Details

Autor(en) / Beteiligte

• Daum, Manfred
• Kettle, Peter-R.

Titel

The mass of the 4\pi

Ist Teil von

• SciPost physics proceedings, 2021-09 (5), Article 011

Erscheinungsjahr

2021

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• The most precise value for the pion mass was determined from a precision measurement at PSI of the muon momentum in pion decay at rest, \pi^+ \rightarrow \mu^+ + \nu_{\mu} π + → μ + + ν μ . The result is m_{\pi^+} = 139.570\,21(14) m π + = 139.570 21 ( 14 ) ~MeV/c ^2 2 . This value is more precise, however, in agreement with the recent compilation of the Particle Data Group for m_{\pi^-} m π − . The agreement of m_{\pi^+} m π + with the recent measurement. This yields a new quantitative measure of CPT invariance in the pion sector: (m_{\pi^+} - m_{\pi^-})/m_{\pi}(\mbox{av}) = (-2.9 \pm 2.0)\cdot 10^{-6} ( m π + − m π − ) / m π ( av ) = ( − 2.9 ± 2.0 ) ⋅ 10 − 6 , an improvement by two orders of magnitude.