A Deduction from Dirac Sea Model
  Whether the Dirac sea model is right is verifiable. Assuming the Dirac sea is a physical reality, we have one imagination that a negative energy particle(s) in the sea and a usual positive energy particle(s) will form a neutral atom. The features of the atom can be studied using the nonrelativistic reduction of the Bethe-Salpeter equation, especially for a two body system. This work is dedicated to discuss the bound state of spin-0 and spin-$\frac{\displaystyle 1}{\displaystyle 2}$ constituents. The study shows that an atom consisting of a negative energy particle $(e^-$ or $hc)$ and a positive energy particle $(u\overline{d}$ or $hc)$ has some features of a neutrino, such as spin, lepton number and oscillation. One deduction is that if the atom is a real particle, an atom $X$ consisting of two negative energy particles and a nucleus with double charges exists in nature, which can be observed in Strangeonium, Charmonium and Bottomonium decays $[s\overline{s}]$, $[c\overline{c}]$ and $[b\overline{b}]\rightarrow X \pi^-\pi^- e^+e^+~+~hc$ with $X$ invisible at KLOE, CLEOc, BESIII, Belle and BaBar. 
Jianguo Bian and Jiahui Wang
physics.gen-ph