Observation of B(s)⁰→J/ψf₀(980) and evidence for B(s)⁰→J/ψf₀(1370)

Predictions for the [Formula: see text] decay

We calculate the shape of the [Formula: see text] and [Formula: see text] invariant mass distributions in the [Formula: see text] and [Formula: see text] decays that are dominated by the [Formula: see text] resonance. The weak interaction part is the same for both processes and the hadronization into the different meson-baryon channels in the final state is given by symmetry arguments. The most important feature is the implementation of the meson-baryon final-state interaction using two chiral unitary models from different theoretical groups. Both approaches give a good description of antikaon-nucleon scattering data, the complex energy shift in kaonic hydrogen and the line shapes of [Formula: see text] in photoproduction, based on the two-pole scenario for the [Formula: see text]. We find that this reaction reflects more the higher mass pole and we make predictions of the line shapes and relative strength of the meson-baryon distributions in the final state.

Use of B→J/ψ f0 decays to discern the qq or tetraquark nature of scalar mesons

We consider the relative decay rates of B(0) and Bs(0) mesons into a J/ψ plus a light scalar meson, either the f0(500) (σ) or the f0(980). We show that it is possible to distinguish between the quark content of the scalars being quark-antiquark or tetraquark by measuring specific ratios of decay rates. Using current data we determine the ratio of form factors in Bs(0)→J/ψf0(980) with respect to B(0)→J/ψf0(500) decays to be 0.99(-0.04)(+0.13) at a four-momentum transfer squared equal to the mass of the J/ψ meson squared. In the case where these light mesons are considered to be quark-antiquark states, we give a determination of the mixing angle between strange and light quark states of less than 29° at 90% confidence level. We also discuss the use of a similar ratio to investigate the structure of other isospin singlet states.

First observation of B(s)(0) → J/ψη and B(s)(0) → J/ψη'

We report first observations of B(s)(0) → J/ψη and B(s)(0) → J/ψη'. The results are obtained from 121.4  fb(-1) of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e+ e- collider. We obtain the branching fractions B(B(s)(0) → J/ψη)=[5.10±0.50(stat)±0.25(syst)(-0.79)(+1.14)(N(B(s)(*) B(s)(*))]×10(-4), and B(B(s)(0) → J/ψη')=[3.71±0.61(stat)±0.18(syst)(-0.57)(+0.83)(N(B(s)(*) B(s)(*))]×10(-4). The ratio of the two branching fractions is measured to be (B(B(s) → J/ψη'))/(B(B(s) → J/ψη))=0.73±0.14(stat)±0.02(syst).