A lattice investigation of exotic tetraquark channels

TL;DR

This lattice study investigates the existence of light-heavy tetraquarks, finding no evidence for deeply-bound states beyond previously identified ones, and refutes some phenomenological models predicting such binding.

Contribution

The paper provides a systematic lattice QCD analysis with improved methods to search for exotic tetraquarks, updating previous results and challenging certain phenomenological predictions.

Findings

No evidence for deeply-bound tetraquarks beyond known states.

Improved lattice techniques reduce systematic uncertainties.

Rules out models predicting significant tetraquark binding in certain channels.

Abstract

We perform an $n_f=2+1$ lattice study of a number of channels where past claims exist in the literature for the existence of strong-interaction-stable light-heavy tetraquarks. We find no evidence for any such deeply-bound states, beyond the $J^P=1^+$, $I=0$ $ud\bar{b}\bar{b}$ and $I=1/2$ $ls\bar{b}\bar{b}$ states already identified in earlier lattice studies. We also describe a number of systematic improvements to our previous lattice studies, including working with larger $m_\pi L$ to better suppress possible finite volume effects, employing extended sinks to better control excited-state contamination, and expanding the number of operators used in the GEVP analyses. Our results also allow us to rule out several phenomenological models which predict significant tetraquark binding in channels where no such binding is found.