title: QCD Corrections to Charmless $b \to s$ Processes

abstract:
  QCD corrections to the penguin induced charmless inclusive $B$ decays are
performed to an improved leading-log approximation. For process $b \to s
q\overline{q} $ (q=uds) and $ b \overline{q} \to s \overline{q} $, four
previous missed 4-quark operators are included to make a complete leading log
QCD corrected result. Furthermore, part of the next-leading log effect was also
given for the above processes and process $b \to s g$. In comparison to
previous QCD corrected calculations by Grigjanis et al., the inclusive decay
rates for process $b \to s q\overline{q} $ (q=ud), $b\to s s\overline{s}$ and $
b \overline{q} \to s \overline{q} $ are suppressed 10\%, 14\% and 18\%
respectively. The branching ratio of process $b \to s g$ is enhanced by 2-3
orders, the result for this process is in agreement with the result of Ciuchini
et al.


title: Hadronic production of B_c-mesons

abstract:
  On the basis of the exact formulas of QCD perturbation theory and parton
model the hadronic production cross-sections for $B_c({B_c}^*)$-mesons
($1^1S_0,1^3S_1,2^1S_0,2^3S_1$-states) are calculated. The method used is the
direct calculation of appropriate amplitudes with the help of a FORTRAN program
and subsequent Monte-Carlo integration over the phase space and convolution
with the structure functions.


title: Colored Chaos

abstract:
  I review recent progress in our understanding of the basis of statistical
models for hadronic reactions and of the mechanisms of thermalization in
nonabelian gauge theories. (Invited talk given at the NATO Advanced Research
Workshop on Hot Hadronic Matter: Theory and Experiment, Divonne-le-Bains, June
1994) **Note: The PostScript file of one figure is too large to be easily
transmitted; I will mail a hardcopy upon request.


title:
Evolution of the Disoriented Chiral Condensates in the Mean Field
  Approximation

abstract:
  We study the dynamics of the chiral phase transition expected during the
expansion of the quark-gluon plasma produced in a high energy hadron or heavy
ion collision, using the $O(4)$ linear sigma model in the mean field
approximation. Starting from an approximate equilibrium configuration at an
initial proper time $\tau$ in the disordered phase, we study the transition to
the ordered broken symmetry phase as the system expands and cools. We give
results for the proper time evolution of the effective pion mass and for the
pion two point correlation function. We investigate the possibility of
disoriented chiral condensate being formed during the expansion. In order to
create large domains of disoriented chiral condensates low-momentum
instabilities have to last for long enough periods of time. Our simulations
show no instabilities for an initial thermal configuration. For the
far-of-equilibrium cases studied, the instabilities are formed during the
initial stages of the expansion survive for short proper times. For slow
expansion rates even such configurations do not develop instabilities.


title: Photonic production of B_c-mesons

abstract:
  The cross section of the $\gamma \gamma \rightarrow B_c(B_c^*) \bar b c $
process is calculated. It is shown that near threshold the pseudoscalar state
production is much suppressed with respect to the vector one. At large energies
their ratio becaims $\sigma(B_c^*)/sigma(B_c)\sim 4$. The process of heavy
quark recombination dominates in the production of $B_c(B_c^*)$ states. The
fragmentation process $b\to B_c$ comes to play at high $p_t$ values only, while
its contribution will remain nondominant.


title: Gauge fixing by unitary transformations in QCD

abstract:
  The unitary gauge fixing technique is applied to the QCD hamiltonian
formulated in terms of angular variables. It is demonstrated that in this
formulation projections on the physical Hilbert space are unnecessary to
separate physical and unphysical degrees of freedom. Therefore the application
of the unitary gauge fixing technique can be extended to the operator level.


title: The hamiltonian formulation of QCD in terms of angle variables

abstract:
  For the sake of eliminating gauge variant degrees of freedom we discuss the
way to introduce angular variables in the hamiltonian formulation of QCD. On
the basis of an analysis of Gauss' law constraints a particular choice is made
for the variable transformation from gauge fields to angular field variables.
The resulting formulation is analogous to the one of Bars in terms of corner
variables. Therefore the corner or angle formulation may constitute an useful
starting point for the investigation of the low energy properties of QCD in
terms of gauge invariant degrees of freedom.


title:
Theoretical Update on the Model-Independent Determination of |V_{cb}|
  Using Heavy Quark Symmetry

abstract:
  In view of new precise measurements of the $\bar B\to D^*\ell \bar\nu$ decay
rate near zero recoil, we reconsider the theoretical uncertainties in the
extraction of $| V_{cb}|$ using heavy quark symmetry. In particular, we combine
our previous estimate of $1/m_Q^2$ corrections to the normalization of the
hadronic form factor at zero recoil with sum rules derived by Shifman {\it et
al}. to obtain a new prediction with less theoretical uncertainty. We also
summarize the status of the calculation of short-distance corrections, and of
the slope of the form factor at zero recoil. We find ${\cal F}(1)=\eta_A
\hat\xi(1)=0.93\pm 0.03$ and $\hat\varrho^2=0.7\pm 0.2$. Combining this with
the most recent experimental results, we obtain the model-independent value $|
V_{cb}|=0.040\pm 0.003$.


title: The Nucleon Spin Problem

abstract:
  C o n t e n t s 1. Introduction. 2. General Relations. 3. Small $x$ Domain --
Regge Behaviour. 4. The Parton Model. 5. Sum Rules in the Parton Model. 6. QCD
Corrections to Sum Rules. 7. Nucleon Axial Coupling Constants. 8. The
Experimental Data on $g_1(x)$ and Their Interpretation. 9. Suggestions for
Future Experiments. 10. The Structure Function $g_2(x)$. 11. Chirality
Violating Structure Function $h_1(x)$. 12. Conclusions.


title: The trace anomaly and the parton model

abstract:
  The trace anomaly is relevant to the renormalisation of the unpolarised
parton distributions. The role of the trace anomaly in F_2 is compared with the
axial anomaly in g_1.


title: Associate Sneutrino-Neutralino/Chargino Production at LEPxLHC

abstract:
  We examine for representative gaugino-higgsino mixing scenarios
sneutrino-neutralino and sneutrino-chargino production in deep inelastic
ep-scattering at the cm-energy of 1.8 TeV. The cross sections for
sneutrino-chargino production are more than one order of magnitude bigger than
those for sneutrino-squark production. Also for zino-like neutralinos we find
cross sections at least comparable to those for sneutrino-squark production.


title: E2 Strength in the Radiative Charmed Baryon Decay

abstract:
  The radiative decay $\Sigma_Q^* \rightarrow \Lambda_Q\gamma$ can have both
magnetic dipole (M1) and electric quadrupole (E2) components. In the heavy
quark limit $M_Q\rightarrow\infty$ the transition arises from the spin of the
light degrees of freedom changing from $s_l=1$ to $s_l=0$ and hence the E2
contribution vanishes. We compute the leading contribution to the E2 strength
in chiral perturbation theory and find that the amplitude is enhanced by a
small energy denominator in the chiral limit. This enhancement essentially
compensates for the $1/M_c$ suppression that is present in the charm system. We
find a mixing ratio of order a few percent dependent upon the
$\Sigma_c^*--\Sigma_c$ spin symmetry breaking mass difference. The analogous
quantity in the b-baryon sector is smaller by a factor of $\sim M_c/M_b$.


title:
Amplitude Zeros and Rapidity Correlations in $W\gamma$ and $WZ$
  Production in Hadronic Collisions

abstract:
  A comparative study of amplitude zeros in $W\gamma$ and $WZ$ production in
hadronic collisions is presented. The Standard Model amplitude for $q_1 \bar
q_2 \rightarrow W^\pm Z $ at the Born-level is shown to exhibit an approximate
zero located at $\cos\theta = (g^{q_1}_{-} + g^{q_2}_{-}) / (g^{q_1}_{-} -
g^{q_2}_{-})$ at high energies, where the $g^{q_i}_{-}$ ($i=1,2$) are the
left-handed couplings of the $Z$-boson to quarks and $\theta$ is the center of
mass scattering angle of the $W$-boson. This approximate zero is similar to the
well-known radiation zero in $W\gamma$ production. Prospects to observe the
amplitude zeros using rapidity correlations between the final state particles
are explored.


title: Detecting Tau Neutrino Oscillations at PeV Energies

abstract:
  It is suggested that a large deep underocean (or ice) neutrino detector,
given the presence of significant numbers of neutrinos in the PeV energy range
as predicted by various models of Active Galactic Nuclei, can make unique
measurements of the properties of neutrinos. It will be possible to observe the
existence of the tau neutrino, measure its mixing with other flavors, in fact
test the mixing pattern for all three flavors based upon the mixing parameters
suggested by the atmospheric and solar neutrino data, and measure the tau
neutrino cross section. The key signature is the charged current tau neutrino
interaction, which produces a double cascade, one at either end of a lightly
radiating track. At a few PeV these cascades would be separated by roughly 100
m, and thus be easily resolvable in next generation DUMAND-like detectors.
First examples might be found in detectors presently under construction. Future
applications are precise neutrino astronomy and earth tomography. This paper is
an expanded version of hep-ph/9405296, for publication.


title: QCD Corrections to $b \to s \gamma$ Decay in 2-Higgs Doublet Model

abstract:
  We give a more complete calculation of $b \to s\gamma $ decay in 2-Higgs
doublet model, including leading log QCD corrections from $m_{top}$ to $M_W$ in
addition to corrections from $M_{W}$ to $m_b$. The inclusive decay rate in the
first model is found to be suppressed 23\% comparing with the calculations
without the QCD running from $m_{top}$ to $M_W$. And the enhancement up to 5\%
is found in calculations of the second model. More strict restrictions to
parameters of 2-Higgs doublet model II are found.


title:
Field Transformations and the Classical Equation of Motion in Chiral
  Perturbation Theory

abstract:
  The construction of effective Lagrangians commonly involves the application
of the `classical equation of motion' to eliminate redundant structures and
thus generate the minimal number of independent terms. We investigate this
procedure in the framework of chiral perturbation theory. The use of the
'classical equation of motion' is interpreted in terms of field
transformations. Such an interpretation is crucial if one wants to bring a
given Lagrangian into a canonical form with a minimal number of terms. We
emphasize that the application of field transformations not only eliminates
structures, or, what is equivalent, expresses certain structures in terms of
already known different structures, but also leads to a modification of
coefficients of higher--order terms. This will become relevant, once one
considers effective interaction terms beyond next--to--leading order, i.e.,
beyond $O(p^4)$.


title: How Disoriented Chiral Condensates Form: Quenching vs. Annealing

abstract:
  We demonstrate that semiclassical fluctuations, their relaxation, and the
chiral phase transition are automatically incorporated in the numerical
simulations of the classical equations of motion in the linear $\sigma$-model
when longitudinal and transverse expansions are included. We find that domains
of disoriented chiral condensate with 4--5 fm in size can form through a quench
while an annealing leads to domains of smaller sizes. We also demonstrate that
quenching cannot be achieved by relaxing a chirally symmetric system through
expansion.


title: Cumulants of QCD Multiplicity Distributions in Small Phase Space Bins

abstract:
  It is shown that, as functions of their rank, cumulants of QCD multiplicity
distributions in small phase space bins possess the quasi- oscillating behavior
similar to that found for them in the total rapidity range. First minimum moves
to lower ranks for smaller bins. For the total rapidity range, it moves to
higher ranks with energy increase. The running property of the QCD coupling
constant is in charge of these effects which can be verified in experiment.


title: Fine Tuning in One-Higgs and Two-Higgs Standard Models

abstract:
  The fine-tuning principles are examined to predict the top-quark and
Higgs-boson masses. The modification of the Veltman condition based on the
compensation of vacuum energies is developed. It is implemented in the Standard
Model and in its minimal extension with two Higgs doublets. The top-quark and
Higgs-boson couplings are fitted in the SM for the lowest ultraviolet scale
where the fine-tuning can be stable under rescaling. It yields the low-energy
values $m_t \simeq 175 GeV; m_H \simeq 210 GeV$.


title: A General Supergravity Formalism for a Naturally Flat Inflaton Potential

abstract:
  A globally supersymmetric model of inflation will not work in a generic
supergravity theory because the higher order, nonrenormalisable supergravity
corrections destroy the flatness of the inflaton's potential. In this talk I
derive a form for the Kahler potential which eliminates these corrections if $
W = \partial W / \partial \varphi = \psi = 0 $ during inflation (where $W$ is
the superpotential, the inflaton is contained in $\varphi$, and $ \partial W /
\partial \psi \neq 0 $). I then point out that Kahler potentials of the
required form often occur in superstrings and that the target space duality
symmetries of superstrings often contain R-parities which would make $ W =
\partial W / \partial \varphi = 0 $ automatic for $\psi = 0$.


title: Light Quark Dependence of the Isgur-Wise Function from QCD Sum rules

abstract:
  We study light quark dependence of the Isgur-Wise function for
$B_a\rightarrow D_a$ and $B_a\rightarrow D^{*}_a$ in the framework of QCD sum
rules. At zero recoil , all the Isgur-Wise functions equal as required by heavy
quark symmetry and at non-zero recoil, the Isgur-Wise function for $B_s$ decay
falls faster than that for $B_{u,d}$ decay , which is just contrary to the
recent prediction of the heavy meson chiral perturbation theory. As
by-products, we also estimate SU(3) breaking effects in the mass and the decay
constant.


title:
The MSW solution to the solar neutrino problem for non-standard solar
  models

abstract:
  The difficulties for non-standard solar models (NSSM) in resolving the solar
neutrino problem are discussed stressing the incompatibility of the
gallium--Kamiokande data, and of the gallium--chlorine data. We conclude that
NSSM's cannot explain simultaneously the results of any two of the solar
neutrino data (chlorine, Kamiokande and gallium). We address further the
question whether the MSW solution exists for NSSM's (e.g. models with $^8$B
neutrino flux much lower than the standard one and/or central temperature $T_c$
very different from $T_c^{\text{SSM}}$). We demonstrate that the MSW solution
exists and is very stable relative to changes of $S_{17}$ ($S$-factor for $p$ +
$^7$Be reaction) and $T_c$. In particular, $\Delta m^2$ is almost constant
while $\sin^2 2\theta$ depends on the exact values of $S_{17}$ (or
$^8$B-neutrino flux) and $T_c$.


title:
Polarized twist-three distributions $g_T$ and $h_L$ and the role of
  intrinsic transverse momentum

abstract:
  In a nonstandard way we split up the polarized quark distributions $g_T$ and
$h_L$ into their twist-two, quark-mass, and interaction-dependent parts,
emphasizing the sensitivity to quark intrinsic transverse momentum. We show how
to derive the Burkhardt-Cottingham sum rule in this approach and derive a
similar sum rule for the chiral-odd distribution $h_2$. The effect of intrinsic
transverse momentum in experimental observables is illustrated in the
calculation of the ${\cal O}(1/Q)$ double-spin asymmetry $A_{LT}$ in Drell-Yan
scattering.


title:
Charm Quark Mass Dependence of QCD Corrections to Nonleptonic Inclusive
  B Decays

abstract:
  We calculate the radiative corrections to the nonleptonic inclusive B decay
mode $b\rightarrow c\bar u d$ taking into account the charm quark mass.
Compared to the massless case, corrections resulting from a nonvanishing c
quark mass increase the nonleptonic rate by (4--8)\%, depending on the
renormalization point. As a by--product of our calculation, we obtain an
analytic expression for the radiative correction to the semileptonic decay
$b\rightarrow u\tau\bar\nu$ taking into account the $\tau$ lepton mass, and
estimate the c quark mass effects on the nonleptonic decay mode $b\rightarrow
c\bar c s$.


title:
Reliability of the Estimation of CP Asymmetries for Nonleptonic $B^{0} -
  \bar{B}^{0}$ Decays into Non-CP-Eigen states

abstract:
  CP asymmetries for two-body-nonleptonic $B^{0} - \bar{B}^{0}$ decay into
non-CP-eigen states are calculated using two different methods: (i) Bauer,
Stech, and Wirbel factorization method to compute the decay amplitudes
directly; (ii) using $B^{0}, \bar{B}^{0}$ decay amplitude ratios to avoid the
direct computation of the decay amplitudes. The comparison of the results are
made. The conclusion is presented.


title: Additional Fermion Families and Precision Electroweak Data

abstract:
  The S,T, and U formalism for studying electroweak precision data has recently
been updated to include the effects of new light physics and within this
analysis the latest LEP and SLC data tightly constrain models of physics beyond
the Standard Model. We re-examine the constraints on additional strong and
weakly interacting fermion families in the light of these developments. We
conclude that the precision data favour models with at least one fermion with a
mass below 150GeV.


title: Multiplicity Distributions in QCD at Very High Energies

abstract:
  Recent results in QCD on multiplicity distributions are briefly reviewed. QCD
is able to predict very tiny features of multiplicity distributions which
demonstrate that the negative binomial distribution (and, more generally, any
infinitely divisible distribution) is inappropriate for precise description of
experimental data. New fits of high energy multiplicity distributions can be
derived.


title: Theoretical Study of the Electroweak Interaction -- Present and Future

abstract:
  There have been several important recent developments in precision
electroweak tests. These include: the new LEP energy scan during the 1993 run;
the first high-precision results on the left-right asymmetry from the SLD
Collaboration at SLAC; the probable discovery of the top quark by the CDF
Collaboration at Fermilab and the determination of its mass. I will discuss the
implications of these and earlier results for testing the standard model; for
the standard model parameters, including the top quark mass, the Higgs mass,
the weak mixing angle, and the strong coupling constant, $\alpha_s$; and the
search for new physics. In particular, given the CDF direct determination of
$m_t$ it is now possible to severely constrain certain types of new physics by
separating the contribution from new physics from the dependence on $m_t$.


title:
Pascal Program for Generating Tables of SU(3) Clebsch-Gordan
  Coefficients

abstract:
  Pascal routines are provided that generate representations of the group
$SU(3)$ and tabulate the Clebsch-Gordan coefficients in the products of
representations.


title: Compton Scattering by a Pion and off--Shell Effects

abstract:
  We consider Compton scattering by a pion in the framework of chiral
perturbation theory. We investigate off--shell effects in the s-- and
u--channel pole diagrams. For that purpose we perform a field transformation
which, in comparison with the standard Gasser and Leutwyler Lagrangian,
generates additional terms at order $p^4$ proportional to the lowest--order
equation of motion. As a result of the equivalence theorem the two Lagrangians
predict the same Compton scattering S--matrix even though they generate
different off--shell form factors. We conclude that off--shell effects are not
only model--dependent but also representation--dependent.


title:
On the relation between the fermion pole mass and MSbar Yukawa coupling
  in the standard model

abstract:
  We present the full one-loop correction to the relation between the running
MSbar Yukawa coupling, $\overline h_f(\mu)$, at some renormalization scale,
$\mu$, and the pole mass, $m_f$, of a fermion, $f$, in the standard model. Our
result complements previous analyses that included just the QCD correction to
this relation in the case of quarks. This allows us to convert, without loss of
information, the threshold value, $\overline h_f(m_f)$, of $\overline
h_f(\mu)$, which satisfies a renormalization-group equation and may be driven
up to some high-energy scale of new physics, to physical observables at low
energy. We investigate the limit of the Higgs boson and/or the top quark being
much heavier than all the other particles. We also list simple and yet rather
precise approximation formulae, which are convenient for applications.


title: Hierarchical Mass Matrices in a Minimal SO(10) Grand Unification II

abstract:
  We continue to investigate the minimal SO(10)xU(1)_H model which we proposed
recently. Renormalization group analysis of the model results in natural
predictions of quark-lepton masses and Kobayashi-Maskawa matrix along with
neutrino mixings adequate for solar neutrino oscillation.


title:
Implications of Horizontal Symmetries on Baryon Number Violation in
  Supersymmetric Models

abstract:
  The smallness of the quark and lepton parameters and the hierarchy between
them could be the result of selection rules due to a horizontal symmetry broken
by a small parameter. The same selection rules apply to baryon number violating
terms. Consequently, the problem of baryon number violation in Supersymmetry
may be solved naturally, without invoking any especially-designed extra
symmetry. This mechanism is efficient enough even for low-scale flavor physics.
Proton decay is likely to be dominated by the modes $K^+\bar\nu_i$ or
$K^0\mu^+(e^+)$, and may proceed at observable rates.


title:
Energy correlation and asymmetry of secondary leptons in $H\to t\bar t$
  and $H\to W^+W^-$

abstract:
  We study the energy correlation of charged leptons produced in the decay of a
heavy Higgs particle $H\to t\bar t\to bl^+\nu_l\bar bl^-\bar{\nu}_l$ and $H\to
W^+W^-\to l^+\nu_ll^-\bar{\nu}_l.$ The possible influence of $CP$--violation in
the $Ht\bar t$ and $HW^+W^-$ vertices on the energy spectrum of the secondary
leptons is analyzed. The energy distribution of the charged leptons in the
decay $H\to W^+W^-\to l^+\nu_ll^-\bar{\nu}_l$ is sensitive to the $CP$--parity
of the Higgs particle and yields a simple criterion for distinguishing scalar
Higgs from pseudoscalar Higgs.


title: Parton-Hadron Duality: Resonances and Higher Twists

abstract:
  We explore the physics of the parton-hadron duality in the nucleon structure
functions appearing in lepton-nucleon scattering. We stress that the duality
allows one to extract the higher-twist matrix elements from data in the
resonance region, and learn about the properties of resonances if these matrix
elements are known. As an example, we construct the moments of $F_2(x, Q^2)$
for the low and medium $Q^2$ region, and from which we study the interplay
between higher twists and the resonance contributions.


title: Low $Q^2$, Low $x$ Region in Electroproduction $-$ an Overview

abstract:
  We summarise existing experimental and theoretical knowledge on the structure
function $F_2$ in the region of low $Q^2$ and low $x$. The constraints on the
behaviour of structure functions in the limit $Q^2=0$ are listed.
Phenomenological low $Q^2$ parametrisations of the $F_2$ are collected and
their dynamical content is discussed. The high energy photoproduction and
nuclear shadowing are also briefly described. Recent update of the low $Q^2$,
low $x$ experimental data is given.


title: The Higgs Mass as the Discriminator of Electroweak Models

abstract:
  In the Minimal Supersymmetric Model (MSSM) and the Next to Minimal
Supersymmetric Model [(M+1)SSM], an upper bound on the lightest higgs mass can
be calculated. On the other hand, vacuum stability implies a lower limit on the
mass of the higgs boson in the Standard Model (SM). We find that a gap exists
for $m_t \stackrel{>}{\sim} 165$ GeV between the SM and both the MSSM and the
(M+1)SSM bounds. Thus, if the new top quark mass measurement by CDF remains
valid, a first measurement of the higgs mass will serve to exclude either the
SM or the MSSM/(M+1)SSM higgs sectors. In addition, we discuss Supersymmetric
Grand Unified Theories, other extentions of the SM, the discovery potential of
the lightest higgs, and the assumptions on which our conclusions are based.


title:
Renormalizing Coupled Scalars with a Momentum Dependent Mixing Angle in
  the MSSM

abstract:
  The renormalization of a system of coupled scalars fields is analyzed. By
introducing a momentum dependent mixing angle we diagonalize the inverse
propagator matrix at any momentum $p^2$. The zeros of the inverse propagator
matrix, \ie, the physical masses, are then calculated keeping the full momentum
dependence of the self energies. The relation between this method and others
previously published is studied. This idea is applied to the one-loop
renormalization of the CP-even neutral Higgs sector of the Minimal
Supersymmetric Model, considering top and bottom quarks and squarks in the
loops. Presented in the Eighth Meeting of the Division of Particles and Fields
of the American Physical Society ``DPF'94'', The University of New Mexico,
Albuquerque NM, August 2-6, 1994.


title:
Gravitino Decay into a Neutrino and a Sneutrino in the Inflationary
  Universe

abstract:
  Gravitino produced in the inflationary universe are studied. When the
gravitino decays into a neutrino and a sneutrino, the emitted high energy
neutrinos scatter off the background neutrinos and produce charged leptons
(mainly electrons and positrons), which cause the electro-magnetic cascades and
produce many soft photons. We obtain the spectra of the high energy neutrinos
as well as the spectrum of the high energy photon by integrating a set of
Boltzmann equations. Requiring these photons should not alter the abundances of
the light elements (D, $^3$He, $^4$He) in the universe, we can set the
stringent upperbound on the reheating temperature after the inflation. We find
that $T_R \lesssim (10^{10}-10^{12})$GeV for $m_{3/2}\sim (100\GEV - 1\TEV)$,
which is more stringent than the constraints in the previous works.


title: Non-universal Soft Scalar Masses in Superstring Theories

abstract:
  We study soft scalar masses comparing with gaugino masses in 4-dimensional
string models. In general non-universal soft masses are derived in orbifold
models. We give conditions on modular weights to lead to the large
non-universality in the soft scalar masses. This non-universality is applied to
the unification of the gauge coupling constants in the minimal string model.


title:
Threshold Pion Photo- and Electroproduction in Chiral Perturbation
  Theory

abstract:
  I present some recent results on neutral pion photo- and electroproduction in
the threshold region and discuss the low energy theorem for $E_{0+}$ and some
novel ones for the $P$-waves. I also study the two-pion production process
$\gamma N \to \pi \pi N$ from which complementary information can be gained.


title: False Vacuum Chaotic Inflation: The New Paradigm?

abstract:
  Recent work is reported on inflation model building in the context of
supergravity and superstrings, with special emphasis on False Vacuum (`Hybrid')
Chaotic Inflation. Globally supersymmetric models do not survive in generic
supergravity theories, but fairly simple conditions can be formulated which do
ensure successful supergravity inflation. The conditions are met in some of the
versions of supergravity that emerge from superstrings.


title: W Plus Heavy Quark Production at the Tevatron

abstract:
  We summarize the motivations for and the status of the calculation of the $W
+$ heavy quark production process in $p \bar p$ colliders to Next-to-Leading
Order in QCD. This process can be used to constrain the strange quark
distribution function at high $Q^2$ at the Tevatron, and also to study the
bottom content of $W+1$~jet events. In addition, when crossed, the calculation
essentially describes the single top quark production process to
Next-to-Leading Order in QCD.


title: Stranger in the Light: The Strange Vector Form Factors of the Nucleon

abstract:
  A model combining vector meson dominance, $\omega - \phi$ mixing and a kaon
cloud contribution is used to estimate the strangeness vector form factors of
the nucleon in the momentum range of the planned measurements at MIT-Bates and
CEBAF. We compare our results with some other theoretical estimates and discuss
the nucleon strangeness radius in models based on dynamically dressed, extended
constituent quarks. For a quantitative estimate in the latter framework we use
the Nambu-Jona-Lasinio model.


title: Can an Infrared-vanishing Gluon propagator Confine Quarks?

abstract:
  It is shown that the solution of the quark Dyson-Schwinger equation in QCD
obtained with a gluon propagator of the form $D(q) \sim q^2/[q^4+b^4]$ and a
quark-gluon vertex that is free of kinematic singularities does not describe a
confined particle and that there is always a value of $b^2 = b^2_c$ such that
chiral symmetry is not dynamically broken for $b^2>b_c^2$.


title: A Precise Determination of $\alpha_s$ from Lattice QCD

abstract:
  We present a new determination of the QCD strong coupling constant based on
precise lattice calculations of the $\Upsilon$ spectrum. The largest systematic
uncertainty in previous such determinations resulted from the absence of vacuum
polarization from light quarks. We substantially reduce this error by including
two flavors of dynamical light quarks and extrapolating to three. We find
$\alphathree_\V(8.2~\GeV) = 0.196(3)$ for three light flavors, corresponding to
$\alphafive_\msbar(M_Z) = 0.115(2)$. This is significantly more accurate than
previous determinations using this or any other technique.


title: Is a Light Gluino Compatible with N=1 Supersymmetry?

abstract:
  Using the new CLEO bound on the branching ratio of the decay mode
$b\longrightarrow s\gamma$ given by $1\times10^{-4}< B(b\longrightarrow
s\gamma)<4\times10^{-4}$ at 95\% c.l., and the experimental bounds on the
masses of the lightest chargino, the second lightest neutralino, and the light
CP-odd Higgs, we find that a light gluino is incompatible with a class of
supergravity models defined by $N=1$ supergravity, with a radiatively broken
electroweak symmetry group and universality of scalar and gaugino masses at the
unification scale. We also find in this scenario strong constraints on the
parameter space due to the new CLEO bounds on $B(b\longrightarrow s\gamma)$.
Presented in the International Workshop ``SUSY-94'', University of Michigan,
Ann Arbor MI, May 14-17, 1994.


title: The $D^0\bar{D}^0$ Mixing Search --- Current Status and Future Prospects

abstract:
  The search for $D^0\bar{D}^0$ mixing carries a large discovery potential for
new physics since the $D^0\bar{D}^0$ mixing rate is expected to be very small
in the Standard Model. The past decade has seen significant experimental
progress in sensitivity, from 20\% down to 0.37\%. This paper discusses the
techniques, current experimental status, and future prospects for the mixing
search. Some new ideas, applicable to future mixing searches, are introduced.
One of the new ideas is to use Singly Cabibbo Suppressed Decays (SCSD), such as
$D^0 \to K+K-, \pi^+\pi^-$, to study mixing. A postscript version will be
available through World-Wide-Web in http://w4.lns.cornell.edu/public/TALK/1994
soon.


title:
{$SU(3)$} breaking in {$\bar{B}/D\rar Kl\bar \nu$} decays and value of
  {$V_{cd}/V_{cs}$}}

abstract:
  We determine the $SU(3)$-breaking effects in the $\bar{B}/D \rar Kl\bar \nu$
decays from the ratio of the $\bar{B}/D\rar Kl\bar \nu$ over the $\bar{B}/D
\rar \pi l\bar \nu$ semileptonic form factors using a {\it semi-analytic}
expression based on QCD spectral sum rules. We obtain $f_+^{\bar{B}\rar
K}(0)/f_+^{\bar{B} \rar \pi}(0)$ = $1.007\pm 0.020$ and $f_+^{D\rar
K}(0)/f_+^{D \rar \pi}(0)$ = $1.102 \pm 0.007$, which combined with the present
CLEO data, leads to $V_{cd}/V_{cs}$ = $ 0.323 \pm 0.058$ and then, to: $\vert
V_{cs}\vert = 0.72\pm 0.10$. The prediction on the ratio of mixing angle is
(surprisingly) much higher than the value $0.226 \pm 0.004$ derived from the
unitarity constraint on the CKM matrix, while the corresponding value of $
V_{cs}$ is lower. These results can open a window for new physics, though a
stringent conclusion needs data with much higher statistics (from e.g tau-charm
factory) or/and alternative QCD-based estimates of the ratio of the
semileptonic form factors.


title:
Implications of the Top Quark Mass Measurement for the CKM Parameters,
  $x_s$ and CP Asymmetries

abstract:
  Motivated by the recent determination of the top quark mass by the CDF
collaboration, $\mt =174 \pm 10 ^{+13}_{-12}$ GeV, we review and update the
constraints on the parameters of the quark flavour mixing matrix $V_{CKM}$ in
the standard model. In performing our fits, we use inputs from the measurements
of the following quantities: (i) $\abseps$, the CP-violating parameter in $K$
decays, (ii) $\delmd$, the mass difference due to the \bdbdbar\ mixing, (iii)
the matrix elements $\absvcb$ and $\absvub$, and (iv) $B$-hadron lifetimes. We
find that the allowed region of the unitarity triangle is very large, mostly
due to theoretical uncertainties. (This emphasizes the importance of
measurements of CP-violating rate asymmetries in the $B$ system.) Nevertheless,
the present data do somewhat restrict the allowed values of the coupling
constant product $f_{B_d}\sqrt{\hat{B}_{B_d}}$ and the renormalization-scale
invariant bag constant $\hat{B}_K$. With the updated CKM matrix we present the
currently-allowed range of the ratio $\vert V_{td}/V_{ts} \vert$, as well as
the standard model predictions for the \bsbsbar\ mixing parameter $\xs$ and the
quantities $\sin 2\alpha$, $\sin 2\beta$ and $\sin^2\gamma$, which characterize
the CP-asymmetries in $B$-decays. The ALEPH collaboration has recently reported
a significant improvement on the lower limit on the $\bs$-$\bsb$ mass
difference, $\Delta M_s/\Delta M_d > 11.3$ (95\% C.L.). This has interesting
consequences for the CKM parameters which are also worked out.
  NOTE: this is a revised and updated version of our previous paper.


title:
Custodial nonabelian gauge symmetries in realistic superstring derived
  models

abstract:
  A well known problem in supersymmetric models is the presence of, lepton and
baryon number violating, dimension four operators. The traditional R parity
solution may not be suitable if one tries to incorporate supersymmetry into a
Planck scale theory. I propose a different solution in the context of realistic
string models. I show that realistic string models can give rise to custodial
nonabelian gauge symmetries under which only the leptons or quarks transform. I
explain how such symmetries arise in a class of free fermionic models that are
based on $Z_2\times Z_2$ orbifold with standard embedding. The custodial
symmetries forbid proton decay from dimension four operators while allowing R
parity violation.


title: SUSY Contributions to the Z--->3 Photon Decay

abstract:
  In this talk I comment on the contributions of all three types of particles
(scalars, fermions and bosons) to the three--photon Z decay within the standard
model (SM) and its extensions to the 2 Higgs doublet model (2 HDM) and the
minimal supersymmetric extension of the standard model (MSSM). I also comment
briefly on the charginos contribution to this decay rate. Finally I comment on
the fermions and scalars contributions to the three--gluon Z decay.


title: SUSY QCD Corrections to the t-->H+b Decay

abstract:
  In this talk I present the contribution of gluinos and scalar quarks to the
decay rate of the top quark into a charged Higgs boson and a bottom quark
within the minimal supersymmetric standard model, including the mixing of the
scalar partners of the left- and right-handed top quark.


title: SU(2)-Flavor-Symmetry Breaking in Nuclear Antiquark Distributions

abstract:
  SU(2)-flavor-symmetry breaking in antiquark distributions of the nucleon was
suggested by the New Muon Collaboration (NMC) in deep inelastic muon
scattering. As an independent test, Drell-Yan data for the tungsten target have
been used for examining the asymmetry. We investigate whether there exists
significant modification of the $\bar u -\bar d$ distribution in nuclei in a
parton recombination model. It should be noted that a finite $\bar u-\bar d$
distribution is theoretically possible in nuclei even if the sea is $SU(2)_f$
symmetric in the nucleon. In neutron-excess nuclei such as the tungsten, there
exist more $d$-valence quarks than $u$-valence quarks, so that more $\bar
d$-quarks are lost than $\bar u$-quarks are due to parton recombinations in the
small $x$ region. Our results suggest that the nuclear modification in the
tungsten is a 2--10 % effect on the $\bar u-\bar d$ distribution suggested by
the NMC data. Nuclear effects on the flavor asymmetric distribution could be an
interesting topic for future theoretical and experimental investigations.


title: Threshold Multiparticle Amplitudes in Phi^4 Theories at Large N

abstract:
  I review some recent work on the problem of multiparticle production in a
phi^4-theory with an O(N) symmetry. Threshold amplitudes with fixed number of
produced particles are exactly calculated at large-N to all loops and vanish on
mass shell for 2->n when n>2 due to a dynamical symmetry. I consider an
extension to the cases when the O(N) symmetry is softly broken by masses
including spontaneous breaking of a remaining reflection symmetry. The exact
solutions are obtained by the Gelfand--Dikii technique of finding the diagonal
resolvent of the Schrodinger operator which emerges due to factorization at
large N. I report also some new results on the diagonal resolvent for a general
Poschl--Teller potential, which could be useful for calculations of
multiparticle amplitudes in the standard model.


title: Heavy Quarkonium in the dual Ginzburg-Landau theory of QCD

abstract:
  We study the masses and the leptonic decay widths of heavy quarkonium in the
dual Ginzburg-Landau (DGL) theory of QCD, in which the abelian monopole
condensation plays an essential role for color confinement. The effect of color
screening due to the light quark pair creation is introduced by the infrared
momentum cutoff in the gluon propagator. We find that the color screening
effect is important to reproduce the properties of the heavy quarkonium, in
particular the leptonic decay width. We also discuss the underlying systematics
of the heavy quark spectroscopy in the DGL theory.


title: Electroweak Baryogenesis from a Classical Force

abstract:
  We describe a new effect which produces baryons at a first order electroweak
phase transition. It operates when there is a CP-violating field present on
propagating bubble walls. The novel aspect is that it involves a purely
classical force, which alters the motion of particles across the wall and
through diffusion creates a chiral asymmetry in front of the wall. We develop a
technique for computing the baryon asymmetry using the Boltzmann equation, and
a fluid approximation which allows us to model strong scattering effects. The
final formula for the baryon asymmetry has a remarkably simple form.


title:
Diffractive Photoproduction of Jets with a Direct Pomeron Coupling at
  HERA

abstract:
  We investigate in detail the effect of a direct pomeron coupling to quarks on
the production of jets in $ep$ scattering with almost real photons. Jet
production via a direct pomeron coupling is compared with the resolved--pomeron
mechanism. We consider both direct and resolved photoproduction. Rapidity and
transverse momentum distributions are calculated and compared with preliminary
H1 and ZEUS data.


title:
Renormalization of four-quark operators, effective theory, and the role
  of evanescent operators

abstract:
  We present, in the context of dimensional regularization, a prescription to
renormalize Feynman diagrams with an arbitrary number of external fermions.
This prescription, which is based on the original t'Hooft-Veltman proposal to
keep external particles in four dimensions, is particularly useful to define
the 'renormalization' (in the context of effective Lagrangian) of physical
four-quark operators without introducing any evanescent operator. The results
obtained for $b\rightarrow s$ processes agree with those from the so-called
naive prescription, but disagree with the ones with the introduction of
evanescent operators in a renormalization group analysis. We also present an
explicit two loop calculation of the mixing of the evanescent operators with
the physical dimension five operators for the same processes. Particular
attention is paid to the unboundedness nature of such mixing and how a formal
finite transformation is effected to decouple. The inevitable mass dependence
of one of these schemes in the literature is pointed out as the cause for the
difference mentioned.


title: Higher-Order Lipatov Kernels and the QCD Pomeron

abstract:
  Three closely related topics are covered. The derivation of $O(g^4)$ Lipatov
kernels in pure glue QCD. The significance of quarks for the physical Pomeron
in QCD. The possible inter-relation of Pomeron dynamics with Electroweak
symmetry breaking.


title:
Estimate of Quantum corrections to the Mass of the Chiral Soliton in the
  Nambu--Jona--Lasinio Model

abstract:
  The Bethe--Salpeter equation for pion fluctuations off the chiral soliton in
the Nambu--Jona--Lasinio model is constructed. By Goldstone's theorem this
equation has rotational and translational zero modes because the classical
soliton is a localized stationary field configuration which violates rotational
and translational invariance. Furthermore, the proper normalization of the
fluctuating eigen--modes is obtained. Second quantization of the pion
fluctuations off the chiral soliton provides an energy functional of the pion
fluctuations which formally coincides with that of a harmonic oscillator. The
corresponding quantum corrections to the soliton mass together with the
semi--classical cranking prescription yield reasonable predictions for the
masses of the nucleon and the $\Delta$--resonance when the constituent quark
mass is chosen to be about 400MeV. These calculations are, to some extend,
hampered by the non--confining character of the Nambu--Jona--Lasinio model.
Comments on the $1/N_C$ counting scheme are added.


title: The LPM effect in QCD and Radiative energy loss in a quark-gluon plasma

abstract:
  The non-abelian analog of the Landau-Pomeranchuk-Migdal effect is
investigated in perturbative QCD. Extending our previous studies, the
suppression of induced soft bremsstrahlung due to multiple scatterings of
quarks in the spinor representation is considered. The effective formation time
of gluon radiation due to the color interference is shown to depend on the
color representation of the emitting parton, and an improved formula for the
radiative energy loss is derived that interpolates between the factorization
and Bethe-Heitler limits.


title: Experimental consequences of one-parameter no-scale supergravity models

abstract:
  We consider the experimental predictions of two {\em one-parameter} no-scale
$SU(5)\times U(1)$ supergravity models with string-inspired moduli and dilaton
seeds of supersymmetry breaking. These predictions have been considerably
sharpened with the new information on the top-quark mass from the Tevatron, and
the actual measurement of the $B(b\to s\gamma)$ branching ratio from CLEO. In
particular, the sign of the Higgs mixing parameter $\mu$ is fixed. A more
precise measurement of the top-quark mass above (below) $\approx160\GeV$ would
disfavor the dilaton (moduli) scenario. Similarly a measurement of the lightest
Higgs-boson mass above 90 GeV (below 100 GeV) would disfavor the dilaton
(moduli) scenario. At the Tevatron with $100\ipb$, the reach into parameter
space is significant only in the dilaton scenario ($m_{\chi^\pm_1}\lsim80\GeV$)
via the trilepton and top-squark signals. At LEPII the dilaton scenario could
be probed up the kinematical limit via chargino and top-squark pair production,
and the discovery of the lightest Higgs boson is guaranteed. In the moduli
scenario only selectron pair production looks promising. We also calculate the
supersymmetric contribution to the anomalous magnetic moment of the muon.


title:
Extension of the Chiral Perturbation Theory Meson Lagrangian to Order
  $P^6$

abstract:
  We have derived the most general chirally invariant Lagrangian ${\cal L}_6$
for the meson sector at order $p^6$. The result provides an extension of the
standard Gasser-Leutwyler Lagrangian ${\cal L}_4$ to one higher order,
including as well all the odd intrinsic parity terms in the Lagrangian. The
most difficult part of the derivation was developing a systematic strategy so
as to get all of the independent terms and eliminate the redundant ones in an
efficient way. The 'equation of motion' terms, which are redundant in the sense
that they can be transformed away via field transformations, are separated out
explicitly. The resulting Lagrangian has been separated into groupings of terms
contributing to increasingly more complicated processes, so that one does not
have to deal with the full result when calculating $p^6$ contributions to
simple processes.


title: Dimensional Reduction for Fermions

abstract:
  We generalize the concept of dimensional reduction to operators involving
fermion fields in high temperature field theories. It is found that the
ultraviolet behavior of the running coupling constant plays a crucial role. The
general concept is illustrated explicitly in the Gross-Neveu model.


title:
Exact Sum Rules at Finite Temperature and Chemical Potential and their
  Application to QCD

abstract:
  Within the framework of the operator product expansion (OPE) and the
renormalization group equation (RGE), we show that the temperature and chemical
potential dependence of the zeroth moment of a spectral function (SF) in an
asymptotically free theory is completely determined by the one-loop structure
of the theory. This exact result constrains the qualitative shape of SF's, and
implies striking phenomenological effects near phase transitions.


title: Status of the Standard Model

abstract:
  The standard model of electroweak interactions is reviewed, stressing the top
quark's impact on precision tests and on determination of parameters of the
Cabibbo-Kobayashi-Maskawa (CKM) matrix. Some opportunities for the study of CP
violation in the decays of $b$-flavored mesons are mentioned, and the
possibility of a new ``standard model'' sector involving neutrino masses is
discussed.


title:
Infrared effects and the asymptotics of perturbation theory in weak
  decays of heavy particles

abstract:
  I discuss the interplay of infrared sensitivity in large order perturbative
expansions with the presence of explicit nonperturbative corrections in the
context of heavy quark expansions. The main focus is on inclusive decays and
the status of the kinetic energy of the heavy quark. This talk summarizes work
done with Braun and Zakharov.


title: Recalculation of QCD Corrections to $b \to s \gamma$ Decay

abstract:
  We give a more complete calculation of $b \to s\gamma $ decay, including
leading log QCD corrections from $m_{top}$ to $M_W$ in addition to corrections
from $M_{W}$ to $m_b$. We have included the full set of dimension-6 operators
and corrected numerical mistakes of anomalous dimensions in a previous
paper\cite{Cho}. Comparing with the calculations without QCD running from
$m_{top}$ to $M_W$\cite{Mis}, the inclusive decay rate is found to be enhanced.
At $m_t=150$GeV, it results in 12\% enhancement, and for $m_t=250$GeV, 15\% is
found. The total QCD effect makes an enhanced factor of 4.2 at $m_t=150$GeV,
and 3.2 for $m_t=250$GeV.


title: Gluon fragmentation into polarized charmonium

abstract:
  Gluon fragmentation to $\chicJ(1P)$ followed by single photon emission
represents the dominant source of prompt $J/\Psi$'s at the Tevatron for
$p_\perp \gtap 6 \GeV$. Since fragmenting gluons are approximately transverse,
their products are significantly polarized. We find that gluon fragmentation
populates the helicity levels of $\chione$, $\chitwo$ and $J/\Psi$ according to
$D_{\chione^{(h=0)}}: D_{\chione^{(|h|=1)}} \simeq 1:1$, $D_{\chitwo^{(h=0)}} :
D_{\chitwo^{(|h|=1)}} : D_{\chitwo^{(|h|=2)}} \simeq 1:2.9:6.0$ and
$D_{\J^{(h=0)}} : D_{\J^{(|h|=1)}} \simeq 1:3.4$. We also speculate that gluon
fragmentation to the radially excited $\chitwo(2P)$ state followed by
subsequent radiative decay could represent a large source of $\psi'(2S)$'s and
potentially resolve the $\psi'$ deficit problem. A measurement of these states'
polarizations would test this idea.


title: More on the Burkhardt-Cottingham Sum Rule in QCD

abstract:
  The QCD higher order effects to the polarized structure function $g_2(x, Q^2
)$ are reanalyzed for massive quarks in the context of the operator product
expansion. We confirm that the lowest moment of $g_2 (x, Q^2 )$ which
corresponds to the Burkhardt-Cottingham sum rule does {\sl not} suffer from
radiative corrections in perturbative QCD.


title: Spin Structure Function $g_2$ and Twist-3 Operators in QCD

abstract:
  We investigate the spin structure function $g_2 (x, Q^2 )$ in the framework
of the operator product expansion and the renormalization group. The twist-3
operators appearing in QCD are examined and their relations are studied. It is
noted that operators proportional to equation of motion appear in the operator
mixing through renormalization, which can be studied from the relevant Green's
functions. We also note that the coefficient functions can be properly fixed
after the choice of independent operators.


title:
Connected Green function approach to ground state symmetry breaking in
  $\Phi^4_{1+1}$-theory

abstract:
  Using the cluster expansions for n-point Green functions we derive a closed
set of dynamical equations of motion for connected equal-time Green functions
by neglecting all connected functions higher than $4^{th}$ order for the
$\lambda \Phi^4$-theory in $1+1$ dimensions. We apply the equations to the
investigation of spontaneous ground state symmetry breaking, i.e. to the
evaluation of the effective potential at temperature $T=0$. Within our momentum
space discretization we obtain a second order phase transition (in agreement
with the Simon-Griffith theorem) and a critical coupling of
$\lambda_{crit}/4m^2=2.446$ as compared to a first order phase transition and
$\lambda_{crit}/4m^2=2.568$ from the Gaussian effective potential approach.


title: Chiral Dynamics, Deconfinement and Thermal Dileptons

abstract:
  We show that in a hot hadron gas, chiral symmetry restoration and
deconfinement lead to a strong suppression of dilepton production by pion
annihilation in the continuum above the $\rho-\omega-\phi$ peak. The
suppression due to deconfinement persists also for annihilation reactions
involving heavier mesons.


title:
New solution for dynamical symmetry breaking with top and bottom quark
  condensates

abstract:
  Starting from a general $\rm SU_2\times U_1$ invariant interaction Lagrangian
${\cal L}_{\rm int}$ with four-fermion interactions between top $t$ and bottom
$b$ quarks and working in the bubble approximation, we get a single Higgs as a
bound state of quark pairs by allowing both $\langle \bar tt\rangle$ and
$\langle\bar bb\rangle$ to be nonzero and the $t$ and $b$ states to mix. We
find relations between the three four-fermion couplings $g_t, g_b,$ and
$g_{tb}$ and show the new result that they may all be finite, with $g\Lambda
^2\gg1$, where $\Lambda$ is the cutoff. Thus the dimensionless couplings $g' =
g\Lambda ^2$ correspond to strong interactions. Previous work with either one
or more quark condensates found a fine-tuning condition giving $g\Lambda
^2\sim$ O($1$). The Higgs mass $m_H$ is approximately the single-vev value
$m_H\approx 2m_t$, and the quark mass ratio is $m_t/m_b\approx g_b/g_{tb}$.
There is a new symmetry of ${\cal L}_{\rm int}$, corresponding to a flat
direction in the space of composite states. Breaking this symmetry by turning
on one small eigenvalue of the coupling matrix turns on the quark masses and
introduces the massive Higgs state, so that $m_b,m_t,m_H\ll \Lambda$ is
natural.


title:
Phenomenological Determination of the Beauty Meson Decay Parameter $f_B$
  and the CP-Violating Angle $\delta$

abstract:
  We fit the ${\cal CKM}$-matrix to all recent data with the following free
parameters: three mixing angles, the CP-violating angle $\delta$ in the Maiani
parametrisation, the top quark mass $m_t$, and the product $f_B{\cal
B}_{\B}^{1/2}$, where $f_B$ is the $B$-meson decay parameter and ${\cal
B}_{\B}$ is the bag parameter. Our fits span a contiguous region in the
$(f_B{\cal B}_{\B}^{1/2},\ \cos\delta)$--plane, limited by $0.117\lsim f_B{\cal
B}_{\B}^{1/2}/{\rm GeV}\lsim 0.231$ and --0.95 $\lsim$ $\cos\delta$ $\lsim$
0.70. The parameters $f_B{\cal B}_{\B}^{1/2}$ and $\cos\delta$ are strongly
positively correlated.


title:
Determination of Fundamental Supersymmetry Parameters from Chargino
  Production at Lepii

abstract:
  If accessible at LEP II, chargino production is likely to be one of the few
available supersymmetric signals for many years. We consider the prospects for
the determination of fundamental supersymmetry parameters in such a scenario.
The study is complicated by the dependence of observables on a large number of
these parameters. We propose a straightforward procedure for disentangling
these dependences and demonstrate its effectiveness by presenting a number of
case studies at representative points in parameter space. Working in the
context of the minimal supersymmetric standard model, we find that chargino
production by itself is a fairly sensitive probe of the supersymmetry-breaking
sector. For significant regions of parameter space, it is possible to test the
gaugino mass unification hypothesis and to measure the gaugino contents of the
charginos and neutralinos, thereby testing the predictions of grand unification
and the viability of the lightest supersymmetric particle as a dark matter
candidate. For much of the parameter space, it is also possible to set limits
on the mass of the electron sneutrino, which provide a valuable guide for
future particle searches.


title: Lambda(1405) in the Bound State Soliton Model

abstract:
  The strong and electromagnetic properties of the Lambda(1405) hyperon are
studied in the framework of the bound state soliton model. We explicitly
evaluate the strong coupling constant g(Lambda^*-N-K), the Lambda^* magnetic
moment, mean square radii and radiative decay amplitudes. The results are shown
to be in general agreement with available empirical data. A comparison with
results of other models is also presented.


title:
Single Spin Asymmetry of Vector Meson Production as a Probe of Asymmetry
  of Parton Scattering

abstract:
  Azimuthal asymmetry of vector-meson production in single-transversely
polarized proton-proton collisions ($p\up p$) is calculated in the string model
of particle production. The asymmetry is generated only during fragmentation of
a high-energy quark into hadrons. The obtained asymmetry of the $\rho^\pm$ is
opposite in sign to that of $\pi^\pm$ mesons. On the other hand, an asymmetry
appearing during parton scattering would contribute with the same sign to that
of vector and pseudoscalar mesons. Thus, a combined measurement of both can be
used to estimate the contribution to the asymmetry from parton scattering.


title: Dips in Partial Wave Amplitudes from Final State Interactions

abstract:
  We consider the dip-peak structures in the J=0 partial wave amplitudes for
processes $\gamma\gamma\rightarrow W^+W^-~
\mbox{and}~\gamma\gamma,gg\rightarrow t\overline{t}$ taking into account the
corresponding Born term process and the rescattering process where the
intermediate state is rescattered through the exchange of Higgs resonance state
in the direct channel.


title: Polarised parton distributions

abstract:
  We analyze spin dependent parton distributions consistent with the most
recent measurements of the spin dependent deep inelastic scattering structure
functions and obtained in the framework of the spin dilution model. Predictions
for the doubly polarised proton-proton Drell-Yan asymmetry, for the high
$p_{T}$ photon production mechanism and $J/\Psi$ excitation are calculated
using these distributions and are shown to be particularly adequate to unveil
the polarisation of partons in the proton.


title:
New Universality of Baryon Isgur--Wise Form Factor in the Large $N_c$
  limit

abstract:
  New universality appears for the baryon Isgur--Wise form factor in the large
$N_c$ limit. It is found that the semileptonic $\Lambda_b \rightarrow
\Lambda_c$ and $\Sigma_b^{(*)} \rightarrow \Sigma^{(*)}_c$ decays are described
by the same form factor, which can be calculated analytically. In the exact
chiral $SU(3)$ limit, the same form factor is applicable to semileptonic
$\Omega_b^{(*)} \rightarrow \Omega^{(*)}_c$ decays.


title:
SMATASY - A program for the model independent description of the Z
  resonance

abstract:
  SMATASY is an interface for the ZFITTER package and may be used for the model
independent description of the Z resonance at LEP 1 and SLC. It allows the
determination of the Z mass and width and its resonance shape parameters r and
j for cross-sections and their asymmetries. The r describes the peak height and
j the interference of the Z resonance with photon exchange in each scattering
channel and for $\sigma_T$, $\sigma_{FB}$, $\sigma_{lr}$, $\sigma_{pol}$ etc.
separately. Alternatively, the helicity amplitudes for a given scattering
channel may be determined. We compare our formalism with other model
independent approaches. The model independent treatment of QED corrections in
SMATASY is applicable also far away from the Z peak.


title:
Order $\alpha_s^{2}$ contributions to the Drell-Yan cross section at
  fixed target energies

abstract:
  {}From the literature one infers that the bulk of the order $\alpha_{s}$
corrections to the Drell-Yan cross sections $d\sigma/dm$ and
$m^{3}d^{2}\sigma/dmdx_{F}$ is constituted by the soft plus virtual gluon part
of the coefficient function. In the case of $d\sigma/dm$ it can be shown that
at fixed target energies the effect of the exact order $\alpha_{s}^{2}$
corrected coefficient function is very well approximated by its soft plus
virtual gluon part. Since the complete order $\alpha_{s}^{2}$ contribution to
the coefficient function is missing we have to assume that the same
approximation also holds for $m^{3}d^{2}\sigma/dmdx_{F}$. It appears that the
discrepancy between the exact order $\alpha_{s}$ corrected cross section and
the massive lepton pair data taken at fixed target experiments can be partially
explained by including the order $\alpha_{s}^{2}$ soft plus virtual gluon part
of the coefficient function.


title: Heavy Sterile Neutrinos and Neutrinoless Double Beta Decay

abstract:
  We investigate the possibility of producing neutrinoless double beta decay
without having an electron neutrino with a mass in the vicinity of 1 eV. We do
so by having a much lighter electron neutrino mix with a much heavier (m > 1
GeV) sterile neutrino. We study the constraints on the masses and mixings of
such heavy sterile neutrinos from existing laboratory, astrophysical and
cosmological information, and discuss the properties it would require in order
to produce a detectable signal in current searches for neutrinoless double beta
decay.


title: An Effective Chiral Meson Lagrangian at $O(P^6)$ from the NJL Model

abstract:
  In this work we present a strong chiral meson Lagrangian up to and including
$O(p^6)$ in the momentum expansion. It is derived from the Nambu--Jona-Lasinio
(NJL) model using the heat-kernel method. Identities related to the properties
of covariant derivatives of the chiral matrix $U$ as well as field
transformations have been used to obtain a minimal set of linearly independent
terms.


title: Baryon Number Transport in a Cosmic QCD-Phase Transition

abstract:
  We investigate the transport of baryon number across phase boundaries in a
putative first order QCD-phase transition. Two independent phenomenological
models are employed to estimate the baryon penetrability at the phase boundary:
chromoelectric flux tube models; and an analogy to baryon-baryon coalescence in
nuclear physics. Our analysis indicates that baryon transport across phase
boundaries may be order of magnitude more efficient than other work has
suggested. We discuss the substantial uncertainties involved in estimating
baryon penetrability at phase boundaries.


title: Uncertainties from Long Range Effects in $B \to K^* \gamma

abstract:
  We reconsider the `long-range' component of the radiative transition $B \to
K^* \gamma$. A careful analysis of the vector dominance amplitude $B \to V_1
V_2 \to V_1 \gamma$ is carried out, with emphasis on the role of gauge
invariance. The procedure for incorporating phenomenological $B\to V_1 V_2$
data is identified and polarization data, only recently available, is employed
to estimate the magnitude of the vector dominance effect. We summarize
uncertainties in the $B\to K^*\gamma$ radiative transition produced by
long-range effects and provide sugggestions for further experimental work.


title:
Polarization as a Probe to the Production Mechanisms of Charmonium in
  $\pi N$ Collisions

abstract:
  Measurements of the polarization of $\jp$ produced in pion-nucleus collisions
are in disagreement with leading twist QCD prediction where $\jp$ is observed
to have negligible polarization whereas theory predicts substantial
polarization. We argue that this discrepancy cannot be due to poorly known
structure functions nor the relative production rates of $\jp$ and $\chi_J$.
The disagreement between theory and experiment suggests important higher twist
corrections, as has earlier been surmised from the anomalous non-factorized
nuclear $A$-dependence of the $\jp$ cross section.


title: Anomalous Charm Production at Large $x_{F}$

abstract:
  We show that the new QCD production mechanisms which were proposed by S. J.
Brodsky, P. Hoyer, A. H. Mueller and the author can explain at least some of
the anomalous behavior of open and/or closed charm production at large $x_{F}$.


title: Feasibility of Extracting V_td from Radiative B(B_s) Decays

abstract:
  We use existing measurements of $D^-\to K^{\ast0}\rho^-$ and $B\to
\psi+K^\ast$, coupled with flavor independence of QCD, and with vector meson
dominance to show that long distance contributions to $B\to \rho +\gamma$ are
potentially very serious. We note that long distance (LD) contributions can be
appreciably different in $B^-\to \rho^-+\gamma$ and $B^0\to \rho^0 (\omega)
+\gamma$. All radiative decays of $B$, $B_S$ are shown to be governed
essentially by two LD and two short-distance (SD) hadronic entities. Separate
measurements of $B^-\to \rho^-+\gamma$, $B^0\to \rho^0 (\omega) +\gamma$, along
with $B\to K^\ast +\gamma$ appear necessary for a meaningful extraction of
\vtd. Measurements of $B_S\to \phi+\gamma$ and $K^{\ast0}+\gamma$ could also
provide very useful consistency checks.


title: Pion Observables and QCD

abstract:
  The nonperturbative, Dyson-Schwinger equation approach to solving QCD
provides a straightforward, microscopic description of dynamical chiral
symmetry breaking and confinement. It is an ideal tool for the study of pion
observables. This is illustrated via its application to the calculation of: the
$\pi$-$\pi$ scattering lengths $a_0^0$, $a_0^2$, $a_1^1$, $a_2^0$, $a_2^2$ and
associated partial wave amplitudes; the $\pi^0\rightarrow \gamma\gamma$ decay
width; and the charged pion form factor, $F_\pi(q^2)$.


title:
The effect of new physics on R_b = \Gamma(Z->b bbar) /
  \Gamma(Z->hadrons)

abstract:
  Motivated by the $\sim 2\sigma$ discrepancy between the experimental value
for $R_b$ and the theoretical prediction of the Standard Model, we examine the
effect of new physics on the $Z$-$b$-$\overline{b}$ vertex. Using general
results for both new scalars and gauge bosons, we show that two conditions must
be satisfied in order for new physics to give observable deviations in the
vertex. In particular, the fermion in the loop must transform chirally under
$SU(2)\times U(1)$ and it must be massive compared to the exchanged boson. We
examine the implications of these results on the 2 Higgs Doublet model and the
Left-Right Symmetric model.


title: A fresh look into the heavy quark-mass values

abstract:
  Using the recent {\it world average} $\alpha_s(M^2_Z)= 0.118 \pm 0.006$, we
give the {\it first direct extraction} from the $\Psi$ and $\Upsilon$ data of
the values of the {\it running heavy quark masses} within QCD spectral sum
rules to two-loops in the $\overline {MS}$-scheme: $\mr_b(M^{PT2}_b)$ =
$(4.23~^{+0.03}_{-0.04} \pm 0.02)$ GeV and $\mr_c(M^{PT2}_c)$ = $(1.23~^{+
0.02}_{-0.04} \pm 0.03)$ GeV, (the errors are respectively due to $\alf$ and to
the gluon condensate), and the corresponding value of the {\it short-distance
perturbative pole masses to two-loops}: $M^{PT2}_b=(4.62 \pm 0.02)$ GeV,
$M^{PT2}_c= (1.41\pm 0.03)$ GeV, which we compare with the updated values of
the {\it non-relativistic pole masses} re-extracted {\it directly} from the
two-loop non-relativistic sum rules: $M^{NR}_b= (4.69~^{-0.01}_{+0.02} \pm
0.02)$ GeV and $M^{NR}_c=(1.44\pm 0.02\pm 0.03)$ GeV. It is also informative to
compare the {\it three-loop} values of the short-distance pole masses:
$M^{PT3}_b=(4.87\pm 0.05 \pm 0.02)$ GeV and $M^{PT3}_c= (1.62\pm 0.07 \pm
0.03)$ GeV, with the {\it dressed mass} $M^{nr}_b = (4.94 \pm 0.10 \pm 0.03)$
GeV, entering into the {\it non-relativistic Balmer formula} including higher
order $\alf$ corrections. The $small$ mass-differences $M^{NR}_b-M^{PT2}_b
\simeq M^{nr}_b-M^{PT3}_b \simeq 70$ MeV and $M_c^{NR}-M_c^{PT2} \simeq (30 \pm
20)$ MeV {\it can measure the size} of the non-perturbative effect induced by
{\it renormalon} type-singularities. An analogous analysis is pursued for the
heavy-light mesons, where a simultaneous {\it re-fit} of the $B$ and $B^*$
masses from relativistic sum rules leads to: $M_b^{PT2}= (4.63 \pm 0.08)$ GeV,


title: Small $x$ Contributions to the Structure Function $F_L(x,Q^2)$

abstract:
  The gluon contributions to $F_L(x,Q^2)$ in ${\cal O}(\alpha_s)$ are
calculated taking into account the transverse momentum of the initial state
parton. In comparison with collinear factorization $F_L(x,Q^2)$, is not
affected at large $x$ but takes smaller values in the small $x$ range. The
onset of the $k_{\perp}$ effect is a function of $Q^2$.


title: Nucleon-Antinucleon Annihilation at the Open Charm Threshold

abstract:
  We discuss the $p\bar{p}$ annihilation into a pair of charmed $D$ mesons not
far from the threshold of the reaction. An interesting interference pattern in
the differential cross section is predicted to arise from the existence of both
$t$-channel charmed-baryon exchange and $s$-channel $\Psi^{''}$ charmonium
resonance amplitudes. We argue that the experimental study of this process
would provide new and valuable information about the unknown
$p\bar{p}\Psi^{''}$ and $\Lambda_c N D$ couplings. These are important to know
to solve the long-standing puzzle of the heavy flavour contents of baryons and
to test the semi-local duality.


title: Light Gluinos

abstract:
  Gluino and lightest neutralino masses are naturally less than a few GeV if
dimension-3 susy-breaking operators are absent from the low energy theory. In
this case gaugino masses come from loops and are calculable in terms of known
particle masses and two mass parameters, $\mu$ and $\tilde{m}$. The
phenomenology of such a scenario is discussed.


title: More on ambiguities in the pole mass

abstract:
  The relation between the pole quark mass and the $\overline{MS}$-renormalized
mass is governed by an infrared renormalon singularity, which leads to an
ambiguity of order $\Lambda_{QCD}$ in the definition of the pole mass. We use
the renormalization group and heavy quark effective theory to determine the
exact nature of this singularity up to an overall normalization. In the abelian
gauge theory, the normalization is computed partially to next-to-leading order
in the flavour expansion.


title:
A Gauge Field Model On $SU(2)_L\times SU(2)_R\times U(1)_Y \times
  \pi_4(G_{YM})$

abstract:
  We construct a gauge field model based on $SU(2)_L\times SU(2)_R\times U(1)_Y
\times \pi_4(SU(2)_L\times SU(2)_R\times U(1)_Y) $ from the principle that both
the original gauge group $G_{YM}$ and the discrete group $\pi_4(G_{YM})$ should
be taken as gauge groups in the sense of non-commutative geometry. We show that
the Yukawa coupling and the Higgs mechanism appear as natural results.


title:
Effects of new physics in the rare decays $B \to K \ell^+ \ell^-$ and $B
  \to K^\ast \ell^+ \ell^-$

abstract:
  We parametrize phenomenologically possible new physics effects and calculate
their influence on the invariant dilepton mass spectrum and the Dalitz plot for
the decays $B \to K \ell^+ \ell^-$ and $B \to K^\ast \ell^+ \ell^-$. Especially
the decay into $K^*$ yields a wealth of new information on the form of the new
interactions since the Dalitz plot is sensitive to subtle interference effects.
We also show how transversely polarized $K^*$-mesons give additional
information.


title:
Projet: Jet Cross Sections in Deeply Inelastic Electron Proton
  Scattering (VERSION 4.1)

abstract:
  PROJET is a parton level Monte Carlo program for the calculation of jet cross
sections in deeply inelastic electron proton scattering. In its present version
it contains the Born level diagrams for the production of (1+1), (2+1) and
(3+1) jets and the next-to-leading order corrections for the production cross
sections of (1+1) and (2+1) jets for all polarisations of the exchanged virtual
photon. In particular, the full angular correlations between the lepton and jet
momenta are implemented. The program permits the application of acceptance cuts
on all external momenta. For this purpose, the program creates an event record
accessible to the user program with all momenta in the laboratory frame and in
the center of momentum frame of the proton and the virtual photon. This option
is indispensable for phenomenological studies because of the strong dependence
of cross sections on phase space restrictions and the large uncertainty of
fragmentation corrections in the proton direction. Since PROJET uses the Monte
Carlo integration method for the evaluation of phase space integrals, the
weights of the generated events can be used to produce distributions of
observables related to jet momenta.


title: Dynamical Supersymmetry Breaking Simplified

abstract:
  We present a model in which supersymmetry is dynamically broken at
comparatively low energies. Previous efforts to construct simple models of this
sort have been hampered by the presence of axions. The present model, which
exploits an observation of Bagger, Poppitz and Randall to avoid this problem,
is far simpler than previous constructions. Models of this kind do not suffer
from the naturalness difficulties of conventional supergravity models, and make
quite definite predictions for physics over a range of scales from $100$'s of
GeV to $1000$'s of TeV. Thus ``Renormalizable Visible Sector Models'' are a
viable alternative to more conventional approaches. Our approach also yields a
viable example of hidden sector dynamical supersymmetry breaking.


title:
Radiative Corrections to Nonleptonic Inclusive B Decays and the
  Semileptonic Branching Ratio of B Mesons

abstract:
  We calculate the radiative corrections to the nonleptonic inclusive B decay
mode $b\to c ud$ taking into account the charm quark mass. The corrections
increase the decay rate by (4--8)\%, depending on the renormalization point.
Using these results, we obtain an improved theoretical prediction for the
semileptonic branching ratio of B mesons. This talk relies on work done in
collaboration with E. Bagan, V.M.\ Braun and P. Gosdzinsky.


title: Where are the beryllium neutrinos?

abstract:
  We show that present experiments imply that neutrinos are nonstandard at the
87\% C.L., independently of solar or nuclear physics. Moreover, if neutrinos
are standard, the $^7$Be flux must be almost zero. Even if we arbitrarily
disregard one of the experiments, the neutrino flux must still be less than
half of the value predicted by standard solar models.


title: Biased Discrete Symmetry Breaking and Fermi Balls

abstract:
  The spontaneous breaking of an approximate discrete symmetry is considered,
with the resulting protodomains of true and false vacuum being separated by
domain walls. Given a strong, symmetric Yukawa coupling of the real scalar
field to a generic fermion, the domain walls accumulate a gas of fermions,
which modify the domain wall dynamics. The splitting of the degeneracy of the
ground states results in the false vacuum protodomain structures eventually
being fragmented into tiny false vacuum bags with a Fermi gas shell (Fermi
balls), that may be cosmologically stable due to the Fermi gas pressure and
wall curvature forces, acting on the domain walls. As fermions inhabiting the
domain walls do not undergo number density freeze out, stable Fermi balls exist
only if a fermion anti-fermion asymmetry occurs. Fermi balls formed with a new
Dirac fermion that possesses no standard model gauge charges provide a novel
cold dark matter candidate.


title: Spin Effects in High Energy Photon-Hadron Scattering in QCD

abstract:
  The spin effects at high energies and momenta transferred $|t|>1 GeV^2$ are
analysed for quark-photon scattering. The energy independence of the ratio of
spin-flip and spin-non-flip amplitudes in the same $\alpha_s$ order of QCD is
obtained. It is shown that the contribution of the spin-dependent quark-pomeron
vertex to the spin-flip amplitude is intensified by off-mass-shell effects in
the quark loop. As a result, the magnitude of this amplitude can reach 20-30\%
from a spin-non-flip one. The dependence of the cross-section on the
form-factor and $\alpha_s^3$ spin-non-flip contributions are observed.


title: Exact Cancellation of Quadratic Divergences in Top Condensation Models

abstract:
  We discuss the hierarchy problem and the corresponding quadratic divergences
in the top mode Standard Model. Quadratic divergences appear at each order
1/N_c since fermionic and bosonic contributions are of different order 1/N_c.
It is shown that the full dynamical system to all orders in 1/N_c admits a
solution, where the sum of all quadratic divergent contributions disappears.


title: Reanalysis of the decay K_L -> pi0 e+ e-

abstract:
  The decay K_L -> pi0 e+ e- is being searched for as a signal of direct Delta
S = 1 CP violation. We provide a thorough updating of the analysis of the three
components of the decay: 1) Direct CP violation, 2) CP violation through the
mass matrix and 3) CP-conserving (two-photon) contributions. First the chiral
calculation of the K_S -> pi0 e+ e- rate, due to Ecker, Pich and de Rafael
(EPR), is updated to include recent results on the nonleptonic amplitude. Then
we systematically explore the uncertainties in this method. These appear to be
so large that they will obscure the direct CP violation unless it is possible
to measure the K_S -> pi0 e+ e- rate. The CP-conserving amplitude remains
somewhat uncertain, but present indications are such that there may be a
sizable CP-violating asymmetry in the e+, e- energies from the interference of
the CP-conserving and CP-violating amplitudes and this may potentially be
useful in determining whether direct CP violation is present.


title: Signals of Neutralino Dark Matter from Earth and Sun

abstract:
  We evaluate the fluxes of up--going muons detectable in a neutrino telescope
and due to the annihilation of relic neutralinos in the Earth and in the Sun,
taking realistically into account the fact that neutralinos might provide only
a fraction of the local (solar neighbourhood) dark matter (DM). We determine
the relation between the exposure $A t$ of the neutrino telescope ($A$ being
the telescope area, $t$ the live time) and the explorable range of the
neutralino mass and composition, when the signal--to--background ratio is
optimized by an appropriate angular selection.


title: Amount of Antiprotons in Cosmic Rays due to Halo Neutralino Annihilation

abstract:
  We evaluate the antiproton--to--proton flux ratio which can be generated by
neutralino--neutralino annihilation in the galactic halo, considering the most
general compositions for the relic neutralinos and modelling the neutralino
local density according to its relic abundance. We find that in the case of
mixed neutralino compositions this $\bar p/p$ ratio is higher than for pure
higgsinos or gauginos. It is shown how the expected improvements in sensitivity
for the new measurements of the $\bar p/p$ may provide very useful information,
complementary to the one obtainable with other experimental means.


title: Principal-Value Resummation for Dilepton Production

abstract:
  We present a new method of resummation of QCD threshold distributions to the
hard scattering function of the dilepton production cross section in
hadron-hadron collisions. Our formulation by-passes the infrared singularities
of the QCD running coupling through a principal value prescription, and does
not require an explicit infrared cut-off. The resulting large corrections
exponentiate, and we discuss asymptotic properties of the exponent. We present
a closed analytical formula for the resummed hard part in momentum space, and
give predictions, at fixed-target energies, for the resulting cross section
which is a bounded function of its kinematic variables in the entire partonic
phase space.


title: Multiloop Calculations in QED by Superparticle Path Integrals

abstract:
  We use the worldline path integral approach to the Bern-Kosower formalism for
extending this formalism to the calculation of higher order corrections to N -
photon scattering. The case of the two-loop QED beta-function is considered in
detail. (Talk given by C. S. at the Workshop QCD 94, Montpellier, France, 7 -
13 July, 1994)


title: Estimates of the higher-order QCD corrections: Theory and Applications

abstract:
  We consider the further development of the formalism of the estimates of
higher-order perturbative corrections in the Euclidean region, which is based
on the application of the scheme-invariant methods, namely the principle of
minimal sensitivity and the effective charges approach. We present the
estimates of the order $O(\alpha^{4}_{s})$ QCD corrections to the Euclidean
quantities: the $e^+e^-$-annihilation $D$-function and the deep inelastic
scattering sum rules, namely the non-polarized and polarized Bjorken sum rules
and to the Gross--Llewellyn Smith sum rule. The results for the $D$-function
are further applied to estimate the $O(\alpha_s^4)$ QCD corrections to the
Minkowskian quantities $R(s) = \sigma_{tot} (e^{+}e^{-} \to {\rm hadrons}) /
\sigma (e^{+}e^{-} \to \mu^{+} \mu^{-})$ and $R_{\tau} = \Gamma (\tau \to
\nu_{\tau} + {\rm hadrons}) / \Gamma (\tau \to \nu_{\tau} \overline{\nu}_{e}
e)$. The problem of the fixation of the uncertainties due to the
$O(\alpha_s^5)$ corrections to the considered quantities is also discussed.


title: The Electromagnetic Pion Form Factor and Instantons

abstract:
  We calculate the electromagnetic pion form factor at intermediate space-like
momentum transfer from the QCD sum rule for the correlation function of two
{\it pseudoscalar } interpolating fields and the electromagnetic current. This
correlator receives essential contributions from direct ({\it i.e.}
small-scale) instantons, which we evaluate under the assumption of an instanton
size distribution consistent with instanton liquid and lattice simulations. The
resulting form factor is in good agreement both with the sum rule based on the
axial-current correlator and with experiment.


title: Status of the Solar Neutrino Puzzle

abstract:
  Using the latest results from the solar neutrino experiments and a few
standard assumptions, I show that the popular solar models are ruled out at the
3$\sigma$ level or at least TWO of the experiments are incorrect.
Alternatively, one of the assumptions could be in error. These assumptions are
spelled out in detail as well as how each one affects the argument.


title:
Next-to-leading order short distance QCD corrections to the effective
  $\Delta S = 2$ Hamiltonian, implications for the $K_L$-$K_S$ mass difference

abstract:
  We report on the results of a calculation of next-to leading order short
distance QCD corrections to the coefficient $\eta_1$ of the effective $\Delta S
= 2$ Lagrangian in the standard model and discuss the uncertainties inherent in
such a calculation. As a phenomenological application we comment on the
contributions of short distance physics to the ${\rm K}_{\rm L}$--${\rm K}_{\rm
S}$ mass difference. This report is based on research work done in
collaboration with Ulrich Nierste.


title:
Dynamic Gluon Confinement in High Energy Processes within Effective QCD
  Field Theory

abstract:
  An effective Lagrangian approach to describe the dynamics of confinement and
symmetry breaking in the process of quark-gluon to hadron conversion is
proposed. The deconfined quark and gluon degrees of freedom of the perturbative
QCD vacuum are coupled to color neutral condensate fields representing the
non-perturbative vacuum with broken scale and chiral symmetry. As a first
application the evolution of gluons emitted by a fragmenting high energy $q\bar
q$ pair from the perturbative to the non-perturbative regime with confinement
is studied. For reasonable parameter choice the solution of the equations of
motion leads to flux tube configurations with a string tension $t \simeq 1$
GeV/fm.


title: Structure Functions and Distributions in Semileptonic Tau Decays

abstract:
  Semileptonic decays of polarized $\tau$ leptons are investigated. The most
general angular distribution of three meson final states ($\tau\rightarrow
\pi\pi\nu,\,K\pi\nu,\, \pi\pi\pi\nu,\\ \,K\pi\pi\nu,\, KK\pi\nu,\, KKK\nu,\,
\eta\pi\pi\nu,\,\ldots{}$) is discussed. It is shown, that the most general
distribution can be characterized by 16 structure functions, most of which can
be determined in currently ongoing high statistics experiments. Emphasis is put
on $\tau$ decays in $e^{+}e^{-}$ experiments where the neutrino escapes
detection and the $\tau$ rest frame cannot be reconstructed. The structure of
the hadronic matrix elements, based on CVC and chiral lagrangians, is
discussed.


title: The determination of $|V_{cb}|$ from semileptonic inclusive decay rates

abstract:
  We report on the determination of $|V_{cb}|$ from the comparison of the
semileptonic inclusive decay rates of B-- and D--mesons using the heavy quark
symmetry of QCD. While the renormalization scale ambiguity does not allow for a
reliable estimate of the quark masses, it almost cancels in the prediction for
$|V_{cb}|$, which reads $|V_{cb}|(\tau_B/1.49\,{\rm ps})^{1/2} = 0.036\pm
0.005$, where the error stems from the uncertainty in the kinetic energy of the
heavy quark inside the meson, in the experimental branching ratios, in QCD
input parameters, and from scale uncertainties. This talk is based on research
work done in collaboration with Patricia Ball.


title:
Polarization Effects in Drell-Yan Type Processes h_1+h_2 ->
  (W,Z,\gamma*,J/psi)+X

abstract:
  The measurement of the angular distribution of leptons from the decay of a
$W$, $Z$, $\gamma^{\ast}$, or $\Jpsi$ produced at high transverse momentum in
hadronic collisions provides a detailed test of the production and decay
mechanism of the spin one state. In the absence of cuts on the final state
leptons, the lepton angular distribution in the lepton pair rest frame is
determined by the polarization of the spin one state. At leading order in
perturbative QCD the general structure of the decay lepton distribution arising
from a $W,Z [\gamma^{\ast},\Jpsi]$ is controlled by six [four] invariant
structure functions. In the presence of cuts, the lepton angular distributions
are dominated by kinematic effects rather than polarization effects. We present
Monte Carlo studies for Tevatron energies and discuss how polarization effects
can be highlighted in the presence of cuts.


title: Skyrmions from a Born-Infeld Action

abstract:
  We consider a geometrically motivated Skyrme model based on a general
covariant kinetic term proposed originally by Born and Infeld. We introduce
this new term by generalizing the Born-Infeld action to a non-abelian $SU(2)$
gauge theory and by using the hidden gauge symmetry formalism. The static
properties of the Skyrmion are then analyzed and compared with other
Skyrme-like models.


title: Isospin Structure of Penguins And Their Consequences in $B$ Physics

abstract:
  Isospin structure of gluon mediated or strong penguin is significantly
altered when the full electroweak corrections are included. This has the
consequence that some previous analyses which relied on a simple isospin
structure in charmless $B$ decays become inapplicable. We present the general
Hamiltonian in next-to-leading order QCD, and illustrate our conclusion
quantitatively for $B\rightarrow \pi\pi$ and $B\rightarrow K\pi$ decays in the
factorization approximation. Some remarks on CP asymmetries in $B$ decays are
also made.


title:
QCD Potential Model for Light-heavy Quarkonia and the Heavy Quark
  Effective Theory

abstract:
  We have investigated the spectra of light-heavy quarkonia with the use of a
quantum-chromodynamic potential model which is similar to that used earlier for
the heavy quarkonia. An essential feature of our treatment is the inclusion of
the one-loop radiative corrections to the quark-antiquark potential, which
contribute significantly to the spin-splittings among the quarkonium energy
levels. Unlike $c\bar{c}$ and $b\bar{b}$, the potential for a light-heavy
system has a complicated dependence on the light and heavy quark masses $m$ and
$M$, and it contains a spin-orbit mixing term. We have obtained excellent
results for the observed energy levels of $D^0$, $D_s$, $B^0$, and $B_s$, and
we are able to provide predicted results for many unobserved energy levels. We
have also used our investigation to test the accuracy of the heavy quark
effective theory. We find that the heavy quark expansion yields generally good
results for the $B^0$ and $B_s$ energy levels provided that $M^{-1}$ and
$M^{-1}\ln M$ corrections are taken into account in the quark-antiquark
interactions. It does not, however, provide equally good results for the energy
levels of $D^0$ and $D_s$, which shows that the effective theory can be applied
more accurately to the $b$ quark than the $c$ quark.


title: Signals For Supersymmetric Unification

abstract:
  Using the Yukawa couplings of the minimal supersymmetric SU(5) model, the
rates for $\mu \to e\gamma$, $\mu \to e$ conversion and $\tau \to \mu \gamma$
are computed. For a selectron mass of 100 GeV, and without exploring the full
parameter space, we find rates which are one order of magnitude beneath present
experimental bounds. It is argued that these relatively large rates have a wide
applicability, so that lepton flavor violating signals provide a more general
test of supersymmetric unification than can be obtained from either proton
decay or neutrino masses.


title: Double charmed baryon production at B-factory

abstract:
  The cross-section for the double charmed baryon production at a $B$-factory
is estimated on the basis of the perturbative QCD calculations for the $c
c$-diquark production as well as of the quark-hadron duality.


title: Quark-Lepton Unification and Rare Meson Decays

abstract:
  We study meson decays mediated by the heavy gauge bosons of the Pati-Salam
model of quark-lepton unification. We consider the scenarios in which the tau
lepton is associated with the third, second, and first generation of quarks.
The most sensitive probes, depending on the scenario, are rare K, pi, and B
decays.


title: Kinetics of Bose-Condensation

abstract:
  The process of condensation in the system of scalar Bosons with weak $\lambda
\phi^4$ interaction is considered. Boltzmann kinetic equation is solved
numerically. Bose condensation proceeds in two stages: At the first stage
condensate is still absent but there is non-zero inflow of particles towards
$\vec{{\bf p}} = 0$ and the distribution function at $\vec{{\bf p}} = 0$ grows
from finite values to infinity. At the second stage there are two components,
condensate and particles, reaching their equilibrium values. We show that the
evolution in both stages proceeds in a self - similar way and find the time
needed for condensation, which is finite.


title: New Metastable Charmonium and the $\psi '$ Anomaly at CDF

abstract:
  Production of metastable charmonium states more massive than the $\psi(3685)$
is expected in models and could be the source of up to $50\%$ of the $\psi$
observed at large $p_T$ at the Tevatron.Narrow $2^{-+},2^{--} c\bar{c}$ are
predicted at around 3.8GeV and radially excited $2^3P_{1,2}$ may also have
suppressed hadronic widths making these states potentially extra sources of
$\psi(3685)$. Colour octet components are believed to dominate $\psi$
production at the Tevatron which suggests that hybrid charmonium production may
also be prominent. Estimates of hybrid production rates and branching ratios
into charmonium suggest that metastable hybrids with mass $\approx$ 4GeV may
play an important role in generating the observed $\psi(3685),\psi(3095)$


title: From unpolarized to polarized quark distributions in the nucleon

abstract:
  Starting from Martin, Roberts and Stirling fit for unpolarized deep inelastic
structure functions and using the newest experimental data on spin asymmetries
we get a fit which provides polarized quark distributions. We analyze the
behaviour of such functions near $x$ equal to 1. The first moments of these
distributions are also discussed. Our fit prefers combination of proton and
neutron data versus proton-deuteron one.


title: Gluon Radiation Patterns in Pomeron Exchange Events

abstract:
  Color singlet two gluon exchange provides a perturbative model for the
pomeron. This mechanism is thought to explain the production of rapidity gaps
in hard dijet events at the Tevatron. It is shown that in $qQ$ scattering via
two gluon color singlet exchange the emission of soft gluons follows closely
the pattern found for $t$-channel photon exchange. Gluon emission is strongly
suppressed between the two quark jets. After hadronization this leads to a
depressed level of hadronic activity between the jets and thus allows the
formation of rapidity gaps.


title: CP violation in the two-Higgs-doublet model: an example

abstract:
  In a general two-scalar-doublet model without fermions, there is a unique
source of CP violation, $ J_1 $, in the gauge interactions of the scalars. It
arises in the mixing of the three neutral physical scalars $ X_1 $, $ X_2 $ and
$ X_3 $. CP violation may be observed via different decay rates for $ X_1
\rightarrow H^+ W^- $ and $ X_1 \rightarrow H^- W^+ $ (or, alternatively, for $
H^+ \rightarrow X_1 W^+ $ and $ H^- \rightarrow X_1 W^- $ --- depending on
which decays are kinematically allowed). I compute the part of those
CP-violating decay-rate differences which is proportional to $ J_1 $. The
CP-invariant final-state-interaction phase is provided by the absorptive parts
of the one-loop diagrams. I check the gauge invariance of the whole
calculation.


title: Heavy Mesons in a Random Instanton Gas

abstract:
  We analyze the correlation function of a meson with one heavy and one light
quark in inverse powers of the heavy quark mass $m_Q$ using a succession of
Foldy-Wouthuysen-type transformations prior to radiative corrections. We
evaluate the correlator to order $m_Q^0$ in a random and dilute gas of
instantons, using the planar approximation. We show, in leading order in the
density, that the heavy quark mass is shifted to the order $m_Q^0$ and that the
induced interaction between the heavy and light quarks is attractive. We also
find it to be an order of magnitude smaller than the 't Hooft interaction
between two light quarks. The shift in the heavy quark mass is related to the
perimeter law of large Wilson loops. The relevance of these results for general
hadronic correlators with heavy quarks is discussed.


title: Leptoproduction of Heavy Quarks in the Fixed and Variable Flavor Schemes

abstract:
  We compare the results of the fixed-flavor scheme calculation of Laenen,
Riemersma, Smith and van Neerven with the variable-flavor scheme calculation of
Aivazis, Collins, Olness and Tung for the case of neutral-current
(photon-mediated) heavy-flavor (charm and bottom) production. Specifically, we
examine the features of both calculations throughout phase space and compare
the structure function $F_2(x,Q^2)$. We also analyze the dependence of $F_2$ on
the mass factorization scale $\mu$. We find that the former is most applicable
near threshold, while the latter works well for asymptotic $Q^2$. The validity
of each calculation in the intermediate region is dependent upon the $x$ and
$Q^2$ values chosen.


title: Formation Time Scales for Quarkonia in a Deconfining Medium

abstract:
  Production of heavy quark antiquark systems in high energy heavy ion
collisions must involve relativistic momentum components in a quantum
mechanical approach. If the color forces are screened in a deconfining medium,
one can define the analog of a formation or separation time by an overlap
integral in the nonrelativistic bound state rest frame. This time parameter has
some interesting properties which depend on the momentum spectrum of the
initial quarks. Consequences of these properties for the phenomenology of
deconfinement signals are discussed.


title:
Leptoproduction of Heavy Quarks in the Fixed and Variable Flavor Schemes
  (CONFERENCE Version)

abstract:
  We compare the results of the fixed-flavor scheme calculation of Laenen,
Riemersma, Smith and van Neerven with the variable-flavor scheme calculation of
Aivazis, Collins, Olness and Tung for neutral-current (photon-mediated)
heavy-flavor (charm and bottom) production. We compare the structure function
$F_2(x,Q^2)$ throughout phase space, and also analyze the $\mu$-dependenceWe
find that the former calculation is most applicable near threshold, while the
latter works well for asymptotic $Q^2$.


title: An Analysis of Non-Oblique Corrections to the $Z b \bar b$ Vertex

abstract:
  We present a model--independent analysis of the $Z b \bar b$ vertex, with the
aim of constraining contributions of new physics to the left- and right--handed
couplings of the $b$. We find that the left--handed coupling of the $b$ is
quite narrowly constrained by present data, but that the right--handed coupling
is still largely unconstrained.


title:
QCD Sum Rule Calculation of Twist-3 Contributions to Polarized Nucleon
  Structure Functions

abstract:
  Using the framework of QCD sum rules we predict the twist-3 contribution to
the second moment of the polarized nucleon structure function $g_2(x)$. As the
relevant local operator depends explicitely on the gluon field, we employ a
recently studied interpolating nucleon current which contains three quark field
and one gluon field operator. Despite the fact that our calculation is based on
the analysis of a completely different correlation function, our estimates are
consitent with those of Balitsky, Braun and Kolesnichenko who used a
three-quark current.


title:
Finite Temperature Effective Potential for Spontaneously Broken $\lambda
  \Phi^4$ Theory

abstract:
  We present a self-consistent calculation of the finite temperature effective
potential for $\lambda \Phi^4$ theory in four dimensions using a composite
operator effective action. We find that in a spontaneously broken theory not
only the so-called daisy and superdaisy graphs contribute to the
next-to-leading order thermal mass, but also resummed non-local diagrams are of
the same order, thus altering the effective potential at small effective mass.


title: Recent Progress in One-Loop Multi-Parton Calculations

abstract:
  We describe techniques that simplify the calculation of one-loop QCD
amplitudes with many external legs, which are needed for next-to-leading-order
(NLO) corrections to multi-jet processes. The constraints imposed by
perturbative unitarity, collinear singularities and a supersymmetry-inspired
organization of helicity amplitudes are particularly useful. Certain sequences
of one-loop helicity amplitudes may be obtained for an arbitrary number of
external gluons using these techniques. We also report on progress in
completing the set of one-loop helicity amplitudes required for NLO three-jet
production at hadron colliders, namely the amplitudes with two external quarks
and three gluons. (Contribution presented by L. Dixon at the workshop
``QCD'94'', Montpellier, France, July 7-13, 1994. To appear in those
proceedings.)


title:
Implications of TeV Flavor Physics for the \Delta I =1/2 Rule and the
  B-meson Semileptonic Branching Ratio

abstract:
  Two of the outstanding discrepancies between weak interaction phenomenology
and the standard model come in the large size of the $\Delta I={1\over 2}$
enhancement in $K$ decays and in the small value of the $B$ semileptonic
branching ratio. We argue that these discrepancies are naturally explained by
chromomagnetic dipole operators arising from new physics at the TeV scale.
These operators are closely connected to diagrams which contribute to the quark
mass matrix, and we show how the proper enhancement of the hadronic decays of
$s$ and $b$ quarks can be linked to generation of particular
Cabbibo-Kobayaski-Maskawa mixing angles or quark masses. We confirm our
model-independent analysis with detailed consideration of supersymmetric models
and of technicolor models with techniscalars. This picture has additional
phenomenological predictions for the $B$ system: The branching ratio of
charmless nonleptonic $B$ decays should be of order 20\%, due to a large rate
for $b\to sg$, while there are no dangerous new contributions to $b\rightarrow
s \gamma$. Sizable contributions to $b \to d \gamma$ are a common feature of
models incorporating this mechanism. In techniscalar models the $Z b \bar b$
coupling is enhanced, in association with sizable contributions to $b \to s
\mu^+ \mu^-$.