Supersymmetry (SUSY) is a theoretical framework in particle physics that proposes a symmetry between fermions and bosons—the two fundamental classes of particles. According to SUSY, every known particle has a corresponding superpartner whose spin differs by half a unit.
- Fermions (such as electrons and quarks), which have half-integer spins, would have bosonic superpartners (like selectrons and squarks) with integer spins.
- Bosons (like photons and gluons), which have integer spins, would have fermionic superpartners (like photinos and gluinos) with half-integer spins.
Key motivations for SUSY include:
- Unification of forces: SUSY helps the running coupling constants of the strong, weak, and electromagnetic forces to converge more precisely at high energies, supporting Grand Unification Theories (GUTs).
- Solution to the hierarchy problem: SUSY stabilizes the mass of the Higgs boson by canceling out large quantum corrections.
- Dark matter candidate: SUSY predicts a stable, neutral, weakly interacting particle—often the lightest supersymmetric particle (LSP)—which could account for dark matter.
Despite its theoretical appeal, no superpartners have been observed so far in experiments like those at the Large Hadron Collider (LHC), leading to increasingly strict limits on their possible masses.
Still, SUSY remains a powerful idea in theoretical physics, offering a deeper structure to the Standard Model and guiding the search for new physics beyond current experimental reach.