Slepton

A slepton is the scalar superpartner of a lepton in supersymmetric theories. In the minimal supersymmetric Standard Model (MSSM) there are three charged sleptons corresponding to the electron, muon, and tau, known as the selectron, smuon, and stau. Each charged slepton flavor has left- and right-handed states, and the physical mass eigenstates result from mixing. The superpartners of neutrinos are the sneutrinos, which are electrically neutral; in the MSSM they are typically the partners of the left-handed lepton doublets.

Sleptons are spin-0 particles and carry the same lepton flavor quantum numbers as their Standard Model partners. Their masses arise from supersymmetry-breaking terms and D-term contributions, with possible mixing between left- and right-handed states. Mixing is most significant for the staus because of the relatively large tau Yukawa coupling. Sneutrino masses mainly reflect the soft terms associated with the lepton doublets and are usually close to other sleptons of the same generation.

In collider experiments, sleptons are produced primarily in pairs through electroweak interactions. In R-parity conserving models, the lightest neutralino is often the lightest supersymmetric particle, so sleptons typically decay to a lepton and a neutralino, producing events with leptons and missing energy. Sneutrinos can decay to a lepton and a chargino or to a neutralino and a neutrino, depending on the mass spectrum.

No experimental evidence for sleptons has been observed to date. LEP and LHC searches have set lower bounds on slepton masses, typically in the hundreds of GeV range for certain spectra and decay channels. Sleptons feature in phenomenology related to the muon anomalous magnetic moment, lepton flavor violation in the presence of flavor mixing, and possible dark matter scenarios involving a neutralino LSP.