Study of direct CP violation in $B^{\pm }\to J\mathrm{/}\psi K^{\pm }({\pi }^{\pm })$ decays

We present a search for direct CP violation in $B^{\pm} \to J/\psi K^{\pm}(\pi^{\pm})$decays\mathrm{.}Theeventsampleisselectedfrom2.8fb$^{-1}$of$p\bar{p}$ collisions recorded by D0 experiment in Run II of the Fermilab Tevatron Collider. The charge asymmetry $A_{CP}(B^+ \to J/\psi K^+) = +0.0075 \pm 0.0061$(stat\mathrm{.})$\pm 0.0027$(syst.) is obtained using a sample of approximately 40 thousand $B^{\pm }\to J\mathrm{/}\psi K^{\pm }$ 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 $A_{CP}(B^{+}\to J\mathrm{/}\psi {\pi }^{+})=-0.09\pm 0.08$(stat.)$\pm 0.03$(syst.).