Effective action of N=4 super Yang-Mills: N=2 superspace approach

Using the N = 2 off-shell formulation in harmonic superspace for N = 4 supe r Yang-Mills theory, we present a representation of the one-loop effective action which is free of so-called coinciding harmonic singularities and adm its a straightforward evaluation of low-energy quantum corrections in the f ramework of an N = 2 superfield heat kernel technique. We illustrate our ap proach by computing the low-energy effective action on the Coulomb branch o f SU(2) N = 4 super Yang-Mills. Our work provides the first derivation of t he low-energy action of N = 4 super Yang-Mills theory directly in N = 2 sup erspace without any reduction to N = 1 superfields and for a generic backgr ound N = 2 Yang-Mills multiplet. (C) 2001 Published by Elsevier Science B.V .