The Search for Beauty-fully Bound Tetraquarks Using Lattice Non-Relativistic QCD

TL;DR

This study uses lattice non-relativistic QCD to search for a bottomonium-like tetraquark state, finding no evidence of such a bound state below the relevant thresholds.

Contribution

First lattice QCD search for a $ar{b}ar{b}bb$ tetraquark using multiple ensembles and novel potential methods, providing the most comprehensive analysis to date.

Findings

No evidence of a bound tetraquark below the threshold

Used multiple lattice spacings and physical quark masses

Exploratory potential addition to detect near-threshold states

Abstract

Motivated by multiple phenomenological considerations, we perform the first search for the existence of a $\bar{b}\bar{b}bb$ tetraquark bound state with a mass below the lowest non-interacting bottomonium-pair threshold using the first-principles lattice non-relativistic QCD methodology. We use a full $S$-wave colour/spin basis for the $\bar{b}\bar{b}bb$ operators in the three $0^{++}$, $1^{+-}$ and $2^{++}$ channels. We employ four gluon field ensembles at multiple lattice spacing values ranging from $a = 0.06 - 0.12$ fm, all of which include $u$, $d$, $s$ and $c$ quarks in the sea, and one ensemble which has physical light-quark masses. Additionally, we perform novel exploratory work with the objective of highlighting any signal of a near threshold tetraquark, if it existed, by adding an auxiliary potential into the QCD interactions. With our results we find no evidence of a QCD bound tetraquark below the lowest non-interacting thresholds in the channels studied.