Jump processes related to the two dimensional dirac equation

In four papers [ I ] wr i t ten from 1963 to 1968, Symanzik indicated how to f i t Feynman's formal approach [2] to Bose quantum f i e l d theory into a framework making possible mathematical control . The Euclidean strategy has become a central tool in the mathematical analysis of quantum f i e l d theory, which s impl i f ies exact calculat ions and estimates of functional integrals (see e.g. [3] and the reference therein). The der ivat ion of a path integral representation for the wave function of spin part i c les was solved by Feynman and Hibbs [4, ex. 2-6] and rev is i ted many times [5] , [6] , [7] , [8] , [9] , [10]. Recently, a p robab i l i s t i c solut ion was derived for the Pauli equation [11], [12] r [13] and an approach based on stochastic mechanics was formulated [14], [15].