Riemann surface crossover for the spectral gaps of open TASEP

Abstract: We consider the totally asymmetric simple exclusion process with open boundaries, at the edge of the maximal current phase. Using analytic continuations from the known stationary eigenvalue, we obtain exact expressions for the spectral gaps in the limit of large system size. The underlying Riemann surface,generated by modified Lambert functions, interpolates between the one for periodic TASEP and the one for open TASEP in the maximal current phase.