Neutrinos Definition and 329 Threads

Would neutrinos emitted in the distant and early universe be slowed enough to become thermal neutrinos? Could these be detected?

Hello I was reading in Griffiths that in the case of electron neutrino scattering, one can apply Casimir's trick to sum over input and output spin states, including the neutrinos. My question is, how come you are allowed to include in the sum the nonphysical right handed helicity state ? And...

Neutrinos were flavor eigenstates at the time of their decoupling from baryonic matter. Since they were not pure mass eigenstates, how do you take this fact into account if you try to study how they evolved as the universe expanded? Could we determine if the heaviest neutrino could be non...

i found reading the possible interaction of neutrinos with photons to not "level tree", what's the meaning of level tree? and how is that posibble ?

In one step of the solar ppII chain the following reaction (may) take place: ⁷Be + e⁻ --> ⁷Li + ν_e This reaction was used in the famous homestake experiment to detect solar neutrinos when the famous solar neutrino problem came into play. In...

The new fermilab video ends with a teaser: Do right-handed neutrinos exist or is it that they do not interact with matter? (at 7:30) For those of us who cannot wait for the next video to find out, is there a clear answer?

Ordinary Standard Model neutrinos _are_ dark matter particles, in a sense that they have mass, and they only weakly interact with everything else. IIRC they are not considered to be a satisfactory candidate because nearly all neutrinos in the Universe are relativistic, whereas we know that...

So we are not yet sure exactly what mechanism accounts for the neutrino masses. One possible mechanism is the seesaw mechanism. Am I correct in thinking: Majorana mass terms are born from couplings between particles and antiparticles. This violates lepton number conservation and charge...

This question just occurred to me recently. Assuming the different neutrinos (electron, muon, tau) do not have the same mass, then if their energy is very low, such that they are moving non-relativistically, an oscillation must substantially change the velocity (to conserve momentum). It seems...

Neutrino oscillation seems to have as one of its prerequisites the fact that the flavour eigenstates differ from the mass eigenstates, so the time-dependent Schrödinger equation applies. Can a neutrino "drop" into the lowest mass eigenstate (which is also the lowest eigenstate of the...

Although I do not have the technical qualifications to understand to mathematics of quantum field theory, I happened to come across a preview of a book called The Electron by Dennis Morris on Amazon. While reading the preview I came across this sentence: "The solution of the neutrino mass...

The theory of cosmology assumes that the universe has been created from a single point by one big bang event. This theory implies processes which exceed the speed of light. <<Mentor note: This post has been edited to remove some content.>>

To determine the mass of charged leptons, we rotate such that the matrix of yukawa couplings (which gives the mass matrix after EWSB) is diagonal. We also call this flavour basis for neutrinos, because the flavoured neutrinos couple directly to the correspondong flavoured lepton in weak charged...

I've read that if right-handed neutrinos exist, they should be heavier than left-handed neutrinos (why?). I figured if an observer moves faster than a left-handed neutrino, he'd see it as right-handed. Also, would right-handed neutrinos interact with Z-bosons? How would such interactions be...

I'm an A level student currently trying to understand the behaviour and properties of neutrinos, and wanted to check that I've understood the basics of neutrino properties. As neutrinos are half-integer spin particles, can the Fermi-Dirac distribution be used to calculated the probable...

The following article is interesting to me, however particle physics is not one of my strong points, could anyone comment on it and its implications regarding the early universe? Thanks. http://www.bbc.com/news/science-environment-36776167

Assume just for this question that a neutrino has a mass of 1 ev. That is about the energy of an infrared photon with a wavelength of 1 micron. Is it possible for a visible light photon, or a more energetic photon, to create a neutrino-antineutrino pair?

@mfb mentioned in a thread about dark matter how neutrinos don't conglomerate in galaxies and it got me wondering where they are. Considering that they move at nearly the speed of light, I understand why they couldn't be captured by galaxies, but what about large scale structures? Do neutrinos...

Hi guys In an assignment I wrote for university I was penalised for claiming that FTL neutrinos would violate special relativity. Below is the relevant part of my assignment and the response from my lecturer. Could somebody please explain what he could mean by that because as far as I can...

I'm learning about beta decay and as I understand in beta decay we get: neutron → proton + electron And since all these have spin 1/2 we have that the conservation of angular momentum is not conserved. The neutrino with spin 1/2 is proposed to also exist in the process to solve this so that...

In the wave-packet approach, different neutrino mass eigenstates have different mass and thus propagate with different speeds. This will eventually lead to wave-packet separation and decoherence. My question is, can neutrinos be produced/detected incoherently? (In other words, can different...

I am wondering... And I may be wrong but please correct me... In general we have some constraints on the masses of the 3 flavored neutrinos m_{\nu_e}, m_{\nu_\mu} , m_{\nu_\tau} and so there must be some constrain on the values of the 3 neutrino masses m_1, m_2, m_3. Am I right? Also the...

Compared to the other fermions, I have always had much less interest in Koide mass formulas for neutrinos. There is less data, and neutrino mass works differently anyway (Dirac plus Majorana, whereas the other fermions are just Dirac). But today that has changed. First, today we have a paper...

When I first heard about the OPERA apparent superluminal results on the measurement of neutrinos speed, I tried to locate an explanation using all the possible relativistic effects. All were too small to account for a difference of 18 meters of virtual distance among photons and neutrinos. Then...

Hi All 1. Homework Statement with the known coupling strenght between SM neutrinos and Z boson Z_{\mu} \bar{\nu}_{L} { \gamma}^{ \mu} \nu_{L} how can I get the coupling strength for Dirac neutrinos Z_{\mu} \bar{\nu}_{Dirac} { \gamma}^{ \mu} (1- { \gamma}_{ 5} ) \nu_{Dirac} ? thanks

beneath all problems with gravitons to describe mathematically (simple said our idea of a graviton is a gluon with spin 2 which is only predicted through CFT in 5 dimensional AdS) we have another problem mathematically to describe. We found 3 generations of neutrinos with mass through...

The Nobel Prize in Physics 2015 was awarded jointly to Takaaki Kajita and Arthur B. McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass" So I was wondering if they have mass how fast are they traveling?

They make fluorine, according to a large new study. Link: ScienceNOW

http://inspirehep.net/record/1382926?ln=en PRL, 8 pages, 4 figures +supplementary material most neutrinos IceCube detects originated locally---e.g. from cosmic ray particles hitting Earth's atmosphere. But extra high energy neutrinos are more likely to come from outside solar system. As I...

Most presice measurement to date done by MINOS of neutrino time of flight through Earth published two days ago, once again found neutrinos slightly faster than light speed within statistical errors. Only when they extend the band with systematic errors doesn't neutrinos surpass light speed...

Can someone help me understand the following figure? It shows how the conversion of neutrons (electron neutrinos=red, muon neutrinos=blue) is happening through the Sun for different cases of the core's density (relative to the resonance density). I only understood the top figure, which tells...

I am confused about the current physics regarding neutrinos and implications about the conservation laws of mass-energy and linear momentum. I have read the threads listed for similar discussions, including, "How does conservation of energy/mass apply to neutrinos?", and none of them seem to...

Homework Statement Neutrinos with energy of about ##1 GeV## are measured in an underground detector and compared with simulations of neutrinos produced in the atmosphere. Measured flux of upward going muon neutrinos ##(\nu_\mu + \bar \nu_\mu)## is half compared to simulations while measured...

Can a neutrino undergo elastic collision with a particle participating in weak interaction, such as an electron, a nucleon, or other lepton or a hadron, such that the direction of neutrino movement changes by 180 degrees? If yes, what is the direction of the neutrino spin relative to its...

Dear PF Forum, I once read in several links just a couple of days ago, that the number of neutrinos exceeds the number of baryon in the universe by several orders of magnitude. 1. Is that true, that neutrinos are much more abundant than atoms? 2. Do neutrinos have mass? Not that they are...

We know that there are 3 generations of neutrinos, namely the electron neutrino, muon neutrino and the tau neutrino. The masses are all very small compared to their respective leptons. What evidence is there that these neutrinos of different generations are distinct?

If we consider de right-handed neutrino there would be more anomaly-free solutions than hypercharge for a U(1)?

The folowing quote is from a Wikpedia article https://en.wikipedia.org/wiki/Neutrino . "From cosmological arguments, relic background neutrinos are estimated to have density of 56 of each type per cubic centimeter and temperature 1.9 K (1.7×10−4 eV) if they are massless, much colder if their...

I'm obviously studying about neutrinos lately... So, I wanted to ask about the Glashow resonance. I don't understand what they mean when saying: http://arxiv.org/pdf/1108.3163v2.pdf (sec.2) Unfortunately I don't have access in the refs. If I understand this correctly, it says that the...

Relic neutrinos decoupled from matter around the time of nucleogenesis so had the same temperature as matter and photons at that time. Photons decoupled much later, after electron/positron annihilation which heated the photons slightly so thereafter neutrino temperature should be (4/11)^(1/3)...

Dirac description If I well understood a Dirac description for fermions is : ##\Psi_{D}=\Psi_{L}+\Psi_{R}## where ##\Psi_{L}## is the left-chiral spinor and ##\Psi_{R}## the right-chiral spinor. Each spinor, ##\Psi_{L} ## and ##\Psi_{R}## has 2 components cotrresponding to the particle and...

How would fusion processes be affected, by a background bath / sea of neutrinos ? Would the constant interactions between fusion products, and neutrinos, constantly break apart the fusion products, and so tend to "undo" the fusion?

Hey guys! How can this sentence be explained and what does it mean? If the couplings $$Z\nu_{\alpha}\bar{\nu}_{\beta}$$ of the neutral intermediate boson to neutrinos are flavor preserving, they are also diagonal when expressed in terms of mass eigenstates $$Z\nu_{i}\bar{\nu}_{j}.$$

A left handed neutrino (chirality) can be seen with a right helicity due to a lorentz boost. Can this neutrino interact ? Yes because it is still left-handed chirality ?

My question concerns the chirality vs helicity for massive neutrinos. I know that as the mass is really light we can usually approximate helicity = chirality. But I would like to consider the exact case with the mass : i.e left handed (chirality )neutrino propagates with both left and right...

I am trying to explain why why the survival probability for solar neutrinos is different for different neutrino solar lines, and what causes this difference.

This isn't really my area (I'm a mechanical engineering graduate), but I thought maybe somebody on the forum could give me feedback or help redirect my thinking if this is not right. So, neutrinos are famous for not really doing anything, just kind of being there (by this I mean being the...

Suppose you have a source of electron antineutrinos, and you arrange your apparatus so that a billion billion billion of them collide directly with a black hole. In principle, you could measure the change in momentum and energy from that occurrence. Suppose you did that the next day. According...

<<Mentor note: This post and its answers were moved from this thread.>> How do you reconcile a superposition of flavors, with different masses, with conservation of energy and of momentum? Say the rest masses of three flavors are known, and you want to measure the velocity of the neutrinos...

How massive would the neutrinos have to be so that relic neutrino from the big bang would account for all dark matter?