Editing Beta decay (section)

===Baryon number is conserved===

<math display="block">B=\frac{n_q - n_{\bar{q}}}{3}</math>
where
* <math>n_q</math> is the number of constituent quarks, and
* <math>n_{\overline{q}}</math> is the number of constituent antiquarks.

Beta decay just changes [[neutron]] to [[proton]] or, in the case of positive beta decay ([[electron capture]]) [[proton]] to [[neutron]] so the number of individual [[quarks]] doesn't change. It is only the baryon flavor that changes, here labelled as the [[isospin]].

Up and down [[quarks]] have total isospin <math display="inline">I=\frac{1}{2}</math> and isospin projections
<math display="block">I_\text{z}=\begin{cases}
\frac{1}{2} & \text{up quark} \\
-\frac{1}{2} & \text{down quark}
\end{cases}</math>

All other quarks have {{math|1=''I'' = 0}}.

In general<!-- antiquarks are not expected! -->
<math display="block">I_\text{z}=\frac{1}{2} (n_\text{u} - n_\text{d})</math>