  We theoretically investigate normal-state properties of an ultracold Fermi
gas with an orbital Feshbach resonance (OFR). Recently, OFR has attracted much
attention as a promising pairing mechanism to realize a superfluid 173Yb Fermi
gas. Including pairing fluctuations within a T-matrix approximation, and
removing effects of an experimentally inaccessible deep bound state, we
evaluate strong-coupling corrections to single-particle excitations. With
increasing the strength of an OFR-induced tunable pairing interaction, the open
channel is shown to exhibit the pseudogap phenomenon in the BCS-BEC crossover
region, as in the case of a broad magnetic Feshbach resonance (MFR) in 6Li and
40K Fermi gases. We also show that the strong pairing interaction affects the
closed channel, leading to the coexistence of particle and hole branches in the
single-particle spectral weight. Since the latter phenomenon cannot be observed
in the conventional MFR case, it may be viewed as a characteristic
strong-coupling phenomenon peculiar to the OFR case.
