Worldsheet supersymmetry (or spacetime SUSY via GSO projection) eliminates the tachyon and drops critical dimension from 26 to 10. Five consistent 10D vacua (type I, IIA, IIB, two heterotic) related by dualities.
Worldsheet supersymmetry (or spacetime SUSY via GSO projection) eliminates the tachyon and drops critical dimension from 26 to 10. Five consistent 10D vacua (type I, IIA, IIB, two heterotic) related by dualities.