Hamiltonian description of singular Lagrangian systems with spontaneously broken time translation symmetry

TL;DR

This paper provides a Hamiltonian framework for singular Lagrangian systems that spontaneously break time translation symmetry, clarifying their structure and avoiding multivalued energy functions through phase space enlargement.

Contribution

It introduces a Hamiltonian description that resolves singularities and multivaluedness in models of spontaneous time translation symmetry breaking.

Findings

Multivalued energy functions can be avoided with phase space enlargement.

Spontaneous breaking of time translation also breaks time reversal.

Hamiltonian formalism clarifies the structure of symmetry-breaking ground states.

Abstract

Shapere and Wilczek recently found some singular Lagrangian systems which spontaneously breaks time translation symmetry. The common feature of their models is that the energy functions are multivalued in terms of the canonical phase space variables and the symmetry breaking ground states are all located at the brunching point singularities. By enlarging the phase space and making use of Dirac's theory on constrained Hamiltonian systems, we present the Hamiltonian description of some of the models discussed by Shapere and Wilczek and found that both the multivaluedness and the brunching point singularities can be avoided, while the spontaneous breaking oftime translation becomes more transparent. It is also shown that the breaking of time translation is always accompanied by the breaking of time reversal.