Research funding Second Funding Period for DFG Research Unit in Physics
Press Release No. 29/2025
1 April 2025
German Research Foundation allocates funding worth approximately 5.6 million euros
The DFG Research Unit “Searching for charged lepton flavour violation with the Mu3e experiment” (FOR 5199) based in physics will be continuing its successful work in a second funding period. The German Research Foundation (DFG) has allocated funding worth 5.6 million euros for a period of four years. Together with colleagues from Karlsruhe and Mainz, as well as international partners from the United Kingdom and Switzerland, researchers from Heidelberg University will search for the possible decay of a positively charged muon elementary particle (Mu+) in two positrons (2e+) and an electron, by means of an ultramodern particle detector. Serving as spokesperson is Prof. Dr André Schöning from the Institute for Physics at Ruperto Carola.
In the Standard Model of particle physics there are rules prohibiting certain processes. One of these rules affects what is called the Lepton flavor, which has to be conserved when particles decay. “The muon, which is about 200 times heavier than the electron, is not a stable particle but usually decays into an electron, a neutrino and an antineutrino with a lifetime of about two microseconds. Observing a lepton flavor violating decay would be a sensational discovery, which could only be explained through the existence of new particles or new forces,” Prof. Schöning underlines.
The Heidelberg particle physicists are involved in the Mu3e experiment with two working groups. One of them, under the direction of Prof. Schöning at the Institute for Physics, constructed an ultra-thin silicon pixel detector that precisely records the position and direction of the decay particles. At the Kirchhoff Institute for Physics, the research group led by Prof. Dr Schultz-Coulon built a detector for measuring the timing of the decay particles with a resolution of under 100 picoseconds. Likewise involved in setting up and operating the Mu3e experiment at the Paul Scherrer Institute in Switzerland are researchers from the Johannes Gutenberg University Mainz, the Karlsruhe Institute of Technology, and also from the United Kingdom and Switzerland.
The now approved funding allows the Mu3e experiment to be concluded and so make an important contribution towards a better understanding of particle physics, beyond established theories. The first data is expected for 2026. Also funded are research and development activities for a detector upgrade, which is planned for the year 2030. This second phase will focus on boosting sensitivity to a new high in particle physics in order to detect this yet-to-be-observed decay. The physicists aim to achieve this by developing and applying new technologies when instrumenting the particle detector.