All Questions
12 questions
0
votes
2
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129
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Could neutrinos eventually decay? Or are they indefinitely stable?
I was having a discussion with someone here in stack exchange and they came up with the following arguments for the possibility that neutrinos (and other fundamental particles like electrons) may ...
- 2,878
0
votes
1
answer
64
views
Mass difference of $B^0$, $\overline{B^0}$-states
It is known that $B^0$, $\overline{B^0}$ or $K^0$, $\overline{K^0}$ particles have different masses and that they oscillate in 'an equivalent' way to neutrino oscillations.
Is it theoretically ...
- 498
0
votes
1
answer
506
views
How are neutrino energy eigenstates different to the momentum eigenstates?
Neutrino flavour eigenstates can be expressed (approximately) in terms of their mass eigenstates, leading to neutrino oscillations.
$|\nu_e\rangle = \cos \theta |\nu_1\rangle - \sin \theta |\nu_2\...
- 28
1
vote
1
answer
96
views
How do weak interactions maintain thermal equilibrium in the early universe?
When reading about why SM neutrinos are not a candidate for DM, it was stated:
"Neutrinos are involved in weak interactions that keep them in thermal equilibrium in the early Universe down to the ...
- 109
2
votes
2
answers
444
views
Neutrino flavor change in flight
I have read this article:
https://profmattstrassler.com/articles-and-posts/particle-physics-basics/neutrinos/neutrino-types-and-neutrino-oscillations/velocity-differences-of-neutrinos/
https://en....
- 29.3k
6
votes
3
answers
2k
views
Unitarity of PMNS matrix
Why should the neutrino mixing matrix (PMNS matrix) be unitary? Is the unitarity dictated by experiments or is it a theoretical demand?
- 27.2k
1
vote
2
answers
187
views
Comparison between two flavor neutrino oscillation and a system of up-spin and down-spin states of an electron?
In the system of up-spin and down-spin states of an electron, we can write a general state of electron at time $t$ as
$$\left|\psi(t)\right>=a\left|\uparrow\right>+b\left|\downarrow\right>,$$...
- 105
0
votes
1
answer
240
views
Observable Vs Projector in case of Neutrinos
For a spin $s$ system, we can define the observable $A=S_z$, such that $A(t) = S_z(t) = U^\dagger S_z U$, where $U$ is the unitary operator $e^{-iHt}$. We can always define a projector $\Pi_m = |s,m \...
- 592
4
votes
0
answers
1k
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Neutrino interaction probability [closed]
Just a quick question, if a single 1GeV neutrino (muon neutrino) were fired at a block of iron with a given density, $\rho$, and the neutrino-nucleon interaction cross section is $\sigma$, what would ...
- 1,644
3
votes
1
answer
131
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How do physicists find the speed of neutrinos?
I have heard that there is evidence for neutrinos traveling close to the speed of light, but how is that done? Since neutrinos barely react with anything, and the only evidence for them is indirect (...
user118682
4
votes
1
answer
331
views
How quickly do neutrinos change flavor?
DOE’s Fermilab has switched on its newly upgraded neutrino beam. This is in preparation for the NOvA experiment, which will study neutrinos using a 200-ton particle detector at Fermilab and a 14,000-...
- 648
0
votes
1
answer
230
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Neutrino mass and the Majorana equation
I can't seem find this on the Internet. What does the Majorana equation predict neutrino masses to be (if they were their own antiparticle), and how?
(I have little understanding of spinors, btw...)
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