QED with a large number N of massless fermionic degrees of freedom has a
conformal phase in a range of space-time dimensions. We use a large N
diagrammatic approach to calculate the leading corrections to CTβ, the
coefficient of the two-point function of the stress-energy tensor, and CJβ,
the coefficient of the two-point function of the global symmetry current. We
present explicit formulae as a function of d and check them versus the
expectations in 2 and 4βΟ΅ dimensions. Using our results in higher even
dimensions we find a concise formula for CTβ of the conformal Maxwell theory
with higher derivative action FΞΌΞ½β(ββ2)2dββ2FΞΌΞ½. In d=3, QED has a topological symmetry current, and we calculate the
correction to its two-point function coefficient, CJtopβ. We
also show that some RG flows involving QED in d=3 obey CTUVβ>CTIRβ and discuss possible implications of this inequality for the
symmetry breaking at small values of N.Comment: 29 pages, 9 figures. v3: minor improvements, references adde