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An Upper Bound on Parity Violating Neutron Spin Rotation in He-4



Jeffrey S. Nico, William M. Snow, Christopher D. Bass, Tiffany D. Bass, B. E. Crawford, K. F. Gan, B R. Heckel, D Lou, D M. Markoff, A M. Micherdzinska, Hans P. Mumm, A. K. Opper, M Sarsour, E I. Sharapov, H E. Swanson, S. C. Walbridge, V Zhumabekova


We report an upper bound on parity violating neutron spin rotation in He-4. This experiment is the most sensitive search for neutron weak optical activity yet performed. Our result for the neutron spin rotation angle per unit length in He-4 is dphi/dz = (+1.7 +/- 9.1(stat) +/- 1.4(sys))x10^{-7} rad/m. The statistical uncertainty is smaller than the best current estimates of the range of possible values of dphi/dz in n+He-4. The systematic uncertainty achieved using our experimental technique is small enough to encourage more precise measurements.
Physics Letters B


cold neutron, effective field theory, hadronic parity violation, weak interaction
Created January 31, 2011, Updated February 19, 2017