Maximally Minimal Preons in Four Dimensions
  Killing spinors of N=2, D=4 supergravity are examined using the spinorial geometry method, in which spinors are written as differential forms. By making use of methods developed in hep-th/0606049 to analyze preons in type IIB supergravity, we show that there are no simply connected solutions preserving exactly 3/4 of the supersymmetry. 
Jai Grover, Jan B. Gutowski and Wafic A. Sabra