Editing Gluon (section)

=== Color singlet states <span class="anchor" id="Color singlet"></span> ===
The stable strongly interacting particles, including hadrons like the proton or the neutron, are observed to be "colorless". More precisely, they are in a "color singlet" state, and mathematically analogous to a [[singlet state|''spin'' singlet state]].<ref name="Griff">
{{cite book
 |author=David Griffiths
 |year=1987
 |title=Introduction to Elementary Particles
 |pages=280–281
 |publisher=[[John Wiley & Sons]]
 |isbn=978-0-471-60386-3
}}</ref> The states allow interaction with other color singlets, but not other color states; because long-range gluon interactions do not exist, this illustrates that gluons in the singlet state do not exist either.<ref name="Griff"/>

The color singlet state is:<ref name="Griff"/>
: <math>(r\bar{r}+b\bar{b}+g\bar{g})/\sqrt{3}.</math>

If one could [[Measurement in quantum mechanics|measure]] the color of the state, there would be equal probabilities of it being red–antired, blue–antiblue, or green–antigreen.