Asymmetric dark matter and the scalar-tensor model

Abstract

The relic abundance of asymmetric Dark Matter particles in the scalar-tensor model is analyzed in this article. We extend the numeric and analytic calculation of the relic density of the asymmetric Dark Matter in the standard cosmological scenario to the nonstandard cosmological scenario. We focus on the scalar-tensor model. Hubble expansion rate is changed in the nonstandard cosmological scenario. This leaves its imprint on the relic density of Dark Matter particles. In this article we investigate to what extent the asymmetric Dark Matter particle's relic density is changed in the scalar-tensor model.We use the observed present day Dark Matter abundance to find the constraints on the parameter space in this model. *

Dark matter relic density in scalar-tensor gravity revisited

“…However these studies are based upon the enhancement factor (1.2) and also neglect the temperature dependence of g * (T ). Unsurprisingly, our results are much less dramatic than those given by Gelmini et al [9] and Wang et al [30] who found that the required annihilation cross section can be increased by several orders of magnitude.…”

“…To complete our study we also investigated the relic abundance of asymmetric dark matter species in scalar-tensor gravity models and found that the required annihilation cross section was enhanced only slightly, in contrast to the several order of magnitude estimates given in Gelmini et al [9] and Wang et al [30] who both used the parameterization (1.2) given in Catena et al [28].…”

“…Despite this secondary annihilation phase, they showed that the relic abundance of dark matter in scalar-tensor gravity models can still be enhanced by up to three orders of magnitude (depending on the WIMP mass m χ ). The approximate form (1.2) of the ratio H ST /H GR has since been adopted in several subsequent investigations, including those by Gelmini et al [9], Rehagen and Gelmini [29] and, very recently, Wang et al [30] who studied the relic abundance of asymmetric dark matter species [9,30] and sterile neutrinos [29], and naturally obtained similarly large enhancement factors for the dark matter relic abundance. Subsequently Catena et al [5] considered the coupling A(ϕ * ) = 1 + bϕ 2 * as part of a more general study of dark matter relic abundances in non-standard cosmological scenarios and once again found that the relic abundance in scalar-tensor cosmology is enhanced by several orders of magnitude.…”

Abundance of Asymmetric Dark Matter in Brane World Cosmology

“…Usually the indirect detection is not available for the asymmetric Dark Matter. However, for asymmetric Dark Matter in nonstandard cosmological scenarios including quintessence, scalar-tensor model and brane world cosmology [9,10,11], the relic densities for both particle and antiparticle are increased in due to the enhanced Hubble expansion rate. Again for appropriate cross section, the relic density for both particle and anti-particle are almost in the same amount which is different from the standard cosmological scenario where the anti-particle relic density is depressed .…”

“…The modified Hubble expansion rate affects the relic density of asymmetric Dark Matter. The asymmetric Dark Matter relic density is already investigated in such models including quintessence model, scalar-tensor model [9,10,11]. In quintessence model, scalar-tensor models, the relic densities of both particles and anti-particles are increased simultaneously due to the increased Hubble expansion rate.…”