Solution of the Orthopositronium Lifetime Puzzle

Abstract

The intrinsic decay rate of orthopositronium formed in SiO2 powder is measured using the direct 2γ correction method such that the time dependence of the pick-off annihilation rate is precisely determined. The decay rate of orthopositronium is found to be 7.0396 ± 0.0012(stat.) ± 0.0011(sys.)µs −1 , which is consistent with our previous measurements with about twice the accuracy. Results agree well with the O(α 2 ) QED prediction, and also with a result reported very recently using nanoporous film.

Spin-half fermions with mass dimension one: theory, phenomenology, and dark matter

“…Over the years it had been suspected that mirror matter, apart from being a dark matter candidate, could also provide a resolution to the orthopositronium life time puzzle which had acquired a statistical significance well above the 5-σ level. Latest measurements by two independent groups, however, have discovered a systematic source of errors and now these latest experiments provide a decay rate which agrees well with predictions of quantum electrodynamics [119,120].…”

First test of $O(α^{2})$ correction of the orthopositronium decay rate

“…In this method, the thermalization process was directly measured and taken into account. This result has been confirmed by two different and more accurate (200 ppm) measurements [13,14] and the 'lifetime puzzle' has been solved [15]. Since the same results are obtained with different two methods( [11,13] [14]), these methods have the potential to measure decay rate more precisely.…”