Chirality Changing Phase Transitions in 4d String Vacua

Abstract

We provide evidence that some four-dimensional N=1 string vacua with different numbers of generations are connected through phase transitions. The transitions involve going through a point in moduli space where there is a nontrivial fixed point governing the low energy field theory. In an M-theory description, the examples involve wrapped 5-branes leaving one of the ends of the world.

16 pages, harvmac big, minor error in section 3.3 corrected