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Encyclopedia > Minimal Supersymmetric Standard Model

The Minimal Supersymmetric Standard Model (MSSM) is the minimal extension to the Standard Model that realizes supersymmetry (non-minimal extensions exist). Supersymmetry pairs bosons with fermions, therefore every Standard Model particle has a partner that has yet to be discovered. The MSSM was originally proposed 1981 to stabilize the weak scale, solving the hierarchy problem. The Higgs mass of the Standard Model is unstable to quantum corrections and the theory predicts that weak scale should much at a very high energy. In the MSSM, the Higgs has a fermionic superpartner, called the Higgsino, that it would have the same mass as itself if supersymmetry was an exact symmetry. Because fermion masses are radiatively stable, the Higgs mass inherits this stability. The Standard Model of Fundamental Particles and Interactions The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In theoretical physics, a hierarchy problem is a confusing observation that two fundamental quantities with the same units have vastly different values, and therefore the naïve calculation based on dimensional analysis can lead to incorrect results. ...

Currently the Tevatron is the highest energy particle collider and is activley looking for evidence of the production of supersymmetric particles. Most physicists believe that supersymmetry must be discovered at the LHC if it is responsible for stabilizing the weak scale. There are five classes of particle that superpartners of the Standard Model fall into: squarks, gluinos, charginos, neutralinos, and sleptons. Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... For the pop group, see Les Horribles Cernettes Construction of the CMS detector for LHC at CERN The Large Hadron Collider (short LHC) is a particle accelerator and collider located at CERN. It is currently under construction and scheduled to start operation in 2007. ... In particle physics, a squark is a hypothetical boson partner of a quark whose existence is implied by supersymmetry. ... A gluino is a subatomic particle, the fermion superpartner of the gluon predicted by supersymmetry. ... In particle physics, chargino refers to a charged superpartner, i. ... In particle physics, the neutralino is a hypothetical particle and part of the doubling of the menagerie of particles predicted by supersymmetric theories. ... In particle physics, a slepton is a hypothetical bosonic partner of a lepton whose existence is implied by supersymmetry. ...

The MSSM imposes R-parity to explain the stability of the proton. It adds supersymmetry breaking by introducing explicit soft supersymmetry breaking operators into the Lagrangian that is communciated to it by some unknown (and unspecified) dynamics. This means that there are 120 new parameters in the MSSM. Most of these parameters lead to unnacceptable phenomenology such as large flavor changing neutral currents or large electric dipole moments for the neutron and electron. To avoid these problems, the MSSM takes all of the soft susy breaking to be diagonal in flavor space and for all of the new CP violating phases to vanish. R-parity is a concept in particle physics. ... The standard model of particle physics states that protons are stable, i. ... In theoretical physics, soft SUSY breaking is a supersymmetry breaking by the special kind of terms that do not invalidate certain desirable features of supersymmetry, such as the Bose-Fermi cancellation of the ultraviolet divergences contributing to the mass of the Higgs boson. ... In theoretical physics, flavor changing neutral currents (FCNCs) are dangerous fermionic bilinear expressions. ... This article is about the electromagnetic phenomenon. ... CP may stand for: Caminhos de Ferro Portugueses, Portuguese Railways, from 2004 Comboios de Portugal, Portuguese Trains. ...

Theoretical Motivations

There are three prinicple motivations for the MSSM over other theoretical extensions of the Standard Model:

Naturalness
Gauge coupling unification
Dark Matter

These motivations come out without much effort and they are the primary reason why the MSSM is the leading candidate for a new theory to be discovered at collider experiments such as the Tevatron or the LHC. Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... For the pop group, see Les Horribles Cernettes Construction of the CMS detector for LHC at CERN The Large Hadron Collider (short LHC) is a particle accelerator and collider located at CERN. It is currently under construction and scheduled to start operation in 2007. ...

Naturalness

Cancellation of the Higgs boson quadratic mass renormalization between fermionic top quark loop and scalar top squark Feynman diagrams in a supersymmetric extension of the Standard Model

The original motivation for proposing the MSSM was to stabilize the Higgs mass to radiative corrections that are quadratically divergent in the Standard Model (hierarchy problem). In supersymmetric models, scalars are related to fermions and have the same mass. Since fermion masses can not be quadratically divergent, scalar masses inherit the same radiative stability. The Higgs vacuum expectation value is related to the negative scalar mass in the Lagrangian. In order for the radiative corrections to the Higgs mass to not be dramatically larger than the actual value, the the mass of the superpartners of the Standard Model should not be significantly heavier than the Higgs vev -- roughly 100 GeV. This mass scale is being probed currently at the Tevatron and will be more extensively explored at the LHC. Image File history File links Hqmc600. ... Image File history File links Hqmc600. ... The Higgs boson is a hypothetical massive scalar elementary particle predicted to exist by the Standard Model of particle physics. ... In quantum field theory, mass renormalization refers to the quantum corrections to the mass of a particle through its self interactions, or through interactions with other particles. ... Fermions, named after Enrico Fermi, are particles which form totally-antisymmetric composite quantum states. ... The top quark is a third-generation quark with a charge of +(2/3)e. ... In mathematics and physics, a scalar field associates a scalar to every point in space. ... In particle physics, a squark is a hypothetical boson partner of a quark whose existence is implied by supersymmetry. ... In this Feynman diagram, electrons annihilate and become a quark-antiquark pair. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The Standard Model of Fundamental Particles and Interactions The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. ... In theoretical physics, a hierarchy problem is a confusing observation that two fundamental quantities with the same units have vastly different values, and therefore the naïve calculation based on dimensional analysis can lead to incorrect results. ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... For the pop group, see Les Horribles Cernettes Construction of the CMS detector for LHC at CERN The Large Hadron Collider (short LHC) is a particle accelerator and collider located at CERN. It is currently under construction and scheduled to start operation in 2007. ...

Gauge Coupling Unification

If the superpartners of the Standard Model are near the TeV scale, then measured gauge couplings of the three gauge groups unify at High energies. The beta functions for the MSSM gauge couplings are given by A separate article treats the beta-function (written with a hyphen) of physics. ...

Gauge Group	$alpha^{-1}(M_{Z^0})$	$b_0^{MSSM}$
SU(3)	8.5	$- 3$
SU(2)	29.6	$+ 1$
U(1)	59.2	$+6frac{3}{5}$

where $alpha^{-1}_{1}$ is measured in SU(5) normalization -- a factor of $frac{3}{5}$ different than the Standard Model's nomalization and predicted by Georgi-Glashow SU(5) . This article is in need of attention from an expert on the subject. ...

The condition for gauge coupling unification at one loop is whether the following expression is satisfied $frac{alpha^{-1}_3 - alpha^{-1}_2}{alpha^{-1}_2-alpha^{-1}_1} = frac{b_{0,3} - b_{0,2}}{b_{0,2} -b_{0,1}}$ .

Remarkably, this is precisely satisfied to experimental errors. There are two loop corrections and both TeV-scale and GUT-scale threshold corrections that alter this condition on gauge coupling unification, and the results of more extensive calculations revealt that gauge coupling unification occurs to an accuracy of 1%, though this is about 3 standard deviations from the theoretical expectations (discounting threshold effects). In particle physics, the term threshold effect usually refers to small corrections to rough calculations based on the renormalization group that arise from the detailed behavior near the scale where new physics takes place. ...

Dark Matter

If R-parity is preserved, then the lightest superparticle (LSP) of the MSSM is stable and is a weakly interacting massive particle (WIMP) -- i.e. it does not have electromagnetic or strong interactions. This makes the LSP a good dark matter candidate and falls into the category of cold dark matter (CDM) particle. R-parity is a concept in particle physics. ... LSP can mean: Links Socialistisch Partij, the Belgian section of the CWI Language for Specific Purposes, as in LSP dictionary Layered Service Provider Leading Success People Link State Packet Label Switched Path Liskov substitution principle Line Spectrum Pairs(or line spectral pair)- A kind of digital representation of a filter... In English slang, a wimp is a pushover, or a wishy-washy person. ... This refers to the cosmological use of the term. ... Cold dark matter (or CDM) is a refinement of the big bang theory that contains the additional assumption that most of the matter in the Universe consists of material which cannot be observed by its electromagnetic radiation and hence is dark while at the same time the particles making up...

Discovery of the MSSM at Hadron Colliders

The Tevatron and LHC have active experimental programs searching for supersymmetric particles. Since both of these machines are hadron colliders -- proton antiproton for the Tevatron and proton proton for the LHC -- they search best for strongly interacting particles. Therefore most experimental signature involve production of squarks or gluinos. Since the MSSM has R-parity, the lightest supersymmetric particle is stable and after the the squarks and gluinos decay each decay chain will contain one LSP that will leave the detector unseen. This leads to the generic prediction that the MSSM will produce a 'missing energy' signal from these particles leaving the detector. Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... For the pop group, see Les Horribles Cernettes Construction of the CMS detector for LHC at CERN The Large Hadron Collider (short LHC) is a particle accelerator and collider located at CERN. It is currently under construction and scheduled to start operation in 2007. ... In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ... In particle physics, a squark is a hypothetical boson partner of a quark whose existence is implied by supersymmetry. ... A gluino is a subatomic particle, the fermion superpartner of the gluon predicted by supersymmetry. ... R-parity is a concept in particle physics. ...

Neutralinos

There are four Neutralinos who are fermions and are electrically neutral, the lightest of which is typically stable. Because the lightest neutralino is stable, all supersymmetric cascades decays end up decaying into this particle which leaves the detector unseen and its existence can only be inferred by looking for unbalanced momentum in a detector. The heavier neutralinos typically decay through a $Z 0$ to a lighter neutralino or through a $W^pm$ to chargino. In particle physics, the neutralino is a hypothetical particle and part of the doubling of the menagerie of particles predicted by supersymmetric theories. ...

Charginos

There are two Charginos who are fermions and are electrically charged. The heavier chargino can decay either through $Z 0$ to the lighter chargino. Both can decay through a $W^pm$ to neutralino. In particle physics, chargino refers to a charged superpartner, i. ...

Squarks

The squarks are the scalar superpartners of the quarks and there is one version for each Standard Model quark. Due to phenomenological constraints from flavor changing neutral currents, typically the lighter two generations of squarks have to be nearly the same in mass and therefore are not given distinct names. The superpartners of the top and bottom quark can be split from the lighter squarks and are called stops and [sbottom]]s. In particle physics, a squark is a hypothetical boson partner of a quark whose existence is implied by supersymmetry. ... The word stop has several possible meanings in the English language. ...

Squarks can be produced through strong interactions and therefore are easily produced at hadron colliders. They decay to quarks and neutralinos or charginos which further decay. Squarks are typically pair produced and therefore a typical signal is

$tilde{q}tilde{bar{q}} rightarrow q tilde{N}^0_1 bar{q} tilde{N}^0_1 rightarrow$ 2 jets + Missing energy
$tilde{q}tilde{bar{q}} rightarrow q tilde{N}^0_2 bar{q} tilde{N}^0_1 rightarrow q tilde{N}^0_1 ell bar{ell} bar{q} tilde{N}^0_1 rightarrow$ 2 jets + 2 leptons + Missing energy

Gluinos

Gluinos are Majorana fermionic partners of the gluon which means that they are their own antiparticles. They interact strongly and therefore can be produced significantly at the LHC. They can only decay to a quark and a squark and thus a typical gluino signal is In mathematics and physics, in particular in the theory of the orthogonal groups, spinors are certain kinds of mathematical objects (group representations of Spin(N), roughly speaking) similar to vectors, but which change sign under a rotation of radians. ... In particle physics, gluons are vector gauge bosons that mediate strong color charge interactions of quarks in quantum chromodynamics (QCD). ...

$tilde{g}tilde{g}rightarrow (q tilde{bar{q}}) (bar{q} tilde{q}) rightarrow (q bar{q} tilde{N}^0_1) (bar{q} q tilde{N}^0_1) rightarrow$ 4 jets + Missing energy

Because gluinos are Majorana, gluinos can decay to either a quark--anti-squark or an anti-quark--squark with equal probability. Therefore pairs of gluinos can decay to

$tilde{g}tilde{g}rightarrow (bar{q} tilde{q}) (bar{q} tilde{q}) rightarrow (q bar{q} tilde{C}^+_1) (q bar{q} tilde{C}^+_1) rightarrow (q bar{q} W^+) (q bar{q} W^+) rightarrow$ 4 jets+ $ell^+ ell^+$ + Missing energy

This is a distinctive signature because it has same-sign di-leptons and has very little background in the Standard Model.

Sleptons

Sleptons are the scalar partners of the leptons of the Standard Model. They are not strongly interacting and therefore are not produced very often at hadron colliders unless they are very light. They will typically be found in decays of a charginos and neutralinos if they are light enough to be a decay product In physics, a particle is a lepton if it has a spin of 1/2 and does not experience the strong nuclear force. ...

$tilde{C}^+rightarrow tilde{ell}^+ nu$
$tilde{N}^0 rightarrow tilde{ell}^+ ell^-$

MSSM Fields

Fermions have boson superpartners, and bosons have fermion superpartners. Fermions, named after Enrico Fermi, are particles which form totally-antisymmetric composite quantum states. ... Bosons, named after Satyendra Nath Bose, are particles which form totally-symmetric composite quantum states. ...

SM Particle type	Particle	Symbol	Spin	R-Parity	Superpartner	Symbol	Spin	R-parity
Fermions	Quark	$q$	$begin{matrix} frac{1}{2} end{matrix}$	+1	Squark	$tilde{q}$	0	-1
	Lepton	$ell$	$begin{matrix} frac{1}{2} end{matrix}$	+1	Slepton	$tilde{ell}$	0	-1
Bosons	W	$W$	1	+1	Wino	$tilde{W}$	$begin{matrix} frac{1}{2} end{matrix}$	-1
	B	$B$	1	+1	Bino	$tilde{B}$	$begin{matrix} frac{1}{2} end{matrix}$	-1
	Gluon	$g$	1	+1	Gluino	$tilde{g}$	$begin{matrix} frac{1}{2} end{matrix}$	-1
Higgs bosons	Higgs	$h u, h d$	0	+1	Higgsinos	$tilde{h}_u, tilde{h}_d$	$begin{matrix} frac{1}{2} end{matrix}$	-1

MSSM is an N=1 SUSY model in 3+1 Minkowski spacetime with $frac{SU(3)times SU(2) times U(1)}{mathbb{Z}_6}$ . In physics, spin refers to the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is generated by the motion of its center of mass about an external point. ... Quarks are one of the two basic constituents of matter in the Standard Model of particle physics. ... In particle physics, a squark is a hypothetical boson partner of a quark whose existence is implied by supersymmetry. ... In physics, a particle is a lepton if it has a spin of 1/2 and does not experience the strong nuclear force. ... In particle physics, a slepton is a hypothetical bosonic partner of a lepton whose existence is implied by supersymmetry. ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... For other uses of the word Wino, see Wino. ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... In particle physics, a bino is the hypothetical superpartner of the hypercharge gauge boson predicted by supersymmetry. ... In particle physics, gluons are vector gauge bosons that mediate strong color charge interactions of quarks in quantum chromodynamics (QCD). ... A gluino is a subatomic particle, the fermion superpartner of the gluon predicted by supersymmetry. ... The Higgs boson is a hypothetical massive scalar elementary particle predicted to exist by the Standard Model of particle physics. ... In particle physics, a higgsino is the hypothetical superpartner of the Higgs boson, as predicted by supersymmetry. ... In particle physics, supersymmetry is a hypothetical symmetry that relates bosons and fermions. ... In physics and mathematics, Minkowski space (or Minkowski spacetime) is the mathematical setting in which Einsteins theory of special relativity is most conveniently formulated. ...

The fermionic superpartner of a single Higgs boson would lead to a gauge anomaly, therefore a vector-like pair of Higgsinos must be added meaning that there are two scalar Higgs doublets in the MSSM. Not only that, we need at least two Higgs doublets because the couplings have to be holomorphic. In theoretical physics, a gauge anomaly is an example of an anomaly: it is an effect of quantum mechanics - usually a one-loop diagram - that invalidates the gauge symmetry of a quantum field theory i. ...

MSSM Superfields

MSSM contains vector superfields associated with the gauge group. It also contains the following chiral superfields: In theoretical physics, one often analyzes theories with supersymmetry in which vector superfields play an important role. ... In theoretical physics, one often analyzes theories with supersymmetry in which chiral superfields play an important role. ...

field	multiplicity	representation	Z₂-parity
Q	3	$(3,2)_{frac{1}{6}}$	-
U^c	3	$(bar{3},1)_{-frac{2}{3}}$	-
D^c	3	$(bar{3},1)_{frac{1}{3}}$	-
L	3	$(1,2)_{-frac{1}{2}}$	-
E^c	3	$(1,1) 1$	-
H_u	1	$(1,2)_{frac{1}{2}}$	+
H_d	1	$(1,2)_{-frac{1}{2}}$	+

The MSSM Lagrangian

The Lagrangian for the MSSM contains several pieces.

The first is the Kahler potential for the matter and Higgs fields which produces the kinetic terms for the fields.

The second piece is the gauge field superpotential that produces the kinetic terms for the gauge bosons and gauginos.

The next term is the superpotential for the matter and Higgs fields. These produce the Yukawa couplings for the Standard Model fermions and also the mass term for the Higgsinos. After imposing R-parity, the renormalizable, gauge invariant) operators in the superpotential are

$W = μ H u H d + y u H u Q U c + y d H d Q D c + y l H d L E c$ Superpotential is a concept from particle physics supersymmetry. ... In particle physics, a higgsino is the hypothetical superpartner of the Higgs boson, as predicted by supersymmetry. ... R-parity is a concept in particle physics. ... In physics, the adjective renormalizable refers to a theory (usually a quantum field theory) in which all ultraviolet divergences, infinities and other seemingly meaningless results can be cured by the process of renormalization. ... Gauge theories are a class of physical theories based on the idea that symmetry transformations can be performed locally as well as globally. ...

The constant term is unphysical in global supersymmery.

Soft Susy Breaking

The last piece of the MSSM Lagrangian is the soft supersymmetry breaking Lagrangian. The vast majority of the parameters of the MSSM are in the susy breaking Lagrangian. The soft susy breaking are divided into roughly three pieces.

The first are the gaugino masses

$mathcal{L} = m_{frac{1}{2}} tilde{lambda}tilde{lambda} + h.c.$

Where $tilde{lambda}$ are the gauginos and $m_{frac{1}{2}}$ is different for the wino, bino and gluino.

The next are the soft masses for the scalar fields

$mathcal{L} = m_0 phi^dagger phi$

where $φ$ are any of the scalars in the MSSM and $m 0$ are $3times 3$ hermitean matrices for the squarks and sleptons of a given gauge quantum numbers.

Finally there are the $A$ and $B$ terms which are given by

$mathcal{L} = B_{mu} h_u h_d + A h_u q u^c+ A h_d q d^c +A h_d l e^c + h.c.$

where the lowercase field names are the scalars of a given supermultiplet. The $A$ terms are $3times 3$ comples matrices much as the scalar masses are.

The CMSSM

There is a particular ansatz for the soft supersymmetry breaking that is very popular in the literature known as the 'Constrained MSSM' (fomerly called mSugra). In this ansatz, all of the squark and slepton soft masses are assumed to be the same at the GUT scale and to not violate flavor. Similarly all of the A-terms are also taken to be flavor independent and universal at the GUT scale as well. Finally all of the gaugino masses are taken to the same at the GUT scale. With this ansatz, the parameters are RGE evolved to the TeV scale and masses and interactions of the particles are studied. The useful aspect of this parameterization of supersymmetry breaking is that it results in phenomologically acceptable parameters and only has 4 continuous parameters to vary and one sign. The down side is that no known theory of supersymmetry breaking is known to give this exact pattern of supersymmetry breaking.

Electroweak Symmetry Breaking

Electroweak symmetry is broken using the Higgs mechanism where a Higgs doublet acquires a vacuum expectation value (vev). The MSSM contains two Higgs doublet, $h u$ and $h d$ where the subscripts indicate whether the Higgs couples to up-type fermions or down-type fermions (down quarks and charged leptons): In physics, the electroweak theory presents a unified description of two of the four fundamental forces of nature: electromagnetism and the weak nuclear force. ... The Higgs mechanism, originally discovered by the British physicist Peter Higgs (building on a previous suggestion by Philip Anderson in condensed matter physics), is the mechanism that gives masses to all elementary particles in particle physics. ... In quantum field theory the vacuum expectation value (also called condensate) of an operator is its average, expected value in the vacuum. ...

$mathcal{L} = y_u, h_u q u^c + y_d, h_d q d^c+ y_e, h_d l e^c + h.c.$

In order to have all the Standard Model fermions acquire mass, both Higgs doublet much acquire a vev

$langle h_urangle = v_u/sqrt{2} ;; langle h_drangle= v_d/sqrt{2}$

usually these are rewritten in terms of the effective electroweak vev and the ratio of the two vev

$v^2 = v_u^2 + v_d^2$ $tan beta = frac{v_u}{v_d}$ .

The Higgs Mass

The mass of the lightest Higgs boson is set by the Higgs quartic coupling. Quartic couplings are not soft supersymmetry breaking parameters since they lead to a quadratic divergences to the Higgs mass. Furthermore, there are no supersymmetric parameters to make the Higgs mass a free parameter in the MSSM (though not in non-minimal extensions). This means that Higgs mass is a prediction of the MSSM. The Higgs boson was not found at LEP II and the four experiments placed a lower limit on the Higgs mass of 114.4 GeV. This lower limit is significantly above where the MSSM would typically predict it to be, and while it does not rule out the MSSM, the non-discovery of the Higgs makes proponents of the MSSM nervous. If the Higgs is found above 125 GeV (along with the other superparticles) at the LHC, then this will strongly hint at new dynamics beyond the MSSM such as the 'Next to Minimal Supersymmetric Standard Model' (NMSSM). The MSSM Higgs Mass is a prediction of the Minimal Supersymmetric Standard Model. ...

Neutralinos and Charginos

After electroweak symmetry breaking, the Higgsinos, Binos and Winos will mix with each other. The mass eigenstates are called Neutralinos and Charginos depending on whether the particles are electrically neutral or charged. Typically the lightest neutralino is the lightest supersymmetric particle and makes up the dark matter of the universe. In particle physics, a higgsino is the hypothetical superpartner of the Higgs boson, as predicted by supersymmetry. ... In particle physics, a bino is the hypothetical superpartner of the hypercharge gauge boson predicted by supersymmetry. ... The word Wino can refer to: A slang term for someone consuming large amounts of alcohol; see Wino (slang term). ... In particle physics, the neutralino is a hypothetical particle and part of the doubling of the menagerie of particles predicted by supersymmetric theories. ... In particle physics, chargino refers to a charged superpartner, i. ...

Problems with the MSSM

There are several problems with the MSSM -- most of them falling into the understanding the parameters.

The mu Problem
Flavor universality of soft masses and A-terms
Smallness of CP violating phases

More recently physicists have become concerned about the non-discovery of the Higgs boson, or any superpartner at LEP II or the Tevatron. The term Higgs appears in: Higgs boson, theoretical elementary particle Peter Higgs, physicist Higgs Laws of Convergence Simon Higgs, author of the Higgs Laws This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ...

Theories of Supersymmetry Breaking

A large amount of theoretical effort has been spent trying to understand the mechanism for soft supersymmetry breaking that produces the desired properties in the superpartner masses and interactions. The three most extensively studied mechanisms are

Gravity Mediated Supersymmetry Breaking
Gauge Mediated Supersymmetry Breaking (GMSB)
Anomaly Mediated Supersymmetry Breaking (AMSB)

External links

A Supersymmetric Primer by Stephen P. Martin
Particle Data Group review of MSSM and search for MSSM predicted particles

Categories: Supersymmetry | Particle physics

Results from FactBites:

supersymmetry: Definition and Much More from Answers.com (2545 words)
	The first realistic supersymmetric version of the Standard Model was proposed in 1981 by Howard Georgi and Savas Dimopoulos and is called the minimal supersymmetric Standard Model or MSSM for short.
	The standard paradigm for incorporating supersymmetry into a realistic theory is to have the underlying dynamics of the theory be supersymmetric, but the ground state of the theory does not respect the symmetry and supersymmetry is broken spontaneously.
	Supersymmetric quantum mechanics often comes up when studying the dynamics of supersymmetric solitons and due to the simplified nature of having fields only functions of time (rather than space-time), a great deal of progress has been made in this subject and is now studied in its own right.

mssm (945 words)
	In the supersymmetric extension, the fact that these couplings are determined in terms of known gauge couplings leads to an important prediction for the Z mass when studying the electroweak symmetry breaking pattern.
	This was explored in the first realizations of the supersymmetric extensions of the standard model, but subsequently was neglected in favor of the supergravity messenger.
	In this scheme the lightest supersymmetric particle is the gravitino.

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