Abstract

The measurements of the (anti)deuterons elliptic flow ($v_2$) and the first measurements of triangular flow ($v_3$) in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon collisions $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are presented. A mass ordering at low transverse momentum ($p_{\rm T}$) is observed when comparing these measurements with those of other identified hadrons, as expected from relativistic hydrodynamics. The measured (anti)deuterons $v_2$ lies between the predictions from the simple coalescence and blast-wave models, which provide a good description of the data only for more peripheral and for more central collisions, respectively. The mass number scaling, which is violated for $v_2$, is approximately valid for the (anti)deuterons $v_3$. The measured $v_2$ and $v_3$ are also compared with the predictions from a coalescence approach with phase-space distributions of nucleons generated by iEBE-VISHNU with AMPT initial conditions coupled with UrQMD, and from a dynamical model based on relativistic hydrodynamics coupled to the hadronic afterburner SMASH. The model predictions are consistent with the data within the uncertainties in mid-central collisions, while a deviation is observed in central centrality intervals.

Highlights

  • The production mechanism of lightnuclei in highenergy hadronic collisions is still not fully clear and is under intense debate in the scientific community [1,2,3,4,5]

  • Thanks to the large data sample collected at higher energy, the elliptic flow measurement is performed in wider pT and up to a higher c√esnNtrNal=ity2.7in6teTrevVa,l compared to allowing for a that more in Pb-Pb collisions at differential comparison with the theoretical models

  • The elliptic and triangular flows of deuterons are measured in centrality intervals of 5% width and the results in wider centrality intervals are obtained as weighted averages of these measurements using the number of deuteron candidates, in the same centrality interval of 5% width as a weight, to what was performed in Ref. [19]

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Summary

INTRODUCTION

The production mechanism of light (anti)nuclei in highenergy hadronic collisions is still not fully clear and is under intense debate in the scientific community [1,2,3,4,5]. To address the open question of the survival of loosely bound multibaryon states in the hadron gas phase with intense rescattering, models based on relativistic hydrodynamics coupled to a hadronic afterburner have been recently developed [4,5] In these models, nucleons and light nuclei are produced at the phase transition using the Cooper-Frye formula [15], which describes the hadron production based on the. Local energy density of the fireball, and their yields are fixed to the value predicted by the thermal model at the chemical freeze-out temperature Their propagation through the hadronic medium is simulated based on known interaction cross sections and resonant states using different transport codes. Thanks to the large data sample collected at higher energy, the elliptic flow measurement is performed in wider pT and up to a higher c√esnNtrNal=ity2.7in6teTrevVa,l compared to allowing for a that more in Pb-Pb collisions at differential comparison with the theoretical models

THE ALICE DETECTOR
Event and track selections
Flow analysis techniques
Systematic uncertainties
AND DISCUSSION
Comparison with the blast-wave model predictions
Test of the coalescence hypothesis
Comparison with IEBE-VISHNU and coalescence calculations
SUMMARY
Abelev et al tified hadrons in
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