The top threshold effect in the $\gamma\gamma$ production at the LHC

TL;DR

This paper analyzes the top quark threshold effects on diphoton production at the LHC, showing a detectable feature in the invariant mass distribution near twice the top quark mass, with implications for future observations.

Contribution

It provides a detailed calculation of the top threshold contribution to diphoton production and introduces an empirical fit to identify this feature at the LHC.

Findings

Threshold effect appears near twice the top quark mass in the $M_{ ext{\gamma\gamma}}$ distribution.

The magnitude of the effect is quantified and shown to be potentially observable at the LHC.

Possible improvements are discussed to enhance the detection significance.

Abstract

We compute the top quark threshold contributions to the $\gamma\gamma$ production at the LHC. They appear when the invariant mass of the photon pair, $M_{\gamma\gamma}$ just exceeds two times the mass of the top quark and induce some feature in the $M_{\gamma\gamma}$ distribution. We determine the magnitude of this threshold effect and characterize this feature with a simple empirical fitting function to show that it is possible to observe this effect at the LHC in future. We also explore some possible improvements that may enhance its significance.