April 2009 arXiv papers — page 38

Liling Sun, Takahiro Matsuoka, Yasuyuki Tamari, Katsuya Shimizu

We report high-pressure induced superconductivity in boron nanowires (BNWs) with rhombohedral crystal structure. Obviously different from bulk rhombohedral boron, these BNWs show a semiconductor-metal transition at much lower pressure than bulk boron. Also, we found these BNWs become superconductors with Tc=1.5 K at 84 GPa, at the pressure of which bulk boro

Sergey K. Sekatskii, Stefano Beltraminelli, Danilo Merlini

This paper is a continuation of our recent paper with the same title, arXiv:0806.1596v1 [math.NT], where a number of integral equalities involving integrals of the logarithm of the Riemann zeta-function were introduced and it was shown that some of them are equivalent to the Riemann hypothesis. A few new equalities of this type are established; contrary to t

Long-Bao Yu, Zheng-Yuan Xue, Z. D. Wang, Yang Yu

The interaction between a superconducting phase qubit and the two-level systems locating inside the Josephson tunnel barrier is shown to be described by the XY model, which is naturally used to implement the iSWAP gate. With this gate, we propose a scheme to efficiently generate genuine multi-qubit entangled states of such two-level systems, including multip

Laurent Ducrohet

We study stable rank 2 vector bundles with trivial determinant whose Frobenius pull back is non stable over a general curve of genus g>1. In genus 2, we apply recent results about the theta divisor associated to the bundle B of locally exact differential forms and we derive a scheme-theoretic description of the Frobenius inverse image of the semi-stable boun

Andreas Degner, Rainer Verch

The recently proposed states of low energy provide a well-motivated class of reference states for the quantized linear scalar field on cosmological Friedmann-Robertson-Walker spacetimes. The low energy property of a state is localized close to some value of the cosmological time coordinate. We present calculations of the relative cosmological particle produc

J. E. Sprittles, Y. D. Shikhmurzaev

It is known from both experiments and molecular dynamics simulations that chemically patterning a solid surface has an effect on the flow of an adjacent liquid. This fact is in stark contrast with predictions of classical fluid mechanics where the no-slip boundary condition is insensitive to the chemistry of the solid substrate. It has been shown that the in

A. Sulaksono, T. J. Buervenich, P. -G. Reinhard, J. A. Maruhn

Based on the properties of the critical and the actual effective masses of sigma and omega mesons, criteria to estimate the values of the isoscalar nonlinear terms of the standard relativistic mean field model that reproduce stable equations of state in respect to particle hole excitation at high densities are derived. The relation between nuclear matter sta

Patrick Schiavone, Fabrice Chassat, Thomas Boudou, Emmanuel Promayon

The brain deformation that occurs during neurosurgery is a serious issue impacting the patient "safety" as well as the invasiveness of the brain surgery. Model-driven compensation is a realistic and efficient solution to solve this problem. However, a vital issue is the lack of reliable and easily obtainable patient-specific mechanical characteristic

Marek Karaś

Let d_3 >= p_2 > p_1 >= 3 be integers such that p_1,p_2 are prime numbers. In this paper we show that the sequence (p_1,p_2,d_3) is the multidegree of some tame automorphisms of C^3 if and only if d_3 is in p_1*N+p_2*N, i.e. if and only if d_3 is a linear combination of p_1 and p_2 with coefficients in N.

Marek Karaś

Let F=(F_1,...,F_n):C^n --> C^n be any polynomial mapping. By multidegree of F, denoted mdeg F, we call the sequence of positive integers (deg F_1,...,F_n). In this paper we addres the following problem: for which sequence (d_1,...,d_n) there is an automorphism or tame automorphism F:C^n --> C^n with mdeg F=(d_1,...,d_n}. We proved, among other things, that

Tatsuhiko Yagasaki

In this paper we introduce a general notion of weak extension property for embeddings induced by a group actions. As an example, for the group H(M, m) of measure-preserving homeomorphisms of a noncompact manifold M, we deduce weak type extension theorems, and as an application we exhibit the local contractibility of the group H_c(M, m) of measure-preserving

M. Mortazavimanesh, Morteza Mohseni

After considering the reference case of the motion of spinning test bodies in the equatorial plane of the Schwarzschild space-time, we generalize the results to the case of the motion of a spinning particle in the equatorial plane of the Schwarzschild-de Sitter space-time. Specifically, we obtain the loci of turning points of the particle in this plane. We s

Mitsuru Toishi, Dirk Englund, Andrei Faraon, Jelena Vuckovic

We analyze a single photon source consisting of an InAs quantum dot coupled to a directional-emission photonic crystal (PC) cavity implemented in GaAs. On resonance, the dot's lifetime is reduced by more than 10 times, to 45ps. Compared to the standard three-hole defect cavity, the perturbed PC cavity design improves the collection efficiency into an obj

G. S. Weiss, G. Zhang

We consider the singular perturbation problem $$ Δu_ε=β_ε(u_ε), $$ where $β_ε(s)=\frac{1}εβ(\frac{s}ε)$, $β$ is a Lipschitz continuous function such that $β>0$ in $(0, 1)$, $β\equiv 0$ outside $(0, 1)$ and $\int_0^1β(s) ds={1/2}$. We construct an example exhibiting a {\em degenerate singularity} as $ε_k\searrow 0$. More precisely, there is a sequence of solu

D. Hsieh, Y. Xia, D. Qian, L. Wray

Electron systems that possess light-like dispersion relations or the conical Dirac spectrum, such as graphene and bismuth, have recently been shown to harbor unusual collective states in high magnetic fields. Such states are possible because their light-like electrons come in spin pairs that are chiral,which means that their direction of propagation is tied

P. Udomsamuthirun, R. Peamsuwan, C. Kumvongsa

The effect of anisotropic order parameter to specific heat of anisotropic two-band superconductors in BCS weak-coupling limit are investigated. An analytical specific heat jump and the numerical specific heat are shown by using anisotropic order parameters, and the electron-phonon interaction and non-electron-phonon interaction. The two model of anisotropic

Vic Patrangenaru

One shows that Cartan's method of adapted frames in Chapter XII of his famous treatise of Riemannian geometry, leads to a classification theorem of homogeneous Riemannian manifolds. Examples of classification in 3D dimensions obtained by Cartan are given using this powerful method.

Ciprian Demeter, Malabika Pramanik, Christoph Thiele

We prove bounds for multilinear operators on $\R^d$ given by multipliers which are singular along a $k$ dimensional subspace. The new case of interest is when the rank $k/d$ is not an integer. Connections with the concept of {\em true complexity} from Additive Combinatorics are also investigated.

E. Loginova, N. C. Bartelt, P. J. Feibelman, K. F. McCarty

Graphene forms from a relatively dense, tightly-bound C-adatom gas, when elemental C is deposited on or segregates to the Ru(0001) surface. Nonlinearity of the graphene growth rate with C adatom density suggests that growth proceeds by addition of C atom clusters to the graphene edge. The generality of this picture has now been studied by use of low-energy e

M. Khodas, I. A. Zaliznyak, D. E. Kharzeev

Atomically thin two-dimensional layer of honeycomb crystalline carbon known as graphene is a promising system for electronics. It has a point-like Fermi surface, which is very sensitive to external potentials. In particular, Zeeman magnetic field parallel to the graphene layer splits electron bands and creates fully spin-polarized and geometrically congruent

R. F. Goldin, S. Tolman

The main purpose of this article is to extend some of the ideas from Schubert calculus to the more general setting of Hamiltonian torus actions on compact symplectic manifolds with isolated fixed points. Given a generic component of the moment map, we define a canonical class α_p in the equivariant cohomology of the manifold M for each fixed point p of M. Wh

Raffaele Bruno, Vania Conan, Stephane Rousseau

Full exploitation of the bandwidth resources of Wireless Networks is challenging because of the sharing of the radio medium among neighboring nodes. Practical algorithms and distributed schemes that tries to optimising the use of the network radio resources. In this technical report we present the proof that maximising the network capacity is is an APX Compl

E. van Heumen, E. Muhlethaler, A. B. Kuzmenko, H. Eisaki

We take advantage of the connection between the free carrier optical conductivity and the glue function in the normal state, to reconstruct from the infrared optical conductivity the glue-spectrum of ten different high-Tc cuprates revealing a robust peak in the 50-60 meV range and a broad con- tinuum at higher energies for all measured charge carrier concent

Ron Donagi, Martijn Wijnholt

F-theory admits 7-branes with exceptional gauge symmetries, which can be compactified to give phenomenological four-dimensional GUT models. Here we study general supersymmetric compactifications of eight-dimensional Yang-Mills theory. They are mathematically described by meromorphic Higgs bundles, and therefore admit a spectral cover description. This allows

Ignas A. G. Snellen, Ernst J. W. de Mooij, Simon Albrecht

Hot Jupiters are a class of extrasolar planet that orbit their parent stars at very short distances. Due to their close proximity, they are expected to be tidally locked, which can lead to a large temperature difference between their day and nightsides. Infrared observations of eclipsing systems have yielded dayside temperatures for a number of transiting pl

Kang Ning, Hon Wai Leong

Sequences set is a mathematical model used in many applications. As the number of the sequences becomes larger, single sequence set model is not appropriate for the rapidly increasing problem sizes. For example, more and more text processing applications separate a single big text file into multiple files before processing. For these applications, the underl

Xue-Ning Bai, Jeremy Goodman

Requirements for magnetic coupling and accretion in the active layer of a protostellar disk are re-examined, and some implications for thermal emission from the layer are discussed. The ionization and electrical conductivity are calculated following the general scheme of Ilgner and Nelson but with an updated UMIST database of chemical reactions and some impr

E. Khatami, C. R. Lee, Z. J. Bai, R. T. Scalettar

Dynamical mean field theory and its cluster extensions provide a very useful approach for examining phase transitions in model Hamiltonians, and, in combination with electronic structure theory, constitute powerful methods to treat strongly correlated materials. The key advantage to the technique is that, unlike competing real space methods, the sign problem

A. T. Hatke, M. A. Zudov, L. N. Pfeiffer, K. W. West

We study the temperature evolution of the non-linear oscillatory magnetoresistance in a high-mobility two-dimensional electron system subject to a strong dc electric field. We find that the decay of the oscillation amplitude with increasing temperature originates primarily from increasing quantum scattering rate entering the Dingle factor. We attribute this

Mark Herrera, David C. Roberts, Natali Gulbahce

Despite the apparent cross-disciplinary interactions among scientific fields, a formal description of their evolution is lacking. Here we describe a novel approach to study the dynamics and evolution of scientific fields using a network-based analysis. We build an idea network consisting of American Physical Society Physics and Astronomy Classification Schem

E. Berg, E. Fradkin, S. A. Kivelson

A number of spectacular experimental anomalies\cite{li-2007,fujita-2005} have recently been discovered in certain cuprates, notably {\LBCO} and {\LNSCO}, which exhibit unidirectional spin and charge order (known as ``stripe order''). We have recently proposed to interpret these observations as evidence for a novel ``striped superconducting''

V. Teodorescu, R. Winkler

The spin-dependent elastic reflection of quasi two-dimensional electrons from a lateral impenetrable barrier in the presence of band-structure spin-orbit coupling results in a spin angular impulse exerted on the electrons which is proportional to the nontrivial difference between the electrons' momentum and velocity. Even for an unpolarized incoming beam

Cyril Houdayer, Dimitri Shlyakhtenko

Using an extension of techniques of Ozawa and Popa, we give an example of a non-amenable strongly solid $\rm{II}_1$ factor $M$ containing an "exotic" maximal abelian subalgebra $A$: as an $A$,$A$-bimodule, $L^2(M)$ is neither coarse nor discrete. Thus we show that there exist $\rm{II}_1$ factors with such property but without Cartan subalgebras. It also foll

O. V. Dolgov, A. A. Golubov, D. Parker

We consider a two-band superconductor with relative phase $π$ between the two order parameters as a model for the superconducting state in ferropnictides. Within this model we calculate the microwave response and the NMR relaxation rate. The influence of intra- and interband impurity scattering beyond the Born and unitary limits is taken into account. We sho

S. M. Giampaolo, G. Adesso, F. Illuminati

We investigate the existence and the properties of fully separable (fully factorized) ground states in quantum spin systems. Exploiting techniques of quantum information and entanglement theory we extend a recently introduced method and construct a general, self-contained theory of ground state factorization in frustration free quantum spin models defined on

Brian Feldstein

We reconsider the possibility of violating the generalized second law of thermodynamics in theories with spontaneous Lorentz violation. It has been proposed that this may be accomplished in particular with a black hole immersed in a ghost condensate background, which may be taken to break Lorentz invariance without appreciably distorting the space-time geome

Alexander V. Belikov, Dan Hooper

Although empirical evidence indicates that that the universe's gas had become ionized by redshift z ~ 6, the mechanism by which this transition occurred remains unclear. In this article, we explore the possibility that dark matter annihilations may have played the dominant role in this process. Energetic electrons produced in these annihilations can scat

Samaya Nissanke, Daniel E. Holz, Scott A. Hughes, Neal Dalal

Recent observations support the hypothesis that a large fraction of "short-hard" gamma-ray bursts (SHBs) are associated with compact binary inspiral. Since gravitational-wave (GW) measurements of well-localized inspiraling binaries can measure absolute source distances, simultaneous observation of a binary's GWs and SHB would allow us to independ

Oleg Bogopolski, Konstantin Sviridov

We will say that a group G possesses the Magnus property if for any two elements u,v in G with the same normal closure, u is conjugate to v or v^{-1}. We prove that some one-relator groups, including the fundamental groups of closed nonorientable surfaces of genus g>3 possess this property. The analogous result for orientable surfaces of any finite genus was

Daniel Cavalcanti, Rafael Chaves, Leandro Aolita, Luiz Davidovich

We consider graph states of arbitrary number of particles undergoing generic decoherence. We present methods to obtain lower and upper bounds for the system's entanglement in terms of that of considerably smaller subsystems. For an important class of noisy channels, namely the Pauli maps, these bounds coincide and thus provide the exact analytical expres

K G Arun, Clifford M Will

Observations by laser interferometric detectors of gravitational waves from inspiraling compact binary systems can be used to search for a dependence of the waves' propagation speed on wavelength, and thereby to bound the mass or Compton wavelength of a putative graviton. We study the effect of including higher harmonics, as well as their post-Newtonian

Rachel A. Rampy, David M. Smith, Ignacio Negueruela

We present the first direct evidence for dense clumps of matter in the companion wind in a Supergiant Fast X-ray Transient (SFXT) binary. This is seen as a brief period of enhanced absorption during one of the bright, fast flares that distinguish these systems. The object under study was IGR J17544-2619, and a total of 236 ks of data were accumulated with th

Jae-Seung Jeong, Hyun-Woo Lee

Structure of the spin-orbit coupling varies from material to material and thus finding the correct spin-orbit coupling structure is an important step towards advanced spintronic applications. We show theoretically that the curvature in a carbon nanotube generates two types of the spin-orbit coupling, one of which was not recognized before. In addition to the

Kohtaro Tadaki

Chaitin [G. J. Chaitin, J. Assoc. Comput. Mach., vol.22, pp.329-340, 1975] introduced \Omega number as a concrete example of random real. The real \Omega is defined as the probability that an optimal computer halts, where the optimal computer is a universal decoding algorithm used to define the notion of program-size complexity. Chaitin showed \Omega to be r

Artur Scherer, Regina B. Howard, Barry C. Sanders, Wolfgang Tittel

Entanglement swapping between photon pairs is a fundamental building block in schemes using quantum relays or quantum repeaters to overcome the range limits of long-distance quantum key distribution. We develop a closed-form solution for the actual quantum states prepared by realistic entanglement swapping, which takes into account experimental deficiencies

Thomas Becher, Matthias Neubert

A formula for the two-loop infrared singularities of dimensionally regularized QCD scattering amplitudes with an arbitrary number of massive and massless legs is derived. The singularities are obtained from the solution of a renormalization-group equation, and factorization constraints on the relevant anomalous-dimension matrix are analyzed. The simplicity o

Fredrik Johansson, Gregory F. Lawler

We prove an upper bound on the optimal H\"older exponent for the chordal SLE path parameterized by capacity and thereby establish the optimal exponent as conjectured by J. Lind. We also give a new proof of the lower bound. Our proofs are based on the sharp estimates of moments of the derivative of the inverse map. In particular, we improve an estimate of the

M. Bertola, S. Y. Lee, M. Y. Mo

We consider the unitary matrix model in the limit where the size of the matrices become infinite and in the critical situation when a new spectral band is about to emerge. In previous works the number of expected eigenvalues in a neighborhood of the band was fixed and finite, a situation that was termed "birth of a cut" or "first colonization&#34

H. J. Im, T. Ito, H. Miyazaki, S. Kimura

Ce 3d-4f resonant angle-resolved photoemission measurements on CeCoGe$_{1.2}$Si$_{0.8}$ and CeCoSi$_{2}$ have been performed to understand the Fermi surface topology as a function of hybridization strength between Ce 4$f$- and conduction electrons in heavy-fermion systems. We directly observe that the hole-like Ce 4$f$-Fermi surfaces of CeCoSi$_{2}$ is small

Mark M. Wilde, Min-Hsiu Hsieh

We introduce a new protocol, the channel-state coding protocol, to quantum Shannon theory. This protocol generates entanglement between a sender and receiver by coding for a noisy quantum channel with the aid of a noisy shared state. The mother and father protocols arise as special cases of the channel-state coding protocol, where the channel is noiseless or

Avraham Gal

Explicit expressions for the parity-violating s-wave and the parity-conserving p-wave contributions to pi- weak-decay rates of Lambda hypernuclei in the 1p shell are given in the weak-coupling limit, to update previous shell-model calculations and to compare with recent pi- spectra and total decay rates measured by the FINUDA Collaboration. A useful sum rule

S. Bhattacharya, A. Milchev, V. G. Rostiashvili, T. A. Vilgis

The thermally assisted detachment of a self-avoiding polymer chain from an adhesive surface by an external force applied to one of the chain ends is investigated. We perform our study in the "fixed height" statistical ensemble where one measures the fluctuating force, exerted by the chain on the last monomer when a chain end is kept fixed at height $

Nathalie Krell, Alain Rouault

The main focus of this work is the asymptotic behavior of mass-conservative homogeneous fragmentations. Considering the logarithm of masses makes the situation reminiscent of branching random walks. The standard approach is to study {\bf asymptotical} exponential rates. For fixed $v > 0$, either the number of fragments whose sizes at time $t$ are of order $\

Sylvain Brochard

We prove some finiteness theorems for the Picard functor of an algebraic stack, in the spirit of SGA 6, exp. XII and XIII. In particular, we give a stacky version of Raynaud's relative representability theorem, we give sufficient conditions for the existence of the torsion component of the Picard functor, and for the finite generation of the Neron-Severi

Li-Lu Zhao, Zhi-Wei Sun

Let n be a positive odd integer and let p>n+1 be a prime. We mainly derive the following congruence: $$\sum_{0<i_1<...<i_n<p}(i_1/3)(-1)^{i_1}/(i_1...i_n)=0 (mod p).$$

Emilie Dufresne, Jonathan Elmer, Martin Kohls

In the case of finite groups, a separating algebra is a subalgebra of the ring of invariants which separates the orbits. Although separating algebras are often better behaved than the ring of invariants, we show that many of the criteria which imply that the ring of invariants is non Cohen-Macaulay actually imply that no graded separating algebra is Cohen-Ma

Bin Gong, Jian-Xiong Wang

We calculate the next-to-leading-order (NLO) QCD correction to $e^+e^-\to J/ψc \bar{c}$ at the B factories, and present theoretical predictions on the momentum and production angular distribution for $J/ψ$ production, and momentum distribution for $J/ψ$ polarization at NLO for the first time. By applying Brodsky, Lepage and Mackenzie scale setting for the re

Jordi Mur-Petit

We study the dynamics of a trapped spin-1 condensate in a magnetic field. First, we analyze the homogeneous system, for which the dynamics can be understood in terms of orbits in phase space. We analytically solve for the dynamical evolution of the populations of the various Zeeman components of the homogeneous system. This result is then applied via a local

Zohar Komargodski, Nathan Seiberg

A careful analysis of the Fayet-Iliopoulos (FI) model shows that its energy momentum tensor and supersymmetry current are not gauge invariant. Since the corresponding charges are gauge invariant, the model is consistent. However, our observation about the currents gives a new perspective on its restrictive renormalization group flow and explains why FI-terms

Jinkui Wan

We classify and construct irreducible completely splittable representations of affine and finite Hecke-Clifford algebras over an algebraically closed field of characteristic not equal to 2.

A. M. Kadigrobov, S. Andersson, D. Radic, R. I. Shekhter

We investigate the interplay between the thermodynamic properties and spin-dependent transport in a mesoscopic device based on a magnetic multilayer (F/f/F), in which two strongly ferromagnetic layers (F) are exchange-coupled through a weakly ferromagnetic spacer (f) with the Curie temperature in the vicinity of room temperature. We show theoretically that t

Hirokazu Nishimura

Frolicher and Nijenhuis recognized well in the middle of the previous century that the Lie bracket and its Jacobi identity could and should exist beyond Lie algebras. Nevertheless the conceptual meaning of their discovery has been obscured by the messy techniques they exploited. The principal objective in this paper is to show that the double dualization fun

Ivan Nourdin, Giovanni Peccati, Gesine Reinert

We compute explicit bounds in the normal and chi-square approximations of multilinear homogenous sums (of arbitrary order) of general centered independent random variables with unit variance. In particular, we show that chaotic random variables enjoy the following form of universality: (a) the normal and chi-square approximations of any homogenous sum can be

T. M. Janssen, S. P. Miao, T. Prokopec, R. P. Woodard

We generalize the effective potential to scalar field configurations which are proportional to the Hubble parameter of a homogeneous and isotropic background geometry. This may be useful in situations for which curvature effects are significant. We evaluate the one loop contribution to the Hubble Effective Potential for a massless scalar with arbitrary confo

Stefan Weinzierl

This paper gives detailed information on the structure of the infrared singularities for the process e+ e- --> 3 jets at next-to-next-to-leading order in perturbation theory. Particular emphasis is put on singularities associated to soft gluons. The knowledge of the singularity structure allows the construction of appropriate subtraction terms, which in turn

K. Lapidus

Inclusive production of e+e--pairs in pp and dp collisions at a kinetic beam energy of 1.25 GeV/u has been studied with the HADES spectrometer. In the latter case, the main goal was to obtain data on pair emission in quasi-free np collisions. To select this particular reaction channel the HADES experimental setup was extended with a Forward Wall hodoscope, w

Nobuhiro Yonezawa

We study free particles in a one-dimensional box with combinations of two types of boundary conditions: the Dirichlet condition and a one-parameter family of quasi-Neumann conditions at the two walls. We calculate energy spectra approximately and obtain equations of state having the same (one-dimensional) volume dependence as van der Waals equations of state

Andres Collinucci, Pablo Soler, Angel M. Uranga

We argue that the Gopakumar-Vafa interpretation of the topological string partition function can be used to compute and resum certain non-perturbative brane instanton effects of type II CY compactifications. In particular the topological string A-model encodes the non-perturbative corrections to the hypermultiplet moduli space metric from general D1/D(-1)-br

T. Gaitanos, M. Kaskulov, U. Mosel

The Lagrangian density of Relativistic Hadrodynamics (RHD) is extended by introducing non-linear derivative (NLD) interactions of the nucleon with the meson fields. As a consequence, the nucleon selfenergy becomes both momentum and density dependent. With a single cut-off parameter, which regulates the NLD Lagrangian, our approach is compatible with results

M. Pavon Valderrama, E. Ruiz Arriola

Within the framework of potential scattering theory we derive an analytical two-potential formula for the on-shell partial wave scattering amplitude. This formula embodies a large number of possible applications, including long range Coulomb forces as well as short distance singular potentials. As an example illustrating the use of the formula we analyze the

Andrei A. Fedorenko, David Carpentier

We propose a nonlinear sigma model for the description of quantum transport in a mesoscopic metallic conductor with magnetic impurities frozen in a spin glass phase. It accounts for the presence of both the corresponding scalar and magnetic random potentials. In a spin glass, this magnetic random potential is correlated between different realizations. As the

Dimitrios Manolopoulos, Ingo Runkel

Starting from an abelian rigid braided monoidal category C we define an abelian rigid monoidal category C_F which captures some aspects of perturbed conformal defects in two-dimensional conformal field theory. Namely, for V a rational vertex operator algebra we consider the charge-conjugation CFT constructed from V (the Cardy case). Then C = Rep(V) and an ob

Feng Qi, Bai-Ni Guo

In the paper, we extend Binet&#39;s first formula for the logarithm of the gamma function and investigate some properties, including inequalities, star-shaped and sub-additive properties and the complete monotonicity, of the extended remainder of Binet&#39;s first formula for the logarithm of the gamma function and related functions.

Luis P. Chimento, Ruth Lazkoz, Irene Sendra

We propose a model based on a DBI action for the unification of dark matter and dark energy. This is supported by the results of the study of its background behavior at early and late times, and reinforced by the analysis of the evolution of perturbations. We also perform a Bayesian analysis to set observational constraints on the parameters of the model usi

David Arthur, Bodo Manthey, Heiko Röglin

The k-means method is one of the most widely used clustering algorithms, drawing its popularity from its speed in practice. Recently, however, it was shown to have exponential worst-case running time. In order to close the gap between practical performance and theoretical analysis, the k-means method has been studied in the model of smoothed analysis. But ev

Andrea Loi, Roberto Mossa

Let $(M, g)$ be a real analytic Kaehler manifold. We say that a smooth map $E_p:W\to M$ from a neighborhood $W$ of the origin of $T_pM$ into $M$ is a {\em diastatic exponential} at $p$ if it satisfies $$(d \E_p)_0=\id_{T_pM},$$ $$D_p(\E_p (v))=g_p(v, v), \forall v\in W,$$ where $D_p$ is Calabi's diastasis function at $p$ (the usual exponential $\exp_p$ obvio

Fei Ren, Gao-Feng Gu, Wei-Xing Zhou

We perform return interval analysis of 1-min {\em{realized volatility}} defined by the sum of absolute high-frequency intraday returns for the Shanghai Stock Exchange Composite Index (SSEC) and 22 constituent stocks of SSEC. The scaling behavior and memory effect of the return intervals between successive realized volatilities above a certain threshold $q$ a

István Groma, Géza Györgyi, Péter Dusán Ispánovity

A variational approach is presented to calculate the stress field generated by a system of dislocations. It is shown that in the simplest case, when the material containing the dislocations obeys Hooke&#39;s law the variational framework gives the same field equations as Kröner&#39;s theory. However, the variational method proposed allows to study many other

Feng Qi, Bai-Ni Guo

For $m,n\in\mathbb{N}$, let $f_{m,n}(x)=\bigr[ψ^{(m)}(x)\bigl]^2+ψ^{(n)}(x)$ on $(0,\infty)$. In the present paper, we prove using two methods that, among all $f_{m,n}(x)$ for $m,n\in\mathbb{N}$, only $f_{1,2}(x)$ is nontrivially completely monotonic on $(0,\infty)$. Accurately, the functions $f_{1,2}(x)$ and $f_{m,2n-1}(x)$ are completely monotonic on $(0,\

Isao Kishimoto, Tomohiko Takahashi

We explore vacuum structure in bosonic open string field theory expanded around an identity based solution parameterized by $a$ (>= -1/2). Analyzing the expanded theory by using level truncation approximation up to level 14, we find that the theory has a stable vacuum solution for $a$>-1/2. The vacuum energy and the gauge invariant overlap numerically approa

Frédéric Bossens, Grégory Rayée, Nikos S. Skantzos, Griselda Deelstra

We study Vanna-Volga methods which are used to price first generation exotic options in the Foreign Exchange market. They are based on a rescaling of the correction to the Black-Scholes price through the so-called `probability of survival&#39; and the `expected first exit time&#39;. Since the methods rely heavily on the appropriate treatment of market data w

Feng Qi, Bai-Ni Guo

In the paper, necessary and sufficient conditions are presented for a function involving a ratio of gamma functions to be logarithmically completely monotonic. This extends and generalizes the main result in [\emph{Inequalities and monotonicity for the ratio of gamma functions}, Taiwanese J. Math. \textbf{7} (2003), no.~2, 239\nobreakdash--247.] and others.

CDF Collaboration, T. Aaltonen

We report a set of measurements of particle production in inelastic pbar{p} collisions collected with a minimum-bias trigger at the Tevatron Collider with the CDF II experiment. The inclusive charged particle transverse momentum differential cross section is measured, with improved precision, over a range about ten times wider than in previous measurements.

Martin Rubey, Christian Stump

In this article, we investigate bijections on various classes of set partitions of classical types that preserve openers and closers. On the one hand we present bijections that interchange crossings and nestings. For types B and C, they generalize a construction by Kasraoui and Zeng for type A, whereas for type D, we were only able to construct a bijection b

Italo J. Dejter

Like the Coxeter graph became reattached into the Klein graph in [2], the Levi graphs of the $9_3$ and $10_3$ self-dual configurations, known as the Pappus and Desargues ($k$-transitive) graphs $\mathcal P$ and $\mathcal D$ (where $k=3$), also admit reattachments of the distance-$(k-1)$ graphs of half of their oriented shortest cycles via orientation assignm

ZEUS Collaboration

The reduced cross sections for ep deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, 318, 251 and 225 GeV. From the cross sections, measured double differentially in Bjorken x and the virtuality, Q^2, the proton structure functions FL and F2 have been extracted in the region 5*10^-4 < x <0.

Wei Ming Zhang, Roberto Soria, Shuang Nan Zhang, Douglas A. Swartz

We have studied the X-ray nuclear activity of 187 nearby (distance < 15 Mpc) galaxies observed with Chandra/ACIS. We found that 86 of them have a point-like X-ray core, consistent with an accreting black hole (BH). We argue that the majority of them are nuclear BHs, rather than X-ray binaries. The fraction of galaxies with an X-ray detected nuclear BH is hig

Marcos Marino

We propose a new, precise integrality conjecture for the colored Kauffman polynomial of knots and links inspired by large N dualities and the structure of topological string theory on orientifolds. According to this conjecture, the natural knot invariant in an unoriented theory involves both the colored Kauffman polynomial and the colored HOMFLY polynomial f

Miao Li, Yi Pang, Yi Wang

We propose a model in which an energy-dependent time delay of a photon originates from space-time non-commutativity, the time delay is due to a noncommutative coupling between dilaton and photon. We predict that in our model, high energy photons with different momenta can either be delayed or superluminal, this may be related to a possible time delay reporte

Juan-Pablo Ortega

We apply a quadratic hedging scheme developed by Foellmer, Schweizer, and Sondermann to European contingent products whose underlying asset is modeled using a GARCH process and show that local risk-minimizing strategies with respect to the physical measure do exist, even though an associated minimal martingale measure is only available in the presence of bou

G. Cariolaro, G. Pierobon

In the literature the performance of quantum data transmission systems is usually evaluated in the absence of thermal noise. A more realistic approach taking into account the thermal noise is intrinsically more difficult because it requires dealing with Glauber coherent states in an infinite--dimensional space. In particular, the exact evaluation of the opti

Amna Ali, M. Sami, A. A. Sen

The string inspired tachyon field can serve as a candidate of dark energy. Its equation of state parameter $w$ varies from 0 to -1. In case of tachyon field potential $V(ϕ)\to 0$ slower(faster) than $1/ϕ^2$ at infinity, dark energy(dark matter) is a late time attractor. We investigate the tachyon dark energy models under the assumption that $w$ is close to -

Sanli Faez, P. M. Johnson, Ad Lagendijk

We introduce a new approach for measuring both the effective medium and the transport properties of light propagation in heterogeneous media. Our method utilizes the conceptual equivalence of frequency variation with a change in the effective index of refraction. Experimentally, we measure intensity correlations via spectrally resolved refractive index tunin

Tetsuichi Kishishita, Takaaki Tanaka, Yasunobu Uchiyama, Tadayuki Takahashi

We report on long-term stability of X-ray modulation apparently synchronized with an orbital period of 3.9 days in the gamma-ray binary LS 5039. Recent observations with the Suzaku satellite in the year 2007, which covered continuously more than one orbital period, have provided us with detailed characterization of X-ray flux and spectral shape as a function

Zhao Zhang, Teiji Kunihiro

We investigate the combined effect of the repulsive vector interaction and the positive electric chemical potential on the chiral phase transition by considering neutral color superconductivity (CSC). The chiral condensate, diquark condensate and quark number densities are solved in both two-flavor and two-plus-one-flavor Nambu-Jona-Lasinio(NJL) models with

Xiulian Wang, Mingzhe Li

The possible variation of the fine structure constant may be due to the non-minimal coupling of the electromagnetic field to a light scalar field which can be the candidate of dark energy. Its dynamical nature renders the fine structure constant varies with time as well as space. In this paper we point out the spatial fluctuation of the fine structure will m

K. Sengupta, Diptiman Sen

We compute concurrence and negativity as measures of two-site entanglement generated by a power-law quench (characterized by a rate 1/tau and an exponent alpha) which takes an anisotropic XY chain in a transverse field through a quantum critical point (QCP). We show that only the even-neighbor pairs of sites get entangled in such a process. Moreover, there i

Seung-Woo Lee, Hyunseok Jeong, Dieter Jaksch

We propose a scheme for witnessing entanglement in phase space by significantly inefficient detectors. The implementation of this scheme does not require any additional process for correcting errors in contrast to previous proposals. Moreover, it allows us to detect entanglement without full a priori knowledge of the detection efficiency. It is shown that en

Rohit Katti, Joseph Samuel, Supurna Sinha

The value of the cosmological constant is one of the major puzzles of modern cosmology: it is tiny but nonzero. Sorkin predicted, from the Causet approach to quantum gravity, that the cosmological constant has quantum fluctuations. The predicted order of magnitude of the fluctuations agrees with the subsequently observed value of the cosmological constant. W

Atul Dixit

We derive two new analogues of a transformation formula of Ramanujan involving the Gamma and Riemann zeta functions present in the Lost Notebook. Both involve infinite series consisting of Hurwitz zeta functions and yield modular relations. As a special case of the first formula, we obtain an identity involving polygamma functions given by Andrew P. Guinand