Abstract
In the context of the Standard Model effective field theory (SMEFT) we examine the constraints on the trilinear Higgs coupling that originate from off-shell Higgs production in proton-proton collisions. Our calculation of the gg → h* → ZZ → 4ℓ process includes two-loop corrections to gluon-gluon-fusion Higgs production and one-loop corrections to the Higgs propagator and its decay. Employing a matrix-element based kinematic discriminant we determine the reach of LHC Run 3 and the high-luminosity option of the LHC in constraining the relevant SMEFT Wilson coefficients. We present constraints that are not only competitive with but also complementary to the projected indirect limits that one expects to obtain from inclusive measurements of single-Higgs production processes at future LHC runs.
Highlights
Where mh 125 GeV and v 246 GeV are the Higgs mass and vacuum expectation value (VEV), respectively, and the trilinear (λ) and quartic (κ) Higgs couplings obey the relation λ
In the context of the Standard Model effective field theory (SMEFT) we examine the constraints on the trilinear Higgs coupling that originate from off-shell Higgs production in proton-proton collisions
We have studied the constraints on the trilinear Higgs coupling that originate from off-shell Higgs production in pp collisions at future LHC runs
Summary
To allow for a model-independent analysis, we work in the framework of the SMEFT [34,35,36] to parametrise the possible BSM physics entering the trilinear Higgs coupling. As the operator OT does not modify the trilinear Higgs coupling and is severely constrained through measurements of the ρ parameter describing the degree of custodial symmetry violation [41], it is irrelevant for the purpose of this work. Within these restrictions, it is sufficient to supplement the SM Lagrangian with the effective operators O6 and OH only, resulting in the following effective Lagrangian. We include cH at leading order (LO) in our numerical analysis (section 4.4), while parametrising the NLO corrections involving insertions of the Higgs trilinear coupling (section 3) solely via the Wilson coefficient c6. We will discuss separately each of these three ingredients as well as their implementation in our Monte Carlo (MC) code
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