First Measurement of ν_{e} and ν_{μ} Interaction Cross Sections at the LHC with FASER's Emulsion Detector

Area of Science:

• Particle Physics
• High-Energy Physics
• Neutrino Physics

Background:

• The FASER experiment at the Large Hadron Collider (LHC) is designed to detect high-energy neutrinos.
• Understanding neutrino interactions is crucial for particle physics and cosmology.

Purpose of the Study:

• To present the first results on high-energy electron neutrino (ν_{e}) and muon neutrino (ν_{μ}) charged-current interactions.
• To measure neutrino interaction cross sections at unprecedented energies.

Main Methods:

• Analysis of a 128.8 kg subset of the FASERν detector's emulsion-tungsten target.
• Exposure to 9.5 fb⁻¹ of √s = 13.6 TeV proton-proton collision data at the LHC.
• Identification and statistical analysis of neutrino interaction candidate events.

Main Results:

• Observation of four electron neutrino (ν_{e}) and eight muon neutrino (ν_{μ}) candidate events with high statistical significance (5.2σ and 5.7σ, respectively).
• First direct observation of ν_{e} interactions at a particle collider.
• Detection of the highest-energy ν_{e} and ν_{μ} ever recorded from an artificial source.
• Measurement of interaction cross sections per nucleon (σ/E_{ν}) for ν_{e} and ν_{μ} in the 520-1760 GeV range, consistent with Standard Model predictions.

Conclusions:

• The results represent the first direct observation of electron neutrino interactions at a particle collider.
• These measurements provide the first cross-section data for neutrinos in these high-energy ranges.
• The findings validate Standard Model predictions for neutrino interactions at the LHC energies.