Theory HEP Seminar

Mixed axion-LSP dark matter from SUSY models with implications for LHC

Howard Baer

University of Oklahoma

SUSY models with WIMP-only cold dark matter (CDM) suffer from the gravitino problem and fine-tuning in the neutralino relic density. If we implement the Peccei-Quinn solution to the strong CP problem within the context of SUSY models, then we obtain a spin-0 saxion and spin-1/2 axino in addition to the axion. In the case where the axino is LSP, then dark matter (DM) is expected to consist of a mixture of axions and axinos. Mixed axion/axino CDM allows for the solution of several cosmological problems while altering expectations for SUSY at LHC. An alternative possibility is that the neutralino is LSP while axino is quite heavy. Enhanced neutralino production from axino decay in the early universe then makes models such as AMSB dark matter compliant, albeit with mixed axion/neutralino CDM.