cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.17182/hepdata.143067.v1/t2
title: "Figure 28" of "Dielectron production in Au$+$Au collisions at $\sqrt{s_{NN}}$=200 GeV"

description: Invariant mass spectrum of $e^+e^-$ pairs in MB Au+Au collisions within the PHENIX acceptance compared to the cocktail of expected decays.
description: We present measurements of $e^+e^−$ production at midrapidity in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass ($m_{ee}$ &lt; 5 GeV/$c^2$) and pair transverse momentum ($p_T$ &lt; 5 GeV/$c$), for minimum bias and for five centrality classes. The $e^+e^-$ yield is compared to the expectations from known sources. In the low-mass region ($m_{ee}$ = 0.30 - 0.76 GeV/$c^2$) there is an enhancement that increases with centrality and is distributed over the entire pair $p_T$ range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to 2.3 $\pm$ 0.4(stat) $\pm$ 0.4(syst) $\pm$ 0.2$^{model}$ or to 1.7 $\pm$ 0.3(stat) $\pm$ 0.3(syst) $\pm$ 0.2$^{model}$ for minimum bias collisions when the open-heavy-flavor contribution is calculated with PYTHIA or MC@NLO, respectively. The inclusive mass and $p_T$ distributions as well as the centrality dependence are well reproduced by model calculations where the enhancement mainly originates from the melting of the $\rho$ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region ($m_{ee}$ = 1.2 - 2.8 GeV/$c^2$), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.
DOI: 10.17182/hepdata.143073.v1/t1
title: "Figure 1a" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: $p$/$\pi^+$ and $p$/$\pi^-$ ratios for central (0-10%) mid-central (20-30%) and peripheral (60-92%) Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143073.v1/t2
title: "Figure 1b" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: $p$/$\pi^-$ and $p$/$\pi^0$ ratios for central (0-10%) mid-central (20-30%) and peripheral (60-92%) Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143073.v1/t3
title: "Figure 2" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: $p$ and $\bar{p}$ invariant yields scaled by $N_{coll}$. Error bars are statistical. Systematic errors on $N_{coll}$ range from ~ 10% for central to ~ 28% for 60-92% centrality. Multiplicity dependent normalization errors are ~3%.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143073.v1/t4
title: "Figure 3a" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: Nucelar modification factor $R_{CP}$ for ($p+\bar{p}$)/2.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143073.v1/t5
title: "Figure 3b" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: Nucelar modification factor $R_{CP}$ for $\pi^0$.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143073.v1/t6
title: "Figure 4a" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: Charged hadron to $\pi^0$ ratio in central (0-10%) Au+Au collisions.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143073.v1/t7
title: "Figure 4b" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: Charged hadron to $\pi^0$ ratio in peripheral (60-92%) Au+Au collisions. The peripheral data points are offset by +130 MeV/$c$ for clarity.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143073.v1/t8
title: "Figure 4c" of "Scaling properties of proton and anti-proton production in s(NN)**(1/2) = 200-GeV Au + Au collisions."

description: Systematic error on normalization a) common to both centralities b) that can move the $h$/$\pi^0$ ratios for each centrality independent of the other.
description: We report on the yield of protons and anti-protons, as a function of centrality and transverse momentum, in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured at mid-rapidity by the PHENIX experiment at RHIC. In central collisions at intermediate transverse momenta (1.5 &lt; $p_T$ &lt; 4.5 GeV/$c$) a significant fraction of all produced particles are protons and anti-protons. They show a centrality-scaling behavior different from that of pions. The $\bar{p}$/$\pi$ and $p$/$\pi$ ratios are enhanced compared to peripheral Au+Au, $p$+$p$, and $e^+$$e^-$ collisions. This enhancement is limited to $p_T$ &lt; 5 GeV/$c$ as deduced from the ratio of charged hadrons to $\pi^0$ measured in the range 1.5 &lt; $p_T$ &lt; 9 GeV/c.
DOI: 10.17182/hepdata.143074.v1/t1
title: "Figure 13" of "Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV"

description: The cross section results for forward neutron production in $p$+$p$ collisions at $\sqrt{s}$ = 200 GeV are shown. Two different forms, exponential and Gaussian, were used for the $p_T$ distribution. The integrated $p_T$ region for each bin is 0 &lt; $p_T$ &lt; 0.11$x_F$ GeV/$c$.
description: The energy dependence of the single-transverse-spin asymmetry, $A_N$, and the cross section for neutron production at very forward angles were measured in the PHENIX experiment at RHIC for polarized $p$+$p$ collisions at $\sqrt{s}$ = 200 GeV. The neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad. We report results for neutrons with momentum fraction of $x_F$ = 0.45 to 1.0. The energy dependence of the measured cross sections were consistent with $x_F$ scaling, compared to measurements by an ISR experiment which measured neutron production in unpolarized $p$+$p$ collisions at $\sqrt{s}$ = 30.6 - 62.7 GeV. The cross sections for large $x_F$ neutron production for $p$+$p$ collisions, as well as those in $e$+$p$ collisions measured at HERA, are described by a pion exchange mechanism. The observed forward neutron asymmetries were large, reaching $A_N$ = -0.08 $\pm$ 0.02 for $x_F$ = 0.8; the measured backward asymmetries, for negative $x_F$, were consistent with zero. The observed asymmetry for forward neutron production is discussed within the pion exchange framework, with interference between the spin-flip amplitude due to the pion exchange and nonflip amplitudes from all Reggeon exchanges. Within the pion exchange description, the measured neutron asymmetry is sensitive to the contribution of other Reggeon exchanges even for small amplitudes.
DOI: 10.17182/hepdata.143074.v1/t2
title: "Figure 18a" of "Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV"

description: The $x_F$ dependence of $A_N$ for neutron production in the ZDC trigger sample.
description: The energy dependence of the single-transverse-spin asymmetry, $A_N$, and the cross section for neutron production at very forward angles were measured in the PHENIX experiment at RHIC for polarized $p$+$p$ collisions at $\sqrt{s}$ = 200 GeV. The neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad. We report results for neutrons with momentum fraction of $x_F$ = 0.45 to 1.0. The energy dependence of the measured cross sections were consistent with $x_F$ scaling, compared to measurements by an ISR experiment which measured neutron production in unpolarized $p$+$p$ collisions at $\sqrt{s}$ = 30.6 - 62.7 GeV. The cross sections for large $x_F$ neutron production for $p$+$p$ collisions, as well as those in $e$+$p$ collisions measured at HERA, are described by a pion exchange mechanism. The observed forward neutron asymmetries were large, reaching $A_N$ = -0.08 $\pm$ 0.02 for $x_F$ = 0.8; the measured backward asymmetries, for negative $x_F$, were consistent with zero. The observed asymmetry for forward neutron production is discussed within the pion exchange framework, with interference between the spin-flip amplitude due to the pion exchange and nonflip amplitudes from all Reggeon exchanges. Within the pion exchange description, the measured neutron asymmetry is sensitive to the contribution of other Reggeon exchanges even for small amplitudes.
DOI: 10.17182/hepdata.143074.v1/t3
title: "Figure 18b" of "Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV"

description: The $x_F$ dependence of $A_N$ for neutron production for the ZDC$\otimes$BBC trigger sample.
description: The energy dependence of the single-transverse-spin asymmetry, $A_N$, and the cross section for neutron production at very forward angles were measured in the PHENIX experiment at RHIC for polarized $p$+$p$ collisions at $\sqrt{s}$ = 200 GeV. The neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad. We report results for neutrons with momentum fraction of $x_F$ = 0.45 to 1.0. The energy dependence of the measured cross sections were consistent with $x_F$ scaling, compared to measurements by an ISR experiment which measured neutron production in unpolarized $p$+$p$ collisions at $\sqrt{s}$ = 30.6 - 62.7 GeV. The cross sections for large $x_F$ neutron production for $p$+$p$ collisions, as well as those in $e$+$p$ collisions measured at HERA, are described by a pion exchange mechanism. The observed forward neutron asymmetries were large, reaching $A_N$ = -0.08 $\pm$ 0.02 for $x_F$ = 0.8; the measured backward asymmetries, for negative $x_F$, were consistent with zero. The observed asymmetry for forward neutron production is discussed within the pion exchange framework, with interference between the spin-flip amplitude due to the pion exchange and nonflip amplitudes from all Reggeon exchanges. Within the pion exchange description, the measured neutron asymmetry is sensitive to the contribution of other Reggeon exchanges even for small amplitudes.
DOI: 10.17182/hepdata.143075.v1/t1
title: "Figure 10" of "Direct-Photon Production in p+p Collisions at sqrt(s)=200 GeV at Midrapidity"

description: Cross section of midrapidity inclusive-direct photon production in $p+p$ collisions at $\sqrt{s}$ = 200 GeV as a function of transverse momentum ($p_T$). Asymmetric statistical uncertainties occur in $p_T$ bins with no tagged $π^0$ counts.
description: The differential cross section for the production of direct photons in $p+p$ collisions at $\sqrt{s}$ = 200 GeV at midrapidity was measured in the PHENIX detector at the Relativistic Heavy Ion Collider. Inclusive-direct photons were measured in the transverse momentum range from 5.5–25 GeV/$c$, extending the range beyond previous measurements. Event structure was studied with an isolation criterion. Next-to-leading-order perturbative-quantum-chromodynamics calculations give a good description of the spectrum. When the cross section is expressed versus $x_T$, the PHENIX data are seen to be in agreement with measurements from other experiments at different center-of-mass energies.
DOI: 10.17182/hepdata.143075.v1/t2
title: "Figure 13a" of "Direct-Photon Production in p+p Collisions at sqrt(s)=200 GeV at Midrapidity"

description: Ratio of isolated/inclusive-direct photon (Fig. 13). Upper(+) and lower bounds(-) on systematics can be different, and are listed separately.
description: The differential cross section for the production of direct photons in $p+p$ collisions at $\sqrt{s}$ = 200 GeV at midrapidity was measured in the PHENIX detector at the Relativistic Heavy Ion Collider. Inclusive-direct photons were measured in the transverse momentum range from 5.5–25 GeV/$c$, extending the range beyond previous measurements. Event structure was studied with an isolation criterion. Next-to-leading-order perturbative-quantum-chromodynamics calculations give a good description of the spectrum. When the cross section is expressed versus $x_T$, the PHENIX data are seen to be in agreement with measurements from other experiments at different center-of-mass energies.
DOI: 10.17182/hepdata.143075.v1/t3
title: "Figure 13b" of "Direct-Photon Production in p+p Collisions at sqrt(s)=200 GeV at Midrapidity"

description: Ratio of isolated/inclusive photon from $π^0$ (Fig. 13).
description: The differential cross section for the production of direct photons in $p+p$ collisions at $\sqrt{s}$ = 200 GeV at midrapidity was measured in the PHENIX detector at the Relativistic Heavy Ion Collider. Inclusive-direct photons were measured in the transverse momentum range from 5.5–25 GeV/$c$, extending the range beyond previous measurements. Event structure was studied with an isolation criterion. Next-to-leading-order perturbative-quantum-chromodynamics calculations give a good description of the spectrum. When the cross section is expressed versus $x_T$, the PHENIX data are seen to be in agreement with measurements from other experiments at different center-of-mass energies.
DOI: 10.17182/hepdata.143112.v1/t2
title: "Figure 2a" of "J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV"

description: $J/\psi$ invariant yields are shown for Au+Au collisions at 39 and 62.4 GeV as a function of the number of participating nucleons.
description: We present measurements of the $J/\psi$ invariant yields in $\sqrt{s_{NN}}$ = 39 and 62.4 GeV Au+Au collisions at forward rapidity (1.2 &lt; $|y|$ &lt; 2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au+Au collisions ($R_{CP}$) and for various centrality selections in Au+Au relative to scaled $p$+$p$ cross sections obtained from other measurements ($R_{AA}$). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.
DOI: 10.17182/hepdata.143112.v1/t1
title: "Table 4" of "J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV"

description: Estimates used for the 39- and 62.4-GeV $J/\psi$ $p$+$p$ cross sections along with their uncertainties.
description: We present measurements of the $J/\psi$ invariant yields in $\sqrt{s_{NN}}$ = 39 and 62.4 GeV Au+Au collisions at forward rapidity (1.2 &lt; $|y|$ &lt; 2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au+Au collisions ($R_{CP}$) and for various centrality selections in Au+Au relative to scaled $p$+$p$ cross sections obtained from other measurements ($R_{AA}$). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.
DOI: 10.17182/hepdata.143112.v1/t3
title: "Figure 2b" of "J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV"

description: $J/\psi$ invariant yields are shown for Au+Au collisions at 39 and 62.4 GeV as a function of the number of participating nucleons.
description: We present measurements of the $J/\psi$ invariant yields in $\sqrt{s_{NN}}$ = 39 and 62.4 GeV Au+Au collisions at forward rapidity (1.2 &lt; $|y|$ &lt; 2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au+Au collisions ($R_{CP}$) and for various centrality selections in Au+Au relative to scaled $p$+$p$ cross sections obtained from other measurements ($R_{AA}$). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.
DOI: 10.17182/hepdata.143112.v1/t4
title: "Figure 4" of "J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV"

description: $J/\psi$ $R_{CP}$ for 0-20%, 20-40%, and 40-60% (central) relative to 60-86% (peripheral) Au+Au collisions at 62.4 GeV. Type A errors are point-to-point uncorrelated, Type B errors are point-to-point correlated, and Type C are global systematic from the uncertainty in the peripheral $$ value.
description: We present measurements of the $J/\psi$ invariant yields in $\sqrt{s_{NN}}$ = 39 and 62.4 GeV Au+Au collisions at forward rapidity (1.2 &lt; $|y|$ &lt; 2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au+Au collisions ($R_{CP}$) and for various centrality selections in Au+Au relative to scaled $p$+$p$ cross sections obtained from other measurements ($R_{AA}$). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.
DOI: 10.17182/hepdata.143112.v1/t5
title: "Figure 5" of "J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV"

description: $J/\psi$ $R_{CP}$ for 0-40% (central) relative to 40-86% (peripheral) Au+Au collisions at 39 GeV. Type A errors are point-to-point uncorrelated, Type B errors are point-to-point correlated, and Type C are global systematic from the uncertainty in the peripheral $$ value.
description: We present measurements of the $J/\psi$ invariant yields in $\sqrt{s_{NN}}$ = 39 and 62.4 GeV Au+Au collisions at forward rapidity (1.2 &lt; $|y|$ &lt; 2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au+Au collisions ($R_{CP}$) and for various centrality selections in Au+Au relative to scaled $p$+$p$ cross sections obtained from other measurements ($R_{AA}$). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.