Precise nondivergent analytic formulas for the radiative corrections to the beta energy spectrum in hyperon semileptonic decays over the entire Dalitz plot

Very accurate analytical expressions for the radiative corrections of unpolarized hyperons semileptonic decays of charged and neutral baryons have been obtained in the recent past. Some of these formulas contain logarithmic singularities at the edges of the Dalitz plot for the three- and four-body decays. These singularities are analyzed and integrated analytically to obtain new divergentless formulas for the energy spectrum of the produced beta particle. The new equations contain terms of the order alpha times the momentum transfer, are applicable to any beta decay process and are suitable for a model-independent experimental analysis.Comment: 22 pages, 4 figure

Absolute single photoionization cross-sections of Br3+: Experiment and theory

Absolute single photoionization cross section measurements for Br3+ ions are reported in the photon energy range 44.79-59.54 eV at a photon energy resolution of 21 ±3 meV. Measurements were performed at the Advanced Light Source at Lawrence Berkeley National Laboratory using the merged-beams technique. Numerous resonance features in the experimental spectrum are assigned and their energies and quantum defect values are tabulated. The cross-section measurements are also compared with Breit-Pauli R-matrix calculations with suitable agreement over the photon energy range investigated. Analysis of the measured spectrum including Rydberg resonance series identifications produced a new emperical determination of the ionizational potential of Br3+ of 46.977 ± 0.050 eV, which is 805 meV lower than the most recently published value of 47.782 eV. This disparity between our determination and the earlier published value is similar to an 843 meV shift in the accepted ionization potential published for iso-electronic Se2+ as part of this same research program

MOCVD Growth of ZnO Nanowires Through Colloidal and Sputtered Au Seed Via Zn[TMHD]2 Precursor

AbstractZinc oxide (ZnO) nanowire (NW) arrays were grown on Si (100) substrate by metal-organic chemical vapor deposition (MOCVD) via Zn[TMHD]2 as precursor. Here we adopted two different procedures to grow ZnO NWs namely, colloid and sputtered Au pre-deposition on Si (100) substrate. Comparative studies based on the morphology and growth behavior of ZnO NWs were performed. The grown ZnO NWs were characterized by field-emission scanning electron microscopy (FE-SEM), Atomic Force Microscopy (AFM), Co-focal laser scanning microscopy (CLSM), and Raman spectroscopy

Radiative corrections to the Dalitz plot of K_{l3}^\pm decays

We calculate the model-independent radiative corrections to the Dalitz plot of K_{l3}^\pm decays to order (\alpha/\pi)(q/M_1), where q is the momentum transfer and M_1 is the mass of the kaon. The final results are presented, first, with the triple integration over the variables of the bremsstrahlung photon ready to be performed numerically and, second, in an analytical form. These two forms are useful to crosscheck on one another and with other calculations. This paper is organized to make it accessible and reliable in the analysis of the Dalitz plot of precision experiments and is not compromised to fixing the form factors at predetermined values. It is assumed that the real photons are kinematically discriminated. Otherwise, our results have a general model-independent applicability.Comment: RevTex4, 38 pages, 5 figures, 5 tables; some typos corrected; discussion extended to compare with other result

Semi-vortices and cluster-vorticity: new concepts in the Berezinskii-Kosterlitz-Thouless phase transition

The Berezinskii-Kosterlitz-Thouless (BKT) essential phase transition in the 2d XY model is revisited. Its mechanism is usually described by the (un)binding of vortex--anti-vortex (V--AV) pairs, which does, however, not provide a clear-cut quantitative criterion for criticality. Known sharp criteria are the divergence of the correlation length and a discontinuity of the helicity modulus. Here we propose and probe a new criterion: it is based on the concepts of semi-vortices and cluster vorticity, which are formulated in the framework of the multi-cluster algorithm that we use to simulate the 2d XY model.Comment: 6 pages, LaTex, 7 figures, presented at the "XXXV Reuni\'{o}n Anual de la Divisi\'{o}n de Part\'{i}culas y Campos", of the "Socieded Mexicana de F\'{i}sica", 2 references adde

Secuencia temporal en el swing de golf de jóvenes promesas

The golf swing is a skill which could be classified as a high velocity hitting where the main goal is that the head of the golf club reaches its maximum velocity at impact time. Ten golf swings executed by four young players were biomechanicaly analyze. Automatic capture with Vicon Oxford Metrics © was used. The absolute values of the linear velocities were higher at men that at women. At the interval analysis, the downswing presented less variation than the backswing. The analisis of the maximum timing sequence showed that depending on the gender they described different order. At men, the secuence started with the hip movement, followed by, left elbow, left shoulder and the club head. At women the hips and left elbow occurred simultaneously followed by the left shoulder and the club head. El swing en golf es una destreza que podríamos catalogar de golpeo de velocidad donde el objetivo es que la cara del palo alcance la máxima velocidad en el momento del impacto. Se han analizado biomecánicamente diez golpeos de cuatro jugadores promesas, mediante el sistema fotogrametría 3D Vicon Oxford Metrics © de captura automática. En primer lugar se ha podido comprobar que los valores absolutos de velocidades lineales eran mayores en los chicos que en los chicas. El análisis de las dos fases del swing indica que la fase de aceleración (downswing) presenta una variabilidad menor que el backwing. El análisis de la secuencia temporal de máximos alcanzados en los segmentos muestra cómo las aEcciones de los mismos siguen un orden diferente en función del género. La secuencia en los chicos empieza por el movimiento de caderas y sigue con el codo izquierdo, el hombro izquierdo y el palo; en las chicas, las caderas y el codo izquierdo actúan simultáneamente seguidos del hombro izquierdo y del palo.Peer Reviewe

An unusual new theropod with a didactyl manus from the upper cretaceous of patagonia, Argentina

Background Late Cretaceous terrestrial strata of the Neuquén Basin, northern Patagonia, Argentina have yielded a rich fauna of dinosaurs and other vertebrates. The diversity of saurischian dinosaurs is particularly high, especially in the late Cenomanian-early Turonian Huincul Formation, which has yielded specimens of rebacchisaurid and titanosaurian sauropods, and abelisaurid and carcharodontosaurid theropods. Continued sampling is adding to the known vertebrate diversity of this unit. Methodology/ Principal Findings A new, partially articulated mid-sized theropod was found in rocks from the Huincul Formation. It exhibits a unique combination of traits that distinguish it from other known theropods justifying erection of a new taxon, Gualicho shinyae gen. et sp. nov. Gualicho possesses a didactyl manus with the third digit reduced to a metacarpal splint reminiscent of tyrannosaurids, but both phylogenetic and multivariate analyses indicate that didactyly is convergent in these groups. Derived characters of the scapula, femur, and fibula supports the new theropod as the sister taxon of the nearly coeval African theropod Deltadromeus and as a neovenatorid carcharodontosaurian. A number of these features are independently present in ceratosaurs, and Gualicho exhibits an unusual mosaic of ceratosaurian and tetanuran synapomorphies distributed throughout the skeleton. Conclusions/ Significance Gualicho shinyae gen. et sp. nov. increases the known theropod diversity of the Huincul Formation and also represents the first likely neovenatorid from this unit. It is the most basal tetatanuran to exhibit common patterns of digit III reduction that evolved independently in a number of other tetanuran lineages. A close relationship with Deltadromaeus from the Kem Kem beds of Niger adds to the already considerable biogeographic similarity between the Huincul Formation and coeval rock units in North Africa.Fil: Apesteguía, Sebastián. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Smith, Nathan D.. Natural History Museum Of Los Angeles County; Estados UnidosFil: Valieri, Rubén Juárez. Provincia de Rio Negro; ArgentinaFil: Makovicky, Peter J.. Field Museum Of Natural History; Estados Unido

Equilibration of Concentrated Hard Sphere Fluids

We report a systematic molecular dynamics study of the isochoric equilibration of hard-sphere fluids in their metastable regime close to the glass transition. The thermalization process starts with the system prepared in a non-equilibrium state with the desired final volume fraction {\phi} but with a prescribed non-equilibrium static structure factor S_0(k; {\phi}). The evolution of the {\alpha}- relaxation time {\tau}{\alpha} (k) and long-time self-diffusion coefficient DL as a function of the evolution time tw is then monitored for an array of volume fractions. For a given waiting time the plot of {\tau}{\alpha} (k; {\phi}, tw) as a function of {\phi} exhibits two regimes corresponding to samples that have fully equilibrated within this waiting time ({\phi} \leq {\phi}(c) (tw)), and to samples for which equilibration is not yet complete ({\phi} \geq {\phi}(c) (tw)). The crossover volume fraction {\phi}(c) (tw) increases with tw but seems to saturate to a value {\phi}(a) \equiv {\phi}(c) (tw \rightarrow \infty) \approx 0.582. We also find that the waiting time t^(eq)_w({\phi}) required to equilibrate a system grows faster than the corresponding equilibrium relaxation time, t^(eq)({\phi}) \approx 0.27 \times [{\tau}{\alpha} (k; {\phi})]^1.43, and that both characteristic times increase strongly as {\phi} approaches {\phi}^(a), thus suggesting that the measurement of equilibrium properties at and above {\phi}(a) is experimentally impossible