Negative Masses and Spatial Curvature: Alleviating Neutrino Mass Tensions in LambdaCDM and Extended Cosmologies

Negative Masses and Spatial Curvature: Alleviating Neutrino Mass Tensions in LambdaCDM and Extended Cosmologies
Hayyim Pulido-Hern’andez, Jorge L. Cervantes-Cota
arXiv:2603.13208v1 Announce Type: new
Abstract: We investigate the impact of spatial curvature, $Omega_k$, and dynamical dark energy on the cosmological constraints of the neutrino mass sum, $sum m_nu$. Using a joint analysis of the latest CMB (Planck and ACT DR6), BAO (DESI DR2) and SNe Ia (DESY5 and DES-Dovekie) datasets, we perform an exploration of the neutrino mass parameter space. To mitigate prior-driven biases near the physical boundary, we implement a symmetric extension wrapper that allows for effective negative masses. We find that the inclusion of spatial curvature significantly modifies the posterior distributions, exhibiting a smooth transition across the $sum m_nu = 0$ threshold. In the $Lambda$CDM + $Omega_k$ + $sum m_{nu,mathrm{eff}}$ framework, we obtain $sum m_{nu,mathrm{eff}} = -0.011^{+0.052}_{-0.050}$, reducing the tension with the terrestrial lower limit of 0.06 eV from $2.59sigma$ for the $Lambda$CDM + $sum m_{nu,mathrm{eff}}$ model to $1.17sigma$. For the most flexible scenario $w_0 w_a$CDM + $Omega_k$ + $sum m_{nu,mathrm{eff}}$, we find $sum m_{nu,mathrm{eff}} = -0.07 pm 0.11$ with a tension of $1.13sigma$, illustrating how the increased parameter freedom notably degrades the precision of the mass estimate compared to simpler extensions. Our results demonstrate that current cosmological bounds on $sum m_nu$ are heavily influenced by boundary effects and geometric degeneracies.arXiv:2603.13208v1 Announce Type: new
Abstract: We investigate the impact of spatial curvature, $Omega_k$, and dynamical dark energy on the cosmological constraints of the neutrino mass sum, $sum m_nu$. Using a joint analysis of the latest CMB (Planck and ACT DR6), BAO (DESI DR2) and SNe Ia (DESY5 and DES-Dovekie) datasets, we perform an exploration of the neutrino mass parameter space. To mitigate prior-driven biases near the physical boundary, we implement a symmetric extension wrapper that allows for effective negative masses. We find that the inclusion of spatial curvature significantly modifies the posterior distributions, exhibiting a smooth transition across the $sum m_nu = 0$ threshold. In the $Lambda$CDM + $Omega_k$ + $sum m_{nu,mathrm{eff}}$ framework, we obtain $sum m_{nu,mathrm{eff}} = -0.011^{+0.052}_{-0.050}$, reducing the tension with the terrestrial lower limit of 0.06 eV from $2.59sigma$ for the $Lambda$CDM + $sum m_{nu,mathrm{eff}}$ model to $1.17sigma$. For the most flexible scenario $w_0 w_a$CDM + $Omega_k$ + $sum m_{nu,mathrm{eff}}$, we find $sum m_{nu,mathrm{eff}} = -0.07 pm 0.11$ with a tension of $1.13sigma$, illustrating how the increased parameter freedom notably degrades the precision of the mass estimate compared to simpler extensions. Our results demonstrate that current cosmological bounds on $sum m_nu$ are heavily influenced by boundary effects and geometric degeneracies.