Polarization effects in the reactions p + 3He → π+ + 4He, π+ + 4He → p + 3He and quantum character of spin correlations in the final (p, 3He) system

Abstract

The general consequences of T invariance for the direct and inverse binary reactions a + b → c + d, c + d → a + b with spin-1/2 particles a, b and unpolarized particles c, d are considered. Using the formalism of helicity amplitudes, the polarization effects are studied in the reaction p + 3He → π+ + 4He and in the inverse process π+ + 4He → p + 3He. It is shown that in the reaction π+ + 4He → p + 3He the spins of the final proton and 3 He nucleus are strongly correlated. A structural expression through helicity amplitudes, corresponding to arbitrary emission angles, is obtained for the correlation tensor. It is established that in the reaction π+ + 4He → p + 3He one of the “classical” incoherence inequalities of the Bell type for diagonal components of the correlation tensor is necessarily violated and, thus, the spin correlations of the final particles have the strongly pronounced quantum character.