http://arxiv.org/abs/1404.1570
A canonical pseudo-Nambu Goldstone Boson (pNGB) can play the role of a dark energy field responsible for present cosmic acceleration. Confronting with the recent cosmological data, we find that the pNGB field requires spontaneous symmetry breaking scale f close to M_P and the initial field value fine-tuned. It is difficult to achieve a large f in a theoretically consistent set-up. A possible resolution can be achieved by increasing the Hubble friction in well motivated particle physics models in the general set-up of modified gravity theories. We show two examples of this set-up and confront those with the recent supernovae, PLANCK and BAO data. We find that moderate values of the dimensionless constants that increase the friction, make f << M_{P} and the generic initial conditions also favorable by the data.
D. Adak and K. Dutta
Tue, 8 Apr 14
7/71
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