Recently, several studies reported a significant discrepancy between the clustering and lensing of the Baryon Oscillation Spectroscopic Survey (BOSS) galaxies in the $\textit{ Planck}$ cosmology. We construct a simple yet powerful model based on the linear theory to assess whether this discrepancy points toward deviations from $\textit{ Planck}$. Focusing on scales $10<R<30$ $h^{ -1}\mathrm{ Mpc}$, we model the amplitudes of clustering and lensing of BOSS LOWZ galaxies using three parameters: galaxy bias $b_\mathrm{ g}$, galaxy-matter cross-correlation coefficient $r_\mathrm{ gm}$, and $A$, defined as the ratio between the true and $\textit{ Planck}$ values of $\sigma_8$. Using the cross-correlation matrix as a diagnostic, we detect systematic uncertainties that drive spurious correlations among the low-mass galaxies. After building a clean LOWZ sample with $r_\mathrm{ gm}\sim1$, we derive a joint constraint of $b_\mathrm{ g}$ and $A$ from clustering+lensing, yielding $b_\mathrm{ g}=2.47_{ -0.30}^{ +0.36}$ and $A=0.81_{ -0.09}^{ +0.10}$, i.e., a $2\sigma$ tension with $\textit{ Planck}$. However, due to the strong degeneracy between $b_\mathrm{ g}$ and $A$, systematic uncertainties in $b_\mathrm{ g}$ could masquerade as a tension with $A=1$. To ascertain this possibility, we develop a new method to measure $b_\mathrm{ g}$ from the cluster-galaxy cross-correlation and cluster weak lensing using an overlapping cluster sample. By applying the independent bias measurement ($b_\mathrm{ g}=1.76\pm0.22$) as a prior, we successfully break the degeneracy and derive stringent constraints of $b_\mathrm{ g}=2.02_{ -0.15}^{ +0.16}$ and $A=0.96\pm0.07$. Therefore, our result suggests that the large-scale clustering and lensing of LOWZ galaxies are consistent with $\textit{ Planck}$, while the different bias estimates may be related to some observational systematics in the target selection.
Categories: astro-ph.CO