Mirage in the sky: Nonthermal dark matter, gravitino problem, and cosmic ray anomalies

Abstract

Recent anomalies in cosmic rays could be due to dark matter annihilation in our galaxy. In order to get the required large cross-section to explain the data while still obtaining the right relic density, we rely on a non standard thermal history between dark matter freeze-out and Big-Bang Nucleosynthesis (BBN). We show that through a reheating phase from the decay of a heavy moduli or even the gravitino, we can produce the right relic density of dark matter if its self-annihilation crosssection is large enough. In addition to fitting the recent data, this scenario solves the cosmological moduli and gravitino problems. We illustrate this mechanism with a specific example in the context of U (1)B−L extended MSSM where supersymmetry is broken via mirage mediation. These string motivated models naturally contain heavy moduli decaying to the gravitino, whose subsequent decay to the LSP can reheat the universe at a low temperature. The right-handed sneutrino and the B − L gaugino can both be viable dark matter candidates with large cross-section. They are leptophilic because of B − L charges. We also show that it is possible to distinguish the non-thermal from the thermal scenario (using Sommerfeld enhancement) in direct detection experiments for certain regions of parameter space.

Non-thermal CMSSM with a 125 GeV Higgs

“…There are more green points for T R = 10 GeV since the annihilation cross section becomes smaller due to Bino mixing which means a larger allowed region after using Fermi data but the constraint from the direct detection becomes more stringent (due to Bino-Higgsino mixing in the LSP) and JHEP05(2015)098 so there are no red points which saturate the observed DM content. 6 For the points shown in figure 6, the GUT values c = B/M and d = µ/M are around 0.6 and 1 respectively.…”

“…There is therefore no reason to assume a very simple cosmological history characterised by just a single period of radiation dominance from the end of inflation until BBN. In fact, the presence of a period of matter domination between the end of inflation and BBN could completely change the final prediction for the DM relic density if the reheating temperature at the end of this period of matter dominance is below T f [1][2][3][4][5][6].…”

“…The abundance of DM particles χ produced non-thermally by the decay of the lightest modulus is given by [3][4][5][6]:…”

Affleck-Dine baryogenesis in effective supergravity

“…The late decay of gravitationally coupled moduli leads to various modifications of standard cosmological scenarios such as the non-thermal production of dark matter [7], [8] and baryogenesis [9]. In the early universe the moduli are displaced from the minimum of their potential and start oscillating.…”

Supersymmetry, nonthermal dark matter, and precision cosmology

“…Dark matter models are constrained by both direct detection experiments and searches for astrophysical signals generated by their annihilation products. Nonthermal dark matter can have a higher self interaction cross-section than thermal dark matter so astrophysical signals are potentially stronger for these scenarios, particularly in indirect experiments such as FERMI and AMS-2 [20][21][22][23][24][25].…”