Associated production of a Higgs boson decaying into bottom quarks and a weak vector boson decaying leptonically at NNLO in QCD

TL;DR

This paper calculates precise NNLO QCD corrections for Higgs production with a decay into bottom quarks and a leptonically decaying vector boson, providing accurate predictions for LHC observables.

Contribution

It presents the first fully differential NNLO QCD calculation for associated Higgs and vector boson production including decay, using antenna subtraction and implementing in NNLOJET.

Findings

Percent-level accuracy in fiducial cross sections and distributions.

Residual scale uncertainties are quantified with independent variations.

Naive perturbative expansion may underestimate higher-order effects at NNLO.

Abstract

We present the calculation of next-to-next-to-leading order (NNLO) corrections in perturbative QCD for the production of a Higgs boson decaying into a pair of bottom quarks in association with a leptonically decaying weak vector boson: $\mathrm{pp} \to V \mathrm{H} + X \to \ell\bar{\ell}\;\mathrm{b\bar{b}} + X$. We consider the corrections to both the production and decay sub-processes, retaining a fully differential description of the final state including off-shell propagators of the Higgs and vector boson. The calculation is carried out using the antenna subtraction formalism and is implemented in the NNLOJET framework. Clustering and identification of $\mathrm{b}$-jets is performed with the flavour-$k_t$ algorithm and results for fiducial cross sections and distributions are presented for the LHC at $\sqrt{s}=13\;\text{TeV}$. We assess the residual theory uncertainty by varying the production and decay scales independently and provide scale uncertainty bands in our results, yielding percent-level accurate predictions for observables in this Higgs production mode computed at NNLO. Confronting a na\"ive perturbative expansion of the cross section against the customary re-scaling procedure to a fixed branching ratio reveals that starting from NNLO, the latter could be inadequate in estimating missing higher-order effects through scale variations.

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