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The emergence of the Cabibbo angle in non-degenerate coupled systems of fermions

Quentin Duret·Bruno Machet
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Abstract

Investigating, in direct continuation of our previous paper hep-ph/0606303 the implications of the non-unitarity of mixing matrices for non-degenerate coupled systems that we demonstrated there, we examine more accurately the vicinity of Cabibbo-like mixing in quantum field theory. We show that it is possible to preserve one of its main features, namely that, in the space of mass eigenstates, the two requirements -- of universality for weak diagonal currents and -- of the absence of their non-diagonal counterparts, although not fulfilled separately any more, can however reduce to a single condition for a unique mixing angle theta\_c. This leads to tan (2 theta\_c)=+/- 1/2, or cos theta\_c \approx 0.9732, only 7/10000 away from experimental results. No mass ratio appears in the argumentation.

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Quentin Duret, Bruno Machet. 2006-10-12. The emergence of the Cabibbo angle in non-degenerate coupled systems of fermions. https://doi.org/10.1016/j.physletb.2006.10.011

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