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Soft Photon and Graviton Theorems in Effective Field Theory
Henriette Elvang1, Callum R T Jones1, Stephen G Naculich2
1Michigan Center for Theoretical Physics and Randall Laboratory of Physics, Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
This study extends soft theorems for photons and gravitons in effective field theories. New terms are identified for photons and gravitons, with a classification of operators and consistency conditions derived.
Area of Science:
- Theoretical physics
- Quantum field theory
- String theory
Background:
- Soft theorems relate low-energy behavior of scattering amplitudes to symmetries.
- Previous work focused on leading order and specific particle types.
Purpose of the Study:
- Extend photon and graviton soft theorems to higher orders in effective field theories.
- Classify local operators modifying these theorems.
- Derive consistency conditions from a master formula.
Main Methods:
- Derivations in 4D local effective field theories with massless particles of arbitrary spin.
- Manifestly on-locus soft limit extraction using complex momentum deformation.
- Analysis of local operator contributions to soft theorems.
Main Results:
- New subleading terms for photon soft theorems and subsubleading terms for graviton soft theorems identified.
- Complete classification of local operators responsible for these modifications provided.
- Demonstrated that no local operators modify the subleading soft graviton theorem.
Conclusions:
- The master formula yields new soft theorems and crucial consistency conditions.
- Conditions include charge conservation, Einstein equivalence principle, and supergravity Ward identities.
- Established constraints on particle couplings based on spin.
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