A Proton anti-proton pair and CP eigenstate

[merrypark3]

p\bar{p} pair is a CP eigenstate?

As p and \bar{p} are fermions (the pair is assumed to be at S-state), the pair seems to be C's eigenstate with eigenvalue of -1.

As they have opposite intrinsic parity, the pair state seems to be P's eigenstate with eigenvalue -1. Then isn't it CP eigenstate with eigenvalue of 1?

But why the p\bar{p} pair cannot produce K_S or K_L but only \bar{K}^0?

 

[Vanadium 50]

pbar-p pair is a CP eigenstate?

Not necessarily. The rest of the message assumes this, so there's no point in commenting on it.