QED corrections to the thermal neutrino interaction rate

A bstract Motivated by precision computations of neutrino decoupling at MeV temperatures, we show how QED corrections to the thermal neutrino interaction rate can be related to the electron-positron spectral function as well as an effective ν ̄ν γ vertex. The spectral function is needed both in a timelike and in a spacelike domain, and for both of its physical polarization states (transverse and longitudinal with respect to spatial momentum). Incorporating an NLO evaluation of this spectral function, an estimate of the ν ̄ν γ vertex, and HTL resummation of scatterings mediated by soft Bose-enhanced t -channel photons, we compute the interaction rate as a function of the neutrino momentum and flavour. Effects on the – (0 . . . 2)% level are found, noticeably smaller than a previous estimate of a related quantity.