Worldline description of the Isgur-Wise function
  An effective field theoretic description of the Isgur-Wise function in heavy-meson transitions is presented which emulates soft interactions by a fermion worldline with an infinitesimal self-intersecting loop. A point-splitting regularization technique is used, which replaces pointlike worldlines by ``ribbons'' in the sense of Witten. The calculated vertex function is correctly normalized, does not depend on the heavy-quark mass, and complies with different sets of recent experimental data of the ARGUS and CLEO collaborations. 
N. G. Stefanis, A. I. Karanikas, and C. N. Ktorides