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dAu paper proposal

Updated on Thu, 2024-11-28 08:42. Originally created by iaggarwal on 2024-11-18 02:29.

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General Information :- 
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  • Paper Title : Multiplicity and Rapidity Dependence of (Multi-)strange hadron production in d+Au collisions at $\sqrt{\s_{NN}}$ = 200 GeV using the STAR detector 
  • PAs : Ishu Aggarwal, Lokesh Kumar 

                   Panjab University, Chandigarh-India 

  • Target Journal : Journal of High Energy Physics (JHEP)

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Abstract : 
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We present first measurement of (multi-)strange hadrons ($K_s^0}, $\Lambda$, $\bar\Lambda$, $\Xi^{-}$, $\bar\Xi^{+}$, $\Omega^{-}$ and    $\bar\Omega^{+}$) in d+Au collisions at $\sqrt{\s_{NN}}$ = 200 GeV, collected by STAR in 2016. The multiplicity and rapidity dependence of (multi-)strange hadron transverse momentum ($p_{T}$) spectra, $p_{T}$-integrated yields (dN/dy), average transverse momentum ($\langle p_{T} \rangle $), baryon to meson ratio, and yield ratios to pions is presented. A strangeness enhancement for these particles as compared to pp collisions is observed. Multiplicity dependence of these results along with pp, Cu+Cu and Au+Au collision systems at same energy suggest that the (multi-)strange hadron production follows a smooth trend and is independent of collision systems. The nuclear modification factor ($R_{dAu}$) and rapidity asymmetry ($Y_{Asym}$) as a function of transverse momentum is studied to look for the nuclear effects. The results are also compared with PYTHIA8/Angantyr and Heavy Ion Jet Interaction Generator (HIJING) models to understand the collision dynamics.

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Proposed Figures :-
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Figure 1 :
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Caption : Transverse momentum spectra for $K^0_s$, $\Lambda(\bar\Lambda)$, $\Xi^{-}(\bar\Xi^{+})$ and $\Omega^{-}(\bar\Omega^{+})$ at mid rapidity (|y| < 0.5) in d+Au collisions at $\sqrt{ \s_{NN}}$ = 200 GeV for two multiplicity classes (0-20% and 20-50%). Curves represent exponential fit function for $K^0_s$ and $\Lambda(\bar\Lambda)$, Boltzmann fit function for $\Xi^{-}(\bar\Xi^{+})$ and levy function for $\Omega^{-}(\bar\Omega^{+})$. The statistical and systematical uncertainties are shown as bars and boxes around the data points, respectively.  
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 Figure 2 :
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  Caption :  Integrated yield and mean transverse momentum as function of multiplicity for  $\pi^{-}(\pi^{+})$, $K^{-}(K^{+})$, $p(\bar{p})$, $K^0_s$, $\Lambda(\bar\Lambda)$, $\Xi^{-}(\bar\Xi^{+})$ and $\Omega$ at mid rapidity  in p+p, d+Au, Cu+Cu and Au+Au collisions at  $\sqrt{ \s_{NN}}$ = 200 GeV. The error bars shown are statistical and systematical uncertainties added in quadrature. Filled and open symbols are used for particle and anti particles respectively. 
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 Figure 3 :
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   Caption : Integrated yield ratio to pions as function of multiplicity for $K^{-}(K^{+})$, $p(\bar{p})$, $K^0_s$, $\Lambda(\bar\Lambda)$, $\Xi^{-}(\bar\Xi^{+})$ and $\Omega$ at mid rapidity  in p+p, d+Au, Cu+Cu and Au+Au collisions at  $\sqrt{\s_{NN}}$ = 200 GeV. The error bars shown are statistical and systematical uncertainties added in quadrature. Filled and open symbols are used for particles and anti particles respectively.
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 Figure 4 :
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   Caption : The enhancement factor for (multi-) strange particles $K^0_s$, $\Lambda(\bar\Lambda)$, $\Xi^{-}(\bar\Xi^{+})$ and $\Omega$ in d+Au, Cu+Cu and Au+Au collisions at $\sqrt{\s_{NN}}$ = 200 GeV at mid-rapidity. The green bars show the normalisation uncertainties. Statistical and systematical uncertainties are shown by bars and square brackets respectively.   
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 Figure 5 :
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    Caption :  $\Lambda / K^0_s$ as function of $p_{T}$ at mid rapidity (|y| < 0.5) for p+p, d+Au, Cu+Cu and Au+Au collisions at  $\sqrt{ \s_{NN}}$ = 200 GeV. Bars and square brackets are statistical and systematical errors respectively.
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 Figure 6 :
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    Caption : Nuclear modification factor (RdAu) for  $\pi^{-} + \pi^{+}$, $K^{-} + K^{+}$, $p + \bar{p}$, $K^0_s$, $\Lambda + \bar\Lambda$ and $\Xi^{-} + \bar\Xi^{+}$ at mid rapidity (|y| < 0.5) for 0-20% central d+Au collisions at $\sqrt{ \s_{NN}}$ = 200 GeV. The grey band corresponds to error due to uncertainties in estimating the number of binary collisions in 0-20% central d+Au collisions. Λ data points are pT shifted by 0.1 GeV/c for clarity. Bars and square brackets are statistical and systematical errors respectively.
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 Figure 7 :
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     Caption :  Transverse momentum spectra for $K^0_s$, $\Lambda(\bar\Lambda)$ and $\Xi^{-}(\bar\Xi^{+})$ for 0-20% multiplicity class in d+Au collisions at  $\sqrt{ \s_{NN}}$ = 200 GeV for rapidity regions (0 < |y| < 0.4 and 0.4 < |y| < 0.8). Curves represent exponential fit function for $K^0_s$ and $\Lambda(\bar\Lambda)$, Boltzmann fit function for  $\Xi^{-}(\bar\Xi^{+})$. The statistical and systematical uncertainties are shown as bars and boxes around the data points, respectively.  
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 Figure 8 :
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    Caption :  The pT-integrated yield (dN/dy) for  $K^0_s$, $\Lambda(\bar\Lambda)$ and $\Xi^{-}(\bar\Xi^{+})$ as a function of rapidity for 0-20% and 20-50% multiplicity classes in d+Au collisions at $\sqrt{ \s_{NN}}$ = 200 GeV. The statistical and systematical uncertainties are shown as bars and boxes around the data points, respectively. 
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Figure 9 : 
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     Caption :  The mean transverse momentum ($\langle p_{T} \rangle$) for  $K^0_s$, $\Lambda(\bar\Lambda)$ and $\Xi^{-}(\bar\Xi^{+})$ as a function of rapidity for 0-20% and 20-50% multiplicity classes in d+Au collisions at $\sqrt{ \s_{NN}}$ = 200 GeV. The statistical and systematical uncertainties are shown as bars and boxes around the data points, respectively.
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 Figure 10 :
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     Caption : Rapidity asymmetry ($Y_{Asym}$) for $K^{0}_{s}$, $\Lambda + \bar\Lambda$ and $\Xi^{-} + \bar\Xi^{+}$ as a function of $p_{T}$ in the rapidity range (0 < |y| < 0.4 and 0.4 < |y| < 0.8) for multiplicity classes in d+Au collisions at $\sqrt {\s_{NN}}$ = 200 GeV. The statistical uncertainties are shown as bars whereas the boxes represent the systematical uncertainties on the measurements.
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 Figure 11 : 
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    Caption :  The pT-integrated yield (dN/dy) for $K^0_s$, $\Lambda(\bar\Lambda)$ and $\Xi^{-}(\bar\Xi^{+})$ as a function of rapidity for 0-20% and 20-50% multiplicity classes in d+Au collisions at $\sqrt{ \s_{NN}}$ = 200 GeV. The statistical and systematical uncertainties are shown as bars and boxes around the data points, respectively. The experimental results are compared with PYTHIA8/Angantyr and HIJING models.
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 Figure 12 :
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      Caption :  The mean transverse momentum ($\langle p_{T} \rangle$) for  $K^0_s$, $\Lambda(\bar\Lambda)$ and $\Xi^{-}(\bar\Xi^{+})$ as a function of rapidity for 0-20% and 20-50% multiplicity classes in d+Au collisions at $\sqrt{ \s_{NN}}$ = 200 GeV. The statistical and systematical uncertainties are shown as bars and boxes around the data points, respectively. The experimental results are compared with PYTHIA8/Angantyr and HIJING models.
 
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Conclusions :
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  • Multiplicity and Rapidity Dependence of (Multi-)strange Hadron production in d+Au collisions at $\sqrt{ \s_{NN}}$  = 200 GeV using the STAR detector

  • Results suggest that d+Au system fills the gap between p+p and peripheral Cu+Cu and Au+Au collisions

  • Multiplicity dependence of particle production : 
    • Smooth transition particle production from p+p to A+A collisions
    • dN/dy increases a function of multiplicity, and follows common trend : Particle production seems to be independent of collision system
    • A hint of increase in $\langle p_{T} \rangle$  is observed as function of multiplicity
    • $\langle p_{T} \rangle$ is larger for heavier particles : Hint of radial flow

  • Strangeness enhancement : 

    • Strange particle yields scaled with average no. of nucleons are enhanced are compared to p+p collisions 
    • Yield ratio of particles to pions with more strangeness content decrease faster from high to low multiplicity

  • Baryon to Meson ratio :

    • $\Lambda / K^0_s$  in 0-20% d+Au at intermediate pT is larger comparable to p+p collisions
    • $\Lambda / K^0_s$  in central d+Au is comparable to A+A peripheral collisions

  • Nuclear modification factor (RdAu) : 

    • Cronin like enhancement is observed for  $K^0_S$, $\Lambda$ and $\Xi$  at intermediate pT
    • Enhancement is stronger for baryons ($\Xi$, $\Lambda$ and p) compared to mesons ($K^0_S$, $\pi$ )

  • Rapidity dependence of Particle production : 

    • dN/dy slightly decreases from negative (Au-going side) to positive (d-going side) rapidities for $K^0_s$, $\Lambda(\bar\Lambda)$ and $\Xi^{-}(\bar\Xi^{+})$
    • $\langle p_{T} \rangle$ is flat as function of rapidity for $K^0_s$, $\Lambda(\bar\Lambda)$ and $\Xi^{-}(\bar\Xi^{+})$ 
    • Rapidity asymmetry (YAsym), at low pT,  YAsym  >1, indicates the presence of nuclear effects 
    • Asymmetry is more pronounced for higher rapidity region and for heavier mass particles
  • Comparison of the data with models 
    • HIJING  and PYTHIA8/Angantyr explains the trend but both the models underestimates the yield for all the particles except for $K^0_s$ 
    • All the models explains the trend but underestimates the $\langle p_{T} \rangle$ values for all particles. 

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LFSUPC Working Group :
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   Paper proposal in LFSUPC (18 November 2024) : 
   https://drupal.star.bnl.gov/STAR/system/files/Paper_proposal_dAu.pdf

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Supporting Materials :
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LFS-UPC Presentations :
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Conference meeting and presentations :
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