# Pi mesons

1. Apr 15, 2004

### EIRE2003

A quark and an anti - quark combine to form a meson. The pi-meson family is made up of u and d quarks only. A pi-meson can be positively, negatively or neutrally charged.
Give the quark composition of each of the 3 types of pi-meson.

The positively charged pion has a composition of an anti down quark and an up quark.

The neutrally charged pion has a composition of an anti-up quark and an up quark + an anti down quark and a down quark / square root of 2. What does this mean??

What is the composition of the negatively charged pi meson?

Is it these 3 types of mesons it is asking me for the compositions of?

2. Apr 15, 2004

### chroot

Staff Emeritus
The neutral pi meson is a resonance -- it's either anti-up and up or anti-down and down, and you can't tell the two apart. The total quantum-mechanical state is a combination of both of those possibilitities. That's where the $\sqrt{2}$ comes in.

The negative pion is the "opposite" of the positive pion -- you can figure it out.

- Warren

Last edited: Apr 15, 2004
3. Apr 15, 2004

thank you!