New Soft Theorems for Goldstone-Boson Amplitudes

Karol Kampf, Jiri Novotny, Mikhail Shifman, Jaroslav Trnka

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In this Letter we discuss new soft theorems for the Goldstone-boson amplitudes with nonvanishing soft limits. The standard argument is that the nonlinearly realized shift symmetry leads to the vanishing of scattering amplitudes in the soft limit, known as the Adler zero. This statement involves certain assumptions of the absence of cubic vertices and the absence of linear terms in the transformations of fields. For theories which fail to satisfy these conditions, we derive a new soft theorem which involves certain linear combinations of lower point amplitudes, generalizing the Adler zero statement. We provide an explicit example of the SU(N)/SU(N-1) sigma model which was also recently studied in the context of U(1) fibrated models. The soft theorem can be then used as an input into the modified soft recursion relations for the reconstruction of all tree-level amplitudes.

Original languageEnglish (US)
Article number111601
JournalPhysical review letters
Issue number11
StatePublished - Mar 20 2020

Bibliographical note

Funding Information:
This work is supported in part by the Czech Government projects GACR 18-17224S and LTAUSA17069, by U.S. DOE Grants No. DE-SC0009999 and No. DE-SC0011842, and the funds of University of California.

Publisher Copyright:
© 2020 authors. Published by the American Physical Society.


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