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Near-side correlations of high-p t hadrons from STAR Jörn Putschke for the STAR collaboration Lawrence Berkeley National Laboratory Weisshorn (4505m), Switzerland
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Jörn Putschke, Quark Matter 2006, Shanghai2 “Ridge” observation Additional near-side long range corrl. in (“ridge like” corrl.) observed. Dan Magestro, Hard Probes 2004, STAR, nucl-ex/0509030, Phys. Rev. C73 (2006) 064907 and P. Jacobs, nucl- ex/0503022 Phys. Rev. C73 (2006) 064907 p t < 2 GeV d+Au, 40-100% Au+Au, 0-5% 3 < p T (trig) < 6 GeV 2 < p T (assoc) < p T (trig)
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Jörn Putschke, Quark Matter 2006, Shanghai3 3<p t,trigger <4 GeV p t,assoc. >2 GeV Au+Au 0-10% STAR preliminary Outline 2-particle correlations: How to extract the “ridge” yield ? (additional near-side long range corrl. in ) Quantify ridge properties in Au+Au (Cu+Cu) 200 GeV collisions Summary & discussion
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Jörn Putschke, Quark Matter 2006, Shanghai4 Scenarios i) Parton radiates energy before fragmenting and couples to the longitudinal flow — Gluon bremsstrahlung of hard-scattered parton — Parton shifted to lower p t — Radiated gluon contributes to broadening near-side jet also looses energy (finite pathlength)! ii) Medium heating + Parton recombination (Chiu & Hwa Phys. Rev. C72:034903,2005) — Recombination of thermal partons only indirectly affected by hard scattering not part of the jet iii) Radial flow + trigger bias (Voloshin nucl-th/0312065, S. A. Voloshin, Nucl. Phys. A749, 287 (2005)) Armesto et al, PRL 93 (2004), nucl-ex/0405301
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Jörn Putschke, Quark Matter 2006, Shanghai5 Components of correlations Au+Au 20-30% a b cc b a)Near-side jet-like corrl. + ridge-like corrl. + v 2 modulated bkg. b)Ridge-like corrl. + v 2 modulated bkg. c)Away-side corrl. + v 2 modulated bkg. Strategy: Subtract from projection to isolate the ridge-like correlation Au+Au 0-10% STAR preliminary
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Jörn Putschke, Quark Matter 2006, Shanghai6 (J+R) | |<1.7 J = near-side jet-like corrl. R = “ridge”-like corrl. v 2 modulated bkg. subtracted (J+R) | |<1.7 flow (v 2 ) corrected Extracting near-side “jet-like” yields 1 Au+Au 20-30% 2 2 (J+R) - (R) const bkg. subtracted (J) | |<0.7 (J) no bkg. subtraction const bkg. subtracted (J) | |<0.7
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Jörn Putschke, Quark Matter 2006, Shanghai7 Extracting the ridge yield Definition of “ridge yield”: i) ridge yield := Jet+Ridge( Jet( ) ii) relative ridge yield := ridge yield / Jet( ) STAR preliminary Jet+Ridge ( ) Jet ( ) Jet ) yield , ) N part 3 2 GeV Jet yield independent of N part and consistent with d+Au reference measurements !
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Jörn Putschke, Quark Matter 2006, Shanghai8 Ridge shape measurement in central Au+Au I STAR preliminary 3 2 GeV STAR preliminary yield ) yield ) 3 2 GeV STAR preliminary
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Jörn Putschke, Quark Matter 2006, Shanghai9 Ridge shape measurement in central Au+Au II Ridge yield as function of saturates at high non-uniform ridge shape in Au+Au 0-10% STAR preliminary p t,assoc. > 2 GeV ridge yield
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Jörn Putschke, Quark Matter 2006, Shanghai10 Ridge yield in Au+Au p t,assoc. > 2 GeV STAR preliminary Ridge yield persists to highest trigger p t correlated to jet production
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Jörn Putschke, Quark Matter 2006, Shanghai11 “Jet yield” vs. p t,assoc. in central Au+Au “Jet spectrum” much harder than inclusive h and increasing with p t,trigger STAR preliminary Jet yield inclusive Jet yield (p t,assoc > p t,assoc,cut ) p t,assoc,cut
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Jörn Putschke, Quark Matter 2006, Shanghai12 Ridge yield vs. p t,assoc. in central Au+Au STAR preliminary “Ridge spectrum” slightly harder than inclusive h and ~ independent of p t,trigger inclusive Ridge yield (p t,assoc > p t,assoc,cut ) p t,assoc,cut
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Jörn Putschke, Quark Matter 2006, Shanghai13 “Jet”/ridge yield vs. p t,assoc. in central Au+Au preliminary Au+Au 0-10% preliminary Ridge / Jet yield STAR preliminary Ridge Jet p t,assoc,cut Ridge/Jet yield (p t,assoc > p t,assoc,cut ) STAR preliminary “jet” slope ridge slope inclusive slope
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Jörn Putschke, Quark Matter 2006, Shanghai14 “Jet”/Ridge energy STAR, Phys. Rev. Lett. 95 (2005) 15230 0.15 < p t,assoc < 4 GeV 4 < p t,trigger < 6 GeV 6 < p t,trigger < 10 GeV Applying this “2-component picture” to lower p t,assoc measurements (see M. Horner’s talk: z t,jet (Au+Au) ~ z t,jet (d+Au) subtracting p+p jet energy from Au+Au) upper estimate of the energy deposit in the ridge ~ few GeV Consistent with energy loss picture ? “Ridge energy” “Ridge energy” } }
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Jörn Putschke, Quark Matter 2006, Shanghai15 Ridge yield in Au+Au and Cu+Cu Relative ridge yield comparable at same N part in Au+Au and Cu+Cu p t,assoc. > 2 GeV STAR preliminary relative ridge yield relative ridge yield := ridge yield / Jet( ) Au+Au 200 GeV Cu+Cu 200 GeV 3<p t,trigger <4 GeV Au+Au 200 GeV (30-40 %) Cu+Cu 200 GeV (0-10 %)
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Jörn Putschke, Quark Matter 2006, Shanghai16 Ridge characteristics STAR Au+Au 0-10%, RHIC, US (~0m) preliminary Weisshorn (4505m), Switzerland ridge persists up to highest trigger p t correlated to jet production (~ independent on trigger p t ) ridge spectrum ~ “bulk-like” ridge energy roughly a few GeV ridge comparable in Au+Au and Cu+Cu at same N part non-uniformity of ridge shape in observed; needs further investigation (only small effect expected)
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Jörn Putschke, Quark Matter 2006, Shanghai17 Discussion p t,assoc. ridge/jet yield h +,- ridge jet increasing p t,trig ridge spectrum slightly harder (?) than inclusive h +,- (tens of MeV) consistent with medium heating parton recombination ( T~15 MeV) ? agreement with radial flow + jet quenching ? ridge spectrum qualitatively in agreement with parton energy loss and coupling to longitudinal flow quantitative calculation for comparison needed
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Jörn Putschke, Quark Matter 2006, Shanghai18 Outlook Study geometry effects in more detail: Look at near-side modifications in Au+Au with respect to the reaction plane PID ridge yield study with , protons and strange particles (see J. Bielcikova’s talk) Systematic studies of the ridge shape at higher trigger p t and 3-particle near-side correlations Part / Col Au+Au 30-40% Part / Col Cu+Cu 0-10% Part ~ energy density Coll ~ parton origin x [fm] y [fm] STAR very preliminary ! 12 13
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Jörn Putschke, Quark Matter 2006, Shanghai19 Backup slides
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Jörn Putschke, Quark Matter 2006, Shanghai20 Analysis methods cont. preliminary v 2 subtraction and systematic error estimation Au+Au: a)Used v 2 values = mean between v 2 RP and v 2 {4} measurements b)Systematic errors mainly due to uncertainties in v2; use v 2 RP and v 2 {4} as upper and lower limit v 2 subtraction and systematic error estimation Cu+Cu: a)Used v 2 values = v2{CuCu-pp} b)Systematic errors mainly due to uncertainties in v2; use v 2 RP and no flow as upper and lower limit QM05 1.Use event-mixing to account for pair acceptance & use eff. correction for ass. particles 2.Background: a)Subtract constant background for (J) method b)Subtract v 2 modulated background for (J+R) method 3.Assume Gaussian correlation shape: yield( ) = gaus integral / bin counting ( ) = gaus width
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Jörn Putschke, Quark Matter 2006, Shanghai21 p t,assoc. > 2 GeV STAR preliminary Jet+Ridge yield ( ) Jet yield ( ) Jet and Jet+Ridge yields & widths Jet+Ridge yield increasing with centrality Jet+Ridge shape asymmetric in and preliminary p t,assoc. > 2 GeV Jet+Ridge width ( ) central Correlate Jet ( (J)) and Jet+Ridge ( (J+R)) widths & yields via centrality Jet width ( ) STAR preliminary central periph. YieldWidth
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Jörn Putschke, Quark Matter 2006, Shanghai22 Jet yields & widths: vs. Correlate Jet ( (J)) and Jet ( (J)) widths and yields via centrality p t,assoc. > 2 GeV Jet yield ~ symmetric in Jet shape ~ symmetric in for p t,trig > 4 GeV (asymmetric in for p t,trig < 4 GeV) STAR preliminary centralperiph. Jet yield ( ) Jet yield ( ) Jet width ( ) Jet width ( ) Yield Width
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Jörn Putschke, Quark Matter 2006, Shanghai23 “Jet”/Ridge energy/multiplicity STAR, Phys. Rev. Lett. 95 (2005) 15230 “Ridge N ch ” “Ridge energy” “Ridge energy” 0.15 < p t,assoc < 4 GeV
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Jörn Putschke, Quark Matter 2006, Shanghai24 Pion vs. Proton relative ridge yield STAR preliminary p t,assoc. > 2 GeV Au+Au 0-10% Proton content of ridge larger than of jet part (more from strange assoc. particles in J. Bielcikova’s talk) Assoc. Protons Assoc. Pions Assoc. h
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