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Relaxing a large cosmological constant (CROSBI ID 155275)

Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija

Bauer, Florian ; Sola, Joan ; Štefančić, Hrvoje Relaxing a large cosmological constant // Physics letters. B, 678 (2009), 5; 427-433. doi: 10.1016/j.physletb.2009.06.065

Podaci o odgovornosti

Bauer, Florian ; Sola, Joan ; Štefančić, Hrvoje

engleski

Relaxing a large cosmological constant

The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times. it has been rephrased as the dark energy (DE) problem in order to encompass a wider spectrum of possibilities. It is, in any case, a polyhedric puzzle with many faces, including the cosmic coincidence problem, i.e. why the density of matter rho(m) is presently so close to the CC density rho(Lambda). However, the oldest, toughest and most intriguing face of this polyhedron is the big CC problem, namely why the measured value of rho(Lambda) at present is so small as compared to any typical density scale existing in high energy physics, especially taking into account the many phase transitions that our Universe has undergone since the early times, including inflation. In this Letter, we propose to extend the field equations of General Relativity by including a class of invariant terms that automatically relax the value of the CC irrespective of the initial size of the vacuum energy in the early epochs. We show that, at late times, the Universe enters an eternal de Sitter stage mimicking a tiny positive cosmological constant. Thus, these models could be able to solve the big CC problem without fine-tuning and have also a bearing on the cosmic coincidence problem. Remarkably, they mimic the Lambda CDM model to a large extent, but they still leave some characteristic imprints that should be testable in the next generation of experiments.

Hubble-space-telescope ; equation-of-state ; dark energy ; modified gravity ; constraints ; parameters

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Podaci o izdanju

678 (5)

2009.

427-433

objavljeno

0370-2693

10.1016/j.physletb.2009.06.065

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Fizika

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