Study of direct CP violation in $B^pm o J/psi K^pm(pi^pm)$ decays

Abstract

We present a search for direct CP violation in $B^{pm} to J/psi K^{pm}(pi^{pm})$ decays. The event sample is selected from 2.8 fb$^{-1}$ of $pbar{p}$ collisions recorded by D0 experiment in Run II of the Fermilab Tevatron Collider. The charge asymmetry $A_{CP}(B^_s16 to J/psi K^_s16) = _s160.0075 pm 0.0061$(stat.)$pm 0.0027$(syst.) is obtained using a sample of approximately 40 thousand $B^{pm} to J/psi K^{pm}$ decays. The achieved precision is of the same level as the expected deviation predicted by some extensions of the standard model. We also measured the charge asymmetry $A_{CP}(B^_s16 to J/psi pi^_s16) = -0.09 pm 0.08$(stat.)$pm 0.03$(syst.).