Project
High-precision cross section predictions for the Large Hadron Collider
The project concerns cross section predictions for the Large Hadron Collider at CERN. These predictions are required to verify whether the measurements are in agreement with the fundamental theory of elementary particles. If discrepancies would be found, it could become possible to answer some of the fundamental questions of the field as for example: what is dark matter made of? There is number of cross sections that are particularly interesting. The ultimate goal of the project are predictions for the production of two photons of very high energy. Such photons are also produced when a Higgs boson decays. Hence, we speak of a background process in the case of direct photon production. The result we are aiming at would be the first of its kind. In fact, we have been working on preparations for several years, and there are other competing groups doing the same.
Project Details
Project term
October 1, 2024–September 30, 2026
Affiliations
RWTH Aachen University
Institute
Institute for Theoretical Particle Physics and Cosmology
Principal Investigator
Methods
The predictions are obtained using Quantum Field Theory methods, which provide probability distributions for processes involving specific particles in function of the momenta of these particles. The probability distributions are given be highly-singular multi-dimensional integrals, which can only be solved using Monte Carlo methods. The project requires simulations in the several-million CPU-hours range. Due to its nature, trivial parallelisation over thousands of CPU cores is sufficient and no GPU resources are used. The main tool used for the calculations is a private software developed at the RWTH in the group of Prof. Czakon. This is currently the only software that can handle arbitrary scattering processes in Quantum Chromodynamics at second order of perturbation theory.
Results
In the current reporting period two results have been published. The first one concerns the effects of a virtual top- and bottom-quark on the cross section for the production of a Higgs boson. These effects were the topic of discussion in the community for many years. With the publication, it has been finally possible to settle the discussion and provide a reliable estimate of the effect at the few percent level as required by the precision of current measurements. The second publication concerns predictions for the production rate of hadrons which contain the b-quark. The publication demonstrates the necessity to include subtle effects of Quantum Chromodynamics. It has been received with great interest by the community, as the results can be used to better understand the structure of B hadrons.
Discussion
The publications pave the way for even more complex calculations. We expect to soon publish novel results for top-quark pair production in association with a jet. The cross section for this process can be used for the determination of the top-quark mass and strong coupling constant. There are, furthermore, proposals to measure energy correlations in top-quark events, which would also require our predictions. At the beginning of next year, results for cross sections for the production of a photon-pair should finally appear. We have recently found the solution to a long standing discrepancy in our predictions. Furthermore, we have obtained much more stable amplitudes for photons and additional quarks and gluons, which should make the calculation feasible. All these results are leading-edge science in this field of research. Most are published in the best journals, in particular in Phys. Rev. Lett.
Additional Project Information
DFG classification: 309 Particles, Nuclei and Fields
Software: The C++ library STRIPPER
Cluster: CLAIX
Publications
Czakon, Michał; Generet, Terry; Mitov, Alexander; Poncelet, Rene
Open B-Hadron Production at Hadron Colliders in QCD at Next-to-Next-to-Leading-Order and Next-to-Next-to-Leading-Logarithmic Accuracy
https://dx.doi.org/10.1103/b6pf-rj4h, 2025
Czakon, Michał ;Eschment, Felix; Niggetiedt, Marco; Poncelet, Rene; Schellenberger, Tom
Quark mass effects in Higgs production
https://dx.doi.org/10.1007/JHEP10(2024)210, 2024
Czakon, Michał; Eschment, Felix; Niggetiedt, Marco; Poncelet, Rene; Schellenberger, Tom
Top-Bottom Interference Contribution to Fully-Inclusive Higgs Production
https://dx.doi.org/10.48550/arXiv.2312.09896, 2023
Badger, Simon; Czakon, Michał; Hartanto, Heribertus Bayu; Moodie, Ryan; Peraro, Tiziano; Poncelet, Rene; Zoia, Simone
Isolated photon production in association with a jet pair through next-to-next-to-leading order in QCD
https://dx.doi.org/10.1007/JHEP10(2023)071, 2023
Alvarez, Manuel ; Cantero, Josu ; Czakon, Michal ; Llorente, Javier ; Mitov, Alexander ; Poncelet, Rene
NNLO QCD corrections to event shapes at the LHC
https://dx.doi.org/10.1007/JHEP03(2023)129, 2023
Thesis:
Schellenberger, Tom Claus Rudolf
Finite-quark-mass effects on the higgs production cross section in the gluon-gluon fusion channel
https://dx.doi.org/10.18154/RWTH-2025-06647, 2025
Generet, Terry
B-hadron production at higher orders in QCD
https://dx.doi.org/10.18154/RWTH-2023-07515, 2023