Transition form factors for $D/B$ to $a_{0}(980)$ from light-cone QCD sum rules

Abstract

We apply the light-cone QCD sum rules with chiral currents to compute transition form factors of the semileptonic decay of the charmed and bottom scalar mesons $D/B$ to $a_{0}(980)l^{+}ν_{l}$ $(l=e$, $μ)$, where the scalar meson $a_{0}(980)$ are firstly regarded as two quark states, and contributions from the tetraquark component are then added via proper modulation of four distribution amplitudes considered. The obtained transition form factors and branching fraction are free of the contribution from the light-cone distribution amplitudes at the level of twist-three and two simple relations connecting their form factors are obtained. Our computations indicates that the decay branch fractions are on the margin of the measurements reported by Beijing Spectrometer \uppercase\expandafter{\romannumeral3} in the pure two-quark scenario and are in good agreement with observations when tetraquark component is considered.

Figures (17)

• Figure 1: The distribution amplitudes of the $a_{0}(980)$ obtained by QCD sum rule at $z^{2}=0$ for DA-I.
• Figure 2: The distribution amplitudes of the $a_{0}(980)$ obtained by QCD sum rule at a new approximation for DA-II.
• Figure 3: The distribution amplitudes of the $a_{0}(980)$ obtained by BLFQ for DA-III.
• Figure 4: The distribution amplitudes of the $a_{0}(980)$ obtained from BLFQ for DA-IV.
• Figure 5: The distribution amplitudes of the $a_{0}(980)$ shown with the solid (DA-I), the dash (DA-II), the dot (DA-III) and the dash dot (DA-IV) lines. Two lines corresponding to DA-III and DA-IV overlap exactly.