Soft theorems for boosts and other time symmetries
Lam Hui
(Center for Theoretical Physics, Department of Physics, Columbia University)
Austin Joyce
(Kavli Institute for Cosmological Physics, Department of Astronomy and Astrophysics, University of Chicago)
Ilia Komissarov
(Center for Theoretical Physics, Department of Physics, Columbia University)
Klaas Parmentier
(Center for Theoretical Physics, Department of Physics, Columbia University)
Luca Santoni
(ICTP, International Centre for Theoretical Physics)
Sam S. C. Wong
(Center for Particle Cosmology, Department of Physics and Astronomy, University of Pennsylvania)
Journal: Journal of High Energy Physics
•
• SpringerOpen
• ISSN: 1029-8479
Abstract
Abstract We derive soft theorems for theories in which time symmetries — symmetries that involve the transformation of time, an example of which are Lorentz boosts — are spontaneously broken. The soft theorems involve unequal-time correlation functions with the insertion of a soft Goldstone in the far past. Explicit checks are provided for several examples, including the effective theory of a relativistic superfluid and the effective field theory of inflation. We discuss how in certain cases these unequal-time identities capture information at the level of observables that cannot be seen purely in terms of equal-time correlators of the field alone. We also discuss when it is possible to phrase these soft theorems as identities involving equal-time correlators.
Lam Hui, Austin Joyce, Ilia Komissarov, et al. (2023). "Soft theorems for boosts and other time symmetries". Journal of High Energy Physics. https://doi.org/10.1007/jhep02(2023)123