title: Exact valence bond entanglement entropy and probability distribution in the XXX spin chain and the potts model.
abstract: We determine exactly the probability distribution of the number N_(c) of valence bonds connecting a subsystem of length L>>1 to the rest of the system in the ground state of the XXX antiferromagnetic spin chain. This provides, in particular, the asymptotic behavior of the valence-bond entanglement entropy S_(VB)=N_(c)ln2=4ln2/pi(2)lnL disproving a recent conjecture that this should be related with the von Neumann entropy, and thus equal to 1/3lnL. Our results generalize to the Q-state Potts model.
authors: LPTMS, Université Paris-Sud, Bâtiment 100, 91405 Orsay, France.
authors: J L
authors: JL
authors: Jacobsen
authors: H
authors: H
authors: Saleur