IRFP conformal dynamics in many flavor lattice QCD in the light of thermal chiral phase transition
Novel (pre-)conformal phase associated with the infra-red fixed point (IRFP) is anticipated to emerge due to non-perturbative interactions in asymptotically free non-Abelian gauge theories when the number of fermion species (N_f) exceeds a critical value (N_f = N_f*). The pre-conformal dynamics has been advocated as a basis for strongly interacting mechanisms of electroweak symmetry breaking (walking technicolor scenario). Lattice Monte-Carlo simulations are now expected to provide a solid theoretical base for this new class of strongly interacting gauge theories. We first briefely review the general motivation to considering the IRFP (pre-) conformality. Then, we particularly investigate the IRFP conformality in colour SU(N_c=3) gauge theory with a variable number N_f of fundamental fermions by using lattice Monte-Carlo simulations. We evaluate the thermal chiral phase transition as a function of N_f, and propose three independent estimates of N_f*, which are consistent to each other within error-bars. This strongly indicates the existance of the conformal phase in large N_f region.