CP transformation, charge conjugation and antimatter

[Gene Naden]

Many discussions cite CP transformation as the exchange of particles for anitparticles. But other places it says that charge conjugation alone is sufficient to turn a particle into its antiparticle. So, the question is, when you exchange particles for anitparticles, is it a CP transformation or just charge conjugation?

 

[mfb]

Changing particles and antiparticles is C transformation.

Many discussions cite CP transformation as the exchange of particles for anitparticles.

Who does this?

 

[Gene Naden]

Well, maybe I was mistaken about sources that say it explicity. Upon reviewing the WIkipedia article on CP asymmetry, it does identify the antiparticle transformation as being only charge conjugation.

But Wikipedia says CP violation plays an "important role" in explaining matter-antimatter asymmetry and the Sakharov conditions for matter-antimatter asymmetry include CP violation. So why the emphasis on CP violation if it is C asymmetry that is relevant.

 

[mfb]

C violation alone doesn't give you any process that would favor matter over antimatter, as there is no "preferred parity" - with C violation but CP conservation every process that produces matter would also produce antimatter in the same amount, just with different angular distributions.

 

[Gene Naden]

Thank you, that is very helpful.