title:
Probability of Color Rearrangement at Partonic Level in Hadronic W^+W^-
  Decays

abstract:
  A strict method to calculate the color rearrangement probability at partonic
level in hadronic $W^+W^-$ decays is proposed. The color effective Hamiltonian
$H_c$ is constructed from invariant amplitude for the process $e^+e^- \to
W^+W^- \to q_1\bar{q}_2 q_3\bar{q}_4+ng$ (n=0, 1, 2, ...) and is used to
calculate the cross sections of various color singlets and the color
rearrangement probability. The true meaning of the color rearrangement is
clarified and its difference from color interference is discussed.


title: Resonant CP Violation in Higgs Production, Mixing and Decay

abstract:
  CP violation induced by resonant transitions of a scalar to a pseudoscalar
intermediate state is analyzed within a gauge-invariant resummation approach
based on the pinch technique. Necessary conditions governing the resonant
enhancement of CP violation in transition amplitudes are derived. The results
of this study are then applied to describe the indirect mixing of a CP-even
Higgs scalar, $H$, with a CP-odd Higgs particle, $A$, in two-Higgs doublet
models. CP violation through $HA$ mixing in high-energy $pp$, $e^+e^-$ and
$\mu^+\mu^-$ scatterings are estimated to be fairly large for a natural choice
of kinematic parameters. Low-energy constraints originating from experimental
upper bounds on the neutron electric dipole model are implemented in this
analysis.


title:
Analyticity and Minimality of Nonperturbative Contributions in
  Perturbative region for $\bar\alpha_s$

abstract:
  It is shown, that the possibility of a freezing of QCD running coupling
constant at zero in the approach with "forced analyticity" can not be in accord
with Schwinger-Dyson equation for gluon propagator. We propose to add to the
analytic expression the well-known infrared singular term $1/q^2$ as well as
pole term corresponding to "excited gluon". With this example we formulate the
principle of minimality of nonperturbative contributions in perturbative
(ultraviolet) region, which allows us to fix ambiguities in introduction of
nonperturbative terms and maintain the finiteness of the gluon condensate. As a
result we obtain estimates of the gluon condensate, which quite agree with
existing data. The nonzero effective mass of the "excited gluon" leads also to
some interesting qualitative consequences.


title:
New vector bosons in the electroweak sector: a renormalizable model with
  decoupling

abstract:
  A linear realization of a model of dynamical electroweak symmetry breaking
describing additional heavy vector bosons is proposed. The model is a SU(2)_L x
U(1) x SU(2)_L' x SU(2)_R' gauge theory, breaking at some high scale u to
SU(2)_weak x U(1)_Y and breaking again in the standard way at the electroweak
scale v to U(1)_(em). The model is renormalizable and reproduces the Standard
Model in the limit u\to infinity. This decoupling property is shown to hold
also at the level of radiative corrections by computing, in particular, the
epsilon parameters.


title: High-energy photon splitting in a strong Coulomb field

abstract:
  The helicity amplitudes of the high-energy photon splitting in the external
Coulomb field are obtained exactly in the parameter $\al$. The cases of
screened and unscreened potentials are investigated. The consideration is based
on the quasiclassical approach, valid for small angles between all photon
momenta. New representation of the quasiclassical electron Green function is
exploited. General expressions obtained are analyzed in detail for the case of
large transverse momenta of both final photons compared to the electron mass.


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_{\n_\m} \sim 3\cdot 10^{-3} $eV as
preferred by the MSW solution to the solar neutrino deficit.


title:
Dark matter constraints on the parameter space and particle spectra in
  the nonminimal SUSY standard model

abstract:
  We investigate the dark matter constraints for the nonminimal SUSY standard
model (NMSSM). The cosmologically restricted mass spectra of the NMSSM are
compared to the minimal SUSY standard model (MSSM). The differences of the two
models concerning the neutralino, sfermion and Higgs sector are discussed. The
dark matter condition leads to cosmologically allowed mass ranges for the SUSY
particles in the NMSSM: m_{\tilde{\chi}^0_1} < 300 GeV, m_{\tilde{e}_R} < 300
GeV, 300 GeV < m_{\tilde{u}_R} < 1900 GeV, 200 GeV < m_{\tilde{t}_1} < 1500
GeV, 350 GeV < m_{\tilde{g}} < 2100 GeV and for the mass of the lightest scalar
Higgs m_{S_1} < 140 GeV.


title: Chiral Perturbation Theory and Threshold Corrections

abstract:
  I give a short overview of Chiral Perturbation Theory, its underlying
assumptions and underpinnings. A few examples are included.


title:
From $b \to s \gamma$ to the LSP Detection Rates in Minimal String
  Unification Models

abstract:
  We exploit the measured branching ratio for $b \rightarrow s\gamma$ to derive
lower limits on the sparticle and Higgs masses in the minimal string
unification models. For the LSP('bino'), chargino and the lightest Higgs, these
turn out to be 50, 90 and 75 GeV respectively. Taking account of the upper
bounds on the mass spectrum from the LSP relic abundance, we estimate the
direct detection rate for the latter to vary from 10^{-1} to 10^{-4}
events/kg/day. The muon flux, produced by neutrinos from the annihilating
LSP's, varies in the range 10^{-2} - 10^{-9} muons/m^2/day.


title: Consistency of the Baryon-Multimeson Amplitudes for Large-N_c QCD

abstract:
  We study the pion-baryon scattering process $\pi+B \to (n-1)\pi+B$ in a QCD
theory with a large number (N_c) of colors. It is known that this scattering
amplitudes decreases with N_c like N_c^{1-n/2}, and that its individual tree
diagrams grow like N_c^{n/2}. The only way these two can be consistent is for
n-1 powers of N_c to be cancelled when the Feynman diagrams are summed. We
prove this to be true in tree order for any n.


title: Reply Comment on "Meson Masses in Nuclear Matter"

abstract:
  We reply to the Comment by Hatsuda and Lee on our recent paper "Meson Masses
in Nuclear Matter" (Phys.Rev.Lett. 78, 1010, (1997)). We argue that, contrary
to the claim in the Comment, the short distance operator product expansion is
not applicable for calculation of meson mass shifts in nuclear matter, since
they are determined by long distance physics. We also remark that the
suggestion made in the Comment that we overlooked in our paper the mean field
description of the mass shifts of low-q mesons is perhaps due to a
misunderstanding.


title: Summary and Outlook

abstract: This will be more of an outlook than a summary ...


title:
New Solution to Doublet-Triplet Splitting Problem in SU(N) SUSY GUTs:
  Towards an Unification of Flavour

abstract:
  The missing VEV solution to the doublet-triplet splitting problem in general
SU(N) SUSY GUTs is found. Remarkably enough, it requires a strict equality of
numbers of the fundamental colours and flavours in SU(N) and for the even-order
groups (N=2k) gives the predominant breaking channel $SU(N) \to
SU(k-1)_c\otimes SU(k-1)_f\otimes SU(2)_w\otimes U(1)\otimes U(1)'$ in the
parameter natural area. The flavour subsymmetry breaking owing to some generic
string inspired extra symmetries of the Higgs superpotential appears not to
affect markedly the basic adjoint vacuum configuration in the model. Thus the
both salient features of SM just as an interplay between colours and flavours
(or families for due assignment of quarks and leptons) so the doublet structure
of the weak interactions could be properly understood and accommodated in the
framework of the minimal SU(8) model. Among its predictions the most crucial
one belongs to the existence on the TeV scale just three families of
pseudo-Goldstone bosons and their superpartners 3(5+\bar 5) + SU(5)-singlets
which noticeably improve the unification picture of MSSM.


title: Vector boson production in hadronic collisions

abstract:
  We consider the production of $\gamma^*, W$ and $Z$ vector bosons in
hadron-hadron collisions in perturbative QCD. We present results from a new
numerical program which gives a full description of the production of the
vector bosons and of their decay products. At small $\qt$ the calculation
includes resummation of large logarithms and non-perturbative effects. The
resummation is matched with the full $O(\alpha_S)$ calculation. In addition,
the program correctly reproduces the known $O(\alpha_S)$ cross section when
integrated over $\qt$. Besides presenting results for $W$ and $Z$ production at
the Tevatron, we also review constraints on the non-perturbative functions
using fixed target data on lepton pair production, and make several
observations on this topic.


title: Nonabelian Cut Diagrams

abstract:
  Symmetrization of bosonic wave functions produces bunching and low
temperature phenomena like Bose-Einstein condensation, superfludity,
superconductivity, as well as laser. Since probability is conserved, one might
expect such bunchings at one place would lead to a depletion or a destructive
interference at another place. This indeed takes place in high-energy
scatterings, leading to cancellations between Feynman diagrams with permuted
(real or virtual) boson lines. It is such cancellation that allow the Froissart
bound to be obeyed, and the meson-baryon amplitudes in large-N_c QCD to be
consistent. These lectures review the derivation and some of the applications
of ``nonabelian cut diagrams'', which are resummation of Feynman diagrams, but
with these interference effects explicitly incorporated. Unlike the traditional
method where cancellations occur between Feynman diagrams, making it necessary
to compute each diagram to subleading orders, destructive interference has been
taken care of from the start in nonabelian cut diagrams. No further
cancellation takes place, so each nonabelian cut diagram may be computed only
in the leading order.


title:
e+ e- Annihilation into Hadrons at LEP2 in the Presence of the Anomalous
  DESY Positron-Jet Event Phenomenon

abstract:
  We discuss the allowed parameter regime in the coupling-mass plane implied by
the existing LEP2 data on e+ e- -> hadrons at 172.3 GeV for the leptoquark
interpretation of the anomalous DESY positron-jet events for four different
models of the leptoquark charges and chiral couplings to quarks, for both a
loose cut on s'/s and a tight cut on s'/s. We find that this interpretation of
the DESY phenomenon is still consistent with the LEP2 data although, for vector
leptoquarks, a significant regime of the relevant parameter space is already
excluded.


title: Periodic Instanton Bifurcations and Thermal Transition Rate

abstract:
  It is shown that periodic instanton solutions may have bifurcations which
qualitatively change the behaviour of the finite temperature transition rate.
These bifurcations are studied numerically in a quantum mechanical model and in
the massive two-dimensional sigma model with the Skyrme term. General rules
which determine the behaviour of periodic instantons near bifurcations are
derived and applied to the Electroweak Theory.


title: Top Quark Physics: Future Measurements

abstract:
  (Report of the Top Physics working group at the 1996 DPF/DPB Snowmass
workshop, to appear in the proceedings). We discuss the study of the top quark
at future experiments and machines. Top's large mass makes it a unique probe of
physics at the natural electroweak scale. We emphasize measurements of the top
quark's mass, width, and couplings, as well as searches for rare or nonstandard
decays, and discuss the complementary roles played by hadron and lepton
colliders.


title:
Flavour changing top decays in supersymmetric extensions of the standard
  model

abstract:
  Flavour changing top decays $t \to c Z^0, t \to c g$ and $t \to c \gamma$ are
predicted with invisible rates within the standard model and may represent a
window on new physics. We consider these processes in supersymmetric extensions
of the standard model and we show that observable rates can be obtained only if
the SUSY breaking is non universal and flavour dependent.


title: High Power n of m_b in Beauty Widths and n=5 -> oo Limit

abstract:
  The leading term in the semileptonic width of heavy flavor hadrons depends on
the fifth power of the heavy quark mass. We present an analysis where this
power can be self-consistently treated as a free parameter n and the width can
be studied in the limit n -> oo. The resulting expansion elucidates why the
small velocity (SV) treatment is relevant for the inclusive semileptonic b->c
transition. The extended SV limit (ESV limit) is introduced. The leading terms
in the perturbative alpha_s expansion enhanced by powers of n are automatically
resummed by using the low-scale Euclidean mass. The large-n treatment explains
why the scales of order m_b/n are appropriate. On the other hand, the scale
cannot be too small since the factorially divergent perturbative corrections
associated with running of alpha_s show up. Both requirements are met if we use
the short-distance mass normalized at a scale around m_b/n \sim 1 GeV. A
convenient definition of such low-scale OPE-compatible masses is briefly
discussed.


title: Unity of Supersymmetry Breaking Models

abstract:
  We examine the models with gauge group U(1)^{k-1}\times\prod_{i=1}^k SU(n_i),
which are obtained from decomposing the supersymmetry breaking model of
Affleck, Dine and Seiberg containing an antisymmetric tensor field. We note
that all of these models are distinct vacua of a single SU(N) gauge theory with
an adjoint superfield. The dynamics of this model may be analyzed using the
duality of Kutasov and Schwimmer and the deconfinement trick of Berkooz. This
analysis leads to a simple picture for supersymmetry breaking for k=2,
complementing that of previous work. We examine the flat directions of these
models, and give straightforward criteria for lifting them, explaining the
requisite peculiar form of the superpotential. For all cases with k>2, the
duality argument fails to give supersymmetry breaking dynamics, and we identify
a class of problematic flat directions, which we term 2m-baryons. We study in
some detail the requirements for lifting these directions, and uncover some
surprising facts regarding the relationship between R-symmetry and
supersymmetry breaking in models with several gauge groups.


title: Compactifications of M-theory and their Phenomenological Consequences

abstract:
  We compactify the M-theory proposed by Horava and Witten on a Calabi-Yau
manifold with boundary $S_1/Z_2$. A no-scale-like K\"ahler potential, the
superpotential, and the gauge kinetic function are obtained in this
4-dimensional $E_6\times E_8$ model. We also study the general phenomenological
consequences of the resulting M-theory-inspired model, which may include very
light gravitinos, axions and axinos.


title:
Electroweak-Scale Excess Cross-Sections in the Sextet Quark ``Standard
  Model''

abstract:
  When the Higgs sector of the standard model is replaced by a flavor doublet
of color sextet quarks, dynamical electroweak symmetry breaking occurs, with
the electroweak scale identified as the sextet chiral scale. Above the
electroweak scale QCD is almost scale-invariant, leading to the high-momentum
enhancement of both the sextet chiral condensate and instanton interactions.
The instanton interactions combine with the sextet condensate to produce
electroweak scale chirality violating processes in both the triplet and sextet
sectors. If the enhancement is sufficient, an electroweak scale top mass can be
produced and the $\eta_6$ axion mass can be raised, potentially providing a
consistent description of both Strong CP conservation and electroweak-scale CP
violation. The instanton interactions also produce electroweak scale chirality
violating scattering processes for light quarks and additionally modify QCD
evolution at the electroweak scale. Such effects could explain the excesses in
the DIS cross-section at HERA and jet cross-sections at the Tevatron.


title: On the QCD Sum Rule Determination of the Strange Quark Mass

abstract:
  In the QCD Sum Rule determination of $m_s$ using the two-point correlator of
divergences of $\Delta S=1$ vector currents, the final uncertainty on $m_s$ is
mainly due to the hadronic spectral function. Using a specific parameterization
which fully takes into account the available experimental data on the $K \pi$
($I=1/2, J^P=0^+)$ system, characterized by the presence of a relevant
nonresonant component in addition to the resonant one, we find ${\bar m_s}(1
GeV)\ge 120 MeV$. In particular, varying only the parameters describing the
nonresonant $K \pi$ component and $\Lambda_{\bar {MS}}^{n_f=3}$ we obtain
${\bar m_s}(1 GeV)=125 - 160 MeV$. This result is smaller than analogous ones
obtained by using a parameterization in terms of only resonant states. We
discuss how to systematically improve the determination of $m_s$ by this
method.


title: Dissipation and Fluctuation at the Chiral Phase Transition

abstract:
  Utilizing the Langevin scenario for the linear sigma model we investigate the
effect of friction and white noise on the evolution and stability of collective
pionic fields in heavy ion collisions. We find that the smaller the volume the
more stable pionic fluctuations become (the avergae mass increases). On the
other hand the variance of the mass square increases even more, so for a system
preheated in 10 fm3 volume individual trajectories do become unstable during a
rapid one dimensional expansion in contrast to the ensemble averaged solution.
This result supports the idea of looking for disoriented chiral condensate
(DCC) formation in individual events.


title:
On the Multiplicity Distributions of Charged Secondaries in the
  Collisions of Relativistic Nuclei

abstract:
  Multiplicities of charged secondary hadrons in the relativistic
nucleus-nucleus collisions in a wide energy range are analysed on the basis of
partial stimul- ting emission and cluster cascading models. The experimental
data are obtained by means of the two metre propane bubble chamber of JINR
(Dubna). The results are compared with the correponding data for pp and anti
pp-colli- sions at higher energies. It is shown that the regularities in pp and
anti pp- interactions at high energies and wide energy range and in
nucleus-nucleus interactions at relatively low energies per nucleon and
narrower energy range are similar.


title:
Extracting the Proton ubar content from pp->Direct Photon plus Jet Cross
  Sections

abstract:
  An analysis procedure is proposed to measure the antiquark distributions in
the proton over the region 0.01 < x < 0.1. The procedure involves the
measurement of high p_t asymmetric direct photon and jet final states in pp
interactions. This measurement can be made at the RHIC collider running in pp
mode at an energy of sqrt(s)=500 GeV/c. This analysis identifies a region of
phase space where the contribution from quark-antiquark annihilation
uncharacteristically approaches the magnitude of the contribution from the
leading process, quark-gluon Compton scattering. The forward-backward angular
asymmetry in the parton center of mass is sensitive to the antiquark content of
the proton and the ubar parton density function can be extracted.


title: New Class of Quark Mass Matrix and Calculability of Flavor Mixing Matrix

abstract:
  We discuss a new general class of mass matrix ansatz that respects the
fermion mass hierarchy and calculability of the flavor mixing matrix. This is a
generalization and justification of the various specific forms of the mass
matrix by successive breaking of the maximal permutation symmetry. By
confronting the experimental data, a large class of the mass matrices are shown
to survive, while certain specific cases are phenomenologically ruled out. Also
the CP-violation turns out to be maximal, when the phase of the (1,2) element
of the mass matrix is $\pi /2$.


title: Comment on Plaga's analysis of neutrino scattering Charm II data

abstract:
  We argue that the inclusion of the flavour-changing charged currents in the
analysis of the Charm II data on neutrino- electron scattering could
substantially change a fit of the effective couplings and makes impossible to
draw any final conclusion on the Dirac or Majorana nature of neutrinos.


title:
Radiative energy loss of high energy quarks in finite-size nuclear
  matter and quark-gluon plasma

abstract:
  The induced gluon radiation of a high energy quark in a finite-size QCD
medium is studied. For a sufficiently energetic quark produced inside a medium
we find the radiative energy loss $\Delta E_{q}\propto L^{2}$, where L is the
distance passed by quark in the medium. It has a weak dependence on the initial
quark energy $E_{q}$. The $L^{2}$ dependence turns to $L^{1}$ as the quark
energy decreases. Numerical calculations are performed for a cold nuclear
matter and a hot quark-gluon plasma. For a quark incident on a nucleus we
predict $\Delta E_{q}\approx 0.1 E_{q}(L/10 fm)^{\beta}$, with $\beta$ close to
unity.


title:
Reparameterization Invariance to all Orders in Heavy Quark Effective
  Theory

abstract:
  Heavy Quark Effective Theory splits a heavy quark momentum into a large fixed
momentum and a variable residual momentum, p = m_Q v + k. It thereby suffers a
redundancy of description corresponding to small changes in the choice of the
fixed velocity, v. The fact that full QCD is manifestly v-independent should
lead to a non-trivial constraint on the form of the effective theory, known as
Reparameterization Invariance. For spin-1/2 quarks, the precise form of the
constraint and its solution at the level of the effective lagrangian have
proven to be rather subtle, and the original proposal by Luke and Manohar has
been questioned. In this paper I employ a version of Heavy Quark Effective
Theory containing the ``anti-particle'' field as a non-propagating auxiliary
field, which greatly simplifies keeping track of v-dependence. This permits a
very simple derivation of Reparameterization Invariance from first principles.
The auxiliary field can also be integrated out to return to the standard
formulation of the effective theory, but with the effective lagrangian now
satisfying the full reparameterization constraint. I compare this result with
earlier proposals.


title:
R-parity-violating SUSY effects and signals in single top production at
  the Tevatron

abstract:
  We discuss single top quark production via u^i+\bar d^j \to t+\bar b at the
Fermilab Tevatron in the minimal supersymmetric model with R-parity violation.
We find that within the allowed range of coupling constants, the lepton-number
violating couplings can give rise to observable effects when the slepton mass
lies in a specific narrow range. For the baryon-number violating couplings, the
contribution to the production rate can be quite large in the presently allowed
range of the coupling constants. We show that the measurement of single top
production at the upgraded Tevatron can be used to constrain a linear
combination of products of the R-parity violating couplings.


title: Soft gluon effects on lepton pairs at hadron colliders

abstract:
  With a large integrated luminosity expected at the Tevatron, a
next-to-leading order (NLO) calculation is no longer sufficient to describe the
data which yield the precision measurement of $M_W$, etc. Thus, we extend the
Collins-Soper-Sterman resummation formalism, for on-shell vector boson
production, to correctly include the effects of the polarization and the width
of the vector boson to the distributions of the decay leptons. We show how to
test the rich dynamics of the QCD multiple soft gluon radiation, for example,
by measuring the ratio $R_{CSS} \equiv \frac{\sigma (Q_T>Q_T^{\min})}{\sigma
_{Total}}$. ($Q_T$ is the transverse momentum of the vector boson.) We conclude
that both the total rates and the distributions of the lepton charge asymmetry
predicted by the resummed and the NLO calculations are different when kinematic
cuts are applied.


title:
Probing Anomalous Wtb Coupling via Single Top Production at TeV Energy
  $\gamma$ e Colliders

abstract:
  Results of complete tree level calculations of the single top production
reaction $\gamma e \to \nu \bar{t} b$ at the Next Linear Collider, including
the contribution of anomalous operators to the Wtb coupling are presented. The
sensitivity for probing the structure of the Wtb coupling in a model
independent way is analyzed and found to be significantly higher than for
comparable measurements at the Tevatron.


title: A Phenomenological Analysis of Heavy Hadron Lifetimes

abstract:
  A phenomenological analysis of lifetimes of bottom and charmed hadrons within
the framework of the heavy quark expansion is performed. The baryon matrix
element is evaluated using the bag model and the nonrelativistic quark model.
We find that bottom-baryon lifetimes follow the pattern
$\tau(\Omega_b)\simeq\tau(\Xi_b^-)>\tau(\Lambda_b)\simeq\tau(\Xi_b^0)$.
However, neither the lifetime ratio $\tau(\Lambda_b)/\tau( B_d)$ nor the
absolute decay rates of the $\Lambda_b$ baryon and $B$ mesons can be explained.
One way of solving both difficulties is to allow the presence of linear $1/m_Q$
corrections by scaling the inclusive nonleptonic width with the fifth power of
the hadron mass $m_{H_Q}$ rather than the heavy quark mass $m_Q$. The hierarchy
of bottom baryon lifetimes is dramatically modified to
$\tau(\Lambda_b)>\tau(\Xi_b^-)>\tau(\Xi_b^0)>\tau( \Omega_b)$: The
longest-lived $\Omega_b$ among bottom baryons in the OPE prescription now
becomes shortest-lived. The replacement of $m_Q$ by $m_{H_Q}$ in nonleptonic
widths is natural and justified in the PQCD-based factorization approach
formulated in terms of hadron-level kinematics. For inclusive charmed baryon
decays, we argue that since the heavy quark expansion does not converge, local
duality cannot be tested in this case. We show that while the ansatz of
substituting the heavy quark mass by the hadron mass provides a much better
description of the charmed-baryon lifetime {\it ratios}, it appears unnatural
and unpredictive for describing the {\it absolute} inclusive decay rates of
charmed baryons, contrary to the bottom case.


title: Top Mesons

abstract:
  The possibility of formation for a bound state of a $t$ quark and a lighter
one is investigated using potential model predictions and heavy quark effective
theory approach. Resulting estimates for the 1S--2S splitting of the energy
levels are compared to the total top decay width $\Gamma_t$ . As for the case
of toponium, our conclusions show that the probability of formation for
T-mesons is negligibly small due to the high top mass value.


title: Thermal photon production rate from non-equilibrium quantum field theory

abstract:
  In the framework of closed time path thermal field theory we investigate the
production rate of hard thermal photons from a QCD plasma away from
equilibrium. Dynamical screening provides a finite rate for chemically
non-equilibrated distributions of quarks and gluons just as it does in the
equilibrium situation. Pinch singularities are shown to be absent in the real
photon rate even away from equilibrium.


title: Theoretical Aspects of Higgs Hunting at LHC

abstract:
  I discuss recent developments in the theoretical study of Higgs search at
LHC.


title: CPT Violation, Strings, and Neutral-Meson Systems

abstract:
  This talk provides a short overview of recent results on possible CPT
violation and some associated experimental signatures.


title:
Conformal symmetry on the light cone and nonleading twist distribution
  amplitudes of massive vector meson

abstract:
  A complete set of asymptotic three particle light cone distribution
amplitudes of twist 3 and 4 for a transversely polarized massive vector meson
built out of massless current quarks is constructed. The method used is based
on a modified conformal projectors technique which allows to handle kinematical
corrections due to a finite hadron mass. Consequences of our finding for the
\rho -meson hard diffractive electroproduction and \gamma \rho \pi form factor
are discussed. Our results may imply a breakdown of OPE for some exclusive
processes beyond the leading twist level.


title: Neutrino Mass and Mixing in the Universal Yukawa Coupling Framework

abstract:
  We present an analysis of neutrino oscillations which are consistent with
current solar, atmospheric and terrestrial experiments in a framework with
three neutrino mixing. The solutions satisfying these experiments have the
large mixing (not maximal mixing) between electron neutrino- muon neutrino or
muon neutrino-tau neutrino in m3 to be about several eV, where m3 is the
heaviest neutrino mass. From these results, we conjecture a form for the mass
matrices of charged lepton and neutrino which are described by the universal
Yukawa coupling with small violations.


title: Gluon Pair Production in the Quasi-Multi-Regge Kinematics

abstract:
  To find the region of applicability of the leading log(1/x) approximation for
parton distributions in the small x region and to fix the argument of the QCD
running coupling it is necessary to know radiative corrections to the kernel of
the BFKL equation. The next-to-leading corrections to the BFKL kernel are
expressed in terms of the two-loop correction to the gluon Regge trajectory,
one-loop correction to the Reggeon-Reggeon-gluon vertex, and contributions from
two-gluon and quark-antiquark production in the quasi-multi-Regge kinematics.
We calculate differential and total cross sections of the two gluon production.
Differential cross section can be applied for description of two jet production
in the quasi-multi-Regge kinematics; the total cross section defines
corresponding correction to the BFKL kernel. To escape the infrared
divergencies we use dimensional regularization of the Feynman integrals.


title: Rare decays B -> (K, K*) (l+ l-, nu bar{nu}) in the quark model

abstract:
  Long-distance effects in exclusive rare semileptonic transitions B -> (K, K*)
are analysed within a relativistic quark model. The meson transition form
factors, describing the meson amplitudes of the effective weak Hamiltonian, are
calculated within the dispersion formulation of the quark model as relativistic
double spectral representations through the wave functions of the initial and
final mesons. The dilepton spectra and lepton asymmetries are considered within
the framework provided by the Standard Model. It is found that, while the
non-resonant decay rates are very sensitive to quark model parameters, the
model dependence of the predicted dilepton forward-backward and lepton
polarization asymmetries is remarkably small, providing only an overall ~10%
uncertainty.


title: Nonequilibium Neutrino Oscillations and Primordial Nucleosynthesis

abstract:
  We studied nonequilibrium oscillations between left-handed electron neutrinos
and nonthermalized sterile neutrinos. The exact kinetic equations for
neutrinos, written in terms of neutrino density matrix in momentum space were
analyzed. The evolution of neutrino density matrix was numerically calculated.
This allowed to study precisely the evolution of the neutrino number densities,
energy spectrum distortion and the asymmetry between neutrinos and
antineutrinos for each momentum mode. Both effects of distortion and asymmetry,
which cannot be accounted for correctly when working in terms of particle
densities and mean energies, and the depletion of electron neutrino state have
been proved considerable for a certain range of oscillation parameters. The
influence of nonequilibrium oscillations on primordial nucleosynthesis was
calculated. Cosmologically excluded regions for oscillation parameters were
obtained.


title:
Low x Behaviour of the Isovector Nucleon Polarized Structure Function
  and the Bjorken Sum Rule

abstract:
  The combination g_1^p(x) - g_1^n(x) is derived from SLAC data on polarized
proton and deuteron targets, evaluated at Q^2 = 10 GeV^2, and compared with the
results of SMC experiment. The agreement is satisfactory except for the points
at the three lowest x, which have an important role in the SMC evaluation of
the l.h.s. of the Bjorken sum rule.


title:
Study of Baryon Antibaryon Rapidity Correlation in e^+e^- Annihilation
  by Quark Combination Model

abstract:
  We use Quark Combination Model to study baryon antibaryon rapidity
correlation in e^+e^- annihilation and compare our predictions with the
available data. We find that these results and relevant properties are all
consistent with data. So the evidence to rule out Quark Combination Model which
has long been cited in literatures does not exist.


title:
Mixing-induced CP Asymmetries in Radiative B Decays in and beyond the
  Standard Model

abstract:
  In the Standard Model (SM) the photon in radiative $\bar B^0$ and $\bar B_s$
decays is predominantly left-handed. Thus, mixing induced CP asymmetries in
$b\to s\gamma$ and $b\to d\gamma$ are suppressed by $m_s/m_b$ and $m_d/m_b$,
respectively, and are very small. In many extensions of the SM, such as the
left-right symmetric model (LRSM), SU(2)xU(1) models with exotic fermions and
SUSY, the amplitude of right-handed photons grows proportional to the virtual
heavy fermion mass, which can lead to large asymmetries. As an example, in the
LRSM, asymmetries larger than 50% are possible even when radiative decay rate
measurements agree with SM predictions.


title: Solitons in the supersymmetric extensions of the Standard Model

abstract:
  All supersymmetric generalizations of the Standard Model allow for stable
non-topological solitons of the Q-ball type which may have non-zero baryon and
lepton numbers, as well as the electric charge. These solitons can be produced
in the early Universe, can affect the nucleosynthesis, and can lead to a
variety of other cosmological consequences.


title: CP Violating B Decays in the Standard Model and Supersymmetry

abstract:
  We study the uncertainties of the Standard Model (SM) predictions for CP
violating B decays and investigate where and how supersymmetric (SUSY)
contributions may be disentangled. The first task is accomplished by letting
the relevant matrix elements of the effective Hamiltonian vary within certain
ranges. The SUSY analysis makes use of a formalism which allows to obtain
model-independent results. We show that in some cases it is possible a) to
measure the CP B-\bar{B} mixing phase and b) to discriminate the SM and SUSY
contributions to the CP decay phases. The golden-plated decays to this purpose
are the B \to \phi K_S and B \to K_S \pi^0 channels.


title: The high-Q^2 Hera anomaly and supersymmetric unification

abstract:
  We discuss an initial condition on the superpotential couplings of an SU(5)
theory which allows the R-violating term L d^c Q but avoids the simultaneous
presence of L L e^c + d^c d^c u^c. This same condition keeps under control the
products of pairs of different couplings lambda_{ijk} L_i d^c_j Q_k, which are
more strongly constrained by flavour-changing-neutral-current limits. In our
view, this observation makes relatively more plausible the interpretation of
the high-Q^2 Hera anomaly, if real, as caused by squark production.


title:
Global Analysis for Probing Electroweak Symmetry Breaking Mechanism at
  High Energy Colliders

abstract:
  We review our recent global analysis for probing the electroweak symmetry
breaking (EWSB) mechanism by the universal effective Lagrangian description.
After summarizing and commenting upon the current bounds for the EWSB
parameters, we focus on testing them at the forthcoming high energy colliders
such as the CERN LHC and the future linear colliders. We develop a precise
electroweak power counting method (a la Weinberg) and formulate the
longitudinal-Goldstone boson equivalence as a necessary criterion for
sensitively probing the EWSB sector. Armed with these, we systematically
estimate and classify the contributions of {all} next-to-leading order (NLO)
bosonic operators to various scattering processes at the high energy colliders.
The experimental signatures at these colliders are also analyzed. Furthermore,
the {complementarity} of different scattering processes via different colliders
for a complete probe of all these NLO effective operators is demonstrated.


title: Measuring the CP Angle \beta in Hadronic b\to s Penguin Decays

abstract:
  Asymmetric e^+e^- colliders running on the \Upsilon(4S) (B factories) will
much more readily measure CP-violating asymmetries in the decays of B_d^0 and
B^\pm mesons than in the decays of B_s^0 mesons. As such, they will seemingly
not be able to probe new phases in Bs-Bs(bar) mixing, i.e. in b\to s
transitions. However, by measuring the CP angle \beta via b \to s hadronic
penguin decays such as B_d^0 \to \eta'\ks and B_d^0 \to\phi\ks, and comparing
its value to that obtained in B_d^0 \to\Psi\ks, it is possible to detect the
presence of new physics in the b\to s flavour-changing neutral current. Recent
CLEO results are encouraging in this regard. They suggest that the branching
ratio of the b\to s penguin decay B_d^0 \to \eta'\ks is anomalously large,
about 4 \times 10^{-5}, which will make it much easier to search for new
physics in b\to s transitions.


title:
Bound on V+A admixture in the b -> c current from inclusive vs.
  exclusive semileptonic decays of B mesons

abstract:
  An admixture of a right-handed $b \to c$ current in the semileptonic weak
decays of the $B$ mesons would give a significantly different contribution to
the inclusive rate of the decays $B \to l \nu X_c$ as compared to the exclusive
decay $B \to D^* l \nu$ at zero recoil. Thus a difference in the values of
$|V_{cb}|$ extracted from the data on these two types of decay would measure
such admixture. The present marginal mismatch in determination of $|V_{cb}|$ by
the two methods can be interpreted as corresponding to $g_R/g_L \approx 0.14
\pm 0.18$.


title:
$\sigma_L/\sigma_T$ in the $\rho^0$ - meson diffractive
  electroproproduction

abstract:
  The background due to the direct diffractive dissociation of the photon into
the $\pi^+\pi^-$-pair to the "elastic" diffractive $\rho^0$-meson production in
electron-proton collisions is calculated. At large $Q^2$ the interference
between resonant and non-resonant $\pi^+ \pi^-$ production changes the
$\sigma^L/\sigma^T$ ratio with the mass of the $2\pi$ (i.e. $\rho^0$-meson)
state.


title: Leptoquarks and vector-like strong interactions at the TeV scale

abstract:
  In a vector-like extension of the minimal standard model with mirror fermions
leptoquarks can be bound states of fermion-mirror-fermion pairs held together
by a new strong interaction at the TeV scale. The small couplings of
leptoquarks to light fermion pairs arise due to mixing. The large $Q^2$ event
excess at HERA and also the high $E_T$ jet excess at Tevatron can potentially
be explained.


title:
J/Psi suppressions in a thermally equilibrating quark-gluon plasma at
  RHIC

abstract:
  We estimate the survival probability of $J/{\psi}$ in relativistic heavy-ion
collisions, using both short-distance QCD and nuclear absorption mechanism. The
suppression is found to be almost 100 percent for a thermally equilibrating
quark-gluon plasma. The measurement of such a huge suppression of $J/{\psi}$
may suggest the existence of a deconfined partonic medium, possibly a
thermalised quark-gluon plasma, at RHIC.


title: The Light-Cone nonperturbative dynamics of meson wave functions

abstract:
  The light-cone Hamiltonian, incorporating the nonperturbative dynamics of the
$q\bar q$ system connected by the string is solved numerically. The spectrum is
shown to coincide with that of the center-of-mass Hamiltonian within the
accuracy of computation, displaying the expected degeneracies of the string
states, but an overall shift due to different treatment of Z-graphs is
obtained. The nonperturbative wave functions are calculated directly from the
light-cone Hamiltonian for the first time, thus allowing the explicit
estimation of nonperturbative effects in the parton model language. In this way
one obtains the string contribution to the parton distributions and in the
formfactors and structure functions.


title: Experimental limits on complete positivity from the K-K system

abstract:
  Available data on measured observables allow deriving estimates for some of
the phenomenological parameters that characterize the time-evolution and decay
of the neutral kaon system based on the hypothesis of complete positivity. The
present experimental uncertainties are still too large to permit a full test of
complete positivity.


title: Radiative energy loss of hard parton jet in expanding quark-gluon fluid

abstract:
  The gluon radiation induced by multiple scattering of a hard parton in
expanding quark-gluon plasma is investigated. The radiative energy loss of hard
parton jet is shown to decrease considerably when angular size of extracted jet
goes up, but the fraction of loss survives even for the reasonable wide cone of
angles due to the coherent effects taking into account the rescattering of the
radiated gluons in the QCD medium. The possible application to the jet
quenching phenomenon in heavy ion collisions at LHC energies is discussed.


title:
Self-organized criticality and interacting soft gluons in deep-inelastic
  electron-proton scattering

abstract:
  It is suggested that the colorless systems of interacting soft-gluons in
large-rapidity-gap events are open dynamical complex systems in which
self-organized criticality and BTW-clusters play an important role. Theoretical
arguments and experimental evidences supporting such a statistical approach to
deep-inelastic scattering are presented.


title: Multiple inflation

abstract:
  Attempts at building an unified description of the strong, weak and
electromagnetic interactions usually involve several stages of spontaneous
symmetry breaking. We consider the effects of such symmetry breaking during an
era of primordial inflation in supergravity models. In cases that these occur
along flat directions at intermediate scales there will be a succession of
short bursts of inflation which leave a distinctive signature in the spectrum
of the generated scalar density perturbation. Thus measurements of the spectral
index can directly probe the structure of unified theories at very high energy
scales. An observed feature in the power spectrum of galaxy clustering from the
APM survey may well be associated with such structure. If so, this implies a
characteristic suppression of the secondary Doppler peaks in the angular power
spectrum of temperature fluctuations in the cosmic microwave background.


title: A Model Independent Construction of the Unitarity Triangle

abstract:
  In a large class of models, the only significant new physics effect on the CP
asymmetries in $B \to \psi K_S$ and $B \to \pi\pi$ decays is a new contribution
to the $B-\bar B$ mixing amplitude. This allows a model independent
construction of the CKM Unitarity Triangle (up to hadronic uncertainties).
Furthermore, the contributions to the mixing from the Standard Model and from
the new physics can be disentangled. A serious obstacle to this analysis is an
eightfold discrete ambiguity in solving for the angles of the triangle. Several
ways to reduce the ambiguity either by making further measurements, or by
making further assumptions about the nature of the new physics are described.


title: Probing the Electroweak Symmetry Breaking Sector with the Top Quark

abstract:
  A study on the effective anomalous interactions, up to dimension 5, of the
top quark with the electroweak gauge bosons is made in the non-linear Chiral
Lagrangian approach. Bounds on the anomalous dimension four terms are obtained
from their contribution to low energy data. Also, the potential contribution to
the production of top quarks at hadron colliders (the Tevatron and the LHC) and
the electron Linear Collider from both dimension 4 and 5 operators is analyzed.


title: Supersymmetric Lepton Flavor Violation at the NLC

abstract:
  Supersymmetric theories generally have new flavor violation sources in the
squark and slepton mass matrices. If significant lepton flavor violation
exists, selectron and smuon should be nearly degenerate. This leads to the
phenomenon of slepton oscillations, which is analogous to neutrino
oscillations, if sleptons are produced at the Next Linear Collider. The direct
slepton production at the Next Linear Collider provides a much more powerful
probe of lepton flavor violation than the current bounds from rare processes,
such as $\mu \to e\gamma$.


title: The Physics Capabilities of mu^+ mu^- Colliders

abstract:
  We summarize the potential of muon colliders to probe fundamental physics.
$W^+W^-$, \bar tt, and $Zh$ threshold measurements could determine masses to
precisions $\Delta M_W = 6$ MeV, $\Delta m_t = 70$ MeV, and $\Delta m_h = 45$
MeV, to test electroweak radiative corrections. With $s$-channel Higgs
production, unique to a muon collider, the Higgs mass could be pinpointed
($\Delta m_h < 1$ MeV) and its width measured. The other Higgs bosons of
supersymmetry can be produced and studied by three methods. If instead the $WW$
sector turns out to be strongly interacting, a 4 TeV muon collider is ideally
suited to its study.


title: Discovery Potential for New Phenomena

abstract:
  We examine the ability of future facilities to discover and interpret
non-supersymmetric new phenomena. We first explore explicit manifestations of
new physics, including extended gauge sectors, leptoquarks, exotic fermions,
and technicolor models. We then take a more general approach where new physics
only reveals itself through the existence of effective interactions at lower
energy scales. [Summary Report of the New Phenomena Working Group. To appear in
the Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High
Energy Physics - Snowmass96, Snowmass, CO, 25 June - 12 July 1996.]


title: Signatures of Extended Gauge Sectors in $e^+e^-\to \nu\bar\nu\gamma$

abstract:
  The ability of high energy $e^+e^-$ colliders to indirectly probe the
existence of heavy new charged gauge bosons via their exchange in the reaction
$e^+e^-\to \nu\bar\nu\gamma$ is investigated. It is shown that examination of
the resulting photon energy spectrum with polarized beams can extend the $W'$
search reach above the center of mass energy. [ To appear in the Proceedings of
the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics -
Snowmass96, Snowmass, CO, 25 June - 12 July 1996.]


title:
Electroweak properties of light mesons in relativistic hamiltonian
  dynamics

abstract:
  The calculation of lepton decay constants and electromagnetic form factors of
pion and kaon is performed in the framework of relativistic hamiltonian
dynamics. The different model wave function is used. Wave function parameters
are fixed from fit of mean square radius of meson. The internal quark structure
is taken into account by electromagnetic quark form factor and quark anomalous
magnetic moment. The pion and kaon form factors depend only weakly on model
wave function. Strong dependence of these values on quark anomalous magnetic
moment is obtained in the transfer momentum region of CEBAF experiments.


title: Quaternionic Mass Matrices and CP Symmetry

abstract:
  A viable formulation of gauge theory with extra generations in terms of
quaternionic fields is presented. For the theory to be acceptable, the number
of generations should be equal to or greater than 4. The quark-lepton mass
matrices are generalized into quaternionic matrices.It is concluded that
explicit CP violation automatically disappears in both strong- and
weak-interaction sectors.


title:
The $Q^2$ Dependence of the Sum Rules for Structure Functions of
  Polarized $e(\mu)N$ Scattering

abstract:
  The nonperturbative $Q^2$- dependence of the sum rules for the structure
functions of polarized $e(\mu)N$ scattering is discussed. The determination of
twist-4 corrections to the structure functions at high $Q^2$ by QCD sum rules
is reviewed and critically analyzed. It is found that in the case of the
Bjorken sum rule the twist-4 correction is small at $Q^2 > 5 GeV^2$ and does
not influence the value of $\alpha_s$ determined from this sum rule. However,
the accuracy of the today experimental data is insufficient to reliably
determine $\alpha_s$ from the Bjorken sum rule. For the singlet sum rule --
$p+n$ -- the QCD sum rule gives only the order of magnitude of twist-4
correction. At low and intermediate $Q^2$ the model is presented which realizes
a smooth connection of the Gerasimov-Drell-Hearn sum rules at $Q^2 = 0$ with
the sum rules for $\Gamma_{p,n}(Q^2)$ at high $Q^2$. The model is in a good
agreement with the experiment.


title:
Chiral Perturbation Theory and U(3)_L\times U(3)_R Chiral Theory of
  Mesons

abstract:
  We examine low energy limit of $U(3)_L\times U(3)_R$ chiral theory of mesons
through integrating out fields of vector and axial-vector mesons. The effective
lagrangian for pseudoscalar mesons at $O(p^4)$ has been obtained, and five low
energy coupling constants $L_i(i=1,2,3,9,10)$ have been revealed. They are in
good agreement with the results of CHPT's at $\mu \sim m_\rho$.


title: Power Corrections to Event Shapes in Deep Inelastic Scattering

abstract:
  We investigate the power-suppressed corrections to the mean values of various
quantities that characterise the shapes of final states in deep inelastic
lepton scattering. Our method is based on an analysis of one-loop Feynman
graphs containing a massive gluon, which is equivalent to the evaluation of
leading infrared renormalon contributions. As in $\ee$ annihilation, we find
that the leading corrections are proportional to $1/Q$. We give quantitative
estimates based on the hypothesis of a universal low-energy effective coupling.


title: Power Corrections to Event Shape Distributions

abstract:
  We estimate the effects of non-perturbative physics on the differential
distributions of infrared- and collinear-safe $e^+e^-$ event shape variables,
by extending the notion of an infrared-regular effective strong coupling, which
accounts for the non-perturbative corrections to the mean values of several
shape variables, to their distributions. This leads to $1/Q$ power corrections
over a range of values of the shape variables considered, where $Q$ is the
centre-of-mass energy. In the case of the thrust variable, the leading
correction is simply a shift of the distribution, by an amount proportional to
$1/Q$. We show that this gives an excellent description of the data throughout
a wide range of $T$ and $Q$.


title:
Radiative corrections to the lineshape of a heavy Higgs boson at muon
  colliders

abstract:
  We study the NNLO radiative corrections of enhanced electroweak strength to
the lineshape of the Higgs boson in the processes ($\mu^+\mu^- \to H \to ZZ$)
and ($\mu^+\mu^- \to H \to t\bar t$), which are of interest for Higgs searches
at a possible muon collider. We give the radiative corrections both in the
on-shell renormalization scheme and in the pole renormalization scheme. The
pole scheme appears to have better convergence properties, in agreement with
previous results regarding the position of the Higgs pole in the complex plane.


title: CP Violation in B Decays from Anomalous tbW Interactions

abstract:
  We calculate the effect of new CP violating interactions parameterized by an
anomalous $tbW$ coupling on CP-odd observables in B decays. We find that
couplings consistent with current bounds induce observable effects in some CP
asymmetries that will be measured in B-factories. The new effects are
sufficiently large that they can actually test specific models that give rise
to these $tbW$ interactions.


title: Theory of Light Quarks in the Confining Vacuum

abstract:
  The light quark propagation in the confining vacuum, described by an
(infinite) set of gauge-invariant vacuum correlators, is studied in detail. To
keep gauge invariance at each step the system of light quark and heavy
antiquark is considered, and the nonlinear equations are written explicitly for
the quark propagator in the limit of large $N_c$. For the lowest (Gaussian)
correlator the system is studied in various approximations, and the
relativistic WKB method is used to demonstrate the scalar confining interaction
of light quarks, which implies chiral symmetry breaking. The chiral condensate
is estimated by the relativistic WKB method, and connection to the density of
global zero modes is clarified. The higher even order correlators are shown to
yield the same properties of scalar confining interaction for light quarks. No
attempt was made to solve the obtained nonlinear equations numerically, but the
qualitative conclusion on connection between confinement and chiral symmetry
breaking is drawn, and an estimate of the chiral condensate is performed.


title: CP Violation and FCNC in the Third Family from Effective Supersymmetry

abstract:
  I discuss a ``more minimal'' modification of the minimal supersymmetric
standard model, in which supersymmetry breaking is connected with the physics
of flavor. Flavor Changing Neutral Currents (FCNC) for the first two families
are suppressed, and for the third family may be of comparable size to the FCNC
in the Standard Model.


title: Chaotic inflation with running nonminimal coupling

abstract:
  We have found a successful model of chaotic inflation with an inflaton
coupled nonminimally with gravity. The nonminimal coupling constant $\xi$ runs
with the evolution of the inflaton. The running nature of the coupling leads
naturally to the situations where the coupling becomes small enough to have
sufficient period of the inflation to resolve the cosmological puzzles.


title:
Exact formulae for Higgs production through e gamma --> e H in the
  non-linear R_\xi gauge

abstract:
  We study the production of the SM Higgs boson (H^0) at future e gamma
colliders, through the reaction e gamma --> e H^0. The amplitude is evaluated
using the non-linear R_\xi gauge, which greatly simplifies the calculation.
Complete analytical expressions for the amplitudes are presented, which include
the contributions from 1-loop triangles "gamma gamma^* H^0" and "gamma Z^* H^0"
as well as the W- and Z-boxes with their related $eeH^0$ triangle graphs. The
resulting cross section for this mechanism indicates that it could be used to
detect the Higgs signal and to test its properties.


title: Supersymmetric QCD flavor changing top quark decay

abstract:
  We present a detailed and complete calculation of the gluino and scalar
quarks contribution to the flavour-changing top quark decay into a charm quark
and a photon, gluon, or a Z boson within the minimal supersymmetric standard
model including flavour changing gluino-quarks-scalar quarks couplings in the
right-handed sector. We compare the results with the ones presented in an
earlier paper where we considered flavour changing couplings only in the
left-handed sector. We show that these new couplings have important
consequences leading to a large enhancement when the mixing of the scalar
partners of the left- and right-handed top quark is included. Furthermore CP
violation in the flavour changing top quark decay will occur when a SUSY phase
is taken into account.


title:
Doubly charged Higgsino contribution to the decays mu-->e photon and
  mu-->3e and to the anomalous magnetic moment of the muon within the
  left-right supersymmetric model

abstract:
  We present a detailed and complete calculation of the doubly charged Higgsino
contribution to the decays mu--> e photon and mu--> 3e and to the anomalous
magnetic moment of the muon within the left-right supersymmetric model. We
include the mixing of the scalar partners of the left and right handed leptons,
and show that it leads to a strong enhancement of the decay modes in certain
scenarios. We find that the contribution of the doubly charged Higgsino can be
close to the known experimental values and are reachable by future experiments.


title:
Sparticle Spectroscopy and Phenomenology in a New Class of Gauge
  Mediated Supersymmetry Breaking Models

abstract:
  Recently, a proposal (by R.N.M. and S.N.) was made for a new class of gauge
mediated supersymmetry breaking (GMSB) models where the standard model gauge
group is embedded into the gauge group $SU(2)_L\times U(1)_{I_{3R}}\times
U(1)_{B-L}$ (or $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$) at the supersymmetry
breaking scale $\Lambda$. Supersymmetry breaking is transmitted to the visible
sector via the same fields that are responsible for gauge symmetry breaking
rather than by vector-like quarks and leptons as in the conventional GMSB
models. These models have a number of attractive properties such as exact
R-parity conservation, non-vanishing neutrino masses and a solution to the
SUSYCP (and strong CP) problem. In this paper, we present the detailed
sparticle spectroscopy and phenomenological implications of the various models
of this class that embody the general spirit of our previous work but use a
larger variety of messenger fields. A distinct characteristic of this class of
models is that unlike the conventional GMSB ones, the lightest neutralino is
always the NLSP leading to photonic events in the colliders.


title:
Reduction of One-loop Tensor Form-Factors to Scalar Integrals: A General
  Scheme

abstract:
  A general method for reducing tensor form factors, that appear in one-loop
calculations in dimensional regularization, to scalar integrals is presented.
The method is an extension of the reduction scheme introduced by Passarino and
Veltman and is applicable in all regions of parameter space including those
where kinematic Gram determinant vanishes. New relations between the the form
factors that valid for vanishing Gram determinant play a key role in the
extended scheme.


title: Dark Matter and Cosmic Rays from Light Gauginos

abstract:
  An attractive class of SUSY-breaking mechanisms predicts a photino mass of
order 1 GeV. Relic photinos can naturally account for the observed dark matter.
Detection of these light photinos is discussed and contrasted with conventional
WIMPs. In this scenario the gluino mass is about 100 MeV. The lightest
gluino-containing baryon could account for the recently observed ultra-high
energy cosmic rays, which violate the GZK bound.


title: SUSY Breaking and Light Gauginos

abstract:
  Several supersymmetry breaking mechanisms do not produce dimension-3
operators. I show here that this scenario is consistent with present
observations and has several significant virtues: i) When there are no
dimension-3 SUSY-breaking operators there is no SUSY-CP problem. ii)
SUSY-breaking need not occur through gauge singlets, so that the cosmological
problems often encountered in hidden sector SUSY-breaking can be avoided. iii)
Photino and gluino and $R$-hadron masses are naturally consistent with relic
photinos providing the required dark matter density.
  Requiring spontaneous electroweak symmetry implies that scalar masses are
mostly in the $\sim 100$ GeV range. The gluino and photino are massless at tree
level. At 1-loop, the gluino and photino masses at the ew scale are predicted
to be $m_{\gluino}\sim 10 - 600$ MeV and $m_{\photino} \sim 100 - 1400$ MeV.
New hadrons with mass $\sim 1 \frac{1}{2}$ GeV are predicted and described. The
``extra'' flavor singlet pseudoscalar in the $\iota(1440)$ region which has
been observed in several experiments is naturally interpreted as the
mainly-$\gluino \gluino$ bound state which gets its mass via the QCD anomaly.
Its superpartner, a gluon-gluino bound state, would be the lightest $R$-hadron.
For the most interesting portions of parameter space the $R^0$ lifetime is
$10^{-6} - 10^{-10}$ sec, so existing searches would not have been sensitive to
it. Search strategies and other consequences of the scenario are briefly
mentioned.


title: Neutrinos Must be Tachyons

abstract:
  The negative mass squared problem of the recent neutrino experiments from the
five major institutions prompts us to speculate that, after all, neutrinos may
be tachyons. There are number of reasons to believe that this could be the
case. Stationary neutrinos have not been detected. There is no evidence of
right handed neutrinos which are most likely to be observed if neutrinos can be
stationary. They have the unusual property of the mass oscillation between
flavors which has not been observed in the electron families. While Standard
Model predicts the mass of neutrinos to be zero, the observed spectrum of
Tritium decay experiments hasn't conclusively proved that the mass of neutrino
is exactly zero. Based upon these observations and other related phenomena, we
wish to argue that there are too many inconsistencies to fit neutrinos into the
category of ordinary inside light cone particles and that the simplest possible
way to resolve the mystery of the neutrino is to change our point of view and
determine that neutrinos are actually tachyons.


title: CP Violation in the Top-Quark Pair Production at a Next Linear Collider

abstract:
  We provide a detailed, model-independent, study for CP violation effects due
to the T-odd top-quark electric dipole moment (EDM) and weak dipole moment
(WDM) in the top-quark pair production via $e^+e^-$ and two-photon annihilation
at a next $e^+e^-$ linear collider (NLC). There are two methods in detecting CP
violation effects in these processes. One method makes use of measurements of
various spin correlations in the final decay products of the produced top-quark
pair, while the other is to measure various CP-odd polarization asymmetry
effects of the initial states. In the $e^+e^-$ case only the first method can
be used, and in the $\gamma\gamma$ case both methods can be employed. We
provide a complete classification of angular correlations of the $t$ and
$\bar{t}$ decay products under CP and CP\tilde{T} which greatly faciliate CP
tests in the $e^+e^-$ mode. Concentrating on the second method with the Compton
back-scattered high-energetic laser light off the electron or positron beam in
the two-photon mode, we construct two CP-odd and CP\tilde{T}-even initial
polarization configurations and apply them to investigating CP-violating
effects due to the top-quark EDM. With a typical set of experimental parameters
at the NLC, we compare the 1-\sigma sensitivities to the top-quark EDM and WDM
in the $e^+e^-$ mode and the two-photon mode. Some model expectation values of
the T-odd parameters are compared with the results.


title: A Monte Carlo for POLarized (semi-inclusive) Deep Inelastic Scattering

abstract:
  POLDIS is a Monte Carlo program for polarized (semi-inclusive) deep inelastic
scattering (DIS). Unpolarized DIS events are generated with the existing
lepto-production event generators LEPTO for DIS and AROMA for Heavy Flavor
production. The relevant spin asymmetries are computed at partonic level to
first order in alpha_s for each generated event, and are then convoluted with
the corresponding ratio between the polarized and unpolarized parton
distribution functions (i.e. parton polarization). This procedure provides a
polarization weight for each event. The average of these polarization weights
gives the polarized cross section spin-asymmetry for the generated sample. The
code consists of a set of subroutines to be linked with LEPTO and/or AROMA.


title:
Cosmic Ray Constraints On the Annihilation of Heavy Stable Neutrinos in
  the Galactic Halo

abstract:
  We carry out a detailed analysis of fluxes of cosmic ray antiprotons,
positrons, electrons and photons to be expected from the annihilation of relic
heavy neutrinos in the galactic halo. The spectra of particles are evaluated by
Monte Carlo simulation. The results of calculations show that the investigation
of cosmic ray positron spectra at high energies could provide a distinctive
signal for annihilation of very heavy neutrinos in the Galaxy and give an
important information on parameters of dark matter particles.


title: Neutrino Masses in Astrophysics and Cosmology

abstract:
  Astrophysical and cosmological arguments and observations give us the most
restrictive constraints on neutrino masses, electromagnetic couplings, and
other properties. Conversely, massive neutrinos would contribute to the cosmic
dark-matter density and would play an important role for the formation of
structure in the universe. Neutrino oscillations may well solve the solar
neutrino problem, and can have a significant impact on supernova physics.


title: Fermion-Boson-Type Subquark Model and F2-Changing Phenomena

abstract:
  The mass differences in all neutral pseudo scalar mesons and CP violations
associated with the mixings are investigated in the context of the fermion-
boson-type subquark model. These phenomena are unifyingly explained by the
neutral scalar subquark exchanges between two quarks inside the present meson.
It is predicted that the mass differences and CP violations of D, B and T meson
systems.


title: Constraints on the Universal Contact Interaction

abstract:
  Forces beyond those of the standard model may manifest themselves at low
energies as four-fermion contact interactions. If these new forces are
independent of colour and flavour quantum numbers including baryon and lepton
number, then all low energy constraints, arising from quark-lepton
universality, flavour-changing neutral currents and atomic parity violation are
evaded. This is due to the global U(45) symmetry which the standard model
exhibits in the limit of vanishing gauge and Yukawa couplings. The
corresponding contact interaction is a unique current-current interaction.
Constraints from LEP2 imply that this universal contact interaction cannot be
the origin of the recently observed high-$Q^2$ events at HERA.


title:
Comparative Analysis of Multiplicity Distributions in Inelastic
  Processes for Different Colliding Particles and Nuclei

abstract:
  Theoretical prediction of oscillations of cumulant moments of parton
multiplicity distributions inside a jet supported by experimental data in some
multiple production processes asks for analysis of the phenomenon for the whole
set of available reactions. We have found out that the oscillations persist in
any kind of processes and increase for particles with more complicated
structure i.e. in the order of ee, eh, hh, hA, AA. The effect is not strongly
dependent on the available phase space. Theoretical values of moments for quark
and gluon jets up to 5th rank are shown. Zeros of the truncated generating
function and singularities of the total generating function are discussed.


title: Low and High Energy Limits of Particle Spectra in QCD Jets

abstract:
  Charged particle energy spectra in e+e- annihilation are compared with the
analytical predictions from the QCD evolution equation in the Modified Leading
Log Approximation. With the nonperturbative initial condition shifted down to
threshold as suggested by the Local Parton Hadron Duality picture a good
description of the data from the lowest up to highest available energies
results. The two essential parameters in this approach are determined from a
moment analysis. The sensitivity of the fit to the running of alpha_s and to
the number of active flavours (including a light gluino) is demonstrated. For
very high energies the theory predicts a scaling behaviour in certain rescaled
variables (``zeta-scaling''). The data show an approximate behaviour of this
type in the present energy range and come close to the predicted asymptotic
scaling function for the small particle energies.


title: Proton spin structure in the rest frame

abstract:
  It is shown that the quark-parton model in the standard infinite momentum
approach overestimate the proton spin structure function $g_1(x)$ in comparison
with the approach taking consistently into account the internal motion of
quarks described by a spherical phase space in the proton rest frame.
Particularly, it is shown the first moment of the spin structure function in
the latter approach, assuming only the valence quarks contribution to the
proton spin, does not contradict to the experimental data.


title: Top Priorities: Questions for Snowmass '96

abstract:
  Questions on the top quark posed for the 1996 DPF/DPB Summer Study on New
Directions for High-Energy Physics (Snowmass 96).


title: Pair production of scalar leptoquarks at the Tevatron

abstract:
  We present the cross section for pair production of scalar leptoquarks $LQ$
in $p\bar{p}$ collisions, $p+\bar{p} \to LQ + \bar{LQ} + X$, at the Fermilab
Tevatron in next-to-leading order QCD. Including the higher-order corrections
stabilizes the theoretical prediction and increases the size of the cross
section for renormalization/factorization scales close to the mass of the
leptoquarks. This leads to an increase of the lower bound on the mass of scalar
leptoquarks by up to 15 GeV with respect to earlier analyses.


title:
Rare B -> K^* l^+ l^- decay, two Higgs doublet model, and light cone QCD
  sum rules

abstract:
  The decay width, forward-backward asymmetry and lepton longitudinal and
transversal polarization for the exclusive K^* -> l^+ l^- decay in a two Higgs
doublet model are computed. It is shown that all these quantities are very
effective tools for establishing new physics.


title: Photoproduction of jets at HERA in next-to-leading order QCD

abstract:
  A new next-to-leading order Monte Carlo program for the calculation of jet
cross sections in photoproduction is described. The contributions from both
resolved and direct components are included to O(\alpha \alpha_s^2). Properties
of the predictions for various inclusive jet and dijet observables are
discussed and comparisons with HERA data are presented.


title:
Perturbative O(alpha_s^2) Corrections to the Hadronic Cross Section Near
  Heavy Quark-Antiquark Thresholds in e+e- Annihilation

abstract:
  It is demonstrated how perturbative O(alpha_s^2) relativistic corrections to
the non-relativistic stable heavy quark-antiquark production cross section in
e^+e^- annihilation based on a Coulombic QCD potential can be systematically
calculated using the concept of effective field theories. The O(alpha_s^2)
corrections from the relativistic energy-momentum relation, the relativistic
phase space corrections and the O(alpha_s^2) corrections involving the group
theoretical factors C_F^2 and C_F T are determined explicitly. For the case of
$t\bar t$ production the sum of these corrections amounts to 3% - 7% over the
whole threshold regime and is insensitive to variations in the top width.
Perturbative O(alpha_s^2) corrections to the leptonic decay width of heavy
quark-antiquark $^3S_1$ vector resonances are extracted.


title: Dipole Moments of the Rho Meson

abstract:
  The electric and magnetic dipole moments of the rho meson are calculated
using the propagators and vertices derived from the QCD Dyson-Schwinger
equations. Results obtained from using the Bethe-Salpeter amplitude studied by
Chappell, Mitchell and Tandy, and Pichowsky and Lee, are compared. The rho
meson EDM is generated through the inclusion of a quark electric dipole moment,
which is left as a free variable. These results are compared to the
perturbative results to obtain a measure of the effects of quark interactions
and confinement. The two dipole moments are also calculated using the
phenomenological MIT bag model to provide a further basis for comparison.


title:
Has the Substructure of Quarks and Leptons Been Found also by the H1 and
  ZEUS Detectors at HERA?

abstract:
  The significant excess of events recently found by the H1 and ZEUS
Collaborations at HERA in the deep-inelastic e^+ p scattering for high
momentum-transfers squared Q^2>15000 GeV^2 over the expectation of the standard
model can be explained by either one of the following possible consequences of
the substructure of quarks and leptons: 1) production of leptoquarks (Phi), 2)
exchange of an excited Z boson (Z'), 3) intrinsic form factors of quarks (or
leptons), 4) intrinsic anomalous magnetic moments of quarks, 5) production of
excited quarks (q^*), and 6) that of excited positrons (e^*+). The masses of
these new particles are estimated to be m(Phi) = 280-440 GeV, m(Z') = 210-250
GeV, m(q^*) = 120-140 GeV, and m(e^*+) = 300-370 GeV, although the
possibilities 2) and 5) are excluded by the currently available experimental
constraints.


title:
Color Anomaly and Flavor-Singlet Axial Charge of the Proton in the
  Chiral Bag: The Cheshire Cat Revisited

abstract:
  Quantum effects inside the chiral bag induce a color anomaly which requires a
compensating surface term to prevent breakdown of color gauge invariance. We
show that the presence of this surface term first discovered several years ago
allows one to derive in a gauge-invariant way a chiral-bag version of the
Shore-Veneziano two-component formula for the flavor-singlet axial charge of
the proton. This has relevance to what is referred to as the ``proton spin
problem" on the one hand and to the Cheshire-Cat phenomenon in hadron structure
on the other. We show that when calculated to the leading order in the color
gauge coupling and for a specific color electric monopole configuration in the
bag, one can obtain a striking Cheshire-Cat phenomenon with a negligibly small
singlet axial charge.


title:
Mass hierarchy from compositeness hierarchy in supersymmetric gauge
  theory

abstract:
  The possibility that the mass hierarchy is intimately associated with the
compositeness level of the matters is proposed in supersymmetric gauge theory.
This implies, for instance, that the preons constituting top quark consists of
the ``prepreons'' binded by the same gauge force making the charm quark out of
another preons. The exemplifying toy model illustrates how the hierarchy in the
yukawa coupling constants in the up-quark sector is generated from the
underlying gauge dynamics. It is also indicated that the incorporation of
down-type quarks as elementary objects leads to unpleasant results generically.
Thus all the quarks as well as the leptons must also be regarded as composite
in the present approach.


title:
Exact solutions and triviality of lambda (phi^*phi)^2 theory in the
  Feshbach-Villars formulation

abstract:
  The complex scalar quantum field theory with a lambda (phi^*phi)^2
interaction is considered in the Feshbach-Villars formulation. It is shown that
exact few-particle eigenstates of the QFT Hamiltonian can be obtained. The
resulting relativistic few-body equations correspond to Klein-Gordon particles
interacting via delta-function, or ``contact'', potentials. Momentum-space
solutions of the two-body equation yield a `trivial' unity S-matrix.


title: New Developments in Precision Electroweak Physics

abstract:
  Our picture of the electroweak interactions continues to improve, with ever
more precise constraints on the masses of the Higgs boson(s) and on
non-standard physics. Some recent developments include: (a) a calculation of
higher-order effects on the weak mixing angle which reduces scheme-dependence,
(b) a long-awaited improvement in the experimental accuracy of measurement of
parity violation in atomic cesium, and (c) improvements in top quark and $W$
mass measurements from Fermilab and $W$ mass measurements from LEP.


title: Top-ology

abstract:
  Extended version of an article on top-quark physics, to appear in the May
1997 issue of Physics Today.


title:
Analytic Model for the QCD Running Coupling with Universal
  $\bar{\alpha}_s(0)$ Value

abstract:
  We discuss the new model expression $\bar{\alpha}_{an}(Q^2)$ recently
obtained for the QCD running coupling with a regular ghost-free behavior in the
"low $Q^2$" region. Being deduced from the standard "asymptotic-freedom"
expression by imposing the $Q^2$-analyticity -- without any adjustable
parameters -- it obeys nice features: (i) The universal limiting value
$\bar{\alpha}_{an}(0)=4\pi /\beta_0 \simeq 1.4$ expressed only via group
symmetry factors and independent of experimental estimates on the running
coupling $\bar{\alpha}_s(Q^2)$ (of QCD scale parameter $\Lambda$). This value
turns out to be stable with respect to higher order corrections; (ii) Stability
of IR behavior with respect to higher-loop effects; (iii) Coherence between the
experimental $\bar{\alpha}_{an}(M_{\tau}^2)$ value and integral information on
IR $\bar{\alpha}_s(Q^2)$ behavior as extracted from jet physics data.


title:
Magnetic field generation in first order phase transition bubble
  collisions

abstract:
  We consider the formation of a ring-like magnetic field in collisions of
bubbles of broken phase in an abelian Higgs model. Particular attention is paid
on multiple collisions. The small collision velocity limit, appropriate to the
electroweak phase transition, is discussed. We argue that after the completion
of the electroweak phase transition, when averaged over nucleation center
distances, there exists a mean magnetic field $B\simeq 2.0\times 10^{20}$ G
with a coherence length $9.1 \times 10^3 GeV^{-1}$ (for m_H=68 GeV). Because of
the ring-like nature of B, the volume average behaves as $B \sim 1/L$. Taking
into account the turbulent enhancement of the field by inverse cascade, we
estimate that colliding electroweak bubbles would give rise to a mean field
$B_{rms}\simeq 10^{-21}$ G at 10 Mpc comoving scale today.


title: Modelling quark distribution and fragmentation functions

abstract:
  The representation of quark distribution and fragmentation functions in terms
of non-local operators is combined with a simple spectator model. This allows
us to estimate these functions for the nucleon and the pion ensuring correct
crossing and support properties. We give estimates for the unpolarized
functions as well as for the polarized ones and for subleading (higher twist)
functions. Furthermore we can study several relations that are consequences of
Lorentz invariance and of C, P, and T invariance of the strong interactions.


title: Leptoquarks in SUSY Unified Models and the HERA Events

abstract:
  Motivated by the recent HERA events which are consistent with a possible
leptoquark interpretation, we discuss the prospects for including additional
light colour triplets and anti-triplets in the spectrum of supersymmetric
unified theories. We focus on a particular string-inspired Pati-Salam model,
and propose a simple mechanism by which a light colour triplet of charge -1/3
plus anti-triplet of charge 1/3, may have a mass of order 200 GeV, with one of
the new states having leptoquark couplings and with proton decay suppressed. We
also discuss possible scenarios for gauge unification in such a model.


title: Searching For Anomalous $\tau \nu W$ Couplings

abstract:
  The capability of current and future measurements at low and high energy
$e^+e^-$ colliders to probe for the existence of anomalous, CP conserving,
$\tau \nu W$ dipole moment-type couplings is examined. At present, constraints
on the universality of the tau charged and neutral current interactions as well
as the shape of the $\tau \to \ell$ energy spectrum provide the strongest
bounds on such anomalous couplings. The presence of these dipole moments are
shown to influence, e.g., the extraction of $\alpha_s(m_\tau^2)$ from $\tau$
decays and can lead to apparent violations of CVC expectations.


title: Hera Events, Tevatron Jets, and the Uncertainty On Quarks At Large X

abstract:
  The recently reported excess of events at HERA compared to QCD calculations
impels us to examine all possible Standard Model explanations before invoking
``new physics''. We explore the possibility of adding an unusual, but small,
component of additional quarks at large x (beyond x>0.75) as a way to increase
the predicted SM cross-section in the HERA kinematic region by the QCD
evolution feed-down effect. We describe various scenarios under which this can
be achieved while maintaining good global fits to all established data sets.
This implies a much larger SM uncertainty than commonly assumed. In addition,
the modified parton distributions provide another possible mechanism to account
for the CDF high-pt jet excess which occurs at similar x and Q^2 values.


title: R-Parity Violation and Unification

abstract:
  The reported anomaly in deep-inelastic scattering at HERA has revived
interest in the phenomenology of R-parity violation. From the theoretical point
of view, the existence of R-violating interactions poses two considerable
problems. The first one concerns the flavour structure of the interactions and
the origin of an appropriate suppression of flavour-changing neutral-current
processes and lepton-family transitions. The second one concerns the way of
embedding R-violating interactions in a grand unified theory (GUT) without
introducing unacceptable nucleon decay rates. We show that the second problem
can be solved by a mechanism which is purely group theoretical and does not
rely on details of the flavour theory. We construct explicit GUT models in
which our mechanism can be realized.


title: Inter-meson Potentials in Dual Ginzburg-Landau Theory

abstract:
  We calculate inter-meson potentials numerically by solving classical
equations of motion derived from Dual Ginzburg-Landau (DGL) Theory. Inter-meson
potentials in DGL theory are shown to be similar to those of the string-flip
model and well reproduce behaviors of the short-range interaction at the
classical level. We also compare our results with those from lattice QCD Monte
carlo calculations.


title: Compositeness Condition in the Nambu-Jona-Lasinio Model

abstract:
  The Nambu-Jona-Lasinio model is the special case of the renormalized Yukawa
model with the compositeness condition. We use it to calculate the effective
coupling constants in terms of the compositeness sale (momentum cut off) at the
next-to-leading order in 1/N. The next-to-leading correction is too large in
the model of scalar composite, while that in the induced gauge theory is
reasonably suppressed due to the gauge cancellation of the leading divergences.


title: Dual Shapiro-Virasoro amplitudes in the QCD dipole picture

abstract:
  Using the QCD dipole picture of BFKL dynamics and the conformal invariance
properties of the BFKL kernel in transverse coordinate space, we show that the
1--to--p dipole densities can be expressed in terms of dual Shapiro- Virasoro
amplitudes B{2p+2} and their generalization including non-zero conformal spins.
We discuss the possibility of an effective closed string theory of interacting
QCD dipoles.


title:
Could we learn more about HERA high Q^2 anomaly from LEP200 and TEVATRON
  ?

abstract:
  The excess of high Q^2 events at HERA has been the subject of recent
extensive studies in the framework of several models related to new physics.
Here, we would like to concentrate on the most promising, from our point of
view, model describing HERA anomaly. We investigate HERA events within the
R-parity broken SUSY model and check its relation to LEP and TEVATRON
colliders. This study shows that if a squark resonance really takes place at
HERA, supersymmetry with broken R-parity can be revealed at either LEP200 or
TEVATRON.


title: Direct Estimation of Sizes of Higher-Order Graphs

abstract:
  With the aid of simple examples we show how to make simple estimates of the
sizes of higher-order Feynman graphs. Our methods enable appropriate values of
renormalization and factorization scales to be made. They allow the diagnosis
of the source of unusually large corrections that are in need of resummation.


title: The Linear Meson Model and Chiral Perturbation Theory

abstract:
  We compare the linear meson model and chiral perturbation theory in next to
leading order in the quark mass expansion. In particular, we compute the
couplings L_4--L_8 of chiral perturbation theory as functions of the parameters
of the linear model. They are induced by the exchange of 0^{++} scalar mesons.
We use a phenomenological analysis of the effective vertices of the linear
model in terms of pseudoscalar meson masses and decay constants. Our results
for the L_i agree with previous phenomenological estimates.


title: Coherent Neutrino Interactions in a Dense Medium

abstract:
  Motivated by the effect of matter on neutrino oscillations (the MSW effect)
we study in more detail the propagation of neutrinos in a dense medium. The
dispersion relation for massive neutrinos in a medium is known to have a
minimum at nonzero momentum p \sim (G_F\rho)/\sqrt{2}. We study in detail the
origin and consequences of this dispersion relation for both Dirac and Majorana
neutrinos both in a toy model with only neutral currents and a single neutrino
flavour and in a realistic "Standard Model" with two neutrino flavours. We find
that for a range of neutrino momenta near the minimum of the dispersion
relation, Dirac neutrinos are trapped by their coherent interactions with the
medium. This effect does not lead to the trapping of Majorana neutrinos.


title: Electroweak Baryogenesis and Higgs Physics

abstract:
  Electroweak Baryogenesis is a particularly attractive theoretical scenario,
since it relies on physics which can be tested at present high energy collider
facilities. Within the Standard Model, it has been shown that the requirement
of preserving the baryon number generated at the weak scale leads to strong
bounds on the Higgs mass, which are already inconsistent with the present
experimental limits. In the Minimal Supersymmetric extension of the Standard
Model we demonstrate that light stop effects can render the electroweak phase
transition sufficiently strongly first order, opening the possibility of
electroweak baryogenesis for values of the Higgs mass at the LEP2 reach. The
generation of the observed baryon asymmetry also requires small chargino masses
and new CP-violating phases associated with the stop and Higgsino mass
parameters. We discuss the direct experimental tests of this scenario and other
relevant phenomenological issues related to it.


title: Looking for Exotic Multiquark States in Nonleptonic B Decays

abstract:
  Recent data on inclusive B decays into charmonium states taken by the CLEO
collaboration suggest that a sizeable fraction of the nonleptonic decays may
consist of the $J/\psi \Lambda \overline p$ three body final state,
corresponding to a distinct enhancement in the inclusive $J/\psi$ momentum
distribution. The kinematical boundary of this structure corresponds to the
case where the $J/\psi$ recoils nearly monoenergetically in the B rest system
against a partner having mass of $\simeq$ 2 GeV. This may allow the observation
of a $\Lambda-\overline p $ bound state near or just below threshold; i.e.,
strange baryonium, even if the production rate is small.
  Using a phase space approach to the B meson decay, we study the $J/\psi$
momentum distribution and the effect of baryonium formation. We also discuss
the possible observation of pentaquarks and hadronically-bound $J/\psi$ by the
observation of monoenergetic baryons in these decays.


title: A Simplified Summary of Supersymmetry

abstract:
  I give an overview of the motivations for and theory/phenomenology of
supersymmetry.


title: Next-To-Leading Logarithmic Results in $ B \to X_s \gamma $

abstract:
  We give a brief review of the next-to-leading logarithmic results in $B \to
X_s \gamma$. Combining the results of different groups, a practically complete
next-to-leading-logarithmic prediction of the inclusive decay rate was recently
presented. The theoretical uncertainty in the decay rate in now less than half
of the error in the previously leading-logarithmic result. Therefore, the
inclusive $B \to X_s \gamma$ mode will provide important tests of the SM and
its extensions when more precise experimental data is available.


title: On the role of power expansions in quantum field theory

abstract:
  Methods of summation of power series relevant to applications in quantum
theory are reviewed, with particular attention to expansions in powers of the
coupling constant and in inverse powers of an energy variable. Alternatives to
the Borel summation method are considered and their relevance to different
physical situations is discussed. Emphasis is placed on quantum chromodynamics.
Applications of the renormalon language to perturbation expansions (resummation
of bubble chains) in various QCD processes are reported and the importance of
observing the full renormalization-group invariance in predicting observables
is emphasized. News in applications of the Borel-plane formalism to
phenomenology are conveyed. The properties of the operator-product expansion
along different rays in the complex plane are examined and the problem is
studied how the remainder after subtraction of the first $n$ terms depends on
the distance from euclidean region. Estimates of the remainder are obtained and
their strong dependence on the nature of the discontinuity along the cut is
shown. Relevance of this subject to calculations of various QCD effects is
discussed.


title: Comment on "Cherenkov Radiation by Neutrinos in a Supernova Core"

abstract:
  Mohanty and Samal have shown that the magnetic-moment interaction with
nucleons contributes significantly to the photon dispersion relation in a
supernova core, and with an opposite sign relative to the usual plasma effect.
Because of a numerical error they overestimated the magnetic-moment term by two
orders of magnitude, but it is still of the same order as the plasma effect. It
appears that the Cherenkov processes gamma+nu -> nu and nu -> nu+gamma remain
forbidden, but a final verdict depends on a more detailed investigation of the
dynamical magnetic susceptibility of a hot nuclear medium.


title:
Calculation of Infrared-Divergent Feynman Diagrams with Zero Mass
  Threshold

abstract:
  Two-loop vertex Feynman diagrams with infrared and collinear divergences are
investigated by two independent methods. On the one hand, a method of
calculating Feynman diagrams from their small momentum expansion extended to
diagrams with zero mass thresholds is applied. On the other hand, a numerical
method based on a two-fold integral representation is used. The application of
the latter method is possible by using lightcone coordinates in the parallel
space. The numerical data obtained with the two methods are in impressive
agreement.


title:
Results on K --> 2pi decays at O(p^6) and epsilon'/epsilon from an
  effective chiral lagrangian approach

abstract:
  We have combined a new systematic calculation of mesonic matrix elements at
O(p^6) from an effective chiral lagrangian approach using Wilson coefficients
taken from [G.Buchalla, A.J.Buras, M.E.Lautenbacher, Rev.Mod.Phys. 68 (1996)
1125], derived in the framework of perturbative QCD, and restricted partly by
experimental data.
  We derive complete expressions for K --> 2pi amplitudes and give new
estimates for epsilon'/epsilon.


title:
Neutron Electric Dipole Moment In The Standard Model: Valence Quark
  Contributions

abstract:
  We present a complete three-loop calculation of the electric dipole moment of
the $u$ and $d$ quarks in the Standard Model. For the $d$ quark, more relevant
for the experimentally important neutron electric dipole moment, we find
cancellations which lead to an order of magnitude suppression compared with
previous estimates.


title: Calculation of gamma plus pion to two pions

abstract:
  The problem of $\gamma \pi \to \pi \pi$ is studied using the axial anomaly,
elastic unitarity, analyticity and crossing symmetry. The solution of the
integral equation for this amplitude is given by an iteration procedure.The
final solution disagrees with vector meson dominance models.


title: B to eta' + X and The QCD Anomaly

abstract:
  Mechanisms for the observed large $Br(B \to \eta' +X_s)$ are examined. We
propose that the dominant fraction of the $B \to \eta' +X_s$ rate is due mainly
to $b \to s g^*$, where $g^*$ is an off-shell gluon, followed by $g^* \to
g\eta'$ via the anomalous coupling of the $\eta'$ to two gluons. The calculated
rate for $B \to \eta'+X_s$ is in rough accord with experiment using a fairly
constant glue-glue-$\eta'$ form factor. This behavior of the form factor may be
indicative of glueball dominance of the channel. Searches via the modes $\eta'
h^+h^-$ ($h=\pi$ or $K$) may be worthwhile. Charmonia contributions [i.e $B \to
\eta_c, \psi (\to \eta'+X) +X_s$] can only account for at most 20% of the
central value of the signal. Implications for $B \to \eta' +X_d$ and for the
corresponding $\eta$ modes are also given.


title: Generalization of the Bound State Model

abstract:
  In the bound state approach the heavy baryons are constructed by binding,
with any orbital angular momentum, the heavy meson multiplet to the nucleon
considered as a soliton in an effective meson theory. We point out that this
picture misses an entire family of states, labeled by a different angular
momentum quantum number, which are expected to exist according to the geometry
of the three-body constituent quark model (for N_C=3). To solve this problem we
propose that the bound state model be generalized to include orbitally excited
heavy mesons bound to the nucleon. In this approach the missing angular
momentum is ``locked-up'' in the excited heavy mesons. In the simplest
dynamical realization of the picture we give conditions on a set of coupling
constants for the binding of the missing heavy baryons of arbitrary spin. The
simplifications made include working in the large M limit, neglecting nucleon
recoil corrections, neglecting mass differences among different heavy spin
multiplets and also neglecting the effects of light vector mesons.


title: CP Violating Bubble Wall and Electroweak Baryogenesis

abstract:
  The electroweak baryogenesis depends on the profile of the CP-violating
bubble wall created at the first order phase transition. We attempt to
determine it by solving the coupled equations of motion for the moduli and
phases of the two Higgs doublets at the transition temperature. A variety of
CP-violating bubble walls are classified by boundary conditions. We point out
that a sufficiently small explicit CP violation gives nonperturbative effects
to yield the baryon asymmetry of the universe.


title: Thermal charm production by massive gluons and quarks

abstract:
  We investigate charm production in an equilibrated quark-gluon plasma
produced in heavy-ion collisions at RHIC and LHC. Effective quark and gluon
masses are introduced from thermal QCD calculations. Assuming a Bjorken-type
longitudinal expansion and including the influence of temperature dependent
masses on the expansion, we determine the total number of c\bar{c} pairs
produced in the quark-gluon plasma phase. We calculate the charm production
rate at leading order with massive gluons and quarks and compare our result to
charm production by massless partons. We consider two different scenarios for
the initial conditions, a parton gas with a rather long kinetic equilibration
time and a minijet gas with a short equilibration time. In a parton gas,
assuming m_c=1.2 GeV, we obtain a substantial enhancement over the thermal
charm rate from massless quarks and gluons, up to 4.9 secondary charm quark
pairs in Au+Au collisions at RHIC and 245 charm pairs in Pb+Pb collisions at
the LHC.


title: Neutralino Relic Density including Coannihilations

abstract:
  We evaluate the relic density of the lightest neutralino, the lightest
supersymmetric particle, in the Minimal Supersymmetric extension of the
Standard Model (MSSM). For the first time, we include all coannihilation
processes between neutralinos and charginos for any neutralino mass and
composition. We use the most sophisticated routines for integrating the cross
sections and the Boltzmann equation. We properly treat (sub)threshold and
resonant annihilations. We also include one-loop corrections to neutralino
masses. We find that coannihilation processes are important not only for light
higgsino-like neutralinos, as pointed out before, but also for heavy higgsinos
and for mixed and gaugino-like neutralinos. Indeed, coannihilations should be
included whenever $|\mu| \lsim 2 |M_1|$, independently of the neutralino
composition. When $|\mu| \sim |M_1|$, coannihilations can increase or decrease
the relic density in and out of the cosmologically interesting region. We find
that there is still a window of light higgsino-like neutralinos that are viable
dark matter candidates and that coannihilations shift the cosmological upper
bound on the neutralino mass from 3 to 7 TeV.


title: Phenomenologically Viable Dynamical Electro-Weak Symmetry Breaking

abstract:
  The lack of deviations from the Standard Model at the current level of
experimental precision can be explained systematically in suitable models of
dynamical electro-weak symmetry breaking. The key ingredient is dynamics which
produces a scalar unitarity partner for the Goldstone-Bosons and which leads to
a decoupling of effects beyond the Standard Model. A phenomenologically
successful left-right symmetric model is presented from this point of view.


title: Exotic leptoquarks from superstring derived models

abstract:
  The H1 and ZEUS collaborations have recently reported a significant excess of
events at high $Q^2$ in positron-proton collisions. While there exists
insufficient data to conclusively determine the origin of this excess, one
possibility is that it is due to a new leptoquark at mass scale around 200 GeV.
We examine the type of leptoquark states that exist in superstring derived
standard-like models, and show that, while these models may contain the
standard leptoquark states which exist in Grand Unified Theories, they also
generically contain new and exotic leptoquark states with fractional lepton
number, $\pm1/2$. In contrast to the traditional GUT-type leptoquark states,
the couplings of the exotic leptoquarks to the Standard Model states are
generated after the breaking of $U(1)_{B-L}$. This important feature of the
exotic leptoquark states may result in local discrete symmetries which forbid
some of the undesired leptoquark couplings. We examine these couplings in
several models and study the phenomenological implications. The flavor
symmetries of the superstring models are found to naturally suppress leptoquark
flavor changing processes.