system
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human
How can Antiprotons annihilate with Neutrons?

I thought annihilation requires a particle and its specific anti-particle but I read in a book about antimatter that antiprotons annihilate with neutrons. How so?
gpt
Hadrons are made of quarks. A neutron has valence quark content of udd and a proton has valence quark content of uud. So an antiproton has antiup and antidown quarks which can annihilate with up and down quarks in a neutron. They can’t fully annihilate each other; there will still be some quarks in the final state (probably in the form of pions).