Relic Density of Asymmetric Dark Matter in Modified Cosmological Scenarios

Abstract

We discuss the relic abundance of asymmetric Dark Matter particles in modified cosmological scenarios where the Hubble rate is changed with respect to the standard cosmological scenario. The modified Hubble rate leaves its imprint on the relic abundance of asymmetric Dark Matter particles if the asymmetric Dark Matter particles freeze-out in this era. For generality we parameterize the modification of the Hubble rate and then calculate the relic abundance of asymmetric Dark Matter particles and anti-particles.We found the abundances for the Dark Matter particles and anti-particles are enhanced in the modified cosmological models. The indirect detection signal is possible for the asymmetric Dark Matter particles due to the increased annihilation rate in the modified cosmological models. Applying Planck data, we find the constraints on the parameters of the modified cosmological models.

Leptogenesis in fast expanding Universe

“…It was shown in [35] that presence of a scalar field ϕ can result in a fast expanding Universe, and therefore affects the thermal freeze-out relics of dark matter. Similar studies with the fast expanding Universe were performed for the case of freeze-in dark matter [43,44], keV neutrino dark matter [45,46], asymmetric dark matter models [47]- [51] and sterile neutrinos [52,53]. Study of leptogenesis was performed earlier with different cosmological scenarios of the Universe such as including dark matter [54] or scalar tensor gravity [55].…”

Consequences of f(?) Cosmology in Thermal Leptogenesis and Gravitino Late Abundance

“…However, if the Universe evolution is described by a non standard cosmology, then the expansion rate is replaced by (1). This implies that the factor Θ GR in (13) is replaced by Θ GR → Θ = Θ GR /A(T) [45,56,57]. In such a circumstance, the reheating temperature T R entering the above expression for Y 3/2 is replaced by the transition temperature T * .…”

Dark matter freeze-out in modified cosmological scenarios

“…3 The parameters that we are interested in varying are the mass of the Dark Matter (m), the value of η, and the thermally averaged cross section σ 0 , as well as investigating the cases of n D = 6, 8. The n D = 6 scenario corresponds to some quintessence models with a kination phase while the n D = 8 corresponds to brane world cosmology or some late inflaton decay models [36]. We are not interested in changing x 0 because any such change can be absorbed into a change in η.…”

“…There has also been work on early matter dominated eras which decay away [27][28][29][30]. All these models have a different expansion rate from the standard Λ CMD model and some previous work has been done to understand the physics in these scenarios [9][10][11]36].…”

“…For the case of asymmetric Dark Matter, one must include nonzero chemical potentials in the exponential. See[7,36] for details 2. It is typical to choose the mass scale in the definition of x to be…”