Particle physics today faces the challenge of explaining the mystery of dark matter, the origin
of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent …

With the establishment and maturation of the experimental programs searching for new
physics with sizeable couplings at the LHC, there is an increasing interest in the broader …

The existence of nonzero neutrino masses points to the likely existence of multiple Standard
Model neutral fermions. When such states are heavy enough that they cannot be produced …

Rare meson decays are among the most sensitive probes of both heavy and light new
physics. Among them, new physics searches using kaons benefit from their small total decay …

At the dawn of a new decade, particle physics faces the challenge of explaining the mystery
of dark matter, the origin of matter over antimatter in the Universe, the apparent fine-tuning of …

The NA62 experiment at CERN reports searches for K+→ μ+ N and K+→ μ+ ν X decays,
where N and X are massive invisible particles, using the 2016–2018 data set. The N particle …

We present an overview of searches for violation of lepton flavor universality with a focus on
low energy precision probes using π, K, τ, and nuclear beta decays. We review the current …

We for the first time map the range of active-sterile neutrino mixing angles in which
leptogenesis is possible in the type I seesaw model with three heavy neutrinos with …

Right-handed neutrinos offer an elegant solution to two well-established phenomena
beyond the Standard Model (SM)—masses and oscillations of neutrinos, as well as the …

We constrain the lifetime of thermally produced heavy neutral leptons (HNLs) from big bang
nucleosynthesis. We show that even a small fraction of mesons present in the primeval …