Measurement of B_{s} &rarr &Phi &Phi Branching Ratio with 2.9 fb^{1} data
Primary authors: Benedetto di Ruzza, Mirco Dorigo, Lorenzo Ortolan,
Marco Rescigno, Anna Maria Zanetti, Giacomo Artoni
This web page summarizes the results of the ratio of the BR(B_{s}^{0} &rarr &Phi &Phi) to the BR(B_{s}^{0} &rarr J/&psi &Phi). The measurement is done with 2.9 fb^{1} of Two Track Trigger data.
The results have been approved by B Group Meeting as of June 19, 2009.
A more detailed description of the results can be found:
 Cdf Public Note 10064 here
The analysis
The measurement consists in the evaluation of this ratio:
where:
 N_{&Phi &Phi}: number of B_{s} &rarr &Phi &Phi events;
 N_{J/&psi &Phi}: number of B_{s} &rarr J/&psi &Phi events;
 &epsilon_{(Bs &rarr &Phi &Phi)}: efficiency of B_{s} &rarr &Phi &Phi evaluated with Monte Carlo;
 &epsilon_{(Bs &rarr J/&psi &Phi)}: efficiency of B_{s} &rarr J/&psi &Phi evaluated with Monte Carlo;
 &epsilon_{&mu}: muon efficiency.
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 B_{s} &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(B_{s} &rarr &Phi &Phi) = [2.40 ± 0.21(stat) ± 0.27(syst) ± 0.82(BR)] 10 ^{ &minus 5}
where the last error is due to the uncertainty in the B_{s} &rarr J/&psi &Phi Branching Ratio.
The blessed figures are:
 KKKK invariant mass after reconstruction and trigger confirmation only .eps .gif

 Sideband subtracted signal, Monte Carlo simulation and B_{s} mass sidebands for the following observables:
 fit vertex &Chi^{2}_{xy} in the plane transverse to the beam. .eps .gif
 L_{xy}, transverse decay length of B_{s} candidates. .eps .gif
 d0, Reconstructed impact parameter with respect the primary vertex of B_{s} candidates. .eps .gif

 d0^{&Phimax}, reconstructed impact parameter for the highest momentum &Phi . .eps .gif

 P_{T}^{Kmin}, minimum transverse momentum among the 4 kaons in the B_{s} candidates decays. .eps .gif
 d0^{&Phimin}, reconstructed impact parameter for the lowest momentum &Phi . .eps .gif

 B_{s} &rarr &Phi &Phi signal yield .jpg .eps .pdf
 B_{s} &rarr J/&psi &Phi signal yield .jpg .eps .pdf
 B_{s} &rarr J/&psi &Phi signal yield exclusively triggered by dispaced track trigger. .jpg .eps .pdf
 CMX muon efficiency .jpg .eps .pdf
 CMP muon efficiency .jpg .eps .pdf
 Invariant Mass for the highest momentum K^{+}K^{} pairs for B_{s} &arr &Phi &Phi candidates. .eps .gif
 Invariant Mass for the lowest momentum K^{+}K^{} pairs for B_{s} &arr &Phi &Phi candidates. .eps .gif
 Sideband subtracted K^{+}K^{} pair mass (two entries for candidates). .eps .gif
Theory Prediction
 B. Souza de Paula, Y. Xie; LHCb's sensitivity to New CP Violating Phases in the decay B_{s} &rarr &Phi &Phi, LHCb public Note.