Ghostly Interactions: LHC Detects First High-Energy Neutrino Collisions

The Large Hadron Collider (LHC) at CERN has achieved a groundbreaking feat, providing the first direct measurement of electron- and muon-neutrino interaction rates. These interactions, involving the elusive "ghost particles" known as neutrinos, were observed at the highest neutrino energies ever recorded from a human-generated source, offering a potential key to unlocking some of the universe's most enduring mysteries.

The findings, published in *Physical Review Letters*, mark a significant advancement in our understanding of neutrinos and their role in the fundamental structure of the universe. Neutrinos, ubiquitous throughout the cosmos, are fundamental particles that interact incredibly weakly with matter, earning them the nickname "ghost particles". This characteristic makes them notoriously difficult to detect, as they typically pass through matter without leaving a trace.

The LHC, a colossal particle accelerator located on the Swiss-French border, provided the ideal environment for this research. The experiment, conducted by the FASER (Forward Search Experiment) collaboration, exploited the high-energy proton-proton collisions generated within the LHC to produce high-energy neutrinos. These neutrinos were then detected using the FASERν detector, a sophisticated device weighing a tonne and composed of 730 layers of alternating tungsten plates and emulsion films.

The FASERν detector's unique design allows for precise tracking of charged particle tracks produced by neutrino interactions. This enabled the researchers to identify electron and muon charged-current (CC) neutrino interactions and measure neutrino interaction cross-sections – the probability of a neutrino interacting with a target particle – in an energy range previously unexplored, the TeV (teraelectronvolt) energy range.

The team focused on identifying electrons or muons with energies exceeding 200 GeV (gigaelectronvolt). This resulted in the first-ever detection of neutrinos in the TeV energy range, a significant achievement that aligns with predictions made by the Standard Model of particle physics.

The discovery has far-reaching implications for the field of particle physics. It represents the first physics result on neutrinos from a particle collider, a pivotal breakthrough that could reshape the landscape of large-scale experimental research in the field. The observed neutrino interactions could provide crucial insights into fundamental questions about the universe, including the intriguing imbalance between matter and antimatter.

This research marks a pivotal moment in our understanding of the elusive neutrino. The findings not only provide valuable data on neutrino interactions but also pave the way for further exploration of these enigmatic particles, potentially leading to groundbreaking discoveries that could reshape our comprehension of the universe and its fundamental constituents.