  A measurement of the ratio of the branching fractions of the B[0,s] meson to
J/psi f0(980) and to J/psi phi(1020) is presented. The J/psi, f0(980), and
phi(1020) are observed through their decays to mu+ mu-, pi+ pi-, and K+ K-,
respectively. The f0 is identified by requiring abs( M[pi+,pi-] - 974 MeV ) <
50 MeV. The analysis is based on a data sample of pp collisions at a
centre-of-mass energy of 7 TeV, collected by the CMS experiment, corresponding
to an integrated luminosity of 5.3 inverse femtobarns. The measured ratio is
B(B[0,s] to J/psi f0(980)) B(f0 to pi+ pi-) / B(B[0,s] to J/psi phi(1020))
B(phi(1020) to K+ K-) = 0.140 +/- 0.008 +/- 0.023, where the first uncertainty
is statistical and the second is systematic.
