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Parotto, Paolo

Publications and source records attributed to Parotto, Paolo.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Finite density QCD equation of state: Critical point and lattice-based ๐‘‡โ€ฒ expansion

Here, we present a novel construction of the QCD equation of state (EoS) at finite baryon density. Our work combines a recently proposed resummation scheme for lattice QCD results with the universal critical behavior at the QCD critical point. This allows us to obtain a family of equations of state in the range 0 โ‰ค ๐œ‡ ๐ต โ‰ค 700 MeV and 25 MeV โ‰ค ๐‘‡ โ‰ค 800 MeV, which match lattice QCD results near ๐œ‡ ๐ต =0 while featuring a critical point in the 3D Ising model universality class. The position of the critical point can be chosen within the range accessible to beam-energy scan heavy-ion collision experiments. The strength of the singularity and the shape of the critical region are parametrized using a standard parameter set. We impose stability and causality constraints and discuss the available ranges of critical point parameter choices, finding that they extend beyond earlier parametric QCD EoS proposals. We present thermodynamic observables, including baryon density, pressure, entropy density, energy density, baryon susceptibility and speed of sound, that cover a wide range in the QCD phase diagram relevant for experimental exploration.

Astronomy & Astrophysicsโ†—
DOE OSTI2022

Critical lensing and kurtosis near a critical point in the QCD phase diagram in and out of equilibrium

In this work, we study the lensing effect of the QCD critical point on hydrodynamic trajectories and its consequences on the net-proton kurtosis $\kappa$ 4 . Including critical behavior by means of the BEST Collaboration equation of state (EoS), we first consider a scenario in equilibrium, then compare with hydrodynamic 0+1โขD simulations with Bjorken expansion, including both shear and bulk viscous terms. Here, we find that, both in and out of equilibrium, the size and shape of the critical region directly affect if the signal will survive through the dynamical evolution.

73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ†—
DOE OSTI2022

Off-of-equilibrium effects on Kurtosis Along Strangeness-Neutral Trajectories

The Beam Energy Scan program at the Relativistic Heavy Ion Collider (RHIC) is searching for the QCD critical point. The main signal for the critical point is the kurtosis of the distribution of proton yields obtained on an event by event basis where one expects a peak at the critical point. However, its exact behavior is still an open question due to out-of-equilibrium effects and uncertainty in the equation of state. Here we use a simplistic hydrodynamic model that enforces strangeness-neutrality, selecting trajectories that pass close to the critical point. We vary the initial conditions to estimate the effect of out-of-equilibrium hydrodynamics on the kurtosis signal.

73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ†—
DOE OSTI2022

Thermal-model-based characterization of heavy-ion-collision systems at chemical freeze-out

We investigate the chemical freeze-out in heavy-ion collisions (HICs) and the impact of the hadronic spectrum on thermal model analyses [1, 2]. Detailed knowledge of the hadronic spectrum is still an open question, which has phenomenological consequences on the study of HICs. By varying the number of resonances included in Hadron Resonance Gas (HRG) Model calculations, we can shed light on which particles may be produced. Furthermore, we study the influence of the number of states on the so-called two flavor freezeout scenario, in which strange and light particles can freeze-out separately. We consider results for the chemical freeze-out parameters obtained from thermal model fits and from calculating net-particle fluctuations. We will show the effect of using one global temperature to fit all particles and alternatively, allowing particles with and without strange quarks to freeze-out separately.

73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ†—
DOE OSTI2020

Chemical freeze-out parameters of net-kaons in heavy-ion collisions

In this work, we study chemical freeze-out parameters for heavy-ion collisions by performing two different thermal analyses. We analyze results from thermal fits for particle yields, as well as, net-charge fluctuations in order to characterize the chemical freeze-out. The Hadron Resonance Gas (HRG) model is employed for both methods. By separating the light hadrons from the strange hadrons in thermal fits, we study the proposed flavor hierarchy. For the net-charge fluctuations, we calculate the mean-over-variance ratio of the net-kaon fluctuations in the HRG model at the five highest energies of the RHIC Beam Energy Scan (BES) for different particle data lists. We compare these results with recent experimental data from the STAR collaboration in order to extract sets of chemical freeze-out parameters for each list. We focused on particle lists which differ largely in the number of resonant states. By doing so, our analysis determines the effect of the amount of resonances included in the HRG model on the freeze-out conditions. Our findings have potential impact on various other models in the field of relativistic heavy ion collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ†—
DOE OSTI2020

Cross-Correlators of Conserved Charges in QCD

We present cross-correlators of QCD conserved charges at ยต B = 0 from lattice simulations and perform a Hadron Resonance Gas (HRG) model analysis to break down the hadronic contributions to these correlators. We construct a suitable hadronic proxy for the ratio โ€“ฯ‡$^{BS}_{11}$ /ฯ‡$^{S}_{2}$ and discuss the dependence on the chemical potential and experimental cuts. Furthermore, we then perform a comparison to preliminary STAR results and comment on a possible direct comparison of lattice and experiment

73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ†—
DOE OSTI2020

Determination of Chemical Freeze-Out Parameters from Net-Kaon Fluctuations at RHIC

We calculate the mean-over-variance ratio of the net-kaon fluctuations in the Hadron Resonance Gas (HRG) Model for the five highest energies of the RHIC Beam Energy Scan (BES) for different particle data lists. We compare these results with the latest experimental data from the STAR collaboration in order to extract sets of chemical freeze-out parameters for each list. We focused on the PDG2012 and PDG2016+ particle lists, which differ largely in the number of resonant states. Furthermore, our analysis determines the effect of the amount of resonances included in the HRG on the freeze-out conditions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ†—