Measurement of VH, $$ \mathrm{H}\to \mathrm{b}\overline{\mathrm{b}} $$ production as a function of the vector-boson transverse momentum in 13 TeV pp collisions with the ATLAS detector

Abstract

Measurement of V H, H → bb production as a function of the vector-boson transverse momentum in 13 TeV p p collisions with the ATLAS detectorThe ATLAS Collaboration Cross-sections of associated production of a Higgs boson decaying into bottom-quark pairs and an electroweak gauge boson, W or Z, decaying into leptons are measured as a function of the gauge boson transverse momentum. The measurements are performed in kinematic fiducial volumes defined in the 'simplified template cross-section' framework. The results are obtained using 79.8 fb −1 of proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. All measurements are found to be in agreement with the Standard Model predictions, and limits are set on the parameters of an effective Lagrangian sensitive to modifications of the Higgs boson couplings to the electroweak gauge bosons.A particle consistent with the Standard Model (SM) predictions for the Higgs boson [1][2][3][4] was observed in 2012 by the ATLAS and CMS collaborations [5, 6] at the LHC. Further analysis of ATLAS and CMS data collected in proton-proton (pp) collisions at centre-of-mass energies of 7 TeV, 8 TeV and 13 TeV in two LHC data-taking periods (Runs 1 and 2) has led to precise measurements of the mass of this particle (around 125 GeV) [7-9], tests of its spin and parity (J P = 0 + ) against alternative hypotheses [10, 11], as well as to measurements of its production and decay rates [12][13][14].Recently, experiments at the LHC observed Higgs boson production in association with weak gauge bosons V = W, Z (V H production) [15] and Higgs boson decays into pairs of bottom quarks (H → bb) [15, 16]. With these results, the four most important Higgs boson production modes predicted by the SM, gluon-gluon fusion (ggF), vector-boson fusion (VBF), and associated production of a Higgs boson with either a weak gauge boson (V H) or a top-quark pair (ttH) are established. Similarly, several of the main modes of Higgs boson decays into fermionic (bb, ττ) and bosonic (WW, Z Z, γγ) final states are observed. All results, typically expressed in the form of 'signal strengths', defined as the ratio of the observed to the expected product of the production cross-section times branching ratio into a certain final state, are consistent with SM predictions within uncertainties.To probe the kinematic properties of Higgs boson production in more detail, to reduce the impact of theoretical uncertainties on the measurements and to make the measurements easier to compare with future updated calculations, the framework of simplified template cross-sections (STXS) has been introduced [17, 18]. In this framework, the cross-sections for the various Higgs boson production modes are measured in exclusive regions carefully defined by fiducial selections based on the kinematic properties of Higgs boson production. The extrapolation from the phase space selected by the analysis criteria to that for which the cross-section measurements are presented is thus red...

Benchmarking simplified template cross sections in W H production

“…7. Results using this approach have recently been presented by ATLAS [56] using the 0-jet, single lepton data sample, to obtain limits on anomalous couplings, assuming only one non-zero Wilson coefficient at a time. Unfortunately, they do not consider the most interesting 4-point vertex from O Hq , for which boosted V H production provides the strongest constraints [9].…”

Higgs production in the VH mode at ATLAS and CMS

“…This combination led to the observation of the VH production mode with an observed (expected) significance of 5.3 (4.8) standard deviations (σ ). The ATLAS collaboration also provided the first reinterpretation of the VH(H → bb) results in the context of the Simplified Template Cross-Section framework [19], measuring the production cross-section in bins of p T (V) separately for the WH and ZH modes. Indeed, modification of the cross-section in bins of p T (V) could highlight the contribution from new physics phenomena.…”

Higgs boson couplings and properties

“…fraction of the VH(bb) process in exclusive regions of the vector boson p T [20]. Sensitivity to the transverse momentum is retained through the shape of the boosted decision tree discriminant that is used to separate the signal from the multijet background, and templates for two (three) intervals of the W (Z) boson p T are simultaneously fit to the data.…”

“…Right: measurement performed in two (three) exclusive intervals of the W (Z) transverse momentum. Both figures are taken from[20].…”