Dark Matter Particle Candidates Refined
Dark Matter Particle Candidates
No one knows what dark matter is exactly. Whatever dark matter is, though, we do know that it is affecting everything on a universal scale. Dark matter interacts gravitationally with other particles in the universe, but does not interact with electromagnetic radiation (light). This makes it impossible to observe directly. At the moment there are a large number of current theories as to what dark matter is, most involving some combination of MAssively Compat Halo Objects (MACHOs) and/or Weakly-Interacting Massive Particles (WIMPs). These WIMPs are thought to make up most of the dark matter throughout the Universe currently.
A new theoretical framework that explains the types of particles that comprise dark matter in our universe has been proposed by Johnathan Feng and Jason Jumar from the University of California, though. Their paper, Dark-Matter Particles without Weak-Scale Masses or weak Interactions, detailing their elegant model, was released in the most current edition of Physical Review Letters.
While their model’s theoretical particles have the correct thermal relic density, they don’t have weak-scale masses or weak interactions, making it very different from many current models. For this reason they dub it “WIMPless dark matter.” The proposed framework allows for particles masses from 10 MeV to 10 TeV with associated interaction strengths from gravitational to strong.
More traditional theory places the mass of particles comprising dark matter at 100 GeV up to 1 TeV, interacting via a weak-scale force. Because of the greater allowed range in Feng and Jumar’s framework, there is a good possibility that dark matter experiment prospects are much better than initially believed. The last part of their paper examines these different detection prospects with cross sectional scattering theory. The figure above shows several of these proposed detection prospects, plotted on a graph of J, a constant characterizing dark matter halo structure, and GeV, the mass (in energy) of the proposed particle.
They also state that, “LHC evidence .. would exclude neutralino dark matter, but favor WIMPless scenarios.” Meaning theoretical particles described in this theory would be more easily detected. However, they are only optimistic to the point of caution, saying that future experiments at the Tevatron and/or LHC could easily either favor or disfavor their model. The LHC, in particular, is poised to make big discoveries regarding so-called “4th generation” quarks and leptons, which would be a large deciding factor on this theory’s validity. Look for the confirmation when the LHC starts up again, hopefully next year.
Sources:
Feng J., Jumar J. Dark-Matter Particles without Weak-Scale Masses or weak Interactions. Phys. Rev. Lett. 101, 231301
This entry was posted on Monday, December 1st, 2008 at 2:35 pm and is filed under Astrophysics, High Energy. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
Physics News & Science News by Daily Physics » New Detector for Dark Matter December 10th, 2008 at 9:56 pm
[...] scientists work from the theoretical side, producing and analyzing models that describe and put constraints on dark matter. Others are trying to observe these particles using various [...]