Fate of the η′ in the quark gluon plasma

In this paper we study the eta' in N-f = 2 + 1 + 1 lattice QCD simulations at finite temperature. Results are obtained from the analysis of the gluonic defined topological charge density correlator after gradient flow. Our results indicate the growth of the eta' mass above the pseudocritical temperature, associated with the chiral symmetry restoration. In the vicinity of the pseudocritical temperature the results are consistent with a small dip in the eta' mass. The magnitude of the dip is compatible with the reduction of the eta' mass obtained by experimental analysis and suggests that eta' mass comes close to zero temperature non-anomalous contribution. (C) 2019 The Authors. Published by Elsevier B.V.