Electric Charge Q Electric charge is conserved in all interactions. Hence baryons , Mesons Baryon number is conserved in Strong, EM and Weak Interactions. Since the proton is the lightest baryon it cannot decay if B is conserved. If the Parity operator P acts on a wavefunction then but i.e. and . One can show that a state with angular momentum l has parity associated with it.
Parity is multiplicative.
The Parity of a composite system is equal to the product of the individual parities. For Bosons the parity of the antiparticle is the same as the parity of the particle. We label particles by meaning Spin S Spin is an intrinsic property of all particles. It is just like angular momentum but is a quantum mechanical effect. The proton and neutron form an doublet with for the proton and for the neutron.