Charge-dependent pair correlations relative to a third particle in $p$+Au and $d$+Au collisions at RHIC

The STAR collaboration Adam, J. ; Adamczyk, L. ; Adams, J.R. ; et al.
Phys.Lett.B 798 (2019) 134975, 2019.
Inspire Record 1738942 DOI 10.17182/hepdata.105911

Quark interactions with topological gluon configurations can induce chirality imbalance and local parity violation in quantum chromodynamics. This can lead to electric charge separation along the strong magnetic field in relativistic heavy-ion collisions -- the chiral magnetic effect (CME). We report measurements by the STAR collaboration of a CME-sensitive observable in $p$+Au and $d$+Au collisions at 200 GeV, where the CME is not expected, using charge-dependent pair correlations relative to a third particle. We observe strong charge-dependent correlations similar to those measured in heavy-ion collisions. This bears important implications for the interpretation of the heavy-ion data.

10 data tables

The $\gamma_{OS}$ correlators in p+Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC as a function of multiplicity.

The $\gamma_{SS}$ correlators in p+Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC as a function of multiplicity.

The $\gamma_{OS}$ correlators in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC as a function of multiplicity.

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Di-Jet Imbalance Measurements at $\sqrt{s_{NN}} = 200$ GeV at STAR

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 119 (2017) 062301, 2017.
Inspire Record 1486427 DOI 10.17182/hepdata.102941

We report the first di-jet transverse momentum asymmetry measurements from Au+Au and p+p collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2 GeV/c display a significantly stronger momentum imbalance in heavy-ion collisions than in the p+p reference. When re-examined with correlated soft particles included, we observe that these di-jets then exhibit a unique new feature -- momentum balance is restored to that observed in p+p for a jet resolution parameter of R=0.4, while re-balancing is not attained with a smaller value of R=0.2.

11 data tables

Normalized AJ distributions for Au+Au HT data (filled symbols) and p+p HT $\oplus$ Au+Au MB (open symbols). The red circles points are for jets found using only constituents with $p^{Cut}_{T} > 2$ GeV/$c$ and the black squares for matched jets found using constituents with $p^{Cut}_{T} > 0.2$ GeV/$c$. In all cases $R = 0.4$.

$p_{T}^{Part}$ vs. $p_{T}^{Det}$ for Leading jets with $R = 0.4$.

$p_{T}^{Part}$ vs. $p_{T}^{Det}$ for Leading jets with $R = 0.2$.

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Measurement of Transverse Single-Spin Asymmetries for Di-Jet Production in Proton-Proton Collisions at $\sqrt{s} = 200$ GeV

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.Lett. 99 (2007) 142003, 2007.
Inspire Record 751885 DOI 10.17182/hepdata.102938

We report the first measurement of the opening angle distribution between pairs of jets produced in high-energy collisions of transversely polarized protons. The measurement probes (Sivers) correlations between the transverse spin orientation of a proton and the transverse momentum directions of its partons. With both beams polarized, the wide pseudorapidity ($-1 \leq \eta \leq +2$) coverage for jets permits separation of Sivers functions for the valence and sea regions. The resulting asymmetries are all consistent with zero and considerably smaller than Sivers effects observed in semi-inclusive deep inelastic scattering (SIDIS). We discuss theoretical attempts to reconcile the new results with the sizable transverse spin effects seen in SIDIS and forward hadron production in pp collisions.

4 data tables

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated di-jet cross section with a quark (gluon) from the $+\hat{z}$ $(−\hat{z})$ beam. (c,d): Unweighted asymmetries compared with pQCD calculations [20] (histograms) for two models of quark Sivers functions fitted to SIDIS results [8]. (e,f): Asymmetries for $|\sin\zeta|$-weighted yields, compared with calculations [20, 21] based on twist-3 quark-gluon correlations. Vertical (horizontal) bars on the data indicate statistical uncertainties (bin widths). The systematic error bands exclude a $\pm12\%$ beam polarization normalization uncertainty.

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated di-jet cross section with a quark (gluon) from the $+\hat{z}$ $(−\hat{z})$ beam. (c,d): Unweighted asymmetries compared with pQCD calculations [20] (histograms) for two models of quark Sivers functions fitted to SIDIS results [8]. (e,f): Asymmetries for $|\sin\zeta|$-weighted yields, compared with calculations [20, 21] based on twist-3 quark-gluon correlations. Vertical (horizontal) bars on the data indicate statistical uncertainties (bin widths). The systematic error bands exclude a $\pm12\%$ beam polarization normalization uncertainty.

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated di-jet cross section with a quark (gluon) from the $+\hat{z}$ $(−\hat{z})$ beam. (c,d): Unweighted asymmetries compared with pQCD calculations [20] (histograms) for two models of quark Sivers functions fitted to SIDIS results [8]. (e,f): Asymmetries for $|\sin\zeta|$-weighted yields, compared with calculations [20, 21] based on twist-3 quark-gluon correlations. Vertical (horizontal) bars on the data indicate statistical uncertainties (bin widths). The systematic error bands exclude a $\pm12\%$ beam polarization normalization uncertainty.

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Mass, quark-number, and sqrt s(NN) dependence of the second and fourth flow harmonics in ultra-relativistic nucleus-nucleus collisions

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 75 (2007) 054906, 2007.
Inspire Record 741917 DOI 10.17182/hepdata.104927

We present STAR measurements of the azimuthal anisotropy parameter $v_2$ for pions, kaons, protons, $\Lambda$, $\bar{\Lambda}$, $\Xi+\bar{\Xi}$, and $\Omega + \bar{\Omega}$, along with $v_4$ for pions, kaons, protons, and $\Lambda + \bar{\Lambda}$ at mid-rapidity for Au+Au collisions at $\sqrt{s_{_{NN}}}=62.4$ and 200 GeV. The $v_2(p_T)$ values for all hadron species at 62.4 GeV are similar to those observed in 130 and 200 GeV collisions. For observed kinematic ranges, $v_2$ values at 62.4, 130, and 200 GeV are as little as 10%--15% larger than those in Pb+Pb collisions at $\sqrt{s_{_{NN}}}=17.3$ GeV. At intermediate transverse momentum ($p_T$ from 1.5--5 GeV/c), the 62.4 GeV $v_2(p_T)$ and $v_4(p_T)$ values are consistent with the quark-number scaling first observed at 200 GeV. A four-particle cumulant analysis is used to assess the non-flow contributions to pions and protons and some indications are found for a smaller non-flow contribution to protons than pions. Baryon $v_2$ is larger than anti-baryon $v_2$ at 62.4 and 200 GeV perhaps indicating either that the initial spatial net-baryon distribution is anisotropic, that the mechanism leading to transport of baryon number from beam- to mid-rapidity enhances $v_2$, or that anti-baryon and baryon annihilation is larger in the in-plane direction.

106 data tables

Minimum-bias (0–80% of the collision cross section) v2(pT ) for identified hadrons at |η| < 1 from Au+Au collisions at √sNN = 62.4 GeV. To facilitate comparisons between panels, v2 values for inclusive charged hadrons are displayed in each panel. The error bars on the data points represent statistical uncertainties. Systematic uncertainties for the identified particles are shown as shaded bands around v2 = 0.

Minimum-bias (0–80% of the collision cross section) v2(pT ) for identified hadrons at |η| < 1 from Au+Au collisions at √sNN = 62.4 GeV. To facilitate comparisons between panels, v2 values for inclusive charged hadrons are displayed in each panel. The error bars on the data points represent statistical uncertainties. Systematic uncertainties for the identified particles are shown as shaded bands around v2 = 0.

Minimum-bias (0–80% of the collision cross section) v2(pT ) for identified hadrons at |η| < 1 from Au+Au collisions at √sNN = 62.4 GeV. To facilitate comparisons between panels, v2 values for inclusive charged hadrons are displayed in each panel. The error bars on the data points represent statistical uncertainties. Systematic uncertainties for the identified particles are shown as shaded bands around v2 = 0.

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Rapidity and species dependence of particle production at large transverse momentum for d + Au collisions at s(NN)**(1/2) = 200-GeV.

The STAR collaboration Abelev, B.I. ; Adams, J. ; Aggarwal, M.M. ; et al.
Phys.Rev.C 76 (2007) 054903, 2007.
Inspire Record 726101 DOI 10.17182/hepdata.101349

We determine rapidity asymmetry in the production of charged pions, protons and anti-protons for large transverse momentum (pT) for d+Au collisions at \sqrt s_NN = 200 GeV. The identified hadrons are measured in the rapidity regions |y| < 0.5 and 0.5 < |y| < 1.0 for the pT range 2.5 < pT < 10 GeV/c. We observe significant rapidity asymmetry for charged pion and proton+anti-proton production in both rapidity regions. The asymmetry is larger for 0.5 < |y| < 1.0 than for |y|< 0.5 and is almost independent of particle type. The measurements are compared to various model predictions employing multiple scattering, energy loss, nuclear shadowing, saturation effects, and recombination, and also to a phenomenological parton model. We find that asymmetries are sensitive to model parameters and show model-preference. The rapidity dependence of \pi^{-}/\pi^{+} and \bar{p}/p ratios in peripheral d+Au and forward neutron-tagged events are used to study the contributions of valence quarks and gluons to particle production at high pT. The results are compared to calculations based on NLO pQCD and other measurements of quark fragmentation functions.

15 data tables

High transverse-momentum spectra ($p_{T} > 2.5$ GeV/c) of charged pions, protons, and antiprotons for the rapidity regions $|y| < 0.5$ (solid symbols) and $0.5 < |y| < 1.0$ (open symbols) for $d+Au$ collisions and various event centrality classes at $\sqrt{s_{NN}}=200$ GeV.

High transverse-momentum spectra ($p_{T} > 2.5$ GeV/c) of charged pions, protons, and antiprotons for the rapidity regions $|y| < 0.5$ (solid symbols) and $0.5 < |y| < 1.0$ (open symbols) for $d+Au$ collisions and various event centrality classes at $\sqrt{s_{NN}}=200$ GeV.

High transverse-momentum spectra ($p_{T} > 2.5$ GeV/c) of charged pions, protons, and antiprotons for the rapidity regions $|y| < 0.5$ (solid symbols) and $0.5 < |y| < 1.0$ (open symbols) for $d+Au$ collisions and various event centrality classes at $\sqrt{s_{NN}}=200$ GeV.

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Longitudinal double-spin asymmetry and cross section for inclusive jet production in polarized proton collisions at s**(1/2) = 200-GeV.

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.Lett. 97 (2006) 252001, 2006.
Inspire Record 723509 DOI 10.17182/hepdata.104928

We report a measurement of the longitudinal double-spin asymmetry A_LL and the differential cross section for inclusive midrapidity jet production in polarized proton collisions at sqrt(s)=200 GeV. The cross section data cover transverse momenta 5 < pT < 50 GeV/c and agree with next-to-leading order perturbative QCD evaluations. The A_LL data cover 5 < pT < 17 GeV/c and disfavor at 98% C.L. maximal positive gluon polarization in the polarized nucleon.

3 data tables

(a) Inclusive differential cross section for p+p -> jet +X at sqrt(s) = 200 GeV versus jet pT for a jet cone radius of 0.4. The symbols show MB (open squares) and HT (filled circles) data from the years 2003 and 2004 combined. The horizontal bars indicate the ranges of the pT intervals. The curve shows a NLO calculation. (b) Comparison of theory and data. The band indicates the experimental systematic uncertainty. The upper (lower) dashed line indicates the relative change of the NLO calculation when it is evaluated at &mu = pT/2 (&mu = 2pT).

(a) Inclusive differential cross section for p+p -> jet +X at sqrt(s) = 200 GeV versus jet pT for a jet cone radius of 0.4. The symbols show MB (open squares) and HT (filled circles) data from the years 2003 and 2004 combined. The horizontal bars indicate the ranges of the pT intervals. The curve shows a NLO calculation. (b) Comparison of theory and data. The band indicates the experimental systematic uncertainty. The upper (lower) dashed line indicates the relative change of the NLO calculation when it is evaluated at &mu = pT/2 (&mu = 2pT).

The longitudinal double-spin asymmetry ALL in p+p-> jet +X at sqrt(s) = 200 GeV versus jet pT. The uncertainties on the data points are statistical. The gray band indicates the systematic uncertainty from the beam polarization measurement, and the hatched band the total systematic uncertainty. The curves show predictions based on deep-inelastic scattering parametrizations of gluon polarization.


Strange baryon resonance production in s(NN)**(1/2) = 200-GeV p + p and Au + Au collisions.

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.Lett. 97 (2006) 132301, 2006.
Inspire Record 715471 DOI 10.17182/hepdata.102937

We report the measurements of $\Sigma (1385)$ and $\Lambda (1520)$ production in $p+p$ and $Au+Au$ collisions at $\sqrt{s_{NN}} = 200$ GeV from the STAR collaboration. The yields and the $p_{T}$ spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central $Au+Au$ collisions. Our results indicate that there may be a time-span between chemical and thermal freeze-out during which elastic hadronic interactions occur.

2 data tables

The transverse mass spectra for $\Sigma^{∗}$ and $\Lambda^{∗}$ in p+p and in central Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Statistical and systematical errors are included.

Resonance to stable particle ratios for p + p and Au + Au collisions. The ratios are normalized to unity in p + p and compared to thermal and UrQMD model predictions for central Au + Au [8, 12]. Statistical and systematic uncertainties are included in the error bars. (In the paper figure, K*/K dNCh/dy axis is shifted +30 for visual purposes to seperate the error bar contributions.)


Proton Lambda correlations in central Au + Au collisions at s(NN)**(1/2) = 200-GeV.

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 74 (2006) 064906, 2006.
Inspire Record 696676 DOI 10.17182/hepdata.98927

We report on p-Lambda, p-Lambda bar, p bar-Lambda and p bar-Lambda bar correlation functions constructed in central Au-Au collisions at sqrt(s_NN)=200GeV by the STAR experiment at RHIC. The proton and lambda source size is inferred from the p-Lambda and p bar-Lambda bar correlation functions. They are found to be smaller than the pion source size also measured by the STAR detector. This could be a consequence of the collision fireball's collective expansion. The p-Lambda bar and p bar-Lambda correlations, which are measured for the first time, exhibit a large anti-correlation. Annihilation channels and/or a negative real part of the spin-averaged scattering length must be included in the final-state interactions calculation to reproduce the measured correlation function.

8 data tables

Invariant mass of the selected $\Lambda$ background not substracted with $0.3 < p_t < 2.0$ GeV/c. The y axis represents the number of candidates used in this analysis.

Invariant mass of the selected $\bar{\Lambda}$ background not substracted with $0.3 < p_t < 2.0$ GeV/c. The y axis represents the number of candidates used in this analysis.

The purity and momentum-resolution corrected correlation functions $C_{true}(k^{*})$ for $p-\Lambda$, $\bar{p}-\bar{\Lambda}$ (a), $\bar{p}-\Lambda$, $p-\bar{\Lambda}$ (b). Curves correspond to fits done using the Lednicky and Lyuboshitz analytical model [12].

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Cross sections and transverse single-spin asymmetries in forward neutral pion production from proton collisions at s**(1/2) = 200-GeV.

The STAR collaboration Adams, J. ; Adler, C. ; Aggarwal, M.M. ; et al.
Phys.Rev.Lett. 92 (2004) 171801, 2004.
Inspire Record 631869 DOI 10.17182/hepdata.101348

Measurements of the production of forward high-energy pi0 mesons from transversely polarized proton collisions at \sqrt{s}=200 GeV are reported. The cross section is generally consistent with next-to-leading order perturbative QCD calculations. The analyzing power is small at x_F below about 0.3, and becomes positive and large at higher x_F, similar to the trend in data at \sqrt{s}<=20 GeV. The analyzing power is in qualitative agreement with perturbative QCD model expectations. This is the first significant spin result seen for particles produced with p_T>1 GeV/c at a polarized proton collider.

2 data tables

Inclusive $\pi^{0}$ production cross section versus leading $\pi^{0}$ energy ($E_{\pi}$). The average transverse momentum ($\langle p_{T}\rangle$) is correlated with $E_{\pi}$, as the PFPD was at a fixed pseudorapidity ($\eta$). The inner error bars are statistical, and are smaller than the symbols for most points. The outer error bars combine these with the $E_{\pi}$-dependent systematic errors. The curves are NLO pQCD calculations evaluated at $\eta=3.8$ [29-31].

Analyzing powers versus Feynman $x$ ($x_{F}$). The average transverse momentum ($\langle p_{T}\rangle$) is correlated with $x_{F}$. The solid points are for identified $\pi^{0}$ mesons. The open points are for the total energy ($E_{\scriptsize{\mbox{tot}}}$), shifted by $x_{F}+0.01$. The inner error bars are statistical, and the outer combine these with the point-to-point systematic errors. The curves are from pQCD models evaluated at $p_{T}=1.5$ GeV/c [14-17]. The $A_{N}$ values are proportional to $A^{\scriptsize{\mbox{CNI}}}_{N}$, assumed to be 0.013 at 100 GeV.


Pion kaon correlations 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.Lett. 91 (2003) 262302, 2003.
Inspire Record 624731 DOI 10.17182/hepdata.104926

Pion-kaon correlation functions are constructed from central Au+Au data taken at $\sqrt{s_{NN}} = 130$ GeV. The results suggest that pions and kaons are not emitted at the same average space-time point. Space-momentum correlations, i.e. transverse flow, lead to a space-time emission asymmetry of pions and kaons that is consistent with the data. This result provides new independent evidence that the system created at RHIC undergoes a collective transverse expansion.

7 data tables

Pion-kaon correlation functions and ratios of correlation functions. Errors are statistical only.

Pion-kaon correlation functions and ratios of correlation functions. Errors are statistical only.

Pion-kaon correlation functions and ratios of correlation functions. Errors are statistical only.

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