# The eta and eta' mesons in QCD

Collaboration, UKQCD, McNeile, C and Michael, C
The eta and eta' mesons in QCD. Phys.Lett.B, 491. 123 - 129.

We study the flavour singlet pseudoscalar mesons from first principles using lattice QCD. We explore the quark content of the $\eta$ and $\eta'$ mesons and we discuss their decay constants.