Exclusive rare Bs → (K, η, η ) + − decays in the light-front quark model

Using the light-front quark model, we calculate the transition form factors, decay rates and longitudinal lepton polarization asymmetries for the exclusive rare Bs → (K, η (� ) )(� + � − ,ν � ¯ ν� )( � = e, μ, τ) decays within the standard model, taking into account the η − η � mixing angle. For the mixing angle θ =− 20 ◦ (−10 ◦ ) in the octet-singlet basis, we obtain BR Bs → η ν� ¯ ν� = 1.1(1.7) × 10 −6 ,B R(Bs → ημ + μ − ) = 1.5(2.4) × 10 −7 ,B R(Bs → ητ + τ − ) = 3.8(5.8) × 10 −8 ,B R(Bs → η � ν� ¯