A formula for scalar products of Bethe wave functions in the nonlinear Schrödinger model of spin- (1)/(2) particles is proposed. It is shown, in addition, that one can replace conjugate states by dual eigenfunctions to calculate correlation functions for integrable systems.
Abstract We calculate the scalar product of Bethe states of the XXZ spin- 1 2 chain with general integrable boundary conditions. The off-shell equations satisfied by the transfer matrix and the off-shell Bethe vectors allow one to derive a linear system for the scalar product of off-shell and on-shell Bethe states. We show that this linear system can be solved in terms of a compact determinant formula that involves the Jacobian of the transfer matrix eigenvalue and certain q -Pochhammer polynomials of the boundary couplings.
In this note we adress the problem of performing the semiclassical expansion of the scalar product of Bethe states in the case of the XXZ spin chain. Our approach closely follows the one developped in [1]: after expressing the scalar products in terms of a central quantity - the B functional, we reinterpret it as a grand partition function of a gas of particles with pairwise interaction potential. This work has been done as part of the author's master thesis under the supervision of Ivan Kostov and Didina Serban at Institut de Physique Théorique (CEA Saclay) in September 2015 - February 2016, and present a consice summary of the results obtained at that time.