SPT-3G D1: CMB temperature and polarization power spectra and cosmology from 2019 and 2020 observations of the SPT-3G Main field

I will present the most precise measurements of CMB temperature and polarization power spectra from SPT-3G observations of 4% of the sky during 2019-2020. Using the deepest CMB maps to date for a TT/TE/EE analysis, we achieve the most precise measurements of the lensed EE and TE spectra at small angular scales. These results provide strong confirmation of the ΛCDM model and yield cosmological constraints comparable to Planck. From SPT-3G alone, we measure H₀=66.66±0.60 km/s/Mpc, confirming the Hubble tension at 6.2σ significance relative to SH0ES. For the first time, combined ground-based CMB experiments (SPT+ACT) reach Planck's constraining power on key parameters—a milestone for CMB cosmology. The combination of all three CMB experiments yields the tightest constraints to date: H₀=67.24±0.35 km/s/Mpc and σ₈=0.8137±0.0038. While CMB data alone show no evidence for physics beyond ΛCDM, we observe a growing 2.8σ discrepancy with DESI BAO results, which drives 2-3σ deviations from the standard model when combined. This work demonstrates the maturity of ground-based CMB experiments and their growing role in precision cosmology.