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abstract: 'We present a class of new black hole solutions in $D$-dimensional Lovelock gravity theory. The solutions have a form of direct product $\mathcal{M}^m \times \mathcal{H}^{n}$, where $D=m+n$, $\mathcal{H}^n$ is a negative constant curvature space, and the solutions are characterized by two integration constants. When $m=3$ and $4$, these solutions reduce to the exact black hole solutions recently found by Maeda and Dadhich in Gauss-Bonnet gravity theory. We study thermodynamics of these black hole solutions. Although these black holes have a nonvanishing Hawking temperature, surprisingly, the mass of these solutions always vanishes. While the entropy also vanishes when $m$ is odd, it is a constant determined by Euler characteristic of $(m-2)$-dimensional cross section of black hole horizon when $m$ is even. We argue that the constant in the entropy should be thrown away. Namely, when $m$ is even, the entropy of these black holes also should vanish. We discuss the implications of these results.'
address:
- '$^{a}$ Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190, China\'
- '$^{b}$ Department of Physics, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan'
author:
- 'Rong-Gen Cai$^{a,b,}$[^1], Li-Ming Cao$^{b,}$[^2], Nobuyoshi Ohta$^{b,}$[^3]'
title: Black 