Skip to main content

Training Network for Monte Carlo Event Generators for LHC Physics

Final Report Summary - MCNETITN (Training Network for Monte Carlo Event Generators for LHC Physics)

MCnetITN was a European Union funded Marie Curie Initial Training Network dedicated to developing and supporting general-purpose Monte Carlo event generators throughout the LHC era and beyond, and providing training of a wide selection of its user base, particularly through funded short-term 'residencies' and Annual Schools. It ran from January 2013 to December 2016 and its legacy will be continued by a new network, MCnetITN3, from April 2017.

Monte Carlo event generators are central to high energy particle physics. They are used by almost all experimental collaborations to plan their experiments and analyze their data, and by theorists to simulate the complex final states of the fundamental interactions that may signal new physics. The network incorporates all the authors of current general purpose event generators.

The main purposes of MCnetITN were to:
• train a large section of our user base, using annual schools on the physics and techniques of event generators and short-term residencies of Early Stage Researchers as a conduit for transfer of knowledge to the wider community;
• train the next generation of event generator authors through a significant number of dedicated studentships in our research groups;
• provide broader training in transferable skills through our research, through dedicated training in entrepreneurship, employability and outreach and through secondments to private sector partners.

These training objectives have been achieved both through dedicated activities and through our outreach and research activities:
• enhancing the visibility of particle physics in the wider community by specific outreach projects using event generators to visualize current particle physics research;
• developing and supporting the new generation of event generators intended for use throughout the LHC data analysis era and beyond;
• playing a central role in the analysis of LHC data and the discovery of new particles and interactions there; and
• extracting the maximum potential from existing data to constrain the modeling of the data from the LHC and future experiments.

The impact of MCnetITN extends beyond the field of event generator physics and techniques, to experimental particle physics, the main user of this research. The improved event generators provided by MCnetITN will enable better exploitation of LHC data, better-quantified sensitivity to new physics, better measurements of Higgs boson and other Standard Model physics parameters, and ultimately perhaps even the parameters of any new physics scenarios that are discovered.

The final two years of MCnetITN have seen great progress in our main research projects on the Monte Carlo event generators, Pythia, Herwig, Sherpa, Madgraph and Ariadne and our cross-cutting project to develop generator-related tools, CEDAR, and in achieving the objectives of the network.

The primary focus of our work is in the confrontation of theoretical predictions with the experimental data from the LHC. This had considerable impact on the discovery of the Higgs Boson at LHC and contributed to our basic understanding about mass generation in the Standard Model. The algorithms developed and refined by MCnetITN members were used extensively by the two experiments that discovered the Higgs boson (ATLAS, CMS) to evaluate both the backgrounds to Higgs particle production and the detector response to the signal. With the higher energy and intensity running of the LHC in the last two years, detailed measurements of the Higgs boson and other Standard Model particles have been the priority, as well as the search for new particles. Our simulations are an essential part of these measurements and searches, enabling the LHC’s headline achievements.

On the more theoretical front, we have largely achieved our long-term goal of automated next-to-leading order (NLO) multi-jet matching and have been turning our attention to NNLO algorithms. This has also driven a deeper understanding of the connection between our parton shower based approaches and other approaches to high-order QCD calculations.

The take-up and use of the CEDAR Rivet framework by the experimental community is another important product of the network. This encapsulates the results of experimental analyses in a form in which they can be compared with event generators or theoretical models in perpetuity. Together with the Professor framework for tuning event generator parameters, this has a major impact on the accuracy of simulation that can be offered to the experimental community, since new versions can be released already tuned and calibrated on the collection of all previous data. Through this project we have also had a direct impact on the culture of data preservation in the LHC experiments. A new CEDAR project, LHAPDF6, has also had a major impact on encapsulation and use of results from the LHC and earlier experiments that constrain our understanding of proton structure, a crucial input to all simulations and calculations for the LHC and predictions for future experiments.

Many of the successes of our individual projects involved elements of inter-project collaboration. Of particular note is the publication of the "Update of the Binoth Les Houches Accord for a standard interface between Monte Carlo tools and one-loop programs". This is the result of inter-project activity spearheaded by members of MCnetITN and includes authors of all of our event generator projects. It has had a direct impact on the reach of all of our programs. In addition, members of all of our projects have collaborated on contributions to the many workshops that summarize and co-ordinate theoretical input to the experimental programme. In particular, we have played major roles in the ongoing Higgs cross section working group, essential for all Higgs measurements at the LHC, the international workshop on physics at future colliders and have convened many of the working groups at the biennial Les Houches workshops on “Physics at TeV Colliders”.

Working at the interface of particle theory and experiment the 14 MCnetITN long-term Early Stage Researchers have gained experience of collaborative working, technical and management skills. The result is a skill set that is highly valued in both the academic world and the private sector, and can be applied in the field of event generator physics and in other areas of science and the private sector.

34 short-term ESRs have come into our groups as part of their PhDs elsewhere, for periods of only a few months, but the training they receive has an impact throughout the rest of their PhDs, and beyond. 170 external students have also been trained in our Annual Schools. 4 ESRs have gained invaluable transferrable skills through studentships in our private-sector partner organizations and on our physics outreach project, LHC@home.

MCnetITN allows members to exchange and promote best practice in PhD supervision, students have a great degree of internal mobility to experience working in other research groups and projects, and the network enables Monte Carlo Schools to be rolled out annually, and on demand externally. As a result the network will have a lasting effect in creating this collaborative approach to training and promoting the exchange and sharing of knowledge.

Further information about MCnetITN is available from: