Electromagnetic form factors of the $B_c$-like tetraquarks: molecular and diquark-antidiquark pictures

Abstract

In this study, we use the molecular and diquark-antidiquark tetraquark pictures to investigate magnetic and quadrupole moments of the $B_c$-like ground state tetraquarks with the QCD light-cone sum rules with quantum numbers $J^P=1^{+}$. In the numerical analysis, to obtain the magnetic and quadrupole moments of $B_c$-like tetraquark states molecular and diquark-antidiquark forms of interpolating currents, and photon distribution amplitudes have been used. The magnetic moments are acquired as ${\mu }_{Z_{uc\bar{u}\bar{b}}}^{Mol}=1.18_{-0.40}^{+0.52}{\mu }_N$, ${\mu }_{Z_{uc\bar{u}\bar{b}}}^{Di}=3.05_{-0.95}^{+1.19}{\mu }_N$, ${\mu }_{Z_{dc\bar{d}\bar{b}}}^{Mol}=0.32_{-0.10}^{+0.18}{\mu }_N$, and ${\mu }_{Z_{dc\bar{d}\bar{b}}}^{Di}=2.38_{-0.75}^{+0.95}{\mu }_N$. The hadrons' magnetic and quadrupole moments are another fundamental observable as their mass, which provides information on the underlying quark structure and dynamics. The results obtained in both pictures are quite different from each other. Any experimental measurement of the magnetic moments can provide an understanding of the internal structure of these states. We get nonzero but small values for the quadrupole moments of $B_c$-like tetraquark states showing non-spherical charge distributions. Hopefully, the examinations given in this study will be helpful to an experimental search of them, which will be an interesting research subject.

Comments: 13 pages, 1 figure and 2 tables; version accepted for publication in Physics Letters B