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Higgs Territory Continues To Shrink 118

Posted by kdawson
from the hoggamus-higgamus dept.
PhysicsDavid writes "Announced this morning by Fermilab, the possible territory for the Higgs boson has shrunk even further. Combined results from the CDF and DZero experiments at the Tevatron have ruled out the existence of the Higgs with a mass between 160 and 170 GeV/c^2 with 95% confidence. At 90% confidence the Higgs is ruled out between about 157 and 185 GeV/c^2. Here is Fermilab's press release. If the Higgs is to be found at the lighter end of the currently allowed range of 114 GeV/c^2 to 185 GeV/c^2, its detection will be harder than at the heavier end due to the kinds of signals that the Large Hadron Collider and the Tevatron will see. Some physicists think that a lighter Higgs will be easier to spot at the Tevatron as the background processes which obscure the faint signal are not as prevalent in those experiments."
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Higgs Territory Continues To Shrink

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  • Boring... (Score:3, Informative)

    by Maury Markowitz (452832) on Friday March 13, 2009 @12:10PM (#27181895) Homepage

    The fact that this is all that's left of high energy physics says a lot. The worst possible outcome is that they actually find the thing.

    • Re: (Score:3, Insightful)

      by Gerafix (1028986)
      It isn't a fact at all in fact. I don't think we can say we know everything that is left to know about high energy physics except the big Higgs.
      • Re:Boring... (Score:5, Insightful)

        by Hordeking (1237940) on Friday March 13, 2009 @12:29PM (#27182193)

        It isn't a fact at all in fact. I don't think we can say we know everything that is left to know about high energy physics except the big Higgs.

        Nah, when they find H, they'll start looking for something else. That is, if they find H. There's no guarantee the model that predicts it is even correct. That's what experimental physics is all about. And usually the answer to your question is another question.

      • > I don't think we can say we know everything that is left to know about high energy physics except the big Higgs.

        No no, I think everyone would agree that we _don't_ know everything. The problem is that the Higgs is the only thing left that we can actually build an accelerator to see. So if we DO find it, then it's going to be the Standard Model for a VERY long time.

        It's a much better outcome if we don't find the Higgs. In that case we need to start some serious soul searching.

        Maury

        • by HTH NE1 (675604)

          So if we DO find it, then it's going to be the Standard Model for a VERY long time.

          At least until the planet finishes collapsing into a nugget of super-dense matter roughly the size of a pea.

    • Not boring! (Score:5, Insightful)

      by Roger W Moore (538166) on Friday March 13, 2009 @01:01PM (#27182709) Journal

      The fact that this is all that's left of high energy physics says a lot.

      The fact that you say this shows that you do not know a lot about high energy physics. Even if the Higgs does exist somewhere in the gap shown there is a huge problem trying to explain why it has such a small mass compared to the scale where gravity is important and the Standard Model has to break down. The chances of this occuring by pure chance are about the same as you winning the UK national lottery for about 5 weeks in a row - if you did that people would not be thinking 'wow you are incredibly lucky' they would be wondering how on earth you cheated the system. Similarly we need to figure out how the universe 'cheated' and made the Higgs mass so light.

      There are also several other questions we need to solve: what is all the dark matter?, what is all the dark energy?, why is there no anti-matter in the Universe?, is the neutrino its own anti-particle?, how does quantum gravity work? etc. etc. You need to remember that so far all of science has been based on the 4% of the Universe made of atoms. 96% of the Universe is made of stuff we do not understand so thinking that the Higgs is all that is left is just crazy talk!

      • Re: (Score:3, Interesting)

        by deglr6328 (150198)

        Is it possible that the parameter space remaining to be excluded could still contain a supersymmetric higgs? There is a video showing Lisa Randall talking about the possibility of finding photinos at the Tevatron but could a SUSY higgs could be found first?

      • Re:Not boring! (Score:5, Insightful)

        by bcrowell (177657) on Friday March 13, 2009 @02:18PM (#27183865) Homepage

        The GP would have been more accurate to say something more limited, like referring to "high-energy physics from the LHC" rather the just "high-energy physics." The painful truth is that the LHC may end up finding essentially nothing of interest. It's possible that Fermilab will discover the Higgs, and absolutely nothing else that's very exciting will ever be found using the general type of accelerator and detector technology represented by these systems.

        It's unlikely that physics in general will ever become a a completely understood subject. However, certain subfields of physics do go extinct. A century ago, a Nobel prize was awarded in physics for the invention of a certain type of lighthouse, and many grad students were still doing their PhD theses on subjects like the motion of a certain type of top on an inclined plane. More recently, low-energy nuclear structure physics is an example of a field that is arguably just a corpse, because the techniques used to study it (such as arrays of HPGe gamma-ray detectors) have reached the point of diminishing returns. It's quite plausible that the same kind of stagnation will now happen in high-energy accelerator physics as currently practiced.

        [...] we need to figure out how the universe 'cheated' and made the Higgs mass so light. [...] There are also several other questions we need to solve: what is all the dark matter?, what is all the dark energy?, why is there no anti-matter in the Universe?, is the neutrino its own anti-particle?, how does quantum gravity work? etc. etc. You need to remember that so far all of science has been based on the 4% of the Universe made of atoms. 96% of the Universe is made of stuff we do not understand so thinking that the Higgs is all that is left is just crazy talk!

        There's a strong possibility that all of these questions will turn out to be ones that can't be answered by LHC-style accelerator experiments. Some of them almost certainly can't be. For instance, the LHC doesn't come anywhere near the Plank energy scale, so there's virtually no chance that it will give any insight into quantum gravity. Dark matter and dark energy probably aren't going to give up their mysteries to particle accelerator experiments, either; that's more likely to happen with astronomy or cosmic ray observations. The only thing that was really guaranteed to happen at LHC energies was that there had to be either a Higgs mechanism or some other, similar mechanism occurring in that energy range, because the standard model sans Higgs is provably not self-consistent in this energy range.

        • Stuff like Dark Matter and Dark Energy is not going to be understood by just studying Astronomy. Fields this big are going to be understood in small steps through many vectors. We'll need more understanding in Cosmology, Particle Physics, Mathematics, maybe even things we beleive we understand like Thermodynamics. Phyics is a field that continually borrows from itself, understanding from one area leads to advances in another.

          The LHC could find super symmetic particles, if it does find any then Mathema
        • Re:Not boring! (Score:5, Interesting)

          by Roger W Moore (538166) on Friday March 13, 2009 @03:19PM (#27184773) Journal

          The GP would have been more accurate to say something more limited, like referring to "high-energy physics from the LHC"....It's possible that Fermilab will discover the Higgs

          Not true. The Tevatron will not get to a 5 sigma discovery significance unless the LHC is delayed by several years more - the best they can hope for is 'evidence' of the Higgs, and event that is somewhat doubtful. However there are very good theoretical arguments that the LHC should be able to reach the Dark Matter scale as well as finding some evidence to explain the Higgs low mass. These are certainly not certainties but they are certainly well motivated possibilities.

          There's a strong possibility that all of these questions will turn out to be ones that can't be answered by LHC-style accelerator experiments.....For instance, the LHC doesn't come anywhere near the Plank energy scale, so there's virtually no chance that it will give any insight into quantum gravity.

          Sorry but you are also wrong here. There are extremely good arguments regarding thermal production of dark matter that suggest the particle cannot have more than ~1TeV mass unless it is not thermally produced. As such it is likely that we will produce it at the LHC and, if not the LHC, it could be produced in a higher energy accelerator since these recreate the conditions just after the Big Bang where the Dark Matter has to be produced (unless you believe a certain amount of Dark Matter was one of the starting conditions of the Big Bang).

          Regarding the Planck scale you only think that it is unreachable because gravity is so weak. If there are extra dimensions of space then the Planck scale might only be a few TeV and then we can do quantum gravity at the LHC. Personally I find this far less likely than finding Dark Matter but it is certianly a possibility. Plus, while the neutrino questions need fixed target or underground experiments to answer these are still particle physics, and there is more to particle physics than the LHC!

          The trap you seem to be falling into is that because there is no guarentee that something will be seen there is no chance of seeing it. While it is certainly true that there is no strong guarentee of seeing more than just the Higgs (or whatever else it might be) there are good theoretical motivations to expect to solve some of these other problems. You cannot say whether it is a strong or weak possibility because we do not know enough to assign any meaningful chance. All we can say is that there is a possibility and there is some good theoretical motivation for such a possibility based on reasonable assumptions. Sometimes those assumptions can of course be wrong...but not always in a 'bad' way.

          • by bcrowell (177657)

            The Tevatron will not get to a 5 sigma discovery significance unless the LHC is delayed by several years more

            I didn't say 5 sigma, you did. Sure, 5 sigma is the gold standard. But suppose Fermilab finds the Higgs at the 2-sigma level, which is 98% confidence, and also measures the mass. Then say the LHC gets a 5-sigma peak, and their measurement of the mass agrees with the previous one by Fermilab. I think any reasonable observer would then have to agree that Fermilab had discovered the Higgs.

            Regarding t

            • Re: (Score:3, Informative)

              by Roger W Moore (538166)

              I didn't say 5 sigma, you did. Sure, 5 sigma is the gold standard.

              5-sigma is not the gold standard it is THE standard to claim discovery. 3-sigma is the significance to claim 'evidence'. Less than 3-sigma and you cannot write a paper that people will take seriously. Yes these are arbitrary standards but they are the standards that the field has adopted.

              You seem to be contradicting yourself here. First you say "I find this far less likely," and then you say that such statements about likelihood are not meaningful.

              Actually I said "Personally I find this far less likely than finding Dark Matter but it is certainly a possibility.". The indication being that I am expressing my opinion (based on the problems that such models have accom

          • by Rich0 (548339)

            Disclaimer - while I find this stuff quite fascinating I'm by no means an expert.

            I've always wondered about whether dark matter could be explained by gravity leakage from other universes nearby in extra-dimensional space. If our universe started out in the vicinity of another universe and gravity could leak between them then you'd expect matter to clump up near concentrations of mass in the other universe. Galaxies in our universe might have been seeded by galaxies in other universes.

            This could also expla

      • Charge and polarity of electromagnetic phenomena are a function of "spin" (quoted, because subatomic particles aren't actually "spinning" in the way most of us intuitively think of spin). The "primordial atom" (if we accept the assertions of Hubble's Big Bang theory) could have had its own "spin" which it imparted to all the daughter particles which were created during the "bang" which gave rise to our known Universe. Not too different from the explaination for why the cosmic background radiation appears
        • by Rich0 (548339)

          Of course, then you'd need to explain why the matter and antimatter were so non-uniformly distributed that you can have entire galaxies composed of one or the other but not both separated by huge voids of empty space.

          However, you could very well be right - if you can imagine a mechanism that gives preference to one vs the other you could imagine that it might work differently in different enviornments.

        • Charge and polarity of electromagnetic phenomena are a function of "spin"

          Sorry but they are not. The weak hypercharge does depend on the spin (or rather the helicity) but the electric charge in no way depends on spin. A right handed electron has exactly the same electric charge as a left handed electron and will undergo identical electromagnetic interactions.

          That said, restated, your argument is effectively that maybe Big Bang just started with more matter than anti-matter. This is certainly a possibility that cannot be ruled out. However we do actually see a difference betw

      • by DG (989)

        Similarly we need to figure out how the universe 'cheated' and made the Higgs mass so light.

        Because if it didn't, we wouldn't be here to observe it?

        DG

      • > The fact that you say this shows that you do not know a lot about high energy physics

        Pfft, try harder.

        The only reason we're looking for the Higgs is because we can. We simply don't have any other HEP we can do. Every alternative theory so far needs energy levels at least an order or two of mag more than LHC to even approach usefulness, and that's simply not going to happen any time soon. Oh, we've tried, but we've failed. I still have a soft spot in my heart for the surfatron, but that's just because o

        • Re: (Score:3, Informative)

          by Roger W Moore (538166)

          The only reason we're looking for the Higgs is because we can. We simply don't have any other HEP we can do. Every alternative theory so far needs energy levels at least an order or two of mag more than LHC to even approach usefulness

          I return to my remark that the fact that you say this shows that you do not know a lot about high energy physics. The reason we are looking for the Higgs is because we have not found it and must find it soon or rule it out which would completely turn the field on its head. Assuming that we do find it there is something called the hierarchy problem that means there is VERY likely to be some new physics below ~10TeV and in reach of the LHC. In addition there is the thermal production argument for Dark Matter

    • There is far more to HEP than the Higgs but that is all the popular press cares to focus on or that you seem to pay attention to. Here is just one recent example: http://dorigo.wordpress.com/2009/03/13/cdf-discovers-a-new-hadron/ [wordpress.com]

  • by Tumbleweed (3706) on Friday March 13, 2009 @12:24PM (#27182119)

    What are the implications for NOT finding the Hggs Boson? Will it be a case of "We know it exists, we just can't find it", or will it be more about figuring out what's what if it doesn't really exist?

    • by n0mad6 (668307) on Friday March 13, 2009 @12:30PM (#27182213)
      No, there's no guarantee a *Standard Model* Higgs Boson (which is what this search is) even exists. We know some mechanism exists for the symmetry that's broken between the Electromagnetic and Weak forces, but that doesn't necessarily have to be in the form of a standard model Higgs.
      • I bet there'll be a few red faces if some people are forced to admit they got their sums wrong... :-)
    • Re: (Score:3, Funny)

      by MouseR (3264)

      What did they expect after calling it the God particle? That it would just reveal itself out of oblivion?

      Leave that to the creationists and remarket the Boson!

      • by Tumbleweed (3706)

        Leave that to the creationists and remarket the Boson!

        The new Bose On(tm) particle - it's the best-sounding particle ever! It's so good, they named two physicists after it!

        • it's the best-sounding particle ever!

          I don't think so. After all, the saying goes: "no highs, no lows, you know it's Bose".
      • by mbkennel (97636)

        I've heard Leon Lederman wanted to call it the "goddamn particle" because dealing with was turning out to be such a bitch, but the book publisher made him change the title.

      • Leave that to the creationists and remarket the Boson!

        Put lipstick on it and call it the Boson's Mate!

    • Best case scenario! (Score:5, Interesting)

      by Roger W Moore (538166) on Friday March 13, 2009 @01:06PM (#27182783) Journal

      What are the implications for NOT finding the Hggs Boson?

      Not finding the Higgs is the BEST scenario because it means that what we think we know is all wrong and that means that the Universe does things a different way and once we figure out what that is there will be a whole realm of new and exciting possibilities to explain some of the other stuff that we do not understand.

      What is great about the LHC is that we have to start seeing evidence either for either the Higgs or something else. The Standard Model literally breaks down and starts to make no sense at all arounf 1TeV in energy: without the Higgs it predicts certain interactions will happen more than 100% of the time! Hence we either have to see the Higgs or something else if the Higgs does not exist.

      • Re: (Score:2, Funny)

        by Anonymous Coward

        Not finding the Higgs is the BEST scenario

        Unless, of course, it really does exist.

        • Unless, of course, it really does exist.

          You cannot have the Standard Model Higgs exist and yet not be found at the LHC....unless the Universe starts to play silly buggers with the laws of probability which in itself would be a result many have long suspected!

      • The Standard Model literally breaks down and starts to make no sense at all arounf 1TeV in energy: without the Higgs it predicts certain interactions will happen more than 100% of the time! Hence we either have to see the Higgs or something else if the Higgs does not exist.

        Or there has to be some other mechanism to prevent interactions above 1TeV. B-)

        (Not bloody likely, of course.)

    • by sjames (1099)

      While absence of evidence is not evidence of absence, it does point that way if there has been a concerted effort to find it.

      Some will cling to the notion that we just haven't found it yet, others will propose new models that either don't call for higgs, show it to be 'somewhere' we haven't looked (meaning requiring higher energy interactions than we have been able to achieve), or otherwise explain why we wouldn't have seen it. Experiments will be devised and run to test predictions of the new models. If th

  • Easier vs. Harder (Score:5, Informative)

    by n0mad6 (668307) on Friday March 13, 2009 @12:29PM (#27182197)
    Its not a matter of "some thinking"-- the backgrounds that swamp a Higgs signal for a low mass Higgs are simply more prevalent at the energies of the LHC. The LHC makes up for that by being able to accumulate much more data than the Tevatron in a shorter amount of time. Of course, up to probably early next year, we at the Tevatron are in a superior position in that any data is greater than the zero the LHC will have accumulated.
  • Somebody needs to keep those folks over at CDF in check. ;->

  • Wow! (Score:5, Funny)

    by Bruce Perens (3872) * <bruce@perens.com> on Friday March 13, 2009 @12:45PM (#27182433) Homepage Journal
    This is so cool! I get a hadron just thinking about it :-)
    • Re: (Score:1, Funny)

      by Anonymous Coward

      This is so cool! I get a hadron just thinking about it :-)

      Too small to be seen with the naked eye, with a lifetime measured in nanoseconds, and the only evidence of it's solitary passing a few droplets left behind in the lonely vacuum of a cloud chamber?

    • Hey! Hey! None of that now! Stay behind the fence!
  • Unplug the microwave in the break room.

  • by escay (923320)
    what do you mean, like laundry?
  • Is it weird that I want Fermilab to find the Higgs boson - rather than CERN - just out of patriotism?
    • It's perfectly understandable. While I don't want the Higgs to exist, not because I'm unpatriotic, but out of sheer perversity. I really don't like the way physics is going, with all this speculation about tiny dimensions, strings and multiple universes, and I would really like us to find out that Nature (anthropomorphic personification, I know, I know) is indeed fundamentally simple.
      • I hold out a great deal of faith that we will discover something fundamental about the universe just as simplistically beautiful as Euler's identity [wikipedia.org]. Strings and 10 dimensions really does seem messy and inelegant, I too want there to be a "better" model.

        • If we can find the truth, that will be enough.

          'Beauty is truth, truth beauty,-that is all
                  Ye know on earth, and all ye need to know.'

      • Re:No, it isn't (Score:4, Interesting)

        by Chris Burke (6130) on Friday March 13, 2009 @02:53PM (#27184349) Homepage

        Uh, well, yeah, except the universe as we know it is already pretty complex (there are a great many particles already known to exist), and not finding the Higgs would up-end one of the nicest and simplest parts of our current understanding, which is to say symmetry (and lots of other aspects of the Standard Model). The new theory would probably end up being much more complicated to explain why symmetry exists in some cases but not others.

        Kinda like how when we figured out Newton's Theory was inaccurate, what replaced it was much more complicated and frankly much weirder. Light travels at a constant velocity relative to all inertial observers? Traveling near the speed of light or a large gravity well alters mass, length, and the relative passage of time? And since we've experimentally verified most of these effects, whatever theory replaces Relativity will probably be even more complicated and more strange to explain both the known effects and whatever anomalies arise to show Relativity to be wrong.

        It's possible that at the core there's a Theory of Everything where one simple equation explains all the emergent behaviors that every other theory tries to explain. But it isn't a given, we're a long way from that, and not finding the Higgs will open a doorway to many new possibilities, lots of em plenty damn complex. Hell one of the things that attracts physicists to String Theory is that it is, relatively speaking, mathematically simple and elegant.

        Be careful what you wish for, is what I'm saying.

        • by cnettel (836611)
          While relativity is less down to earth and certainly less straightfoward (some puns intended) from a common sense perspective, there is also some inherent beauty in it, one of them being exactly that constant speed of light and the limiting of speed. With some success, one might even arguee that it is only marginally more complex, until you try to frame it in a way suitable to approximating a Newtonian mind in "non-relativistic" conditions. Then, by necessity, everything else is expressed as correction term
    • by zizzo (86200)

      No, most Americans think the same thing. I don't think anyone at Fermilab or CERN thinks that way because it tends to be a lot of the same people. They're all physicists and they all want to run the experiments and get on with science.

      They do want to get their names on papers & articles though.

    • No, but keep in mind both CERN and Fermilab have giant collaborations with members from all of the world making important contributions.

      One of the primary reasons I want Fermilab to find (or rule out) a SM Higgs is so that the community here in the US continutes to get funding. Unlike a lot of other government supported projects, one can't just turn the spigot on and off for physics research. It takes years/decades to train not just theorists but the experimentalists too and those industries which support

  • Higgs boson is the particle of the gaps.

  • Lol (Score:3, Funny)

    by jayhawk88 (160512) <jayhawk88@gmail.com> on Friday March 13, 2009 @03:08PM (#27184579)

    At 90% confidence the Higgs is ruled out between about 157 and 185 GeV/c^2

    Man I am going to win so many bar bets this weekend...

  • Math != Science (Score:2, Interesting)

    by czarangelus (805501)
    This is such a stupid pursuit. Mathematics is not science! Math and science work around totally different lines. Academia needs to return to natural philosophy - first make observations, then make a theory for those observations, and then test that theory by experiment. Mathematics is not testable any more so than formal logic. Physics has gone off the rails since Einstein, postulating all kinds of absurd entities with no evidence whatsoever except "the math doesn't work." I mean, the argument for dark mat
    • Re:Math != Science (Score:4, Insightful)

      by Baron_Yam (643147) on Friday March 13, 2009 @03:40PM (#27185029)

      The math is a model of our current (science-derived) understanding of things.

      If the math turns up results we have yet to observe (or observe the lack of) then we look. Because there are two possibilities - the math is wrong or it's pointing to something new.

      Either way, it's science. Observe, theorize, and test are all in there. The math is just a tool.

    • by itsdapead (734413)

      Physics has gone off the rails since Einstein, postulating all kinds of absurd entities with no evidence whatsoever except "the math doesn't work."

      Ever since Newton, math has been fairly crucial to making and testing theories in Physics. However, as long as Physics was dealing with subjects which could be usefully envisioned in terms of nice, human scale machines with rolling balls and pendulums and stuff, anybody could take an interest in the "qualitative" side and build a nice little brass model with balls and springs that showed the principle.

      Trouble is, when you start dealing with the very tiny, or the very large, or something that happened 0.00

    • by cnettel (836611)

      Now, we have this huge theory, based on old observations. It's called the Standard Model. It predicts some particles we haven't seen (yet). So, we devise experiments where those particles are likely to appear and be detectable. The language of the model is mainly mathematics. Naturally, we need some kind of framework and the general principle of (philosophical, not mathematical) induction to be able to devise any experiment not precisely coinciding with observations already made.

      Doing experiments by plain

  • But that Barbara Alvarez from Fermilabs is my kind of geek hottie!

  • What about the possibility that the Higgs doesn't exist? How would that be proved?
    • The theory being tested predicts that the particle will be found somewhere in a specific energy range. Eventually the entire range will have been examined and the particle either found or ruled out.

We warn the reader in advance that the proof presented here depends on a clever but highly unmotivated trick. -- Howard Anton, "Elementary Linear Algebra"

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