Shape function in QED and bound muon decays

Abstract

When a particle decays in an external field, the energy spectrum of the products is smeared. We derive an analytical expression for the shape function accounting for the motion of the decaying particle and the final state interactions. We apply our result to calculate the muonium decay spectrum and comment on applications to the muon bound in an atom.

5 pages, 3 figures v2: Corrected verrsion to appear in PRD

References in corpus (4)

• Muon decay in orbit: spectrum of high-energy electrons
• Michel decay spectrum for a muon bound to a nucleus
• Decay of negative muons bound in ${}^{27}$Al
• Shape and soft functions of HQET and SCET in the 't Hooft Model

Cited by in corpus (3)

• COMET Phase-I Technical Design Report
• High-energy electrons from the muon decay in orbit: radiative corrections
• Bound muon decay spectrum in the leading logarithmic accuracy