CP Asymmetry in semileptonic B decays

This web page summarizes the results for the measurement of CP asymmetry for same-sign dimuons from B decays with 1.6 fb-1 of data. Corrections to the raw asymmetry are made for contributions from the detector, trigger, and hadrons from B decays which are reconstructed as muons.
The results have been approved as of October 18, 2007.

A summary of this analysis and results can be found in this public note.


Using a dedicated dimuon trigger, we isolate a sample of 660k opposite sign and 440k same sign dimuon pairs. We use impact parameter information of the two muons to separate the b-bbar component of the sample from components arising from prompt and charm sources. After extracting the b-bbar fraction, we correct for hadrons faking muons as well as detector and trigger asymmetries.

We measure:

Under the assumption that the CP asymmetry in charged B and b-baryon decays is negligible, we then correct for the measured semileptonic CP asymmetry in B0 decays (as measured at Babar and Belle) and extract the CP asymmetry for semileptonic Bs decays:

AsSL is calculated using our measurement of ASL, HFAG 2007 world average (fsZs) /(fdZd), and the average value of AdSL measured by the B factories.)

Below are the eps versions of figures meant for downloads.