This is obviously a duplicate of If matter and antimatter... However, it's now four to five years after a swarm of videos were made on this subject. At the time, there was a consensus that the LHC would soon be able to tell us if there's some asymmetry that might explain why matter and antimatter didn't completely annihilate each other in the first few seconds of BBN.
So what is the current state of this issue? Is there any theory that can explain how a photon could split into unequal parts of matter and antimatter? How big a problem is this?