Probing the Electromagnetic Structure of Heavy-Light Hybrid Mesons with Vector and Axial-Vector Quantum Numbers

Abstract

We investigate the electromagnetic (EM) properties of vector and axial-vector heavy-light hybrid mesons within the light cone QCD sum rules framework. These states are characterized by an explicit gluonic degree of freedom and are studied through interpolating currents corresponding to the $J^{P(C)}=1^{-(-)}$, $1^{+(-)}$, $1^{+(+)}$, and $1^{-(+)}$ hybrid configurations. By analyzing the correlation function in the presence of an external background photon and matching its hadronic and QCD representations, we derive the light cone sum rules for the magnetic dipole and electric quadrupole form factors and extract the corresponding electromagnetic moments at $Q^2=0$. The QCD side of the sum rules incorporates the perturbative photon emission contributions as well as the relevant non-perturbative effects described by photon distribution amplitudes (DAs). Numerical predictions are obtained for the charged $\bar b g u$, $b g\bar u$, $\bar c g d$, $c g\bar d$, $\bar c g s$, and $c g\bar s$ hybrid configurations. The calculated electromagnetic moments show variations among the different hybrid configurations. A more systematic pattern is observed for the electric quadrupole moments (EQMs): the results obtained from the $\mathcal J_\mu^1$ and $\mathcal J_\mu^3$ currents are generally close to each other, as are those obtained from $\mathcal J_\mu^2$ and $\mathcal J_\mu^4$, with the former pair generally yielding somewhat larger magnitudes. The magnetic dipole moments (MDMs), in contrast, do not necessarily exhibit the same systematic grouping, although they also show variations among the different currents and configurations. For the bottom-containing states...