Abstract
Explicit string models which can realize inflation and low-energy supersymmetry are notoriously difficult to achieve. Given that sequestering requires very specific configurations, supersymmetric particles are in general expected to be very heavy implying that the neutralino dark matter should be overproduced in a standard thermal history. However, in this paper we point out that this is generically not the case since early matter domination driven by string moduli can dilute the dark matter abundance down to the observed value. We argue that generic features of string compactifications, namely a high supersymmetry breaking scale and late time epochs of modulus domination, might imply superheavy neutralino dark matter with mass around 1010–1011 GeV. Interestingly, this is the right range to explain the recent detection of ultra-high-energy neutrinos by IceCube and ANITA via dark matter decay.
Highlights
Scrutiny by recent experiments, namely the Fermi-LAT results from observations of dwarf spheroidal galaxies [2] and newly discovered Milky Way satellites [3]
We argue that generic features of string compactifications, namely a high supersymmetry breaking scale and late time epochs of modulus domination, might imply superheavy neutralino dark matter with mass around 1010–1011 GeV
Non-thermal production of supersymmetric DM via the branching scenario has been studied in explicit string theory constructions where the volume modulus drives an epoch of early matter domination (EMD) just before the onset of Big Bang nucleosynthesis (BBN) [13]
Summary
The comoving number density of DM follows this expression, the name ‘branching scenario’ [11, 12], provided that residual annihilation of DM particles to the thermal bath is inefficient. This will be the case if σannv nχ < Γφ, where nχ is substituted from (2.2). A natural question is if the branching scenario can be successfully realized in explicit particle physics models of the early universe This issue has been discussed in the context of type IIB string compactifications where φ is the volume modulus [13]. Avoiding excessive production of DR, which typically accompanies DM production in string compactifications [30,31,32,33], seems to favor the annihilation scenario [14]
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