Constraints on neutrino parameters and doubly charged Higgs particles in the $e^-e^- \to W^-W^-$ process

Doubly charged Higgs s-channel resonances are analyzed in the $e^-e^- \to W^-W^-$ process. In our analysis recent stringent constraint on an effective neutrino mass $<m_{\nu}>$ coming from neutrinoless double-$\beta$ decay is implemented. It is shown that due to a very restrictive limit on $<m_{\nu}>$ the doubly charged Higgs resonance predicted by the Standard Model with additional Higgs triplets is below the detection limit. For the same reason also the $\Delta_L^{--}$ resonance can not be visible in the framework of the conventional Left-Right symmetric model. The situation is quite different for the $\Delta_R^{--}$ pole and large signal is possible here. Contributions of the s, t and u channels to the cross section around the $\Delta_R^{--}$ peak are also discussed.