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| SUSY | |
|---|---|
| Name | SUSY |
| Field | Theoretical physics |
| Notable people | Julius Wess, Bruno Zumino, Pierre Fayet, Howard Georgi |
| First proposed | 1970s |
SUSY
SUSY is a proposed symmetry in high-energy physics postulating a correspondence between bosonic and fermionic degrees of freedom. It was developed in the early 1970s in the context of quantum field theory and has driven research programs at institutions such as CERN, SLAC National Accelerator Laboratory, Fermilab, and universities including Harvard University and Princeton University. The framework influenced developments in string theory pursued at places like Institute for Advanced Study and Perimeter Institute for Theoretical Physics, and motivated experimental programs at facilities including the Large Hadron Collider and the Tevatron.
SUSY extends the Poincaré symmetry used in Special Relativity and Quantum Field Theory by introducing generators that transform fermions into bosons and vice versa; foundational contributors include Julius Wess, Bruno Zumino, Pierre Fayet, and Howard Georgi. The hypothesis offers solutions to problems encountered in the Standard Model such as the hierarchy problem encountered by the Higgs boson and radiative corrections studied in the context of Gerard 't Hooft's naturalness criteria. SUSY appears naturally in constructions of Superstring theory and in attempts to unify interactions pursued in Grand Unified Theory programs associated with groups like SU(5) and SO(10). Experimental null results have redirected focus toward models with broken or hidden realizations studied by researchers at KEK and in collaborations such as ATLAS and CMS.
The basic theoretical framework introduces supercharges that extend space-time symmetries and produce multiplets pairing particles of differing spin; early formal development was influenced by work at CERN Theory Division and by lectures at Les Houches Summer School. Supersymmetric Lagrangians respect graded Lie algebras and are built from chiral and vector multiplets, employing mechanisms analogous to those developed by Richard Feynman in perturbation theory and by Ken Wilson in renormalization group analysis. Supersymmetry breaking mechanisms—such as gravity-mediated scenarios explored with inputs from Supergravity research and gauge-mediated schemes discussed at conferences in Munich—introduce soft terms that preserve renormalizability while lifting mass degeneracies; sources of breaking are often modeled after ideas from Edward Witten and Savas Dimopoulos. Theoretical consistency conditions link SUSY to anomaly cancellation calculations pioneered in studies by Michael Green and John Schwarz.
A wide taxonomy exists: minimal realizations like the Minimal Supersymmetric Standard Model (MSSM) contrast with extensions such as the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and models with Dirac gauginos inspired by work at Tokyo University and MIT. High-scale frameworks include gravity-mediated, gauge-mediated, and anomaly-mediated SUSY breaking scenarios, each associated historically with research groups at Stanford University, Caltech, and Rutgers University. Alternative constructions include split supersymmetry motivated by landscape arguments from Stanford Institute for Theoretical Physics research, low-scale realizations considered by groups at Imperial College London, and models embedded in E8×E8 heterotic string theory studied by teams at Uppsala University and Oxford University.
Phenomenological predictions involve superpartners such as sleptons, squarks, neutralinos, charginos, and gluinos, which have been targets for searches at Large Hadron Collider experiments ATLAS and CMS as well as at LEP and Tevatron experiments. Signatures include missing transverse energy used in analyses inspired by techniques from CDF and DØ, cascade decays resembling event topologies discussed at Moriond Conferences, and long-lived particles investigated in studies at LHCb and Belle II. Collider phenomenology interfaces with flavor physics constraints coming from experiments such as BaBar and Belle, and with precision electroweak measurements performed at LEP and in analyses by Particle Data Group.
Extensive direct searches for superpartners have set limits on masses and cross sections through analyses published by collaborations including ATLAS, CMS, CDF, and DØ. Indirect constraints arise from precision observables measured at Z boson and W boson facilities, from rare decay results from LHCb and NA62, and from electric dipole moment bounds measured in laboratories at Los Alamos National Laboratory and Brookhaven National Laboratory. Null results at the Large Hadron Collider and reinterpreted limits from Tevatron data have pushed favored parameter regions to higher masses or to compressed spectra studied at workshops at Les Houches.
Supersymmetric extensions often provide dark matter candidates such as the lightest neutralino, gravitino, or axino; these scenarios intersect with cosmological probes including observations by Planck (spacecraft), WMAP, and large-scale surveys like Sloan Digital Sky Survey. Thermal freeze-out calculations for weakly interacting massive particles draw on techniques used in early universe studies by researchers at Princeton University and University of Chicago, while nonthermal production mechanisms have been explored in contexts connected to Inflation (cosmology) models developed by Alan Guth and Andrei Linde. Constraints from indirect detection experiments like Fermi Gamma-ray Space Telescope and direct detection efforts at XENON and LUX-ZEPLIN inform viable parameter space.
The mathematical formalism employs graded algebras, superfields, and superspace coordinates; foundational mathematics draws on work by Elie Cartan in spinor theory and later formalizations by researchers at Princeton University and Cambridge University. Superspace techniques using Grassmann variables were formalized in lectures and papers from Les Houches and integrated into algebraic geometry approaches applied in Superstring theory and M-theory investigations at Caltech and Rutgers University. Cohomological methods and index theorems used in anomaly studies connect to mathematical results by Atiyah–Singer and to geometric model building pursued at Institute for Advanced Study.