Higgs two-gluon decay and the top-quark chromomagnetic moment

We study the top quark chromomagnetic factor ${\kappa }_t$-dependence of the effective interaction ${\mathcal{L}}_{hgg}$ and apply the result to the case of Higgs two gluon decay rate ${\mathrm{\Gamma }}_{h\to gg}$. Perturbative standard model provides ${\kappa }_t<2$, and for the standard model value $\Gamma_{h\to gg}(\kappa_t)$issuppressedby9$\kappa_t= 2$. We further show that in the leading order ${\mathrm{\Gamma }}_{h\to gg}$ for ${\kappa }_t\simeq \pm 1.2$ can be very small due to complete cancelation between the top and bottom quark fluctuations. We discuss the extension of our results to ${\kappa }_t>2$ and consider potential paths to obtain experimental information for the $h\to gg$ rate.