All your darkmatter are belong to unparticles

Posted By Pamela on Nov 16, 2007 | 10 comments

Sometimes, in science, English is abused in ways that make one giggle while learning. Earlier today I read an abstract that was so fascinatingly unnatural that I had to read the article.

“Once a parity is introduced in unparticle physics, under which unparticle provided in a hidden conformal
sector is odd while all Standard Model particles are even, unparticle can be a suitable candidate for the cold dark
matter (CDM) in the present universe through its coupling to the Standard Model Higgs doublet.”

No, I didn’t initially understand it either. (My first thought was actually, “All your base are belong to us.” )

But then I read the paper, and found that it was actually very cool. A few months ago, Harvard’s Howard Georgi (who was one of my favorites among the Harvard Faculty I used to work with), came out with a neat theory that in addition to the standard particles in the standard model of physics there is also a secondary particle regime which he called unparticles (see this article and this article). If this stuff exists, it will be detectable by the Large Hadron Collider (LHC) when it stars working at some point in (hopefully) the next 12 months.

And, in this new paper I read, by Tatsuru Kikuchi1, and Nobuchika Okada of The Graduate University for Advanced Studies in Japan, there are indications that if this unparticle stuff exists, it could be dark matter. Specifically, the predict that Higgs bosons (which the LHC will produce) can decay into two dark matter unparticles. They make specific predictions for various possible Higgs boson masses, and they are set to be proven right or wrong by the giant international experiment.

This is the kind of theory I like.

I am amazed at how much people can pull out of mathematics. This all started with Howard Georgi exploring the math a particle physics and finding a door through the equations into unparticles. Now, people are going through this door and exploring possible ways to redecorate our understanding of the universe. This isn’t something I have the ability to do. For me, math is a tool, and things like the quadratic equation have one purpose (like a tiny star wrench) while other equations like F=ma are giant adjustable wrenches that can be used as a hammer in a pinch. I know how to abuse tools (which may be why my husband tries to keep me out of his machine shop), but I don’t have it it me to build new tools that through there existence define a new way of building things. In opening the door to unparticles, Georgi was very much like the first person to make a screw and screw driver – because of the screw and screw driver, it was now possible to build new things, never before imagined.

And we’ll know soon enough if unparticles are real.

I can’t wait for the LHC to fire.


  1. So that’s why the title sounds so familiar!
    I can’t wait for LHC either. I really want to know if Higgs bosons exist. (And I also ‘read’ somewhere, though I might have a bad memory, that LHC might create mini-black holes from proton-proton collisions)
    As for math, I think there’s a universe of its own. I used to find disassembling the dy and dx odd, but now it’s sleight of hand.

  2. You know, the more I read and talk (turns out that one of the current researchers at CERN was one of the “brat kids” that ran around the Engineering Division of USS Accord) the more I see that a whole hell of a lot of hopes are being pinned on the LHC. I hope it can deliver!

  3. Thanks for unravelling that for us Pamela. the last frontier still remains just that, an unknown frontier with many secrets…

  4. Hi Pamela,

    Thanks for this interesting post. I have to admit though I don’t find the unparticle idea particularly compelling. Possible phenomenology isn’t the only thing that matters. I have had a brief post on the Unparticles in September. Best,


  5. Science is definitely a good place to find bad English!

    Oddly enough, of the several papers I’ve published I had my first ever experience of having real English grammar editing with my latest paper due out shortly in Astrobiology (

    I gave my style manual a workout looking up “dangling participle”, “split infinitive” and other dastardly terms.

  6. If there are unparticles, must there be anti-unparticles?

  7. Hi Pamela,

    Thanks for this interesting post and advertising our paper!

    Indeed, a few months ago, we have proposed a possibility for the unparticle as a candidate of the Dark Matter.
    Tatsuru Kikuchi and Nobuchika Okada
    “Unparticle Dark Matter”
    arXiv:0711.1506 [hep-ph].
    I think this is the first paper that tried to explain the dark matter in terms of the unparticle. Basically, the conclusion is as follows: it is indeed possible to explain the observed dark matter relic abundance in terms of unparticle by itself; it is so amazing and so interesting.

    Tatsuru Kikuchi

    Theory Group, KEK
    1-1 Oho, Tsukuba, Ibaraki 305-0801, JAPAN
    E-mail: (“_at_” has to be replaced by @)

  8. Hi Pamela,

    If you are still interested in our work, please let see my talk at the international workshop on the Grand Unified Theories:

    or given at the KEK Annual Theory Meeting on Particle Physics Phenomenology:

    Tatsuru Kikuchi
    Theory Group, KEK
    1-1 Oho, Tsukuba, Ibaraki 305-0801, JAPAN
    E-mail: (”_at_” has to be replaced by @)


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