Fermilab Confirms Evidence of 4th Flavor Neutrino 122
eldavojohn writes "We've only had evidence for three kinds of neutrinos so far, but a recent test at Fermilab involving an antineutrino beam has reinforced a Michigan researcher's earlier experiment suggesting a fourth flavor. What's really odd about this is that a prior neutrino test (carried out as part of project MiniBooNE) did not result in indications of such strange oscillations. According to the researcher, 'The simplest explanation involves adding new neutrino-like particles, or sterile neutrinos, which do not have the normal weak interactions.' But this could also be an unknown or misunderstood effect. A Los Alamos National Laboratory scientist added that an explanation of this strange anomaly could result in understanding 'matter asymmetry of the universe, or why the universe is primarily composed of matter, rather than antimatter.' The results are published in the Physical Review Letters."
Cool (Score:2, Funny)
Re:Cool (Score:5, Funny)
Yes, but you're never going to get one to hit your taste buds.
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Billions of them pass through your taste buds every second. The problem is getting them to interact with your taste buds.
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I think "Not Interacting" with my taste buds is the same as never hitting my taste buds.
Re:Cool (Score:5, Funny)
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You're left with nothing but dust...
Re:Cool (Score:4, Funny)
Billions of them pass through your taste buds every second. The problem is getting them to interact with your taste buds.
So, they have no calories!
I'm on the neutrino diet plan now. I just need to get booked on "The View" and I'll be rich!
Move over Atkins, here comes the Neutrino Diet!
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Nah, they all taste just like chicken.
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Raise your hands, everyone who read that as Large Hardon Collider. Ok, raise your free hand.
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If a chicken flavor neutrino travels through the earth and interacts with a Chinese taste bud, then is the effect gone in 30 minutes?
as foretold by Al Jaffee (Score:2)
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wel... (Score:1)
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Is it? I hardly know what that means.
Those guys at CERN have ultimate job security - no one will know what they're doing beside them and they can keep claiming breakthroughs indefinately.
Re:wel... (Score:4, Informative)
Re:wel... (Score:5, Funny)
Those guys in white coats all look alike to me.
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Neutrinos, livers... it's all the same thing to you, eh?
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Re:wel... (Score:5, Funny)
The only physicists I've ever seen in lab coats were in angles and demons.
Angles? Were they so acute they were obtuse?
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The only physicists I've ever seen in lab coats were in angles and demons.
Eeeagh! The non-Reimannian manifolds! They are coming THROUGH the door!
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Real physicists wear suspenders!
Real physicists wear THE SAME suspenders EVERY DAY.
Here, fixed that for you
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They're waiting for you, Gordon, in the tessssst chaaaaaamber.
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No they aren't, but I bet they have enough luminousity in their beam to make reconfirmation a bit easier. Maybe they'll shoot a neutrino beam at the detector;
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No, but depending on the characteristics of this new flavor (Aparently more unstable than the 3 known flavors, due to scacity in detecting them) they might decay into more mundane neutrinos while in transit.
Now, a worthwhile experiment would be to generate neutrinos at CERN, detect a sample in the CERN collector, then have that same stream collected at FermiLab, and compare sample populations as recorded by the two detectors. That would give you some more hard data concerning rates and specificities for ne
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Neutrinos interact so infrequently with normal matter that attenuation wouldn't be a problem, perhaps collimation would pose challenging. Right now Fermilab is shooting neutrinos through a 1000 kilometers [fnal.gov] of dirt and rock.
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Wooosh? Oh you think the "flavour" of neutrino and "sweet" joke went over my head?
No - EVERYONE made that joke.
Fourth flavor (Score:3, Funny)
Sorry, I spilled my Fun Dip packet [wikipedia.org] in there...
Department win (Score:5, Funny)
Re:Department winur (Score:5, Funny)
No, no, no the neutrino flavors follow the same pattern as basic emotions: Happy, sad, approving, disapproving and umami. Umami is a relatively recently discovered emotion. It feels like broth.
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It feels like broth.
I thought LSD went out of style in the '70s
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I think he means that it feels warm, wet, and gets sticky as it dries. (Of course, many other things beside broth do this too, but we were discussing broth here.)
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What happened to the other 31 - 4 = 27 Flavors?
Heim Theory? (Score:2)
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Now, IANAPP (particle physicist), but I thought one of the things discrediting Heim Theory [wikipedia.org] was the prediction of more than 3 neutrinos. What does the presence of a fourth neutrino mean for other predictions made by the current model? Does this mean that Heim's predictions may have more credence?
I think the bigger issues would be the wildly incorrect values for extremely well-known parameters (90ish sigma away from the measured mass of the proton, for instance) and the prediction of a "neutral electron" at a mass that should make it appear in pretty much every particle physics experiment EVAR.
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This is big problem in
From what I can tell (Score:3, Informative)
Re:Heim Theory? (Score:5, Informative)
This is what the Standard Model calls a neutrino. And there are, in fact, only 3 kinds. This was shown pretty convincingly by LEP at CERN [cerncourier.com]. And it's also enough to discredit Heim's Theory (which no one really took seriously in the first place).
What this story is suggesting is that there may be a different kind of neutrino -- a so-called "sterile neutrino" -- that doesn't even feel the weak force. This isn't part of the Standard Model, but it is possible in certain extensions of the SM. This kind of neutrino doesn't act the same way as the SM neutrinos; it's a different beast, and comes about through a different part of the mathematics.
Re:Heim Theory? (Score:5, Interesting)
Since you are a /former) particle physicist, maybe you can explain me why it's not considered entirely natural that there are neutrinos which don't interact with the weak force. My consideration is the following: For each particle except the neutrino there are left-handed and right-handed versions. Only for neutrinos, only left-handed have been observed. Now what would a right-handed neutrino look like? Well, obviously it would not interact strong or electromagnetic, because after all it's a neutrino. But it also wouldn't interact weak, because it's right-handed. This would explain why it wasn't observed in experiments (because AFAIK Neutrinos are always observed through their weak interaction). On the other hand, it would interact gravitationally, and would therefore make a form of dark matter, without any extension to the standard model, except that one would drop the claim that there are only left-handed neutrinos. Since it seems strange anyway that neutrinos, unlike all other particles, only come in left-handed form, I'd expect that a "sterile" right-handed neutrino would be the natural assumption.
However the fact that particle physicists don't assume that, I guess there are good reasons not to assume it. So what is the problem with this reasoning? And could the sterile neutrino from this story be actually such a right-handed neutrino?
Re:Heim Theory? (Score:5, Informative)
You're right in that a right-handed neutrino would interact only gravitationally. But if they exist, how did they get created in the first place? That creation process had to involve some combination of the other 3 forces -- gravity doesn't allow for particle creation or decay.
Another thing is that if it were massive (and it would have to be), it would have to have a left and right-handed component, and be invariant under Lorentz transformations. (One way to think about it is this: If it's moving in a certain direction, you could look at it from a reference frame moving even faster in that direction, and it would appear to be going the other way. This would change it from a right-handed to a left-handed particle, which would mean it could interact with the weak force, etc. etc. So it would have to be a mixture of both left- and right-handed components - you can't have a purely right-handed neutrino with a non-zero mass).
It also turns out (mathematically) that you can construct a (sterile) neutrino by using only left-handed fields, and still make it behave as if it had a right-handed component. This is the so-called "Majorana spinor". So you don't really need to invoke right-handed neutrinos, you can get the same result using just the left-handed fields.
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Isn't Hawking radiation a process where gravitation creates particles?
Also, since Neutrons have nonzero mass, wouldn't they also interact with the Higgs boson? Could the Higgs boson allow creation paths? Maybe a Higgs particle decays
Re:Heim Theory? (Score:4, Informative)
Isn't Hawking radiation a process where gravitation creates particles?
Not really. It's an electroweak process that actually creates the particle-antiparticle pair.
Maybe a Higgs particle decays into a right-handed neutrino and something else?
No. "Decay" implies a weak interaction. And the weak force only interacts with left-handed particles (or more precisely with the left-handed fields, or components, of a particle).
The Higgs field can couple the left- and right-handed fields of a particle. But when you're talking about "Higgs particle decay", that's a weak interaction, which is only left-handed.
IIUC, if left-handedness depended on the frame of reference, then whether an electron (which very clearly has mass) can interact weakly would also depend on the frame of reference, and that doesn't make sense to me.
That's why you can't have a purely left- or right-handed massive particle. Any massive particle (like an electron) has to have both a left-handed and a right-handed (chiral) component. It also has to be invariant under Lorentz transformations, meaning that as you change reference frames, the particle looks the same. Only massless particles can be purely left-handed or right-handed, and for them chirality and helicity [wikipedia.org] are equal. But not for massive particles.
By the way, the evidence of neutrino oscillations means that the three Standard Model neutrinos must have some non-zero mass, which means they're not purely left-handed. They were once thought to be purely left-handed, but that was when they were thought to be massless. Now we know that they're more like electrons, with a left- and right-handed component.
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Refresh your knowledge! You shouldn't be confusing chirality with helicity. You can change helicity by boosting to a faster moving frame of reference, but not chirality. Chirality is related to how the spinor transforms under Lorentz transformations. Both are the same in the ultra-relativistic limit (ie. 0 mass).
Weak interactions couple only to left-handed (as in chirality) spinors. There's no way you can change that with a Lorentz transformation, you would get ugly paradoxes if that were the case. Like the
Any sufficiently advanced particle physics... (Score:3, Funny)
This is why I love particle physics. I am a scientists by training, but not a physicist, and while I have the sense that you two are not speaking gibberish, I can't be sure :) Or to put it another way, to paraphrase Arthur C. Clarke, "Any sufficiently advanced physics is indistinguishable from gibberish."
Answers (Score:5, Informative)
So what is the problem with this reasoning? And could the sterile neutrino from this story be actually such a right-handed neutrino?
First: it cannot be dark matter because neutrinos are too light and hence move too fast. The result is that the WMAP cosmic microwave background would be blurred out far more than it is so we know that, whatever the dark matter is, it is slow moving and so not a light neutrino.
Second: MiniBoone has interesting results but have not BY ANY STRETCH of the imagination confirmed the existence of a 4th gen of neutrinos. Their signal is only 0.6% incompatible with background. To claim evidence the standard in the field is 3 std. dev. (or 0.27%) and to claim a discovery it is 5 sigma (0.000057%). Effects like this go away all the time and can easily be caused by errors. This is not a guarantee that theirs will but, to make claims like this you need solid, statistical evidence and they do not yet have that.
Third: we already know that right handed neutrinos exist because the neutrino has a non-zero mass. Any mass term in the Lagrangian mixes left and right helicity states. Effectively what this means is that if you have a left handed neutrino but chase after it faster than it is moving (which you can do because it has a mass) it will be a right handed neutrino to you. So, if there is anything interesting happening here, it is not a "normal" right handed neutrino.
Pikers (Score:2)
Neutrinos again? Get back to me when they find something the size of a tennis ball:
http://www.scribd.com/doc/36568510/A-Novel-and-Efficient-Synthesis-of-Cadaverine [scribd.com]
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Neutrinos again? Get back to me when they find something the size of a tennis ball:
Wouldn't that simply be a 4.48GHz radio wave? It's wavelength in a vacuum is approximately the size of a tennisball iirc.
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Dude I totally just found it! Tennis balls are the size of tennis balls!
Boo-ya!
What's next? Ooh I know! I'll see if I can find something the size of a bowling ball! Now there's a challenge!
Now let's see... what could be the size of a bowling ball?
Matter / Antimatter (Score:2)
If the universe was primarily made of antimatter instead of matter, would it still be called antimatter?
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Re:Matter / Antimatter (Score:5, Interesting)
I can't speak for people from a hypothetical universe and about what their naming conventions would be, but I can tell you that, given the known laws, the "anti-matter" universe would behave in exactly the same way as ours does.
No, this isn't true (unless time also runs backwards in the anti-matter universe).
Neutral Kaon decay violates CP - You can distinguish K0 decay in our universe from the anti-K0 decay in an antimatter universe.
It is conjectured that CPT symmetry does hold (therefore CP violation implies T violation)
http://en.wikipedia.org/wiki/CP_violation [wikipedia.org]
Tim.
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Well, it's simple: At big bang, the matter went forward in time into our universe, and the antimatter went backward in time into the anti-universe. :-)
Re:Matter / Antimatter (Score:4, Funny)
Well, it's simple: At big bang, the matter went forward in time into our universe, and the antimatter went backward in time into the anti-universe. :-)
And there we have it. Maxwell's Demon, telling us how it all was done!
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Except antimatter is subject to the properties of space and time, it doesn't follow different rules for that. It is simply inverted matter - negative protons and positive electrons, but for every sub-atomic particle.
It's not like anti-matter somehow exists in a different space and time, it exists in our space and time. The Sun in fact spews out a small amount of anti-matter, and that definitely isn't moving backwards in time. We can create anti-matter on earth, and it doesn't go backward in time.
The idea
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May I direct your attention to the three characters at the end of my post? Those letters are:
U+003A COLON
U+002D HYPHEN-MINUS
U+0029 RIGHT PARENTHESIS
You can learn more about the meaning of this character combination at Wikipedia. [wikipedia.org]
Or to make it short:
WHOOSH!
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Except, of course, that there would be more people wearing goatees.
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According to "Star Trek", people from an antimatter universe refer to our antimatter as "antimatter".
Please see the first season episode "The Alternative Factor", for reference.
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Of course not but the question is why there's more of one than the other.
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It is a production error, when God created the Universe. The Universe will be recalled eventually, when enough folks complain, and threaten with lawsuits. The biggest recall, like, ever!
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Not necessarily, but we wouldn't be there to ask. More seriously, who knows what "antimatter" means in their strange antimatter people language.
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It doesn't really matter, the fact is there is more of one than the other, and whatever that other is is not what the universe is made of. If the universe were made of antimatter, all the rules would just be mirrored. Physicists can only guess as to why there is more matter than antimatter (again, names are meaningless, the point is that they are opposites), but it seems to come up consistently in the big particle accelerators.
Logically, they ought to be created in the same proportions, then cancel each o
Yet another neutrino flavor (Score:2)
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Why would they be irritated? Surely that's a Nobel prize which isn't something most people would be irritated to get.
Misleading title (Score:5, Informative)
What has been found is an excess of certain events (namely anti-muon-neutrino to anti-electron-neutrino oscillations), where "excess" is defined relative to the current best-established model. So what this experiment (if correct) shows, is that the current model is not good enough.
From the PRL paper:
The source of the excess remains unexplained, although several hypotheses have been put forward
One of those hypotheses is additional neutrino flavours, but this finding is not evidence for that.
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The finding that the oscillations of anti-neutrinos behave differently than those of neutrinos is very interesting though. It may lead to an explanation of why we see far more matter than antimatter in our universe. This should have been the headline, like here [cbslocal.com].
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The way the story title is written is very bad. Strictly speaking, MiniBooNE has shown an excess of events which do not match Standard Model predictions, which may or may not be explained by the presence of an additional neutrino.
From the abstract, there is "a probability for consistency with the background-only hypothesis of 0.5%", which puts it into the "very suggestive" category rather than the "done deal" category.
Background info:
http://en.wikipedia.org/wiki/Liquid_Scintillator_Neutrino_Detector [wikipedia.org]
http://e [wikipedia.org]
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I would guess that the research is quite solid, the press release is overhyping as usual.
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You are right. The experiment merely published the data from an experimental search for electron antineutrinos appearing in an muon antineutrino beam. There is a 2.7 sigma excess of events in a region of neutrino energies that would be expected from the older LSND experiment, which discovered a 3.8 sigma significant excess in a similar search. The interesting part is that the two experiments see the excess at two very different energy scales. However, the excess is at the same L/E, where L is the distan
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Time asymmetry? (Score:3, Interesting)
The evidence for an asymmetry between matter and anti-matter has been growing for some time now (cosmological observations, recent muon experiments and now this). It used to be said that an antiparticle was a particle travelling backwards in time. So how does these findings affect our understanding of the asymmetry of time?
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Our current fundamental laws don't need to be time symmetrical, they must respect what is called CPT (charge, parity, time reversal). Meaning that the laws of physics of a universe time reserved, with left and right interchanged (ie. spacetime goes (t,x,y,z) ->(-t,-x,-y,-z)) and particles interchanged with antiparticles are exactly the same. Two universes related by CPT are physically indistinguishable.
You can find experiments that portray time reversal violation by looking for CP violation. K^0 decays a
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How does this explanation play with Von Neumann's view that you can't have entropy in a classical universe? I think his point was that there is no way to mathematically describe the "few ordered arrangements [that] are clearly distinguishable" because the classical universe is deterministic. In his quantum description of entropy, though, I believe he argues that waveform collapse changes the information level of the system and produces entropy. This would seem to suggest that the arrow of time is actuall
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First of all the asymmetry between matter and antimatter has been well known for something like 40 years. It was first seen in kaon decays and them more recently in b-meson decays. The issue has been that the size of the asymmetry has never been large enough to explain the universe being made of matter rather than antimatter.
A very fundamental result from quantum field theory is that the combined charge-parity-time symmetry(CPT) must hold or basically no quantum field theory works. Since we know that the qu
Origin of that statement (Score:1)
Symmetry in this case refers to this: If you take a particle or a diagram describing a particle interaction and "flip something", you get something new that is still valid. Take a proton and flip the charge and you get an anti-proton for instance. Because of this symmetry, matter and anti-matter behave in exactly the same way, or so we belive. your particle and your the flipped version decay in the same way for instance.
What physicicst discovered over the last century was that it's not enough to flip the ch
Title and Summary overstates (Score:3, Insightful)
Obvious... (Score:3, Informative)
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I see you've spent a few hours working the Anti-Mass Spectrometer [wikia.com].
Don't reach out too far (Score:2)
"Sterile neutrinos could also possibly help explain the matter asymmetry of the universe,
Isn't it a bit over confidence when assuming and hoping that a neutrino that only interacts via gravity can explain, or was responsible for Baryonic Asymmetry?. None of the *possible* explanations (CP-violation, more matter somewhere than antimatter, antimatter pushed somewhere else etc) I have read anywhere hinted that a hypothetical neutrino, and especially a sterile one, could explain asymmetry. So I am going to take that as a one scientist opinion and hope.
the 4th Kind (Score:2)
Glad they recognized the discrimination, neutrino rights are a big issue these days.
tests confirm... (Score:2, Funny)
http://cheezburger.com/View/4126230016 [cheezburger.com]
Symmetry? (Score:1)
I bet it would be very morphogenetically boring: no structure, no stars, no life. If it was symmetric, it would not have created us to comment on it.
It is asymmetric because we are here, and conversely.
I think I think, therefore I think I am.
strange anomaly? (Score:3, Interesting)
I don't understand why this should be considered strange. Scientists acknowledge that they have only gathered about 1% of the total amount of information available in the universe. Thus the study of the universe is in its infancy and thus new data that contradicts known data shouldn't be considered to be a "strange anomaly". Since when as knowledge gathered from the first 1% of the data in any large study been considered conclusive? Doesn't that missing 99% of the data say any conclusions drawn from the first 1% say that those conclusions should be considered as nothing more than preliminary suppositions?
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Scientists acknowledge that they have only gathered about 1% of the total amount of information available in the universe.
If we keep on collecting information like that, do we not run a risk of creating a black hole or something?
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I'm sorry but this is silly. If you don't know 99% of something, you have no way of even determining if your ignorance is 90% or 99.999999999999999999999%. We have no direct access to quantum foam, or strings, or any way to evaluate the physics down around the Plank Length. There may be a billion billion things we haven't even got a clue about yet, because we have no way of even perceiving or measuring the profoundly small, or anything outside the limits of our light sphere.
Around the end of the 19th centur
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While you disagree with how great a percentage of the knowledge of the universe we know, in essence you agree with my conclusion. That conclusion being that we are ignorant about many things. That should lead to an attitude in which a new discovery should never be referred to as a "strange anomaly". It should be referred to as a new discovery that calls into question our current assumptions. The wisdom of the second way of looking at new discoveries should be self-evident to anyone.
Obligitory John Updike poem (Score:4, Interesting)
Cosmic Gall, by John Updike
NEUTRINOS, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
and painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
and pierce the lover and his lass
From underneath the bed-you call
It wonderful; I call it crass.
And The Flavor Is..... (Score:2)
Neutrino walks into a bar (Score:2)
Neutrino walks into a bar. Bartender says "We don't serve neutrino's here!"
Neutrino says, "Just passing through."
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Idiocist!