Balance of attractive and repulsive hadronic interactions: The influence of hadronic spectrum and excluded-volume effects on lattice thermodynamics, and consequences for experiments

Repulsive hadronic interactions play a relevant role in QCD dynamics, attractive ones being represented by resonance formation. In this study we propose different schemes in order to parameterize repulsive interactions, thus being able to extract effective sizes of hadrons from fits to lattice QCD simulations. We find that allowing a difference between the strange and light sectors, strange particles are systematically smaller than light ones with equal mass. The very simple implementation of repulsive interactions would in principle allow us to extract precise information about all hadronic species once corresponding lattice observables, sensitive to the species of interest, are provided. With the parametrization which best reproduces lattice data there is also a good description of experimental yields measured by the ALICE and STAR experiments.

Figure 1

Lattice data for ${\mu }_S/{\mu }_B{|}_{LO}$ [42] (top panel), ${\chi }_4^S/{\chi }_2^S$ [41] (middle panel), and ${\chi }_4^B/{\chi }_2^B$ [2] (bottom panel) in comparison to HRG calculations with PDG2016 and QM lists in the ideal scheme (solid blue and dashed red curves) and with the QM list in the EV-HRG with the corresponding parametrization listed in Table 6 (dotted green curves).

Figure 2

Lattice data for ${\chi }_{31}^{BS}/{\chi }_{11}^{BS}$ (top left panel), ${\chi }_{31}^{BQ}/{\chi }_{11}^{BQ}$ (top right panel), and ${\chi }_6^B/{\chi }_2^B$ (bottom left panel) [2, 43, 44] in comparison to HRG calculations with PDG2016 and QM lists in the ideal scheme (solid blue and dashed red lines) and with QM list plus the corresponding EV effects listed in Table 6 with errors (dashed green area). Predictions for ${\chi }_8^B/{\chi }_2^B$ (bottom right panel) are shown. The lattice data here shown are not considered for the fits.

Figure 3

Lattice data for ${\chi }_{11}^{BQ}/{\chi }_2^B$ (left panel) [2, 45] in comparison to HRG calculations with PDG2016 and QM lists in the ideal scheme (solid blue and dashed red curves) and with QM list in the EV-HRG and Cross-HRG with the corresponding parametrization listed in Table 6 (dotted green and dot-dashed black curves). Predictions for ${\chi }_4^Q/{\chi }_2^Q$ (right panel) are shown. The lattice data here shown are not considered for the fits.