Roy equation analyses of $ππ$ scatterings at unphysical pion masses

Abstract

We use an extended Roy equation including a bound state pole to study ππ scatterings at unphysical large pion masses when σ becomes a bound state. The coupled integral equations at large pion masses are solved by taking the lattice driving terms and the Regge amplitudes as inputs. Relying on the solutions of Roy equations that respect unitarity, analyticity and crossing symmetry, we give predictions to the phase shifts with IJ = 00, 11, 20 in the elastic energy region. We then perform analytical continuation into complex plane to search various poles, all of which are inside the validity domain of Roy equation.