Exact cosmological solution with particle creation in JBD theory

Exact solutions are sought by taking the generated particles of spin 1/2 (according to the creation rate of Schäfer and Dehnen [1]) as matter sources of the Cosmological equations of JBD theory. There exists one exact solution for which the gravitational constant decreases linearly with time and the mass of the universe increases proportionally to the square of its age (Dirac's hypotheses). The radius of curvature increases linearly with time while the density decreases inversely with it. It is found that for an age of the universe 10^–22 sec only two particles have populated the universe. This is assumed to be the initial state of the model. The calculated present particle number and their density are in agreement with the observed data. This model implies that all present matter (excluding the two initial particles) has been created by the expansion of the universe.Supported in part by CONACYT grant No. 11358.