Fatal Effects of Charges on Stability of Black Holes in Lovelock Theory

We study the stability of static spherically symmetric charged black holes under tensor type perturbations in Lovelock theory which is a natural higher dimensional generalization of Einstein theory. We derive the master equation for tensor type perturbations and present the criterions for the stability. Examining these criterions numerically, we show that a black hole with small charge has the instability if its mass is as small as extreme mass. Combined with our previous result that neutral black hole has no dynamical instability in odd dimensions, this result suggests that charges have fatal effects on black holes in Lovelock theory.Comment: 22 pages, 17 figures, using PTP format; v2: references adde

Instability of Small Lovelock Black Holes in Even-dimensions

We study the stability of static black holes in Lovelock theory which is a natural higher dimensional generalization of Einstein theory. We derive a master equation for tensor perturbations in general Lovelock theory. It turns out that the resultant equation is characterized by one functional which determines the background black hole solutions. Thus, the stability issue of static black holes under tensor perturbations in general dimensions is reduced to an algebraic problem. We show that small Lovelock black holes in even-dimensions are unstable.Comment: 14 pages, 2 figure

Pathologies in Lovelock AdS Black Branes and AdS/CFT

We study the pathologies in AdS black branes in Lovelock theory. More precisely, we examine the conditions that AdS black branes have the naked singularity, the ghost instability and the dynamical instability. From the point of view of the AdS/CFT correspondence, the pathologies in AdS black branes indicate the pathologies in the corresponding CFT. Hence, we need to be careful when we apply AdS/CFT in Lovelock theory to various phenomena such as the shear viscosity to entropy ratio in strongly coupled quantum filed theory.Comment: 11 pages, 5 figure

Catastrophic Instability of Small Lovelock Black Holes

We study the stability of static black holes in Lovelock theory which is a natural higher dimensional generalization of Einstein theory. We show that Lovelock black holes are stable under vector perturbations in all dimensions. However, we prove that small Lovelock black holes are unstable under tensor perturbations in even-dimensions and under scalar perturbations in odd-dimensions. Therefore, we can conclude that small Lovelock black holes are unstable in any dimensions. The instability is stronger on small scales and hence catastrophic in the sense that there is no smooth descendant.Comment: 23 pages, 3 figures; v2: references adde

Master Equations for Gravitational Perturbations of Static Lovelock Black Holes in Higher Dimensions

In this paper, we derive the master equations for gravitational perturbations of vector and scalar type for static vacuum Lovelock black holes. Together with our previous work on the tensor type perturbation, we now provide the full set of master equations that governs all types of gravitational perturbations of static vacuum Lovelock black holes in any dimensions.Comment: 16 pages; v2: references added; v3: typo

Chiral Primordial Gravitational Waves from a Lifshitz Point

We study primordial gravitational waves produced during inflation in quantum gravity at a Lifshitz point proposed by Ho${\rm\check{r}}$ava. Assuming power-counting renormalizability, foliation preserving diffeomorphism invariance, and the condition of detailed balance, we show that primordial gravitational waves are circularly polarized due to parity violation. The chirality of primordial gravitational waves is a quite robust prediction of quantum gravity at a Lifshitz point which can be tested through observations of cosmic microwave background radiation and stochastic gravitational waves.Comment: 4 pages,2 figures;v2:reference added; v3:reference adde