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Summary: Volume 150B, number 6 PHYSICS LETTERS 24 January 1985
A MECHANISM FOR REDUCING THE VALUE OF THE COSMOLOGICAL CONSTANT
L.F. ABBOTT 1
PhysicsDepartment, Brandeis University, Waltham,MA 02254, USA
Received 30 October 1984
A mechanism is presented for relaxing an initiallylarge, positive cosmological constant to a value near zero. This is done
by introducing a scalar field whose vacuum energy compensates for the initial cosmologicalconstant. The compensating sec-
tor involves small mass scales but no unnatural fine-tuning of parameters. It is not clear how to incorporate this mechanism
into a realistic cosmology.
The extremely small observational limits on the val-
ue of the cosmological constant indicate that the vacu-
um energy density in our universe has magnitude less
than (0.003 eV)4. The vacuum energy density receives
contributions proportional to the fourth power of vir-
tually every mass scale in particle physics. Since each
of these terms individually is many orders of magni-
tude larger than (0.003 eV)4, mysterious and unnatu-
ral cancellations must occur in order for their sum to
produce a sufficiently small total energy density. This
situation is very different from that of a naturally
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