$$ B\to {D}_0^{\ast } $$ and $$ {B}_s\to {D}_{s0}^{\ast } $$ form factors from QCD light-cone sum rules

Abstract

Abstract We present the first application of QCD light-cone sum rules (LCSRs) with B(s)-meson distribution amplitudes to the $$ {B}_{(s)}\to {D}_{(s)0}^{\ast } $$ B s → D s 0 ∗ form factors, where $$ {D}_{(s)0}^{\ast } $$ D s 0 ∗ is a charmed scalar meson. We consider two scenarios for the $$ {D}_0^{\ast } $$ D 0 ∗ spectrum. In the first one, we follow the Particle Data Group and consider a single broad resonance $$ {D}_0^{\ast }(2300) $$ D 0 ∗ 2300 . In the second one, we assume the existence of two scalar resonances, $$ {D}_0^{\ast }(2105) $$ D 0 ∗ 2105 and $$ {D}_0^{\ast }(2451) $$ D 0 ∗ 2451 , as follows from a recent theoretically motivated analysis of B → Dππ decays. The $$ B\to {D}_0^{\ast } $$ B → D 0 ∗ form factors are calculated in both scenarios, also taking into account the large total width of $$ {D}_0^{\ast }(2300) $$ D 0 ∗ 2300 . Furthermore, we calculate the $$ {B}_s\to {D}_{s0}^{\ast } $$ B s → D s 0 ∗ form factors, considering in this case only the one-resonance scenario with Ds0(2317). In this LCSRs calculation, the c-quark mass is kept finite and the s-quark mass is taken into account. We also include contributions of the two- and three-particle distribution amplitudes up to twist-four. Our predictions for semileptonic $$ B\to {D}_0^{\ast}\ell {\nu}_{\ell } $$ B → D 0 ∗ ℓ ν ℓ and $$ {B}_s\to {D}_{s0}^{\ast}\ell {\nu}_{\ell } $$ B s → D s 0 ∗ ℓ ν ℓ branching ratios are compared with the available data and HQET-based predictions. As a byproduct, we also obtain the $$ {D}_0^{\ast } $$ D 0 ∗ - and $$ {D}_{s0}^{\ast } $$ D s 0 ∗ -meson decay constants and predict the lepton flavour universality ratios $$ R\left({D}_0^{\ast}\right) $$ R D 0 ∗ and $$ R\left({D}_{s0}^{\ast}\right) $$ R D s 0 ∗ .