During this action, three main work packages were developed: (a) update simulations of neutrino interactions; (b) maximize observing power of TeV atmospheric neutrinos with IceCube; (c) provide software training; (d) Conduct IceCube and KM3NeT analyses.
a) The researcher developed a new code, HEDIS, to simulate high-energy neutrino interactions. Integrated into GENIE, a widely used open-source neutrino generator, HEDIS was validated and incorporated into the simulation chains of KM3NeT and IceCube. Collaborating with the Harvard team, a novel mechanism for generating high-energy tau neutrinos through neutrino propagation in Earth was discovered. This groundbreaking work was published in Physical Review Letters (2022) and highlighted in multiple press releases. Additionally, in collaboration with NIKHEF colleagues, a new method was devised to describe structure functions in the low-energy transfer regime, crucial for computing Deep Inelastic Scattering cross-sections from 10 GeV to 10 EeV. This achievement was published in JHEP (2023) and presented at the ICRC conference in Nagoya (2023). Furthermore, in conjunction with a researcher from LBNL, the team explored approaches to constrain neutrino flux at CERN's FPF using the low-nu method, resulting in a publication in Physical Review D (2024).
b) Collaborating with researchers from Harvard, MIT, and UTA, the researcher identified key observables for sterile neutrino constraints using neutrino telescopes. They developed a tool employing Boosted Decision Trees to reject atmospheric muons, significantly enhancing background rejection and selection efficiency compared to previous methods. Neural Networks were used to classify neutrino interactions as through-going or starting events, while a new energy reconstruction method improved energy resolution for TeV-range neutrinos. Similar methods were applied to simulations from the KM3NeT-ARCA detector, focusing on selecting pure samples of muon-neutrino charged current interactions. Initial findings were presented internally to IceCube and KM3NeT members and shown at the NuFact conference (Utah, 2022).
c) A dedicated work package focused on advancing the researcher's software skills. The primary outcome, GolemFit, a new framework, is designed to test scenarios beyond the standard model using atmospheric neutrinos. Collaborating with Harvard University, a technical publication detailing the framework's capabilities is currently being developed.
d) The core objective involved developing analyses to search for sterile neutrinos using IceCube and KM3NeT detectors. The second phase focused on conducting and refining these analyses. Using 10.7 years of IceCube data, the researcher performed a search for eV-scale sterile neutrinos. Results underwent internal review within the IceCube collaboration and have been submitted to Physical Review Letters and Physical Review D. Initial outcomes were presented for the first time at the TeVPA conference (Naples, 2023). Employing a similar analysis strategy, the researcher conducted the first sensitivity study of the KM3NeT-ARCA detector for these particles, with preliminary results shared during internal KM3NeT collaboration meetings.
Additionally, the project included several outreach activities aimed at fostering interest in particle physics within the Spanish-speaking youth community. Events were organized, including introductory courses for primary and high-school students, and instructional YouTube videos were created, providing insights into building homemade particle detectors.
