918 research outputs found
On Gauss-Bonnet Curvatures
No full textThe (2k)-th Gauss-Bonnet curvature is a generalization to higher dimensions of the (2k)-dimensional Gauss-Bonnet integrand, it coincides with the usual scalar curvature for k =1. The Gauss-Bonnet curvatures are used in theoretical physics to describe gravity in higher dimensional space times where they are known as the Lagrangian of Lovelock gravity, Gauss-Bonnet Gravity and Lanczos gravity. In this paper we present various aspects of these curvature invariants and review their variational properties. In particular, we discuss natural generalizations of the Yamabe problem, Einstein metrics and minimal submanifolds.This paper is a contribution to the Proceedings of the 2007 Midwest Geometry Conference in honor of Thomas P. Branson. The author would like to thank the referees for useful comments and especially for indicating me the related work of Patterson
On Gauss-Bonnet Curvatures
No full textThe (2k)-th Gauss-Bonnet curvature is a generalization to higher dimensions of the (2k)-dimensional Gauss-Bonnet integrand, it coincides with the usual scalar curvature for k =1. The Gauss-Bonnet curvatures are used in theoretical physics to describe gravity in higher dimensional space times where they are known as the Lagrangian of Lovelock gravity, Gauss-Bonnet Gravity and Lanczos gravity. In this paper we present various aspects of these curvature invariants and review their variational properties. In particular, we discuss natural generalizations of the Yamabe problem, Einstein metrics and minimal submanifolds.This paper is a contribution to the Proceedings of the 2007 Midwest Geometry Conference in honor of Thomas P. Branson. The author would like to thank the referees for useful comments and especially for indicating me the related work of Patterson
Gauss–Bonnet gravitational baryogenesis
No full textAbstractIn this letter we study some variant forms of gravitational baryogenesis by using higher order terms containing the partial derivative of the Gauss–Bonnet scalar coupled to the baryonic current. This scenario extends the well known theory that uses a similar coupling between the Ricci scalar and the baryonic current. One appealing feature of the scenario we study is that the predicted baryon asymmetry during a radiation domination era is non-zero. We calculate the baryon to entropy ratio for the Gauss–Bonnet term and by using the observational constraints we investigate which are the allowed forms of the R+F(G) gravity controlling the evolution. Also we briefly discuss some alternative higher order terms that can generate a non-zero baryon asymmetry, even in the conformal invariance limit
Gauss–Bonnet gravitational baryogenesis
No full text© 2016 The Author(s)In this letter we study some variant forms of gravitational baryogenesis by using higher order terms containing the partial derivative of the Gauss–Bonnet scalar coupled to the baryonic current. This scenario extends the well known theory that uses a similar coupling between the Ricci scalar and the baryonic current. One appealing feature of the scenario we study is that the predicted baryon asymmetry during a radiation domination era is non-zero. We calculate the baryon to entropy ratio for the Gauss–Bonnet term and by using the observational constraints we investigate which are the allowed forms of the R+F(G) gravity controlling the evolution. Also we briefly discuss some alternative higher order terms that can generate a non-zero baryon asymmetry, even in the conformal invariance limit
The second law in four-dimensional Einstein-Gauss-Bonnet gravity
No full textabstract: The topological contribution of a Gauss–Bonnet term in four dimensions to black hole entropy opens up the possibility of a violation of the second law of thermodynamics in black hole mergers. We show, however, that the second law is not violated in the regime where Einstein–Gauss–Bonnet holds as an effective theory and black holes can be treated thermodynamically. For mergers of anti-de Sitter (AdS) black holes, the second law appears to be violated even in Einstein gravity; we argue, however, that the second law holds when gravitational potential energy is taken into account.Copyright IOP Publishing. This is the authors' final, peer-reviewed manuscript. The final version as published can be viewed online at http://dx.doi.org/10.1088/0264-9381/31/15/15500
Static Gauss-Bonnet black holes at large D
No full textWe study the static black holes in the large D dimensions in the Gauss-Bonnet gravity with a cosmological constant, coupled to the Maxewell theory. After integrating the equation of motion with respect to the radial direction, we obtain the effective equations at large D to describe the nonlinear dynamical deformations of the black holes. From the perturbation analysis on the effective equations, we get the analytic expressions of the frequencies for the quasinormal modes of charge and scalar-type perturbations. We show that for a positive Gauss-Bonnet term, the black hole could become unstable only if the cosmological constant is positive, otherwise the black hole is always stable. However, for a negative Gauss-Bonnet term, we find that the black hole could always be unstable. The instability of the black hole depends not only on the cosmological constant and the charge, but also significantly on the Gauss-Bonnet term. Moreover, at the onset of instability there is a non-trivial static zero-mode perturbation, which suggests the existence of a new non-spherically symmetric solution branch. We construct the non-spherical symmetric static solutions of the large D effective equations explicitly.NSFC [11275010, 11335012, 11325522]SCI(E)ARTICLE
Histoire et histoire des religions : Into the Wild
No full textInternational audienceIn the light of her personal scientific path, the author reflects on the founding principles of the history of religions as she conceives and practises it. She highlights five points: the historical, Mediterranean, philological and anthropological, historiographical and comparative dimensions.À la lumière de son parcours scientifique personnel, l’Auteur réfléchit aux principes fondateurs de l’histoire des religions telle qu’elle la conçoit et la pratique ; elle met en avant cinq points : la dimension historique, méditerranéenne, philologique et anthropologique, historiographique et comparative
Hydrodynamics with conserved current via AdS/CFT correspondence in the Maxwell-Gauss-Bonnet gravity
No full textUsing the AdS/CFT correspondence, we study the hydrodynamics with conserved current from the dual Maxwell-Gauss-Bonnet gravity. After constructing the perturbative solution to the first order based on the boosted black brane solution in the bulk Maxwell-Gauss-Bonnet gravity, we extract the stress tensor and conserved current of the dual conformal fluid on its boundary, and also find the effect of the Gauss-Bonnet term on the dual conformal fluid. Our results show that the Gauss-Bonnet term can affect the parameters such as the shear viscosity eta, entropy density s, thermal conductivity kappa and electrical conductivity sigma. However, it does not affect the so-called Wiedemann-Franz law which relates kappa to sigma, while it affects the ratio eta/s. In addition, another interesting result is that eta/s can also be affected by the bulk Maxwell field in our case, which is consistent with some previous results predicted through the Kubo formula. Moreover, the anomalous magnetic and vortical effects by adding the Chern-Simons term are also considered in our case in the Maxwell-Gauss-Bonnet gravity.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000291259200009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)20ARTICLE12null8
Charged Rényi entropies in CFTs with Einstein-Gauss-Bonnet holographic duals
No full textWe calculate the Rényi entropy Sq (μ, λ), for spherical entangling surfaces in CFT’s with Einstein-Gauss-Bonnet-Maxwell holographic duals. Rényi entropies must obey some interesting inequalities by definition. However, for Gauss-Bonnet couplings λ, larger than specific value, but still allowed by causality, we observe a violation of the inequality (formula presented), which is related to the existence of negative entropy black holes, providing interesting restrictions in the bulk theory. Moreover, we find an interesting distinction of the behaviour of the analytic continuation of Sq (μ, λ) for imaginary chemical potential, between negative and non-negative λ. © 2014, The Author(s)
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