Precision measurements of positronium decay rate and energy level

Abstract

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 mu s^-1. It is the first result to validate the 2nd order correction. The Hyper Fine Splitting of positronium is sensitive to the higher order corrections of the QED prediction and also to the new physics beyond Standard Model via the quantum oscillation into virtual photon. The discrepancy of 3.5 sigma is found recently between the measured values and the QED prediction (O(alpha^3)). It might be due to the contribution of the new physics or the systematic problems in the previous measurements: (non-thermalized Ps and non-uniformity of the magnetic field). We propose new methods to measure HFS precisely without the these uncertainties.Comment: This note contributes to pbar0

Lorentz violation in simple QED processes

“…This means that an analysis of o-Ps could bring information on the spatial components of the background. However, since the experimental uncer-tainty is of similar size as for p-Ps [38], we do not expect better limits.…”

“…The decay rate of o-Ps is not significantly more precise than that of p-Ps and its relative precision reads 150 ppm [38]. The former is, however, a higher order process in QED, so we go for the simplest one, p-Ps, without significant loss regarding the outcoming bound on the LV parameters.…”

First millimeter-wave spectroscopy of ground-state positronium

“…The shift is corrected (+460 ppm) and the amount of this correction is conservatively assigned as a systematic error. A linear extrapolation is sufficient at the current experimental precision, however, as has recently been pointed out [18] [19], the We also estimate an uncertainty due to detection efficiencies obtained using GEANT4 simulation. Since S/N is used to obtain the cross-sections, only the relative efficiency between 2γ-and 3γ-decays takes part in the uncertainty.…”

Gauge invariant formulation of3γdecay of particle-antiparticle bound states

“…What makes this heuristic argument particularly compelling is that it can be applied to 4 One should, however, be careful not to confuse Eq. (29), which applies to models of QCD, with the equation S µ = eγ µ G, which follows from Eq.…”

“…A well known example of the Φ → 3γ transition is supplied by orthopositronium whose three-photon decay provides a laboratory for precision quantum electrodynamics (QED) tests [3,4]. Analogous decays of 3 S 1 quarkonia are much more difficult to study both experimentally and theoretically.…”