Why do different pions have different lifetimes?

[curious george]

I don't understand why the pi(+) has such a long lifetime compared to the pi(0). Can anyone give me a simple qualitatiive explanation of this?

 

[mathman]

pi(+) and pi(-) are quark-antiquark pairs, each of which is an up and a down. pi(0) is a quark-antiquark pair consisting of 2 ups or 2 downs. When a matter particle and its anti-matter opposite come together, they anihilate (sp?) each other very rapidly. This explanation is somewhat of an oversimplification, but you can see why the pi(0) has a much shorter lifetime.