Model-independent extraction of form factors and |Vcb | in B ¯ →d l- ν ¯ ? with hadronic tagging at BABAR

Using the entire BABAR Upsilon(4S) dataset, the first two-dimensional unbinned angular analysis of the semileptonic decay B¯→Dl-ν¯? is performed, employing hadronic reconstruction of the tag-side B meson from Upsilon(4S)→BB¯. Here, l denotes the light charged leptons e and μ. A novel data-driven signal-background separation procedure with minimal dependence on simulation is developed. This procedure preserves all multidimensional correlations present in the data. The expected sin2θ_l dependence of the differential decay rate in the Standard Model is demonstrated, where θ_l is the lepton helicity angle. Including input from the latest lattice QCD calculations and previously available experimental data, the underlying form factors are extracted using both model-independent (BGL) and dependent (CLN) methods. Comparisons with lattice calculations show flavor SU(3) symmetry to be a good approximation in the B(s)→D(s) sector. Using the BGL results, the CKM matrix element |Vcb|=(41.09±1.16)×10-3 and the Standard Model prediction of the lepton-flavor universality violation variable R(D)=0.300±0.004, are extracted. The value of |Vcb| from B¯→Dl-ν¯? tends to be higher than that extracted using B¯→D∗l-ν¯?. The Standard Model R(D) calculation is at a 1.97σ tension with the latest HFLAV experimental average.