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Updated: May 9, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
New constraints on the early expansion history of the universe
Alireza Hojjati1, Eric V Linder, Johan Samsing
1Institute for the Early Universe WCU, Ewha Womans University, Seoul 120-750, Korea.
Abstract:
Cosmic microwave background measurements have pushed to higher resolution, lower noise, and more sky coverage. These data enable a unique test of the early Universe's expansion rate and constituents such as effective number of relativistic degrees of freedom and dark energy. Using the most recent data from Planck and WMAP9, we constrain the expansion history in a model-independent manner from today back to redshift z=10(5). The Hubble parameter is mapped to a few percent precision, limiting early dark energy and extra relativistic degrees of freedom within a model-independent approach to 2%-16% and 0.71 equivalent neutrino species, respectively (95% C.L.). Within dark radiation, barotropic ether, and Doran-Robbers models, the early dark energy constraints are 3.3%, 1.9%, and 1.2%, respectively.
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