Expanding Universe and Dynamical Compactification Using Yang-Mills Instantons

We consider an eight-dimensional Einstein-Yang-Mills theory to explore whether Yang-Mills instantons formed in extra dimensions can induce the dynamical instability of our four-dimensional spacetime. We show that the Yang-Mills instantons in extra dimensions can trigger the expansion of our universe in four-dimensional spacetime as well as the dynamical compactification of extra dimensions. We also discuss a possibility to realize a reheating mechanism via the quantum back-reaction from the contracting tiny internal space with a smeared instanton.Comment: v3; 26 pages, 6 figures, version to be published in JHE

Configuration entropy and instability of accelerating black hole in AdS

We consider the accelerating black hole with the negative cosmological constant in four-dimensional spacetime. There are two configurations such as the black string (BS) phase when the mass parameter is zero and the black hole (BH) phase when the mass parameter is non-zero. We investigate their stability via the configuration entropy (CE). It is found that the BS is not always stable but the BH has a thermally stable range below the critical mass of the BH, which is consistent with thermodynamic instability.Comment: 7 pages, 7 figure