recent results from high-energy longitudinal polarized proton-proton collisions at 200gev at rhic

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.

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pp

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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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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.

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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.