Decays of a NMSSM CP-odd Higgs in the low-mass region

Abstract

A popular regime in the NMSSM parameter space involves a light CP-odd Higgs A 1 . This scenario has consequences for e.g. light singlino Dark Matter annihilating in the A 1 -funnel. In order to confront the pseudoscalar to experimental limits such as flavour observables, Upsilon decays or Beam-Dump experiments, it is necessary to control the interactions of this particle with hadronic matter and derive the corresponding decays. The partonic description cannot be relied upon for masses close to m A 1 ∼ 1 GeV and we employ a chiral lagrangian, then extended to a spectator model for somewhat larger masses, to describe the interplay of the CP-odd Higgs with hadrons. Interestingly, a mixing can develop between A 1 and neutral pseudoscalar mesons, leading to substantial hadronic decays and a coupling of A 1 to the chiral anomaly. Additionally, quartic A 1 -meson couplings induce tri-meson decays of the Higgs pseudoscalar. We investigate these effects and propose an estimate of the Higgs widths for masses below m A 1 3 GeV. While we focus on the case of the NMSSM, our results are applicable to a large class of models.

Decays of the neutral Higgs bosons into SM fermions and gauge bosons in the $\mathcal{CP}$-violating NMSSM

“…Improved descriptions of the hadronic decays of Higgs states close to the b b threshold or in the chiral limit have been presented in e. g. Refs. [74][75][76][106][107][108].…”

“…However, we stress that we strictly confine ourselves to the free-particle approximation for the final states. Accordingly, dedicated analyses would be needed for a proper treatment of decays close to threshold, since finite-width effects need to be taken into account in this region, and effects of the interactions among the final states can be very large [72][73][74][75][76].…”

Revisiting singlino dark matter of the natural Z3-symmetric NMSSM in the light of LHC

“…Also, these facilitate the simultaneous opening up of the decays χ 0 2,3 → χ 0 1 h 2 (h SM ) thus reinforcing the combined branching fractions of χ 0 2,3 to Higgs bosons over the same to Z-boson. Some specific consequences of such possibilities had been studied in the past which include rather light scalars decaying to (i) ττ and leading to soft multi-lepton final state [40], (ii) bb [41] and (iii) two photons [42,43]. For m a 1 1 GeV, even mesons can be produced out of a boosted pair of light quarks that a 1 /h 1 might decay to.…”

FASER’s physics reach for long-lived particles

“…For the hadronic and photonic branching ratios, we adopt the recent results of Ref. [97], 3 in which the hadronic decay widths were estimated employing the chiral Lagrangian for m a 1 GeV and using the spectator model for larger masses. For even larger masses m a > 3 GeV, we estimate the hadronic decay width through the partonic width into…”