HIP-2020-22/TH Higgs inflation with the Holst and the Nieh{Yan term Miklos L˚angvik,a Juha-Matti Ojanper¨a,b Sami Raatikainenb and Syksy R¨as¨anenb;c aAsh¨ojdensgrundskola,˚ Sturegatan 6, 00510 Helsingfors, Finland bUniversity of Helsinki, Department of Physics and Helsinki Institute of Physics, P.O. Box 64, FIN-00014 University of Helsinki, Finland cBirzeit University, Department of Physics P.O. Box 14, Birzeit, West Bank, Palestine E-mail:
[email protected], juha-matti.ojanpera@helsinki.fi, sami.raatikainen@helsinki.fi, syksy.rasanen@iki.fi Abstract. The action of loop quantum gravity includes the Holst term and/or the Nieh{ Yan term in addition to the Ricci scalar. These terms are expected to couple non-minimally to the Higgs. Thus the Holst and Nieh{Yan terms contribute to the classical equations of motion, and they can have a significant impact on inflation. We derive inflationary predictions in the parameter space of the non-minimal couplings, including non-minimally coupled terms up to dimension 4. Successful inflation is possible even with zero or negative coupling of the Ricci scalar. Notably, inflation supported by the non-minimally coupled Holst term alone gives almost the same observables as the original metric formulation plateau Higgs inflation. A non-minimally coupled Nieh{Yan term alone cannot give successful inflation. When all three terms are considered, the predictions for the spectral index and tensor-to-scalar ratio span almost the whole range probed by upcoming experiments. This is not true for the running of the spectral index, and many cases are highly tuned.