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Update of the Three-fluid Hydrodynamics-based Event Simulator: light-nuclei production in heavy-ion collisions

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 Added by Yuri B. Ivanov
 Publication date 2020
  fields
and research's language is English




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We present an update of the event generator based on the three-fluid dynamics (3FD), complemented by Ultra-relativistic Quantum Molecular Dynamics (UrQMD) for the late stage of the nuclear collision~-- the three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD final State interactions (THESEUS). Two modifications are introduced. The THESEUS table of hadronic resonances is made consistent with that of the underlying 3FD model. The main modification is that the generator is extended to simulate the light-nuclei production in relativistic heavy-ion collisions, on the equal basis with hadrons. These modifications are illustrated by applications to the description of available experimental data. The first run of the updated generator revealed a good reproduction of the NA49 data on the light nuclei. The reproduction is achieved without any extra parameters, while the coalescence approach in 3FD requires special tuning of the coalescence coefficients for each light nucleus separately.



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Relativistic heavy ion collisions, which are performed at large experimental programs such as Relativistic Heavy Ion Colliders (RHIC) STAR experiment and the Large Hadron Colliders (LHC) experiments, can create an extremely hot and dense state of the matter known as the quark gluon plasma (QGP). A huge amount of sub-nucleonic particles are created in the collision processes and their interaction and subsequent evolution after the collision takes place is at the core of the understanding of the matter that builds up the Universe. It has recently been shown that event-by-event fluctuations in the spatial distribution between different collision events have great impact on the particle distributions that are measured after the evolution of the created system. Specifically, these distributions are greatly responsible for generating the observed azimuthal anisotropy in measurements. Furthermore, the eventual cooling and expansion of the fluctuating system can become very complex due to lumps of energy density and temperature, which affects the interaction of the particles that traverse the medium. In this configuration, heavy flavor particles play a special role, as they are generally created at the initial stages of the process and have properties that allow them to retain memory from the interactions within the whole evolution of the system. However, the comparison between experimental data and theoretical or phenomenological predictions on the heavy flavor sector cannot fully explain the heavy quarks coupling with the medium and their subsequent hadronization process. [Full abstract in file]
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