Articles

Soft theorems for boosts and other time symmetries

Hui, Lam; Joyce, Austin; Komissarov, Ilia; Parmentier, Klaas; Santoni, Luca; Wong, Sam S. C.

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.

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Also Published In

Title
Journal of High Energy Physics
DOI
https://doi.org/10.1007/JHEP02(2023)123

More About This Work

Published Here
July 22, 2024

Notes

Classical Theories of Gravity, Effective Field Theories, Space-Time Symmetries, Spontaneous Symmetry Breaking