Search for Bc+ -> Bs0 pi+, Bs0 -> J/psi phi decays at the CDF II detector

This analysis details the search for Bc+ -> Bs0 pi+, Bs0 -> J/psi phi decays, and the charge conjugate mode, using the CDF II detector at the Fermi National Accelerator Laboratory. The search is derived from a sample of 5.84 fb-1 of data from ppbar collisions of sqrt(s) = 1.96 TeV collected via J/psi trigger paths. Selection of candidate events within the Di-Muon trigger dataset is performed in two stages, both using artificial neural networks trained to select signal over combinatoric backgrounds. A 95% confidence upper limit is set on the number of Bc+ -> Bs0 pi+ events within our sample, n(signal) <= 4.15, for Bs0 candidate events of pT >= 4.0 GeV/c and |eta| <= 1.0. Using this to compute the ratio sigma(Bc -> Bs pi)/sigma(Bs), a 95% confidence limit is set on the quantity f(Bc+)/f(Bs0) * B(Bc+ -> Bs0 pi+) <= 0.00683, where f(Bc+) is the fragmentation fraction of bbar quarks to Bc+ mesons and f(Bs0) is the fragmentation fraction of bbar quarks to Bs0 mesons. Assuming a ratio of fragmentation fractions f(Bc+)/f(Bs0) = 0.014, as estimated from yields in related experiments, a limit is placed on the branching fraction, B(Bc+ -> Bs0 pi+) <= 48.8%.