MONTE-CARLO RENORMALIZATION-GROUP STUDY OF GAUGED RP2 SPIN MODELS IN 2-DIMENSIONS

The 2D RP2 gauge model is studied using the Monte-Carlo Renormalizatio n Group (MCRG). We confirm the first-order transition reported in [1] ending in a critical point associated with vorticity. We find evidence for a new renormalized trajectory (RT) which is responsible for a cro ss-over from the vortex dominated regime to the O(3) regime as the cou pling is reduced. Near to the cross-over region a good signal for scal ing will be observed in RP2 but this is illusory and is due to the pro ximity of the RT. We suggest that this is the origin of the 'pseudo'-s caling observed in [2]. We find that the continuum limit of RP2 is con trolled by the O(3) fixed point.