title: Universal Features of Left-Right Entanglement Entropy.
abstract: We show the presence of universal features in the entanglement entropy of regularized boundary states for (1+1)D conformal field theories on a circle when the reduced density matrix is obtained by tracing over right- or left-moving modes. We derive a general formula for the left-right entanglement entropy in terms of the central charge and the modular S matrix of the theory. When the state is chosen to be an Ishibashi state, this measure of entanglement is shown to precisely reproduce the spatial entanglement entropy of a (2+1)D topological quantum field theory. We explicitly evaluate the left-right entanglement entropies for the Ising model, the tricritical Ising model and the su[over ^](2)_{k} Wess-Zumino-Witten model as examples.
authors.affiliation: Department of Physics, University of California at San Diego, La Jolla, California 92093, USA.
authors.forename: Diptarka
authors.initials: D
authors.lastname: Das
authors.affiliation: Centre for High Energy Physics, Indian Institute of Science, C. V. Raman Avenue, Bangalore 560012, India.
authors.forename: Shouvik
authors.initials: S
authors.lastname: Datta