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In this work we investigate the inflationary phenomenological implications ofa recently developed ghost-free Gauss-Bonnet theory of gravity. The resultingtheory can be viewed as a scalar Einstein-Gauss-Bonnet theory of gravity, so byemploying the formalism for cosmological perturbations for the latter theory,we calculate the slow-roll indices and the observational indices, and wecompare these with the latest observational data. Due to the presence of afreely chosen function in the model, in principle any cosmological evolutioncan be realized, so we specify the Hubble rate and the freely chosen functionand we examine the phenomenology of the model. Specifically we focus on deSitter, quasi-de Sitter and a cosmological evolution in which the Hubble rateevolves exponentially, with the last two being more realistic choices fordescribing inflation. As we demonstrate, the ghost-free model can produceinflationary phenomenology compatible with the observational data. We alsobriefly address the stability of first order scalar and tensor cosmologicalperturbations, for the exponential Hubble rate, and as we demonstrate,stability is achieved for the same range of values of the free parameters thatguarantee the phenomenological viability of the models.

Viable Inflationary Models in a Ghost-free Gauss-Bonnet Theory of Gravity