We consider Yang-Mills theories formulated on a non-commutative space-time
described by a space-time dependent anti-symmetric field θμν(x).
Using Seiberg-Witten map techniques we derive the leading order operators for
the effective field theories that take into account the effects of such a
background field. These effective theories are valid for a weakly
non-commutative space-time. It is remarkable to note that already simple models
for θμν(x) can help to loosen the bounds on space-time
non-commutativity coming from low energy physics. Non-commutative geometry
formulated in our framework is a potential candidate for new physics beyond the
standard model.Comment: 22 pages, 1 figur