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Search for emerging jets in collisions at TeV with the ATLAS experiment
No full textA search for emerging jets is presented using 51.8 fb of proton-proton collision data at TeV, collected by the ATLAS experiment during 2022 and 2023. The search explores a hypothetical dark sector featuring 'dark quarks', which are charged under a confining gauge group and couple to the Standard Model via a new mediator particle. These dark quarks undergo showering and hadronization within the dark sector, forming long-lived dark mesons that decay back into Standard Model particles. This results in jets which contain multiple displaced vertices known as emerging jets. The analysis targets events with pairs of emerging jets, produced either through a vector mediator, , in the -channel, or a scalar mediator, , in the -channel. No significant excess over the Standard Model background is observed. Assuming a dark pion proper decay length between 5 and 50 mm, mediator masses between 600 and 2550 GeV are excluded for quark and dark quark coupling values of 0.01 and 0.1, respectively. For a quark-dark quark coupling of , mediator masses between 600 and 1375 GeV are excluded. These results provide the first direct constraints on emerging jet pair production via a mediator, and represent the first search to investigate emerging jet production via -channel exchange of a scalar mediator.A search for emerging jets is presented using 51.8 fb of proton–proton collision data at TeV, collected by the ATLAS experiment during 2022 and 2023. The search explores a hypothetical dark sector featuring ‘dark quarks’ that are charged under a confining gauge group and couple to the standard model (SM) via a new mediator particle. These dark quarks undergo showering and hadronisation within the dark sector, forming long-lived dark mesons that decay back into SM particles. This results in jets that contain multiple displaced vertices known as emerging jets. The analysis targets events with pairs of emerging jets, produced either through a vector mediator, Z′, in the s-channel, or a scalar mediator, Φ, in the t-channel. No significant excess over the SM background is observed. Assuming a dark pion proper decay length between 5 mm and 50 mm, Z′ mediator masses between 600 GeV and 2550 GeV are excluded for quark and dark quark coupling values of 0.01 and 0.1, respectively. For a quark dark-quark coupling of 0.1, Φ mediator masses between 600 GeV and 1375 GeV are excluded. These results represent the first direct search targeting emerging jet pair production via a Z′ mediator, as well as the first study of emerging jet production mediated by a scalar particle exchanged in the t-channel.A search for emerging jets is presented using 51.8 fb of proton-proton collision data at TeV, collected by the ATLAS experiment during 2022 and 2023. The search explores a hypothetical dark sector featuring 'dark quarks', which are charged under a confining gauge group and couple to the Standard Model via a new mediator particle. These dark quarks undergo showering and hadronization within the dark sector, forming long-lived dark mesons that decay back into Standard Model particles. This results in jets which contain multiple displaced vertices known as emerging jets. The analysis targets events with pairs of emerging jets, produced either through a vector mediator, , in the -channel, or a scalar mediator, , in the -channel. No significant excess over the Standard Model background is observed. Assuming a dark pion proper decay length between 5 and 50 mm, mediator masses between 600 and 2550 GeV are excluded for quark and dark quark coupling values of 0.01 and 0.1, respectively. For a quark-dark quark coupling of , mediator masses between 600 and 1375 GeV are excluded. These results provide the first direct constraints on emerging jet pair production via a mediator, and represent the first search to investigate emerging jet production via -channel exchange of a scalar mediator
Hybrid production status of the CMS Outer Tracker for the Phase-2 Upgrade
No full textThe CMS Collaboration will exchange the whole silicon tracking system as part of the Phase-2 Upgrade. About 8000 two co-planar strip sensor (2S) modules and 5880 macro-pixel and strip sensor (PS) modules will be built for the new Outer Tracker, requiring 47520 hybrid circuits. The mass production of hybrids has started. This paper will present the employed quality assurance procedures and report about issues observed so far. Measures to improve the production yield and the current status of the project will be presented
Large Hadron Collider Physics (LHCP) 2025 - Group Photo
No full textThe Thirteenth Annual Large Hadron Collider Physics (LHCP2025) conference took place in Taipei from 5th to 9th May 2025. The main goal of the conference is to provide intense and lively discussions between experimenters and theorists in such research areas as the Standard Model Physics and Beyond, the Higgs Boson, Heavy Quark Physics and Heavy Ion Physics as well as to share recent progress in the high luminosity upgrades and future collider developments
QCD/top physics: current status and prospects from the experiment side
No full textSlides for the talk at the CORFUFA25 workshop on future accelerator
LHC Abort Gap Monitor acquisition system
No full textThe Beam Dump System of the LHC Large Hadron Collider is one of its critical systems. It is responsible for changing the trajectory of the beam towards the beam dump. For its functionality it uses an Abort Gap - a space with no particles within a beam structure. This gap is formed during the injection of the particles into the LHC. The injection is never ideal hence Abort Gap always contains some particles. Energy accumulated in the Abort Gap can cause various damages and so its amount has to be continuously estimated. This is the purpose of an Abort Gap Monitor. The currently deployed Abort Gap Monitor uses analog integrators to measure the particle population. This makes the instrument difficult to calibrate due to its hardware inaccuracies. To improve the system measurement versatility and reproducibility the effort is made to create an acquisition system with digital integration. This work aims to design, verify and implement the digital acquisition system. The digital acquisition system serves as one of the major parts of the new CERN SY-BI group Abort Gap Monitor. This document is split into four sections. The first briefly describes the structure of the Beam Dump System and the importance of the Abort Gap. The second section explains the principle of Abort Gap measurements and the data evaluation methodology. The third section describes the current system design and its issues. Then it focuses on the new Abort Gap Monitor topology followed by acquisition system development. The last section presents the simulations and measurements obtained with the new Abort Gap Monitor Acquisition System and discusses further development steps
Recent results on ALPs from ATLAS
No full textSearches for axion-like-particles (ALPs) using LHC collision data at 13 TeV collected by the ATLAS experiment in Run 2. The searches cover a mass range of ALPs below the Z-boson mass. Novel reconstruction and identification techniques used in these searches are described