The Quark Model — Question 2

Question 2

A strange meson charge fixes its light valence flavor

Let $Q_u/e=2/3$, $Q_d/e=Q_s/e=-1/3$, B=1/3 per quark and S=-1 only for s. Antiquarks reverse these additive numbers. A conventional meson has S=+1 and Q=+e.

1. Find its minimal light-flavor quark-antiquark composition and verify B.

2. Write the composition and Q,B,S of the antiparticle.

Question 2 - Solution

A strange meson charge fixes its light valence flavor

(a) Method and calculation

$$S=+1\Rightarrow\bar s,\quad Q_{\bar s}/e=+1/3.$$$$\boxed{u\bar s:\ Q/e=2/3+1/3=1,\ B=1/3-1/3=0}.$$

(b) Interpretation and further calculation

$$\boxed{\bar u s:\ Q/e=-2/3-1/3=-1}.$$$$\boxed{B=0,\quad S=-1}.$$

Physical check

These numbers determine the minimal light-flavor content, but do not determine the meson spin or radial excitation.