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LHC question

  1. Jan 19, 2008 #1
    So, what will we see at the LHC if the Standard Model is all that there is to physics at this energy scale? What if there is no supersymmetry, no strings, no loops (or at least no emergent behavior that would be seen here)? Are we going to be able to tell if those theories are false pretty immediately?
     
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  3. Jan 20, 2008 #2

    Haelfix

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    If they find a scalar higgs, that would complete the standard model. If they find nothing else it does falsify some models of supersymmetry, most technicolor models, some LeD models, but not all. What it does do is it removes the primary justification for things like 'low energy' supersymmetry in the first place. Namely as a mechanism to bypass the hierarchy problem.

    In the words of a colleague, the hierarchy problem could become the hierarchy fact, and that could mean the end of particle physics as we know it (most people will assume we merely missed something due to experimental reasons). Theres not many 'simple' and elegant ways around that disaster scenario absent some really contrived scenarios that basically trade off undesirable attributes.

    That scenario wouldn't say much at all about the state of string theory, or other theories of quantum gravity, but then again it wouldn't help clarify things either and we'll probably remain stuck in the hands of theorists.
     
    Last edited: Jan 20, 2008
  4. Jan 20, 2008 #3
    So if the Higgs boson is found, then particle physicists can just go home?

    Or is there a lot more to do? I mean, my professor is working on finding an Axion, so what would that do to the Standard Model if it were found?
     
  5. Jan 20, 2008 #4

    ZapperZ

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    If only physics is that easy.....

    There's a huge amount of investigation to be done beyond just looking for the Higgs. This Nature article describes several of them, even if the Higgs isn't found. One should also consider that it is almost impossible to justify the building of a multi-billion dollar facility just to do ONE type experiment that we expect to yield just one result.

    Besides, if all we care about is the finding of the Higgs, then why is Japan still committed in upgrading KEK and its B-factory? There's a lot more about elementary particles and the Standard Model that needs to be studied. The CP violation issue is still very much a hot topic, and the nature of the origin of the proton spin is still being debated. And then there's still a sector of QED that still needs to be studied and verified - the photon-photon collider.

    If there's anything that I have seen in all the years that I've been involved in physics, as soon as you answer one question, a dozen more pop up. We will never run out of things to study.

    Zz.
     
  6. Jan 20, 2008 #5

    malawi_glenn

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    Also why the neutrino has mass, that is not a part of the standard model as far as I know..
     
  7. Jan 20, 2008 #6

    neu

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    Obviously the LHC's purpose extends far beyond just proving/refuting Higgs theory, but would it not be somewhat "unfortunate" for the LHC developers if Higgs events where spotted at the Tevatron, which I believe is still possible if the Higgs mass is <130 GeV ?
     
  8. Jan 20, 2008 #7

    jtbell

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    As I recall, the Standard Model doesn't allow us to predict why quarks and leptons have their specific masses. The Higgs mechanism generates the masses, but with an arbitrary coupling constant which must be different for each particle in order to get different masses for each of them. (at least in the simplest version of the Higgs mechanism.)

    So, originally we had the problem of why neutrinos should have exactly zero mass, i.e. why doesn't the Higgs interact with neutrinos? Now we merely have the problem of why neutrinos have so much smaller masses than the other fundamental fermions.
     
  9. Jan 20, 2008 #8
    Well I knew LHC would be for more than just the Higgs, even if it was the main goal, but I wasn't aware that it was to find more particles or something.

    I'm imagining two guys standing opposite each other in a hall-way holding flashlights.

    Yeah... but I guess I'm kind of worried that if they do find the Higgs boson and everything eventually turns out to be neat, it won't be as cool as if something like String Theory or something even more exotic were true, with like FTL travel, time travel, multiverses, etc.

    I know I know, it's all far-fetched, but it's like your dad taking you to the dentist, and you hoping until you are sitting in his chair that at some point your dad will say "just kidding" and turn around and take you to Disney Land instead.
     
  10. Jan 20, 2008 #9

    ZapperZ

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    If they don't find the Higgs, String theory (or certainly flavors of it) might also be in deep doo doo.

    If they do find the Higgs, I can almost guarantee that they'll find a lot more things they don't understand. Why do you think the ILC was proposed under the assumption that the LHC would have found the Higgs? Don't you think it is kinda strange to propose to build a $8 billion facility AFTER we have found the Higgs if there's nothing significant left to know and investigate?

    Zz.
     
  11. Jan 21, 2008 #10
    Gah, will this EVER end? Everything is just getting so complicated. Such and such particles, so many formulas, etc. Bleah.

    But yeah, I can see what you are saying. Like the article you posted said, trying to persuade politicians to spend billions on a collider just to find one particle and then go home would not have worked.

    So even if they find the Higgs, will other theories keep on chugging? Obviously the ones that depend on there not being a Higgs (if there are any) will die, but other theories will keep being worked on?
     
  12. Jan 21, 2008 #11

    malawi_glenn

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    ok, so you dont like the progress of science?
     
  13. Jan 21, 2008 #12
    How did you extrapolate that from my comment?

    I don't like how it's all getting complicated and seemingly unrelated. I guess I'd like some sort of easy to use formula or something. Thinking you are about to figure something out, only to find out you opened up 5 more questions is a bit disenheartening, you know?
     
  14. Jan 21, 2008 #13

    malawi_glenn

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    I think your sentence speaks for itself.

    Why is it not good that things are complicated? By the way, Physics is about finding the symmetries. So in one way, elementary particle physics is the most naked thing you can study. If everythings was only "one simple formula" then things would probably been found today.

    How many years have you studied physics?
     
  15. Jan 21, 2008 #14
    What is this, a joke? Are you honestly asking why it's bad for something to be complicated?

    I thought the "one simple formula" has always been the goal.

    I'm a Junior now.
     
  16. Jan 21, 2008 #15

    malawi_glenn

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    One UNIFIED theory is the goal.

    But it does not imply its gonna be an easy one, and that not alots of formulas etc are given.

    For example the standard model of Elementary particles as it is today, isnt something you can grasp until graduate studies etc. Very diffcult math and so on. (I mean, try study a book called "Introduction to the standard model och particle physics", and then you'll see that a lots of thins are needed to just understand the very first pages). And depending on which particles you are looking at etc, you have different equations. But the theory is based on one simple symmetry argument.

    Of course the more elegant a solution is, the better there is. But dont mix "elegant" with simple.
     
  17. Jan 21, 2008 #16
    So it doesn't bother you at all that there is more and more stuff you have to memorize, understand, etc, about a given field before you can add anything to it?

    I picked up "Intro to Particle Physics" by Griffiths and quickly put it back down. It's beyond me at this point.
     
  18. Jan 21, 2008 #17

    malawi_glenn

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    Nope, thats why I think it is so fun with modern physics=)

    Intro to particle physics by griffiths is also perhaps the easiest book you can study, it is written for undergraduates.. so Iam at that level now.

    My approach is, the more I learn, the more I also realize that there is more to be learned. And that nature is so exciting and wonderful. Thats why I enjoy modern physics, it is very demanding on the same time as it is very symmetric and beatiful.

    As Zapper said, when we find something new in our experiments, we find also new things that we had no idea that they should exist. So this is the way science goes, it is about exploring the universe: both large scales and on small scales. And something that we find might be useful in a technological sense, and the other things adds new things in our culture and world view.
     
  19. Jan 21, 2008 #18
    Yeah, but wouldn't it have been nice to find an easy way without a lot of complexities?

    Well, hopefully the LHC will start firing in May without any more structural issues.
     
  20. Jan 22, 2008 #19

    malawi_glenn

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    It depends on how you define "complexites".
     
  21. Jan 22, 2008 #20
    The whole field of particle physics is complex. How many particles are there, exactly? There are 6 quarks alone, with things like flavor, strangeness, color, etc.

    If you don't think all of that makes the field complicated, then you simply don't understand the meaning of the word "complex".
     
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