Fig. 7.

95% CL limit on $C_{\mathrm{Z}\mathrm{H}}/\Lambda$ and $C_{\mathrm{a}\mathrm{H}}/{\Lambda }^2$ as function of $m_{\mathrm{a}}$. Black curves are the expected upper limits, with one and two standard-deviation bands shown in green and yellow, respectively. The solid black curves represent the observed upper limits. The grey band corresponds to the excluded region around the $\mathrm{b}\overline{\mathrm{b}}$ bound states of ${\rm Y}$