Doubly heavy tetraquarks: Heavy quark bindings and chromomagnetically mixings

Abstract

We introduce an enhanced binding energy ${B}_{QQ}$ between heavy-heavy quarks $QQ$ and a flux-tube correction into the chromomagnetic interaction model to study nonstrange doubly heavy tetraquarks ${T}_{QQ}$ ($Q=c,b$). A simple relation in terms of baryon masses is proposed to estimate the binding energies ${B}_{QQ}$ and thereby map the flux-tube corrections in doubly heavy tetraquarks ${T}_{cc}$, ${T}_{bb}$, and ${T}_{bc}$. Our computation via diagonalization of chromomagnetic interaction predicts the doubly charmed tetraquark ${T}_{cc}$ (in color ${\overline{3}}_{c}\ensuremath{\bigotimes}{3}_{c}$) and ${T}_{cc}^{*}$ (in ${6}_{c}\ensuremath{\bigotimes}{\overline{6}}_{c}$) with $I{J}^{P}=0{1}^{+}$ to have masses of 3879.2 and 4287.6 MeV, respectively, with the former being in consistent with the measured mass $3874.7\ifmmode\pm\else\textpm\fi{}0.05\text{ }\text{ }\mathrm{MeV}$ of the doubly charmed tetraquark ${T}_{cc}({1}^{+})=cc\overline{u}\overline{d}$ discovered by LHCb. Further mass predictions are given of the doubly bottom tetraquarks ${T}_{bb}$ and the bottom-charmed tetraquarks ${T}_{bc}$ with ${J}^{P}={0}^{+},{1}^{+},{2}^{+}$, and $I=0$, 1. A chromomagnetic mixing between the color configurations ${\overline{3}}_{c}\ensuremath{\bigotimes}{3}_{c}$ and ${6}_{c}\ensuremath{\bigotimes}{\overline{6}}_{c}$ is noted for the bottom-charmed states ${T}_{bc}$ with $I{J}^{P}=0{1}^{+}$ and $I{J}^{P}=1({0}^{+},{1}^{+})$.

Topics & Concepts