$D \bar D_1(2420)$ and $D^* \bar D^*(2400)$ molecular states: Probing their electromagnetic fingerprints

Abstract

As in previous decades, a comprehensive understanding of the intricate internal configuration of hadrons continues to be a central objective within both experimental and theoretical hadron physics. This pursuit plays a pivotal role in advancing our knowledge of QCD and critically evaluating the robustness and accuracy of the theoretical models developed to date. Furthermore, deciphering the underlying mechanisms of exotic states, both those currently observed and those anticipated in future experiments, remains a pressing and unresolved challenge. Motivated by this, in the present study, we investigate the electromagnetic properties of the $D \bar D_1(2420)$ and $D^* \bar D^*(2400)$ molecular tetraquark states with quantum numbers $J^{PC} = 1^{--}$, using the QCD light-cone sum rule method. These states are analyzed within a hadronic molecular framework, where their magnetic and quadrupole moments are computed to probe internal structure and geometric deformation. Our results reveal distinct electromagnetic signatures, with the magnetic moments primarily dominated by light-quark contributions, and the quadrupole moments suggesting an oblate charge distribution. The findings are compared with prior studies assuming compact tetraquark configurations, emphasizing the sensitivity of electromagnetic observables to the underlying hadronic structure. This analysis provides critical insights into the nature of exotic hadrons and contributes to the broader understanding of QCD dynamics in the non-perturbative regime.