Metallicity of the double Red Clump in the Milky Way Bulge

We present a reanalysis of the metallicity of the double red clump (RC) stars from the Milky Way bulge. Two leading explanations for the existence of the double RC concern possible differences in chemical composition (multiple populations of stars) or distance (X-shaped bulge). We aim to verify the chemical composition hypothesis by determining the mean metallicity of each RC. We use infrared photometric data and metallicities from a previous study (that are based on the Michigan/Magellan Fiber System spectra). In contrast with previous studies, we assign stars to RCs or the red giant branch using a Bayesian approach. Our resulting difference between mean metallicity of the two RCs equals: $0.23^{+0.19}_{-0.24}$ or $0.28^{+0.17}_{-0.18}~\mathrm{dex}$, if the red giant branch bump is included or not, respectively. Because of the high statistical error, the result does not confirm the multiple populations hypothesis.