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Constrained Minimal Supersymmetric Standard Model. Focus Point for WIMP Searches. Review of Standard Model. Supersymmetry (SUSY) . Symmetry in Lagrangian between fermions and bosons Each standard model particle has a supersymmetric partner
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Constrained Minimal Supersymmetric Standard Model Focus Point for WIMP Searches
Supersymmetry (SUSY) • Symmetry in Lagrangian between fermions and bosons • Each standard model particle has a supersymmetric partner • Superpartners differ by half integer spin but share all other quantum numbers • Partner of electron is selectron (scalar electron) • Partner of photon is photino
SUSY is a Broken Symmetry • No Superpartners have been detected • Masses must not be the same • This happens if SUSY is a broken symmetry
SUSY and Dark Matter • Superpartners should exist in early universe • Exist in equilibrium (created and annihilated at same rate) • Lightest SUSY particle should be stable (assuming R-Parity) • As universe expands, a thermal relic density freezes out • Relic particles constitute Dark Matter
Minimal Supersymmetric Standard Model (MSSM) • Use minimum number of superpartners • Reduces the number of SUSY parameters • m0 • m1/2 • A0 • tan β • Sign of μ
Constrained MSSM (CMSSM) • Use constraints from experiments to find most likely values for MSSM parameters • Monte Carlo performed to determine which regions of parameter space best fit current experimental data • Branching Ratio for B mesons to Strange mesons • Top quark mass
Sign of μ • New value of B meson to Strange meson Branching Ratio • μ > 0 is preferred, but not ruled out • ~ 10% relative probability for μ < 0
Conclusions • CMSSM provides well defined region of phase space to look for WIMP Dark Matter • Assuming MSSM, plus current experimental constraints • Determines Focus Point Region for Direct Detection Experiments • Next generation Dark Matter searches should probe this region of phase space
Remaining Questions • How to get MSSM parameters from Supersymmetric Lagrangian • How to calculate cross-section and mass from SUSY parameters • How to determine constraints on SUSY parameters from current measurements • Difference between SI and SD interactions and how to set limit for each