All Questions
947 questions
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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
2
votes
1
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152
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Difference between right-handed and sterile neutrinos
Several SM extensions propose the addition of heavy, right-handed neutrinos to explain the smallness of neutrino masses. There are also theories adding a fourth, sterile neutrino in the context of ...
- 150
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2
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123
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If neutrinos are majorana fermions, will it be possible for a beta minus decay to emit a neutrino instead of an antineutrino?
If neutrinos are majorana fermions, neutrinos and antineutrinos should be equivalent. As a result, reactions like $n\rightarrow p+e^{-}+\nu$, $\nu+p\rightarrow n+e^{+}$ should be kinematically ...
- 1,537
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0
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172
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If neutrinos are majorana fermions, does that mean any massive, weakly interacting majorana fermions will decay into neutrinos easily?
In particle physics, Dirac fermions are protected by conserved quantum numbers (electric charges, color charges, etc.). As a result, Dirac fermions can only annihilate with their antiparticles, and ...
- 1,537
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381
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In a hypothetical neutrinoless beta decay, how the energy spectrum will look like?
If we consider a hypothetical situation in which $\beta^-$ deacay is happening without emitting any anti-neutrino, to be precise, a neutrinoless beta decay is happening. So, in this case, how the ...
- 452
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222
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How can we tell whether a double beta decay is neutrinoless or not?
If a double beta decay is neutrinoless, there will be no neutrino carrying the energy away and the electrons should carry the exact amount of energy of the decay. The problem is that because neutrinos ...
- 1,537
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80
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Neutrino Oscillation and FCNC
We know that in the Standard Model (SM) neutrinos are massless. But the discovery of neutrino oscillation suggests that neutrinos must have masses because only then there will be a mass basis for ...
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43
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What will happen if neutrinos are not massless particles? [duplicate]
In beta decay, explain qualitatively What will happen if neutrinos are not massless particles?
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36
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Finite distance propagation for charged particles
Usually, when it comes to studying QFT at a finite distance, the underlying problem is neutrino oscillations. Could it be relevant in some sense to study finite-distance propagation of charged ...
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2
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105
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Do neutrinos absorb light?
I have been reading about neutrinos lately. One thing that I found amazing about these, is that their detection is not so easy.
My question here is, do neutrinos absorb light?
user310315
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208
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What form of energy can a neutrino have in a beta decay process?
While solving numericals from the Concept of Physics by HC Verma , I noticed that he never mentioned the term kinetic energy of a neutrino. There were some questions asking about the maximum kinetic ...
- 8,476
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Physically understanding Dilation Symmetry of Eigenvalue-Eigenvector Identity
In the recent paper by Tao concerning the famous eigenvalue-eigenvector identity, I need some insight regarding the "Dilation Symmetry" from a physical perspective.
It is mentioned that if ...
- 125
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230
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Ultrarelativistic limit for neutrinos: Why is this approximation working?
In this section of the Wikipedia article on neutrino oscillations, a neutrino mass eigenstate $\left|\nu_i\right>$ is written as
$$\left|\nu_i(t)\right> = e^{-i(E_it-\vec p_i\cdot\vec{x})} \left|...
- 147
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1
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114
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Vacuum Cherenkov Radiation
Hi I was reading this paper (Pair Creation Constrains Superluminal Neutrino Propagation) for an assignment and I came across the following question:
in the article, it is said that if we assume that ...
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36
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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 ...
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584
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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
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648
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Flavor-changing neutral currents (FCNC) and leptons oscillations
I have some confusion regarding flavor-changing neutral currents (FCNC) processes and relative meson-antimeson oscillations. If the question has already been asked, I'm sorry, I didn't find what I was ...
- 1,094
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Rate of neutrino generation in Earth's core?
I know that there are radioactive elements present in the Earth's core, but has anyone determined how much? That is, do we have an estimate of the number of neutrinos per second generated within the ...
- 15.9k
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Are neutrinos' velocities related to their energies? As they are with other particles?
I have read extensively about neutrino energies, including in the popular press, and yet velocities of the neutrinos themselves (not the detectors they 'run into' or the leptons they 'create' after ...
- 4,709
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574
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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
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144
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Can there be Neutrino and antineutrino oscillations?
I don't know have rigor knowledge in neutrino oscillations. I just know that there is not a definite mass state for a definite flavor Just like with spin where you might have eigenstate $|+\rangle_z$ ...
- 12.1k
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2
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425
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Can 1-loop corrections generate a neutrino mass?
I'm looking at the Electroweak theory with massless neutrinos. The neutrino has an interaction with the $W$-boson and electron which gives 1-loop corrections to the propagator via the self-energy. I'm ...
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124
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Since neutrinos have mass, is there a neutrino aether that could be detected by a Michelson-Morley experiment?
If there are trillions of neutrinos per second passing through my body each second, would this density of particles qualify as a neutrino aether? If so, it seems in principle that an interference-...
- 368
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Principle of conservation of momentum
when a nucleus at rest emits a beta particle, it is found that velocities of the recoiling nucleus and the beta particle are not along the same straight line. How can this be possible in view of ...
user310315
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3
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Mass of All the Neutrinos
I have read that the Sun produces $2 \times 10^{38}$ Neutrinos per second weighing in at approximately 8 MeV.
I have 2 questions.
Is there any way to calculate how many neutrinos have been produced ...
- 2,754
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931
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Can photons turn into neutrinos, similar to 'pair production' of electrons and positrons?
Since neutrinos ate much lighter, and are their own antiparticles (Majorana), it should be much 'easier' than turning a photon into an electron-positron pair, correct?
- 4,709
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37
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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), ...
- 914
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Could Hawking radiation have a lot of neutrinos and dark matter?
Up till now I have thought that Hawking radiation would be mostly photons, since the temperatures are typically small. However, a comment on another question (thanks to John Doty) suggested that we ...
- 61.8k
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119
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$\mathcal{L}_{I}^{C C} $ global $U(1)$ invariance
It is well known that the SM lagrangian has the $U(1)$ symmetry. Considering for the moment the global symmetry $U(1)$, I am having some trouble seeing it in the following terms:
$$\mathcal{L}_{I}^{C ...
- 49
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80
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How to distinguish between $\pi$ neutrinos and $K$ neutrinos?
Consider the neutrinos produced by two decay channels:
$$
\pi^+ \rightarrow \mu^+ +\nu_\mu\,, \qquad\qquad K^+ \rightarrow \mu^+ +\nu_\mu\,.
$$
with $\pi$ decay being 10 times more likely than $K$ ...
- 1,047
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282
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If neutrinos were Majorana fermions, then what would be the lepton number of the neutrino?
Majorana particles are their own antiparticles and the lepton number of antimatter is -1 whereas for matter is +1, so if neutrinos were Majorana fermions, then what would be the lepton number of the ...
- 91
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Annihilation Scattering Cross-Section $N_{n}+N_{n} \rightarrow \nu_{i} + \nu_{j}$ [closed]
I'm calculating the annihilation scattering cross section for fermionic dark matter candidate. I got the following result for the squared amplitude,
$|\mathcal{M}|^2= \frac{h_{ji}f^{*}_{ij}}{(m^{2}_{{...
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34
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Can we build Fresnel lens for neutrinos?
Suppose we know neutrino mass and speed. This makes us know it's de Broglie wavelength in vacuum. Now suppose it is travelling through matter filled by some "atoms" with concentration $n$ ...
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371
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Can we affect nuclear warheads with neutrinos?
I heard, that we can either disarm or detonate nuclear warhead if we could target neutrino beam onto it. Is it true? Which reaction it would be? Conversion of neutrons to protons? Or conversion of ...
- 1,742
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32
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Energy density of a neutrino species
My question refers to the derivation of the energy density $p_{\nu,i}$ of a neutrino species given in the footnote on page 16 of Lecture Notes on Cosmology by Komatsu. I have reproduced this below:
$$...
- 201
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Are massless antineutrinos in the Standard Model right-handed or right-chiral?
For massless fermions, their chirality (determining under which representation of the Lorentz group they transform) and their helicity (projection of spin onto three-momentum) eigenvalues are the same....
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Why was the neutrino thought to be massless?
Wolfgang Pauli once said (regarding the neutrino):
I have done a terrible thing. I have postulated a particle that cannot be detected.
Why did he figure it couldn't be detected? Was this because he ...
- 405
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3
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304
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Why doesn't the interaction $\gamma~+~\gamma~ \rightarrow~ \nu ~+~ \bar{\nu}$ happen?
If we have a neutrino $\nu_e$ and an antineutrino $\bar{\nu_e}$, one would expect that a possible interaction would be that they would annihilate each other, producing possibly two photons. I do not ...
- 183
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603
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Conservation of lepton number in neutrino oscillation
I was wondering how neutrino oscillations are possible and lepton number is conserved, as for example in the decay of an anti-muon: $$\mu^+ = e^+ \nu_e \bar{\nu_{\mu}}$$ all lepton numbers are ...
- 351
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Has neutrinoless double-beta decay been observed?
After searching on this question in the archives here, it would appear that as of 2018, neutrinoless double beta decay had still not been observed. Has the situation changed since then? Can anybody ...
- 97.8k
3
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601
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What happens when a neutrino and antineutrino meet?
My minimal knowledge of matter/animatter interaction is that only light is released and they obliviate each other.
is this the same for neutrinos?
- 753
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origins of the beta-decay energy spectrum [duplicate]
I understand that when beta decay occurs in the nucleus, the reason that the emergent electrons possess a distribution of energies is that varying amounts of the total energy release in the reaction ...
- 97.8k
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494
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What causes neutrino thermal radiation?
Often in astrophysics, I see neutrino particles being considered as photons, in the sense that hot material emits neutrino thermal radiation.
There are a lot of similarities of neutrino and photon ...
- 111
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106
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Dirac equation for neutrinos
Neutrinos are described by spinors. But they don't have a defined mass (they are in a superposition). How can I write the Dirac (Majorana) equation for neutrinos?
Maybe
$$i \gamma^{\mu} \partial_{\mu} ...
- 225
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281
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Why did particle physicists believe the neutrino was massless, according to their Standard Model?
The Higgs field that gives (some) particles mass was theorized to solve problem(s) with the weak force; the neutrino only interacts with the weak force, so....
Also, it is a fermion, these otherwise ...
- 4,709
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Neutrino temperature
I was wondering if anybody knows the relation between the photon temperature $T$ and neutrino temperature $T_{\nu}$? And why this can be written as
$$T_{\nu}=\left(\frac{4}{11}\right)^{1 / 3} T \...
- 1
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0
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79
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Number and masses of right-handed neutrinos in the seesaw mechanism
In the Wikipedia article about the seesaw mechanism, it is argued that the seesaw mechanism "extends the Standard Model by assuming two or more additional right-handed neutrino fields", with ...
- 95
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1
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110
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Review of experiment $g-2$ of the muon
This week a new development was announced to measure the pressure of the muon magnetic moment and the variation of its result on the theoretical value. The question is: what is the meaning of this ...
- 1,526
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What happens in Neutrino-antineutrino annihilation? [duplicate]
They only interact with gravity and weak force, so how do they emit their energy? My theory is that they would somehow emit photons (?)
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2
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116
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Will a neutrino gas always stay at the same temperature?
Does the neutrino gas pervading the universe always have the same temperature? Does it still have the temperature as the neutrino gas that emerged from the big bang? Neutrinos don't interact, so how ...
