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CONSTRAINTS FROM LEPTON UNIVERSALITY AT THE Z PEAK ON UNIFIED THEORIES

J. Bernabe'u·A. Pilaftsis
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Abstract

We suggest the use of a universality-breaking observable based on lepton asymmetries as derived from the left-right asymmetry and the $τ$ polarization at the $Z$ peak, which can efficiently constrain the parameter space of unified theories. The new observable is complementary to the leptonic partial width differences and it depends critically on the chirality of a possible non-universal $Z$-boson coupling to like-flavour leptons. The LEP/SLC potential of probing universality violation is discussed in representative low-energy extensions of the Standard Model (SM) that could be derived by supersymmetric grand unified theories, such as the SM with left-handed and/or right-handed neutral isosinglets, the left-right symmetric model, and the minimal supersymmetric SM.

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J. Bernabe'u, A. Pilaftsis. 1995-02-14. CONSTRAINTS FROM LEPTON UNIVERSALITY AT THE Z PEAK ON UNIFIED THEORIES. https://doi.org/10.1016/0370-2693(95)00320-k

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