Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

Roy_Lacey

VIEWS: 8 PAGES: 29

									                   Roy A. Lacey, Stony Brook University;
9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   1 of 25
A Central Question of our Field




                           Roy A. Lacey, Stony Brook University;
        9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   2 of 25
Quantitative study of the phases of QCD is Central to our goal!

                                                Big         Bang

                                                                “The major discoveries in
                                                                  the first five years at
                                                               RHIC must be followed by a
                                                                broad, quantitative study
                                                                   of the fundamental
                                         p                       properties of the quark
                                                                     gluon plasma …”
                                                               The Frontiers of Nuclear Science
                                                                  A Long Range Plan - 2007



                                                                       Characterization requires
                                                                        T, cs, q, , 
                                                                               ˆ                        etc ?
The extraction of transport coefficients is crucial to the heavy ion
              programs at both RHIC and the LHC
                                             Roy A. Lacey, Stony Brook University;
                          9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011     3 of 25
   The Flow Probe
                                            Smooth Geometry
            1 1 dET
  Bj 
           R 2  0 dy           y 2  x2
                         2 
 ~ 5  15
          GeV                    y 2  x2
           fm3
                                                                        Control parameters  , cs ,  , T, T f
           Bj  
 P  ²         
                   s/                                         Geometry characterized by many harmonics
                              Actual Collisions




                                                                                 r cos  n part   r sin  n part 
                                                                                                         2                            2
   Flow reflects the propagation of                                                n                               n

 several sound modes in the medium                                      n 
                                                                                                             n 2
                                                                                                         r
                                    2 2 t 
                                              T  0 
                               T  t , k   exp 
                                       k
                                   3 s T 
            Flow measurements are important probes for transport coefficients
                                                                 Roy A. Lacey, Stony Brook University;
                                              9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   4 of 25
 Quantifying Flow
                                                                                Azimuthal Distribution
                                                                                    
                                                                                                          
                                                                      f ( )  1  2 vn cos(n  n n ) 
                                                                                    n 1                 
                                                                                         2
                                                                     e    ein f ( )d  vn ein n
                                                                          in
                                                                                        0
                                                                                        in ( p  n )
                                                                       vn          e                    , n  1, 2,3..,
                                                                      dN pairs                         
                                                                               1   2vn vn cos(n ) 
                                                                                         a b

                                                                       d       n1                   

                                                                      For smooth profile     
         r n cos  n part   r n sin  n part 
                           2                         2

  n                                                                     Odd harmonics = 0
                                n 2
                            r

Initial geometry and its attendant fluctuations
                                                                          For "lumpy" profile     
          Drive momentum anisotropy                                               Odd harmonics ≠ 0

                                                              Roy A. Lacey, Stony Brook University;
                                           9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   5 of 25
      High precision data is central to the
      extraction of transport coefficients

  Precision validated via Comparisons between:
 Different experiments
    Different methods within an experiment
    Different event plane η’ separation
    etc.




                                           Roy A. Lacey, Stony Brook University;
                        9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   6 of 25
   Measurements                                               Schematic Detector Layout



ZDC/SMD             FTPC             TPC                      FTPC
                                                                                ZDC/SMD



                                                          2.5 <|η|< 4.0           |η| > 6.3
                                   |η| < 1.3
           STAR

   Correlate hadrons in central Arms                    ∆φ correlation function for EPN - EPS
     with event plane (RXN, etc)
                                                          dN pairs                         
                                                                   1   2vn vn cos(n ) 
                                                                             a b
 dN                                                     d     n1
              
       1  2 vn cos  n(  n )  (I)                                                   (II)
 d          n 1                   
                                                            ∆φ correlation function for EP - CA
vn { n }  cos n   n  , n  1, 2,3..,
                          

                      STAR also exploits the cumulant technique
                                                      Roy A. Lacey, Stony Brook University;
                                   9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   7 of 25
   Measurements                                                   Schematic Detector Layout
                         Central Arms (CA) |η’| < 0.35
                              (particle detection)
                                                                                        ψn    RXN(||=1.0~2.8)
                                                                                             MPC (||=3.1~3.7)
                                                                                             BBC (||=3.1~3.9)




                                                                                     Correlations between
                                                                                       sub-event planes
                                                                                     (EPN - EPS ) can also
                                                                                          be studied!

   Correlate hadrons in central Arms                        ∆φ correlation function for EPN - EPS
     with event plane (RXN, etc)
                                                              dN pairs                         
                                                                       1   2vn vn cos(n ) 
                                                                                 a b
 dN                                                         d     n1
              
       1  2 vn cos  n(  n )  (I)                                                       (II)
 d          n 1                   
                                                                ∆φ correlation function for EP - CA
vn { n }  cos n   n  , n  1, 2,3..,
                          

                                                          Roy A. Lacey, Stony Brook University;
                                       9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   8 of 25
                                                                  RXN                 RXN
    Results: Event plane                                BBC/MPC                            BBC/MPC
       Correlations



   Clear 12 correlation
      well known
   Weak 24 correlation
      well known
   Weak 13 correlation
      Not unexpected
   No 23 correlation
      Large fluctuations of
       ψ3 about ψ2



                     Sub-event correlations give crucial insights and
                       Validates the important role of fluctuations
                                                  Roy A. Lacey, Stony Brook University;
                               9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   9 of 25
Flow Measurements
    Vn (EP): arXiv:1105.3928                            Phys. Rev. Lett. 105, 062301 (2010)




      Good agreement between vn results obtained
     via event plane (EP) and two-particle correlation                             ψn   RXN (||=1.0~2.8)
                                                                                        MPC (||=3.1~3.7)
                       method (2PC)
                                                                                        BBC (||=3.1~3.9)
        No evidence for significant η’ - dependent
           non-flow contributions from di-jets.

                                                  Roy A. Lacey, Stony Brook University;
                               9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   10 of 25
          Flow Measurements

                                                           Comparison of measurements with different ∆η’
                                        FCAL: 3.3<|Ƞ’ |< 4.8 )                                       J. Jia [ ATLAS Collaboration QM 2011
                                   EP method full-FCal                   ATLAS Preliminary
                         0.3
                                   2p D hÎ[0.0,0.5]
                                   2p D hÎ[2.0,3.0]                          ò Ldt = 8 mb   -1



                                   2p D hÎ[3.0,4.0]
                         0.2       2p D hÎ[4.0,5.0]
           v2




                         0.1


                                               0-10%                                                      20-30%                           40-50%
                          0
           2
two-particle v




                         1.4
                 EP v2




                         1.2

                           1

                               1       2      3        4     5   6   7   1          2            3        4    5   6   7   1   2   3       4     5     6     7
                                                  p [GeV]                                            p [GeV]                           p [GeV]
                                                   T                                                  T                                T


                                                                Significant bias from near-side jet for |Δη|<0.5
                                                                Bias for pT>4 GeV due to swing of recoil jet

                                               ∆η’ gap leads to significant reduction of non-flow effects

                                                                                            Roy A. Lacey, Stony Brook University;
                                                                         9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011       11 of 25
Comparing Measurements across experiments


                   EP: 3.1<|η|<3.7




     PHOBOS EP: 2.05<|η|<3.2




               Good agreement between RHIC measurements
                                               Roy A. Lacey, Stony Brook University;
                            9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   12 of 25
Comparing Methods Across Experiments




      Different methods reflect different sensitivity to fluctuations
                     This is now well understood !!
                                          Roy A. Lacey, Stony Brook University;
                       9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   13 of 25
Results: vn(ψn)
                                          http://arxiv.org/abs/1105.3928




                                                             v4(ψ4) ~ 2v4(ψ2)
        Mild centrality dependence for the higher harmonics
                    Important role of fluctations
                                        Roy A. Lacey, Stony Brook University;
                     9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   14 of 25
Results: vn(ψn)




                                     Roy A. Lacey, Stony Brook University;
                  9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   15 of 25
Beam Energy Dependence of vn




          v2,3,4 saturates for the range √sNN 39 - 200 GeV
                 vn similar at much higher energies
                                        Roy A. Lacey, Stony Brook University;
                     9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   16 of 25
    Insights from “hydrodynamic” scaling
        patterns and their implication!

Flow is pressure driven
Flow is partonic
Flow is acoustic
   new constraints for:
      η/s
      initial geometry
      viscous horizon
      sound horizon



                                     Roy A. Lacey, Stony Brook University;
                  9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   17 of 25
 Flow is partonic                                                                    v3 PID scaling


   Flow is pressure
        driven


KET &  nq  scaling
           n /2


 validated for v3
  Partonic flow                                                                         v4 scaling

Reminder
                                                    v2 scaling
                                    Baryons



                              Mesons                   Phys. Rev. Lett. 98,
                                                        162301 (2007)




                  Consistent partonic flow picture for vn
                                                 Roy A. Lacey, Stony Brook University;
                              9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   18 of 25
Flow is partonic




                   KET & nq scaling validated for v2 for
                    Broad range of particle species!

                                              Roy A. Lacey, Stony Brook University;
                           9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   19 of 25
Constraints for η/s

Hydrodynamic Model Comparison
                             Song et al. arXiv:1011.2783




             
        4        1  2.5
             s                      Small specific viscosity
                                    Model uncertainty dominated by ε

                                                  Roy A. Lacey, Stony Brook University;
                               9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   20 of 25
                                                                       Calculations:
New constraints for εn and η/s                        B. Alver et. al., Phys. Rev. C82, 034913(2010).
                                                      B. Schenke et. al., Phys. Rev. Lett. 106, 042301(2011).
         http://arxiv.org/abs/1105.3928               H. Petersen et. al., Phys. Rev. C82, 041901(2010).




              v3 breaks the ambiguity between CGC vs. Glauber
                           initial conditions and η/s
                                             Roy A. Lacey, Stony Brook University;
                          9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   21 of 25
Flow is acoustic

 Viscous parameterization
                               (a)

                                                                                      2 2 t                
                                                                T  t , k   exp    k                     T  0 
                     0.6
                                                                                     3 s T                  
                                                                                                      n
                                                                        Deformation                k
                                                                                                      R
                2



                     0.4
               v2/




                     0.2


                                                                                                      Approx.
                                      Data
                     0.0
                           0         100   200     300
                                           Npart                         Acoustic Scaling

     Higher-order harmonics should scale as a power of v2

                                                          Roy A. Lacey, Stony Brook University;
                                       9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   22 of 25
Acoustic scaling
                            Scaling observed for vn/(v2)n/2




                      ! Viscous effects cancel !
                   Same scaling observed at the LHC
                                          Roy A. Lacey, Stony Brook University;
                       9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   23 of 25
Implications of Acoustic scaling                             Cancellation of viscous effects
                                                             allow constraint for eccentricity


                       2 2 t   
 T  t , k   exp    k        T  0 
                      3 s T     


 Specific predicted dependence
             of vn/εn


New constraints from acoustic scaling
         Glauber eccentricity                                                    0.1


         4πη/s ~ 1.4




                                                                            n
                                                                           vn/
         rv ~ 1.9 fm                                                            0.01


         Hs ~ 4.0 fm
         Similar estimates for LHC                                          0.001
                                                                                        2      4        6          8
                                                                                                   n


                                                                                        Viscous Horizon (rv)
                                                        Roy A. Lacey, Stony Brook University;
                                     9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011       24 of 25
summary                                               Phys.Rev.Lett.98:092301,2007

Flow harmonics (odd & even)
 provide new and compelling
  constraints for extracting
the properties of the strongly
  coupled plasma created in
    RHIC & LHC collisions

  Experimental program at
   RHIC is well launched
                   
     4 : 1.4       
           s                     Validation of the Acoustic character of flow
                        
       ~ 0.3 fm                is very important !!
                        
      rv : 1.9 fm                Provides important additional
      H s ~ 4.0 fm              constraints for initial state models
                                and several properties of the QGP
      T f ~165  11 MeV         Further detailed model calculations required!
                        
                        
                                               Roy A. Lacey, Stony Brook University;
                            9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   25 of 25
        End




                   Roy A. Lacey, Stony Brook University;
9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   26
     Scaling constrains η/s




                                                                 Demir et al
 η/s from hadronic phase
is very large 10-12x(1/4π)
No room for such values!

     Partonic flow dominates!
Hadronic contribution cannot be large


                                                 Roy A. Lacey, Stony Brook University;
                              9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   27 of 25
Precision Data

                                                   Preliminary, STAR, PHENIX and E895 data




 Excellent agreement between experiments for the excitation function!
         Crucial for η/s extraction and the critical point search

                                             Roy A. Lacey, Stony Brook University;
                          9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   28 of 25
Viscosity Extraction

         Relativistic viscous hydrodynamical calculations
                                                                              /s ~ 0



                                                                               /s = 1/4




                                                                                /s = 2 x 1/4


                                                                                /s = 3 x 1/4


           1 
                  1.3  1.3 (theory)  1.0 (experimen t)
         s   4 

                                               Roy A. Lacey, Stony Brook University;
                            9th Workshop on QCD Phase Transitions and RHIC, Hangzhou, China, July, 2011   29 of 25

								
To top