On one-loop entanglement entropy of two short intervals from OPE of twist operators

We investigate the one-loop entanglement entropy of two short intervals with small cross ratio x on a complex plane in two-dimensional conformal field theory (CFT) using operator product expansion of twist operators. We focus on the one-loop entanglement entropy instead of the general order n Rényi entropy, and this makes the calculation much easier. We consider the contributions of stress tensor to order x¹⁰, contributions of W₃ operator to order x¹², and contributions of W₄ operator to order x¹⁴. The CFT results agree with the ones in gravity.