CONSERVATION RULES

We're at the end of this chapter now, and while that's incredibly sad and you're on the verge of bawling your eyes out I don't care - we're discussing conservation now, in terms of what's always conserved, what's sometimes conserved and what's never conserved. 

Quantities that are Conserved for Particular Interactions

Particles and antiparticles decay and interact and have particular properties - and they abide by the rules. The rules are as follows:

1) Conservation of Energy and Charge: This goes for all particles/ antiparticles/ toasters/ wombats etc. Charge and energy cannot be created or destroyed.Without this rule being followed, reactions simply wouldn't occur. 

2) a) Conservation of Lepton Numbers: This goes for particular particle-antiparticle interactions and decays. The total lepton number before a change is equal to the total lepton number after a change, for every lepton branch. Observe the table for the figures concerning the muon lepton number and the electron lepton number.

b) Conservation of Strangeness: This goes for particular particle-antiparticle interactions and decays. Strangeness is only conserved in the strong interaction - all changes involving the strong interaction lead to conservation. 

• Any hadron made up of a strange quark has a strangeness of -1, and a strangeness of +1 if made up of an antistrange quark. 
• Anything that is not a hadron has a strangeness of 0, which is 'strange' due to the numbers being crazy.

3) Conservation of Baryon Numbers: Some reactions have been observed but others haven't, yet all of the above rules are obeyed. In any reaction, the total baryon number is conserved. Remember that anything that isn't a baryon has a baryon number of 0 - so an antibaryon has a baryon number of -1 and a baryon of +1.

An up quark and an up antiquark annihilate each other - sad stuff, I know, but take a look at the quarks and antiquarks rearranging to form mesons. Beautiful. If the above baryon numbers are assigned to each of these guys, leptons have a baryon number of 0, quarks (+1/3) and antiquarks (-1/3). 

SO 0 = (+1 -1) and conservation of their baryon numbers has occured. Amazeballs, right? Like I said before, this heartwarming instance occurs in all reactions. 

It's been great having you guys here, but I'm afraid it's time for me to take my leave. I'll treasure the memories. Hopefully you're solid on this quarks and leptons stuff, and if you're not - that sucks. 

Keep on quarkin'.