# Tag Info

1

CP-violation in standard model is due to CKM complex phase of the quarks sector. You can see the parametrization of CKM matrix, like Wolfenstein parametrization, and see that there is only a phase in CKM matrix, the work of Kobayashi-Maskawa is about to understand that you need three generation of quarks to have CP-violation. Now you can have a similar ...

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In the Standard Model, the lepton sector does not have CP violating couplings (at tree level). The quark sector however has CP-violating couplings (through the CKM matrix). The PMNS matrix (describing neutrino mixing), may have a complex phase (implying CP violation). Whether it has a nonzero phase or not remains to be tested experimentally. This is ...

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Notation $W^{-}, W^{+}$ may confuse in a sense that it may seem that here are two different particles which aren't connected by charge conjugation. But of course, $W^{+}$ is only $(W^{-})^{\dagger}$, so it is an antiparticle to $W^{-}$. So term $( W^{-} \cdot W^{+} )$ is simple $|W|^{2}$ (which is standard for the mass-term), and, of course, both of particle ...

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The electroweak Lagrangian contains terms which are not eigenstates of $P$, but (to good approximation) only terms which are eigenstates of $T$. Since $CPT$ is an exact symmetry, the electroweak Lagrangian must contain terms which are not eigenstates of $C$.

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Weak interactions include only the left neutrinos (and right antineutrinos). It means that all neutrino-interaction terms in the Lagrangian also consist only the left particles (and right antiparticles), because $\bar{\Psi}\gamma^{\mu}\Phi_{R, L} = \bar{\Psi}_{R, L}\gamma^{\mu}\Phi_{R, L}$. It means that the charged current terms \$L_{\int}^{CC} = g ...

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The link posted by akhmetelli suggests it's because of parity nonconservation: in the center-of-mass frame for the scattering, at high energy, only left-handed particles and right-handed antiparticles participate in the weak interaction. The two particles may always scatter through an angle of 0º; the technical term for that is "they missed." So the ...

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Looks like the answer is quite messy - I cannot reproduce it here - ...

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