Laser spectroscopy of simple atoms is sensitive to properties of the atomic

nucleus, such as its charge and magnetization distribution, or its

polarizability. This allows determining the nuclear parameters from atomic

spectroscopy, but also limits the attainable precision for the determination of

fundamental constants or the test of QED and the Standard Model.

In light muonic atoms and ions, one negative muon replaces all atomic electrons,

resulting in a calculable hydrogen-like system. Due to the muon's large mass

(200 times the electron mass), the muon orbits the nucleus on a 200 times

smaller Bohr radius, increasing the sensitivity of muonic atoms to nuclear

properties by 200^3 = 10 million.

This has resulted in a 10fold increase in the precision of the charge radius of

the proton, deuteron, and the stable helium nuclei. The consequences for atomic

and nuclear physics, the determination of fundamental constants, and the test of

QED and the Standard Model are discussed.

https://www.dropbox.com/sh/69sdbudfg8245pj/AACTb2WyBF_R2ujBHJkIx6zja?dl=0