Autor(es)

Carzon, P. ; Rao, S. ; Luzum, M. ; Sievert, M. ; Noronha-Hostler, J.

• Tipo de documento: Artigo Científico
• Fonte: PHYSICAL REVIEW C; v. 102, n. 5, p. 10-pg., 2020-11-09.

Resumo

Recent measurements have established the sensitivity of ultracentral heavy-ion collisions to the deformation parameters of nonspherical nuclei. In the case of Xe-129 collisions, a quadrupole deformation of the nuclear profile led to an enhancement of elliptic flow in the most central collisions. In Pb-208 collisions a discrepancy exists in similar centralities, where either elliptic flow is overpredicted or triangular flow is underpredicted by hydrodynamic models; this is known as the v(2)-to-v(3) puzzle in ultracentral collisions. Motivated by low-energy nuclear structure calculations, we consider the possibility that Pb-208 nuclei could have a pear-shape deformation (octupole), which has the effect of increasing triangular flow in central PbPb collisions. Using the recent data from ALICE and ATLAS, we reexamine the v(2)-to-v(3) puzzle in ultracentral collisions, including new constraints from recent measurements of the triangular cumulant ratio v(3){4}/v(3){2} and comparing two different hydrodynamic models. We find that while an octupole deformation would slightly improve the ratio between v(2) and v(3), it is at the expense of a significantly worse triangular flow cumulant ratio. In fact, the latter observable prefers no octupole deformation, with beta(3) less than or similar to 0.0375 for Pb-208, and is therefore consistent with the expectation for a doubly-magic nucleus even at top collider energies. The v(2)-to-v(3) puzzle remains a challenge for hydrodynamic models. (AU)

• Processo FAPESP: 17/05685-2 - Física hadrônica em colisões nucleares de altas energias
• Beneficiário: Jun Takahashi
• Modalidade de apoio: Auxílio à Pesquisa - Projetos Especiais
• 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: 18/24720-6 - Exploração do diagrama de fase da QCD
• Beneficiário: Frédérique Marie Brigitte Sylvie Grassi
• Modalidade de apoio: Auxílio à Pesquisa - Temático