Leading fermionic three-loop corrections to electroweak precision observables

• Main Authors: Lisong Chen, Ayres Freitas
• Format: Article
• Language: English
• Published: SpringerOpen 2020-07-01
• Series: Journal of High Energy Physics
• Subjects: Quark Masses and SM Parameters; Scattering Amplitudes
• Online Access: http://link.springer.com/article/10.1007/JHEP07(2020)210

Abstract Future electron-position colliders, such as the CEPC, FCC-ee, and ILC have the capability to dramatically improve the experimental precision for W and Z-boson masses and couplings. This would enable indirect probes of physics beyond the Standard Model at multi-TeV scales. For this purpose, one must complement the experimental measurements with equally precise calculations for the theoretical predictions of these quantities within the Standard Model, including three-loop electroweak corrections. This article reports on the calculation of a subset of these corrections, stemming from diagrams with three closed fermion loops to the following quantities: the prediction of the W-boson mass from the Fermi constant, the effective weak mixing angle, and partial and total widths of the Z boson. The numerical size of these corrections is relatively modest, but non-negligible compared to the precision targets of future colliders. In passing, an error is identified in previous results for the two-loop corrections to the Z width, with a small yet non-zero numerical impact.