η-η′ mixing determination from semileptonic D+ (s) and B+ meson decays

Abstract

In this work, we determine the degree of mixing of the η and η′ mesons from the exclusive semileptonic D+ (s) → η(′)ℓ+νℓ and B+ → η(′)ℓ+νℓ decays. A controlled parametrization of the participating hadronic form factor, D(s) → η(′) and B → η(′), in combination with experimental measurements, has allowed us to determine ϕ = 40.6(4.8)◦ and ϕ = 42.3(3.7)◦ from the analyses of differential decay width distributions and ratios of branching ratios, respectively. Our results are in good agreement with a recent determination from the Lattice QCD Extended Twisted Mass Collaboration, ϕ = 39.3(2.0)◦, and larger than the naive estimate we calculate from Chiral Perturbation Theory at leading order ϕ = 33.5◦.