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Supersymmetry (SUSY)

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Supersymmetry(SUSY)

Jennifer Temple

December 1, 2005

QFT I

- Introduction
- Standard Model
- Motivations for SUSY
- History of SUSY

- Theory
- SUSY Experiments
- Conclusion

- Fermions:
- Quarks & leptons
- Half-integer unit spins (1/2, 3/2, …)

- Bosons:
- Force mediators
- Integer unit spins (0, 1, 2, …)

The gauge hierarchy problem

Characteristic energy of the SM: MW ~100 GeV

Characteristic energy scale of gravity: MP ~ 1019 GeV

Quantum gravity (?)

SUSY algebra contains generator of space-time translations

Quadratic divergence of the mass of scalar bosons

Arbitrary parameters in the SM

Electroweak symmetry breaking (EWSB) mechanism

- First mathematically consistent formulation was made in the 1970’s by several independent groups
- Part of superstring theory
- Current collider studies set limits on the masses of SUSY particles

Soft symmetry breaking

SUSY is broken in nature, this is why we don’t observe it everyday

This gives SUSY particles different masses

Minimal Supersymmetic Model

Electroweak symmetry breaking emerges naturally

Unification

R-Parity

- Supersymmetry is a symmetry that relates boson to fermion degrees of freedom.
- The generators of supersymmetry are two component anticommuting spinors, satisfying:

- Missing energy
- SUSY particles must be produced in pairs and all but the lightest SUSY (LSUSY) particle will quickly decay into other SUSY particles or SM particles
- LSUSY doesn’t interact with normal matter and so escapes the detector carrying off some energy

- Jets

- Supersymmetry is a symmetry that relates boson to fermion degrees of freedom. It provides the basis for an extension of the SM description of particle interactions.
- This is still an unproven theory and has a lot of opposition
- Future experiments:
- LHC @ CERN – 2007/8
- Linear Collider

- Haber, Howard E. and Kane, Gordon L., Is Nature Supersymmetric?
- Schwarz, John H., String Theory, Supersymmetry, Unification, and All That, Reviews of Modern Physics, Vol. 71, No. 2, The American Physical Society, 1999
- Tata, Xerxes, What is Supersymmetry and How Do We Find It?, 1997
- Wagner, Carlos, SUSY Lectures I & II, Fermilab, June 2005 (http://www-cdf.fnal.gov/physics/lectures/)
- Supersymmetry, Wikipedia