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The interaction term disappears because when you integrate out the right handed neutrinos you insert in a linear combination of the other fields in their place. For example I expect that we would have something of the form, G _{ ij} \sigma \bar{\nu} _L ^i \nu _R ^j \rightarrow G _{ij} G _{jk}\sigma ^2 \bar{\nu} _L ^i \nu _L ^k ...

0

The real reason is in following. Let's assume Majorana field: $$\Psi_{M} = \Psi_{L} + \hat{C}\bar{\Psi}^{T}_{L}, \quad \hat{C} = i\gamma_{2}\gamma_{0}, \quad \Psi_{L} = \begin{pmatrix} \psi_{L} \\ 0 \end{pmatrix}.$$ By using this notation it's not hard to see that kinetic term is equal to $$\bar{\Psi}_{M}\gamma^{\mu}\partial_{\mu}\Psi_{M} = ... 0 The short asnwer to your question is that the overall factor \frac{1}{2} from the Lagrangian of a Majorana field (in the 4-component notation)$$\mathcal{L}=\frac{1}{2}(\bar{\psi}i\gamma^{\mu}\partial_{\mu}\psi -m\bar{\psi}\psi) compared to the general Dirac Lagrangian is usual for self-conjugate fields and it is introduced to ensure a consistent ...

1

OK, let's try a back of the envelope... http://www.slac.stanford.edu/econf/C0805263/Slides/Budge.pdf states that the total anti-neutrino count from a supernova is on the order of 1e58 and the neutrino energy is on the order of 40MeV. Let's imagine all of these neutrinos would go trough earth, which is the worst case scenario. The nuclear cross section of ...

6

Yes, but it should be stated that the cosmic neutrino background is expected to be very cold and very difficult to see. Also, note that when temperatures approach the electroweak unification scale, the electroweak force will treat electrons and neutrinos identically, and the universe will become opaque to neutrinos.

4

The experiment detected more than just solar neutrinos, it also detected those produced by interactions with muons from cosmic rays, radioactive decays in the rocks surrounding the mine, internal radioactive contaminants in their tetracholorethylene fluid, and atmospheric argon decay production, but like any good experiment they controlled and subtracted all ...

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