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Peter Meinzinger

Publications and source records attributed to Peter Meinzinger.

12 recordsLinked to original sources
arXiv2026

Automated higher-order predictions for ultra-peripheral collisions with full impact-parameter dependence

We present an automated framework within the Sherpa event generator for the simulation of photon-induced processes in high-energy collisions of protons and nuclei. The calculation builds upon the equivalent-photon approximation and incorporates different form factor parametrisations, taking into account the full dependence on the finite size of emitters and their impact parameter. Higher-order effects are taken into account automatically by either YFS-resummation of soft photon emissions to all orders or Next-to-Leading Order in electroweak theory. We validate our simulation framework using data from two representative ATLAS measurements of exclusive $\mu$-pair production in $pp$ and Pb+Pb collisions. Exemplary predictions for exclusive $W$-pair production in $pp$ collisions and $\tau$-pair production in both $pp$ and Pb+Pb collisions are presented.

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arXiv2026

Event generation for future DIS experiments

In this contribution we discuss state-of-the-art hadron-level predictions for the deep-inelastic scattering process at next-to-leading-order precision for several multiplicities, consistently merged in one sample. We focus on the physics at (potential) future colliders, the Electron-Ion Collider planned at BNL as well as the higher energy experiments discussed as future options at CERN, a LHeC and a DIS phase of the Future Circular Collider dubbed FCC-eh.

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arXiv2026

Photoproduction in general-purpose event generators

We compare the three general-purpose Monte Carlo event generators, HERWIG, PYTHIA, and SHEPRA for jet photoproduction processes in $e^+e^-$ and $ep$ collisions. Due to the lower energy scales probed, photoproduction is particularly sensitive to non-perturbative corrections. In a systematic analysis we disentangle and quantify the differences between the generators in these processes, i.e. contributions from beam remnants, parton showers, multiparton interactions (MPIs), and hadronisation modelling. We outline the default inputs and implementation differences and compare the computations with experimental data from LEP and HERA. We find that all generators provide a decent description of the data within the uncertainties, with particularly good descriptions by the LO-accurate PYTHIA and the NLO-accurate SHERPA. Finally, we also present predictions for the upcoming EIC for jet observables and event shapes and conclude that a modern global refit of the photon parton distributions and dedicated experimental measurements ported to the RIVET framework to constrain non-perturbative parameters are the key prerequisites for precision photoproduction phenomenology at the EIC.

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arXiv2026

Photon-induced jet production at future lepton colliders

The production of hadronic final states in electron-positron or electron-hadron collisions is induced predominantly by quasi-real photons that were emitted off incoming leptons. In these processes, the photon either enters directly or through its resolved parton content, which is at present only loosely constrained by experimental data. We perform a detailed phenomenological study of photon-induced jet production processes in high-energy $e^+e^-$ collisions, investigating in particular their potential to assess contributions from the resolved photon structure.

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arXiv2025

Event generation at MEPS@NLO accuracy in neutral and charged current DIS at the EIC

We present state-of-the-art hadron-level predictions for the deep-inelastic scat- tering process at next-to-leading-order precision for several multiplicities, con- sistently merged in one sample. For the first time at this level of accuracy, we consider both neutral and charged current deep-inelastic scattering at the Electron-Ion Collider, and present the first application of consistent next-to- leading-order merging to charged current deep-inelastic scattering in general. We critically examine inclusive predictions using multileg merging techniques, contrasting perturbative and nonperturbative uncertainties. Further, we study typical kinematic deep-inelastic scattering observables as well as jet measure- ments and 1-jettiness with realistic cuts implied by expected and past detector resolution. On the perturbative side, we see large corrections toward small vir- tualities and Bjorken-x, which can be captured by higher-multiplicity matrix elements and the merging procedure. Nonperturbative effects, while negligible in most jet observables, can reach similar size as the perturbative uncertainties around the peak of the 1-jettiness distributions especially at low values of $Q^2$ .

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arXiv2025

Recoil-Safe Subtraction, Matching and Merging in e+e- to hadrons

We present the first next-to-leading order matched and multi-jet merged predictions based on the Alaric parton shower. The components needed for infrared subtraction in the S-MC@NLO algorithm are computed analytically for the case of color singlet decays to hadronic final states and validated against existing approaches for up to e+e- to 5 jets. Phenomenological results for e+e- to hadrons at the Z pole are obtained with up to five jets at next-to-leading order precision, for the first time using an evolution algorithm with NLL-preserving kinematics mapping.

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arXiv2024

Event generation with Sherpa 3

Sherpa is a general-purpose Monte Carlo event generator for the simulation of particle collisions in high-energy collider experiments. We summarise new developments, essential features, and ongoing improvements within the Sherpa 3 release series. Physics improvements include higher-order electroweak corrections, simulations of photoproduction and hard diffraction at NLO QCD, heavy-flavour matching in NLO multijet merging, spin-polarised cross section calculations, and a new model of colour reconnections. In addition, the modelling of hadronisation, the underlying event and QED effects in both production and decay has been improved, and the overall event generation efficiency has been enhanced.

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arXiv2024

Full event simulation of Photoproduction at NLO QCD in Sherpa

Photoproduction is an important mode for the production of jets and electro-weak particles at lepton--lepton and lepton--hadron colliders and allows for interesting studies of exclusive production at hadron--hadron colliders. In this talk, I will review recent efforts of extending the Sherpa event generator to include the calculation of photoproduction cross sections for electron and proton beams, including the simulation of underlying events. The framework is validated using data of jet production at the HERA and LEP experiments and lepton production at the LHC. I will discuss advances towards achieving matched NLO accuracy and fully capturing the dynamics of inclusive and exclusive photoproduction at different colliders.

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arXiv2024

Hard Diffraction in Sherpa

We present the first complete simulation framework for the simulation of jet production in diffractive events at next-to leading order in QCD, matched to the parton shower. We validate the implementation in the SHERPA event generator with data from the H1 and ZEUS experiments for diffractive DIS and diffractive photoproduction. For the latter, we review different models aiming to explain the observed factorisation breaking and we argue that at NLO the direct component must also be suppressed. We provide predictions for diffractive jet production both in DIS and in photoproduction events for the upcoming EIC.

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arXiv2023

Resolved Photons in Sherpa

We present the first complete simulation framework, in the Sherpa event generator, for resolved photon interactions at next-to leading order accuracy. It includes photon spectra obtained through the equivalent-photon approximation, parton distribution functions to parametrize the hadronic structure of quasi-real photons, the matching of the parton shower to next-to leading order QCD calculations for resolved photon cross sections, and the modelling of multiple-parton interactions. We validate our framework against a wide range of photo-production data from LEP and HERA experiments, observing good overall agreement. We identify important future steps relevant for high-quality simulations at the planned Electron-Ion Collider.

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arXiv2021

A unified leptoquark model confronted with lepton non-universality in $B$-meson decays

The anomalies in the $B$-meson sector, in particular $R_{K^{(*)}}$ and $R_{D^{(*)}}$, are often interpreted as hints for physics beyond the Standard Model. To this end, leptoquarks or a heavy $Z'$ represent the most popular SM extensions which can explain the observations. However, adding these fields by hand is not very satisfactory as it does not address the big questions like a possible embedding into a unified gauge theory. On the other hand, light leptoquarks within a unified framework are challenging due to additional constraints such as lepton flavor violation. The existing accounts typically deal with this issue by providing estimates on the relevant couplings. In this letter we consider a complete model based on the $SU(4)_{\rm C}\otimes SU(2)_{\rm L}\otimes U(1)_{\rm R}$ gauge symmetry, a subgroup of $SO(10)$, featuring both scalar and vector leptoquarks. We demonstrate that this setup has, in principle, all the potential to accommodate $R_{K^{(*)}}$ and $R_{D^{(*)}}$ while respecting bounds from other sectors usually checked in this context. However, it turns out that $K_L \to e^{\pm} μ^{\mp}$ severely constraints not only the vector but also the scalar leptoquarks and, consequently, also the room for any sizeable deviations of $R_{K^{(*)}}$ from 1. We briefly comment on the options for extending the model in order to conform this constraint. Moreover, we present a simple criterion for all-orders proton stability within this class of models.

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