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 L₃. Our data follow a L₃=λ₃/T2 law with λ₃=2.5(3) _stat(6)_syst×10^-20 (μK)2 cm6 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 |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.