Effective field theory of time-translational symmetry breaking in nonequilibrium open system

Masaru Hongo, Suro Kim, Toshifumi Noumi, Atsuhisa Ota

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We develop the effective field theoretical (EFT) approach to time-translational symmetry breaking of nonequilibrium open systems based on the Schwinger-Keldysh formalism. In the Schwinger-Keldysh formalism, all the symmetries of the microscopic Lagrangian are doubled essentially because the dynamical fields are doubled to describe the time-evolution along the closed-time-path. The effective Lagrangian for open systems are then obtained by coarse-graining the microscopic Schwinger-Keldysh Lagrangian. As a consequence of coarse-graining procedure, there appear the noise and dissipation effects, which explicitly break the doubled time-translational symmetries into a diagonal one. We therefore need to incorporate this symmetry structure to construct the EFT for Nambu-Goldstone bosons in symmetry broken phases of open systems. Based on this observation together with the consistency of the Schwinger-Keldysh action, we construct and study the general EFT for time-translational symmetry breaking in particular, having in mind applications to synchronization, time crystal, and cosmic inflation.
Original languageEnglish
JournalJournal of High Energy Physics
Publication statusPublished - 20 Feb 2019


  • Effective Field Theories
  • Quantum Dissipative Systems
  • Space-Time Symmetries
  • Spontaneous Symmetry Breaking


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