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Muonic Lithium atoms: nuclear structure corrections to the Lamb shift

by S. Li Muli, A. Poggialini, S. Bacca

This is not the current version.

Submission summary

As Contributors: Simone Salvatore Li Muli
Arxiv Link: https://arxiv.org/abs/1910.14370v1
Date submitted: 2019-11-01
Submitted by: Li Muli, Simone Salvatore
Submitted to: SciPost Physics Proceedings
Proceedings issue: 24th European Few Body Conference (University of Surrey, U.K.)
Discipline: Physics
Subject area: Nuclear Physics - Theory
Approaches: Theoretical, Computational

Abstract

In view of the future plans to measure the Lamb shift in muonic Lithium atoms we address the microscopic theory of the $\mu$-$^6$Li$^{2+}$ and $\mu$-$^7$Li$^{2+}$ systems. The goal of the CREMA collaboration is to measure the Lamb shift to extract the charge radius with high precision and compare it to electron scattering data or atomic spectroscopy to see if interesting puzzles, such as the proton and deuteron radius puzzles, arise. For this experiment to be successful, theoretical information on the nuclear structure corrections to the Lamb shift is needed. For $\mu$-$^6$Li$^{2+}$ and $\mu$-$^7$Li$^{2+}$ there exist only estimates of nuclear structure corrections based on experimental data that suffer from very large uncertainties. We present the first steps towards an ab initio computation of these quantities using few-body techniques.

Current status:
Has been resubmitted


Submission & Refereeing History

Resubmission 1910.14370v2 on 17 December 2019
Submission 1910.14370v1 on 1 November 2019

Reports on this Submission

Report 1 by Krzysztof Pachucki on 2019-12-3 Invited Report

  • Cite as: Krzysztof Pachucki, Report on arXiv:1910.14370v1, delivered 2019-12-03, doi: 10.21468/SciPost.Report.1361

Report

This is a valuable work. The calculation of the leading nuclear
structure corrections to the Lamb shift in muonic lithium atoms
is crucial for the interpretation of the planned measurements.
However, several specific comments or questions shall be addressed
before approving this work for the publication, namely:

Requested changes

1: the proton radius puzzle is merely the disagreement between
Paris measurements in hydrogen with all the rest.
CODATA 2014, H world data 2014 are all based on Paris measurements,
so they are not independent, as Figure 1 would suggest.
Moreover, the recent PRAD value (published in NATURE)
of the proton charge radius is also in agreement with muH rp.
CODATA 2018 also assumed smaller proton radius.
So to my opinion, there is no basis for heating this proton radius puzzle.

2: Authors should clarify the meaning of Lamb shift in \delta_{LS},
it is not 2S-2P but 2S - 2P_{1/2} energy difference.

3: It is not clear what Authors mean by discovery of the deuteron radius puzzle,
since r_d^2 - r_p^2 agrees between electronic and muonic measurements.
Do Authors consider it to be an independent puzzle ?

4: Authors define \delta_{TPE} as a nuclear structure corrections of order (Z alpha)^5,
however \delta_C^{(0)} in Eq. (6) is of higher order in Z alpha.
What is the basis to call it a two-photon exchange TPE correction ?

5: \delta^N in Eq. (1) is not defined anywhere.

6: After Eq. (8) Authors claim the \phi^2(0) is a squared wave function,
define \beta and \lambda which have not yet been used so far. Moreover,
if r_n is defined to be the neutron charge radius, how come r_n^2 is negative.

7: Authors elaborate on page 6 the calculations of \delta_{Z1}^{(1)} and \delta_{Z3}^{(1)}
which obviously cancel out in the sum in Eq. (1), explanations are needed.

8: A better representation of works by others on nuclear structure effects would be in place.

  • validity: high
  • significance: ok
  • originality: low
  • clarity: ok
  • formatting: good
  • grammar: good

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