Scale-invariant quadratic gravity and inflation in the Palatini formalism

@article{58603,
   author = {Gialamas, Ioannis D. and Karam, Alexandros and Pappas, Thomas and Spanos, Vassilis C.},
   article_location = {College Park (USA)},
   article_number = {2},
   doi = {http://dx.doi.org/10.1103/PhysRevD.104.023521},
   keywords = {DARK-MATTER;SYMMETRY-BREAKING;HIGGS;FLATNESS;UNIVERSE;HORIZON;MODELS},
   language = {eng},
   issn = {2470-0010},
   journal = {Physical Review D},
   title = {Scale-invariant quadratic gravity and inflation in the Palatini formalism},
   url = {https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.023521},
   volume = {104},
   year = {2021}
}

TY  - JOUR
ID  - 58603
AU  - Gialamas, Ioannis D. - Karam, Alexandros - Pappas, Thomas - Spanos, Vassilis C.
PY  - 2021
TI  - Scale-invariant quadratic gravity and inflation in the Palatini formalism
JF  - Physical Review D
VL  - 104
IS  - 2
SP  - "023521-1"-"023521-20"
EP  - "023521-1"-"023521-20"
PB  - American Physical Society
SN  - 24700010
KW  - DARK-MATTER;SYMMETRY-BREAKING;HIGGS;FLATNESS;UNIVERSE;HORIZON;MODELS
UR  - https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.023521
N2  - In the framework of classical scale invariance, we consider quadratic gravity in the Palatini formalism and investigate the inflationary predictions of the theory. Our model corresponds to a two-field scalar-tensor theory, which involves the Higgs field and an extra scalar field stemming from a gauge U(1)(X) extension of the Standard Model, which contains an extra gauge boson and three right-handed neutrinos. Both scalar fields couple nonminimally to gravity and induce the Planck scale dynamically, once they develop vacuum expectation values. By means of the Gildener-Weinberg approach, we describe the inflationary dynamics in terms of a single scalar degree of freedom along the flat direction of the tree-level potential. The one-loop effective potential in the Einstein frame exhibits plateaus on both sides of the minimum and thus the model can accommodate both small and large field inflation. The inflationary predictions of the model are found to comply with the latest bounds set by the Planck collaboration for a wide range of parameters and the effect of the quadratic in curvature terms is to reduce the value of the tensor-to-scalar ratio.
ER  - 

GIALAMAS, Ioannis D., Alexandros KARAM, Thomas PAPPAS and Vassilis C. SPANOS. Scale-invariant quadratic gravity and inflation in the Palatini formalism. \textit{Physical Review D}. College Park (USA): American Physical Society, 2021, vol.~104, No~2, p.~''023521-1''-''023521-20'', 20 pp. ISSN~2470-0010. Available from: https://dx.doi.org/10.1103/PhysRevD.104.023521.