{"work":{"id":"9b1a8da3-efa1-4520-92c8-ce85dcf68cfa","openalex_id":null,"doi":null,"arxiv_id":"2503.14744","raw_key":null,"title":"Constraints on Neutrino Physics from DESI DR2 BAO and DR1 Full Shape","authors":null,"authors_text":"W. Elbers, A. Aviles, H. E. Noriega, D. Chebat, A. Menegas, C. S. Frenk","year":2025,"venue":"astro-ph.CO","abstract":"The Dark Energy Spectroscopic Instrument (DESI) Collaboration has obtained robust measurements of baryon acoustic oscillations (BAO) in the redshift range, $0.1 < z < 4.2$, based on the Lyman-$\\alpha$ forest and galaxies from Data Release 2 (DR2). We combine these measurements with external cosmic microwave background (CMB) data from Planck and ACT to place our tightest constraints yet on the sum of neutrino masses. Assuming the cosmological $\\Lambda$CDM model and three degenerate neutrino states, we find $\\sum m_\\nu<0.0642$ eV (95%) with a marginalized error of $\\sigma(\\sum m_\\nu)=0.020$ eV. We also constrain the effective number of neutrino species, finding $N_\\rm{eff} = 3.23^{+0.35}_{-0.34}$ (95%), in line with the Standard Model prediction. When accounting for neutrino oscillation constraints, we find a preference for the normal mass ordering and an upper limit on the lightest neutrino mass of $m_l < 0.023$ eV (95%). However, we determine using frequentist and Bayesian methods that our constraints are in tension with the lower limits derived from neutrino oscillations. Correcting for the physical boundary at zero mass, we report a 95% Feldman-Cousins upper limit of $\\sum m_\\nu<0.053$ eV, breaching the lower limit from neutrino oscillations. Considering a more general Bayesian analysis with an effective cosmological neutrino mass parameter, $\\sum m_{\\nu,\\rm{eff}}$, that allows for negative energy densities and removes unsatisfactory prior weight effects, we derive constraints that are in $3\\sigma$ tension with the same oscillation limit. In the absence of unknown systematics, this finding could be interpreted as a hint of new physics not necessarily related to neutrinos. The preference of DESI and CMB data for an evolving dark energy model offers one possible solution. In the $w_0w_a$CDM model, we find $\\sum m_\\nu<0.163$ eV (95%), relaxing the neutrino tension. [Abridged]","external_url":"https://arxiv.org/abs/2503.14744","cited_by_count":null,"metadata_source":"pith","metadata_fetched_at":"2026-05-21T12:35:07.851609+00:00","pith_arxiv_id":"2503.14744","created_at":"2026-05-08T18:18:54.572446+00:00","updated_at":"2026-05-21T12:35:07.851609+00:00","title_quality_ok":true,"display_title":"Constraints on Neutrino Physics from DESI DR2 BAO and DR1 Full Shape","render_title":"Constraints on Neutrino Physics from DESI DR2 BAO and DR1 Full Shape"},"hub":{"state":{"work_id":"9b1a8da3-efa1-4520-92c8-ce85dcf68cfa","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":25,"external_cited_by_count":null,"distinct_field_count":3,"first_pith_cited_at":"2025-03-18T21:14:12+00:00","last_pith_cited_at":"2026-05-20T17:46:56+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-06-01T10:43:23.677716+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":18},{"context_role":"method","n":3}],"polarity_counts":[{"context_polarity":"background","n":17},{"context_polarity":"use_method","n":3},{"context_polarity":"unclear","n":1}],"runs":{},"summary":{},"graph":{},"authors":[]}}