Search

Recently, the rapidity-odd directed flow ( v 1 ) of produced hadrons ( K − , ϕ , p ¯ , Λ ¯ , Ξ ¯ + , Ω − , and Ω ¯ + ) has been studied. Several combinations of these produced hadrons, with very small mass differences but differences in the net electric charge ( Δ q ) and net strangeness ( Δ S ) on the two sides, have been considered. A difference in v 1 between the two sides of these combinations ( Δ v 1 ) has been proposed as a consequence of the electromagnetic field produced in relativistic heavy-ion collisions, especially if Δ v 1 increases with Δ q . Our study is performed to understand the effect of the coalescence sum rule (CSR) on Δ v 1 . We point out that the CSR leads to Δ v 1 = c q Δ q + c S Δ S , where the coefficients c q and c S reflect the Δ v 1 of produced quarks. Equivalently, one can write Δ v 1 = c q Δ q + c B Δ B , involving the difference in the net baryon number Δ B , where the CSR gives c B = − 3 c S . We then propose two methods to extract the coefficients for the Δ q and Δ S dependences of Δ v 1 . [ABSTRACT FROM AUTHOR]

We use the string melting version of a multi-phase transport (AMPT) model to study Cu+Au collisions at s NN = 200 GeV. The rapidity distributions of identified hadrons show asymmetric dependences on rapidity. In addition, elliptic and triangular flows at mid-rapidity from the AMPT model for pions, kaons, and protons agree reasonably with the experimental data up to p T ∼ 1 GeV/c. We then investigate the forward/backward asymmetry of v 2 and v 3 . We find that these anisotropic flows are larger on the Au-going side than the Cu-going side, while the asymmetry tends to go away in very peripheral collisions. We also make predictions on transverse momentum spectra of identified hadrons and longitudinal decorrelations of charged particles, where the average decorrelation of elliptic flow in asymmetric Cu+Au collisions is found to be stronger than that in Au+Au collisions. [ABSTRACT FROM AUTHOR]

The rapidity-odd directed flows (v 1) of identified hadrons are expected to follow the coalescence sum rule when the created matter is initially in parton degrees of freedom and then hadronizes through quark coalescence. A recent study has considered the v 1 of produced hadrons that do not contain u or d constituent quarks. It has constructed multiple hadron sets with a small mass difference but given difference in electric charge Δ q and strangeness Δ S between the two sides, where a nonzero and increasing Δ v 1 with Δ q has been proposed to be a consequence of electromagnetic fields. In this study, we examine the consequence of coalescence sum rule on the Δ v 1 of the hadron sets in the absence of electromagnetic fields. We find that in general Δ v 1 ≠ 0 for a hadron set with nonzero Δ q and/or Δ S due to potential v 1 differences between u ¯ and d ¯ and between s and s ¯ quarks. We further propose methods to extract the coefficients for the Δ q - and Δ S -dependences of the direct flow difference, where a nonzero constant term would indicate the breaking of the coalescence sum rule. The extraction methods are then demonstrated with transport model results. [ABSTRACT FROM AUTHOR]

Using a multiphase transport model, we study the production of multistrange (anti)baryons from the hadronic matter formed in relativistic heavy ion collisions. The mechanism we introduce is the strangeness-exchange reactions between antikaons and hyperons for strange particle production and between kaons and antihyperons for strange antiparticle production. We find that these reactions contribute significantly to the production of multistrange baryons and antibaryons in heavy ion collisions at SPS energies, which has been found to be appreciably enhanced. We have also made predictions for multistrange baryon and antibaryon production in heavy ion collisions at RHIC and found a similar enhancement. The (anti)particle mass dependence of inverse slope parameters extracted from their transverse mass spectra in the transport model exhibit similar trend as in the available experimental data at both SPS and RHIC energies. [Copyright &y& Elsevier]

It has been a challenge to understand the experimental data on both the nuclear modification factor and elliptic flow of D 0 mesons in p −Pb collisions at LHC energies. In this work, we study these collisions with an improved multi-phase transport model. By including the independent fragmentation and a significant Cronin effect (i.e., transverse momentum broadening) for charm quarks, we provide the first simultaneous description of the D 0 meson R pA and v 2 data at p T ≤ 8 GeV/ c. The model also reasonably describes the D 0 meson p T spectra and the low- p T charged hadron spectra, R pA and v 2. Our results show that both parton interactions and the Cronin effect are important for the D 0 meson R pA , while parton interactions are mostly responsible for the D 0 meson v 2. It is thus essential to include the Cronin effect for the simultaneous description of the D 0 meson R pA and v 2. This work implies that the Cronin effect could also be important for heavy hadrons in large systems. [ABSTRACT FROM AUTHOR]

Predictions for cold nuclear matter effects on charged hadrons, identified light hadrons, quarkonium and heavy flavor hadrons, Drell–Yan dileptons, jets, photons, gauge bosons and top quark pairs produced in p +Pb collisions at s N N = 8.16 TeV are compiled and, where possible, compared to each other. Predictions of the normalized ratios of p +Pb to p + p cross sections are also presented for most of the observables, providing new insights into the expected role of cold nuclear matter effects. In particular, the role of nuclear parton distribution functions on particle production can now be probed over a wider range of phase space than ever before. [ABSTRACT FROM AUTHOR]

Double strangeness Ξ − production in Au+Au collisions at 2, 4, and 6 GeV/nucleon incident beam energies is studied with the pure hadron cascade version of a multi-phase transport model. It is found that due to larger nuclear compression, the model with the soft equation of state (EoS) gives larger yields of both single strangeness (K + and Λ + Σ 0) and double strangeness Ξ −. The sensitivity of the double strangeness Ξ − to the EoS is evidently larger than that of K + or Λ + Σ 0 since the phase-space distribution of produced Ξ − is more compact compared to those of the single strangeness. The larger sensitivity of the yields ratio of Ξ − to the EoS from heavy and light systems is kept compared to that of the single strangeness. The study of Ξ − production in relativistic heavy-ion collisions provides an alternative for the ongoing heavy-ion collision program at facilities worldwide for identifying the EoS at high densities, which is relevant to the investigation of the phase boundary and onset of deconfinement of dense nuclear matter. [ABSTRACT FROM AUTHOR]