Constraints from the cosmic microwave background on spacetime noncommutativity and causality violation

We try to constrain the noncommutativity length scale of the theoretical model given in [E. Akofor, A. P. Balachandran, S. G. Jo, A. Joseph, and B. A. Qureshi, J. High Energy Phys. 05 (2008) 092.] using the observational data from ACBAR, CBI and 5 yr WMAP. ACBAR and CBI data restrict the lower bound of the noncommutativity energy scale to be around 10 TeV. We also derive an expression for the amount of noncausality coming from spacetime noncommutativity for the fields of primordial scalar perturbations that are spacelike separated.