Higgs Bosons, Heavy Quarks and Soft Gluons: Resummation-Improved Predictions for Associated Higgs Production Processes at the LHC
Final Report Abstract
The Standard Model (SM) of particle physics summarises our current understanding of matter and its interactions. While it is known that the SM does not provide a complete description of nature, no physics beyond the SM (BSM) has been observed to date at the Large Hadron Collider (LHC). Correspondingly, the focus at the LHC has shifted from searching for direct signs of new physics to looking for deviations from theoretical predictions in the measured data. In this context, among various processes studied at the LHC, those involving top quarks and/or Higgs bosons command particular attention. The Higgs boson, discovered at the LHC in 2012, remains the least known component of the SM. The top quark is the heaviest known fundamental particle, much more massive than other quarks. Detailed investigations of the properties of the top quark and the Higgs boson, in particular their coupling, as well as couplings to other SM particles, are imperative for consistency checks of the SM, and, consequently, for shedding light on the nature of BSM physics. On the theoretical side, such investigations call for increased precision of the calculations for the processes involving top quark and Higgs boson production at the LHC. In this project, the worldwide most precise theoretical predictions for processes involving top quarks and Higgs bosons have been obtained. In particular, the project focused on a class of 2 → 3 processes at the LHC, i.e. processes that involve three particles in the final state. To this class of processes belongs the associated top quark-pair production together with a Higgs boson, or together with a gauge boson such as the carriers of the electroweak interactions, the Z and W bosons. Another example of such a process, also studied in this project, is the single top quark and Higgs production in association with a jet. The precision has been improved by considering (or ”resumming”) effects of additional emission of any number of low-energetic (”soft”) or collinear gluons by the colour-charged particles involved in the process. Within the scope of the project, a series of innovative and pioneering calculations for the associated top quark production with a boson has been undertaken and successfully completed. They enabled, for the first time, numerical predictions for the resummed cross section in the direct QCD approach for a 2 → 3 process with more than 3 legs carrying colour, first at the NLO+NLL accuracy, later extended to NLO+NNLL. The threshold-resummed results led to remarkable improvements in the stability and the precision of predictions for the associated processes. The obtained results are the worldwide most precise theoretical predictions for processes involving top quarks and Higgs bosons, as well as top quarks and Z bosons. These state-of-the-art predictions are currently used by ATLAS and CMS collaborations in their analysis and provide theory benchmarks for comparison with experiment.
Publications
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Soft gluon resummation at fixed invariant mass for associated $t\bar{t}H$ production at the LHC. Proceedings of Fourth Annual Large Hadron Collider Physics — PoS(LHCP2016), 084.
Theeuwes, Vincent; Kulesza, Anna; Motyka, Leszek & Stebel, Tomasz
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Soft gluon resummation for associated t t ¯ H $$ \mathrm{t}\overline{\mathrm{t}}\mathrm{H} $$ production at the LHC. Journal of High Energy Physics, 2016(3).
Kulesza, Anna; Motyka, Leszek; Stebel, Tomasz & Theeuwes, Vincent
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Threshold resummation for hadronic collisions with three particles in the final state. Proceedings of 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for the LHC and Future Colliders) — PoS(RADCOR2015), 042.
Kulesza, Anna; Motyka, Leszek; Stebel, Tomasz & Theeuwes, Vincent
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Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector, CERN Yellow Reports: Monographs series. Geneva, Switzerland. CERN Publishing.
D. de Florian et al. [LHC Higgs Cross Section Working Group]
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Associated tt¯H production at the LHC: Theoretical predictions at NLO+NNLL accuracy. Physical Review D, 97(11).
Kulesza, Anna; Motyka, Leszek; Stebel, Tomasz & Theeuwes, Vincent
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Improving predictions for associated $t\bar{t}H$ production at the LHC: soft gluon resummation through NNLL accuracy. Proceedings of The European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2017), 339.
Stebel, Tomasz; Kulesza, Anna; Motyka, Leszek & Theeuwes, Vincent
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Soft gluon resummation for the associated production of a top quark pair with a W boson at the LHC. Proceedings of The European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2017), 465.
Schwartländer, Daniel; Kulesza, Anna; Motyka, Leszek; Stebel, Tomasz & Theeuwes, Vincent
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Associate production of a $H, W or Z$ with a $t\bar{t}$ pair at the LHC: theoretical predictions at NLO+NNLL. Proceedings of Corfu Summer Institute 2018 "School and Workshops on Elementary Particle Physics and Gravity" — PoS(CORFU2018), 024.
Kulesza, Anna; Motyka, Leszek; Schwartländer, Daniel; Stebel, Tomasz & Theeuwes, Vincent
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Associated production of a top quark pair with a heavy electroweak gauge boson at NLO+NNLL accuracy. The European Physical Journal C, 79(3).
Kulesza, Anna; Motyka, Leszek; Schwartländer, Daniel; Stebel, Tomasz & Theeuwes, Vincent
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Associated top quark pair production with a heavy boson: differential cross sections at NLO + NNLL accuracy. The European Physical Journal C, 80(5).
Kulesza, Anna; Motyka, Leszek; Schwartländer, Daniel; Stebel, Tomasz & Theeuwes, Vincent
