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Elliptic flow of charged hadrons in d+Au collisions at $\sqrt{s_{NN}} =$ 200 GeV using a multi-phase transport model

Jaideep Tanwar, Ishu Aggarwal, Vipul Bairathi, Lokesh Kumar, Sonia Kabana

TL;DR

This work investigates the elliptic flow $v_2$ of charged hadrons at mid-rapidity in $d$+$Au$ collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV using the AMPT model in both default and string-melting modes. By applying an $\eta$-sub event-plane method and comparing to a participant-plane reference, the study dissects the roles of early-stage partonic scattering and late-stage hadronic rescattering across $p_T$, centrality, and particle type, and contrasts results with STAR and PHENIX data. The findings show a strong $p_T$-dependent $v_2$ primarily shaped by partonic interactions (larger $\sigma_{qq}$ increases $v_2$; hadronic rescattering is less influential), with limited evidence for NCQ scaling and only mild mass ordering in identified hadrons. These results support the presence of partonic collectivity in a small, asymmetric system and highlight the importance of plane definitions and non-flow effects when interpreting $v_2$ in $d$+$Au$ at RHIC energies.

Abstract

This study presents a comprehensive analysis of the elliptic flow coefficient, $v_2$, for charged hadrons at mid-rapidity in d+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200\mathrm{~GeV}$. Utilizing the AMPT model in both default and string melting modes, we examine the dependence of $v_2$ on transverse momentum, collision centrality, and particle type. Furthermore, we present $v_2$ scaled by participant eccentricity, which indicates a similar level of collectivity across different centrality intervals in d+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200\mathrm{~GeV}$ within the AMPT-SM model. Our results indicate that the early-stage partonic phase significantly influences $v_2$, as observed by variations in parton scattering cross-section, while the later stage hadronic rescattering shows minimal impact. Comparisons with STAR and PHENIX experimental data show that the AMPT model effectively captures the transverse momentum dependence of $v_2$, underlining the importance of parton scattering mechanisms and the need for careful interpretation of experimental results in asymmetric systems.

Elliptic flow of charged hadrons in d+Au collisions at $\sqrt{s_{NN}} =$ 200 GeV using a multi-phase transport model

TL;DR

This work investigates the elliptic flow of charged hadrons at mid-rapidity in + collisions at GeV using the AMPT model in both default and string-melting modes. By applying an -sub event-plane method and comparing to a participant-plane reference, the study dissects the roles of early-stage partonic scattering and late-stage hadronic rescattering across , centrality, and particle type, and contrasts results with STAR and PHENIX data. The findings show a strong -dependent primarily shaped by partonic interactions (larger increases ; hadronic rescattering is less influential), with limited evidence for NCQ scaling and only mild mass ordering in identified hadrons. These results support the presence of partonic collectivity in a small, asymmetric system and highlight the importance of plane definitions and non-flow effects when interpreting in + at RHIC energies.

Abstract

This study presents a comprehensive analysis of the elliptic flow coefficient, , for charged hadrons at mid-rapidity in d+Au collisions at . Utilizing the AMPT model in both default and string melting modes, we examine the dependence of on transverse momentum, collision centrality, and particle type. Furthermore, we present scaled by participant eccentricity, which indicates a similar level of collectivity across different centrality intervals in d+Au collisions at within the AMPT-SM model. Our results indicate that the early-stage partonic phase significantly influences , as observed by variations in parton scattering cross-section, while the later stage hadronic rescattering shows minimal impact. Comparisons with STAR and PHENIX experimental data show that the AMPT model effectively captures the transverse momentum dependence of , underlining the importance of parton scattering mechanisms and the need for careful interpretation of experimental results in asymmetric systems.

Paper Structure

This paper contains 11 sections, 3 equations, 9 figures, 1 table.

Table of Contents

  1. Introduction
  2. Methodology
  3. AMPT model
  4. Flow Analysis Method
  5. Results
  6. Transverse momentum dependence of $v_2$
  7. Centrality dependence of $v_2$
  8. Particle type dependence of $v_2$
  9. Partonic and hadronic scattering dependence of $v_2$
  10. Summary and Conclusions
  11. Acknowledgments

Figures (9)

  • Figure 1: (Color online) Charged particle multiplicity distribution at mid-rapidity ($|\eta| < 0.9$) in d+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200\mathrm{~GeV}$ from the AMPT-SM model. Different bands show selection of 0-10%, 10-40%, and 40-80% collision centrality.
  • Figure 2: (Color online) Event plane angle resolution as a function of centrality using the $\eta$-sub event plane method in d+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200\mathrm{~GeV}$ from the AMPT-SM model.
  • Figure 3: (Color online) $v_2$ as a function of $p_\mathrm{T}$ for inclusive charged hadrons and identified hadrons at mid-rapidity in 0-80% central d+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200\mathrm{~GeV}$ from the AMPT-SM model. The statistical uncertainties are indicated by the error bars.
  • Figure 4: (Color online) $\sqrt{\langle\cos[2(\psi_{2}\lbrace{ep\rbrace} - \psi_{2}\lbrace{pp\rbrace}]\rangle}$ (%) as a function of centrality (%) in d+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200\mathrm{~GeV}$ from the AMPT-SM model.
  • Figure 5: (Color online) $v_2$ as function of $p_\mathrm{T}$ for inclusive charged and identified hadrons at mid-rapidity d+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200\mathrm{~GeV}$ from the AMPT-SM model. The statistical uncertainties are indicated by the error bars.
  • ...and 4 more figures