future perspectives of the high- energy polarized …...future perspectives of the high-energy...

Bernd Surrow

AGS-RHIC Users Meeting, QCD SymposiumUpton, NY, May 28, 2008 Bernd Surrow

1

Future perspectives of the high-energy polarized proton-proton

program at RHIC

Bernd SurrowAGS-RHIC Users Meeting, QCD SymposiumUpton, NY, May 28, 2008

Outline

Summary and Outlook

Theoretical foundation

2

!p !p

Highlights of recent results and achievements

Future polarized p-p physics program

Gluon polarizationQuark / Anti-Quark PolarizationTransverse spin dynamics

Future polarized p-p collider performance


Theoretical foundation 3

Exploring the proton spin structure and dynamics

CP Violation

?

Non-linearity,

Confinement,

AdS/QCD

QCD

Background

EIC

QCD Theory

Hadron Structure

(JLAB 12 GeV, RHIC-Spin)

Relativistic

Heavy Ion Physics

(RHIC, LHC & FAIR)

Technology FrontierExamples: beam cooling,

energy recovery linac,

polarized electron source,

superconducting RF

cavities

High Energy

Physics(LHC, LHeC,

Cosmic Rays)

Condensed

Matter Physics Bose-Einstein Condensate

Spin Glasses

Graphene

Lattice QCD New Generation

of Instrumentation

Physics of Strong

Color Fields

ab initio

QCD Calculations

& Computational

Development

Understanding

of Initial Conditions,

Saturation, Energy Loss

Valence ↔ Sea

GPDs

Saturation ModelsColor Glass Condensate

Fundamental

Symmetries

QCD

Structure and dynamics of proton (mass) (→ visible universe) originates from QCD-interactions!

What about spin as another fundamental quantum number?

Synergy of experimental progress and theory (Lattice QCD / Phenomenology incl.

phenomenological fits / Modeling) critical!



General

4

Mom

entu

m

cont

ribu

tion

Spin contribution

f(x) =

f+(x) + f!(x)

+

!f(x) =

f+(x)! f!(x)

!

p

p

pTx1

x2

d!pp ! f1 " f2 " !h "Dhf Factorization

e!

X

e

p

xQ2

W 2 ! Q2/x

d!ep ! F2 =!

q

xe2qfq(x)

Universality


Theoretical foundation5

Precision measurements (e.g. F2) ⇒ Precision on quark/gluon structure

0

0.2

0.4

0.6

0.8

1

-410 -310 -210 -110 10

0.2

0.4

0.6

0.8

1

HERA I PDF fit (prel.)

CTEQ6.1M

HERA I PDF fit (prel.)

CTEQ6.1M

x

xf 2 = 10 GeV2Q

vxu

vxd

0.05)×xS (

0.05)×xg (

vxu

vxd

0.05)×xS (

0.05)×xg (

0

0.2

0.4

0.6

0.8

1

HER

A S

truct

ure

Func

tions

Wor

king

Gro

upA

pril

2008

H1 and ZEUS Combined PDF Fit

Evolution

H1 and ZEUS Combined PDF Fit

HER

A S

truct

ure

Func

tions

Wor

king

Gro

upA

pril

2008

x = 0.000032, i=22x = 0.00005, i=21

x = 0.00008, i=20x = 0.00013, i=19

x = 0.00020, i=18x = 0.00032, i=17

x = 0.0005, i=16x = 0.0008, i=15

x = 0.0013, i=14x = 0.0020, i=13

x = 0.0032, i=12x = 0.005, i=11

x = 0.008, i=10x = 0.013, i=9

x = 0.02, i=8

x = 0.032, i=7x = 0.05, i=6

x = 0.08, i=5x = 0.13, i=4

x = 0.18, i=3

x = 0.25, i=2

x = 0.40, i=1

x = 0.65, i=0

Q2/ GeV2

!r(x

,Q2 ) x

2i

HERA I e+p (prel.)Fixed TargetHERA I PDF (prel.)

10-3

10-2

10-1

1

10

10 2

10 3

10 4

10 5

10 6

10 7

1 10 10 2 10 3 10 4 10 5

Strong violation of scaling at low x and high Q2

In contrast to:

Low Q2 high x!

xg !!

dF2

d lnQ2

"

e (kµ)

e (k /)

γ* (qµ)

P (p µ)X (pµ /)

D. de Florian et al., Phys. Rev. D71, 094018 (2005).

8

parabola and the 1! uncertainty in any observable would correspond to !"2 = 1. In order to account for unexpectedsources of uncertainty, in modern unpolarized global analysis it is customary to consider instead of !"2 = 1 betweena 2% and a 5% variation in "2 as conservative estimates of the range of uncertainty.

As expected in the ideal framework, the dependence of "2 on the first moments of u and d resemble a parabola(Figures 3a and 3b). The KKP curves are shifted upward almost six units relative to those from KRE, due to thedi"erence in "2 of their respective best fits. Although this means that the overall goodness of KKP fit is poorer thanKRE, #d and #u seem to be more tightly constrained. The estimates for #d computed with the respective best fitsare close and within the !"2 = 1 range, suggesting something close to the ideal situation. However for #u, they onlyoverlap allowing a variation in !"2 of the order of a 2%. This is a very good example of how the !"2 = 1 does notseem to apply due to an unaccounted source of uncertainty: the di"erences between the available sets of fragmentationfunctions.

-0.2

0

0.2

0.4

-0.2

0

0.2

0.4

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

10-2

10-2

x(!u+!u–)

x(!d+!d–)

x!uv

x!dv

x!g–

x!u–

xBj

x!d–

xBj

x!s–

xBj

KRE (NLO)

KKP (NLO)unpolarizedKRE "

2KRE "

min+1

KRE "2

KRE "min

+2%

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

10-2

FIG. 4: Parton densities at Q2 = 10 GeV2, and the uncertainty bands corresponding to !!2 = 1 and !!2 = 2%

An interesting thing to notice is that almost all the variation in "2 comes from the comparison to pSIDIS data.The partial "2 value computed only with inclusive data, "2

pDIS , is almost flat reflecting the fact the pDIS data are

not sensitive to u and d distributions. In Figure 3, we plot "2pDIS with an o"set of 206 units as a dashed-dotted line.

The situation however changes dramatically when considering #s or #g as shown in Figures 3c and 3f, respectively.In the case of the variation with respect to #s, the profile of "2 is not at all quadratic, and the distribution is muchmore tightly constrained (notice that the scale used for #s is almost four times smaller than the one used for lightsea quarks moments). The "2

pDIS corresponding to inclusive data is more or less indi"erent within an interval aroundthe best fit value and increases rapidly on the boundaries. This steep increase is related to a positivity constraints on!s and !g. pSIDIS data have a similar e"ect but also helps to define a minimum within the interval. The preferredvalues for #s obtained from both NLO fits are very close, and in the case of KRE fits, it is also very close to thoseobtained for #u and #d suggesting SU(3) symmetry.

-0.04

-0.02

0

0.02

0.04

-0.04

-0.02

0

0.02

0.04

-0.04

-0.02

0

0.02

0.04

10 -2 10 -1

DSSVDNS KREDNS KKP

DSSV !"2=1DSSV !"2=2%

x!u–

x!d–

x!s–

x

GRSV maxgGRSV ming

x!g

x

-0.2

-0.1

0

0.1

0.2

0.3

10 -2 10 -1 1

D. de Florian et al., hep-ph/0804.0422

u/d sea-quarks

undetermined!


Theoretical foundation6

What do we know about the polarized quark and gluon distributions?

12

= !Sq" + !Sg" + !Lq" + !Lg"

!" = !u + !u + !d + !d + !s + !s

!G

Spin carried by quarks is very small (ΔΣ ∼ 0.4)!

!qi(Q2) =! 1

0!qi(x,Q2)dx !G(Q2) =

! 1

0!g(x,Q2)dx

12!"

Substantial

improvement

for 0.05<x<0.2

Large

uncertainties at

low x



Gluon polarization - Extraction

7

Extract Δg(x,Q2) through

Global Fit (Higher Order

QCD analysis)!

!G(Q2) =! 1

0!g(x,Q2)dx

ALL =d!!

d!

!f2!f1 aLL =!!h

!h

!!f1 "!f2 " !h · aLL "Dh

f

f1 " f2 " !h "Dhf

Input

long-range short-range long-range

!f1

!f2

!h

-1

-0.75

-0.5

-0.25

0

0.25

0.5

0.75

1

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1cosΘ*

a LL

gg ! gg

qg ! qg

qq ! qq qq ! qq

gg ! qq

xT = 2pT /!

s

Inclusive Jet production (200GeV: Solid line / 500GeV: Dashed line)

00.10.20.30.40.50.60.7

0 10 20 30 40 50 60 70 80 90 100pT

σij/σ

tot

-1<η<1 gg qg qq

00.10.20.30.40.50.60.7

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5XT

σij/σ

tot

-1<η<1 gg qg qq



Gluon polarization - Inclusive Measurements

8

part

onpa

rtic

lede

tect

or

Jet

π0π+

g

q

€

Δg

€

Δq



Gluon polarization - Correlation Measurements

Correlation measurements provide access to partonic

kinematics through Di-Jet/Hadron production and Photon-Jet

production

Di-Jet production / Photon-Jet production

Di-Jets: All three (LO) QCD-type processes contribute: gg, qg and

gg with relative contribution dependent on topological coverage

Photon-Jet: One dominant underlying (LO) process

Larger cross-section for di-jet production compared to photon

related measurements

Photon reconstruction more challenging than jet reconstruction

Full NLO framework exists ⇒ Input to Global analysis

9

M =!

x1x2s !3 + !4 = lnx1

x2

p

p

pTx1

x2

gg, qg, qq

Di-Jet production

p

p

pTx1

x2

qg

Photon-Jet production

RHICBOS W simulation at 500GeV CME

00.10.20.30.40.50.60.70.80.9

1

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W+ for CTEQ5M

Total cross-section: 14.41<ye<2

00.10.20.30.40.50.60.70.80.9

1

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W- for CTEQ5M

Total cross-section: 8.01<ye<2’

0123456789

10

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W+ for CTEQ5M

Total cross-section: 134.7No cuts

0123456789

10

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W- for CTEQ5M


AWL =

1P

N+(W )!N!(W )N+(W )!N!(W )

W! ! e! + !e

W+ ! e+ + !e

RHICBOS W simulation at 500GeV CME

0123456789

10

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W+ for CTEQ5M

Total cross-section: 101.0-1<ye<1

0123456789

10

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W- for CTEQ5M

Total cross-section: 20.5-1<ye<1’

0123456789

10

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W+ for CTEQ5M


0123456789

10

0 20 40pT (GeV)

d!/d

p T (pb

/GeV

)

W- for CTEQ5M




Quark / Anti-Quark Polarization - W production

10

!d + u!W+

!u + d!W+

!d + u!W!

!u + d!W!

!d + u!W+

!u + d!W+

W!

Key signature: High pT lepton (e-/e+ or

μ-/μ+) (Max. MW/2) - Selection of

W-/W+ : Charge sign discrimination of

high pT lepton

Required: Lepton/Hadron

discrimination

W+ pT > 20GeV/c

y lepton y lepton

W! pT > 20GeV/c

AL

AL



Quark / Anti-Quark Polarization - Sensitivity in W production

11

Large uncertainties for polarized anti-quarks reflected in leptonic asymmetries!

!u !u

!d

!d

x1 =MW!

seyW x2 =

MW!s

e!yW

Theoretical framework for leptonic

asymmetries exists (RHICBOS) ⇒ Basis for

input to global analysis!

Reconstruction of W-rapidity only possible

in approximative way in forward direction

Important contribution from forward and

mid-rapidity region

AW!

L = !!d(x1)u(x2)!!u(x1)d(x2)d(x1)u(x2) + u(x1)d(x2)



Transverse spin dynamics

12

Basic, naive QCD calculations (leading-twist,

zero quark masses) predict: AN=0 (AN ~ mq/

√s)

Qiu and Sterman (Initial-state twist-3)/

Koike (final-state twist-3)

Sivers: k⊥ in initial state (Correlation of

quark k⊥ and transverse proton spin):

⇒ Orbital momentum

Collins: k⊥ in final state (Correlation of

transverse quark spin and k⊥ of hadron):

⇒ Transversity

Study transverse spin effects:

AN =!! ! !"!! + !"

Single transverse-spin asymmetry



Cross Section Results

13

Good agreement between data and NLO

calculations for neutral pion production at

forward and central rapidity



Cross Section Results

14

Good

agreement

between data

and NLO

calculations for

jet production

and prompt

photon

production at

central rapidity

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

10 -4 10 -3 10 -2 10 -1 1x

x!g(

x,Q

2 )

GRSV-MAX !g = g

GRSV-STD !g = !gstd

GRSV-ZERO !g = 0

GRSV-MIN !g = -g

Q2 = 1 GeV2



Gluon polarization - Inclusive Measurements

15

!G(Q2) =! 1

0!g(x,Q2)dx

!g < !g < +gExamine wide range in Δg:

GRSV-STD: Higher order QCD analysis of polarized DIS experiments!

xparton ! 2pT /"

s

-0.02-0.01

00.010.020.030.040.050.06

2 4 6 8 10 12pT (GeV)

A LL

GRSV-MAX !g = gmax

GRSV-STD !g = gstd

-1<"<2 Inclusive #0 production

-0.02-0.01

00.010.020.030.040.050.06

2 4 6 8 10 12pT (GeV)

A LL

-1<"<1 - Inclusive #+ / #-

GRSV #+

GRSV #-

-0.02-0.01

00.010.020.030.040.050.06

5 10 15 20pT (GeV)

A LL

GRSV-ZERO !g = 0GRSV-MIN !g = -gmax

-1<"<2 Inclusive jet production

-0.02-0.01

00.010.020.030.040.050.06

5 10 15 20pT (GeV)

A LL

-1<"<2 Inclusive $ production

!G(Q2 = 1GeV 2) ! 1.8

!G(Q2 = 1GeV 2) ! 0.4



ALL Results - Inclusive Jet Production

16

-0.7 < η < 0.9

RUN 6 results: GRSV-MAX / GRSV-MIN ruled out - ALL result favor a gluon polarization in the measured x-region which falls in-between GRSV-STD and GRSV-ZERO

Consistent with RUN 5 result (Factor 3-4 improved statistical precision for pT>13GeV/c)

0.2

0.4

0.6

0.82/c2=100GeV2Q

-310 -210-110 1

0

X gluon

p =28 GeV/cT

p = 5.6 GeVT

/c

a)

1

!G

x10 5

0.25

0.5

0.75

1.0

0

frac

dN/d

(log

x)

-410

-310

-210

10

CL

/c ) 2 = 0.4 GeV2 G (Q! 20

-1 -0.5 0 0.5 1

-1

1

STARjet+X"pp

g=-g

!G

RSV

g=0

!G

RSV

GRS

V-st

d g=g

!G

RSV

b)

Pol. uncertainty

xparton ! 2pT /"

s



ALL Results - Neutral pion production

17

Consistent RUN 5/6 results

RUN 6 results: ALL result favor a

gluon polarization in the

measured x-region which falls in-

between GRSV-STD and GRSV-

ZERO



Global analysis incl. RHIC pp data

18

TABLE I: Data used in our analysis [2, 3], the individual!2 values, and the total !2 of the fit. We employ cuts ofQ, pT > 1GeV for the DIS, SIDIS, and RHIC high-pT data.

experiment data data points !2

type fitted

EMC, SMC DIS 34 25.7

COMPASS DIS 15 8.1

E142, E143, E154, E155 DIS 123 109.9

HERMES DIS 39 33.6

HALL-A DIS 3 0.2

CLAS DIS 20 8.5

SMC SIDIS, h± 48 50.7

HERMES SIDIS, h± 54 38.8

SIDIS, "± 36 43.4

SIDIS, K± 27 15.4

COMPASS SIDIS, h± 24 18.2

PHENIX (in part prel.) 200 GeV pp, "0 20 21.3

PHENIX (prel.) 62GeV pp, "0 5 3.1

STAR (in part prel.) 200 GeV pp, jet 19 15.7

TOTAL: 467 392.6

spond to the maximum variations for ALL computed withalternative fits consistent with an increase of !!2 = 1 or!!2/!2 = 2% in the total !2 of the fit.

Our newly obtained antiquark and gluon PDFs areshown in Fig. 2 and compared to previous analysis [4, 6].For brevety, the total !u+!u and !d+!d densities arenot shown as they are very close to all other fits [4–6].Here, the bands correspond to fits which maximize thevariations of the truncated first moments,

!f1,[xmin!xmax]j (Q2) !

! xmax

xmin

!fj(x, Q2)dx, (8)

at Q2 = 10 GeV2 and for [0.001 " 1]. As in Ref. [6]they can be taken as faithfull estimates of the typicaluncertainties for the antiquark densities. For the elusivepolarized gluon distribution, however, we perform a moredetailed estimate, now discriminating three regions in x:0.001-0.05, 0.05-0.2 (roughly corresponding to the rangeprobed by present RHIC data), and 0.2-1.0. Within eachregion, we scan again for alternative fits that maximizethe variations of the truncated moments !g1,[xmin!xmax],sharing evenly to !!2. In this way we can produce alarger variety of fits than for a single ([0.001"1]) moment,and, therefore, a more conservative estimate. Such a pro-cedure is not necessary for antiquarks whose x-shape isalready much better determined by DIS and SIDIS data.One can first of all see in Fig. 2 that !g(x, Q2) comes outrather small, even when compared to fits with a “moder-ate” gluon polarization [4, 6], with a possible node in thedistribution. This is driven by the RHIC data which puta strong constraint on the size of !g for 0.05 ! x ! 0.2

-0.02

-0.01

0

0.01

0.022 4 6 8

A!

ALL

0

pT [GeV]

PHENIX

PHENIX (prel.)

STAR

STAR (prel.)

DSSVDSSV "#

2=1

DSSV "#2/#

2=2%

Ajet

ALL

pT [GeV]

-0.05

0

0.05

10 20 30

FIG. 1: Comparison of RHIC data [3] and our fit. The shadedbands correspond to !!2 = 1 and !!2/!2 = 2% (see text).

-0.04

-0.02

0

0.02

0.04

-0.04

-0.02

0

0.02

0.04

-0.04

-0.02

0

0.02

0.04

10-2

10-1

DSSV

DNS

GRSV

DSSV "#2=1

DSSV "#2/#

2=2%

x"u–

x"d–

x"s–

x

Q2 = 10 GeV

2 GRSV max. "g

GRSV min. "g

x"g

x

-0.2

-0.1

0

0.1

0.2

0.3

10-2

10-1

FIG. 2: Our polarized sea and gluon densities compared toprevious fits [4, 6]. The shaded bands correspond to alterna-tive fits with !!2 = 1 and !!2/!2 = 2% (see text).

but cannot determine its sign as they mainly probe !gsquared. To explore this further, Fig. 3 shows the !2

profile and partial contributions !!2i of the individual

data sets for variations of the moment computed for thisx range. A nice degree of complementarity and consis-tency between is found. A small !g at x # 0.2 is alsoconsistent with data for ALL from lepton-nucleon scatter-ing [15], which still lack a proper NLO description. Thesmall x region remains still largely unconstrained.

We also find that the SIDIS data give rise to a ro-bust pattern for the sea polarizations, clearly deviating

395

400

405

410

-0.2 0 0.2

!2

"g1, [ 0.05-0.2 ]

all data setsx-range: 0.05-0.2

(a)

"!2"!i

"g1, [ 0.05-0.2 ]

PHENIXSTARSIDISDIS

(b) 0

5

10

15

-0.2 0 0.2

0.2

0.4

0.6

0.82/c2=100GeV2Q

-310 -210-110 1

0

X gluon

p =28 GeV/cT

p = 5.6 GeVT

/c

a)

1

!G

x10 5

0.25

0.5

0.75

1.0

0

frac

dN/d

(log

x)-410

-310

-210

10

CL

/c ) 2 = 0.4 GeV2 G (Q! 20

-1 -0.5 0 0.5 1

-1

1

STARjet+X"pp

g=-g

!G

RSV

g=0

!G

RSV

GRS

V-st

d g=g

!G

RSV

b)

Pol. uncertainty

hep-ph/0804.0422

Strong constraint on the size of Δg from RHIC

data for 0.05<x<0.2

Evidence for a small gluon polarization over a

limited region of momentum fraction

Important: Mapping x-dependence and extension

of x-coverage needed!

F x-0.6 -0.4 -0.2 0 0.2 0.4 0.6

NA

-0.4

-0.2

0

0.2

0.4 +!-!

BRAHMS Preliminary



AN results

19

Submitted to PRL, hep-ex/0801.2990

Precise measurement of AN as a function

of xF

AN calculations (Sivers / Twist-3) in

comparison to precise xF dependence of

measured AN ⇒ Constrain models!


Future polarized p-p collider performance

Polarized proton-proton operation at RHIC at 200 / 500 GeV

During last longest polarized proton-proton run (RUN 6):

Luminosity: ~1pb-1/day (~3pb-1/day design) delivered luminosity

Polarization: ~60% polarization (70% design)

20

500GeV development: Achieved 45%(*) beam polarization for single beam at 250GeV

Goal: At 70% beam

polarization

200GeV:

60⋅1030cm-2s-1

500GeV:

150⋅1030cm-2s-1

(*) Assumption: Analyzing power at 250GeV same as for 100GeV!



Gluon polarization - Projection Run 9

21

-0.2

-0.1

0

0.1

0.2

0.3

GRSVDNS

x!g w/Run 6

GRSV max. !gGRSV min. !g

x!g w/Run 9

x

DSSV

-0.2

-0.1

0

0.1

0.2

0.3

10 -1 1

395

400

405

410

-0.2 0 0.2

0

5

10

15

-0.2 0 0.2

395

400

405

410

-0.2 0 0.2

!2

"g1, [ 0.05-0.2 ]

all data sets

x-range: 0.05-0.2 "!2"!i

"g1, [ 0.05-0.2 ]

PHENIXSTARSIDISDIS

!2

"g1, [ 0.05-0.2 ]

RUN 9"!2"!i

"g1, [ 0.05-0.2 ]

0

5

10

15

-0.2 0 0.2

Substantial improvement on gluon polarization from inclusive measurements

Complementary information from STAR and PHENIX

RUN 6

x1 (2) =1!s

!pT3e

!3(!!3) + pT4e!4(!!4)

"

pT3 , !3

pT4 , !4



Gluon polarization - Correlation Measurements

22

η = 0

EastWest

η = -1η = 1

η = 2

Correlation measurements provide

access to partonic kinematics through

Di-Jet/Hadron production and Photon-

Jet production

2-2 processes:

cos !! = tanh!

"3 ! "42

"

M =!

x1x2s

!3 + !4 = lnx1

x2

p

p

x1

x2

gg, qg, qq

]2M [GeV/c20 30 40 50 60 70 80 90

10

210

310

410

DataPythia

)4! +

3!(2

1-0.2 0 0.2 0.4 0.6 0.8 1 1.2

210

310

410

*)|"|cos(0 0.1 0.2 0.3 0.4 0.5

10

210

310

410

/ ndf 2# 9.386 / 6Prob 0.153p0 0.0098± 0.9943

]2M [GeV/c20 30 40 50 60 70 80 900.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

/ ndf 2# 9.386 / 6Prob 0.153p0 0.0098± 0.9943

/ ndf 2# 9.386 / 6Prob 0.153p0 0.0098± 0.9943

/ ndf 2# 4.396 / 9Prob 0.8834p0 0.0101± 0.9983

)4! +

3!(2

1-0.2 0 0.2 0.4 0.6 0.8 1 1.20.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

/ ndf 2# 4.396 / 9Prob 0.8834p0 0.0101± 0.9983

/ ndf 2# 4.396 / 9Prob 0.8834p0 0.0101± 0.9983

/ ndf 2# 2.511 / 6Prob 0.8672p0 0.0101± 0.9995

*)|"|cos(0 0.1 0.2 0.3 0.4 0.50.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

/ ndf 2# 2.511 / 6Prob 0.8672p0 0.0101± 0.9995

/ ndf 2# 2.511 / 6Prob 0.8672p0 0.0101± 0.9995

cos !! = tanh!

"3 ! "42

"


Future polarized p-p physics program23

Data/MC comparison complete - Good agreement in Di-Jet variables

First cross-section and ALL measurement in progress

Correlation measurements: Di-Jet production - Data Understanding

M =!

x1x2s !3 + !4 = lnx1

x2

]2M [GeV/c20 30 40 50 60 70 80

LLA

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06STAR: east barrel - endcap

< 0.04! < 2.0, -1.0 <

3!1.0 <

MCGRSV stdGRSV m03GRSV zeroGS-C(pdf set NLO)

(P = 60%)-150 pb

NLOGRSV stdDSSV

]2M [GeV/c20 30 40 50 60 70 80

LLA

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06STAR: west barrel - endcap

+ X4 + jet3 jet" p + p = 200 GeVs

< 1.04! < 2.0, 0.0 <

3!1.0 <

]2M [GeV/c20 30 40 50 60 70 80

LLA

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06STAR: east barrel - east barrel and west barrel - west barrel

< 0.04! < 0.0, -1.0 <

3!-1.0 <

< 1.04! < 1.0, 0.0 <

3! 0.0 <

]2M [GeV/c20 30 40 50 60 70 80

LLA

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06STAR: east barrel - west barrel

< 0.04! < 1.0, -1.0 <

3!0.0 <

Scale uncertaintyGRSV stdDSSV

0.200.07

0.610.22

x1x2

0.330.04

0.870.12

x1x2

0.200.07

0.610.22

x1x2

0.120.12

0.370.37

x1x2



Gluon polarization - Di-Jets

24

Substantial improvement in

Run 9 from Di-Jet

production

Good agreement between

LO MC evaluation and full

NLO calculations

M =!

x1x2s !3 + !4 = lnx1

x2

]2M [GeV/c20 30 40 50 60 70 80 90 100 110

LLA

-0.005

0

0.005

0.01

0.015

0.02STAR: east barrel - endcap

< 0.04! < 2.0, -1.0 <

3!1.0 <

(P=70%)-1300pbNLO

GRSV stdDSSV

]2M [GeV/c20 30 40 50 60 70 80 90 100 110

LLA

-0.005

0

0.005

0.01

0.015

0.02STAR: west barrel - endcap

+ X4

+ jet3

jet" p + p

= 500 GeVs

< 1.04! < 2.0, 0.0 <

3!1.0 <

]2M [GeV/c20 30 40 50 60 70 80 90 100 110

LLA

-0.005

0

0.005

0.01

0.015

0.02STAR: east barrel - east barrel and west barrel - west barrel

< 0.04! < 0.0, -1.0 <

3!-1.0 <

< 1.04! < 1.0, 0.0 <

3! 0.0 <

]2M [GeV/c20 30 40 50 60 70 80 90 100 110

LLA

-0.005

0

0.005

0.01

0.015

0.02STAR: east barrel - west barrel

< 0.04! < 1.0, -1.0 <

3!0.0 <

Scale uncertaintyGRSV stdDSSV



Quark / Anti-Quark polarization program at PHENIX

Forward Muon Trigger layout

25

RPC1(a,b)RPC2 RPC2RPC3 RPC3

3 RPC planes for each muon chamber - Expected installation: Stations 2/3-North in 2009 - 2/3-South in 2010

FEE upgrade of muon tracking - Expected installation: North in Summer 2008 / South in Summery 2009



Quark / Anti-Quark polarization program at PHENIX

26

Main offline background: Low pT

hadrons decaying within muon tracker

volume mimicking a high pT track

Tight cuts reduce S/B ratio to 1/3

Hadron absorber after central

magnet yoke allows S/B ratio of 3/1



Quark / Anti-Quark polarization program at PHENIX (Forward rapidity)

27

Large asymmetries dominated by

quark polarization - Important

consistency check to existing DIS

data with 100pb-1 (Phase I)

Strong impact constraining unknown

antiquark polarization requires

luminosity sample at the level of

300pb-1 for 70% beam polarization

(Phase II)



Quark / Anti-Quark polarization program at STAR

28

Forward GEM Tracker: FGT

Charge sign identification for high momentum

electrons from W± decay (Energy determined

with EEMC)

Triple-GEM technology

FGT project:

ANL, IUCF, LBL, MIT, University of Kentucky,

Valparaiso University, Yale

Successful project review (Capital equipment

funding): January 2008

Expected installation: Summer 2010 FGTHFT




e/h separation: Full PYTHIA QCD background and W signal sample including detector effects

e/h separation based on global cuts (isolation/missing ET) and EEMC specific cuts as

With current algorithm: ET > 25GeV yields S/B > 1 (For ET < 25GeV S/B ~ 1/5) used for AL

uncertainty estimates



Conclusion:

Charge sign reconstruction impossiblebeyond η = ~1.3

TPC + FGT Tracking, pT = 30 GeV/c

6 triple-GEM disks, assumed spatial resolution 60μm in x and y (Fairly insensitive for60-100μm)

Charge sign reconstruction probability above 90% for 30 GeV pT over the full acceptance ofthe EEMC for the full vertex spread


Reach of EEMCAcceptance

Tue May 27 16:45:50 2008

, Pol=0.7, effi=70%, including QCD background, no vertex cut-1STAR projections for LT=300 pb

lepton ET (GeV)20 25 30 35 40 45 50

-0.6

-0.4

-0.2

0

0.2

0.4

GRSV-STDGRSV-VALDNS2005-MAXDNS2005-MINDSSV2008STAR projections

(W+) for positronL A Forward

lepton ET (GeV)20 25 30 35 40 45 50-0.4

-0.2

0

0.2

0.4

0.6

(W-) for electronL A Forward

lepton ET (GeV)20 25 30 35 40 45 50-0.6

-0.4

-0.2

0

0.2

0.4

(W+) for positronLBackward A

lepton ET (GeV)20 25 30 35 40 45 50-0.6

-0.4

-0.2

0

0.2

0.4

(W-) for electronLBackward A



Quark / Anti-Quark polarization program at STAR (Forward rapidity)

Large asymmetries dominated by

quark polarization - Important

consistency check to existing DIS

data with 100pb-1 (Phase I)

Strong impact constraining unknown

antiquark polarization requires

luminosity sample at the level of

300pb-1 for 70% beam polarization

(Phase II)Tue May 27 17:29:23 2008

, Pol=0.7, effi=70%, no QCD background, no vertex cut-1STAR projections for LT=300 pb

lepton ET (GeV)20 25 30 35 40 45 50

-0.6

-0.4

-0.2

0

0.2

0.4

GRSV-STDGRSV-VALDNS2005-MAXDNS2005-MINDSSV2008STAR projections

(W+) for positronL A Forward

lepton ET (GeV)20 25 30 35 40 45 50-0.4

-0.2

0

0.2

0.4

0.6

(W-) for electronL A Forward

lepton ET (GeV)20 25 30 35 40 45 50-0.6

-0.4

-0.2

0

0.2

0.4

(W+) for positronLBackward A

lepton ET (GeV)20 25 30 35 40 45 50-0.6

-0.4

-0.2

0

0.2

0.4

(W-) for electronLBackward A

Tue May 27 21:45:36 2008

, Pol=0.7, effi=70%, no QCD background, no vertex cut-1STAR projections for LT=300 pb

lepton ET (GeV) 20 25 30 35 40 45 50-0.8

-0.6

-0.4

-0.2

-0

0.2

| < 1!(W+) for positron |L A

lepton ET (GeV) 20 25 30 35 40 45 50

-0.2

0

0.2

0.4

0.6

0.8 GRSV-STDGRSV-VALDNS2005-MAXDNS2005-MINDSSV2008

-1STAR 300 pb

| < 1!(W-) for electron |L A



Quark / Anti-Quark polarization program at PHENIX / STAR (Mid-rapidity)

32

Preliminary projections at mid-rapidity (No QCD background effects included)

Important constraint on anti-u and in particular anti-d distribution functions at mid-

rapidity!




33

Conventional calculations predict the asymmetry to have the same sign in SDIS and γ+ jet whereas

calculations that account for repulsive interactions between like color charges predict opposite sign

Critical test on Sivers effect

Bacchetta et al., PRL 99, 212002




34

Important test at RHIC of fundamental QCD

prediction of non-universality of Sivers effect 0.1 0.2 0.3 x

Siv

ers A

mpl

itude

0

HERMES Sivers Results

Markus DiefenthalerDIS WorkshopMűnchen, April 2007

0


Summary and Outlook

Summary

Three key elements:

Gluon

polarization

Quark /

Anti-Quark Polarization

Transverse

spin dynamics

Critical:

35

Recorded Luminosity

Main physics Objective Remarks

~50pb-1 Gluon polarization using di-jets and precision inclusive measurements 200 GeV

~100pb-1W production (Important consistency

check to DIS results - Phase I)Gluon polarization (Di-Jets / Photon-Jets)

500 GeV

~300pb-1W production (Constrain antiquark

polarization - Phase II)Gluon polarization (Di-Jets / Photon-Jets)

500 GeV

~30pb-1 Transverse spin gamma-jet 200 GeV

~250pb-1 Transverse spin Drell-Yan (Long term) 200 GeV

Beam polarization: 70% / Narrow vertex region / Spin flipper for high precision asymmetry measurements

Critical: Sufficient running time!


Summary and Outlook36

E155

E143

SMC

HERMES

0.01

0.1

1

10

100 101 102 103 104

Q2(GeV2)

gp 1(x

,Q2)

+ C

(x)

x = 0.0007

x = 0.0025

x = 0.0063

x = 0.0141

x = 0.0245

x = 0.0346

x = 0.0490

x = 0.0775

x = 0.122

x = 0.173

x = 0.245

x = 0.346

x = 0.490

x = 0.735

EIC

Coverage

x

2.5 < Q2 < 7.5 GeV

2

1

0

10-3 10-2 10-1-1

e (kµ)

e (k /)

γ* (qµ)

P (p µ)X (pµ /)

Outlook

New insight into

spin structure

and dynamics of

the proton at a

future

Electron-Ion

Collider facility:

Precision inclusive measurements - Scaling

violation of g1p

⇒ Gluon polarization at low x

Semi-Inclusive measurements

⇒ Quark flavor studies at low x


Backup

AL sensitivity

37

!u

!d

!d

!u

future perspectives of the high- energy polarized …...future perspectives of the high-energy...

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