There are various possibilities depending on the energy of the particles.
An antineutron has valence quarks bar{u}, bar{d}, bar{d}. A proton has valence quarks u, u, d. There are two quark-antiquark pairs here: u + bar{u} and d + bar{d}. In the simplest case, these annihilate electromagnetically: each pair produces two photons. The leftover u + bar{d} becomes a positively-charged pion.
The pi+ will most often decay to an antimuon + muon neutrino, and the antimuon will most often decay to a positron + electron neutrino + muon antineutrino. (It should be noted that muons have a relatively long lifetime, so the antimuon is likely to travel a long distance before decaying, depending on its energy. The pi+ decays much more quickly.)
There are many other paths the interaction can take, though. The quark-antiquark pairs can interact through the strong force, producing more hadrons. They can also interact through the weak force, producing other hadrons or leptons. And, of course, there are different alternative decay paths for the annihilation products that will occur in some fraction of events. As the energy of the initial particles increases, more final states become available. Energy can be converted to mass, so more energy means heavier products are allowed.
Edit: thanks to wedrifid for the reminder of LaTeX image embedding.
An antineutron has valence quarks u¯, d¯, d¯. (The bar should really be directly above the letter to indicate antiparticles, but Markdown does not have an overline syntax as far as I know.)
Another approach is to use actual combining overlines U+0305: u̅, d̅, d̅. This requires no markup or external server support; however, these Unicode characters are not universally supported and some readers may see a letter followed by an overline or a no-symbol-available mark.
There are various possibilities depending on the energy of the particles.
An antineutron has valence quarks bar{u}, bar{d}, bar{d}. A proton has valence quarks u, u, d. There are two quark-antiquark pairs here: u + bar{u} and d + bar{d}. In the simplest case, these annihilate electromagnetically: each pair produces two photons. The leftover u + bar{d} becomes a positively-charged pion.
The pi+ will most often decay to an antimuon + muon neutrino, and the antimuon will most often decay to a positron + electron neutrino + muon antineutrino. (It should be noted that muons have a relatively long lifetime, so the antimuon is likely to travel a long distance before decaying, depending on its energy. The pi+ decays much more quickly.)
There are many other paths the interaction can take, though. The quark-antiquark pairs can interact through the strong force, producing more hadrons. They can also interact through the weak force, producing other hadrons or leptons. And, of course, there are different alternative decay paths for the annihilation products that will occur in some fraction of events. As the energy of the initial particles increases, more final states become available. Energy can be converted to mass, so more energy means heavier products are allowed.
Edit: thanks to wedrifid for the reminder of LaTeX image embedding.
Piece of cake:
bar{u},bar{d},bar{d}
Another approach is to use actual combining overlines U+0305: u̅, d̅, d̅. This requires no markup or external server support; however, these Unicode characters are not universally supported and some readers may see a letter followed by an overline or a no-symbol-available mark.
If you wish to type this and other Unicode symbols on a Mac, you may be interested in my mathematical keyboard layout.