Structural dissection of hadronic molecules: The D (*)   K– (*) family under QCD light-cone sum rules

Abstract We investigate the static electromagnetic properties of three charm–strange molecular tetraquark candidates with quantum numbers JP = 1+, namely the DK^, D^ K, and D^ K^ systems. The analysis is carried out within the framework of QCD light-cone sum rules, using interpolating currents constructed from colour-singlet meson bilinears to reflect their molecular configurations. Both perturbative and non-perturbative photon contributions are included, and numerical predictions for the magnetic and electric quadrupole moments are obtained. The magnetic moments are found to lie in the range 1–3 nuclear magnetons, with the largest value associated with the D^*K configuration. The quadrupole moments are an order of magnitude smaller, of order 10−3 fm2, indicating only weak deviations from spherical charge distributions. A flavour decomposition shows that the magnetic response is dominated by the light quarks, while the charm-quark contribution is strongly suppressed, a feature naturally expected for loosely bound hadronic molecules. The present analysis extends QCD light-cone sum-rule studies of exotic hadrons by providing a systematic determination of the electromagnetic moments of the D^ () K^ () molecular systems. These results provide quantitative benchmarks and identify several qualitative fingerprints—most notably the vanishing electromagnetic moments of the neutral DK^*, the strong charm-quark suppression, and the smallness of the quadrupole deformations—that, taken together, distinguish the molecular scenario from compact diquark–antidiquark interpretations and may offer useful guidance for future experimental studies of charm–strange exotic states.