Investigation of the $\eta'$-$\eta_c$-mixing with improved stochastic estimators

Abstract

Charmonia are flavour singlet mesons and thus in principle co ntributions from disconnected quark line diagrams might affect their masses, either directly or via mixing with other flavour singlet channels. We present a first study that takes both effects int o account. We employ improved stochastic all-to-all propagator techniques (including n ew methods) to calculate the diagrams that appear within the mixing matrix between the η ′ and the ηc. The runs are initially performed on Nf = 2 16 3 × 32 configurations with the non-perturbatively improved She ikholeslami-Wilson action, both for valence and sea quarks.