Alternative to the hyperfine-change-collision interpretation for the behavior of magneto-optical-trap losses at low light intensity

Usually, the large trap loss rates observed in MOTs at the low light intensity regime have been associated with hyperfine change collisions (HCC). We propose an alternative mechanism to explain the sudden raise up of trap loss rates at low intensity without relying on HCC. Using the Gallagher-Pritchard model [Phys. Rev. Lett. 63, 957 (1989)] together with an intensity dependent escape velocity, we were able to reproduce qualitatively well some existing experimental results, including recent observations by Nesnidal et al. [Phys. Rev. A 62, 030701(R) (2000)]. This result reopens the discussion in order to better understand the physical mechanisms and their actual contribution to the trap losses.