Two of the outstanding problems in astrophysics are the solar neutrino problem and the missing mass problem. The “solar cosmion”, a weakly interacting massive particle, could solve both problems. Several particle physics models have been suggested for the solar cosmion.
The solar cosmion may have other interesting astrophysical effects. It will alter the predicted helioseismology spectrum, effect horizontal branch evolution and may alter the mass-radius relationship in low mass stars. These considerations constrain solar cosmion properties.
Several laboratories have begun an active experimental search for the solar cosmion. The UCSB-UCB-Saclay silicon experiment in the Oroville mine has already placed stringent limits on solar cosmions that couple to matter through spin-independent interactions. A planned Saclay experiment may either detect or rule out the existence of “solar cosmions”.
The Sun is an powerful laboratory for exploring particle physics beyond the standard model. Even if “solar cosmions” do not exist, the Sun can help “illuminate” the search for other weakly interacting particles posited as solutions to the missing mass problem.