Become a fan of Slashdot on Facebook

 



Forgot your password?
typodupeerror
Science

Neutrino Experiment Restores Standard Model Symmetry 83

Posted by kdawson
from the eightfold-way dept.
perturbed1 writes "A Fermilab press release announced that MiniBooNE's latest results have salvaged the Standard Model of particle physics. The experiment ruled out the simple neutrino oscillation interpretation of the 1990s LSND experiment. Neutrinos have a tiny amount of mass, required by their oscillations, as observed in solar, atmospheric, and reactor neutrino experiments. Combining this mass with the LSND experiment's results required the presence of a fourth but 'sterile' neutrino, breaking the 3-fold symmetry of particle families in the standard model." Nice to see some good news out of Fermilab after the CERN debacle.
This discussion has been archived. No new comments can be posted.

Neutrino Experiment Restores Standard Model Symmetry

Comments Filter:
  • Good news (Score:4, Funny)

    by michaelmalak (91262) <michael@michaelmalak.com> on Thursday April 12, 2007 @08:20AM (#18701247) Homepage
    Can Fermilab next restore Newton's model? That speed of light thing is hampering processor speed and space travel.
    • by QuantumG (50515)
      What is inertia, where does it come from? How do you explain it with particle physics? Start answering those questions and the speed of light stops being a barrier.
      • Re: (Score:3, Funny)

        What is inertia, where does it come from?

        Mine comes from nearly a decade in a sedentary job, and way too much cola over same time period. What does that have to do with the speed of light, though?
        • by metlin (258108) *
          Mine comes from nearly a decade in a sedentary job, and way too much cola over same time period. What does that have to do with the speed of light, though?

          It's all that mass that you've gained over the years that's slowing light down. ;-)
      • Re: (Score:2, Informative)

        by Dr_Mic (975409)
        Actually, things without inertia (photons, for example) automatically go the speed of light. As a particle's energy increases (beyond rest mass energy), it becomes more "photon like" in that it asymptotically approaches the speed of light. So removing inertia will eliminate that inconvenient acceleration, but leave in place the ultimate speed limit.
        • by QuantumG (50515)
          The question is: why? How do you explain this observed phenomona that things without inertia go the speed of light? Where does inertia come from? Einstein proposed a possible explaination [wikipedia.org] which he attributed to Mach (and Mach refused) but other than that little has been said about it since Newton (who say it as an intrinsic property). When we understand inertia, then we'll understand why the speed of light is a barrier and can think of practical ways future societies might get around it.
          • by Dr_Mic (975409)
            no no no I was trying to point out that inertia and the light speed "barrier" are not one in the same. Inertia clues us in how things with mass cannot be made to go to the speed of light (it would take infinite energy/work). However, the very structure of space time prohibits FTL motion or even communication (unless you are willing to sacrifice causality: cause always precedes effect). As soon as you have FTL motion/communication, you have the equivalence of time travel (backwards in time)/ability to se
            • by QuantumG (50515)
              causality and locality are already dead aint they?

              anyway.. I'm quite happy to say we don't know enough to say one way or another whether or not the speed of light is a real barrier to an advanced civilization.

              Exotic matter is believed to exist. Techniques for using energy to make the gravitational effects of exotic matter are believed to be possible. So wormholes and warp drives are not out of the question, theoretically.. but it's still an insanely difficult engineering proposition, even if we knew how t
              • by Dr_Mic (975409)

                causality and locality are already dead aint they?

                Really? I missed the obituray. Got a journal citation? (something other than Cramer's interpretational abuse of "retarded wave functions" I hope.)

                anyway.. I'm quite happy to say we don't know enough to say one way or another whether or not the speed of light is a real barrier to an advanced civilization.

                Are you saying that there is significant doubt about relativity? Relativity is solid; "star trek" type interstellar voyages are beyond unlikely. You seem implying a doubt in relativity that does not exist within the physics community. There is I suppose in some technical sense we don't know for sure, but this is not like a late 1800's claim that man will ne

      • by joto (134244)

        Inertia is a fashion garment worn by ladies in the 1920s, but mostly forgotten today. Originally, it was spelled inner-tiara, but with time the word contracted into its present form: inertia. It originated in Paris, as every fashion-garment from the 1920s did. Physicists are still stumbling with how to explain fashion garments. Using the standard model, this task has proved extremely difficult. Most physicists agree that in order to explain fashion garments fully, a new theory is needed. Often this theory i

    • by UbuntuDupe (970646) *
      Space travel I can understand, but don't you dare try to pin processor speed limits on the speed of light. If you want a fast computer, you can do it just fine under the present model. Simply compress 1 kg of matter into a black hole of radius 1.485e-27 m. In the 1e-19 seconds before evaportion due to Hawking radiation, you can perform 5e50 operations per second. It only gets you 1e32 total operations on 1e16 total bits, but it's fast. If you can't do that, you only have yourself to blame.

      (Yeah, yeah, b
  • NOT good news! (Score:5, Insightful)

    by YA_Python_dev (885173) on Thursday April 12, 2007 @08:36AM (#18701449) Journal

    This isn't exactly what most scientist would consider "good news". We already know that both the standard model and the general relativity are wrong or at least incomplete, but they continue to pass every experiment, including this one...

    The reason they keep trying is because they hope to finally find something different from what those theories predict: this will probably open a very exciting period of progress for our understanding of the universe.

    More infos: start from unsolved problems in physics [wikipedia.org] and click links.

    • Re: (Score:2, Interesting)

      by Boghog (910236)
      We already know that both the standard model and the general relativity are wrong or at least incomplete.

      Not trolling, but the above statement reminds me of the following quotation:
      All models are wrong, some are useful.
      http://en.wikiquote.org/wiki/George_E._P._Box/ [wikiquote.org]
      • Re: (Score:3, Insightful)

        by syntaxglitch (889367)

        Not trolling, but the above statement reminds me of the following quotation:
        All models are wrong, some are useful.
        http://en.wikiquote.org/wiki/George_E._P._Box/ [wikiquote.org]

        Indeed, that's exactly the point. The Standard Model is quite useful, but also "wrong" and (even worse) wrong in a rather boring sort of way. The problem is that to find a new model that's slightly less wrong, or at least a more interesting kind of wrong, we need to find ways in which the Standard Model is less useful.

        Thus, yet more confirmation of its utility boils down to "that's great, but now what?"

    • I consider it bad news from the viewpoint that unexpected results are much more exciting to everyone involved. If you have dedicated your life to the standard model then you might not be happy about it but it would certainly wake you up.
    • Re:NOT good news! (Score:5, Insightful)

      by mstahl (701501) <`marrrrrk' `at' `gmail.com'> on Thursday April 12, 2007 @09:23AM (#18701953) Homepage Journal

      We already know that both the standard model and the general relativity are wrong or at least incomplete, but they continue to pass every experiment

      (Emphasis mine). If that's true, then how do we "already know" that the standard model and GR are broken? The way that we tell if a theory is broken is by experimentation.

      I know you're probably talking about the whole dark matter/energy debate, but neither of those means general relativity is broken, necessarily. They could be indications that general relativity needs some elaboration or, most likely, there exists circumstances where we can experimentally show it to be broken (i.e., not just by observing cosmology from afar but actually in a lab). If we haven't found those circumstances yet, experimentation is how we keep looking. The good news of this article is that one experiment's results, which if accepted would have required major rewriting of theories, were not reproducible. We're one step closer to explaining them.

      • by pavon (30274) on Thursday April 12, 2007 @10:05AM (#18702307)
        If theory A predicts one thing and theory B predicts another then they can't both be right. You don't need an experiment to tell you that, logic is sufficient. Unfortunately, the situations in which they disagree are ones that we cannot easily reproduce or observe in nature. Until we do find such evidence we won't know exactly how they are wrong, or the correct way the reconcile them, but it doesn't preclude us from knowing that they are incomplete.

        but neither of those means general relativity is broken, necessarily. They could be indications that general relativity needs some elaboration
        Now you're just playing semantic games. Yeah, few established theories are ever shown to be completely wrong, just simplifications that only work in certain circumstances. As far as science is concerned "broken" and incomplete mean the same thing.
        • by AndersOSU (873247)

          If theory A predicts one thing and theory B predicts another then they can't both be right. You don't need an experiment to tell you that, logic is sufficient.
          Are you sure? [wikipedia.org]
          • by joto (134244)
            By "logic", one usually means just that. That "logic" can also mean "a family of mathematical formalisms for describing systems involving truth-values or at least stuff that has some resemblance to truth-values" does not mean that quantum logic should be your first guess when you hear the word logic. Just as modulo-7 arithmetic should not be your first guess whenever you see a plus-sign.
        • As far as science is concerned "broken" and incomplete mean the same thing.
          Then all science is "broken," since it will always be incomplete.
          As an engineer something isn't "broken" until it stops working. That's why we still use Newtonian physics for solving simple problems, the theory may be fundamentally "broken," but for our interests it works well enough.
      • It's a problem of scale / energy levels. We know GR works for very big things with high gravity. We know the Standard Model works for small things with low gravity (but high in the other 3 forces). The problem is, they don't agree for things that are small and high gravity (e.g., black holes). Since thw two theories give different results, at least one of them has to be "wrong." The problem is finding a way of testing in these somewhat extreme circumstances (making a black hole is not as easy as you mi
        • by Dan Ost (415913)
          (making a black hole is not as easy as you might think)

          Legal departments do, however, offer a close approximation.
      • Re: (Score:2, Informative)

        by Phleg (523632)
        The problem is that as stated, the Standard Model and General Relativity are mutually exclusive. As they stand, both imply the invalidity of the other. But General Relativity is great for analyzing big things, and the standard model for extremely tiny things. Both make predictions with surprising accuracy. But as stated, they're incompatible.
        • The problem is that as stated, the Standard Model and General Relativity are mutually exclusive. As they stand, both imply the invalidity of the other. But General Relativity is great for analyzing big things, and the standard model for extremely tiny things. Both make predictions with surprising accuracy. But as stated, they're incompatible.
          I'm happy then to inform you that there is the black hole radiation.
      • by Parlyne (884090)
        We already know that the Standard Model and GR are "broken" because we know of a major fundamental shortcoming of each. In the case of the standard model, the major dealbreaker is quite simply that it doesn't include any kind of description of gravity. Also, it has no way of accounting for the fact that neutrinos have mass. GR, on the other hand, we know to be broken because it isn't in any way quantum mechanical, which the universe is. Given that we know that our best models are not only broken, but ir
      • Re: (Score:3, Informative)

        by shma (863063)
        The way that we tell if a theory is broken is by experimentation.

        That is not entirely true. A theory which also gives infinite answers to certain questions, or answers which contract results from other (accepted) theories must be broken as well. For the standard model, however, we DO have results that conflict with observation. For example, there is the so called cosmological constant problem [wikipedia.org]. For GR, I assume the poster was referring to the problem of trying to integrate GR with quantum field theory. M
        • The way that we tell if a theory is broken is by experimentation.
          That is not entirely true. A theory which also gives infinite answers to certain questions, or answers which contract results from other (accepted) theories must be broken as well.
          That is not entirely true. Take for example the quantum electrodynamics: it's broken beyond repair and still very accurate in many experiments, but not all of them. Physics is also an experimental science.
      • As G.R. and Q.M. are contradictory, there must be a more complete theory (the "Grand Unified Theory") which simplifies to G.R. in the limit of large sizes and to Q.M. in the limit of small gravitational potentials.

        We already see many other such simplifications in physics: Quantum mechanics simplifes to Newtonian mechanics in the limit of large sizes. General relativity simplifies to special relativity in the limit of no gravity. General relativity simplifies to Newtonian gravity in the limit of low velociti
      • If that's true, then how do we "already know" that the standard model and GR are broken?
        How do we know the Standard Model and GR are broken? Two words: quantum gravity.
    • by hosecoat (877680)
      we fear change
    • by gertam (1019200)

      >The reason they keep trying is because they hope to finally find something different from what those theories predict: this will probably open a very exciting period of progress for our understanding of the universe.

      I disagree. This is good news because finding the truth is good news. The purpose of Science is to find the truth (or as close an approximation as possible), not to find more Science to do. Whatever the reality of the Universe, discovery of that is what is important. If we find the Higgs bos
    • Re: (Score:1, Troll)

      by Jugalator (259273)
      The problem with scientists is that they need to adjust to the fact that Albert Einstein was an incarnation of God.
    • I say it's bad news because the standard model is freaking boring.

      I still hope to see real interstellar travel before I die (not sticking a bunch of corpsicles in a solar sail powered coffin and sending them out into deep space for a million years), and considering I'm 30 now, I hardly find that likely if the standard model turns out to be right.

      Honestly, for those of us who want to see the human race EVER reach the stars (before we succeed in creating another Dark Ages or get smashed by a meteor), the wo
      • by joto (134244)
        Good luck in that. I try to have less loftier goals, such as saving humanity from war or famine, or something like that.
        • Way to look at the short term goal. Save the human race now so they can die later.

          Seriously, perhaps you've heard of the Permian extinction? [wikipedia.org]

          In the long run you can throw a billion dollars into a mismanaged charity to completely fail to feed the starving (because all the food is stolen by warlords), or you can possibly secure a future for the human race as a whole.

          And just look how much good saving [wikipedia.org] humanity [wikipedia.org] from war [wikipedia.org] has done in the past.

          I think it's easier to reach Alpha Proxima.
    • But do they continue to pass every experiment at the same time?

    • This isn't exactly what most scientist would consider "good news". We already know that both the standard model and the general relativity are wrong or at least incomplete, but they continue to pass every experiment, including this one...

      If you bothered to read the post you would have noticed:

      The experiment ruled out the simple neutrino oscillation interpretation of the 1990s LSND experiment. Neutrinos have a tiny amount of mass, required by their oscillations, as observed in solar, atmospheric, and reactor neutrino experiments. Combining this mass with the LSND experiment's results required the presence of a fourth but 'sterile' neutrino, breaking the 3-fold symmetry of particle families in the standard model.

      Let me translate this to you: there was an experiment that implied that there must be an additional neutrino not currently accounted by the Standard Model, but the new experiment ruled out this possibility. Okay?

      Neither of the two has much (if anything at all) to do with the general theory of relativity, they neither prove nor disprove it, just with the Standard Model of particle physics.

  • by Anonymous Coward on Thursday April 12, 2007 @08:37AM (#18701463)
    The Los Alamos results seemed fishy, so I think most particle physicists expected the sterile neutrino interpretation to be disconfirmed.
  • by noidentity (188756) on Thursday April 12, 2007 @08:54AM (#18701605)
    "Nice to see some good news out of Fermilab after the CERN debacle"
    So it would be bad news if an experiment showed something you were hoping you wouldn't get? That isn't science. Science is being happy when your experiment successfully tests the hypothesis, regardless of whether it confirmed it or not. A success is in gathering more data, a failure having the experiment give no useful information.
    • Re: (Score:3, Funny)

      by Tx (96709)
      Maybe he meant it's good news because the experiment yielded a useful result, and nothing blew up?
      • by Jugalator (259273)
        What are you, working for an insurance company??
        You need to start thinking like a scientist, and look for the BIG badabooms!

        OK, so I'm really just a bored programmer expressing my urge for more excitement here... :-(
    • More succinctly: If the experiment confirms your hypothesis, it's a "measurement". If the experiment refutes your hypothesis, it's called a "discovery". -- :- Dabe
  • Some background (Score:5, Informative)

    by radtea (464814) on Thursday April 12, 2007 @08:56AM (#18701637)

    Neutrino oscillations are a process by which different types of neutrino can turn into each other. The elementary particles (quarks, leptons and neutrinos) all come in three "families". We are made of the lightest family: up and down quarks (which are the constituents of protons and neutrons) and electrons. Members of the heavier families are unstable and decay rapidly into lighter particles.

    However, it turns out that the weak nuclear interaction can mix quarks of different families. Down quarks turn out to be somewhat mixed with strange quarks of the next heaviest family due to this effect.

    For a variety of reasons, it was natural to ask if neutrinos were mixed in the same way. In particular, this could account for the unexpected deficit of electron-type neutrinos from the sun [queensu.ca]. Various terrestrial experiments were done in the 80's and 90's to try to detect this effect, including LSND.

    Neutrino experiments are extremely difficult and subject to all kinds of backgrounds, making them highly susceptible to errors in calibration and calculation. The LSND results were at odds with everything else that had been seen, but the stakes were high and no one wanted to give up on a result that might be right although it was not widely believed by people outside the LSND collaboration itself.

    The experiment described in TFA has tried to independently reproduce the LSND results. This is somewhat easier to do than the original experiment because you can design things so that you are most sensitive to the most interesting region. They have failed to find the effect that the LSND result would predict if it was due to neutrino oscillations, and it is likely that this is the end of it.

    The article never says so, but the most likely cause of the LSND result is some error in analysis, particularly in accounting for backgrounds and instrument effects. This kind of thing happens, particularly in neutrino physics, where the background processes are fundamentally many orders of magnitude stronger than the effects you are looking for, and have to be designed out with the most excruciating care.
    • However, it turns out that the weak nuclear interaction can mix quarks of different families. Down quarks turn out to be somewhat mixed with strange quarks of the next heaviest family due to this effect.

      All while Odo watches for "just one wrong move".
  • or other people as well think that the magnet explosion was no accident? I bet that now CERN scientist are going to retaliate by aiming their neutrino beam [web.cern.ch] at FermiLab trying to mess with their experiments.
    • You're right, it wasn't an accident, but don't look to Fermilab. Who has the most to lose if we finally figure out the ultimate secrets of the universe? That's right...

      God. The forbidden Tree of Knowledge in the Garden of Eden was just the first barrier. Exploding magnets are just God's way of saying "Discovereth not the Higgs Boson, for in what day soever thou shalt discover it, thou shalt die the death." Of course, the scientists are all like "Yeah yeah, that's what you said about the Tree of Knowled
  • Go to the MiniBooNE web site [fnal.gov] and guess whether the photomultiplier tubes used to detect the event are either 1520 or 1280.
    This could explain an error. At least in their web site, as the correct answer is 42, as everyone knows!
    • by SMQ (241278)
      As the second paragraph says: 1280 inward facing to detect events in the tank + 240 outward facing to detect background events = 1520 total tubes. Not exactly rocket science, that.
  • by PineGreen (446635) on Thursday April 12, 2007 @09:52AM (#18702149) Homepage
    Cosmology predicted that quite some time ago as myself and collaborators show in this [arxiv.org] PRL paper from over a year ago. And there were many other papers with similar conclusions as well... The only problem is that particle physicists never believe cosmologists! :)
    • by Lithdren (605362)
      Its one thing to predict it. its quite another to prove it.
      • by l2718 (514756)
        You are confused. GP does refer to a proof that there is no sterile neutrino as claimed by LSND -- a proof based on cosmological data. The new "proof" is based on accelerator data. Good to see that they both give the same result.
  • Hardly salvaged... (Score:3, Informative)

    by Roger W Moore (538166) on Thursday April 12, 2007 @12:23PM (#18704715) Journal
    Firstly nobody really believed he Los Alamos results principly because some of the collaborators removed their names from the original results paper and published another paper in the same journal issue in which they voiced considerable concern over the validity of the results. If you can't convince your own collaborators it is very hard to convince anyone else.

    Secondly neutrino oscillations are not in the Standard Model and the problem with the LSND result was that it could not be reconciled with the other neutrino mising results from SNO and SuperK. So while this results is still very interesting it simply confirms that a simple neutrino mixing EXTENSION to the the Standard Model may be sufficien without needing to invoke more exotic alternatives.
  • Clarification (Score:5, Informative)

    by perturbed1 (1086477) on Thursday April 12, 2007 @01:20PM (#18705689)
    I submitted this story to Slashdot, but sadly, I see that my original wording has been altered by kdawson. Unfortunately, I do not have a copy of my original post, but I would like to clarify what I *meant*. First of all, I do not consider this "good news" -- but "good results." The MiniBooNE team clearly worked very hard to get here so a big "Congrats" goes out to them. You could not rule out the LSND result, just because "we did not expect it" and "found it fishy." The unexpected results are sometimes the best ones and in science, remember: one scientist's junk is another scientist's signal. The CMB discovery story [wikipedia.org] is the best example to this. Secondly, the neutrino mass indeed does not belong in the standard model, which already several people have pointed out. What belongs in the standard model is the number of lepton families. It is good to see it confirmed that no "sterile" neutrino is needed to explain the results. Yes, cosmologists have had some say in the subject matter already, but it is good to see it confirmed. This is, afterall, how physics is done. "I told you so" is never a good thing to say in physics. You never know what comes out next afterall. I do not believe that Standard Model has been salvaged by this result nor do I want to live with the Standard Model for the rest of my life. There is already plenty of evidence that the Standard Model is not a sufficient model for explaining all the physical phenomena we observe and soon, I hope soon we will have evidence what that new "something" might be. At this point, I would also like to take this chance, as a physicist who works at CERN, to reply to the highly excited conspiracy theorists: Calm down! CERN, Fermilab and other physics labs are not part of corporate America! Yes, of course, I want CERN (and my experiment, in specific) to be the one who finds the Higgs, but I am willing to bet all my fortune, little as that may be, on that Fermilab's calculation mistake was not intentional. Yes, we, physicists are a funny bunch, with lots of things to argue and get excited about. But, we do have a common goal in life, to dig deeper into the mystery of the universe. And a common understanding -- that the truth *will* reveal itself and you can not determine when it does.
    • by Parlyne (884090)
      Now, correct me if I'm wrong; but, it was my understanding that the introduction of sterile neutrinos in no way requires additional families. The most natural thing would simply be to introduce right chiral neutrinos. All neutrinos are SU(3) and U(1)_Y singlets, and a right chiral neutrino would be an SU(2)_L singlet as well. Given that it wouldn't interact under the standard model gauge group, this (or, maybe more correctly, it's charge conjugate) would act as a sterile neutrino. I mean, isn't this bas
    • Oh great! I'm as calm as a cucumber now that I know that there is a common understanding at CERN that the truth *will* reveal itself, although it cannot be determined when... what?

An authority is a person who can tell you more about something than you really care to know.

Working...