The following page shows the result of the first calibration of a Bs flavor tagger on measured data. Essentially it consists of a measurement of the mixing amplitude in four fully reconstructed Bs decay channels. The Same Side Kaon Tagger is hereby used to assess the flavor of the mesons at production time.
The data amount used corresponds to an integrated luminosity of about 5.2 fb-1. The value for the amplitude can now be used to scale the event-by-event dilutions of this tagger. The mean Bs lifetime and the mixing frequency, which are measured at the same time, agree with previous results. The obtained amplitude is used to determine the tagging power of the Same Side Kaon Tagger.
The results were blessed on February 4, 2010. Further information can be found in the public CDF note 10108:
The result on the amplitude is consistent within one standard deviation with the optimal value of 1.0:
A = 0.94 ± 0.15 (stat.) ± 0.13 (syst.)
It is used to calculate a final value for the tagging power. In order to do so, both the systematic and the statistical uncertainty are merged. The result amounts
T = ε A2 D2 = (3.2 ± 1.4 (stat.+syst.) ) %.
The measured physical quantities are in agreement with previous measurements:
cτ = (451.2 ± 5.5 (stat.) ) μm
Δms = (17.79 ± 0.07 (stat.) ) ps-1