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SLC/LEP CONSTRAINTS ON UNIFIED MODELS

Apostolos Pilaftsis
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Abstract

We examine the potential of constraining possible nondecoupling effects of heavy neutrinos and Higgs bosons at LEP and SLC that may show up in the nonoblique part of the $Zl_il_j$ couplings. We analyze this type of new-physics interactions within the context of low-energy scenarios motivated by unified theories, such as the Standard Model (SM) with neutral isosinglets, the left-right symmetric model, and the minimal supersymmetric SM. Our analysis comprises a complete set of physical quantities based on the nonobservation of flavour-violating $Z$-boson decays, lepton universality in the decays $Z\to l\bar{l}$, and universality of lepton asymmetries at the $Z$ peak. It is found that these quantities form a set of complementary observables and may hence constrain the parameter space of the theories. Non-SM contributions of new-physics interactions to $R_b=Γ(Z\to b\bar{b})/Γ(Z\to \mbox{hadrons})$ are briefly discussed within these models.

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Apostolos Pilaftsis. 1995-03-06. SLC/LEP CONSTRAINTS ON UNIFIED MODELS. https://arxiv.org/abs/hep-ph/9503242

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