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

Posted by BeauHD on from the surprise-findings dept.

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.

12 of 94 comments (clear)

  1. Straight from wikipedia by Anonymous Coward · · Score: 5, Informative

    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.

    1. Re:Straight from wikipedia by Narcocide · · Score: 2

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

    2. Re:Straight from wikipedia by slack_justyb · · Score: 3, Interesting

      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. 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.

    3. Re:Straight from wikipedia by Baloroth · · Score: 5, Interesting

      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.

      --
      "None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
    4. Re: Straight from wikipedia by Joce640k · · Score: 3, Funny

      She's not massless, though.

      --
      No sig today...
    5. Re:Straight from wikipedia by Pfhorrest · · Score: 2

      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 the question of what is confining what energy to cause that; why aren't all the fundamental particles massless? The answer to that is the Higgs field: all of the would-have-been-massless fundamental particles interact constantly with the Higgs field, confining some of what would have been their kinetic energy, giving them mass (and making them move slower than light in the process).

      That's what prompted my initial question. If these sterile neutrinos don't interact with anything, then how can they be massive, since all mass arises from interactions? Someone elsewhere in the comments has said that the origin of neutrino mass is a mystery, as according to the Standard Model they should be massless, and these sterile neutrinos are part of one proposed explanation for that mystery, but I don't quite understand it yet.

      --
      -Forrest Cameranesi, Geek of all Trades
      "I am Sam. Sam I am. I do not like trolls, flames, or spam."
  2. Boffins in America by freeze128 · · Score: 5, Funny

    "Many boffins died to bring us this information."

  3. Was it born that way? by hyades1 · · Score: 5, Funny

    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?

    --
    I've calculated my velocity with such exquisite precision that I have no idea where I am.
  4. Stop linking to tabloids by locater16 · · Score: 5, Informative

    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/...

  5. Re:"May have" by Required+Snark · · Score: 2

    The Sun emits lots of neutrinos.

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    Why is Snark Required?
  6. Bad fit and contradicts other experiments by johanw · · Score: 2

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

  7. Re:Tau Neutrino? by habig · · Score: 2
    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 MINOS and IceCube. What is it then? We'd love to know, but odds are it's not a sterile neutrino.