Unitarity constraints and the dispersive matrix

We present updated estimates of | V_cb| and R(D^(*)) based on all the available theoretical and experimental data on semileptonic B → D^(*)ℓν_ℓ decays. These values have been obtained by using the Dispersive Matrix method to describe the hadronic form factors. By analysing all the lattice data we get the theoretical values R^ th(D) = 0.296 ± 0.008 and R^ th(D^*) = 0.262 ± 0.009, which are consistent with the corresponding HFLAV averages at the ≃ 2.0 σ and the ≃ 1.5 σ level, respectively. Moreover, from a bin-per-bin study of the experimental data we obtain the values | V_cb| = (41.0 ± 1.2) ·10^-3 from B → D decay and | V_cb| = (39.92 ± 0.64) ·10^-3 from B → D^* one, whose differences with the latest inclusive determinations never exceed the ≃ 2.5 σ level.