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Minimal Supersymmetric Standard Model (MSSM)

Minimal Supersymmetric Standard Model (MSSM). SUSY: # of fermions = # of bosons. N=1 SUSY:. SM: 28 bosonic d.o.f. & 90 (96) fermionic d.o.f. There are no particles in the SM that can be superpartners. SUSY associates known bosons with new fermions and known fermions with new bosons.

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Minimal Supersymmetric Standard Model (MSSM)

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  1. Minimal Supersymmetric Standard Model (MSSM) SUSY: # of fermions = # of bosons N=1 SUSY: SM: 28 bosonic d.o.f. & 90 (96) fermionic d.o.f. There are no particles in the SM that can be superpartners SUSY associates known bosons with new fermions and known fermions with new bosons Even number of the Higgs doublets – min = 2 Cancellation of axial anomalies (in each generation) Higgsinos -1+1=0

  2. Particle Content of the MSSM sleptons leptons squarks quarks higgsinos{ Higgses {

  3. The MSSM Lagrangian The Yukawa Superpotential Superfields Yukawa couplings Higgs mixing term Violate: Lepton number Baryon number These terms are forbidden in the SM

  4. R-parity B - Baryon Number L - Lepton Number S - Spin The Usual Particle : R = + 1 SUSY Particle : R = - 1 The consequences: • The superpartners are created in pairs • The lightest superparticle is stable • The lightest superparticle (LSP) should be neutral - the best candidate is neutralino (photino or higgsino) • It can survive from the Big Bang and form the Dark matter in the Universe

  5. Interactions in the MSSM MSSM SM Vertices

  6. Creation of Superpartners at colliders Annihilation channel Gluon fusion, ee, qq scattering and qg scattering channels

  7. Decay of Superpartners squarks sleptons neutralino Final sates chargino gluino

  8. Spontaneous Breaking of SUSY Energy if and only if

  9. Soft SUSY Breaking Hidden sector MSSM SUSY Messengers Gravitons, gauge, gauginos, etc Breaking via F and D terms in a hidden sector gauginos scalar fields Over 100 of free parameters !

  10. Soft SUSY Breaking SUGRA S-dilaton, T-moduli gravitino mass Gauge mediation Scalar singlet S Messenger Φ gravitino mass gaugino squark

  11. MSSM Parameter Space • Three gauge couplings • Three (four) Yukawa matrices • The Higgs mixing parameter • Soft SUSY breaking terms mSUGRA Universality hypothesis (gravity is colour and flavour blind): Soft parameters are equal at Planck (GUT) scale Five universal soft parameters: in the SM versus and

  12. Mass Spectrum Chargino Neutralino

  13. Mass Spectrum Squarks & Sleptons

  14. SUSY Higgs Bosons SM 4=2+2=3+1 MSSM 8=4+4=3+5

  15. The Higgs Potential Minimization Solution At the GUT scale No SSB in SUSY theory !

  16. Higgs Boson’s Masses

  17. The Higgs Bosons Masses CP-odd neutral Higgs A CP-even charged Higgses H CP-even neutral Higgses h,H Radiative corrections

  18. Renormalization Group Eqns The Couplings Soft terms

  19. RG Eqns for the Soft Masses

  20. Radiative EW Symmetry Breaking Due to RG controlled running of the mass terms from the Higgs potential they may change sign and trigger the appearance of non-trivial minimum leading to spontaneous breaking of EW symmetry - this is called Radiative EWSB

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