Study of $B\to \pi \mathrm{\ell }{\nu }_{\mathrm{\ell }}$ and $B^{+}\to {\eta }^{(\mathrm{\prime })}{\mathrm{\ell }}^{+}{\nu }_{\mathrm{\ell }}$ decays and determination of $\mathrm{\mid }{V}_{ub}\mathrm{\mid }$

We reassess the $B\to \pi \mathrm{\ell }{\nu }_{\mathrm{\ell }}$ differential branching ratio distribution experimental data released by the BaBar and Belle Collaborations supplemented with all lattice calculations of the $B\to \pi$ form factor shape available up to date obtained by the HPQCD, FNAL/MILC and RBC/UKQCD Collaborations. Our study is based on the method of Pad'{e} approximants, and includes a detailed scrutiny of each individual data set that allow us to obtain $\mathrm{\mid }{V}_{ub}\mathrm{\mid }=3.53(8{)}_{\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}}(6{)}_{\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}}\times {10}^{-3}$. The semileptonic $B^{+}\to {\eta }^{(\mathrm{\prime })}{\mathrm{\ell }}^{+}{\nu }_{\mathrm{\ell }}$ decays are also addressed and the $\eta$-${\eta }^{\mathrm{\prime }}$ mixing discussed.