B → Dℓνℓ form factors beyond leading power and extraction of |Vcb| and R(D)

A bstract We investigate the subleading-power corrections to the exclusive B → Dℓν ℓ form factors at O O ( αₛ⁰ α s 0 ) in the light-cone sum rules (LCSR) framework by including the two- and three-particle higher-twist contributions from the B -meson light-cone distribution amplitudes up to the twist-six accuracy, by taking into account the subleading terms in expanding the hard-collinear charm-quark propagator, and by evaluating the hadronic matrix element of the subleading effective current "Image missing". Employing further the available leading-power results for the semileptonic B → D form factors at the next-to- leading-logarithmic level and combining our improved LCSR predictions with the recent lattice determinations, we then carry out a comprehensive phenomenological analysis on the semi-leptonic B → Dℓν ℓ decay. We extract $$ |{V}cb|=({40.2}-0.5+0.6{|{{}ₜₕ}-1.4+1.4|}ₑₓₚ)× {10}⁻³(|{V}cb|=({40.9}-0.5+0.6{|{{}ₜₕ}-1.0+1.0|}ₑₓₚ)× {10}⁻³) $$ V cb = 40.2 − 0.5 + 0.6 th − 1.4 + 1.4 exp × 10 − 3 V cb = 40.9 − 0.5 + 0.6 th − 1.0 + 1.0 exp × 10 − 3 using the BaBar (Belle) experimental data, and particularly obtain for the gold-plated ratio R ( D ) = 0 . 302 ± 0 . 003.