Possible octupole deformation of ${}^{208}$Pb and the ultracentral $v_2$ to $v_3$ puzzle

Abstract

Recent measurements have established the sensitivity of ultracentral heavy-ion collisions to the deformation parameters of non-spherical nuclei. In the case of ${}^{129}$Xe collisions, a quadrupole deformation of the nuclear profile led to an enhancement of elliptic flow in the most central collisions. In ${}^{208}$Pb collisions a discrepancy exists in similar centralities, where either elliptic flow is over-predicted or triangular flow is under-predicted 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 ${}^{208}$Pb 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 revisit the $v_2$-to-$v_3$ puzzle in ultracentral collisions, including new constraints from recent measurements of the triangular cumulant ratio $v_3\left\{4\right\}/v_3\left\{2\right\}$ 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 ${\beta }_3\lesssim 0.0375$ for ${}^{208}$Pb, 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.

arXiv comment11 pages, 11 figures, v2 cosmetic changes to figures

References in corpus (70)

• Microscopic Models for Ultrarelativistic Heavy Ion Collisions
• Relativistic Hadron-Hadron Collisions in the Ultra-Relativistic Quantum Molecular Dynamics Model (UrQMD)
• Nuclear ground-state masses and deformations: FRDM(2012)
• Neutron Star Structure and the Neutron Radius of 208Pb
• Elliptic and triangular flow in event-by-event (3+1)D viscous hydrodynamics
• Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at 2.76 TeV
• Derivation of transient relativistic fluid dynamics from the Boltzmann equation
• QCD Equation of State and Hadron Resonance Gas
• Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering
• 3+1D hydrodynamic simulation of relativistic heavy-ion collisions
• Applying Bayesian parameter estimation to relativistic heavy-ion collisions: simultaneous characterization of the initial state and quark-gluon plasma medium
• 200 A GeV Au+Au collisions serve a nearly perfect quark-gluon liquid
• Alternative ansatz to wounded nucleon and binary collision scaling in high-energy nuclear collisions
• Neutron skins and neutron stars in the multi-messenger era
• The importance of the bulk viscosity of QCD in ultrarelativistic heavy-ion collisions
• Event-by-event fluctuations in perturbative QCD + saturation + hydro model: pinning down QCD matter shear viscosity in ultrarelativistic heavy-ion collisions
• Centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• One fluid to rule them all: viscous hydrodynamic description of event-by-event central p+p, p+Pb and Pb+Pb collisions at $\sqrt{s}=5.02$ TeV
• Collective dynamics of the high-energy proton-nucleus collisions
• Neutron skin of ${}^{208}$Pb from Coherent Pion Photoproduction
• Global systematics of octupole excitations in even-even nuclei
• Transport Coefficients of Bulk Viscous Pressure in the 14-moment approximation
• Correlated event-by-event fluctuations of flow harmonics in Pb-Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV
• Bulk Viscosity Effects in Event-by-Event Relativistic Hydrodynamics
• Measurement of higher-order harmonic azimuthal anisotropy in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV
• Particle spectra in Pb-Pb collisions at 2.76 TeV
• Energy density of the Glasma
• Azimuthal anisotropy in U+U and Au+Au collisions at RHIC
• Anisotropic flow in Xe-Xe collisions at $\sqrt{{\mathbf{s}}_{\mathrm{NN}}}=5.44$ TeV
• Investigations of anisotropic flow using multi-particle azimuthal correlations in pp, p-Pb, Xe-Xe, and Pb-Pb collisions at the LHC
• Constraining the hadronic spectrum through QCD thermodynamics on the lattice
• Bulk viscosity-driven suppression of shear viscosity effects on the flow harmonics at RHIC
• Linear and cubic response to the initial eccentricity in heavy-ion collisions
• Hydrodynamic predictions for 5.44 TeV Xe+Xe collisions
• Energy dependence and fluctuations of anisotropic flow in Pb-Pb collisions at $\sqrt{{\text{s}}_{\text{NN}}}=5.02$ and $2.76$ TeV
• Transverse momentum spectra and nuclear modification factors of charged particles in Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV
• Hydrodynamic Predictions for Pb+Pb Collisions at 5.02 A TeV
• Comparison of heavy-ion transport simulations: Collision integral with pions and $\Delta$ resonances in a box
• Effect of the QCD equation of state and strange hadronic resonances on multiparticle correlations in heavy ion collisions
• Anisotropic flow in event-by-event ideal hydrodynamic simulations of sqrt(s_{NN})=200 GeV Au+Au collisions
• Measurement of flow harmonics with multi-particle cumulants in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV with the ATLAS detector
• Predictions for 5.023 TeV Pb+Pb collisions at the LHC
• Extracting the shear viscosity of the quark-gluon plasma from flow in ultra-central heavy-ion collisions
• Solutions of Conformal Israel-Stewart Relativistic Viscous Fluid Dynamics
• Relative flow fluctuations as a probe of initial state fluctuations
• Neutron skins and neutron stars
• Resonance contributions to HBT correlation radii
• Early Time Dynamics of Gluon Fields in High Energy Nuclear Collisions
• Shrinking the Quark Gluon Plasma
• Multi-particle and charge-dependent azimuthal correlations in heavy-ion collisions at the Relativistic Heavy-Ion Collider
• Hydrodynamic predictions for 5.02 TeV Pb-Pb collisions
• Sensitivity of flow harmonics to sub-nucleon scale fluctuations in heavy ion collisions
• Collision Geometry and Flow in Uranium+Uranium Collisions
• Constraining the quadrupole deformation of atomic nuclei with relativistic nuclear collisions
• Symmetric cumulants and event-plane correlations in Pb+Pb collisions
• Shape and flow fluctuations in ultra-central Pb+Pb collisions at the LHC
• Predictions for multiplicities and flow harmonics in 5.44 TeV Xe+Xe collisions at the CERN Large Hadron Collider
• Extracting the bulk viscosity of the quark-gluon plasma
• Fluctuations of anisotropic flow in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector
• Hydrodynamic Predictions for Mixed Harmonic Correlations in 200 GeV Au+Au Collisions
• Glauber Monte Carlo predictions for ultra-relativistic collisions with ${}^{16}\mathrm{O}$
• Elliptic flow fluctuations in central collisions of spherical and deformed nuclei
• Study of the sensitivity of observables to hot spot size in heavy ion collisions
• Assessing saturation physics explanations of collectivity in small collision systems with the IP-Jazma model
• Examination of Flow and Non-Flow Factorization Methods in Small Collision Systems
• Elliptic flow in ultra-relativistic collisions with polarized deuterons
• Spectra and elliptic flow of thermal photons from full overlap U+U collisions at RHIC
• Elliptic flow in ultra-relativistic collisions with light polarized nuclei
• Primordial fluctuations in heavy-ion collisions
• Ultracentral Collisions of Small and Deformed Systems at RHIC: $UU$, $dAu$, ${}^{9}BeAu$, ${}^{9}Be{}^{9}Be$, ${}^{3}He{}^{3}He$, and ${}^{3}HeAu$ Collisions

Cited by in corpus (17)

• Shape of atomic nuclei in heavy ion collisions
• ${}^{16}{\mathrm{O}}^{16}\mathrm{O}$ at RHIC and the LHC comparing $\alpha$ clustering vs substructure
• The mean transverse momentum of ultracentral heavy-ion collisions: A new probe of hydrodynamics
• Accessing the shape of atomic nuclei with relativistic collisions of isobars
• Scaling approach to nuclear structure in high-energy heavy-ion collisions
• Measures of azimuthal anisotropy in high-energy collisions
• Non-Gaussian transverse momentum fluctuations from impact parameter fluctuations
• Examination of nucleon distribution with Bayesian imaging for isobar collisions
• Hydrodynamic fluctuations and ultra-central flow puzzle in heavy-ion collisions
• Assessing the ultracentral flow puzzle in hydrodynamic modeling of heavy-ion collisions
• Pre-Equilibrium Evolution of Conserved Charges with ICCING Initial Conditions
• Gluonic Hot Spot Initial Conditions in Heavy-Ion Collisions
• Multi-particle correlations, cumulants, and moments sensitive to fluctuations in rare-probe azimuthal anisotropy in heavy ion collisions
• Impact parameter dependence of anisotropic flow: Bayesian reconstruction in ultracentral nucleus-nucleus collisions
• Impact of Multiplicity Fluctuations on Entropy Scaling Across System Size
• Scaling approach to rigid and soft nuclear deformation through flow fluctuations in high-energy nuclear collisions
• Study of octupole deformations in Pb-Pb collisions at 5.02 TeV