Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and weak lensing

We present the first cosmology results from large-scale structure in Dark Energy Survey (DES) spanning 5000 deg$^2$. perform an analysis combining three two-point correlation functions (3$\times$2pt): (i) cosmic shear using 100 million source galaxies, (ii) galaxy clustering, and (iii) cross-correlation of with lens positions. The was designed to mitigate confirmation or observer bias; we describe specific changes made sample following unblinding results. model data within flat $\Lambda$CDM $w$CDM cosmological models. find consistent between functions; their combination yields clustering amplitude $S_8=0.776^{+0.017}_{-0.017}$ matter density $\Omega_{\mathrm{m}} = 0.339^{+0.032}_{-0.031}$ $\Lambda$CDM, mean 68% confidence limits; $S_8=0.775^{+0.026}_{-0.024}$, 0.352^{+0.035}_{-0.041}$, dark energy equation-of-state parameter $w=-0.98^{+0.32}_{-0.20}$ $w$CDM. This DES is prediction favored by Planck 2018 microwave background (CMB) primary anisotropy data, which quantified a probability-to-exceed $p=0.13$ $0.48$. When 3$\times$2pt available baryon acoustic oscillation, redshift-space distortion, type Ia supernovae $p=0.34$. Combining all these sets CMB lensing joint constraints $S_8 0.812^{+0.008}_{-0.008}$, 0.306^{+0.004}_{-0.005}$, $h=0.680^{+0.004}_{-0.003}$, $\sum m_{\nu}<0.13 \;\mathrm{eV\; (95\% \;CL)}$ $\Lambda$CDM; 0.302^{+0.006}_{-0.006}$, $h=0.687^{+0.006}_{-0.007}$, $w=-1.031^{+0.030}_{-0.027}$ (abridged)