1539587
Noncommutative Geometry and Classical Orbits of Particles in a Central Force Potential
We investigate the effect of the noncommutative geometry on the classical orbits of particles in a central force potential The relation is implemented through the modified commutation relations [xi,xj] = iθij. Comparison with observations places severe constraints on the value of the noncommutativity parameter.
11749680
The Decay of singlet scalar dark matter to unparticle and photon
We consider the unparticle physics introduced by Georgi and show that if the standard model is extended to include a singlet scalar as a dark matter candidate, there is a channel which leads to its decay to photon and unparticle. We calculate the decay rate for this new channel and find a lower bound on unparticle physics scale by demanding the stability of this candidate of the dark matter.
118841749
Counterterm method in Lovelock theory and horizonless solutions in dimensionally continued gravity
In this paper we, first, generalize the quasilocal definition of the stress-energy tensor of Einstein gravity to the case of Lovelock gravity, by introducing the tensorial form of surface terms that make the action well-defined. We also introduce the boundary counterterm that removes the divergences of the action and the conserved quantities of the solutions of Lovelock gravity with flat boundary at constant t and r. Second, we obtain the metric of spacetimes generated by brane sources in dimensionally continued gravity through the use of Hamiltonian formalism, and show that these solutions have no curvature singularity and no horizons, but have conic singularity. We show that these asymptotically AdS spacetimes which contain two fundamental constants are complete. Finally we compute the conserved quantities of these solutions through the use of the counterterm method introduced in the first part of the paper.
119241183
Magnetic branes in third order Lovelock-Born-Infeld gravity
Considering both the nonlinear invariant terms constructed by the electromagnetic field and the Riemann tensor in gravity action, we obtain a new class of (n+1)-dimensional magnetic brane solutions in third order Lovelock-Born-Infeld gravity. This class of solutions yields a spacetime with a longitudinal nonlinear magnetic field generated by a static source. These solutions have no curvature singularity and no horizons but have a conic geometry with a deficit angle {delta}. We find that, as the Born-Infeld parameter decreases, which is a measure of the increase of the nonlinearity of the electromagnetic field, the deficit angle increases. We generalize this class of solutions to the case of spinning magnetic solutions and find that, when one or more rotation parameters are nonzero, the brane has a net electric charge which is proportional to the magnitude of the rotation parameters. Finally, we use the counterterm method in third order Lovelock gravity and compute the conserved quantities of these spacetimes. We found that the conserved quantities do not depend on the Born-Infeld parameter, which is evident from the fact that the effects of the nonlinearity of the electromagnetic fields on the boundary at infinity are wiped away. We also find that the properties ofmore » our solution, such as deficit angle, are independent of Lovelock coefficients.« less
122997784
Corrected Hawking Tunneling Radiation in the Higher Dimensional Reissner-Nordström Black Hole
Based on the generalized uncertainty principle, in which the quantum gravitational effects are properly taken in to account, the corrected Bekenstein-Hawking entropy of the higher dimensional Reissner-Nordström black hole, up to the square order of Planck length, has been calculated. Using the corrected entropy, the black hole radiation probability has been calculated in the tunneling formalism, which is corrected up to the same order of the Planck length and a generalized quantum tunneling through the event horizon of the black hole is obtained.
123162229
Generalized uncertainty principle, modified dispersion relation and Reissner–Nordström black hole tunneling radiation
Abstract The Parikh–Kraus–Wilczek tunneling proposal of black hole tunneling radiation is considered. Reissner–Nordstrom black hole thermodynamics is studied according to the generalized uncertainty principle and the modified dispersion relation analysis. It is shown that entropy, temperature and the original Parikh–Kraus–Wilczek calculation of the black hole tunneling probability receive new corrections. The results of these two alternative approaches are identical if one uses the suitable expansion coefficients.