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ATLAS b-jet triggers in Run 3
No full textA number of flagship analyses in the ATLAS experiment rely on real-time b-tagging to efficiently record data. In run 3, the jet and b-jet trigger was updated with state of the art machine learning, to reduce background rates and improve efficiency, while remaining within the constraints of the trigger hardware. We will discuss the design, optimization, deployment, and validation of the ATLAS run 3 b-jet triggers, and their impact several important physics analyses
Classifying hadronic objects in ATLAS with ML/AI algorithms
No full textHadronic object reconstruction & classification is one of the most promising settings for cutting-edge machine learning and artificial intelligence algorithms at the LHC. In this contribution, highlights of ML/AI applications by ATLAS to QCD and boosted-object identification, MET reconstruction and other tasks will be presented
Combination of exclusion limits on modified couplings between top quarks and heavy bosons in the effective field theory framework
No full textThe statistical combination of two indirect searches for physics beyond the standard model within the framework of effective field theory using of data collected by the CMS experiment at is presented. In the first measurement, top quarks in association with a hadronically decaying boson with large transverse momentum are studied, while in the second, the production of top quarks associated with additional leptons is explored. The events examined in the first search involve a single lepton (electron or muon) in the final state while in the latter case, events with two same-charge leptons, three leptons, or four or more leptons are studied. Eight Wilson coefficients are simultaneously measured, each of which is associated to an independent operator in effective field theory. The combination of the two analyses improves the results by up to with respect to either analysis alone
CERN Tape Archive Workshop : CTA 2025
No full textDuring Run-3, CTA has demonstrated very high write efficiency at nominal DAQ rates. For retrieval, CTA relies on time-based colocation of data on tape, but this has proved to be much less efficient than expected. Furthermore, the ratio of tape reads to writes is expected to significantly increase during Run-4, as some LHC experiments move towards the “tape carousel” model. Two years ago, we started to analyse the constraints from the experiments and tape sites, in order to devise a way to improve retrieve efficiency. The resulting Archive Metadata proposal is a practical abstraction layer between experiment data management and tape storage endpoints. It allows to express how group of files are likely be staged together.
This talk will present how this project has evolved over the past two years, its initial proposal implementation and finally an overview of the collected metadata during the 2024 Heavy Ion run.
Finally, we will also give an overview of the plan for upcoming research and development using Archive Metadata
NNLOJET: a parton-level event generator for jet cross sections at NNLO QCD accuracy
No full textThe antenna subtraction method for NNLO QCD calculations is implemented in the NNLOJET parton-level event generator code to compute jet cross sections and related observables in electron-positron, lepton-hadron and hadron-hadron collisions. We describe the open-source NNLOJET code and its usage
Overview of EFT-based searches involving top quarks at ATLAS
No full textMany-parameter fits to precise measurements in the framework of the Standard Model Effective Field Theory are becoming a standard interpretation of LHC and other collider data. In this contribution an overview is given of state-of-the-art EFT interpretations in ATLAS with particular emphasis on results in the top quark sector
Neutrino Theory in the Precision Era
No full textThis document summarises discussions on future directions in theoretical neutrino physics, which are the outcome of a neutrino theory workshop held at CERN in February 2025. The starting point is the realisation that neutrino physics offers unique opportunities to address some of the most fundamental questions in physics. This motivates a vigorous experimental programme which the theory community fully supports. \textbf{A strong effort in theoretical neutrino physics is paramount to optimally take advantage of upcoming neutrino experiments and to explore the synergies with other areas of particle, astroparticle, and nuclear physics, as well as cosmology.} Progress on the theory side has the potential to significantly boost the physics reach of experiments, as well as go well beyond their original scope. Strong collaboration between theory and experiment is essential in the precision era. To foster such collaboration, \textbf{we propose to establish a CERN Neutrino Physics Centre.} Taking inspiration from the highly successful LHC Physics Center at Fermilab, the CERN Neutrino Physics Centre would be the European hub of the neutrino community, covering experimental and theoretical activities
Precision cross-sections for advancing cosmic-ray physics and other applications: a comprehensive programme for the next decade
No full textCosmic-ray physics in the GeV-to-TeV energy range has entered a precision era thanks to recent data from space-based experiments. However, the poor knowledge of nuclear reactions, in particular for the production of antimatter and secondary nuclei, limits the information that can be extracted from these data, such as source properties, transport in the Galaxy and indirect searches for particle dark matter. The Cross-Section for Cosmic Rays at CERN workshop series has addressed the challenges encountered in the interpretation of high-precision cosmic-ray data, with the goal of strengthening emergent synergies and taking advantage of the complementarity and know-how in different communities, from theoretical and experimental astroparticle physics to high-energy and nuclear physics. In this paper, we present the outcomes of the third edition of the workshop that took place in 2024. We present the current state of cosmic-ray experiments and their perspectives, and provide a detailed road map to close the most urgent gaps in cross-section data, in order to efficiently progress on many open physics cases, which are motivated in the paper. Finally, with the aim of being as exhaustive as possible, this report touches several other fields -- such as cosmogenic studies, space radiation protection and hadrontherapy -- where overlapping and specific new cross-section measurements, as well as nuclear code improvement and benchmarking efforts, are also needed. We also briefly highlight further synergies between astroparticle and high-energy physics on the question of cross-sections