Kinetically modified Palatini inflation meets ACT data

We show that the coexistence of a non-minimal coupling to gravity f R = 1 + c R ϕ n / 2 with a kinetic mixing of the form f K = f R m – where n = 2 and 4 and 0.5 ≤ m ≤ 10 – reconciles chaotic inflation based on the ϕ n potential with the recent ACT results, if we adopt the Palatini formulation of gravity. The attainment of inflation allows for subplanckian inflaton values and energy scales below the cut-off scale of the corresponding effective theory. The model can be also embedded in supergravity by introducing two chiral superfields and a monomial superpotential, linear with respect to the inflaton-accompanying field. Its stabilization is achieved thanks to a compact contribution to the Kähler potential, whose the inflationary part includes an holomorphic logarithmic term and a real one multiplying a shift-symmetric quadratic polynomial term.

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