production - wayne state universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfsummary...
TRANSCRIPT
![Page 1: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/1.jpg)
Robert Pak (BNL) WWND 2013 0
production @
Ro
Robert Pak
for PHENIX Collabora0on
![Page 2: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/2.jpg)
• Knobs to turn: – Centrality, Npart – Collision energy, √sNN – In-medium path length, L, using event plane
• Observables: – xT scaling of invariant yield – Nuclear modification factor, RAA – Fractional momentum loss, Sloss – Elliptical flow, v2
• Model comparisons • Summary • Acknowledgements
Robert Pak (BNL) WWND 2013 1
![Page 3: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/3.jpg)
π0 invariant mass
Robert Pak (BNL) WWND 2013 2
PRC 80, 054907 (2009)
![Page 4: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/4.jpg)
η-meson to π0 ratio
Robert Pak (BNL) WWND 2013 3
arXiv:1208.2254v2
• For constant fit to min. bias data: η/π0 = 0.45 +/- 0.01
• Similar to d+Au (0.47 +/- 0.03) and p+p (0.48 +/- 0.03)
• Lack of nuclear effects at high pT indicates fragmentation occurs outside the medium
![Page 5: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/5.jpg)
π0 invariant yields
Robert Pak (BNL) WWND 2013 4
PRL 101, 232301 (2008)
![Page 6: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/6.jpg)
xT = 2pT/√s scaling
Robert Pak (BNL) WWND 2013 5
E d3!dp3
=1
sneff xT , s( )
G(xT )
In hard scattering region:
universal scaling function
For isolated photons from p+p collisions in Bjorken’s parton model:
neff = constant = 4.0
PRD 86, 072008 (2012)
![Page 7: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/7.jpg)
xT scaling (cont)
Robert Pak (BNL) WWND 2013 6
neff xT( ) =log Yield xT , s1( ) Yield xT , s2( )( )
log s2 s1( )
In pQCD contributions from: • running αs(Q2) • PDF (and FF) evolution Other effects: • kT smearing • higher-twist phenomena So neff not constant, rather:
Largest deviation for 39 and 200 GeV Au+Au comparison hard scattering not dominant source of high pT π0 in 39 GeV Au+Au collisions
to compare different beam energies.
PRL 109, 152301 (2012)
![Page 8: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/8.jpg)
nuclear modification factor - RAA
Robert Pak (BNL) WWND 2013 7
PRL 101, 162301 (2008)
n.b., RAA requires p+p reference data at corresponding √s.
![Page 9: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/9.jpg)
q ̂from PQM
Robert Pak (BNL) WWND 2013 8
PRC 77, 064907 (2008)
Early attempt to extract transport coefficient q ̂using a parton quenching model
![Page 10: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/10.jpg)
arXiv:1208.2254v2
more recent π0 invariant yields
Robert Pak (BNL) WWND 2013 9
![Page 11: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/11.jpg)
Robert Pak (BNL)
RAA @ 200 GeV
WWND 2013 10
arXiv:1208.2254v2
![Page 12: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/12.jpg)
fit the data
Robert Pak (BNL) WWND 2013 11
Above Npart = 167 slope of linear fit is significantly different from zero
![Page 13: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/13.jpg)
cf., ALICE
Robert Pak (BNL) WWND 2013 12
• Similar suppression for 14x increase in colliding energy at LHC ~2x increase in parton density at LHC
• Slope in PHENIX data comes as no surprise
arXiv:1208.2711v1
![Page 14: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/14.jpg)
fractional momentum shift
Robert Pak (BNL) WWND 2013 13
Partons in 200 GeV collisions suffer largest average momentum loss
PRL 109, 152301 (2012)
arXiv:1208.2254v2
![Page 15: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/15.jpg)
Sloss (= δpT/pT) vs. centrality
Robert Pak (BNL) WWND 2013 14
![Page 16: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/16.jpg)
Sloss @ PHENIX, cf., ALICE
Robert Pak (BNL) WWND 2013 15
arXiv:1208.2254v2
![Page 17: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/17.jpg)
model comparisons
Robert Pak (BNL) WWND 2013 16
• AMY: Arnold, Moore & Yaffe, JHEP 0206, 030 (2006)
• HT: X.N. Wang & X. Guo, NPA 696, 788 (2001)
• ASW: Salgado & Wiedemann, PRD 68, 014008 (2003)
• Parton energy loss models incorporated into same 3D hydro calculation
• No distinguishing power despite differences in q ̂
![Page 18: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/18.jpg)
Robert Pak (BNL) WWND 2013 17
pseudorapidity
![Page 19: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/19.jpg)
Robert Pak (BNL) WWND 2013 18
flow participants
spectators
• More recently, generalized eccentricities for higher flow moments:
• Measured values must be
corrected by event plane resolution:
![Page 20: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/20.jpg)
RAA vs. event plane
Robert Pak (BNL) WWND 2013 19
arXiv:1208.2254v2
![Page 21: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/21.jpg)
centrality dependence
Robert Pak (BNL) WWND 2013 20
3.4 fm
6.1 fm
6.7 fm
5.9 fm • Suppression increases
with centrality • In-plane suppression
less than out-of-plane • Average path length in
medium changes more in-plane than out-of-plane difference in RAA becomes larger as centrality decreases
• All in agreement with: PRC 80, 054907 (2009)
![Page 22: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/22.jpg)
RAA vs. event plane, cf., hydro models
Robert Pak (BNL) WWND 2013 21
arXiv:1208.2254v2 Greater sensitivity in-plane:
cubic L dependence
![Page 23: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/23.jpg)
in-medium path length dependence
Robert Pak (BNL) WWND 2013 22
PRL 105, 142301 (2010)
![Page 24: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/24.jpg)
more hydro comparisons
Robert Pak (BNL) WWND 2013 23
Majumder & C. Shen PRL 109, 202301 (2012)
Progress extracting q ̂for comparison to LHC
![Page 25: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/25.jpg)
mesons
baryons
Robert Pak (BNL) WWND 2013 24
PRL 98, 162301 (2007)
same mass scaling pattern as seen in 200 GeV Au+Au collisions
√sNN dependence of PID v2
preliminary preliminary
![Page 26: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/26.jpg)
Robert Pak (BNL) WWND 2013 25
quark number (nq) scaling indicates partonic collective flow down to 39 GeV
Phys. Rev. Lett. 98, 162301 (2007)
mesons
baryons
PID v2/nq
preliminary preliminary
![Page 27: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/27.jpg)
more recent PID v2
Robert Pak (BNL) WWND 2013 26
PRC 85, 064914 (2012)
• New TOF patch installed to extend PID
• quark number scaling breaks down at higher pT
Au+Au √sNN = 200 GeV
![Page 28: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/28.jpg)
Summary • Onset of hard processes at high pT from xT scaling • Onset of suppression from RAA vs √sNN
– PHENIX data provides a bridge to RAA @ LHC
• Sloss (= δpT/pT) increases with Npart and √sNN
• In-medium path length dependence > L2 for parton energy loss
• Progress to extract q̂ through model comparisons • From PID collective flow in Au+Au collisions:
– partonic flow (with perfect fluidity) down to 39 GeV – quark number scaling breaks down at higher pT
Robert Pak (BNL) WWND 2013 27
![Page 29: production - Wayne State Universityrhic.physics.wayne.edu/~bellwied/wwnd2013/wwnd2013-pak.pdfSummary • Onset of hard processes at high p T from x T scaling • Onset of suppression](https://reader033.vdocuments.us/reader033/viewer/2022042220/5ec6ba01192bac520a09ac84/html5/thumbnails/29.jpg)
Robert Pak (BNL) WWND 2013 28