Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling $g_P
Phys.Rev.Lett.99:032002,2007 The rate of nuclear muon capture by the proton has been measured using a new experimental technique based on a time projection chamber operating in ultra-clean, deuterium-depleted hydrogen gas at 1 MPa pressure. The capture rate was obtained from the difference between t...
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Main Authors | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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Format | Journal Article |
Language | English |
Published |
16.04.2007
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Subjects | |
Online Access | Get full text |
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Summary: | Phys.Rev.Lett.99:032002,2007 The rate of nuclear muon capture by the proton has been measured using a new
experimental technique based on a time projection chamber operating in
ultra-clean, deuterium-depleted hydrogen gas at 1 MPa pressure. The capture
rate was obtained from the difference between the measured $\mu^-$
disappearance rate in hydrogen and the world average for the $\mu^+$ decay
rate. The target's low gas density of 1% compared to liquid hydrogen is key to
avoiding uncertainties that arise from the formation of muonic molecules. The
capture rate from the hyperfine singlet ground state of the $\mu p$ atom is
measured to be $\Lambda_S=725.0 \pm 17.4 s^{-1}$, from which the induced
pseudoscalar coupling of the nucleon, $g_P(q^2=-0.88 m_\mu^2)=7.3 \pm 1.1$, is
extracted. This result is consistent with theoretical predictions for $g_P$
that are based on the approximate chiral symmetry of QCD. |
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DOI: | 10.48550/arxiv.0704.2072 |