Complete Higgs sector constraints on dimension-6 operators

Abstract

Constraints on the full set of Standard Model dimension-6 operators have previously used triple-gauge couplings to complement the constraints obtainable from Higgs signal strengths. Here we extend previous analyses of the Higgs sector constraints by including information from the associated production of Higgs and massive vector bosons (H+V production), which excludes a direction of limited sensitivity allowed by partial cancellations in the triple-gauge sector measured at LEP. Kinematic distributions in H+V production provide improved sensitivity to dimension-6 operators, as we illustrate here with simulations of the invariant mass and p T distributions measured by D0 and ATLAS, respectively. We provide bounds from a global fit to a complete set of CP-conserving operators affecting Higgs physics.

The effective Standard Model after LHC Run I

“…We demonstrated in previous work [89] the power of the constraints provided by measurements of kinematic distributions in V + H production at the Tevatron and the LHC, showing that measurements of the V + H invariant mass M V H at the Tevatron and the transverse momentum p V T at the LHC could close off a 'blind' direction in the parameter space of dimension-6 operator coefficients that had been allowed by previous analyses of LEP and LHC data [98]. 2 Subsequently, new data on TGCs from LHC running at 8 TeV have been published [95][96][97].…”

“…The ranges for the single-variable fits toc 3 Triple-gauge and Higgs couplings at the LHC In previous work [89] we used LHC measurements of Higgs signal strengths together with differential distributions in Higgs associated production measurements by ATLAS and D0 to constrain all the dimension-6 operators affecting Higgs physics. The associated production information was vital in eliminating a blind direction, which can also be closed by including TGC measurements.…”

“…Using the equations of motions reduces the number of independent operators [44][45][46][47][48][49], with a complete non-redundant set first categorised in [50]. This is the effective Standard Model approach adopted in a large number of recent papers 1 , and there have been many analyses of the constraints imposed on new physics via upper limits on the coefficients of a complete dimension-6 operator basis [84][85][86][87][88][89], in particular. Several different classes of measurements make important contributions to these constraints.…”

Sensitivities of prospective future e + e − colliders to decoupled new physics

“…Together with Verónica Sanz, we have previously published a global analysis of dimension-6 operators in the SM EFT [22,23], providing 95% CL ranges for their coefficients, both when each operator is switched on individually and when marginalising over the possible coefficients of all contributing operators. 3 There is currently growing interest in the physics accessible to possible future e + e − colliders that would continue the studies made with LEP and the SLC to higher energies and or luminosities [34][35][36][37][38][39][40][41][42][43][44].…”

“…Varying s 2 W between these values can therefore give an indication of the importance of these higher-order effects and is responsible, for example, for the differences between the current EWPT limits given in [22,23] and in [21]. Including consistently the effects of dimension-6 operators at the loop level would require going beyond the tree level when calculating the expansion coefficients in (3.3).…”