Saturday, July 19, 2014

CRESST defects from "dark matter is seen" coalition

A year or two years ago, several experiments were claiming the existence of rather similar signals of an apparent dark matter particle lighter than \(10\GeV\). The experimental groups were split almost evenly, to the "Dark Matter Is Seen" allies and the "Dark Matter Is Not Seen" axis.

LUX in South Dakota has totally changed the game 9 months ago and with its precise observations of nothing, it obliterated all the competing experiments that had claimed a signal. Those humiliated "Dark Matter Was Seen" experiments included DAMA, CDMS-Silicon, CoGeNT, and also... CRESST. It didn't become quite clear why they had seen something but with LUX's superiority, it was pretty much guaranteed that what they saw was a mirage i.e. an overlooked or poorly understood systematic effect or background.

As Jester points out, CRESST is no longer an ally and became a LUX-led axis member, too. Incidentally, the LUX experiment itself will be replaced by its king-sized cousin, LUX-ZEPLIN.

In the new paper
Results on low mass WIMPs using an upgraded CRESST-II detector,
they "do not confirm" their previous claims of a signal.

Instead, in the absence of deviations from the background, they impose upper limits and they are summarized by the red line on the graph above. Note that this red line destroys a new region of the parameter space, especially for the WIMP masses below \(3\GeV\) or so – their exclusion actually affects hypothetical particles as light as \(1\GeV\). In this category, CRESST is becoming a leader (boasting the stringest exclusion). This leadership in the low-mass discipline was possible by their usages of \({\rm CaWO}_4\) crystals; it's the oxygen nuclei that make the difference.

I think that virtually no one is really betting on the resurrection of these strong signals from unexpectedly light WIMPs these days. It's possible that other experiments won't try too hard to find or confirm a signal, and they will find out that it's easier to confirm LUX and perhaps to extend its negative results.

Just to be sure, there are lots of other places in the parameter space(s) where the dark matter in general and WIMP in particular may be hiding and it probably is.

By the way, two Florida physicists argue that the right theoretical prediction for the \(W^+W^-\) cross section is higher than previously thought, due to the contribution of "large logarithms" (related to mutually very different jets) that have to be resummed and that are probably overlooked by the Monte Carlo methods. With these large logarithms resummed, they claim a good agreement between the theory and the observations – so the \(W^+W^-\) excess would go away if they are right.


  1. Imo, Dark matter can come in the form of quark alike compound particles or in bunches forming huge compound Quantum knots as the base for interference ball lightning and UFO psarticles found in the LHC and more larger stuff.

    Dark Matter UFO Dust Particles or Quantum Knots in the LHC at CERN ?

  2. Very cute the CaWO4 detector, considering it is something below everyones noses... I never did understood how scintillators work, nevertheless what I read made me the idea that there is plenty of room for further improvement.

  3. Come on... why do you say Kievo regime and not Ukrainian government? Poroshenko and all the MP's where legally and democratically elected. There are no nazis, at least not more than in greek parliament... If you are referring to party Svoboda, than they are not nazi but nationalists and they are minority is parliament and they are not supporting Ukrainian government and they had their own candidate for president. Stop spreading russian propaganda....

  4. ...somewhat least Putin is more predictable and transparent.

  5. arXiv:1407.1052 ends dark matter signals, consistent with arXiv:1306.5534 observing no dark matter within Saturn's orbit.

    But wait! Suppose dark matter is mysteriously repelled by strong gravitation gradients, restricting its presence to interstellar volumes. Yeah, that's the ticket! Uncle Al proposes the demerol as the dark matter quantum providing all necessities, tranquilizing all anxieties, amusing all boredom with only more studies needed.

  6. So money is the reason why the plane got shot down! The route over the area was the most direct route and therefore saved money, and money, as some of us have heard, is what makes the world go-round. I would check to see, when flying, where to fly over in the future. Now, much depends on how insurance companies react to this situation.

    This also shifts the blame from the Ruskies or the Ukes and to the Malaysians. That's because ever since flight MH370, the financially troubled Malaysian Airlines was trying to save money by taking the shortest and most direct routes to conserve fuel for all destinations, including going over warzones and volcanic eruptions.

    There, nobody is to blame except those damn Malays.

  7. Aircrash investigators and the OSCE are unable to get full and unrestricted access to the crash site. They're threatened by pro-Russian rebels; some even fired warning shots with their kalashnikovs. Pictures and videos have emerged which show that these brutes are looting the possessions of the victims. They also transferred bodies and tampered with the evidence, probably in an attempt to hide their involvement. Reportedly, they even recovered the black boxes and these are now gone.

    The international community should immediately demand full and unrestricted access to the crash site. If these beasts fail to comply, several hundred heavily armed commandos should be sent in to deal with these terrorists. With the permission of the legitimate Kiev government, the area around the crash should be secured in a 50 mile radius or so. If Russia once again intervenes, the West should drop its passive stance in this conflict. The U.S. and the E.U. should take on an active role, starting with arms deliveries to the Ukrainian military.

  8. More sanctions! Must have come out of some right wing military intelligence think tank. Sanctions make Russia stronger, more self reliant. Russia does not need the West. I wish someone would put sanctions on the US. Sanctions would have the same effect as tariffs on imports. Sanctions would bring jobs back home as we were forced to again manufacture what we could no longer import. Russia does not need energy or food. Russia can sell energy to the orient and cut off Europe. What is thought to be a game of thrones is a game of fools. Who's running this nightclub?

  9. Bad things will continue to happen in Ukraine, because the psychopaths in charge of western foreign policy lust for blood and destruction. Putin doesn't have a lot of great options.

    Obama loves to kill people. Although all presidents commit mass murder as a matter of their duty to their masters, none of the previous ones to my knowledge personally selected targets for assassination, and none of them to my knowledge deliberately selected a 16-year-old boy for assassination.

    And why? Because he should have had a more responsible father.

    Obama kills children with drones and jokes about killing children with drones. But millions of Americans support him, just as millions of Americans support this psychopathy in Ukraine.

    What an evil, sociopathic society, we have become, ruled by the worst people in the world.

  10. So you are saying that if physics discards moduli for umbilici, a knot not noted cannot bear but button it up?

  11. i think this is a trap

  12. Have you seen Gabor's incredible score?

  13. Yes, it's already two days old. I am following the leaderboard many times a day, just to be sure LOL.

    Already in May, I was considering Gabor the prospective winner although he was somewhere near the 10th rank. Due to his previous successes in similar contests.

    Please post Kaggle-related things under the latest TRF Kaggle blog post which is now July 3rd:

  14. I am not very familiar with button up umbilici , however I am convinced that the cyclic multiverse should have one umbilicus and will go back to it again.

  15. I assume that the Higgs field moduli space is able to produce all sorts of particles even complex quantum knots which could resemble umbilici. All these moduli should be produced by the original big bang umbillicus.

  16. Dear Lubos,

    It has been relatively easy to study theoretical physics on my own. but understanding experimental is much tougher, since I have no access to equipment. Although I do have books and papers, but they seem to assume you know things that are not written and very hard to deduce from the references. So I have few questions regarding experimental physics.

    1. How important is EP(experimental physics) in actual graduate studies.

    2. How much Theoreticians do EP, like do all undergraduates have to go to CERN to see for themselves or do they just trust.

    3. Do Theoreticians actually understand what those thousands of sentimentalists are doing.

    Any other perspective is appreciated.

  17. Dear Qsatheory, I think that undergraduates aren't really divided to experimenters and theorists yet, so future theorists undergo several semesters of lab courses - I surely did.

    I think that theoretical grad students are no longer exposed to experimental physics directly and they may avoid it, so whethert hey're interested in it and get familiar with the real professional experimental work is up to their interests and personality.

    In HEP, phenomenologists are obviously closer to experimenters than formal theorists, and so on.

    Of course that there are tons of grad students who are doing experimental physics and almost nothing else. I would even say that it is a majority!

  18. The DAMA signal has recently been modelled by local neutrons sourced via solar neutrinos plus atmospheric muons. The signals are degenerate to the DAMA signal. They will look for methods to break the degeneracy to sort out which is right, WIMPs or local neutrons. Perhaps they will consider a role for gravitational focusing of the WIMPs. Absence of focusing will support the new interpretation of the signal.

  19. I am afraid that I consider really any politician to be a sociopath until convinced otherwise. Even the benign ones seem to turn to the dark side given time.
    Obama has been one of the most disappointing and surprising---his vindictive and relentless pursuit of whistle-blowers, his support for renditions, political prison camps, drones, and bullying foreign policy contradicts most of his pre-election promises.

  20. Help me with some context here...where is Yulia Tymoshenko in all this? I haven't heard anything about her since her release from prison. Does she represent those who stand for freedom or those who stand for thugs?

  21. sometime ago I was living on Catalina Islands, among other things, and got excited about AIML. Then the following link continues part of the adventure
    If you ask Muzame a question like "Who created you" a jolly answer shall brighten your day. Declassified on Motl's blog :). More fun to come :P

  22. I think he has a girlfriend ;-)

  23. just a a follow up thing. How trusting are those programs that offer degrees that are in "Experimental and Theoretical" fields. Have any students from such programs done significant theoretical work? I honestly am just curious.

  24. Maybe there is just no dark matter:

  25. Ukraine: the plot thickens - Part II

    "That it kept silent, revealing its knowledge about "BUK" only after MH17 had been shot down, puts the Ukrainian government in the frame as responsible for putting the Boeing 777 in harm's way.

    Not least, Ukraine was protecting the revenue from the overflight fees levied on the 350 aircraft transiting each day, amounting to millions each week. But one can only speculate on further motives. The indications are that the government was looking for a "game changer".

    With the separatists in possession of high-performance anti-aircraft missiles, and the air traffic control obligingly routing a stream of airlines over their territory, it could only be a matter of time before the Ukrainian government got its wish.

    In fact, it took a mere three days for that "gamer changer", with the "BUK" system intercepting MH17. Things will never be the same again. And that brings us to the conclusion of Part II.

    Separately, on bomber altitude, since it has been mentioned here: I don't know anything about it but....

    I understand the B-52 has a ceiling of about 50,000 feet and that Hanoi was bombed from 30,000. I doubt that there's an altitude restriction on opening the bomb-bay doors (given that things are pressurised for at least 30,00 feet), or at least I can see no reason for one. So I see no reason why the B-52 couldn't dump its load from any height up to its ceiling. I imagine aiming would be increasingly less accurate with height though, for free-fall munitions anyway, but maybe not a problem if carpet bombing. But all that's over forty years ago.

    I don't see why today's eastern-bloc bombers couldn't match this.

    I wouldn't feel comfortable about potential enemy aircraft at any height.

  26. Today's edition of the local right-wing newspaper sees the propaganda machine cranked up into maximum overdrive space warp. Instead of laying the blame where it belongs, on the criminally negligent bureaucrats who failed to notice the war going on, these have been disappeared. Instead the newspaper is awash with one-dimensional hyperbolic emotionalised drivel blaming the big bad bogeyman PUTIN, PUTIN, PUTIN THE MURDERER. PUTIN, PUTIN, PUTIN, PUTIN THE EVIL SATANIC MURDERER. MORE PUTIN, PUTIN, PUTIN.

    I don't think I've seen anything quite like it. Was the political propaganda this bad during the Cold War, or did some vestige of slight rationality actually prevail during those times.

    The newspaper even prints a one page article from that keen warmonger UK PM David Cameron calling on Putin to stop fomenting war in Ukraine. Why doesn't Cameron call upon Obarma to stop fomenting war in Syria? After all the US is supplying arms to the rebels there with resultant thousands of civilian casualties. Probably Cameron is himself supplying arms to the Syrian rebels. Clearly hypocrisy is a concept of which the editors are totally uncognisant.

    To top it off, there is a ridiculous propaganda piece by Paul Dibb, professor of strategic studies at the Australian National University. The article is headed 'Putin's hand is all over the MH17 catastrophe'. He asserts that Putin may have carried out the incident deliberately in order to close down the air space in Eastern Ukraine. This would detach the area from Kiev's control and help bring it into the Russian sphere of influence.

    I figure it would be pretty easy for Putin to close down the Eastern Ukrainian airspace to commercial overflights merely by closing the extensions of the Ukrainian air routes over Russian territory. The ANU strategic studies department surely leads the world in strategic idiocy.

  27. The Buk-M1 system has a range of up to 45km

  28. Lubos, I thought you might find this interesting: