May 2009 arXiv papers — page 20

A. I. Bogomazov, S. B. Popov

We consider the possible existence of a common channel of evolution of binary systems, which results in a gamma-ray burst during the formation of a black hole or the birth of a magnetar during the formation of a neutron star. We assume that the rapid rotation of the core of a collapsing star can be explained by tidal synchronization in a very close binary. T

Satoshi Shirai, Fuminobu Takahashi, T. T. Yanagida

We study a scenario that a hidden gaugino dark matter decays into the standard-model particles (and their supersymmetric partners) through a kinetic mixing with the gaugino of a U(1)B-L broken at a scale close to the grand unification scale. We show that decay of the hidden gaugino can explain excesses in the cosmic-ray electrons and positrons observed by PA

A. S. Alexandrov, A. M. Bratkovsky

Attractive electron correlations due to an electron-vibron interaction (EVI) can overcome the direct Coulomb repulsion of polarons in strongly deformable molecular quantum dots (MQDs). If it realizes, a switching appears in the I-V characteristics of the degenerate nonadiabatic molecular bridges weakly coupled to electrodes providing a route to ultrafast `me

Panagiotis Kotetes, Georgios Varelogiannis

In this paper we demonstrate the possibility of dissipationless spin transport in the chiral d-density wave state, by the sole application of a uniform Zeeman field gradient. The occurrence of these spontaneous spin currents is attributed to the parity (${\cal P}$) and time-reversal (${\cal T}$) violation induced by the $d_{xy}+id_{x^2-y^2}$ density wave ord

Nigel Hitchin

The Serre construction of rank two holomorphic bundles with a section is adapted to construct generalized holomorphic bundles on a generalized complex 4-manifold from the data of a set of points on an elliptic curve. The motivation is the special case of rank two Poisson modules on a complex surface with a holomorphic Poisson structure.

Jieci Wang, Qiyuan Pan, Songbai Chen, Jiliang Jing

The entanglement of the coupled massive scalar field in the spacetime of a Garfinkle-Horowitz-Strominger(GHS) dilaton black hole has been investigated. It is found that the entanglement does not depend on the mass of the particle and the coupling between the scalar field and the gravitational field, but it decreases as the dilaton parameter $D$ increases. It

P. Tisserand, P. R. Wood, J. B. Marquette, C. Afonso

R Coronae Borealis stars (RCB) are a rare type of evolved carbon-rich supergiant stars that are increasingly thought to result from the merger of two white dwarfs, called the Double degenerate scenario. This scenario is also studied as a source, at higher mass, of type Ia Supernovae (SnIa) explosions. Therefore a better understanding of RCBs composition woul

P. Busch, J. Kiukas, P. Lahti

The notion coexistence of quantum observables was introduced to describe the possibility of measuring two or more observables together. Here we survey the various different formalisations of this notion and their connections. We review examples illustrating the necessary degrees of unsharpness for two noncommuting observables to be jointly measurable (in one

Sudhanwa Patra, Anjishnu Sarkar, Utpal Sarkar, Urjit Yajnik

We propose a novel implementation of spontaneous parity breaking in supersymmetric left-right symmetric model, avoiding some of the problems encountered in previous studies. This implementation includes a bitriplet and a singlet, in addition to the bidoublets which extend the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM). The supersymmetri

Paul J. Hancock, Steven J. Tingay, Elaine M. Sadler, Chris Phillips

GHz-peaked spectrum (GPS) radio sources are thought to be young objects which later evolve into FR-I and FR-II radio galaxies. We have used the Australia Telescope 20GHz (AT20G) survey catalogue to select a uniform sample of GPS sources with spectral peaks above 5GHz, which should represent the youngest members of this class. In this paper, we present e-VLBI

Shi-Hsin Lin, Tatiana G. Rappoport, Mona Berciu, Boldizsar Janko

We investigate the effect of single and multiple impurities on the Zeeman-localized, spin polarized bound states in dilute magnetic semiconductor hybrid system. Such bound states appear whenever a dilute magnetic semiconductor showing giant Zeeman effect is exposed to an external magnetic field showing nanoscale inhomogeneity. We consider the specific exampl

T. J. Williams, A. A. Aczel, E. Baggio-Saitovitch, S. L. Budko

We have performed transverse field muon spin rotation measurements of single crystals of Ba(Fe$_{0.93}$Co$_{0.07})_2$As$_2$ with the applied magnetic field along the $\hat{c}$ direction. Fourier transforms of the measured spectra reveal an anisotropic lineshape characteristic of an Abrikosov vortex lattice. We have fit the $μ$SRSR spectra to a microscopic mo

M. Sharif, Bushra Majeed

In this paper, Killing vectors of spherically spacetimes have been evaluated in the context of teleparallel theory of gravitation. Further, we investigate the Killing vectors of the Friedmann metrics. It is found that for static spherically spacetimes the number of Killing vectors turn out to be \emph{seven} while for the Friedmann models, we obtain \emph{si

Pak-Wing Fok, Tom Chou

A Charge Transport (CT) mechanism has been proposed in several papers (e.g., Yavin, et al. PNAS, v102 3546 (2005)) to explain the localization of Base Excision Repair (BER) enzymes to lesions on DNA. The CT mechanism relies on redox reactions of iron-sulfur cofactors that modify the enzyme's binding affinity. These redox reactions are mediated by the DNA

Yajiang Hao, Shu Chen

We investigate the ground-state properties of two-component Bose gases confined in one-dimensional harmonic traps in the scheme of density-functional theory. The density-functional calculations employ a Bethe-ansatz-based local-density approximation for the correlation energy, which accounts for the correlation effect properly in the full physical regime. Fo

Hiroshi Oba, Masayuki Matsuo

We formulate a new scheme of the Hartree-Fock-Bogoliubov mean-field theory applicable to weakly bound and pair correlated deformed nuclei using the coordinate-space Green's function technique. On the basis of a coupled-channel representation of the quasiparticle wave function expanded in terms of the partial waves, we impose the correct boundary conditio

A. Verna, B. A. Davidson, Y. Szeto, A. Yu. Petrov

The performance of manganite-based magnetic tunnel junctions (MTJs) has suffered from reduced magnetization present at the junction interfaces that is ultimately responsible for the spin polarization of injected currents; this behavior has been attributed to a magnetic "dead layer" that typically extends a few unit cells into the manganite. X-ray mag

Onuttom Narayan, A. P. Young

We show that two commonly used definitions for the heat current give different results--through the Kubo formula--for the heat conductivity of oscillator chains. The difference exists for finite chains, and is expected to be important more generally for small structures. For a chain of N particles that are tethered at the ends, the ratio of the heat conducti

Muhammad Fainan Hanif, Peter J. Smith, Mansoor Shafi

In this paper we consider the capacity of the cognitive radio channel in a fading environment under a "low interference regime". This capacity depends critically on a power loss parameter, $α$, which governs how much transmit power the cognitive radio dedicates to relaying the primary message. We derive a simple, accurate approximation to $α$ which g

Andre H. Hoang, Ambar Jain, Ignazio Scimemi, Iain W. Stewart

Perturbation series in QCD are generally asymptotic and suffer from so-called infrared renormalon ambiguities. In the context of the standard operator product expansion in MS-bar these ambiguities are compensated by matrix elements of higher dimension operators, but the procedure can be difficult to control due to large numerical cancellations. Explicit subt

Arvind Rao, Alfred O. Hero, III

Disease occurs due to aberrant expression of genes and modulation of the biological pathways along which they lie. Inference of activated gene pathways, using gene expression data during disease progression, is an important problem. In this work, we have developed a generalizable framework for the identification of interacting pathways while incorporating bi

G. G. Pavlov, G. J. M. Luna

We present results of a recent Chandra X-ray Observatory observation of the central compact object (CCO) in the supernova remnant Cassiopeia A. This observation was obtained in an instrumental configuration that combines a high spatial resolution with a minimum spectral distortion, and it allowed us to search for pulsations with periods longer than 0.68 s. W

Chris Quigg

This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider. A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction of the electroweak theory is the existence

Jonathan Engle, Karim Noui, Alejandro Perez

Black holes in equilibrium can be defined locally in terms of the so-called isolated horizon boundary condition given on a null surface representing the event horizon. We show that this boundary condition can be treated in a manifestly SU(2) invariant manner. Upon quantization, state counting is expressed in terms of the dimension of Chern-Simons Hilbert spa

Khee-Gan Lee, Edo Berger, Gillian R. Knapp

We spectroscopically study the variability of H-alpha emission in mid- to late-M dwarfs on timescales of ~0.1-1 hr as a proxy for magnetic variability. About 80% of our sample exhibits statistically significant variability on the full range of timescales probed by the observations, and with amplitude ratios in the range of ~1.2-4. No events with an order of

F. Vazza, G. Brunetti, A. Kritsuk, R. Wagner

We have implemented an Adaptive Mesh Refinement criterion explicitly designed to increase spatial resolution around discontinuities in the velocity field in ENZO cosmological simulations. With this technique, shocks and turbulent eddies developed during the hierarchical assembly of galaxy clusters are followed with unprecedented spatial resolution, even at l

Michael Boyle, Abdul H. Mroué

Two complementary techniques are developed for obtaining the asymptotic form of gravitational-wave data at large radii from numerical simulations, in the form of easily implemented algorithms. It is shown that, without extrapolation, near-field effects produce errors in extracted waveforms that can significantly affect LIGO data analysis. The extrapolation t

Italo J. Dejter

The notion of a $\mathcal C$-ultrahomogeneous graph, due to Isaksen et al., is adapted for digraphs, and subsequently a strongly connected $\vec{C}_4$-ultrahomogeneous oriented graph on 168 vertices and 126 pairwise arc-disjoint 4-cycles is presented, with regular indegree and outdegree 3 and no circuits of lengths 2 and 3, by altering a definition of the Co

Jonathan L. Feng, Manoj Kaplinghat, Huitzu Tu, Hai-Bo Yu

Can dark matter be stabilized by charge conservation, just as the electron is in the standard model? We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact U(1) gauge symmetry of the hidden sector. Such candidates are predicted in WIMPless models, supersymmetric models i

Aleksey Cherman, Abhinav Nellore

We show that there are universal high-temperature relations for transport coefficients of plasmas described by a wide class of field theories with gravity duals. These theories can be viewed as strongly coupled large-Nc conformal field theories deformed by one or more relevant operators. The transport coefficients we study are the speed of sound and bulk vis

Joaquim Prades

I present the main results obtained in a recent work together with Eduardo de Rafael and Arkady Vainshtein on the hadronic light-by-light contribution to muon g-2. We came to the estimate a^{HLbL}_μ= (10.5 +- 2.6) x 10^{-10}. Here, some emphasis is put in pointing out where the future KLOE2 two-photon experimental program can help to reduce the present model

Fatima Araujo

In this work we study the existence of homogeneous Einstein metrics on the total space of homogeneous fibrations such that the fibers are totally geodesic manifolds. We obtain the Ricci curvature of an invariant metric with totally geodesic fibers and some necessary conditions for such a metric to be Einstein in terms of Casimir operators. Some particular ca

Yueheng Lan, Y. Charles Li

Sommerfeld paradox (turbulence paradox) roughly says that mathematically the Couette linear shear flow is linearly stable for all values of the Reynolds number, but experimentally transition from the linear shear to turbulence occurs under perturbations of any size when the Reynolds number is large enough. In [Li, Lin 2011], we offered a resolution of this p

Francesc Ferrer, Carlo Nipoti, Stefano Ettori

If the dark matter sector in the universe is composed by metastable particles, galaxies and galaxy clusters are expected to undergo significant secular evolution from high to low redshift. We show that the decay of dark matter, with a lifetime compatible with cosmological constraints, can be at the origin of the observed evolution of the Tully-Fisher relatio

CDF Collaboration, T. Aaltonen

We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector that correspond to an integrated luminosity of approximately 1.9 inverse fb. We select events consistent with a signature of a single cha

Jean Mairesse, Hoang-Thach Nguyen

Consider a Markovian Petri net with race policy. The marking process has a "product form" stationary distribution if the probability of viewing a given marking can be decomposed as the product over places of terms depending only on the local marking. First we observe that the Deficiency Zero Theorem of Feinberg, developped for chemical reaction netwo

Jeffrey Seely, Patrick Crotty

We report on a theoretical study showing that the leak conductance density, $\GL$, in the squid giant axon appears to be optimal for the action potential firing frequency. More precisely, the standard assumption that the leak current is composed of chloride ions leads to the result that the experimental value for $\GL$ is very close to the optimal value in t

Philipp Mertsch, Subir Sarkar

The excess in the positron fraction reported by the PAMELA collaboration has been interpreted as due to annihilation or decay of dark matter in the Galaxy. More prosaically, it has been ascribed to direct production of positrons by nearby pulsars, or due to pion production during stochastic acceleration of hadronic cosmic rays in nearby sources. We point out

Giovanni Gallavotti, Errico Presutti

The relation between thermostats of "isoenergetic" and "frictionless" kind is studied and their equivalence in the thermodynamic limit is proved in space dimension $d=1,2$ and, for special geometries, $d=3$.

Matthew Robert Ballard

We extend Orlov's result on representability of equivalences to schemes projective over a field. We also investigate the quasi-projective case.

Willem A. de Graaf

We describe two algorithms for finding representatives of the nilpotent orbits of a theta-group. The algorithms have been implemented in the computer algebra system GAP (inside the package SLA). We comment on their performance. We apply the algorithms to study the nilpotent orbits of theta-groups, where theta is an N-regular automorphism of a simple Lie alge

Jo Bovy, David W. Hogg, Sam T. Roweis

We generalize the well-known mixtures of Gaussians approach to density estimation and the accompanying Expectation--Maximization technique for finding the maximum likelihood parameters of the mixture to the case where each data point carries an individual $d$-dimensional uncertainty covariance and has unique missing data properties. This algorithm reconstruc

I. Bautista, L. Cunqueiro, J. Dias de Deus, C. Pajares

The collective interactions of many partons in the first stage of the collisions is the usual accepted explanation of the sizable elliptical flow. The clustering of color sources provides a framework of partonic interactions. In this scheme, we show a reasonable agreement with RHIC data for pT<1.5 GeV/c in both the dependence of v2 transverse momentum and in

Paul S. Aspinwall

The notion that the geometry of spacetime is given by the moduli space of 0-branes is examined in four examples of Calabi-Yau threefolds. An important consideration when determining the moduli space of D-branes is the stability condition and this is key in our analysis. In the first two examples, the flop and the orbifold blowup, no surprises are found. Next

Ayan Mahalanobis

The discrete logarithm problem is one of the backbones in public key cryptography. In this paper we study the discrete logarithm problem in the group of circulant matrices over a finite field. This gives rise to secure and fast public key cryptosystems.

Yevgeny Kazakov, Ian Pratt-Hartmann

Graded modal logic is the formal language obtained from ordinary (propositional) modal logic by endowing its modal operators with cardinality constraints. Under the familiar possible-worlds semantics, these augmented modal operators receive interpretations such as "It is true at no fewer than 15 accessible worlds that...", or "It is true at no more than 2 ac

CDF Collaboration, T. Aaltonen

We report the observation of the bottom, doubly-strange baryon Omega^-_b through the decay chain Omega^-_b -> J/psi Omega^-, where J/psi -> mu^+ mu^-, Omega^- -> Lambda K^-, and Lambda -> p pi^-, using 4.2 fb^{-1} of data from p\bar p collisions at sqrt{s}=1.96 TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability o

I. Deretzis, G. Forte, A. Grassi, A. La Magna

We implement a bottom-up multiscale approach for the modeling of defect localization in $C_{6n^2}H_{6n}$ islands, i.e. graphene quantum dots with a hexagonal symmetry, by means of density functional and semiempirical approaches. Using the \textit{ab initio} calculations as a reference, we recognize the theoretical framework under which semiempirical methods

C. Pankow, S. Klimenko, G. Mitselmakher, I. Yakushin

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed

Rimantas Lazauskas, Young-Ho Song, Tae-Sun Park

The cross section for radiative thermal neutron capture on ${}^{3}He$ ($\He3 +n \to \He4 +γ$; known as the $hen$ reaction) is calculated based on heavy-baryon chiral perturbation theory. The relevant M1 operators are derived up to next-to-next-to-next-to-leading order (N${}^3$LO). The initial and final nuclear wave functions are obtained from the rigorous Fa

Puxun Wu, Shuang Nan Zhang, Hongwei Yu

The emergent model in the context of loop quantum cosmology with a tachyon scalar field is studied. We find that there is a center equilibrium point in the semiclassical region and a saddle point in the classical region. If the potential of the tachyon field satisfies some conditions, the universe can stay at the center equilibrium point past-eternally and t

E. -M. Ilgenfritz, K. Jansen, M. P. Lombardo, M. Müller-Preußker

We present numerical results for the phase diagram of lattice QCD at finite temperature in the formulation with twisted mass Wilson fermions and a tree-level Symanzik-improved gauge action. Our simulations are performed on lattices with temporal extent N_τ=8, and lattice coupling βranging from strong coupling to the scaling domain. Covering a wide range in t

H. W. Diehl, Daniel Grüneberg

Euclidean $n$-component $ϕ^4$ theories whose Hamiltonians are O(n) symmetric except for quadratic symmetry breaking boundary terms are studied in films of thickness $L$. The boundary terms imply the Robin boundary conditions $\partial_nϕ_α=\mathring{c}^{(j)}_αϕ_α$ at the boundary planes $\mathfrak{B}_{j=1,2}$ at $z=0$ and $z=L$. Particular attention is paid

Tim Austin, Mariusz Lemanczyk

We show that under some natural ergodicity assumptions extensions given by Rokhlin cocycles lift the multiplier property if the associated locally compact group extension has only countably many L^\infty-eigenvalues. We make use of some analogs of basic results from the theory of finite-rank modules associated to an extension of measure-preserving systems in

Vinod M. Prabhakaran, Pramod Viswanath

The role of cooperation in managing interference - a fundamental feature of the wireless channel - is investigated by studying the two-user Gaussian interference channel where the source nodes can both transmit and receive in full-duplex. The sum-capacity of this channel is obtained within a gap of a constant number of bits. The coding scheme used builds up

John E. Proctor, Eugene Gregoryanz, Konstantin S. Novoselov, Mustafa Lotya

In-situ high pressure Raman spectroscopy is used to study monolayer, bilayer and few-layer graphene samples supported on silicon in a diamond anvil cell to 3.5 GPa. The results show that monolayer graphene adheres to the silicon substrate under compressive stress. A clear trend in this behaviour as a function of graphene sample thickness is observed. We also

H. Xu, B. S. Ham

Using light-induced localized surface plasmon interactions in a metamaterial, we present a plasmonic control of light absorption for photonic switching. We discuss that the present surface plasmon-induced photonic switching is comparable with coherence swapping in a tripod optical system based on electromagnetically induced transparency. This outcome opens a

J. Steinheimer, V. Dexheimer, H. Petersen, M. Bleicher

We investigate the influence of a deconfinement phase transition on the dynamics of hot and dense nuclear matter. We apply a hybrid model where an intermediate hydrodynamics stage is employed for the the hot and dense stage of a system created in head-on collisions of Pb+Pb/Au+Au at beam energies from $2-160A $GeV. The initial and final interactions are perf

Dirk Schuricht, Herbert Schoeller

We calculate the dynamical spin-spin correlation functions of a Kondo dot coupled to two noninteracting leads held at different chemical potentials. To this end we generalize a recently developed real-time renormalization group method in frequency space (RTRG-FS) to allow the calculation of dynamical correlation functions of arbitrary dot operators in system

Q. Li, Y. L. He, G. H. Tang, W. Q. Tao

In this brief report, a thermal lattice-Boltzmann (LB) model is presented for axisymmetric thermal flows in the incompressible limit. The model is based on the double-distribution-function LB method, which has attracted much attention since its emergence for its excellent numerical stability. Compared with the existing axisymmetric thermal LB models, the pre

Pradeep Kumar, Surajit Saha, C. R. Serrao, A. K. Sood

We have measured near normal incidence far infrared (FIR) reflectivity spectra of a single crystal of TbMnO3 from 10K to 300K in the spectral range of 50 cm$^{-1}$ to 700 cm$^{-1}$. Fifteen transverse optic (TO) and longitudinal optic (LO) modes are identified in the imaginary part of the dielectric function $ε_2$($ω$) and energy loss function Im(-1/$ε$($ω$)

N. J. G. Cross, R. S. Collins, N. C. Hambly, R. P. Blake

We present a description of the design and usage of a new synoptic pipeline and database model for time series photometry in the VISTA Data Flow System (VDFS). All UKIRT-WFCAM data and most of the VISTA main survey data will be processed and archived by the VDFS. Much of these data are multi-epoch, useful for finding moving and variable objects. Our new data

Rabin Banerjee, Shinichi Deguchi

A superspace approach to the Becchi-Rouet-Stora-Tyutin (BRST) formalism for the Yang-Mills theory on an n-dimensional unit sphere, S_1^{n}, is developed in a manifestly covariant manner based on the rotational supersymmetry characterized by the supergroup OSp(n+1|2). This is done by employing an (n+2)-dimensional unit supersphere, S_1^{n|2}, parametrized by

Gérard Ben Arous, Ivan Corwin

We consider the family of two-sided Bernoulli initial conditions for TASEP which, as the left and right densities ($ρ_-,ρ_+$) are varied, give rise to shock waves and rarefaction fans---the two phenomena which are typical to TASEP. We provide a proof of Conjecture 7.1 of [Progr. Probab. 51 (2002) 185--204] which characterizes the order of and scaling functio

Frank Deppisch, Olaf Kittel

We study CP asymmetries in two-body decays of top squarks into neutralinos and sleptons at the LHC. These asymmetries are used to probe the CP phases possibly present in the stop and neutralino sector of the Minimal Supersymmetric Standard Model. Taking into account bounds from experimental electric dipole moment searches, we identify areas in the mSUGRA par

Niklas Brännström, Emiliano De Simone, Vassili Gelfreich

We study a class of slow-fast Hamiltonian systems with any finite number of degrees of freedom, but with at least one slow one and two fast ones. At $% ε=0$ the slow dynamics is frozen. We assume that the frozen system (i.e. the unperturbed fast dynamics) has families of hyperbolic periodic orbits with transversal heteroclinics. For each periodic orbit we de

Sung Hoon Lim, Young-Han Kim, Sae-Young Chung

Motivated by fading channels and erasure channels, the problem of reliable communication over deterministic relay networks is studied, in which relay nodes receive a function of the incoming signals and a random network state. An achievable rate is characterized for the case in which destination nodes have full knowledge of the state information. If the rela

Nigel P. Byott

Let S/R be a finite extension of discrete valuation rings of characteristic p>0, and suppose that the corresponding extension L/K of fields of fractions is separable and is H-Galois for some K-Hopf algebra H. Let D_{S/R} be the different of S/R. We show that if S/R is totally ramified and its degree n is a power of p, then any element $ρ$ of L with $v_L(ρ)$

M. Hirsch, S. Morisi, J. W. F. Valle

We consider tri-bimaximal lepton mixing within low-scale seesaw schemes where light neutrino masses arise from TeV scale physics, potentially accessible at the Large Hadron Collider (LHC). Two examples are considered, based on the A4 flavor symmetry realized within the inverse or the linear seesaw mechanisms. Both are highly predictive so that in both the li

Baptiste Billaud, Marco Picco, Tuong T. Truong

We present a theoretical variational approach, based on the effective mass approximation (EMA), to study the quantum-confinement Stark effects for spherical semiconducting quantum dots in the strong confinement regime of interactive electron-hole pair and limiting weak electric field. The respective roles of the Coulomb potential and the polarization energy

Masanori Hanada, Lorenzo Mannelli, Yoshinori Matsuo

We consider a supersymmetric matrix quantum mechanics. This is obtained by adding Myers and mass terms to the dimensional reduction of 4d N=1 super Yang-Mills theory to one dimension. Using this model we construct 4d N=1 super Yang-Mills theory in the planar limit by using the Eguchi-Kawai equivalence. The same matrix quantum mechanics is also used to provid

Zheng-Tao Wei, Hong-Wei Ke, Xiao-Feng Yang

The recent measurement on the decay constant of $D_s$ shows a discrepancy between theory and experiment. We study the leptonic and semileptonic decays of $D$ and $D_s$ simultaneously within the standard model by employing a lightfront quark model. There is space by tuning phenomenological parameters which can explain the &#34;$f_{D_s}$ puzzle&#34; and do not

M. Nomura, N. Kumagai, S. Iwamoto, Y. Ota

Strong coupling of photons and materials in semiconductor nanocavity systems has been investigated because of its potentials in quantum information processing and related applications, and has been testbeds for cavity quantum electrodynamics (QED). Interesting phenomena such as coherent exchange of a single quantum between a single quantum dot and an optical

E. Khomenko, M. Collados

We suggest an explanation for the high-frequency power excess surrounding active regions known as seismic halos. The idea is based on numerical simulations of magneto-acoustic waves propagation in sunspots. We propose that such an excess can be caused by the additional energy injected by fast mode waves refracted in the higher atmosphere due to the rapid inc

Eugen Schweitzer

In different passages of his dialogues, Plato showed deep mathematically-based physical insights. Regrettably most readers overlooked the respective statements, or they utterly did not understand those hints since they were full of philological fallacious terms. Respectable translators misinterpreted such statements and therefore Plato&#39;s respective remar

Jai Grover, Jan B. Gutowski, Carlos A. R. Herdeiro, Patrick Meessen

Solutions of five-dimensional De Sitter supergravity admitting Killing spinors are considered, using spinorial geometry techniques. It is shown that the &#34;null&#34; solutions are defined in terms of a one parameter family of 3-dimensional constrained Einstein-Weyl spaces called Gauduchon-Tod structures. They admit a geodesic, expansion-free, twist-free an

Pascal Anastasopoulos, Elias Kiritsis, Andrea Lionetto

We analyze the problem of the hierarchy of masses and mixings in orientifold realizations of the Standard Model. We find bottom-up brane configurations that can generate such hierarchies.

F. Martinelli, F. Toninelli

We consider the Glauber dynamics for the 2D Ising model in a box of side L, at inverse temperature $β$ and random boundary conditions $τ$ whose distribution P either stochastically dominates the extremal plus phase (hence the quotation marks in the title) or is stochastically dominated by the extremal minus phase. A particular case is when P is concentrated

Nan Li, Da-Ming Chen

Cosmological numerical simulations of galaxy formation have led to the cuspy density profile of a pure cold dark matter halo toward the center, which is in sharp contradiction with the observations of the rotation curves of cold dark matter-dominated dwarf and low surface brightness disk galaxies, with the latter tending to favor mass profiles with a flat ce

Muhammad Fainan Hanif, Peter J. Smith, Mansoor Shafi

In this paper we describe the effect of imperfections in the radio environment map (REM) information on the performance of cognitive radio (CR) systems. Via simulations we explore the relationship between the required precision of the REM and various channel/system properties. For example, the degree of spatial correlation in the shadow fading is a key facto

Mahender Singh

We show that the inverse limit and the orbit map commute for actions of compact groups on compact Hausdorff spaces.

Muhammad Fainan Hanif, Mansoor Shafi, Peter J. Smith, Pawel A. Dmochowski

In this paper we describe a model for calculating the aggregate interference encountered by primary receivers in the presence of randomly placed cognitive radios (CRs). We show that incorporating the impact of distance attenuation and lognormal fading on each constituent interferer in the aggregate, leads to a composite interference that cannot be satisfacto

Francesco Fidaleo, Farrukh Mukhamedov

We show that some $C^*$--dynamical systems obtained by &#34;quantizing&#34; classical ones on the free Fock space, enjoy very strong ergodic properties. Namely, if the classical dynamical system $(X, T, \m)$ is ergodic but not weakly mixing, then the resulting quantized system $(\gg,\a)$ is uniquely ergodic (w.r.t the fixed point algebra) but not uniquely we

Jae-Hyouk Lee

In this article, we research on the correspondences between the geometry of del Pezzo surfaces S_{r} and the geometry of Gosset polytopes (r-4)_{21}. We construct Gosset polytopes (r-4)_{21} in Pic S_{r}; Q whose vertices are lines, and we identify divisor classes in Pic S_{r} corresponding to (a-1)-simplexes, (r-1)-simplexes and (r-1)-crosspolytopes of the

Emanuele Berti, Vitor Cardoso, Andrei O. Starinets

Quasinormal modes are eigenmodes of dissipative systems. Perturbations of classical gravitational backgrounds involving black holes or branes naturally lead to quasinormal modes. The analysis and classification of the quasinormal spectra requires solving non-Hermitian eigenvalue problems for the associated linear differential equations. Within the recently d

Saharon Shelah

We deal with relatives of GCH which are provable. In particular we deal with rank version of the revised GCH. Our motivation was to find such results when only weak versions of the axiom of choice are assumed but some of the results gives us additional information even in ZFC.

Yen-Chih Lin, J. M. Sun, H. W. Yang, C. L. Wang

A three-dimensional X-ray tomography is performed to investigate the internal structure and its evolution of a crumpled aluminum foil. The upper and lower bounds of the internal geometric fractal dimension are determined, which increase with the compression. Contrary to the simulation results, we find that the mass distribution changes from being inhomogeneo

Albert C. Fannjiang

The problem of imaging extended targets (sources or scatterers) is formulated in the framework of compressed sensing with emphasis on subwavelength resolution. The proposed formulation of the problems of inverse source/scattering is essentially exact and leads to the random partial Fourier measurement matrix. In the case of square-integrable targets, the pro

Carlos Hernandez-Monteagudo, Rashid A. Sunyaev

It is well known that Thomson scattering of CMB photons in galaxy clusters introduces new anisotropies in the CMB radiation field, but however little attention is payed to the fraction of CMB photons that are scattered off the line of sight, causing a slight blurring of the CMB anisotropies present at the moment of scattering. In this work we study this {\it

Masanobu Kaneko, Hironori Matsuo

This paper has been withdrawn by the authors due to the fact that the conjecture has indeed already long been established.

Masanobu Kaneko

We define &#34;values&#34; of the elliptic modular j-function at real quadratic irrationalities by using Hecke&#39;s hyperbolic Fourier expansions, and present some observations based on numerical experiments.

Bob Coecke, Eric Oliver Paquette

In this chapter we survey some particular topics in category theory in a somewhat unconventional manner. Our main focus will be on monoidal categories, mostly symmetric ones, for which we propose a physical interpretation. These are particularly relevant for quantum foundations and for quantum informatics. Special attention is given to the category which has

Joseph Coffey, Liat Kessler, Alvaro Pelayo

Let (M,ω) be a symplectic manifold, and Sigma a compact Riemann surface. We define a 2-form on the space of immersed symplectic surfaces in M, and show that the form is closed and non-degenerate, up to reparametrizations. Then we give conditions on a compatible almost complex structure J on (M,ω) that ensure that the restriction of the form to the moduli spa

Takaho Miura, Hideyoshi Arakida, Masumi Kasai, Shuichi Kuramata

We give an idea and the order-of-magnitude estimations to explain the recently reported secular increase of the Astronomical Unit (AU) by Krasinsky and Brumberg (2004). The idea proposed is analogous to the tidal acceleration in the Earth-Moon system, which is based on the conservation of the total angular momentum and we apply this scenario to the Sun-plane

Rajib Rahman, Seung H. Park, Timothy B. Boykin, Gerhard Klimeck

The dependence of the g-factors of semiconductor donors on applied electric and magnetic fields is of immense importance in spin based quantum computation and in semiconductor spintronics. The donor g-factor Stark shift is sensitive to the orientation of the electric and magnetic fields and strongly influenced by the band-structure and spin-orbit interaction

Allan Sandage

A new reduction is made of the HST photometric data for E galaxies in three remote clusters at redshifts near z=0.85 in search for the Tolman surface brightness (SB) signal for the reality of the expansion. Because of the strong variation of SB of such galaxies with intrinsic size, and because the Tolman test is about surface brightness, we must account for

David S. Herscovici, Benjamin D. Hester, Glenn H. Hurlbert

We investigate generalizations of pebbling numbers and of Graham&#39;s pebbling conjecture that pi(GxH) <= pi(G)pi(H), where pi(G) is the pebbling number of the graph G. We develop new machinery to attack the conjecture, which is now twenty years old. We show that certain conjectures imply others that initially appear stronger. We also find counterexamples t

C. Anteneodo, R. Riera

Real data are constrained to finite sampling rates, which calls for a suitable mathematical description of the corrections to the finite-time estimations of the dynamic equations. Often in the literature, lower order discrete time approximations of the modeling diffusion processes are considered. On the other hand, there is a lack of simple estimating proced

Adi Armoni, Amit Giveon, Dan Israel, Vasilis Niarchos

We study a three-dimensional U(k) Yang-Mills Chern-Simons theory with adjoint matter preserving two supersymmetries. According to Acharya and Vafa, this theory describes the low-energy worldvolume dynamics of BPS domain walls in four-dimensional N=1 SYM theory. We demonstrate how to obtain the same theory in a brane configuration of type IIB string theory th

V. B. Nascimento, Ang Li, Dilushan R. Jayasundara, Yi Xuan

BaFe2As2 exhibits properties characteristic of the parent compounds of the newly discovered iron (Fe)-based high-TC superconductors. By combining the real space imaging of scanning tunneling microscopy/spectroscopy (STM/S) with momentum space quantitative Low Energy Electron Diffraction (LEED) we have identified the surface plane of cleaved BaFe2As2 crystals