Lifetime of the Bose Gas with Resonant Interactions

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 L-3. Our data follow a L-3 = lambda(3)/T-2 law with lambda(3) = 2.5(3)(stat)(6)(syst) x 10(-20) (mu K)(2) cm(6) s(-1) 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 vertical bar a vertical bar is smaller than the thermal wavelength. We find that L-3 is continuous across the resonance, and over the whole a < 0 range our data quantitatively agree with our calculation. DOI: 10.1103/PhysRevLett.110.163202