Detecting and Studying High-Energy Collider Neutrinos with FASER at the LHC

6 August 2019

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e-print: arXiv:1908.02310 pdf from arXiv
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Abstract
Neutrinos are copiously produced at particle colliders, but no collider neutrino has ever been detected. Colliders, and particularly hadron colliders, produce both neutrinos and anti-neutrinos of all flavors at very high energies, and they are therefore highly complementary to those from other sources. FASER, the recently approved Forward Search Experiment at the Large Hadron Collider, is ideally located to provide the first detection and study of collider neutrinos. We investigate the prospects for neutrino studies of a proposed component of FASER, FASERν, a 25 cm × 25 cm × 1.35 m emulsion detector to be placed directly in front of the FASER spectrometer in tunnel TI12. FASERν consists of 1000 layers of emulsion films interleaved with 1-mm-thick tungsten plates, with a total tungsten target mass of 1.2 tons. We estimate the neutrino fluxes and interaction rates at FASERν, describe the FASERν detector, and analyze the characteristics of the signals and primary backgrounds. For an integrated luminosity of 150 fb−1 to be collected during Run 3 of the 14 TeV Large Hadron Collider from 2021-23, and assuming standard model cross sections, approximately 1300 νe, 20,000 νμ, and 20 ντ will interact in FASERν, with mean energies of 600 GeV to 1 TeV, depending on the flavor. With such rates and energies, FASER will measure neutrino cross sections at energies where they are currently unconstrained, will bound models of forward particle production, and could open a new window on physics beyond the standard model.
Figures
Figure 01:
Schematic view of the far-forward region downstream of ATLAS. Upper panel: FASER is located 480 m downstream of ATLAS along the beam collision axis (dotted line) after the main LHC tunnel curves away. Lower left panel: High-energy particles produced at the IP in the far-forward direction. Charged particles (solid lines) are deflected by LHC quadrupole (Q) and dipole (D) magnets. Neutral hadrons are absorbed by either the TAS front quadrupole absorber or by the TAN neutral particle absorber. Neutrinos (dashed lines) are produced either promptly or displaced and pass through the LHC infrastructure without interacting. Note the extreme difference in horizontal and vertical scales. Lower right panel: Neutrinos may then travel ∼ 480 m further downstream into tunnel TI12 and interact in FASERν, which is located at the front of the FASER detector. f.

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Figure 02a:
View of FASER, including the FASERν detector, in tunnel TI12, 480 m downstream from the ATLAS IP along the beam collision axis. The FASERν detector is a 25 cm × 25 cm × 1.35 m emulsion detector, consisting of 1000 layers of emulsion films interleaved with 1-mm-thick tungsten plates, with a total tungsten target mass of 1.2 tons. It is located at the front of FASER in a narrow trench being excavated specifically to house it. f.

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Figure 02b:
View of FASER, including the FASERν detector, in tunnel TI12, 480 m downstream from the ATLAS IP along the beam collision axis. The FASERν detector is a 25 cm × 25 cm × 1.35 m emulsion detector, consisting of 1000 layers of emulsion films interleaved with 1-mm-thick tungsten plates, with a total tungsten target mass of 1.2 tons. It is located at the front of FASER in a narrow trench being excavated specifically to house it. f.

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Figure 03:
Existing constraints on νN CC scattering cross sections, where N refers to an isoscalar nucleon in the target, and the expected energy spectra of neutrinos that interact in FASERν. For all three flavors, the FASER energy spectra are peaked at energies that are currently unconstrained. Left, νe constraints: Bounds from E53 [37] and DONuT [38]. The bounds from E53 on σνe / σνμ and σanti-νe / σanti-νμ are multiplied by the current values of σνμ and σanti-νμ, respectively. Center, νμ constraints: Bounds from accelerator neutrinos at energies below 360 GeV [40] and from IceCube at energies above 6.3 TeV [41,42]. From Ref. [41]. Right, ντ constraints: The constraint on the energy-independent part of the cross section C from DONuT [38] is shown (see text). DONuT's main systematic uncertainty from the Ds differential production cross section is not included. For OPERA [43], SuperKamiokande [44], and IceCube [45], we indicate the energy ranges of ντ cross section results, but not the measured cross sections themselves (see text). f.

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Figure 04:
The estimated number of neutrinos that pass through the 25 cm × 25 cm transverse area of FASERν, assuming an integrated luminosity of 150 fb-1 for Run 3 at the 14 TeV LHC. The event rates are for electron (left), muon (center), and tau (right) neutrinos (upper) and anti-neutrinos (lower). The shaded bands indicate the range of predictions from the different MC generators listed in Table I, and the solid contours are the average results of these MC generators. f.

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Figure 05a:
Left: The ν N (solid) and anti-ν N (dashed) DIS cross sections, where N is a tungsten nucleus, calculated with the NNPDF3.1 parton distribution functions [75]. Center: The energy spectrum of neutrinos with CC interactions in a 1-ton tungsten detector with dimensions 25 cm × 25 cm × 1 m centered on the beam collision axis at the FASER location. Right: The neutrino interaction rate per unit area normalized to the prediction at the beam collision axis for a detector with large radius. f.

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Figure 05b:
Left: The ν N (solid) and anti-ν N (dashed) DIS cross sections, where N is a tungsten nucleus, calculated with the NNPDF3.1 parton distribution functions [75]. Center: The energy spectrum of neutrinos with CC interactions in a 1-ton tungsten detector with dimensions 25 cm × 25 cm × 1 m centered on the beam collision axis at the FASER location. Right: The neutrino interaction rate per unit area normalized to the prediction at the beam collision axis for a detector with large radius. f.

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Figure 05c:
Left: The ν N (solid) and anti-ν N (dashed) DIS cross sections, where N is a tungsten nucleus, calculated with the NNPDF3.1 parton distribution functions [75]. Center: The energy spectrum of neutrinos with CC interactions in a 1-ton tungsten detector with dimensions 25 cm × 25 cm × 1 m centered on the beam collision axis at the FASER location. Right: The neutrino interaction rate per unit area normalized to the prediction at the beam collision axis for a detector with large radius. f.

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Figure 06:
Side view of the FASER and FASERν detectors in side tunnel TI12. f.

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Figure 07:
Schematic of the detector structure and the topology of various neutrino signal events that can be seen in the detector. f.

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Figure 08a:
Topological and kinematic features of neutrino interactions as a function of the simulated neutrino energy ("MC truth"). As an example, the distributions of νμ CC interactions are shown. Upper panels: The multiplicity of charged particle tracks and γ rays with momentum ptr > 0.3 GeV and angle θ<45° relative to the neutrino direction. Middle left: Inverse of lepton slope. Middle right: Inverse of median of charged particle slopes. Lower left: Lepton momentum. Lower right: Sum of charged hadron momenta. f.

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Figure 08b:
Topological and kinematic features of neutrino interactions as a function of the simulated neutrino energy ("MC truth"). As an example, the distributions of νμ CC interactions are shown. Upper panels: The multiplicity of charged particle tracks and γ rays with momentum ptr > 0.3 GeV and angle θ<45° relative to the neutrino direction. Middle left: Inverse of lepton slope. Middle right: Inverse of median of charged particle slopes. Lower left: Lepton momentum. Lower right: Sum of charged hadron momenta. f.

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Figure 08c:
Topological and kinematic features of neutrino interactions as a function of the simulated neutrino energy ("MC truth"). As an example, the distributions of νμ CC interactions are shown. Upper panels: The multiplicity of charged particle tracks and γ rays with momentum ptr > 0.3 GeV and angle θ<45° relative to the neutrino direction. Middle left: Inverse of lepton slope. Middle right: Inverse of median of charged particle slopes. Lower left: Lepton momentum. Lower right: Sum of charged hadron momenta. f.

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Figure 08d:
Topological and kinematic features of neutrino interactions as a function of the simulated neutrino energy ("MC truth"). As an example, the distributions of νμ CC interactions are shown. Upper panels: The multiplicity of charged particle tracks and γ rays with momentum ptr > 0.3 GeV and angle θ<45$deg; relative to the neutrino direction. Middle left: Inverse of lepton slope. Middle right: Inverse of median of charged particle slopes. Lower left: Lepton momentum. Lower right: Sum of charged hadron momenta. f.

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Figure 08e:
Topological and kinematic features of neutrino interactions as a function of the simulated neutrino energy ("MC truth"). As an example, the distributions of νμ CC interactions are shown. Upper panels: The multiplicity of charged particle tracks and γ rays with momentum ptr > 0.3 GeV and angle θ<45° relative to the neutrino direction. Middle left: Inverse of lepton slope. Middle right: Inverse of median of charged particle slopes. Lower left: Lepton momentum. Lower right: Sum of charged hadron momenta. f.

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Figure 08f:
Topological and kinematic features of neutrino interactions as a function of the simulated neutrino energy ("MC truth"). As an example, the distributions of νμ CC interactions are shown. Upper panels: The multiplicity of charged particle tracks and γ rays with momentum ptr > 0.3 GeV and angle θ<45$deg; relative to the neutrino direction. Middle left: Inverse of lepton slope. Middle right: Inverse of median of charged particle slopes. Lower left: Lepton momentum. Lower right: Sum of charged hadron momenta. f.

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Figure 09a:
Left: Vertex detection efficiency after requiring at least 5 charged particles at a neutrino interaction vertex (CC and NC inclusive). Only the statistical uncertainties of the generated Genie samples are shown. Right: The distribution of events in the (τ flight length, kink angle) plane, where the events are ντ CC interactions in FASERν that produce tau leptons that decay through 1-prong decays. The black hatched region is excluded by the cuts described in the text; requiring the event to be in the unhatched region leads to a 75% τ detection efficiency. f.

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Figure 09b:
Left: Vertex detection efficiency after requiring at least 5 charged particles at a neutrino interaction vertex (CC and NC inclusive). Only the statistical uncertainties of the generated Genie samples are shown. Right: The distribution of events in the (τ flight length, kink angle) plane, where the events are ντ CC interactions in FASERν that produce tau leptons that decay through 1-prong decays. The black hatched region is excluded by the cuts described in the text; requiring the event to be in the unhatched region leads to a 75% τ detection efficiency. f.

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Figure 10a:
Left: Schematic of the MCS measurement. Center: MC study of momentum reconstruction with the MCS method, assuming a position resolution of σpos = 0.4 μm and a track length of 100 1-mm-thick tungsten plates. Events with PMCS>7 TeV are shown at PMCS = 7 TeV so that they can be seen in the figure. On the black line, Ptrue = PMCS. Right: The largest momentum for which the MCS method is applicable as a function of position resolution. The largest momentum is defined to be the momentum for which 90% of the particles' momenta are reconstructed to have PMCS < 7 TeV. f.

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Figure 10b:
Left: Schematic of the MCS measurement. Center: MC study of momentum reconstruction with the MCS method, assuming a position resolution of σpos = 0.4 μm and a track length of 100 1-mm-thick tungsten plates. Events with PMCS>7 TeV are shown at PMCS = 7 TeV so that they can be seen in the figure. On the black line, Ptrue = PMCS. Right: The largest momentum for which the MCS method is applicable as a function of position resolution. The largest momentum is defined to be the momentum for which 90% of the particles' momenta are reconstructed to have PMCS < 7 TeV. f.

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Figure 10c:
Left: Schematic of the MCS measurement. Center: MC study of momentum reconstruction with the MCS method, assuming a position resolution of σpos = 0.4 μm and a track length of 100 1-mm-thick tungsten plates. Events with PMCS>7 TeV are shown at PMCS = 7 TeV so that they can be seen in the figure. On the black line, Ptrue = PMCS. Right: The largest momentum for which the MCS method is applicable as a function of position resolution. The largest momentum is defined to be the momentum for which 90% of the particles' momenta are reconstructed to have PMCS < 7 TeV. f.

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Figure 11:
Left: Neutrino energy and sum of visible energy (momentum of charged particles and energy of electromagnetic showers) for νμ CC samples with at least five charged tracks ntr ≥ 5, with smearing (MC). The effect of the 7 TeV upper limit used in the MCS method is visible near the top of the figure. Center: Neutrino energy reconstruction based on the ANN. The observables listed in Table III are used as the inputs for the ANN algorithm. Right: Δ EνANN / Eνtrue for the same sample. An energy resolution of 30% (RMS) was obtained for the energies of interest. f.

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Figure 12:
Plan of the detector upgrade to couple FASERν to the FASER main detector. The components include the FASERν emulsion detector (black), scintillators (gray), tracking layers (blue), magnets (red), and electromagnetic calorimeter (purple). f.

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Figure 13a:
Left: Angular distributions of charged particles measured by the emulsion films with and without tungsten plates, corresponding to energy cutoffs of about 1 GeV and 50 MeV, due to multiple Coulomb scattering, respectively. Right: Fluxes of positive and negative muons at the FASERν location predicted by the FLUKA simulations and normalized to an instantaneous luminosity of 2 × 1034 cm-2 s-1. From [34]. f.

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Figure 13b:
Left: Angular distributions of charged particles measured by the emulsion films with and without tungsten plates, corresponding to energy cutoffs of about 1 GeV and 50 MeV, due to multiple Coulomb scattering, respectively. Right: Fluxes of positive and negative muons at the FASERν location predicted by the FLUKA simulations and normalized to an instantaneous luminosity of 2 × 1034 cm-2 s-1. From [34]. f.

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Figure 14a:
Distributions of negative (left) and positive (right) muons crossing the tunnel TI18, which is in a symmetric position on the opposite side of the ATLAS IP with respect to FASERν. The position of FASERν in the center of the coordinate system is indicated by a black square. From Ref. [34]. f.

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Figure 14b:
Distributions of negative (left) and positive (right) muons crossing the tunnel TI18, which is in a symmetric position on the opposite side of the ATLAS IP with respect to FASERν. The position of FASERν in the center of the coordinate system is indicated by a black square. From Ref. [34]. f.

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Figure 15a:
The energy and angular distributions of neutral hadrons that are produced by negative muon interactions and pass through FASERν in Run 3. Left: The energy spectrum of neutral hadrons produced in the rock in front of FASER and produced within the detector (black) as well as neutrinos interacting with the detector: νe (red), νμ (blue) and ντ (green). Right: The angular distribution of neutral hadrons produced in the rock in front of FASERν and passing into the detector for energies E>10 GeV (orange) and E>100 GeV (blue). The angle is given with respect to the beam collision axis. The estimated angular resolution of a ∼ 100 GeV hadron is about 10 mrad, as indicated by the vertical dashed line. f.

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Figure 15b:
The energy and angular distributions of neutral hadrons that are produced by negative muon interactions and pass through FASERν in Run 3. Left: The energy spectrum of neutral hadrons produced in the rock in front of FASER and produced within the detector (black) as well as neutrinos interacting with the detector: νe (red), νμ (blue) and ντ (green). Right: The angular distribution of neutral hadrons produced in the rock in front of FASERν and passing into the detector for energies E>10 GeV (orange) and E>100 GeV (blue). The angle is given with respect to the beam collision axis. The estimated angular resolution of a ∼ 100 GeV hadron is about 10 mrad, as indicated by the vertical dashed line. f.

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Figure 16a:
Left: Distribution of the angle φ between the HMP and the vectorial sum of momenta of all tracks, in the two-dimensional transverse plane, and the momentum fraction of the HMP, for νμ CC (blue) and NC (red) interactions. The MC sample is generated by Genie with the FASER νμ spectrum, and the same smearing as in Sec. IV C is applied. Right: Same plot for neutral hadron backgrounds. f.

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Figure 16b:
Left: Distribution of the angle φ between the HMP and the vectorial sum of momenta of all tracks, in the two-dimensional transverse plane, and the momentum fraction of the HMP, for νμ CC (blue) and NC (red) interactions. The MC sample is generated by Genie with the FASER νμ spectrum, and the same smearing as in Sec. IV C is applied. Right: Same plot for neutral hadron backgrounds. f.

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Figure 17a:
Left: The 30 kg pilot neutrino detector that was installed in the TI18 tunnel in 2018. It collected 12.5 fb-1 of data. Center: Reconstructed tracks in 2 mm × 2 mm × 10 emulsion films. About 13,000 tracks were observed, corresponding to about 3 × 105 tracks/sicm2. Right: A vertex found in the detector with no incoming charged track. The vertex axis is compatible with the beam direction. The red scale bars in the center and right figures are 1000 μm and 500 μm long, respectively. f.

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Figure 17b:
Left: The 30 kg pilot neutrino detector that was installed in the TI18 tunnel in 2018. It collected 12.5 fb-1 of data. Center: Reconstructed tracks in 2 mm × 2 mm × 10 emulsion films. About 13,000 tracks were observed, corresponding to about 3 × 105 tracks/sicm2. Right: A vertex found in the detector with no incoming charged track. The vertex axis is compatible with the beam direction. The red scale bars in the center and right figures are 1000 μm and 500 μm long, respectively. f.

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Figure 17c:
Left: The 30 kg pilot neutrino detector that was installed in the TI18 tunnel in 2018. It collected 12.5 fb-1 of data. Center: Reconstructed tracks in 2 mm × 2 mm × 10 emulsion films. About 13,000 tracks were observed, corresponding to about 3 × 105 tracks/sicm2. Right: A vertex found in the detector with no incoming charged track. The vertex axis is compatible with the beam direction. The red scale bars in the center and right figures are 1000 μm and 500 μm long, respectively. f.

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Figure 18a:
FASERν's estimated ν-nucleon CC cross section sensitivity for νe (left), νμ (center), and ντ (right) at Run 3 of the 14 TeV LHC with an integrated luminosity of 150 fb-1 collected from 2021-23. Existing constraints [40] are shown in gray for σν and σanti-ν at accelerator experiments and for their weighted average at IceCube. The black dashed curve is the theoretical prediction for the average DIS cross section per tungsten-weighted nucleon, as introduced in Eq. (4). The solid error bars correspond to statistical uncertainties, the shaded regions show uncertainties from neutrino production rate corresponding to the range of predictions obtained from different MC generators, and the dashed error bars show their combination. Here we include the geometrical acceptance, vertex detection efficiency and lepton identification efficiency as discussed in the text. f.

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Figure 18b:
FASERν's estimated ν-nucleon CC cross section sensitivity for νe (left), νμ (center), and ντ (right) at Run 3 of the 14 TeV LHC with an integrated luminosity of 150 fb-1 collected from 2021-23. Existing constraints [40] are shown in gray for σν and σanti-ν at accelerator experiments and for their weighted average at IceCube. The black dashed curve is the theoretical prediction for the average DIS cross section per tungsten-weighted nucleon, as introduced in Eq. (4). The solid error bars correspond to statistical uncertainties, the shaded regions show uncertainties from neutrino production rate corresponding to the range of predictions obtained from different MC generators, and the dashed error bars show their combination. Here we include the geometrical acceptance, vertex detection efficiency and lepton identification efficiency as discussed in the text. f.

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Figure 18c:
FASERν's estimated ν-nucleon CC cross section sensitivity for νe (left), νμ (center), and ντ (right) at Run 3 of the 14 TeV LHC with an integrated luminosity of 150 fb-1 collected from 2021-23. Existing constraints [40] are shown in gray for σν and σanti-ν at accelerator experiments and for their weighted average at IceCube. The black dashed curve is the theoretical prediction for the average DIS cross section per tungsten-weighted nucleon, as introduced in Eq. (4). The solid error bars correspond to statistical uncertainties, the shaded regions show uncertainties from neutrino production rate corresponding to the range of predictions obtained from different MC generators, and the dashed error bars show their combination. Here we include the geometrical acceptance, vertex detection efficiency and lepton identification efficiency as discussed in the text. f.

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Figure 19a:
Left: Relative charm hadron production rate in neutrino interactions. The solid black curve shows the expected fraction of charm-associated neutrino interactions in the FASERν detector as a function of neutrino energy, obtained with Pythia 8. The dashed blue and orange curve further separate the fraction into charged and neutral charm hadrons, respectively. The gray error bars show the results of previous measurements obtained in the CHORUS and E531 experiments [129]. Note that these results cannot be directly compared due to the different neutrino vs. anti-neutrino beam compositions and the different neutron fractions of the target material for CHORUS and FASERν. Right: Electron (solid) and tau (dashed) neutrino interactions in FASERν using different intrinsic charm models in CT14nnlo-IC. f.

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Figure 19b:
Left: Relative charm hadron production rate in neutrino interactions. The solid black curve shows the expected fraction of charm-associated neutrino interactions in the FASERν detector as a function of neutrino energy, obtained with Pythia 8. The dashed blue and orange curve further separate the fraction into charged and neutral charm hadrons, respectively. The gray error bars show the results of previous measurements obtained in the CHORUS and E531 experiments [129]. Note that these results cannot be directly compared due to the different neutrino vs. anti-neutrino beam compositions and the different neutron fractions of the target material for CHORUS and FASERν. Right: Electron (solid) and tau (dashed) neutrino interactions in FASERν using different intrinsic charm models in CT14nnlo-IC. f.

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Figure 20:
Left: Diagrams of purely leptonic (upper) and semi-leptonic (lower) beauty decays. Center: The corresponding neutrino CC interactions with b quark production. In the bottom diagram, perturbative charm quarks contribute to the neutrino interaction. Right: The event topology of ντ CC interactions that produce beauty hadrons. For simplicity, the conjugate diagrams are omitted. f.

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Figure 21:
Upper panel: The νμ disappearance oscillation probability in the SM (blue) and in the presence of a sterile neutrino with Δ m241=1,600 eV2 and |Uμ4|2=0.1 (orange). Lower panel: The expected νμ event rate at FASER in the SM (blue) and in the presence of a sterile neutrino with the same parameters. The statistical and production uncertainties (added in quadrature) are shown in the blue shaded region. The location of the first oscillation minimum is marked with a dotted line. f.

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Figure 22a:
The 95% CL regions of sterile neutrino parameters that will be excluded by FASER assuming different normalization uncertainties. The regions to the right of the black dotted lines are already excluded by previous experiments [148,149,150]. The yellow shaded region in the upper left panel is the preferred region for the Gallium anomaly in the νe disappearance channel [151], and the blue shaded region in the lower center panel is the region preferred by MiniBooNE in the νμ→νe appearance channel [152]. f.

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Figure 22b:
The 95% CL regions of sterile neutrino parameters that will be excluded by FASER assuming different normalization uncertainties. The regions to the right of the black dotted lines are already excluded by previous experiments [148,149,150]. The yellow shaded region in the upper left panel is the preferred region for the Gallium anomaly in the νe disappearance channel [151], and the blue shaded region in the lower center panel is the region preferred by MiniBooNE in the νμ→νe appearance channel [152]. f.

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Figure 22c:
The 95% CL regions of sterile neutrino parameters that will be excluded by FASER assuming different normalization uncertainties. The regions to the right of the black dotted lines are already excluded by previous experiments [148,149,150]. The yellow shaded region in the upper left panel is the preferred region for the Gallium anomaly in the νe disappearance channel [151], and the blue shaded region in the lower center panel is the region preferred by MiniBooNE in the νμ→νe appearance channel [152]. f.

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Figure 22d:
The 95% CL regions of sterile neutrino parameters that will be excluded by FASER assuming different normalization uncertainties. The regions to the right of the black dotted lines are already excluded by previous experiments [148,149,150]. The yellow shaded region in the upper left panel is the preferred region for the Gallium anomaly in the νe disappearance channel [151], and the blue shaded region in the lower center panel is the region preferred by MiniBooNE in the νμ→νe appearance channel [152]. f.

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Figure 22e:
The 95% CL regions of sterile neutrino parameters that will be excluded by FASER assuming different normalization uncertainties. The regions to the right of the black dotted lines are already excluded by previous experiments [148,149,150]. The yellow shaded region in the upper left panel is the preferred region for the Gallium anomaly in the νe disappearance channel [151], and the blue shaded region in the lower center panel is the region preferred by MiniBooNE in the νμ→νe appearance channel [152]. f.

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Figure 22f:
The 95% CL regions of sterile neutrino parameters that will be excluded by FASER assuming different normalization uncertainties. The regions to the right of the black dotted lines are already excluded by previous experiments [148,149,150]. The yellow shaded region in the upper left panel is the preferred region for the Gallium anomaly in the νe disappearance channel [151], and the blue shaded region in the lower center panel is the region preferred by MiniBooNE in the νμ→νe appearance channel [152]. f.

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Tables
Table 01:
Decays considered for the estimate of forward neutrino production. For each type in the first column, we list the considered particles in the second column and the main decay modes contributing to neutrino production in the third column. In the last four columns we show which generators were used to obtain the meson spectra: Epos-Lhc (E) [57], Qgsjet-ii-04 (Q) [58], Sibyll 2.3c (S) [59,60,61,62], and Pythia 8 (P) [64,65], using both the Monash-tune [66] and the minimum bias A2-tune [67]. f.

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Table 02:
The expected number of neutrinos with Eν > 100 GeV interacting through CC processes in FASERν, the expected number of reconstructed vertices in FASERν requiring ntr ≥ 5, and the mean energy of neutrinos that interact in FASERν. Here we assume a benchmark detector made of tungsten with dimensions 25 cm × 25 cm × 1 m at the 14 TeV LHC with an integrated luminosity of L=150 fb-1. Reductions in the number of reconstructed vertices from the geometrical acceptance and lepton identification efficiency have not been included. The uncertainties correspond to the range of predictions obtained from different MC generators. f.

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Table 03:
Inputs for the ANN algorithm. For the momentum estimates using the MCS method, we assume a position resolution of 0.4 μm. For the energy measurement in photon showers we assume an energy resolution of 50%. f.

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Table 04:
The expected number of negative-muon-induced particles passing through FASERν in LHC Run 3, as estimated by a dedicated FLUKA study. In each entry, the first number is the number of particles emerging from the rock in front of FASERν, and the second is the number of particles produced in muon interactions in the tungsten plates in FASERν. 2 × 109 muons are expected to pass through FASERν in Run 3. We note that the statistical uncertainties of the numbers presented in this table can reach even factors of a few, especially for the less abundant neutral hadrons. f.

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