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Large Underground Xenon dark matter experiment/LHC LSP neutr

  1. Dec 23, 2015 #1
    Large Underground Xenon dark matter experiment and LHC have reported a null result on searches for dark matter, with new bounds.

    What are the implication of these new bounds on neutralinos and LSP?
     
  2. jcsd
  3. Dec 28, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
     
  4. Jan 16, 2016 #3
    Hi kodama:
    Since there been no other replies to your question, I will try to make a useful comment, based on my non-expert interpretation of articles I found by a brief internet search.

    Regarding the LSP.
    https://en.wikipedia.org/wiki/Lightest_Supersymmetric_Particle
    This article says:
    The LSP of supersymmetric models is a dark matter candidate and is a Weakly interacting massive particle (WIMP).
    The article
    http://www.quantumdiaries.org/2014/...-with-the-large-underground-xenon-experiment/
    says no WIMPs were found. Therefore one can conclude that no LSPs were found, and that there is a significant likelihood that they do not exist as a kind of DM.

    Re neutralinos,
    https://en.wikipedia.org/wiki/Neutralino
    seems to be saying that neutralinos are not WIMPs. Therefore it seems reasonable to conclude that the XENON based experiment says nothing about the possibility that neutralinos might exist as a kind of DM.

    Regards,
    Buzz
     
  5. Jan 17, 2016 #4

    mfb

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    Where would such a significant likelihood come from?
    The exclusion limits keep improving, but you can always reduce couplings to make the particles invisible to current experiments.
     
  6. Jan 17, 2016 #5
    what about LHC? no neutralinos detected or produced at 8TEV energies.
     
    Last edited: Jan 17, 2016
  7. Jan 17, 2016 #6

    mfb

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    My post applies to both LHC and direct dark matter searches like XENON.
     
  8. Jan 17, 2016 #7
    lhc is based on finding missing energy. none found.
     
  9. Jan 17, 2016 #8

    MathematicalPhysicist

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    I would think that if dark matter isn't found then perhaps we should be tweaking Newton's laws; I mean besides MOND which is only modifying Newton's laws, perhaps a serious shakeup in the fundamentals of physics is due.
     
  10. Jan 17, 2016 #9

    mfb

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    Missing energy is one part of the signature of possible dark matter-like particles, but the searches are more complex than that.

    No dark matter found so far: sure. It would be impossible to miss such a discovery.
    Every new theory has to satify constraints from thousands of measurements. That is a huge challenge. If you just start making up hypotheses, they will fail to agree with many of those experimental results.
     
  11. Jan 17, 2016 #10
    isnan===
    i can understand how changing coupling constants can evade bounds of lux, but lhc?

    isn't 8 tev enough to create 10-100 gev neutralinos, detected by missing energy?
     
  12. Jan 18, 2016 #11

    mfb

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    Smaller coupling constants reduce the number of events. If the number is small enough, those events get swamped by background events
     
  13. Jan 19, 2016 #12
    Hi @mfb:

    Thank you for pointing out my careless phraseology.

    Perhaps I should have said:
    "there is a significant possibility that they do not exist as a kind of DM.​
    Is this an acceptable statement?

    Regards,
    Buzz
     
    Last edited: Jan 19, 2016
  14. Jan 19, 2016 #13

    mfb

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    Well, something particle-like is quite likely based on cosmological observations, but it does not have to be a supersymmetric particle, sure. Supersymmetry does not have to exist at all.
     
  15. Jan 19, 2016 #14
    what about scalar dark matter? more wave like than particle
     
  16. Jan 19, 2016 #15

    mfb

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    In particle physics such a classification does not make sense. Both "waves" and "particles" are described with the same framework of quantum field theory.
     
  17. Jan 19, 2016 #16
    how adjustable is the coupling for neutralinos and other WIMPS?
     
  18. Jan 19, 2016 #17

    mfb

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    I'm not a theoretician, but in general the phase spaces are usually larger than the exclusion limits experiments can set.
     
  19. Jan 19, 2016 #18
    are you HEP? i ask bc i wonder if ultra-light scalar field dark matter is perhaps the best theory, esp with current exclusion limits from LUX.

    i.e no WIMPS, no DM from 1EV-10TEV

    DM is ultra-light scalar field dark matter. no cuspy halos. perhaps axions as well around 10 kuev

    how would the SM change if they add ultra-light scalar field dark matter ?
     
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