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Register a new userSignatures of $alpha$ clustering in $^{16}$O by using a multiphase transport model
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$alpha$-clustered structures in light nuclei could be studied through snapshots taken by relativistic heavy-ion collisions. A multiphase transport (AMPT) model is employed to simulate the initial structure of collision nuclei and the proceeding collisions at center of mass energy $sqrt{s_{NN}}$ = 6.37 TeV. This initial structure can finally be reflected in the subsequent observations, such as elliptic flow ($v_{2}$), triangular flow ($v_{3}$) and quadrangular flow ($v_4$). Three sets of the collision systems are chosen to illustrate system scan is a good way to identify the exotic $alpha$-clustered nuclear structure, case I: $mathrm{^{16}O}$ nucleus (with or without $alpha$-cluster) + ordinary nuclei (always in Woods-Saxon distribution) in most central collisions, case II: $mathrm{^{16}O}$ nucleus (with or without $alpha$-cluster) + $mathrm{^{197}Au}$ nucleus collisions for centrality dependence, and case III: symmetric collision systems (namely, $^{10}$B + $^{10}$B, $^{12}$C + $^{12}$C, $^{16}$O + $^{16}$O (with or without $alpha$-cluster), $^{20}$Ne + $^{20}$Ne, and $^{40}$Ca + $^{40}$Ca) in most central collisions. Our calculations propose that relativistic heavy-ion collision experiments at $sqrt{s_{NN}}$ = 6.37 TeV are promised to distinguish the tetrahedron structure of $mathrm{^{16}O}$ from the Woods-Saxon one and shed lights on the system scan projects in experiments.
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Within a multi-phase transport model with string melting scenario, jet transport parameter $hat{q}$ is calculated in Au+Au collisions at $sqrt{s_{NN} } $= 200 GeV and Pb+Pb collisions at $sqrt{s_{NN} } $= 2.76 TeV. The $hat{q}$ increases with the increasing of jet energy for both partonic phase and hadronic phase. The energy and path length dependences of $hat{q}$ in full heavy-ion evolution are consistent with the expectations of jet quenching. The correlation between jet transport parameter $hat{q}$ and dijet transverse momentum asymmetry $A_{J}$ is mainly investigated, which discloses that a larger $hat{q}$ corresponds to a larger $A_{J}$. It supports a consistent jet energy loss picture from the two viewpoints of single jet and dijet. It is proposed to measure dijet asymmetry distributions with different jet transport parameter ranges as a new potential method to study jet quenching physics in high energy heavy-ion collisions.
Collisions of light and heavy nuclei in relativistic heavy-ion collisions have been shown to be sensitive to nuclear structure. With a proposed $^{16}mathrm{O}^{16}mathrm{O}$ run at the LHC and RHIC we study the potential for finding $alpha$ clustering in $^{16}$O. Here we use the state-of-the-art iEBE-VISHNU package with $^{16}$O nucleonic configurations from {rm ab initio} nuclear lattice simulations. This setup was tuned using a Bayesian analysis on pPb and PbPb systems. We find that the $^{16}mathrm{O}^{16}mathrm{O}$ system always begins far from equilibrium and that at LHC and RHIC it approaches the regime of hydrodynamic applicability only at very late times. Finally, by taking ratios of flow harmonics we are able to find measurable differences between $alpha$-clustering, nucleonic, and subnucleonic degrees of freedom in the initial state.
Jet-medium interaction involves two important effects: jet energy loss and medium response. The search for jet-induced medium excitations is one of the hot topics in jet quenching study in relativistic nuclear collisions. In this work, we perform a systematic study on how the lost energy from hard jets evolves with the bulk medium and redistributes in the final state of heavy-ion collisions via a multi-phase transport model. In particular, the ($Delta eta, Delta phi$) distribution of charged particles with respect to the jet axis and jet shape function are studied for various Pb+Pb collision centralities and for different transverse momentum intervals of charged particles. Our numerical result shows a strong enhancement of soft particles at large angles for Pb+Pb collisions relative to p+p collisions at the LHC, qualitatively consistent with recent CMS data. This indicates that a significant fraction of the lost energy from hard jets is carried by soft particles at large angles away from the jet axis.
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The chiral magnetic effect (CME) induces an electric charge separation in a chiral medium along the magnetic field that is mostly produced by spectator protons in heavy-ion collisions. The experimental searches for the CME, based on the charge-dependent angular correlations ($gamma$), however, have remained inconclusive, because the non-CME background contributions are not well understood. Experimentally, the $gamma$ correlators have been measured with respect to the second-order ($Psi_{2}$) and the third-order ($Psi_{3}$) symmetry planes, defined as $gamma_{112}$ and $gamma_{123}$, respectively. The expectation was that with a proper normalization, $gamma_{123}$ would provide a data-driven estimate for the background contributions in $gamma_{112}$. In this work, we calculate different harmonics of the $gamma$ correlators using a charge-conserving version of a multiphase transport (AMPT) model to examine the validity of the said assumption. We find that the pure-background AMPT simulations do not yield an equality in the normalized $gamma_{112}$ and $gamma_{123}$, quantified by $kappa_{112}$ and $kappa_{123}$, respectively. Furthermore, we test another correlator, $gamma_{132}$, within AMPT, and discuss the relation between different $gamma$ correlators.
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