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The $\pi^0$ mass and the first experimental verification of Coulomb de-excitation in pionic hydrogen
by M. Daum and P.-R. Kettle
This Submission thread is now published as
Submission summary
| Submission information |
| Preprint Link: |
scipost_202105_00042v2
(pdf)
|
| Date accepted: |
2021-07-06 |
| Date submitted: |
2021-07-05 10:00 |
| Submitted by: |
Daum, Manfred |
| Submitted to: |
SciPost Physics Proceedings |
| Proceedings issue: |
Review of Particle Physics at PSI (PSI2020) |
| Ontological classification |
| Academic field: |
Physics |
| Specialties: |
- High-Energy Physics - Experiment
|
| Approach: |
Experimental |
Abstract
The most precise value for the $\pi^0$ mass was obtained from the measurement of the mass difference $m_{\pi^-}-m_{\pi^0} = 4.593\,64(48)$\,MeV/c$^2$ in the charge exchange reaction $\pi^-$p $\rightarrow \pi^0$n at PSI. With the most precise charged pion mass value, $m_{\pi^+} = 139.570\,21(14)$\,MeV/c$^2$ and the validity of the CPT theorem ($m_{\pi^-} = m_{\pi^+}$), a value $m_{\pi^0} = 134.976\,57(50)$\,MeV/c$^2$ 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.
