title: A new Method for computing One-Loop Integrals

abstract:
  We present a new program package for calculating one-loop Feynman integrals,
based on a new method avoiding Feynman parametrization and the contraction due
to Passarino and Veltman. The package is calculating one-, two- and three-point
functions both algebraically and numerically to all tensor cases. This program
is written as a package for Maple.


title:
Active-sterile neutrino oscillations in the early Universe and the
  atmospheric neutrino anomaly

abstract:
  Cosmology cannot rule out the solution nu_mu <-> nu_s to the atmospheric
neutrino data and thus only Earth experiments will be able to give a definitive
answer. This conclusion holds when a generation of lepton number is taken into
account and one assumes that the sterile neutrino is also slightly mixed with
an eV-tau neutrino. This result cannot be spoiled by a chaotic generation of
lepton domains.


title: Higgs Production: A Comparison of Parton Showers and Resummation

abstract:
  The search for the Higgs boson(s) is one of the major priorities at the
upgraded Fermilab Tevatron and at the CERN Large Hadron Collider (LHC). Monte
Carlo event generators (MCs) are heavily utilized to extract and interpret the
Higgs signal, which depends on the details of the multiple soft-gluon emission
from the initial state partons in hadronic collisions. Thus, it is crucial to
establish the reliability of the MCs used by the experimentalists. In this
paper, the MC based parton shower formalism is compared to that of an analytic
resummation calculation. Theoretical input, predictions and, where they exist,
data for the transverse momentum distribution of Higgs bosons, $Z^0$ bosons,
and photon pairs are compared for the Tevatron and the LHC. This comparison is
useful in understanding the strengths and the weaknesses of the different
theoretical approaches, and in testing their reliability.


title: Reconstructing the Chargino System at $e^+e^-$ Linear Colliders

abstract:
  In most supersymmetric theories charginos, $\tilde{\chi}^\pm_{1,2}$, belong
to the class of the lightest supersymmetric particles. The chargino system can
be reconstructed completely in $e^+e^-$ collider experiments:
$e^+e^-\to\tilde{\chi}_i^+ \tilde{\chi}_j^- [i,j=1,2]$. By measuring the total
cross sections and the asymmetries with polarized beams, the chargino masses
and the gaugino-higgsino mixing angles of these states can be determined
accurately. If only the lightest charginos $\tilde{\chi}_1^\pm$ are
kinematically accessible in a first phase of the machine, transverse beam
polarization or the measurement of chargino polarization in the final state is
needed to determine the mixing angles. From these observables the fundamental
SUSY parameters can be derived: the SU(2) gaugino mass $M_2$, the modulus and
the cosine of the CP-violating phase of the higgsino mass parameter $\mu$, and
$\tan\beta = v_2/v_1$, the ratio of the vacuum expectation values of the two
neutral Higgs doublet fields. The remaining two-fold ambiguity of the phase can
be resolved by measuring the normal polarization of the charginos. Sum rules of
the cross sections can be exploited to investigate the closure of the
two-chargino system.


title: QCD sum rule analysis of excited $\Lambda_c$ mass parameter

abstract:
  The mass parameter of orbitally excited $\Lambda_c$ baryons is calculated by
using QCD sum rule in the framework of heavy quark effective theory. Two kinds
of interpolating current for the excited heavy baryons are introduced. It is
obtained that $\bar{\Lambda}=1.08^{+0.095}_{-0.104}$ GeV for the non-derivative
current and $\bar{\Lambda}=1.06^{+0.090}_{-0.107}$ GeV for the current with
derivative. These results are consistent with experimental data.


title:
Higgs radiation off quarks in supersymmetric theories at e^+e^-
  colliders

abstract:
  Yukawa couplings between Higgs bosons and quarks in supersymmetric theories
can be measured in the processes e^+e^- -> Q Qbar + Higgs. We have determined
the cross sections of these processes in the minimal supersymmetric model
including the complete set of next-to-leading order QCD corrections for all
channels.


title: Measuring Higgs boson couplings at the LHC

abstract:
  For an intermediate mass Higgs boson with SM-like couplings the LHC allows
observation of a variety of decay channels in production by gluon fusion and
weak boson fusion. Cross section ratios provide measurements of various ratios
of Higgs couplings, with accuracies of order 15% for 100 fb^{-1} of data in
each of the two LHC experiments. For Higgs masses above 120 GeV, minimal
assumptions on the Higgs sector allow for an indirect measurement of the total
Higgs boson width with an accuracy of 10 to 20%, and of the H-->WW partial
width with an accuracy of about 10%.


title: Hadronization in the Chromodielectric Model

abstract:
  We study the dynamics of quarks and gluons in the Chromodielectric Model
(CDM), which contains a dynamical description of confinement. Results are
presented for hadronization out of an equilibrated quark--gluon plasma. It is
shown that hadronization is complete and hadrons are classified within the
scheme of CDM.


title: Measuring B -> rho pi decays and the unitarity angle alpha

abstract:
  The decay mode B -> rho pi is currently studied as a channel allowing, in
principle, to measure without ambiguities the angle alpha of the unitarity
triangle. It is also investigated by the CLEO Collaboration where a branching
ratio larger than expected for the decay mode B+/- -> rho0 pi+/- has been
found. We investigate the role that the B* and B(0+) resonances play in these
analyses.


title: SUSY Higgs at the LHC: Effects of light charginos and neutralinos

abstract:
  In view of the latest LEP data we consider the effects of charginos and
neutralinos on the two-photon and bbbar signatures of the Higgs at the LHC.
Assuming the usual GUT inspired relation between M_1 and M_2 we show that there
are only small regions with moderate tanbeta and large stop mixings that may be
dangerous. Pathological models not excluded by LEP which have degeneracy
between the sneutrino and the chargino are however a real danger because of
large branching fraction of the Higgs into invisibles. We have also studied
models where the gaugino masses are not unified at the GUT scale. We take
M_1=M_2/10 as an example where large reductions in the signal at the LHC can
occur. However we argue that such models with a very light neutralino LSP may
give a too large relic density unless the sleptons are light. We then combine
this cosmological constraint with neutralino production with light sfermions to
further reduce the parameter space that precludes observability of the Higgs at
the LHC. We still find regions of parameter space where the drops in the usual
Higgs signals at the LHC can be drastic. Nonetheless, in such scenarios where
Higgs may escape detection we show that one should be able to produce all
charginos and neutralinos. Although the heavier of these could cascade into the
Higgs, the rates are not too high and the Higgs may not always be recovered
this way.


title:
Time-reversal violating rotation of polarization plane of light in gas
  placed in the electric field

abstract:
  The rotation of polarization plane of light in a gas placed in the electric
field is considered. Different mechanisms that cause this phenomenon are
investigated. Angle of polarization plane rotation for transition 6S_{1/2} ->
7S_{1/2} in cesium is estimated. The possibility to observe this effect in
experiment is discussed.


title: Theoretical Summary Lecture for EPS HEP99

abstract:
  This is the proceedings article for the concluding lecture of the 1999 High
Energy Physics Conference of the European Physical Society. In this article, I
review a number of topics that were highlighted at the meeting and have more
general importance in high energy physics. The major topics discussed include:
(1) precision electroweak physics, (2) CP violation, (3) new directions in QCD,
(4) supersymmetry spectroscopy, (5) the experimental physics of extra
dimensions.


title: Higgs Boson Decays to tau-pairs in the s-channel at a Muon Collider

abstract:
  We study the observability of the $\tautau$ decay mode of a Higgs boson
produced in the $s$-channel at a muon collider. We find that the spin
correlations of the $\tautau$ in $\tau\to \pi\nu_{\tau}, \rho\nu_{\tau}$ decays
are discriminative between the Higgs boson signal and the Standard Model
background. Observation of the predicted distinctive distribution can confirm
the spin-0 nature of the Higgs resonance. The relative coupling strength of the
Higgs boson to $b$ and $\tau$ can also be experimentally determined.


title:
Prospects of Measuring General Higgs Couplings at e^+e^- Linear
  Colliders

abstract:
  We examine how accurately the general HZV couplings, with V=Z,gamma, may be
determined by studying e^+e^- --> Hff-bar processes at future e^+e^- linear
colliders. By using the optimal-observable method, which makes use of all
available experimental information, we find out which combinations of the
various HZV coupling terms may be constrained most efficiently with high
luminosity. We also assess the benefits of measuring the tau-lepton helicities,
identifying the bottom-hadron charges, polarizing the electron beam and running
at two different collider energies. The HZZ couplings are generally found to be
well constrained, even without these options, while the HZ-gamma couplings are
not. The constraints on the latter may be significantly improved by beam
polarization.


title: Maximal Neutrino Mixing from a Minimal Flavor Symmetry

abstract:
  We study a number of models, based on a non-Abelian discrete group, that
successfully reproduce the simple and predictive Yukawa textures usually
associated with U(2) theories of flavor. These models allow for solutions to
the solar and atmospheric neutrino problems that do not require altering
successful predictions for the charged fermions or introducing sterile
neutrinos. Although Yukawa matrices are hierarchical in the models we consider,
the mixing between second- and third-generation neutrinos is naturally large.
We first present a quantitative analysis of a minimal model proposed in earlier
work, consisting of a global fit to fermion masses and mixing angles, including
the most important renormalization group effects. We then propose two new
variant models: The first reproduces all important features of the SU(5)xU(2)
unified theory with neither SU(5) nor U(2). The second demonstrates that
discrete subgroups of SU(2) can be used in constructing viable supersymmetric
theories of flavor without scalar universality even though SU(2) by itself
cannot.


title: Radical Conservatism and Nucleon Decay

abstract:
  Unification of couplings, observation of neutrino masses in the expected
range, and several other considerations confirm central implications of
straightforward gauge unification based on SO(10) or a close relative and
incorporating low-energy supersymmetry. The remaining outstanding consequence
of this circle of ideas, yet to be observed, is nucleon instability. Clearly,
we should aspire to be as specific as possible regarding the rate and form of
such instability. I argue that not only esthetics, but also the observed
precision of unification of couplings, favors an economical symmetry-breaking
(Higgs) structure. Assuming this, one can exploit its constraints to build
reasonably economical, overconstrained yet phenomenologically viable models of
quark and lepton masses. Putting it all together, one arrives at reasonably
concrete, hopeful expectations regarding nucleon decay. These expectations are
neither ruled out by existing experiments, nor hopelessly inaccessible.


title:
Higher Twist Contributions To R-Hadron Phenomenology In The Light Gluino
  Scenario

abstract:
  The open light gluino window allows non-trivial higher twist gluino
contributions to the proton wave function. Using a two-component model
originally developed for charm hadroproduction, higher twist intrinsic gluino
contributions to final state R-hadron formation are shown to enhance leading
twist production in the forward $x_{F}$ region. We calculate R-hadron
production at $p_{\rm{lab}}=800$ GeV in pp, pBe, and pCu interactions with
light gluino masses of 1.2, 1.5, 3.5, and 5.0 GeV.


title:
Dyson-Schwinger Equation Approach to the QCD Deconfinement Transition
  and J/Psi Dissociation

abstract:
  We consider an extension of the finite-temperature Dyson-Schwinger equation
(DSE) approach to heavy mesons and quarkonia and apply it to calculate the
cross section for the J/Psi breakup reaction J/Psi + pi --> D + D. We study the
effects of chiral symmetry restoration in the light quark sector on this
process and obtain a critical enhancement of the reaction rate at the chiral/
deconfinement transition. Implications for the kinetics of charmonium
production in ultrarelativistic heavy-ion collisions are discussed with
particular emphasis on the recently observed anomalous J/Psi suppression as a
possible signal for quark matter formation.


title: The Massive Thermal Basketball Diagram

abstract:
  The "basketball diagram" is a three-loop vacuum diagram for a scalar field
theory that cannot be expressed in terms of one-loop diagrams. We calculate
this diagram for a massive scalar field at nonzero temperature, reducing it to
expressions involving three-dimensional integrals that can be easily evaluated
numerically. We use this result to calculate the free energy for a massive
scalar field with a phi^4 interaction to three-loop order.


title:
Some low energy effects of a light stabilized radion in the
  Randall-Sundrum model

abstract:
  In this paper we study some low energy effects of a light stabilized radion
in the Randall-Sundrum scenario. We find that the NLC 500 with its projected
precision level will be able to probe the radion contribution to the anomalous
magnetic moment and electric quadrupole moment of W boson for values of radion
vev up to 500 Gev. On the other hand the BNL experiment E821 will be able to
test the radion contribution to $a_{\mu}$ for 1 Tev radion vev and $m_{\phi}\le
m_{\mu}$. We have also shown that the higgs-radion mixing induces a 2.6%
correction in the WWh coupling. Finally by comparing the radionstrahlung with
the higgsstrahlung process we have found that the LEPI bound on the higgs mass
based on $Z\to hl\bar{l}$ decay mode suggests a lower bound of about 35 Gev on
the radion mass.


title: Do Stops Slow Down Electroweak Bubble Walls?

abstract:
  We compute the wall velocity in the MSSM. We therefore generalize the SM
equations of motion for bubble walls moving through a hot plasma at the
electroweak phase transition and calculate the friction terms which describe
the viscosity of the plasma. We give the general expressions and apply them to
a simple model where stops, tops and W bosons contribute to the friction. In a
wide range of parameters including those which fulfil the requirements of
baryogenesis we find a wall velocity of order v = 0.05-0.1 much below the SM
value.


title: High orders of perturbation theory: are renormalons significant?

abstract:
  According to Lipatov, the high orders of perturbation theory are determined
by saddle-point configurations (instantons) of the corresponding functional
integrals. According to t'Hooft, some individual large diagrams, renormalons,
are also significant and they are not contained in the Lipatov contribution.
The history of the conception of renormalons is presented, and the arguments in
favor of and against their significance are discussed. The analytic properties
of the Borel transforms of functional integrals, Green functions, vertex parts,
and scaling functions are investigated in the case of \phi^4 theory. Their
analyticity in a complex plane with a cut from the first instanton singularity
to infinity (the Le Guillou - Zinn-Justin hypothesis) is proved. It rules out
the existence of the renormalon singularities pointed out by t'Hooft and
demonstrates the nonconstructiveness of the conception of renormalons as a
whole. The results can be interpreted as an indication of the internal
consistency of \phi^4 theory.


title: Constraints on Extra Gauge Bosons in e gamma Collisions

abstract:
  We investigate the sensitivity of e- gamma ---> nu_e nu_mu(bar) mu- to extra
charged gauge bosons. The sensitivity is much below that of e-e+ ---> nu
nu(bar) gamma. We conclude that e- gamma ---> d u(bar) nu_e and e- gamma ---> f
f(bar) e- are also inferior to e+e- collisions in setting bounds on extra
charged and neutral gauge bosons and on four fermion contact interactions.


title:
Probing possible decoherence effects in atmospheric neutrino
  oscillations

abstract:
  It is shown that the results of the Super-Kamiokande atmospheric neutrino
experiment, interpreted in terms of nu_mu<--->nu_tau flavor transitions, can
probe possible decoherence effects induced by new physics (e.g., by quantum
gravity) with high sensitivity, supplementing current laboratory tests based on
kaon oscillations and on neutron interferometry. By varying the (unknown)
energy dependence of such effects, one can either obtain strong limits on their
amplitude, or use them to find an unconventional solution to the atmospheric nu
anomaly based solely on decoherence.


title: Radiative corrections to e+e- --> f+f-

abstract:
  The past ten years of physics with e+e- colliding experiments at LEP and SLAC
have shown the success of these experiments on not only impressively proving
the theoretical predictions of the Standard Model (SM), but also to help
provide stringent bounds on physics beyond the SM. With this experience in
mind, there appear two equally fascinating opportunities for studying
fermion-pair production processes at a future Linear Collider (LC). On the one
hand, performing high precision measurements to the SM, for example, when
running with high luminosity at the Z boson resonance, could be a quick and
feasible enterprise in order to pin down the symmetry breaking mechanism of the
electroweak sector through indirectly determining the masses of a light SM or
MSSM Higgs boson or supersymmetric particles via virtual corrections. On the
other hand, looking for such particles in direct production or other `New
Physics' effects at energies between, for example, roughly 500 and 800 GeV will
naturally be the main motivation to pursue the challenging endeavor of building
and utilizing such a unique facility. These two scenarios for the LC shall be
sketched here, with particular emphasis on the semi-analytical program ZFITTER
for fermion-pair production in comparison with numerical programs like TOPAZ0,
KK2f, and others.


title: Physics at e-e- Colliders

abstract: An overview of the physics motivations for e-e- colliders is presented.


title:
How precisely can we determine the pion-nucleon coupling constant from
  the isovector GMO sum rule?

abstract:
  The isovector GMO sum rule for zero energy forward pion-nucleon scattering is
critically studied to obtain the charged pion-nucleon coupling constant using
the precise negatively charged pion-proton and pion-deuteron scattering lengths
deduced recently from pionic atom experiments. This direct determination leads
to a pseudoscalar charged pion-nucleon coupling constant of 14.23 +- 0.09
(statistic) +- 0.17 (systematic). We obtain also accurate values for the
pion-nucleon scattering lengths.


title: A new determination of the Pomeron intercept in hard processes

abstract:
  A method allowing for a direct comparison of data with theoretical
predictions is proposed for forward jet production at HERA. It avoids the
reconstruction of multi-parton contributions by expressing the experimental
data directly as correction factors on the QCD forward jet cross-section. An
application to the determination of the effective Pomeron intercept in the
BFKL-LO parametrization from dsigma/dx data at HERA leads to a good fit with a
significantly higher effective intercept, alpha_P = 1.43 \pm 0.025(stat.) \pm
>.025(syst.), than for proton (total and diffractive) structure functions. It
is however less than the value of the Pomeron intercept using dijets with large
rapidity intervals obtained at Tevatron. We also evaluate the rapidity veto
contribution to the higher order BFKL corrections. The method can be extended
to other theoretical inputs.


title:
Virtual Sfermion Effects on Vector-Boson Pair Production at e^+e^-
  Colliders

abstract:
  We study the quantum effects on vector-boson pair production in e^+e^-
annihilation induced by the sleptons and squarks of the minimal supersymmetric
extension of the standard model (MSSM) in the one-loop approximation. We list
full analytic results, and quantitatively analyze the resulting deviation from
the standard-model prediction of e^+e^- -> W^+W^- for the supergravity-inspired
MSSM. The latter can be rendered small throughout the whole parameter space by
an appropriate choice of renormalization scheme.


title:
A new approach to the parametrization of the Cabibbo-Kobayashi-Maskawa
  matrix

abstract:
  The CKM-matrix V is written as a linear combination of the unit matrix I and
a matrix U which causes intergenerational-mixing. It is shown that such a V
results from a class of quark-mass matrices. The matrix U has to be hermitian
and unitary and therefore can depend at most on 4 real parameters. The
available data on the CKM-matrix including CP-violation can be reproduced by
$V=(I+iU)/\sqrt{2}$. This is also true for the special case when U depends on
\textit{only 2 real parameters}. There is no CP-violating phase in this
parametrization. Also, for such a V the invariant phase $\Phi \equiv \phi
_{12}+\phi_{23}-\phi_{13}$, satisfies a criterion suggested for `maximal'
CP-violation.


title: Non-Abelian Flat Directions in a Minimal Superstring Standard Model

abstract:
  Recently, by studying exact flat directions of non-Abelian singlet fields, we
demonstrated the existence of free fermionic heterotic-string models in which
the SU(3)_C x SU(2)_L x U(1)_Y-charged matter spectrum, just below the string
scale, consists solely of the MSSM spectrum. In this paper we generalize the
analysis to include VEVs of non-Abelian fields. We find several,
MSSM-producing, exact non-Abelian flat directions, which are the first such
examples in the literature. We examine the possibility that hidden sector
condensates lift the flat directions.


title: Fourth generation effects in rare exclusive B -> K^* l^+ l^- decay

abstract:
  Influence of the fourth generation, if ever exists, on the experimentally
measurable quantities such as invariant dilepton mass distribution, lepton
forward-backward asymmetry, and the ratio (Gamma_L/Gamma_T) of the decay widths
when K* meson is longitudinally and transversally polarized, is studied. Using
the experimental results on the branching ratios for the (B -> X_s) gamma and
semileptonic (B -> X_c l nu) decays, the two possible solutions of the 4x4
Cabibbo-Kobayashi-Maskawa factor (V_{t's} V_{t^'b}) are obtained as a function
of the t'-quark mass. It is observed that the results for the above-mentioned
physical quantities are essentially different from the standard model
predictions only for one solution of the CKM factor. In this case the
above-mentioned physical quantities can serve as efficient tools in search of
the fourth generation. The other solution yields almost identical results with
the SM.


title:
Theorems on the Renormalization Group Evolution of Quark Yukawa
  Couplings and CKM Matrix

abstract:
  We analyze the two loop renormalization group equations in the standard model
and its extensions for the coupling constants and the quark Yukawa couplings.
The key point of our analysis is the observed hierarchy of the quark masses and
the CKM matrix. For the one loop evolution we find the explicit solution for
the evolution of the Yukawa couplings and show the following: 1. the CKM matrix
depends on the energy on only one function of energy; 2. the ratios of the down
quark masses depend on the energy through the same function as the CKM matrix;
3. the diagonalizing matrices of the biunitary transformation of the up quarks
are energy independent. Next we give the explicit form of the two loop
corrections to the evolution of the quark Yukawa couplings and show that the
relative corrections are of the order (\lambda ^{4}) for the quark Yukawa
couplings and of the order (\lambda ^{5}) for the CKM matrix. Finally we give
the equations of the one loop evolution of the squares of the matrix elements
of the CKM matrix and their explicit solution.


title: MSW Effects in Vacuum Oscillations

abstract:
  We point out that for solar neutrino oscillations with the mass-squared
difference of Delta m^2 ~ 10^-10 - 10^-9 eV^2, traditionally known as ``vacuum
oscillation'' range, the solar matter effects are non-negligible, particularly
for the low energy pp neutrinos. One consequence of this is that the values of
the mixing angle theta and pi/2-theta are not equivalent, leading to the need
to consider the entire physical range of the mixing angle 0<=theta<=pi/2 when
determining the allowed values of the neutrino oscillation parameters.


title: The Dark Side of the Solar Neutrino Parameter Space

abstract:
  Results of neutrino oscillation experiments have always been presented on the
(sin^2 2theta, Delta m^2) parameter space for the case of two-flavor
oscillations. We point out, however, that this parameterization misses the half
of the parameter space pi/4 < theta <= pi/2 (``the dark side''), which is
physically inequivalent to the region 0 <= theta <= pi/4 (``the light side'')
in the presence of matter effects. The MSW solutions to the solar neutrino
problem can extend to the dark side, especially if we take the conservative
attitude to allow higher confidence levels, ignore some of the experimental
results in the fits, or relax theoretical predictions. Furthermore even the
so-called ``vacuum oscillation'' solution distinguishes the dark and the light
sides. We urge experimental collaborations to present their results on the
entire parameter space.


title: Disentangling running coupling and conformal effects in QCD

abstract:
  We investigate the relation between a postulated skeleton expansion and the
conformal limit of QCD. We begin by developing some consequences of an
Abelian-like skeleton expansion, which allows one to disentangle
running-coupling effects from the remaining skeleton coefficients. The latter
are by construction renormalon-free, and hence hopefully better behaved. We
consider a simple ansatz for the expansion, where an observable is written as a
sum of integrals over the running-coupling. We show that in this framework one
can set a unique Brodsky-Lepage-Mackenzie (BLM) scale-setting procedure as an
approximation to the running-coupling integrals, where the BLM coefficients
coincide with the skeleton ones. Alternatively, the running-coupling integrals
can be approximated using the effective charge method. We discuss the
limitations in disentangling running coupling effects in the absence of a
diagrammatic construction of the skeleton expansion. Independently of the
assumed skeleton structure we show that BLM coefficients coincide with the
conformal coefficients defined in the small $\beta_0$ (Banks-Zaks) limit where
a perturbative infrared fixed-point is present. This interpretation of the BLM
coefficients should explain their previously observed simplicity and smallness.
Numerical examples are critically discussed.


title: One-loop sfermion corrections to $e^-e^+ \to W^-W^+$ in the MSSM

abstract:
  We study one-loop effects of sfermions on helicity amplitudes for $\eeww$ in
the Minimal Supersymmetric Standard Model. The one-loop contributions are
calculated in the $\bar{\rm MS}$ renormalization scheme. In order to verify the
validity of the analytic calculation and the numerical program, the following
tests are performed. (i) The BRS sum rules hold exactly among the analytic
expressions of the form factors of the $\eeww$ amplitude and those of the
amplitudes where the external $W^\pm$ bosons are replaced by the corresponding
Goldstone bosons $\chi^\pm$, hence they hold within the expected accuracy of
the numerical program. (ii) The one-loop sfermion contribution to the
amplitudes decouple in the heavy mass limit. This property is used to test the
overall normalization of the amplitudes. In order to observe the analytically
exact decoupling, the amplitudes are expanded by the $\bar{\rm MS}$ couplings
of the Standard Model. (iii) The high-energy analytic formulas of the helicity
amplitudes, which are verified by using the equivalence theorem analytically,
are used for the numerical test of the high energy behavior of the amplitudes.
We then investigate the magnitude of the one-loop effects on each helicity
amplitude which may be measured by experiments at future linear colliders.
Under the constraint from available precision data, the one-loop corrections to
a few helicity amplitudes (for example, the longitudinal-$W$-pair production)
can be at most from -0.8% to $+0.6$% in magnitude in the observables. The
corrections in the helicity-summed cross sections are smaller, typically a few
times $\pm 0.1$% at large scattering angles.


title: Fermion Generations from the Higgs Sector

abstract:
  The generation structure in the quark and lepton spectrum is explained as
originating from the excitation spectrum S_n of SU(2)_W doublet scalar fields,
whose ground state S_1 is the Standard Model Higgs field. There is only one
basic family of SU(2)_W doublet left-handed fermions, nu_L, e_L, u_L, d_L,
whose bound states with S_n manifest themselves as the generations of
left-handed quarks and leptons. Likewise, there is only one basic family of the
right-handed fermions, nu_R, e_R, u_R, d_R, which combine with the gauge
invariant scalar fields G_n to produce the right-handed quarks and leptons of
the second and higher generations. There are only four Yukawa coupling
constants, G_nu, G_e, G_u, and G_d, and all quark and lepton masses are
proportional to them. Suppression of flavor changing neutral currents (GIM
mechanism) is automatic. nu_mu and nu_tau are expected to be massive.


title: Emission of light mesons directly from the surface of quark-gluon plasma

abstract:
  On the basis of hydrodynamic model of evolution we consider emission of
lightest (\pi,K,\eta,\rho,\omega,K^*) mesons directly from the surface of
quark-gluon plasma, created in the heavy ion collision, with accounting of
their absorption by surrounding hadronic gas. We evaluate upper and lower
limits on yields of these direct mesons in Pb+Pb collisions at SpS, RHIC and
LHC energies, and find, that even in the case of the lowest yield, direct K,
\eta and heavier mesons dominate over freeze-out ones at soft p_t (p_t < 0.5
GeV/c). This leads to enhancement of the low p_t production of these mesons
which hardly can be explained within pure hadronic gas scenario, and can be
considered as quark-gluon plasma signature.


title:
Can Four-fermion Contact Interactions at One-loop Explain the New Atomic
  Parity Violation Results?

abstract:
  We investigate the possibility that four-fermion contact interactions give
rise to the observed deviation from the Standard Model prediction for the weak
charge of Cesium, through one-loop contributions. We show that the presence of
loops involving the third generation quarks can explain such deviation.


title:
Lepton Flavor Violation: Constraints from exotic muon to electron
  conversion

abstract:
  The exotic neutrinoless $\mu^- - e^-$ nuclear conversion is studied within
the conventional extensions of the standard model as well as in the minimal
supersymmetric (SUSY) models with and without R-parity conservation. The
dependence of the $\mu^- - e^-$ conversion rates on the nucleon and nuclear
structure is consistently taken into account. Using our calculated transition
matrix elements and the available experimental data on the branching ratio
$R_{\mu e^-}$ for $^{48}$Ti and $^{208}$Pb as well as the expected experimental
sensitivity for $^{27}$Al employed as a target in the planned at Brookhaven
$\mu^--e^-$ conversion (MECO) experiment, we extract very severe constraints
for the flavor violation parameters. We especially emphasize on the constraints
resulting for SUSY R-parity violating parameters.


title:
On the Structure of the Virtual Compton Amplitude in the Generalized
  Bjorken Region: Integral Relations

abstract:
  A systematic study is performed of the structure of the twist-2 contributions
to the virtual Compton amplitude in deep-inelastic non-forward scattering for
general spin states in the non-local light cone expansion. The gauge invariance
is proven in this approach for the twist-2 contributions for non-forward
scattering. Relations are derived between the contributing non-forward
amplitudes.


title: Can the Higgs be seen in rapidity gap events at the Tevatron or the LHC?

abstract:
  Double diffractive Higgs production at $pp$ (or $\bar{p}p$) colliders
continues to attract attention as a potential signal in the search for the
boson. We present improved perturbative QCD estimates of the event rates for
both the exclusive and inclusive double diffractive Higgs processes, paying
particular attention to the survival probability of the rapidity gaps. We find
that the major uncertainty is in the prediction for the survival probability
associated with soft rescattering. We show that an analogous process, the
double diffractive production of a pair of jets with large values of $E_T$, has
an event rate which makes it accessible at the Tevatron. Observation of this
process can therefore be used as a luminosity monitor for two- gluon exchange
processes, such as the production of a Higgs boson with rapidity gaps on either
side.


title: Neutrino Tests of General and Special Relativity

abstract:
  We review the status of testing the principle of equivalence and Lorentz
invariance from atmospheric and solar neutrino experiments.


title: Nuclear Enhanced Higher-Twist Effects in the Drell-Yan Process

abstract:
  We calculate the Drell-Yan cross section, resolving the full kinematics of
the lepton pair, at high transverse momentum for hadron nucleus collisions. We
use the general framework of Luo, Qiu and Sterman to calculate double
scattering contributions that are of twist-4 and demonstrate their nuclear
enhancement. By comparing single and double scattering at RHIC energies we find
that double scattering gives contributions of comparable size. We also show
that the angular dependence of the Drell-Yan pair discriminates between the
various double scattering contributions.


title: The $B_c$ mass up to order $\alpha_s^4$

abstract:
  We evaluate in perturbative QCD, up to order $\alpha_s^4$, the mass of the
$B_c$. We use the so-called 1S-mass in order to improve the convergence of the
perturbative series. Our result is $E(B_c)_{pert} = 6326^{+29}_{-9}$ MeV.
Non-perturbative effects are discussed. A comparison with potential models
seems to be consistent with non-perturbative contributions of the order $ -
(40\div 100)$ MeV.


title: Fermion production during preheating after hybrid inflation

abstract:
  At the end of inflation, the coherent oscillations of the inflaton field may
resonantly amplify the long wavelength modes of both bosons and fermions
coupled to it. We study the resonant production of both kinds of particles
during preheating in a model of hybrid inflation. The coherent time evolution
of the inflaton and the Higgs fields after inflation induce a very different
production of fermions depending on whether they are coupled to the Higgs or to
the inflaton. For reasonable values of the model parameters, the fermion
production through parametric resonance can be very efficient. We study the
relative growth of the fermion and boson energy densities during preheating in
hybrid models. During the initial stage of preheating, fermion production
dominates the relative energy density, while the exponential growth of bosonic
modes soon takes over.


title:
Heavy quark production as sensitive test for an improved description of
  high energy hadron collisions

abstract:
  QCD dynamics at small quark and gluon momentum fractions or large total
energy, which plays a major role for HERA, the Tevatron, RHIC and LHC physics,
is still poorly understood. For one of the simplest processes, namely
bottom-antibottom production, next-to-leading-order perturbation theory fails.
We show that the combination of two recently developed theoretical concepts,
the k_perp-factorization and the next-to-leading-logarithmic-approximation BFKL
vertex, gives perfect agreement with data. One can therefore hope that these
concepts provide a valuable foundation for the description of other high energy
processes.


title: Higher-Order QCD Corrections in Prompt Photon Production

abstract:
  We exhibit a method for simultaneously treating recoil and threshold
corrections in single-photon inclusive cross sections, working within the
formalism of collinear factorization. This approach conserves both the energy
and transverse momentum of resummed radiation. At moderate p_T, we find the
potential for substantial enhancements from higher-order perturbative and
power-law nonperturbative corrections.


title: HERA Constraint on Warped Quantum Gravity

abstract:
  We study recent data on deep inelastic e^+ p scattering at HERA to constrain
the parameters of a Randall-Sundrum-type scenario of quantum gravity with a
small extra dimension and a non-factorable geometry.


title: Perspectives in High-Energy Physics

abstract:
  I sketch some pressing questions in several active areas of particle physics
and outline the challenges they present for the design and operation of
detectors.


title: Lambda Polarization in Polarized Proton-Proton Collisions at RHIC

abstract:
  We discuss Lambda polarization in semi-inclusive proton-proton collisions,
with one of the protons longitudinally polarized. The hyperfine interaction
responsible for the $\Delta$-$N$ and $\Sigma$-$\Lambda$ mass splittings gives
rise to flavor asymmetric fragmentation functions and to sizable polarized
non-strange fragmentation functions. We predict large positive Lambda
polarization in polarized proton-proton collisions at large rapidities of the
produced Lambda, while other models, based on SU(3) flavor symmetric
fragmentation functions, predict zero or negative Lambda polarization. The
effect of $\Sigma^0$ and $\Sigma^*$ decays is also discussed. Forthcoming
experiments at RHIC will be able to differentiate between these predictions.


title: HELAC: a package to compute electroweak helicity amplitudes

abstract:
  HELAC is a FORTRAN based package that is able to compute efficiently helicity
amplitudes for arbitrary scattering processes within the standard electroweak
theory. The algorithm exploits the virtues of the Dyson-Schwinger equations as
compared to the traditional Feynman graph approach. All electroweak vertices
are included in both the unitary and Feynman gauges, and computations including
all mass effects are available. A version performing multi-precision
computations with arbitrary - user defined - accuracy is also included,
allowing access to any phase space point for arbitrary high energies.


title:
Precision Mass Determination of the Higgs Boson at Photon-Photon
  Colliders

abstract:
  We demonstrate a measurement of the Higgs boson mass by the method of energy
scanning at photon-photon colliders, using the high energy edge of the photon
spectrum. With an integrated luminosity of 50 $\rm{fb^{-1}}$ it is possible to
measure the standard model Higgs mass to within 110 MeV in photon-photon
collisions for m_h=100 GeV. As for the total width of the Higgs boson, the
statistical error $\Delta\Gamma_h/\Gamma_{h \rm{SM}}=0.06$ is expected for
m_h=100 GeV, if both $\Gamma(h\to\gamma\gamma)$ and $\Gamma(h\to b\bar{b})$ are
fixed at the predicted standard model value.


title:
Time invariance violation in photon-atom and photon-molecule
  interactions

abstract:
  A direct experimental proof of very strong T-invariance violation in
interactions of the photons with atoms and molecules exists in the molecular
physics.


title:
How precisely can the difference method determine the pion-nucleon
  coupling constant?

abstract:
  The Coulomb-like backward peak of the neutron-proton scattering differential
cross section is due to one-pion exchange. Extrapolation to the pion pole of
precise data should allow to obtain the value of the charged pion-nucleon
coupling constant. This was classically attempted by the use of a smooth
physical function, the Chew function, built from the cross section. To improve
accuracy of such an extrapolation one has introduced a difference method. It
consists of extrapolating the difference between the Chew function based on
experimental data and that built from a model where the pion-nucleon coupling
is exactly known. Here we cross-check to which precision can work this novel
extrapolation method by applying it to differences between models and between
data and models. With good reference models and for the 162 MeV neutron-proton
Uppsala single energy precise data with a normalisation error of 2.3 %, the
value of the charged pion-nucleon coupling constant is obtained with an
accuracy close to 1.8 %.


title: Sterile Neutrinos in Big Bang Nucleosynthesis

abstract:
  We investigate analytically the evolution of the primordial neutrino
asymmetry caused by active-sterile neutrino oscillations. In particular, we
concentrate on possible chaotic oscillations of the asymmetry. For a certain
range of parameters, we find that the asymmetry indeed oscillates, provided we
neglect the momentum distribution.


title: Finite pion width effects on the rho-meson and di-lepton spectra

abstract:
  Within a field theoretical model where all damping width effects are treated
self-consistently we study the changes of the spectral properties of rho-mesons
due to the finite damping width of the pions in dense hadronic matter at finite
temperature. The corresponding effects in the di-lepton yields are presented.
Some problems concerning the self consistent treatment of vector or gauge
bosons are discussed.


title: Hyperfine effects in charmed baryons

abstract:
  Hadron masses are calculated in quenched lattice QCD with a fermion action of
the D234 type on an anisotropic lattice. Hyperfine splittings for singly
charmed baryons are found to be in agreement with expectations from the quark
model and with a magnitude slightly larger than experimental values. Masses of
doubly charmed baryons are also calculated and compared to a variety of model
calculations. Hyperfine splittings in doubly charmed baryons are found to be
slightly smaller than in singly charmed states.


title:
Flavour-Conserving CP Phases in Supersymmetry and Implications for
  Exclusive B Decays

abstract:
  We study rare exclusive B decays based on the quark-level transition
b->s(d)l^+l^-, where l=e or mu, in the context of supersymmetric theories with
minimal flavour violation. We present analytic expressions for various mixing
matrices in the presence of new CP-violating phases, and examine their impact
on observables involving B and \bar{B} decays. An estimate is obtained for
CP-violating asymmetries in B->K^(*)l^+l^- and B->rho(pi)l^+l^- decays for the
dilepton invariant mass region 1.2 GeV < M_{l^+l^-}< M_{J/psi}. As a typical
result, we find a CP-violating partial width asymmetry of about -6% (-5%) in
the case of B->pi (B->rho) in effective supersymmetry with phases of O(1),
taking into account the measurement of the inclusive b->s gamma branching
fraction. On the other hand, CP asymmetries of less than 1% are predicted in
the case of B->K^(*). We argue that it is not sufficient to have additional CP
phases of O(1) to observe large CP-violating effects in exclusive b->s(d)l^+l^-
decays.


title: Can the Inflaton and the Quintessence scalar be the same field?

abstract:
  The most recent cosmological data point in the direction of a cosmological
constant dominated universe. A suitable candidate for providing the required
acceleration is a rolling scalar field named ``quintessence''. We address the
issue of building a particle physics model for quintessence in the context of
Susy QCD. We then go on to ask if the quintessence scalar can be identified
with the inflaton field and give two examples in which this is indeed the case.


title:
Single-spin Azimuthal Asymmetries in the ``Reduced Twist-3
  Approximation''

abstract:
  We consider the single-spin azimuthal asymmetries recently measured at the
HERMES experiment for charged pions produced in semi-inclusive deep inelastic
scattering of leptons off longitudinally polarized protons. Guided by the
experimental results and assuming a vanishing twist-2 transverse quark spin
distribution in the longitudinally polarized nucleon, denoted as ``reduced
twist-3 approximation'', a self-consistent description of the observed
single-spin asymmetries is obtained. In addition, predictions are given for the
z dependence of the single target-spin asymmetry.


title: Gravity, particle physics and their unification

abstract:
  We explain the need for a theory of quantum gravity and some general ideas
about string theory, including the idea of the derivation of the Hawking
Bekenstein entropy formula for extremal black holes. We then give a general
description of the correspondence between the large N limit of certain gauge
theories and string theory on spacetimes with boundaries.


title: Exact Solutions of the Dirac Equation for Modified Coulombic Potentials

abstract:
  Exact solutions are found to the Dirac equation for a combination of Lorentz
scalar and vector Coulombic potentials with additional non-Coulombic parts. An
appropriate linear combination of Lorentz scalar and vector non-Coulombic
potentials, with the scalar part dominating, can be chosen to give exact
analytic Dirac wave functions. The method works for the ground state or for the
lowest orbital state with l=j-{1/2}, for any j.


title: Relativistic Symmetry Suppresses Quark Spin-Orbit Splitting

abstract:
  Experimental data indicate small spin-orbit splittings in hadrons. For
heavy-light mesons we identify a relativistic symmetry that suppresses these
splittings. We suggest an experimental test in electron-positron annihilation.
Furthermore, we argue that the dynamics necessary for this symmetry are
possible in QCD.


title: Covariant Description of Composite Meson Systems and Chiral Symmetry

abstract:
  Assuming the spin-independence for confining force, we give a covariant quark
representation of general composite meson systems with definite Lorentz
transformation properties. For benefit of this representation we are able to
deduce automatically the transformation rules of composite mesons for general
symmetry operations from those of constituent (exciton) quarks. Applying this
we investigate especially physical implication of chiral symmetry for the meson
systems, and point out a possibility of existence of new meson multiplets.


title:
CP violation effect in long-baseline neutrino oscillation in the
  four-neutrino model

abstract:
  We investigate CP-violation effect in the long-baseline neutrino oscillation
in the four-neutrino model with mass scheme of the two nearly degenerate pairs
separated with the order of 1 eV, by using the data from the solar neutrino
deficit, the atmospheric neutrino anomaly and the LSND experiments along with
the other accelerator and reactor experiments. By use of the most general
parametrization of the mixing matrix with six angles and six phases, we show
that the genuine CP-violation effect could attain as large as 0.3 for $\Delta
P(\nu_\mu\to\nu_\tau) \equiv P(\nu_\mu\to\nu_\tau) -
P(\bar{\nu_\mu}\to\bar{\nu_\tau})$ and that the matter effect is negligibly
small such as at most 0.01 for $\Delta P(\nu_\mu\to\nu_\tau)$ for $\Delta m^2 =
(1-5)\times 10^{-3} {\rm eV}^2$, which is the mass-squared difference relevant
to the long-baseline oscillation.


title: Influence of a medium on pair photoproduction and bremsstrahlung

abstract:
  The creation of electron-positron pair by a photon and the bremsstrahlung of
an electron in a medium are considered in high-energy region, where influence
of the multiple scattering on the processes (the Landau-Pomeranchuk-Migdal
(LPM) effect) becomes essential. The pair photoproduction probability is
calculated with an accuracy up to the "next to leading logarithm". The integral
characteristics: the radiation length and the total probability of pair
photoproduction are analyzed under influence of the LPM effect, and the
asymptotic expansions of these characteristics are derived.


title: Gravitational forces from Bose-Einstein condensation

abstract:
  The basic idea that gravity can be a long-wavelength effect {\it induced} by
the peculiar ground state of an underlying quantum field theory leads to
consider the implications of spontaneous symmetry breaking through an
elementary scalar field. We point out that Bose-Einstein condensation implies
the existence of long-range order and of a gap-less mode of the (singlet)
Higgs-field. This gives rise to a $1/r$ potential and couples with
infinitesimal strength to the inertial mass of known particles. If this is
interpreted as the origin of Newtonian gravity one finds a natural solution of
the hierarchy problem. As in any theory incorporating the Equivalence
Principle, the classical tests in weak gravitational fields are fulfilled as in
general relativity. On the other hand, our picture suggests that Einstein
general relativity may represent the weak field approximation of a theory
generated from flat space with a sequence of conformal transformations. This
explains naturally the absence of a {\it large} cosmological constant from
symmetry breaking. Finally, one also predicts new phenomena that have no
counterpart in Einstein theory such as typical `fifth force' deviations below
the centimeter scale or further modifications at distances $10^{17}$ cm in
connection with the Pioneer anomaly and the mass discrepancy in galactic
systems.


title:
Born-form approximation and full one-loop results for e^+e^- --> W^+W^-
  --> 4 fermions (+\gamma)

abstract:
  We review the results on representing the differential cross section for
W-pair produciton, including W decay and hard-photon bremsstrahlung, in terms
of a Born-form approximation of fairly simple analytic form. The result of the
Born-form approximation are compared with full-one-loop results. The emphasis
is on the energy range of future $e^+e^-$ (or $\mu^+\mu^-$) colliders.


title: The Pomeron as a Finite Sum of Gluon Ladder

abstract:
  A model for the Pomeron at t=0 is suggested. It is based on the idea of a
finite sum of ladder diagrams in QCD. Accordingly, the number of s-channel
gluon rungs and correspondingly the powers of logarithms in the forward
scattering amplitude depends on the phase space (energy) available, i.e. as
energy increases, progressively new prongs with additional gluon rungs in the
s-channel open. Explicit expressions for the total cross section involving two
and three rungs or, alternatively, three and four prongs (with $\ln^2(s)$ and
$\ln^3(s)$ as highest terms) is fitted to the proton-proton and
proton-antiproton total cross section data in the accelerator region.


title:
Z-peak subtracted representation of Bhabha scattering and search for new
  physics effects

abstract:
  We extend to the special case of Bhabha scattering the "Z-peak subtracted"
representation previously applied to e+e- to f f(bar) (f different from e).
This allows us to analyze the process at any energy while imposing in an
automatic way the constraints set by high precision measurements at the Z peak.
The procedure turns out to be particularly convenient for the search of a
certain class of new physics effects at variable energy. A few examples are
considered and the information thus obtained is combined with the corresponding
one that can be derived from the other e+e- annihilation processes, both at
present (LEP2) and at future colliders. This shows that the role of Bhabha
scattering in this respect can be quite relevant.


title: Yukawa hierarchy from extra dimensions and infrared fixed points

abstract:
  We discuss the existence of hierarchy of Yukawa couplings in the models with
extra spatial dimensions. The hierarchical structure is induced by the power
behavior of the cutoff dependence of the evolution equations which yield large
suppressions of couplings at the compactification scale. The values of coupling
constants at this scale can be made stable almost independently of the initial
input parameters by utilizing the infrared fixed point. We find that the Yukawa
couplings converge to the fixed points very quickly because of the enhanced
energy dependence of the suppression factor from extra dimensions as well as in
the case of large gauge couplings at high-energy scale.


title:
Six-quark decays of off-shell WW pairs via parton-level QCD in
  electron-positron annihilations

abstract:
  We study the decays into six quarks of off-shell pairs of W bosons produced
in electron-positron annihilations, through the O(as^2) order in the strong
coupling constant. We give explicit helicity amplitude formulae. We present
numerical results in the context of phenomenological analyses of relevance at
LEP2 and future Linear Colliders: such as MW determinations, New Physics and
Higgs searches.


title: Constraints on a Model with Pure Right-Handed Third Generation Couplings

abstract:
  We examine constraints on a model with pure right-handed third generation
charged couplings. The parameters of the right-handed mixing matrix and the
right-handed coupling strength are constrained from semi-leptonic B decays, the
mass difference of neutral mesons, the CP violating observables epsilon and
epsilon', and the electric dipole moment of the neutron. We find the model to
be tightly constrained by these parameters with several fine tuning conditions
on the phases in the right-handed mixing matrix. There is also a necessarily
non-zero value of the left and right W mixing parameter. CP asymmetry phases in
neutral B decays are discussed.


title:
Comment on ``Closing the neutrinoless double beta decay window into VEP
  and/or VLI''

abstract:
  The constraints from the non-observation of neutrinoless double beta decay on
the violations of Lorentz invariance (VLI) or violations of the equivalence
principle (VEP) have recently been re-examined (hep-ph/9904298) and it was
claimed that the constraints are not valid. In this reply we point out that
this statement is not correct and prove that the arguments given are wrong.


title:
Constraints on Two-Higgs Doublet Models at Large tan{beta} from W and Z
  decays

abstract:
  We study constraints on type-II two Higgs doublet models at large tan{beta}
from LEP/SLD Z-pole data and from lepton universality violation in W decay. We
perform a global fit and find that, in the context of Z decay, the LEP/SLD
experimental values for lepton universality violation, R_b, and A_b all
somewhat disfavor the model. Contributions from the neutral Higgs sector can be
used to constrain the scalar-pseudoscalar Higgs mass splittings. Contributions
from the charged Higgs sector allow us to constrain the charged Higgs mass. For
tan{beta}=100 we obtain the 1 sigma classical (Bayesian) bounds of m_{H+} > 670
GeV (370 GeV) and 1 > m_{h0}/m_{A0} > 0.68 (0.64). The 2 sigma bounds are weak.
Currently, the Tevatron experimental limits on lepton universality violation in
W decay provide no significant constraint on the Higgs sector.


title:
Relic abundance of dark matter particles: new formulation and new result
  of abundance calculation

abstract:
  A new theoretical framework for computation of the relic abundance of cold
dark matter particles such as LSP is presented and some generic features of new
results are discussed. The most important is a generalization of the Boltzmann
equation to include off-shell effects and its thermal average over cosmic
medium. It is shown that at very low temperatures, much below the mass of
annihilating particles, equilibrium abundance is suppressed only by powers of
temperature instead of the exponential Boltzmann factor. This change gives a
larger relic abundance when heavy particles freeze out at these low
temperatures.


title: Golden measurements at a neutrino factory

abstract:
  The precision and discovery potential of a neutrino factory based on muon
storage rings is studied. For three-family neutrino oscillations, we analyse
how to measure or severely constraint the angle $\theta_{13}$, CP violation,
MSW effects and the sign of the atmospheric mass difference $\Delta m^2_{23}$.
We present a simple analytical formula for the oscillation probabilities in
matter, with all neutrino mass differences non-vanishing, which clarifies the
subtleties involved in disentangling the unknown parameters. The appearance of
``wrong-sign muons'' at three reference baselines is considered: 732 km, 3500
km, and 7332 km. We exploit the dependence of the signal on the neutrino
energy, and include as well realistic background estimations and detection
efficiencies. The optimal baseline turns out to be ${\cal O}(3000$ km).
Analyses combining the information from different baselines are also presented.


title: Neutrinoless double beta decay and new physics in the neutrino sector

abstract:
  Neutrinoless double beta decay belongs to the most sensitive tools for the
search of new physics beyond the standard model. The recent half life limit of
the Heidelberg-Moscow experiment implies restrictive bounds on the absolute
mass scale in the neutrino sector. Possible improvements by the GENIUS project
provide a unique possibility to reconstruct the neutrino mass spectrum. Further
constraints on new interactions in the neutrino sector are given in a
model-independent way. Consequences for neutrino anomalies and theories beyond
the standard model such as left-right symmetric models, R-parity violating SUSY
and leptoquarks are discussed. The potential of double beta decay experiments
in the search for WIMP dark matter is reviewed.


title: Nucleon magnetic moments in an extended chiral constituent quark model

abstract:
  We present results for the nucleon magnetic moments in the context of an
extended chiral constituent quark model based on the mechanism of the Goldstone
boson exchange, as suggested by the spontaneous breaking of chiral symmetry in
QCD. The electromagnetic charge-current operator is consistently deduced from
the model Hamiltonian, which includes all force components for the
pseudoscalar, vector and scalar meson exchanges. Thus, the continuity equation
is satisfied for each piece of the interaction, avoiding the introduction of
any further parameter. A good agreement with experimental values is found. The
role of isoscalar two-body operators, not constrained by the continuity
equation, is also investigated.


title: Future prospects for CP violation in hadron machines

abstract:
  The capabilities of future CP violation experiments in hadron machines are
reviewed. Special emphasis is put on the CDF experiment in the run II of the
Tevatron, due to start taking data in 2001, and on LHCb and BTeV, on a longer
time scale.


title: Heavy Flavour Production in Two-Photon Collisions

abstract:
  We review the production of charm and bottom quarks in two-photon collisions
at e+e- colliders. The next-to-leading order QCD predictions for total cross
sections and differential distributions are compared with recent experimental
results.


title: Orbital Angular Momentum Parton Distributions in Light-Front Dynamics

abstract:
  We study the quark angular momentum distribution in the nucleon within a
light-front covariant quark model. Special emphasis is put into the orbital
angular momentum: a quantity which is very sensitive to the relativistic
treatment of the spin in a light-front dynamical approach. Discrepancies with
the predictions of the low-energy traditional quark models where relativistic
spin effects are neglected, are visible also after perturbative evolution to
higher momentum scales. Orbital angular momentum distributions and their
contribution to the spin sum rule are calculated for different phenomenological
mass operators and compared with the results of the MIT bag model.


title: Theory of epsilon'/epsilon

abstract:
  I shortly review the present status of the theoretical estimates of eps'/eps.
I consider a few aspects of the theoretical calculations which may be relevant
in understanding the present experimental results. In particular, I discuss the
role of final state interactions and in general of non-factorizable
contributions for the explanation of the Delta I = 1/2 selection rule in kaon
decays and eps'/eps. Lacking reliable ``first principle'' calculations,
phenomenological approaches may help in understanding correlations among
theoretical effects and the experimental data. The same dynamics which
underlies the CP conserving selection rule drives eps'/eps in the range of the
recent experimental measurements.


title:
Phenomenology of stops, sbottoms, tau-sneutrinos, and staus at an e+e-
  Linear Collider

abstract:
  We discuss production and decays of stops, sbottoms, tau-sneutrinos, and
staus in e+e- annihilation in the energy range \sqrt{s} = 0.5-1 TeV. We present
numerical predictions within the Minimal Supersymmetric Standard Model for
cross sections and decay rates, including one-loop radiative corrections as
well as initial state radiation. We also study the importance of beam
polarization for the determination of the underlying SUSY parameters. Moreover,
we make a comparison of the potential to study squarks and sleptons of the 3rd
generation between Tevatron, LHC, and Linear Collider.


title: Final State Interactions and epsilon'/epsilon: A Critical Look

abstract:
  We critically analyze recent attempts to include final state interaction
(FSI) effects in the calculation of the CP violating ratio epsilon'/epsilon. In
particular the approach of using the Muskhelishvili-Omnes equation for the
decay amplitudes is examined. We find that the values of the dispersive
correction factors are very sensitive to initial conditions which are, at
present, out of control, and demonstrate that the claimed large enhancement of
epsilon'/epsilon through FSI is questionable. We propose, instead, a different
implementation of this approach which may be useful to lattice determinations
of weak amplitudes.


title: Physics Goals of the Next Century @ CERN

abstract:
  After recalling briefly the main physics issues beyond the Standard Model,
the main physics objectives of experiments at CERN in the coming decade(s) are
reviewed. These include the conclusion of the LEP programme during the year
2000, a limited number of fixed-target experiments during the following years,
the CNGS long-baseline neutrino programme and the LHC, both scheduled to start
in 2005. Then possible accelerator projects at CERN after the LHC are reviewed,
in the expectation that an $e^+ e^-$ linear collider in the TeV energy range
will be built elsewhere. The default option for CERN's next major project may
be the CLIC multi-TeV $e^+ e^-$ collider project. Also interesting is the
option of a three-step scenario for muon storage rings, starting with a
neutrino factory, continuing with one or more Higgs factories, and culminating
in a $\mu^+ \mu^-$ collider at the high-energy frontier.


title: New exotics in the double beta decay contributions zoo

abstract:
  We discuss the potential of neutrinoless double beta decay for testing
Lorentz invariance and the weak equivalence principle as well as contributions
from dilaton exchange gravity in the neutrino sector. While neutrino
oscillation bounds constrain the region of large mixing of the weak and
gravitational eigenstates, we obtain new constraints on violations of Lorentz
invariance and the equivalence principle from neutrinoless double beta decay,
applying even in the case of no mixing. Double beta decay thus probes a totally
unconstrained region in the parameter space.


title: SIMP (Strongly Interacting Massive Particle) Search

abstract:
  We consider laboratory experiments that can detect stable, neutral strongly
interacting massive particles (SIMPs). We explore the SIMP annihilation cross
section from its minimum value (restricted by cosmological bounds) to the barn
range, and vary the mass values from a GeV to a TeV.
  We also consider the prospects and problems of detecting such particles at
the Tevatron.


title: Spin effects in the fragmentation of a transversely polarized quark

abstract:
  An azimuthal dependence of pions produced in polarized Deep Inelastic
Scattering, gamma^* - p(transv. polarized) -> pion + X, has been recently
observed and might be related to the so-called Collins effect. We discuss in
details, for a general spin configuration of the nucleon, the kinematics of the
process and methods of extracting information on the fragmentation properties
of a polarized quark. Assuming that the observed azimuthal dependence is indeed
due to Collins effect, we derive a lower bound estimate for the size of the
quark analysing power, which turns out to be large.


title: Penguins and Mixing Dependent CP Violation

abstract:
  Constraints on angles of Unitarity triangle are reviewed, and in particular
constraint on $\gamma$ from limit on $\Delta m_s$ is emphasized. Effects of
penguin diagram on measurement of $\beta$ and $\alpha$ are then reviewed. New
measurements on $B \to \pi^+\pi^-$ in QCD improved factorization approximation
suggest large penguin effects. It is possible to estimate the error in
measurement of $\alpha$ as a function of $\gamma$ for different $|V_{ub}
/V_{cb}|$ values.


title: Qualitative Signals of New Physics in B-Bbar Mixing

abstract:
  It is expected that, within the next three years, the determination of the
CKM matrix elements with the least theoretical uncertainty will arise from the
measurements of CP violation in B_d --> J/\psi K_S decays and from Bs-Bsbar
mixing. If there is significant new physics in Bs-Bsbar mixing, then those
experiments will not yield the correct values for the CKM matrix elements. As a
result, a qualitative signal of new physics may appear in the CP violation of
decays like B_d --> pi+ pi-.


title: Dispersion Laws for Goldstone Bosons in a Color Superconductor

abstract:
  The effective action for Goldstone bosons in the color-flavor locking phase
of dense QCD is analyzed. Interaction terms and higher derivatives in the
effective action appear to be controlled by different scales. At energies of
order of the superconducting gap, the derivative expansion breaks down, while
interactions still remain suppressed. The effective action valid at energies
and momenta comparable to the gap is derived. Dispersion laws following from
this action are such that the energy of Goldstone bosons is always smaller than
the gap in the quasiparticle spectrum, and Goldstone bosons always propagate
without damping.


title: Neutrino decay and long base-line oscillation experiments

abstract:
  Considering neutrinos as time-like leptons one may estimate the three-body
decay probability of muon neutrinos in long base-line accelerator experiments.
In the extreme assumption of time-space symmetry the absolute value of the
transcendent mass of a muon neutrino is equal to the rest mass of its bradyon
partner which is, however, strongly suppressed in measurements using the weak
interaction. This decay, neglecting small oscillations or other effects, leads
to a strong dependence of the effect on the base-line distance. As a result,
few hundred kilometre long baseline experiments might hardly see muon-like
events. Total rates of electron-like events from three-body decay are
calculated for K2K, MINOS and ICARUS. Shorter base-line experiments able to see
clearly the effect of muon neutrino decay are very promissing component of long
base-line projects.


title: Recent progress in Affleck-Dine baryogenesis

abstract:
  In the MSSM, cosmological scalar field condensates formed along flat
directions of the scalar potential (Affleck-Dine condensates) are typically
unstable with respect to formation of Q-balls, a type of non-topological
soliton. I discuss the creation and growth of the quantum seed fluctuations
which catalyse the collapse of the condensate. In D-term inflation models, the
fluctuations of squark fields in the flat directions also give rise to
isocurvature density fluctuations stored in the Affleck-Dine condensate. After
the condensate breaks up, these can be perturbations in the baryon number, or,
in the case where the present neutralino density comes directly from B-ball
decay, perturbations in the number of dark matter neutralinos. The latter case
results in a large enhancement of the isocurvature perturbation, which should
be observable by PLANCK.


title: Non-Baryonic Dark Matter - Observational Evidence and Detection Methods

abstract:
  The evidence for the existence of dark matter in the universe is reviewed. A
general picture emerges, where both baryonic and non-baryonic dark matter is
needed to explain current observations. In particular, a wealth of
observational information points to the existence of a non-baryonic component,
contributing between around 20 and 40 percent of the critical mass density
needed to make the universe geometrically flat on large scales. In addition, an
even larger contribution from vacuum energy (or cosmological constant) is
indicated by recent observations. To the theoretically favoured particle
candidates for non-baryonic dark matter belong axions, supersymmetric
particles, and of less importance, massive neutrinos. The theoretical
foundation and experimental situation for each of these is reviewed. Direct and
indirect methods for detection of supersymmetric dark matter are described in
some detail. Present experiments are just reaching the required sensitivity to
discover or rule out some of these candidates, and major improvements are
planned over the coming years.


title: B_c Decays and Lifetime in QCD Sum Rules

abstract:
  In the framework of three-point QCD sum rules, the form factors for the
semileptonic decays of B_c --> B_s(B_s^*) l \nu are calculated with account for
the Coulomb-like alpha_s/v-corrections in the heavy quarkonium. The generalized
relations due to the spin symmetry of HQET/NRQCD for the form factors are
derived at the recoil momentum close to zero. The nonleptonic decays are
studied using the assumption on the factorization. The B_c meson lifetime is
estimated by summing up the dominating exclusive modes in the c --> s
transition combining the current calculations with the previous analysis of b
--> c decays in the sum rules of QCD and NRQCD.


title:
Looking for Z' bosons in Supersymmetric E_6 Models through Electroweak
  Precision Data

abstract:
  We review constraints on additional Z' bosons predicted in supersymmetric
(SUSY) E_6 models from electroweak experiments - Z-pole experiments, mW
measurements and the low-energy neutral current (LENC) experiments. Four
representative models - \chi,\psi, \eta, \nu models - are studied in some
detail. We find that the improved data of parity violation in cesium atom,
which is 2.2-\sigma away from the Standard Model (SM) prediction, could be
explained by the exchange of the heavy mass eigenstate Z_2 in the intermediate
state. The improvement over the SM can be found in \chi, \eta, \nu models,
where the total \chi^2 of the fit to the 26 data points decreases by about five
units, owing to the better fit to the atomic parity violation. Impacts of the
kinetic mixing between the U(1)_Y and U(1)' gauge bosons on the \chi^2-analysis
are studied. We find that the Z' model with (\beta_E, \delta)=(-\pi/4,0.2),
where \beta_E is the mixing angle between Z_\chi and Z_\psi bosons and \delta
denotes the kinetic mixing, shows the most excellent fit to the data: the total
\chi^2 decreases by about seven units as compared to the SM. We introduce the
effective mixing parameter \zeta, a combination of the mass and the kinetic
mixing parameters. The 95% CL lower mass bound of Z_2 can be shown as a
function of \zeta. A theoretical prediction on \zeta and the U(1)'gauge
coupling g_E is studied for the \chi,\psi,\eta and \nu models by assuming the
minimal particle content of the SUSY E_6 models.


title: Photon mixing in universes with large extra-dimensions

abstract:
  In presence of a magnetic field, photons can mix with any particle having a
two-photon vertex. In theories with large compact extra-dimensions, there
exists a hierachy of massive Kaluza-Klein gravitons that couple to any photon
entering a magnetic field. We study this mixing and show that, in comparison
with the four dimensional situation where the photon couples only to the
massless graviton, the oscillation effect may be enhanced due to the existence
of a large number of Kaluza-Klein modes. We give the conditions for such an
enhancement and then investigate the cosmological and astrophysical
consequences of this phenomenon; we also discuss some laboratory experiments.
Axions also couple to photons in the same way; we discuss the effect of the
existence of bulk axions in universes with large extra-dimensions. The results
can also be applied to neutrino physics with extra-dimensions.


title:
The three-leptons signature from resonant sneutrino production at the
  LHC

abstract:
  The resonant production of sneutrinos at the LHC via the R-parity violating
couplings $\l '_{ijk} L_i Q_j D^c_k$ is studied through its three-leptons
signature. A detailed particle level study of signal and background is
performed using a fast simulation of the ATLAS detector. Through the full
reconstruction of the cascade decay, a model-independent and precise
measurement of the masses of the involved sparticles can be performed. Besides,
this signature can be detected in a large part of the SUSY parameter space and
for wide ranges of values of several $\l '_{ijk}$ coupling constants.


title: Current Status of Radiative B Decays

abstract:
  A current status report on radiative inclusive and exclusive B decays is
presented.


title: Soft-Gluon Resummation and PDF Theory Uncertainties

abstract:
  Parton distribution functions are determined by the comparison of
finite-order calculations with data. We briefly discuss the interplay of higher
order corrections and PDF determinations, and the use of soft-gluon resummation
in global fits.


title: Spin polarisabilities of the nucleon at NLO in the chiral expansion

abstract:
  We present a calculation of the fourth-order (NLO) contribution to
spin-dependent Compton scattering in heavy-baryon chiral perturbation theory,
and we give results for the four spin polarisabilities. No low-energy
constants, except for the anomalous magnetic moments of the nucleon, enter at
this order. For forward scattering the fourth-order piece of the spin
polarisability of the proton turns out to be almost twice the size of the
leading piece, with the opposite sign. This leads to the conclusion that no
prediction can currently be made for this quantity. For backward scattering the
fourth-order contribution is much smaller than the third-order piece which is
dominated by the anomalous scattering, and so cannot explain the discrepancy
between the CPT result and the current best experimental determination.


title: The Higgs sector of the MSSM in the decoupling limit

abstract:
  We study the heavy Higgs sector of the MSSM composed of the H^\pm, H^0 and
A^0 particles in the so-called decoupling limit where m_{A^0} >> m_Z. By
integrating out these heavy Higgs particles to one-loop, we compute the
effective action for the electroweak gauge bosons and find out that, in the
decoupling limit, all the heavy Higgs effects can be absorbed into
redefinitions of the Standard Model electroweak parameters. This demonstrates
explicitely that the decoupling theorem works for the heavy MSSM Higgs
particles. This is also compared with the paradigmatic and different case of
the Standard Model heavy Higgs particle. Finally, this work together with our
two previous works, complete the demonstration that all the non-standard
particles in the MSSM, namely, squarks, sleptons, charginos, neutralinos and
the heavy Higgs particles, decouple to one-loop from the low energy electroweak
gauge boson physics.


title: Seeking Gauge Bileptons in Linear Colliders

abstract:
  A promising direction to find physics beyond the standard model is to look
for violation of $L_{e,\mu,\tau}$ conservation. In particular the process $e^-
e^- \to \mu^- \mu^-$ with the exchange of a gauge bilepton has a striking
signal without background and is predicted in the most economical model to have
a cross-section an order of magnitude higher than previous estimates.


title:
CP,T and/or CPT Violations in the K0-K0bar System --Implications of the
  KTeV,NA48 and CPLEAR Results

abstract:
  Possible violation of CP, T and/or CPT symmetries in the $\ko$-$\kob$ system
is studied from a phenomenological point of view. For this purpose, we first
introduce parameters which represent violation of these symmetries in mixing
parameters and decay amplitudes in a convenient and well-defined way and,
treating these parameters as small, derive formulas which relate them to the
experimentally measured quantities. We then perform numerical analyses, with
the aid of the Bell-Steinberger relation, to derive constraints to these
symmetry-violating parameters, firstly paying particular attention to the
results reported by KTeV Collaboration and NA48 Collaboration, and then with
the results reported by CPLEAR Collaboration as well taken into account. A case
study, in which either CPT symmetry or T symmetry is assumed, is also carried
out. It is demonstrated that CP and T symmetries are violated definitively at
the level of 10^{-4} in $2\pi$ decays and presumably at the level of 10^{-3} in
the $\ko-\kob$ mixing, and that the Bell-Steinberger relation helps us to
establish CP and T violations being definitively present in the $\ko-\kob$
mixing and to test CPT symmetry to a level of 10^{-4} ~ 10^{-5}.


title:
Baryon stopping in high energy collisions and the extrapolation of
  hadron production models to Cosmic Ray energies

abstract:
  A new striking feature of hadron production in nuclear collisions is the
large stopping of the participating nucleons in hadron-nucleus and
nucleus-nucleus collisions. This enhanced baryon stopping can be understood
introducing new diquark breaking mechanisms in multistring models of hadron
production. Here we show, that similar diquark breaking mechanisms occur at
high energy even in hadron-hadron collisions. This effect leads to significant
changes in the extrapolation of these models to Cosmic Ray energies.


title: WGamma and ZGamma production at Hadron Colliders

abstract:
  We present a general purpose Monte Carlo program for the calculation of any
infrared safe observable in WGamma and ZGamma production at hadron colliders at
next-to-leading order in alpha_s. We treat the leptonic decays of the W and
Z-boson in the narrow-width approximation, but retain all spin information via
decay angle correlations. The effect of anomalous triple gauge boson couplings
is investigated and we give the analytical expressions for the corresponding
amplitudes. Furthermore, we propose a way to study the effect of anomalous
couplings without introducing the ambiguity of form factors.


title:
Numerical Solution of the Spinless Salpeter Equation by a Semianalytical
  Matrix Method (a Mathematica 4.0 routine)

abstract:
  In quantum theory, the so-called "spinless Salpeter equation," the
relativistic generalization of the nonrelativistic Schroedinger equation, is
used to describe both bound states of scalar particles and the spin-averaged
spectra of bound states of fermions. A numerical procedure solves the spinless
Salpeter equation by approximating this eigenvalue equation by a matrix
eigenvalue problem with explicitly known matrices.


title: Measurement of entropy of a multiparticle system: a do-list

abstract:
  An algorithm for measurement of entropy in multiparticle systems, based on
recently published proposal of the present authors, is given. Dependence on
discretization of the system and effects of multiparticle correlations are
discussed in some detail.


title: Neutrino oscillation, SUSY GUT and B decay

abstract:
  Effects of supersymmetric particles on flavor changing neutral current and
lepton flavor violating processes are studied in the supersymmetric SU(5) grand
unified theory with right-handed neutrino supermultiplets. Using input
parameters motivated by neutrino oscillation, it is shown that the
time-dependent CP asymmetry of radiative B decay can be as large as 30% when
the $\tau \to \mu \gamma$ branching ratio becomes close to the present
experimental upper bound. We also show that the $B_s$--$\bar{B}_s$ mixing can
be significantly different from the presently allowed range in the standard
model.


title:
Anomalous quartic couplings in six-fermion processes at the Linear
  Collider

abstract:
  The dimension-four genuine anomalous quartic couplings are studied in
processes of six-fermion production via e+e- collisions. Complete tree-level
electroweak calculations are performed including initial-state-radiation and
beamstrahlung. The analysis of final-state distributions can be used to find
kinematical cuts to enhance the effects of anomalous couplings. For the
parameters of the custodial-symmetry-conserving anomalous couplings a
sensitivity in the range between 10^{-3} and 10^{-2} can be expected at 1 TeV.


title: Precision measurements of IVB parameters and bounds on new physics

abstract:
  The main purpose of this thesis is to discuss the impact of electroweak
precision measurements on the present knowledge of particle physics, both in
the framework of the Standard Model and of its most straightforward extensions.
In Chapter 1 we give a general overview of the electroweak sector of the SM and
of SUSY phenomenology. In Chapter 2 we deal with different definitions of the
electroweak mixing angle, with particular attention to the relation between the
phenomenological angle $\theta$ and the MS parameter $\hat\theta$. In Chapter 3
we use results found in the previous chapter to discuss in detail how both the
decoupling and the non-decoupling approach to the running of coupling constants
in the MS scheme produce the same numerical value of $m_{GUT}$, despite of the
different initial conditions. In Chapter 4 we derive simple analytical formulas
for the contribution of a chargino almost degenerate with the lightest
neutralino to electroweak observables, showing that in the case of wino
domination the study of oblique corrections allows a concrete improvement of
experimental bounds on chargino mass. Finally, in Chapter 5 we consider the
possibility of extra fermion generations, proving that they are strongly
disfavoured by the present experimental data if all particles are heavier that
Z-boson, while for the specific case of the extra neutrino around 50 GeV in
mass (still allowed by experimental data) the quality of the fit is not worse
than the SM.


title:
The contribution of $\Sigma^* \to \Lambda\pi$ to measured $\Lambda$
  polarization

abstract:
  Calculations of the polarization of $\Lambda$ and $\bar{\Lambda}$ particles
after fragmentation of a polarized quark produced in processes like $Z$-decay
and deep inelastic polarized lepton scattering must include $\Lambda$ and
$\bar{\Lambda}$ produced as decay products of $\Sigma^0$ and $\Sigma^*$ as well
as those produced directly. These decay contributions are significant and not
feasibly included in theoretical calculations based on QCD without additional
input from other experimental data. Furthermore these contributions depend on
the spin structure of the $\Sigma^0$ or $\Sigma^*$ and are not directly related
to the structure function of the $\Lambda$


title: Some remarks on the interpretation of degree of nonextensivity

abstract:
  Recently we have demostrated that the nonextensitivity parameter q occuring
in some applications of Tsallis statistics (known also as index of the
corresponding L\'evy distribution) is, in the q>1 case, given entirely by the
fluctuations of the parameters of the usual exponential distribution. We show
here that this interpretation is valid also for the q<1 case. The parameter q
is therefore a measure of fluctuations of the parameters of the usual
exponential distribution.


title: Non-accelerator neutrino mass searches

abstract:
  The current status of non-accelerator based searches for effects of a
non-vanishing neutrino mass is reviewed. Beside the direct kinematical methods
this includes searches for magnetic moments and a discussion of the solar
neutrino problem. Double beta decay is not included.


title:
Updated Global Analysis of the Atmospheric Neutrino Data in terms of
  neutrino oscillations

abstract:
  A global analysis of all the available atmospheric neutrino data is presented
in terms of neutrino oscillations in the nu_mu -> nu_tau and nu_mu -> nu_s
channels, where nu_s denotes a sterile neutrino. We perform our analysis of the
contained events data as well as the upward-going neutrino-induced muon fluxes.
In addition to the previous data samples of Frejus, Nusex, IMB and Kamioka
experiments, we include the full data set of the 52 kton-yr of
Super-Kamiokande, the recent 4.6 kton-yr contained events of Soudan2 and the
results on upgoing muons from the MACRO and Baksan detectors. From the
statistical analysis it emerges that the nu_mu -> nu_tau channel provides the
best agreement with the combined data, with a best fit point of sin^2(2 theta)
= 0.99 and Delta m^2 = 3.0 * 10^{-3} eV^2. Although somehow disfavoured, the
nu_mu -> nu_s channels cannot be ruled out on the basis of the global fit to
the full set of observables.


title: Unusual bound states of quark matter within the NJL model

abstract:
  Properties of dense quark matter in and out of chemical equilibrium are
studied within the SU(3) Nambu-Jona-Lasinio model. In addition to the 4-fermion
scalar and vector terms the model includes also the 6-fermion flavour mixing
interaction. First we study a novel form of deconfined matter, meso-matter,
which is composed of equal number of quarks and antiquarks. It can be thought
of as a strongly compressed meson gas where mesons are melted into their
elementary constituents, quarks and antiquarks. Strongly bound states in this
quark-antiquark matter are predicted for all flavour combinations of
quark-antiquark pairs. The maximum binding energy reaches up to 180 MeV per
pair for mixtures with about 70% of strange quark-antiquark pairs. Equilibrated
baryon-rich quark matter with various flavour compositions is also studied. In
this case only shallow bound states appear in systems with a significant
admixture (about 40%) of strange quarks (strangelets). Their binding energies
are quite sensitive to the relative strengths of scalar and vector
interactions. The common property of all these bound states is that they appear
at high particle densities when the chiral symmetry is nearly restored. Thermal
properties of meso-matter as well as chemically equilibrated strange quark
matter are also investigated. Possible decay modes of these bound states are
discussed.


title: Matter Effects on Neutrino Oscillations in Long Baseline Experiments

abstract:
  We calculate matter effects on neutrino oscillations relevant for long
baseline experiments. In particular, we compare the results obtained with
constant density along the neutrino path versus results obtained by
incorporating the actual density profiles in the Earth. We study the dependence
of the oscillation signal on both $E/\Delta m^2_{atm}$ and on the angles in the
leptonic mixing matrix. We also comment on the influence of $\Delta m^2_{sol}$
on the oscillations. The results show quantitatively how, as a function of
these input parameters, matter effects can cause significant (25 %) changes in
the oscillation probabilities. An important conclusion is that matter effects
can be useful in amplifying certain neutrino oscillation signals and helping
one to obtain measurements of mixing parameters and the magnitude and sign of
$\Delta m^2_{atm}$.


title: Anomalous Flavor U(1): Predictive Texture For Bi-maximal Neutrino Mixing

abstract:
  We present a scenario which naturally provides bi-maximal neutrino mixings
for a simultaneous explanation of the recent atmospheric and solar neutrino
data. A crucial role is played by an anomalous flavor ${\cal U}(1)$ symmetry,
which is also important for a natural understanding of charged fermion mass
hierarchies and magnitudes of the CKM matrix elements. Within MSSM the solar
neutrino problem can be resolved either through vacuum oscillations or the
large mixing angle MSW solution. In supersymmetric GUTs such as SU(5) and
SO(10) the MSW solution is realized. If the flavor ${\cal U}(1)$ also mediates
supersymmetry breaking, the vacuum solution in MSSM is eliminated, and only the
large mixing angle MSW solution survives.


title: Inflation and Monopoles in Supersymmetric SU(4)_c x SU(2)_L x SU(2)_R

abstract:
  We show how hybrid inflation can be successfully realized in a supersymmetric
model with gauge group G_{PS}= SU(4)_c x SU(2)_L x SU(2)_R. By including a
non-renormalizable superpotential term, we generate an inflationary valley
along which G_{PS} is broken to the standard model gauge group. Thus,
catastrophic production of the doubly charged magnetic monopoles, which are
predicted by the model, cannot occur at the end of inflation. The results of
the cosmic background explorer can be reproduced with natural values (of order
10^{-3}) of the relevant coupling constant, and symmetry breaking scale of
G_{PS} close to 10^{16} GeV. The spectral index of density perturbations lies
between unity and 0.9. Moreover, the mu-term is generated via a Peccei-Quinn
symmetry and proton is practically stable. Baryogenesis in the universe takes
place via leptogenesis. The low deuterium abundance constraint on the baryon
asymmetry, the gravitino limit on the reheat temperature and the requirement of
almost maximal mu neutrino - tau neutrino mixing from SuperKamiokande can be
simultaneously met with mu-neutrino, tau-neutrino and heaviest Dirac neutrino
masses determined from the large angle MSW resolution of the solar neutrino
problem, the SuperKamiokande results and SU(4)_c symmetry respectively.


title: The minimum width condition for neutrino conversion in matter

abstract:
  We find that for small vacuum mixing angle $\theta$ and low energies ($s\ll
M^2_Z$) the width of matter, $d_{1/2}$, needed to have conversion probability
$P\geq 1/2$ should be larger than $d_{min}= \pi/(2\sqrt{2} G_{F} \tan 2
\theta)$: $d_{1/2}\geq d_{min}$. Here $G_F$ is the Fermi constant, $s$ is the
total energy squared in the center of mass and $M_Z$ is the mass of the $Z$
boson. The absolute minimum $d_{1/2}=d_{min}$ is realized for oscillations in a
uniform medium with resonance density. For all the other density distributions
(monotonically varying density, castle wall profile, etc.) the required width
$d_{1/2}$ is larger than $d_{min}$. The width $d_{min}$ depends on $s$, and for
$Z$-resonance channels at $s\sim M^2_Z$ we get that $d_{min}(s)$ is 20 times
smaller than the low energy value. We apply the minimum width condition, $d\geq
d_{min}$, to high energy neutrinos in matter as well as in neutrino background.
Using this condition, we conclude that the matter effect is negligible for
neutrinos propagating in AGN and GRBs environments. Significant conversion can
be expected for neutrinos crossing dark matter halos of clusters of galaxies
and for neutrinos produced by cosmologically distant sources and propagating in
the universe.


title: Charge cross-over at the U(1)-Higgs phase transition

abstract:
  The type-I region of phase transitions at finite temperature of the
U(1)-Higgs theory in 3+1 dimensions is investigated in detail using a Wilsonian
renormalisation group. We consider in particular the quantitative effects
induced through the cross-over of the scale-dependent Abelian charge from the
Gaussian to a non-trivial Abelian fixed point. As a result, the strength of the
first-order phase transition is weakened. Analytical solutions to approximate
flow equations are obtained, and all characteristics of the phase transition
are discussed and compared to the results obtained from perturbation theory. In
addition, we present a detailed quantitative study regarding the dependence of
the physical observables on the coarse-graining scheme. This results in
error-bars for the regularisation scheme (RS) dependence. We find quantitative
evidence for an intimate link between the RS dependence and truncations of flow
equations.


title: Axion Searches

abstract:
  The strong CP problem and its resolution through the existence of an axion
are briefly reviewed. The constraints on the axion from accelerator searches,
from the evolution of red giants and from supernova SN1987a combine to require
$m_a < 3 \cdot 10^{-3}$ eV, where $m_a$ is the axion mass. On the other hand,
the constraint that axions do not overclose the universe implies $m_a \gtwid
10^{-6}$ eV. If $m_a \sim 10^{-5}$ eV, axions contribute significantly to the
cosmological energy density in the form of cold dark matter. Dark matter axions
can be detected by resonant conversion to microwave photons in a cavity
permeated by a static magnetic field and tuned to the axion mass. Experiments
using this effect are described, as well as several other types of axion
searches.


title:
Explicit SO(10) Supersymmetric Grand Unified Model for the Higgs and
  Yukawa Sectors

abstract:
  A complete set of fermion and Higgs superfields is introduced with
well-defined SO(10) properties and U(1) x Z_2 x Z_2 family charges from which
the Higgs and Yukawa superpotentials are constructed. The structures derived
for the four Dirac fermion and right-handed Majorana neutrino mass matrices
coincide with those previously obtained from an effective operator approach.
Ten mass matrix input parameters accurately yield the twenty masses and mixings
of the quarks and leptons with the bimaximal atmospheric and solar neutrino
vacuum solutions favored in this simplest version.


title:
Coherent Contributions of Nuclear Mesons to Electroproduction and the
  HERMES Effect

abstract:
  We show that nuclear sigma, omega, and pi mesons can contribute coherently to
enhance the electroproduction cross section on nuclei for longitudinal virtual
photons at low Q^2 while depleting the cross section for transverse photons. We
are able to describe recent HERMES inelastic lepton-nucleus scattering data at
low Q^2 and small x using photon-meson and meson-nucleus couplings which are
consistent with (but not determined by) existing constraints from meson decay
widths, nuclear structure, deep inelastic scattering, and lepton pair
production data. We find that while nuclear-coherent pion currents are not
important for the present data, they could be observed at different kinematics.
Our model for coherent meson electroproduction requires the assumption of
mesonic currents and couplings which can be verified in separate experiments.
The observation of nuclear-coherent mesons in the final state would verify our
theory and allow the identification of a specific dynamical mechanism for
higher-twist processes.


title: The Proton Spin Puzzle: A Status Report

abstract:
  The proton spin puzzle inspired by the EMC experiment and its present status
are closely examined. Recent experimental progress is reviewed. Various
factorization schemes due to the ambiguity arising from the axial anomaly are
discussed. Some misconceptions in the literature about the $\MS$ factorization
scheme are clarified. It is stressed that the polarized nucleon structure
function $g_1(x)$ is independent of the factorization scheme chosen in defining
the quark spin density. Consequently, the anomalous gluon and sea-quark
interpretations for the deviation of the observed first moment of $g_1^p(x)$
from the Ellis-Jaffe sum rule are equivalent. While it is well known that the
total quark spin in the chiral-invariant (CI) factorization scheme (e.g. the
improved parton model) can be made to be close to the quark model expectation
provided that the gluon spin is positive and large enough, it is much less
known that, contrary to the gauge-invariant scheme (e.g. the MSbar scheme), the
quark orbital angular momentum in the CI scheme deviates even farther from the
relativistic quark model prediction. Recent developments in the NLO analysis of
polarized DIS data, orbital angular momentum and lattice calculations of the
proton spin content are briefly sketched.


title: Theory of Light Hydrogenlike Atoms

abstract:
  The present status and recent developments in the theory of light hydrogenic
atoms, electronic and muonic, are extensively reviewed. The discussion is based
on the quantum field theoretical approach to loosely bound composite systems.
The basics of the quantum field theoretical approach, which provide the
framework needed for a systematic derivation of all higher order corrections to
the energy levels, are briefly discussed. The main physical ideas behind the
derivation of all binding, recoil, radiative, radiative-recoil, and
nonelectromagnetic spin-dependent and spin-independent corrections to energy
levels of hydrogenic atoms are discussed and, wherever possible, the
fundamental elements of the derivations of these corrections are provided. The
emphasis is on new theoretical results which were not available in earlier
reviews. An up-to-date set of all theoretical contributions to the energy
levels is contained in the paper. The status of modern theory is tested by
comparing the theoretical results for the energy levels with the most precise
experimental results for the Lamb shifts and gross structure intervals in
hydrogen, deuterium, and helium ion $He^+$, and with the experimental data on
the hyperfine splitting in muonium, hydrogen and deuterium.


title: Model of Large Mixing Angle MSW Solution

abstract:
  We have obtained the neutrino mass matrix with the large mixing angle (LMA)
MSW solution,
  $\sin^2 2\th_\odot=0.65\sim 0.97$ and $\Delta m_{\odot}^2= 10^{-5}\sim
10^{-4}\eV^2$, in the $S_{3L}\times S_{3R}$ flavor symmetry. The structure of
our neutrino mass matrix is found to be stable against radiative corrections.