scholarly journals Production of light nuclei at colliders – coalescence vs. thermal model

2020 ◽  
Vol 229 (22-23) ◽  
pp. 3559-3583
Author(s):  
Stanisław Mrówczyński
Keyword(s):  
Correlation Function ◽  
Thermal Model ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Light Nuclei ◽  
Relativistic Heavy Ion Collisions ◽  
Final State ◽  
Coalescence Model ◽  
Ion Collisions ◽  
Final State Interactions

AbstractThe production of light nuclei in relativistic heavy-ion collisions is well described by both the thermal model, where light nuclei are in equilibrium with hadrons of all species present in a fireball, and by the coalescence model, where light nuclei are formed due to final-state interactions after the fireball decays. We present and critically discuss the two models and further on we consider two proposals to falsify one of the models. The first proposal is to measure a yield of exotic nuclide 4Li and compare it to that of 4He. The ratio of yields of the nuclides is quite different in the thermal and coalescence models. The second proposal is to measure a hadron-deuteron correlation function which carries information whether a deuteron is emitted from a fireball together with all other hadrons, as assumed in the thermal model, or a deuteron is formed only after nucleons are emitted, as in the coalescence model. The p − 3He correlation function is of interest in context of both proposals: it is needed to obtain the yield of 4Li which decays into p and 3He, but the correlation function can also tell us about an origin of 3He.

scholarly journals Production of $$^4\mathrm{Li}$$ and $$p\!-\!^3\mathrm{He}$$ correlation function in relativistic heavy-ion collisions

2020 ◽  
Vol 56 (7) ◽  
Author(s):  
Sylwia Bazak ◽  
Stanisław Mrówczyński
Keyword(s):  
Correlation Function ◽  
Heavy Ion Collisions ◽  
Coulomb Repulsion ◽  
Heavy Ion ◽  
Light Nuclei ◽  
Relativistic Heavy Ion Collisions ◽  
Weakly Bound ◽  
Ion Collisions ◽  
Internal Structures ◽  
The Masses

Abstract The thermal and coalescence models both describe well yields of light nuclei produced in relativistic heavy-ion collisions at LHC. We propose to measure the yield of $$^4\mathrm{Li}$$ 4 Li and compare it to that of $$^4\mathrm{He}$$ 4 He to falsify one of the models. Since the masses of $$^4\mathrm{He}$$ 4 He and $$^4\mathrm{Li}$$ 4 Li are almost equal, the yield of $$^4\mathrm{Li}$$ 4 Li is about 5 times bigger than that of $$^4\mathrm{He}$$ 4 He in the thermal model because of different numbers of spin states of the two nuclides. Their internal structures are, however, very different: the alpha particle is well bound and compact while $$^4\mathrm{Li}$$ 4 Li is weakly bound and loose. Consequently, the ratio of yields of $$^4\mathrm{Li}$$ 4 Li to $$^4\mathrm{He}$$ 4 He is significantly smaller in the coalescence model and it strongly depends on the collision centrality. Since the nuclide $$^4\mathrm{Li}$$ 4 Li is unstable and it decays into $$^3\mathrm{He}$$ 3 He and p, the yield of $$^4\mathrm{Li}$$ 4 Li can be experimentally obtained through a measurement of the $$p\!-\!^3\mathrm{He}$$ p - 3 He correlation function. The function carries information not only about the yield of $$^4\mathrm{Li}$$ 4 Li but also about the source of $$^3\mathrm{He}$$ 3 He and allows one to determine through a source-size measurement whether of $$^3\mathrm{He}$$ 3 He is directly emitted from the fireball or it is formed afterwards. We compute the correlation function taking into account the s-wave scattering and Coulomb repulsion together with the resonance interaction responsible for the $$^4\mathrm{Li}$$ 4 Li nuclide. We discuss how to infer information about an origin of $$^3\mathrm{He}$$ 3 He from the correlation function, and finally a method to obtain the yield of $$^4\mathrm{Li}$$ 4 Li is proposed.

scholarly journals 4He versus 4Li and production of light nuclei in relativistic heavy-ion collisions

2018 ◽  
Vol 33 (25) ◽  
pp. 1850142 ◽  
Author(s):  
Sylwia Bazak ◽  
Stanisław Mrówczyński
Keyword(s):  
Thermal Model ◽  
Heavy Ion Collisions ◽  
Degrees Of Freedom ◽  
Heavy Ion ◽  
Light Nuclei ◽  
Relativistic Heavy Ion Collisions ◽  
Weakly Bound ◽  
Ion Collisions ◽  
Peripheral Collisions ◽  
The Masses

We propose to measure the yields of 4He and 4Li in relativistic heavy-ion collisions to clarify a mechanism of light nuclei production. Since the masses of 4He and 4Li are almost equal, the yield of 4Li predicted by the thermal model is five times bigger than that of 4He which reflects the different numbers of internal degrees of freedom of the two nuclides. Their internal structures are, however, very different: the alpha particle is well bound and compact while 4Li is weakly bound and loose. Within the coalescence model, the ratio of yields of 4Li to 4He is shown to be significantly smaller than that in the thermal model and the ratio decreases fast from central to peripheral collisions of relativistic heavy-ion collisions because the coalescence rate strongly depends on the nucleon source radius. Since the nuclide 4Li is unstable and it decays into 3He and p after roughly 30 fm/c, the yield of 4Li can be experimentally obtained through a measurement of the 3He[Formula: see text]p correlation function.

Production of light nuclei in relativistic heavy-ion collisions

1994 ◽  
Vol 50 (2) ◽  
pp. 1077-1084 ◽  
Author(s):  
J. Barrette ◽  
R. Bellwied ◽  
P. Braun-Munzinger ◽  
W. E. Cleland ◽  
T. M. Cormier ◽  
...  
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Light Nuclei ◽  
Relativistic Heavy Ion Collisions ◽  
Ion Collisions

POPULATION OF MULTI-QUARK STATES IN EXOTIC MULTIPLETS AND THERMALIZATION IN ULTRA-RELATIVISTIC HEAVY ION COLLISIONS

2008 ◽  
Vol 17 (06) ◽  
pp. 965-1014 ◽  
Author(s):  
STEFAN SCHERER ◽  
MARCUS BLEICHER ◽  
STEPHANE HAUSSLER ◽  
HORST STÖCKER
Keyword(s):  
Phase Space ◽  
Thermal Model ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Recent Discussion ◽  
Ion Collisions ◽  
Model Predictions ◽  
Exotic Hadrons ◽  
Equal Population

The recent discussion about experimental evidence for pentaquark states has revitalized the interest in exotic hadrons. If such states really exist, it is natural to assume that they will be formed at the late hadronization stage of ultra-relativistic heavy ion collisions, given the success of quark recombination models in the description of hadronization. Here, we apply the qMD model to study the formation of color neutral exotic multi-quark clusters at hadronization. We search for color neutral clusters made up of up to six color charges, respectively. We thus obtain estimates for the numbers and phase space distributions of exotic hadronic states produced by clustering in heavy ion collisions, including the members of the pentaquark multiplets. We obtain particle abundances that are smaller than thermal model predictions. Moreover, the results obtained in recombination from ultra-relativistic heavy ion collisions can be compared to the estimates based on equal population of the corresponding multiplets, and to results from fully thermalized systems. We find that the distribution of exotic hadrons from recombination over large multiplets provides a sensitive signal for thermalization and decorrelation of the initial, non-equilibrium state of the collision.

scholarly journals Kinetic evolution and correlation of fluctuations in an expanding quark gluon plasma

2018 ◽  
Vol 33 (08) ◽  
pp. 1850040 ◽  
Author(s):  
Golam Sarwar ◽  
Jan-e Alam
Keyword(s):  
Correlation Function ◽  
Power Spectrum ◽  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Thermodynamic Quantities ◽  
Dirac Delta ◽  
Ion Collisions

Evolution of spatially anisotropic perturbation created in the system formed after Relativistic Heavy Ion Collisions has been studied. The microscopic evolution of the fluctuations has been examined within the ambit of Boltzmann Transport Equation (BTE) in a hydrodynamically expanding background. The expansion of the background composed of quark gluon plasma (QGP) is treated within the framework of relativistic hydrodynamics. Spatial anisotropic fluctuations with different geometries have been evolved through Boltzmann equation. It is observed that the trace of such fluctuation survives the evolution. Within the relaxation time approximation, analytical results have been obtained for the evolution of these anisotropies. Explicit relations between fluctuations and transport coefficients have been derived. The mixing of various Fourier (or k) modes of the perturbations during the evolution of the system has been explicitly demonstrated. This study is very useful in understanding the presumption that the measured anisotropies in the data from heavy ion collisions at relativistic energies imitate the initial state effects. The evolution of correlation function for the perturbation in pressure has been studied and shows that the initial correlation between two neighbouring points in real space evolves to a constant value at later time which gives rise to Dirac delta function for the correlation function in Fourier space. The power spectrum of the fluctuation in thermodynamic quantities (like temperature estimated in this work) can be connected to the fluctuation in transverse momentum of the thermal hadrons measured experimentally. The bulk viscous coefficient of the QGP has been estimated by using correlations of pressure fluctuation with the help of Green–Kubo relation. Angular power spectrum of the anisotropies has been estimated in the appendix.

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