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Effect of πKp from d+Au Collisions at 200 GeV

This study analyzes the Cronin effect in d+Au collisions at 200 GeV, comparing the production of π, K, and p. It investigates whether the effect is due to initial or final-state interactions. The results are compared with recombination models and show a mass dependence of the Cronin effect. The study also explores the centrality dependence and integral yield RdAu.

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Effect of πKp from d+Au Collisions at 200 GeV

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  1. Cronin Effect of K p from d+Au Collisions at 200 GeV Lijuan Ruan USTC/BNL Outline: • Introduction and Motivation • Physics Results and Discussions • Summary and Outlook • Thanks: STAR Collaboration CCAST Workshop, 2004

  2. Cronin Data at Lower Energy J.W. Cronin et al., PRD 11, 3105 (1975); • Enhancement of hadron production in proton-nucleus collisions. • R>1 at high pT. • Explained by initial multiple scattering. Cronin effect larger for protons compared to pions CCAST Workshop, 2004

  3. Cronin Effect at Lower Energy P.B. Straub et al., PRL 68, 452 (1992) Cronin effect decrease with energy CCAST Workshop, 2004

  4. Some Definitions Initial-state effect: The effect happens before the hard scattering. Final-state effect: The effect happens after or at the hard scattering. CCAST Workshop, 2004

  5. A. Accardi, hep-ph/0212148 Px~1 GeV/c 1 <RM<2 , 2.5<PM<4.5 GeV/c Model Prediction:Initial Multiple Parton Scattering X.N. Wang, nucl-th/0303004 Initial multiple parton scattering can reproduce Cronin Effect of the charge hadron. IMPS+jet quenching can reproduce the suppression of the charge hadron in Au+Au collisions. CCAST Workshop, 2004

  6. Centrality Dependence: Rcp in Au+Au nucl-ex/0306007, STAR Collaboration IMPS+jet quenching will result in the same suppression of baryon/meson in Au+Au collisions. Baryons () increase faster than mesons (Ks, K) from peripheral to central collisions; Baryon:~ Nbin scaling CCAST Workshop, 2004

  7. Centrality Dependence: Rcp in Au+Au R.J. Fries, et al.,nucl-th/0306027 Recombination models: q q proton q q Ks qbar Recombination models predict that a scale according to the number of constituent quarks in a hadron seems to govern the particle production at intermediate pT. CCAST Workshop, 2004

  8. Measure the Cronin effect of pion/proton. • Compare with recombination model • How about the eta asymmetry of Cronin effect? • Cronin effect is initial state or final state effect? Motivation • Initial multiple parton scattering can reproduce Cronin Effect of the charge hadron. • IMPS+independent Fragmentation will result in the same Cronin Effect of pion and proton. • IMPS predict that the Cronin effect on deuteron side is larger than that on Au side at forward rapidity. • X.N. Wang, nucl-th/0303004 Recombination models can produce the Rcp of baryon/meson at intermediate pT in AuAu collisions CCAST Workshop, 2004

  9. MRPC-TOFr PID plot Hadron PID proton:3GeV/c kaon: 1.6GeV/c nucl-ex/0309012 CCAST Workshop, 2004

  10. Spectra from 200GeV d+Au, p+p STAR Collaboration, nucl-ex/0309012 d+Au MinBias: 95%3% of total nuclear cross section p+p NSD : 30.0 3.5 mb, spectra correction <5% to inelastic CCAST Workshop, 2004

  11. Spectra in 3 centrality bin central peripheral • The spectra in d+Au collisions are harder than those in p+p collisions CCAST Workshop, 2004

  12. Cronin Effect:  K p RdAu • Low pT, RdAu <1 • High pT, RdAu >1 • Px~=1 GeV/c • RdAu(p)> RdAu(,K) • RdAu of protons rises • faster than those of • pions and kaons. • Proton spectra at • intermediate pT : no • binary scaling STAR Collaboration, nucl-ex/0309012 Characteristic Cronin Effect CCAST Workshop, 2004

  13. The Ratios between p+pbar and h STAR Collaboration, nucl-ex/0309012 • d+Au: (pbar+p)/h=0.240.01 0.01 (2<PT<3 GeV/c) • p+p: (pbar+p)/h=0.210.02 0.01 (2<PT<3 GeV/c) • p-=0.041 0.01 0.006 (1.2<PT<3 GeV/c), • lower energy sqrt(s)~30 GeV/c, p-=0.0950.004 • (pbar+p)/h=0.24,A factor of 2 smaller than that in Au+Au  AuAu baryon excess due to Final State Effect. CCAST Workshop, 2004

  14. Model Comparison: recombination Recombination model can reproduce the  spectra in d+Au collisions. Great Thanks to C.B. Yang (CCNU)! R.C. Hwa et al., nucl-th/0403001; R.C. Hwa et al., nucl-th/0406066 CCAST Workshop, 2004

  15. Model Comparison: recombination Recombination model can reproduce the p spectra in d+Au collisions. Great Thanks to C.B. Yang (CCNU)! R.C. Hwa et al., nucl-th/0403001; R.C. Hwa et al., nucl-th/0406066 CCAST Workshop, 2004

  16. Integral Yield RdAu • Integral yield RdAu is smaller than 1: • - Shadowing effect ? • - Mass dependent ? • The integral yield RdAu is bigger for proton than for pion. CCAST Workshop, 2004

  17. Cronin Effect  Asymmetry This model, initial multiple parton scattering alone, can’t reproduce the eta asymmetry of Cronin effect. Hwa et al. claims they can do it. X.N. Wang, nucl-th/0303004 CCAST Workshop, 2004

  18. Conclusions • RdAu of protons rises faster than those of pions andkaons at 200 GeV d+Au collisions, Characteristic Cronin Effect. • The mass dependence of Cronin effect at RHIC energy is much smaller than that at lower energy. • Recombination model can reproduce the Cronin Effect of , p Final State Effect. • Baryon enhanced p/h (dAu/pp)=1.19 0.05 0.03. In Au+Au, the ratio is about a factor of 2 higher Final State Effect. • Initial multiple parton scattering can reproduce Cronin Effect of the charge hadron. • IMPS + independent fragmentation will result in the same Cronin Effect of pion and proton. • The model, based on initial multiple parton scattering, can’t reproduce the measured rapidity asymmetry. Cronin Effect is not the initial-state effect only, the final-state effect plays an important role. CCAST Workshop, 2004

  19. Outlook Coherent multiple parton scattering:for a nucleus, if x<xc/A1/3~0.1/A1/3, the probe cannot tell which nucleon the parton comes from. 2 3 1 PT(GeV/c) J.W. Qiu et al., hep-ph/0309094; J.W. Qiuet al., hep-ph/0405068 Coherent multiple parton scattering may shed light on the physics of Cronin effect. CCAST Workshop, 2004

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