Understanding Antimatter Annihilation: Levels and Possibilities"

[Big-Daddy]

At what level does annihilation occur?

For example, if I've got an up quark and an anti-up quark, they can annihilate. If I've got a proton (uud) and anti-proton (anti up, anti up, anti down), they can annihilate. What if I mix a neutron (down, down, up) with an anti-proton (anti up, anti up, anti down)? Can we get the annihilation of the neutron's down quark(s) with the anti-proton's anti-down quark, or of the neutron's up quark with the anti-proton's anti-up quark(s)?

What if we have an anti-H atom (anti-proton and positron, I guess) - obviously this will annihilate with an H atom (proton and electron), but will the anti-proton annihilate individually with a proton, or the positron annihilate individually with an electron, to leave behind just a positron or an anti-proton respectively? Will an anti-H atom annihilate with an H₂ molecule, given that the H₂ electrons are taken up in a bonding pair? What will be left afterwards then?

 

[nst.john]

I have an idea!

I only have a high school regents physics understanding about all of this but bear with me. Like in chemistry how when two elements bond together, they become something totally different then their original forms, maybe this is the same for quarks, an up up and down quark make a proton, something maybe different from their original properties, so I believe if a neutron and an anti-proton were to collide, complete annihilation would not occur because the new bonded product does not act the same as its simpler "ingredients" would alone.

 

[Viracocha]

all sorts of things can happen, but it really depends on the collision itself. If you had enough energy you'd be able to collide the neutron and anti-proton and get annihilation (although it also depends on pure probability), which would then form a couple of mesons from the free quarks

Same goes for the H, if you had enough energy to get a collision you could easily get H, anti-H, annihilation. This extends to the H2, the molecular form doesn't matter much on the subatomic scale.

 

[Big-Daddy]

the molecular form doesn't matter much on the subatomic scale.

Are you sure this is true?

 

[Viracocha]

It's true as far as I know, molecules are just more compact clusters of atoms. Molecules are much larger than atoms and particle interactions don't really do much on scales larger than atoms. You can have interactions that take place in a lone proton/neutron of a heavy element without even effecting other protons/neutrons (for example, radioactive decay), so I can't imagine that a molecular form would matter much.