  A triple-product correlation in the radiative \beta-decay rate of neutrons or
of nuclei, characterized by the kinematic variable \xi\equiv
(\vec{l}_\nu\times\vec{l}_e)\cdot\vec{k}, where, e.g., n(p) \to p(p') +
e^-(l_e) + \bar{\nu}_e(l_\nu) + \gamma(k), can be generated by the
pseudo-Chern-Simons term found by Harvey, Hill, and Hill as a consequence of
the baryon vector current anomaly and SU(2)_{L} x U(1)_Y gauge invariance at
low energies. The correlation probes the imaginary part of its coupling
constant, so that its observation at anticipated levels of sensitivity would
reflect the presence of sources of CP violation beyond the standard model. We
compute the size of the asymmetry in n\to p e^- \bar\nu_e \gamma decay in
chiral effective theory, compare it with the computed background from
standard-model final-state interactions, and consider the new physics scenarios
which would be limited by its experimental study.

High Energy Physics - Phenomenology;Nuclear Theory