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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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 ...
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How do we exactly use neutrinos to probe the core of the Sun (if they can only interact weakly)?

Neutrinos are interacting with ordinary matter weakly. They pass through matter mostly unimpeded. Thus, neutrinos typically pass through normal matter unimpeded and undetected. Neutrinos' low ...
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Do neutrino oscillations generate back-reaction in matter?

Typically all interactions generate some back-reaction. Neutrino oscillations are a subtle long-range interaction that induce weak-force interacting neutrinos to flavor-oscillate, and the properties ...
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Sterile neutrinos with a new Higgs field [closed]

If sterile neutrinos exist and the mass of neutrinos and sterile neutrinos is not gained by coupling to the Higgs field , is it possible there is a similar field like the Higgs which acts similarly ...
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1answer
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Help counting the number of real parameters in simple seesaw Lagrangian

The seesaw Lagrangian is $$-\mathcal{L}_{\rm mass}=\frac{Y^\ell_{ab}\langle H^0\rangle}{\sqrt{2}}\bar{\ell}_{aL}\ell_{bR}+\frac{Y^\nu_{ab}\langle H^0\rangle}{\sqrt{2}}\bar{\nu}_{aL}\nu_{bR}+\frac{1}{2}...
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Does a rotating black hole change a left-handed neutrino into a right-handed neutrino?

The Dirac equation in a gravitational field contains a torsion term $\overline{\psi}\gamma^\mu\omega^{nm}_\mu \sigma_{nm}\psi$. In the Weyl represnetation the spinor $\psi$ can be written as $\psi=(\...
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Does our failure to detect neutrinoless double beta decay spell trouble for the seesaw mechanism?

The seesaw mechanism is a theoretical model of neutrino masses that has the side benefit of (arguably) naturally explaining why neutrinos are so much lighter than the other massive Standard Model ...
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Why do people say that neutrinos are either Dirac or Majorana fermions?

The question of whether a given particle "is" a Dirac or Majorana fermion is more subtle than is sometimes presented. For example, if we just consider the "old" Standard Model with massless neutrinos, ...
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How do neutrino masses change the shape of the $\beta$ decay spectrum?

It is more-or-less established that neutrinos have masses. But as of now, $\nu$-masses have not been directly measured in the laboratory. But I heard a talk where the speaker said that efforts are ...
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Neutrino Oscillation Transition Probability With CP Violation

The transition probability for neutrino vacuum oscillation is $P_{\nu_{\alpha}\rightarrow\nu_{\beta}}=\delta_{\alpha\beta}-4\sum_{k>j}\text{Re}\left[U^{*}_{\alpha k}U_{\beta k}U_{\alpha j}U^{*}_{\...
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Show that $\nu^c _L = (\nu ^c)_R $

Considering Majorana neutrinos, how can I show that $\nu^c _L = (\nu ^c)_R $? I don't know how to answer this question. And what is the difference between $\nu ^c _R $ and $(\nu ^c)_R $? I know it ...
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Can CC interactions be used to detect oscillations $\bar{\nu_e} \to \bar{\nu_\mu}$?

Can CC interactions be used to detect oscillations $\bar{\nu_e} \to \bar{\nu_\mu}$? I believe this is not possible because CC interactions occur through the emission of a $W_{\pm}$ boson. This would ...
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What is the PMNS matrix for a 4 neutrino mixing scenario?

I am trying to compute the oscillation probability for: $$\nu_\bar{e} \to \nu_\bar{e} $$ I know I must use: $$P(\nu_\alpha \to \nu_\beta , t) = |\langle \nu_\beta |\nu, t\rangle|^2 = |\sum U_{\beta i}...
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Neutrino flavor models from irreducible representations of discrete groups [duplicate]

I am starting ph.D in neutrino physics-ph. I've read some papers on discrete symmetries and neutrino mass models. Neutrino flavor models are built using irreducible representations of discrete groups, ...
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3answers
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Does theory allow that one neutrino is massless and the other two not?

The question says it all. Is there the theoretical possibility that one of the neutrino mass eigenstates have zero mass, whereas the other two have not? Is there a theory that allows this option? I ...
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What is the evidence for 'billions of neutrinos pass through your body every second'?

This statement is repeated so often that it has become somewhat of a cliche: 'billions of neutrinos pass through your body every second'. For example see 1, 2, 3, 4, 5, 6. What is the evidence for it,...
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1answer
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How many $pep$-related electron-neutrinos $\nu_e$ does the Sun produce?

In the sun neutrinos can be produced by the rare proton-electron-proton (pep) reaction: $$ {}^1_1 H + e + {}^1_1 H \to {}^2_1 H + \nu_e $$ How many pep-related electron neutrinos does the Sun ...
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Interaction of neutrinos with matter

I am an undergraduate student working on a project on neutrino oscillations. I am currently trying to code the probability of neutrino oscillations in matter (MSW effect). I am using the following ...
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What percentage of the half-life for beta decay is accounted for by solar neutrinos?

Since detecting neutrinos / anti-neutrinos is difficult, when observing beta decay, it's hard to distinguish whether what happened was a capture of a neutrino (possibly a solar neutrino) or the ...
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2answers
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Do neutrinos really have a massless state? [duplicate]

I have read these questions: Do neutrinos change speed in neutrino oscillations? Neutrinos always travel at same speed? Neutrinos always travel at same speed? Where are all the slow neutrinos? ...
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Do neutrinos not interact with any kind of photons?

If billions of neutrinos reach us from the Sun why there is no any reflection of photons emitted from Earth to be reflected from them? Is this they are not interacting at all?
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If neutrinos were their own antiparticles, would be observe a photon background from $\nu$-$\nu$ annihilations?

If neutrinos were their own antiparticles, would we observe a photon background from neutrino-neutrino annihilations? As neutrinos are so abundant, why don't we observe such a background? Is the ...
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1answer
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Is relativity in action while we keep measuring some observable of a, let's say, neutrino?

Imagine a particle moving with non-zero velocity with respect to us. If I keep measuring an observable of the particle, such as position, then does the particle evolve relativistically? For example, ...
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Does the Fermi-Dirac distribution for massless fermions have any special interest?

Historically, the blackbody radiation (basically a system of photons in thermal equilibrium) played a pivotal role in the discovery of quantum theory. Initially, people used to think of neutrinos to ...
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1answer
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Super Kamiokande experiment with atmospheric neutrinos

Why did the super Kamiokande experiment see half the rate of atmospheric muon neutrinos from below than from above, but the same rates from electron neutrinos? It seems like it has to do with ...
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How to describe the interaction between a neutrino and a nucleus?

I know the basics of particle physics and QFT. How do you write it down the interaction between a a neutrino and an atomic nucleus (or many of them)? what equation or Lagrangian or anything else do ...
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Angular distribution of neutrinos in $e^-u\rightarrow\nu_ed$ scattering

What does the angular distribution of the neutrinos look like in the scattering $e^-u\rightarrow\nu_ed$? The tree-level Feynman diagram looks like this and since all of the fermions couple to a $W$ ...
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What is the antiparticle corresponding to the left neutrino $\nu_L$?

What is the antiparticle corresponding to $\nu_L$ ? -According to this thread : What distinguishes the behaviour of particle from its antiparticle: C violation or CP violation? "The operation that ...
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Would Majorana antinetrinos have opposite weak isospin?

There was a question about the difference between a neutrino and antineutrino, and answers suggested that weak isospin is different, as well as handedness. This would make sense if you expect pair ...
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What is dark parity?

What is the physical significance of the odd dark parity and even dark parity? Does it mean if a particle has odd dark parity then it is not a dark matter candidate?
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Is there a neutral current interaction between an antineutrino and an anti-strange quark?

I'm doing some revision for an exam and was wondering what the Feynman diagram for a charged current interaction between an antistrange quark - residing in a proton - and an incoming antineutrino ...
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A search for IceCube events in the direction of ANITA neutrino candidates

In regards to the recent discover by ANITA of space-bound high energy Neutrinos, could this possibly be explained by atmospheric Beta Decay reactions producing these Neutrinos in between the IceCube ...
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1answer
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Book suggestion about Neutrino effect on Cosmic Structure

I am trying to find some nice explanatory books about neutrino effects on the cosmic structure. I did not take GR so I prefer sources that contain not much GR. I prefer lecture note series or books ...
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Are the muon/tau neutrinos produced in the Sun? If not, then where?

I was reading about Solar Neutrinos, and apparently they are all Electron Neutrinos. However, there are two other types of neutrinos, the Muon and Tau Neutrinos. Does the Sun produce them? If not, ...
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Is there a glitch of wrong complex conjugate in the “$|\nu_\alpha\rangle=PMNS \times |\nu_i\rangle$” formula from PDG neutrino review? [duplicate]

How could the $|\nu_\alpha\rangle=PMNS \times |\nu_i\rangle$ formula from PDG neutrino review be incompatible (complex conjugate) with the one of wikipedia ? is PDG formula wrong ? Remark : they use ...
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With a given fixed flavor neutrino produced, after a long flight, will the measured flavor always be the same at the detector?

In theories explaining neutrino oscillations (with 3 neutrinos to make it simple), it is explained that a neutrino flavor eigenstate that is produced with an electroweak process is actually a ...
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Neutrino oscillation probability phase difference

So I found the graph above, as well as several others showing similar phenomena, in the wikipedia article for neutrino oscillations, and it quite clearly shows a phase difference between the ...
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1answer
61 views

Why neutrino mass hierarchy scenario do not include the case $m_2<m_1<m_3$ and the case $m_3<m_2<m_1$?

The neutrino mass hierarchies are made of two hypotheses/scenarios: the normal hierarchy: $m1<m2<m3$ the inverted hierarchy: $m3<m1<m2$ Why neutrino mass hierarchy scenario do not ...
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What is the interpretation of a statistical CL contour *in the case* where the central observed measurement does not belong to the interior?

What is the interpretation of a statistical Confidence Level contour in the case where the central observed measurement does not belong to the interior of the contour ? (you may see below that this ...
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How much larger would the IceCube Neutrino Observatory be to detect emissions from betelgeuse

How much larger would the IceCube Neutrino Observatory be to detect emissions from betelgeuse. I read that it is currently too far for us to detect whether a supernova is imminent. Would a larger ...
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What is the advantage of long baseline neutrino accelerators, with respect to short baseline ones?

What is the advantage of long baseline neutrino accelerators, with respect to short baseline ones ? Let me clarify : with long baseline, there is important MSW effect from travelling earth. There is ...
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1answer
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Do neutrinos in long baseline accelerators flight in matter and short baseline ones flight in vacuum, or are there exceptions? [closed]

Do neutrinos in long baseline experiments with accelerators flight in matter (Earth) and short baseline ones flight in vacuum, or are there exceptions ? Why don't long baseline neutrino experiments ...
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1answer
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Calculating the maximum total neutrino mass by using cosmological bound

In an article its written, $$\Omega_{\nu} = \frac{\rho_{\nu}}{\rho_{crit}}=\frac{\sum m_{i,\nu}n_{i,\nu}}{\rho_{crit}} = \frac{\sum m_{\nu}}{93.14h^2eV}$$ Now I am trying to derive this for myself ...
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How to prove that $E=2 \text{ GeV}$ drives to maximum of neutrino oscillation for $L=811 \text{ km}$ of NOvA experiment?

How to prove that E=2 GeV drives to maximum of neutrino oscillation for L=811 km of NOvA experiment (as NOvA claims) ? The dependence for $\nu_\mu\rightarrow\nu_\mu$ is $\sin^2{\frac{\Delta m^2_{32}L}...
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1answer
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In neutrino oscillation experiment, what are the Feynman diagrams involved for the *detection of the neutrino* in the detector?

In neutrino oscillation experiment, for example NOvA [but it could be other if you prefer], what are the diagrams involved for the detection of the neutrino in the detector ? I have explored inside ...
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1answer
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What happens in terms of neutrino oscillation if the distance is extremely high (much more than Sun-Earth distance) ? Is oscillation lost?

What happens in terms of neutrino oscillation if the distance is extremely high (much more than Sun-Earth distance) : is oscillation lost ? Why ? Is there decoherence of oscillation ? What does this ...
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Why is the baseline of solar neutrinos is reported as “only” 10^10 meters while distance Sun-Earth is 1.5e11 meters?

Solar neutrinos correspond to neutrinos produced by the sun, and travelling until Earth. The distance Earth-Sun is 150 millions km, which is 1.5e8 times 1e3 = 1.5e11 meters. So why the "baseline" (=...
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How could the baseline of atmospheric neutrinos be as much as $10^7$ meters while exosphere (outer part of atmosphere) is at most 8e5 meters?

Atmospheric neutrinos correspond to neutrinos produced by the interaction of cosmic rays in the Earth atmosphere. The Earth atmosphere is at most $800$ km=$8 \cdot 10^5$ meters. So how could the "...
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In neutrino oscillation experiment, such as NOvA, what particle does the neutrino interact with in the detector?

In such kind of schematic of Feynman diagrams involved in neutrino scattering with matter at neutrino oscillation experiments : (page labelled 54 = page 100 of the pdf file : http://inspirehep.net/...
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Cherenkov light reverse cone direction

The Cherenkov cone is emitted along the charged particle direction as many textbooks say. Detectors like Super-Kamiokande can detect those cerenkov rings and tag the particle as a muon-like ...

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