On the tritium $\beta$- electrons energy shape

A series of high presicion atomic experiments was carried out last decade to get a better estimate for the electron (anti)neutrino mass $m_\nu$. The reaction to be observed is molecular tritium $\beta$- decay. The $m_\nu$ value serves as one of the tune parameters to fit $\beta$- electrons spectrum via reference theoretical one. The unexpected message consists of that parameter ${m^2_\nu}$ has to be fixed at some negative value to get best statistically reliable fit. Apart of some exotic scenarios suggested the problem remains open. In this paper we tried to reanalyze ground features of the final states spectrum (FSS) and its influence on the $\beta$- electrons spectrum. A new approach has been developed which gives some hints to make proper modifications to the tabulated FSS in the course of experimental fits.