Question

Why the following reactions can not proceed as strong interactions 

(a) π⁻ + p → K ⁻ + Σ⁺ 

(b) d + d →⁴ He + π⁰?

Answer 1

(a) In this reaction initially the total strangeness quantum number 

S_i = S_π + S_p = 0 + 0 = 0, while for the final state 

S_f = S_K + S_Σ = −1 + (−1) = −2 

ΔS = −2. Therefore, the rule ΔS = 0 for strong interactions is violated. 

(b) The total isospin for the initial state I = 0 + 0 = 0, while for the final state I = 0 + 1 = 1.

ΔI = 1. Therefore, the rule ΔI = 0 for strong interactions is violated.