Generalizing the Bogoliubov vs Boltzmann approaches in gravitational production
Ayan Chakraborty, Simon Clery, Md Riajul Haque, Debaprasad Maity, Yann Mambrini
arXiv:2503.21877v1 Announce Type: cross
Abstract: We investigate the spectral behavior of scalar fluctuations generated by gravity during inflation and the subsequent reheating phase. We consider a non-perturbative Bogoliubov treatment within the context of pure gravitational reheating. We compute both long and short-wavelength spectra, first for a massless scalar field, revealing that the spectral index in part of the infrared (IR) regime varies between $-6$ and $-3$, depending on the post-inflationary equation of state (EoS), $0leq w_phileq1$. Furthermore, we study the mass-breaking effect of the IR spectrum by including finite mass, $m_{chi}$, of the daughter scalar field. We show that for $m_{chi}/H_{rm e} gtrsim 3/2$, where $H_{rm e}$ is the Hubble parameter during inflation, the IR spectrum of scalar fluctuations experiences exponential mass suppression, while for smaller masses, $m_{chi}/HearXiv:2503.21877v1 Announce Type: cross
Abstract: We investigate the spectral behavior of scalar fluctuations generated by gravity during inflation and the subsequent reheating phase. We consider a non-perturbative Bogoliubov treatment within the context of pure gravitational reheating. We compute both long and short-wavelength spectra, first for a massless scalar field, revealing that the spectral index in part of the infrared (IR) regime varies between $-6$ and $-3$, depending on the post-inflationary equation of state (EoS), $0leq w_phileq1$. Furthermore, we study the mass-breaking effect of the IR spectrum by including finite mass, $m_{chi}$, of the daughter scalar field. We show that for $m_{chi}/H_{rm e} gtrsim 3/2$, where $H_{rm e}$ is the Hubble parameter during inflation, the IR spectrum of scalar fluctuations experiences exponential mass suppression, while for smaller masses, $m_{chi}/He