Decay width $Z_1 \to l\bar l$: effects of the little Higgs model

Abstract

In the framework of the Little Higgs Model (LHM), we calculate the decay widths $\Gamma(Z_1 \to l\bar l)$ and $\Gamma_{inv}(Z_1 \to \nu\bar \nu)$ with corrections of QED and QCD. We analyze this with recent data from LEP and compute the contribution of the model. We find that the deviations of the decay width of reactions $Z_1 \to l\bar l$ and $Z_1 \to \nu\bar \nu$ from its SM value are relatively large in the parameter space preferred by the electroweak precision data. Furthermore, with reasonable free parameter values, the absolute value of the relative correction parameter $\delta\Gamma/\Gamma_{SM}$ is of $15%-50%$. The experimental measurement values could generate possible constraints on the free parameters of the LHM.