First Direct Observation of Collider Neutrinos with FASER at the LHC.

Area of Science:

• Particle Physics
• High-Energy Physics
• Collider Physics

Background:

• Neutrino interactions are fundamental to understanding particle physics but are challenging to detect.
• Previous observations relied on indirect methods or lower-energy experiments.

Purpose of the Study:

• To report the first direct observation of neutrino interactions at a particle collider.
• To characterize these interactions using data from the Large Hadron Collider.

Main Methods:

• Utilized the FASER detector at the Large Hadron Collider with a 13.6 TeV center-of-mass energy pp collision dataset.
• Identified neutrino candidate events by requiring tracks consistent with muon neutrino charged-current interactions that traversed the detector.

Main Results:

• Observed 153 neutrino interactions with a statistical significance of 16 standard deviations.
• Detected both neutrinos and anti-neutrinos with incident energies significantly above 200 GeV.
• Event characteristics align with expected secondary particle production and spatial distribution.

Conclusions:

• This study provides the first direct evidence of neutrino interactions at a collider.
• The findings open new avenues for studying neutrino properties and interactions at unprecedented energies.