Abstract
The gauged $U(1{)}_{{L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}}$ extension of the Standard Model is a very simple framework that can alleviate the tension in muon anomalous magnetic dipole moment, reinforced by the recent Fermilab measurement. We explore experimental probes of the $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ target with a general treatment of kinetic mixing between the ${Z}^{\ensuremath{'}}$ gauge boson and the photon. The physical value of the kinetic mixing depends on a free parameter of the model and energy scale of a process. We find neutrino constraints on the $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ target including Borexino, coherent elastic neutrino-nucleus scattering, and white dwarfs are sensitive to this freedom and can be lifted if the kinetic mixing lies in proximity of zero at low momentum transfer. As a further step, we explore ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$ charged dark matter with a thermal origin and show that the same scenario of kinetic mixing can relax existing direct detection constraints and predict novel recoil energy dependence in the upcoming searches. Future joint effort of neutrino and dark matter experiments and precision spectral measurement will be the key to test such a theory.
Highlights
The quest for physics beyond the Standard Model (SM) is the central focus of particle physics nowadays
We explore neutrino and dark matter (DM) phenomenology in the gauged Uð1ÞLμ−Lτ model that addresses the ðg − 2Þμ tension
A number of experimental probes are controlled by the kinetic mixing between the new gauge boson Z0 and the photon, which depends on the bare kinetic mixing ε0 as a free parameter
Summary
The quest for physics beyond the Standard Model (SM) is the central focus of particle physics nowadays. The constraint on the ðg − 2Þμ target obtained from solar neutrino measurements at the Borexino experiment can be lifted if the kinetic mixing function is suppressed at low momentum transfer (well below the muon mass). We show that a new viable window of DM mass above GeV scale can be opened if the kinetic mixing is suppressed at low momentum transfer, coinciding with the scenario where neutrino constraints are weakened. II we present the gauged Uð1ÞLμ−Lτ model and derive the momentum dependence of a general kinetic mixing It sets the stage for phenomenological discussions of experimental probes using neutrinos and DM in Secs. The other constraints, such as that from the Borexino experiment, are not displayed here because of additional model dependence, as will be clarified below. The viable mass window (5 MeV ≲ mZ0 ≲ 200 MeV) for the ðg − 2Þμ explanation serves as a motivated target for many future experiments [27,28,29,30,31]
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