Photoemission spectrum in the BCS–BEC crossover regime of a rare-earth Fermi gas with an orbital Feshbach resonance

We theoretically investigate photoemission spectrum (PES) in a ¹⁷³Yb Fermi gas with a tunable pairing interaction associated with an orbital Feshbach resonance. Including the two-channel character of this rare-earth atomic system, we examine strong-coupling effects on single-particle properties of the open and closed channels, within the framework of an T-matrix approximation in terms of fluctuations in the Cooper channel. In the BCS–BEC crossover region, PES in the closed channel is shown to exhibit non-vanishing intensity in the negative energy region, as an effect of pairing fluctuations. On the other hand, PES in the open channel exhibits a pseudogap phenomenon, as in the case of a broad magnetic Feshbach resonance discussed in ⁴⁰K and ⁶Li Fermi gases. We also examine effects of a harmonic trap in the local density approximation, to see how the spatial inhomogeneity affects strong-coupling corrections to PES. (author)