Future measurements in jet tomography at RHIC energies
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Transcript of Future measurements in jet tomography at RHIC energies
Workshop on Future Prospects in QCD at High Energy
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Future measurements in jet tomography at RHIC energies
Single particle as probe Jet correlation as probe
Jiangyong Jia
Thank Takao, Zhangbu Xu for providing useful input
Jiangyong Jia 2
Interaction between jet and Medium
Central Collision Peripheral Collision
Jiangyong Jia 3
Handles of Jet tomography Single particle spectra
PID spectra out to high pT (0±, , k, p,) * Direct photon. * Heavy flavor to high pT (NP-electron, Dk) * *
Jets 2-particle correlation in and * – h correlation. * Identified – identified correlation * Heavy flavor – hadron correlation (e-h, D-h). * Multi-particle correlation * Full jet reconstruction (-jet, HQ-jet) *
Variables to explore pT, centrality and dependence. Reaction Plane dependence (or v2 in single particle case) Species dependence (Cu+Cu, Au+Au, U+U, A+B). Energy dependence (sps energy 200 GeV)
Reference p+p, p+A
* Precision measurement* Exploratory measurement
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Upgrades (STAR) Barrel Time of Flight (TOF): Particle ID (e, hadrons)
Current prototype patches to be upgraded to full azimuth, -1 < < 1. Project is funded and proceeding
Heavy Flavor Tracker (HFT): Displaced vertices High precision (<10 um) measurements for displaced vertices Goal: standalone detector in place for RHIC run in 2009
Barrel Electromagnetic Calorimeter (EMC): High pt (e,)
¾ barrel of run 5 has been instrumented to full azimuthal coverage, -1 < < 1, for next RHIC run: COMPLETE
Forward Meson Spectrometer (FMS): Low x physics Full azimuthal EM Calorimetry 2.5 < < 4.0 Possibility of charm measurements in this region Project is proceeding: complete by next d+Au run
Data acquisition upgrade (DAQ1000): Data rate 10x Upgrade TPC readout an order of magnitude, ~double effective Luminosity Target for completion: RHIC run in 2008
J. Dunlop 2005
Large coverage, and fantastic PID, Heavy flavor capabilities and high DAQ rate
Existing detectors will gain hugely from DAQ upgrade and RHIC II luminosity : TPC and Barrel EMC.
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NCCNCC
MP
C
MP
C
VTX & FVTX
-3 -2 -1 0 1 2 3 rapidity
cove
rage
2
Cen
tral
arm
Cen
tral
arm
Upgrades (PHENIX)
New large coverage with NCC/MPC for 0, direct and RP. silicon detectors provide precision vtx tracking for Heavy favor. Temporary RxNP detector for good RP measurement. Extended pT for 0 and direct with EMCal Extended pT reach for , k, p with RICH/AEROGEL.
RxNP (2006-2009)
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Upgrades and RHIC-II
RHIC II
FY 2012 FY 2013FY 2011FY 2010FY 2009FY 2008FY 2007FY 2006
RHIC Mid-Term Strategic Plan
LHI
LP4
RHIC II CD-0 CD-1 CD-2 CD-3 CD-4
PHENIX + STAR
Hi Rate DAQ 1000
PIDHBD
TOF
VTX
Forward
FMSMu Trigger Nose Cone Calorimeter
EBIS
Heavy Ion Luminosity
SPIN F.O.M.
e-pair spectrum
Open Charm
Jet TomographyMono-Jet
U+U
PHENIX STAR
G/GTransversity and P-V W± prod.
PHENIX & STAR VTX upgrades
STAR forward tracking
RHIC II
FY 2012 FY 2013FY 2011FY 2010FY 2009FY 2008FY 2007FY 2006
RHIC Mid-Term Strategic Plan
LHI
LP4
RHIC II CD-0 CD-1 CD-2 CD-3 CD-4
PHENIX + STAR
Hi Rate DAQ 1000
PIDHBD
TOF
VTX
Forward
FMSMu Trigger Nose Cone Calorimeter
EBIS
Heavy Ion Luminosity
SPIN F.O.M.
e-pair spectrum
Open Charm
Jet TomographyMono-Jet
U+U
PHENIX STAR
G/GTransversity and P-V W± prod.
PHENIX & STAR VTX upgrades
STAR forward tracking
Near term RHIC-IIRUN7
RHICII 20 – 40 times gain in recorded luminosity But we should continue making discoveries in next few
years PHENIX can have x10 RUN4 AuAu stat. in 25 weeks running and
x10 RUN3 dAu stat. in 10 weeks running. Besides some upgrades will be completed. We can do low energy/species scan.
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Single particle suppression
Calibrated probe: pQCD + factorization theorem
Experiment measurement well controlled
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High pT v2 approach the radiative eloss limit
AMYPQM
v2 come from pQCD jets?
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Theoretic descriptions pQCD initial geometry + jet quenching dynamic
geometry RAA depends on both TAB and p(E). Many types of p(E) can be tuned to match data.T. Renk hep-ph/0607166
All leads to surface emission but the details are differentHide behind the data error bar.
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Centrality dependence Two very different eloss models give equally good description
P(E) = (E/E – f) – shift in pT P(E) = p0 (E)+(1-p0) (E-E) – shift down in yield.
Centrality dependence has little constrain on energy loss model?
More complicated energy loss of X.N.Wang, I. Vitev, PQM, etc gives the same results.
A.Drees, H.Feng and J.Jia,Phys.Rev.C71:034909,2005
PHENIX White paper
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qhat puzzle qhat <E>, however RAA depends not just on the average (<E/E>)
and but the actual distribution! (p(E,r))A model with smaller <E/E> but narrower p(E) width could lead to larger
suppression!! (nucl-th/0512076)
1( )
nT
P Ep
E E/E
E/E
E>5 GeV/c
5-14 GeV2/fm (Wiedemann/Salgado),
0.35-0.85 GeV2/fm (GLV),
2 GeV2/fm (AMY),
few GeV2/fm (X.N. Wang/Majumder)
Note: ADS/CFT 3-15 GeV2/fm, hep-ph/0605178 (factor of 3 smaller according to hep-ph0605158)
Models are tuned to match the central data, leading to different average qhat (<E/E>)
Should compare directly p(E)?
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Future measurements on hadron spectra
Precision measurements of 0,k,p () at higher pT Constrain different eloss models, and within same model, the qhat. PID at high pT probe gluon/quark eloss & suppress the recombination effect
Precision measurement of the direct production at intermediate and high pT. Crucial input for -jet analysis Study various medium induced direct , they do not scale with Ncoll.
Turbide et.al PRL 96 032303 (2006)
Estimate with x8 statistics for PHENIX by T. Sakaguchi
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Gluon vs. quark jet
Hint of deviation from eloss prediction
High statistic pp, dAu, AuAu and higher reach in pT are desirable
STAR: nucl-ex/0606003
pbar: gluon jetsp: gluon/quark jets, pT dependent
Hadron identification: STAR Collaboration, nucl-ex/0309012
Log10(p)
Log
10(d
E/d
x)
STAR TOF & TPC 0.5-15 GeV/c for , p separation , Ks out to very high pT via topological decay
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Future measurement on hadron V2 Precision measurements on the hadron and direct v2
Where is the end of recombination region (quark number scaling breaking?) Will the v2 consistent with energy loss at highest pT? (constant?)
PHENIX RxNP detector greatly improve the RP resolution, by almost factor of 2
BBC
RxNP
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Future measurements on direct v2 Difference sources have different v2
Primary v2=0, thermal v2>0, fragmentation v2>0, brem and conversion v2<0
Thermal v2
R. Chatterjee et.al PRL.96:202302,2006
Brems and conversion v2
Turbide et.al PRL 96 032303 (2006)
(T. Sakaguchi)
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Heavy quark eloss Surprisingly similar suppression level of electron as light
mesons. Radiative Eloss (before 2005) + Elastic Eloss (Mustafa, wicks et.al, Djordjevic)
+ multi-body interaction.
All with similar magnitude
Importance of multi-body interaction break down of pQCD in sQGP?
Elastic are important for light mesons! Nucl-th/0512076
C.M. Ko, HardProbe 2006
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Heavy quark flow Non-photonic electron flow indicate strong medium interaction. Competing mechanisms: Energy loss vs. Recombination
If RAA same as pion v2 is the same as at high pT ? Intermediate pT will the D, B meson follow quark number scaling?
Hendrik, Greco, Rappnucl-th/0508055
w.o. B meson (c flow)w. B meson (c,b flow)
?
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Future improvements Charm and bottom quarks : DIFFERENT PDFs, cold nuclear effects,
fragmentation/recombination and eloss pattern. Complicates the physical interpretation of spectra and v2. Separate c and b via displaced vtx STAR HFT, PHENIX VTX upgrade. Reach higher pT with the increased statistics from RHIC II.
Large uncertainty on crossing point
S. Wicks, WH, M. Gyulassy, and M. Djordjevic, nucl-th/0512076
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High stat. NP-decay electron measurement, focus on high pT Can reduce the photonic contribution with silicon detectors High pT: increase signal/bg, dominated by b quarks
VTX : statistically separate D/B
PHENIX
D v2 is possible, need 70-140M
Displaced vertex tagging or hadronic decay: spectra and v2
STARPHENIX RUN4
RUN2
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A confluent of away-side jet informationlow pT
Moderate high pT
What is the picture?
4-6 x 2-4 GeV/c
pT,assoc 0.2 GeV/c
Phys. Rev. Lett. 90, (2003)
Phys.Rev.Lett.95,2005
nucl-ex/0604018
STAR
STAR
Intermediate pTnucl-ex/0507004
high pT
STAR
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Trigger and associated pT
Aw
ay jet
I AA
Thermallized gluon radiation
Shock wave or cherenkov? Recombination, Jet brodening
Punch through jets or tangential contribution?
What is the picture?
T 3T
I II III IV
Interplay between jet quenching, medium response and surviving jets!?
Theory: Need quantitative and unified descriptionExperiment :Need systematic/precision measurement
Low pT Moderate high pTIntermediate pT high pT
Increase pt or
merging or punchthough?
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Mach shock: No, Yes, Yes, maybe?
U. Heinz, nucl-th/0503028
Mach cone but not necessarily Mach peaks
J. Casalderrey-Solana hep-ph/0602183,
depends on how one model jet core
which can’t be treated hydrodynamically. No unique solution to hydro equation
G. Ma et.al. nucl-th/0601012, AMPT model (parton cascade = 10mb) shows Mach peaks.
ADS/CFT: hep-th/0605292, hep-th/0606266
how well can one relate hard process in SYM with QCD?
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Di-jets at high pT
Near side jet yield is constant with centrality.Clear away side peak but increasing surpressed
8 < pT(trig) < 15 GeV/c pT(assoc)>6 GeV, nucl-ex/0604018
STAR
d+Au Au+Au 20-40% Au+Au 0-5%
Tangential emission
T. Renk
Punch through
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Challenges of jet correlation measurement
Control background subtraction
Underlying event level : . – mostly use ZYAM approach What v2 value to use? – non flow effects etc. Two source model assumption : <v2
tv2a>=? <v2
t><v2a>
Trigger bias. Bias is more complicated than single particle. hard to constrain models (per-trigger-yield may not be a clean variable).CF = J() + (1+2v2
tv2a cos2)
T. Renk HP2006
Leading dijets
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Thus direct -jet as probe
a a b b AAAA AA AA AA
coll pp
PairsI R I R
N Pairs
Suppression is on the PAIRS!
A simple case : type a has contribution from recombination, type b come only from jet. Then
1 1a bAA AAI while I
RAA IAA of direct
T. Renk hep-ph/0607166
Clear sensitivity using -jet correlation No suppression of leading , IAA = RAA=0.2!!
We know hadron IAA
is close to RAA
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Direct -jet No trigger bias.
Caveat: thermal, fragmentation, bremstrahlung, conversion , depends on geometry not Ncoll Clean tagging of is difficult in AuAu
Rely on statistical subtraction of -h and -h correlations. Sensitive to ratio pp, dAu measurement difficult:
-h-h
0-20%
5-10 x 3-5 GeV/c
1incl decay direct decay 0. ,direct decay isolation tagging
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Future expectation
Ldt pp equivalent N(>5) N(>6) N(>7) N(>8) N(>10)
Run4 AuAu 241mb-1 10pb-1 16k 5.5k 2.2k 1.2k 345Run5 CuCu 3nb-1 12pb-1 19k 6.6k 2.6k 1.4k 414Run5/6 pp 15pb-1 15pb-1 24k 8.3k 3.3k 1.7k 0.5k
RHIC-II x20 200pb-1 320k 110k 44k 24k 7k
Current direct -h correlation signal is marginal Need go higher pT and expand acceptance
Au+Au statistics and upgrades (NCC/VTX) are crucial. STAR will have more stats. But need improve the ability to distinguish decay and prompt photon.
Case study for PHENIX
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Reaction plane dependence of jet correlation
v2 varies in a predictable way Can use it to constrain flow background subtraction! Since near side modification is small at high pT, one can use it to constrain the path length dependence of away side suppression.
D. Winter, WWND2006STAR, PRL 93 (2004) 252301
J. Bielcikova et al, PRC69:021901, 2004
• PHENIX RxNP/NCC, STAR many detectors can provides excellent RP measurement• Have to deal with the non-flow effect
RxNP
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Three particle correlation: Bending or Mach Cone?
away – deflected = -0.04 ± 0.06 (stat) ± 0.09 (syst)away – cone =
0.13± 0.06 (stat) ± 0.05 (syst)
Au+Au 0-10%
Δ12
Δ13
* 0180
* 00.0
0110
= 0 Cent=0-5%
PHENIX Preliminary
*
2
*
12
13*
12 13
p1
p2 p3
Δ12
Trigger
Δ13
More statistics is needed!New kinematical region: trigger on dijets (2 high pT particles) correlate with the third
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correlation and “Ridge” observation
d+Au, 40-100% Au+Au, 0-5%
3 < pT(trig) < 6 GeV2 < pT(assoc) < pT(trig)
Correlation with large gap(|trig|<1, 2.7<|assoc|<3.9) Near side ridge is consistent with
zero Broad away-side correlation, away side parton swing effect
dN
/d
minbias
F.Q. Wang HardProbe 2006
3 —10 x 0.2 — 2 GeV/c
hep-ph/0411341 Armesto,Salgado,Wiedemann
Systematic study of dependence (STAR/PHENIX upgrade)
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Ridge characteristics
Particles in the ridge has similar shape Ridge yields are similar to inclusive single particle:
similar slope, large p/ ratio. Puzzling Results. Control of the background subtraction is important.
Future PID jet correlations help to clarify the picture
preliminary
pt,assoc. > 2 GeV
Au+Au 0-10%
Assoc. ProtonsAssoc. PionsAssoc. h
STAR
J. Putschke HardProbe 2006
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Fully Identified Jet Functions
Away side jet shapes are similar
hadronhadron – Meson Meson vs. vs. hadronhadron –BaryonBaryon
PHENIX Preliminary
p/ ratio in the jet
•Particle composition in the jet modified by medium?•Qualitatively described by recombination, (R. Fries.PRL.94:122301) but what about the shape?
PID correlation
Competing physics make the interpretation difficult. Lacking systematical study in broader kinematical region. Both STAR and PHENIX can extend the measurement to large pT.
We can learn more together with PID spectra measurement.
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Baseline understanding in d+Au
Low x physics (CGC) in forward region via spectra and correlation Cold nuclear energy loss via 0 (PHENX), PID (STAR) xg(x) via direct (PHENIX EMCal/NCC) via 00+X (STAR FMS)
STAR PHENIX PHENIXMid-forward correlation
0 RdA at =0 Direct RdA at =0
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Other Possibilities
Heavy flavor correlation (D-h, e-h) e-h correlation constrains charm and
bottom contribution X. Lin hep-ph/0602067
STAR
Energy scan to study the onset of jet quenching Single spectra, jet correlation Note: many competing mechanisms are as important!
Species scan to explore different geometry Asymmetric system Cu+Au etc, very different path L dependence.
v2n+1>0, test quark number scaling and jet quenching. U+U collisions, achieve maximum eccentricity and energy density, maximum sensitivity to path L dependence. U. Heinz, PRL94:132301,2005
CERES
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Handles of Jet tomography Single particle spectra
PID spectra out to high pT (0±, , k, p,) * Direct photon. * Heavy flavor to high pT (NP-electron, Dk) * *
Jets 2-particle correlation in and * – h correlation. * Identified – identified correlation * Heavy flavor – hadron correlation (e-h, D-h). * Multi-particle correlation * Full jet reconstruction (-jet, HQ-jet) *
Variables to explore pT, centrality and dependence. Reaction Plane dependence (or v2 in single particle case) Species dependence (Cu+Cu, Au+Au, U+U, A+B). Energy dependence (sps energy 200 GeV)
Reference p+p, p+A
* Precision measurement* Exploratory measurement
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THE END
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Collisional is equal/more important than radiative?
Collisional has smaller <E/E> than radiative, but what is important is the eloss distribution p(E). One should directly compare the RAA.
A model with smaller <E/E> but narrower p(E) with could lead to larger suppression
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STAR: direct separation of c,b. STAR: Dk. STAR: > factor 10 improvement in NPE via HFT.
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Control of the background subtraction is important.
RUN2 RUN4
D. Magestro, HP2004
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Does the away side jet disappear at moderately high pT?
Tangential/punchthrough fraction are there?
or
Phys. Rev. Lett. 90, (2003) Phys. Rev. Lett. 95, 2005
STAR 4-6 x 2-4 GeV/c
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PHENIX preliminary
is fixed ! systematic errors fixed! (v4 not included). Path length dependence is small
~ cos(2 )bC
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Shape can be constrained by the RP dependence
Shoulder and dip seen in all bins.
Direct constrains
The dip is significant for bin 4 where the v2 systematic is small.
2 2 2 2t a t av v v v
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How does the medium respond to the jets?
0-5%PHENIX preliminary2.5-4 x 1-2 GeV/c
Other possible mechanisms:Cherenkov radiation, bending jet, Gluon radiation…
QCD Mach cone: cos()=cs/c
x10, 3-4 GeV/c
x3 2-3 GeV/c
1-2 GeV/c
J. Casalderrey-Solana hep-ph/0602183
T=200MeV
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Two particle correlation with large gap
Near-side consistent with zero, No ridge within large error.
Forward particles have large Pz,Pz = 2 GeV/c for pT = 0.2 GeV/chard to generate from flow.
Broad away-side correlation. Away side parton swing effect
|trig|<1, 2.7<|assoc|<3.9
3<pTtrig<10 GeV/c, 0.2<pT
assoc< 2 GeV/c
dN
/d
bkgd subtracted
minbias
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PHENIX: Cu+Cu high pT Jet Correlations
Di-jet signal persists even for the most head-on Cu+Cu collisions.
May allow better determination of matter properties!
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(Dave Morrison)
Npart
Ncoll
eccentricity
b(fm)
At RHIC we can turn quite a few “knobs” by varying the energy, species and
making asymmetric collisions
One of RHIC’s Strengths: Play With Geometry
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Large coverage, and fantastic PID, Heavy flavor capabilities Existing detectors will gain hugely from DAQ upgrade
and RHIC II luminosity : TPC and Barrel EMC.
Upgrades (STAR)
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STAR preliminary
p+p→0+X
STAR preliminary
FPD