First-Order Event Plane Correlated Directed and Triangular Flow from Fixed-Target Energies at RHIC-STAR

Round 1

Reviewer 1 Report

In the paper entitled “First-order event plane correlated directed and triangular flow from fixed-target energies at RHIC-STAR”, the author has reported some interesting results. In particular, combined with the results at energies in collider experiments, the excitation function of anisotropic flow can be obatined. This paper is worth publishing after some revisions.

Some major comments:

Why not list all the figures for v_3, as there are much fewer figures for v_3 than for v_1?

Why not give the figures for v_2? It is better to compare the results for v_1, v_2, and v_3.

The author should give a systematic analysis for v_1, v_2, and v_3, so that a satisfactory conclusion on the dependence of energy and centrality can be made.

Some minor comments:

L31: “Quark-Gluon Plasma (QGP)” should be changed to QGP.

L47-48: “equation of state” should be chanegd to “Equation of State (EOS)”.

L60: “Equation of State (EOS)” should be chanegd to “EOS”

L65-66: Between the explanations for v_1 and v_3, why is there no the explanation for v_2 ?

L84-86: The definition of the O-xyz coordinate system should be given.

Author Response

1. During ISMD 2023, we did not include the centrality dependence of v3 in our presentation due to ongoing work on the pT differential measurements of v3. Additionally, it's noteworthy that the magnitude of v3 is relatively small compared to v1 and is accompanied by larger statistical uncertainties and fluctuations.  Considering all these factors, we have incorporated limited approved plots into our proceedings for v3.
2. We are engaged in the measurement of first event plane correlated directed (v1) and triangular flow (v3) at FXT energies. The analysis of elliptic flow (v2) is being conducted by other working groups. Therefore, the results from v2 measurements were not included in the presentation at ISMD 2023 and, consequently, are not added to this proceedings.
3. Other minor comments are addressed in the text 
4. Thank you very much for your valuable comments and suggestions. 

Reviewer 2 Report

This manuscript reports the measurement of the directed flow and triangular flow of identified hadrons in Au+Au collisions at low energies from STAR Collaboration. This is important to our field.  Before the manuscript's publication, it would be beneficial to add more discussions of how mean-field and baryon stopping factors influence the dv1/dy and dv3/dy, providing readers with a more comprehensive pictures on the physics involved.

Author Response

Thank you very much for your nice comments

1.  We have included more discussion in the text regarding baryon shadowing which is as follow: At low energies, the transit time ($\tau$) is comparable to the formation time of particles. Consequently, the spectators are not sufficiently distant from the collision volume, and the medium does not have the freedom to expand freely. This results in interactions between baryon-dominated spectator particles and the produced particles. Among the produced particles, pions, being one of the lightest, are particularly affected. The flow for $\pi^{+}$ is obstructed by the spectator particles, leading to a negative value for its $v_1$ slope. In contrast, $\pi^{-}$, influenced by Coulomb interactions from the baryons (protons), acquires a positive $v_1$ slope value. .

2. It has been observed that by inclusion of the baryonic mean-field, the JET AA Microscopic Transportation Model (JAM) reproduced the trends for v1 for baryons and mesons. The consistency of transport models  with baryonic mean-field for all measured baryons implies that the dominant degrees of freedom at low collision energies  are the interacting baryons. 

During ISMD 2023, this model comparison work was ongoing and was not part of the presentation, thus it was not included in the proceedings.

Reviewer 3 Report

This work concerns correlations in Au-Au collisions in the RHIC-STAR experiment. Many papers have already been published on this topic, and this work is not particularly original. However, the referee thinks it should be
 published because it was written for the proceedings of a conference.

Observations:
   1) Since it was written for proceedings, it should include "for the STAR collaboration" along with the author's name.
   2) Some quantities appear without clear definitions. For example, in the introduction on line 28, μb is mentioned, but it is not explained what it is.
   3)All figures exceed the text area.
    4) In the introduction, it is stated:
    "Many signatures of QGP formation and associated characteristics
    of the medium have been proposed. This proceeding will briefly
    explore one of the proposed signatures, namely, anisotropic flow."
    However, it seems that nothing is said about it in the conclusion.

Author Response

Thank you very much for your comments and suggestions

1. Yes we have updated author's name (for the STAR collaboration)
2. The text is modified according to the comment: clear definitions are provided for the quantities used in the text
3. Figures are adjusted in the updated version of script
4. Text is modified as per suggestion

Round 2

Reviewer 1 Report

In the revised manuscript and response, the author made appropriate modifications and explanations, and I think it can be published.