February 2008 arXiv papers — page 3

Nan Liang, Wei Ke Xiao, Yuan Liu, Shuang Nan Zhang

An important concern in the application of gamma-ray bursts (GRBs) to cosmology is that the calibration of GRB luminosity/energy relations depends on the cosmological model, due to the lack of a sufficient low-redshift GRB sample. In this paper, we present a new method to calibrate GRB relations in a cosmology-independent way. Since objects at the same redsh

Scott Funkhouser

The basic scaling laws for structures in a fractal universe require that the characteristic quantity of action associated with astronomical bodies should be of order near the maximum possible action allowed by the holographic upper bound. That conclusion is consistent with the observed parameters of galaxies and clusters.

Savas Dimopoulos, Peter W. Graham, Jason M. Hogan, Mark A. Kasevich

Atom interferometry is now reaching sufficient precision to motivate laboratory tests of general relativity. We begin by explaining the non-relativistic calculation of the phase shift in an atom interferometer and deriving its range of validity. From this we develop a method for calculating the phase shift in general relativity. This formalism is then used t

V. I. Kuksa, R. S. Pasechnik

Near-threshold production of neutral boson pairs is considered within the framework of the model of unstable particles with smeared mass. The results of calculations are in good agreement with LEP II data and Monte-Carlo simulations.

Renata Kallosh, Masoud Soroush

We present an explicit, exact to all orders in gravitational coupling E7(7) symmetry transformations of on-shell N=8 supergravity fields in the gauge with 70 scalars in E7(7)/SU(8) coset space, the local SU(8) symmetry being fixed. The non-linear realization of E7(7) includes a field-dependent SU(8) transformation preserving the unitary gauge. We find the co

Piotr Graczyk, Todd Kemp, Jean-Jacques Loeb, Tomasz Zak

We prove strong hypercontractivity (SHC) inequalities for logarithmically subharmonic functions on $\RR^n$ and different classes of measures: Gaussian measures on $\RR^n$, symmetric Bernoulli and symmetric uniform probability measures on $\RR$, as well as their convolutions. Surprisingly, a slightly weaker strong hypercontractivity property holds for {\em an

Eugen Paal

Reductivity in the Ma'tsev algebras is inquired. This property relates the Mal'tsev algebras to the general Lie triple systems.

D. W. Boukhvalov, M. I. Katsnelson

Opening, in a controllable way, the energy gap in the electronic spectrum of graphene is necessary for many potential applications, including an efficient carbon-based transistor. We have shown that this can be achieved by chemical functionalization of bilayer graphene. Using various dopants, such as H, F, Cl, Br, OH, CN, CCH, NH2, COOH, and CH3 one can vary

Ernesto F. Eiroa, Gustavo E. Romero

In this work we study gravitational lensing of neutrinos by Schwarzschild black holes. In particular, we analyze the case of a neutrino transient source associated with a gamma-ray burst lensed by a supermassive black hole located at the center of an interposed galaxy. We show that the primary and secondary images have an angular separation beyond the resolu

Jeffrey Stopple

A fast new algorithm is used compute the zeros of the quadratic character L-functions for all negative fundamental discriminants with absolute value 10^12<d<10^12+10^7. These are compared to the 1-level density, including various lower order terms. These terms come from, on the one hand the Explicit Formula, and on the other the L-functions Ratios Conjecture

M. Wetzstein, Andrew F. Nelson, T. Naab, A. Burkert

We present a Fortran 95 code for simulating the evolution of astrophysical systems using particles to represent the underlying fluid flow. The code is designed to be versatile, flexible and extensible, with modular options that can be selected either at compile time or at run time. We include a number of general purpose modules describing a variety of physic

Andrew F. Nelson, M. Wetzstein, T. Naab, .

We continue our presentation of VINE. We begin with a description of relevant architectural properties of the serial and shared memory parallel computers on which VINE is intended to run, and describe their influences on the design of the code itself. We continue with a detailed description of a number of optimizations made to the layout of the particle data

Jesus Romero, Mauricio Bellini

Using a recently introduced 5D Riemann flat metric, we investigate the possibility of introducing dissipation in the dynamics of the inflaton field on an effective 4D FRW metric, in the framework of the STM theory of gravity.

P. V. Buividovich, M. I. Polikarpov

The entropy of entanglement between a three-dimensional slab of thickness l and its complement is studied numerically for four-dimensional SU(2) lattice gauge theory. We find a signature of a nonanalytic behavior of the entanglement entropy, which was predicted recently for large N_c confining gauge theories in the framework of AdS/CFT correspondence. The de

Anita Eusebi, Stefano Mancini

We present an extension to a d-ary alphabet of a recently proposed deterministic quantum key distribution protocol. It relies on the use of mutually unbiased bases in prime power dimension d, for which we provide an explicit expression. Then, by considering a powerful individual attack, we show that the security of the protocol is maximal for d=3.

Peter Stano, Daniel Reitzner, Teiko Heinosaari

We characterize all coexistent pairs of qubit effects. This gives an exhaustive description of all pairs of events allowed, in principle, to occur in a single qubit measurement. The characterization consists of three disjoint conditions which are easy to check for a given pair of effects. Known special cases are shown to follow from our general characterizat

M. Segond, L. Szymanowski, S. Wallon

We consider the exclusive production of rho^0 meson pairs in gamma^*gamma^* scattering in the Regge limit of QCD as a probe of BFKL resummation effects and we show the feasibility of the measurement of this process at the ILC.

N. A. Carella

This note continues the theoretical development of deterministic integer factorization algorithms based on systems of polynomials equations. The main result establishes a new deterministic time complexity bench mark in integer factorization.

Radouane Gannouji, David Polarski

We consider asymptotically stable scalar-tensor dark energy (DE) models for which the equation of state parameter $w_{DE}$ tends to zero in the past. The viable models are of the phantom type today, however this phantomness is milder than in General Relativity if we take into account the varying gravitational constant when dealing with the SNIa data. We stud

Nikolaos Kidonakis, Agustin Sabio Vera, Philip Stephens

We discuss different resummations of large logarithms that arise in hard-scattering cross sections of quarks and gluons in regions of large and small x. The large-x logarithms are typically dominant near threshold for the production of a specified final state. These soft and collinear gluon corrections produce large enhancements of the cross section for many

P. Aniello, V. I. Man&#39;ko, G. Marmo

Using the notions of frame transform and of square integrable projective representation of a locally compact group $G$, we introduce a class of isometries (tight frame transforms) from the space of Hilbert-Schmidt operators in the carrier Hilbert space of the representation into the space of square integrable functions on the direct product group $G\times G$

R. Roth, S. Reinhardt, H. Hergert

We discuss relations and differences between two methods for the construction of unitarily transformed effective interactions, the Similarity Renormalization Group (SRG) and Unitary Correlation Operator Method (UCOM). The aim of both methods is to construct a soft phase-shift equivalent effective interaction which is well suited for many-body calculations in

L. Sbano, M. Kirkilionis

The paper analyses stochastic systems describing reacting molecular systems with a combination of two types of state spaces, a finite-dimensional, and an infinite dimenional part. As a typical situation consider the interaction of larger macro-molecules, finite and small in numbers per cell (like protein complexes), with smaller, very abundant molecules, for

Ranko Lazic

A data word is a sequence of pairs of a letter from a finite alphabet and an element from an infinite set, where the latter can only be compared for equality. Safety one-way alternating automata with one register on infinite data words are considered, their nonemptiness is shown EXPSPACE-complete, and their inclusion decidable but not primitive recursive. Th

Carl H. Albright, Mu-Chun Chen

There have been many theoretical models constructed which aim to explain the neutrino masses and mixing patterns. While many of the models will be eliminated once more accurate determinations of the mixing parameters, especially $\sin^2 2θ_{13}$, are obtained, charged lepton flavor violation (LFV) experiments are able to differentiate even further among the

S. J. Williams, D. R. Gies, T. J. Henry, J. A. Orosz

We present results from an optical spectroscopic investigation of the massive binary system [L72] LH~54-425 in the LH 54 OB association in the Large Magellanic Cloud. We revise the ephemeris of [L72] LH 54-425 and find an orbital period of 2.247409 +/- 0.000010 days. We find spectral types of O3 V for the primary and O5 V for the secondary. We made a combine

O. A. Castro-Alvaredo, B. Doyon

In this paper we generalise the main result of a recent work by J. L. Cardy and the present authors concerning the bi-partite entanglement entropy between a connected region and its complement. There the expression of the leading order correction to saturation in the large distance regime was obtained for integrable quantum field theories possessing diagonal

Kamal L. Panigrahi, Harvendra Singh

We study the assisted inflation scenario from the rolling of $N$ BPS D3-brane into the NS5-branes, on a transverse geometry of $R^3 \times S^1$, coupled to four dimensional gravity. We assume that the branes are distributed along $S^1$ and the probe D3-branes spin along $R^3$ plane. Qualitatively this process is similar to that of N-tachyon assisted inflatio

Josef Juran, Peter Lichard

The e+e- --> pi+pi-pi0pi0 reaction cross section as a function of the incident energy is calculated using a model that is an extension of our recently published model of the e+e- annihilation into four charged pions. The latter considered the intermediate states with the pi, rho, and a_1 mesons and fixed the mixing angle of the a_1-rho-pi Lagrangian and othe

R. P. Malik

We discuss various symmetry properties of the Lagrangian density of a four (3 + 1)-dimensional (4D) free Abelian 2-form gauge theory within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism. The present free Abelian gauge theory is endowed with a Curci-Ferrari type condition which happens to be a key signature of the 4D non-Abelian 1-form gauge the

Gabriel H. Tucci

Let $\{T_{k}\}_{k=1}^{\infty}$ be a family of *--free identically distributed operators in a finite von Neumann algebra. In this work we prove a multiplicative version of the free central limit Theorem. More precisely, let $B_{n}=T_{1}^{*}T_{2}^{*}... T_{n}^{*}T_{n}... T_{2}T_{1}$ then $B_{n}$ is a positive operator and $B_{n}^{1/2n}$ converges in distributi

Martin Horvat, Mirko Degli Esposti, Stefano Isola, Tomaz Prosen

In this paper we study in detail, both analytically and numerically, the dynamical properties of the triangle map, a piecewise parabolic automorphism of the two-dimensional torus, for different values of the two independent parameters defining the map. The dynamics is studied numerically by means of two different symbolic encoding schemes, both relying on th

Simone De Liberato, Cristiano Ciuti

Through a non-perturbative quantum theory, we investigate how the quasi-electron excitations of a two-dimensional electron gas are modified by strong coupling to the vacuum field of a microcavity. We show that the electronic dressed states originate from a Fano-like coupling between the bare electron states and the continuum of intersubband cavity polariton

CLEO Collaboration, R. E. Mitchell

Using a 281 pb^-1 data sample collected at the psi(3770) resonance with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of D^+ to eta e^+ nu_e. We also set upper limits for D^+ to eta&#39; e^+ nu_e and D^+ to phi e^+ nu_e that are about two orders of magnitude more restrictive than those obtained by previous experime

Lucia Di Vizio

In this paper, we establish, under convenient diophantine assumptions, a complete analytic classification of $q$-difference modules over the field of germs of meromorphic functions at zero, proving some analytic analogs of the results by Soibelman and Vologodsky, cf. math.AG/0205117, and by Baranovsky and Ginzburg, cf. alg-geom/9607008.

CLEO Collaboration, G. Bonvicini

We perform a Dalitz plot analysis of D^+ -> K^-pi^+pi^+ decay with the CLEO-c data set of 572 pb^-1 of e^+e^- collisions accumulated at the psi(3770). This corresponds to 1.6 million D^+D^- pairs from which we select 140793 candidate events with a small background of 1.1%. We compare our results with previous measurements using the isobar model. We modify th

C. P. Burgess, Claudia de Rham, Leo van Nierop

We examine brane-world scenarios in which all the observed Standard Model particles reside on a brane but the Higgs is an elementary extra-dimensional scalar in the bulk. We show that, for codimension 2 branes, often-neglected interactions between the bulk Higgs and the branes cause two novel effects. First, they cause <H> to depend only logarithmically on t

Jean J. Heremans, Djordje Minic

Electromagnetic duality between the Aharonov-Bohm and the Aharonov-Casher quantum mechanical phases predicts the existence of a new collective state of matter which can be regarded as a spin dual to the fractional quantum Hall effect. The state, induced by electric fields, is driven by effective spin-spin interactions. We derive experimental and materials co

Jerzy Szwed

Interference effects are the most spectacular manifestation of the wave nature of phenomena. This note proposes a systematic search for such effects in the brain.

G. Battaglia, A. Helmi, E. Tolstoy, M. Irwin

We present VLT/FLAMES spectroscopic observations (R~6500) in the CaII triplet region for 470 probable kinematic members of the Sculptor (Scl) dwarf spheroidal galaxy. The accurate velocities (+- 2 km/s) and large area coverage of Scl allow us to measure a velocity gradient of 7.6_{-2.2}^{+3.0} km/s deg^{-1} along the Scl projected major axis, likely a signat

S. Ciuchi, S. Fratini

We apply dynamical mean field theory to study a prototypical model that describes charge ordering in the presence of both electron-lattice interactions and intersite electrostatic repulsion between electrons. We calculate the optical and d.c. conductivity, and derive approximate formulas valid in the limiting electron-lattice coupling regimes. In the weak co

Haitan Xu, Xin Wan

We discuss how to significantly reduce leakage errors in topological quantum computation by introducing an irrelevant error in phase, using the construction of a CNOT gate in the Fibonacci anyon model as a concrete example. To be specific, we construct a functional braid in a six-anyon Hilbert space that exchanges two neighboring anyons while conserving the

Fabio Finelli, Matteo Galaverni

We discuss the rotation of the linear polarization plane and the production of circular polarization generated by a pseudoscalar field acting as dark matter. We compute analytically and numerically the propagation of the Stokes parameters from the last scattering surface for an oscillating and a monotonic decreasing pseudoscalar field. For the models studied

Alvaro Duenas-Vidal, Miguel A. Vazquez-Mozo

We study noncommutative deformations of Yang-Mills theories and show that these theories admit a infinite, continuous family of twisted star-gauge invariances. This family interpolates continuously between star-gauge and twisted gauge transformations. The possible physical role of these start-twisted invariances is discussed.

P. Kotetes, G. Varelogiannis

We demonstrate that the formation of a chiral d-density wave (CDDW) state generates a Topological Meissner effect (TME) in the absence of any kind of superconductivity. The TME is identical to the usual superconducting Meissner effect but it appears only for magnetic fields perpendicular to the plane while it is absent for in plane fields. The observed enhan

Mark Berman

We study the local zeta functions of an algebraic group $\mathcal{G}$ defined over $\mathfrak{K}$ together with a faithful $\mathfrak{K}$-rational representation $ρ$ for a finite extension $\mathfrak{K}$ of $\mathbb{Q}$. These are given by integrals over $\mathfrak{p}$-adic points of $\mathcal{G}$ determined by $ρ$ for a prime $\mathfrak{p}$ of $\mathfrak{K}

Lan Zhou, Z. R. Gong, Yu-xi Liu, C. P. Sun

We analyze coherent transport of photons, which propagate in a one-dimensional coupled-resonator waveguide (CRW) and are scattered by a controllable two-level system located inside the CRW. Our approach, which uses discrete coordinates, unifies &#34;low&#34; and &#34;high&#34; energy effective theories for single photon scattering. We show that the controlla

Semyon Alesker, Misha Verbitsky

A quaternionic version of the Calabi problem on Monge-Ampere equation is introduced. It is a quaternionic Monge-Ampere equation on a compact hypercomplex manifold with an HKT-metric. The equation is non-linear elliptic of second order. For a hypercomplex manifold with holonomy in SL(n;H), uniqueness (up to a constant) of a solution is proven, as well as the

T. Schulte-Herbrueggen, S. J. Glaser, G. Dirr, U. Helmke

For addressing optimisation tasks on finite dimensional quantum systems, we give a comprehensive account of the foundations of gradient flows on Riemannian manifolds including new developments: we extend former results from Lie groups such as the full unitary group to closed subgroups like partitionings by factorisation into tensor products, where the finest

Joel Ratsaby

Instead of static entropy we assert that the Kolmogorov complexity of a static structure such as a solid is the proper measure of disorder (or chaoticity). A static structure in a surrounding perfectly-random universe acts as an interfering entity which introduces local disruption in randomness. This is modeled by a selection rule $R$ which selects a subsequ

Itaï Ben Yaacov

We prove that in a continuous $\aleph_0$-stable theory every type-definable group is definable. The two main ingredients in the proof are: \begin{enumerate} \item Results concerning Morley ranks (i.e., Cantor-Bendixson ranks) from \cite{BenYaacov:TopometricSpacesAndPerturbations}, allowing us to prove the theorem in case the metric is invariant under the gro

Florent Autin, Erwan Le Pennec, Jean-Michel Loubes, Vincent Rivoirard

We address the statistical issue of determining the maximal spaces (maxisets) where model selection procedures attain a given rate of convergence. By considering first general dictionaries, then orthonormal bases, we characterize these maxisets in terms of approximation spaces. These results are illustrated by classical choices of wavelet model collections.

B. Georges, J. Grollier, M. Darques, V. Cros

The phase locking behavior of spin transfer nano-oscillators (STNOs) to an external microwave signal is experimentally studied as a function of the STNO intrinsic parameters. We extract the coupling strength from our data using the derived phase dynamics of a forced STNO. The predicted trends on the coupling strength for phase locking as a function of intrin

Itaï Ben Yaacov

We settle several questions regarding the model theory of Nakano spaces left open by the PhD thesis of Pedro Poitevin \cite{Poitevin:PhD}. We start by studying isometric Banach lattice embeddings of Nakano spaces, showing that in dimension two and above such embeddings have a particularly simple and rigid form. We use this to show show that in the Banach lat

Ignacio de Gregorio, David Mond, Christian Sevenheck

We study linear functions on fibrations whose central fibre is a linear free divisor. We analyse the Gauss-Manin system associated to these functions, and prove the existence of a primitive and homogenous form. As a consequence, we show that the base space of the semi-universal unfolding of such a function carries a Frobenius manifold structure.

Tobias Jaeger

A conservative irrational pseudo-rotation of the two-torus is semi-conjugate to the irrational rotation if and only if it has the property of bounded mean motion [10]. (Here 'irrational pseudo-rotation' means a toral homeomorphism with uniquely defined, totally irrational rotation vector.) The aim of this note is to explore this concept some further. For ins

Adi Armoni, Timothy J. Hollowood

We consider large-N confining gauge theories with a Hagedorn density of states. In such theories the potential between a pair of colour-singlet sources may diverge at a critical distance r_c = 1/ T_H. We consider, in particular, pure N=1 super Yang-Mills theory and argue that when a domain-wall and an anti domain-wall are brought to a distance near r_c the i

M. Moretti, F. Piccinini, A. D. Polosa

We suggest a new approach for the automatic and fully numerical evaluation of one-loop scattering amplitudes in perturbative quantum field theory. We use suitably formulated dispersion relations to perform the calculation as a convolution of tree-level amplitudes. This allows to take advantage of the iterative numerical algorithms for the evaluation of leadi

Paul Busch, Heinz-Jürgen Schmidt

Two quantum events, represented by positive operators (effects), are coexistent if they can occur as possible outcomes in a single measurement scheme. Equivalently, the corresponding effects are coexistent if and only if they are contained in the ranges of a single (joint) observable. Here we give several equivalent characterizations of coexistent pairs of q

P. Roy Chowdhury, C. Samanta, D. N. Basu

Theoretical estimates for the half lives of about 1700 isotopes of heavy elements with Z from 100 to 130 are tabulated using theoretical Q-values. The quantum mechanical tunneling probabilities are calculated within a WKB framework using microscopic nuclear potentials. The microscopic nucleus-nucleus potentials are obtained by folding the densities of intera

N. R. Thompson, B. W. J. McNeil

A technique is proposed to generate attosecond pulse trains of radiation from a Free-Electron Laser amplifier. The optics-free technique synthesises a comb of longitudinal modes by applying a series of spatio-temporal shifts between the co-propagating radiation and electron bunch in the FEL. The modes may be phase-locked by modulating the electron beam energ

Valerio Scarani, Helle Bechmann-Pasquinucci, Nicolas J. Cerf, Miloslav Dusek

Quantum key distribution (QKD) is the first quantum information task to reach the level of mature technology, already fit for commercialization. It aims at the creation of a secret key between authorized partners connected by a quantum channel and a classical authenticated channel. The security of the key can in principle be guaranteed without putting any re

Hao Wei

Recently, some efforts focus on differentiating dark energy and modified gravity with the growth function $δ(z)$. In the literature, it is useful to parameterize the growth rate $f\equiv d\lnδ/d\ln a=Ω_m^γ$ with the growth index $γ$. In this note, we consider the general DGP model with any $Ω_k$. We confront the growth index of DGP model with currently avail

Mihoko M. Nojiri, Michihisa Takeuchi

In the Littlest Higgs model with T-parity (LHT), top-partners (T_-) are produced in pairs at the Large Hadron Collider (LHC). Each top-partner decays into a top quark (t) and the lightest T-odd gauge partner A_H. We demonstrate reconstruction of the ttbar system decaying hadronically, and measurement of the top-partner mass from the m_{T2} distribution. A to

Tetsuo Hatsuda, Motoi Tachibana, Naoki Yamamoto

The vector mesons in three-flavor quark matter with chiral and diquark condensates are studied using the in-medium QCD sum rules. The diquark condensate leads to a mass splitting between the flavor-octet and flavor-singlet channels. At high density, the singlet vector meson disappears from the low-energy spectrum, while the octet vector mesons survive as lig

Takuji Arai

We shall provide in this paper good deal pricing bounds for contingent claims induced by the shortfall risk with some loss function. Assumptions we impose on loss functions and contingent claims are very mild. We prove that the upper and lower bounds of good deal pricing bounds are expressed by convex risk measures on Orlicz hearts. In addition, we obtain it

Keisuke Fujii, Katsuji Yamamoto

A novel scheme is presented for fault-tolerant quantum computation based on the cluster model. Some relevant logical cluster states are constructed in concatenation by post-selection through verification, without necessity of recovery operation, where a suitable code such as the Steane&#39;s 7-qubit code is adopted for transversal operations. This simple con

Kazuhide Ichikawa, Teruaki Suyama, Tomo Takahashi, Masahide Yamaguchi

We study non-Gaussianity, the spectral index of primordial scalar fluctuations and tensor modes in models where fluctuations from the inflaton and the curvaton can both contribute to the present cosmic density fluctuations. Even though simple single-field inflation models generate only tiny non-Gaussianity, if we consider such a mixed scenario, large non-Gau

Guo Lei, Ma Wen-Gan, Zhang Ren-You, Wang Shao-Ming

We study the full contributions at the leading order(LO) and QCD next-to-leading order(NLO) to the cross section of the \eewwbb process in the standard model(SM) at the ILC. In dealing the resonance problem we adopted the complex mass scheme in both tree-level and one-loop level perturbative calculations. Our numerical results show that the K-factor varies f

Russell K. Standish

Anthropic reasoning is a form of statistical reasoning based upon finding oneself a member of a particular reference class of conscious beings. By considering empirical distribution functions defined over animal life on Earth, we can deduce that the vast bulk of animal life is unlikely to be conscious.

Guo-meng Zhao, Pieder Beeli

We report magnetic measurements up to 1200 K on multi-walled carbon nanotube mats using Quantum Design vibrating sample magnetometer. Extensive magnetic data consistently show two ferrromagnetic-like transitions at about 1000 K and 1275 K, respectively. The lower transition at about 1000 K is associated with an Fe impurity phase and its saturation magnetizat

N. Brodskiy, J. Dydak, B. Labuz, A. Mitra

In Rips Complexes and Covers in the Uniform Category (arXiv:0706.3937) we define, following James, covering maps of uniform spaces and introduce the concept of generalized uniform covering maps. In this paper we investigate when these covering maps are induced by group actions. Also, as an application of our results we present an exposition of Prajs&#39; hom

G. K. Leontaris

A three-family non-supersymmetric model with U(3)^3 gauge symmetry is analyzed in the context of intersecting D-branes. This is equivalent to the `trinification&#39; model extended by three U(1) factors which survive as global symmetries in the low energy effective model. The Standard Model fermions are accommodated in the three possible bifundamental multip

Anton Alekseev, Charles Torossian

The Kashiwara-Vergne (KV) conjecture is a property of the Campbell-Hausdorff series put forward in 1978. It has been settled in the positive by E. Meinrenken and the first author in 2006. In this paper, we study the uniqueness issue for the KV problem. To this end, we introduce a family of infinite dimensional groups KV_n, and an extension \hat{KV}_2 of the

Man-On Pun, Visa Koivunen, H. Vincent Poor

Opportunistic scheduling (OS) schemes have been proposed previously by the authors for multiuser MIMO-SDMA downlink systems with linear combining. In particular, it has been demonstrated that significant performance improvement can be achieved by incorporating low-complexity linear combining techniques into the design of OS schemes for MIMO-SDMA. However, th

J. H. Croston, M. J. Hardcastle, M. Birkinshaw, D. M. Worrall

We present a detailed study of the environments of a sample of nine low-power radio galaxies, based on new and archival XMM-Newton observations. We report new detections of group-scale environments around three radio galaxies, 3C 296, NGC 1044 and 3C 76.1. As with previous studies, we find that FR-I radio galaxies inhabit group environments ranging over near

R. A. Garcia, A. Jimenez, S. Mathur, J. Ballot

Since the beginning of this century we have attended a blooming of the gravity-mode research thanks to the unprecedented quality of the data available, either from space with SoHO, or from the ground-based networks as BiSON or GONG. From the first upper limit of the gravity-mode amplitudes fixed at 10 mm/s at 200 microHz given by Appourchaux et al. (2000), o

Man-On Pun, Kyeong Jin Kim, H. Vincent Poor

Opportunistic scheduling and beamforming schemes with reduced feedback are proposed for MIMO-OFDMA downlink systems. Unlike the conventional beamforming schemes in which beamforming is implemented solely by the base station (BS) in a per-subcarrier fashion, the proposed schemes take advantages of a novel channel decomposition technique to perform beamforming

Hsin-Chia Cheng, Dalit Engelhardt, John F. Gunion, Zhenyu Han

Many beyond the Standard Model theories include a stable dark matter candidate that yields missing / invisible energy in collider detectors. If observed at the Large Hadron Collider, we must determine if its mass and other properties (and those of its partners) predict the correct dark matter relic density. We give a new procedure for determining its mass wi

Man-On Pun, Weiyan Ge, Dong Zheng, Junshan Zhang

Distributed opportunistic scheduling (DOS) protocols are proposed for multiple-input multiple-output (MIMO) ad-hoc networks with contention-based medium access. The proposed scheduling protocols distinguish themselves from other existing works by their explicit design for system throughput improvement through exploiting spatial multiplexing and diversity in

Dong Zheng, Man-On Pun, Weiyan Ge, Junshan Zhang

Distributed opportunistic scheduling is studied for wireless ad-hoc networks, where many links contend for one channel using random access. In such networks, distributed opportunistic scheduling (DOS) involves a process of joint channel probing and distributed scheduling. It has been shown that under perfect channel estimation, the optimal DOS for maximizing

Qiudong Wang

In this paper we use the second order equation $\frac{d^2 q}{dt^2} + (λ- γq^2) \frac{d q}{dt} - q + q^3 = μq^2 \sin ωt$ as a demonstrative example to illustrate how to apply the analysis of \cite{WO} and \cite{WOk} to the studies of concrete equations. We prove, among many other things, that there are positive measure sets of parameters $(λ, γ, μ, ω)$ corres

J. M. Landsberg

These are expository notes from the 2008 Srni Winter School. They have two purposes: (1) to give a quick introduction to exterior differential systems (EDS), which is a collection of techniques for determining local existence to systems of partial differential equations, and (2) to give an exposition of recent work (joint with C. Robles) on the study of the

L. Sbano, M. Kirkilionis

In this paper we consider deterministic limits of molecular stochastic systems with finite and infinite degrees of freedom. The method to obtain the deterministic vector field is based on the continuum limit of such microscopic systems which has been derived in [11]. With the aid of the theory we finally develop a new approach for molecular systems that desc

Sibylle Braungardt, Aditi Sen De, Ujjwal Sen, Roy J. Glauber

We apply the atom counting theory to strongly correlated Fermi systems and spin models, which can be realized with ultracold atoms. The counting distributions are typically sub-Poissonian and remain smooth at quantum phase transitions, but their moments exhibit critical behavior, and characterize quantum statistical properties of the system. Moreover, more d

N. G. Parker, A. M. Martin, C. S. Adams, S. L. Cornish

Motivated by recent experimental observations, we study theoretically multiple bright solitary waves of trapped Bose-Einstein condensates. Through variational and numerical analyses, we determine the threshold for collapse of these states. Under $\pi$-phase differences between adjacent waves, we show that the experimental states lie consistently at the thres

Martin Bojowald, Reza Tavakol

Despite its great successes in accounting for the current observations, the so called `standard&#39; model of cosmology faces a number of fundamental unresolved questions. Paramount among these are those relating to the nature of the origin of the universe and its early evolution. Regarding the question of origin, the main difficulty has been the fact that w

R. Jaramillo, Yejun Feng, J. C. Lang, Z. Islam

The spin- and charge-density-wave order parameters of the itinerant antiferromagnet chromium are measured directly with non-resonant x-ray diffraction as the system is driven towards its quantum critical point with high pressure using a diamond anvil cell. The exponential decrease of the spin and charge diffraction intensities with pressure confirms the harm

S. P. Koduvayur, L. P. Rokhinson, D. C. Tsui, L. N. Pfeiffer

We investigate effects of lateral confinement on spin splitting of energy levels in 2D hole gases grown on [311] GaAs. We found that lateral confinement enhances anisotropy of spin splitting relative to the 2D gas for both confining directions. Unexpectedly, the effective $g$-factor does not depend on the 1D energy level number $N$ for $B\|[0\bar{1}1]$ while

Salah A. Aly

We demonstrate propagation rules of subsystem code constructions by extending, shortening and combining given subsystem codes. Given an $[[n,k,r,d]]_q$ subsystem code, we drive new subsystem codes with parameters $[[n+1,k,r,\geq d]]_q$, $[[n-1,k+1,r,\geq d-1]]_q$, $[[n,k-1,r+1,d]]_q$. The interested readers shall consult our companion papers for upper and lo

S. Kuzhel

The concept of $\mathcal{C}$-symmetries for pseudo-Hermitian Hamiltonians is studied in the Krein space framework. A generalization of $\mathcal{C}$-symmetries is suggested.

Shwetank Kumar, Jiansong Gao, Jonas Zmuidzinas, Benjamin A. Mazin

We present measurements of the temperature and power dependence of the resonance frequency and frequency noise of superconducting niobium thin-film coplanar waveguide resonators, carried out at temperatures well below the superconducting transition (T_{c}=9.2 K). The noise decreases by nearly two orders of magnitude as the temperature is increased from 120 t

J. Dorignac, A. Gaidarzhy, P. Mohanty

We develop a simple continuum model to analyze the vibrational modes of a nanomechanical multi-element structure. In this model, arrays of sub-micron cantilevers located symmetrically on both sides of the central clamped-clamped nanobeam are replaced by a continuum. In this approach, the punctual shear forces exerted by the cantilevers on the central beam ar

I. Mukha, L. Grigorenko, K. Summerer, L. Acosta

Proton-proton correlations were observed for the two-proton decays of the ground states of $^{19}$Mg and $^{16}$Ne. The trajectories of the respective decay products, $^{17}$Ne+p+p and $^{14}$O+p+p, were measured by using a tracking technique with microstrip detectors. These data were used to reconstruct the angular correlations of fragments projected on pla

D0 Collaboration, V. Abazov

A fully reconstructed Bc --> Jpsi Pi signal is observed with the D0 detector at the Fermilab Tevatron p-pbar collider. Using 1.3 inverse femtobarns of integrated luminosity, the signal is extracted with a significance more than five standard deviations above background. The measured Bc meson mass is 6300 (+-) 14 (stat) (+-) 5 (sys) MeV/cc

Jerzy Matyjasek

It is shown that for the spherically-symmetric and static systems the hypotheses posed by Yang and Radinschi and by Vagenas can be related to the particular distribution of the source. Simple proofs are given and a number of examples are discussed with the special emphasis put on the quantum corrected Schwarzschild black hole.

E. S. Kyoseva, N. V. Vitanov

We show that the solution of a multistate system composed of N degenerate lower (ground) states and one upper (excited) state can be reduced by using the Morris-Shore transformation to the solution of a two-state system involving only the excited state and a (bright) superposition of ground states. In addition, there are N-1 dark states composed of ground st

Andreas Henrici, Thomas Kappeler

In this paper we prove that the periodic Toda lattice admits globally defined Birkhoff coordinates.

S. Sassine, Yu. Krupko, J. -C. Portal, Z. D. Kvon

We report on experimental evidence of directed electron transport, induced by external linear-polarized microwave irradiation, in a two-dimensional spatially-periodic asymmetrical system called ratchet. The broken spatial symmetry was introduced in a high mobility two-dimensional electron gas based on AlGaAs/GaAs heterojunction, by patterning an array of art

E. S. Kyoseva, N. V. Vitanov, B. W. Shore

Manipulation of superpositions of discrete quantum states has a mathematical counterpart in the motion of a unit-length statevector in an N-dimensional Hilbert space. Any such statevector motion can be regarded as a succession of two-dimensional rotations. But the desired statevector change can also be treated as a succession of reflections, the generalizati