Global Lambda polarization in Au+Au collisions at 3 GeV
Updated on Fri, 2022-01-14 13:01. Originally created by adams92 on 2020-04-15 21:30.
Primary Authors
Joseph R. Adams, Kosuke Okubo, Michael Lisa, and ShinIchi Esumi
Title
Global $\Lambda$ polarization in Au+Au collisions at $\sqrt{\mathrm{NN}} = 3$ GeV
Abstract
(see attachment)
Target Journal
Physical Review C Letters (PRC Lett.)
According to the APS length guide, a PRL has max size 3750 and PRC Letter has 4500. This paper's total word count (words + equations + images) is estimated to be 4120, so the length is more appropriate for a PRC Letter. Another reason to make it PRC Letter is that it has 6 figures, which is commensurate with other PRC Letters (which sometimes have fewer, but they are huge multi-panel things, and also have tables). Yet another reason is that this paper is on the more technical side.
Responses to Institutional-Review Comments
See attachment
Figures
Figure 1
Figure 4
Figure 5
Figure 6
Conclusions
See attachments
Code(Analysis Note ID: PSN0767)
All of the code exists in public GitHub repositories; I make "picoDst"s on RCF containing basic event information and do the rest of my analysis locally on my laptop. The repositories are:
RCF
Local
These repositories are private, so please email me at adams.1940@osu.edu or joseph.r.adams92@gmail.com if you'd like access.
Presentations
Bulk Corr PWG Meeting presentations:
Joseph R. Adams, Kosuke Okubo, Michael Lisa, and ShinIchi Esumi
Title
Global $\Lambda$ polarization in Au+Au collisions at $\sqrt{\mathrm{NN}} = 3$ GeV
Abstract
(see attachment)
Global hyperon polarization, $\PHyper$, in Au+Au collisions over a large range of collision energy, $\sNN$, has recently been measured and successfully reproduced by hydrodynamic and transport models with intense fluid vorticity of the Quark-Gluon Plasma (QGP). While na\"{i}ve extrapolation of data trends suggests a large $\PHyper$ as the collision energy is reduced, the behavior of $\PHyper$ at small $\sNN<7.7$~GeV is unknown. Operating the STAR experiment in fixed-target mode, we have measured the polarization of $\Lambda$ hyperons along the direction of global angular momentum in Au+Au collisions at $\sNN=3$ GeV. The observation of substantial polarization of $4.91\pm0.82(\rm stat.)\pm0.15(\rm syst.)$\% in these collisions may require a reexamination of the viscosity of any fluid created in the collision, the thermalization timescale of rotational modes, and of hadronic mechanisms to produce global polarization.
Target Journal
Physical Review C Letters (PRC Lett.)
According to the APS length guide, a PRL has max size 3750 and PRC Letter has 4500. This paper's total word count (words + equations + images) is estimated to be 4120, so the length is more appropriate for a PRC Letter. Another reason to make it PRC Letter is that it has 6 figures, which is commensurate with other PRC Letters (which sometimes have fewer, but they are huge multi-panel things, and also have tables). Yet another reason is that this paper is on the more technical side.
Responses to Institutional-Review Comments
See attachment
Figures
Figure 1Figure 4Figure 5Figure 6Conclusions
- Non-zero global $\Lambda$ polarization, $\bar{P}_{\Lambda}$, is measured in Au+Au collisions at $\sqrt{\mathrm{NN}} = 3$ GeV with significance 6$\sigma$.
- The measured polarization is found to be consistent with the trend suggested by previous measurements and models in which polarization decreases with $\sqrt{\mathrm{NN}}$.
- The magnitude of $\bar{P}_{\Lambda}$ indicates extremely large vorticities present in low-energy heavy-ion collisions.
- With the uncertainties, there is no observable dependence of $\bar{P}_{\Lambda}$ on $p_{\mathrm{T}}$ or $y$.
- The lack of rapidity dependence is striking given the abundance of model predictions of significant dependence; with our unique acceptance of even the most forward $\Lambda$s at $\sqrt{\mathrm{NN}}=3$ GeV, we would be able to see such dependence.
- We see dependence of $\bar{P}_{\Lambda}$ on centrality, consistent with previous observations and with the expectations of an angular-momentum driven effect.
See attachments
Code(Analysis Note ID: PSN0767)
All of the code exists in public GitHub repositories; I make "picoDst"s on RCF containing basic event information and do the rest of my analysis locally on my laptop. The repositories are:
RCF
Local
These repositories are private, so please email me at adams.1940@osu.edu or joseph.r.adams92@gmail.com if you'd like access.
Presentations
Bulk Corr PWG Meeting presentations:
- 21 November 2018 - Analysis Meeting (using fast offline)
- 5 December 2018 (dataset QA) (slides)
- 15 April 2019 (using fast offline): "Lambda Polarization at Fixed-Target Energies in Au+Au Collisions" (slides)
- 12 February 2020 (using full dataset)
- 12 March 2020 - Collaboration Meeting (using full dataset)
- 25 March 2020: "Lambda Polarization at 3 GeV" (slides)
- 1 April 2020: "Lambda Polarization at 3 GeV" (slides)
- 15 April 2020: "Lambda Polarization at 3 GeV" (slides)
- 8 May 2020 (preview)
- 27 May 2020 (preview-based changes) (slides)
- 3 June 2020 (identifying P ̅_Λ^obs(m_inv.) problem, driven by AEE) (slides)
- 8 July 2020 (solving P ̅_Λ^obs(m_inv.) problem) (slides)
- 17 September 2020 (checks for systematic mistakes) (slides)
- 3 February 2021 (GPC request) (slides)
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