the confinement phenomenon.
Instead, specific angular singularities signal the eventual set in of the
confinement. These angular singularities are a manifestation of the confining
strings.


title: Electron-Neutrino Majorana Mass and Solar Neutrino Oscillations

abstract:
  Assuming the Majorana masses of $\nu_e$ and the linear combination $c
\nu_\tau - s \nu_\mu$ to be equal from their couplings to a heavy scalar
triplet $\xi$, I show that their radiative splitting is given by $\Delta
m^2/m_\nu^2 = (3 c^2/4 \pi^2) (G_F/\sqrt 2) m_\tau^2 \ln (m_\xi^2/m_W^2)$. This
is applicable to the small-angle matter-enhanced oscillation solution of the
solar neutrino deficit and restricts $m_\nu$ to be between 0.20 and 0.36 eV if
$c^2 = 0.7$ and $m_\xi = 10^{14}$ GeV.


title: Electroweak Baryogenesis in the MSSM

abstract:
  We review the baryogenesis scenario in the MSSM at the perturbative level
and, in particular, the impact of two-loop corrections on the strength of the
phase transition and the amount of generated baryon asymmetry. We confirm the
baryogenesis window, where m_H is less than 115GeV, for m_Q less than a few
GeV, and the right-handed stop mass is constrained in the region between 100GeV
and the top mass. This scenario will be tested at LEP and Tevatron colliders.


title:
Effective Weak Chiral Lagrangian to ${\cal O} (p^4)$ in the Chiral Quark
  Model

abstract:
  We investigate the $\Delta S = 1,2$ effective weak chiral Lagrangian within
the framework of the chiral quark model. Starting from the effective four-quark
operators, we derive the effective weak chiral action by integrating out the
constituent quark fields. Employing the derivative expansion, we obtain the
effective weak chiral Lagrangian to order ${\cal O} (p^4)$. We examine the
contributions of the order ${\cal O} (N_c)$ to the ratio
$g_{\underline{8}}/g_{\underline{27}}$, considering e.g. the quark axial-vector
constant $g_{\rm A}$ different from unity. The low energy constants of the
counterterms are also presented and discussed.


title: Transitional CP Violation in the MSSM and Electroweak Baryogenesis

abstract:
  Electroweak baryogenesis depends on the profile of the bubble wall created in
the first-order phase transition. It is pointed out that CP violation in the
Higgs sector of the MSSM could become large enough to explain the baryon
asymmetry. We confirm this by solving the equations of motion for the Higgs
fields with the effective potential at the transition temperature. That is, we
present an example such that the transitional CP violation is realized and show
the possibility that the baryon asymmetry of the universe may be produced, if
marginally, by the $\tau$ lepton interacting with the wall, when an explicit CP
breaking in the Higgs sector, which is consistent with experimental bounds, is
induced at the phase transition.


title:
The Influence of Statistical Fluctuations on Erraticity Behavior of
  Multiparticle System

abstract:
  It is demonstrated that in low multiplicity sample, the increase of the
fluctuation of event-factorial-moments with the diminishing of phase space
scale, called ``erraticity'', are dominated by the statistical fluctuations.
The erraticity behavior observed at NA27 experiment can be readily reproduced
by pure statistical fluctuations. Applying erraticity analysis to a high
multiplicity sample is recommended and the method is improved at very high
multiplicity case as well.


title: Dark Matter in Models of String Cosmology

abstract:
  The origin of dark matter in the universe may be weakly interacting scalar
particles produced by amplification of quantum fluctuations during a period of
dilaton-driven inflation. We present two interesting cases, the case of small
fluctuations, and the resulting nonthermal spectrum, and the case of large
fluctuations of a field with a periodic potential, the QCD axion.


title: Pomeron Fusion and Central $\eta$ and $\eta'$ Meson Production

abstract:
  The contribution of pomeron fusion to the cross section of $\eta$ and $\eta'$
productions in double-diffractive scattering has been calculated within the
Donnachie-Landshoff model of pomeron. It is shown that the double pomeron
exchange mechanism does not explain the full set of the recent data of WA102
Collaboration, though it might not be inconsistent with $\eta'$ productions.


title:
Chi_2 production in polarized pp collisions at RHIC: measuring \Delta G
  and testing the color octet model

abstract:
  We consider the production and decay of the $\chi_2$ charmonium state in
polarized and unpolarized $pp$ collisions at RHIC in the framework of an
effective theory based on the QCD multipole expansion. We find that the angular
distribution in the decay of the produced charmonium, $\chi_2 \to J/\psi +
\gamma$, in the unpolarized case allows us to distinguish clearly between the
color singlet and color octet production mechanisms. Once the production
mechanism is known, the angular distribution in the polarized case can be used
to measure the polarized gluon distribution in the proton, $\Delta G(x)$.


title:
QCD condensate contributions to the effective quark potential in a
  covariant gauge

abstract:
  We discuss QCD condensate contributions to the gluon propagator both in the
fixed-point gauge and in covariant gauges for the external QCD vacuum gluon
fields with the conclusion that a covariant gauge is essential to obtain a
gauge invariant QCD vacuum energy density difference and to retain the
unitarity of the quark scattering amplitude. The gauge-invariant QCD condensate
contributions to the effective one-gluon exchange potential are evaluated by
using the effective gluon propagator which produces a gauge-independent quark
scattering amplitude.


title:
Global QCD Analysis of Parton Structure of the Nucleon: CTEQ5 Parton
  Distributions

abstract:
  An up-to-date global QCD analysis of high energy lepton-hadron and
hadron-hadron interactions is performed to better determine the gluon and quark
parton distributions in the nucleon. Improved experimental data on inclusive
jet production, in conjunction with precise deep inelastic scattering data,
place good constraints on the gluon over a wide range of x; while new data on
asymmetries in Drell-Yan processes contribute to better determine the d/u
ratio. Comparisons with results of other recent global analyses are made, and
the differences are described. Open issues and the general problem of
determining the uncertainties of parton distributions are discussed.


title: SO(10) GUTs with gauge mediated supersymmetry breaking

abstract:
  We explore the phenomenology of supersymmetric SO(10) grand unified theories
with gauge mediated supersymmetry breaking. We show that if SO(10) breaking
proceeds through intermediate left-right symmetric gauge groups which are
broken at the supersymmetry breaking scale, then perturbative unification
allows the existence of only a few consistent models with very similar
phenomenological consequences. We list and discuss some distinctive signatures
of these theories. The most remarkable feature of the class of theories
introduced here is that, unlike in models with simpler symmetry breaking
chains, the allowed messenger spectrum is practically unique.


title:
The CP-conserving contribution to the transverse muon polarization in K+
  -> mu+ nu gamma

abstract:
  We present a detailed estimate of the transverse muon polarization (P_T) due
to electromagnetic final-state interactions in the decay $K^+ \to \mu^+ \nu
\gamma$. This CP-conserving effect represents the dominant contribution to P_T
within the Standard Model. As a result of an explicit calculation, we find that
the CP-conserving contribution to P_T is quite small, typically of
$\cO(10^{-4})$, essentially due to the suppression factor $\alpha/4\pi^2$. This
enforces the sensitivity of P_T in probing extensions of the Standard Model
with new sources of time-reversal violations. A brief discussion about possible
CP-violating contributions to P_T in the framework of supersymmetric models
with unbroken R-parity is also presented.


title: Baryon form factors

abstract:
  We calculate the form factors of the baryon octet in the framework of heavy
baryon chiral perturbation theory. The calculated charge radius of the
$\Sigma^-$ is in agreement with recent measurements from CERN and Fermilab. We
show that kaon loop effects can play a significant role in the neutron electric
form factor. Furthermore. we derive generalized Caldi-Pagels relations between
various charge radii which are free of chiral loop effects.


title: Flatons and Peccei-Quinn Symmetry

abstract:
  We study in detail a supersymmetric Peccei-Quinn model, which has a DFSZ and
a KSVZ version. The fields breaking the Peccei-Quinn (PQ) symmetry correspond
to flat directions (flaton fields) and have unsuppressed couplings when PQ
symmetry is unbroken. The models have interesting particle physics
phenomenology. The PQ scale is naturally generated through radiative
corrections; also, in the DFSZ case the $\mu$ problem can be solved and
neutrino masses can be generated. Cosmologically they lead to a short period of
thermal inflation making the axion an excellent dark matter candidate if one of
the flaton fields has a positive effective mass-squared at early times but with
too low a density in the opposite case.
  A highly relativistic population of axions is produced by flaton decay during
the subsequent reheating, whose density is constrained by nucleosynthesis. We
evaluate all of the relevant reaction rates and evaluate the nucleosynthesis
constraint. We find that the KSVZ model is practically ruled out, while the
DFSZ model has a sizable allowed region of parameter space.


title: Composite Two-Higgs Models and Chiral Symmetry Restoration

abstract:
  The effective quark models with quasilocal interaction are used for
description of two composite Higgs doublets, in strong coupling (tricritical)
regime below the compositeness scale \Lambda_{C}. The low energy effective
action of Two-Higgs Doublet Standard Model (2HD SM) is obtained in the large
N_c and large-log approximation. The two-point correlators of scalar and
pseudoscalar Higgs fields are derived for investigation of how the chiral
symmetry is broken. The comparison of their asymptotics at high energies allows
to realize the chiral symmetry restoration characteristic for the QCD-like
models and thereby to make hints on the existence of new physical phenomena in
the TeV energy region.


title: Pionic Parton Distributions Revisited

abstract:
  Using constituent quark model constraints we calculate the gluon and
sea-quark content of pions solely in terms of their valence density (fixed by
\pi N Drell-Yan data) and the known sea and gluon distributions of the nucleon,
using the most recent updated valence-like input parton densities of the
nucleon. The resulting small-x dynamical QCD predictions for g^{\pi}(x,Q^2) and
\bar{q}^{\pi}(x,Q^2) are unique and parameter free. Simple analytic
parametrizations of the resulting parton distributions of the pion are
presented in LO and NLO. These results and parametrizations will be important,
among other things, for updated formulations of the parton distributions of
real and virtual photons.


title:
Mass bounds of the lightest CP-even Higgs boson in the two-Higgs-doublet
  model

abstract:
  The upper and the lower bounds of the lightest CP-even Higgs-boson mass
($m_h$) are discussed in the two-Higgs-doublet model (2HDM) with a
softly-broken discrete symmetry. They are obtained as a function of a cut-off
scale $\Lambda$ ($\leq 10^{19}$ GeV) by imposing the conditions in which the
running coupling constants neither blow up nor fall down below $\Lambda$. In
comparison with the standard model (SM), although the upper bound does not
change very much, the lower bound is considerably reduced. In the decoupling
regime where only one Higgs boson ($h$) becomes much lighter than the others,
the lower bound is given, for example, by about 100 GeV for $\Lambda = 10^{19}$
GeV and $m_t = 175$ GeV, which is smaller by about 40 GeV than the
corresponding lower bound in the SM. In generic cases, $m_h$ is no longer
bounded from below by these conditions. If we consider the $b \to s \gamma$
constraint, small values of $m_h$ are excluded in Model II of the 2HDM.


title:
Theoretical Determination of the $\Delta N\gamma $ Electromagnetic
  Transition Amplitudes in the $\Delta (1232)$ Region

abstract:
  We utilize non-perturbative and fully relativistic methods to calculate
the\thinspace \thinspace $\Delta N\gamma $ electromagnetic transition
amplitudes $G_{M}^{*}(q^{2})$ (related to the magnetic dipole moment $%
M_{1^{+}}^{3/2}(q^{2})$), $G_{E}^{*}(q^{2})$ (related to the electric
quadrupole moment $E_{1^{+}}^{3/2}(q^{2})$), the electromagnetic ratio $%
R_{EM}(q^{2})\equiv
-G_{E}^{*}(q^{2})/G_{M}^{*}(q^{2})=E_{1^{+}}^{3/2}(q^{2})/M_{1^{+}}^{3/2}(q^{2}
) $, and discuss their $q^{2}$ behavior in the $\Delta (1232)$ mass region.
These are very important quantities which arise in all viable quark, QCD, or
perturbative QCD models of pion electroproduction and photoproduction.


title:
Stochastic dynamics of correlations in quantum field theory: From
  Schwinger-Dyson to Boltzmann-Langevin equation

abstract:
  The aim of this paper is two-fold: in probing the statistical mechanical
properties of interacting quantum fields, and in providing a field theoretical
justification for a stochastic source term in the Boltzmann equation. We start
with the formulation of quantum field theory in terms of the Schwinger - Dyson
equations for the correlation functions, which we describe by a
closed-time-path master ($n = \infty PI$) effective action. When the hierarchy
is truncated, one obtains the ordinary closed-system of correlation functions
up to a certain order, and from the nPI effective action, a set of
time-reversal invariant equations of motion. But when the effect of the higher
order correlation functions is included (through e.g., causal factorization--
molecular chaos -- conditions, which we call 'slaving'), in the form of a
correlation noise, the dynamics of the lower order correlations shows
dissipative features, as familiar in the field-theory version of Boltzmann
equation. We show that fluctuation-dissipation relations exist for such
effectively open systems, and use them to show that such a stochastic term,
which explicitly introduces quantum fluctuations on the lower order correlation
functions, necessarily accompanies the dissipative term, thus leading to a
Boltzmann-Langevin equation which depicts both the dissipative and stochastic
dynamics of correlation functions in quantum field theory.