Baryon Asymmetry: Why Does Matter Exist? (String Theory)

After the big bang, raw energy was transformed into matter. If the energy of the early universe had cooled into equal amounts of matter and antimatter, these different forms of matter would have annihilated each other, leaving no matter in the universe. Instead, there was substantially more matter than antimatter, enough so that when all the antimatter had been annihilated by matter, enough matter was left to make up the visible universe. This early difference between matter and antimatter is called baryon asymmetry (because regular matter, made up of baryons, is called baryonic matter).
The laws of physics provide no clear reason why the amounts of matter and antimatter wouldn’t have been equal, so presumably a theory of everything would explain why the dense energy of the early universe tended to favor — even if only by a little bit — matter over antimatter.