Advertisement

Signal background interference effects in heavy scalar production and decay to a top-anti-top pair

  • B. Hespel
  • F. Maltoni
  • E. Vryonidou
Open Access
Regular Article - Theoretical Physics

Abstract

We analyse the production of a top quark pair through a heavy scalar at the LHC. We first review the main features of the signal as well as the interference with the top-anti-top background at leading order in QCD. We then study higher order QCD effects. While the background and the signal can be obtained at NNLO and NLO in QCD respectively, that is not the case for their interference, which is currently only approximately known at NLO. In order to improve the accuracy of the prediction for the interference term, we consider the effects of extra QCD radiation, i.e. the 2 → 3 (loop-induced) processes and obtain an estimate of the NLO corrections. As a result, we find that the contribution of the interference is important both at the total cross-section level and, most importantly, for the line-shape of the heavy scalar. In particular for resonances with widths larger than a couple of percent of the resonance mass, the interference term distorts the invariant mass distribution and generically leads to a non-trivial peak-dip structure. We study this process in a simplified model involving an additional scalar or pseudoscalar resonance as well as in the Two-Higgs-Doublet-Model for a set of representative benchmarks. We present the constraints on simplified models featuring an extra scalar as set by the LHC searches for top-anti-top resonances, and the implications of the 750 GeV diphoton excess recently reported by CMS and ATLAS for the top pair production assuming a scalar or a pseudoscalar resonance.

Keywords

Beyond Standard Model Heavy Quark Physics 

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. [1]
    Particle Data Group collaboration, K.A. Olive et al., Review of Particle Physics, Chin. Phys. C 38 (2014) 090001 [INSPIRE].
  2. [2]
    J.A. Aguilar-Saavedra, A Minimal set of top anomalous couplings, Nucl. Phys. B 812 (2009) 181 [arXiv:0811.3842] [INSPIRE].ADSCrossRefMATHGoogle Scholar
  3. [3]
    C. Zhang and S. Willenbrock, Effective-Field-Theory Approach to Top-Quark Production and Decay, Phys. Rev. D 83 (2011) 034006 [arXiv:1008.3869] [INSPIRE].ADSGoogle Scholar
  4. [4]
    C. Degrande, J.-M. Gerard, C. Grojean, F. Maltoni and G. Servant, Non-resonant New Physics in Top Pair Production at Hadron Colliders, JHEP 03 (2011) 125 [arXiv:1010.6304] [INSPIRE].ADSCrossRefGoogle Scholar
  5. [5]
    V. Barger, T. Han and D.G.E. Walker, Top Quark Pairs at High Invariant Mass: A Model-Independent Discriminator of New Physics at the LHC, Phys. Rev. Lett. 100 (2008) 031801 [hep-ph/0612016] [INSPIRE].
  6. [6]
    R. Frederix and F. Maltoni, Top pair invariant mass distribution: A Window on new physics, JHEP 01 (2009) 047 [arXiv:0712.2355] [INSPIRE].ADSCrossRefGoogle Scholar
  7. [7]
    CMS collaboration, Searches for new physics using the \( t\overline{t} \) invariant mass distribution in pp collisions at \( \sqrt{s}=8 \) TeV, Phys. Rev. Lett. 111 (2013) 211804 [arXiv:1309.2030] [INSPIRE].
  8. [8]
    ATLAS collaboration, A search for tt resonances using lepton-plus-jets events in proton-proton collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, JHEP 08 (2015) 148 [arXiv:1505.07018] [INSPIRE].
  9. [9]
    K.J.F. Gaemers and F. Hoogeveen, Higgs Production and Decay Into Heavy Flavors With the Gluon Fusion Mechanism, Phys. Lett. B 146 (1984) 347 [INSPIRE].ADSCrossRefGoogle Scholar
  10. [10]
    D. Dicus, A. Stange and S. Willenbrock, Higgs decay to top quarks at hadron colliders, Phys. Lett. B 333 (1994) 126 [hep-ph/9404359] [INSPIRE].
  11. [11]
    N. Craig, F. D’Eramo, P. Draper, S. Thomas and H. Zhang, The Hunt for the Rest of the Higgs Bosons, JHEP 06 (2015) 137 [arXiv:1504.04630] [INSPIRE].ADSCrossRefGoogle Scholar
  12. [12]
    S. Gori, I.-W. Kim, N.R. Shah and K.M. Zurek, Closing the Wedge: Search Strategies for Extended Higgs Sectors with Heavy Flavor Final States, Phys. Rev. D 93 (2016) 075038 [arXiv:1602.02782] [INSPIRE].ADSGoogle Scholar
  13. [13]
    A. Djouadi, J. Ellis and J. Quevillon, Interference effects in the decays of spin-zero resonances into γγ and \( t\overline{t} \), JHEP 07 (2016) 105 [arXiv:1605.00542] [INSPIRE].ADSCrossRefGoogle Scholar
  14. [14]
    ATLAS collaboration, Search for resonances decaying to photon pairs in 3.2 fb −1 of pp collisions at \( \sqrt{s}=13 \) TeV with the ATLAS detector, ATLAS-CONF-2015-081 (2015).
  15. [15]
    CMS Collaboration, Search for new physics in high mass diphoton events in proton-proton collisions at \( \sqrt{s}=13 \) TeV, CMS-PAS-EXO-15-004 (2015).
  16. [16]
    M. Czakon, P. Fiedler and A. Mitov, Total Top-Quark Pair-Production Cross Section at Hadron Colliders Through O(α S4), Phys. Rev. Lett. 110 (2013) 252004 [arXiv:1303.6254] [INSPIRE].ADSCrossRefGoogle Scholar
  17. [17]
    M. Czakon, D. Heymes and A. Mitov, High-precision differential predictions for top-quark pairs at the LHC, Phys. Rev. Lett. 116 (2016) 082003 [arXiv:1511.00549] [INSPIRE].ADSCrossRefGoogle Scholar
  18. [18]
    M. Czakon, D. Heymes and A. Mitov, Dynamical scales for multi-TeV top-pair production at the LHC, arXiv:1606.03350 [INSPIRE].
  19. [19]
    W. Bernreuther, M. Fuecker and Z.-G. Si, Weak interaction corrections to hadronic top quark pair production, Phys. Rev. D 74 (2006) 113005 [hep-ph/0610334] [INSPIRE].
  20. [20]
    D. Pagani, I. Tsinikos and M. Zaro, The impact of the photon PDF and electroweak corrections on tt distributions, Eur. Phys. J. C 76 (2016) 479 [arXiv:1606.01915] [INSPIRE].ADSCrossRefGoogle Scholar
  21. [21]
    W. Bernreuther, P. Galler, C. Mellein, Z.G. Si and P. Uwer, Production of heavy Higgs bosons and decay into top quarks at the LHC, Phys. Rev. D 93 (2016) 034032 [arXiv:1511.05584] [INSPIRE].ADSGoogle Scholar
  22. [22]
    J. Alwall et al., The automated computation of tree-level and next-to-leading order differential cross sections and their matching to parton shower simulations, JHEP 07 (2014) 079 [arXiv:1405.0301] [INSPIRE].ADSCrossRefGoogle Scholar
  23. [23]
    M.R. Buckley, D. Feld and D. Goncalves, Scalar Simplified Models for Dark Matter, Phys. Rev. D 91 (2015) 015017 [arXiv:1410.6497] [INSPIRE].ADSGoogle Scholar
  24. [24]
    P. Harris, V.V. Khoze, M. Spannowsky and C. Williams, Constraining Dark Sectors at Colliders: Beyond the Effective Theory Approach, Phys. Rev. D 91 (2015) 055009 [arXiv:1411.0535] [INSPIRE].ADSGoogle Scholar
  25. [25]
    U. Haisch and E. Re, Simplified dark matter top-quark interactions at the LHC, JHEP 06 (2015) 078 [arXiv:1503.00691] [INSPIRE].ADSCrossRefGoogle Scholar
  26. [26]
    M. Backović, M. Krämer, F. Maltoni, A. Martini, K. Mawatari and M. Pellen, Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators, Eur. Phys. J. C 75 (2015) 482 [arXiv:1508.05327] [INSPIRE].ADSCrossRefGoogle Scholar
  27. [27]
    O. Mattelaer and E. Vryonidou, Dark matter production through loop-induced processes at the LHC: the s-channel mediator case, Eur. Phys. J. C 75 (2015) 436 [arXiv:1508.00564] [INSPIRE].ADSCrossRefGoogle Scholar
  28. [28]
    P. Harris, V.V. Khoze, M. Spannowsky and C. Williams, Closing up on Dark Sectors at Colliders: from 14 to 100 TeV, Phys. Rev. D 93 (2016) 054030 [arXiv:1509.02904] [INSPIRE].ADSGoogle Scholar
  29. [29]
    C. Arina et al., A comprehensive approach to dark matter studies: exploration of simplified top-philic models, arXiv:1605.09242 [INSPIRE].
  30. [30]
    G.C. Branco, P.M. Ferreira, L. Lavoura, M.N. Rebelo, M. Sher and J.P. Silva, Theory and phenomenology of two-Higgs-doublet models, Phys. Rept. 516 (2012) 1 [arXiv:1106.0034] [INSPIRE].ADSCrossRefGoogle Scholar
  31. [31]
    D. Eriksson, J. Rathsman and O. Stal, 2HDMC: Two-Higgs-Doublet Model Calculator Physics and Manual, Comput. Phys. Commun. 181 (2010) 189 [arXiv:0902.0851] [INSPIRE].ADSCrossRefMATHGoogle Scholar
  32. [32]
    P. Bechtle, O. Brein, S. Heinemeyer, G. Weiglein and K.E. Williams, HiggsBounds: Confronting Arbitrary Higgs Sectors with Exclusion Bounds from LEP and the Tevatron, Comput. Phys. Commun. 181 (2010) 138 [arXiv:0811.4169] [INSPIRE].ADSCrossRefMATHGoogle Scholar
  33. [33]
    P. Bechtle, O. Brein, S. Heinemeyer, G. Weiglein and K.E. Williams, HiggsBounds 2.0.0: Confronting Neutral and Charged Higgs Sector Predictions with Exclusion Bounds from LEP and the Tevatron, Comput. Phys. Commun. 182 (2011) 2605 [arXiv:1102.1898] [INSPIRE].
  34. [34]
    F. Mahmoudi, SuperIso: A Program for calculating the isospin asymmetry of BK γ in the MSSM, Comput. Phys. Commun. 178 (2008) 745 [arXiv:0710.2067] [INSPIRE].ADSCrossRefMATHGoogle Scholar
  35. [35]
    F. Mahmoudi, SuperIso v2.3: A Program for calculating flavor physics observables in Supersymmetry, Comput. Phys. Commun. 180 (2009) 1579 [arXiv:0808.3144] [INSPIRE].ADSCrossRefGoogle Scholar
  36. [36]
    P. Bechtle, S. Heinemeyer, O. Stal, T. Stefaniak and G. Weiglein, HiggsSignals: Confronting arbitrary Higgs sectors with measurements at the Tevatron and the LHC, Eur. Phys. J. C 74 (2014) 2711 [arXiv:1305.1933] [INSPIRE].ADSCrossRefGoogle Scholar
  37. [37]
    O. Stål and T. Stefaniak, Constraining extended Higgs sectors with HiggsSignals, PoS(EPS-HEP 2013)314 [arXiv:1310.4039] [INSPIRE].
  38. [38]
    F. Mahmoudi and O. Stål, Flavor constraints on the two-Higgs-doublet model with general Yukawa couplings, Phys. Rev. D 81 (2010) 035016 [arXiv:0907.1791] [INSPIRE].ADSGoogle Scholar
  39. [39]
    V. Hirschi, R. Frederix, S. Frixione, M.V. Garzelli, F. Maltoni and R. Pittau, Automation of one-loop QCD corrections, JHEP 05 (2011) 044 [arXiv:1103.0621] [INSPIRE].ADSCrossRefMATHGoogle Scholar
  40. [40]
    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].
  41. [41]
    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
  42. [42]
    V. Hirschi and O. Mattelaer, Automated event generation for loop-induced processes, JHEP 10 (2015) 146 [arXiv:1507.00020] [INSPIRE].ADSCrossRefGoogle Scholar
  43. [43]
    R. Frederix et al., Higgs pair production at the LHC with NLO and parton-shower effects, Phys. Lett. B 732 (2014) 142 [arXiv:1401.7340] [INSPIRE].ADSCrossRefGoogle Scholar
  44. [44]
    B. Hespel, D. Lopez-Val and E. Vryonidou, Higgs pair production via gluon fusion in the Two-Higgs-Doublet Model, JHEP 09 (2014) 124 [arXiv:1407.0281] [INSPIRE].ADSCrossRefMATHGoogle Scholar
  45. [45]
    F. Maltoni, E. Vryonidou and M. Zaro, Top-quark mass effects in double and triple Higgs production in gluon-gluon fusion at NLO, JHEP 11 (2014) 079 [arXiv:1408.6542] [INSPIRE].ADSCrossRefGoogle Scholar
  46. [46]
    R. Frederix, S. Frixione, E. Vryonidou and M. Wiesemann, Heavy-quark mass effects in Higgs plus jets production, JHEP 08 (2016) 006 [arXiv:1604.03017] [INSPIRE].ADSCrossRefGoogle Scholar
  47. [47]
    O. Mattelaer, On the maximal use of Monte Carlo samples: re-weighting events at NLO accuracy, arXiv:1607.00763 [INSPIRE].
  48. [48]
    C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer and T. Reiter, UFO — The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201 [arXiv:1108.2040] [INSPIRE].ADSCrossRefGoogle Scholar
  49. [49]
    P. de Aquino, W. Link, F. Maltoni, O. Mattelaer and T. Stelzer, ALOHA: Automatic Libraries Of Helicity Amplitudes for Feynman Diagram Computations, Comput. Phys. Commun. 183 (2012) 2254 [arXiv:1108.2041] [INSPIRE].ADSCrossRefGoogle Scholar
  50. [50]
    S. Jung, J. Song and Y.W. Yoon, Dip or nothingness of a Higgs resonance from the interference with a complex phase, Phys. Rev. D 92 (2015) 055009 [arXiv:1505.00291] [INSPIRE].ADSGoogle Scholar
  51. [51]
    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
  52. [52]
    T. Sjöstrand, S. Mrenna and P.Z. Skands, A Brief Introduction to PYTHIA 8.1, Comput. Phys. Commun. 178 (2008) 852 [arXiv:0710.3820] [INSPIRE].
  53. [53]
    T. Sjöstrand et al., An Introduction to PYTHIA 8.2, Comput. Phys. Commun. 191 (2015) 159 [arXiv:1410.3012] [INSPIRE].
  54. [54]
    M. Spira, A. Djouadi, D. Graudenz and P.M. Zerwas, Higgs boson production at the LHC, Nucl. Phys. B 453 (1995) 17 [hep-ph/9504378] [INSPIRE].
  55. [55]
    R. Harlander and P. Kant, Higgs production and decay: Analytic results at next-to-leading order QCD, JHEP 12 (2005) 015 [hep-ph/0509189] [INSPIRE].
  56. [56]
    A. Djouadi, M. Spira and P.M. Zerwas, QCD corrections to hadronic Higgs decays, Z. Phys. C 70 (1996) 427 [hep-ph/9511344] [INSPIRE].
  57. [57]
    R.V. Harlander, S. Liebler and H. Mantler, SusHi: A program for the calculation of Higgs production in gluon fusion and bottom-quark annihilation in the Standard Model and the MSSM, Comput. Phys. Commun. 184 (2013) 1605 [arXiv:1212.3249] [INSPIRE].ADSCrossRefMATHGoogle Scholar
  58. [58]
    H. Mantler and M. Wiesemann, Hadronic Higgs production through N LO + P S in the SM, the 2HDM and the MSSM, Eur. Phys. J. C 75 (2015) 257 [arXiv:1504.06625] [INSPIRE].ADSCrossRefGoogle Scholar

Copyright information

© The Author(s) 2016

Authors and Affiliations

  1. 1.Centre for Cosmology, Particle Physics and Phenomenology (CP3)Université catholique de LouvainLouvain-la-NeuveBelgium

Personalised recommendations