Measurement of the $CP$ Asymmetry in Semileptonic $B$~Decays at CDF

We present a high-precision measurement of the inclusive $CP$ asymmetry in same sign dimuon events originating from two semileptonic $B$~hadron decays. Using a sample of 1.2~fb$^{-1}$ of $p\bar{p}$ collisions at $\sqrt{s}$=1.96~TeV collected by the Collider Detector at Fermilab, we select events with two identified muons. To isolate the $b\bar{b}$ signal from background sources, we take advantage of the long $B$~lifetime utilizing the impact parameters of the two muons. We correct for charge asymmetries introduced by the detector and other physics effects to extract the $CP$~asymmetry.