Measurement of Boson Self Couplings at LEP and Search for Anomalies

Abstract

With center of mass energies up to 209 GeV of LEP II, massive W and Z bosons can be produced in pairs and jointly with photons. This allows to study boson-boson couplings. Since the W and Z bosons are unstable and decay into fermions, two- and four-fermion final states, accompanied possibly by photons, play an important role for these measurements. The couplings of the W to other bosons have been measured to be g1Z = 0.990+0.023-0.024, kappa_gamma = 0.896+0.058-0.056, and lambda_gamma = -0.023 +0.025 -0.023. They are in agreement with the Standard Model expectation of g1Z = 1, kappa_gamma = 1, and lambda_gamma = 0. No sign for couplings of three neutral bosons, parametrized by the couplings f_i^V and h_i^V, and for anomalous couplings of four gauge bosons, parametrized by a_0, a_n and a_c has been found.Comment: LaTex, 6 pages, 9 figures, to appear in the proceedings of the Conference: XXXVII Rencontres de Moriond: Electroweak Interactions and Unified Theories. Systematics added, more recent values for the neutral triple gauge boson couplings, sign swap correction for quartic boson couplings, new limits for quartic couplings from the Z gamma gamma final state, reference adde