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Bulk quantities in nuclear collisions from running-coupling k(T) factorization and hybrid simulations

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Autor(es):
Giannini, Andre, V ; Grassi, Frederique ; Luzum, Matthew
Número total de Autores: 3
Tipo de documento: Artigo Científico
Fonte: PHYSICAL REVIEW C; v. 100, n. 1, p. 10-pg., 2019-07-31.
Resumo

Starting from a color glass condensate (CGC) framework, based on a running-coupling improved k T -factorized formula, we calculate bulk observables in several heavy-ion collision systems. This is done in two ways: first we calculate the particle distribution directly implied from the CGC model, and we compare this to the case where it is instead used as the initial condition for a hybrid hydrodynamic simulation. In this way, we can assess the effects of hydrodynamic and hadronic evolution by quantifying how much they change the results from a pure initial state approach and, therefore, to what extent initial condition models can be directly compared to experimental data. We find that entropy production in subsequent hydrodynamic evolution can increase multiplicity by as much as 50%. However, disregarding a single overall normalization factor, the centrality, energy, and system size dependencies of charged hadron multiplicity are only affected at the similar to 5% level. Because of this, the parameter-free prediction for these dependencies gives reasonable agreement with experimental data whether or not hydrodynamic evolution is included. On the other hand, our model results are not compatible with the hypothesis that hydrodynamic evolution is present in large systems, but not in small systems like p-Pb, in which case the dependence of multiplicity on system size would be stronger than seen experimentally. Moreover, we find that hydrodynamic evolution significantly changes the distribution of momentum, so that observables such as the mean transverse momentum are very different from the initial particle production and much closer to measured data. Finally, we find that a good agreement to anisotropic flow data cannot be achieved due to the large eccentricity generated by this model. (AU)

Processo FAPESP: 17/14974-8 - Fenomenologia das colisões de íons pesados relativísticos: QCD em condições extremas
Beneficiário:André Veiga Giannini
Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
Processo FAPESP: 18/23677-0 - Dinâmica de tempo inicial de colisões hadrônicas além da aproximação gaussiana do condensado de vidro de cor
Beneficiário:André Veiga Giannini
Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
Processo FAPESP: 16/24029-6 - A investigação da força nuclear forte sob condições extremas
Beneficiário:Matthew William Luzum
Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
Processo FAPESP: 17/05685-2 - Física hadrônica em colisões nucleares de altas energias
Beneficiário:Jun Takahashi
Modalidade de apoio: Auxílio à Pesquisa - Projetos Especiais