Infrared cutoff for dipolar droplets

The beyond mean-field physics due to quantum fluctuations is often described with the Lee-Huang-Yang correction, which can be approximately written as a simple analytical expression in terms of the mean-field wave function employing local density approximation. This model has proven to be very successful in predicting the dynamics in dipolar Bose-Einstein condensates both qualitatively and quantitatively. Yet a small deviation between experimental results and the theoretical prediction has been observed when comparing experiment and theory of the phase boundary of a free-space quantum droplet. For this reason we revisit the theoretical description of quantum fluctuations in dipolar quantum gases. We study alternative cutoffs, compare them to experimental results, and discuss limitations.