# Attraction and repulsion for identical particles

1. Mar 11, 2004

### Janitor

I briefly scanned back through old topics in this part of the Physics Forum, and didn't see any that seemed to bring up this exact issue, so...

I have read in several popularizations of physics that the exchange of bosons between a pair of identical particles will cause attraction if the boson has even integer spin, and repulsion if the boson has odd integer spin. Is there any sort of reasonably simple explanation?

[Example: a pair of electrons repel one another under the exchange of spin 1 (odd integer) virtual photons.]

Last edited: Mar 12, 2004
2. Mar 12, 2004

### arivero

I have never seen an intuitive argument for it. The derivation usually calculates first order diagrams, then reverses Born approximation to obtain an equivalent potential. It can be seen that the potential gets a positive sign for spin 1 (generically, odd) and negative for spin 0. Thus one is repulsive, the other is attractive.

Last edited: Mar 12, 2004
3. Mar 12, 2004

### Janitor

Thanks, arivero.

I know that the PCT Theorem can be proved in a pretty airtight way--though it is not a very simple argument to follow. And around the start of World War II, Pauli showed in a paper (in the Physical Review, if I remember) that certain contradictions would arise if the connection between spin classes (integer vs. half-odd integer in this case) and the exclusion principle were not to hold. I was hoping something similarly elegant might be the case for the attraction vs. repulsion connection to boson spin.

Does the method you speak of work out the same way for higher order diagrams as well?

4. Jul 22, 2008

### yoyoq

5. Jul 22, 2008

### ZapperZ

Staff Emeritus
I hope you realize that you are responding to a thread that had the last post in 2004.

Zz.

6. Jul 22, 2008

### arivero

Well, at least a 50% of the participants of the thread are still around.