1. Jan 29, 2015

### Clear Mind

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)

2. Jan 29, 2015

### dukwon

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

3. Jan 29, 2015

### Orodruin

Staff Emeritus
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.

4. Jan 29, 2015

### Clear Mind

Thank you all!
I suppose that the cross section it's really small ...

5. Jan 29, 2015

### Orodruin

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

6. Jan 29, 2015

### Clear Mind

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 :(

7. Jan 29, 2015

### dukwon

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.

8. Jan 29, 2015

### ChrisVer

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

9. Jan 29, 2015

### dukwon

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

10. Jan 29, 2015

### Clear Mind

Right! i was considering only charge, baryon, lepton and fermion numbers but not the parity :s

11. Jan 29, 2015

### ChrisVer

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

12. Jan 29, 2015

### Staff: 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.