相关论文: Detection of the Direct Hyperfine Transition of Po…
We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop a new optical system to accumulate about…
Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS, about 203 GHz) is an important observable but all previous measurements of Ps-HFS had been measured indirectly using…
Interference between different energy eigenstates in a quantum system results in an oscillation with a frequency which is proportional to the difference in energy between the states. Such an oscillation is observable in polarized…
Positronium is an ideal system for the research of QED in the bound state. The hyperfine splitting of positronium (Ps-HFS: about 203 GHz) is a good tool to test QED and also sensitive to new physics beyond the Standard Model. Previous…
High-order perturbative corrections to positronium decays and hyperfine splitting are briefly reviewed. Theoretical predictions are compared to the most recent experimental data. Perspectives of future calculations are discussed.
Positronium is an ideal system for the research of the QED, especially for the QED in bound state. The discrepancy of 3.9\sigma is found recently between the measured HFS values and the QED prediction ($O(\alpha^3)$). It might be due to the…
We present the current status for the direct measurement of the positronium hyperfine structure using the $\text{2}^\text{3}\text{S}_\text{1} \rightarrow \text{2}^\text{1}\text{S}_\text{0}$ transition. This experiment, currently being…
Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS: about 203 GHz) is sensitive to new physics beyond the Standard Model via a vacuum oscillation between an ortho-Ps and a…
Hyperfine spectroscopy of positronium formed in the presence of a static magnetic field is considered. Generalising the situation hitherto developed in the literature, the magnetic field is not assumed to be parallel to the momentum of…
This talk gives an elementary introduction to the basic properties of positronium. Recent progress in theoretical studies of the hyperfine splitting and lifetime of the ground state is reviewed. Sensitivity of these precisely measured…
Positronium is an ideal system for the research of the bound state QED. New precise measurement of orthopositronium decay rate has been performed with an accuracy of 150 ppm, and the result combined with the last three is 7.0401 +- 0.0007…
We have calculated the contribution to the positronium hyperfine splitting at order $m \alpha^7$ of the light-by-light scattering process in the exchange of two photons between the electron and positron. Our result is $\Delta E =…
A detailed presentation is given of the analytic calculation of the single-photon annihilation contributions to the positronium ground state hyperfine splitting to order $m_e\alpha^6$ in the framework of non-relativistic effective theories.…
We obtain positronium Hyperfine Splitting owing to the non-commutativity of space and show that, in the leading order, it is proportional to $\theta \alpha^6$ where, $\theta$ is the parameter of non-commutativity. It is also shown that…
Numerous few-electron atomic systems are considered which can be used effectively for observing a potential variation of the fine-structure constant $\alpha$ and the electron-proton mass ratio $m_e/m_p$. We examine optical magnetic dipole…
The ground state hyperfine splitting of positronium, $\Delta_{\mathrm{HFS}}$, is sensitive to high order corrections of QED. A new calculation up to $\mathrm{O}(\alpha ^3 \ln \alpha)$ has revealed a $3.9\sigma$ discrepancy between the QED…
Molecular hydrogen ions are of metrological relevance due to the possibility of precise theoretical evaluation of their spectrum and of external-field-induced shifts. In homonuclear molecular ions the electric dipole $E1$ transitions are…
Recent and ongoing experimental work on the positronium spectrum motivates new efforts to calculate positronium energy levels at the level of three loop corrections. We have obtained results for one set of such corrections involving…
The decay of the para-positronium into two photons is studied in the framework of a composite Quantum Field Theoretical approach. This amounts to the evaluation of the electron-positron dressing together with the Weinberg compositeness…
We consider the production of ultrarelativistic parapositronium and orthopositronium atoms in collisions of high energy electrons with laser photons. Our results demonstrate the opportunity of intensive positronium beam formation with…