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[[UTAPwiki/セミナー/初期宇宙・相対論速報]] Speaker 1: Nami Uchikata Title : "New solutions of charged regular black holes and their stability" Abstract : Regular black holes are black holes without spacetime singularities. We construct one of regular black hole models, which is composed of de Sitter and Reissner-Nordstrom spacetimes separated by a thin shell. We have assumed the shell is dust and timelike. We have numerically obtained new solutions of such a regular black hole model and also examined the stability against the radial displacement of the shell. The black hole parameters of the stable solutions obtained in this study range in 0.87L < m < 2L and Q/m > 0.86, where m, L, and Q are the mass of the black hole, de Sitter horizon radius and charge of the black hole, respectively. Speaker 2: Chunshan Lin TBA Title: "Cosmological Perturbations in Extended Massive Gravity" Abstract: During this talk, I will talk about the cosmological perturbation analysis on the quasi-dialton theory and varying mass massive gravity theory. We will show that the ghost is a robust feature in the quasi-dilaton theory. On the other hand, the varying mass theory can be ghost free in some proper parameter region. |