Abstract
In this paper, we study a non-canonical extension of a supergravity-motivated model acting as a vivid counterexample to the cosmic no-hair conjecture due to its unusual coupling between scalar and electromagnetic fields. In particular, a canonical scalar field is replaced by the string-inspired Dirac–Born–Infeld one in this extension. As a result, exact anisotropic inflationary solutions for this Dirac–Born–Infeld model are figured out under a constant-roll condition. Furthermore, numerical calculations are performed to verify that these anisotropic constant-roll solutions are indeed attractive during their inflationary phase.
Highlights
Cosmic inflation has played as one of the leading paradigms in modern cosmology [1,2,3,4]. This is due to the fact that many theoretical predictions of cosmic inflation have been well confirmed by the cosmic microwave background radiation (CMB) observations of the Wilkinson Microwave Anisotropy Probe (WMAP) [5] as well as the Planck [6,7,8] satellites
Some papers have appeared with an interesting idea that the mentioned anomalies could just be instrumental rather than cosmological [16,17,18]. The investigations in these papers have pointed out, using either the WMAP or Planck data, that the asymmetric beams could lead to the CMB statistical anisotropy
It is worth noting that a recent study has suggested that the Hubble tension might be a smoking gun for a breakdown of the Friedmann– Lemaitre–Robertson–Walker (FLRW) cosmology [20]
Summary
Cosmic inflation has played as one of the leading paradigms in modern cosmology [1,2,3,4]. [100,101,102,103,104,105,106] As a result, these noncanonical models have been shown to admit stable and attractive anisotropic power-law inflationary solutions, which do violate the validity of the cosmic no-hair conjecture [76,77,78,79,80]. It has been shown that the anisotropic constant-roll inflation is really attractive [81] All of these motivations lead us to propose to investigate in this paper whether the DBI extension of the KSW model [76] admits anisotropic constant-roll inflation.
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