Improved Measurement of the Positive-Muon Lifetime and Determination of the Fermi Constant

2007/04/30 by MuLan Collaboration, D. B. Chitwood, T. Banks +55 · 3 citations
Engineering · Physics and Astronomy · #Muon and positron interactions and applications #Particle physics theoretical and experimental studies #Superconducting Materials and Applications #hep-ex #nucl-ex

paper · pdf · doi:10.1103/physrevlett.99.032001

published as Phys.Rev.Lett.99:032001,2007 · As published version (PRL, July 2007)

openalex publication_date 2007/07/16 · arxiv created 2008/02/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01

Abstract

The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, \ensuremathτ_\ensuremathμ=2.197 013(24) \ensuremathμs, is in excellent agreement with the previous world average. The new world average \ensuremathτ_\ensuremathμ=2.197 019(21) \ensuremathμs determines the Fermi constant G_F=1.166 371(6)\ifmmode×\else\texttimes\fi10^\ensuremath-5 GeV^\ensuremath-2 (5 ppm). Additionally, the precision measurement of the positive-muon lifetime is needed to determine the nucleon pseudoscalar coupling g_P.

Cited by

• Physics at a future Neutrino Factory and super-beam facility
• Mass Effects in Muon and Semileptonicb→cDecays
• Limits on the time variation of the Fermi constantGFbased on type Ia supernova observations