DSpace Collection:
http://hdl.handle.net/10071/5554
Thu, 20 Aug 2020 16:57:51 GMT2020-08-20T16:57:51ZCharged black holes in Einsteinian cubic gravity and nonuniqueness
http://hdl.handle.net/10071/20617
Title: Charged black holes in Einsteinian cubic gravity and nonuniqueness
Authors: Frassino, A. M.; Rocha, J. V.
Abstract: Black holes are the simplest objects in the Universe. They correspond to extreme deformations of spacetime geometry and can exist even devoid of matter. In general relativity, (electro)vacuum black holes are uniquely determined by their mass, charge, and angular momentum. This feature follows from a uniqueness theorem, which can be evaded if one considers higher dimensions or matter fields coupled to gravity. Here we find that Einsteinian cubic gravity, a well-motivated modification of Einstein gravity that includes third-order curvature corrections in accordance with low-energy effective theory expectations, admits black hole solutions with charge greater than mass, when minimally coupled to a Maxwell field. Moreover, we find that, in this regime, there can be two asymptotically flat black holes with the same charge and mass, posing the first example of vacuum black hole nonuniqueness in four dimensions that is free from pathologies. Examination of these black hole’s thermodynamics reveals that when two branches coexist only the larger black hole is thermodynamically stable, while the smaller branch has negative specific heat. Einsteinian cubic gravity unveils two further surprising features. The charged black holes do not possess an inner horizon, in contrast with the usual Reissner-Nordström spacetime, thus avoiding the need to resort to strong cosmic censorship to uphold determinism. In addition to black holes, there exists a one-parameter family of naked singularity spacetimes sharing the same mass and charge as the former, but not continuously connected with them. These naked singularities exist in the under-extremal regime, being present even in pure (uncharged) Einsteinian cubic gravity.Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10071/206172020-01-01T00:00:00ZFive-dimensional cohomological localization and squashed q-deformations of two-dimensional Yang-Mills theory
http://hdl.handle.net/10071/20609
Title: Five-dimensional cohomological localization and squashed q-deformations of two-dimensional Yang-Mills theory
Authors: Santilli, L.; Szabo, R. J.; Tierz, M.
Abstract: We revisit the duality between five-dimensional supersymmetric gauge theories and deformations of two-dimensional Yang-Mills theory from a new perspective. We give a unified treatment of supersymmetric gauge theories in three and five dimensions using cohomological localization techniques and the Atiyah-Singer index theorem. We survey various known results in a unified framework and provide simplified derivations of localiza- tion formulas, as well as various extensions including the case of irregular Seifert fibrations. We describe the reductions to four-dimensional gauge theories, and give an extensive de- scription of the dual two-dimensional Yang-Mills theory when the three-dimensional part of the geometry is a squashed three-sphere, including its extension to non-zero area, and a detailed analysis of the resulting matrix model. The squashing parameter b yields a fur- ther deformation of the usual q-deformation of two-dimensional Yang-Mills theory, which for rational values b2 = p/s yields a new correspondence with Chern-Simons theory on lens spaces L(p, s).Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10071/206092020-01-01T00:00:00ZDilatonic black holes in superstring gravity
http://hdl.handle.net/10071/17941
Title: Dilatonic black holes in superstring gravity
Authors: Moura, F.
Abstract: We solve the dilaton field equation in the background of a spherically symmetric black hole in type II superstring theory with ?'3 corrections in arbitrary d spacetime dimensions. We then apply this result to obtain a spherically symmetric black hole solution with ?'3 corrections, in superstring theory compactified on a torus, coupled to such dilaton. For this black hole we obtain its mass, entropy, temperature, specific heat, and free energy.Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10071/179412019-01-01T00:00:00ZOn uniqueness of stationary vacuum black holes
http://hdl.handle.net/10071/14975
Title: On uniqueness of stationary vacuum black holes
Authors: Chrusciel, P. T.; Costa, J. L.
Abstract: We prove uniqueness of the Kerr black holes within the connected, non-degenerate, analytic class of regular vacuum black holes.
Description: WOS:000272458700010 (Nº de Acesso Web of Science)Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10071/149752008-01-01T00:00:00Z