recent results from high-energy longitudinal polarized proton-proton collisions at 200gev at rhic
DESCRIPTION
Recent results from high-energy longitudinal polarized proton-proton collisions at 200GeV at RHIC. Tai Sakuma MIT. The gluon contribution to the proton spin, G, is poorly constrained. -. . q. p. p. p. g. Polarized DIS found that quarks carry only a small fraction - PowerPoint PPT PresentationTRANSCRIPT
Recent results from high-energy Recent results from high-energy longitudinal polarized proton-proton longitudinal polarized proton-proton collisions at 200GeV at RHICcollisions at 200GeV at RHIC
Tai Sakuma Tai Sakuma
MITMIT
Polarized DIS found that quarks carry
only a small fractionof the proton spin
Polarized DIS found that quarks carry
only a small fractionof the proton spin
≈0.2
proton spinquarks gluons orbital motions
The gluon contribution to the proton spin, The gluon contribution to the proton spin, G, is G, is poorly constrained.poorly constrained.
G is only looselyconstrained from polarized DIS data.
G is only looselyconstrained from polarized DIS data.
--
pp
ppgg
pp
polarized pp
One of the goals of RHIC-Spin is One of the goals of RHIC-Spin is to determine to determine G with polarized pp collisions.G with polarized pp collisions.
ppgg
pp
polarized pp
In proton-proton collisions,gluons are in the initial states at lowest order.
In proton-proton collisions,gluons are in the initial states at lowest order.
In polarized pp collisions, AIn polarized pp collisions, ALLLL is the most important is the most important quantity to measure to determine quantity to measure to determine G. G.
- the double spin asymmetry in polarized pp collisions
PRL 97 (2006) 252001
ppgg
pp
polarized pp
As an example of ALL, this is one of the early results from STAR.
As an example of ALL, this is one of the early results from STAR.
- sensitive to G
AALLLL
PRL 97 (2006) 252001
As an example of ALL, this is one of the early results from STAR.
As an example of ALL, this is one of the early results from STAR.
The result is compared with theory predictions from GRSV working group.
The result is compared with theory predictions from GRSV working group.
AALL LL is sensitive to is sensitive to GG
AALL LL is sensitive to is sensitive to GG
GRSV polarized pdfPRD 63 (2001) 094005
• GRSV - std
• GRSV - max• GRSV - min• GRSV - zero
GRSV polarized pdfPRD 63 (2001) 094005
• GRSV - std
• GRSV - max• GRSV - min• GRSV - zero
PRL 97 (2006) 252001
The result is compared with theory predictions from GRSV working group.
The result is compared with theory predictions from GRSV working group.
GRSV xGRSV xG(x) G(x)
Best fit to pDISLarge uncertainty
Best fit to pDISLarge uncertainty
3 extreme scenarios3 extreme scenarios
AALLLL is predicted for various final states with is predicted for various final states with
different different G modelsG models
jetjet
GRSV xGRSV xG(x) G(x)
J/J/
jetjet
ALL is measured for various final states
• 2006 RHIC Run• 4.7 [pb-1]• Polarization ~60%• Jet Patch Trigger
Energy in a patch of calorimeter towers (x = 1 x 1) > 8.3 GeV
• Midpoint Cone Algorithm Cone Radius = 0.7 • PARTICLE jet pT
Corrected measured jet pT to true jet pT
with Pythia MC sample
• 2006 RHIC Run• 4.7 [pb-1]• Polarization ~60%• Jet Patch Trigger
Energy in a patch of calorimeter towers (x = 1 x 1) > 8.3 GeV
• Midpoint Cone Algorithm Cone Radius = 0.7 • PARTICLE jet pT
Corrected measured jet pT to true jet pT
with Pythia MC sample
STAR inclusive jet ASTAR inclusive jet ALLLL
ALL systematics (x 10-3)
Jet Reconstruction + Trigger Bias
[-2, +5] (pT dep)
Non-longitudinal Polarization
~0.03 (pT dep)
Relative Luminosity 0.94
Backgrounds 0.5 (1st bin), 0.1(else)
systematicssystematics
STAR inclusive jet ASTAR inclusive jet ALLLL
The results are compared with the GRSV ALL predictions.The results are compared with the GRSV ALL predictions.
STAR inclusive jet ASTAR inclusive jet ALLLL
To quantify the impact on GTo quantify the impact on G
The series of G spanning G-min
and G-max
The series of G spanning G-min
and G-max
STAR inclusive jet ASTAR inclusive jet ALLLL
To quantify the impact on GTo quantify the impact on G
The series of G spanning G-min
and G-max
The series of G spanning G-min
and G-max
ALL predictions based on the series of G
ALL predictions based on the series of G
STAR inclusive jet ASTAR inclusive jet ALLLL
Confidence Levels from the comparisonConfidence Levels from the comparison
ALL predictions based on the series of G
ALL predictions based on the series of G
Comparison of the results with the series of the ALL predictions
Comparison of the results with the series of the ALL predictions
For example, the C.L. for G = 0.3 is about 0.1%. This means that if G = 0.3 is true, the probability that we observe ALL that is in worse agreement than the ALL we actually observed is 0.1 percent.
For example, the C.L. for G = 0.3 is about 0.1%. This means that if G = 0.3 is true, the probability that we observe ALL that is in worse agreement than the ALL we actually observed is 0.1 percent.
GRSV STD
allowed region
STAR inclusive jet ASTAR inclusive jet ALLLL
Confidence Levels from the comparisonConfidence Levels from the comparison
• The 2006 results excluded G < -0.7 and G > 0.2 with C.L. 90% within the GRSV framework.
• The results are consistent with pDIS data.
• The 2006 results excluded G < -0.7 and G > 0.2 with C.L. 90% within the GRSV framework.
• The results are consistent with pDIS data.
For example, the C.L. for G = 0.3 is about 0.1%. This means that if G = 0.3 is true, the probability that we observe ALL that is in worse agreement than the ALL we actually observed is 0.1 percent.
For example, the C.L. for G = 0.3 is about 0.1%. This means that if G = 0.3 is true, the probability that we observe ALL that is in worse agreement than the ALL we actually observed is 0.1 percent.
Impact on GImpact on GGRSV STD
allowed region
PHENIX Inclusive PHENIX Inclusive ππ00 A ALLLL
• • highly segmented EMCal
x = 0.01 x 0.01• Run 5
3.5 [pb-1]Polarization ~ 50%
• Run 67.5 [pb-1]Polarization ~ 60%Final scaling error will be
~10%• Soft physics contribution
~ 10% at 2 GeV• Corrected for the background ALL
• • highly segmented EMCal
x = 0.01 x 0.01• Run 5
3.5 [pb-1]Polarization ~ 50%
• Run 67.5 [pb-1]Polarization ~ 60%Final scaling error will be
~10%• Soft physics contribution
~ 10% at 2 GeV• Corrected for the background ALL
PHENIX Inclusive PHENIX Inclusive ππ00 A ALLLL
ALL predictions based on the series of G
ALL predictions based on the series of G
PHENIX Inclusive PHENIX Inclusive ππ00 A ALLLL
ALL predictions based on the series of G
ALL predictions based on the series of G
Comparison of the results with the series of the ALL predictions
Comparison of the results with the series of the ALL predictions
• Within the GRSV framework,
2min = 7/~7 NDF
2min + 3 -0.8 < G < 0.2
• Within the GRSV framework,
2min = 7/~7 NDF
2min + 3 -0.8 < G < 0.2
The constraints on The constraints on G G from the STAR and PHENIX resultsfrom the STAR and PHENIX results
inclusive jets
inclusive jets
inclusive 0inclusive 0
The analysis was done within the
GRSV framework
The analysis was done within the
GRSV framework
The combined results constrain G
The combined results constrain G
STAR and PHENIX results are consistent and complementarySTAR and PHENIX results are consistent and complementary
Beyond GRSV frameworkBeyond GRSV framework
The analysis was done within the
GRSV framework
The analysis was done within the
GRSV framework
Beyond GRSV frameworkBeyond GRSV framework
The analysis was done within the
GRSV framework
The analysis was done within the
GRSV framework
Beyond GRSV frameworkBeyond GRSV framework
The analysis was done within the
GRSV framework
The analysis was done within the
GRSV framework
The range of x probed is
0.02 < x < 0.3
The range of x probed is
0.02 < x < 0.3
Beyond GRSV frameworkBeyond GRSV framework
The analysis was done within the
GRSV framework
The analysis was done within the
GRSV framework
The range of x probed is
0.02 < x < 0.3
The range of x probed is
0.02 < x < 0.3
Gehrmann-Stirling Set C (GS-C) has
highly polarized gluon in low x and G = 1
Gehrmann-Stirling Set C (GS-C) has
highly polarized gluon in low x and G = 1
Beyond GRSV frameworkBeyond GRSV framework
The range of x probed is
0.02 < x < 0.3
The range of x probed is
0.02 < x < 0.3
Gehrmann-Stirling Set C (GS-C) has
highly polarized gluon in low x and G = 1
Gehrmann-Stirling Set C (GS-C) has
highly polarized gluon in low x and G = 1
ALL for GS-C is consistent with the
results from RHIC Spin
ALL for GS-C is consistent with the
results from RHIC Spin
Beyond GRSV frameworkBeyond GRSV framework
The range of x probed is
0.02 < x < 0.3
The range of x probed is
0.02 < x < 0.3
Gehrmann-Stirling Set C (GS-C) has
highly polarized gluon in low x and G = 1
Gehrmann-Stirling Set C (GS-C) has
highly polarized gluon in low x and G = 1
G = 1 is ruled out within the GRSV framework but is still possible for much different
shape of xG(x)
G = 1 is ruled out within the GRSV framework but is still possible for much different
shape of xG(x)
The range of x probed is
0.02 < x < 0.3
The range of x probed is
0.02 < x < 0.3
The low-x region needs to be measured.
The low-x region needs to be measured.500
GeVForward, +jet
500 GeV
Forward, +jet
Forward Meson Spectrometer (FMS)
Forward Meson Spectrometer (FMS)
New global analysis is starting at BNL.
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pp
ppgg
pp
pDIS datapDIS data
G(x) modelsG(x) models ALL predictionsALL predictions
ALL measurementsALL measurements
constrains on Gconstrains on G
New global analysis at BNLNew global analysis at BNL
1. include both pDIS and RHIC Spin data for global fits of the polarized pdf.
2. started at BNL in the Fall 2007.
3. collaborative effort oftheorists from GRSV, DNSandexperimentalists fromSTAR and PHENIX.
1. include both pDIS and RHIC Spin data for global fits of the polarized pdf.
2. started at BNL in the Fall 2007.
3. collaborative effort oftheorists from GRSV, DNSandexperimentalists fromSTAR and PHENIX.
New global analysis is starting at BNL.
--
pp
ppgg
pp
pDIS datapDIS data
ALL measurementsALL measurements
Summary
• ALL for various final states in polarized pp collisions is measured at 200 GeV at RHIC.
• ALL from RHIC is constraining G to -0.8 < G < 0.2 with 90% C.L. within the GRSV framework and the probed x range of 0.02 < x < 0.3.
• Significant measured sensitivity is expected at RHIC with , +jet channels and 500 GeV run with access to lower x.
• A global analysis of the polarized parton distributions with pDIS and RHIC data is starting at BNL.