February 1999 arXiv papers — page 6

Charles D. Dermer, Markus Boettcher, J. Chiang

In the external shock model, gamma-ray burst (GRB) emissions are produced by the energization and deceleration of a thin relativistic blast wave due to its interactions with the circumburst medium (CBM). We study the physical properties of an analytic function which describes temporally-evolving GRB spectra in the limit of a smooth CBM with density n(x)\prop

S. Blinnikov

I argue that cosmic Gamma-ray Bursts (GRB) may be produced by collapses or mergers of stars made of `mirror' matter. The mirror neutrinos (which are sterile for our matter) produced at these events can oscillate into ordinary neutrinos. The annihilations or decays of the latter create an electron-positron plasma and subsequent relativistic fireball with

Izumi Hachisu, Mariko Kato, Ken'ichi Nomoto, Hideyuku Umeda

We have found a new evolutionary path to Type Ia supernovae (SNe Ia) which has been overlooked in previous work. In this scenario, a carbon-oxygen white dwarf (C+O WD) is originated, not from an asymptotic giant branch star with a C+O core, but from a red-giant star with a helium core of $\sim 0.8-2.0 M_\odot$. The helium star, which is formed after the firs

Zeferino Andrade, Richard H. Price

The gravitational radiation generated by a particle in a close unbounded orbit around a neutron star is computed as a means to study the importance of the $w$ modes of the neutron star. For simplicity, attention is restricted to odd parity (``axial'') modes which do not couple to the neutron star's fluid modes. We find that for realistic neutron

Joel S. Rozowsky, Charles B. Thorn

The Newtonian character of gauge theories on a light front requires that the longitudinal momentum P^+, which plays the role of Newtonian mass, be conserved. This requirement conflicts with the standard definition of the force between two sources in terms of the minimal energy of quantum gauge fields in the presence of a quark and anti-quark pinned to points

Richard Lieu, Massimiliano Bonamente, Jonathan P. D. Mittaz

Since all of the five clusters of galaxies observed by the Extreme Ultraviolet Explorer deep survey telescope are found to possess a diffuse EUV emitting component which is unrelated to the virial gas at X-ray temperatures, the question concerning the nature of this new component has been a subject of controversy. Here we present results of an EUV and soft X

J. S. Alcaniz, J. A. S. Lima

The ages of two old galaxies (53W091, 53W069) at high redshifts are used to constrain the value of the cosmological constant in a flat universe ($Λ$CDM) and the density parameter $Ω_M$ in Friedmann-Robertson-Walker (FRW) models with no $Λ$-term. In the case of $Λ$CDM models, the quoted galaxies yield two lower limits for the vacuum energy density parameter,

G. J. Galloway, K. Schleich, D. M. Witt, E. Woolgar

Motivated by recent interest in black holes whose asymptotic geometry approaches that of anti-de Sitter spacetime, we give a proof of topological censorship applicable to spacetimes with such asymptotic behavior. Employing a useful rephrasing of topological censorship as a property of homotopies of arbitrary loops, we then explore the consequences of topolog

Bozhidar Z. Iliev

We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one but it is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it a pure state of some quantum system is described by a state section (a

Bozhidar Z. Iliev

We point out how some mathematically incorrect passages in the paper of M. Reuter can be formulated in a rigorous way. The fibre bundle approach to quantum mechanics developed in quant-ph/9803083, quant-ph/9803084, quant-ph/9804062, quant-ph/9806046, quant-ph/9901039, and quant-ph/9902068 is compared with the one contained in loc. cit.

Bozhidar Z. Iliev

We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one but it is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it a pure state of some quantum system is described by a state section (a

U. Schlöder, H. Engler, U. Schünemann, R. Grimm

We investigate collisional properties of lithium and cesium which are simultaneously confined in a combined magneto-optical trap. Trap-loss collisions between the two species are comprehensively studied. Different inelastic collision channels are identified, and inter-species rate coefficients as well as cross sections are determined. It is found that loss r

Aurel Bulgac, Piotr Magierski

A new algorithm for determining the eigenstates of n-dimensional billiards is presented. It is based on the application of the Cauchy theorem for the determination of the null space of the boundary overlap matrix. The method is free from the limitations associated with the shape of the billiard and could be applied even for nonconvex geometries where other a

Doug Bullock, Jozef H. Przytycki

We describe, for a few small examples, the Kauffman bracket skein algebra of a surface crossed with an interval. If the surface is a punctured torus the result is a quantization of the symmetric algebra in three variables (and an algebra closely related to a cyclic quantization of $U(so_3$). For a torus without boundary we obtain a quantization of "the s

H. Aratyn, L. A. Ferreira, A. H. Zimerman

We analyze the integrability properties of models defined on the symmetric space SU(2)/U(1) in 3+1 dimensions, using a recently proposed approach for integrable theories in any dimension. We point out the key ingredients for a theory to possess an infinite number of local conservation laws, and discuss classes of models with such property. We propose a 3+1-d

The E155 Collaboration, P. L. Anthony et al

We report measurements of the asymmetry A_parallel for inclusive hadron production on longitudinally polarized proton and deuteron targets by circularly polarized photons. The photons were produced via internal and external bremsstrahlung from an electron beam of 48.35 GeV. Asymmetries for both positive and negative signed hadrons, and a subset of identified

Jamal Jalilian-Marian, Xin-Nian Wang

We numerically study the effects of high gluon density at small x on the evolution of gluon distribution function in both hadrons and nuclei. Using a newly derived, Wilson renormalization group-based evolution equation which includes n to 1 gluon ladder fusion, we find significant reduction in nuclear gluon distribution function for large nuclei at zero impa

Taekoon Lee

A scheme is described in which the light gravitino in low energy SUSY breaking models mixes with neutrinos. The mixing between gravitino and neutrinos arises through the standard model symmetry breaking and an R-parity and lepton number violating bilinear term in the superpotential. It is shown that mixings compatible with the neutrino experiments can be obt

UKQCD Collaboration, H. P. Shanahan, P. Boyle, C. T. H. Davies

We present a calculation of the mass of the 1S0 pseudoscalar anti-b c (Bc) state using a non-perturbative measurement from quenched lattice QCD. We find M_Bc = 6.386(9)(98)(15) GeV where the first error is statistical, the second systematic due to the quark mass ambiguities and quenching and the third the systematic error due to the estimation of mass of the

D0 Collaboration

We present a search for charged Higgs bosons in decays of pair-produced top quarks using 109.2 +- 5.8 pb^-1 of data recorded from ppbar collisions at sqrt{s} = 1.8 TeV by the D0 detector during 1992-96 at the Fermilab Tevatron. No evidence is found for charged Higgs production, and most parts of the [m(H+),tan(beta)] parameter space where the decay t -> bH+

Scott Hitchcock

The origin and nature of time in complex systems is explored using quantum (or 'Feynman') clocks and the signals produced by them. Networks of these clocks provide the basis for the evolution of complex systems. The general concept of 'time' is translated into the 'lifetimes' of these unstable configurations of matter. 'Temporal p

Dung-Hai Lee

This work is motivated by a specific point of view: at short distances and high energies the undoped and underdoped cuprates resemble the $π$-flux phase of the t-J model. The purpose of this paper is to present a mechanism by which pairing grows out of the doped $π$-flux phase. According to this mechanism pairing symmetry is determined by a parameter control

Shouvik Datta, K. L. Narasimhan

In this paper, we report on the optical absorption in porous silicon. We model the absorption process assuming that porous silicon is a pseudo 1D material system having a distribution of band gaps. We show that in order to explain the absorption we specifically need to invoke - (a) k is not conserved in optical transitions, (b) the oscillator strength of the

K. Tanaka, F. Marsiglio

We test the canonical BCS wave functions for fixed number of electrons for the attractive Hubbard model. We present results in one dimension for various chain lengths, electron densities, and coupling strengths. The ground-state energy and energy gap to the first excited state are compared with the exact solutions obtained by the Bethe ansatz as well as with

M. Jaime, M. B. Salamon

We revisit the transport properties of La-Ca manganites in detail, since they have been confirmed in a number of CMR-exhibiting materials. We also discuss new data considered the hallmark of an unusually high electron-phonon coupling responsible for charge localization and small polaron transport.

Vasiliki Plerou, Parameswaran Gopikrishnan, Bernd Rosenow, Luis A. Nunes Amaral

We use methods of random matrix theory to analyze the cross-correlation matrix C of price changes of the largest 1000 US stocks for the 2-year period 1994-95. We find that the statistics of most of the eigenvalues in the spectrum of C agree with the predictions of random matrix theory, but there are deviations for a few of the largest eigenvalues. We find th

Toru Sakai

The field-induced transition corresponding to the spin flop in the quantum antiferromagnetic chains in the presence of the Ising-like single-ion anisotropy D (<0) is studied by the finite-cluster analysis. It is found that for $S\geq {3\over 2}$ a first-order metamagnetic transition occurs even in one dimension for small negative D except for the Haldane pha

Jason Harris, Dennis Zaritsky

We measure the angular correlation function of stars in a region of the Large Magellanic Cloud (LMC) that spans 2 degrees by 1.5 degrees. We find that the correlation functions of stellar populations are represented well by exponential functions of the angular separation for separations between 2 and 40 arcmin (corresponding to ~ 30 pc and 550 pc for an LMC

A. A. Melkonian

The properties of the Cosmic Microwave Background Radiation angular autocorrelation function in Friedman Universe with negative curvature (k=-1) are studied. The dependence of the spectral index of autocorrelation function on the density parameter of the Universe is studied numerically, taking into account the effect of geodesic mixing, occuring in k=-1 curv

A. Kull

An analytic collapse model for the formation and density distribution of virialized cold dark matter halos is proposed. Hierarchical structure formation is taken into account explicitly. Monte Carlo methods are used to generate samples of mass histories of virialized halos. The mean density distribution found from the collapse model is in good agreement with

Keith A. Olive, Brian D. Fields

The dual origin of population II Li7, in both big bang nucleosynthesis and galactic cosmic-ray nucleosynthesis is discussed. It is argued that with additional Li6 data, stringent limits on the degree of Li7 depletion can be obtained. Li7 depletion is also constrained by the concordance of big bang predictions with observational determinations of light elemen

Tong Zhou

We express the partition function for an equilibrium system of interacting particles in the canonical ensemble as a functional integration over the particles&#39; density field. We outline a method to evaluate the partition function by expanding around a saddle point. The saddle point is shown to be the solution of the equivalent mean-field theory. Leading c

E. P. Mazets, R. L. Aptekar, P. S. Butterworth, T. L. Cline

In June-July,1998 the Konus-Wind burst spectrometer observed a series of bursts from the new soft gamma repeater SGR1627-41. Time histories and energy spectra of the bursts have been studied, revealing fluences and peak fluxes in the ranges of 3x10^{-7} - 7.5x10^{-6} erg cm^{-2} and 10^{-5} - 10^{-4}erg cm^{-2}/s respectively. One event, 18 June 6153.5sUT st

Charanjit S. Aulakh, Alejandra Melfo, Andrija Rasin, Goran Senjanovic

We show how the renormalizable see-saw mechanism in the context of supersymmetry and spontaneously broken B-L symmetry implies exact R-parity at all energies. We argue that supersymmetry plays an important role in providing a &#34;canonical&#34; form for the see-saw, in particular in grand unified theories that solve the doublet-triplet splitting problem via

P. Christova, M. Jack, T. Riemann

We derive compact analytical formulae of the Bonneau-Martin type for the reaction e+e- to bar-f f gamma with cuts on minimal energy and acollinearity of the fermions, where the photons may be emitted both from the initial or final states. Soft-photon exponentiation is also taken into account.

Stephane Arnouts, Stefano Cristiani, Lauro Moscardini, Sabino Matarrese

(abridged) The evolution of galaxy clustering from z=0 to z=4.5 is analyzed using the angular correlation function and the photometric redshift distribution of galaxies brighter than I_{AB}\le 28.5 in the HDF North. The reliability of the photometric redshift estimates is discussed on the basis of the available spectroscopic redshifts, comparing different co

Bimalendu Deb, Gershon Kurizki

We show that giant quasi-bound diatomic complexes, whose size is typically hundreds of nm, can be formed by intra-cavity cold diatom photoassociation or photodissociation in the strong atom-cavity coupling regime.

M. Gasperini

The pre-big bang scenario describes the evolution of the Universe from an initial state approaching the flat, cold, empty, string perturbative vacuum. The choice of such an initial state is suggested by the present state of our Universe if we accept that the cosmological evolution is (at least partially) duality-symmetric. Recently, the initial conditions of

Christopher D. Carone

We consider gauge unification in nonminimal models with extra spacetime dimensions above the TeV scale. We study the possibility that only a a subset of the supersymmetric standard model gauge and Higgs fields live in the higher dimensional `bulk&#39;. In two of the models we present, a choice for bulk MSSM matter fields can be found that preserves approxima

Antti J. Niemi

We study the geometry of interacting knotted solitons. The interaction is local and advances either as a three-body or as a four-body process, depending on the relative orientation and a degeneracy of the solitons involved. The splitting and adjoining is governed by a four-point vertex in combination with duality transformations. The total linking number is

V. Dmitrašinović, K. Kubodera, F. Myhrer, T. Sato

We present a systematic analysis of next-to-next-to-leading-order diagrams that contribute to the $pp \to ppπ^0$ production at threshold. Analytic expressions are given for the effective transition operators, and the relative importance of various types of diagrams is discussed. The vertex-correction-type graphs are found to give only small corrections to lo

Gordey B. Lesovik, Thierry Martin, Julien Torres

A singularity at the Josephson frequency in the noise spectral density of a disordered normal metal -- superconductor junction is predicted for bias voltages below the superconducting gap. The non-stationary Aharonov-Bohm effect, recently introduced for normal metals, is proposed as a tool for detecting this singularity. In the presence of a harmonic externa

B. Ananthanarayan, P. N. Pandita

We investigate the infra-red stable fixed points of the Yukawa couplings in the minimal version of the supersymmetric standard model with R-parity violation. Retaining only the R-parity violating couplings of higher generations, we analytically study the solutions of the renormalization group equations of these couplings together with the top- and b-quark Yu

Probir Roy, K. Sridhar

An unambiguous identification of glueballs in experiments will be of great significance, because their existence is an important test of QCD. The proposal, advanced here, is to experimentally search for glueballs as peaks in the invariant mass of a leading K_S-pair fragmenting from an energetic gluon jet out of high-statistics three-jet events in hadronic de

You-Quan Li, Micheal Ma, Da-Ning Shi, Fu-Chun Zhang

The one dimensional Heisenberg model in the presence of orbital degeneracy is studied at the SU(4) symmetric viewpoint by means of Bethe ansatz. Following Sutherland&#39;s previous work on an equivalent model, we discuss the ground state and the low-lying excitations more extensively in connection to the spin systems with orbital degeneracy. We show explicit

Masashige Matsumoto, Manfred Sigrist

The electronic states near a surface or a domain wall in the p-wave superconductor are studied for the order parameter of the form p_x\pm i p_y-wave, which is a unitary odd-parity state with broken time-reversal symmetry. This state has been recently suggested as the superconducting state of Sr_2 Ru O_4. The spatial variation of the order parameter and vecto

Y. A. Markov, M. A. Markova

On the basis of the semiclassical equations for quark-gluon plasma (QGP) and Yang-Mills equation, the generalized kinetic equation for waves with regard to its interaction is obtained. The physical mechanisms defining nonlinear scattering of a plasmon by QGP particles are analysed. The problem on a connection of nonlinear Landau damping rate of longitudinal

Philip J. Armitage, Priyamvada Natarajan

Misaligned accretion disks surrounding rotating compact objects experience a torque due to the Lense-Thirring effect, which leads to precession of the inner disk. It has been suggested that this effect could be responsible for some low frequency Quasi-Periodic Oscillations observed in the X-ray lightcurves of neutron star and galactic black hole systems. We

David Heyrovsky, Dimitar Sasselov, Abraham Loeb

Gravitational microlensing provides a new technique for studying the surfaces of distant stars. Microlensing events are detected in real time and can be followed up with precision photometry and spectroscopy. This method is particularly adequate for studying red giants in the Galactic bulge. Recently we developed an efficient method capable of computing the

S. R. Kulkarni, S. G. Djorgovski, S. C. Odewahn, J. S. Bloom

Afterglow, or long-lived emission, has now been detected from about a dozen well-positioned gamma-ray bursts. Distance determinations made by measuring optical emission lines from the host galaxy, or absorption lines in the afterglow spectrum, place the burst sources at significant cosmological distances, with redshifts ranging from ~1--3. The energy require

S. E. Derkachov

Applying the Pasquier-Gaudin procedure we construct the Baxter&#39;s Q-operator for the homogeneous XXX model as integral operator in standard representation of SL(2). The connection between Q-operator and local Hamiltonians is discussed. It is shown that operator of Lipatov&#39;s duality symmetry arises naturally as leading term of the asymptotic expansion

H. A. Aslanyan, A. R. Mkrtchyan, A. H. Mkrtchian

The paper is devoted to the study of the influence of crystalline lattice distortions due to external excitations (acoustic vibrations, temperature gradient, etc.) on the Quasicerenkov radiation. Equations describing Quasicerenkov radiation of charged particles in distorted crystals are derived. These equations are solved numerically. It is shown that certai

Jan M. L. Martin, Peter R. Taylor

In order to resolve a significant uncertainty in the heat of vaporization of silicon -- a fundamental parameter in gas-phase thermochemistry -- $ΔH^\circ_{f,0}$[Si(g)] has been determined from a thermochemical cycle involving the precisely known experimental heats of formation of SiF_4(g) and F(g) and a benchmark calculation of the total atomization energy (

Mette Machholm, Paul S. Julienne, Kalle-Antti Suominen

We use quantum scattering methods to calculate the light-induced collisional loss of laser-cooled and trapped magnesium atoms for detunings up to 30 atomic linewidths to the red of the 1S_0-1P_1 cooling transition. Magnesium has no hyperfine structure to complicate the theoretical studies. We evaluate both the radiative and nonradiative mechanisms of trap lo

Zhaoping Li, John Hertz

We present a model of a coupled system of the olfactory bulb and cortex. Odor inputs to the epithelium are transformed to oscillatory bulbar activities. The cortex recognizes the odor by resonating to the bulbar oscillating pattern when the amplitude and phase patterns from the bulb match an odor memory stored in the intracortical synapses. We assume a corti

Pavel S. Kamenov

&#34;Does God play dice with the Universe?&#34; The natural width of excited hydrogen atoms are found using the Bohr&#39;s model of this atom and de Broglie&#39;s ideas. The mean life time of the excited states is a characteristic only of a statistical ensemble of many atoms.

Radoslaw Szmytkowski

Closure relations satisfied by the radial Dirac-Coulomb Sturmians are proved analytically. The Sturmian expansion of the Dirac-Coulomb Green function is transformed to the form containing only series with summations running over non-negative indices. The main paper was published in J. Phys. B: At. Mol. Opt. Phys. 30 (1997) 825-61 [Erratum: 30 (1997) 2747], s

Mikhail M. Bogdan, Arnold M. Kosevich, Gerard A. Maugin

The concept of soliton complex in a nonlinear dispersive medium is proposed. It is shown that strongly interacting identical topological solitons in the medium can form bound soliton complexes which move without radiation. This phenomenon is considered to be universal and applicable to various physical systems. The soliton complex and its &#34;excited&#34; s

L. M. Kovachev

Using the method of separation of variables, we developed a vector nonparaxial theory for the nonlinear wave equations in strong field approximation. We found that exact localized vortex soliton solution exists for the nonlinear 3D+1 vector wave equation and for 3D+1 vector nonlinear Schrödinger equation. This method is applicable for angular functions, whic

J. C. Fernandes, R. Crespo, F. M. Nunes, I. J. Thompson

The transfer reaction $^7{\rm Be(d,n)}^8{\rm B}$ is modelled for the recent low experimental energies using the DWBA. Tests of the validity of the ANC method for the extraction of the $S_{17}$ astrophysical factor are performed. We show that a peripheral assumption is no longer accurate for center of mass energies greater than approximately 15 MeV. In all ca

N. Kaiser

We analyze the recent total cross section data for $pp \to pΛK^+$ near threshold measured at COSY. Using an effective range approximation for the on-shell $pΛ$ S-wave final state interaction we extract from these data the combination ${\cal K} = \sqrt{2|K_s|^2+|K_t|^2} = 0.38$ fm$^4$ of the singlet ($K_s$) and triplet ($K_t$) threshold transition amplitudes.

Václav Špička, Pavel Lipavský, Klaus Morawetz

Binary collisions in Fermi systems obey two fundamental symmetries corresponding to the space and time inversion and to the interchange of particles and holes. We show that beyond the local and instant approximation of scattering-in and -out integrals of a kinetic equation, only one of symmetries can be explicit while the other has to be covered by a constra

V. M. Kolybasov

It is shown that the true parameters of He-4-Sigma differ from the observed ones. The reason is that the amplitude of He-4-Sigma production in the reaction He-4(K-,pi-) sharply varies just in the corresponding mass region. It leads to the small, but noticeable shift of the binding energy and the width. Besides, the data at the threshold of Sigma-0 production

I. Chemakin, V. Cianciolo, B. A. Cole, R. Fernow

First results are presented from BNL experiment E910 on pion production and stopping in proton-Be, Cu, and Au collisions at a beam momentum of 18 GeV/c. We characterize the centrality of the collisions using the measured number of &#34;grey&#34; tracks, Ngrey,and a derived quantity, nu, the number of inelastic nucleon-nucleon scatterings suffered by the proj

Oded Schramm, Boris Tsirelson

Noise sensitivity of functions on the leaves of a binary tree is studied, and a hypercontractive inequality is obtained. We deduce that the spider walk is not noise stable.

F. Pugliese, A. Vinogradov

It is shown that a lagrangian system whose Legendre transformation degenerates along a hypersurface behaves in a strange manner by jumping from time to time without any &#39;&#39;visible cause&#39;&#39;. In such a jump the system changes instantaneously its coordinates as well as its momenta. The mathematical dscription of the phenomenon is based on the theo

Matthias Lesch

We consider a regular singular Sturm-Liouville operator $L:=-\frac{d^2}{dx^2} + \frac{q(x)}{x^2 (1-x)^2}$ on the line segment $[0,1]$. We impose certain boundary conditions such that we obtain a semi-bounded self-adjoint operator. It is known that the $ζ$-function of this operator $ζ_L(s)=\sum_{λ\in\spec(L)\setminus\{0\}} λ^{-s}$ has a meromorphic continuati

Hironobu Ishihara

Let $E$ be an ample vector bundle of rank $r$ on a projective variety $X$ with only log-terminal singularities. We consider the nefness of adjoint divisors $K_X+(t-r)det(E)$ when $t>=dim(X)$ and $t>r$. As a corollary, we classify pairs $(X,E)$ with $c_r$-sectional genus zero.

Ch. Charitos, G. Tsapogas

For metric spaces with curvature less than or equal to x, x<0, it is shown that a recurrent geodesic can be approximated by closed geodesics. A counter example is provided for the converse.

Fouad Chaatit, Haskell P. Rosenthal

Extrinsic and intrinsic characterizations are given for the class DSC(K) of differences of semi-continuous functions on a Polish space K, and also decomposition characterizations of DSC(K) and the class PS(K) of pointwise stabilizing functions on K are obtained in terms of behavior restricted to ambiguous sets. The main, extrinsic characterization is given i

A. P. Veselov

A special class of solutions to the generalised WDVV equations related to a finite set of covectors is investigated. Some geometric conditions on such a set which guarantee that the corresponding function satisfies WDVV equations are found (check-conditions). These conditions are satisfied for all root systems and their special deformations discovered in the

Giuseppe Vitiello

Kinks, vortices, monopoles are extended objects, or defects, of quantum origin with topologically non-trivial properties and macroscopic behavior. They are described in Quantum Field Theory in terms of non-homogeneous boson condensation. I will review the related QFT formalism, the spontaneous breakdown of symmetry framework in which the defects appear and d

H. Grosse, A. Strohmaier

We give a noncommutative version of the complex projective space CP^2 and show that scalar QFT on this space is free of UV divergencies. The tools necessary to investigate Quantum fields on this fuzzy CP^2 are developed and possibilities to introduce spinors and Dirac operators are discussed.

Marc Henneaux

The requirement that the action be stationary for solutions of the Dirac equations in anti-de Sitter space with a definite asymptotic behaviour is shown to fix the boundary term (with its coefficient) that must be added to the standard Dirac action in the AdS/CFT correspondence for spinor fields.

Marijan Ribaric, Luka Sustersic

We put forward an example of local, covariant Lagrangians where the Feynman rules result in diagrams of QED but with regularized propagators. Following &#39;t Hooft and Veltman, these diagrams may be taken to define a quantum field theory of electrodynamic phenomena that requires no regularization and is realistic, because: (i) The corresponding Green&#39;s

Eugene Shuster

In this paper we construct several supersymmetric theories, including SU(N) gauge theory, on AdS_5 background. We discuss the proper definition of the Killing equation for the symplectic Majorana spinors required in AdS_5 supersymmetric theories. We find that the symplectic Killing spinor equation involves a matrix M in the USp(2N) indices whose role was not

A. G. Shuvaev, K. J. Golec-Biernat, A. D. Martin, M. G. Ryskin

We show that the off-diagonal (or skewed) parton distributions are completely determined at small $x$ and $ξ$ by the (conventional) diagonal partons. We present predictions which can be used to estimate the off-diagonal distributions at small $x$ and $ξ$ at any scale.

C. A de S. Pires

In this work we study the structure of the electromagnetic interactions and the electric charge quantization in gauge theories of electroweak interactions based on semi-simple groups. We show that in the standard model of the electroweak interactions the structure of the electromagnetic interactions is strongly correlated to the quantization pattern of the e

S. M. Troshin, N. E. Tyurin

On the basis of the U-matrix method of the s-channel unitarization we obtain a new unitarity bound for the single-helicity-flip amplitude F_5 of elastic pp-scattering at small values of t

V. Kuvshinov, R. Shulyakovsky

General formula for inclusive gluon distribution on rapidities is obtained for the processes of multigluon production in classical instanton field with the first quantum correction. On the basis of this formula second correlation function is calculated in QCD and analyzed. The features of the correlation function behaviour can be used as a signal of instanto

V. Kuvshinov, V. Shaporov

We study evolution of colour gluons and prove the possibility of gluon squeezed states at the nonperturbative QCD jet stage. Angular and rapidity dependences of squeezed gluon second correlation function are studied. We demonstrate that the new gluon states can have both sub-poissonian and super-poissonian statistics corresponding to antibunching and bunchin

U. Ellwanger, C. Hugonie

We study the constraints on the parameter space of the supersymmetric standard model extended by a gauge singlet, which arise from the absence of global minima of the effective potential with slepton or squark vevs. Particular attention is paid to the so-called ``UFB&#39;&#39; directions in field space, which are F-flat in the MSSM. Although these directions

S. Binner, J. H. Kuehn, K. Melnikov

We propose to use events with radiated photons in e^+e^- collisions to measure the total cross section of e^+ e^- \to hadrons as a function of the center of mass energy. The Monte Carlo simulation for the collider DAPHNE shows that a competitive accuracy can be achieved with this method.

H. Heiselberg

The electrical conductivity has been calculated in the early universe at temperatures below as well as above the electroweak vacuum scale, $T_c\simeq 100$GeV. Debye and dynamical screening of electric and magnetic interactions leads to a finite conductivity, $σ_{el}\sim T/α\ln(1/α)$, at temperatures well below $T_c$. At temperatures above, $W^\pm$ charge-exc

K. Agashe, N. G. Deshpande

We suggest two methods (based on flavor SU(3) symmetry) to determine the CKM angle $γ$ using the decays $B_d$, $B^+ \to K η(η&#39;)$ and $B_s \to πη(η&#39;)$, respectively. Rescattering effects are partly included -- we neglect annihilation amplitudes, but do not assume any other relation between the SU(3) invariant amplitudes. We use the fact that the ampli

M. C. Bento

We study maximally symmetric cosmological solutions of type II supersymmetric strings in the presence of the exact, SL(2,Z)-invariant, higher-curvature corrections to the lowest order effective action. We find that, unlike the case of type IIA theories, de Sitter solutions exist, at all orders in $α&#39;$, for type IIB superstrings, when non-perturbative ins

T. Dereli, R. W. Tucker

We explore the role of the Cremmer-Scherk mechanism in the context of low energy effective string theory by coupling the antisymmetric 3-form gauge potential to an Abelian gauge potential carrying weak hypercharge. The theory admits a class of exact self-gravitating solutions in the spontaneously broken phase in which the dual fields acquire massive perturba

Patrik Henelius

It has proved difficult to extend the density matrix renormalization group technique to large two-dimensional systems. In this Communication I present a novel approach where the calculation is done directly in two dimensions. This makes it possible to use an infinite system method, and for the first time the fixed point in two dimensions is studied. By analy

Max Petersen, Frank Wagner, Lars Hufnagel, Matthias Scheffler

The full-potential linearized augmented-plane wave (FP-LAPW) method is well known to enable most accurate calculations of the electronic structure and magnetic properties of crystals and surfaces. The implementation of atomic forces has greatly increased it&#39;s applicability, but it is still generally believed that FP-LAPW calculations require substantial

A. V. Postnikov, B. Schneider, M. Neumann, D. Hartmann

The new results are presented of the experimental study of KNbO3 and KTaO3 by means of X-ray photoelectron spectroscopy, soft X-ray emission and X-ray fluorescence spectroscopy. In particular, Nb M(4,5) spectra have been measured over a range of near-threshold excitation energies 206.5 - 240.6 eV, and Ta N(3) spectra over 399.4 - 420.4 eV at the Advance Ligh

S. T. Chui, P. Ao

We investigate analytically the non-equilibrium spatial phase segregation process of a mixture of alkali Bose-Einstein condensates. Two stages (I and II) are found in analogy to the classical spinodal decomposition. The coupled non-linear Schrödinger equations enable us to give a quantitative picture of the present dynamical process in a square well trap. Bo

A. V. Postnikov, V. Caciuc, G. Borstel

The equilibrium ground-state structure of LiNbO3 in the paraelectric and ferroelectric phases is fully optimized in a first-principles calculation using the full-potential linearized augmented plane wave method. The equilibrium volume, c/a ratio and all (four, in the ferroelectric phase) internal parameters are found to be in good agreement with the experime

P. Nozieres, F. Pistolesi

We consider a two dimensional semiconductor with a local attraction among the carriers. We study the ground state of this system as a function of the semiconductor gap. We find a direct transition from a superconducting to an insulating phase for no doping at a critical value, the single particle excitations being always gapped. For finite doping we find a s

Goetz S. Uhrig, Friedhelm Schoenfeld, Jean-Paul Boucher, Mladen Horvatic

It is shown that nonadiabatic fluctuations of the soliton lattice in the spin-Peierls system CuGeO_3 lead to an important reduction of the NMR line widths. These fluctuations are the zero-point motion of the massless phasonic excitations. Furthermore, we show that the discrepancy of X-ray and NMR soliton widths can be understood as the difference between a d

R. A. Klemm, C. T. Rieck, K. Scharnberg

Li et al. found that the critical current density JcJ across atomically clean c-axis twist junctions of Bi2Sr2CaCu2O(8+x) is the same as that of the constituent single crystal, JcS, independent of the twist angle phi0, even at Tc. We investigated theoretically if a dx2-y2-wave order parameter might twist by mixing in dxy components, but find that such twisti

S. Tornow, O. Entin-Wohlman, A. Aharony

We present a detailed calculation of the magnetic couplings between nearest-neighbor and next-nearest-neighbor coppers in the edge-sharing geometry, ubiquitous in many cuprates. In this geometry, the interaction between nearest neighbor coppers is mediated via two oxygens, and the Cu-O-Cu angle is close to 90 degrees. The derivation is based on a perturbatio

H. Bokil, A. J. Bray, B. Drossel, M. A. Moore

Using Monte Carlo simulations (MCS) and the Migdal-Kadanoff approximation (MKA), Marinari et al. study in their comment on our paper the link overlap between two replicas of a three-dimensional Ising spin glass in the presence of a coupling between the replicas. They claim that the results of the MCS indicate replica symmetry breaking (RSB), while those of t

J. Schlipf, M. Jarrell, P. G. J. van Dongen, N. Blümer

The nature of the Mott-Hubbard metal-insulator transition in the infinite-dimensional Hubbard model is investigated by Quantum Monte Carlo simulations down to temperature T=W/140 (W=bandwidth). Calculating with significantly higher precision than in previous work, we show that the hysteresis below T_{IPT}\simeq 0.022W, reported in earlier studies, disappears

S. Okamoto, S. Ishihara, S. Maekawa

The spin and orbital phase diagram for perovskite manganites are investigated as a function of temperature and hole concentration. The superexchange and double exchange interactions dominate the ferromagnetic phases in the low and high concentration regions of doped holes, respectively.The two interactions favor different orbital states each other. Between t

M. Nohara, M. Isshiki, F. Sakai, H. Takagi

The quasiparticle density of states (DOS) in the vortex state has been probed by specific heat measurements under magnetic fields (H) for clean and dirty s-wave superconductors, Y(Ni1-xPtx)2B2C and Nb1-xTaxSe2. We find that the quasiparticle DOS per vortex is appreciably H-dependent in the clean-limit superconductors, while it is H-independent in the dirty s