2019/05/20 by Ottnad, Konstantin
#FOS: Physical sciences #High Energy Physics - Lattice (hep-lat)
paper · doi:10.48550/arxiv.1905.08385
We investigate the masses and mixing of η, η' mesons in the framework of twisted mass lattice QCD with Nf=2+1+1 dynamical quark flavors. For the first time we perform a controlled chiral and continuum extrapolation to obtain physical results. To this end, we have analyzed 17 gauge ensembles with pion masses ranging from 220 MeV to 500 MeV and at three values of the lattice spacing. This calculation became feasible through the application of a powerful variance reduction technique for the computation of quark-disconnected diagrams together with several improvements in the final analysis, including a correction of the relevant correlation functions for residual topological finite volume effects. We obtain physical results for the masses Mη=557(11)stat(03)χPT MeV and Mη'=911(64)stat(03)χPT MeV, as well as the mixing angle in the quark flavor basis ϕ=38.8(2.2)stat(2.4)χPT^∘, in excellent agreement with other results from phenomenology. Similarly, for the physical values of the decay constant parameters we find fl=125(5)stat(6)χPT MeV and fs=178(4)stat(1)χPT MeV. Finally, we present a test of the Veneziano Witten formula using our lattice data.