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# Minimal Supersymmetric Standard Model

(Redirected from MSSM)

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 $\begin{matrix} \frac{1}{2} \end{matrix}$ Squark $\tilde{q}$ 0
Neutrino ν $\begin{matrix} \frac{1}{2} \end{matrix}$ Sneutrino $\tilde{\nu}$ 0
Electron e $\begin{matrix} \frac{1}{2} \end{matrix}$ Selectron $\tilde{e}$ 0
Muon μ $\begin{matrix} \frac{1}{2} \end{matrix}$ Smuon $\tilde{\mu}$ 0
Tau τ $\begin{matrix} \frac{1}{2} \end{matrix}$ Stau $\tilde{\tau}$ 0
Bosons W W 1 Wino $\tilde{W}$ $\begin{matrix} \frac{1}{2} \end{matrix}$
Z Z 1 Zino $\tilde{Z}$ $\begin{matrix} \frac{1}{2} \end{matrix}$
Photon γ 1 Photino $\tilde{\gamma}$ $\begin{matrix} \frac{1}{2} \end{matrix}$
Gluon g 1 Gluino $\tilde{g}$ $\begin{matrix} \frac{1}{2} \end{matrix}$
Higgs bosons Higgs h, A, H0, H + / - 0 Higgsinos $\tilde{h}, \tilde{A}, \tilde{H^0}, \tilde{H^{+/-}}$ $\begin{matrix} \frac{1}{2} \end{matrix}$

MSSM is an N=1 SUSY model in 3+1 Minkowski spacetime with $\frac{SU(3)\times SU(2) \times U(1)}{\mathbb{Z}_6}$. 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 :

fieldmultiplicityrepresentationZ2-parity
q3(3,2)1 / 6-
uc3$(\bar{3},1)_{-2/3}$-
dc3$(\bar{3},1)_{1/3}$-
l3(1,2) - 1 / 2-
ec3(1,1)1-
Hu1(1,2)1 / 2+
Hd1(1,2) - 1 / 2+

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.

Last updated: 05-12-2005 17:42:48
03-10-2013 05:06:04