Finite size scaling of conformal theories in the presence of a near-marginal operator

Abstract

The slowly evolving gauge coupling of gauge-fermion systems near the conformal boundary makes numerical investigations of these models challenging. We consider finite size scaling and show that in the case of 12-flavor SU(3) gauge theory this often-used technique leads to inconsistent results if the leading order scaling corrections are neglected. When the corrections are included the results become consistent not only between different operators but even when data obtained at different gauge couplings or with different lattice actions are combined. Our results indicate that the SU(3) 12-fermion system is infrared conformal with mass anomalous dimension ${\ensuremath{\gamma}}_{m}=0.235(15)$.