Searches for invisible decays of the Higgs boson in pp collisions at s $$ \sqrt{s} $$ = 7, 8, and 13 TeV

Abstract

Searches for invisible decays of the Higgs boson are presented. The data collected with the CMS detector at the LHC correspond to integrated luminosities of 5.1, 19.7, and 2.3 fb −1 at centre-of-mass energies of 7, 8, and 13 TeV, respectively. The search channels target Higgs boson production via gluon fusion, vector boson fusion, and in association with a vector boson. Upper limits are placed on the branching fraction of the Higgs boson decay to invisible particles, as a function of the assumed production cross sections. The combination of all channels, assuming standard model production, yields an observed (expected) upper limit on the invisible branching fraction of 0.24 (0.23) at the 95% confidence level. The results are also interpreted in the context of Higgs-portal dark matter models. [6,7]. More generally, invisible Higgs boson decays can be realised through interactions between the Higgs boson and dark matter (DM) [8]. In Higgs-portal models [9][10][11][12], the Higgs boson acts as a mediator between SM and DM particles allowing for direct production of DM at the LHC. Furthermore, cosmological models proposing that the Higgs boson played a central role in the evolution of the early universe motivate the study of the relationship between the Higgs boson and DM [13, 14].Direct searches for invisible decays of the Higgs boson increase the sensitivity to the invisible Higgs boson width beyond the indirect constraints. The typical signature at the LHC is a large missing transverse momentum recoiling against a distinctive visible system. Previous searches by the ATLAS and CMS Collaborations have targeted Higgs boson production in association with a vector boson (VH, where V denotes W or Z) [15][16][17] or with jets consistent with a vector boson fusion (VBF, via qq → qqH) topology [17, 18]. A combination of direct searches for invisible Higgs boson decays in qqH and VH production, by the ATLAS Collaboration, yields an upper limit of 0.25 on the Higgs boson invisible branching fraction, B(H → inv), at the 95% confidence level [19]. Additionally, searches by the ATLAS Collaboration for DM in events with missing transverse momentum accompanied by jets have been interpreted in the context of Higgs boson production via gluon fusion and subsequent decay to invisible particles [20].In this paper, results from a combination of searches for invisible decays of the Higgs boson using data collected during 2011, 2012, and 2015 are presented. The searches target the qqH, VH, and ggH production modes. The searches for the VH production mode include searches targeting ZH production, in which the Z boson decays to a pair of leptons (either e + e − or µ + µ − ) or bb, and searches for both the ZH and WH production modes, in which the W or Z boson decays to light-flavour jets. Additional sensitivity is achieved in this analysis by including a search targeting gluon fusion production where the Higgs boson is produced accompanied by a gluon jet (gg → gH). The diagrams for the qqH, VH, and ggH Higgs boson production pr...

Charged composite scalar dark matter

“…(3.1) below), which is expected to be very small in the light χ scenario. The current 95% CL lower bound of BR(h → χ * χ) < 0.24 [26] translates into f 1.2 TeV.…”

Universal properties of pseudoscalar mediators in dark matter extensions of 2HDMs

“…Here, σ prod denotes the production cross section, Γ(h → X) the partial decay width of the Higgs into the final state X and Γ h the total width of the Higgs predictions are denoted by the superscript SM. An additional constraint arises from the bound on invisible Higgs decays Br(h → invisible) < 0.23 [31,32] …”

The minimal fermionic model of electroweak baryogenesis

“…For instance, in the custodial symmetric limit the lightest neutral singlet-doublet fermion does not couple to the Z. There is a more important limit on neutral singlet-doublet fermions if they have a Yukawa coupling to the Higgs of the order of the bottom Yukawa or larger, coming from the Higgs invisible width measurement [63,64], which basically rules out neutral singlet-doublet fermions below half the Higgs mass. The high luminosity LHC will be able to probe pair production of neutral singlet-doublet fermions if they are mostly doublet up to ∼ 100 GeV even in the compressed region, from searches assisted by the emission of an initial state radiation jet [65].…”