One-Loop Single-Real-Emission Contributions to $ppto H + X$ at Next-to-Next-to-Next-to-Leading Order

I compute the contributions of the one-loop single-real-emission amplitudes, $ggto H g$, $qgto H q$, etc., to inclusive Higgs boson production through next-to-next-to-next-to-leading order (N^3LO) in the strong coupling $alpha_s$. The next-to-leading (NLO) and next-to-next-to-leading order (NNLO) terms are computed in closed form, in terms of $Gamma$-functions and the hypergeometric functions ${}_{2}F_{1}$ and ${}_{3}F_{2}$. I compute the nnlo terms as Laurent expansions in the dimensional regularization parameter through order $(epsilon^{1})$. To obtain the nnlo terms, I perform an extended threshold expansion of the phase space integrals and map the resulting coefficients onto a basis of harmonic polylogarithms.