Dark Matter Still Hiding

By Sean Carroll | July 20, 2012 10:07 am

After a few provocative hints over the last few years, new results in the search for weakly-interacting dark matter have come up empty. The latest is from XENON100, a liquid-xenon scintillation detector under the mountain in Gran Sasso, Italy. Here are the talk slides by Elena Aprile (pdf) from the Dark Attack conference in Switzerland (via Flip Tanedo).

And here’s the money plot; dark matter mass is on the horizontal axis, interaction cross section between dark matter and nucleons is on the vertical axis. The colorful bands represent the exclusion limits; anything above that is ruled out.

A couple things to note. The blobs scattered around the plot represent those provocative hints I referred to — the tentative evidence from previous experiments that they might actually be seeing something. XENON seems inconsistent with all of them. However, you can only make a plot like this under certain theoretical assumptions. Even if those assumptions are quite likely to be true, it’s hard to be completely definitive about one experiment ruling out another one, unless they’re really using identical techniques (which none of these are). It’s possible, although maybe hard to imagine, that some complicated dark-matter physics can make everything consistent.

The second point is the dark grey area at the bottom right. That represents a bunch of theoretical predictions in supersymmetric models. As Flip cautions, we don’t have a sensible measure on the space of all models, so the blob should be taken as suggestive rather than definitive. But the suggestion is clear: we’ve ruled out some models, but there are plenty that we haven’t yet reached.

Progress continues. XENON100 used 150kg of liquid xenon; the plan is to upgrade to one ton. Once that happens, they should be able to improve the limits on the cross section by a factor of 1000, which will swipe into a much larger region of parameter space. We’ll see what happens.

  • http://gnomonicablog.com Fernando Curiel

    Wow! Where could it be? Like I said, a great time for a physicist to live…

  • http://www.flisser.com Bob F.

    Since the general idea is that the Higgs field interacts with both normal matter and dark matter, is it possible the LHC can detect gravitons (assuming they exist)? I know the LIGO experiment is looking for gravitational waves, but its current incarnation hasn’t found any.

  • Super_earth

    A 130 GeV WIMP like the one suggested by the gamma ray line detected by the LAT in the Fermi gamma ray Telescope should already had been discovered by XENON 100, or that point in the parameter space (i.e. 130 GeV and the cross section derived from Fermi-LAT data) is still outside the sensitivity of the XENON 100 detector?

  • Mark M

    @Bob F.

    Unfortunately, no physically reasonable detector could ever detect gravitons. See here:


    However, although LIGO has not detected gravitational waves, we know they exist due to Binary Pulsar 1913+16. The Nobel Prize in physics in 1992 was awarded for this discovery.

  • Brett

    I know this is skeptical and that I’m being a bit of a jerk, but I gotta say, i think we are wasting our time trying to detect WIMPS. Well, I take that back, you never really waste your time because you always get an answer, even if it’s not the one you want. Still, I don’t think we’ll ever detect WIMPS via the method we are using.

  • Jimbo

    After all the Higgsian glory we’ve all been toasting of late, X100 is A stern reminder of all the disappointments tallied up at the LHC over the last couple of yrs. No evidence for large extra dimensions, mini-black holes, strings, or SUSY, some of which are desperate attempts to circumvent the hierarchy problem. By any realistic appraisal, they’ve all gone up in smoke. It seems the aesthetics of many physicists are just not those of the lord, to paraphrase Einstein. Yet papers continue to be posted daily on the arxiv, in total denial of reality, & the almost religious belief that somehow SUSY & DM will be found, now against all odds.
    Its time for some sober reappraisal of where theoretical physics is going, & how to get the train back on track.

  • Ryan W

    I’ve come up with a theory that offers an explanation for why dark matter exists while explaining the true nature of the Higgs. Please check it out.

  • Brett

    Ryan – All right, you opened the door; can you sum up your theory in layman’s terms? If you have the mathematical proof, then saying the theory in plain english should be fine and keeps your intellectual property secured since the math is what makes a theory valid.

  • forester


    I think one of the lessons worth drawing from the Higgs discovery is that persistence pays off and nature does not give up her secrets so easily. This provides me with hope that within the next few years the dark matter mystery will be solved.

    Speaking of the 130 GeV radiation found by Fermi, has anyone had a chance to look at a recent DM indirect detection paper? In this study the authors used the Fermi telescope to look for the 130 GeV line in six other galaxy clusters. What did they find? They found that the 130 GeV line is present in all of the galaxy clusters observed and reported on in the study. Here is the title of the paper “An evidence for indirect detection of dark matter from galaxy clusters in Fermi-LAT data” (Tempel et al 2012).

    Sean, what are your views on why it seems as though the DM mystery continues to go unsolved? Could the 2010-2020 decade end up being the decade during which the Higgs particle, gravitational waves, and dark matter are found?!

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  • Morphos

    The galactic Tully-Fisher relation between visible matter and the fourth power of asymptotic circular velocity suggests “dark matter.” Trace vacuum anisotropy plus Noether’s theorems allow trace non-conservation of angular momentum, MOND’s 1.2×10^(-10) m/sec^2 Milgrom acceleration. Dark matter is falsifiied within 90 days of a geomeric Eötvös experiment measuring trace parity-odd vacuum anisotropy only acting upon fermionic matter.

    Massless boson photons detect zero vacuum anisotropy, refraction, dispersion, dichroism, or gyrotropy. Modeling fermionic matter with mirror-symmetric theory unleashes furies of parity violations requiring hierarchies of inserted symmetry breakings. Observed vacuum has parity-even isotropies f(x) = f(-x)(toward photons plus parity-odd anisiotropies f(x) = -f(-x), e.g., chirality, acting only upon matter. Einstein-Cartan-Kibble-Sciama gravitation is testably more complete than its subset general relativity.

    Opposite shoes fit with trace different energies into trace chiral vacuum. They vacuum free fall along trace non-identical minimum action trajectories, violating the Equivalence Principle. Eötvös experiments are 5×10^(-14) difference/average sensitive. Crystallography’s opposite shoes are chemically and macroscopically identical, single crystal test masses in enantiomorphic space groups: P3(1)21 versus P3(2)21 alpha-quartz or P3(1) versus P3(2) gamma-glycine.

    Test spacetime geometry with orthogonal atomic mass distribution geometries. Geometric test masses are 99.97+% net active mass (relative nuclear positions). The best composition contrast (Ti versus Be nuclear binding energies) is 0.2397% active mass. Somebody should look at the Noetherean loophole ending dark matter using this 400X more sensitive Equivalence Principle probe. The plural of “anecdote” is not “data,” and data are not information. Look.

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  • Ryan W

    Brett, I’m strictly theoretical. I don’t have the math background or much of the exact knowledge of every of the multitude of theories, mathematics, and experimental data all current theories are based on. I do however have a pretty good grasp on the concepts of quantum mechanics, general and special relativity, thermodynamics, information theory, and complexity theory. In addition I have read and watched a multitude on the leading theories attempting a unified field theory. This being said my theory is more a conceptual framework. As such all I can say is that through a process I call Relativistic Entanglement dark matter and dark energy are the answers to the question of what happens to information seemingly lost in black holes. My theory also describes a Higgs field like ether of sorts that causes things to have mass. I illustrate this theory and its operation in a series of thought experiments. More at http://www.kickstarter.com/projects/irwitte/an-amateurs-cosmological-theory-of-everything

  • http://www.astro.multivax.de:8000/helbig/helbig.html Phillip Helbig

    @13: There doesn’t seem to be any actual information at the URL except “Everything happens everywhere all the time.” :-(

  • Ryan W

    Sorry about your disappointment Phillip but if I just put all my info out there someone could run off with it before I get a chance to publish.
    On another note everything happening everywhere all the time, while seeming to be stating the obvious, takes on a deeper meaning when viewed in the light of possible processes not observable relative to our frame of reference as we pass through space-time.

  • Ed

    Quick question maybe somebody can answer. The limits on the cross sections from Xenon100 and others…do they assume a particular model for dark matter distribution. More specifically, do they use DM halo models to estimate the DM density in our galaxy and extrapolate based on that the DM density at the detector, and then derive the cross section limits based on this estimate?

  • anon

    Great results from XENON100, but a word of caution. These experiments are very difficult, and it is critical that other experiments using different methods continue to challenge and verify both the models and XENON100 itself. Hopefully SuperCDMS-SNOLAB will be fully funded.

  • Bert

    Dark Matter is not missing.

    What is missing and has been AWOL for 40 years is even a single “WIMP”.

    Also missing is the scientific objectivity and judgement of theoretical physicists who insist on no-show “WIMPs” in spite of nature’s many negative verdicts, and almost completely remain ignorant of a far better candidate for the galactic dark matter: primordial black holes.

    Well, there is a new book to be hawked in the near future.

    See the excellent blog “Not Even Wrong” for the real skinny on what is going on.

    Albert Z

  • Marshall Eubanks

    At some point in the relatively near future, this experimental effort will run out of steam, in much the same way that proton decay searches did, unless something is actually detected. I don’t know if even another 2 orders of magnitude increase in detector mass is fiscally realizable.

    It is interesting to note, BTW, that a continued failure to detect WIMPs as Dark Matter is not generally seen as support for alternative models (such as TeVeS).

  • Valdis Kletnieks

    Bert@19: One would expect that if 80% or more of the Milky Way was primordial black holes, we’d see a lot more gravitational lensing events than are in fact observed. If you have an actual theory that explains the discrepancy, I’m sure we’d all love to hear it.

  • shmith

    The quality of the natural sciences on the natural substances, the very essence of the universe, the particle, the Higgs field and Higgs bosons, gene, the big bang, black holes, dark matter, matter and antimatter, particle domain field, mechanical, human The birth of the end of the universe, super new Department, the prehistory of the natural origin, genes and particles of the solar system, models of the universe, the quark model, such as elementary particles, the God particle, relativistic and non-relativistic, and so on and so forth. Global natural scientists are constantly emerging, and experimental detection results of exploration and remarkable achievements. Some 62 kinds of particles have been found, various theories and hypotheses, as well as the deepening of experimental detection, human beings trying to find the true meaning of nature – God particle, everything can be all is well. Folks are looking for in the assiduous God particle or better say that the original of nature, heaven-sent man, gods, to mankind a great inspiration and opportunity, God how? The major achievements of physicists and cosmologists, biologists, chemists, not only the God particle detection was observed, but more importantly: experiments and research, detection and discovery, designed to in-depth explanation and revelation of the God particle, a driving force (the association and causal relationship between gravitation and ultrafine particles, field and ultrafine particles of super-spin vector domain “super-spin sub-and super-spin vector domain field, super-rotation power and super-rotation of movement.” experiments and observed an extremely important , without which everything is nonsense, ready to collapse and we will find the specification of the God particle is not standardized, regular or non-being is the God particle evolution and transmutation, etc. In other words, God is not a single particle or lonely existence of the universe particles and super-spin vector domain field and ultra-roton interaction, mutually cause and effect and the Big Bang, dark matter, super-rotation movement of the God particle (ultra-roton) super-rotation movement domain – field physics formulas, physics equations, mathematical equations, as well as human exploration found only infinite drop of the sea fills the God particle by no means confined to a corner of the limitations of modern scientific instruments, adds to the difficult and errors found. However, <super-roton including norms or norms, standards or standards, concepts and experimental observations have been increasingly in-depth bottom particle primitive super-spin vector particle spin of rotating spin derivative, is the primitive of the particles, and gravitation, the universe was formed, microform and expansion of the symmetric and asymmetric, material and antimatter, the big bang and particle mound did not closely related to this connection can not explain all of nature, but the super-rotation of the spin vector domain —- the field in which to play a major role and function. God particle is no exception.Research and discovery of the particle and the Higgs boson (God particle), with impressive results. The mass of the particle, the end of the particle detection and in-depth study. In fact, the God particle is not traveled alone. His mechanism is super spin vector of substances ——– super spin vector domain — "Key words: super-rotating vector —- super-spin domain — super-rotation of the rotating the super-spin vector – potential "particle super-spin vector theorem, this is where the key to all things primitive. Big Bang, antimatter, gravitational field, the model of the universe, the quark model, genes, particles, gravity, etc., are all closely linked with this. As for the mathematical and physical model, mathematical equations and expressions, as well as ultra-roton —- super-spin domain – Field specifications or not to regulate the expression and the mode it is easy to see.For scientific research and the experimenter in terms of data and evidence to the success or failure. Equations of mathematical physics, the value of the physical and chemical data, formulas, theorems, axioms, laws, rules, derived or deduced verify, (Due to space limitations, the numerical formula theorem, omitted, and after supplement) with the powerful particle detector and a powerful computer (a few years after these experiments, research and detection observed in the depths of the moon, Mars, Milky Way and the universe, the earth and the moon, interstellar space is particularly important, feasible and reliable, so as to further amend the detection experiments and theorems formula, equations of mathematical physics Admittedly, modify or overthrow innovation back more, as the God particle mass and spin, the universe, dark matter, antimatter, genes ultrastructural features, boast model, model of the universe, the gene model, gravity , electronic fields, cosmic mechanics, quantum mechanics, material, originality, force, movement, originality, the God particle and super-spin vector – domain – big Bang, black holes, collapsing interstellar molecules and dust, Ethernet the authenticity of the identification of particles and elementary particles, the initial state of evolution equations of the universe end of the equation, the big bang and big chaos, the birth of the unity of life and refolding, the destruction of the solar system and Earth survival of synchronous and asynchronous, the particles did not find the number and not the discovery of several of interstellar matter, only the big bang and the God particle can create an infinite universe, material world?.. are numerous natural scientific discovery and validation requires historical and spatial long-term test negative or positive. only natural philosophers and theoretical physicists, cosmologists, biologists, chemists, and the hypothesis is not sufficient to prove its natural attributes. in this sense, human cognition and limitations, of course, does not deny that mankind has taken every step of great significance and a sense of victory.

  • http://www.astro.multivax.de:8000/helbig/helbig.html Phillip Helbig

    Albert Z = RLO?

  • http://pages.towson.edu/joverdui/ James Overduin

    Further to forester’s comment: it is interesting that the theoretical grey blobs on this XENON plot occur around m = 60-70 GeV and at m > 200 GeV, leaving a pronounced gap right where we see hints of m = 130 GeV in the Fermi data (see http://arxiv.org/abs/1205.6811 for a good review). The models on this plot are presumably based on minimal SUSY. Non-minimal SUSY can apparently accommodate both the XENON data and a 125 GeV Higgs with m = 130 GeV (see http://arxiv.org/abs/1206.2639). I would love to hear an expert assessment of this.

  • http://juanrga.com Juan Ramón González Álvarez

    This new null result on the detection of dark matter is only one in a large sequence of null results. As shown in


    dark matter does not exist, but it is only a fictitious distribution of mass with anomalous properties.

    You can continue to use this fictitious distribution of mass (DM) as a formal tool in galactic dynamics or in lensing, but evidently any direct search of this fictitious matter will finish with a null result.

  • meh

    It may just be one of those long standing questions. It seems odd because we have advanced our knowledge of the universe so quickly in such a short period of time, but Dark Matter and Dark Energy may be one of those things that will take another 200 years to figure out. We made so many discoveries around the time we started the space programs; it may not be until we begin a Deep Space program that we can actually make measurements accurate enough to understand what’s happening. I know saying that to a physicist is worse than repeatedly kicking him/her in the groin, but it is what it is.

  • http://dispatchesfromturtleisland.blogspot.com ohwilleke

    LHC data rules out a m = 60-70 GeV SUSY WIMP and disfavors greatly a 130 GeV SUSY dark matter candidate.

    The large scale structure of the universe rule out a m > 200 GeV WIMP and prefers a candidate in the KeV mass range which no SUSY theory that wouldn’t have been revealed at LHC already could accomodate.

  • James Salsman

    Valdis Kletnieks @20: What is your source for PBHs requiring additional gravitational lensing events? At the 100,000 solar masses that Frampton et al expect, there would only be a million in the Milky Way, or one per 300,000 stars, which is far too few to result in any substantial number of discernable lensing events. My sources say MACHOs above 15 solar masses would not have been detected by any lensing studies so far.

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  • http://inerton.kiev.ua Volodymyr Krasnoholovets

    When researches do not understand what exactly they are searching for, they can find nothing. They do not understand the structure of the real space, they talk about: black halls, Big Bang, gravitational waves, weakly interacting particles, hot dark matter, could dark matter, Higgs boson, etc. BUT: any of these notions still never being determined correctly. They started from the theorem of everything. BUT: where is your description and determination of primary notions? Or, in other words, you shall start initially from the theorem of something. When primary things are determined, then the theory of everything can be presented in an easy way. And DARK MATTER becomes a conventional gravitational field that unified interacting objects. Field particles of this gravitational field are also field particles of the field of inertia, which takes its origin in quantum mechanics, or more exactly, in subquantum mechanics that describes direct interaction of moving material particles with the space. Who is interested in details, i.e. how dark matter appears from a submicroscopic theory of gravity, can read about it in this work entitled “Dark matter as seen from the physical point of view” Astrophysics and Space Science, vol. 335, No. 2, 619-627 (2011) http://inerton.kiev.ua/37_dark_matter.pdf

  • Faizan sarwar

    Dark matter,matter but dark. what does it means by meaning and also by nature.Every things in this univers has connection to other things,it is an universal thruth.so, dark matter has also connections with visible matter,energy and also with dark energy.
    What are the possibllities?As I think:-
    (1)we know Vsible matters are changable into visible energy.
    Here,a question arises how visible matter created?Nothing else is available to convert into matter accept energy,as both are equivalent.Now,it is predictable that visible matter and visible energy are inter convertable.Hence,according to the law of conservation it is predictable that visible matter and energy are inversly proportional.such that,dark matter and dark energy are also convertable and equivalence to each other.But,
    The question is where are they?
    As, I explained before they must have any character towards matter and energy.What are those ?I think what is gravity and why it exists around masses,who helps light to travel into space?,why even light cannot escapes from black holes?
    And,such many questions can be understandable and i have developed a theory on all these upper discriptions?And, according to my thinking darkness around us is the proof that dark matter is available around us because visible mass and energy is available.Gravity, space and time all belongs to the relation between visible matter and energy and dark matter and energy.

    I know someone can declare me,mad.But,I have strong logics and concepts about upper words but not possible to write here due to large ness.And,I Want to discuss on it .so, i am waiting for replay.

  • Faizan sarwar

    Dark matter exists around matter.how?

    According to newton’s law of gravity.Gravity depends upon four things m1,m2,distance between masses and gravitational constant.If we let that m2 with constant volume and distance is constant and m1 is extremly heavior and larger than m2 Now, between m1 and m2 with distance of ‘r’ there will be some gravitational force of attraction.
    If volume of m1 decreases 100 times and distance is r than what will happen as mass of both objects are same?Definately due to increase in density, gravity will be increased.Now, if by normal codition volume of m1 is increased 100 times gravitational force must be decreased due to decrease in density.
    Thus, it is predictable that gravity depends not only on mass and distance but also on density of matter.
    It shows that space around matter is also related to gravity.space has also property of gravity.
    Now,If space is related to gravity,it can’t be empty it is mustly made up of any particle which has property of gravity.
    How it behaves towards matter for existance of gravity? Due to upper explanation an atom is not empty but it is filled by any particle which shows gravity?so, this particle exists with it’s on density.so,when matter exists it’s removes this particle according to it’s volume.Hence, the displacement of this particle make it more DENSER around the matter.I think this density is called TIME and is responsible for GRAVITY around matter.
    That’s,why around black hole time is slower due to extreme high density and gravity also.
    Question arises by which particle space is made up off.visible energy and and dark energy hasn’t property to show gravity.so,dark matter is the possible option.I think it is true because we can observe darkness in our daily life.Some one can say that where light is not available so the darkness exists.But,A person blind with birth don’t know or our body except eyes don’t know what is darkness?we can observe darkness only by our eyes.so, darkness exists.It’s visibility depends upon luminousity of light.I think it has property towards dark energy as well as visible matter and energy. It has different behaviour that’s why missing.

  • Amateur Scientist

    From an aesthtic point of view I think most scientists have lost track of the foundation for a new physics. At the first moment of the universe, what don’t we assume all coupling constants were equal to unity = 1.0000

    Then things start to make sense, the new cosmology is an evolution something like Gravity: Electromagtetism was 1:1 and a process of graviton decay started the universe based on the linear decline of the fine structure constant so that eventually G/E = reverse exponential function of
    1/1 as it ends up at currently 137.036. In another one hundred million years alpha ( fine structure constant will be 1/138 and the Gravitational force will not have changed enough to effect life processes other than DNA from the 1/137 to 1/138 All the big graviational change ( dG/dE )/dt would have occurred in the COBE era change


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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] cosmicvariance.com .


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