# Poin and rho almost the same

1. Feb 22, 2004

### Phalanx

pion u,anti-d spin = 0 mass = 0.140
rho u,anti-d spin = 1 mass = 0.770

so... are pion and rho the same or related? is the difference in spin what accounts for the difference in the mass or vice versa?

2. Feb 22, 2004

### meteor

I think that the difference lies in the binding energy

3. Feb 23, 2004

### Norman

The difference is the spin. The rho belongs to the class of mesons called "vector mesons" and the pions belong to the class deemed "pseudo scalar" mesons. These names just group together the mesons based upon their spin. I suppose you could think of the rho as being some kind of resonant state of the pion like you can think of the Delta as being a kind of resonant state of the nucleon. The main difference between the rho and the pion (other than the spin), from my point of view, is how they decay. The charged pions decay via the weak channel (while the neutral pion decays electromagnetically) but the rho appears to decay through the strong interaction.
hope this helps.
Norm