Minimal Supersymmetric Standard Model

The Minimal Supersymmetric Standard Model (MSSM) extends the Standard Model by pairing known particles with superpartners and adding two Higgs doublets. It is the simplest supersymmetric model with the Standard Model’s gauge group and matter content.

Supersymmetry: A symmetry relating bosons and fermions, whose transformations connect particles with different spin. The MSSM applies this symmetry to the Standard Model’s particles.
MSSM superpotential: The holomorphic function of chiral superfields encoding supersymmetric interactions and mass terms in the MSSM. Its Yukawa and Higgs terms specify the model’s supersymmetric interactions.
Next-to-Minimal Supersymmetric Standard Model: A supersymmetric extension of the Standard Model that adds a gauge-singlet chiral superfield to the MSSM. Its singlet can alter the Higgs sector and address limitations of the MSSM.
Large Hadron Collider: A particle accelerator at CERN that collides protons at the highest energies reached in laboratory experiments. Its searches have placed strong limits on many colored MSSM superpartners.
Electroweak hierarchy problem: The puzzle of why the electroweak scale is far smaller than higher fundamental scales despite quantum corrections. The MSSM was designed to stabilize the Higgs scale through superpartner contributions.
Standard Model: The quantum field theory describing known elementary particles and their electromagnetic, weak, and strong interactions. The MSSM retains its gauge interactions and known matter fields.
Electroweak symmetry breaking: The process by which the electroweak vacuum selects a direction, leaving electromagnetism unbroken and giving particles mass. MSSM Higgs potential parameters must produce the observed electroweak vacuum.
Split supersymmetry: A framework in which scalar superpartners are very heavy while fermionic superpartners remain comparatively light. It relaxes the MSSM expectation of a broadly accessible superpartner spectrum.
Dark matter: Matter inferred from gravitational effects that does not emit or absorb detectable electromagnetic radiation. A stable lightest neutralino can provide a particle candidate for the cosmic dark matter.
Supersymmetry breaking: The mechanism by which supersymmetry, if realized in nature, fails to appear in observed particle masses. Its unknown origin leaves MSSM soft parameters largely unconstrained.

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