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Study on discharge and short circuit generation in CMS GE1/1 triple-GEM detectors during Run 3
No full textThe installation of the new GE1/1 station of Gas ElectronMultiplier (GEM) detectors in the Compact Muon Solenoid (CMS)experiment was completed during the Long Shutdown 2 (LS2) phase ofthe Large Hadron Collider (LHC). The GE1/1 station has beenoperational in the CMS detector since the beginning of the Run-3data-taking phase, and for the first time the GEM technology wasdeployed on a large scale, comprised of 144 chambers and tested inrunning conditions as integral part of the CMS data acquisition,reconstruction, and analysis chain. The deployment of the GEMdetector required careful planning throughout the years, posingseveral challenges of practical and conceptual nature in integratingan entirely new subsystem in the existing CMS frame. Operations onthe other hand provided a unique opportunity to test the GEMtechnology in never-before seen conditions, and an occasion to studytheir behavior during data taking.In describing some of the solutions to the posed challenges and thefindings during the data-taking, the article will focus on theaspects related to power system management, including high-voltageand current monitoring, which is intrinsically related to theresponse of the chamber due to the workings of the GEM foil chargeflow. To this end, this article will illustrate the operations ofGE1/1 detectors in the first two years of Run-3, with a particularfocus on the analysis of discharge occurrences, on the generation ofshort circuits in GE1/1 GEM foils and on the adopted mitigationstrategies. The applied layout of the GEM detectors is thoroughlydescribed, and detailed operating conditions of the detectors arediscussed, along with the actions taken to mitigate these events
chATLAS: An AI Assistant for the ATLAS Collaboration
No full textThe ATLAS Collaboration is composed of around 6,000 scientists, engineers, developers, students and administrators, with decades of institutional documentation spread across wikis, code docs, meeting agendas, recommendations, publications, tutorials, and project management systems. With the advent of retrieval augmented generation (RAG) and sophisticated large language models (LLMs) such as GPT-4, there is now an opportunity to produce a “front door” to this intimidatingly large corpus. ChATLAS is an attempt to provide this entrypoint, as ATLAS’ official AI assistant and search system. In this contribution, we review the past year of developments, present the latest updates to the system, and introduce ongoing work to improve back-end performance, agentic information gathering, and science-centric design components
Flavour Physics at the Energy Frontier
No full textThis talk would cover flavor physics measurements that require the high energy of the LHC, i.e., flavor properties of top decays such as CKM couplings, searches for lepton flavor violation, etc; and flavor properties of Higgs decays such as Yukawa couplings, CP violation in couplings, etc. The talk is expected to cover the field, including relevant results from CMS (and any other experiment). The talk is not expected to cover B, D, or tau lepton decays, as those topics will be covered in other plenary talks. The talk is scheduled for 25 minutes, with an additional 5 minutes for questions
Tensor Network for Anomaly Detection in the Latent Space of Proton Collision Events at the LHC
No full textThe pursuit of discovering new phenomena at the Large Hadron Collider (LHC) requires constant innovation in algorithms and technologies. Tensor networks are mathematical models at the intersection of classical and quantum machine learning, which present a promising and efficient alternative for tackling these challenges. In this study, we propose a tensor network-based strategy for anomaly detection at the LHC and demonstrate its superior performance in identifying new phenomena compared to established quantum methods. Our model is a parameterized matrix product state with an isometric feature map, processing a latent representation of simulated LHC data generated by an autoencoder. Our results highlight the potential of tensor networks to enhance new-physics discovery.The pursuit of discovering new phenomena at the Large Hadron Collider (LHC) demands constant innovation in algorithms and technologies. Tensor networks are mathematical models on the intersection of classical and quantum machine learning, which present a promising and efficient alternative for tackling these challenges. In this work, we propose a tensor network-based strategy for anomaly detection at the LHC and demonstrate its superior performance in identifying new phenomena compared to established quantum methods. Our model is a parametrized Matrix Product State with an isometric feature map, processing a latent representation of simulated LHC data generated by an autoencoder. Our results highlight the potential of tensor networks to enhance new-physics discovery
Numerical stability of force-gradient integrators and their Hessian-free variants in lattice QCD simulations
No full textWe investigate the numerical stability of force-gradient integrators and their Hessian-free variants within the molecular dynamics step of the Hamiltonian Monte Carlo algorithm in lattice QCD simulations. A linear stability analysis of (Hessian-free) force-gradient integrators is conducted by investigating the harmonic oscillator as a test equation. By performing detailed stability investigations for the entire family of self-adjoint integrators with up to eleven exponentials per time step, we detect promising integrator variants that are providing a good trade-off between accuracy and numerical stability. Simulations for the two-dimensional Schwinger model demonstrate that there are no significant differences in the stability domain of a force-gradient integrator and its Hessian-free counterpart. Furthermore, lattice QCD simulations are conducted to emphasize the significance of numerical stability as a metric for evaluating the computational efficiency of integrators when applied to lattice QCD simulations
Coherent photoproduction of and excited vector mesons in ultraperipheral PbPb collisions
No full textThe invariant-mass distribution for the coherent photoproduction of dipions in ultraperipheral PbPb collisions is measured using data, corresponding to an integrated luminosity of b, collected by the LHCb experiment in 2018 at a nucleon-nucleon centre-of-mass energy TeV. The dominant contribution is due to the meson but a consistent description across the full invariant-mass range requires accounting for the meson and introducing two resonances at masses of MeV and MeV with widths of about 300 MeV. The cross-section for each meson is measured differentially in twelve bins of rapidity from 2.05 to 4.90. Significant nuclear suppression is observed for the meson compared to expectations based on photoproduction on the proton
Higgs CP properties and EFT measurements from ATLAS+CMS
No full textThis talk presents precise measurement of the CP properties of the Higgs boson using the full dataset collected in pp collisions at 13 TeV during Run 2 and at 13.6 TeV during Run 3 of the LHC. The measurements are performed in various Higgs boson production and decay modes, as well as their combinations. Observation of deviations between these measurements and Standard Model (SM) predictions would be a sign of possible new phenomena beyond the SM
Space Charge in Circular Machines
No full textSpace charge forces, which arise directly from the beam's charge distribution and include the influence of image charges and currents induced by interactions with a perfectly conducting, smooth pipe, are very important in high-intensity, low-energy accelerators. These forces play a key role under various beam dynamics regimes, leading to effects such as energy spread, modifications of betatron tunes, and potential instabilities. This lecture will explore the fundamental characteristics of space charge effects in circular accelerators