Author:
Inami Takeo,Kubota Takahiro
Abstract
Abstract
The flavor-changing gravitational process, d → s + graviton, is evaluated at the one-loop level in the standard electroweak theory with on-shell renormalization. The results that we present in the ’t Hooft–Feynman gauge are valid for on- and off-shell quarks and for all external and internal quark masses. We show that there exist non-decoupling effects of the internal heavy top quark in interactions with gravity. A naive argument taking account of the quark Yukawa coupling suggests that the amplitude of the process d → s + graviton in the large top quark mass limit would possibly acquire an enhancement factor $m_{t}^{2}/M_{W}^{2}$, where mt and MW are the top quark and the W-boson masses, respectively. In practice this leading enhancement is absent in the renormalized amplitude due to cancellation. Thus the non-decoupling of the internal top quark takes place at the ${\cal O}(1)$ level. The flavor-changing two- and three-point functions are shown to satisfy the Ward–Takahashi identity, which is used as a consistency check for the aforementioned cancellation of the ${\cal O}(m_{t}^{2}/M_{W}^{2})$ terms. Among the ${\cal O}(1)$ non-decoupling terms, we sort out those that can be regarded as due to the effective Lagrangian in which quark bilinear forms are coupled to the scalar curvature.
Publisher
Oxford University Press (OUP)
Subject
General Physics and Astronomy