2022 Impact factor 4.4
Particles and Fields
Eur. Phys. J. C 13, 553-572
DOI 10.1007/s100520000315

Tests of the standard model and constraints on new physics from measurements of fermion-pair production at 189GeV at LEP

The OPAL Collaboration

G.Abbiendi 2 - et al.

2Dipartimento di Fisica dell' Università di Bologna and INFN, I-40126 Bologna, Italy

Received: 9 July 1999 / Published online: 17 February 2000 - © Springer-Verlag 2000

Cross-sections and angular distributions for hadronic and lepton pair final states in e+e- collisions at a centre-of-mass energy near 189GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. The results are used to measure the energy dependence of the electromagnetic coupling constant $\alpha_{\mathrm{em}}$, and to place limits on new physics as described by four-fermion contact interactions or by the exchange of a new heavy particle such as a sneutrino in supersymmetric theories with R-parity violation. A search for the indirect effects of the gravitational interaction in extra dimensions on the $\mu^+\mu^-$ and $\tau^+\tau^-$ final states is also presented.

Copyright Società Italiana di Fisica, Springer-Verlag 2000