tag:blogger.com,1999:blog-5558216287553525802018-03-06T15:41:01.368-08:00General Relativity and Quantum CosmologySite for <a href="http://communitypeerreview.blogspot.com/">Community Peer Review</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.comBlogger7258125tag:blogger.com,1999:blog-555821628755352580.post-73077081845465263052013-08-06T00:15:00.001-07:002013-08-06T00:15:42.347-07:000903.1960 (Horacio E. Camblong et al.)<h2 class="title"><a href="http://arxiv.org/abs/0903.1960">Conformal Tightness of Holographic Scaling in Black Hole Thermodynamics</a> [<a href="http://arxiv.org/pdf/0903.1960">PDF</a>]</h2>Horacio E. Camblong, Carlos R. Ordonez<a name='more'></a><blockquote class="abstract">The near-horizon conformal symmetry of nonextremal black holes is shown to be a mandatory ingredient for the holographic scaling of the scalar-field contribution to the black hole entropy. This conformal tightness is revealed by semiclassical first-principle scaling arguments through an analysis of the multiplicative factors in the entropy due to the radial and angular degrees of freedom associated with a scalar field. Specifically, the conformal SO(2,1) invariance of the radial degree of freedom conspires with the area proportionality of the angular momentum sums to yield a robust holographic outcome.</blockquote>View original: <a href="http://arxiv.org/abs/0903.1960">http://arxiv.org/abs/0903.1960</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-17839588258100249592013-08-06T00:04:00.029-07:002013-08-06T00:04:15.692-07:001305.2963 (Michalis Agathos et al.)<h2 class="title"><a href="http://arxiv.org/abs/1305.2963">Testing general relativity using gravitational waves from binary neutron<br /> stars: Effect of spins</a> [<a href="http://arxiv.org/pdf/1305.2963">PDF</a>]</h2>Michalis Agathos, Walter Del Pozzo, Tjonnie G. F. Li, Chris Van Den Broeck, John Veitch, Salvatore Vitale<a name='more'></a><blockquote class="abstract">We present a Bayesian data analysis pipeline for testing GR using gravitational wave signals from coalescing compact binaries, and in particular binary neutron stars. In this study, we investigate its performance when sources with spins are taken into account.</blockquote>View original: <a href="http://arxiv.org/abs/1305.2963">http://arxiv.org/abs/1305.2963</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-14585274189351371762013-08-06T00:04:00.027-07:002013-08-06T00:04:14.865-07:001308.0635 (Shao-Jun Zhang et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0635">Horizon instability of massless scalar perturbations of an extreme<br /> Reissner-Nordström-AdS black hole</a> [<a href="http://arxiv.org/pdf/1308.0635">PDF</a>]</h2>Shao-Jun Zhang, Qiyuan Pan, Bin Wang, Elcio Abdalla<a name='more'></a><blockquote class="abstract">We study the stability of extreme Reissner-Nordstr\"om-AdS black hole under massless scalar perturbations. We show that the perturbation on the horizon of the extreme Reissner-Nordstr\"om-AdS black hole experiences a power-law decay, instead of an exponential decay as observed in the nonextreme AdS black hole. On the horizon of the extreme Reissner-Nordstr\"om-AdS black hole, the blow up happens at lower order derivative of the scalar field compared with that of the extreme Reissner-Nordstr\"om black hole, which shows that extreme AdS black holes tend to instability in comparison to black holes in asymptotic flat space-times.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0635">http://arxiv.org/abs/1308.0635</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-12765807184878376592013-08-06T00:04:00.025-07:002013-08-06T00:04:13.825-07:001308.0687 (Julian Rennert et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0687">Anisotropic Spinfoam Cosmology</a> [<a href="http://arxiv.org/pdf/1308.0687">PDF</a>]</h2>Julian Rennert, David Sloan<a name='more'></a><blockquote class="abstract">The dynamics of a homogeneous, anisotropic universe are investigated within the context of spinfoam cosmology. Transition amplitudes are calculated for a graph consisting of a single node and three links - the `Daisy graph' - probing the behaviour a classical Bianchi I spacetime. It is shown further how the use of such single node graphs gives rise to a simplification of states such that all orders in the spin expansion can be calculated, indicating that it is the vertex expansion that contains information about quantum dynamics.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0687">http://arxiv.org/abs/1308.0687</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-48284903842682665942013-08-06T00:04:00.023-07:002013-08-06T00:04:12.885-07:001308.0819 (Song He et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0819">Entanglement Temperature in Non-conformal Cases</a> [<a href="http://arxiv.org/pdf/1308.0819">PDF</a>]</h2>Song He, Danning Li, Jun-Bao Wu<a name='more'></a><blockquote class="abstract">Potential reconstruction can be used to find various analytical asymptotical AdS solutions in Einstein dilation system generally. We have generated two simple solutions without physical singularity called zero temperature solutions. We also proposed a numerical way to obtain black hole solution in Einstein dilaton system with special dilaton potential. By using this method, we obtain the corresponding black hole solutions numerically and investigate the thermal stability of the black hole by comparing the free energy of thermal gas and the corresponding black hole. In two groups of non-conformal gravity solutions obtained in this paper, we find that the two thermal gas solutions are more unstable than black hole solutions respectively. Finally, we consider black hole solutions as a thermal state of zero temperature solutions to check that the first thermal dynamical law exists in entanglement system from holographic point of view.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0819">http://arxiv.org/abs/1308.0819</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-17399024693371830002013-08-06T00:04:00.021-07:002013-08-06T00:04:12.203-07:001308.0834 (Omer Farooq et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0834">Observational constraints on non-flat dynamical dark energy cosmological<br /> models</a> [<a href="http://arxiv.org/pdf/1308.0834">PDF</a>]</h2>Omer Farooq, Data Mania, Bharat Ratra<a name='more'></a><blockquote class="abstract">We constrain two non-flat time-evolving dark energy cosmological models by using Hubble parameter data, Type Ia supernova apparent magnitude measurements, and baryonic acoustic oscillation peak length scale observations. The inclusion of space curvature as a free parameter in the analysis results in a significant broadening of the allowed range of values of the parameter that governs the time evolution of the dark energy density in these models. While consistent with the "standard" spatially-flat $\Lambda$CDM cosmological model, these data are also consistent with a range of mildly non-flat, slowly time-varying dark energy models. After marginalizing over all other parameters, these data require the averaged magnitude of the curvature density parameter $|\Omega_{k0}| \lesssim 0.15$ at 1$\sigma$ confidence.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0834">http://arxiv.org/abs/1308.0834</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-22882688662762763042013-08-06T00:04:00.019-07:002013-08-06T00:04:11.531-07:001308.0860 (Luis P. Chimento et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0860">Nonbaryonic dark matter and scalar field coupled with a transversal<br /> interaction plus decoupled radiation</a> [<a href="http://arxiv.org/pdf/1308.0860">PDF</a>]</h2>Luis P. Chimento, Martín G. Richarte<a name='more'></a><blockquote class="abstract">We analyze a universe filled with interacting dark matter, a scalar field accommodated as dark radiation along with dark energy plus a decoupled radiation term within the framework of spatially flat Friedmann-Robertson-Walker (FRW) spacetime. We work in a three-dimensional internal space spanned by the interaction vector and use a transversal interaction $\mathbf{Q_t}$ for solving the source equation in order to find all the interacting component energy densities. We asymptotically reconstruct the scalar field and potential from an early radiation era to the late dominate dark energy one, passing through an intermediate epoch dominated by dark matter. We apply the $\chi^{2}$ method to the updated observational Hubble data for constraining the cosmic parameters, contrast with the Union 2 sample of supernovae, and analyze the amount of dark energy in the radiation era. It turns out that our model fulfills the severe bound of $\Omega_{\rm \phi}(z\simeq 1100)<0.018$ at $2\sigma$ level, is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Atacama Cosmology Telescope and the South Pole Telescope along with the future constraints achievable by Planck and CMBPol experiments, and satisfies the stringent bound $\Omega_{\rm \phi}(z\simeq 10^{10})<0.04$ at $2\sigma$ level in the big-bang nucleosynthesis epoch.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0860">http://arxiv.org/abs/1308.0860</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-62799560227968832532013-08-06T00:04:00.017-07:002013-08-06T00:04:10.749-07:001308.0896 (V. I. Dokuchaev et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0896">Non-orientable wormholes as portals to the mirror world</a> [<a href="http://arxiv.org/pdf/1308.0896">PDF</a>]</h2>V. I. Dokuchaev, Yu. N. Eroshenko<a name='more'></a><blockquote class="abstract">We examine the compatibility of the mirror matter concept with the non-orientable wormholes. If any particle (or classical object) is traversing through the non-orientable wormhole, it turns into a corresponding mirror particle and vice versa. Some astrophysical signatures of the presence of non-orientable wormholes in the Universe are discussed.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0896">http://arxiv.org/abs/1308.0896</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-39415456708189714672013-08-06T00:04:00.015-07:002013-08-06T00:04:09.819-07:001308.0902 (Woei Chet Lim et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0902">Spherically symmetric cosmological spacetimes with dust and radiation -<br /> numerical implementation</a> [<a href="http://arxiv.org/pdf/1308.0902">PDF</a>]</h2>Woei Chet Lim, Marco Regis, Chris Clarkson<a name='more'></a><blockquote class="abstract">We present new numerical cosmological solutions of the Einstein Field Equations. The spacetime is spherically symmetric with a source of dust and radiation approximated as a perfect fluid. The dust and radiation are necessarily non-comoving due to the inhomogeneity of the spacetime. Such a model can be used to investigate non-linear general relativistic effects present during decoupling or big-bang nucleosynthesis, as well as for investigating void models of dark energy with isocurvature degrees of freedom. We describe the full evolution of the spacetime as well as the redshift and luminosity distance for a central observer. After demonstrating accuracy of the code, we consider a few example models, and demonstrate the sensitivity of the late time model to the degree of inhomogeneity of the initial radiation contrast.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0902">http://arxiv.org/abs/1308.0902</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-91202637457712396052013-08-06T00:04:00.013-07:002013-08-06T00:04:08.869-07:001308.0978 (J. Petri)<h2 class="title"><a href="http://arxiv.org/abs/1308.0978">General-relativistic electromagnetic fields around a slowly rotating<br /> neutron star: stationary vacuum solutions</a> [<a href="http://arxiv.org/pdf/1308.0978">PDF</a>]</h2>J. Petri<a name='more'></a><blockquote class="abstract">Pulsars are thought to be highly magnetized rotating neutron stars accelerating charged particles along magnetic field lines in their magnetosphere and visible as pulsed emission from the radio wavelength up to high energy X-rays and gamma-rays. Being highly compact objects with compactness close to $\Xi = R_s/R\approx0.5$, where $\Rs=2\,G\,M/c^2$ is the Schwarzschild radius and $\{M,R\}$ the mass and radius of the neutron star, general-relativistic effects become important close to their surface. This is especially true for the polar caps where radio emission is supposed to emanate from, leading to well defined signatures such as linear and circular polarization. In this paper, we derive a general formalism to extend to general relativity the Deutsch field solution valid in vacuum space. Thanks to a vector spherical harmonic expansion of the electromagnetic field, we are able to express the solution to any order in the spin parameter $\Omega$ of the compact object. We hope this analysis to serve as a benchmark to test numerical codes used to compute black hole and neutron star magnetospheres.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0978">http://arxiv.org/abs/1308.0978</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-2076218231577258022013-08-06T00:04:00.011-07:002013-08-06T00:04:07.899-07:001308.0988 (Kari Enqvist et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0988">Binary systems in Palatini-f(R) gravity</a> [<a href="http://arxiv.org/pdf/1308.0988">PDF</a>]</h2>Kari Enqvist, Tomi Koivisto, Hannu J. Nyrhinen<a name='more'></a><blockquote class="abstract">We consider compact binary systems in f(R) gravity theories in the Palatini approach and calculate the post-Newtonian parameters to the 1.5PN order using the method of Direct Integration of the Relaxed Einstein equations (DIRE). The Palatini-type modifications of gravity can be formulated as Einsteins gravity with modified response to matter sources, and it is shown in detail how to treat these correctly within the DIRE formalism. Our results explicitly confirm the expectation that for binary black holes the new effects can be absorbed into redefinitions of the binary masses, rendering such systems observationally identical to general relativity.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0988">http://arxiv.org/abs/1308.0988</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-49894906518107677782013-08-06T00:04:00.009-07:002013-08-06T00:04:06.564-07:001308.1007 (Gerard 't Hooft)<h2 class="title"><a href="http://arxiv.org/abs/1308.1007">The Fate of the Quantum</a> [<a href="http://arxiv.org/pdf/1308.1007">PDF</a>]</h2>Gerard 't Hooft<a name='more'></a><blockquote class="abstract">Although the suspicion that quantum mechanics is emergent has been lingering for a long time, only now we begin to understand how a bridge between classical and quantum mechanics might be squared with Bell's inequalities and other conceptual obstacles. Here, it is shown how mappings can be formulated that relate quantum systems to classical systems. By generalizing these ideas, one gets quite general models in which quantum mechanics and classical mechanics can merge. It is helpful to have some good model examples such as string theory. It is suggested that notions such as 'super determinism' and 'conspiracy' should be looked at much more carefully than in the, by now, standard arguments.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1007">http://arxiv.org/abs/1308.1007</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-28357947301577845562013-08-06T00:04:00.007-07:002013-08-06T00:04:05.554-07:001308.1012 (Yasha Neiman)<h2 class="title"><a href="http://arxiv.org/abs/1308.1012">A look at area Regge calculus</a> [<a href="http://arxiv.org/pdf/1308.1012">PDF</a>]</h2>Yasha Neiman<a name='more'></a><blockquote class="abstract">Area Regge calculus is a candidate theory of simplicial gravity, based on the Regge action with triangle areas as the dynamical variables. It is characterized by metric discontinuities and vanishing deficit angles. Area Regge calculus arises in the large-spin limit of the Barrett-Crane spinfoam model, but not in the newer EPRL/FK model. We address the viability of area Regge calculus as a discretization of General Relativity. We argue that when all triangles are spacelike and all tetrahedra have the same signature, non-trivial solutions of the area calculus are associated with a nonzero Ricci scalar. Our argument rests on a seemingly natural regularization of the metric discontinuities. It rules out the Euclidean area calculus, as well as the Lorentzian sector with all tetrahedra spacelike - the two setups usually considered in spinfoam models. On the other hand, we argue that the area calculus has attractive properties from the point of view of finite-region observables in quantum gravity.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1012">http://arxiv.org/abs/1308.1012</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-85351351636013752062013-08-06T00:04:00.005-07:002013-08-06T00:04:04.590-07:001308.1052 (Steven Duplij)<h2 class="title"><a href="http://arxiv.org/abs/1308.1052">Formulation of singular theories in a partial Hamiltonian formalism<br /> using a new bracket and multi-time dynamics</a> [<a href="http://arxiv.org/pdf/1308.1052">PDF</a>]</h2>Steven Duplij<a name='more'></a><blockquote class="abstract">A formulation of singular classical theories (determined by degenerate Lagrangians) without constraints is presented. A partial Hamiltonian formalism in the phase space having an initially arbitrary number of momenta (which can be smaller than the number of velocities) is proposed. The equations of motion become first-order differential equations, and they coincide with those of multi-time dynamics, if a certain condition is imposed. In a singular theory, this condition is fulfilled in the case of the coincidence of the number of generalized momenta with the rank of the Hessian matrix. The noncanonical generalized velocities satisfy a system of linear algebraic equations, which allows an appropriate classification of singular theories (gauge and nongauge). A new antisymmetric bracket (similar to the Poisson bracket) is introduced, which describes the time evolution of physical quantities in a singular theory. The origin of constraints is shown to be a consequence of the (unneeded in our formulation) extension of the phase space. In this case the new bracket transforms into the Dirac bracket. Quantization is briefly discussed.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1052">http://arxiv.org/abs/1308.1052</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-32289068795639313592013-08-06T00:04:00.003-07:002013-08-06T00:04:03.470-07:001308.1076 (Alcides Garat)<h2 class="title"><a href="http://arxiv.org/abs/1308.1076">The equivalence between local inertial frames and electromagnetic gauge<br /> in Einstein-Maxwell theories</a> [<a href="http://arxiv.org/pdf/1308.1076">PDF</a>]</h2>Alcides Garat<a name='more'></a><blockquote class="abstract">We are going to prove that locally the inertial frames and gauge states of the electromagnetic field are equivalent. This proof will be valid for Einstein-Maxwell theories in four-dimensional Lorentzian spacetimes. Use will be made of theorems proved in a previous manuscript. These theorems state that locally the group of electromagnetic gauge transformations is isomorphic to the local Lorentz transformations of a special set of tetrad vectors. The tetrad that locally and covariantly diagonalizes any non-null electromagnetic stress-energy tensor. Two isomorphisms, one for each plane defined locally by two separate sets of two vectors each. In particular, we are going to use the plane defined by the timelike and one spacelike vector, plane or blade one. These results will be extended to any tetrad that results in a local Lorentz transformation of the special tetrad that locally and covariantly diagonalizes the stress-energy tensor.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1076">http://arxiv.org/abs/1308.1076</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-60812226324053987992013-08-06T00:04:00.001-07:002013-08-06T00:04:02.654-07:001308.1079 (Holger Mueller et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.1079">Matter wave interferometry for antimatter gravity measurements</a> [<a href="http://arxiv.org/pdf/1308.1079">PDF</a>]</h2>Holger Mueller, Paul Hamilton, Andrey Zhmoginov, Francis Robicheaux, Joel Fajans, Jonathan Wurtele<a name='more'></a><blockquote class="abstract">We describe a light-pulse atom interferometer that is suitable for any species of atom and even for electrons and positrons, in particular for testing the Einstein equivalence principle with antihydrogen. The design obviates the need for resonant lasers through far-off resonant Bragg beam splitters and makes efficient use of scarce atoms by magnetic confinement and atom recycling. We expect to reach an accuracy better than 1% in an initial experiment which can be improved to the part-per million level.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1079">http://arxiv.org/abs/1308.1079</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-55507060002251440132013-08-05T00:03:00.019-07:002013-08-05T00:03:10.149-07:001112.0817 (Martin Maria Kovár)<h2 class="title"><a href="http://arxiv.org/abs/1112.0817">A New Causal Topology and Why the Universe is Co-compact</a> [<a href="http://arxiv.org/pdf/1112.0817">PDF</a>]</h2>Martin Maria Kovár<a name='more'></a><blockquote class="abstract">We show that there exists a canonical topology, naturally connected with the causal site of J. D. Christensen and L. Crane, a pointless algebraic structure motivated by quantum gravity. Taking a causal site compatible with Minkowski space, on every compact subset our topology became a reconstruction of the original topology of the spacetime (only from its causal structure). From the global point of view, the reconstructed topology is the de Groot dual or co-compact with respect to the original, Euclidean topology. The result indicates that the causality is the primary structure of the spacetime, carrying also its topological information.</blockquote>View original: <a href="http://arxiv.org/abs/1112.0817">http://arxiv.org/abs/1112.0817</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-3076000222176170002013-08-05T00:03:00.017-07:002013-08-05T00:03:09.041-07:001308.0325 (Adnan Aslam et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0325">Noether gauge symmetry for the Bianchi type I model in f(T) gravity</a> [<a href="http://arxiv.org/pdf/1308.0325">PDF</a>]</h2>Adnan Aslam, Mubasher Jamil, Ratbay Myrzakulov<a name='more'></a><blockquote class="abstract">In this paper, we present the Noether symmetries of a class of the Bianchi type I anisotropic model in the context of f(T) gravity. By solving the system of equations obtained from the Noether symmetry condition, we obtain the form of f(T) as a teleparallel form. This analysis shows that teleparallel gravity has the maximum number of Noether symmetries. We derive the symmetry generators and show that there are five kinds of symmetries, including time and scale invariance under metric coefficients. We classify the symmetries and we obtain the corresponding invariants.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0325">http://arxiv.org/abs/1308.0325</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-25072241217213055602013-08-05T00:03:00.015-07:002013-08-05T00:03:07.998-07:001308.0331 (Paul McFadden)<h2 class="title"><a href="http://arxiv.org/abs/1308.0331">On the power spectrum of inflationary cosmologies dual to a deformed CFT</a> [<a href="http://arxiv.org/pdf/1308.0331">PDF</a>]</h2>Paul McFadden<a name='more'></a><blockquote class="abstract">We analyse slow-roll inflationary cosmologies that are holographically dual to a three-dimensional conformal field theory deformed by a nearly marginal scalar operator. We show the cosmological power spectrum is inversely proportional to the spectral density associated with the 2-point function of the trace of the stress tensor in the deformed CFT. Computing this quantity using second-order conformal perturbation theory, we obtain a holographic power spectrum in exact agreement with the expected inflationary power spectrum to second order in slow roll.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0331">http://arxiv.org/abs/1308.0331</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-5815607424561837392013-08-05T00:03:00.013-07:002013-08-05T00:03:07.369-07:001308.0341 (Peter Arnold et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0341">Spin 1/2 quasinormal mode frequencies in Schwarzschild-AdS spacetime</a> [<a href="http://arxiv.org/pdf/1308.0341">PDF</a>]</h2>Peter Arnold, Phillip Szepietowski<a name='more'></a><blockquote class="abstract">We find the asymptotic formula for quasinormal mode frequencies omega_n of the Dirac equation in a Schwarzschild-AdS_D background in space-time dimension D > 3, in the large black-hole limit appropriate to many applications of the AdS/CFT correspondence. By asymptotic, we mean large overtone number n with everything else held fixed, and we find the O(n^0) correction to the known leading O(n) behavior of omega_n. The result has the schematic form omega_n =~ n Delta(omega) + A ln(n) + B, where Delta(omega) and A are constants and B depends logarithmically on the (D-2)-dimensional spatial momentum k parallel to the horizon. We show that the asymptotic result agrees well with exact quasinormal mode frequencies computed numerically.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0341">http://arxiv.org/abs/1308.0341</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-46012938688978925092013-08-05T00:03:00.011-07:002013-08-05T00:03:06.608-07:001308.0373 (A. Hees et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0373">How to test SME with space missions ?</a> [<a href="http://arxiv.org/pdf/1308.0373">PDF</a>]</h2>A. Hees, B. Lamine, C. Le Poncin-Lafitte, P. Wolf<a name='more'></a><blockquote class="abstract">In this communication, we focus on possibilities to constrain SME coefficients using Cassini and Messenger data. We present simulations of radioscience observables within the framework of the SME, identify the linear combinations of SME coefficients the observations depend on and determine the sensitivity of these measurements to the SME coefficients. We show that these datasets are very powerful for constraining SME coefficients.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0373">http://arxiv.org/abs/1308.0373</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-9727839968075974142013-08-05T00:03:00.009-07:002013-08-05T00:03:04.624-07:001308.0394 (Pierre Fromholz et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0394">The Schwarzschild metric: It's the coordinates, stupid!</a> [<a href="http://arxiv.org/pdf/1308.0394">PDF</a>]</h2>Pierre Fromholz, Eric Poisson, Clifford M. Will<a name='more'></a><blockquote class="abstract">Every general relativity textbook emphasizes that coordinates have no physical meaning. Nevertheless, a coordinate choice must be made in order to carry out real calculations, and that choice can make the difference between a calculation that is simple and one that is a mess. We give a concrete illustration of the maxim that "coordinates matter" using the exact Schwarzschild solution for a vacuum, static, spherical spacetime. We review the standard textbook derivation, Schwarzschild's original 1916 derivation, and a derivation using the Landau-Lifshitz formulation of the Einstein field equations. The last derivation is much more complicated, has one aspect for which we have been unable to find a solution, and gives an explicit illustration of the fact that the Schwarzschild geometry can be described in infinitely many coordinate systems.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0394">http://arxiv.org/abs/1308.0394</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-48916683930310268102013-08-05T00:03:00.007-07:002013-08-05T00:03:03.610-07:001308.0523 (Rampei Kimura et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0523">Derivative interactions in de Rham-Gabadadze-Tolley massive gravity</a> [<a href="http://arxiv.org/pdf/1308.0523">PDF</a>]</h2>Rampei Kimura, Daisuke Yamauchi<a name='more'></a><blockquote class="abstract">We investigate a possibility of new massive gravity theory with derivative interactions as an extension of de Rham-Gabadadze-Tolley massive gravity. We found the most general Lagrangian of derivative interactions whose cutoff energy scale is $\Lambda_3$, which is consistent with de Rham-Gabadadze-Tolley massive gravity. Surprisingly, this infinite number of derivative interactions can be resummed with the same method in de Rham-Gabadadze-Tolley massive gravity, and remaining interactions contain only two parameters. We show that the equations of motion for scalar and tensor modes in the decoupling limit contain 4th derivative with respect to space-time, which implies the appearance of ghosts at $\Lambda_3$. We claim that consistent derivative interactions in de Rham-Gabadadze-Tolley massive gravity has a mass scale $M$, which is much smaller than the Planck mass $M_{\rm Pl}$.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0523">http://arxiv.org/abs/1308.0523</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-61836377603833691212013-08-05T00:03:00.005-07:002013-08-05T00:03:02.616-07:001308.0534 (Joseph Elliston)<h2 class="title"><a href="http://arxiv.org/abs/1308.0534">Observable predictions of generalised inflationary scenarios</a> [<a href="http://arxiv.org/pdf/1308.0534">PDF</a>]</h2>Joseph Elliston<a name='more'></a><blockquote class="abstract">Inflation is an early period of accelerated cosmic expansion, thought to be sourced by high energy physics. A key task today is to use the influx of increasingly precise observational data to constrain the plethora of inflationary models suggested by fundamental theories of interactions. This requires a robust theoretical framework for quantifying the predictions of such models; helping to develop such a framework is the aim of this thesis. We provide the first complete quantization of subhorizon perturbations for the well-motivated class of multi-field inflationary models with a non-trivial field metric, which we show may yield interesting signatures in the bispectrum of the Cosmic Microwave Background (CMB). The subsequent evolution of perturbations in the superhorizon epoch is then considered, via a covariant extension of the transport formalism. To develop intuition about the relationship between inflationary dynamics and the evolution of cosmic observables, we investigate analytic approximations of superhorizon perturbation evolution. The validity of these analytic results is contingent on reaching a state of adiabaticity which we discuss and illustrate in depth. We then apply our analytic methods to elucidate the types of inflationary dynamics that lead to an enhanced CMB non-Gaussianity, both in its bispectrum and trispectrum. In addition to deriving a number of new simple relations between the non-Gaussianity parameters, we explain dynamically how and why different shapes of inflationary potential lead to particular observational signatures. Candidate theories of high energy physics such as low energy effective string theory also motivate single-field modifications to the Einstein-Hilbert action. We show how a range of such corrections allow for consistency of single-field chaotic inflationary models that are otherwise in tension with observational data.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0534">http://arxiv.org/abs/1308.0534</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-555821628755352580.post-77241665148873653732013-08-05T00:03:00.003-07:002013-08-05T00:03:01.618-07:001308.0548 (Jose Luis Blazquez-Salcedo et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0548">Sequences of extremal radially excited rotating black holes</a> [<a href="http://arxiv.org/pdf/1308.0548">PDF</a>]</h2>Jose Luis Blazquez-Salcedo, Jutta Kunz, Francisco Navarro-Lerida, Eugen Radu<a name='more'></a><blockquote class="abstract">In Einstein-Maxwell-Chern-Simons theory the extremal Reissner-Nordstr\"om solution is no longer the single extremal solution with vanishing angular momentum, when the Chern-Simons coupling constant reaches a critical value. Instead a whole sequence of rotating extremal J=0 solutions arises, labeled by the node number of the magnetic U(1) potential. Associated with the same near horizon solution, the mass of these radially excited extremal solutions converges to the mass of the extremal Reissner-Nordstr\"om solution. On the other hand, not all near horizon solutions are also realized as global solutions</blockquote>View original: <a href="http://arxiv.org/abs/1308.0548">http://arxiv.org/abs/1308.0548</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0