hall c spin results and perspective · jefferson lab, univ. of virginia, virginia p. i. & s.u.,...

Hall C Spin Results and PerspectiveK. Slifer

University of Virginia

TopicsResonant Spin Structure

SANE

Semi-SANE

K. Slifer UGM05 – p.1/32

Resonant Spin Structure (RSS)of the Proton and Deuteron

Oscar A. Rondon Mark K. Jones(UVA) (JLab)

Analysis

Paul McKee, Karl Slifer, Shige TajimaFrank Wesselmann, Junho Yun, Hongguo Zhu

(Eric Christy, Peter Bosted)

E01-006 CollaborationUniv. Basel, Florida International Univ., Hampton Univ., Univ. of Massachusetts, Univ. of Maryland,

Mississippi State Univ.,North Carolina A&T Univ., Univ. of N. C. at Wilmington,Norfolk State Univ.,Old Dominion Univ.,S.U. at New Orleans, Univ. of Tel-Aviv,Jefferson Lab, Univ. of Virginia, Virginia P. I. & S.U., Yerevan Physics Institute


Goals

Measure proton and deuteron A1(W, Q2) and A2(W, Q2)

in the resonance region at moderate Q2.

Extract g1 and g2 structure functions and study:W–dependenceOnset of polarized local dualitytwist-3 effects in d2 matrix element


Experimental set-up in Hall C

W (GeV)

Q2 (

GeV

2 )

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2

P0 = 4.7, 4.1 GeV/c

Q2 ≈ 1.3 GeV2

W : 0.8 − 2.0 GeV

Pb = 65.6 ± 2.6 for B‖

Pb = 70.9 ± 1.7 for B⊥

I ≈ 100nABeam charge asym. < 0.1%


Polarized Target

Target Ladder2 NH3 cups2 ND3 cups

1 Carbon (7mm)

Target Field5 TeslaPara & perpendicular fields.

Polarization can be flipped by

180. Ran ± for equal times.

Target PolarizationNH3 : Pt ≈ 0.68 ± 0.017

ND3 : Pt ≈ 0.18 ± 0.007


Packing fractions

Packing fraction is ratio of NH3

NH3

Helium

1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=52.4%

1.2 1.4 1.6 1.8 2W (GeV)

45

50

55

60

65

Pac

king

fra

ctio

n (%

) Top , parallel field

NH3

Packing Fractions

NH3 ND3

B‖ B⊥ B‖ B⊥

Top 52.4% 58.9 55.2 –

Bottom 53.2 60.7 56.0 62.1


Packing fractions

Packing fraction is ratio of NH3 to (NH3 + He).

NH3

Helium

1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=52.4%

1.2 1.4 1.6 1.8 2W (GeV)

45

50

55

60

65

Pac

king

fra

ctio

n (%


NH3

Packing Fractions

NH3 ND3

B‖ B⊥ B‖ B⊥

Top 52.4% 58.9 55.2 –

Bottom 53.2 60.7 56.0 62.1


Packing fractions


1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

data

1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=52.4%

1.2 1.4 1.6 1.8 2W (GeV)

45

50

55

60

65

Pac

king

fra

ctio

n (%


NH3

Packing Fractions

NH3 ND3

B‖ B⊥ B‖ B⊥

Top 52.4% 58.9 55.2 –

Bottom 53.2 60.7 56.0 62.1


Packing fractions


1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=50%

1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=52.4%

1.2 1.4 1.6 1.8 2W (GeV)

45

50

55

60

65

Pac

king

fra

ctio

n (%


NH3

Packing Fractions

NH3 ND3

B‖ B⊥ B‖ B⊥

Top 52.4% 58.9 55.2 –

Bottom 53.2 60.7 56.0 62.1


Packing fractions


1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=60%

1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=52.4%

1.2 1.4 1.6 1.8 2W (GeV)

45

50

55

60

65

Pac

king

fra

ctio

n (%


NH3

Packing Fractions

NH3 ND3

B‖ B⊥ B‖ B⊥

Top 52.4% 58.9 55.2 –

Bottom 53.2 60.7 56.0 62.1


Packing fractions


1.4 1.6 1.8 2W (MeV)

5

10

15

20

Rat

e

PF=52.4%

1.2 1.4 1.6 1.8 2W (GeV)

45

50

55

60

65

Pac

king

fra

ctio

n (%


NH3

Packing Fractions

NH3 ND3

B‖ B⊥ B‖ B⊥

Top 52.4% 58.9 55.2 –

Bottom 53.2 60.7 56.0 62.1


Dilution factors

f =NPolNTot

1.2 1.4 1.6 1.8 2W (MeV)

0

5

10

15

20

Rat

e

Helium

Helium + Nitrogen

All

NH3

Hall C fit for F2 and R.(M. E. Christy)

QFS for A > 2

1200 1400 1600 1800 2000W (GeV)

0

0.1

0.2

Dilu

tion

fac

tor

Parallel field, Bottom cupParallel field, Top cupPerpendicular field, Bottom cupPerpendicular field, Top cup


Comparisons to carbon data

Carbon data used to fit QFS model.

P0 = 4.7 GeV/c

00.5

11.5

22.5

33.5

44.5

5

Rat

e

Monte CarloData

1 1.1 1.2 1.3 1.4 1.5 1.6W (GeV)

0.8

0.9

1

1.1

1.2

Rat

io

Compare data to Monte Carlo

Ratio of data to Monte Carlo

P0 = 4.1 GeV/c

0

2

4

6

8

10

12

14

Rat

e

DataMonte Carlo

1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2W (GeV)

0.8

0.9

1

1.1

1.2

Rat

io

Compare data to Monte Carlo

Ratio of data to Monte Carlo


Extracting Asymmetry

Raw Asymmetries

Araw = N+−N−

N++N−

N+, N− : Helicity gated counts, normalized by the charge and deadtime

Physics Asymmetries

A‖,⊥ = 1Cfrc

1fPbPt

Araw + Arc

f : ratio of rates from polarized nucleons to all nucleons.

Pb, Pt : beam and target polarizations.

C : corrections for 15N asymmetry (not applied yet).

frc, Arc : radiative corrections

POLRAD (Akusevich et al.) modified to include our data as input.


Proton Elastic Asymmetry

Ael =K1 cos θ?+K2

GEGM

sin θ? cos φ?

G2E

/G2M

+τ/ε

θ?, φ? = polar and azimuthal anglesbetween ~q and target spin

K1, K2 = kinematic factors

Sensitivity ‖ ⊥∆Ael/Ael

∆GEGM

/GEGM

0.02 1

A‖ used to determine PbPt

A⊥ measure GE

GM

0.4 1 2 3 4 5

Q2 (GeV

2)

0.0

0.2

0.4

0.6

0.8

1.0

µGE/G

M

MIT-Bates (1998)Mainz (2001)SLAC (target pol)Global Fit for xn data (J. Arrington, PRC 69)JLab Rosenbluth (2004)JLab Recoil polarizationRSS


Inelastic Asymmetries

15N asymmetry correction (≈ 1.02) not applied yet.

Radiative corrections have been applied to proton data.

Work on radiative correction for deuteron in progress.

Expected systematic errors:NH3 : 6% (relative)ND3 : 8% (relative)

A‖ and A⊥ transformed to A1 and A2 using Hall C F2

and R fit (M. E. Christy)


Asymmetries

1000 1200 1400 1600 1800 2000W (MeV)

−0.3

−0.2

−0.1

0.0

0.1

0.2

0.3

ProtonRadiative Corrections Applied

ParaPerpPrelim

inary


Asymmetries

1000 1200 1400 1600 1800 2000W (MeV)

−0.3

−0.2

−0.1

0.0

0.1

0.2

0.3

DeuteronNo Radiative Corrections Applied

ParaPerpPrelim

inary


Asymmetries

1000 1200 1400 1600 1800 2000W (MeV)

−0.3

−0.2

−0.1

0.0

0.1

0.2

0.3

Proton and Deuteron

ParaPerpPrelim

inary


Proton A1

0 0.2 0.4 0.6 0.8 1XBj

−1

−0.5

0

0.5

1

1.5

2

A1

E143 E155

PQCDBroken SU(6)

SU(6) Symmetric


Proton A1

0 0.2 0.4 0.6 0.8 1XBj

−1

−0.5

0

0.5

1

1.5

2

A1

E143 E155 SLAC fit


Proton A1

0 0.2 0.4 0.6 0.8 1XBj

−1

−0.5

0

0.5

1

1.5

2

A1

E143 E155 SLAC fitRSS

Preliminary


Proton A1

0 0.2 0.4 0.6 0.8 1XBj

−1

−0.5

0

0.5

1

1.5

2

A1

SLAC fitMAIDRSS

∆

D13(1520)

S11(1535)

Preliminary


Proton A2

0 0.2 0.4 0.6 0.8 1XBj

−0.5

−0.3

−0.1

0.1

0.3

0.5

0.7

0.9

A2

E155


Proton A2

0 0.2 0.4 0.6 0.8 1XBj

−0.5

−0.3

−0.1

0.1

0.3

0.5

0.7

0.9

A2

E155RSS

Preliminary


Proton A2

0 0.2 0.4 0.6 0.8 1XBj

−0.5

−0.3

−0.1

0.1

0.3

0.5

0.7

0.9

A2

E155RSSMAIDSoffer Limit

Preliminary


Proton g1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Xbj

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

g1p

E155

All pdfs evolved to Q2 = 1.3

GRSV, AAC have target mass correction.


Proton g1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Xbj

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

g1p

E155E143




Proton g1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Xbj

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

g1p

E155E143EG1A




Proton g1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Xbj

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

g1p

E155E143EG1ARSS

Prelim

inary




Proton g1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Xbj

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

g1p

S11(1535)

F15(1680)

∆

MAID E155RSS

Prelim

inary




Proton g1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Xbj

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

g1p

S11(1535)

F15(1680)

∆

BSB pdfGRSV pdf AAC pdfRSS

Prelim

inary


GRSV, AAC have target mass correction. K. Slifer UGM05 – p.15/32

Proton g2

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Xbj

-0.2

-0.15

-0.1

-0.05

0

g2p

∆

S11(1535)

MAIDg2 (JLab Hall C data)g2 (E155)Prel

iminary

Not for q

uotation

F15(1680)


Higher twist in g2

x0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

g 2p

-0.30

-0.20

-0.10

0.00

0.10

Preliminary (not for quotation)RSS g2

p

g2pWW

g2 = gWW2 + g2

Twist-2 : gWW2 = −g1 +

∫ 1

xg1

y dy


Twist-3 matrix element d2

d2 = 3

∫ 1

0

x2(g2 − gWW2 )dx

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1X

-0.05

0

0.05

2 x2 (

g1 +

3/2

g2

)

RSS

Prelim

inary



d2 = 3

∫ 1

0

x2(g2 − gWW2 )dx

= 2

∫ 1

0

x2(g1 +3

2g2)dx

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1X

-0.05

0

0.05

2 x2 (

g1 +

3/2

g2

)

RSS

Prelim

inary



Integrated over0.29 < xbj < 0.84d2 = 0.0106 ± 0.0012

Lattice QCD at Q2 = 5

d2 = 0.0085 ± 0.0035QCDSF group , hep-lat/0011091

SLAC E155 at < Q2 >= 5

d2 = 0.0032 ± 0.0017

1 10

<Q2>

-0.01

-0.005

0

0.005

0.01

d2

RSS (0.29<x<0.84)QCDSFSLAC E155X

Prelim

inary


RSS Summary

Measured proton/deuteron A‖ and A⊥.

(Q2 ≈ 1.3 and 0.8 < W < 2.0)

Proton analysis complete. Extracted A1,A2,g1,g2 d2.

Compared to MAID model.

Compared to DIS data.

Made a qualitative comparison of g1 to PDFs.

Positive d2 measured with 10% error !

To Do:

Deuteron radiative corrections (in progress).

Quantitative duality analysis.

Structure function moments.


Spin Asymmetries on the Nucleon Experiment

E03-109

Basel, F.I.U. , Hampton, IHEP Protvino, Kent

State, Norfolk, N.C A&T, Rensselaer

Polytechnic, St. Norbert, Temple, TJNAF,

UVA, William & Mary, Yerevan

Spokesmen

Oscar A. Rondon (UVA)

Zein-Eddine Meziani (Temple)

Seonho Choi (Seoul)

0.3 0.4 0.5 0.6 0.7 0.8 0.9x

1

2

3

4

5

6

7

Q2

6.0 GeV4.8 GeV

Proton spin structure function g2(x, Q2) and spin Asymmetry A1(x, Q2)

2.5 < Q2 < 6.5 GeV2 and 0.3 < x < 0.8.

Study x and Q2 dependence, twist-3 effects, moments of g2 and g1, comparison with

Lattice QCD predictions, test polarized local duality for W > 1.4 GeV.


Experimental Setup


Big Electron Telescope Array (BETA)

3 subsystems

Lead glass calorimeter

Gas Cherenkov

Lucite hodoscope

Target field sweeps low E BG

Characteristics

∆Ω ≈ 194 msr

∆E ≈ 5%/√

E

∆θ ≈ 2

1000:1 pion rejection


Expected Results for proton g2 and A1


Expected Results x and Q2 dependence


Semi-Inclusive Spin Asymmetries on the Nucleon Experiment

Argonne, Duke, Florida International, Hampton, KentuckyMaryland, Massachusetts, Rensselaer Polytechnic, Norfolk, ODU

Regina, Rutgers, Temple, TJNAF, UVA, William & Mary, Yerevan Physics I.

P. Bosted D. Day X. Jiang M. Jones

(JLab) (UVA) (Rutgers) (JLab)

Proton and deuteron semi-inclusive longitudinal spin asymmetries

Polarized DIS reactions p(e, e′h) and d(e, e′h) for h = π±,K±

1.2 < Q2 <3.1 GeV2

0.12 < x < 0.43,

Spin flavor decomposition

emphasis on NLO spin flavor decomposition to extract ∆uv , ∆dv and ∆u − ∆d

based on measurement of combined asymmetry, Aπ+−π−

1N.

Examine deviation from factorization

by comparing combined asymmetry, Aπ++π−

1Nwith the inclusive asymmetry, A1N .


Experiment Set-up

Electrons detected in BETA at 30

Hadrons detected in HMS at 10.8 and pcent = 2.7 GeV/c


Summary of Hall C spin program

RSS : A‖ and A⊥ in inclusive electron scattering on protons and deuterons.

SF and Spin Asymmetries at Q2 = 1.3 GeV2 and 0.8 < W < 2.0

SANE: A‖ and A⊥ in inclusive electron scattering on proton with large acceptancedetector (BETA)

Extract g1 and g2 in range2.5 < Q2 < 6.5 and 0.3 < x < 0.8

Semi-SANE: SIDIS reactions p(e, e′h) and d(e, e′h) for h = π±,K±.

1.2 < Q2 <3.1 GeV2, 0.12 < x < 0.43, 0.5 < z < 0.7

Spin flavor decomposition

“Test” of validity of factorization by checking if Aπ++π−

1Nequals the inclusive

asymmetry, A1N .


Sources of Systematic Error

15NH315ND3

Nitrogen polarization <1% 1%Radiative corrections 2% 3%

Beam Polarization 1.5% 1.5%Target polarization 2.5% 4%

Dilution factor 3% 3%Pions, deadtime 1% 1%

Errors from R and F2 3% 3%Total error 5.5% 6.8%


Compare proton A‖ and A⊥ w/o RC

1000 1200 1400 1600 1800 2000W (MeV)

-0.1

0

0.1

0.2

0.3

A||

A|| RC

A⊥ RCA|| No RC

A⊥ No RC

Proton Asymmetries

Prelim

inary

A⊥

andNot fo

r quotatio

n


A1 =C

D(A‖ − dA⊥)

A2 =C

D(c′A‖ − d′A⊥)

Kinematic variablesC, c′, d, d′(E, E′, θ), D(E, E ′, θ, R)(R = σL/σT )

d′ ≈ 1, c′ ≈ d ≤ 1 ( at RSS kinematics)


g1, g2 can be extracted directly from A‖, A⊥ or A1, A2

g1 =F1

1 + γ2(A1 + γA2)

g2 =F1

1 + γ2(A2

γ− A1) ; γ2 =

Q2

ν2

Need F1 = F2(1 + γ2)/2x/(1 + R) in the resonance region.

Measurement of F2 and R in resonance region


hall c spin results and perspective · jefferson lab, univ. of virginia, virginia p. i. & s.u.,...

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