Branched Hamiltonians and time translation symmetry breaking in equations of the Lienard type

Abstract

Shapere and Wilczek ( Phys. Rev. Lett. 109, 160402 and 200402 (2012)) have recently described certain singular Lagrangian systems which display spontaneous breaking of time translation symmetry. We begin by considering the standard Lienard equation for which a Lagrangian is constructed by using the method of Jacobi Last Multiplier. The velocity dependance of the Lagrangian is such that the momentum may exhibit multivaluedness thereby leading to the so called branched Hamiltonian. Next with a quadratic velocity dependance in the Lienard equation one can construct a Hamiltonian description involving a position dependent mass. We compute the Lagrangian and Hamiltonian of this system and show that the canonical Hamiltonian is single valued . However, we find that up to a constant shift, the square of this Hamiltonian describes systems giving rise to spontaneous time translation symmetry breaking provided the potential function is negative