Bosonic corrections to the effective weak mixing angle at O(α2)

We present the complete bosonic contributions to the effective weak mixing angle, sin(2)theta(lept)(eff), at the two-loop level in the electroweak interactions. We find their size to be about three times smaller than inferred from simple estimates from lower orders. In particular, for a Higgs boson mass, M-H, of 100 GeV they amount to 4 x 10(-6), and drop down by about an order of magnitude for M-H = 200 GeV. We estimate the intrinsic error of the theory prediction of sin(2)theta(lept)(eff) (c) 2006 Elsevier B.V. All rights reserved.