An improved calculation of the $D_{(s)}^*D_{(s)}V$ and $B_{(s)}^*B_{(s)}V$ couplings from light-cone sum rules

Abstract

We present an improved calculation of the $D_{(s)}^*D_{(s)}V$ and $B_{(s)}^*B_{(s)}V$ coupling constants, where $V$ denotes $\rho$, $K^\ast$, $\omega$, and $\phi$ meson. These couplings govern the QCD long-distance dynamics in interactions between heavy pseudoscalar/vector mesons and light vector mesons. Our analysis is conducted within the framework of QCD light-cone sum rules (LCSRs) by utilizing the light-cone distribution amplitudes (LCDAs) of light vector mesons. By systematically incorporating the subleading power corrections and higher-twist contributions at leading order (LO) and including the next-to-leading order (NLO) corrections at leading power, we achieve enhanced accuracy in the light-cone operator product expansion (OPE) for the underlying correlation function. In assessing the reliability of the established LCSRs, we consider uncertainties arising from the choice of the quark-hadron duality region in the double dispersion relation. Building upon these improvements, we accomplish an optimized computation and analysis for the strong coupling constants $g_{H^\ast HV}$ which are used to extract the effective coupling $\lambda$ in the heavy meson chiral perturbation theory (HM$\chi$PT). Furthermore, we investigate the $SU(3)$ flavour symmetry breaking effects in detail and compare our sum rule calculations with previous studies in an exploratory way.