η and η' mesons from Nf = 2 + 1 + 1 twisted mass lattice QCD

Abstract

We determine mass and mixing angles of η and η' states using N f = 2 + 1 + 1 Wilson twisted mass lattice QCD. We describe how those flavour singlet states need to be treated in this lattice formulation. Results are presented for three values of the lattice spacing, a = 0.061 fm, a = 0.078 fm and a = 0.086 fm, with light quark masses corresponding to values of the charged pion mass in a range of 230 to 500 MeV and fixed bare strange and charm quark mass values. We obtain Mη = 557(15) (45) MeV (first error statistical, second systematic) and ø = 44(5)° for a single mixing angle in the quark flavour basis, θ = -10(5)° in the octet-singlet basis. © SISSA 2012.