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Measuring neutrino mass in light of ACT DR6 and DESI DR2

Lu Feng, Tian-Nuo Li, Guo-Hong Du, Jing-Fei Zhang, Xin Zhang

Abstract

The recent release of high-precision cosmological data, particularly the small-scale cosmic microwave background (CMB) measurements from ACT and baryon acoustic oscillation (BAO) data from DESI, has opened a new landscape for probing the neutrino mass. In this work, we present updated constraints on the total neutrino mass, $\sum m_ν$, and its hierarchy within the $Λ$CDM, $w$CDM, holographic dark energy (HDE), and $w_0w_a$CDM models, using the latest ACT DR6, DESI DR2, and DESY5 datasets. We find that the upper limits on $\sum m_ν$ are critically governed by the evolutionary behavior of the dark energy equation of state. Specifically, models exhibiting early-time quintessence features (e.g., HDE) yield the most stringent constraints, whereas those allowing for early-time phantom behavior (e.g., $w_0w_a$CDM) result in significantly looser bounds. Despite these model-dependent variations, we observe a robust hierarchy dependence across all scenarios, where the inverted hierarchy consistently yields weaker constraints and the degenerate hierarchy consistently yields tightest constraints. Our analysis demonstrates that the improved small-scale CMB information from ACT, combined with high-precision BAO data, systematically tightens the limits on $\sum m_ν$, providing a crucial benchmark for future neutrino mass measurement.

Measuring neutrino mass in light of ACT DR6 and DESI DR2

Abstract

The recent release of high-precision cosmological data, particularly the small-scale cosmic microwave background (CMB) measurements from ACT and baryon acoustic oscillation (BAO) data from DESI, has opened a new landscape for probing the neutrino mass. In this work, we present updated constraints on the total neutrino mass, , and its hierarchy within the CDM, CDM, holographic dark energy (HDE), and CDM models, using the latest ACT DR6, DESI DR2, and DESY5 datasets. We find that the upper limits on are critically governed by the evolutionary behavior of the dark energy equation of state. Specifically, models exhibiting early-time quintessence features (e.g., HDE) yield the most stringent constraints, whereas those allowing for early-time phantom behavior (e.g., CDM) result in significantly looser bounds. Despite these model-dependent variations, we observe a robust hierarchy dependence across all scenarios, where the inverted hierarchy consistently yields weaker constraints and the degenerate hierarchy consistently yields tightest constraints. Our analysis demonstrates that the improved small-scale CMB information from ACT, combined with high-precision BAO data, systematically tightens the limits on , providing a crucial benchmark for future neutrino mass measurement.
Paper Structure (9 sections, 6 equations, 3 figures, 1 table)

This paper contains 9 sections, 6 equations, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. Dark energy models
  3. The $\Lambda$CDM model
  4. The $w$CDM model
  5. The HDE model
  6. The $w_0w_a$CDM model
  7. Data and method
  8. Results and discussion
  9. Conclusion

Figures (3)

  • Figure 1: The $1\sigma$ and $2\sigma$ credible-interval contours showing the correlations between $\sum m_\nu$ and the DE parameters ($w$, $c$, $w_0$, and $w_a$) for the $w$CDM, HDE, and $w_0w_a$CDM models in the DH, NH, and IH cases, obtained from the CMB+BAO+SN data.
  • Figure 2: The one-dimensional marginalized posterior constraints on $\sum m_\nu$ using the CMB+BAO+SN datasets in different DE models and neutrino hierarchies.
  • Figure 3: The $1\sigma$ and $2\sigma$ credible-interval contours of $\sum m_\nu$, $\Omega_{\rm m}$ and $H_0$ for the $\Lambda$CDM, $w$CDM, HDE and $w_0w_a{\rm CDM}$ models in the DH, NH, and IH cases, derived from the CMB+BAO+SN data.