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We study multifield inflation in scenarios where the fields are coupled non-minimally to gravity via $xi_I(phi^I)^n g^{mu u}R_{mu u}$, where $xi_I$ are coupling constants, $phi^I$ the fields driving inflation, $g_{mu u}$ the space-time metric, $R_{mu u}$ the Ricci tensor, and $n>0$. We consider the so-called $alpha$-attractor models in two formulations of gravity: in the usual metric case where $R_{mu u}=R_{mu u}(g_{mu u})$, and in the Palatini formulation where $R_{mu u}$ is an independent variable. As the main result, we show that, regardless of the underlying theory of gravity, the field-space curvature in the Einstein frame has no influence on the inflationary dynamics at the limit of large $xi_I$, and one effectively retains the single-field case. However, the gravity formulation does play an important role: in the metric case the result means that multifield models approach the single-field $alpha$-attractor limit, whereas in the Palatini case the attractor behaviour is lost also in the case of multifield inflation. We discuss what this means for distinguishing between different models of inflation.
We revisit the notion of slow-roll in the context of general single-field inflation. As a generalization of slow-roll dynamics, we consider an inflaton $phi$ in an attractor phase where the time derivative of $phi$ is determined by a function of $phi
Non-attractor inflation is known as the only single field inflationary scenario that can violate non-Gaussianity consistency relation with the Bunch-Davies vacuum state and generate large local non-Gaussianity. However, it is also known that the non-
The possibility that primordial black holes constitute a fraction of dark matter motivates a detailed study of possible mechanisms for their production. Black holes can form by the collapse of primordial curvature fluctuations, if the amplitude of th
Stochastic inflation is an effective theory describing the super-Hubble, coarse-grained, scalar fields driving inflation, by a set of Langevin equations. We previously highlighted the difficulty of deriving a theory of stochastic inflation that is in
In this paper, we apply reconstruction techniques to recover the potential parameters for a particular class of single-field models, the $alpha$-attractor (supergravity) models of inflation. This also allows to derive the inflaton vacuum expectation