83 research outputs found

    Modeling and Simulation of Microscale Flows

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    High Performance Heterogeneous Computing for Quantum Computing Simulations

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    This presentation, published by the Support Center for Microsystems Education (SCME), took place at the Micro Nano Technology Education Special Interest Group (MNTeSIG) Live 2021 conference. In the presentation, Auro Ashish Saha explores high performance heterogeneous computing for quantum computing simulations for training the quantum workforce. Saha highlights the need for quantum workforce training, skills and competencies, academic and professional research internships, and an implementation methodology. The video recording runs 27:18 minutes in length.&nbsp

    Simulation Design Framework for Multiscale Multiphysics Thermo Electric and Electro Chemical Transport

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    In this video, provided by the Support Center for Microsystems Education (SCME) at the annual MNTeSIG Live! 2022 virtual conference, Auro Ashish Saha from Puducherry Technological University explores nanoHUB btesolver and dualfoil resources that enable the study of thermo electric and electro chemical transport processes. A simulation design framework for optimizing the multiscale multiphysics thermo electric and electro chemical transport in their respective devices is highlighted. Phenomenological equations governing transport phenomena, a linearized Boltzmann transport calculator for thermo electric materials, Dualfoil.py, and an implementation methodology are also explored. The video recording runs 19:25 minutes in length

    Measurements of the groomed and ungroomed jet angularities in pp collisions at s \sqrt{s} = 5.02 TeV

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    International audienceThe jet angularities are a class of jet substructure observables which characterize the angular and momentum distribution of particles within jets. These observables are sensitive to momentum scales ranging from perturbative hard scatterings to nonperturbative fragmentation into final-state hadrons. We report measurements of several groomed and ungroomed jet angularities in pp collisions at s \sqrt{s} = 5.02 TeV with the ALICE detector. Jets are reconstructed using charged particle tracks at midrapidity (|η| < 0.9). The anti-kT_{T} algorithm is used with jet resolution parameters R = 0.2 and R = 0.4 for several transverse momentum {p}_{\mathrm{T}}^{\mathrm{ch}} ^{jet} intervals in the 20–100 GeV/c range. Using the jet grooming algorithm Soft Drop, the sensitivity to softer, wide-angle processes, as well as the underlying event, can be reduced in a way which is well-controlled in theoretical calculations. We report the ungroomed jet angularities, λα_{α}, and groomed jet angularities, λα,g_{α,g}, to investigate the interplay between perturbative and nonperturbative effects at low jet momenta. Various angular exponent parameters α = 1, 1.5, 2, and 3 are used to systematically vary the sensitivity of the observable to collinear and soft radiation. Results are compared to analytical predictions at next-to-leading-logarithmic accuracy, which provide a generally good description of the data in the perturbative regime but exhibit discrepancies in the nonperturbative regime. Moreover, these measurements serve as a baseline for future ones in heavy-ion collisions by providing new insight into the interplay between perturbative and nonperturbative effects in the angular and momentum substructure of jets. They supply crucial guidance on the selection of jet resolution parameter, jet transverse momentum, and angular scaling variable for jet quenching studies.[graphic not available: see fulltext

    Inclusive quarkonium production in pp collisions at s=5.02\sqrt{s} = 5.02 TeV

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    This article reports on the inclusive production cross section of several quarkonium states, J/ψ\mathrm{J}/\psi, ψ(2S)\psi {\rm (2S)}, Υ(1S)\Upsilon\rm(1S), Υ(2S)\Upsilon\rm(2S), and Υ(3S)\Upsilon\rm(3S), measured with the ALICE detector at the LHC, in \pp collisions at s=5.02\sqrt{s} = 5.02 TeV. The analysis is performed in the dimuon decay channel at forward rapidity (2.5<y<42.5 < y < 4). The measured cross sections, assuming unpolarized quarkonia, are: σJ/ψ=5.88±0.03±0.34 μ\sigma_{\mathrm{J}/\psi} = 5.88 \pm 0.03 \pm 0.34\ \mub, σψ(2S)=0.87±0.06±0.10 μ\sigma_{\psi {\rm (2S)}} = 0.87 \pm 0.06 \pm 0.10\ \mub, σΥ(1S)=45.5±3.9±3.5\sigma_{\Upsilon\rm(1S)} = 45.5 \pm 3.9 \pm 3.5 nb, σΥ(2S)=22.4±3.2±2.7\sigma_{\Upsilon\rm(2S)} = 22.4 \pm 3.2 \pm 2.7 nb, and σΥ(3S)=4.9±2.2±1.0\sigma_{\Upsilon\rm(3S)} = 4.9 \pm 2.2 \pm 1.0 nb, where the first (second) uncertainty is the statistical (systematic) one. The transverse-momentum (pTp_{\rm T}) and rapidity (yy) differential cross sections for J/ψ\mathrm{J}/\psi, ψ(2S)\psi {\rm (2S)}, Υ(1S)\Upsilon\rm(1S), and the ψ(2S)\psi {\rm (2S)}-to-J/ψ\mathrm{J}/\psi cross section ratios are presented. For the first time, the cross sections of the three Υ\Upsilon states, as well as the ψ(2S)\psi {\rm (2S)} one as a function of pTp_{\rm T} and yy, are measured at s=5.02\sqrt{s} = 5.02 TeV at forward rapidity. These measurements also significantly extend the J/ψ\mathrm{J}/\psipTp_{\rm T} reach with respect to previously published results. A comparison with ALICE measurements in pp collisions at s=2.76\sqrt{s} = 2.76, 7, 8, and 13 TeV is presented and the energy dependence of quarkonium production cross sections is discussed. Finally, the results are compared with the predictions from several production models

    Forward rapidity J/ψ production as a function of charged-particle multiplicity in pp collisions at s \sqrt{s} = 5.02 and 13 TeV

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    International audienceThe production of J/ψ is measured as a function of charged-particle multiplicity at forward rapidity in proton-proton (pp) collisions at center-of-mass energies s \sqrt{s} = 5.02 and 13 TeV. The J/ψ mesons are reconstructed via their decay into dimuons in the rapidity interval (2.5 < y < 4.0), whereas the charged-particle multiplicity density (dNch_{ch}/dη) is measured at midrapidity (|η| < 1). The production rate as a function of multiplicity is reported as the ratio of the yield in a given multiplicity interval to the multiplicity-integrated one. This observable shows a linear increase with charged-particle multiplicity normalized to the corresponding average value for inelastic events (dNch_{ch}/dη/〈dNch_{ch}/dη〉), at both the colliding energies. Measurements are compared with available ALICE results at midrapidity and theoretical model calculations. First measurement of the mean transverse momentum (〈pT_{T}〉) of J/ψ in pp collisions exhibits an increasing trend as a function of dNch_{ch}/dη/〈dNch_{ch}/dη〉 showing a saturation towards high charged-particle multiplicities.[graphic not available: see fulltext

    Polarization of Λ and ¯Λ hyperons along the beam direction in Pb–Pb collisions at √sNN = 5.02 TeV

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    The polarization of the Λ and Λ¯¯¯¯ hyperons along the beam (z) direction, Pz, has been measured in Pb-Pb collisions at sNN−−−√ = 5.02TeV recorded with ALICE at the Large Hadron Collider (LHC). The main contribution to Pz comes from elliptic flow induced vorticity and can be characterized by the second Fourier sine coefficient Pz,s2=⟨Pzsin(2φ−2Ψ2)⟩, where φ is the hyperon azimuthal emission angle, and Ψ2 is the elliptic flow plane angle. We report the measurement of Pz,s2 for different collision centralities, and in the 30-50% centrality interval as a function of the hyperon transverse momentum and rapidity. The Pz,s2 is positive similarly as measured by the STAR Collaboration in Au-Au collisions at sNN−−−√ = 200 GeV, with somewhat smaller amplitude in the semi-central collisions. This is the first experimental evidence of a non-zero hyperon Pz in Pb-Pb collisions at the LHC. The comparison of the measured Pz,s2 with the hydrodynamic model calculations shows sensitivity to the competing contributions from thermal and the recently found shear induced vorticity, as well as to whether the polarization is acquired at the quark-gluon plasma or the hadronic phase

    Inclusive quarkonium production in pp collisions at s=5.02\sqrt{s} = 5.02 TeV

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    This article reports on the inclusive production cross section of several quarkonium states, J/ψ\mathrm{J}/\psi, ψ(2S)\psi {\rm (2S)}, Υ(1S)\Upsilon\rm(1S), Υ(2S)\Upsilon\rm(2S), and Υ(3S)\Upsilon\rm(3S), measured with the ALICE detector at the LHC, in \pp collisions at s=5.02\sqrt{s} = 5.02 TeV. The analysis is performed in the dimuon decay channel at forward rapidity (2.5<y<42.5 < y < 4). The measured cross sections, assuming unpolarized quarkonia, are: σJ/ψ=5.88±0.03±0.34 μ\sigma_{\mathrm{J}/\psi} = 5.88 \pm 0.03 \pm 0.34\ \mub, σψ(2S)=0.87±0.06±0.10 μ\sigma_{\psi {\rm (2S)}} = 0.87 \pm 0.06 \pm 0.10\ \mub, σΥ(1S)=45.5±3.9±3.5\sigma_{\Upsilon\rm(1S)} = 45.5 \pm 3.9 \pm 3.5 nb, σΥ(2S)=22.4±3.2±2.7\sigma_{\Upsilon\rm(2S)} = 22.4 \pm 3.2 \pm 2.7 nb, and σΥ(3S)=4.9±2.2±1.0\sigma_{\Upsilon\rm(3S)} = 4.9 \pm 2.2 \pm 1.0 nb, where the first (second) uncertainty is the statistical (systematic) one. The transverse-momentum (pTp_{\rm T}) and rapidity (yy) differential cross sections for J/ψ\mathrm{J}/\psi, ψ(2S)\psi {\rm (2S)}, Υ(1S)\Upsilon\rm(1S), and the ψ(2S)\psi {\rm (2S)}-to-J/ψ\mathrm{J}/\psi cross section ratios are presented. For the first time, the cross sections of the three Υ\Upsilon states, as well as the ψ(2S)\psi {\rm (2S)} one as a function of pTp_{\rm T} and yy, are measured at s=5.02\sqrt{s} = 5.02 TeV at forward rapidity. These measurements also significantly extend the J/ψ\mathrm{J}/\psipTp_{\rm T} reach with respect to previously published results. A comparison with ALICE measurements in pp collisions at s=2.76\sqrt{s} = 2.76, 7, 8, and 13 TeV is presented and the energy dependence of quarkonium production cross sections is discussed. Finally, the results are compared with the predictions from several production models

    Neutral to charged kaon yield fluctuations in Pb – Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

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    We present the first measurement of event-by-event fluctuations in the kaon sector in Pb – Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV with the ALICE detector at the LHC. The robust fluctuation correlator νdyn_{dyn} is used to evaluate the magnitude of fluctuations of the relative yields of neutral and charged kaons, as well as the relative yields of charged kaons, as a function of collision centrality and selected kinematic ranges. While the correlator νdyn_{dyn}[K+^+,K^−] exhibits a scaling approximately in inverse proportion of the charged particle multiplicity, νdyn_{dyn}[KS0_S^0,K±^\pm] features a significant deviation from such scaling. Within uncertainties, the value of νdyn_{dyn}[KS0_S^0,K±^\pm] is independent of the selected transverse momentum interval, while it exhibits a pseudorapidity dependence. The results are compared with HIJING, AMPT and EPOS–LHC predictions, and are further discussed in the context of the possible production of disoriented chiral condensates in central Pb – Pb collisions

    First study of the two-body scattering involving charm hadrons

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    This article presents the first measurement of the interaction between charm hadrons and nucleons. The two-particle momentum correlations of pDpD^- and pˉD+\bar{p}D^+ pairs are measured by the ALICE Collaboration in high-multiplicity pp collisions at s\sqrt{s} = 13 TeV. The data are compatible with the Coulomb-only interaction hypothesis within (1.1–1.5)σ. The level of agreement slightly improves if an attractive nucleon (N)Dˉ(N)\bar{D} strong interaction is considered, in contrast to most model predictions which suggest an overall repulsive interaction. This measurement allows for the first time an estimation of the 68% confidence level interval for the isospin I=0 inverse scattering length of the NDˉN\bar{D} state f0,I=01f_{0,I=0}^{-1}∈[-0.4,0.9] fm1^{-1}, assuming negligible interaction for the isospin I=1 channel
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