On the Riemann–Hilbert approach to asymptotic analysis of the correlation functions of the quantum nonlinear Schrödinger equation: Interacting fermion case

We consider the local field dynamic temperature correlation function of the quantum nonlinear Schrödinger equation with a finite coupling constant. This correlation function admits a Fredholm determinant representation. The related operator-valued Riemann–Hilbert problem is used to analyze the leading term of the large time and distance asymptotic expansion of the correlation function.