Cabibbo mixing and the experiments that proved it

The “leaning structure” of weak interactions that now encompasses flavor mixing of three quark families and even CP violation started with Nicola Cabibboʼs proposal in the context of hyperon decays that the d and s quarks are “rotated” by an angle (Cabibbo angle). I will recall the origins of this radical idea and recount the key experiments that established its validity. In addition I will suggest possible new hyperon experiments.