1,596 research outputs found

    Breaking Eight-fold Degeneracies in Neutrino CP Violation, Mixing, and Mass Hierarchy

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    We identify three independent two-fold parameter degeneracies (\delta, \theta_{13}), sgn(\delta m^2_{31}) and (\theta_{23}, \pi/2-\theta_{23}) inherent in the usual three-neutrino analysis of long-baseline neutrino experiments, which can lead to as much as an eight-fold degeneracy in the determination of the oscillation parameters. We discuss the implications these degeneracies have for detecting CP violation and present criteria for breaking them. A superbeam facility with a baseline at least as long as the distance between Fermilab and Homestake (1290 km) and a narrow band beam with energy tuned so that the measurements are performed at the first oscillation peak can resolve all the ambiguities other than the (\theta_{23}, \pi/2-\theta_{23}) ambiguity (which can be resolved at a neutrino factory) and a residual (\delta, \pi-\delta) ambiguity. However, whether or not CP violation occurs in the neutrino sector can be ascertained independently of the latter two ambiguities. The (\delta,\pi-\delta) ambiguity can be eliminated by performing a second measurement to which only the \cos\delta terms contribute. The hierarchy of mass eigenstates can be determined at other oscillation peaks only in the most optimistic conditions, making it necessary to use the first oscillation maximum. We show that the degeneracies may severely compromise the ability of the proposed SuperJHF-HyperKamiokande experiment to establish CP violation. In our calculations we use approximate analytic expressions for oscillation probabilitites that agree with numerical solutions with a realistic Earth density profile.Comment: Revtex (singlespaced), 35 pages, 15 postscript figures, uses psfig.st

    Neutrino Factories and the "Magic" Baseline

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    We show that for a neutrino factory baseline of L7300km7600kmL \sim 7300 km - 7 600 km a ``clean'' measurement of sin22θ13\sin^2 2 \theta_{13} becomes possible, which is almost unaffected by parameter degeneracies. We call this baseline "magic" baseline, because its length only depends on the matter density profile. For a complete analysis, we demonstrate that the combination of the magic baseline with a baseline of 3000 km is the ideal solution to perform equally well for the sin22θ13\sin^2 2 \theta_{13}, sign of Δm312\Delta m_{31}^2, and CP violation sensitivities. Especially, this combination can very successfully resolve parameter degeneracies even below sin22θ13<104\sin^2 2 \theta_{13} < 10^{-4}.Comment: Minor changes, final version to appear in PRD, 4 pages, 3 figures, RevTe

    Design and validation of a socio-emotional questionnaire for youth football players

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    Con el objetivo de detectar y controlar los factores socio-emocionales que influyen en la progresión del joven futbolista, se diseñó un cuestionario auto-cumplimentado de 40 ítems, agrupados en 3 dimensiones (entorno social, bienestar e inteligencia emocional). Se analizó la validez de contenido mediante la valoración de 14 expertos y la validez de constructo mediante análisis factorial. Se evaluó la fiabilidad del cuestionario, administrándolo a jóvenes futbolistas de élite (n=281) y analizando la consistencia interna por el método del Alfa de Cronbach y la fiabilidad test-retest mediante el coeficiente de correlación intraclase (CCI). El análisis factorial confirmó la existencia de 18 categorías, que en conjunto explican el 65,40% de la varianza total. El Alfa de Cronbach del cuestionario fue de 0,944 (p<0,01) y el CCI de 0,894 (p<0,01). El cuestionario reúne suficientes propiedades psicométricas como para ser considerado una herramienta válida y fiable para medir el entorno socio-emocional de jóvenes futbolistas.The objective of this study was to design a valid questionnaire to detect and manage the socio-emotional factors that influence the performance of young football players. A group of specialists designed a self-completion questionnaire of 40 items grouped into 3 dimensions. Content validity was analysed and evaluated by 14 experts and construct validity was analysed by factorial analysis. To evaluate reliability the questionnaire was administered to young elite football players, and internal consistency was analysed with Cronbach’s alpha. Test-retest reliability was assessed with the intraclass correlation coefficient (ICC). Factor analysis confirmed the existence of 18 factors, which as a whole explained 65.40% of the total variance. The Cronbach’s alpha of the questionnaire was 0.944 (p<0.01) and the ICC of the entire questionnaire was 0.894 (p<0.01). The questionnaire gathers together enough psychometric properties to be considered a valid and reliable tool for gauging the socio-emotional environment of young football players

    Coupling theory for counterion distributions based in Tsallis statistics

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    It is well known that the Poisson-Boltzmann (PB) equation yields the exact counterion density around charged objects in the weak coupling limit. In this paper we generalize the PB approach to account for coupling of arbitrary strength by making use of Tsallis q-exponential distributions. Both the weak coupling and the strong coupling limits are reproduced. For arbitrary coupling we also provide simple analytical expressions which are compared to recent Monte Carlo simulations by A. G. Moreira and R. R. Netz [Europhys. Lett. 52 (2000) 705]. Excellent agreement with these is obtained.Comment: 17 pages, 2 figures, 1 table. Final version, accepted for publication in Physica

    How two neutrino superbeam experiments do better than one

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    We examine the use of two superbeam neutrino oscillation experiments with baselines \lsim 1000 km to resolve parameter degeneracies inherent in the three-neutrino analysis of such experiments. We find that with appropriate choices of neutrino energies and baselines two experiments with different baselines can provide a much better determination of the neutrino mass ordering than a single experiment alone. Two baselines are especially beneficial when the mass scale for solar neutrino oscillations δmsol2\delta m^2_{\rm sol} is \gsim 5\times10^{-5} eV2^2. We also examine CP violation sensitivity and the resolution of other parameter degeneracies. We find that the combined data of superbeam experiments with baselines of 295 and 900 km can provide sensitivity to both the neutrino mass ordering and CP violation for sin22θ13\sin^22\theta_{13} down to 0.03 for δmatm23×103|\delta m^2_{\rm atm}| \simeq 3\times10^{-3} eV2^2. It would be highly advantageous to have a 10% determination of δmatm2|\delta m^2_{\rm atm}| before the beam energies and baselines are finalized, although if δmatm2|\delta m^2_{\rm atm}| is not that well known, the neutrino energies and baselines can be chosen to give fairly good sensitivity for a range of δmatm2|\delta m^2_{\rm atm}|.Comment: 18 pages, 6 PS figures, added references and revised discussio

    Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

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    Magnetic refrigeration based on the magnetocaloric effect at room temperature is one of the most attractive alternative to the current gas compression/expansion method routinely employed. Nevertheless, in giant magnetocaloric materials, optimal refrigeration is restricted to the narrow temperature window of the phase transition (Tc). In this work, we present the possibility of varying this transition temperature into a same giant magnetocaloric material by ion irradiation. We demonstrate that the transition temperature of iron rhodium thin films can be tuned by the bombardment of ions of Ne 5+ with varying fluences up to 10 14 ions cm --2 , leading to optimal refrigeration over a large 270--380 K temperature window. The Tc modification is found to be due to the ion-induced disorder and to the density of new point-like defects. The variation of the phase transition temperature with the number of incident ions opens new perspectives in the conception of devices using giant magnetocaloric materials

    Matter profile effect in neutrino factory

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    We point out that the matter profile effect --- the effect of matter density fluctuation on the baseline --- is very important to estimate the parameters in a neutrino factory with a very long baseline. To make it clear, we propose the method of the Fourier series expansion of the matter profile. By using this method, we can take account of both the matter profile effect and its ambiguity. For very long baseline experiment, such as L=7332km, in the analysis of the oscillation phenomena we need to introduce a new parameter a1 a_{1} --- the Fourier coefficient of the matter profile --- as a theoretical parameter to deal with the matter profile effects.Comment: 21 pages, 15 figure

    Neutrino oscillation parameters from MINOS, ICARUS and OPERA combined

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    We perform a detailed analysis of the capabilities of the MINOS, ICARUS and OPERA experiments to measure neutrino oscillation parameters at the atmospheric scale with their data taken separately and in combination. MINOS will determine Δm322\Delta m^2_{32} and sin22θ23\sin^2 2\theta_{23} to within 10% at the 99% C.L. with 10 kton-years of data. While no one experiment will determine sin22θ13\sin^2 2\theta_{13} with much precision, if its value lies in the combined sensitivity region of the three experiments, it will be possible to place a lower bound of O(0.01) at the 95% C.L. on this parameter by combining the data from the three experiments. The same bound can be placed with a combination of MINOS and ICARUS data alone.Comment: Version to appear in PR
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