title: Chiral Disorder and QCD Phase Transitions

abstract:
  If QCD is to undergo a second order phase transition, the light quark return
probability is universal for large times at the critical point. We show that
this behavior is distinct from the one expected at the mobility edge of a
metal-insulator transition or a percolation transition in d$\leq 4$. Our
results are accessible to current lattice QCD simulations.


title: Mass Hierarchies, Hidden Symmetry and Maximal CP-Violation

abstract:
  In view of the observed strong hierarchy of the quark and lepton masses and
of the flavor mixing angles it is argued that the description of flavor mixing
must take this into account. One particular interesting way to describe the
flavor mixing, which, however, is not the one used today, emerges, which is
particularly suited for models of quark mass matrices based on flavor
symmetries. We conclude that the unitarity triangle important for B physics
should be close to or identical to a rectangular triangle. CP violation is
maximal in this sense.


title: Composite model with neutrino large mixing

abstract:
  We suggest a simple composite model that induces the large flavor mixing of
neutrino in the supersymmetric theory. This model has only one hyper-color in
addition to the standard gauge group, which makes composite states of preons.
In this model, {\bf 10} and {\bf 1} representations in SU(5) grand unified
theory are composite states and produce the mass hierarchy. This explains why
the large mixing is realized in the lepton sector, while the small mixing is
realized in the quark sector. This model can naturally solve the atmospheric
neutrino problem. We can also solve the solar neutrino problem by improving the
model.


title:
Cosmology with non-minimal scalar field: graceful entrance into
  inflation

abstract:
  We propose a scenario of the beginning of inflation in which the non-vacuum
value of the scalar field that drives inflation develops dynamically due to the
non-minimal coupling to gravity. In this scenario, inflation emerges as an
intermediate stage of the evolution of the Universe, well after the Planck
epoch, from a fairly general initial state.


title: Re-assessing the anomalous J/psi-suppression in the CERN NA50 data

abstract:
  A systematic analysis of the L-dependence of the J/psi-suppression in the
data of the CERN NA38 and NA50 experiments shows that the anomalous suppression
in the 1995 Pb-Pb data is at best a 4$\sigma$ effect at any of the L-values for
the Pb-Pb data, where L is the geometrical mean path length of the J/psi in the
colliding nuclei. Possible implications for the 1996 data are discussed.


title: Elementary Atom Interaction with Matter

abstract:
  The calculations of the elementary atom (the Coulomb bound state of
elementary particles) interaction with the atom of matter, which are performed
in the Born approximation, are reviewed. We first discuss the nonrelativistic
approach and then its relativistic generalization. The cross section of the
elementary atom excitation and ionization as well as the total cross section
are considered. A specific selection rule, which applies for the atom formed as
positronium by particle-antiparticle pair, is analyzed.


title: First-Order QCD Effects in t-tbar Production at the NLC Above Threshold

abstract:
  We study the effects of gluon interference in the production and
semi-leptonic decay of a t-tbar pair above threshold at the Next Linear
Collider (NLC). We calculate all matrix elements to next-to-leading order and
use the resulting expressions for the development of a Monte Carlo event
generator. Our results show effects at the level of 10% in differential
cross-sections. We thus extend previous results obtained by analytical means in
the soft-gluon limit.


title: Baryon Asymmetry, Neutrino Mixing and Supersymmetric SO(10) Unification

abstract:
  The baryon asymmetry of the universe can be explained by the
out-of-equilibrium decays of heavy right-handed neutrinos. We analyse this
mechanism in the framework of a supersymmetric extension of the Standard Model
and show that lepton number violating scatterings are indispensable for
baryogenesis, even though they may wash-out a generated asymmetry. By assuming
a similar pattern of mixings and masses for neutrinos and up-type quarks, as
suggested by SO(10) unification, we can generate the observed baryon asymmetry
without any fine tuning, if (B-L) is broken at the unification scale
\Lambda_{GUT}\sim 10^{16} GeV and, if m_{\nu_\mu} \sim 3\cdot 10^{-3} eV as
preferred by the MSW solution to the solar neutrino deficit.


title: Loop-induced SUSY Effects in Strong Top Pair Production

abstract:
  We present some results of the calculation of MSSM one-loop contributions to
strong $t \bar t$ production in hadronic collisions. Here we concentrate on the
MSSM electroweak-like O(\alpha) and SQCD O(\alpha_s) corrections to the main
production mechanism at the Fermilab Tevatron $p \bar p$ collider, $q\bar q\to
g \to t \bar t$. We give results for the total $t \bar t$ production rate and
for parity violating asymmetries in the production of left and right handed top
quark pairs.


title:
Quantum Groups as Flavor Symmetries: Account of Nonpolynomial
  SU(3)-Breaking Effects in Baryon Masses

abstract:
  The use, for flavor symmetries, of the quantum (or q-) analogs of unitary
groups SU(n_f) yields new, very accurate, baryon mass sum rules. We show, in
the 3-flavor case, that such approach accounts for nonpolynomial SU(3)-breaking
effects in the octet and decuplet baryon masses. A version of this approach
with manifestly q-covariant mass operator is given. The obtained new version of
the q-deformed mass relation is simpler than those derived before, but, for its
empirical validity, the parameter q is to be fixed by fitting. As shown, the
well-known Gell-Mann--Okubo octet mass sum rule results, besides usual SU(3),
also from an exotic "symmetry" encoded in the singular case q=-1 of the
q-algebra U_q(su_3).


title:
Probing the Nucleon's Transversity Via Two-Meson Production in Polarized
  Nucleon-Nucleon Collisions

abstract:
  We explore the possibility of probing the nucleon's transversity distribution
$\delta q(x)$ through the final state interaction between two mesons
($\pi^+\pi^-$, $\pi K$, or $K\bar K$) produced in transversely polarized
nucleon-nucleon collisions. We present a single spin asymmetry and estimate its
magnitude under some assumptions for the transversity distribution function and
the unknown interference fragmentation function.


title: New Axial Interactions at a TeV

abstract:
  We consider a heavy fourth family with masses lying in the symmetry breaking
channel of a new strong gauge interaction. This interaction generates a heavy
quark axial-type operator, whose effects can be enhanced through multiple
insertions. In terms of the strength of this operator we can express new
negative contributions to the S and T parameters and the shifts of the Z
couplings to the third family. In particular we find that the new contribution
to T is strongly constrained by the experimental constraints on the Z coupling
to the tau.


title:
Virtual Compton Scattering--Generalized Polarizabilities of Nucleons and
  Pions

abstract:
  Virtual Compton scattering off nucleons and pions at low energies is
discussed.
  Predictions for the generalized polarizabilities of the nucleon are presented
within the framework of heavy-baryon chiral perturbation theory and the linear
sigma model.
  First results for the generalized polarizabilities of the charged pion in
chiral perturbation theory at ${\cal O}(p^4)$ are shown.


title: Glue constraining asymmetries in W, $\gamma$ or Z production at CERN LHC

abstract:
  We propose a class of forward-backward asymmetries with respect to the
subprocess c.m. scattering angle in $V$+jet production at hadron colliders,
with V being any of (W, Z, $\gamma$, H), which are directly proportional to the
gluon distribution $g(x)$. The informations that these asymmetries can provide
are complementary of those reachable from measurements of the transverse
momentum and/or the rapidity distributions of a $V$ in kinematical regimes
where gluon scattering subprocesses dominate. The accuracy which can be reached
in the W, Z and $\gamma $ cases, at the upgraded Tevatron and at LHC, should
allow a considerable improvement of our knowledge of the gluon distribution
function, especially at large x.


title:
The Derivation of Deser's Formula and Electromagnetic Corrections to the
  Pionium Life Time

abstract:
  We give the modern derivation of Deser's formula using analytic continuation
of the scattering amplitude as a function of momentum. The electromagnetic
corrections to the pionium lifetime are given as evaluated in a potential
model.


title: Automatized One-Loop Calculations in 4 and D dimensions

abstract:
  Two program packages are presented for evaluating one-loop amplitudes. They
can work either in dimensional regularization or in constrained differential
renormalization. The latter method is found at the one-loop level to be
equivalent to regularization by dimensional reduction.


title: Aspects of Higgs Boson Searches at LEP2

abstract:
  A preliminary combined mass limit of about 90 GeV has been reported for the
Minimal Standard Model Higgs boson from the 183 GeV data taken in 1997, with a
total luminosity of about 200 pb-1. Similar mass limits have been reported from
the individual LEP experiments based on the first 1998 data at 189 GeV with up
to 40 pb-1 each. For the first time the LEP experiments have made a common
effort to derive preliminary combined limits in the Minimal Supersymmetric
extension of the Standard Model. For three MSSM benchmark parameter sets, mass
limits for the lighter scalar of 77 GeV and for the pseudoscalar of 78 GeV have
been derived. In a more general parameter scan unexcluded mass regions have
been revealed. An independent variation of the SUSY parameters results in
cancellation effects of production cross sections and thus some parameter
regions are not excluded in this more general framework. Direct and indirect
limits from other SUSY particle searches have been taken into account.


title: Field strength correlators in QCD: new fits to the lattice data

abstract:
  We discuss the results obtained by fitting the lattice data of the
gauge-invariant field strength correlators in QCD with some particular
functions which are commonly used in the literature in some phenomenological
approaches to high-energy hadron-hadron scattering. A comparison is done with
the results obtained in the original fits to the lattice data.


title: Neutrino mass spectrum and mixing from neutrino oscillation data

abstract:
  Two schemes of mixing of four massive neutrinos with two close neutrino
masses separated by a gap of Delta m^2 about 1 eV^2 can accommodate solar,
atmospheric and LSND neutrino oscillation data. It is shown that long-baseline
nu(e)->nu(x) and nu(mu)->nu(e) transitions are strongly suppressed in these
schemes. The scheme of mixing of three massive neutrinos with a mass hierarchy
that can describe solar and atmospheric data is also discussed. It is shown
that in this scheme the effective Majorana mass that characterizes the matrix
element of neutrinoless double-beta decay is smaller than about 10^{-2} eV.


title: Four-neutrino mixing, oscillations and BBN

abstract:
  We investigate the implications for neutrino mixing implied by the results of
all neutrino oscillation experiments and by the standard Big-Bang
Nucleosynthesis constraint on the number of light neutrinos.


title: A new approach to multi-jet calculations in hadron collisions

abstract:
  We present an algorithm to evaluate the exact, tree-level matrix elements for
multi-parton processes in QCD. We tested this technique, based on the recursive
evaluation of the S-matrix, on processes such as gg -> n gluons and q qbar -> n
gluons, with n up to 9. The summation over colour configurations is designed to
allow the construction of parton-level event generators suitable to interfacing
with a parton-shower evolution including the effects of colour-coherence. This
leads to a fully exclusive, hadron-level description of multi-jet final states,
accurately incorporating the dynamics of large jet-jet separation angles.
Explicit results for the total rates and differential distributions of
processes with 8 final-state partons are given.


title:
Signatures of Gauge Mediated Supersymmetry Breaking Models at the
  Tevatron

abstract:
  We consider the scenarios of the GMSB models in which the dominant signal for
supersymmetry at the Tevatron are the events having two or three $\tau$ leptons
with high $p_T$ accompanied by large missing transverse energy. This signal is
very different from the multijet or multileptons (involving $e$ and/or $\mu$
only) in the usual supergravity models or the photonic signals in the GMSB
models (where the lightest neutralino is the next to lightest supersymmetric
particle (NLSP)). The parameter space where the lighter stau is the NLSP allows
this possibility. We find that such a signal could be observable at the
Tevatron Run II.


title: A Semianalytical Method to Evolve Parton Distributions

abstract:
  We present a new method to solve in a semianalytical way the
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations at NLO order in
the x-space. The method allows to construct an evolution operator expressed in
form of a rapidly convergent series of matrices, depending only on the
splitting functions. This operator, acting on a generic initial distribution,
provides a very accurate solution in a short computer time (only a few
hundredth of second). As an example, we apply the method, useful to solve a
wide class of systems of integrodifferential equations, to the polarized parton
distributions.


title: Why e+ e- to T Tbar is Different

abstract:
  Unlike other examples of fermion pair production in e+ e- collisions, we show
that top-quark pairs are produced in an essentially unique spin configuration
in polarized e+ e- colliders at all energies. Since the directions of the
electroweak decay products of polarized top-quarks are strongly correlated to
the top-quark spin axis, this unique spin configuration leads to a distinctive
topology for top-quark pair events which can be used to constrain anomalous
couplings to the top-quark. A significant interference effect between the
longitudinal and transverse W-bosons in the decay of polarized top-quarks is
also discussed.


title: Polarized Parton Distributiions and Light-Front Dynamics

abstract:
  We present a consistent calculation of the structure functions within a
light-front constituent quark model of the nucleon. Relativistic effects and
the relevance of the covariance constraints are analyzed for both polarized and
unpolarized parton distributions. Various models, which differ in their gluonic
structure at the hadronic scale, are investigated. The results of the full
covariant calculation are compared with those of a non-relativistic
approximation to show the structure and magnitude of the differences.


title: The Quark Orbital Angular Momentum in a Light-Cone Representation

abstract:
  We perform an analysis of the quark angular momentum in a light-cone
representation by taking into account the effect due to the Melosh-Wigner
rotation and find that there is a relativistic correction factor connecting the
quark orbital angular momentum with the quark model spin distribution:
$L_q(x)={<M_L(x)>}\Delta q_{QM}(x)$. The quark orbital angular momentum
$L_q(x)$ and the quark helicity distribution $\Delta q(x)$ are connected to the
quark model spin distribution $\Delta q_{QM}(x)$ by a relation:
$\frac{1}{2}\Delta q(x)+ L_q(x)=\frac{1}{2}\Delta q_{QM}(x)$, which means that
one can decompose the quark model spin contribution $\Delta q_{QM}(x)$ by a
quark helicity term $\Delta q(x)$ {\it plus} an orbital angular momentum term
$L_q(x)$. There is also a new relation connecting the quark orbital angular
momentum with the measurable quark helicity distribution and transversity
distribution ($\delta q(x)$): $\Delta q(x)+L_q(x)=\delta q(x)$, from which we
may have new sum rules connecting the quark orbital angular momentum with the
nucleon axial and tensor charges.


title: Update on Atmospheric Neutrinos

abstract:
  I summarize here the results of a global fit to the full data set
corresponding to 535 days of data of the Super-Kamiokande experiment as well as
to all other experiments in order to compare the two most likely solutions to
the atmospheric neutrino anomaly in terms of oscillations in the $\nu_\mu \to
\nu_\tau$ and $\nu_\mu \to \nu_s$ channels.


title: Does Inflationary Particle Production suggest Omega_m < 1?

abstract:
  We study a class of FRW spacetimes with a nonminimally coupled light massive
scalar field. Values of the coupling parameter xi<0 enhance long range power in
the vacuum expectation value of the energy-momentum tensor and fundamentally
alter the nature of inflationary particle production: the energy density of
created particles behaves like an effective cosmological constant, leading
generically to Omega_m < 1 in clustered matter and providing a possible
resolution of the ``Omega problem'' for low density cosmological models.


title:
Super-Kamiokande atmospheric neutrino data, zenith distributions, and
  three-flavor oscillations

abstract:
  We present a detailed analysis of the zenith angle distributions of
atmospheric neutrino events observed in the Super-Kamiokande (SK) underground
experiment, assuming two-flavor and three-flavor oscillations (with one
dominant mass scale) among active neutrinos. In particular, we calculate the
five angular distributions associated to sub-GeV and multi-GeV \mu-like and
e-like events and to upward through-going muons, for a total of 30 accurately
computed observables (zenith bins). First we study how such observables vary
with the oscillation parameters, and then we perform a fit to the experimental
data as measured in SK for an exposure of 33 kTy (535 days). In the two-flavor
mixing case, we confirm the results of the SK Collaboration analysis, namely,
that \nu_\mu<--->\nu_\tau oscillations are preferred over \nu_\mu<--->\nu_e,
and that the no oscillation case is excluded with high confidence. In the
three-flavor mixing case, we perform our analysis with and without the
additional constraints imposed by the CHOOZ reactor experiment. In both cases,
the analysis favors a dominance of the \nu_\mu<--->\nu_\tau channel. Without
the CHOOZ constraints, the amplitudes of the subdominant \nu_\mu<--->nu_e and
\nu_e<--->\nu_\tau transitions can also be relatively large, indicating that,
at present, current SK data do not exclude sizable \nu_e mixing by themselves.
After combining the CHOOZ and SK data, the amplitudes of the subdominant
transitions are constrained to be smaller, but they can still play a
nonnegligible role both in atmospheric and other neutrino oscillation searches.
In particular, we find that the \nu_e appearance probability expected in long
baseline experiments can reach the testable level of ~15%.


title:
The Model for QCD Running Coupling Constant with Dynamically Generated
  Mass and Enhancement in the Infrared Region

abstract:
  Nonperturbative studies of the strong running coupling constant in the
infrared region are discussed. Starting from the analyses of the Dyson --
Schwinger equations in the gauge sector of QCD, the conclusion is made on an
incomplete fixing of the perturbation theory summation ambiguity within
"(forced) analytization procedure" (called also a dispersive approach). A
minimal model for $\bar\alpha_s(q^2)$ is proposed so that the perturbative
time-like discontinuity is preserved and nonperturbative terms not only remove
the Landau singularity but also provide the ultraviolet convergence of the
gluon condensate. Within this model, on the one hand, the gluon zero modes are
enhanced (the dual superconductor property of the QCD vacuum) and, on the other
hand, dynamical gluon mass generation is realized, with $m_g$ estimated as $0.6
GeV$. The uncertainty connected with the division into perturbative and
nonperturbative contributions is discussed with the gluon condensate taken as
an example.


title:
Two hypothetic sterile neutrinos which want to mix with $\nu_e $ and
  $\nu_\mu $

abstract:
  It is argued that the observed deficit of solar and atmospheric neutrinos can
be explained by neutrino oscillations $\nu_e \to \nu_s $ and $\nu_\mu \to
\nu'_{s}$ involving two hypothetic sterile neutrinos $\nu_s $ and $\nu'_{s} $
(blind to all Standard--Model interactions). They are keen to mix nearly
maximally with $\nu_{e}$ and $\nu_{\mu}$, respectively, to form neutrino mass
states $\nu_1$, $\nu_4 $ and $\nu_2 $, $\nu_5 $. Our argument is presented in
the framework of a model of fermion "texture" formulated previously, which
implies the existence of two sterile neutrinos beside the three conventional.


title:
Quantum mechanics of confinement and chiral symmetry breaking in
  two-dimensional QCD

abstract:
  The system of light quark and heavy anti-quark source is studied in 1+1 QCD
in the large $N_C$ limit. Making use of the modified Fock-Schwinger gauge
allows to consider simultaneously the spectroscopical problem of the q\bar Q
bound states and the problem of the light quark Green function. The Dirac-type
equation for the spectrum of the system is proved to be equivalent to the
well-known 't Hooft one in the one body limit. The unitary transformation from
the Dirac-Pauli representation to the Foldy-Wouthuysen one is carried out
explicitly, and it is shown that the equation in the Foldy-Wouthuysen
representation can be treated as a gap equation which defines the light quark
self-energy in the modified Fock-Schwinger gauge. The Foldy--Wouthuysen angle
is found to play the role of the Bogoliubov-Valatin one and to give the
standard value of the chiral condensate. Connections of the given formalism to
the standard four-dimensional QCD are outlined and discussed.


title: Pion-pion interaction at low energy

abstract:
  A brief discussion of the elastic pion-pion scattering amplitude to two loops
in chiral perturbation theory is given. Some technical details of the
evaluation of two-loop diagrams are addressed, and results relevant for the
pionium decay are presented.


title:
Eta-prime quark-antiquark and eta-prime NN vertex suppression in
  effective theories

abstract:
  In an effective theory containing only quark degrees of freedom, such as the
extended Nambu-Jona-Lasinio model, the influence of the axial anomaly can be
incorporated by a self-interaction of the 't Hooft determinant type.
  I will show that despite the theshold problem related to the eta-prime meson
this leads to a significant suppression of the eta-prime coupling g_{\eta' q
\bar{q}} to dynamical quarks which suggests a suppression of the eta-prime-NN
vertex as compared to the eta-NN vertex.


title: High energy photon-neutrino interactions

abstract:
  A general decomposition of the amplitudes for the $2\to 2$ processes
$\gamma\nu\to\gamma\nu$ and $\gamma\gamma\to\nu\bar{\nu}$ is obtained using
gauge invariance and Bose symmetry. The restrictions implied by this
decomposition are investigated for the reaction $\gamma\gamma\to\nu\bar{\nu}$
by computing the one-loop helicity amplitudes in the standard model. In the
center of mass, where $\sqrt{s} = 2\omega$, the cross section grows roughly as
$\omega^6$ up to the threshold for $W$-boson production, $\sqrt{s} = 2m_W$.
Astrophysical implications of very high energy photon-neutrino interactions are
discussed.


title: Indirect CP Violation in the Bd-system

abstract:
  Recently a rephasing invariant definition of the CP-mixing parameter for
Indirect CP Violation has been introduced. This is made possible by the
explicit use of the CP operator into the analysis. The problem is then that of
the determination of the CP operator for a CP violating scenario. We discuss it
and provide a definite solution.


title:
Leading Charm in Hadron-Nucleus Interactions in the Intrinsic Charm
  Model

abstract:
  Leading charm hadrons produced in hadron-nucleus interactions cannot be
adequately described within the parton fusion model. Recent results on charm
baryon production in $\Sigma^- A$ interactions at 330 GeV with the WA89
detector disagree with fusion predictions. Intrinsic heavy quark pairs in the
$\Sigma^-(dds)$ wavefunction provide a simple mechanism for producing fast
charm hadrons. We calculate leading charm baryon production from $\Sigma^-$,
$\pi^-$ and $p$ projectiles in a two component model combining parton fusion
with intrinsic charm. Final state $D^{-}$, $\Sigma_{c}^{0}$, $\Xi_{c}^{+}$, and
$\Lambda_{c}^{+}$ $d\sigma/dx_{F}$ distributions and $D^-/D^+$, $D_s^-/D_s^+$
and $\Lambda_c^+/\bar \Lambda^+_c$ asymmetries are compared to WA89 data.
Predictions are made for 650 GeV $\Sigma^- A$ and $\pi^- A$ interactions in the
SELEX detector at Fermilab and for 800 GeV $pA$ interactions.


title:
Energy loss effects on heavy quark production in heavy-ion collisions at
  $\sqrt{s} = 5.5$ $A$TeV

abstract:
  We study the effect of energy loss on charm and bottom quarks in high-energy
heavy-ion collisions including hadronization, longitudinal expansion and
partial thermalization. We consider in detail the detector geometry and single
lepton energy cuts of the ALICE and CMS detectors at the Large Hadron Collider
(LHC) to show the large suppression of high $p_T$ heavy quarks and the
consequences of their semileptonic decays.


title: Factorization and Effective Action for High-Energy Scattering in QCD

abstract:
  I demonstrate that the amplitude of the high-energy scattering can be
factorized in a convolution of the contributions due to fast and slow fields.
The fast and slow fields interact by means of Wilson-line operators -- infinite
gauge factors ordered along the straight line. The resulting factorization
formula gives a starting point for a new approach to the effective action for
high-energy scattering.


title: Instantons and the QCD Vacuum Wavefunctional

abstract:
  We analyze the instanton transitions in the framework of the gauge invariant
variational calculation in the pure Yang-Mills theory. Instantons are
identified with the saddle points in the integration over the gauge group which
projects the Gaussian wave functional onto the gauge invariant physical Hilbert
space. We show that the dynamical mass present in the best variational state
provides an infrared cutoff for the instanton sizes. The instantons of the size
$\rho<1/M$ are suppressed and the large size instanton problem arising in the
standard WKB calculation is completely avoided in the present variational
framework.


title: Decay Rate Asymmetry of Top Squark

abstract:
  We discuss a decay rate asymmetry of the top squark, which is induced by a
new source of CP violation intrinsic in the supersymmetric standard model.
Although new sources of CP violation in this model are severely constrained
from the electric dipole moment of the neutron, an unsuppressed CP-violating
phase can still coexist with a top squark whose mass is accessible by
near-future colliders. Then the dominant decay mode of the top squark has a
width different from its CP conjugate process. The magnitude of this $CP$
asymmetry becomes of order $10^{-3}$.


title:
Matching of U_L(3) x U_R(3) and SU_L(3) x SU_R(3) Chiral Perturbation
  Theories

abstract:
  The heavy singlet field is integrated out from the U_L(3) x U_R(3) Chiral
Perturbation Theory and it is shown how its effects on the low-energy dynamics
are reduced to effective vertices for the light mesons. The results are matched
against the standard SU_L(3) x SU_R(3) Chiral Perturbation Theory in order to
establish the relations between the coupling constants from both theories to
one-loop level accuracy.


title: Charged Lepton G-2 and Constraints on New Physics

abstract:
  A review of the theoretical and experimental values for the charged lepton
(electron and muon) anomalous magnetic moment $a_l= (g_l-2)/2$ is presented.
Employing the most accurate value for the fine structure constant $\alpha^{-1}=
137.03599993(52) (0.0038 ppm)$ obtained \cite {Kin196} from the electron
$(g-2)$ we find the new complete standard model prediction for the anomalous
magnetic moment of the muon $a^{th}_{\mu}= 116591595(67)\times 10^{-11}$. The
comparison of this theoretical value and the precise experimental result \cite
{Sch} yields the estimation for the difference $\Delta a_{\mu}= a^{exp}_{\mu}-
a^{th}_{\mu}$ at the 95% confidence level: $-95 \times 10^{-10} \leq \Delta
a_{\mu}\leq 236 \times 10^{-10}$. The implication of the expected a factor of
about 20 increase of accuracy in the forthcoming Brookhaven National Laboratory
measurement of $a_{\mu}$ implies $-47 \times 10^{-11} \leq \Delta a_{\mu}\leq
118 \times 10^{-11}$, ($95 % C.L.$). This interval is used to get constraints
on the "new physics". The value of the one-loop contributions $a^{B_i}_l$ of
different bosons predicted within extension of the standard model and coupled
to a charged lepton are discussed. The dependence of $a^{B_i}_l$ on the masses
of the bosons and leptons of the vacuum polarization loops are investigated.
The constraints on "new physics" by requiring that the new contributions
$a^{B_i}_{\mu}$ to the muon anomalous magnetic moment lie within the latter
interval $\Delta a_{\mu}$ are obtained.


title: Comment on "Regge Trajectories for All Flavors"

abstract:
  We show that Regge trajectories for all flavors suggested recently by
Filipponi et al. cannot combine both meson spectroscopy and additivity of
intercepts. Other defects of these trajectories are also discussed.


title: New Mass and Mass-Mixing Angle Relations for Pseudoscalar Mesons

abstract:
  We study the origins of the inaccuracies of Schwinger's nonet mass, and the
Sakurai mass-mixing angle, formulae for the pseudoscalar meson nonet, and
suggest new versions of them, modified by the inclusion of the pseudoscalar
decay constants. We use these new formulae to determine the pseudoscalar decay
constants and mixing angle. The results obtained, $f_8/f_\pi = 1.185\pm 0.040,$
$f_9/f_\pi =1.095\pm 0.020,$ $f_\eta /f_\pi = 1.085\pm 0.025,$ $f_{\eta
^{'}}/f_\pi =1.195\pm 0.035,$ $\theta = (-21.4\pm 1.0)^o,$ are in excellent
agreement with experiment.


title:
Current-carrying string loop motion: Limits on the classical description
  and shocks

abstract:
  The dynamical evolution of superconducting cosmic strings is much more
complicated than that of simple Goto-Nambu strings. For this reason, there are
only a few known analytical solutions and no numerical ones. The goal of this
paper is to present numerical solutions for the dynamics of planar
superconducting cosmic string loops. In most cases, a purely dynamical approach
turns out to be insufficient to describe correctly the evolution of a loop due
mainly to the appearance of shocks when spacelike currents are present and
kinks for timelike currents, leading to yet unaccounted for quantum effects.
The consequences of the quantum effects are mostly unknown at this time because
the problem requires a dynamical field theory treatment. It is however likely
that ultimately the result will be massive radiation in the form of charge
carriers from the string.


title: Three jet cross sections in photoproduction at HERA

abstract:
  We calculate three jet cross sections in photoproduction using exact matrix
elements for the direct and resolved contributions. Numerical distributions are
presented in a generic, irreducible set of variables that allows to disentangle
the dynamics of partonic QCD subprocesses from each other and from pure phase
space distributions. The results are compared to preliminary data from the ZEUS
collaboration at HERA. It is found that the largest contribution comes from
photon-gluon fusion in the mass range 36 GeV $< M_{\rm 3-jet} <$ 80 GeV. The
measured leading jet scattering angle distribution is consistent with the
$t$-channel exchange of a massless fermion in $2\to 2$ scattering, where the
third parton is assumed to arise from soft bremsstrahlung. The data are
inconsistent with pure phase space and Rutherford scattering distributions.


title: Super-Kamiokande Constraints on R-parity Violating Supersymmetry

abstract:
  We consider the neutrino oscillations within the minimal supersymmetric
standard model with R-parity violation. The Super-Kamiokande atmospheric
neutrino data are used to set limits on the bilinear R-parity violating terms.
These very stringent limits are out of reach of the other experiments at
present and in the near future.


title: Interpretation of Experimental J^PC Exotic Signals

abstract:
  We investigate theoretical interpretations of the 1.4 GeV J^PC exotic
resonance reported by the E852 collaboration. It is argued that interpretation
in terms of a hybrid meson is untenable. A K-matrix analysis shows that the 1.4
GeV enhancement in the E852 eta pi data can be understood as an interference of
a non-resonant Deck-type background and a resonance at 1.6 GeV. A final state
rescattering calculation shows that the 1.6 GeV hybrid has a eta pi width which
is bounded above by 57 \pm 14 MeV.


title: Heavy flavor decays and OPE in two-dimensional 't Hooft model

abstract:
  The 't Hooft model (two-dimensional QCD in the limit of large number of
colors) is used as a testground for calculations of nonleptonic and
semileptonic inclusive widths of heavy flavors based on the operator product
expansion (OPE). The OPE-based predictions up to terms ${\cal O}(1/m_Q^4)$,
inclusively, are confronted with the "phenomenological" results, obtained by
summation of all open exclusive decay channels, one by one, a perfect match is
found. The issue of duality violations is discussed, the amplitude of
oscillating terms is estimated. The method is applied to the realistic case of
hadronic $\tau$ decays.


title:
Phenomenological Impacts of the CP-odd Rephase-Invariant Phase of the
  Chargino Mass Matrix in the Production of Light Chargino-Pair in $e^+e^-$
  Collisions

abstract:
  One CP--odd rephase-invariant phase appears in the chargino mass matrix in
the minimal Supersymmetric Standard Model. We investigate in detail the
phenomenological impacts of the CP-odd complex phase in the production of light
charginos in $e^+e^-$ annihilation. The values of the chargino masses and the
mixing angles, determining the size of the wino and higgsino components in the
chargino wave functions, are so sensitive to the CP-odd phase that the
constraints on the supersymmetric parameters based on the conventional
assumptions for the parameters are recommended to be re-evaluated including the
CP-odd phase.


title: $4\pi$ Decay Modes of the $f_0(1500)$ Resonance

abstract:
  We investigate the two-body decay modes $\rho\rho, \pi\pi^{\ast}(1300)$ and
$\sigma \sigma$ of the $f_0(1500)$, all leading to the $4\pi$ decay channel, in
a three-state mixing scheme, where the $f_0(1500)$ is a mixture of the
lowest-lying scalar glueball with the nearby isoscalar states of the $0^{++}
Q\bar{Q}$ nonet. In the leading order of this scheme, the decay mechanism of
the $f_0(1500)$ proceeds dominantly via its quarkonia components, which can be
described in the framework of the $^3P_0$ $Q\bar Q$ pair creation model. We
predict the hierarchy of decay branching ratios B with $B(\rho \rho)
^{>}_{\sim} B(\pi\pi) ^{>}_{\sim} B(\sigma \sigma) > B(\pi\pi^{\ast})$,
providing a key signature for the proposed mixing scheme in this leading order
approach.


title: Handbook of Higher Twist Distribution Amplitudes of Vector Mesons in QCD

abstract:
  We give a summary of existing results on higher twist distribution amplitudes
of vector mesons in QCD. Special attention is payed to meson mass corrections
which turn out to be large. A ``shopping list'' is presented of most important
nonperturbative parameters which enter distribution amplitudes.


title:
The Gerasimov-Drell-Hearn sum rule and the single-pion photoproduction
  multipole E0+ close to threshold

abstract:
  The long-standing discrepancy between the Gerasimov-Drell-Hearn sum rule and
the analysis of pion photoproduction multipoles is greatly diminished by use of
s-wave multipoles that are in accord with the predictions of chiral
perturbation theory and describe the experimental data in the threshold region.
The remaining difference may be due to contributions of channels with more
pions and/or heavier mesons whose contributions to the sum rule remain to be
investigated by a direct measurement of the photoabsorption cross sections.


title: Twist Four Longitudinal Structure Function in Light-Front QCD

abstract:
  To resolve various outstanding issues associated with the twist four
longitudinal structure function ${F_L^{\tau=4}(x)}$ we perform an analysis
based on the BJL expansion for the forward virtual photon-hadron Compton
scattering amplitude and equal (light-front) time current algebra. Using the
Fock space expansion for states and operators, we evaluate the twist four
longitudinal structure function for dressed quark and gluon targets in
perturbation theory. With the help of a new sum rule which we have derived
recently we show that the quadratic and logarithmic divergences generated in
the bare theory are related to corresponding mass shifts in old-fashioned
light-front perturbation theory. We present numerical results for the $F_2$ and
$F_L$ structure functions for the meson in two-dimensional QCD in the one pair
approximation. We discuss the relevance of our results for the problem of the
partitioning of hadron mass in QCD.


title: Gauge mediated supersymmetry breaking and neutrino anomalies

abstract:
  Supersymmetric standard model with softly broken lepton symmetry provides a
suitable framework to accommodate the solar and atmospheric neutrino anomalies.
This model contains a natural explanation for large mixing and hierarchal
masses without fine tuning of the parameters. Neutrino spectrum is particularly
constrained in the minimal messenger model (MMM) of gauge mediated SUSY
breaking, since all SUSY breaking effects are controlled in MMM by a single
parameter. We study the structure of neutrino masses and mixing both in MMM and
in simple extensions of it in the context of solar and atmospheric neutrino
anomalies.


title: Some Remarks on the Pomeron and the Odderon in Theory and Experiment

abstract:
  On March 19-21, 1998, a workshop devoted to questions of the pomeron and the
odderon in high energy scattering was held in Heidelberg. This note gives a
personal account of some of the issues discussed at this workshop. Of course,
misconceptions and misunderstandings are to be blamed on us, not on the other
participants of the workshop. A puzzle of odderon physics is identified and a
convenient reaction for its experimental study is discussed.


title: The quantum roll in d-dimensions and the large-d expansion

abstract:
  We investigate the quantum roll for a particle in a $d$-dimensional ``Mexican
hat'' potential in quantum mechanics, comparing numerical simulations in
$d$-dimensions with the results of a large-$d$ expansion, up to order $1/d$, of
the coupled closed time path (CTP) Green's function equations, as well as to a
post-Gaussian variational approximation in $d$-dimensions. The quantum roll
problem for a set of $N$ coupled oscillators is equivalent to a
$(d=N)$-dimensional spherically symmetric quantum mechanics problem. For this
problem the large-N expansion is equivalent to an expansion in $1/d$ where $d$
is the number of dimensions. We use the Schwinger-Mahanthappa-Keldysh CTP
formalism to determine the causal update equations to order $1/d$. We also
study the quantum fluctuations $<r^2>$ as a function of time and find that the
$1/d$ corrections improve the agreement with numerical simulations at short
times (over one or two oscillations) but beyond two oscillations, the
approximation fails to correspond to a positive probability function. Using
numerical methods, we also study how the long time behavior of the motion
changes from its asymptotic ($d \to \infty$) harmonic behavior as we reduce
$d$.


title: The LPM Effect: Comparing SLAC E-146 Data with Experiment

abstract:
  The suppression of photon bremsstrahlung due to a variety of in-medium
effects is discussed. Different electrodynamic suppression effects are
discussed, and compared with the related color analogs. Higher order effects
are considered, and found to be important. Data from SLAC E-146 is discussed,
and compared with theory. The effect of finite thickness targets is emphasized,
since nuclear size is such an important limiting factor for the chromodynamics
effects.


title: Sterile Neutrinos: Phenomenology and Theory

abstract:
  A sterile neutrino in addition to the three known neutrinos seems unavoidable
if one wants a simultaneous understanding of the results of the LSND experiment
indicating $\nu_{\mu}-\nu_e$ oscillation together with other evidences for
neutrino oscillations such as those from solar and atmospheric neutrino
deficits. A major theoretical challenge then is to understand why the sterile
neutrino is so light. A simple solution appears to be to assume that it is the
lightest neutrino of a mirror sector of the universe which has identical matter
and gauge content as the standard model. After a brief review of the
phenomenology, a recently constructed realistic grand unified model based on
the gauge group $SO(10)\times SO(10)^\prime$ that embeds the mirror universe
idea is presented. Detailed predictions for known and the sterile neutrino
sector are given and their consequences for cosmology are mentioned.


title: Solving the rho - pi puzzle by higher charmonium Fock states

abstract:
  A new explanation for the longstanding puzzle of the tiny branching fraction
of psi' --> rho pi relative to that for J/psi --> rho pi was proposed. In the
case of J/psi, we argue that this decay is dominated by a higher Fock state in
which the c cbar pair is in a color-octet ^3S_1 state and annihilates via the
process c cbar --> q qbar. In the case of the psi', we argue that the
probability for the c cbar c pair in this higher Fock state to be close enough
to annihilate is suppressed by a dynamical effect related to the small energy
gap between the mass of the psi' and the D Dbar threshold.


title: Probing the CKM Angle $\gamma$ with $B\to\pi K$ Decays

abstract:
  The decays $B^\pm\to \pi^\pm K$ and $B_d\to \pi^\mp K^\pm$ were observed by
the CLEO collaboration last year; they may play an important role to probe the
angle $\gamma$ of the unitarity triangle of the CKM matrix. After a general
parametrization of their decay amplitudes within the Standard Model, strategies
to constrain and determine the CKM angle $\gamma$ with the help of the
corresponding CP-conserving and CP-violating observables are briefly reviewed.
The theoretical accuracy of these methods is limited by certain rescattering
and electroweak penguin effects. It is emphasized that the rescattering
processes can be included in the bounds on $\gamma$ by using additional
experimental information on $B^\pm\to K^\pm K$ decays, and steps towards the
control of electroweak penguins are pointed out.


title: High energy hadrons in EAS at mountain altitude

abstract:
  An extensive simulation has been carried out to estimate the physical
interpretation of dynamical factors such as <Rh>, <Eh x Rh> in terms of high
energy interaction features, concentrated in the present analysis on the
average transverse momentum. It appears that the large enhancement observed for
<Eh x Rh> versus primary energy, suggesting in earliest analysis a significant
rise of <pt> with energy, is only the result of the limited resolution of the
detectors and remains in agreement with a wide range of models used in
simulations.


title:
A new ordering principle for the classical statistical analysis of
  Poisson processes with background

abstract:
  Inspired by the recent proposal by Feldman and Cousins of a ``unified
approach to the classical statistical analysis of small signals'' based on a
choice of ordering in Neyman's construction of classical confidence intervals,
I propose a new ordering principle for the classical statistical analysis of
Poisson processes with background which minimizes the effect on the resulting
confidence intervals of the observation of less background events than
expected. The new ordering principle is applied to the calculation of the
confidence region implied by the recent null result of the KARMEN neutrino
oscillation experiment.


title:
Unified Explanation of Quark and Lepton Masses and Mixings in the
  Supersymmetric SO(10) Model

abstract:
  We discussed neutrino masses and mixings in SUSY SO(10) model where quarks
and leptons have Yukawa couplings to at least two 10 and one $\bar{126}$ Higgs
scalars. In this model, the Dirac and the right-handed Majorana mass terms are
expressed by linear combinations of quark and charged lepton mass matrices,
which then determine the neutrino mass matrix by the see-saw mechanism. We show
that there are various solutions to reproduce a large mixing angle for
$\nu_\mu-\nu_\tau$ and a small mixing angle for $\nu_e-\nu_\mu$, as well as the
hierarchical mass spectrum of neutrinos.


title:
Analytic two-loop results for selfenergy- and vertex-type diagrams with
  one non-zero mass

abstract:
  For a large class of two-loop selfenergy- and vertex-type diagrams with only
one non-zero mass ($M$) and the vertices also with only one non-zero external
momentum squared ($q^2$) the first few expansion coefficients are calculated by
the large mass expansion. This allows to `guess' the general structure of these
coefficients and to verify them in terms of certain classes of `basis
elements', which are essentially harmonic sums. Since for this case with only
one non-zero mass the large mass expansion and the Taylor series in terms of
$q^2$ are identical, this approach yields analytic expressions of the Taylor
coefficients, from which the diagram can be easily evaluated numerically in a
large domain of the complex $q^2-$plane by well known methods. It is also
possible to sum the Taylor series and present the results in terms of
polylogarithms.


title: Applications of the Large Mass Expansion

abstract:
  The method of the large mass expansion (LME) is investigated for selfenergy
and vertex functions in two-loop order. It has the technical advantage that in
many cases the expansion coefficients can be expressed analytically. As long as
only one non-zero external momentum squared, $q^2$, is involved also the Taylor
expansion (TE) w.r.t. small $q^2$ yields high precision results in a domain
sufficient for most applications. In the case of only one non-zero mass $M$ and
only one external momentum squared, the expansion w.r.t. $q^2/M^2$ is identical
for the TE and the LME. In this case the combined techniques yield analytic
expressions for many diagrams, which are quite easy to handle numerically.


title: Anomalous U(1), gaugino condensation and supergravity

abstract:
  The interplay between gaugino condensation and an anomalous Fayet-Iliopoulos
term in string theories is not trivial and has important consequences
concerning the size and type of the soft SUSY breaking terms. In this paper we
examine this issue, generalizing previous work to the supergravity context.
This allows, in particular, to properly implement the cancellation of the
cosmological constant, which is crucial for a correct treatment of the soft
breaking terms. We obtain that the D-term contribution to the soft masses is
expected to be larger than the F-term one. Moreover gaugino masses must be much
smaller than scalar masses. We illustrate these results with explicit examples.
All this has relevant phenomenological consequences, amending previous results
in the literature.


title: Superstrings and dark matter

abstract:
  We point out that the spectrum and interactions of light states of the
heterotic string indicate a string scale close to the GUT scale, and a mass
generating scale for the gravitationally interacting states around 10^9 GeV if
these states contribute a large fraction to dark matter.


title:
The transitions gamma gamma -> nu bar nu and gamma -> gamma gamma in a
  strong magnetic field

abstract:
  The photon-neutrino process gamma gamma -> nu bar nu and photon splitting are
considered in a strong magnetic field. The partial polarization amplitudes are
calculated within the standard model in the limit of a strong field. The
amplitudes do not depend on the field strength in this limit. Using the vector
parts of the amplitudes, the process of the photon splitting gamma -> gamma
gamma is investigated both below and above the pair creation threshold. The
splitting probabilities are calculated taking account of the photon dispersion
and large radiative corrections near the resonance.


title: The Gluon Propagator in Analytic Perturbation Theory

abstract:
  The structure of the beta function of massless QCD is considered in analytic
perturbation theory (APT). The two-loop analytic effective coupling is written
in terms of the Lambert W function. The method of APT is applied to the gluon
propagator in the Landau gauge. It is shown that there is an nonperturbative
ambiguity in determination of the anomalous dimension function of the gluon
field. One possible resolution of the ambiguity is presented.


title: Scheme Dependence in Polarized Deep Inelastic Scattering

abstract:
  We study the effect of scheme dependence upon the NLO QCD analysis of the
world data on polarized DIS. The reliability of an analysis at NLO is
demonstrated by the consistency of our polarized densities with the NLO
transformation rules relating them to each other. We stress the importance of
the chiral JET scheme in which all the hard effects are consistently absorbed
in the Wilson coefficient functions.


title: Superheavy Dark Matter and Parametric Resonance

abstract:
  We propose a new scenario to produce the superheavy dark matter based on the
inflationary universe. In our scenario, the inflaton couples to both a boson
and a stable fermion. Although the fermion is produced by the inflaton decay
after inflation, almost energy density of the inflaton is transmitted into the
radiation by parametric resonance which causes the explosively copious
production of the boson. We show that the fermion produced by the inflaton
decay can be the superheavy dark matter, whose abundance in the present
universe coincides with the critical density. We also present two explicit
models as examples in which our scenario can be realized. One is the softly
broken supersymmetric theory. The other is the ``singlet majoron model'' with
an assumed neutrino mass matrix. The latter example can simultaneously explain
the neutrino oscillation data and the observed baryon asymmetry in the present
universe through the leptogenesis scenario.


title: The shock waves in relativistic superfluid

abstract:
  We consider the discontinuities in a two-constituent relativistic superfluid.
In the acoustic limit they degenerate into the first and second sound which are
independent up to the second-order linear approximation. Inclusion of the
quadratic deviations relates to the small-amplitude shock. Particularly we
consider a plane shock at low temperature when the phonon excitations
contribute to the normal constituent. So we found the generalization of the
temperature increment and acoustic wave velocity in relativistic superfluid.
The fourth sound speed is also calculated.


title:
Neutrino Textures in the Light of Super-Kamiokande Data and a Realistic
  String Model

abstract:
  Motivated by the Super-Kamiokande atmospheric neutrino data, we discuss
possible textures for Majorana and Dirac neutrino masses within the see-saw
framework. The main purposes of this paper are twofold: first to obtain
intuition from a purely phenomenological analysis, and secondly to explore to
what extent it may be realized in a specific model. We comment initially on the
simplified two-generation case, emphasizing that large mixing is not
incompatible with a large hierarchy of mass eigenvalues. We also emphasize that
renormalization-group effects may amplify neutrino mixing, presenting
semi-analytic expressions for estimating this amplification. Several examples
are then given of three-family neutrino mass textures which may also
accommodate the persistent solar neutrino deficit, with different assumptions
for the neutrino Dirac mass matrices. We comment on a few features of neutrino
mass textures arising in models with a U(1) flavour symmetry. Finally, we
discuss the possible pattern of neutrino masses in a `realistic' flipped SU(5)
model derived from string theory, illustrating how a desirable pattern of
mixing may emerge. Both small- or large-angle MSW solutions are possible,
whilst a hierarchy of neutrino masses appears more natural than
near-degeneracy. This model contains some unanticipated features that may also
be relevant in other models: the neutrino Dirac matrices may not be related
closely to the quark mass matrices, and the heavy Majorana states may include
extra gauge-singlet fields.


title:
CP Violation in the Width Difference of the Scalar Electron Decay due to
  Complex Gaugino Masses

abstract:
  We calculate the width difference of the scalar electron decay,
$\Gamma(\tilde e_L \to e_L\omega) - \Gamma({\bar{\tilde e}}_L \to \bar
e_L\omega)$ in the softly broken supersymmetrized standard model. The CP
asymmetry is assumed to arise from the complex gaugino masses. Even in limit
that the electron mass $m_e$ is vanishing, the difference can be of the order
of $\alpha$.


title:
Electromagnetic properties of hadrons via the $u-d$ mass difference and
  direct photon exchange

abstract:
  We demonstrate that a $u-d$ mass difference (which we estimate to be about 4
MeV) within quantum loops, can reproduce the effects of the Coleman-Glashow
electromagnetic tadpole operator.


title: The Singular Seesaw Mechanism with Hierarchical Dirac Neutrino Mass

abstract:
  The singular seesaw mechanism can naturally explain the atmospheric neutrino
deficit by the maximal oscillation between $\nu_{\mu_L}$ and $\nu_{\mu_R}$.
This mechanism can also induce three different scales of neutrino mass squared
differences, which can explain the neutrino deficits of three independent
experiments (solar, atmospheric, and LSND) by neutrino oscillations. In this
paper we show that the realistic mixing angles among neutrinos can be obtained
by introducing the hierarchy in the Dirac neutrino mass. In the case where
Majorana neutrino mass matrix has rank 2, the solar neutrino deficit is
explained by the vacuum oscillation between $\nu_e$ and $\nu_\tau$. We also
consider the case where Majorana neutrino mass matrix has rank 1. In this case,
the mater enhanced Mikheyev-Smirnov-Wolfenstein solar neutrino solution is
prefered as the solution of the solar neutrino deficit.


title:
Effect of an RRRR dimension 5 operator on the proton decay in the
  minimal SU(5) SUGRA GUT model

abstract:
  We reanalyze the proton decay in the minimal SU(5) SUGRA GUT model. Unlike
previous analyses, we take into account a Higgsino dressing diagram of
dimension 5 operator with right-handed matter fields ($RRRR$ operator). It is
shown that this diagram gives a dominant contribution for $p\to
K^+\bar{\nu}_\tau$ over that from $LLLL$ operator, and decay rate of this mode
can be comparable with that of $p\to K^+\bar{\nu}_\mu$ which is dominated by
the $LLLL$ contribution. It is found that we cannot reduce both the decay rate
of $p\to K^+\bar{\nu}_\tau$ and that of $p\to K^+\bar{\nu}_\mu$ simultaneously
by adjusting relative phases between Yukawa couplings at colored Higgs
interactions. Constraints on the colored Higgs mass $M_C$ and a typical squark
and slepton mass $m_{\tilde{f}}$ from Super-Kamiokande limit become
considerably stronger due to the Higgsino dressing diagram of the $RRRR$
operator: $M_C > 6.5 \times 10^{16}\gev$ for $m_{\tilde{f}} < 1 \tev$, and
$m_{\tilde{f}} > 2.5 \tev$ for $M_C < 2.5 \times 10^{16} \gev$.


title:
Limits on Exotic Quarks in the SU(3)xU(1) Extension of the Standard
  Model from SUSY Search Data

abstract:
  We study the $p\bar p$ production and decay of exotic quarks that are
predicted by the SU(3)$\times$U(1) extension of the Standard Model. We show
that recent experimental searches for SUSY particles at the Tevatron limit the
mass of these quarks to be above 250 GeV. Run II will extend the reach to 320
GeV. This is one example of SUSY search signatures that apply directly to
another, quite different, new physics model.


title: The effect of screening on the $x$ and $Q^2$ bhaviour of $F_2$ slopes

abstract:
  A systematic study of $\frac{\partial F_2(x,Q^2)}{\partial \ln Q^2}$ and
$\frac{\partial \ln F_2(x,Q^2)}{\partial \ln (1/x)}$ is carried out in pQCD
taking screening corrections into account. The result of calculations, which
are different from the non screened DGLAP prediction, are compared and shown to
agree with the available experimental data as well as a pseudo data base
generated from the ALLM'97 parameterization. This pseudo data base allows us to
study in detail our predictions over a wider kinematic region than is available
experimentally, and allows us to make suggestions for future experiments. Our
results are compared with the GRV'94 parameterization (which is used as an
input for our calculations) as well as the recently proposed MRST structure
functions.


title: Search for 1/p^2 Corrections to the Running QCD Coupling

abstract:
  We investigate the occurrence of power terms in the running QCD coupling by
analysing non-perturbative measurements of alpha_s (p) at low momenta obtained
from the lattice three-gluon vertex. Our exploratory study provides some
evidence for power contributions to alpha_s (p) proportional to 1/p^2. Possible
implications for physical observables are discussed.


title: Probing the SUSY breaking scale at an $e^-e^-$ collider

abstract:
  If supersymmetry is spontaneously at a low energy scale then the resulting
gravitino would be very light. The interaction strength of the longitudinal
components of such a light gravitino to electron-selectron pair then becomes
comparable to that of electroweak interactions. Such a light gravitino could
modify the cross-section for $e^_L e^_R-->\tilde {e}_L\tilde {e}_R$ from its
MSSM value. Precision measurement of this cross-section could therefore be used
to probe the low energy SUSY breaking scale.


title: Can thermal inflation solve the monopole problem ?

abstract:
  It is shown that thermal inflation arises naturally in rank greater than five
unified theories when non-renormalisable terms are introduced. Thermal
inflation is driven by two Higgs fields \Phi_{B-L} and \bar{\Phi}_{B-L} which
also break U(1)_{B-L} when acquiring vevs at the end of inflation. The
inflationary period provides enough e-foldings to solve the monopole problem
for M_{B-L} \geq 10^{12} GeV. We point out that observations suggest that
M_{B-L} \simeq 10^{14} GeV.


title: Gravitationally violated U(1) symmetry and neutrino anomalies

abstract:
  The current searches for neutrino oscillations seem to suggest an approximate
$L_e-L_\m-L_{\tau}$ flavor symmetry. This symmetry implies a pair of degenerate
neutrinos with mass $m_0$ and large leptonic mixing. We explore the possibility
that gravitational interactions break this global symmetry. The Planck scale
suppressed breaking of the $L_e-L_\m-L_{\tau}$ symmetry is shown to lead to the
right amount of splitting among the degenerate neutrinos needed in order to
solve the solar neutrino problem. The common mass $m_0$ of the pair can be
identified with the atmospheric neutrino scale. A concrete model is proposed in
which smallness of $m_0$ and hierarchy in the solar and atmospheric neutrino
scales get linked to hierarchies in the weak, grand unification and the Planck
scales.


title:
Next-to-leading order jet cross sections in polarized hadronic
  collisions

abstract:
  We present a next-to-leading order computation in QCD of one-jet and two-jet
cross sections in polarized hadronic collisions. Our results are obtained in
the framework of a general formalism that deals with soft and collinear
singularities using the subtraction method. We construct a Monte Carlo program
that generates events at the partonic level. We use this code to give
phenomenological predictions for $pp$ collisions at $\sqrt{S}=500$ GeV,
relevant for the spin physics program at RHIC. The possibility of using jet
data to constrain the poorly known polarized parton densities is examined.


title: The Region of Validity of Homogeneous Nucleation Theory

abstract:
  We examine the region of validity of Langer's picture of homogeneous
nucleation. Our approach is based on a coarse-grained free energy that
incorporates the effect of fluctuations with momenta above a scale k. The
nucleation rate I = A_k exp(-S_k) is exponentially suppressed by the action S_k
of the saddle-point configuration that dominates tunnelling. The factor A_k
includes a fluctuation determinant around this saddle point. Both S_k and A_k
depend on the choice of k, but, for 1/k close to the characteristic length
scale of the saddle point, this dependence cancels in the expression for the
nucleation rate. For very weak first-order phase transitions or in the vicinity
of the spinodal decomposition line, the pre-exponential factor A_k compensates
the exponential suppression exp(-S_k). In these regions the standard nucleation
picture breaks down. We give an approximate expression for A_k in terms of the
saddle-point profile, which can be used for quantitative estimates and
practical tests of the validity of homogeneous nucleation theory.


title:
Variational Estimation of the Wave Function at Origin for Heavy
  Quarkonium

abstract:
  The wave function at the origin (WFO) is an important quantity in studying
many physical problems concerning heavy quarkonia. However, when one used the
variational method with fewer parameters, in general, the deviation of
resultant WFO from the "accurate" solution was not well estimated. In this
paper, we discuss this issue by employing several potential forms and trial
wave functions in detail and study the relation between WFO and the reduced
mass.


title:
Correlation between neutrino oscillations and collider signals of
  supersymmetry in an R-parity violating model

abstract:
  Motivated by the recent Super-Kamiokande results on atmospheric neutrinos, we
incorporate massive neutrinos, with large angle oscillation between the second
and third generations, in a scenario with R-parity violating supersymmetry. We
emphasize the testability of such models through the observation of comparable
numbers of muons and taus, produced together with the W-boson, in decays of the
lightest neutralino. A distinctly measurable decay gap is another remarkable
feature of such a scenario.


title:
Pattern of Chiral Symmetry Restoration at Finite Temperature in A
  Supersymmetric Composite Model

abstract:
  The structure of chiral symmetry restorations at finite temperature is
thoroughly investigated in the supersymmetric Nambu-Jona-Lasinio model with a
soft supersymmetry breaking term. It is found that the broken chiral symmetry
at vanishing temperature is restored at sufficiently high temperature in two
patterns, i. e., the first order and second order phase transition depending on
the choice of the coupling constant $G$ and the supersymmetry breaking
parameter $\Delta$. The critical curves expressing the phase boundaries in the
$G-\Delta$ plane are completely determined and the dynamically generated
fermion mass is calculated as a function of temperature.


title: Probing Multiparton Correlations at CEBAF

abstract:
  In this talk, I explore the possibilities of probing the multiparton
correlation functions at CEBAF at its current energy and the energies with its
future upgrades.


title: Non Singlet StructureFunction At Low x

abstract:
  We comment on the uniqueness of t-evolution$(t=log(Q^2/\Lambda^2))$ of
non-singlet structure functions at low x obtained fromDGLAP equations.


title: Textures for Neutrino Mass Matrices in Gauge Theories

abstract:
  We review previous work on neutrino mass textures in gauge theories. Such
textures may arise as a result of flavour symmetries. In a given theory, it is
possible to give a classification of heavy Majorana neutrino mass matrices,
assuming the Dirac masses of the neutrinos to be of the same form as the ones
of the up-quarks. Heavy Majorana neutrino mass matrices leading to large
neutrino mixing, are tabulated as an example. Such solutions are now of
interest, in the light of the Super-Kamiokande data.


title:
Atmospheric neutrinos at Super-Kamiokande and parametric resonance in
  neutrino oscillations

abstract:
  We consider the oscillations of atmospheric neutrinos in the earth in the
three-neutrino scheme with a $\Delta m^2$ hierarchy and a small admixture of
the electron neutrino in the heavy mass eigenstate characterized by the mixing
angle $\theta_{13}$. We show that for $\Delta m^2 \simeq (0.5 - 3) \times
10^{-3}$ eV$^2$ indicated by the Super-Kamiokande data and $\sin^2 2\theta_{13}
\aprle 0.2$, the oscillations of multi-GeV neutrinos in the subdominant
$\nu_{\mu} \leftrightarrow \nu_e$ mode are enhanced by the MSW and parametric
resonances. The parametric resonance, which occurs when the neutrinos cross the
core of the earth, dominates for $\Delta m^2 \simeq (1 - 2)\times 10^{-3}$
eV$^2$, $\sin^2 2\theta_{13} \aprle 0.06$. The resonance matter effects lead to
an observable excess of the e-like events with a specific zenith angle
dependence even for small $\theta_{13}$. The up-down asymmetry of the multi-GeV
e-like events can reach 15% for $|\cos \Theta_e| > 0.2$ and up to 30% for
$|\cos \Theta_e| > 0.6$, where $\Theta_e$ is the zenith angle of the electron.
The resonance matter effects are relevant for the interpretation of the
Super-Kamiokande data.


title: Bose-Einstein correlations in multiple particle production

abstract:
  Bose-Einstein correlations are studied in the framework of a class of
independent particle production models. This generalizes the studies for a
variety of models proposed previously. It is shown that the Bose-Einstein
correlations lead for this class of models to Einstein's condensation at
sufficiently high density. They also enhance unusual charge distributions and
may explain the centauro and anticentauro events reported by cosmic ray
physicists. For typical models the correlations cause a shrinking of the
momentum distribution of the produced identical particles and an apparent
shrinking of the production region.


title: Large Leptonic Flavor Mixing and the Mass Spectrum of Leptons

abstract:
  Implications of a simple model for the mass generation of leptons are
studied, in particular for the upcoming long-baseline neutrino experiments. The
flavor mixing angles are large (nearly maximal). The probability for the
long-baseline \nu_\mu \leftrightarrow \nu_e oscillation is predicted to be
about 1%.


title: Global approximants with renormalization scale invariance in pQCD

abstract:
  Truncated perturbative series (TPS's) of any observable have the unphysical
dependence on the choice of the renormalization scale (RScl). The diagonal
Pad\'e approximants (dPA's) to any TPS of an observable possess the favorable
property of being invariant in the large-${\beta_0}$ limit. This means that
they are invariant under the change of the RScl $\mu^2$ when the ``running''
coupling parameter ${\alpha}_s(\mu^2)$ evolves according to the one-loop
renormalization group equation. We present a method which generalizes this
result -- the resulting new approximants are fully RScl-invariant in the
perturbative QCD (pQCD). Further, we present some numerical examples. Both the
dPA's and the new approximants are global, i.e., their structure goes beyond
the usual (polynomial) TPS form and thus they could reveal some
non-perturbative effects.


title:
Aperiodic Spin-Flavor Conversions and $\tilde{\nu}_e$ from the Sun with
  Random Magnetic Field

abstract:
  The magnetic field in the solar convective zone has a random small-scale
component with the r.m.s. value substantially exceeding the strength of a
regular large-scale field. For two Majorana neutrino flavors $\times$ two
helicities in the presence of a neutrino transition magnetic moment and nonzero
neutrino mixing we analyze the displacement of the allowed ($\Delta m^2 -
\sin^22\theta$) - parameter region reconciled for the SuperKamiokande(SK) and
radiochemical (GALLEX, SAGE, Homestake) experiments in dependence on the r.m.s.
magnetic field value $b$. We find an effective production of electron
antineutrinos in the Sun even for small neutrino mixing through the cascade
conversions in the random magnetic field that would be a signature of the
Majorana nature of neutrino if $\tilde{\nu}_{eR}$ will be registered. Basing on
the present SK bound on electron antineutrinos we also estimated the
corresponding excluded area in the plane $\Delta m^2, \sin^22\theta$.


title: Haggling over the fine-tuning price

abstract:
  We amplify previous discussions of the fine-tuning price to be paid by
supersymmetric models in the light of LEP data, especially the lower bound on
the Higgs boson mass, studying in particular its power of discrimination
between different parameter regions and different theoretical assumptions. The
analysis is performed using the full one-loop effective potential. The whole
range of $\tan\beta$ is discussed, including large values. In the minimal
supergravity model with universal gaugino and scalar masses, a small
fine-tuning price is possible only for intermediate values of $\tan\beta$.
However, the fine-tuning price in this region is significantly higher if we
require $b-\tau$ Yukawa-coupling unification. On the other hand, price
reductions are obtained if some theoretical relation between MSSM parameters is
assumed, in particular between $\mu_0$, $M_{1/2}$ and $A_0$. Significant price
reductions are obtained for large $\tan\beta$ if non-universal soft Higgs mass
parameters are allowed. Nevertheless, in all these cases, the requirement of
small fine tuning remains an important constraint on the superpartner spectrum.
We also study input relations between MSSM parameters suggested in some
interpretations of string theory: the price may depend significantly on these
inputs, potentially providing guidance for building string models. However, in
the available models the fine-tuning price may not be reduced significantly.


title: Superball dark matter

abstract:
  Supersymmetric models predict a natural dark-matter candidate, stable
baryonic Q-balls. They could be copiously produced in the early Universe as a
by-product of the Affleck-Dine baryogenesis. I review the cosmological and
astrophysical implications, methods of detection, and the present limits on
this form of dark matter.


title: Degenerate Dirac Neutrinos

abstract:
  A simple extension of the standard model is proposed in which all the three
generations of neutrinos are Dirac particles and are naturally light. We then
assume that the neutrino mass matrix is diagonal and degenerate, with a few eV
mass to solve the dark matter problem. The self energy radiative corrections,
however, remove this degeneracy and allow mixing of these neutrinos. The
electroweak radiative corrections then predict a lower bound on the $\nu_\mu -
\nu_e$ mass difference which solves the solar neutrino problem through MSW
mechanism and also predict a lower bound on the $\nu_\tau - \nu_\mu$ mass
difference which is just enough to explain the atmospheric neutrino problem as
reported by super Kamiokande.


title:
Top quark decay into charged Higgs boson in a general Two-Higgs-Doublet
  model: implications for the TEVATRON data

abstract:
  We analyze the unconventional top quark decay mode t -> H^+ b at the quantum
level within the context of general Two-Higgs-Doublet models by including the
full electroweak effects from the Yukawa couplings. The results are presented
in the on-shell renormalization scheme with a physically well motivated
definition of tan(beta). While the QCD corrections have been taken into account
in the current experimental analyses of that decay, the electroweak effects
have always been neglected. However, we find that they can be rather large and
could dramatically alter the interpretation of the present data from the
Tevatron collider. For instance, in large portions of the parameter space the
electroweak effects prevent the Tevatron data from placing any bound at all to
the charged Higgs mass for essentially any value of tan(beta).


title: Three Electroweak Results from Lattice QCD

abstract:
  Quantum chromodynamics is needed to understand quarks and, hence, to
determine the quarks' Yukawa couplings from experimental measurements. As a
short illustration, the results of three lattice calculations are given.


title:
On wave function renormalization and related aspects in heavy fermion
  effective field theories

abstract:
  We reconsider the question of wave function renormalization in heavy fermion
effective field theories. In particular, we work out a simple and efficient
scheme to define the wave function renormalization with respect to the lowest
order heavy fermion propagator. The method presented is free of a set of
ambiguities which arise in heavy fermion effective field theories. In this
context, we discuss the approaches used in the literature so far. We also
calculate the fourth order pion mass contribution to the nucleon mass shift and
discuss the tree and loop contributions to the electric Sachs form factor of
the nucleon.


title: Neutrino Propagation in Matter

abstract:
  The enhancement of neutrino oscillations in matter is briefly reviewed. Exact
and approximate solutions of the equations describing neutrino oscillations in
matter are discussed. The role of stochasticity of the media that the neutrinos
propagate through is elucidated.


title: Observables in Unpolarized and Polarized Virtual Compton Scattering

abstract:
  Below pion threshold virtual Compton scattering off the nucleon gives access
to the generalized electromagnetic polarizabilities. Different theoretical
results for the generalized polarizabilities have been compared. In particular,
the influence of the generalized polarizabilities on the unpolarized cross
section and on double polarization observables has been investigated.
Predictions for these observables have been obtained in the linear sigma model
and chiral perturbation theory.


title:
Complete 2-loop Quantum Electrodynamic Contributions to the Muon
  Lifetime in the Fermi Model

abstract:
  The complete 2-loop quantum electrodynamic corrections to the muon lifetime
are calculated in the Fermi theory. The exact result for the effects of virtual
and real photons, virtual electrons, muons as well as e+e- pair creation is
  Delta Gamma_QED
  = Gamma_0(alpha/pi)^2[(156815/5184)-(1036/27)zeta(2)-(895/36)zeta(3)
  +(67/8)zeta(4)+53zeta(2)ln(2)]
  = Gamma_0(alpha/pi)^2(6.743)
  where Gamma_0 is the tree-level width. The theoretical error in the value of
the Fermi coupling constant, G_F, is now rendered negligible compared to the
experimental uncertainty coming from the measurement of the muon lifetime. The
overall error in G_F is then roughly halved giving
  G_F = (1.16637 +/- 0.00001) x 10^(-5) GeV^(-2).


title: Particle Physics Implications of Neutrinoless Double Beta Decay

abstract:
  Neutrinoless double beta decay is a sensitive probe of the patterns of
neutrino masses and mixings if the neutrinos are Majorana particles as well as
other new physics scenarios beyond the standard model. In this talk, the
present experimental lower bound on the lifetime for $\beta\beta_{0\nu}$ is
used to constrain the neutrino mixings and set limits on the parameters of the
new physics scenarios such as the left-right symmetric models, R-parity
violating SUSY models etc which lead to this process. We also discuss proposed
high precision searches for $\beta\beta_{0\nu}$ decay that can provide
extremely valuable insight not only into the nature of neutrino mixings and
masses but also put constraints on (or even rule out) new physics scenarios.


title:
Fermion-Antifermion Condensate Contribution to the Anomalous Magnetic
  Moment of a Fundamental Dirac Fermion

abstract:
  We consider the contribution of fermion-antifermion condensates to the
anomalous magnetic moment of a fermion in a vacuum in which such condensates
exist. The real part of the condensate contribution to the anomalous magnetic
moment is shown to be zero. A nonzero imaginary part is obtained below the
kinematic threshold for intermediate fermion-antifermion pairs. The calculation
is shown to be gauge-parameter independent provided a single fermion mass
characterizes both the fermion propagator and condensate-sensitive
contributions, suggestive of a dynamically-generated fermion mass. The nonzero
imaginary part is then argued to correspond to the kinematic production of the
intermediate-state Goldstone bosons anticipated from a chiral-noninvariant
vacuum. Finally, speculations are presented concerning the applicability of
these results to quark electromagnetic properties.


title: Production of a Higgs pseudoscalar plus two jets in hadronic collisions

abstract:
  We consider the production of a Higgs pseudoscalar accompanied by two jets in
hadronic collisions. We work in the limit that the top quark is much heavier
than the Higgs pseudoscalar and use an effective Lagrangian for the
interactions of gluons with the pseudoscalar. We compute the amplitudes
involving: 1) four gluons and the pseudoscalar, 2) two quarks, two gluons and
the pseudoscalar and 3) four quarks and the pseudoscalar. We find that the
pseudoscalar amplitudes are nearly identical to those for the scalar case, the
only differences being the overall size and the relative signs between terms.
We present numerical cross sections for proton-proton collisions with
center-of-mass energy 14 TeV.


title: Higgs boson interactions in supersymmetric theories with large tan beta

abstract:
  We show that radiative corrections to the Higgs potential in supersymmetric
theories with large tan beta generically lead to large differences in the light
Higgs boson decay branching fractions compared to those of the standard model
Higgs boson. In contrast, the light Higgs boson production rates are largely
unaffected. We identify W h associated production followed by Higgs boson
decays to photons or to leptons via W W* as potential experimental probes of
these theories.


title: Multilepton Signatures for Leptoquarks

abstract:
  The production of third generation leptoquarks can give rise to multilepton
events accompanied by jets and missing transverse energy.
  In this work we study the signals of these leptoquarks at the CERN Large
Hadron Collider and compare them with the ones expected in supersymmetric
models.


title:
The Decays $K \to \pi \ell^+ \ell^-$ beyond Leading Order in the Chiral
  Expansion

abstract:
  We present a model-independent analysis of $K^+\to\pi^+\ell^+\ell^-$ and
$K_S\to\pi^0\ell^+\ell^-$ decays, including $K\to 3 \pi$ unitarity corrections
and a general decomposition of the dispersive amplitude. From the existing data
on $K^+\to\pi^+ e^+ e^-$ we predict the ratio $R=
B(K^+\to\pi^+\mu^+\mu^-)/B(K^+\to\pi^+ e^+ e^-)$ to be larger than 0.23, in
slight disagreement with the recent measurement $R = 0.167 \pm 0.036$.
Consequences for the $K^\pm \to\pi^\pm e^+ e^-$ charge asymmetries and for the
$K_L\to\pi^0 e^+ e^-$ mode are also discussed.


title: Axial Currents of Virtual Charm in Light Quark Processes

abstract:
  The systematic investigations of the role of the virtual charm axial currents
in the decay of $B$-mesons to $\eta '$ $K$ and the spin structure of the
nucleon are performed. We reduce the divergence of the virtual charm axial
current to a specific gluon operator. Since this operator receives the main
contribution from topologically nontrivial components of the QCD vacuum, we
rederive the Dyakonov-Petrov Effective Action, based on the instanton QCD
vacuum model. This action is applied to the calculations of the coupling of
$\eta '$ to the charm axial current and found $f_{\eta '}^{(c)} (\mu \simeq
m_c) = - (12.3 \sim 18.4 {\rm MeV}), $ providing a possibility for the
explanations of the recent experimental data on $B \to \eta ' K$-decay.
Analogous calculations of the virtual charm content of the nucleon spin leads
to $\Delta c (\mu \simeq m_c) = - (0.015 \sim 0.024),$ which is one order of
magnitude smaller than the analogous contribution of the strange quark.


title: Scaling Region Meson Photoproduction and Elastic Form Factors of Hadrons

abstract:
  First, I define generalized Bloom-Gilman duality and Bjorken-like scaling for
inclusive photoproduction of pions, relating Quark-Parton Model description in
the deep-inelastic region to the properties of exclusive resonance excitation.
Secondly, connection between inclusive and exclusive processes is established
in the formalism of Nonforward Parton Densities used here to predict deviations
from dimensional scaling for a variety of observables: nucleon and pion elastic
form factors, and pion Compton scattering.


title: Super-gravity unification with bilinear R-parity violation

abstract:
  Bilinear R-parity violation (BRpV) provides the simplest and most meaningful
way to include such effects into the Minimal Supersymmetrical Standard Model
(MSSM). It is defined by a quadratic superpotential term $\epsilon L H$ which
mixes lepton and Higgs superfields and mimics the effects of models with
spontaneous breaking. I review some of its main features and show how large
$\epsilon$ values can lead to a small neutrino mass radiatively, without any
fine-tuning. I discuss the effect of BRpV on gauge and Yukawa unification,
showing how bottom--tau unification can be achieved at any value of
$\tan\beta$. However, for very large m $\epsilon$ values the large $\tan\beta$
solution is ruled out.


title: Neutrinos on Earth and in the Heavens

abstract:
  Recent data lead us to a simple and intriguing form of the neutrino mass
matrix. In particular, we find solar neutrino oscillations to be nearly maximal
(and rule out the small-angle MSW explanation of solar neutrino observations)
if relic neutrinos comprise at least one~percent of the critical mass density
of the universe.


title:
Direct computation of inelastic photon-neutrino processes in the
  Standard Model

abstract:
  In this paper, we compute the Standard Model polarized amplitudes and cross
sections of the processes $\gamma\nu\to\gamma\gamma \nu$, $\gamma\gamma \to
\gamma\nu\bar\nu$ and $\nu\bar\nu \to \gamma\gamma\gamma$, for centre-of-mass
energies $\omega$ within the range of validity of the Fermi theory. By using a
large electron-mass expansion of the exact result, we also derive the first
correction term to the effective, low-energy ($\omega < m_e$) formula for
$\gamma\nu\to\gamma\gamma \nu$. Finally, we discuss possible astrophysical
implications of our results and provide simple fits to the exact expressions.


title: Energy barrier in the two-Higgs model

abstract:
  The electroweak model is extended by a second Higgs doublet and a numerical
investigation of static, finite energy classical solutions is performed. The
results indicate that for a large domain of the parameters of the Higgs
potential, the energy barrier between topologically distinct vacua of the
Lagrangian is constituted by a bisphaleron.


title:
Bi-Maximal Neutrino Mixing in the MSSM with a Single Right-Handed
  Neutrino

abstract:
  We discuss neutrino masses in the framework of a minimal extension of the
minimal supersymmetric standard model (MSSM) consisting of an additional single
right-handed neutrino superfield $N$ with a heavy Majorana mass $M$, which
induces a single light see-saw mass $m_{\nu_3}$ leaving two neutrinos massless
at tree-level. This trivial extension to the MSSM may account for the
atomospheric neutrino data via $\nu_{\mu}\to \nu_{\tau}$ oscillations by
assuming a near maximal mixing angle $\theta_{23}\sim \pi/4$ and taking $\Delta
m_{23}^2 \sim m_{\nu_3}^2 \sim 2.5\times 10^{-3} eV^2$. In order to account for
the solar neutrino data we appeal to one-loop radiative corrections involving
internal loops of SUSY particles, which we show can naturally generate an
additional light neutrino mass $m_{\nu_{2}}\sim 10^{-5} eV$ again with near
maximal mixing angle $\theta_{12}\sim \pi/4$. The resulting scheme corresponds
to so-called ``bi-maximal'' neutrino mixing involving ``just-so'' solar
oscillations.


title:
Testing for New Physics with Low-Energy Anti-Neutrino Sources: LAMA as a
  Case Study

abstract:
  Some electroweak models with extended neutral currents, such as those based
on the $E_6$ group, lead to an increase of the $\bar{\nu}-e$ scattering cross
section at energies below 100 keV. We propose to search for the heavy Z' boson
contribution in an experiment with a high-activity artificial neutrino source
and with a large-mass detector. We present the case for the LAMA experiment
with a large NaI(Tl) detector located at the Gran Sasso underground laboratory.
The neutrino flux is known to within a one percent accuracy, in contrast to the
reactor case and one can reach lower neutrino energies. Both features make our
proposed experiment more sensitive to extended gauge models, such as the $\chi$
model. For a low enough background the sensitivity to the $Z_\chi$ boson mass
would reach 600 GeV for one year running of the experiment.


title: Hadronization of a Quark-Gluon Plasma in the Chromodielectric Model

abstract:
  We have carried out simulations of the hadronization of a hot, ideal but
effectively massive quark-gluon gas into color neutral clusters in the
framework of the semi-classical SU(3) chromodielectric model. We have studied
the possible quark-gluon compositions of clusters as well as the final mass
distribution and spectra, aiming to obtain an insight into relations between
hadronic spectral properties and the confinement mechanism in this model.


title:
Two-Loop Effective Potential Calculation of the Lightest CP-Even
  Higgs-Boson Mass in the MSSM

abstract:
  We calculate a two-loop effective potential to the order of {\cal
O}(\lambda_t^2\alpha_s) in the MSSM. We then study the corresponding two-loop
corrections to the CP-even Higgs-boson mass for arbitrary \tan\beta and
left-right top-squark mixings. We find that the lightest Higgs-boson mass is
changed by at most a few GeV. We also show the improved scale dependence and
compare to previous two-loop analyses.


title: Fracture Functions for Diffractive and Leading Proton DIS

abstract:
  We present a combined QCD analysis of diffractive and leading proton deep
inelastic scattering data using the framework of fracture functions. It is
shown that this framework allows a precise and unified perturbative QCD
description for the data, alternative to those that relay on Regge
factorization.


title: Gauge Model for Maximal Neutrino Mixing

abstract:
  The recently announced Super-Kamiokande data on atmospheric neutrino
oscillation seems to require a maximal mixing between the $\nu_{\mu}$ and
$\nu_{\tau}$ within the conventional three neutrino picture. It is then
tempting to suggest as has been done in literature, that the solar neutrino
deficit be also understood as resulting from a maximal mixing between $\nu_e$
and $\nu_{\mu}$. In this letter, we propose a left-right symmetric extension of
the standard model where permutation symmetry leads to one of the maximal
mixing patterns in a technically natural manner. The double seesaw mechanism
gives small Majorana masses for neutrinos needed to understand the atmospheric
as well as the solar neutrino puzzles.


title: Axions from wall decay

abstract:
  We discuss the decay of axion walls bounded by strings and present numerical
simulations of the decay process. In these simulations, the decay happens
immediately, in a time scale of order the light travel time, and the average
energy of the radiated axions is $<\omega_a > \simeq 7 m_a$ for $v_a/m_a\simeq
500$. $<\omega_a>$ is found to increase approximately linearly with
$\ln(v_a/m_a)$. Extrapolation of this behaviour yields $<\omega_a> \simeq 60
m_a$ in axion models of interest.


title:
The final-state interaction phases of the two-body B decay: The bounds
  from the updated data

abstract:
  The updated experimental data are used to analyze the final-state interaction
phases of the two-body decay amplitudes of the B mesons. Combining the upper
bounds on the branching fractions of the color-suppressed modes with those of
the charged modes, we have set constraints on the relative phases between the
amplitudes $A(B^0 \to X^- Y^+)$ and $A(B^+ \to X^0 Y^+)$ where $X=\overlien{D}$
or $\overine{D}^*$ and $Y=\pi$ and $\rho$. The numbers that we have obtained
point to small final-state interactions. When these relative phases are
expressed in those of the isospin amplitudes, the bounds become less tight
since experimental errors accumulate. In the decay where many multibody
channels are open, however, there is little advantage in breaking up the
observed amplitudes into the isospin eigenchannels for analysis of the
final-state interactions.


title:
Neutrino Oscillations and Flavor Structure of Supersymmetry without
  R-Parity

abstract:
  Focusing on a simple three neutrino oscillation scenario motivated by the
recent Super-Kamiokande result, we discuss both tree-level and 1-loop
contributions to neutrino masses in supersymmetry without R-parity, aiming at
discerning the flavor structure issues of the theory. The single-VEV
parametrization framework, which allows the first consistent treatment of the
bilinear and trilinear R-parity violating terms, and hence the tree and 1-loop
contributions, without any assumption on the nature of R-parity violation.
Though the very small neutrino masses implies stringent suppressions of the
relevant R-parity violating couplings, we show that there is still room for
understanding the suppressions as a simple consequence of the general flavor
hierarchy.


title: Implications of Color Gauge Symmetry For Nucleon Spin Structure

abstract:
  We study the chromodynamical gauge symmetry in relation to the internal spin
structure of the nucleon. We show that 1) even in the helicity eigenstates the
gauge-dependent spin and orbital angular momentum operators do not have
gauge-independent matrix element; 2) the evolution equations for the gluon spin
take very different forms in the Feynman and axial gauges, but yield the same
leading behavior in the asymptotic limit; 3) the complete evolution of the
gauge-dependent orbital angular momenta appears intractable in the light-cone
gauge. We define a new gluon orbital angular momentum distribution $L_g(x)$
which {\it is} an experimental observable and has a simple scale evolution.
However, its physical interpretation makes sense only in the light-cone gauge
just like the gluon helicity distribution $\Delta g(x)$y.


title: Anomalous Global Strings and Primordial Magnetic Fields

abstract:
  We propose a new mechanism for the generation of primordial magnetic fields,
making use of the magnetic fields which are induced by anomalous global strings
which couple to electromagnetism via Wess-Zumino type interactions. This
mechanism can be realized in QCD by utilizing pion strings, global vortices
which appear in the linear sigma model which describes physics below the QCD
confinement scale. During the chiral symmetry breaking phase transition, pion
strings can be produced, thus leading to primordial magnetic fields. We
calculate the magnitude and coherence length of these fields. They are seen to
depend on the string dynamics. With optimistic assumptions, both the magnitude
and coherence scale of the induced magnetic fields can be large enough to
explain the seed magnetic fields of greater than $10^{-23}$ Gauss necessary to
produce the observed galactic magnetic fields via the galactic dynamo
mechanism.


title:
Are there two sterile neutrinos cooscillating with $\nu_e$ and
  $\nu_\mu$?

abstract:
  The existence of two sterile neutrinos $\nu_s$ and $\nu'_s$ (blind to all
Standard-Model interactions) is shown to be implied by a model of fermion
"texture" that we develop since some time. They may mix nearly maximally with
two of three conventional neutrinos, say $\nu_e$ and $\nu_\mu$, thus leading to
neutrino oscillations, say $\nu_e \to \nu_s$ and $\nu_\mu \to \nu'_s$, with
nearly maximal amplitudes. Then, they can be responsible for the observed
deficits of solar $\nu_e$'s and atmospheric $\nu_\mu$'s, respectiv% ely, but by
themselves do not help to explain the LSND results for $\nu_\mu \to \nu_e$
oscillations. On the other hand, they are consistent with the CHOOZ negative
result. At the moment, the experiment cannot decide, whether the deficit of
atmospheric $\nu_\mu$'s, confirmed by the recent \SK findings, has to be
related to the oscillations $\nu_\mu \to \nu_\tau$ or $\nu_\mu \to \nu'_s$. In
the last Section of the paper, a new notion of "non-Abelian spin-1/2 fermions"
is presented in the context of a composite option for fermion families.


title: Transverse momentum broadening due to the multiple scattering

abstract:
  Using the Drell-Yan process in hadron-nucleus collisions and deeply inelastic
lepton-nucleus scattering (DIS) as examples, I show that the transverse
momentum broadening can be expressed in terms of four-parton correlation
functions. I argue that jet broadening in DIS provide an excellent measurement
of the four-parton correlation functions and a test of QCD treatment of the
multiple scattering.


title:
Radiative Effects in Processes of Diffractive Vector Meson
  Electroproduction

abstract:
  The electromagnetic radiative correction to the cross section of the vector
meson electroproduction is calculated. Explicit covariant formulae for the
observed cross section are obtained. The dependence of the radiative correction
on the experimental resolution and on the inelasticity cut is discussed.
FORTRAN code DIFFRAD based on both exact (ultrarelativistic) and approximate
sets of the formulae for the radiative correction to the cross section is
presented. The detailed numerical analysis for kinematical conditions of the
recent experiments on the diffractive electroproduction of vector mesons is
given.


title: Pair Production in the Collapse of a Hopf Texture

abstract:
  We consider the collapse of a global "Hopf" texture and examine the
conjecture, disputed in the literature, that monopole-antimonopole pairs can be
formed in the process. We show that such monopole-antimonopole pairs can indeed
be nucleated in the course of texture collapse given appropriate initial
conditions. The subsequent dynamics include the recombination and annihilation
of the pair in a burst of outgoing scalar radiation.


title:
The P_33(1232) resonance contribution into the amplitudes
  M_{1+}^{3/2},E_{1+}^{3/2},S_{1+}^{3/2} from an analysis of the p(e,e'p)\pi^0
  data at Q^2 = 2.8, 3.2, and 4 (GeV/c)^2 within dispersion relation approach

abstract:
  Within the fixed-t dispersion relation approach we have analysed the TJNAF
and DESY data on the exclusive p(e,e'p)\pi^0 reaction in order to find the
P_{33}(1232) resonance contribution into the multipole amplitudes
M_{1+}^{3/2},E_{1+}^{3/2},S_{1+}^{3/2}. As an input for the resonance and
nonresonance contributions into these amplitudes the earlier obtained solutions
of the integral equations which follow from dispersion relations are used. The
obtained values of the ratio E2/M1 for the \gamma^* N \to P_{33}(1232)
transition are: 0.039\pm 0.029, 0.121\pm 0.032, 0.04\pm 0.031 for Q^2= 2.8,
3.2, and 4 (GeV/c)^2, respectively. The comparison with the data at low Q^2
shows that there is no evidence for the presence of the visible pQCD
contribution into the transition \gamma N \to P_{33}(1232) at Q^2=3-4 GeV^2.
The ratio S_{1+}^{3/2}/M_{1+}^{3/2} for the resonance parts of multipoles is:
-0.049\pm 0.029, -0.099\pm 0.041, -0.085\pm 0.021 for Q^2= 2.8, 3.2, and 4
(GeV/c)^2, respectively. Our results for the transverse form factor G_T(Q^2) of
the \gamma^* N \to P_{33}(1232) transition are lower than the values obtained
from the inclusive data. With increasing Q^2, Q^4G_T(Q^2) decreases, so there
is no evidence for the presence of the pQCD contribution here too.


title: MSSM Higgs Boson Phenomenology at the Tevatron Collider

abstract:
  The Higgs sector of the minimal supersymmetric standard model (MSSM) consists
of five physical Higgs bosons, which offer a variety of channels for their
experimental search. The present study aims to further our understanding of the
Tevatron reach for MSSM Higgs bosons, addressing relevant theoretical issues
related to the SUSY parameter space, with special emphasis on the radiative
corrections to the down--quark and lepton couplings to the Higgs bosons for
large $\tan\beta$. We performed a computation of the signal and backgrounds for
the production processes $W\phi$ and $b \bar{b} \phi$ at the upgraded Tevatron,
with $\phi$ being the neutral MSSM Higgs bosons. Detailed experimental
information and further higher order calculations are demanded to
confirm/refine these predictions.


title:
Probing hadron structure and strong interactions with inclusive
  semileptonic decays of B mesons

abstract:
  The study of inclusive semileptonic decays of $B$ mesons is analyzed from the
viewpoint of probing hadron structure and strong interactions. General formulas
for the differential decay rates are given in terms of the structure functions
in arbitrary frame of reference, taking into account the finite charged lepton
mass. These formulas can be used for structure function measurements. The
behavior of the structure functions is shown to contain information on the
constitution of the $B$ meson and the dynamics of strong interactions.
Measurements of the structure functions would reveal the existence of a
point-like $b$ quark in the $B$ meson, establish the spin 1/2 nature of the $b$
quark, and identify the $b$ quantum number of the $B$ meson. These measurements
would determine the $b$ quark distribution function, and allow new insight into
the nature of confinement. The $b$ quark distribution function can also be
extracted directly through the measurements of the decay distributions with
respect to the scaling variable $\xi_+$.


title: Low-energy solar anti-neutrinos

abstract:
  If neutrino conversions within the Sun result in partial polarization of
initial solar neutrino fluxes, then a new opportunity arises to observe the
anti-\nu_e's in future neutrino experiments in the low energy region (such as
BOREXINO or HELLAZ) and thus to probe the Majorana nature of the neutrinos. The
\nu_e -> anti-\nu_e conversions may take place for low energy solar neutrinos
while being unobservable at the Kamiokande and Super-Kamiokande experiments.