sleptons

Sleptons are hypothetical scalar particles that are the supersymmetric partners of leptons in supersymmetric extensions of the Standard Model, such as the Minimal Supersymmetric Standard Model (MSSM). Each lepton has a corresponding slepton: charged sleptons for the electron, muon, and tau, and sneutrinos for the neutrino partners. In the MSSM, charged sleptons come in left-handed and right-handed varieties, denoted as \tilde{l}_L and \tilde{l}_R, which can mix to form mass eigenstates, with the tau sector typically showing the strongest mixing due to its larger Yukawa coupling.

Properties and interactions: Sleptons are spin-0 particles. They carry the same electric charge and lepton number as their SM counterparts and interact via electroweak gauge forces and couplings to Higgsinos and gauginos. They do not participate in strong interactions. Their masses arise from soft supersymmetry-breaking terms and electroweak symmetry breaking, and sneutrinos are the scalar partners of neutrinos.

Spectrum: For each lepton generation there are two charged sleptons and one sneutrino. The charged sleptons mix to produce two mass eigenstates, typically labeled \tilde{l}_1 and \tilde{l}_2, with \tilde{l}_1 often being the lighter. The sneutrinos’ masses are determined by the corresponding soft terms and electroweak effects.

Production and decays: In collider experiments, sleptons can be produced in pairs through electroweak processes. They commonly decay into a lepton and a neutralino or chargino, e.g., \tilde{l} -> l \tilde{χ}^0 or l ν \tilde{χ}^±, resulting in final states with leptons and missing energy if the lightest neutralino is the lightest supersymmetric particle (LSP) and stable.

Experimental status: No confirmed slepton discovery has been made. Searches at LEP, the Tevatron, and the LHC have set lower mass limits that depend on model parameters, typically constraining selectrons and smuons above several hundred GeV in many scenarios, with weaker limits for staus.

See also: supersymmetry, MSSM, neutralino, stau, sneutrino.