Neutrino Electromagnetic Properties and the Weak Mixing Angle at the LHC Forward Physics Facility

TL;DR

The paper explores how the proposed Forward Physics Facility at the LHC can significantly improve measurements of neutrino electromagnetic properties and the weak mixing angle, enhancing constraints beyond previous experiments.

Contribution

It demonstrates the potential of the FPF to set new bounds on neutrino magnetic moments, millicharge, charge radius, and measure the weak mixing angle with high precision.

Findings

Enhanced sensitivity to tau neutrino magnetic moment and millicharge.

Strongest bounds on electron neutrino charge radius.

Potential to measure the weak mixing angle with 3% precision.

Abstract

The LHC produces an intense beam of highly energetic neutrinos of all three flavors in the forward direction, and the Forward Physics Facility (FPF) has been proposed to house a suite of experiments taking advantage of this opportunity. In this study, we investigate the FPF's potential to probe the neutrino electromagnetic properties, including neutrino millicharge, magnetic moment, and charge radius. We find that, due to the large flux of tau neutrinos at the LHC, the FPF detectors will be able to provide more sensitive constraints on the tau neutrino magnetic moment and millicharge than previous measurements at DONUT, by searching for excess in low recoil energy electron scattering events. We also find that, by precisely measuring the rate of neutral current deep inelastic scattering events, the FPF detectors have the potential to obtain the strongest experimental bounds on the neutrino charge radius for the electron neutrino, and one of the leading bounds for the muon neutrino flavor. The same signature could also be used to measure the weak mixing angle, and we estimate that $\sin^2 \theta_W$ could be measured to about $3\%$ precision at a scale $Q \sim 10$ GeV, shedding new light on the longstanding NuTeV anomaly.