0
$\begingroup$

How can a neutrino turn a neutron into a proton? This is the equation, $$ \nu_e + n \to p + e^- \,.$$

If you draw the Feynnmann Diagram which I attempted here, "Diagram" there isn't an exchange that could transfer the positive charge from neutron to the proton? Since $\nu_e$ and Neutron are neutral, where does this reaction gain its charge? I don't get this.

Improve this question
$\endgroup$
1
  • 1
    $\begingroup$ At the vertex level this is $\nu_e + d \to u + e^-$, but in either case the total charge is conserved (that is, it's the same after the interaction as before). $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Jan 8, 2014 at 2:24

3 Answers 3

Reset to default
2
$\begingroup$

As it is a weak interaction, your particle can be a $W^+$ or $W^-$ (depending on which direction it goes in time).

Improve this answer
$\endgroup$
2
$\begingroup$

How can a neutrino turn a neutron into a proton?

For example, an electron neutrino in the vicinity of a neutron 'emits' a virtual $W^+$ thus becoming an electron (the $W^+$ has +1 electric charge and up/anti-down weak isospin charge) .

The virtual $W^+$ is 'absorbed' by a valence $d$ quark within the neutron thus becoming a $u$ quark and the neutron is now a proton.

enter image description here
(source: a-levelphysicstutor.com)

Improve this answer
$\endgroup$
1
$\begingroup$

The exchange particle is a W-boson, as it must be at a neutrino--charged-lepton vertex.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.