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Measurement of the azimuthal anisotropy of charged particles produced in $\sqrt{s_{_\text {NN}}}$ = 5.02 TeV Pb+Pb collisions with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Eur.Phys.J. C78 (2018) 997, 2018.
Inspire Record 1686834 DOI 10.17182/hepdata.84427

Measurements of the azimuthal anisotropy in lead–lead collisions at $\sqrt{s_{_\text {NN}}}$ = 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  $<p_{\mathrm{T}}<$  60 GeV, the pseudorapidity, $|\eta |<$  2.5, and the collision centrality 0–80%. Results from different methods are compared and discussed in the context of previous and recent measurements in Pb+Pb collisions at $\sqrt{s_{_\text {NN}}}$ = 2.76  $\mathrm{TeV}$ and 5.02  $\mathrm{TeV}$ . In particular, the shape of the $p_{\mathrm{T}}$ dependence of elliptic or triangular flow harmonics is observed to be very similar at different centralities after scaling the $v_{n}$ and $p_{\mathrm{T}}$ values by constant factors over the centrality interval 0–60% and the $p_{\mathrm{T}}$ range 0.5  $< p_{\mathrm{T}}<$  5 GeV.

83 data tables

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%

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J/$\psi$ elliptic flow in Pb-Pb collisions at $\mathbf{\sqrt{s_{\rm NN}}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adolfsson, Jonatan ; et al.
No Journal Information, 2017.
Inspire Record 1623907 DOI 10.17182/hepdata.80235

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.

4 data tables

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.

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D-meson azimuthal anisotropy in mid-central Pb-Pb collisions at $\mathbf{\sqrt{s_{\rm NN}}=5.02}$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adolfsson, Jonatan ; et al.
No Journal Information, 2017.
Inspire Record 1608612 DOI 10.17182/hepdata.78255

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.

0 data tables

Flow dominance and factorization of transverse momentum correlations in Pb-Pb collisions at the LHC

The ALICE collaboration Adam, Jaroslav ; Adamova, Dagmar ; Aggarwal, Madan Mohan ; et al.
Phys.Rev.Lett. 118 (2017) 162302, 2017.
Inspire Record 1512772 DOI 10.17182/hepdata.78231

We present the first measurement of the two-particle transverse momentum differential correlation function, P2≡⟨ΔpTΔpT⟩/⟨pT⟩2, in Pb-Pb collisions at sNN=2.76  TeV. Results for P2 are reported as a function of the relative pseudorapidity (Δη) and azimuthal angle (Δφ) between two particles for different collision centralities. The Δϕ dependence is found to be largely independent of Δη for |Δη|≥0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around Δφ=π (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 P2, studied as a function of the collision centrality, show that correlations at |Δη|≥0.9 can be well reproduced by a flow ansatz based on the notion that measured transverse momentum correlations are strictly determined by the collective motion of the system.

0 data tables

Version 2
Anisotropic flow of charged particles in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV

The ALICE collaboration Adam, Jaroslav ; Adamova, Dagmar ; Aggarwal, Madan Mohan ; et al.
Phys.Rev.Lett. 116 (2016) 132302, 2016.
Inspire Record 1419244 DOI 10.17182/hepdata.72886

We report the first results of elliptic (v2), triangular (v3), and quadrangular (v4) flow of charged particles in Pb-Pb collisions at a center-of-mass energy per nucleon pair of sNN=5.02  TeV with the ALICE detector at the CERN Large Hadron Collider. The measurements are performed in the central pseudorapidity region |η|<0.8 and for the transverse momentum range 0.2<pT<5  GeV/c. The anisotropic flow is measured using two-particle correlations with a pseudorapidity gap greater than one unit and with the multiparticle cumulant method. Compared to results from Pb-Pb collisions at sNN=2.76  TeV, the anisotropic flow coefficients v2, v3, and v4 are found to increase by (3.0±0.6)%, (4.3±1.4)%, and (10.2±3.8)%, respectively, in the centrality range 0%–50%. This increase can be attributed mostly to an increase of the average transverse momentum between the two energies. The measurements are found to be compatible with hydrodynamic model calculations. This comparison provides a unique opportunity to test the validity of the hydrodynamic picture and the power to further discriminate between various possibilities for the temperature dependence of shear viscosity to entropy density ratio of the produced matter in heavy-ion collisions at the highest energies.

0 data tables

Pseudorapidity dependence of the anisotropic flow of charged particles in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV

The ALICE collaboration Adam, Jaroslav ; Adamova, Dagmar ; Aggarwal, Madan Mohan ; et al.
Phys.Lett. B762 (2016) 376-388, 2016.
Inspire Record 1456145 DOI 10.17182/hepdata.73940

We present measurements of the elliptic ($\mathrm{v}_2$), triangular ($\mathrm{v}_3$) and quadrangular ($\mathrm{v}_4$) anisotropic azimuthal flow over a wide range of pseudorapidities ($-3.5< \eta < 5$). The measurements are performed with Pb-Pb collisions at $\sqrt{s_{\text{NN}}} = 2.76$ TeV using the ALICE detector at the Large Hadron Collider (LHC). The flow harmonics are obtained using two- and four-particle correlations from nine different centrality intervals covering central to peripheral collisions. We find that the shape of $\mathrm{v}_n(\eta)$ is largely independent of centrality for the flow harmonics $n=2-4$, however the higher harmonics fall off more steeply with increasing $|\eta|$. We assess the validity of extended longitudinal scaling of $\mathrm{v}_2$ by comparing to lower energy measurements, and find that the higher harmonic flow coefficients are proportional to the charged particle densities at larger pseudorapidities. Finally, we compare our measurements to both hydrodynamical and transport models, and find they both have challenges when it comes to describing our data.

9 data tables

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Measurement of the pseudorapidity and transverse momentum dependence of the elliptic flow of charged particles in lead-lead collisions at $\sqrt{s_{NN}}=2.76$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Phys.Lett. B707 (2012) 330-348, 2012.
Inspire Record 925720 DOI 10.17182/hepdata.58021

This paper describes the measurement of elliptic flow of charged particles in lead-lead collisions at sqrt(s_NN) = 2.76 TeV using the ATLAS detector at the Large Hadron Collider (LHC). The results are based on an integrated luminosity of approximately 7 ub^-1. Elliptic flow is measured over a wide region in pseudorapidity, |eta| < 2.5, and over a broad range in transverse momentum, 0.5 < p_T < 20 GeV. The elliptic flow parameter v_2 is obtained by correlating individual tracks with the event plane measured using energy deposited in the forward calorimeters. As a function of transverse momentum, v_2(p_T) reaches a maximum at p_T of about 3 GeV, then decreases and becomes weakly dependent on p_T above 7 - 8 GeV. Over the measured pseudorapidity region, v_2 is found to be approximately independent of |eta| for all collision centralities and particle transverse momenta, something not observed in lower energy collisions. The results are discussed in the context of previous measurements at lower collision energies, as well as recent results from the LHC.

64 data tables

v2(pT) for centrality interval 0-10% and |eta| <1.

v2(pT) for centrality interval 10-20% and |eta| <1.

v2(pT) for centrality interval 20-30% and |eta| <1.

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Long-range pseudorapidity dihadron correlations in $d$+Au collisions at $\sqrt{s_{\rm NN}}=200$ GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Lett. B747 (2015) 265-271, 2015.
Inspire Record 1346551 DOI 10.17182/hepdata.72303

Dihadron angular correlations in $d$+Au collisions at $\sqrt{s_{\rm NN}}=200$ GeV are reported as a function of the measured zero-degree calorimeter neutral energy and the forward charged hadron multiplicity in the Au-beam direction. A finite correlated yield is observed at large relative pseudorapidity ($\Delta\eta$) on the near side (i.e. relative azimuth $\Delta\phi\sim0$). This correlated yield as a function of $\Delta\eta$ appears to scale with the dominant, primarily jet-related, away-side ($\Delta\phi\sim\pi$) yield. The Fourier coefficients of the $\Delta\phi$ correlation, $V_{n}=\langle\cos n\Delta\phi\rangle$, have a strong $\Delta\eta$ dependence. In addition, it is found that $V_{1}$ is approximately inversely proportional to the mid-rapidity event multiplicity, while $V_{2}$ is independent of it with similar magnitude in the forward ($d$-going) and backward (Au-going) directions.

23 data tables

Correlated dihadron yield, per radian per unit of pseudorapidity, as a function of $\Delta\phi$ for 1.2 < $|\Delta\eta|$ < 1.8 in d+Au collisions, for low ZDC-Au activity data. Both the trigger and associated particles have 1 < $p_T$ < 3 GeV/c.

Correlated dihadron yield, per radian per unit of pseudorapidity, as a function of $\Delta\phi$ for 1.2 < $|\Delta\eta|$ < 1.8 in d+Au collisions, for high ZDC-Au activity data. Both the trigger and associated particles have 1 < $p_T$ < 3 GeV/c.

Correlated dihadron yield, per radian per unit of pseudorapidity, as a function of $\Delta\phi$ for -4.5 < $\Delta\eta$ < -2 in d+Au collisions, for low ZDC-Au activity data. Both the trigger and associated particles have 1 < $p_T$ < 3 GeV/c.

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Observation of charge asymmetry dependence of pion elliptic flow and the possible chiral magnetic wave in heavy-ion collisions

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 114 (2015) 252302, 2015.
Inspire Record 1358666 DOI 10.17182/hepdata.72237

We present measurements of π- and π+ elliptic flow, v2, at midrapidity in Au+Au collisions at sNN=200, 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV, as a function of event-by-event charge asymmetry, Ach, based on data from the STAR experiment at RHIC. We find that π- (π+) elliptic flow linearly increases (decreases) with charge asymmetry for most centrality bins at sNN=27  GeV and higher. At sNN=200  GeV, the slope of the difference of v2 between π- and π+ as a function of Ach exhibits a centrality dependence, which is qualitatively similar to calculations that incorporate a chiral magnetic wave effect. Similar centrality dependence is also observed at lower energies.

10 data tables

The distribution of observed charge asymmetry from STAR data.

Pion $v_2${2} as a function of observed charge asymmetry.

$v_2$ difference between $\pi^-$ and $\pi^+$ as a function of charge asymmetry with the tracking efficiency correction, for 30-40% central Au+Au collisions at 200 GeV. The errors are statistical only.

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Azimuthal anisotropy in U$+$U and Au$+$Au collisions at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 115 (2015) 222301, 2015.
Inspire Record 1373553 DOI 10.17182/hepdata.71502

Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at sNN=193  GeV and Au+Au collisions at sNN=200  GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. We also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

0 data tables

Centrality and transverse momentum dependence of elliptic flow of multistrange hadrons and $\phi$ meson in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 116 (2016) 062301, 2016.
Inspire Record 1383879 DOI 10.17182/hepdata.71571

We present high precision measurements of elliptic flow near midrapidity ($|y|<1.0$) for multi-strange hadrons and $\phi$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $\sqrt{s_{NN}}=$ 200 GeV. We observe that the transverse momentum dependence of $\phi$ and $\Omega$ $v_{2}$ is similar to that of $\pi$ and $p$, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30$\%$ and 30-80$\%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $\phi$ and proton $v_{2}$ at low transverse momentum in the 0-30$\%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_{2}$.

23 data tables

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Centrality dependence of identified particle elliptic flow in relativistic heavy ion collisions at $\sqrt{s_{NN}}$=7.7–62.4 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev. C93 (2016) 014907, 2016.
Inspire Record 1395151 DOI 10.17182/hepdata.71527

Elliptic flow (v2) values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at sNN=7.7–62.4 GeV are presented for three centrality classes. The centrality dependence and the data at sNN=14.5 GeV are new. Except at the lowest beam energies, we observe a similar relative v2 baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger v2 for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with a multiphase transport (AMPT) model and fit with a blast wave model.

392 data tables

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Measurement of flow harmonics with multi-particle cumulants in Pb+Pb collisions at $\sqrt{s_{\mathrm {NN}}}=2.76$  TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Eur.Phys.J. C74 (2014) 3157, 2014.
Inspire Record 1311487 DOI 10.17182/hepdata.65771

ATLAS measurements of the azimuthal anisotropy in lead–lead collisions at $\sqrt{s_{\mathrm {NN}}}=2.76$  TeV are shown using a dataset of approximately 7  $\upmu $ b$^{-1}$ collected at the LHC in 2010. The measurements are performed for charged particles with transverse momenta $0.5<p_{\mathrm {T}}<20$  GeV and in the pseudorapidity range $|\eta |<2.5$ . The anisotropy is characterized by the Fourier coefficients, $\mathrm {v}_n$ , of the charged-particle azimuthal angle distribution for $n = 2$ –4. The Fourier coefficients are evaluated using multi-particle cumulants calculated with the generating function method. Results on the transverse momentum, pseudorapidity and centrality dependence of the $\mathrm {v}_n$ coefficients are presented. The elliptic flow, $\mathrm {v}_2$ , is obtained from the two-, four-, six- and eight-particle cumulants while higher-order coefficients, $\mathrm {v}_3$ and $\mathrm {v}_4$ , are determined with two- and four-particle cumulants. Flow harmonics $\mathrm {v}_n$ measured with four-particle cumulants are significantly reduced compared to the measurement involving two-particle cumulants. A comparison to $\mathrm {v}_n$ measurements obtained using different analysis methods and previously reported by the LHC experiments is also shown. Results of measurements of flow fluctuations evaluated with multi-particle cumulants are shown as a function of transverse momentum and the collision centrality. Models of the initial spatial geometry and its fluctuations fail to describe the flow fluctuations measurements.

220 data tables

The second flow harmonic measured with the two-particle cumulants as a function of transverse momentum in centrality bin 0-2%.

The second flow harmonic measured with the two-particle cumulants as a function of transverse momentum in centrality bin 2-5%.

The second flow harmonic measured with the two-particle cumulants as a function of transverse momentum in centrality bin 5-10%.