25,768 research outputs found

    Getting the most from NOvA and T2K

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    The determination of the ordering of the neutrino masses (the hierarchy) is probably a crucial prerequisite to understand the origin of lepton masses and mixings and to establish their relationship to the analogous properties in the quark sector. In this talk, we follow an alternative strategy to the usual neutrino--antineutrino comparison: we exploit the combination of the neutrino-only data from the NOvA and the T2K experiments by performing these two off-axis experiments at different distances but at the same /L/L, being the mean neutrino energy and LL the baseline. This would require a minor adjustment to the proposed off-axis angle for one or both of the proposed experiments.Comment: 7 pages, 2 figures, Proccedings of Neutrino 2006 Conference, Santa Fe, New Mexico, June 13-19, 200

    Puzzling out Neutrino Mixing Through Golden and Silver Measurements

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    We update a recent work devoted to resolve the degeneracies that appear in the simultaneous extraction of θ13\theta_{13} and δ\delta at future Neutrino Factories (NF, that exploit the \emph{golden} channels, i.e. νeνμ\nu_e\to\nu_\mu (νˉeνˉμ\bar{\nu}_e\to\bar{\nu}_\mu)) and Superbeam experiments (SB, that measure the νμνe\nu_\mu\to\nu_e (νˉμνˉe\bar{\nu}_\mu\to\bar{\nu}_e) transitions). We consider the neutrino fluxes obtained with a new optics design for the CERN-SPL SB and assume the solar parameters within the LMA-I and the LMA-II regions indicated by recent KamLAND data. The dangerous fake solution associated with the θ23\theta_{23}-ambiguity remains after the combination of data from these two facilities: in this perspective, we analyze the impact of the NF-\emph{silver} channels, i.e. νeντ\nu_e\to\nu_\tau (νˉeνˉτ\bar{\nu}_e\to\bar{\nu}_\tau). The combination of data from these three experiments -NF(\emph{golden} and \emph{silver} channels) plus SPL SB- can discover leptonic CP violation for values of θ131\theta_{13}\ge 1^{\circ}.Comment: 6 pages, 8 figures. Presented at XXXVIII Rencontre De Moriond: Electroweak Interactions and Unified Theories Les Arcs, France, March 15--22, 200

    Christian Democracy: The Right Solution to Underdevelopment?

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    Trivalent Graph isomorphism in polynomial time

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    It's important to design polynomial time algorithms to test if two graphs are isomorphic at least for some special classes of graphs. An approach to this was presented by Eugene M. Luks(1981) in the work \textit{Isomorphism of Graphs of Bounded Valence Can Be Tested in Polynomial Time}. Unfortunately, it was a theoretical algorithm and was very difficult to put into practice. On the other hand, there is no known implementation of the algorithm, although Galil, Hoffman and Luks(1983) shows an improvement of this algorithm running in O(n3logn)O(n^3 \log n). The two main goals of this master thesis are to explain more carefully the algorithm of Luks(1981), including a detailed study of the complexity and, then to provide an efficient implementation in SAGE system. It is divided into four chapters plus an appendix.Comment: 48 pages. It is a Master Thesi

    A Study of the Assimilative Behavior of the Voiced Labio-Dental Fricative in American English

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    Gradation is one of the main features of colloquial speech. It implies the presence of certain phonological processes that ease the transition between phonemes with different articulatory features. For English, one of these implied processes is assimilation, which is when the articulation of a segment is modified into another one already existing in the system. Our study takes Gimson (1994)’s suggestion that /v/ assimilates into /m/ when it is followed by the bilabial nasal. After observing and describing different cases of assimilation, we suggest more possible explanations to this phenomenon and more assimilative behaviors of /v/. Therefore, we conduct an experiment with six American- English L1s where they evaluate sentences whose articulation includes our suggested proposals. The results show Gimson’s theory not to be as accurate as expected. Furthermore, we prove that /v/ can assimilate into /b/, /ɂ/ and /d/ when it is followed by bilabial, velar and alveolar phonemes.La gradación es una de las características más significativas del lenguaje coloquial. Esta implica la presencia de ciertos procesos fonológicos que facilitan la transición entre fonemas con distintas articulaciones. En el caso del inglés, uno de estos procesos es la asimilación, que consiste en cambiar la articulación de un segmento por la de otro existente en el sistema. Este estudio se basa en la propuesta de Gimson (1994), por la que /v/ se asimila a /m/ cuando le sigue la bilabial nasal. Tras observar y describir más casos de asimilación, nos planteamos distintos comportamientos asimilativos de /v/ en este y otros contextos, que fueron evaluados por medio de un experimento realizado a seis nativos de inglés-americano. Los resultados muestran que la teoría de Gimson no es tan apropiada como se esperaba. Además, concluimos que /v/ puede asimilar a /b/, /ɂ/ y /d/ cuando le siguen ciertos sonidos bilabiales, velares y alveolares.Grado en Estudios Inglese

    Large quantum gravity effects: Cylindrical waves in four dimensions

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    Linearly polarized cylindrical waves in four-dimensional vacuum gravity are mathematically equivalent to rotationally symmetric gravity coupled to a Maxwell (or Klein-Gordon) field in three dimensions. The quantization of this latter system was performed by Ashtekar and Pierri in a recent work. Employing that quantization, we obtain here a complete quantum theory which describes the four-dimensional geometry of the Einstein-Rosen waves. In particular, we construct regularized operators to represent the metric. It is shown that the results achieved by Ashtekar about the existence of important quantum gravity effects in the Einstein-Maxwell system at large distances from the symmetry axis continue to be valid from a four-dimensional point of view. The only significant difference is that, in order to admit an approximate classical description in the asymptotic region, states that are coherent in the Maxwell field need not contain a large number of photons anymore. We also analyze the metric fluctuations on the symmetry axis and argue that they are generally relevant for all of the coherent states.Comment: Version accepted for publication in Int. J. Mod. Phys.