Measurement of the \(B^0_s \to J/\psi\phi \) branching fraction at CDF

We present a measurement of the branching fraction of the decay \(B^0_s \to J/\psi\phi\) with the Collider Detector at Fermilab. Using a data sample corresponding to an integrated luminosity of \(10\,\mathrm{fb}^{-1}\) of \(p\bar{p}\) collisions at \(\sqrt{s}=1.96\,\mathrm{TeV}\), we utilize a low transverse momentum dimuon trigger to acquire a large sample of \(J/\psi\to\mu^+\mu^-\) decays. We form fully reconstructed \(B^0_s \to J/\psi\phi\) and \(B^0\to J/\psi K^{\ast}\) candidates using information from the central tracking system and determine the branching fraction of \(B^0_s \to J/\psi\phi\) by normalizing with the \(B^0\to J/\psi K^{\ast}\) decay. The measurement improves the current world average value and can be used to extract information about the ratio of fragmentation fractions \(f_s/f_d\) between \(B^0_s\) and \(B^0\) production rates.