Unraveling the Mystery of Neutrino Oscillations: What is the Coherence Length?

[frazzle]

I was wondering if anybody would be able to explain to me what this means? I can't seem to find out!

 

[pervect]

I'd assume it's the same idea as the optical coherence length for photons, but applied to neutrinos.

To quote the most relevant part of the wikipedia entry (there is a lot of fluff)

The coherence length is the optical path length difference of a self interfering laserbeam which corresponds to a 50% fringe visibility, where the fringe visibility is defined as V = (Imax - Imin)/(Imax + Imin) and I is the fringe intensity.

Note that optical coherence is used in stellar interferometery as well as lasers - the key idea is that photons will have visible interference fringes as long as the difference in path lengths is not too great. The coherence length is a measure of the maximum path length difference at which fringes will still occur.

I would assume that the concept applies in the same manner to neutrinos. Unfortunately, while neutrinos should theoretically interfere with themselves as do photons, it would be a lot harder to verify this via experiment as they interact so weakly.

 

[jankry]

Hi Frazzle,
have a look here

http://cdsweb.cern.ch/record/677618/files/p115.pdf

summarizing, the coherent length is the length along the neutrino propagation "during" which the mass eigenstates still overlaps, allowing the occurrence of the neutrino oscillation phenomenon. When the mass auto-functions are turned apart (and this happens because they have different masses, so different momenta which means a difference in speed) the original neutrino is split in separated mass eigenstates. Each one will have a separated propagation, skimming the possibility for the neutrino to oscillate.
In fact, the oscillation was the effect of different mass states which concurrently summed up to give the linear combination of a neutrino flavor.

Jankry

 

[Vanadium 50]

This post is four years old.

 

[jtbell]

And frazzle's last activity at all on PhysicsForums was on June 5, 2006, according to his profile.

 

[jankry]

yes, when I realized it it was late (submit button pressed already), nevertheless... neutrinos use to oscillate now as well as then, not caring of years... :)