Signals for Non-Commutative QED in eγ and γγ Collisions

We study the effects of non-commutative QED (NCQED) in fermion pair production, γ + γ → f + f̄ and Compton scattering, e + γ → e + γ. Noncommutative geometries appear naturally in the context of string/M-theory and gives rise to 3and 4-point photon vertices and to momentum dependent phase factors in QED vertices which will have observable effects in high energy collisions. We consider ee colliders with energies appropriate to the TeV Linear Collider proposals and the multi-TeV CLIC project operating in γγ and eγ modes. Non-commutative scales roughly equal to the center of mass energy of the ee collider can be probed, with the exact value depending on the model parameters and experimental factors. However, we found that the Compton process is sensitive to ΛNC values roughly twice as large as those accessible to the pair production process. PACS numbers: 12.60.-i, 13.40.-f, 12.90.+i Typeset using REVTEX