Measurement of the Weak Axial-Vector Coupling Constant in the Decay of Free Neutrons Using a Pulsed Cold Neutron Beam

B. Märkisch, H. Mest, H. Saul, X. Wang, H. Abele, D. Dubbers, M. Klopf, A. Petoukhov, C. Roick, T. Soldner, D. Werder

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Abstract

We present a precision measurement of the axial-vector coupling constant gA in the decay of polarized free neutrons. For the first time, a pulsed cold neutron beam was used for this purpose. By this method, leading sources of systematic uncertainty are suppressed. From the electron spectra we obtain λ=gA/gV=-1.27641(45)stat(33)sys, which confirms recent measurements with improved precision. This corresponds to a value of the parity violating beta asymmetry parameter of A0=-0.11985(17)stat(12)sys. We discuss implications on the Cabibbo-Kobayashi-Maskawa matrix element Vud and derive a limit on left-handed tensor interaction.

Original languageEnglish
Article number242501
JournalPhysical Review Letters
Volume122
Issue number24
DOIs
StatePublished - 21 Jun 2019

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