A thermal neutrino interaction rate at NLO

TL;DR

This paper calculates the next-to-leading order correction to the thermal neutrino interaction rate at high temperatures, revealing a significant reduction that impacts leptogenesis models.

Contribution

It provides the first NLO calculation of the ultrarelativistic neutrino interaction rate in the high-temperature regime relevant for leptogenesis.

Findings

NLO correction reduces the interaction rate by 15-40%.

The correction causes about a 1% decrease in lepton asymmetry production.

The method uses a Euclideanization property of a thermal light-cone correlator.

Abstract

The interaction rate of an ultrarelativistic active neutrino at a temperature below the electroweak crossover plays a role in leptogenesis scenarios based on oscillations between active neutrinos and GeV-scale sterile neutrinos. By making use of a Euclideanization property of a thermal light-cone correlator, we determine the $O(g)$ correction to such an interaction rate in the high-temperature limit $\pi T \gg m_W$, finding a $\sim 15 ... 40\%$ reduction. For a benchmark point, this NLO correction decreases the lepton asymmetries produced by $\sim 1\%$.