Including heavy spin effects in a lattice QCD study of static-static-light-light tetraquarks

TL;DR

This study extends previous lattice QCD analyses of $ar b ar b u d$ tetraquarks by incorporating heavy spin effects, demonstrating that the predicted bound state remains stable with these effects included.

Contribution

We develop a method to include heavy spin effects in lattice QCD calculations of tetraquarks, showing the persistence of the bound state.

Findings

Heavy spin effects slightly weaken the binding energy.

The $ar b ar b u d$ tetraquark remains bound when heavy spin effects are included.

Binding energy is comparable to previous static approximation results.

Abstract

In previous works we predicted the existence of a $\bar b \bar b u d$ tetraquark with quantum numbers $I(J^P) = 0(1^+)$ using the static approximation for the $\bar b$ quarks and neglecting heavy spin effects. Since the binding energy is of the same order as expected for these heavy spin effects, it is essential to include them in the computation. Here we present a corresponding method and show evidence that binding is only slightly weakened and that the $\bar b \bar b u d$ tetraquark persists.