Late-time Cosmology without Dark Sector but with Closed String Massless Sector

by Mr Hocheol Lee (CQUeST, Seoul and Sogang U.)

Thursday 29 Feb 2024, 16:00 → 17:30 Asia/Seoul

Room 1423 (KIAS)

Title: Late-time Cosmology without Dark Sector but with Closed String Massless Sector

Speaker: Mr. Hocheol Lee (CQUeST, Seoul and Sogang U.)

Abstract: We address the dark energy and the coincidence problems by postulating the massless sector of closed strings. This sector constitutes the gravitational multiplet of string theory and, when applied to four-dimensional cosmology, predicts that the expansion of an open Universe defined in string frame is readily accelerating. We confront the prediction with the late-time cosmological data of Type Ia supernovae and quasar absorption spectrum, which probe the evolutions of the Hubble parameter and possibly the fine-structure constant. We report that these observations are in admirable agreement with the prediction without any dark sector and coincidence problem. We estimate the Hubble constant, 71.2 km/s/Mpc.