Higgs decay to fermion pairs at NLO in SMEFT
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Springer
Received: August 10, 2020 Accepted: October 5, 2020 Published: November 17, 2020
Jonathan M. Cullen and Benjamin D. Pecjak Institute for Particle Physics Phenomenology, Durham University, Durham DH1 3LE, U.K.
E-mail: [email protected], [email protected] Abstract: The calculation of next-to-leading order (NLO) perturbative corrections at fixed operator dimension in Standard Model Effective Field Theory (SMEFT) has been a topic of much recent interest. In this paper we obtain the NLO corrections from dimension-6 operators to the Higgs boson decays h → f f¯, where the fermions f ∈ {µ, τ, c}. This extends previous results for h → b¯b to all phenomenologically relevant Higgs boson decays into fermions, and provides the basis for future precision analyses of these decays within effective field theory. We point out the benefits of studying ratios of decay rates into different fermions in SMEFT, the most surprising of which is enhanced sensitivity to anomalous hγγ and hgg couplings induced by flavor-universal SMEFT operators, especially in scenarios where flavor-dependent Wilson coefficients are constrained by Minimal Flavor Violation. Keywords: Effective Field Theories, Higgs Physics ArXiv ePrint: 2007.15238
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP11(2020)079
JHEP11(2020)079
Higgs decay to fermion pairs at NLO in SMEFT
Contents 1 Introduction
1
2 Calculational set-up
2
3 Wilson coefficients and MFV
5 8 9 10
5 Numerical results 5.1 Decay rates at µ = mH 5.2 Scale uncertainties
12 12 14
6 Ratios of decay rates
17
7 Conclusions
20
A Decoupling constants
21
1
Introduction
Higgs decay into a fermion anti-fermion pair (h → f f¯) is a benchmark process in the Standard Model (SM). At present, the LHC has measured Higgs decays into b-quarks [1, 2] and τ -leptons [3, 4], both with an O(10%) precision, and put limits on decays into muons [5, 6] and charm quarks [7, 8]. At lepton colliders, decays into b-quarks, c-quarks, and τ -leptons should reach percent-level precision, with somewhat worse performance for decays into muons [9–13]. As measurements become more precise, h → f f¯ decays will allow the measurement of the SM Yukawa interactions and place strong constraints on non-standard Higgs couplings. Assuming that any potential new physics (NP) contributions come only from particles with masses much heavier than the electroweak (EW) scale, Standard Model Effective Theory (SMEFT) offers a model-independent, systematically improvable quantum-field theoretical framework for analyses of Higgs decays beyond the SM. One possible improvement, which has received much interest of late, is to include next-to-leading order (NLO) perturbative corrections at a fixed dimension in the operator expansion [14–41]. In [42], we built upon the results of [43, 44] to calculate the full set of NLO corrections from dimension-6 SMEFT operators to the decay rate h → b¯b. On the phenomenological side, those results provide a baseline for future precision studies
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