$T_{cc}$ and Hidden Charm Tetraquarks $1^+$ and $0^+$in QCD sum rules and Heavy-Quark Spin Symmetry

Abstract

In this work, $T_{cc}$ double charm tetraquark and $1^{+}$ and $0^{+}$ hidden charm tetraquarks are studied within the QCD sum rules framework. In the heavy-quark limit, the $1^+$ and $0^+$ tetraquarks are degenerate and the difference in their masses is an $1/m_c$ effect. It is shown that, although the uncertainty in the mass predictions of each of these hadrons is ${\cal O}(100\;\mathrm{MeV})$, when the mass differences are studied, the uncertainty is reduced to less than ${\cal O}(10\;\mathrm{MeV})$. Hence, it is concluded that if one of the exotic hadrons is observed and its mass is used as input, the masses of the other hadrons can be determined with a precision of ${\cal O}(10\;\mathrm{MeV})$ using the QCD sum rules method.