October 2005 arXiv papers — page 15

Ludwik Dabrowski, Alexander Andreev, Mladen Georgiev

Recent experimental data on the diffusion coefficient of carbon in alpha-iron below liquid nitrogen temperature (LNT) question the classical approach to the observed temperature dependence. As the temperature is lowered below LNT, the diffusion constant tends to a nearly temperature-independent value rather than continuing its activated trend. The low temper

V. P. Mineev, K. V. Samokhin

We show how the de Haas-van Alphen effect can be used to directly measure the magnitude of spin-orbit coupling in non-centrosymmetric metals, such as CePt3Si and LaPt3Si.

J. Gonzalez, E. Perfetto

We investigate the electronic instabilities of the small-diameter (3,3) carbon nanotubes by studying the low-energy perturbations of the normal Luttinger liquid regime. The bosonization approach is adopted to deal exactly with the interactions in the forward-scattering channels, while renormalization group methods are used to analyze the low-energy instabili

W. Orellana, P. Fuentealba

The stability and properties of the monovacancy and the divacancy in single-walled carbon nanotubes (CNTs) are addressed by spin-density functional calculations. We study these defects in four nanotubes, the armchair (6,6) and (8,8) and the zigzag (10,0) and (14,0), which have diameters of about 8 and 11 Å, respectively. We also study different defect concen

Michael W. Jack, Han Pu

An unstable condensate of diatomic molecules will coherently disassociate into correlated pairs of atoms. This dissociation process exhibits very rich quantum dynamics depending on the quantum statistics of the constituent atoms. We show that in the case of bosonic atoms Bose-enhancement can lead to stimulated dissociation, whereas, in the case of fermions P

Yogesh Singh, R. S. Sannabhadti, S. Ramakrishnan

We report the preparation and results of our magnetic and transport measurements on a new Yb-based ternary compound Yb$_2$Ir$_3$Sn$_5$. This compound forms in the orthorhombic Cmc21 structure. DC magnetic susceptibility between 1.8 K and 300 K reveal that Yb is in its magnetic trivalent state in this compound. Electrical resistivity measurements down to 1. 5

Oleg Derzhko, Johannes Richter, Jörg Schulenburg

We study the stability of some strongly frustrated antiferromagnetic spin lattices in high magnetic fields against lattice distortions. In particular, we consider a spin-s anisotropic Heisenberg antiferromagnet on the square-kagomé and kagomé lattices. The independent localized magnons embedded in a ferromagnetic environment, which are the ground state at th

Rhonda Dzakpasu, Michał Żochowski

We investigate the effects of transmission delays on the formation of temporally ordered states in networks of non-identical Rössler oscillators, having SWN topology. We show that incorporation of two different types of delay, length independent and length dependent, leads to dramatically different temporal properties of the network. In the first case format

J. Simonin

We analyze the consequences of a first-order (in the effective Kondo coupling) inter-impurity correlation present in the Two-Impurity Anderson Hamiltonian. This correlation generates a pair of Kondo Doublet states which are responsible for the first (higher energy) Kondo stage of these systems. Applied to systems of quantum dots in a semiconductor heterolaye

John M. Baker

Starting from a model of an elastic medium, we derive equations of motion that are identical in form to Dirac's equation for a spin 1/2 particle with mass, coupled to electromagnetic and gravitational interactions. The mass and electromagnetic terms are not added by hand but emerge naturally from the formalism. A two dimensional version of this equation

J. Marciak-Kozlowska, M. Kozlowski

In this paper the interaction of ultrashort laser pulses with matter is investigated. The scattering and potential motion of heat carriers, as well as the external force are considered. It is shown that the heat transport is described by the Proca equation. For thermal Heisenberg type relation Vτ~ \hbar, (τis the relaxation time and V is the potential) the s

Victor Teboul

Finite size effects on dynamical heterogeneity are studied in liquid silica with Molecular Dynamics simulations using the BKS potential model. When the system size decreases relaxation times are found to increase in accordance with previous results in finite-size simulations and confined liquids. It has been suggested that this increase may be related to a m

S. Mossa, G. Tarjus

We present an operational method to determine the 'locally preferred structure'' of model liquids, a notion often put forward to explain supercooling of a liquid and glass formation. The method relies on finding the global minimum in the (free) energy landscape of clusters of atoms or molecules embedded in a liquid-like environment. We propose a

V. N. Glazkov, A. I. Smirnov, J. P. Sanchez, A. Forget

Single-ion anisotropy is of importance for the magnetic ordering of the frustrated pyrochlore antiferromagnets Gd2Ti2O7 and Gd2Sn2O7. The anisotropy parameters for the Gd2Sn2O7 were measured using the electron spin resonance (ESR) technique. The anisotropy was found to be of the easy plane type, with the main constant D=140mK. This value is 35% smaller than

Wenan Guo, Xiaofeng Qian, Henk W. J. Blöte, F. Y. Wu

We consider a special case of the n-component cubic model on the square lattice, for which an expansion exists in Ising-like graphs. We construct a transfer matrix and perform a finite-size-scaling analysis to determine the critical points for several values of n. Furthermore we determine several universal quantities, including three critical exponents. For

Alessandro Silva

We study the tails of the density of states (DOS) in a diffusive superconductor-normal metal-superconductor (SNS) junction below the Thouless gap. We show that long-wave fluctuations of the concentration of impurities in the normal layer lead to the formation of subgap quasiparticle states, and calculate the associated subgap DOS in all effective dimensional

György Vankó, Jean-Pascal Rueff, Aleksi Mattila, Zoltán Németh

We report the continuous variation of the spin moment of cobalt in LaCoO3 across its temperature and pressure-induced spin transitions evidenced with Kβemission spectra. The first thermal transition is best described by a transition to an orbitally nondegenerate intermediate spin (S=1) state. In parallel, continuous redistribution of the 3d electrons is also

J. -Ph. Jay, F. Petit, J. Ben Youssef, M. V. Indenbom

Magnetic and magnetostrictive hysteresis loops of TbCo/CoFe multilayers under field applied along the hard magnetization axis are studied using vectorial magnetization measurements, optical deflectometry and magneto optical Kerr microscopy. Even a very small angle misalignment between hard axis and magnetic field direction is shown to drastically change the

X. Hu, L. He, L. Yin, Z. H. Ning

We show that the longitudinal current-voltage characteristics of superconductors in mixed state have the general form of extended power law. Isotherms simulated from this nonlinear equation fit the experimental I-V data of Strachan et al. [ Phys. Rev. Lett. {\bf 87}, 067007 (2001)]. We determine the average pinning force in the flux creep and strong pinning

Jian Wang, Jian-Sheng Wang

We propose to use l_0/(l_0+L) for the energy transmission covering both ballistic and diffusive regimes, where l_0 is mean free path and L is system length. This formula is applied to heat conduction in carbon nanotubes (CNTs). Calculations of thermal conduction show: (1) Thermal conductance at room temperature is proportional to the diameter of CNTs for sin

Boris Grbic, Renaud Leturcq, Klaus Ensslin, Dirk Reuter

A single-hole transistor is patterned in a p-type, C-doped GaAs/AlGaAs heterostructure by AFM oxidation lithography. Clear Coulomb blockade resonances have been observed at T=300 mK. A charging energy of ~ 1.5 meV is extracted from Coulomb diamond measurements, in agreement with the lithographic dimensions of the dot. The absence of excited states in Coulomb

Mika Sillanpaa, Teijo Lehtinen, Antti Paila, Yuriy Makhlin

Quantum-mechanical systems having two discrete energy levels are ubiquitous in nature. For crossing energy levels, depending on how fast they approach each other, there is a possibility of a transition between them. This phenomenon is known as Landau-Zener tunneling and it forms the physical basis of the Zener diode, for example. The traditional treatment of

Jan von Delft, Florian Marquardt, R. A. Smith, Vinay Ambegaokar

This is the second in a series of two papers (I and II) on the problem of decoherence in weak localization. In paper I, we discussed how the Pauli principle could be incorporated into an influence functional approach for calculating the Cooperon propagator and the magnetoconductivity. In the present paper II, we check and confirm the results so obtained by d

Florian Marquardt, Jan von Delft, R. A. Smith, Vinay Ambegaokar

This is the first in a series of two papers (I and II), in which we revisit the problem of decoherence in weak localization. The basic challenge addressed in our work is to calculate the decoherence of electrons interacting with a quantum-mechanical environment, while taking proper account of the Pauli principle. First, we review the usual influence function

Ol'ga V. Dimitrova, M. V. Feigel'man

The effect of Rashba spin-orbital interaction upon supercurrent in S-2DEG-S proximity junctions is investigated in the clean limit. Generalization of Beenakker's formula for Andreev levels to the case of spin-orbital scattering is presented. Spin-orbit - induced splitting of Andreev bound-states is predicted for a junction of infinite width, and with non

A. F. van Driel, G. Allan, C. Delerue, P. Lodahl

We studied the rate of spontaneous emission from colloidal CdSe and CdTe nanocrystals at room temperature. The decay rate, obtained from luminescence decay curves, increases with the emission frequency in a supra-linear way. This dependence is explained by the thermal occupation of dark exciton states at room temperature, giving rise to a strong attenuation

D. A. Ryndyk, M. Hartung, G. Cuniberti

We consider the nonequilibrium quantum vibrations of a molecule clamped between two macroscopic leads in a current-carrying state at finite voltages. Our approach is based on the nonequilibrium Green function technique and the self-consistent Born approximation. Kinetic equations for the average populations of electrons and vibrons are formulated in the weak

Ralf Schützhold, Michael Uhlmann, Yan Xu, Uwe R. Fischer

We present a formal derivation of the mean-field expansion for dilute Bose-Einstein condensates with two-particle interaction potentials which are weak and finite-range, but otherwise arbitrary. The expansion allows for a controlled investigation of the impact of microscopic interaction details (e.g., the scaling behavior) on the mean-field approach and the

Andrey E. Miroshnichenko, Yuri S. Kivshar

We study transmission properties of discrete networks composed of linear arrays coupled to systems of N side defects, and demonstrate the basic principles of the resonant scattering management through engineering Fano resonances. We find exact solutions for the wave transmission coefficient and reveal the conditions for the perfect reflections and transmissi

L. L. Bonilla, R. Escobedo

A Wigner-Poisson kinetic equation describing charge transport in doped semiconductor superlattices is proposed. Electrons are supposed to occupy the lowest miniband, exchange of lateral momentum is ignored and the electron-electron interaction is treated in the Hartree approximation. There are elastic collisions with impurities and inelastic collisions with

N. A. Buznikov, A. S. Antonov, A. B. Granovsky, C. G. Kim

The giant magnetoimpedance effect in composite wires consising of a non-magnetic inner core and soft magnetic shell is studied theoretically. It is assumed that the magnetic shell has a helical anisotropy. The current and field distributions in the composite wire are found by means of a simultaneous solution of Maxwell equations and the Landau-Lifshitz equat

D. B. Dougherty, C. Tao, O. Bondarchuk, W. G. Cullen

The effects of sampling rate and total measurement time have been determined for single-point measurements of step fluctuations within the context of first-passage properties. Time dependent STM has been used to evaluate step fluctuations on Ag(111) films grown on mica as a function of temperature (300-410 K), on screw dislocations on the facets of Pb crysta

D. M. Smith, W. A. Heindl, C. B. Markwardt, J. H. Swank

XTE J1739-302 is a transient X-ray source with unusually short outbursts, lasting on the order of hours. Here we give a summary of X-ray observations we have made of this object in outburst with the Rossi X-ray Timing Explorer (RXTE) and at a low level of activity with the Chandra X-ray Observatory, as well as observations made by other groups. Visible and i

Steen H. Hansen, Joachim Stadel

One can solve the Jeans equation analytically for equilibrated dark matter structures, once given two pieces of input from numerical simulations. These inputs are 1) a connection between phase-space density and radius, and 2) a connection between velocity anisotropy and density slope, the α-βrelation. The first (phase-space density v.s. radius) has already b

Alan McConnachie, Mike Irwin

(Abridged) The spatial distribution of the Galactic satellite system plays an important role in Galactic dynamics and cosmology, where its successful reproduction is a key test of simulations of galaxy halo formation. Here, we examine its representative nature by conducting an analysis of the 3-dimensional spatial distribution of the M31 subgroup of galaxies

Zdenek Mikulasek, Augustin Skopal, Miloslav Zejda, Ondrej Pejcha

We present an analysis of light variations in UBVRI of the anomalous object in the center of planetary nebula Sh 2-71. We refined the linear ephemeris of the light maxima to JD{max} = 2449862.0 + 68.101 (E-96), but also identified long-term, obviously non-periodic variations. The latter manifest themselves in large O-C shifts, a variable profile of light cur

F. J. Sanchez-Salcedo

In this paper we consider the viability of these non-gravitational torques to take the gas off the plane. We show that magnetically generated warps are clearly flawed because they would wrap up into a spiral in less than two or three galactic rotations. The inclusion of any magnetic diffusivity to dilute the wrapping effect, causes the amplitude of the warp

David. H Lyth, Karim A. Malik, Misao Sasaki, Ignacio Zaballa

Previous authors have calculated the mass function of primordial black holes only on scales which are well outside the horizon at the end of inflation. Here we extend the calculation to sub-horizon scales, on which the density perturbation never becomes classical. Regarding the formation of black holes as a `measurement' of the (high peaks) of the densit

A. Miglio, J. Montalban, A. Noels

In main-sequence stars, the chemical composition gradient that develops at the edge of the convective core is responsible for a non-uniform period spacing of high-order gravity modes. In this work we investigate, in the case of a 1.6 Msun star, the effects on the period-spacing of extra mixing processes in the core (such as diffusion and overshooting).

R. Iaria, T. Di Salvo, N. R. Robba, L. Burderi

We present the results of a 45 ks Chandra observation of the high-mass X-ray binary Cen X--3 at orbital phases between 0.13 and 0.40 (in the eclipse post-egress phases). Here we concentrate on the study of discrete features in the energy spectrum at energies between 6 and 7 keV, i.e. on the iron K$_α$ line region, using the High Energy Transmission Grating S

Anwesh Mazumdar

We propose a new kind of seismic diagram, based on the determination of the locations of sharp acoustic features inside a star. We show that by combining the information about the position of the base of the convective envelope or the second helium ionisation zone with a measure of the average large separation, it is possible to constrain the unknown paramet

V. R. Eke, C. M. Baugh, S. Cole, C. S. Frenk

The abundance of galaxy clusters as a function of mass is determined using the 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) catalogue. This is used to estimate the amplitude of the matter fluctuation spectrum, parametrised by the linear theory rms density fluctuations in spheres of 8Mpc/h, sigma_8. The best-fitting value for this parameter is highly corr

Natalia Babkovskaia, Juri Poutanen

We study the conditions for operation of the 22 GHz ortho-water maser in a dusty medium near late-type stars. The main physical processes, such as exchange of energy between dust and gas in the radiation field of a star, radiative cooling by water molecules and pumping of water masers are described self-consistently. We show that the presence of dust grains

Floris van der Tak, Malcolm Walmsley, Fabrice Herpin, Cecilia Ceccarelli

Single-dish spectra and interferometric maps of (sub)mm lines of H2O-18 and HDO are used to study the chemistry of water in eight regions of high-mass star formation. The spectra indicate HDO excitation temperatures of ~110 K and column densities in an 11'' beam of ~2x10^14 cm^-2 for HDO and ~2x10^17 cm^-2 for H2O, with the N(HDO)/N(H2O) ratio increa

D. Carollo, B. Bucciarelli, S. T. Hodgkin, M. G. Lattanzi

The GSC-II white dwarf survey was designed to identify faint and high proper motion objects, which we used to define a new and independent sample of cool white dwarfs. With this survey we aim to derive new constraints on the halo white dwarf space density. Also, these data can provide information on the age of thick disk and halo through the analysis of the

Y. P. Wang

We model the constraints set on the evolution of dusty starburst galaxies by the current deep extragalactic surveys performed in the far-infrared with $\it Spitzer$, and at radio wavelengths with the VLA. Our models fit the number counts in all the available spectral bands well, and also provide a reasonably close match to the redshift distribution of the $\

C. Dominik, C. Ceccarelli, D. Hollenbach, M. Kaufman

Recent observations of the ground state transition of HDO at 464 GHz towards the protoplanetary disk of DM Tau have detected the presence of water vapor in the regions just above the outer disk midplane (Ceccarelli et al 2005). In the absence of non-thermal desorption processes, water should be almost entirely frozen onto the grain mantles and HDO undetectab

B. Tingley, C. Thurl, P. D. Sackett

Exoplanetary transits produce a double-horned color signature that is distinct from both binaries and blends and can thus be used to separate exoplanets from false positives in transit searches. Color photometry with precision sufficient to detect this signal in transits of HD 209458 is available in the literature. Analysis of these observations reveals that

L. Zappacosta, D. A. Buote, F. Gastaldello, P. J. Humphrey

We have analyzed an XMM-Newton observation of the cluster Abell 2589. Apart from a low-level asymmetry in the central region, the cluster appears very relaxed and does not show presence of a central AGN. We derived constraints for the radial temperature, density and, assuming hydrostatic equilibrium, mass profiles. We find that the best fit to the dark matte

Judith G. Cohen, Keith Matthews, P. Brian Cameron

We present observations made with the newly commissioned Keck laser-guide star adaptive optics system of 6 objects in M31 that are alleged in multiple recent studies to be young globular clusters (GCs); all are supposed to have ages less than 5 Gyr. The resulting FWHM of the PSF core in our images is ~70 mas. The four youngest of these objects are asterisms;

Jiangyong Jia

PHENIX has measured the two particle azimuth correlation in Au + Au at $\sqrt{s}$ = 200 GeV. Jet shape and yield at the away side are found to be strongly modified at intermediate and low $p_T$. The modifications vary dramatically with $p_T$ and centrality. At high $p_T$, away side jet peak reappears but the yield is suppressed. Similar jet strength is found

Zachary B. Walters, Robin Santra, Chris H. Greene

The interaction of atomic clusters with short, intense pulses of laser light to form extremely hot, dense plasmas has attracted extensive experimental and theoretical interest. The high density of atoms within the cluster greatly enhances the atom--laser interaction, while the finite size of the cluster prevents energy from escaping the interaction region. R

Sankar Das Sarma, Chetan Nayak, Sumanta Tewari

We propose a simple way to stabilize half-quantum vortices in superconducting strontium ruthenate, assuming the order parameter is of chiral $p_x + ip_y$ symmetry, as is suggested by recent experiments. The method, first given by Salomaa and Volovik in the context of Helium-3, is very naturally suited for strontium ruthenate, which has a layered, quasi-two-d

Samir D. Mathur

We give an elementary review of black holes in string theory. We discuss black hole entropy from string microstates and Hawking radiation from these states. We then review the structure of 2-charge microstates, and explore how `fractionation' can lead to quantum effects over macroscopic length scales of order the horizon radius.

Marina Nielsen

We use the QCD sum rules to analize the hadronic decay $D_{sJ}^{+}(2317)\to D_s^+π^0$, in the hypotesis that the $D_{sJ}^{+}(2317)$ can be identified as a four-quark state. We use a diquak-antidiquark current and work to the order of $m_s$ in full QCD, without relying on $1/m_c$ expansion. We find that the partial decay width of the hadronic isospin violatin

Subinoy Das, Pier Stefano Corasaniti, Justin Khoury

We show that an interaction between dark matter and dark energy generically results in an effective dark energy equation of state of w<-1. This arises because the interaction alters the redshift-dependence of the matter density. An observer who fits the data treating the dark matter as non-interacting will infer an effective dark energy fluid with w<-1. We a

Francis Halzen

Lepton Photon 2005 told the saga of the Standard Model which is still exhilarating because it leaves all questions of consequence unanswered.

Stelios Kazantzidis, Andrew R. Zentner, Andrey V. Kravtsov

We present a comprehensive series of dissipationless N-body simulations to investigate the evolution of density distribution in equal-mass mergers between dark matter (DM) halos and multicomponent galaxies. The DM halo models are constructed with various asymptotic power-law indices ranging from steep cusps to core-like profiles and the structural properties

Jonathan B. Foster, Alyssa A. Goodman

We present new deep near-infrared images of dark clouds in the Perseus molecular complex. These images show beautiful extended emission which we model as scattered ambient starlight and name ``cloudshine&#39;&#39;. The brightness and color variation of cloudshine complicates the production of extinction maps, the best tracer of column density in clouds. Howe

Yungui Gong, Anzhong Wang, Yuan-Zhong Zhang

We discuss the phenomenological model in which the potential energy of the quintessence field depends linearly on the energy density of the spatial curvature. We find that the pressure of the scalar field takes a different form when the potential of the scalar field also depends on the scale factor and the energy momentum tensor of the scalar field can be ex

Peter van Loock, Kae Nemoto, William J. Munro, Philippe Raynal

We discuss the problem of implementing generalized measurements (POVMs) with linear optics, either based upon a static linear array or including conditional dynamics. In our approach, a given POVM shall be identified as a solution to an optimization problem for a chosen cost function. We formulate a general principle: the implementation is only possible if a

Edmundo Castillo, Rafael Diaz

We define homological matrices, construct examples of one-dimension restricted homological quantum field theories, and show a relationship between the two theories.

N. Dupuis, C. Bourbonnais, J. C. Nickel

We review the current understanding of superconductivity in the quasi-one-dimensional organic conductors of the Bechgaard and Fabre salt families. We discuss the interplay between superconductivity, antiferromagnetism, and charge-density-wave fluctuations. The connection to recent experimental observations supporting unconventional pairing and the possibilit

U. Gran, P. Lohrmann, G. Papadopoulos

We determine the geometry of supersymmetric heterotic string backgrounds for which all parallel spinors with respect to the connection $\hat\nabla$ with torsion $H$, the NS$\otimes$NS three-form field strength, are Killing. We find that there are two classes of such backgrounds, the null and the timelike. The Killing spinors of the null backgrounds have stab

T. Matsuki, T. Morii, K. Sudoh

Recent discovery of D_sJ particles, which are considered to be a great trouble by experimentalists as well as theorists, had already been resolved by our potential model proposed some time ago by two of us (T.M. and T.M.), in which the Hamiltonian and wave functions are expanded in 1/(heavy quark mass) respecting heavy quark symmetry. Using our model, we exp

Peter Jung

Optimal link adaption to the scattering function of wide sense stationary uncorrelated scattering (WSSUS) mobile communication channels is still an unsolved problem despite its importance for next-generation system design. In multicarrier transmission such link adaption is performed by pulse shaping which in turn is equivalent to precoding with respect to th

Chris Done, Marek Gierlinski

There is growing evidence from both spectral and timing properties that there is a truncated inner accretion disc in low mass accretion rate Galactic black hole systems. The detection of extremely smeared relativistic iron lines in some of these systems is the only current piece of evidence which conflicts with this geometrical interpretation of the low/hard

P. Dendooven, S. Purushothaman, K. Gloos

In-situ purification of the gas used as stopping medium in a noble gas ion catcher by operating the device at low temperatures of 60 to 150 K was investigated. Alpha-decay recoil ions from a 223Ra source served as energetic probes. The combined ion survival and transport efficiencies for 219Rn ions saturated below about 90 K, reaching 28.7(17) % in helium, 2

Tarun Kr. Barik, Partha Roy Chaudhuri, Anushree Roy, Sayan Kar

Surface waves on liquids act as a dynamical phase grating for incident light. In this article, we revisit the classical method of probing such waves (wavelengths of the order of mm) as well as inherent properties of liquids and liquid films on liquids, using optical diffraction. A combination of simulation and experiment is proposed to trace out the surface

B. Sacepe, C. Chapelier, C. Marcenat, J. Kacmarcik

We present the first scanning tunneling spectroscopy study of single-crystalline boron doped diamond. The measurements were performed below 100 mK with a low temperature scanning tunneling microscope. The tunneling density of states displays a clear superconducting gap. The temperature evolution of the order parameter follows the weak coupling BCS law with $

Myriam Gitti, Luigina Feretti, Sabine Schindler

We report on the peculiar activity of the radio source located at the center of the cooling flow cluster RBS797 (z=0.35), the first distant cluster in which two pronounced X-ray cavities have been discovered. New multifrequency (1.4, 4.8, and 8.4 GHz) observations obtained with the Very Large Array clearly reveal the presence of radio emission on three diffe

Harry J. Lipkin, Philip D. Mannheim

Using general properties of the crystal site representation normal mode matrix, we provide some very simple bounds on localized modes in simple, body-centered and face-centered cubic crystals with substitutional point defects. We derive a trace condition constraint on the net change in crystal eigenfrequencies caused by the introduction of a defect, with the

Marcus T. Grisaru, Silvia Penati, Alberto Romagnoni

We present a systematic investigation of one-loop renormalizability for nonanticommutative N=1/2, U(N) SYM theory in superspace. We first discuss classical gauge invariance of the pure gauge theory and show that in contradistinction to the ordinary anticommutative case, different representations of supercovariant derivatives and field strengths do not lead t

Michele Della Morte, Magdalena Luz

We simulate two dimensional QED with two degenerate Wilson fermions and plaquette gauge action. As a consequence of the Mermin-Wagner theorem, in the continuum limit chiral symmetry is realized a la Wigner. This property affects also the size of the cutoff effects. That can be understood in view of the fact that the leading lattice artifacts are described, i

Takao Suyama

We show an explicit relation between an RG flow of a two-dimensional gravity and an on-shell tachyon condensation in the corresponding string theory, in the case when the string theory is supercritical. The shape of the tachyon potential in this case can, in principle, be obtained by examining various RG flows. We also argue that the shape of tachyon potenti

Stefano Capitani

Using the domain-wall formulation of lattice fermions, we have computed the one-loop renormalization factors of one-link operators which measure the first nontrivial moment of the unpolarized, polarized and transversity structure functions, in the flavor nonsinglet sector. The knowledge of these factors is necessary in order to extract physical numbers from

V. K. Magas, L. P. Csernai, E. Molnar

The freeze out of particles from a layer of finite thickness is discussed in a phenomenological kinetic model. The proposed model, based on the Modified Boltzman Transport Equation, is Lorentz invariant and can be applied equally well for the freeze out layers with space-like and time-like normal vectors. It leads to non-equilibrated post freeze out distribu

S. Bertini, S. L. Cacciatori, B. L. Cerchiai

In this paper we reconsider the problem of the Euler parametrization for the unitary groups. After constructing the generic group element in terms of generalized angles, we compute the invariant measure on SU(N) and then we determine the full range of the parameters, using both topological and geometrical methods. In particular, we show that the given parame

G. L. Alberghi, A. Tronconi

We study cosmology in a five-dimensional brane-world with a stabilizing effective potential for the radion and matter localized on the two branes. We consider the corrections induced by the Gauss-Bonnet contribution to the total action performing and expansion around the two possible static solutions up to second order in the ratio between brane matter energ

C. Marquet, C. Royon

We investigate small-x QCD effects in forward-jet production in deep inelastic scattering in the kinematic regime where the virtuality of the photon and the transverse momentum of the jet are two hard scales of about the same magnitude. We show that the data from HERA published by the H1 and ZEUS collaborations are well described by leading-logarithmic BFKL

A. Wronska, V. Hejny, C. Wilkin, S. Dymov

The d+d->alpha+eta reaction has been investigated near threshold using the ANKE facility at COSY-Juelich. Both total and differential cross sections have been measured at two excess energies, Q=2.6 MeV and 7.7 MeV, with a subthreshold measurement being undertaken at Q=-2.6 MeV to study the physical background. While consistent with isotropy at the lower ener

Florian Gmeiner, Ralph Blumenhagen, Gabriele Honecker, Dieter Lust

Continuing our recent work hep-th/0411173, we study the statistics of four-dimensional, supersymmetric intersecting D-brane models in a toroidal orientifold background. We have performed a vast computer survey of solutions to the stringy consistency conditions and present their statistical implications with special emphasis on the frequency of Standard Model

F. Fucito, J. F. Morales, R. Poghossian, A. Tanzini

In this paper we compute gaugino and scalar condensates in N=1 supersymmetric gauge theories with and without massive adjoint matter, using localization formulae over the multi--instanton moduli space. Furthermore we compute the chiral ring relations among the correlators of the $N=1^*$ theory and check this result against the multi-instanton computation fin

Mehmet Koca, Ramazan Koc, Muataz Al-Barwani

Cayley-Dickson doubling procedure is used to construct the root systems of some celebrated Lie algebras in terms of the integer elements of the division algebras of real numbers, complex numbers, quaternions and octonions. Starting with the roots and weights of SU(2) expressed as the real numbers one can construct the root systems of the Lie algebras of SO(4

Paul Gartner, Jan Seebeck, Frank Jahnke

The time evolution of optically excited carriers in semiconductor quantum wells and quantum dots is analyzed for their interaction with LO-phonons. Both the full two-time Green&#39;s function formalism and the one-time approximation provided by the generalized Kadanoff-Baym ansatz are considered, in order to compare their description of relaxation processes.

Sandhya Choubey, Kamales Kar

We use the detection of neutrinos from a future galactic type-II supernova event in a water Cerenkov detector like Super-Kamiokande to constrain the possible violation of spin-statistics by neutrinos resulting in their obeying a mixed statistics instead of Fermi-Dirac.

Arnaud Bodin

We prove a analogous of Stein theorem for rational functions in several variables: we bound the number of reducible fibers by a formula depending on the degree of the fraction.

Joan Porti, Hartmut Weiss

Given a closed orientable Euclidean cone 3-manifold C with cone angles less than or equal to pi, and which is not almost product, we describe the space of constant curvature cone structures on C with cone angles less than pi. We establish a regeneration result for such Euclidean cone manifolds into spherical or hyperbolic ones and we also deduce global rigid

Jan Ambjorn, Romuald A. Janik, Charlotte Kristjansen

Assuming that the world-sheet sigma-model in the AdS/CFT correspondence is an integrable {\em quantum} field theory, we deduce that there might be new corrections to the spin-chain/string Bethe ansatz paradigm. These come from virtual particles propagating around the circumference of the cylinder and render Bethe ansatz quantization conditions only approxima

Morteza Mohseni

We study the motion of a pseudo-classical charged particle with spin in the space-time of a gravitational pp wave in the presence of a uniform magnetic field.

Charles Hellaby, Andrzej Krasinski

We describe several new ways of specifying the behaviour of Lemaitre-Tolman (LT) models, in each case presenting the method for obtaining the LT arbitrary functions from the given data, and the conditions for existence of such solutions. In addition to our previously considered `boundary conditions&#39;, the new ones include: a simultaneous big bang, a homog

Emmanuel Royer

We provide a systematic method to compute arithmetic sums including some previously computed by Alaca, Alaca, Besge, Cheng, Glaisher, Huard, Lahiri, Lemire, Melfi, Ou, Ramanujan, Spearman and Williams. Our method is based on quasimodular forms. This extension of modular forms has been constructed by Kaneko andZagier.

Duncan Forbes, Patricia Sanchez-Blazquez, Anna Phan, Jean Brodie

We present wide-field Keck telescope imaging of the globular cluster (GC) systems around NGC 1407 and NGC 1400 in the Eridanus galaxy cloud. This is complemented by Hubble Space Telescope images from the Advanced Camera for Surveys of NGC 1407 and Wide Field and Planetary Camera 2 images of NGC 1400. We clearly detect bimodality in the GC colour distribution

Jeong-Yup Lee

The paper establishes an equivalence between pure point diffraction and certain types of model sets, called inter model sets, in the context of substitution point sets and substitution tilings. The key ingredients are a new type of coincidence condition in substitution point sets, which we call algebraic coincidence, and the use of a recent characterization

Takeshi Chiba

Important observables to reveal the nature of dark energy are the equation of state $w$ and its time derivative in units of the Hubble time $w&#39;$. Recently, it is shown that the simplest scalar field models of dark energy (quintessence) occupy rather narrow regions in the $w-w&#39;$ plane. We extend the $w-w&#39;$ plane to $w<-1$ and derive bounds on $w&#

M. A. Reyes, H. C. Rosu

It has been proven by Rosu and Cornejo-Perez in 2005 that for some nonlinear second-order ODEs it is a very simple task to find one particular solution once the nonlinear equation is factorized with the use of two first-order differential operators. Here, it is shown that an interesting class of parametric solutions is easy to obtain if the proposed factoriz

Sandra S. Padula, Y. Hama, G. Krein, P. K. Panda

Back-to-Back Correlations (BBC) of particle-antiparticle pairs are predicted to appear if hot and dense hadronic matter is formed in high energy nucleus-nucleus collisions. The BBC correlations are related to in-medium mass-modification and squeezing of the quanta involved. The formalisms are analogous in the bosonic (bBBC) and in the fermionic (fBBC) cases.

Massimiliano Esposito, Fritz Haake

A quantum system weakly interacting with a fast environment usually undergoes a relaxation with complex frequencies whose imaginary parts are damping rates quadratic in the coupling to the environment, in accord with Fermi&#39;s ``Golden Rule&#39;&#39;. We show for various models (spin damped by harmonic-oscillator or random-matrix baths, quantum diffusion,

Marcel Novaes

We study the dynamical generation of entanglement for a very simple system: a pair of interacting spins, s1 and s2, in a constant magnetic field. Two different situations are considered:(a) s1 ->\infty, s2 = 1/2 and (b) s1 = s2 ->\infty, corresponding, respectively, to a quantum degree of freedom coupled to a semiclassical one (a qubit in contact with an env

Mark Hillery, Mario Ziman, Vladimir Buzek

A quantum processor is a programmable quantum circuit in which both the data and the program, which specifies the operation that is carried out on the data, are quantum states. We study the situation in which we want to use such a processor to approximate a set of unitary operators to a specified level of precision. We measure how well an operation is perfor