Tetraquark States with Open Flavors

Abstract

In this work, we estimate the masses of tetraquark states with four different flavors by virtue of QCD sum rules, in both $b$ and $c$ sectors. We construct four $[8_c{]}_{\bar{b}s}\otimes [8_c{]}_{\bar{d}u}$ tetraquark currents with $J^P=0^{+}$, and then perform analytic calculation up to dimension eight in the Operator Product Expansion (OPE). We keep terms which are linear in the strange quark mass $m_s$, and in the end find two possible tetraquark states with masses $(5.57\pm 0.15)$ and $(5.58\pm 0.15)$ GeV. We find that their charmed-partner masses lie in $(2.54\pm 0.13)$ and $(2.55\pm 0.13)$ GeV, respectively and are hence accessible in experiments like BESIII and Belle.

Comments: 7 pages, 3 figures