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
Hadron Physics at RHIC 3 July 6th
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
Hadron Physics at RHIC 4 July 6th
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
Hadron Physics at RHIC 5 July 6th
Heavy Ion Physics
A brief history of Heavy Ion Experiment Bevalac AGS GSI SPS RHIC LHC
Find quark matter andsurvey it’s properties
Hadron Physics at RHIC 6 July 6th
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 ?
Hadron Physics at RHIC 8 July 6th
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
Hadron Physics at RHIC 9 July 6th
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?
Hadron Physics at RHIC 12
July 6th
Access to Nucleon Structure at RHIC
)(),(),(),( xGxqxGxqdp
d
T
Measure: (spin dependent) cross sections
QCD analysis: (spin dependent) distribution functions
Hadron Physics at RHIC 13
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
Hadron Physics at RHIC 14
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
Hadron Physics at RHIC 15
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 ?
Hadron Physics at RHIC 16
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
Hadron Physics at RHIC 17
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
Hadron Physics at RHIC 18
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
Hadron Physics at RHIC 19
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
Hadron Physics at RHIC 20
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
Hadron Physics at RHIC 21
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
Hadron Physics at RHIC 22
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
Hadron Physics at RHIC 23
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!)
RHIC
Hadron Physics at RHIC 25
July 6th
RHIC: ion-ion and polarized p-p Collider
Hadron Physics at RHIC 26
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%
Hadron Physics at RHIC 28
July 6th
2006: Figure of Merit Goals and Actual
P2L: Transverse
P4L: Longitudinal
0.88 1.11
~7 times Run-5
goals
Hadron Physics at RHIC 29
July 6th
100% transverse spin!Two spectrometer armswith good particle ID athigh momenta
BRAHMS: AN for charged π,K, p, low x
Hadron Physics at RHIC 30
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.
Hadron Physics at RHIC 31
July 6th
STAR: ∆G, ∆q/∆q, Sivers, δq, low x
Large acceptance TPC and EMC -1<η<2
Hadron Physics at RHIC 32
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)
Hadron Physics at RHIC 34
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
Hadron Physics at RHIC 35
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).
Hadron Physics at RHIC 36
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
Hadron Physics at RHIC 37
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)
Hadron Physics at RHIC 39
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 !
Hadron Physics at RHIC 40
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?
Hadron Physics at RHIC 41
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
Hadron Physics at RHIC 42
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
Hadron Physics at RHIC 43
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 !?
Hadron Physics at RHIC 44
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
Hadron Physics at RHIC 45
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
Hadron Physics at RHIC 46
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
Hadron Physics at RHIC 47
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
Hadron Physics at RHIC 48
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.
Hadron Physics at RHIC 49
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
Hadron Physics at RHIC 50
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.
Hadron Physics at RHIC 51
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 ?!
Hadron Physics at RHIC 52
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
Hadron Physics at RHIC 53
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
Hadron Physics at RHIC 54
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
Hadron Physics at RHIC 55
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
Hadron Physics at RHIC 56
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!