We consider the production of matter and radiation during reheating after inflation, restricting our attention solely to gravitational interactions. Processes considered are the exchange of a graviton, hμν, involved in the scattering of the inflaton or particles in the newly created radiation bath. In particular, we consider the gravitational production of dark matter (scalar or fermionic) from the thermal bath as well as from scattering of the inflaton condensate. We also consider the gravitational production of radiation from inflaton scattering. In the latter case, we also derive a lower bound on the maximal temperature of order of 1012 GeV for a typical α-attractor scenario from φφ→hμν→ Standard Model fields (dominated by the production of Higgs bosons). This lower gravitational bound becomes the effective maximal temperature for reheating temperatures, TRH≲109 GeV. The processes we consider are all minimal in the sense that they are present in any nonminimal extension of the Standard Model theory based on Einstein gravity and cannot be neglected. We compare each of these processes to determine their relative importance in the production of both radiation and dark matter.
Bibliographical noteFunding Information:
The authors thank Marcos García and Kunio Kaneta for useful discussions. This work was made possible by with the support of the Institut Pascal at Université Paris-Saclay during the Paris-Saclay Astroparticle Symposium 2021, with the support of the P2IO Laboratory of Excellence (program “Investissements d’avenir” ANR-11-IDEX-0003-01 Paris-Saclay and ANR-10-LABX-0038), the P2I axis of the Graduate School Physics of Université Paris-Saclay, as well as IJCLab, CEA, IPhT, APPEC, the IN2P3 master projet UCMN and ANR-11-IDEX-0003-01 Paris-Saclay and ANR-10-LABX-0038. This project has received support from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 860881-HIDDeN and the CNRS PICS MicroDark. The work of K. A. O. was supported in part by DOE Grant No. DE-SC0011842 at the University of Minnesota.
© 2022 authors. Published by the American Physical Society..