118596724
Generalized gravitational entropy of probe branes: flavor entanglement holographically
A bstractThe notion of generalized gravitational entropy introduced by Lewkowycz and Maldacena allows, via the AdS/CFT correspondence, to calculate CFT entanglement entropies. We adapt the method to the case where flavor branes are present and treated in the probe approximation. This allows to calculate the leading flavor correction to the CFT entanglement entropy from the on-shell action of the probe, while dealing with the backreaction is avoided entirely and from the outset. As an application we give concise derivations for the contribution of massless and massive flavor degrees of freedom to the entanglement entropy in $ \mathcal{N} $ = 4 SYM theory.
118522139
Spacetime noncommutativity in models with warped extradimensions
We construct consistent noncommutative (NC) deformations of the Randall-Sundrum spacetime that solve the NC Einstein equations with a non-trivial Poisson tensor depending on the fifth coordinate. In a class of these deformations where the Poisson tensor is exponentially localized on one of the branes (the NC-brane), we study the effects on bulk particles in terms of Lorentz-violating operators induced by NC-brane interactions. We sketch two models in which massive bulk particles mediate NC effects to an almost-commutative SM-brane, such that observables at high energy colliders are enhanced with respect to low energy and astrophysical observables.
118599677
High energy improved scalar quantum field theory from noncommutative geometry without UV/IR-mixing
We consider an interacting scalar quantum field theory on noncommutative Euclidean space. We implement a family of noncommutative deformations, which – in contrast to the well known Moyal-Weyl deformation – lead to a theory with modified kinetic term, while all local potentials are unaffected by the deformation. We show that our models, in particular, include propagators with anisotropic scaling z = 2 in the ultraviolet (UV). For a � 4 -theory on our noncommutative space we obtain an improved UV behaviour at the one-loop level and the absence of UV/IR-mixing and of the Landau pole.
118653300
Quantization of the massive gravitino on FRW spacetimes
Institut fur Theoretische Physik und AstrophysikUniversitat Wurzbur g, Am Hubland, 97074 Wurzbur g, Germany(Dated: September 15, 2011)In this article we study the quantization and causal properties of a massive spin 3=2 Rarita-Schwinger eld on spatially at Friedmann-Robertson-Walker (FRW) spacetimes. We constructZuckerman’s universal conserved current and prove that it leads to a positive de nite inner producton solutions of the eld equation. Based on this inner product, we quantize the Rarita-Schwinger eld in terms of a CAR-algebra. The transversal and longitudinal parts constituting the independenton-shell degrees of freedom decouple. We nd a Dirac-type equation for the transversal polarizations,ensuring a causal propagation. The equation of motion for the longitudinal part is also of Dirac-type,but with respect to an ‘e ective metric’. We obtain that for all four-dimensional FRW solutions witha matter equation of state p= !ˆand !2( 1;1] the light cones of the e ective metric are morenarrow than the standard cones, which are recovered for the de Sitter case != 1. In particular,this shows that the propagation of the longitudinal part, although non-standard for !6= 1, iscompletely causal in cosmological constant, dust and radiation dominated universes.
119110593
Coarse-grained cosmological perturbation theory: stirring up the dust model
We study the effect of coarse-graining the dynamics of a pressureless selfgravitating fluid (coarse-grained dust) in the context of cosmological perturbation theory, both in the Eulerian und Lagrangian framework. We obtain recursion relations for the Eulerian perturbation kernels of the coarse-grained dust model by relating them to those of the standard pressureless fluid model. The effect of the coarse-graining is illustrated by means of power and cross spectra for density and velocity that are computed up to 1-loop order. In particular, the large scale vorticity power spectrum that arises naturally from a mass-weighted velocity is derived from first principles. We find qualitatively good agreement of the magnitude, shape and spectral index of the vorticity power spectrum with recent measurements from N-body simulations and results from the effective field theory of large scale structure. To lay the ground for applications in the context of Lagrangian perturbation theory we finally describe how the kernels obtained in Eulerian space can be mapped to Lagrangian ones.
119242094
Newton to Einstein — dust to dust
We investigate the relation between the standard Newtonian equations for a pressureless fluid (dust) and the Einstein equations in a double expansion in small scales and small metric perturbations. We find that parts of the Einstein equations can be rewritten as a closed system of two coupled differential equations for the scalar and transverse vector metric perturbations in Poisson gauge. It is then shown that this system is equivalent to the Newtonian system of continuity and Euler equations. Brustein and Riotto (2011) conjectured the equivalence of these systems in the special case where vector perturbations were neglected. We show that this approach does not lead to the Euler equation but to a physically different one with large deviations already in the 1-loop power spectrum. We show that it is also possible to consistently set to zero the vector perturbations which strongly constrains the allowed initial conditions, in particular excluding Gaussian ones such that inclusion of vector perturbations is inevitable in the cosmological context. In addition we derive nonlinear equations for the gravitational slip and tensor perturbations, thereby extending Newtonian gravity of a dust fluid to account for nonlinear light propagation effects and dust-induced gravitational waves.