Better Accuracy and robusTness for Mass Assessment of Neutrino – BATMAN

In the Standard Model of particle physics, the neutrino sector is still not fully understood; in particular, the mechanism by which neutrinos acquire their mass is currently unknown. The model proposes three neutrino flavours with three different eigenstates of mass introducing mixing between them. While the difference of the eigenstates’ masses is well constrained via neutrino oscillation experiments (solar, atmospheric, reactor, and accelerator), cosmology offers a unique unrivalled way to test the Standard Model of particle physics by measuring the absolute neutrino mass scale. At the time of precision cosmology, while the current constraints are starting to reach the theoretical limits for the hierarchy of neutrinos, the goal of this proposal is to provide a robust estimate of the neutrino masses taking into account all relevant physical and statistical effects that can impact cosmological constraints. To achieve robust constraints on neutrino properties from CMB observations, BATMAN will address three ambitious goals with a working plan based on three pillars: a coherent secondary anisotropy model, a robust description of the reionisation history, a complete CMB likelihood for massive neutrinos. The coherent use of CMB data, physical models of secondary contributions and extragalactic probes, as well as the propagation of theoretical and astrophysical systematic uncertainties, will allow a robust estimate of the neutrino mass and a potential determination of the neutrino hierarchy.