Inflation

Abstract

The optimistic picture for the explanation of the baryon-antibaryon asymmetry that we apparently obtain with grand unified theories has one serious drawback. In generic theoretical models of a grand unified theory, with the breakdown of symmetry, there develop curious topologically stable field structures that behave like particles with the unification mass m ≈ 10¹⁵GeV/c². These structures are called monopoles. We consider them in more detail in Sect.11.4. Here, we shall refer only to their abundance. In contrast to the ordinary particles that are free to decay at lower temperatures, these quasi-particles are stable. They may annihilate with the corresponding antiparticles, but the minimum abundance predicted by (6.13) should survive. This minimum abundance corresponds to a mass density that is many orders of magnitude too large to fit into the Friedmann balance. In addition, these monopoles would trigger many processes that are not observed. Up to now, the search for monopoles has been in vain. The predicted abundance would imply that the model cannot be applied. The solution is the supposition of some dilution through inflationary expansion.