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In particle physics and astrophysics, weakly interacting massive particles, or WIMPs, are among the leading hypothetical particle physics candidates for dark matter. The term “WIMP” is given to a dark matter particle that was produced by falling out of thermal equilibrium with the hot dense plasma of the early universe, although it is often used to refer to any dark matter candidate that interacts with standard particles via a force similar in strength to the weak nuclear force. Its name comes from the fact that obtaining the correct abundance of dark matter today via thermal production requires a self-annihilation cross section of , which is roughly what is expected for a new particle in the 100 GeV mass range that interacts via the electroweak force. This apparent coincidence is known as the “WIMP miracle”. Because supersymmetric extensions of the standard model of particle physics readily predict a new particle with these properties, a stable supersymmetric partner has long been a prime WIMP candidate.〔Jungman, Kamionkowski and Griest, (Supersymmetric dark matter ), Physics Reports, 1996〕 However, recent null results from direct detection experiments including LUX and SuperCDMS, along with the failure to produce evidence of supersymmetry in the Large Hadron Collider (LHC) experiment〔(LHC discovery maims supersymmetry again ), Discovery News〕〔Nathaniel Craig, (The State of Supersymmetry after Run I of the LHC )〕 has cast doubt on the simplest WIMP hypothesis.〔Patrick J. Fox, Gabriel Jung, Peter Sorensen and Neal Weiner, (Dark Matter in Light of LUX ), Physical Review D, 2014〕 Experimental efforts to detect WIMPs include the search for products of WIMP annihilation, including gamma rays, neutrinos and cosmic rays in nearby galaxies and galaxy clusters; direct detection experiments designed to measure the collision of WIMPs with nuclei in the laboratory, as well as attempts to directly produce WIMPs in colliders, such as the LHC. ==Theoretical framework and properties== WIMP-like particles are predicted by R-parity-conserving supersymmetry, a popular type of extension to the standard model of particle physics, although none of the large number of new particles in supersymmetry have been observed.〔H.V. Klapdor-Kleingrothaus, (Double Beta Decay and Dark Matter Search - Window to New Physics now, and in future (GENIUS) ), 4 Feb 1998〕 WIMP-like particles are also predicted by universal extra dimension and little Higgs. The main theoretical characteristics of a WIMP are: *Interactions only through the weak nuclear force and gravity, or possibly other interactions with cross-sections no higher than the weak scale;〔M. Kamionkowski, (WIMP and Axion Dark Matter ), 24 Oct 1997〕 *Large mass compared to standard particles (WIMPs with sub-GeV masses may be considered to be light dark matter). Because of their lack of electromagnetic interaction with normal matter, WIMPs would be dark and invisible through normal electromagnetic observations. Because of their large mass, they would be relatively slow moving and therefore "cold".〔V. Zacek, (Dark Matter ) Proc. of the 2007 Lake Louise Winter Institute, March 2007〕 Their relatively low velocities would be insufficient to overcome the mutual gravitational attraction, and as a result WIMPs would tend to clump together.〔K. Griest, (The Search for Dark Matter: WIMPs and MACHOs ), 13 Mar 1993〕 WIMPs are considered one of the main candidates for cold dark matter, the others being massive compact halo objects (MACHOs) and axions. (These names were deliberately chosen for contrast, with MACHOs named later than WIMPs.) Also, in contrast to MACHOs, there are no known stable particles within the standard model of particle physics that have all the properties of WIMPs. The particles that have little interaction with normal matter, such as neutrinos, are all very light, and hence would be fast moving, or "hot". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Weakly interacting massive particles」の詳細全文を読む スポンサード リンク
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