Phase Diagram Of Nuclear Matter Research Articles

Use of the Meta-Analysis and Kolmogorov Criteria in the Finding of Singularities of a Nuclear Matter Created in Ultra-Relativistic Nuclear Collisions

Published theoretical data from several models – PHSD/HSD both with and without chiral symmetry restoration (CSR), applied to experimental data on nuclear collisions from BEVALAC/SIS to LHC energies were analyzed using meta-analysis and Kolmogorov criteria. This made it possible to localize possible features of nuclear matter created in central nucleus-nucleus collisions. Ignition of a drop of quark-gluon plasma (QGP) begins already at an energy of about √s<SUB>NN</SUB> = 2 GeV. The assessment showed that this QGP droplet occupies a small fraction, 15% (average radius of about 5.3 fm, if the fireball radius is 10 fm), of the total volume of the fireball created at √s<SUB>NN</SUB> = 2.7 GeV. A drop of exotic matter undergoes a split phase transition – separated boundaries of sharp (1<sup>st</sup> order) crossover and CSR in chiral limit, between QGP and Quarkyonic matter at an energy about √s<SUB>NN</SUB> = 3.5 GeV. The critical endpoint of 2<sup>nd</sup> order probably cannot be reached in nuclear collisions. The triple phase area occupies interval from √s<SUB>NN</SUB> =12 GeV to 15 GeV, the critical endpoint of 1<sup>st</sup> order – at around √s<SUB>NN</SUB> = 20 GeV. The boundary of smooth (2<sup>nd</sup> order) crossover transition with CSR in chiral limit between Quarkyonic matter and QGP was localized between √s<SUB>NN</SUB> = 9.3 GeV and 12 GeV, and between Hadronic and QGP in the interval from √s<SUB>NN</SUB> = 15 GeV to 20 GeV, the boundary of sharp (1<sup>st</sup> order) crossover transition with CSR in chiral limit between Hadronic matter and QGP was localized after √s<SUB>NN</SUB> = 20 GeV. The phase trajectory of the hadronic corona, enveloping the exotic droplet, always remains in the hadronic phase. The possible phase diagram of nuclear matter created in mid-central heavy ion collisions is also presented in the same energy range as for central collisions. Taking into account the quantum nature of the fireball created in nuclear collisions, emphasis is on the existence of events in central nuclear collisions at energy range from √s<SUB>NN</SUB> = 2 GeV to 2.76 TeV, at which no exotic matter is created and nuclear matter in the fireball remains in the hadronic phase throughout its (fireball) evolution.

Phase diagram determination at fivefold nuclear compression

In the standard model of particle physics, the strong force is characterized by the theory of quantum chromodynamics (QCD). It is commonly understood from QCD properties that hadrons, at sufficiently high temperatures or densities, melt into their constituent quarks, thereby undergoing a deconfinement transition to a new phase of quarks and gluons, often referred to as quark matter or quark-gluon plasma (QGP) [1,2]. Although QGP has been observed in relativistic heavy-ion collisions [3,4], uncertainties remain about when the onset of deconfinement occurs. After comparing simulations from a reliable hadron and quark relativistic transport model with recent data from the STAR experiment, we determined that the onset of the hadron-quark phase transition occurs at about five times nuclear compression, corresponding to temperature T∼ 112 MeV and baryon chemical potential μB∼ 586 MeV, in the nuclear matter phase diagram. This discovery has significant implications for the studies of both the early and present universe [5], including the fraction of dark matter formed in the early universe [6–8] and the structure and dynamics of neutron stars and their mergers [9].

Preface: CSQCDIX

The 9th international workshop Compact Stars in the QCD phase diagram was held, during August 1-5 2022, in Banff (Alberta, Canada) entitled “Compact Stars in the QCD phase diagram IX (CSQCD IX): From RHIC to Astrophysics, Probing the Quark-Gluon Plasma”. This series of meetings started in 2001 in Copenhagen (Denmark), and then continued in 2009 in Beijing (China), 2012 in Guaruja (Brazil), 2014 in Prerow (Germany), 2016 in l’Aquila (Italy), 2017 in Dubna (Russia), 2018 in New York (NY, USA), and 2020 at ICTS (India; on line).The CSQCD workshops aim to bring together physicists working on strongly interacting dense matter with astrophysicists working on Compact Stars and related astrophysical phenomena such as supernovae, gamma ray bursts and pulsars. A profound theoretical description of these astrophysical phenomena necessarily involves the equation of state and transport properties of QCD matter that are derived from non-perturbative quantum field theories, many-body physics of strongly interacting matter and phenomenological investigations. CSQCD IX focussed on recent explorations of the quark-gluon phase using colliders (e.g. RHIC and LHC) and on the renewed interest in neutron and quark matter in astrophysics, particularly in the gravitational wave era.The science sessions focused on nuclear matter at high baryon density, on probing neutron-star matter in the laboratory, and on explorations of characterization of the critical endpoint in the nuclear matter phase diagram. The phases and the equation of state was discussed (in memory of Stefan Schramm) as well as transport phenomena in compact stars. Recent results constraining the nuclear symmetry energy from experiments, theory and observations and implications for compact stars were also presented. For the first time in the CSQCD series, talks highlighted the importance of gravitational waves as: (i) a tool to probe compact stars and QCD phase transitions; (ii) as probes of reacting interfaces in the core of neutron stars. Also featured were recent data from NICER and implications on neutron stars as well as neutron star mergers as materials science.The present volume of the Journal of Physics: Conference Series represents selected contributions from the participants of the CSQCD IX workshop. Each submitted contribution has been peer reviewed and the Editors are very grateful to the referees for their careful support.The Editors of the CSQCD IX Proceedings:Rachid Ouyed (University of Calgary, Canada)Denis Leahy (University of Calgary, Canada)Nico Koning (University of Calgary, Canada)Tobias Fischer (University of Wroclaw, Poland)Sumiyoshi Kohsuke (National Institute of Technology, Numazu College, Japan)Massimo Mannarelli (National Laboratories of Gran Sasso, Italy)Fridolin Weber (San Diego State University, USA)Calgary, 1st of May 2023

Preface

These are the proceedings of the 36th edition of the Winter Workshop on Nuclear Dynamics, which was held In Puerto Vallarta, Mexico, in March 2020. Our meeting was the final in-person gathering in our field before the international lockdown period due to Covid-19. As in previous years the unique character of this conference series has allowed us to bring scientists from various fields of nuclear physics together to discuss their scientific achievements.At the high-energy frontier very exciting results not only from the heavy-ion collisions but also smaller systems at the LHC were shown. At this time the LHC experiments are upgrading their detectors for the third large run period, which is scheduled to start in early 2022. Several talks focused on the future experimental program at the LHC. At the lower energies the second RHIC beam energy scan is underway to span the gap between the SPS and RHIC and search for critical phenomena in the nuclear matter phase diagram. This program is complemented by spin and small systems measurements at the highest RHIC energies. The future programs of sPHENIX and the planned electron-ion collider (EIC) were represented as well.Theory progress has been made across all these different energy and system size regimes, and the new data, in particular from the LHC and RHIC, are motivating more detailed modeling and a deeper understanding of the underlying physics.These proceedings of the 36th Winter Workshop on Nuclear Dynamics again provide a snapshot of the status of the field. The articles, many of which are written by some of the most promising young scientists in the field, are conveying the present excitement that permeates all subfields of nuclear science.All papers published in this volume have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.Rene Bellwied (University of Houston, USA)John Harris (Yale University, USA)Claudia Ratti (University of Houston, USA)Anthony Timmins (University of Houston, USA)

ArXiv : Heavy-ion physics: freedom to do hot, dense, exciting QCD

In these two lectures I review the basics of heavy-ion collisions at relativistic energies and the physics we can do with them. I aim to cover the basics on the kinematics and observables in heavy-ion collider experiments, the basics on the phenomenology of the nuclear matter phase diagram, some of the model building and simulations currently used in the heavy-ion physics community and a selected list of amazing phenomenological discoveries and predictions.

Prospects for Studying Hyperons and Hypernuclei on the NICA Collider

NICA is a new flagship project in Dubna aimed at constructing a new accelerator complex for heavy ions. The main goal of the project is experimental exploration of the still poorly known region of the nuclear matter phase diagram of the highest net-baryon density. The MPD detector is a multi-purpose large acceptance spectrometer for studying heavy-ion collisions. An overview is presented of the NICA physics program for studying strangeness production and present MPD performance for reconstructing hyperons and hypernuclei.

Critical parameters of the liquid-gas phase transition in thermal symmetric and asymmetric nuclear matter

The properties of critical parameters and phase diagram structure of liquid-gas phase transition are investigated in thermal symmetric and asymmetric nuclear matter with the covariant density functional (CDF) theory. Although uncertainty remains in predicting the critical parameters such as the critical temperature and pressure from various CDF functionals, several correlations are explored numerically and verified to be approximately linear between them. These correlations become worse when nuclear matter is more isospin asymmetric, resulting mainly from the effects induced by symmetry energy. By looking over the isospin dependence of the critical temperature, the role of the symmetry energy in LG transition properties of asymmetric matter is realized. The change of critical temperature with isospin asymmetry is found to be correlated well with and as a consequence could be constrained by the density slope of symmetry energy at saturation density. Then, the structure of phase diagram of thermal nuclear matter is analyzed carefully. It is revealed that the contribution from symmetry energy dominates the size of liquid-gas phase coexistence area. Moreover, the specific pattern of the phase diagram could be determined by the critical temperature at non-zero isospin asymmetry, illustrated from the correlations of the temperature with pressures at several characteristic points, paving the possible way to further explore the structure of liquid-gas phase diagram of thermal nuclear matter.

Isospin-dependent phase diagram of nuclear matter

In this article we obtain the phase diagram of nuclear matter extending it from the traditional two-dimensional density-temperature plane to three-dimensional space of density, temperature, and isospin asymmetry. We identify the liquid-gas coexistence region by means of Maxwell constructions over pressure-volume isotherms. Such pressure-density equations of state were constructed from data obtained from interpolating results from molecular dynamics simulations of infinite nuclear systems in the liquid phase those of Fermi gases at low (sub-saturation) densities. The molecular dynamics results were used to obtain the energy per nucleon and pressure for systems with densities and temperatures in the ranges ρ=0.01 to 0.2 fm−3, T between 1 and 15 MeV, and with isospin content of x = Z/A = 0.3, 0.35, 0.4, 0.45 and 0.5. The results indicate that symmetric and asymmetric matter are self-bound and show a coexistence region that extends, approximately, to densities of up to ρ0/2, temperatures of up to 16 MeV, and down to proton fractions of 13%.

Study on cosmic test and QC method of high-rate MRPC for CBM-TOF

The CBM (Compressed Baryonic Matter) experiment constructed at FAIR (Facility for Anti-proton and Ion Research) at GSI, Darmstadt, Germany, will provide unique research opportunities to explore the phase diagram of nuclear matter. As one of the core detectors in the CBM experiment, the Time-of-Flight (TOF) system applies the MRPC (Multi-gap Resistive Plate Chamber) for a precise particle identification for all the incident charged hadrons. The CBM-TOF will be operated at an ion beam intensity up to 109/s, which means the particle fluxes on the TOF wall can reach an unprecedentedly high rate of 30 kHz/cm2. Almost half of the MRPC counters are from the inner region of the TOF wall, and they will be assembled with the low-resistive glass which enables them to work under such high rate. This is the first time of the large scale application of the low-resistive glass MRPCs into the nuclear and high-energy physics experiments. It is especially important to study on the production and test procedure to keep the good performance of all these counters. For this mass production, we have developed a set of specified manufacturing procedure and quality control method to guarantee the performance of all the counters. A newly developed method to check the uniformity of the gas gap with help of the projection imaging technique has been first applied. Until now, 73 MRPCs have been produced for the eTOF project in the BESII detector upgrade at STAR and the TOF system of mini-CBM. Tested by cosmic ray in a system based on TRB, all the produced counters show a stable performance of above 95% efficiency and below 90 ps time resolution. The study on the mass production of the low-resistive plate chamber will provide experience for wide application of MRPC into the high rate experiments in the future. In this paper, the counter design, manufacturing procedures, quality control methods and test results for this MRPC counter are described in a detailed way.

Dense cold matter

Opportunities to study unexplored domains of nuclear matter phase diagram with BM@N and SPD-NICA is discussed. Since the optimal initial energy range depends on the phase diagram domain, the subject and experimental methods for its study have a lot of opportunities both for the fixed target and collider experiments. Fixed target experiments provide an access to the laboratory study of nuclear matter with the unprecedented density as high as the one for the neutron star core and even larger. A specialised kinematic trigger for relativistic ion-ion collisions can be used for this study. On the other hand, the NICA collider energy range will provide unique opportunities to study interactions between multi-quark states. The article discusses the importance of experimental study of the diquark component of nuclear structure function and diquark-diquark interactions. It is important to develop neutron identification methods both for the fixed target and collider experiments.

34th Winter Workshop on Nuclear Dynamics

PREFACEThese are the proceedings of the 34th edition of the Winter Workshop on Nuclear Dynamics, which was held on the Caribbean island of Guadeloupe. As in previous years the unique character of this conference series has allowed us to bring scientists from various fields of nuclear physics together to discuss their scientific achievements.At the high-energy frontier very exciting results not only from the heavy-ion collisions but also smaller systems at the LHC were shown. At the lower energies the RHIC beam energy scan is underway to span the gap between the SPS and RHIC and search for critical phenomena in the nuclear matter phase diagram. This program is complemented by spin and small systems measurements at the highest RHIC energies. The future programs of sPHENIX and the planned electron-ion collider (EIC) were represented as well.

Toward electrodynamics of unconventional phases of dilute nuclear matter

The phase diagram of isospin-asymmetrical nuclear matter may feature a number of unconventional phases, which include the translationally and rotationally symmetric, but isospin-asymmetrical BCS condensate, the current-carrying Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase, and the heterogeneous phase-separated phase. Because the Cooper pairs of the condensate carry a single unit of charge, these phases are charged superconductors and respond to electromagnetic gauge fields by either forming domains (type-I superconductivity) or quantum vortices (type-II superconductivity). We evaluate the Ginzburg-Landau (GL) parameter across the phase diagram and find that the unconventional phases of isospin-asymmetrical nuclear matter are good type-II superconductors and should form Abrikosov vortices with twice the quantum of magnetic flux. We also find that the LOFF phase at the boundary of the transition to the type-I state, with the GL parameter being close to the critical value .

The Search for Critical Behavior and Other Features of the QCD Phase Diagram – Current Status and Future Prospects

I briefly review the current experimental status of the search for evidence of a Critical Point and other features in the phase diagram of nuclear matter. I then present the future prospects for turning these trends and suggestive features into definitive conclusions.

From real clusters to experimental nuclear matter phase diagram

We have determined the critical properties of infinite uncharged nuclear matter based on cluster emission data. To do this, three obstacles had to be overcome: finite size effects, the Coulomb interaction and appropriate physical picture (not particles coexisting in a box). That lead to the complete liquid to vapor phase diagram of neutral, symmetric, uncharged nuclear matter.

Track reconstruction and particle identification developments for a study of event-by-event fluctuations in heavy ion collisions at NICA

A Monte Carlo simulation of heavy ion collisions (Au+Au) has been performed at MPD (Multi Purpose Detector) at NICA (Dubna) for a study of the possible critical point in the phase diagram of the hot nuclear matter. The simulation took into account real detector effects with as many details as possible to properly describe the apparatus response. Particle identification (PID) has been tuned to account for modifications in track reconstruction. Some results on hadron identification in the TPC and TOF (Time Of Flight) detectors with realistically simulated response have been also obtained.

Effects of Induced Surface Tension in Nuclear and Hadron Matter

Short range particle repulsion is rather important property of the hadronic and nuclear matter equations of state. We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard-core repulsion. In addition to the hard-core repulsion taken into account by the proper volumes of particles, this equation of state explicitly contains the surface tension which is induced by another part of the hard-core repulsion between particles. At high densities the induced surface tension vanishes and the excluded volume treatment of hard-core repulsion is switched to its proper volume treatment. Possible applications of this equation of state to a description of hadronic multiplicities measured in A+A collisions, to an investigation of the nuclear matter phase diagram properties and to the neutron star interior modeling are discussed.

Nuclear and hadron matter equation of state within the induced surface tension approach

We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard core repulsion. The suggested equation of state explicitly contains the surface tension which is induced by particle interaction. At high densities such a surface tension vanishes and in this way it switches the excluded volume treatment of hard core repulsion to its eigen volume treatment. The great advantage of the developed model is that the number of equations to be solved is two and it does not depend on the number of independent hard-core radii. Using the suggested equation of state we obtained a high quality fit of the hadron multiplicities measured at AGS, SPS, RHIC and ALICE energies and studied the properties of the nuclear matter phase diagram. It is shown the developed equation of state is softer than the gas of hard spheres and remains causal up to the several normal nuclear densities. Therefore, it could be applied to the neutron star interior modeling.

Indications for a critical point in the phase diagram for hot and dense nuclear matter

Two-pion interferometry measurements are studied for a broad range of collision centralities in Au+Au (sNN=7.7–200 GeV) and Pb+Pb (sNN=2.76 TeV) collisions. They indicate non-monotonic excitation functions for the Gaussian emission source radii difference (Rout−Rside), suggestive of reaction trajectories which spend a fair amount of time near a soft point in the equation of state (EOS) that coincides with the critical end point (CEP). A Finite-Size Scaling (FSS) analysis of these excitation functions, provides further validation tests for the CEP. It also indicates a second order phase transition at the CEP, and the values Tcep∼165 MeV and μBcep∼95 MeV for its location in the (T,μB)-plane of the phase diagram. The static critical exponents (ν≈0.66 and γ≈1.2) extracted via the same FSS analysis, place this CEP in the 3D Ising model (static) universality class. A Dynamic Finite-Size Scaling analysis of the excitation functions, gives the estimate z∼0.87 for the dynamic critical exponent, suggesting that the associated critical expansion dynamics is dominated by the hydrodynamic sound mode.

Feasibility study of heavy ion physics program at NICA

There are strong experimental and theoretical evidences that in collisions of heavy ions at relativistic energies nuclear matter undergoes a phase transition to the deconfined state—Quark Gluon Plasma. The caused energy region of such transition was not found at high energy at SPS and RHIC and search for this energy is shifted to lower energies, which will be covered by the future NICA (Dubna), FAIR (Darmstadt) facilities and BES II at RHIC. Fixed target and collider experiments at the NICA facility will work at the energy range from a few AGeV up to \(\sqrt {\;{S_{NN}}} \; = \;11\;GeV\) GeV and will study the most interesting area on the nuclear matter phase diagram. The most remarkable results were observed in the study of collective phenomena occurring in the early stage of nuclear collisions. Investigation of the collective flow will provide information on Equation of State (EoS) for nuclear matter. Study of the Event-by-Event fluctuations and correlations can give us signals of critical behavior of the system. Femtoscopy analysis provides the space-time history of the collisions. Also, it was found that baryon stopping power revealing itself as a “wiggle” in excitation function of curvature of the (net)proton rapidity spectrum relates to the order of the phase transition. The available observations of an enhancement of dilepton rates at low invariant masses may serve as a signal of the chiral symmetry restoration in hot and dense matter. Due to this fact, measurements of the dilepton spectra are considered to be an important part of the NICA physics program. The study of strange particles and hypernuclei production gives additional information on the EoS and “strange” axis of the QCD phase diagram. In this paper a feasibility of the considered investigations is shown by the detailed Monte Carlo simulations applied to the planned experiments (BM@N, MPD) at NICA.

Indications for a critical end point in the phase diagram for hot and dense nuclear matter.

Excitation functions for the Gaussian emission source radii difference (R_{out}^{2}-R_{side}^{2}) obtained from two-pion interferometry measurements in Au+Au (sqrt[s_{NN}]=7.7-200 GeV) and Pb+Pb (sqrt[s_{NN}]=2.76 TeV) collisions are studied for a broad range of collision centralities. The observed nonmonotonic excitation functions validate the finite-size scaling patterns expected for the deconfinement phase transition and the critical end point (CEP), in the temperature versus baryon chemical potential (T,μ_{B}) plane of the nuclear matter phase diagram. A finite-size scaling (FSS) analysis of these data suggests a second order phase transition with the estimates T^{cep}∼165 MeV and μ_{B}^{cep}∼95 MeV for the location of the critical end point. The critical exponents (ν≈0.66 and γ≈1.2) extracted via the same FSS analysis place this CEP in the 3D Ising model universality class.