Speaker
Description
The structure of the extragalactic diffuse neutrino flux below 30 TeV energies remains an open question. The Enhanced Starting Track Event Selection (ESTES) has prefers a single power law (SPL), while two other combined track and contained cascade event selections, the Combined Fit and the Medium Energy Starting Event Selection (MESE), prefer a >4σ preference for a broken power law (BPL) over SPL below ~30 TeV. Including more cascade events, noted for their energy resolution and background discrimination at lower energies, could contribute to clarifying the spectrum. We present a new analysis of the diffuse neutrino flux using a neural network-based event selection of both contained and uncontained cascade events from IceCube, where uncontained cascades are neutrinos with interaction vertices at the edge or outside of the detector instrumentation volume. The inclusion of partially contained cascades down to 10 TeV increases the effective area and enhances sensitivity to characterizing the diffuse neutrino flux. The selection incorporates systematic improvements of the Antarctic ice and atmosphere, along with updated modeling of the atmospheric neutrino background, aiming to resolve features of the astrophysical neutrino spectrum down to energies of 1 TeV. We report progress towards characterizing the extragalactic diffuse neutrino flux using this new event selection and discuss implications for interpreting the diffuse neutrino spectrum in the cascade channel at ~TeV energies.
