66 research outputs found

    New Analyses of Double-Bang Events in the Atmosphere

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    We use CORSIKA+Herwig simulation code to produce ultra-high energy neutrino interactions in the atmosphere. Our aim is to reproduce extensive air showers originated by extragalactic tau-neutrinos. For charged current tau-neutrino interactions in the atmosphere, beside the air shower originated from the neutrino interaction, it is expected that a tau is created and may decay before reaching the ground. That phenomenon makes possible the generation of two related extensive air showers, the so called Double-Bang event. We make an analysis of the main characteristics of Double-Bang events in the atmosphere for mean values of the parameters involved in such phenomenon, like the inelasticity and tau decay length. We discuss what may happen for the ``out of the average'' cases and conclude that it may be possible to observe this kind of event in ultra-high energy cosmic ray observatories such as Pierre Auger or Telescope Array.Comment: 17 pages, 5 figures, final version to appear in BJ

    Quantum Dissipation in a Neutrino System Propagating in Vacuum and in Matter

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    Considering the neutrino state like an open quantum system, we analyze its propagation in vacuum or in matter. After defining what can be called decoherence and relaxation effects, we show that in general the probabilities in vacuum and in constant matter can be written in a similar way, which is not an obvious result in this approach. From this result, we analyze the situation where neutrinos evolution satisfies the adiabatic limit and use this formalim to study solar neutrinos. We show that the decoherence effect may not be bounded by the solar neutrino data and review some results in the literature. We discuss the current results where solar neutrinos were used to put bounds on decoherence effects through a model-dependent approach. We conclude explaining how and why this models are not general and we reinterpret these constraints.Comment: new version: title was changend and was added a table. To appear at Nucl. Physic.

    Equivalence between quantum mechanics and pt symmetric quantum mechanics

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    Sem informa√ß√£oIn this paper we develop a discussion about PT symmetric quantum mechanics, working with the basic elements of this theory. In a simple case of a two-body system, we developed the quantum brachistochrone problem. Comparing the results obtained through the PT symmetric quantum mechanics with the ones obtained using the standard formalism, we conclude that this new approach is not able to reveal any new effect. ¬© The Sociedade Brasileira de F√≠sica.Este artigo traz uma discuss√£o a respeito da mec√Ęnica qu√Ęntica PT sim√©trica, desenvolvendo alguns elementos b√°sicos dessa teoria. Em um caso simples de sistema de dois n√≠veis, desenvolvemos o problema da braquist√≥crona qu√Ęntica. Comparando os resultados obtidos entre a mec√Ęnica qu√Ęntica PT sim√©trica e aqueles obtidos usando o formalismo padr√£o, conclui-se que a nova abordagem n√£o √© capaz de revelar nenhum fen√īmeno novo.37119Sem informa√ß√£oSem informa√ß√£oSem informa√ß√£oBender, C.M., Boettcher, S., (1998) Phys. Rev. Lett., 80, p. 5243Bender, C.M., Brody, D.C., Jones, H.F., (2004) Phys. Rev. Lett., 93Znojil, M., (2001), arXiv:math-phBender, C.M., Brody, D.C., Jones, H.F., (2002) Phys. Rev. Lett., 89Bender, C.M., Boettcher, S., (2013) Physica Scripta, 87Jun-Qing Li, Y.-G.M., (2012) Phys. Rev. A, 85Borisov, D.I., (2013) Proceedings of the Steklov Institute of Mathematics, 281, p. 5Mostafazadeh, A., (2002) J. Math. Phys., 43, p. 205Carlini, A., Hosoya, A., Koike, T., Okudaira, Y., (2006) Phys. Rev. Lett., 96Brody, D.C., Hook, D.W., (2006) J. Phys. A: Mathematical and General, 39, p. 167Bender, C.M., Brody, D.C., Jones, H.F., Meister, B.K., (2007) Phys. Rev. Lett., 98Mezincescu, G.A., (2000) J. Phys. A: Mathematical and General, 33, p. 4911Bender, C.M., Wang, Q., (2001) J. Phys. A: Mathematical and General, 34, p. 3325Bender, C., (2003) Rep. Prog. Phys, 70, p. 947Weigert, S., (2003) Phys. Rev. A, 68Bender, C.M., Klevansky, S., (2009) Phys. Lett. A, 373, p. 2670Mostafazadeh, A., (2007) Phys. Rev. Lett., 99In this paper we develop a discussion about PT symmetric quantum mechanics, working with the basic elements of this theory. In a simple case of a two-body system, we developed the quantum brachistochrone problem. Comparing the results obtained through the PT symmetric quantum mechanics with the ones obtained using the standard formalism, we conclude that this new approach is not able to reveal any new effect

    Analysis of a modern hybrid and an ancient sugarcane implicates a complex interplay of factors in affecting recalcitrance to cellulosic ethanol production

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    Abundant evidence exists to support a role for lignin as an important element in biomass recalcitrance. However, several independent studies have also shown that factors apart from lignin are also relevant and overall, the relative importance of different recalcitrance traits remains in dispute. In this study we used two genetically distant sugarcane genotypes, and performed a correlational study with the variation in anatomical parameters, cell wall composition, and recalcitrance factors between these genotypes. In addition we also tracked alterations in these characteristics in internodes at different stages of development. Significant differences in the development of the culm between the genotypes were associated with clear differential distributions of lignin content and composition that were not correlated with saccharification and fermentation yield. Given the strong influence of the environment on lignin content and composition, we hypothesized that sampling within a single plant could allow us to more easily interpret recalcitrance and changes in lignin biosynthesis than analysing variations between different genotypes with extensive changes in plant morphology and culm anatomy. The syringyl/guaiacyl (S/G) ratio was higher in the oldest internode of the modern genotype, but S/G ratio was not correlated with enzymatic hydrolysis yield nor fermentation efficiency. Curiously we observed a strong positive correlation between ferulate ester level and cellulose conversion efficiency. Together, these data support the hypothesis that biomass enzymatic hydrolysis recalcitrance is governed by a quantitative heritage rather than a single trait

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure
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