Beyond QED: Electroweak and hadronic extensions of McMule
Sophie Kollatzsch
备注：
11 pages, 3 figures, contribution to the 17th International Symposium on Radiative Corrections: Applications of Quantum Field Theory to Phenomenology (RADCOR2025), 5-10 October 2025, Puri, India
McMule is a Monte Carlo framework developed to advance the low-energy precision frontier by providing QED corrections to leptonic scattering and decay processes, currently up to next-to-next-to-leading order. Recent developments have extended its capabilities in two important directions: the systematic inclusion of electroweak effects at low energies within the low-energy effective field theory [arXiv:2507.17652], and the incorporation of pion form factors and the non-perturbative hadronic vacuum polarisation in loop amplitudes through a combination of OpenLoops and effective field theory techniques, referred to as disperon QED [arXiv:2512.10709]. I will provide an overview of McMule and discuss these recent extensions and their applications. In particular, I will illustrate the impact of the model used for non-perturbative $γ$-$Z$ mixing effects in the context of the MOLLER experiment and highlight the subtlety involved in consistently aligning OpenLoops with its effective field theory expansion in disperon QED.
McMule is a framework for fully differential higher-order QED calculations of scattering and decay processes involving leptons. It keeps finite lepton masses, which regularises collinear singularities. Soft singularities are treated with dimensional regularisation and using FKS$^\ell$ subtraction. We describe the implementation of the framework in Fortran 95, list the processes that are currently implemented, and give instructions on how to run the code. In addition, we present new phenomenological results for muon-electron scattering and lepton-proton scattering, including the dominant NNLO c…
We present McMule, a unified framework for the calculation of NLO and NNLO corrections to many processes in QED with massive fermions. This easily extendable program allows users to calculate an arbitrary observable for any of the processes implemented. These include various lepton decays as well as certain low-energy scattering experiments such as $eμ\to eμ$ and $\ell p\to\ell p$ that can be measured to high enough a precision to warrant QED corrections. As part of our discussion, we will present a pedagogical introduction to how these calculations are performed, focusing on technical aspects…
Kantonsschule Menzingen（门津根州立中学）；Università degli Studi di Torino & INFN（瑞士保罗谢尔研究所中子与缪子科学中心）；Physik-Institut, Universität Zürich（苏黎世大学物理学院）；University of Liverpool（利物浦大学）
该研究在 QED 框架下实现了低能 $e^+\,e^-\toγ\,γ$ 过程的 NNLO 计算，为电子-正电子对撞机的亮度测量提供了理论支持。
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It might be expected that only global symmetries are fundamental symmetries of Nature, whereas local symmetries and associated massless gauge fields could solely emerge due to spontaneous breaking of underlying spacetime symmetries involved, such as relativistic invariance and supersymmetry. This breaking, taken in the form of the nonlinear sigma-model type pattern for vector fields or superfields, puts essential restrictions on geometrical degrees of freedom of a physical field system that makes it to adjust itself in such a way that its global internal symmetry G turns into the local symmetr…
