Theory of Conservation of Isotopic Spin fromd+dReactions

The theoretical cross section for the reaction $d+d\to {\mathrm{He}}^4+{\pi }^0$ has been calculated in the impulse approximation. It is assumed that the matrix element contains no isospin dependence which, due to conservation laws, would ordinarily prohibit pion production. The comparison of the theoretical and experimental cross sections for the reaction yields an upper limit of 6.5% for the amount of isospin nonconservation in strong interactions. A discussion of the effects of different ${\mathrm{He}}^4$ wave functions in the calculation is also included.