Neutralino versus axion/axino cold dark matter in the 19 parameter SUGRA model

Abstract

We calculate the relic abundance of thermally produced neutralino cold dark matter in the general 19 parameter supergravity (SUGRA-19) model. A scan over GUT scale parameters reveals that models with a bino-like neutralino typically give rise to a dark matter density Ωχ0 1 h 2 ∼ 1 − 1000, i.e. between 1 and 4 orders of magnitude higher than the measured value. Models with higgsino or wino cold dark matter can yield the correct relic density, but mainly for neutralino masses around 700-1300 GeV. Models with mixed bino-wino or bino-higgsino CDM, or models with dominant co-annihilation or A-resonance annihilation can yield the correct abundance, but such cases are extremely hard to generate using a general scan over GUT scale parameters; this is indicative of high fine-tuning of the relic abundance in these cases. Requiring that mχ0 1 < ∼ 500 GeV (as a rough naturalness requirement) gives rise to a minimal probably dip in parameter space at the measured CDM abundance. For comparison, we also scan over mSUGRA space with four free parameters. Finally, we investigate the Peccei-Quinn augmented MSSM with mixed axion/axino cold dark matter. In this case, the relic abundance agrees more naturally with the measured value. In light of our cumulative results, we conclude that future axion searches should probe much more broadly in axion mass, and deeper into the axion coupling.

Supersymmetric dark matter in the harsh light of the Large Hadron Collider

“…9, from ref. 29. The most easily obtained values of the dark matter density are an order of magnitude either higher or lower than the observed value.…”

Axino cold dark matter revisited

“…For the abelian U(1) Y factor, the processes A, B, and F vanish and we can replace |T a jk | 2 with the square of the corresponding hypercharges. Finally, we use N F = (12,14,11) to count the matter multiplets charged under the MSSM gauge groups (SU(3), SU(2) L and U(1) Y ), respectively. We include above the SUSY breaking scale the full 1-loop MSSM running of the gauge couplings and gaugino masses.…”

“…[1,2]. The scenario was subsequently extensively studied during the last decade [3][4][5][6][7][8][9][10][11][12][13][14][15][16], with either a neutralino or a stau as the next-to-lightest supersymmetric particle (NLSP). Ways of testing the axino CDM scenario at the LHC were explored in refs.…”

Nonminimal chaotic inflation, Peccei-Quinn phase transition, and nonthermal leptogenesis

“…As a consequence of its relatively large decay temperature, the LSPs produced by the saxion decay are likely to be thermalized and therefore, no upper bound on the saxion abundance is [41] to be imposed. Finally, if axino is sufficiently light it can act as a CDM candidate [18,19] with relic abundance produced predominantly thermally -due to the relatively large T rh . Otherwise, it may enhance [19] non-thermally the abundance of a higgsino-like neutralino-LSP, rendering it a successful CDM candidate.…”

“…Note that there is an increasing interest [18,19] in such models at present, since they provide us with two additional cold dark matter (CDM) candidates (axino and axion) beyond the lightest neutralino. In our model, a PQ phase transition (PQPT), tied on renormalizable [11,20] .…”