Abstract The Forward Physics Facility (FPF) is a proposal to create a cavern with the space
and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider …

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 present white paper is submitted as part of the “Snowmass” process to help inform the
long-term plans of the United States Department of Energy and the National Science …

We present a new version of the hadron interaction event generator sibyll. While the core
ideas of the model have been preserved, the new version handles the production of baryon …

High-energy cosmic rays are observed indirectly by detecting the extensive air showers
initiated in Earth's atmosphere. The interpretation of these observations relies on accurate …

We review open questions and prospects for progress in ultrahigh-energy cosmic ray
(UHECR) research, based on a series of discussions that took place during the “The High …

We present the first measurement of the fluctuations in the number of muons in extensive air
showers produced by ultrahigh energy cosmic rays. We find that the measured fluctuations …

Multi-messenger astrophysics, a long-anticipated extension to traditional multiwavelength
astronomy, has emerged over the past decade as a distinct discipline providing unique and …

We present a new method for probing the hadronic interaction models at ultrahigh energy
and extracting details about mass composition. This is done using the time profiles of the …