Superheavy dark Matter
If there exists fields of mass of the order of 10{sup 13} GeV and large field inflation occurs, their interaction with classical gravitation will generate enough particles to give the universe critical density today regardless of their nongravitational coupling. In the standard dark matter scenarios, WIMPs are usually considered to have once been in local thermodynamic equilibrium (LTE), and their present abundance is determined by their self-annihilation cross section. In that case, unitarity and the lower bound on the age of the universe constrains the mass of the relic to be less than 500 TeV. On the other hand, if the DM particles never attained LTE in the past, self-annihilation cross section does not determine their abundance. For example, axions, which may never have been in LTE, can have their abundance determined by the dynamics of the phase transition associated with the breaking of U(1){sub PQ}. These nonthermal relics (ones that never obtained LTE) are typically light. However, there are mechanisms that can produce superheavy (many orders of magnitude greater than the weak scale) nonthermal relics. Some of this is reviewed in reference 2. Although not known at the time when this talk was given, it is now known that if the DM fields are coupled to the inflaton field, then the mass of the DM particles that can be naturally produced in significant abundance after inflation can be as large as 10{sup {minus}3} M{sub Pl} (paper in preparation). The author discusses the gravitational production mechanism which is a generic consequence of any large field inflationary phase ending.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC02-76CH03000
- OSTI ID:
- 755544
- Report Number(s):
- FERMILAB-Conf-98/245-A; TRN: AH200014%%75
- Resource Relation:
- Conference: 6th International Symposium on Particles, Strings, and Cosmology, Boston, MA (US), 03/22/1998--03/27/1998; Other Information: PBD: 25 May 2000
- Country of Publication:
- United States
- Language:
- English
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