CP Asymmetry in semileptonic B decays

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:

A_SL = 0.0080 ± 0.0090 (stat) ± 0.0068 (syst)

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 B_s decays:

A^s_SL= 0.020 ± 0.021 (stat) ± 0.016 (syst) ± 0.009 (inputs)

A^s_SL is calculated using our measurement of A_SL, HFAG 2007 world average (f_sZ_s) /(f_dZ_d), and the average value of A^d_SL measured by the B factories.)

Below are the eps versions of figures meant for downloads.

Figure 1: Combined 3D impact parameter distribution (.eps)
Figure 2: &mu⁺&mu^- impact parameter distribution (.eps)
Figure 3: &mu⁺&mu^- fit x-projection (log) and residual (.eps)(.eps)
Figure 4: &mu⁺&mu^- fit y-projection and residual (.eps)(.eps)
Figure 5: &mu⁺&mu⁺ impact parameter distribution (.eps)
Figure 6: &mu⁺&mu⁺ fit x-projection (log) and residual (.eps)(.eps)
Figure 7: &mu⁺&mu⁺ fit y-projection and residual (.eps)(.eps)
Figure 8: &mu^-&mu^- impact parameter distribution (.eps)
Figure 9: &mu^-&mu^- fit x-projection (log) and residual (.eps)(.eps)
Figure 10: &mu^-&mu^- fit y-projection and residual (.eps)(.eps)
Figure 11: &Upsilon dimuon impact parameter distribution (.eps)
Figure 12: &Upsilon mass distribution (.eps)
Figure 13: D⁰ mass distribution (for K⁺) (.eps)
Figure 14: D⁰ mass distribution (for K^-) (.eps)
Figure 15: D⁰ mass distribution (for &pi⁺) (.eps)
Figure 16: D⁰ mass distribution (for &pi^-) (.eps)
Figure 17: D⁰ mass distribution (for K⁺ faking &mu) (.eps)
Figure 18: D⁰ mass distribution (for K^- faking &mu) (.eps)
Figure 19: D⁰ mass distribution (for &pi⁺ faking &mu) (.eps)
Figure 20: D⁰ mass distribution (for &pi^- faking &mu) (.eps)
Figure 21: D^* - D⁰ mass difference (.eps)

ASL = 0.0080 ± 0.0090 (stat) ± 0.0068 (syst)

AsSL= 0.020 ± 0.021 (stat) ± 0.016 (syst) ± 0.009 (inputs)

A_SL = 0.0080 ± 0.0090 (stat) ± 0.0068 (syst)

A^s_SL= 0.020 ± 0.021 (stat) ± 0.016 (syst) ± 0.009 (inputs)