April 2003 arXiv papers — page 6

S. I. Dorozhkin

For high-mobility two-dimensional electrons at a GaAs/AlGaAs heterojunction, we have studied, both experimentally and theoretically, the recently discovered giant magnetoresistance oscillations with nearly zero resistance in the oscillation minima which appear under microwave radiation. We have proposed a model based on nonequilibrium occupation of Landau le

A. V. Bobyl, D. V. Shantsev, Y. M. Galperin, A. A. F. Olsen

We report on the first spatially resolved observation of mesoscopic flux jumps in superconducting films. Magneto-optical imaging was used to visualize the flux penetration in MgB2 films subjected to a slowly varying perpendicular field. Below 10 K, flux jumps with typical size 10-20 microns and regular shape are found to occur at random locations along the f

S. Rayaprol, Krushna Mavani, C. M. Thaker, D. S. Rana

Mo-substituted triple perovskite superconducting samples with the stoichiometric composition La(1.5)Nd(0.5)Ca(1)Ba(2)[Cu(1-x)Mo(x)](5)O(z), [LNCBCuMO] with x = 0.00, 0.01, 0.03, 0.05 and 0.10, have been investigated using X-ray diffraction, electrical resistivity, magnetic susceptibility, magnetization and oxygen content measurements. The observed reduction

T. R. Krishna Mohan, Surajit Sen

Impulses efficiently propagate into nominally dry granular beds and backscatter from buried inclusions in such beds may be potentially exploited to image shallow buried objects (SBOs). However, reliable imaging of SBOs requires ``cleaning up'' of surface vibrations, and, in addition to 3D particle dynamics simulations, a phenomenological model to par

M. Tierz

We address the construction of stable random matrix ensembles as the generalization of the stable random variables (Levy distributions). With a simple method we derive the Cauchy case, which is known to have remarkable properties. These properties allow for such an intuitive method -that relies on taking traces- to hold. Approximate but general results regar

Paul L. Schechter

Simple models for lensing potentials that successfully reproduce the positions of quadruple images to high accuracy fail abysmally in reproducing the flux ratios of the multiple images, suggesting the presence of small scale structure within the lensing galaxies. It has been argued that the flux ratio anomalies observed at radio wavelengths signal the presen

J. Greiner, M. Orio, N. Schartel

We report on three X-ray observations of Nova LMC 2000 with XMM at 17, 51 and 294 days after the maximum, respectively. X-ray spectral fits show a concordant decrease of the absorbing column and the X-ray luminosity. No supersoft X-ray emission is detected. The mass of the ejected shell is determined to be (less than) 7.5*E-5 msun. Though data are sparse, on

Martin Sahlen

Using the MacGibbon-Webber model, the instantaneous photon (gamma-ray) emission spectra from PBHs in the Standard Model and mSUGRA benchmark models were investigated numerically. The point source and diffuse gamma-ray spectra from PBHs were also found numerically. It was found that the instantaneous photon flux from PBHs in mSUGRA benchmark models is general

S. Mereghetti, D. Gotz, A. Tiengo, V. Beckmann

We present INTEGRAL and XMM-Newton observations of the prompt gamma-ray emission and the X-ray afterglow of GRB030227, the first GRB for which the quick localization obtained with the INTEGRAL Burst Alert System (IBAS) has led to the discovery of X-ray and optical afterglows. GRB030227 had a duration of about 20 s and a peak flux of 1.1 photons cm^-2 s^-1 in

K. M. Pontoppidan, E. Dartois, E. F. van Dishoeck, W. -F. Thi

We present detections of the absorption band at 3.53 micron due to solid methanol toward three low-mass young stellar objects located in the Serpens and Chameleon molecular cloud complexes. The sources were observed as part of a large spectroscopic survey of ~40 protostars. This is the first detection of solid methanol in the vicinity of low mass (M <1 Msol)

S. Moehler, W. B. Landsman, A. V. Sweigart, F. Grundahl

We present the results of spectroscopic analyses of hot horizontal branch (HB) stars in M 13 and M 3, which form a famous ``second parameter&#39;&#39; pair. From the spectra and Stroemgren photometry we derived -- for the first time in M 13 -- atmospheric parameters (effective temperature and surface gravity). For stars with Stroemgren temperatures between 1

Kaiki Taro Inoue, Masashi Chiba

A significant fraction of non-baryonic or baryonic dark matter in galactic halos may consist of MASsive Compact Objects (MASCOs) with mass M=10^{1-4}M_{sun}. Possible candidates for such compact objects include primordial black holes or remnants of primordial (Population III) stars. We propose a method for directly detecting MASCOs in extragalactic halos, us

Tsutomu T. Takeuchi, Hiroyuki Hirashita, Takako T. Ishii, Leslie K. Hunt

The small grain sizes produced by Type II supernova (SN II) models in young, metal-poor galaxies make the appearance of their infrared (IR) spectral energy distribution (SED) quite different from that of nearby, older galaxies. To study this effect, we have developed a model for the evolution of dust content and the IR SED of low-metallicity, extremely young

David C. Murphy, Philip C. Myers

Deep JHKs photometry was obtained towards eight dense molecular cores and J-H vs. H-Ks color-color plots are presented. Our photometry, sensitive to the detection of a 1 solar mass, 1 X 10^6 year old star through approx. 35 - 50 magnitudes of visual extinction, shows no indication of the presence of star/disk systems based on J-H vs. H-Ks colors of detected

Robert D. Ferdman, Harvey B. Richer, James Brewer, Greg G. Fahlman

Time-series data taken with the Hubble Space Telescope of a field six core radii (~5&#39;) from the center of the globular cluster Messier 4, and covering a period of about 10 weeks in early 2001, have been analyzed in search of variable objects. Various criteria were employed to select candidate variable stars. Period searches were performed on the selected

Yili Wang, David Atwood

We study the inclusive semileptonic rare decay $b \to s l^+ l^-$ in minimal supergravity model (mSUGRA). If tan$β$ is large, down-type quark mass matrices and their Yukawa couplings cannot be diagonalized at the same basis. This induces the flavor violating neutral Higgs boson couplings. These couplings contribute significantly to decay $b \to s mu^+ mu^-$ a

J. Alfaro, H. A. Morales-Técotl, M. Reyes, L. F. Urrutia

We provide a method and the results for the calculation of the holonomy of a Yang-Mills connection in an arbitrary triangular path, in an expansion (developed here to fifth order) in powers of the corresponding segments. The results might have applications in generalizing to Yang-Mills fields previous calculations of the corrections to particle dynamics indu

Shanti Deemyad, James S. Schilling

The dependence of the superconducting transition temperature T_{c} on nearly hydrostatic pressure has been determined to 67 GPa in an ac susceptibility measurement for a Li sample embedded in helium pressure medium. With increasing pressure, superconductivity appears at 5.47 K for 20.3 GPa, T_{c} rising rapidly to ~ 14 K at 30 GPa. The T_{c}(P)-dependence to

F. Heidrich-Meisner, A. Honecker, D. C. Cabra, W. Brenig

We report a detailed analysis of the Drude weights for both thermal and spin transport in one dimensional spin-1/2 systems by means of exact diagonalization and analytic approaches at finite temperatures. Transport properties are studied first for the integrable XXZ model and second for various non-integrable systems such as the dimerized chain, the frustrat

Laurent Baulieu

In a previous work, it was shown that the 8-dimensional topological quantum field theory for a metric and a Kalb-Ramond 2-form gauge field determines N = 1 D = 8 supergravity. It is shown here that, the combination of this TQFT with that of a 3-form determines N = 2 D = 8 supergravity, that is, an untruncated dimensional reduction of N = 1 D = 11 supergravit

Michal Fabinger, Eva Silverstein

We study the entropy of concrete de Sitter flux compactifications and deformations of them containing D-brane domain walls. We determine the relevant causal and thermodynamic properties of these &#34;D-Sitter&#34; deformations of de Sitter spacetimes. We find a string scale correspondence point at which the entropy localized on the D-branes (and measured by

Peter Olsson, S. Teitel

We carry out the first numerical simulations to directly confirm the existence of a kink-antikink unbinding transition, T_w, along Ising-like domain walls in the two dimensional fully frustrated XY model. We comment on the possible implications of kink-antikink unbinding for the bulk phase transitions of the model.

Almut Beige

This paper discusses ways to implement two-qubit gate operations for quantum computing with cold trapped ions within one step. The proposed scheme is widely robust against parameter fluctuations and its simplicity might help to increase the number of qubits in present experiments. Basic idea is to use the quantum Zeno effect originating from continuous measu

Marieke Postma, Anupam Mazumdar

We study preheating, i.e., non-perturbative resonant decay, of flat direction fields, concentrating on MSSM flat directions and the right handed sneutrino. The difference between inflaton preheating and flaton preheating, is that the potential is more constraint in the latter case. The effects of a complex driving field, quartic couplings in the potential, a

Silvina M. Gatica, M. Mercedes Calbi, Milton W. Cole, Darrell Velegol

The three body (triple dipole) interaction of Axilrod, Teller and Muto (ATM) contributes 5 to 10 % of the total energy of condensed phases of inert elements. It is shown in this paper for clusters and films that a much larger or smaller ATM contribution can arise for other geometries or other atomic species. The ratio R of the three body interaction energy t

F. E. Close, J. J. Dudek

We make the first calculation of the electroweak couplings of hybrid mesons to conventional mesons appropriate to photoproduction and to the decays of $B$ or $D$ mesons. $E1$ amplitudes are found to be large and may contribute in charge exchange $γp \to n H^+$ allowing production of (amongst others) the charged $1^{-+}$ exotic hybrid off $a_2$ exchange. Axia

B. Muzykantskii, N. d&#39;Ambrumenil, B. Braunecker

We report exact results for the Fermi Edge Singularity in the absorption spectrum of an out-of-equilibrium tunnel junction. We consider two metals with chemical potential difference V separated by a tunneling barrier containing a defect, which exists in one of two states. When it is in its excited state, tunneling through the otherwise impermeable barrier is

M. Lachieze-Rey

The usual spherical harmonics $Y_{\ell m}$ form a basis of the vector space ${\cal V} ^{\ell}$ (of dimension $2\ell+1$) of the eigenfunctions of the Laplacian on the sphere, with eigenvalue $λ_{\ell} = -\ell ~(\ell +1)$. Here we show the existence of a different basis $Φ^{\ell}_j$ for ${\cal V} ^{\ell}$, where $Φ^{\ell}_j(X) \equiv (X \cdot N_j)^{\ell}$, the

Shigeki Onoda, Masatoshi Imada

Mott transitions are studied in the two-dimensional Hubbard model by a non-perturbative theory of correlator projection that systematically includes spatial correlations into the dynamical mean-field approximation. Introducing a nonzero second-neighbor transfer, a first-order Mott transition appears at finite temperatures and ends at a critical point or curv

P. A. Horvathy, L. Martina, P. C. Stichel

When the interaction potential is suitably reordered, the Moyal field theory admits two types of Galilean symmetries, namely the conventional mass-parameter-centrally-extended one with commuting boosts, but also the two-fold centrally extended ``exotic&#39;&#39; Galilean symmetry, where the commutator of the boosts yields the noncommutative parameter. In the

C. P. Burgess, N. S. Dzhalilov, T. I. Rashba, V. B. Semikoz

We analyze helioseismic waves near the solar equator in the presence of magnetic fields deep within the solar radiative zone. We find that reasonable magnetic fields can significantly alter the shapes of the wave profiles for helioseismic g-modes. They can do so because the existence of density gradients allows g-modes to resonantly excite Alfven waves, caus

Anton S. Galaev

The holonomy algebra $\g$ of an indecomposable Lorentzian (n+2)-dimensional manifold $M$ is a weakly-irreducible subalgebra of the Lorentzian algebra $\so_{1,n+1}$. L. Berard Bergery and A. Ikemakhen divided weakly-irreducible not irreducible subalgebras into 4 types and associated with each such subalgebra $\g$ a subalgebra $\h\subset \so_n$ of the orthogon

J. Balog, P. Weisz

The 7--particle form factors of the fundamental spin field of the O(3) nonlinear $σ$--model are constructed. We calculate the corresponding contribution to the spin--spin correlation function, and compare with predictions from the spectral density scaling hypothesis. The resulting approximation to the spin--spin correlation function agrees well with that com

Akira Kitagawa, Katsuji Yamamoto

We examine various manipulations of photon number states which can be implemented by teleportation technique with number sum measurement. The preparations of the Einstein-Podolsky-Rosen resources as well as the number sum measurement resulting in projection to certain Bell state may be done conditionally with linear optical elements, i.e., beam splitters, ph

R. Samadi, A. Nordlund, R. F. Stein, M. J. Goupil

A 3D simulation of the upper part of the solar convective zone is used to obtain information on the frequency component, chi_k, of the correlation product of the turbulent velocity field. This component plays an important role in the stochastic excitation of acoustic oscillations. A time analysis of the solar simulation shows that a gaussian function does no

Hiroyuki Yamane

In this paper, using a quantum superalgebra associated with the universal central extension of sl(2,2)^{(1)}, we introduce new R-matrices having an extra parameter x. As x\to 0, they become those associated with the symmetric and anti-symmetric tensor products of the copies of the vector representation of U_q sl(2,2)^{(1)}.

Chiaki Hikage, Jens Schmalzing, Thomas Buchert, Yasushi Suto

We present a first morphometric investigation of a preliminary sample from the SDSS of 154287 galaxies with apparent magnitude 14.5<m_r<17.5 and redshift 0.001<z<0.4. We measure the Minkowski Functionals, which are a complete set of morphological descriptors. To account for the complicated wedge--like geometry of the present survey data, we construct isodens

Han-Kuei Fu, Xiao-Gang He, Yu-Kuo Hsiao

The observed branching ratios for $B\to K η&#39;$ decays are much larger than factorization predictions in the Standard Model (SM). Many proposals have been made to reconcile the data and theoretical predictions. In this paper we study these decays within the SM using flavor U(3) symmetry. If small annihilation amplitudes are neglected, one needs 11 hadronic

Peter Kammel

We survey a new generation of precision muon lifetime experiments. The goal of the MuCap experiment is a determination of the rate for muon capture on the free proton to 1 percent, from which the induced pseudoscalar form factor $g_P$ of the nucleon can be derived with 7 percent precision. A measurement of the related $μ$d capture process with similar precis

Nicolas Moeller, Martin Schnabl

We study a simple model of p-adic closed and open strings. It sheds some light on the dynamics of tachyon condensation for both types of strings. We calculate the effect of static and decaying D-brane configurations on the closed string background. For closed string tachyons we find lumps analogous to D-branes. By studying their fluctuation spectrum and the

Ronald Fintushel, Ronald J Stern

We define an simple invariant of an embedded nullhomologous Lagrangian torus and use this invariant to show that many symplectic 4-manifolds have infinitely many pairwise symplectically inequivalent nullhomologous Lagrangian tori. We further show that for a large class of examples that lambda(T) is actually a C-infinity invariant. In addition, this invariant

Tatsuo Kobayashi, Oleg Lebedev

In the framework of $Z_N$ orbifolds, we discuss effects of heterotic string backgrounds including discrete Wilson lines on the Yukawa matrices and their connection to CP violation.

H. -D. Doebner, R. Zhdanov

Nonlinear Dirac equations (NLDE) are derived through a group N^2 of nonlinear (gauge) transformation acting in the corresponding state space. The construction generalises a construction for nonlinear Schrödinger equations. To relate N^2 with physically motivated principles we assume: locality (i.e. it contains no explicit derivative and no derivatives of the

J. Larson, S. Stenholm

In an earlier paper we have concluded that time-dependent parameters in atom-mode interaction can be utilized to modify the quantum field in a cavity. When an atom shoots through the cavity field, it is expected to experience a trigonometric time dependence of its coupling constant. We investigate the possibilities this offers to modify the field. As a point

B. Zeng, D. L. Zhou, Z. Xu, C. P. Sun

A protocol of quantum communication is proposed in terms of the multi-qubit quantum teleportation through cluster states (Phys. Rev. Lett. \textbf{86}, 910 (2001)). Extending the cluster state based quantum teleportation on the basic unit of three qubits (or qudits), the corresponding multi-qubit network is constructed for both the qubits and qudits (multi-l

Michael Clover

A local, time-retarded hidden variable model is described that fits the recently measured EPR data from the Innsbruck collaboration. The model is based on the idea that waves in the zero-point field convey information from the detectors to the source, stimulating the spontaneous emission of photons with definite polarizations. In order to match experimental

Qing-yu Cai

We show an improved ping-pong protocol which is based on the protocol showed by Kim Bostrom and Timo Felbinger [Phys. Rev. Lett. 89, 187902 (2002); quant-ph/0209040]. We show that our protocol is asymptotically secure key distribution and quasisecure direct communication using a single photon resource. And this protocol can be can be carried out with great e

I. Chajda, R. Halas

We involve a certain propositional logic based on ortholattices. We characterize the implicational reduct of such a logic and we show that its algebraic counterpart is the so-called orthosemilattice. Properties of congruences and congruence kernels of these algebras are described.

Benjamin Cowan

We discuss the potential for using microfabrication techniques for laser-driven accelerator construction. We introduce microfabrication processes in general, and then describe our investigation of a particular trial process. We conclude by considering the issues microfabrication raises for possible future structures.

Vitalie Eremeev, Ion Rasca, Florentin Paladi

A cluster theory based mathematical model was developed and used to simulate the dynamics of a system composed of a large number of interacting agents-clusters with different size. The case of a system formed by a constant total number of economic units (agents) in metastable (partial) equilibrium was considered, and the size effect on the formation of the g

Ulrich Mosel

Changes of hadronic properties in dense nuclear matter as predicted by theory have usually been investigated by means of relativistic heavy-ion reactions. In this talk I show that observable consequences of such changes can also be seen in more elementary reactions on nuclei. Particular emphasis is put on a discussion of photonuclear reactions; examples are

Boris Tomasik

I present fits with the so-called blast-wave model to single-particle spectra and HBT correlations from Au+Au collisions at a CMS energy of 130 AGeV. There is only little choice of freeze-out temperature and transverse flow velocity for which the model fits both the identified spectra and the correlation radii just well enough not to be excluded. The observe

R. Neubecker, B. Guetlich

We report the first experimental evidence of a successful synchronization of spatiotemporal chaos. The experiments were performed on two unidirectionally coupled, nonlinear-optical systems of single-feedback type. The synchronization was investigated for different degrees of complexity of the spontaneous structures. In all cases, the cross-correlation betwee

Yanguang Charles Li

In an early work, Bernoulli shift dynamics of submanifolds was established in a neighborhood of a homoclinic tube. In this article, we will present a concrete example: sine-Gordon equation under a quasi-periodic perturbation.

Yanguang Charles Li

Let $F$ be a $C^3$ diffeomorphism on a Banach space $B$. $F$ has a homoclinic tube asymptotic to an invariant manifold. Around the homoclinic tube, Bernoulli shift dynamics of submanifolds is established through shadowing lemma. This work removes an uncheckable condition of Silnikov [Equation (11), page 625 of L. P. Silnikov, Soviet Math. Dokl., vol.9, no.3,

Michael A. Ivanov

Two examples, not connected at present, from author&#39;s papers (Nuovo Cim., 1992, v.105A, p.77 [hep-th/0207210] and GRG, 1999, v.31, p.1431 [gr-qc/0207017]) are considered here in which a physical model has discrete symmetries and additional non-observable coordinates or parameters. Then it is possible to introduce some apparent continuous symmetries of th

Alexander Fedotov, Frederic Klopp

In this paper, we study spectral properties of a family of quasi-periodic Schrodinger operators on the real line in the adiabatic limit. We assume that the adiabatic iso-energetic curves are extended along the momentum direction. In the energy intervals where this happens, we obtain an asymptotic formula for the Lyapunov exponent, and show that the spectrum

Edward A. Bender, E. Rodney Canfield, L. Bruce Richmond, Herbert S. Wilf

The quantity $f(n,r)$, defined as the number of permutations of the set $[n]=\{1,2,... n\}$ whose fixed points sum to $r$, shows a sharp discontinuity in the neighborhood of $r=n$. We explain this discontinuity and study the possible existence of other discontinuities in $f(n,r)$ for permutations. We generalize our results to other families of structures tha

Arnold W. Miller

In this paper we prove that if there is a Borel-cover gamma-set of cardinality the continuum, then there is one which is not hereditary. A set of reals X is a Borel-cover gamma-set iff for every countable family of Borel sets which is an omega-cover contains a gamma-cover. This is also denoted S_1(Borel_omega, Borel_gamma). This result partially answers a qu

Edith Adan-Bante

Let G be a finite solvable group and $χ\in \Irr(G)$ be a faithful character. We show that the derived length of G is bounded by a linear function of the number of distinct irreducible constituents of $χ\barχ$. We also discuss other properties of the decomposition of $χ\barχ$ into its irreducible constituents.

A. Muhammed Uludag

Some ball-quotient orbifolds are related by covering maps. We exploit these coverings to find infinite towers of orbifolds uniformized by the complex 2-ball and some orbifolds over K3 surfaces uniformized by the 2-ball. Corresponding lattices are all arithmetic and commensurable. We also give, along with infinitely many reducible examples, an infinite series

Nevin Kapur

Search trees are fundamental data structures in computer science. We study functionals on random search trees that satisfy recurrence relations of a simple additive form. Many important functionals including the space requirement, internal path length, and the so-called shape functional fall under this framework. Our goal is to derive asymptotics of moments

William P. Orrick, Bruce Solomon, Roland Dowdeswell, Warren D. Smith

We report new world records for the maximal determinant of an n-by-n matrix with entries +/-1. Using various techniques, we beat existing records for n=22, 23, 27, 29, 31, 33, 34, 35, 39, 45, 47, 53, 63, 69, 73, 77, 79, 93, and 95, and we present the record-breaking matrices here. We conjecture that our n=22 value attains the globally maximizing determinant

K. Zainoulline

We prove the version of Knebusch&#39;s Norm principle for simple extensions of (semi-)local rings. As an application we prove the Grothedieck-Serre&#39;s conjecture on principal homogeneous spaces for the split case of the spinor group.

Roland Queme

This paper is a contribution to the description of some congruences on the odd prime factors of the class number of the number fields. An example of results obtained is: Let L/Q be a finite Galois solvable extension with [L:Q]=N, where N > 1 is odd. Let h(L) be the class number of L. Suppose that h(L) > 1. Let p be a prime dividing h(L). Let r be the rank of

Tomasz Kapela, Piotr Zgliczynski

We consider a question of finding a periodic solution for the planar Newtonian N-body problem with equal masses, where each body is travelling along the same closed path. We provide a computer assisted proof for the following facts: local uniqueness and convexity of Chenciner and Montgomery Eight, an existence (and local uniqueness) for Gerver&#39;s SuperEig

Aaron Bertram, Ionut Ciocan-Fontanine, Bumsig Kim

We give two proofs of a conjecture of Hori and Vafa which expresses the J-function (i.e, the generating function for 1-point descendant Gromov-Witten invariants) of a Grassmannian in terms of the J-function of a product of projective spaces. Similar relations are obtained for two-point descendants, and three-point (primary) Gromov-Witten invariants. As an ap

Edith Adan-Bante

Let p be a prime number. Let G be a finite p-group and $χ\in Irr(G)$. Denote by $\barχ \in Irr(G)$ the complex conjugate of $χ$. Assume that $χ(1)=p^n$. We show that the number of distinct irreducible constituents of the product $χ\barχ$ is at least $2n(p-1)+1$.

Dan Abramovich, Jiun C. Chen

Given a birational modification $X \to Y$ of complex projective varieties with fiber dimension 1 and rational singularities, consider the main component of Bridgeland&#39;s moduli space $W \to Y$ of perverse point sheaves on $X/Y$. We give criteria for the normalization of $W$ to coincide with the transform (flip/flop) $X^+ \to Y$ of $X \to Y$. First, this h

Yoonweon Lee

In this paper we first establish the relation between the zeta-determinant of a Dirac Laplacian with the Dirichlet boundary condition and the APS boundary condition on a cylinder. Using this result and the gluing formula of the zeta-determinant given by Burghelea, Friedlander and Kappeler with some assumptions, we prove the adiabatic decomposition theorem of

Baris Coskunuzer

We construct a pair of transverse genuine laminations on an atoroidal 3-manifold admitting transversely orientable uniform 1-cochain. The laminations are induced by the uniform 1-cochain and they are indeed the &#34;straightening&#34; of the coarse laminations defined in [Ca], by using minimal surface techniques. Moreover, when you collapse these laminations

Roberto Percacci, Daniele Perini

Nonperturbative treatments of the UV limit of pure gravity suggest that it admits a stable fixed point with positive Newton&#39;s constant and cosmological constant. We prove that this result is stable under the addition of a scalar field with a generic potential and nonminimal couplings to the scalar curvature. There is a fixed point where the mass and all

Inyong Cho, Alexander Vilenkin

Numerical solutions of Einstein&#39;s and scalar-field equations are found for a global defect in a higher-dimensional spacetime. The defect has a $(3+1)$-dimensional core and a ``hedgehog&#39;&#39; scalar-field configuration in $n=3$ extra dimensions. For sufficiently low symmetry-breaking scales $η$, the solutions are characterized by a flat worldsheet geo

S. T. Love

Field theoretic models possessing a global internal fermionic shift symmetry are considered. When such a symmetry is realized locally, spin 3/2 fields appear naturally as gauge fields. Implementation of the gauging procedure requires not only the usual replacement of ordinary derivatives by covariant derivatives containing the spin 3/2 fields, but also the i

R. G. Leigh, A. C. Petkou

We argue that the N=1 higher-spin theory on AdS4 is holographically dual to the N=1 supersymmetric critical O(N) vector model in three dimensions. This appears to be a special form of the AdS/CFT correspondence in which both regular and irregular bulk modes have similar roles and their interplay leads simultaneously to both the free and the interacting phase

Antonio Campos

Brane gas cosmology is a scenario inspired by string theory which proposes a simple resolution to the initial singularity problem and gives a dynamical explanation for the number of spatial dimensions of our universe. In this work we have studied analytically and numerically the late-time behaviour of these type of cosmologies taking a proper care of the ann

A. Hiorth, J. O. Eeg

We present a calculation of the β-term for D^* --> D gamma within a heavy-light chiral quark model. Within the model, soft gluon effects in terms of the gluon condensate with lowest dimension are included. Also, calculations of 1/m_c corrections are performed. We find that the value of βis rather sensitive to the constituent quark mass compared to other quan

Marco Battaglia, Stefania De Curtis, Albert De Roeck, Daniele Dominici

Models with 3-branes in extra dimensions typically imply the existence of a radion, phi that can mix with the Higgs, h, thereby modifying the Higgs properties and the prospects for its detectability at the LHC. The presence of the phi will extend the scope of the LHC searches. Detection of both the phi and the h might be possible. In this paper, we study the

W. Bernreuther, A. Brandenburg, Z. G. Si, P. Uwer

We discuss the spin properties of top quark pairs produced at hadron colliders at next-to-leading order in the coupling constant alpha_s of the strong interaction. Specifically we present, for some decay channels, results for differential angular distributions that are sensitive to t tbar spin correlations.

S. Digal, S. Fortunato, P. Petreczky

We study the properties of the free energy of infinitely heavy quark anti-quark pair in SU(2) gauge theory. By means of lattice Monte Carlo simulations we calculated the free energies in the singlet, triplet and color averaged channels, both in the confinement and in the deconfinement phase. The singlet and triplet free energies are defined in Coulomb gauge

Wolfram Schroers

This thesis is focused on the implementation and the application of a novel kind of algorithm which is expected to overcome the limitations of older schemes. This new algorithm is named Multiboson Method. It allows to simulate an arbitrary number of dynamical fermion flavors, which can in principle have different masses. It will be shown that it exhibits bet

Ron Wiltshire

Spherically symmetric static fluid sources are endowed with rotation and embedded in Kerr empty space-time up to an including quadratic terms in an angular velocity parameter using Darmois junction conditions. Einstein&#39;s equation&#39;s for the system are developed in terms of linear ordinary differential equations. The boundary of the rotating source is

Erkan Tuzel, Martin Strauss, Thomas Ihle, Daniel M. Kroll

Explicit expressions for the transport coefficients of a recently introduced stochastic model for simulating fluctuating fluid dynamics are derived in three dimensions by means of Green-Kubo relations and simple kinetic arguments. The results are shown to be in excellent agreement with simulation data. Two collision rules are considered and their computation

Ping Zhang, Qi-Kun Xue, X. C. Xie

Non-equilibrium spin transport through an interacting quantum dot is analyzed. The coherent spin oscillations in the dot provide a generating source for spin current. In the interacting regime, the Kondo effect is influenced in a significant way by the presence of the precessing magnetic field. In particular, when the precession frequency is tuned to resonan

Emmanuel Tannenbaum, Eric Deeds, Eugene I. Shakhnovich

This paper develops an analytically tractable model for determining the equilibrium distribution of mismatch repair deficient strains in unicellular populations. The approach is based on the single fitness peak (SFP) model, which has been used in Eigen&#39;s quasispecies equations in order to understand various aspects of evolutionary dynamics. As with the q

B. Eiermann, P. Treutlein, Th. Anker, M. Albiez

We demonstrate the control of the dispersion of matter wave packets utilizing periodic potentials. This is analogous to the technique of dispersion management known in photon optics. Matter wave packets are realized by Bose-Einstein condensates of 87Rb in an optical dipole potential acting as a one-dimensional waveguide. A weak optical lattice is used to con

A. G. Lebed, M. J. Naughton

We suggest an analytical theory to describe angular magnetic oscillations recently discovered in quasi-one-dimensional conductor (TMTSF)2PF6 [see Phys. Rev. B, 57, 7423 (1998)] and define the positions of the oscillation minima. The origin of these oscillations is related to interference effects resulting from an interplay of quasi-periodic and periodic (&#3

Tomas Lofwander, Mikael Fogelstrom, J. A. Sauls

We present theoretical calculations and predictions for the shot noise in voltage biased junctions of $d_{x^2-y^2}$ superconductors and normal metal counter-electrodes. In the clean limit for the d-wave superconductor the shot noise vanishes at zero voltage because of resonant Andreev reflection by zero-energy surface bound states. We examine the sensitivity

Satoru Nakatsuji, David Pines, Zachary Fisk

We present a phenomenological solution of the Kondo lattice that is derived from an analysis of the bulk specific heat and spin susceptibility of the heavy electron superconductor CeCoIn5. We find that below a crossover temperature corresponding to the intersite coupling scale, T* ~ 45 K, the Kondo gas (of non-interacting Kondo impurities) partially condense

A. P. Finne, T. Araki, R. Blaauwgeers, V. B. Eltsov

Hydrodynamic flow in both classical and quantum fluids can be either laminar or turbulent. To describe the latter, vortices in turbulent flow are modelled with stable vortex filaments. While this is an idealization in classical fluids, vortices are real topologically stable quantized objects in superfluids. Thus superfluid turbulence is thought to hold the k

Nestor E. Massa, Helio C. N. Tolentino, Horacio Salva, Jose Antonio Alonso

We combine infrared reflectivity and EXAFS (Extended X-ray Absorption Fine Structure) techniques to study the solid solution La0.67Ca0.33MnO3 prepared by different methods yielding samples with different insulator-metal transition temperatures (TIM). While the small polaron analysis of the optical conductivity provides a natural description for the higher fr

I. A. Sergienko, S. H. Curnoe

We describe the low temperature behaviour of the magnetic susceptibility of Cd2Re2O7 in terms of a Landau theory of structural phase transitions. We calculate the zero temperature Pauli susceptibility using a tight-binding approach to reveal the mechanism of coupling between the structural order parameter and itinerant magnetism.

Ingmar Glauche, Wolfram Krause, Rudolf Sollacher, Martin Greiner

Wireless multi-hop ad hoc communication networks represent an infrastructure-less and self-organized generalization of todays wireless cellular networks. Connectivity within such a network is an important issue. Continuum percolation and technology-driven mutations thereof allow to address this issue in the static limit and to construct a simple distributed

A. A. Taskin, A. N. Lavrov, Yoichi Ando

In RBaCo_{2}O_{5+x} compounds (R is rare earth), a ferromagnetic-antiferromagnetic competition is accompanied by a giant magnetoresistance. We study the magnetization of detwinned GdBaCo_{2}O_{5.5} single crystals, and find a remarkable uniaxial anisotropy of Co^{3+} spins which is tightly linked with the chain oxygen ordering in GdO_{0.5} planes. Reflecting

L. Frappat, A. Sciarrino, P. Sorba

The distribution functions of the codon usage probabilities, computed over all the available GenBank data, for 40 eukaryotic biological species and 5 chloroplasts, do not follow a Zipf law, but are best fitted by the sum of a constant, an exponential and a linear function in the rank of usage. For mitochondriae the analysis is not conclusive. A quantum-mecha

Ludovic Berthier, A. P. Young

We study numerically the properties of local low-energy excitations in the two-dimensional Ising spin glass. Given the ground state, we determine the lowest-lying connected cluster of flipped spins containing one given spin, either with a fixed volume, or with a volume constrained to lie in a certain range. Our aim is to understand corrections to the scaling

Yu. S. Dedkov, M. Poygin, D. Vyalikh, A. Starodubov

Angle-resolved photoemission spectroscopy and Auger electron spectroscopy have been applied to study the intercalation process of silver underneath a monolayer of graphite (MG) on Ni(111). The room-temperature deposition of silver on top of MG/Ni(111) system leads to the islands-like growth of Ag on top of the MG. Annealing of the &#34;as-deposited&#34; syst

S. G. Sharapov, V. P. Gusynin, H. Beck

We present a study of the electrical and thermal conductivities of the $d$-density wave (DDW) state in an external magnetic field $B$ in the low temperature regime and in the presence of impurities. We show that in the zero temperature limit, $T \to 0$, the Wiedemann-Franz (WF) law remains intact. For finite $T$ the WF law violation is possible and it is enh

Mukunda P. Das, Frederick Green

We review the conceptual structure of the Landauer theory of electron transport in the light of quantum kinetics, the orthodox framework for describing conductance at all scales. In a straightforward analysis, we assess popular claims for a rational link between Landauer theory on the one hand, and orthodox microscopics on the other. The need to explicitly i

A. V. Syromyatnikov, S. V. Maleyev

We study the nature of the double-peak specific heat structure in kagome clusters. That containing 12 spins is considered thoroughly by numerical diagonalization. Simple models are proposed revealing the low-$T$ peak nature at $T_l<Δ$ ($Δ$ is the spin gap) in this case and in those of larger clusters studied so far. We show that the rapid increase in density