K-l3 and pi(e3) transition form factors

K-l3 and pi(e3) transition form factors are calculated as an application of Dyson-Schwinger equations. A heuristic one-parameter model of the quark-W-boson vertex is used to highlight their sensitivity to the form of this vertex, The K-l3 form factors, f(+/-)(K), are approximately linear on t is an element of [m(e)(2), m(mu)(2)] and f(+)(K')(0) similar to f(-)(K')(0).f(-)(K)(0) is a measure of the Euclidean constituent-quark mass ratio: M-s(E)/M-u(E). In the isospin symmetric limit: -f(+)(pi)(0) = F-pi(t), the electromagnetic pion form factor, and f(-)(pi) (t) = 0. (C) 1997 Published by Elsevier Science B.V.