Measurements of inclusive J/ production at midrapidity and forward rapidity in PbPb collisions at = 5.02 TeV

Journal of High Energy Physics

Correlations in azimuthal angle extending over a long range in pseudorapidity between particles, usually called the “ridge” phenomenon, were discovered in heavy-ion collisions, and later found in pp and p–Pb collisions. In large systems, they are thought to arise from the expansion (collective flow) of the produced particles. Extending these measurements over a wider range in pseudorapidity and final-state particle multiplicity is important to understand better the origin of these long-range correlations in small collision systems. In this Letter, measurements of the long-range correlations in p–Pb collisions at= 5. 02 TeV are extended to a pseudorapidity gap of∆ η~ 8 between particles using the ALICE forward multiplicity detectors. After suppressing non-flow correlations, eg, from jet and resonance decays, the ridge structure is observed to persist up to a very large gap of∆ η~ 8 for the first time in p–Pb collisions …

Physics Letters B

The pseudorapidity dependence of elliptic (v 2), triangular (v 3), and quadrangular (v 4) flow coefficients of charged particles measured in Pb–Pb collisions at a centre-of-mass energy per nucleon pair of s NN= 5.02 TeV and in Xe–Xe collisions at s NN= 5.44 TeV with ALICE at the LHC are presented. The measurements are performed in the pseudorapidity range− 3.5< η< 5 for various centrality intervals using two-and multi-particle cumulants with the subevent method. The flow probability density function (pdf) is studied with the ratio of flow coefficient v 2 calculated with four-and two-particle cumulant, and suggests that the variance of flow pdf is independent of pseudorapidity. The decorrelation of the flow vector in the longitudinal direction is probed using two-particle correlations. The results measured with respect to different reference regions in pseudorapidity exhibit differences, argued to be a result of saturating …

Physical Review C

The first measurements of K*(892) 0 resonance production as a function of charged-particle multiplicity in Xe-Xe collisions at s N N= 5.44 TeV and p p collisions at s= 5.02 TeV using the ALICE detector are presented. The resonance is reconstructed at midrapidity (| y|< 0.5) using the hadronic decay channel K* 0→ K±π∓. Measurements of transverse-momentum integrated yield, mean transverse-momentum, nuclear modification factor of K* 0, and yield ratios of resonance to stable hadron (K* 0/K) are compared across different collision systems (p p, p-Pb, Xe-Xe, and Pb-Pb) at similar collision energies to investigate how the production of K* 0 resonances depends on the size of the system formed in these collisions. The hadronic rescattering effect is found to be independent of the size of colliding systems and mainly driven by the produced charged-particle multiplicity, which is a proxy of the volume of produced …

Journal of High Energy Physics

Correlations in azimuthal angle extending over a long range in pseudorapidity between particles, usually called the “ridge” phenomenon, were discovered in heavy-ion collisions, and later found in pp and p–Pb collisions. In large systems, they are thought to arise from the expansion (collective flow) of the produced particles. Extending these measurements over a wider range in pseudorapidity and final-state particle multiplicity is important to understand better the origin of these long-range correlations in small collision systems. In this Letter, measurements of the long-range correlations in p–Pb collisions at= 5. 02 TeV are extended to a pseudorapidity gap of∆ η~ 8 between particles using the ALICE forward multiplicity detectors. After suppressing non-flow correlations, eg, from jet and resonance decays, the ridge structure is observed to persist up to a very large gap of∆ η~ 8 for the first time in p–Pb collisions …

arXiv preprint arXiv:2404.08317

The Spin Physics Detector collaboration proposes to install a universal detector in the second interaction point of the NICA collider under construction (JINR, Dubna) to study the spin structure of the proton and deuteron and other spin-related phenomena using a unique possibility to operate with polarized proton and deuteron beams at a collision energy up to 27 GeV and a luminosity up to cm s. As the main goal, the experiment aims to provide access to the gluon TMD PDFs in the proton and deuteron, as well as the gluon transversity distribution and tensor PDFs in the deuteron, via the measurement of specific single and double spin asymmetries using different complementary probes such as charmonia, open charm, and prompt photon production processes. Other polarized and unpolarized physics is possible, especially at the first stage of NICA operation with reduced luminosity and collision energy of the proton and ion beams. This document is dedicated exclusively to technical issues of the SPD setup construction.

Physics Letters B

In this Letter, the first measurement of the inelastic cross section for antitriton–nucleus interactions is reported, covering the momentum range of 0.8≤ p< 2.4 GeV/c. The measurement is carried out using data recorded with the ALICE detector in pp and Pb–Pb collisions at a centre-of-mass energy per nucleon of 13 TeV and 5.02 TeV, respectively. The detector material serves as an absorber for antitriton nuclei. The raw yield of (anti) triton nuclei measured with the ALICE apparatus is compared to the results from detailed ALICE simulations based on the Image 1 toolkit for the propagation of (anti) particles through matter, allowing one to quantify the inelastic interaction probability in the detector material. This analysis complements the measurement of the inelastic cross section of antinuclei up to A= 3 carried out by the ALICE Collaboration, and demonstrates the feasibility of the study of the isospin dependence of …

Physical Review C

The first measurements of K*(892) 0 resonance production as a function of charged-particle multiplicity in Xe-Xe collisions at s N N= 5.44 TeV and p p collisions at s= 5.02 TeV using the ALICE detector are presented. The resonance is reconstructed at midrapidity (| y|< 0.5) using the hadronic decay channel K* 0→ K±π∓. Measurements of transverse-momentum integrated yield, mean transverse-momentum, nuclear modification factor of K* 0, and yield ratios of resonance to stable hadron (K* 0/K) are compared across different collision systems (p p, p-Pb, Xe-Xe, and Pb-Pb) at similar collision energies to investigate how the production of K* 0 resonances depends on the size of the system formed in these collisions. The hadronic rescattering effect is found to be independent of the size of colliding systems and mainly driven by the produced charged-particle multiplicity, which is a proxy of the volume of produced …

The areas in which the Infrared (IR) spectrum gives vital information are as different as they are unique. However, this versatility comes with limitations. One of these obstacles is how to deal with the noise that affects this spectrum, which heavily distorts the data acquired from a scene. This investigation centers itself around how to fix the Fixed Pattern Noise (FPN) in the Short Wave Infrared (SWIR) using a refocusing algorithm, as an alternative of the two point black body calibration. Plants are chosen because of the ease to identify hidric stress in them using IR imaging due to the water natural reflectance and absorbance properties. The elimination of noise using this method will be revised, comparing it to the well known two point calibration method. Furthermore, by using filters a multispectral cube will be created and a spectral range of interest within the SWIR will be defined.

Physical Review C

The production cross section of inclusive J/ψ pairs in p p collisions at a center-of-mass energy s= 13 TeV is measured with ALICE. The measurement is performed for J/ψ in the rapidity interval 2.5< y< 4.0 and for transverse momentum p T> 0. The production cross section of inclusive J/ψ pairs is reported to be 10.3±2.3 (stat.)±1.3 (syst.) nb in this kinematic interval. The contribution from nonprompt J/ψ (ie, originated from beauty-hadron decays) to the inclusive sample is evaluated. The effective double-parton scattering cross section is computed, neglecting the single-parton scattering contribution.

IEEE Access

E-learning platforms are valuable tools to support and enhance the learning and teaching process during online classes. Even though these platforms are already well-known and have been widely used for a long time, transitioning to fully online activities with a large number of users can lead to an exponential growth in resource usage. Moreover, the availability of these platforms becomes critical since the learning activities cannot be interrupted, and the vital information (assignments, grades, and shared resources) cannot be lost. Thus, the system administrators must implement a scalable solution to accommodate many users and activities. Determining the most suitable architecture is a non-trivial task that must consider the various tools, services, and interconnect options that are available. This paper presents our approach to setting up an integrated high-workload e-learning setup used for online classes in …

Charged-particle jet yields have been measured in semicentral Pb–Pb collisions at center-of-mass energy per nucleon–nucleon collision

Physical Review C

The PHENIX experiment reports systematic measurements at the Relativistic Heavy Ion Collider of ϕ-meson production in asymmetric Cu+ Au collisions at s N N= 200 GeV and in U+ U collisions at s N N= 193 GeV. Measurements were performed via the ϕ→ K+ K− decay channel at midrapidity| η|< 0.35. Features of ϕ-meson production measured in Cu+ Cu, Cu+ Au, Au+ Au, and U+ U collisions were found to not depend on the collision geometry, which was expected because the yields are averaged over the azimuthal angle and follow the expected scaling with nuclear-overlap size. The elliptic flow of the ϕ meson in Cu+ Au, Au+ Au, and U+ U collisions scales with second-order-participant eccentricity and the length scale of the nuclear-overlap region (estimated with the number of participating nucleons). At moderate p T, ϕ-meson production measured in Cu+ Au and U+ U collisions is consistent with coalescence …

The European Physical Journal A

The interactions of kaons (K) and antikaons () with few nucleons (N) were studied so far using kaonic atom data and measurements of kaon production and interaction yields in nuclei. Some details of the three-body KNN and NN dynamics are still not well understood, mainly due to the overlap with multi-nucleon interactions in nuclei. An alternative method to probe the dynamics of three-body systems with kaons is to study the final state interaction within triplet of particles emitted in pp collisions at the Large Hadron Collider, which are free from effects due to the presence of bound nucleons. This Letter reports the first femtoscopic study of p–p–K and p–p–K correlations measured in high-multiplicity pp collisions at = 13 TeV by the ALICE Collaboration. The analysis shows that the measured p–p–K and p–p–K correlation functions can be interpreted in terms of pairwise interactions in the triplets …

The physics programme and scope of HEP experiments natu-rally grow with time, thus the computing requirements, both CPU and storage, increase. The 4 large LHC experiments (ALICE, ATLAS, CMS, and LHCb) are undergoing upgrade cycles, for ALICE and LHCb the upgrade was finalized in the years of the LHC long Shutdown 2, 2019–2021, and for ATLAS and CMS it is foreseen to take place in 2026–2028. The ALICE upgrade was characterized by a complete overhaul of the detector, data acquisition (DAQ) systems, and entire software stack. As a consequence, the experiment can take up to 100 times more events, compared to the previous setup, and is employing a new online data compression and calibration utility (O2) to reduce the data stream, which nonetheless is 4 times larger than before the upgrade. To manage the new more complex data paths, a new data management software was designed …

Physical Review C

This Letter reports on the first measurements of transverse momentum dependent flow angle Ψ n and flow magnitude v n fluctuations determined using new four-particle correlators. The measurements are performed for various centralities in Pb–Pb collisions at a center-of-mass energy per nucleon pair of s N N= 5.02 TeV with ALICE at the CERN Large Hadron Collider. Both flow angle and flow magnitude fluctuations are observed in the presented centrality ranges and are strongest in the most central collisions and for a transverse momentum p T> 2 GeV/c. Comparison with theoretical models, including iEBE-VISHNU, MUSIC, and AMPT, show that the measurements exhibit unique sensitivities to the initial state of heavy-ion collisions.

Physics letters B

This letter reports measurements which characterize the underlying event associated with hard scatterings at mid-pseudorapidity (| η|< 0.8) in pp, p–Pb and Pb–Pb collisions at centre-of-mass energy per nucleon pair, s NN= 5.02 TeV. The measurements are performed with ALICE at the LHC. Different multiplicity classes are defined based on the event activity measured at forward rapidities. The hard scatterings are identified by the leading particle defined as the charged particle with the largest transverse momentum (p T) in the collision and having 8< p T< 15 GeV/c. The p T spectra of associated particles (0.5≤ p T< 6 GeV/c) are measured in different azimuthal regions defined with respect to the leading particle direction: toward, transverse, and away. The associated charged particle yields in the transverse region are subtracted from those of the away and toward regions. The remaining jet-like yields are reported …

Journal of Physics: Conference Series

CERN experiments are preparing for the HL-LHC era, which will bring an unprecedented volume of scientific data. These data will need to be stored and processed by thousands of physicists, but expected resource growth is nowhere near the extrapolated requirements of existing models, in terms of both storage volume and compute power. Opportunistic CPU resources such as HPCs and university clusters can provide extra CPU cycles, but there is no opportunistic storage. In this article, we will present the main architectural ideas, deployment details, and test results, with emphasis on our research to build a prototype of a distributed data processing and storage system with a focus on optimizing the efficiency of resources by reducing overhead costs for accessing the data. The described prototype was built using the geographically distributed WLCG sites and university clusters in Russia.