B → D 0 ∗ $$ B\to {D}_0^{\ast } $$ and B s → D s 0 ∗ $$ {B}_s\to {D}_{s0}^{\ast } $$ 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 → D s 0 ∗ $$ {B}_{(s)}\to {D}_{(s)0}^{\ast } $$ form factors, where D s 0 ∗ $$ {D}_{(s)0}^{\ast } $$ is a charmed scalar meson. We consider two scenarios for the D 0 ∗ $$ {D}_0^{\ast } $$ spectrum. In the first one, we follow the Particle Data Group and consider a single broad resonance D 0 ∗ 2300 $$ {D}_0^{\ast }(2300) $$ . In the second one, we assume the existence of two scalar resonances, D 0 ∗ 2105 $$ {D}_0^{\ast }(2105) $$ and D 0 ∗ 2451 $$ {D}_0^{\ast }(2451) $$ , as follows from a recent theoretically motivated analysis of B → Dππ decays. The B → D 0 ∗ $$ B\to {D}_0^{\ast } $$ form factors are calculated in both scenarios, also taking into account the large total width of D 0 ∗ 2300 $$ {D}_0^{\ast }(2300) $$ . Furthermore, we calculate the B s → D s 0 ∗ $$ {B}_s\to {D}_{s0}^{\ast } $$ form factors, considering in this case only the one-resonance scenario with D s0(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 → D 0 ∗ ℓ ν ℓ $$ B\to {D}_0^{\ast}\ell {\nu}_{\ell } $$ and B s → D s 0 ∗ ℓ ν ℓ $$ {B}_s\to {D}_{s0}^{\ast}\ell {\nu}_{\ell } $$ branching ratios are compared with the available data and HQET-based predictions. As a byproduct, we also obtain the D 0 ∗ $$ {D}_0^{\ast } $$ - and D s 0 ∗ $$ {D}_{s0}^{\ast } $$ -meson decay constants and predict the lepton flavour universality ratios R D 0 ∗ $$ R\left({D}_0^{\ast}\right) $$ and R D s 0 ∗ $$ R\left({D}_{s0}^{\ast}\right) $$ .

Keywords

• Bottom Quarks
• Rare Decays
• Semi-Leptonic Decays