Solution of Orthopositronium lifetime Puzzle

TL;DR

This paper precisely measures the decay rate of orthopositronium in silica powder, confirming consistency with quantum electrodynamics predictions and recent experimental results, thereby resolving the longstanding orthopositronium lifetime puzzle.

Contribution

The study introduces a direct $2 ext{γ}$ correction method for accurate decay rate measurement, achieving twice the previous precision and confirming theoretical predictions.

Findings

Decay rate measured as 7.0396±0.0012(stat)±0.0011(sys) μs^{-1}

Results align with $O(α^2)$ QED predictions

Consistent with recent nanoporous film measurements

Abstract

The intrinsic decay rate of orthopositronium formed in ${\rm SiO_2}$ powder is measured using the direct $2\gamma$ 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 $7.0396\pm0.0012 (stat.)\pm0.0011 (sys.)\mu s^{-1}$, which is consistent with our previous measurements with about twice the accuracy. Results agree well with the $O(\alpha^2)$ QED prediction, and also with a result reported very recently using nanoporous film.