512 research outputs found

    The sign of the day-night asymmetry for solar neutrinos

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    A qualitative understanding of the day-night asymmetry for solar neutrinos is provided. The greater night flux in nu_e is seen to be a consequence of the fact that the matter effect in the sun and that in the earth have the same sign. It is shown in the adiabatic approximation for the sun that for all values of the mixing angle theta_V between 0 and pi/2, the night flux of neutrinos is greater than the day flux. Only for small values of theta_V where the adiabatic approximation badly fails does the sign of the day-night asymmetry reverse.Comment: 3 pages, 3 figures, typos corrected and references adde

    Bound state solutions of the Dirac-Rosen-Morse potential with spin and pseudospin symmetry

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    The energy spectra and the corresponding two- component spinor wavefunctions of the Dirac equation for the Rosen-Morse potential with spin and pseudospin symmetry are obtained. The ss-wave (κ=0\kappa = 0 state) solutions for this problem are obtained by using the basic concept of the supersymmetric quantum mechanics approach and function analysis (standard approach) in the calculations. Under the spin symmetry and pseudospin symmetry, the energy equation and the corresponding two-component spinor wavefunctions for this potential and other special types of this potential are obtained. Extension of this result to κ0\kappa \neq 0 state is suggested.Comment: 18 page

    wd=1w_d=-1 in interacting quintessence model

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    A model consisting of quintessence scalar field interacting with cold dark matter is considered. Conditions required to reach wd=1w_d=-1 are discussed. It is shown that depending on the potential considered for the quintessence, reaching the phantom divide line puts some constraints on the interaction between dark energy and dark matter. This also may determine the ratio of dark matter to dark energy density at wd=1w_d=-1.Comment: 10 pages, references updated, some notes added, minor changes applied, accepted for publication in Eur. Phys. J.

    Neutrino-Deuteron Scattering in Effective Field Theory at Next-to-Next-to Leading Order

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    We study the four channels associated with neutrino-deuteron breakup reactions at next-to-next to leading order in effective field theory. We find that the total cross-section is indeed converging for neutrino energies up to 20 MeV, and thus our calculations can provide constraints on theoretical uncertainties for the Sudbury Neutrino Observatory. We stress the importance of a direct experimental measurement to high precision in at least one channel, in order to fix an axial two-body counterterm.Comment: 32 pages, 14 figures (eps

    Radiative Corrections to Neutrino Mixing and CP Violation in the Minimal Seesaw Model with Leptogenesis

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    Radiative corrections to neutrino mixing and CP violation are analyzed in the minimal seesaw model with two heavy right-handed neutrinos. We find that textures of the effective Majorana neutrino mass matrix are essentially stable against renormalization effects. Taking account of the Frampton-Glashow-Yanagida ansatz for the Dirac neutrino Yukawa coupling matrix, we calculate the running effects of light neutrino masses, lepton flavor mixing angles and CP-violating phases for both m1=0m_1 =0 (normal mass hierarchy) and m3=0m_3 =0 (inverted mass hierarchy) cases in the standard model and in its minimal supersymmetric extension. Very instructive predictions for the cosmological baryon number asymmetry via thermal leptogenesis are also given with the help of low-energy neutrino mixing quantities.Comment: 21 pages, 6 figures; more references adde

    Distribution of Energy-Momentum in a Schwarzschild-Quintessence Space-time Geometry

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    An analysis of the energy-momentum localization for a four-dimensional\break Schwarzschild black hole surrounded by quintessence is presented in order to provide expressions for the distributions of energy and momentum. The calculations are performed by using the Landau-Lifshitz and Weinberg energy-momentum complexes. It is shown that all the momenta vanish, while the expression for the energy depends on the mass MM of the black hole, the state parameter wqw_{q} and the normalization factor cc. The special case of wq=2/3w_{q}=-2/3 is also studied, and two limiting cases are examined.Comment: 9 page

    Discursive constructions of language and identity: parents' competing perspectives in London Turkish complementary schools

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    In this paper, I draw on interview data to explore parents' constructions of language and identity in two London Turkish complementary schools. I examine parents' evaluative talk about standard Turkish, Cypriot-Turkish and other regional varieties of Turkish, the cultural values they attach to them and images of personhood these invoke. I demonstrate how parents brought up in Turkey and Cyprus tend to privilege standard Turkish and acknowledge the crucial role Turkish complementary schools play as one of the key vehicles for its spread and promotion. Some parents, however, especially those politically active in promoting Cypriot-Turkish language, culture and history to the British-born generation, voice an alternative discourse where Cypriot-Turkish is intimately linked to their sense of self. Moreover, I investigate parents' perspectives of their children and of their own Turkish language competence in the case of parents brought up in the UK. I illustrate how their Turkish and their children's are compared against a ‘native’ speaker norm firmly located in the countries of origin. The parents' accounts show how different self- and other-ascriptions of proficiency in Turkish are linked to claims of or lack of ‘Turkishness’, largely shaped by their migration histories and narratives, personal and professional transnational experiences

    Dynamic Evolution of a Quasi-Spherical General Polytropic Magnetofluid with Self-Gravity

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    In various astrophysical contexts, we analyze self-similar behaviours of magnetohydrodynamic (MHD) evolution of a quasi-spherical polytropic magnetized gas under self-gravity with the specific entropy conserved along streamlines. In particular, this MHD model analysis frees the scaling parameter nn in the conventional polytropic self-similar transformation from the constraint of n+γ=2n+\gamma=2 with γ\gamma being the polytropic index and therefore substantially generalizes earlier analysis results on polytropic gas dynamics that has a constant specific entropy everywhere in space at all time. On the basis of the self-similar nonlinear MHD ordinary differential equations, we examine behaviours of the magnetosonic critical curves, the MHD shock conditions, and various asymptotic solutions. We then construct global semi-complete self-similar MHD solutions using a combination of analytical and numerical means and indicate plausible astrophysical applications of these magnetized flow solutions with or without MHD shocks.Comment: 21 pages, 7 figures, accepted for publication in APS

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

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    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
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