title: Multi-Majoron Modes for Neutrinoless Double-Beta Decay

abstract:
  We construct two new classes of models for double beta decay, each of which
leads to an electron spectrum which differs from the decays which are usually
considered. One of the classes has a spectrum which has not been considered to
date, and which is softer than the usual two-neutrino decay of the Standard
Model. We construct illustrative models to show how other phenomenological
bounds can be accommodated. We typically find that, although all other bounds
can be satisfied, the predicted double-beta decay rate only in one class of
these models is at best large enough to be just detectable in current
experiments.


title: QCD Sum Rules For Pion Wave Function Revisited

abstract:
  We analyze new QCD sum rules for the pion wave function $\phi_{\pi}(x)$,
obtained recently by A.V. Radyushkin in the framework of the non-local vacuum
condensates method for non-diagonal correlators, and suggest a new approach for
extracting wave functions of the $\pi$-meson and of its first resonances. As a
result we obtain approximately the same form of the pion wave function by using
two different methods and for two different ansatzes of non-local quark
condensates. We predict the mass of the $\pi'$-resonance and obtain the form of
its wave function. The first method uses integrated (in a sense) properties of
ansatzes and may be considered as an alternative to traditional borel SR.


title:
Models of Fermion Mass Matrices Based on a Flavor- and
  Generation-Dependent U(1) Gauge Symmetry

abstract:
  We study models of fermion mass matrices based on a flavor- and
generation-dependent string-motivated U(1)$_A$ gauge symmetry and report two
new classes of solutions to the requisite consistency conditions. In
particular, we propose that the fundamental reason underlying the striking
feature $m_b, \ m_\tau << m_t$ is that all of the elements of the down-quark
and charged lepton effective Yukawa matrices actually arise from
higher-dimension operators, suppressed by inverse powers of the Plank mass. An
explicit model embodying this idea is constructed.


title: Electroweak Physics at LEP

abstract:
  We have examined the evidence for the electroweak radiative corrections in
the LEP precision data sets of 1993 and 1994 along with the intriguing
possibility that the QED corrections only may be sufficient to fit the data
within the framework of the minimal standard model. We find that the situation
is very sensitive to the precise values of $M_W$. The current world average
value of $M_W$ and the improved 1994 LEP data strongly favor nonvanishing
electroweak radiative corrections and are consistent with a heavy $m_t$ as
reported by CDF but with a heavy Higgs scalar of about 400 GeV. We discuss how
future precision measurements of $M_W$ and $m_t$ can provide a decisive test
for the standard model with radiative corrections.


title: Nonperturbative Evaluation of the Sphaleron Transition Rate

abstract:
  We review nonperturbative calculations of the rate of sphaleron transitions
on the lattice in $1+1$-dimensional field theories and introduce a way to
perform the gauge-invariant Gibbs averages in the classical non-Abelian Higgs
theories.


title: Top Quark Signature in Extended Color Theories

abstract:
  We consider the implications of an extended color group, $SU\left( 3\right)
_I\times SU\left( 3\right) _{II}$, spontaneously broken to $SU\left( 3\right)
_c$ at a TeV or lower scale, for the hadronic colliders. The associated massive
color octet gauge bosons (the colorons) can enhance the $t \overline{t}$ pair
production at the Tevatron collider. At the LHC, the colorons can be pair
produced, each decaying to a $t\overline{t}$ pair. This gives rise to anomalous
multi W production: a clear signature of physics beyond the Standard Model. We
calculate the associated multijet and multilepton final states at the Tevatron
and the LHC energies, and compare these with the expectations from the Standard
Model.


title:
${\bar p} p$ Annihilation: Manifestations of Instanton Induced Quark
  Pair Production ?

abstract:
  Production of strangeness in the low-energy ${\bar p} p$ annihilation is
analyzed as a manifestation of the instanton induced multiquark vertex.
Approach based on the {\it qualitative} properties of the 't Hooft mechanism
provides a unified description of available experimental data on $K$- and
$\phi$-meson production. Crucial tests for the hypothesized mechanism are
suggested.


title: Solving SUSY GUT Problems: Gauge Hierarchy and Fermion Masses

abstract:
  The supersymmetric $SU(6)$ model accompanied by the flavour-blind discrete
symmetry $Z_3$ can succesfully deal with such key problems of SUSY GUTs, as are
the gauge hierarchy/doublet-triplet splitting, $\mu$-problem and flavour
problem. The Higgs doublets arise as Goldstone modes of the spontaneously
broken {\em accidental} global $SU(6)\times U(6)$ symmetry of the Higgs
superpotential. Their couplings to fermions have peculiarities leading to the
consistent picture of the quark and lepton masses and mixing, without invoking
any of horizontal symmetry/zero texture concepts. In particular, the only
particle that has direct Yukawa coupling with the Higgs doublet is top quark.
Other fermion masses appear from the higher order operators, with natural mass
hierarchy. Specific mass formulas are also obtained. [On the basis of talks
given at the Int. Workshop "Physics from Planck Scale to Electroweak Scale",
Warsaw, Poland, 21-24 September 1994, and at the III Trieste Conference "Recent
Developments in the Phenomenology of Particle Physics", Trieste, Italy, 3-7
October 1994.]


title:
From Effective Lagrangians, to Chiral Bags, to Skyrmions with the
  Large-N_c Renormalization Group

abstract:
  We explicitly relate effective meson-baryon Lagrangian models, chiral bags,
and Skyrmions in the following way. First, effective Lagrangians are
constructed in a manner consistent with an underlying large-N_c QCD. An
infinite set of graphs dress the bare Yukawa couplings at *leading* order in
1/N_c, and are summed using semiclassical techniques. What emerges is a picture
of the large-N_c baryon reminiscent of the chiral bag: hedgehog pions for r >
1/\Lambda patched onto bare nucleon degrees of freedom for r < 1/\Lambda, where
the ``bag radius'' 1/\Lambda is the UV cutoff on the graphs. Next, a novel
renormalization group (RG) is derived, in which the bare Yukawa couplings,
baryon masses and hyperfine baryon mass splittings run with \Lambda. Finally,
this RG flow is shown to act as a *filter* on the renormalized Lagrangian
parameters: when they are fine-tuned to obey Skyrme-model relations the
continuum limit \Lambda --> \infty exists and is, in fact, a Skyrme model;
otherwise there is no continuum limit.


title:
Polarization of $\tau$ lepton from scalar tau decay as a probe of
  neutralino mixing

abstract:
  The $\tau$ lepton arising from the scalar tau ($\st$) decay is naturally
polarized. $\ptau$ depends on the left--right mixing of the $\st$ and the
gaugino--higgsino mixing of the neutralino. The polarization $\ptau$ could be
measured from the energy distribution of the decay products of $\tau$ at future
$\epem$ colliders. A measurement of $\ptau$and of the $\st$ production cross
section allows to determine both these mixing angles.


title: Evanescent Operators, Scheme Dependences and Double Insertions

abstract:
  The anomalous dimension matrix of dimensionally regularized four-quark
operators is known to be affected by evanescent operators, which vanish in
$D=4$ dimensions. Their definition, however, is not unique, as one can always
redefine them by adding a term proportional to $(D-4)$ times a physical
operator. In the present paper we compare different definitions used in the
literature and find that they correspond to different renormalization schemes
in the physical operator basis. The scheme transformation formulae for the
Wilson coefficients and the anomalous dimension matrix are derived in the
next-to-leading order. We further investigate the proper treatment of
evanescent operators in processes appearing at second order in the effective
four-fermion interaction such as particle-antiparticle mixing, rare hadron
decays or inclusive decays.


title: Measuring~~$|V_{ub}|$~~at~~the~~LEP/SLC

abstract:
  We show that the observation of energetic charged leptons from semileptonic
$B$-meson decays at the LEP and SLC $Z$--boson factories offers a unique
opportunity to measure the quark mixing matrix element $|V_{ub}|$. We present
various distributions of the $B$ decay products to show that the $b \to u$
decays can be cleanly separated from the $b \to c$ decays, with a signal of
$O(100)$ events per million $Z$ bosons produced.


title:
Fermi motion parameter $p_{_F}$ of $B$ meson from relativistic quark
  model

abstract:
  The Fermi motion parameter $p_{_F}$ is the most important parameter of ACCMM
model, and the value $p_{_F} \sim 0.3$ GeV has been used without clear
theoretical or experimental evidence. So, we attempted to calculate the value
for $p_{_F}$ theoretically in the relativistic quark model using quantum
mechanical variational method. We obtained $p_{_F} \sim 0.5$ GeV, which is
somewhat larger than 0.3 GeV, and we also derived the eigenvalue of $E_B \simeq
5.5$ GeV, which is in reasonable agreement with $m_B=5.28$ GeV. We also
recalculated $|V_{ub}/V_{cb}|$ as a function of $p_{_F}$.


title:
Four-Quark States and Nucleon-Antinucleon Annihilation within the Quark
  Model with Instanton Induced Interaction

abstract:
  The spectrum of $q^2\bar q^2, J^p=0^+,2^+$ mesons is discussed. We have shown
that due to instanton - induced forces the physical states are strong mixtures
of the $SU_f(3)$ group basis states. The cross-sections for annihilation of the
$N\bar N$ system into $(q^2\bar q^2)(q\bar q)$ mesons are obtained. The
$a_0(980)$ meson is considered as $q^2\bar q^2$ meson consisting of $9_f$ and
$36_f$ plets. The branchings are also predicted for the cross-sections for
production of the $a_0(980)$ and tensor $q^2\bar q^2$ mesons in $N\bar N$
annihilation.


title:
Constraints on the Minimal SUSY SO(10) Model from Cosmology and the
  $b\to s \gamma$ Decay

abstract:
  It is shown that the minimal supersymmetric SO(10) model with electroweak
radiative breaking and universal soft mass terms at the GUT scale is strongly
disfavoured by the combination of constraints from the $b\to s \gamma$ decay
and the condition $\Omega h^2 < 1$ for the lightest (stable) neutralino. The
constraints are, however, easily satisfied for certain class of supersymmetric
SO(10) models with non--universal scalar masses which gives small
supersymmetric corrections to the bottom quark mass and light higgsino--like
neutralinos.


title: Two-loop electroweak top corrections: are they under control?

abstract:
  The assumption that two-loop top corrections are well approximated by the
$O(G_mu^2 mt^4)$ contribution is investigated. It is shown that in the case of
the ratio neutral-to-charged current amplitudes at zero momentum transfer the
$O(G_mu^2 mt^2 M_Z^2)$ terms are numerically comparable to the $m_t^4$
contribution for realistic values of the top mass. An estimate of the
theoretical error due to unknown two-loop top effect is presented for a few
observables of LEP interest.


title: Two Gluon Exchange Model Predictions for Double Pomeron Jet Production

abstract:
  I extend the two gluon exchange picture of elastic scattering, known as the
Low-Nussinov or Subtractive Quark Model, to predict cross sections for double
pomeron exchange processes. In particular, I calculate p p-bar to p p-bar q
q-bar where the q q-bar partons appear as jets separated from the final p and
p-bar by large gaps in rapidity. The predicted cross section is large enough
that this process should be observable at the Fermilab Tevatron and at the
Large Hadron Collider. It can be distinguished from the background of ordinary
jet production by the absence of particles produced in the gap regions.


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

abstract:
  We calculate the QCD radiative corrections to the production of
supersymmetric scalar partners of quarks in e+e- annihilation. We include both
the standard gluonic corrections and the genuine supersymmetric QCD corrections
due to quark--gluino loops, and allow for mixing between left-- and
right--handed scalar quarks which leads to the possibility that the two final
state particles have different masses. The corrections are found to be much
larger than the ones affecting the production of spin 1/2 particles.


title:
Selection Rule for Generation Numbers and Gauge Anomalies for
  Unification Groups

abstract:
  The possibilities of global (non-perturbative) gauge anomalies for a class of
gauge groups are investigated. Intimately connected to branching rules and
topological aspect of gauge groups, the results are applied to the study of
unification gauge groups such as SO(10), SU(5), $E_6$, $E_8$ etc. Especially,
we discuss extensively about the selection rule for generation numbers
$N_f+N_{mf}=even\ge 4$ in SO(10) and supersymmetric SO(10) unification theories
as originally proposed by the author$^1$, where $N_f$ and $N_{mf}$ denote the
generation numbers for ordinary fermions and mirror fermions respectively. This
is due to the global gauge anomalies from some subgroups of SO(10) in a
fundamental spinor representation such that the ill-defined 'large' gauge
transformations in the subgroup cannot be unwrapped in SO(10) in the quantum
theory as we noted$^1$. A similar result related to left-right symmetric models
is also given.


title: Angular structure of QCD jets

abstract:
  We derive the angular correlation functions between an arbitary number of
partons inside a quark or gluon jet emerging from a high energy hard collision.
As an application results for the correlation in the relative angle between two
partons as well as the multiplicity moments of any order for partons in a
sidewise angular region are calculated. At asymptotic energies the
distributions of rescaled angular variables approach a scaling limit of a new
type with two redundant quantities. All observables reveal the power behaviour
characteristic to the fully developed selfsimilar cascade in appropriate
regions of phase space. We present analytical results from the double
logarithmic approximation as well as Monte Carlo results.


title: Yukawa Textures and Anomalies

abstract:
  We augment the Minimal Supersymmetric Standard Model with a gauged
family-dependent $U(1)$ to reproduce Yukawa textures compatible with
experiment. In the simplest model with one extra chiral electroweak singlet
field, acceptable textures require this $U(1)$ to be anomalous. The
cancellation of its anomalies by a generic Green-Schwarz mechanism requires
$\sin^2\theta_w=3/8$ at the string scale, suggesting a superstring origin for
the standard model.


title: A survey of phenomenological constraints on supergravity models

abstract:
  We advocate the study of supergravity models as well motivated few-parameter
low-energy supersymmetric models. In this context we survey a broad range of
phenomenological constraints and future tests, including present and
near-future Tevatron ($\tilde q,\tilde g,\chi^\pm_1,\tilde t_1$) and LEP
($h,\chi^\pm_1$) mass limits, collider indirect tests ($\Gamma_Z^{\rm
inv},R_b,m_t$), rare processes ($b\to s\gamma,(g-2)_\mu$), proton decay, and
dark matter (cosmology, direct and indirect detection).


title: Superstrings:The View from Below

abstract:
  We review the Standard Model in a form conducive to formulating its possible
short distance extensions. This depends on the value of the Higgs mass, the
only unknown parameter of the model. We suggest methods to reproduce many of
the small numbers in the model in terms of scale ratios, applying see-saw like
ideas to the breaking of chiral symmetries. We then investigate how the $N=1$
Standard Model extrapolated to or near the Planck scale can fit superstring
models, emphasizing the use of some non-renormalizable operators generic to
superstrings.


title: The Concept of Potential in Quantum Field Theory

abstract:
  In quantum field theory the concept of a Lagrangian interaction density,
expressed in terms of fields, is primary. Forces between two particles are
regarded as arising primarily from the exchange of quanta of the bosonic
fields. Thus, in contrast to nonrelativistic quantum mechanics, the concept of
a two-body poten tial is secondary. Potentials are not given a priori but must
be defined. Part of the purpose of this talk is to review and discuss the
issues involved when such definitions are made. In this context I describe a
gauge-independent approach to some aspects of the problem of determining the
energy levels of bound states, developed in collaboration with the late G.
Feinberg, and report some recent results on the long-range potential associated
with two-photon exchange between charged particles.


title: Interference Rate of Radiation of 2 Charges in Circular Motion

abstract:
  We present an exact formula for the computation of the interference rate of
radiation in the case of two charges revolving with constant angular velocity
at opposite ends of a diameter in a fixed circle. The formula is valid for
arbitrary velocities of the charges, and can be easily studied by numerical
methods, even for velocities very close to the velocity of light. For
ultrarelativistic motion, the interference rate of radiation behaves as
$\ln(1-v^2/c^2)^{-1/2}$, which contrasts with the behavior $(1 - v^2/c^2)^{-2}$
for the rate of radiation for one charge in circular motion. This is the first
exact calculation for the interference rate of radiation of two relativistic
charges, and it is useful in connection with the old controversy about the
correctness of the Lorentz-Dirac equations of motion for more than one charge.


title: Perspective on Quark Mass and Mixing Relations

abstract:
  Recent data indicate that $V_{ub}\cong \lambda^4 \cong (0.22)^4$, while $m_t$
seems to be $174$ GeV. The relations $m_d/m_s\sim m_s/m_b \sim \delta \sim
\lambda^2 \simeq \vert V_{cb}\vert$ and $m_u/m_c\sim m_c/m_t \sim \delta^2 \sim
\lambda^4 \sim \vert V_{ub}\vert$ suggest that %a plausible clean separation of
the %origin of the quark mixing matrix: the down type sector is responsible for
$\vert V_{us}\vert$ and $\vert V_{cb}\vert$, while $V_{ub}$ comes from the up
type sector. Five to six parameters might suffice to account for the ten quark
mass and mixing parameters, resulting in specific power series representations
for the mass matrices. In this picture, $\delta$ seems to be the more sensible
expansion parameter, while $\lambda \cong \sqrt{m_d/m_s} \sim \sqrt{\delta}$ is
tied empirically to $(M_d)_{11} = 0$.


title:
Violation of the Energy Conservation Law in Lorentz-Dirac Equations for
  More Than One Charge

abstract:
  An exact solution of Lorentz-Dirac equations where the energy conservation
law is violated, is described herein for the case of two charges.


title: The $\pi\pi$ scattering amplitude in chiral perturbation theory

abstract:
  We discuss $\pi\pi$ scattering in the framework of chiral perturbation
theory. In particular, we recall the predictions made some time ago for the
threshold parameters and for the phase shift difference
$\delta_0^0-\delta_1^1$.


title:
CP asymmetry Relations Between $\bar B^0\rightarrow \pi\pi$ and $\bar
  B^0\rightarrow \pi K$ Rates

abstract:
  We prove that CP violating rate difference $\Delta (\bar B^0 \rightarrow
\pi^+\pi^-) = \Gamma (\bar B^0 \rightarrow \pi^+\pi^-) - \Gamma ( B^0
\rightarrow \pi^-\pi^+)$ is related to $\Delta (\bar B^0 \rightarrow \pi^+ K^-)
= \Gamma (\bar B^0 \rightarrow \pi^+K^-) - \Gamma (B^0 \rightarrow \pi^-K^+)$
in the three generation Standard Model. Neglecting small annihilation diagrams,
and in the SU(3) symmetry limit, we show $\Delta (\bar B^0 \rightarrow
\pi^+\pi^-) = - \Delta (\bar B^0 \rightarrow \pi^+ K^-)$. The SU(3) breaking
effects are estimated using factorization approximation, and yield $\Delta
(\bar B^0\rightarrow \pi^+\pi^-) \approx -(f_\pi/f_K)^2\Delta (\bar B^0
\rightarrow \pi^+K^-)$. Usefulness of this remarkable relation for determining
phases in the CKM unitarity triangle is discussed.


title: Heavy Quark Effective Theory on the Light Front

abstract:
  The light-front heavy quark effective theory is derived to all orders in
$1/m_Q$. In the limit $m_Q\rightarrow \infty$, the theory exhibits the familiar
heavy quark spin-flavor symmetry. This new formalism permits a straightforward
canonical quantization to all orders in $1/m_Q$; moreover, higher order terms
have rather simple operator structures. The light-front heavy quark effective
theory can serve as an useful framework for the study of non-perturbative QCD
dynamics of heavy hadron bound states.


title: Hyperintermittency ?

abstract:
  The analogy between the intermittency and scaling in statistical physics is
extended to the case of more variables. It is shown that the inclusive
densities predicted by the perturbative QCD obey generalized homogeneity
principle which leads to many consequences in statistical physics. In
particular the hyperscaling may be a prototype for the hyperintermittency in
multiparticle production at high energies.


title: Field Theoretic Description of High Energy Neutrino Interactions

abstract:
  In this paper we begin the development of a formalism for the description of
high energy neutrino interactions. It is based upon field theory quantized on a
null plane.
  We set up the general formalism as well as some techniques needed to perform
phenomenological calculations. We show that the formalism developed by
Wolfenstein is recovered at the cost of making two approximations: one has to
treat the charged lepton fields in the Hartree--Fock approximation and one has
to take the short distance limit of the Hartree--Fock correlation function. As
an example, we discuss the resonant interaction of electron neutrinos in an
electron gas.


title:
Phenomenology of Soft Terms in the Presence of Nonvanishing Hidden
  Sector Potential Energy

abstract:
  We argue that the hidden sector potential energy is generically of order the
intermediate scale although the true cosmological constant does vanish. This
would significantly change the predicted values of soft parameters for a
variety of supergravity models including those derived from string theory. We
stress that this point is particularly relevant for supergravity models in
which the soft masses of observable fields vanish at tree level. Implications
of a nonzero hidden sector potential energy for low energy phenomenology are
also studied.


title:
A Closer Look at Perturbative Corrections in the b->c Semileptonic
  Transitions

abstract:
  We comment on two recent calculations of the second order perturbative
corrections in the heavy flavor semileptonic transitions within the
Brodsky-Lepage-Mackenzie approach. It is pointed out that the results do not
show significant enhancement either in the inclusive $b\rightarrow c$ decays or
in the exclusive amplitudes at zero recoil provided that the expansion
parameter is chosen in a way appropriate to the kinematics at hand. The values
of the second-order coefficients inferred from the BLM-type calculations appear
to be of order unity in the both cases. Thus, in both cases no significant
uncertainty in extracting $V_{cb}$ can be attributed to perturbative effects.
The theoretical accuracy is mostly determined by the existing uncertainty in
$1/m_c^2$ nonperturbative corrections in the exclusive $B\rightarrow D^*$
amplitude, and, to a lesser extent, by the uncertainty in the estimated value
of the kinetic energy matrix element $\mu_\pi^2$ in the case of $\Gamma_{\rm
sl}(b\rightarrow c)$. The theoretical accuracy of the inclusive method of
determination of $V_{cb}$ seemingly competes with and even exceeds the
experimental accuracy.


title:
Boundary and Coulomb Effects on Boson Systems in High-Energy Heavy-Ion
  Collisions

abstract:
  The boundary of a boson system plays an important role in determining the
momentum distribution of the bosons. For a boson system with a cylindrical
boundary, the momentum distribution is enhanced at high transverse momenta but
suppressed at low transverse momenta, relative to a Bose-Einstein distribution.
The boundary effects on systems of massless gluons and massive pions are
studied. For gluons in a quark-gluon plasma, the presence of the boundary may
modify the signals for the quark-gluon plasma. For pions in a pion system in
heavy-ion collisions, Coulomb final-state interactions with the nuclear
participants in the vicinity of the central rapidity region further modify the
momentum distribution at low transverse momenta. By including both the boundary
effect and the Coulomb final-state interactions we are able to account for the
behavior of the $\pi^{-}$ transverse momentum spectrum observed in many
heavy-ion experiments, notably at low transverse momenta.


title:
Simple one-dimensional integral representations for two-loop
  self-energies: the master diagram

abstract:
  The scalar two-loop self-energy master diagram is studied in the case of
arbitrary masses. Analytical results in terms of Lauricella- and
Appell-functions are presented for the imaginary part. By using the dispersion
relation a one-dimensional integral representation is derived. This
representation uses only elementary functions and is thus well suited for a
numerical calculation of the master diagram.


title: Probing transverse quark polarization in deep-inelastic leptoproduction

abstract:
  The azimuthal dependence of hadrons produced in lepton scattering off a
polarized hadron probes the quark transverse-spin distributions. In the
calculation of the asymmetries, transverse momenta of quarks in the
distribution and fragmentation functions must be incorporated. In addition to
the $\sin (\phi + \phi_S)$ asymmetry for transversely polarized hadrons, known
as the Collins effect, we find $\sin 2\phi$ asymmetries for both transversely
and longitudinally polarized hadrons.


title: High temperature QCD and QED with unstable excitations

abstract:
  We consider the partition functions of QCD and QED at high temperature
assuming small coupling constants, and present arguments in favor of an
improved perturbative expansion in terms of unstable excitations. Our effective
propagators are derived from spectral functions with a constant width. These
spectral functions describe screening and damping of gluons (photons) as well
as ``Brownian'' motion of quarks (electrons). BRST-invariance allows us to
reduce the number of independent width parameters to three. These are
determined in a self-consistent way from the one-loop self energy and
polarization tensor in the infrared limit thus rendering this limit finite. All
spectral width parameters are found to be proportional to $g T$. We reproduce
the well known expression for the electric ``Debye''-screening mass. The
transverse (magnetic) gluons (photons) are found to interact only at nonzero
momentum or energy, at least to leading order. As a consequence their spectral
function acquires a width only away from the infrared limit. Finally, plasmon
modes are determined and found to be strongly damped.


title: How does the BFKL-Pomeron couple to quarks ?

abstract:
  We investigate the coupling of the BFKL-Pomeron to quarks and to colorless
states. Special emphasis is given to the effective quark-quark scattering
amplitude of Mueller and Tang.


title:
Upper bound on the supersymmetry breaking scale in supersymmetric SU(5)
  model.

abstract:
  The status of coupling constant unification in standard supersymmetric SU(5)
model and its extensions is discussed. Taking into account uncertainties
related with the initial coupling constants and threshold corrections at low
and high scales we find that in supersymmetric SU(5) model the scale of
supersymmetry breaking could be up to $10^8$ Gev. In the extensions of standard
SU(5) model it is possible to increase the supersymmetry breaking scale up to
$10^{11}$ Gev.


title: Confining Bethe--Salpeter equation from scalar QCD

abstract:
  We give a nonperturbative derivation of the Bethe--Salpeter equation based on
the Feynman--Schwinger path integral representation of the one--particle
propagator in an external field. We apply the method to the quark--antiquark
system in scalar QCD and obtain a confining BS equation assuming the Wilson
area law in the straight line approximation. The result is strictly related to
the relativistic flux tube model and to the $q \bar{q}$ semirelativistic
potential.


title:
Density of strings formed at a second-order cosmological phase
  transition

abstract:
  We discuss the problem of estimating the characteristic length scale
$\xi_{\rm s}$, and hence the initial density, of a system of cosmic strings
formed at a continuous, second-order phase transition in the early universe. In
particular, we examine the roles of the correlation length (or string width)
$\xi_{\rm c}$ and the Ginzburg length $\xi_{\rm G}$ which defines the
``fuzziness'' of long strings. We argue that strings acquire a clear identity
only once $\xi_{\rm s}$ exceeds both $\xi_{\rm c}$ and $\xi_{\rm G}$, and
estimate its magnitude at that time.


title: QCD EQUATIONS FOR GENERATING FUNCTIONALS AND MULTIPARTICLE CORRELATIONS

abstract:
  QCD equations for generating functionals are solved at coinciding momenta of
particles. As a result, the relations for $q$-particle correlation functions at
equal momenta are obtained. They are directly connected to previously derived
results about the factorial and cumulant moments of multiplicity distributions.
It is predicted that the correlations at coinciding points decrease, first, as
a function of the rank $q$, and then start oscillating when represented in a
form of the ratio of cumulant to factorial correlations. In particular, the
cumulant function of the fifth rank should become negative at the origin. Some
experimental data are discussed.


title: Scenarios And Signals Of Very Heavy Neutrinos

abstract:
  Preliminary remarks, theoretical scenarios, cosmological constraints,
couplings of very heavy neutrinos, production mechanisms and detection,
summary.


title: Isospin correlations in high-energy heavy-ion collisions

abstract:
  We study the posibility of large isospin fluctuations in high-energy
heavy-ion collisions by assuming that pions are produced semiclassically both
directly and in pairs through the isovector channel. The leading-particle
effect and the factorization property of the scattering amplitude in the impact
parameter space are used to define the classical pion field. In terms of the
joint probability function $P_{II_{3}}(n_{0},n_{\_})$ for producing $n_{0}$
neutral and $n_{\_}$ negative pions from a definite isospin state $II_{3}$ of
the incoming leading-particle system we calculate the two pion correlation
parameters $f_{2,n_{\_}}^{0}$ and the average number of neutral pions $(< n_{0}
>_{n_{\_}})$ as a function of negative pions $(n_{\_})$ produced. We show that
only direct production of pions without isovector pairs leads to large isospin
fluctuations.


title:
CP/CPT Experiments with Neutral Kaons -OR- Experimental Study of Two
  Complex Numbers eta+- and eta00

abstract:
  Recent and upcoming Fermilab experiments to probe the origin of CP violation
and to search for CPT violation are reviewed for an audience of theoretical
particle physics graduate students.


title:
Non-Universal Correction To $Z \to b {\bar{b}}$ And Flavor Changing
  Neutral Current Couplings

abstract:
  A non-universal interaction associated with top quark induces flavor changing
neutral currents (FCNC) among light fermions. The size of the FCNC effect
depends crucially on the dynamics of the fermion mass generation. In this
paper, we study the effect of a non-universal interaction on $Z b b$, $Z b s$
{\it etc}, by using an effective lagrangian technique and assuming the quark
mass matrices in the form of a generalized Fritzsch ansatz. We point out that
if fitting $R_b$ to the LEP data within $1 \sigma$, the induced FCNC couplings
are very close to the experimental limits.


title: Baryons as Chiral Solitons in the Nambu--Jona-Lasinio Model

abstract:
  The description of baryons as chiral solitons of the Nambu--Jona--Lasinio
(NJL) model is reviewed. A motivation for the soliton description of baryons is
provided from large $N_C$ QCD. Rigorous results on the spontaneous breaking of
chiral symmetry in QCD are discussed. It is then argued that the NJL model
provides a fair description of low--energy hadron physics. The NJL model is
therefore employed to mimic the low--energy chiral flavor dynamics of QCD. The
model is bosonized by functional integral techniques and the physical content
of the emerging effective meson theory is discussed. In particular, its
relation to the Skyrme model is established. The static soliton solutions of
the bosonized NJL model are found, their properties discussed, and the
influence of various meson fields studied. These considerations provide strong
support of Witten's conjecture that baryons can be understood as soliton
solutions of effective meson theories. The chiral soliton of the NJL model is
then quantized in a semiclassical fashion and various static properties of the
nucleon are studied. The dominating $1/N_C$ corrections to the semiclassically
quantized soliton are investigated. Time--dependent meson fluctuations off the
chiral soliton are explored and employed to estimate the quantum corrections to
the soliton mass. Finally, hyperons are described as chiral solitons of the NJL
model. This is done in both, the collective rotational approach of Yabu and
Ando as well as in the bound state approach of Callan and Klebanov.


title: COULOMB EFFECTS IN W+ W- PRODUCTION

abstract:
  We calculate the Coulomb effects on the cross section for e+ e- --> W+ W-
taking into account the instability of the W bosons. We carefully explain the
consequences of instability throughout the energy range which will be
accessible at LEP2. We present a formula which allows these effects to be
easily implemented.


title: The line shape of the $Z$ boson

abstract:
  At LEP~1, cross sections and cross section asymmetries may be analysed model
independently. Cross sections depend on four, asymmetries on two free
parameters. As an example, I discuss the model independent $Z$ boson mass
determination from the $Z$ line shape and compare it to the Standard Model
approach.


title: Supersonic Deflagrations in Cosmological Phase Transitions

abstract:
  The classification of the hydrodynamical growth mechanisms for the spherical
bubbles of the low-temperature phase in cosmological phase transitions is
completed by showing that the bubbles can grow as supersonic deflagrations.
Such deflagrations consist of a Jouguet deflagration, followed by a rarefaction
wave. Depending on the amount of supercooling, the maximal velocity of
supersonic deflagrations varies between the sound and the light velocities. The
solutions faster than supersonic deflagrations are weak detonations.


title:
$\eta -\eta^\prime$ Photoproduction and the Axial Isoscalar Neutral
  Current Coupling

abstract:
  We show that coherent $\eta$ and $\etap$ photoproduction by means of the
Primakoff Effect on the proton depends on the strange component of the neutral
axial current coupling. We construct polarization asymmetries that are
sensitive to this coupling through the $\gamma - Z$ interference. The
$\eta^\prime$ is not a Goldstone boson of a spontaneously broken chiral
symmetry, but a phenomenological analysis of the $\eta$ and $\eta^\prime$
production through chiral perturbation theory allows to calculate the
observables of interest. The polarized proton or polarized photon asymmetries
are predicted to be close to
  $10^{-4}$ for $-q^2 \sim 0.1-0.5\;\mbox{\rm GeV}^2$.


title: Enhancement of top production in $e^+ e^- \to t\bar t$

abstract:
  We investigate $e^+ e^- \to t\bar t$ by taking into account wave function
distortion effects in the near-threshold region and interpolating the
correction factor to the high-energy perturbative QCD region. The strong color
attraction between the color singlet $t$ and $\bar t$ enhances the cross
section over the tree level results near threshold. The rise of the cross
section near the threshold is smoothed by the effects of the large top width
and below-threshold resonances. The reliability of the prediction is well
assessed by comparing with experimental $R$ ratios for lighter quark production
at lower energies. The cross sections obtained here using the reported values
of the top mass, can be used directly for New Linear Collider (NLC)
projections.


title: What Can Be Learned with an Iodine Solar-Neutrino Detector?

abstract:
  We study the potential benefits of an iodine-based solar-neutrino detector
for testing hypotheses that involve neutrino oscillations. We argue that such a
detector will have a good chance of distinguishing the two allowed regions of
$\Delta m^2$ -- $\sin^22\theta$ parameter space if neutrino conversion is
occurring in the sun. It should also be able to detect seasonal variations in
the signal due to vacuum oscillations and might be sensitive enough to detect
day/night variations due to MSW transitions in the earth. Although it would
need to be calibrated, a working iodine detector could be completed before more
ambitious projects that seek to accomplish the same things.


title: REALISTIC MODELS WITH A LIGHT U(1) GAUGE BOSON COUPLED TO BARYON NUMBER

abstract:
  We recently showed that a new gauge boson $\gamma_B$ coupling only to baryon
number is phenomenologically allowed, even if $m_B<m_Z$ and $\alpha_B \approx
0.2$. In our previous work we assumed that kinetic mixing between the baryon
number and hypercharge gauge bosons (via an $F^{\mu\nu}_B F_{\mu\nu}^Y$ term)
was small enough to evade constraints from precision electroweak measurements.
In this paper we propose a class of models in which this term is naturally
absent above the electroweak scale. We show that the generation of a mixing
term through radiative corrections in the low-energy effective theory does not
lead to conflict with precision electroweak measurements and may provide a
leptonic signal for models of this type at an upgraded Tevatron.


title:
Nonfactorization and Color-Suppressed $B \to \psi (\psi(2S))+K(K^*)$
  Decays

abstract:
  Using $N_c=3$ value of the parameter $a_2=0.09$ but including a modest
nonfactorized amplitude, we show that it is possible to understand all data,
including polarization, for color-suppressed $B\to\psi(\psi(2S))+K(K^*) $
decays in all commonly used models of form factors. We show that for $B\to\psi
+K$ decay one can define an effective $ a_2$, which is process-dependent and,
in general, complex; but it is not possible to define an effective $a_2$ for
$B\to\psi +K^* $ decay. We also explain why nonfactorized amplitudes do not
play a significant role in color-favored B decays.


title:
Determining $\alpha_s$ from Measurements at $Z$: How Nature Prompts us
  about New Physics

abstract:
  The value of $\alpha_s (M_Z)$ emerging from the so called global fits based
mainly on the data at the $Z$ peak (and assuming the standard model) is three
standard deviations higher than the one stemming from the low-energy
phenomenology. The corresponding value of $\Lambda_{\rm QCD}$ is very large,
$\sim$ 500 MeV, and is incompatible with crucial features of QCD. If persists,
the discrepancy should be interpreted as due to contributions to the
$Z$-quark-antiquark vertices which go beyond the standard model.


title:
Thermal Two Point Function of a Heavy Muon in hot QED plasma within
  Bloch Nordsieck Approximation

abstract:
  The thermal propagator of a heavy muon propagating in a hot QED plasma is
examined within the Bloch-Nordsieck approximation, which is valid in the
infrared region. It is shown that the muon damping rate is finite, in contrast
to the lower-order calculation with hard thermal loop resummations taken into
account.


title: A Comment on the Experimental Determination of $|V_{ts}/V_{td}|^2$.

abstract:
  We propose a method to extract the ratio $|V_{ts}/V_{td}|^2$ from a
measurement of $\Delta \Gamma/\Gamma$ for the $B_s$ meson. This method is
experimentally more sensitive than the conventional method for large values of
$|V_{ts}|$ but depends on the accuracy of parton level calculations.


title: Glueball plus Pion Production in Photon-Photon Collisions.

abstract:
  We here compute the reaction $ \gamma \; \gamma \rightarrow G \; \pi^{0} $
for various glueball candidates $ G $ and their assumed quantum states, using a
non-relativistic gluon bound-state model for the glueball.


abstract:
  We calculate the decay rate for inclusive $B \rightarrow {\tau}{\nu}X$ decays
in a two Higgs doublet model using heavy quark expansion and operator product
expansion. Combined with the recent measurement of Br($B \ra \tau \nu X$), we
find a limit $\tan \beta < 0.58 m_H/\mbox{GeV}$ at 90\%\ C.L..


title:
HOW TO LIMIT RADIATIVE CORRECTIONS TO THE COSMOLOGICAL CONSTANT BY
  M^4_Susy

abstract:
  Supergravity models are constructed in which the effective low energy theory
contains only ``super-soft'' explicit supersymmetry breaking: masses of the
scalars and pseudoscalars within a multiplet are split in opposite directions.
With this form of supersymmetry breaking the radiative corrections of the
matter sector to the vacuum energy are bounded by ${\cal O} (M^4_{Susy})$ to
all orders in perturbation theory, and we require $Str M^2 = 0$ including the
hidden sector. The models are based on K\"ahler potentials obtained in recent
orbifold compactifications, and we describe the construction of realistic
theories.


title: Charginos and Neutralinos at LEPII

abstract:
  We show that LEPII will either discover charginos and neutralinos, or enable
a very stringent upper limit to be placed on $\tan \beta$ as a function of the
gluino mass. The only assumption we make is the existence of some unified model
which breaks down to the minimal supersymmetric standard model below the
unification scale. In such a framework we discuss how the discovery of a
chargino at LEPII and the measurement of its mass and production cross-section,
together with the measurement of the mass of the lightest neutralino, would
enable the gluino mass, $\tan \beta$ and $\mu$ to be predicted, up to a
possible ambiguity in the sign of $\mu$ which we discuss.


title: On the Gluon Plasmon Self-Energy at O(g)

abstract:
  The next-to-leading order contribution $\d\P\omn (\o ,\vc q )$ to the
polarization function of the hot gluon system is analysed at non-zero wave
vectors $\vc q \,$. Using Braaten-Pisarski resummation and general covariant
gauges, $\d\P\omn$ is found to be gauge-fixing independent and transverse on
the longitudinal mass-shell. The real part of the longitudinal component
$\d\P_\ell$ is UV and IR stable (for real $q$). At imaginary $q$ it is IR
singular, and at the point $\o=0$, $q^2=-3m^2$ it coincides with the result of
Rebhan for next-to-leading order Debye screening. When $q$ approaches the
lightcone, $\d\P_\ell $ diverges like $1 / \wu {\o^2 - q^2} $, reflecting the
breakdown of the Braaten-Pisarski decomposition scheme in this limit.


title: A GLOBAL QCD STUDY OF DIRECT PHOTON PRODUCTION

abstract:
  A global QCD analysis of the direct photon production process from both fixed
target and collider experiments is presented. These data sets now completely
cover the parton $x$ range from 0.01 to 0.6, thereby providing a stringent test
of perturbative QCD and parton distributions. Previous detailed studies of
direct photons emphasized fixed target data. We find most data sets have a
steeper $p_t$ distribution than the QCD prediction. Neither global fits with
new parton distributions nor improved photon fragmentation functions can
resolve this problem since the deviation occurs at different $x$ values for
experiments at different energies. A more likely explanation is the need for
additional broadening of the $k_t$ of the initial state partons. The magnitude
and the possible physical origin of this effect are investigated and discussed.


title: Summation of Leading Logarithms at Small x

abstract:
  We show how perturbation theory may be reorganized to give splitting
functions which include order by order convergent sums of all leading
logarithms of $x$. This gives a leading twist evolution equation for parton
distributions which sums all leading logarithms of $x$ and $Q^2$, allowing
stable perturbative evolution down to arbitrarily small values of $x$.
Perturbative evolution then generates the double scaling rise of $F_2$ observed
at HERA, while in the formal limit $x\to 0$ at fixed $Q^2$ the Lipatov
$x^{-\lambda}$ behaviour is eventually reproduced. We are thus able to explain
why leading order perturbation theory works so well in the HERA region.


title: Bethe Ansatz for QCD Pomeron,

abstract:
  The equivalence is found between high-energy QCD in the generalized leading
logarithmic approximation and the one-dimensional Heisenberg magnet. According
to Regge theory, the high energy asymptotics of hadronic scattering amplitudes
are related to singularities of partial waves in the complex angular momentum
plane. In QCD, the partial waves are determined by nontrivial two-dimensional
dynamics of the transverse gluonic degrees of freedom. The "bare" gluons
interact with each other to form a collective excitation, the Reggeon. The
partial waves of the scattering amplitude satisfy the Bethe-Salpeter equation
whose solutions describe the color singlet compound states of Reggeons --
Pomeron, Odderon and higher Reggeon states. We show that the QCD Hamiltonian
for reggeized gluons coincides in the multi-color limit with the Hamiltonian of
XXX Heisenberg magnet for spin s=0 and spin operators the generators of the
conformal SL(2,C) group. As a result, the Schrodinger equation for the compound
states of Reggeons has a sufficient number of conservation laws to be
completely integrable. A generalized Bethe ansatz is developed for the
diagonalization of the QCD Hamiltonian and for the calculation of hadron-hadron
scattering. Using the Bethe Ansatz solution of high-energy QCD we investigate
the properties of the Reggeon compound states which govern the Regge behavior
of the total hadron-hadron cross sections and the small-x behavior of the
structure functions of deep inelastic scattering.


title: New Symmetries of Supersymmetric Effective Lagrangians

abstract:
  We consider the structure of effective lagrangians describing the low-energy
dynamics of supersymmetric theories in which a global symmetry $G$ is
spontaneously broken to a subgroup $H$ while supersymmetry is unbroken. In
accordance with the supersymmetric Goldstone theorem, these lagrangians contain
Nambu--Goldstone superfields associated with a coset space $G^c / \hat{H}$,
where $G^c$ is the complexification of $G$ and $\hat{H}$ is the largest
subgroup of $G^c$ that leaves the order parameter invariant. The lagrangian may
also contain additional light matter fields. To analyze the effective
lagrangian for the matter fields, we first consider the case where the
effective lagrangian is obtained by integrating out heavy modes at weak
coupling (but including non-perturbative effects such as instantons). We show
that the superpotential of the matter fields is $\hat{H}$ invariant, which can
give rise to non-trivial relations among independent $H$-invariants in the
superpotential. We also show that the Kahler potential of the matter fields can
be restricted by a remnant of $\hat{H}$ symmetry. These results are
non-perturbative and have a simple group-theoretic interpretation. When we
relax the weak-coupling constraint, there appear to be additional possibilities
for the action of $\hat{H}$ on the matter fields, hinting that the constraints
imposed by $\hat{H}$ may be even richer in strongly coupled theories.


title: TIME EVOLUTION OF $K^0-\bar{K^0}$ SYSTEM IN SPECTRAL FORMULATION

abstract:
  We reanalyse the time evolution of the $K^0-\bar{K^0}$ system in the language
of certain spectral function whose Fourier transforms give the time dependent
survival and transition amplitudes. The reanalysis turned out to be necessary
in view of the astonishing theorem by Khalfin on the possibility of vacuum
regeneration of $K_S$ and $K_L$. The main reason for this unexpected behaviour
is the non-orthogonality of $\ks$ and $\kl$. As a result of this theorem new
contributions to the well known oscillatory terms will enter the time dependent
transition probabilities. These new terms are not associated with small/large
time behaviour of the amplitudes and therefore their magnitude is apriori
unknown. Approximating the spectral functions by an one-pole ansatz Khalfin
estimated the new effect in transition probabilities to be $4 \times 10^{-4}$.
Whereas we agree with Khalfin on the general existence of vacuum regeneration
of $K_S$ and $K_L$ we disagree on the size of the effect. A careful analysis of
the one-pole approximation reveals that the effect is eleven orders of
magnitude smaller than Khalfin's estimate and, in principle, its exact
determination lies outside the scope of the one-pole ansatz. The present paper
gives also insight into the limitation of the validity of one-pole
approximation, not only for small/large time scales, but also for intermediate
times where new effects, albeit small, are possible. It will be shown that the
same validity restrictions apply to the known formulae of Weisskopf-Wigner
approximation as well.


title: Structure of Light

abstract:
  In this talk I briefly explain the concept of the structure function of a
photon (the best known boson). Then I review some of the current experimental
evidence which confirms the existence of `strong' interactions of photon
suggested by this idea. I end by pointing out how the photon `structure' has
important implications for the interactions of high energy photons and hence
for the design of the next generation of the high energy $e^+e^-$ (linear)
colliders which are absolutely essential for locating the missing links in our
knowledge of fundamental particles and interactions among them.


title:
Majorana neutrino versus Dirac neutrino in ${\rm e}^{+}{\rm e}^{-} \to
  {\rm W}^{+}{\rm W}^{-}$ through radiative corrections

abstract:
  Radiative corrections to ${\rm e}^{+}{\rm e}^{-}\! \rightarrow {\rm
W}^{+}{\rm W}^{-}$ from Majorana neutrinos are studied in the context of the
see-saw mechanism. Focusing on the effects of the fourth generation neutrinos,
we calculate W-pair form factors, the differential cross sections and the
forward-backward asymmetries for the polarized electrons at one-loop level. The
behaviour of the form factors at the threshold of Majorana particle pair
productions is found to differ from that of Dirac particle pair productions. In
the cross section for unpolarized electrons, the radiative corrections,
depending on the mass parameters of the see-saw mechanism, are found to be
$\sim 0.5\%$ at the energy range of the LEP200 and the next generation linear
colliders.


title: TESTING THE $WW\gamma$ COUPLING AT $e^+e^-$ COLLIDERS

abstract:
  The production of single photons plus missing energy at future $e^{+}e^{-}$
colliders can provide a testing ground for non-standard $WW\gamma$ couplings.
We show that even with conservative estimates of systematic errors there is
still considerable sensitivity to anomalous couplings.


title: Correlations and strong interactions

abstract:
  It is argued that correlations and multiplicity distributions constitute one
of the most characteristic properties of strong interactions. The progress made
in the last years in our understanding of correlations is reviewed.


title: Effective Field Theories for Hadrons and Nuclei

abstract:
  Hadron structure and nuclear structure are discussed from the common ground
of effective chiral Lagrangians modeling QCD at low energy. The topics treated
are the chiral bag model in large $N_c$ QCD, its connection to heavy-baryon
chiral perturbation theory (HB\chpt),\ the role of nonabelian Berry gauge
connections for baryon excitations and the application of HB\chpt \ to the
thermal $n+p\rightarrow d +\gamma$ process and to the axial-charge transitions
in heavy nuclei.


title:
A Study of Ultraviolet Renormalon Ambiguities in the Determination of
  $\as$ from $\tau$ Decay

abstract:
  The divergent large-order behaviour of the perturbative series relevant for
the determination of $\as$ from $\tau$ decay is controlled by the leading
ultraviolet (UV) renormalon. Even in the absence of the first infrared (IR)
renormalon, an ambiguity of order $\Lambda^2/m_\tau^2$ is introduced. We make a
quantitative study of the practical implications of this ambiguity. We discuss
the magnitude of UV renormalon corrections obtained in the large-$N_f$ limit,
which, although unrealistic, is nevertheless interesting to some extent. We
then study a number of improved approximants for the perturbative series, based
on a change of variable in the Borel representation, such as to displace the
leading UV renormalon singularity at a larger distance from the origin than the
first IR renormalon. The spread of the resulting values of $\as(m^2_\tau)$
obtained by different approximants, at different renormalization scales, is
exhibited as a measure of the underlying ambiguities. Finally, on the basis of
mathematical models, we discuss the prospects of an actual improvement, given
the signs and magnitudes of the computed coefficients, the size of
$\as(m^2_\tau)$ and what is known of the asymptotic properties of the series.
Our conclusion is that a realistic estimate of the theoretical error cannot go
below $\delta\as(m^2_\tau) \sim \pm 0.060$, or $\delta\as(m^2_{\sss Z}) \sim
\pm 0.006$.


title: A MODEL INDEPENDENT APPROACH TO FUTURE SOLAR NEUTRINO EXPERIMENTS

abstract:
  It is shown that from the data of future solar neutrino experiments (SNO and
Super-Kamiokande), in which high-energy $^8\mathrm{B}$ neutrinos will be
detected, it will be possible in a model independent way: 1) To reveal the
presence of sterile neutrinos in the flux of solar neutrinos on the earth; 2)
To obtain the initial flux of $^8\mathrm{B}$ $\nu_e$'s; 3) To determine the
probability of $\nu_e$'s to survive as a function of neutrino energy.


title: Scale Ratios in the Standard Model

abstract:
  We review the present knowledge of the Standard Model that is relevant in
formulating its possible short distance extensions. We present different
scenarios in terms of the Higgs mass, the only unknown parameter of the model.
We concentrate on the many small numbers in the model and suggest generic
methods to reproduce these numbers in terms of scale ratios, applying see-saw
like ideas to the breaking of chiral symmetries.


title: Probing for the Roots of the Standard Model

abstract:
  The differences between the $N=0$ and $N=1$ standard models are emphasized in
formulating their short distance extension. We sketch methods to reproduce many
of the small numbers in the model in terms of scale ratios, applying see-saw
like ideas to the breaking of chiral symmetries. We sketch how the $N=1$
standard model, outfitted with an extra family Abelian symmetry to reproduce
the mass hierarchies, naturally fits superstring models, by making use of
generic non-renormalizable operators.


title: Raising the unification scale in supersymmetry

abstract:
  In the minimal supersymmetric standard model, the three gauge couplings
appear to unify at a mass scale near $2 \times 10^{16}$ GeV. We investigate the
possibility that intermediate scale particle thresholds modify the running
couplings so as to increase the unification scale. By requiring consistency of
this scenario, we derive some constraints on the particle content and locations
of the intermediate thresholds. There are remarkably few acceptable solutions
with a single cleanly defined intermediate scale far below the unification
scale.


title: Instantons and Meson Correlators in QCD

abstract:
  Various QCD correlators are calculated in the instanton liquid model in
zeromode approximation and $1/N_c$ expansion. Previous works are extended by
including dynamical quark loops. In contrast to the original "perturbative"
$1/N_c$ expansion not all quark loops are suppressed. In the flavor singlet
meson correlators a chain of quark bubbles survives the $N_c\to\infty$ limit
causing a massive $\eta^\prime$ in the pseudoscalar correlator while keeping
massless pions in the triplet correlator. The correlators are plotted and meson
masses and couplings are obtained from a spectral fit. They are compared to the
values obtained from numerical studies of the instanton liquid and to
experimental results.


title:
Nonfactorization and the decays $D_s^+ \to \phi \pi^+, \phi \rho^+$ and
  $\phi l^+ \nu_l$

abstract:
  In six chosen scenarios for the $q^2$ dependence of the form factors involved
in $D_s^+ \rightarrow \phi $ transition, we have determined the allowed domain
of $x = A_2(0) / A_1(0)$ and $y = V(0)/A_1(0)$ from the experimentally measured
ratios $R_{sl} = \Gamma(D_s^+ \rightarrow \phi l^+ \nu_l)/\Gamma(D_s^+
\rightarrow \phi \pi^+)$ and $R_h = \Gamma(D_s^+ \rightarrow \phi
\rho^+)/\Gamma(D_s^+ \rightarrow \phi \pi^+)$ in a scheme that uses the $N_c
=3$ value of the phenomenological parameter $a_1$ and includes nonfactorized
contribution. We find that the experimentally measured values of $x$ and $y$
from semileptonic decays of $D_s^+$ favor solutions which have significant
nonfactorized contribution, and, in particular, $R_{sl}$ favors solutions in
scenarios where $A_1(q^2)$ is either flat or decreasing with $q^2$.


title: Planck Scale Physics and the Testability of SU(5) Supergravity GUT

abstract:
  GUT scale threshold corrections in minimal SU(5) supergravity grand
unification are discussed. It is shown that predictions may be made despite
uncertainties associated with the high energy scale. A bound relating the
strong coupling constant to the mass scales associated with proton decay and
supersymmetry is derived, and a sensitive probe of the underlying theory is
outlined. In particular, low energy measurements can in principle determine the
presence of Planck scale ($ 1 / {{\rm M}_{\rm Pl}} $) terms.


title: Left-right symmetry and Neutrino Stability

abstract:
  We consider a left-right symmetric model in which neutrinos acquire mass due
to the spontaneous violation of both the gauged $B-L$ and a global $U(1)$
symmetry broken by the vacuum expectation value (VEV) of a gauge singlet scalar
boson $\VEV{\sigma}$. For suitable choices of $\VEV{\sigma}$ consistent with
all laboratory and astrophysical observations neutrinos will be unstable
against majoron emission. All neutrino masses in the keV to MeV range are
possible, since the expected neutrino decay lifetimes can be short enough to
dilute their relic density below the cosmologically required level. A wide
variety of possible new phenomena, associated to the presence of left-right
symmetry and/or the global symmetry at the TeV scale, could therefore be
observable, without conflict with cosmology. The latter includes the
possibility of invisibly decaying higgs bosons, which can be searched at LEP,
NLC and LHC.


title: Technicolor

abstract:
  Technicolor, with extended technicolor, is the theory of dynamical
electroweak and flavor symmetry breaking at energies far below the Planck
scale. To motivate it, I describe the most important difficulties of the
standard electroweak model of symmetry breaking by elementary scalar bosons. I
then tell how technicolor deals with these difficulties in a way that is both
technically and physically natural. Finally, I discuss the problems of
technicolor, both past and present. (This is the written version of an invited
talk given at the International Conference on the History of Original Ideas and
Basic Discoveries in Particle Physics, Erice, Sicily, 29 July--4 August 1994.)


title:
Vanishing of the Cosmological Constant, Stability of the Dilaton and
  Inflation

abstract:
  We study the possibility of canceling the cosmological constant in
supergravity string models. We show that with a suitable choice of
superpotential the vacuum energy may vanish with the dilaton field at its
minimum and supersymmetry broken with a large hierarchy. We derive the
condition for which the introduction of a chiral potential, e.g. the inflaton
potential, does not destabilize the dilaton field even in the region where the
scalar potential takes positive values. This allows for an inflationary
potential with the dilaton frozen at its minimum.


title: Rho-omega mixing, vector meson dominance and the pion form-factor

abstract:
  We review the current status of rho-omega mixing and discuss its implication
for our understanding of charge-symmetry breaking. In order to place this work
in context we also review the photon-hadron coupling within the framework of
vector meson dominance. This leads naturally to a discussion of the
electromagnetic form-factor of the pion and of nuclear shadowing.


title:
Gravity and the Standard Model with 130 GeV Truth Quark from D4-D5-E6
  Model using 3x3 Octonion Matrices

abstract:
  The D4-D5-E6 model of gravity and the Standard Model with a 130 GeV truth
quark is constructed using 3x3 matrices of octonions. The model has both
continuum and lattice versions. The lattice version uses HyperDiamond lattice
structure.


title: Electroweak instantons at non-zero Weinberg angle

abstract:
  Previous calculations of instanton effects in electroweak theory have
concentrated on the case of zero Weinberg angle $\theta_w$, where the U(1)
hypercharge field decouples. In this paper we extend the instanton calculation
to non-zero $\theta_w$, by constructing a perturbation expansion. This allows
for the first time the study of photon production at B and L number violating
verticies. We find that the orientation of the instanton solution in isospin
space has to be carefully considered to avoid unphysical results.


title: Do we need two Pomerons?

abstract:
  We show that one single Pomeron compatible with the Froissart limit, can
account for all the present HERA data.


title:
Phenomenological implications of supersymmetry in left-right electroweak
  model.

abstract:
  The basics of a supersymmetric left-right model are reviewed. The production
and subsequent decays of the doubly charged triplet higgsino $
\tilde\Delta^{\pm\pm}$ in the Next Linear Collider are discussed. The slepton
pair production in the framework of this model is also analysed.


title: Can the Electroweak Interaction Break Itself?

abstract:
  I examine the possibility that the electroweak interaction breaks itself via
the condensation of fermions in large representations of the weak SU(2)_L gauge
group.


title:
Factorization and SU(2) Heavy Flavor Symmetry for B-Meson Decays
  Producing Charmonium

abstract:
  We show that the factorization assumption in color-suppressed $B$ meson
decays is not ruled out by experimental data on $B \ra K(K^*) +
J/\Psi(\Psi^{'})$. The problem previously pointed out might be due to an
inadequate choice of hadronic form factors. Within the Isgur-Wise SU(2) heavy
flavor symmetry framework, we search for possible $q^2$ dependence of form
factors that are capable of explaining simultaneously the large longitudinal
polarization $\rho_L$ observed in $B \ra K^* + J/\Psi$ and the relatively small
ratio of rates $R_{J/\Psi} = \Gamma(B \ra K^* + J/\Psi)/\Gamma(B \ra K +
J/\Psi)$. We find out that the puzzle could be essentially understood if the
$A_1(q^2)$ form factor is frankly decreasing, instead of being almost constant
or increasing as commonly assumed. Of course, the possibility of understanding
experimental data is not necessarily a proof of factorization.


title: $R_b$ in supergravity models

abstract:
  We compute the supersymmetric contribution to
  $R_{b}\equiv \Gamma (Z\to b{\bar b})/\Gamma (Z\to {\rm hadrons})$ in a
variety of supergravity models. We find $R^{\rm susy}_b\lsim0.0004$, which does
not shift significantly the Standard Model prediction
  ($R^{\rm SM}_b=0.2162$ for $m_t=160\GeV$). An improvement in experimental
precision by a factor of four would be required to be sensitive to such an
effect.


title: Hadronic molecules: meson-baryon hybrids

abstract:
  The existence of hadronic molecular-type hybrids consisting of a baryon and a
meson is argued. Long-range interactions due to one-pion exchange is shown to
be strong enough to produce a loosely bound state. Specific features of a
molecular hybrid are discussed.


title: Top Quarks and Flavor Physics

abstract:
  Because of the top quark's very large mass, about 175~GeV, it now provides
the best window into flavor physics. Thus, pair--production of top quarks at
the Tevatron Collider is the best probe of this physics until the Large Hadron
Collider turns on in the next century. I discuss aspects of the mass and
angular distributions that can be measured in $\ttb$ production with the coming
large data samples from the Tevatron and even larger ones from the LHC.


title: Extended Gauge Sectors

abstract:
  Present and future prospects for the discovery of new gauge bosons, $Z'$ and
$W'$, are reviewed. Particular attention is paid to hadron and $e^+e^-$
collider searches for the $W'$ of the Left-Right Symmetric Model. (Presented at
the {\it Fourth International Conference on Physics Beyond the Standard Model},
Lake Tahoe, CA, December 13-18, 1994.)


title:
Solving the Bethe-Salpeter Equation for Scalar Theories in Minkowski
  Space

abstract:
  The Bethe-Salpeter (BS) equation for scalar-scalar bound states in scalar
theories without derivative coupling is formulated and solved in Minkowski
space. This is achieved using the perturbation theory integral representation
(PTIR), which allows these amplitudes to be expressed as integrals over weight
functions and known singularity structures and hence allows us to convert the
BS equation into an integral equation involving weight functions. We obtain
numerical solutions using this formalism for a number of scattering kernels to
illustrate the generality of the approach. It applies even when the na\"{\i}ve
Wick rotation is invalid. As a check we verify, for example, that this method
applied to the special case of the massive ladder exchange kernel reproduces
the same results as are obtained by Wick rotation.


title: QUANTUM FIELD THEORY OF FERMION MIXING

abstract:
  The fermion mixing transformations are studied in the quantum field theory
framework. In particular neutrino mixing is considered and the Fock space of
definite flavor states is shown to be unitarily inequivalent to the Fock space
of definite mass states. The flavor oscillation formula is computed for two and
three flavors mixing and the oscillation amplitude is found to be momentum
dependent, a result which may be subject to experimental test. The flavor
vacuum state exhibits the structure of $SU(2)$ generalized coherent state.


title: Are there solitons in the two-higgs standard model?

abstract:
  We present some evidence, based on the analysis of lower-dimensional models,
for the possible existence of classically-stable winding solitons in the
two-higgs electroweak theory.


title:
An Upgraded Analysis of $\epsilon\prime/\epsilon$ at the Next-to-Leading
  Order

abstract:
  An upgraded analysis of $\ep$, $x_d$ and $\epp/\ep$, using the latest
determinations of the relevant experimental and theoretical parameters, is
presented. Using the recent determination of the top quark mass, $m_t=(174 \pm
17)$ GeV, our best estimate is $\epp/\ep= 3.1 \pm 2.5 $, which lies in the
range given by E731. We describe our determination of $\epp/\ep$ and make a
comparison with other similar studies. A detailed discussion of the matching of
the full theory to the effective Hamiltonian, written in terms of lattice
operators, is also given.


title: Phase equilibration in bubble collisions

abstract:
  In the context of an Abelian gauge symmetry, spontaneously broken at a
first-order transition, we discuss the evolution of the phase difference
between the Higgs fields in colliding bubbles. We show that the effect of
dissipation, represented by a finite plasma conductivity, is to cause the
phases to equlibrate on a time-scale, determined by the conductivity, which can
be much smaller than the bubble radii at the time of collision. Currents
induced during the phase equilibration generate a magnetic flux, which is
determined by the initial phase difference. In a three-bubble collision, the
fluxes produced by each pair of bubbles combine, and a vortex can be formed. We
find that, under most conditions, the probability of trapping magnetic flux to
form a vortex is correctly given by the ``geodesic rule''.


title: HIGGS BOSON PRODUCTION IN $e^+ e^- \to \mu^+ \mu^- b \bar b$

abstract:
  The production of the Standard Model Higgs boson in the four-fermion reaction
$e^+ e^- \to \mu^+ \mu^- b \bar b$ is studied. The complete tree-level matrix
element, including signal and backgrounds in the standard electroweak theory,
is computed and initial state radiation is taken into account in the
leading-log approximation. A Monte Carlo event generator has been built and
numerical results for some distributions of experimental interest for the
search of the Higgs particle at future electron-positron colliders are shown,
compared with those existing in the literature and commented.


title:
Condensation effects beyond one loop in the Top-mode Standard Model
  without gauge bosons

abstract:
  We study dynamical symmetry breaking in the Standard Model including the
next-to-leading order terms. We introduce at a high, but finite, energy scale
Lambda a top quark condensate H={t {bar t}} and derive, using path integral
methods, the effective potential including quadratic fluctuations in the scalar
field H. We neglect the contributions of all components of the massive
electroweak gauge bosons. The existence of a non-trivial minimum in the
effective potential leads to the condition that the cut-off Lambda is limited
from above: Lambda < Lambda_{crit} approx 4.7 m_t^{phys.} (for N_c = 3), and to
a new lower bound for the 4-fermion coupling a = (G N_c Lambda^2)/(8 pi^2) >
1.60. Similar results are obtained if we demand, instead, that the
next-to-leading order contributions not shift the location
z=(m_t^{bare}/Lambda)^2 of the minimum drastically, e.g.~by not more than a
factor of 2. The results are reproduced diagrammatically, where the leading
plus all the next-to-leading order diagrams in the (1/N_c)-expansion are
included. Dominant QCD effects are also included, but their impact on the
numerical results is shown to be small.


title: Theories of Non-Experiments in Coherent Decays of Neutral Mesons

abstract:
  Many theoretical calculations of subtle coherent effects in quantum mechanics
do not carefully consider the interface between their calculations and
experiment. Calculations for gedanken experiments using initial states not
satisfied in realistic experiments give results requiring interpretation.
Confusion and ambiguities frequently arise. Calculations for time-dependent
mixing oscillations describe non-experiments. Physical experiments describe
oscillations in space in the laboratory system resulting from interference
between waves having the same energy and time dependence; $not$ different
momenta and space dependence. Time-dependent oscillations are not observed.


title:
Single Spin Asymmetries in Proton-Proton and Proton-Neutron Scattering
  at 820 GeV

abstract:
  The physics case is summarised for the investigation of high energy spin
phenomena by placing an internal polarised target into HERA's unpolarised
proton beam. The luminosity and experimental sensitivity are discussed.
Estimating the physics reach of single spin asymmetries in different final
states reveals a considerable physics potential in testing the spin sector of
perturbative QCD.


title:
Constraints on cosmic charge asymmetry and neutrino charge from the
  microwave background

abstract:
  Considering the observed anisotropy in cosmic microwave background radiation
($\Delta T/T \leq 10^{-4}$) an upper limit on the electric charge asymmetry
over a cosmological scale is found which is several orders more stringent than
those found earlier. The same argument constrains the charge of massless,
degenerate neutrinos.


title:
OBLIQUE RADIATIVE CORRECTIONS IN THE VECTOR CONDENSATE MODEL OF
  ELECTROWEAK INTERACTIONS

abstract:
  Oblique radiative corrections are calculated to the parameter $S$ in a
version of the standard model where the Higgs doublet is replaced by a doublet
of vector bosons and the gauge symmetry is broken dynamically. We show that to
each momentum scale there exists a domain of the masses of charged and neutral
vector bosons where $S$ is compatible with the experiments. At a scale of 1 TeV
this requires vector boson masses of at least $m_0 \approx $ 400--550 GeV, $
m_+ \approx $ 200--350 GeV.


title:
THE DYSON-SCHWINGER EQUATION FOR A MODEL WITH INSTANTONS - THE SCHWINGER
  MODEL

abstract:
  Using the exact path integral solution of the Schwinger model -- a model
where instantons are present -- the Dyson-Schwinger equation is shown to hold
by explicit computation. It turns out that the Dyson-Schwinger equation
separately holds for every instanton sector. This is due to Theta-invariance of
the Schwinger model.


title:
Search for new physics indirect effects in $e^+e^-\to W^+W^-$ at linear
  colliders with polarized beams

abstract:
  We discuss the potential of a $0.5\hskip 2pt TeV$ linear collider to explore
manifestations of extended (or alternative) electroweak models of current
interest, through measurements of the reaction $e^+e^-\to W^+W^-$ with both
initial and final states polarization. Specifically, we consider the
possibility to put stringent constraints on lepton mixing (or extended lepton
couplings) and $Z-Z^\prime$ mixing, showing in particular the usefulness of
polarization in order to disentangle these effects.


title: Constraining Supersymmetric SO(10) Models Through Cosmology

abstract:
  We study the impact of the symmetry breaking patterns from supersymmetric
SO(10) down to the standard model on the standard big-bang cosmology through
the formation of topological defects. None of the models is consistent with the
standard cosmology without invoking any mechanism to solve the monopole
problem. For this purpose, we use a hybrid false vacuum inflationary scenario.
Only two symmetry breaking patterns are consistent with these topological
considerations and with the actual data on the proton lifetime.


title:
Estimates for Forward-backward Asymmetry in $B\rightarrow K^*(892)\; l^+
  l^-$

abstract:
  Forward-backward charge asymmetry in rare dilepton $B$-decays is formulated
with the assumption of an on-shell b-quark. We find the asymmetry is expressed
in terms of two spatially transverse helicity amplitudes, which are determined
by combining the data of $D\rightarrow K^*(892)\; l^+ \nu$ with heavy flavour
symmetry. We estimate the charge asymmetry of $B\rightarrow K^*(892)\; l^+ l^-$
for large energy leptons against various top masses in the standard model.


title: Precision Corrections to Supersymmetric Unification

abstract:
  We compute the full set of weak-scale gauge and Yukawa threshold corrections
in the minimal supersymmetric standard model, including all finite
(non-logarithmic) corrections, which we show to be important. We use our
results to examine the effects of unification-scale threshold corrections in
the minimal and missing-doublet SU(5) models. We work in the context of a
unified mass spectrum, with scalar mass M_0 and gaugino mass M_1/2, and find
that in minimal SU(5) with squark masses less than one TeV, successful gauge
and Yukawa coupling unification requires M_1/2 << M_0 and M_0 \simeq 1 TeV. In
contrast, we find that the missing-doublet model permits gauge and Yukawa
unification for a wide range of supersymmetric masses.


title: Semi-Relativistic Hamiltonians of Apparently Nonrelativistic Form

abstract:
  We construct effective Hamiltonians which despite their apparently
nonrelativistic form incorporate relativistic effects by involving parameters
which depend on the relevant momentum. For some potentials the corresponding
energy eigenvalues may be determined analytically. Applied to two-particle
bound states, it turns out that in this way a nonrelativistic treatment may
indeed be able to simulate relativistic effects. Within the framework of hadron
spectroscopy, this lucky circumstance may be an explanation for the sometimes
extremely good predictions of nonrelativistic potential models even in
relativistic regions.


title: RENORMALIZATION and the EQUIVALENCE THEOREM: ON-SHELL SCHEME

abstract:
  We perform an exhaustive analysis of the Equivalence Theorem both in the
minimal Standard Model and in an Effective Electroweak Chiral Lagrangian up to
${\cal O}(p^4)$. We have considered the leading corrections to the usual
prescription consisting in just replacing longitudinally polarized $W$ or $Z$
by the corresponding Goldstone bosons. The corrections appear through an
overall constant multiplying the Goldstone boson amplitude as well as through
additional diagrams. By including them we can extend the domain of
applicability of the Equivalence Theorem, making it suitable for precision
tests of the symmetry breaking sector of the Standard Model. The on-shell
scheme has been used throughout. When considering the Equivalence Theorem in an
Effective Chiral lagrangian we analyze its domain of applicability, as well as
several side issues concerning gauge fixing, Ward identities, on-shell scheme
and matching conditions in the effective theory. We have analyzed in detail the
processes $W^+ W^- \to W^+W^-$ and $W^+W^+\to W^+W^+$ to illustrate the points
made.


title:
Spontaneous Chiral-Symmetry Breaking in Three-Dimensional QED with a
  Chern--Simons Term

abstract:
  In three-dimensional QED with a Chern--Simons term we study the phase
structure associated with chiral-symmetry breaking in the framework of the
Schwinger--Dyson equation. We give detailed analyses on the analytical and
numerical solutions for the Schwinger--Dyson equation of the fermion
propagator, where the nonlocal gauge-fixing procedure is adopted to avoid
wave-function renormalization for the fermion. In the absence of the
Chern--Simons term, there exists a finite critical number of four-component
fermion flavors, at which a continuous (infinite-order) chiral phase transition
takes place and below which the chiral symmetry is spontaneously broken. In the
presence of the Chern--Simons term, we find that the spontaneous
chiral-symmetry-breaking transition continues to exist, but the type of phase
transition turns into a discontinuous first-order transition. A simple
stability argument is given based on the effective potential, whose stationary
point gives the solution of the Schwinger-Dyson equation.


title:
Effective Hamiltonian for $B \ra X_s e^+ e^-$ Beyond Leading Logarithms
  in the NDR and HV Schemes

abstract:
  We calculate the next-to-leading QCD corrections to the effective Hamiltonian
for \Bsee in the NDR and HV schemes. We give for the first time analytic
expressions for the Wilson Coefficient of the operator $Q_9 = (\bar s
b)_{V-A}(\bar e e)_V$ in the NDR and HV schemes. Calculating the relevant
matrix elements of local operators in the spectator model we demonstrate the
scheme independence of the resulting short distance contribution to the
physical amplitude. Keeping consistently only leading and next-to-leading
terms, we find an analytic formula for the differential dilepton invariant mass
distribution in the spectator model. Numerical analysis of the $\mt$, $\Lms$
and $\mu \approx {\cal O}(\mb)$ dependences of this formula is presented. We
compare our results with those given in the literature.


title: DEEP INELASTIC SCATTERING FROM POLARIZED DEUTERONS

abstract:
  The spin-dependent structure function of the deuteron, g_1D, is calculated
within a covariant framework. The off-shell structure of the bound nucleon
gives corrections to the convolution model at a level of half a percent for x
below 0.7, increasing to more than five percent at larger x. Overall, the
dominant source of error comes from the lack of knowledge associated with the
deuteron D-state, which may introduce an uncertainty in the neutron spin
structure function, g_1n, extracted from deuterium data of up to ten percent
for x around 0.2.


title: Neutrino spin-flip effects in collapsing stars

abstract:
  We study the spin-flavor transitions of neutrinos in the magnetic fields of a
collapsing star. For the neutrino mass squared difference (10^{-10} - 10) eV^2
the transitions take place in almost isotopically neutral region of the star,
where the effective matter density is suppressed up to 3 - 4 orders of
magnitude. This suppression is shown to increase the sensitivity of the
neutrino bursts studies to the magnetic moment of neutrino by 1.5 - 2 orders of
magnitude, and for realistic magnetic field the observable effects may exist
for (2 - 3)10^{-14} Bohr magneton. In the isotopically neutral region the jumps
of the effective potential exist which influence the probabilities of
transitions. The experimental signatures of the spin-flavor transitions are
discussed. In particular, in the case of direct mass hierarchy, the spin-flip
effects result in a variety of modifications of the electron antineutrino
spectrum. Taking this into account, we estimated the upper bounds on the
magnetic moment from the SN1987A data. In the isotopically neutral region the
effects of possible twist of the magnetic field on the way of neutrinos can be
important, inducing distortion of the neutrino energy spectra and further
increasing the sensitivity. However, if the total rotation angle is restricted
the absolute change of probabilities is small.


title: Formation of Vortices in First Order Phase Transitions

abstract:
  Using a toy model Lagrangian we investigate the formation of vortices in
first order phase transitions. The evolution and interactions of vacuum bubbles
are also studied using both analytical approximations and a numerical
simulation of scalar field dynamics. A long lived bubble wall bound state is
discovered and its existence is justified by using a simplified potential for
the bubble wall interaction. The conditions that need to be satisfied for
vortex formation by bubble collisions are also studied with particular emphasis
placed on geometrical considerations. These conditions are then implemented in
a Monte Carlo simulation for the study of the probability of defect formation.
It is shown that the probability of vortex formation by collision of
relativistically expanding bubbles gets reduced by about 10% due to the above
mentioned geometric effects.


title:
Deriving Non-decoupling Effects of Heavy Fields from the Path Integral:
  a Heavy Higgs Field in an SU(2) Gauge Theory

abstract:
  We describe a method to remove non-decoupling heavy fields from a quantized
field theory and to construct a low-energy one-loop effective Lagrangian by
integrating out the heavy degrees of freedom in the path integral. We apply
this method to the Higgs boson in a spontaneously broken SU(2) gauge theory
(gauged linear sigma-model). In this context, the background-field method is
generalized to the non-linear representation of the Higgs sector by applying (a
generalization of) the Stueckelberg formalism. The (background) gauge-invariant
renormalization is discussed. At one loop the log M_H-terms of the heavy-Higgs
limit of this model coincide with the UV-divergent terms of the corresponding
gauged non-linear sigma-model, but vertex functions differ in addition by
finite (constant) terms in both models. These terms are also derived by our
method. Diagrammatic calculations of some vertex functions are presented as
consistency check.


title: Radiative Corrections to $\pi_{l2}$ and $K_{l2}$ Decays

abstract:
  We reexamine radiative corrections to $\pi_{l2}$ and $K_{l2}$ decays. We
perform a matching calculation, including vector and axial vector resonances as
explicit degrees of freedom in the long distance part. By considering the
dependence on the matching scale and on the hadronic parameters, and by
comparing with model independent estimates, we scrutinize the model dependence
of the results. For the pseudoscalar meson decay constants, we extract the
values f_pi = (92.1 \pm 0.3) MeV and f_K = (112.4 \pm 0.9) MeV. For the ratios
R_pi and R_K of the electronic and muonic decay modes, we predict R_pi =
(1.2354 \pm 0.0002) 10^{-4} and R_K = (2.472 \pm 0.001) 10^{-5}.


title:
Bs-Bs.bar Mixing, CP Violation and Extraction of CKM Phases from
  Untagged Bs Data Samples

abstract:
  A width difference of the order of 20\% has previously been predicted for the
two mass eigenstates of the $B_s$ meson. The dominant contributor to the width
difference is the $b\rightarrow c\bar c s$ transition, with final states common
to both $B_s$ and $\overline{B}_s$. All current experimental analyses fit the
time-dependences of flavor-specific $B_s$-modes to a single exponential, which
essentially determines the average $B_s$ lifetime. We stress that the same data
sample allows even the measurement of the width difference. To see that, this
note reviews the time-dependent formulae for tagged $B_s$ decays, which involve
rapid oscillatory terms depending on $\Delta mt$. In untagged data samples the
rapid oscillatory terms cancel. Their time-evolutions depend only on the much
more slowly varying exponential falloffs. We discuss in detail the extraction
of the two widths, and identify the large (small) CP-even (-odd) rate with that
of the light (heavy) $B_s$ mass eigenstate. It is demonstrated that decay
length distributions of some \underline{untagged} $B_s$ modes, such as $\rho^0
K_S, \; D_s^{(*)\pm}K^{(*)\mp}$, can be used to extract the notoriously
difficult CKM unitarity triangle angle $\gamma$. Sizable CP violating effects
may be seen with such untagged $B_s$ data samples. Listing $\Delta\Gamma$ as an
observable allows for additional important standard model constraints. Within
the CKM model, the ratio $\Delta\Gamma/ \Delta m$ involves no CKM parameters,
only a QCD uncertainty. Thus a measurement of $\Delta\Gamma \;(\Delta m)$ would
predict $\Delta m \;(\Delta\Gamma )$, up to the QCD uncertainty. A large width
difference would automatically solve the puzzle of the number of charmed
hadrons per $B$ decay in favor of theory. We also derive an upper limit of $(|
\Delta\Gamma | / \Gamma)_{B_s} <~ 0.3$. Further, we must abandon the notion of
branching fractions of $B_s\rightarrow f$, and instead consider $
B(B^0_{L(H)}\rightarrow f)$, in analogy to the neutral kaons.


title:
$Z_2\times Z_2$ orbifold compactification -- the origin of realistic
  free fermionic models

abstract:
  All the realistic free fermionic models utilize a set of basis vectors, the
NAHE set, that correspond to $Z_2\times Z_2$ orbifold compactification with
nontrivial background fields. I argue that the realistic features of free
fermionic models, like the number of generations and the fermion mass spectrum
are due to the underlying $Z_2\times Z_2$ orbifold compactification.


title:
On the role of the quark mass thresholds in extrapolations of the
  running \alpha_s

abstract:
  The accuracy of the conventional treatment of quark mass thresholds in the
QCD running coupling constant $\alpha_s$, based on the step approximation to
the $\beta$--function, is investigated. The errors of extrapolating $\ase(\mu)$
from low energies to $\mu=M_Z$, implied by this approximation, are shown to be
of the same magnitude as the typical next--to--next--to--leading order
contributions to \as and tend to increase the resulting \as. The importance of
the proper choice of matching points is emphasized.


title: Inclusive Two--Photon Reactions at TRISTAN

abstract:
  After briefly reviewing past accomplishments of TRISTAN experiments in the
field of inclusive two--photon reactions, I discuss open problems in the Monte
Carlo simulation of such reactions. The main emphasis is on multiple
scattering, i.e. events where at least two pairs of partons scatter within the
same \gaga collision to form at least four (mini)jets. The cross section for
such events might just be observable at TRISTAN. While theoretical arguments
for the existence of such events are strong, they have not yet been directly
observed experimentally, thereby potentially opening a new opportunity for
TRISTAN experiments.


title: Charm and Beauty in Particle Physics

abstract:
  The spectra of states containing charmed and beauty quarks, and their
regularities, are reviewed.


title: Gluon Radiation Off Scalar Stop Particles

abstract:
  We present the distributions for gluon radiation off stop-antistop particles
produced in $e^+e^-$ annihilation: $e^+e^- \to \tilde t \bar{\tilde t} g$. For
high energies the splitting functions of the fragmentation processes $\tilde t
\to \tilde t g$ and $g \to \tilde t \bar{\tilde t}$ are derived; they are
universal and apply also to high-energy stop particles produced at hadron
colliders.


title: A new cosmological constant model

abstract:
  We propose a new cosmological model with a time-dependent cosmological
constant ($\Lambda\propto 1/t^2$), which starting at the Planck time as
$\Lambda_{Pl}\sim M^2_{Pl}$, evolves to the present-day allowed value of
$\Lambda_0\sim10^{-120}M^2_{Pl}$. This scenario is supported by non-critical
string theory considerations. We compute the age of the Universe and the
time-dependence of the scale factor in this model, and find general agreement
with recent determinations of the Hubble parameter for substantial values of
$\Omega_{\rm \Lambda}$. This effectively low-density open Universe model
differs from the traditional cosmological constant model, and has observable
implications for particle physics and cosmology.


title:
Possible Higgs Boson Effects on the Running of Third and Fourth
  Generation Quark Masses and Mixings.

abstract:
  The Schwinger-Dyson equation for the quark self-energy is solved for the case
of the third and fourth quark generations. The exchanges of standard model
gluons and Higgs bosons are taken into account. It is found that Higgs boson
exchange dominates quark self-energy in the ultraviolet region for sufficiently
large input quark masses, causing the running quark propagator mass to increase
with energy-scale. No running of the quark mixing angles is found for input
quark masses up to and including 500 GeV.


title:
Rephase-Invariant CP-Violating Observables and Mixings in the $B^0$,
  $D^0$, $K^0$ Systems.

abstract:
  We present a general model-independent and rephase-invariant formalism that
cleanly relates observables to the fundamental parameters and explicitly
separates different types of CP violation in the $B^0$-, $D^0$- and $K^0$-
systems. We emphasize its importance when interpreting experimental measurement
of CP violation, the unitarity triangle, and probes of new physics.


title: QCD Radiative Corrections to the Leptonic Decay Rate of the B_c Meson

abstract:
  The QCD radiative corrections to the leptonic decay rate of the $B_c$ meson
are calculated using the formalism of nonrelativistic QCD (NRQCD) to separate
short-distance and long-distance effects. The $B_c$ decay constant is factored
into a sum of NRQCD matrix elements each multiplied by a short-distance
coefficient. The short-distance coefficient for the leading matrix element is
calculated to order $\alpha_s$ by matching a perturbative calculation in full
QCD with the corresponding perturbative calculation in NRQCD. This
short-distance correction decreases the leptonic decay rate by approximately
$15\%$.


title: SOFFER'S INEQUALITY

abstract:
  Various issues surrounding a recently proposed inequality among twist-two
quark distributions in the nucleon are discussed. We provide a rigorous
derivation of the inequality in QCD, including radiative corrections and scale
dependence. We also give a more heuristic, but more physical derivation, from
which we show that a similar inequality does not exist among twist-three quark
distributions. We demonstrate that the inequality does not constrain the
nucleon's tensor charge. Finally we explore physical mechanisms for saturating
the inequality, arguing it is unlikely to occur in Nature.


title: A Complete Supersymmetric SO(10) Model

abstract:
  A complete supersymmetric SO(10) model is constructed, which is the most
general consistent with certain $R$, discrete, and $U(1)$ flavor symmetries.
The desired vacuum of the theory has vevs which lie in particular directions of
group space. This leads to both doublet triplet splitting and to the generation
of just four operators for charged fermion masses. The model illustrates how
many features of superunification become related in the context of a complete
theory. The features discussed here include: the weak mixing angle prediction,
the doublet-triplet splitting problem, proton decay, the generation of the
$\mu$ parameter, neutrino masses and the generation of the operators which lead
to charged fermion mass predictions.


title:
Quark Mass Matrix with a Structure of a Rank One Matrix Plus a Unit
  Matrix

abstract:
  A quark mass matrix model $M_q=M_e^{1/2} O_q M_e^{1/2} $ is proposed where
$M_e^{1/2}={\rm diag}(\sqrt{m_e},\sqrt{m_\mu},\sqrt{m_\tau})$ and $O_q$ is a
unit matrix plus a rank one matrix. Up- and down-quark mass matrices $M_u$ and
$M_d$ are described in terms of charged lepton masses and additional three
parameters (one in $M_u$ and two in $M_d$). The model can predict reasonable
quark mass ratios (not only $m_u/m_c$, $m_c/m_t$, $m_d/m_s$ and $m_s/m_b$, but
also $m_u/m_d$) and Kobayashi-Maskawa matrix elements.


title:
Heavy Higgs production and decay via $e^+e^-\to Z^0 H^0 \to b\bar
  bZ^0Z^0$ and irreducible backgrounds at Next Linear Colliders

abstract:
  The complete matrix element for $e^+e^-\ar b\bar bZ^0Z^0$ has been computed
at tree--level and applied to $Z^0H^0$--production followed by $Z^0\ar b\bar b$
and $H^0\ar Z^0Z^0$, including all the irreducible background, at Next Linear
Colliders. We find that, assuming flavour identification of the $Z^0$--decay
products, this channel, together with $e^+e^-\ar b\bar bW^+W^-$ in which
$Z^0H^0\ar (b\bar b)(W^+W^-$), can be important for the study of the parameters
of the Standard Model Higgs boson over the heavy mass range $2M_{Z^0}\Ord
M_{H^0}\Ord 2{m_t}$.


title: ANOTHER LOOK AT THE EINSTEIN-MAXWELL EQUATIONS

abstract:
  An electric monopole solution to the equations of Maxwell and Einstein's
general relativity is displayed. It differs from the usual one in that all
components of the metric vanish at large spatial distances from the charge
rather than approaching the Minkowski metric. This enables us to find an
approximate solution to that for many charges.


title: Spin content from skyrmions with parameters fit to baryon properties

abstract:
  Earlier work reported on the existence of a term within a generalized
skyrmion approach that yields appreciable spin content for the proton.
Unfortunately there is no accessible experiment that can fix the coefficient of
this term directly; plausible but highly uncertain values for it gave a result
for the spin content loosely consistent with the currently measured
$\Delta\Sigma = 0.27\pm 0.13.$ We here attempt to narrow the range of values
for this coefficient by performing global fits to all the parameters of the
generalized Skyrme lagrangian while requiring reasonable results for the baryon
octet and decuplet masses and octet magnetic moments. This requirement fixes
the coefficient loosely, and we find that parameter sets that fit the baryon
masses and magnetic moments yield proton spin content near $\Delta\Sigma \sim
0.15.$


title:
CORRECTIONS OF ORDER $\alpha^2(Z\alpha)^5$ TO HYPERFINE SPLITTING AND
  LAMB SHIFT

abstract:
  Corrections to hyperfine splitting and Lamb shift of order
$\alpha^2(Z\alpha)^5$ induced by the diagrams with radiative photon insertions
in the electron line are calculated in the Fried-Yennie gauge. These
contributions are as large as $-7.725(3)\alpha^2(Z\alpha)^5/(\pi
n^3)(m_r/m)^3m$ and $-0.6711(7)\alpha^2(Z\alpha)/(\pi n^3)E_F$ for the Lamb
shift and hyperfine splitting, respectively. Phenomenological implications of
these results are discussed with special emphasis on the accuracy of the
theoretical predictions for the Lamb shift and experimental determination of
the Rydberg constant. New more precise value of the Rydberg constant is
obtained on the basis of the improved theory and experimental data.


title: Dynamical Chiral Symmetry Breaking by a Magnetic Field in QED

abstract:
  It is shown that the chiral symmetry is spontaneously broken by a constant
magnetic field in QED. The dynamical mass of fermions (energy gap in the
fermion spectrum) is $m_{dyn}\simeq
C\sqrt{eB}\exp\left[-\left(\pi/\alpha\right) ^{1/2}\right]$, where $B$ is the
magnetic field, the constant $C$ is of order one and $\alpha=e^2/4\pi$ is the
renormalized coupling constant. Possible applications of this effect are
discussed.


title:
The Bosonic Sector of the Electroweak Interactions, Status and Tests at
  Present and Future Colliders

abstract:
  The status of the Standard Model (SM) is reviewed. We emphazize the fact that
in spite of the success of the SM for the descrition of the fermionic sector,
the status of the bosonic sector (gauge and scalar) suffers from many
theoretical deficiencies and from the lack of empirical support. This
situation, which leaves room for several types of extensions or alternatives to
SM, strongly motivates the pursue of intense efforts for finding hints of New
Physics (NP) effects. We present a phenomenological description valid for
energies lying below the NP scale. We discuss the indirect constraints
established from high precision tests at LEP1, as well as the direct tests that
could be performed at future machines


title: Mixed Dark Matter and the Fate of Baryon and Lepton Symmetries

abstract:
  The available data on large scale structures seem to favour models with mixed
dark matter (MDM), i.e. with a hot and cold component in a rather well--defined
amount, or with some form of ``warm" dark matter. I discuss some prospects for
these new scenarios for DM in the context of supersymmetric extensions of the
electroweak standard model. In particular, I emphasize the intriguing link
which exists between the present prospects of solution of the DM puzzle and the
explicit or spontaneous breaking of baryon and/or lepton number symmetries.
Some consequences on the issue of baryogenesis are worked out.


title: QCD Scaling Violation at Small x

abstract:
  We investigate the evolution of parton densities at small values of the
momentum fraction, x, by including resummed anomalous dimensions in the
renormalization group equations. The resummation takes into account the
leading-logarithmic contributions (\alpha_S \ln x)^k given by the BFKL equation
and the next-to-leading-logarithmic corrections from quark evolution. We
present numerical results for the parton densities and the deep inelastic
structure function F_2.