Atomic parity violation in muonic X-rays

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Muonic atoms are an excellent laboratory to study the interaction between the muon and the atomic nucleus as there is a large overlap of the muon wave function and the nucleus. Radiative atomic transitions, so-called muonic X-rays, yield accurate information on the size of the nucleus. In addition, the large overlap of the wave functions increases the sensitivity of this system for short-range interactions, in particular weak neutral currents inducing atomic parity violating effects in muonic X-rays. Data on neutral current effects at low energies is sparse however, and there is none with muons. New, muon specific interactions may introduce parity violating effects of the same order or larger than the amplitudes expected in the Standard Model of particle physics. These interactions are in part motivated by hints of physics beyond the Standard Model in recent muon data.In this proposal, we focus on the mixing of the opposite parity 2S and 2P atomic levels in muonic zinc. The scope of this proposal is:(a) to make a clean measurement of the single photon 2S-1S transition in zinc, determine its branching ratio in the atomic cascade, and to fully understand all relevant backgrounds. For this purpose, two measurements with a high-purity germanium detector array are planned at the Paul Scherrer Institute in Switzerland. A first beam time of two weak was approved this year.(b) to make an optimized experimental design for a future atomic parity violation experiment (APV) with muonic atoms, and to determine its beyond the Standard Model physics reach. (c) to make a significant contribution to the charge radius measurement of 226Ra. This measurement will serve as an important input for the upcoming atomic parity violating experiment with a single radium ion. (d) one PhD thesis at the Johannes Gutenberg University of Mainz.