Related papers: Muonium fine structure: theory update, tests of Lo…
We report a microwave spectroscopy measurement of the muonium $2S_{1/2}-2P_{3/2}$ fine structure transition, yielding a transition frequency of $9871.0 \pm 7.0~\mathrm{MHz}$, in agreement with state-of-the-art QED predictions within one…
The energy levels of the muonium ($\mu^+ e^-$) atom, which consists of two ''point-like'' leptonic particles, can be calculated to very high accuracy in the framework of bound state Quantum Electrodynamics (QED), since there are no…
Terms contributing to the hyperfine structure of the muonium ground state at the level of few tenths of kHz have been evaluated. The $\alpha^2 (Z\alpha)$ radiative correction has been calculated numerically to the precision of 0.02 kHz.…
In the framework of the quasipotential method we calculate the contributions of the kind (Z\alpha)^6m_e^2/m_\mu to the energy spectrum of the muonium n^3S_1 states. Numerical value of obtained correction for 2^3S_1-1^3S_1 muonium fine…
Precision experiments with muons are sensitive to Planck-scale CPT and Lorentz violation that is undetectable in other tests. Existing data on the muonium ground-state hyperfine structure and on the muon anomalous magnetic moment could be…
The status of Lorentz- and CPT-violation searches using measurements of the anomalous magnetic moment of the muon is reviewed. Results from muon g-2 experiments have set the majority of the most stringent limits on Standard- Model Extension…
On the basis of quasipotential approach to the bound state problem in QED we calculate the vacuum polarization, relativistic, recoil, structure corrections of orders $\alpha^5$ and $\alpha^6$ to the fine structure interval $\Delta…
Muons are puzzling physicists since their discovery when they were first thought to be the meson predicted by Yukawa to mediate the strong force. The recent results at Fermilab on the muon g-2 anomaly puts the muonic sector once more under…
We present the status and the prospects of the ongoing efforts to improve the measurements of the 1S-2S transition in positronium and muonium. These purely leptonic systems represent ideal objects to test bound-state QED to high precision…
Upon a suggestion of Kostelecky et al., we have performed a test of CPT and Lorentz invariance from the microwave spectroscopy of muonium. New terms in their standard model extension violating CPT and Lorentz symmetry would appear as…
Corrections of orders $\alpha^5$ and $\alpha^6$ are calculated in the fine structure interval $\Delta E^{fs}=E(2P_{3/2})-E(2P_{1/2})$ and in the hyperfine structure of the energy levels $2P_{1/2}$ and $2P_{3/2}$ in muonic hydrogen. The…
The muonium atom is the purely leptonic bound state of a positive muon and an electron. It has a lifetime of 2.2 $\mu$s. The absence of any known internal structure provides for precision experiments to test fundamental physics theories and…
In attempts to unify the four known fundamental forces in a single quantum-consistent theory, it is suggested that Lorentz symmetry may be broken at the Planck scale. Here we search for Lorentz violation at the low-energy limit by comparing…
The prospects are explored for testing Lorentz and CPT symmetry in the muon sector via the spectroscopy of muonium and various muonic atoms, and via measurements of the anomalous magnetic moments of the muon and antimuon. The effects of…
Some recent precision experiments in low energy muon physics are discussed. Spectroscopy on the muonium atom, the bound state of a positve muon and an electron, has provided precise tests of standard theory and yielded most precise values…
We present an updated value of the Muonium 1S-2S transition frequency, highlighting contributions from different QED corrections as well as the large uncertainty in the Dirac contribution, stemming from the uncertainty of the…
Absolute transition frequencies of the $2s\; ^2{\rm S}_{1/2} \rightarrow 2p\;^2\mathrm{P}_{1/2,3/2}$ transitions in Be$^+$ were measured for the isotopes $^{7,9-12}$Be. The fine structure splitting of the $2p$ state and its isotope…
An overview of the theoretical framework of the Standard Model Extension (SME) that allows for a parametrization of Lorentz and CPT violating effects using effective field theory will be presented. A review of current bounds on these…
Following a suggestion of Kostelecky et al. we have evaluated a test of CPT and Lorentz invariance from the microwave spectroscopy of muonium. Hamiltonian terms beyond the standard model violating CPT and Lorentz invariance would contribute…
Large-scale {\em ab initio} QED calculations are performed for the $2p_{3/2}$--$2p_{1/2}$ fine-structure interval of Li-like ions with nuclear charges $Z = 5\,$--$\,92$. Improved theoretical predictions are obtained by combining together…