Collaboration, D0 and Bertram, Iain and Borissov, Guennadi and Ross, Anthony and Williams, Mark and Ratoff, Peter and Fox, Harald and Lamont, Iain and Beattie, Michael (2013) An improved measurement of direct CP violation parameters in B^+- -> J/psi K^+- and B^+- -> J/psi pi^+- decays. Physical review letters, 110 (24): 241801. ISSN 1079-7114
Abstract
We present a measurement of the direct CP-violating charge asymmetry in B± mesons decaying to J/ψK± and J/ψπ± where J/ψ decays to μ+μ-, using the full run II data set of 10.4 fb-1 of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. A difference in the yield of B- and B+ mesons in these decays is found by fitting to the difference between their reconstructed invariant mass distributions resulting in asymmetries of AJ/ψK=[0.59±0.37]%, which is the most precise measurement to date, and AJ/ψπ=[-4.2±4.5]%. Both measurements are consistent with standard model predictions.