Constraints from CMB on Spacetime Noncommutativity and Causality Violation

Understand

We try to constrain the noncommutativity length scale of the theoretical model given in Ref.

• [1] using the observational data from ACBAR, CBI and five year WMAP.
• The noncommutativity parameter is not constrained by WMAP data, however ACBAR and CBI data restrict the lower bound of its energy scale to be around 10 TeV.
• We also derive an expression for the amount of non-causality coming from spacetime noncommutativity for the fields of primordial scalar perturbations that are space-like separated.