Relaxing DESI DR2 BAO Constraints on $\sum m_\nu$ with Planck and SPT-3G 2018 in the Context of SPT D1

Abstract

We present constraints on the sum of neutrino masses $\sum m_\nu$ from a dataset incorporating the full SPT-3G 2018 TT/TE/EE+lensing spectra together with Planck PR4 lensing and low-$\ell$ parts of the Planck PR3 spectra. Using it as a baseline for the DESI DR2 BAO measurements, we arrive at a $95\%$ upper limit of $\sum m_\nu < 0.11$ eV, relaxing the tension between $\rm \Lambda$CDM and lower bounds on $\sum m_\nu$ based on neutrino oscillation experiments. When including DES Y1 weak lensing information and the Pantheon+ SNIa catalog, the limit is further loosened to $\sum m_\nu<0.138$ eV with a slight preference for $\sum m_\nu>0$. On contrast, replacing SPT-3G 2018 primary CMB and lensing spectra with ones from the SPT-3G 2019-2020 (D1) release tightens the overall constraint to $<0.082$ eV and pushes the $\sum m_\nu$ posterior mode value to zero, indicating a preference for quasi-negative neutrino masses in line with the D1 analysis. This is a curious shift within SPT-3G measurements of the same field taken in 2018 and in 2019-2020 and processed with different analysis pipelines.