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Interpretation of LUX result

  1. Oct 30, 2013 #1

    bcrowell

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    An article in Nature reports a negative result from the LUX experiment's attempt to directly detect dark matter:

    http://www.nature.com/news/no-sign-of-dark-matter-in-underground-experiment-1.14057

    Can anyone give some context? How does its sensitivity compare with that of previous experiments of this type? Are the different experiments sensitive to different things (e.g., WIMPs with different masses)? Is there a preprint on arxiv?
     
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  3. Oct 30, 2013 #2

    marcus

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    Have a look at this:
    http://arxiv.org/abs/1310.5217

    It's a pretty nice short review paper, I think. Only 9 pages and covers most of the direct and indirect detection experiments that had reported by the middle of this year.

    Based on the rapporteur summary talk at recent conference.

    Dark Matter 2013
    Marc Schumann
    (Submitted on 19 Oct 2013)
    This article reviews the status of the ... evolving field of dark matter research as of summer 2013, when it was discussed at ICRC 2013 in Rio de Janeiro. It focuses on the three main avenues to detect WIMP dark matter: direct detection, indirect detection and collider searches. The article is based on the dark matter rapporteur talk summarizing the presentations given at the conference, filling some gaps for completeness.
    9 pages, 7 figures. To appear in the proceedings of ICRC 2013
     
    Last edited: Oct 30, 2013
  4. Oct 30, 2013 #3

    bcrowell

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    Thanks for the link, Marcus, but it doesn't seem recent enough to discuss the LUX result.
     
  5. Oct 30, 2013 #4

    cristo

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  6. Oct 30, 2013 #5

    marcus

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    That's right Ben, LUX had not reported at the time (Summer 2013) the conference was held. But you were asking for context of other studies, their sensitivities etc. The other studies, at least, are discussed.
     
  7. Oct 30, 2013 #6

    marcus

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    Now there's a great source about the LUX experiment itself!
    First results from the LUX dark matter experiment at the Sanford Underground Research Facility
    LUX Collaboration: D.S. Akerib, H.M. Araujo, X. Bai, A.J. Bailey, J. Balajthy, S. Bedikian, E. Bernard, A. Bernstein, A. Bolozdynya, A. Bradley, D. Byram, S.B. Cahn, M.C. Carmona-Benitez, C. Chan, J.J. Chapman, A.A. Chiller, C. Chiller, K. Clark, T. Coffey, A. Currie, A. Curioni, S. Dazeley, L. de Viveiros, A. Dobi, J. Dobson, E.M. Dragowsky, E. Druszkiewicz, B. Edwards, C.H. Faham, S. Fiorucci, C. Flores, R.J. Gaitskell, V.M. Gehman, C. Ghag, K.R. Gibson, M.G.D. Gilchriese, C. Hall, M. Hanhardt, S.A. Hertel, M. Horn, D.Q. Huang, M. Ihm, R.G. Jacobsen, L. Kastens, K. Kazkaz, R. Knoche, S. Kyre, R. Lander, N.A. Larsen, C. Lee, D.S. Leonard, K.T. Lesko, A. Lindote, M.I. Lopes, A. Lyashenko, D.C. Malling, R. Mannino, D.N. McKinsey, D.-M. Mei, J. Mock, M. Moongweluwan, J. Morad, M. Morii, A.St.J. Murphy, et al. (38 additional authors not shown)
    (Submitted on 30 Oct 2013)
    The Large Underground Xenon (LUX) experiment, a dual-phase xenon time-projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota), was cooled and filled in February 2013. We report results of the first WIMP search dataset, taken during the period April to August 2013, presenting the analysis of 85.3 live-days of data with a fiducial volume of 118 kg. A profile-likelihood analysis technique shows our data to be consistent with the background-only hypothesis, allowing 90% confidence limits to be set on spin-independent WIMP-nucleon elastic scattering with a minimum upper limit on the cross section of 7.6×10−46 cm2 at a WIMP mass of 33 GeV/c2. We find that the LUX data are in strong disagreement with low-mass WIMP signal interpretations of the results from several recent direct detection experiments.

    Just posted on arXiv a few hours ago! Thanks Cristo!
     
  8. Oct 30, 2013 #7

    bcrowell

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    So maybe the relevant comparison is fig. 5 of http://arxiv.org/abs/1310.8214 versus fig. 2 of http://arxiv.org/abs/1310.5217 . This seems to show that for the kinds of masses being considered (10 to 1000 GeV), LUX is superior in sensitivity to all previous experiments, and contradicts previous claims of a positive result.

    Is there any reason that WIMP masses should be in this range, or is this just the range of masses that experiments are sensitive to? Is there a simple way to understand why these experiments are most sensitive to masses of about 30-50 GeV?

    Is there any reason why dark matter can't consist of completely sterile particles that only interact through gravity?
     
    Last edited: Oct 30, 2013
  9. Oct 30, 2013 #8

    Vanadium 50

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    Yes, that's what they say.

    Sensitivity peaks at approximately the mass of the target nucleus. A nucleus that is too heavy doesn't recoil much, and one that's too light can't absorb much energy and momentum from the dark matter particle.

    Nope. Gravitinos would do that. But it would really suck.
     
  10. Oct 31, 2013 #9

    Astronuc

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  11. Oct 31, 2013 #10

    bcrowell

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  12. Oct 31, 2013 #11

    ZapperZ

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    BTW, we should also put this result (or null result) together with the recent result from AMS that did detect excess positrons.

    http://physicsworld.com/cws/article/news/2013/apr/04/ams-confirms-positron-excess

    Of course, it is still a ways away from connecting this to dark matter inhalation, but if they are detecting the same type of WIMPs, this will make for a very interesting next couple of years.

    Zz.
     
  13. Oct 31, 2013 #12

    Haelfix

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    light sterile Gravitinos, are already quite constrained by various cosmological constraints and typically require extra physics in order to satisfy experiment (for instance, they often require a nonstandard cosmology to dilute the relic density if they are beyond a certain mass range). Still they are a well motivated possibility and can be made consistent with experiment, although it would be rather unfortunate since they are effectively invisible to both direct and indirect detection, as well as being very difficult to probe at the LHC.
     
  14. Oct 31, 2013 #13

    Vanadium 50

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    Actually, a great number of SUSY models have trouble with dark matter overclosing the universe. A philosophical question is how much information one can gather about the one correct model by studying the properties of the N-1 incorrect models.
     
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