Search results for "CLEAR"
showing 10 items of 27042 documents
Investigations of Anisotropic Flow Using Multiparticle Azimuthal Correlations in pp, p-Pb, Xe-Xe, and Pb-Pb Collisions at the LHC
2019
Measurements of anisotropic flow coefficients ($v_n$) and their cross-correlations using two- and multi-particle cumulant methods are reported in collisions of pp at $\sqrt{s} = 13$ TeV, p-Pb at $\sqrt{s_{_{\rm NN}}} = 5.02$ TeV, Xe-Xe at $\sqrt{s_{_{\rm NN}}} = 5.44$ TeV, and Pb-Pb at $\sqrt{s_{_{\rm NN}}} = 5.02$ TeV recorded with the ALICE detector. The multiplicity dependence of $v_n$ is studied in a very wide range from 20 to 3000 particles produced in the mid-rapidity region $|��|<0.8$ for the transverse momentum range $0.2 < p_{\rm T} < 3.0$ GeV/$c$. An ordering of the coefficients $v_2 > v_3 > v_4$ is found in pp and p-Pb collisions, similar to that seen in large coll…
First measurement of quarkonium polarization in nuclear collisions at the LHC
2021
The polarization of inclusive J/$\psi$ and $\Upsilon(1{\rm S})$ produced in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region $2.5<y<4$ and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters $\lambda_{\theta}$, $\lambda_{\phi}$ and $\lambda_{\theta\phi}$ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval $2<p_{\rm T}<10$ GeV/$c$ and $p_{\rm T}<15$ GeV/$c$ for the J/$\psi$ and $\Upsilon(1{\rm S})$, respectively. The polarization parameter…
Inclusive cross section and double-helicity asymmetry for π0 production at midrapidity in p+p collisions at √s = 510 GeV
2016
PHENIX measurements are presented for the cross section and double-helicity asymmetry (ALL) in inclusive π0 production at midrapidity from p þ p collisions at ffiffi s p ¼ 510 GeV from data taken in 2012 and 2013 at the Relativistic Heavy Ion Collider. The next-to-leading-order perturbative-quantumchromodynamics theory calculation is in excellent agreement with the presented cross section results. The calculation utilized parton-to-pion fragmentation functions from the recent DSS14 global analysis, which prefer a smaller gluon-to-pion fragmentation function. The π0ALL results follow an increasingly positive asymmetry trend with pT and ffiffi s p with respect to the predictions and are in ex…
Cross section and longitudinal single-spin asymmetry AL for forward W±→μ±ν production in polarized p+p collisions at √s = 510 GeV
2018
We have measured the cross section and single-spin asymmetries from forward W ± → μ ± ν production in longitudinally polarized p + p collisions at √ s = 510 GeV using the PHENIX detector at the Relativistic Heavy Ion Collider. The cross sections are consistent with previous measurements at this collision energy, while the most forward and backward longitudinal single spin asymmetries provide new insights into the sea quark helicities in the proton. The charge of the W bosons provides a natural flavor separation of the participating partons. peerReviewed
Centrality dependence of charged jet production in p–Pb collisions at √sNN = 5.02 TeV
2016
Measurements of charged jet production as a function of centrality are presented for p–Pb collisions recorded at √sNN = 5.02 TeV with the ALICE detector. Centrality classes are determined via the energy deposit in neutron calorimeters at zero degree, close to the beam direction, to minimise dynamical biases of the selection. The corresponding number of participants or binary nucleon–nucleon collisions is determined based on the particle production in the Pb-going rapidity region. Jets have been reconstructed in the central rapidity region from charged particles with the anti-kT algorithm for resolution parameters R = 0.2 and R = 0.4 in the transverse momentum range 20 to 120 GeV/c. The reco…
Neutral pion and η meson production in p–Pb collisions at √sNN = 5.02 TeV
2018
Neutral pion and η meson invariant differential yields were measured in non-single diffractive p–Pb collisions at √sNN = 5.02 TeV with the ALICE experiment at the CERN LHC. The analysis combines results from three complementary photon measurements, utilizing the PHOS and EMCal calorimeters and the Photon Conversion Method. The invariant differential yields of π0 and η meson inclusive production are measured near mid-rapidity in a broad transverse momentum range of 0.3 4 GeV/c at 0.483 ± 0.015stat ± 0.015sys. A deviation from mT scaling is observed for pT < 2 GeV/c. The measured η/π0 ratio is consistent with previous measurements from proton-nucleus and pp collisions over the full pT range. …
Multipion Bose-Einstein correlations in pp,p-Pb, and Pb-Pb collisions at energies available at the CERN Large Hadron Collider
2016
Three- and four-pion Bose-Einstein correlations are presented in pp, p-Pb, and Pb-Pb collisions at the LHC. We compare our measured four-pion correlations to the expectation derived from two- and three-pion measurements. Such a comparison provides a method to search for coherent pion emission. We also present mixed-charge correlations in order to demonstrate the effectiveness of several analysis procedures such as Coulomb corrections. Same-charge four-pion correlations in pp and p-Pb appear consistent with the expectations from three-pion measurements. However, the presence of non-negligible background correlations in both systems prevent a conclusive statement. In Pb-Pb collisions, we obse…
Prompt and non-prompt J/ψ production and nuclear modification at mid-rapidity in p–Pb collisions at √sNN = 5.02 TeV
2018
A measurement of beauty hadron production at mid-rapidity in proton-lead collisions at a nucleon–nucleon centre-of-mass energy √sNN = 5.02 TeV is presented. The semi-inclusive decay channel of beauty hadrons into J/ψ is considered, where the J/ψ mesons are reconstructed in the dielectron decay channel at mid-rapidity down to transverse momenta of 1.3 GeV/c. The bb production cross section at mid-rapidity, dσbb /dy, and the total cross section extrapolated over full phase space, σbb¯, are obtained. This measurement is combined with results on inclusive J/ψ production to determine the prompt J/ψ cross sections. The results in p–Pb collisions are then scaled to expectations from pp collisions …
π0 and η meson production in proton-proton collisions at √s = 8 TeV
2018
An invariant differential cross section measurement of inclusive π0 and η meson production at mid-rapidity in pp collisions at s√=8 TeV was carried out by the ALICE experiment at the LHC. The spectra of π0 and η mesons were measured in transverse momentum ranges of 0.33.5 GeV/c . However, a deviation from this empirical scaling rule is observed for transverse momenta below p T <3.5 GeV/c in the η/π0 ratio with a significance of 6.2σ. peerReviewed
Multiplicity dependence of charged pion, kaon, and (anti)proton production at large transverse momentum in p–Pb collisions at √sNN = 5.02 TeV
2016
The production of charged pions, kaons and (anti)protons has been measured at mid-rapidity (−0.5 10 GeV/c), the particle ratios are consistent with those reported for pp and Pb–Pb collisions at the LHC energies. At intermediate pT the (anti)proton RpPb shows a Cronin-like enhancement, while pions and kaons show little or no nuclear modification. At high pT the charged pion, kaon and (anti)proton RpPb are consistent with unity within statistical and systematic uncertainties. peerReviewed