All Questions
Tagged with beyond-the-standard-model neutrinos
30 questions with no upvoted or accepted answers
2
votes
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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 ...
2
votes
0
answers
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
2
votes
0
answers
32
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What is the difference between these mixing-angle equations?
In the following article the mixing angle of the neutrinos is given by:
$$\sin^2 2\theta = \frac{\mu^2}{\mu^2 +[c\Gamma_\alpha E /M +M/2]^2} \tag{1}$$
where $\mu$ represents the Dirac mass , M ...
- 109
2
votes
0
answers
45
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Why would the damping factor of neutrino oscillations be negligible?
In this article the Boltzmann equation for the sterile
neutrinos is simpified to this form:
$$\frac{\partial}{\partial t} f_s (p,t) -H p \frac{\partial}{\partial p} f_s (p,t) \approx \frac{\Gamma_\...
- 759
2
votes
0
answers
347
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Why a neutrinoless double beta decay implies a massive neutrino?
I know neutrinos have mass thanks to the observation of the neutrino oscillations between one type to another (that cannot happen if they are massless particles because the mixing matrix will not ...
- 930
1
vote
1
answer
64
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Right-handed neutrinos as dark matter and neutrino bounds
How can right-handed neutrinos evade the SM experimental bound $N_\nu=3$ and become all the dark matter?
- 6,727
1
vote
0
answers
681
views
What would a standard model that incorporates the SMASH particles look like?
I'm trying to create a standard model which incorporates the SMASH (Standard Model Axion Seesaw Higgs portal inflation) particles, but I'm having a hard time doing it because I'm unable to find as ...
- 136
1
vote
0
answers
46
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Possibility of reaching equilibrium starting with a nonequilibrium initial condition in the early radiation-domination
Update after @knzhou's comment
If in a theory, the coupling of the dark matter (DM) field to the Standard Model (SM) fields is small enough, the rate of interaction of the DM particles in the ...
- 27.2k
1
vote
0
answers
37
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Is this equality based on the HDM true?
It is stated in Sterile Neutrinos as Dark Matter that in the HDM model: $$\frac{\mu^2}{m_s}= 92 h^2 \text{eV} \tag{1}$$
where $m_s$ represents the mass of sterile neutrinos and $\mu^2$ represents the ...
- 759
1
vote
0
answers
177
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How to give left-handed neutrinos alone Majorana mass?
The Wikipedia page on Georgi–Glashow model says
Fermions transforming as a 1 under SU(5) are now thought to be necessary because of the evidence for neutrino oscillations, unless a way is found to ...
- 4,376
1
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0
answers
71
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Is it possible that are particle is much heavier through a loop correction?
Let's assume, we have standard model singlet particle $s$, that mixes after electroweak symmetry breaking with an exotic, vectorlike neutral lepton $N$. The relevant part of the Lagrangian reads
$$ L ...
- 10.3k
1
vote
0
answers
217
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Calculation of mixing angle and mass squared difference in neutrino experiments
How is an exclusion curve/contour plotted in $\Delta{m^2}$ - $\tan(\theta)$ plane from a given experimental data and how the best fit value of $\Delta{m^2}$ (mass squared difference) and $\theta$ (...
user142201
1
vote
1
answer
116
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Can the Mikheyev-Smirnov-Wolfenstein (MSW) effect be modified by non-standard neutrino-neutrino interactions?
The MSW effect describes how propagation of neutrinos through matter can resonantly enhance the neutrino mixing. The reason for this enhancement is that the presence of electrons in matter changes the ...
- 1,803
1
vote
0
answers
131
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Can a neutrinos mass oscillate in a similar way to its flavour?
So I've been reading up on neutrino oscillations and I think I'm making some progress in understanding it, but I'm still a long way off. As I understand it, you can 'classify' neutrinos in two ways; ...
- 71
1
vote
1
answer
673
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Right-handed neutrinos in Standard Model
Does SM allow for the right-handed (Majorana) neutrinos? Or right-handed neutrinos are beyond SM?
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
0
votes
0
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41
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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
42
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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 ...
- 377
0
votes
0
answers
125
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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 ...
- 131
0
votes
0
answers
134
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Mass matrix for inverse seesaw mechanism
I am having trouble in diagonalizing analytically the mass matrix associated to the inverse seesaw mechanism with lagrangian:
$L= -y_1\bar{L}\tilde{H}N_{R_1} - -y_2\bar{L}\tilde{H}N_{R_2} + N_{R_1}^...
0
votes
0
answers
45
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Sterile neutrinos on a theoretical point of view
The results at the BEST experiment strongly suggest that at least one "sterile neutrino" exist.
From the way the experiment is done it is obvious that only the lighter sterile neutrino can ...
- 4,448
0
votes
0
answers
132
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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 ...
- 53
0
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0
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79
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CP violation phases counting in neutrino flavor mixing sector with $N$ sterile neutrinos
In the quark sector, the CKM matrix is obtained from (see p.723 of Peskin QFT)
$$
V_{CKM} =U_u^\dagger U_d = \begin{bmatrix} V_{ud} & V_{us} & V_{ub} \\V_{cd} & V_{cs} & V_{cb} \\
V_{...
- 4,376
0
votes
0
answers
85
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Flavor mixing Higgs Yukawa term with both left and right chiral neutrinos and with generic masses
In p.727 of Peskin QFT, it derives a flavor mixing Higgs Yukawa term, but he assumes that the neutrinos have no mass.
However we know that we can include both left and right chiral neutrinos, and also ...
0
votes
0
answers
51
views
What is the reheating temperature of neutrinos during the BBN?
I want to integrate a differential distribution function of sterile neutrinos and the boundaries are the decoupling and the reheating temperature of neutrinos, but I don't know what is an acceptable ...
- 759
0
votes
0
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58
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Neutrino oscillations
It seems well documented that neutrinos oscillate between flavours. In the link there are some figures which show probabilities but it isn't clear to me why the abscissa is measured in $L/E$. Is it ...
- 3,906
0
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0
answers
27
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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}...
0
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48
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About the experimental measurement of neutrino magnetic moment and its value
Massive neutrinos, be it Dirac or majorana, have magnetic moment. See here, here and here.
$\bullet$ How is it measured (or can be measured) in real experiments? What are the (upper and lower) ...
- 27.2k
0
votes
0
answers
96
views
Theoretical supporting factors to consider neutrinos are majorana type particles or dirac type particles
What are the theoretical supportive factors to consider neutrinos as Dirac fermions? What are the theoretical supportive factors to consider neutrinos as Majorana fermions?
- 145