A beta particle has a relative mass of zero, so its mass number is zero. As the beta particle is an electron, it can be written as \(_{-1}^{~0}\textrm{e}\), and sometimes as \(_{-1}^{~0}\ ...

and the antineutrino move away from one another emitting the electron as a beta particle. The process is summarised by the equation: \(_0^1n\rightarrow_1^1p+_{-1}^{\,\,\,\,\,0}e+\overline{v} ...

What's less clear from a lot of these stories, though, is what this has to do with particle physics. For that matter, what does it even mean to talk about the electron having a shape? As ...