Direct dark matter searches—Test of the Big Bounce Cosmology

Abstract

We consider the possibility of using dark matter particle's mass and its interaction cross section as a smoking gun signal of the existence of a Big Bounce at the early stage in the evolution of our currently observed universe. A study of dark matter production in the pre-bounce contraction and the post bounce expansion epochs of this universe reveals a new venue for achieving the observed relic abundance of our present universe. Specifically, it predicts a characteristic relation governing a dark matter mass and interaction cross section and a factor of 1/2 in thermally averaged cross section, as compared to the non-thermal production in standard cosmology, is needed for creating enough dark matter particle to satisfy the currently observed relic abundance because dark matter is being created during the pre-bounce contraction, in addition to the post-bounce expansion. As the production rate is lower than the Hubble expansion rate information of the bounce universe evolution is preserved. Therefore once the value of dark matter mass and interaction cross section are obtained by direct detection in laboratories, this alternative route becomes a signature prediction of the bounce universe scenario. This leads us to consider a scalar dark matter candidate, which if it is light, has important implications on dark matter searches.

Big Bounce Genesis and Possible Experimental Tests: A Brief Review

“…Therefore one can be hopeful that data from current and future DM detections can tell these two early universe scenarios apart [61]. A confirmed relation between DM mass and the interaction cross-section not only can lend support to the idea that the cosmos goes through a bounce and not a bang, but also establishes the one-way production of matter in the early universe.…”

“…This relation of cross-section and mass is shown as Branch B in Figure 2. As a smoking gun signal for the existence of the bounce universe, this novel relation can be used to check against recent and near future data from experiments of DM to determine whether or not the universe undergoes a big bounce at a very early stage of cosmic evolution [61,64]. In general, the production and evolution of DM in the bounce cosmos (Big Bounce Genesis for short) brings about new possibilities, compared to the standard model particle physics in the standard cosmology, which are listed in Table 2.…”

“…We study the generation of thermal fluctuations of DM in the bounce cosmos following [65] and show that the bounce dynamic is stable against thermal fluctuations for T bounce ≤ T Planck , in Section 3. In Section 4, we discuss the search of BBG DM in direct detection experiments for mass range DM mass ∼ 100 GeV using nuclear recoil [61] and for light DM by electron recoil [64].…”

“…where the last two ingredients have been discussed extensively in [61], but we are not going to discuss these two ingredients in this work further.…”

“…For the purpose of comparing the predictions of BBG with direct DM search [85][86][87][88][89][90][91][92][93][94][95][96], we focus on the study of the DM-nucleon cross-section in this section following [61,64].…”