A positive pion is an up and an anti-down. A negative pion is a down and an anti-up. What's a pion with an electrical charge of 0?
What are the weak hypercharge and weak isospin quantum numbers of the helicity states of the $W^\pm$ and $Z^0$ bosons? The W boson is a spin-1 massless particle. Consequently it has three helicity ...
The Wikipedia article on deep inelastic scattering suggests that the experiment shows baryons have three point of deflections (corresponding to three quarks) and mesons have two points of deflection. ...