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Fermilab Confirms Evidence of 4th Flavor Neutrino

Soulskill posted more than 3 years ago | from the i-hope-it's-grape dept.

Education 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."

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122 comments

Cool (2, Funny)

Haedrian (1676506) | more than 3 years ago | (#34101514)

Will they be ever available in chocolate?

Re:Cool (4, Funny)

GodfatherofSoul (174979) | more than 3 years ago | (#34101624)

Yes, but you're never going to get one to hit your taste buds.

Re:Cool (3, Informative)

Conspiracy_Of_Doves (236787) | more than 3 years ago | (#34101676)

Billions of them pass through your taste buds every second. The problem is getting them to interact with your taste buds.

Re:Cool (1, Insightful)

Anonymous Coward | more than 3 years ago | (#34101790)

I think "Not Interacting" with my taste buds is the same as never hitting my taste buds.

Re:Cool (4, Funny)

AnonymousClown (1788472) | more than 3 years ago | (#34102070)

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!

Re:Cool (0)

Anonymous Coward | more than 3 years ago | (#34102556)

Move over Atkins, here comes the Neutrino Diet!

Won't work. They don't interact with your taste buds, but they do add weight to your hips.

Re:Cool (1)

t1oracle (1908404) | more than 3 years ago | (#34105814)

That's only because you're secretly scarfing down bags of chips, popcorn, and assorted vending machine junk because you didn't eat anything all day and can't figure out why a zero calorie diet doesn't work...

Re:Cool (1)

jayme0227 (1558821) | more than 3 years ago | (#34101782)

Nah, they all taste just like chicken.

Re:Cool (1)

FatdogHaiku (978357) | more than 3 years ago | (#34101896)

As long as they don't say it's "umami" [npr.org]...

Re:Cool (1)

Obfuscant (592200) | more than 3 years ago | (#34104922)

Umami so fat, when she sits around the Large Hadron Collider, she really sits around the Large Hadron Collider.

Raise your hands, everyone who read that as Large Hardon Collider. Ok, raise your free hand.

Re:Cool (0)

Anonymous Coward | more than 3 years ago | (#34102412)

The Moo-on Neutrinos taste like beef.

wel... (1)

t0rb3n (1820822) | more than 3 years ago | (#34101520)

This is sweet!

Re:wel... (1)

Monkeedude1212 (1560403) | more than 3 years ago | (#34101612)

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... (3, Informative)

$RANDOMLUSER (804576) | more than 3 years ago | (#34101880)

CERN != Fermilab

Re:wel... (5, Funny)

Monkeedude1212 (1560403) | more than 3 years ago | (#34101910)

Those guys in white coats all look alike to me.

Re:wel... (1)

bcohen5055 (1428973) | more than 3 years ago | (#34103982)

The only physicists I've ever seen in lab coats were in angles and demons. Real physicists wear suspenders!

Re:wel... (4, Funny)

slick7 (1703596) | more than 3 years ago | (#34104538)

The only physicists I've ever seen in lab coats were in angles and demons.

Angles? Were they so acute they were obtuse?

Re:wel... (1)

lennier (44736) | more than 3 years ago | (#34105646)

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!

Re:wel... (2, Informative)

budgenator (254554) | more than 3 years ago | (#34105388)

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;

* The neutrino beam is produced using 8 GeV protons from the Fermilab booster.
        * The neutrinos are delivered in bursts lasting 1.5 millionths of a second, 5 times per second.
        * The BooNE horn is used to focus the intense, high-energy particle beam and create an intense beam of neutrinos. The horn:
            -operates at 170 kA for 150 millionths of a second;
            -pulses five times per second;
            -must be able to withstand these extreme conditions for 100 million pulses.
        * The BooNE horn has already endured more pulses than any other horn ever!
        * By switching the polarity of the horns, the neutrino beam can be converted into an anti-neutrino beam.
About the BooNE neutrino beam [fnal.gov]

If 8Gev is interesting imagine how exiting 7Tev would be! It's not like many of the neutrinos are going to hit anything between CERN and FermiLab.

Re:wel... (1)

dominious (1077089) | more than 3 years ago | (#34103520)

I kind of understand this after watching a documentary about particle physics and other stuff on Discovery Science (the one with Morgan Freeman). I always thought Discovery is BS, but they did explain this one quite nicely!

Department win (4, Funny)

Verdatum (1257828) | more than 3 years ago | (#34101534)

4th flavor of neutrino; "I hope it's grape", that's just good comedy right there.

Re:Department winur (5, Funny)

migla (1099771) | more than 3 years ago | (#34101630)

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.

Heim Theory? (1)

Felgerkarb (695336) | more than 3 years ago | (#34101554)

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?

Re:Heim Theory? (3, Insightful)

Anonymous Coward | more than 3 years ago | (#34101822)

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.

Re:Heim Theory? (0)

Anonymous Coward | more than 3 years ago | (#34102362)

Comparing theoretical and experimental results in this way (i.e. just referring to the wikipedia table, observing that there are 90+ sigmas of difference and concluding that the theory must be wrong) is incorrect, because the theoretical values are themselves based on the value of some constants (G, h etc.) which are only known to a limited precision. Therefore, one should consider that the theoretical values have an associated uncertainty as well, which is not reported in the wikipedia tables (I wonder why) and which IMO is not unlikely to account for the theory-experiment gap.
The objection about the neutral electron, on the other hand, seems more cogent, and I have no clue on whether and how the supporters of the theory think they can explain that.

Re:Heim Theory? (1)

baryluk (1319237) | more than 3 years ago | (#34103932)

Uncertainities in constants (G, h, c, etc), are included in calculations. They do not explain why experimental values are different. Heim Theory is beautifull, but just wrong. Or there is some error. For example the measurments was actually done based on some incorect theories (for example you do not measure, for example mass directly, you measure energy it given to calorimeter, or how it behaves in magnetic field, and froom this infering mass BASED on other (well established) theory).

This is big problem in interpretation and desigining experiments.

From what I can tell (2, Informative)

sean.peters (568334) | more than 3 years ago | (#34102152)

The actual problem with Heim theory is that it predicted the existence of a neutral equivalent to the electron (per the theory, it should be commonly observed in particle interactions). The fact that such a particle has never been seen is considered a big strike against Heim.

Re:Heim Theory? (5, Informative)

doublegeek (1246564) | more than 3 years ago | (#34102388)

Well, IAAFPP (I Am A Former Particle Physicist, now no longer active in the field), and you have to be careful what you mean by "neutrino". In the Standard Model, neutrinos are partners to the charged leptons: electron, muon, or tau lepton. By "partner to", I mean connected (in a sense) by the weak force, which is the only non-gravitational force that acts on them (being neutral, they are immune to the electromagnetic force, and being leptons, they don't feel the strong force). Neutrinos are also very light, having near-zero mass.

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? (5, Interesting)

maxwell demon (590494) | more than 3 years ago | (#34102800)

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? (5, Informative)

doublegeek (1246564) | more than 3 years ago | (#34103594)

Your reasoning looks pretty sound to me; I don't think there is a fundamental reason to assume that right-handed neutrinos don't exist. I think the main reason people make that assumption is that there is no experimental evidence for it. It appears that the weak force only acts on left-handed particles

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.

Re:Heim Theory? (1)

maxwell demon (590494) | more than 3 years ago | (#34104006)

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.

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 into a right-handed neutrino and something else?

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).

Are you sure? 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: Either the electron interacts, or it doesn't.

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.

Well, the point is not that it's needed, the point is that to me it seems unnatural to assume it doesn't exist. Therefore given that AFAIK particle physicists generally do so, I expect there to be good reasons for that which I don't know.

Re:Heim Theory? (4, Informative)

doublegeek (1246564) | more than 3 years ago | (#34105306)

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.

Re:Heim Theory? (0)

Anonymous Coward | more than 3 years ago | (#34105470)

are you trying to make my head explode?

Re:Heim Theory? (1, Informative)

Anonymous Coward | more than 3 years ago | (#34105802)

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 particle interacts in some reference frame but not in others...

By the way, gravity can actually create particles. In expanding universes like a deSitter space, the expansion creates particles in pairs. I must clarify I have verified this calculation only for scalar fields (I cannot confirm it right now for spin 1/2 particles). For further reading at this respect check Wald, QFT in Curved Spacetime and Black Hole Thermodynamics.

Answers (4, Informative)

Roger W Moore (538166) | more than 3 years ago | (#34104564)

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.

Confused (-1, Troll)

Anonymous Coward | more than 3 years ago | (#34101602)

1st flavor - white
2nd flavor - nigger
3rd flaver - mixed, gray baby, mulatto, half-n-half, half-breed, oreo, etc.
4th flavor - ?

Pikers (1)

paiute (550198) | more than 3 years ago | (#34101646)

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]

Re:Pikers (2, Informative)

IndustrialComplex (975015) | more than 3 years ago | (#34101792)

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.

Re:Pikers (2, Funny)

Bigjeff5 (1143585) | more than 3 years ago | (#34104012)

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 (1)

Applekid (993327) | more than 3 years ago | (#34101904)

If the universe was primarily made of antimatter instead of matter, would it still be called antimatter?

Re:Matter / Antimatter (1)

somegeekynick (1011759) | more than 3 years ago | (#34101946)

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.

Re:Matter / Antimatter (5, Interesting)

locofungus (179280) | more than 3 years ago | (#34102158)

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.

Re:Matter / Antimatter (1)

maxwell demon (590494) | more than 3 years ago | (#34102882)

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 (3, Funny)

jschen (1249578) | more than 3 years ago | (#34103796)

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!

Re:Matter / Antimatter (2, Informative)

Bigjeff5 (1143585) | more than 3 years ago | (#34104154)

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, really, is silly.

The only thing really special about the matter-anti-matter relationship is that for some reason more matter gets created in these massive collisions of energy than anti-matter. If this were not so the universe as we know it would not exist.

Re:Matter / Antimatter (3, Funny)

maxwell demon (590494) | more than 3 years ago | (#34104448)

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!

Re:Matter / Antimatter (1, Funny)

Anonymous Coward | more than 3 years ago | (#34102316)

Except, of course, that there would be more people wearing goatees.

Re:Matter / Antimatter (1)

sconeu (64226) | more than 3 years ago | (#34103868)

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.

Re:Matter / Antimatter (2, Funny)

Barrinmw (1791848) | more than 3 years ago | (#34101976)

We would know because everything would be spinning in the opposite direction. ;-)

Re:Matter / Antimatter (1)

KDR_11k (778916) | more than 3 years ago | (#34101982)

Of course not but the question is why there's more of one than the other.

Re:Matter / Antimatter (1)

PolygamousRanchKid (1290638) | more than 3 years ago | (#34102284)

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!

Re:Matter / Antimatter (1)

Even on Slashdot FOE (1870208) | more than 3 years ago | (#34101994)

Not necessarily, but we wouldn't be there to ask. More seriously, who knows what "antimatter" means in their strange antimatter people language.

Re:Matter / Antimatter (2, Informative)

Bigjeff5 (1143585) | more than 3 years ago | (#34104072)

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 other out completely. They aren't though, and because of that we exist. Why aren't they balanced? That's one of the big questions that needs an answer.

Yet another neutrino flavor (1)

$RANDOMLUSER (804576) | more than 3 years ago | (#34101956)

The Standard Model guys are going to be so irritated when they finally figure out that all these "flavors" are all manifestations of the same thing; what they're doing now is analogous to calling electrons in different shells different particles.

Re:Yet another neutrino flavor (1)

nedlohs (1335013) | more than 3 years ago | (#34102130)

Why would they be irritated? Surely that's a Nobel prize which isn't something most people would be irritated to get.

Misleading title (5, Informative)

Baron Eekman (713784) | more than 3 years ago | (#34102050)

There is no "Evidence of 4th Flavor Neutrino" here.

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.

Re:Misleading title (3, Informative)

Anonymous Coward | more than 3 years ago | (#34102560)

Replying to myself as AC.

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].

Re:Misleading title (2, Insightful)

mako1138 (837520) | more than 3 years ago | (#34102916)

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://en.wikipedia.org/wiki/MiniBooNE [wikipedia.org]

Re:Misleading title (3, Interesting)

Baron Eekman (713784) | more than 3 years ago | (#34102986)

The finding that the oscillations of anti-neutrinos behave differently than those of neutrinos is very interesting though, even when "very suggestive". It may lead to an explanation of why we see far more matter than antimatter in our universe. That should have been the headline, like here [cbslocal.com].

I would guess that the research is quite solid, the press release is overhyping as usual.

Re:Misleading title (1, Informative)

Anonymous Coward | more than 3 years ago | (#34103448)

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 distance the beam has covered and E is the energy region of the excess. This is partially by construction as the MiniBooNE experiment was built to cover the same L/E range. However, an L/E invariant excess is what would result from a model with oscillations to a 4th sterile neutrino. Simple extensions with a single sterile neutrino would produce results incompatible with other neutrino experiments, so we know it really has to be something more complicated...perhaps multiple sterile neutrinos. This is also made more interesting/confusing by the fact that the MiniBooNE experiment also saw a 3.0 sigma excess that could be interpreted as muon neutrinos oscillating to electron neutrinos, but at a lower neutrino energy. If neutrinos and antineutrinos were shown conclusively to behave differently then it would be one of the most significant findings of the last century.

This is all suggestive, but in the field of particle physics there are many distributions examined for consistency with the Standard Model. If there are 1000 distributions examined then there should be 5 results with this level of discrepancy. That is why a more significant result is needed before any serious claims of new physics are made.

Neutrinos - The fresh maker. (0)

Anonymous Coward | more than 3 years ago | (#34102072)

sorry

Time asymmetry? (2, Interesting)

hawkfish (8978) | more than 3 years ago | (#34102210)

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?

Re:Time asymmetry? (1, Informative)

Anonymous Coward | more than 3 years ago | (#34102548)

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 are an example.

Re:Time asymmetry? (1, Informative)

Anonymous Coward | more than 3 years ago | (#34102674)

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 quantum field theories that make up the Standard Model work very well, we're pretty sure CPT holds. Therefore any matter-antimatter asymmetry implies a corresponding time asymmetry.

However, these asymmetries are unlikely to explain the macroscopic arrow of time (why the future is different from the past). The answer to that question most likely comes from statistical mechanics.

Title and Summary overstates (2, Insightful)

forand (530402) | more than 3 years ago | (#34102230)

The scientific article does a reasonable job of making it clear that this result has a 0.5% probability of being produced entirely by background assuming that the systematics of the result are not playing evil games with you. While this result is interesting and it may, strictly speaking, "confirm evidence of 4th neutrino flavor" it only does so by being consistent with both a background fluctuation and some theories developed to describe a discrepancy similar to that seen in the data. It most certainly does not eliminate the standard model nor does it pick out any particular theory.

Obvious... (2, Informative)

flyingfsck (986395) | more than 3 years ago | (#34102262)

The MiniBooNE experiment at Fermilab reports results from a search for e oscillations, using a data sample corresponding to 5.66×1020 protons on target. An excess of 20.9±14.0 events is observed in the energy range 475EQE1250MeV, which, when constrained by the observed events, has a probability for consistency with the background-only hypothesis of 0.5%. On the other hand, fitting for e oscillations, the best-fit point has a 2 probability of 8.7%. The data are consistent with e oscillations in the 0.1 to 1.0eV2 m2 range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory. Yeah, well, no fine...

Re:Obvious... (0)

Anonymous Coward | more than 3 years ago | (#34106096)

You might note that this is the abstract from the summary-linked PRL paper, minus some Greek symbols.

Don't reach out too far (2)

sosaited (1925622) | more than 3 years ago | (#34102332)

"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 (1)

digitaldc (879047) | more than 3 years ago | (#34102360)

"Physicists at the lab now believe that antimatter particles behave pretty much in the same way as their regular matter counterparts do."

Glad they recognized the discrimination, neutrino rights are a big issue these days.

Neutrino kitteh says (-1)

Anonymous Coward | more than 3 years ago | (#34103136)

I haz a flavour

Symmetry? (1)

migloo (671559) | more than 3 years ago | (#34103468)

Let us fantasize about how a matter-symmetric universe would evolve.
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? (2, Interesting)

ffreeloader (1105115) | more than 3 years ago | (#34103870)

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?

Re:strange anomaly? (2, Funny)

ardle (523599) | more than 3 years ago | (#34104198)

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?

Ancient Chinese Secret (1)

the_hellspawn (908071) | more than 3 years ago | (#34104286)

This one is obvious! There are only four elements; Earth, wind, fire, and water, so there are only four neutrino. That is it. There are no anti anything. From one side your anti and from the other your not.

Obligitory John Updike poem (4, Interesting)

Subm (79417) | more than 3 years ago | (#34104486)

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.

Baskin Robbins just built a new supercollider.... (0)

Anonymous Coward | more than 3 years ago | (#34105572)

And it produces 31 different flavors of neutrinos. Physicists also receive one free particle of anti-matter on their birthdays.

And The Flavor Is..... (1)

IHC Navistar (967161) | more than 3 years ago | (#34106022)

According to Professor Hubert G. Farnsworth, the neutrino tastes like GrapeAid. The next question to answer is..... WILL IT BLEND??
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