Entanglement of local operators in large-N conformal field theories

In this paper, we study Renyi and von Neumann entanglement entropy of excited states created by local operators in large-N (or large-central-charge) conformal field theories (CFTs). First we point out that a naive large-N expansion can break down for the von Neumann entanglement entropy, while it does not for the Renyi entanglement entropy. This happens even for the excited states in free Yang-Mills theories. Next, we analyze strongly coupled large-N CFTs from both the field-theoretic and holographic viewpoints. We find that the Renyi entanglement entropy of the excited state, produced by a local operator, grows logarithmically under its time evolution and its coefficient is proportional to the conformal dimension of the local operator.