language: en

[Confidential: not for distribution. Submitted to IOP Publishing for peer review]

21 May 2010

Exclusive rare B s → (K, η, η′ )ℓ ℓ− decays in the light-front quark model

Ho-Meoyng Choi
Department of Physics, Teachers College, Kyungpook National University,
Daegu, Korea 702-701
E-mail: homyoung@knu.ac.kr

Abstract. Using the light-front quark model, we calculate the transition form factors, decay rates, and longitudinal lepton polarization asymmetries for the exclusive rare B s → (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 @BULLET ) in the octet-singlet basis, we obtain BR(B s → η  ν  ¯ ν  ) = 1.1 (1.7) × 10 −6 , BR(B s → ηµ + µ − ) = 1.5 (2.4) × 10 −7 , BR(B s → ητ + τ − ) = 3.8 (5.8) × 10 −8 , BR(B s → η   ν  ¯ ν  ) = 1.8 (1.3) × 10 −6 , BR(B s → η  µ + µ − ) = 2.4 (1.8) × 10 −7 , and BR(B s → η  τ + τ − ) = 3.4 (2.6) × 10 −8 , respectively. The branching ratios for the B s → K(ν  ¯ ν  , , +  − ) decays are at least an order of magnitude smaller than those for the B s → η () (ν  ¯ ν  , , +  − ) decays. The averaged values of the lepton polarization asymmetries for B s → (K, η () ) +  − are obtained as P K L  µ = P η L  µ = P η  L  µ = −0.98, P K L  τ = −0.24, P η L  τ = −0.20 and P η  L  τ = −0.14, respectively.

[Exclusive rare B s → (K, η, η′ )ℓ ℓ− decays in the light-front quark model 2]

1. Introduction