# Pionic hydrogen and deuterium

### Submission summary

 As Contributors: Detlev Gotta Preprint link: scipost_202102_00018v1 Date submitted: 2021-02-11 12:48 Submitted by: Gotta, Detlev Submitted to: SciPost Physics Proceedings Proceedings issue: Review of Particle Physics at PSI Academic field: Physics Specialties: Nuclear Physics - Experiment Approach: Experimental

### Abstract

The measurement of strong-interaction shift and broadening in pionic hydrogen and deuterium yields pion-nucleon scattering lengths as well as the threshold pion-production strength on isoscalar NN pairs. Results from recent high-resolution experiments at PSI using crystal spectrometers allow important comparisons with the outcome of the modern low-energy description of QCD within the framework of effective field theories.

###### Current status:
Has been resubmitted

### Submission & Refereeing History

Resubmission scipost_202102_00018v2 on 23 March 2021

Submission scipost_202102_00018v1 on 11 February 2021

## Reports on this Submission

### Anonymous Report 2 on 2021-3-8 (Invited Report)

• Cite as: Anonymous, Report on arXiv:scipost_202102_00018v1, delivered 2021-03-08, doi: 10.21468/SciPost.Report.2664

### Report

This paper is in general sound an a beautiful piece of work. It should be published and I have only a few
more or less formal criticismes:
(i) The lettering in Figure 14.3, both on axis and in the figure itself is too small, i.e., less than 1 mm.
It is really very hard to read. One should follow the AIP Style Manual
https://web.mit.edu/me-ugoffice/communication/aip_style_4thed.pdf and increase the letters by about 50 %.
(ii) The symbol $\alpha$ is used on line 55 for the ,,fine structure constant'' and on line 157 for the pion
production strength. They say, however, what is what at the respective places.
(iii)Line 118: Having in mind the almost endless discussions on Coulomb de-excitation yields, it might be polite
to cite the respective work here.
(iv) Line 61: Again following the AIP Style Manual, one should not start a sentence with a Symbol or a number.
Why not leave away the full stop behind Eq. 14.2 and continue with ,,where $a^+ ... ### Requested changes This paper is in general sound an a beautiful piece of work. It should be published and I have only a few more or less formal criticismes: (i) The lettering in Figure 14.3, both on axis and in the figure itself is too small, i.e., less than 1 mm. It is really very hard to read. One should follow the AIP Style Manual https://web.mit.edu/me-ugoffice/communication/aip_style_4thed.pdf and increase the letters by about 50 %. (ii) The symbol$\alpha$is used on line 55 for the ,,fine structure constant'' and on line 157 for the pion production strength. They say, however, what is what at the respective places. (iii)Line 118: Having in mind the almost endless discussions on Coulomb de-excitation yields, it might be polite to cite the respective work here. (iv) Line 61: Again following the AIP Style Manual, one should not start a sentence with a Symbol or a number. Why not leave away the full stop behind Eq. 14.2 and continue with ,,where$a^+ ...

• validity: high
• significance: high
• originality: top
• clarity: high
• formatting: good
• grammar: good

### Author:  Detlev Gotta  on 2021-03-13  [id 1302]

(in reply to Report 2 on 2021-03-08)
Category:
correction

The referee comments have have included as following:

(i) The lettering in Figure 14.3, both on axis and in the figure itself is too small, i.e., less than 1 mm.
It is really very hard to read. One should follow the AIP Style Manual
https://web.mit.edu/me-ugoffice/communication/aip_style_4thed.pdf and increase the letters by about 50 %.
*Fig. 14.3 has been replaced after changing the lettering.

(ii) The symbol α is used on line 55 for the ,,fine structure constant'' and on line 157 for the pion
production strength. They say, however, what is what at the respective places.
*We are aware of this problem using identical symbols. As this nomenclature is established in the
corresponding fields we decided to leave it and hope the explanation at the place where the symbols are used is sufficient to avoid confusion.

(iii)Line 118: Having in mind the almost endless discussions on Coulomb de-excitation yields, it might be polite to cite the respective work here.
*We added 3 references which about demonstrate the development with the years of that subject (refs. [16-18]) of the updated version:
[16] L. Bracchi and G. Fiorentini, "Coulomb de-excitation of mesic hydrogen", Nuovo
Cim. A 43, 9 (1978).
[17] T. S. Jensen and V. E. Markushin, "Atomic cascade and precision physics with
light muonic and hadronic atoms", Lec. Notes Phys. 627, 37 (2003).
[18] V. P. Popov and V. N. Pomerantsev, "Coulomb deexcitation of pionic hydrogen
within close-coupling method", Phys. Rev. A 73, 040501(R) (2006).

(iv) Line 61: Again following the AIP Style Manual, one should not start a sentence with a Symbol or a number.
Why not leave away the full stop behind Eq. 14.2 and continue with ,,where \$a^+ ...
*We have rearranged the sentence to:
In terms of the isospin combinations I = 1=2 and I = 3=2, a+ and a- are given by:

The updated version of the article is communicated to the editor via optional remarks
as file PiHD_2021_03_09.pdf

### Report 1 by Adrian Signer on 2021-2-26 (Invited Report)

• Cite as: Adrian Signer, Report on arXiv:scipost_202102_00018v1, delivered 2021-02-26, doi: 10.21468/SciPost.Report.2620

### Report

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.

• validity: -
• significance: -
• originality: -
• clarity: -
• formatting: -
• grammar: -

### Detlev Gotta  on 2021-02-28  [id 1269]

Category:
remark

I would like to mention that ref.

[10] A. Hirtl et al., "Redetermination of the strong-interaction width in pionic hydrogen",
to be published in Eur. Phys. J. A (2021).

can be updated to

[10] A. Hirtl et al., "Redetermination of the strong-interaction width in pionic hydrogen",
Eur. Phys. J. A 57, 70 (2021).