title: Indirect observation of an in-medium η' mass reduction in √s NN =200  GeV Au+Au collisions.
abstract: PHENIX Collaboration and STAR Collaboration data on the intercept parameter of the two-pion Bose-Einstein correlation functions in √ s{NN}=200  GeV Au+Au collisions are analyzed in terms of different models of hadronic multiplicities. To describe this combined PHENIX and STAR data set, an in-medium η' mass reduction of at least 200 MeV is needed, at the 99.9% confidence level in the considered model class. Such a significant η' mass modification may indicate the restoration of the U{A}(1) symmetry in a hot and dense hadronic matter and the return of the 9th "prodigal" Goldstone boson.
authors.affiliation: Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA.
authors.forename: T
authors.initials: T
authors.lastname: Csörgo
authors.forename: R
authors.initials: R
authors.lastname: Vértesi
authors.forename: J
authors.initials: J
authors.lastname: Sziklai