Scheme-Independent Calculation of $\gamma_{\bar\psi\psi,IR}$ for an SU(3) Gauge Theory

Abstract

We present a scheme-independent calculation of the infrared value of the anomalous dimension of the fermion bilinear, $\gamma_{\bar\psi\psi,IR}$ in an SU(3) gauge theory as a function of the number of fermions, $N_f$, via a series expansion in powers of $\Delta_f$, where $\Delta_f=(16.5-N_f)$, to order $\Delta_f^4$. We perform an extrapolation to obtain the first determination of the exact $\gamma_{\bar\psi\psi,IR}$ from continuum field theory. The results are compared with calculations of the $n$-loop values of this anomalous dimension from series in powers of the coupling and from lattice measurements.