3
votes
3answers
38 views

Isotropic neutrino-lepton scattering

I'm a physics student and I'm attending an introductory course of particle physics. My professor stated that, in center of mass frame, the $\nu_\mu e^- \to \nu_\mu e^-$ elastic scattering has an ...
6
votes
2answers
59 views

Double decay $\beta\beta$ observation and neutrino mass

If the double decay $\beta\beta$ will be detected this means the neutrino is a Majorana particle coincident with its antiparticle. At the moment the half life of this decay is put to ...
7
votes
1answer
122 views

What is chirality?

I actually wanted to make the title as "What is the difference between chirality and helicity"? But I didn't do that because I don't understand properly what chirality is. I have gone through this ...
1
vote
3answers
124 views

Solar neutrino problem in 1968 and experimental verification of neutrino oscillation in 2001. Why the huge delay?

Solar neutrino deficit was first observed in the late 1960's. And theory of neutrino oscillation was developed in 1967. But,in 2001, the first convincing evidence of solar neutrino oscillation came in ...
4
votes
1answer
69 views

Put yourself in the shoes of Wolfgang Pauli (1930): How could Pauli have narrowed the culprit down to one particle, instead of many?

A while ago, during my introductory physics course, my professor purposefully neglected to tell us about the existence of the anti-electron neutrino in beta decay; he made it an assignment(on our ...
4
votes
3answers
328 views

Does the Standard Model require neutrinos to be massless?

I am an undergraduate student in Physics, I have a basic understanding of Particle Physics and Quantum Mechanics but none whatsoever of Quantum Field Theory. I know that Neutrino mixing requires ...
16
votes
3answers
1k views

What exactly is an anti-neutrino?

According to the the definition of anti-particles, they are particles with same mass but opposite charge. Neutrinos by definition have no charge. So, how can it have an anti-particle?
1
vote
0answers
42 views

Mass eigenstate of neutrinos [duplicate]

Isn't mass a fixed and an intrinsic property of a particle? How can we talk about eigenstates of the mass in the context of neutrinos?
3
votes
1answer
92 views

Why are neutrino and antineutrino cross sections different?

Particularly in the case of Majorana neutrinos, it seems a little odd that the particle and antiparticle would have differing cross sections. Perhaps the answer is in here, but I've missed it: ...
3
votes
1answer
104 views

What is the meaning behind the neutrino oscillation parameter?

As far as I can tell, there are 6 parameters that describe how a neutrino oscillates: 2 mass squared differences, 3 mixing angles and another parameter I don't understand at all (delta). Thus I have ...
2
votes
0answers
43 views

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; ...
3
votes
3answers
130 views

Unitarity of PMNS matrix

Why should the neutrino mixing matrix (PMNS matrix) be unitary? Is the unitarity dictated by experiments or is it a theoretical demand?
3
votes
1answer
83 views

Majorana Mass For Neutrinos In Standard Model

Neutrinos can't be given Dirac masses because there is no $SU(2)_L$ singlet right handed neutrinos in the standard model. But can neutrinos be given Majorana masses in the standard model? EDIT: Why ...
0
votes
0answers
70 views

Oscillations and Majorana Neutrino

In neutrino oscillations, neutrinos can convert from one flavor to another. This implies individual lepton number is not conserved. Doesn't it also imply that, if the neutrinos have mass, the mass ...
1
vote
2answers
144 views

Question about Majorana fermion and Majorana representation

In Chiral representation, a Majorana spinor looks like: $$\psi=\begin{pmatrix} \psi_L\\ -i\sigma^2\psi_L^*\end{pmatrix}$$ In this representation the Right handed field is the charge-conjugate of ...
1
vote
0answers
72 views

Confusion With Neutrino Oscillation

Neutrinos produced in the weak interaction are eigenstates of the weak interaction hamiltonian or flavor eigenstates. Right? If this is so, then $\nu_e,\nu_\mu,\nu_\tau$ should be the stationary ...
1
vote
0answers
51 views

Writing Dirac Mass Term For Massive Neutrinos

How does one write down the following Dirac mass term for a collection of "massive" neutrinos? \begin{equation} -[\overline{(\psi_R)}M_D\psi_L+\overline{(\psi_L})M^\dagger_D\psi_R] \end{equation} I ...
3
votes
2answers
97 views

Neutrinos and anti-neutrinos in the Standard Model

In standard model neutrinos and the left handed electron forms SU(2) doublet. What about the anti-neutrinos in the standard model? Do they also form some doublet? If neutrinos have tiny masses will ...
1
vote
1answer
52 views

Fusion of two neutrinos

What are the results of fusing an electron neutrino and a muon neutrino? If you have an answer, then why? I looked this up and searched for stuff on Google, Wikipedia and a few other sites, but all ...
5
votes
1answer
103 views

Sterile Neutrinos and Supersymmetry

Just read a Scientific American review of a recent article which suggests evidence for sterile neutrinos: ...
4
votes
2answers
123 views

Do neutrinos not couple to the Higgs field?

I was reading the CernCourier, my favorite source of message on Higgs and friends. I was rather shocked, when I saw this: "The mechanism by which neutrino mass is generated is not known." What? ...
1
vote
1answer
120 views

Massless neutrinos and Chirality

The massless neutrinos can be represented by two component Weyl spinors. Then how does one say that it is an eigenstate of the chirality operator $\gamma^5$, which is a $4\times 4$ matrix and can act ...
2
votes
1answer
153 views

Why positronium can annihilate in vacuum?

I thought that the annihilation process of positronium cannot take place without a third-party particle. This can be directly derived from energy & momentum conservation: energy conservation: ...
2
votes
1answer
267 views

What are mass eigenstates?

According to Wikipedia Neutrino oscillation arises from a mixture between the flavor and mass eigenstates of neutrinos. That is, the three neutrino states that interact with the charged leptons in ...
10
votes
1answer
155 views

The delay between neutrinos and gammas in a supernova, and the absolute mass scale of neutrinos

In a supernova explosion (of some type), there is a huge amount of neutrinos and gamma rays produced by a runaway nuclear reaction at the stellar core. In a recent comment, dmckee noted that the ...
5
votes
1answer
105 views

What sorts of complications do massive neutrinos bring to the Standard Model?

Naively, I'd just think of considering them as any other massive fermions (but without electric charge), including the appropriate chiralities (and neutrino-higgs coupling when necessary). ...
4
votes
2answers
168 views

Pair production of neutrinos

I learned that neutrinos have a much lower energy than electrons. Pair production of electrons occurs when the photon energy is above 2 times the energy of an electron. So I am wondering if pair ...
-1
votes
1answer
57 views

Statistics followed by Neutrinos [closed]

What does the neutrino particles follow- Dirac or Majorana Statistics?
5
votes
1answer
155 views

Question about Neutrino Flavor and Mass Eigenstates

I know the flavor and mass eigenstates are different, but are they related? What I mean is, in a process like fusion where electron neutrinos are created, do they start in the 1 mass eigenstate? My ...
2
votes
1answer
99 views

How quickly do neutrinos change flavor?

DOE’s Fermilab has switched on its newly upgraded neutrino beam. This is in preparation for the NOvA experiment, which will study neutrinos using a 200-ton particle detector at Fermilab and a ...
2
votes
3answers
103 views

Controlling Neutrinos for Communication

Neutrinos travel straight through earth at the speed of light. Therefore, it seems that they could be great for intercontinental communication. Of course, I assume a lot still needs to be learned ...
1
vote
0answers
77 views

Neutrino power plant

Suppose there is a material that interacts with 50% of high-energy neutrinos. To what temperature such material will heat up naturally here on Earth? What power can be extracted from it?
1
vote
2answers
198 views

Slowing down high energy neutrinos?

Which atoms can slow down high energy neutrinos? I mean in which medium high energy neutrinos will tend to slow?
1
vote
2answers
201 views

Neutrinos: how can they carry information about universe?

I know that neutrinos are particles with a very small mass and no electric charge. They infrequently interact with matter and so they can give us information about the "old" universe. But how can they ...
0
votes
0answers
40 views

Why aren't there more than three generations of the leptons and quarks? [duplicate]

There are three generations of electrons, neutrinos, and quarks. The second and third generations of electrons and quarks are unstable and decay into lighter particles. Why are there exactly three ...
5
votes
2answers
654 views

Do neutrinos of any flavor get trapped in black holes?

This question has been bothering me a bit. I know that neutrinos have super small mass and they interact via the weak force. Since they have a non-zero mass, they should be affected by black holes and ...
2
votes
2answers
246 views

How much energy is carried away by neutrinos in matter-antimatter annihilation?

Some people say that neutrinos carry away most of the energy, some others say just a fraction. So what is the truth ? what is the percentage of energy lost due to neutrinos ?
5
votes
1answer
280 views

Mechanisms of mass generation for Dirac neutrinos

If neutrinos are Majorana particles, one way of explaining their small masses is the seesaw mechanism. Now say I'd like my neutrinos to be Dirac, for symmetry to the quark sector. What mechanisms ...
3
votes
2answers
516 views

What is difference between the different 'flavours' of neutrinos?

Moreover, how-come scientist know that muon-neutrino are different from electron-neutrino when they didn't even know what the difference was? Did they interact differently with other particles?
2
votes
1answer
266 views

Neutrino mass with Dirac and Majorana

Why both Dirac mass and Majorana mass terms are needed to explain the mass of a neutrino?
10
votes
1answer
385 views

Are right handed neutrinos actually antineutrinos and vice versa?

Is it experimentally ruled out that right-handed neutrinos are actually antineutrinos, and left-handed antineutrinos are neutrinos ?
3
votes
1answer
138 views

Neutrino Oscillation and their gravitational implications

As I understand neutrinos, there are three different flavors, all with different masses. Although the masses of these neutrinos have not been directly measured, their mass differences have been. ...
0
votes
1answer
158 views

“Conceptualizing” neutrinos

Layman here. EE and BS physics. I am "content" in viewing photons/electromagnetic radiation as an "emergent" property of spacetime? due to the electrons ("particles..?") and all their activity jumping ...
1
vote
2answers
397 views

Neutrino and electromagnetic forces

I learned from Wikipedia that neutrinos "are not affected by the electromagnetic forces". How was this identified experimentally?
10
votes
1answer
441 views

Neutrino Oscillations and Conservation of Momentum

I would like to better understand how neutrino oscillations are consistent with conservation of momentum because I'm encountering some conceptual difficulties when thinking about it. I do have a ...
5
votes
1answer
134 views

Are there any reasonable attempts at explaining the OPERA result

as there's so many papers on the opera result and it's a struggle flicking through them all combined with my limited knowledge meaning I cannot well differentiate silly nonsensical papers from ones ...
25
votes
4answers
2k views

How do we know Dark Matter isn't simply Neutrinos?

What evidence is there that dark matter isn't one of the known types of neutrinos? If it were, how would this be measurable?
4
votes
2answers
346 views

Where did the idea of a neutrino come from?

Exactly what paper by W. Pauli introduced the idea for the existence of a neutrino and how was its existence confirmed experimentally (who did that and in what paper)?
6
votes
2answers
214 views

How is the distance between Geneva detector and the Gran Sasso one measured?

Does anyone know how is the distance between detectors in the now famous neutrino experiment measured? Also, how was the time of flight measured?
13
votes
1answer
350 views

How are neutrino beams emitted at CERN?

As far I know they come from accelerator collisions, but I have read confusing things like magnetically focused. How could neutrinos be guided magnetically if they aren't affected by the ...