Is the Unitarity of the quark-mixing-CKM-matrix violated in neutron $\beta$-decay?

H. Abele, M. Astruc Hoffmann, S. Baessler +6

We report on a new measurement of neutron $\beta$-decay asymmetry. From the result \linebreak $A_0$ = -0.1189(7), we derive the ratio of the axial vector to the vector coupling constan…