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 …

We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a
comprehensive survey of standard model (SM) extensions. LLPs are a common prediction of …

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large
number of particles along the beam collision axis, outside of the acceptance of existing LHC …

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 …

Searches for long-lived particles (LLPs) are among the most promising avenues for
discovering physics beyond the Standard Model at the Large Hadron Collider (LHC) …

A bstract The problems of neutrino masses, matter-antimatter asymmetry, and dark matter
could be successfully addressed by postulating right-handed neutrinos with Majorana …

Despite decades of attempts to reveal its flaws, the Standard Model of particle physics (SM)
has withstood all experimental tests and its predictions are in excellent agreement with data …

A search for heavy neutral lepton (N) production in K+→ e+ N decays using the data sample
collected by the NA62 experiment at CERN in 2017–2018 is reported. Upper limits of the …

A bstract Heavy Neutral Leptons (HNLs) are hypothetical particles predicted by many
extensions of the Standard Model. These particles can, among other things, explain the …

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 …