January 26, 2006

Dark Sector of the Universe the Henan Way

The dark sector, energy and matter, of the universe is under intensive study these days for good reasons. A proposal for the dark stuff comes from Henan, China (some 400 km to the east of Shanghai). Mian Wang sets up an alternative GR with an additional scalar field (phi). Other scenarios mentioned by Wang include cosmological constant, of course, quintessence, dilaton, axion, tachyon, phantom field, and Chaplygin gas. Like the last in the list, Wang's model offers unified description of both dark energy and matter in succeeding cosmological evolution stages, starting from the inflationary period. His action is this (it should appear in your browser).

In this model the universe is created from the instanton solution, discussed in a previous paper by the author, of field phi when the field is dropped in the left potential well for negative phi. During the period of exponential inflation lambda(phi) provides a large cosmological constant. The inflation ends dynamically when rho + 3p ~ rho_phi + 3p_phi increases from −2rho_phi to zero. A graceful exit from inflation is claimed. After inflation of the early universe the scalar field behaves like cold dark matter, and the universe expands according to 2/3 power law. It looks promising. We shall see whether these arguments will be substantiated by the cosmological community.