Constraining The Neutrino-Nucleon Cross Section with the Ultrahigh-Energy KM3NeT Event

TL;DR

This paper uses a high-energy neutrino event detected by KM3NeT to set an upper limit on the neutrino-nucleon cross section at energies beyond current accelerators, constraining new physics scenarios.

Contribution

It provides the first upper limit on the neutrino-nucleon cross section at ultra-high energies using a single event from KM3NeT, informing beyond Standard Model physics.

Findings

Upper limit on cross section: < 40 times the Standard Model prediction at 20 TeV CM energy.

Demonstrates potential of neutrino telescopes to probe new physics beyond accelerators.

Future telescopes could significantly improve constraints on neutrino interactions.

Abstract

KM3NeT's detection of a muon track produced by a $\sim 220 \, {\rm PeV}$ neutrino provides an opportunity to probe physics at center-of-momentum energies greater than those probed by the Large Hadron Collider or other existing particle accelerators. In this study, we use this single event to place an upper limit on the neutrino-nucleon cross section of $\sigma_{\nu N} < 40 \, \sigma_{\nu N}^{\rm SM}$ at $E_{\rm CM} \sim 20 \, {\rm TeV}$. This result can be used to constrain a variety of scenarios beyond the Standard Model. With future very large volume neutrino telescopes, constraints on the neutrino-nucleon scattering cross section are expected to become substantially more stringent and, in some scenarios, could become competitive with accelerator probes of new physics.