Sensitivity of Next-Generation CMB Surveys to Neutrinos and Other Light Relics

arXiv:2608.07453 · astro-ph.CO, astro-ph.IM, hep-ph, hep-th · Submitted 2026-08-07 · Read on arXiv

Cynthia Trendafilova, Srinivasan Raghunathan, Benjamin Wallisch, Joel Meyers, Kevork N. Abazajian, Edoardo Altamura, Carlo Baccigalupi, Kimberly K. Boddy, Thejs Brinckmann, Yuji Chinone, Gabriele Coppi, Francis-Yan Cyr-Racine, Jacques Delabrouille, Katherine Freese, Helena García Escudero, Martina Gerbino, Shamik Ghosh, Vera Gluscevic, Daniel Green, Daniel Grin, Kevin M. Huffenberger, Mudit Jain, Lloyd Knox, Anto I. Lonappan, Marilena Loverde, Philip Lubin, Gabriele Montefalcone, Valentine Novosad, Marco Raveri, Christian L. Reichardt, Sayan Saha, Murali M. Saravanan, Emmanuel Schaan, Sara M. Simon, Julien Tang, Scott Watson

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astro-ph.CO, astro-ph.IM, hep-ph, hep-th

Submitted: 2026-08-07

Updated: 2026-08-10

Comments: 76 pages, 8 figures, 8 tables; DRAFT forecasting tool available at https://github.com/sriniraghunathan/DRAFT

Code: https://github.com/sriniraghunathan/DRAFT

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Terminology

• Abundance — 36× in this paper · explained in 1 episode
• Decoupling — 33× in this paper · explained in 2 episodes
• Reheating — 21× in this paper · explained in 2 episodes
• Simons Observatory — 14× in this paper
• Aperture — 11× in this paper · explained in 1 episode
• Degeneracy — 11× in this paper · explained in 3 episodes
• Anisotropy — 8× in this paper · explained in 3 episodes
• Consistency — 6× in this paper · explained in 3 episodes
• Fisher Information — 6× in this paper · explained in 3 episodes
• Phase Transitions — 6× in this paper · explained in 2 episodes
• South Pole Telescope — 6× in this paper
• Benchmark — 5× in this paper · explained in 2 episodes
• Spectral Distortions — 5× in this paper · explained in 2 episodes
• Fidelity — 4× in this paper · explained in 2 episodes
• Gravitational Lensing — 4× in this paper · explained in 2 episodes
• Symmetry Breaking — 4× in this paper · explained in 3 episodes
• US Department of Energy — 4× in this paper
• Adam — 3× in this paper · explained in 2 episodes
• Clustering — 3× in this paper · explained in 2 episodes
• Hubble Tension — 3× in this paper · explained in 9 episodes
• Matter Power Spectrum — 3× in this paper · explained in 2 episodes
• Dark Radiation Anisotropy Flowdown Team — 2× in this paper
• Frequency Dependence — 2× in this paper · explained in 2 episodes
• National Center for Supercomputing Applications — 2× in this paper
• Probe of Inflation and Cosmic Origins — 2× in this paper
• Baryonic Feedback — 1× in this paper · explained in 3 episodes
• Bispectrum — 1× in this paper · explained in 3 episodes
• Core — 1× in this paper · explained in 2 episodes
• Cosmic Linear Anisotropy Solving System — 1× in this paper
• Generalization — 1× in this paper · explained in 13 episodes
• Model-Agnostic — 1× in this paper · explained in 2 episodes
• National Energy Research Scientific Computing Center — 1× in this paper
• National Science Foundation — 1× in this paper
• National Supercomputer Centre — 1× in this paper
• Packed Ultra-wideband Mapping Array — 1× in this paper
• Systematic Bias — 1× in this paper · explained in 3 episodes
• Weak Lensing — 1× in this paper · explained in 2 episodes

Sources

• Snowmass Theory Frontier: Astrophysics and Cosmology
• Report of the Topical Group on Cosmic Frontier 5 Dark Energy and Cosmic Acceleration: Cosmic Dawn and Before for Snowmass 2021
• TASI Lectures on Cosmic Signals of Fundamental Physics
• Messengers from the Early Universe: Cosmic Neutrinos and Other Light Relics
• Synergy between cosmological and laboratory searches in neutrino physics
• The Physics of Light Relics
• Prospects and Limitations for Constraining Light Relics with Primordial Abundance Measurements
• Primordial Deuterium after LUNA: concordances and error budget
• The Impact of New d(p,\gamma)He3 Rates on Big Bang Nucleosynthesis
• EMPRESS. VIII. A New Determination of Primordial He Abundance with Extremely Metal-Poor Galaxies: A Suggestion of the Lepton Asymmetry and Implications for the Hubble Tension
• Probing Physics Beyond the Standard Model: Limits from BBN and the CMB Independently and Combined
• EMPRESS. XV. A New Determination of the Primordial Helium Abundance Suggesting a Moderately Low $Y_\mathrm{P}$ Value
• The LBT $Y_{\rm p}$ Project V: Cosmological Implications of a New Determination of Primordial $^4$He
• Precision big bang nucleosynthesis with improved Helium-4 predictions
• Big Bang Nucleosynthesis and Neutrino Cosmology
• Big-Bang Nucleosynthesis After Planck
• Big Bang Nucleosynthesis
• Big Bang Nucleosynthesis
• Searching for Light Relics with Large-Scale Structure
• Cosmology in the era of Euclid and the Square Kilometre Array

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