s-Wave Scattering Resonances Induced by Dipolar Interactions of Polar Molecules

TL;DR

This paper investigates s-wave scattering resonances caused by dipolar interactions in polar molecules, revealing a universal positive effective range that significantly impacts many-body physics, contrasting with Feshbach resonances in cold atoms.

Contribution

It demonstrates that dipolar interactions induce a universal large positive effective range in s-wave resonances, differing fundamentally from Feshbach resonances, and explores the implications for many-body physics and polaron behavior.

Findings

Positive effective range enhances repulsive interactions at high temperature.

At low temperature, polaron binding energy varies across BEC and BCS regimes.

Effects are opposite to those observed in narrow Feshbach resonances.

Abstract

We show that s-wave scattering resonances induced by dipolar interactions in a polar molecular gas have a universal large and positive effective range, which is very different from Feshbach resonances realized in cold atoms before, where the effective range is either negligible or negative. Such a difference has important consequence in many-body physics. At high temperature regime, a positive effective range gives rise to stronger repulsive interaction energy for positive scattering length, and weaker attractive interaction energy for negative scattering length. While at low-temperatures, we study polaron problem formed by single impurity molecule, and we find that the polaron binding energy increases at the BEC side and decreases at the BCS side. All these effects are in opposite to narrow Feshbach resonances where the effective range is negative.