Production of $\pi^0$, $\eta$, and $K_S$ mesons in U$+$U collisions at $\sqrt{s_{_{NN}}}=192$ GeV

The PHENIX collaboration Acharya, U. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.C 102 (2020) 064905, 2020.
Inspire Record 1798526 DOI 10.17182/hepdata.132824

The PHENIX experiment at the Relativistic Heavy Ion Collider measured $\pi^0$ and $\eta$ mesons at midrapidity in U$+$U collisions at $\sqrt{s_{_{NN}}}=192$ GeV in a wide transverse momentum range. Measurements were performed in the $\pi^0(\eta)\rightarrow\gamma\gamma$ decay modes. A strong suppression of $\pi^0$ and $\eta$ meson production at high transverse momentum was observed in central U$+$U collisions relative to binary scaled $p$$+$$p$ results. Yields of $\pi^0$ and $\eta$ mesons measured in U$+$U collisions show similar suppression pattern to the ones measured in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV for similar numbers of participant nucleons. The $\eta$/$\pi^0$ ratios do not show dependence on centrality or transverse momentum, and are consistent with previously measured values in hadron-hadron, hadron-nucleus, nucleus-nucleus, and $e^+e^-$ collisions.

41 data tables

$\pi^0$ spectra from figure 2a from minimum bias U+U collisions. Type A uncertainties are uncorrelated point-to-point. Type B uncertainties are correlated point-to-point. Type C uncertainties affect the scale of the data.

$\pi^0$ spectra from figure 2a from 0-20% U+U collisions. Type A uncertainties are uncorrelated point-to-point. Type B uncertainties are correlated point-to-point. Type C uncertainties affect the scale of the data.

$\pi^0$ spectra from figure 2a from 20-40% U+U collisions. Type A uncertainties are uncorrelated point-to-point. Type B uncertainties are correlated point-to-point. Type C uncertainties affect the scale of the data.

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Production of $\pi^0$ and $\eta$ mesons in Cu$+$Au collisions at $\sqrt{s_{_{NN}}}$=200 GeV

The PHENIX collaboration Aidala, C. ; Ajitanand, N.N. ; Akiba, Y. ; et al.
Phys.Rev.C 98 (2018) 054903, 2018.
Inspire Record 1672859 DOI 10.17182/hepdata.100192

Production of $\pi^0$ and $\eta$ mesons has been measured at midrapidity in Cu$+$Au collisions at $\sqrt{s_{_{NN}}}$=200 GeV. Measurements were performed in $\pi^0(\eta)\rightarrow\gamma\gamma$ decay channel in the 1(2)-20 GeV/$c$ transverse momentum range. A strong suppression is observed for $\pi^0$ and $\eta$ meson production at high transverse momentum in central Cu$+$Au collisions relative to the $p$$+$$p$ results scaled by the number of nucleon-nucleon collisions. In central collisions the suppression is similar to Au$+$Au with comparable nuclear overlap. The $\eta/\pi^0$ ratio measured as a function of transverse momentum is consistent with $m_T$-scaling parameterization down to $p_T=$2 GeV/$c$, its asymptotic value is constant and consistent with Au$+$Au and $p$$+$$p$ and does not show any significant dependence on collision centrality. Similar results were obtained in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions as well as in $e^+e^-$ collisions in a range of collision energies $\sqrt{s_{_{NN}}}=$3--1800 GeV. This suggests that the quark-gluon-plasma medium produced in Cu$+$Cu collisions either does not affect the jet fragmentation into light mesons or it affects the $\pi^0$ and $\eta$ the same way.

48 data tables

$\pi^0$ spectra from figure 3a from minimum bias Cu+Au collisions. Type A uncertainties are uncorrelated point-to-point. Type B uncertainties are correlated point-to-point. Type C uncertainties affect the scale of the data.

$\pi^0$ spectra from figure 3a from 0-10% central Cu+Au collisions. Type A uncertainties are uncorrelated point-to-point. Type B uncertainties are correlated point-to-point. Type C uncertainties affect the scale of the data.

$\pi^0$ spectra from figure 3a from 10-20% central Cu+Au collisions. Type A uncertainties are uncorrelated point-to-point. Type B uncertainties are correlated point-to-point. Type C uncertainties affect the scale of the data.

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Transverse energy production and charged-particle multiplicity at midrapidity in various systems from $\sqrt{s_{NN}}=7.7$ to 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.C 93 (2016) 024901, 2016.
Inspire Record 1394433 DOI 10.17182/hepdata.96601

Measurements of midrapidity charged particle multiplicity distributions, $dN_{\rm ch}/d\eta$, and midrapidity transverse-energy distributions, $dE_T/d\eta$, are presented for a variety of collision systems and energies. Included are distributions for Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$, 130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, Cu$+$Cu collisions at $\sqrt{s_{_{NN}}}=200$ and 62.4 GeV, Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV, U$+$U collisions at $\sqrt{s_{_{NN}}}=193$ GeV, $d$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV, $^{3}$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV, and $p$$+$$p$ collisions at $\sqrt{s_{_{NN}}}=200$ GeV. Centrality-dependent distributions at midrapidity are presented in terms of the number of nucleon participants, $N_{\rm part}$, and the number of constituent quark participants, $N_{q{\rm p}}$. For all $A$$+$$A$ collisions down to $\sqrt{s_{_{NN}}}=7.7$ GeV, it is observed that the midrapidity data are better described by scaling with $N_{q{\rm p}}$ than scaling with $N_{\rm part}$. Also presented are estimates of the Bjorken energy density, $\varepsilon_{\rm BJ}$, and the ratio of $dE_T/d\eta$ to $dN_{\rm ch}/d\eta$, the latter of which is seen to be constant as a function of centrality for all systems.

28 data tables

Transverse energy in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

Multiplicity in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

Transverse energy in Au+Au collisions at $\sqrt{s_{NN}}$ = 130 GeV

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Azimuthal anisotropy of pi^0 and eta mesons in Au+Au collisions at sqrt(s_NN)=200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.C 88 (2013) 064910, 2013.
Inspire Record 1254476 DOI 10.17182/hepdata.96550

The azimuthal anisotropy coefficients v_2 and v_4 of pi^0 and eta mesons are measured in Au+Au collisions at sqrt(s_NN)=200 GeV, as a function of transverse momentum p_T (1-14 GeV/c) and centrality. The extracted v_2 coefficients are found to be consistent between the two meson species over the measured p_T range. The ratio of v_4/v_2^2 for pi^0 mesons is found to be independent of p_T for 1-9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with p_T. Furthermore, the ratio of v_4/v_2^2 is systematically larger in central collisions, which may reflect the combined effects of fluctuations in the initial collision geometry and finite viscosity in the evolving medium.

10 data tables

$\eta$ meson $v_2, 0-20\%$ centrality

$\eta$ meson $v_2, 20-60\%$ centrality

$\pi^0$ meson $v_4, 0-20\%$ centrality

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Version 2
Neutral pion production with respect to centrality and reaction plane in Au+Au collisions at sqrt(s_NN)=200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.C 87 (2013) 034911, 2013.
Inspire Record 1127262 DOI 10.17182/hepdata.96561

The PHENIX experiment has measured the production of neutral pions in Au+Au collisions at sqrt(s_NN)=200 GeV. The new data offer a fourfold increase in recorded luminosity, providing higher precision and a larger reach in transverse momentum, p_T, to 20 GeV/c. The production ratio of eta/pi^0 is 0.46+/-0.01(stat)+/-0.05(syst), constant with p_T and collision centrality. The observed ratio is consistent with earlier measurements, as well as with the p+p and d+Au values. The production of pi^0 is suppressed by a factor of 5, as in earlier findings. However, with the improved statistical precision a small but significant rise of the nuclear modification factor, R_AA, vs p_T, with a slope of 0.0106+/-^(0.0034)_(0.0029)[GeV/c]^-1, is discernible in central collisions. A phenomenological extraction of the average fractional parton energy loss shows a decrease with increasing p_T. To study the path length dependence of suppression, the pi^0 yield was measured at different angles with respect to the event plane; a strong azimuthal dependence of the pi^0 R_AA is observed. The data are compared to theoretical models of parton energy loss as a function of the path length, L, in the medium. Models based on pQCD are insufficient to describe the data, while a hybrid model utilizing pQCD for the hard interactions and AdS/CFT for the soft interactions is consistent with the data.

20 data tables

Invariant yields of neutral pions, all centralities

Invariant yields of neutral pions, all centralities

$\Eta/ \pi^0 ratios

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Evolution of pi^0 suppression in Au+Au collisions from sqrt(s_NN) = 39 to 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.Lett. 109 (2012) 152301, 2012.
Inspire Record 1107625 DOI 10.17182/hepdata.96533

Neutral-pion, pi^0, spectra were measured at midrapidity (|y|<0.35) in Au+Au collisions at sqrt(s_NN) = 39 and 62.4 GeV and compared to earlier measurements at 200 GeV in the 1<p_T<10 GeV/c transverse-momentum (p_T) range. The high-p_T tail is well described by a power law in all cases and the powers decrease significantly with decreasing center-of-mass energy. The change of powers is very similar to that observed in the corresponding p+p-collision spectra. The nuclear-modification factors (R_AA) show significant suppression and a distinct energy dependence at moderate p_T in central collisions. At high p_T, R_AA is similar for 62.4 and 200 GeV at all centralities. Perturbative-quantum-chromodynamics calculations that describe R_AA well at 200 GeV, fail to describe the 39 GeV data, raising the possibility that the relative importance of initial-state effects and soft processes increases at lower energies. A conclusion that the region where hard processes are dominant is reached only at higher p_T, is also supported by the x_T dependence of the x_T-scaling power-law exponent.

16 data tables

INVARIANT YIELDS

INVARIANT YIELDS

INVARIANT YIELDS

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High-pT pi^zero Production with Respect to the Reaction Plane in Au + Au Collisions at sqrt(s_NN) = 200 GeV

The PHENIX collaboration Afanasiev, S. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.C 80 (2009) 054907, 2009.
Inspire Record 816486 DOI 10.17182/hepdata.95817

Measurements of the azimuthal anisotropy of high-\pT neutral pion neutral pion production in Au+Au collisions at sqrt(s_NN) = 200 GeV by the PHENIX experiment are presented. The data included in this paper were collected during the 2004 RHIC running period and represent approximately an order of magnitude increase in the number of analyzed events relative to previously published results. Azimuthal angle distributions of pi^0s detected in the PHENIX electromagnetic calorimeters are measured relative to the reaction plane determined event-by-event using the forward and backward beam-beam counters. Amplitudes of the second Fourier component (v_2) of the angular distributions are presented as a function of pi^0 transverse momentum p_T for different bins in collision centrality. Measured reaction plane dependent pi^0 yields are used to determine the azimuthal dependence of the pi^0 suppression as a function of p_T, R_AA (Delta phi,p_T). A jet-quenching motivated geometric analysis is presented that attempts to simultaneously describe the centrality dependence and reaction plane angle dependence of the pi^0 suppression in terms of the path lengths of hypothetical parent partons in the medium. This set of results allows for a detailed examination of the influence of geometry in the collision region, and of the interplay between collective flow and jet-quenching effects along the azimuthal axis.

4 data tables

$\pi^0 v_2$ as function of centrality. All errors are absolute.

$\pi^0 v_2$ as function of centrality. All errors are absolute.

Rebinned $R_{AA}$ for $\Delta \phi$, $p_T$, and path length dependence,

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Quantitative Constraints on the Opacity of Hot Partonic Matter from Semi-Inclusive Single High Transverse Momentum Pion Suppression in Au+Au collisions at sqrt(s_NN) = 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, Christine Angela ; et al.
Phys.Rev.C 77 (2008) 064907, 2008.
Inspire Record 777211 DOI 10.17182/hepdata.95815

The PHENIX experiment has measured the suppression of semi-inclusive single high transverse momentum pi^0's in Au+Au collisions at sqrt(s_NN) = 200 GeV. The present understanding of this suppression is in terms of energy-loss of the parent (fragmenting) parton in a dense color-charge medium. We have performed a quantitative comparison between various parton energy-loss models and our experimental data. The statistical point-to-point uncorrelated as well as correlated systematic uncertainties are taken into account in the comparison. We detail this methodology and the resulting constraint on the model parameters, such as the initial color-charge density dN^g/dy, the medium transport coefficient <q^hat>, or the initial energy-loss parameter epsilon_0. We find that high transverse momentum pi^0 suppression in Au+Au collisions has sufficient precision to constrain these model dependent parameters at the +/1 20%-25% (one standard deviation) level. These constraints include only the experimental uncertainties, and further studies are needed to compute the corresponding theoretical uncertainties.

1 data table

$\pi^0$ $0-5\%$ centrality


K*(892) resonance production in Au + Au and p + p collisions at s(NN)**(1/2) = 200-GeV at STAR.

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 71 (2005) 064902, 2005.
Inspire Record 666578 DOI 10.17182/hepdata.100595

The short-lived $K(892)^{*}$ resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of $K^{*}$ in $\sqrt{s_{_{NN}}}$ = 200 GeV Au+Au and $p+p$ collisions reconstructed via its hadronic decay channels $K(892)^{*0} \to K\pi$ and $K(892)^{*\pm} \to K_S^0\pi^{\pm}$ using the STAR detector at RHIC. The $K^{*0}$ mass has been studied as a function of $p_T$ in minimum bias $p+p$ and central Au+Au collisions. The $K^{*}$ $p_T$ spectra for minimum bias $p+p$ interactions and for Au+Au collisions in different centralities are presented. The $K^{*}/K$ yield ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias $p+p$ collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. A significant non-zero $K^{*0}$ elliptic flow ($v_2$) is observed in Au+Au collisions and compared to the $K_S^0$ and $\Lambda$ $v_2$. The nuclear modification factor of $K^{*}$ at intermediate $p_{T}$ is similar to that of $K_{S}^{0}$, but different from $\Lambda$. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate $p_T$ ($2 < p_T \leq 4$ GeV/$c$).

22 data tables

$K_S^0$ signal observed in the $\pi^+\pi^−$ invariant mass distribution reconstructed from the decay topology method via $K_S^0->\pi^+\pi^−$ in $p+p$ collisions. The dashed curve depicts the Gaussian fit function plus a linear function representing the background.

The $K\pi$ invariant mass distributions after event-mixing background subtraction (open star symbols) and like-sign background subtraction with different daughter momentum cuts (0.2 < Kaon and Pion p < 10 GeV/$c$ for filled square symbols, 0.2 < Kaon $p$ < 0.7 GeV/$c$ and 0.2 < Pion $p$ < 10 GeV/$c$ for open triangle symbols) demonstrating the sources of the residual background in minimum bias Au+Au collisions. The open triangle symbols have been scaled up by a factor of 3 in order to increase the visibility. The arrow depicts the standard $K^{*0}$ mass of 896.1 MeV/$c^2$.

The $K\pi$ invariant mass distribution integrated over the $K^*$ $p_T$ for central Au+Au (upper panel) and minimum bias $p + p$ (lower panel) interactions after the mixed-event background subtraction. The solid curves are the fits to Eq. 5 with $T_{fo}$ = 120 MeV and $p_T$ = 1.8 GeV/$c$ for central Au+Au and $T_{fo}$ = 160 MeV and $p_T$ = 0.8 GeV/$c$ for p+p, respectively. The dashed lines are the linear function representing the residual background.

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Photon and neutral pion production in Au + Au collisions at s(NN)**(1/2) = 130-GeV.

The STAR collaboration Adams, J. ; Adler, C. ; Aggarwal, M.M. ; et al.
Phys.Rev.C 70 (2004) 044902, 2004.
Inspire Record 642374 DOI 10.17182/hepdata.98925

We report the first inclusive photon measurements about mid-rapidity (|y|<0.5) from Au+Au collisions at sqrt(s_{NN}) = 130 GeV at RHIC. Photon pair conversions were reconstructed from electron and positron tracks measured with the Time Projection Chamber (TPC) of the STAR experiment. With this method, an energy resolution of Delta(E)/E = 2% at 0.5 GeV has been achieved. Reconstructed photons have also been used to measure the transverse momentum (pt) spectra of pi0 mesons about mid-rapidity (|y|<1) via the pi0 -> photon photon decay channel. The fractional contribution of the pi0 -> photon photon decay to the inclusive photon spectrum decreases by 20% +/- 5% between pt = 1.65 GeV/c and pt = 2.4 GeV/c in the most central events, indicating that relative to pi0 -> photon photon decay the contribution of other photon sources is substantially increasing.

9 data tables

Data for the electron-positron invariant mass plots

dE/dx deviant distributions of positive daughters

Data for the number of reconstructed photon conversions as a function of conversion location plots

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