Competition between final-state and pairing-gap effects in the radio-frequency spectra of ultracold Fermi atoms

TL;DR

This paper investigates the interplay between pairing-gap effects and final-state interactions in the radio-frequency spectra of ultracold Fermi atoms, revealing a complex competition that affects spectral peak positions.

Contribution

It introduces a detailed calculation including final-state interactions and compares results with experimental data, highlighting the competition affecting spectral features.

Findings

Pairing-gap effects push oscillator strength to higher frequencies.

Final-state effects pull oscillator strength toward threshold.

Spectral peak positions are not directly indicative of the pairing gap.

Abstract

The radio-frequency spectra of ultracold Fermi atoms are calculated by including final-state interactions affecting the excited level of the transition, and compared with the experimental data. A competition is revealed between pairing-gap effects which tend to push the oscillator strength toward high frequencies away from threshold, and final-state effects which tend instead to pull the oscillator strength toward threshold. As a result of this competition, the position of the peak of the spectra cannot be simply related to the value of the pairing gap, whose extraction thus requires support from theoretical calculations.