Measurement of the average time-integrated mixing probability of b-flavored mesons

Primary authors: Paolo Giromini, Fabio Happacher, Fotios Ptochos

We use a fit to the impact parameters of muon pairs reconstructed in the silicon tracker to estimate the number of like-sign (LS) and opposite-sign (OS) muon pairs arising from double semileptonic decays of b and b hadrons pair-produced at the Fermilab Tevatron collider. The data sample was collected with the upgraded Collider Detector at Fermilab (CDFII) by using a dedicated dimuon trigger. We repeat the measurement on event samples selected with different silicon-track quality requirements and obtain consistent results. The observed ratio of LS to OS dimuons leads to a measurement of the average time-integrated mixing probability of the mixture of b-flavored hadrons which decay semileptonically, χbar= 0.126 ± 0.008, that is consistent with the average LEP value χbar = 0.1259 ± 0.0042.

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