Jordi Boronat (UPC, Barcelona)
Finite-range effects in dilute quantum gases

Some recent experimental data of different dilute Bose and Fermi gases have shown effects that go beyond the description of these systems with a purely contact interaction. Up to very recently, all the physics of these dilute gases has been studied with interactions that depend only on the value of the s-wave scattering length. We have introduced in the analysis the effective range, which is is the first energy correction to the s-wave scattering. Using quantum Monte Carlo techniques, we have shown that the universality of the equations of state of these systems can be extended if one considers the effective range in addition to the scattering length. With these data we have built a new density functional for attractive Bose mixtures that can explain some experimental data which did not match with existing theory. Similar effects have been observed in the determination of critical numbers for the stability of dipolar drops and in the two-dimensional Fermi polaron.