All Questions
947 questions
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If neutrinos have non-zero mass, and hence are not in a pure chiral state, couldn't the sterile neutrinos still interact with the Weak Force?
I was reading this article on neutrino physics, and there's one point in the Seesaw mechanism I didn't understand:
If neutrinos have mass, the mass eigenstates need to have an admixture of left-handed ...
- 241
0
votes
0
answers
57
views
Neutrino oscillation via some unknown interaction mechanism
My query is based on this post. Similar to the Feynman diagram proposed in the problem, why don't we consider a similar mechanism in beyond standard model to explain the neutrino oscillation? It would ...
- 378
-6
votes
2
answers
114
views
Are high-energy neutrinos subject of relativistic time dilation like muons are?
Synchrotron experiments and cosmic-rays hitting our atmosphere have proved many times that high-energy massive muons moving with speeds close to the speed of light are subject to relativistic length ...
- 4,376
1
vote
1
answer
68
views
Do neutrinos have a $4π$-symmetry the same as electrons have?
We know that all charged elementary ferrmion particles (i.e. spin-1/2 elementary particles) have a Dirac $4π$-symmetry meaning that they return the same phase after two $2π$ rotations (i.e. 720°) in ...
- 4,376
1
vote
0
answers
64
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Deriving the EFT from a Lagrangian with a Right-Handed Neutrino Field
I am working through the MIT EFT course, and I am having trouble with one of the problems. The task is to find the effective field theory (EFT) from the most general Lagrangian with a right-handed ...
- 332
0
votes
1
answer
91
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General mass term for Majorana fermions
I have a question regarding the most general mass terms for Majorana fermions.
In the literature it is often stated that the most general Majorana mass term is
$$
\mathcal{L}^M_{\rm mass} = -m_D\...
0
votes
0
answers
40
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Calculations Regarding Neutrino Self-Interaction
I have recently been looking at papers talking about neutrino self-interactions and have seen quite different results among papers. One considers the addition of ${\mathcal{L}} \supset \frac{\lambda_{\...
- 291
0
votes
0
answers
40
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Unable to reproduce graph of sterile neutrino production
As a computational project, I've been trying to reproduce figures 3 and 4 of this paper which show the production of sterile neutrinos in the presence of neutrino self interactions as a function of ...
- 291
2
votes
1
answer
118
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Two questions about the expansion of the universe and matter?
I have a couple of questions about the consequences that the expansion of the universe (being an accelerated expansion or a linear one) would have on matter and structures in the universe
1. Neutrinos:...
- 2,878
1
vote
0
answers
33
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Do the equations $T_{\nu}(t)=\frac{T_{\nu ,0}}{a(t)}$ and $T_{\gamma}(t)=\frac{T_{\gamma,0}}{a(t)}$ actually hold at all times?
I’ve always been under the impression that $T_{\nu}(t)=\frac{T_{\nu ,0}}{a(t)}$ and $T_{\gamma}(t)=\frac{T_{\gamma,0}}{a(t)}$ describe the neutrino and photon temperatures (respectively) throughout ...
- 291
3
votes
0
answers
62
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Are relic neutrinos gravitationally bound to large scale structures?
I have been interested in how neutrinos arrange themselves around gravitational potentials. However, I found contradictory claims and I would like to clarify this
After reading a bit into this paper (...
- 2,878
0
votes
0
answers
36
views
Can the LHC dataset provide insights into the early universe during neutrino decoupling?
The LHC has produced an enormous dataset. I'm curious to know if any analyses could be (or have been?) performed on this data to search for signatures related to neutrinos that decoupled from matter ...
- 258
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
2
votes
1
answer
107
views
Can the gallium anomaly be explained by the transformation of neutrinos to electrons?
A 2024 review of the gallium anomaly summarizes the issue as follows:
The measurements of the charged-current capture rate of neutrinos on 71-Ga from strong radioactive sources have yielded results ...
- 4,376
1
vote
1
answer
58
views
Angular momentum of matter halos?
How much momentum (or more specifically, angular momentum) could a matter halo (like a dark matter halo, a neutrino halo...) have? Is it possible that they may have high amounts of momentum?
For ...
- 2,878
3
votes
0
answers
223
views
How do you build a Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) detector?
*Milkjug-sized neutrino detector (the COHERENT neutrino detector):
https://news.uchicago.edu/story/worlds-smallest-neutrino-detector-observes-elusive-interactions-particles#:~:text=The%204%2Dinch%...
- 47
2
votes
0
answers
97
views
Gravitational halos made of neutrinos...?
I have been recently interested in how halos made of standard model particles could be formed and behave.
After asking some questions in this site, I was told about how neutrinos could form such halos....
- 2,878
3
votes
0
answers
96
views
Parity violation via symmetry breaking?
(Apologies in advance for a poorly formulated question.) In Physics, if something can be equally well found in state A or state B, but for whatever reason is in state A, we sometimes observe the ...
- 3,013
0
votes
1
answer
50
views
What are some highly unstable phenomena you can observe from lightyears away?
I'm currently drafting some scifi story where the protagonist is in a long timeloop and wants to figure out when the loop starts exactly based on observing some unstable phenomena, like atomic decay ...
- 181
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
0
votes
0
answers
43
views
Can we calculate a lower bound on neutrino masses using de-Brogile?
Can we calculate a lower mass for neutrinos?
My argument for a lower mass of $10^{-60}$ plank masses is as follows:
Assume a neutrino has non-zero mass. Then there is a frame of reference where the ...
- 287
1
vote
1
answer
89
views
Is it theoretically possible to aim a neutrino's trajectory without using a massive celestal body to aim it?
Recently, when reading about atomic rockets, I noticed an entry about spin-aligning neutrons to make them shoot out of the rocket's nozzle instead of randomly flying around to wreck the rocket.
...
1
vote
0
answers
65
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Hierarchy Problem vs ratio of masses in the Standard Model
In the Standard Model, the ratio between the top quark's mass to the neutrinos is at least about $2 \times 10^{11}$. It could rise by at least an order of magnitude in the coming years as the ...
- 747
0
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1
answer
73
views
Where is antineutrino in standard model Lagrangian?
I'm somewhat confused by the content I studied in Srednicki's work, where the neutrino is described as a Majorana field. In this framework, there shouldn't technically be antineutrinos, given the ...
- 631
0
votes
0
answers
29
views
Adiabtic aproximation and MSW effect
I have been reading about the MSW effect in neutrinos from supernovae. In some papers, it's assumed the "adiabatic case" which, according to the book "Neutrino Physics and Astrophysics&...
- 161
0
votes
0
answers
41
views
Can a particle have properties of both Dirac and Majorana particles?
Dirac fermions have antiparticles of opposite properties, and only a particle and an antiparticle can annihilate. Majorana fermions have no antiparticles because they can annihilate with themselves. ...
- 1,537
0
votes
1
answer
69
views
How does Diagonalizing Mass Terms Affect the Lagrangian?
One thing I don't get about mass diagonalization, is doesn't this also change the kinetic terms of your theory? You would get some off-diagonal kinetic terms. How do we deal with this?
What also ...
0
votes
2
answers
86
views
Questioning the Probability Expression for Neutrino Oscillation in Griffiths' "Introduction to Elementary Particles"
In Griffiths' book, Introduction to Elementary Particles (Griffiths, D. (2020). John Wiley & Sons, p. 390), the author defines the pure electron and muon neutrino states as:
$$|ν_{e}\rangle=-\sinθ|...
- 77
1
vote
1
answer
88
views
Given that there are neutrino oscillations, why do we still need three distinct neutrinos instead of just one? [duplicate]
The three (distinct) neutrino flavors had been discovered before neutrino oscillations were discovered. Until then, it seems to have been logical to think of them as three types of distinct particles ...
- 300
2
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1
answer
52
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Abelian vs non-abelian discrete symmetries in neutrino physics
I was reading about the parametrization of the PMNS matrix and stumbled upon an article of Serguey Petcov$^1$ about discrete flavour symmetries. It endeavors to see if there is a pattern induced by a ...
- 21
0
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0
answers
55
views
Can there be structures made from neutrinos that can have angular momentum?
Would it be possible to eventually have structures made from neutrinos somewhere in the universe, as it is indicated in this question (Are neutrino stars theoretically possible?), like halos of ...
- 2,878
0
votes
0
answers
20
views
How to measure the frequency at which neutrinos oscillate?
I just watched this video about detecting neutrinos for measuring neutrino oscillations. The experimental setup is basically as follows:
Generate muon neutrinos from high energy protons colliding ...
- 300
0
votes
0
answers
27
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CP Violation in Neutrinos Requied for Standard Model Baryogenesis
CP violation is required for baryogenesis in the standard model, but CP violation in the quark sector due to the CP violating phase in the CKM matrix is too small to account for it.
Following that, ...
- 109
0
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0
answers
39
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Within a generation, fermion species' mass seems like it could have an effect on how many of the fundamental forces it interacts with. Is this true?
So, fermions all interact with the gravitational force and the weak force. All fermion species.
Now, if you eliminate from that list, the particles that don't interact with electromagnetism, you ...
- 335
1
vote
0
answers
88
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Determining the single particle energies in a neutrino opacity calculation
I'm attempting to recreate some plots from this paper on neutrino opacity calculations for interacting matter at supra-nuclear densities. Namely, I'm trying to write a Python script to perform the ...
- 829
0
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1
answer
289
views
Understanding the Mixing Parameters in the PMNS Matrix
I'm trying to understand what the parameters in the PMNS matrix mean exactly. For the two neutrino case the single parameter is a fairly intuitive rotation between basis vectors, however the 3 angles +...
- 109
5
votes
2
answers
317
views
How can I understand neutrino mixing and the difference between flavour and mass eigenstates?
I understand that if neutrino flavour is just a superposition of mass eigenstates, the probabilities of detecting a particular flavour of neutrino will vary as they propagate since the time evolution ...
- 109
2
votes
1
answer
70
views
How fast do the neutrinos in the neutrino background radiation move through the universe?
The expansion of space drains energy from particles. That's why the CMBR contains less energy nowadays than in the early stages of the universe. What does this mean for the neutrinos present in the ...
- 460
1
vote
0
answers
71
views
Does the neutrino take on different masses/energy/mometum in beta decay?
I am currently learning about quantum mechanics in my 12th grade Physics course and we're currently covering nuclear energy levels.
I understand that alpha and gamma decay is discrete, as there is ...
- 11
0
votes
1
answer
42
views
Does the number of right chiral neutrinos always need to be the same as the number of anti left chiral neutrinos?
Neutrinos are only observed to have a left handed chirality and anti neutrinos are only observed as having a right chirality. In some beyond the standard model hypotheses neutrinos of right chirality ...
- 377
0
votes
3
answers
147
views
Neutrinos and Weak interaction
As a beginner in particle physics I have a small doubt. Do we get neutrinos as a product in any process involving weak interaction? Is emission of a neutrino signature of weak interaction? OR there is ...
- 377
3
votes
1
answer
107
views
Why would it be (or it be not) valid to take that neutrinos can follow the same path as null geodesics?
Basically my main question is the one in the heading of my post, because apparently "Gravitation" by Misner, Thorne and Wheeler takes it directly as true and valid (a common place for null ...
- 392
1
vote
0
answers
109
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Issues with neutrinoless double beta decay
After reading the paper, https://arxiv.org/abs/2312.15016, I realized how subtle is the usual statement that "neutrinoless double beta decay" implies that neutrinos are Majorana particles...
...
- 6,727
0
votes
1
answer
50
views
Neutrino propagates and becomes three mass neutrinos?
Neutrinos are produced as flavor eigenstates (coherent linear combination of mass eigenstates). If the distance traveled is large enough, the wave packages of the mass eigenstates will not overlap ...
- 49
0
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0
answers
48
views
Neutrinos becoming mass eigenstates in the early universe
I have two points where I would need clarification:
Neutrinos are present in the early universe as flavor eigenstates and as such they decouple from the thermal bath, I guess. However, today, at ...
- 49
7
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5
answers
2k
views
What happens when an anti-electron collides with a neutrino?
What happens when an anti-electron collides with a neutrino? If something does happen, is a photon released after the collision?
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0
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0
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48
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What is the mechanism for neutrino emissions from a black hole
In Black Holes and Time Warps, Kip Thorne describes a conference he and Stephen Hawking took in the 1970's where Hawking discussed black hole evaporation. He discussed radiating gravitational waves ...
- 2,754
1
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0
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76
views
What mass do neutrinos have in the early universe?
Since neutrinos interact constantly in the early universe, I assume that they are present as flavor eigenstates. However, they are Fermi-Dirac distributed,
\begin{equation}
f(E, T) = \frac{1}{e^{E/T} +...
- 49
1
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0
answers
55
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Solar neutrino deficit, 1/3 or 1/2?
The puzzle of the missing solar neutrinos is supposedly solved by neutrino oscillations. I understand the mechanism, but there is still one point which I find unclear.
For the energy range and ...
- 4,448
2
votes
1
answer
384
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Neutrino oscillations and neutrino mass measurement
At the KIT they have been measuring the mass of the electron neutrino with a huge spectrometer (i.e. they make an enormous effort) and already published limits on the highest possible electron ...
- 10.2k