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

Understand

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.