Collapse in boson-fermion mixtures of cold atoms trapped in one-dimensional space

We numerically investigated the collapse of one-dimensional boson-fermion mixtures with fermion-boson attractive interactions. With Monte Carlo simulations, we observed spatial distributions of the particles and the behavior of several physical quantities to find the evidence of the collapse. With strong fermion-boson attractions and weak interboson repulsions, almost all the bosons and a part of the fermions were found to gather in a small space. In this collapse process we identified the role of each microscopic parameter such as boson number density, total number densities of the fermions and the bosons, and the interboson repulsion. We show a phase diagram to locate the collapsed phase in the parameter space of the interactions.