July 2003 arXiv papers — page 10

G. Biroli, O. Parcollet, G. Kotliar

Cluster Dynamical Mean Field Theories are analyzed in terms of their semiclassical limit and their causality properties, and a translation invariant formulation of the cellular dynamical mean field theory, PCDMFT, is presented. The semiclassical limit of the cluster methods is analyzed by applying them to the Falikov-Kimball model in the limit of infinite Hu

A. Crisanti, L. Leuzzi, T. Rizzo

Some questions concerning the calculation of the number of ``physical'' (metastable) states or complexity of the spherical $p$-spin spin glass model are reviewed and examined further. Particular attention is focused on the general calculation procedure which is discussed step-by-step.

J. Ruostekoski, T. Gasenzer, D. A. W. Hutchinson

We theoretically study a pulsed stimulated two-photon Raman outcoupler for an atom laser using a full three-dimensional description. A finite-temperature trapped Bose-condensed atomic gas is treated self-consistently by the Hartree-Fock-Bogoliubov equations. The model is closely related to a recent experiment on optical outcoupling [E.W. Hagley et al., Scien

Oscar Iglesias, Amilcar Labarta

We present the results of Monte Carlo simulations of a model of a single maghemite ferrimagnetic nanoparticle including radial surface anisotropy distinct from that in the core with the aim to clarify what is its role on the magnetization processes at low temperatures. The low temperature equilibrium states are analized and compared to those of a ferromagnet

J. J. Tu, C. C. Homes, L. H. Greene, G. D. Gu

The optical properties of optimally-doped Bi_2Sr_2CaCu_2O_{8+δ} (Bi2212) have been measured normal to the edge planes [ac plane, bc plane, and (1\bar{1}0) plane], for light polarized parallel to nodal and anti-nodal (gap) directions, respectively. While the superfluid contribution can be obtained from the optical conductivities in the (1\bar{1}0)-plane, it i

J. C. Kim, David G. Cahill, R. S. Averback

Nanocavities in Ge(111) created by 5 keV Xe ion irradiation are characterized by ex situ transmission electron microscopy and Rutherford backscattering spectrometry. Nanocavities nucleate near the surface and then undergo thermal migration. Nanocavities with average diameter of 10 nm and areal density of 5.1 x 10-3 nm-2 are observed at 773 K, while nanocavit

M. Mercedes Calbi, Ari Mizel, Milton W. Cole

We explore the ground state of a single hydrogen molecule within an interstitial channel (IC) of a bundle of carbon nanotubes. A previous (variational) study found that when many molecules are present, comprising a dense fluid, the nanotube lattice is slightly dilated, with a 1% relative increase of lattice constant. Although small, that dilation doubled the

Barbara Drossel, Mehran Kardar

We study the interplay between surface roughening and phase separation during the growth of binary films. Renormalization group calculations are performed on a pair of equations coupling the interface height and order parameter fluctuations. We find a larger roughness exponent at the critical point of the order parameter compared to the disordered phase, and

Natan Andrei, Efrat Shimshoni, Achim Rosch

We outline a general approach to the computation of transport properties of interacting systems at low temperetures and frequencies. We show that if the fixed point and the irrelevant operators around it are known, then by studying the structure of the softly violated conserved currents chracterizing the fixed point one may set up an effective calculation in

Lorenzo Bongini, Roberto Livi, Alessandro Torcini, Antonio Politi

Jumps between neighboring minima in the energy landscape of both homopolymeric and heteropolymeric chains are numerically investigated by determining the average escape time from different valleys. The numerical results are compared to the theoretical expression derived by Langer [J.S. Langer, Ann. Phys. 54 (1969) 258] with reference to a 2N-dimensional spac

L. H. Yu, D. Natelson

We report the first low temperature magnetotransport measurements on electrochemically fabricated atomic scale gold nanojunctions. As $T \to 0$, the junctions exhibit nonperturbatively large zero bias anomalies (ZBAs) in their differential conductance. We consider several explanations and find that the ZBAs are consistent with a reduced local density of stat

R. J. Radwanski, Z. Ropka

We point out that the orbital magnetism has to be taken into account in the description of real 3d-ion compounds. According to the developed by us the Quantum-Atomistic Solid-State (QUASST) theory in compounds containing open 3d-/4f-/5f-shell atoms there exists a discrete atomic-like low-energy electronic structure that predominantly determines electronic an

Marconi Soares Barbosa, Luciano da Fontoura Costa, Esmerindo de Sousa Bernardes

This work presents a procedure to extract morphological information from neuronal cells based on the variation of shape functionals as the cell geometry undergoes a dilation through a wide interval of spatial scales. The targeted shapes are alpha and beta cat retinal ganglion cells, which are characterized by different ranges of dendritic field diameter. Ima

Tomasz Dietl

An overview of recent studies on ferromagnetism in Cr- and Mn-based II-VI diluted magnetic semiconductors is presented emphasizing differences in underlying exchange mechanisms. Examples of manipulations with spin ordering by carrier density, dimensionality, light, and electric field are given.

J. Heinrichs

The cumulants of the logarithm of the conductance (lng) in the localized regime in the one-dimensional Anderson model are calculated exactly in the second Born approximation for weak disorder. Only the first two cumulants turn out to ne non-zero since the third and fourth cumulants vanish identically and the higher cumulants are of higher order in the disord

J. Heinrichs

We obtain for the first time the expressions for the mean and the variance of the transmission coefficient for an Anderson chain in the weak localization regime, using exact expansions of the complex transmission- and reflection coefficients to fourth order in the weakly disordered site energies. These results confirm the validity of single-parameter scaling

J. Heinrichs

This paper extends an earlier analytical scattering matrix treatment of conductance and localization in coupled two- and three Anderson chain systems for weak disorder when evanescent states are present at the Fermi level. Such states exist typically when the interchain coupling exceeds the width of propagating energy bands associated with the various transv

L. Y. Gorelik, S. I. Kulinich, R. I. Shekhter, M. Jonson

We consider the microwave dynamics and transport properties of a voltage-biased single-Cooper-pair transistor. The dynamics is shown to be strongly affected by interference between multiple microwave-induced inter-level transitions. As a result the magnitude and direction of the dc Josephson current are extremely sensitive to small variations of the bias vol

G. J. Ackland

We investigate whether the equilibrium time averaged state of a self-organising system with many internal degrees of freedom, 2D- daisyworld, can be described by optimising a single quantity. Unlike physical systems where a principle of maximum energy production has been observed, Daisyworld follows evolutionary dynamics rather than Hamiltonian dynamics. We

Jorge A. Revelli, Carlos. E. Budde, Horacio S. Wio

We present a one-dimensional model for diffusion in a fluctuating lattice; that is a lattice which can be in two or more states. Transitions between the lattice states are induced by a combination of two processes: one periodic deterministic and the other stochastic. We study the dynamics of a system of particles moving in that medium, and characterize the p

K. Bittkau, Ch. Menk, Ch. Heyn, D. Heitmann

We present far-infrared (FIR) photo-conductivity measurements for a two-dimensional electron gas in an array of nano-structured antidots. We detect, resistively and spectrally resolved, both the magnetoplasmon and the edge-magnetoplasmon modes. Temperature-dependent measurements demonstrates that both modes contribute to the photo resistance by heating the e

Ryusuke Ikeda

We examine the idea, postulated by Phillips et al., that a finite resistivity in $T \to 0$ limit in disordered granular superconducting (SC) films is explained as a consequence of the absence of phase stiffness in a phase glass (PG) peculiar to granular systems. It is found that a coupling between the nonzero PG order and the ordinary SC fluctuation makes th

Matthias Sperl

The slow dynamics for a colloidal suspension of particles interacting with a hard-core repulsion complemented by a short-ranged attraction is discussed within the frame of mode-coupling theory for ideal glass transitions for parameter points near a higher-order glass-transition singularity. The solutions of the equations of motion for the density correlation

Carsten Russ, Klaus Zahn, Hans-Hennig von Grunberg

Three-body distribution functions in classical fluids have been theoretically investigated many times, but have never been measured directly. We present experimental three-point correlation functions that are computed from particle configurations measured by means of video-microscopy in two types of quasi-two-dimensional colloidal model fluids: a system of c

Max A. Metlitski, Ariel R. Zhitnitsky

We study the structure of the vortex core in two-component Bose-Einstein condensates. We demonstrate that the order parameter may not vanish and the symmetry may not be restored in the core of the vortex. In this case such vortices can form vortex rings known as vortons in particle physics literature. In contrast with well-studied superfluid $^4He$, where si

J. -Y. Chen, W. Cox, E. Tehan, F. V. Bright

A number of researchers are attempting to develop a biosensor based on terahertz sensing. Key to the realization of any biosensor system is the access of the target molecules to the sensor. In the case of using terahertz spectroscopy, there are limitations due to high attenuation by water and sensitivity levels. In order to have a significant response at THz

J. -Y. Chen, J. Cerne, A. G. Markelz

We propose a biosensor based on the change of terahertz (THz) dielectric response when a biotarget binds to a probe. The feasibility of this biosensor is examined by studying the change of THz transmission for thin films of heme proteins myoglobin (Mb) and cytochrome C (CytC) as a function oxygen binding. We measure a strong increase in both the index and ab

H. F. Chau, F. K. Chow, K. H. Ho

To study the interplay between global market choice and local peer pressure, we construct a minority-game-like econophysical model. In this so-called networked minority game model, every selfish player uses both the historical minority choice of the population and the historical choice of one's neighbors in an unbiased manner to make decision. Results of

Lou Kondic, R. P. Behringer

We probe, using a model system, elastic and kinetic energies for sheared granular materials. For large enough $P/E_y$ (pressure/Young's modulus) and $P/ρv^2$ ($P/$kinetic energy density) elastic dominates kinetic energy, and energy fluctuations become primarily elastic in nature. This regime has likely been reached in recent experiments. We consider a ge

A. Crisanti, F Ritort

We consider heat exchange processes between non-equilibrium aging systems (in their activated regime) and the thermal bath in contact. We discuss a scenario where two different heat exchange processes concur in the overall heat dissipation: a stimulated fast process determined by the temperature of the bath and a spontaneous intermittent process determined b

Kazuhiko Kuroki, Yukio Tanaka, Takashi Kimura, Ryotaro Arita

To shed light into the pairing mechanism of possible spin-triplet superconductors (TMTSF)$_2$X and Sr$_2$RuO$_4$, we study the competition among various spin singlet and triplet pairing channels in the Hubbard model by calculating the pairing interaction vertex using the ground state quantum Monte Carlo technique. We model (TMTSF)$_2$X by a quarter-filled qu

D. N. Tsigankov, E. Pazy, B. D. Laikhtman, A. L. Efros

Using numerical simulations we studied the long time relaxation of the hopping conductivity. Even though no modern computation is able to simulate the behavior of a large size system over minutes or hours so as to observe the relaxation, still we have been able to show that the long time relaxation and aging effect observed in experiments can be explained in

C. L. Yuan, Z. Y. Zeng, Y. Zhu, P. P. Ong

We investigate the temperature dependence of the resistivity and magnetoresistance of a polycrystalline $Sr_2CoMoO_{6-δ}$ film deposited on (100)-$SrTiO_3$ substrate prepared by the pulsed laser deposition method. X-ray diffraction, Raman and magnetoresistance results demonstrate clearly the coexistence of a ferromagnetic metallic and an antiferromagnetic (o

G. D. Sanders, Y. Sun, F. V. Kyrychenko, C. J. Stanton

We present a theory for electronic and magneto-optical properties of n-type In(1-x)Mn(x)As magnetic alloy semiconductors in a high magnetic field, B. We use an 8-band Pidgeon-Brown model generalized to include the wavevector (Kz) dependence of the electronic states as well as s-d and p-d exchange interactions with localized Mn d-electrons. Calculated conduct

Ernesto Villar-Cocina, Eduardo Valencia-Morales, Jesus Hernandez-Ruiz, Jorge Vega-Leyva

We study the kinetics of absorption of water in portland cement mortars added with 60, 70 and 80% of granulated blast furnace slag (GGBS or Slag) cured in water and at open air and preheating at 50 and 100 C.A mathematical model is presented that allows describing the process not only in early ages where the capillary sorption is predominant but also for lat

Jin H. An, K. Sellgren

We present a new 0.9" resolution 3.29 micron narrowband image of the reflection nebula NGC 7023. We find that the 3.29 micron IEF in NGC 7023 is brightest in narrow filaments NW of the illuminating star. These filaments have been seen in images of K', molecular hydrogen emission lines, the 6.2 and 11.3 micron IEFs, and HCO+. We also detect 3.29 micro

Hiranya V. Peiris, Scott Tremaine

We construct dynamical models of the ``double'' nucleus of M31 in which the nucleus consists of an eccentric disk of stars orbiting a central black hole. The principal approximation in these models is that the disk stars travel in a Kepler potential, i.e., we neglect the mass of the disk relative to the black hole. We consider both ``aligned'&#39

D. Falceta-Goncalves, V. Jatenco-Pereira, M. de Juli

It has been shown that magnetic fields play an important role in the stability of molecular clouds, mainly perpendicularly to the field direction. However, in the parallel direction the stability is a serious problem still to be explained. Interstellar turbulence may allow the generation of Alfvén waves that propagate through the clouds in the magnetic field

Fabian Walter, Frank Bertoldi, Chris Carilli, Pierre Cox

Observations of the molecular gas phase in quasar host galaxies provide fundamental constraints on galaxy evolution at the highest redshifts. Molecular gas is the material out of which stars form; it can be traced by spectral line emission of carbon--monoxide (CO). To date, CO emission has been detected in more than a dozen quasar host galaxies with redshift

Terry J. Jones

Interstellar polarization from aligned dust grains can be measured both in transmission at visible and near-infrared wavelengths and in emission at far-infrared and sub-mm wavelengths. These observations can help predict the behavior of foreground contamination of CMB polarimetry by dust in the Milky Way. Fractional polarization in emission from aligned dust

F. Bertoldi, P. Cox, R. Neri, C. L. Carilli

We report the detection of high excitation CO emission from the most distant quasar currently known, SDSS J114816.64+525150.3 (hereafter J1148+5251), at a redshift z=6.419. The CO (J=6-5) and (J=7-6) lines were detected using the IRAM Plateau de Bure interferometer, showing a width of ~280 km/s. An upper flux limit for the CO (J=1-0) line was obtained from o

Olivier Chesneau, Sebastian Wolf, Armando Domiciano de Souza

We present a prospective work undertaken on Spectro-Polarimetric INterferometry (SPIN). Our theoretical studies suggest that SPIN is a powerful tool for studying the mass loss from early type stars. Based on Monte Carlo simulations, we computed the expected SPIN signal for numerous hot star spectral types covering a broad range of geometries and optical dept

D. Gotz, S. Mereghetti, K. Hurley, S. Deluit

A long Gamma-Ray Burst (GRB) was detected with the instruments on board the INTEGRAL satellite on January 31 2003. Although most of the GRB, which lasted $\sim$150 seconds, occurred during a satellite slew, the automatic software of the INTEGRAL Burst Alert System was able to detect it in near-real time. Here we report the results obtained with the IBIS inst

R. I. Davies, A. Sternberg, M. Lehnert, L. E. Tacconi-Garman

We report medium resolution VLT ISAAC K-band spectroscopy of the nuclei of seven ultraluminous infrared galaxies. After accounting for stellar absorption features, we have detected several molecular hydrogen (H_2) v=1-0, 2-1, and 3-2 vibrational emission lines, as well as the HI Brγand HeI 2^1P-2^1S recombination lines. The relative H_2 line intensities show

Markos Georganopoulos, Demosthenes Kazanas

TeV emission from BL Lacertae (BL) objects is commonly modeled as Synchrotron-Self Compton (SSC) radiation from relativistically moving homogeneous plasma blobs. In the context of these models, the blob Lorentz factors needed to reproduce the corrected for absorption by the diffuse IR background (DIRB) TeV emission are large ($δ\gtrsim 50$). The main reason

R. Bernabei, P. Belli, F. Cappella, R. Cerulli

Main arguments on the Dark Matter particle direct detection approach are addressed on the basis of the work and of the results of the about 100 kg highly radiopure NaI(Tl) DAMA experiment (DAMA/NaI), which has been operative at the Gran Sasso National Laboratory of the I.N.F.N. for more than one decade, including the preparation. The effectiveness of the WIM

J. R. Brucato, G. Strazzulla, G. Baratta, L. Colangeli

We present experimental results on crystal--amorphous transition of forsterite (Mg2SiO4) silicate under ion irradiation. The aim of this work is to study the structural evolution of one of the most abundant crystalline silicates observed in space driven by ion irradiation. To this aim, forsterite films have been sythesised in laboratory and irradiated with l

Alexei Y. Kniazev, Eva K. Grebel, Lei Hao, Michael A. Strauss

We report the discovery of eight new extremely metal-poor galaxies (XMPGs; 12+log(O/H) < 7.65) and the recovery of four previously known or suspected XMPGs (IZw18, HS0822+3542, HS0837+4717 and A1116+517) using Sloan Digital Sky Survey (SDSS) spectroscopy. These new objects were identified after an analysis of 250,000 galaxy spectra within an area of ~3000 de

P. E. Hardee

Many jets exhibit twisted helical structures. Where superluminal motions are detected, jet orientation and pattern/flow speed are considerably constrained. In this case modeling efforts can place strong limits on conditions in the jet and in the external environment. This can be done by modeling the spatial development of helical structures which are sensiti

E. Momjian, J. D. Romney, C. L. Carilli, T. H. Troland

We present phase-referenced VLBI observations of the radio continuum emission from, and the H I 21 cm absorption toward, the Luminous Infrared Galaxy NGC 7674. The observations were carried out at 1380 MHz using the VLBA, the phased VLA, and theArecibo radio telescope. These observations constitute the first scientific use of the Arecibo telescope in a VLBI

Stelios Kazantzidis, Ben Moore, Lucio Mayer

The Ultra Compact Dwarf (UCD) galaxies recently discovered in the Fornax and Virgo clusters exhibit structural similarity to the dense nuclei of nucleated dEs indicating that the progenitor galaxy and its halo have been entirely tidally disrupted. Using high resolution $N$-body simulations with up to ten million particles we investigate the evolution and tid

Ya. I. Azimov, R. A. Arndt, I. I. Strakovsky, R. L. Workman

The problem of nucleon resonances N&#39; with masses below the Delta is considered. We derive bounds for the properties of such states. Some of these are new, while others improve upon existing limits. We discuss the nature of N&#39; states, and their unitary partners, assuming their existence can be verified.

Joel Giedt, Brent D. Nelson

We discuss duality between the linear and chiral dilaton formulations, in the presence of super-Yang-Mills instanton corrections to the effective action. In contrast to previous work on the subject, our approach appeals directly to explicit instanton calculations and does not rely on the introduction of an auxiliary Veneziano-Yankielowicz superfield. We disc

D. Huber, L. S. Tsimring

The dynamics of an ensemble of bistable elements with global time-delayed coupling under the influence of noise is studied analytically and numerically. Depending on the noise level the system undergoes ordering transitions and demonstrates multi-stability. That is, for a strong enough positive feedback it exhibits a non-zero stationary mean field and a vari

Brandon C. Kelly, Timothy A. McKay

We describe application of the `shapelet&#39; linear decomposition of galaxy images to morphological classification using images of $\sim$ 3000 galaxies from the Sloan Digital Sky Survey. After decomposing the galaxies we perform a principal component analysis to reduce the number of dimensions of the shapelet space to nine. We find that each of these nine p

M. Jarvis, G. Bernstein, B. Jain

We present simple formulae for calculating the skewness and kurtosis of the aperture mass statistic for weak lensing surveys which is insensitive to masking effects of survey geometry or variable survey depth. The calculation is the higher order analog of the formula given by Schneider et al (2002) which has been used to compute the variance of the aperture

J. M. Miller, J. Raymond, A. C. Fabian, J. Homan

We observed the Galactic black hole GX 339-4 with the Chandra High Energy Transmission Grating Spectrometer (HETGS) for 75 ksec during the decline of its 2002-2003 outburst. The sensitivity of this observation provides an unprecedented glimpse of a Galactic black hole at about a tenth of the luminosity of the outburst peak. The continuum spectrum is well des

Alessandro Bacchetta, Andreas Metz, Jian-Jun Yang

We estimate the Collins fragmentation function by introducing the effect of gluon rescattering in a model calculation of the fragmentation process. We include all necessary diagrams to the one-loop level and compute the nontrivial phases giving rise to the Collins function. We compare our results to the ones obtained from pion rescattering. We conclude that

Tetsufumi Hirano, Yasushi Nara

We analyze the recent data from the BRAHMS Collaboration on the pseudorapidity dependence of nuclear modification factors in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV by using the full three dimensional hydrodynamic simulations for the density effects on parton energy loss. We first compute the transverse spectra at $η=0$ and 2.2, and next take a ratio $

V. Gayral

Modulo some natural generalizations to noncompact spaces, we show in this letter that Moyal planes are nonunital spectral triples in the sense of Connes. The action functional of these triples is computed, and we obtain the expected result, ie the noncommutative Yang-Mills action associated with the Moyal product. In particular, we show that Moyal gauge theo

A. Crisanti, L. Leuzzi, G. Parisi, T. Rizzo

We study the quenched complexity in spin-glass mean-field models satisfying the Becchi-Rouet-Stora-Tyutin supersymmetry. The outcome of such study, consistent with recent numerical results, allows, in principle, to conjecture the absence of any supersymmetric contribution to the complexity in the Sherrington-Kirkpatrick model. The same analysis can be applie

Manuel Arrayas, Ute Ebert

We recently have proposed that a reduced interfacial model for streamer propagation is able to explain spontaneous branching. Such models require regularization. In the present paper we investigate how transversal Fourier modes of a planar ionization front are regularized by the electric screening length. For a fixed value of the electric field ahead of the

Xiao-Jun Wang, Sen Hu

We study adding flavors into the Maldacena-N\u{u}nez background. It is achieved by introducing spacetime filling D9-branes or intersecting D5$'$-branes into the background with a wrapping D5-brane. Both D9-branes and D5$'$-branes can be spacetime filling from the 5D bulk point of view. At the probe limit it corresponds to introducing non-chiral fundamental f

A. Viale, M. Vicari, N. Zanghi&#39;

We provide a self-contained quantum description of the interference produced by macromolecules diffracted by a grating, with particular reference to fullerene interferometry experiments. We analyze the processes inducing loss of coherence consisting in beam preparation (collimation setup and thermal spread of the wavelengths of the macromolecules) and in env

Apostolos Dimitriadis, Simon F. Ross

We study the supergravity solutions describing non-extremal enhancons. There are two branches of solutions: a `shell branch&#39; connected to the extremal solution, and a `horizon branch&#39; which connects to the Schwarzschild black hole at large mass. We show that the shell branch solutions violate the weak energy condition, and are hence unphysical. We in

Bo-Sture K. Skagerstam, Bjorn A. Bergsjordet

In papers by Lynch [Phys. Rev. A41, 2841 (1990)] and Gerry and Urbanski [Phys. Rev. A42, 662 (1990)] it has been argued that the phase-fluctuation laser experiments of Gerhardt, Büchler and Lifkin [Phys. Lett. 49A, 119 (1974)] are in good agreement with the variance of the Pegg-Barnett phase operator for a coherent state, even for a small number of photons.

Zhuo Li, Z. G. Dai, T. Lu

The shock model has successfully explained the observed behaviors of afterglows from long gamma-ray bursts (GRBs). Here we use it to investigate the so-called early afterglows from short GRBs, which arises from blast waves that are not decelerated considerably by their surrounding medium. We consider a nearby medium loaded with $e^{\pm}$ pairs (Beloborodov 2

Ryuichi Takahashi, Takashi Nakamura

It may be possible to construct a laser interferometer gravitational wave antenna in space with $h_{rms}\sim 10^{-23}$ at $ f\sim 0.1{\rm Hz}$ in $\sim 2020$. This deci hertz antenna may be called DECIGO/BBO,which stand for DECi hertz Interferometer Gravitational wave Observatory and Big Bang Observer, respectively. The analysis of 1-10 years observational d

R. Aloisio, V. Berezinsky, M. Kachelriess

We present results from two different methods for the calculation of hadron spectra in QCD and SUSY QCD with large primary energies $\sqrt{s}$ up to $10^{16}$ GeV. The two methods considered are a Monte Carlo (MC) simulation and the evolution of fragmentation functions described by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations. We find tha

Ian Hambleton, Mihail Tanase

We use the equivariant Yang-Mills moduli space to investigate the relation between the singular set, isotropy representations at fixed points, and permutation modules realized by the induced action on homology for smooth group actions on certain 4-manifolds.

E. Artal, J. Carmona, J. I. Cogolludo, M. Marco

We prove the existence of complexified real arrangements with the same combinatorics but different embeddings in the complex projective plane. Such pair of arrangements has an additional property: they admit conjugated equations on the ring of polynomials over the number field ${\mathbb Q}(\sqrt{5})$.

Y. Bugoslavsky, Y. Miyoshi, G. K. Perkins, A. D. Caplin

Double-gap superconductivity in an epitaxial MgB2 film has been studied by means of point-contact spectroscopy in magnetic field up to 8 Tesla. The relatively fast disappearance of the feature associated with the pi-band gap at a field around 1 T is caused by the line broadening due to strong pair breaking rather than to a collapse of the double-gap state. T

L. Viverit, S. Giorgini, L. P. Pitaevskii, S. Stringari

Using a scattering length parametrization of the BCS-BEC crossover as well as the local density approximation for the density profile, we calculate the momentum distribution of a harmonically trapped atomic Fermi gas at zero temperature. Various interaction regimes are considered, including the BCS phase, the unitarity limit and the molecular regime. We show

H. Sekiya, M. Minowa, Y. Shimizu, Y. Inoue

It is known that scintillation efficiency of organic single crystals depends on the direction of nuclear recoils relative to crystallographic axes. This property could be applied to the directional WIMP dark matter detector. The scintillation efficiency of carbon recoils in a stilbene crystal was measured for recoil energies of 30 keV to 1 MeV using neutrons

Omer F. Dayi

A general solution of the Batalin-Vilkovisky master equation was formulated in terms of generalized fields. Recently, a superfields approach of obtaining solutions of the Batalin-Vilkovisky master equation is also established. Superfields formalism is usually applied to topological quantum field theories. However, generalized fields method is suitable to fin

S. R. Choudhury, A. S. Cornell, Naveen Gaur, G. C. Joshi

Leptonic and semi-leptonic rare decays of B-mesons are very clean (both theoretically and experimentally) signatures of any new physics beyond the Standard Model (SM). More specifically the decay \btokll has been theoretically observed to be very sensitive to new physics as the Forward Backward (FB) asymmetry in this decay mode vanishes in the SM. Supersymme

M. C. Gonzalez, A. O. Sousa, H. J. Herrmann

The Sznajd model of socio-physics, that only a group of people sharing the same opinion can convince their neighbors, is applied to a scale-free random network modeled by a deterministic graph. We also study a model for elections based on the Sznajd model and the exponent obtained for the distribution of votes during the transient agrees with those obtained

Mees de Roo, Martijn G. C. Eenink

We construct the derivative corrections to the four-point vertices in the abelian open string effective action to all orders in alpha&#39;. The result is based on the structure of the string four-point function. Supersymmnetry of these vertices is guaranteed by the supersymmetry of the F^4 term in the effective action. By this construction we establish the e

R. Maiolino, A. Comastri, R. Gilli, N. M. Nagar

A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically &#34;elusive&#34;. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive AGN in

P. J. Heslop, P. S. Howe

The properties of gauge-invariant composite operators and their correlation functions in N=4 SYM are discussed in the analytic superspace formalism. A complete classification of the different types of operators in the theory is given. Operators can be either protected or unprotected according to whether they do not or do have anomalous dimensions, and the an

Alberto Romagnoni

In this letter we use the spurion field approach adopted in hep-th/0307099 in order to show that by adding F and F^2 terms to the original lagrangian, the N=1/2 Wess-Zumino model is renormalizable to all orders in perturbation theory. We reformulate in superspace language the proof given in the recent work hep-th/0307165 in terms of component fields.

S. R. Choudhury, A. S. Cornell, G. C. Joshi, B. H. J. McKellar

In this paper we shall study the phenomenology of a doubly charged and neutral exchange black hole in an $(n+3)$ extra-dimensional scenario, where the black hole shall be treated a normal quantum field.

Ambar Jain, Satish D. Joglekar

We study the causality violation in the non-local phi ^{4}-theory (as formulated by Kleppe and Woodard) containing a finite mass scale Lambda . Starting from the Bogoliubov-Shirkov criterion for causality, we construct and study combinations of S-matrix elements that signal the violation of causality in the one loop approximation. We find that the causality

Andreas Wensauer, Ulrich Rössler

In this paper we present a new approach how to extract polarization-dependent exchange-correlation energy densities for two-dimensional systems from reference densities and energies of quantum dots provided by exact diagonalization. Compared with results from literature we find systematic corrections for all polarizations in the regime of high densities.

Stefanie Russ

We study the localization volumes $V$ (participation ratio) of electronic wave functions in the 2d-Anderson model with diagonal disorder. Using a renormalization procedure, we show that at the band edges, i.e. for energies $E\approx \pm 4$, $V$ is inversely proportional to the variance $\var$ of the site potentials. Using scaling arguments, we show that in t

Mei Huang, Igor Shovkovy

We present a detailed study of the recently proposed gapless color superconductivity in neutral two-flavor quark matter in beta-equilibrium at zero as well as at finite temperature. We clarify the nature of the fermionic quasiparticles, and discuss the physical properties of this gapless phase of quark matter. The appearance of two &#34;secondary&#34; spin-1

Tohru Okamoto, Mitsuaki Ooya, Kunio Hosoya, Shinji Kawaji

We have studied the magnetic and transport properties of an ultra-low-resistivity two-dimensional electron system in a Si/SiGe quantum well. The spin polarization increases linearly with the in-plane magnetic field and the enhancement of the spin susceptibility is consistent with that in Si-MOS structures. Temperature dependence of resistivity remains metall

P. -E. Roche, B. Castaing, B. Chabaud, B. Hebral

A Rayleigh-Bénard cell has been designed to explore the Prandtl (Pr) dependence of turbulent convection in the cross-over range $0.7<Pr<21$ and for the full range of soft and hard turbulences, up to Rayleigh number $Ra\simeq 10^{11}$. The set-up benefits from the favourable characteristics of cryogenic helium-4 in fluid mechanics, in-situ fluid property meas

Mushtaq Loan, Chris Hamer

A comprehensive analysis of the Symanzik improved anisotropic three-dimensional U(1) lattice gauge theory in the Hamiltonian limit is made. Monte Carlo techniques are used to obtain numerical results for the static potential, ratio of the renormalized and bare anisotropies, the string tension, lowest glueball masses and the mass ratio. Evidence that rotation

A. E. Kaloshin, V. P. Lomov

We obtain in analytical form the dressed propagator of the Rarita-Schwinger field taking into account all spin components and discuss shortly its properties.

M. Asoudeh, V. Karimipour, L. Memarzadeh, A. T. Rezakhani

We analyze a recent suggestion \cite{kauffman1,kauffman2} on a possible relation between topological and quantum mechanical entanglements. We show that a one to one correspondence does not exist, neither between topologically linked diagrams and entangled states, nor between braid operators and quantum entanglers. We also add a new dimension to the question

Argyro Tasitsiomi, Jennifer Gaskins, Angela V. Olinto

We calculate the expected flux of gamma-ray and radio emission from the LMC due to neutralino annihilation. Using rotation curve data to probe the density profile and assuming a minimum disk, we describe the dark matter halo of the LMC using models predicted by N-body simulations. We consider a range of density profiles including the NFW profile, a modified

Richard A. Mould

The author has proposed five rules that permit conscious observers to be included in quantum mechanics. In the present paper, these rules are applied to the observation of a non-local pair of correlated particles. Rule (4) again prevents an anomalous result. Two different kinds of relativistic state reduction are considered, where these differ in the way tha

B. F. Samsonov, A. A. Pecheritsin, E. O. Pozdeeva, M. L. Glasser

A new exactly solvable relativistic periodic potential is obtained by the periodic extension of a well-known transparent scalar potential. It is found that the energy band edges are determined by a transcendental equation which is very similar to the corresponding equation for the Dirac Kronig-Penney model. The solutions of the Dirac equation are expressed i

Barbara Kraus, J. Ignacio Cirac

We show how one can entangle distant atoms by using squeezed light. Entanglement is obtained in steady state, and can be increased by manipulating the atoms locally. We study the effects of imperfections, and show how to scale up the scheme to build a quantum network.

Daniel C. Cole, Yi Zou

The behavior of a classical charged point particle under the influence of only a Coulombic binding potential and classical electromagnetic zero-point radiation, is shown to yield agreement with the probability density distribution of Schroedinger&#39;s wave equation for the ground state of hydrogen. These results, obtained without any fitting parameters, aga

O. Beck, D. Heinemann, D. Kolb

We present a multigrid scheme for the solution of finite-element Hartree-Fock equations for diatomic molecules. It is shown to be fast and accurate, the time effort depending linearly on the number of variables. Results are given for the molecules LiH, BH, N_2 and for the Be atom in our molecular grid which agrees very well with accurate values from an atomi

Alexei A. Koulakov, Dmitry N. Tsigankov

We present a theoretical model for retinocollicular map development, which can account for intriguing behaviors observed in gain-of-function experiments in knock-in mice by Brown et al., including bifurcation in heterozygous Isl2/EphA3 knock-ins. The model is based on known chemical labels, axonal repulsion/competition, stochasticity and uses Markov chain de

D. Jaramillo, N. Vanegas

We present a pedagogical approach to the Lorentz group. We start by introducing a compact notation to express the elements of the fundamental representation of the rotations group.Lorentz coordinate transformations are derived in a novel and compact form. We show how to make a Lorentz transformation on the electromagnetic fields as well. A covariant time-der

G. N. Throumoulopoulos, K. Hizanidis, H. Tasso

In the above entitled recent publication by Giovanni Lapenta [Phys. Rev. Lett. Vol 90, 135005 (2003) ] it is claimed construction of a new class of solitonlike solutions for the Grad-Shafranov equation in plane geometry. It is proved here that, because of the mathematically erroneous choice \nabla p= |Ψ|^2 Ψ\nabla Ψfor an analytic continuation of the poloida