Speaker
Description
Compact exotic atoms involve replacing one or more electrons with negative exotic particles, such as muons or antiprotons. Contact-full transitions, i.e., those that involve an "s" state, are useful for measuring nuclear radii and QCD contact terms. On the other hand, contact-free transitions allow for comparisons of experiment and theory largely free from difficult-to-calculate nuclear effects. Such comparisons enable to test QED at extreme fields and to competitively search for new physics mediated by bosons of mass larger than an MeV.
The relevant transitions primarily emit photons with energies in the range of 5 to 200 keV, where conventional detection techniques fall short. Here, I will discuss how cryogenic microcalorimeters, novel quantum-sensing detectors for particle energies, are enabling the next generation of experiments beyond the state of the art. I will focus on promising prospects with hadronic atoms [1] and show preliminary results from the QUARTET collaboration of a high-resolution measurement of a contact-free transition in muonic oxygen.
[1] H Liu, BO, O Shtaif & Y Soreq, PRL 135, 131803 (2025)