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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Why measuring the octant of the atmospheric oscillation parameter of neutrinos is important?

As some of you may know, the PMNS mixing angle $\theta_{23}$ has been measured to a value very close to 45°. In other words, the oscillation amplitude (2 flavour approx.) which is driven by $\sin^2(2\...
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Does the neutrino interact with the photon?

I know that the straight answer is no, but in my EFT course, where we're interested in nonrenormalizable operators of the Lagrangian, things aren't so straightforward. The non-minimal QED Lagrangian ...
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How was Potassium used to estimate the effect of backgrounds in the Homestake experiment?

I'm trying to understand some of the details of the Homestake experiment, which attempted to measure the rate of neutrino production by the sun. In particular, I'm interested in how Davis et. al. ...
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Neutrino Oscillation and Probability

I am a fresher in a university pursuing physics major. I have been very passionate about neutrinos. So, I started studying them. But I have realised that, it requires a lot of mathematical physics ...
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Has there been experimental confirmation of electron capture being a neutrino source?

Detecting nuetrinos is not easy of course but it seems that there are several interesting ways of playing with neutrinos using radioactive sources that can only decay by electron capture. For example, ...
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How could the neutrino be a Dirac particle

I'm reading up about neutrinos now and I understand the possibility of neutrinos being Majorana particles and further theories can be thought of from that (like the seesaw mechanism). I'm still very ...
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Can I hit a high energy neutrino beam onto a water container with no damage?

I read at Super Kamiokande water is surrounded by many photomultiplers to detect neutrino interactions. I was wondering if water was stored into some container and yes then can I shoot a neutrio beam ...
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Doubly-charged scalar decay and spinors

In the minimal type-II seesaw, in addition to the SM Higgs doublet $\phi (\phi^+,\phi^0)^\top$, one introduces a complex $SU(2)_L$ scalar triplet that can be written as $$\Delta_{L}=\left(\begin{array}...
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How can I calculate the probability of Neutrino hiting in a certain detector?

I was looking through the DUNE experiment. And it led me to think, If there's way to calculate or do probability where the neutrino might hit in a large chunk of matter in a given neutrino beam rate.
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How to create a DIY magnetic horn?

I recently watched a video about Neutrino Beam from Symmetry Magazine and I did some research about how to create a magnetic horn. I came-up with a paper from CERN that explained how to create one. ...
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Neutrinos and black holes

As a new user I could not comment on Do neutrinos of any flavor get trapped in black holes? My question is that the Ice Cube facility has mapped Neutrinos coming from black holes, as stated in ...
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Cryogenic Particle Detectors

Recently, I started reading about Neutrinos, their types, oscillations and their detection. Today many experiments are being conducted to detect and measure oscillations of sterile neutrinos and anti-...
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Knowledge of the neutrino density in the Universe

If detecting neutrinos is so difficult, how do we have an estimate of how many of them pass through a cubic centimeter per second?
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How to find parameters $\theta_{12}, \theta_{13} $ and $ \theta_{23} $ for the lepton mixing matrix?

I am currently studying neutrino physics and read that the PMNS matrix can be expressed through $9$ real parameters. I especially see parameters such as $\sin\theta_{12}$ popping up though, and I don'...
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Why should a neutrino being nearly massless mean that they travel near the speed of light? [duplicate]

It seems to me that photons travel only at the speed of light due to some intrinsic property of photons but once a particle has mass, its mass (irrespective of how small this mass is) should have ...
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Decay and Invariant mass [closed]

Consider the following decay : \begin{equation} K^+\longrightarrow \pi^0 + e^+ + l^0 \end{equation} where $l^0$ is a neutral lepton. What kind of particle is $l^0$? For $K^+$ , if it's at rest, ...
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Why do we need hot dark matter?

Data on galaxy rotation curves suggested that not all the mass in the galaxy is accounted for and we can't observe them directly but remind me again why we need hot dark matter in the first place? ...
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What equation does KATRIN use to measure neutrino masses?

Source KATRIN weighs neutrinos produced by the nuclear decay of tritium, a radioactive isotope of hydrogen. When a tritium nucleus transmutes into a helium one, it ejects an electron and a neutrino (...
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Is the mass of the electron neutrino the quantum of mass?

Is the mass of the lightest neutrino, the electron neutrino, the quantum of mass? That is, is all mass in the universe an integer multiple of the mass of the electron neutrino?
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Confusion in Notation

Recently I am doing a project on KATRIN experiment, which motive is to find the neutrino mass. So in a paper the result shows $(m_\nu)^2 =(-1.0)^{+0.9}_{-1.1}$ $eV^2 $. I do not get the meaning of ...
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Are there any slow neutrinos? [duplicate]

Since we now know that neutrinos have a rest-mass, we ought to be able to observe relatively slow-moving neutrinos. Have we seen any?
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Sterile neutrino decay into three active neutrinos

I have found several sources that provide the expression of the decay rate of sterile neutrinos into three active neutrinos. In https://arxiv.org/abs/0705.1729 (p.40),https://arxiv.org/abs/0901.3589 (...
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$Z$-boson decay into two neutrinos depends on the Dirac or Majorana nature of the neutrinos?

The decay rate of the $Z$-boson into two active neutrinos $Z \rightarrow \nu \overline{\nu}$ can be calculated straightforwardly and I obtained the same as in the literature. However, I was wondering, ...
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Which 1-loop Feynman diagrams are possible from this Lagrangian interaction term?

$$ L_{int} = g \bar{L} \cdot \tilde H N $$ Where $g$ is the Yukawa coupling constant, $L$ is a lepton doublet, $H$ is the Higgs and $N$ is a right-handed neutrino. I think that at tree level only $\...
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Right-handed neutrinos Lagrangian and drawing Feynman diagrams from it

The Lagrangian for the right handed neutrino field is: $$ L_{\nu} = y_{\alpha i} \bar{L_{\alpha}} H^{\dagger} N_{i} + m_{i} \bar{N^{c}_{i}N_{i}} $$ With $ L_{\alpha} $ being the left-handed lepton ...
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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 ...
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Handedness over the current terms in Feynman diagrams

This is a question about the Feynman diagrams: imagine I want to calculate the following process: $$\nu_{e, L} + e^-_R \rightarrow \nu_{e, L} + e^-_R$$ I can have a t-channel diagram with $e^-_R e^-...
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Fermi's theory and left-handed anti-neutrino

I calculated the $\mu \rightarrow e^- + \nu_{\mu} + \bar{\nu}_{e}$ both in Fermi's theory (V-A) and Intermediate Vector Boson theory and IVB at first order seems to match with Fermi's theory which is ...
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Quick question about $\nu_{\mu} + e^{-} \rightarrow \nu_{e} + \mu^{-}$ scattering in intermediate vector boson theory

Below I added a diagram representing the $\nu_{\mu} + e^{-} \rightarrow \nu_{e} + \mu^{-}$ process and the corresponding Feynman amplitude: Please ignore the typo $k^2 = t^2$. It is $k^2 = t$ I know ...
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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 ...
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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 ...
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How can I solve the EDO for the neutrino oscilattion case using runge-kutta?

I would like to solve the EDO for the Neutrino Oscillation case using the Runge-Kutta method. So, suposse that I have the following system: $i\frac{dy}{dt} = Hy$ where $H$ is the Hamiltoniam of my ...
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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 ...
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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 ...
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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 ...
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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 ...
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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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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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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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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?
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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 ...
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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 ...
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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|...
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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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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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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 ...
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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 ...
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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 ...
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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 ...
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What, exactly, is meant by 'effective number of neutrino species'?

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 ...
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