The &lt;em&gt;π&lt;/em&gt;&lt;sup&gt;0&lt;/sup&gt; mass and the first experimental verification of Coulomb de-excitation in pionic hydrogen

Daum, Manfred; Kettle, P.-R.

doi:10.21468/SciPostPhysProc.5.012

The π⁰ mass and the first experimental verification of Coulomb de-excitation in pionic hydrogen

Citation

Daum, M., & Kettle, P. R. (2021). The π⁰ mass and the first experimental verification of Coulomb de-excitation in pionic hydrogen. In C. Hoffman, K. Kirch, & A. Signer (Eds.), SciPost physics proceedings: Vol. 5. PSI particle physics (p. 012 (10 pp.). https://doi.org/10.21468/SciPostPhysProc.5.012

Persistent URL https://www.dora.lib4ri.ch/psi/islandora/object/psi:38578

The most precise value for the π⁰ mass was obtained from the measurement of the mass difference m_π-m_π⁰ = 4.59364(48)\,MeV/c² in the charge exchange reaction π^-p^→π⁰n at PSI. With the most precise charged pion mass value, m_π⁺ = 139.57021(14)\,MeV/c² and the validity of the CPT theorem (m_π^_- = m_π⁺), a value m_π⁰ = 134.97657(50)\,MeV/c² is obtained. The measurements also revealed, for the first time, evidence of an unexpectedly large contribution from Coulomb de-excitation states during the pionic atom cascade.