Raul Horvat, Amon Ilakovac, Dalibor Kekez, Josip Trampetic, Jiangyabg You
Triple neutral gauge boson and direct photon-neutrino interactions arise quite naturally in noncommutative gauge field theories. Such couplings are absent in ordinary field theory and imply experimental lower bounds on the energy scale Lambda_NC ~ |theta|^{-1/2} of spacetime noncommutativity. Using non-perturbative methods and a Seiberg-Witten (SW) map based covariant approach to noncommutative gauge theory, we obtain theta-exact expressions for the interactions, thereby eliminating previous restrictions to low-energy phenomena. We discuss implications for Z -> gamma gamma and Z -> nu barnu decays, and show that our results behave reasonably throughout all interaction energy scales. Constraining the invisible Z width for this kind of new physics to be under around 1 MeV, one produces Lambda_NC ~ 140 GeV. Although with the current experimental upper limit on the branching ratio BR(Z -> gamma gamma) the obtained bound on Lambda_NC is of the same order of magnitude, we have demonstrated how the expected improvement on the branching ratio from the LHC experiments may significantly strengthen the bound on the spacetime noncommutativity.
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http://arxiv.org/abs/1204.6201
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