State of the Universe

Do cosmological observations allow a negative Λ?

by Prof. Anjan Sen (Jamia Milia Islamia, Delhi)

Friday, September 23, 2022 from to (Asia/Kolkata)
at A304 and Zoom: Meeting ID: 825 1295 6967 Passcode: 384194
In view of the recent measurement of H0 from HST and SH0ES team, we explore the possibility of existence of a negative cosmological constant in the Universe. In this regard, we consider quintessence fields on top of a negative cosmological constant and compare such construction with Λ CDM model using different combination of CMB, SnIa, BAO and H0 data. Various model comparison estimators show that quintessence models with a negative Λ is either preferred over Λ CDM or performs equally well as Λ CDM model. This suggests that the presence of a negative Λ (AdS ground state) in our Universe, which can naturally arise in string theory, is consistent with cosmological observations.