Feynman diagrams - neutrino interactions

[billbray]

I have some well ordered feyman diagrams which have an incoming neutrino interacting at a vertex with a w boson and emitting an electron. since a neutrino can pass through some 18 light years of led without interacting, I'm wandering how a single neutrino interacts at this vertex?

 

[Vanadium 50]

The interaction rate is small, but not zero. That's why it's 18 light years and not 180 or 1800.

 

[ansgar]

The first thing you should think of is beta-decay where a neutrino is emitted, if a particle can be the final product, it can also be the initial probe (time symmetry).

here is the beta decay:
http://teachers.web.cern.ch/teachers/archiv/HST2002/feynman/exampl2.gif
(the wavy line is the W boson)

and this is the process if p was heavier than n:
http://hyperphysics.phy-astr.gsu.edu/Hbase/astro/imgast/ppfustep.gif

W couples to lepton and its neutrino, e.g. electron + (anti) electron neutrino (lepton # must be conserved)

Z couples to lepton and antilepton, e.g. eletron + positron / electron neutrino + anti electron neutrino

Neutrinos mainly interact with matter (as incoming particles) via inverse beta decay