We next turn to the evidence on the weak decay of these particles. The experimental information on masses and decay properties of all the particles is given in Table 12-1. We are concerned here only with the decays of hyperons and mesons. Two of the decays clearly are the result of electromagnetic couplings (in association with virtual states implied by strong coupling), the π° →γ + γ and the Σ° → Λ + γ. These are also the only ones 56allowed by conservation of charge and the principle that electromagnetic couplings cannot alter strangeness. Table 12-1

Products

Ratio, %

Lifetime, sec

n   →   p   +   e   +   ν ¯ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429492501/e6a0c676-1f8d-4684-97a0-6bf3353f7ce0/content/eq166.tif"/>

1040

Λ → p + π⁻

63 ± 3

2.6 × 10⁻¹⁰

n + π°

37 ± 3

Σ⁺ → p + π°

46 ± 6

0.8 × 10⁻¹⁰

n + π⁺

54 ± 6

Σ⁻ n + π⁻

100

l.6 × 10⁻¹⁰

Ξ⁻ → Λ + π⁻

?

≈ 10⁻⁹

π⁺ → μ⁺ + ν

100

2.56 × 10⁻⁸

e⁺ + ν

0.013

K⁺ → μ⁺ + ν

59 ± 2

1.22 × 10⁻⁸

π⁺ + π°

26 ± 2

π⁺ + π⁺ + π⁻

5.7 ± 0.3

π⁺ + π° + π°

1.7 ± 0.3

π° + e⁺ + ν

4.2 ± 0.4

π° + μ⁺ + ν

4.0 ± 0.8

K 1 ∘   →   π +   +   π − https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429492501/e6a0c676-1f8d-4684-97a0-6bf3353f7ce0/content/eq167.tif"/>

78 ± 6

1.0 × 10⁻¹⁰

π° + π°

22 ± 6