Muhammad Bilal Azam, Maqbool Ahmed
Session: Poster Presentation Session of SBASSE Graduate Students with the School’s Advisory Board (2020)
Institution: Department of Physics, Lahore University of Management Sciences

Cosmological constant (Λ) is one of the expected candidates for dark energy. However, it also raises a fundamental question that why “only now” cosmological constant is of the order of ambient density? Answer comes from the unimodular gravity which predicts the fluctuations in Λ and causal set theory predicts the magnitude of these fluctuations. For closed universe, the ansatz [1] provides a Λ, which fluctuates about zero, and is comparable to the ambient energy density at all times.

[1] Ahmed, M., Dodelson, S., Greene, P. B., and Sorkin, R. (2004). Everpresent Λ. Phys. Rev. D, 69:103523

DOI: 10.13140/RG.2.2.30779.36641

PDF (Download Link)

Everpresent Lambda in Closed Universe (Poster)