Speaker
Description
Ultra-high-energy (UHE) cosmic neutrinos, with energies above 100 PeV, could be finally discovered in the near future. Measuring their flavor composition would reveal information about their production and propagation, but new techniques are needed for UHE neutrino telescopes to have the capabilities to do it.
In this talk I will introduce a new way to measure the UHE neutrino flavor composition. Without relying on individual telescopes to have flavor-identification capabilities, this method yields flavor sensitivity from the combined data of two detectors: one sensitive to all flavors$-$the radio array of IceCube-Gen2$-$and one mostly sensitive to $\nu_\tau$$-$GRAND.
I will present the first measurement forecasts of the UHE $\nu_\tau$ content available in the literature. Then, I will show the projected results that can be extracted from this observable. For astrophysics, it constrains the production mechanism of UHE neutrinos; for fundamental physics, it vastly improves the constraints on Lorentz-invariance violation.
