2020/03/31 by Vedran Brdar, M. Lindner, Manfred Lindner +2
Mathematics · Physics and Astronomy · #Dark Matter and Cosmic Phenomena #Geometry #Lepton #Mathematics #Neutrino #Neutrino Physics Research #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Scalar (mathematics) #astro-ph.CO #hep-ph
paper · pdf · doi:10.1103/physrevd.101.115001
published as Phys. Rev. D 101, 115001 (2020) · 17 pages, 7 figures, calculations related to IR divergence added, PRD published version
openalex created_date 2020/03/23 · arxiv created 2020/05/14 · openalex publication_date 2020/06/01 · arxiv updated 2020/06/03 · openalex updated_date 2026/08/05
Given the elusive nature of neutrinos, their self-interactio is particularly difficult to probe. Nevertheless, upper limits on the strength of such an interaction can be set by using data from terrestrial experiments. In this work, we focus on additional contributions to the invisible decay width of Z boson as well as the leptonic \ensuremathτ decay width in the presence of a neutrino coupling to a relatively light scalar. For invisible Z decays, we derive a complete set of constraints by considering both three-body bremsstrahlung as well as the loop correction to two-body decays. While the latter is usually regarded to give rather weak limits, we find that through the interference with the Standard Model diagram it actually yields a competitive constraint. As far as leptonic decays of \ensuremathτ are concerned, we derive a limit on neutrino self-interactions that is valid across the whole mass range of a light scalar mediator. Our bounds on the neutrino self-interaction are leading for m_\ensuremathφ\ensuremath\gtrsim300 MeV and interactions that prefer \ensuremathν_\ensuremathτ. Bounds on such \ensuremathν-philic scalars are particularly relevant in light of the recently proposed alleviation of the Hubble tension in the presence of such couplings.