Nonstandard Parafermions and String Compactification
  Nonstandard parafermions are built and their central charges and dimensions are calculated. We then construct new N=2 superconformal field theories by tensoring the parafermions with a free boson. We study the spectrum and modular transformations of these theories. Superstring and heterotic strings in four dimensions are then obtained by tensoring the new superconformal field theories along with some minimal models. The generations and antigenerations are studied. We give an example of the $1^2(5,7)$ theory which is shown to have three net generations. 
Andrei Babichenko and Doron Gepner
hep-th hep-ph math-ph math.MP