Fate of the η′ in the quark gluon plasma.

In this paper we study the η ′ 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 η ′ 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 η ′ mass. The magnitude of the dip is compatible with the reduction of the η ′ mass obtained by experimental analysis and suggests that η ′ mass comes close to zero temperature non-anomalous contribution. [ABSTRACT FROM AUTHOR]