Abstract
The observed values of the cosmological constant and the abundance of Dark Matter (DM) can be successfully understood, using certain measures, by imposing the anthropic requirement that density perturbations go non-linear and virialize to form halos. This requires a probability distribution favoring low amounts of DM, i.e. low values of the PQ scale f for the QCD axion and low values of the superpartner mass scale $$ \tilde{m} $$ for LSP thermal relics. In theories with independent scanning of multiple DM components, there is a high probability for DM to be dominated by a single component. For example, with independent scanning of f and $$ \tilde{m} $$ , TeV-scale LSP DM and an axion solution to the strong CP problem are unlikely to coexist. With thermal LSP DM, the scheme allows an understanding of a Little SUSY Hierarchy with multi-TeV superpartners. Alternatively, with axion DM, PQ breaking before (after) inflation leads to f typically below (below) the projected range of the current ADMX experiment of f = (3 − 30) × 1011 GeV, providing strong motivation to develop experimental techniques for probing lower f.
Highlights
Of inflating particles without any large scale structure or observers
In the Causal Patch measure [3], which removes the divergence by looking at finite regions around geodesics, the number of observers is diluted by inflation unless the time of Λ-domination occurs after the era at which observers occur, tΛ > tobs [4,5,6]
Another possibility is that the measure factor of eq (1.6) causes the probability distribution to peak at ξD ∼ ξB, explaining the observation that these matter components are broadly comparable [11]; this scheme is consistent with either single- or multi-component Dark Matter (DM)
Summary
Halo Virialization on comoving scale λ occurred when the matter density perturbation δm(λ) went non-linear. Varying ξD induces a variation in Te,Λ, the temperatures of matter-radiation and matter-Λ equality, as well as the timeboundaries involve close stellar encounters or disk fragmentation, and appear less robust than the requirement that density perturbations go non-linear Another possibility is that the measure factor of eq (1.6) causes the probability distribution to peak at ξD ∼ ξB, explaining the observation that these matter components are broadly comparable [11]; this scheme is consistent with either single- or multi-component DM. With good accuracy the nvir(Λ, ξD) factor depends only on the halo mass and the value of the matter density perturbation δm(tΛ) at the time of cosmological constant domination. We define this by extracting the exponential behavior of nΛmeas(Λ) from [5]: nΛmeas(Λ) ∝ e−3(Λ/Λobs)1/2
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