标题： 黑洞的十字路口：二次引力中的晚期蒸发 显示英文标题

标题： Black holes at a crossroads: late-stage evaporation in quadratic gravity

摘要： 在广义相对论中，黑洞蒸发会导致突然的能量爆发和信息丢失。 可以认为这些现象发生在蒸发的最后阶段，在该阶段，经典半经典的近似需要通过量子修正来改进，甚至对于引力相互作用也是如此。 描述高能引力的一种自然方式是在爱因斯坦-希尔伯特作用量中加入二次曲率项，即二次引力。 在宇宙学层面上，众所周知，它的经典解可以产生一个与观测结果非常吻合的暴涨模型；而在天体物理环境中，它允许小质量下存在非史瓦西黑洞的可能性。 这些解具有非常特殊的性质，这是由于存在一个在量子水平上表现为幽灵的有质量自旋-2粒子。 非史瓦西解的分支在特定的质量处与史瓦西解的分支相交，这个质量可能介于小行星质量和普朗克质量之间，具体取决于略微受限的自由参数的取值。 通过对它们的动力学稳定性和热力学性质进行分析，我们研究了当黑洞蒸发到这一交叉点时可能发生的情况。 虽然这项研究可能无法解决蒸发终点的问题，但它可以揭示蒸发末期可能出现的方向。 显示英文摘要

摘要： In General Relativity black hole evaporation leads to sudden bursts of energy and loss of information. It can be argued that these phenomena happen in the final stages of evaporation, where the semiclassical approximation needs to be refined with quantum corrections also for the gravitational interaction. A natural way to describe gravity at high energies is to add quadratic curvature terms to the Einstein-Hilbert action, i.e. quadratic gravity. At the cosmological level it is known that its classical solutions can give rise to a model of inflation that matches observations strikingly well, while in an astrophysical context it allows for the possibility of non-Schwarzschild black holes at small masses. These solutions have very peculiar properties, due to the presence of a massive spin-2 particle corresponding to a ghost at the quantum level. The branch of non-Schwarzschild solutions crosses the one of Schwarzschild ones at a specific mass which could be between the one of an asteroid and the Planck mass, depending on the value of a slightly constrained free parameter. By analyzing their dynamical stability and thermodynamical properties, we investigate what could happen to a black hole that has evaporated to this crossing point. While this investigation might not solve the problem of the endpoint of evaporation, it can shed light on the directions it might take during its last moments.