Lifetime of a Bose gas with resonant interactions

B. S. Rem, A. T. Grier, I. Ferrier-Barbut, U. Eismann, T. Langen, N. Navon, L. Khaykovich, F. Werner, D. S. Petrov, F. Chevy, and C. Salomon

Accepted Wednesday Mar 13, 2013

We study the lifetime of a Bose gas at and around unitarity using a Feshbach resonance in lithium 7. At unitarity, we measure the temperature dependence of the three-body decay coefficient L3. Our data follow a L3 = l3 / T2 law with l3 = \lambdafull and are in good agreement with our analytical result based on zero-range theory. Varying the scattering length a at fixed temperature, we investigate the crossover between the finite-temperature unitary region and the previously studied regime where |a| is smaller than the thermal wavelength. We find that L3 is continuous across the resonance, and over the whole a  <  0 range our data quantitatively agree with our calculation.