June 2000 arXiv papers — page 23

Mario Castagnino, Roberto Diener, Luis Lara, Gabriel Puccini

The upside-down simple harmonic oscillator system is studied in the contexts of quantum mechanics and classical statistical mechanics. It is shown that in order to study in a simple manner the creation and decay of a physical system by ways of Gamow vectors we must formulate the theory in a time-asymmetric fashion, namely using two different rigged Hilbert s

R. Laiho, S. N. Molotkov, S. S. Nazin

Relativistic quantum field theory imposes additional fundamental restrictions on the distinguishability of quantum states. Because of the unavoidable delocalization of the quantum field states in the Minkowski space-time, the reliable (with unit probability) distinguishability of orthogonal states formally requires infinite time. For the cryptographic protoc

Yu. A. Sivov, Yu. I. Tyurin, V. D. Choruzhii

The luminecsence of ZnSCdS-Cu phosphors of various CdS consentration (0-40%) is under investigation. The luminescence was exited by hydrogen atoms during adsorbtion of thermal energy during adsorbtion and impact recombination-heterogeneous chemiluminenscence(HCL) are discussed. The monotone lowering of the conductivity zone bottom level with respect to the v

Kurt Busch, Nipun Vats, Sajeev John, Barry C. Sanders

The radiation dynamics of a dipole antenna embedded in a Photonic Crystal are modeled by an initially excited harmonic oscillator coupled to a non--Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the Photonic Crystal, i.e., Bloch waves and th

V. K. B. Kota, R. Sahu

There is a newly emerging understanding that in the chaotic domain of isolated finite interacting many particle systems smoothed densities define the statistical description of these systems and these densities follow from embedded (two-body) random matrix ensembles and their various deformations. These ensembles predict that the smoothed form of matrix elem

Jan Snellman

We study two partial orders on $[x_1,...,x_n]$, the free abelian monoid on ${x_1,...,x_n}$. These partial orders, which we call the ``strongly stable'' and the ``stable'' partial order, are defined by the property that their filters are precisely the strongly stable and the stable monoid ideals. These ideals arise in the study of generic init

S. E. Cappell, R. Lee, E. Y. Miller

A perturbative SU(3) Casson invariant $Λ_{SU(3)}(X)$ for integral homology 3-spheres is defined. Besides being fully perturbative, it has nice properties: (1) $4 . Λ_{SU(3)}(X)$ is an integer. (2) It is preseved under orientation change. (3) A connected sum formula holds. Explicit calculations of the invariant for $1/k$ surgery on $(2,q)$ torus knots are mad

E. Munoz Garcia, R. Perez Marco

For a balanced cardcounting system we study the random variable of the true count after a number of cards are removed from the remaining deck and we prove a close formula for its standard deviation. As expected, the formula shows that the standard deviation increases with the number of cards removed. This creates a "standard deviation effect" with a

G. Dal Maso

The calibration method is used to identify some minimizers of the Mumford-Shah functional. The method is then extended to more general free discontinuity problems.

G. Dal Maso, H. Frankowska

We prove the uniqueness of the viscosity solution to the Hamilton-Jacobi equation associated with a Bolza problem of the Calculus of Variations, assuming that the Lagrangian is autonomous, continuous, superlinear, and satisfies the usual convexity hypothesis. Under the same assumptions we prove also the uniqueness, in a class of lower semicontinuous function

G. Dal Maso, H. Frankowska

We investigate the value function of the Bolza problem of the Calculus of Variations $$ V (t,x)=\inf \{\int_{0}^{t} L (y(s),y'(s))ds + ϕ(y(t)) : y \in W^{1,1} (0,t; R^n) ; y(0)=x \}, $$ with a lower semicontinuous Lagrangian $L$ and a final cost $ϕ$, and show that it is locally Lipschitz for $t>0$ whenever $L$ is locally bounded. It also satisfies Hamilt

P. Dall'Aglio, G. Dal Maso

We study some properties of the obstacle reactions associated with the solutions of unilateral obstacle problems with measure data. These results allow us to prove that, under very weak assumptions on the obstacles, the solutions do not depend on the components of the negative parts of the data which are concentrated on sets of capacity zero. The proof is ba

Paolo Dall'Aglio

In this paper we study the continuous dependence with respect to obstacles for obstacle problems with measure data. This is deeply investigated introducing a suitable type of convergence, which gives stability under very general hypotheses. Moreover stability with respect to H^1 and uniform convergent obstacles is proved.

P. Dall'Aglio, C. Leone

We give a definition for Obstacle Problems with measure data and general obstacles. For such problems we prove existence and uniqueness of solutions and consistency with the classical theory of Variational Inequalities. Continuous dependence with respect to data is discussed.

Paolo Dall'Aglio

The behaviour of solutions to fourth order problems is studied through the decomposition into a system of second order ones, which leads to relaxed formulations with the introduction of measure terms. This allows to solve a shape optimization problem for a simply supported thin plate.

Anders Kock

In the context of Synthetic Differential Geometry, we describe the square volume of a ``second-infinitesimal simplex'', in terms of square-distance between its vertices. The square-volume function thus described is symmetric in the vertices. The square-volume gives rise to a characterization of the volume form in the top dimension.

Feng Luo, Richard Stong

We establish a Cauchy type inequality for the geometric intersection number between two 1-dimensional submanifolds in a surface. Some of the basic results in Thurston's theory of measured laminations on surfaces are derived from the Cauchy inequality.

Weimin Chen, Yongbin Ruan

This is a research announcement of the theory of orbifold quantum cohomology.

Victor Ginzburg

Quiver varieties have recently appeared in various different areas of Mathematics such as representation theory of Kac-Moody algebras and quantum groups, instantons on 4-manifolds, and resolutions Kleinian singularities. In this paper, we show that many important affine quiver varieties, e.g., the Calogero-Moser space, can be imbedded as coadjoint orbits in

Wellington da Cruz

We consider a simple action for a fractional spin particle and a path integral representation for the propagator is obtained in a gauge such that the constraint embodied in the Lagrangian is not an obstacle. We obtain a propagator for the particle in a constant electromagnetic field via the path integral representation over velocities, which is characterized

S. Alavian, T. G. Steele

Extended BRS symmetry is used to prove gauge independence of the fermion renormalization constant $Z_2$ in on-shell QED renormalization schemes. A necessary condition for gauge independence of $Z_2$ in on-shell QCD renormalization schemes is formulated. Satisfying this necessary condition appears to be problematic at the three-loop level in QCD.

Donam Youm

We give a microscopic explanation for the recently observed equivalence among thermodynamics of supergravity solutions for Dp-branes with or without NS B-field and for D(p-2)-branes with vanishing B-field and two delocalized transverse directions by showing that these D-brane configurations are related to one another through T-duality transformations. This r

Yoshitaka Degura, Kiyoshi Shiraishi

We consider the non-relativistic effective field theory of ``extreme black holes'' in the Einstein-Maxwell-dilaton theory with an arbitrary dilaton coupling. We investigate finite-temperature behavior of gas of ``extreme black holes'' using the effective theory. The total energy of the classical many-body system is also derived.

Vipul Periwal

The Cattaneo-Felder path integral form of the perturbative Kontsevich deformation quantization formula is used to explicitly demonstrate the existence of nonperturbative corrections to na\"ıve deformation quantization.

Dan Radu Grigore

The dilation invariance is studied in the framework of Epstein-Glaser approach to renormalization theory. Some analogues of the Callan-Symanzik equations are found and they are applied to the scalar field theory and to Yang-Mills models. We find the interesting result that, if all the fields of the theory have zero masses, then from purely cohomological cons

Robert Bluhm

A review of Lorentz and CPT tests performed in atomic systems is presented. A theoretical framework extending QED in the context of the standard model is used to analyze a variety of systems. Experimental signatures of possible Lorentz and CPT violation in these systems are investigated. Estimated bounds attainable in future experiments and actual bounds obt

Tatsu Takeuchi, Oleg Lebedev, Will Loinaz

We discuss how new physics not encompassed within the STU oblique correction framework can be constrained from precision electroweak measurements via vertex corrections to Z-pole observables.

R. M. Godbole

In this talk, I discuss some aspects of Higgs searches at future colliders, particularly comparing and contrasting the capabilities of LHC and Next Linear Collider (NLC), including the aspects of Higgs searches in supersymmetric theories. After this, I will discuss how the search and study of sparticles other than the Higgs can give information about the par

M. Abud, F. Buccella

We determine the nu_{R} Majorana mass matrix from the experimental data on neutrino oscillations in the framework of a see-saw SO(10) model, where we impose the condition (M^R)_{33} = 0 to avoid too large fine-tunings in the see-saw formula. We find a class of solutions with the two lowest neutrino masses almost degenerate and the scale of the matrix element

W. Grimus, T. Schwetz

We consider elastic neutrino - electron scattering of solar neutrinos with magnetic moments and electric dipole moments, where the solar neutrino state at the scattering site is determined by the evolution in matter and solar magnetic fields of the initial electron neutrino state. We present the general cross section for an arbitrary superposition of active

R. Foot, H. Lew, R. R. Volkas

If the Lagrangian of nature respects parity invariance then there are two distinct possibilities: either parity is unbroken by the vacuum or it is spontaneously broken. We examine the two simplest phenomenologically consistent gauge models which have unbroken and spontaneously broken parity symmetries, respectively. These two models have a Lagrangian of the

Ken Sasaki, Tsuneo Uematsu

We investigate parton distributions in the virtual photon target, both polarized and unpolarized, up to the next-leading order (NLO) in QCD. Parton distributions can be predicted completely up to NLO, but they are factorization-scheme-dependent. We analyze parton distributions in several factorization schemes and discuss their scheme dependence. Particular a

K. Fialkowski, R. Wit

A recent proposal to study charge fluctuations as a possible signal of quark-gluon plasma is discussed. It is shown that the "pion gas model" considered as the reference sample is unrealistic and the expected signal from plasma may be difficult to distinguish from that coming from "standard collisions".

Y. Kiyo, J. Kodaira, K. Morii, T. Nasuno

We discuss top quark production and its subsequent decay at lepton colliders including both QCD corrections and anomalous gamma / Z - t t-bar couplings. The off-diagonal spin basis for the top and anti-top quarks is shown to be useful to probe the anomalous couplings.

Wojciech Broniowski

We show that the Hagedorn temperature obtained from experimental spectra is larger for mesons than for baryons. Dual string models explain this behavior asymptotically.

Sh. Matsumoto, M. Yoshimura

Time evolution of quantum tunneling is studied when the tunneling system is immersed in thermal medium. We analyze in detail the behavior of the system after integrating out the environment. Exact result for the inverted harmonic oscillator of the tunneling potential is derived and the barrier penetration factor is explicitly worked out as a function of time

Michael Schmelling

Properties of weighted averages are studied for the general case that the individual measurements are subject to hidden correlations and have asymmetric statistical as well as systematic errors. Explicit expressions are derived for an unbiased average with a well defined error estimate.

R. Appel, G. S. Atoyan, B. Bassalleck, D. Bergman

A search for lepton flavor violating decays, \kmmp, \keep, \kpem, \kmep and \pizem, was performed using the data collected in E865 at the Brookhaven Alternating Gradient Synchrotron. No signal was found in any of the decay modes. At the 90% confidence level, the branching ratios are less than $3.0\times10^{-9}$, $6.4\times10^{-10}$, $5.2\times10^{-10}$, $5.0

Alfredo Macias, Claus Laemmerzahl, Alberto Garcia

By using our recent generalization of the colliding waves concept to metric-affine gravity theories, and also our generalization of the advanced and retarded time coordinate representation in terms of Jacobi functions, we find a general class of colliding wave solutions with fourth degree polynomials in metric-affine gravity. We show that our general approac

Steven L. Liebling

Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical phenomena, discuss some recent results, and descri

John Ellis, N. E. Mavromatos, D. V. Nanopoulos

A toy calculation of string/D-particle interactions within a world-sheet approach indicates that quantum recoil effects - reflecting the gravitational back-reaction on space-time foam due to the propagation of energetic particles - induces the appearance of a microscopic event horizon, or `bubble', inside which stable matter can exist. The scattering eve

Joseph Y. Halpern, Yoram Moses

Reasoning about knowledge seems to play a fundamental role in distributed systems. Indeed, such reasoning is a central part of the informal intuitive arguments used in the design of distributed protocols. Communication in a distributed system can be viewed as the act of transforming the system's state of knowledge. This paper presents a general framework

Cynthia Dwork, Joseph Y. Halpern, O. Waarts

We consider a system of t synchronous processes that communicate only by sending messages to one another, and that together must perform $n$ independent units of work. Processes may fail by crashing; we want to guarantee that in every execution of the protocol in which at least one process survives, all n units of work will be performed. We consider three pa

Stephen Marsland, Ulrich Nehmzow, Jonathan Shapiro

In this paper a novelty filter is introduced which allows a robot operating in an un structured environment to produce a self-organised model of its surroundings and to detect deviations from the learned model. The environment is perceived using the rob ot's 16 sonar sensors. The algorithm produces a novelty measure for each sensor scan relative to the m

Stephen Marsland, Ulrich Nehmzow, Jonathan Shapiro

Recognising new or unusual features of an environment is an ability which is potentially very useful to a robot. This paper demonstrates an algorithm which achieves this task by learning an internal representation of `normality' from sonar scans taken as a robot explores the environment. This model of the environment is used to evaluate the novelty of ea

Stephen Marsland, Ulrich Nehmzow, Jonathan Shapiro

The ability of a robot to detect and respond to changes in its environment is potentially very useful, as it draws attention to new and potentially important features. We describe an algorithm for learning to filter out previously experienced stimuli to allow further concentration on novel features. The algorithm uses a model of habituation, a biological pro

S. A. Mondal

The problem of minimizing mean response time of generic jobs submitted to a heterogenous distributed computer systems is considered in this paper. A static load balancing strategy, in which decision of redistribution of loads does not depend on the state of the system, is used for this purpose. The article is closely related to a previous article on the same

Simon Kos

We discuss the basic physical mechanism of the d->d+is transition, which is the currently accepted explanation for the results of tunneling experiments into $ab$ planes. Using the first-order perturbation theory, we show that the zero-bias states drive the transition. We present various order-of-magnitude estimates and consistency checks that support this pi

Jung Hoon Han, Qiang-Hua Wang, Dung-Hai Lee

We study mean-field phases of the t-J model with long-range Coulomb interaction. In the order of increasing doping density we find a classical antiferromagnet, charge and spin stripes, and a uniform d-wave superconductor, at the realistic doping parameters. Both in-phase and anti-phase stripes exist as metastable configurations, but the in-phase stripes have

T. Cren, D. Roditchev, W. Sacks, J. Klein

In this Letter we present new tunneling data on YBa$_2$Cu$_3$O$_7$ thin films by low temperature scanning tunneling spectroscopy. Unusual peak-dip-hump features, previously reported in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$, are also found in YBa$_2$Cu$_3$O$_7$. To analyse these common signatures we propose a new heuristic model in which, in addition to the d-wave sy

K. Rejmer, M. Napiorkowski

Mean field analysis of the effective interfacial Hamiltonian shows that with increasing temperature the adsorption on a periodically corrugated substrate can proceed in two steps: first, there is the filling transition in which the depressions of the substrate become partially or completely filled; then there is the wetting transition at which the substrate

R. Malek, N. Mousseau

The potential energy surface (PES) of Lennard-Jones clusters is investigated using the activation-relaxation technique (ART). This method defines events in the configurational energy landscape as a two-step process: (a) a configuration is first activated from a local minimum to a nearby saddle-point and (b) is then relaxed to a new minimum. Although ART has

G. Bastian

In ballistic Josephson junctions the experimentally observed iv-characteristics deviate from the theoretically predicted behaviour. Recently, Heida et al. Phys. Rev. B 60, 13135 (1999) discussed this problem and offered an explanation for the discrepancy. Considering this explanation, several contradictions to the authors' data as well as to other public

O. M. Schmitt, D. B. Tran Thoai, P. Gartner, H. Haug

The dephasing and relaxation kinetics of bosonic excitons interacting with a thermal bath of acoustic phonons is studied after coherent pulse excitation. The kinetics of the induced excitonic polarization is calculated within Markovian equations both for subcritical and supercritical excitation with respect to a Bose-Einstein condensation (BEC). For excited

T. Cren, D. Roditchev, W. Sacks, J. Klein

Using high speed scanning tunneling spectroscopy, we perform a full mapping of the quasiparticle density of states (DOS) in single crystals of BiPbSrCaCuO(2212). The measurements carried out at 5 K showed a complex spatial pattern of important variations of the local DOS on the nanometer scale. Superconducting areas are co-existing with regions of a smooth a

Hideaki Aoyama, Yuichi Nagahara, Mitsuhiro P. Okazaki, Wataru Souma

We analyze the distribution of income and income tax of individuals in Japan for the fiscal year 1998. From the rank-size plots we find that the accumulated probability distribution of both data obey a power law with a Pareto exponent very close to -2. We also present an analysis of the distribution of the debts owed by bankrupt companies from 1997 to March,

C. H. W. Barnes, J. M. Shilton, A. M. Robinson

We describe in detail a set of ideas for implementing qubits, quantum gates and quantum gate networks in a semiconductor heterostructure device. Our proposal is based on an extension of the technology used for surface acoustic wave (SAW) based single-electron transport devices. These devices allow single electrons to be captured from a two-dimensional electr

Roser Valenti, Claudius Gros, Wolfram Brenig

We present a unified account of magnetic exchange and Raman scattering in the quasi-one-dimensional transition-metal oxide NaV$_2$O$_5$. Based on a cluster-model approach explicit expressions for the exchange integral and the Raman-operator are given. It is demonstrated that a combination of the electronic-structure and the Dzyaloshinskii-Moriya interaction,

P. Singha Deo, A. M. Jayannavar

Mesoscopic systems have provided an opportunity to study quantum effects beyond the atomic realm. In these systems quantum coherence prevails over the entire sample. We discuss several novel effects related to persistent currents in open systems which do not have analogues in closed systems. Some phenomena arising simultaneously due to two non-classical effe

J. J. Hogan-O'Neill, J. F. Annett, A. M. Martin

A closed superconducting circuit containing an odd number of $π$-junctions, a $π$-ring, has a finite current in the ground state. We explicitly construct such rings for d-wave superconductors and demonstrate the existence of spontaneous currents by direct self-consistent solutions to the Bogoliubov de Gennes equations. We show that the current has a topologi

Shigeru Koikegami, Kosaku Yamada

We analyze the two-dimensional {\it d-p} model, considering both antiferromagnetic spin fluctuation and $d_{x^2-y^2}$-wave superconducting fluctuation. We adopt the fluctuation-exchange approximation in order to derive both normal and anomalous vertices composed only of the renormalized {\it d}-electron Green function and the on-site repulsive interaction am

Tooru Taniguchi

A method to derive the charge current density and its quantum mechanical correlation from the scattering matrix is discussed for quantum scattering systems described by a time-dependent Hamiltonian operator. The current density and charge density are expressed with the help of functional derivatives with respect to the vector potential and the electric poten

Uffe V. Poulsen, Klaus Molmer

We analyse the atomic state obtained by photo-dissociation of a molecular Bose-Einstein-condensate. This process is equivalent to down-conversion in quantum optics where it is responsible for squeezing of the field amplitudes. Monte Carlo simulations derived from the Positive P description of the system, and approximate equations for second moments of the at

O. Narikiyo

Theories of the magnetotransport, based on the quasipartricle of the Fermi-liquid, in the normal state of high-Tc cuprate superconductors, are critically examined and the necessity of the collective transport theory beyond the quasiparticle is discussed.

Bae-Yeun Ha

We propose a mechanism for the stabilization/destabilization of cell membranes by multivalent ions with an emphasis on its implications for the division and fusion of cells. We find that multivalent cations preferentially adsorbed onto a membrane dramatically changes the membrane stability. They not only reduce the surface charge density of the membrane but

Lisa J. Storrie-Lombardi, Arthur M. Wolfe

We have completed spectroscopic observations using LRIS on the Keck 1 telescope of 30 very high redshift quasars, 11 selected for the presence of damped Ly-alpha absorption systems and 19 with redshifts z > 3.5 not previously surveyed for absorption systems. We have surveyed an additional 10 QSOs with the Lick 120'' and the Anglo-Australian Telescope

S. George Djorgovski, Robert J. Brunner

Large digital sky surveys, over a broad range of wavelengths, both from the ground and from space observatories, are becoming a major source of astronomical data. Some examples include the Sloan Digital Sky Survey (SDSS) and the Digital Palomar Observatory Sky Survey (DPOSS) in the visible, the Two-Micron All-Sky Survey (2MASS) in the near-infrared, the NRAO

Thomas J. Maccarone, Paolo S. Coppi, Juri Poutanen

We use time domain analysis techniques to investigate the rapid variability of Cygnus X-1. We show that the cross-correlation functions between hard and soft energy bands reach values very close to unity and peak at a lag of less than 2 millisecond for energies separated by a factor of 10. This confirms that the process that produces X-ray photons at differe

Helen Valentine, Will Saunders, Andy Taylor

We present a generalized version of the Path Interchange Zel'dovich Approximation (PIZA), for use with realistic galaxy redshift surveys. PIZA is a linear particle-based Lagrangian method which uses the present day positions of galaxies to reconstruct both the initial density field and the present day peculiar velocity field. We generalize the method by

R. Ferlet, M. Andre, G. Hebrard, A. Lecavelier-des-Etangs

The Lyman and Werner band systems of deuterated molecular hydrogen (HD) occur in the far UV range below 1200 A. The high sensitivity of the FUSE mission can give access, at moderate resolution, to hot stars shining through translucent clouds, in the hope of observing molecular cores in which deuterium is essentially in the form of HD. Thus, the measurement o

P. -A. Duc, E. Brinks, V. Springel, B. Pichardo

Among the various phenomena observed in interacting galaxies is the ejection due to tidal forces of material into the intergalactic medium and its subsequent rearranging which can lead to the formation of self-gravitating tidal dwarf galaxies (TDGs). We investigate this process with a detailed multiwavelength study of the interacting system Arp 245 (NGC 2992

Remo J. Ruffini

We recall the generalization of the Feynman-Metropolis-Teller approximation for a compressed atom using a relativistic Fermi-Thomas model. These results within a Wigner-Seitz approximation lead to a new equation of state for white dwarfs and to a new value of their critical mass, smaller than the one obtained by Chandrasekhar. The possible observations of th

G. Bertone, R. Ruffini

The Feynman-Metropolis-Teller treatment for compressed atoms is here reconsidered in the framework of the relativistic generalised Fermi-Thomas model, obtained by Ruffini et al. Physical properties of a zero temperature plasma is thus investigated and the resulting equation of state, which keeps into account quantum, relativistic and electromagnetic effects,

Ken'ichi Torii, Patrick O. Slane, Kenzo Kinugasa, Kiyoshi Hashimotodani

We present here the X-ray observation of a Crab-like supernova remnant (SNR) 3C58 with ASCA. We find that the integrated energy spectrum over the nebula is consistent with previous results, showing a power-law spectrum with the photon index $γ= 2.2-2.4$ modified by interstellar absorption of about $(3-4)\times 10^{21}{\rm cm^{-2}}$. Inclusion of a blackbody

Ted von Hippel, Gerard Gilmore

We have used deep HST WFPC2 observations of two fields in NGC 2420 to produce a cluster CMD down to V = 27. After imposing morphological selection criteria we find eight candidate white dwarfs in NGC 2420. Our completeness estimates indicate that we have found the terminus of the WD cooling sequence. We argue that the cluster distance modulus is likely to be

Shyamoli Chaudhuri, Eric G. Novak

We show that the one loop amplitudes of open and closed string theory in a constant background two-form tensor field are characterized by an effective string tension larger than the fundamental string tension, and by the appearance of antisymmetric and symmetric noncommutativity parameters. We derive the form of the phase functions normalizing planar and non

Guang-Hong Chen, Yong-Shi Wu

In this paper we study the interplay of electric and magnetic backgrounds in determining the decoupling limit of coincident D-branes towards a noncommutative Yang-Mills (NCYM) or open string (NCOS) theory. No decoupling limit has been found for NCYM with space-time noncommutativity. It is suggested that there is a new duality, which we call V-duality, which

N. Michael Davies, Timothy J. Hollowood, Valentin V. Khoze

We examine the low-energy dynamics of four-dimensional supersymmetric gauge theories and calculate the values of the gluino condensate for all simple gauge groups. By initially compactifying the theory on a cylinder we are able to perform calculations in a controlled weakly-coupled way for small radius. The dominant contributions to the path integral on the

Paul B. Slater

We address the "major open problem" of evaluating how much increased efficiency in estimation is possible using non-separable, as opposed to separable, measurements of N copies of m-level quantum systems. First, we study the six cases m = 2, N = 2,...,7 by computing the the 3 x 3 Fisher information matrices for the corresponding optimal measurements recently

L. J. Lising, S. R. Hwang, J. M. Adams, T. J. Bowles

We describe an experiment that has set new limits on the time reversal invariance violating D coefficient in neutron beta-decay. The emiT experiment measured the angular correlation J . p_e x p_p using an octagonal symmetry that optimizes electron-proton coincidence rates. The result is D=[-0.6+/-1.2(stat)+/-0.5(syst)]x10^(-3). This improves constraints on t

J. Alvarez-Muniz, F. Halzen, D. W. Hooper

Following Waxman and Bahcall we calculate the event rate, energy and zenith angle dependence of neutrinos produced in the fireball model of gamma ray bursts (GRB). We emphasize the primary importance of i) burst-to-burst fluctuations and ii) absorption of the neutrinos in the Earth. From the astronomical point of view, we draw attention to the sensitivity of

Tsutomu Momoi, Keisuke Totsuka

We study the Heisenberg antiferromagnet on the Shastry-Sutherland lattice under magnetic fields, to clarify the magnetic properties of SrCu_2(BO_3)_2. Treating magnetic excitations promoted by the field as Bose particles and using strong coupling expansion, we derive an effective Hamiltonian for the effective magnetic particles. Anisotropic repulsive interac

S. Ferrara, C. Fronsdal

We generalize, to any space-time dimension, the unitarity bounds of highest weight UIR's of the conformal groups with Lie algebras $so(2,d)$. We classify gauge theories invariant under $so(2,d)$, both integral and half-integral spins. A similar analysis is carried out for the algebras $so^*(2n)$. We study new unitary modules of the conformal algebra in $

G. Balestrino, S. Lavanga, S. Martellucci, P. G. Medaglia

The electrical transport properties of [BaCuO_x]_2/[CaCuO_2]_n (CBCCO-2xn)underdoped high temperature superconducting superlattices grown by Pulsed Laser Deposition have been investigated. Starting from the optimally doped CBCCO-2x2 superlattice, having three CuO_2 planes and T_c around 80 K, we have systematically increased the number n up to 15 moving towa

S. J. Dong, F. X. Lee, K. F. Liu, J. B. Zhang

The chiral symmetry relation and scaling of the overlap fermions are studied numerically on the quenched lattices at 3 couplings with about the same physical volume. We find that the generalized Gell-Mann-Oakes-Renner relation is satisfied to better than 1% down to the smallest quark mass at $m_0a = 0.006$. We also obtain the quark mass from the PCAC relatio

Teruyuki Kitabayashi, Masaki Yasue

Two-loop radiative mechanism, when combined with an U(1)_{L'} symmetry generated by L_e-L_μ-L_τ(=L'), is shown to provide an estimate of Δm^2_{\odot}/Δm^2_{atm} $\sim$ εm_e/m_τ, where εmeasures the U(1)_{L'}-breaking. Since Δm^2_{atm} $\sim 3.5x10^{-3} eV^2, we find that Δm^2_{\odot} $\sim$ εx10^{-6} eV^2, which will fall into the allowed region

T. Matos, L. A. Urena-Lopez

We present the complete solution to a 95% scalar field cosmological model in which the dark matter is modeled by a scalar field $Φ$ with the scalar potential $V(Φ)=V_{o}[ \cosh {(λ\sqrt{κ_{o}}Φ)}-1]$ and the dark energy is modeled by a scalar field $Ψ$, endowed with the scalar potential $\tilde{V}(Ψ)=\tilde{V_{o}}[ \sinh {(α\sqrt{κ_{o}}Ψ)}] ^β$. This model h

P. Pieri, G. C. Strinati, I. Tifrea

We consider a two-dimensional dilute Bose gas above its superfluid transition temperature. We show that the t-matrix approximation corresponds to the leading set of diagrams in the dilute limit, provided the temperature is sufficiently larger than the superfluid transition temperature. Within this approximation, we give an explicit expression for the wave ve

David Langlois, Roy Maartens, David Wands

We discuss the evolution of gravitational waves in a brane-world cosmology embedded in five-dimensional anti-de Sitter spacetime. We show that during slow-roll inflation, modelled as a period of quasi-de Sitter expansion on the brane, there is a discrete normalizable massless graviton mode. There is a mass gap due to the expansion, above which there is a con

D. Bartz, Fl. Stancu

We study the nucleon-nucleon interaction within a chiral constituent quark model which reproduces succesfully the baryon spectra. We calculate the 3S1 and 1S0 phase shifts by using the resonating group method. They clearly indicate the presence of a strong repulsive interaction at short distance, due to the spin-flavor symmetry of the quark-quark interaction

P. Aurenche, L. Bourhis, M. Fontannaz, J. Ph. Guillet

We present a method for calculating the photoproduction of jets at HERA based on Next to Leading Logarithm QCD calculations. It is implemented in a Monte-Carlo generator which allows us to easily compute any infra-red safe cross sections for 1 or 2 jet observables using various jet reconstruction algorithms. We focus on the possibility of extracting the gluo

Luis E Mendes, Andrew R Liddle

In hybrid inflation models, typically only a tiny fraction of possible initial conditions give rise to successful inflation, even if one assumes spatial homogeneity. We analyze some possible solutions to this initial conditions problem, namely assisted hybrid inflation and hybrid inflation on the brane. While the former is successful in achieving the onset o

E. S. Zijlstra, T. Janssen

The density of states of the ideal three-dimensional Penrose tiling, a quasicrystalline model, is calculated with a resolution of 10 meV. It is not spiky. This falsifies theoretical predictions so far, that spikes of width 10-20 meV are generic for the density of states of quasicrystals, and it confirms recent experimental findings. The qualitative differenc

Sunanda Banerjee, Rahul Basu

We consider the effects of quark masses to the perturbative thrust in $e^+e^-$ annihilation. In particular we show that perturbative power corrections resulting from non-zero quark masses considerably alters the size of the non-perturbative power corrections and consequently, significantly changes the fitted value of $α_s$.

Nathan Berkovits

A manifestly super-Poincaré covariant formalism for the superstring has recently been constructed using a pure spinor variable. Unlike the covariant Green-Schwarz formalism, this new formalism is easily quantized with a BRST operator and tree-level scattering amplitudes have been evaluated in a manifestly covariant manner. In this paper, the cohomology of th

F. De Fazio, M. R. Pennington

The radiative transitions $ϕ\to ηγ$ and $ϕ\to η^\prime γ$ are analysed using QCD sum-rules. The results we obtain for ${\cal B}(ϕ\to ηγ)=(1.15 \pm 0.2) 10^{-2}$ and ${\cal B}(ϕ\to η^\prime γ)=(1.18 \pm 0.4) 10^{-4}$ are in very good agreement with existing experimental data. The related issue of $η-η^\prime$ mixing is discussed and we give predictions for th

V. S. Gerdjikov, G. G. Grahovski, N. A. Kostov

The analysis and the classification of all reductions for the nonlinear evolution equations solvable by the inverse scattering method is an interesting and still open problem. We show how the second order reductions of the N-wave interactions related to low-rank simple Lie algebras g can be embedded also in the Weyl group of g. This allows us to display alon

A. N. Ionov, V. A. Zakrevskii, J. M. Lazebnik, R. Rentzsch

We have observed that thin films of amorphous polyimide placed between two metallic electrodes become highly conducting with no applied electric field, and at a low pressure which was necessary only to achieve reliable electrical contact with the metallic electrodes. We observed for the first time a Josephson effect in a sandwich of a superconductor - polyim

Ralf Klessen, Andreas Burkert

Using hydrodynamic simulations we investigate the time evolution and fragmentation of regions within molecular clouds which have lost their turbulent support leading to gravitational contraction. The initial density distributions are described by random Gaussian fluctuations with varying slopes x of the power spectrum P(k) ~ k^-x, covering the range from fla

Uma Mahanta, Subhendra Mohanty

In this paper we construct the interaction potential between the dense supernova core and neutrinos due to the exchange of light radions in the Randall-Sundrum scenario. We then show that the radion exchange potential affects the neutrino oscillation phenomenology inside the supernova significantly if the radion mass is less than around 1 GeV. In order that