261 research outputs found

    Hawking Radiation of Black p-Branes from Gravitational Anomaly

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    We investigate the Hawking radiation of black pp-branes of superstring theories using the method of anomaly cancelation, specially, we use the method of [S. Iso, H. Umetsu and F. Wilczek, {\sl Phys. Rev. Lett.} {\bf 96}, 151302 (2006); {\sl Phys. Rev. D} {\bf 74}, 044017 (2006)]. The metrics of black pp-branes are spherically symmetric, but not the Schwarzschild type. In order to simplify the calculation, we first make a coordinate transformation to transform the metric to the Schwarzschild type. Then we calculate its energy-momentum flux from the method of anomaly cancelation of the above mentioned references. The obtained energy-momentum flux is equal to a black body radiation, the thermodynamic temperature of the radiation is equal to its Hawking temperature. And we find that the results are not changed for the original non-Schwarzschild type spherically symmetric metric.Comment: 19 pages Latex, some mistakes correcte

    (2E,6E)-2,6-Difurfurylidenecyclo­hexa­none

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    The complete mol­ecule of the title compound, C16H14O3, is generated by crystallographic mirror symmetry, with two C atoms and one O atom lying on the mirror plane. The mol­ecule adopts an E configuration about the C=C bond and the dihedral angle between the furan rings is 16.1 (2)°

    Causality in Non-Commutative Quantum Field Theories

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    We study causality in non-commutative quantum field theory with a space-space non-commutativity. We employ the S-operator approach of Bogoliubov-Shirkov(BS). We generalize the BS criterion of causality to the noncommutative theory. The criterion to test causality leads to a nonzero difference between T*-product and T-product as a condition of causality violation for a spacelike separation. We discuss two examples; one in a scalar theory and one in the Yukawa theory. In particular, in the context of a non-commutative Yukawa theory, with the interaction Lagrangian ψˉ(x)ψ(x)ϕ(x)\bar{\psi}(x)\star\psi(x)\star\phi(x), is observed to be causality violating even in case of space-space noncommutativity for which \theta^{0i}=0. \Comment: 18 pages, LaTeX; A few changes in sections 3.2,3.3 and

    Chlorido(5-formyl-2-hydroxy­phenyl-κC 1)mercury(II)

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    In the planar (r.m.s. deviation = 0.027 Å) title compound, [Hg(C7H5O2)Cl], the HgII atom shows a typical linear coordination by a C atom of the benzene ring and a Cl atom. Inter­molecular O—H⋯O hydrogen bonds are present in the crystal structure, resulting in chains propagating along the b axis. The crystal studied was a non-merohedral twin, with a twin ratio of 0.802 (2):0.198 (2)
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