Top-quark mass from the diphoton mass spectrum

Abstract

Abstract We calculate the $$gg\rightarrow \gamma \gamma $$ g g → γ γ amplitude by including the $$t\bar{t}$$ t t ¯ bound-state effects near their mass threshold. In terms of the non-relativistic expansion of the amplitude, the LO contribution is an energy-independent term in the one-loop amplitude. We include the NLO contribution described by the non-relativistic Green function and part of the NNLO contribution. Despite a missing NLO piece which can be accomplished with the two-loop-level amplitude via massive quarks, the shape of the diphoton mass spectrum is predicted with a good accuracy. Thanks to the simple and clean nature of the observable, its experimental measurement can be a direct method to determine the short-distance mass of the top quark at hadron colliders.

Keywords

• Green Function
• Hadron Collider
• NNLO Correction
• Gluon Distribution Function
• Future Circular Collider