cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.17182/hepdata.95749.v1/t12
title: "Figure3.3: RAA vs $p_T$ in 0-12% Au+Au collisions." of "Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at $\sqrt{s_{_{NN}}} = 200$ GeV"

description: $R_{AA}$ of $K^0_S$ in central Au+Au collisions as a function of $p_T$. The curves are the calculations for $K^0_S$ $R_{AA}$ with and without jet conversion in medium [15]. Bars and boxes (bands) represent statistical and systematic uncertainties, respectively. The height of the band at unity represents the normalization uncertainty.
description: BNL-RHIC. We report transverse momentum ($p_T \leq 15$ GeV/c) spectra of $\pi^{\pm}$, $K^{\pm}$ and $p$, $\bar{p}$, $K^0_S$, and $\rho^0$ at mid-rapidity in p+p and Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Perturbative QCD calculations are consistent with $\pi^{\pm}$ spectra in p+p collisions but do not reproduce $K$ and $p$($\bar{p}$) spectra. The observed decreasing antiparticle-to-particle ratios with increasing $p_T$ provide experimental evidence for varying quark and gluon jet contributions to high-$p_T$ hadron yields. The relative hadron abundances in Au+Au at $p_T &gt; 8$ GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.
DOI: 10.17182/hepdata.95749.v1/t13
title: "Figure3.4: RAA vs $p_T$ in 0-12% Au+Au collisions." of "Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at $\sqrt{s_{_{NN}}} = 200$ GeV"

description: $R_{AA}$ of $\rho^0$ in central Au+Au collisions as a function of $p_T$. Bars and boxes (bands) represent statistical and systematic uncertainties, respectively. The height of the band at unity represents the normalization uncertainty.
description: BNL-RHIC. We report transverse momentum ($p_T \leq 15$ GeV/c) spectra of $\pi^{\pm}$, $K^{\pm}$ and $p$, $\bar{p}$, $K^0_S$, and $\rho^0$ at mid-rapidity in p+p and Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Perturbative QCD calculations are consistent with $\pi^{\pm}$ spectra in p+p collisions but do not reproduce $K$ and $p$($\bar{p}$) spectra. The observed decreasing antiparticle-to-particle ratios with increasing $p_T$ provide experimental evidence for varying quark and gluon jet contributions to high-$p_T$ hadron yields. The relative hadron abundances in Au+Au at $p_T &gt; 8$ GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.
DOI: 10.17182/hepdata.95749.v1/t14
title: "Figure3.5: Double ratio vs $p_T$ in 0-12% Au+Au collisions." of "Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at $\sqrt{s_{_{NN}}} = 200$ GeV"

description: The ratios of $R_{AA}[K^{\pm} + p(\bar{p})]$ to $R_{AA}(\pi^{\pm})$. The boxes and shaded bands represent the systematic uncertainties for $R_{AA}[K^{\pm} +p(\bar{p})]/R_{AA}(\pi^{\pm})$, respectively.
description: BNL-RHIC. We report transverse momentum ($p_T \leq 15$ GeV/c) spectra of $\pi^{\pm}$, $K^{\pm}$ and $p$, $\bar{p}$, $K^0_S$, and $\rho^0$ at mid-rapidity in p+p and Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Perturbative QCD calculations are consistent with $\pi^{\pm}$ spectra in p+p collisions but do not reproduce $K$ and $p$($\bar{p}$) spectra. The observed decreasing antiparticle-to-particle ratios with increasing $p_T$ provide experimental evidence for varying quark and gluon jet contributions to high-$p_T$ hadron yields. The relative hadron abundances in Au+Au at $p_T &gt; 8$ GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.
DOI: 10.17182/hepdata.95749.v1/t15
title: "Figure3.6: Double ratio vs $p_T$ in 0-12% Au+Au collisions." of "Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at $\sqrt{s_{_{NN}}} = 200$ GeV"

description: The ratios of $R_{AA}(K^− + \bar{p})$ to $R_{AA}(K^+ p)$. The systematic uncertainties for $R_{AA}(K^− + \bar{p})/R_{AA}(K^+ +p)$ are 2–12% and left off for clarity.
description: BNL-RHIC. We report transverse momentum ($p_T \leq 15$ GeV/c) spectra of $\pi^{\pm}$, $K^{\pm}$ and $p$, $\bar{p}$, $K^0_S$, and $\rho^0$ at mid-rapidity in p+p and Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Perturbative QCD calculations are consistent with $\pi^{\pm}$ spectra in p+p collisions but do not reproduce $K$ and $p$($\bar{p}$) spectra. The observed decreasing antiparticle-to-particle ratios with increasing $p_T$ provide experimental evidence for varying quark and gluon jet contributions to high-$p_T$ hadron yields. The relative hadron abundances in Au+Au at $p_T &gt; 8$ GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.
DOI: 10.17182/hepdata.95749.v1/t16
title: "Figure3.7: Double ratio vs $p_T$ in 0-12% Au+Au collisions." of "Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at $\sqrt{s_{_{NN}}} = 200$ GeV"

description: The ratios of $R_{AA}[\rho^0]$ to $R_{AA}(\pi^{\pm})$. The boxes and shaded bands represent the systematic uncertainties for $R_{AA}(\rho^0)/R_{AA}(\pi^{\pm})$, respectively.
description: BNL-RHIC. We report transverse momentum ($p_T \leq 15$ GeV/c) spectra of $\pi^{\pm}$, $K^{\pm}$ and $p$, $\bar{p}$, $K^0_S$, and $\rho^0$ at mid-rapidity in p+p and Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Perturbative QCD calculations are consistent with $\pi^{\pm}$ spectra in p+p collisions but do not reproduce $K$ and $p$($\bar{p}$) spectra. The observed decreasing antiparticle-to-particle ratios with increasing $p_T$ provide experimental evidence for varying quark and gluon jet contributions to high-$p_T$ hadron yields. The relative hadron abundances in Au+Au at $p_T &gt; 8$ GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.
DOI: 10.17182/hepdata.95750.v1/t1
title: "$D^0$ spectra in AuAu collisions" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: $D^0$ invariant yield at mid-rapidity ($|y| &lt; 1$) vs transverse momentum for different centrality classes. Error bars indicate statistical uncertainties and brackets depict systematic uncertainties. Global systematic uncertainties in B.R. are not plotted. Solid and dashed lines depict Levy function fits.
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t2
title: "$D^0$ spectra in pp collisions" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: $D^0$ spectra in pp collisions
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t3
title: "X-section in AuAu collisions" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: Integrated $D^0$ cross section per nucleon-nucleon collision at mid-rapidity for $p_T &gt;0$ (a) and $p_T &gt;4$ GeV/c (b) as a function of centrality $N_{part}$. The statistical and systematic uncertainties are shown as error bars and brackets on the data points. The green boxes on the data points depict the overall normalization uncertainties in p+p and Au+Au data respectively.
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t4
title: "X-section in pp collisions" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: Integrated $D^0$ cross section per nucleon-nucleon collision at mid-rapidity for $p_T &gt;0$ (a) and $p_T &gt;4$ GeV/c (b) as a function of centrality $N_{part}$. The statistical and systematic uncertainties are shown as error bars and brackets on the data points. The green boxes on the data points depict the overall normalization uncertainties in p+p and Au+Au data respectively.
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t5
title: "RAA" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: $D^0$ $R_{AA}$ in Au+Au collisions at $\sqrt{s_{NN}} =200$ GeV for $0-10\%$ (a), $10-40\%$ (b) and $40-80\%$ (c) centrality bins, respectively. The first two and last two data points are presented as empty circles, indicating that the p+p reference is extrapolated into these $p_T$ ranges. The statistical and systematic uncertainties are shown as error bars and brackets on the data points. The light and dark green boxes on the right depict the normalization uncertainties in determining the $N_{bin}$ in Au+Au collisions and the total inelastic cross section in p+p collisions, respectively.
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t6
title: "$D^0$ and $D^0bar$ spectra" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: $D^0$ and $\bar{D}^0$ invariant yields at mid-rapidity $(|y|&lt;1)$ vs transverse momentum for different centrality classes. Error bars indicate statistical uncertainties and brackets depict systematic uncertainties. Global systematic uncertainties in B.R. and $N_{bin}$ are not plotted. Solid lines depict Levy function fits.
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t7
title: "$D^0bar$/$D^0$ Ratio" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: $\bar{D}^0/D^0$ invariant yield ratio at mid-rapidity $(|y|&lt;1)$ vs transverse momentum for different centrality classes. Error bars indicate statistical uncertainties and brackets depict systematic uncertainties. Dashed lines depict constant function fits to the $\bar{D}^0/D^0$ ratios.
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t8
title: "RCP (60-80%)" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: $D_0$ $R_{CP}$ with the $60-80\%$ spectrum as the reference for different centrality classes compared to the LBT model calculations shown by dashed lines [48, 49].
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.
DOI: 10.17182/hepdata.95750.v1/t10
title: "BW fit parameters for $D^0$" of "Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$"

description: BW fit parameters for $D^0$
description: BNL-RHIC. We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_T &lt; 9$ GeV/c are reported in various centrality bins ($0-10\%$, $10-20\%$, $20-40\%$, $40-60\%$ and $60-80\%$). Blast-Wave thermal models are used to fit the $D^0$-meson $p_T$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi$, $K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi$, $\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_T &gt;4$ GeV/c in central $0-10\%$ Au+Au collisions. At low $p_T$ , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.