Abstract
The unambiguous observation of a chiral magnetic effect (CME)–driven charge separation is the core aim of the isobar program at the Relativistic Heavy Ion Collider (RHIC), consisting of and collisions at GeV. We quantify the role of the spatial distributions of the nucleons in the isobars on both eccentricity and magnetic field strength within a relativistic hadronic transport approach (simulating many accelerated strongly interacting hadrons, SMASH). In particular, we introduce isospin-dependent nucleon-nucleon spatial correlations in the geometric description of both nuclei, deformation for and the so-called neutron skin effect for the neutron-rich isobar, i.e., . The main result of this study is a reduction of the magnetic field strength difference between and by a factor of 2, from to in peripheral collisions when the neutron-skin effect is included. Further, we find an increase of the eccentricity ratio between the isobars by up to 10% in ultracentral collisions as due to the deformation of while neither the neutron skin effect nor the nucleon-nucleon correlations result into a significant modification of this observable with respect to the traditional Woods-Saxon modeling. Our results suggest a significantly smaller CME signal to background ratio for the experimental charge separation measurement in peripheral collisions with the isobar systems than previously expected.
- Received 25 October 2019
- Revised 20 March 2020
- Accepted 26 May 2020
DOI:https://doi.org/10.1103/PhysRevC.101.061901
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