Inflation in supersymmetric SU(5).

We analyze the adjoint field inflation in supersymmetric (SUSY) SU(5) model. In minimal SUSY SU(5) hybrid inflation monopoles are produced at the end of inflation. We therefore explore the nonminimal model of inflation based on SUSY SU(5), like shifted hybrid inflation, which provides a natural solution for the monopole problem. We find that the supergravity corrections with nonminimal Kähler potential are crucial to realize the central value of the scalar spectral index ns≃0.96 consistent with the 7 yr WMAP data. The tensor to scalar ratio r is quite small, taking on values r≲10-5. Because of R symmetry massless SU(3) octet and SU(2) triplet supermultiplets are present and could spoil gauge coupling unification. To keep gauge coupling unification intact, light vectorlike particles are added which are expected to be observed at LHC. [ABSTRACT FROM AUTHOR]