Cosmology with a very light L μ - L τ gauge boson
In this paper, we explore in detail the cosmological implications of an abelian Lμ ― Lτ gauge extension of the Standard Model featuring a light and weakly coupled Z¹. Such a scenario is motivated by the longstanding ~4σ discrepancy between the measured and predicted values of the muon's anomalo...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universidad Autónoma de Madrid |
| Repositorio: | Biblos-e Archivo. Repositorio Institucional de la UAM |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.uam.es:10486/714249 |
| Acceso en línea: | http://hdl.handle.net/10486/714249 https://dx.doi.org/10.1007/JHEP03(2019)071 |
| Access Level: | acceso abierto |
| Palabra clave: | Cosmology of theories beyond the SM beyond standard model neutrino physics Física |
| Sumario: | In this paper, we explore in detail the cosmological implications of an abelian Lμ ― Lτ gauge extension of the Standard Model featuring a light and weakly coupled Z¹. Such a scenario is motivated by the longstanding ~4σ discrepancy between the measured and predicted values of the muon's anomalous magnetic moment, (g ― 2)μ, as well as the tension between late and early time determinations of the Hubble constant. If sufficiently light, the Z¹ population will decay to neutrinos, increasing the overall energy density of radiation and altering the expansion history of the early universe. We identify two distinct regions of parameter space in this model in which the Hubble tension can be signi cantly relaxed. The rst of these is the previously identi ed region in which a ~10 ― 20MeV Z¹ reaches equilibrium in the early universe and then decays, heating the neutrino population and delaying the process of neutrino decoupling. For a coupling of gμ― τ ≃(3 ― 8) 10⁻⁴ , such a particle can also explain the observed (g ― 2) anomaly. In the second region, the Z¹ is very light (mz₁ ~ 1 eV to MeV) and very weakly coupled (gμ― τ ~ 10⁻¹³ to 10⁻⁹) |
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