arXiv papers from November 1995

Leonard Susskind, John Uglum

In these lectures we review the quantum physics of large Schwarzschild black holes. Hawking's information paradox, the theory of the stretched horizon and the principle of black hole complementarity are covered. We then discuss how the ideas of black hole complementarity may be realized in string theory. Finally, arguments are given that the world may be a h

S. Drożdż, A. Trellakis, J. Wambach

The fluctuation properties of nuclear giant resonance spectra are studied in the presence of continuum decay. The subspace of quasi-bound states is specified by one-particle one-hole and two-particle two-hole excitations and the continuum coupling is generated by a scattering ensemble. It is found that, with increasing number of open channels, the real parts

Stephen Parke

In this talk I will summarize the latest experimental results from the four solar neutrino experiments and discuss what this means for the flux of $^7Be$ and $^8B$ neutrinos. The implications for the solar models including the new versions with helium and heavy element diffusion will also be addressed. The exciting and important calibration results of the Ga

I. A. Taimanov

Totally geodesically embeddings of infinitely many closed 7-manifolds into 13-dimensional positively curved closed Riemannian manifolds are constructed. The problems of computing pinching constants and existence of other totally geodesical embeddings are discussed.

A. Bahri, I. A. Taimanov

We consider a periodic problem for the motion of a charged particle in a magnetic field. Introducing a notion of Ricci curvature for such Lagrangian systems and using the methods of the calculus of variations in the large, we prove the existence of periodic motions for such particles under a condition of positivity of the Ricci curvature.

C. W. Kim, T. H. Lee, J. Song

A scale-dependent cosmology is proposed in which the Robertson-Walker metric and the Einstein equation are modified in such a way that $\Omega_0$, $H_0$ and the age of the Universe all become scale-dependent. Its implications on the observational cosmology are discussed.

Arnold Zellner

A Bayesian method of moments/instrumental variable (BMOM/IV) approach is developed and applied in the analysis of the important mean and multiple regression models. Given a single set of data, it is shown how to obtain posterior and predictive moments without the use of likelihood functions, prior densities and Bayes' Theorem. The posterior and predictive mo

Stephen Parke

I review standard top quark production at the Fermilab Tevatron. The current theoretical understanding of the total cross section and many partial differential cross sections is presented. Studies on the effects of extra gluon radiation on the top quark mass determination are reviewed. The possibility of new mechanisms for $t\bar{t}$ production are also disc

V. Barger, M. S. Berger, R. J. N. Phillips, T. W"ohrmann

We study the evolution of $R$-parity-violating (RPV) couplings in the minimum supersymmetric standard model, between the electroweak and grand unification scales, assuming a family hierarchy for these coupling strengths. Particular attention is given to solutions where both the $R$-conserving and $R$-violating top quark Yukawa couplings simultaneously approa

A. Smilga, J. J. M. Verbaarschot

We evaluate the leading infrared behavior of the scalar susceptibility in QCD and in the multiflavor Schwinger model for small non-zero quark mass $m$ and/or small nonzero temperature as well as the scalar susceptibility for the finite volume QCD partition function. In QCD, it is determined by one-loop chiral perturbation theory, with the result that the lea

Peter E. Haagensen, Kenneth Johnson, C. S. Lam

In a previous publication [1], local gauge invariant geometric variables were introduced to describe the physical Hilbert space of Yang-Mills theory. In these variables, the electric energy involves the inverse of an operator which can generically have zero modes, and thus its calculation is subtle. In the present work, we resolve these subtleties by conside

A. de la Macorra, S. Lola

We study inflationary potentials in the framework of superstring theories. Successful inflation may occur due to chiral fields, but only after the dilaton and moduli are stabilized. This is achieved by demanding an S-duality invariant potential. Then, it is possible to have inflation at any scale and even to have more than one stages of inflation. This occur

Edwin J. Beggs, Peter R. Johnson

In this note we show that the single soliton solutions known previously in the $1+1$ dimensional affine Toda field theories from a variety of different methods \cite{H1,MM,OTUa,OTUb}, are in fact not the most general single soliton solutions. We exhibit single soliton solutions with additional small parameters which reduce to the previously known solutions w

M. Bershadsky, V. Sadov, C. Vafa

In the presence of a D-brane a string theory develops a new subsector. We show that for curved D-branes the corresponding sector is a (partially twisted) topological field theory. We use this result to compute the degeneracy of 2-branes wrapped around $K3$ cycles as well as 3-branes wrapped around CY threefold vanishing 3-cycles. In both cases we find the de

The E143 Collaboration, K. Abe et al

The ratio g1/F1 has been measured over the range 0.03<x<0.6 and 0.3<Q2<10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized protons and deuterons. We find g1/F1 to be consistent with no Q2-dependence at fixed x in the deep-inelastic region Q^2>1 (GeV/c)2. A trend is observed for g1/F1 to decrease at lower Q2. Fits to world data w

Abhay Ashtekar

Using a key observation due to Thiemann, a generalized Wick transform is introduced to map the constraint functionals of Riemannian general relativity to those of the Lorentzian theory, including matter sources. This opens up a new avenue within ``connection-dynamics'' where one can work, throughout, only with real variables. The resulting quantum theory wou

M. Shifman

The values of $\alpha_s$ determined from low- and high-energy measurements are in irreconcilable contradiction with each other. The current status of the problem is critically reviewed. Consequences of the $\alpha_s$ contradiction, in conjunction with other anomalies detected at the $Z$ peak, are discussed. The write-up is updated in accordance with experime

Ahmed Hindawi, Burt A. Ovrut, Daniel Waldram

We construct two classes of higher-derivative supergravity theories generalizing Einstein supergravity. We explore their dynamical content as well as their vacuum structure. The first class is found to be equivalent to Einstein supergravity coupled to a single chiral superfield. It has a unique stable vacuum solution except in a special case, when it becomes

V. A. Miransky

A constant magnetic field in 3+1 and 2+1 dimensions is a strong catalyst of dynamical chiral symmetry breaking, leading to the generation of a fermion mass even at the weakest attractive interaction between fermions. The essence of this effect is the dimensional reduction $D/rightarrow D-2$ in the dynamics of fermion pairing in a magnetic field. The effect i

P. Fernández de Córdoba, E. Marco, H. Müther, E. Oset

The nuclear structure function F_2A(x) has been studied in the Bjorken limit for (l, l') scattering on nuclei in the region of x > 1 and was found to be very sensitive to the information contained in the nucleon spectral function in nuclei, particularly the correlations between momenta and energies in the region of large momenta. Calculations were done in a

Stephen Parke

The production cross--section and distributions of the top quark are sensitive to new physics, e.g., the $t\overline{t}$ system can be a probe of new resonances or gauge bosons that are strongly coupled to the top quark, in analogy to Drell--Yan production. The existence of such new physics is expected in dynamical electroweak symmetry breaking schemes, and

Nivaldo A. Lemos

Radiation-filled Friedmann-Robertson-Walker universes are quantized according to the Arnowitt-Deser-Misner formalism in the conformal-time gauge. Unlike previous treatments of this problem, here both closed and open models are studied, only square-integrable wave functions are allowed, and the boundary conditions to ensure self-adjointness of the Hamiltonian

CLEO Collaboration

Using the angular correlation between the $\pi^+$ emitted in a $D^{*+} \rightarrow D^0 \pi^+$ decay and the $e^+$ emitted in the subsequent $D^0 \rightarrow Xe^+\nu$ decay, we have measured the branching fraction for the inclusive semi-electronic decay of the $D^0$ meson to be: {\cal B}(D^0 \rightarrow X e^+ \nu) = [6.64 \pm 0.18 (stat.) \pm 0.29 (syst.)] \%

V. Jeudy, J. I. Collar, T. A. Girard, D. Limagne

We report the first energy loss spectrum obtained with a geometrically metastable type I superconducting tin strip irradiated by the beta-emission of S-35. (Nucl. Instr. Meth. A, in press)

C. D. Fosco

The overlap formulation is applied to calculate the chiral determinant on a two-dimensional torus with twisted boundary conditions. We evaluate first the continuum overlap, which is convergent and well-defined, and yields the correct string theory result for both the real and imaginary parts of the effective action. We then show that the lattice version of t

Franco Ruggeri, William Friedman

We evaluate the factor $\kappa$ appearing in Langer's expression for the nucleation rate extended to the case of hadron bubbles forming in zero baryon number cooled quark-gluon plasma. We consider both the absence and presence of viscosity and show that viscous effects introduce only small changes in the value of $\kappa$

Zhenping Li, Ron Workman

We review the status of the $S_{11}$ N$^*$ resonances in light of some recent theoretical and phenomenological results. Whereas the quark model predicts two such resonances around 1.6 GeV, there is considerable evidence for a third $S_{11}$ resonance in this energy range. This suggests that a $K\Sigma$ or $K\Lambda$ quasi-bound state may indeed exist below t

T. Binoth, J. J. van der Bij

The influence of massless scalar singlets on the Higgs signal at LEP2 is discussed. It is shown that for strong interactions between the Higgs boson and the singlet fields, detection of the Higgs signal can become impossible.

Debajyoti Choudhury

We investigate the ability of LEP2 to detect possible $R$-parity violation, especially for the case where direct production cross-sections are too small for all superparticles. We demonstrate that for coupling strengths allowed by present experiments, sfermion-exchange diagrams can contribute significantly to the $e^+ e^- \rightarrow f \bar{f} $ process. Thi

Greg Keaton, Ron Workman

We consider the problem of determining amplitudes from observables for the case of pseudoscalar meson photoproduction. We find a number of surprisingly simple constraints which give necessary conditions for a complete set of measurements. These results contradict one of the selection rules derived previously.

T. Kloesch, T. Strobl

A set of simple rules for constructing the maximal (e.g. analytic) extensions for any metric with a Killing field in an (effectively) two-dimensional spacetime is formulated. The application of these rules is extremely straightforward, as is demonstrated at various examples and illustrated with numerous figures. Despite the resulting simplicity we also comme

T. Alm, G. Roepke, A. Schnell, N. H. Kwong

Nucleon selfenergies and spectral functions are calculated at the saturation density of symmetric nuclear matter at finite temperatures. In particular, the behaviour of these quantities at temperatures above and close to the critical temperature for the superfluid phase transition in nuclear matter is discussed. It is shown how the singularity in the thermod

M. Anazawa, H. Itoyama

We investigate the structure of the macroscopic $n$-loop amplitude obtained from the two-matrix model at the unitary minimal critical point $(m+1,m)$. We derive a general formula for the $n$-resolvent correlator at the continuum planar limit whose inverse Laplace transform provides the amplitude in terms of the boundary lengths $\ell_{i}$ and the renormalize

A. Pich, E. de Rafael

It is shown that there exist symmetry constraints for non--leptonic weak amplitudes which emerge when the $1/N_c$--expansion restricted to the leading and next--to--leading approximations only is systematically combined with $\chi$PT limited to the lowest non--trivial order. We discuss these constraints for the couplings $\mbox{\bf g}_8$ and $\mbox{\bf g}_{2

Gautam Mandal, Spenta R. Wadia

We probe the geometry around an elementary BPS (EBPS) state in heterotic string theory compactified on a six-torus by scattering a massless scalar off it and comparing with the corresponding experiment in which the EBPS state is replaced by a classical extremal black hole background satisfying the BPS condition. We find that the low energy limit of the scatt

Hans-Thomas Elze

Entropy production in quantum (field) systems requiring environment-induced decoherence is described in a Gaussian variational approximation. The new phenomenon of Semiquantum Chaos is reported. (Presented at the International Conference on Nonlinear Dynamics, Chaotic and Complex Systems, Zakopane (Poland), 7-12.11.95.)

R. Loll

We describe recent attempts at discretizing canonical quantum gravity in four dimensions in terms of a connection formulation. This includes a general introduction, a comparison between the real and complex connection approach, and a discussion of some open problems. (Contribution to the proceedings of the workshop ``Recent mathematical developments in class

M. D'Agostino, P. F. Mastinu, P. M. Milazzo, M. Bruno

Multifragment disintegration has been measured with a high efficiency detection system for the reaction $Au + Au$ at $E/A = 35\ MeV$. From the event shape analysis and the comparison with the predictions of a many-body trajectories calculation the data, for central collisions, are compatible with a fast emission from a unique fragment source.

D. S. Henty, C. Parrinello, D. G. Richards

We investigate the Landshoff-Nachtmann two-gluon-exchange model of the Pomeron using gluon propagators computed in the Landau gauge within quenched lattice QCD calculations. We first determine an effective gluon-quark coupling by constraining the Pomeron-quark coupling to its phenomenological value $\beta_0 = 2\, \gev^{-1}$. We then provide predictions for a

N. V. Krasnikov

We show that in supersymmetric models with explicit flavor lepton number violation due to soft supersymmetry breaking terms there must be flavor lepton number violation in slepton decays. We propose to look for flavor lepton number violation in righthanded selectron and smuon decays. For selectron and smuon lighter than 80 Gev flavor lepton number violation

Leonid P. Pryadko, Shou-Cheng Zhang

By mapping the relativistic version of the Chern-Simons-Landau-Ginzburg theory in 2+1 dimensions to the 3D lattice Villain x-y model coupled with the Chern-Simons gauge field, we investigate phase transitions of Chern-Simons bosons in the limit of strong coupling. We construct algebraically exact duality and flux attachment transformations of the lattice the

Takao Nakamura, Shinji Hamamoto

Path integral expressions for three canonical formalisms -- Ostrogradski's one, constrained one and generalized one -- of higher-derivative theories are given. For each fomalism we consider both nonsingular and singular cases. It is shown that three formalisms share the same path integral expressions. In paticular it is pointed out that the generalized canon

H. Kawai, Y. Kitazawa, M. Ninomiya

We study the renormalizability of quantum gravity near two dimensions. Our formalism starts with the tree action which is invariant under the volume preserving diffeomorphism. We identify the BRS invariance which originates from the full diffeomorphism invariance. We study the Ward-Takahashi identities to determine the general structure of the counter terms.

Andrey V. Chubukov, Dirk K. Morr, Konstantin A. Shakhnovich

We consider a two-dimensional Fermi liquid coupled to low-energy commensurate spin fluctuations. At small coupling, the hole Fermi surface is large and centered around $(\pi,\pi)$. We show that as the coupling increases, the shape of the Fermi surface undergoes a substantial evolution, and at strong coupling, the hole Fermi surface consists of small pockets

Yi Liao, Yu-Ping Kuang, Chong-Sheng Li

We show that the naively expected large virtual heavy fermion effects in low energy processes may be screened if the process under consideration contains external gauge bosons constrained by gauge invariance. We illustrate this by a typical example of the process $\gamma\gamma\to b \bar{b}$. Phenomenological implications are also briefly indicated.

Sumit R. Das

We discuss two issues regarding the question of degrees of freedom in two dimensional string theory. The first issue relates to the classical limit of quantum string theory. In the classical theory one requires an infinite number of fields in addition to the collective field to describe ``folds'' on the fermi surface. We argue that in the quantum theory thes

Sangita N. Pitre, Joris Van der Jeugt

The double hypergeometric Kamp\'e de F\'eriet series $F^{0:3}_{1:1}(1,1)$ depends upon 9 complex parameters. We present three cases with 2 relations between those 9 parameters, and show that under these circumstances $F^{0:3}_{1:1}(1,1)$ can be written as a ${}_4F_3(1)$ series. Some limiting cases of these transformation formulas give rise to new summation r

J. Baldwin, R. Grossberg, Saharon Shelah

Saturation is (mu,kappa)-transferable in T if and only if there is an expansion T_1 of T with |T_1| = |T| such that if M is a mu-saturated model of T_1 and |M| \geq kappa then the reduct M|L(T) is kappa-saturated. We characterize theories which are superstable without the finite cover property (f.c.p.), or without f.c.p. as, respectively those where saturati

G. Baskaran

In the interlayer pair tunneling (ILPT) theory of superconductivity the large scale $T_c$ has its origin in the k-space locality of the inter layer pair tunneling matrix elements. We reinterpret the same physics as a process of resonant pair tunneling and illustrate it through cooper pair analysis. This interpretation is used to give a mechanism which leads

G. Varelogiannis

We point out that in two-dimensional systems like high-$T_c$ superconductors, an isotropic s-wave electron-phonon interaction in the momentum decoupling regime leads to either s or d-wave superconductivity depending on the conventional values of the Coulomb pseudopotential. It is therefore possible that $YBa_2Cu_3O_7$ is an anisotropic d-wave and $Bi_2Sr_2Ca

Julio F. Navarro

I review the results of recent N--body/hydrodynamical simulations of the formation of galaxies in hierarchical universes, with special emphasis on the structure of dark matter halos, as well as on the mass and angular momentum of gaseous disks that assemble at the center of these halos.

Max Tegmark

The power spectrum of fluctuations in the cosmic microwave background (CMB) depends on most of the key cosmological parameters. Accurate future measurements of this power spectrum might therefore allow us to determine h, Omega, Omega_b, Lambda, n, T/S, etc, with hitherto unprecedented accuracy. In these lecture notes, which are intended to be readable withou

G. Camelo-Neto, S. Coutinho

The steady state properties of the mean density population of infected cells in a viral spread is simulated by a general forest fire like cellular automaton model with two distinct populations of cells ( permissive and resistant ones) and studied in the framework of the mean field approximation. Stochastic dynamical ingredients are introduced in this model t

D. R. Davidson

In the theory of nets of observable algebras, the modular operators associated with wedge regions are expected to have a natural geometric action, a generalization of the Bisognano-Wichmann condition for nets associated with Poincare-covariant fields. Here many possible such modular covariance conditions are discussed (in spacetime of at least three dimensio

N. G. Deshpande, Xiao-Gang He, Sechul Oh

We study the influence of penguin (especially, electroweak penguin) effects on some methods of measuring the angles $\alpha$, $\beta$, and $\gamma$ in the CKM unitarity triangle. We use next-to-leading order effective Hamiltonian, and present numerical estimates based on the factorization approximation. We find that some techniques suggested in the literatur

D. B. Lichtenberg, R. Roncaglia, E. Predazzi

Regularities in the hadron interaction energies are used to obtain formulas relating the masses of ground-state hadrons, most of which contain heavy quarks. Inputs are the constituent quark model, the Feynman-Hellmann theorem, and the structure of the colormagnetic interaction of QCD. Some of the formulas can also be obtained from heavy quark effective theor

Cecilia Noguez, Sergio E. Ulloa

The optical properties of the 2$\times$1 reconstruction of the diamond (111) surface are investigated. The electronic structure and optical properties of the surface are studied using a microscopic tight-binding approach. We calculate the dielectric response describing the surface region and investigate the origin of the electronic transitions involving surf

R. Rosenfeld, L. A. Barreiro, C. O. Escobar, M. Nielsen

We investigate the impact of new physics beyond the Standard Model to the $s \rightarrow d \gamma$ process, which is responsible for the short-distance contribution to the radiative decay $\Otogamma$. We study three representative extensions of the Standard Model, namely a one-family technicolor model, a two Higgs doublet model and a model containing scalar

William H. Kinney, K. T. Mahanthappa

We investigate general scalar field potentials \hbox{$V\left(\phi\right)$} for inflationary cosmology arising from spontaneous symmetry breaking. We find that potentials which are dominated by terms of order $\phi^m$ with \hbox{$m > 2$} can satisfy observational constraints at an arbitrary symmetry breaking scale. Of particular interest, the spectral index o

V. Barger, P. G. Mercadante, R. J. N. Phillips

We calculate top pair production and decay at the Tevatron $p\bar p$ collider, with the emission of an extra gluon, and study the corresponding $W+5$\,jet top signals including full spin correlations in the $W \to \ell\nu$ leptonic and $W\to jj$ hadronic decays. We study the feasibility of reconstructing $W+5$\,jet top events with a single $b$-tag, including

Sumne Kim, F. Mansouri

By an extension of the methods used for the reduction of the two body problem in 2+1 dimensional gravity, we show that the two body problem in N=2 Chern Simons supergravity can be reduced exactly to an equivalent on body formalism. We give exact expressions for the invariants of the reduced one body problem.

A. Dullweber, E. R. Hilf, E. Mendel

The path integral formalism gives a very illustrative and intuitive understanding of quantum mechanics but due to its difficult sum over phases one usually prefers Schr\"odinger's approach. We will show that it is possible to calculate simple quantum phenomena by performing Feynman's sum over all paths staying entirely in real time. Once the propagator is ob

Ben Moore

The detection of stars in the process of being tidally removed from globular clusters and dwarf spheroidals in the Galaxy's halo provides a strong constraint on their mass to light ratios and on the extent of their possible dark matter halos. If a significant dark matter component existed either within or beyond the observed stellar distribution, then stars

N. Banerjee, R. Banerjee

We convert the second class Proca model into a first class theory by using the generalised prescription of Batalin, Fradkin and Tyutin. We then show how a basic set of gauge invariant fields in the embedded model can be identified with the fundamental fields in the proca model as well as with the observables in the St\"uckelberg model or in the model involvi

Philip Resnik

This paper presents a new measure of semantic similarity in an IS-A taxonomy, based on the notion of information content. Experimental evaluation suggests that the measure performs encouragingly well (a correlation of r = 0.79 with a benchmark set of human similarity judgments, with an upper bound of r = 0.90 for human subjects performing the same task), and

Philip Resnik

Word groupings useful for language processing tasks are increasingly available, as thesauri appear on-line, and as distributional word clustering techniques improve. However, for many tasks, one is interested in relationships among word {\em senses}, not words. This paper presents a method for automatic sense disambiguation of nouns appearing within sets of

R. D. Benguria, M. C. Depassier

We study the speed of propagation of fronts for the scalar reaction-diffusion equation $u_t = u_{xx} + f(u)$\, with $f(0) = f(1) = 0$. We give a new integral variational principle for the speed of the fronts joining the state $u=1$ to $u=0$. No assumptions are made on the reaction term $f(u)$ other than those needed to guarantee the existence of the front. T

C. L. Wu, M. Guidry, D. H. Feng

The recent discovery of isotopes with Z=110--111 suggests evidence for (1) a monopole--monopole interaction that does not appear explicitly in Nilsson--Strutinsky mass systematics, and (2) a competition between $SU(2)$ and $SU(3)$ dynamical symmetries that has been predicted for this region. Our calculations suggest that these new isotopes are near spherical

The E143 Collaboration, K. Abe et al

We have measured proton and deuteron virtual photon-nucleon asymmetries A2p and A2d and structure functions g2p and g2d over the range 0.03<x<0.8 and 1.3<Q2<10 (GeV/c)2 by inelastically scattering polarized electrons off polarized ammonia targets. Results for A2 are significantly smaller than the positivity limit sqrt(R) for both targets. Within experimental

Eduardo Mendel, Guido Nolte

Based on the study of the simple Abelian Higgs model in $1+1$ dimensions we will present a new method to identify and localize extended instantons. The idea is to measure the topological charge on regions somewhat larger than the extended instantons so as to average out the ultraviolet fluctuations but without losing the detailed topological information when

R. K. Kamilla, X. G. Wu, J. K. Jain

The low energy neutral excitations of incompressible fractional quantum Hall states are called collective modes or magnetic excitons. This work develops techniques for computing their dispersion at general filling fractions for reasonably large systems. New structure is revealed; in particular, the collective mode at 1/3 is found to possess several minima, w

N. Mohan Kumar

Many examples of rank two bundles on ${\bf P}^4$ are constructed in positive characteristic. Construction depends on constructing certain special bundles on ${\bf P}^3$ which is shown to be equivalent to constructing bundles on ${\bf P}^4$ (in any characteristic). In fact this is true for projective spaces of any dimension.

Supriya Kar, Jnanadeva Maharana, Sudhakar Panda

We consider an eleven dimensional supergravity compactified on $K3\times T^2$ and show that the resulting five dimensional theory has identical massless states as that of heterotic string compactified on a specific five torus $T^5$. The strong-weak coupling duality of the five dimensional theory is argued to represent a ten dimensional Type $IIA$ string comp

Joseph D. Lykken

These lectures from the 1995 Trieste Summer School in High Energy Physics and Cosmology give an elementary introduction to perturbative superstring theory, superstring phenomenology, and the fermionic construction of perturbative string models.These lectures assume no prior knowledge of string theory.

Hans - Juergen Schmidt

The use of time--like geodesics to measure temporal distances is better justified than the use of space--like geodesics for a measurement of spatial distances. We give examples where a ''spatial distance'' cannot be appropriately determined by the length of a space--like geodesic.

Hans - Juergen Schmidt

The following four statements have been proven decades ago already, but they continue to induce a strange feeling: - All curvature invariants of a gravitational wave vanish - in spite of the fact that it represents a nonflat spacetime. - The eigennullframe components of the curvature tensor (the Cartan ''scalars'') do not represent curvature scalars. - The E

T. Gruner, D. -G. Welsch

Using the Green function approach to the problem of quantization of the phenomenological Maxwell theory, the propagation of quantized radiation through dispersive and absorptive multilayer dielectric plates is studied. Input--output relations are derived, with special emphasis on the determination of the quantum noise generators associated with the absorptio

Christian Holm, Wolfhard Janke

We use Monte Carlo simulations to study pure 2D Euclidean quantum gravity with $R^2$-interaction on spherical topologies, employing Regge's formulation. We attempt to measure the string susceptibility exponent $\gamma_{\rm str}$ by using a finite-size scaling Ansatz in the expectation value of $R^2$, as has been done in a previous study by Bock and Vink ( he

Wolfgang Ochs, Jacek Wosiek

The angular correlation function of partons in a jet, as derived from perturbative QCD, is nonanalytic at a critical angle which separates a multiparticle regime with scaling properties from a regime with few particles near the hadronisation scale. Some phenomenological consequences are discussed.

David Merritt

In any collisionless N-body code, there is an optimal choice for the smoothing parameter that minimizes the average error in the force evaluations. We show how to compute the optimal softening length in a direct-summation code and demonstrate that it varies roughly as 1/N^(1/3).

M. Daoud, M. Kibler

Magnetic- and electric-dipole two-photon absorption (MED-TPA), recently introduced as a new spectroscopic technique for studying transitions between states of opposite parities, is investigated from a theoretical point of view. A new approximation, referred to as {\it weak quasi-closure approximation}, is used together with symmetry adaptation techniques to

B. Bajc, S. Fajfer, R. J. Oakes

We analyze charm meson semileptonic decays using the measured ratios $\Gamma_L/\Gamma_T$ and $\Gamma_{+}/\Gamma_{-}$ from $D\to {\bar K}^{*}$ and the branching ratios for $D \to {\bar K}^{*}$ and $D \to {\bar K}$. First we introduce the light vector mesons in a model which combines the heavy quark effective Lagrangian and the chiral perturbation approach. We

Adam F. Falk, Michael Luke, Martin J. Savage

We apply a recent theoretical analysis of hadronic observables in inclusive semileptonic heavy hadron decays to the phenomenology of $B$ and $D$ mesons. Correlated bounds on the nonperturbative parameters $\bar\Lambda$ and $\lambda_1$ are derived by considering data from $B$ decays and, independently, data from $D$ decays. The two sets of bounds are found to

O. K. Vorov

Mean square matrix elements of the time reversal invariance violating (TRIV) interaction between the compound nuclear states are calculated within the statistical model, using the explicit form of the TRIV interaction via the $\rho$-meson exchange. From the comparison of the calculated values with the data known for $p+ ^{27}Al \Leftrightarrow ^{24}Mg + \alp

Arild Skjold, Per Osland

In a more general electroweak theory, there could be Higgs particles that are odd under $CP$. When such particles decay via vector bosons to two fermion-antifermion pairs, the momenta of those will be correlated in a way which is determined by the $CP$ of the particle. Similarly, in the Bjorken process correlations among momenta of the initial electron and f

P. Kroll

The present status of applications of perturbative QCD to large momentum transfer exclusive reactions is discussed. It is argued that in the region of momentum transfer accessible to present day experiments soft contributions dominate the exclusive processes.

Max Welling

In these notes we will review some approaches to 2+1 dimensional gravity and the way it is coupled to point-particles. First we look into some exact static and stationary solutions with and without cosmological constant. Next we study the polygon approach invented by 't Hooft. The third section treats the Chern-Simonons formulation of 2+1-gravity. In the las

B. Basu-Mallick, P. Ramadevi, R. Jagannathan

Inspired by Reshetikhin's twisting procedure to obtain multiparametric extensions of a Hopf algebra, a general `symmetry transformation' of the `particle conserving' $R$-matrix is found such that the resulting multiparametric $R$-matrix, with a spectral parameter as well as a colour parameter, is also a solution of the Yang-Baxter equation (YBE). The corresp

Beatriz Gato-Rivera, Jose Ignacio Rosado

Recently we showed that the spectral flow acting on the N=2 twisted topological theories gives rise to a topological algebra automorphism. Here we point out that the untwisting of that automorphism leads to a spectral flow on the untwisted N=2 superconformal algebra which is different from the usual one. This "other" spectral flow does not interpolate betwee

Romuald Janik

We identify a new symmetry for the equations governing odderon amplitudes, corresponding in the Regge limit of QCD to the exchange of 3 reggeized gluons. The symmetry is a modular invariance with respect to the unique normal subgroup of sl(2,Z) {\,} of index 2. This leads to a natural description of the Hamiltonian and conservation-law operators as acting on

A. Bellini, M. Ciafaloni, P. Valtancoli

We construct a non-perturbative, single-valued solution for the metric and the motion of $N$ interacting particles in $2+1$-Gravity. The solution is explicit for two particles with any speed and for any number of particles with small speed. It is based on a mapping from multivalued Minkowskian coordinates to single-valued ones, which solves the non-abelian m

R. Guida, N. Magnoli

We consider here renormalizable theories without relevant couplings and present an I.R. consistent technique to study corrections to short distance behavior (Wilson O.P.E. coefficients) due to a relevant perturbation. Our method is the result of a complete reformulation of recent works on the field, and is characterized by a more orthodox treatment of U.V. d

Richard Easther

We present a new, exact scalar field cosmology for which the spectrum of scalar (density) perturbations can be calculated exactly. We use this exact result to the probe the accuracy of approximate calculations of the perturbation spectrum.

M. Thies

We review a recent attempt to deal with non-perturbative features of QCD by analytical means, using a manifestly gauge invariant, canonical approach.

Walter T. Giele, Stephane Keller, Eric Laenen

The next-to-leading order QCD corrections to the production of a $W$-boson in association with a jet containing a heavy quark are presented. The calculation is fully differential in the final state particle momenta and includes the mass of the heavy quark. We study for the case of the Tevatron the sensitivity of the cross section to the strange quark distrib

H1-Collaboration, S. Aid et al

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to $\overline{p}p$ data and QCD calculations. The comparisons show that the $\gamma p$ events can be consistently described by QCD

Erwin Mirkes, Dieter Zeppenfeld

Two-jet cross sections in deep inelastic scattering at HERA are calculated in next-to-leading order. The QCD corrections are implemented in a new $ep\rightarrow n$ jets event generator, MEPJET, which allows to analyze arbitrary jet definition schemes and general cuts in terms of parton 4-momenta. First results are presented for the JADE, the cone and the $k_

Masao Jinzenji

Using the torus action method, we construct one variable polynomial representation of quantum cohomology ring for degree $k$ hypersurface in $CP^{N-1}$ . The results interpolate the well-known result of $CP^{N-2}$ model and the one of Calabi-Yau hypersuface in $CP^{N-1}$. We find in $k\leq N-2$ case, principal relation of this ring have very simple form comp

Gautam Bhattacharyya

Electroweak precision data at LEP are used to place bounds on some $\lambda'$-type ($L$-violating) and $\lambda''$-type ($B$-violating) $R$-parity violating supersymmetric Yukawa couplings. We consider one-loop corrections (triangles and self-energies) induced by these couplings to the $Z$-partial widths. The couplings involving the top quark induce stronger

S. Hirenzaki, P. Fernández de Córdoba, E. Oset

We study the Roper excitation in the $(\alpha,\alpha')$ reaction. We consider all processes which may be relevant in the Roper excitation region, namely, Roper excitation in the target, Roper excitation in the projectile, and double $\Delta$ excitation processes. The theoretical investigation shows that the Roper excitation in the proton target mediated by a