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 language | English |
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Article number | 242501 |
Journal | Physical Review Letters |
Volume | 122 |
Issue number | 24 |
DOIs | |
State | Published - 21 Jun 2019 |