Hard photons in hadroproduction of top quarks with realistic final states

Journal of High Energy Physics, Oct 2018

Abstract We present a complete description of top quark pair production in association with a hard photon in the dilepton channel. Our calculation is accurate to NLO in QCD. It is based on matrix elements for \( {e}^{+}{\nu}_e{\mu}^{-}{\overline{\nu}}_{\mu }b\overline{b}\upgamma \) production and includes all resonant and non-resonant diagrams, interferences, and off-shell effects of the top quarks and the W gauge bosons. This calculation constitutes the first full computation for top quark pair production with a final state photon in hadronic collisions at NLO in QCD. Numerical results for total and differential cross sections are presented for the LHC at a centre-of-mass energy of \( \sqrt{s}=13 \) TeV. For a few observables relevant for new physics searches, beyond some kinematic bounds, we observe shape distortions of more than 100%. In addition, we confirm that the size of the top quark off-shell effects for the total cross section is consistent with the expected uncertainties of the narrow width approximation. Results presented here are not only relevant for beyond the Standard Model physics searches but also important for precise measurements of the top-quark fiducial cross sections and top-quark properties at the LHC.

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Hard photons in hadroproduction of top quarks with realistic final states

Journal of High Energy Physics October 2018, 2018:158 | Cite as Hard photons in hadroproduction of top quarks with realistic final states AuthorsAuthors and affiliations G. BevilacquaH. B. HartantoM. KrausT. WeberM. Worek Open Access Regular Article - Theoretical Physics First Online: 25 October 2018 Abstract We present a complete description of top quark pair production in association with a hard photon in the dilepton channel. Our calculation is accurate to NLO in QCD. It is based on matrix elements for \( {e}^{+}{\nu}_e{\mu}^{-}{\overline{\nu}}_{\mu }b\overline{b}\upgamma \) production and includes all resonant and non-resonant diagrams, interferences, and off-shell effects of the top quarks and the W gauge bosons. This calculation constitutes the first full computation for top quark pair production with a final state photon in hadronic collisions at NLO in QCD. Numerical results for total and differential cross sections are presented for the LHC at a centre-of-mass energy of \( \sqrt{s}=13 \) TeV. For a few observables relevant for new physics searches, beyond some kinematic bounds, we observe shape distortions of more than 100%. In addition, we confirm that the size of the top quark off-shell effects for the total cross section is consistent with the expected uncertainties of the narrow width approximation. Results presented here are not only relevant for beyond the Standard Model physics searches but also important for precise measurements of the top-quark fiducial cross sections and top-quark properties at the LHC. Keywords NLO Computations QCD Phenomenology  ArXiv ePrint: 1803.09916 Download to read the full article text Notes Open Access This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited. References [1] M. Fael and T. Gehrmann, Probing top quark electromagnetic dipole moments in single-top-plus-photon production, Phys. Rev. D 88 (2013) 033003 [arXiv:1307.1349] [INSPIRE].ADSGoogle Scholar [2] J.A. Aguilar-Saavedra, E. Álvarez, A. Juste and F. Rubbo, Shedding light on the \( t\overline{t} \) asymmetry: the photon handle, JHEP 04 (2014) 188 [arXiv:1402.3598] [INSPIRE].ADSCrossRefGoogle Scholar [3] M. Schulze and Y. Soreq, Pinning down electroweak dipole operators of the top quark, Eur. Phys. J. C 76 (2016) 466 [arXiv:1603.08911] [INSPIRE].ADSCrossRefGoogle Scholar [4] S.M. Etesami, S. Khatibi and M. 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G. Bevilacqua, H. B. Hartanto, M. Kraus, T. Weber, M. Worek. Hard photons in hadroproduction of top quarks with realistic final states, Journal of High Energy Physics, 2018, 158, DOI: 10.1007/JHEP10(2018)158