hadron physics at rhic

Hadron Physics at RHIC

o RHIC Physics

o Low x Saturation?

o Access to Nucleon Structure?

pQCD vs Experiment

o Proton Spin Structure

RHIC and Experiments Gluon Spin Transverse Spin STARSTAR

pp2pppp2pp

M. Grosse Perdekamp UIUC and RBRC

Observables in Antiproton-Proton Interactions and their Relevance to QCD

Hadron Physics at RHIC 2 July 6th

Physics at the Relativistic Heavy Ion Collider

o Quark Matter at high Temperatures and Densities

ion-ion collisions (Cu-Cu, Au-Au: √sNN=22.5, 62, 130, 200 GeV)

o Proton Spin Structure

polarized proton-proton collisions (p-p: √s=200 to 500 GeV)

o Low-x and high parton densities

ion-deuteron collisions (d-Au: √sNN=200 GeV)

very active field: eg. 76 Physical Review Letters in the first 5 years with more than 6800 citations in SPIRES


available channels

jets, hadrons, photons, photon-jet, heavy flavor

Single spin lepton asym-metries in W-production, Lambda production

(1) AN

(2) ATT in Collins- and Interference-Fragmentation(3) ATT and AT In Drell Yan

goals

determine first moment ofthe spin dependent gluondistribution.

flavor separation of quarkand anti-quark spin distributions

measurement of trans-versity and Sivers distributions

Proton Spin Structure in Polarized p-p Collisions at RHIC

qTfq

1,

qq ,

G


Structure of Neutron Stars

physics goal

to find quark matter and survey it’s properties

experimental method

heavy ion collisions at high energies

Heavy Ion Physics


Heavy Ion Physics

A brief history of Heavy Ion Experiment Bevalac AGS GSI SPS RHIC LHC

Find quark matter andsurvey it’s properties


RHIC 2001 – 2005 : the sQGP !

Key Observations

1. Jets are suppressed in central Au + Au collisions– Suppression is flat up to pt ~ 10 GeV/c– Absence of suppression in d+Au

2. Strong elliptic flow– Scaling of v2 with eccentricity shows that a high degree of collectivity

builds up at a very early stage of collision – evidence for early thermalization

– Data described by ideal hydrodynamic models fluid description of matter applies.

3. Energy density allows for a non-hadronic state of matter– Energy density estimates from measurements of dN/dy are well in

excess of the ~1 GeV/fm3 lattice QCD prediction for the energy density needed to form a deconfined phase.

Strongly interacting Quark Gluon Plasma !

Is the Initial State in Heavy IonCollisions Determined by Saturation

Effects in the Gluon Field ?


BRAHMS, PRL 93, 242303 and R. Debbe

RdAu= YdAu

NcollYpp

BRAHMS d+Au Results as Function of Rapidity and Centrality

Hadron production is suppressed at large rapidityconsistent with saturation effects at low x in the Au gluon densities CGC


PRL 94, 082302

Suppression in the d direction and enhancement in the Au frag. region

Similar Effects Seen by PHENIX and PHOBOS

Hadron Physics at RHIC 10

July 6th

Saturation Picture (CGC) Consistent with Data

A. Dumitriu et al. Nucl. Phys. A770 57-70,2006

Not bad! However, Large K factors, η-dependent. We hope for NLO calculations soon …

Access to Nucleon Structure inHadron Collisions?


July 6th

Access to Nucleon Structure at RHIC

)(),(),(),( xGxqxGxqdp

d

T

Measure: (spin dependent) cross sections

QCD analysis: (spin dependent) distribution functions


July 6th

Example:G(x) from global NLO pQCD analysis using projected future direct photon data from

RHIC

M. Hirai, H.Kobayashi, M. Miyama et al. (Asymmetry Analysis Collaboration)

QCD analysisof inclusiveDIS data

QCD analysisDIS data + futuredirect photons


July 6th

M. Hirai, H.Kobayashi, M. Miyama et al. (Asymmetry Analysis Collaboration)

Does NLO pQCD provide a reliable framework for the interpretation of polarized proton data in terms of

polarized parton distribution functions?

QCD analysisof inclusiveDIS data

QCD analysisDIS data + futuredirect photons

Example: ΔG(x) from global NLO pQCD analysis using projected future direct photon data from

RHIC


July 6th

I) Tevatron data as input to CTEQ QCD analysis of hard scattering data, specifically: G(x,Q2)

II) Comparison: NLO pQCD vs RHIC data inclusive hadrons inclusive jets direct photons

Is pQCD applicable in p-p Collisions ?


July 6th

CTEQ Global QCD Analysis for G(x,Q2) and q(x,Q2)

J. Pumplin et.al JEHP 0207:012 (2002)

3.16GeVQ at u

3.16GeVQ at d

10-410-3 10-2 10-1 0.5 x

gluon

down

up-quarks

anti-down

Quark and Gluon Distributions

error on G(x,Q2)

error for u(x,Q2)

+/- 10%

+/- 5% +/- 5%

error for d(x,Q2)

10-410-3 10-2 10-1 0.5 x

CTEQ6: use DGLAP Q2-evolution of

quark and gluon distributions to extract q(x,Q2)and G(x,Q2) from global fit to data sets at different scales Q2.

H1 + Zeus F2

CDF + D0 Jets

CTEQ5M1

CTEQ6M


July 6th

G(x,Q2) and q(x,Q2) + pQCD beautifully agree Tevatron + HERA!J. Pumplin et.al JEHP 0207:012 (2002)

D0 Jet Cross Section ZEUS F2


July 6th

Data vs NLO pQCD at RHIC: Inclusive π0

PHENIX π0 cross section a |η|<0.35 Phys.Rev.Lett.91:241803,2003

STAR π0 cross section a 3.4<η<4.0 Phys.Rev.Lett.92:171801,2004

NLO QCD fromW. Vogelsang


July 6th

Theory calculation show good agreement with the experimentalcross section.

Direct Photons and Inclusive Jets vs NLO pQCD

Inclusive Jet Cross sectionDirect Photon Cross section

STAR Preliminary

PHENIX Preliminary NLO QCD fromW. Vogelsang

NLO QCD fromW. Vogelsang


July 6th

Direct Photons in Heavy Ion Collisions

Use hard probes (hadrons vs directphotons) to study medium formed in heavy ion collisions at RHIC

qg

direct photon

quark jet


July 6th

15 fm b 0 fm0 Npart 394

Spectators

Participants

Npart ~ (No. participants)

Nbinary ~ (No. binary collisions)

Collision Geometry: Impact Parameter vs Collisions and Participants

0 Nbinary 1200


July 6th

pQCD vs Direct Photons in Au+Au

PRL 94, 232301

pQCD x number of binary nucleon-nucleon collisions, Nbinary , in heavy in collisions (Werner Vogelsang)

pQCD calculations permit “calibration” of hard probes in heavy ion collisions at RHIC in a model indepen-dent way


July 6th

pQCD vs Inclusive Hadrons: “Jet Suppresion”

• Suppression is strong (factor 5) up to 20 GeV/c• Medium is extremely opaque• The data provide a lower bound on the initial gluon density

pp comparison data (and pQCD!)


July 6th

RHIC: ion-ion and polarized p-p Collider


July 6th

RHIC five complementary experiments

pp2pppp2pp

Hadron Physics at RHIC July 6th

AGSLINACBOOSTER

Polarized Source

Spin RotatorsPartial Snake

Siberian Snakes

200 MeV Polarimeter

AGS Polarimeter

Rf Dipole

RHIC pC Polarimeters Absolute Polarimeter (H jet)

PHENIX

PHOBOS BRAHMS & PP2PP

STAR

Siberian Snakes

Helical Partial Snake

Strong Snake

Spin Flipper

2005 Complete!2005 Complete!

A novel experimental methodA novel experimental method: Probing Proton Spin Structure Through High Energy Polarized p-p Collisions

high current polarized sourcehigh energy proton polarimetry helical dipoles magnets

Run 2006

∫Ldt ~ 23.5 pb-1

Polarization average 60%


July 6th

2006: Figure of Merit Goals and Actual

P2L: Transverse

P4L: Longitudinal

0.88 1.11

~7 times Run-5

goals


July 6th

100% transverse spin!Two spectrometer armswith good particle ID athigh momenta

BRAHMS: AN for charged π,K, p, low x


July 6th

PHENIX: ∆G, ∆q/∆q, Sivers, δq, low x

Muon IDPanels

CentralArms

North MuonArm

South MuonArm

Ring ImagingCerenkov

EM Calorimeter

Muon TrackingChambers

Beam-BeamCounter

Multiplicity/VertexDetector

Time ExpansionChamber

Drift Chambers

Pad Chambers

Time of FlightPanels

Four spectrometer arms with excellent trigger and DAQ capabilities.


July 6th

STAR: ∆G, ∆q/∆q, Sivers, δq, low x

Large acceptance TPC and EMC -1<η<2


July 6th

RHIC Detector Status and Upgrades

o All instrumentation is in place for the planned measurements on spin dependent gluon distributions and transverse spin.

o W-physics (flavor separation of quark and anti-quark polarizations) requires upgrades in PHENIX (muon trigger, funded by NSF and JSPS) and STAR (forward tracking, grant proposal to DOE in preparation).

o In PHENIX a central silicon tracking upgrade and a forward tungsten silicon calorimeter upgrade will significantly enhance capabilities for jet and photon-jet physics.

o A RHIC luminosity upgrade (RHIC II) for heavy ions with electron cooling will gain a factor 3-5 (beyond design) in luminosity from 2012.

Gluon Spin Distribution ALL in inclusive Jets (STAR) ALL for inclusive π0 (PHENIX)


July 6th

Results limited by statistical precision Total systematic uncertainty ~0.01 (STAR) + beam pol. (RHIC) GRSV-max gluon polarization scenario disfavored

jet cone=0.4

*) Predictions: B.Jager et.al, Phys.Rev.D70(2004) 034010

ALL from Inclusive Jets in p+p Collisions at √s=200GeV

STAR Preliminary4.0

4.0 1

P

pbLdt

STAR Projections for 2006

2006) (run 5.0

10 1

P

pbLdt


July 6th

Run 5 ALL(): First constraints for ∆G(x)

Comparison with ∆G from QCD analysis ofDIS data: M. Glück, E. Reya, M. Stratmann, and W. Vogelsang, Phys. Rev. D 53 (1996) 4775.

¨

standard ∆G from DIS

∆G =0

max

∆G from

DIS

min ∆G possibleExcludes large gluon spincontributions!

Needs to be quantified with NLO pQCD analysis!

2005) (run 45.0

7.2 1

P

pbLdt

40% scale error (missing abso-lute polarization measurement).


July 6th

NLO QCD Analysis of DIS A1 + ALL(π0)

M. Hirai, S. Kumano, N. Saito, hep-ph/0603212(Asymmetry Analysis Collaboration)

DIS A1 + ALL(π0)

ACC03

x

0.14 0.21 1.27 0.5 AAC03

10.0 0.25 1.08 0.47 A DIS

0.070.27 0.320.31 )(A DIS

)(

1

01

LLA

dxxG


July 6th

Final results on ∆G will come from combined NLO analysis of all channels at RHIC and in DIS

RHIC measurements will span broad range in x with good precision. multiple channels with independent theo. and exp. uncertainties.

Uncertainty through extrapolation to small x

s=200 GeV incl. 0 prod’n s=500 GeV incl. jet prod’n

∆G Measurements by 2012 see Spin report to DOE http://spin.riken.bnl.gov/rsc/

Transverse Spin AN for inclusive hadrons (BRAHMS, PHENIX, STAR)


July 6th

QCD Cross Sections for Transverse Spin

QCD: Asymmetries for transverse spin are small at high energies (Kane, Pumplin, Repko, PRL 41, 1689–1692 (1978) )

4q 10,20,3m example, N

qN AGeVsMeV

s

mA

QCD Test !


July 6th

QCD Cross Sections for Transverse Spin

QCD: Asymmetries for transverse spin are small at high energies (Kane, Pumplin, Repko, PRL 41, 1689–1692 (1978) )

Xpp π+

π-

π0

LR

N

LR

PA

1 :Observable

GeV 20s

Suggestions: Sivers-, Collins-, Qui-Sterman, Koike mechanisms !?

Experiment (E704, Fermi National Laboratory):

Can QCD be re-conciled withlarge transverse asymmetries?


July 6th

AN Results from PHENIX and STAR

PHENIX AN(π0) and AN(π0) at |η|<0.35

Phys.Rev.Lett.95:202001,2005

STAR AN(π0) at 3.4<η<4.0Phys.Rev.Lett.92:171801,2004and (hep-ex/0502040)

• Sizable asymmetries for xF > 0.4• Back angle data consistent with AN ~ 0


July 6th

K+

K-

BRAHMS ANPions

Kaons

Protons p

p

DIS 2006, prel. stat. errors only First AN for kaons and protons AN(K

-) and AN(p) don’t agree with naive expectation from valence quark fragmentation


July 6th

AN: Maximum Asymmetries Possible

(II) Transversity quark-distributions and Collins fragmentation

Correlation between proton- und quark-spin and spin dependent fragmentation

),()( 221

kzHxq

(I) Sivers quark and gluon distributions Correlation between proton-spin and transverse quark momentum

),( 21 kxf qT

M. Anselmino, M. Boglione, U. D’Alesio, E. Leader, S. Melis and F. Murgia hep-ph/0601205

quar

k-Si

vers

gluon-Sivers

Transversity x Collins

RHIC 2006: precision measurements of AN with ~ 20 x ∫Ldt and 2-3 x Pbeam

on tape:

QCD analysis to separate effects !?


July 6th

Measurement of Transversity- and Sivers-Distributions in Polarized p-p Collisions at

RHIC

AN excellent!

AN(jet/hadron-correlations) good (Sivers signature!)

AT (Collins FF) just enough

AT (Interference FF) just enough

AT (Drell Yan) no

ATT( Drell Yan) no

RHIC Luminosity?

RHIC II Luminosities

requires Collins and Interference FFs e+e- at Belle


July 6th

Transversity : correlation between transverse proton spin and quark spin

Sivers : correlation between transverse proton spin and quark transverse momentum

Boer/Mulders: correlation between transverse quark spin and quark transverse momentum

RHIC II Luminosity UpgradeTransversity & Sivers & Boer-Mulders in Drell

Yan

)()( 21 xqxqATT

M

SkPkxfxqA PTq

TT

)ˆ(

),()( 2211

M

SkPkxh

M

SkPkxhN qqqq

)ˆ(),(

)ˆ(),()( 2

212

11


July 6th

Sivers-Asymmetries, AT in Drell Yan (J. Collins et al.)

STAR for 125pb-1

Dedicated DY Experiment1250 pb-1

o 10 o’clock 100% transverse polarization

o mini-quads

o acceptance: -3 < η < 3

AT

Q=4GeV Q=20GeVQ=4GeV Q=20GeVAT


July 6th

Transversity in Drell Yan with a Dedicated Drell Yan Experiment for

Transverse Spin

ATT for Drell Yan with dedicated DY detector

projections for 1250pb-1 of running,5-10% higher polarization, with RHIC II luminosities and large acceptance

Drell Yan1.25fb-1, large acceptance detector for Drell Yan

This measurement appears to bealso possible at 500 GeV


July 6th

Summary

RHIC and it’s experiments are the world’s first facility capable of colliding high energy polarized protons and heavy ions.

Collider and Experiments are complete and first highstatistics polarized proton runs took place in 2005and 2006.

Hadron Collisions at RHIC provide a powerful experimental tool to study the structure of thenucleon. We are at the beginning of a broad new program on spin dependent nucleon substructureand phenomena in nucleon structure at low x.


July 6th

NLO QCD Analysis vs High pT Hadron Production in DIS

DIS A1 + ALL(π0)

DIS A1

DIS A1 + ALL(π0) + neg ΔGinitial

High pT hadron production provides additionalconstraints to fit for 0.07 < x < 0.3, high pT dataconsistent with the three fit results for ΔG/G


July 6th

D. Boer and W. Vogelsang,Phys.Rev. D 69 (2004) 094025

Back-to-back di-Jets: Access to Gluon Sivers Function

Current measurements should be sensitive at the level of predictions

Measurements near mid-rapidity with STAR – search for spin-dependent deviation from back-to-back alignment

> 7 GeV trigger jet> 4 GeV away side jet

PHENIX: measurement of back-to-back di-hadrons.


July 6th

2P

)( 1xqi

)( 2xqi

11Px

22Pxij

1ps IFF

Jet

Jet

),(

)()()(

21

43213

2121

7

TT

H kzIFFdxdx

qqqqdxqxq

dzdkdxdx

Xppd

Proton Structure

Hard Scattering Process

InterferenceFragmentation

Jian Tang , Thesis MIT, June 1999

R. Jaffe, X.Jin, J. Tang Phys. Rev. D57 (1999)5920

X. Ji, Phys. Rev. D49 (1994)114J. Collins, S. Heppelmann, G. Ladinsky, Nucl.Phys. B420 (1994)565

e+e- spin dep. FF

extract

pQCD PDFs

NN

NN

PA

beam

1 :Experiment

Best Approach to Transversity at RHIC ?!


July 6th

200 GeV

500 GeV

qqqqqq

m

I

2,3/ˆˆ4ˆ

1cos83.0,0

102

,

GeV,

Transverse Single Spin Asymmetry (Tang, Thesis, MIT)

)(ˆsin)(ˆsin...ˆ)()(

...ˆ)(ˆ)()(

)cos()sin(sinsin4

61

112

002

21

21

1010

zqzqxGxG

zqxGxq

NN

NN

PA

qqgg

qgqgI

beam

Maximum Asymmetry

][GeVp jetT

Func. ionFragmentat Pol. :

DFs quarkity Transvers:

Shifts Phase Pion Two: sin

Pair Yield Pion

I

)(ˆ

)(

:

zq

xq

N


July 6th

Example:

MeV MeV

GeV

GeV

950800

4

4

22

21

, 21

m

pp

E

TT

32 1pb

Rates for Asymmetries in Interference Fragmentation in PHENIX for 32 pb-1

pair vsAsymmetry on iesUncertaint Tp

1%

2%

IFF from BelleAT from STAR+PHENIX


July 6th

Collins (and Interference) Fragmentation Function Measurement in e+e- at Belle

1hP

2hP

)(cosq 2

111

11212

21

21 zHzHyBddzdzd

Xhheedσ

T

2-hadron inclusive transverse momentum dependent cross section:

e+e- CMS frame:

e-

e+

R. Seidl, spin: Th 17:30


July 6th

Collins Asymmetries for π+π- Pairs

• Experimental method to remove acceptance effects and asymmetries from QCD radiative processes.

• First direct measurement of the Collins function.

• First QCD analysis (Anselmino et al.) for Hermes and Belle data show good agreement between Belle FF and Hermes

• See this weeks PRL for details..z1

z2


July 6th

LO-QCD Analysis of HERMES and Belle Results (Efremov, Goeke, Schweitzer, hep-ph/0603054)

BELLE PRELIMINARY HERMES PRELIMINARY

Combined fit to Hermes asymmetries (Transversity x Collins-

FF) and Belle asymmetries (Collins-FF2) Excellent agreement!

hadron physics at rhic

Documents

au gluon densities cgcprl

properties rhic

polarized pp collisions

rhic measure

heavy ioncollisions

quark matter andsurvey

quark gluon plasma

global nlo pqcd analysis