Comment: 41 pages, 6 figures, 13 tables, discussions and references added, published in PRD

Comment: 25 pages, 10 figures

Heavy nearly-sterile neutrinos are a common ingredient in extensions of the Standard Model which aim to explain neutrino masses, like for instance in Type I seesaw models, or one of its variants. If the scale of the new Heavy Neutral Leptons (HNLs) is sufficiently low, ...

Proton decay is a smoking gun signature of Grand Unified Theories (GUTs). Searches by Super-Kamiokande have resulted in stringent limits on the GUT symmetry breaking scale. The large-scale multipurpose neutrino experiments DUNE, Hyper-Kamiokande and JUNO will either dis...

FASER$\nu$ is a newly proposed detector whose main mission is to detect neutrino flux from the collision of the proton beams at the ATLAS Interaction Point (IP) during the run III of the LHC in 2021-2023. We show that this detector can also test certain beyond standard ...

The MiniBooNE low-energy excess is a longstanding problem which has received further confirmation recently with a reanalysis using newly collected data, with the anomaly now at the $4.8\sigma$ level. In this letter we propose a novel explanation which advocates a low-en...

In leptonic flavour models with discrete flavour symmetries, couplings between flavons and leptons can result in special flavour structures after they gain vacuum expectation values. At the same time, they can also contribute to the other lepton-flavour-violating proces...

Comment: Discussion extended, KOTO explanation removed and benchmark points updated. Otherwise, conclusions unchanged. 18 pages, 2 figures, 5 tables

We present the first calculation of the one-loop corrections to the triple Higgs coupling in the framework of a simplified 3+1 Dirac neutrino model, that is three light neutrinos plus one heavy neutrino embedded in the Standard Model (SM). The triple Higgs coupling is a...

There is a robust signal for a 511 keV photon line from the galactic center which may originate from the annihilation of dark matter pair with mass of a few MeV to electron and positron. To avoid the bounds from delayed recombination and from the absence of the line fro...