title: Anomalous $Z'$ effects in the WW channel at $LC 2000$

abstract:
  We consider the virtual signals of a $Z'$ of very general type in the process
$e^+e^-\to W^+W^-$ at a future linear $e^+e^-$ collider of 2000 GeV c.m. energy
($LC2000$). We show that possible deviations from the SM predictions in this
channel are related to similar deviations in the purely leptonic one in a way
that is only characteristic of this $Z'$ model, and not in general of possible
competitor models with anomalous gauge couplings.


title: Charmonium Production at the LHC

abstract:
  The analyses of large transverse momentum charmonium production at the
Tevatron have shown that fragmentation of gluons is an important production
mechanism. We study large-$p_T$ charmonium production in $pp$ collisions at the
LHC, and find that due to the copious gluon production at this energy, the
gluon fragmentation contribution completely overwhelms the fusion contribution
and the charm quark fragmentation contribution. Our analysis shows that for
$J/\psi$ production at the LHC, there is a significant event rate even for $p_T
\sim$~100~GeV. The measurement of the cross-section at such large values of
$p_T$ will provide a very important test of the fragmentation mechanism.


title: Quark resonances and high E_t jets

abstract:
  Possible spin-3/2 quark resonances would have a significant effect on high
E$_{\mbox{\rm t}}$ jet production through their contribution to the subprocess
$q+{\bar q}\rightarrow g+g$. Such enhancements are compared to a, recently
reported, anomaly in inclusive jet production at the CDF detector.


title:
Z Anomalous Couplings and the Polarization Asymmetry in $\gamma e \to
  Ze$

abstract:
  We extend our previous analysis of the sensitivity of the energy dependence
of the polarization asymmetry in $\gamma e \to W\nu$ to the possible existence
of anomalous trilinear gauge couplings to the $\gamma e \to Ze$ case. We find
that by combining the constraints imposed by both the energy dependence of the
total cross section and polarization asymmetry, strong limits on the anomalous
$\gamma ZZ$ couplings are obtainable at the Next Linear Collider. Further
constraints obtained from a consideration of the angular distribution are
briefly discussed.


title:
Supersymmetric QCD Corrections to Top Quark Pair Production in
  Photon-Photon Collision

abstract:
  Supersymmetric QCD corrections to top quark pair production by photon fusion
are calculated in the minimal supersymmetric standard model taking into account
of the effects of stops in the corrections to the total cross-section of t
anti-t production at the future electron-positron linear collider. We find that
the relative correction can be a few percent for reasonable values of the
parameters.


title:
On the MSW $\nu_e \to \nu_s$ transition solution of the solar neutrino
  problem

abstract:
  We study the stability of the two--neutrino MSW solution of the solar
neutrino problem, corresponding to solar $\nu_e$ transitions into sterile
neutrino, $\nu_e \rightarrow \nu_s$, with respect to changes of the total
fluxes of $^{8}$B and $^{7}$Be neutrinos, $\Phi_{{\rm B}}$ and $\Phi_{{\rm
Be}}$. For any value of $\Phi_{{\rm Be}}$ from the interval $0.7\Phi^{{\rm
BP}}_{{\rm Be}}\leq \Phi_{{\rm Be}} \leq 1.3\Phi^{{\rm BP}}_{{\rm Be}}$ (for
$\Phi_{{\rm Be}} = 0.7\Phi^{{\rm BP}}_{{\rm Be}}$) the $\nu_e \rightarrow
\nu_{s}$ MSW transitions provide at 95\% C.L. a description of the existing
solar neutrino data for $0.40~(0.39)~\Phi^{{\rm BP}}_{{\rm B}} \ltap \Phi_{{\rm
B}} \ltap 36~(40)\Phi^{{\rm BP}}_{{\rm B}}$, $\Phi^{{\rm BP}}_{{\rm B}}$ and
$\Phi^{{\rm BP}}_{{\rm Be}}$ being the fluxes in the solar model of
Bahcall--Pinsonneault from 1992. The corresponding allowed regions of values of
the parameters \dm2 and \sn2, characterizing the solar neutrino transitions,
are derived. The physical implications of the found MSW $\nu_e \rightarrow
\nu_s$ solutions for the future solar neutrino experiments are considered as
well.


title: Signatures for Squarks in the Light Gaugino Scenario

abstract:
  When the gluino is light and long lived, missing energy is a poor signature
for both squarks and gluinos. Instead, squark pair production leads to events
with $\ge 4$ jets. If a chargino can decay to squark and quark, missing energy
is also a poor signature for the chargino. Properties of 4-jet events
originating from squarks are discussed. ALEPH's preliminary report of an excess
of 4-jet events, with a peak in total dijet mass of 109 GeV, is analyzed in
terms of $S_q S_q^*$ and chargino pair production.


title: $V_{td}$ from Hadronic Two-Body $B$ Decays

abstract:
  Certain hadronic two-body decays of $B$ mesons are dominated by penguin
diagrams. The ratios of rates for several such decays, including $\Gamma(B^0
\to \overline{K}^{*0} K^0)/\Gamma(B^0 \to \phi K^0)$, $\Gamma(B^0 \to
\overline{K}^{*0} K^{*0})/\Gamma(B^0 \to \phi K^{*0})$, $\Gamma(B^+ \to
\overline{K}^{*0} K^+)$ $/\Gamma(B^+ \to \phi K^+)$, and $\Gamma(B^+ \to
\overline{K}^{*0} K^{*+})/\Gamma(B^+ \to \phi K^{*+})$, can provide information
on the ratio of Cabibbo-Kobayashi-Maskawa (CKM) elements $|V_{td}/V_{ts}|$ in a
manner complementary to other proposed determinations. SU(3) breaking effects
cancel in some ratios. The cases of neutral $B$ decays are free of corrections
from small annihilation terms.


title: Symmerty Non-restoration at High Temperature and Supersymmetry

abstract:
  We analyse the high temperature behaviour of softly broken supersymmetric
theories taking into account the role played by effective non-renormalizable
terms generated by the decoupling of superheavy degrees of freedom or the
Planck scale physics. It turns out that discrete or continuous symmetries,
spontaneously broken at intermediate scales, may never be restored, at least up
to temperatures of the cutoff scale. There are a few interesting differences
from the usual non-restoration in non-supersymmetric theories case where one
needs at least two Higgs fields and non-restoration takes place for a range of
parameters only. We show that with non-renormalizable interactions taken into
account the non-restoration can occur for any nonzero range of parameters even
for a single Higgs field. We show that such theories in general solve the
cosmological domain wall problem, since the thermal production of the dangerous
domain walls is enormously suppressed.


title:
Textured Minimal and Extended Supergravity Unification and Implications
  for Proton Stability

abstract:
  We construct a class of textured supergravity unified SU(5) models using
Planck scale corrections. We show that the texture constraints in the Higgs
doublet sector are insufficient in general to fully determine the textures in
the Higgs triplet sector. A classification of textured minimal parameter models
is given and their Higgs triplet textures computed under the constraint that
they possess the Georgi-Jarlskog textures in the Higgs doublet sector. It is
argued that additional dynamical assumptions are needed to remove the
ambiguity.The recently proposed extension of supergravity unification to
include a minimal exotic sector is free of this ambiguity and leads to unique
textures in the Higgs triplet sector. Implications for proton stability are
discussed.


title: Isospin Breaking Effects in the Anomalous Processes with Vector Mesons

abstract:
  We introduce isospin breaking terms as well as (SU(3)) breaking terms to the
anomalous (VVP) coupling in the hidden local symmetry scheme without affecting
the low energy theorem on the processes such as (\pi\to 2 \gamma) and
(\gamma\to 3\pi ). It is shown that the predictions from these terms coincide
successfully with all the experimental data of anomalous decays. It is also
predicted that the decay widths of (\rho^0 \to \pi^0 \gamma) and (\phi \to
\eta' \gamma) are (114\pm 7 keV) and (0.552 \pm 0.055 keV), respectively.


title: Semi-Analytical Approach to Off-Shell W and Z Pair Production

abstract:
  We give a short review of the results for four fermion production, which have
been obtained by the semi-analytical approach. The angular degrees of freedom
(typically five or more) are integrated over analytically while the
integrations over invariant fermion pair masses (typically two or more) remain
to be performed by numerical methods. In addition to doubly resonating cross
sections from virtual two boson production, QED corrections and background
contributions were determined. However, a large variety of final state
topologies has not been treated so far.


title:
A Renormalization Group Analysis of the Higgs Boson with Heavy Fermions
  and Compositeness

abstract:
  We study the properties of heavy fermions in the vector-like representation
of the electro-weak gauge group $SU(2)_W\times U(1)_Y$ with Yukawa couplings to
the standard model (SM) Higgs boson. Using the renormalization group analysis,
we discuss their effects on the vacuum stability and the triviality bound on
the Higgs self-coupling, within the context of the standard model (i.e., the
Higgs particle is elementary). Contrary to the low energy case where the
decoupling theorem dictates their behavior, the inclusion of heavy fermions
drastically change the SM structure at high scale. We also discuss the
interesting possibility of compositeness, i.e., the Higgs particle is composed
of the heavy fermions using the method of Bardeen, Hill and
Lindner~\cite{BHL91}. Finally we briefly comment on their possible role in
explaining $R_b$ and $R_c$.


title: Loop Induced Higgs Boson Pair Production at e+e- Colliders

abstract:
  We analyse the loop induced production of Higgs boson pairs at future
high--energy $e^+e^-$ colliders, both in the Standard Model and in its minimal
supersymmetric extension. The cross sections for Standard Model Higgs pair
production through $W/Z$ boson loops, $\ee \ra H^0 H^0$, are rather small but
the process could be visible for high enough luminosities, especially if
longitudinal polarization is made available. In the Minimal Supersymmetric
Standard Model, the corresponding processes of CP--even or CP--odd Higgs boson
pair production, $\ee \ra hh, HH, Hh$ and $\ee \ra AA$ have smaller cross
sections, in general. The additional contributions from chargino/neutralino and
slepton loops are at the level of a few percent in most of the supersymmetric
parameter space.


title:
Three flavor neutrino oscillation analysis of the kamiokande multi-gev
  atmospheric neutrino data

abstract:
  Using the published Kamiokande data of the multi-GeV atmospheric neutrinos,
we have searched the optimum set of the neutrino oscillation parameters among
three flavors. It is found that $\chi^2$ is minimized for ($\Delta m_{21}^2$,
$\Delta m_{31}^2$) = (3.8$\times 10^{-2}~$eV$^2$, 1.4$\times 10^{-2}~$eV$^2$),
($\theta_{12}$, $\theta_{13}$, $\theta_{23}$) =
($19^\circ$,$43^\circ$,$41^\circ$) with $\chi_{\rm min}$ = 3.2 (42\%CL). The
sets of parameters ($\Delta m_{21}^2$, $\Delta m_{31}^2$) = (${\cal
O}$($10^{-11}$eV$^2$) or ${\cal O}$($10^{-5}$eV$^2$), ${\cal
O}$($10^{-2}$eV$^2$)) which are suggested by the two flavor analysis fall
within 0.7$\sigma$.


title: Statistical Properties of the Linear Sigma Model

abstract:
  The statistical equilibrium properties of the linear sigma model are studied,
with a view towards characterizing the field configurations employed as initial
conditions for numerical simulations of the formation of disoriented chiral
condensates in high-energy nuclear collisions. The field is decomposed into its
spatial average (the order parameter) and the fluctuations (the quasi-
particles) and enclosed in a rectangular box with periodic boundary conditions.
The quantized quasi-particle modes are described approximately by Klein-Gordon
dispersion relations containing an effective mass that depends on both the
temperature and the magnitude of the order parameter. The thermal fluctuations
are instrumental in shaping the effective potential governing the order
parameter, and the evolution of its statistical distribution with temperature
is discussed, as is the behavior of the associated effective masses. As the
system is cooled the field fluctuations subside, causing a smooth change from
the high-temperature phase in which chiral symmetry is approximately restored
towards the normal phase. Of practical interest is the fact that the
equilibrium field configurations can be sampled in a simple manner, thus
providing a convenient means for specifying the initial conditions in dynamical
simulations of the non-equilibrium relaxation of the chiral field. The
corresponding correlation function is briefly considered and used to calculate
the spectral strength of radiated pions. Finally, by propagating samples of
initial configurations by the exact equation of motion, it has been ascertained
that the treatment is sufficiently accurate to be of practical utility.


title: Lorentz Boosts as Squeeze Transformations and Coherence Problems

abstract:
  The quark model and the parton model are known to be two different
manifestations of the same covariant entity. However, the interaction
amplitudes of partons are incoherent while they are coherent in the quark
model. According to Feynman, this is due to the dilation of the interaction
time among the quarks. We present a quantitative analysis of this time-dilation
problem using Lorentz boosts as squeeze transformations.


title: Heavy Quarkonium and nonperturbative corrections

abstract:
  We analyse the possible existence of non-perturbative contributions in heavy
$\bar Q Q$ systems ($\bar Q$ and $Q$ need not have the same flavour) which
cannot be expressed in terms of local condensates. Starting from QCD, with well
defined approximations and splitting properly the fields into large and small
momentum components, we derive an effective lagrangian where hard gluons (in
the non-relativistic aproximation) have been integrated out. The large momentum
contributions (which are dominant) are calculated using Coulomb type states.
Besides the usual condensate corrections, we see the possibility of new
non-perturbative contributions. We parametrize them in terms of two low
momentum correlators with Coulomb bound state energy insertions $E_n$. We
realize that the Heavy Quark Effective lagrangian can be used in these
correlators.
  We calculate the corrections that they give rise to in the decay constant,
the bound state energy and the matrix elements of bilinear currents at zero
recoil. We study the cut-off dependence of the new contributions and we see
that it matches perfectly with that of the large momentum contributions.
  We consider two situations in detail: i) $E_n>> \Lambda_{QCD}$ ($M_Q
\rightarrow \infty$) and ii) $E_n << \Lambda_{QCD}$, and briefly discuss the
expected size of the new contributions in $\Upsilon$ , $J/\Psi$ and
$B_{c}^{\ast}$ systems.


title:
$\eta$-Meson Decays and Strong $U_A(1)$ Breaking in the Three-Flavor
  Nambu-Jona-Lasinio Model

abstract:
  We study the $\eta \to \gamma \gamma$ and $\eta \to \pi^0 \gamma \gamma$
decays using an extended three-flavor Nambu-Jona-Lasinio model that includes
the 't~Hooft instanton induced interaction. We find that the $\eta$-meson mass,
the $\eta \to \gamma \gamma$ decay width and the $\eta \to \pi^0 \gamma \gamma$
decay width are in good agreement with the experimental values when the
$U_{A}(1)$ breaking is strong and the flavor $SU(3)$ singlet-octet mixing angle
$\theta$ is about zero. The effects of the $U_A(1)$ breaking on the baryon
number one and two systems are also studied.


title: Hadronic production of S- and P-wave states of (b-bar c)-quarkonium

abstract:
  In the leading $O(\alpha_s^4)$ order of the perturbative QCD, the hadronic
production cross-sections of $S$- and $P$-wave states of $B_c$ meson are
calculated. The results for the $S$-wave levels are compared with the values
given in other papers as well as in the model of the $b$ quark fragmenatation
into $B_c$. In the given order, the cross-sections of the hadronic production
of the $P$-wave states are calculated for the first time. Their contribution
into the $B_c$ meson production is less than 10\%. There is a strong difference
between the predictions of the fragmentation model and the exact perturbative
calculations. These difeerences are discussed in details for the differential
distributions over various kinematical quantities.


title:
$D$,$D^*(2010)$ and $D^{*}_{2}(2460)$ charmed mesons production in
  hadron--hadron collisions

abstract:
  A resently developed generalization of the Quark--Gluon String Model to the
case of bosonic resonances production in hadron--hadron collisions is used for
the calculation of inclusive production of charmed mesons $D$, $D^*(2010)$ and
$D^{*}_{2}(2460)$. A simple relation which determines the dependence of the
charmed meson production cross sections on their spin J is obtained. It is
shown that the theoretical predictions for the inclusive spectra and production
cross sections of these charmed mesons are confirmed experimentally with a
reasonable accuracy.


title: Implications of supersymmetric models with natural R-parity conservation

abstract:
  In the minimal supersymmetric standard model, the conservation of R-parity is
phenomenologically desirable, but is ad hoc in the sense that it is not
required for the internal consistency of the theory. However, if B-L is gauged
at very high energies, R-parity will be conserved automatically and exactly,
provided only that all order parameters carry even integer values of 3(B-L). We
propose a minimal extension of the supersymmetric standard model in which
R-parity conservation arises naturally in this way. This approach predicts the
existence of a very weakly coupled, neutral chiral supermultiplet of particles
with electroweak-scale masses and lifetimes which may be cosmologically
interesting. Neutrino masses arise via an intermediate-scale seesaw mechanism,
and a solution to the $\mu$ problem is naturally incorporated. The apparent
unification of gauge couplings at high energies is shown to be preserved in
this approach. We also discuss a next-to-minimal extension, which predicts a
pair of electroweak-scale chiral supermultiplets with electric charge 2.


title: Macroscopic Forces from Supersymmetry

abstract:
  We argue that theories in which supersymmetry breaking originates at low
energies often contain scalar particles that mediate coherent gravitational
strength forces at distances less than a cm. We estimate the strength and range
of these forces in several cases. Present limits on such forces are inadequate.
However new techniques, such as those based on small cryogenic mechanical
oscillators, may improve the present limits by ten orders of magnitude or
discover new forces as weak as 1 \% of gravity at distances down to 40 microns.


title: WW Cross-sections and Distributions

abstract:
  We present the results obtained by the "WW Cross-sections and Distributions"
working group during the CERN Workshop "Physics at LEP2" (1994/1995)


title: Determination of the mass of the W boson

abstract:
  Previous studies of the physics potential of LEP2 indicated that with the
design luminosity of 500 inverse picobarn one may get a direct measurement of
the mass of the W-boson with a precision in the range 30 - 50 MeV. This report
presents an updated evaluation of the estimated error on the mass of the
W-boson based on recent simulation work and improved theoretical input. The
most efficient experimental methods which will be used are also described.


title:
Dispersive Approach to Semileptonic Form-Factors in Heavy-to-Light Meson
  Decays

abstract:
  We study the semileptonic decays of heavy mesons into light pseudoscalars by
making use of dispersion relations. Constraints from heavy quark symmetry,
chiral symmetry and perturbative QCD are implemented into a dispersive model
for the form-factors. Large deviations from $B^*$-pole dominance are observed
in $B\to\pi\ell\nu$. We discuss the model prediction for this mode and its
possible impact on the extraction of $|V_{ub}|$.


title:
Light $\stop\to\wino b$ models are not ruled out by the Tevatron top
  experiments

abstract:
  SUSY events in which a light stop decays to a chargino may manage to pass the
cuts designed for top counting experiments at the Tevatron with no significant
diminution of signal. Events in which a top decays via stop are detected with
fair efficiency compared to SM top events when $\stop\into b\wino$. More
importantly, direct pair production of light stops contributes significantly to
the cut samples. Many SUSY models with stops lighter than 100 GeV are viable
even for $\Gamma(t\into\stop) \approx \Gamma(t\into bW)$.


title: Leptoquarks in $e^-\gamma$ Collisions

abstract:
  We discuss the leptoquark discovery potential of $e^-\gamma$ scattering and
show how polarization and angular distributions can be used to differentiate
the different types of leptoquarks.


title:
The evolution of parton distributions beyond leading order: the singlet
  case

abstract:
  A complete description of the calculation of anomalous dimensions (GLAP
splitting functions) is given for parton distributions which appear in
space-like processes. The calculation is performed in the light-cone gauge. The
results are in agreement with the previous results of Furmanski and Petronzio.


title: Electrical conductivity in the early universe

abstract:
  We solve numerically the Boltzmann equation in the early universe in the
presence of a constant electric field and find the electrical conductivity
$\sigma$ in the range $1\MeV\lsim T\lsim M_W$. The main contribution to
$\sigma$ is shown to be due to leptonic interactions. For $T\lsim 100\MeV$ we
find $\sigma\simeq 0.76T$ while at $T\simeq M_W$ we obtain $\sigma\simeq 6.7T$


title: A Dynamical Model of Color Confinement

abstract:
  A dynamical model of confinement based on a transport theoretical description
of the Friedberg-Lee model is extended to explicit color degrees of freedom.
The string tension is reproduced by an adiabatic string formation from the
nucleon ground state. Color isovector oscillation modes of a $q\bar{q}$-system
are investigated for a wide range of relative $q\bar{q}$-momenta and the
dynamical impact of color confinement on the quark motion is shown.


title: Quantum Corrections to Baryon Properties in Chiral Soliton Models

abstract:
  We present a procedure to calculate 1-loop graphs in the soliton sector of
chiral Lagrangians and use it to calculate quantum corrections to certain
baryon observables in Skyrme-type models. Results generally show an improvement
over the values obtained in tree approximation except for the case of the axial
coupling g_A.


title: f_B^{stat} and \mu_\pi^2 in quasiclassical approximation of sum rules

abstract:
  In the framework of sum rules with a use of quarkonium mass spectrum,
evaluated in the quasiclassical approximation, estimates of leptonic constant
$f_B^{stat}\simeq 320\pm 60$ MeV in a static limit and for the average heavy
quark momentum squared $\mu_\pi^2 \simeq 0.5\pm 0.1$ GeV$^2$ are obtained.


title: Heavy quark-meson mass gap from spectroscopy

abstract:
  Using a quite accurate flavour-independence of $nS$-level mass differences in
heavy quarkonia and a corresponding quasiclassical expression for the heavy
quark binding energy, one shows that experimental data on masses of mesons with
heavy quarks allow one to make the estimate $\bar \Lambda= 0.63\pm 0.03$ GeV.


title:
Quark Mass Corrections to the Bjorken and Gross--Llewellyn-Smith Sum
  Rules

abstract:
  Quark mass corrections to the spin partonic structure function g_1(x,Q^2) and
function F_3(x,Q^2) are obtained at the order O(alpha_s) along with the
coefficient functions C^{(A)} and C^{(V)} related to the Bjorken and
Gross--Llewellyn-Smith sum rules. In the massless limit the difference between
F_3 and g_1 is encountered to be (alpha_s/\pi)*CF*(1-x). The results for the
functions C^{(A)} and C^{(V)} at m=0 agree with the previous MS-scheme
calculations C^{(A)}=C^{(V)}=1-(3*alpha_s/4\pi)*CF.


title: Quark-Antiquark Production in DIS Diffractive Dissociation

abstract:
  We calculate the cross section for the production of two jets with large
transverse momenta $\kf^2$ in DIS diffractive dissociation for both transverse
and longitudinally polarized photons. The scale which defines the hardness of
the pomeron is found to be $\kf^2\frac{Q^2+M^2}{M^2}$. We present analytic
expressions and discuss numerical results relevant for the diffractive
dissociation at HERA.


title: A Supersymmetric Theory of Flavor and R Parity

abstract:
  We construct a renormalizable, supersymmetric theory of flavor and $R$ parity
based on the discrete flavor group $(S_3)^3$. The model can account for all the
masses and mixing angles of the Standard Model, while maintaining sufficient
squark degeneracy to circumvent the supersymmetric flavor problem. By starting
with a simpler set of flavor symmetry breaking fields than we have suggested
previously, we construct an economical Froggatt-Nielsen sector that generates
the desired elements of the fermion Yukawa matrices. With the particle content
above the flavor scale completely specified, we show that all renormalizable
$R$-parity-violating interactions involving the ordinary matter fields are
forbidden by the flavor symmetry. Thus, $R$ parity arises as an accidental
symmetry in our model. Planck-suppressed operators that violate $R$ parity, if
present, can be rendered harmless by taking the flavor scale to be $\lesssim 8
\times 10^{10}$ GeV.


abstract:
  The structure functions of longitudinal virtual photon at low virtualities
are calculated in the framework of chiral pertubation theory(ChPT) in the zero
and first order of ChPT. It is assumed that the virtuality of target
longitudinal photon is much less than the virtuality of the hard projectile
photon and both are less than the characteristic ChPT scale.


title: The ratios of the light quark masses

abstract:
  The paper collects the various pieces of information concerning the relative
size of m_u, m_d and m_s. A coherent picture results, which constrains the mass
ratios to a rather narrow range: m_u/m_d = 0.553 \pm 0.043, m_s/m_d = 18.9 \pm
0.8.


title: Chiral Symmetry Breaking in the Dual Ginzburg-Landau Theory

abstract:
  Confinement and chiral symmetry breaking are the most fundamental phenomena
in Quark Nuclear Physics, where hadrons and nuclei are described in terms of
quarks and gluons. The dual Ginzburg-Landau (DGL) theory, which contains
monopole fields as the most essential degrees of freedom and their condensation
in the vacuum, is modeled to describe quark confinement in strong connection
with QCD. We then demonstrate that the DGL theory is able to describe the
spontaneous break down of the chiral symmetry.


title: Monopole Dominance for Nonperturbative QCD

abstract:
  Monopole dominance for the nonperturbative features in QCD is studied both in
the continuum and the lattice gauge theories. First, we study the dynamical
chiral-symmetry breaking (D$\chi $SB) in the dual Higgs theory using the
effective potential formalism. We find that the main driving force for D$\chi
$SB is brought from the confinement part in the nonperturbative gluon
propagator rather than the short-range part, which means monopole dominance for
D$\chi $SB. Second, the correlation between instantons and QCD-monopoles is
studied. In the Polyakov-like gauge, where $A_4(x)$ is diagonalized, the
QCD-monopole trajectory penetrates the center of each instanton, and becomes
complicated in the multi-instanton system. Finally, using the SU(2) lattice
gauge theory with $16^4$ and $16^3 \times 4$, the instanton number is measured
in the singular (monopole-dominating) and regular (photon-dominating) sectors,
respectively. Instantons and anti-instantons only exist in the monopole sector
both in the maximally abelian gauge and in the Polyakov gauge, which means
monopole dominance for the topological charge.


title: Neutrino Properties

abstract:
  A brief sketch is made of the present observational status of neutrino
properties, with emphasis on the hints from solar and atmospheric neutrinos, as
well as cosmological data on the amplitude of primordial density fluctuations.
Implications of neutrino mass in particle accelerators, astrophysics and
cosmology are discussed.


title:
The connection between the nuclear matter mean-field equation of state
  and the quark and gluon condensates at high density

abstract:
  It is known now that chiral symmetry restoration requires the meson-nucleon
coupling to be density dependent in nuclear-matter mean-field models. We
further show that quite generally, the quark and gluon condensates in medium
are related to the trace of energy-momentum tensor of nuclear matter and in
these models the incompressibility, K, must be less than thrice the chemical
potential, $\mu$. In the critical density $\rho _c$, the gluon condensate is
only reduced by $20\%$ indicating a larger effective nucleon mass.


title: New Predictions for Neutrino Telescope Event Rates

abstract:
  Recent measurements of the small-$x$ deep-inelastic regime at HERA translate
to new expectations for the neutrino-nucleon cross section at ultrahigh
energies. We present event rates for large underground neutrino telescopes
based on the new cross section for a variety of models of neutrino production
in Active Galactic Nuclei, and we compare these rates with earlier cross
section calculations.


title:
Electromagnetic form factors of nucleons in a relativistic three-quark
  model

abstract:
  We report the calculation of electromagnetic form factors of nucleons within
a relativistic three-quark model with Gaussian shape for the nucleon-quark
vertex. The allowed region for two adjustable parameters, the range parameter
$\Lambda_N$ in the Gaussian and the constituent quark mass $m_q$, is obtained
from fitting the data for magnetic moments and electromagnetic radii of
nucleons. The shapes of electric and magnetic nucleon form factors calculated
in this approach with the central parameters $m_q$=420 MeV and $\Lambda_N$=1.25
GeV are close to the data for momentum transfers $0\le Q^2\le 1$ GeV$^2$


title:
Production of a Prompt Photon in Association with Charm at
  Next-to-Leading Order in QCD

abstract:
  A second order, $O(\alpha ^2_s)$, calculation in perturbative quantum
chromodynamics of the two particle inclusive cross section is presented for the
reaction $p +\bar{p}\rightarrow \gamma + c + X$ for large values of the
transverse momentum of the prompt photon and charm quark. The combination of
analytic and Monte Carlo integration methods used here to perform phase-space
integrations facilitates imposition of photon isolation restrictions and other
selections of relevance in experiments. Differential distributions are provided
for various observables. Positive correlations in rapidity are predicted.


title: Production of Heavy Quarkonium in High Energy Colliders

abstract:
  Recent data from the Tevatron has revealed that the production rate of prompt
charmonium at large transverse momentum is orders of magnitude larger than the
best theoretical predictions of a few years ago. These surprising results can
be understood by taking into account two recent developments that have
revolutionized the theoretical description of heavy quarkonium production. The
first is the realization that fragmentation must dominate at large transverse
momentum, which implies that most charmonium in this kinematic region is
produced by the hadronization of individual high-$p_T$ partons. The second is
the development of a factorization formalism for quarkonium production based on
nonrelativistic QCD that allows the formation of charmonium from color-octet $c
\bar c$ pairs to be treated systematically. This review summarizes these
theoretical developments and their implications for quarkonium production in
high energy colliders.


title: Chiral Symmetry Breaking by Instantons

abstract:
  This is a review of the QCD instanton vacuum. After introducing instantons
and their physical meaning, I show that the number of instantons in the vacuum
fluctuates in accordance with the QCD trace anomaly. The main properties of the
instanton ensemble are given. Chiral symmetry breaking by instantons is
explained in three different though mathematically equivalent ways. In
particular, a derivation of the Nambu--Jona-Lasinio-type model from instantons
is presented, and the effective chiral lagrangian to which QCD is reduced at
low momenta, is given. I end up by discussing possible confinement mechanisms.


title: B to J/Psi+X in the Inclusive Parton and the ACCMM Model

abstract:
  The parton model as developed for semileptonic B decays is applied to the
inclusive decay B to J/Psi+X. We calculate the momentum spectrum of the J/Psi
using a one-parameter distribution function for the heavy quark, taken from
production experiments, and compare our results with recent data from CLEO
which fixes the distribution parameter epsilon_p. An analogous calculation is
carried out in the ACCMM model where the data determines the Fermi motion
parameter p_f. The models give a good description of the data, provided in each
of them the parameter in the distribution function is chosen to correspond to a
softer b quark momentum distribution than that commonly used in studies of
semileptonic B decays. In particular we arrive at epsilon_p = O(0.008) and p_f
= O(0.55 GeV), respectively. The latter value (p_f = 0.5 GeV) produces in the
ACCMM model 10^2*|V_ub/V_cb|^2=1.03, which removes a former supposed
discrepancy with the ISGW model. Finally, the strength of the effective color
singlet coefficient is found to be a_2 = O(0.28) in both models.


title:
OPE analysis of the nucleon scattering tensor including weak interaction
  and finite mass effects

abstract:
  We perform a systematic operator product expansion of the most general form
of the nucleon scattering tensor $W_{\mu \nu}$ including electro-magnetic and
weak interaction processes. Finite quark masses are taken into account and a
number of higher-twist corrections are included. In this way we derive
relations between the lowest moments of all 14 structure functions and matrix
elements of local operators. Besides reproducing well-known results, new sum
rules for parity-violating polarized structure functions and new mass
correction terms are obtained.


title: SUSY-QCD Decays of Squarks and Gluinos

abstract:
  The partial widths are determined for squark decays to gluinos and quarks,
and gluino decays to squarks and quarks, respectively. The widths are
calculated including one-loop SUSY-QCD corrections. The corrections amount to
$+$30\% to $+$50\% for squark decays and $-$10\% to $+$10\% for gluino decays.
We have derived the results in the \DR ~and \MS ~renormalization schemes, and
we have demonstrated explicitly that the one-loop effective $qqg$ and $q\sq\gl$
couplings are equal in the limit of exact supersymmetry.


title: Nuclear Modifications of Double Spin Asymmetries

abstract:
  We compute nuclear spin dependent structure functions using a dynamical model
for bound nucleon densities and hence calculate nuclear modifications to
asymmetries observed in recent doubly polarised deep inelastic scattering
experiments. We conclude that while the individual densities are changed
substantially by nuclear effects, the asymmetries themselves are largely
insensitive to these changes.


title: Electroweak Theory

abstract:
  In these lectures we give a discussion of the structure of the electroweak
standard model and its quantum corrections for tests of the electroweak theory.
The predictions for the vector boson masses, neutrino scattering cross sections
and the $Z$ resonance observables are presented in some detail. We show
comparisons with the recent experimental data and their implications for the
present status of the Standard Model. Finally we address the question how
virtual New Physics can influence the predictions for the precision observables
and discuss the minimal supersymmetric standard model as a special example of
particular theoretical interest.


title:
R-parity Violation Effects through Soft Supersymmetry Breaking Terms and
  the Renormalisation Group

abstract:
  We present full renormalisation group equations for the MSSM with R-parity
violation, including all soft supersymmetry breaking terms. The inclusion of
dimensionless R-parity violating couplings can generate many possible low
energy effects through the generation of off-diagonal soft masses violating
lepton and quark flavour, and through the generation of lepton-Higgs mixing. We
discuss the relation between the weak and unification scale R-parity violation
and study the effects on neutrino mass generation and $\mu\to e\gamma$.


title: Neutrino Decay of Positronium in the Standard Model and Beyond

abstract:
  Whether in the Standard Model or beyond it, neutrinos contribute to the
invisible decay mode of orthopositronium but practically not at all to that of
parapositronium. Although this remark does not resolve the orthopositronium
decay puzzle, it allows for upper bounds to be set on neutrino magnetic
moments.


title: Possible tests of neutrino maximal mixing and comments on matter effects

abstract:
  We show in a simple and general way that matter effects do not contribute to
the averaged value of the probabilities of transition of solar $\nu_e$'s into
other states in the case of maximal mixing of any number of massive neutrinos.
We also show that future solar neutrino experiments (Super-Kamiokande and SNO)
will allow to test the model with maximal mixing of three massive neutrinos in
a way that does not depend on the initial solar neutrino flux.


title:
The MSW solution to the solar neutrino problem in the presence of random
  solar matter density perturbations

abstract:
  We present the evolution equation describing MSW conversion, derived in the
framework of the Schr\"odinger approach, in the presence of matter density
fluctuations. Then we analyse the effect of such fluctuations in the MSW
scenario as a solution to the solar neutrino problem. It is shown that the
non-adiabatic MSW parameter region is rather stable (especially in $\delta
m^2$) for matter density noise at the few percent level. We also discuss the
possibility to probe solar matter density fluctuations at the future Borexino
experiment.


title: The Zero Temperature Chiral Phase Transition in SU(N) Gauge Theories

abstract:
  We investigate the zero temperature chiral phase transition in an SU(N) gauge
theory as the number of fermions $N_f$ is varied. We argue that there exists a
critical number of fermions $N_f^c$, above which there is no chiral symmetry
breaking or confinement, and below which both chiral symmetry breaking and
confinement set in. We estimate $N_f^c$ and discuss the nature of the phase
transition.


title:
Three flavor neutrino oscillation constraints from accelerator, reactor,
  atmospheric and solar neutrino experiments

abstract:
  We discuss constraints on three flavor neutrino mixings from the accelerator
and reactor experiments, the Kamiokande multi-GeV data, and the solar neutrino
observations. The LSND result is excluded at 90\%CL by the constraints imposed
by all the data of reactor and accelerator experiments and the Kamiokande
multi-GeV data if the mass scale required for the solution to the solar
neutrino problem is hierarchically small. The region of a set of the effective
two-flavor mixing parameters ($\Delta m^2$, $\sin^22\theta$) is given for the
channel $\nu_\mu\rightarrow\nu_e$ which is allowed at 90\%CL by the multi-GeV
Kamiokande data alone.


title: Single W-boson production in e-\gamma colliders

abstract:
  Single $W$-boson production in $e^-\gamma$ collisions with polarized beams is
investigated. In the framework of the Standard Model the updated estimates for
the measurement precision of photon anomalous coupling parameters $ \kappa_{
\gamma},$ $ \lambda_{ \gamma}$ at the Next Linear Collider with $ \sqrt{s_{
e\gamma }}=420$ GeV are obtained. The production of right-handed gauge bosons $
W^-_{ 2 }$ in this collision mode is also analysed. If the associated neutrino
is light, the channel would give the best discovery reach for $ W^-_{ 2 }$ in
the Next Linear Collider.


title: Baryogenesis and Polyakov line condensate during inflation

abstract:
  The thermal average of the Polyakov line is non-zero at high temperature. It
has been suggested that its phase could be relevant for baryogenesis within the
standard model, providing a source of spontaneously broken CP violation. This
scenario suffers from a causal domain problem which cannot be cured by
inflation: quantum fluctuations in de Sitter space overwhelm the periodicity of
the potential.


title: R-Parity Violation and Peccei-Quinn Symmetry in GUTS

abstract:
  We address the question whether it is possible in GUTs to obtain R-parity
violation with a large ${\Delta L{/}\Delta B}$ hierarchy of strengths so that
the proton is stable while phenomenologically interesting $L$-violation is
present. We consider versions of SU(5) with a built-in Peccei-Quinn symmetry
spontaneously broken at an intermediate scale. The P-Q symmetry and the field
content guarantee a large suppression of the effective $B$-violating terms by a
factor $\Lambda^3_{PQ}/M_PM^2_X $ while the effective $L$-violating terms stay
large.


title: Topflavor: A Separate SU(2) for the Third Family

abstract:
  We consider an extended electroweak gauge group: SU(2)$_1 \times$ SU(2)$_2
\times$ U(1)$_Y$ where the first and second generation of fermions couple to
SU(2)$_1$ and the third generation couples to SU(2)$_2$. Bounds based on heavy
gauge boson searches and current precision electroweak measurements are placed
on the masses of the new heavy gauge bosons. In particular we find that the
mass of the heavy W boson can not be less than 800 GeV. For some range of the
allowed parameter space, these heavy gauge bosons produce observable signals at
the Tevatron and LEP-II.


title:
Two-loop renormalization group analysis of supersymmetric SO(10) models
  with an intermediate scale

abstract:
  Two-loop evolutions of the gauge couplings in a class of intermediate scale
supersymmetric SO(10) models including the effect of third generation Yukawa
couplings are studied. The unification scale, the intermediate scale and the
value of the unification gauge coupling in these models are calculated and the
gauge boson mediated proton decay rates are estimated. In some cases the
predicted proton lifetime turns out to be in the border-line of experimental
limit. The predictions of the top quark mass, the mass ratio $m_b(m_b)/
m_\tau(m_\tau)$ from the two-loop evolution of Yukawa couplings and the mass of
the left handed neutrino via see-saw mechanism are summarized. The lower bounds
on the ratio of the VEVs of the two low energy doublets ($\tan\beta$) from the
requirement of the perturbative unitarity of the top quark Yukawa coupling up
to the grand unification scale are also presented. All the predictions have
been compared with those of the one-step unified theory.


title: Hyperon Polarization in the Constituent Quark Model

abstract:
  We consider mechanism for hyperon polarization in inclusive production. The
main role belongs to the orbital angular momentum and polarization of the
strange quark-antiquark pairs in the internal structure of the constituent
quarks. We consider a nucleon as a core consisting of the constituent quarks
embedded into quark condensate. The nonperturbative hadron structure is based
on the results of chiral quark models.


title: Event Generators for Bhabha Scattering

abstract:
  The results obtained by the "Event Generators for Bhabha Scattering" working
group during the CERN Workshop "Physics at LEP2" (1994/1995) are presented.


title: Low-energy dynamics of the $\gamma\gamma\to\pi\pi$ reaction

abstract:
  We calculate the one-quark-loop amplitude for the low energy
$\gamma\gamma\to\pi\pi$ collision in the context of the Nambu and Jona-Lasinio
model with scalar and pseudoscalar four quark couplings to all orders in the
external momenta. We show that the NJL predictions for the
$\gamma\gamma\to\pi^+\pi^-$ reaction are not far from the Born amplitude, which
is close to the data, and is compatible with the chiral perturbation theory
estimations. We determine the corrections given by the NJL model in leading
order of $1/N_c$ to the chiral loop amplitude for $\gamma\gamma\to\pi^0\pi^0$.
Numerical results for the $\gamma\gamma\rightarrow\pi\pi$ cross sections and
for pion polarizabilities are given.


title: $R$-Parity Breaking Phenomenology

abstract:
  We review various features of the $R$-parity breaking phenomenology, with
particular attention to the low energy observables, and to the patterns of the
$R$-parity breaking interactions that arise in Grand Unified models.


title:
Small-threshold behaviour of two-loop self-energy diagrams: two-particle
  thresholds

abstract:
  The behaviour of two-loop two-point diagrams at non-zero thresholds
corresponding to two-particle cuts is analyzed. The masses involved in a cut
and the external momentum are assumed to be small as compared to some of the
other masses of the diagram. By employing general formulae of asymptotic
expansions of Feynman diagrams in momenta and masses, we construct an algorithm
to derive analytic approximations to the diagrams. In such a way, we calculate
several first coefficients of the expansion. Since no conditions on relative
values of the small masses and the external momentum are imposed, the threshold
irregularities are described analytically. Numerical examples, using diagrams
occurring in the Standard Model, illustrate the convergence of the expansion
below the first large threshold.


title:
A Monte Carlo algorithm for Multiphoton Beamstrahlung in Monte Carlo
  event generators

abstract:
  We describe a simple algorithm that calculates the distributions of electrons
and positrons under multiphoton beamstrahlung at a future linear collider. The
evolution equation as given by Chen is solved by a Monte Carlo algorithm.
Explicit multiple beamstrahlung photons are generated. We present first results
from an implementation of beamstrahlung into the Monte Carlo event generator
{\tt WOPPER}, that calculates the QED radiative corrections to the process
$e^+e^- \to 4$~fermions through resonating W pairs.


title: Neutrino Oscillations and the MSW effect in Random Solar Matter

abstract:
  We investigate the effects of random density fluctuations on neutrino
oscillations in the Sun environment. We show how the average of certain
quantities which can be used to describe the MSW effect can be computed
analytically. We examine also the hypothesis commonly accepted that only
perturbations inside the resonance layer can have relevance. The average
amplitud, which gives the ''coherent probability'', is computed in an
analytical and exact way for the case of colored $\delta$-correlated gaussian
noise: the random perturbation induces a renormalization of the matter density
which adquires an imaginary part proportional to the fluctuation amplitud at
the resonance region. Integral equations are given for the density matrix of
the system in the ''optical'' approximation.
  PACS: 96.60.Kx, 02.50.Ey, 14.60.Pq,95.30.Cq, 96.60.Hv,14.60.Gh.


title: Towards the Non-Chiral Extension of SM and MSSM

abstract:
  We show that in some SU(N) type GUTs with the complementary pairs of the
conjugated fermion multiplets there naturally appear the relatively light
($M\ll M_{GUT}$) vectorlike fermions which considerably modify the desert
physics. In the non-SUSY case they can provide for the unification of the
standard coupling constant $\alpha_1$, $\alpha_2$ and $\alpha_S$ whereas in the
SUSY case they can increase the unification point up to the string unification
limit and decrease $\alpha_S(M_Z)$ down to the value predicted from the low
energy physics.


title: Pion Decay Constant at Finite Temperature in the Nonlinear Sigma Model

abstract:
  We calculate the pion decay constant near the critical temperature of the
$O(N)$ nonlinear sigma model in the large $N$ limit. Making use of the known
low temperature behavior, we construct a Pad\'{e} approximant to obtain the
behavior of $f_\pi(T)$ at all temperatures.


title: Chiral Perturbation Theory

abstract:
  An introduction to the methods and ideas of Chiral Perturbation Theory is
presented in this talk. The discussion is illustrated with some
phenomenological predictions that can be compared with available experimental
results.


title: Atmospheric muons and neutrinos from charm

abstract:
  We have updated our previous investigation of the production of muons and
neutrinos in cosmic ray interactions with the atmosphere, taking account of
recent results from the $ep$ collider HERA in our QCD-based model for hadronic
interactions. Qualitatively, our previous results remain unmodified: our
predictions for the conventional muon and neutrino fluxes agree with earlier
calculations, whereas the charm particle treatment we use gives significantly
lower prompt fluxes compared to earlier estimates. This implies better
prospects for detecting very high energy neutrinos from cosmic sources.


title: Direct detection of neutralino dark matter and b->s+gamma decays

abstract:
  We analyze the direct detection rate of minimal supersymmetric neutralino
dark matter in germanium, sapphire and sodium iodide detectors, imposing
cosmological and accelerator bounds including those from \bsg\ decay. In
contrast with several other recent analyses we find models with light charged
higgsinos and large stop mixing in which the counting rate in solid state
detectors exceeds 10 events/kg/day.


title: Consistency Condition for the Pinch Technique Self-Energies at Two Loops

abstract:
  A simple and testable necessary condition for the gauge independence of the
Pinch Technique self-energies at two loops is discussed. It is then shown that,
in the case of the $Z$ and $W$ self-energies, the condition is indeed satisfied
by the Papavassiliou-Pilaftsis formulation.


title:
Chiral symmetry at finite temperature: linear vs nonlinear
  $\sigma$-models

abstract:
  The linear O($N$) sigma model undergoes a symmetry restoring phase transition
at finite temperature. We show that the nonlinear O($N$) sigma model also
undergoes a symmetry restoring phase transition; the critical temperatures are
the same when the linear model is treated in mean field approximation and the
nonlinear model is treated to leading plus subleading order in the 1/$N$
expansion. We also carefully define and study the behavior of $f_{\pi}$ and the
scalar condensate at low temperatures in both models, showing that they are
independent of field redefinition.


title: Remarks on the Upper Bounds on the Higgs Boson Mass from Triviality

abstract:
  We study the effects of the one-loop matching conditions on Higgs boson and
top quark masses on the triviality bounds on the Higgs boson mass using
$\beta_{\lambda}$ with corrected two-loop coefficients. We obtain quite higher
results than previous ones and observe that the triviality bounds are not
nearly influenced by varying top quark mass over the range measured at CDF and
D0. The effects of typo errors in $\beta_{\lambda}^{(2)}$ and the one-loop
matching condition on the top quark mass are negligible. We estimate the size
of effects on the triviality bounds from the one-loop matching condition on the
Higgs boson mass.


title:
Common origin of the shoulder in multiplicity distributions and of
  oscillations in the factorial cumulants to factorial moments ratio

abstract:
  The shoulder structure of charged particles multiplicity distributions (MD's)
in full phase space in $e^+e^-$ annihilation at the $Z_0$ peak and the
quasi-oscillatory behavior of the ratio of factorial cumulants over factorial
moments, $H_q$, as a function of the order $q$, are quantitatively reproduced
within a simple parametrization of the MD in terms of a weighted superposition
of two Negative Binomial Distributions, associated to two- and multi-jet
production, i.e., to hard gluons radiation.


title: Fully Relativistic Quark Models for Heavy-Light Systems

abstract:
  A fully relativistic quark model is constructed and applied to the study of
wave-functions as well as the spectrum of heavy-light mesons. The free
parameters of the model are a constituent quark mass and (on the lattice) an
adjustable r-parameter in the fermionic kinetic energy, while the confinement
is introduced via potentials measured by MonteCarlo. The results are compared
to Monte Carlo energies and Coulomb-gauge wave functions. They are in very good
agreement with the data. A comparison with previous models suggests that we are
seeing in the Monte Carlo data the quantum-relativistic delocalization of the
quark due to Zitterbewegung.


title:
Complete Initial State QED Corrections to Off-Shell Gauge Boson Pair
  Production in e+e- Annihilation

abstract:
  We study Standard Model four-fermion production in e+ e- annihilation at LEP2
energies and above using a semi-analytical approach. We derive the complete QED
initial state corrections (ISR) to the reactions e+e- -> ZZ ->
$f_1\bar{f_1}f_2\bar{f_2}$ and e+e- -> W+W- -> ${\bar f}_1^u f_1^d f_2^u {\bar
f}_2^d$ with $f_1\neq f_2$~and $f_i \neq e^\pm, \nu_e$. As compared to the
well-known universal s-channel ISR, additional complexity arises due to
non-universal, process-dependent ISR contributions from t- and u-channel
fermion exchanges. The full set of formulae needed to perform numerical
calculations is given together with samples of numerical results.


title: Scale Setting in Top Quark Decays

abstract:
  We compute the $O(\beta_0 \alpha_s^2)$ QCD corrections to the Standard Model
decay $t\rightarrow W^+ b$ as well as the non standard decay $t\rightarrow H^+
b$. We then use our results to compute the BLM scale for these decays, and
study the dependence of the BLM scale on the mass of the boson in the decay. We
find that the BLM procedure gives extremely small scales when top decays into
heavy bosons. When we try to improve the BLM scale by reexpressing rates as a
functions of the top quark running mass, we find the BLM scale exhibits
unnatural dependence on the boson mass, casting doubts on the applicability of
the BLM procedure to these processes.


title: Comparative Study of the Hadronic Production of $B_c$ Mesons

abstract:
  A comparative study of the full $\alpha_s^4$ perturbative QCD calculation of
the hadronic production of the $B_c$ and $B_c^*$ mesons and the fragmentation
approximation is presented. We examined the various subprocesses in detail and
the distribution $C(z)$, where $z$ is twice the fraction of the $B_c$ or
$B_c^*$ meson energy in the center of mass of the subprocess, which proved
insightful and revealed the importance of certain non-fragmentation
contributions. We concluded that the condition for the applicability of the
fragmentation approximation in hadronic collisions is that the transverse
momentum $P_T$ of the produced $B_c$ and $B_c^*$ be much larger than the mass
of the $B_c$ meson; i.e., $P_T\gg M_{B_c}$. Numerical results for the cross
sections at the Fermilab Tevatron are also presented using updated parton
distribution functions with various kinematic cuts.


title: The System of Multi Color-flux-tubes in the Dual Ginzburg-Landau Theory

abstract:
  We study the system of multi color-flux-tubes in terms of the dual Ginzburg
-Landau theory. We consider two ideal cases, where the directions of all the
color-flux-tubes are the same in one case and alternative in the other case for
neighboring flux-tubes. We formulate the system of multi color-flux -tubes by
regarding it as the system of two color-flux-tubes penetrating through a two
dimensional sphere surface. We find the multi flux-tube configuration becomes
uniform above some critical flux-tube number density $\rho_c = 1.3 \sim 1.7
{\rm fm}^{-2}$. On the other hand, the inhomogeneity on the color electric
distribution appears when the flux-tube density is smaller than $\rho_c$. We
discuss the relation between the inhomogeneity in the color-electric
distribution and the flux-tube number density in the multi-flux-tube system
created during the QGP formation process in the ultra-relativistic heavy-ion
collision.


title:
QCD Phase Transition and Hadron Bubble Formation in the Dual
  Ginzburg-Landau Theory

abstract:
  We study the QCD phase transition at finite temperature and discuss the
hadron bubble formation in the dual Ginzburg-Landau theory, which is an
effective theory of QCD and describes the color confinement via QCD-monopole
condensation. We formulate the effective potential at various temperatures and
find that thermal effects reduce the QCD-monopole condensate and bring a
first-order deconfinement phase transition. Based on this effective potential
at finite temperature, we investigate properties of hadron bubbles created in
the early Universe and discuss the hadron bubble formation process.


title:
Phase Transitions and Vacuum Tunneling Into Charge and Color Breaking
  Minima in the MSSM

abstract:
  The scalar potential of the MSSM may have local and global minima
characterized by non-zero expectation values of charged and colored bosons.
Even if the true vacuum is not color and charge conserving, the early Universe
is likely to occupy the minimum of the potential in which only the neutral
Higgs fields have non-zero vev's. The stability of this false vacuum with
respect to quantum tunneling imposes important constraints on the values of the
MSSM parameters. We analyze these constraints using some novel methods for
calculating the false vacuum decay rate. Some regions of the MSSM parameter
space are ruled out because the lifetime of the corresponding physically
acceptable false vacuum is small in comparison to the present age of the
Universe. However, there is a significant fraction of the parameter space that
is consistent with the hypothesis that the Universe rests in the false vacuum
that is stable on a cosmological time scale.


title: Higgs Boson Physics in the $s$-channel at $\mu^+\mu^-$ Colliders

abstract:
  Techniques and strategies for discovering and measuring the properties of
Higgs bosons via $s$-channel production at a $\mu^+\mu^-$ collider, and the
associated requirements for the machine and detector, are discussed in detail.
The unique feature of $s$-channel production is that, with good energy
resolution, the mass, total width and partial widths of a Higgs boson can be
directly measured with remarkable accuracy in most cases. For the expected
machine parameters and luminosity the Standard Model (SM) Higgs boson $\hsm$,
with mass $\lsim 2\mw$, the light $\hl$ of the minimal supersymmetric Standard
Model (MSSM), and the heavier MSSM Higgs bosons (the CP-odd $\ha$ and the
CP-even $\hh$) can all be studied in the $s$-channel, with the heavier states
accessible up to the maximal $\sqrt s$ over a large fraction of the MSSM
parameter space. In addition, it may be possible to discover the $\ha$ and
$\hh$ by running the collider at full energy and observing excess events in the
bremsstrahlung tail at lower energy. The integrated luminosity, beam resolution
and machine/detector features required to distinguish between the $\hsm$ and
$\hl$ are delineated.


title: High E_T jets at p \bar p collisions and triple gauge boson vertex

abstract:
  Triple gauge boson vertex, which is inherent to the model of a dynamical
breaking of the electroweak symmetry, leads to an effective four-fermion
interaction of quarks. Calculation of the effective coupling constant in the
framework of the model results in agreement with recent information on
enhancement of inclusive high E_T jet cross section at \sqrt{s} = 1.8 TeV. Thus
this effect may be connected with triple gauge boson vertex with coupling
constant \lambda \approx 0.7, which will clearly manifest itself at the soon
forthcoming LEP II.


title: The analytical value of the electron (g-2) at order alpha^3 in QED

abstract:
  We have evaluated in closed analytical form the contribution of the
three-loop non-planar `triple-cross' diagrams contributing to the electron
(g-2) in QED; its value, omitting the already known infrared divergent part, is
  a_e(3-cross) = 1/2 pi^2 Z(3) - 55/12 Z(5) - 16/135 pi^4
  + 32/3 (a4 + 1/24 ln(2)^4) + 14/9 pi^2 ln(2)^2
  - 1/3 Z(3) + 23/3 pi^2 ln(2) - 47/9 pi^2 - 113/48.
  This completes the analytical evaluation of the (g-2) at order alpha^3,
giving
  a_e(3-loop) = (alpha/pi)^3 { 83/72 pi^2 Z(3) - 215/24 Z(5)
  + 100/3 [( a4 + 1/24 ln(2)^4 ) - 1/24 pi^2 ln(2)^2 ]
  - 239/2160 pi^4 + 139/18 Z(3) - 298/9 pi^2 ln(2)
  + 17101/810 pi^2 + 28259/5184 } = (alpha/pi)^3 (1.181241456...).


title:
Inclusive One- and Two-Jet Cross sections in $\gamma\gamma$ Reactions at
  $e^+e^-$ Colliders

abstract:
  We have calculated inclusive one-- and two--jet production in photon--photon
collisions superimposing direct, single resolved and double resolved cross
sections for center of mass energies of the LEP1, LEP2 and NLC range. The
direct and single resolved cross sections are calculated up to
next--to--leading order. The double resolved two--jet cross section is
calculated only in LO with a $k$ factor estimated from the NLO one--jet cross
section. Various differential cross sections as functions of transverse momenta
and rapidities of the jets are evaluated.


title:
Confinement: Understanding the Relation Between the Wilson Loop and Dual
  Theories of Long Distance Yang Mills Theory

abstract:
  In this paper we express the velocity dependent, spin dependent heavy quark
potential $V_{q\bar q}$ in QCD in terms of a Wilson Loop $W(\Gamma)$ determined
by pure Yang Mills theory. We use an effective dual theory of long-distance
Yang Mills theory to calculate $W(\Gamma)$ for large loops; i.e. for loops of
size $R > R_{FT}$. ($R_{FT}$ is the flux tube radius, fixed by the value of the
Higgs (monopole) mass of the dual theory, which is a concrete realization of
the Mandelstam 't Hooft dual superconductor mechanism of confinement).
  We replace $W(\Gamma)$ by $W_{eff}(\Gamma)$, given by a functional integral
over the dual variables, which for $R > R_{FT}$ can be evaluated by a
semiclassical expansion, since the dual theory is weakly coupled at these
distances. The classical approximation gives the leading contribution to
$W_{eff}(\Gamma)$ and yields a velocity dependent heavy quark potential which
for large $R$ becomes linear in $R$, and which for small $R$ approaches lowest
order perturbative QCD. This latter fact means that these results should remain
applicable down to distances where radiative corrections giving rise to a
running coupling constant become important. The spin dependence of the
potential reflects the vector coupling of the quarks at long range as well as
at short range. The methods developed here should be applicable to any
realization of the dual superconductor mechanism. They give an expression
determining $W_{eff}(\Gamma)$ independent of the classical approximation, but
semi classical corrections due to fluctuations of the flux tube are not worked
out in this paper. Taking these into account should lead to an effective string
theory free from the conformal anomaly.


title: Diffractive Heavy Flavour Production at the Tevatron and the LHC

abstract:
  We give predictions for diffractive heavy flavour production at the Tevatron
and the LHC in leading--order approximation. In the framework of these studies
we use three different models for the partonic structure of the Pomeron
recently proposed by Stirling and Kunszt. These Pomeron models are, despite
being fitted to the same diffractive deep inelastic HERA data, very different
in their parton content and taken together provide a powerful tool to probe the
structure of the Pomeron. All models satisfy GLAP evolution and show a
significant $Q^2$ dependence. We give numerical predictions for single as well
as double diffractive cross sections assuming a Donnachie--Landshoff--type
Pomeron flux factor.


title: Charged Pion Polarizabilities to two Loops

abstract:
  We evaluate the electric and magnetic polarizabilities of charged pions in
the framework of chiral perturbation theory at next-to-leading order. This
requires a two-loop evaluation of the Compton amplitude near threshold. We
estimate the two new low-energy constants which enter the chiral expansion at
this order with resonance saturation. The numerical results are compared with
presently available experimental information.


title: F/D Ratios in Hyperon Beta Decays and Spin Distribution in the Nucleon

abstract:
  It is shown that hyperon beta decay data can be well accommodated within the
framework of Cabbibo's SU(3) symmetric description if one allows for a small
SU(3) symmetry breaking proportional to the mass difference between strange and
nonstrange quarks. The F/D ratio does not depend sensitively on the exact form
of the symmetry-breaking, and the best fits are close to the value previously
used in the analysis of deep inelastic scattering of electrons or muons on
polarized nucleons. The total quark helicity and strange quark polarization in
the nucleon are discussed.


title: Color-Octet $J/\psi$ Production in the $\Upsilon$ Decay

abstract:
  The direct production rate of $\psi$ in the $\Upsilon$ decay is shown to be
dominated by the process $ \Upsilon \to ggg^*$ followed by $g^* \to \psi$ via
the color-octet mechanism proposed recently to explain the anomalous prompt
charmonium production at the Tevatron. We show that this plausibly dominant
process has a branching ratio compatible with the experimental data. Further
experimental study in this channel is important to test the significance of the
color-octet component of $c\bar c$ pair inside the $\psi$ system.


title: New Gauge Bosons from String Models

abstract:
  We address the mass ranges of new neutral gauge bosons and constraints on the
accompanying exotic particles as predicted by a class of superstring models.
Under certain assumptions about the supersymmetry breaking parameters we show
that breaking of an additional U(1)' symmetry is radiative when the appropriate
Yukawa couplings of exotic particles are of order one, analogous to the
radiative breaking of the electro-weak symmetry in the supersymmetric standard
model due to the large top-quark Yukawa coupling. Such large Yukawa couplings
occur for a large class of string models. The Z' and exotic masses are either
of O(M_Z), or of a scale intermediate between the string and electro-weak
scales. In the former case, M_Z'=O(1 TeV) may be achievable without excessive
fine tuning, and is within future experimental reach. (This paper is a summary,
with a more phenomenological emphasis and additional discussion, of the results
in our earlier article "Implications of Abelian Extended Gauge Structures from
String Models", hep-ph/9511378.)


title:
Gauge Dependence of Four-Fermion QED Green Function and a Breakdown of
  Gauge Invariance in Atom-Like Bound State Calculations

abstract:
  We derive a relation between four-fermion QED Green functions of different
covariant gauges which defines the gauge dependence completely. We use the
derived gauge dependence to check the gauge invariance of atom-like bound state
calculations. We find that the existing QED procedure does not provide gauge
invariant binding energies. A way to a corrected gauge invariant procedure is
pointed out.


title: Comparative Study of $Z'$ Searches in $e^+e^-$ and $e^-e^-$ Scattering

abstract:
  We consider indirect searches for additional neutral vector bosons in
$e^+e^-$ and $e^-e^-$ collisions, and compare these two linear collider modes
with similar analysis procedures and assumptions. Discovery limits and
resolving power are discussed in a model independent way.


title: Symmetry Breaking and Collisions with $\sigma$-Mesons

abstract:
  In this brief report we adress spontaneous symmetry breaking in a
finite-temperature scalar meson plasma. We calculate the in-medium averaged
thermal $\sigma-\sigma$ scattering crossection and the related shear viscosity
$\eta(T)$ and mean-free-path $L(T)$. Our results suggest that slightly below
the critical temperature there is a 30 percent peak in the crossection leading
to equivalent dips in $\eta(T)$ and $L(T)$. We discuss the relevance of this
observation.


title: Photon Structure Function

abstract:
  After briefly explaining the idea of photon structure functions (\f2gam\ ,
\flgam) I review the current theoretical and experimental developements in the
subject of extraction of \qvph\ from a study of the Deep Inelastic Scattering
(DIS). I then end by pointing out recent progress in getting information about
the parton content of the photon from hard processes other than DIS.


title: Charged Pion-Pair Production and Pion Polarizabilities to two Loops

abstract:
  We evaluate the amplitude for gamma gamma --> pi^+ pi^- to two loops in the
framework of chiral perturbation theory.The three new coupling constants that
enter the result at this order in the low-energy expansion are estimated via
resonance saturation. We discuss in addition the crossed channel processes
gamma pi^+ --> gamma pi^+ - in particular the charged pion polarizabilities -
to the same accuracy. The predictions are compared with available experimental
information.


title: Higgs-mediated Slepton Pair-production at the Large Hadron Collider

abstract:
  At the LHC, directly pair-produced sleptons may be easier to identify than
those arising in cascade decays of squarks or gluinos. Higgs exchange processes
leading to such slepton pair-production are calculated to one-loop in the MSSM.
It turns out, surprisingly, that their total contribution can dominate the
usual Drell-Yan production in certain regions of the parameter space. In
particular, an interesting region with low $\tan \beta$ is covered by the
dominant exchange of the heavier neutral scalar $H^0$.


title:
Interferometry with Resonances and Flow in High-Energy Nuclear
  Collisions

abstract:
  The effects of resonances and flow on the correlation function for two
identical particles are described assuming chaotic sources and classical
propagation of particles. Expanding to second order in relative momenta, the
source sizes can be calculated directly and understood as contributions from
various fluctuations in the source. Specific calculations of source size radii
are given assuming Bjorken longitudinal flow with additional transverse
expansion. Results are compared to recent $\pi\pi$ and $KK$ correlation data
from relativistic nuclear collisions with particular attention to the reduction
in the $\pi\pi$ correlation function due to resonances and the decreasing
source sizes with increasing transverse momenta of the particles.


title:
Light Neutralinos as Dark Matter in the Unconstrained Minimal
  Supersymmetric Standard Model

abstract:
  The allowed parameter space for the lightest neutralino as the dark matter is
explored using the Minimal Supersymmetric Standard Model as the low-energy
effective theory without further theoretical constraints such as GUT. Selecting
values of the parameters which are in agreement with present experimental
limits and applying the additional requirement that the lightest neutralino be
in a cosmologically interesting range, we give limits on the neutralino mass
and composition. A similar analysis is also performed implementing the grand
unification constraints. The elastic scattering cross section of the selected
neutralinos on $^{27}$Al and on other materials for dark matter experiments is
discussed.


title: Supersymmetric Decays of the Top Quark: an update

abstract:
  We analyze the two decays $\thb$, $\tstn$ within the Minimal Supersymmetric
Standard Model with radiative breaking of the electroweak sector. We discuss
their detectability at present and in the eventuality that supersymmetry is not
discovered at LEPII.


title: Non-Linear Pomeron Trajectory in Diffractive Deep Inelastic Scattering

abstract:
  Recent experimental data on diffractive deep inelastic scattering collected
by the H1 and ZEUS Collaborations at HERA are analysed in a model with a
non-linear trajectory in the pomeron flux. The $t$ dependence of the
diffractive structure function $F_2^{D(4)}$ is predicted. The normalization of
the pomeron flux and the (weak) $Q^2$ dependence of the pomeron structure
function are revised as well.


title: An Effective Potential for Composite Operators

abstract:
  We study the effective potential for composite operators. Introducing a
source coupled to the composite operator, we define the effective potential by
a Legendre transformation. We find that in three or fewer dimensions, one can
use the conventionally defined renormalized operator to couple to the source.
However, in four dimensions, the effective potential for the conventional
renormalized composite operator is divergent. We overcome this difficulty by
adding additional counterterms to the operator and adjusting these order by
order in perturbation theory. These counterterms are found to be
non-polynomial. We find that, because of the extra counterterms, the composite
effective potential is gauge dependent. We display this gauge-dependence
explicitly at two-loop order.


title:
How reliably can the Higgs-Boson Mass be predicted from Electroweak
  Precision Data?

abstract:
  From the LEP precision data and the measurement of the W-boson mass, upon
excluding the observables Rb, Rc in a combined fit of the top-quark mass, Mt,
and the Higgs-boson mass, MH, within the Standard Model, we find the weak
1sigma bound of MH<900GeV. Stronger upper bounds on MH, sometimes presented in
the literature, rely heavily on the inclusion of Rb in the data sample. Upon
including Rb, the quality of the fit drastically decreases, and by carefully
analyzing the dependence of the fit results on the set of experimental input
data we conclude that these stronger bounds are not reliable. Moreover, the
stronger bounds on MH are lost if the deviation between theory and experiment
in Rb is ascribed to contributions of new physics. Replacing swbar^2(LEP) by
the combined value swbar^2(LEP+SLD) in the data sample leads to a bound of
MH<430GeV at the 1sigma level. The value of swbar^2(SLD) taken alone, however,
gives rise to fit results for MH which are in conflict with MH<65.2GeV from
direct searches.


title:
Spin Symmetry Without Heavy Quarks: Hyperon Form Factors In The Large
  $N_c$ Limit

abstract:
  In the large $N_c$ limit, all hyperon decays involving the same quark diagram
$Q\to Q'$ are described by a single weak form factor $\eta_{QQ'}(w)$. No
assumption on the mass of $Q$ or $Q'$ is necessary, making our results
applicable to both $b\to c$ and $c\to s$ transitions. This same form factor
describes both $\Lambda_Q\to\Lambda_{Q'}$ and
$\Sigma^{(*)}_Q\to\Sigma^{(*)}_{Q'}$ transitions. The (non-)commutativity
between the heavy quark and the large $N_c$ limits is briefly discussed under
the definite example of $\Lambda_b\to\Lambda_c$ decay.


title: R_b and New Physics: A Comprehensive Analysis

abstract:
  We survey the implications for new physics of the discrepancy between the LEP
measurement of $R_b$ and its Standard Model prediction. Two broad classes of
models are considered: ($i$) those in which new $Z\bbar b$ couplings arise at
tree level, through $Z$ or $b$-quark mixing with new particles, and ($ii$)
those in which new scalars and fermions alter the $Z \bbar b$ vertex at one
loop. We keep our analysis as general as possible in order to systematically
determine what kinds of features can produce corrections to $R_b$ of the right
sign and magnitude. We are able to identify several successful mechanisms,
which include most of those which have been recently been proposed in the
literature, as well as some earlier proposals (\eg\ supersymmetric models). By
seeing how such models appear as special cases of our general treatment we are
able to shed light on the reason for, and the robustness of, their ability to
explain $R_b$.


title:
Natural Unification with a Supersymmetric SO(10)$_{GUT} \:\times$
  SO(6)$_H$ Gauge Theory

abstract:
  We propose a unified model of elementary particles based on a supersymmetric
SO(10)$_{GUT} \:\times$ SO(6)$_H$ gauge theory. This model completely achieves
natural unification of the strong and electroweak interactions without any
fine-tunings.


title: Lorentz Boosts as Squeeze Transformations and the Parton Picture

abstract:
  It was shown by Gribov, Ioffe, Pomeranchuk in 1966 and by Ioffe in 1969 that
a space-time picture is needed for the Lorentz deformation of hadronic
interaction region. It is shown that this deformation is a squeeze
transformation. It is shown also that Feynman's parton picture emerges as a
consequence of Lorentz-squeezed hadrons in the quark model.


title: Nucleosynthesis and the mass of the tau neutrino

abstract:
  The primordial abundance of long-lived heavy Majorana neutrinos is calculated
from the full Boltzmann equation. Inclusion of scattering reactions drastically
change the predicted abundance of a heavy neutrino species. This loosens the
well known mass constraint on MeV neutrinos from Big Bang nucleosynthesis, and
allows for the existence of a Majorana tau neutrino with mass m > 11 MeV.
Further experimental efforts are therefore needed to investigate the range 11
MeV < m < 24 MeV. Some interesting cosmological consequences of an MeV nu_tau
are also pointed out.


title: Spectator Effects in Inclusive Decays of Beauty Hadrons

abstract:
  We present a model-independent study of spectator effects, which are
responsible for the lifetime differences between beauty hadrons. These effects
can be parametrized in terms of hadronic matrix elements of four four-quark
operators. For $B$ mesons, the coefficients of the non-factorizable operators
turn out to be much larger than those of the factorizable ones, limiting
considerably the usefulness of the vacuum insertion approximation.
Non-factorizable contributions to the lifetime ratio $\tau(B^-)/\tau(B_d)$
could naturally be of order 10--20%, and not even the sign of these
contributions can be predicted at present. In the case of the $\Lambda_b$
baryon, heavy-quark symmetry is used to reduce the number of independent matrix
elements from four to two. In order to explain the large deviation from unity
in the experimental result for $\tau(\Lambda_b)/\tau(B_d)$, it is necessary
that these baryon matrix elements be much larger than those estimated in quark
models. We have also reexamined the theoretical predictions for the
semileptonic branching ratio of $B$ mesons and charm counting, finding that,
given the present theoretical and experimental uncertainties, there is no
significant discrepancy with experiment.


title:
Hard gluon emission from colored scalar pairs\break in e^+ e^-
  annihilation

abstract:
  We study QCD correction to the pair production of colored scalar particles in
electron-positron annihilation with an emphasis on gluon emission in the final
state. We discuss the usefulness of working in a ``quasi-two-body'' frame and
present the helicity amplitudes for the process. We compare the final state
configuration with fermion pair production and find that the three-jet fraction
for the scalars shows quantitative difference from that for fermions.


title: Flavor Singlet Contribution to the Structure Function $g_1$ at Small-x

abstract:
  The singlet contribution to the $g_1(x,Q^2)$ structure function is calculated
in the double-logarithmic approximation of perturbative QCD in the region $x
\ll 1$. Double logarithmic contributions of the type $(\alpha_s \ln ^2
(1/x))^k$ which are not included in the GLAP evolution equations are shown to
give a power-like rise at small-x which is much stronger than the extrapolation
of the GLAP expressions. The dominant contribution is due to the gluons which,
in contrast to the unpolarized case, mix with the fermions also in the region
$x \ll 1$. The two main reasons why the small-x behavior of the double
logarithmic approximation is so much stronger than the usual GLAP evolution
are: the larger kinematical region of integration (in particular, no ordering
in transverse momentum) and the contributions from non-ladder diagrams.


title: Pair Production of Neutral Higgs Particles in Gluon--Gluon Collisions

abstract:
  Pair production processes of neutral Higgs particles will allow us to study
the trilinear Higgs couplings at future high--energy colliders. Several
mechanisms give rise to multi--Higgs final states in hadron interactions. In
the present paper we investigate Higgs pair production in gluon--gluon
collisions. After recapitulating pair production in the Standard Model, the
analysis of the cross sections is carried out in detail for the neutral Higgs
particles in the minimal supersymmetric extension.


title:
SUSY--QCD corrections to scalar quark pair production in $e^+ e^-$
  annihilation

abstract:
  We calculate the supersymmetric QCD corrections in order $\alpha_s$ to the
cross section $e^+ e^- \to \sq_i \bar\sq_j$ $(i,j = 1, 2)$ within the Minimal
Supersymmetric Standard Model. We pay particular attention to the case of the
left--right squark mixing and to the renormalization of the mixing angle. The
corrections due to gluino exchange turn out to be smaller than those due to
gluon exchange, but they can be significant at higher energies even for a
gluino mass of a few hundred GeV.


title:
Optimal observables for measuring three-gauge-boson couplings in $e^+
  e^- \to W^+ W^-$

abstract:
  Observables with optimised sensitivity to the $WWZ$ and $WW\gamma$-couplings
in $e^+ e^- \to W^+ W^-$ are investigated. They allow for separate studies of
CP violation and of absorptive parts in the amplitude. We have calculated
expected statistical errors on extracted couplings at $\sqrt{s} = 500 GeV$,
with unpolarised or longitudinally polarised beams.


title:
Electroweak Baryon Number Non-Conservation in the Early Universe and in
  High Energy Collisions

abstract:
  We review recent progress in the study of the anomalous baryon number
non-conservation at high temperatures and in high energy collisions. Recent
results on high temperature phase transitions are described, and applications
to electroweak baryogenesis are considered. The current status of the problem
of electroweak instanton-like processes at high energies is outlined. This
paper is written on the occasion of Sakharov's 75th anniversary and will appear
in the memorial volume of Uspekhi (Usp. Fiz. Nauk, volume 166, No 5, May 1996).


title:
Multiple Parton Emission Effects in Next-to-Leading Order Direct Photon
  Production

abstract:
  A recent global analysis of direct photon production at hadron collider and
fixed target experiments has noted a disturbing trend of disagreement between
next-to-leading-order (NLO) calculations and data. The conjecture has been made
that the discrepancy is due to explicit multiple parton emission effects which
are not accounted for in the theoretical calculations. We investigate this
problem by merging a NLO calculation of direct photon production with extra
multiple parton emissions via the parton shower (PS) algorithm. Our calculation
maintains the integrity of the underlying NLO calculation while avoiding
ambiguities due to double counting of multiple parton emissions. We find that
the NLO+PS calculation can account for much of the theory/CDF data discrepancy
at $\sqrt{s}=1.8$ TeV. It can also account for much of the theory/UA2
discrepancy if a very large virtuality is assumed to initiate the initial state
parton shower. For lower energy data sets ({\it e.g.} $\sqrt{s}< 63$ GeV),
NLO+PS calculations alone cannot account for the data/theory discrepancy, so
that some additional non-perturbative $k_T$ smearing is needed.


title:
$R_b$ and $R_c$ in the Two Higgs Doublet Model with Flavor Changing
  Neutral Currents

abstract:
  A study of $R_b$ and $R_c$ is presented in the context of a Two Higgs Doublet
Model (2HDM) with flavor changing scalar currents (FCSC). Implications of the
model for the $\rho$-parameter and for $b\to s\gamma$ are also considered. The
experimental data on $R_b$ places stringent constraints on the model
parameters. The configuration of the model needed to account for $R_b$ is found
to be irreconcilable with constraints from $b\to s\gamma$ and $\rho$. In
particular, if $R^{\rm exp}_b>R^{\sss{\rm SM}}_b$ persists then this version of
2HDM will be ruled out or require significant modifications. Noting that
aspects of the experimental analysis for $R_b$ and $R_c$ may be of some
concern, we also disregard $R^{\rm exp}_b$ and $R^{\rm exp}_c$ and give
predictions for these using constraints from $b\to s\gamma$ and $\rho$
parameter only. We emphasize the theoretical and experimental advantages of the
observable $R_{b+c}\equiv \Gamma(Z\to b\bar b\mbox{ or } c\bar
c)/\Gamma(Z\to\mbox{hadrons})$. We also stress the role of $R_\ell\equiv
\Gamma(Z\to\mbox{hadrons})/\Gamma(Z\to \ell^+\ell^-)$ in testing the Standard
Model (SM) despite its dependence on QCD corrections. Noting that in models
with FCNC the amplitude for $Z\to c\bar c$ receives a contribution which grows
with $m^2_t$, the importance and uniqueness of precision $Z\to c\bar c$
measurements for constraining flavor changing $t\bar c$ currents is
underscored.


title:
Discrepancy-based error estimates for Quasi-Monte Carlo. II: Results in
  one dimension

abstract:
  The choice of a point set, to be used in numerical integration, determines,
to a large extent, the error estimate of the integral. Point sets can be
characterized by their discrepancy, which is a measure of its non-uniformity.
Point sets with a discrepancy that is low with respect to the expected value
for truly random point sets, are generally thought to be desirable. A low value
of the discrepancy implies a negative correlation between the points, which may
be usefully employed to improve the error estimate of a numerical integral
based on the point set. We apply the formalism developed in a previous
publication to compute this correlation for one-dimensional point sets, using a
few different definitions of discrepancy.


title: Leptophobic U(1)'s and the R_b - R_c Crisis

abstract:
  In this paper, we investigate the possibility of explaining both the R_b
excess and the R_c deficit reported by the LEP experiments through Z-Z' mixing
effects. We have constructed a set of models consistent with a restrictive set
of principles: unification of the Standard Model (SM) gauge couplings, vector-
like additional matter, and couplings which are both generation-independent and
leptophobic. These models are anomaly-free, perturbative up to the GUT scale,
and contain realistic mass spectra. Out of this class of models, we find three
explicit realizations which fit the LEP data to a far better extent than the
unmodified SM or MSSM and satisfy all other phenomenological constraints which
we have investigated. One realization, the \eta-model coming from E_6, is
particularly attractive, arising naturally from geometrical compactifications
of heterotic string theory. This conclusion depends crucially on the inclusion
of a U(1) kinetic mixing term, whose value is correctly predicted by
renormalization group running in the E_6 model given one discrete choice of
spectra.


title: New Leptoquark Mechanism of Neutrinoless Double Beta Decay

abstract:
  A new mechanism for neutrinoless double beta ($\znbb$) decay based on
leptoquark exchange is discussed. Due to the specific helicity structure of the
effective four-fermion interaction this contribution is strongly enhanced
compared to the well-known mass mechanism of $\znbb$ decay. As a result the
corresponding leptoquark parameters are severely constrained from
non-observation of $\znbb$-decay. These constraints are more stringent than
those derived from other experiments.


title: Nucleon Structure and High Energy Scattering

abstract:
  If the pomeron is generated by a two gluon exchange there is no a priori
reason for a drastic suppression of three gluon exchange with negative parity
and charge parity. This would lead to an unacceptably large difference between
$p\,p$ and $p\, \bar{p}$ scattering. It is shown that a natural suppression of
the $C$=$P$=--1 contribution to high energy scattering is given by a cluster
structure of the nucleon.


title:
Applicability of Heavy Quark Effective Theory to the Radiative Decay
  $B\to K^* + \gamma$

abstract:
  In the context of the observed decay $B \rightarrow K^* \gamma$ the
applicability of the Heavy Quark Effective Theory (HQET), treating both b and s
as heavy quarks, is examined. We show that the heavy s-quark approximation, as
can be found in the literature, is not reliable.


title: Quantisation of Global Isospin in the Skyrme Crystal

abstract:
  A quantisation of chiral symmetry within the Skyrme crystal is carried out.
The definition of global isospin in the crystal is explored, and found to be
ambiguous. However, the state corresponding to a neutron crystal is identified,
and the leading quantum correction to the classical mass is computed. The
results are compared to those of Klebanov for a crystal of whole skyrmions.


title: Relaxation and Kinetics in Scalar Field Theories

abstract:
  A new approach to the dynamics of relaxation and kinetics of thermalization
in a scalar field theory is presented that incorporates the relevant time
scales through the resummation of hard thermal loops. An alternative derivation
of the kinetic equations for the ``quasiparticle'' distribution functions is
obtained that allows a clear understanding of the different ``coarse graining''
approximations usually involved in a kinetic description. This method leads to
a systematic perturbative expansion to obtain the kinetic equations including
hard-thermal loop resummation and to an improvement including renormalization,
off-shell effects and contributions that change chemical equilibrium on short
time scales. As a byproduct of these methods we establish the relation between
the relaxation time scale in the linearized equation of motion of the
quasiparticles and the thermalization time scale of the quasiparticle
distribution function in the ``relaxation time approximation''. Hard thermal
loop resummation dramatically modifies the scattering rate for long wavelength
modes as compared to the usual (semi) classical estimate. Relaxation and
kinetics are studied both in the unbroken and broken symmetry phases of the
theory. The broken symmetry phase also provides the setting to obtain the
contribution to the kinetic equations from processes that involve decay of a
heavy scalar into light scalar particles in the medium.


title: On the odderon intercept in perturbative QCD

abstract:
  Arguments are presented for the odderon intercept being exactly equal to
unity. A variational method is presented based on a complete system of
one-gluon functions. For the odderon, the highest intercept calculated by this
method is $1-(3\alpha_{s}/\pi)\,0.45$.


title:
Like Sign Dilepton Signature for R-Parity Violating SUSY Search at the
  Tevatron Collider

abstract:
  The like sign dileptons provide the most promising signature for
superparticle search in a large category of $R$-parity violating SUSY models.
We estimate the like sign dilepton signals at the Tevatron collider, predicted
by these models, over a wide region of the MSSM parameter space. One expects an
unambiguous signal upto a gluino mass of $200 - 300$ GeV ($\geq 500$ GeV) with
the present (proposed) accumulated luminosity of $\sim 0.1~(1)~{\rm fb}^{-1}$.


title: Anomalous Couplings and Chiral Lagrangians: An Update

abstract:
  We present an update of the limits expected for anomalous gauge boson
couplings in the language of chiral Lagrangian operators at the LHC and the
Linear Collider. Both, the $e^+e^-$ and the $\gamma\gamma$ mode of the Linear
Collider are analyzed. With a 500~GeV $e^+e^-$ collider, and an integrated
luminosity of 50~--~80~fb$^{-1}$, one reaches the domain of precision
measurements.


title: Decoupling or nondecoupling: is that the $R_b$ question?

abstract:
  The top quark is well known for the nondecoupling effects it implies in
$\rho$ and $R_b$. The recent experimental $R_b$ data exhibits a disagreement
with the SM prediction at more than the $3 \sigma$ level. It is tempting to
explore whether this might be due to nondecoupling New Physics effects,
opposite to those of the top. We investigate this issue in the context of
models with an extra family of right or left handed, singlet or doublet quarks.
It is shown that, contrary to what one might naively expect, the nondecoupling
properties of a mirror $t^\prime$ do not have an impact on $R_b$, due to a
conspiracy of the mixing angles, imposed by the requirement that there be no
$b$ - $b^\prime$ mixing. Our analysis agrees with an analysis performed
independently, which includes this model as a particular case.


title:
Lepton-Flavor Violating Decays of the $Z$-boson in a Left-Right
  Supersymmetric Model

abstract:
  We study the one-loop supersymmetric contributions to lepton-flavor violating
$Z$ -boson decays in a fully left-right symmetric model. In addition to
right-handed scalar neutrinos, the decays could receive important contributions
from doubly-charged triplet Higgsinos which couple to leptons only. We find
that the decay widths reach present experimental bounds and discuss mass
constraints for the contributing supersymmetric partners.


title: CP Phases in Models with Some Fermion Masses Vanishing and/or Degenerate

abstract:
  We count the number of CP breaking phases in models with $SU(2)_L\times
U(1)_Y$ and $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ electroweak gauge groups
and extended matter contents with some fermion masses vanishing and/or
degenerate. Quarks and leptons, including Majorana neutrinos, are treated in a
similar way. CP violation is characterized in the mass-eigenstate and in the
weak-eigenstate bases. Necessary and sufficient conditions for CP conservation,
invariant under weak basis redefinitions are also studied in these models. CP
violating factors entering in physical observables and only invariant under
phase redefinitions are discussed.


title:
Spontaneous annihilation of high-density matter in the electroweak
  theory

abstract:
  In the presence of fermionic matter the topologically distinct vacua of the
standard model are metastable and can decay by tunneling through the sphaleron
barrier. This process annihilates one fermion per doublet due to the anomalous
non-conservation of baryon and lepton currents and is accompanied by a
production of gauge and Higgs bosons. We present a numerical method to obtain
local bounce solutions which minimize the Euclidean action in the space of all
configurations connecting two adjacent topological sectors. These solutions
determine the decay rate and the configuration of the fields after the
tunneling. We also follow the real time evolution of this configuration and
analyze the spectrum of the created bosons. If the matter density exceeds some
critical value, the exponentially suppressed tunneling triggers off an
avalanche producing an enormous amount of bosons.


title: $R_b$-$R_c$ Crisis and the Higgs Boson Mass from LEP Precision Data

abstract:
  We study the effects on the Higgs boson mass from LEP precision data of the
new physics explaining $R_b$-$R_c$ crisis. We implement a fit to LEP
observables with the new physics. We obtain $M_H^{\rm New Physics} = 85 ^{+
467}_{-56} ~~{\rm GeV}$. Comparing with the value of the SM fit, $M_H^{\rm SM}
= 38^{+ 96}_{-21} ~~{\rm GeV}$, the errors are larger and the central value is
higher. The new physics may allow $M_H$ to have a value out of the range of
${\cal O}(M_Z)$.


title: A covariant diquark-quark model of the nucleon in the Salpeter approach

abstract:
  We develop a rather simple, formally covariant quark-diquark model of the
nucleon. The nucleon is treated as a bound state of a constituent quark and a
diquark interacting via a quark exchange. We include both scalar and
axial-vector diquarks. The underlying Bethe-Salpeter equation is transformed
into a pair of coupled Salpeter equations. The electromagnetic form factors of
the nucleon are calculated in the Mandelstam formalism. We obtain a very good
description of all electromagnetic form factors for momentum transfers up to -3
(GeV/c)^2.


title: Standard Model stability bounds for new physics within LHC reach

abstract:
  We analyse the stability lower bounds on the Standard Model Higgs mass by
carefully controlling the scale independence of the effective potential. We
include resummed leading and next-to-leading-log corrections, and physical pole
masses for the Higgs boson, M_H, and the top-quark, M_t. Particular attention
is devoted to the cases where the scale of new physics \Lambda is within LHC
reach, i.e. \Lambda\leq 10 TeV, which have been the object of recent
controversial results. We clarify the origin of discrepancies and confirm our
earlier results within the error of our previous estimate. In particular for
\Lambda=1 TeV we find that
  M_H[GeV]>52+0.64(M_t[GeV]-175)-0.50\frac{\alpha_s(M_Z)-0.118}{0.006}.
  For fixed values of M_t and \alpha_s(M_Z), the error from higher effects, as
the lack of exact scale invariance of the effective potential and higher-order
radiative corrections, is conservatively estimated to be \simlt 5 GeV.


title: How Can Strange Quark Matter Occur Deeply in the Atmosphere?

abstract:
  Motivated by some recent cosmic ray experiments we study the properties of
strange quark matter near flavour equilibrium. Using Fermi-gas model we argue
that, contrary to some claims, the geometrical radii of quark matter
strangelets are not smaller but rather comparable to those of ordinary nuclei.
We propose therefore a scenario of propagation of strangelets through the
atmosphere which still allows for their deep penetration.


title: Colour: A Computer Program for QCD Colour Factor Calculations

abstract:
  A computer program for evaluating colour factors of QCD Feynman diagrams is
presented, and illustrative examples on how to use the program to calculate non
trivial colour factors are given. The program and the discussion in this paper
is based on a diagrammatic approach to colour factors.


title: A model for $F_L$ and $R={F_L/F_T}$ at low $x$ and low $Q^2$

abstract:
  A model for the longitudinal structure function $F_L$ at low $x$ and low
$Q^2$ is presented, which includes the kinematical constraint $F_L \sim Q^4$ as
$Q^2 \rightarrow 0$. It is based on the photon-gluon fusion mechanism suitably
extrapolated to the region of low $Q^2$. The contribution of quarks having
limited transverse momentum is treated phenomenologically assuming that it is
described by the soft pomeron exchange mechanism. The ratio
$R={F_L/(F_2-F_L)}$, with the $F_2$ appropriately extrapolated to the region of
low $Q^2$, is also discussed.


title: $F_L$ at low $x$ and low $Q^2$

abstract:
  A model for the longitudinal structure function $F_L$ in the region of low
$x$ and low $Q^2$ is discussed. It is constructed using the $k_T$ factorization
theorem and a photon-gluon fusion mechanism suitably extrapolated to the region
of low $Q^2$. A phenomenological model for higher twist is presented, which is
based on the assumption that the contribution of quarks having limited
transverse momenta is dominated by the soft pomeron exchange mechanism.