  U(1) gauge theory on non-commutative Minkowski space-time in the Feynman-'t
Hooft background gauge is studied. In particular, UV divergences and
non-commutative IR divergent contributions to the two, three and four-point
functions are explicitly computed at one loop. We show that the negative sign
of the beta function results from paramagnetism --producing UV charge
anti-screening-- prevailing over diamagnetism --giving rise toUV charge
screening. This dominance in the field theory setting corresponds to tachyon
magnification dominance in the string theory framework. Our calculations
provide an explicit realization of UV/IR mixing and lead to an IR
renormalization of the coupling constant, where now paramagnetic contributions
produce screening and diamagnetic contributions anti-screening.
