Download presentation
Presentation is loading. Please wait.
1
Resolution of Several Puzzles at Intermediate p T and Recent Developments in Correlation Rudolph C. Hwa University of Oregon Quark Matter 05 Budapest, Hungary, August 2005
2
2 Work done in collaboration with Chunbin Yang (Hua-Zhong Normal University, Wuhan) Rainer Fries (University of Minnesota) Zhiguang Tan (Hua-Zhong Normal University, Wuhan) Charles Chiu (University of Texas, Austin)
3
3 Puzzles at intermediate p T 1.Proton/pion ratio 2.Azimuthal anisotropy 3.Cronin effect in pion and proton production 4.Forward-backward asymmetry in dAu collisions 5.Same-side associated particle distribution QM04
4
4 Puzzle #1 R p/π 1 Not possible in fragmentation model: R p/π u
5
5 inclusive distribution of pions in any direction soft component thermal-shower recombination usual fragmentation (by means of recombination) Proton formation: uud distribution In the recombination model
6
6 production in AuAu central collision at 200 GeV Hwa & CB Yang, PRC70, 024905 (2004) fragmentation thermal
7
7 All in recombination/ coalescence model compilation by R.Seto (UCR)
8
8 Molnar and Voloshin, PRL 91, 092301 (2003). Parton coalescence implies that v 2 (p T ) scales with the number of constituents STAR data Puzzle #2 Azimuthal anisotropy
9
9 Puzzle #3 in pA or dA collisions k T broadening by multiple scattering in the initial state. Unchallenged for ~30 years. If the medium effect is before fragmentation, then should be independent of h= or p Cronin Effect Cronin et al, Phys.Rev.D (1975) p q h A STAR, PHENIX (2003) Cronin et al, Phys.Rev.D (1975) p >
10
10 R CP for d-Au collisions because 3q p, 2q more partons at 1/3 than at 1/2 Argument does not extend to, nor to higher p T because of ST and SS recombination. Hwa & CB Yang, PRL 93, 082302 (04). PRC 70, 037901 (04).
11
11 Puzzle #4 Forward-backward asymmetry in d+Au collisions Expects more forward particles at high p T than backward particles If initial transverse broadening of parton gives hadrons at high p T, then backward has no broadening forward has more transverse broadening B/F < 1
12
12 Backward-forward ratio at intermed. p T in d+Au collisions (STAR) B/F
13
13 Hwa, Yang, Fries, PRC 71, 024902 (2005) Forward production in d+Au collisions Underlying physics for hadron production is not changed from backward to forward rapidity. BRAHMS data
14
14 STAR : nucl-ex/0501016 Trigger 4 < p T < 6 GeV/c Puzzle #5: Associated particle pT distribution (near side) factor of 3 difficult for medium modification of fragmentation function to achieve Hwa & Tan, nucl-th/0503060 Recombination model because of T-S recombination
15
15 PHENIX (preliminary) STAR (preliminary) N. Grau J. Bielcikova RIKEN/BNL Workshop 3/05
16
16 Correlations 1.Correlation in jets: distributions in and 2. Two-particle correlation without triggers 3. Autocorrelations 4. Away-side distribution (jet quenching)
17
17 and distributions P1P1 P2P2 Pedestal Why? Are these peaks related? How?
18
18 For STST recombination enhanced thermal trigger associated particle with background subtracted Pedestal peak in &
19
19 Chiu & Hwa, nucl-th/0505014 pedestal T=15 MeV
20
20 Chiu & Hwa, nucl-th/0505014
21
21 Correlation without triggers Correlation function Normalized correlation function
22
22 Correlation of partons in jets A. Two shower partons in a jet in vacuum Fixed hard parton momentum k (as in e+e- annihilation) k x1x1 x2x2 kinematically constrained dynamically uncorrelated
23
23 no correlation Hwa & Tan, nucl-th/0503052 0
24
24 Correlation of pions in jets Two-particle distribution k q3q3 q1q1 q4q4 q2q2 The shower partons are anti-correlated
25
25 Hwa and Tan, nucl-th/0503052
26
26
27
27 Hwa and Tan, nucl-th/0503052
28
28 Autocorrelation Correlation function 1,2 on equal footing --- no trigger Define Autocorrelation: Fix and, and integrate over all other variables in The only non-trivial contribution to near, would come from jets
29
29 p2p2 p1p1 x y z 11 22 pion momentum space q2q2 q1q1 x y z 22 11 k parton momentum space -- P( ) Gaussian in jet cone
30
30 Chiu and Hwa (05)
31
31 Away-side distribution
32
32 Random walker on a circular mount Most walks are absorbed inside the medium Step size depends on local density Direction of walk is random within a Gaussian peak
33
33 Sample tracks those that emergethose that are absorbed away-side distribution Chiu & Hwa work in progress
34
34 Conclusion Hadronization by recombination resolves several puzzles at intermediate pT. The pedestal and peak structure in the near-side jets is due to enhanced thermal partons and to jet cone structure of shower partons. A dip is predicted in the correlation function due to anti-correlation among the shower partons. Promising start made in the distribution on the away-side by simulating parton rescattering and absorption.
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.