September 2007 arXiv papers — page 35

Emil Avsar, Gosta Gustafson, Leif Lonnblad

We have in earlier papers presented an extension of Mueller's dipole cascade model, which includes subleading effects from energy conservation and running coupling as well as colour suppressed effects from pomeron loops via a ``dipole swing''. The model was applied to describe the total cross sections in pp and gamma*p collisions. In this paper w

Jean-Philippe Lenain

The High Energy Stereoscopic System (H.E.S.S.) experiment, a ground-based gamma-ray Cherenkov telescope array located in Namibia, has now detected many extragalactic objects, which redshifts range from z=0.00183 up to z=0.2, possibly more. With the increasing performances of Cherenkov telescopes, it now becomes possible to probe these objects at small timesc

León Berdichevsky, Pieter Naaijkens

We calculate four-point correlation functions of two weight-2 and two weight-3 1/2-BPS operators in \mathcal{N}=4 SYM in the large N limit in supergravity approximation. By the AdS/CFT conjecture, these operators are dual to AdS supergravity scalar fields s_2 and s_3 with mass m^2 = -4 and m^2 = -3 respectively. This is the first non-trivial four-point funct

Kavita Jain, Freddy Bouchet, David Mukamel

We consider several models with long-range interactions evolving via Hamiltonian dynamics. The microcanonical dynamics of the basic Hamiltonian Mean Field (HMF) model and perturbed HMF models with either global anisotropy or an on-site potential are studied both analytically and numerically. We find that in the magnetic phase, the initial zero magnetization

U. Kuhl, F. M. Izrailev, A. A. Krokhin

We experimentally study the effect of enhancement of localization in weak one-dimensional random potentials. Our experimental setup is a single mode waveguide with 100 tuneable scatterers periodically inserted into the waveguide. By measuring the amplitudes of transmitted and reflected waves in the spacing between each pair of scatterers, we observe a strong

V. K. Oikonomou

The temperature inversion symmetry $R\to \frac{1}{T}$ is studied for the finite temperature effective potential of the N=1, $d=5$, supersymmetric $SU(3)_{c}{\times}SU(3)_{w}$ model, on the orbifold $S^{1}/Z_{2}$. For the value of the Wilson line parameter $α=1$ ($SU(2)_{L}$ breaks to a $U'(1)$), it is found that the effective potential contains a symmetr

G. P. Guo, Y. J. Zhao, T. Tu, X. J. Hao

In condensed matter physics, the study of electronic states with SU(N) symmetry has attracted considerable and growing attention in recent years, as systems with such a symmetry can often have a spontaneous symmetry-breaking effect giving rise to a novel ground state. For example, pseudospin quantum Hall ferromagnet of broken SU(2) symmetry has been realized

T. Suehara, H. Yoda, M. Oroku, T. Yamanaka

Shintake monitor is a nanometer-scale electron beam size monitor. It probes a electron beam by an interference fringe pattern formed by split laser beams. Minimum measurable beam size by this method is less than 1/10 of laser wavelength. In ATF2, Shintake monitor will be used for the IP beam size monitor to measure 37 nm (design) beam size. Development statu

Belle Collaboration, L. Widhalm

We present a measurement of the branching fraction $B(D_s^+\toμ^+ν_μ)$ using a 548 fb$^{-1}$ data sample collected by the Belle experiment at the KEKB $e^+e^-$ collider. The $D_s$ momentum is determined by reconstruction of the system recoiling against $DKγX$ in events of the type $e^+e^-\to D_s^\ast DKX, D_s^\ast \to D_sγ$, where $X$ represents additional p

M. Afzelius, M. U. Staudt, H. de. Riedmatten, C. Simon

We report an interference experiment of spontaneous emission of light from two distant solid-state ensembles of atoms that are coherently excited by a short laser pulse. The ensembles are Erbium ions doped into two LiNbO3 crystals with channel waveguides, which are placed in the two arms of a Mach-Zehnder interferometer. The light that is spontaneously emitt

G. Pacelli Bessa, J. Fabio Montenegro

Based on Markvorsen and Palmer's work on mean time exit and isoperimetric inequalities we establish slightly better isoperimetric inequalities and mean time exit estimates for minimal submanifolds of $N\times\mathbb{R}$. We also prove isoperimetric inequalities for submanifolds of Hadamard spaces with tamed second fundamental form.

C. Sevik, C. Bulutay

For Si and Ge nanocrystals (NCs) embedded in wide band-gap matrices, Auger recombination (AR) and carrier multiplication (CM) lifetimes are computed exactly in a three-dimensional real space grid using empirical pseudopotential wave functions. Our results in support of recent experimental data offer new predictions. We extract simple Auger constants valid fo

P. Plochocka, C. Faugeras, M. Orlita, M. L. Sadowski

We have investigated the absorption spectrum of multilayer graphene in high magnetic fields. The low energy part of the spectrum of electrons in graphene is well described by the relativistic Dirac equation with a linear dispersion relation. However, at higher energies (>500 meV) a deviation from the ideal behavior of Dirac particles is observed. At an energ

Andrew Sunderland, Li Ju, Wayne McRae, David G. Blair

In this paper we report a detailed investigation of a number of different materials commonly used in precision instrumentation in the view of using them as critical components in the magnetic gradiometer. The materials requirement inside a magnetic gradiometer is stringent because the presence of magnetic susceptible material will introduce intrinsic errors

Peter Lajko, Loic Turban, Ferenc Igloi

We consider two critical semi-infinite subsystems with different critical exponents and couple them through their surfaces. The critical behavior at the interface, influenced by the critical fluctuations of the two subsystems, can be quite rich. In order to examine the various possibilities, we study a system composed of two coupled Ashkin-Teller models with

T. V. Fityo, I. O. Vakarchuk, V. M. Tkachuk

A Bohr-Sommerfeld quantization rule is generalized for the case of the deformed commutation relation leading to minimal uncertainties in both coordinate and momentum operators. The correctness of the rule is verified by comparing obtained results with exact expressions for corresponding spectra.

Jimmy A. Hutasoit, Niko Jokela

Rolling tachyon backgrounds, arising from open strings on unstable branes in bosonic string theory, can be related to a simple statistical mechanical model - Coulomb gas of point charges in two dimensions confined to a circle, the Dyson gas. In this letter we describe a statistical system that is dual to non-BPS branes in superstring theory. We argue that ev

Niko Jokela, Esko Keski-Vakkuri, Jaydeep Majumder

It has long been known that there is a relation between boundary sine-Gordon theory and thermodynamics of charge neutral two-component Coulomb plasma on a unit circle. On the other hand, recently it was found that open string worldsheet description of brane decay can be related to a sequence of points of thermodynamic equilibrium of one-component plasma. Her

Dongsheng Du

We firstly address the recent efforts on calculations of the next-to-leading order corrections to the color-suppressed tree amplitude in QCD factorization method which may be essential to solve the puzzles in $B\to ππ$ and $πK$ decays. Then we discuss the polarization puzzles in $B\to ϕK^*$ and $ρK^*$. The impacts of the newly measured $B_s-\bar B_s$ mixing

A. L. Rakhmanov, A. M. Zagoskin, Sergey Savel'ev, Franco Nori

We consider the propagation of a classical electromagnetic wave through a transmission line, formed by identical superconducting charge qubits inside a superconducting resonator. Since the qubits can be in a coherent superposition of quantum states, we show that such a system demonstrates interesting new effects, such as a ``breathing'' photonic crys

Katsutoshi Naito

Our aim in this paper is to compute the entire cyclic cohomology of noncommutative 2-tori. First of all, we clarify their algebraic structure of noncommutative 2-tori as a $F^*$-algebra, according to the idea of Elliott-Evans. Actually, they are the inductive limit of subhomogeneous $F^*$-algebras. Using such a result, we compute their entire cyclic cohomolo

Sang-Hoon Kim

The condensate fraction of a homogeneous and dilute Bose gas is expanded as a power series of $\sqrt{n a^3}$ as $N_0/N = 1 -c_1 (n a^3)^{1/2} -c_2 (n a^3) - c_3 (n a^3)^{3/2}\hdots.$ The coefficient $c_1$ is well-known as $8/3 \sqrtπ$, but the others are unknown yet. Considering two-body contact interactions and applying a canonical transformation method twi

Koji Nagata

Recently, [{arXiv:0810.3134}] is accepted and published. We show that any $N$-qubit state which is diagonal in the Greenberger-Horne-Zeilinger basis is full $N$-qubit entangled state if and only if no partial transpose of the multiqubit state is positive with respect to any partition.

Damian Burch, Martin Z. Bazant

Three-dimensional (3D) AC electro-osmotic (ACEO) pumps have recently been developed that are much faster and more robust than previous planar designs. The basic idea is to create a ``fluid conveyor belt'' by placing opposing ACEO slip velocities at different heights. Current designs involve electrodes with electroplated steps, whose heights have been

Renxin Xu

It is a pity that the real state of matter in pulsar-like stars is still not determined confidently because of the uncertainty about cold matter at supranuclear density, even 40 years after the discovery of pulsar. Nuclear matter (related to neutron stars) is one of the speculations for the inner constitution of pulsars even from the Landau's time more t

Tieyan Si, Yue yu

Exactly soluble spin-$\frac{1}2$ models on three-dimensional lattices are proposed by generalizing Kitaev model on honeycomb lattice to three dimensions with proper periodic boundary conditions. The simplest example is spins on a diamond lattice which is exactly soluble. The ground state sector of the model may be mapped into a p-wave paired state on cubic l

Pramod N. Achar

Let X be a scheme, and let G be an affine group scheme acting on X. Under reasonable hypotheses on X and G, we construct a t-structure on the derived category of G-equivariant coherent sheaves that in many ways resembles the perverse coherent t-structure, but which incorporates additional information from the G-action. Under certain circumstances, this t-str

You-Gang Feng

We defined exponential maps with one parameter, associated with geodesics on the parameter surface. By group theory we proposed a formula of the critical points, which is a direct sum of the Lie subalgebras at the critical temperature. We consider the self similar transformations as symmetric operations. In the opinion of symmetry we analyzed the hexagon lat

Akinari Hoshi, Ming-chang Kang

We will show the raitonality of some twisted symmetric group actions.

E. Kovalchuk, R. Kobes

We consider a homogeneous non-ideal Bose gas at nonzero temperature in equilibrium below the critical temperature $T_C$ in the framework of finite temperature field theory. An algorithm is described in which a manageable subset of diagrams can be considered which, coupled with a self--consistent condition related to the minimization of the free energy, can b

Antonio M. Garcia-Garcia

We study analytically the metal-insulator transition in a disordered conductor by combining the self-consistent theory of localization with the one parameter scaling theory. We provide explicit expressions of the critical exponents and the critical disorder as a function of the spatial dimensionality, $d$. The critical exponent $ν$ controlling the divergence

J. Harnad

This is a review of Lee Smolin's "The Trouble with Physics". The main gist of the review is that the physics of the past three decades has been rich with new discoveries in a large number of domains. The Standard Model, while providing a successful framework for the electroweak and strong interactions still needs to be developed further to fully

Orsola De Marco, S. Wortel, Howard E. Bond, Dianne Harmer

A radial velocity (RV) survey to detect central stars in binary systems was carried out between 2002 and 2004. De Marco et al. (2004) reported that 10 out of 11 monitored stars exhibited strong RV variability, but periods were not detected. Since other mechanisms, such as wind variability, can cause apparent RV variations, we monitored 4 of the 10 RV-variabl

Robert Kariotis

A brief discussion is given of the traditional version of the Maximum Entropy Method, including a review of some of the criticism that has been made in regard to its use in statistical inference. Motivated by these questions, a modified version of the method is proposed and applied to a simple problem, demonstrating its use in inference.

Rafe Mazzeo, Michael Singer

Let $(M,g)$ be a compact Kähler-Einstein manifold with $c_1 > 0$. Denote by $K\to M$ the canonical line-bundle, with total space $X$, and $X_0$ the singular space obtained by blowing down $X$ along its zero section. We employ a construction by Page and Pope and discuss an interesting multi-parameter family of Poincaré--Einstein metrics on $X$. One 1-paramete

C. Nepali, G. Fai, D. Keane

We have studied U+U collisions at $\sqrt{s_{NN}}$ = 200 GeV using Monte Carlo Glauber, UrQMD and AMPT models. We find that it is possible to separate central tip-tip events as well as central body-body events on the basis of cuts on multiplicity and magnitude of the reduced flow vector.

Sarah C. Case, Sidney R. Nagel

The expected universal dynamics associated with the initial stage of droplet coalescence are difficult to study visually due to the rapid motion of the liquid and the awkward viewing geometry. Here we employ an electrical method to study the coalescence of two inviscid droplets at early times. We measure the growth dynamics of the bridge connecting the two d

Longhua Hu, Alexander Y. Grosberg, Robijn Bruinsma

Conformational fluctuations are believed to play an important role in the process by which transcription factor proteins locate and bind their target site on the genome of a bacterium. Using a simple model, we show that the binding time can be minimized, under selective pressure, by adjusting the spectrum of conformational states so that the fraction of time

Brian Niebergal, Rachid Ouyed, Denis Leahy

The recently suggested correlation between the surface temperature and the magnetic field in isolated neutron stars does not seem to work well for SGRs, AXPs and X-ray dim isolated neutron stars (XDINs; specifically the Magnificent Seven or M7). Instead by appealing to a Color-Flavor Locked Quark Star (CFLQS) we find a more natural explanation. In this pictu

Zygmunt Lalak

Moduli with flat or run-away classical potentials are generic in theories based on supersymmetry and extra dimensions. They mix between themselves and with matter fields in kinetic terms and in the nonperturbative superpotentials. As the result, interesting structure appears in the scalar potential which helps to stabilise and trap moduli and leads to multi-

J. H. Krolik

With the fundamental stress mechanism of accretion disks identified--correlated MHD turbulence driven by the magneto-rotational instability--it has become possible to make numerical simulations of accretion disk dynamics based on well-understood physics. A sampling of results from both Newtonian 3-d shearing box and general relativistic global disk MHD simul

S. Hild, A. Freise

We introduce a concept that uses detuned arm cavities to increase the shot noise limited sensitivity of LIGO without increasing the light power inside the arm cavities. Numerical simulations show an increased sensitivity between 125 and 400 Hz, with a maximal improvement of about 80% around 225 Hz, while the sensitivity above 400Hz is decreased. Furthermore

J. R. Maund, J. C. Wheeler, F. Patat, L. Wang

We present spectropolarimetric observations of the Type IIb SN 2001ig in NGC 7424; conducted with the ESO VLT FORS1 on 2001 Dec 16, 2002 Jan 3 and 2002 Aug 16 or 13, 31 and 256 days post-explosion. These observations are at three different stages of the SN evolution: (1) The hydrogen-rich photospheric phase, (2) the Type II to Type Ib transitional phase and

R. N. Mohapatra, Nobuchika Okada, Hai-Bo Yu

Existence of color sextet diquark Higgs fields with TeV masses will indicate a fundamentally different direction for unification than conventional grand unified theories. There is a class of partial unification models based on the gauge group $SU(2)_L\times SU(2)_R\times SU(4)_c$ that implement the seesaw mechanism for neutrino mass with seesaw scale around

A. Mezzacappa, S. W. Bruenn, J. M. Blondin, W. R. Hix

Here we present the results from two sets of simulations, in two and three spatial dimensions. In two dimensions, the simulations include multifrequency flux-limited diffusion neutrino transport in the "ray-by-ray-plus" approximation, two-dimensional self gravity in the Newtonian limit, and nuclear burning through a 14-isotope alpha network. The thre

Sergei Dubovsky, Alberto Nicolis, Enrico Trincherini, Giovanni Villadoro

It is well known that in Lorentz invariant quantum field theories in flat space the commutator of space-like separated local operators vanishes (microcausality). We provide two different arguments showing that this is a consequence of the causal structure of the classical theory, rather than of Lorentz invariance. In particular, microcausality holds in arbit

Ekaterina Pozdeeva

The Sukumar theorem about the connection between the Green functions of the supersymmetric pair of the Schrödinger Hamiltonians is generalized to the case of the supersymmetric pair of the Dirac Hamiltonians.

Patricia Hersh, Samuel K. Hsiao

Conditions are provided under which an endomorphism on quasisymmetric functions gives rise to a left random walk on the descent algebra which is also a lumping of a left random walk on permutations. Spectral results are also obtained. Several well-studied random walks are now realized this way: Stanley's QS-distribution results from endomorphisms given b

P. Chylek, M. R. Perez

We assess the possibility that planets Gliese 581 c and d are within the habitable zone. In analogy with our solar system, we use an empirical definition of the habitable zone. We include assumptions such as planetary climates, and atmospheric circulation on gravitationally locked synchronous rotation. Based on the different scenarios, we argue that both pla

Masahiro Teshima, Elisa Prandini, Rudolf Bock, Manel Errando

The quasar 3C 279 is one of the best-studied flat spectrum radio quasars. It is located at a comparatively large redshift of z=0.536: E>100 GeV observations of such distant sources were until recently impossible both due to the expected steep energy spectrum and the expected attenuation of the gamma-rays by the extragalactic background light. Here we present

Konstantinos Tassis

The surface density of the star formation rate in different galaxies, as well as in different parts of a single galaxy, scales nonlinearly with the surface density of the total gas. This observationally established relation is known as the Kennicutt-Schmidt star formation law. The slope of the star formation law has been shown to change with the density of t

Jan Pflamm-Altenburg, Carsten Weidner, Pavel Kroupa

Star-formation rates (SFRs) of galaxies are commonly calculated by converting the measured Halpha luminosities (L_Halpha) into current SFRs. This conversion is based on a constant initial mass function (IMF) independent of the total SFR. As recently recognised the maximum stellar mass in a star cluster is limited by the embedded total cluster mass and, in ad

Sarah J. U. Higdon, James L. Higdon

We present Spitzer observations of Tidal Dwarf Galaxies (TDGs) in three interacting systems: NGC 5291, Arp105 and Stephan's Quintet. The spectra show bright emission from polyaromatic hydrocarbons (PAHs), nebular lines and warm molecular hydrogen, characteristic of recent episodes of star formation. The PAH emission that falls in the IRAC 8.0 micron band

Kay Huebner

We investigate correlation functions of the Polyakov loop and static meson/diquark systems with the chiral condensate and the quark number density at finite temperature. In particular the latter observable can give insight in the mechanism of screening and string breaking at finite temperature. We use for our analysis gauge field configurations generated in

D. T. N. Chen, A. W. C. Lau, L. A. Hough, M. F. Islam

We probe non-equilibrium properties of an active bacterial bath through measurements of correlations of passive tracer particles and the response function of a driven, optically trapped tracer. These measurements demonstrate violation of the fluctuation-dissipation theorem and enable us to extract the power spectrum of the active stress fluctuations. In some

Hudong Chen, Isaac Goldhrish, Steven Orszag

Conventional lattice Boltzmann models only satisfy moment isotropy up to fourth order. In order to accurately describe improtant physical effects beyond the isothermal Navier-Stokes fluid regime, higher order isotropy is required. In this paper, we present some basic results on moment isotropy and its relationship to the rotational symmetry of a generating d

M. Gaug, C. Hsu, J. K. Becker, A. Biland

The MAGIC telescope located on the Roque de los Muchachos on the Canary Island La Palma at a height of 2200 m a.s.l. is able to point to the sea. This permits a search for air shower signatures induced by particles coming out of the Earth. An analytical approximation results in tau neutrino effective areas from ~10^3 m^2 (at 100 TeV) to 10^5 m^2 (at 1 EeV) f

Antal Balog, Alina Cojocaru, Chantal David

Let E be an elliptic curve over Q. In 1988, Koblitz conjectured a precise asymptotic for the number of primes p up to x such that the order of the group of points of E over the finite field F_p is prime. This is an analogue of the Hardy and Littlewood twin prime conjecture in the case of elliptic curves. Koblitz's conjecture is still widely open. In this

Ruslan Sharipov

Smooth deformations of a Minkowski type metric in a four-dimensional space-time manifold are considered. Deformations of the basic spin-tensorial fields associated with this metric are calculated and their application to calculating the energy-momentum tensor of a massive spin 1/2 particle is shown.

Philip B. Allen

Spin-orbit interaction lifts accidental band degeneracy. The geometric phase gamma(C)=pi for circuits surrounding a line of such degeneracy cannot survive completely unchanged. The change depends on how the spin is fixed during adiabatic evolution. For spin fixed along the internal spin-orbit field, gamma(C) decreases to zero as the circuit collapses around

Takis Konstantopoulos, Andreas Kyprianou, Marina Sirvio, Paavo Salminen

We consider a stochastic fluid queue served by a constant rate server and driven by a process which is the local time of a certain Markov process. Such a stochastic system can be used as a model in a priority service system, especially when the time scales involved are fast. The input (local time) in our model is always singular with respect to the Lebesgue

Raz Kupferman, Claude Mangoubi, Edriss S. Titi

We derive a criterion for the breakdown of solutions to the Oldroyd-B model in $\R^3$ in the limit of zero Reynolds number (creeping flow). If the initial stress field is in the Sobolev space $H^m$, $m> 5/2$, then either a unique solution exists within this space indefinitely, or, at the time where the solution breaks down, the time integral of the $L^\infty

A. Fortier, O. G. Benvenuto, A. Brunini

Aims. In the context of the core instability model, we present calculations of in situ giant planet formation. The oligarchic growth regime of solid protoplanets is the model adopted for the growth of the core. Methods. The full differential equations of giant planet formation were numerically solved with an adaptation of a Henyey-type code. The planetesimal

Vincent Bouchard, Albrecht Klemm, Marcos Marino, Sara Pasquetti

We propose a complete, new formalism to compute unambiguously B-model open and closed amplitudes in local Calabi-Yau geometries, including the mirrors of toric manifolds. The formalism is based on the recursive solution of matrix models recently proposed by Eynard and Orantin. The resulting amplitudes are non-perturbative in both the closed and the open modu

Parthapratim Biswas, Raymond Atta-Fynn, David A. Drabold

We have extended our experimentally constrained molecular relaxation technique (P. Biswas {\it et al}, Phys. Rev. B {\bf 71} 54204 (2005)) to hydrogenated amorphous silicon: a 540-atom model with 7.4 % hydrogen and a 611-atom model with 22 % hydrogen were constructed. Starting from a random configuration, using physically relevant constraints, {\it ab initio

V. Prudnikov, P. Prudnikov, A. Vakilov, A. Krinitsyn

The critical behavior of the disordered ferromagnetic Ising model is studied numerically by the Monte Carlo method in a wide range of variation of concentration of nonmagnetic impurity atoms. The temperature dependences of correlation length and magnetic susceptibility are determined for samples with various spin concentrations and various linear sizes. The

Stephen Semmes

The special case of closed subsets of C^n is briefly discussed.

Ginestra Bianconi, Natali Gulbahce

We derive a Belief-Propagation algorithm for counting large loops in a directed network. We evaluate the distribution of the number of small loops in a directed random network with given degree sequence. We apply the algorithm to a few characteristic directed networks of various network sizes and loop structures and compare the algorithm with exhaustive coun

Richard H. Durisen, Thomas W. Hartquist, Megan K. Pickett

Numerical hydrodynamics simulations have established that disks which are evolved under the condition of local isothermality will fragment into small dense clumps due to gravitational instabilities when the Toomre stability parameter $Q$ is sufficiently low. Because fragmentation through disk instability has been suggested as a gas giant planet formation mec

Zehua Zhou, Min Zhu

Let $g$ be a holomorphic map of $B$, where $B$ is the unit ball of ${C}^n$. Let $0<p<+\infty, -n-1<q<+\infty$, $q>-1$ and $α>0$. This paper gives some necessary and sufficient conditions for the Extended Ces$\acute{a}$ro Operators induced by $g$ to be bounded or compact between generalized Besov space $B(p,q)$ and $α$- Bloch space ${\mathcal B}^α.$

Daniel S. Baum, Helmut Bölcskei

The large majority of commercially available multiple-input multiple-output (MIMO) radio channel measurement devices (sounders) is based on time-division multiplexed switching (TDMS) of a single transmit/receive radio-frequency chain into the elements of a transmit/receive antenna array. While being cost-effective, such a solution can cause significant measu

Rupali Chandar, S. Michael Fall, Dean E. McLaughlin

We have constructed the mass function of globular star clusters in the Sombrero galaxy in bins of different internal half-mass density rho_h and projected galactocentric distance R. This is based on the published measurements of the magnitudes and effective radii of the clusters by Spitler et al. (2006) in BVR images taken with the ACS on HST. We find that t

Julio I. de Vicente, Jorge Sánchez-Ruiz

Entropic uncertainty relations place nontrivial lower bounds to the sum of Shannon information entropies for noncommuting observables. Here we obtain a novel lower bound on the entropy sum for general pairs of observables in finite-dimensional Hilbert space, which improves on the best bound known to date [Maassen and Uffink, Phys. Rev. Lett. 60, 1103 (1988)]

João Costa, Mário Pimenta, Bernardo Tomé

Geant4 is a Monte Carlo radiation transport toolkit that is becoming a tool of generalized application in areas such as high-energy physics, nuclear physics, astroparticle physics, or medical physics. Geant4 provides an optical physics process category, allowing the simulation of the production and propagation of light. Its capabilities are well tailored for

Zhong-Shan Fang, Ze-Hua Zhou

Let $g$ be a holomorphic function of the unit ball $B$ in the $n$-dimensional space, and denote by $T_g$ and $I_g$ the induced extended Ces$\acute{a}$ro operator and another integral operator. The boundedness and compactness of $T_g$ and $I_g$ acting on the Zygmund spaces in the unit ball are discussed and necessary and sufficient conditions are given in thi

Zhongshan Fang, Zehua Zhou

In 1987, Shapiro shew that composition operator induced by symbol $ϕ$ is compact on the Lipschltz space if and only if the infinity norm of $ϕ$ is less than 1 by a spectral-theoretic argument, where $ϕ$ is a holomorphic self-map of the unit disk. In this paper, we shall generalize Shapiro&#39;s result to the $n$-dimensional case.

Viktor Begun, Mark Gorenstein

Particle number fluctuations are studied in the ideal pion gas approaching Bose-Einstein condensation. Two different cases are considered: Bose condensation of pions at large charge densities $ρ_Q$ and Bose condensation at large total densities of pions $ρ_π$. Calculations are done in grand canonical, canonical and microcanonical ensembles. At high collision

Zhong-Shan Fang, Ze-Hua Zhou

Let $ϕ(z)=(ϕ_1(z),...,ϕ_n(z))$ be a holomorphic self-map of $B_n$ and $ψ(z)$ a holomorphic function on $B_n$, and $H(B_n)$ the class of all holomorphic functions on $B_n$, where $B_n$ is the unit ball of $C^n$, the weight composition operator $W_{ψ,ϕ}$ is defined by $W_{ψ,ϕ}=ψf(ϕ)$ for $f\in H(B_n)$. In this paper we estimate the essential norm for the weigh

Zhongshan Fang, Zehua Zhou

This paper gives some simple estimates of the essential norm for the difference of composition operators induced by $ϕ$ and $ψ$ acting on bounded function space in the unit polydiscs $U^n$, where $ϕ(z)$ and $ψ(z)$be holomorphic self-maps of $U^n$. As its applications, a characterization of compact difference is given for composition operators acting on the b

Damian Heard, Ekaterina Pervova, Carlo Petronio

We enumerate all spaces obtained by gluing in pairs the faces of the octahedron in an orientation-reversing fashion. Whenever such a gluing gives rise to non-manifold points, we remove small open neighbourhoods of these points, so we actually deal with three-dimensional manifolds with (possibly empty) boundary. There are 298 combinatorially inequivalent glui

Mark Gorenstein

The multiplicity fluctuations of hadrons are studied within the statistical hadron-resonance gas model in the large volume limit. The role of quantum statistics and resonance decay effects are discussed. The microscopic correlator method is used to enforce conservation of three charges -- baryon number, electric charge, and strangeness -- in the canonical en

B. Gato-Rivera, A. N. Schellekens

We consider non-supersymmetric four-dimensional closed string theories constructed out of tensor products of N=2 minimal models. Generically such theories have closed string tachyons, but these may be removed either by choosing a non-trivial partition function or a suitable Klein bottle projection. We find large numbers of examples of both types.

Gianni Dal Maso, Irene Fonseca, Giovanni Leoni, Massimiliano Morini

The one-dimensional version of the higher order total variation-based model for image restoration proposed by Chan, Marquina, and Mulet in [4] is analyzed. A suitable functional framework in which the minimization problem is well posed is being proposed and it is proved analytically that the higher order regularizing term prevents the occurrence of the stair

M. Gilowski, T. Wendrich, T. Müller, Ch. Jentsch

We report the first implementation of a Gauss sum factorization algorithm by an internal state Ramsey interferometer using cold atoms. A sequence of appropriately designed light pulses interacts with an ensemble of cold rubidium atoms. The final population in the involved atomic levels determines a Gauss sum. With this technique we factor the number N=263193

Zhong-Shan Fang, Ze-Hua Zhou

Let $ϕ$ and $ψ$ be holomorphic self-maps of the unit polydisc $U^n$ in the $n$-dimensional complex space, and denote by $C_ϕ$ and $C_ψ$ the induced composition operators. This paper gives some simple estimates of the essential norm for the difference of composition operators $C_ϕ-C_ψ$ from Bloch space to bounded holomorphic function space in the unit polydis

S. Brazovskii, S. I. Matveenko

We suggest a theory of internal coherent tunneling in the pseudogap region, when the applied voltage U is below the free electron gap 2Delta_0. We address quasi 1D systems, where the gap is originated by spontaneous lattice distortions of the Incommensurate Charge Density Wave (ICDW) type. Results can be adjusted also to quasi-1D superconductors. The instant

David Snoke

A simple set of formulas is presented which allows prediction of the fraction of ionized carriers in an electron-hole-exciton gas in a photoexcited semiconductor. These results are related to recent experiments with excitons in single and double quantum wells.

JF Donati, MM Jardine, SG Gregory, P Petit

From observations collected with the ESPaDOnS spectropolarimeter, we report the discovery of magnetic fields at the surface of the mildly accreting classical T Tauri star V2129 Oph. Zeeman signatures are detected, both in photospheric lines and in the emission lines formed at the base of the accretion funnels linking the disc to the protostar, and monitored

Carlos Mejia-Monasterio, Hannu Wichterich

We discuss the problem of heat conduction in quantum spin chain models. To investigate this problem it is necessary to consider the finite open system connected to heat baths. We describe two different procedures to couple the system with the reservoirs: a model of stochastic heat baths and the quantum trajectories solution of the quantum master equation. Th

D. Tescaro, H. Bartko, N. Galante, F. Goebel

In February 2007 the MAGIC Air Cherenkov Telescope for gamma-ray astronomy was fully upgraded with an ultra fast 2 GSamples/s digitization system. Since the Cherenkov light flashes are very short, a fast readout can minimize the influence of the background from the light of the night sky. Also, the time structure of the event is an additional parameter to re

Chih-Piao Chuu, Ming-Che Chang, Qian Niu

By viewing the electron as a wavepacket in the positive energy spectrum of the Dirac equation, we are able to achieve a much clearer understanding of its behavior under weak electromagnetic fields. The intrinsic spin magnetic moment is found to be established from the self-rotation of the wavepacket. A non-canonical structure is also exhibited in the equatio

Artie P. Hatzes, Mathias Zechmeister

We present the results of a long time series of precise stellar radial velocity measurements of the planet hosting K giant star Beta Geminorum. A total of 20 hours of observations spanning three nights were obtained and the radial velocity variations show the presence of solar-like stellar oscillations. Our period analysis yields six significant pulsation mo

Pascal Perrier, Joseph Perkell, Yohan Payan, Majid Zandipour

A number of studies carried out on different languages have found that tongue movements in speech are made along two primary degrees of freedom (d.f.s): the high-front to low-back axis and the high-back to low-front axis. We explore the hypothesis that these two main d.f.s could find their origins in the physical properties of the vocal tract. A large set of

Guillaume Lucas, Laurent Pizzagalli

The recombination of Frenkel pairs resulting from low energy recoils in 3C-SiC has been investigated using first principles and Nudged Elastic Band calculations. Several recombination mechanisms have been obtained, involving direct interstitial migration, atoms exchange, or concerted displacements, with activation energies ranging from 0.65 eV to 1.84 eV. Th

O. M. Lecian, G. Montani

We analyze the dynamical implications of an exponential Lagrangian density for the gravitational field, as referred to an isotropic FRW Universe. Then, we discuss the features of the generalized deSitter phase, predicted by the new Friedmann equation. The existence of a consistent deSitter solution arises only if the ratio between the vacuum-energy density a

Frédéric Le Roux

Gambaudo and Pécou introduced the ``linking property&#39;&#39; to study the dynamics of germs of planar homeomorphims and provide a new proof of Naishul theorem in their paper &#34;A topological invariant for volume preserving diffeomorphisms&#34; (Ergodic Theory Dynam. Systems 15 (1995), no. 3, 535--541). In this paper we prove that the negation of Gambaudo

Claude Pasquier, Fabrice Girardot, Karim Jevardat De Fombelle, Richard Christen

MOTIVATION: Microarray technology makes it possible to measure thousands of variables and to compare their values under hundreds of conditions. Once microarray data are quantified, normalized and classified, the analysis phase is essentially a manual and subjective task based on visual inspection of classes in the light of the vast amount of information avai

Jean-Pierre Kahane

We describe a brownian quasi-helix in R^4 by means of an automatic sequence

M. Sarzi, R. Bacon, M. Cappellari, R. L. Davies

Motivated by recent progress in the study of early-type galaxies owing to technological advances, the launch of new space telescopes and large ground-based surveys, we attempt a short review of our current understanding of the recent star-formation activity in such intriguing galactic systems.

A. Titov, B. Kampfer

We discuss an asymmetry of the decay $ω->e^+e^-$ in nuclear matter with respect to the electron and positron energies. This asymmetry is sensitive to the properties of the $ω$ meson self-energy and, in particular, it has a non-trivial dependence on the $ω$ energy and momentum. Therefore, this asymmetry may serve as a powerful tool in studying the properties