
Symmetry in Nonlinear Mathematical Physics  2009
Nikolai Iorgov (Bogolyubov Institute for Theoretical Physics, Kyiv, Ukraine)
Formfactors of the finite quantum XYchain
Abstract:
Explicit factorized formulas for the matrix elements (formfactors) of the spin operators between the eigenvectors of the Hamiltonian of finite quantum XYchain in a transverse field were derived. The derivation is based on the relations between three models: the model of quantum XYchain, Ising model on 2D lattice and the N = 2 BaxterBazhanovStroganov (or τ^{(2)}) model. Due to these relations we transfer the formulas for the formfactors of the latter model
recently obtained by the use of separation of variables method to the model of quantum XYchain.
Hopefully, the formulas for the formfactors will help in analysis of multipoint multitime correlation functions at a finite temperature. As an example, we rederive the asymptotics of twopoint correlation function found by Barouch and McCoy without
the use of the Toeplitz determinants and the WienerHopf factorization method.

