Phantom fields have been widely invoked as a source of dark energy in cosmology, but rarely taken seriously as quantum theories. The vacuum is automatically unstable to production of negative-energy ghost particles plus normal particles, requiring such theories to be effective only, below some UV cutoff. The speaker will present recent cosmological constraints arising from the vacuum instability, both at the level of the homogeneous background, and the density perturbations. They find that the fluid of particles produced from vacuum decay can ameliorate but not solve the notorious Hubble tension problem, and cannot fully replace the cosmological constant as a source of dark energy. The vacuum decay can be a source of boosted dark radiation, which might be detectable if it interacts with ordinary matter. He will show that this could fit recent excess events reported by the DArk Matter In CCDs(DAMIC) experiment at Sudbury Neutrino Observatory LABoratory(SNOLAB).
頻道：Zoom ID:421-480-1692 ← cosmology
講者：James Cline (McGill University, Canada)
“Copernicus Webinar and Colloquium Series”: To promote scientific discussions during this pandemic, they are organizing an online seminar series, i.e. Copernicus Webinar Series, seeking the most outstanding speakers to introduce innovative ideas and important progress in the field of gravity and cosmology. This series is named after the famous Polish Astronomer, Nicolaus Copernicus, whose discovery eventually marked the dawn of modern science.