Measurement of the multi-TeV neutrino interaction cross-section with IceCube using Earth absorption

Abstract

Neutrinos interact only very weakly, so they are extremely penetrating. The theoretical neutrino-nucleon interaction cross-section, however, increases with increasing neutrino energy, and neutrinos with energies above 40 teraelectronvolts (TeV) are expected to be absorbed as they pass through the Earth. Experimentally, the cross-section has been determined only at the relatively low energies (below 0.4 TeV) that are available at neutrino beams from accelerators. Here we report a measurement of neutrino absorption by the Earth using a sample of 10,784 energetic upward-going neutrino-induced muons. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to a reference sample that follows shorter trajectories. Using a fit to the two-dimensional distribution of muon energy and zenith angle, we determine the neutrino-nucleon interaction cross-section for neutrino energies 6.3-980 TeV, more than an order of magnitude higher than previous measurements. The measured cross-section is about 1.3 times the prediction of the standard model, consistent with the expectations for charged- and neutral-current interactions. We do not observe a large increase in the cross-section with neutrino energy, in contrast with the predictions of some theoretical models, including those invoking more compact spatial dimensions or the production of leptoquarks. This cross-section measurement can be used to set limits on the existence of some hypothesized beyond-standard-model particles, including leptoquarks.

W -boson and trident production in TeV–PeV neutrino observatories

“…In addition, in Ref. [28] the ratio of the measured cross section to DIS prediction is 1.3±0.45. The central value would be about 0.1 smaller if the contribution from W -boson production were included.…”

“…In present IceCube measurements of the cross section, the uncertainty is 35% when only the cross section normalization is checked (one wide energy bin for all data, plus assuming the shape of the standard model cross section) [28] or a factor of 4 when these assumptions are relaxed (several energy bins, no prior on the cross section shape) [29]. The energy ranges of both are comparable to where W -boson production is important.…”

“…The IceCube detections are also a breakthrough in neutrino physics. By comparing the observed spectra of events that have traveled through Earth or not, the cross section can be measured at energies far above the reach of laboratory experiments [24][25][26][27][28][29]. And many models of new physics have been powerfully limited by the IceCube data [30][31][32][33][34][35][36][37][38][39][40][41][42][43].…”

“…They are also an inseparable part of the measured neutrino cross section. Though the uncertainty of measured cross sections by IceCube is larger than the change in the cross section due to W -boson production [28,29], the measured uncertainties will decrease. In addition, in Ref.…”

Far-forward neutrinos at the Large Hadron Collider

“…Measurements of LHC forward tau neutrino interactions can be used for direct tests of lepton flavor universality in charged current interactions with much higher statistics than achieved by Donut [19,20] and Opera [21,22]. Measurements of the interaction cross-sections of muon neutrinos from heavy-flavor decays at the LHC with the nucleons/nuclei of the target will help to close the gap between direct neutrino cross-section measurements for E ν < 370 GeV [1] and the IceCube Collaboration's determination of the averaged cross-section for neutrino plus antineutrino deep-inelastic scattering with nucleons for E ν = 6.3−980 TeV [23]. LHC forward neutrinos will provide the first opportunity for direct neutrino and antineutrino cross-section measurements for neutrino energies up to E ν 2 TeV.…”