Eur. Phys. J. C (2017) 77: 323
https://doi.org/10.1140/epjc/s10052-017-4884-8

Letter

Top-quark mass from the diphoton mass spectrum

¹ Institute of Convergence Fundamental Studies, Seoul National University of Science and Technology, Seoul, 01811, Korea
² Quantum Universe Center, KIAS, Seoul, 02455, Korea

^* e-mail: hyokoya@kias.re.kr

Received: 9 March 2017
Accepted: 5 May 2017
Published online: 18 May 2017

Abstract

We calculate the amplitude by including the 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.