The cosmological constant problem and quintessence

  title={The cosmological constant problem and quintessence},
  author={Varun Sahni},
  journal={Classical and Quantum Gravity},
  • V. Sahni
  • Published 4 February 2002
  • Physics
  • Classical and Quantum Gravity
I briefly review the cosmological constant problem and the issue of dark energy (or quintessence). Within the framework of quantum field theory, the vacuum expectation value of the energy momentum tensor formally diverges as k4. A cutoff at the Planck or electroweak scale leads to a cosmological constant which is, respectively, 10123 or 1055 times larger than the observed value, Λ/8πG 10−47 GeV4. The absence of a fundamental symmetry which could set the value of Λ to either zero or a very small… 

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