arXiv subjects

Christian Gütschow

Publications and source records attributed to Christian Gütschow.

13 recordsLinked to original sources

arXiv2026

Environmental sustainability in basic research: a perspective from HECAP+

The climate crisis and the degradation of the world's ecosystems require humanity to take immediate action. The international scientific community has a responsibility to limit the negative environmental impacts of basic research. The HECAP+ communities (High Energy Physics, Cosmology, Astroparticle Physics, and Hadron and Nuclear Physics) make use of common and similar experimental infrastructure, such as accelerators and observatories, and rely similarly on the processing of big data. Our communities therefore face similar challenges to improving the sustainability of our research. This document aims to reflect on the environmental impacts of our work practices and research infrastructure, to highlight best practice, to make recommendations for positive changes, and to identify the opportunities and challenges that such changes present for wider aspects of social responsibility.

physics.soc-ph↗

arXiv2026

AgentRivet: an automated system for producing Rivet routines from journal publications

Particle physics collider experiments provide Rivet routines as part of the analysis preservation strategy for model-independent measurements. Rivet is a C++ toolkit that allow new theoretical models to be compared to the measurements, thus aiding the development and tuning of Monte Carlo event generators as well as searches for physics beyond the Standard Model. However, analysis coverage is known to be incomplete, with only 39% of measurements having documented and publicly available Rivet routines. In this article, we design and implement an automated workflow based on Large Language Models with the goal of providing the missing routines. This multi-step workflow, referred to as AgentRivet, extracts the physics analysis information from published papers and writes the missing Rivet routines, with intermediate code- and physics- reviews as part of an autonomous quality control. We report the results obtained using commercial Large Language Models, provided by OpenAI, Anthropic, and Google, for two recent measurements from the ATLAS and CMS experiments. We find that AgentRivet produces competent Rivet routines with few syntax errors. The physics fidelity of the routines is reasonable and follows the explanations given in the relevant publications. Nevertheless, physics-implementation issues do arise and are investigated using the artefacts produced by AgentRivet. The majority of physics implementation issues arise from subtle-but-ambiguous definitions in the given publication, although some models struggle to implement complex observables even when clear definitions are given.

hep-ex↗

arXiv2026

The Monte Carlo Ecosystem in High-Energy Physics: A Primer

Monte Carlo event generators are the central interface between theoretical calculations and experimental measurements in collider physics. Over several decades, a comprehensive and highly modular ecosystem of tools has developed around them, encompassing matrix-element calculations, parton showers, hadronisation models, and their integration with detector simulation, event-level analysis and statistical inference. While these tools are ubiquitous in modern research, the conceptual scope and technical structure of the full simulation chain can be challenging to navigate, particularly for researchers entering the field. In this primer, we provide a structured and up-to-date overview of the high-energy physics Monte Carlo ecosystem, focusing primarily on event-generator methodologies and their role within the broader collider workflow. We discuss the conceptual foundations of modern generators, the computational and organisational challenges of large-scale simulations, and the principles that enable interoperability and reproducibility across theory and experiment. We also examine the evolving computing landscape and sustainability considerations that will shape the future development of these tools. Aimed primarily at early-stage doctoral researchers while serving as a reference for the broader community, this article seeks to clarify architecture, methodology, and long-term trajectory of Monte Carlo event generation in collider physics.

hep-ph↗

arXiv2026

Open LHC Monte Carlo Event Generation

The LHC physics programme involves a vast amount of Monte Carlo event simulation. This paper reviews current efforts towards sharing the generated events as Open Data. Open Event Generation helps reduce duplication of effort and resource consumption, and benefits the whole High Energy Physics community. We give examples of use cases and user experiences, discuss financial and environmental savings, and suggest future directions.

hep-ph↗

arXiv2025

Reinterpretation and preservation of data and analyses in HEP

Data from particle physics experiments are unique and are often the result of a very large investment of resources. Given the potential scientific impact of these data, which goes far beyond the immediate priorities of the experimental collaborations that obtain them, it is imperative that the collaborations and the wider particle physics community publish and preserve sufficient information to ensure that this impact can be realised, now and into the future. The information to be published and preserved includes the algorithms, statistical information, simulations and the recorded data. This publication and preservation requires significant resources, and should be a strategic priority with commensurate planning and resource allocation from the earliest stages of future facilities and experiments.

hep-ph↗

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.

hep-ph↗

arXiv2022

A standard convention for particle-level Monte Carlo event-variation weights

Streams of event weights in particle-level Monte Carlo event generators are a convenient and immensely CPU-efficient approach to express systematic uncertainties in phenomenology calculations, providing systematic variations on the nominal prediction within a single event sample. But the lack of a common standard for labelling these variation streams across different tools has proven to be a major limitation for event-processing tools and analysers alike. Here we propose a well-defined, extensible community standard for the naming, ordering, and interpretation of weight streams that will serve as the basis for semantically correct parsing and combination of such variations in both theoretical and experimental studies.

hep-ph↗

arXiv2022

Accelerating LHC event generation with simplified pilot runs and fast PDFs

Poor computing efficiency of precision event generators for LHC physics has become a bottleneck for Monte-Carlo event simulation campaigns. We provide solutions to this problem by focusing on two major components of general-purpose event generators: The PDF evaluator and the matrix-element generator. For a typical production setup in the ATLAS experiment, we show that the two can consume about 80% of the total runtime. Using NLO simulations of $pp\to\ell^+\ell^-+\text{jets}$ and $pp\to t\bar{t}+\text{jets}$ as an example, we demonstrate that the computing footprint of LHAPDF and Sherpa can be reduced by factors of order 10, while maintaining the formal accuracy of the event sample. The improved codes are made publicly available.

hep-ph↗

arXiv2021

Four lepton production and the accuracy of QED FSR

We scrutinise the ability of the primary QED final-state resummation tools, combined with electroweak virtual corrections, to reproduce the exact next-to-leading order electroweak calculation in the four-charged-lepton final state. We further examine the dependence of the findings on the lepton-photon dressing-cone size as well as the resonance identification strategy. Overall we find excellent agreement with the fixed-order result, but partial differences not directly connected with resummation-induced higher-order effects at the few-percent level are observed in some cases, which are relevant for precision measurements.

hep-ph↗

arXiv2021

Challenges in Monte Carlo event generator software for High-Luminosity LHC

We review the main software and computing challenges for the Monte Carlo physics event generators used by the LHC experiments, in view of the High-Luminosity LHC (HL-LHC) physics programme. This paper has been prepared by the HEP Software Foundation (HSF) Physics Event Generator Working Group as an input to the LHCC review of HL-LHC computing, which has started in May 2020.

hep-ph↗

arXiv2020

HL-LHC Computing Review: Common Tools and Community Software

Common and community software packages, such as ROOT, Geant4 and event generators have been a key part of the LHC's success so far and continued development and optimisation will be critical in the future. The challenges are driven by an ambitious physics programme, notably the LHC accelerator upgrade to high-luminosity, HL-LHC, and the corresponding detector upgrades of ATLAS and CMS. In this document we address the issues for software that is used in multiple experiments (usually even more widely than ATLAS and CMS) and maintained by teams of developers who are either not linked to a particular experiment or who contribute to common software within the context of their experiment activity. We also give space to general considerations for future software and projects that tackle upcoming challenges, no matter who writes it, which is an area where community convergence on best practice is extremely useful.

physics.comp-ph↗

arXiv2019

NNLO versus NLO multi-jet merging for top-pair production including electroweak corrections

In this proceedings we compare phenomenological predictions for differential distributions in top-quark pair production at the LHC. In particular we consider NNLO QCD fixed-order predictions and parton-level predictions based on NLO QCD multi-jet merging following the MEPS@NLO scheme. In both predictions NLO electroweak (EW) corrections are incorporated in different approximations. We focus on several transverse-momentum distributions and on the top-quark invariant mass distribution, both highly relevant for the ongoing physics program at the LHC. We discuss comparisons between the different considered approximations and their advantages and disadvantages for different distributions.

hep-ph↗

arXiv2018

Multi-jet merged top-pair production including electroweak corrections

We present theoretical predictions for the production of top-quark pairs in association with jets at the LHC including electroweak (EW) corrections. First, we present and compare differential predictions at the fixed-order level for $t \bar t$ and $t \bar t+$jet production at the LHC considering the dominant NLO EW corrections of order $\mathcal{O}(α_S^2 α)$ and $\mathcal{O}(α_S^3 α)$ respectively together with all additional subleading Born and one-loop contributions. The NLO EW corrections are enhanced at large energies and in particular alter the shape of the top transverse momentum distribution, whose reliable modelling is crucial for many searches for new physics at the energy frontier. Based on the fixed-order results we motivate an approximation of the EW corrections valid at the percent level, that allows us to readily incorporate the EW corrections in the MEPS@NLO framework of Sherpa combined with OpenLoops. Subsequently, we present multi-jet merged parton-level predictions for inclusive top-pair production incorporating NLO QCD+EW corrections to $t \bar t$ and $t \bar t+$jet. Finally, we compare at the particle-level against a recent 8 TeV measurement of the top transverse momentum distribution performed by ATLAS in the lepton+jet channel. We find very good agreement between the Monte Carlo prediction and the data when the EW corrections are included.

hep-ph↗