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Probing the nature of electroweak symmetry breaking with Higgs boson pair-production at ATLAS
No full textIn the Standard Model, the ground state of the Higgs field is not found at zero but instead corresponds to one of the degenerate solutions minimising the Higgs potential. In turn, this spontaneous electroweak symmetry breaking provides a mechanism for the mass generation of nearly all fundamental particles. The Standard Model makes a definite prediction for the Higgs boson self-coupling and thereby the shape of the Higgs potential. Experimentally, both can be probed through the production of Higgs boson pairs (HH), a rare process that presently receives a lot of attention at the LHC. In this talk, the latest HH searches by the ATLAS experiment are reported, with emphasis on the results obtained with the full LHC Run 2 dataset at 13 TeV. Non-resonant HH search results are interpreted both in terms of sensitivity to the Standard Model and as limits on the Higgs boson self-coupling and the quartic VVHH coupling. The Higgs boson self-coupling can be also constrained by exploiting higher-order electroweak corrections to single Higgs boson production. A combined measurement of both results yields the overall highest precision, and reduces model dependence by allowing for the simultaneous determination of the single Higgs boson couplings. Additionally, extrapolations of recent HH results towards the High Luminosity LHC upgrade are also discussed. Many new physics models predict the existence of resonances decaying into two bosons, including the Higgs boson or new scalar S bosons making these important signatures in the search for new physics. Searches for HH or SH resonances have been performed in various final states. In some of these searches, jet substructure techniques are used to disentangle the hadronic decay products in highly boosted configurations.Recent ATLAS searches with Run 2 data collected at the LHC and explains the experimental methods used, including vector- and Higgs-boson-tagging techniques are presented
Azimuthal anisotropy of prompt Ds mesons at sqrt(sNN) = 5.02 TeV with CMS experiment
No full textThe azimuthal anisotropy of prompt mesons in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is measured using data obtained with the CMS detector. The dataset corresponds to an integrated luminosity of 0.58 . The and Fourier coefficients are studied as a function of the transverse momentum (). The coefficient is determined in the range GeV/c for three event centrality ranges, while the coefficient is measured in the range GeV/c for one event centrality range. The results align with those observed for mesons, suggesting that the inclusion of a strange quark in the meson has a minimal impact on the flow coefficients when these are compared to the non-strange meson within the measured range of the analysis
Observation of a family of all-charm tetraquark candidates at the LHC
No full textThree structures, , , and , have been reported in the channel. These are prime candidates for all-charm tetraquarks. We extend our earlier study of these structures in proton-proton collisions using the CMS detector at the LHC, with 3.6 times more pairs ( of total integrated luminosity). The statistical uncertainties on the masses and widths are reduced by about a factor of three, and the systematic uncertainties are also substantially reduced. For the first time all three structures are established with a significance well above five standard deviations (). Good descriptions of the spectrum were based on quantum interference among structures, which is now validated with significances of more than relative to the fit with no interference---implying all structures have the same quantum numbers, and suggests a family of states
CERN Tape Archive Workshop : CTA 2025
No full textThe CERN Tape Archive (CTA) was designed to meet the demands of data archival from the LHC experiments, in terms of both data volume and throughput. In order to ingest data at the rates demanded by the LHC data acquisition (DAQ) systems, the system is built on EOS and CTA's scalable architecture principles. To optimise the performance of both disk and tape hardware and to achieve the desired I/O rates, the hardware must be provisioned appropriately. This talk will present a high-level view of the global CERN tape service configuration and dive into the details of how the required performance is achieved. We start from benchmarks of the SSDs used as the building blocks for the tape buffer and work up to the full service configuration, based on commodity hardware as used at CERN/WLCG Tier-0. This talk aims to outline the factors that a Tier-1 site who wants to deploy CTA should take into consideration
Performance and calibration of the ATLAS Tile Calorimeter
No full textThe Tile Calorimeter (TileCal) is a sampling hadronic calorimeter covering the central region of the ATLAS experiment, with steel as absorber and plastic scintillators as active medium. The scintillators are read-out by the wavelength shifting fibres coupled to the photomultiplier tubes (PMTs). The analogue signals from the PMTs are amplified, shaped, digitized by sampling the signal every 25 ns and stored on detector until a trigger decision is received. The TileCal front-end electronics reads out the signals produced by about 10000 channels measuring energies ranging from about 30 MeV to about 2 TeV. Each stage of the signal production from scintillation light to the signal reconstruction is monitored and calibrated. During LHC Run-2, high-momentum isolated muons have been used to study and validate the electromagnetic scale, while hadronic response has been probed with isolated hadrons. The calorimeter time resolution has been studied with multi-jet events. First results using early LHC Run-3 data will be shown. A summary of the performance results, including the calibration, stability, absolute energy scale, uniformity and time resolution, will be presented
LHCb Bottomonium production measurements in small systems at LHCb
No full textBottomonium production is sensitive to both the structure of nucleons and the interactions of b quarks with the nuclear media produced in heavy-ion collisions. The LHCb detector’s forward geometry allows for studying bottomonium production in a unique kinematic regime. Recent LHCb studies of bottomonium production will be presented, including multiplicity-dependent measurements sensitive to final-state effects and multi-parton interactions in small collision systems
