Harding, D.J.
Max results
Sort by Reverse order

Showing 10 of 1191 results

Date

Suppression of away-side jet fragments with respect to the 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 84 (2011) 024904, 2011.
Inspire Record 872172 DOI 10.17182/hepdata.96510

Pair correlations between large transverse momentum neutral pion triggers (p_T=4--7 GeV/c) and charged hadron partners (p_T=3--7 GeV/c) in central (0--20%) and midcentral (20--60%) Au+Au collisions are presented as a function of trigger orientation with respect to the reaction plane. The particles are at larger momentum than where jet shape modifications have been observed, and the correlations are sensitive to the energy loss of partons traveling through hot dense matter. An out-of-plane trigger particle produces only 26+/-20% of the away-side pairs that are observed opposite of an in-plane trigger particle. In contrast, near-side jet fragments are consistent with no suppression or dependence on trigger orientation with respect to the reaction plane. These observations are qualitatively consistent with a picture of little near-side parton energy loss either due to surface bias or fluctuations and increased away-side parton energy loss due to a long path through the medium. The away-side suppression as a function of reaction-plane angle is shown to be sensitive to both the energy loss mechanism in and the space-time evolution of heavy-ion collisions.

22 data tables
cfs

Delta phi / Correlation Function 3-4 GeV/c partners

cfs_ave

Delta phi / Correlation Function 3-4 GeV/c partners

cfsall_00-20 3-4

$p^{a}_{T} = 3-4$ GeV/$c$

More…

Measurements of Dihadron Correlations Relative to the Event Plane in Au+Au Collisions at $\sqrt{s_{NN}}=200$ GeV

The STAR collaboration Agakishiev, H. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Chin.Phys.C 45 (2021) 044002, 2021.
Inspire Record 872067 DOI 10.17182/hepdata.102351

Dihadron azimuthal correlations containing a high transverse momentum ($p_T$) trigger particle are sensitive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium, i.e. jet-quenching. Previous measurements revealed a strong modification to dihadron azimuthal correlations in Au+Au collisions with respect to p+p and d+Au collisions. The modification increases with the collision centrality, suggesting a path-length or energy density dependence to the jet-quenching effect. This paper reports STAR measurements of dihadron azimuthal correlations in mid-central (20-60%) Au+Au collisions at $\sqrt{s_{_{\rm NN}}}=200$ GeV as a function of the trigger particle's azimuthal angle relative to the event plane, $\phi_s=|\phi_t-\psi_{\rm EP}|$. The azimuthal correlation is studied as a function of both the trigger and associated particle $p_T$. The subtractions of the combinatorial background and anisotropic flow, assuming Zero Yield At Minimum (ZYAM), are described. The correlation results are first discussed with subtraction of the even harmonic (elliptic and quadrangular) flow backgrounds. The away-side correlation is strongly modified, and the modification varies with $\phi_s$, with a double-peak structure for out-of-plane trigger particles. The near-side ridge (long range pseudo-rapidity $\Delta\eta$ correlation) appears to drop with increasing $\phi_s$ while the jet-like component remains approximately constant. The correlation functions are further studied with subtraction of odd harmonic triangular flow background arising from fluctuations. It is found that the triangular flow, while responsible for the majority of the amplitudes, is not sufficient to explain the $\phi_s$-dependence of the ridge or the away-side double-peak structure. ...

899 data tables
data table 0

red data points

data table 1

black histogram

data table 2

flow background with default flow Au+Au 20-60%, 4<p_{\text{T}}^{(t)}<6 GeV/c, 2<p_{\text{T}}^{(a)}<4 GeV/c, slice 0

More…

Version 2
Strange and Multi-strange Particle Production in Au+Au Collisions at $\sqrt{s_{NN}}$ = 62.4 GeV

The STAR collaboration Aggarwal, M.M. ; Ahammed, Z. ; Alakhverdyants, A.V. ; et al.
Phys.Rev.C 83 (2011) 024901, 2011.
Inspire Record 871561 DOI 10.17182/hepdata.96847

We present results on strange and multi-strange particle production in Au+Au collisions at $\sqrt{s_{NN}}=62.4$ GeV as measured with the STAR detector at RHIC. Mid-rapidity transverse momentum spectra and integrated yields of $K^{0}_{S}$, $\Lambda$, $\Xi$, $\Omega$ and their anti-particles are presented for different centrality classes. The particle yields and ratios follow a smooth energy dependence. Chemical freeze-out parameters, temperature, baryon chemical potential and strangeness saturation factor obtained from the particle yields are presented. Intermediate transverse momentum ($p_T$) phenomena are discussed based on the ratio of the measured baryon-to-meson spectra and nuclear modification factor. The centrality dependence of various measurements presented show a similar behavior as seen in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

29 data tables
Figure 2

Correction factors (acceptance × efficiency) for the most central events ( 0−5% for KS0, Λ and Ξ; 0−20% for Ω) at mid-rapidity (|y| < 1) as a function of pT for the different particle species as obtained via embedding. The branching ratio of the measured decay channel is not factored into this plot.

Figure 3 a)

Efficiency corrected pT spectra for the different centrality bins and for the various particles. Note that 7 centrality bins have been used for the KS0 and the Λ while only 6 and 3 have been used for the Ξ and Ω, respectively. Errors are statistical only. The Λ spectra are corrected for the feed-down of the Ξ decay.

Figure 3 b)

Efficiency corrected pT spectra for the different centrality bins and for the various particles. Note that 7 centrality bins have been used for the KS0 and the Λ while only 6 and 3 have been used for the Ξ and Ω, respectively. Errors are statistical only. The Λ spectra are corrected for the feed-down of the Ξ decay.

More…

Cold Nuclear Matter Effects on J/psi Yields as a Function of Rapidity and Nuclear Geometry in Deuteron-Gold Collisions at sqrt(s_NN) = 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.Lett. 107 (2011) 142301, 2011.
Inspire Record 871818 DOI 10.17182/hepdata.146014

We present measurements of J/psi yields in d+Au collisions at sqrt(s_NN) = 200 GeV recorded by the PHENIX experiment and compare with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/psi rapidity (-2.2 < y < 2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. To remove model dependent systematic uncertainties we also compare the data to a simple geometric model. We find that calculations where the nuclear modification is linear or exponential in the density weighted longitudinal thickness are difficult to reconcile with the forward rapidity data.

10 data tables
Figure 1a

$J/\psi$ $B_{ll}$ $dN/dy$ in $p+p$ collisions as a function of rapidity. (All uncertainties are absolute. The sys. A uncertainty includes both the statistical uncertainty and the point-to-point uncorrelated systematic, sys. B represents uncertainties that are correlated from point to point, and sys. C represents uncertainties in the overall normalization.)

Figure 1b

$J/\psi$ $B_{ll}$ $dN/dy$ in $d$+Au collisions as a function of rapidity. The $d$+Au yields are divided by the average number of nucleon-nucleon collisions $\langle N_{coll}$(0-100%)$\rangle$ = 7.6. (All uncertainties are absolute. The sys. A uncertainty includes both the statistical uncertainty and the point-to-point uncorrelated systematic, sys. B represents uncertainties that are correlated from point to point, and sys. C represents uncertainties in the overall normalization.)

Figure 1c

Mid rapidity $d$+Au —> $e^+e^-$ $J/\psi$ invariant yields at $\sqrt{s}$=200 GeV. (All uncertainties are absolute. The sys. A uncertainty includes both the statistical uncertainty and the point-to-point uncorrelated systematic, sys. B represents uncertainties that are correlated from point to point, and sys. C represents uncertainties in the overall normalization.)

More…

Measurement of the parity-violating longitudinal single-spin asymmetry for $W^{\pm}$ boson production in polarized proton-proton collisions at $\sqrt{s} = 500 $GeV

The STAR collaboration Aggarwal, M.M. ; Ahammed, Z. ; Alakhverdyants, A.V. ; et al.
Phys.Rev.Lett. 106 (2011) 062002, 2011.
Inspire Record 866968 DOI 10.17182/hepdata.104930

We report the first measurement of the parity violating single-spin asymmetries for midrapidity decay positrons and electrons from $W^{+}$ and $W^{-}$ boson production in longitudinally polarized proton-proton collisions at $\sqrt{s}=500 $GeV by the STAR experiment at RHIC. The measured asymmetries, $A^{W^+}_{L}=-0.27\pm 0.10\/({\rm stat.})\pm 0.02\/({\rm syst.}) \pm 0.03\/({\rm norm.})$ and $A^{W^-}_{L}=0.14\pm 0.19\/({\rm stat.})\pm 0.02 \/({\rm syst.})\pm 0.01\/({\rm norm.})$, are consistent with theory predictions, which are large and of opposite sign. These predictions are based on polarized quark and antiquark distribution functions constrained by polarized DIS measurements.

5 data tables
Figure 3 - W-

$E^e_T$ for W+ (bottom) and W− (top) events showing the candidate histograms in black, the full background estimates in blue and the signal distributions in yellow.

Figure 3 - W+

$E^e_T$ for W+ (bottom) and W− (top) events showing the candidate histograms in black, the full background estimates in blue and the signal distributions in yellow.

Figure 4 - W-

Longitudinal single-spin asymmetry, AL, for W± events as a function of the leptonic pseudorapidity, $\eta_e$, for 25 < $E^e_T$ < 50 GeV in comparison to theory predictions

More…

Cross Section and Parity Violating Spin Asymmetries of $W^\pm$ Boson Production in Polarized $p+p$ Collisions at $\sqrt{s}=500$ GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.Lett. 106 (2011) 062001, 2011.
Inspire Record 866922 DOI 10.17182/hepdata.143617

Large parity violating longitudinal single spin asymmetries A^{e^-}_L= -0.86^{+0.14}_{-0.30} and A^{e^+}_L= 0.88^{+0.12}_{-0.71} are observed for inclusive high transverse momentum electrons and positrons in polarized pp collisions at a center of mass energy of \sqrt{s}=500\ GeV with the PHENIX detector at RHIC. These e^{+/-} come mainly from the decay of W^{+/-} and Z^0 bosons, and the asymmetries directly demonstrate parity violation in the couplings of the W^{\pm} to the light quarks. The observed electron and positron yields were used to estimate W^\pm boson production cross sections equal to \sigma(pp \to W^+ X) \times BR(W^ \to \nu_e)= 144.1+/-21.2(stat)^{+3.4}_{-10.3}(syst) +/- 15%(norm) pb, and \sigma(pp \to W^{-}X) \times BR(W^\to e^-\bar{\nu_e}) = 31.7+/-12.1(stat)^{+10.1}_{-8.2}(syst)+/-15%(norm) pb.

3 data tables
Figure 1

The spectra of positive and negative candidates before and after an isolation cut. The computation of the background before the isolation cut is described in the text. The background band after the isolation cut is computed by scaling the background before the isolation cut by the isolation cut efficiency measured in the background region (12< $p_T$ <20GeV/$c$). The systematic errors include uncertainties in the photon conversion probability, the background normalization, and the background extrapoltion to $p_T$ > 30 GeV/$c$.

Figure 2a

Background subtracted spectra of positron candidates taken from all counts compared to the spectrum of W and Z decays from an NLO calculation.

Figure 2b

Background subtracted spectra of electron candidates taken from all counts compared to the spectrum of W and Z decays from an NLO calculation.


Event Structure and Double Helicity Asymmetry in Jet Production from Polarized p+p Collisions at sqrt(s) = 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.D 84 (2011) 012006, 2011.
Inspire Record 870912 DOI 10.17182/hepdata.143462

We report on event structure and double helicity asymmetry ($A_LL$) of jet production in longitudinally polarized p+p collisions at $\sqrt{s}$=200 GeV. Photons and charged particles were measured at midrapidity $|\eta| < 0.35$ with the requirement of a high-momentum ($>2$ GeV/$c$) photon in each event. Measured event structure is compared with {\sc pythia} and {\sc geant} simulations. The shape of jets and the underlying event were well reproduced at this collision energy. For the measurement of jet $A_{LL}$, photons and charged particles were clustered with a seed-cone algorithm to obtain the cluster $p_T$ sum ($p_T^{\rm reco}$). The effect of detector response and the underlying events on $p_T^{\rm reco}$ was evaluated with the simulation. The production rate of reconstructed jets is satisfactorily reproduced with the NLO pQCD jet production cross section. For $4 < p_T^{\rm reco} < 12$ GeV/$c$ with an average beam polarization of $< P > = 49%$ we measured $A_{LL} = -0.0014 \pm 0.0037^{\rm stat}$ at the lowest $p_T^{\rm reco}$ bin (4-5 GeV/$c$) and $-0.0181 \pm 0.0282^{\rm stat}$ at the highest $p_T^{\rm reco}$ bin (10-12 GeV/$c$) with a beam polarization scale error of 9.4% and a $\pT$ scale error of 10%. Jets in the measured $p_T^{\rm reco}$ range arise primarily from hard-scattered gluons with momentum fraction $0.02 < x < 0.3$ according to {\sc pythia}. The measured $A_{LL}$ is compared with predictions that assume various $\Delta G(x)$ distributions based on the GRSV parameterization. The present result imposes the limit $-1.1 < \int_{0.02}^{0.3}dx \Delta G(x, \mu^2 = 1 {\rm GeV}^2) < 0.4$ at 95% confidence level or $\int_{0.02}^{0.3}dx \Delta G(x, \mu^2 = 1 {\rm GeV}^2) < 0.5$ at 99% confidence level.

3 data tables
Figure 5

The relative yields of $q$+$q$, $q$+$g$, and $g$+$g$ subprocesses in the PYTHIA+GEANT simulation.

Figure 15

The correction factor $\epsilon^j_{trig+acc}$ for high-$p_T$ photon trigger efficiency and acceptance effect.

Figure 18

Reconstructed-jet $A_{LL}$ as a function of $p_T^{reco}$.


Cross section and double helicity asymmetry for eta mesons and their comparison to neutral pion production in p+p collisions at sqrt(s)=200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.D 83 (2011) 032001, 2011.
Inspire Record 871225 DOI 10.17182/hepdata.141644

Measurements of double-helicity asymmetries for inclusive hadron production in polarized p+p collisions are sensitive to helicity--dependent parton distribution functions, in particular to the gluon helicity distribution, Delta(g). This study focuses on the extraction of the double-helicity asymmetry in eta production: polarized p+p --> eta + X, the eta cross section, and the eta/pi^0 cross section ratio. The cross section and ratio measurements provide essential input for the extraction of fragmentation functions that are needed to access the helicity-dependent parton distribution functions.

3 data tables
Figure 3

Cross section for midrapidity inclusive of $\eta$ productions at $\sqrt{s}$ = 200 GeV as a function of $p_T$ and its comparison to NLO pQCD calculations at three different scales $\mu$. The error bars shown are the statistical and systematic uncertainties added in quadrature. Note that the fragmentation functions used in the calculations are partially constrained by this data.

Figure 5

Cross section ratio for the midrapidity production of inclusive $\eta$ to $\pi^0$ mesons at $\sqrt{s}$ = 200 GeV as a function of $p_T$. The error bars show the statistical and systematic uncertainties added in quadrature. The solid curve shows the ratio of the NLO pQCD calculations shown in Fig. 3 and the corresponding one for the $\pi^0$. The dashed curve shows the result of a PYTHIA Monte-Carlo simulation.

Figure 6

Double helicity asymmetry for midrapidity inclusive $\eta$ production from the combined 2005 and 2006 data at $\sqrt{s}$ = 200 GeV as a function of $p_T$. An additional 4.8% systematic uncertainty in the beam polarizations is not shown.


Measurement of Transverse Single-Spin Asymmetries for J/psi Production in Polarized p+p Collisions at sqrt(s) = 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.D 82 (2010) 112008, 2010.
Inspire Record 870935 DOI 10.17182/hepdata.141635

We report the first measurement of transverse single-spin asymmetries in $J/\psi$ production from transversely polarized $p+p$ collisions at $\sqrt{s} = 200$ GeV with data taken by the PHENIX experiment in 2006 and 2008. The measurement was performed over the rapidity ranges $1.2 &lt; |y| &lt; 2.2$ and $ |y| &lt; 0.35$ for transverse momenta up to 6 GeV/$c$. $J/\psi$ production at RHIC is dominated by processes involving initial-state gluons, and transverse single-spin asymmetries of the $J/\psi$ can provide access to gluon dynamics within the nucleon. Such asymmetries may also shed light on the long-standing question in QCD of the $J/\psi$ production mechanism. Asymmetries were obtained as a function of $J/\psi$ transverse momentum and Feynman-$x$, with a value of $-0.086 \pm 0.026^{\rm stat} \pm 0.003^{\rm syst}$ in the forward region. This result suggests possible nonzero trigluon correlation functions in transversely polarized protons and, if well defined in this reaction, a nonzero gluon Sivers distribution function.

0 data tables

Scaling properties at freeze-out in relativistic heavy ion collisions

The STAR collaboration Aggarwal, M.M. ; Ahammed, Z. ; Alakhverdyants, A.V. ; et al.
Phys.Rev.C 83 (2011) 034910, 2011.
Inspire Record 865572 DOI 10.17182/hepdata.104504

Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at $\sqrt{s_{NN}}$=200 and 62.4 GeV. The data are studied with hydrodynamically-motivated Blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au+Au and $pp$ collisions, the dependence of freeze-out parameters on the system size is also explored. This multi-dimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance of the initial geometrical overlap of the colliding ions. The analysis of Cu+Cu collisions, which expands the system size dependence studies from Au+Au data with detailed measurements in the smaller system, shows that the bulk freeze-out properties of charged particles studied here scale with the total charged particle multiplicity at mid-rapidity, suggesting the relevance of initial state effects.

26 data tables
Figure 3(a)

Negatively charged pion spectra from Cu+Cu collisions 200 GeV as a function of pT for different centralities.

Figure 3(b)

Negatively charged pion spectra from Cu+Cu collisions 62.4 GeV as a function of pT for different centralities.

Figure 3(c)

Negatively charged kaon spectra from Cu+Cu collisions 200 GeV as a function of pT for different centralities.

More…