Survival probability solar neutrinos

[TheWire247]

I am trying to explain why why the survival probability for solar neutrinos is different for different neutrino solar lines, and what causes this difference.

 

[Orodruin]

What do you mean by "different for solar neutrino lines"? Different from what? Also, what is your exact question?

 

[TheWire247]

Sorry, I have corrected the question now. I need some help explaining it. I am referring to the solar neutrino energy spectrum

 

[Orodruin]

You need to provide a more specific question and inform us about your current level of understanding if we are going to have any chance of helping you at an appropriate level. There are several good reviews on this subject available online. Keywords to look out for (in addition to the obvious) are MSW effect and adiabatic flavour conversion.

 

[TheWire247]

My understanding of solar neutrino physics is pretty basic as I'm currently trying to get to grips with this field. I have a reasonable understanding of particle physics in general.

 

[Orodruin]

This still tells us nothing of what specific problem you are having. You need to show what you have been thinking so far and where you get into trouble. This is a standard derivation that will be available in any neutrino physics review.

 

[TheWire247]

From what I can tell the lower the energy the better the survival probability i.e. pp neutrinos have a better survival probability than 8B neutrinos. I'm not sure how this relates to the MSW effect. I am looking at this purely qualitatively.

 

[TheWire247]

Could there be some effect from neutrino-neutrino interactions in the sun's neutrinosphere?

 

[Orodruin]

At high energies, the solar interior is so dense that neutrinos produced there are produced almost exclusively in the second neutrino matter eigenstate. Propagation is adiabatic so the neutrinos exit the Sun and arrive at Earth in the second mass eigenstate, which only has a minor component of electron neutrino which gives a probability less than 0.5.

For low energy neutrinos, the solar interior is not dense enough to reach resonance energies and the transitions are essentially averaged vacuum oscillations which always has a survival probability greater than 0.5.

 

[Orodruin]

Could there be some effect from neutrino-neutrino interactions in the sun's neutrinosphere?

No. The Sun does not have a neutrino sphere and the neutrino density is waaaaay to low for it to have any kind of impact.

 

[ChrisVer]

For low energy neutrinos, the solar interior is not dense enough to reach resonance energies and the transitions are essentially averaged vacuum oscillations which always has a survival probability greater than 0.5.

Could you explain a little what you mean by that?

 

[Orodruin]

Could you explain a little what you mean by that?

Which part?

 

[ChrisVer]

that the "transitions are averaged vacuum oscillations"

 

[Orodruin]

There are several reasons the vacuum oscillations average out. One of them is that vacuum oscillations of plane waves would be so fast that no detector could resolve them. My favourite is that with reasonable assumptions on the wave packet sizes and velocities, the wave packets would separate before arriving on Earth, giving complete loss of the interference between the mass eigenstates and, thus, remove the oscillatin terms from the survival probability (and from the transition probability too, of course).