QCD predictions for event-shape distributions in hadronic Higgs decays

We consider associated Zh production with Z → ℓ+ℓ− and $$ h\to b\overline{b} $$ h → b b ¯ decays in hadronic collisions. In the framework of the Standard Model effective field theory (SMEFT) we calculate the QCD corrections to this process and achieve next-to-next-to-leading order plus parton shower (NNLO+PS) accuracy using the MiNNLOPS method. This precision is obtained for a subset of six SMEFT operators, including the corrections from effective Yukawa- and chromomagnetic dipole-type interactions. Missing higher-order QCD effects associated with the considered dimension-six operators are estimated to have a relative numerical impact of less than a percent on the total rate once existing experimental limits on the relevant Wilson coefficients are taken into account. We provide a dedicated Monte Carlo (MC) code that evaluates the NNLO SMEFT corrections on-the-fly in the event generation. This MC generator is used to study the numerical impact of NNLO+PS corrections on the kinematic distributions in $$ pp\to Zh\to {\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-}b\overline{b} $$ pp → Zh → ℓ + ℓ − b b ¯ production employing simple SMEFT benchmark scenarios. We identify the invariant mass $$ {m}_{b\overline{b}} $$ m b b ¯ of the two b-tagged jets as well as the three-invariant jet mass $$ {m}_{b\overline{b}j} $$ m b b ¯ j as particularly interesting observables to study SMEFT effects. These distributions receive contributions that change both their normalisation and shape with the latter modifications depending on the exact jet definition. To our knowledge SMEFT effects of this type have so far not been discussed in the literature. The presented MC generator can also serve as a starting point to obtain NNLO+PS accuracy for a suitable enlarged set of effective operators in the future.

Section: Inclusive H → B B Decay In the Smeftsupporting

confidence: 78%

Section: Inclusive H → B B Decay In the Smeftmentioning

confidence: 99%

“…We will also comment on how our results are modified if the other two resolved regions, i.e. p T,Z ∈ [75,150] GeV and p T,Z > 250 GeV, are considered.…”

Section: Inclusive H → B B Decay In the Smeftmentioning

confidence: 99%

“…At future e + e − colliders it might be possible to exploit global event-shape variables in the h → b b decay[75] to put constraints on the Wilson coefficient c bG .…”

mentioning

confidence: 99%

See 2 more Smart Citations

NNLO event generation for $$ pp\to Zh\to {\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-}b\overline{b} $$ production in the SM effective field theory

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et al. 2022

Four-jet event shapes in hadronic Higgs decays

Gehrmann-De Ridder,

Preuss,

Williams

2024

We present next-to-leading order perturbative QCD predictions for four-jet-like event-shape observables in hadronic Higgs decays. To this end, we take into account two Higgs-decay categories: involving either the Yukawa-induced decay to a $${\text{b}}\overline{{\text{b}} }$$ pair or the loop-induced decay to two gluons via an effective Higgs-gluon-gluon coupling. We present results for distributions related to the event-shape variables thrust minor, light-hemisphere mass, narrow jet broadening, D-parameter, and Durham four-to-three-jet transition variable. For each of these observables we study the impact of higher-order corrections and compare their size and shape in the two Higgs-decay categories. We find large NLO corrections with a visible shape difference between the two decay modes, leading to a significant shift of the peak in distributions related to the H → gg decay mode.

NLO+NLL′ accurate predictions for three-jet event shapes in hadronic Higgs decays

Gehrmann-De Ridder,

Preuss,

Reichelt

et al. 2024

We present resummed predictions at next-to-leading logarithmic accuracy matched to the exact next-to-leading order results for a set of classical event-shape observables in hadronic Higgs decays, i.e., for the channels H → gg and H → $$ b\overline{b} $$ b b ¯ . We furthermore consider soft-drop grooming of the hadronic final states and derive corresponding NLO+NLL′ predictions for the groomed thrust observable. Differences in the QCD radiation pattern of gluon- and quark-initiated final states are imprinted in the event-shape distributions, offering separation power for the two decay channels. In particular, we show that ungroomed event shapes in H → gg decays develop a considerably harder spectrum than in H → $$ b\overline{b} $$ b b ¯ decays. We highlight that soft-drop grooming can substantially alter this behaviour, unless rather inclusive grooming parameters are chosen.