COHERENT ELECTROPRODUCTION OF PIONS FROM HE-3

The He-3(e,e'pi(+))H-3 reaction is the simplest of the coherent charge d pion electroproduction reactions in nuclear physics. It is sensitive to the structure of the trinucleons, and can be studied with the high duty factor electron accelerators now available. It may also provide some insight for understanding the basic p(e,e' pi(+))n reaction if th e latter can be described within the constituent quark models of nucle ons. In this work, we calculate the ratio of p(e, e' pi(+))n and He-3( e, e' pi(+))H-3 cross sections for two kinematical conditions with inv ariant photon-nucleon mass W = 1160 and 1230 MeV, respectively. The fo ur important contributions to this ratio are identified as (i) the fin ite size (i.e., the form factor) of the trinucleons, (ii) the spin-iso spin correlations in the trinucleons, (iii) the finite range of the pr opagation of the struck proton, and (iv) the possible pion-nucleon fin al state interactions. Together they reduce the ratio of the cross sec tion to similar to 0.4 in this kinematic range.