# MuCap: Muon Capture on the Proton

### Submission summary

 As Contributors: Malte Hildebrandt Preprint link: scipost_202101_00009v1 Date submitted: 2021-01-13 17:17 Submitted by: Hildebrandt, Malte Submitted to: SciPost Physics Proceedings Proceedings issue: PSI Particle Physics Academic field: Physics Specialties: Nuclear Physics - Experiment Approach: Experimental

### Abstract

The singlet muon capture rate $\Lambda_S$ on the proton $\mu^-\ p \to \nu_\mu n$ is determined in a high precision lifetime measurement. The main apparatus consists of a new hydrogen time projection chamber as muon detector, developed by PSI, surrounded by cylindrical wire chambers and a plastic scintillator hodoscope as electron detectors. $\Lambda_S$ is evaluated as the difference between the inverse $\mu\,p$ lifetime and that of the free $\mu^+$. The result $\Lambda_S^\text{MuCap} = (715.6 \pm 5.4^\text{stat} \pm 5.1^\text{sys})\,\text{s}^{-1}$ is in excellent agreement with the prediction of chiral perturbation theory $\Lambda_S^{\chi\text{PT}} = (715.4 \pm 6.9)\,\text{s}^{-1}$. From $\Lambda_S^\text{MuCap}$ a recent analysis derives for the induced pseudoscalar coupling $g^\text{MuCap}_p = 8.23 \pm 0.83$ whereas $\bar{g}^{\chi\text{PT}}_p = 8.25 \pm 0.25$.}

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

### Submission & Refereeing History

Resubmission scipost_202101_00009v3 on 3 February 2021
Resubmission scipost_202101_00009v2 on 1 February 2021

Submission scipost_202101_00009v1 on 13 January 2021

## Reports on this Submission

### Report

This is a beautiful experiment and I recommend publication! I have only a few very minor and only formal suggestions for changes, see below

### Requested changes

1) If one follows the the AIP Style manual, one should avoid to start a new sentence with a symbol or a number. So, one might change on line 11 ,,Lambda_s is evaluated... by e.g. ,,The parameter Lambda_s is evaluated ...

2) Line 20 g_p(??): One should correct this.

3) In the footnote on page 2: (??) , please correct.

4) The references [3,4] are mentioned on page 4 after reference [20] only. So, in the list of references, one should make the according changes.

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

### Author:  Malte Hildebrandt  on 2021-01-31

(in reply to Report 1 on 2021-01-30)
Category: