Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The yield of charged particles associated with high-$p_{\rm T}$ trigger particles ($8 < p_{\rm T} < 15$ GeV/$c$) is measured with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jet-like correlation peaks in azimuthal di-hadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta $p_{\rm T}> 3$ GeV/$c$ on the away-side drops to about 60% of that observed in pp collisions, while on the near-side a moderate enhancement of 20-30% is found.Comment: 15 pages, 2 captioned figures, 1 table, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/350

Characterization of zinc-releasing three-dimensional bioactive glass scaffolds and their effect on human adipose stem cell proliferation and osteogenic differentiation

While the addition of zinc ions to bioactive ceramics has been shown to enhance the proliferation and osteogenic differentiation of osteoblast-like cells, contradictory results have been found. Therefore, the effect of zinc-releasing ceramics on cell proliferation and differentiation into osteogenic lineages requires further clarification. The aim of this study was to evaluate the effects of zinc addition on the degradation profile of three-dimensional bioactive glass scaffold, and on the proliferation and osteogenesis of human adipose stem cells (hASCs) in these scaffolds. Bioactive glass scaffolds containing Na2O, K2O, MgO, CaO, B2O3, TiO2, P2O5 and SiO2 were prepared. The degradation was evaluated by weight loss measurement, scanning electron microscopy and elemental analysis. The degradation profile of bioactive glass was shown to slow down with the addition of zinc. Qualitative live/dead staining showed that zinc addition to bioactive glass inhibits cell spreading and proliferati

Centrality Dependence of the Charged-Particle Multiplicity Density at Midrapidity in Pb-Pb Collisions at root s(NN)=2.76 TeV

The centrality dependence of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at root s(NN) = 2: 76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor of 2 from peripheral (70%-80%) to central (0%-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions

Hyperon production at the CERN SPS: results from the NA57 experiment

New results on strange baryon and antibaryon production in Pb\u2013Pb collisions at 40 and 160 GeV per nucleon are presented. In particular, we have increased significantly the statistics of the \u39e 12 and samples at 160 GeV per nucleon. The dependence of particle yields and spectra on collision centrality and energy of interaction is analysed

Harmonic decomposition of two particle angular correlations in Pb\u2013Pb collisions at 1asNN = 2.76 TeV.

Angular correlations between unidentified charged trigger (t) and associated (a) particles are measured by the ALICE experiment in Pb\u2013Pb collisions at 1asNN = 2.76 TeV for transverse momenta 0.25 p(aT) . The shapes of the pair correlation distributions are studied in a variety of collision centrality classes between 0 and 50% of the total hadronic cross section for particles in the pseudorapidity interval |\u3b7| 0.8, and are referred to as \u201clong-range correlations\u201d. Fourier components Vn 61 cos(n\u3c6) are extracted from the long-range azimuthal correlation functions. If particle pairs are correlated to one another through their individual correlation to a common symmetry plane, then the pair anisotropy Vn(p(tT) , p(aT) ) is fully described in terms of single-particle anisotropies vn(pT) as Vn(p(tT), p(aT)) = vn(p(tT)vn(paT). This expectation is tested for 1 64 n 64 5 by applying a global fit of all Vn(p(tT), p(aT) to obtain the best values vn{GF}(pT ). It is found that for 2 64 n 64 5, the fit agrees well with data up to p(aT) ~ 3\u20134 GeV/c, with a trend of increasing deviation as p(tT) and p(aT) are increased or as collisions become more peripheral. This suggests that no pair correlation harmonic can be described over the full 0.25 < pT < 15 GeV/c range using a single vn(pT) curve; such a description is however approximately possible for 2 64 n 64 5 when p(aT) <4 GeV/c. For the n = 1 harmonic, however, a single v1(pT) curve is not obtained even within the reduced range p(aT) <4 GeV/c

Light vector meson production in pp collisions at sqrt(s)= 7 TeV.

The ALICE experiment has measured low-mass dimuon production in pp collisions at root s = 7 TeV in the dimuon rapidity region 2.5 < y < 4. The observed dimuon mass spectrum is described as a superposition of resonance decays (eta, rho, omega, eta', phi) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for omega and phi are sigma(omega)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 5.28 +/- 0.54(stat) +/- 0.49(syst) mb and sigma(phi)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 0.940 +/- 0.084(stat) +/- 0.076(syst) mb. The differential cross sections d(2)sigma/dy dp(t) are extracted as a function of p(t) for omega and phi. The ratio between the rho and omega cross section is obtained. Results for the phi are compared with other measurements at the same energy and with predictions by models

J/psi polarization in pp collisions at sqrt(s)=7 TeV

See paper for full list of authors - 3 figures, 1 table, submitted to Phys. Rev. LettInternational audienceThe ALICE Collaboration has studied J/psi production in pp collisions at sqrt(s)=7 TeV at the LHC through its muon pair decay. The polar and azimuthal angle distributions of the decay muons were measured, and results on the J/psi polarization parameters lambda_theta and lambda_phi were obtained. The study was performed in the kinematic region 2.