title: Effects of interactions on the critical temperature of a trapped Bose gas.
abstract: We perform high-precision measurements of the condensation temperature of a harmonically trapped atomic Bose gas with widely tunable interactions. For weak interactions we observe a negative shift of the critical temperature in excellent agreement with mean-field theory. However for sufficiently strong interactions we clearly observe an additional positive shift, characteristic of beyond-mean-field critical correlations. We also discuss nonequilibrium effects on the apparent critical temperature for both very weak and very strong interactions.
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Smith
authors.forename: Robert L D
authors.initials: RL
authors.lastname: Campbell
authors.forename: Naaman
authors.initials: N
authors.lastname: Tammuz
authors.forename: Zoran
authors.initials: Z
authors.lastname: Hadzibabic