Related papers: Details on the ${\cal{O}}(m_e \alpha^6)$ Positroni…
The single photon annihilation contributions for the positronium ground state hyperfine splitting are calculated analytically to order $m_e\alpha^6$ using NRQED. Based on intuitive physical arguments the same result can also be determined…
We present the complete result for the ${\cal O}(\alpha^7m_e)$ one-photon annihilation contribution to the hyperfine splitting of the ground state energy levels in positronium. Numerically it increases the prediction of quantum…
We present an analytic calculation of the m*alpha^6 recoil corrections to the hyperfine splitting (HFS) of the ground state energy levels in positronium. We find \Delta E_{\rm rec} = m alpha^6 (-1/6 ln(alpha) + 331/432 -ln(2)/4 - 17…
The logarithmically enhanced alpha^7 ln(1/alpha) contribution to the hyperfine splitting of the positronium ground-state energy levels is calculated in the framework of dimensionally regularized nonrelativistic quantum electrodynamics. The…
The two-photon-annihilation contribution to the true muonium hyperfine splitting arising from $e$ and $\tau$ loops is obtained analytically at order $m_\mu\alpha^6$. The contribution to the hyperfine splitting is $-2.031092873…
Positronium spectroscopy (n=1 hyperfine splitting, n=2 fine structure, and the 1S-2S interval) has reached a precision of order 1 MHz. Vigorous ongoing efforts to improve the experimental results motivate the calculation of the positronium…
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 =…
We present an analytic calculation of the O(m alpha^6) recoil and radiative recoil corrections to energy levels of positronium nS states and their hyperfine splitting. A complete analytic formula valid to O(m alpha^6) is given for the…
We investigate one-photon annihilation of the electron-positron pair in the field of a central, very heavy and positively charged atomic nucleus. The explicit formula for the annihilation rate of this process $\Gamma^{(b)}_{1 \gamma}$ is…
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…
We have calculated all contributions to the energy levels of parapositronium at order $m \alpha^7$ coming from vacuum polarization corrections to processes involving virtual annihilation to two photons. This work is motivated by ongoing…
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…
We compute the next-to-leading, O(m alpha^5), contribution to the hyperfine splitting in positronium within the framework of NRQED. When applied to the ground state, our calculation reproduces known results, providing a further test of…
Hyperfine splitting of positronium is an important parameter for particle physics. This paper gives experimental techniques and results of R&D studies of our experiment to observe direct hyperfine transition of ortho-positronium to…
An "ultrafine" splitting in positronium between the $L=1$ spin-singlet state and the spin-average of the spin-triplet states is shown to arise only at order $\alpha^6$. The QED prediction for $n=2$ states is…
We consider hard three-loop nonlogarithmic corrections of order $m\alpha^7$ to hyperfine splitting in positronium. All these contributions are generated by the graphs with photon and/or electron loop radiative insertions in the two-photon…
The "recoil" correction of order $m \alpha^6$ to the hyperfine splitting of positronium ground state was found. The formalism employed is based on the noncovariant perturbation theory in QED. Equation for two-particle component of full…
The complete contribution to the muonium hyperfine splitting of relative order alpha^3(m_e/m_mu)ln(alpha) is calculated. The result amounts to 0.013 kHZ, much smaller than suggested by a previous estimate, and leads to a 2-sigma shift of…
Ongoing improvements in the measurement of positronium transition intervals motivate the calculation of the $O(m \alpha^7)$ corrections to these intervals. In this work we focus on corrections to the spin-singlet parapositronium energies…
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…