# Homework Help: Decay of a roe meson

1. Jan 19, 2005

### K8181

I just started a class in particle physics this semester, and I really need help on one of our first homework problems. We are supposed to show that while the following decays are allowed:

roe(+) --> pi(0)pi(+)
roe(-) --> pi(0)pi(-)
roe(0) --> pi(+)pi(-)

the following decay is not allowed:

roe(0) --> pi(0)pi(0)

I am pretty sure the reason is that it violates a conservation law, but I don't know which one. We have barely touched on what quantities are conserved in lecture. I can see that charge is conserved in all cases, so no problem there.

We are also told that the roe meson is a spin 1 particle, so I think that should play a role. However, the part of quantum mechanics that dealt with angular momentum and spin was a bit treacherous for me. Any help is greatly appreciated.

2. Jan 19, 2005

### Integral

Staff Emeritus
This all sounds pretty fishy to me.... Oh perhaps you mean $\rho$ that is rho!

You might benifit by reading This thread.

3. Jan 19, 2005

### K8181

Fantastic! I am already familiar with LaTex.

4. Jan 19, 2005

### K8181

For anyone reading this thread, that link was just about using LaTex for math symbols...I still REALLY need help with this problem!!!

5. Jan 19, 2005

### vincebs

I'm not an expert in particle physics, but have you checked

1.) spin
2.) parity

I think rho mesons have both their quark and antiquark aligned, whereas pions have them antiparallel so one rho can't make two pions.

6. Jan 19, 2005

### K8181

From what I have deduced, I think the culprit is parity. Could you explain what you know about parity? I have always found it a mysterious concept.

7. Jan 19, 2005

### Astronuc

Staff Emeritus