Lux et Veritas

There’s an important and interesting paper just out on the arxiv by the Lux Dark Matter Collaboration. Here is the abstract:

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.

For those of you not up with the lingo, a WIMP in this context is a Weakly Interacting Massive Particle, one of the preferred candidates for the dark matter that most cosmologists think pervades the Universe.

The most important thing about the LUX results is that they pretty much exclude results from previous experiments, especially DAMA/LIBRA, that have claimed evidence for dark matter particles at low mass (i.e. 6-10 GeV WIMPS): LUX had expected 1550 dark matter events if the other detections were valid, but could not claim any events that were not consistent with background. They also set new limits on higher mass dark matter, which is 20 times better than previous limits. These new limits are from 85 days of running the experiment; further results will be reported after an additional 300 days in 2014/2015, when the results will increase the sensitivity by a factor of five or so.

So the question is, if LUX is correct, what on Earth is going on at DAMA? Answers on a postcard, or through the comments box, please!

11 Responses to “Lux et Veritas”

  1. I just realized that “in the dark” is not only the opposite of lux, but also the opposite of veritas, as to be in the dark is not to know the truth.

  2. “what on Earth is going on at DAMA?”

    Surely, what in Earth is going on at DAMA?

  3. Read balloon inside balloon theory.

  4. Matthew Penny Says:

    A comment I heard was that with the sensitivity of LUX and XENON threatening to leapfrog them, DAMA had found a budgeton (sadly not my own wit)

  5. Btw, I don’t know if anyone has ever encountered DAMA folks at conferences. I have and I find they are very reluctant to give out full details. when you ask them a question, they answer something completely different as if they couldn’t understand the question.
    I would have thought if they are on the verge of solving the 80 year old dark mystery, they would be much more open and willing to provide all possible details. Certainly for this reason I am very
    skeptical about the DAMA results.

  6. The multiverse theory of space, or why we don’t need dark energy and dark matter. –

    • telescoper Says:

      Unfortunately your video displays a basic misconception of what the Big Bang is and why dark energy and dark matter are needed.

      Whether the Big Bang or some other theory is correct is a question that can only be answered by comparing detailed predictions with observations. Does your “theory” make any quantitative predictions? If not, then it’s not even science..

      • The theory makes two quantitative predictions
        1 That the matter needed to prevent the big bang collapsing back in on itself matches that which can be observed without the need to invent dark matter to explain the apparent missing matter.
        2 That items on the edge of our universe will actually be accelerating as they are being pulled towards other nearby universes.
        Both of these do currently appear to be the case.
        I can go into an indepth discusion of the possible properties and nature of a big bang but I don’t think here is the right place for that.

      • telescoper Says:

        1 is not a quantitative prediction. In fact it is pure gibberish, because dark matter is not “needed to prevent the big bang collapsing back in on itself”.

        2 is not a quantitative prediction either, unless you can say precisely what distance you predict the edge of the universe to lie and what the rate of acceleration would be there?

        While you’re at it, you might like also to explain how you can explain the rotation curves of individual galaxies and gravitational lensing without dark matter, how your model accounts for the existence and properties of the cosmic microwave background, the light element abundances, and so on.

  7. The Secret Experimentalist Says:

    This is a nice result. However, whether you believe in “light” dark matter or not, it doesn’t change anything in a fundamental way: there was already tension between XENON and the various WIMP claims. Though LUX has a lower threshold than XENON, it hasn’t shown a better recoil calibration at low energies.

  8. Dang! With all of this new information coming out about dark matter, higgs, and what-not, I almost can’t WAIT to hear what the results are going to be in a couple of years!

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