July 2007 arXiv papers — page 6

S. A. Appleby, R. A. Battye

We consider a thick p-brane embedded in an n-dimensional spacetime possessing radial symmetry in the directions orthogonal to the brane. We first consider a static brane, and find a general fine tuning relationship between the brane and bulk parameters required for the brane to be flat. We then consider the cosmology of a time dependent brane in a static bul

V. Casasola, F. Combes, D. Bettoni, G. Galletta

We investigate the molecular gas content and the excitation and fragmentation properties in the central region of the spiral galaxy Messier 81 in both the ^{12}CO(1-0) and ^{12}CO(2-1) transitions. We have recently observed the two transitions of CO in the M~81 center with A, B, and HERA receivers of the IRAM 30-m telescope. We find no CO emission in the inn

Anindita Banerjee, Anirban Pathak

Reversible circuits for SR flip flop, JK flip flop, D flip flop, T flip flop, Master Slave D flip flop and Master Slave JK flip flop have been provided with three different logical approaches. All the circuits have been optimized with the help of existing local optimization algorithms (e.g. template matching, moving rule and deletion rule) and the optimized

Michael Kapovich

We provide the details for Gromov's proof of Stallings' theorem on groups with infinitely many ends using harmonic functions. The main technical result of the paper is a compactness theorem for a certain family of harmonic functions.

Marco Polini, Reza Asgari, Giovanni Borghi, Yafis Barlas

We report on a theoretical study of the influence of electron-electron interactions on ARPES spectra in graphene that is based on the random-phase-approximation and on graphene's massless Dirac equation continuum model. We find that level repulsion between quasiparticle and plasmaron resonances gives rise to a gap-like feature at small k. ARPES spectra a

B. Kaviraj, F. Alves

The resistive and reactive components of magneto-impedance (MI) for Finemet/Copper/Finemet sandwiched structures based on stress-annealed nanocrystalline Fe75Si15B6Cu1Nb3 ribbons as functions of different fields (longitudinal and perpendicular) and frequencies have been measured and analyzed. Maximum magneto-resistance and magneto-inductance ratios of 700% a

Kyung Taec Kim, Kyung Sik Kang, Mi Na Park, Tayyab Imran

The attosecond high harmonic pulses obtained from a long Ar-filled gas cell were characterized by two techniques - the reconstruction of attosecond beating by interference of two-photon transition (RABITT) and frequency-resolved optical gating (FROG) methods. The pulse durations obtained by RABITT and FROG methods agreed within 10 %.

V. M. Kalita, I. M. Ivanova, V. M. Loktev

The theoretical description of quantum phase transition, induced by the external magnetic field, into antiferromagnetic state in the van Vleck - singlet - magnet with a single-ion anisotropy of "easy-plane" type and ion spin S=1 is proposed. It is shown that the spin polarization of the ground non-degenerated state proves to be the order parameter of

Chengming Bai

In this paper, the different operator forms of classical Yang-Baxter equation are given in the tensor expression through a unified algebraic method. It is closely related to left-symmetric algebras which play an important role in many fields in mathematics and mathematical physics. By studying the relations between left-symmetric algebras and classical Yang-

Eduard P. Kontar, A. Gordon Emslie, Anna Maria Massone, Michele Piana

Although both electron-ion and electron-electron bremsstrahlung contribute to the hard X-ray emission from solar flares, the latter is normally ignored. Such an omission is not justified at electron (and photon) energies above $\sim 300$ keV, and inclusion of the additional electron-electron bremsstrahlung in general makes the electron spectrum required to p

Kang-Min Kim, Inwoo Han, Gennady G. Valyavin, Sergei Plachinda

We introduce a new polarimeter installed on the high-resolution fiber-fed echelle spectrograph (called BOES) of the 1.8-m telescope at the Bohyunsan Optical Astronomy Observatory, Korea. The instrument is intended to measure stellar magnetic fields with high-resolution (R $\sim$ 60000) spectropolarimetric observations of intrinsic polarization in spectral li

Huitao Feng, Guangbo Xu, Weiping Zhang

We present an alternate proof of the Bismut-Zhang localization formula for $η$-invariants without using the analytic techniques developed by Bismut-Lebeau. A Riemann-Roch property for Chern-Simons currents, which is of independent interest, is established in due course.

Marco Fuhrman, Ying Hu, Gianmario Tessitore

In this paper we introduce a new kind of Backward Stochastic Differential Equations, called ergodic BSDEs, which arise naturally in the study of optimal ergodic control. We study the existence, uniqueness and regularity of solution to ergodic BSDEs. Then we apply these results to the optimal ergodic control of a Banach valued stochastic state equation. We al

Zhangjin Chen, Toru Morishita, Anh-Thu Le, C. D. Lin

We analyzed the two-dimensional (2D) electron momentum distributions of high-energy photoelectrons of atoms in an intense laser field using the second-order strong field approximation (SFA2). The SFA2 accounts for the rescattering of the returning electron with the target ion to first order and its validity is established by comparing with results obtained b

Cheongho Han

We classify various types of planetary lensing signals and the channels of detecting them. We estimate the relative frequencies of planet detections through the individual channels with special emphasis on the new channels to be additionally provided by future lensing experiments that will survey wide fields continuously at high cadence by using very large-f

Adam Boocher, Jay Daigle, Jim Hoste, Wenjing Zheng

A Lissajous knot is one that can be parameterized by a single cosine function in each coordinate. Lissajous knots are highly symmetric, and for this reason, not all knots are Lissajous. We prove several theorems which allow us to place bounds on the number of Lissajous knot types with given frequencies and to efficiently sample all possible Lissajous knots w

B. Ananthanarayan, Keshav Choudhary, Lishibanya Mohapatra, Indrajeet Patil

We review the recent discoveries of rare oscillation phenomena in certain heavy neutral meson systems.

B. Ananthanarayan, Keshav Choudhary, Lishibanya Mohapatra, Indrajeet Patil

We review the recent discoveries of exotic heavy baryons at the Fermi National Accelerator Laboratory.

Alexei Borodin, Patrik L. Ferrari, Tomohiro Sasamoto

We consider the polynuclear growth (PNG) model in 1+1 dimension with flat initial condition and no extra constraints. The joint distributions of surface height at finitely many points at a fixed time moment are given as marginals of a signed determinantal point process. The long time scaling limit of the surface height is shown to coincide with the Airy_1 pr

Giordano Pola, Paulo Tabuada

Symbolic models are abstract descriptions of continuous systems in which symbols represent aggregates of continuous states. In the last few years there has been a growing interest in the use of symbolic models as a tool for mitigating complexity in control design. In fact, symbolic models enable the use of well known algorithms in the context of supervisory

Pablo A. Ferrari, James B. Martin

In the Hammersley-Aldous-Diaconis process infinitely many particles sit in R and at most one particle is allowed at each position. A particle at x$ whose nearest neighbor to the right is at y, jumps at rate y-x to a position uniformly distributed in the interval (x,y). The basic coupling between trajectories with different initial configuration induces a pro

Raphael Ponge

In this paper we explain how to define "lower dimensional'' volumes of any compact Riemannian manifold as the integrals of local Riemannian invariants. For instance we give sense to the area and the length of such a manifold in any dimension. Our reasoning is motivated by an idea of Connes and involves in an essential way noncommutative geometry

P. Castelo Ferreira, J. Dias de Deus

We compute QCD corrections to QED calculations for vacuum polarization in background magnetic fields. Formally, the diagram for virtual $e\bar{e}$ loops is identical to the one for virtual $q\bar{q}$ loops. However due to confinement, or to the growth of $α_s$ as $p^2$ decreases, a direct calculation of the diagram is not allowed. At large $p^2$ we consider

Anders J. Frankild, Sean Sather-Wagstaff, Roger Wiegand

Let $(R,\m)$ and $(S,\n)$ be commutative Noetherian local rings, and let $ϕ:R\to S$ be a flat local homomorphism such that $\m S = \n$ and the induced map on residue fields $R/\m \to S/\n$ is an isomorphism. Given a finitely generated $R$-module $M$, we show that $M$ has an $S$-module structure compatible with the given $R$-module structure if and only if $\

Kay-Yut Chen, Tad Hogg

We describe human-subject laboratory experiments on probabilistic auctions based on previously proposed auction protocols involving the simulated manipulation and communication of quantum states. These auctions are probabilistic in determining which bidder wins, or having no winner, rather than always having the highest bidder win. Comparing two quantum prot

A. E. Feiguin, F. Heidrich-Meisner

We study the properties of a one-dimensional (1D) gas of fermions trapped in a lattice by means of the density matrix renormalization group method, focusing on the case of unequal spin populations, and strong attractive interaction. In the low density regime, the system phase-separates into a well defined superconducting core and a fully polarized metallic c

H. -O. Kreiss, O. Reula, O. Sarbach, J. Winicour

In recent work, we used pseudo-differential theory to establish conditions that the initial-boundary value problem for second order systems of wave equations be strongly well-posed in a generalized sense. The applications included the harmonic version of the Einstein equations. Here we show that these results can also be obtained via standard energy estimate

Igor F. Herbut, Vladimir Juricic, Oskar Vafek

We argue that the unscreened Coulomb interaction in graphene provides a positive, universal, and logarithmic correction to scaling of zero-temperature conductivity with frequency. The combined effect of the disorder due to wrinkling of the graphene sheet and the long range electron-electron interactions is a finite positive contribution to the dc conductivit

Teodor Banica, Jean-Marc Schlenker

This paper has been withdrawn by the authors, the main result being known since Lam and Leung, J. Algebra 2000.

Francesco de Bernardis, Alessandro Melchiorri, Licia Verde, Raul Jimenez

We discuss the cosmological degeneracy between the age of the Universe, the Hubble parameter and the effective number of relativistic particles N_eff. We show that independent determinations of the Hubble parameter H(z) as those recently provided by Simon,Verde, Jimenez (2006), combined with other cosmological data sets can provide the most stringent constra

Miloš Ilak, Clarence W. Rowley

We study reduced-order models of three-dimensional perturbations in linearized channel flow using balanced proper orthogonal decomposition (BPOD). The models are obtained from three-dimensional simulations in physical space as opposed to the traditional single-wavenumber approach, and are therefore better able to capture the effects of localized disturbances

J. J. Dudek, R. G. Edwards, N. Mathur, D. G. Richards

Working with a large basis of covariant derivative-based meson interpolating fields we demonstrate the feasibility of reliably extracting multiple excited states using a variational method. The study is performed on quenched anisotropic lattices with clover quarks at the charm mass. We demonstrate how a knowledge of the continuum limit of a lattice interpola

D. Gross, M. Van den Nest

We report progress on the LU-LC conjecture - an open problem in the context of entanglement in stabilizer states (or graph states). This conjecture states that every two stabilizer states which are related by a local unitary operation, must also be related by a local operation within the Clifford group. The contribution of this paper is a reduction of the LU

J. Marvin Herndon

One of the most fundamental problems in physics has been to understand the nature of the mechanism that generates the geomagnetic field and the magnetic fields of other planets and satellites. For decades, the dynamo mechanism, thought to be responsible for generating the geomagnetic field and other planetary magnetic fields, has been ascribed to convection

Jacob Fox, Benny Sudakov

In this paper, we present several density-type theorems which show how to find a copy of a sparse bipartite graph in a graph of positive density. Our results imply several new bounds for classical problems in graph Ramsey theory and improve and generalize earlier results of various researchers. The proofs combine probabilistic arguments with some combinatori

Daniel Braun, John Martin

We study a two-level atom in a double--well potential coupled to a continuum of electromagnetic modes (black body radiation in three dimensions at zero absolute temperature). Internal and external degrees of the atom couple due to recoil during emission of a photon. We provide a full analysis of the problem in the long wavelengths limit up to the border of t

F. Becattini

In order to determine the chemical freeze-out parameters of the hadron-emitting source in relativistic heavy ion collisions some studies in literature perform fits by using as data input a subsample of ratios calculated out of experimentally measured hadron yields instead of yields themselves. We show that this is a statistically incorrect method fit, implyi

KLOE collaboration

The KLOE collaboration has searched for the phi to K0 K0bar gamma decay using a sample of 1.4 fb-1 of e+e- collisions at W ~ M(phi) collected with the KLOE experiment at the Frascati e+e- collider DAFNE. No previous search exists for this decay, while many theory models predict a BR of 10-8 for this channel. We set a preliminary value of the U.L. on this BR

Michael Arnold, Tobias Langenbruch, Johann Kroha

We propose a physical realization of the two-channel Kondo (2CK) effect, where a dynamical defect in a metal has a unique ground state and twofold degenerate excited states. In a wide range of parameters the interactions with the electrons renormalize the excited double downward below the bare defect ground state, thus stabilizing the 2CK fixed point. In add

Carlo Nipoti, James Binney

In colour-magnitude diagrams most galaxies fall in either the ``blue cloud'' or the ``red sequence'', with the red sequence extending to significantly brighter magnitudes than the blue cloud. The bright-end of the red sequence comprises elliptical galaxies (Es) with boxy isophotes and luminosity profiles with shallow central cores, while fain

Nobuyuki Kanematsu, Shunsuke Yonai, Azusa Ishizaki

A new variant of the pencil-beam (PB) algorithm for dose distribution calculation for radiotherapy with protons and heavier ions, the grid-dose spreading (GDS) algorithm, is proposed. The GDS algorithm is intrinsically faster than conventional PB algorithms due to approximations in convolution integral, where physical calculations are decoupled from simple g

Misha Kozlov, Arif Shoshi, Wenchang Xiang

We study the effect of gluon number fluctuations (Pomeron loops) on deep inelastic scattering (DIS) in the fixed coupling case. We find that the description of the DIS data is improved once gluon number fluctuations are included. Also the values of the parameters, like the saturation exponent and the diffussion coefficient, turn out reasonable and agree with

Klaus Niederkrüger, Federica Pasquotto

In this paper we present a method to obtain resolutions of symplectic orbifolds arising from symplectic reduction of a Hamiltonian S^1-manifold at a regular value. As an application, we show that all isolated cyclic singularities of a symplectic orbifold admit a resolution and that pre-quantisations of symplectic orbifolds are symplectically fillable by a sm

Amaël Broustet

We prove that Seshadri constants of some ample divisors are bigger than 1 on smooth threefolds whose anticanonical bundle is nef or on Fano varieties of small coindice. The main tools are (some known cases of) the Kawamata's effective non-vanishing conjecture and the adjunction theory. We prove the non-vanishing conjecture in dimension 3 in the case of l

Bartosz Zralek

In this article we present applications of smooth numbers to the unconditional derandomization of some well-known integer factoring algorithms. We begin with Pollard's $p-1$ algorithm, which finds in random polynomial time the prime divisors $p$ of an integer $n$ such that $p-1$ is smooth. We show that these prime factors can be recovered in deterministi

Derek Homeier, Nicole F. Allard, Christine M. S. Johnas, Peter H. Hauschildt

We present PHOENIX atmosphere models for metal-rich cool white dwarfs using improved line shapes for the Na I and K I resonance doublets. Profiles for collisional broadening due to H2 and He based on the adiabatic representation show strong deviations from Van der Waals interaction at short distances. Comparison with observed spectra that show extremely broa

A. Shindler

I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the effects of these discretization errors on the phase structure for Wilson-like fermions in the chiral limit. The possibil

Chao Tian, Jun Chen, Suhas Diggavi

We consider the multiuser successive refinement (MSR) problem, where the users are connected to a central server via links with different noiseless capacities, and each user wishes to reconstruct in a successive-refinement fashion. An achievable region is given for the two-user two-layer case and it provides the complete rate-distortion region for the Gaussi

Helena Mihaljevic-Brandt

A transcendental entire function f is called geometrically finite if the intersection of the set of singular values with the Fatou set is compact and the intersection of the postsingular set with the Julia set is finite. (In particular, this includes all entire functions with finite postsingular set.) If f is geometrically finite, then the Fatou set of f is

KLOE collaboration, F. Ambrosino, A. Antonelli, M. Antonelli

Using ~600 pb-1 collected with the KLOE detector at DAPhiNE, we have studied the production cross section of pi+ pi- pi0 pi0 and p0p0 gamma final states in e+e- collisions at center of mass energies between 1000 and 1030 MeV. By fitting the observed interference pattern around Mphi for both final states, we extract a measurement (preliminary) for the ratio G

Yue Yu, Kun Yang

Supersymmetry is assumed to be a basic symmetry of the world in many high energy theories, but none of the super partners of any known elementary particle has been observed yet. We argue that supersymmetry can also be realized and studied in ultracold atomic systems with a mixture of bosons and fermions, with properly tuned interactions and single particle d

Cedric Chanal, Werner Krauth

In this Letter, we use a general renormalization-group algorithm to implement Propp and Wilson's "coupling from the past" approach to complex physical systems. Our algorithm follows the evolution of the entire configuration space under the Markov chain Monte Carlo dynamics from parts of the configurations (patches) on increasing length scales, an

Wen-Yu Wen

In this note we study the first-order Hawking-Page phase transition of R-charged black hole in truncated Anti-de Sitter space of various dimensions. This corresponds to confinement/deconfinement phase transition in the dual gauge field theory with fixed chemical potential. We demonstrate in general this critical temperature decreases with increasing charge d

D. Stich, J. Zhou, T. Korn, R. Schulz

We have studied the spin dynamics of a high-mobility two-dimensional electron system in a GaAs/Al_{0.3}Ga_{0.7}As single quantum well by time-resolved Faraday rotation and time-resolved Kerr rotation in dependence on the initial degree of spin polarization, P, of the electrons. By increasing the initial spin polarization from the low-P regime to a significan

Andreas Sinner, Nils Hasselmann, Peter Kopietz

We include spontaneous symmetry breaking into the functional renormalization group (RG) equations for the irreducible vertices of Ginzburg-Landau theories by augmenting these equations by a flow equation for the order parameter, which is determined from the requirement that at each RG step the vertex with one external leg vanishes identically. Using this str

Karin Halupczok

For A,epsilon>0 and any sufficiently large odd n we show that for almost all k up to n^{1/5-epsilon} there exists a representation n=p1+p2+p3 with primes in residue classes b1,b2,b3 mod k for almost all admissible triplets b1,b2,b3 of reduced residues mod k.

Francesco Caporale, Alessandro Papa, Agustin Sabio Vera

The use of the BFKL kernel improved by the inclusion of subleading terms generated by renormalization group (RG) analysis has been suggested to cure the instabilities in the behavior of the BFKL Green's function in the next-to-leading approximation (NLA). We test the performance of a RG-improved kernel in the determination of the amplitude of a physical

Christian Genest, Johan Segers

Consider a continuous random pair $(X,Y)$ whose dependence is characterized by an extreme-value copula with Pickands dependence function $A$. When the marginal distributions of $X$ and $Y$ are known, several consistent estimators of $A$ are available. Most of them are variants of the estimators due to Pickands [Bull. Inst. Internat. Statist. 49 (1981) 859--8

B. R. Barrett, B. G. Giraud, B. K. Jennings, N. P. Toberg

Sequences of experimental ground-state energies for both odd and even $A$ are mapped onto concave patterns cured from convexities due to pairing and/or shell effects. The same patterns, completed by a list of excitation energies, give numerical estimates of the grand potential $Ω(β,μ)$ for a mixture of nuclei at low or moderate temperatures $T=β^{-1}$ and at

F. F. Fanchini, R. d. J. Napolitano

We show that continuous dynamical decoupling can protect a two-qubit entangled state from sudden death at finite temperature due to uncorrelated dephasing, bit flipping, and dissipation. We consider a situation where an entangled state shared between two non-interacting qubits is initially prepared and left evolve under the environmental perturbations and th

Miquel Montero, Jaume Masoliver

The usual development of the continuous time random walk (CTRW) assumes that jumps and time intervals are a two-dimensional set of independent and identically distributed random variables. In this paper we address the theoretical setting of non-independent CTRW's where consecutive jumps and/or time intervals are correlated. An exact solution to the probl

Michal Ochman, Robert Szafron, Marek Zralek

General quantum mechanical states of neutrinos produced by mechanisms outside the Standard Model are discussed. The neutrino state is described by the Maki-Nakagawa-Sakata-Pontecorvo unitary mixing matrix only in the case of relativistic neutrinos and Standard Model left-handed charge current interaction. The problem of Wigner spin rotation caused by Lorentz

Ginestra Bianconi, Natali Gulbahce, Adilson E. Motter

Previous work on undirected small-world networks established the paradigm that locally structured networks tend to have high density of short loops. On the other hand, many realistic networks are directed. Here we investigate the local organization of directed networks and find, surprisingly, that real networks often have very few short loops as compared to

COMPASS Collaboration, M. Alekseev

The semi-inclusive difference asymmetry A^{h^{+}-h^{-}} for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002-2004 using a 160 GeV polarised muon beam scattered off a large polarised ^6LiD target and cover the range 0.006 < x < 0.7 and 1 < Q^2 < 100 (GeV/c)^2. In leading order QCD (LO) t

Matthias R. Gaberdiel

We argue that the existence of a modular differential equation implies that a certain vector vanishes in Zhu&#39;s C2 quotient space, and we check this assertion in numerous examples. If this connection is true in general, it would imply that the recently conjectured extremal self-dual conformal field theories at c=24 k cannot exist for k\geq 42.

Rabindra N. Mohapatra, Michael Ratz

We discuss the results of a search for anomaly free Abelian Z_N discrete symmetries that lead to automatic R-parity conservation and prevents dangerous higher-dimensional proton decay operators in simple extensions of the minimal supersymmetric extension of the standard model (MSSM) based on the left-right symmetric group, the Pati-Salam group and SO(10). We

Jeremy Metz, Christian Schoen, Almut Beige

We describe a measurement-based state preparation scheme for the efficient build up of cluster states in atom-cavity systems. As in a recent proposal for the generation of maximally entangled atom pairs [Metz et al., Phys. Rev. Lett. 97, 040503 (2006)], we use an electron shelving technique to avoid the necessity for the detection of single photons. Instead,

Y. Hashimoto, H. Munekata

Precession of magnetization induced by pulsed optical excitation is observed in a ferromagnetic semiconductor (Ga,Mn)As by time-resolved magneto-optical measurements. It appears as complicated oscillations of polarization plane of linearly-polarized probe pulses, but is reproduced by gyromagnetic theory incorporating an impulsive change in an effective magne

Xia-Ji Liu, Hui Hu, Peter D. Drummond

We present a systematic study of quantum phases in a one-dimensional spin-polarized Fermi gas. Three comparative theoretical methods are used to explore the phase diagram at zero temperature: the mean-field theory with either an order parameter in a single-plane-wave form or a self-consistently determined order parameter using the Bogoliubov-de Gennes equati

Andrew J. Fox, Cédric Ledoux, Patrick Petitjean, Raghunathan Srianand

We present a study of C IV absorption in a sample of 63 damped Lyman-alpha (DLA) systems and 11 sub-DLAs in the redshift range 1.75<z_abs<3.61, using a dataset of high-resolution (6.6 km/s FWHM), high signal-to-noise VLT/UVES spectra. Narrow and broad C IV absorption line components indicate the presence of both warm, photoionized and hot, collisionally ioni

Reynier Peletier

Historically, galactic bulges are thought to be elliptical galaxy-like objects sitting in the middle of a generally larger disk. There are, however, more and more claims that some bulges are much more similar to disks. John Kormendy has named these bulges pseudo-bulges. In this paper I discuss some recent integral field spectroscopy of the SAURON collaborati

Hao Wei, Rong-Gen Cai

A new dark energy model, named &#34;agegraphic dark energy&#34;, has been proposed recently, based on the so-called Károlyházy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureles

A. Abada, C. Biggio, F. Bonnet, M. B. Gavela

While all models of Majorana neutrino masses lead to the same dimension five effective operator, which does not conserve lepton number, the dimension six operators induced at low energies conserve lepton number and differ depending on the high energy model of new physics. We derive the low-energy dimension six operators which are characteristic of generic Se

Daekyoung Kang, Taewon Kim, Jungil Lee, Chaehyun Yu

Based on the NRQCD factorization formalism, we calculate the inclusive charm production rate in Upsilon(nS) decay at leading order in the strong coupling constant alpha_s and the relative velocity v of the b quark in the quarkonium rest frame. The branching fractions for Upsilon(nS) to charm for n=1, 2, and 3 are all around 7-9%. About 60% of the branching f

Rong-Gen Cai

Quantum mechanics together with general relativity leads to the Károlyházy relation and a corresponding energy density of quantum fluctuations of space-time. Based on the energy density we propose a dark energy model, in which the age of the universe is introduced as the length measure. This dark energy is consistent with astronomical data if the unique nume

H. Lange, P. E. Newstead

Final version to appear in Archiv der Mathematik.

Dmitry Jakobson, Dan Mangoubi

We give upper and lower bounds on the volume of a tubular neighborhood of the nodal set of an eigenfunction of the Laplacian on a real analytic closed Riemannian manifold M. As an application we consider the question of approximating points on M by nodal sets, and explore analogy with approximation by rational numbers.

T. L. Boyadjiev, O. Yu. Andreeva, E. G. Semerdjieva, Yu. M. Shukrinov

Critical curves &#34;critical current - external magnetic field&#34; of long Josephson junctions with inhomogeneity and variable width are studied. We demonstrate the existence of the regions of magnetic field where some fluxon states are stable only, if the external current through the junction is different from zero. Position and size of such regions depen

James Allen Fill

A well-known theorem usually attributed to Keilson states that, for an irreducible continuous-time birth-and-death chain on the nonnegative integers and any d, the passage time from state 0 to state d is distributed as a sum of d independent exponential random variables. Until now, no probabilistic proof of the theorem has been known. In this paper we use th

Philip V. Fellman, Jonathan P. Clemens, Roxana Wright, Jonathan Vos Post

Over a period of approximately five years, Pankaj Ghemawat of Harvard Business School and Daniel Levinthal of the Wharton School have been working on a detailed simulation (producing approximately a million fitness landscape graphs) in order to determine optimal patterns of decision-making for corporations. In 2006, we adapted this study, combining it with o

Jun-ichi Nakashima, David Fong, Tatsuhiko Hasegawa, Naomi Hirano

We report on the results of a Submillimeter Array interferometric observation of the proto-planetary nebula CRL 618 in the 12CO J=6-5 line. With the new capability of SMA enabling us to use two receivers at a time, we also observed simultaneously in the 12CO J=2-1 and 13CO J=2-1 lines. The 12CO J=6-5 and 13CO J=2-1 lines were first interferometrically observ

Hong Huang

In this note we present some gradient estimates for the diffusion equation $\partial_t u=Δu-\nabla ϕ\cdot \nabla u $ on Riemannian manifolds, where $ϕ$ is a C^2 function, which generalize estimates of R. Hamilton&#39;s and Qi S. Zhang&#39;s on the heat equation.

Rodrigo Aros, Mauricio Romo

A class of p-brane solutions for supersymmetric gravity theories with negative cosmological constant are proposed and analyzed. The solutions are purely bosonic and contain a worldsheet and a transverse section. The classification relays on the number of intrinsic Killing spinors on the worldsheet and the transverse section. A explicit discussion of the clas

D. A. Ross, M. Wiebusch

We report on a calculation of the effects of supersymmetry on the cross-section for top-antitop production at LHC. A numerical study is carried out for the ten benchmarks of the Snowmass accord. It is found that the higher order effects involving supersymmetric particles in internal loops can be as high as 6%, both for the cross-section and the (parity even)

V. S. Beskin, S. A. Eliseeva

We explore the possibilities for detecting pulsars that have ceased to radiate in the radio band. We consider two models: the model with hindered particle escape from the pulsar surface (first suggested by Ruderman and Sutherland 1975) and the model with free particle escape (Arons 1981; Mestel 1999). In the model with hindered particle escape, the number of

Russ Abbott

Can there be independent higher level laws of nature if everything is reducible to the fundamental laws of physics? The computer science notion of level of abstraction explains why there can -- illustrating how computational thinking can solve one of philosophy's most vexing problems.

Andrzej Madrecki

We give a short probabilistic (a Brownian motion) proof of the Riemann hypothesis based on some surprising, unexpected and deep algebraic conjecture (MAC in short) concerning the relation between the Riemann zeta $ξ$ and a trivial zeta $ζ_{t}$. That algebraic conjecture was firstly discovered and formulated in [MA]

Anh-Thu Le, Toru Morishita, C. D. Lin

We demonstrate a simple method to improve the Lewenstein model for the description of high-order harmonic generation (HHG). It is shown that HHG spectra can be expressed as the product of a returning electron wave packet and the photo-recombination cross sections, where the former can be extracted from the Lewenstein model. By replacing plane waves with scat

Philip S. Amanik, Gail C. McLaughlin

We analyze the prospect of measuring the neutron form factor of a nucleus through the detection of neutrino-nucleus coherent elastic scattering. We predict numbers of events in a liquid noble nuclear recoil detector at a stopped pion neutrino source. We discuss the precision required to distinguish between different theoretical models for the form factor.

V. Desai, L. Armus, H. W. W. Spoon, V. Charmandaris

We explore the relationships between the Polycyclic Aromatic Hydrocarbon (PAH) feature strengths, mid-infrared continuum luminosities, far-infrared spectral slopes, optical spectroscopic classifications, and silicate optical depths within a sample of 107 ULIRGs observed with the Infrared Spectrograph on the Spitzer Space Telescope. The detected 6.2 micron PA

Varlei Rodrigues, Fernando Sato, Douglas S. Galvao, Daniel Ugarte

We report high resolution transmission electron microscopy and ab initio calculation results for the defect formation in Pt nanocontacts (NCs). Our results show that there is a size limit to the existence of twins (extended structural defects). Defects are always present but blocked away from the tip axes. The twins may act as scattering plane, influencing c

Erasmo Ferreira

We extend the use of derivative dispersion relations to the study of slopes of the real and imaginary amplitudes in pp and p-pbar elastic scattering. The new relations are tested against the solutions for the amplitudes obtained in the analysis of the high energy data. Extensions beyond the forward direction are investigated.

M. E. Schwartz, T. H. Solomon

We present experiments on the behavior of reaction fronts in ordered and disordered cellular flows with imposed winds. Fronts in a chain of alternating vortices are found to freeze (pin to the separatrix) for a wide range of imposed winds that grows nonlinearly with the characteristic strength of the underlying vorticity. Experiments in spatially-disordered

Edith Adan-Bante

Let G be a finite p-group, for some prime p, and $ψ, θ\in \Irr(G)$ be irreducible complex characters of G. It has been proved that if, in addition, $ψ,θ$ are faithful characters, then the product $ψθ$ is a multiple of an irreducible or it is the nontrivial linear combination of at least $\frac{p+1}{2}$ distinct irreducible characters of G. We show that if we

Steve Dawson, James E. Rhoads, Sangeeta Malhotra, Daniel Stern

We present a catalog of 59 z=4.5 Lyman alpha emitting galaxies spectroscopically confirmed in a campaign of Keck/DEIMOS follow-up observations to candidates selected in the Large Area Lyman Alpha (LALA) narrow-band imaging survey. We targeted 97 candidates for spectroscopic follow-up; by accounting for the variety of conditions under which we performed spect

W. J. H. Leyland, R. T. Harley, M. Henini, D. Taylor

Optical pump-probe measurements of spin-dynamics at temperatures down to 1.5K are described for a series of (001)-oriented GaAs/AlGaAs quantum well samples containing high mobility two-dimensional electron gases (2DEGs). For well widths ranging from 5 nm to 20 nm and 2DEG sheet densities from 1.75x1011cm-2 to 3.5x1011cm-2 the evolution of a small injected sp

A. R. Abate, D. J. Durian

We introduce topological methods for quantifying spatially heterogeneous dynamics, and use these tools to analyze particle-tracking data for a quasi-two-dimensional granular system of air-fluidized beads on approach to jamming. In particular we define two overlap order parameters, which quantify the correlation between particle configurations at different ti

K. S. Burch, Elbert E. M. Chia, D. Talbayev, B. C. Sales

We explore the ultra-fast optical response of Yb_{14}MnSb_{11}, providing further evidence that this Zintl compound is the first ferromagnetic, under-screened Kondo lattice. These experiments also provide the first demonstration of coupling between an optical phonon mode and the Kondo effect.

Thaisa Storchi-Bergmann, Oli L. Dors, Rogemar A. Riffel, Kambiz Fathi

We report the discovery of gas streaming motions along nuclear spiral arms towards the LINER nucleus of the galaxy NGC 6951. The observations, obtained using the GMOS integral field spectrograph on the Gemini North telescope, yielded maps of the flux distributions and gas kinematics in the Halpha, [NII]6584 and [SII]6717,31 emission lines of the inner 7x5 ar

Razvan Tudor Radulescu

The multiple worlds of genetically manipulated laboratory organisms such as transgenic mice or worms with certain gene mutations are somewhat reminiscent of parallel worlds in quantum mechanics. So are various models of aging tested in such organisms. In this context, the tumor suppressor p53 has been found to either accelerate or delay aging, the latter, fo