July 2000 arXiv papers — page 7

HEGRA Collaboration, F. Aharonian

The HEGRA system of imaging atmospheric Cherenkov telescopes provides for specially selected classes of events an angular resolution of better than 3'. By comparing the measured angular distribution of TeV gamma rays from the Crab Nebula with the distribution expected on the basis of Monte Carlo simulations, and with measurements of gamma rays from the p

A. A. Deshpande, K. S. Dwarakanath, W. M. Goss

We have obtained the power spectral description of the density and opacity fluctuations of the cold HI gas in the Galaxy towards Cas A, and Cygnus A. We have employed a method of deconvolution, based on CLEAN, to estimate the true power spectrum of optical depth of cold HI gas from the observed distribution, taking into account the finite extent of the backg

Chanda J. Jog

We calculate the self-consistent response of an axisymmetric galactic disk perturbed by an elliptical halo potential of harmonic number m = 2, and obtain the net disk ellipticity. Such a potential is commonly expected to arise due to a galactic tidal encounter and also during the galaxy formation process. The self-gravitational potential corresponding to the

R. Fux

The effects of the Galactic bar on the velocity distribution of old disc stars in the Solar neighbourhood are investigated using high-resolution 2D test particle simulations. A detailed orbital analysis reveals that the structure of the U-V distribution in these simulations is closely related to the phase-space extent of regular and chaotic orbits. At low an

C. S. Frenk, J. M. Colberg, H. M. P. Couchman, G. Efstathiou

We are making available on the WWW a selection of the archived data from N-body simulations carried out by the Virgo consortium and related groups. This currently includes: (i) time-slice, lightcone and cluster data from the two $10^9$-particle Hubble volume simulations described by Evrard 1998; (ii) time-slice data from simulations of 4 different cold dark

J. A. Tyson, David Wittman, J. R. P. Angel

Weak gravitational lensing enables direct reconstruction of dark matter maps over cosmologically significant volumes. This research is currently telescope-limited. The Dark Matter Telescope (DMT) is a proposed 8.4 m telescope with a 3 degree field of view, with an etendue of 260 $(m. degree)^2$, ten times greater than any other current or planned telescope.

Giulia Iori

We propose a model with heterogeneous interacting traders which can explain some of the stylized facts of stock market returns. In the model synchronization effects, which generate large fluctuations in returns, can arise either from an aggregate exogenous shock or, even in its absence, purely from communication and imitation among traders. A trade friction

Chulwoo Jung, Valeriya Gadiyak, Xiangdong Ji, Robert G. Edwards

We study the effective quark mass induced by the finite separation of the domain walls in the domain-wall formulation of chiral fermion as the function of the size of the fifth dimension ($L_s$), the gauge coupling $β$ and the physical volume $V$. We measure the mass by calculating the small eigenvalues of the hermitian domain-wall Dirac operator ($H_{\rm DW

E. F. Suisso, W. R. B. de Araujo, T. Frederico, M. Beyer

We investigate the effect of different relativistic spin couplings of constituent quarks on nucleon electroweak properties. Within each quark spin coupling scheme the correlations between static electroweak observables are found to be independent of the particular shape of the momentum part of the nucleon light-front wave function. The neutron charge form fa

CLEO collaboration

Using 13.7 fb^{-1} of data recorded by the CLEO detector at CESR, we report preliminary evidence for two new charmed baryons; one decaying into Xi_c^{0\prime} pi^+ with the subsequent decay Xi_c^{0\prime} to Xi_c^0 gamma, and its isospin partner decaying into Xi_c^{+\prime} pi^- followed by Xi_c^{+\prime} to Xi_c^+ gamma. We measure the following mass differ

Igor R. Klebanov, Matthew J. Strassler

We revisit the singular IIB supergravity solution describing M fractional 3-branes on the conifold [hep-th/0002159]. Its 5-form flux decreases, which we explain by showing that the relevant \NN=1 SUSY SU(N+M)xSU(N) gauge theory undergoes repeated Seiberg-duality transformations in which N -> N-M. Far in the IR the gauge theory confines; its chiral symmetry b

CLEO collaboration

Using 13.7 fb^{-1} of data recorded by the CLEO detector at CESR, we investigate the spectrum of charmed baryons which decay into Lambda_c^+ pi^- pi^+ and are more massive than the Lambda_{c1} baryons. We find evidence for two new states: one is broad and has an invariant mass roughly 480 MeV above that of the Lambda_c^+; the other is narrow with an invarian

J. M. Mira, E. Nardi, D. A. Restrepo, J. W. F. Valle

We study extensions of supersymmetric models without R-parity which include an anomalous U(1)_H horizontal symmetry. Bilinear R-parity violating terms induce a neutrino mass at tree level of approximately $(θ^2)^δ$ eV where $θ\approx 0.22$ is the U(1)_H breaking parameter and $δ$ is an integer number that depends on the horizontal charges of the leptons. For

Byron P. Roe, Michael B. Woodroofe

We propose using a Bayes procedure with uniform improper prior to determine credible belts for the mean of a Poisson distribution in the presence of background and for the continuous problem of measuring a non-negative quantity $θ$ with a normally distributed measurement error. Within the Bayesian framework, these belts are optimal. The credible limits are t

Anupam Mazumdar

We discuss cosmology in four dimensions within a context of brane-world scenario.Such models can predict chaotic inflation with very low reheat temperature depending on the brane tension. We notice that the gravitino abundance is different in the brane-world cosmology and by tuning the brane tension it is possible to get extremely low abundance. We also stud

E. Farhi, N. Graham, R. L. Jaffe, H. Weigel

We compute fractional and integer fermion quantum numbers of static background field configurations using phase shifts and Levinson's theorem. By extending fermionic scattering theory to arbitrary dimensions, we implement dimensional regularization in a 1+1 dimensional gauge theory. We demonstrate that this regularization procedure automatically eliminat

Z. Y. Chen, Amlan Biswas, Igor Zutic, T. Wu

Transport across an La$_{0.7}$Sr$_{0.3}MnO$_{3}/YBa$_{2}Cu$_{3}$O$_{7}$(LSMO/YBCO), interface is studied as a function of temperature and surface morphology. For comparison, control measurements are performed in non-magnetic heterostructures of LaNiO$_{3}$/YBCO and Ag/YBCO. In all cases, YBCO is used as bottom layer to eliminate the channel resistance and to

D. Karabali, C. Kim, V. P. Nair

In earlier work we have given a Hamiltonian analysis of Yang-Mills theory in (2+1) dimensions showing how a mass gap could arise. In this paper, generalizing and covariantizing from the mass term in the Hamiltonian analysis, we obtain two manifestly covariant and gauge-invariant mass terms which can be used in a resummation of standard perturbation theory to

Paolo Creminelli, Alessandro Strumia

Assuming that we live on a non rigid brane with TeV-scale tension, the scalar fields that control the coordinates of our brane in the extra dimensions give rise to missing energy signals at high-energy colliders with a characteristic angular and energy spectrum, identical to the one due to graviton emission in 6 extra dimensions. LEP bounds and LHC capabilit

J. S. B. Wyithe, E. L. Turner, D. N. Spergel

Strong lensing is a powerful probe of the distribution of matter in the cores of clusters of galaxies. Recent studies suggest that the cold dark matter model predicts cores that are denser than those observed in galaxies, groups and clusters. One possible resolution of the discrepancy is that the dark matter has strong interactions (SIDM), which leads to low

S. Peng Oh, Zoltan Haiman, Martin J. Rees

The hardness of the ionizing continuum from the first sources of UV radiation plays a crucial role in the reionization of the intergalactic medium (IGM). While usual stellar populations have soft spectra, mini-quasars or metal-free stars with high effective temperatures may emit hard photons, capable of doubly ionizing helium and increasing the IGM temperatu

M. T. Hussein, N. M. Hassan, N. Elharby

The hypothesis of the multi peripheral model is extended to the hadron-nucleus interactions and then generalized to the nucleus-nucleus case. The processing of the model depends on input parameters that are extracted from the features of the experiments in this field. The number of encountered nucleons from both target and projectile are estimated according

Juan P. Garrahan, M. E. J. Newman

We study the low temperature dynamics of a two dimensional short-range spin system with uniform ferromagnetic interactions, which displays glassiness at low temperatures despite the absence of disorder or frustration. The model has a dual description in terms of free defects subject to dynamical constraints, and is an explicit realization of the ``hierarchic

S. I. Simdyankin, M. Dzugutov, S. N. Taraskin, S. R. Elliott

We compare vibrational dynamics in two structurally distinct, simple monatomic model glasses simulated by molecular dynamics: the Lennard-Jones glass with an fcc-related structure and a glass with predominantly icosahedral short-range order. The former, characterised by a single local quasi-periodicity, supports only modes with acoustic behaviour. In the lat

C. Palenzuela, R. Toral, C. R. Mirasso, O. Calvo

We show that it is possible for chaotic systems to display the main features of coherence resonance. In particular, we show that a Chua model, operating in a chaotic regime and in the presence of noise, can exhibit oscillations whose regularity is optimal for some intermediate value of the noise intensity. We find that the power spectrum of the signal develo

M. Mazzocco

In this paper, we classify all values of the parameters $α$, $β$, $γ$ and $δ$ of the Painlevé VI equation such that there are rational solutions. We give a formula for them up to the birational canonical transformations and the symmetries of the Painlevé VI equation.

Prabodh Shukla

We obtain exact expressions for the minor hysteresis loops in the ferromagnetic random field Ising model on a Bethe lattice at zero temperature in the case when the driving field is cycled infinitely slowly.

V. B. Eltsov, T. W. B. Kibble, M. Krusius, V. M. H. Ruutu

Spin-mass vortices have been observed to form in rotating superfluid 3He-B following the absorption of a thermal neutron and a rapid transition from the normal to superfluid state. The spin-mass vortex is a composite defect which consists of a planar soliton (wall) which terminates on a linear core (string). This observation fits well within the framework of

CLEO collaboration

The CLEO detector at the CESR collider has used 13.7 fb^{-1} to search for the production of Omega_c (css-ground state) in e^{+}e^{-} collisions at sqrt{s} = 10.6 GeV The modes used to study the Omega_c are Omega- pi+, Omega- pi+ pi0, Xi- K- pi+ pi+, Xi0 K- pi+, and Omega- pi+ pi+ pi-. We observe 40.4 +- 9.0(stat) combined events at a mass of 2694.6 +- 2.6(s

CLEO collaboration

Using a sample of 9.7 million B meson pairs collected with the CLEO detector, we study inclusive B meson decays to the chi_c1 and chi_c2 charmonia states. We measure the branching fraction for the inclusive chi_c1 production in B decays to be Br(B->chi_c1 X)=(4.14+-0.31+-0.40)*10^-3, where the first uncertainty is statistical and the second one is systematic

J. M. Flynn, J. Nieves

We use the Omnes representation to obtain the q-squared dependence of the form factors f+ and f0 for semileptonic H -> pi decays from the elastic pi H -> pi H scattering amplitudes, where H denotes a B or D meson. The scattering amplitudes used satisfy elastic unitarity and are calculated from two-particle irreducible amplitudes obtained using tree-level hea

Michael B. Mensky, Igor D. Novikov

Self-collision of a non-relativistic classical point-like body, or particle, in the spacetime containing closed time-like curves (time-machine spacetime) is considered. A point-like body (particle) is an idealization of a small ideal elastic billiard ball. The known model of a time machine is used containing a wormhole leading to the past. If the body enters

E. Gotsman, E. Levin, M. Lublinsky, U. Maor

We gereralize the Kochegov-McLerran formula for the ratio $σ^{DD}/σ_{tot}$ in perturbative QCD, using Mueller-Glauber approach for shadowing corrections and AGK cutting rules. We investigate several phenomenological approaches with the goal of obtaining results consisent with experimental data. We fail to reproduce the observed weak energy dependence of the

E. Gotsman, E. Levin, U. Maor, L. McLerran

We show that the ratio of different structure functions have a maximum which depends on $x_B$ and $A$. We argue that these maxima are proportional to the saturation scale. The analysis of leading and higher twist contributions for different observables is given with the aim of determining the kinematic region where high parton density effects could be seen e

Jorge Kurchan

We consider a quantum system strongly driven by forces that are periodic in time. The theorem concerns the probability $P(e)$ of observing a given energy change $e$ after a number of cycles. If the system is thermostated by a (quantum) thermal bath, $e$ is the total amount of energy transferred to the bath, while for an isolated system $e$ is the increase in

M. Hindmarsh, A. Rajantie

We propose a new mechanism for formation of topological defects in a U(1) model with a local gauge symmetry. This mechanism leads to definite predictions, which are qualitatively different from those of the Kibble-Zurek mechanism of global theories. We confirm these predictions in numerical simulations, and they can also be tested in superconductor experimen

Masashi Naganuma, Muneto Nitta

We consider BPS domain walls in the four dimensional N=1 supersymmetric models with continuous global symmetry. Since the BPS equation is covariant under the global transformation, the solutions of the BPS walls also have the global symmetry. The moduli space of the supersymmetric vacua in such models have non-compact flat directions, and the complex BPS wal

Leo Girardi, Maurizio Salaris

(Abridged) The red giant clump has been recently argued to be a reliable distance indicator for the galaxies in the Local Group. We re-address the problem of the systematic magnitude differences (DeltaM_I) between the local clump revealed by Hipparcos, and the clump stars observed in distant galaxies. First, we present tables and equations with the theoretic

P. Blanchard, S. Digal, S. Fortunato, D. Gandolfo

The spontaneous symmetry breaking in the Ising model can be equivalently described in terms of percolation of Wolff clusters. In O(n) spin models similar clusters can be built in a general way, and they are currently used to update these systems in Monte Carlo simulations. We show that for 3-dimensional O(2), O(3) and O(4) such clusters are indeed the physic

Noriaki Kitazawa, Nobuhito Maru, Nobuchika Okada

We propose a simple scenario of the dynamical supersymmetry breaking in four dimensional supergravity theories. The supersymmetry breaking sector is assumed to be completely separated as a sequestered sector from the visible sector, except for the communication by the gravity and U(1)_R gauge interactions, and the supersymmetry breaking is mediated by the su

C. García-Recio, L. L. Salcedo

A method is presented for the computation of the one-loop effective action at finite temperature and density. The method is based on an expansion in the number of spatial covariant derivatives. It applies to general background field configurations with arbitrary internal symmetry group and space-time dependence. Full invariance under small and large gauge tr

Guy Hed, Alexander K. Hartmann, Dietrich Stauffer, Eytan Domany

Unbiased samples of ground states were generated for the short-range Ising spin glass with Jij=+/-1, in three dimensions. Clustering the ground states revealed their hierarchical structure, which is explained by correlated spin domains, serving as cores for macroscopic zero energy "excitations".

Y. Kiyo, Y. Sumino

Presently the quarkonium spectrum, written in terms of the quark MSbar-mass, is known at O(alpha_s^3 m) accuracy. We point out that in order to achieve O(alpha_s^4 m) accuracy it is sufficient to calculate further (I) the O(alpha_s^4 m) relation between the MSbar-mass and the pole-mass, and (II) the binding energy at O(alpha_s^5 m) in the large-beta_0 approx

A. Mershin, D. V. Nanopoulos, E. M. C. Skoulakis

In order to create a novel model of memory and brain function, we focus our approach on the sub-molecular (electron), molecular (tubulin) and macromolecular (microtubule) components of the neural cytoskeleton. Due to their size and geometry, these systems may be approached using the principles of quantum physics. We identify quantum-physics derived mechanism

K. V. Krutitsky, K. -P. Marzlin, J. Audretsch

Starting from the first principles of nonrelativistic QED we have developed the quantum theory of the interaction of a two-component ultracold atomic ensemble with the electromagnetic field of vacuum and laser photons. The main attention has been paid to the consistent consideration of dynamical dipole-dipole interactions in the radiation field. Taking into

Masato Koashi, Vladimir Buzek, Nobuyuki Imoto

Quantum entanglement cannot be unlimitedly shared among arbitrary number of qubits. Larger the number of entangled pairs in an N-qubit system, smaller the degree of bi-partite entanglement is. We analyze a system of N qubits in which an arbitrary pair of particles is entangled. We show that the maximum degree of entanglement (measured in the concurrence) bet

Horst von Borzeszkowski, Michael B. Mensky

The realization of the Einstein-Podolsky-Rosen effect by the correlation of spin projections of two particles created in the decay of a single scalar particle is considered for particles propagating in gravitational field. The absence of a global definition of spatial directions makes it unclear whether the correlation may exist in this case and, if yes, wha

Mark Hillery, Peter D. Drummond

We study the scattering of the quantized electromagnetic field from a linear, dispersive dielectric using the scattering formalism for quantum fields. The medium is modeled as a collection of harmonic oscillators with a number of distinct resonance frequencies. This model corresponds to the Sellmeir expansion, which is widely used to describe experimental da

Masahito Hayashi

This paper has been withdrawn by the author. Lemma 8 is used in the proof of Lemma 6, but it is not correct. Lemma 6 is essential for the main results.

Craig D. Roberts

Continuum strong QCD is the application of models and continuum quantum field theory to the study of phenomena in hadronic physics, which includes; e.g., the spectrum of QCD bound states and their interactions. Herein I provide a Dyson-Schwinger equation perspective, focusing on qualitative aspects of confinement and dynamical chiral symmetry breaking in col

A. Bianconi, G. Bonomi, M. P. Bussa, G. Gomez

We compare data of antineutron and antiproton annihilation cross sections on different targets at very low energies. After subtracting Coulomb effects, we observe that the ratio between the antineutron proton and antiproton proton annihilation cross sections is an oscillating function of the energy at momenta smaller 300 MeV/c. This nontrivial behavior is co

C. E. Alonso, M. V. Andres, J. M. Arias, E. G. Lanza

The coupling of the high-lying dipole mode to the low-lying quadrupole modes for the case of deformed gamma-unstable nuclei is studied. Results from the geometrical model are compared to those obtained within the dipole boson model. Consistent results are obtained in both models. The dipole boson model is treated within the intrinsic frame, with subsequent p

V. Paar, H. Buljan

The average lifetime ($τ(H)$) it takes for a randomly started trajectory to land in a small region ($H$) on a chaotic attractor is studied. $τ(H)$ is an important issue for controlling chaos. We point out that if the region $H$ is visited by a short periodic orbit, the lifetime $τ(H)$ strongly deviates from the inverse of the naturally invariant measure cont

Sergey Denisov

We consider model of a complex particle that consists of a rigid shell and a nucleus with spatial asymmetric interaction. The particle's dynamics with the nucleus driven by a periodic excitation is considered. It is shown that unidirectional self-propulsed particle motion arises in the absence of spatial and temporary asymmetry of external potentials and

Martin Scharlemann

An expository survey article on Heegaard splittings

Dave Witte

Let H be a closed, noncompact subgroup of a simple Lie group G, such that G/H admits an invariant Lorentz metric. We show that if G = SO(2,n), with n > 2, then the identity component of H is conjugate to the identity component of SO(1,n). Also, if G = SO(1,n), with n > 2, then the identity component of H is conjugate to the identity component of SO(1,n-1).

J. Scott Carter, Seiichi Kamada, Masahico Saito, Shin Satoh

Triple linking numbers were defined for 3-component oriented surface-links in 4-space using signed triple points on projections in 3-space. In this paper we give an algebraic formulation using intersections of homology classes (or cup products on cohomology groups). We prove that spherical links have trivial triple linking numbers and that triple linking num

Harrison Tsai, Uli Walther

Let K be a subfield of the complex numbers, and let D be the Weyl algebra of K-linear differential operators on K[x_1,...,x_n]. If M and N are holonomic left D-modules we present an algorithm that computes explicit generators for the finite dimensional vector space hom_D(M,N). This enables us to answer algorithmically whether two given holonomic modules are

David Iglesias, Juan C. Marrero

We study Jacobi structures on the dual bundle $A^\ast$ to a vector bundle $A$ such that the Jacobi bracket of linear functions is again linear and the Jacobi bracket of a linear function and the constant function 1 is a basic function. We prove that a Lie algebroid structure on $A$ and a 1-cocycle $ϕ\in Γ(A^\ast)$ induce a Jacobi structure on $A^\ast$ satisf

Bertfried Fauser

One particular approach to quantum groups (matrix pseudo groups) provides the Manin quantum plane. Assuming an appropriate set of non-commuting variables spanning linearly a representation space one is able to show that the endomorphisms on that space preserving the non-commutative structure constitute a quantum group. The non-commutativity of these variable

K. Bering

We consider the Hamiltonian treatment of non-local theories and Ostrogradski's formalism. This has recently also been discussed by Woodard (hep-th/0006207) and by Gomis, Kamimura and Llosa (hep-th/0006235). In our approach we recast the second class constraints into first class constraints and invoke the boundary Poisson bracket.

C. Farina, F. C. Santos, A. C. Tort

Using perturbative QED we show that, while the retarded dispersive force between an electrically polarizable atom and a magnetically polarizable one is proportional to $1/r^{8}$, where $r$ is the distance between the atoms, the non-retarded force is proportiaonal to $1/r^{5}$. This is a rather surprising result that should be compared with the dispersive van

T. Banks, W. Fischler

Motivated by a recent conjecture [1] that quantum corrections and the UV/IR connection modify the classical relation between SUSY breaking and the cosmological constant to the phenomenologically acceptable : $M_{SUSY} \sim M_P (Λ/M_P^4)^{1/8}$, we study SUSY breaking by boundary conditions in noncommutative field theories. In commutative field theory the vio

Ian G Moss

Heat kernel expansion coefficients are calculated for vacuum fluctuations with distributional background potentials and field strengths. Terms up to and including t^5/2 are presented.

A. W. Schreiber, R. Rosenfelder, C. Alexandrou

In order to understand QCD at the energies relevant to hadronic physics one requires analytical methods for dealing with relativistic gauge field theories at large couplings. Strongly coupled quenched QED provides an ideal laboratory for the development of such techniques, in particular as many calculations suggest that - like QCD - this theory has a phase w

A. M. Gago, H. Nunokawa, R. Zukanovich Funchal

We investigate the current status of the long-wavelength vacuum oscillation solution to the solar neutrino problem and to what extent the presence of a third neutrino can affect and modify it. Assuming that the smaller mass squared difference that can induce such oscillations, $Δm^2_{12}$, is in the range $10^{-11}-10^{-8}$ eV$^2$ and the larger one, $Δm^2_{

Nikolaos Kidonakis, J. F. Owens

Results for higher-order threshold enhancements in high-E_T jet production in hadron-hadron collisions are presented. Expressions are given for the next-to-next-to-leading order (NNLO) threshold corrections to the single-jet inclusive cross section at next-to-leading logarithmic (NLL) accuracy. The corrections are found to be small for the specific choice of

L. B. Okun, I. S. Tsukerman

The so-called equal velocity prescription for neutrino oscillations is forbidden kinematically.

Paolo Gambino, Ulrich Haisch

We compute the two-loop electroweak corrections to the radiative decays of the B meson in the SM. Electroweak effects reduce the Wilson coefficient C_7^eff(mw) by 2.6% for a light Higgs boson of about 100 GeV and are less important for a heavier Higgs. The leading term of a heavy top expansion of our result differs from the one obtained in the gaugeless appr

J. Forshaw, G. R. Kerley, G. Shaw

We employ values of the colour dipole cross section extracted from electroproduction and photoproduction data to show that gluon saturation effects are not required by the current HERA data but will become important in the THERA energy region.

M. Beneke, G. Buchalla, M. Neubert, C. T. Sachrajda

We examine some consequences of the QCD factorization approach to non-leptonic B decays into $πK$ and $ππ$ final states, including a set of enhanced power corrections. Among the robust predictions of the approach we find small strong-interaction phases (with one notable exception) and a pattern of CP-averaged branching fractions, which in some cases differ s

W. Krolikowski

The conjecture that among three massive neutrinos $ν_1, ν_2, ν_3$ there is no direct mixing between $ν_1$ and $ν_3$ leads to a two-mixing texture for three active neutrinos $ν_e, ν_μ, ν_τ$. This texture, much discussed previously, is neatly consistent with the observed deficits of solar $ν_e$'s and atmospheric $ν_μ$'s, but (without extra mixing with

Guido Altarelli, Ferruccio Feruglio, Isabella Masina

We construct and discuss a "realistic" example of SUSY SU(5) GUT model, with an additional U(1) flavour symmetry, that is not plagued by the need of large fine tunings, like those associated with doublet-triplet splitting in the minimal model, and that leads to an acceptable phenomenology. This includes coupling unification with a value of alpha_s(m_

C. Q. Geng, C. C. Lih, Wei-Min Zhang

We study the decays of $B_{s,d} \to l^+ l^- γ(l=e, μ,τ)$ within the light-front model. We calculate the tensor type form factors and use these form factors to evaluate the decay branching ratios. We find that, in the standard model, the branching ratios of $B_{s(d)} \to ł^+ ł^- γ$ ($ł=e, μ,τ$) are $7.1\times 10^{-9}$ ($1.5\times 10^{-10}$), $8.3\times 10^{-9

G. Ripka

The quantum fluctuations of the quark condensate are calculated using a regulated Nambu Jona-Lasinio model. The corresponding quantum fluctuations of the chiral fields are compared to those which are predicted by an ''equivalent'' sigma model. They are found to be large and comparable in size but they do not restore chiral symmetry. The resto

N. Haba, Tomoharu Suzuki

We comment on ``Linking solar and long baseline terrestrial neutrino experiments''

Gustavo R. Gonzalez-Martin

In a geometric unified theory there is an energy momentum equation, apart from the field equations and equations of motion. The general relativity Einstein equation with cosmological constant follows from this energy momentum equation for empty space. For non empty space we obtain a generalized Einstein equation, relating the Einstein tensor to a geometric s

Pedro F. Gonzalez-Diaz

A link between the possibility of extending a geodessically incomplete kinked spacetime to a spacetime which is geodesically complete and the energy conditions is discussed for the case of a cylindrically-symmetric spacetime kink. It is concluded that neither the strong nor the weak energy condition can be satisfied in the four-dimensional example, though th

Michael B. Mensky, Igor D. Novikov

Non-relativistic quantum theory of non-interacting particles in the spacetime containing a region with closed time-like curves (time-machine spacetime) is considered with the help of the path-integral technique. It is argued that, in certain conditions, a sort of superselection may exist for evolution of a particle in such a spacetime. All types of evolution

Jacob D. Bekenstein

The holographic bound that the entropy (log of number of quantum states) of a system is bounded from above by a quarter of the area of a circumscribing surface measured in Planck areas is widely regarded a desideratum of any fundamental theory, but some exceptions occur. By suitable black hole gedanken experiments I show that the bound follows from the gener

Victor Kromer

A model of rank polysemantic distribution with a minimal number of fitting parameters is offered. In an ideal case a parameter-free description of the dependence on the basis of one or several immediate features of the distribution is possible.

R. Moessner, S. L. Sondhi

We study the quantum dimer model on the triangular lattice, which is expected to describe the singlet dynamics of frustrated Heisenberg models in phases where valence bond configurations dominate their physics. We find, in contrast to the square lattice, that there is a truly short ranged resonating valence bond (RVB) phase with no gapless collective excitat

P. V. Parimi, H. Srikanth, M. Bailleul, S. Sridhar

A sensitive tunnel diode oscillator (TDO) operating at 4MHz is used to probe the dynamic response of La_{1-x}Sr_{x}MnO_{3} single crystals for x=0.125,0.175,0.28 and 0.33 doping. Systematics of the measured change in reactance as a function of temperature (30K<T<320K) and DC magnetic field (0<H<6kOe) reveal distinct temperature and field scales associated wi

C. Reichhardt, C. J. Olson, Franco Nori

We examine the dynamics of driven classical Wigner solids interacting with quenched disorder from charged impurities. For strong disorder, the initial motion is plastic -- in the form of crossing winding channels. For increasing drive, the disordered Wigner glass can reorder to a moving Wigner smectic -- with the electrons moving in non-crossing 1D channels.

A. Alan Middleton

Methods for studying droplets in models with quenched disorder are critically examined. Low energy excitations in two dimensional models are investigated by finding minimal energy interior excitations and by computing the effect of bulk perturbations. The numerical data support the assumptions of compact droplets and a single exponent for droplet energy scal

S. Somu, A. Widom, Y. N. Srivastava

In a gauge invariant formulation of the molecular electric dipole-photon interaction, the rigorous coupling is strictly linear in the photon creation and photon annihilation operators. The linear coupling allows for a super-radiant phase transition as in the Hepp-Lieb formulation. A previous notion of a quadratic-coupling ``no-go theorem&#39;&#39; for super-

J. F. Palierne

The transient network model of Green-Tobolsky [1946], Yamamoto [1956] and Tanaka-Edwards [1992] is formulated within the frame of thermodynamics of irreversible processes, using as a fundamental quantity the chemical potential associated to the connection of strands to the network and treating these connections as chemical-like reactions. All thermodynamic q

M. Ebrahim Fouladvand, Masoud Nematollahi, Farzad Zolfaghari

We propose a model for the intersection of two urban streets. The traffic status of the crossroads is controlled by a set of traffic lights which periodically switch to red and green with a total period of T. Two different types of crossroads are discussed. The first one describes the intersection of two one-way streets, while the second type models the inte

Hans-Karl Janssen

In a recent paper, de Freitas et al. [Phys. Rev. E 61, 6330 (2000)] presented simulational results for the critical exponents of the two-species reaction-diffusion system A + B -> 2B and B -> A in dimension d = 1. In particular, the correlation length exponent was found as ν= 2.21(5) in contradiction to the exact relation ν= 2/d. In this Comment, the symmetr

V. M. Loktev, V. M. Turkowski

The fermion Green function and spectral characteristics for the 2D Frohlich model of superconductivity at static fluctuations in the phase of the order parameter are calculated. The results demonstrate strongly non-Fermi-liquid properties of the system at finite temperatures and relate with the pseudogap behavior of high-$T_{c}$ superconductors at relatively

E. Rozenberg, M. Auslender, I. Felner, G. Gorodetsky

Measurements of magnetoresistance and magnetization were carried out on ceramic samples of La_{0.5}Pb_{0.5}MnO_{3} and La_{0.5}Pb_{0.5}MnO_{3}, containing 10 at. % Ag in a dispersed form. The results obtained for the resistivity at zero applied magnetic field exhibit a shallow minimum at temperatures T about 25 K - 30 K, which shifts towards lower temperatur

Ferdinando Mancini, Volodymyr Turkowski

The two-layer Hubbard model is studied by using the composite operator method. Magnetic properties of the model in the normal state are analyzed by studying the uniform static spin magnetic susceptibility as a function of doping and temperature. The relevance of the model to describe the physical behavior of two-layered cuprate high-$T_{c}$ superconductors i

A. V. Sologubenko, E. Felder, K. Gianno, H. R. Ott

We report measurements of the specific heat and the thermal conductivity of the model Heisenberg spin-1/2 chain cuprate Sr$_{2}$CuO$_{3}$ at low temperatures. In addition to a nearly isotropic phonon heat transport, we find a quasi one-dimensional excess thermal conductivity along the chain direction, most likely associated with spin excitations (spinons). T

M. Mueller, E. V. Albano, K. Binder

We study the phase behavior of a symmetric binary polymer blend which is confined into a thin film. The film surfaces interact with the monomers via short range potentials. We calculate the phase behavior within the self-consistent field theory of Gaussian chains. Over a wide range of parameters we find strong first order wetting transitions for the semi-inf

M. Mueller, K. Binder, E. V. Albano

Within self-consistent field theory we study the phase behavior of a symmetrical binary AB polymer blend confined into a thin film. The film surfaces interact with the monomers via short range potentials. One surface attracts the A component and the corresponding semi-infinite system exhibits a first order wetting transition. The surface interaction of the o

Maxim Makeev, Rodolfo Cuerno, Albert-László Barabási

We derive a stochastic nonlinear continuum theory to describe the morphological evolution of amorphous surfaces eroded by ion bombardment. Starting from Sigmund&#39;s theory of sputter erosion, we calculate the coefficients appearing in the continuum equation in terms of the physical parameters characterizing the sputtering process. We analyze the morphologi

G. Reents, R. Metzler, W. Kinzel

We present a variant of the Minority Game in which players who where successful in the previous timestep stay with their decision, while the losers change their decision with a probability $p$. Analytical results for different regimes of $p$ and the number of players $N$ are given and connections to existing models are discussed. It is shown that for $p \pro

J. A. G. Orza, R. Brito, M. H. Ernst

Replacement of cond-mat/0002383. Re-analysis of computer simulations, new figures and modification of conclusions.

Donovan L. Domingue, William C. Keel, Raymond E. White

We use slit spectroscopy of overlapping pairs of galaxies to directly determine the extinction in disks of foreground spiral galaxies. The Doppler shifts of pair members are determined via cross-correlation and their relative correlation amplitudes are used to separate their contributions to the combined spectra in regions of overlap. This spectroscopic appr

Martin Bucher, Kavilan Moodley, Neil Turok

The most general homogeneous and isotropic statistical ensemble of linear scalar perturbations which are regular at early times, in a universe with only photons, baryons, neutrinos, and a cold dark matter (CDM) component, is described by a 5x5 symmetric matrix-valued generalization of the power spectrum. This description is complete if the perturbations are