STAR 1 Strange Particle Ratios on the Near- & Away-Side of Jets at RHIC Jiaxu Zuo BNL/SINAP with Paul Sorensen BNL For STAR Collaboration 23rd Winter Workshop.
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Presentation on theme: "STAR 1 Strange Particle Ratios on the Near- & Away-Side of Jets at RHIC Jiaxu Zuo BNL/SINAP with Paul Sorensen BNL For STAR Collaboration 23rd Winter Workshop."— Presentation transcript:
STAR 1 Strange Particle Ratios on the Near- & Away-Side of Jets at RHIC Jiaxu Zuo BNL/SINAP with Paul Sorensen BNL For STAR Collaboration 23rd Winter Workshop on Nuclear Dynamics
STAR 2 Outline Motivation Analysis Method Results & Discussions Summary STAR Au+Au 200GeV run4 Data 13M Events Related STAR analysis presented at WWND07: Near-side correlations of strange baryons and mesons (Jana Bielcikova) Mulit-strange triggers correlations (Betty Abelev)
STAR 3 Di-hadron correlations For high p T :away-side correlation is gone! back-to-back jets are quenched At lower p T :away-side correlations return but they are highly modified with a double bump!? We will try to understand what causes this behavior p T,trig >4 GeV/c p T,ass >2 GeV/c 0.2 0.6 0.4 0.0 p T,trig >2.5 GeV/c p T,ass >1.0 GeV/c STAR preliminary
STAR 4 Di-hadron correlations 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 0.2 0.6 0.4 0.0 p T,trig >2.5 GeV/c p T,ass >1.0 GeV/c STAR preliminary
STAR 5 Intermediate p T particle ratios large enhancement of baryon/meson ratio in central Au+Au relative to p+p reaches maximum at p T ~3 GeV/c Perhaps related to faster increase with centrality of baryon production from recombination
STAR 6 Intermediate p T particle recombination pictures of intermediate p T particle production: supported by meson and baryon grouping of R CP and v 2 can recombination explain particle ratios in the jet cones?
STAR 7 Intermediate p T particle ratios We can also learn about gluons vs quarks from B/B ratios for example:anti-baryons dominated by gluon jets baryons mixture of quark and gluon STAR preliminary
STAR 8 Trigger-associate correlations identified correlations at high-p T can provide additional information on: jet quenching baryon/meson enhancement at STAR particle production mechanisms Λ from q-jet and g-jet, Λ more from g-jet We’ll study identified associate particles using Trigger: High p T charged hadron p T >3.0 GeV/c Associate: K S, , or (i.e. V 0 decay) with p T >1.0 GeV/c parton trigger hadron Λ, Λ, K 0 S parton near-side associated away-side associated
STAR 9 Analysis method Step 1:for each trigger-V 0 pair fill a 3-D histogram with , , and m inv Step 2:I project over a given range in this talk I show results for -1< <1: this combine jets & some ridge Step 3:plot m inv vs fit the m inv distribution to get the yield dN/d for K S, , or m inv Step 4:repeat 1 to 3 with mixed events Step 5:scale the mixed event background with measured v 2 subtract off the background assuming zero-yield at the minimum or zero-yield at one (ZYAM or ZYA1) Jana Bielcikova's talk
STAR 10 Ks & Lambda Mass Fit Ks and Lambda Invariant Mass distribution in different bins 10-40%
STAR 11 Same Event & v 2 Background STAR preliminary for these plots, efficiency correction not applied
STAR 12 Hadron_Ks & + Correlation distribution of Hadron_Ks & + Correlation 10-40% Near-Side: Ks seems higher than Lambda+Anti-Lambda, point by point. Away-Side: It seems that Ks is lower than Lambda+Anti- Lambda. Particle Ratios Near-SideAway-Side ( + )/Ks 0.765(0.120(Stat.) 0.175(Sys.)) 1.71(0.321(Stat.), 0.589(Sys.)) Near-SideAway-Side 3<p T,trig <6 GeV/c 1<p T,ass <4 GeV/c efficiency corrections now applied
STAR 13 Baryon to Meson Ratio with Jets pbar to Ratio : Away-Side > Near-Side (PHENIX) Lambda to Ks Ratio : Away-Side > Near-Side
STAR 14 (B/M) Away /(B/M) Near Double Ratio at PHENIX & STAR Both STAR and PHENIX data are consistent with a larger B/M ratio on the away-side -> more matter seems to yield more baryons (B/M) Away /(B/M) Near Double Ratio 1<p T,assoc <4, 3<p T,trig <6 PHENIX: Meson Trigger PHENIX QM05 Nucl-ex/0510040
STAR 15 The shape of the ratio away near Medium mach cone Medium away near deflected jets can we learn something about the shape on the away-side? mach cone particles must be slower than the speed of sound for our p T range they would have to be heavy for mach-cone emission the bumps should have mostly heavy particles ( + )/K S would get large in the bump region 0.2 0.6 0.4 0.0 p T,trig >2.5 GeV/c p T,ass >1.0 GeV/c STAR preliminary
STAR 16 B/M Ratio in Distribution Slow particle Mach ConeA slope at Away-Side? Slow particle Mach Cone Ks Fast particle Mach Cone?? Ks Fast particle Mach Cone?? B/M ratio: Away-Side seems to increase in the "cone" region - as it should for mach cone emissionB/M ratio: Away-Side seems to increase in the "cone" region - as it should for mach cone emission Error bars are still too large to concludeError bars are still too large to conclude ??? away near Medium mach cone Δ=Δ= Trigger Δ = /2 Medium Associate
STAR 17 Hadron_ & Correlation distribution of Hadron_ & Correlation 10-40% Near-Side: Anti-Lambda and Lambda seems consistent. Away-Side: Seems a little difference between Anti-Lambda and Lambda from correlation function Particle Ratios Near-SideAway-Side // 0.916(0.200(Stat.), 0.200(Sys.)) 0.894(0.173(Stat.), 0.368(Sys.)) Near-SideAway-Side 3<p T,trig <6 GeV/c 1<p T,ass <4 GeV/c
STAR 18 The Ratio at Near-Side & Away-Side is consistent with non-trigger Anti-B/B ratio. STAR preliminary Anti-B/B Ratio in Distribution
STAR 19 Anti-B/B Ratio in Distribution Anti-B/B Ratio : The same slope at Away-Side?? Why is it a slope?? If it is, Why is it a slope??
STAR 20 Summary Measured the Conditional Yields of identified associate particles on the near- and away-side of jets Extracted particle ratios on the near and away-side Systematic errors from v 2 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 v 2 (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?) –slope of B/M and / on the away-side seems to be independent of v 2 and background subtraction method