The effective electroweak mixing angle ${\sin }^2{\theta }_{eff}$ with two-loop fermionic contributions

Abstract

We present the results from a calculation of the full electroweak two-loop fermionic contributions to the effective leptonic mixing angle of the $Z$ boson, ${\sin }^2{\theta }_{eff}$, in the Standard Model. On-shell renormalization and analytic calculations are performed for the three-point vertex functions at zero external momenta, whereas irreducible three-point integrals for non-vanishing external momenta are evaluated semi-analytically applying two different methods. Comparisons with a previous calculation show complete agreement.

Comments: 15 pages, 5 figures, reference added, few typos corrected