Effective Field Theories from Soft Limits of Scattering Amplitudes
2015; American Physical Society; Volume: 114; Issue: 22 Linguagem: Inglês
10.1103/physrevlett.114.221602
ISSN1092-0145
AutoresClifford Cheung, Karol Kampf, Jiří Novotný, Jaroslav Trnka,
Tópico(s)Particle physics theoretical and experimental studies
ResumoWe derive scalar effective field theories - Lagrangians, symmetries, and all - from on-shell scattering amplitudes constructed purely from Lorentz invariance, factorization, a fixed power counting order in derivatives, and a fixed order at which amplitudes vanish in the soft limit. These constraints leave free parameters in the amplitude which are the coupling constants of well-known theories: Nambu-Goldstone bosons, Dirac-Born-Infeld scalars, and Galileons. Moreover, soft limits imply conditions on the Noether current which can then be inverted to derive Lagrangians for each theory. We propose a natural classification of all scalar effective field theories according to two numbers which encode the derivative power counting and soft behavior of the corresponding amplitudes. In those cases where there is no consistent amplitude, the corresponding theory does not exist.
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