# Particle interact with antiparticle

1. Feb 28, 2014

### jaysonxng

A particle meet its own antiparticle will annihilate and convert mass into energy. But what happen if a particle meets a antiparticle but not its own . For example, proton collided with anti neutron, etc..

2. Feb 28, 2014

### BvU

Hello Jay, and welcome to PF, where you posted in the homework area. This doesn't look like homework at all (If I am wrong, correct me and use the template provided under the "new thread" button).

Your question is difficult to answer at a suitable level, because I don't know what that level should be.

Basically, all kinds of things can happen if particles "meet". Especially if they "meet" with a lot of violence, as in head-to-head collisions at speeds close to the speed of light. In such collisions, high energy physicists study what are conserved quantities. Total energy (using E = mc2) and momentum are only a few. A lot of others fall under the common denominator "quantum numbers".

Point is that with enough energy, you can make almost anything -- in partice - antiparticle pairs. They can exchange constituents, or decay into other (lighter) stuff, etc.

Surf around in partice physics a little bit and welcome to this wonderful world!

3. Feb 28, 2014

### ChrisVer

They will interact in the same way every particle interacts with other particles, but they will not annihilate (at least not in low energies). At higher energies, the quark constituents will interact among themselves and annihilations are still possible (but that's because of your example).
Eg an electron with another antilepton, for example amtimuon, being fundamental (so far) will not be annihilated.

4. Feb 28, 2014

### BvU

Hello again. Things get murky if we don't agree on a suitable level. Are we talking Dan Brown here or are we in the realm of physics?

In the link I gave you you can find that a proton consists of three quarks (designated up, up and down for historical reasons. Not because they are oriented that way or anything; purely abstract. Short form: $uud$). Neutron is $udd$ so antineutron is $\bar u \bar d \bar d$. The bar denoting anti- . These guys "meet" and $u\bar u$ and $d\bar d$ are anihilation candidates; who knows you end up with $u\bar d$, a light particle called $\pi^+$ and a lot of energy left over for the kinetic energy with which it flies off all on its own ? Can't be because that does not conserve momentum, so some more stuff has to fly the other way. Gets complicated rapidly. See also this thread

This is what Chris alludes to when he says "quark constituents will interact among themselves". It's like throwing two handsful of marbles at each other: some marbles might collide and may chip, but most go through unscathed.