selectrons

Selectrons are the scalar superpartners of the electron in supersymmetric theories, such as the Minimal Supersymmetric Standard Model (MSSM). Each chiral state of the electron has a scalar partner: a left-handed selectron ẽL and a right-handed selectron ẽR. These gauge eigenstates can mix through electroweak symmetry breaking and Yukawa couplings, yielding two mass eigenstates typically denoted ẽ1 and ẽ2, ordered by increasing mass. In many models the lighter state is dominantly ẽR.

Selectrons carry electric charge and spin zero, and they interact with photons and Z bosons, as well as with neutralinos and charginos, through supersymmetric couplings. They can be produced in pairs in high-energy collisions via Drell-Yan processes mediated by a virtual photon or Z, and, in e+e− colliders, by t-channel neutralino exchange in addition to s-channel gauge bosons. They predominantly decay to an electron and a neutralino (the lightest neutralino χ̃^0_1 if R-parity is conserved), ẽ → e χ̃^0_1, while ẽL can also decay to a neutrino and a chargino χ̃^− when kinematically allowed.

Experiments have not observed selectrons. Searches at LEP, the Tevatron, and the LHC have set lower bounds on their masses that depend on the rest of the SUSY spectrum, particularly the neutralino mass and the mass splitting with the selectron. In typical MSSM scenarios with a stable lightest neutralino, the lower bounds lie in the several hundred GeV range, with exact values varying by model assumptions. Current results are most robust for simple, well-separated spectra but can be weakened for compressed spectra.

Selectrons are a central feature of supersymmetric phenomenology and serve as a test bed for the mechanism of SUSY breaking and dark matter candidates, since their decays are tied to the neutralino sector and R-parity conservation.