Cline, J. M., & Vincent, A. C. (2013). Cosmological origin of anomalous radio background. J. Cosmol. Astropart. Phys., 02(2), 011–23pp.
Abstract: The ARCADE 2 collaboration has reported a significant excess in the isotropic radio background, whose homogeneity cannot be reconciled with clustered sources. This suggests a cosmological origin prior to structure formation. We investigate several potential mechanisms and show that injection of relativistic electrons through late decays of a metastable particle can give rise to the observed excess radio spectrum through synchrotron emission. However, constraints from the cosmic microwave background (CMB) anisotropy, on injection of charged particles and on the primordial magnetic field, present a challenge. The simplest scenario is with a greater than or similar to 9 GeV particle decaying into e(+)e(-) at a redshift of z similar to 5, in a magnetic field of similar to 5 μG, which exceeds the CMB B-field constraints, unless the field was generated after decoupling. Decays into exotic millicharged particles can alleviate this tension, if they emit synchroton radiation in conjunction with a sufficiently large background magnetic field of a dark U(1)' gauge field.
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Alonso-Alvarez, G., Cline, J. M., Laurent, B., & Rahaman, U. (2025). Dark photon distortions of NOνA and T2K neutrino oscillations. Eur. Phys. J. C, 85(6), 635–8pp.
Abstract: Dark photons coupling to L-mu-L-tau lepton number difference are a highly studied light dark matter candidate, with potential to be discovered through their impact on terrestrial neutrino oscillation experiments. We re-examine this in the light of claimed tensions between the NO nu A and T2K long baseline experiments, also taking into account data from the MINOS experiment. We obtain leading limits on the L-mu-L-tau gauge coupling g ' versus dark photon mass m(A '), improving upon previous bounds by up to a factor of five. We find no statistically significant alleviation of the tension from inclusion of the new physics effect.
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