Minimal Supersymmetric Standard Model
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A Minimal Supersymmetric Standard Model is a class of proposed supersymmetric extensions to the Standard Model. Minimal supersymmetry assumes that the interaction between particles conserves R-parity and every particle has one superpartner.
Fermions have boson superpartners, and bosons have fermion superpartners. This removes problematic inconsistencies in Grand Unified theories.
| Particle type | Particle | Symbol | Spin | Superpartner | Symbol | Spin |
|---|---|---|---|---|---|---|
| Fermions | Quark | q | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | Squark | <math> \tilde{q} <math> | 0 |
| Neutrino | ν | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | Sneutrino | <math> \tilde{\nu} <math> | 0 | |
| Electron | e | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | Selectron | <math> \tilde{e} <math> | 0 | |
| Muon | μ | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | Smuon | <math> \tilde{\mu} <math> | 0 | |
| Tau | τ | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | Stau | <math> \tilde{\tau} <math> | 0 | |
| Bosons | W | W | 1 | Wino | <math> \tilde{W} <math> | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> |
| Z | Z | 1 | Zino | <math> \tilde{Z} <math> | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | |
| Photon | γ | 1 | Photino | <math> \tilde{\gamma} <math> | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | |
| Gluon | g | 1 | Gluino | <math> \tilde{g} <math> | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> | |
| Higgs bosons | Higgs | h, A, <math> H^0 <math>, <math> H^{+/-} <math> | 0 | Higgsinos | <math> \tilde{h}, \tilde{A}, \tilde{H^0}, \tilde{H^{+/-}} <math> | <math> \begin{matrix} \frac{1}{2} \end{matrix} <math> |
MSSM is an N=1 SUSY model in 3+1 Minkowski spacetime with <math>\frac{SU(3)\times SU(2) \times U(1)}{\mathbb{Z}_6}<math>. See SU(3)xSU(2)xU(1), supersymmetric gauge theory.
MSSM contains vector superfields associated with the gauge group. It also contains the following chiral superfields:
| field | multiplicity | representation | Z2-parity |
|---|---|---|---|
| q | 3 | <math>(3,2)_{1/6}<math> | - |
| uc | 3 | <math>(\bar{3},1)_{-2/3}<math> | - |
| dc | 3 | <math>(\bar{3},1)_{1/3}<math> | - |
| l | 3 | <math>(1,2)_{-1/2}<math> | - |
| ec | 3 | <math>(1,1)_1<math> | - |
| Hu | 1 | <math>(1,2)_{1/2}<math> | + |
| Hd | 1 | <math>(1,2)_{-1/2}<math> | + |
The electroweak symmetry is broken using the Higgs mechanism. There are also soft SUSY breaking terms in the action. Note that there is a PAIR of Higgs doublets. This is because MSSM forbids complex conjugation in the Yukawa potential.
The permissible (renormalizable and invariant) terms in the superpotential are HuHd, Huquc, Hdqdc and Hdlec. The constant term, of course, is unphysical.
Quad_cancellation.png
External Links
- Particle Data Group review of MSSM and search for MSSM predicted particles (http://pdg.lbl.gov/2004/listings/s046.pdf)