  The temperature of sphaleron freeze-out, $T\approx 130$ GeV, sets a scale for
mechanisms for generating lepton asymmetries and converting them to baryon
asymmetry (leptogenesis). For Majorana masses $M \gg \pi T$, leptogenesis takes
place in the non-relativistic regime, while for $M \ll \pi T$, the dynamics is
ultrarelativistic. The intermediate case $M \sim \pi T$ is the most cumbersome,
as no effective theory methods are available. We review the definitions of and
provide integral representations for all rate coefficients and mass corrections
of $\mathcal{O}(h_\nu^2)$ in this regime, such that the expressions extrapolate
to known limits and are gauge independent to the order computed, both in the
symmetric and the Higgs phase, for any helicity, momentum, and set of chemical
potentials. Road signs towards a numerical evaluation are offered.
