Gravitational collapse and black hole evolution: do holographic black holes eventually "anti-evaporate"?

We study the gravitational collapse of compact objects in the Brane-World. We begin by arguing that the regularity of the five-dimensional geodesics does not allow the energy-momentum tensor of matter on the brane to have (step-like) discontinuities, which are instead admitted in the four-dimensional General Relativistic case, and compact sources must therefore have an atmosphere. Under the simplifying assumption that matter is a spherically symmetric cloud of dust without dissipation, we can find the conditions for which the collapsing star generically ``evaporates'' and approaches the Hawking behavior as the (apparent) horizon is being formed. Subsequently, the apparent horizon evolves into the atmosphere and the back-reaction on the brane metric reduces the evaporation, which continues until the effective energy of the star vanishes. This occurs at a finite radius, and the star afterwards re-expands and ``anti-evaporates''. We clarify that the Israel junction conditions across the brane (holographically related to the matter trace anomaly) and the projection of the Weyl tensor on the brane (holographically interpreted as the quantum back-reaction on the brane metric) contribute to the total energy as, respectively, an ``anti-evaporation'' and an ``evaporation'' term. Concluding, we comment on the possible effects of dissipation and obtain a new stringent bound for the brane tension.Comment: 18 pages in RevTeX4 style, 11 eps figures included. Discussion on the contribution of dissipation and clarifications added, version accepted for publication in Prog. Theor. Phys. Vol. 114, No.

Illegal trafficking and unsustainable waste management in Italy: evidence at the regional level

The presence of organized crime strongly affects sustainable waste management in Italy. In particular, illegal traf cking of waste has become one of the fastest growing areas of crime and one of the most lucrative industries among organized criminal activities, which has now in ltrated both the Italian urban and hazardous waste management cycle. In this study, we aim to investigate the determinants of the illegal traf cking of waste using waste, economic, and enforcement data in a panel analysis over the period 2002-2013. The topic is particularly relevant, given the high heterogeneity across Italian regions which also relates, and eventually leads, to different environmental performances. Our main ndings reveal that, in most Italian regions, enforcement activities do not exert a signi cant deterrence on criminal behaviors; a negative relationship between enforcement and illegal traf cking of waste can be identi ed only for very high levels of enforcement efforts. Moreover, we nd that the major determinants in uencing the rate of illegal traf cking of waste differ between northern-central and southern regions, con rming the existence of a regional dualism. In particular, while in the northern-central area the crime rate is positively related to the level of education and negatively to the adoption of environmentally sound policies, in southern regions the organized activities for illegal traf cking are negatively related to the degree of education attainment and positively to the endowment of waste management plants

Asymptotically AdS brane black holes

We study the possibility of having a static, asymptotically AdS black hole localized on a braneworld with matter fields, within the framework of the Randall and Sundrum scenario. We attempt to look for such a brane black hole configuration by slicing a given bulk spacetime and taking Z_2 symmetry about the slices. We find that such configurations are possible, and as an explicit example, we provide a family of asymptotically AdS brane black hole solutions for which both the bulk and brane metrics are regular on and outside the black hole horizon and brane matter fields are realistic in the sense that the dominant energy condition is satisfied. We also find that our braneworld models exhibit signature change inside the black hole horizon.Comment: 21 pages, 6 figures, RevTex; v2: clarifications added, figures updated, eq.31 corrected, comment on small four dimensional cosmological constant limit added, character size increased, results unchanged. v3: reference added, version accepted in Phys. Rev. D (2006

Holographic bounds and Higgs inflation

In a recently proposed scenario for primordial inflation, where the Standard Model (SM) Higgs boson plays a role of the inflation field, an effective field theory (EFT) approach is the most convenient for working out the consequences of breaking of perturbative unitarity, caused by the strong coupling of the Higgs field to the Ricci scalar. The domain of validity of the EFT approach is given by the ultraviolet (UV) cutoff, which, roughly speaking, should always exceed the Hubble parameter in the course of inflation. On the other hand, applying the trusted principles of quantum gravity to a local EFT demands that it should only be used to describe states in a region larger than their corresponding Schwarschild radius, manifesting thus a sort of UV/IR correspondence. We consider both constraints on EFT, to ascertain which models of the SM Higgs inflation are able to simultaneously comply with them. We also show that if the gravitational coupling evolves with the scale factor, the holographic constraint can be alleviated significantly with minimal set of canonical assumptions, by forcing the said coupling to be asymptotically free.Comment: 9 pages, new material and references added, to appear in PL

Perfil tecnológico de cultivares de trigo brasileiro.

bitstream/item/65470/1/CTAA-DOCUMENTOS-32-TOP-TECNOLOGICO-DE-CULTIVARES-DE-TRIGO-BRASILEIRO-LV-2005-00486.pd

Gravitational collapse and evolution of holographic black holes

Gravitational collapse is analyzed in the Brane-World by arguing that regularity of five-dimensional geodesics require that stars on the brane have an atmosphere. For the simple case of a spherically symmetric cloud of non-dissipating dust, conditions are found for which the collapsing star evaporates and approaches the Hawking behavior as the (apparent) horizon is being formed. The effective energy of the star vanishes at a finite radius and the star afterwards re-expands and "anti-evaporates". Israel junction conditions across the brane (holographically related to the matter trace anomaly) and the projection of the Weyl tensor on the brane (holographically interpreted as the quantum back-reaction on the brane metric) contribute to the total energy as, respectively, an "anti-evaporation" and an "evaporation" term.Comment: 6 pages; Talk given at QG05, Cala Gonone (Italy), September 200

Preferred foliation effects in Quantum General Relativity

We investigate the infrared (IR) effects of Lorentz violating terms in the gravitational sector using functional renormalization group methods similar to Reuter and collaborators. The model we consider consists of pure quantum gravity coupled to a preferred foliation, described effectively via a scalar field with non-standard dynamics. We find that vanishing Lorentz violation is a UV attractive fixed-point of this model in the local potential approximation. Since larger truncations may lead to differing results, we study as a first example effects of additional matter fields on the RG running of the Lorentz violating term and provide a general argument why they are small.Comment: 12 pages, no figures, compatible with published versio