# Top-quark mass from the diphoton mass spectrum

The European Physical Journal C, May 2017

We calculate the $gg\rightarrow \gamma \gamma$ amplitude by including the $t\bar{t}$ 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.

This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1140%2Fepjc%2Fs10052-017-4884-8.pdf

Sayaka Kawabata, Hiroshi Yokoya. Top-quark mass from the diphoton mass spectrum, The European Physical Journal C, 2017, 323, DOI: 10.1140/epjc/s10052-017-4884-8