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Measurement of meson production in pp and p-Pb collisions at = 5.02 TeV
No full textWe present the measurement of the -differential production cross section of mesons in pp and p-Pb collisions at = 5.02 TeV at midrapidity by ALICE. In addition, the first measurement of the nuclear modification factor for mesons at LHC energies is presented, complementing the existing measurements of lighter neutral mesons such as the and . Within the measured -range, the of mesons shows no cold nuclear matter effects within the uncertainties, consistent with previous measurements at lower energies. The ratio is presented for both collision systems, showing no collision system dependence within the uncertainties. The comparison to previously published ratios at lower and higher collision energies in pp collisions suggests a decreasing trend of the ratio above GeV/ with increasing collision energy. The data in both collision systems are compared to predictions from PYTHIA 8, EPOS LHC and DPMJET event generators, revealing significant shortcomings in these models' ability to describe the production of mesons.We present the measurement of the pT-differential production cross section of ω mesons in pp and p-Pb collisions at sNN=5.02 TeV at midrapidity by ALICE. In addition, the first measurement of the nuclear modification factor RpPb for ω mesons at LHC energies is presented, complementing the existing measurements of lighter neutral mesons such as the π0 and η. Within the measured pT range, the RpPb of ω mesons is compatible with no cold nuclear matter effects within the uncertainties, consistent with previous measurements at lower energies. The ω/π0 ratio is presented for both collision systems, showing no collision system dependence within the uncertainties. The comparison to previously published ω/π0 ratios at lower and higher collision energies in pp collisions suggests a decreasing trend of the ratio above pT = 4 GeV/c with increasing collision energy. The data in both collision systems are compared to predictions from PYTHIA 8, EPOS LHC, and DPMJET event generators, revealing significant shortcomings in these models’ ability to describe the production of ω mesons.We present the measurement of the -differential production cross section of mesons in pp and pPb collisions at TeV at midrapidity by ALICE. In addition, the first measurement of the nuclear modification factor for mesons at LHC energies is presented, complementing the existing measurements of lighter neutral mesons such as the and . Within the measured -range, the of mesons is compatible with no cold nuclear matter effects within the uncertainties, consistent with previous measurements at lower energies. The ratio is presented for both collision systems, showing no collision system dependence within the uncertainties. The comparison to previously published ratios at lower and higher collision energies in pp collisions suggests a decreasing trend of the ratio above GeV/ with increasing collision energy. The data in both collision systems are compared to predictions from PYTHIA, EPOS LHC and DPMJET event generators, revealing significant shortcomings in these models' ability to describe the production of mesons
Quality Control setups description of GEM detector for CMS experiment
No full textThe CMS experiment at CERN is foreseen to receive a substantial upgrade during Long Shutdown-3 (LS3) to handle the large number of pileup events in the High-Luminosity LHC. The objective is to increase the integrated luminosity by a factor of 10 beyond the LHC's design value (). CMS just commissioned the Gaseous Electron Multiplier (GEM) detector, namely GE1/1, at the endcap during LS2. For Phase-2 upgrades, CMS has outlined plans for further endcap upgrades, such as GE2/1 and ME0 detectors, as part of the LS3 upgrade. For these detectors, the part of the detector assembly and all quality controls (QCs) are expected to take place at different production sites including Panjab University India, before sending them to CERN for installation at the CMS Experiment. This contribution will describe these QC tests (QC2 to QC5), their setups at production site and corresponding results of the triple GEM detector testing
Success, Open Source and You: Maximising the impact of your open-source contributions
No full textDiscover the diverse open-source contributions made by members of the CERN community! In this session, speakers will share their experiences working on projects that are not directly managed by CERN, showcasing the broader impact of their work and inspiring others to get involved
CMS iRPC RE-4/1 installation - YETS 2025
No full textIncredible and unique moment in lifetime!!! As of 21st February 2025, installation of the half of the 4 endcap disks is completed. In view of the High Luminosity upgrade of the CERN LHC, the forward CMS Muon spectrometer will be extended with two new stations of improved Resistive Plate Chambers (iRPC) covering the pseudorapidity range from 1.8 to 2.4. Compared to the present RPC system, the gap thickness is reduced to lower the avalanche charge, and an innovative 2D strip readout geometry is proposed
Initial-state-driven spin correlations in high-energy nuclear collisions
No full textIn the study of spin-polarization phenomena in heavy-ion collisions, it is typically assumed that final-state particles are polarized through thermal vorticity and shear. In this sense, polarization is a final-state effect. Here, we propose a different mechanism. We postulate that the collision of spin-carrying nucleons generates an initial transverse spin density, inducing a net polarization of the QCD fireball along a random direction. If the net spin is conserved throughout the evolution of the fireball, the final-state particles should exhibit measurable polarization. Within a wounded nucleon picture, we estimate that initial-state fluctuations induce a net polarization of baryons which is around in central collisions and over in noncentral collisions, significantly exceeding the contributions from thermal vorticity and shear. We introduce a two-particle angular correlation observable designed to reveal initial net-spin fluctuations, and emphasize the main signatures to look for in experiments. We argue that the discovery of these phenomena would have profound implications for nuclear structure and our understanding of spin in relativistic hydrodynamics
(Re)interpretation of the LHC results for new physics
No full textWe discuss a class of theories that predict a fermionic dark matter candidate from gauge anomaly cancellation. As an explicit example, we study the predictions in theories where the global symmetry associated with baryon number is promoted to a local gauge symmetry. In this context, the symmetry-breaking scale has to be below the multi-TeV scale in order to be in agreement with the cosmological constraints on the dark matter relic density. The new physical “Cucuyo” Higgs boson in the theory has very interesting properties, decaying mainly into two photons in the low mass region, and mainly into dark matter in the intermediate mass region. We study the most important signatures at the Large Hadron Collider, evaluating the experimental bounds. We discuss the correlation between the dark matter relic density, direct detection, and collider constraints. We find that these theories are still viable and are susceptible to being probed in current, and future high-luminosity, running
(Re)interpretation of the LHC results for new physics
No full textFor the development of modern event generators, the comparison to data is an invaluable tool for the tuning and validation of the code. I will review efforts where the comparisons to data from past colliders have allowed for improvements and extensions of event generators, with an emphasis on photoproduction and hard diffraction at HERA
(Re)interpretation of the LHC results for new physics
No full textIn recent years, LHC experiments are increasingly publishing the full likelihood models for statistical analysis in HEPData. For the purporse of reproducing and reinterpreting such analyses, it is essential to understand the contents of these statistical workspaces. As part of the validation process for an ATLAS combination of searches for Beyond-Standard-Model particles, I have developed an open-access web-based interface to easily and quickly visualise workspace contents and perform fits, called "WorkspaceExplorer", which is freely available at workspaceexplorer.app.cern.ch. In addition to validation, it can be a convenient tool for exploration of unfamiliar statistical models, lowering the barrier for using these for reinterpretations. In this talk, I will present available features and discuss possible use cases for the tool as well as the potential for further developments
Report Accelerator Complex Availability 2024
No full textThis document summarises the availability of the CERN Accelerator Complex during 2024. This note has been produced and ratified by the Reliability and Availability Working Group (RAWG) [1], which has compiled fault information for the period in question using the Accelerator Fault Tracker (AFT) [2]
WLCG Data Challenge 24
No full textDuring Run-3 the Large Hadron Collider (LHC) experiments are transferring up to 10PB of data daily across the Worldwide LHC Computing Grid (WLCG) sites. However, following the transition from Run-3 to Run-4, data volumes are expected to increase tenfold. The WLCG Data Challenge aims to address this significant scaling challenge through a series of rigorous test events.The primary objective of the 2024 Data Challenge (DC24) was to achieve 25\% of the anticipated bulk transfer rate required for Run-4. Six experiments participated the four LHC experiments --- ATLAS, CMS, LHCb, and ALICE --- as well as Belle II and DUNE. These experiments utilize the same networks, many of the same sites and the data management tools, that will be employed in Run-4. Additionally, DC24 aimed to test new technologies such as token-based authorization and advanced network monitoring tools.The direct benefits of DC24 included identifying bottlenecks within the centralized data management systems of each experiment, gaining experience with significantly higher data transfer rates, and fostering significant collaboration among experiments and stakeholders. These stakeholders encompassed site administrators, storage technology providers, network experts, and middleware tool developers, all contributing to the preparedness for the demands of Run-4