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10 Particle Physics – II
10.36
Fig. 10.6 Y − I 3 plot for
baryon octet
10.37
Fig. 10.7 Y − I 3 plot for
baryon decuplet
10.38 (a) The reaction channels for the pion reactions π
−
+ p → π
−
+ p and
π
−
+ p → π
0
+n are charge symmetric to the reactions, π
+
+n → π
+
+n
and π
+
+n → π
0
+ p. We can therefore expect the reaction cross sections
with pions to be nearly identical. On the other hand, the reactions with
kaons are not charge symmetric because K
+ and K
− do not constitute an
iso spin doublet but are particle–antiparticle. Typical reactions with K
+
are K
+
+ n → K
+
+ n and K
+
+ n → K
0
+ p
However for K
− many more channels are open.
K
−
+ p → K
−
+ p
→ K
0
+ n
→ Σ
+
+ π
−
→ Σ
0
+ π
0
→ Σ
−
+ π
+
So, there is no reason for σ(K
−
+ p) to be equal to σ(K
+
+ n).
(b) Because of the CPT theorem, K
0 and K 0 which are particle and antiparticle, cannot be distinguished by their decay modes, but can be identified through their distinct strong interaction process. Thus