Search for the chiral magnetic effect in collisions between two isobars with deformed and neutron-rich nuclear structures

Abstract

Isobar collisions which were thought to have the same background and different magnetic fields provide an opportunity to verify the chiral magnetic effect (CME) in relativistic heavy-ion collisions. However, the first result from the RHIC-STAR isobar experiment did not observe the CME signal, but discovered that the backgrounds are different between ${}_{44}^{96}\text{Ru}{+}_{44}^{96}\text{Ru}$ and ${}_{40}^{96}\text{Zr}{+}_{40}^{96}\text{Zr}$ collisions. We test eighteen cases of Woods-Saxon parameter settings resulting from different nuclear deformation or nuclear structure effects using a mutiphase transport model. We find out that seven cases can reasonably reproduce three reference ratios measured by the STAR experiment. Considering both the halo-type neutron skin structure and CME-like charge separation, we demonstrate that it is difficult for the CME observables ($\Delta \delta$, $\Delta \delta$ ratio, $\Delta \gamma$ and $\Delta \gamma$ ratio) to distinguish the presence or absence of the CME, if the CME strength is weak in isobar collisions. It is because the final state interactions significantly weaken the initial CME signal, resulting in non-linear sensitivities of the CME observables to the CME strength. Therefore, more sensitive observables are required to search for the possible small CME signal in isobar collisions.

11 pages, 7 figures, final published version

References in corpus (14)

• The Chiral Magnetic Effect
• Nuclear symmetry energy probed by neutron skin thickness of nuclei
• Alternative ansatz to wounded nucleon and binary collision scaling in high-energy nuclear collisions
• Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy
• Charge conservation in RHIC and contributiuons to local parity violation observables
• Testing the Chiral Magnetic Effect with Central U+U collisions
• Azimuthal correlations from transverse momentum conservation and possible local parity violation
• Further developments of a multi-phase transport model for relativistic nuclear collisions
• Chiral magnetic effect reveals the topology of gauge fields in heavy-ion collisions
• Test the chiral magnetic effect with isobaric collisions
• Experimental searches for the chiral magnetic effect in heavy-ion collisions
• Impact of magnetic-field fluctuations on measurements of the chiral magnetic effect in collisions of isobaric nuclei
• Novel mechanism for electric quadrupole moment generation in relativistic heavy-ion collisions
• Impact of event activity variable on the ratio of observables in isobar collisions

Cited by in corpus (11)

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• Effect of nuclear structure on particle production in relativistic heavy-ion collisions using the AMPT model
• Production and anisotropic flow of thermal photons in collision of $\alpha$-clustered carbon with heavy nuclei at relativistic energies
• Machine learning study to identify collective flow in small and large colliding systems
• Difference between signal and background of the chiral magnetic effect relative to spectator and participant planes in isobar collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV
• Hydrodynamic simulations of directed flow for light hadrons in Au+Au and isobar collisions $\sqrt{s_{\text{NN}}}=$ 200 GeV
• Nuclear cluster structure effect in ${}^{16}$O+${}^{16}$O collisions at the top RHIC energy
• Signatures of an $\alpha$ + core structure in ${}^{44}$Ti + ${}^{44}$Ti collisions at $\sqrt{s_{NN}}=5.02$ TeV by a multiphase transport model
• Neural Unfolding of the Chiral Magnetic Effect in Heavy-Ion Collisions
• Two-gluon one-photon vertex in a magnetic field and its explicit one-loop approximation in the intermediate field strength regime
• The effect of electric and chiral magnetic conductivities on azimuthally fluctuating electromagnetic fields and observables in isobar collisions