A new measurement of the neutron β-decay asymmetry A0 has been carried out by the UCNA collaboration using polarized ultracold neutrons (UCN) from the solid deuterium UCN source at the Los Alamos Neutron Science Center (LANSCE). Improvements in the experiment have led to reductions in both statistical and systematic uncertainties leading to A0=−0.11954(55)stat.(98)syst., corresponding to the ratio of axial-vector to vector coupling λ≡gA/gV=−1.2756(30).
@article{arxiv.1210.7048,
title = {Precision Measurement of the Neutron Beta-Decay Asymmetry},
author = {M. P. Mendenhall and R. W. Pattie and Y. Bagdasarova and D. B. Berguno and L. J. Broussard and R. Carr and S. Currie and X. Ding and B. W. Filippone and A. García and P. Geltenbort and K. P. Hickerson and J. Hoagland and A. T. Holley and R. Hong and T. M. Ito and A. Knecht and C. -Y. Liu and J. L. Liu and M. Makela and R. R. Mammei and J. W. Martin and D. Melconian and S. D. Moore and C. L. Morris and A. Pérez Galván and R. Picker and M. L. Pitt and B. Plaster and J. C. Ramsey and R. Rios and A. Saunders and S. J. Seestrom and E. I. Sharapov and W. E. Sondheim and E. Tatar and R. B. Vogelaar and B. VornDick and C. Wrede and A. R. Young and B. A. Zeck},
journal= {arXiv preprint arXiv:1210.7048},
year = {2013}
}