A First Determination of the LHC Neutrino Fluxes from FASER Data

Fuente: arXiv
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Main Authors: John, Jukka, Kling, Felix, Koorn, Jelle, Krack, Peter, Rojo, Juan
Format: Preprint
Published: 2025
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author John, Jukka
Kling, Felix
Koorn, Jelle
Krack, Peter
Rojo, Juan
author_facet John, Jukka
Kling, Felix
Koorn, Jelle
Krack, Peter
Rojo, Juan
contents The detection of TeV neutrinos from the LHC by the far-forward detectors FASER and SND@LHC enables a plethora of novel physics opportunities. Among these, the measurement of the flavour, energy, and rapidity dependence of the LHC forward neutrino fluxes provides unique constraints on theoretical predictions of forward particle production in hadronic collisions. We demonstrate that neutrino event yield measurements at FASER from Run 3 and at its HL-LHC upgrades enable a theory-agnostic extraction of the LHC forward neutrino fluxes. We exploit the equivalence of the problem with the determination of parton distributions from deep-inelastic structure functions to apply the NNPDF approach, based on machine learning regression and the Monte Carlo replica method, to LHC neutrino fluxes. The resulting NN$ν$flux methodology is validated through closure tests and applied to a first extraction of the LHC muon neutrino flux from the FASER 2024 data. We show how NN$ν$flux can discriminate between event generators of forward hadron production; scrutinize a possible intrinsic charm component in the proton; and constrain BSM scenarios with enhanced decays of neutral hadrons into neutrinos.
format Preprint
id arxiv_https___arxiv_org_abs_2507_06022
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A First Determination of the LHC Neutrino Fluxes from FASER Data
John, Jukka
Kling, Felix
Koorn, Jelle
Krack, Peter
Rojo, Juan
High Energy Physics - Phenomenology
High Energy Physics - Experiment
The detection of TeV neutrinos from the LHC by the far-forward detectors FASER and SND@LHC enables a plethora of novel physics opportunities. Among these, the measurement of the flavour, energy, and rapidity dependence of the LHC forward neutrino fluxes provides unique constraints on theoretical predictions of forward particle production in hadronic collisions. We demonstrate that neutrino event yield measurements at FASER from Run 3 and at its HL-LHC upgrades enable a theory-agnostic extraction of the LHC forward neutrino fluxes. We exploit the equivalence of the problem with the determination of parton distributions from deep-inelastic structure functions to apply the NNPDF approach, based on machine learning regression and the Monte Carlo replica method, to LHC neutrino fluxes. The resulting NN$ν$flux methodology is validated through closure tests and applied to a first extraction of the LHC muon neutrino flux from the FASER 2024 data. We show how NN$ν$flux can discriminate between event generators of forward hadron production; scrutinize a possible intrinsic charm component in the proton; and constrain BSM scenarios with enhanced decays of neutral hadrons into neutrinos.
title A First Determination of the LHC Neutrino Fluxes from FASER Data
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2507.06022