2008/03/13 by P. Kammel, Kammel, Peter
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Neutrino Physics Research #Nuclear Experiment (nucl-ex) #Particle physics theoretical and experimental studies
paper · pdf · doi:10.48550/arxiv.0803.1892
openalex publication_date 2008/03/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The singlet capture rate ΛS for the semileptonic weak process μ+p → n+νμ has been measured in the MuCap experiment. The novel experimental technique is based on stopping muons in an active target, consisting of a time projection chamber operating with ultra-pure hydrogen. This allows the unambiguous determination of the pseudoscalar form factor gP of the charged electroweak current of the nucleon. Our first result gP(q2=-0.88 m2μ) = 7.3 ± 1.1 is consistent with accurate theoretical predictions and constitutes an important test of QCD symmetries. Additional data are being collected with the aim of a three-fold reduction of the experimental uncertainties. Building on the developed advanced techniques, the new MuSun experiment is being planned to measure the muon capture rate on the deuteron to 1.5% precision. This would provide the by far most accurate experimental information on the axial current interacting with the two-nucleon system and determine the low energy constant L1A relevant for solar neutrino reactions. Muon induced atomic and molecular processes represent challenges as well as opportunities for this science program, and their interplay with the main nuclear and weak-interaction physics aspects will be discussed.