Evidence for the existence of $u d \bar{b} \bar{b}$ and the non-existence of $s s \bar{b} \bar{b}$ and $c c \bar{b} \bar{b}$ tetraquarks from lattice QCD

TL;DR

This study uses lattice QCD and quark model techniques to investigate the existence of certain heavy tetraquarks, finding evidence for $udar{b}ar{b}$ states but not for others like $ssar{b}ar{b}$ or $ccar{b}ar{b}$.

Contribution

It provides the first lattice QCD evidence for the existence of $udar{b}ar{b}$ tetraquarks and demonstrates the non-existence of similar states with different quark compositions.

Findings

Evidence supports $udar{b}ar{b}$ tetraquarks in isospin $I=0$.

No evidence found for $ssar{b}ar{b}$ and $ccar{b}ar{b}$ tetraquarks.

Lattice QCD combined with quark model techniques effectively studies heavy tetraquark states.

Abstract

We combine lattice QCD results for the potential of two static antiquarks in the presence of two quarks $q q$ of finite mass and quark model techniques to study possibly existing $q q \bar{b} \bar{b}$ tetraquarks. While there is strong indication for a bound four-quark state for $q q = (ud-du) / \sqrt{2}$, i.e. isospin $I=0$, we find clear evidence against the existence of corresponding tetraquarks with $q q \in \{ uu , (ud+du) / \sqrt{2} , dd \}$, i.e. isospin $I=1$, $q q = s s$ and $q q = c c$.