Quark model description of quasi-elastic pion knockout from the proton at JLAB

Abstract The interference term between s - and t -pole contributions to the p ( e , e ′ π + ) n cross section is evaluated on the basis of the constituent quark model. It is shown that the contribution of baryon s -poles can be modeled by a nonlocal extension of the Kroll–Ruderman contact term. This contribution is in a destructive interference with the pion t -pole that is essential to improve the description of recent JLab data at the invariant mass W = 1.95 GeV . Some predictions are made for a new JLab measurement at higher values W = 2.1 – 2.3 GeV and Q 2 centered at 1.6 and 2.45 GeV 2 / c 2 .