Electromagnetic properties of the $D_{s1}^{+}(2460)$, $D_{s1}^{+}(2536)$, and their bottom partners in a molecular configuration

Abstract

We investigate the electromagnetic properties of the axial-vector molecular states $D^{\ast }K$, $D{K}^{\ast }$, $B^{\ast }K$, and $B{K}^{\ast }$, which are used to model the charmed states $D_{s1}^{+}(2460)$, $D_{s1}^{+}(2536)$, and their bottom partners with quantum numbers $J^P=1^{+}$. To our knowledge, this presents the first comprehensive calculation of the magnetic and quadrupole moments for these specific molecular configurations. Employing the QCD light-cone sum rule method with molecular-type interpolating currents, we compute these moments and perform a detailed flavor decomposition to reveal the internal distribution of the electromagnetic charge and spin. Our results demonstrate that the light up and down quarks dominate the electromagnetic response, with negligible contributions from the heavy quarks. The $D^{\ast }K$ and $B^{\ast }K$ states exhibit negative quadrupole moments and slightly oblate charge distributions, whereas the $D{K}^{\ast }$ and $B{K}^{\ast }$ states possess positive quadrupole moments and prolate distributions, with significant contributions from the strange quark. The predicted moments provide benchmarks for lattice QCD calculations and are testable through their influence on radiative transitions and photo- and electro-production observables at high-luminosity facilities, offering crucial insights into the internal structure and nature of these axial-vector states.

Comments: 16 pages, 2 tables, 3 figures; version to appear in PRD