Abstract
Supersymmetric models with radiatively-driven electroweak naturalness require light higgsinos of mass ∼ 100–300 GeV . Naturalness in the QCD sector is invoked via the Peccei-Quinn (PQ) axion leading to mixed axion-higgsino dark matter. The SUSY DFSZ axion model provides a solution to the SUSY μ problem and the Little Hierarchy μ≪ m3/2 may emerge as a consequence of a mismatch between PQ and hidden sector mass scales. The traditional gravitino problem is now augmented by the axino and saxion problems, since these latter particles can also contribute to overproduction of WIMPs or dark radiation, or violation of BBN constraints. We compute regions of the TR vs. m3/2 plane allowed by BBN, dark matter and dark radiation constraints for various PQ scale choices fa. These regions are compared to the values needed for thermal leptogenesis, non-thermal leptogenesis, oscillating sneutrino leptogenesis and Affleck-Dine leptogenesis. The latter three are allowed in wide regions of parameter space for PQ scale fa∼ 1010–1012 GeV which is also favored by naturalness: fa ∼ √μMP/λμ ∼ 1010–1012 GeV . These fa values correspond to axion masses somewhat above the projected ADMX search regions.
Highlights
1.1 Electroweak naturalnessThe recent discovery of the Higgs boson with mass mh 125 GeV at LHC8 [1, 2] brings with it a puzzle: why is the Higgs so light when its mass is quadratically divergent? Supersymmetry provides an elegant solution to this so-called naturalness problem by providing order-by-order cancellation of quadratic divergences
In a highly natural model where the electroweak sector is stabilized by SUSY, the QCD sector is stabilized by the axion, the μ problem is resolved by PQ-charged Higgs fields and the Little Hierarchy μ m3/2 emerges from radiative PQ breaking, one expects dark matter to be composed of an axion-higgsino admixture: i.e. two dark matter particles
In this paper we have investigated constraints on four compelling baryogenesis-via-leptogenesis scenarios within the framework of supersymmetric models with radiatively-driven naturalness
Summary
The recent discovery of the Higgs boson with mass mh 125 GeV at LHC8 [1, 2] brings with it a puzzle: why is the Higgs so light when its mass is quadratically divergent? Supersymmetry provides an elegant solution to this so-called naturalness problem by providing order-by-order cancellation of quadratic divergences. The somewhat large value of mh seems to require either well-mixed TeV scale top-squarks or 10-100 TeV top-squarks with small mixing [6, 7] These rather large sparticle mass values threaten to re-introduce the naturalness question: this time due to log divergences which emerge from the Little Hierarchy mweak msparticle ∼ 2 − 20 TeV. The electroweak fine-tuning measure ∆EW [9] compares the largest contribution on the right-hand-side of Eq 1.2 to the value of m2Z/2. The soft term m2Hu is driven radiatively to small values ∼ −(100 − 300) GeV2 at the weak scale (this is known as radiatively-driven naturalness or RNS). This can always occur in models with high scale Higgs soft term non-universality. A · m23/2 m2Hu(weak) so that a low value of ∆BG leads again to the same requirements as a low value of ∆EW
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