Probing the scale of non-commutativity of space

Abstract

Examining quantum electrodynamics in non-commutative (NC) spaces along with composite operators in these spaces, we show that i) any charge g for a fermion matter field is allowed provided the basic NC photon-photon coupling is g, however no other multiples of g are permitted and ii) composite operators do not have a simple transformation which can be attributed to the effective total charge of the composite particle. Taken together these results place a limit on the scale of non-commutativity to be at most smaller that current LHC limits for compositeness. Furthermore, they also suggest that a substructure at still smaller scales is needed if such spaces are to be a physical reality.