Lower bounds on axion rest mass in a general cosmological scenario

Abstract

It is shown that, if axions make up the dark matter in the universe, a general lower limit range of 1.07-4.09 x 10 to the -5th eV can be set on the axion rest mass on the basis of consideration of general spacetimes, without recourse to specific assumptions of isotropy and homogeneity which are characteristic of the Friedmann model of the universe. Limits on mass are derived in terms of possible ages for the universe, and the results also set a lower limit range for the vacuum expectation value of the scalar field of 1.15-0.30 x 10 to the 12th GeV. The theory may have application to the setting of general upper limits on the age of the universe