Inclusive and differential $t\bar{t}\gamma$ measurement in the dilepton channel and effective field theory interpretation

TL;DR

This paper measures the $t\bar{t}\gamma$ production cross section in the dilepton channel using CMS data, providing both inclusive and differential results, and interprets the findings within an effective field theory framework to constrain top-photon coupling modifications.

Contribution

It presents the first combined measurement of $t\bar{t}\gamma$ in the dilepton channel with EFT interpretation and constraints on Wilson coefficients, using a large dataset from the CMS experiment.

Findings

Measured $t\bar{t}\gamma$ cross section with high precision.

Set new limits on EFT Wilson coefficients $c_{tZ}$ and $c_{tZ}^{\mathrm{I}}$.

Combined results improve sensitivity to top-photon interactions.

Abstract

The production cross section of $t\bar{t}\gamma$ is measured in the dilepton channel using 138 fb$^{-1}$ of proton-proton collision data recorded by the CMS experiment at $\sqrt{s}= 13 $ TeV during the 2016-2018 data-taking period of the CERN LHC. A fiducial phase space is defined at the particle level in which both inclusive and differential results are provided. The $t\bar{t}\gamma$ process is sensitive to EFT operators that modify the top-photon coupling, so that tight constraints on the $c_{tZ}$ and $c_{tZ}^{\mathrm{I}}$ Wilson coefficients can be extracted. Finally, the EFT interpretation is repeated on a combination of this result and a measurement of $t\bar{t}\gamma$ production in the lepton+jets channel.