Surprisingly large uncertainties in temperature extraction from thermal fits to hadron yield data at LHC

Abstract

The conventional hadron-resonance gas (HRG) model with the Particle Data Group (PDG) hadron input, full chemical equilibrium, and the hadron type dependent eigenvolume interactions is employed to fit the hadron mid-rapidity yield data of ALICE Collaboration for the most central Pb+Pb collisions. For the case of point-like hadrons the well-known fit result $T=154\pm 2$ MeV is reproduced. However, the situation changes if hadrons have different eigenvolumes. In the case when all mesons are point-like while all baryons have an effective hard-core radius of 0.3 fm the ${\chi }^2$ temperature dependence of the ${\chi }^2$ has a broad minimum in the temperature range of $155-210$ MeV, with fit quality comparable to the $T\sim 155$ MeV minimum in the point-particle case. Very similar result is obtained when only baryon-baryon eigenvolume interactions are considered, with eigenvolume parameter taken from previous fit to ground state of nuclear matter. Finally, when we apply the eigenvolume corrections with mass-proportional eigenvolume $v_i\sim m_i$, fixed to particular proton hard-core radius $r_p$, we observe a second minimum in the temperature dependence of the ${\chi }^2$, located at the significantly higher temperatures. For instance, at $r_p=0.5$ fm the fit quality is better than in the point-particle HRG case in a very wide temperature range of $170-320$ MeV, which gives an uncertainty in the temperature determination from the fit to the data of 150 MeV. These results show that thermal fits to the heavy-ion hadron yield data are very sensitive to the modeling of the short-range repulsion eigenvolume between hadrons, and that chemical freeze-out temperature can be extracted from the LHC hadron yield data only with sizable uncertainty.

8 pages, 3 figures, v3: added calculations for baryon-baryon only eigenvolume interactions fitted to nuclear ground state, added table with fitted data, title and discussion modified in order to ensure more clarity about the presented results

References in corpus (16)

• From controversy to precision on the sigma meson: a review on the status of the non-ordinary $f_0(500)$ resonance
• K*(892)${}^0$ and $\Phi$(1020) production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Hadron yields and the phase diagram of strongly interacting matter
• Matching Excluded Volume Hadron Resonance Gas Models and Perturbative QCD to Lattice Calculations
• Non-thermal p/pi ratio at LHC as a consequence of hadronic final state interactions
• Van der Waals Equation of State with Fermi Statistics for Nuclear Matter
• Centrality dependence of hadronization and chemical freeze-out conditions in heavy ion collisions at \sqrt s_{NN} = 2.76 TeV
• Hadron Resonance Gas Equation of State from Lattice QCD
• Simple Solution to the Strangeness Horn Description Puzzle
• New scenarios for hard-core interactions in a hadron resonance gas
• Transverse-momentum spectra of strange particles produced in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV in the chemical non-equilibrium model
• Understanding the $p/\pi$ ratio at LHC due to QCD mass spectrum
• Equation of state and sound velocity of hadronic gas with hard-core interaction
• QCD over $T_c$: hadrons, partons and continuum
• Entropy production in chemically non-equilibrium quark-gluon plasma created in central Pb+Pb collisions at LHC energies
• Analysis of hadron yield data within hadron resonance gas model with multi-component eigenvolume corrections

Cited by in corpus (26)

• van der Waals Interactions in Hadron Resonance Gas: From Nuclear Matter to Lattice QCD
• Thermal-FIST: A package for heavy-ion collisions and hadronic equation of state
• Multiplicity dependence of light nuclei production at LHC energies in the canonical statistical model
• Higher-order baryon number susceptibilities: interplay between the chiral and the nuclear liquid-gas transitions
• Finite resonance widths influence the thermal-model description of hadron yields
• Examination of the sensitivity of the thermal fits to heavy-ion hadron yield data to the modeling of the eigenvolume interactions
• Kinetic freeze-out temperature from yields of short-lived resonances
• Chemical freeze-out conditions and fluctuations of conserved charges in heavy-ion collisions within quantum van der Waals model
• Flavor-dependent eigenvolume interactions in a hadron resonance gas
• Critical point of nuclear matter and beam energy dependence of net proton number fluctuations
• Repulsive interactions and their effects on the thermodynamics of hadron gas
• Beth-Uhlenbeck approach for repulsive interactions between baryons in a hadron gas
• Excluded-volume effects for a hadron gas in Yang-Mills theory
• Hadron resonance gas with van der Waals interactions
• Centrality dependence of chemical freeze-out parameters from net-proton and net-charge fluctuations using hadron resonance gas model
• Monte Carlo approach to the excluded-volume hadron resonance gas in grand canonical and canonical ensembles
• Ambiguities in the hadro-chemical freeze-out of Au+Au collisions at SIS18 energies and how to resolve them
• Statistical hadron-gas treatment of systems created in proton-proton interactions at CERN SPS
• Light nuclei in the hadron resonance gas
• Chemical freeze-out curve in heavy-ion collisions and the QCD critical point
• Second virial coefficients of light nuclear clusters and their chemical freeze-out in nuclear collisions
• Thermodynamic Geometry of Strongly Interacting Matter
• A hadron-quark hybrid model reliable for the EoS in ${\mu }_B\le 400$ MeV
• Shear viscosity from perturbative Quantum Chromodynamics to the hadron resonance gas at finite baryon, strangeness, and electric charge densities
• Universal descriptions of chemical freeze-out based on pressure and specific heat
• Role of repulsive interactions in the interplay with missing strange resonances