Choose timezone
Your profile timezone:
MC4EIC 2026
→
Europe/Zurich
Y44-H-05
Winterthurerstrasse 190
8057 Zürich
Frank Martin Krauss,
Ilkka Helenius
(University of Jyväskylä),
Peter Meinzinger
(Zürich University),
Thomas Kurt Gehrmann
(University of Zurich (CH))
Description
The 2026 edition of the MC4EIC workshop on Monte Carlo event generation for the EIC will take place at the University of Zurich.
The primary focus of this workshop is to discuss the status of event generators for the Electron-Ion Collider and the related experimental needs.
Topics to be covered:
- General-purpose event generators for DIS, photoproduction, and diffractive processes
- Comparisons and tuning to relevant ep and ed data
- Protons to Ions: Challenges, Solutions, etc.
- Experimental needs: a wishlist
- Lessons from the LHC
- Specialized event generators and interfacing
Please register for the workshop to receive updates on the program and organizational details.
A registration fee of CHF200 will be charged for the workshop. It will need to be paid by card at the beginning of the workshop.
Participants
-
-
Experiments
- 2
-
3
Probing nuclear parton distributions with Ultra-peripheral photonuclear collisions at the LHC
Ultra-peripheral heavy ion collisions occur in ultra-relativistic nuclear scatterings with impact parameters larger than the sum of the nuclear radii. In these collisions, the hadronic interactions between the nuclei are highly suppressed and the scatterings involve energetic photons emitted by one or both nuclei. At the LHC the photon fluxes are sufficiently large at high energies to provide measurable rates of photon-induced hard scattering processes on nuclei with dijet and multi-jet final states. In these photonuclear collisions, the measured jet transverse momenta and rapidities provide direct information on the hard-scattering kinematics, especially xA — the Bjorken x of the parton from the lead nucleus – and the Q2 of the process. ATLAS has published results for both inclusive photonuclear jet production and jet production in photon-lead collisions with no forward neutron emission. The former should provide strong constraints on the complete nuclear
parton distributions in the lead nucleus, while the latter measurement probes the parton distribution in the periphery of the lead nucleus. That measurement has demonstrated that the nuclear parton distributions in the periphery are significantly different from the impact parameter- or radius-integrated parton distributions. Thus, it provides the first direct empirical evidence for impact parameter or radius-dependence of nuclear PDFs. The inclusive photonuclear measurements from the LHC are both complementary to future DIS and photonuclear measurements and will help constrain nuclear PDFs prior to the start of EIC operations. Simlarly, current and future photonuclear measurements at the LHC selecting on final-state characteristics such as forward neutron production may provide novel physics opportunities that can be explored with more precision at the EIC using forward detectors.Speaker: Brian Andrew Cole (Columbia University (US))
-
15:00
Coffee and tea
-
General purpose MCs
-
4
Recent Developments in Herwig 7
This talk will present a brief overview of recent developments in the Herwig 7 Monte Carlo event generator, focusing on improvements related to parton showers and hadronization. The main focus will be a new next-to-leading-order treatment of polarized deep inelastic scattering that includes spin correlations in the parton shower. I will show how these effects can influence predictions at Electron-Ion Collider energies.
Speaker: Andreas Papaefstathiou (Kennesaw State University (US)) - 5
- 6
-
7
MadGraph7: Hardware-Accelerated Monte Carlo Event Generation for the HL-LHC Era
The High-Luminosity LHC (HL-LHC) upgrade presents new challenges to the computing infrastructure of the LHC experiments. Monte Carlo event generation is projected to account for 10–20% of total CPU usage at ATLAS and CMS, making the speed-ups of these tools a more pressing requirement.
MadGraph7, the next major release of the MadGraph5_aMC@NLO framework, addresses this challenge via a complete redesign of the event-generation pipeline with hardware acceleration in mind, including several algorithmic improvements to offload calculations on both GPUs and CPUs with vector instructions, that are increasingly populating HPC sites and grid resources.
Three new developments will be integrated in MadGraph7: MadMatrix, MadSpace, and AmpliCol. MadMatrix and MadSpace are related to the hardware acceleration of the matrix element computation and the phase space, respectively, while AmpliCol provides an optimised algorithm to deal with high multiplicity amplitudes.
This talk presents their main features and how they combine to create a generation framework ready for the computational demands of the HL-LHC.Speaker: Daniele Massaro (CERN)
-
4
-
-
Matrix element generators
- 8
-
9
Photoproduction in MadGraph5\_aMC@NLO
MadGraph5_aMC@NLO is a widely used general-purpose event generator whose NLO framework has until now been restricted to symmetric hadronic collisions. With the Electron-Ion Collider era approaching, we present an implementation of direct photoproduction at NLO, as well as an asymmetric collision framework that enables resolved photoproduction at NLO. We present results for single and double heavy-quark-pair photoproduction at EIC and LHeC energies, including the first NLO predictions for processes such as γp→bbˉbbˉ and γp→bbˉccˉ in a general-purpose tool.
Speaker: Allen Cris John Rubesh Rajan (University College Dublin) -
10
Event generation of dijet photoproduction in POWHEG-BOX
Photon-induced processes will be a key production mechanism at the approved EIC. With this
renewed interest, the demand for precise predictions from state-of-the-art Monte Carlo
generators has increased. In this talk, I will present recent efforts to develop a POWHEG-BOX
extension for simulating photoproduced dijets, including both direct and resolved photon
contributions based on the Weizsäcker-Williams Approximation. This implementation will enable
event generation at NLO+PS accuracy for collisions involving leptons, protons, and heavy ions.
It is particularly relevant for EIC studies and is also applicable to ultra-peripheral
collisions (UPCs) at the LHC.Speaker: Alexander Feike
-
10:30
Coffee and tea
-
Polarization: Polarization and parton showers
-
11
Polarized hadronization
The string+3P0 model is an extension of the Lund string Model that includes the quark spin degree of freedom at the amplitude level and is capable of reproducing spin effects in hadronization such as the Collins effect and the dihadron asymmetries. It is interfaced to the Pythia event generator via the StringSpinner package for deep inelastic scattering (DIS) and e+e- annihilation to hadrons. In this talk we review the status of the string+3P0 model as well as the results obtained with StringSpinner on transverse spin effects in DIS and e+e- annihilation.
Speakers: Albi Kerbizi (Universita e INFN Trieste (IT)), Albi Kerbizi -
12
Parton-shower effects in polarized deep inelastic scattering
We present a Monte-Carlo program for the simulation of polarized deep inelastic scattering at next-to-leading order in QCD matched to parton shower programs building on an existing implementation of the unpolarized case in the POWHEG BOX package. We discuss extensions of the POWHEG BOX framework necessary to account for polarized initial states and validate the code by detailed comparisons to existing fixed-order results. We then use the new tool to make predictions for the upcoming Electron Ion Collider. We find that parton-shower effects do have an impact on experimentally accessible distributions and improve the agreement with the next-to-next-to-leading order results.
Speaker: Ignacio Borsa -
13
NLO Matching and Apollo shower in Pythia
I will review recent work in Pythia relating to higher-order corrections and logarithmically accurate parton showers in Pythia. On the one hand, I will present a new fully-internal multiplicative NLO matching for DIS processes, which has been applied to both the Pythia simple shower with dipole recoil and the Vincia antenna shower. On the other hand, I will discuss progress on the Apollo parton-shower framework, which aims to simulate parton showers with higher-logarithmic accuracy. I will close by relating the two approaches and give an outlook on future extensions in the context of DIS processes.
Speaker: Christian Preuss (University of Goettingen)
-
11
-
12:30
Lunch
-
Photon structure
-
14
VALO1.0: New parton distributions of the real photon
Precise determination of the partonic structure of real photons has attracted renewed interest in view of ongoing studies of high-energy photon-induced processes in ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) and at the future Electron-Ion Collider (EIC).
Despite being fundamental in their own right and essential for QCD phenomenology of hard processes initiated by resolved photons, the quark and gluon distributions of the photon are poorly known and merit a new analysis employing modern tools of statistical data analysis.We determine new sets of leading order (LO) and next-to-leading order (NLO) parton distributions (PDFs) of the real photon by performing a global QCD analysis of the world data on the photon structure function $F_2^{\gamma}(x,Q^2)$ measured in deep-inelastic scattering (DIS) processes on a real photon target in electron-positron collisions.
Our analysis improves on the results available in the literature by providing uncertainties in the form of Monte-Carlo replicas and PDFs in the LHAPDF6 format.
While electron-positron data determines the singlet quark distribution very well at both LO and NLO, the gluon distribution is constrained to a much lesser degree, especially at LO.
For this analysis, we have developed an open-source framework, which extends the \href{https://nnpdf.github.io/pineline/}{pineline} framework to the photon case and includes the program solving the inhomogeneous $Q^2$ evolution of photon PDFs, \href{https://geko.readthedocs.io/en/latest/}{$\gamma$EKO}.Speaker: Madhav Chithirasreemadam -
15
Resolved-photon PDFs from particle-level event-generator tuning
We present our progress towards a new determination of resolved-photon parton distribution functions using particle-level event-generator tuning techniques. We use Sherpa, Rivet and Professor to fit photon PDFs directly to HERA and LEP measurements, using PDF reweighting to sample the parameter space while retaining full PS and hadronisation effects. Since our previous presentations, the framework has been extended with a dedicated underlying-event tune for resolved-photon processes, reducing the risk of absorbing multiparton-interaction effects into the fitted PDFs. We also present results obtained using photon PDFs defined in the MS_bar factorisation scheme, for use with MC generators. The status of the PDF fits, uncertainty estimation, and validation against photoproduction observables will be discussed.
Speaker: Vithyaban Anjelo Narendran (University of Oxford (GB)) -
16
Diffractive dijets in General purpose MCsSpeaker: Peter Meinzinger (Zürich University)
-
14
-
15:00
Coffee and tea
-
Selected topics: Diffraction
-
17
Diffractive deep inelastic scattering in Pythia
At HERA energies ($E_{CM}\approx 320$ GeV), around ten per cent of events in electron-proton collisions are of diffractive nature. Inspired by Regge theory and the Ingelman-Schlein picture, diffractive events in Pythia are modeled via a pomeron exchange, which is treated as a particle with a parton distribution function (PDF). The diffractive part of the PDF is given by a convolution of the pomeron flux and the pomeron PDF, which have been measured at HERA. Diffractive events in electron-proton collisions can already be modeled by using a photon flux from the electron in Pythia. We can extend this to events with finite virtuality, which can be described as diffractive deep inelastic scattering (DIS). The difference to inclusive DIS is, that the parton for the hard interaction is now taken from a pomeron, which is taken from a proton, leaving the proton intact and elastically scattered.
Using just the $2\rightarrow 2$ leading order matrix elements and parton showers, the results undershoot the measured jet production cross sections by a large margin. As parton showers are constructed to reproduce the soft and collinear limits, they struggle to describe hard jet production. Data description can be significantly improved by using merging algorithms, where the standard parton shower is merged with $2 \rightarrow 3$ and higher multiplicity matrix elements.
We will present a new setup for diffractive DIS in Pythia with multi-parton merging and improved sampling for pomeron kinematics. The results are analyzed and compared to the HERA data with the rivet analysis H1_2015_I1343110.
Speaker: Constantina Sporleder (University of Jyvaskyla (FI))
-
17
-
Validation and tuning
-
18
A HERA-Constrained Hadronisation Tune for EIC Applications
Precise modelling of hadronisation remains an important source of uncertainty in event-generator predictions for the future Electron-Ion Collider (EIC). While existing hadronisation tunes are largely constrained by LEP data, HERA measurements provide complementary information from electron–proton collisions in a kinematic regime more closely related to that of the EIC.
We present recent developments towards a HERA-constrained hadronisation tune using the Rivet and Professor frameworks. As part of this effort, approximately ten HERA measurements have been newly implemented in Rivet and incorporated into a tuning workflow. In parallel, several improvements have been made to the Professor tuning framework, including uncertainty-aware filtering of tuning observables and more efficient sampling strategies for high-dimensional parameter spaces.
Following validation of the workflow through reproduction of an existing Sherpa LEP tune, we present a first hadronisation tune incorporating the new HERA constraints. We discuss the impact of the HERA measurements on the tuned parameter values and assess their potential role in improving event-generator descriptions for future EIC studies.
Speaker: Vithyaban Anjelo Narendran (University of Oxford (GB)) - 19
-
18
-
19:00
Dinner
-
-
-
Exclusive processes and nuclear targets
-
20
Particle Production in Nuclear DIS with BeAGLE++
BeAGLE (Benchmark eA Generator for Leptoproduction) is the primary event generator currently used to simulate deep inelastic scattering on nuclei (eA) for the upcoming Electron-Ion Collider (EIC) in the United States. It plays a central role in improving our understanding of key nuclear physics processes, informing detector design, and defining the integration requirements for the interaction regions. As the main simulation tool used by the ePIC collaboration, BeAGLE is expected to be central to both the physics case and the engineering of the second interaction region. However, its legacy FORTRAN codebase poses major challenges for modern development, extensibility, and long-term maintenance. To address these limitations, we have begun a full rewrite of BeAGLE in C++, leading to BeAGLE++, a modern, modular, and extensible event generator built to support the evolving needs of the EIC physics program.
In this talk, I will present the first release of BeAGLE++, highlighting its improved architecture and expanded physics capabilities. Special emphasis will be placed on simulations of particle production in the target fragmentation region, which provide a sensitive probe of final-state interactions and nuclear effects. BeAGLE++ will play an essential role in precision simulations, systematic studies, and data analysis workflows, offering the community a robust and sustainable tool ahead of EIC operations and representing a significant step forward in lepton-nucleus collision modeling.
Speaker: Arjun Kumar -
21
New developments in the Sartre event generator
I report on three major new developments in the Sartre event generator.
1. Sartre calculates coherent and incoherent cross sections in the dipole model for diffractive DIS by taking the first and second moment of the interaction dipole amplitude with respect to initial geometric configurations. As this is an extremely CPU heavy task, we tabulate these moments on file, and these lookup tables can then be used for efficient event generation. These lookup tables are 3-dimensional in Q2, W2, and t. We have recently developed a new method for calculating the amplitude for the lookup tables utilizing discreet Fourier transform. This reduces the dimensionality of the lookup tables from 3D to 2D. Together with other optimizations in the integration, the increased efficiency in the table production has improved by 3 orders of magnitude, enabling a much more versatile event generator for the EIC and the LHeC, reducing the practical production time of new tables from weeks or months to hours.
2. We have implemented inclusive diffraction into Sartre, making it the first event generator for heavy ion inclusive diffraction at small x.
3. We now have a dedicated ultra-peripheral collisions version of Sartre to be used for UPC studies at RHIC and the LHC.Speaker: Tobias Toll -
22
Road to TMD MCsSpeakers: Andrea Signori (University of Turin and INFN), Andrea Signori (University of Pavia and Jefferson Lab)
-
20
-
11:00
Coffee and tea
-
Selected topics: Massive quark and photon production
-
23
Neutrino DIS with massive final states
The large flux of forward neutrinos produced in proton-proton collisions
at the LHC constitutes a unique opportunity for new studies in neutrino physics,
also including tau neutrino interactions.
The recent SND@LHC and FASER experiments at the LHC will enable
these studies by exploiting this unprecedented flux of high-energy neutrinos.
Deep Inelastic Scattering (DIS) processes provide the natural
framework to perform these studies.
To this end, an event generator for DIS has been developed, exploiting the POWHEG
method to match fixed-order NLO QCD corrections to Shower Monte Carlo programs.
The code provides fully differential predictions at NLO+PS accuracy
for neutral current and charged current DIS processes, including
incoming tau neutrinos and final states with charm quarks.Speaker: Giovanni Limatola -
24
Heavy-quark pair-production in DIS at NLO QCD matched to a parton shower
We present theoretical predictions for heavy-quark pair production in deep-inelastic scattering at NLO in QCD, matched to parton-shower evolution within the POWHEG framework. We revisit the NLO amplitude calculation and implement a consistent matching procedure, with careful treatment of heavy-quark mass effects and the avoidance of double counting between fixed-order and parton-shower radiation. In addition, we compare the virtual NLO corrections available in the literature with one-loop amplitudes obtained through massification in the small-mass limit. These results are relevant for precision studies of heavy-flavour production at the future Electron-Ion Collider.
Speaker: Santiago Castro -
25
Photon Fragmentation Functions extracted from Pythia stored in LHAPDF
Prompt-photon predictions with experimentally relevant isolation criteria retain a residual dependence on parton-to-photon fragmentation functions, whose phenomenological uncertainties remain only weakly constrained.
We present a pragmatic study of photon fragmentation functions extracted from Pythia parton-shower events and stored in an LHAPDF-compatible format.
We briefly review the role of photon fragmentation in perturbative QCD and then construct shower-level estimates of the flavour-dependent functions (D_{\gamma/i}(z,\mu_D)) as functions of the photon momentum fraction (z) and fragmentation scale (\mu_D).
The extracted distributions show the expected qualitative hierarchy between quark and gluon channels and an increasing fragmentation probability with scale.Speaker: Alexander Puck Neuwirth (UNIMIB & INFN)
-
23
-
13:00
Lunch
-