258 research outputs found

    Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

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    Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 <pT,assoc<pT,trig< < p_{\rm{T}, assoc} < p_{\rm{T}, trig} < 5.0 GeV/cc is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range ∣η∣<0.9|\eta|<0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

    Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

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    Measurements of multi-particle azimuthal correlations (cumulants) for charged particles in p-Pb and Pb-Pb collisions are presented. They help address the question of whether there is evidence for global, flow-like, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a âˆŁÎ”Î·âˆŁ|\Delta \eta| gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high-multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of v2{4}v_{2}\{4\} to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find v2{4}≃v2{6}≠0v_{2}\{4\} \simeq v_{2}\{6\}\neq 0 which is indicative of a Bessel-Gaussian function for the v2v_{2} distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a âˆŁÎ”Î·âˆŁ>1.4|\Delta\eta| > 1.4 gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87

    АĐșŃ‚ŃƒĐ°Đ»ŃŒĐœŃ– ĐżĐžŃ‚Đ°ĐœĐœŃ рДалізації Ń–ĐżĐŸŃ‚Đ”Ń‡ĐœĐžŃ… Đ·ĐŸĐ±ĐŸĐČ'ŃĐ·Đ°ĐœŃŒ ĐČ ĐœĐŸŃ‚Đ°Ń€Ń–Đ°Đ»ŃŒĐœĐŸĐŒŃƒ ĐżŃ€ĐŸŃ†Đ”ŃŃ–

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    Стаття просĐČŃŃ‡Đ”ĐœĐ° Ń‚Đ”ĐŸŃ€Đ”Ń‚ĐžŃ‡ĐœĐŸĐŒŃƒ ĐŽĐŸŃĐ»Ń–ĐŽĐ¶Đ”ĐœĐœŃŽ ĐČажлОĐČĐŸŃŃ‚Ń– ĐČĐžĐșĐŸŃ€ĐžŃŃ‚Đ°ĐœĐœŃ Ń–ŃĐœŃƒŃŽŃ‡ĐžŃ… ĐŒĐ”Ń…Đ°ĐœŃ–Đ·ĐŒŃ–ĐČ ĐżŃ€Đ”ĐČĐ”ĐœŃ‚ĐžĐČĐœĐŸŃ— юстоції та ЮієĐČĐŸŃŃ‚Ń– праĐČĐŸĐ·Đ°Ń…ĐžŃĐœĐŸŃ— Ń„ŃƒĐœĐșції ĐœĐŸŃ‚Đ°Ń€Ń–Đ°Ń‚Ńƒ. Đ”ĐŸĐČĐ”ĐŽĐ”ĐœĐŸ, Ń‰ĐŸ ĐœĐŸŃ‚Đ°Ń€Ń–ŃƒŃ яĐș ĐłĐ°Ń€Đ°ĐœŃ‚ прДĐČĐ”ĐœŃ‚ĐžĐČĐœĐŸŃŃ‚Ń– праĐČĐŸĐČŃ–ĐŽĐœĐŸŃĐžĐœ Ń€Đ”Đ°Đ»Ń–Đ·ŃƒŃ” сĐČĐŸŃ— праĐČĐŸĐ·Đ°Ń…ĐžŃĐœŃ– Ń„ŃƒĐœĐșції ĐœĐ” лОшД ĐœĐ° стаЮії рДалізації Ń–ĐżĐŸŃ‚Đ”Ń‡ĐœĐžŃ… Đ·ĐŸĐ±ĐŸĐČŃĐ·Đ°ĐœŃŒ, ŃˆĐ»ŃŃ…ĐŸĐŒ ĐČŃ‡ĐžĐœĐ”ĐœĐœŃ ĐČĐžĐșĐŸĐœĐ°ĐČŃ‡ĐŸĐłĐŸ ĐœĐ°ĐżĐžŃŃƒ ĐœĐ° Đ±ĐŸŃ€ĐłĐŸĐČĐŸĐŒŃƒ ĐŽĐŸĐșŃƒĐŒĐ”ĐœŃ‚Ń–, Đ° і ĐœĐ° стаЮії ŃƒĐ·ĐłĐŸĐŽĐ¶Đ”ĐœĐœŃ та ĐČĐžĐșĐ»Đ°ĐŽĐ”ĐœĐœŃ ĐČсіх Ń–ŃŃ‚ĐŸŃ‚ĐœĐžŃ… ŃƒĐŒĐŸĐČ ĐŽĐŸĐłĐŸĐČĐŸŃ€Ńƒ. ĐšĐ»ŃŽŃ‡ĐŸĐČі ŃĐ»ĐŸĐČĐ°: ĐœĐŸŃ‚Đ°Ń€Ń–Đ°Ń‚; праĐČĐŸĐ·Đ°Ń…ĐžŃĐœĐ° Ń„ŃƒĐœĐșція ĐœĐŸŃ‚Đ°Ń€Ń–Đ°Ń‚Ńƒ; ĐČĐžĐșĐŸĐœĐ°ĐœĐœŃ Đ·ĐŸĐ±ĐŸĐČŃĐ·Đ°ĐœŃŒ; прДĐČĐ”ĐœŃ‚ĐžĐČĐœĐ° юстоція.Статья ĐżĐŸŃĐČŃŃ‰Đ”ĐœĐ° Ń‚Đ”ĐŸŃ€Đ”Ń‚ĐžŃ‡Đ”ŃĐșĐŸĐŒŃƒ ĐžŃŃĐ»Đ”ĐŽĐŸĐČĐ°ĐœĐžŃŽ ĐœĐ”ĐŸĐ±Ń…ĐŸĐŽĐžĐŒĐŸŃŃ‚Đž ĐžŃĐżĐŸĐ»ŃŒĐ·ĐŸĐČĐ°ĐœĐžŃ ŃŃƒŃ‰Đ”ŃŃ‚ĐČующох ĐŒĐ”Ń…Đ°ĐœĐžĐ·ĐŒĐŸĐČ ĐżŃ€Đ”ĐČĐ”ĐœŃ‚ĐžĐČĐœĐŸĐč юстоцоо Đž ĐŽĐ”ĐčстĐČĐ”ĐœĐœĐŸŃŃ‚Đž праĐČĐŸĐ·Đ°Ń‰ĐžŃ‚ĐœĐŸĐč Ń„ŃƒĐœĐșцоо ĐœĐŸŃ‚Đ°Ń€ĐžĐ°Ń‚Đ°. Đ”ĐŸĐșĐ°Đ·Ń‹ĐČĐ°Đ”Ń‚ŃŃ, Ń‡Ń‚ĐŸ ĐœĐŸŃ‚Đ°Ń€ĐžŃƒŃ ĐșĐ°Đș ĐłĐ°Ń€Đ°ĐœŃ‚ прДĐČĐ”ĐœŃ‚ĐžĐČĐœĐŸŃŃ‚Đž праĐČĐŸĐŸŃ‚ĐœĐŸŃˆĐ”ĐœĐžĐč Ń€Đ”Đ°Đ»ĐžĐ·ŃƒĐ”Ń‚ сĐČĐŸĐž праĐČĐŸĐ·Đ°Ń‰ĐžŃ‚ĐœŃ‹Đ” Ń„ŃƒĐœĐșцоо ĐœĐ” Ń‚ĐŸĐ»ŃŒĐșĐŸ ĐœĐ° стаЮоо рДалОзацОО ĐžĐżĐŸŃ‚Đ”Ń‡ĐœŃ‹Ń… ĐŸĐ±ŃĐ·Đ°Ń‚Đ”Đ»ŃŒŃŃ‚ĐČ, ĐČ ŃĐČŃĐ·Đž с ŃĐŸĐČĐ”Ń€ŃˆĐ”ĐœĐžĐ”ĐŒ ĐžŃĐżĐŸĐ»ĐœĐžŃ‚Đ”Đ»ŃŒĐœĐŸĐč ĐœĐ°ĐŽĐżĐžŃĐž ĐœĐ° ĐŽĐŸĐ»ĐłĐŸĐČĐŸĐŒ ĐŽĐŸĐșŃƒĐŒĐ”ĐœŃ‚Đ”, Đ° Đž ĐœĐ° стаЮоо ŃĐŸĐłĐ»Đ°ŃĐŸĐČĐ°ĐœĐžŃ Đž ĐžĐ·Đ»ĐŸĐ¶Đ”ĐœĐžŃ ĐČсДх ŃŃƒŃ‰Đ”ŃŃ‚ĐČĐ”ĐœĐœŃ‹Ń… ŃƒŃĐ»ĐŸĐČĐžĐč ĐŽĐŸĐłĐŸĐČĐŸŃ€Đ°. КлючДĐČŃ‹Đ” ŃĐ»ĐŸĐČĐ°: ĐœĐŸŃ‚Đ°Ń€ĐžĐ°Ń‚; праĐČĐŸĐ·Đ°Ń‰ĐžŃ‚ĐœĐ°Ń Ń„ŃƒĐœĐșцоя ĐœĐŸŃ‚Đ°Ń€ĐžĐ°Ń‚Ńƒ; ĐžŃĐżĐŸĐ»ĐœĐ”ĐœĐžĐ” ĐŸĐ±ŃĐ·Đ°Ń‚Đ”Đ»ŃŒŃŃ‚ĐČ; прДĐČĐ”ĐœŃ‚ĐžĐČĐœĐ°Ń юстоцоя.This article is dedicated into theoretical research of importance in using special mechanism of prevention justitia and acting law defender functions of notoriety. It is argued that notaries as a guaranty of prevention law relation realizes his law defender functions not only on the stage of realization ipothek obligations, making performance inscription on the duty document, but on the stage of consenting and stating all existence conditions of contract. Key words: notoriety, law defender function of notaries, making obligations, prevention justitia

    K0S and Λ production in Pb-Pb collisions at sNN−−−−√=2.76  TeV

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    The ALICE measurement of K0S and Λ production at midrapidity in Pb-Pb collisions at sNN−−−√=2.76  TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4  GeV/c (0.6  GeV/c for Λ) to 12  GeV/c. The pT dependence of the Λ/K0S ratios exhibits maxima in the vicinity of 3  GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at s√=0.9  TeV and at s√=7  TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2  GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the Λ/K0S ratio

    phi-Meson production at forward rapidity in p-Pb collisions at root s(NN)=5.02 TeV and in pp collisions at root s=2.76 TeV

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    The first study of phi-meson production in p-Pb collisions at forward and backward rapidity, at a nucleonnucleon centre-of-mass energy root s(NN)= 5.02 TeV, has been performed with the ALICE apparatus at the LHC. The phi-mesons have been identified in the dimuon decay channel in the transverse momentum (p(T)) range 1 <p(T) <7GeV/c, both in the p-going (2.03 <y <3.53) and the Pb-going (-4.46 <y <-2.96) directions - where ystands for the rapidity in the nucleon-nucleon centre-of-mass - the integrated luminosity amounting to 5.01 +/- 0.19nb(-1) and 5.81 +/- 0.20nb(-1), respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward ratio for f-meson production is measured for 2.96Peer reviewe

    One-dimensional pion, kaon, and proton femtoscopy in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

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    The size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of pi(+/-) pi(+/-), K-+/- K-+/-, K-S(0) K-S(0), pp, and (pp) over bar correlations from Pb-Pb collisions at root s(NN) = 2.76 TeV by the ALICE experiment at the LHC. One-dimensional radii of the system are extracted from correlation functions in terms of the invariant momentum difference of the pair. The comparison of the measured radii with the predictions from a hydrokinetic model is discussed. The pion and kaon source radii display a monotonic decrease with increasing average pair transverse mass m(T) which is consistent with hydrodynamic model predictions for central collisions. The kaon and proton source sizes can be reasonably described by approximate m(T) scaling.Peer reviewe

    Charged jet cross sections and properties in proton-proton collisions at root s=7 TeV

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    The differential charged jet cross sections, jet fragmentation distributions, and jet shapes are measured in minimum bias proton-proton collisions at center-of-mass energy root s = 7 TeV using the ALICE detector at the LHC. Jets are reconstructed from charged particle momenta in the midrapidity region using the sequential recombination k(T) and anti-k(T) as well as the SISCone jet finding algorithms with several resolution parameters in the range R = 0.2-0.6. Differential jet production cross sections measured with the three jet finders are in agreement in the transverse momentum (p(T)) interval 20 ) of the reconstructed jet p(T). The fragmentation of leading jets with R = 0.4 using scaled p(T) spectra of the jet constituents is studied. The measurements are compared to model calculations from event generators (PYTHIA, PHOJET, HERWIG). The measured radial density distributions and distributions are well described by the PYTHIA model (tune Perugia-2011). The fragmentation distributions are better described by HERWIG.Peer reviewe

    Performance of the ALICE experiment at the CERN LHC

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    ALICE is the heavy-ion experiment at the CERN Large Hadron Collider. The experiment continuously took data during the first physics campaign of the machine from fall 2009 until early 2013, using proton and lead-ion beams. In this paper we describe the running environment and the data handling procedures, and discuss the performance of the ALICE detectors and analysis methods for various physics observables

    Centrality Dependence Of The Pseudorapidity Density Distribution For Charged Particles In Pb-pb Collisions At √snn=2.76tev

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    7264/Mai61062

    Measurement of jet suppression in central Pb-Pb collisions at root s(NN)=2.76 TeV

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    The transverse momentum(p(T)) spectrum and nuclear modification factor (R-AA) of reconstructed jets in 0-10% and 10-30% central Pb-Pb collisions at root s(NN) = 2.76 TeV were measured. Jets were reconstructed using the anti-k(T) jet algorithm with a resolution parameter of R = 0.2 from charged and neutral particles, utilizing the ALICE tracking detectors and Electromagnetic Calorimeter (EMCal). The jet p(T) spectra are reported in the pseudorapidity interval of \eta(jet)\ 5 GeV/c to suppress jets constructed from the combinatorial background in Pb-Pb collisions. The leading charged particle requirement applied to jet spectra both in pp and Pb-Pb collisions had a negligible effect on the R-AA. The nuclear modification factor R-AA was found to be 0.28 +/- 0.04 in 0-10% and 0.35 +/- 0.04 in 10-30% collisions, independent of p(T), jet within the uncertainties of the measurement. The observed suppression is in fair agreement with expectations from two model calculations with different approaches to jet quenching. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V.Peer reviewe
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