Nonlinear response coeffcients of higher-order vn anisotropy harmonics for charged particles, as a function of transverse momentum (pT) and collision centrality, are measured in PbPb collisions at ...√sNN = 2.76 and 5.02 TeV. The nonlinear response coefficients are obtained using vn harmonics measured with respect to their own plane and the mixed harmonics. Using a fine splitting between v
2
{4} and v
2
{6} cumulants, the centrality dependence of the elliptic flow skewness is measured at 5.02 TeV PbPb collisions. The CMS also measured the v
2
and v
3
anisotropy harmonics of charged particles and prompt D
0
mesons at |y| ≤ 1 as a function of pT and centrality in PbPb data at √sNN = 5.02 TeV collected with the CMS detector. Prompt D
0
mesons, formed from the c quarks produced via initial hard scatterings, are separated up to a high extent from nonprompt D
0
mesons emerged from decays of b hadrons. The results indicate that the charm quarks interact strongly with the QGP medium. Comparisons between theoretical models and data provide new constraints on the initial-state conditions and the interaction between charm quarks and the QGP medium.
The v3 coefficient, obtained using the PbAu data from the CERES detector at the top SPS energy of √sNN = 17.3 GeV, is presented. The v2 is measured over a pT range up to 100 GeV/c in PbPb collisions ...collected with the CMS detector. The v2{2} of charged and strange particles emitted in pp collisions shows a mass ordering effect. The v2{4} and v2{6} are comparable to the v2{2}, and thus supports the collective nature of the long-range correlations in high-multiplicity pp collisions at 13 TeV. Principle Component Analysis (PCA) of two-particle harmonics (VnΔ) is studied in PbPb and high-multiplicity pPb collisions at the LHC. The factorization breaking of the VnΔ can be attributed to the effect of initial-state fluctuations. Using a PCA, the VnΔ are characterized through the leading and sub-leading modes. The leading modes are essentially equivalent to the vn{2}. The sub-leading modes represent the largest sources of factorization breaking.
Differential elliptic flow of v sub(2)(pT) for pi super(-), (ProQuest: Formulae and/or non-USASCII text omitted), p and Lambda is measured at center-of-mass energy of radicalsNN=17.3 GeV near the ...mid-rapidity region in rather central PbAu collisions collected by the CERES/NA45 experiment at CERN. The proton v sub(2)(pT) is extracted from pi super(+) sample and particle ratios measured by NA49 experiment adapted to CERES conditions. The proton v sub(2)(pT) data show a downward swing towards low pT with excursions into negative v sub(2) values which was not observed earlier. The results are compared with corresponding measurements performed at NA49 and STAR experiments as well as with theoretical predictions from ideal relativistic hydrodynamics. The obtained results for baryons are below hydrodynamic predictions even at the kinetic freeze-out temperature of T sub(functionof)=160 MeV which needs introducing of a viscous hydrodynamics at the late hadronic phase.
A Principle Component Analysis (PCA) of two-particle azimuthal correlations as a function of transverse momentum (pT) is presented in PbPb collisions at 2.76 TeV and high-multiplicity pPb collisions ...at 5.02 TeV. The data were recorded using the CMS detector at the LHC. It was shown that factorization breaking of two-particle azimuthal correlations can be attributed to the effect of initial-state fluctuations. Using a PCA approach, Fourier coefficients of observed two-particle azimuthal correlations as a function of both particles' pT are characterized into leading and sub-leading mode terms. The leading modes are essentially equivalent to anisotropy harmonics (vn) previously extracted from two-particle correlation methods as a function of pT. The sub-leading modes represent the largest sources of factorization breaking. In the context of hydrodynamic models, they are a direct consequence of initial-state fluctuations. The results are presented over a wide range of centrality and event multiplicity. The results are connected to the measurement of pT-dependent flow factorization breaking.
The LHC results on the sub-leading flow modes in PbPb collisions at 2.76 TeV, related to initial-state fluctuations, are analyzed and interpreted within the HYDJET++ model. Using the newly introduced ...Principal Component Analysis (PCA) method applied to two-particle azimuthal correlations extracted from the model calculations, the leading and the sub-leading flow modes are studied as a function of the transverse momentum (pT ) over a wide centrality range. The leading modes of the elliptic (v
(1)
2
) and triangular (v
3
(1)
3) flow calculated within the HYDJET++ model reproduce rather well the v
2
{2} and v
3
{2} coeffcients experimentally measured using the two-particle correlations. Within the pT ≤3 GeV/c range where hydrodynamics dominates, the sub-leading flow effects are greatest at the highest pT of around 3 GeV/c. The sub-leading elliptic flow mode (v
2
(2)
), which corresponds to n=2 harmonic, has a small non-zero value and slowly increases from central to peripheral collisions, while the sub-leading triangular flow mode (v
3
(2)
), which corresponds to n =3 harmonic, is even smaller and does not depend on centrality. For n =2, the relative magnitude of the effect measured with respect to the leading flow mode shows a shallow minimum for semi-central collisions and increases for very central and for peripheral collisions. For n =3 case, there is no centrality dependence. The subleading flow mode results obtained from the HYDJET++ model are in a rather good agreement with the experimental measurements of the CMS Collaboration.
The growth of La2NiO4+δ at the interface between La2O3 and NiO has been studied from 950 to 1450°C in argon, air and oxygen. The thickness, microstructure and composition of the formed La2NiO4+δ ...layers have been characterized by means of SEM, EDX, EBSD, EPMA and XRD. The growth rate follows parabolic kinetics. It has been concluded from the position of Pt markers that La2NiO4+δ grows predominantly by solid state diffusion of Ni2+, and the experimental results were accordingly fitted with Wagner's expressions for self-diffusion. Above 1100°C the diffusion coefficients follow Arrhenius-type temperature dependencies, with activation energies 243 ± 21 and 218 ± 21 kJ/mol evaluated for the conditions at the La2O3/La2NiO4+δ and NiO/La2NiO4+δ interfaces, respectively. Below 1100°C the diffusivity falls more steeply with decreasing temperature, and possible explanations are discussed. Compared to cation diffusion in perovskite-type oxides, Ni2+ diffusivity in La2NiO4+δ is in higher range.
The elliptic flow (v2) event-by-event fluctuations in PbPb collisions at 5.02 TeV are analyzed within the HYDJET++ model. Using the multiparticle, so-called Q-cumulant method, v2{2}, v2{4}, v2{6}, ...and v2{8} are calculated and used to study their ratios and to construct skewness (γexp1) as a measure of the asymmetry of the elliptic flow distribution. Additionally, in order to check if there is a hydrodynamics nature in the elliptic collectivity generated by the HYDJET++ model, the ratio of v2{6}−v2{8} and v2{4}−v2{6} distributions is calculated. The analysis is performed as a function of the collision centrality. In order to check the HYDJET++ model responses, the results of this analysis are compared to the corresponding experimental measurements from the ALICE, ATLAS, and CMS experiments. A rather good qualitative agreement is found.
The CMS collaboration measured second-order single-particle anisotropy, ν2, using 2-, 4-, 6- and 8-particle correlations as well as the Lee-Yang Zero method in pPb and PbPb collisions. This result ...shows that the correlations found in the small and highly asymmetric pPb collision system are long-range and have a many-particle origin. Deeper insight into the nature of these correlations is achieved by studying the factorization breaking effect which appears trough a pT-dependent event plane angle, caused by the initial-state fluctuations. The effect is largest for the most-central PbPb collisions (up to 20%), while it is on the level of few percent for peripheral PbPb and high-multiplicity pPb events. Hydrodynamics models which include a pT-dependent event plane angle semi-quantitatively describe the data and suggest that the effect is mainly determined by the initial-state conditions.
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