Project
High-precision cross section predictions for the Large Hadron Collider
The project is based on several projects of the Principal Investigator within the Collaborative
Research Center TRR 257 “Particie Physics Phenomenology after the Higgs Discovery” and the Research Training Group RTG 2497 “Physics of the Heaviest Particles at the Large Hadron Collider”. Both initiatives are funded by the German Research Foundation (DFG). The line of research concerns predictions for processes as observed at the Large Hadron Collider, a particle accelerator situated at CERN near Geneva. The main goal of the experiment is the elucidation of the mysteries of nature such as the constitution of Dark Matter or the origin of the asymmetry between matter and anti-matter. The current project aims at providing particle production rates. These rates are compared to measurement data in an attempt to discover discrepancies which could then be explained by proposed new phenomena.
Project Details
Project term
October 1, 2023–September 30, 2024
Affiliations
RWTH Aachen University
Institute
Institute for Theoretical Particle Physics and Cosmology
Principal Investigator
Methods
The theoretical predictions are obtained using the principles of Quantum Field Theory. In practice, this requires the generation of particle configurations according to well defined probability distributions. The problem is best solved with Monte Carlo methods. However, the complexity of the distributions requires very high statistics that can only be obtained using computer clusters. A severe problem that is being solved within this project is the treatment of singular probability distributions as predicted by Quantum Field Theory. The Principal Investigator has developed, together with collaborators, a complex software system that can handle this problem for a class of physical processes. However, new methods still need to be developed. Furthermore, we have discovered convergence issues that still remain unsolved and which have delayed to completion of one of our flagship computations.
Results
Despite some setbacks, several important results have been obtained and published in world-class specialised journals. In Ref. [1], we have performed a computation of jet rates in direct collaboration with an experiment group. This has allowed for the determination of the strength of strong interactions at the highest energies ever achieved. In Ref. [2], we have performed a study of the production of single photons in association with two resolved jets. This study was the first to take into account the complete effect of colour exchanges between virtual particles involved. In Ref. [3,4], we have obtained the long sought effects of top- and bottom-quark masses on the Higgs boson production rates. Our results remove one of the main sources of remaining theoretical uncertainties in Higgs physics. None of these results could have been obtained without the computer resources provided by NHR4CES.
Discussion
The next year of the project should allow us to finally obtain state-of-the-art results for the production of photon pairs at the Large Hadron Collider. Until now, we were only able to perform tests which led to the discovery of an issue in our methodology. The problem is still being analysed and is expected to be resolved before the fall of 2024. At that point we should be able to begin with the main runs that require the originally
assigned compute resources in the 4mio CPUh ball park.
Additional Project Information
DFG classification: 309 Particles, Nuclei and Fields
Software: The C++ library STRIPPER
Cluster: CLAIX
Publications
1. M. Alvarez, J. Cantero, M. Czakon, J. Llorente, A. Mitov and R. Poncelet
“NNLO QCD corrections to event shapes at the LHC”
JHEP 03 (2023), 129
https://doi.org/10.1007/JHEP03(2023)129
2. S. Badger, M. Czakon, H. B. Hartanto, R. Moodie, T. Peraro, R. Poncelet and S. Zoia
“Isolated photon production in association with a jet pair through next-to-nextto-
leading order in QCD”
JHEP 10 (2023), 071
https://doi.org/10.1007/JHEP10(2023)071
3. M. Czakon, F. Eschment, M. Niggetiedt, R. Poncelet and T. Schellenberger
“Top-Bottom Interference Contribution to Fully Inclusive Higgs Production”
Phys. Rev. Lett. 132 (2024) no.21, 211902
https://doi.org/10.1103/PhysRevLett.132.211902
4. M. Czakon, F. Eschment, M. Niggetiedt, R. Poncelet and T. Schellenberger
“Quark Mass Effects in Higgs Production,”
https://arxiv.org/abs/2407.12413