Probing the nonstandard top-gluon couplings through $t\bar{t}\gamma\gamma$ production at the LHC

TL;DR

This paper explores how top quark anomalous dipole moments can be constrained by analyzing $t\bar{t}\gamma\gamma$ production at the LHC, introducing a new cross section ratio to improve sensitivity.

Contribution

It proposes a novel method using the $R_{2\gamma/\gamma}$ ratio and $H_T$ variable to better constrain nonstandard top-gluon couplings at the LHC.

Findings

The $R_{2\gamma/\gamma}$ ratio effectively cancels systematic uncertainties.

Limits on top quark dipole moments are improved with the new method.

The approach enhances sensitivity to anomalous couplings with expected LHC data.

Abstract

In this paper, we investigate the anomalous chromoelectric and chromomagnetic dipole moments of the top quark through top pair production in association with two photons at the LHC. We first present the strategy to reconstruct this process assuming a different source for background processes. Then, we focus on the existing constraints from inclusive top-pair production from the Tevatron and LHC, adding the new LHC measurement. Afterwards, we introduce the new cross section ratio $R_{2\gamma/\gamma}=\sigma_{t\bar{t}\gamma\gamma}/\sigma_{t\bar{t}\gamma}$ and show the usefulness of this ratio in canceling most of the systematic uncertainties and its special functionality to constrain dipole moments. Finally, we use the scalar sum of the transverse momentum of jets, $H_{T}$, in order to define a signal-dominated region and obtain limits on these anomalous top couplings using different amounts of expected data from the LHC.