Measurement of Bs &rarr &Phi &Phi Branching Ratio with 2.9 fb-1 data
This web page summarizes the results of the ratio of the BR(Bs0 &rarr &Phi &Phi) to the BR(Bs0 &rarr J/&psi &Phi). The measurement is done in 2.9 fb-1 of Two Track Trigger data.
The results have been approved by B Group Meeting as of June 18, 2009.
The analysis
The measurement consists in the evaluation of this ratio:
where:
- N&Phi &Phi: number of Bs &rarr &Phi &Phi events from data;
- NJ/&psi &Phi: number of Bs &rarr J/&psi &Phi events from data;
- &epsilon(Bs &rarr &Phi &Phi): efficiency of Bs &rarr &Phi &Phi evaluated with Monte Carlo;
- &epsilon(Bs &rarr J/&psi &Phi): efficiency of Bs &rarr J/&psi &Phi evaluated with Monte Carlo;
- &epsilon&mu: muon efficiency evaluated with data and Monte Carlo.
The optimized cuts for the two signals are summarized in the following table:
The signal yields are shown in the figures:
The final result of the ratio is:
from which, using the Branching Ratio of Bs &rarr J/&psi &Phi *, modified according
to the updated measurements of the ratio of production cross section of Bs and Bd
mesons, we have:
BR(Bs &rarr &Phi &Phi) = [24.0 ± 2.1(stat) ± 2.7(syst) ± 8.2(BR)] 10 &minus 6
where the last error is due to the uncertainty in the Bs &rarr J/&psi &Phi Branching Ratio.
* Particle Data Group; Phys. Lett. B667,1 (2008)
The blessed figures are:
Theory Prediction reproduced from LHCb public note
- B. Souza de Paula, Y. Xie; LHCb's sensitivity to New CP Violating Phases in the decay Bs &rarr &Phi &Phi, LHCb public Note.
