Why Don't Quarks and Antiquarks Annihilate Each Other in Mesons?

[Phalanx]

Project due tommorrow please help<-----------

hello, i am doing a project on the standard model for my school, i have two questions,

1)mesons are made of a quark and an anitquark, why don't they annihalate each other?

2)what is residual strong force all about, if each proton and neutron are colour neutral then why does the nucleus stick together?

3)also what are neutrinos, and i mean all of them tau electron and muon, and what do they do and how are they made

4)what is the point in spin? i have read many websites about this but none of them explain how different spins make different particles act towards each other.

 

[Andy]

Cant help with the questions, but don't leave it soo long before you ask for help next time, the more time you leave yourself the better responses you will get and the more you will understand them.

 

[JasonRox]

I would like how spin works. I've heard about and all, but I'm not quite sure what it is. I've heard that they are not actually spinning; is this true?

You can post it later, or PM some advice.

 

[Phalanx]

now i have one more question if you don't mind.

How does elecromagnetic force get 'mediated' by a photon, are charged atoms just constantly emmitting photons in all directions? and why when a photon hits an atom with an opposite charge is it attracted?

 

[chroot]

Originally posted by Phalanx
1)mesons are made of a quark and an anitquark, why don't they annihalate each other?

They do, eventually. A meson may survive for only a very short time before that happens.

2)what is residual strong force all about, if each proton and neutron are colour neutral then why does the nucleus stick together?

When you're far away from the proton, it appears completely color-neutral. When you get close enough, though, you start to notice that there are three "centers" of color inside it. When you're really close, the quark closest to you dominates.

It's very much like electrostatic dipoles. Take molecules of salt, for example: NaCl. When you're far enough away from the salt molecule, it just appears to be a neutral molecule. When you get close enough, you realize there's a positive end and a negative end.

3)also what are neutrinos, and i mean all of them tau electron and muon, and what do they do and how are they made

The electron, muon, and tau are NOT neutrinos -- they are massive leptons. Each has a complementary neutrino -- called the electron neutrino, muon neutrino, and tau neutrino. The neutrinos are created in order to preserve lepton number, basically. When a neutron decays, for example, it decays into a proton, electron, and electron anti-neutrino.

4)what is the point in spin? i have read many websites about this but none of them explain how different spins make different particles act towards each other.

Spin is just another quantum number, which doubles the number of states a quantum system can have. It may or may not be reasonable to consider spin as an analogy to classical rotation. Generally, it's not.

- Warren

 

[garytse86]

Spin is just another quantum number, which doubles the number of states a quantum system can have. It may or may not be reasonable to consider spin as an analogy to classical rotation. Generally, it's not.

I thought in an orbital two different electrons have opposite spin in order to conteract the electrostatic repulsive force?

Gary