Lattice searches for tetraquarks and mesonic molecules: light scalar mesons and XYZ states

TL;DR

This paper reviews lattice QCD searches for tetraquarks and mesonic molecules, focusing on light scalar mesons and XYZ states, highlighting challenges and methods for identifying exotic states amidst scattering states.

Contribution

It provides a comprehensive review of lattice QCD techniques and results for tetraquarks and mesonic molecules, especially in the light and hidden-charm sectors.

Findings

Identification of scalar resonances sigma, kappa, a0, and f0 as candidates.

Lattice simulations of X(3872), Y(4260), Y(4140), and Z+(4430).

Discussion of methods to distinguish tetraquark/molecular states from scattering states.

Abstract

Searches for tetraquarks and mesonic molecules in lattice QCD are briefly reviewed. In the light quark sector the most serious candidates are the lightest scalar resonances sigma, kappa, a0 and f0. In the hidden-charm sector I discuss lattice simulations of X(3872), Y(4260), Y(4140) and Z^+(4430). The most serious challenge in all these lattice studies is the presence of scattering states in addition to possible tetraquark/molecular states. The available methods for distinguishing both are reviewed and the main conclusions of the simulations are presented.