arXiv subjects

Jon Butterworth

Publications and source records attributed to Jon Butterworth.

At least 19 recordsLinked to original sources

arXiv2026

The Plan B Model: $Z^{\prime}$ collider phenomenology and discovery prospects

The Plan B Model was proposed by Allanach et al. (2023) and explains some gross features of the fermion mass spectrum. It also affects the predictions of various observables involving the $b \rightarrow s$ quark-flavour transition. The model predicts a new TeV-scale $Z^{\prime}$ which decays into various different final states. We constrain the viable parameter space of the model by re-casting several LHC direct searches for the $Z^{\prime}$ in addition to using Contur to test the model against unfolded measurements of various differential cross sections that are predicted to be non-zero in the Standard Model. We delineate the regions of parameter space that are excluded by current LHC data, and estimate the projected reach of the high luminosity LHC.

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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.

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arXiv2025

Global fits and the search for new physics: past, present and future

In this work, we review the history and current role of global fits in the search for physics beyond the Standard Model~(BSM), including precision tests of the Standard Model (SM). Although BSM global fits were initially focused on minimal supersymmetric models, we describe how fits have evolved in response to new data from the Large Hadron Collider (LHC) and elsewhere, expanding to encompass a broad spectrum of BSM scenarios including non-minimal supersymmetry, axion-like particles, extended Higgs sectors, dark matter models, and effective field theories such as SMEFT. We discuss how the role of global fits has shifted from forecasting possible signals of new physics at the LHC to understanding the impact of null results from LHC run-I and II and the discovery of the Higgs boson, and how interest has shifted from global fits for parameter estimation to comprehensive model comparison. We close by discussing potential trends and future applications, emphasizing the potential for machine learning and artificial intelligence to enhance the efficiency of sampling algorithms and comparison between theory and experiment, as well as collaboration and software development.

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arXiv2025

Quark-Lepton Unification Signatures

We investigate the collider signatures of the minimal framework for quark-lepton unification at a scale not far from the electroweak symmetry breaking scale. This theory predicts a rich spectrum of new fields, including one vector leptoquark, two scalar leptoquarks, a color-octet scalar, and an additional Higgs doublet. Neutrino masses are generated via the inverse seesaw mechanism, facilitating viable matter unification at the low scale. We find that this theory predicts that in many cases the dominant leptoquark decays are to the third generation Standard Model quarks and leptons. We identify key experimental signatures at the Large Hadron Collider, evaluate and discuss the limits from current measurements, and outline potential strategies for probing this theory in the near future.

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arXiv2025

Probing the coupling of axions to tops and gluons with LHC measurements

We study axion-like particles (ALPs) whose dominant interactions are with gluons and third-generation quarks, and whose couplings to light Standard Model (SM) particles arise at one loop. These loop-induced effects lead to ALP decays and production channels that can be probed at the LHC, even when tree-level couplings are absent. Using an effective field theory (EFT) description that includes momentum-dependent corrections from radiative effects, we reinterpret a wide range of LHC measurements via the CONTUR framework to derive model-independent constraints on the ALP parameter space. We show that LHC data place meaningful bounds in the plane of effective couplings $c^0_t/f_a$ and $c^0_{\tilde G}/f_a$, and that these limits are sensitive to the UV origin of the ALP-top and ALP-gluon couplings. We discuss representative scenarios where either $c^0_t$ or $c^0_{\tilde G}$ vanishes at the matching scale, and highlight the role of EFT running and mixing in generating observable signals. We also assess the domain of validity of the EFT approach by comparing the typical momentum transfer $\sqrt{\hat s}$ in sensitive regions to the underlying scale $f_a$. Our results demonstrate the power of loop-aware EFT reinterpretation of SM measurements in probing otherwise elusive ALP scenarios. The framework presented here can be readily extended to include couplings to other fermions and to accommodate ALP decay or long-lived signatures.

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arXiv2025

Constraints On New Theories Using Rivet : CONTUR version 3 release note

The CONTUR toolkit exploits RIVET and its library of more than a thousand energy-frontier differential cross-section measurements from the Large Hadron Collider to allow rapid limit-setting and consistency checks for new physics models. In this note we summarise the main changes in the new CONTUR 3 major release series. These include additional statistical treatments, efficiency improvements, new plotting utilities and many new measurements and Standard Model predictions.

hep-ph↗

arXiv2025

Local Baryon Number at the LHC

The minimal theory in which baryon number is spontaneously broken at the low scale predicts new fermions, one of which is a dark matter candidate, from gauge anomaly cancellation. We discuss the production mechanisms and decays of these new fermions, which include channels with multi-leptons, and channels with long-lived charged fermions that can give rise to exotic signatures with 'kinked' tracks at the Large Hadron Collider. We evaluate the contraints on the theory from current LHC searches and measurements, and briefly comment on the excess in top pair production at threshold recently reported by CMS. We also discuss predictions for the $h \to \gamma Z_B$ decay, where $h$ is the SM-like Higgs and $Z_B$ is the new gauge boson associated with baryon number.

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↗

arXiv2025

Probing the sensitivity of semi-visible jets to current LHC measurements using the CONTUR toolkit

Semi-visible jets arise from a hypothetical, strongly interacting ``dark sector'' -- a dark counterpart of quantum chromodynamics whose partial decays back to Standard Model particles introduce new types of collider BSM signature. CMS and ATLAS have have searched for semi-visible jets in the resonant and non-resonant production modes and set constraints on mediator mass values. In this work, indirect constraints on various model parameters, such as dark hadron masses and coupling strengths, are explored using LHC measurements.

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arXiv2024

Dark Matter from Anomaly Cancellation at the LHC

We discuss a class of theories that predict a fermionic dark matter candidate from gauge anomaly cancellation. As an explicit example, we study the predictions in theories where the global symmetry associated with baryon number is promoted to a local gauge symmetry. In this context the symmetry-breaking scale has to be below the multi-TeV scale in order to be in agreement with the cosmological constraints on the dark matter relic density. The new physical "Cucuyo" Higgs boson in the theory has very interesting properties, decaying mainly into two photons in the low mass region, and mainly into dark matter in the intermediate mass region. We study the most important signatures at the Large Hadron Collider, evaluating the experimental bounds. We discuss the correlation between the dark matter relic density, direct detection and collider constraints. We find that these theories are still viable, and are susceptible to being probed in current, and future high-luminosity, running.

hep-ph↗

arXiv2023

Custodial Symmetry Breaking and Higgs Signatures at the LHC

We discuss the simplest model that predicts a tree level modification of the $\rho$ parameter from a shift in the $W$-mass without changing the prediction for the $Z$ mass. This model predicts a new neutral Higgs and two charged Higgses, with very similar masses and suppressed couplings to the Standard Model fermions. We discuss the decay properties of these new scalar bosons, and the main signatures at the Large Hadron Collider. Comparing these signatures for the first time to the latest measurements, we show that while masses around 200 GeV are excluded for some scenarios, over a wide range of model parameter space the new bosons can have a mass close to the electroweak scale without violating existing limits from experimental searches or destroying the agreement with measurements. We investigate the scenario where the new neutral Higgs is fermiophobic and has a large branching ratio into $W$ gauge bosons and/or photons, and show that this could lead to a signal in the diphoton mass spectrum at low Higgs masses. We discuss the different signatures that can motivate new measurements and searches at the Large Hadron Collider.

hep-ph↗

arXiv2023

Testing the Scalar Triplet Solution to CDF's Fat $W$ Problem at the LHC

The Type II Seesaw model remains a popular and viable explanation of neutrino masses and mixing angles. By hypothesizing the existence of a scalar that is a triplet under the weak gauge interaction, the model predicts strong correlations among neutrino oscillation parameters, signals at lepton flavor experiments, and collider observables at high energies. We investigate reports that the Type II Seesaw can naturally accommodate recent measurements by the CDF collaboration, which finds the mass of the $W$ boson to be significantly larger than allowed by electroweak precision data, while simultaneously evading constraints from direct searches. Experimental scrutiny of this parameter space in the Type II Seesaw has long been evaded since it is not characterized by ``golden channels'' at colliders but instead by cascade decays, moderate mass splittings, and many soft final states. In this work, we test this parameter space against publicly released measurements made at the Large Hadron Collider. By employing a newly developed tool chain combining MadGraph5\_aMC@NLO and Contur, we find that most of the favored space for this discrepancy is already excluded by measurements of Standard Model final states. We give suggestions for further exploration at Run III of the LHC, which is now underway.

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arXiv2022

Picking the low-hanging fruit: testing new physics at scale with active learning

Since the discovery of the Higgs boson, testing the many possible extensions to the Standard Model has become a key challenge in particle physics. This paper discusses a new method for predicting the compatibility of new physics theories with existing experimental data from particle colliders. Using machine learning, the technique obtained comparable results to previous methods (>90% precision and recall) with only a fraction of their computing resources (<10%). This makes it possible to test models that were impossible to probe before, and allows for large-scale testing of new physics theories.

hep-ph↗

arXiv2022

The PDF4LHC21 combination of global PDF fits for the LHC Run III

A precise knowledge of the quark and gluon structure of the proton, encoded by the parton distribution functions (PDFs), is of paramount importance for the interpretation of high-energy processes at present and future lepton-hadron and hadron-hadron colliders. Motivated by recent progress in the PDF determinations carried out by the CT, MSHT, and NNPDF groups, we present an updated combination of global PDF fits: PDF4LHC21. It is based on the Monte Carlo combination of the CT18, MSHT20, and NNPDF3.1 sets followed by either its Hessian reduction or its replica compression. Extensive benchmark studies are carried out in order to disentangle the origin of the differences between the three global PDF sets. In particular, dedicated fits based on almost identical theory settings and input datasets are performed by the three groups, highlighting the role played by the respective fitting methodologies. We compare the new PDF4LHC21 combination with its predecessor, PDF4LHC15, demonstrating their good overall consistency and a modest reduction of PDF uncertainties for key LHC processes such as electroweak gauge boson production and Higgs boson production in gluon fusion. We study the phenomenological implications of PDF4LHC21 for a representative selection of inclusive, fiducial, and differential cross sections at the LHC. The PDF4LHC21 combination is made available via the LHAPDF library and provides a robust, user-friendly, and efficient method to estimate the PDF uncertainties associated to theoretical calculations for the upcoming Run III of the LHC and beyond.

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arXiv2022

Data and Analysis Preservation, Recasting, and Reinterpretation

We make the case for the systematic, reliable preservation of event-wise data, derived data products, and executable analysis code. This preservation enables the analyses' long-term future reuse, in order to maximise the scientific impact of publicly funded particle-physics experiments. We cover the needs of both the experimental and theoretical particle physics communities, and outline the goals and benefits that are uniquely enabled by analysis recasting and reinterpretation. We also discuss technical challenges and infrastructure needs, as well as sociological challenges and changes, and give summary recommendations to the particle-physics community.

hep-ph↗

arXiv2019

Highlights of EPS HEP 2019

An opinionated and informal recap of highlights from the EPS HEP 2019 conference in Ghent, including some aspects of flavour physics, neutrinos, high-density QCD, astrophysics and energy frontier collider physics, and some thoughts about the future.

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arXiv2019

Monte Carlo event generators for high energy particle physics event simulation

Monte Carlo event generators (MCEGs) are the indispensable workhorses of particle physics, bridging the gap between theoretical ideas and first-principles calculations on the one hand, and the complex detector signatures and data of the experimental community on the other hand. All collider physics experiments are dependent on simulated events by MCEG codes such as Herwig, Pythia, Sherpa, POWHEG, and MG5_aMC@NLO to design and tune their detectors and analysis strategies. The development of MCEGs is overwhelmingly driven by a vibrant community of academics at European Universities, who also train the next generations of particle phenomenologists. The new challenges posed by possible future collider-based experiments and the fact that the first analyses at Run II of the LHC are now frequently limited by theory uncertainties urge the community to invest into further theoretical and technical improvements of these essential tools. In this short contribution to the European Strategy Update, we briefly review the state of the art, and the further developments that will be needed to meet the challenges of the next generation.

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arXiv2016

The Standard Model: How far can it go and how can we tell?

The Standard Model of particle physics encapsulates our current best understanding of physics at the smallest distances and highest energies. It incorporates Quantum Electrodynamics (the quantised version of Maxwell's electromagnetism) and the weak and strong interactions, and has survived unmodified for decades, save for the inclusion of non-zero neutrino masses after the observation of neutrino oscillations in the late 1990s. It describes a vast array of data over a wide range of energy scales. I review a selection of these successes, including the remarkably successful prediction of a new scalar boson, a qualitatively new kind of object observed in 2012 at the Large Hadron Collider. New calculational techniques and experimental advances challenge the Standard Model across an ever-wider range of phenomena, now extending significantly above the electroweak symmetry breaking scale. I will outline some of the consequences of these new challenges, and briefly discuss what is still to be found.

hep-ex↗