FIG. . A comparison between the L-PLDM simulated linear spectra (red solid lines) with the analytic expression in Eq. 58 (black dotted lines), for the same model system presented in Fig. . The coupling strength gc ≈ 456 cm -1 is fixed, whereas the cavity loss rate Γ varies. The analytic curve in Eq. 58 is obtained with peaks from the real part of Eq. 57 and Lorentzian broadening of the width given by the imaginary part of Eq. 57.