We consider magnetic monopoles and strings that appear in non-supersymmetric $SO(10)$ and $E_6$ grand unified models paying attention to gauge coupling unification and proton decay in a variety of symmetry breaking schemes. The dimensionless string tension parameter $Gmu$ spans the range $10^{-6}-10^{-30}$, where $G$ is Newtons constant and $mu$ is the string tension. We show how intermediate scale monopoles with mass $sim 10^{13}-10^{14}$ GeV and flux $lesssim 2.8times 10^{-16}$ ${mathrm{cm}^{-2}mathrm{s}^{-1}mathrm{sr}^{-1}}$, and cosmic strings with $Gmu sim 10^{-11}-10^{-10}$ survive inflation and are present in the universe at an observable level. We estimate the gravity wave spectrum emitted from cosmic strings taking into account inflation driven by a Coleman-Weinberg potential. The tensor-to-scalar ratio $r$ lies between $0.06$ and $0.003$ depending on the details of the inflationary scenario.
تحميل البحث