First observation of Bs -> phi phi

We have looked for decay of Bs meson in the final state phi phi with the phi decayng to two charged Kaons.  This analysis uses a dataset of approximately 180 pb-1 of data taken with the displaced track trigger of CDFII up to August 2003. Additionally we study the decays Bs-> J/psi phi in the same dataset to be used as a normalization signal for the extraction of the Branching Ratio of Bs->phi phi.
We have found a significant excess of events in the signal region and measure the Branching Ratio:

BR(Bs->phiphi)= (1.4 ± 0.6(stat.) ± 0.2(syst.) ± 0.5(BR's) ) * 10-5

where the last error is due to the uncertainty in the Bs-> J/psi phi Branching Ratio.

This result has been produced for the winter conferences 2004 and have been blessed in the B Physcis Meeting on Thursday Apr 8th, 2004.

A  complete description of the analysis is available here: html, ps.

If you have access to internal CDF documents more details can be found in  cdfnote 6937


Theory Predictions



Blessed Pictures


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Phi->K+K- peak and sideband definition










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phi peak
Sideband and signal region definition
in the MBs-Mphi plane









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sideband definition
Bs->J/psi phi signal in the main trigger









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jpsi phi peak Scenario A
Bs->J/psi phi signal in the prescaled (LOWPT) trigger









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jpsi phi lowpt
Bs->phi phi signal in the main trigger
8 candidates found with 0.75 expected background events










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PhiPhi_ScA
Bs->phi phi signal in the prescaled (LOWPT) trigger
4 candidates found with 1.2 expected background events











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phiphi LOWPT
Bs->phi phi signal in the combined dataset
12 candidates found with 1.95 expected background events










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Phiphi total