arXiv:0712.2442·v1·High Energy Physics — Phenomenology
Measurement of the Proton Asymmetry Parameter C in Neutron Beta Decay
M. Schumann🇩🇪 · M. Kreuz🇫🇷 · M. Deissenroth🇩🇪 · F. Glueck🇩🇪 · J. Krempel🇩🇪 · B. Maerkisch🇩🇪 · D. Mund🇩🇪 · A. Petoukhov🇫🇷 · T. Soldner🇫🇷 · H. Abele🇩🇪
Abstract
The proton asymmetry parameter C in neutron decay describes the correlation between neutron spin and proton momentum. In this Letter, the first measurement of this quantity is presented. The result C=-0.2377(26) agrees with the Standard Model expectation. The coefficient C provides an additional parameter for new and improved Standard Model tests. From a differential analysis of the same data (assuming the Standard Model), we obtain lambda=-1.275(16) as ratio of axial-vector and vector coupling constant.
Comments: 4 pages, 2 figures