Abstract
We address the cosmological moduli/gravitino problems and the issue of too little thermal but excessive non-thermal dark matter from the decays of moduli. The main examples we study are the G2-MSSM models arising from M theory compactifications, which allow for a precise calculation of moduli decay rates and widths. We find that the late decaying moduli satisfy both BBN constraints and avoid the gravitino problem. The non-thermal production of Wino LSPs, which is a prediction of G2-MSSM models, gives a relic density of about the right order of magnitude.
Highlights
The existence of Dark Matter seems to require physics beyond the Standard Model
M theory compactifications on singular G2 manifolds are interesting in the sense that they give rise to N = 1 supersymmetry in four dimensions with non-Abelian gauge groups and chiral fermions
For the G2-MSSM model, we have found that light moduli and meson dominantly decay to light higgses and squarks, while the heavy modulus dominantly decay to light higgses only
Summary
The existence of Dark Matter seems to require physics beyond the Standard Model. If this physics arises from a string/M theory vacuum, one is faced with various problems associated with the moduli fields, which are gauge-singlet scalar fields that arise when compactifying string/M theory to four dimensions. The study of such vacua has proven to be technically challenging, much progress has been made towards understanding the effective four dimensional physics emerging from them [31,32,33,34] This includes many phenomenological implications of these vacua, in particular relating to issues such as constructing a realistic visible sector with chiral matter and non-abelian gauge bosons, supersymmetry breaking, moduli stabilization in a dS vacuum as well as explaining the Hierarchy between the Electroweak and Planck scales, as exemplified in a number of works [30, 35,36,37,38,39]. We present our main result, which is that the G2-MSSM naturally predicts a relic density of Wino-like neutralinos of about the right magnitude in agreement with observation This is followed by a detailed discussion of the results obtained and how it depends on the qualitative (and quantitative) features of the underlying physics.
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