Revealing New Physics Through Primordial Neutrinos

ongoing

Primordial neutrinos are key messengers from the Early Universe, offering a probe of the cosmic times as small as 0.01 seconds after the Big Bang. This represents a key test of both the standard models of particle physics and cosmology. Upcoming Cosmic Microwave Background (CMB) observations will achieve unprecedented precision in measuring neutrino properties, potentially revealing or constraining new physics. Establishing this linkage requires a unified, efficient, model-independent approach to solving the neutrino Boltzmann equation in the presence of new physics. Current studies lack all these features, resulting in a fragmented, limited, and opaque state-of-the-art. This project will systematically study the effects of various new physics scenarios on primordial neutrinos and their impact on CMB, Big Bang Nucleosynthesis (BBN), and baryon acoustic oscillations. It will develop a novel approach to solving the neutrino Boltzmann equation using an improved Direct Simulation Monte Carlo method, addressing limitations in current methods. Several new physics models will be considered within the approach, including decaying particles (like Heavy Neutral Leptons and late reheating particles) and non-standard neutrino interactions. The analysis will culminate in CosmoCalc, a framework to map new physics models to neutrino properties and primordial abundances, calculating cosmological constraints and/or sensitivities. It will also integrate cosmological observations with laboratory searches to refine the parameter space for new physics, guiding future accelerator experiments like SHiP. By providing results and tools open-access, this project will connect theoretical predictions with observational data, enhance interdisciplinary collaboration, and improve the interpretation of high-precision measurements from upcoming cosmological missions, paving the way for future exploration of the universe's fundamental properties.