scholarly journals Probing chemical freeze-out criteria in relativistic nuclear collisions with coarse grained transport simulations

2020 ◽  
Vol 56 (10) ◽  
Author(s):  
Tom Reichert ◽  
Gabriele Inghirami ◽  
Marcus Bleicher
Keyword(s):  
Chemical Potential ◽  
Transport Model ◽  
Relativistic Quantum ◽  
Coarse Graining ◽  
Coarse Grained ◽  
Quantum Molecular Dynamics ◽  
Novel Approach ◽  
Relativistic Nuclear Collisions ◽  
Chemical Freeze ◽  
Freeze Out

AbstractWe introduce a novel approach based on elastic and inelastic scattering rates to extract the hyper-surface of the chemical freeze-out from a hadronic transport model in the energy range from E$$_\mathrm {lab}=1.23$$ lab = 1.23  AGeV to $$\sqrt{s_\mathrm {NN}}=62.4$$ s NN = 62.4  GeV. For this study, the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model combined with a coarse-graining method is employed. The chemical freeze-out distribution is reconstructed from the pions through several decay and re-formation chains involving resonances and taking into account inelastic, pseudo-elastic and string excitation reactions. The extracted average temperature and baryon chemical potential are then compared to statistical model analysis. Finally we investigate various freeze-out criteria suggested in the literature. We confirm within this microscopic dynamical simulation, that the chemical freeze-out at all energies coincides with $$\langle E\rangle /\langle N\rangle \approx 1$$ ⟨ E ⟩ / ⟨ N ⟩ ≈ 1  GeV, while other criteria, like $$s/T^3=7$$ s / T 3 = 7 and $$n_\mathrm {B}+n_{\bar{\mathrm {B}}}\approx 0.12$$ n B + n B ¯ ≈ 0.12 fm$$^{-3}$$ - 3 are limited to higher collision energies.

scholarly journals Density Functional Hydrodynamics in Multiscale Pore Systems: Chemical Potential Drive

2020 ◽  
Vol 146 ◽  
pp. 01001
Author(s):  
Oleg Dinariev ◽  
Nikolay Evseev ◽  
Denis Klemin
Keyword(s):  
Density Functional ◽  
Fluid Transport ◽  
Chemical Potential ◽  
Transport Model ◽  
Effective Model ◽  
Pore Scale ◽  
Multiphase Transport ◽  
Novel Approach ◽  
Scale Modelling ◽  
Significant Generalization

We use the method of density functional hydrodynamics (DFH) to model compositional multiphase flows in natural cores at the pore-scale. In previous publications the authors demonstrated that DFH covers many diverse pore-scale phenomena, starting from those inherent in RCA and SCAL measurements, and extending to much more complex EOR processes. We perform the pore-scale modelling of multiphase flow scenarios by means of the direct hydrodynamic (DHD) simulator, which is a numerical implementation of the DFH. In the present work, we consider the problem of numerical modelling of fluid transport in pore systems with voids and channels when the range of pore sizes exceed several orders of magnitude. Such situations are well known for carbonate reservoirs, where narrow pore channels of micrometer range can coexist and interconnect with vugs of millimeter or centimeter range. In such multiscale systems one cannot use the standard DFH approach for pore-scale modeling, primarily because the needed increase in scanning resolution that is required to resolve small pores adequately, leads to a field of view reduction that compromises the representation of large pores. In order to address this challenge, we suggest a novel approach, in which transport in small-size pores is described by an upscaled effective model, while the transport in large pores is still described by the DFH. The upscaled effective model is derived from the exact DFH equations using asymptotic expansion in respect to small-size characterization parameter. This effective model retains the properties of DFH like chemical and multiphase transport, thus making it applicable to the same range of phenomena as DFH itself. The model is based on the concept that the transport is driven by gradients of chemical potentials of the components present in the mixture. This is a significant generalization of the Darcy transport model since the proposed new model incorporates diffusion transport in addition to the usual pressure-driven transport. In the present work we provide several multiphase transport numerical examples including: a) upscaling to chemical potential drive (CPD) model, b) combined modeling of large pores by DFH and small pores by CPD.

BLOCK ENTROPY ANALYSIS OF HEART RATE VARIABILITY SIGNALS

2006 ◽  
Vol 16 (07) ◽  
pp. 2093-2101 ◽  
Author(s):  
K. KARAMANOS ◽  
S. NIKOLOPOULOS ◽  
K. HIZANIDIS ◽  
G. MANIS ◽  
A. ALEXANDRIDI ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Heat Rate ◽  
Coarse Graining ◽  
Coarse Grained ◽  
Entropy Analysis ◽  
Data Set ◽  
Novel Approach ◽  
Data Files ◽  
Block Entropy ◽  
Artery Disease

In this paper we present a novel approach to the analysis of Heat Rate Variability (HRV) data, by coarse-graining analysis using the estimation of Block Entropies with the technique of lumping. HRV time series are generated from long recordings of Electrocardiograms (ECGs) and are then filtered in order to produce a coarse-grained symbolic dynamics. Block Entropy analysis is applied to these dynamics in order to examine its coarse-grained statistics. Our data set is comprised of two subsets, one of healthy subjects and another of Coronary Artery Disease (CAD) patients. It is found that Entropy analysis provides a quick and efficient tool for the differentiation of these series according to subject category. Healthy subjects provided more complex statistics compared to patients; specifically, the healthy data files provided higher values of block Entropies compared to patient ones. We also compare these results with the Correlation Dimension Estimation in order to establish coherency. We believe that this analysis may provide a useful statistical method towards the better understanding of the human cardiac system.

scholarly journals PRODUCTION AND RESCATTERING OF STRANGE BARYONS AT ENERGIES AVAILABLE AT THE CERN SUPER PROTON SYNCHROTRON IN A TRANSPORT MODEL WITH HADRON POTENTIALS

2012 ◽  
Vol 27 (03) ◽  
pp. 1250004 ◽  
Author(s):  
QINGFENG LI ◽  
ZHUXIA LI
Keyword(s):  
Transport Model ◽  
Relativistic Quantum ◽  
Mean Field ◽  
Field Potential ◽  
Heavy Ion ◽  
Transverse Mass ◽  
Proton Synchrotron ◽  
Quantum Molecular Dynamics ◽  
Super Proton Synchrotron ◽  
Strange Baryons

A mean-field potential version of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model is used to investigate the production of strange (anti-)baryons, especially the Λs and [Formula: see text]s, from heavy ion collisions at SPS energies. It is found that, with the consideration of both formed and pre-formed hadron potentials in UrQMD, the transverse mass and longitudinal rapidity distributions of experimental data of both Λs and [Formula: see text]s can be quantitatively explained fairly well. Our investigation also shows the equal importance of both the production mechanism and the rescattering process of hadrons for the final yield of strange baryons.

Forward–backward multiplicity correlation and event-by-event multiplicity fluctuation in nucleus–nucleus collisions at 200A GeV

2021 ◽  
pp. 2150021
Author(s):  
Sanjib Kumar Manna ◽  
Amitabha Mukhopadhyay ◽  
Provash Mali
Keyword(s):  
Transport Model ◽  
Relativistic Quantum ◽  
Cluster Formation ◽  
Simulated Data ◽  
Correlation Effect ◽  
Quantum Molecular Dynamics ◽  
Particle Correlation ◽  
Statistical Measures ◽  
Singly Charged ◽  
Bose Einstein

Correlation among singly charged particles emitted in the forward and backward pseudo-rapidity cones is measured in [Formula: see text]O-Ag/Br and [Formula: see text]S-Ag/Br interactions at an incident energy of [Formula: see text] GeV/nucleon. Event-by-event fluctuations in the charged particle multiplicities and their pseudo-rapidity values are also investigated in terms of some known statistical measures. Evidences of short-ranged particle correlation and cluster formation in the pseudo-rapidity space are found from our analysis. A microscopic transport model based on the Ultra-relativistic Quantum Molecular Dynamics could not match the experimental results. The differences between experimental observation and corresponding simulation could neither be accounted for even when a Bose–Einstein type of correlation effect is implemented into the simulated data.

Comparison study of the pT distributions of the charged particles in p–Pb interactions at LHC energies

2017 ◽  
Vol 32 (31) ◽  
pp. 1750167 ◽  
Author(s):  
Y. Ali ◽  
U. Tabassam ◽  
M. Suleymanov ◽  
A. S. Bhatti
Keyword(s):  
Transverse Momentum ◽  
Transport Model ◽  
Relativistic Quantum ◽  
Charged Particles ◽  
Medium Effect ◽  
Quantum Molecular Dynamics ◽  
Essential Difference ◽  
Momentum Range ◽  
Cronin Effect ◽  
Model Predictions

Transverse momentum [Formula: see text] distributions of primary charged particles were compared to simulations using the Ultra Relativistic Quantum Molecular Dynamics (UrQMD) transport model and the HIJING 1.0 model in minimum bias p–Pb collisions at [Formula: see text] in the pseudorapidity [Formula: see text] regions: [Formula: see text], [Formula: see text] and [Formula: see text] and in the transverse momentum range [Formula: see text]. The simulated distributions were then compared with the ALICE data and it was observed that UrQMD predicts systematically higher yields than HIJING 1.0. Both codes cannot describe the experimental data in the range of [Formula: see text], though in the region of [Formula: see text] the model predictions are very close to the experimental results for particles with [Formula: see text], [Formula: see text]. The ratio of the yield at forward pseudorapidity to that at [Formula: see text] was also studied. It was observed that the predictions of the models depend on [Formula: see text]. In the experiment there is no essential difference of yields for particles from the intervals of [Formula: see text], [Formula: see text] and [Formula: see text]. The differences are significant for the models where the ratios are systematically less than 1. This means that the results are not connected to a medium effect but reflect the Cronin effect. We are led to conclude that the codes cannot take into account satisfactorily the leading effect due to the asymmetric p–Pb fragmentation.

MULTIFRACTAL ANALYSIS OF CHARGED PARTICLE DISTRIBUTION IN 28Si-Ag/Br INTERACTION AT 14.5A GeV

Fractals ◽  
2012 ◽  
Vol 20 (03n04) ◽  
pp. 203-215 ◽  
Author(s):  
P. MALI ◽  
A. MUKHOPADHYAY ◽  
G. SINGH
Keyword(s):  
Charged Particle ◽  
Particle Production ◽  
Transport Model ◽  
Particle Density ◽  
Relativistic Quantum ◽  
Quantitative Difference ◽  
Quantum Molecular Dynamics ◽  
Particle Density Distribution ◽  
Charged Particle Density ◽  
Self Similar

The multifractal structure of one dimensional charged particle density distribution in 28 Si-Ag / Br interactions at 14.5 GeV per nucleon is investigated by using two different techniques. The experimental measurements are compared with a microscopic transport model of particle production based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD). Various parameters related to multifractality, for example the Lévy's index, are obtained. Our analysis shows that multifractal structure is present both in the experiment as well as in the simulation. As far as the self-similar nature of the density fluctuation is concerned, there exists, however, a small but definite quantitative difference between the two.

scholarly journals MULTISCALE, MULTIPHYSICS AND MULTIDOMAIN MODELS I: BASIC THEORY

2013 ◽  
Vol 12 (08) ◽  
pp. 1341006 ◽  
Author(s):  
GUO-WEI WEI
Keyword(s):  
Differential Geometry ◽  
Charge Transport ◽  
Chemical Potential ◽  
Transport Model ◽  
Coarse Grained ◽  
Elastic Model ◽  
Solvation Model ◽  
Energy Functionals ◽  
Solute Interactions ◽  
Elastic Dynamics

This work extends our earlier two-domain formulation of a differential geometry based multiscale paradigm into a multidomain theory, which endows us the ability to simultaneously accommodate multiphysical descriptions of aqueous chemical, physical and biological systems, such as fuel cells, solar cells, nanofluidics, ion channels, viruses, RNA polymerases, molecular motors, and large macromolecular complexes. The essential idea is to make use of the differential geometry theory of surfaces as a natural means to geometrically separate the macroscopic domain of solvent from the microscopic domain of solute, and dynamically couple continuum and discrete descriptions. Our main strategy is to construct energy functionals to put on an equal footing of multiphysics, including polar (i.e. electrostatic) solvation, non-polar solvation, chemical potential, quantum mechanics, fluid mechanics, molecular mechanics, coarse grained dynamics, and elastic dynamics. The variational principle is applied to the energy functionals to derive desirable governing equations, such as multidomain Laplace–Beltrami (LB) equations for macromolecular morphologies, multidomain Poisson–Boltzmann (PB) equation or Poisson equation for electrostatic potential, generalized Nernst–Planck (NP) equations for the dynamics of charged solvent species, generalized Navier–Stokes (NS) equation for fluid dynamics, generalized Newton's equations for molecular dynamics (MD) or coarse-grained dynamics and equation of motion for elastic dynamics. Unlike the classical PB equation, our PB equation is an integral-differential equation due to solvent–solute interactions. To illustrate the proposed formalism, we have explicitly constructed three models, a multidomain solvation model, a multidomain charge transport model and a multidomain chemo-electro-fluid-MD-elastic model. Each solute domain is equipped with distinct surface tension, pressure, dielectric function, and charge density distribution. In addition to long-range Coulombic interactions, various non-electrostatic solvent–solute interactions are considered in the present modeling. We demonstrate the consistency between the non-equilibrium charge transport model and the equilibrium solvation model by showing the systematical reduction of the former to the latter at equilibrium. This paper also offers a brief review of the field.

scholarly journals Sub-grid-scale effects in magnetised plasma turbulence

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Bogdan Teaca ◽  
Evgeny A. Gorbunov ◽  
Daniel Told ◽  
Alejandro Bañón Navarro ◽  
Frank Jenko
Keyword(s):  
Free Energy ◽  
Scale Effects ◽  
Turbulent Transport ◽  
Coarse Graining ◽  
Plasma Turbulence ◽  
Scale Space ◽  
Real Space ◽  
Coarse Grained ◽  
Spatial Density ◽  
Novel Approach

In the present paper, we use a coarse-graining approach to investigate the nonlinear redistribution of free energy in both position and scale space for weakly collisional magnetised plasma turbulence. For this purpose, we use high-resolution numerical simulations of gyrokinetic (GK) turbulence that span the proton–electron range of scales, in a straight magnetic guide field geometry. Accounting for the averaged effect of the particles’ fast gyro-motion on the slow plasma fluctuations, the GK approximation captures the dominant energy redistribution mechanisms in strongly magnetised plasma turbulence. Here, the GK system is coarse grained with respect to a cut-off scale, separating in real space the contributions to the nonlinear interactions from the coarse-grid scales and the sub-grid scales (SGS). We concentrate on the analysis of nonlinear SGS effects. Not only does this allow us to investigate the flux of free energy across the scales, but also to now analyse its spatial density. We find that the net value of scale flux is an order of magnitude smaller than both the positive and negative flux density contributions. The dependence of the results on the filter type is also analysed. Moreover, we investigate the advection of energy in position space. This rather novel approach for GK turbulence can help in the development of SGS models that account for advective unstable structures for space and fusion plasmas, and with the analysis of the turbulent transport saturation.

scholarly journals Energy Dependence of Particle Ratios in High Energy Nucleus-Nucleus Collisions: A USTFM Approach

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Inam-ul Bashir ◽  
Rameez Ahmad Parra ◽  
Hamid Nanda ◽  
Saeed Uddin
Keyword(s):  
Particle Production ◽  
Chemical Potential ◽  
Heavy Ion ◽  
High Energy ◽  
Ion Collisions ◽  
System A ◽  
Particle Ratios ◽  
High Degree ◽  
Chemical Freeze ◽  
Freeze Out

We study the identified particle ratios produced at mid-rapidity (y<0.5) in heavy-ion collisions, along with their correlations with the collision energy. We employ our earlier proposed unified statistical thermal freeze-out model (USTFM), which incorporates the effects of both longitudinal and transverse hydrodynamic flow in the hot hadronic system. A fair agreement seen between the experimental data and our model results confirms that the particle production in these collisions is of statistical nature. The variation of the chemical freeze-out temperature and the baryon chemical potential with respect to collision energies is studied. The chemical freeze-out temperature is found to be almost constant beyond the RHIC energy and is found to be close to the QCD predicted phase-transition temperature suggesting that the chemical freeze-out occurs soon after the hadronization takes place. The vanishing value of chemical potential at LHC indicates very high degree of nuclear transparency in the collision.

Sign in / Sign up

Export Citation Format

Share Document