November 2005 arXiv papers — page 25

Z. Yang, X. Sun, Y. Gao, S. Chen

The effects of intensity interferometry (HBT), which are mainly reflected by the measured momentum correlations, have been fully discussed since 1950's. The analogous momentum correlations between identical fermions are however less argued. Besides the fermion statistics, the momentum correlations between identical fermions are also determined by some ot

Berndt Müller

This is a review of the latest developments in the theory of superdense nuclear matter, formed in relativistic heavy ion collisions or in the core of collapsed stars, as they were reported and discussed at the Quark Matter 2005 conference in Budapest (Hungary).

STAR Collaboration

We present the centrality dependent measurement of multiplicity and pseudorapidity distributions of charged particles and photons in Au + Au collisions at sqrt{s_NN} = 62.4 GeV. The charged particles and photons are measured in the pseudorapidity region 2.9 < eta < 3.9 and 2.3 < eta < 3.7, respectively. We have studied the scaling of particle production with

G. M. Zaslavsky, M. Edelman

We consider a perturbation of the Anosov-type system, which leads to the appearance of a hierarchical set of islands-around-islands. We demonstrate by simulation that the boundaries of the islands are sticky to trajectories. This phenomenon leads to the distribution of Poincare recurrences with power-like tails in contrast to the exponential distribution in

Paolo Lorenzoni, Simone Paleari

We show the relevance of the dispersive analogue of the shock waves in the FPU dynamics. In particular we give strict numerical evidences that metastable states emerging from low frequency initial excitations, are indeed constituted by dispersive shock waves travelling through the chain. Relevant characteristics of the metastable states, such as their freque

P. R. Gordoa, A. Pickering, M. Senthilvelan

We investigate the Painleve analysis for a (2+1) dimensional Camassa-Holm equation. Our results show that it admits only weak Painleve expansions. This then confirms the limitations of the Painleve test as a test for complete integrability when applied to non-semilinear partial differential equations.

Peter Horvai

We exploit the analogy between dynamics of inertial particle pair separation in a random-in-time flow and the Anderson model of a quantum particle on the line in a spatially random real-valued potential. Thereby we get an exact formula for the Lyapunov exponent of pair separation in a special case, and we are able to generalize the class of solvable models s

A. G. Ramm

Consider the equation $-\ve^2Δu_\ve+q(x)u_\ve=f(u_\ve)$ in $\R^3$, $|u(\infty)|<\infty$, $\ve=const>0$. Under what assumptions on $q(x)$ and $f(u)$ can one prove that the solution $u_\ve$ exists and $\lim_{\ve\to 0} u_\ve=u(x)$, where $u(x)$ solves the limiting problem $q(x)u=f(u)$? These are the questions discussed in the paper.

Cristian Cobeli, Alexandru Zaharescu

The spacing distribution between Farey points has drawn attention in recent years. It was found that the gaps $γ_{j+1}-γ_j$ between consecutive elements of the Farey sequence produce, as $Q\to\infty$, a limiting measure. Numerical computations suggest that for any $d\ge 2$, the gaps $γ_{j+d}-γ_j$ also produce a limiting measure whose support is distinguished

Cristian Cobeli, Alexandru Zaharescu

Let $F_Q$ be the Farey sequence of order $Q$ and let $F_{Q,o}$ and $F_{Q,e}$ be the set of those Farey fractions of order $Q$ with odd, respectively even denominators. A fundamental property of $F_Q$ says that the sum of denominators of any pair of neighbor fractions is always greater than $Q$. This property fails for $F_{Q,o}$ and for $F_{Q,e}$. The local d

Y. Zou, I. G. Kevrekidis, D. Armbruster

The computer-assisted modeling of re-entrant production lines, and, in particular, simulation scalability, is attracting a lot of attention due to the importance of such lines in semiconductor manufacturing. Re-entrant flows lead to competition for processing capacity among the items produced, which significantly impacts their throughput time (TPT). Such pro

A. G. Ramm

It is proved that the measurement of the acoustic pressure on the ear membrane allows one to determine the shape of the ear $ uniquely.

Cristian Cobeli, Alexandru Zaharescu

Let $F_Q$ be the set of Farey fractions of order $Q$. Given the integers $\d\ge 2$ and $0\le \c \le \d-1$, let $F_Q(c,d)$ be the subset of $F_Q$ of those fractions whose denominators are $\equiv c \pmod d$, arranged in ascending order. The problem we address here is to show that as $Q\to\infty$, there exists a limit probability measuring the distribution of

Cristian Cobeli, Alexandru Zaharescu

Our purpose is to give an account of the $r$-tuple problem on the increasing sequence of reduced fractions having denominators bounded by a certain size and belonging to a fixed real interval. We show that when the size grows to infinity, the proportion of the $r$-tuples of consecutive denominators with components in certain apriori fixed arithmetic progress

Eugenio A. M. Rocha, Delfim F. M. Torres

We obtain a method to compute effective first integrals by combining Noether&#39;s principle with the Kozlov-Kolesnikov integrability theorem. A sufficient condition for the integrability by quadratures of optimal control problems with controls taking values on open sets is obtained. We illustrate our approach on some problems taken from the literature. An a

A. G. Ramm

Let $A=A^*$ be a linear operator in a Hilbert space $H$. Assume that equation $Au=f \quad (1)$ is solvable, not necessarily uniquely, and $y$ is its minimal-norm solution. Assume that problem (1) is ill-posed. Let $f_\d$, $||f-f_d||\leq \d$, be noisy data, which are given, while $f$ is not known. Variational regularization of problem (1) leads to an equation

Jan Stienstra

This text is based on lectures by the author in the Summer School `Algebraic Geometry and Hypergeometric Functions&#39; in Istanbul in June 2005. It gives a review of some of the basic aspects of the theory of hypergeometric structures of Gelfand, Kapranov and Zelevinsky, including Differential Equations, Integrals and Series, with emphasis on the latter. Th

Ruslan Sharipov

Spinor fields depending on tensor fields and other spinor fields are considered. The concept of extended spinor fields is introduced and the theory of differentiation for such fields is developed.

Eugenio A. M. Rocha, Delfim F. M. Torres

The fundamental problem of calculus of variations is considered when solutions are differentiable curves on locally convex spaces. Such problems admit an extension of the Euler-Lagrange equations [Orlov 2002] for continuously normally differentiable Lagrangians. Here, we formulate a Legendre condition and an extension of the classical theorem of Emmy Noether

Dimitri Petritis

We present the formalism of sequential and asynchronous processes defined in terms of random or quantum grammars and argue that these processes have relevance in genomics. To make the article accessible to the non-mathematicians, we keep the mathematical exposition as elementary as possible, focusing on some general ideas behind the formalism and stating the

K. Ardakov, K. A. Brown

This is a survey of the known properties of Iwasawa algebras, which are completed group rings of compact p-adic analytic groups with coefficients the ring Zp of p-adic integers or the field Fp of p elements. A number of open questions are also stated.

Haisheng Li

A notion of vertex bialgebra and a notion of module nonlocal vertex algebra for a vertex bialgebra are studied and then a smash product construction of nonlocal vertex algebras is presented. For every nonlocal vertex algebra $V$ satisfying a suitable condition, a canonical bialgebra $B(V)$ is constructed such that primitive elements of $B(V)$ are essentially

Hajime Tsuji

Generalizing the recent result of Berndtsson, we prove the Nakano semipositivity of the direct image of relative pluricanonical systems and the direct image of relative adjoint (singular) hermitian line bundle with semipositive curvature. This gives a new proof of Kawamata&#39;s theorem on the semipositivity of the direct image of relative pluricanonical sys

Yuuki Tadokoro

We give a explicit computation of the pointed harmonic volumes of hyperelliptic curves with Weierstrass base points, which are paraphrased into a combinatorial formula.

Bebe Prunaru

A family $\{T_j\}_{j\in J}$ of commuting Hilbert space operators is said to be a spherical isometry if $\sum_{j\in J}T^*_jT_j=1$ in the weak operator topology. We show that every commuting family $\Cal F$ of spherical isometries has a commuting normal extension $\hat{\Cal F}$. Moreover, if $\hat{\Cal F}$ is minimal, then there exists a natural short exact se

Sandro Mattarei

In 1988 Garcia and Voloch proved the upper bound 4n^{4/3}(p-1)^{2/3} for the number of solutions over a prime finite field F_p of the Fermat equation x^n+y^n=a, where a \in F_p^* and n \ge 2 is a divisor of p-1 such that (n-1/2)^4 \ge p-1. This is better than Weil&#39;s bound p+1+(n-1)(n-2)p^{1/2} in the stated range. By refining Garcia and Voloch&#39;s proo

Alain Connes, Michel Dubois-Violette

This paper contains detailed proofs of our results on the moduli space and the structure of noncommutative 3-spheres. We develop the notion of central quadratic form for quadratic algebras, and a general theory which creates a bridge between noncommutative differential geometry and its purely algebraic counterpart. It allows to construct a morphism from an i

Paavo Salminen, Marc Yor

In this note, with the help of the boundary classification of diffusions, we derive a criterion of the convergence of perpetual integral functionals of transient real-valued diffusions. In the particular case of transient Bessel processes, we note that this criterion agrees with the one obtained via Jeulin&#39;s convergence lemma.

Alex D. Gottlieb

Determinantal point processes on a measure space X whose kernels represent trace class Hermitian operators on L^2(X) are associated to &#34;quasifree&#34; density operators on the Fock space over L^2(X).

Shujun Li

This paper studies so-called &#34;null polynomials modulo m&#34;, i.e., polynomials with integer coefficients that satisfy f(x)=0 (mod m) for any integer x. The study on null polynomials is helpful to reduce congruences of higher degrees modulo m and to enumerate equivalent polynomial functions modulo m, i.e., functions over Z_m={0, ..., m-1} generated by in

Peter Cholak, Joseph Miller, Noam Greenberg

We explore the interaction between Lebesgue measure and dominating functions. We show, via both a priority construction and a forcing construction, that there is a function of incomplete degree that dominates almost all degrees. This answers a question of Dobrinen and Simpson, who showed that such functions are related to the proof-theoretic strength of the

Dmitry A. Berdinsky, Iskander A. Taimanov

We derive the Weierstrass (or spinor) representation for surfaces in three-dimensional Lie groups Nil, \tilde{SL}_2, and Sol with Thurston&#39;s geometries and establish the generating equations for minimal surfaces in these groups. By using the spectral properties of the corresponding Dirac operators we find analogs of the Willmore functional for surfaces i

Paul Levy

Let $G$ be a reductive group over a field $k$ of characteristic $\neq 2$, let ${\mathfrak g}=\Lie(G)$, let $θ$ be an involutive automorphism of $G$ and let ${\mathfrak g}={\mathfrak k}\oplus{\mathfrak p}$ be the associated symmetric space decomposition. For the case of a ground field of characteristic zero, the action of the isotropy group $G^θ$ on ${\mathfr

William Y. C. Chen, Eva Y. P. Deng, Rosena R. X. Du, Richard P. Stanley

We present results on the enumeration of crossings and nestings for matchings and set partitions. Using a bijection between partitions and vacillating tableaux, we show that if we fix the sets of minimal block elements and maximal block elements, the crossing number and the nesting number of partitions have a symmetric joint distribution. It follows that the

Intan Muchtadi-Alamsyah

By Rickard&#39;s work, two rings are derived equivalent if there is a tilting complex, constructed from projective modules over the first ring such that the second ring is the endomorphism ring of this tilting complex. In this work I describe, under some conditions, the homomorphism space in the derived category between two complexes as iterated pull-back of

Ryan Budney

A non-singular sesquilinear form is constructed that is preserved by the Lawrence-Krammer representation. It is shown that if the polynomial variables q and t of the Lawrence-Krammer representation are chosen to be appropriate algebraically independant unit complex numbers, then the form is negative-definite Hermitian. Since unitary matrices diagonalize, the

Marek Wieckowski

This article describes a method for calculating S-matrix elements using Hamiltonians obtained in the renormalization group procedure for effective particles. It is shown that the scattering amplitudes obtained using a canonical Hamiltonian $H^Δ$ with counterterms are the same as those obtained using a renormalized Hamiltonian for effective particles, $H_λ$.

V. Bardek, S Meljanac

It is shown that a method for constructing exact multi-solitonic solutions of the coupled BPS equations in the duality-based generalization of the hermitean matrix model, which was put forward in a recent paper, is not correct.

Roberto Zucchini

BiKaehler geometry is characterized by a Riemannian metric g_{ab} and two covariantly constant generally non commuting complex structures K_+^a_b, K_-^a_b, with respect to which g_{ab} is Hermitian. It is a particular case of the biHermitian geometry of Gates, Hull and Roceck, the most general sigma model target space geometry allowing for (2,2) world sheet

M. C. B. Abdalla, A. A. Bytsenko, M. E. X. Guimaraes

There is a remarkable connection between the number of quantum states of conformal theories and the sequence of dimensions of Lie algebras. In this paper, we explore this connection by computing the asymptotic expansion of the elliptic genus and the microscopic entropy of black holes associated with (supersymmetric) sigma models. The new features of these re

Zen Wei

In the spirit of Black Hole Complementary Principle, we have found the noncommutative membrane of Scharzchild Black Holes. In this paper we extend our results to Kerr Black Hole and see the same story. Also we make a conjecture that spacetimes is noncommutative on the stretched membrane of the more general Kerr-Newman Black Hole.

Thomas Schwetz, Walter Winter

We propose that reactor experiments could be used to constrain the environment dependence of neutrino mass and mixing parameters, which could be induced due to an acceleron coupling to matter fields. There are several short-baseline reactor experiment projects with different fractions of air and earth matter along the neutrino path. Moreover, the short basel

Ivan Schmidt

The physics of hadron single transverse spin asymmetries is discussed. Possible measurements of both the quark and gluon Sivers functions are proposed.

Ivan Schmidt

Shadowing and antishadowing of the electromagnetic nuclear structure functions are produced by the coherence of multiscattering quark nuclear processes. This picture leads to substantially different antishadowing for charged and neutral current processes, particularly in anti-neutrino reactions, thus affecting the extraction of the weak-mixing angle $\sin^2θ

Pran Nath, Raza M. Syed

Higgs multiplet in the vector-spinor representations of SO(10), i.e., the $144+\bar{144}$ multiplet can break the SO(10) gauge symmetry spontaneously in one step down to the Standard Model gauge group symmetry $SU(3)_C\times SU(2)_L\times U(1)_Y$ and a recent analysis has used such vector-spinors for building a new class of SO(10) grand unification models (h

F. Giacosa, Th. Gutsche, V. E. Lyubovitskij, Amand Faessler

The strong and electromagnetic decays of the ground-state tensor mesons are studied in an effective field approach. A fit to the well-known experimental data is performed. The decay ratios of the tensor glueball are evaluated and possible candidates are discussed.

Andrea Bianconi

A short summary of results of recent simulations of (un)polarized Drell-Yan experiments is presented here. Dilepton production in $pp$, $\bar{p}p$, $π^-p$ and $π^+p$ scattering is considered, for several kinematics corresponding to interesting regions for experiments at GSI, CERN-Compass and RHIC. A table of integrated cross sections, and a set of estimated

Karol Kolodziej, Tomasz Westwanski

We discuss the standard model factorizable radiative corrections to e+e- -> mu+ mu- b bar_b, which is one of the best detection channels of the low mass Higgs boson produced through the Higgsstrahlung mechanism at a linear collider. The discussion includes the leading virtual and real quantum electrodynamics corrections due to the initial state radiation, th

S. D. Katz

Recent results on the equation of state from lattice QCD are reviewed. The lattice technique and previous results are shortly discussed. New results for physical quark masses and two sets of lattice spacings are presented. The pressure, energy density, entropy density, speed of sound and quark number susceptibilities are determined.

Alejandro Rivero

The GUT value of Weinberg&#39;s angle is also the value that minimises the total square matrix elements of $Z^0$ decay, independently of any GUT consideration, and thus the one that maximises the neutrino branching ratio against total width. We review the proof of this result and some related facts.

Kiwoon Choi

In string compactification preserving N=1 SUSY, moduli fields are plausible candidates for the messenger of SUSY breaking at low energy scales. In a scenario that moduli-mediated SUSY breaking is significant, the pattern of soft SUSY breaking terms depends crucially on how the light moduli with mass m \lesssim O(8π^2 m_{3/2}) are stabilized. We discuss the c

Quentin Mason, Howard D. Trottier, Ron Horgan, Christine T. H. Davies

Three-flavor lattice QCD simulations and two-loop perturbation theory are used to make the most precise determination to date of the strange-, up-, and down-quark masses, $m_s$, $m_u$, and $m_d$, respectively. Perturbative matching is required in order to connect the lattice-regularized bare- quark masses to the masses as defined in the \msbar scheme, and th

Eun-Joo Ahn, Marco Cavaglia

We present a comprehensive study of TeV black hole events in Earth&#39;s atmosphere originated by cosmic rays of very high energy. An advanced fortran Monte Carlo code is developed and used to simulate black hole extensive air showers from ultrahigh-energy neutrino-nucleon interactions. We investigate the characteristics of these events, compare the black ho

Raju Venugopalan

Multi-particle production in QCD is dominated by higher twist contributions. The operator product expansion is not very effective here because the number of relevant operators grow rapidly with increasing twist. The Color Glass Condensate (CGC) provides a framework in QCD to systematically discuss &#34;classical&#34; (multiple scattering) and &#34;quantum&#3

T. Banks

I present a low energy Lagrangian implementing the idea of Cosmological SUSY breaking (CSB). The model predicts ${\rm tan}β\sim 1$, and incorporates a new mechanism for breaking of $SU(2)\times U(1)$. The Higgs mass is determined by new physics and can evade the bounds of the MSSM. The model resolves the CP and flavor problems of SUSY. The up quark mass is n

A. Mikovic

It is known that the Einstein-Hilbert action with a positive cosmological constant can be represented as a perturbation of the SO(4,1) BF theory by a symmetry-breaking term quadratic in the B field. Introducing fermionic matter generates additional terms in the action which are polynomial in the tetrads and the spin connection. We describe how to construct t

Robert M. Wald

This Resource Letter provides some guidance on issues that arise in teaching general relativity at both the undergraduate and graduate levels. Particular emphasis is placed on strategies for presenting the mathematical material needed for the formulation of general relativity.

Leland Smith, Muthukumar Thirunavukkarasu, Srinidhi Varadarajan, Naren Ramakrishnan

Current directions in network routing research have not kept pace with the latest developments in network architectures, such as peer-to-peer networks, sensor networks, ad-hoc wireless networks, and overlay networks. A common characteristic among all of these new technologies is the presence of highly dynamic network topologies. Currently deployed single-pat

Gilson A. Giraldi, Antonio A. F. Oliveira, Leonardo Carvalho

Cellular Automata are discrete dynamical systems that evolve following simple and local rules. Despite of its local simplicity, knowledge discovery in CA is a NP problem. This is the main motivation for using data mining techniques for CA study. The Principal Component Analysis (PCA) is a useful tool for data mining because it provides a compact and optimal

Xiangyong Zeng, Qingchong Liu, Lei Hu

In this paper new binary sequence families $\mathcal{F}^k$ of period $2^n-1$ are constructed for even $n$ and any $k$ with ${\rm gcd}(k,n)=2$ if $n/2$ is odd or ${\rm gcd}(k,n)=1$ if $n/2$ is even. The distribution of their correlation values is completely determined. These families have maximum correlation $2^{n/2+1}+1$ and family size $2^{3n/2}+2^{n/2}$ fo

Marco Cuturi, Kenji Fukumizu

We present in this work a new methodology to design kernels on data which is structured with smaller components, such as text, images or sequences. This methodology is a template procedure which can be applied on most kernels on measures and takes advantage of a more detailed &#34;bag of components&#34; representation of the objects. To obtain such a detaile

D. Wang, M. D. Hossain, Z. Salman, D. Arseneau

$β$-NMR of isolated $^8$Li has been investigated in the normal state of 2H-NbSe$_2$. In a high magnetic field of 3T a single resonance is observed with a Gaussian line width of 3.5 kHz. The line shape varies weakly as function of magnetic field and temperature but has a strong orientation dependence. The nuclear electric quadrupole splitting is unresolved im

Z. Salman, R. F. Kiefl, K. H. Chow, W. A. MacFarlane

Beta-detected nuclear quadrupole resonances (\bnqr) at zero field are observed using a beam of low energy highly polarized radioactive \nuc{8}{Li}$^+$. The resonances were detected in SrTiO$_3$, Al$_2$O$_3$ and Sr$_2$RuO$_4$ single crystals by monitoring the beta-decay anisotropy as a function of a small audio frequency magnetic field. The resonances show cl

Yaniv Avizrats, Joshua Feinberg, Shmuel Fishman

We apply a probabilistic approach to study the computational complexity of analog computers which solve linear programming problems. We analyze numerically various ensembles of linear programming problems and obtain, for each of these ensembles, the probability distribution functions of certain quantities which measure the computational complexity, known as

Alexei Kolezhuk, Subir Sachdev

In the O(3) sigma-model description of gapped spin systems, S=1 magnons can only decay into three lower energy magnons. We argue that the symmetry of the quantum spin Hamiltonian often allows decay into two magnons, and compute this decay rate in model systems. Two magnon decay is present in Haldane gap S=1 spin chains, even though it cannot be induced by an

Serge Shpyrko, Vladimir M. Sysoev

The reversible reactions like A+B <-> C in the many-component diffusive system affect the diffusive properties of the constituents. The effective conjugation of irreversible processes of different dimensionality takes place due to the stationarity in the system and can lead to essential increase of the resulting diffusive fluxes. The exact equations for the

Arti Garg, H. R. Krishnamurthy, Mohit Randeria

We analyze the effects of the on-site Coulomb repulsion U on a band insulator using dynamical mean field theory (DMFT). We find the surprising result that the gap is suppressed to zero at a critical Uc1 and remains zero within a metallic phase. At a larger Uc2 there is a second transition from the metal to a Mott insulator, in which the gap increases with in

G. Ramon, U. Mizrahi, N. Akopian, S. Braitbart

The emission properties of single quantum dots in planar microcavities are studied experimentally and theoretically. Fivefold Enhanced spontaneous emission outside the microcavity is found for dots in resonance with the cavity mode, relative to detuned dots, while their radiative lifetime is only marginally decreased. Using high power excitation we obtain th

Y. Ahmadian, I. L. Aleiner

We study the effect of spin-orbit scattering on the statistics of the conductance of a quantum dot for Coulomb blockade peaks and valleys. We find the distribution function of the peak heights for strong spin-orbit scattering in the presence and absence of time reversal symmetry. We find that the application of a magnetic field suppresses the average peak he

Pawel Buczek, Janusz Wolny

We study decorated one-dimensional quasicrystal obtained by a non-standard projection of a part of two-dimensional lattice. We focus on the impact of varying relative positions of decorated sites. First, we give general expression for the structure factor. Subsequently we analyze an example of extinction rule.

S Condamin, O. Benichou, M. Moreau

We present a novel computational method of first-passage times between a starting site and a target site of regular bounded lattices. We derive accurate expressions for all the moments of this first-passage time, validated by numerical simulations. Their range of validity is discussed. We also consider the case of a starting site and two targets. In addition

Angel J. Garcia-Adeva

A new family of two- and three-dimensional photonic crystals with the symmetry of the kagome and pyrochlore lattices that exhibit interesting photonic band structures are reported. From large complete photonic band gaps in three dimensions to enormous partial gaps in two dimensions for certain polarizations occurring at feature sizes that make these lattice

Frithjof B. Anders, Thomas Pruschke

The recently reported unusual behavior of the static and dynamical magnetic susceptibility as well as the specific heat in Ce$_{1-x}$La$_{x}$Ni$_{9}$Ge$_4$ has raised the question of a possible non-Fermi liquid ground state in this material. We argue that for a consistent physical picture the crystal field splitting of two low lying magnetic doublets of the

M. Gorska, A. Lusakowski, A. Jedrzejczak, Z. Golacki

The temperature dependence of the magnetic specific heat has been studied experimentally and theoretically in the semimagnetic semiconductor Pb_{1-x}Eu_{x}Te for x=0.027 and x=0.073, over the temperature range from 0.5 K to 10 K, in magnetic fields up to 2 T. There was a maximum in the magnetic specific heat between 1 and 3 K even in zero and low magnetic fi

K. Balzer, C. Nölle, M. Bonitz, A. Filinov

The ground state and the excitation spectrum of strongly correlated electrons in quantum dots are investigated. An analytical solution is constructed by exact diagonalization of the Hamiltonian in terms of the $N$-particle eigenmodes.

Arnaud Verger, Cristiano Ciuti, Iacopo Carusotto

We investigate the quantum nonlinear dynamics of a resonantly excited photonic quantum dot embedding a quantum well in the strong exciton-photon coupling regime. Within a master equation approach, we study the polariton quantum blockade and the generation of single photon states due to polariton-polariton interactions as a function of the photonic dot geomet

Devang A. Joshi, C. V. Tomy D. S. Rana, R. Nagarajan, S. K. Malik

The magnetic properties of RNi4Ga (R = La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm and Lu) compounds have been investigated. These compounds form in a hexagonal CaCu5 type structure with a space group P6/mmm. Compounds with the magnetic rare earths, R = Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm, undergo a ferromagnetic transition at 5 K, 17 K, 20 K, 19 K, 12 K, 3.5 K, 8

Iulian N. Hulea, Saverio Russo, Anna Molinari, Alberto F. Morpurgo

We have investigated the contact resistance of rubrene single-crystal field-effect transistors (FETs) with Nickel electrodes by performing scaling experiments on devices with channel length ranging from 200 nm up to 300 $μ$m. We find that the contact resistance can be as low as 100 $Ω$cm with narrowly spread fluctuations. For comparison, we have also perform

Yvan Castin, Zoran Hadzibabic, Sabine Stock, Jean Dalibard

We propose a physical system allowing one to experimentally observe the distribution of the complex zeros of a random polynomial. We consider a degenerate, rotating, quasi-ideal atomic Bose gas prepared in the lowest Landau level. Thermal fluctuations provide the randomness of the bosonic field and of the locations of the vortex cores. These vortices can be

B. Grabiec, S. Krawiec, M. Matlak

We find the eigenvalues $E_α $ and eigenvectors $|E_α>$ of the extended Hubbard dimer and we represent each part $E_α |E_α> < E_α |$ of the dimer Hamiltonian $(α=1,2,...,16)$in the second quantizations with the use of the Hubbard and spin operators. This procedure gives a review of all competitive, intrinsic interactions, deeply hidden in the orginal form of

Y. Shuto, M. Tanaka, S. Sugahara

A new group-IV ferromagnetic semiconductor, Ge1-xFex, was successfully grown by low-temperature molecular beam epitaxy (LT-MBE) without precipitation of ferromagnetic Ge-Fe intermetallic compounds. The ferromagnetism of Ge1-xFex films was investigated by magnetic circular dichroism (MCD). In particular, the influence of the Fe content (FFe/FGe =1 - 10%) and

M. Schmid, A. Renner, F. J. Giessibl

Cleaving crystals in a vacuum chamber is a simple method for obtaining atomically flat and clean surfaces for materials that have a preferential cleaving plane. Most in-situ cleavers use parallel cutting edges that are applied from two sides on the sample. We found in ambient experiments that diagonal cutting pliers, where the cleavage force is introduced in

Thomas P. Papageorgiou, Ennio Casini, Hans F. Braun, Thomas Herrmannsdörfer

Magnetic-field changes $<$ 0.2 Oe over the scan length in magnetometers that necessitate sample movement are enough to create artifacts in the dc magnetization measurements of the weakly ferromagnetic superconductor RuSr$_{2}$GdCu$_{2}$O$_{8}$ (Ru1212) below the superconducting transition temperature $T_{c} \approx$ 30 K. The observed features depend on the

Wouter Wetzels, Gerrit E. W. Bauer, Oleg N. Jouravlev

We propose to accelerate reversal of the ferromagnetic order parameter in spin valves by electronic noise. By solving the stochastic equations of motion we show that the current-induced magnetization switching time is drastically reduced by a modest level of externally generated current (voltage) noise. This also leads to a significantly lower power consumpt

K. Shimatake, Y. Toda, S. Tanda

The comparison of the single-particle (SP) dynamics between the whisker and ring NbSe$_3$ crystals provides new insight into the phase transition properties in quasi-one-dimensional charge density wave (CDW) systems.

Kiran M. Kolwankar

We generalise the Langevin equation with Gaussian white noise by replacing the velocity term by a local fractional derivative. The solution of this equation is a Levy process. We further consider the Brownian motion of a fractal particle, for example, a colloidal aggregate or a biological molecule and argue that it leads to a Levy flight. This effect can als

I. Makkonen, M. Hakala, M. J. Puska

Measuring the Doppler broadening of the positron annihilation radiation or the angular correlation between the two annihilation gamma quanta reflects the momentum distribution of electrons seen by positrons in the material.Vacancy-type defects in solids localize positrons and the measured spectra are sensitive to the detailed chemical and geometric environme

A. L. Chernyshev

We study the effects of external magnetic field on the properties of an ordered Heisenberg antiferromagnet with the Dzyaloshinskii-Moriya (DM) interaction. Using the spin-wave theory quantum correction to the energy, on-site magnetization, and uniform magnetization are calculated as a function of the field H and the DM anisotropy constant D. It is shown that

N. Ya. Fogel, E. I. Buchstab, Yu. V. Bomze, O. I. Yuzephovich

We have discovered superconductivity in the two-layer semiconducting monochalcogenide heterostrutures PbTe/PbS, PbTe/PbSe and PbTe/YbS. By comparing data from two-layer samples with data from single monochalcogenide films we conclude that the superconductivity is connected with the interface between the two semiconductors. Evidence for the low dimensional na

A. N. Straughn, S. H. Cohen, R. E. Ryan, N. P. Hathi

In the Hubble Ultra Deep Field (HUDF) an abundance of galaxies is seen with a knot at one end plus an extended tail, resembling a tadpole. These &#34;tadpole galaxies&#34; appear dynamically unrelaxed--presumably in an early merging state--where tidal interactions likely created the distorted knot-plus-tail morphology. Here we systematically select tadpole g

S. J. U. Higdon, J. L. Higdon, J. Marshall

We observed two faint tidal dwarf galaxies (TDGs), NGC 5291N and NGC 5291 S with the Infrared Spectrograph on the Spitzer Space Telescope. We detect strong polycyclic aromatic hydrocarbon (PAH) emission, which match models of groups of \~100 carbon atoms with an equal mixture of neutral and ionized PAHs. The TDGs have a dominant warm ~140 K dust component in

D. Apai, I. Pascucci, J. Bouwman, A. Natta

The onset of planet formation in protoplanetary disks is marked by the growth and crystallization of sub-micron-sized dust grains accompanied by dust settling toward the disk mid-plane. Here we present infrared spectra of disks around brown dwarfs and brown dwarf candidates. We show that all three processes occur in such cool disks in a way similar or identi

S. J. Peale

In determining Mercury&#39;s core structure from its rotational properties, the value of the normalized moment of inertia, $C/MR^2$, from the location of Cassini 1 is crucial. If Mercury&#39;s spin axis occupies Cassini state 1, its position defines the location of the state. The spin might be displaced from the Cassini state if the spin is unable to follow

David Yong, Wako Aoki, David L. Lambert, Diane B. Paulson

We present measurements of the neutron-capture elements Rb and Pb in five giant stars of the globular cluster NGC 6752 and Pb measurements in four giants of the globular cluster M 13. The abundances were derived by comparing synthetic spectra with high resolution, high signal-to-noise ratio spectra obtained using HDS on the Subaru telescope and MIKE on the M

M. Ali Alpar, Dimitrios Psaltis

In the inner regions of accretion disks around compact objects, the orbital frequency of the gas deviates from the local Keplerian value. For long-wavelength modes in this region, the radial epicyclic frequency kappa is higher than the azimuthal frequency Omega. This has significant implications for models of the twin kHz QPOs observed in many neutron-star s

D. Thomas, F. Brimioulle, R. Bender, U. Hopp

We present optical long-slit spectra of the Virgo dwarf elliptical galaxy VCC 510 at high spectral and spatial resolution. Heliocentric velocities and velocity dispersions as functions of galaxy radius are derived by deconvolving line-of-sight velocity distributions. A maximum rotation v_rot=8 km/s inside half the effective radius (re~20 arcsec) and a mean,

Marijke Haverkorn, Bryan M. Gaensler, Jo-Anne C. Brown, Naomi M. McClure-Griffiths

The Southern Galactic Plane Survey (SGPS) is a 1.4 GHz radio polarization and HI survey in a large part of the inner Galactic plane at a resolution of about an arcmin. Depolarization and Faraday rotation of polarized radiation from diffuse Galactic synchrotron emission, pulsars, and extragalactic sources can be used to infer information about the strength an

M. M. Miller Bertolami, L. G. Althaus, A. M. Serenelli, J. A. Panei

We present evolutionary calculations aimed at describing the born-again scenario for post-AGB remnant stars of 0.5842 and 0.5885 \msun. Results are based on a detailed treatment of the physical processes responsible for the chemical abundance changes. We considered two theories of convection: the standard mixing length theory (MLT) and the double-diffusive G

M. A. Stark, Richard A. Wade

We present the results of a study of the late-type companions in hot subdwarf composite spectrum binaries. The exact nature of these late-type companions has been disputed in the literature -- some argue that they are main sequence stars, and others have claimed they are subgiants. To determine the properties of the late-type companions, we first conducted a

Richard A. Wade, M. A. Stark, R. F. Green, P. R. Durrell

Many EHB stars have been found in short-period binaries, where the companions in these post-common envelope systems are either white dwarfs or dM stars; these systems are catalogued as hot subdwarfs because the subdwarf is the more luminous component. Hypothesized Roche-lobe overflow systems (with more massive companions) may largely be uncatalogued, since t