CP asymmetry measurements in J/ ψK0 and the CKM paradigm

Abstract

Recent experimental observations of CP asymmetry in B→J/ψ +K 0 constitute the first significant signal of CP-violation outside the neutral kaon system; thus they represent an important milestone to test the CKM paradigm. We, therefore, undertake a critical appraisal of the existing experimental and theoretical inputs used to deduce constraints on sin2 β and other important parameters and thus find, in particular, sin2 β>0.47 at 95% CL which is completely compatible with the combined experimental result: sin2 β=0.48±0.16, representing an important success of the CKM model of CP-violation. Searches for new physics in B decays to J/ψ +K 0 like final states will require improved precision; we make some suggestions to facilitate these. We also present a global fit including the new CP asymmetry measurements in B→J/ψ +K 0 as an additional input yielding, e.g., γ=(29°→67°), η ̄ =(0.20→0.37) , ρ ̄ =(0.08→0.36) , J CP=(1.8→3.1)×10 −5, Br(K +→π +ν ν ̄ )=(0.52→0.92)×10 −10 , Br(K L→π 0ν ν ̄ )=(0.11→0.31)×10 −10 and Δm B s =(15.2–28.3) ps −1, all at 95% CL.