All Questions
Tagged with neutrinos quantum-mechanics
39 questions
18
votes
4
answers
6k
views
Neutrinos passing through black hole
I have read this:
https://en.wikipedia.org/wiki/Neutrino
The weak force has a very short range, gravity is extremely weak on the subatomic scale, and neutrinos, as leptons, do not participate in ...
- 29.3k
16
votes
1
answer
2k
views
Do electrons oscillate into muons just like electron-neutrinos into muon-neutrinos?
And if not, why? What is the difference to neutrinos oscillations?
- 1,892
9
votes
1
answer
501
views
Can I stand on a neutrino star?
Hypothetically, if neutrinos lost their energy in the expanding universe, slowed down, and collapsed in a vast and otherwise empty region under their own gravity, they might form a large object ...
- 12.9k
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
6
votes
1
answer
584
views
Photon Phase vs Time Evolution
If it is said that photons do not experience time or distance because they travel at light speed, then how can photons get out of phase with one another due to different path lengths? How can phase ...
- 11.2k
6
votes
1
answer
513
views
Derivation of neutrino oscillation phase factor
As we know, the neutrino $\nu_{\alpha}$ with flavor $\alpha=e,\mu,\tau$ is a linear combination of mass eigenstates:
$$
|\nu_{\alpha}\rangle=\sum_iU_{\alpha i}|\nu_i\rangle,\quad i=1,2,3
$$
where the ...
- 1,701
5
votes
1
answer
472
views
Bound states between neutrinos using Schrödinger's equation?
I would like to see if it's possible that neutrinos (with sufficiently slow velocities) could form bound states in a universe with matter (such as ours)
There is a cosmic neutrino background in the ...
- 2,878
5
votes
1
answer
335
views
Neutrino oscillations in their rest frame
One thing I've never really had a good feeling for is what neutrino oscillations would look like for a neutrino at rest.
Would the neutrino be sitting there with a mass that was uncertain until ...
- 1,931
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
4
votes
1
answer
555
views
Does a neutrino gas emit blackbody radiation?
My understanding of the microscopic "mechanism" of blackbody radiation* in a gas is as follows: interactions between fluctuating charge distributions in particles of a gas create a microscopic random ...
- 35.8k
4
votes
0
answers
1k
views
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
2
answers
1k
views
Does the uncertainty principle imply the existence of particles that exceed the speed of light?
The uncertainty principle allows for the creation of virtual particles (with non-zero mass) that exist for very short durations. This allows empty space to have particle pairs that pop into existence ...
3
votes
1
answer
539
views
Interaction between neutrino and an anti-neutrino?
What happens when a neutrino and an anti-neutrino interacts together? For example, what does a muon neutrino and anti-muon neutrino produce? it says in my book that it creates "muons and antimuons". ...
- 1,107
3
votes
1
answer
131
views
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
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
2
votes
1
answer
777
views
In neutrino absorption, what is it really that absorbs the neutrino?
I have read a lot of questions on this site about neutrino absorption, and all of them mention that usually when a neutron transforms into a proton or vica versa, that is really an up quark transforms ...
- 29.3k
1
vote
1
answer
179
views
Can neutrinos be entangled in their oscillations?
If two neutrinos are entangled somehow--say, for instance, by being created in the same reaction--would their flavor (Tau, Muon, Electron) be enangled, including in their oscillations between the ...
- 375
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
1
vote
1
answer
1k
views
Matrix representation of a triplet state
The $SU(2)$ triplet state is typically given in the fundamental representation as a column vector, e.g.
\begin{equation}
\vec{\Delta} = \left( \begin{array}{c}
\delta^{++} \\
\delta^+ \\
\...
- 9,005
1
vote
1
answer
89
views
Flavor Oscillations, the case of leptons
In the neutrino sector neutral particle oscillation occurs which gives rise to neutrino oscillation. From my currrent understanding , the observation of the neutrino oscillation occurred because the ...
- 585
1
vote
2
answers
65
views
Coherent Elastic Neutrino-Nucleus Scattering Energy Transfer
What is the meaning of coherent elastic in "coherent elastic neutrino-nucleus scattering"? What I understand is when a high energy particle such as neutrino interact with the nucleus as a ...
- 11
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
1
vote
1
answer
173
views
Pauli exclusion, scattering, "neutrino stars"
I've been wondering about how exactly the Pauli exclusion principle works--how it acts like a sort of repulsive "force" which doesn't allow one fermion to "be in the same place" as another. I ...
- 314
1
vote
1
answer
560
views
Time evolution operator acting on a non-eigenket
I'm taking a course in QM at my university, and I'm trying to work out an assignment given to the class by our professor. The setup is as follows:
The problem is about a simplified description of ...
- 263
1
vote
0
answers
63
views
What are the implications of the discovery of sterile neutrinos?
In this Ars Technica article we read:
Now Fermilab is back with its latest update, using two additional years of MiniBooNE data. The excess is still there, and it has edged even closer to the ...
- 871
0
votes
3
answers
76
views
Could neutrino oscillations be due to exchange of gamma rays?
I was wondering since the relativistic mass-energy of a gamma ray photon is 1.24 MeV/c^2 and the mass of an electron neutrino is < 2.2 eV/c^2 whether the oscillations between the two could, in the ...
- 1,562
0
votes
2
answers
128
views
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
0
votes
1
answer
574
views
What is the 'effective number of neutrino species'? And how does that, rather than the total number of them, affect the universe?
As stated above...
How can the the physics of early cosmology (articles about which are where I usually come across mentions of such) be affected by an 'effective' number of neutrino types, rather ...
- 4,709
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
0
votes
1
answer
230
views
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...)
...
- 479
0
votes
0
answers
99
views
Can we determine the polarization of a neutrino?
I recently read that neutrinos have a polarization property---their polarization is opposite to antineutrinos.
Is it possible to determine the polarization of a neutrino? For example, we can determine ...
- 137
0
votes
0
answers
36
views
Neutrino Interaction
Massive neutrinos are eigenstates of vacuum Hamiltonian. So any flavour can be expressed as a superposition of these states, and typical considerations of a 2-state system follow. What happens if ...
- 199
0
votes
0
answers
37
views
How can neutral elementary particles have spin magnetic moment? [duplicate]
The spin magnetic moment of a particle is proportional to q/2m, where q and m are charge and mass of the particle respectively. So if an elementary particle is neutral (like neutrinos or photons), ...
- 903
0
votes
0
answers
30
views
What is neutrino pair exchange? Can neutrino pair exchange deduce stronger-than-electromagnetic attractive forces between electrons?
I read recently about neutrino pair exchange. What is neutrino pair exchange? Can this exchange induce forces stronger than electromagnetic forces between electrons which in turn form attractive ...
- 557
0
votes
0
answers
149
views
Gravitons passing through matter like neutrinos
I have read these :
https://en.wikipedia.org/wiki/Graviton
https://en.wikipedia.org/wiki/Neutrino
where it says:
The weak force has a very short range, gravity is extremely weak on the subatomic ...
- 29.3k
0
votes
0
answers
185
views
Classical model for neutrino oscillations
Does there exist any classical analogue or model for neutrino oscillations in two as well as three flavor scenarios? I just went through the Wikipedia page https://en.wikipedia.org/wiki/...
- 592
-3
votes
3
answers
172
views
How can we experimentally tell that neutrinos are EM neutral?
Neutrinos are elementary particles, to our current knowledge they do have rest mass, but they are the lightest particles (with rest mass).
What we observe in neutrino experiments?
I do understand ...
- 29.3k