Topological susceptibility and η′ meson mass from Nf=2 lattice QCD at the physical point

Abstract

In this paper we explore the computation of topological susceptibility and η′ meson mass in Nf=2 flavor QCD using lattice techniques with a physical value of the pion mass as well as larger pion mass values. We observe that the physical point can be reached without a significant increase in the statistical noise. The mass of the η′ meson can be obtained from both fermionic two point functions and topological charge density correlation functions, giving compatible results. With the pion mass dependence of the η′ mass being flat we arrive at Mη′=772(18) MeV without an explicit continuum limit. For the topological susceptibility we observe a linear dependence on Mπ2, however, with an additional constant stemming from lattice artifacts.