NLO QCD predictions for $\boldsymbol{t\bar{t}γ}$ with realistic photon isolation

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Main Authors: Stremmer, Daniel, Worek, Malgorzata
Format: Preprint
Published: 2024
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author Stremmer, Daniel
Worek, Malgorzata
author_facet Stremmer, Daniel
Worek, Malgorzata
contents We present a complete description of top quark pair production in association with a hard photon in the di-lepton decay channel. The calculation is performed at NLO QCD and includes all resonant and non-resonant Feynman diagrams, interferences, and finite-width effects of the top quarks and $W^\pm/Z$ gauge bosons. We provide the results for the $pp\to e^+ν_e \,μ^- \barν\, b\bar{b}\,γ+X$ process using the fixed-cone, smooth-cone and hybrid-photon isolation criteria. The fixed-cone isolation criterion allows contributions from collinear photon radiation off QCD partons, which requires the inclusion of parton-to-photon fragmention processes. To this end, we include the latter contributions into our computational framework. We quantify the impact of different photon-isolation prescriptions on the integrated and differential cross-section predictions for the LHC at a centre-of-mass energy of $\sqrt{s}=13.6$ TeV. Our state-of-the-art NLO QCD results with the fixed-cone criterion allow us to reproduce the photon-isolation prescription employed in ATLAS and CMS. This will help to improve future comparisons with the LHC data.
format Preprint
id arxiv_https___arxiv_org_abs_2411_02196
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle NLO QCD predictions for $\boldsymbol{t\bar{t}γ}$ with realistic photon isolation
Stremmer, Daniel
Worek, Malgorzata
High Energy Physics - Phenomenology
High Energy Physics - Experiment
We present a complete description of top quark pair production in association with a hard photon in the di-lepton decay channel. The calculation is performed at NLO QCD and includes all resonant and non-resonant Feynman diagrams, interferences, and finite-width effects of the top quarks and $W^\pm/Z$ gauge bosons. We provide the results for the $pp\to e^+ν_e \,μ^- \barν\, b\bar{b}\,γ+X$ process using the fixed-cone, smooth-cone and hybrid-photon isolation criteria. The fixed-cone isolation criterion allows contributions from collinear photon radiation off QCD partons, which requires the inclusion of parton-to-photon fragmention processes. To this end, we include the latter contributions into our computational framework. We quantify the impact of different photon-isolation prescriptions on the integrated and differential cross-section predictions for the LHC at a centre-of-mass energy of $\sqrt{s}=13.6$ TeV. Our state-of-the-art NLO QCD results with the fixed-cone criterion allow us to reproduce the photon-isolation prescription employed in ATLAS and CMS. This will help to improve future comparisons with the LHC data.
title NLO QCD predictions for $\boldsymbol{t\bar{t}γ}$ with realistic photon isolation
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2411.02196