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Baryon CF paper at 3 GeV

Updated on Fri, 2024-04-26 07:10. Originally created by fuchuan on 2022-07-26 06:54.

 Title: Measurements of Proton-Proton, Proton-Λ and Proton-Ξ- Correlation Functions in √s_NN= 3 GeV Au+Au Collisions at RHIC

 PAs: C. Fu, Z. Qin, Y.J. Zhou, X. Dong, X.F. Luo, K. Mi, Y.Q. Qi, S.S. Shi, Y.P. Wang, N. Xu, Z.G. Xiao

 Target journal : Physical Review Letters 
 Paper draft : In preparation
 Analysis note :
 p-p: https://drupal.star.bnl.gov/STAR/system/files/Proton_CF_note_v1.pdf
 p-Λ: https://drupal.star.bnl.gov/STAR/system/files/Analysis_Note_pLambda_QinZhi_v0_0.pdf
 p-Xi: https://drupal.star.bnl.gov/STAR/system/files/note_pXi_v1.pdf
 Paper proposal : https://drupal.star.bnl.gov/STAR/system/files/BaryonCF_3GeV_paper_proposal_04_05.pdf
 CVS codes on rcf: 

Outline

  1.   Abstract
  2.   Motivation
  3.   Figures
  4.   Summary
  5.   Supporting-materials
  6.  Questions-in-PWGC-preview

Abstract
Important spatiotemporal extension and the final state interaction (FSI) parameters can be extracted from the measurements of two-particle correlations from high-energy nuclear collisions.
It is well known that the interaction information of nucleon-nucleon, e.g. proton−proton (p-p), and proton-Λ (p-L), are basic ingredients for studying the inner structure of compact stars.
In this paper, we report the first results of baryon correlation functions (CF) for the pairs of p-p, p-L and p−Ξ- from 3 GeV Au+Au collisions at RHIC.
The data was taken with the fixed-target mode by the STAR experiment.
Lednický-Lyuboshitz model is used to extract the baryon source sizes (RG) and the FSI parameters (f0, d0) as a function of collision centrality and rapidity, for the first time, from heavy ion collisions.
While the RG shows a clear centrality dependence, the f0 and d0 are found independent of either centrality nor rapidity. 
A hadronic transport model UrQMD plus afterburner (CRAB) is used to simulate the CF.

 

Motivation
The CF is sensitive to the source size and Final State Interaction.
It is important to extract baryon source size and Final State Interaction parameters.


Figures

Fig. 1: The density distributions in transverse momentum (pT) and particle rapidity (y) for proton (a), Λ (b) and Ξ- (c) in √s_NN= 3 GeV Au+Au collisions.
The p < 2 GeV/c cut is applied in proton selection by TPC. Correlation functions are measured in the pT-y regions shown by the box. 



 

Fig. 2: The invariant-mass distributions of reconstructed Λ (a) and Ξ- (b) in √s_NN= 3 GeV Au+Au collisions. The candidates are selected within two gray lines.


Fig. 3: Collision centrality dependence of the correlation functions for mid-rapidity (−0.5 < y < 0) pairs of p−p (left panel) and p−Λ (middle panel) from √s_NN = 3 GeV Au+Au collisions.
For p−Ξ- (right panel) correlation function, only 0-60% result is available due to the limitation in statistics.
Symbols, solid lines and dashed lines represent the results from experiment, Lednický-Lyuboshitz (LL) model fit and UrQMD model calculation, respectively.
Vertical bars and bands on data points represent statistical and systematic uncertainties,  respectively.  

 

 


Fig. 4: Left panel: Mid-rapidity (-0.5 < y < 0) source size parameter rG as a function of collision centrality for p-p and p−Λ pairs from 3 GeV Au+Au collisions.
Solid and open symbols represent the results from data and UrQMD, respectively. Bands represent the half of RMS values of relative distance between two particles extracted from UrQMD.
Verticle lines on data points represent combined stat. and sys. uncerntainty (smaller than symbol and invisible for p-p). Right panel: Strong interaction parameters (d0 vs. f0) for p-p, p−Λ pairs. Solid circles and open triangles represent data points and theoretical values, respectively. Red lines are 1-σ contour for p-p (smaller than symbol and invisible) and p−Λ pair, respectively.

 

Table 1: Source-size extracted from data and UrQMD for p-p (left) and p−Λ (right) pair from different centrality and rapidity bins.

     

Table 2: f0 and d0 extracted from p-p CFs from different centrality and rapidity bins.

 
Summary
We report the first results of collision centrality and rapidity dependence of baryon correlation functions for p-p, p-Λ and p-Ξ- pairs from √s_NN= 3 GeV Au+Au collisions at RHIC. 
Source size parameter rG, scattering length f0 and effective range d0 for the pairs of p-p and p-Λ are extracted from different collision centrality and rapidity bins. 
The rG varies with centrality and rapidity, and it is larger for more central collisions and for p-Λ pair. On the other hand, both values of f0 and d0 do not show any visible centrality and rapidity dependence. 
The spin singlet value of strong interaction parameters (f0, d0) are (7.07 +- 0.02 fm, 3.74 +- 0.04 fm) for p-p pair, and the spin-averaged values of (f0, d0) are (2.32 +- 0.12 fm, 3.54 +- 1.97 fm) for p-Λ pair.
These values are also found to be consistent with data from 200 GeV collisions. 

Supporting-materials
https://drupal.star.bnl.gov/STAR/system/files/Proton_CF_PWG_1217.pdf
https://drupal.star.bnl.gov/STAR/system/files/Proton_CF_CollaborationMeeting_Chuan_0916_v2.pdf
https://drupal.star.bnl.gov/STAR/system/files/Proton_CF_PWG_Chuan_1216.pdf
https://drupal.star.bnl.gov/STAR/system/files/ppCF_sys_PWG_Chuan_2022_0414.pdf
https://drupal.star.bnl.gov/STAR/system/files/ppCF_LLfit_PWG_05-18.pdf
https://drupal.star.bnl.gov/STAR/system/files/LambdaProton_CF_QinZhi_20220714.pdf

 

https://drupal.star.bnl.gov/STAR/system/files/pLambda_CF_Zhi_PWG20230601.pdf

https://drupal.star.bnl.gov/STAR/system/files/pXi_CorrelationFunction_qm22poster_v5.pdf

Questions-in-PWGC-preview

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