학술논문
Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling $g_P$
Document Type
Working Paper
Author
Andreev, V. A.; Banks, T. I.; Case, T. A.; Chitwood, D. B.; Clayton, S. M.; Crowe, K. M.; Deutsch, J.; Egger, J.; Freedman, S. J.; Ganzha, V. A.; Gorringe, T.; Gray, F. E.; Hertzog, D. W.; Hildebrandt, M.; Kammel, P.; Kiburg, B.; Knaack, S.; Kravtsov, P. A.; Krivshich, A. G.; Lauss, B.; Lynch, K. L.; Maev, E. M.; Maev, O. E.; Mulhauser, F.; Özben, C. S.; Petitjean, C.; Petrov, G. E.; Prieels, R.; Schapkin, G. N.; Semenchuk, G. G.; Soroka, M. A.; Tishchenko, V.; Vasilyev, A. A.; Vorobyov, A. A.; Vznuzdaev, M. E.; Winter, P.
Source
Phys.Rev.Lett.99:032002,2007
Subject
Language
Abstract
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.
Comment: submitted to Phys.Rev.Lett
Comment: submitted to Phys.Rev.Lett