445,598 research outputs found

    Nucleosynthesis in Supernovae

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    Core collapse supernovae are dominated by energy transport from neutrinos. Therefore, some supernova properties could depend on symetries and features of the standard model weak interactions. The cross section for neutrino capture is larger than that for antineutrino capture by one term of order the neutrino energy over the nucleon mass. This reduces the ratio of neutrons to protons in the ν\nu-driven wind above a protoneutron star by approximately 20 % and may significantly hinder r-process nucleosynthesis.Comment: 5 pages, deleted "high brow stuff" on charge conjugation for referee, Phys. Rev. Lett. in pres

    Charge Conjugation Violation in Supernovae and The Neutron Shortage for R-Process Nucelosynthesis

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    Core collapse supernovae are dominated by energy transport from neutrinos. Therefore, some supernova properties could depend on symetries and features of the standard model weak interactions. The cross section for neutrino capture is larger than that for antineutrino capture by one term of order the neutrino energy over the nucleon mass. This reduces the ratio of neutrons to protons in the ν\nu-driven wind above a protoneutron star by approximately 20 % and may significantly hinder r-process nucleosynthesis.Comment: Proceedings of Intersections Conference, Qube

    Enhanced collectivity in neutron-deficient Sn isotopes in energy functional based collective Hamiltonian

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    The low-lying collective states in Sn isotopes are studied by a five-dimensional collective Hamiltonian with parameters determined from the triaxial relativistic mean-field calculations using the PC-PK1 energy density functional. The systematics for both the excitation energies of 21+2^+_1 states and B(E2;01+21+)B(E2;0^+_1\to 2^+_1) values are reproduced rather well, in particular, the enhanced E2 transitions in the neutron-deficient Sn isotopes with N<66. We show that the gradual degeneracy of neutron levels 1g7/2 and 2d5/2 around the Fermi surface leads to the increase of level density and consequently the enhanced paring correlations from N=66 to 58. It provokes a large quadrupole shape fluctuation around the spherical shape, and leads to an enhanced collectivity in the isotopes around N=58.Comment: 5 pages, 4 figures, accepted for publication in Physics Letters

    On the (non)rigidity of the Frobenius Endomorphism over Gorenstein Rings

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    It is well-known that for a large class of local rings of positive characteristic, including complete intersection rings, the Frobenius endomorphism can be used as a test for finite projective dimension. In this paper, we exploit this property to study the structure of such rings. One of our results states that the Picard group of the punctured spectrum of such a ring RR cannot have pp-torsion. When RR is a local complete intersection, this recovers (with a purely local algebra proof) an analogous statement for complete intersections in projective spaces first given in SGA and also a special case of a conjecture by Gabber. Our method also leads to many simply constructed examples where rigidity for the Frobenius endomorphism does not hold, even when the rings are Gorenstein with isolated singularity. This is in stark contrast to the situation for complete intersection rings. Also, a related length criterion for modules of finite length and finite projective dimension is discussed towards the end.Comment: Minor changes in Example 2.2 and Theorem 2.9. Conjecture 1.2 was added

    Tinodes species (Trichoptera: Psychomyiidae) from The People's Republic of China

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    Five species of the genus Tinodes from the People's Republic of China are described and re-described, among which four species are new to science. A key to males of all five species and a key to females of two species are given

    Soft Gluon Resummation Effects in Single Graviton Production at the CERN Large Hadron Collider in the Randall-Sundrum Model

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    We study QCD effects in single graviton production at the CERN Large Hadron Collider (LHC) in the Randall-Sundrum (RS) Model. We present in detail the complete next-to-leading order (NLO) QCD corrections to the inclusive total cross sections. The NLO QCD corrections enhance significantly the total cross sections and decrease efficiently the dependence of the total cross sections on the factorization and renormalization scales. We also examine the uncertainty of the total cross sections due to the parton distribution function (PDF) uncertainties. For the differential cross sections on the transverse momentum (qTq_T) of the graviton, within the CSS resummation formalism, we resum the logarithmically-enhanced terms at small qTq_T to all orders up to NLO logatithmic accuracy. Combined with the fixed order calculations, we give consistent predictions for both small qTq_T and large qTq_T.Comment: 26 pages, 13 figures; minor changes and misprints corrected; version to appear in PR

    Polypiectropus species (Trichoptera: Polycentropodidae) from China : with consideration of their phylogeny

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    Six species of the genus Polyplectropns are recorded from the People's Republic of China. All the species are new to science. A key to the males is given. The larva of Polyplectropns nanjingensis sp. nov. is illustrated. The phylogenetic relationships among these species and with Polyplectropns species of the New World are discussed
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