Strangeness-neutral equation of state for QCD with a critical point
TL;DR: In this paper, a strangeness-neutral equation of state for QCD was proposed that exhibits critical behavior and matches lattice QCD results for the Taylor-expanded thermodynamic variables up to fourth order in $$\mu _B/T $
Abstract: We present a strangeness-neutral equation of state for QCD that exhibits critical behavior and matches lattice QCD results for the Taylor-expanded thermodynamic variables up to fourth order in $$\mu _B/T$$
. It is compatible with the SMASH hadronic transport approach and has a range of temperatures and baryonic chemical potentials relevant for phase II of the Beam Energy Scan at RHIC. We provide an updated version of the software BES-EoS, which produces an equation of state for QCD that includes a critical point in the 3D Ising model universality class. This new version also includes isentropic trajectories and the critical contribution to the correlation length. Since heavy-ion collisions have zero global net-strangeness density and a fixed ratio of electric charge to baryon number, the BES-EoS is more suitable to describe this system. Comparison with the previous version of the EoS is thoroughly discussed.
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University of North Carolina at Chapel Hill1, University of Nantes2, Ohio State University3, University of Connecticut4, McGill University5, University of Houston6, Indiana University7, Stony Brook University8, Brookhaven National Laboratory9, Lawrence Berkeley National Laboratory10, University of Illinois at Chicago11, North Carolina State University12, University of Illinois at Urbana–Champaign13, University of Washington14, University of Wuppertal15, Michigan State University16, Massachusetts Institute of Technology17, Wayne State University18, University of Minnesota19, University of Chicago20, University of California, Los Angeles21, Chinese Academy of Sciences22
TL;DR: The Beam Energy Scan Theory (BEST) Collaboration was formed with the goal of providing a theoretical framework for analyzing data from the BES program at the relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory as mentioned in this paper.
36 citations
01 Jan 2022
TL;DR: The Beam Energy Scan Theory (BEST) Collaboration was formed with the goal of providing a theoretical framework for analyzing data from the BES program at the relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory as mentioned in this paper .
Abstract: The Beam Energy Scan Theory (BEST) Collaboration was formed with the goal of providing a theoretical framework for analyzing data from the Beam Energy Scan (BES) program at the relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory. The physics goal of the BES program is the search for a conjectured QCD critical point as well as for manifestations of the chiral magnetic effect. We describe progress that has been made over the previous five years. This includes studies of the equation of state and equilibrium susceptibilities, the development of suitable initial state models, progress in constructing a hydrodynamic framework that includes fluctuations and anomalous transport effects, as well as the development of freezeout prescriptions and hadronic transport models. Finally, we address the challenge of integrating these components into a complete analysis framework. This document describes the collective effort of the BEST Collaboration and its collaborators around the world.
36 citations
TL;DR: In this paper , the authors investigated the effects of non-smooth structure in the speed of sound of the matter within neutron stars, such as bumps, spikes, step functions, plateaus, and kinks.
Abstract: The speed of sound of the matter within neutron stars may contain non-smooth structure related to first-order phase transitions or or crossovers. Here we investigate what are the observable consequences of structure, such as bumps, spikes, step functions, plateaus, and kinks. One of the main consequences is the possibility of ultra-heavy neutron stars, i.e.~stars with masses significantly heavier than two solar masses. These stars pass all observational and theoretical constraints, including those imposed by recent LIGO/Virgo gravitational-wave observations and NICER X-ray observations. We thoroughly investigate other consequences of this structure in the speed of sound to develop an understanding of how non-smooth features affect astrophysical observables, such as stellar radii, tidal deformability, moment of inertia, and Love number. Our results have important implications to future gravitational wave and X-ray observations of neutron stars and their impact in nuclear astrophysics.
26 citations
TL;DR: In this article, a relativistically covariant parameterization of dense nuclear matter equation of state is developed for inclusion in computationally demanding hadronic transport simulations, showing that effects due to bulk thermodynamic behavior are reproduced in dynamic hadronic systems.
Abstract: We develop a flexible, relativistically covariant parameterization of dense nuclear matter equation of state suited for inclusion in computationally demanding hadronic transport simulations. Within an implementation in the hadronic transport code SMASH, we show that effects due to bulk thermodynamic behavior are reproduced in dynamic hadronic systems, demonstrating that hadronic transport can be used to study critical behavior in dense nuclear matter, both at and away from equilibrium. We also show that two-particle correlations calculated from hadronic transport simulation data follow theoretical expectations based on the second order cumulant ratio, and constitute a clear signature of crossing the phase diagram above the critical point.
19 citations
DOI•
11 Feb 2022
TL;DR: In this paper , the strangeness-to-baryon ratio was used to calculate a resummed equation of state with lattice QCD simulations at imaginary chemical potentials.
Abstract: We calculate a resummed equation of state with lattice QCD simulations at imaginary chemical potentials. This work presents a generalization of the scheme introduced in 2102.06660 to the case of non-zero $\mu_S$, focusing on the line of strangeness neutrality. We present results up to $\mu_B/T \leq 3.5$ on the strangeness neutral line $\left\langle S \right\rangle = 0$ in the temperature range $130 \rm{MeV} \leq T \leq 280 \rm{MeV}$. We also extrapolate the finite baryon density equation of state to small non-zero values of the strangeness-to-baryon ratio $R=\left\langle S \right\rangle / \left\langle B \right\rangle$. We perform a continuum extrapolation using lattice simulations of the 4stout-improved staggered action with 8, 10, 12 and 16 timeslices.
7 citations
References
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01 Jan 2012
139,059 citations
"Strangeness-neutral equation of sta..." refers methods in this paper
...Other works have already used this new EoS to study out-of-equilibrium approaches to the QCD critical point [44, 45], the sign of the kurtosis [35], and to calculate transport coefficients [46]....
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TL;DR: Finite-size scaling analysis shows that the finite-temperature QCD transition in the hot early Universe was not a real phase transition, but an analytic crossover (involving a rapid change, as opposed to a jump, as the temperature varied).
Abstract: The standard model of particle physics predicts two phase transitions that are relevant for the evolution of the early Universe. One, the quantum chromodynamics transition, involves the strong force that binds quarks into protons and neutrons. Despite much theoretical effort, the nature of this transition remains ambiguous. Now Aoki et al. report computationally demanding calculations that suggest that there was no true phase transition. Instead, an analytic crossover took place, involving a rapid, continuous change with temperature as opposed to a jump. This means that it will be difficult to find experimental evidence of a transition from astronomical observations. The standard model of particle physics predicts two transitions that are relevant for the evolution of the early Universe. Computationally demanding calculations now reveal that a real phase transition did not occur, but rather an analytic crossover, involving a rapid change (as opposed to a jump) as the temperature varies. Quantum chromodynamics (QCD) is the theory of the strong interaction, explaining (for example) the binding of three almost massless quarks into a much heavier proton or neutron—and thus most of the mass of the visible Universe. The standard model of particle physics predicts a QCD-related transition that is relevant for the evolution of the early Universe. At low temperatures, the dominant degrees of freedom are colourless bound states of hadrons (such as protons and pions). However, QCD is asymptotically free, meaning that at high energies or temperatures the interaction gets weaker and weaker1,2, causing hadrons to break up. This behaviour underlies the predicted cosmological transition between the low-temperature hadronic phase and a high-temperature quark–gluon plasma phase (for simplicity, we use the word ‘phase’ to characterize regions with different dominant degrees of freedom). Despite enormous theoretical effort, the nature of this finite-temperature QCD transition (that is, first-order, second-order or analytic crossover) remains ambiguous. Here we determine the nature of the QCD transition using computationally demanding lattice calculations for physical quark masses. Susceptibilities are extrapolated to vanishing lattice spacing for three physical volumes, the smallest and largest of which differ by a factor of five. This ensures that a true transition should result in a dramatic increase of the susceptibilities. No such behaviour is observed: our finite-size scaling analysis shows that the finite-temperature QCD transition in the hot early Universe was not a real phase transition, but an analytic crossover (involving a rapid change, as opposed to a jump, as the temperature varied). As such, it will be difficult to find experimental evidence of this transition from astronomical observations.
1,606 citations
TL;DR: In this article, the 2+1 flavor QCD equation of state has been extended to even finer lattices and now includes ensembles with Nt = 6,8,10,12 up to 16.
947 citations
TL;DR: In this paper, the phase transition restoring chiral symmetry at finite temperatures is considered in a linear σ-sigma model. But the model is not suitable for the case of massless flavors.
Abstract: The phase transition restoring chiral symmetry at finite temperatures is considered in a linear $\ensuremath{\sigma}$ model. For three or more massless flavors, the perturbative $\ensuremath{\epsilon}$ expansion predicts the phase transition is of first order. At high temperatures, the ${\mathrm{U}}_{A}(1)$ symmetry will also be effectively restored.
897 citations
University of Iowa1, Los Alamos National Laboratory2, University of Utah3, Central China Normal University4, Indiana University5, American Physical Society6, Bielefeld University7, Brookhaven National Laboratory8, Lawrence Livermore National Laboratory9, University of Regensburg10, University of California, Santa Barbara11
TL;DR: In this paper, the authors present results for the equation of state in ($2+1$)-flavor QCD using the highly improved staggered quark action and lattices with temporal extent.
Abstract: We present results for the equation of state in ($2+1$)-flavor QCD using the highly improved staggered quark action and lattices with temporal extent ${N}_{\ensuremath{\tau}}=6$, 8, 10, and 12. We show that these data can be reliably extrapolated to the continuum limit and obtain a number of thermodynamic quantities and the speed of sound in the temperature range 130--400 MeV. We compare our results with previous calculations and provide an analytic parameterization of the pressure, from which other thermodynamic quantities can be calculated, for use in phenomenology. We show that the energy density in the crossover region, $145\text{ }\text{ }\mathrm{MeV}\ensuremath{\le}T\ensuremath{\le}163\text{ }\text{ }\mathrm{MeV}$, defined by the chiral transition, is ${\ensuremath{\epsilon}}_{c}=(0.18--0.5)\text{ }\text{ }\mathrm{GeV}/{\mathrm{fm}}^{3}$, i.e., $(1.2--3.1)\text{ }{\ensuremath{\epsilon}}_{\text{nuclear}}$. At high temperatures, we compare our results with resummed and dimensionally reduced perturbation theory calculations. As a byproduct of our analyses, we obtain the values of the scale parameters ${r}_{0}$ from the static quark potential and ${w}_{0}$ from the gradient flow.
885 citations