MSSM Fields
Fermions have bosonic superpartners (called sfermions), and bosons have fermionic superpartners (called bosinos). For most of the Standard Model particles, doubling is very straightforward. However, for the Higgs boson, it is more complicated.
A single Higgsino (the fermionic superpartner of the Higgs boson) would lead to a gauge anomaly and would cause the theory to be inconsistent. However if two Higgsinos are added, there is no gauge anomaly. The simplest theory is one with two Higgsinos and therefore two scalar Higgs doublets. Another reason for having two scalar Higgs doublets rather than one is in order to have Yukawa couplings between the Higgs and both down-type quarks and up-type quarks; these are the terms responsible for the quarks' masses. In the Standard Model the down-type quarks couple to the Higgs field (which has Y=-1/2) and the up-type quarks to its complex conjugate (which has Y=+1/2). However in a supersymmetric theory this is not allowed, so two types of Higgs fields are needed.
| SM Particle type | Particle | Symbol | Spin | R-Parity | Superpartner | Symbol | Spin | R-parity |
|---|---|---|---|---|---|---|---|---|
| Fermions | Quark | +1 | Squark | 0 | -1 | |||
| Lepton | +1 | Slepton | 0 | -1 | ||||
| Bosons | W | 1 | +1 | Wino | -1 | |||
| B | 1 | +1 | Bino | -1 | ||||
| Gluon | 1 | +1 | Gluino | -1 | ||||
| Higgs bosons | Higgs | 0 | +1 | Higgsinos | -1 |
Read more about this topic: Minimal Supersymmetric Standard Model
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