Dominant two-loop electroweak corrections to the hadroproduction of a pseudoscalar Higgs boson and its photonic decay

Abstract

We present the dominant two-loop electroweak corrections to the partial decay widths to gluon jets and prompt photons of the neutral $CP$-odd Higgs boson ${A}^{0}$, with mass ${M}_{{A}^{0}}<2{M}_{W}$, in the two-Higgs-doublet model for low to intermediate values of the ratio $\mathrm{tan}\ensuremath{\beta}={v}_{2}/{v}_{1}$ of the vacuum expectation values. They apply as they stand to the production cross sections in hadronic and two-photon collisions, at the Tevatron, the LHC, and a future photon collider. The appearance of three ${\ensuremath{\gamma}}_{5}$ matrices in closed fermion loops requires special care in the dimensional regularization of ultraviolet divergences, and the finite electroweak renormalization of the pseudoscalar current restoring the anticommutativity of ${\ensuremath{\gamma}}_{5}$ is performed for the first time. The corrections are negative and amount to several percent, so that they fully compensate or partly screen the enhancement due to QCD corrections.