What Does an Unparticle Look Like? What is an unparticle?

The hunt for unparticles is on. ‘When the Large Hadron Collider turns on next year, most physicists will be scouring the high-energy data for new particles such as the Higgs boson. Not Howard Georgi of Harvard University in the US, though – he says he is on the look out for a new type of “stuff” altogether called “unparticles”. If it exists, it would mean that our Standard Model of particle physics is not the whole story, and that things other than particles fill the universe (Phys. Rev. Lett. 98 221601).
Unparticles would have properties in common with neutrinos, which have almost zero mass and are therefore nearly scale invariant. Neutrinos barely interact with matter – most of the time physicists can only infer their presence by calculating the “missing” energy and momentum after an interaction. By looking at the same interaction many times, a probability distribution is built up that tells more specifically how many and what sort of neutrinos are involved.
Georgi thinks that a similar technique could be used to search for evidence of unparticles. According to scale invariance, a distribution containing unparticles would become apparent because, oddly, it would look like a distribution for a fractional number of massless particles.’

See also: Professor proposes theory of unparticle physics. ‘Howard Georgi, a physicist at Harvard University, has recently published a paper on so-called unparticle physics, which suggests the existence of “unparticle stuff” that cannot be accounted for by the standard model. Appearing in a recent edition of Physical Review Letters, the paper says that unparticle stuff would be very different than anything seen before.’


  1. From the linked article at physorg.com: http://www.physorg.com/news100753984.html
    Because the signatures of unparticle stuff would be very distinct, LHC experiments have the potential to verify the existence of unparticle stuff immediately. Georgi says that, in his opinion, unparticle stuff would be a more striking discovery than supersymmetry or extra dimensions, both of which point to just more new particles. Unparticle stuff, on the other hand, would be a different concept altogether.
    Hmmm, a more striking discovery than supersymmetry or extra dimensions, eh? Fascinating, but whether we confirm sting theory’s extra dimensions or we have to incorporate a different concept into quantum theory, I think either would entail a new paradigm for the general public and other scientists as well!


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