Speaker
Description
Precision spectroscopy of rovibrational transitions in the HD$^+$ molecular ion has made significant progress in the past few years, allowing to improve the determination of the proton-electron mass ratio as well as beyond-standard-model physics constraints. In this talk, a few directions for future advances will be discussed, both from an experimental and theoretical point of view.
Firstly, we explore the idea of measuring transitions that involve more excited vibrational levels, whose sensitivity on the nuclear-to-electron mass ratios is either close to zero or positive (rather than negative, as is the case for transitions between low-lying states that have been measured so far). We will show how this allows to bypass, to some extent, the theoretical precision limit associated with uncalculated higher-order QED contributions. As a result, not only the mass ratios, but also the Rydberg constant and nuclear charge radii can in principle be substantially improved by measuring a well-chosen set of transitions [1].
Secondly, we will discuss an area of theory that requires new consideration, namely the relativistic and relativistic-recoil corrections of order $𝑚\alpha^6$. The pure relativistic correction has been so far evaluated only in the adiabatic approximation, whereas one of the contributions to the recoil part was only estimated using results obtained in hydrogen-like atoms. Calculations performed in a full three-body approach will be presented.
[1] S. Schiller and J.-Ph. Karr, accepted for publication in Phys. Rev. A.
