SND@LHC: The Scattering and Neutrino Detector at the LHC

SND@LHC is a compact and stand-alone experiment designed to perform measurements with neutrinos produced at the LHC in the pseudo-rapidity region of ${7.2 < \eta < 8.4}$. The experiment is located 480 m downstream of the ATLAS interaction point, in the TI18 tunnel. The detector is composed of a hybrid system based on an 830 kg target made of tungsten plates, interleaved with emulsion and electronic trackers, also acting as an electromagnetic calorimeter, and followed by a hadronic calorimeter and a muon identification system. The detector is able to distinguish interactions of all three neutrino flavours, which allows probing the physics of heavy flavour production at the LHC in the very forward region. This region is of particular interest for future circular colliders and for very high energy astrophysical neutrino experiments. The detector is also able to search for the scattering of Feebly Interacting Particles. In its first phase, the detector will operate throughout LHC Run 3 and collect a total of 250 $\text{fb}^{-1}$

A facility to search for hidden particles at the CERN SPS: the SHiP physics case

Theoretical Physic

The forward physics facility at the high-luminosity LHC

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 experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential

Observation of collider muon neutrinos with the SND@LHC experiment

We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A data set of proton-proton collisions at $\sqrt{s} = 13.6\,$TeV collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of 36.8$\,\rm{fb}^{-1}$. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudo-rapidity region of 7.2 < \eta < 8.4, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 $\nu_\mu$ interaction candidate events remain with an estimated background of 0.076 events, yielding a significance of seven standard deviations for the observed $\nu_\mu$ signal

A facility to Search for Hidden Particles (SHiP) at the CERN SPS

A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation

Science with the Cherenkov Telescope Array

The Cherenkov Telescope Array, CTA, will be the major global observatory forvery high energy gamma-ray astronomy over the next decade and beyond. Thescientific potential of CTA is extremely broad: from understanding the role ofrelativistic cosmic particles to the search for dark matter. CTA is an explorerof the extreme universe, probing environments from the immediate neighbourhoodof black holes to cosmic voids on the largest scales. Covering a huge range inphoton energy from 20 GeV to 300 TeV, CTA will improve on all aspects ofperformance with respect to current instruments. The observatory will operate arrays on sites in both hemispheres to providefull sky coverage and will hence maximize the potential for the rarestphenomena such as very nearby supernovae, gamma-ray bursts or gravitationalwave transients. With 99 telescopes on the southern site and 19 telescopes onthe northern site, flexible operation will be possible, with sub-arraysavailable for specific tasks. CTA will have important synergies with many ofthe new generation of major astronomical and astroparticle observatories.Multi-wavelength and multi-messenger approaches combining CTA data with thosefrom other instruments will lead to a deeper understanding of the broad-bandnon-thermal properties of target sources. The CTA Observatory will be operated as an open, proposal-driven observatory,with all data available on a public archive after a pre-defined proprietaryperiod. Scientists from institutions worldwide have combined together to formthe CTA Consortium. This Consortium has prepared a proposal for a CoreProgramme of highly motivated observations. The programme, encompassingapproximately 40% of the available observing time over the first ten years ofCTA operation, is made up of individual Key Science Projects (KSPs), which arepresented in this document