The inclusive J/$\psi$ elliptic ($v_2$) and triangular ($v_3$) flow coefficients measured at forward rapidity (2.5 $<y<$ 4) and the $v_2$ measured at midrapidity ($|y|<$ 0.9) in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV using the ALICE detector at the LHC are reported. The entire Pb-Pb data sample collected during Run 2 is employed, amounting to an integrated luminosity of 750 $\mu$b$^{-1}$ at forward rapidity and 93 $\mu$b$^{-1}$ at midrapidity. The results are obtained using the scalar product method and are reported as a function of transverse momentum $p_{\rm T}$ and collision centrality. At midrapidity, the J/$\psi$ $v_2$ is in agreement with the forward rapidity measurement. The centrality averaged results indicate a positive J/$\psi$ $v_3$ with a significance of more than 5$\sigma$ at forward rapidity in the $p_{\rm T}$ range $2<p_{\rm T}<5$ GeV/$c$. The forward rapidity $v_2$, $v_3$, and $v_3$/$v_2$ results at low and intermediate $p_{\rm T}$ ($p_{\rm T} \lesssim 8$ GeV/$c$) exhibit a mass hierarchy when compared to pions and D mesons, while converging into a species-independent curve at higher $p_{\rm T}$. At low and intermediate $p_{\rm T}$, the results could be interpreted in terms of a later thermalization of charm quarks compared to light quarks, while at high $p_{\rm T}$, path-length dependent effects seem to dominate. The J/$\psi$ $v_2$ measurements are further compared to a microscopic transport model calculation. Using a simplified extension of the quark scaling approach involving both light and charm quark flow components, it is shown that the D-meson $v_{\rm n}$ measurements can be described based on those for charged pions and J/$\psi$ flow.
Inclusive J/$\psi$ $v_2$ as a function of $p_{T}$ in the centrality interval 0$-$10.0 %
Inclusive J/$\psi$ $v_2$ as a function of $p_{T}$ in the centrality interval 10$-$30 %
Inclusive J/$\psi$ $v_2$ as a function of $p_{T}$ in the centrality interval 30$-$50 %
The elliptic and triangular flow coefficients $v_2$ and $v_3$ of prompt D$^{0}$, D$^{+}$, and D$^{*+}$ mesons were measured at midrapidity ($|y|<0.8$) in Pb-Pb collisions at the centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}} = 5.02$ TeV with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays in the transverse momentum interval $1< p_{\rm T}<36$ GeV/$c$ in central (0-10%) and semi-central (30-50%) collisions. Compared to pions, protons, and J/$\psi$ mesons, the average D-meson $v_{n}$ harmonics are compatible within uncertainties with a mass hierarchy for $p_{\rm T} \lesssim 3$ GeV/$c$, and are similar to those of charged pions for higher $p_{\rm T}$. The coupling of the charm quark to the light quarks in the underlying medium is further investigated with the application of the event-shape engineering (ESE) technique to the D-meson $v_2$ and $p_{\rm T}$-differential yields. The D-meson $v_2$ is correlated with average bulk elliptic flow in both central and semi-central collisions. Within the current precision, the ratios of per-event D-meson yields in the ESE-selected and unbiased samples are found to be compatible with unity. All the measurements are found to be reasonably well described by theoretical calculations including the effects of charm-quark transport and the recombination of charm quarks with light quarks in a hydrodynamically expanding medium.
Average $v_2${SP} vs. $p_\mathrm{T}$ of prompt D$^0$, D$^+$, and D$^{*+}$ mesons in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV in the centrality class 0-10% in the rapidity interval $|y|<0.8$. The first (sys,data) error is the systematic uncertainty from all the other sources except for the B feed-down. The second (sys,FD) error is the systematic uncertainty from the B feed-down contribution.
Average $v_2${SP} vs. $p_\mathrm{T}$ of prompt D$^0$, D$^+$, and D$^{*+}$ mesons in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV in the centrality class 30-50% in the rapidity interval $|y|<0.8$. The first (sys,data) error is the systematic uncertainty from all the other sources except for the B feed-down. The second (sys,FD) error is the systematic uncertainty from the B feed-down contribution.
Average $v_3${SP} vs. $p_\mathrm{T}$ of prompt D$^0$, D$^+$, and D$^{*+}$ mesons in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV in the centrality class 0-10% in the rapidity interval $|y|<0.8$. The first (sys,data) error is the systematic uncertainty from all the other sources except for the B feed-down. The second (sys,FD) error is the systematic uncertainty from the B feed-down contribution.
We report systematic measurements of bulk properties of the system created in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 14.5 GeV recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC).The transverse momentum spectra of $\pi^{\pm}$, $K^{\pm}$ and $p(\bar{p})$ are studied at mid-rapidity ($|y| < 0.1$) for nine centrality intervals. The centrality, transverse momentum ($p_T$),and pseudorapidity ($\eta$) dependence of inclusive charged particle elliptic flow ($v_2$), and rapidity-odd charged particles directed flow ($v_{1}$) results near mid-rapidity are also presented. These measurements are compared with the published results from Au+Au collisions at other energies, and from Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. The results at $\sqrt{s_{\mathrm{NN}}}$ = 14.5 GeV show similar behavior as established at other energies and fit well in the energy dependence trend. These results are important as the 14.5 GeV energy fills the gap in $\mu_B$, which is of the order of 100 MeV,between $\sqrt{s_{\mathrm{NN}}}$ =11.5 and 19.6 GeV. Comparisons of the data with UrQMD and AMPT models show poor agreement in general.
The $p_{T}$ spectra of proton measured at midrapidity (|y|<0.1) in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.5 GeV. Spectra are plotted for nine centrality classes, with some spectra multiplied by a scale factor to improve clarity, as indicated in the legend
The $p_{T}$ spectra of antiproton measured at midrapidity (|y|<0.1) in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.5 GeV. Spectra are plotted for nine centrality classes, with some spectra multiplied by a scale factor to improve clarity, as indicatedin the legend
The $p_{T}$ spectra of $\pi^{+}$ measured at midrapidity (|y|<0.1) in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.5 GeV. Spectra are plotted for nine centrality classes, with some spectra multiplied by a scale factor to improve clarity, as indicatedin the legend
The production yield of prompt D mesons and their elliptic flow coefficient $v_2$ were measured with the Event-Shape Engineering (ESE) technique applied to mid-central (10-30% and 30-50% centrality classes) Pb-Pb collisions at the centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} =5.02$ TeV, with the ALICE detector at the LHC. The ESE technique allows the classification of events, belonging to the same centrality, according to the azimuthal anisotropy of soft particle production in the collision. The reported measurements give the opportunity to investigate the dynamics of charm quarks in the Quark-Gluon Plasma and provide information on their participation in the collective expansion of the medium. D mesons were reconstructed via their hadronic decays at mid-rapidity, $|\eta|<0.8$, in the transverse momentum interval $1<p_{\rm T}<24$ GeV/$c$. The $v_2$ coefficient is found to be sensitive to the event-shape selection confirming a correlation between the D-meson azimuthal anisotropy and the collective expansion of the bulk matter, while the per-event D-meson yields do not show any significant modification within the current uncertainties.
v_{2}{EP} vs. p_{T} of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8 The first (sys) error is the systematic uncertainty from the other sources The second (sys) error is the systematic uncertainty from the B feed-down contribution.
v_{2}{EP} vs. p_{T} of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8 The first (sys) error is the systematic uncertainty from the other sources The second (sys) error is the systematic uncertainty from the B feed-down contribution.
v_{2}{EP} vs. p_{T} of prompt D*+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8 The first (sys) error is the systematic uncertainty from the other sources The second (sys) error is the systematic uncertainty from the B feed-down contribution.
Measurements of the azimuthal anisotropy in lead-lead collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV are presented using a data sample corresponding to 0.49 $\mathrm{nb}^{-1}$ integrated luminosity collected by the ATLAS experiment at the LHC in 2015. The recorded minimum-bias sample is enhanced by triggers for "ultra-central" collisions, providing an opportunity to perform detailed study of flow harmonics in the regime where the initial state is dominated by fluctuations. The anisotropy of the charged-particle azimuthal angle distributions is characterized by the Fourier coefficients, $v_{2}-v_{7}$, which are measured using the two-particle correlation, scalar-product and event-plane methods. The goal of the paper is to provide measurements of the differential as well as integrated flow harmonics $v_{n}$ over wide ranges of the transverse momentum, 0.5 $
The V2 harmonic measured with the scalar product method as a funtion of transverse momentum in centrality bin 0-0.1%
The V2 harmonic measured with the scalar product method as a funtion of transverse momentum in centrality bin 0-1%
The V2 harmonic measured with the scalar product method as a funtion of transverse momentum in centrality bin 0-5%
We report a precise measurement of the J/$\psi$ elliptic flow in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV with the ALICE detector at the LHC. The J/$\psi$ mesons are reconstructed at mid-rapidity ($|y| < 0.9$) in the dielectron decay channel and at forward rapidity ($2.5<y<4.0$) in the dimuon channel, both down to zero transverse momentum. At forward rapidity, the elliptic flow $v_2$ of the J/$\psi$ is studied as a function of transverse momentum and centrality. A positive $v_2$ is observed in the transverse momentum range $2 < p_{\rm T} < 8$ GeV/$c$ in the three centrality classes studied and confirms with higher statistics our earlier results at $\sqrt{s_{\rm NN}} = 2.76$ TeV in semi-central collisions. At mid-rapidity, the J/$\psi$ $v_2$ is investigated as a function of transverse momentum in semi-central collisions and found to be in agreement with the measurements at forward rapidity. These results are compared to transport model calculations. The comparison supports the idea that at low $p_{\rm T}$ the elliptic flow of the J/$\psi$ originates from the thermalization of charm quarks in the deconfined medium, but suggests that additional mechanisms might be missing in the models.
Transverse momentum dependence of inclusive J/$\psi$ $v_2$ at $\sqrt{s_{\rm NN}}=5.02$ TeV for the 20-40% centrality class (forward rapidity). The first uncertainty (stat) is statistical, the second (sys,uncorrel) is the uncorrelated systematic, while the third one (sys,correl) is a $p_{\rm T}$-correlated systematic uncertainty.
Transverse momentum dependence of inclusive J/$\psi$ $v_2$ at $\sqrt{s_{\rm NN}}=5.02$ TeV for the 20-40% centrality class (mid-rapidity). The first uncertainty (stat) is statistical, the second (sys,uncorrel) is the uncorrelated systematic, while the third one (sys,correl) is a $p_{\rm T}$-correlated systematic uncertainty.
Transverse momentum dependence of inclusive J/$\psi$ $v_2$ at $\sqrt{s_{\rm NN}}=5.02$ TeV for the 5-20% centrality class (forward rapidity). The first uncertainty (stat) is statistical, the second (sys,uncorrel) is the uncorrelated systematic, while the third one (sys,correl) is a $p_{\rm T}$-correlated systematic uncertainty.
The azimuthal anisotropy coefficient $v_2$ of prompt D$^0$, D$^+$, D$^{*+}$ and D$_s^+$ mesons was measured in mid-central (30-50% centrality class) Pb-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV, with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays at mid-rapidity, $|y|<0.8$, in the transverse momentum interval $1<p_{\rm T}<24$ GeV/$c$. The measured D-meson $v_2$ has similar values as that of charged pions. The D$_s^+$ $v_2$, measured for the first time, is found to be compatible with that of non-strange D mesons. The measurements are compared with theoretical calculations of charm-quark transport in a hydrodynamically expanding medium and have the potential to constrain medium parameters.
$v_2$ vs. $p_{\rm T}$ of $D^0$ mesons in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$=5.02 TeV in the centrality class 30-50% in the rapidity interval |$y$|<0.8. The second (sys) error is the systematic uncertainty from the B feed-down contribution. The first (sys) error is the systematic uncertainty from the other sources.
$v_2$ vs. $p_{\rm T}$ of $D^+$ mesons in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$=5.02 TeV in the centrality class 30-50% in the rapidity interval |$y$|<0.8. The second (sys) error is the systematic uncertainty from the B feed-down contribution. The first (sys) error is the systematic uncertainty from the other sources.
$v_2$ vs. $p_{\rm T}$ of $D^{*+}$ mesons in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$=5.02 TeV in the centrality class 30-50% in the rapidity interval |$y$|<0.8. The second (sys) error is the systematic uncertainty from the B feed-down contribution. The first (sys) error is the systematic uncertainty from the other sources.
We present the first measurement of the two-particle transverse momentum differential correlation function, $P_2\equiv\langle \Delta p_{\rm T} \Delta p_{\rm T} \rangle /\langle p_{\rm T} \rangle^2$, in Pb-Pb collisions at $\sqrt{s_{_{\rm NN}}} =$ 2.76 TeV. Results for $P_2$ are reported as a function of relative pseudorapidity ($\Delta \eta$) and azimuthal angle ($\Delta \varphi$) between two particles for different collision centralities. The $\Delta \phi$ dependence is found to be largely independent of $\Delta \eta$ for $|\Delta \eta| \geq$ 0.9. In 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around $\Delta \varphi = \pi$ (i.e., on the away side), which is not observed in number correlations in the same centrality range, and thus provides an indication of the dominance of triangular flow in this collision centrality. Fourier decompositions of $P_2$, studied as a function of collision centrality, show that correlations at $|\Delta \eta| \geq$ 0.9 can be well reproduced by a flow ansatz based on the notion that measured momentum correlations are strictly determined by the collective motion of the system.
Projection of $P_{2}$ along $\Delta\varphi$ in 0-5% centrality in the range $|\Delta \eta| \geq$ 0.9
$v_{2}$ coefficients measured from $P_2$ for particle pairs in the range $0.2 \leq |\Delta\eta| \leq 0.9$.
$v_{2}$ coefficients measured from $P_2$ for particle pairs in the range $0.9 \leq |\Delta\eta| \leq 1.9$.
Correlations between the elliptic or triangular flow coefficients $v_m$ ($m$=2 or 3) and other flow harmonics $v_n$ ($n$=2 to 5) are measured using $\sqrt{s_{NN}}=2.76$ TeV Pb+Pb collision data collected in 2010 by the ATLAS experiment at the LHC, corresponding to an integrated lumonisity of 7 $\mu$b$^{-1}$. The $v_m$-$v_n$ correlations are measured in midrapidity as a function of centrality, and, for events within the same centrality interval, as a function of event ellipticity or triangularity defined in a forward rapidity region. For events within the same centrality interval, $v_3$ is found to be anticorrelated with $v_2$ and this anticorrelation is consistent with similar anticorrelations between the corresponding eccentricities $\epsilon_2$ and $\epsilon_3$. On the other hand, it is observed that $v_4$ increases strongly with $v_2$, and $v_5$ increases strongly with both $v_2$ and $v_3$. The trend and strength of the $v_m$-$v_n$ correlations for $n$=4 and 5 are found to disagree with $\epsilon_m$-$\epsilon_n$ correlations predicted by initial-geometry models. Instead, these correlations are found to be consistent with the combined effects of a linear contribution to $v_n$ and a nonlinear term that is a function of $v_2^2$ or of $v_2v_3$, as predicted by hydrodynamic models. A simple two-component fit is used to separate these two contributions. The extracted linear and nonlinear contributions to $v_4$ and $v_5$ are found to be consistent with previously measured event-plane correlations.
$v_{2}$ data for various $q_2$ bins, Centrality 0-5%.
$v_{3}$ data for various $q_2$ bins, Centrality 0-5%.
$v_{4}$ data for various $q_2$ bins, Centrality 0-5%.
Measurements of two-particle correlation functions and the first five azimuthal harmonics, $v_1$ to $v_5$, are presented, using 28 $\mathrm{nb}^{-1}$ of $p$+Pb collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV measured with the ATLAS detector at the LHC. Significant long-range "ridge-like" correlations are observed for pairs with small relative azimuthal angle ($|\Delta\phi|<\pi/3$) and back-to-back pairs ($|\Delta\phi| > 2\pi/3$) over the transverse momentum range $0.4 < p_{\rm T} < 12$ GeV and in different intervals of event activity. The event activity is defined by either the number of reconstructed tracks or the total transverse energy on the Pb-fragmentation side. The azimuthal structure of such long-range correlations is Fourier decomposed to obtain the harmonics $v_n$ as a function of $p_{\rm T}$ and event activity. The extracted $v_n$ values for $n=2$ to 5 decrease with $n$. The $v_2$ and $v_3$ values are found to be positive in the measured $p_{\rm T}$ range. The $v_1$ is also measured as a function of $p_{\rm T}$ and is observed to change sign around $p_{\rm T}\approx 1.5$-2.0 GeV and then increase to about 0.1 for $p_{\rm T}>4$ GeV. The $v_2(p_{\rm T})$, $v_3(p_{\rm T})$ and $v_4(p_{\rm T})$ are compared to the $v_n$ coefficients in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}} =2.76$ TeV with similar event multiplicities. Reasonable agreement is observed after accounting for the difference in the average $p_{\rm T}$ of particles produced in the two collision systems.
The distributions of $N_{ch}^{rec}$ for MB and MB+HMT after applying an event-by-event weight, errors are statistical.
The distributions of $E_{T}^{Pb}$ [GeV] for MB and MB+HMT after applying an event-by-event weight, errors are statistical.
Per-trigger yield in 2D, $Y$($\Delta\phi$,$\Delta\eta$), for events with $E_{T}^{Pb} <$ 10 GeV and $N_{ch}^{rec} \geq$ 200 and recoil-subtracted per-trigger yield, $Y^{sub}$($\Delta\phi$,$\Delta\eta$) for events with $N_{ch}^{rec} \geq$ 200. Errors are statistical.
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