Forbidden and invisible Z boson decays in covariant theta-exact noncommutative standard model

Abstract

The triple neutral gauge boson and direct U(1)_Y-neutrino interactions, being absent in ordinary field theory, can arise quite naturally in noncommutative gauge field theories. Using non-perturbative methods and a Seiberg-Witten map based covariant approach to noncommutative gauge theory, we have found theta-exact expressions for both interactions, thereby eliminating previous restrictions to low-energy phenomena. In particular we obtain for the first time the covariant, theta-exact, triple neutral gauge boson interactions within the noncommutative Standard Model gauge sector including an additional gauge-field deformation freedom. Finally we discuss implications for Z->2gamma and Z->neutrino-pair decays, and show that our results behave quite reasonably throughout all interaction energy scales.

Comments: Major revised version, containing 9 pages and 3 figures, to be published in Journal of Physics G: Nuclear and Particle Physics. Addition of a gauge-field-deformation freedom. Consequently added a number of important equations and references, changed Figs 1,2,3, and changed introduction and discussion sections