Welcome

The Collaborative Research Center Particle Physics Phenomenology after the Higgs Discovery is a joint venture of theoretical particle physicists from the Karlsruhe Institute of Technology, RWTH Aachen University, the University of Siegen, and Heidelberg University. It is supported by the German Research Foundation (DFG).

Particle physics has long established itself as an important research discipline focused on understanding nature at a fundamental level. The current knowledge is summarized in a theory called the Standard Model of particle physics that describes strong and electroweak interactions. The discovery of the Higgs boson in 2012 formally completes the Standard Model and provides us with a consistent mathematical framework that can be used to describe nature in fine detail. However, several aspects of the Standard Model force us to raise questions about the foundations of this theory. Many proposed answers to these questions suggest that the Standard Model is a low-energy approximation to a much more fundamental theory that we strive to discover.

Scientists of the CRC will conduct research in the phenomenology of elementary particles, focusing in particular on physics related to the Higgs boson, the physics of top quarks, electroweak gauge bosons, jets, and dark matter, as well as flavor physics. Our goal is to develop novel concepts and methodologies to search for physics beyond the Standard Model through precise measurements at the LHC, at flavor factories and elsewhere.

Open positions The CRC has openings for Ph.D. positions. More information can be found here, or directly contact the principal investigators.

News 29.09.–01.10.2025: Annual Meeting of the CRC TRR 257 The Annual Meeting 2025 of the CRC TRR 257 will take place in Siegen. Among the main goals of this meeting is to review the status of the current funding period and to make plans for the next proposal. More information about the meeting can be found here (posted on: 10.06.2025) 22.09.2025: More than a lifetime (Workshop) In this workshop we will cover theoretical and experimental aspects of lifetimes of heavy hadrons. Theory aspects include perturbative contributions to the free-quark decay, to 2-quark contributions (i.e. kinetic operator, chromomagnetic operator, Darwin operator,…) and to 4-quark contributions as well as non-perturbative contributions. The latter ones can be determined by lattice QCD studies, sum rule calculations and fits of inclusive semilpetonic decays. Experimental aspects include the state of the art measurements from ATLAS, Belle II, BES III, CMS and LHCb as well as an outlook for future prospects. More information can be found at: https://indico.physik.uni-siegen.de/event/498/overview (posted on: 17.06.2025) 15.9.–19.9.2025: IWR School on Machine Learning for Fundamental Physics This School aims to strengthen technical expertise and foster new connections related to machine learning in fundamental physics, in particular for advanced PhD students specializing in scientific machine learning. The school takes place at the Interdisciplinary Center for Scientific Computing (IWR) at Heidelberg University, September 15th-19th 2025. More information is available here. (posted on: 04.07.2025) 23.06.–24.06.2025: Beyond Flavour Physics The main goal of the event is to discuss new ideas and research directions in Higgs and top physics, as well as to explore potential flavor studies at future colliders. Another focus will be the interplay between high-energy physics and quantum information theory. Alongside the scientific presentations, we expect active discussions on these topics to foster new collaborations with the research groups in Siegen, especially in preparation for the third funding period of the CRC. More information can be found here. (posted on: 30.04.2025) 28.05.2025: Siegen mit Exzellenz (new podcast episode) Siegen ist exzellent! Alexander Lenz erklärt, was ein Exzellenzcluster ist, wie damit die Zukunft der Physik an der Uni Siegen gestaltet wird, und was das für unseren CRC bedeutet. Spotify Apple Podcasts Deezer (posted on: 28.05.2025) View all events

Recent Seminars The flavor path to new physics Claudia Cornella (CERN-TH), 31.07.2025, Karlsruhe Higgs physics Christoph Englert (U. Glasgow), 24.07.2025, Karlsruhe Scientific Communication Selina Beckmann (Johannes Gutenberg University of Mainz), 22.07.2025, Aachen Scientific Communication Selina Beckmann (Johannes Gutenberg University of Mainz), 22.07.2025, Aachen B anomalies Danny Van Dyk (U. Durham), 17.07.2025, Karlsruhe Measurement of Higgs boson production cross sections using 2022 and 2023 CMS data in the diphoton decay channel Max Wrabetz (RWTH Aachen University), 15.07.2025, Aachen Recent developments in Machine Learning for High Energy Physics Huilin Qu (CERN), 15.07.2025, Aachen Recent developments in Machine Learning for High Energy Physics Huilin Qu (CERN), 15.07.2025, Aachen Microwire-based superconducting nanowire single-photon detector (SNSPD) as a target and sensor for dark matter Chiara Capelli (U. Zurich), 10.07.2025, Karlsruhe An effective theory for heavy dark matter of any spin Joachim Brod (University of Cincinnati), 14.07.2025, Siegen View all seminars

Recent Publications Extrapolating Jet Radiation with Autoregressive Transformers A. Butter, F. Charton, J. M. Villadamigo, A. Ore, T. Plehn and J. Spinner Accurate Surrogate Amplitudes with Calibrated Uncertainties H. Bahl, N. Elmer, L. Favaro, M. Haußmann, T. Plehn and R. Winterhalder Precision calibration of calorimeter signals in the ATLAS experiment using an uncertainty-aware neural network The ATLAS Collaboration Profile Likelihoods on ML-Steroids T. Heimel, T. Plehn and N. Schmal Advancing Tools for Simulation-Based Inference H. Bahl, V. Bresò, G. De Crescenzo and T. Plehn view all publications