May 1994 arXiv papers — page 3

M. Herrmann, G. F. Bertsch

Recent experiments on pion correlations, interpreted as interferometric measurements of the collision zone, are compared with models that distinguish a prehadronic phase and a hadronic phase. The models include prehadronic longitudinal expansion, conversion to hadrons in local kinetic equilibrium, and rescattering of the produced hadrons. We find that the lo

M. T. Ceballos, X. Barcons

The negative evolution found in X--ray clusters of galaxies limits the amount of available hot gas for the inverse Compton scattering of the Cosmic Microwave Background (the Sunyaev--Zel'dovich effect). Using a parametrisation of the X-ray luminosity function and its evolution in terms of a coalescence model (as presented in the analysis of a flux limite

Jamil Daboul, Michael Martin Nieto

After reviewing the general properties of zero-energy quantum states, we give the explicit solutions of the \seq with $E=0$ for the class of potentials $V=-|γ|/r^ν$, where $-\infty < ν< \infty$. For $ν> 2$, these solutions are normalizable and correspond to bound states, if the angular momentum quantum number $l>0$. [These states are normalizable, even for $

Colin J. Morningstar, Marvin Weinstein

The COntractor REnormalization group (CORE) method, a new approach to solving Hamiltonian lattice systems, is introduced. The method combines contraction and variational techniques with the real-space renormalization group approach. It applies to lattice systems of infinite extent and is ideal for studying phase structure and critical phenomena. The CORE app

V. K. Dobrev

We construct representations $\hatπ_{\br}$ of the quantum algebra $U_q(sl(n))$ labelled by $n-1$ complex numbers $r_i$ and acting in the space of formal power series of $n(n-1)/2$ non-commuting variables. These variables generate a flag manifold of the matrix quantum group $SL_q(n)$ which is dual to $U_q(sl(n))$. The conditions for reducibility of $\hatπ_{\b

James Rogers

We define a decidable class of TAGs that is strongly equivalent to CFGs and is cubic-time parsable. This class serves to lexicalize CFGs in the same manner as the LCFGs of Schabes and Waters but with considerably less restriction on the form of the grammars. The class provides a normal form for TAGs that generate local sets in much the same way that regular

Mihai Horoi, B. Alex Brown

The experimental PNC results in $^{18}$F, $^{19}$F, $^{21}$Ne and the current theoretical analysis show a discrepancy . If one interprets the small limit of the experimentally extracted PNC matrix element for $^{21}$Ne as a destructive interference between the isoscalar and the isovector contribution, then it is difficult to understand why the isovector cont

Christian Berg, Mourad E. H. Ismail

We use generating functions to express orthogonality relations in the form of $q$-beta integrals. The integrand of such a $q$-beta integral is then used as a weight function for a new set of orthogonal or biorthogonal

Narcisse Randrianantoanina

Let $X$ be a separable Banach space, $Y$ be a Banach space and $Λ$ be a subset of the dual group of a given compact metrizable abelian group. We prove that if $X^*$ and $Y$ have the type I-$Λ$-RNP (resp. type II-$Λ$-RNP) then $K(X,Y)$ has the type I-$Λ$-RNP (resp. type II-$Λ$-RNP) provided $L(X,Y)=K(X,Y)$. Some corollaries are then presented as well as resul

Alberto Marcone

In this paper we prove that the set of countable bqos (viewed as a subset of the Cantor space) is Pi^1_2-complete. The notion of bqo or better quasi-ordering arises from combinatorics and is a generalization of the canonical example of a Pi^1_1-complete notion, i.e. that of countable well-ordering. The Pi^1_2-completeness of bqo was conjectured by Clote and

Jürgen Fuchs, Beatriz Gato-Rivera, Bert Schellekens, Christoph Schweigert

We show that Galois theory of cyclotomic number fields provides a powerful tool to construct systematically integer-valued matrices commuting with the modular matrix S, as well as automorphisms of the fusion rules. Both of these prescriptions allow the construction of modular invariants and offer new insight in the structure of known exceptional invariants.

L. Burakovsky, L. P. Horwitz

The relativistic distribution for indistinguishable events is considered in the mass-shell limit $m^2\cong M^2,$ where $M$ is a given intrinsic property of the events. The characteristic thermodynamic quantities are calculated and subject to the zero-mass and the high-temperature limits. The results are shown to be in agreement with the corresponding express

J. M. F. Labastida, M. Marino

Perturbing usual type B topological matter with vector $(0,1)$-forms we find a topological theory which contains explicitly Kodaira-Spencer deformation theory. It is shown that, in genus zero, three-point correlation functions give the Yukawa couplings for a generic point in the moduli space of complex structures. This generalization of type B topological ma

K. S. Babu, Kiwoon Choi, J. C. Pati, X. Zhang

It is shown that the recently proposed preon model which provides a unified origin of the diverse mass scale and an explanation of family replication as well as of inter-family mass-hierarchy, possesses a Peccei-Quinn symmetry whose spontaneous breaking leads to an automatic invisible axion. Existence of the PQ-symmetry is simply a consequence of supersymmet

V. L. Eletsky, B. L. Ioffe

Corrections of order $T^4$ to vector and axial current correlators in QCD at a finite temperature $T<T_c$ are obtained using dispersion relations for the amplitudes of deep inelastic scattering on pions. Their relation with the operator product expansion is presented. An interpretation of the results in terms of $T$-dependent meson masses is given: masses of

L. Burakovsky, L. P. Horwitz

We find the equation of state $p,ρ\propto T^6,$ which gives the value of the sound velocity $c^2=0.20,$ in agreement with the ``realistic&#39;&#39; equation of state for hot hadronic matter suggested by Shuryak, in the framework of a covariant relativistic statistical mechanics of an event--anti-event system with small chemical and mass potentials. The relat

Ll. Ametller, Ll. Garrido, P. Talavera

We show that Neural Nets can be useful for top analysis at Tevatron. The main features of $t\bar t$ and background events on a mixed sample are projected in a single output, which controls the efficiency and purity of the $t\bar t$ signal.

A. J. Buras

We point out that the measurements of the CP asymmetries in neutral B-decays together with a measurement of $Br(K_L\to π^\circν\barν)$ and the known value of $\mid V_{us}\mid $ can determine {\it all} elements of the Cabibbo-Kobayashi-Maskawa matrix without essentially any hadronic uncertainties. In particular the strong dependence of $Br(K_L\to π^\circν\bar

G. Ingelman, J. Rathmans

The deep inelastic scattering 2+1 jet cross- section is a useful observable for precision tests of QCD, e.g. measuring the strong coupling constant alpha(s). A consistent analysis requires a good understanding of the theoretical uncertainties and one of the most fundamental ones in QCD is due to the renormalization scheme and scale ambiguity. Different metho

Michael P. MATTIS, Richard R. SILBAR

We review the large-N_c approach to meson-baryon scattering, including recent interesting developments. We then study pion-nucleon scattering in a particular variant of the linear sigma-model, in which the couplings of the sigma and pi mesons to the nucleon are echoed by couplings to the entire tower of I=J baryons (including the Delta) as dictated by large-

F. Di Renzo, G. Marchesini, P. Marenzoni, E. Onofri

We describe a stochastic technique which allows one to compute numerically the coefficients of the weak coupling perturbative expansion of any observable in Lattice Gauge Theory. The idea is to insert the exponential representation of the link variables $U_μ(x) \to \exp\{A_μ(x)/\sqrtβ\}$ into the Langevin algorithm and the observables and to perform the expa

G. Cella, G. Curci, A. Vicere&#39;, B. Vigna

We report on the determination of the deconfining temperature in SU(3) pure gauge theory, using the Symanzik tree level improved action, on lattices of size 3 x 12^3, 4 x 16^3, 5 x 20^3, 6 x24^3. We find that the asymptotic scaling violation pattern is similar to the one observed using the Wilson action. We conclude that the irrelevant operators do not affec

Alberto Saa

When space-time is assumed to be non-Riemannian the minimal coupling procedure (MCP) is not compatible, in general, with minimal action principle (MAP). This means that the equations gotten by applying MCP to the Euler-Lagrange equations of a Lagrangian $\cal L$ do not coincide with the Euler-Lagrange equations of the Lagrangian obtained by applying MCP to $

H Balasin, H Nachbagauer

The ultrarelativistic limit of the Schwarzschild and the Kerr-geometry together with their respective energy-momentum tensors is derived. The approach is based on tensor-distributions making use of the underlying Kerr-Schild structure, which remains stable under the ultrarelativistic boost.

J. Bonca, J. P. Rodriguez, J. Ferrer, K. S. Bedell

The spin-stiffness of frustrated spin-1/2 Heisenberg models in one and two dimensions is computed for the first time by exact diagonalizations on small clusters that implement spin-dependent twisted boundary conditions. Finite-size extrapolation to the thermodynamic limit yields a value of $0.14\pm 0.01$ for the spin-stiffness of the unfrustrated planar anti

K A Muttalib, Y Chen

We obtain the shot noise generating function for a multi-channel quantum conductor in the diffusive limit.

Y Chen, H J Jensen

The thermodynamics of interacting vortices constricted to move in one-dimensional tracks carved out on superconducting film in the extreme type-II limit is mapped onto the Coulomd gas model of random matrices.

A. S. Cattaneo, A. Gamba, I. V. Kolokolov

The set of moments and the distribution function of the one-electron current in a one-dimensional disordered ring with arbitrary magnetic flux are calculated.

D. Z. Liu, Ben Yu-Kuang Hu, C. A. Stafford, S. Das Sarma

Using a finite-frequency recursive Green&#39;s function technique, we calculate the dynamic magneto-conductance fluctuations and oscillations in disordered mesoscopic normal metal systems, incorporating inter-particle Coulomb interactions within a self-consistent potential method. In a disordered metal wire, we observe ergodic behavior in the dynamic conduct

Keith Vander Linden

This study employs a knowledge intensive corpus analysis to identify the elements of the communicative context which can be used to determine the appropriate lexical and grammatical form of instructional texts. \ig, an instructional text generation system based on this analysis, is presented, particularly with reference to its expression of precondition rela

C. P. Deliyannis, R. A. Malaney

Motivated by the recent report of a $^6$Li detection in the atmosphere of HD~84937, we couple stellar evolution calculations with light isotope production via stellar flares. We find that as a consequence of their small convective envelope mass near the turn-off point, low-metallicity dwarfs and subgiants may possess observable amounts of $^6$Li arising from

A. Vecchio, M. Colpi, A. Polnarev

We investigate the evolution of a massive black hole pair under the action of dynamical friction (DF) by a uniform background of light stars with isotropic velocity distribution. In our scenario, the primary black hole $M_1$ sits, at rest, in the center of the spherical star distribution (with mass $M_c$) and the secondary less massive companion $M_2$ moves

Mikel Susperregi, James Binney

A scheme is developed which enables one to trace backwards in time the cosmic density and velocity fields, and to determine accurately the current-epoch velocity field from the current-epoch density field, or vice versa. The scheme implements the idea of Giavalisco \etal\ (1993) that the principle of least action should be used to formulate gravitational ins

Yves Laszlo

We analyze the local structure of the moduli space of semi-stable bundles on a curve. In particular, a complete description of the local structure is given in the rank 2 case. We obtain as a corollary of this analysis new results about the Kummer variety and the Coble quartic associated to a canonical genus 3 curve.

Tatsuhiko Koike, Masayuki Tanimoto, Akio Hosoya

A thorough classification of the topologies of compact homogeneous universes is given except for the hyperbolic spaces, and their global degrees of freedom are completely worked out. To obtain compact universes, spatial points are identified by discrete subgroups of the isometry group of the generalized Thurston geometries, which are related to the Bianchi a

James M. Cline

Baryogenesis at the electroweak phase transition may take place through CP-violating reflections of quarks from expanding bubbles of the broken symmetry phase. We formulate and approximately solve the transport equations for the reflected quark asymmetries. The results are comparable to a previous Monte Carlo calculation and allow for analytic estimates of t

G. L. Kane, Chris Kolda, Leszek Roszkowski, James D. Wells

In constrained minimal supersymmetry the lightest neutralino of bino-type is the only neutral candidate for dark matter. As a result, one is typically able to restrict all the supersymmetric mass spectra below roughly 1-2\tev\ {\em without} imposing an ill-defined fine-tuning constraint.

Andrew M. Abrahams, Gregory B. Cook

We consider general relativistic Cauchy data representing two nonspinning, equal-mass black holes boosted toward each other. When the black holes are close enough to each other and their momentum is sufficiently high, an encompassing apparent horizon is present so the system can be viewed as a single, perturbed black hole. We employ gauge-invariant perturbat

M. Baillargeon, G. Belanger, F. Boudjema

The main attractions of studying the bosonic sector of the electroweak standard model and its extensions at a future high energy photon collider are reviewed. A presentation of the laser scheme for obtaining such a collider is given where we emphasize the importance of polarised \gag spectra. The need for {\em measuring} the differential luminosities is stre

Suresh Govindarajan, T. Jayaraman

We relate the Teichmuller spaces obtained by Hitchin to the Teichmuller spaces of $WA_{n}$-gravity. The relationship of this space to $W$-gravity is obtained by identifying the flat $PSL(n+1,{\BR})$ connections of Hitchin to generalised vielbeins and connections. This is explicitly demonstrated for $WA_2=W_3$ gravity. We show how $W$-diffeomorphisms are obta

Calvin W. Johnson, Joseph N. Ginocchio

Starting from a general, microscopic fermion-to-boson mapping that preserves Hermitian conjugation, we discuss truncations of the boson Fock space basis. We give conditions under which the exact boson images of finite fermion operators are also finite (e.g., a 1+2-body fermion Hamiltonian is mapped to a 1+2-body boson Hamiltonian) in the truncated basis. For

J. Nemchik, N. N. Nikolaev, B. G. Zakharov

We predict a strikingly different $A$ and $Q^{2}$ dependence of quasielastic leptoproduction of the $ρ^{0}(1S)$-meson and its radial excitation $ρ&#39;(2S)$ on nuclei. Whereas for the $ρ^{0}$ production nuclear transparency $T_{A}$ decreases monotonically with $A$, for the $ρ&#39;$ nuclear transparency $T_{A}$ can have the counterintuitive nonmonotonic $A$-d

Andreas Blass, Rüdiger Göbel

The Baer-Specker group is the product of countably many copies of the additive group Z of integers. Assuming the continuum hypothesis, we construct a pure subgroup G of the Baer-Specker group with the following properties. Every endomorphism of G differs from a scalar multiplication by an endomorphism of finite rank. Yet G has uncountably many homomorphisms

E. Marinari, G. Parisi, F. Ritort

We study systems without quenched disorder with a complex landscape, and we use replica symmetry theory to describe them. We discuss the Golay-Bernasconi-Derrida approximation of the low autocorrelation model, and we reconstruct it by using replica calculations. Then we consider the full model, its low $T$ properties (with the help of number theory) and a Ha

A. A. Andrianov, R. Soldati

We consider the abelian vector-field models in the presence of the Wess-Zumino interaction with the pseudoscalar matter. The occurence of the dynamic breaking of Lorentz symmetry at classical and one-loop level is described for massless and massive vector fields. This phenomenon appears to be the non-perturbative counterpart of the perturbative renormalizabi

Hiroyuki Hata, Yusuke Taniguchi

We present a toy model study of the high temperature deconfining transition in Yang-Mills theory as a breakdown of the confinement condition proposed by Kugo and Ojima. Our toy model is a kind of topological field theory obtained from the Yang-Mills theory by taking the limit of vanishing gauge coupling constant $g_{\rm YM}\to 0$, and therefore the gauge fie

G. L. Kane, Chris Kolda, Leszek Roszkowski, James D. Wells

In the constrained MSSM one is typically able to restrict the supersymmetric mass spectra below roughly 1-2\tev\ {\em without} resorting to the ambiguous fine-tuning constraint.

Palash B Pal

The precise statement of the equivalence theorem, between the longitudinally polarized states of a massive gauge boson and the corresponding goldstone mode, is discussed when the amplitude in question depends on masses of other particles (e.g., the Higgs boson) in the theory.

Xuemin Jin, Thomas D. Cohen

Relations connecting various zero momentum correlators of interpolating fields for pseudoscalar and scalar channel, containing one heavy and one light quark field, are derived from the Euclidean space formulation of the QCD functional integral. These relations may serve as constraints on the phenomenological models or approaches motivated from QCD, and sugge

J. G. Korner, D. Pirjol

Model-independent bounds are presented for the form-factors describing the semileptonic decay $Λ_b\toΛ_ce\barν_e$ at the end-point of the lepton energy spectrum. For the axial-vector form-factor $f_1^A(1)$ we obtain $f_1^A(1)\leq 0.960÷0.935$, where the uncertainty arises from the value of $μ_π^2$, the average kinetic energy of the $b$ quark inside of the $Λ

R. N. Mohapatra

There are strong indications for neutrino masses and mixings in the data on solar neutrinos, the observed deficit of the muon neutrinos from the atmosphere as well as the discussions of the dark matter of the universe after COBE data. It is argued that the SO(10) grand unified has the right symmetry breaking properties as dictated by LEP data to accomodate t

Alon E. Faraggi

I discuss the construction of realistic superstring standard--like models in the four dimensional free fermionic formulation. I discuss the massless spectrum of the superstring standard--like models and the texture of fermion mass matrices. These models suggest an explanation for the top quark mass hierarchy. At the cubic level of the superpotential only the

Nick Evans

We review the recent discussion in the literature of one family extended technicolour models with techni-fermion mass spectra compatible with the experimental data for the precision parameters S,T,U,V, W and X and ETC interactions compatible with the LEP measurements of the $Z\to b{\bar b}$ vertex. To investigate whether these scenarios are consistent with t

J. Nemchik, N. N. Nikolaev, B. G. Zakharov

Elastic production of vector mesons $γ^{*} N\to V N$ is the pomeron-exchange dominated diffractive reaction with much potential of probing the BFKL pomeron. The BFKL pomeron can conveniently be described in terms of the dipole cross section which is a solution of the generalized BFKL equation. In this paper we discuss, how the energy and $Q^{2}$ dependence o

Gye T. Park, T. K. Kuo

We extend our previous work on the precision electroweak tests in the Sp(6)_L X U(1)_Y family model to include for the first time the important Z->b b-bar vertex corrections encoded in a new variable epsilon_b, utilizing all the latest LEP data. We include in our analysis the one loop EW radiative corrections due to the new bosons in terms of epsilon_1, epsi

Thomas Mannel

The recent theoretical progress in the description of semileptonic decays in the framework of the heavy mass expansion is summarized. Both inclusive and exclusive decays are considered.

Fred Cooper, Salman Habib, Yuval Kluger, Emil Mottola

An effective action technique for the time evolution of a closed system consisting of one or more mean fields interacting with their quantum fluctuations is presented. By marrying large $N$ expansion methods to the Schwinger-Keldysh closed time path (CTP) formulation of the quantum effective action, causality of the resulting equations of motion is ensured a

J. E. Avron, R. Seiler, P. Zograf

Quillen&#39;s local index theorem is used to study the charge transport coefficients (adiabatic curvature) associated to the ground state of a Schrödinger operator for a charged (spinless) particle on a closed, multiply connected surface. The formula splits the adiabatic curvature into an explicit integral part and a fluctuating part which has a natural inte

George E. A. Matsas

We revisit the long standing problem of analyzing an inertial electric charge from the point of view of uniformly accelerated observers in the context of semi-classical gravity. We choose a suitable set of accelerated observers with respect to which there is no photon emission coming from the inertial charge. We discuss this result against previous claims [F

I. H. Dwivedi, P. S. Joshi

Generalizing earlier results of Joshi and Dwivedi (Commun. Math. Phys. 146, 333 (1992); Lett. Math. Phys. 27, 235 (1993)), we analyze here the spherically symmetric gravitational collapse of a matter cloud with a general form of matter for the formation of a naked singularity. It is shown that this is related basically to the choice of initial data to the Ei

C. Mudry, E. Fradkin

We reconsider the problem of separation of spin and charge in one dimensional quantum antiferromagnets. We show that spin and charge separation in one dimensional strongly correlated systems cannot be described by the slave boson or fermion representation within any perturbative treatment of the interactions between the slave holons and slave spinons. The co

Z. N. C. Ha

One-dimensional model of non-relativistic particles with inverse-square interaction potential known as Calogero-Sutherland Model (CSM) is shown to possess fractional statistics. Using the theory of Jack symmetric polynomial the exact dynamical density-density correlation function and the one-particle Green&#39;s function (hole propagator) at any rational int

D. M. Whittaker

A new, exact method for calculating excitonic absorption in superlattices is described. It is used to obtain high resolution spectra showing the saddle point exciton feature near the top of the miniband. The evolution of this feature is followed through a series of structures with increasing miniband width. The Stark ladder of peaks produced by an axial elec

B. L. Altshuler, L. S. Levitov, A. Yu. Yakovets

Current fluctuations are studied in a mesoscopic conductor using non-equilibrium Keldysh technique. We derive a general expression for the fluctuations in the presence of a time dependent voltage, valid for arbitrary relation between voltage and temperature. Two limits are then treated: a pulse of voltage and a DC voltage. A pulse of voltage causes phase sen

Viacheslav V. Nikulin

In our preprint: &#34;Algebraic surfaces with log-terminal singularities and nef anticanonical class and reflection groups in Lobachevsky spaces&#34;, Preprint Max-Planck-Institut für Mathematik, Bonn, (1989) MPI/89-28 (Russian), we had extended the diagram method to algebraic surfaces with nef anticanonical class (before, it was applied to Del Pezzo surface

C. O. Lousto

We study the occurrence of critical phenomena in four - dimensional, rotating and charged black holes, derive the critical exponents and show that they fulfill the scaling laws. Correlation functions critical exponents and Renormalization Group considerations assign an effective (spatial) dimension, $d=2$, to the system. The two - dimensional Gaussian approx

Nathan Berkovits, Nobuyoshi Ohta

It was previously shown that at critical central charge, $N$-extended superstrings can be embedded in $(N+1)$-extended superstrings. In other words, $(N=0,c=26)\to (N=1,c=15)\to (N=2,c=6)\to (N=3,c=0) \to (N=4,c=0) $. In this paper, we show that similar embeddings are also possible for $N$-extended superstrings at non-critical central charge. For any $x$, th

Dmitri V. Fursaev

Geometrical form of the one-loop divergences induced by conical singularities of background manifolds is studied. To this aim the heat kernel asymptotic expansion on spaces having the structure $C_α\times Σ$ near singular surface $Σ$ is analysed. Surface corrections to standard second and third heat coefficients are obtained explicitly in terms of angle $α$

A. Hamid Bougourzi, Luc Vinet

We review the classical boson-fermion correspondence in the context of the $\widehat{sl(2)}$ current algebra at level 2. This particular algebra is ideal to exhibit this correspondence because it can be realized either in terms of three real bosonic fields or in terms of one real and one complex fermionic fields. We also derive a fermionic realization of the

Bin Shao, R. D. Amado

We model the $N\bar{N}$ system at rest as a baryon number zero lump in the Skyrme model including the $ω$ field. We integrate the classical equations of motion from the highly non-perturbative annihilation region into the non-interacting radiation zone. Subsequent coherent state quantization of the radiation field gives a good description of the pion spectru

R. De Pietri, L. Lusanna, M. Pauri

In a preceding paper we developed a reformulation of Newtonian gravitation as a {\it gauge} theory of the extended Galilei group. In the present one we derive two true generalizations of Newton&#39;s theory (a {\it ten-fields} and an {\it eleven-fields} theory), in terms of an explicit Lagrangian realization of the {\it absolute time} dynamics of a Riemannia

R. De Pietri, L. Lusanna, M. Pauri

Newton&#39;s standard theory of gravitation is reformulated as a {\it gauge} theory of the {\it extended} Galilei Group. The Action principle is obtained by matching the {\it gauge} technique and a suitable limiting procedure from the ADM-De Witt action of general relativity coupled to a relativistic mass-point.

A. P. Balachandran, L. Chandar, B. Sathiapalan

The edge states of a sample displaying the quantum Hall effect (QHE) can be described by a 1+1 dimensional (conformal) field theory of $d$ massless scalar fields taking values on a $d$-dimensional torus. It is known from the work of Naculich, Frohlich et al.\@ and others that the requirement of chirality of currents in this \underline{scalar} field theory im

Anthony J. Bracken, Gustav W. Delius, Mark D. Gould, Yao-Zhong Zhang

We present a systematic technique to construct solutions to the Yang-Baxter equation which depend not only on a spectral parameter but in addition on further continuous parameters. These extra parameters enter the Yang-Baxter equation in a similar way to the spectral parameter but in a non-additive form. We exploit the fact that quantum non-compact algebras

Moshe Gai, Carlos Bertulani

The E2 cross section calculated by Langanke and Shoppa for the Riken experiment on the Coulomb Dissociation of 8B uses E2 nuclear matrix elements from one specific model. Other nuclear models predict a considerably smaller E2 cross section (by a pproximately a factor of 3 to 4), and Langanke and Shoppa appear to assume the most optimistic scenario predicting

Erik Aurell, Per Salomonson

We investigate the functional determinant of the laplacian on piece-wise flat two-dimensional surfaces, with conical singularities in the interior and/or corners on the boundary. Our results extend earlier investigations of the determinants on smooth surfaces with smooth boundaries. The differences to the smooth case are: a) different ``interaction energies&

E. Celeghini, M. Rasetti, G. Vitiello

Second quantization is revisited and creation and annihilation operators areshown to be related, on the same footing both to the algebra h(1), and to the superalgebra osp(1|2) that are shown to be both compatible with Bose and Fermi statistics. The two algebras are completely equivalent in the one-mode sector but, because of grading of osp(1|2), differ in th

H. J. de Vega

We derive the effective equations for the out of equilibrium time evolution of the order parameter and the fluctuations of a scalar field theory in spatially flat FRW cosmologies. After setting the problem in general we propose a non-perturbative, self-consistent Hartree approximation. The method consists of evolving an initial functional thermal density mat

C. P. Burgess, A. Pilaftsis

We examine the contributions of Majorana neutrinos to CP-violating WWZ and ZZZ self-couplings, using a model in which sterile neutrinos couple to the W and Z by mixing with a fourth-generation heavy lepton. We find that the induced form factors can be as large as 0.5%. The model satisfies all phenomenological bounds in a natural way, including those due to t

Tzu Chiang Yuan

We calculate the leading order QCD fragmentation functions for the production of $P$-wave charmed beauty mesons. Long-distance effects are factored into two nonperturbative parameters: the derivative of the radial wavefunction at the origin and a second parameter related to the probability for a $(\bar b c)$ heavy quark pair that is produced in a color-octet

Ian G. Moss

Some indication of conditions that are necessary for the formation of black holes from the collision of bubbles during a supercooled phase transition in the the early universe are explored. Two colliding bubbles can never form a black hole. Three colliding bubbles can refocus the energy in their walls to the extent that it becomes infinite.

Ian G. Moss, Stephen J. Poletti

The anomalous rescaling for antisymmetric tensor fields, including gauge bosons, and Dirac fermions on Einstein spaces with boundary has been prone to errors and these are corrected here. The explicit calculations lead to some interesting identities that indicate a deeper underlying structure.

M. V. Feigelman, L. B. Ioffe

We study a highly disordered network of superconducting granules linked by weak Josephson junctions in magnetic field and develop a mean field theory for this problem. The diamagnetic response to a slow {\it variations} of magnetic field is found to be analogous to the response of a type-II superconductor with extremely strong pinning. We calculate an effect

Matthias H. Hettler, Johann Kroha, Selman Hershfield

Using the integral equations of the Noncrossing Approximation, the differential conductance is computed as a function of voltage for scattering from a two channel Kondo impurity in a point contact. The results compare well to experimental data on Cu point contacts by Ralph and Buhrman. They support a recently proposed scaling hypothesis, and also show finite

Adam F. Falk, Mark B. Wise, Isard Dunietz

We reconsider the conflict between recent calculations of the semileptonic branching ratio of the $B$ meson and the experimentally measured rate. Such calculations depend crucially on the application of ``local duality'' in nonleptonic decays, and we discuss the relation of this assumption to the weaker assumptions required to compute the semileptonic decay

Jonathan Bagger, Erich Poppitz, Lisa Randall

All generic, calculable models of dynamical supersymmetry breaking have a spontaneously broken $R$ symmetry and therefore contain an $R$ axion. We show that the axion is massive in any model in which the cosmological constant is fine-tuned to zero through an explicit $R$-symmetry-breaking constant. In visible-sector models, the axion mass is in the 100 MeV r

W. de Boer, R. Ehret, D. I. Kazakov

The MSSM distinguishes itself from other GUT&#39;s by a successful prediction of many unrelated phenomena with a minimum number of parameters. Among them: a) Unification of the couplings constants; b)Unification of the masses; c) Proton decay; d) Electroweak symmetry breaking. A combined fit of the free parameters in the MSSM to these low energy constraints

Claudio Coriano`, Rajesh Parwani

We present the three loop contribution (order $e^4$) to the pressure of massless quantum electrodynamics at nonzero temperature. The calculation is performed within the imaginary time formalism. Dimensional regularization is used to handle the usual, intermediate stage, ultraviolet and infrared singularities, and also to prevent overcounting of diagrams duri

A. Georges, A. Sengupta

We solve the two-impurity two-channel Kondo model using a combination of conformal invariance and bosonisation techniques. The odd-even symmetric case is analysed in detail. The RKKY interaction turns out to be exactly marginal, resulting in a line of non-Fermi liquid fixed points. Explicit formulae are given for the critical exponents and for the finite-siz

Mark Wexler

The matrix model of random surfaces with c = inf. has recently been solved and found to be identical to a random surface coupled to a q-states Potts model with q = inf. The mean field-like solution exhibits a novel type of tree structure. The natural question is, down to which--if any--finite values of c and q does this behavior persist? In this work we deve

Murray A. Moinester

This report describes the transitions pion -> meson_1 + meson_2 and also pion -> multi-pion for high energy pions interacting with target nuclei (Z,A). The physics interests are: A) Nuclear inelastic coherent diffraction cross sections for pions, for studies of size fluctuations in the pion wave function. B) Radiative widths of excited meson states, for test

R. Urech

In the framework of chiral perturbation theory virtual photons are included. We calculate the divergences of the generating functional to one loop and determine the structure of the local action that incorporates the counterterms which cancel the divergences. As an application we discuss the corrections to Dashen&#39;s theorem at order [e^2*m(quark)].

Ludwik Dabrowski, Preeti Parashar

Reduction of the left regular representation of quantum algebra $sl_q(3)$ is studied and ~$q$-difference intertwining operators are constructed. The irreducible representations correspond to the spaces of local sections of certain line bundles over the q-flag manifold.

Nobuhiko Taniguchi, A. V. Andreev, Boris L. Altshuler

The statistical description of oscillator strengths for systems like hydrogen in a magnetic field is developed by using the supermatrix nonlinear $σ$-model. The correlator of oscillator strengths is found to have a universal parametric and frequency dependence, and its analytical expression is given. This universal expression applies to quantum chaotic syste

Volker Koch

The E814-collaboration has found a component of very low $m_t$ $K^+$ mesons with a slope parameter of $T \sim 15 \, \rm MeV$. We will present a scenario which explains the observed slope parameter and which allows us to predict the expected slope parameter for kaons produced in heavier systems such as Au+Au. Implications for the restoration of chiral symmetr

Doron Zeilberger

How Enumerative Combinatorics met Special Functions, thanks to Joe Gillis

Andreas Blass

Following a remark of Lawvere, we explicitly exhibit a particularly elementary bijection between the set T of finite binary trees and the set T^7 of seven-tuples of such trees. "Particularly elementary" means that the application of the bijection to a seven-tuple of trees involves case distinctions only down to a fixed depth (namely four) in the given seven-

Andreas Blass

We establish a course-of-values induction principle for K-finite sets in intuitionistic type theory. Using this principle, we prove a pigeonhole principle conjectured by Benabou and Loiseau. We also comment on some variants of this pigeonhole principle.

Andreas Blass

We study Baire category for subsets of 2^omega that are downward-closed with respect to the almost-inclusion ordering (on the power set of the natural numbers, identified with 2^omega). We show that it behaves better in this context than for general subsets of 2^omega. In the downward-closed context, the ideal of meager sets is prime and b-complete (where b

Andreas Blass

We classify many cardinal characteristics of the continuum according to the complexity, in the sense of descriptive set theory, of their definitions. The simplest characteristics (boldface Sigma^0_2 and, under suitable restrictions, Pi^0_2) are shown to have pleasant properties, related to Baire category. We construct models of set theory where (unrestricted