The case for the cosmological constant

[摘要] I present a short overview of current observational results and theoretical models for a cosmological constant. The main motivation for invoking a small cosmological constant (or 𝛬-term) at the present epoch has to do with observations of high redshift Type Ia supernovae which suggest an accelerating universe. A flat accelerating universe is strongly favoured by combining supernovae observations with observations of CMB anisotropies on degree scales which give the `best-fit’ values 𝛺𝛬 ≃ 0.7 and 𝛺m ≃ 0.3. A time dependent cosmological 𝛬-term can be generated by scalar field models with exponential and power law potentials. Some of these models can alleviate the `fine tuning’ problem which faces the cosmological constant.

[学科分类] 物理（综合）

[关键词] Cosmology;supernovae;cosmic microwave background;cosmological constant;vacuum fluctuations.