Observation of Collider Neutrinos without Final State Muons with the SND@LHC Experiment

Area of Science:

• High Energy Physics
• Particle Physics
• Neutrino Physics

Background:

• Neutrino interactions are fundamental to understanding particle physics.
• Detecting these interactions, especially rare types, is crucial for probing beyond the Standard Model physics.
• The SND@LHC experiment is designed to detect particles produced in high-energy collisions.

Purpose of the Study:

• To report the observation of neutrino interactions lacking final-state muons at the LHC.
• To characterize these interactions using data from proton-proton collisions.
• To assess the significance of the observed events.

Main Methods:

• Analysis of proton-proton collision data collected by the SND@LHC detector at sqrt[s]=13.6 TeV.
• Selection of events consistent with neutrino interactions without reconstructed final-state muons.
• Estimation of background contributions from Standard Model processes.

Main Results:

• Observation of 9 candidate events for neutrino interactions without final-state muons.
• A statistical significance of 6.4σ was achieved for the observation.
• The selected sample is dominated by neutral-current and electron neutrino charged-current interactions.

Conclusions:

• The observation provides direct evidence of neutrino interactions occurring within the detector at the LHC.
• This finding validates the capabilities of the SND@LHC experiment in detecting such rare events.
• Further studies can leverage this observation to explore neutrino properties and interactions at high energies.