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 STAR STAR pp2pp pp2pp M. Grosse Perdekamp UIUC and RBRC Observables in Antiproton-Proton Interactions and their Relevance to QCD
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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
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
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