We briefly review how nonrelativistic effective field theories give us a definition of the QCD potentials and a coherent field-theory-derived quantum-mechanical scheme to calculate the properties of bound states made by two or more heavy quarks. In this framework heavy quarkonium properties depend only on the QCD parameters (quark masses and αs) and nonpotential corrections are systematically accounted for. The relation between the form of the nonperturbative potentials and the low-energy QCD dynamics is also discussed.

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Effective field theories for heavy quarkonium

http://inspirehep.net/record/691220/files/arXiv:hep-ph_0509010.pdf

Precision physics of simple atoms: QED tests, nuclear structure and fundamental constants

The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥106) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 107 cm−3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

/pdf/experimental-progress-in-positronium-laser-physics-1pzptprxni.pdf

Experimental progress in positronium laser physics

The gj factor of a bound electron and the hyperfine structure splitting in hydrogenlike ions

Two-Loop Correction to the Orthopositronium Decay Rate

The single photon annihilation contributions for the positronium ground state hyperfine splitting are calculated analytically to order ${m}_{e}{\ensuremath{\alpha}}^{6}$ using nonrelativistic QED. Based on intuitive physical arguments the same result can also be determined using results from previous calculations. Our result completes the hyperfine splitting calculation to order ${m}_{e}{\ensuremath{\alpha}}^{6}$. We compare the theoretical prediction with the most recent experimental measurement.

S. M. Zebarjad

Papers

Single Photon Annihilation Contributions to the Positronium Hyperfine Splitting to Order m e α 6