Charge Symmetry Violation in pnto d π⁰ as a Test of Chiral Effective Field Theory

Chiral effective field theory predicts a specific charge symmetry violating amplitude for pion production. This term is shown to provide the dominant contribution to the forward-backward asymmetry in the angular distribution for the reaction $pn\to d\pi^0$, for reasonable values of the mass difference between down and up quarks, $\delta m_N$. Using a value $\delta m_N\approx$ 3 MeV leads to a prediction of a 10 standard deviation effect for a TRIUMF experiment.