Massless fermions and bound states in Kaluza-Klein theories

The authors consider fermions coupled minimally to Einstein-Cartan gravity in a seven-dimensional background space-time M/sub 4//sup 0/ circle times S/sup 3/ and use coordinates (x/sup μ/, y/sup m/), Greek indices go from 1 to 4 (M/sub 4//sup 0/) and small Latin indices from 5 to 7 (S/sup 3/). The authors only exhibit the ''internal'' component of the contorsion K/sub abc/ which is the only one which can have a non-zero vacuum expectation value (v.e.v.) compatibly with Poincare invariance