QUARTET Experiment

• Aziza Zendour (PSI - Paul Scherrer Institut)

Room: WBGB/021 (TimeOut) To improve existing theoretical models and obtain accurate values for fundamental constants, precise measurements of absolute nuclear charge radii are necessary. These can help improve our knowledge of bound-state QED and aid in exploring new physics beyond the SM. While muonic atom spectroscopy is known for its precision, measuring 2p–1s transition energies for low-Z nuclei of 20–200 keV has proven to be challenging, due to the energy resolution limitations of solid-state detectors. The QUARTET collaboration aims to improve these measurements by using metallic magnetic calorimeters detector to conduct high-precision X-ray spectroscopy of low-lying states in muonic atoms.

A search for $\mu \to e\gamma$ with the highest sensitivity to date in the MEG II experiment

• Kensuke Yamamoto (The University of Tokyo)

Room: WBGB/021 (TimeOut) The MEG II experiment has been searching for lepton-flavour-violating $\mu \to e\gamma$ with the highest sensitivity in the world, utilising the most intense DC muon beam at PSI and innovative high-resolution detectors. We published the results last year using the first two years of data, in which there was no event excess and that the most stringent upper limit on the branching ratio of $\mu \to e\gamma$ was set to $1.5 \times 10^{-13}$ at 90% confidence level. This talk will present the motivation, essence and challenges of a rare-decay search in the MEG II experiment.