Large Interval Limit of R\'enyi Entropy At High Temperature

Understand

In this paper, we propose a novel expansion to compute the large interval limit of the R\'enyi entropy of 2D CFT at high temperature.

• Via the replica trick, the single interval R\'enyi entropy of 2D CFT at finite temperature could be read from the partition function on $n$-sheeted torus connected with each other along a branch cut.
• We calculate the partition function by inserting a complete basis across the branch cut.
• Because of the monodromy condition across the branch cut in the large interval limit, the basis of the states should be the ones in the twist sector.