TH Cosmo Coffee

A Working Scenario for Relaxing the Cosmological Constant (note the unusual time !)

by Andrei Khmelnitsky (ICTP, Trieste)

Europe/Zurich
4/2-011 - TH common room (CERN)

4/2-011 - TH common room

CERN

15
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Description
We propose a technically natural and phenomenologically viable scenario whereby an initially large cosmological constant (c.c.) is relaxed down to the observed value due to the dynamics of a scalar evolving on a very shallow potential. The model crucially relies on a sector that violates the null energy condition (NEC) and gets activated only when the Hubble rate becomes sufficiently small — of the order of the present one. As a result of NEC violation, this low-energy universe evolves into inflation, followed by reheating and the standard Big Bang cosmology. Importantly, our model allows neither for eternal inflation and the current value of the c.c. is fixed by the parameters of the theory.