North-Holland U(1)L ® U(1)R SYMMETRIC YUKAWA MODEL IN THE SYMMETRIC PHASE

The lattice regularized U(1)ß ® U(1)R symmetric scalar fermion model with explicit mirror fermions is investigated in the phase with unbroken symmetry. As a first part of a non-perturba-tive investigation, in the present work numerical Monte Carlo calculations with dynamical fermions are performed on 43 x 8, 6; x 12 and 8 3 x 16 lattices near the expected perturbative gaussian fixed point, in order to study the cutoff-dependent upper limit on the renormalized scalar quartic- and Yukawa-couplings. The bare Yukawa coupling of the mirror fermion is fixed at zero, which is near the region of parameter space where in the broken phase decoupling of the mirror fermion is expected. Lattice perturbation theory and fermion hopping parameter expansion is exploited for supporting the numerical simulations. 1