Higgs Territory Continues To Shrink 118
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."
So ... worst-case scenario? (Score:3, Interesting)
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?
Best case scenario! (Score:5, Interesting)
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:Not boring! (Score:3, Interesting)
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:No, it isn't (Score:4, Interesting)
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.
Math != Science (Score:2, Interesting)
Re:Not boring! (Score:5, Interesting)
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.