May 2001 arXiv papers — page 3

C. Giunti

Subtle problems in the theory of neutrino oscillations in vacuum are discussed. It is shown that Lorentz invariance implies that in general flavor neutrinos in oscillation experiments are superpositions of massive neutrinos with different energies and different momenta. It is argued that a wave packet description of massive neutrinos is necessary in order to

D. V. Shirkov

Here, we report briefly two topics: 1) The latest version of ``Analytic Perturbation Theory" (APT) devised recently for the QCD observables both in the Euclidean and Minkowskian regions. 2) Results of the APT--based calculation for some physical processes.

V. I. Kashkan, V. I. Kuvshinov, R. G. Shulyakovsky

Instanton-induced deep-inelastic processes are considered. Unlike previous results we calculate nonzero quark modes contribution.

A. Hebecker

After recalling why dynamical adjustment mechanisms represent a particularly attractive possibility for solving the cosmological constant problem, we briefly discuss their intrinsic difficulties as summarized in Weinberg's no-go theorem. We then comment on some problems of the recently proposed `self-tuning' mechanism in 4+1 dimensions. Finally, we d

R. G. Shulyakovsky

We consider instanton-induced high energy processes in an electroweak-type model. Multi-fermion final states are taken into account in Gauss approximation. Unlike previous results we calculate nonzero fermion modes contribution to cross-section by straightforward procedure. This contribution can be important at energies of sphaleron mass order.

F. Guerin

The Keldysh three- and four-point functions are related to analytical continuations of the Imaginary Time amplitudes,in momentum space. The relation provides an interesting interpretation of the amplitudes that are specific to the Keldysh basis, and of the Ward Identities they satisfy in QED. The interpretation carries over to the (perturbative) non-equilibr

U. Aglietti

We present a new sum rule which does not contain any Landau-pole effect and allows a determination of Vub/Vcb with a theoretical error of O(5%).

D. Bakari, Y. Becherini, M. Spurio

Upward throughgoing muons in underground detectors are induced by atmospheric $ν_μ$ with energies in the $1-10^4 GeV$ range. The oscillations of atmospheric muon neutrinos should affect mainly those with energy smaller than $E_ν\sim 50 GeV$, or $E_μ\le 10 GeV$ . We analyzed the MACRO upward throughgoing muons data set, using the Multiple Coulomb Scattering t

A. Gritsan, . CLEO Collaboration

We report on a search for the decay B+ -> D*+ K0_S and its charge conjugate with the CLEO detector at the Cornell Electron Storage Ring (CESR). No candidates are found in 9.10/fb of data. The background is estimated to be 0.29 +- 0.05 leading to an upper limit BF(B+ -> D*+ K0_S) = 9.5 x 10^{-5} (90% C.L.).

Kayll Lake

We present a streamlined calculation of the Kretschmann scalar for 5D Vacua considered recently by Fukui et al. (gr-qc/0105112).

Nathalie Deruelle, Tomas Dolezel

In the literature about the Randall-Sundrum scenario one finds on one hand that there exist (small) corrections to Newton's law of gravity on the brane, and on another that the exact (and henceforth linearized) Einstein equations can be recovered on the brane. The explanation for these seemingly contradictory results is that the behaviour of the bulk far

Matthew Parry, Richard Easther

We investigated the possibility that nonlinear gravitational effects influence the preheating era after inflation, using numerical solutions of the inhomogeneous Einstein field equations. We compared our results to perturbative calculations and to solutions of the nonlinear field equations in a rigid (unperturbed) spacetime, in order to isolate gravitational

Donald Marolf

This is a brief summary of lectures given at the Fourth Mexican School on Gravitation and Mathematical Physics. The lectures gave an introduction to branes in eleven-dimensional supergravity and in type IIA supergravities in ten-dimensions. Charge conservation and the role of the so-called `Chern-Simons terms' were emphasized. Known exact solutions were

C. Csaki, J. Erlich, C. Grojean

Brane worlds are theories with extra spatial dimensions in which ordinary matter is localized on a (3+1) dimensional submanifold. Such theories could have interesting consequences for particle physics and gravitational physics. In this essay we concentrate on the cosmological constant (CC) problem in the context of brane worlds. We show how extra-dimensional

Victor Kromer

It is offered to consider word meanings changes in diachrony as semicontinuous random walk with reflecting and swallowing screens. The basic characteristics of word life cycle are defined. Verification of the model has been realized on the data of Russian words distribution on various age periods.

T. Antal, M. Droz, G. Gyorgyi, Z. Racz

We study the finite-size scaling of the roughness of signals in systems displaying Gaussian 1/f power spectra. It is found that one of the extreme value distributions (Gumbel distribution) emerges as the scaling function when the boundary conditions are periodic. We provide a realistic example of periodic 1/f noise, and demonstrate by simulations that the Gu

C. K. Lo, K. W. Yu

We have computed the local electric field in a body-centered tetragonal (BCT) lattice of point dipoles via the Ewald-Kornfeld formulation, in an attempt to examine the effects of a structure transformation on the local field strength. For the ground state of an electrorheological solid of hard spheres, we identified a novel structure transformation from the

R. T. Clay, S. Mazumdar

Comment on Phys. Rev. Lett. 86, 2086 (2001)

R. J. McQueeney, T. Egami, J. -H. Chung, Y. Petrov

Inelastic neutron scattering data from a twinned single-crystal of YBa2Cu3O6.95 are presented that show a distinct a-b plane anisotropy in the oxygen vibrations. The Cu-O bond-stretching type phonons are simultaneously observed along the a and b directions due to a 4 meV splitting arising from the orthorhombicity. The present results show the bond-stretching

Mikko Alava, Miguel A. Munoz

According to recent numerical results from lattice models, the critical exponents of systems with many absorbing states and an order parameter coupled to a non-diffusive conserved field coincide with those of the linear interface depinning model within computational accuracy. In this paper the connection between absorbing state phase transitions and interfac

N. Freytag, Y. Tokunaga, M. Horvatic, C. Berthier

The average electron spin-polarization $\cal P$ of two-dimensional electron gas confined in $\rm GaAs/GaAlAs$ multiple quantum-wells was measured by nuclear magnetic resonance (NMR) near the fractional quantum Hall state with filling factor $ν={2/3}$. Above this filling factor (${2/3} \leq ν< 0.85$), a strong depolarization is observed corresponding to two s

M. M. Kettenis, L. G. Suttorp

Equilibrium quantum statistical methods are used to study the pair correlation function for a magnetized free-electron gas in the presence of a hard wall that is parallel to the field. With the help of a path-integral technique and a Green function representation the modifications in the correlation function caused by the wall are determined both for a non-d

T. Winiecki, C. S. Adams

The dynamics of vortices in a type-II superconductor with defects are studied by solving the time-dependent Ginzburg-Landau equations in two and three dimensions. We show that vortex flux tubes are trapped by volume defects up to a critical current density where they begin to jump between pinning sites along static flow channels. We study the dependence of t

Fei Ye, Guo-Hui Ding, Bo-Wei Xu

In the present paper, we proposed a simple spin-1/2 model which provides a exactly solvable example to study the Ising criticality with central charge c=1/2. By mapping it onto the real Majorana fermions, the Ising critical behavior is explored explicitly, although its bosonized form is not the double frequency sine-Gordon model.

W. Selke, M. Pleimling, I. Peschel, M. Kaulke

Properties of magnetic films are studied in the framework of Ising models. In particular, we discuss critical phenomena of ferromagnetic Ising films with straight lines of magnetic adatoms and straight steps on the surface as well as phase diagrams of the axial next-nearest neighbour Ising (ANNNI) model for thin films exhibiting various spatially modulated p

Joachim Brand, William P. Reinhardt

The connection between quantized vortices and dark solitons in a long and thin, waveguide-like trap geometry is explored in the framework of the non-linear Schrödinger equation. Variation of the transverse confinement leads from the quasi-1D regime where solitons are stable to 2D (or 3D) confinement where soliton stripes are subject to a transverse modulatio

Jian-Xin Zhu, Wonkee Kim, C. S. Ting, J. P. Carbotte

Recently Chakravarty {\em et al.} proposed an ordered $d$-density wave (DDW) state as an explanation of the pseudogap phase in underdoped high-temperature cuprates. We study the competition between the DDW and superconducting ordering based on an effective mean-field Hamiltonian. We are mainly concerned with the effect of the DDW ordering on the electronic s

V. F. Cardone, R. de Ritis, A. A. Marino

We investigate the dark halo lens mass function (MF) for a wide class of spheroidal non singular isothermal models comparing observed and observable microlensing quantities for MACHO observations towards LMC and taking into account the detection efficiency. We evaluate the microlensing observable quantities, i.e. observable optical depth, number of events an

A. Muecke, R. J. Protheroe

The Synchrotron Proton Blazar model is a promising model to explain high energy emission from gamma-ray loud BL Lac objects like Mkn 421. In contrast to leptonic models, the hadronic explanation of gamma-ray emission predicts ultrahigh energy neutrinos. The predicted neutrino spectra from a typical High-energy cutoff BL Lac Object (HBL) and a Low-energy cuto

L. M. Rebull, S. C. Wolff, S. E. Strom, R. B. Makidon

We examine the early angular momentum history of stars in young clusters via 197 photometric periods in the Orion Flanking Fields, 83 photometric periods in NGC 2264, and 256 measurements of v sin i in the ONC. We show that PMS stars, even those without observable disks, apparently do not conserve stellar angular momentum as they evolve down their convective

Q. Daniel Wang, Stefan Immler, Rene Walterbos, James T. Lauroesch

We present a Chandra X-ray observation that shows, unambiguously for the first time, the presence of a giant diffuse X-ray-emitting corona around the edge-on disk galaxy NGC 4631. This corona, with a characteristic thermal temperature of 2-7\times10^6 K, extends as far as 8 kpc away from the galactic plane. The X-ray morphology resembles the radio halo of th

C. R. Canizares, T. E. Jeltema, T. Fang, M. W. Bautz

We observed MS 1054-0321, the highest redshift cluster of galaxies in the Einstein Medium Sensitivity Survey (EMSS), with the Chandra ACIS-S detector. We find the X-ray temperature of the cluster to be 10.4^{+1.7}_{-1.5} keV, slightly lower than that inferred previously and in agreement with the observed velocity dispersion and that found from weak lensing.

Michael G. Hauser, Eli Dwek

The cosmic infrared background records much of the radiant energy released by processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In the past few years, data from the Cosmic Background Explorer mission provided the first measurements of this background, with additional constraints coming fr

T. Storchi-Bergmann, R. M Gonzalez Delgado, H. R. Schmitt, R. Cid Fernandes

We investigate the relation between the characteristics of the circumnuclear stellar population and both the galaxy morphology and the presence of close companions for a sample of 35 Seyfert 2 nuclei. Fifteen galaxies present unambiguous signatures of recent episodes of star formation within $\approx$300 pc from the nucleus. When we relate this property with

Yangsen Yao, Shuang Nan Zhang, Xiaoling Zhang

Understanding the properties of the hot corona is very important for studying the accretion disks in black hole X-ray binary systems. Using the Monte-Carlo technique to simulate the inverse Compton scattering process between disk photons and electrons in the hot corona, we have produced two table models in the XSPEC package. Applying the models to the broad-

R. C. Dohm-Palmer, A. Helmi, H. Morrison, M. Mateo

As part of the Spaghetti Project Survey (SPS) we have detected a concentration of giant stars well above expectations for a smooth halo model. The position (l~350, b~50) and distance (~50 kpc) of this concentration match those of the Northern over-density detected by SDSS (Yanny et al. 2000, Ivezic et al. 2000). We find additional evidence for structure at ~

M. R. Blanton, R. H. Lupton, F. Miller Maley, N. Young

The Sloan Digital Sky Survey (SDSS) will observe around 10^6 spectra from targets distributed over an area of about 10,000 square degrees, using a multi-object fiber spectrograph which can simultaneously observe 640 objects in a circular field-of-view (referred to as a ``tile&#39;&#39;) 1.49 degrees in radius. No two fibers can be placed closer than 55&#39;&

Robert A. Benjamin, Bradford A. Benson, Donald P. Cox

Radiative cooling is an important ingredient in hydrodynamical models involving evolution of high temperature plasmas. Unfortunately, calculating an accurate cooling coefficient generally requires the solution of over a hundred differential equations to follow the ionization. We discuss here a simple 2-parameter approximation for the cooling coefficient due

Abhas Mitra

There are many observational evidences for the detection of compact objects with masses significantly larger (in galactic cases) or much larger (in extragalactic cases) than the upper limits of masses of em cold Neutron Stars. Such compact objects are commonly interpreted as Black Holes (BHs). However, we point out that while such Black Hole Candidates (BHCs

S. Fegan, The VERITAS collaboration

Observations of unidentified EGRET sources were made with the Whipple 10m imaging atmospheric Cherenkov telescope between Fall 1999 and Spring 2001. During this period, a high resolution 490 pixel camera with 4 degree field of view was present on the telescope. Characterization of the off-axis response of this instrument was done using observations of the Cr

J. Palous, S. Ehlerova

The star formation triggered in dense walls of expanding shells will be discussed. The fragmentation process is studied using the linear and non-linear perturbation theory. The influence of the energy input, the ISM distribution and the speed of sound is examined analytically and by numerical simulations. We formulate the condition for the gravitational frag

Jonathan E. Grindlay, Craig Heinke, Peter D. Edmonds, Stephen S. Murray

We have obtained high resolution (<1&#34;) deep x-ray images of the globular cluster 47Tucanae (NGC 104) with the Chandra X-ray Observatory to study the population of compact binaries in the high stellar density core. A 70 kilosec exposure of the cluster reveals a centrally concentrated population of faint (Lx ~10^{30-33} erg/s) x-ray sources, with at least

Kohji Tomisaka

Collapse of the rotating magnetized molecular cloud core is studied with the axisymmetric magnetohydrodynamical (MHD) simulations. Due to the change of the equation of state of the interstellar gas, the molecular cloud cores experience several different phases as collapse proce eds. In the isothermal run-away collapse ($n \lesssim 10^{10}{\rm H_2 cm}^{-3}$),

T. Oka, S. Yamamoto, M. Iwata, H. Maezawa

We present observations of the 3P1-3P0 fine structure transition of atomic carbon [CI], the J=3-2 transition of CO, as well as of the J=1-0 transitions of 13CO and C18O toward DR15, an HII region associated with two mid-infrared dark clouds (IRDCs). The 13CO and C18O J=1-0 emissions closely follow the dark patches seen in optical wavelength, showing two self

A. Comastri, F. Fiore, C. Vignali, G. Matt

The BeppoSAX High Energy Large Area Survey (HELLAS) has surveyed several tens of square degrees of the sky in the 5--10 keV band down to a flux of about 5 10^-14 erg cm-2 s-1. The extrapolation of the HELLAS logN--logS towards fainter fluxes with an euclidean slope is consistent with the first XMM measurements, in the same energy band, which are a factor 20

F. Fiore, P. Giommi, C. Vignali, A. Comastri

The BeppoSAX High Energy Large Area Survey (HELLAS) has surveyed about 85 deg^2 of sky in the 5-10 keV band down to a flux of 4-5 10^-14 erg cm-2 s-1. The source surface density of 16.9+-6.4 deg$^{-2}$ at the survey limit corresponds to a resolved fraction of the 5-10 keV X-ray background (XRB) of the order of 20-30 %. Hardness ratios analysis indicates that

L. Derome, M. Buenerd

The possible sources of light nuclei populations observed recently below the geomagnetic cutoff by the AMS experiment are discussed in terms of nuclear processes: fragmentation of the incoming flux of cosmic helium on atmospheric nuclei, and nuclear coalescence from proton and helium induced reactions. Results of simulations for deuterium, tritium, helium 3

Manolis Plionis

Using the APM cluster data we investigate whether the dynamical status of clusters is related to the large-scale structure of the Universe. We find that cluster substructure is strongly correlated with the tendency of clusters to be aligned with their nearest neighbour and in general with the nearby clusters that belong to the same supercluster. Furthermore,

E. Massaro, F. Mantovani, R. Fanti, R. Nesci

Recent radio images of the BL Lac object ON231 (W Com, 1219+285) show remarkable new features in the source structure compared to those previously published. The images were obtained from observations made with the European VLBI Network plus MERLIN at 1.6 GHz and 5 GHz after the exceptional optical outburst occurred in Spring 1998. The up-to-date B band hist

R. Sadat, A. Blanchard

The baryon fraction in galaxy clusters is one of the most direct way to constrain $\omo$. The baryonic fraction is estimated to be in the range fb = (0.15 - 0 .20) h^{-3/2} which is several times higher than expected from the observed light element abundances in $\omo=1$ universe, leading to the conclusion that we live in low density universe. In this work I

Naoki Itoh, Youhei Kawana, Satoshi Nozawa, Yasuharu Kohyama

We extend the formalism for the calculation of the relativistic corrections to the Sunyaev-Zel&#39;dovich effect for clusters of galaxies and include the multiple scattering effects in the isotropic approximation. We present the results of the calculations by the Fokker-Planck expansion method as well as by the direct numerical integration of the collision t

Jerome A. Orosz, John R. Thorstensen, R. Kent Honeycutt

We present extensive spectroscopy and photometry of the dwarf nova V630 Cassiopeiae. A late-type (K4-5) absorption spectrum is easily detectable, from which we derive the orbital parameters. We find a spectroscopic period of P=2.56387 +/- (4 times 10^{-5}) days and a semiamplitude of K_2=132.9 +/- 4.0 km/s. The resulting mass function, which is a firm lower

Y. Lu, K. S. Cheng, L. C. Deng

A possible relation between the high dispersion in metallicity of metal-poor halo stars and the minor merger processes in the history of the Galaxy is presented. The foreign populations of stars in the satellites through minor merger processes, make considerable contributions to the Galactic halo, therefore alter the intrinsic distribution of metallicities o

Chang Won Lee, Philip C. Myers, Mario Tafalla

We present the results of an extensive mapping survey of 53 `starless&#39; cores in the optically thick line of CS 2-1 and the optically thin lines of N2H+ 1-0 and C18O 1-0. The purpose of this survey was to search for signatures of extended inward motions. This study finds 10 `strong&#39; and 9 `probable&#39; infall candidates, based on $δV_{CS}$ analysis a

Eric I. Barnes

In an effort to more fully understand the variety of stellar distribution functions that can be used to construct models of realistic galaxies, the correlation integral method for orbit characterization that previously has been introduced by Grassberger & Procaccia (1983) and Carnevali & Santangelo (1984) is examined in considerable detail. The broad utility

Josef Koller, Stefan Kimeswenger

We present a new model to explain the excess in mid and near infrared emission of the central, hydrogen poor dust knot in the planetary nebula (PN) Abell 58. Current models disagree with ISO measurement because they apply an average grain size and equilibrium conditions only. We investigate grain size distributions and temperature fluctuations affecting infr

Z. Ivezic, S. Tabachnik, R. Rafikov, R. H. Lupton

We discuss measurements of the properties of about 10,000 asteroids detected in 500 deg2 of sky in the Sloan Digital Sky Survey (SDSS) commissioning data. The moving objects are detected in the magnitude range 14 < r < 21.5, with a baseline of 5 minutes. Extensive tests show that the sample is at least 98% complete, with the contamination rate of less than 3

Yasushi Fukazawa, Naoko Iyomoto, Aya Kubota, Yukari Matsumoto

We observed the nearby galaxy M~51 (NGC 5194) with BeppoSAX. The X-ray properties of the nucleus below 10 keV are almost the same as the ASCA results regarding the hard component and the neutral Fe K$α$ line, but the intensity is about half of the ASCA 1993 data. Beyond this, in the BeppoSAX PDS data, we detected a bright hard X-ray emission component which

R. Sagar, C. S. Stalin, D. Bhattacharya, S. B. Pandey

We report photometric observations of the optical afterglow of GRB010222 in V,R and I passbands carried out at UPSO, Naini Tal between 22-27 Feb 2001. We determine CCD Johnson BV and Cousins RI photometric magnitudes for 31 stars in the field of GRB010222 and use them to calibrate our measurements as well as other published BVRI photometric magnitudes of GRB

Donald Marolf, Pedro J. Silva

The presence of a distant D4-brane is used to further investigate the duality between M-theory and D0-brane quantum mechanics. Although the D4-brane background fields are not strong enough to induce a classical dielectric effect in the D0 system, a polarization of the quantum mechanical ground state does result. A similar deformation arises for the bubble of

Francisco A. Brito, Dionisio Bazeia

We explore the idea of a network of domain walls to appear at the surface of a soliton star. We show that for a suitable fine tuning among the parameters of the model we can find localized fermion zero modes only on the network of domain walls. In this scenario the soliton star gets unstable and decays into free particles before the cold matter upper mass li

Jiunn-Wei Chen, Xiangdong Ji

In a world with two quark flavors and a large number of colors (N_c), the polarized and unpolarized quark distributions in the delta are completely determined by those in the nucleon up to {\cal O}(1/N_c). In particular, we find q_Δ(x) =[(1\pm 2T_z)u_N(x)+ (1\mp 2T_z)d_N(x)]/2 and Δq_Δ(x) =[(5\pm 2T_z)Δu_N(x) + (5\mp 2T_z)Δd_N(x)]/10, where q = u, d and $T_z

Andrew Mack, Tina Kahniashvili, Arthur Kosowsky

A stochastic magnetic field in the early Universe will produce anisotropies in the temperature and polarization of the cosmic microwave background. We derive analytic expressions for the microwave background temperature and polarization power spectra induced by vector and tensor perturbations from a power-law magnetic field. For a scale-invariant stochastic

J. Berges

We compute the nonequilibrium real-time evolution of an O(N)-symmetric scalar quantum field theory from a systematic 1/N expansion of the 2PI effective action to next-to-leading order, which includes scattering and memory effects. In contrast to the standard 1/N expansion of the 1PI effective action, the next-to-leading order expansion in presence of a possi

Carl L. Gardner

A semiclassical gravitation model is outlined which makes use of the Casimir energy density of vacuum fluctuations in extra compactified dimensions to produce the present-day cosmological constant as rho_LAMBDA ~ M^8/M_P^4, where M_P is the Planck scale and M is the weak interaction scale. The model is based on (4+D)-dimensional gravity, with D = 2 extra dim

M. Stiavelli, C. Scarlata, N. Panagia, T. Treu

We have carried out a search for Lyman alpha emission from galaxies at z~=2.4 over a field of 1200 sq. arcmin using the CFH12K camera at the CFHT and a custom medium band filter. The search has uncovered 58 candidates, corresponding to a completeness-corrected source density of ~0.07 sq. arcmin^-2. Our sources have red colors (B-I~=1.8) which imply either th

E. Capelas de Oliveira, W. A. Rodrigues

We exhibit exact finite energy superluminal solutions of Maxwell equations in vacuum.

Jun-Ho Jeong, Nigel Goldenfeld, Jonathan A. Dantzig

We study the effect of fluid flow on three-dimensional (3D) dendrite growth using a phase-field model on an adaptive finite element grid. In order to simulate 3D fluid flow, we use an averaging method for the flow problem coupled to the phase-field method and the Semi-Implicit Approximated Projection Method (SIAPM). We describe a parallel implementation for

Rodolfo Gambini, Rafael A. Porto

Up to now it has been impossible to find a realistic interpretation for the reduction process in relativistic quantum mechanics. The basic problem is the dependence of the states on the frame within which collapse takes place. A suitable use of the causal structure of the devices involved in the measurement process allows us to introduce a covariant notion f

Michael Gronau, David London, Nita Sinha, Rahul Sinha

In the presence of penguin contributions, the indirect CP asymmetry in B0(t) -> pi+ pi- measures sin(2α+ 2θ), where 2θparametrizes the size of the penguin ``pollution.&#39;&#39; We derive a new upper bound on |2θ|, requiring the measurement of of BR(B+ -> pi+ pi0) and an upper bound on B00 \equiv {1\over 2} [BR(B0 -> pi0 pi0) + BR(B0bar -> pi0 pi0)]. The new

Jørgen Rasmussen, Mark A. Walton

Three-point functions of Wess-Zumino-Witten models are investigated. In particular, we study the level-dependence of three-point functions in the models based on algebras $su(3)$ and $su(4)$. We find a correspondence with Berenstein-Zelevinsky triangles. Using previous work connecting those triangles to the fusion multiplicities, and the Gepner-Witten depth

P. Norberg, C. M. Baugh, E. Hawkins, S. Maddox

We investigate the dependence of the strength of galaxy clustering on intrinsic luminosity using the Anglo-Australian two degree field galaxy redshift survey (2dFGRS). The 2dFGRS is over an order of magnitude larger than previous redshift surveys used to address this issue. We measure the projected two-point correlation function of galaxies in a series of vo

V. Yu. Irkhin, A. A. Katanin

We consider the two-dimensional t-t&#39; Hubbard model with the Fermi level being close to the van Hove singularities. The phase diagram of the model is discussed. In a broad energy region the self-energy at the singularity points has a nearly-linear energy dependence. The corresponding correction to the density of states is proportional to ln^3(e). Both rea

Michael T. Anderson

This paper considers the existence of conformally compact Einstein metrics on 4-manifolds. A reasonably complete understanding is obtained for the existence of such metrics with prescribed conformal infinity, when the conformal infinity is of positive scalar curvature. We find in particular that general solvability in this class depends on the topology of th

Jose F. Nieves, Palash B. Pal

We analyze the dependence of the squared amplitudes on the rephasing-invariant CP-violating parameters of the lepton sector, involving Majorana neutrinos, for various lepton-conserving and lepton-violating processes. We analyze the conditions under which the CP-violating effects in such processes vanish, in terms of the minimal set of rephasing invariants, g

Wolfgang Ebeling, Sabir M. Gusein-Zade

There are some generalizations of the classical Eisenbud-Levine-Khimshashvili formula for the index of a singular point of an analytic vector field on $R^n$ for vector fields on singular varieties. We offer an alternative approach based on the study of indices of 1-forms instead of vector fields. When the variety under consideration is a real isolated comple

G. Barenboim, F. J. Botella, O. Vives

In this work, we update the constraints on tree level FCNC couplings in the framework of a theory with n isosinglet vector-like down quarks. In this context, we emphasize the sensitivity of the B -> J/psi K_S CP asymmetry to the presence of new vector-like down quarks. This CP asymmetry, together with the rare decays B -> X_{s,d} l bar{l} and K -> pi nu bar{

B. de Wit, A. Marshakov

We consider the associativity (or WDVV) equations in the form they appear in Seiberg-Witten theory and prove that they are covariant under generic electric-magnetic duality transformations. We discuss the consequences of this covariance from various perspectives.

J. N. Ginocchio, A. Leviatan

Using the fact that pseudospin is an approximate symmetry of the Dirac Hamiltonian with realistic scalar and vector mean fields, we derive the wave functions of the pseudospin partners of eigenstates of a realistic Dirac Hamiltonian and compare these wave functions with the wave functions of the Dirac eigenstates.

F. Jegerlehner, M. Yu. Kalmykov, O. Veretin

The relationship between MS and pole masses of the vector bosons Z and W is calculated at the two-loop level in the Standard Model. We only consider the purely bosonic contributions which represents a gauge invariant subclass of diagrams. All calculations were performed in the linear $R_ξ$ gauge with three arbitrary gauge parameters utilizing the method of a

D. S. Berman, P. Sundell

We describe properties of the M-theory five-brane containing $Q$ coincident self-dual strings on its worldvolume. This is the five-brane description of Q membranes ending on the five-brane. In particular, we consider a Maldacena-like low energy limit in the six-dimensional worldvolume which yields a near `horizon&#39; description of the self-dual string usin

A. Ali, A. Ya. Parkhomenko

We calculate the so-called hard spectator corrections in ${\cal O} (α_s)$ in the leading-twist approximation to the decay widths for $B \to K^{*} γ$ and $B \to ργ$ decays and their charge conjugates, using the Large Energy Effective Theory (LEET) techniques. Combined with the hard vertex and annihilation contributions, they are used to compute the branching

R. D&#39;Hulst, G. J. Rodgers

We show that a cut-and-paste model to mimic a trial-and-error process of adaptation displays two pairs of percolation and depinning transitions, one for persistence and the other for efficiency. The percolation transition signals the onset of a property and the depinning transition, the growth of the same property. Despite its simplicity, the cut-and-paste m

Mark Auslender, Eugene Kogan

We study ferromagnetic transition in three-dimensional double-exchange model containing impurities. The influence of both spin fluctuations and impurity potential on conduction electrons is described in coherent potential approximation. In the framework of thermodynamic approach we construct Landau functional for the system &#34;electrons (in disordered envi

Noriaki Ikeda

We consider a deformation of the BF theory in any dimension by means of the antifield BRST formalism. Possible consistent interaction terms for the action and the gauge symmetries are analyzed and we find a new class of topological gauge theories. Deformations of the world volume BF theory are considered as possible deformations of the topological open membr

Fumihiko Sugino

In this paper, we consider a reduced supersymmetric Yang-Mills integral with four supercharges by using a Gaussian approximation scheme and its improved version. We calculate the free energy and the expectation values of Polyakov loop and Wilson loop operators by extending the method employed in the bosonic case in the previous paper. Our results nicely matc

Kazuo Hosomichi, Yuji Satoh

In the conformal field theories having affine SL(2) symmetry, we study the operator product expansion (OPE) involving primary fields in highest weight representations. For this purpose, we analyze properties of primary fields with definite SL(2) weights, and calculate their two- and three-point functions. Using these correlators, we show that the correct OPE

S. Lee, H. Mori, T. Masui, Yu. Eltsev

Here we report the growth of sub-millimeter MgB2 single crystals of various shapes under high pressure in Mg-B-N system. Structure refinement using a single-crystal X-ray diffraction analysis gives lattice parameters a=3.0851(5) A and c=3.5201(5) A with small reliability factors (Rw =0.025, R=0.018), which enables us to analyze the Fourier and Fourier differ

J. T. Lunardi

We address the question about the velocity of signals carried by Bessel beams wave packets propagating in vacuum and having well defined wavefronts in time. We find that this problem is analogous to that of propagation of usual plane wave packets within dispersive media and conclude that the signal velocity can not be superluminal.

Theodore Voronov

We define \textit{graded manifolds} as a version of supermanifolds endowed with an additional $\mathbb Z$-grading in the structure sheaf, called \textit{weight} (not linked with parity). Examples are ordinary supermanifolds, vector bundles over supermanifolds, double vector bundles, iterated constructions like $TTM$, etc. I give a construction of \textit{dou

Mang Feng

The complete solutions of the Schrödinger equation for a particle with time-dependent mass moving in a time-dependent linear potential are presented. One solution is based on the wave function of the plane wave, and the other is with the form of the Airy function. A comparison is made between the present solution and former ones to show the completeness of t

D. Bonatsos, N. Karoussos, P. P. Raychev, R. P. Roussev

Quantum algebras (also called quantum groups) are deformed versions of the usual Lie algebras, to which they reduce when the deformation parameter q is set equal to unity. From the mathematical point of view they are Hopf algebras. Their use in physics became popular with the introduction of the q-deformed harmonic oscillator as a tool for providing a boson

R. Friedberg, T. D. Lee, W. Q. Zhao, A. Cimenser

We present a new convergent iterative solution for the two lowest quantum wave functions $ψ_{ev}$ and $ψ_{od}$ of the Hamiltonian with a quartic double well potential $V$ in one dimension. By starting from a trial function, which is by itself the exact lowest even or odd eigenstate of a different Hamiltonian with a modified potential $V+δV$, we construct the

Jie Liu, Li-Bin Fu, Bi-Yiao Ou, Shi-Gang Chen

A nonlinear Landau-Zener model was proposed recently to describe, among a number of applications, the nonadiabatic transition of a Bose-Einstein condensate between Bloch bands. Numerical analysis revealed a striking phenomenon that tunneling occurs even in the adiabatic limit as the nonlinear parameter $C$ is above a critical value equal to the gap $V$ of av

B. Georgeot, D. L. Shepelyansky

We show that certain computational algorithms can be simulated on a quantum computer with exponential efficiency and be insensitive to phase errors. Our explicit algorithm simulates accurately the classical chaotic dynamics for exponentially many orbits even when the quantum fidelity drops to zero. Such phase-insensitive algorithms open new possibilities for

S. E. Emelin, A. L. Pirozerski, E. F. Mikhailov, S. S. Vlasenko

New non-stationary non-contracted form of the erosive radially-slotted discharge as a thin round sheet with the current of the azimuth direction have been discovered, its existence beings stipulated by a radial transport-wave fluxes. Characteristic features of this discharge is self-confinement of the discharge current magnitude, corresponding decrease of th

Stuart Chester, Fabrice Charlette, Charles Meneveau

The dynamic model for large-eddy simulation (LES) of turbulent flows requires test filtering the resolved velocity fields in order to determine model coefficients. However, test filtering is costly to perform in large-eddy simulation of complex geometry flows, especially on unstructured grids. The objective of this work is to develop and test an approximate

G. Battistoni, M. Caccia, R. Campagnolo, C. Meroni

The performance of a large (3x3 $cm^2$) streamer tube cell in drift mode is shown. The detector space resolution has been studied using cosmic muons crossing an high precision silicon telescope. The experimental results are compared with a GARFIELD simulation.

D. Bonatsos, N. Karoussos, D. Lenis, P. P. Raychev

Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator with Uq(3)>SOq(3) symmetry are compared to experimental data for atomic clusters of alkali metals (Li, Na, K, Rb, Cs), noble metals (Cu, Ag, Au), divalent metals (Zn, Cd), and trivalent metals (Al, In), as well as to theoretical predictions of jellium models, Woods-Saxon and wine bottl

John Michael Williams

Short-baseline calculations reveal that if the neutrino were massive, it would show a beautifully structured difference spectrum; however, this spectrum seems beyond current experimental reach. An interval-timing paradigm would not seem feasible in a short-baseline experiment; however, interval timing on an Earth-Moon long baseline experiment might be able t