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| stau (supersymmetric) | |
|---|---|
| Name | Stau |
| Other names | supersymmetric tau slepton |
| Composition | scalar superpartner of the Tau lepton |
| Generation | third |
| Charge | −1 e |
| Mass | model-dependent |
| Interactions | electromagnetic interaction, weak interaction, Yukawa interaction |
stau (supersymmetric)
The stau is the scalar superpartner of the Tau lepton predicted in supersymmetry extensions of the Standard Model. It appears in theoretical frameworks such as the Minimal Supersymmetric Standard Model and plays a central role in collider phenomenology, dark matter coannihilation scenarios, and searches reported by collaborations such as ATLAS and CMS. Experimental efforts at facilities like the Large Hadron Collider and proposed machines like the International Linear Collider aim to constrain stau properties across multiple mass ranges.
In supersymmetric frameworks motivated by Grand Unified Theory proposals and solutions to the hierarchy problem, scalar partners of fermions—sleptons including the stau—arise naturally. The stau participates in interactions governed by gauge groups of SU(3), SU(2), and U(1), with phenomenology sensitive to soft-breaking parameters introduced in constructions by authors connected to Gravity-mediated supersymmetry breaking, Gauge-mediated supersymmetry breaking, and Anomaly-mediated supersymmetry breaking. Accelerator searches by teams from CERN, Fermilab, and DESY have framed experimental strategies for long-lived and prompt stau signatures.
The stau field emerges when implementing N=1 supersymmetry and constructing supermultiplets that pair the Tau lepton with complex scalar components. In the Minimal Supersymmetric Standard Model the interaction terms reflect Yukawa coupling strengths tied to third-generation parameters first discussed in works associated with Georgi–Glashow style unification and explored by research groups at institutions like MIT, Caltech, and Stanford University. Renormalization group evolution from high-scale frameworks such as SO(10) or SU(5) unification affects stau soft masses, mixing angles, and thresholds first computed in collaborations involving CERN theory and university groups including Harvard University and Princeton University.
Stau mass eigenstates result from mixing between left- and right-handed scalar partners; the matrix entries depend on parameters such as the tau Yukawa, trilinear soft term A_tau, and the higgsino mass parameter μ, topics analyzed by theorists at Yale University and Columbia University. The lighter eigenstate may be the lightest charged slepton, with decays into neutralinos or gravitinos depending on contexts developed in studies affiliated with SLAC National Accelerator Laboratory and Imperial College London. Typical decay channels include two-body modes to a neutralino plus a tau (signature analyses used by ATLAS and CMS) and, in gauge-mediated scenarios championed by groups at CERN and KEK, decays to a gravitino plus tau producing displaced vertices studied by the LHCb collaboration. Branching ratios are computed in tools maintained by collaborations at Fermilab and university groups tied to MadGraph and PYTHIA development.
Production mechanisms include Drell–Yan pair production, cascade decays from heavier gluinos or squarks as modeled by teams at Brookhaven National Laboratory and University of Cambridge, and direct production in e+e− collisions proposed for the International Linear Collider. Detection strategies emphasize tau-identification techniques developed at ATLAS and CMS, time-of-flight and ionization measurements exploited in heavy stable charged particle searches led by CERN experiments, and displaced vertex reconstruction methods implemented in LHCb. Simulation frameworks such as Geant4 and analysis software from collaborations at Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory are central to sensitivity estimates.
A long-lived stau affects primordial nucleosynthesis calculations originally refined by researchers at Princeton University and University of Chicago and can catalyze bound-state effects altering light-element abundances discussed in studies tied to Perimeter Institute and Kavli Institute groups. In dark matter coannihilation scenarios explored by theorists at CERN and University of California, Berkeley, stau–neutralino mass splittings determine relic density computations used in global fits from collaborations at SLAC and DESY. Astrophysical constraints may also derive from searches for anomalous heavy isotopes in experiments conducted at institutions like Lawrence Livermore National Laboratory and Brookhaven National Laboratory.
Collider limits on stau masses and lifetimes are published by ATLAS, CMS, and earlier by LEP experiments at CERN; bounds depend on assumptions about the lightest supersymmetric particle and were informed by analyses from groups at Fermilab and university consortia. Long-lived charged-stable stau searches provide complementary constraints from heavy charged particle analyses undertaken by teams at CERN and SLAC, while dedicated e+e− constraints derive from work at LEP involving collaborations such as ALEPH and OPAL. Global fits combining collider data and cosmological observations have been performed by collaborations including GAMBIT and research groups at Imperial College London.
Model variations include scenarios where the stau is the next-to-lightest supersymmetric particle in Gravity-mediated supersymmetry breaking frameworks studied at Cambridge University and where gauge mediation yields prompt or displaced decays as developed by groups at KEK and CERN. Compressed spectra motivated by Naturalness arguments and scans run by teams at University of Oxford and ETH Zurich change experimental signatures, while extensions such as R-parity violation and hidden-sector portals explored at Institute for Advanced Study introduce alternate decay chains and search strategies pursued by ATLAS and CMS analysis groups.
Category:Supersymmetric particles