Existence and Non-Existence of Doubly Heavy Tetraquark Bound States

TL;DR

This study uses lattice-QCD to investigate the existence of doubly heavy tetraquark bound states, finding evidence for some configurations but not others, and analyzing their internal structure.

Contribution

It provides the first lattice-QCD evidence for bound doubly heavy tetraquarks with specific quark content, highlighting the importance of operator choices and internal structure analysis.

Findings

Bound states found for $ ar{b}ar{b}ud $ and $ ar{b}ar{b}us $

No binding observed for $ ar{b}ar{c}ud $

Analysis of meson-meson and diquark-antidiquark components

Abstract

In this work we investigate the existence of bound states for doubly heavy tetraquark systems $ \bar{Q}\bar{Q}'qq' $ in a full lattice-QCD computation, where heavy bottom quarks are treated in the framework of non-relativistic QCD. We focus on three systems with quark content $ \bar{b}\bar{b}ud $, $ \bar{b}\bar{b}us $ and $ \bar{b}\bar{c}ud $. We show evidence for the existence of $ \bar{b}\bar{b}ud $ and $ \bar{b}\bar{b}us $ bound states, while no binding appears to be present for $ \bar{b}\bar{c}ud $. For the bound four-quark states we also discuss the importance of various creation operators and give an estimate of the meson-meson and diquark-antidiquark percentages.