November 2007 arXiv papers — page 44

P. Q. Hung

The Lepton Flavour Violating (LFV) processes $μ\to e γ$ and $τ\to μγ$ are estimated in a model of electroweak-scale right-handed neutrinos. The present bounds on the branching ratios, $B(μ\to e γ)< 1.2 \times 10^{-11}$, $B(τ\to μγ) < 6.8 \times 10^{-8}$ (BaBar) and $< 4.5 \times 10^{-8}$ (Belle), puts strong constraints on the parameters of the model. This c

Ching-Ming Chen, Tianjun Li, V. E. Mayes, D. V. Nanopoulos

We study the possible phenomenology of a three-family Pati-Salam model constructed from intersecting D6-branes in Type IIA string theory on the T^6/(Z2 x Z2) orientifold with some desirable semi-realistic features. In the model, tree-level gauge coupling unification is achieved automatically at the string scale, and the gauge symmetry may be broken to the St

H. Lu, M. J. Perry, C. N. Pope

It has long been appreciated that the toroidal reduction of any gravity or supergravity to two dimensions gives rise to a scalar coset theory exhibiting an infinite-dimensional global symmetry. This symmetry is an extension of the finite-dimensional symmetry G in three dimensions, after performing a further circle reduction. There has not been universal agre

George M. Bergman

If C and D are varieties of algebras in the sense of general algebra, then by a representable functor C --> D we understand a functor which, when composed with the forgetful functor D --> Set, gives a representable functor in the classical sense; Freyd showed that these functors are determined by D-coalgebra objects of C. Let Rep(C,D) denote the category of

Yossi Farjoun, John C. Neu

A classic problem, the design of the tallest column, is solved again using a different method. By the use of a similarity solution the equations are transformed and the difficult singularity at the endpoint is peeled away. The resulting autonomous system has a critical point and the solution must be on its stable manifold. The solution is found by starting n

Massimiliano Zanin

The existence of forbidden patterns, i.e., certain missing sequences in a given time series, is a recently proposed instrument of potential application in the study of time series. Forbidden patterns are related to the permutation entropy, which has the basic properties of classic chaos indicators, thus allowing to separate deterministic (usually chaotic) fr

Benjamin J. Wilson

One may construct, for any function on the integers, an irreducible module of level zero for affine sl(2), using the values of the function as structure constants. The modules constructed using exponential-polynomial functions realise the irreducible modules with finite-dimensional weight spaces in the category Õ of Chari. In this work, an expression for the

Linqing Wen, Xilong Fan, Yanbei Chen

We report for the first time a method-independent geometrical expression for the angular resolution of an arbitrary network of interferometric gravitational wave (GW) detectors when the arrival-time of a GW is unknown. We discuss the implications of our results on how to improve angular resolutions of a GW network and on improvements of localization methods.

R. A. Scheepmaker, H. J. G. L. M. Lamers, S. S. Larsen, P. Anders

Aims: We study a peculiar object with a projected position close to the nucleus of M51. It is unusually large for a star cluster in M51 and we therefore investigate the three most likely options to explain this object: (a) a background galaxy, (b) a cluster in the disk of M51 and (c) a cluster in M51, but in front of the disk. Methods: We use HST/ACS and HST

Dennis Koh

In this paper we prove the existence of long time solutions for the parabolic equation for closed magnetic geodesics.

Anastasia Doikou

The open critical XXZ spin chain with a general right boundary and a trivial diagonal left boundary is considered. Within this framework we propose a simple computation of the exact generic boundary S-matrix (with diagonal and non-diagonal entries), starting from the `bare&#39; Bethe ansatz equations. Our results coincide with the ones obtained by Ghoshal an

Brian Conrey, David W. Farmer, Martin R. Zirnbauer

We give a new heuristic for all of the main terms in the quotient of products of L-functions averaged over a family. These conjectures generalize the recent conjectures for mean values of L-functions. Comparison is made to the analogous quantities for the characteristic polynomials of matrices averaged over a classical compact group.

Sanghyuk Lee

We study pointwise convergence of the solutions to Schrödinger equations with initial datum $f\in H^s(\mathbb R^n)$. The conjecture is that the solution $e^{itΔ}f$ converges to $f$ almost everywhere for all $f\in H^s(\mathbb R^n)$ if and only if $s\ge 1/4$. The conjecture is known true for one spatial dimension and the convergence when $s>1/2$ was verified f

Riccardo Ricci, Arkady A. Tseytlin, Martin Wolf

We discuss an interplay between T-duality and integrability for certain classical non-linear sigma models. In particular, we consider strings on the AdS_5 x S^5 background and perform T-duality along the four isometry directions of AdS_5 in the Poincare patch. The T-dual of the AdS_5 sigma model is again a sigma model on an AdS_5 space. This classical T-dual

Swarnendu Tripathi, John J. Portman

The key to understanding a protein&#39;s function often lies in its conformational dynamics. We develop a coarse-grained variational model to investigate the interplay between structural transitions, conformational flexibility and function of N-terminal calmodulin (nCaM) domain. In this model, two energy basins corresponding to the ``closed&#39;&#39; apo con

C. Karrasch, A. Oguri, V. Meden

We investigate the Josephson current J(ϕ) through a quantum dot embedded between two superconductors showing a phase difference ϕ. The system is modeled as a single Anderson impurity coupled to BCS leads, and the functional and the numerical renormalization group frameworks are employed to treat the local Coulomb interaction U. We reestablish the picture of

Gordon A. H. Walker

The Microvariability and Oscillations of STars (MOST) photometric satellite has already undertaken more than 64 primary campaigns which include some clusters and has obtained observations of >850 secondary stars of which ~180 are variable. More than half of the variables pulsate, with the majority being of B-type. Since 2006 January, MOST has operated with o

Danilo Silva, Frank R. Kschischang, Ralf Kötter

The problem of error control in random linear network coding is addressed from a matrix perspective that is closely related to the subspace perspective of K\"otter and Kschischang. A large class of constant-dimension subspace codes is investigated. It is shown that codes in this class can be easily constructed from rank-metric codes, while preserving their d

Andreas S. Kronfeld

Many results from lattice QCD of broad importance to particle and nuclear physics are obtained with 2+1 flavors of staggered sea quarks. In the continuum limit, staggered fermions yield four species, called tastes. To reduce the number of tastes to one (per flavor), the simulation employs the fourth root of the four-taste staggered fermion determinant. This

Claude Bernard, Maarten Golterman, Yigal Shamir, Stephen Sharpe

We discuss the properties of &#39;t Hooft vertices in partially quenched and rooted versions of QCD in the continuum. These theories have a physical subspace, equivalent to ordinary QCD, that is contained within a larger space that includes many unphysical correlation functions. We find that the &#39;t Hooft vertices in the physical subspace have the expecte

M. Bellazzini, S. Perina, S. Galleti, L. Federici

In the log Age vs. integrated absolute magnitude (M_V) plane, the open clusters of the Milky Way form a well-defined band parallel to theoretical sequences decribing the passive evolution of Simple Stellar Populations and display a pretty sharp upper threshold in mass (M ~ 2X 10^4 M_{sun}) over a 4 dex range of ages.

Bruno Chiarellotto, Andrea Pulita

We consider a complete discrete valuation field of characteristic p, with possibly non perfect residue field. Let V be a rank one continuous representation with finite local monodromy of its absolute Galois group. We will prove that the Arithmetic Swan conductor of V (defined after Kato in [Kat89] which fits in the more general theory of [AS02] and [AS06]) c

Amand Faessler, Thomas Gutsche, Valery E. Lyubovitskij, Chalump Oonariya

We discuss the sensitivity of nucleon properties (mass, magnetic moments and electromagnetic form factors) on the variation of the pseudoscalar meson masses in the context of the perturbative chiral quark model. The obtained results are compared to data and other theoretical predictions.

J. Barranco, O. G. Miranda, C. A. Moura, J. W. F. Valle

We present a detailed analysis on nonstandard neutrino interactions (NSI) with electrons including all muon and electron (anti)-neutrino data from existing accelerators and reactors, in conjunction with the ``neutrino counting&#39;&#39; data (e- e+ -> nu nu gamma) from the four LEP collaborations. First we perform a one-parameter-at-a-time analysis, showing

Bruno Scherrer

We consider the discrete-time infinite-horizon optimal control problem formalized by Markov Decision Processes. We revisit the work of Bertsekas and Ioffe, that introduced $λ$ Policy Iteration, a family of algorithms parameterized by $λ$ that generalizes the standard algorithms Value Iteration and Policy Iteration, and has some deep connections with the Temp

Michael Morello

We present CDF results on the branching fractions and time-integrated direct CP asymmetries for B0 and B0s decay modes into pairs of charmless charged hadrons (pions or kaons). We report also the first observation of B0s->DsK mode and the measurement of its branching fraction.

Mark Hindmarsh, Huiquan Li

The dynamic process of unstable D-branes decaying into stable ones with one dimension lower can be described by a tachyon field with a Dirac-Born-Infeld effective action. In this paper we investigate the fluctuation modes of the tachyon field around a two-parameter family of static solutions representing an array of brane-antibrane pairs. Besides a pair of z

Michael Kordosky, David Petyt

We report the results of a search for muon-neutrino disappearance by the Main Injector Neutrino Oscillation Search. The experiment uses two detectors separated by 734 km to observe a beam of neutrinos created by the Neutrinos at the Main Injector facility at Fermi National Accelerator Laboratory. The data were collected in the first 282 days of beam operatio

Bradley A. Chase, Andrew J. Landahl, J. M. Geremia

We present an efficient approach to continuous-time quantum error correction that extends the low-dimensional quantum filtering methodology developed by van Handel and Mabuchi [quant-ph/0511221 (2005)] to include error recovery operations in the form of real-time quantum feedback. We expect this paradigm to be useful for systems in which error recovery opera

Saibal Ray, Maxim Khlopov, Utpal Mukhopadhyay, Partha Pratim Ghosh

Among various phenomenological $Λ$ models, a time-dependent model $\dot Λ\sim H^3$ is selected here to investigate the $Λ$-CDM cosmology. Using this model the expressions for the time-dependent equation of state parameter $ω$ and other physical parameters are derived. It is shown that in $H^3$ model accelerated expansion of the Universe takes place at negati

L. Lavoura, H. Kuhbock

We propose a model for the quark masses and mixings based on an A_4 family symmetry. Three scalar SU(2) doublets form a triplet of A_4. The three left-handed-quark SU(2) doublets are also united in a triplet of A_4. The right-handed quarks are singlets of A_4. The A_4-symmetric scalar potential leads to a vacuum in which two of the three scalar SU(2) doublet

Satya N. Majumdar, Oriol Bohigas, Arul Lakshminarayan

A recent conjecture regarding the average of the minimum eigenvalue of the reduced density matrix of a random complex state is proved. In fact, the full distribution of the minimum eigenvalue is derived exactly for both the cases of a random real and a random complex state. Our results are relevant to the entanglement properties of eigenvectors of the orthog

J. G. Rosa, John March-Russell

We study the mechanism of particle production in the world-volume of a probe anti D6-brane (or D6 with SUSY breaking) moving in the background created by a fixed stack of $D6$-branes. We show that this may occur in a regime of parametric resonance when the probe&#39;s motion is non-relativistic and it moves at large distances from the source branes in low ec

Kayll Lake

Recently, Rindler and Ishak have argued that the bending of light is, in principle, changed by the presence of a cosmological constant since one must consider not only the null geodesic equation, but also the process of measurement. I agree with the fact that both must be considered. Here, on the basis of the mathematically exact solution to the classical be

N. Read

The low-energy effective quantum field theory of the edge excitations of a fully-gapped bulk topological phase corresponding to a local interaction Hamiltonian must be local and unitary. Here it is shown that whenever all the edge excitations propagate in the same direction with the same velocity, it is a conformal field theory. In particular, this is the ca

Xin Zhang

We comment on a recent paper by L. Baum and P. H. Frampton [Phys. Rev. Lett. 98, 071301 (2007)] where it was argued that the entropy problem can be resolved in a peculiar cyclic universe model through a deflation mechanism (i.e., the universe is fragmented into many disconnected causal patches at the turnaround). We point out that in this cyclic model the Hu

George I. Bell

Triangular peg solitaire is a well-known one-person game or puzzle. When one peg captures many pegs consecutively, this is called a sweep. We investigate whether the game can end in a dramatic fashion, with one peg sweeping all remaining pegs off the board. For triangular boards of side 6 and 8 (with 21 and 36 holes, respectively) the geometrically longest s

Benedikt M. Potscher, Hannes Leeb

We study the distributions of the LASSO, SCAD, and thresholding estimators, in finite samples and in the large-sample limit. The asymptotic distributions are derived for both the case where the estimators are tuned to perform consistent model selection and for the case where the estimators are tuned to perform conservative model selection. Our findings compl

Joonwoo Bae, Jae-Weon Lee, Jaewan Kim, Won-Young Hwang

In this work we relate the well-known no-go theorem that two non-orthogonal (mixed) quantum states cannot be perfectly discriminated, to the general principle in physics, the no-signalling condition. In fact, we derive the minimum error in discrimination between two quantum states, using the no-signalling condition.

F. Giazotto, F. Taddei

Spin-polarized transport is investigated in normal metal-superconductor (NS) junctions as a function of interface transmissivity as well as temperature when the density of states of a superconductor is Zeeman-split in response to an exchange field (h_exc). Similarly to the &#34;absolute spin-valve effect&#34; predicted by D. Huertas-Hernando et al. [Phys. Re

B. Bakalov, N. M. Nikolov, K. -H. Rehren, I. Todorov

The concept of global conformal invariance (GCI) opens the way of applying algebraic techniques, developed in the context of 2-dimensional chiral conformal field theory, to a higher (even) dimensional space-time. In particular, a system of GCI scalar fields of conformal dimension two gives rise to a Lie algebra of harmonic bilocal fields, V_m(x,y), where the

Carlos Hoyos, Biagio Lucini, Asad Naqvi

We compute the one-loop effective potential for the Polyakov loop on $S^3 times S^1$ for an asymptotically free gauge theory of arbitrary group $G$ and a generic matter content. We apply this result to study the phase structures of $G_2$, SO(N) and $Sp(2N)$ gauge theories which turn out to be in qualitative agreement with the results of lattice calculations.

I. Bausmerth, A. Recati, S. Stringari

We study the effect of the rotation on a harmonically trapped Fermi gas at zero temperature under the assumption that vortices are not formed. We show that at unitarity the rotation produces a phase separation between a non rotating superfluid (S) core and a rigidly rotating normal (N) gas. The interface between the two phases is characterized by a density d

Ewa L. Lokas

NGC 5128 is a well-studied elliptical galaxy with an excellent kinematic data set for planetary nebulae which has been modelled up till now only by solving the Jeans equation for spherical systems. As a first approximation beyond spherical symmetry we model the galaxy as an axisymmetric system flattened by rotation with isotropic velocity distribution. We pr

Sergey Mozgovoy

Given a curve over a finite field, we compute the number of stable bundles of not necessarily coprime rank and degree over it. We apply this result to compute the virtual Poincare polynomials of the moduli spaces of stable bundles over a curve. A similar formula for the virtual Hodge polynomials and motives is conjectured.

Richard J. Mathar

The two-dimensional surface of a bi-axial ellipsoid is characterized by the lengths of its major and minor axes. Longitude and latitude span an angular coordinate system across. We consider the egg-shaped surface of constant altitude above (or below) the ellipsoid surface, and compute the geodetic lines - lines of minimum Euclidean length - within this surfa

Jean-Francois Babadjian, Elvira Zappale, Hamdi Zorgati

A $Γ$-convergence analysis is used to perform a 3D-2D dimension reduction of variational problems with linear growth. The adopted scaling gives rise to a nonlinear membrane model which, because of the presence of higher order external loadings inducing a bending moment, may depend on the average in the transverse direction of a Cosserat vector field, as well

Xing-Hao Ye, Qiang Lin

We found strong similarities between the gravitational lensing and the conventional optical lensing. The similarities imply a graded refractive index description of the light deflection in gravitational field. We got a general approach to this refractive index in a static spherically symmetric gravitational field and obtained its exterior and interior soluti

Yuji Koike, Werner Vogelsang, Feng Yuan

Recent studies have shown that two widely-used mechanisms for single-transverse-spin asymmetries based on either twist-three contributions or on transverse-momentum-dependent (Sivers) parton distributions become identical in a kinematical regime of overlap. This was demonstrated for the so-called soft-gluon-pole and hard-pole contributions to the asymmetry a

Miguel Angel Javaloyes, Paolo Piccione

We introduce the notion of spectral flow along a periodic semi-Riemannian geodesic, as a suitable substitute of the Morse index in the Riemannian case. We study the growth of the spectral flow along a closed geodesic under iteration, determining its asymptotic behavior.

Balint Toth, Balint Veto

Let B(t), X(t) and Y(t) be independent standard 1d Borwnian motions. Define X^+(t) and Y^-(t) as the trajectories of the processes X(t) and Y(t) pushed upwards and, respectively, downwards by B(t), according to Skorohod-reflection. In a recent paper, Jon Warren proves inter alia that Z(t):= X^+(t)-Y^-(t) is a three-dimensional Bessel-process. In this note, w

A. Arbuzov, D. Bardin, S. Bondarenko, P. Christova

Radiative corrections to the neutral current Drell--Yan-like processes are considered. Complete one-loop electroweak corrections are calculated within the SANC system. Theoretical uncertainties are discussed. Numerical results are presented for typical conditions of LHC experiments.

T. Birkandan

We present a Maple11+GRTensorII based symbolic calculator for instanton metrics using Newman-Penrose formalism. Gravitational instantons are exact solutions of Einstein&#39;s vacuum field equations with Euclidean signature. The Newman-Penrose formalism, which supplies a toolbox for studying the exact solutions of Einstein&#39;s field equations, was adopted t

Akito Futaki, Yuji Sano

We extend Nadel&#39;s results on some conditions for the multiplier ideal sheaves to satisfy which are described in terms of an obstruction defined by the first author. Applying our extension we can determine the multiplier ideal sheaves on toric del Pezzo surfaces which do not admit Kähler-Einstein metrics. We also show that one can define multiplier ideal

T. Birkandan, M. Hortacsu

Dirac equation written on the boundary of the Nutku helicoid space consists of a system of ordinary differential equations. We tried to analyze this system and we found that it has a higher singularity than those of the Heun&#39;s equations which give the solutions of the Dirac equation in the bulk. We also lose an independent integral of motion on the bound

Peter Filip

Correction terms generated in the correlator analysis due to multiplicity-dependent observable mean are investigated. A procedure for subtraction of such terms from calculated correlator estimates is suggested and the obtained results are discussed.

Karl Tordrup, Klaus Molmer

We propose to encode quantum information in rotational excitations in a molecular ensemble. Using a stripline cavity field for quantum state transfer between the molecular ensemble and a Cooper pair box two-level system, our proposal offers a linear scaling of the number of qubits in our register with the number of rotationally excited states available in th

Isabel Goffa, Eric Jespers, Jan Okninski

Let A be a finitely generated commutative algebra over a field K with a presentation A=K < X_{1}, ..., X_{n} | R >, where R is a set of monomial relations in the generators X_{1}, ..., X_{n}. So A = K[S], the semigroup algebra of the monoid S=< X_{1}, ..., X_{n} | R >. We characterize, purely in terms of the defining relations, when A is an integrally closed

J. A. Rubino-Martin, J. Chluba, R. A. Sunyaev

The main goal of this work is to calculate the contributions to the cosmological recombination spectrum due to bound-bound transitions of helium. We show that due to the presence of helium in the early Universe unique features appear in the total cosmological recombination spectrum. These may provide a unique observational possibility to determine the relati

Toshifumi Itakura

This paper has been withdrawn by the author due to a crucial sign error in equation 1.

Mehmet Cenkci, Yilmaz Simsek, Mumun Can, Veli Kurt

The aim of this paper is to construct new Dedekind type sums. We construct generating functions of Barnes' type multiple Frobenius-Euler numbers and polynomials. By applying Mellin transformation to these functions, we define Barnes' type multiple l-functions, which interpolate Frobenius-Euler numbers at negative integers. By using generalizations of the Fro

S. -H. Park, Y. Y. Lee, Doyeol Ahn

Multi-valley effective mass theory for silicon quantum well structure is studied taking into account the external fields and the quantum interfaces. It is found that the phenomenological delta function potential, employed to explain the valley splitting caused by the quantum well interface in the previous work [Ref. 10], can be derived self-consistently from

Gennadiy Averkov, Gabriele Bianchi

The covariogram g_K of a convex body K in E^d is the function which associates to each x in E^d the volume of the intersection of K with K+x. In 1986 G. Matheron conjectured that for d=2 the covariogram g_K determines K within the class of all planar convex bodies, up to translations and reflections in a point. This problem is equivalent to some problems in

Anton Dzhamay

We establish the Lagrangian nature of the discrete isospectral and isomonodromic dynamical systems corresponding to the re-factorization transformations of the rational matrix functions on the Riemann sphere. Specifically, in the isospectral case we generalize the Moser-Veselov approach to integrability of discrete systems via the re-factorization of matrix

Weizhu Bao, Fong Yin Lim

In this paper, we propose an efficient and accurate numerical method for computing the ground state of spin-1 Bose-Einstein condensates (BEC) by using the normalized gradient flow or imaginary time method. The key idea is to find a third projection or normalization condition based on the relation between the chemical potentials so that the three projection p

A. Kappes

To complement the IceCube neutrino telescope currently under construction at the South Pole, the three Mediterranean neutrino telescope projects ANTARES, NEMO and NESTOR have joined forces to develop, construct and operate a km^3-scale neutrino telescope in the Mediterranean Sea. Since February 2006, the technical specifications and performance of such a det

Shoetsu Ogata

The article has been withdrawn by the author due to the existence of counterexamples.

Hironobu Sasaki

We study the inverse scattering problem for the three dimensional nonlinear Schroedinger equation with the Yukawa potential. The nonlinearity of the equation is nonlocal. We reconstruct the potential and the nonlinearity by the knowledge of the scattering states. Our result is applicable to reconstructing the nonlinearity of the semi-relativistic Hartree equ

Xiang Liu, Yan-Rui Liu, Wei-Zhen Deng, Shi-Lin Zhu

Since $Z^+(4430)$ lies very close to the threshold of $D^\ast{\bar D}_1$, we investigate whether $Z^+(4430)$ could be a loosely bound S-wave state of $D^\ast{\bar D}_1$ or $D^\ast{\bar D}^\prime_1$ with $J^P=0^-, 1^-, 2^-$, i.e., a molecular state arising from the one-pion-exchange potential. The potential from the crossed diagram is much larger than that fr

Takao Inoue, Robert W. Heath

A codebook based limited feedback strategy is a practical way to obtain partial channel state information at the transmitter in a precoded multiple-input multiple-output (MIMO) wireless system. Conventional codebook designs use Grassmannian packing, equiangular frames, vector quantization, or Fourier based constructions. While the capacity and error rate per

Maria Meiler, Ricardo Cordero-Soto, Sergei K. Suslov

We construct an explicit solution of the Cauchy initial value problem for the n-dimensional Schroedinger equation with certain time-dependent Hamiltonian operator of a modified oscillator. The dynamical SU(1,1) symmetry of the harmonic oscillator wave functions, Bargmann&#39;s functions for the discrete positive series of the irreducible representations of t

Vincenzo Cirigliano, Andrea De Simone, Gino Isidori, Isabella Masina

It has been recently shown that the quantum Boltzmann equations may be relevant for the leptogenesis scenario. In particular, they lead to a time-dependent CP asymmetry which depends upon the previous dynamics of the system. This memory effect in the CP asymmetry is particularly important in resonant leptogenesis where the asymmetry is generated by the decay

L. K. Morgan, M. A. Thompson, J. S. Urquhart, G. J. White

Context: Bright-rimmed clouds (BRCs) are potential examples of triggered star formation regions, in which photoionisation driven shocks caused by the expansion of HII regions induce protostellar collapse within the clouds. Aims: The main purpose of the paper is to establish the level of star formation occuring within a known set of BRCs. A secondary aim is t

Jiren Liu, Hongguang Bi, Li-Zhi Fang

Spectra of high redshift QSOs show deep Gunn-Peterson absorptions on the blue sides of the \Lya emissions lines. They can be decomposed into components called \Lya leaks, defined to be emissive regions in complementary to otherwise zero-fluxed absorption gaps. Just like \Lya absorption forests at low redshifts, \Lya leaks are both easy to find in observation

Zs. Kõvári, J. Bartus, M. Švanda, K. Vida

We demonstrate the power of the local correlation tracking technique on stellar data for the first time. We recover the spot migration pattern of the long-period RS CVn-type binary $σ$ Gem from a set of six Doppler images from 3.6 consecutive rotation cycles. The resulting surface flow map suggests a weak anti-solar differential rotation with $α\approx-0.002

Stefan Schumacher

Based on a microscopic many-particle theory we investigate the amplification of polaritons in planar semiconductor microcavities. We study a spatially perfectly isotropic microcavity system and excitation geometry. For this system, our analysis shows that a pump-induced vectorial polarization anisotropy can lead to a spatial anisotropy in the stimulated ampl

Ren Guo, Feng Luo

We study the rigidity of polyhedral surfaces using variational principle. The action functionals are derived from the cosine laws. The main focus of this paper is on the cosine law for a non-triangular region bounded by three possibly disjoint geodesics. Several of these cosine laws were first discovered and used by Fenchel and Nielsen. By studying the deriv

Mahir Bilen Can

In this paper we study the tangent spaces of the smooth nested Hilbert scheme $ Hil{n,n-1}$ of points in the plane, and give a general formula for computing the Euler characteristic of a $\TT^2$-equivariant locally free sheaf on $\Hil{n,n-1}$. Applying our result to a particular sheaf, we conjecture that the result is a polynomial in the variables $q$ and $t

Neil Bushong, Massimiliano Di Ventra

Recently, time-dependent current-density functional theory has been extended to include the dynamical interaction of quantum systems with external environments [Phys. Rev. Lett. {\bf 98}, 226403 (2007)]. Here we show that such a theory allows us to study a fundamentally important class of phenomena previously inaccessible by standard density-functional metho

Alexandra S. Landsman, Leah B. Shaw, Ira B. Schwartz

We consider a line of three mutually coupled lasers with time delays and study chaotic synchronization of the outer lasers. Two different systems are presented: optoelectronically coupled semiconductor lasers and optically coupled fiber lasers. While the dynamics of the two systems are very different, robust synchronization of end lasers is obtained in both

R. D. Alexander, P. J. Armitage, J. Cuadra, M. C. Begelman

We consider the effects of eccentricity on the fragmentation of gravitationally unstable accretion disks, using numerical hydrodynamics. We find that eccentricity does not affect the overall stability of the disk against fragmentation, but significantly alters the manner in which such fragments accrete gas. Variable tidal forces around an eccentric orbit slo

P. Winternitz, I. Yurdusen

The concept of superintegrability in quantum mechanics is extended to the case of a particle with spin s=1/2 interacting with one of spin s=0. Non-trivial superintegrable systems with 8- and 9-dimensional Lie algebras of first-order integrals of motion are constructed in two- and three-dimensional spaces, respectively.

V. Bozza, S. Calchi Novati, L. Mancini

We examine the possibility of observing gravitational lensing in the weak deflection regime by the supermassive black hole in the center of the galaxy M31. This black hole is significantly more massive than the black hole in the center of our Galaxy qualifying itself as a more effective lens. However, it is also more distant and the candidate stellar sources

Zs. Kővári, F. Vilardell, I. Ribas, K. Vida

We present $B$ and $V$ light curves of a large stellar flare obtained with the Wide Field Camera at the Isaac Newton 2.5-m telescope (La Palma). The source object is a faint ($m_V=21.38$) foreground star in the field of the Andromeda galaxy, with its most probable spectral type being dM4. We provide an estimate of the total flare energy in the optical range

Harvey B. Meyer

We derive non-perturbative sum rules in SU($N$) lattice gauge theory at finite temperature. They relate the susceptibilities of the trace anomaly and energy-momentum tensor to temperature derivatives of the thermodynamic potentials. Two of them have been derived previously in the continuum and one is new. In all cases, at finite latttice spacing there are im

Aharon Levy

The latest results on exclusive vector meson electroproduction from HERA are reviewed. In particular, the new high-statistics measurements of the rho^0 electroproduction are presented and compared to several models.

Liviu I. Nicolaescu

We investigate the poset of strata of a Schubert-like stratification of certain natural compactification of the space of hermitian $n\times n$ matrices. We prove that this poset is a modular ortholattice, we compute its Möbius function and we describe the topology of its order intervals.

Yossi Farjoun, John C. Neu

The problem of finding the optimal tapering of a free (non-supported) javelin is described and solved. For the optimal javelin, the lowest mode of vibration has the highest possible frequency. With this tapering inner damping will lead to the cessation of the vibration at the fastest possible rate. The javelin is modeled as a beam of uniform material. The di

N. B. Perkins, O. Sikora

We study magnetic excitations in vanadium spinel oxides AV$_2$O$_4$ (A=Zn, Mg, Cd) using two models: first one is a superexchange model for vanadium S=1 spins, second one includes in addition spin-orbit coupling, and crystal anisotropy. We show that the experimentally observed magnetic ordering can be obtained in both models, however the orbital ordering is

A. A. Pankov, N. Paver, A. V. Tsytrinov

Non-standard scenarios described by effective contactlike interactions can be revealed only by searching for deviations of the measured observables from the Standard Model (SM) predictions. If deviations were indeed observed within the experimental uncertainty, the identification of their source among the different non-standard interactions should be needed.

The DONuT Collaboration

The DONuT experiment collected data in 1997 and published first results in 2000 based on four observed $ν_τ$ charged-current (CC) interactions. The final analysis of the data collected in the experiment is presented in this paper, based on $3.6 \times 10^{17}$ protons on target using the 800 GeV Tevatron beam at Fermilab. The number of observed $ν_τ$ CC inte

Gerardo J. M. Luna, Jennifer L. Sokoloski, Koji Mukai

We present Suzaku X-ray observations of the recurrent nova T CrB in quiescence. T CrB is the first recurrent nova to be detected in the hard-X-ray band (E ~ 40.0 keV) during quiescence. The X-ray spectrum is consistent with cooling-flow emission emanating from an optically thin region in the boundary layer of an accretion disk around the white dwarf. The det

Antonina N. Fedorova, Michael G. Zeitlin

We present a family of methods, analytical and numerical, which can describe behaviour in (non) equilibrium ensembles, both classical and quantum, especially in the complex systems, where the standard approaches cannot be applied. We demonstrate the creation of nontrivial (meta) stable states (patterns), localized, chaotic, entangled or decoherent, from basi

Michele Sciacca, Maria Stella Mongiovì, David Jou

Two alternative Vinen&#39;s evolution equations for the vortex line density L in counterflow superfluid turbulence, are physically admissible and lead to analogous results in steady states. In Phys. Rev. B, 69, 094513 (2004) the most used of them was generalized to counterflow superfluid turbulence in rotating containers. Here, the analogous generalization f

Paolo Albini, Alessandro Toigo, Veronica Umanità

In quantum estimation theory and quantum tomography, the quantum state obtained by sampling converges to the `true&#39; unknown density matrix under topologies that are different from the natural notion of distance in the space of quantum states, i.e. the trace class norm. In this paper, we address such problem, finding relations between the rates of converg

Shota Gugushvili

Assuming that a stochastic process $X=(X_t)_{t\geq 0}$ is a sum of a compound Poisson process $Y=(Y_t)_{t\geq 0}$ with known intensity $λ$ and unknown jump size density $f,$ and an independent Brownian motion $Z=(Z_t)_{t\geq 0},$ we consider the problem of nonparametric estimation of $f$ from low frequency observations from $X.$ The estimator of $f$ is const

Arundhati Dasgupta

The entropy of apparent horizons is derived using coherent states or semiclassical states in quantum gravity. The leading term is proportional to area for large horizons, and the correction terms differ according to the details of the graph which is used to regularise the quantum gravity phase space variables.

Mihaly Bencze, Florentin Smarandache

In this paper we present 43 new inequalities related to integer part and fractional part.

Luis P. Chimento, Ruth Lazkoz

We investigate the link between the warp function and the potential in DBI cosmologies in connection with the possibility they represent power-law solutions. A prescription is given to take advantage of the known result that given a warp factor there is always a choice of potential resulting in a constant ratio between pressure and energy density. The method

Yingbin Liang, H. Vincent Poor, Shlomo Shamai

This paper summarizes recent contributions of the authors and their co-workers in the area of information-theoretic security.