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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
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Submission summary
| Authors (as registered SciPost users): | Manfred Daum |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202105_00042v1 (pdf) |
| Date submitted: | 2021-05-29 16:33 |
| Submitted by: | Daum, Manfred |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | Review of Particle Physics at PSI (PSI2020) |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| 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.
Current status:
Reports on this Submission
Report #2 by Claude Petitjean (Referee 2) on 2021-6-19 (Invited Report)
- Cite as: Claude Petitjean, Report on arXiv:scipost_202105_00042v1, delivered 2021-06-19, doi: 10.21468/SciPost.Report.3083
Strengths
1) very comprehensive description of the experiment resulting in the most precise determination of the pi_0 mass.
2) very comprehensive description of the method and evaluation of epithermal energies of pi-p atoms.
3) good presentation of analysis & fit of Coulomb deexcitations in pi-p atoms
Weaknesses
1) conclusions are missing from the analysis of Coulomb deexcitations
Report
The authors have written an excellent review of the experiment about the most precise pi_0 mass determination and significant Coulomb deexcitations of pi-p atoms observed in conjunction with this experiment. This paper is absolutely fit for publication in the SCiPost journal.
The paper would benefit if some comprehensive conclusions would be added to the analysis of Coulomb deexcitations (table 12.1). E.g. are the theories supported by this multi parameter fit?
Requested changes
1) add some conclusions to part 2 of the paper.
Report #1 by Adrian Signer (Referee 1) on 2021-6-17 (Invited Report)
- Cite as: Adrian Signer, Report on arXiv:scipost_202105_00042v1, delivered 2021-06-17, doi: 10.21468/SciPost.Report.3076
Report
We (the editors Cy Hoffman, Klaus Kirch, Adrian Signer) had the
opportunity to review an earlier draft of the article and were in
communication with the authors before the submission. All our comments
and suggestions have been taken into account. Hence, we think the
paper can now be published in the current form.