Supersymmetric field theory of a nonequilibrium stochastic system as applied to disordered heteropolymers

A supersymmetric field-theoretical scheme is derived based on the Langevin equation, which enables memory and nonergodicity effects in a nonequilibrium stochastic system with quenched disorder to be described in an optimal manner. This scheme is applied to a disordered heteropolymer whose effective Hamiltonian is found to be simply the free energy as a function of the compositional order parameter. Instead of the Langevin equation, an effective equation of motion is used here to describe the way different monomers alternate as we move along a polymer chain. The isothermal and adiabatic susceptibilities, memory parameter, and irreversible response are determined as functions of the temperature and the intensity of quenched disorder.