Workshop on Future Prospects in QCD at High Energy

1

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

Jiangyong Jia 4

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.

Jiangyong Jia 5

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)

Jiangyong Jia 6

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.

Jiangyong Jia 7

Single particle suppression

Calibrated probe: pQCD + factorization theorem

Experiment measurement well controlled

Jiangyong Jia 8

High pT v2 approach the radiative eloss limit

AMYPQM

v2 come from pQCD jets?

Jiangyong Jia 9

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.

Jiangyong Jia 10

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

Jiangyong Jia 11

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)?

Jiangyong Jia 12

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

Jiangyong Jia 13

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

Jiangyong Jia 14

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

Jiangyong Jia 15

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)

Jiangyong Jia 16

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

Jiangyong Jia 17

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)

?

Jiangyong Jia 18

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

Jiangyong Jia 19

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

Jiangyong Jia 20

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

Jiangyong Jia 21

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?

Jiangyong Jia 22

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?

Jiangyong Jia 23

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

Jiangyong Jia 24

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

Jiangyong Jia 25

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

Jiangyong Jia 26

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

Jiangyong Jia 27

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

Jiangyong Jia 28

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

Jiangyong Jia 29

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

Jiangyong Jia 30

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)

Jiangyong Jia 31

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

Jiangyong Jia 32

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.

Jiangyong Jia 33

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

Jiangyong Jia 34

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

Jiangyong Jia 35

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

Jiangyong Jia 36

THE END

Jiangyong Jia 37

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

Jiangyong Jia 38

STAR: direct separation of c,b. STAR: Dk. STAR: > factor 10 improvement in NPE via HFT.

Jiangyong Jia 39

Control of the background subtraction is important.

RUN2 RUN4

D. Magestro, HP2004

Jiangyong Jia 40

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

Jiangyong Jia 41

PHENIX preliminary

is fixed ! systematic errors fixed! (v4 not included). Path length dependence is small

~ cos(2 )bC

Jiangyong Jia 42

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

Jiangyong Jia 43

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

Jiangyong Jia 44

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

Jiangyong Jia 45

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!

Jiangyong Jia 46

(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

Jiangyong Jia 47

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)

Jiangyong Jia 48

STAR preliminary

p+p→0+X

STAR preliminary

FPD