Lattice studies of charmonia and exotics

TL;DR

This paper reviews lattice QCD studies of charmonia and exotics, highlighting recent simulations of resonances, decay effects, and evidence for exotic states like X(3872) and Zc(3900).

Contribution

It presents the first exploratory lattice simulation of charmonium resonances above open charm threshold including decay effects.

Findings

Evidence for X(3872) and its Fock components

Zc(3900) emerging from coupled channel effects

Indication of a pentaquark bound state eta_c N

Abstract

The lattice QCD simulations of charmonia and exotic charmonium-like states are reviewed. I report on the first exploratory simulation of charmonium resonances above open charm threshold which takes into account the strong decay. The puzzles related to the first-excited scalar charmonia are discussed. Evidence for X(3872) is presented along with investigation of its Fock components. The $Z_c^+(3900)$ seems to emerge from the HALQCD approach as a result of the coupled channel effect $J/\psi \pi -D\bar D^*$. The indication for the pentaquark bound state $\eta_c N$ is presented.