Spectroscopy of tetraquark mesons

Abstract

A classification of tetraquark states in terms of the spin-flavour, colour and spatial degrees of freedom has been constructed. The permutational symmetry properties of both the spin-flavour and orbital parts of the quark-quark and antiquark-antiquark subsystems are briefly discussed. This classification is useful both for model-builders and experimentalists. An evaluation of the tetraquark spectrum is obtained from a Iachello mass formula for tetraquark systems. The ground state tetraquark nonet is identified with $f_0(600)$, $\kappa (800)$, $f_0(980)$, $a_0(980)$. The mass splittings predicted by this mass formula are in agreement with the KLOE, Fermilab E791 and BES experimental data.

Comments: Invited talk at 26th International Colloquia in Group Theoretical Methods in Physics (XXVI ICGTMP), New York City, USA, 26-30 Jun, 2006