Department of
Physics and Astronomy

 

Precision Electroweak Tests

The standard model is a mathematically consistent renormalizable field theory which predicts or is consistent with all known aspects of the elementary particles and their interactions over an enormous range of probes and scales. In particular, it is now clear that, with the possible exception of the Higgs sector, the standard electroweak model is the correct theory of nature to an excellent approximation down to a distance scale of cm. Precision neutral current, charged current, and Z and W pole experiments have established or supported the framework of renormalizable field theory and of gauge theories; have established the gauge group; have confirmed the fermion representations; have successfully confirmed the predictions for the existence, masses, and properties of the electroweak gauge bosons; have confirmed or led to successful predictions for higher order effects such as the running of the electromagnetic fine structure constant, the top quark mass, and the strong coupling constant; have searched for and excluded large regions of parameter space associated with alternative symmetry breaking mechanisms and other possible new physics beyond the standard model; and have shown that the strong and electroweak coupling constants are consistent with supersymmetric grand unification.

Scientists at the University of Pennsylvania have long been involved with many aspects of this program. Experiments include neutrino scattering experiments at Fermilab and Brookhaven and the direct discovery of the top quark at Fermilab. Theoretical and phenomenological efforts include a long-term ongoing project to systematically collect all precision data and apply the best possible theoretical analysis for testing the standard model, determining its parameters, and searching for new physics.


Paul Langacker (pgl@langacker.hep.upenn.edu)