The recent direct detection of neutrinos at the LHC has opened a new window on high-energy particle physics and highlighted the potential of forward physics for groundbreaking discoveries. In the last year, the physics case for forward physics has continued to grow, and there has been extensive work on defining the Forward Physics Facility and its experiments to realize this physics potential in a timely and cost-effective manner. Following a 2-page Executive Summary, we first present the status of the FPF, beginning with the FPF’s unique potential to shed light on dark matter, new particles, neutrino physics, QCD, and astroparticle physics. We then summarize the current designs for the Facility and its experiments, FASER2, FASER $$\nu $$ 2, FORMOSA, and FLArE.

Poland

Jyotismita Adhikary

United States

Luis Anchordoqui

Japan

Switzerland

Akitaka Ariga

Tomoko Ariga

United Kingdom

Alan Barr

Brian Batell

Jianming Bian

Jamie Boyd

Matthew Citron

Albert Roeck

Milind Diwan

Jonathan Feng

Christopher Hill

Yu Jeong

Germany

Felix Kling

Steven Linden

Toni Mäkelä

Kostas Mavrokoridis

Josh McFayden

Hidetoshi Otono

Netherlands

Juan Rojo

Dennis Soldin

Anna Stasto

Sebastian Trojanowski

Matteo Vicenzi

Wenjie Wu

Scientific program for the Forward Physics Facility

The discovery of non-zero neutrino masses and mixings that the Standard Model (SM) cannot accommodate opens up the possibility of the existence of Heavy Neutral Leptons (HNLs). In minimal models, the HNL production and decay are controlled by SM interactions and the mixing between HNLs and the active neutrino and typically result in relatively long lifetimes if the masses are in the MeV–GeV range. We have studied the physics case and technical feasibility for a dedicated HNL search using the NuMI beam at an ICARUS-like detector. Our analysis demonstrates that the constraints on the mixing of the HNL as a function of its mass for an ICARUS-like detector with NuMI beam are highly competitive with the limits obtained from present experiments.

India

Animesh Chatterjee

Spain

Josu Hernandez-Garcia

Heavy neutral lepton searches at an ICARUS-like detector using NuMI beam

Beam dump experiments proposed at the SPS are perfectly suited to explore the parameter space of models with long-lived particles, thanks to the combination of a large intensity with a high proton beam energy. In this paper, we study how the exploration power may be augmented further by installing a detector based on liquid argon time projection chamber technology. In particular, we consider several signatures of new physics particles that may be uniquely searched for with such a detector, including double bang events with heavy neutral leptons, inelastic light dark matter, and millicharged particles.

Martina Ferrillo

Maksym Ovchynnikov

CERN

Filippo Resnati

Improving the potential of BDF@SPS to search for new physics with liquid argon time projection chambers

The search for relativistic scattering signals of cosmogenic light dark matter at terrestrial detectors has received increasing attention as an alternative approach to probe dark-sector physics. Large-volume neutrino experiments are well motivated for searches of dark matter that interacts very weakly with Standard Model particles and/or that exhibits a small incoming flux. We perform a dedicated signal sensitivity study for a detector similar to the one proposed by the DUNE Collaboration for cosmogenic dark-matter signals resulting from a non-minimal multi-particle dark-sector scenario. The liquid argon time projection chamber technology adopted for the DUNE detectors is particularly suited for searching for complicated signatures owing to good measurement resolution and particle identification, as well as dE/dx measurements to recognize merged tracks. Taking inelastic boosted dark matter as our benchmark scenario that allows for multiple visible particles in the final state, we demonstrate that the DUNE far detectors have a great potential for probing scattering signals induced by relativistic light dark matter. Detector effects and backgrounds have been estimated and taken into account. Model-dependent and model-independent expected sensitivity limits for a DUNE-like detector are presented.

Doojin Kim

Italy

Zahra Moghaddam

South Korea

Jong-Chul Park

Seodong Shin

Leigh Whitehead

Probing energetic light dark matter with multi-particle tracks signatures at DUNE

We propose a systematic programme to search for long-lived neutral particle signatures through a minimal set of displaced searches (dMETs). Our approach is to extend the well-established dark matter simplified models to include displaced vertices. The dark matter simplified models are used to describe the primary production vertex. A displaced secondary vertex, characterised by the mass of the long-lived particle and its lifetime, is added for the displaced signature. We show how these models can be motivated by, and mapped onto, complete models such as gauge-mediated SUSY breaking and models of neutral naturalness. We also outline how this approach may be used to extend other simplified models to incorporate displaced signatures and to characterise searches for long-lived charged particles. Displaced vertices are a striking signature which is often virtually background free, and thus provide an excellent target for the high-luminosity run of the Large Hadron Collider. The proposed models and searches provide a first step towards a systematic broadening of the displaced dark matter search programme.