We compare flavour singlet and non-singlet vector mesons from first principles using lattice QCD. With N_f=2 flavours of light quark, this addresses the omega-rho mass difference. Using maximally twisted-mass lattice QCD, we are able for the first time to determine this mass difference precisely and we compare with experiment. We also discuss omega-rho mixing effects arising within QCD through the u-d quark mass difference.
@article{arxiv.0902.3897,
title = {The omega-rho meson mass splitting and mixing from lattice QCD},
author = {ETM Collaboration and C. McNeile and C. Michael and C. Urbach},
journal= {arXiv preprint arXiv:0902.3897},
year = {2014}
}