The ordinary matter of the universe is composed of protons, neutrons, and their combinations in nuclei, as well as their surrounding electrons making up atoms. The connection with quarks is that the proton contains two u quarks and one d quark with a +1 charge, while the neutron contains one u quark and two d quarks, for a neutral or zero charge.
The elementary particles start with the quarks, which are strongly interacting with each other through the gluons g. The upper row (u, c, and t) are called up type quarks and are charged +2/3 of the magnitude of the electron’s charge. The bottom row are called down type quarks (d, s and b) and are charged -1/3 of the magnitude of the electron’s charge. The quarks also have weak and electromagnetic interactions.
The leptons are the negatively charged electron, and its heavier look alikes, the muon and the tau, and their related neutrinos ν_e, ν_μ, and ν_τ. They only have electromagnetic and weak interactions.
All of the quarks and charged leptons have their antiparticles also, which are opposite charged, but have the same mass.
The particle called gamma is the photon or the carrier of electromagnetic force.
Beta decay is the heavier neutron decaying to a proton and releasing an electron, and an electron anti-neutrino (ν_e with a bar over it). At a quark level, the charge changing weak interactions let a d quark in the neutron decay to a u quark in the proton by giving off a virtual negative W¯ boson, and the W¯ becomes an electron plus an anti electron neutrino. In the diagram, the time t is increasing in the upward direction.
The positive and negative W bosons carry out the charge changing weak interactions, while the neutral Z boson carries out the neutral current weak interactions.
We now see that the ordering of the leptons into the two rows shows that the electron is always associated with the electron neutrino in the charged weak interaction, and the same for the muon and the tau and their respective neutrinos.
The ordering of the up and down quarks in the same column are also their association under the charged weak interactions.
