Selected results on Strong and Coulomb-induced correlations from the STAR experiment

Using recent high-statistics STAR data from Au+Au and Cu+Cu collisions at full RHIC energy I discuss strong and Coulomb-induced final state interaction effects on identical ($\pi-\pi$) and non-identical ($\pi-\Xi$) particle correlations. Analysis of $\pi-\Xi$ correlations reveals the strong and Coulomb-induced FSI effects allowing for the first time to estimate space extension of $\pi$ and $\Xi$ sources and average shift between them. Source imaging technique providing clean separation of these effects from effects due to the source function itself is applied to one-dimensional relative momentum correlation function of identical pions. For low momentum pions and/or non-central collisions large departure from a single-Gaussian shape is observed

Centrality Dependence of Azimuthal Anisotropy of Strange Hadrons in 200 GeV Au+Au Collisions

Measurements of azimuthal anisotropy for strange and multi-strange hadrons are presented for the first time in their centrality dependence. The high statistics results of v2(pT) allow for a more detailed comparison to hydrodynamical model calculations. Number-of-constituent-quark scaling was tested for different centrality classes separately. Higher order anisotropies like v4(pT) are measured for multi-strange hadrons. While we observe agreement between measured data and models a deeper understanding and refinement of the models seem to be necessary in order to fully understand the details of the data.Comment: 4 pages, 2 figures; Strange Quark Matter 2006 conference proceedings, to appear in J. Phys.

How well does NLO pQCD describe strangeness in p+pp+p collisions at s\sqrt{s}= 200 GeV in STAR?

We present measurements of the transverse momentum spectra for $\mathrm{K^{0}_{S}}$, $\Lambda$, $\Xi$ and their antiparticles in p+p collisions at $\sqrt{s}=200 GeV$. The extracted mid-rapidity yields and $$ are in agreement with previous $p+\bar{p}$ experiments while they have smaller statistical errors. We compare the measured spectra for $\mathrm{K^{0}_{S}}$ and $\Lambda$ to the latest available calculations from NLO pQCD and see good agreement for the $\mathrm{K^{0}_{S}}$ above 1.5 GeV/c.Comment: conference proceedings, Strangeness in Quark Matter 2004, 5 pages, submitted to Journal Physics G, final version submitted to journal incl. modifications requested by edito

Three-way electrical gating characteristics of metallic Y-junction carbon nanotubes

Y-junction based carbon nanotube (CNT) transistors exhibit interesting switching behaviors, and have the structural advantage that the electrical gate for current modulation can be formed by any of the three constituent branches. In this letter, we report on the gating characteristics of metallic Y-CNT morphologies. By measuring the output conductance and transconductance we conclude that the efficiency and gain depend on the branch diameter and is electric field controlled. Based on these principles, we propose a design for a Y-junction based CNT switching device, with tunable electrical properties

New approach to nonlinear electrodynamics: dualities as symmetries of interaction

We elaborate on the duality-symmetric nonlinear electrodynamics in a new formulation with auxiliary tensor fields. The Maxwell field strength appears only in bilinear terms of the corresponding generic Lagrangian, while the self-interaction is presented by a function E depending on the auxiliary fields. Two types of dualities inherent in the nonlinear electrodynamics models admit a simple off-shell characterization in terms of this function. In the standard formulation, the continuous U(1) duality symmetry is nonlinearly realized on the Maxwell field strength. In the new setting, the same symmetry acts as linear U(1) transformations of the auxiliary field variables. The nonlinear U(1) duality condition proves to be equivalent to the linear U(1) invariance of the self-interaction E. The discrete self-duality (or self-duality by Legendre transformation) amounts to a weaker reflection symmetry of E. For a class of duality- symmetric Lagrangians we introduce an alternative representation with the auxiliary scalar field and find new explicit examples of such systems.Comment: Latex file, 21 page

Application of the operator product expansion to the short distance behavior of nuclear potentials

We investigate the short distance behavior of nucleon-nucleon (NN) potentials defined through Bethe-Salpeter wave functions, by perturbatively calculating anomalous dimensions of 6-quark operators in QCD. Thanks to the asymptotic freedom of QCD, 1-loop computations give certain exact results for the potentials in the zero distance limit. In particular the functional form of the S-state central NN potential at short distance $r$ is predicted to be a little weaker than $r^{-2}$. On the other hand, due to the intriguing character of the anomalous dimension spectrum, perturbative considerations alone can not determine whether this potential is repulsive or attractive at short distances. A crude estimation suggests that the force at short distance is repulsive, as found numerically in lattice QCD. A similar behavior is found for the tensor potential.Comment: 40 pages, no figure

Première note sur quelques endoparasites des animaux sauvages de Haute-Casamance

L'étude d'un premier lot de parasites internes (Nematoda et Pentastoma) récoltés à l'autopsie de mammifères, oiseaux et reptiles de Haute-Casamance (Sénégal) a permis de signaler: Chez Varanus niloticus : Hastospiculum macrophollus (Parona 1889), Tauqua tiara (o.v. Linstow, 1879); chez Corocias naevius et C. abyssinicus : un Squamofilaria qui pourrait appartenir à l'espèce S. coronata (Rud. 1809); chez Meliarax metabates (faucon) : un Thelazia localisé à l'oeil. Chez Erythrocebus patas Schreber : Stryptopharagus pigmentatus (o. v. Linstow, 1897). Chez un singe vert (Cercopithecus aethiops var. sabaeus L. et sur Sylvicapra grimmia) : Protospirura muricola Gedoelst, 1918; chez Cercopithecus aethiops var. sabaeus et ichneumia aloicauda Cuv. (mangouste à queue blanche) : Les formes nymphales de Nettorhynchus (Armillifer) armillatus (Wyman, 1845) Pentastoma. Un second lot de nématodes comportant notamment un certain nombre de Physaloptera parasites de l'estomac des singes et des petits carnivores ainsi que des filaires d'oiseaux et de mammifères appartenant aux genres Diplotriaena Railliet et Henry, 1909, Setaria Wiborg, 1795, Dicrofilaria Railliet et Henry, 1911 est en cours d'étude et fera l'objet d'une note ultérieur

Assessing senescence patterns in populations of large mammals

Theoretical models such as those of Gompertz and Weibull are commonly used to study senescence in survival for humans and laboratory or captive animals. For wild populations of vertebrates, senescence in survival has more commonly been assessed by fitting simple linear or quadratic relationships between survival and age. By using appropriate constraints on survival parameters in Capture-Mark-Recapture (CMR) models, we propose a first analysis of the suitability of the Gompertz and the two-parameter Weibull models for describing aging-related mortality in free-ranging populations of ungulates. We first show how to handle the Gompertz and the two-parameter Weibull models in the context of CMR analyses. Then we perform a comparative analysis of senescence patterns in both sexes of two ungulate species highly contrasted according to the intensity of sexual selection. Our analyses provide support to the Gompertz model for describing senescence patterns in ungulates. Evolutionary implications of our results are discusse

Dynamics of the Born-Infeld dyons

The approach to the dynamics of a charged particle in the Born-Infeld nonlinear electrodynamics developed in [Phys. Lett. A 240 (1998) 8] is generalized to include a Born-Infeld dyon. Both Hamiltonian and Lagrangian structures of many dyons interacting with nonlinear electromagnetism are constructed. All results are manifestly duality invariant.Comment: 11 pages, LATE

Semileptonic Hyperon Decays and CKM Unitarity

Using a technique that is not subject to first-order SU(3) symmetry breaking effects, we determine the $V_{us}$ element of the CKM matrix from data on semileptonic hyperon decays. We obtain $V_{us}$ =0.2250(27). This value is of similar precision to the one derived from $K_{l3}$, but higher and in better agreement with the unitarity requirement, $|V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=1$.Comment: 3 pages, 1 tabl