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arXiv · 2510.15835

Constraints on neutrino mass and dark energy agnostic to the sound horizon

Ravi Kumar Sharma·Julien Lesgourgues
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Abstract

Recent BAO observations from DESI DR2 either hint at a possible dynamical dark energy component, which would worsen the Hubble tension, or at a 95\% credible interval for the summed neutrino mass hardly compatible with neutrino oscillation experiments. In this context, it is interesting to investigate constraints on neutrino masses, dark energy and the Hubble parameter that are agnostic to some aspects of the cosmological model. Here we choose to be agnostic to the value of the sound horizon at recombination, while sticking to standard assumptions regarding the time of recombination and the growth of structures. To be consistent, we also disregard information on the full shape of the CMB temperature and polarization spectrum on sub-degree scale. With such agnostic and conservative assumptions, using data mainly on uncalibrated distances, the growth of structures, and laboratory bounds on tritium $β$-decay, we find that: (i) the dark energy evolution is well constrained by uncalibrated data on angular and luminosity distances, with a mild preference for dynamical dark energy, independently of the value of the sound horizon; (ii) large values of the Hubble rate are favored, $H_0=74.7^{+3.4}_{-4.4}$ km/s/Mpc (68\%CL), together with low values of the sound horizon, $r_{\rm s}=131.1^{+6.8}_{-6.9}$ Mpc (68\%CL); the SH0ES value of $H_0$ is thus marginally preferred over the low value returned by the standard inverse distance ladder analysis; (iii) the cosmological neutrino mass bound relaxes to $\sum m_ν= 0.69^{+0.33}_{-0.47}$ eV (68\%CL) and becomes well compatible with the normal and inverted neutrino mass schemes.

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Ravi Kumar Sharma, Julien Lesgourgues. 2025-10-24. Constraints on neutrino mass and dark energy agnostic to the sound horizon. https://arxiv.org/abs/2510.15835

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