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The new hardware trigger processor at NA62 experiment: Status of the System and First Results
No full textThe NA62 experiment is designed to study rare and ultra-rare kaon decays using a decay-in-flight technique. The Trigger and Data Acquisition (TDAQ) system of NA62 is multi-level, making it critically dependent on the performance of the inter-level network. To manage the huge amount of data produced by the detectors, three levels of triggers are employed. The first level L0TP, implemented using an FPGA device, has been in operation since the start of data taking in 2016. In order to increase the efficiency of the system and implement additional algorithms, an upgraded system (L0TP+) was developed starting in 2018. This upgrade avails itself of a high-end FPGA available on the market, offering more computing power, larger local memory and higher transmission bandwidth. We have planned tests for a new trigger algorithm that implements quadrant-based logic for the veto systems. This new approach is expected to improve the main trigger efficiency by several percent. Extensive tests were conducted using a parasitic setup that included a set of Network TAPs and a commodity server, allowing for proficient comparison of trigger decisions on an event-by-event basis. The experience gained from this parasitic mode operation can be leveraged for the next data-taking period as a development setup to implement additional features, thereby accelerating the TDAQ upgrade. After the testing period, the new system has been adopted as the online processor since 2023. Preliminary results on the efficiency of the new system will be reported. Integration with the new AI-based FPGA-RICH system, which performs online partial particle identification, will also be discussed
CppInterOp: Advancing Interactive C++ for High Energy Physics
No full textThe Cling C++ interpreter has transformed language bindings by enabling incremental compilation at runtime. This allows Python to interact with C++ on demand and lazily construct bindings between the two. The emergence of Clang-Repl, within the LLVM compiler framework, as a potential alternative to Cling highlights the need for a unified framework for interactive C++ technologies.We present CppInterOp, a C++ interoperability library that leverages Cling and LLVM’s Clang-Repl to provide a minimalist and backward-compatible API facilitating seamless language interoperability. This provides downstream interactive C++ tools with the compiler as a service by embedding Clang and LLVM as libraries in their codebases. By enabling dynamic Python interactions with static C++ codebases, CppInterOp enhances computational efficiency and rapid development in high-energy physics. The library offers reflection and ondemand JIT compilation APIs enabling cppyy, an automatic, run-time, Python- C++ bindings generator. We also demonstrate CppInterOp’s utility in diverse computing environments through its adoption as the runtime engine for xeuscpp, a Jupyter kernel designed for C++.CppInterOp is a general-purpose library inspired by the developments in the ROOT framework, which pushed the frontiers of interactive C++. It aims to extend this approach and serve as an integral component of ROOT, enhancing performance and resilience. This article introduces CppInterOp to the HEP community and showcases how it optimizes cross-language execution and computational tasks in high-energy physics, making it a valuable tool for researchers and developers
Search for new physics in triple boson production at 13 TeV using the effective field theory approach
No full textA search for new physics in the production of three massive gauge bosons (VVV, where V is W or Z) is presented. The event selection emphasizes the ``boosted'' regime in which all three bosons have a transverse momentum above 200 GeV. Standard model processes contribute few events in the boosted regime. When a boosted W or Z boson decays hadronically, the decay products tend to form a large-radius jet with substructure called a V-tagged jet. Special techniques to reconstruct and select V-tagged jets are applied. Events are categorized according to the number and kinematic features of charged leptons and V-tagged jets. Event yields are obtained in bins of a suitable kinematic variable such as the scalar sum of the transverse momenta of the reconstructed objects in the event. No excess over standard model expectations is observed, and bounds are placed on Wilson coefficients for a set of mass dimension-6 and -8 operators in the framework of standard model effective field theory.
The two most stringent bounds placed by this analysis are TeV and TeV
EDM4hep.jl: Analysing EDM4hep files with Julia
No full textEDM4hep aims to establish a standard event data model for the storage and exchange of event data in HEP experiments, thereby fostering collaboration across various experiments and analysis frameworks. The Julia package EDM4hep.jl is capable of generating Julia-friendly structures for the EDM4hep data model and reading event data files in ROOT format (either TTree or RNTuple) that are written by C++ programs, utilising the UnROOT.jl package. This paper explores the motivations behind the primary design choices of this package, such as the exclusive use of structure of arrays (SoA) to access the stored collections, which then empowers users to develop ergonomic data analyses using Julia’s high-level concepts and functionality, while maintaining performance comparable to C++ programs. Several examples are given to illustrate how efficient data analysis can be achieved using high-level objects, eliminating the need to resort to flat n-tuples
Thoroughly testing and integrating hundreds of Pull Requests per month: ROOT’s new Cost-efficient and Feature Rich GitHub-based CI
No full textROOT is an open source framework, freely available on GitHub, at the heart of data acquisition, processing and analysis of HE(N)P experiments, and beyond. It is developed collaboratively: contributions are not authored only by ROOT team members, but also by the user community at large: developers and scientists from universities, labs as well as the private sector. More than 1500 GitHub Pull Requests are merged on average per year. It is in this context that code integration acquires a primary role. The review of code contributions isn’t enough: not only they need to be thoroughly reviewed, they also need to be thoroughly tested through a powerful CI infrastructure on several different platforms to comply with the high code quality standards of the project. Since the end of 2023, ROOT moved its continuous integration system from Jenkins to GitHub Actions. In this contribution, we characterise the transition to the GitHub CI, focussing on our strategy, its implementation and the lessons learned, as well as the advantages the new system offers with respect to the previous one. Particular emphasis will be given to the evaluation of the cost-benefit ratio for Jenkins and GitHub Actions for the ROOT project. We also describe how we manage to run in less than one hour thousands of unit, integration, functional and end-to-end tests on different flavours of Windows, four versions of macOS, as well as about ten of the most used Linux distributions, taking advantage of the CERN computing infrastructure
Observation of tWZ production at the CMS experiment
No full textThe first observation of single top quark production in association with a W and a Z boson in proton-proton collisions is reported. The analysis uses data at center-of-mass energies of 13 and 13.6 TeV recorded with the CMS detector at the CERN LHC, corresponding to a total integrated luminosity of 200 fb. Events with three or four charged leptons, which can be electrons or muons, are selected. Advanced machine-learning algorithms and improved reconstruction methods, compared to an earlier analysis, result in an unprecedented sensitivity to tWZ production. The measured cross sections for tWZ production are 248 52 fb and 244 74 fb for 13 and 13.6 TeV, respectively. The signal is established with a statistical significance of 5.8 standard deviations, with 3.5 expected, compared to the background-only hypothesis.The first observation of single top quark production in association with a W and a Z boson in proton-proton collisions is reported. The analysis uses data at center-of-mass energies of 13 and 13.6 TeV recorded with the CMS detector at the CERN LHC, corresponding to a total integrated luminosity of 200 fb. Events with three or four charged leptons, which can be electrons or muons, are selected. Advanced machine-learning algorithms and improved reconstruction methods, compared to an earlier analysis, result in an unprecedented sensitivity to tWZ production. The measured cross sections for tWZ production are 248 52 fb and 244 74 fb for =13 and 13.6 TeV, respectively. The signal is established with a statistical significance of 5.8 standard deviations, with 3.5 expected, compared to the background-only hypothesis
Direct vs. indirect search probes
No full textThe discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable to solely explain some observations. Many extensions of the Standard Model addressing such shortcomings introduce additional Higgs bosons, beyond-the-Standard-Model (BSM) couplings to the Higgs boson, or new particles decaying into Higgs bosons. Next to direct searches, the event rates and kinematics of Higgs boson production and decay processes at the LHC are sensitive probes of possible new phenomena. This talk presents the most recent results for direct searches in the extended Higgs sector, as well as the measurements of Higgs boson production and decay rates, obtained using the full Run 2 and partial Run 3 pp collision dataset collected by the ATLAS experiment at 13 TeV and 13.6 TeV. These include total and fiducial cross-sections for the main Higgs boson processes as well as branching ratios into final states with bosons and fermions
LUCID, the ATLAS luminosity detector in LHC Run-3 and its upgrade for HL-LHC
No full textThe LUCID-2 detector is the main luminometer of the ATLAS experiment and the only one able to provide a reliable luminosity determination in all beam configurations, luminosity ranges and at bunch-crossing level. During LHC Run-2 ATLAS has measured luminosity with a precision of 0.8\%, the most precise ever among all experiments running at a hadron collider. LUCID-2 is now providing ATLAS with the luminosity measurement also in LHC Run-3. Preliminary results on the acquired datasets will be presented. The ATLAS physics program at High Luminosity LHC (HL-LHC) calls for a precision in the luminosity measurement of 1\%. To fulfill such requirement in an environment characterized by up to 140 simultaneous interactions per crossing (200 in the ultimate scenario), ATLAS will feature several luminosity detectors. LUCID-3, the upgrade of LUCID-2, is one of these. In this contribution, two options for LUCID-3 under study are presented: the first is based on photomultipliers (PMT), as for LUCID-2, located farther from the beam-pipe to reduce the acceptance and avoid the detector saturation; the second is based on optical fibers acting as Cherenkov radiators and read-out by PMTs located in a low radiation area. All PMTs will be monitored by a radioactive Bi source to ensure long-term stability to better than 1\%. The status of the analysis of the data acquired in Run-3 with prototypes of both technologies installed in ATLAS will be presented focusing on the possible final LUCID-3 design