Interplay between soft and hard hadronic components at RHIC Tetsufumi Hirano RIKEN BNL Research Center OUTLINE Introduction Hydro+jet model Back-to-back correlations of high p T hadrons Transverse dynamics of identified hadrons SummaryOUTLINE Introduction Hydro+jet model Back-to-back correlations of high p T hadrons Transverse dynamics of identified hadrons SummaryReferences T.H. and Y.Nara, Phys.Rev. C66, (2002); Phys.Rev.Lett. 91, 82301(2003); nucl-th/ ; nucl-th/ References T.H. and Y.Nara, Phys.Rev. C66, (2002); Phys.Rev.Lett. 91, 82301(2003); nucl-th/ ; nucl-th/ RCNP, Oct.28, 2003 Collaboration with Yasushi Nara (Arizona)

Subjects I will NOT cover today! T.Hirano (’02) T.Hirano and K.Tsuda (’02) T.Hirano and Y.Nara, in progress T.Hirano and K.Tsuda (’02) T.Hirano and Y.Nara, in progress

QGP? Introduction 1. Jet quenching 2. Jet acoplanarity (transverse momentum imbalance) correlate ? Gyulassy, Plumer (’90) Wang, Gyulassy (’92) and a lot of work Bjorken (’82) Appel (’86) Blaizot, McLerran (’86) Rammerstorfer, Heinz (’90) g g g Hot and dense matter produced in heavy ion collisions Not static, but dynamic! Need a dynamic model Hot and dense matter produced in heavy ion collisions Not static, but dynamic! Need a dynamic model Au 100A GeV

High p T data at RHIC From D. d’Enterria(PHENIX), talk at QM2002. See also, S.S.Adler et al.(PHENIX), PRL91,072301(2003). From D.Hardtke (STAR), talk at QM2002. See also, C.Adler et al. (STAR), PRL90,082302(2003). ???

# of binary collisions x y Thickness function: Woods-Saxon nuclear density: Gold nucleus:  0 =0.17 fm -3 R=1.12A 1/ A -1/3 d=0.54 fm  in = N coll & N part # of participants 1 －（ survival probability ）

pTpT R AA 1 binary collision scaling Au+Au 0-10% central b=2.8 fm N coll = 978 N part = 333 N part /N coll = participant scaling Nuclear Modification Factor (null result)

Before d+Au Results… D.Kharzeev et al., hep-ph/

Initial or Final ? D.Kharzeev et al., Phys.Lett.B561, 93(2003). Parton saturation  N part scaling gg  g (no b-to-b) I.Vitev and M.Gyulassy, Phys.Rev.Lett. 89, (2002) pQCD+Cronin+shadowing +jet quenching+simple expansion

Recent Data in d+Au Collisions Something happens only in AuAu collisions? Jet quenching scenario is favored and initial state effect is ruled out. But, this does not mean saturation models are killed. PRL91,(03)072302; ; ;

Hydro + Jet Model

Model Jet quenching Jet acoplanarity Interaction between soft and hard is important! Soft (hydrodynamics) Space-time evolution of matter Phase transition between QGP and hadrons Particle spectra in low p T region Hard (mini-jets) Production of (mini-)jets Propagation through fluid elements Fragmentation into hadrons Interaction between fluids and mini-jets through parton energy loss

Brief Summary of Our Hydro Results Full 3D hydro!   No Bjorken scaling ansatz   No cylindrical symmetry   ( ,  s, x, y) coordinate T.Hirano, Phys.Rev.C65(2002) T.Hirano and K.Tsuda, Phys.Rev.C66(2002)   Suppression of radial flow, elliptic flow and HBT radii in comparison with the conventional hydro results.

Need hard components? Limit of High p T p T slope for pions becomes insensitive to T th in considering early chemical freezeout. PHENIX  Also one of the strong motivations of constructing the hydro+jet model

PYTHIA(+Hydro) N N 3 4 Fragmentation: Independent Fragmentation Model PYTHIA 3D Hydro PYTHIA hadrons PDF: Collinear: CTEQ5LO k T : Gaussian Parton energy loss pQCD LO: *Initial and final state radiation are included.

Results from PYTHIA PHENIX  0 in pp hep-ex/ UA1 charged in pp Nucl.Phys.B335, 261(1990).

Free streaming Hydro evolution Time Evolution in Hydro+Jet Model  00 Energy loss Fragmentation ff =0.6fm/c~10fm/c0 Formation time~0 fm For jets with p T >2GeV/ c, 1/ p T <0.1fm/ c <<1fm/ c Momentum dist. from PYTHIA ver. 6.2 Thermalization time = Initial time of fluids Initial parameters in hydro have been already tuned. After hydro simulation, all survival jets fragment into hadrons. We neglect interaction of fragmented hadrons. Jets Full 3D hydro Particle spectra through Cooper- Frye formula CGC? Prethermaliztion?

Jets and Hydro Evolution in the Transverse Plane Initial configuration of mini-jets   Prop. to # of binary collisions Assuming jets move along straight paths (eikonal approximation) Au+Au 200AGeV, b=8 fm transverse Gradation  Themalized parton density Plot (open circles)  Mini-jets (p T >2GeV/c)  (fm -3 ) x(fm) y (fm)

Suppression Factor for  0 GLV formula with C=0.27 quantitatively reproduces the data Data from S.S.Adler et al. (PHENIX), PRL91,072301(2003). Our starting point of the following discussion b=2.8fm Simplified GLV 1 st order formula: M.Gyulassy et al., NPB594, 371 (2000).

Parton Energy Loss Position of a jet Adjustable parameter Parton density from hydrodynamic simulations  We have already had a solution! Initial 4-momentum of a jet in local rest frame M.Gyulassy et al. (2000) Simplified GLV formula 1st order in opacity expansion Relevant for heavy-ion collisions

Suppression Factor for  0 The coherent model with C=0.27 quantitatively reproduces the data Data from S.S.Adler et al. (PHENIX), nucl-ex/ Our start point of the following discussion b=2.8fm

Back-to-Back Correlations of high p T hadrons

Associated particles Trigger particles Azimuthal Correlation Function p+p A+A  p T (GeV/c) STAR Strength of away-side peaks are the same in no jet quenching case Back-to-back correlations of high p T hadrons

Back-to-Back Correlations of High p T hadrons From D.Hardtke (STAR), talk at QM2002. See also, C.Adler et al.(STAR), PRL90,082302(2003). Central collisionsPeripheral collisions Disappearance of away-side peaks! ???

Three Possible Effects on Back- to-back Correlations 1.Energy loss of jets 2. Primordial k T of initial partons 3. Broadening of jets Final stateInitial stateFinal state Absorption “Cronin effect” Random walk behavior Nucleon inside a nucleus Target nucleus Beam direction Hot matter

Disappearance of B-to-B energy loss +Cronin effect +broadening Energy loss is dominant, but insufficient. Nucleon inside a nucleus Target nucleus Beam direction Hot matter

Three Possible Effects on Back- to-back Correlations 1.Energy loss of jets 2. Primordial k T of initial partons 3. Broadening of jets Final stateInitial stateFinal state Absorption “Cronin effect” Random walk behavior Nucleon inside a nucleus Target nucleus Beam direction Hot matter

1. Effect of Parton Energy Loss Hot matter Simultaneous reproduction of R AA and C 2 ?  Another mechanism is needed! C=0.27  From fitting R AA

Three Possible Effects on Back- to-back Correlations 1.Energy loss of jets 2. Primordial k T of initial partons 3. Broadening of jets Final stateInitial stateFinal state Absorption “Cronin effect” Random walk behavior Nucleon inside a nucleus Target nucleus Beam direction Hot matter

Intrinsic k T is insufficient to the disappearance of back-to-back correlation! Intrinsic k T is insufficient to the disappearance of back-to-back correlation! Primordial k T distribution 2. Effect of Intrinsic k T collinearintrinsic k T Nucleon inside a nucleus Target nucleus Beam direction

Three Possible Effects on Back- to-back Correlations 1.Energy loss of jets 2. Primordial k T of initial partons 3. Broadening of jets Final stateInitial stateFinal state Absorption “Cronin effect” Random walk behavior Nucleon inside a nucleus Target nucleus Beam direction Hot matter

3. Effect of Broadening Transverse momentum orthogonal to its direction of motion Hot matter Model 1 (BDMPS): Model 2 (XNW):

Surface Emission Dominance ? Initial positions of jets which survive at final time Completely Partially No quenchingC=0.25 C=1.0 An interesting signature may be events in which the hard collision occurs near the edge of the overlap region, with one jet escaping without absorption and the other fully absorbed. --J.D.Bjorken, FERMILAB-Pub-82/59-THY (1982).

Transverse Dynamics of Identified Hadrons

Are protons and anti-protons suppressed ?  protons    h J.Velkovska, talk at DNP

Article from SCIENCE ! C.Seife, Science298, 718(2002)

Hydro and Hydrojet P T spectrum becomes convex to concave. Inflection points at ~ 2.8 GeV/c (kaons) ~ 3.5 GeV/c (protons) Radial flow pushes heavier particles to high p T.

p T Spectra for Identified Hadrons p T,cross depends on particle species! particle species!

Interplay between Radial Flow and Jet Quenching pTpTpTpT (1/p T )(dN/dp T ) Hydrodynamicafterburner Quenching Two components picture  Intermediate region might be complicated.  Really need coalescence picture???

R AA and Ratio for Identified Hadrons Not absence of jet quenching, just radial flow

v 2 (p T ) for Identified Hadron PHENIX, nucl-ex/ v 2,p >v 2,  hardly obtained by using hydrodynamics.

v 2 (p T ) for Identified Hadrons(cond.) Hydro results: Low p T  Defference comes from mass High p T  All v 2 ’s merge (p T >>m) Interchanging behavior of v 2 for id. hadrons  Comes from hadron species dependence of p T,cross v 2,K <v 2,  ???

Hydro+Jet or Coalescence? R.J.Fries et al., nucl-th/ Recombination + Fragmentation Hydro+Jet p T /n < 1 GeV/c

Jet Quenching at Off-Midrapidity BRAHMS, PRL91,072305(2003)

Hydro+Jet at Off-Midrapidity charged Dynamical effects should be identical between  =0 and 2. Steeper pQCD component in forward rapidity.

Hydro+Jet at Off-Midrapidity (cond.) R AA might be, in a sense, not a good quantitative Indicator of jet quenching. Anyway, R h <1 can be manifestation of dense matter in forward rapidity region R AA might be, in a sense, not a good quantitative Indicator of jet quenching. Anyway, R h <1 can be manifestation of dense matter in forward rapidity region Jet quenching  Shift of a spectrum Modification factor  Ratio at some p T

Why R AA (  =0)>R AA (  ~2)? Jet quenching is a shift of spectrum. pTpT (1/p T )dN/dp T “parallel shift” pTpT (1/p T )dN/dp T Different slope, but same shift 0 0 R AA is a ratio at a p T.

v 2 in forward rapidity region Charged pQCD only b=7.2fm 20-30% Disentangle matter effect from “slope” effect “slope” effect x y

Summary We construct a dynamical model in which hydrodynamics is combined with explicit traversing non-thermalized partons. Back-to-back correlations  Three effects (energy loss, intrinsic k T, broadening) are found to be responsible for disappearance of away-side peak. (dominant effect  energy loss) Neither “SOFT PHYSICS” nor “HARD PHYSICS”. Interplay between soft (radial flow) and hard (jet quenching) is important in understanding existing data.   Species dependence p T,cross : (  ) < (K) < (proton)   (R AA for protons) > 1 in 1.5<p T <2.5 GeV/c   (p/  ) ~ 1 in 2<p T <3 GeV/c   Crossing v 2 for identified hadrons   Jet quenching (v 2 ) in forward rapidity region Intermediate p T is interesting!

Thank you! Movie is now available at Data of thermalized parton density are now available at Presentation files are now available at