Questions tagged [neutrinos]

Neutrinos are light, uncharged leptons. The neutrino tag should be applied to question relating to neutrino properties or interactions involving neutrinos.

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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 ...
blacktopshaman's user avatar
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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 ...
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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 +...
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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 ...
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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 ...
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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 ...
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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 ...
The Burger King's user avatar
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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 ...
Sagar K. Biswal's user avatar
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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 ...
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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... ...
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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 ...
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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 ...
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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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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 ...
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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} +...
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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 ...
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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 ...
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Difference between $Q$ value and Total energy in a beta minus decay

I was going through the kinematics of beta minus decay. I understood that the $Q$ value in the beta minus decay is the sum of the KE of electron and anti-neutrino $$Q= E_e + E_\nu.$$ Here the $E_e$ ...
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Distinction between majorana neutrinos and sterile neutrinos

I am a bit confused about Majorana neutrinos. A generic Dirac spinor can be written in terms of his left and right-chiral components as $$ \psi = \begin{pmatrix} \psi_L \\ \psi_R \end{pmatrix} $$ A ...
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Do cosmological neutrino-antineutrino pairs annihilate at all?

Do low energy cosmological/relic neutrino-antineutrino pairs annihilate to produce photons at all? Their energy is presently too low to produce electron-positron pairs but there should be an indirect, ...
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Meaning of short, medium and long baselines

I was reading about the experiments on Neutrinos and came accross terms like "Short", "long" and "medium" baseline experiments. Can anyone please tell me how do we define ...
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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 ...
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How is the chirality for the weak interaction conserved for non-relativistic neutrinos?

In this article, one can read that the neutrinos in the cosmic neutrino background have a speed of about 1/50 of the speed of light, which is clearly non-relativistic. From the viewpoint of, say, ...
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How long does it take before neutrino velocities in the neutrino background radiation are substantially less than the speed of light?

The energy of photons is reduced by the expansion of space. Since the photons have been decoupled from matter their wavelengths have decreased from the visible range to the radio range. The same ...
Il Guercio's user avatar
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Neutrino Mass from Tritium

I just read: Researchers close in on the elusive neutrino (phys.org) However, I think I'm missing something. The basic argument appears to be: (decay process) Tritium -> Helium-3 + β− (electron) +...
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The chirality of the standard model fermions

I read 'The Standard Model Effective Field Theory at Work' by Isidor, Wilsch, and Wyler. In a footnote, they say that, in principle, right-handed neutrinos could be included in the Standard Model by ...
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Helicity of cosmic neutrinos

If neutrino has mass, then it can change it's helicity. But all registered neutrinos have negative helicity while all anti-neutrinos have positive. Does it stands for all registered neutrinos ...
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Feynman diagram: Two-way arrow in the fermion propagator line?

I have encountered some diagrams (like the example below) where two lines coming out of a single vertex (in this context, right-handed neutrino $N^c$) have opposite direction. In a usual diagram, a ...
lost-neutrino's user avatar
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Cloud Chamber Help Needed! [closed]

I was inspired by this video to attempt to create a cloud chamber without dry ice (it's very challenging to get where I live) and I have had limited success so far. This is what the design looks like: ...
Carl Davis's user avatar
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Neutrinos from a Type 1a Supernova

How much energy does a Type Ia Supernova produce in the form of neutrinos? I know that a Type II Supernova produces around $10^{45}$ joules worth of neutrinos, but not the amount produced by a Type 1a ...
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Will the universe be full of neutrinos?

If neutrinos are so easy to produce, but it rarely get absorbed or detected, doesn't that mean the universe will be full of neutrinos? Will its density ever reach a balance where its absorption events ...
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Is Dirac neutrino ruled out by current experimental observation?

I have read the neutrino mass problem. The unnatural smallness of neutrino mass implies the existence of new physics so the seesaw mechanism is introduced to solve this theoretical problem. I ...
StupiXPerson's user avatar
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What happened in March 1991 when the IMB neutrino detector sprung a leak?

When I was in grad school, I recall hearing a story something like this: "Once upon a time, there was a neutrino detector (Cherenkov water detector--just a large bag [in my memory of the story it ...
Will Levine's user avatar
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$\beta^{+}$ and $\beta^{-}$ decay processes

We know that electron cannot exist inside the nucleus for various reasons like its energy, angular momentum violation and etc. But these $\beta^{+}$ and $\beta^{-}$ processes occurs inside the nuclei ...
Anshul Sharma's user avatar
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Why can't Dark matter be made up mostly of Neutrinos? [duplicate]

It's said that Neutirnos can only make up a tiny fraciton of dark matter. So why can't Dark matter be mostly made up of Neutrinos? Why can't there just be a huge number of them? I suspect myself that ...
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Scatter angles at IceCube

Is it possible to have a scatter angle(in lab frame) to be greater than 90 degrees at IceCube, with this I mean the relative angle between the incoming (muon) neutrino and the outgoing (muon)lepton. $$...
Peter17's user avatar
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1 answer
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How do the different Neutrino masses come about?

The determination of the Neutrino mass can be roughly divided in three strategies: The neutrino mass from cosmological observations: $$m_\nu = \sum_{i} m_i $$ The neutrino mass from the neutrinoless ...
Marc's user avatar
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Has Anti-beta decay been observed?

I am looking for references or resources regarding the transition of an anti-neutron through weak decay, into an anti-proton, positron, and electron-neutrino. Have such studies been conducted or ...
2 votes
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Does neutrino oscillation imply that the lightest neutrino has mass? [duplicate]

If my understanding is correct, neutrino oscillation only implies that the neutrino families have different masses. People usually infer from this that all the masses are non-zero, but we can only ...
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Neutrino oscillations imply neutrino mass — Does the usual argument really hold?

An argument that people put forth is that because neutrinos can undergo changes in lepton flavor midflight, they must "experience time." Since massless particles must travel at the speed of ...
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Maximum energy of neutrino from decay of $W$ boson

Figure 2 of this paper suggests that neutrinos from the decay of on shell W bosons can have an energy as high as the W boson mass. However, in the $W^{-} \rightarrow e^{-} + \bar{\nu}_{e}$ process, ...
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(Basic) confusion about value of scalar-fermion vertex $\phi\psi_i\psi_j$ for Majorana fermions

If I have a toy model with $N$ Majorana fermions $\lbrace\psi_i\rbrace_{i=1,\ldots,N}$ and a scalar field $\phi$ where the interaction among the fields is $$ \mathcal L_\text{int}= \sum_{i,j=1}^N a_{...
Boris Valderrama's user avatar
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Dirac neutrinos?

How can Dirac neutrinos exist if neutrinos have no charge? As far as I'm aware, the antiparticle of a particle is its charge conjugate while all of its other characteristics remain same. How then can ...
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What is the control group in neutrino detection?

Assuming we can't block neutrinos, and most of them pass through the earth, how do we know that the change in the neutrino detector is not just happened randomly? Is the detection of neutrinos more ...
daniel's user avatar
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Plotting the bipolar neutrino oscillations in supernova

everyone. I am trying to study the neutrino oscillation in a core collapse supernova. In certain situations neutrinos in supernova can undergo what is called a "bipolar" oscillation. ...
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What’s the most energetic particles that can theoretically reach the earth?

In recent years several ultra high energy cosmic ray events are observed on Earth. These particles carry energies way beyond even the most powerful particle accelerators we can realistically build. ...
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How can neutrinos be solely left-handed if they have mass?

Helicity: projection of spin onto motion. Since neutrinos are massive, I can always move to a reference frame where their motion is towards the opposite direction, meaning I should reverse their ...
TrentKent6's user avatar
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Why neutrino's mass states are assumed to share the same momentum?

In derivation of two-neutrino oscillation probability, it was assumed that the mass states have the same momentum. Why is that? Source: https://www.youtube.com/watch?v=nXzur-2hbkI&t=115s&...
HaneenSu's user avatar
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Beta decay experiments suggesting that neutrinos are massless

It's known that in the kinetic energy spectra of electrons from the negative beta decays that at the end of the spectra some electrons are found to have a maximum energy that is equal to the energy ...
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How does neutrino free streaming length affect the growth of structures in the universe?

I cannot quite wrap my head around the exact mechanism by which neutrinos affect cosmic structure growth. Their effect as dark matter is clear to me but I don't understand how their longer free ...
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