scholarly journals Transport Model Approach to Λ and Λ¯ Polarization in Heavy-Ion Collisions

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1852
Author(s):  
Larissa V. Bravina ◽  
Kyrill A. Bugaev ◽  
Oleksandr Vitiuk ◽  
Evgeny E. Zabrodin
Keyword(s):  
Nuclear Matter ◽  
Heavy Ion Collisions ◽  
Transport Model ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Baryon Density ◽  
Dense Medium ◽  
Interaction Point ◽  
Ion Collisions ◽  
Dense Nuclear Matter

This paper investigates the symmetry breaking between the polarizations of Λ and Λ¯ hyperons in relativistic collisions of heavy ions at intermediate and low energies. The microscopic transport model UrQMD is employed to study the thermal vorticity of hot and dense nuclear matter formed in non-central Au + Au collisions at center-of-mass energies 7.7≤sNN≤62.4 GeV. The whole volume of an expanding fireball is subdivided into small cubic cells. Then, we trace the final Λ and Λ¯ hyperons back to their last interaction point within a certain cell. Extracting the bulk parameters, such as energy density, net baryon density, and net strangeness of the hot and dense medium in the cell, one can obtain the cell temperature and the chemical potentials at the time of the hyperon emission. To do this, the extracted characteristics have to be fitted to the statistical model (SM) of ideal hadron gas. After that, the vorticity of nuclear matter and polarization of both hyperons are calculated. We found that the polarization of both Λ and Λ¯ increases with decreasing energy of heavy-ion collisions. The stronger polarization of Λ¯ is explained by (i) the slightly different freeze-out conditions of both hyperons and (ii) the different space–time distributions of Λ and Λ¯.

scholarly journals Isospin Physics in Heavy-Ion Collisions at Intermediate Energies

1998 ◽  
Vol 07 (02) ◽  
pp. 147-229 ◽  
Author(s):  
Bao-An Li ◽  
Che Ming Ko ◽  
Wolfgang Bauer
Keyword(s):  
Equation Of State ◽  
Nuclear Matter ◽  
Cross Sections ◽  
Heavy Ion Collisions ◽  
Transport Model ◽  
Transient State ◽  
Heavy Ion ◽  
Nucleon Nucleon ◽  
Asymmetric Nuclear Matter ◽  
Ion Collisions

In nuclear collisions induced by stable or radioactive neutron-rich nuclei a transient state of nuclear matter with an appreciable isospin asymmetry as well as thermal and compressional excitation can be created. This offers the possibility to study the properties of nuclear matter in the region between symmetric nuclear matter and pure neutron matter. In this review, we discuss recent theoretical studies of the equation of state of isospin-asymmetric nuclear matter and its relations to the properties of neutron stars and radioactive nuclei. Chemical and mechanical instabilities as well as the liquid-gas phase transition in asymmetric nuclear matter are investigated. The in-medium nucleon-nucleon cross sections at different isospin states are reviewed as they affect significantly the dynamics of heavy ion collisions induced by radioactive beams. We then discuss an isospin-dependent transport model, which includes different mean-field potentials and cross sections for the proton and neutron, and its application to these reactions. Furthermore, we review the comparisons between theoretical predictions and available experimental data. In particular, we discuss the study of nuclear stopping in terms of isospin equilibration, the dependence of nuclear collective flow and balance energy on the isospin-dependent nuclear equation of state and cross sections, the isospin dependence of total nuclear reaction cross sections, and the role of isospin in preequilibrium nucleon emissions and subthreshold pion production.

Thermodynamic instabilities in high energy heavy-ion collisions

2015 ◽  
Vol 29 (18) ◽  
pp. 1550092
Author(s):  
A. Lavagno ◽  
D. Pigato ◽  
G. Gervino
Keyword(s):  
Phase Transition ◽  
Nuclear Matter ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
High Energy ◽  
Baryon Density ◽  
Mechanical Instability ◽  
Ion Collisions ◽  
Nuclear Ground State ◽  
Strangeness Content

One of the very interesting aspects of high energy heavy-ion collisions experiments is a detailed study of the thermodynamical properties of strongly interacting nuclear matter away from the nuclear ground state. In this direction, many efforts were focused on searching for possible phase transitions in such collisions. We investigate thermodynamic instabilities in a hot and dense nuclear medium where a phase transition from nucleonic matter to resonance-dominated [Formula: see text]-matter can take place. Such a phase transition can be characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the strangeness concentration) in asymmetric nuclear matter. In analogy with the liquid–gas nuclear phase transition, hadronic phases with different values of antibaryon–baryon ratios and strangeness content may coexist. Such a physical regime could be, in principle, investigated in the future high-energy compressed nuclear matter experiments which will make it possible to create compressed baryonic matter with a high net baryon density.

Study of Signals of Hot and Dense Nuclear Matter in Heavy-Ion Collisions at NICA Energies Using Micro- and Macroscopic Models

2021 ◽  
Vol 52 (4) ◽  
pp. 544-548
Author(s):  
E. E. Zabrodin ◽  
A. S. Botvina ◽  
L. V. Bravina ◽  
G. Kh. Eyyubova ◽  
Yu. B. Ivanov ◽  
...  
Keyword(s):  
Nuclear Matter ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Macroscopic Models ◽  
Ion Collisions ◽  
Dense Nuclear Matter

scholarly journals Properties of ρ(770)0, K*(892), ϕ(1020), ∑(1385)±, Λ(1520) and Ξ(1530)0 resonances in heavy-ion collisions at a center of mass energy of SNN=4-11GeV and their reconstruction using the MPD detector at NICA

2021 ◽  
Vol 2103 (1) ◽  
pp. 012140
Author(s):  
D A Ivanishchev ◽  
D O Kotov ◽  
E L Kryshen ◽  
M V Malaev ◽  
V G Riabov ◽  
...  
Keyword(s):  
Heavy Ion Collisions ◽  
Center Of Mass ◽  
Feasibility Studies ◽  
Heavy Ion ◽  
Hadronic Decay ◽  
Relativistic Heavy Ion Collisions ◽  
Dense Medium ◽  
Center Of Mass Energy ◽  
Ion Collisions ◽  
Physical Program

Abstract The short-lived hadronic resonances are used to study properties of the hot and dense medium produced in relativistic heavy-ion collisions. Due to their short lifetimes, the resonance yields and masses measured in the hadronic channels are sensitive to rescattering and regeneration effects in the hadronic phase. The measurement of resonances is foreseen in the physical program of the MPD experiment at NICA in heavy-ion collisions at S N N = 4 - 11 GeV , in the range of energies where extensive measurements of resonances are not experimentally available. In this contribution, we explore the sensitivity of the ρ(770)0, K*(892), ϕ(1020), ∑(1385)±, Λ(1520) and Ξ(1530)0 resonances measured in the hadronic decay channels to different stages of the heavy-ion collisions at NICA energies and report the feasibility studies for the reconstruction of resonances in the MPD setup

RELATIVISTIC HEAVY-ION COLLISIONS: RECENT RESULTS FROM RHIC

2004 ◽  
Vol 19 (07) ◽  
pp. 1111-1118
Author(s):  
D. HARDTKE
Keyword(s):  
Energy Loss ◽  
Nuclear Matter ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
High Energy ◽  
Jet Quenching ◽  
Relativistic Heavy Ion Collisions ◽  
Dense Medium ◽  
Relativistic Heavy Ion Collider ◽  
Ion Collisions

High energy collisions of heavy nuclei at the Relativistic Heavy-Ion Collider permit the study of nuclear matter at extreme densities and temperatures. Selected experimental highlights from the early RHIC program are presented. Measurements of the total multiplicity in heavy-ion collisions show a surprising similarity to measurements in e+e- collisions after nuclear geometry is taken into account. RHIC has sufficient center-of-mass energy to use large transverse momentum particles and jets as a probe of the nuclear medium. Signatures of "jet quenching" due to radiative gluon energy loss of fast partons in a dense medium are observed for the first time at RHIC. In order to account for this energy loss, initial energy densities of 30-100 times normal nuclear matter density are required.

scholarly journals Emergent hydrodynamics in microscopic modeling of early stage of relativistic heavy-ion collisions

2020 ◽  
Vol 56 (10) ◽  
Author(s):  
L. V. Bravina ◽  
E. E. Zabrodin
Keyword(s):  
Energy Density ◽  
Heavy Ion Collisions ◽  
Early Stage ◽  
Heavy Ion ◽  
Baryon Density ◽  
Relativistic Heavy Ion Collisions ◽  
Ion Collisions ◽  
Dense Nuclear Matter ◽  
Microscopic Modeling ◽  
String Models

AbstractTime evolution of hot and dense nuclear matter produced in central gold-gold collisions at energies between $$E_{lab} = 10$$ E lab = 10 and 160 AGeV is studied within two transport string models, UrQMD and QGSM. In contrast to the previous studies, here we investigate the macroscopic characteristics of the system before the state of chemical and thermal equilibrium is attained. For all energies in question two interesting observations are made for times starting already from $$t \ge 1$$ t ≥ 1  fm/c. (1) The matter in the cell expands almost isentropically with nearly constant entropy per baryon. (2) Pressure in the cell appears to be very close to the pressure calculated for equilibrated hadron gas with the same values of energy density, baryon density and strangeness density. The pressure linearly depends on the energy density, $$P = a(\sqrt{s}) \varepsilon $$ P = a ( s ) ε . Therefore, both observations endorses the formal application of relativistic hydrodynamics from the very early stages of heavy-ion collisions, despite of the fact that the matter in the fireball is out of equilibrium.

PROBING THE NUCLEAR MATTER AT HIGH BARYON AND ISOSPIN DENSITY WITH HEAVY ION COLLISIONS

2010 ◽  
Vol 19 (05n06) ◽  
pp. 856-868
Author(s):  
M. DI TORO ◽  
M. COLONNA ◽  
G. FERINI ◽  
V. GIORDANO ◽  
V. GRECO ◽  
...  
Keyword(s):  
Nuclear Matter ◽  
Quark Matter ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
High Energy ◽  
Baryon Density ◽  
Mixed Phase ◽  
Hadronic Matter ◽  
Ion Collisions ◽  
Asymmetric Matter

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. High Energy Collisions are studied in order to access nuclear matter properties at high density. Particular attention is devoted to the selection of observables sensitive to the poorly known symmetry energy at high baryon density, of large fundamental interest, even for the astrophysics implications. Using fully consistent covariant transport simulations built on effective field theories we are testing isospin observables ranging from nucleon/cluster emissions, collective flows (in particular the elliptic, squeeze out, part) and meson production. The possibility to shed light on the controversial neutron/proton effective mass splitting in asymmetric matter is also stressed. The "symmetry" repulsion at high baryon density will also lead to an "earlier" hadron-deconfinement transition in n -rich matter. The phase transition of hadronic to quark matter at high baryon and isospin density is analyzed. Nonlinear relativistic mean field models are used to describe hadronic matter, and the MIT bag model is adopted for quark matter. The boundaries of the mixed phase and the related critical points for symmetric and asymmetric matter are obtained. Isospin effects appear to be rather significant. The binodal transition line of the ( T ,ρB) diagram is lowered in a region accessible to heavy ion collisions in the energy range of the new planned FAIR/NICA facilities. Some observable effects of the mixed phase are suggested, in particular a neutron distillation mechanism. Theoretically a very important problem appears to be the suitable treatment of the isovector part of the interaction in effective QCD lagrangian approaches.

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