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Science

Scientists May Have Discovered a New Fundamental Particle: Sterile Neutrino (theregister.co.uk) 94

Artem Tashkinov writes: It needs more sigmas, but Fermilab boffins in America are carefully speculating that they may have seen evidence of a new fundamental particle: the sterile neutrino. The suggestion follows tests conducted by the MiniBooNE (Mini Booster Neutrino Experiment) instrument, located near Chicago. Its mission is to detect neutrino mass through their oscillations. In the Standard Model of physics, neutrinos, like all particles, are initially assumed to be massless, but some observations, like neutrino oscillation, suggest there's mass there. The experiment that possibly detected sterile neutrinos collected 15 years of data from its commissioning in 2002, and the results have only now reached pre-press outlet arXiv.

Over 15 years, MiniBooNE detected a few hundred more electron neutrinos than were predicted in Standard Model theory. The extra particles suggests there is a fourth, heavier flavor. The findings bring the MiniBooNE team tantalizingly close to a "result" -- it's a 4.8 sigma result, when "discovery" demands 5 sigma.

Scientists May Have Discovered a New Fundamental Particle: Sterile Neutrino

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  • by Anonymous Coward on Tuesday June 05, 2018 @11:46PM (#56734976)

    Sterile neutrinos (or inert neutrinos) are particles that interact only via gravity and do not interact via any of the fundamental interactions of the Standard Model.

    One little sentence in the summary would have made it SO much more worth reading.

    • If it doesn't interact with any of the other fundamental forces, from where does its mass come? Or does Higgs interaction not count?

      • Maybe they just don't have mass in this dimension, but gravity itself spills through to multiple dimensions.

      • by slack_justyb ( 862874 ) on Wednesday June 06, 2018 @12:36AM (#56735058)

        from where does its mass come

        Well ask yourself this, where does the majority of mass of a proton come from? A proton is an imbalance in a sea of gluons of exactly two up quarks and one down quarks. That is 2 * 2.3 MeV/c**2 + 4.8 MeV/c**2 = 9.4 MeV/c**2 but the Proton is 938 and some change MeV/c**2, that's a roughly 930 MeV/c**2 difference. Where does the extra energy come from?

        Potential energy, thermal energy, and so on all contribute to the mass of an object. Indeed, even particles that interact via the Higgs mechanism do so via a potential difference. The leading idea for potential energy difference in neutrinos is via the seesaw mechanism. [wikipedia.org] but the point is that differences between any two things creates a potential and the energy of that potential contributes to mass and in the case of the proton, is pretty much the majority of the mass.

        • I understand about 20% of what you said. It just reminds me everything stays super complicated down to the level is a bunch of different subatomic particles that we don't understand at all. All this complex system Ina single atom. Then 100 trillion atoms in a single cell of my body, making up complex structures such as ion pumps to move various things in and out of the cell, self-replication machinery, thousands of structures. With all of these systems within systems within systems too complex for physici

          • by fisted ( 2295862 )

            Amazing that all of it, all of these systems and structures, quintillions of individual parts just happened to randomly come together into perfectly working, self-sufficient systems without any of it ever being designed.

            Maybe far simpler systems came together by chance, and evolved given an enourmous amount of time? I know, I know. Unconvential thoughts and all.

          • by mikael ( 484 )

            Like genetic algorithms, you start with something simple, then apply operations like duplicate, mutate best performers, cull worst performers, and repeat. There are some genetic frameworks; the groups of three amino acids (codons) that encode basic proteins. It's more of a stack based geometry language in that it allows to roll back by one amino acid, remove it and begin a new sequence. There's also END codons. From that you can build enzymes, RNA, DNA. The cell machinery allows for routing of proteins with

          • It's not really THAT amazing, it kind of falls out of the math (so to speak) when you factor in evolutionary pressures. That's the thing about "designers", the universe doesn't need one so it's talk better left for the seminary than the laboratory

          • I felt the same reading the OP so I dug up a bit on what it all means and found it quite interesting. We asked where the mass comes from, but we didn't say what we meant by mass. In classical physics, mass just "is" -- it's a fundamental property of matter, that gives things weight in gravity. But in quantum mechanics, mass is a property derived from the energy of a fundamental zero-volume "particle" like photon or electron, or a system like the helium nucleus (which we see it as two neutrons plus two proto

        • by Bengie ( 1121981 )
          Most of the mass of a proton comes from the attractive energy among the quarks, not from their rest mass.
        • Well ask yourself this, where does the majority of mass of a proton come from?

          I am pretty sure that if you measure the strength of the "gravity" field around the proton, it would correspond nicely to the mass field of the proton.

          The existence of matter causes the existence of space-time. The reverse is also true, but it is difficult to talk about this stuff from the POV of the standard model.

      • by Baloroth ( 2370816 ) on Wednesday June 06, 2018 @01:10AM (#56735130)

        Higgs interactions do not count, as the Higgs is not a fundamental force. The sterile neutrino is actually a solution to the problem of the neutrino mass: neutrinos are massless in the Standard Model, but not in reality, so we know there must be some mechanism to produce their observed mass. A coupling of the neutrino to its sterile counterpart (through the Higgs) could give it mass in the same way as all the other fermions, but that requires sterile neutrinos (or very very heavy non-sterile neutrinos), which are heavily dis-favored by theoreticians. The alternative, the Majorana mechanism, would make the neutrino and anti-neutrino the same particle and give them mass by coupling them together. This measurement, if true (it's possible there's unknown systematics) would probably prove the sterile neutrino theory correct, though it's possible there is another explanation. Neutrinos are tricky beasts.

        • Thank you for that detailed explanation, but can you elaborate further on how the Higgs interaction is not fundamental? What is it then?

        • Higgs interactions do not count, as the Higgs is not a fundamental force.

          Higgs interactions do count if you are counting interactions. It is wrong to say that they only interact via gravity if they also interact via the Higgs. It might not be a force but it is an interaction. For example, if Dark Matter interacts via the Higgs we would not say that its only interaction is via gravity.

      • Higg is a field, not a fundamental force. I know that sounds wanky, but there's only 4 fundamental forces and several fields.
        • So far as I understand it, every fundamental force (except possibly gravity which is yet unaccounted for in quantum field theories) is mediated by some kind of particle which is just an excitation of that field, e.g. the electromagnetic force corresponds to the electromagnetic field, which is to say the photon field as photons are just excitations of the electromagnetic field, and interaction with photons constitutes the electromagnetic force, as every electromagnetic interaction is mediated by an exchange

          • AFAIK, the Higgs Field imparts mass or gravity.. not sure which. Somewhere in there is the idea of the graviton as the particle that comes from the higgs field.
            • The Higgs field is unrelated to gravity as a force. Gravity acts on energy regardless of its form. Mass is what happens when energy gets confined. Most of the mass of normal matter can be accounted for by the binding energies confined in composite particles: the forces that hold atoms together into molecules, electrons and nuclei together into atoms, nucleons together into nuclei, and quarks together into nucleons. But the fundamental particles like those quarks and electrons also have mass, which raises th

              • by Bengie ( 1121981 )

                If these sterile neutrinos don't interact with anything, then how can they be massive

                Depends on what the definition of "anything" is. It's a very non-scientific term.

      • You know, that's one area of particle physics that's always troubled me. For the longest time we thought that mass gave rise to gravity. Then it looked like it might have been the other way around. Now it looks like a particles gravity and mass are effectively independent. (which is just weird as hell)
        • Gravity acts upon energy (or you could phrase it as energy distorts spacetime, which is the same thing). Mass is just rest energy, confined energy that's not free to be kinetic energy. (The Higgs field explains what is confining energy in the otherwise free, unconfined fundamental particles that nevertheless have mass for no other apparent reason). Where does it look like gravity and mass are at all independent?

    • by mikael ( 484 )

      Does that make them gravitons?

    • Does that make them a candidate for Dark Matter?

      • Does that make them a candidate for Dark Matter?

        Yes. They are one possible part of the possible dark matter, but it is doubted that if they do exist, they would be all of it. ( Maybe not from TFA, but from a similar FA.)

    • Considering how rarely existing neutrinos interact with common matter, I'm not surprised that there is another flavour that doesn't interact *at all* or, more pedantically, doesn't interact with matter at all to the limits of our ability to measure. After all, your typical neutrino can go through a light year thick piece of lead without interacting. Existing detection set ups would have billions or trillions of neutrinos pass through them undetected for every neutrino that does manage to interact with an at
  • by freeze128 ( 544774 ) on Wednesday June 06, 2018 @01:05AM (#56735116)
    "Many boffins died to bring us this information."
    • by mjwx ( 966435 )

      "Many boffins died to bring us this information."

      Yes, but that's because over this side of the pond we administrators pit them against each other thunderdome style for our own amusement, two scientists enter, one scientist leaves. The actual research is quite safe.

  • by hyades1 ( 1149581 ) <hyades1@hotmail.com> on Wednesday June 06, 2018 @02:39AM (#56735290)

    One has to ask: was this neutrino born sterile, or was it "fixed" because it lepton some poor physicist and left a meson his leg?

    • by mjwx ( 966435 )

      One has to ask: was this neutrino born sterile, or was it "fixed" because it lepton some poor physicist and left a meson his leg?

      Well you've got the sterile neutrino that only reacts with gravity, not the other interactions in the standard model, then you've got the Incel neutrino which "involuntarily chooses" not to have any interactions with a model, standard or otherwise and spends most of its time slagging off the standard model on Neutrinos Going Their Own Way forums.

    • We may have a new movement: the insteriles.
  • by locater16 ( 2326718 ) on Wednesday June 06, 2018 @04:45AM (#56735496)
    Seriously, wtf, how does this get on here?

    Because this is shit science reporting to nth degree. What scientists have found is a more controllable source of neutrinos, ones that result from kaon decay, that can eliminate the variability that prevents neutrino experiments from being conclusive. That this was in any way connected with sterile neutrinos is because it was an accidental discovery from an apparently inconclusive experiment trying to find sterile neutrinos, but the discovery itself is no indication of whether sterile neutrinos exist or not.

    There, the truth, now please never ever link to another shit site that does this again: https://smbc-comics.com/comic/... [smbc-comics.com]
    • Did you actually look at the article and the abstract or are you just copying this from somewhere for points? The abstract is talking about exactly what the article is talking about. There is no mention of "scientists finding a more controllable source of neutrinos" as far as I can tell that's just something you pulled out of your ass, unless you are talking about the 15-year-old MiniB00NE itself.
  • Is this The Sun or /. ?
  • Is this /. or The Register?

    (yes of course the link is to the Register, who over-uses the word Boffins like a bartender does ambien)

  • The paper makes no mention of the tau neutrino which, at these energies, would appear "sterile" because there is not enough energy to produce a tau. Indeed the paper keeps using what it calls the "two neutrino" model when we know there are three neutrinos which oscillate.

    Some justification as to why the tau neutrino is excluded would be helpful as would a three-neutrino analysis even if the mixing angles mean that the tau component is negligible. I suspect there are some good justifications for this appr
    • by habig ( 12787 )
      At the baseline and energy where Miniboone operates, numu have not had time to oscillate to nutau. At 10x the energy and 100x the baseline (eg, Nova, MINOS) they do, and this is measured well.

      So, that access to the 3rd neutrino state isn't there for this experiment, which is why they're talking about the 2 states in play.

      That said: the simple 3+1 neutrino model they propose, which would fit the Miniboone results on its own, is pretty solidly ruled out by a number of other experiments, most recently MIN

  • As some posters in this thread on Physics Forums pointed out in http://physicsforums.com/threa... [physicsforums.com] , this result is a bad fit of the data and contradicts other experiments like the Planck satellite results.

  • Experimental Particle Phycist Tomasso Dorirgo http://www.science20.com/tomma... [science20.com] doesn't rate the 4.8 sigma excess satistics as valid, thinks the systematic uncertainitys are much bigger.

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