Constraints on four-Fermi contact interactions from low-energy electroweak experiments

摘要

We investigate the constraints on four-Fermi contact interactions from low-energy lepton-quark and lepton-lepton scattering experiments - polarization asymmetries in electron (muon)-nucleon scattering experiments, cesium and thallium atom parity violation measurements, neutrino-nuclei and neutrino-electron scattering experiments. These constraints are then combined by assuming the lepton and quark universalities and SU(2)_L * U(1)_Y gauge invariance of the contact interaction, which leave independent six lepton-quark and three pure-leptonic interactions. Impacts of these constraints on models with an additional Z-boson are briefly discussed. We also present updates of the low-energy constraints on the S and T parameters.