Extracting free-space observables from trapped interacting clusters

Understand

The energy spectrum of two short-range interacting particles in a harmonic potential trap has previously been related to free-space scattering phase shifts.

• But the existing formula for this purpose is exact only in the limit of an infinitely shallow trap.
• Here we provide a systematically improved formula---describing the low-energy dynamics---that enables the use of finite traps.
• This paves the way for extracting nuclear scattering phase shifts from {\it ab initio} nuclear many-body structure calculations, a long-sought goal in nuclear physics.