Box integrals with fermion bubbles for low-energy measurements of the weak mixing angle

Abstract

AbstractThe Moller experiment and the P2 experiment aim at measuring the weak mixing angle at low scales. The Moller experiment uses $$e^- e^- \rightarrow e^- e^-$$ e - e - → e - e - -scattering, the P2 experiment uses $$e^- N \rightarrow e^- N$$ e - N → e - N -scattering. In both cases, two-loop electroweak corrections have to be taken into account, and here in particular diagrams which give rise to large logarithms. In this paper we compute a set of two-loop electroweak Feynman integrals for point-like particles, which are obtained from a box integral by the insertion of a light fermion loop. By rationalising all occurring square roots we show that these Feynman integrals can be expressed in terms of multiple polylogarithms. We present the results in a form, which makes the large logarithms manifest. We provide highly efficient numerical evaluation routines for these integrals.