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SQM 2007, Levoča, Slovakia. Strange Particle Ratios on the Near- & Away-Sides of Jets at RHIC. Jiaxu Zuo Shanghai Institute of Applied Physics & BNL (For STAR Collaboration). Outline. Motivation Analysis Method Results & Discussions Summary. STAR Au+Au 200GeV Year 2004 Running Data - PowerPoint PPT Presentation
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1STARSTAR
Strange Particle Ratios on the Near- & Away-Sides of
Jets at RHIC
Jiaxu Zuo Shanghai Institute of Applied Physics & BNL
(For STAR Collaboration)
SQM 2007, Levoča, SlovakiaSQM 2007, Levoča, Slovakia
2STARSTAR
Outline
• Motivation
• Analysis Method
• Results & Discussions
• Summary
• STAR Au+Au 200GeV Year 2004 Running Data
• ~13M Events
3STARSTAR
Di-hadron correlations
For high pT: away-side correlation is gone!back-to-back jets are quenched
At lower pT: away-side correlations returnbut they are highly modified with a double
bump!?We will try to understand what causes this behavior
pT,trig>4 GeV/c pT,ass>2 GeV/c
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0.6
0.4
0.0
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
pT,trig>2.5 GeV/c pT,ass>1.0 GeV/c
STAR preliminary
4STARSTAR
Centrality dependence
Singly-peaked -> broadened -> becomes doubly bump
What’s the baryon/meson ratio in the near- and away-side peak?
What are the anti-baryon-to-baryon ratios?
We will measure the ratios to try to understand the source of the correlations in different centralities.
pT,trig>2.5 GeV/c pT,ass>1.0 GeV/cM. Horner, QM06
5STARSTAR
STAR preliminary
B/M Ratio Intermediate pT
large enhancement of baryon/meson ratio in central Au+Au relative to p+preaches maximum at pT~3 GeV/c
Perhaps related to faster increase with centrality of baryon production from recombination
Intermediate pT, Baryon & Meson:Grouping of RCP and v2
----recombination pictures
Can recombination explain particle ratios in the jet cones?
6STARSTAR
Anti-B/B Ratio Intermediate pT
We can also learn about gluons vs quarks from B/B ratios with the jet correlation.
For example: anti-baryons dominated by gluon jetsbaryons mixture of quark and gluon
STAR preliminary
7STARSTAR
Anti-Baryon Density
• Collisions which contain ggg, qbar+g or qqbar+g processes have higher anti-baryon phase space density• Anti-baryon phase space density from collisions involving a gluon is much higher than those without a gluon
STAR preliminaryH.D.Liu QM06
From B/B ratios in the correlation• Baryon & Anti-baryon production with Jets• Gluon vs. Quarks with Jets
H. Liu, Z. Xu nucl-ex/0610035
ppTmpd B //exp/
8STARSTAR
Trigger-associate correlations
Identified particles correlations & B/M , B/B ratio
can provide additional information on:• jet quenching • baryon/meson enhancement at
STAR• particle production
mechanisms • Di-hadron correlation Away-side
shape
We’ll study identified associate particles using
•Trigger: Charged hadron, pT>3.0 GeV/c
•Associate: KS0, , or (i.e. V0 decay), pT>1.0 GeV/c
parton
trigger hadron
Λ, Λ, K0S
Λ, Λ, K0S
parton
near-side associated
away-side associated
9STARSTAR
Analysis method
Step 1: 3-D histogram with , , and minv (Trigger-V0 pair)
Step 2: Project over a given rangein this talk I show results for -1<<1: (combine jets & some ridge)
Step 3: Plot minv vs. Fit the minv distribution yield dN/d ( KS
0, , or )
minv
minvStep 4: Repeat 1 to 3 with mixed eventsStep 5: Scale the mixed event background with measured v2
Subtract off the background • ZYAM (zero-yield at the minimum) • ZYA1 (zero-yield at one )
10STARSTAR
Hadron_Ks & + Correlation
• Centrality Dependence– Double bump -> Broadened -> Singly-peaked– The shape consistent with di-hadron correlation
peripheral
3<pT,trig<6 GeV/c; 1<pT,ass<4 GeV/c
central
11STARSTAR
Hadron_Ks & + Correlation
• Centrality bin: 10-40%
• The yellow band : systematic error
• From the line: Left part: near-side Right part: away-side
Particle Ratios Near-Side Away-Side
(+)/Ks0.77 0.12 (stat) 0.18
(sys)1.7 0.3 (stat) 0.6
(sys)
Near-Side Away-Side
3<pT,trig<6 GeV/c 1<pT,ass<4 GeV/c
12STARSTAR
STAR Preliminary
Baryon to Meson Ratio with Jets
• Lambda to Ks Ratio : Away-Side > Near-Side• Anti-Proton to Ratio : Away-Side > Near-Side (PHENIX)
Both STAR and PHENIX results consistent with larger B/M ratio on the Away-Side than Near-Side.
13STARSTAR
The shape of the ratio
away
near
Medium
mach cone
Mediumaway
near
deflected jets
Can we learn something about the shape on the away-side?• Sound wave excitation particles maybe slower than the speed of sound (vs=c/3)
• For our pT range slower particles would have to be heavy
For production from sound wave excitation the bumps should have mostly heavy particles (+)/KS
0 would get large in the bump region
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.0.2
0.6
0.4
0.0
pT,trig>2.5 GeV/c pT,ass>1.0 GeV/c
STAR preliminary
• Mach Cone Concept/Calculations
Stoecker, Casalderry-Solana et al; Muller et al.; Ruppert et al., …
• Cherenkov RadiationMajumder, Koch, & Wang; Vitev
• Jet Deflection (Flow) Fries; Armesto et al.; Hwa
M. Horner, QM06
14STARSTAR
B/M Ratio in Distribution
???
away
nearM
edium
mach cone
Δ= Trigger
Δ = /2
Medium
Ass
ocia
te
• A slope at Away-Side? A slope at Away-Side? Slow particle Double bump Slow particle Double bump KKSS
00 Fast particle Double bump ?? Fast particle Double bump ??• B/M ratio: Away-Side seems to increase in the "cone" region - as it maybe for B/M ratio: Away-Side seems to increase in the "cone" region - as it maybe for
sound wave excitation. sound wave excitation.
• Increased B/M ratio may also be consistent with recombination in high density Increased B/M ratio may also be consistent with recombination in high density region of the shock-waveregion of the shock-wave
• Error bars too large to get strong conclusionsError bars too large to get strong conclusions • The same shape in the away-side using v2 background from three different methods
• The shape of Baryon to Meson ratio on the away-side seems to be independent of v2 background and background subtraction method.
• Perhaps a slope , but error bars are still too large to draw conclusions.
+KS0
15STARSTAR
• (B/M)A to (B/M)N double ratio from central to peripheral– 00-10% &10-40%
• Maybe a slope here
– 40-80% • Difficult to describe
• In the correlation function,– 00-10% &10-40%
• There is a double bump and broadened away-side.
– 40-80% • There seems to be a single peak.
(B/M)A to (B/M)N double ratio
pe
riph
era
lc
entra
l
16STARSTAR
• Centrality Dependence– Double bump, Broadened & Singly-peaked– The shape consistent with di-hadron correlation
Hadron_ & Correlation
peripheral
3<pT,trig<6 GeV/c; 1<pT,ass<4 GeV/c
central
17STARSTAR
Hadron_ & Correlation
Centrality bin: 10-40%
• The yellow band: Systematic error.
• From the line: Left part: near-side Right part: away-side
Particle Ratios
Near-Side Away-Side pT=1.5GeV/c
/ 0.92 0.20 (stat) 0.20 (sys)
0.89 0.17 (stat) 0.37 (sys)
0.76 0.013
Near-Side Away-Side
3<pT,trig<6 GeV/c 1<pT,ass<4 GeV/c
18STARSTAR
• (B/B)A to (B/B)N ratio from central to peripheral
• The ratio is around one• Maybe a slope at here,
but error bars are still too large to conclude.
Why is it a slope?? • Independent of v2 and
background subtraction method
(B/B)A to (B/B)N ratio
pe
riph
era
lc
entra
l
19STARSTAR
Summary• Measured the Conditional Yields of identified associate particles on the
near- and away-side of jets• From central to peripheral : Double bump -> Broadened -> Singly-peaked• Extracted particle ratios on the near and away-side• Systematic errors from v2 and background normalization are large
– errors can be reduced with more data (to reduce error on the level of the background)
– and better understanding of v2 (to reduce uncertainty on the shape of the background)
• Both STAR and PHENIX results consistent with larger B/M ratio on the away-side than near-side
• Shape of away-side has been studied– some indication of a slope for B/M and / on the away-side (mach-cone?
gluon vs. quark? Or others?)– slope of B/M and / on the away-side seems to be independent of v2 and
background subtraction method
Thanks!!Thanks!!Acknowledgments: STAR Collaboration Acknowledgments: STAR Collaboration Dr. Paul Sorensen Dr. Paul Sorensen
20STARSTAR
The Collaboration
Shanghai Institue of Applied Physics - Argonne National Laboratory Institute of High Energy Physics - University of Birmingham - Brookhaven National Laboratory - California Institute of Technology - University of California, Berkeley - University of California, Davis - University of
California, Los Angeles - University of Illinois at Chicago - Carnegie Mellon University - Creighton University – Nuclear Physics Inst., Academy of Sciences - Laboratory of High Energy
Physics - Particle Physics Laboratory - University of Frankfurt - Institute of Physics, Bhubaneswar - Indian Institute of Technology, Mumbai - Indiana University Cyclotron Facility -
Institut de Recherches Subatomiques de Strasbourg - University of Jammu - Kent State University - Institute of Modern Physics - Lawrence Berkeley National Laboratory -
Massachusetts Institute of Technology - Max-Planck-Institut fuer Physics - Michigan State University - Moscow Engineering Physics Institute - City College of New York - NIKHEF and
Utrecht University - Ohio State University - Panjab University - Pennsylvania State University - Institute of High Energy Physics - Purdue University – Pusan National University - University of Rajasthan - Rice University - Instituto de Fisica da Universidade de Sao Paulo - University of
Science and Technology of China - SUBATECH - Texas A&M University - University of Texas, Austin - Tsinghua University - Valparaiso University – Variable Energy Cyclotron Centre,
Kolkata - Warsaw University of Technology - University of Washington - Wayne State University - Institute of Particle Physics - Yale University - University of Zagreb -UNICAMP
21STARSTAR
Backup
22STARSTAR
V0 reconstructionV0s from UCLA/LBL picoDsts
23STARSTAR
a.u.
pTtrig=3-6 GeV/c,
1.5 GeV/c <pTassoc< pT
trig
Au+Au central @ 200 GeV
ridge
ridge
jet
jet+ridge after v2 subtraction
jetridge
v2 + away-side peak
h-h
Au+Au: long-range correlations at near side (“the ridge”)
Lesson: The near-side jet does interact with the medium
Fragmentation and energy loss - near-side
Di-hadron correlations
trigger
24STARSTAR
Ks, & Hadron v2 • Background: V0 & Hadron v2
• Background function: B()=b0(1+2<v2
A*v2B>cos(2))
• Final results background: Average v2 – Ks and v2{EP} & v2{LYZ}– Charged Hadron: v2{EP} & v2{4}
• A part of systematic errors will be calculated by the v2{EP} & v2{LYZ}, v2{4}
Weight average flow:
v2 Hadron Ks Lambda
00-100.0811912+-0.00736462
0.04393416+-0.000463404
0.0459624+-0.000490826
10-400.151251+-0.00175313
0.104353+-0.000916851
0.105984+-0.00108642
40-800.235884+-
0.0013962480.1222672+-0.000545339
0.144212+-0.000647908
• V0 LYZ v2: pt [1,4]• Hadron v2{4}: pt [3.2,6.5]
v2{4} & v2{EP} Phys. Rev. C 72 (2005) 014904 v2{LYZ} paper in preparation
25STARSTAR
• Lee-Yang Zeroes method is less biased by non-flow correlation.
Nucl. Phy. A 727 (2003) 373-426
• Sum generating function:– Flow vector projection into arbitrary angel .
– Generating function for a given .
• Integrated flow: – From the first minimum r0
• Differential flow
Lee-Yang Zeroes method
First minimum of |G|2 determines r0
all events
average over
all particles in all events
average over removes acceptance effects
26STARSTAR
Same Event & v2 BackgroundS
TA
R p
relim
inar
y
for these plots, efficiency correction not applied
27STARSTAR
Ratio vs.
• B/M Ratio at Near-Side
• B/M Ratio vs. at Away-Side
B/B Ratio at Near-Side
B/B Ratio vs. at Away-Side