Measurement of the semileptonic charge asymmetry in B0 meson mixing with the D0 detector
We present a measurement of the semileptonic mixing asymmetry for B0 mesons, ad sl, using two independent decay channels: B0 ! þD X, with D ! Kþ ; and B0 ! þD X, with D ! D0 , D0 ! Kþ (and charge conjugate processes). We use a data sample corresponding to 10:4 fb 1 of pp collisions at ffiffiffis p ¼ 1:96 TeV, collected with the D0 experiment at the Fermilab Tevatron collider. We extract the charge asymmetries in these two channels as a function of the visible proper decay length of the B0 meson, correct for detector-related asymmetries using data-driven methods, and account for dilution from charge-symmetric processes using Monte Carlo simulation. The final measurement combines four signal visible proper decay length regions for each channel, yielding ad sl ¼ ½0:68 0:45ðstatÞ 0:14ðsystÞ %. This is the single most precise measurement of this parameter, with uncertainties smaller than the current world average of B factory measurements.