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RHIC Spin Physics. M. Grosse Perdekamp University of Illinois and RBRC. STAR. Physics goals Experimental tools Polarized proton-proton collisions at high energies Results and outlook Gluon Spin Transverse spin physics W-physics and upgrades. - PowerPoint PPT Presentation
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RHIC Spin Physics M. Grosse Perdekamp University of Illinois and RBRC
International Workshop on Deep Inelastic Scattering, April 20-24, 2006 ,Tsukuba, Japan
o Physics goals
o Experimental tools
Polarized proton-proton collisions at high energies
o Results and outlook
Gluon Spin Transverse spin physics W-physics and upgrades
STARSTAR
RHIC Spin Overview 2 April 20th
RHIC five complementary experiments
RHIC: ion-ion and polarized p-p Collider
pp2pppp2pp
RHIC Spin Overview 3 April 20th
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)
C. Cagliardilow-x: Sat.11.10
very active field: eg. 74 PRL letters in the first 5 years
RHIC Spin Overview 4 April 20th
available channels
jets, hadrons, photons, photon-jet, heavy flavor
Single spin lepton asym-metries in W-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
RHIC Spin Overview 5 April 20th
Access to Parton Distributions at RHIC
)(),(),(),( xGxqxGxqdp
d
T
Measure: (spin dependent) cross sections
QCD analysis: (spin dependent) distribution functions
RHIC Spin Overview 6 April 20th
Example:G(x) from a global NLO pQCD analysis with projected future direct photon data from
PHENIX
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
RHIC Spin Overview 7 April 20th
Inclusive Hadron Cross Sections vs NLO QCD
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
RHIC Spin Overview 8 April 20th
Theory calculation show good agreement with the experimentalcross section.
Direct Photons and Inclusive Jets vs NLO pQCD
M.Miller, hadronic final states: Sat.14.20
Inclusive Jet Cross sectionDirect Photon Cross section
STAR Preliminary
PHENIX Preliminary
Good agreement between NLO pQCD calculations and experiment at RHIC ! Use NLO pQCD analysis to extract (spin dependent) quark and gluon distributions from RHIC data!
M. Stratmann, spin: Fr 16:30
Theory perspective:
RHIC Spin Overview April 20th
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
Last Week at RHIC
peak average design
L 2.5 1.2 6.0
P 67% 61% 70%
Luminosity in 1031cm-2s-1
A. Bravar, spin: Fr 16:10
Generous support fromRIKEN, Japan and DOE
RHIC Spin Overview 10
April 20th
Polarized p-p at RHIC: Detector Instrumentation
(I) Upgrades to adapt “heavy ion detectors” for high rate p-p environment (eg. PHENIX trigger, STAR EMC, STAR tracking at high momentum)
(II)Local polarimeters to verify polarization direction at the interaction point (important for longitudinal spin!)
(III)Relative luminosity: arises in calculating asymmetries between yields from different bunch crossings, say i and j eg.
F. Simon, spin: Sa10:20
L
LR
jNR iN
jNR iN
PPA
ybLL ,
) crossing( )crossing(
) crossing( )crossing(1
RHIC Spin Overview 11
April 20th
100% transverse spin!Two spectrometer armswith good particle ID athigh momenta
BRAHMS: AN for charged π,K, p
RHIC Spin Overview 12
April 20th
PHENIX spin physics program: ∆G, ∆q/∆q, Sivers, δq
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.
RHIC Spin Overview 13
April 20th
STAR spin physics program: ∆G, ∆q/∆q, Sivers, δq
Large acceptance TPC and EMC -1<η<2
RHIC Spin Overview 14
April 20th
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)
RHIC Spin Overview 16
April 20th
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
J. Kiryluk, spin: Sa 9:00
STAR Preliminary
4.0
4.0 1
P
pbLdt
STAR Projections for 2006
2006) (run 5.0
10 1
P
pbLdt
RHIC Spin Overview 17
April 20th
Run 5 ALL(): First constraints for ∆G(x)
Comparision 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
Y. Fukao, spin: Sa 9:40
40% scale error (missing abso-lute polarization measurement).
M. Liu, spin: Sa 9:20
RHIC Spin Overview 18
April 20th
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
M. Hirai, spin: Sa 12:10
RHIC Spin Overview 19
April 20th
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
RHIC Spin Overview 20
April 20th
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)
C. Cagliardi, spin: Fr14:20
K. Tanida, spin: Fr14:40
J.H. Lee, spin: Fr15:00
RHIC Spin Overview 22
April 20th
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):
4q 10,20,3m example, N
qN AGeVsMeV
s
mA
QCD Test !
Can QCD be re-conciled withlarge transverse asymmetries?
RHIC Spin Overview 23
April 20th
STAR: AN for backward angles from 2003 data
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)
C. Cagliardi, spin: Fr14:20
K. Tanida, spin: Fr14:40
update!
• Sizable asymmetries for xF > 0.4• Back angle data consistent with AN ~ 0• Updated results in parallel session!
RHIC Spin Overview 24
April 20th
BRAHMS: AN for charged pions
xF x 100
pT vs XF
xF x 100
AN for pions:
NN = -0.08 +- 0.005 +- [0.02] = -0.08 +- 0.005 +- [0.02]
in 0.17 < xin 0.17 < xFF < 0.32 < 0.32
NN = +0.05 +- 0.005 +- [0.015]= +0.05 +- 0.005 +- [0.015]
o Expect new results from run 2005 for pions but also kaons and protons.
What can be learned by analyzing precision RHIC data on AN for different kinematics and different final state hadrons (Collins effect for kaons, protons)?
J.H. Lee, spin: Fr15:00
RHIC Spin Overview 25
April 20th
Large AN: mainly two mechanisms
(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
Transverstiy x Collins
RHIC Spin Overview 26
April 20th
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.
RHIC Spin Overview 27
April 20th
Measurement of Transverse Parton Distributions at RHIC
AN yes, very good
AN(back-to-back) good (Sivers signature!)
AT (Collins FF in jets) fair
AT (Interference FF) fair
ATT (Jets) systematics limited
AT (Drell Yan)
ATT( Drell Yan)
Direct photons (AN,AT(CFF, IFF))
RHIC by 2009 at 200 GeV
∫Ldt ~275pb-1 delivered
∫Ldt ~100pb-1 accepted(eg. PHENIX: vertex cut,trigger efficiencies, dutyfactor)
∫Ldt ~25 pb-1 transverse
RH
IC II
luminosity sufficient?
RHIC Spin Overview 28
April 20th
Collins 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
RHIC Spin Overview 29
April 20th
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!
Plans for the measurement of spin dependent quark and anti-quark in W-production at RHIC
RHIC Spin Overview 31
April 20th
Projected Sensitivities in PHENIX
Machine and detector requirements:Machine and detector requirements:
– ∫Ldt=800pb-1, P=0.7 at √s=500 GeV
– required upgrades:
high rate muon trigger (PHENIX)
high momentum tracking (STAR)
2009 to 2012 running at √s=500 GeVis projected to yield ∫Ldt ~950pb-1
RHIC Spin Overview 32
April 20th
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 a first highStatistics polarized took place in 2005. Run 2006consists of 16 weeks for proton-running.
Polarized Protons at RHIC provide a powerful experimental tool to study the structure of thenucleon. We are at the beginning of a broad new program on nucleon substructure.
RHIC Spin Overview 33
April 20th
Physics vs Luminosity and Polarization at RHIC
2005 2006 2007 2008 2009 …. 2012 (RHIC II)
10 pb-1 …………………………………… 275pb-1 …….. 950pb-1
√s= ……………………….. 200 GeV …………………......... 500 GeV|
P= 0.5 0.6 0.7 ……………………………………
Inclusive hadrons + Jets ~ 25% Transverse Physics Charm Physics direct photons bottom physics W-physics
ALL(hadrons, Jets) ALL(charm)
ALL(γ) AL(W)
L= 1x1031cm-2s-1 6x1031cm-2s-1 1.6x1032cm-2s-1
see Spin report to DOE http://spin.riken.bnl.gov/rsc/
@ 200GeV @ 500GeV
RHIC Spin Overview 34
April 20th
Carbon CNI Polarimeter in the AGS: Polarization during Acceleration
raw
asy
mm
etry
= A
N
PB
12+ 36- 36+G = 1.91 Ebeamintrinsic: G =
imperfection: G = n
each point = 50 MeV step
48-
red line: simulation of polarization losses assuming constant AN
RHIC Spin Overview 35
April 20th
Run 04+05: The Polarized Jet Target for RHIC
Polarized Hydrogen Gas Jet Target
thickness of > 1012 p/cm2
polarization > 92.4% (+/-2)%!
no depolarization from beam wake fields
Silicon recoil spectrometer to measure
• The left-right asymmetry AN in pp elastic
scattering in the CNI region to AN < 10-3
accuracy.
• Transfer this to the beam polarization
• Calibrate the p-Carbon polarimeters
• 2004 analysis Pb = 0.39+/-0.03
Courtesy Sandro Bravar, and Yousef Makdisi
RHIC Spin Overview 36
April 20th
Jet Profile and TOF vs Energy
Hor. pos. of Jet 10000 cts. = 2.5 mm
Num
ber
of e
last
ic p
p ev
ents
FWHM ~ 6 mmas designed
• recoil protons unambiguously identified !
CNI peak AN
1 < E REC < 2 MeV prompt eventsand beam-gas
sourcecalibration
recoil protons elastic pp ppscattering
background118 cts. subtracted
JET Profile: measured selecting ppelastic events
ToF vs EREC correlation
Tkin= ½ MR(dist/ToF)2
ToF < 8 ns
T Kin [MeV]
RHIC Spin Overview 37
April 20th
Bunch shuffle• Randomly
reassign helicity for each fill and recalculate asymmetry.
• Do 1000 times and look at distribution.
• Agree with expected distribution
• Bunch to bunch systematics smaller than current statistics.
5<pT<6 GeV/c 6<pT<7 GeV/c 7<pT<8 GeV/c 8<pT<9 GeV/c
1<pT<2 GeV/c 2<pT<3 GeV/c 3<pT<4 GeV/c 4<pT<5 GeV/c
RHIC Spin Overview 38
April 20th
Run5 0 Cross Section
• Consistent with previous PHENIX results from runs 3+4
• Extends previous results to pT of 20 GeV/c.
• Theory is consistent with data over nine orders of magnitude.
preliminary0 cross section vs perturbative QCD (W. Vogelsang)
Data – Theory)/Theory