title: η and η' mesons from lattice QCD.
abstract: The large mass of the ninth pseudoscalar meson, the η', is believed to arise from the combined effects of the axial anomaly and the gauge field topology present in QCD. We report a realistic, 2+1-flavor, lattice QCD calculation of the η and η' masses and mixing which confirms this picture. The physical eigenstates show small octet-singlet mixing with a mixing angle of θ=-14.1(2.8)°. Extrapolation to the physical light quark mass gives, with statistical errors only, mη=573(6) MeV and mη'=947(142) MeV, consistent with the experimental values of 548 and 958 MeV.
authors.affiliation: Physics Department, Columbia University, New York, New York 10027, USA.
authors.forename: N H
authors.initials: NH
authors.lastname: Christ
authors.forename: C
authors.initials: C
authors.lastname: Dawson
authors.forename: T
authors.initials: T
authors.lastname: Izubuchi
authors.forename: C
authors.initials: C
authors.lastname: Jung
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: R D
authors.initials: RD
authors.lastname: Mawhinney
authors.forename: C T
authors.initials: CT
authors.lastname: Sachrajda
authors.forename: A
authors.initials: A
authors.lastname: Soni
authors.forename: R
authors.initials: R
authors.lastname: Zhou