Paper detail

Measurement of the B->Xsl+l- branching fraction and search for direct CP violation from a sum of exclusive final states

We present a measurement of the total branching fraction of the flavor-changing neutral-current process B->Xsl+l-, along with partial branching fractions in bins of dilepton and hadronic system (Xs) mass, using a sample of 471x10^6 Upsilon(4S)->BBbar events recorded with the BaBar detector at the PEP-II e+e- collider. B mesons are reconstructed by combining a dilepton pair, either e+e- or mu+mu-, with 10 different Xs final states containing exactly one charged or neutral kaon, two or fewer charged pions, and at most one pi0. Using a sum over these exclusive modes as the basis for extrapolation to the fully inclusive rate, we measure a lepton-flavor-averaged inclusive branching fraction BF(B->Xsl+l-) = (6.73 +0.70-0.64[stat] +0.34-0.25[exp syst] +/- 0.50[model syst])x10^-6 for m(l+l-)^2>0.1 GeV^2/c^4. Restricting our analysis exclusively to final states from which a decaying B meson's flavor can be inferred, we additionally report measurements of the direct CP asymmetry ACP in bins of dilepton mass; over the full dilepton mass range, we find ACP=0.04 +/- 0.11 +/- 0.01$ for a lepton-flavor-averaged sample.