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Higgs mass

  1. Jan 14, 2008 #1
    They say Higgs particles are so hard to detect because their mass is so big. But when their mass is so big, wouldn't that make them easier to detect?
  2. jcsd
  3. Jan 14, 2008 #2


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    but harder to produce.
  4. Jan 15, 2008 #3
    High mass means they decay very fast as well, but pam is correct, that the energy level associated with that mass is very hard to come by.
  5. Jan 15, 2008 #4
    But why the need of producing them? Don't they give all particles mass, so shouldn't they be ubiqious?
  6. Jan 15, 2008 #5


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    But then they only exists as virtual particles.

    And HOW would you detect a Higgs from the Higgs field?
  7. Jan 15, 2008 #6
    ahh, this virtual versus real particle business!

    Keep forgetting and misunderstanding it.

    So Higgs is sort of like the gluon field?
  8. Jan 15, 2008 #7


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    Higgs boson is the particle that gives other particle mass, by mediating between the Higgs field and the other fields. Rough speaking. There are also a varaity of models, with different Higgs bosons etc.

    The basic thing one wants to detect is the decay of the (real) higgs boson. A Higgs boson are belived to be created in the proton + anti_proton annihilation at LHC.
  9. Jan 15, 2008 #8


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    In the sense that there is a quantum field associated to the Higgs like there is a quantum field associated to the gluon, to the electron, to each quark, etc.

    So this Higgs quantum field permeates space and the other fields interact with it yielding a mass for all the particles (the massive ones).
    However, this is only indirect evidence. To have a direct evidence of the Higgs field, we want to excite it and produce an observable excitation of the Higgs field which will appear as a Higgs particle. Until we produce and observe an excitation of the Higgs field we won't know it if really exists or if maybe the particle masses are produced by an entirely different process.
    Last edited: Jan 15, 2008
  10. Jan 15, 2008 #9
    Spot on IMO.
  11. Jan 15, 2008 #10
    My question about the Higgs, is why haven't they found it. I mean its mass is < 225 GeV,

    and a lot of the GUTS place it's value a lot smaller. I've seen it being possibly as light as

    115 GeV. I mean with the Z boson particle weighing 91 GeV and the top quark 170 GeV

    it seems like we're in the neighborhood of energies. If the LHC with its combined beam

    energy of 14 TeV doesn't find it?
  12. Jan 16, 2008 #11
    I also like to add one question!

    What particles are they smashing at another to get Higgs particle?
  13. Jan 16, 2008 #12


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    See post #7 in this thread.
  14. Jan 16, 2008 #13
    Last I checked, the LHC is a proton/proton collider.
  15. Jan 16, 2008 #14


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    Yeah that can be true, I might mix it with the FAIR project ;)
  16. Jan 16, 2008 #15


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    LHC is proton-proton.
    Fermilab's Tevatron is proton-antiproton.
  17. Jan 19, 2008 #16
  18. Jan 19, 2008 #17


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  19. Jan 22, 2008 #18
    As I understand things there are people who work on the Tevatron who are actually convinced that the Tevatron is already producing/can produce Higgs Bosons, but that the events are lost among the background noise. If this is true then the Tevatron actually potentially could find the Higgs before the LHC does, but it would be really really hard to do so successfully. Maybe once the LHC finds the Higgs and we know what to look for then we'll be able to see the Higgs resonances in the Tevatron data?
  20. Jan 23, 2008 #19


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    This actually doesn't say much. For something to be convincing in the data, it must be at least a "5-sigma event". It has to be way beyond the background. No one is going to be convinced that it is there if it is barely above it, because a whole lot of things can cause a false signal at that level, and you also can't discount random coincidence. When you have a gazillion data points to deal with, random coincidence is more than likely.

  21. Jan 23, 2008 #20
    Right. In principle Tevatron can produce Higgs, but there are two problems :
    1- the probability to produce a Higgs boson (in the SM) is very small wrt other physics processes. So, the total number of expected events is small.
    2- we need clean signature to disantangle Higgs from other processes (called background). For example H decay to b-bbar is largest probability but the background is so large that people cannot look for this kind of signature.
    The same problems are at LHC, but more events are expected.
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