title: Reentrant phenomenon in the quantum phase transitions of a gas of bosons trapped in an optical lattice.
abstract: We calculate the location of the quantum phase transitions of a Bose gas trapped in an optical lattice as a function of effective scattering length a(eff) and temperature T. Knowledge of recent high-loop results on the shift of the critical temperature at weak couplings is used to locate a nose in the phase diagram above the free Bose-Einstein critical temperature T((0))(c), thus predicting the existence of a reentrant transition above T((0))(c), where a condensate should form when increasing a(eff). At zero temperature, the transition to the normal phase produces the experimentally observed Mott insulator.
authors.affiliation: Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Kleinert
authors.forename: S
authors.initials: S
authors.lastname: Schmidt
authors.forename: A
authors.initials: A
authors.lastname: Pelster