Final state radiation from high and ultrahigh energy neutrino interactions

Understand

Charged leptons produced by high-energy and ultrahigh-energy neutrinos have a substantial probability of emitting prompt internal bremsstrahlung $\nu_\ell + N \rightarrow \ell + X + \gamma$.

• This can have important consequences for neutrino detection.
• We discuss observable consequences at high- and ultrahigh-energy neutrino telescopes and the Large Hadron Collider's Forward Physics Facility.
• Logarithmic enhancements can be substantial (e.g., $\sim 20\%$) when either the charged lepton's energy or the rest of the cascade is measured.