Hadronic resonance production and interaction in partonic and hadronic matter in the EPOS3 model with and without the hadronic afterburner UrQMD

We study the production of hadronic resonances and their interaction in the partonic and hadronic medium using the EPOS3 model, which employs the UrQMD model for the description of the hadronic phase. We investigate the centrality dependence of the yields and momentum distributions for various resonances [$\rho {\left(770\right)}^0$, $K^{*}{\left(892\right)}^0$, $\varphi \left(1020\right)$, $\mathrm{\Delta }{\left(1232\right)}^{++}$, $\mathrm{\Sigma }{\left(1385\right)}^{\pm }$, $\mathrm{\Lambda }\left(1520\right)$, $\mathrm{\Xi }{\left(1530\right)}^0$ and their antiparticles] in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. The predictions for $K^{*}{\left(892\right)}^0$ and $\varphi \left(1020\right)$ will be compared with the experimental data from the ALICE collaboration. The observed signal suppression of the $K^{*}{\left(892\right)}^0$ with increasing centrality will be discussed with respect to the resonance interaction in the hadronic medium. The mean transverse momentum and other particle ratios such as $\varphi \left(1020\right)/p$ and $(\mathrm{\Omega }+\overline{\mathrm{\Omega }})/\varphi \left(1020\right)$ will be discussed with respect to additional contributions from the hadronic medium interactions.

Figure 1

Core-corona separation in a semiperipheral (20–40%) Pb-Pb collision at $\sqrt{s_{NN}}=2.76$ TeV.

Figure 2

Core and corona contributions to the $p_{\mathrm{T}}$ spectra of charged hadrons in semiperipheral (20–40%) Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV.

Figure 3

Core and corona contributions to the $p_{\mathrm{T}}$ spectra of charged hadrons in central Pb-Pb collisions.

Figure 4

EPOS3 calculation of the charged-particle multiplicity inside the acceptance of the ALICE VZERO detector ($-3.7<\eta <-1.7$ and $2.8<\eta <5.1$) as a function of impact parameter.

Figure 5

Centrality dependence of the chemical and kinetic freeze-out temperatures of the hadronic phase [28, 29] as a function of centrality via ${\langle d{N}_{\mathrm{ch}}/d\eta \rangle }^{1/3}$.

Figure 6

Centrality dependence of the lifetime of the hadronic phase calculated from the difference in the mean production times of stable hadrons ($\pi ,K,N$, and $\overline{N}$) between the EPOS+UrQMD ON and EPOS+UrQMD OFF scenarios.

Figure 7

Upper panels: transverse momentum distributions of $K^{*}{\left(892\right)}^0+{\overline{K}}^{*}{\left(892\right)}^0$ from EPOS3 with UrQMD OFF and UrQMD ON for Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV in different centrality intervals. These results are compared to measurements from the ALICE Experiment [10] (same data on left and right). The curves are the EPOS3 $p_{\mathrm{T}}$ distributions with fine bins and the shaded bands are the statistical uncertainties of the EPOS3 results. The horizontal lines are the EPOS3 results in the same bins as the ALICE measurements. Lower panels: the ratio of the EPOS3 results to the ALICE measurements as functions of $p_{\mathrm{T}}$ for the different centrality intervals. The shaded bands around unity represent the uncertainties of the measured data.

Figure 8

Upper panels: transverse momentum distributions of $\varphi \left(1020\right)$ from EPOS3 with UrQMD OFF and UrQMD ON for Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV in different centrality intervals. These results are compared to measurements from the ALICE Experiment [10] (same data on left and right). The curves are the EPOS3 $p_{\mathrm{T}}$ distributions with fine bins and the shaded bands are the statistical uncertainties of the EPOS3 results. The horizontal lines are the EPOS3 results in the same bins as the ALICE measurements. Lower panels: the ratio of the EPOS3 results to the ALICE measurements as functions of $p_{\mathrm{T}}$ for four selected centrality intervals. The shaded bands around unity represent the uncertainties of the measured data.

Figure 9

The effect of the UrQMD phase on the $p_{\mathrm{T}}$ spectra of the $K^{*}{\left(892\right)}^0$ and $\varphi \left(1020\right)$ mesons is illustrated by this $p_{\mathrm{T}}$-dependent ratio: the $p_{\mathrm{T}}$ spectra from EPOS3 with UrQMD ON divided by the spectra with UrQMD OFF in different centrality intervals. The shaded bands represent the statistical uncertainties of the ratio.

Figure 10

Mean transverse momentum ($\langle p_{\mathrm{T}}\rangle$) versus hadron mass (resonances in red circles, stable and weakly decaying hadrons in black stars) from EPOS3 with UrQMD OFF (open symbols) and UrQMD ON (filled symbols) for central (0–10%) Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV.

Figure 11

Mean transverse momentum $\langle p_{\mathrm{T}}\rangle$ of (anti)protons and $\varphi \left(1020\right)$ given by EPOS3 for the UrQMD OFF (left panel) and UrQMD ON (right panel) scenarios for multiple centrality intervals. Shaded bands represent the statistical uncertainties. These results are compared to measurements from the ALICE Experiment [10] (same data in both panels); statistical and systematic uncertainties are represented by bars and boxes, respectively. The $\langle p_{\mathrm{T}}\rangle$ values (both theoretical and experimental) are plotted as functions of the mean number of participant nucleons for each centrality class found by the ALICE Collaboration [26].

Figure 12

Ratio of integrated yields $(K^{*}{\left(892\right)}^0+{\overline{K}}^{*}{\left(892\right)}^0)/K^{-}$ (left) and $\varphi \left(1020\right)/K^{-}$ (right) for multiple centrality intervals calculated using EPOS3 with UrQMD OFF and UrQMD ON compared to measurements by the ALICE Experiment [10]. The shaded bands around the EPOS3 curves represent their statistical uncertainties. The bars on the ALICE measurements show the statistical uncertainties. The shaded boxes represent the systematic uncertainties that are uncorrelated between centrality intervals, while the open boxes represent the total systematic uncertainties. The experimental and theoretical data are both plotted as functions of the values of ${\langle d{N}_{\mathrm{ch}}/d\eta \rangle }^{1/3}$ measured by the ALICE experiment [27] at mid rapidity ($\left|\eta \right|<0.5$). For the 90–100% centrality interval (where no measured $\langle d{N}_{\mathrm{ch}}/d\eta \rangle$ values have been reported), the EPOS3 data are plotted at the ${\langle d{N}_{\mathrm{ch}}/d\eta \rangle }^{1/3}$ values found in these simulations.

Figure 13

Ratio of integrated yields $\mathrm{\Sigma }{\left(1385\right)}^{\pm }/\mathrm{\Lambda }$ and $\rho {\left(770\right)}^0/{\pi }^{\pm }$ (left) $\mathrm{\Xi }{\left(1530\right)}^0/{\mathrm{\Xi }}^{-}$, $\mathrm{\Sigma }{\left(1385\right)}^{\pm }/\mathrm{\Lambda }$ and $\mathrm{\Delta }{\left(1232\right)}^{++}/p$ (right) for multiple centrality intervals calculated using EPOS3 with UrQMD ON (numerators and denominators are sums of particles and antiparticles). The shaded bands around the EPOS3 curves represent their statistical uncertainties. The theoretical data are plotted as functions of the values of ${\langle d{N}_{\mathrm{ch}}/d\eta \rangle }^{1/3}$ measured by the ALICE experiment [27] at mid rapidity ($\left|\eta \right|<0.5$).

Figure 14

The $p_{\mathrm{T}}$-dependent (anti)proton/$\varphi \left(1020\right)$ ratio for the 0-10% (left) and 60-80% (right) centrality intervals, calculated using EPOS3 and measured by the ALICE Experiment [10]. For the EPOS3 curves the shaded bands represent the statistical uncertainties. For the ALICE data bars and boxes represent statistical and systematic uncertainties, respectively.

Figure 15

The $p_{\mathrm{T}}$-dependent $(\mathrm{\Omega }+\overline{\mathrm{\Omega }})/\varphi \left(1020\right)$ ratio for the 0–10% centrality interval, calculated using EPOS3 and measured by the ALICE Experiment [10, 35]. For the EPOS3 curves the shaded bands represent the statistical uncertainties. For the ALICE data bars and boxes represent statistical and systematic uncertainties, respectively.

Figure 16

Transverse-momentum spectra from EPOS3 with UrQMD ON (right panels) for the $\rho {\left(770\right)}^0$, $\mathrm{\Delta }{\left(1232\right)}^{++}$, $\mathrm{\Sigma }{\left(1385\right)}^{\pm }$, $\mathrm{\Lambda }\left(1520\right)$, $\mathrm{\Xi }{\left(1530\right)}^0$ (summed with their antiparticles) in different centrality intervals. The shaded bands represent the statistical uncertainties.