Periodic Reporting for period 4 - LightAtLHC (Search for Axion-Like Particles at the LHC)
Période du rapport: 2024-09-01 au 2025-02-28
The Light@LHC project addresses a fundamental question in physics: the existence of axion-like particles (ALPs) and their potential role in explaining phenomena beyond the Standard Model (BSM). Despite the Standard Model's success in describing known particles and interactions, it falls short in explaining dark matter, the strong CP problem, and certain cosmological observations. ALPs, as hypothetical particles, offer compelling solutions to these mysteries. However, specific parameter regimes—especially involving long-lived ALPs—had remained unexplored, limiting our understanding of these particles and their implications.
This research is not only critical to advancing fundamental physics but also holds broader societal significance. Discovering ALPs or ruling out viable BSM models can reshape our understanding of the universe's fundamental laws. Such breakthroughs influence technological innovation, as progress in particle physics has historically led to advancements in medical imaging, data processing, and sensor technologies. Additionally, probing the nature of dark matter and potential new forces in the universe enriches our scientific and philosophical perspectives on the cosmos.
The overall objectives of the Light@LHC project were to develop new search strategies for ALPs at the Large Hadron Collider (LHC) and contribute to the broader scientific community through innovation and collaboration. Key milestones included creating advanced reconstruction and trigger algorithms for displaced photon signatures, developing the FASER Preshower detector, and conducting detailed analyses of heavy-ion collisions and Higgs boson decays. These efforts resulted in the world's most precise limits on certain ALP interactions and introduced new methods for exploring long-lived particles. The project also involved initiating new research directions, including tabletop experiments at the University of Bonn and Mainz to search for anoxic dark matter.
Overall, the Light@LHC project not only advanced the frontiers of particle physics but also nurtured the careers of young scientists, contributed to global scientific knowledge, and demonstrated the impactful role of ERC funding in enabling high-risk, high-reward research.
This research is not only critical to advancing fundamental physics but also holds broader societal significance. Discovering ALPs or ruling out viable BSM models can reshape our understanding of the universe's fundamental laws. Such breakthroughs influence technological innovation, as progress in particle physics has historically led to advancements in medical imaging, data processing, and sensor technologies. Additionally, probing the nature of dark matter and potential new forces in the universe enriches our scientific and philosophical perspectives on the cosmos.
The overall objectives of the Light@LHC project were to develop new search strategies for ALPs at the Large Hadron Collider (LHC) and contribute to the broader scientific community through innovation and collaboration. Key milestones included creating advanced reconstruction and trigger algorithms for displaced photon signatures, developing the FASER Preshower detector, and conducting detailed analyses of heavy-ion collisions and Higgs boson decays. These efforts resulted in the world's most precise limits on certain ALP interactions and introduced new methods for exploring long-lived particles. The project also involved initiating new research directions, including tabletop experiments at the University of Bonn and Mainz to search for anoxic dark matter.
Overall, the Light@LHC project not only advanced the frontiers of particle physics but also nurtured the careers of young scientists, contributed to global scientific knowledge, and demonstrated the impactful role of ERC funding in enabling high-risk, high-reward research.
During the Light@LHC project, the primary goal was to search for axion-like particles (ALPs) within a mass range of 10 MeV to 1 TeV, particularly focusing on extremely low axion-photon couplings. The research aimed to probe parameter spaces relevant to models addressing the discrepancy between theoretical and experimental values of the muonic (g-2). Over the course of the project, three distinct phases were completed, each contributing significantly to the scientific objectives.
In Phase 1, the team developed advanced trigger and photon reconstruction algorithms using modern machine learning techniques. These innovations enabled, for the first time, the identification of merged photon signatures and established a method to handle photons reconstructed with significant displacement from the original collision point in the detector. Additionally, the Light@LHC team in Mainz played a crucial role in constructing the FASER experiment, including designing and building a novel pre-shower detector scheme. The attached image shows members of the ERC Light@LHC Team during the installation of the FASER experiment during the Covid-19 pandemic.
Phase 2 focused on searching for ALPs at the ATLAS experiment through ultraperipheral proton-proton and lead-lead collisions. The results from this phase, published in peer-reviewed journals, set the most stringent limits to date, excluding the relevant parameter space between 5 GeV and 1 TeV. A significant component of this phase involved analyzing anomalous Higgs boson decays, where decays into two ALPs led to final states with four photons. By leveraging the tools developed in Phase 1, the team achieved world-leading limits on ALP masses between 1 and 60 GeV and uniquely probed extended ALP lifetimes down to 10E-7 1/TeV. Complementing the ATLAS analyses, the team examined FASER data, establishing additional unprecedented constraints on ALP interactions. The cumulative results were widely disseminated through publications, presentations, and media coverage, maximizing the project's impact on the scientific community and beyond.The results are illustrated on the attached images from the ATLAS and FASER collaborations.
In summary, the Light@LHC project successfully achieved all objectives, providing the most precise limits on ALP interactions within the explored parameter space. While no direct evidence for ALPs was found, the project advanced the field by developing innovative technologies and methodologies that will support future particle physics experiments. Additionally, the project fostered scientific growth and career development for team members, highlighting the far-reaching benefits of ERC funding in enabling high-impact research.
In Phase 1, the team developed advanced trigger and photon reconstruction algorithms using modern machine learning techniques. These innovations enabled, for the first time, the identification of merged photon signatures and established a method to handle photons reconstructed with significant displacement from the original collision point in the detector. Additionally, the Light@LHC team in Mainz played a crucial role in constructing the FASER experiment, including designing and building a novel pre-shower detector scheme. The attached image shows members of the ERC Light@LHC Team during the installation of the FASER experiment during the Covid-19 pandemic.
Phase 2 focused on searching for ALPs at the ATLAS experiment through ultraperipheral proton-proton and lead-lead collisions. The results from this phase, published in peer-reviewed journals, set the most stringent limits to date, excluding the relevant parameter space between 5 GeV and 1 TeV. A significant component of this phase involved analyzing anomalous Higgs boson decays, where decays into two ALPs led to final states with four photons. By leveraging the tools developed in Phase 1, the team achieved world-leading limits on ALP masses between 1 and 60 GeV and uniquely probed extended ALP lifetimes down to 10E-7 1/TeV. Complementing the ATLAS analyses, the team examined FASER data, establishing additional unprecedented constraints on ALP interactions. The cumulative results were widely disseminated through publications, presentations, and media coverage, maximizing the project's impact on the scientific community and beyond.The results are illustrated on the attached images from the ATLAS and FASER collaborations.
In summary, the Light@LHC project successfully achieved all objectives, providing the most precise limits on ALP interactions within the explored parameter space. While no direct evidence for ALPs was found, the project advanced the field by developing innovative technologies and methodologies that will support future particle physics experiments. Additionally, the project fostered scientific growth and career development for team members, highlighting the far-reaching benefits of ERC funding in enabling high-impact research.
The Light@LHC project made significant progress beyond the state of the art by setting the world's most precise limits on axion-like particles (ALPs) in the mass range of 10 MeV to 1 TeV, particularly for long-lived particles, and by pioneering innovative search strategies for anomalous Higgs boson decays and ultraperipheral heavy-ion collisions. The project developed advanced machine learning algorithms for photon reconstruction and trigger systems, enabling the identification of merged and displaced photon signatures for the first time. These neural network-based methods not only enhanced particle physics analyses but also demonstrated promising potential for broader applications, including pandemic modeling. This exciting interdisciplinary application is currently being explored in greater detail following the completion of the Light@LHC project.