2024/10/17 by Parra, Nicolás, Sypsas, Spyros, Palma, Gonzalo A. +1
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th)
paper · doi:10.48550/arxiv.2410.13843
Particle production in de Sitter spacetime arises from the exponential expansion of space, rendering the Bunch-Davies vacuum perceived as a particle-containing state by late-time observers. For states defined as eigenstates of both momentum and the Hamiltonian, the Bunch-Davies vacuum exhibits a constant particle density per physical momentum. We explore particle production beyond this baseline, focusing on deviations from exact de Sitter conditions and non-gravitational interactions, such as slow-roll inflation or interactions arising from the coupling of inflation to other fields. Using Bogoliubov transformations, we calculate the number density of energy/momentum eigenstates. In single-field inflation, this density captures the observed spectral index of the primordial power spectrum, while in two-field models, it reflects the non-gravitational coupling driving background trajectory turning. We present analytical results applicable to various scenarios involving particle production from non-adiabatic processes during inflation.