April 1999 arXiv papers — page 20

D. H. McIntosh, H. -W. Rix, M. J. Rieke, C. B. Foltz

We have observed a sample of 22 luminous quasars, in the range 2.0<z<2.5, at 1.6 microns with the near-infrared (NIR) spectrograph FSPEC on the Multiple Mirror Telescope. Our sample contains 13 radio-loud and 9 radio-quiet objects. We have measured the systemic redshifts z_(sys) directly from the strong [O III]5007 line emitted from the narrow-line-region. F

Scott J. Kenyon

This paper describes eruptive phenomena in pre-main sequence stars. The eruptions of FU Orionis stars have much in common with outbursts in other accreting systems, such as dwarf novae and some symbiotic stars. These common features are best understood as increases in the rate material flows through an accretion disk. The spectroscopic properties, decay of t

J. I. Katz

I consider radio emission from the remarkable SN1998bw. Ni-56 and Co-56 decays produce a gamma-ray flux whose Compton-scattered electrons naturally explain the observed mildly relativistic exapnsion of the radio source and its double- peaked history. Such models require a surrounding plasma, perhaps produced by the supernova progenitor, whose interaction wit

Bo-yu Hou, Wen-Li Yang, Yao-Zhong Zhang

We derive the exchange relations of the vertex operators of $U_q(A_2^{(2)})$ and show that these vertex operators give the bosonization of the Izergin-Korepin model. We give an integral expression of the correlation functions of the Izergin-Korepin model and derive the difference equations which they satisfy.

Wen-Li Yang, Yao-Zhong Zhang

We derive from the super RS algebra the Drinfeld basis of the twisted quantum affine superalgebra $U_q[osp(2|2)^{(2)}]$ by means of the Gauss decomposition technique. We explicitly construct a nonclassical level-one representation of $U_q[osp(2|2)^{(2)}]$ in terms of two $q$-deformed free boson fields.

Jung-Hoon Kim, Hai-Woong Lee

Canonical transformations using the idea of quantum generating functions are applied to construct a quantum Hamilton-Jacobi theory, based on the analogy with the classical case. An operator and a c-number forms of the time-dependent quantum Hamilton-Jacobi equation are derived and used to find dynamical solutions of quantum problems. The phase-space picture

Feng Luo

This goal of the paper is to show that the automorphisms of the complex of curves in a surface are induced by the self-homeomorphisms of the surface except the surface is the 2-holed torus.

Feng Luo

This paper attempts to relate some ideas of Grothendieck in his Esquisse d&#39;un programme and some of the recent results on 2-dimensional topology and geometry. Especially, we shall discuss the Teichmüller theory, the mapping class groups, $SL(2, \bold C)$ representation variety of surface groups, and Thurston&#39;s theory of measured laminations.

Mark D. Roberts

Solutions to gravity with quadratic Lagrangians are found for the simple case where the only nonconstant metric component is the lapse $N$ and the Riemann tensor takes the form $R^{t}_{.itj}=-k_{i}k_{j}, i,j=1,2,3$; thus these solutions depend on cross terms in the Riemann tensor and therefore complement the linearized theory where it is the derivatives of t

Mark D. Roberts

The field equations of general relativity can be written as first order differential equations in the Weyl tensor, the Weyl tensor in turn can be written as a first order differential equation in a three index tensor called the Lanczos tensor. The Lanczos tensor plays a similar role in general relativity to that of the vector potential in electro-magnetic th

V. B. Priezzhev

The existing estimation of the upper critical dimension of the Abelian Sandpile Model is based on a qualitative consideration of avalanches as self-avoiding branching processes. We find an exact representation of an avalanche as a sequence of spanning sub-trees of two-component spanning trees. Using equivalence between chemical paths on the spanning tree and

Zhou Haijun, Zhang Yang, Ou-Yang Zhong-can

A unified model is constructed to study the recently observed DNA entropic elasticity, cooperative extensibility, and supercoiling property. With the introduction of a new structural parameter (the folding angle $ϕ$), bending deformations of sugar-phosphate backbones, steric effects of nucleotide basepairs, and short-range basestacking interactions are consi

Xiao-Gang Wen

We find that, under certain condition, a quantum dot with odd number of electron and coupled to two leads can be described by a non-equilibrium 2-channel Kondo model, when the two leads has a large voltage bias between them. The model is exactly soluble and can be mapped into a free fermion system, even in the presence of external magnetic field and other re

E. Bergshoeff, P. K. Townsend

Energy bounds are derived for planar and compactified M2-branes in a hyper-K\"ahler background. These bounds are saturated, respectively, by lump and Q-kink solitons, which are shown to preserve a half of the worldvolume supersymmetry. The Q-kinks have a dual IIB interpretation as strings that migrate between fivebranes.

Barry M. McCoy

In the past 30 years there have been extensive discoveries in the theory of integrable statistical mechanical models including the discovery of non-linear differential equations for Ising model correlation functions, the theory of random impurities, level crossing transitions in the chiral Potts model and the use of Rogers-Ramanujan identities to generalize

Leonid L. Frankfurt, Gerald A. Miller, Misak M. Sargsian, Mark I. Strikman

Photon absorption by a quark in one nucleon followed by its high momentum transfer interaction with a quark in the other may produce two final-state nucleons with high relative momentum. We sum the relevant quark rescattering diagrams, to show that the scattering amplitude depends on a convolution between the large angle $pn$ scattering amplitude, the hard p

D. Z. Freedman, S. S. Gubser, K. Pilch, N. P. Warner

We obtain first order equations that determine a supersymmetric kink solution in five-dimensional N=8 gauged supergravity. The kink interpolates between an exterior anti-de Sitter region with maximal supersymmetry and an interior anti-de Sitter region with one quarter of the maximal supersymmetry. One eighth of supersymmetry is preserved by the kink as a who

Su Houng Lee

We will summarize the progress in understanding the changes in the vector meson spectral density in nuclear medium using the constraint equations obtained from the Borel transformed dispersion relation and QCD Operator Product Expansion. We will discuss the results for the scalar mass shift and dispersion effects (three momentum dependence) for the light qua

Veit Elser

The level set of an elliptic function is a doubly periodic point set in C. To obtain a wider spectrum of point sets, we consider, more generally, a Riemann surface S immersed in C^2 and its sections (``cuts&#39;&#39;) by C. We give S a crystallographic isometry in C^2 by defining a fundamental surface element as a conformal map of triangular domains and S as

D. I. Panyushev

Recently, V.Ginzburg introduced the notion of a principal nilpotent pair (= pn-pair) in a semisimple Lie algebra {\frak g}. It is a double counterpart of the notion of a regular nilpotent element. A pair (e_1,e_2) of commuting nilpotent elements is called a pn-pair, if the dimension of their simultaneous centralizer is equal to the rank of {\frak g} and some

Tao Jiang, Dhruv Mubayi, Aditya Shastri, Douglas B. West

The edge-bandwidth of a graph is the minimum, over all labelings of the edges with distinct integers, of the maximum difference between labels of two incident edges. We prove that edge-bandwidth is at least as large as bandwidth for every graph, with equality for certain caterpillars. We obtain sharp or nearly-sharp bounds on the change in edge-bandwidth und

Daniel Matei, Alexander I. Suciu

For an arrangement with complement X and fundamental group G, we relate the truncated cohomology ring, H^{<=2}(X), to the second nilpotent quotient, G/G_3. We define invariants of G/G_3 by counting normal subgroups of a fixed prime index p, according to their abelianization. We show how to compute this distribution from the resonance varieties of the Orlik-S

G. Dvali, M. Shifman

We discuss theories in which the standard-model particles are localized on a brane embedded in space-time with large compact extra dimensions, whereas gravity propagates in the bulk. In addition to the ground state corresponding to a straight infinite brane, such theories admit a (one parameter) family of stable configurations corresponding to branes wrappin

Tadahiko Kimura, Ichiro Oda

We examine duality transformations of supersymmetric and $κ$-symmetric Dp-brane actions in a general type II supergravity background where in particular the dilaton and the axion are supposed to not be zero or a constant but a general superfield. Due to non-constant dilaton and axion, we can explicitly show that the dilaton and the axion as well as the two 2

H. Itoyama, A. Tsuchiya

We review the construction and theoretical implications of the USp(2k) matrix model in zero dimension introduced in ref. \cite{IT1,IT2}. It is argued that the model provides a constructive approach to Type I superstrings and is at the same time dynamical theory of spacetime points. Three subjects are discussed : semiclassical pictures and series of degenerat

Dao-Neng Gao, Mu-Lin Yan

A systematic method developed by the authors to evaluate the one-loop electromagnetic self-energies of the low-lying mesons is extended to the calculation of the vector sector including $ρ$, $ω$, and $ϕ$-mesons. The theoretical result of $ρ^0-ρ^\pm$ electromagnetic mass difference is in agreement with the measurements. An interesting effect called as electro

Yoshinobu Kuramashi

We present a summary of our results for the light hadron spectrum in quenched lattice QCD and preliminary ones in two-flavor full QCD. For the quenched hadron spectrum we find that the mass formulae predicted by quenched chiral perturbation theory(QChPT) give a good description of our results. Employing the QChPT mass formulae for chiral extrapolations we co

Y. Meurice, S. Niermann

Using a simplified version of the RG transformation of Dyson&#39;s hierarchical model, we show that one can calculate all the non-universal quantities entering into the scaling laws by combining an expansion about the high-temperature fixed point with a dual expansion about the critical point. The magnetic susceptibility is expressed in terms of two dual qua

Y. Ishikawa, H. Fukuyama

The spatial distribution of electric current under magnetic field and the resultant orbital magnetism have been studied for two-dimensional electrons under a harmonic confining potential $V(\vecvar{r})=m ω_0^2 r^2/2$ in various regimes of temperature and magnetic field, and the microscopic conditions for the validity of Landau diamagnetism are clarified. Und

J. G. E. Harris, J. E. Grimaldi, D. D. Awschalom, A. Chiolero

Temperature-dependent magnetization measurements on a series of synthetic ferritin proteins containing from 100 to 3000 Fe(III) ions are used to determine the uncompensated moment of these antiferromagnetic particles. The results are compared with recent theories of macroscopic quantum coherence which explicitly include the effect of this excess moment. The

Y. D. Chuang, A. D. Gromko, D. S. Dessau, Y. Aiura

We present a re-examination of the electronic structure and Fermi Surface (FS) of Bi-Sr-Ca-Cu-O (BSCCO) as obtained from angle-resolved photoemission experiments. By applying a stricter set of FS crossing criteria as well as by varying the incident photon energy outside the usual range, we have found very different behavior from that previously observed. In

Kevork Abazajian, Xiangdong Shi, George M. Fuller

We investigate the effects of matter-enhanced (MSW) transformation of neutrinos in the Early Universe on the primordial helium yield (Y_p). We find that Y_p is affected much more by the MSW-induced alterations in the neutrino energy spectra than by the associated change in expansion rate. Specifically, the absence due to transformation of low energy electron

Michael S. Turner

The discussion of cosmological parameters used to be a source of embarrassment to cosmologists. Today, measurements of the cosmological parameters are leading the way into the era of precision cosmology. The CMB temperature is measured to four significant figures, T_0=2.7277+/-0.002 K; the Hubble constant is now determined with a reliable error estimate, H_0

Vera C. Rubin, Andrew H. Waterman, Jeffrey D. P. Kenney

For 89 galaxies, mostly spirals, in the Virgo cluster region, we have obtained optical long-slit major axis spectra of the ionized gas. We find: (1) One-half of the Virgo galaxies we observed have regular rotation patterns, while the other 50% exhibit kinematic disturbances ranging from mild to major. Velocity complexities are generally consistent with those

Michael S. Turner

Theoretical cosmologists were quick to be convinced by the evidence presented in 1998 for the accelerating Universe. I explain how this remarkable discovery was the missing piece in the grand cosmological puzzle. When found, it fit perfectly. For cosmologists, this added extra weight to the strong evidence of the SN Ia measurements themselves, making the res

Steven N. Shore, T. N. LaRosa

We propose a model for the origin of the isolated nonthermal filaments observed at the Galactic center based on an analogy to cometary plasma tails. We invoke the interaction between a large scale magnetized galactic wind and embedded molecular clouds. As the advected wind magnetic field encounters a dense molecular cloud, it is impeded and drapes around the

J. Craig Wheeler, Peter Hoeflich, Lifan Wang

Study of the polarization of supernovae has suggested that the core collapse process may be intrinsically strongly asymmetric. There is a tentative trend for supernova with smaller envelopes showing more polarization, with Type Ic having the smallest envelopes and showing the largest polarization. The recent discovery of the unusual supernova SN 1998bw and i

Henry E. Kandrup, Christos Siopis, George Contopoulos, Rudolf Dvorak

This paper summarises an investigation of the statistical properties of orbits escaping from three different two-degree-of-freedom Hamiltonian systems which exhibit global stochasticity. Each H=H_{0}+eH&#39;, with H_{0} integrable and eH&#39; a nonintegrable correction, not necessarily small. For e below a critical e_{0} escapes are impossible energetically.

Anatoli Vankov

Super-high energy corpuscular and gamma rays as well as cosmic high--power density sources are hard to explain in a galaxy model framework. Attempts to include some of those phenomena in the Standard Cosmological Model also encounter serious difficulties. In the present paper an alternative cosmological concept is discussed. There are several features in it.

Kenji Bekki

Recent morphological studies of QSO host galaxies by the Hubble Space Telescope (HST) have revealed that a sizable fraction of QSO host galaxies possess close small companion galaxies. It is however not clear why and how these companion galaxies are physically associated with the activation of QSO nucleus and the formation of QSO hosts. We here demonstrate t

Robin Ciardullo, Howard E. Bond, Michael S. Sipior, Laura K. Fullton

We report results of an HST &#34;snapshot&#34; survey aimed at finding resolved binary companions of the central stars of Galactic planetary nebulae (PNe). Using WF/PC and WFPC2, we searched the fields of 113 PNe for stars whose close proximity to the central star suggests a physical association. We find 10 binary nuclei that are very likely to be physically

Tomonori Totani

Galaxies exhibit a sequence of various morphological types, i.e., the Hubble sequence, and they are basically composed of spheroidal components (elliptical galaxies and bulges in spiral galaxies) and disks. It is known that spheroidal components are found only in relatively massive galaxies with M=10^{10-12} M_sun, and all stellar populations in them are ver

Xiangdong Shi, George M. Fuller

We extend a treatment of the causal structure of space-time to active-sterile neutrino transformation-based schemes for lepton number generation in the early universe. We find that these causality considerations necessarily lead to the creation of spatial domains of lepton number with opposite signs. Lepton number gradients at the domain boundaries can open

P. Meszaros

Major advances have been made in the field of gamma-ray bursts in the last two years. The successful discovery of X-ray, optical and radio afterglows, which were predicted by theory, has made possible the identification of host galaxies at cosmological distances. The energy release inferred in these outbursts place them among the most energetic and violent e

Gia Dvali, Gregory Gabadadze

We argue that global charges, such as baryon or lepton number, are not conserved in theories with the Standard Model fields localized on the brane which propagates in higher-dimensional space-time. The global-charge non-conservation is due to quantum fluctuations of the brane surface. These fluctuations create &#34;baby branes&#34; that can capture some glob

Deborah B. Haarsma, R. Bruce Partridge, Ian Waddington, Rogier A. Windhorst

Faint extragalactic radio sources provide important information about the global history of star formation. Sensitive radio observations of the Hubble Deep Field and other fields have found that sub-mJy radio sources are predominantly associated with star formation activity rather than AGN. Radio observations of star forming galaxies have the advantage of be

C. Balazs, D. A. Dicus, H. -J. He, W. W. Repko

We present collider tests of the recent proposal for weak-scale quantum gravity due to new large compact space dimensions in which only the graviton ($\G$) propagates. We show that the existing high precision LEP-I $Z$-pole data can impose non-trivial constraints on the scale of the new dimensions, via the decay mode $Z\to f\bar{f}+\G$ ($f=q,\ell$). These bo

Yi Ling, Lee Smolin

We define supersymmetric spin networks, which provide a complete set of gauge invariant states for supergravity and supersymmetric gauge theories. The particular case of Osp(1/2) is studied in detail and applied to the non-perturbative quantization of supergravity. The supersymmetric extension of the area operator is defined and partly diagonalized. The spec

M. R. Norman

A defining property of metals is the existence of a Fermi surface: for two dimensions, a continuous contour in momentum space which separates occupied from unoccupied states. In this paper, I discuss angle resolved photoemission data on the cuprate superconductor BSCCO and argue that it is not best thought of in this conventional picture. Rather, the data ar

Andreas Wacker, Ben Yu-Kuang Hu

We derive a theory for transmission through disordered finite superlattices in which the interface roughness scattering is treated by disorder averaging. This procedure permits efficient calculation of the transmission thr ough samples with large cross-sections. These calculations can be performed utilizing either the Keldysh or the Landauer-Büttiker transmi

Paolo Zanardi, Mario Rasetti

We show that the notion of generalized Berry phase i.e., non-abelian holonomy, can be used for enabling quantum computation. The computational space is realized by a $n$-fold degenerate eigenspace of a family of Hamiltonians parametrized by a manifold $\cal M$. The point of $\cal M$ represents classical configuration of control fields and, for multi-partite

W. Buchmuller, D. Delepine, F. Vissani

We study the implications of a large $ν_μ- ν_τ$ mixing angle on lepton flavour violating radiative transitions in supersymmetric extensions of the standard model. The transition rates are calculated to leading order in $ε$, the parameter which characterizes the flavour mixing. The uncertainty of the predicted rates is discussed in detail. For models with mod

D. Teaney, E. V. Shuryak

The space-time evolution of high energy non-central heavy ion collisions is studied with relativistic hydrodynamics. The results are very sensitive to the Equation of State(EoS). For an EoS with the QCD phase transition, an unusual matter distribution develops. Before freeze-out, two shells are formed which then physically separate and leave a maximum in the

Gabriele Ferretti, Jussi Kalkkinen, Dario Martelli

In this paper we continue the study of the non-critical type 0 string and its field theory duals. We begin by reviewing some facts and conjectures about these theories. We move on to our proposal for the type 0 effective action in any dimension, its RR fields and their Chern--Simons couplings. We then focus on the case without compact dimensions and study it

C. Kergueris, J. -P. Bourgoin, S. Palacin, D. Esteve

Molecules of bisthiolterthiophene have been adsorbed on the two facing gold electrodes of a mechanically controllable break junction in order to form metal-molecule(s)-metal junctions. Current-voltage (I-V) characteristics have been recorded at room temperature. Zero bias conductances were measured in the 10-100 nS range and different kinds of non-linear I-V

Z. G. Dai, T. Lu

Recent observations show that the temporal decay of the R-band afterglow from GRB 990123 steepened about 2.5 days after the burst. We here propose a possible explanation for such a steepening: a shock expanding in a dense medium has undergone the transition from a relativistic phase to a nonrelativistic phase. We find that this model is consistent with the o

P. Lanoix, R. Garnier, G. Paturel, C. Petit

We present in this paper an exhaustive compilation of all published data of extragalactic Cepheids. We have checked every light curve in order to characterize the different types of Cepheid and detect potential overtone pulsators, or to estimate the quality of the data. This compilation of about 3000 photometric measurements will constitute a very useful too

Jesús Salas, Alan D. Sokal

Using results from conformal field theory, we compute several universal amplitude ratios for the two-dimensional Ising model at criticality on a symmetric torus. These include the correlation-length ratio x^\star = \lim_{L\to\infty} ξ(L)/L and the first four magnetization moment ratios V_{2n} = <{\cal M}^{2n}>/<{\cal M}^2>^n. As a corollary we get the first

M. Nishimura, Y. Tanii

Anomalies of N = (4,4) superconformal field theories coupled to a conformal supergravity background in two dimensions are computed by using the AdS/CFT correspondence. We find that Weyl, axial gauge and super Weyl transformations are anomalous, while general coordinate, local Lorentz, vector gauge and local super transformations are not. The coefficients of

Shinji Mukohyama

It is shown that the Hartle-Hawking state of a scalar field is a maximum of entanglement entropy in the space of pure quantum states satisfying the condition that backreaction is finite. In other words, the Hartle-Hawking state is a curved-space analogue of the EPR state, which is also a maximum of entanglement entropy.

Jizhong Lou, Xi Dai, Shaojin Qin, Zhaobin Su

Using the density matrix renormalization group technique, we calculate numerically the low energy excitation spectrum and magnetization curve of the spin-1 antiferromagnetic chain in a staggered magnetic field, which is expected to describe the physics of $R_2 Ba Ni O_5 (R \neq Y) $ family below the Néel temperature of the magnetic rare-earth ($R$) sublattic

W. Ketterle, D. S. Durfee, D. M. Stamper-Kurn

Contribution to the proceedings of the 1998 Enrico Fermi summer school on Bose-Einstein condensation in Varenna, Italy.

Zurab Kakushadze

We consider non-perturbative six and four dimensional N=1 space-time supersymmetric orientifolds. Some states in such compactifications arise in ``twisted&#39;&#39; open string sectors which lack world-sheet description in terms of D-branes. Using Type I-heterotic duality we are able to obtain the massless spectra for some of such orientifolds. The four dime

H. -J. Briegel, T. Calarco, D. Jaksch, J. I. Cirac

We develop a method to entangle neutral atoms using cold controlled collisions. We analyze this method in two particular set-ups: optical lattices and magnetic micro-traps. Both offer the possibility of performing certain multi-particle operations in parallel. Using this fact, we show how to implement efficient quantum error correction and schemes for fault-

Boris F. Samsonov

New types of irreducible second order Darboux transformations for the one dimensional Schroedinger equation are described. The main feature of such transformations is that the transformation functions have the eigenvalues grater then the ground state energy of the initial (or reference) Hamiltonian. When such a transformation is presented as a chain of two f

S. Liberati, Matt Visser, F. Belgiorno, D. W. Sciama

In this talk I shall describe an extension of the quantum-vacuum approach to sonoluminescence proposed several years ago by J.Schwinger. We shall first consider a model calculation based on Bogolubov coefficients relating the QED vacuum in the presence of an expanded bubble to that in the presence of a collapsed bubble. In this way we shall derive an estimat

I. B. Khriplovich, A. I. Milstein

We discuss some paradoxes arising due to the gauge-dependence of canonical variables in mechanics.

Joel M. Williams, George H. Sprenger

The corresponding states principle is an important concept wherein materials are interrelated. The base state of this principle, however, currently has no specific physical reality. Instead, it is a definition: a set of conditions at which the gas state reaches its maximum compression and liquid can not longer form; namely, the critical point. This article s

R. J. M. Snellings, A. M. Poskanzer, S. A. Voloshin

We first review previous work on anisotropic flow at the AGS and SPS. Then the physics related to flow is discussed as well as the interaction of flow with other non-flow measurements. From 40k RQMD and 100k HIJING events predictions for anisotropic flow at RHIC are presented. Using the STAR detector acceptance, estimates for the resolution obtainable with S

Alexei Borodin, Grigori Olshanski

We study a 3-parametric family of stochastic point processes on the one-dimensional lattice originated from a remarkable family of representations of the infinite symmetric group. We prove that the correlation functions of the processes are given by determinantal formulas with a certain kernel. The kernel can be expressed through the Gauss hypergeometric fun

Alexander O. Prishlyak

The complete invariant for gradient like Morse-Smale dynamical systems (vector fields and diffeomorphisms) on closed 4-manifolds are constructed. It is same as Kirby diagram in a case of polar vector field without fixed points of index 3.

Antoine Chambert-Loir, Yuri Tschinkel

We prove asymptotic formulas for the number of rational points of bounded height on certain blow-ups of the projective space.

M. Ram&#39;on Medrano, N. S&#39;anchez

The density of mass levels ρ(m) and the critical temperature for strings in de Sitter space-time are found. QFT and string theory in de Sitter space are compared. A `Dual&#39;-transform is introduced which relates classical to quantum string lengths, and more generally, QFT and string domains. Interestingly, the string temperature in De Sitter space turns ou

Christian Brouder

A connection between the algebra of rooted trees used in renormalization theory and Runge-Kutta methods is pointed out. Butcher&#39;s group and B-series are shown to provide a suitable framework for renormalizing a toy model of field the ory, following Kreimer&#39;s approach. Finally B-series are used to solve a class of non-linear partial differential equat

J. Ambjorn, K. N. Anagnostopoulos, R. Loll

We provide compelling evidence that a previously introduced model of non-perturbative 2d Lorentzian quantum gravity exhibits (two-dimensional) flat-space behaviour when coupled to Ising spins. The evidence comes from both a high-temperature expansion and from Monte Carlo simulations of the combined gravity-matter system. This weak-coupling behaviour lends fu

Mariano Cadoni

We perform the spherical symmetric dimensional reduction $4d\to2d$ of heterotic string theory. We find a class of two-dimensional (2d) dilaton gravity models that gives a general description of the near-horizon, near-extremal behavior of four-dimensional (4d) heterotic string black holes. We show that the duality group of the 4d theory is realized in two dim

Joseph Polchinski, Leonard Susskind

See hep-th/9903228.

Ronald Bryan

Some time ago Rubakov and Shaposhnikov (RS) suggested that elementary particles might be excitations trapped on a soliton in a flat higher dimensional space. They gave as an example phi-4 theory in five dimensions with a bosonic excitation on a domain wall in the fifth dimension. They also trapped a chiral Dirac particle on the domain wall. We extend the RS

M. Czakon, J. Gluza, M. Zralek

In any gauge model with spontaneous symmetry breakdown the gauge boson masses and their mixings are not independent quantities. They are interconnected through the vacuum expectation values (VEVs) of the Higgs sector. We discuss the low-energy experiments, namely electron-hadron, neutrino-hadron and neutrino-electron processes in the frame of the Manifest Le

Debajyoti Choudhury, Jan Kalinowski, Anna Kulesza

We investigate the sensitivity of future linear collider experiments to CP violating $WWγ$ couplings in the process $e^{+}e^{-} \to ν\barνγ$. We consider several sets of machine parameters: centre of mass energies $\sqrt{s}$ = 350, 500 and 800 GeV and operating at different luminosities. From an analysis of the differential cross-section the following 95% C.

I. Caprini, L. Micu, C. Bourrely

Recently, the final state strong interactions in nonleptonic B decays were investigated in a formalism based on hadronic unitarity and dispersion relations in terms of the off-shell mass squared of the $B$ meson. We consider an heuristic derivation of the dispersion relations in the mass variables using the reduction LSZ formalism and find a discrepancy betw

E155 Collaboration

New measurements are reported on the deuteron spin structure function g_1^d. These results were obtained from deep inelastic scattering of 48.3 GeV electrons on polarized deuterons in the kinematic range 0.01 < x < 0.9 and 1 < Q^2 < 40 (GeV/c)^2. These are the first high dose electron scattering data obtained using lithium deuteride (6Li2H) as the target mat

Israel Quiros

A classification of Brans-Dicke theories of gravitation, based on the behaviour of the dimensionless gravitational coupling constant, is given. It is noted that the discussion takes place in the current literature, about which of the two distinguished conformal frames in which scalar-tensor theories of gravity can be formulated: the Jordan frame and the Eins

David I. Santiago, Alexander S. Silbergleit

We study the dynamical description of gravity, the appropriate definition of the scalar field energy-momentum tensor, and the interrelation between them in scalar-tensor theories of gravity. We show that the quantity which one would naively identify as the energy-momentum tensor of the scalar field is not appropriate because it is spoiled by a part of the dy

U. Welp, A. Berger, D. J. Miller, V. K. Vlasko-Vlasov

Magnetic field induced transitions in the antiferromagnetic layered manganite La1.4Sr1.6Mn2O7 were studied using magnetization measurements and a high-resolution magneto-optical imaging technique. We report the first direct observation of the formation of ferromagnetic domains appearing at the first order spin-flop transition. The magnetization process proce

D. N. Argyriou, H. N. Bordallo, J. F. Mitchell, J. D. Jorgensen

Neutron diffraction data presented in this paper demonstrates the relevance of lattice displacement above TC, in our understanding of the evolution of the crystal structure with temperature in the layered CMR manganite La1.2Sr1.8Mn2O7. The anomalous temperature behavior of thermal diffuse scattering (TDS) in La1.2Sr1.8Mn2O7 strongly suggests that it arises f

J. C. Flores

We consider a sequence of idealized measurements of time-separation $Δt$ onto a discrete one-dimensional disordered system. A connection with Markov chains is found. For a rapid sequence of measurements, a diffusive regime occurs and the diffusion coefficient $D$ is analytically calculated. In a general point of view, this result suggests the possibility to

E. Kanzieper

An exact solution to the problem of parametric level statistics in non-Gaussian ensembles of N by N Hermitian random matrices with either soft or strong level confinement is formulated within the framework of the orthogonal polynomial technique. Being applied to random matrices with strong level confinement, the solution obtained leads to emergence of a new

F. C. Alcaraz, R. Z. Bariev

A new family of exactly solvable models is introduced. These models are generalizations of the XXZ chain where the distance among spins up ($σ^z$-basis) cannot be smaller or equal to t (t=0,1,2,...). The case t=0 recovers the standard XXZ chain. The coordinate Bethe ansatz is applied and the phase diagram is calculated. Exploring the finite-size consequences

F. C. Alcaraz, R. Z. Bariev

A new integrable version of the degenerate supersymmetric t-J model is proposed. In this formulation instead of restricting single occupancy of electrons at each lattice site we may have up to two electrons at each site. As a requirement of exact integrability the hopping interaction turns out to be correlated with the density of electrons in the neighboring

F. C. Alcaraz, R. Z. Bariev

The exact solution is obtained for the eigenvalues and eigenvectors of the row-to-row transfer matrix of a two-dimensional vertex model with unlimited number of states per bond. This model is a classical counterpart of a quantum spin chain with an unlimited value of spin. This quantum chain is studied using general predictions of conformal field theory. The

R. Brako, D. Sokcevic

We formulate the theory of the perturbation caused by an adsorbate upon the substrate lattice in terms of a local modification of the interatomic potential energy around the adsorption site, which leads to the relaxation of substrate atoms. We apply the approach to CO chemisorption on close-packed metal surfaces, and show that the adsorbate-adsorbate interac

Chin-Kun Hu, N. Sh. Izmailian

We develop a transfer matrix method to compute exactly the spin-spin correlation functions of Bethe lattice spin models in the external magnetic field h and for any temperature T. We first compute the correlation function for the most general spin - S Ising model, which contains all possible single-ion and nearest-neighbor pair interactions. This general spi

R. Carretero-González, S. Ørstavik, J. Huke, D. S. Broomhead

We compare the behaviour of a small truncated coupled map lattice with random inputs at the boundaries with that of a large deterministic lattice essentially at the thermodynamic limit. We find exponential convergence for the probability density, predictability, power spectrum, and two-point correlation with increasing truncated lattice size. This suggests t

J. J. Brainerd

A plasma instability theory is presented for the prompt radiation from gamma-ray bursts. In the theory, a highly relativistic shell interacts with the interstellar medium through the filamentation and the two-stream instabilities to convert bulk kinetic energy into electron thermal energy and magnetic field energy. The processes are not efficient enough to s

J. J. Brainerd, G. Pendleton, R. Mallozzi, M. S. Briggs

All gamma-ray bursts are observed to have approximately the same characteristic gamma-ray energy. We show in this article that for bursts in the BATSE data set, this property as measured by the E-peak value is not an instrumental effect, but a physical property of gamma-ray bursts.

J. J. Brainerd

A new theory for gamma-ray burst radiation is presented. In this theory, magnetic fields and relativistic electrons are created through plasma processes arising as a relativistic shell passes through the interstellar medium. The gamma-rays are produced through synchrotron self-Compton emission. It is found that shocks do not arise in this theory, and that ef

J. D. Monnier, T. R. Geballe, W. C. Danchi

Recent ground-based mid-infrared spectra of 29 late-type stars, most with substantial dust shells, are compared to ground-based spectra of these stars from the 1960s and 1970s and to IRAS-LRS spectra obtained in 1983. The spectra of about half the stars show no detectable changes, implying that their distributions of circumstellar material and associated dus

E. A. Richards

We describe an observational program aimed at understanding the radio emission from distant, rapidly evolving galaxy populations. These observations were carried out at 1.4 and 8.5 GHz with the VLA centered on the Hubble Deep Field, obtaining limiting flux densities of 40 and 8 $μ$Jy respectively. Using high resolution 1.4 GHz observations obtained with MERL

Philip Plait, Theodore R. Gull

The planetary nebula M94--20 in the Large Magellanic Cloud was serendipitously observed with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope as part of the Hubble Space Telescope Archival Pure Parallel Program. We present spatially resolved imaging and spectral data of the nebula and compare them with ground based data, including