Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe

Pseudorapidity and transverse-momentum distributions of charged particles in proton-proton collisions at root s=13 TeV

The pseudorapidity (eta) and transverse-momentum (p(T)) distributions of charged particles produced in proton-proton collisions are measured at the centre-of-mass energy root s = 13 TeV. The pseudorapidity distribution in vertical bar eta vertical bar <1.8 is reported for inelastic events and for events with at least one charged particle in vertical bar eta vertical bar <1. The pseudorapidity density of charged particles produced in the pseudorapidity region vertical bar eta vertical bar <0.5 is 5.31 +/- 0.18 and 6.46 +/- 0.19 for the two event classes, respectively. The transverse-momentum distribution of charged particles is measured in the range 0.15 <p(T) <20 GeV/c and vertical bar eta vertical bar <0.8 for events with at least one charged particle in vertical bar eta vertical bar <1. The evolution of the transverse momentum spectra of charged particles is also investigated as a function of event multiplicity. The results are compared with calculations from PYTHIA and EPOS Monte Carlo generators. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at root s(NN)=2.76TeV

The elliptic flow, v(2), of muons from heavy-flavour hadron decays at forward rapidity (2.5 <y <4) is measured in Pb-Pb collisions at root s(NN)= 2.76TeVwith the ALICE detector at the LHC. The scalar product, two- and four-particle Q cumulants and Lee-Yang zeros methods are used. The dependence of the v(2) of muons from heavy-flavour hadron decays on the collision centrality, in the range 0-40%, and on transverse momentum, p(T), is studied in the interval 3 <p(T)<10 GeV/c. A positive v(2) is observed with the scalar product and two-particle Q cumulants in semi-central collisions (10-20% and 20-40% centrality classes) for the p(T) interval from 3 to about 5GeV/c with a significance larger than 3 sigma, based on the combination of statistical and systematic uncertainties. The v(2) magnitude tends to decrease towards more central collisions and with increasing pT. It becomes compatible with zero in the interval 6 <p(T)<10 GeV/c. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V.Peer reviewe

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

The study of J?Y production with the ALICE experimente using the electromagnetic calorimeter

Neste trabalho, obteve-se a medida da seção de choque de produção de J/ com pT > 5 GeV/c em rapidez central (|y| 5 GeV/c. Os valores obtidos da seção de choque diferencial (d2/dpT dy) foram: 0.42 ± 0,11(est.) ± 0,13(sis.) b GeV/c para pT entre 5 e 7 GeV/c, 0,18 ± 0,03(est.) ± 0,04(sis.) b GeV/c para pT entre 7 e 9 GeV/c, 0,041 ± 0,008(est.) ± 0,008(sis.) b GeV/c para pT entre 9 e 11 GeV/c e 0,014 ± 0,003(est.) ± 0,005(sis.) b GeV/c para pT entre 11 e 14 GeV/c. Esses valores são compatíveis com cálculos da QCD não relativística (NRQCD) e com o modelo de evaporação de cor (CEM). Além disso, na região de intersecção de pT , os resultados são compatíveis com aqueles obtidos pelo experimento ALICE (para baixo momento) e com as medidas obtidas pelo experimento ATLAS (para pT > 6 GeV/c). Além disso, por intermédio da reconstrução do vértice de decaimento do J/, foi possível estimar a fração de J/s que vieram de decaimentos de mésons B (fB). Os valores obtidos foram: fB = 0,267 ± 0,114 (hpT i = 7,15 GeV/c), fB = 0,338 ± 0,116 (hpT i = 10,7 GeV/c), fB = 0,271 ± 0,087 (hpT i = 8,5 GeV/c), que são compatíveis, dentro das incertezas experimentais, com valores obtidos no experimento ATLAS. Um último estudo realizado foi a viabilidade de medida de J/ com valor de pT > 6 GeV/c em colisões Pb-Pb. Para isso, valendo-se do sistema de trigger de L1 do EMCal, foram obtidos 93 ± 16 J/ reconstruídos em uma região de centralidade de 20-60%.This work presents the measurement of the J/ production with pT > 5 GeV/c at midrapidity (|y| 6 GeV/c). This work also shows the measurement of the fraction of non-prompt J/ (fB). The results were: fB = 0,267 ± 0,114 (hpT i = 7,15 GeV/c), fB = 0,338 ± 0,116 (hpT i = 10,7 GeV/c), fB = 0,271 ± 0,087 (hpT i = 8,5 GeV/c), which are compatible with ATLAS results. The last study made in this work was the feasility of the measurement of J/ in Pb-Pb collisions for pT > 6 GeV/c, using the EMCal L1 Gamma trigger. Considering events from the centrality region 20-60%, 93 ± 16 J/s were reconstructed

Estudo da produção de J/ψJ/\psi o experimento ALICE utilizando o calorímetro eletromagnético

This work presents the measurement of the J/ production with pT > 5 GeV/c at midrapidity (|y| 6 GeV/c). This work also shows the measurement of the fraction of non-prompt J/ (fB). The results were: fB = 0,267 ± 0,114 (hpT i = 7,15 GeV/c), fB = 0,338 ± 0,116 (hpT i = 10,7 GeV/c), fB = 0,271 ± 0,087 (hpT i = 8,5 GeV/c), which are compatible with ATLAS results. The last study made in this work was the feasility of the measurement of J/ in Pb-Pb collisions for pT > 6 GeV/c, using the EMCal L1 Gamma trigger. Considering events from the centrality region 20-60%, 93 ± 16 J/s were reconstructed.Neste trabalho, obteve-se a medida da seção de choque de produção de J/ com pT > 5 GeV/c em rapidez central (|y| 5 GeV/c. Os valores obtidos da seção de choque diferencial (d2/dpT dy) foram: 0.42 ± 0,11(est.) ± 0,13(sis.) b GeV/c para pT entre 5 e 7 GeV/c, 0,18 ± 0,03(est.) ± 0,04(sis.) b GeV/c para pT entre 7 e 9 GeV/c, 0,041 ± 0,008(est.) ± 0,008(sis.) b GeV/c para pT entre 9 e 11 GeV/c e 0,014 ± 0,003(est.) ± 0,005(sis.) b GeV/c para pT entre 11 e 14 GeV/c. Esses valores são compatíveis com cálculos da QCD não relativística (NRQCD) e com o modelo de evaporação de cor (CEM). Além disso, na região de intersecção de pT , os resultados são compatíveis com aqueles obtidos pelo experimento ALICE (para baixo momento) e com as medidas obtidas pelo experimento ATLAS (para pT > 6 GeV/c). Além disso, por intermédio da reconstrução do vértice de decaimento do J/, foi possível estimar a fração de J/s que vieram de decaimentos de mésons B (fB). Os valores obtidos foram: fB = 0,267 ± 0,114 (hpT i = 7,15 GeV/c), fB = 0,338 ± 0,116 (hpT i = 10,7 GeV/c), fB = 0,271 ± 0,087 (hpT i = 8,5 GeV/c), que são compatíveis, dentro das incertezas experimentais, com valores obtidos no experimento ATLAS. Um último estudo realizado foi a viabilidade de medida de J/ com valor de pT > 6 GeV/c em colisões Pb-Pb. Para isso, valendo-se do sistema de trigger de L1 do EMCal, foram obtidos 93 ± 16 J/ reconstruídos em uma região de centralidade de 20-60%

燒津鰹漁業に於ける船仲組織(上) - 本邦漁業に特異なる勞働組織の一例 -

We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at √sNN = 2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged onedimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with _dNch/dη_1/3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller √sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider