Theoretical High Energy Seminar – University of Copenhagen

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Theoretical High Energy Seminar

Speaker: Maxim Perlstein

Title:  Dark Matter Searches and Fine-Tuning in Supersymmetry

Abstract:  I will discuss the implications of recent direct dark matter searches within
the minimal supersymmetric standard model (MSSM). Assuming that no
accidental cancellations occur in the spin-independent elastic
neutralino-quark scattering cross section, I will argue that direct
detection cross section below 10^-44 cm^2 requires the lightest
supersymmetric particle (LSP) neutralino to be close to either a pure
gaugino or pure Higgsino limit, with smaller cross sections correlated with
smaller admixture of the subdominant components. The current XENON100 bound
rules out essentially all models in which the lightest neutralino has the
Higgsino fraction between 0.2 and 0.8. Furthermore, smaller direct detection
cross sections correlate with stronger fine-tuning in the electroweak
symmetry breaking sector. The current XENON100 bound already implies some
fine-tuning: for example, at least 10% tuning is required if the LSP mass is
above 70 GeV.