[Physicist]

You might also give them a hint as to when antiparticles came into existence.

That would be right at the time that particles came into existence. What's wrong with the graphic?

I don't like the fact that they use "n" for neutrino and "t" for tau. The standard notation is that "n" stands for neutron and "t" for top quark.

[AndrewC]

That would be right at the time that particles came into existence

And what was "there" before that event?