On AdS to dS transitions in higher-curvature gravity

Abstract

Abstract:We study the possible existence of gravitational phase transitions from AdS to dS geometries in the context of higher-curvature gravities. We use Lanczos-Gauss-Bonnet (LGB) theory with a positive cosmological constant as a toy model. This theory has two maximally symmetric vacua with positive (dS) and negative (AdS) constant curvature. We show that a phase transition from the AdS vacuum to a dS black hole geometry takes place when the temperature reaches a critical value. The transition is produced by nucleation of bubbles of the new phase that expand afterwards. We claim that this phenomenon is not particular to the model under study, that contains Boulware-Deser instabilities, but shall also be part of generic gravitational theories with higher-curvature terms, where these problems are absent. A salient feature that emerges when a positive cosmological constant is considered is that the temperature in which these bubbles may form is bounded from above. Thermodynamically this property is related to quite an uncommon feature that this system exhibits, namely, the existence of a zeroth-order phase transition.

Thermalon mediated phase transitions in Gauss-Bonnet gravity

“…In addition to showing the results previously studied in [6,7,31] are consistent with the extended phase space paradigm, we have found a number of new and interesting features of these transitions. In terms of the effect of the thermodynamic pressure, we have shown that for any given value of the Gauss-Bonnet coupling, for large enough negative pressures (i.e.…”

“…We build upon the approach of [7] by performing an exhaustive analysis of the pressure parameter space.…”

“…lower in free energy) above a certain critical temperature. A number of recent studies have focused on thermalon mediated phase transitions in higher curvature gravity [6,7,9]. These phase transitions proceed via the nucleation of spherical shells, called thermalons, that separate spacetime into two regions described by different branches of the solution, hosting a black hole in the interior.…”

Gravitational phase transition mediated by thermalon in Einstein-Gauss-Bonnet-Maxwell-Kalb-Ramond gravity

“…Thermalon, the Euclidean sector of the thermally activated bubble nucleation [16][17][18], is one of compelling mechanisms for mediating gravitational phase transition. More interestingly in higher-order theories of gravity, a number of recent studies have focused on JHEP08(2020)100 thermalon mediated phase transitions [19][20][21][22][23] in many cases of Lovelock gravity with a vacuum solution. These types of phase transitions proceed through the nucleation of the spherical thin-shell bubbles, so-called thermalon.…”

“…Once the cosmological constant is fixed, it was shown in refs. [19,20,22] that thermal AdS space underwent a thermalon-mediated phase transition to an asymptotically dS black hole geometry. This is a so-called the generalize HP (gravitational) phase transition which is different from original HP phase transition for the fact that the thermal AdS vacuum decays into a black hole belonging to a different (dS) branch solution.…”