Varying alpha generalized DiracBornInfeld models
Abstract
We study the cosmological consequences of a class of DiracBornInfeld models, and assess their viability as a candidate for the recent acceleration of the Universe. The model includes both the rolling tachyon field and the generalized Chaplygin gas models as particular limits, and phenomenologically each of these provides a possible mechanism for a deviation of the value of the dark energy equation of state from its canonical (cosmological constant) value. The fielddependent potential that is characteristic of the rolling tachyon also leads to variations of the finestructure constant α , implying that the model can be constrained both by standard cosmological probes and by astrophysical measurements of α . Our analysis, using the latest available lowredshfit data and local constraints from atomic clock and weak equivalence principle experiments, shows that the two possible deviations of the dark energy equation of state are constrained to be log_{10}(1 +w_{0})_{V} <7.85 and log_{10}(1 +w_{0})_{C} <0.85 , respectively for the rolling tachyon and Chaplygin components, both being at the 95.4% confidence level (although the latter depends on the choice of priors, in a way that we quantify). Alternatively, the 95.4% confidence level bound on the dimensionless slope of the potential is log_{10}λ <5.36 . This confirms previous analyses indicating that in these models the potential needs to be extremely flat.
 Publication:

Physical Review D
 Pub Date:
 January 2021
 DOI:
 10.1103/PhysRevD.103.023525
 arXiv:
 arXiv:2101.08584
 Bibcode:
 2021PhRvD.103b3525T
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology
 EPrint:
 15 pages, 6 figures