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  1. Evolution of the differential transverse momentum correlation function with centrality in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV
    Erschienen: 2011
    Verlag:  HAL CCSD ; Elsevier

    See paper for full list of authors - 7 pages, 4 figures, STAR paper published in Phys. Lett. B ; We present first measurements of the evolution of the differential transverse momentum correlation function, {\it C}, with collision centrality in Au+Au... mehr

     

    See paper for full list of authors - 7 pages, 4 figures, STAR paper published in Phys. Lett. B ; We present first measurements of the evolution of the differential transverse momentum correlation function, {\it C}, with collision centrality in Au+Au interactions at $\sqrt{s_{NN}} = 200$ GeV. {\it C} exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of {\it C} with increasing centrality to estimate the ratio of the shear viscosity to entropy density, $\eta/s$, of the matter formed in central Au+Au interactions. We obtain an upper limit estimate of $\eta/s$ that suggests that the produced medium has a small viscosity per unit entropy.

     

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    Übergeordneter Titel: ISSN: 0370-2693 ; Physics Letters B ; http://hal.in2p3.fr/in2p3-00697047 ; Physics Letters B, Elsevier, 2011, 704, pp.467-473. ⟨10.1016/j.physletb.2011.09.075⟩
    Schlagworte: [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  2. Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at sqrt(s)=0.9, 2.76 and 7 TeV

    See paper for full list of authors - 21 pages, 11 figures ; Measurements of the sphericity of primary charged particles in minimum bias proton--proton collisions at sqrt(s)=0.9, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The... mehr

     

    See paper for full list of authors - 21 pages, 11 figures ; Measurements of the sphericity of primary charged particles in minimum bias proton--proton collisions at sqrt(s)=0.9, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is linearized to be collinear safe and is measured in the plane perpendicular to the beam direction using primary charged tracks with $p_{\rm T}\geq0.5$ GeV/c in $|\eta|\leq0.8$. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity ($N_{\rm ch}$) is reported for events with different $p_{\rm T}$ scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low $N_{\rm ch}$, whereas the event generators show the opposite tendency. The combined study of the sphericity and the mean $p_{\rm T}$ with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.

     

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    Übergeordneter Titel: ISSN: 1434-6044 ; EISSN: 1434-6052 ; European Physical Journal C: Particles and Fields ; http://hal.in2p3.fr/in2p3-00699404 ; European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2012, 72, pp.2124. ⟨10.1140/epjc/s10052-012-2124-9⟩
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]
  3. Measurement of prompt and non-prompt J/psi production cross sections at mid-rapidity in pp collisions at sqrt(s) = 7 TeV

    see paper for full list of authors ; The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at {\surd}s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L_int =... mehr

     

    see paper for full list of authors ; The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at {\surd}s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L_int = 5.6nb-1. The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum pt > 1.3 GeV/c and rapidity |y| < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the Psi(2S) and Csi_c resonances, is sigma_prompt-J/psi(pt > 1.3 GeV/c, |y| < 0.9) = 7.2 +- 0.7(stat.) +- 1.0(syst.)+1.3-1.2 (syst.pol.) mb. The pt-differential cross section for prompt J/psi has also been measured. The cross section for the production of b-hadrons decaying to J/psi with transverse momentum greater than 1.3 GeV/c in the rapidity range |y| < 0.9 is sigma_{J/psi<-h_B} = 1.26 +- 0.33 (stat.) +0.23-0.28 (syst.) mb. The results are compared to QCD model predictions. The shape of the pt and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the bb pair total cross section and dsigma/dy at midrapidity.

     

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    Übergeordneter Titel: ISSN: 1126-6708 ; EISSN: 1029-8479 ; Journal of High Energy Physics ; http://hal.in2p3.fr/in2p3-00702009 ; Journal of High Energy Physics, Springer, 2012, 2012, pp.065. &#x27E8;10.1007/JHEP11(2012)065&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]
  4. Measurement of charm production at central rapidity in proton-proton collisions at sqrt(s) = 2.76 TeV

    See paper for full list of authors ; The pt-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D0, D+, and D*+ in the rapidity range |y|<0.5, and for transverse momentum 1< pt <12 GeV/c, were measured in... mehr

     

    See paper for full list of authors ; The pt-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D0, D+, and D*+ in the rapidity range |y|<0.5, and for transverse momentum 1< pt 12 GeV/c, were measured in proton-proton collisions at sqrt(s) = 2.76 TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D0 -> K pi, D+ -> K pi pi, D*+ -> D0 pi, and their charge conjugates, and was performed on a L_{int} = 1.35 nb^{-1} event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at sqrt(s) = 2.76 TeV and at 7 TeV was evaluated by extrapolating to the full phase space the pt-differential production cross sections at sqrt(s) = 2.76 TeV and our previous measurements at sqrt(s) = 7 TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cubar D mesons produced in a vector state was also determined.

     

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    Übergeordneter Titel: ISSN: 1126-6708 ; EISSN: 1029-8479 ; Journal of High Energy Physics ; http://hal.in2p3.fr/in2p3-00705656 ; Journal of High Energy Physics, Springer, 2012, 7, pp.191. &#x27E8;10.1007/JHEP07(2012)191&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  5. K0s-K0s correlations in pp collisions at sqrt{s}=7 TeV from the LHC ALICE experiment

    See paper for full list of authors - 10 pages + author list, 7 figures, to be submitted to Physics Letters B ; Identical neutral kaon pair correlations are measured in sqrt{s}=7 TeV pp collisions in the ALICE experiment. One-dimensional K0s-K0s... mehr

     

    See paper for full list of authors - 10 pages + author list, 7 figures, to be submitted to Physics Letters B ; Identical neutral kaon pair correlations are measured in sqrt{s}=7 TeV pp collisions in the ALICE experiment. One-dimensional K0s-K0s correlation functions in terms of the invariant momentum difference of kaon pairs are formed in two multiplicity and two transverse momentum ranges. The femtoscopic parameters for the radius and correlation strength of the kaon source are extracted. The fit includes quantum statistics and final-state interactions of the a0/f0 resonance. K0s-K0s correlations show an increase in radius for increasing multiplicity and a slight decrease in radius for increasing transverse mass, mT, as seen in pion-pion correlations in the pp system and in heavy-ion collisions. Transverse mass scaling is observed between the K0s-K0s and pion-pion radii. Also, the first observation is made of the decay of the f2'(1525) meson into the K0s-K0s channel in pp collisions.

     

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    Übergeordneter Titel: ISSN: 0370-2693 ; Physics Letters B ; https://hal.in2p3.fr/in2p3-00707149 ; Physics Letters B, Elsevier, 2012, 717, pp.151-161. &#x27E8;10.1016/j.physletb.2012.09.013&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  6. Measurement of inelastic, single- and double-diffraction cross sections in proton--proton collisions at the LHC with ALICE

    see paper for full list of authors, 27 pages, 12 figures, submitted to Eur. Phys. J. C ; Measurements of cross sections of inelastic and diffractive processes in proton--proton collisions at LHC energies were carried out with the ALICE detector. The... mehr

     

    see paper for full list of authors, 27 pages, 12 figures, submitted to Eur. Phys. J. C ; Measurements of cross sections of inelastic and diffractive processes in proton--proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass $M_X < 200$ GeV/$c^2$) $\sigma_{\rm SD}/\sigma_{\rm INEL} = 0.21 \pm 0.03, 0.20^{+0.07}_{-0.08}$, and $0.20^{+0.04}_{-0.07}$, respectively at centre-of-mass energies $\sqrt{s} = 0.9, 2.76$, and 7 TeV; for double diffraction (for a pseudorapidity gap $\Delta\eta > 3$) $\sigma_{\rm DD}/\sigma_{\rm INEL} = 0.11 \pm 0.03, 0.12 \pm 0.05$, and $0.12^{+0.05}_{-0.04}$, respectively at $\sqrt{s} = 0.9, 2.76$, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: $\sigma_{\rm INEL} = 62.8^{+2.4}_{-4.0} (model) \pm 1.2 (lumi)$ mb at $\sqrt{s} =$ 2.76 TeV and $73.2^{+2.0}_{-4.6} (model) \pm 2.6 (lumi)$ mb at $\sqrt{s}$ = 7 TeV. The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton--antiproton and proton--proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

     

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    Übergeordneter Titel: ISSN: 1434-6044 ; EISSN: 1434-6052 ; European Physical Journal C: Particles and Fields ; http://hal.in2p3.fr/in2p3-00725471 ; European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2013, 73, pp.2456. &#x27E8;10.1140/epjc/s10052-013-2456-0&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]
  7. New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products

    10 pages, 2 figures ; In this paper, we study the impact of the inclusion of the recently measured beta decay properties of the $^{102;104;105;106;107}$Tc, $^{105}$Mo, and $^{101}$Nb nuclei in an updated calculation of the antineutrino energy spectra... mehr

     

    10 pages, 2 figures ; In this paper, we study the impact of the inclusion of the recently measured beta decay properties of the $^{102;104;105;106;107}$Tc, $^{105}$Mo, and $^{101}$Nb nuclei in an updated calculation of the antineutrino energy spectra of the four fissible isotopes $^{235, 238}$U, and $^{239,241}$Pu. These actinides are the main contributors to the fission processes in Pressurized Water Reactors. The beta feeding probabilities of the above-mentioned Tc, Mo and Nb isotopes have been found to play a major role in the $\gamma$ component of the decay heat of $^{239}$Pu, solving a large part of the $\gamma$ discrepancy in the 4 to 3000\,s range. They have been measured using the Total Absorption Technique (TAS), avoiding the Pandemonium effect. The calculations are performed using the information available nowadays in the nuclear databases, summing all the contributions of the beta decay branches of the fission products. Our results provide a new prediction of the antineutrino energy spectra of $^{235}$U, $^{239,241}$Pu and in particular of $^{238}$U for which no measurement has been published yet. We conclude that new TAS measurements are mandatory to improve the reliability of the predicted spectra.

     

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    Übergeordneter Titel: ISSN: 0031-9007 ; EISSN: 1079-7114 ; Physical Review Letters ; http://hal.in2p3.fr/in2p3-00734002 ; Physical Review Letters, American Physical Society, 2012, 109, pp.202504. &#x27E8;10.1103/PhysRevLett.109.202504&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  8. Long-range angular correlations on the near and away side in p-Pb collisions at sqrt(sNN) = 5.02 TeV

    See paper for full list of authors - 22 pages, 5 figures, author list from page 16; submitted to PLB ; Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon... mehr

     

    See paper for full list of authors - 22 pages, 5 figures, author list from page 16; submitted to PLB ; Angular correlations between 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 for transverse momentum ranges within 0.5 < pT,assoc < pT,trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and pT bins, and the widths show no significant evolution with event multiplicity or pT. These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge.

     

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    Übergeordneter Titel: ISSN: 0370-2693 ; Physics Letters B ; http://hal.in2p3.fr/in2p3-00763590 ; Physics Letters B, Elsevier, 2013, 719, pp.29-41. &#x27E8;10.1016/j.physletb.2013.01.012&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  9. Charged kaon femtoscopic correlations in pp collisions at $\sqrt{s}=7$ TeV

    See paper for full list of authors - 16 pages, 4 figures ; Correlations of two charged identical kaons (Kch Kch) are measured in pp collisions at sqrt{s}=7 TeV by the ALICE experiment at the Large Hadron Collider (LHC). One-dimensional Kch Kch... mehr

     

    See paper for full list of authors - 16 pages, 4 figures ; Correlations of two charged identical kaons (Kch Kch) are measured in pp collisions at sqrt{s}=7 TeV by the ALICE experiment at the Large Hadron Collider (LHC). One-dimensional Kch Kch correlation functions are constructed in three multiplicity and four transverse momentum ranges. The Kch Kch femtoscopic source parameters R and lambda are extracted. The Kch Kch correlations show a slight increase of femtoscopic radii with increasing multiplicity and a slight decrease of radii with increasing transverse momentum. These trends are similar to the ones observed for pi pi and Ks0 Ks0 correlations in pp and heavy-ion collisions. However, the observed one dimensional correlation radii for charged kaons are larger at high multiplicities than those for pions in contrast to what was observed in heavy-ion collisions at RHIC.

     

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    Übergeordneter Titel: ISSN: 1550-7998 ; EISSN: 1550-2368 ; Physical Review D ; http://hal.in2p3.fr/in2p3-00769524 ; Physical Review D, American Physical Society, 2013, 87, pp.052016. &#x27E8;10.1103/PhysRevD.87.052016&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  10. Charge correlations using the balance function in Pb-Pb collisions at sqrt{s_{NN}} = 2.76 TeV

    See paper for full list of authors - 37 pages, 7 figures, one column, author list until page 12, submitted to Physics Letters B ; In high-energy heavy-ion collisions, the correlations between the emitted particles can be used as a probe to gain... mehr

     

    See paper for full list of authors - 37 pages, 7 figures, one column, author list until page 12, submitted to Physics Letters B ; In high-energy heavy-ion collisions, the correlations between the emitted particles can be used as a probe to gain insight into the charge creation mechanisms. In this article, we report the first results of such studies using the electric charge balance function in the relative pseudorapidity \Delta\eta and azimuthal angle \Delta\phi in Pb-Pb collisions at sqrt{s_{NN}} = 2.76 TeV with the ALICE detector at the Large Hadron Collider. The width of the balance function decreases with growing centrality (i.e. for more central collisions) in both projections. This centrality dependence is not reproduced by HIJING, while AMPT, a model which incorporates strings and parton rescattering, exhibits qualitative agreement with the measured correlations in \Delta\phi but fails to describe the correlations in \Delta\eta. A thermal blast wave model incorporating local charge conservation and tuned to describe the p_T spectra and v_2 measurements reported by ALICE, is used to fit the centrality dependence of the width of the balance function and to extract the average separation of balancing charges at freeze-out. The comparison of our results with measurements at lower energies reveals an ordering with sqrt{s_{NN}}: the balance functions become narrower with increasing energy for all centralities. This is consistent with the effect of larger radial flow at the LHC energies but also with the late stage creation scenario of balancing charges. However, the relative decrease of the balance function widths in \Delta\eta and \Delta\phi with centrality from the highest SPS to the LHC energy exhibits only small differences. This observation cannot be interpreted solely within the framework where the majority of the charge is produced at a later stage in the evolution of the heavy-ion collision.

     

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    Übergeordneter Titel: ISSN: 0370-2693 ; Physics Letters B ; http://hal.in2p3.fr/in2p3-00777176 ; Physics Letters B, Elsevier, 2013, 723, pp.267-279. &#x27E8;10.1016/j.physletb.2013.05.039&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]; [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th]
  11. Centrality determination of Pb-Pb collisions at sqrt(sNN) = 2.76 TeV with ALICE

    37 pages, 16 figures, authors from page 31 ; see paper for full list of authors ; This publication describes the methods used to measure the centrality of inelastic Pb-Pb collisions at a center-of-mass energy of 2.76 TeV per colliding nucleon pair... mehr

     

    37 pages, 16 figures, authors from page 31 ; see paper for full list of authors ; This publication describes the methods used to measure the centrality of inelastic Pb-Pb collisions at a center-of-mass energy of 2.76 TeV per colliding nucleon pair with ALICE. The centrality is a key parameter in the study of the properties of QCD matter at extreme temperature and energy density, because it is directly related to the initial overlap region of the colliding nuclei. Geometrical properties of the collision, such as the number of participating nucleons and number of binary nucleon-nucleon collisions, are deduced from a Glauber model with a sharp impact parameter selection, and shown to be consistent with those extracted from the data. The centrality determination provides a tool to compare ALICE measurements with those of other experiments and with theoretical calculations.

     

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    Übergeordneter Titel: ISSN: 2469-9985 ; EISSN: 2469-9993 ; Physical Review C ; http://hal.in2p3.fr/in2p3-00778545 ; Physical Review C, American Physical Society, 2013, 88, pp.044909. &#x27E8;10.1103/PhysRevC.88.044909&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  12. J/Psi Elliptic Flow in Pb-Pb Collisions at sqrt(sNN) = 2.76 TeV

    16 pages, 4 figures, 1 Table, authors from page 11 to 13 ; see paper for full list of authors ; We report on the first measurement of inclusive J/Psi elliptic flow, v2, in heavy-ion collisions at the LHC. The measurement is performed with the ALICE... mehr

     

    16 pages, 4 figures, 1 Table, authors from page 11 to 13 ; see paper for full list of authors ; We report on the first measurement of inclusive J/Psi elliptic flow, v2, in heavy-ion collisions at the LHC. The measurement is performed with the ALICE detector in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV in the rapidity range 2.5 < y < 4.0. The dependence of the J/Psi v2 on the collision centrality and on the J/Psi transverse momentum is studied in the range 0 <= pT < 10 GeV/c. For semi-central Pb-Pb collisions at sqrt(sNN) = 2.76 TeV, an indication of non-zero v2 is observed with a maximum value of v2 = 0.116+/-0.046(stat.)+/-0.029(syst.) for J/Psi in the transverse momentum range 2 <= pT < 4 GeV/c. The elliptic flow measurement complements the previously reported ALICE results on the inclusive J/Psi nuclear modification factor and favors the scenario of a significant fraction of J/Psi production from charm quarks in a deconfined partonic phase.

     

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    Übergeordneter Titel: ISSN: 0031-9007 ; EISSN: 1079-7114 ; Physical Review Letters ; https://hal.in2p3.fr/in2p3-00804625 ; Physical Review Letters, American Physical Society, 2013, 111, pp.162301. &#x27E8;10.1103/PhysRevLett.111.162301&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  13. Centrality dependence of the pseudorapidity density distribution for charged particles in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV

    21 pages, 9 captioned figures, 2 tables, authors from page 16 to page 18 ; see paper for full list of authors ; We present the first wide-range measurement of the charged-particle pseudorapidity density distribution, for different centralities (the... mehr

     

    21 pages, 9 captioned figures, 2 tables, authors from page 16 to page 18 ; see paper for full list of authors ; We present the first wide-range measurement of the charged-particle pseudorapidity density distribution, for different centralities (the 0-5%, 5-10%, 10-20%, and 20-30% most central events) in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV at the LHC. The measurement is performed using the full coverage of the ALICE detectors, -5.0 < eta < 5.5, and employing a special analysis technique based on collisions arising from LHC 'satellite' bunches. We present the pseudorapidity density as a function of the number of participating nucleons as well as an extrapolation to the total number of produced charged particles Nch = 17165 +/- 772 for the 0-5% most central collisions). From the measured dNch/deta distribution we derive the rapidity density distribution, dNch/dy, under simple assumptions. The rapidity density distribution is found to be significantly wider than the predictions of the Landau model, which reproduce data well at RHIC energies. We assess the validity of longitudinal scaling by comparing to lower energy results from RHIC. Finally the mechanisms of the underlying particle production are discussed based on a comparison with various theoretical models.

     

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    Übergeordneter Titel: ISSN: 0370-2693 ; Physics Letters B ; http://hal.in2p3.fr/in2p3-00806582 ; Physics Letters B, Elsevier, 2013, 726, pp.610-622. &#x27E8;10.1016/j.physletb.2013.09.022&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  14. Directed flow of charged particles at mid-rapidity relative to the spectator plane in Pb-Pb collisions at sqrt{s_NN}=2.76 TeV

    17 pages, 4 captioned figures, author from page 12 to 17 ; see paper for full list of authors ; The directed flow of charged particles at mid-rapidity is measured in Pb-Pb collisions at sqrt{s_NN}=2.76 TeV relative to the collision plane defined by... mehr

     

    17 pages, 4 captioned figures, author from page 12 to 17 ; see paper for full list of authors ; The directed flow of charged particles at mid-rapidity is measured in Pb-Pb collisions at sqrt{s_NN}=2.76 TeV relative to the collision plane defined by the spectator nucleons. Both, the rapidity odd (v_1^odd) and even (v_1^even) directed flow components are reported. The v_1^odd component has a negative slope as a function of pseudorapidity similar to that observed at the highest RHIC energy, but with about a three times smaller magnitude. The v^even component is found to be non-zero and independent of pseudorapidity. Both components show little dependence on the collision centrality and change sign at transverse momenta around 1.2-1.7 GeV/c for midcentral collisions. The shape of v_1^even as a function of transverse momentum and a vanishing transverse momentum shift along the spectator deflection for v_1^even are consistent with dipole-like initial density fluctuations in the overlap zone of the nuclei.

     

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    Übergeordneter Titel: ISSN: 0031-9007 ; EISSN: 1079-7114 ; Physical Review Letters ; https://hal.in2p3.fr/in2p3-00835541 ; Physical Review Letters, American Physical Society, 2013, 111, pp.232302. &#x27E8;10.1103/PhysRevLett.111.232302&#x27E9;
    Schlagworte: [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  15. Scaling properties at freeze-out in relativistic heavy ion collisions
    Erschienen: 2010
    Verlag:  HAL CCSD ; American Physical Society

    submitted to Phys.Rev.C, 13 pages, 14 figures ; see paper for full list of authors ; Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at... mehr

     

    submitted to Phys.Rev.C, 13 pages, 14 figures ; see paper for full list of authors ; Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at $\sqrt{s_{NN}}$=200 and 62.4 GeV. The data are studied with hydrodynamically-motivated Blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au+Au and $pp$ collisions, the dependence of freeze-out parameters on the system size is also explored. This multi-dimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance of the initial geometrical overlap of the colliding ions. The analysis of Cu+Cu collisions, which expands the system size dependence studies from Au+Au data with detailed measurements in the smaller system, shows that the bulk freeze-out properties of charged particles studied here scale with the total charged particle multiplicity at mid-rapidity, suggesting the relevance of initial state effects.

     

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    Übergeordneter Titel: ISSN: 2469-9985 ; EISSN: 2469-9993 ; Physical Review C ; http://hal.in2p3.fr/in2p3-00837652 ; Physical Review C, American Physical Society, 2010, 83, pp.034910. &#x27E8;10.1103/PhysRevC.83.034910&#x27E9;
    Schlagworte: [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  16. Energy Dependence of the Transverse Momentum Distributions of Charged Particles in pp Collisions Measured by ALICE

    18 pages, 5 captioned figures, 1 table, authors from page 13 to page 18 ; see paper for full list of authors ; Differential cross sections of charged particles in inelastic pp collisions as a function of p_T have been measured at sqrt(s) = 0.9, 2.76... mehr

     

    18 pages, 5 captioned figures, 1 table, authors from page 13 to page 18 ; see paper for full list of authors ; Differential cross sections of charged particles in inelastic pp collisions as a function of p_T have been measured at sqrt(s) = 0.9, 2.76 and 7 TeV at the LHC. The p_T spectra are compared to NLO-pQCD calculations. Though the differential cross section for an individual sqrt(s) cannot be described by NLO-pQCD, the relative increase of cross section with sqrt(s) is in agreement with NLO-pQCD. Based on these measurements and observations, procedures are discussed to construct pp reference spectra at sqrt(s) = 2.76 and 5.02 TeV up to p_T = 50 GeV/c as required for the calculation of the nuclear modification factor in nucleus-nucleus and proton-nucleus collisions.

     

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    Übergeordneter Titel: ISSN: 1434-6044 ; EISSN: 1434-6052 ; European Physical Journal C: Particles and Fields ; http://hal.in2p3.fr/in2p3-00841160 ; European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2013, 73, pp.2662. &#x27E8;10.1140/epjc/s10052-013-2662-9&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  17. Multiplicity dependence of the average transverse momentum in pp, p-Pb, and Pb-Pb collisions at the LHC

    18 pages, 4 captioned figures, 2 tables, author from page 13 to page 18 ; see paper for full list of authors ; The average transverse momentum versus the charged-particle multiplicity N_ch was measured in p-Pb collisions at a collision energy per... mehr

     

    18 pages, 4 captioned figures, 2 tables, author from page 13 to page 18 ; see paper for full list of authors ; The average transverse momentum versus the charged-particle multiplicity N_ch was measured in p-Pb collisions at a collision energy per nucleon-nucleon pair sqrt(s_NN) = 5.02 TeV and in pp collisions at collision energies of sqrt(s) = 0.9, 2.76, and 7 Tev in the kinematic range 0.15 < p_T < 10.0 Gev/c and |eta| < 0.3 with the ALICE apparatus at the LHC. These data are compared to results in Pb-Pb collisions at sqrt(s_NN) = 2.76 Tev at similar charged-particle multiplicities. In pp and p-Pb collisions, a strong increase of with N_ch is observed, which is much stronger than that measured in Pb-Pb collisions. For pp collisions, this could be attributed, within a model of hadronizing strings, to multiple-parton interactions and to a final-state color reconnection mechanism. The data in p-Pb and Pb-Pb collisions cannot be described by an incoherent superposition of nucleon-nucleon collisions and pose a challenge to most of the event generators.

     

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    Übergeordneter Titel: ISSN: 0370-2693 ; Physics Letters B ; https://hal.in2p3.fr/in2p3-00841162 ; Physics Letters B, Elsevier, 2013, 727, pp.371-380. &#x27E8;10.1016/j.physletb.2013.10.054&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  18. Long-range angular correlations of pi, K and p in p--Pb collisions at sqrt(s_NN) = 5.02 TeV

    See paper for full list of authors - 26 pages, 4 captioned figures, 2 tables, Author from page 20 to page 23 ; Angular correlations between unidentified charged trigger particles and various species of charged associated particles (unidentified... mehr

     

    See paper for full list of authors - 26 pages, 4 captioned figures, 2 tables, Author from page 20 to page 23 ; Angular correlations between unidentified charged trigger particles and various species of charged associated particles (unidentified particles, pions, kaons, protons and antiprotons) are measured by the ALICE detector in p-Pb collisions at a nucleon--nucleon centre-of-mass energy of 5.02 TeV in the transverse-momentum range 0.3 < p_T < 4 GeV/c. The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range |eta_lab|<0.8. Fourier coefficients are extracted from the long-range correlations projected onto the azimuthal angle difference and studied as a function of $\pt$ and in intervals of event multiplicity. In high-multiplicity events, the second-order coefficient for protons, v_2^p, is observed to be smaller than that for pions, v_2^pi, up to about p_T = 2 GeV/c. To reduce correlations due to jets, the per-trigger yield measured in low-multiplicity events is subtracted from that in high-multiplicity events. A two-ridge structure is obtained for all particle species. The Fourier decomposition of this structure shows that the second-order coefficients for pions and kaons are similar. The v_2^p is found to be smaller at low p_T and larger at higher p_T than v_2^pi, with a crossing occurring at about 2 GeV. This is qualitatively similar to the elliptic-flow pattern observed in heavy-ion collisions. A mass ordering effect at low transverse momenta is consistent with expectations from hydrodynamic model calculations assuming a collectively expanding system.

     

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    Übergeordneter Titel: ISSN: 0370-2693 ; Physics Letters B ; http://hal.in2p3.fr/in2p3-00843893 ; Physics Letters B, Elsevier, 2013, 726, pp.164-177. &#x27E8;10.1016/j.physletb.2013.08.024&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  19. J/psi production and nuclear effects in p-Pb collisions at sqrt(sNN)=5.02 TeV

    Comments: 20 pages, 6 captioned figures, 0 tables, authors from page 15 to page 17 ; see paper for full list of authors ; Inclusive J/psi production has been studied with the ALICE detector in p-Pb collisions at sqrt(sNN) = 5.02 TeV at the CERN LHC,... mehr

     

    Comments: 20 pages, 6 captioned figures, 0 tables, authors from page 15 to page 17 ; see paper for full list of authors ; Inclusive J/psi production has been studied with the ALICE detector in p-Pb collisions at sqrt(sNN) = 5.02 TeV at the CERN LHC, in the rapidity domains 2.03 < ycms < 3.53 and -4.46 < ycms < -2.96, down to zero transverse momentum. The J/psi measurement is performed in the Muon Spectrometer through the mu+ mu- decay mode. In this paper, the J/psi production cross section and the nuclear modification factor R(pPb) for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/psi yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. The ratio of the forward and backward yields is also shown differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results.

     

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    Übergeordneter Titel: ISSN: 1126-6708 ; EISSN: 1029-8479 ; Journal of High Energy Physics ; https://hal.in2p3.fr/in2p3-00856719 ; Journal of High Energy Physics, Springer, 2014, 2, pp.073. &#x27E8;10.1007/JHEP02(2014)073&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  20. Anomalous centrality evolution of two-particle angular correlations from Au-Au collisions at $\sqrt{s_{\rm NN}}$ = 62 and 200 GeV
    Erschienen: 2012
    Verlag:  HAL CCSD ; American Physical Society

    26 pages, 8 figures, 2 tables ; see paper for full list of authors ; We present two-dimensional (2D) two-particle angular correlations on relative pseudorapidity $\eta$ and azimuth $\phi$ for charged particles from Au-Au collisions at $\sqrt{s_{\rm... mehr

     

    26 pages, 8 figures, 2 tables ; see paper for full list of authors ; We present two-dimensional (2D) two-particle angular correlations on relative pseudorapidity $\eta$ and azimuth $\phi$ for charged particles from Au-Au collisions at $\sqrt{s_{\rm NN}} = 62$ and 200 GeV with transverse momentum $p_t \geq 0.15$ GeV/$c$, $|\eta| \leq 1$ and $2\pi$ azimuth. Observed correlations include a {same-side} (relative azimuth $< \pi/2$) 2D peak, a closely-related away-side azimuth dipole, and an azimuth quadrupole conventionally associated with elliptic flow. The same-side 2D peak and away-side dipole are explained by semihard parton scattering and fragmentation (minijets) in proton-proton and peripheral nucleus-nucleus collisions. Those structures follow N-N binary-collision scaling in Au-Au collisions until mid-centrality where a transition to a qualitatively different centrality trend occurs within a small centrality interval. Above the transition point the number of same-side and away-side correlated pairs increases rapidly {relative to} binary-collision scaling, the $\eta$ width of the same-side 2D peak also increases rapidly ($\eta$ elongation) and the $\phi$ width actually decreases significantly. Those centrality trends are more remarkable when contrasted with expectations of jet quenching in a dense medium. Observed centrality trends are compared to {\sc hijing} predictions and to the expected trends for semihard parton scattering and fragmentation in a thermalized opaque medium. We are unable to reconcile a semihard parton scattering and fragmentation origin for the observed correlation structure and centrality trends with heavy ion collision scenarios which invoke rapid parton thermalization. On the other hand, if the collision system is effectively opaque to few-GeV partons the observations reported here would be inconsistent with a minijet picture.

     

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    Übergeordneter Titel: ISSN: 2469-9985 ; EISSN: 2469-9993 ; Physical Review C ; http://hal.in2p3.fr/in2p3-00876853 ; Physical Review C, American Physical Society, 2012, 86, pp.064902. &#x27E8;10.1103/PhysRevC.86.064902&#x27E9;
    Schlagworte: [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
  21. Measurement of quarkonium production at forward rapidity in pp collisions at sqrt{s}= 7 TeV

    27 pages, 9 captioned figures, 6 tables, authors from page 22 to page 24 ; see paper for full list of authors ; The inclusive production cross sections at forward rapidity of J/psi, psi(2S), Upsilon(1S) and Upsilon(2S) are measured in pp collisions... mehr

     

    27 pages, 9 captioned figures, 6 tables, authors from page 22 to page 24 ; see paper for full list of authors ; The inclusive production cross sections at forward rapidity of J/psi, psi(2S), Upsilon(1S) and Upsilon(2S) are measured in pp collisions at sqrt{s} = 7 TeV with the ALICE detector at the LHC. The analysis is based in a data sample corresponding to an integrated luminosity of 1.35 pb^-1. Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the mu+mu- invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum pt and rapidity y, over the ranges 0 < pt < 20 GeV/c for J/psi, 0 < pt < 12 GeV/c for all other resonances and for 2.5 < y < 4. The measured cross sections integrated over pt and y, and assuming unpolarized quarkonia, are: sigma_{J/psi} = 6.69 +- 0.04 +- 0.63 microbarn, sigma_{psiprime} = 1.13 +- 0.07 +- 0.14 microbarn, sigma_{Upsilon(1S)} = 54.2 +- 5.0 +- 6.7 nb and sigma_{Upsilon(2S)} = 18.4 +- 3.7 +- 2.2 nb, where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models.

     

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    Übergeordneter Titel: ISSN: 1434-6044 ; EISSN: 1434-6052 ; European Physical Journal C: Particles and Fields ; http://hal.in2p3.fr/in2p3-00959806 ; European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2014, 74, pp.2974. &#x27E8;10.1140/epjc/s10052-014-2974-4&#x27E9;
    Schlagworte: [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]