Could inflation-era neutrinos leave fingerprints in the primordial sky?

During inflation, right-handed neutrinos — particles invoked to explain why ordinary neutrinos have such tiny masses — could have briefly existed and left imprints on the statistical patterns of primordial density fluctuations. A chemical-potential-like effect tied to the inflaton field preferentially produces one neutrino helicity, dramatically reducing the usual exponential suppression that makes heavy particles nearly invisible. This means future surveys measuring primordial non-Gaussianity could, in principle, probe neutrino physics at energy scales far beyond any terrestrial collider.