Updated constraints from radiative Υ decays on a light CP-odd Higgs

Abstract

The possible existence of a light CP-odd Higgs state in many new-physics models could lead to observable effects in the bottomonium sector. Experimental bounds on radiative Υ decays through such a pseudoscalar state and possible mixings with the η 0 b states are reviewed. Combining these two effects, we set constraints on the properties of the CP-odd Higgs in the limit of small photon energy of BR(Υ → γ τ + τ − ), that is on the pseudoscalar mass-range ∼ 8 − 10 GeV.

Lattice QCD study of the radiative decays J/ψ → η c γ and h c → η c γ

“…Within the uncertainties quoted above, both our form factors are insensitive to the change of the sea quark mass. After combining our F 1 (0) with the measured Br(h c → η c γ) we deduced the value of the width, Γ hc = 1.37 (22) MeV.…”

Reduced branching ratio for H → AA → 4 τ from A − η b mixing

“…The origin is a reduced BR(A → τ + τ − ) caused by A − η b (nS) mixing, leading to dominant hadronic decays of the physical eigenstates. This window for M A is of particular interest, since it contains the region in which the tension between the observed η b (1S) mass and its prediction based on QCD can be resolved [22,33] through this mixing. We emphasize that we did not make particular assumptions on the SU(2) doublet component cos θ A , on tan β or on the coupling X d (see (1.1)) of A to b quarks since, at least for small mixing angles, X 2 d cancels out in the expression (2.5) for the BR(η i → τ + τ − ) for the mass eigenstates.…”

“…Moreover, dominant hadronic decays of the mass eigenstate η i would also handicap searches for A via central exclusive production [46] at hadron colliders, or via the µ + µ − final state as proposed in [47] and studied, using early LHC data, in [48]. It remains to look for A in radiative Υ decays, but corresponding searches have also to be interpreted carefully taking mixing effects into account [19][20][21]33].…”

“…Notably for M A 1 below the 2 τ threshold, where A 1 has a large branching fraction into two muons, these bounds are quite strong and imply X d < ∼ 0.5. Upper bounds on X d for 8 GeV < ∼ M A 1 < ∼ 10.1 GeV, including effects from η b (nS) − A 1 mixing, have recently been investigated in [33], implying X d < ∼ 2 . .…”

NMSSM interpretations of the observed Higgs signal

“…• limits from the bottomonium sector: non-observation of a signal in BR(Υ → γA → γl + l − ), excessive contribution to the η b (1S)-A mixing [99][100][101]. Only light CP-odd Higgs below ∼ 10 GeV are concerned by these constraints and the limits are kept as a 95% C.L.…”