TY - JOUR

T1 - Slow-roll inflation in Palatini F(R) gravity

AU - Dioguardi, Christian

AU - Racioppi, Antonio

AU - Tomberg, Eemeli

PY - 2022/6/20

Y1 - 2022/6/20

N2 - We study single field slow-roll inflation in the presence of F(R) gravity in the Palatini formulation. In contrast to metric F(R), when rewritten in terms of an auxiliary field and moved to the Einstein frame, Palatini F(R) does not develop a new dynamical degree of freedom. However, it is not possible to solve analytically the constraint equation of the auxiliary field for a general F(R). We propose a method that allows us to circumvent this issue and compute the inflationary observables. We apply this method to test scenarios of the form F(R) = R + αRn and find that, as in the previously known n = 2 case, a large α suppresses the tensor-to-scalar ratio r. We also find that models with F(R) increasing faster than R2 for large R suffer from numerous problems.

AB - We study single field slow-roll inflation in the presence of F(R) gravity in the Palatini formulation. In contrast to metric F(R), when rewritten in terms of an auxiliary field and moved to the Einstein frame, Palatini F(R) does not develop a new dynamical degree of freedom. However, it is not possible to solve analytically the constraint equation of the auxiliary field for a general F(R). We propose a method that allows us to circumvent this issue and compute the inflationary observables. We apply this method to test scenarios of the form F(R) = R + αRn and find that, as in the previously known n = 2 case, a large α suppresses the tensor-to-scalar ratio r. We also find that models with F(R) increasing faster than R2 for large R suffer from numerous problems.

KW - Cosmology of Theories BSM

KW - Early Universe Particle Physics

U2 - 10.1007/JHEP06(2022)106

DO - 10.1007/JHEP06(2022)106

M3 - Journal article

AN - SCOPUS:85132169953

VL - 2022

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

SN - 1029-8479

IS - 6

M1 - 106

ER -