an attempt is made to show in a straightforward way how a body-fixed frame may be constructed in classical and hence in quantum mechanics for a polyatomic molecule with the aid of which the vibration-rotation behavior of the molecule may be described.

Laser spectroscopy of muonic atoms has been recently used to probe properties light nuclei with unprecedented precision. We introduce nuclear effects in hydrogen-like atoms, nucleon structure quantities (form factors, functions, polarizabilities), and their the Lamb shift hyperfine splitting (HFS) hydrogen (μH). Updated theory predictions for HFS μH are presented. review challenges ongoing effo...