#### 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
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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. Mohammadi Najafabadi, Measuring anomalous WW γ and t \( \overline{t}\gamma \) couplings using top+ γ production at the LHC, Eur. Phys. J. C 76 (2016) 533 [arXiv:1606.02178] [INSPIRE].ADSCrossRefGoogle Scholar
[5]
U. Baur, M. Buice and L.H. Orr, Direct measurement of the top quark charge at hadron colliders, Phys. Rev. D 64 (2001) 094019 [hep-ph/0106341] [INSPIRE].
[6]
U. Baur, A. Juste, L.H. Orr and D. Rainwater, Probing electroweak top quark couplings at hadron colliders, Phys. Rev. D 71 (2005) 054013 [hep-ph/0412021] [INSPIRE].
[7]
CDF collaboration, T. Aaltonen et al., Evidence for \( t\overline{t}\upgamma \) Production and Measurement of \( {\sigma}_{t\overline{t}\upgamma}/{\sigma}_{t\overline{t}} \), Phys. Rev. D 84 (2011) 031104 [arXiv:1106.3970] [INSPIRE].
[8]
ATLAS collaboration, Observation of top-quark pair production in association with a photon and measurement of the \( t\overline{t}\upgamma \) production cross section in pp collisions at \( \sqrt{s}=7 \) TeV using the ATLAS detector, Phys. Rev. D 91 (2015) 072007 [arXiv:1502.00586] [INSPIRE].
[9]
ATLAS collaboration, Measurement of the \( t\overline{t}\upgamma \) production cross section in proton-proton collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, JHEP 11 (2017) 086 [arXiv:1706.03046] [INSPIRE].
[10]
CMS collaboration, Measurement of the semileptonic \( t\overline{t}\upgamma \) production cross section in pp collisions at \( \sqrt{s}=8 \) TeV, JHEP 10 (2017) 006 [arXiv:1706.08128] [INSPIRE].
[11]
P.-F. Duan, W.-G. Ma, R.-Y. Zhang, L. Han, L. Guo and S.-M. Wang, QCD corrections to associated production of \( t\overline{t}\upgamma \) at hadron colliders, Phys. Rev. D 80 (2009) 014022 [arXiv:0907.1324] [INSPIRE].ADSGoogle Scholar
[12]
P.-F. Duan, R.-Y. Zhang, W.-G. Ma, L. Han, L. Guo and S.-M. Wang, Next-to-leading order QCD corrections to \( t\overline{t}\upgamma \) production at the 7 TeV LHC, Chin. Phys. Lett. 28 (2011) 111401 [arXiv:1110.2315] [INSPIRE].ADSCrossRefGoogle Scholar
[13]
F. Maltoni, D. Pagani and I. Tsinikos, Associated production of a top-quark pair with vector bosons at NLO in QCD: impact on \( \mathrm{t}\overline{\mathrm{t}}\mathrm{H} \) searches at the LHC, JHEP 02 (2016) 113 [arXiv:1507.05640] [INSPIRE].ADSCrossRefGoogle Scholar
[14]
P.-F. Duan, Y. Zhang, Y. Wang, M. Song and G. Li, Electroweak corrections to top quark pair production in association with a hard photon at hadron colliders, Phys. Lett. B 766 (2017) 102 [arXiv:1612.00248] [INSPIRE].ADSCrossRefGoogle Scholar
[15]
P. Nason, A New method for combining NLO QCD with shower Monte Carlo algorithms, JHEP 11 (2004) 040 [hep-ph/0409146] [INSPIRE].
[16]
S. Frixione, P. Nason and C. Oleari, Matching NLO QCD computations with Parton Shower simulations: the POWHEG method, JHEP 11 (2007) 070 [arXiv:0709.2092] [INSPIRE].ADSCrossRefGoogle Scholar
[17]
A. Kardos and Z. Trócsányi, Hadroproduction of \( t\hbox{-} \overline{t} \) pair in association with an isolated photon at NLO accuracy matched with parton shower, JHEP 05 (2015) 090 [arXiv:1406.2324] [INSPIRE].ADSCrossRefGoogle Scholar
[18]
K. Melnikov, M. Schulze and A. Scharf, QCD corrections to top quark pair production in association with a photon at hadron colliders, Phys. Rev. D 83 (2011) 074013 [arXiv:1102.1967] [INSPIRE].ADSGoogle Scholar
[19]
Z. Bern, L.J. Dixon, F. Febres Cordero, S. Höche, H. Ita, D.A. Kosower et al., Ntuples for NLO Events at Hadron Colliders, Comput. Phys. Commun. 185 (2014) 1443 [arXiv:1310.7439] [INSPIRE].ADSCrossRefGoogle Scholar
[20]
J. Alwall et al., A Standard format for Les Houches event files, Comput. Phys. Commun. 176 (2007) 300 [hep-ph/0609017] [INSPIRE].
[21]
I. Antcheva et al., ROOT: A C++ framework for petabyte data storage, statistical analysis and visualization, Comput. Phys. Commun. 180 (2009) 2499 [arXiv:1508.07749] [INSPIRE].ADSCrossRefGoogle Scholar
[22]
A. Denner, S. Dittmaier, S. Kallweit and S. Pozzorini, NLO QCD corrections to WWbb production at hadron colliders, Phys. Rev. Lett. 106 (2011) 052001 [arXiv:1012.3975] [INSPIRE].ADSCrossRefGoogle Scholar
[23]
G. Bevilacqua, M. Czakon, A. van Hameren, C.G. Papadopoulos and M. Worek, Complete off-shell effects in top quark pair hadroproduction with leptonic decay at next-to-leading order, JHEP 02 (2011) 083 [arXiv:1012.4230] [INSPIRE].ADSCrossRefGoogle Scholar
[24]
A. Denner, S. Dittmaier, S. Kallweit and S. Pozzorini, NLO QCD corrections to off-shell top-antitop production with leptonic decays at hadron colliders, JHEP 10 (2012) 110 [arXiv:1207.5018] [INSPIRE].ADSCrossRefGoogle Scholar
[25]
R. Frederix, Top Quark Induced Backgrounds to Higgs Production in the WW (*) → llνν Decay Channel at Next-to-Leading-Order in QCD, Phys. Rev. Lett. 112 (2014) 082002 [arXiv:1311.4893] [INSPIRE].ADSCrossRefGoogle Scholar
[26]
G. Heinrich, A. Maier, R. Nisius, J. Schlenk and J. Winter, NLO QCD corrections to \( {W}^{+}{W}^{-}b\overline{b} \) production with leptonic decays in the light of top quark mass and asymmetry measurements, JHEP 06 (2014) 158 [arXiv:1312.6659] [INSPIRE].ADSCrossRefGoogle Scholar
[27]
A. Denner and M. Pellen, Off-shell production of top-antitop pairs in the lepton+jets channel at NLO QCD, JHEP 02 (2018) 013 [arXiv:1711.10359] [INSPIRE].ADSCrossRefGoogle Scholar
[28]
A. Denner and R. Feger, NLO QCD corrections to off-shell top-antitop production with leptonic decays in association with a Higgs boson at the LHC, JHEP 11 (2015) 209 [arXiv:1506.07448] [INSPIRE].ADSCrossRefGoogle Scholar
[29]
G. Bevilacqua, H.B. Hartanto, M. Kraus and M. Worek, Top Quark Pair Production in Association with a Jet with Next-to-Leading-Order QCD Off-Shell Effects at the Large Hadron Collider, Phys. Rev. Lett. 116 (2016) 052003 [arXiv:1509.09242] [INSPIRE].ADSCrossRefGoogle Scholar
[30]
G. Bevilacqua, H.B. Hartanto, M. Kraus and M. Worek, Off-shell Top Quarks with One Jet at the LHC: A comprehensive analysis at NLO QCD, JHEP 11 (2016) 098 [arXiv:1609.01659] [INSPIRE].ADSCrossRefGoogle Scholar
[31]
A. Denner and M. Pellen, NLO electroweak corrections to off-shell top-antitop production with leptonic decays at the LHC, JHEP 08 (2016) 155 [arXiv:1607.05571] [INSPIRE].ADSCrossRefGoogle Scholar
[32]
A. Denner, J.-N. Lang, M. Pellen and S. Uccirati, Higgs production in association with off-shell top-antitop pairs at NLO EW and QCD at the LHC, JHEP 02 (2017) 053 [arXiv:1612.07138] [INSPIRE].ADSCrossRefGoogle Scholar
[33]
C.G. Papadopoulos and M. Worek, Multi-parton cross sections at hadron colliders, Eur. Phys. J. C 50 (2007) 843 [hep-ph/0512150] [INSPIRE].
[34]
M. Czakon, C.G. Papadopoulos and M. Worek, Polarizing the Dipoles, JHEP 08 (2009) 085 [arXiv:0905.0883] [INSPIRE].ADSCrossRefGoogle Scholar
[35]
A. Cafarella, C.G. Papadopoulos and M. Worek, Helac-Phegas: A Generator for all parton level processes, Comput. Phys. Commun. 180 (2009) 1941 [arXiv:0710.2427] [INSPIRE].ADSCrossRefGoogle Scholar
[36]
C.G. Papadopoulos, PHEGAS: A Phase space generator for automatic cross-section computation, Comput. Phys. Commun. 137 (2001) 247 [hep-ph/0007335] [INSPIRE].
[37]
A. van Hameren, PARNI for importance sampling and density estimation, Acta Phys. Polon. B 40 (2009) 259 [arXiv:0710.2448] [INSPIRE].ADSGoogle Scholar
[38]
A. van Hameren, Kaleu: A General-Purpose Parton-Level Phase Space Generator, arXiv:1003.4953 [INSPIRE].
[39]
P. Nogueira, Automatic Feynman graph generation, J. Comput. Phys. 105 (1993) 279 [INSPIRE].ADSMathSciNetCrossRefzbMATHGoogle Scholar
[40]
S. Badger, B. Biedermann and P. Uwer, NGluon: A Package to Calculate One-loop Multi-gluon Amplitudes, Comput. Phys. Commun. 182 (2011) 1674 [arXiv:1011.2900] [INSPIRE].ADSCrossRefzbMATHGoogle Scholar
[41]
A. van Hameren, C.G. Papadopoulos and R. Pittau, Automated one-loop calculations: A Proof of concept, JHEP 09 (2009) 106 [arXiv:0903.4665] [INSPIRE].ADSMathSciNetCrossRefGoogle Scholar
[42]
G. Ossola, C.G. Papadopoulos and R. Pittau, CutTools: A Program implementing the OPP reduction method to compute one-loop amplitudes, JHEP 03 (2008) 042 [arXiv:0711.3596] [INSPIRE].ADSCrossRefGoogle Scholar
[43]
G. Bevilacqua, M. Czakon, M.V. Garzelli, A. van Hameren, A. Kardos, C.G. Papadopoulos et al., HELAC-NLO, Comput. Phys. Commun. 184 (2013) 986 [arXiv:1110.1499] [INSPIRE].ADSCrossRefGoogle Scholar
[44]
G. Ossola, C.G. Papadopoulos and R. Pittau, Reducing full one-loop amplitudes to scalar integrals at the integrand level, Nucl. Phys. B 763 (2007) 147 [hep-ph/0609007] [INSPIRE].
[45]
G. Ossola, C.G. Papadopoulos and R. Pittau, On the Rational Terms of the one-loop amplitudes, JHEP 05 (2008) 004 [arXiv:0802.1876] [INSPIRE].ADSMathSciNetCrossRefGoogle Scholar
[46]
P. Draggiotis, M.V. Garzelli, C.G. Papadopoulos and R. Pittau, Feynman Rules for the Rational Part of the QCD 1-loop amplitudes, JHEP 04 (2009) 072 [arXiv:0903.0356] [INSPIRE].ADSMathSciNetCrossRefGoogle Scholar
[47]
A. Denner, S. Dittmaier, M. Roth and D. Wackeroth, Predictions for all processes e + e − → 4 fermions + γ, Nucl. Phys. B 560 (1999) 33 [hep-ph/9904472] [INSPIRE].
[48]
A. Denner, S. Dittmaier, M. Roth and L.H. Wieders, Electroweak corrections to charged-current e + e − → 4 fermion processes: Technical details and further results, Nucl. Phys. B 724 (2005) 247 [Erratum ibid. B 854 (2012) 504] [hep-ph/0505042] [INSPIRE].
[49]
A. van Hameren, OneLOop: For the evaluation of one-loop scalar functions, Comput. Phys. Commun. 182 (2011) 2427 [arXiv:1007.4716] [INSPIRE].ADSCrossRefzbMATHGoogle Scholar
[50]
S. Catani and M.H. Seymour, A General algorithm for calculating jet cross-sections in NLO QCD, Nucl. Phys. B 485 (1997) 291 [Erratum ibid. B 510 (1998) 503] [hep-ph/9605323] [INSPIRE].
[51]
S. Catani, S. Dittmaier, M.H. Seymour and Z. Trócsányi, The Dipole formalism for next-to-leading order QCD calculations with massive partons, Nucl. Phys. B 627 (2002) 189 [hep-ph/0201036] [INSPIRE].
[52]
G. Bevilacqua, M. Czakon, M. Kubocz and M. Worek, Complete Nagy-Soper subtraction for next-to-leading order calculations in QCD, JHEP 10 (2013) 204 [arXiv:1308.5605] [INSPIRE].ADSCrossRefGoogle Scholar
[53]
S. Frixione, Z. Kunszt and A. Signer, Three jet cross-sections to next-to-leading order, Nucl. Phys. B 467 (1996) 399 [hep-ph/9512328] [INSPIRE].
[54]
Z. Nagy and Z. Trócsányi, Next-to-leading order calculation of four jet observables in electron positron annihilation, Phys. Rev. D 59 (1999) 014020 [Erratum ibid. D 62 (2000) 099902] [hep-ph/9806317] [INSPIRE].
[55]
Z. Nagy, Next-to-leading order calculation of three jet observables in hadron hadron collision, Phys. Rev. D 68 (2003) 094002 [hep-ph/0307268] [INSPIRE].
[56]
J.M. Campbell and F. Tramontano, Next-to-leading order corrections to Wt production and decay, Nucl. Phys. B 726 (2005) 109 [hep-ph/0506289] [INSPIRE].
[57]
G. Bevilacqua, M. Czakon, C.G. Papadopoulos, R. Pittau and M. Worek, Assault on the NLO Wishlist: \( pp\to t\overline{t}b\overline{b} \), JHEP 09 (2009) 109 [arXiv:0907.4723] [INSPIRE].ADSCrossRefGoogle Scholar
[58]
M. Czakon, H.B. Hartanto, M. Kraus and M. Worek, Matching the Nagy-Soper parton shower at next-to-leading order, JHEP 06 (2015) 033 [arXiv:1502.00925] [INSPIRE].ADSCrossRefGoogle Scholar
[59]
M. Jezabek and J.H. Kuhn, QCD Corrections to Semileptonic Decays of Heavy Quarks, Nucl. Phys. B 314 (1989) 1 [INSPIRE].ADSCrossRefGoogle Scholar
[60]
M. Czakon and A. Mitov, Top++: A Program for the Calculation of the Top-Pair Cross-Section at Hadron Colliders, Comput. Phys. Commun. 185 (2014) 2930 [arXiv:1112.5675] [INSPIRE].ADSCrossRefGoogle Scholar
[61]
S. Dulat, T.-J. Hou, J. Gao, M. Guzzi, J. Huston, P. Nadolsky et al., New parton distribution functions from a global analysis of quantum chromodynamics, Phys. Rev. D 93 (2016) 033006 [arXiv:1506.07443] [INSPIRE].ADSGoogle Scholar
[62]
M. Cacciari, G.P. Salam and G. Soyez, The anti-k t jet clustering algorithm, JHEP 04 (2008) 063 [arXiv:0802.1189] [INSPIRE].ADSCrossRefzbMATHGoogle Scholar
[63]
S. Frixione, Isolated photons in perturbative QCD, Phys. Lett. B 429 (1998) 369 [hep-ph/9801442] [INSPIRE].
[64]
J. Butterworth et al., PDF4LHC recommendations for LHC Run II, J. Phys. G 43 (2016) 023001 [arXiv:1510.03865] [INSPIRE].ADSCrossRefGoogle Scholar
[65]
L.A. Harland-Lang, A.D. Martin, P. Motylinski and R.S. Thorne, Parton distributions in the LHC era: MMHT 2014 PDFs, Eur. Phys. J. C 75 (2015) 204 [arXiv:1412.3989] [INSPIRE].ADSCrossRefGoogle Scholar
[66]
NNPDF collaboration, R.D. Ball et al., Parton distributions for the LHC Run II, JHEP 04 (2015) 040 [arXiv:1410.8849] [INSPIRE].
[67]
SM MC Working Group, SM and NLO MULTILEG Working Group collaboration, J. Alcaraz Maestre et al., The SM and NLO Multileg and SM MC Working Groups: Summary Report, in proceedings of 7th Les Houches Workshop on Physics at TeV Colliders, Les Houches, France, 30 May – 17 June 2011, pp. 1–220, http://lss.fnal.gov/archive/preprint/fermilab-pub-12-885-cd.shtml, arXiv:1203.6803 [INSPIRE].
[68]
G. Heinrich, A. Maier, R. Nisius, J. Schlenk, M. Schulze, L. Scyboz et al., NLO and off-shell effects in top quark mass determinations, JHEP 07 (2018) 129 [arXiv:1709.08615] [INSPIRE].ADSCrossRefGoogle Scholar
[69]
G. Bevilacqua, H.B. Hartanto, M. Kraus, M. Schulze and M. Worek, Top quark mass studies with \( t\overline{t}j \) at the LHC, JHEP 03 (2018) 169 [arXiv:1710.07515] [INSPIRE].CrossRefGoogle Scholar
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Authors and Affiliations
G. Bevilacqua1H. B. Hartanto2M. Kraus3T. Weber4M. Worek4Email authorView author's OrcID profile1.MTA-DE Particle Physics Research GroupUniversity of DebrecenDebrecenHungary2.Institute for Particle Physics Phenomenology, Department of PhysicsDurham UniversityDurhamU.K.3.Humboldt-Universität zu Berlin, Institut für PhysikBerlinGermany4.Institute for Theoretical Particle Physics and CosmologyRWTH Aachen UniversityAachenGermany