It's an easy question, let's consider this reaction:
##N+\nu_e \rightarrow e^{-}+P##
Is this reaction possible? If is not, what does violate?

(I think is possible because charge is conserved, baryon, lepton and fermion numbers are conserved. But i'm not totally sure)

dukwon
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Yes, this is charged-current neutrino scattering. It's one of the processes that neutrino detectors look for.

Clear Mind
Orodruin
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Yes.

However, note that for free neutrons, it is much more likely that the neutrons will decay naturally unless you have an outrageously high neutrino flux.

Clear Mind
Thank you all!
It's one of the processes that neutrino detectors look for.
I suppose that the cross section it's really small ...

Orodruin
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Thank you all!

I suppose that the cross section it's really small ...

This is why neutrino detectors are really big ... :)

From a few day i've started to study particle physics, so i'm still a little bit confused ... I was wondering:
##N+\nu_e \rightarrow e^{-}+P##
it's a weak interaction, so it should violate c-symmetry, thus:
##\bar{N}+\bar{\nu_e} \rightarrow e^{+}+\bar{P}##
shouldn't be possible ...
I'm a little puzzled :(

dukwon
Gold Member
It is possible if you make both a charge inversion and a parity operation, since the weak force couples to left-handed fermions and right-handed antifermions.

Usually when we talk about an antiparticle it's the CP-conjugate rather than the C-conjugate.

ChrisVer
Gold Member
yes it is impossible, because you turned a right-handed neutrino into a right-handed antineutrino .... which doesn't exist [in SM]

dukwon
Gold Member
yes it is impossible, because you turned a right-handed neutrino into a right-handed antineutrino .... which doesn't exist [in SM]

It's the other way round. Antineutrinos have to be right-handed in the Standard Model.

yes it is impossible, because you turned a right-handed neutrino into a right-handed antineutrino .... which doesn't exist [in SM]
Right! i was considering only charge, baryon, lepton and fermion numbers but not the parity :s

ChrisVer
Gold Member
It's the other way round. Antineutrinos have to be right-handed in the Standard Model.

OMG! indeed! Well I'm always forgetting the a-priori left and right... [except for when I write the doublets]...

mfb
Mentor
C and CP violation do not mean the process is completely impossible. It can have a different dependence on the relative angles (P violation), or occur a bit more or less frequent even with an additional P transformation (CP violation), but it is still possible.