Constructing Massive Scattering Amplitudes for Electroweak Effective Field Theory



日時:2021年10月29日(金) 午前10時
講演者:北原 鉄平氏(名古屋大)
タイトル:Constructing Massive Scattering Amplitudes for Electroweak Effective Field Theory

アブストラクト: Usual calculation for quantum field theory relies on Lagrangian under a certain symmetry. Then, one can obtain amplitudes by taking Feynman rules and diagrams. In contrast, a method called ''scattering amplitudes'' (also called on-shell 
amplitudes, modern amplitude method, or spinor-helicity formalism) directly provides the amplitudes from symmetries without relying on Lagrangian. For example, calculations of gluon n-point scattering amplitudes can be greatly reduced in 
this method. This approach is expected to extract some essences in quantum field theory, which are not obvious in the usual Feynman methods. Basically, conventional scattering amplitudes are methods for the massless theory. From 2017, 
this method has been generalized to involve any-spin massive particles by Nima Arkani-Hamed group. In this talk, first, I will provide a brief review of the massless and massive scattering amplitudes. Next, I will introduce the scattering amplitude 
calculations connected with electroweak symmetry breaking, which are related to masses, vev, and longitudinal waves. In particular, we do not use the standard model Lagrangian. We derived (strictly speaking, we re-derived) several equations 
for electroweak symmetry breaking that are supposed to be inherent in field theory. Also, in such a bottom-up approach, we present the systematic derivation of independent three-point and four-point contact terms. This talk is based on arXiv:1909.10551 and arXiv:2008.09652.