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The three complex form factors entering the ⌬˜N␥* vertex are calculated to O( 3 ) in the framework of a chiral effective theory with explicit ⌬(1232) degrees of freedom included. It is shown that the low q 2 behavior of the form factors is governed by N, ⌬ loop effects. Predictions are given for the q 2 dependence of the three transition multipoles M 1(q 2 ), E2(q 2 ), C2(q 2 ). Furthermore, the role of the presently unknown low energy constants that affect the values of the multipole ratios EMR(q 2 ) and CMR(q 2 ) is elucidated.

We calculate Sudakov-type form factors for isolated spin-1/2 particles (fermions) entering non-Abelian gauge-field systems. We consider both the on-and the off-mass-shell case using a methodology which rests on a worldline casting of field theories. The simplicity and utility of our approach derives from the fact that we are in a position to make, a priori, a more transparent separation (factorization), with respect to a given scale, between short-and long-distance physics than diagramatic methods.

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