Two-loop electroweak corrections to the image and image couplings of the CP-odd Higgs boson Original Research Article

Using the asymptotic-expansion technique, we compute the dominant two-loop electroweak corrections, of image, to production and decay via a pair of photons or gluons of the CP-odd Higgs boson image in a two-Higgs-doublet model with low to intermediate values of the Higgs-boson masses and ratio image of the vacuum expectation values. We also study the influence of a sequential heavy-fermion generation. The appearance of three image matrices in closed fermion loops requires special care in the dimensional regularisation of ultraviolet divergences. The finite renormalisation constant for the pseudoscalar current effectively restoring the anticommutativity of the image matrix, familiar from perturbative quantum chromodynamics, is found not to receive a correction in this order. We also revisit the dominant two-loop electroweak correction to the image decay width in the Standard Model with a fourth fermion generation.