Semileptonic Decays of Heavy Vector Mesons in Hard-Wall AdS/QCD with $N_{f}=5$

Abstract We present a systematic study of semileptonic decays of heavy vector mesons within the Hard-Wall AdS/QCD framework. Semileptonic decays provide a clean environment for testing the Standard Model because the leptonic current is well understood, while the hadronic part is encoded in transition form factors that reflect non-perturbative QCD dynamics. The processes under consideration include: \( \psi \to D^{*-} ( D^{-} ) \ell^{+} {\nu}_{\ell} \), \( D^{*0} \to \pi^{-} \ell^{+} {\nu}_{\ell} \), \( D^{*+}_{s} \to K^{0} \ell^{+} {\nu}_{\ell} \), \( D^{*0} \to \rho^{-} \ell^{+} {\nu}_{\ell} \), \( B_c^{*+} \to B^{*0} \ell^{+} {\nu}_{\ell} \), \( B_c^{*+} \to \psi \,\ell^{+} {\nu}_{\ell} \), \( B^{*-} \to D^{*0} \ell^{-} \bar{\nu}_{\ell} \), \( B^{*0} \to D^{*+}(D^{+}) \ell^{-} \bar{\nu}_{\ell} \), \( B^{*0}_{s} \to D^{*+}_{s} (D^{+}_{s}) \ell^{-} \bar{\nu}_{\ell} \), \( \psi \to D^{*-}_{s}(D^{-}_{s}) \ell^{+} {\nu}_{\ell} \), \( D^{*0} \to K^{*-} (K^{-}) \ell^{+} {\nu}_{\ell} \), \( B_c^{*-} \to D^{*0} \ell^{-} \bar{\nu}_{\ell} \), \( \bar{B_{s}}^{*0} \to K^{*+} \ell^{-} \bar{\nu}_{\ell} \), and \( \bar{B}^{*0} \to \rho^{+} \ell^{-} \bar{\nu}_{\ell} \). These decays correspond to four different quark-level transitions: \(c\to d\), \(b\to c\), \(c\to s\), and \(b\to u\), allowing us to explore a broad range of flavor dynamics.\\ Using the Hard-Wall AdS/QCD model, we compute the relevant transition form factors as functions of the momentum transfer \(q^{2}\). The framework provides analytic expressions for meson wave functions and decay constants, which serve as inputs for the form-factor calculations. From these form factors, we evaluate the differential and integrated branching ratios for each decay mode. Where possible, we compare our predictions with results obtained from other non-perturbative approaches. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.