Abstract
The Minimal Supersymmetric Standard Model (MSSM) is under intense scrutiny at the LHC and in dark matter searches. Interestingly, scenarios with light squarks of the third generation remain not only viable, but also well motivated by the observed Standard-Model-like Higgs boson mass and dark matter relic density. The latter often requires important contributions from squark pair annihilation. Following up on previous work, we present in this paper a precision analysis of squark pair annihilation into quarks at next-to-leading order of QCD including Sommerfeld enhancement effects. We discuss all technical details of our one-loop, real emission and resummation calculations, their implementation in the precision tool DM@NLO, as well as the numerical impact on the annihilation cross section and cosmological relic density in phenomenological MSSM scenarios respecting in particular current LHC constraints. We demonstrate that including these radiative corrections leads to substantial shifts in the preferred parameter regions by up to 20 GeV.
Highlights
Strong evidence for the existence of dark matter, along with the fact that neutrinos are massive, is a compelling sign of the need for physics beyond the Standard Model
As we move along the region with the correct relic density towards scenarios with heavier lightest supersymmetric particle (LSP) and next-to-lightest supersymmetric particle (NLSP), we reach a point where the LSP and NLSP are similar in mass to the light gluino
For even larger masses the region where the relic density is compatible with the Planck measurement features a stop LSP, such that neutralino dark matter would be excluded for M1 ≳ 1800 GeV
Summary
Strong evidence for the existence of dark matter, along with the fact that neutrinos are massive, is a compelling sign of the need for physics beyond the Standard Model. The relic density of dark matter in scenarios with a light stop which is almost mass degenerate with the lightest neutralino is very sensitive to the mass difference of the two particles. Any small shift in the predicted relic density can cause a large shift of the parameter region where the relic density is compatible with the experimental limits given by Eq (1.1) In this analysis we focus on next-to-leading supersymmetric QCD (SUSY-QCD) corrections to the corresponding annihilation and co-annihilation cross sections in scenarios with a light scalar quark. The theoretical uncertainty from scale and scheme variations on the annihilation cross section and the neutralino relic density has been evaluated for specific subclasses of processes in Ref.
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