Periodic Reporting for period 2 - UNOS (Unifying Neutrino Observatories Searches)
Período documentado: 2022-11-01 hasta 2023-10-31
The existence of additional neutrinos mass eigenstates is one of the open questions in Particle Physics. Several experiments have measured anomalous neutrino oscillations that the presence of a fourth neutrino could explain. The preferred mass splitting from these anomalies is in the region between 1 to 10 eV2.
The project Unifying Neutrino Observatories Searches aims to probe sterile neutrinos in the 0.1-10 eV2 mass splitting regime. The primary analysis uses atmospheric neutrinos with TeV energies detected with neutrino telescopes.
UNOS set out several scientific objectives: (a) to enhance simulation tools, focusing on implementing new neutrino cross-section models in the TeV energy range; (b) to investigate new observables and data samples to enhance sensitivity to sterile neutrinos with neutrino telescopes; and (c) to update sterile neutrino searches through a newly developed analysis framework.
The project delivered several outcomes. First, it introduced new models for simulating neutrino interactions across energies from GeV to EeV. Second, it upgraded a fitting framework to enable atmospheric neutrino experiments to test scenarios beyond the standard model in a standardized manner. Third, it introduced a new search for sterile neutrinos using neutrino telescopes.
The project has achieved world-leading constraints on sterile neutrinos by leveraging data from the IceCube collaboration. The findings of this analysis are highly significant for the field, sparking discussions among phenomenologists and theorists about its implications for the sterile neutrino landscape. Additionally, for the first time, the project has calculated the sensitivity of the KM3NeT-ARCA detector to sterile neutrinos using high-energy atmospheric neutrinos.
The project Unifying Neutrino Observatories Searches aims to probe sterile neutrinos in the 0.1-10 eV2 mass splitting regime. The primary analysis uses atmospheric neutrinos with TeV energies detected with neutrino telescopes.
UNOS set out several scientific objectives: (a) to enhance simulation tools, focusing on implementing new neutrino cross-section models in the TeV energy range; (b) to investigate new observables and data samples to enhance sensitivity to sterile neutrinos with neutrino telescopes; and (c) to update sterile neutrino searches through a newly developed analysis framework.
The project delivered several outcomes. First, it introduced new models for simulating neutrino interactions across energies from GeV to EeV. Second, it upgraded a fitting framework to enable atmospheric neutrino experiments to test scenarios beyond the standard model in a standardized manner. Third, it introduced a new search for sterile neutrinos using neutrino telescopes.
The project has achieved world-leading constraints on sterile neutrinos by leveraging data from the IceCube collaboration. The findings of this analysis are highly significant for the field, sparking discussions among phenomenologists and theorists about its implications for the sterile neutrino landscape. Additionally, for the first time, the project has calculated the sensitivity of the KM3NeT-ARCA detector to sterile neutrinos using high-energy atmospheric neutrinos.
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.
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.
UNOS enhanced our knowledge in several frontiers of neutrino physics. First, we tested the predictions of neutrino production in the atmosphere. In addition, we fostered the development of new tools to simulate neutrino interactions. A better understating of these processes boosted the studies of other Beyond Standard Model scenarios like dark matter searches or quantum decoherence.
This project constituted an excellent example of coordination between two international collaborations, IceCube and KM3NeT. It established a common ground for future joint analyses between different neutrino telescopes in Particle Physics. A clear example is the exchange of software tools developed as open-source code, like GENIE, nuSQUIDs, and GolemFit. Moreover, this project improved the network between Harvard and IFIC, enabling scientists to communicate and exchange ideas more efficiently.
Finally, carrying out the first phase of this project in the US had significant societal implications. We have encouraged high school students from Spanish-speaking communities in the Boston area to become interested in cutting-edge research in particle physics, providing a unique opportunity for them to develop their scientific skills. This project thus serves as a bridge between different communities in the US and Europe, fostering technical and cultural exchange.
This project constituted an excellent example of coordination between two international collaborations, IceCube and KM3NeT. It established a common ground for future joint analyses between different neutrino telescopes in Particle Physics. A clear example is the exchange of software tools developed as open-source code, like GENIE, nuSQUIDs, and GolemFit. Moreover, this project improved the network between Harvard and IFIC, enabling scientists to communicate and exchange ideas more efficiently.
Finally, carrying out the first phase of this project in the US had significant societal implications. We have encouraged high school students from Spanish-speaking communities in the Boston area to become interested in cutting-edge research in particle physics, providing a unique opportunity for them to develop their scientific skills. This project thus serves as a bridge between different communities in the US and Europe, fostering technical and cultural exchange.