Four-fermion production and limits on anomalous couplings at LEP-2

TL;DR

This paper reviews LEP-2 measurements of four-fermion processes, testing the Standard Model and setting limits on anomalous gauge couplings, with implications for new physics searches and background estimation.

Contribution

It provides a comprehensive combination and analysis of LEP-2 four-fermion data, including precision measurements of gauge couplings and constraints on anomalous interactions.

Findings

Standard Model predictions are confirmed within current experimental accuracy.

Charged triple gauge boson self-couplings measured with a few percent precision.

Limits on anomalous gauge couplings are established, constraining new physics models.

Abstract

Electroweak processes with four fermions in the final state were measured extensively at LEP-2 in e+e- collisions with centre-of-mass energies up to 209 GeV. By combining the results obtained by Aleph, Delphi, L3 and Opal, the predictions from the Standard Model were probed at the level of their present accuracy. An important outcome was the possibility to measure the predicted charged triple gauge boson self-couplings with a precision of a few percent. Moreover studies of four-fermion processes allowed new physics to be searched for by looking for anomalous gauge boson self-couplings. The measurements reported are also relevant to direct searches for new particles at LEP, as four-fermion processes contribute an important background in several cases. The latest results from the LEP experiments - some of which are now available in finalized form - and their combination are reviewed and discussed.