From Newsgroup: sci.physics

ram@zedat.fu-berlin.de (Stefan Ram) wrote or quoted:

This quark flavor change is actually a beta decay, a consequence of
the /weak force/.

Ryder reports how /strangeness/ was introduced to explain the
absence of certain strong decays:

|When the +c and K-# particles decay, however,
|
|+c raA p + -CrU+; K-# raA + -CrU| + -CrU+, (1.4)
|
|the lifetimes are so long (ree 10rU+-|rU# s) that the decays must be
|due to the /weak interaction/, even though all the particles
|involved are hadrons. Why? Hadrons decaying into hadrons of
|a lower mass will surely do so by the strong interaction -
|unless violation of a conserved quantity is involved.
|
|We therefore introduce a quantum number S called
|'strangeness', assign S = 0 to -C and p, S = -1 to +c and S = +1
|to K-#, and invent the rule, /strong interactions conserve S,
|weak interactions change it/. Then it will be seen that, in
|reaction (1.3), the algebraic sum of S on both sides of the
|reaction is zero, so S is conserved, and it is a strong
|interaction - as found. In the decays (1.4), however, S
|changes from -1 to 0 or +1 to 0, so the decays /cannot/
|proceed by the strong interaction, and so are weak.
|
Quantum Field Theory (1996) - Lewis H. Ryder (1941/2018).


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