arXiv subjects

Sophie Kollatzsch

Publications and source records attributed to Sophie Kollatzsch.

6 recordsLinked to original sources

arXiv2026

Radiative pion-pair production in disperon QED

Based on the previously developed disperon QED method for incorporating data input into loop processes in Monte Carlo codes, we calculate $ee\toππγ$ at NLO and include the pion vector form factor within the form-factor scalar QED approximation wherever it is physically justified. By also considering contributions beyond, for which the form-factor scalar QED approach is less well justified, we gain insight into the associated theory uncertainty for selected experimental scenarios. All calculations are implemented and made available within the Monte Carlo framework McMule.

hep-ph↗

arXiv2026

Disperon QED

We present disperon QED, a method to deal with data input in loop processes in Monte Carlo codes. It relies on dispersion relations, automated tools such as OpenLoops, effective field theory methods and a threshold subtraction. We motivate this method and apply it to the process $ee\toππ$ in McMule to deal with hadronic vacuum polarisation insertions in two-loop contributions as well as the vector form factor of the pion within the form-factor scalar QED approximation. The generality of this method for more complicated processes is emphasised.

hep-ph↗

arXiv2026

Beyond QED: Electroweak and hadronic extensions of McMule

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.

hep-ph↗

arXiv2025

Parity violation in Møller scattering within low-energy effective field theory

We include electroweak effects in Moller scattering at low energies in an effective field theory approach and compute the left-right parity-violating asymmetry. The calculation using low-energy effective field theory provides a solid framework to integrate out heavy particles with masses of the order of the electroweak scale, allowing the resummation of all large logarithms between the electroweak scale and the scale, where QCD perturbation theory breaks down. The NLO electroweak corrections with leading logarithmic resummation, combined with QED corrections at NNLO and hadronic effects are implemented into the Monte Carlo framework McMule. Thus, we obtain a fully differential description and present results adapted to the MOLLER experiment. The potential impact of large logarithms at the next-to-leading logarithmic level is investigated.

hep-ph↗

arXiv2025

Radiative corrections and Monte Carlo tools for low-energy hadronic cross sections in $e^+ e^-$ collisions

We present the results of Phase I of an ongoing review of Monte Carlo tools relevant for low-energy hadronic cross sections. This includes a detailed comparison of Monte Carlo codes for electron-positron scattering into a muon pair, pion pair, and electron pair, for scan and radiative-return experiments. After discussing the various approaches that are used and effects that are included, we show differential cross sections obtained with AfkQed, BabaYaga@NLO, KKMC, MCGPJ, McMule, Phokhara, and Sherpa, for scenarios that are inspired by experiments providing input for the dispersive evaluation of the hadronic vacuum polarisation.

hep-ph↗

arXiv2023

Lepton pair production at NNLO in QED with EW effects

We present a fully differential calculation of lepton pair production, taking into account the dominant next-to-next-to-leading order QED corrections as well as next-to-leading order electroweak and polarisation effects. We include all lepton masses, hard photon emission, as well as non-perturbative hadronic corrections. The corresponding matrix elements are implemented in the Monte Carlo framework McMule. In order to obtain a numerically stable implementation, we extend next-to-soft stabilisation, a universal technique based on a next-to-leading-power expansion, to calculations with polarised leptons. As an example, we show results tailored to the Belle II detector with the current setup as well as a potential future configuration that includes polarised beams.

hep-ph↗