# MuCap: Muon Capture on the Proton

### Submission summary

 As Contributors: Malte Hildebrandt Preprint link: scipost_202101_00009v3 Date accepted: 2021-03-31 Date submitted: 2021-02-03 08:59 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. The parameter $\Lambda_S$ 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:
Publication decision taken: accept

Editorial decision: For Journal SciPost Physics Proceedings: Publish
(status: Editorial decision fixed and (if required) accepted by authors)

### List of changes

page 1, line 20: g_P (??) -> g_P
reference to Section 5 [2] is given in line 22 and footnote 1

page 2, footnote 2: ... in (??) -> ... in Section 5 [2]